Fundamentals of Industrial Hygine

FUNDAMENTALS OFINDUSTRIAL HYGIENEFifth Edition

3

I ndustrial hygiene is that science and art devoted to the antici-pation, recognition, evaluation, and control of those environ-

mental factors or stresses arising in or from the workplace thatmay cause sickness, impaired health and well-being, or significantdiscomfort among workers or among the citizens of the commu-nity. Industrial hygienists are occupational health professionalswho are concerned primarily with the control of environmentalstresses or occupational health hazards that arise as a result of orduring the course of work. The industrial hygienist recognizes thatenvironmental stresses may endanger life and health, acceleratethe aging process, or cause significant discomfort.

The industrial hygienist, although trained in engineering,physics, chemistry, environmental sciences, safety, or biology, hasacquired through postgraduate study or experience a knowledgeof the health effects of chemical, physical, biological, andergonomic agents. The industrial hygienist is involved in themonitoring and analysis required to detect the extent of exposure,and the engineering and other methods used for hazard control.

Evaluation of the magnitude of work-related environmentalhazards and stresses is done by the industrial hygienist, aided bytraining, experience, and quantitative measurement of thechemical, physical, ergonomic, or biological stresses. The indus-trial hygienist can thus give an expert opinion as to the degreeof risk the environmental stresses pose.

Industrial hygiene includes the development of correctivemeasures in order to control health hazards by either reducingor eliminating the exposure. These control procedures mayinclude the substitution of harmful or toxic materials with lessdangerous ones, changing of work processes to eliminate or min-imize work exposure, installation of exhaust ventilation systems,good housekeeping (including appropriate waste disposal meth-ods), and the provision of proper personal protective equipment.

An effective industrial hygiene program involves the antici-pation and recognition of health hazards arising from workoperations and processes, evaluation and measurement of the

Overview ofIndustrial Hygiene

by Barbara A. Plog, MPH, CIH, CSP

4 PROFESSIONAL ETHICSThe Occupational Health and Safety Team

6 FEDERAL REGULATIONS7 ENVIRONMENTAL FACTORS OR STRESSES

Chemical Hazards ➣ Physical Hazards ➣ Ergonomic Hazards➣ Biological Hazards

20 HARMFUL AGENTS–ROUTE OF ENTRYInhalation ➣ Absorption ➣ Ingestion

21 TYPES OF AIRBORNE CONTAMINANTSStates of Matter ➣ Respiratory Hazards

24 THRESHOLD LIMIT VALUESSkin Notation ➣ Mixtures ➣ Federal Occupational Safety andHealth Standards

26 EVALUATIONBasic Hazard-Recognition Procedures ➣ Information Required➣ Degree of Hazard ➣ Air Sampling

28 OCCUPATIONAL SKIN DISEASESTypes ➣ Causes ➣ Physical Examinations ➣ PreventiveMeasures

29 CONTROL METHODSEngineering Controls ➣ Ventilation ➣ Personal ProtectiveEquipment ➣ Administrative Controls

31 SOURCES OF HELP31 SUMMARY31 BIBLIOGRAPHY

C h a p t e r

1

magnitude of the hazard (based on past experience and study),and control of the hazard.

Occupational health hazards may mean conditions thatcause legally compensable illnesses, or may mean any conditionsin the workplace that impair the health of employees enough tomake them lose time from work or to cause significant discom-fort. Both are undesirable. Both are preventable. Their correc-tion is properly a responsibility of management.

PROFESSIONAL ETHICS In late 1994, the four major U.S. industrial hygiene organ-izations gave final endorsements to a revised Code of Ethicsfor the Practice of Industrial Hygiene. These organizationsare the American Conference of Governmental IndustrialHygienists (ACGIH), the American Academy of IndustrialHygiene (AAIH), the American Board of Industrial Hygiene(ABIH), and the American Industrial Hygiene Association(AIHA).

The new code defines practice standards (Canons of Eth-ical Conduct) and applications (interpretive guidelines). TheCanons of Ethical Conduct are as follows:

Industrial Hygienists shall practice their professionfollowing recognized scientific principles with the real-ization that the lives, health, and well-being of peoplemay depend upon their professional judgment and thatthey are obligated to protect the health and well-being ofpeople.

Industrial Hygienists shall counsel affected parties fac-tually regarding potential health risks and precautionsnecessary to avoid adverse health effects.

Industrial Hygienists shall keep confidential personaland business information obtained during the exercise ofindustrial hygiene activities, except when required by lawor overriding health and safety considerations.

Industrial Hygienists shall avoid circumstances wherea compromise of professional judgment or conflict ofinterest may arise.

Industrial Hygienists shall perform services only in theareas of their competence.

Industrial Hygienists shall act responsibly to upholdthe integrity of the profession.The interpretive guidelines to the Canons of Ethical Con-

duct are a series of statements that amplify the code (Figure1–1).

The Occupational Health and Safety Team The chief goal of an occupational health and safety programin a facility is to prevent occupational injury and illness byanticipating, recognizing, evaluating, and controlling occu-pational health and safety hazards. The medical, industrialhygiene, and safety programs may have distinct, additionalprogram goals but all programs interact and are often con-sidered different components of the overall health and safetyprogram. The occupational health and safety team consists,

then, of the industrial hygienist, the safety professional, theoccupational health nurse, the occupational medicine physi-cian, the employees, senior and line management, and oth-ers depending on the size and character of the particularfacility. All team members must act in concert to provideinformation and activities, supporting the other parts toachieve the overall goal of a healthy and safe work environ-ment. Therefore, the separate functions must be administra-tively linked in order to effect a successful and smoothly runprogram.

The first vital component to an effective health and safetyprogram is the commitment of senior management and linemanagement. Serious commitment is demonstrated whenmanagement is visibly involved in the program both bymanagement support and personal compliance with allhealth and safety practices. Equally critical is the assignmentof the authority, as well as the responsibility, to carry out thehealth and safety program. The health and safety functionmust be given the same level of importance and accounta-bility as the production function.

The function of the industrial hygienist has been definedabove. (Also see Chapter 23, The Industrial Hygienist.) Theindustrial hygiene program must be made up of several keycomponents: a written program/policy statement, hazardrecognition procedures, hazard evaluation and exposureassessment, hazard control, employee training, employeeinvolvement, program evaluation and audit, and record-keeping. (See Chapter 27, The Industrial Hygiene Program,for further discussion.)

The safety professional must draw upon specialized knowl-edge in the physical and social sciences. Knowledge of engi-neering, physics, chemistry, statistics, mathematics, andprinciples of measurement and analysis is integrated in theevaluation of safety performance. The safety professionalmust thoroughly understand the factors contributing toaccident occurrence and combine this with knowledge ofmotivation, behavior, and communication in order to devisemethods and procedures to control safety hazards. Becausethe practice of the safety professional and the industrialhygienist are so closely related, it is rare to find a safety pro-fessional who does not practice some traditional industrialhygiene and vice versa. At times, the safety and industrialhygiene responsibilities may be vested in the same individualor position. (See Chapter 24, The Safety Professional.)

The occupational health nurse (OHN) is the key to thedelivery of comprehensive health care services to workers.Occupational health nursing is focused on the promotion,protection, and restoration of workers’ health within thecontext of a safe and healthy work environment. The OHNprovides the critical link between the employee’s health sta-tus, the work process, and the determination of employeeability to do the job. Knowledge of health and safety regula-tions, workplace hazards, direct care skills, counseling,teaching, and program management are but a few of the keyknowledge areas for the OHN, with strong communication

PART I ➣ HISTORY AND DEVELOPMENT

4

CHAPTER 1 ➣ OVERVIEW OF INDUSTRIAL HYGIENE

5

Figure 1–1. The joint Code of Ethics for the Practice of Industrial Hygiene endorsed by the AIHA, the ABIH, the AAIH, and theACGIH. (From ACGIH Today! 3(1), January 1995.) These guidelines may be supplemented when necessary, as ethical issues andclaims arise.

skills of the utmost importance. OHNs deliver high-qualitycare at worksites and support the primary prevention dictumthat most workplace injuries and illnesses are preventable. Ifinjuries occur, OHNs use a case-management approach toreturn injured employees to appropriate work on a timelybasis. The OHN often functions in multiple roles withinone job position, including clinician, educator, manager,and consultant. (See Chapter 26, The Occupational HealthNurse.)

The occupational medicine physician has acquired, throughgraduate training or experience, extensive knowledge ofcause and effect relationships of chemical, physical, biologi-cal, and ergonomic hazards, the signs and symptoms ofchronic and acute exposures, and the treatment of adverseeffects. The primary goal of the occupational medicinephysician is to prevent occupational illness and, when illnessoccurs, to restore employee health within the context of ahealthy and safe workplace. Many regulations provide for aminimum medical surveillance program and specify manda-tory certain tests and procedures.

The occupational medicine physician and the occupa-tional health nurse should be familiar with all jobs, materi-als, and processes used. An occasional workplace inspectionby the medical team enables them to suggest protectivemeasures and aids them in recommending placement ofemployees in jobs best suited to their physical capabilities.(See discussion of the Americans with Disabilities Act inChapter 26, The Occupational Health Nurse.)

Determining the work-relatedness of disease is anothertask for the occupational medicine physician. The industrialhygienist provides information about the manufacturingoperations and work environment of a company to the med-ical department as well. In many cases it is extremely diffi-cult to differentiate between the symptoms of occupationaland nonoccupational disease. The industrial hygienist sup-plies information on the work operations and their associ-ated hazards and enables the medical department to correlatethe employee’s condition and symptoms with potentialworkplace health hazards.

The employee plays a major role in the occupationalhealth and safety program. Employees are excellent sourcesof information on work processes and procedures and thehazards of their daily operations. Industrial hygienists bene-fit from this source of information and often obtain innova-tive suggestions for controlling hazards.

The safety and health committee provides a forum forsecuring the cooperation, coordination, and exchange ofideas among those involved in the health and safety pro-gram. It provides a means of involving employees in the pro-gram. The typical functions of the safety and healthcommittee include, among others, to examine companysafety and health issues and recommend policies to man-agement, conduct periodic workplace inspections, and eval-uate and promote interest in the health and safety program.Joint labor–management safety and health committees are

often used where employees are represented by a union. Thecommittee meetings also present an opportunity to discusskey industrial hygiene program concerns and to formulateappropriate policies.

FEDERAL REGULATIONS Before 1970, government regulation of health and safetymatters was largely the concern of state agencies. There waslittle uniformity in codes and standards or in the applicationof these standards. Almost no enforcement proceduresexisted.

On December 29, 1970, the Occupational Safety andHealth Act, known as the OSHAct, was enacted by Con-gress. Its purpose was to “assure so far as possible every work-ing man and woman in the nation safe and healthfulworking conditions and to preserve our human resources.”The OSHAct sets out two duties for employers: ➣ Each employer shall furnish to each employee a place of

employment, which is free from recognized hazards thatare causing or are likely to cause death or serious harm totheir employees.

➣ Each employer shall comply with occupational safetyand health standards under the Act.

For employees, the OSHAct states that “Each employeeshall comply with occupational safety and health standardsand all rules, regulations, and orders issued pursuant to theAct which are applicable to his own actions and conduct.”

The Occupational Safety and Health Administration(OSHA) came into official existence on April 28, 1971, thedate the OSHAct became effective. It is housed within theU.S. Department of Labor. The OSHAct also establishedthe National Institute for Occupational Safety and Health(NIOSH), which is housed within the Centers for DiseaseControl and Prevention (CDC). The CDC is part of theU.S. Public Health Service.

OSHA was empowered to promulgate safety and healthstandards with technical advice from NIOSH. OSHA isempowered to enter workplaces to investigate alleged viola-tions of these standards and to perform routine inspections.Formal complaints of standards violations may be made byemployees or their representatives. The OSHAct also givesOSHA the right to issue citations and penalties, provide foremployee walkarounds or interview of employees during theinspection, require employers to maintain accurate recordsof exposures to potentially hazardous materials, and toinform employees of the monitoring results. OSHA is alsoempowered to provide up to 50/50 funding with states thatwish to establish state OSHA programs that are at least aseffective as the federal program. As of this date, there are 23approved state plans and approved plans from Puerto Ricoand the Virgin Islands.

NIOSH is the principal federal agency engaged in occu-pational health and safety research. The agency is responsi-ble for identifying hazards and making recommendations for


6

regulations. These recommendations are called Recom-mended Exposure Limits (RELs). NIOSH also issues criteriadocuments and health hazard alerts on various hazards and isresponsible for testing and certifying respiratory protectiveequipment.

Part of NIOSH research takes place during activitiescalled Health Hazard Evaluations. These are on-the-jobinvestigations of reported worker exposures that are carriedout in response to a request by either the employer or theemployee or employee representative. In addition to its ownresearch program, NIOSH also funds supportive researchactivities at a number of universities, colleges, and privatefacilities.

NIOSH has training grant programs in colleges and uni-versities across the nation. These are located at designatedEducation and Research Centers (ERCs). ERCs train occu-pational medicine physicians, occupational health nurses,industrial hygienists, safety professionals, ergonomists, andothers in the safety and health field. They also provide con-tinuing professional education for practicing occupationalhealth and safety professionals. (See Chapter 28, Govern-ment Regulations, and Chapter 29, History of the FederalOccupational Safety and Health Administration, for a fulldiscussion of federal agencies and regulations.)

ENVIRONMENTAL FACTORS OR STRESSES The various environmental factors or stresses that can causesickness, impaired health, or significant discomfort in work-ers can be classified as chemical, physical, biological, orergonomic.

Chemical hazards. These arise from excessive airborne con-centrations of mists, vapors, gases, or solids in the form ofdusts or fumes. In addition to the hazard of inhalation, someof these materials may act as skin irritants or may be toxic byabsorption through the skin.

Physical hazards. These include excessive levels of nonion-izing radiation (see Chapter 10), ionizing radiation (seeChapter 11), noise (see Chapter 9), vibration, and extremesof temperature (see Chapter 12) and pressure.

Ergonomic hazards. These include improperly designedtools, work areas, or work procedures. Improper lifting orreaching, poor visual conditions, or repeated motions in anawkward position can result in accidents or illnesses in theoccupational environment. Designing the tools and the jobto fit the worker is of prime importance. Engineering andbiomechanical principles must be applied to eliminate haz-ards of this kind (see Chapter 13).

Biological hazards. These are any living organism or itsproperties that can cause an adverse response in humans.They can be part of the total environment or associated with

a particular occupation. Work-related illnesses due to biolog-ical agents have been widely reported, but in many work-places their presence and resultant illness are not wellrecognized. It is estimated that the population at risk foroccupational biohazards may be several hundred millionworkers worldwide (see Chapter 14).

Exposure to many of the harmful stresses or hazards listedcan produce an immediate response due to the intensity ofthe hazard, or the response can result from longer exposureat a lower intensity.

In certain occupations, depending on the duration andseverity of exposure, the work environment can produce sig-nificant subjective responses or strain. The energies and agentsresponsible for these effects are called environmental stresses.An employee is most often exposed to an intricate interplay ofmany stresses, not to a single environmental stress.

Chemical Hazards The majority of occupational health hazards arise frominhaling chemical agents in the form of vapors, gases, dusts,fumes, and mists, or by skin contact with these materials.The degree of risk of handling a given substance depends onthe magnitude and duration of exposure. (See Chapter 15,Evaluation, for more details.)

To recognize occupational factors or stresses, a health andsafety professional must first know about the chemicals used asraw materials and the nature of the products and by-productsmanufactured. This sometimes requires great effort. Therequired information can be obtained from the Material SafetyData Sheet (MSDS) (Figure 1–2) that must be supplied by thechemical manufacturer or importer for all hazardous materialsunder the OSHA hazard communication standard. TheMSDS is a summary of the important health, safety, and tox-icological information on the chemical or the mixture ingredi-ents. Other stipulations of the hazard communicationstandard require that all containers of hazardous substances inthe workplace be labeled with appropriate warning and iden-tification labels. See Chapter 28, Government Regulations,and Chapter 29, History of the Federal Occupational Safetyand Health Administration, for further discussion of the haz-ard communication standard.

If the MSDS or the label does not give complete infor-mation but only trade names, it may be necessary to contactthe manufacturer to obtain this information.

Many industrial materials such as resins and polymers arerelatively inert and nontoxic under normal conditions of use,but when heated or machined, they may decompose to formhighly toxic by-products. Information about these hazardousproducts and by-products must also be included in the com-pany’s hazard communication program.

Breathing of some materials can irritate the upper res-piratory tract or the terminal passages of the lungs and theair sacs, depending upon the solubility of the material. Con-tact of irritants with the skin surface can produce variouskinds of dermatitis.


7

The presence of excessive amounts of biologically inertgases can dilute the atmospheric oxygen below the levelrequired to maintain the normal blood saturation value foroxygen and disturb cellular processes. Other gases andvapors can prevent the blood from carrying oxygen to thetissues or interfere with its transfer from the blood to the tis-sue, thus producing chemical asphyxia or suffocation. Car-bon monoxide and hydrogen cyanide are examples ofchemical asphyxiants.

Some substances may affect the central nervous systemand brain to produce narcosis or anesthesia. In varyingdegrees, many solvents have these effects. Substances areoften classified, according to the major reaction they pro-duce, as asphyxiants, systemic toxins, pneumoconiosis- producing agents, carcinogens, irritant gases, and so on.

SOLVENTSThis section discusses some general hazards arising from theuse of solvents; a more detailed description is given in Chap-ter 7, Gases, Vapors, and Solvents.

Solvent vapors enter the body mainly by inhalation,although some skin absorption can occur. The vapors areabsorbed from the lungs into the blood and are distributedmainly to tissues with a high content of fat and lipids, such asthe central nervous system, liver, and bone marrow. Solventsinclude aliphatic and aromatic hydrocarbons, alcohols, alde-hydes, ketones, chlorinated hydrocarbons, and carbon disulfide.

Occupational exposure can occur in many different pro-cesses, such as the degreasing of metals in the machine indus-try and the extraction of fats or oils in the chemical or foodindustry, dry cleaning, painting, and the plastics industry.

The widespread industrial use of solvents presents a majorproblem to the industrial hygienist, the safety professional,and others responsible for maintaining a safe, healthfulworking environment. Getting the job done using solventswithout hazard to employees or property depends on theproper selection, application, handling, and control of sol-vents and an understanding of their properties.

A working knowledge of the physical properties, nomen-clature, and effects of exposure is absolutely necessary inmaking a proper assessment of a solvent exposure. Nomen-clature can be misleading. For example, benzine is some-times mistakenly called benzene, a completely differentsolvent. Some commercial grades of benzine may containbenzene as a contaminant.

Use the information on the MSDS (Figure 1–2) or themanufacturer’s label for the specific name and compositionof the solvents involved.

The severity of a hazard in the use of organic solvents andother chemicals depends on the following factors: ➣ How the chemical is used ➣ Type of job operation, which determines how the work-

ers are exposed ➣ Work pattern ➣ Duration of exposure

➣ Operating temperature ➣ Exposed liquid surface ➣ Ventilation rates ➣ Evaporation rate of solvent ➣ Pattern of airflow ➣ Concentration of vapor in workroom air ➣ Housekeeping

The hazard is determined not only by the toxicity of thesolvent or chemical itself but by the conditions of its use(who, what, how, where, and how long).

The health and safety professional can obtain much valu-able information by observing the manner in which healthhazards are generated, the number of people involved, andthe control measures in use.

After the list of chemicals and physical conditions towhich employees are exposed has been prepared, determinewhich of the chemicals or agents may result in hazardousexposures and need further study.

Dangerous materials are chemicals that may, under spe-cific circumstances, cause injury to persons or damage toproperty because of reactivity, instability, spontaneousdecomposition, flammability, or volatility. Under this defi-nition, we will consider substances, mixtures, or compoundsthat are explosive, corrosive, flammable, or toxic.

Explosives are substances, mixtures, or compounds capa-ble of entering into a combustion reaction so rapidly andviolently as to cause an explosion.

Corrosives are capable of destroying living tissue andhave a destructive effect on other substances, particularly oncombustible materials; this effect can result in a fire orexplosion.

Flammable liquids are liquids with a flash point of 100 F(38 C) or less, although those with higher flash points can beboth combustible and dangerous.

Toxic chemicals are gases, liquids, or solids that, throughtheir chemical properties, can produce injurious or lethaleffects on contact with body cells.

Oxidizing materials are chemicals that decompose readilyunder certain conditions to yield oxygen. They may cause afire in contact with combustible materials, can react violentlywith water, and when involved in a fire can react violently.

Dangerous gases are those that can cause lethal or injuri-ous effects and damage to property by their toxic, corrosive,flammable, or explosive physical and chemical properties.

Storage of dangerous chemicals should be limited to oneday’s supply, consistent with the safe and efficient operationof the process. The storage should comply with applicablelocal laws and ordinances. An approved storehouse shouldbe provided for the main supply of hazardous materials.

For hazardous materials, MSDSs can be consulted fortoxicological information. The information is useful to themedical, purchasing, managerial, engineering, and healthand safety departments in setting guidelines for safe use ofthese materials. This information is also very helpful in anemergency. The information should cover materials actually


8


9

Figure 1–2. Material Safety Data Sheet. Its format meets the requirements of the federal hazard communication standard.(Continues)


10

Figure 1–2. (Continued)

in use and those that may be contemplated for early futureuse. Possibly the best and earliest source of information con-cerning such materials is the purchasing agent. Thus, a closeliaison should be set up between the purchasing agent andhealth and safety personnel so that early information is avail-able concerning materials in use and those to be ordered, andto ensure that MSDSs are received and reviewed for all haz-ardous substances.

TOXICITY VERSUS HAZARDThe toxicity of a material is not synonymous with its hazard.Toxicity is the capacity of a material to produce injury orharm when the chemical has reached a sufficient concentra-tion at a certain site in the body. Hazard is the probabilitythat this concentration in the body will occur. This degree ofhazard is determined by many factors or elements. (SeeChapter 6, Industrial Toxicology.)

The key elements to be considered when evaluating ahealth hazard are as follows: ➣ What is the route of entry of the chemical into the body?➣ How much of the material must be in contact with a

body cell and for how long to produce injury? ➣ What is the probability that the material will be absorbed

or come in contact with body cells? ➣ What is the rate of generation of airborne contaminants? ➣ What control measures are in place?

The effects of exposure to a substance depend on dose,rate, physical state of the substance, temperature, site ofabsorption, diet, and general state of a person’s health.

Physical Hazards Problems caused by such things as noise, temperatureextremes, ionizing radiation, nonionizing radiation, andpressure extremes are physical stresses. It is important thatthe employer, supervisor, and those responsible for safety andhealth be alert to these hazards because of the possible imme-diate or cumulative effects on the health of employees.

NOISENoise (unwanted sound) is a form of vibration conductedthrough solids, liquids, or gases. The effects of noise onhumans include the following:➣ Psychological effects (noise can startle, annoy, and dis-

rupt concentration, sleep, or relaxation) ➣ Interference with speech communication and, as a con-

sequence, interference with job performance and safety ➣ Physiological effects (noise-induced hearing loss, or aural

pain when the exposure is severe)

Damage risk criteria. If the ear is subjected to high levels ofnoise for a sufficient period of time, some loss of hearingmay occur. A number of factors can influence the effect ofthe noise exposure: ➣ Variation in individual susceptibility ➣ Total energy of the sound

➣ Frequency distribution of the sound ➣ Other characteristics of the noise exposure, such as

whether it is continuous, intermittent, or made up of aseries of impacts

➣ Total daily duration of exposure ➣ Length of employment in the noise environment

Because of the complex relationships of noise and expo-sure time to threshold shift (reduction in hearing level) andthe many contributory causes, establishing criteria for pro-tecting workers against hearing loss is difficult. However, cri-teria have been developed to protect against hearing loss inthe speech-frequency range. These criteria are known as theThreshold Limit Values for Noise. (See Chapter 9, IndustrialNoise, and Appendix B, The ACGIH Threshold Limit Val-ues and Biological Exposure Indices, for more details.)

There are three nontechnical guidelines to determinewhether the work area has excessive noise levels:➣ If it is necessary to speak very loudly or shout directly

into the ear of a person in order to be understood, it ispossible that the exposure limit for noise is beingexceeded. Conversation becomes difficult when the noiselevel exceeds 70 decibels (dBA).

➣ If employees say that they have heard ringing noises intheir ears at the end of the workday, they may be exposedto too much noise.

➣ If employees complain that the sounds of speech ormusic seem muffled after leaving work, but that theirhearing is fairly clear in the morning when they return towork, they may be exposed to noise levels that cause apartial temporary loss of hearing, which can become per-manent with repeated exposure.

Permissible levels. The criteria for hearing conservation,required by OSHAct in 29 CFR 1910.95, establishes the per-missible levels of harmful noise to which an employee maybe subjected. The permissible decibel levels and hours (dura-tion per day) are specified. For example, a noise level of 90dBA is permissible for eight hours, 95 dBA for four hours,etc. (See Chapter 9, Industrial Noise, for more details.)

The regulations stipulate that when employees are sub-jected to sound that exceeds the permissible limits, feasibleadministrative or engineering controls shall be used. If suchcontrols fail to reduce sound exposure within permissible lev-els, personal protective equipment must be provided andused to reduce sound levels to within permissible levels.

According to the Hearing Conservation Amendment to29 CFR 1910.95, in all cases when the sound levels exceed85 dBA on an eight-hour time-weighted average (TWA), acontinuing, effective hearing conservation program shall beadministered. The Hearing Conservation Amendment spec-ifies the essential elements of a hearing conservation pro-gram. (See Chapter 9, Industrial Noise, for a discussion ofnoise and OSHA noise regulations.)

Administering a hearing conservation program goesbeyond the wearing of earplugs or earmuffs. Such programs


11

can be complex, and professional guidance is essential forestablishing programs that are responsive to the need. Validnoise exposure information correlated with audiometric testsresults is needed to help health and safety and medical per-sonnel to make informed decisions about hearing conserva-tion programs.

The effectiveness of a hearing conservation programdepends on the cooperation of employers, employees, andothers concerned. Management’s responsibility in such aprogram includes noise measurements, initiation of noisecontrol measures, provision of hearing protection equip-ment, audiometric testing of employees to measure theirhearing levels (thresholds), and information and trainingprograms for employees.

The employee’s responsibility is to properly use the pro-tective equipment provided by management, and to observeany rules or regulations on the use of equipment in order tominimize noise exposure.

EXTREMES OF TEMPERATUREProbably the most elementary factor of environmental con-trol is control of the thermal environment in which peoplework. Extremes of temperature, or thermal stress, affect theamount of work people can do and the manner in whichthey do it. In industry, the problem is more often high tem-peratures rather than low temperatures. (More details on thissubject are given in Chapter 12, Thermal Stress.)

The body continuously produces heat through its meta-bolic processes. Because the body processes are designed tooperate only within a very narrow range of temperature, thebody must dissipate this heat as rapidly as it is produced if itis to function efficiently. A sensitive and rapidly acting set oftemperature-sensing devices in the body must also controlthe rates of its temperature-regulating processes. (Thismechanism is described in Chapter 3, The Skin and Occu-pational Dermatoses.)

Heat stress is a common problem, as are the problemspresented by a very cold environment. Evaluation of heatstress in a work environment is not simple. Considerablymore is involved than simply taking a number of air-temperature measurements and making decisions on thebasis of this information.

One question that must be asked is whether the tem-perature is merely causing discomfort or whether continuedexposure will cause the body temperature to fall below or riseabove safe limits. It is difficult for a person with only a clip-board full of data to interpret how another person actuallyfeels or is adversely affected.

People function efficiently only in a very narrow bodytemperature range, a core temperature measured deep insidethe body, not on the skin or at body extremities. Fluctuationsin core temperatures exceeding 2 F below or 3 F above thenormal core temperature of 99.6 F (37.6 C), which is 98.6 F(37 C) mouth temperature, impair performance markedly. Ifthis five-degree range is exceeded, a health hazard exists.

The body attempts to counteract the effects of high tem-perature by increasing the heart rate. The capillaries in theskin also dilate to bring more blood to the surface so that therate of cooling is increased. Sweating is an important factorin cooling the body.

Heatstroke is caused by exposure to an environment inwhich the body is unable to cool itself sufficiently. Heat-stroke is a much more serious condition than heat cramps orheat exhaustion. An important predisposing factor is exces-sive physical exertion or moderate exertion in extreme heatconditions. The method of control is to reduce the temper-ature of the surroundings or to increase the ability of thebody to cool itself, so that body temperature does not rise.In heatstroke, sweating may cease and the body temperaturecan quickly rise to fatal levels. It is critical to undertakeemergency cooling of the body even while medical help is onthe way. Studies show that the higher the body temperatureon admission to emergency rooms, the higher the fatalityrate. Heatstroke is a life-threatening medical emergency.

Heat cramps can result from exposure to high temper-ature for a relatively long time, particularly if accompaniedby heavy exertion, with excessive loss of salt and moisturefrom the body. Even if the moisture is replaced by drinkingplenty of water, an excessive loss of salt can cause heatcramps or heat exhaustion.

Heat exhaustion can also result from physical exertion ina hot environment. Its signs are a mildly elevated tem-perature, pallor, weak pulse, dizziness, profuse sweating, andcool, moist skin.

ENVIRONMENTAL MEASUREMENTSIn many heat stress studies, the variables commonly meas-ured are work energy metabolism (often estimated ratherthan measured), air movement, air temperature, humidity,and radiant heat. See Chapter 12, Thermal Stress, for illus-trations and more details.

Air movement is measured with some type of ane-mometer and the air temperature with a thermometer, oftencalled a dry bulb thermometer.

Humidity, or the moisture content of the air, is generallymeasured with a psychrometer, which gives both dry bulband wet bulb temperatures. Using these temperatures andreferring to a psychrometric chart, the relative humidity canbe established.

The term wet bulb is commonly used to describe the tem-perature obtained by having a wet wick over the mercury-well bulb of an ordinary thermometer. Evaporation ofmoisture in the wick, to the extent that the moisture contentof the surrounding air permits, cools the thermometer to atemperature below that registered by the dry bulb. The com-bined readings of the dry bulb and wet bulb thermometersare then used to calculate percent relative humidity, absolutemoisture content of the air, and water vapor pressure.

Radiant heat is a form of electromagnetic energy similarto light but of longer wavelength. Radiant heat (from such


12

sources as red-hot metal, open flames, and the sun) has noappreciable heating effect on the air it passes through, but itsenergy is absorbed by any object it strikes, thus heating theperson, wall, machine, or whatever object it falls on. Protec-tion requires placing opaque shields or screens between theperson and the radiating surface.

An ordinary dry bulb thermometer alone will not measureradiant heat. However, if the thermometer bulb is fixed inthe center of a metal toilet float that has been painted dullblack, and the top of the thermometer stem protrudes out-side through a one-hole cork or rubber stopper, radiant heatcan be measured by the heat absorbed in this sphere. Thisdevice is known as a globe thermometer.

Heat loss. Conduction is an important means of heat losswhen the body is in contact with a good cooling agent, suchas water. For this reason, when people are immersed in coldwater, they become chilled much more rapidly and effec-tively than when exposed to air of the same temperature.

Air movement cools the body by convection: The moving airremoves the air film or the saturated air (which is formed veryrapidly by evaporation of sweat) and replaces it with a fresh airlayer capable of accepting more moisture from the skin.

Heat stress indices. The methods commonly used to esti-mate heat stress relate various physiological and envi-ronmental variables and end up with one number that thenserves as a guide for evaluating stress. For example, the effec-tive temperature index combines air temperature (dry bulb),humidity (wet bulb), and air movement to produce a singleindex called an effective temperature.

Another index is the wet bulb globe temperature(WBGT). The numerical value of the WBGT index is cal-culated by the following equations.

Indoors or outdoors with no solar loads:WBGTin = 0.7 Tnwb + 0.3 Tgt

Outdoors with solar load: WBGTout = 0.7 Tnwb + 0.2 Tgt + 0.1 Tdb

whereTnwb = natural wet bulb temperature Tgt = globe temperature Tdb = dry bulb temperature

In its Criteria Document on Hot Environments (see Bib-liography), NIOSH states that when impermeable clothingis worn, the WBGT should not be used because evaporativecooling would be limited. The WBGT combines the effectsof humidity and air movement, air temperature and radia-tion, and air temperature. It has been successfully used forenvironmental heat stress monitoring at military camps tocontrol heat stress casualties. The measurements are few andeasy to make; the instrumentation is simple, inexpensive,and rugged; and the calculations are straightforward. It is

also the index used in the ACGIH Threshold Limit Values(TLVs®) for Chemical Substances and Physical Agents and Bio-logical Exposure Indices (BEIs®) book (see Appendix B). TheACGIH recommends TLVs for continuous work in hot envi-ronments as well as when 25, 50, or 75 percent of each work-ing hour is at rest. Regulating allowable exposure time in theheat is a viable technique for permitting necessary work tocontinue under heat-stress conditions that would be intoler-able for continuous exposure. The NIOSH criteria docu-ment also contains a complete recommended heat stresscontrol program including work practices.

Work practices include acclimation periods, work and restregimens, distribution of work load with time, regular breaksof a minimum of one per hour, provision for water intake,protective clothing, and application of engineering controls.Experience has shown that workers do not stand a hot jobvery well at first, but develop tolerance rapidly through accli-mation and acquire full endurance in a week to a month.(For more details, see Chapter 12, Thermal Stress, and theNIOSH criteria document.)

COLD STRESSGenerally, the answer to a cold work area is to supply heatwhere possible, except for areas that must be cold, such asfood storage areas.

General hypothermia is an acute problem resulting fromprolonged cold exposure and heat loss. If an individualbecomes fatigued during physical activity, he or she will bemore prone to heat loss, and as exhaustion approaches, sud-den vasodilation (blood vessel dilation) occurs with resultantrapid loss of heat.

Cold stress is proportional to the total thermal gradientbetween the skin and the environment because this gradientdetermines the rate of heat loss from the body by radiationand convection. When vasoconstriction (blood vessel con-striction) is no longer adequate to maintain body heat bal-ance, shivering becomes an important mechanism forincreasing body temperature by causing metabolic heat pro-duction to increase to several times the resting rate.

General physical activity increases metabolic heat. Withclothing providing the proper insulation to minimize heatloss, a satisfactory microclimate can be maintained. Onlyexposed body surfaces are likely to be excessively chilled andfrostbitten. If clothing becomes wet either from contact withwater or due to sweating during intensive physical work, itscold-insulating property is greatly diminished.

Frostbite occurs when the skin tissues freeze. Theoreti-cally, the freezing point of the skin is about 30 F (1 C); how-ever, with increasing wind velocity, heat loss is greater andfrostbite occurs more rapidly. Once started, freezing pro-gresses rapidly. For example, if the wind velocity reaches 20mph, exposed flesh can freeze within about 1 minute at 14F (10 C). Furthermore, if the skin comes in direct contactwith objects whose surface temperature is below the freezingpoint, frostbite can develop at the point of contact despite


13

warm environmental temperatures. Air movement is moreimportant in cold environments than in hot because thecombined effect of wind and temperature can produce acondition called windchill. The windchill index should beconsulted by everyone facing exposure to low temperatureand strong winds. (See Chapter 12, Thermal Stress.)

IONIZING RADIATIONA brief description of ionizing radiation hazards is given inthis section; for a complete description, see Chapter 10, Ion-izing Radiation.

To understand a little about ionization, recall that thehuman body is made up of various chemical compoundsthat are in turn composed of molecules and atoms. Eachatom has a nucleus with its own outer system of electrons.

When ionization of body tissues occurs, some of the electronssurrounding the atoms are forcibly ejected from their orbits. Thegreater the intensity of the ionizing radiation, the more ions arecreated and the more physical damage is done to the cells.

Light consisting of electromagnetic radiation from thesun that strikes the surface of the earth is very similar to x-rays and gamma-radiation; it differs only in wavelengthand energy content. (See description in Chapter 11, Non-ionizing Radiation.) However, the energy level of sunlightat the earth’s surface is too low to disturb orbital electrons,so sunlight is not considered ionizing even though it hasenough energy to cause severe skin burns over a period oftime.

The exact mechanism of the manner in which ionizationaffects body cells and tissue is complex. At the risk of over-simplifying some basic physical principles and ignoring oth-ers, the purpose of this section is to present enoughinformation so the health and safety professional will recog-nize the problems involved and know when to call on healthphysicists or radiation safety experts for help.

At least three basic factors must be considered in such anapproach to radiation safety: ➣ Radioactive materials emit energy that can damage living

tissue. ➣ Different kinds of radioactivity present different kinds of

radiation safety problems. The types of ionizing radia-tion we will consider are alpha-, beta-, x-ray, andgamma-radiation, and neutrons.

➣ Radioactive materials can be hazardous in two differentways. Certain materials can be hazardous even whenlocated some distance away from the body; these areexternal hazards. Other types are hazardous only whenthey get inside the body through breathing, eating, orbroken skin. These are called internal radiation hazards.

Instruments are available for evaluating possible radiationhazards. Meters or other devices are used for measuring radi-ation levels and doses.

Kinds of radioactivity. The five kinds of radioactivity thatare of concern are alpha, beta, x-ray, gamma, and neutron.

The first four are the most important because neutronsources usually are not used in ordinary manufacturingoperations.

Of the five types of radiation mentioned, alpha-particlesare the least penetrating. They do not penetrate thin barri-ers. For example, paper, cellophane, and skin stop alpha-particles.

Beta-radiation has considerably more penetrating powerthan alpha radiation. A quarter of an inch of aluminum canstop the more energetic betas. Virtually everyone is familiarwith the penetrating ability of x rays and the fact that a bar-rier such as concrete or lead is required to stop them.

Gamma-rays are, for all practical purposes, the same as xrays and require the same kinds of heavy shielding materials.

Neutrons are very penetrating and have characteristicsthat make it necessary to use shielding materials of highhydrogen atom content rather than high mass alone.

Although the type of radiation from one radioactivematerial may be the same as that emitted by several otherdifferent radioactive materials, there may be a wide variationin energies.

The amount of energy a particular kind of radioactivematerial possesses is defined in terms of MeV (million elec-tron volts); the greater the number of MeV, the greater theenergy. Each radioactive material emits its own particularkinds of radiation, with energy measured in terms of MeV.

External versus internal hazards. Radioactive materialsthat emit x-rays, gamma-rays, or neutrons are external haz-ards. In other words, such materials can be located some dis-tance from the body and emit radiation that producesionization (and thus damage) as it passes through the body.Control by limiting exposure time, working at a safe dis-tance, use of barriers or shielding, or a combination of allthree is required for adequate protection against externalradiation hazards.

As long as a radioactive material that emits only alpha-particles remains outside the body, it will not cause trouble.Internally, it is a hazard because the ionizing ability of alphaparticles at very short distances in soft tissue makes them averitable bulldozer. Once inside the body—in the lungs,stomach, or an open wound, for example—there is no thicklayer of skin to serve as a barrier and damage results. Alpha-emitting radioactive materials that concentrate as persistingdeposits in specific parts of the body are considered veryhazardous.

Beta-emitters are generally considered an internal hazardalthough they also can be classed as an external hazardbecause they can produce burns when in contact with theskin. They require the same precautions as do alpha-emittersif there is a chance they can become airborne. In addition,some shielding may be required.

Measuring ionizing radiation. Many types of meters areused to measure various kinds of ionizing radiation. These


14

meters must be accurately calibrated for the type of radiationthey are designed to measure.

Meters with very thin windows in the probes can be usedto check for alpha-radiation. Geiger-Mueller and ionizationchamber-type instruments are used for measuring beta-,gamma-, and x-radiation. Special types of meters are avail-able for measuring neutrons.

Devices are available that measure accumulated amounts(doses) of radiation. Film badges are used as dosimeters torecord the amount of radiation received from beta-, x-ray, orgamma-radiation and special badges are available to recordneutron radiation.

Film badges are worn by a worker continuously duringeach monitoring period. Depending on how they are worn,they allow an estimate of an accumulated dose of radiationto the whole body or to just a part of the body, such as ahand or arm.

Alpha-radiation cannot be measured with film badgesbecause alpha-particles do not penetrate the paper that mustbe used over the film emulsion to exclude light. (For moredetails on measurement and government regulations for ion-izing radiation, see Chapter 10, Ionizing Radiation.)

NONIONIZING RADIATIONThis is a form of electromagnetic radiation with varyingeffects on the body, depending largely on the wavelength ofthe radiation involved. In the following paragraphs, inapproximate order of decreasing wavelength and increasingfrequency, are some hazards associated with different regionsof the nonionizing electromagnetic radiation spectrum.Nonionizing radiation is covered in detail by OSHAct regu-lations 29 CFR 1910.97, and in Chapter 11, NonionizingRadiation.

Low frequency. Longer wavelengths, including powerlinetransmission frequencies, broadcast radio, and shortwaveradio, can produce general heating of the body. The healthhazard from these kinds of radiation is very small, however,because it is unlikely that they would be found in intensitiesgreat enough to cause significant effect. An exception can befound very close to powerful radio transmitter aerials.

Microwaves are found in radar, communications, sometypes of cooking, and diathermy applications. Microwaveintensities may be sufficient to cause significant heating oftissues.

The effect is related to wavelength, power intensity, andtime of exposure. Generally, longer wavelengths produce agreater penetration and temperature rise in deeper tissuesthan shorter wavelengths. However, for a given power inten-sity, there is less subjective awareness to the heat from longerwavelengths than there is to the heat from shorter wave-lengths, because of the absorption of the longer wavelengthradiation beneath the body’s surface.

An intolerable rise in body temperature, as well as local-ized damage to specific organs, can result from an exposure

of sufficient intensity and time. In addition, flammable gasesand vapors can ignite when they are inside metallic objectslocated in a microwave beam.

Infrared radiation does not penetrate below the superfi-cial layer of the skin, so its only effect is to heat the skin andthe tissues immediately below it. Except for thermal burns,the health hazard of exposure to low-level conventionalinfrared radiation sources is negligible. (For information onpossible damage to the eye, consult Chapter 11, Nonioniz-ing Radiation.)

Visible radiation, which is about midway in the elec-tromagnetic spectrum, is important because it can affectboth the quality and accuracy of work. Good lighting condi-tions generally result in increased product quality with lessspoilage and increased production.

Lighting should be bright enough for easy and efficientsight, and directed so that it does not create glare. Illumina-tion levels and brightness ratios recommended for man-ufacturing and service industries are published by theIlluminating Engineering Society. (See Chapter 11, Nonion-izing Radiation, for further information.)

One of the most objectionable features of lighting is glare(brightness in the field of vision that causes discomfort orinterferes with seeing). The brightness can be caused byeither direct or reflected light. To prevent glare, the source oflight should be kept well above the line of vision or shieldedwith opaque or translucent material.

Almost as problematic is an area of excessively highbrightness in the visual field. A highly reflective white paperin the center of a dark, nonreflecting surface or a brightlyilluminated control handle on a dark or dirty machine aretwo examples.

To prevent such conditions, keep surfaces uniformly lightor dark with little difference in surface reflectivity. Colorcontrasts are acceptable, however.

Although it is generally best to provide even, shadow-freelight, some jobs require contrast lighting. In these cases, keepthe general (or background) light well diffused and glarelessand add a supplementary source of light that casts shadowswhere needed.

Ultraviolet radiation in industry can be found aroundelectrical arcs, and such arcs should be shielded by materialsopaque to ultraviolet. The fact that a material can be opaqueto ultraviolet has no relation to its opacity to other parts ofthe spectrum. Ordinary window glass, for instance, is almostcompletely opaque to the ultraviolet in sunlight althoughtransparent to the visible wavelengths. A piece of plastic dyeda deep red-violet may be almost entirely opaque in the visible part of the spectrum and transparent in the near-ultraviolet spectrum.

Electric welding arcs and germicidal lamps are the mostcommon strong producers of ultraviolet radiation in indus-try. The ordinary fluorescent lamp generates a good deal ofultraviolet inside the bulb, but it is essentially all absorbed bythe bulb and its coating.


15

The most common exposure to ultraviolet radiation isfrom direct sunlight, and a familiar result of overexposure—one that is known to all sunbathers—is sunburn. Most peo-ple are familiar with certain compounds and lotions thatreduce the effects of the sun’s rays, but many are unawarethat some industrial materials, such as cresols, make the skinespecially sensitive to ultraviolet rays. After exposure tocresols, even a short exposure in the sun usually results in asevere sunburn.

Lasers emit beams of coherent radiation of a single coloror wavelength and frequency, in contrast to conventionallight sources, which produce random, disordered light wavemixtures of various frequencies. The laser (an acronym forlight amplification by stimulated emission of radiation) ismade up of light waves that are nearly parallel to each other,all traveling in the same direction. Atoms are “pumped” fullof energy, and when they are stimulated to fall to a lowerenergy level, they give off radiation that is directed to pro-duce the coherent laser beam. (See Chapter 11, NonionizingRadiation, for more details.)

The maser, the laser’s predecessor, emits microwavesinstead of light. Some companies call their lasers “opticalmasers.” Because the laser is highly collimated (has a smalldivergence angle), it can have a large energy density in a nar-row beam. Direct viewing of the laser source or its reflectionsshould be avoided. The work area should contain no reflec-tive surface (such as mirrors or highly polished furniture)because even a reflected laser beam can be hazardous. Suit-able shielding to contain the laser beam should be provided.The OSHAct covers protection against laser hazards in itsconstruction regulations.

Biological effects. The eye is the organ that is most vulner-able to injury by laser energy because the cornea and lensfocus the parallel laser beam on a small spot on the retina.The fact that infrared radiation of certain lasers may not bevisible to the naked eye contributes to the potential hazard.

Lasers generating in the ultraviolet range of the electro-magnetic spectrum can produce corneal burns rather thanretinal damage, because of the way the eye handles ultravio-let light. (See Chapter 11, Nonionizing Radiation.)

Other factors that affect the degree of eye injury inducedby laser light are as follows: ➣ Pupil size (the smaller the pupil diameter, the less laser

energy reaches the retina) ➣ The ability of the cornea and lens to focus the incident

light on the retina ➣ The distance from the source of energy to the retina➣ The energy and wavelength of the laser ➣ The pigmentation of the eye of the subject ➣ The location on the retina where the light is focused ➣ The divergence of the laser light ➣ The presence of scattering media in the light path

A discussion of laser beam characteristics and protectiveeyewear can be found in Chapter 11.

EXTREMES OF PRESSUREIt has been recognized from the beginning of caisson work(work performed in a watertight structure) that peopleworking under pressures greater than normal atmosphericpressure are subject to various health effects. Hyperbaric(greater than normal pressure) environments are alsoencountered by divers who work under water, whether byholding the breath while diving, breathing from a self-contained underwater breathing apparatus (SCUBA), or bybreathing gas mixtures supplied by compression from thesurface.

Occupational exposures occur in caisson or tunnelingoperations, where a compressed gas environment is used toexclude water or mud and to provide support for structures.Humans can withstand large pressures if air has free access tolungs, sinuses, and the middle ear. Unequal distribution ofpressure can result in barotrauma, a kind of tissue damageresulting from expansion or contraction of gas spaces withinor adjacent to the body, which can occur either during com-pression (descent) or during decompression (ascent).

The teeth, sinuses, and ears are often affected by pressure dif-ferentials. For example, gas spaces adjacent to tooth roots or fill-ings may be compressed during descent. Fluid or tissue forcedinto these spaces can cause pain during descent or ascent. Sinusblockage caused by occlusion of the sinus aperture by inflamednasal mucosa prevents equalization of pressures.

Under some conditions of work at high pressure, the con-centration of carbon dioxide in the atmosphere can be con-siderably increased so that the carbon dioxide acts as anarcotic. Keeping the oxygen concentration high minimizesthis condition, but does not prevent it. The procedure is use-ful where the carbon dioxide concentration cannot be keptat a proper level.

Decompression sickness, commonly called the bends,results from the release of nitrogen bubbles into the circu-lation and tissues during decompression. If the bubbleslodge at the joints and under muscles, they cause severecramps. To prevent this, decompression is carried out slowlyand by stages so that the nitrogen can be eliminated slowly,without forming bubbles.

Deep-sea divers are supplied with a mixture of heliumand oxygen for breathing, and because helium is an inertdiluent and less soluble in blood and tissue than is nitrogen,it presents a less formidable decompression problem.

One of the most common troubles encountered by work-ers under compressed air is pain and congestion in the earsfrom inability to ventilate the middle ear properly duringcompression and decompression. As a result, many workerssubjected to increased air pressures suffer from temporaryhearing loss; some have permanent hearing loss. This dam-age is believed to be caused by obstruction of the eustachiantubes, which prevents proper equalization of pressure fromthe throat to the middle ear.

The effects of reduced pressure on the worker are much thesame as the effects of decompression from a high pressure. If


16

pressure is reduced too rapidly, decompression sickness and eardisturbances similar to the diver’s conditions can result.

Ergonomic Hazards Ergonomics literally means the study or measurement ofwork. It is the application of human biological science inconjunction with the engineering sciences to achieve theoptimum mutual adjustment of people to their work, thebenefits being measured in terms of human efficiency andwell-being. The topic of ergonomics is covered briefly here.(For more details, see Chapter 13, Ergonomics.)

The ergonomics approach goes beyond productivity,health, and safety. It includes consideration of the total phys-iological and psychological demands of the job on theworker.

In the broad sense, the benefits that can be expected fromdesigning work systems to minimize physical stress on work-ers are as follows: ➣ Reduced incidence of repetitive motion disorders ➣ Reduced injury rate ➣ More efficient operation ➣ Fewer accidents ➣ Lower cost of operation ➣ Reduced training time ➣ More effective use of personnel

The human body can endure considerable discomfort andstress and can perform many awkward and unnatural move-ments for a limited period of time. However, when awkwardconditions or motions are continued for prolonged periods,they can exceed the worker’s physiological limitations. Toensure a continued high level of performance, work systemsmust be tailored to human capacities and limitations.

Ergonomics considers the physiological and psychologicalstresses of the task. The task should not require excessivemuscular effort, considering the worker’s age, sex, and stateof health. The job should not be so easy that boredom andinattention lead to unnecessary errors, material waste, andaccidents. Ergonomic stresses can impair the health and effi-ciency of the worker just as significantly as the more com-monly recognized environmental stresses.

The task of the design engineer and health and safety pro-fessional is to find the happy medium between “easy” and“difficult” jobs. In any human–machine system, there aretasks that are better performed by people than by machinesand, conversely, tasks that are better handled by machines.

Ergonomics deals with the interactions between humansand such traditional environmental elements as atmosphericcontaminants, heat, light, sound, and tools and equipment.People are the monitoring link of a human–machine envi-ronment system.

In any activity, a person receives and processes infor-mation, and then acts on it. The receptor function occurslargely through the sense organs of the eyes and the ear, butinformation can also be conveyed through the senses ofsmell, touch, or sensations of heat or cold. This information

is conveyed to the central mechanism of the brain and spinalcord, where the information is processed to arrive at a deci-sion. This can involve the integration of the information,which has already been stored in the brain, and decisions canvary from automatic responses to those involving a highdegree of reasoning and logic.

Having received the information and processed it, theindividual then takes action (control) as a result of the deci-sion, usually through muscular activity based on the skeletalframework of the body. When an individual’s activityinvolves the operation of a piece of equipment, the personoften forms part of a “closed-loop servosystem,” displayingmany of the feedback characteristics of such a system. Theperson usually forms the part of the system that makes deci-sions, and thus has a fundamental part to play in the effi-ciency of the system.

BIOMECHANICS–PHYSICAL DEMANDSBiomechanics can be a very effective tool in preventingexcessive work stress. Biomechanics means the mechanics ofbiological organisms. It deals with the functioning of thestructural elements of the body and the effects of externaland internal forces on the various parts of the body.

Cumulative effects of excessive ergonomic stress on theworker can, in an insidious and subtle manner, result inphysical illnesses and injuries such as “trigger finger,”tenosynovitis, bursitis, carpal tunnel syndrome, and othercumulative trauma disorders.

Cases of excessive fatigue and discomfort are, in manycases, forerunners of soreness and pain. By exerting a strongdistracting influence on a worker, these stresses can renderthe worker more prone to major accidents. Discomfort andfatigue tend to make the worker less capable of maintainingthe proper vigilance for the safe performance of the task.

Some of the principles of biomechanics can be illustratedby considering different parts of the human anatomy, such asthe hand.

Hand anatomy. The flexing action in the fingers is controlledby tendons attached to muscles in the forearm. The tendons,which run in lubricated sheaths, enter the hand through a tun-nel in the wrist formed by bones and ligaments (the carpaltunnel) and continue on to point of attachment to the differ-ent segments, or phalanges, of the fingers (Figure 1–3).

When the wrist is bent toward the little finger side, thetendons tend to bunch up on one side of the tunnel throughwhich they enter the hand. If an excessive amount of force iscontinuously applied with the fingers while the wrist isflexed, or if the flexing motion is repeated rapidly over a longperiod of time, the resulting friction can produce inflamma-tion of the tendon sheaths, or tenosynovitis. This can lead toa disabling condition called carpal tunnel syndrome. (SeeChapter 13, Ergonomics.)

The palm of the hand, which contains a network of nervesand blood vessels, should never be used as a hammer or


17

subjected to continued firm pressure. Repetitive or pro-longed pressure on the nerves and blood vessels in this areacan result in pain either in the palm itself or at any pointalong the nerve pathways up through the arm and shoulder.Other parts of the body, such as the elbow joints and shoul-ders, can become painful for similar reasons.

Mechanical vibration. A condition known to stone-cutters as “dead fingers” or “white fingers” (Raynaud’s phe-nomenon) occurs mainly in the fingers of the hand used toguide the cutting tool. The circulation in this handbecomes impaired, and when exposed to cold the fingersbecome white and without sensation, as though mildlyfrostbitten. The white appearance usually disappears whenthe fingers are warmed for some time, but a few cases aresufficiently disabling that the victims are forced to seekother types of work. In many instances both hands areaffected.

The condition has been observed in a number of otheroccupations involving the use of vibrating tools, such as theair hammers used for scarfing metal surfaces, the air chiselsfor chipping castings in the metal trades, and the chain sawsused in forestry. The injury is caused by vibration of the fin-gers as they grip the tools to guide them in performing their

tasks. The related damage to blood vessels can progress tonearly complete obstruction of the vessels.

Prevention should be directed at reducing the vibrationalenergy transferred to the fingers (perhaps by the use ofpadding) and by changing the energy and frequency of thevibration. Low frequencies, 25–75 hertz, are more damagingthan higher frequencies.

Lifting. The injuries resulting from manual handling ofobjects and materials make up a large proportion of all com-pensable injuries. This problem is of considerable concern tothe health and safety professional and represents an areawhere the biomechanical data relating to lifting and carryingcan be applied in the work layout and design of jobs thatrequire handling of materials. (For more details, see Chapter13, Ergonomics, and the Application Manual for the RevisedNIOSH Lifting Equation.)

The relevant data concerning lifting can be classified intotask, human, and environmental variables. ➣ Task variables

Location of object to be lifted Size of the object to be lifted Height from which and to which the object is lifted Frequency of lift Weight of object Working position

➣ Human variablesSex of worker Age of worker Training of workerPhysical fitness or conditioning of worker Body dimensions, such as height of the worker

➣ Environmental variables Extremes of temperature Humidity Air contaminants

Static work. Another very fatiguing situation encounteredin industry, which unfortunately is often overlooked, isstatic, or isometric, work. Because very little outward move-ment occurs, it seems that no muscular effort is involved.Often, however, such work generates more muscular fatiguethan work involving some outward movement. A crampedworking posture, for example, is a substantial source of staticmuscular loading.

In general, maintaining any set of muscles in a rigid,unsupported position for long periods of time results inmuscular strain. The blood supply to the contracted muscleis diminished, a local deficiency of oxygen can occur, andwaste products accumulate. Alternating static and dynamicwork, or providing support for partial relaxation of themember involved, alleviates this problem.

Armrests are usually needed in two types of situations. Oneis the case just mentioned—to relieve the isometric muscularwork involved in holding the arm in a fixed, unsupported


18

Figure 1–3. Diagram of hand anatomy.

position for long periods of time. The second case is where thearm is pressed against a hard surface such as the edge of abench or machine. The pressure on the soft tissues overlayingthe bones can cause bruises and pain. Padded armrests havesolved numerous problems of both types (see Figure 1–4).

WORKPLACE DESIGNRelating the physical characteristics and capabilities of theworker to the design of equipment and to the layout of theworkplace is another key ergonomic concept. When this isdone, the result is an increase in efficiency, a decrease inhuman error, and a consequent reduction in accident fre-quency. However, several different types of information areneeded: a description of the job, an understanding of thekinds of equipment to be used, a description of the kinds ofpeople who will use the equipment, and the biological char-acteristics of these people.

In general, the first three items—job, equipment, andusers—can be defined easily. The biological characteristics ofthe users, however, can often be determined satisfactorilyonly from special surveys that yield descriptive data onhuman body size and biomechanical abilities and limitations.

Anthropometric data. Anthropometric data consist of var-ious heights, lengths, and breadths used to establish the min-imum clearances and spatial accommodations, and thefunctional arm, leg, and body movements that are made bythe worker during the performance of the task.

BEHAVIORAL ASPECTS—MENTAL DEMANDSOne important aspect of industrial machine design directlyrelated to the safety and productivity of the worker is thedesign of displays and controls.

Design of displays. Displays are one of the most commontypes of operator input; the others include direct sensing andverbal or visual commands. Displays tell the operator whatthe machine is doing and how it is performing. Problems ofdisplay design are primarily related to the human senses.

A machine operator can successfully control equipmentonly to the extent that the operator receives clear, unam-biguous information, when needed on all pertinent aspectsof the task. Accidents, or operational errors, often occurbecause a worker has misinterpreted or was unable to obtaininformation from displays. Displays are usually visual,although they also can be auditory (for example, a warningbell rather than a warning light), especially when there isdanger of overloading the visual sensory channels.

Design of Controls. An operator must decide on the propercourse of action and manipulate controls to produce anydesired change in the machine’s performance. The efficiencyand effectiveness—that is, the safety with which controls canbe operated—depend on the extent to which information onthe dynamics of human movement (or biomechanics) has been

incorporated in their design. This is particularly true whenevercontrols must be operated at high speed, against large resist-ances, with great precision, or over long periods of time.

Controls should be designed so that rapid, accurate set-tings easily can be made without undue fatigue, therebyavoiding many accidents and operational errors. Becausethere is a wide variety of machine controls, ranging from thesimple on–off action of pushbuttons to very complex mech-anisms, advance analysis of the task requirements must bemade. On the basis of considerable experimental evidence, itis possible to recommend the most appropriate control andits desirable range of operation.

In general, the mechanical design of equipment must becompatible with the biological and psychological char-acteristics of the operator. The effectiveness of the human–machine combination can be greatly enhanced by treatingthe operator and the equipment as a unified system. Thus,the instruments should be considered as extensions of theoperator’s nervous and perceptual systems, the controls asextensions of the hands, and the feet as simple tools. Anycontrol that is difficult to reach or operate, any instrumentdial that has poor legibility, any seat that induces poor pos-ture or discomfort, or any obstruction of vision can contrib-ute directly to an accident or illness.

Biological Hazards Approximately 200 biological agents, such as infectiousmicroorganisms, biological allergens, and toxins, are knownto produce infections or allergenic, toxic, or carcinogenicreactions in workers. Most of the identified biohazardousagents belong to these groups:


19

Figure 1–4. Worker uses pads to keep her forearm off thesharp table edge.

➣ Microorganisms and their toxins (viruses, bacteria,fungi, and their products) resulting in infection, expo-sure, or allergy

➣ Arthropods (crustaceans, arachnids, insects) associatedwith bites or stings resulting in skin inflammation, sys-temic intoxication and transmission of infectious agents,or allergic response

➣ Allergens and toxins from higher plants, producing der-matitis, rhinitis, or asthma

➣ Protein allergens (such as urine, feces, hair, saliva, anddander) from vertebrate animals

Other groups with the potential to expose workers to biohaz-ards include lower plants other than fungi (lichen, liverworts,ferns) and invertebrate animals other than arthropods (parasitessuch as protozoa, Schistosoma) and roundworms (Ascaris).

Workers engaging in agricultural, medical, and laboratorywork have been identified as most at risk to occupationalbiohazards but many varied workplaces present the potentialfor such exposure. For example, at least 24 of the 150zoonotic diseases known worldwide are considered to be ahazard for agricultural workers in North America. Risk ofinfection varies with the type and species of animal and geo-graphic location. Disease may be contracted directly fromanimals, but more often it is acquired in the workplace envi-ronment. Controls include awareness of specific hazards, useof personal protective equipment, preventive veterinary care,worker education, and medical monitoring or prophylactictherapy, where appropriate.

The potential for exposure to occupational biohazardsexists in most work environments. The following are but afew examples in very diverse workplaces: ➣ Workers maintaining water systems can be exposed to

Legionella pneumophila and Naegleria spp. ➣ Workers associated with birds (parrots, parakeets,

pigeons) in pet shops, aviaries, or on construction andpublic works jobs near perching or nesting sites can beexposed to Chlamydia psittaci.

➣ Workers in wood processing facilities can be exposed toendotoxins, allergenic fungi growing on timber, andfungi causing deep mycoses.

➣ Sewage and compost workers can be exposed to enteric bac-teria, hepatitis A virus, infectious or endotoxin-producing bacteria, parasitic protozoa, and allergenic fungi.

➣ Health care workers, emergency responders, law enforce-ment officers, and morticians may be exposed to suchbloodborne pathogens as hepatitis B (HBV), hepatitis C(HCV), and the human immunodeficiency virus (HIV)in addition to other biological hazards. (See Chapter 14,Biological Hazards.)

BUILDING-RELATED ILLNESSES DUE TO BIOLOGICAL HAZARDSThe sources of biological hazards may be fairly obvious inoccupations associated with the handling of microorganisms,plants, and animals and in occupations involving contact withpotentially infected people. However, recognizing and identi-

fying biological hazards may not be as simple in other situa-tions such as office buildings and nonindustrial workplaces.Building-related illness (BRI) is a clinically diagnosed diseasein one or more building occupants, as distinguished from sick-building syndrome (SBS), in which building occupants’ non-specific symptoms cannot be associated with an identifiablecause. Certain BRI such as infectious and hypersensitivity dis-eases are clearly associated with biological hazards, but the roleof biological materials in SBS is not as well understood.

The conditions and events necessary to result in humanexposure to bioaerosols are the presence of a reservoir thatcan support the growth of microorganisms or allow accu-mulation of biological material, multiplication of con-taminating organisms or biological materials in the reservoir,generation of aerosols containing biological material, andexposure of susceptible workers. (See Chapter 14, BiologicalHazards, for a full discussion.)

INDUSTRIAL SANITATION—WATER SUPPLYThe requirements for sanitation and personal facilities arecovered in the OSHAct safety and health regulations 29CFR 1910, Subpart J—General Environmental Controls.The OSHAct regulations for carcinogens require special per-sonal health and sanitary facilities for employees workingwith potentially carcinogenic materials.

Potable water should be provided in workplaces whenneeded for drinking and personal washing, cooking, washingof foods or utensils, washing of food preparation premises,and personal service rooms.

Drinking fountain surfaces must be constructed of mate-rials impervious to water and not subject to oxidation. Thenozzle of the fountain must be located to prevent the returnof water in the jet or bowl to the nozzle orifice. A guard overthe nozzle prevents contact with the nozzle by the mouth ornose of people using the drinking fountain.

Potable drinking water dispensers must be designed andconstructed so that sanitary conditions are maintained; theymust be capable of being closed and equipped with a tap. Icethat comes in contact with drinking water must be made ofpotable water and maintained in a sanitary condition.Standing water in cooling towers and other air-moving sys-tems should be monitored for legionella bacteria. (See Chap-ter 14, Biological Hazards, for details.)

Outlets for nonpotable water, such as water for industrialor firefighting purposes, must be marked in a manner thatindicates clearly that the water is unsafe and is not to be usedas drinking water. Nonpotable water systems or systems car-rying any other nonpotable substance should be constructedso as to prevent backflow or backsiphonage.

HARMFUL AGENTS–ROUTE OF ENTRY In order to exert its toxic effect, a harmful agent must comeinto contact with a body cell and must enter the body viainhalation, skin absorption, or ingestion.


20

Chemical compounds in the form of liquids, gases, mists,dusts, fumes, and vapors can cause problems by inhalation(breathing), absorption (through direct contact with theskin), or ingestion (eating or drinking).

Inhalation Inhalation involves airborne contaminants that can beinhaled directly into the lungs and can be physically classi-fied as gases, vapors, and particulate matter including dusts,fumes, smokes, aerosols, and mists.

Inhalation, as a route of entry, is particularly importantbecause of the rapidity with which a toxic material can beabsorbed in the lungs, pass into the bloodstream, and reachthe brain. Inhalation is the major route of entry for haz-ardous chemicals in the work environment.

Absorption Absorption through the skin can occur quite rapidly if theskin is cut or abraded. Intact skin, however, offers a reason-ably good barrier to chemicals. Unfortunately, there aremany compounds that can be absorbed through intact skin.

Some substances are absorbed by way of the openings forhair follicles and others dissolve in the fats and oils of theskin, such as organic lead compounds, many nitro com-pounds, and organic phosphate pesticides. Compounds thatare good solvents for fats (such as toluene and xylene) alsocan be absorbed through the skin.

Many organic compounds, such as TNT, cyanides, andmost aromatic amines, amides, and phenols, can producesystemic poisoning by direct contact with the skin.

Ingestion In the workplace, people can unknowingly eat or drink harm-ful chemicals. Toxic compounds can be absorbed from thegastrointestinal tract into the blood. Lead oxide can causeserious problems if people working with this material areallowed to eat or smoke in work areas. Thorough washing isrequired both before eating and at the end of every shift.

Inhaled toxic dusts can also be ingested in hazardousamounts. If the toxic dust swallowed with food or saliva isnot soluble in digestive fluids, it is eliminated directlythrough the intestinal tract. Toxic materials that are readilysoluble in digestive fluids can be absorbed into the bloodfrom the digestive system.

It is important to study all routes of entry when evaluatingthe work environment—candy bars or lunches in the workarea, solvents being used to clean work clothing and hands, inaddition to airborne contaminants in working areas. (Formore details, see Chapter 6, Industrial Toxicology.)

TYPES OF AIRBORNE CONTAMINANTS There are precise meanings of certain words commonly usedin industrial hygiene. These must be used correctly in orderto understand the requirements of OSHAct regulations,

effectively communicate with other occupational health pro-fessionals, recommend or design and test appropriate engi-neering controls, and correctly prescribe personal protectiveequipment. For example, a fume respirator is worthless asprotection against gases or vapors. Too often, terms (such asgases, vapors, fumes, and mists) are used interchangeably.Each term has a definite meaning and describes a certainstate of matter.

States of Matter Matter is divided into dusts, fumes, smoke, aerosols, mists,gases, and vapors. These are discussed in the following sections.

DUSTSThese are solid particles generated by handling, crushing,grinding, rapid impact, detonation, and decrepitation(breaking apart by heating) of organic or inorganic materials,such as rock, ore, metal, coal, wood, and grain.

Dust is a term used in industry to describe airborne solidparticles that range in size from 0.1–25 µm in diameter (1µm = 0.0001 cm or 1/25,400 in.). Dusts more than 5 µm insize usually do not remain airborne long enough to presentan inhalation problem (see Chapter 8, Particulates).

Dust can enter the air from various sources, such as whena dusty material is handled (as when lead oxide is dumpedinto a mixer or talc is dusted on a product). When solidmaterials are reduced to small sizes in processes such asgrinding, crushing, blasting, shaking, and drilling, themechanical action of the grinding or shaking device suppliesenergy to disperse the dust.

Evaluating dust exposures properly requires knowledge ofthe chemical composition, particle size, dust concentrationin air, how it is dispersed, and many other factors describedhere. Although in the case of gases, the concentration thatreaches the alveolar sacs is nearly like the concentration inthe air breathed, this is not the case for aerosols or dust par-ticles. Large particles, more than 10 µm aerodynamic diam-eter, can be deposited through gravity and impaction in largeducts before they reach the very small sacs (alveoli). Only thesmaller particles reach the alveoli. (See Chapter 2, TheLungs, for more details.)

Except for some fibrous materials, dust particles mustusually be smaller than 5 µm in order to penetrate to thealveoli or inner recess of the lungs.

A person with normal eyesight can detect dust particles assmall as 50 µm in diameter. Smaller airborne particles can bedetected individually by the naked eye only when stronglight is reflected from them. Particles of dust of respirablesize (less than 10 µm) cannot be seen without the aid of amicroscope, but they may be perceived as a haze.

Most industrial dusts consist of particles that vary widelyin size, with the small particles greatly outnumbering thelarge ones. Consequently (with few exceptions), when dust isnoticeable in the air near a dusty operation, probably moreinvisible dust particles than visible ones are present. A


21

process that produces dust fine enough to remain suspendedin the air long enough to be breathed should be regarded ashazardous until it can be proved safe.

There is no simple one-to-one relationship between theconcentration of an atmospheric contaminant and durationof exposure and the rate of dosage by the hazardous agent tothe critical site in the body. For a given magnitude of atmos-pheric exposure to a potentially toxic particulate contami-nant, the resulting hazard can range from an insignificantlevel to one of great danger, depending on the toxicity of thematerial, the size of the inhaled particles, and other factorsthat determine their fate in the respiratory system.

FUMESThese are formed when the material from a volatilized solidcondenses in cool air. The solid particles that are formed makeup a fume that is extremely fine, usually less than 1.0 µm indiameter. In most cases, the hot vapor reacts with the air toform an oxide. Gases and vapors are not fumes, although theterms are often mistakenly used interchangeably.

Welding, metalizing, and other operations involvingvapors from molten metals may produce fumes; these maybe harmful under certain conditions. Arc welding volatilizesmetal vapor that condenses as the metal or its oxide in theair around the arc. In addition, the rod coating is partiallyvolatilized. These fumes, because they are extremely fine, arereadily inhaled.

Other toxic fumes, such as those formed when weldingstructures that have been painted with lead-based paints orwhen welding galvanized metal, can produce severe symp-toms of toxicity rather rapidly unless fumes are controlledwith effective local exhaust ventilation or the welder is pro-tected by respiratory protective equipment.

Fortunately, most soldering operations do not requiretemperatures high enough to volatilize an appreciableamount of lead. However, the lead in molten solder pots isoxidized by contact with air at the surface. If this oxide,often called dross, is mechanically dispersed into the air, itcan produce a severe lead-poisoning hazard.

In operations when lead dust may be present in air, suchas soldering or lead battery-making, preventing occupationalpoisoning is largely a matter of scrupulously clean house-keeping to prevent the lead oxide from becoming dispersedinto the air. It is customary to enclose melting pots, drossboxes, and similar operations, and to ventilate them ade-quately to control the hazard. Other controls may be neces-sary as well.

SMOKEThis consists of carbon or soot particles less than 0.1 µm insize, and results from the incomplete combustion of car-bonaceous materials such as coal or oil. Smoke generallycontains droplets as well as dry particles. Tobacco, forinstance, produces a wet smoke composed of minute tarrydroplets.

AEROSOLSThese are liquid droplets or solid particles of fine enoughparticle size to remain dispersed in air for a prolonged periodof time.

MISTSThese are suspended liquid droplets generated by condensa-tion of liquids from the vapor back to the liquid state or bybreaking up a liquid into a dispersed state, such as by splash-ing, foaming, or atomizing. The term mist is applied to afinely divided liquid suspended in the atmosphere. Examplesare the oil mist produced during cutting and grinding opera-tions, acid mists from electroplating, acid or alkali mists frompickling operations, paint spray mist in painting operations,and the condensation of water vapor to form a fog or rain.

GASESThese are formless fluids that expand to occupy the space orenclosure in which they are confined. Gases are a state ofmatter in which the molecules are unrestricted by cohesiveforces. Examples are arc-welding gases, internal combustionengine exhaust gases, and air.

VAPORSThese are the volatile form of substances that are normallyin the solid or liquid state at room temperature and pressure.Evaporation is the process by which a liquid is changed intothe vapor state and mixed with the surrounding atmosphere.Solvents with low boiling points volatilize readily at roomtemperature.

In addition to the definitions concerning states of matterthat are used daily by industrial hygienists, terms used todescribe degree of exposure include the following: ➣ ppm: parts of vapor or gases per million parts of air by

volume at room temperature and pressure ➣ mppcf: millions of particles of a particulate per cubic

foot of air ➣ mg/m3: milligrams of a substance per cubic meter of air ➣ f/cc: fibers of a substance per cubic centimeter of air

The health and safety professional recognizes that air con-taminants exist as a gas, dust, fume, mist, or vapor in theworkroom air. In evaluating the degree of exposure, themeasured concentration of the air contaminant is comparedto limits or exposure guidelines that appear in the publishedstandards on levels of exposure (see Appendix B).

Respiratory Hazards Airborne chemical agents that enter the lungs can passdirectly into the bloodstream and be carried to other parts ofthe body. The respiratory system consists of organs con-tributing to normal respiration or breathing. Strictly speak-ing, it includes the nose, mouth, upper throat, larynx,trachea, and bronchi (which are all air passages or airways)and the lungs, where oxygen is passed into the blood andcarbon dioxide is given off. Finally, it includes the


22

diaphragm and the muscles of the chest, which perform thenormal respiratory movements of inspiration and expiration.(See Chapter 2, The Lungs.)

All living cells of the body are engaged in a series of chem-ical processes; the sum total of these processes is called metab-olism. In the course of its metabolism, each cell consumesoxygen and produces carbon dioxide as a waste product.

Respiratory hazards can be broken down into two maingroups: ➣ Oxygen deficiency, in which the oxygen concentration

(or partial pressure of oxygen) is below the level con-sidered safe for human exposure

➣ Air that contains harmful or toxic contaminants

OXYGEN-DEFICIENT ATMOSPHERESEach living cell in the body requires a constant supply ofoxygen. Some cells are more dependent on a continuing oxy-gen supply than others. Some cells in the brain and nervoussystem can be injured or die after 4–6 min without oxygen.These cells, if destroyed, cannot be regenerated or replaced,and permanent changes and impaired functioning of thebrain can result from such damage. Other cells in the bodyare not as critically dependent on an oxygen supply becausethey can be replaced.

Normal air at sea level contains approximately 21 percentoxygen and 79 percent nitrogen and other inert gases. At sealevel and normal barometric pressure (760 mmHg or 101.3kPa), the partial pressure of oxygen would be 21 percent of760 mm, or 160 mm. The partial pressure of nitrogen andinert gases would be 600 mm (79 percent of 760 mm).

At higher altitudes or under conditions of reduced baro-metric pressure, the relative proportions of oxygen and nitro-gen remain the same, but the partial pressure of each gas isdecreased. The partial pressure of oxygen at the alveolar sur-face of the lung is critical because it determines the rate ofoxygen diffusion through the moist lung tissue membranes.

Oxygen-deficient atmospheres may exist in confinedspaces as oxygen is consumed by chemical reactions such asoxidation (rust, fermentation), replaced by inert gases such asargon, nitrogen, and carbon dioxide, or absorbed by poroussurfaces such as activated charcoal.

Deficiency of oxygen in the atmosphere of confinedspaces can be a problem in industry. For this reason, the oxy-gen content of any tank or other confined space (as well asthe levels of any toxic contaminants) should be measuredbefore entry is made. Instruments are commercially availablefor this purpose. (See Chapter 16, Air Sampling, Chapter 17,Direct-Reading Instruments for Gases, Vapors, and Particu-lates, and Chapter 22, Respiratory Protection, for moredetails.)

The first physiological signs of an oxygen deficiency(anoxia) are an increased rate and depth of breathing. Aworker should never enter or remain in areas where tests haveindicated oxygen deficiency without a supplied-air or self-contained respirator that is specifically approved by NIOSH

for those conditions. (See Chapter 22, Respiratory Protec-tion, for more details.)

Oxygen-deficient atmospheres can cause an inability tomove and a semiconscious lack of concern about the immi-nence of death. In cases of abrupt entry into areas containinglittle or no oxygen, the person usually has no warning symp-toms, immediately loses consciousness, and has no recollec-tion of the incident if rescued in time to be revived. Thesenses cannot be relied on to alert or warn a person of atmos-pheres deficient in oxygen.

Oxygen-deficient atmospheres can occur in tanks, vats,holds of ships, silos, mines, or in areas where the air may bediluted or displaced by asphyxiating levels of gases or vapors,or where the oxygen may have been consumed by chemicalor biological reactions.

Ordinary jobs involving maintenance and repair of sys-tems for storing and transporting fluids or entering tanks ortunnels for cleaning and repairs are controlled almostentirely by the immediate supervisor. The supervisor shouldbe particularly knowledgeable of all rules and precautions toensure the safety of those who work in such atmospheres.Safeguards should be meticulously observed.

For example, there should be a standard operating proce-dure for entering tanks. Such procedures should be consis-tent with OSHAct regulations and augmented by in-houseprocedures, which may enhance the basic OSHAct rules.The American National Standards Institute (ANSI) lists con-fined space procedures in its respiratory protection standardand NIOSH has also issued guidelines for work in confinedspaces including a criteria document for working in confinedspaces (see Bibliography). Even if a tank is empty, it mayhave been closed for some time and developed an oxygendeficiency through chemical reactions of residues left in thetank. It may be unsafe to enter without proper respiratoryprotection.

THE HAZARD OF AIRBORNE CONTAMINANTSInhaling harmful materials can irritate the upper respira-tory tract and lung tissue, or the terminal passages of thelungs and the air sacs, depending on the solubility of thematerial.

Inhalation of biologically inert gases can dilute the atmos-pheric oxygen below the normal blood saturation value anddisturb cellular processes. Other gases and vapors may pre-vent the blood from carrying oxygen to the tissues or inter-fere with its transfer from the blood to the tissue, producingchemical asphyxia.

Inhaled contaminants that adversely affect the lungs fallinto three general categories: ➣ Aerosols (particulates), which, when deposited in the

lungs, can produce either rapid local tissue damage,some slower tissue reactions, eventual disease, or physi-cal plugging

➣ Toxic vapors and gases that produce adverse reaction inthe tissue of the lungs


23

➣ Some toxic aerosols or gases that do not affect the lungtissue locally but pass from the lungs into the blood-stream, where they are carried to other body organs orhave adverse effects on the oxygen-carrying capacity ofthe blood cells

An example of an aerosol is silica dust, which causesfibrotic growth (scar tissue) in the lungs. Other harmfulaerosols are fungi found in sugar cane residues, producingbagassosis.

An example of the second type of inhaled contaminant ishydrogen fluoride, a gas that directly affects lung tissue. It isa primary irritant of mucous membranes, even causingchemical burns. Inhalation of this gas causes pulmonaryedema and direct interference with the gas transfer functionof the alveolar lining.

An example of the third type of inhaled contaminant iscarbon monoxide, a toxic gas passed into the bloodstreamwithout harming the lung. The carbon monoxide passesthrough the alveolar walls into the blood, where it ties up thehemoglobin so that it cannot accept oxygen, thus causingoxygen starvation. Cyanide gas has another effect—it pre-vents enzymatic utilization of molecular oxygen by cells.

Sometimes several types of lung hazards occur simultane-ously. In mining operations, for example, explosives releaseoxides of nitrogen. These impair the bronchial clearancemechanism so that coal dust (of the particle sizes associatedwith the explosions) is not efficiently cleansed from the lungs.

If a compound is very soluble—such as ammonia, sulfu-ric acid, or hydrochloric acid—it is rapidly absorbed in theupper respiratory tract and during the initial phases of expo-sure does not penetrate deeply into the lungs. Consequently,the nose and throat become very irritated.

Compounds that are insoluble in body fluids cause con-siderably less throat irritation than the soluble ones, but canpenetrate deeply into the lungs. Thus, a very serious hazardcan be present and not be recognized immediately because ofa lack of warning that the local irritation would otherwiseprovide. Examples of such compounds (gases) are nitrogendioxide and ozone. The immediate danger from these com-pounds in high concentrations is acute lung irritation or,possibly, chemical pneumonia.

There are numerous chemical compounds that do notfollow the general solubility rule. Such compounds are notvery soluble in water and yet are very irritating to the eyesand respiratory tract. They also can cause lung damage andeven death under certain conditions. (See Chapter 6, Indus-trial Toxicology.)

THRESHOLD LIMIT VALUES The ACGIH Threshold Limit Values® (TLVs®) are exposureguidelines established for airborne concentrations of manychemical compounds. The health and safety professional orother responsible person should understand somethingabout TLVs and the terminology in which their concentra-

tions are expressed. (See Chapter 15, Evaluation, Chapter 6,Industrial Toxicology, and Appendix B for more details.)

TLVs are airborne concentrations of substances and rep-resent conditions under which it is believed that nearly allworkers may be repeatedly exposed, day after day, withoutadverse effect. Control of the work environment is based onthe assumption that for each substance there is some safe ortolerable level of exposure below which no significantadverse effect occurs. These tolerable levels are calledThreshold Limit Values. In its Introduction, the ACGIHThreshold Limit Values (TLVs®) for Chemical Subtances andPhysical Agents and Biological Exposure Indices (BEIs®) statesthat because individual susceptibility varies widely, a smallpercentage of workers may experience discomfort fromsome substances at concentrations at or below the thresholdlimit. A smaller percentage may be affected more seriouslyby aggravation of a preexisting condition or by develop-ment of an occupational illness. Smoking may enhance thebiological effects of chemicals encountered in the workplaceand may reduce the body’s defense mechanisms againsttoxic substances.

Hypersusceptible individuals or those otherwise unusuallyresponsive to some industrial chemicals because of geneticfactors, age, personal habits (smoking and use of alcohol orother drugs), medication, or previous exposures may not beadequately protected from adverse health effects of chemicalsat concentrations at or below the threshold limits.

These limits are not fine lines between safe and dangerousconcentration, nor are they a relative index of toxicity. Theyshould not be used by anyone untrained in the discipline ofindustrial hygiene.

The copyrighted trademark Threshold Limit Value® refersto limits published by ACGIH. The TLVs are reviewed andupdated annually to reflect the most current information onthe effects of each substance assigned a TLV. (See AppendixB and the Bibliography of this chapter.)

The data for establishing TLVs come from animal studies,human studies, and industrial experience, and the limit maybe selected for several reasons. As mentioned earlier in thischapter, the TLV can be based on the fact that a substance isvery irritating to the majority of people exposed, or the factthat a substance is an asphyxiant. Still other reasons forestablishing a TLV for a given substance include the fact thatcertain chemical compounds are anesthetic or fibrogenic orcan cause allergic reactions or malignancies. Some additionalTLVs have been established because exposure above a certainairborne concentration is a nuisance.

The amount and nature of the information available forestablishing a TLV varies from substance to substance; con-sequently, the precision of the estimated TLV continues tobe subject to revision and debate. The latest documentationfor that substance should be consulted to assess the presentdata available for a given substance.

In addition to the TLVs set for chemical compounds,there are limits for physical agents such as noise,


24

radiofrequency/microwave radiation, segmental vibration,lasers, ionizing radiation, static magnetic fields, light, near-infrared radiation, subradiofrequency (≤ 30 kHz) magneticfields, subradiofrequency and static electric fields, ultravioletradiation, cold stress, and heat stress. There are also biologicalexposure indices (BEIs®). (See Chapter 9, Industrial Noise,Chapter 11, Nonionizing Radiation, and Appendix B.)

The ACGIH periodically publishes a documentation ofTLVs® in which it gives the data and information on whichthe TLV for each substance is based. This documentationcan be used to provide health and safety professionals withinsight to aid professional judgment when applying theTLVs.

The most current edition of the ACGIH Threshold LimitValues (TLVs®) for Chemical Substances and Physical Agents andBiological Exposure Indices (BEIs®) should be used. When refer-ring to an ACGIH TLV, the year of publication should alwayspreface the value, as in “the 2001 TLV for nitric oxide was 25ppm.” Note that the TLVs are not mandatory federal or stateemployee exposure standards, and the term TLV should not beused for standards published by OSHA or any agency except theACGIH.

Three categories of Threshold Limit Values are specifiedas follows:

TIME-WEIGHTED AVERAGE (TLV–TWA)This is the time-weighted average concentration for a con-ventional eight-hour workday and 40-hour workweek, towhich it is believed that nearly all workers may be repeatedlyexposed, day after day, without adverse effect.

SHORT-TERM EXPOSURE LIMIT (TLV–STEL)This is the concentration to which it is believed workers canbe exposed continuously for a short period of time withoutsuffering from: ➣ Irritation ➣ Chronic or irreversible tissue damage ➣ Narcosis of sufficient degree to increase the likelihood of

accidental injury, impair self-rescue, or materially reducework efficiency and provided that the daily TLV–TWA isnot exceeded

A STEL is a 15-min TWA exposure that should not beexceeded at any time during a workday, even if the eight-hourTWA is within the TLV-TWA. Exposures above the TLV-TWAup to the STEL should not be longer than 15 min and shouldnot occur more than four times per day. There should be atleast 60 min between successive exposures in this range.

The TLV–STEL is not a separate, independent exposurelimit; it supplements the TWA limit when there are recog-nized acute effects from a substance that has primarilychronic effects. The STELs are recommended only whentoxic effects in humans or animals have been reported fromhigh short-term exposures.

Note: None of the limits mentioned here, especially theTWA–STEL, should be used as engineering design criteria.

CEILING (TLV–C)This is the concentration that should not be exceeded duringany part of the working exposure. To assess a TLV–C ifinstantaneous monitoring is not feasible, the conventionalindustrial hygiene practice is to sample during a 15-minperiod, except for substances that can cause immediate irri-tation with short exposures.

For some substances (such as irritant gases), only one cat-egory, the TLV–C, may be relevant. For other substances,two or three categories may be relevant, depending on theirphysiological action. If any one of these three TLVs isexceeded, a potential hazard from that substance is presumedto exist.

Limits based on physical irritation should be consideredno less binding than those based on physical impairment.Increasing evidence shows that physical irritation can ini-tiate, promote, or accelerate physical impairment via inter-action with other chemical or biological agents.

The amount by which threshold limits can be exceededfor short periods without injury to health depends on manyfactors: the nature of the contaminant; whether very highconcentrations, even for a short period, produce acute poi-soning; whether the effects are cumulative; the frequencywith which high concentrations occur; and the duration ofsuch periods. All factors must be considered when decidingwhether a hazardous condition exists.

Skin Notation A number of the substances in the TLV list are followed bythe designation Skin. This refers to potential significantexposure through the cutaneous route, including mucousmembranes and the eyes, either by contact with vapors or,of probably greater significance, by direct skin contact withthe substance. Vehicles such as certain solvents can alter skinabsorption. This designation is intended to suggest appropriate measures for the prevention of cutaneousabsorption.

Mixtures Special consideration should be given in assessing the healthhazards that can be associated with exposure to mixtures oftwo or more substances.

Federal Occupational Safety and Health Standards The first compilation of the health and safety standardspromulgated by OSHA in 1970 was derived from thethen-existing federal standards and national consensusstandards. Thus, many of the 1968 TLVs established bythe ACGIH became federal standards or permissible exposure limits (PELs). Also, certain workplace qualitystandards known as ANSI maximal acceptable concentra-tions were incorporated as federal health standards in 29 CFR 1910.1000 (Table Z–2) as national consensus standards.


25

In adopting the ACGIH TLVs, OSHA also adopted theconcept of the TWA for a workday. In general:

TWA = CaTa+CbTb+…+CnT8

where Ta = the time of the first exposure period duringthe shift

Ca = the concentration of contaminant in period aTb = another time period during the shift Cb = the concentration during period bTn = the nth or final time period in the shift Cn = the concentration during period n

This simply provides a summation throughout the work-day of the product of the concentrations and the time peri-ods for the concentrations encountered in each time intervaland averaged over an 8-hour standard workday.

EVALUATION Evaluation can be defined as the decision-making processresulting in an opinion on the degree of health hazard posedby chemical, physical, biological, or ergonomic stresses inindustrial operations. The basic approach to controlling occu-pational disease consists of evaluating the potential hazard andcontrolling the specific hazard by suitable industrial hygienetechniques. (See Chapter 15, Evaluation, for more details.)

Evaluation involves judging the magnitude of the chemi-cal, physical, biological, or ergonomic stresses. Determiningwhether a health hazard exists is based on a combination ofobservation, interviews, and measurement of the levels ofenergy or air contaminants arising from the work process aswell as an evaluation of the effectiveness of control measuresin the workplace. The industrial hygienist then comparesenvironmental measurements with hygienic guides, TLVs,OSHA PELs, NIOSH RELs, or reports in the literature.

Evaluation, in the broad sense, also includes determiningthe levels of physical and chemical agents arising out of aprocess to study the related work procedures and to deter-mine the effectiveness of a given piece of equipment used tocontrol the hazards from that process.

Anticipating and recognizing industrial health hazardsinvolve knowledge and understanding of the several types ofworkplace environmental stresses and the effects of thesestresses on the health of the worker. Control involves thereduction of environmental stresses to values that the workercan tolerate without impairment of health or productivity.Measuring and quantitating environmental stress are the essen-tial ingredients for modern industrial hygiene, and are instru-mental in conserving the health and well-being of workers.

Basic Hazard-Recognition Procedures There is a basic, systematic procedure for recognizing andevaluating environmental health hazards, which includes thefollowing questions: ➣ What is produced?

➣ What raw material is used? ➣ What materials are added in the process? ➣ What equipment is involved? ➣ What is the cycle of operations? ➣ What operational procedures are used? ➣ Is there a written procedure for the safe handling and

storage of materials? ➣ What about dust control, cleanup after spills, and waste

disposal? ➣ Are the ventilating and exhaust systems adequate? ➣ Does the facility layout minimize exposure? ➣ Is the facility well-equipped with safety appliances such

as showers, masks, respirators, and emergency eyewashfountains?

➣ Are safe operating procedures outlined and enforced? ➣ Is a complete hazard communication program that meets

state or federal OSHA requirements in effect? Understand the industrial process well enough to see

where contaminants are released. For each process, performthe following: ➣ For each contaminant, find the OSHA PEL or other safe

exposure guideline based on the toxicological effect ofthe material.

➣ Determine the actual level of exposure to harmful phys-ical agents.

➣ Determine the number of employees exposed and lengthof exposure.

➣ Identify the chemicals and contaminants in the process. ➣ Determine the level of airborne contaminants using air-

sampling techniques. ➣ Calculate the resulting daily average and peak exposures

from the air-sampling results and employee exposure times. ➣ Compare the calculated exposures with OSHA stan-

dards, the TLV listing published by the ACGIH, theNIOSH RELs, the hygienic guides, or other toxicologi-cal recommendations.

All of the above are discussed in detail in the followingchapters.

Information Required Detailed information should be obtained regarding types ofhazardous materials used in a facility, the type of job opera-tion, how the workers are exposed, work patterns, levels ofair contamination, duration of exposure, control measuresused, and other pertinent information. The hazard potentialof the material is determined not only by its inherent toxic-ity, but also by the conditions of use (who uses what, where,and how long?).

To recognize hazardous environmental factors orstresses, a health and safety professional must first knowthe raw materials used and the nature of the products andby-products manufactured. Consult MSDSs for the sub-stances.

Any person responsible for maintaining a safe, healthful workenvironment should be thoroughly acquainted with the concen-


26

trations of harmful materials or energies that may be encounteredin the industrial environment for which they are responsible.

If a facility is going to handle a hazardous material, thehealth and safety professional must consider all the unex-pected events that can occur and determine what precautionsare required in case of an accident to prevent or controlatmospheric release of a toxic material.

After these considerations have been studied and propercountermeasures installed, operating and maintenance per-sonnel must be taught the proper operation of the health andsafety control measures. Only in this way can personnel bemade aware of the possible hazards and the need for certainbuilt-in safety features.

The operating and maintenance people should set up aroutine procedure (at frequent, stated intervals) for testing theemergency industrial hygiene and safety provisions that arenot used in normal, ordinary facility or process operations.

Degree of Hazard The degree of hazard from exposure to harmful environ-mental factors or stresses depends on the following: ➣ Nature of the material or energy involved ➣ Intensity of the exposure ➣ Duration of the exposure

The key elements to be considered when evaluating ahealth hazard are how much of the material in contact withbody cells is required to produce injury, the probability of thematerial being absorbed by the body to result in an injury, therate at which the airborne contaminant is generated, the totaltime of contact, and the control measures in use.

Air Sampling The importance of the sampling location, the proper time tosample, and the number of samples to be taken during thecourse of an investigation of the work environment cannotbe overstressed.

Although this procedure might appear to be a routine,mechanical job, actually it is an art requiring detailedknowledge of the sampling equipment and its shortcomings.The person taking the sample(s) needs to know where andwhen to sample; and how to weigh the many factors thatcan influence the sample results, such as ambient tempera-ture, season of the year, unusual problems in work opera-tions, and interference from other contaminants. Thesample must usually be taken in the breathing zone of anemployee (see Figure 1–5).

The air volume sampled must be sufficient to permit arepresentative determination of the contaminant to properlycompare the result with the TLV or PEL. The samplingperiod must usually be sufficient to give a direct measure ofthe average full-shift exposure of the employees concerned.The sample must be sealed and identified if it is to beshipped to a laboratory so that it is possible to identify posi-tively the time and place of sampling and the individual whotook the sample.

Area samples, taken by setting the sampling equipment ina fixed position in the work area, are useful as an index ofgeneral contamination. However, the actual exposure of theemployee at the point of generation of the contaminant canbe greater than is indicated by an area sample.

To meet the requirement of establishing the TWA con-centrations, the sampling method and time periods shouldbe chosen to average out fluctuations that commonly occurin a day’s work. If there are wide fluctuations in concentra-tion, the long-term samples should be supplemented by sam-ples designed to catch the peaks separately.

If the exposure being measured is from a continuous oper-ation, it is necessary to follow the particular operatorthrough two cycles of operation, or through the full shift ifoperations follow a random pattern during the day. For oper-ations of this sort, it is particularly important to find outwhat the workers do when the equipment is down for main-tenance or process change. Such periods are often also peri-ods of maximum exposure. (See Chapter 16, Air Sampling.)

As an example of the very small concentrations involved,the industrial hygienist commonly samples and measuressubstances in the air of the working environment in concen-trations ranging from 1 to 100 ppm. Some idea of the mag-nitude of these concentrations can be appreciated when onerealizes that 1 inch in 16 miles is 1 part per million; 1 centin $10,000, 1 ounce of salt in 62,500 pounds of sugar, and


27

Figure 1–5. Portable pump with intake positioned to collectcontinuous samples from the breathing zone of an employee.(Courtesy MSA)

1 ounce of oil in 7,812.5 gallons of water all represent 1 partper million.

OCCUPATIONAL SKIN DISEASES Some general observations on dermatitis are given in thischapter, but more detailed information is given in Chapter3, The Skin and Occupational Dermatoses. Occupationaldermatoses can be caused by organic substances, such asformaldehyde, solvents or inorganic materials, such as acidsand alkalis, and chromium and nickel compounds. Skin irri-tants are usually either liquids or dusts.

Types There are two general types of dermatitis: primary irritationand sensitization.

PRIMARY IRRITATION DERMATITISNearly all people suffer primary irritation dermatitis frommechanical agents such as friction, from physical agents suchas heat or cold, and from chemical agents such as acids, alka-lis, irritant gases, and vapors. Brief contact with a high con-centration of a primary irritant or prolonged exposure to alow concentration causes inflammation. Allergy is not a fac-tor in these conditions.

SENSITIZATION DERMATITISThis type results from an allergic reaction to a given substance.The sensitivity becomes established during the inductionperiod, which may be a few days to a few months. After thesensitivity is established, exposure to even a small amount ofthe sensitizing material is likely to produce a severe reaction.

Some substances can produce both primary irritation der-matitis and sensitization dermatitis. Among them areorganic solvents, chromic acid, and epoxy resin systems.

Causes Occupational dermatitis can be caused by chemical, mechan-ical, physical, and biological agents and plant poisons.

Chemical agents are the predominant causes of dermatitisin manufacturing industries. Cutting oils and similar sub-stances are significant because the oil dermatitis they cause isprobably of greater interest to industrial concerns than is anyother type of dermatitis.

Detergents and solvents remove the natural oils from theskin or react with the oils of the skin to increase sus-ceptibility to reactions from chemicals that ordinarily do notaffect the skin. Materials that remove the natural oils includealkalis, soap, and turpentine.

Dessicators, hygroscopic agents, and anhydrides take waterout of the skin and generate heat. Examples are sulfur diox-ide and trioxide, phosphorus pentoxide, strong acids such assulfuric acid, and strong alkalis such as potash.

Protein precipitants tend to coagulate the outer layers ofthe skin. They include all the heavy metallic salts and those

that form alkaline albuminates on combining with the skin,such as mercuric and ferric chloride. Alcohol, tannic acid,formaldehyde, picric acid, phenol, and intense ultravioletrays are other examples of protein-precipitating agents.

Oxidizers unite with hydrogen and liberate nascent oxy-gen on the skin. Such materials include nitrates, chlorine,iodine, bromine, hypochlorites, ferric chloride, hydrogenperoxide, chromic acid, permanganates, and ozone.

Solvents extract essential skin constituents. Examples areketones, aliphatic and aromatic hydrocarbons, halogenatedhydrocarbons, ethers, esters, and certain nitro compounds.

Allergic or anaphylactic proteins stimulate the productionof antibodies that cause skin reactions in sensitive people.The sources of these antigens are usually cereals, flour, andpollens, but can include feathers, scales, flesh, fur, and otheremanations.

Mechanical causes of skin irritation include friction, pres-sure, and trauma, which may facilitate infection with eitherbacteria or fungi.

Physical agents leading to occupational dermatitisinclude heat, cold, sunlight, x rays, ionizing radiation, andelectricity. The x rays and other ionizing radiation cancause dermatitis, severe burns, and even cancer. Prolongedexposure to sunlight produces skin changes and may causeskin cancer.

Biological agents causing dermatitis can be bacterial, fun-gal, or parasitic. Boils and folliculitis caused by staphy-lococci and streptococci, and general infection fromoccupational wounds, are probably the best known amongthe bacterial skin infections. These can be occupationallyinduced infections.

Fungi cause athlete’s foot and other types of dermatitisamong kitchen workers, bakers, and fruit handlers; fur, hide,and wool handlers or sorters; barbers; and horticulturists.Parasites cause grain itch and often occur among handlers ofgrains and straws, and particularly among farmers, laborers,miners, fruit handlers, and horticulturists.

Plant poisons causing dermatitis are produced by severalhundred species of plants. The best known are poison ivy,poison oak, and poison sumac. Dermatitis from these threesources can result from bodily contact with any part of theplant, exposure of any part of the body to smoke from theburning plant, or contact with clothing or other objects pre-viously exposed to the plant.

Physical Examinations Preplacement examinations help identify those especiallysusceptible to skin irritations. The examining physicianshould be given detailed information on the type of work forwhich the applicant is being considered. If the work involvesexposure to skin irritants, the physician should determinewhether the prospective employee has deficiencies or char-acteristics likely to predispose him or her to dermatitis (seeChapter 25, The Occupational Medicine Physician, formore details).


28

Preventive Measures Before new or different chemicals are introduced in an estab-lished process, possible dermatitis hazards should be carefullyconsidered. Once these hazards are anticipated, suitable engi-neering controls should be devised and built into theprocesses to avoid them.

The type, number, and amounts of skin irritants used invarious industrial processes affect the degree of control thatcan be readily obtained, but the primary objective in everycase should be to eliminate skin contact as completely as pos-sible. The preventive measures discussed in Chapter 18,Methods of Control, can be adapted to control industrialdermatitis.

CONTROL METHODS With employment in the United States shifting from manu-facturing to the service sector, many workplaces today pres-ent nontraditional occupational health hazards. Industrialhygienists need to possess the skills to implement controlmethodology in both industrial settings and in workplacessuch as laboratories, offices, health care facilities, and envi-ronmental remediation projects. Hazards can change withtime as well, so that hazard control systems require continualreview and updating.

Control methods for health hazards in the work envi-ronment are divided into three basic categories: 1. Engineering controls that engineer out the hazard, either

by initial design specifications or by applying methods ofsubstitution, isolation, enclosure, or ventilation. In thehierarchy of control methods, the use of engineering con-trols should be considered first.

2. Administrative controls that reduce employee exposuresby scheduling reduced work times in contaminant areas(or during cooler times of the day for heat stress exposure,for example). Also included here is employee training thatincludes hazard recognition and specific work practicesthat help reduce exposure. (This type of training isrequired by law for all employees exposed to hazardousmaterials in the course of their work.)

3. Personal protective equipment the employees wear to pro-tect them from their environment. Personal protectiveequipment includes anything from gloves to full bodysuits with self-contained breathing apparatus, and can beused in conjunction with engineering and administrativecontrols. Engineering controls should be used as the first line of

defense against workplace hazards wherever feasible. Suchbuilt-in protection, inherent in the design of a process, ispreferable to a method that depends on continual humanimplementation or intervention. The federal regulations,and their interpretation by the Occupational Safety andHealth Review commission, mandate the use of engineeringcontrols to the extent feasible; if they are not sufficient toachieve acceptable limits of exposure, the use of personal

protective equipment and other corrective measures may beconsidered.

Engineering controls include ventilation to minimize dis-persion of airborne contaminants, isolation of a hazardousoperation or substance by means of barriers or enclosures,and substitution of a material, equipment, or process to pro-vide hazard control. Although administrative control meas-ures can limit the duration of individual exposures, they arenot generally favored by employers because they are difficultto implement and maintain. For similar reasons, control ofhealth hazards by using respirators and protective clothing isusually considered secondary to the use of engineering con-trol methods. (See Chapter 18, Methods of Control.)

Engineering Controls Substituting or replacing a toxic material with a harmless oneis a very practical method of eliminating an industrial healthhazard. In many cases, a solvent with a lower order of toxic-ity or flammability can be substituted for a more hazardousone. In a solvent substitution, it is always advisable to exper-iment on a small scale before making the new solvent part ofthe operation or process.

A change in process often offers an ideal chance toimprove working conditions as well as quality and produc-tion. In some cases, a process can be modified to reduce thehazard. Brush painting or dipping instead of spray paintingminimizes the concentration of airborne contaminants fromtoxic pigments. Structural bolts in place of riveting, steam-cleaning instead of vapor degreasing of parts, and airlessspraying techniques and electrostatic devices to replace hand-spraying are examples of process change. In buying individ-ual machines, the need for accessory ventilation, noise andvibration suppression, and heat control should be consideredbefore the purchase.

Noisy operations can be isolated from the people nearbyby a physical barrier (such as an acoustic box to contain noisefrom a whining blower or a rip saw). Isolation is particularlyuseful for limited operations requiring relatively few workersor where control by any other method is not feasible.

Enclosing the process or equipment is a desirable methodof control because it can minimize escape of the contaminantinto the workroom atmosphere. Examples of this type ofcontrol are glove box enclosures and abrasive shot blastmachines for cleaning castings.

In the chemical industry, isolating hazardous processes inclosed systems is a widespread practice. The use of a closedsystem is one reason why the manufacture of toxic substancescan be less hazardous than their use.

Dust hazards often can be minimized or greatly reduced byspraying water at the source of dust dispersion. “Wettingdown” is one of the simplest methods for dust control. How-ever, its effectiveness depends on proper wetting of the dustand keeping it moist. To be effective, the addition of a wettingagent to the water and proper and timely disposal of the wet-ted dust before it dries out and is redispersed may be necessary.


29

Ventilation The major use of exhaust ventilation for contaminant con-trol is to prevent health hazards from airborne materials.OSHA has ventilation standards for abrasive blasting, grind-ing, polishing and buffing operations, spray finishing opera-tions, and open-surface tanks. For more details, see Chapter19, Local Exhaust Ventilation, and Chapter 20, DilutionVentilation of Industrial Workplaces.

A local exhaust system traps and removes the air con-taminant near the generating source, which usually makesthis method much more effective than general ventilation.Therefore, local exhaust ventilation should be used whenexposures to the contaminant cannot be controlled by sub-stitution, changing the process, isolation, or enclosure. Eventhough a process has been isolated, it still may require a localexhaust system.

General or dilution ventilation—removing and addingair to dilute the concentration of a contaminant to belowhazardous levels—uses natural or forced air movementthrough open doors, windows, roof ventilators, and chim-neys. General exhaust fans can be mounted in roofs, walls,or windows (see Chapters 19 and 20 for more details).

Consideration must be given to providing replacement air,especially during winter. Dilution ventilation is feasible only ifthe quantity of air contaminant is not excessive, and is partic-ularly effective if the contaminant is released at a substantialdistance from the worker’s breathing zone. General ventilationshould not be used where there is a major, localized source ofcontamination (especially highly toxic dusts and fumes). Alocal exhaust system is more effective in such cases.

Air conditioning does not substitute for air cleaning. Airconditioning is mainly concerned with control of air tem-perature and humidity and can be accomplished by systemsthat accomplish little or no air cleaning. An air-condition-ing system usually uses an air washer to accomplish temper-ature and humidity control, but these air washers are notdesigned as efficient air cleaners and should not be used assuch. (See Chapter 21, General Ventilation of Nonindus-trial Occupancies.)

Processes in which materials are crushed, ground, ortransported are potential sources of dust dispersion, andshould be controlled either by wet methods or enclosed andventilated by local exhaust ventilation. Points where convey-ors are loaded or discharged, transfer points along the con-veying system, and heads or boots of elevators should beenclosed as well as ventilated. (For more details, see Chapter19, Local Exhaust Ventilation.)

Personal Protective Equipment When it is not feasible to render the working environmentcompletely safe, it may be necessary to protect the workerfrom that environment by using personal protective equip-ment. This is considered a secondary control method toengineering and administrative controls and should be usedas a last resort.

Where it is not possible to enclose or isolate the processor equipment, ventilation or other control measures shouldbe provided. Where there are short exposures to hazardousconcentrations of contaminants and where unavoidablespills may occur, personal protective equipment must beprovided and used.

Personal protective devices have one serious drawback:They do nothing to reduce or eliminate the hazard. Theyinterpose a barrier between worker and hazard; if the barrierfails, immediate exposure is the result. The supervisor mustbe constantly alert to make sure that required protectiveequipment is worn by workers who need supplementaryprotection, as may be required by OSHA standards. (SeeChapter 22, Respiratory Protection.)

Administrative Controls When exposure cannot be reduced to permissible levelsthrough engineering controls, as in the case of air contami-nants or noise, an effort should be made to limit theemployee’s exposure through administrative controls.

Examples of some administrative controls are as follows: ➣ Arranging work schedules and the related duration of

exposures so that employees are minimally exposed tohealth hazards

➣ Transferring employees who have reached their upperpermissible limits of exposure to an environment whereno further additional exposure will be experienced

Where exposure levels exceed the PEL for one worker inone day, the job can be assigned to two, three, or as manyworkers as needed to keep each one’s duration of exposurewithin the PEL. In the case of noise, other possibilities mayinvolve intermittent use of noisy equipment.

Administrative controls must be designed only by knowl-edgeable health and safety professionals, and used cautiouslyand judiciously. They are not as satisfactory as engineeringcontrols and have been criticized by some as a means ofspreading exposures instead of reducing or eliminating theexposure.

Good housekeeping plays a key role in occupational healthprotection. Basically, it is a key tool for preventing dispersion ofdangerous contaminants and for maintaining safe and healthfulworking conditions. Immediate cleanup of any spills or toxicmaterial, by workers wearing proper protective equipment, is avery important control measure. Good housekeeping is alsoessential where solvents are stored, handled, and used. Leakingcontainers or spigots should be fixed immediately, and spillscleaned promptly. All solvent-soaked rags or absorbents shouldbe placed in airtight metal receptacles and removed daily.

It is impossible to have an effective occupational health pro-gram without good maintenance and housekeeping. Workersshould be informed about the need for these controls. Propertraining and education are vital elements for successful imple-mentation of any control effort, and are required by law as partof a complete federal or state OSHA hazard communicationprogram. (See Chapter 18, Methods of Control.)


30

SOURCES OF HELP Specialized help is available from a number of sources. Everysupplier of products or services is likely to have competentprofessional staff who can provide technical assistance orguidance. Many insurance companies that carry workers’compensation insurance provide industrial hygiene consulta-tion services, just as they provide periodic safety inspections.

Professional consultants and privately owned laboratoriesare available on a fee basis for concentrated studies of a specificproblem or for a facilitywide or companywide survey, whichcan be undertaken to identify and catalog individual environ-mental exposures. Lists of certified analytical laboratories andindustrial hygiene consultants are available from the AIHA.

Many states have excellent industrial hygiene departmentsthat can provide consultation on a specific problem. AppendixA, Additional Resources, contains names and addresses of stateand national health and hygiene agencies. NIOSH has a Tech-nical Information Center that can provide information onspecific problems. Scientific and technical societies that canhelp with problems are listed in Appendix A. Some provideconsultation services to nonmembers; they all have muchaccessible technical information. A list of organizations con-cerned with industrial hygiene is included in Appendix A.

SUMMARY No matter what health hazards are encountered, the approachof the industrial hygienist is essentially the same. Using meth-ods relevant to the problem, he or she secures qualitative andquantitative estimates of the extent of hazard. These data arethen compared with the recommended exposure guidelines. Ifa situation hazardous to life or health is shown, recommenda-tions for correction are made. The industrial hygienist’s rec-ommendations place particular emphasis on effectiveness ofcontrol, cost, and ease of maintenance of the control measures.

Anticipation, recognition, evaluation, and control are thefundamental concepts of providing all workers with ahealthy working environment.

BIBLIOGRAPHY American Conference of Governmental Industrial Hygienists.

Threshold Limit Values (TLVs®) for Chemical Substances andPhysical Agents and Biological Exposure Indices (BEIs®). Cin-cinnati: ACGIH, published annually.

American Conference of Governmental Industrial Hygienists.Air Sampling Instruments, 9th ed. Cincinnati: ACGIH,2001.

American Conference of Governmental Industrial Hygienistsand Committee on Industrial Ventilation. Industrial Venti-lation: A Manual of Recommended Practice, 24th ed. Lans-ing, MI: ACGIH, 2001.

American Conference of Governmental Industrial Hygienists.Documentation of Threshold Limit Values, 7th ed. Cincin-nati: ACGIH, 2001.

American Industrial Hygiene Association. Biosafety ReferenceManual, 2nd ed. Fairfax, VA: AIHA, 1995.

American Industrial Hygiene Association. Respiratory Protection:A Manual and Guideline, 3rd ed. Fairfax, VA: AIHA, 2001.

American Industrial Hygiene Association. Chemical ProtectiveClothing, Vol. 1. Fairfax, VA: AIHA, 1990.

American Industrial Hygiene Association. Chemical ProtectiveClothing, Vol. 2: Product and Performance Information. Fair-fax, VA: AIHA, 1990.

American Industrial Hygiene Association. The Noise Manual,5th ed. Fairfax, VA: AIHA, 2000.

American Industrial Hygiene Association. Engineering Ref-erence Manual, 2nd ed. Fairfax, VA: AIHA, 1999.

American Industrial Hygiene Association. Ergonomics GuideSeries. Fairfax, VA: AIHA, published periodically.

American Industrial Hygiene Association. Hygienic GuideSeries. Fairfax, VA: AIHA, published periodically.

American National Standards Institute, 1430 Broadway, NewYork, NY 10017.Respiratory Protection Standard Z88.2-1992.Fire Department Self-Contained Breathing Apparatus Program,ANSI/NFPA Standard 1404-1989.

Balge MZ, Krieger GR, eds. Occupational Health & Safety, 3rded. Itasca, IL: National Safety Council, 2000.

Burgess WA. Recognition of Health Hazards in Industry: A Reviewof Materials and Processes, 2nd ed. New York: Wiley, 1995.

Clayton GD, Clayton FE, Cralley LJ, et al., eds. Patty’s Indus-trial Hygiene and Toxicology, 4th ed. Vols. 1A–B, 2A–F,3A–B. New York: Wiley, 1991–1995.

Cralley LJ, Cralley LV, series eds. Industrial Hygiene Aspects ofPlant Operations: Vol. 1: Process Flows; Mutchler JF, ed. Vol.2: Unit Operations and Product Fabrication; Caplan KJ, ed.Vol. 3: Selection, Layout, and Building Design. New York:Macmillan, 1986.

Gosselin RE, et al. Clinical Toxicology of Commercial Products:Acute Poisoning, 5th ed. Baltimore: Williams & Wilkins, 1984.

Harber P, Schenker M, Balmes JR. Occupational & Environmen-tal Respiratory Diseases. St. Louis: Mosby/Yearbook, 1996.

Hathaway G, Procter NH, Hughes JP. Chemical Hazards of theWorkplace, 4th ed. Philadelphia: J.B. Lippincott, 1996.

Kroemer K, Grandjean E. Fitting the Task to the Human: ATextbook of Occupational Ergonomics, 5th ed. London, NewYork: Taylor & Francis, 1997.

Levy BS, Wegman DH. Occupational Health: Recognizing andPreventing Work-Related Disease, 4th ed. Boston: Little,Brown, 2000.

McDermott HJ. Handbook of Ventilation for ContaminantControl, 3rd ed. Stoneham, MA: Butterworth, 2000.

National Institute for Occupational Safety and Health, USDHHS Division of Safety Research. A Guide to Safety inConfined Spaces. Morgantown, WV: NIOSH Pub. no.87–113, 1987.

National Institute for Occupational Safety and Health, USDHHS Division of Safety Research. Criteria for a Recom-mended Standard, Occupational Exposure to Hot Environments,


31

revised criteria, NIOSH Pub. no. 86–113. Cincinnati:NIOSH Publications Dissemination, 1986.

National Institute for Occupational Safety and Health,USDHHS Division of Safety Research. ApplicationManual for the Revised NIOSH Lifting Equation. NIOSHPub. no. 94–110. Cincinnati: NIOSH Publications,1994.

National Institute for Occupational Safety and Health, USDHHS Division of Safety Research. Criteria for a Rec-ommended Standard: Working in Confined Spaces. NIOSHPub. no. 80–106. Cincinnati: NIOSH Publications Dis-semination, 1979.

National Safety Council. Accident Prevention Manual for Busi-ness & Industry, 12th ed. Vol. 1: Administration & Programs

(2001); Vol. 2: Engineering & Technology (2001); Vol. 3:Environmental Management, 2nd ed.(2000), Vol. 4: Secu-rity Management (1997). Itasca, IL: National Safety Coun-cil, 1997-2001.

National Safety Council. Protecting Workers’ Lives: A Safetyand Health Guide for Unions. Itasca, IL: National SafetyCouncil, 1992.

National Safety Council. Safety Through Design. Itasca, IL:NSC Press, 1999.

Rekus JF. Complete Confined Spaces Handbook. NationalSafety Council. Boca Raton, FL: Lewis Publishers, 1994.

Zenz C, Dickerson OB, Horvath EP, eds. Occupational Med-icine, 3rd ed. St. Louis, MO: Mosby-Year Book MedicalPublishers, 1994.


32

727

T his chapter discusses the background and definition of indus-trial hygiene, the interrelationship of the industrial hygien-

ist and other occupational groups, occupational settings in whichindustrial hygienists function, and training programs. The readerwill be able to define industrial hygiene, describe the types of jobsand settings in which industrial hygienists work, and identify spe-cific types of educational curricula, resources, and professionalorganizations that deal with industrial hygiene.

BACKGROUNDIndustrial hygienists are scientists, engineers, and publichealth professionals committed to protecting the health ofpeople in the workplace and the community. Industrialhygienists must be competent in a variety of scientificfields––principally chemistry, engineering, physics, toxicol-ogy and biology––as well as the fundamentals of occupa-tional medicine. Trained initially in one of these fields, mostindustrial hygienists have acquired by experience and post-graduate study a knowledge of the other allied disciplines.

In traditional industrial organizations, industrial hygien-ists were required to relate to personnel in other functionsincluding research and development, medical, management,safety, and production. Although the working relationshipswere close, it was understood that the industrial hygienistwas not expected to have expertise in these areas. In today’sdownsized organization, the industrial hygienist may also actas the safety or environmental professional. Flattened man-agement structures and the use of self-directed work teamshave created the need for flexible industrial hygienists whounderstand not only technical and scientific issues, but alsoproduction and research concerns. Hygienists at all levelsparticipate in management of cross-functional projects thatdraw on the expertise of all team members to develop andmaintain a safe and healthful work environment. One of the

The IndustrialHygienist

revised by Jill Niland, MPH, CIH, CSP

727 BACKGROUNDDefinition of Industrial Hygiene

728 JOB DESCRIPTIONSOccupational Safety and Health Technologist ➣ IndustrialHygienist ➣ Industrial Hygienist-in-Training (IHIT) ➣ IndustrialHygiene Manager ➣ Certified Industrial Hygienist (CIH)

732 INDUSTRIAL HYGIENE, CIVIL SERVICETraining Plan for Entry-Level OSHA Industrial Hygienists

734 PERSONNEL NEEDS AND PROBLEMSEducation and Training Programs ➣ Educational Resource Centers ➣ Professional Schooling ➣ Graduate Curricula ➣ Faculty ➣ Continuing Education

737 SUMMARY737 BIBLIOGRAPHY738 ADDENDUM: PROFESSIONAL SOCIETIES AND

COURSES OF INTEREST TO INDUSTRIAL HYGIENISTSAmerican Industrial Hygiene Association ➣ American Board ofIndustrial Hygiene ➣ American Academy of Industrial Hygiene ➣ American Conference of Governmental Industrial Hygienists➣ American Public Health Association

C h a p t e r

23

challenges for this generation of industrial hygienists ismaintaining a high level of technical expertise while broad-ening their roles in the activities just described.

Definition of Industrial HygieneThe American Industrial Hygiene Association (AIHA) hasdefined industrial hygiene as the anticipation, recognition,evaluation, and control of environmental factors arising inor from the workplace that may result in injury, illness, orimpairment, or affect the well-being of workers and mem-bers of the community. The AIHA describes industrialhygienists as

scientists and engineers committed to protecting thehealth and safety of people in the workplace and thecommunity. Industrial hygiene is considered a “sci-ence,” but it is also an art that involves judgment, cre-ativity and human interaction. The goal of theindustrial hygienist is to keep workers, their families,and the community healthy and safe. They play a vitalpart in ensuring that federal, state, and local laws andregulations are followed in the work environment.

Typical roles of the industrial hygienist include:➣ Investigating and examining the workplace for

hazards and potential dangers➣ Making recommendations on improving the safety

of workers and the surrounding community➣ Conducting scientific research to provide data on

possible harmful conditions in the workplace➣ Developing techniques to anticipate and control

potentially dangerous situations in the workplaceand the community

➣ Training and educating the community about job-related risks

➣ Advising government officials and participating inthe development of regulations to ensure the healthand safety of workers and their families

➣ Ensuring that workers are properly followinghealth and safety procedures

To develop the depth of knowledge necessary to excel inindustrial hygiene, many practitioners specialize in specificsub-disciplines, such as toxicology, epidemiology, chemistry,ergonomics, acoustics, ventilation engineering, and statis-tics, among others. Industrial hygienists often find theirwork overlapping with that of safety professionals, healthphysicists, engineers, and others in the fields of air pollution,water pollution, solid waste disposal, and disaster planning.

The industrial hygienist also makes contributions inemployee education and training, law and product liability,sales, labeling, and public information. Other health profes-sionals, including physicians, nurses, paramedics, and emer-gency medical technicians may at times assume someindustrial hygiene functions.

JOB DESCRIPTIONSThe job descriptions and titles of industrial hygiene person-nel may be somewhat similar to those of safety personnel. Inthe recent past they have evolved to reflect more team ori-ented or entrepreneurial approaches to safety and healthmanagement. However, many job descriptions have commonelements that loosely coalesce around the following themes.

The entry-level employee may be called a safety or healthtechnologist or technician. In this function the employeewill evaluate hazards and operations using a few simpleinstruments, and investigate minor incidents involvingoccupational health issues.

Occupational Safety and Health TechnologistIn 1976 the American Board of Industrial Hygiene (ABIH),in recognition of the growing group of technologistsengaged in industrial hygiene activities, established anindustrial hygiene technologist certification program. Thetechnologist was recognized as someone who had acquiredproficiency in an aspect or phase of industrial hygiene andwho performed his or her duties under the supervision of anindustrial hygienist. The designation certified industrialhygiene technologist was awarded after the applicant passedan examination. In 1985 the ABIH and the Board of Certi-fied Safety Professionals joined to operate this programthrough a joint committee, and the certification waschanged to Occupational Health and Safety Technologist(OHST). There are currently approximately 1,192 OHSTs.

Occupational Health and Safety Technologists performoccupational health and safety activities on a full-time orpart-time basis as part of their job duties. Such duties maybe ancillary to other job functions. Some examples of occu-pational health and safety activities are safety inspections;industrial hygiene monitoring; organizing and conductinghealth and safety training; investigating and maintainingrecords of occupational accidents, incidents, injuries, and ill-nesses; and similar functions. Candidates for the OHSTneed five years experience in occupational health or safetyactivities that comprise at least 35 percent of job duties,must pass the OHST examination, and complete Certifica-tion Maintenance requirements every five years. Candidatesmay substitute college courses in health and safety or anassociate degree or higher in certain disciplines for up to twoyears of the experience requirement. The OHST examina-tion deals with basic and applied science, laws, regulationsand standards, control concepts, investigation (post-event),survey and inspection techniques, data computation andrecord keeping, education, training, and instruction.

Industrial hygiene technicians and technologists canfunction efficiently in their limited technical area. They maytake samples and make measurements in the facility or com-munity. Their data and observations can be used to provideinformation for an industrial hygiene plan or program.

The duties of the technician require thoroughness,dependability, and a concern for the accuracy of the data

PART VI ➣ OCCUPATIONAL HEALTH AND SAFETY PROFESSIONS

728

being collected. They should be given a detailed outline ofthe duties, and have reference manuals readily available.Technicians must see the relevance and value of their efforts;these should be reflected in the technician’s salary and inworkplace structure. The industrial hygiene technician ispart of the team in which the technician and industrialhygienist share responsibility.

Technology changes and adds new problems to the oldones. Rarely are old hazards totally controlled. New prob-lems call for new approaches, new instrumentation, and newways of recording, compiling, and integrating data. Con-sider, for example, the advent of computerized exposuremonitoring databases accessible through intranets and theInternet, which allow much quicker sharing of data. Techni-cians must be willing to adjust to such changes, and may beable to become specialists in their own right. Some mayremain technicians, but many will move on to becomeindustrial hygienists.

Industrial HygienistThe employee at the next higher level, typically titled anindustrial hygienist, functions similarly to the safety engi-neer. The industrial hygienist carries out more detailed stud-ies of incidents; prepares recommendations and otherreports; reviews new processes, machinery, and layouts froma health (or safety) viewpoint; promotes occupational healthand safety education; and advises management about healthhazards, industrial hygiene practices, procedures, and equip-ment needs.

The industrial hygiene manager or supervisor has tradi-tionally had duties similar to those of a safety director, andmay manage the entire industrial hygiene program. In thelast decade many companies have collapsed the duties ofsafety and industrial hygiene manager into one function orposition, and have sometimes added responsibility for otherfunctions such as environmental safety, facility security, orrisk management. This has sometimes required that routineactivities such as exposure monitoring be delegated to per-sonnel at lower levels. Such facilities may also have concur-rently reduced the size of their safety/health/environmentaldepartments, and instead may rely on outside contractors toprovide the personnel and skills necessary for various indus-trial hygiene projects. Other facilities may put the burden ofmore technical exposure assessment back on the “manager,”who again becomes, in some cases, a “hands-on hygienist,”without the assistance of a staff to support him or her withnumerous responsibilities. Because they have the most expe-rience and expertise, managers in these situations are likely tobe called on to do the most complicated and advanced indus-trial hygiene tasks. Such a high degree of responsibility rein-forces the need for a recognized level of competence inindustrial hygiene personnel, which is provided by the certi-fication mechanism.

Many certified industrial hygienists are also certifiedsafety professionals and vice versa. Proficiency in industrial

hygiene, by examination and by experience, follows a routeroughly comparable to that of occupational safety. Moreover,the type of organization that employs the industrial hygien-ist or safety professional often requires similar skills of each.While many industrial hygienists work in private industry,many find positions in other types of endeavors that requireparticular skill sets.

Government industrial hygienists may find that a diplo-matic demeanor and well-developed interpersonal skills areamong their most important assets. Similarly consultantsmust have the flexibility to work with a wide range of clientsand demands. Universities require professional capabilitiesin research, teaching, and program administration. Univer-sity industrial hygienists need to be well versed in occupa-tional and environmental issues to deal with the manycomplex problems involving chemical safety, worker safety,student safety, buildings and ground worker safety, buildingworkers, and in those institutions affiliated with medicalschools, hospital health and safety. In such settings there aremany opportunities for hands-on industrial hygiene work.Campus health and safety staff, for example, may conductmany laboratory inspections that include field measure-ments such as hood flow rate and face velocity. They workwith contractors doing renovation projects and may need tomake air and ventilation measurements. Radiation safetystaff also do measurement surveys of areas where radiationsources are used.

Labor union industrial hygienists may handle technicalinquiries from contractors, union officials, and union mem-bers; develop curricula for training and regulatory analysesand testimony; perform job site visits, inspections, andaudits; and conduct presentations. Typically they do littleactual sampling. Writing and communication skills areessential, as are good interpersonal skills (used in listening toworkers and in conflict resolution).

Industrial Hygienist-in-Training (IHIT)This designation was formerly part of the ABIH’s certifica-tion program. It was issued after the candidate passed thecore examination, then the first of two exams taken tobecome a CIH. The last core exam was given by the ABIHin Fall, 2001. Now the procedure to become a CIH haschanged to one in which the candidate takes only one, com-prehensive examination. Those currently holding the IHITcertification (466 in number) have six years (from date ofissue) before their certificates expire. Before then they musttake the comprehensive exam and become CIHs. All of theother experience and education requirements to take theCIH exam still apply.

Historically, the ABIH had issued the IHIT categoryin 1972 because it then recognized that people withdegrees and only one year of work experience wanted totake the core examination before completing the fiveyears of experience in IH necessary to take the compre-hensive exam.

CHAPTER 23 ➣ THE INDUSTRIAL HYGIENIST

729

During the first years of his or her career, the IHITlearned about the elements of organization and manage-ment. He/she also learned to understand flowcharts andblueprints as part of developing skills in anticipating, recog-nizing, evaluating, and controlling occupational health haz-ards. IHITs find that increasing emphasis is placed oncommunication skills, and should have been encouraged todraft replies to letters, write reports, and prepare oral pre-sentations for editing by the supervisor.

If the IHIT has not already done so, he or she shouldbecome involved in the local section or chapter of the mostappropriate professional association. The IHIT should attendmeetings and work on committees, and should begin to meetother professionals outside the immediate workplace.

Industrial Hygiene FunctionsBecause they have more generalized skills, industrial hygien-ists should be able to make independent decisions. The indus-trial hygienist decides what information is available, whatadditional facts are needed, and how they will be used oracquired.

FUNCTIONSMore than 40 years ago, Radcliffe et al. (1959) described thesphere of responsibility of industrial hygienists, whichremains relevant today. They stated that the industrialhygienist will:➣ Direct the industrial hygiene program➣ Examine the work environment

Study work operations and processes and obtain fulldetails of the nature of the work, materials, and equipmentused, products and by-products, number and sex of employ-ees, and hours of work.

Make appropriate measurements to determine the magni-tude of exposure or nuisance to workers and the public,devise methods and select instruments suitable for suchmeasurements, personally (or through others under directsupervision) conduct such measurements, and study and testmaterial associated with the work operations.

Using chemical and physical means, study the results of testsof biological materials, such as blood and urine, when suchexamination will aid in determining the extent of exposure.➣ Interpret results of the examination of the environment

in terms of its ability to impair health, nature of healthimpairment, workers’ efficiency, and community nui-sance or damage, and present specific conclusions toappropriate parties such as management, health officials,and employee representatives

➣ Make specific decisions as to the need for or effectivenessof control measures and, when necessary, advise as to theprocedures that are suitable and effective for both thework environment and the general environment.

➣ Prepare rules, regulations, standards, and procedures forthe healthful conduct of work and the prevention of nui-sance in the community

➣ Present expert testimony before courts of law, hearingboards, workers’ compensation commissions, regulatoryagencies, and legally appointed investigative bodies

➣ Prepare appropriate text for labels and precautionaryinformation for materials and products to be used byworkers and the public

➣ Conduct programs for the education of workers and thepublic in the prevention of occupational disease andcommunity nuisance

➣ Conduct epidemiological studies of workers and indus-tries to discover the presence of occupational disease andestablish or improve Threshold Limit Values® or stan-dards for the maintenance of health and efficiency

➣ Conduct research to advance knowledge concerning theeffects of occupation on health and means of preventingoccupational health impairment, community air pollu-tion, noise, nuisance, and related problems

The industrial hygienist should be able to determinewhether there are alternative solutions to a problem. Obvi-ously, leadership and management skills are required.

Few problems are so unique that peer acceptance is notrequired. Thus, the industrial hygienist must be able to workwith other industrial hygienists in the same functional area,whether in industry, government, labor unions, insurance,consulting, or teaching.

The industrial hygienist should also have the experience,knowledge, and capability to specify corrective procedures tominimize or control environmental health hazards.

Many organizations try to “grow their own industrialhygienist”––that is, taking someone from inside the organiza-tion, with some scientific background and a knowledge of thefirm’s products, and exposing him or her to a crash programin industrial hygiene. An organization initiating an industrialhygiene effort must recognize that knowledge of the organiza-tion alone is not enough for the optimal solution of industrialhygiene problems. The industrial hygienist must have the nec-essary professional education and expertise.

The capable industrial hygienist who has made the in-house adjustment to the organization’s problems should havethe versatility and capability to deal with any industrialhygiene problem that may arise. In the development of anew product, for example, he or she should be able to meetwith research and development personnel and find out whatinformation is needed. This might include toxicologicalinformation, labeling requirements, assistance to customers,and any special engineering control requirements as theresearch effort progresses through pilot state to commercialproduction.

With the assistance of a qualified epidemiologist, theindustrial hygienist can study an existing (or even a sus-pected) environmental health problem through epidemiolog-ical and biostatistical approaches, in addition to the usualsampling and measuring procedures. The industrial hygienistshould know where to go (for example, personnel, purchas-ing, or process engineering) for the information he or she


730

needs to investigate and solve a problem. If the industrialhygienist knows of another organization engaged in makingsimilar products, he or she can exchange information with itsindustrial hygienist and may be able to exchange visits.

Industrial hygienists must work well with other profes-sionals, such as physicians, nurses, safety engineers, toxicolo-gists, health physicists, and others, in and out of theorganization. They must also communicate and work veryclosely with employees. Employees have insights into poten-tial health hazards in their work area that only those workingwith the processes every day can possess. They are a primarysource of information and suggestions for the industrialhygienist.

Industrial Hygiene ManagerIn an industry setting, the industrial hygiene manager super-vises the technical and support staff in a health and safetydepartment; prepares budgets and plans; is familiar with gov-ernment agencies related to the operation; relates industrialhygiene operations to research and development, produc-tion, environmental, and other departments or functions;and prepares appropriate reports. He or she may be called onto assist the corporate legal department when regulatory andworker compensation issues arise. The industrial hygienemanager should be certified by the ABIH (see the descrip-tion of this organization in the Addendum to this chapter).

Many aspects of industrial hygiene expertise are unique. Itmakes sense for the industrial hygienist to extend his or hercapabilities and sphere of activity by delegating responsibili-ties to others. This calls for supervisory and planning skills.The industrial hygienist must be able not only to plan,direct, and supervise technicians and assistants, but also toplan, program, and budget the activities of the departmentand staff. As a manager, he or she must establish prioritiesand initiate appropriate corrective action. The industrialhygienist and the industrial hygiene manager must both beeffective communicators. Many aspects of their work involveformal or impromptu training of employees, managers, andvisitors to a facility. These professionals may also be called onto discuss an organization’s health and safety goals andaccomplishments with the media and other members of thepublic, and they must be articulate, knowledgeable, and ableto convey technical information in nontechnical language.

In the last decade many companies have collapsed theduties of safety and industrial hygiene manager into onefunction or position, and have sometimes added responsibil-ity for other functions such as environmental safety, facilitysecurity or risk management. This has sometimes requiredthat routine activities such as exposure monitoring be dele-gated to personnel at lower levels. Such facilities may alsohave concurrently reduced the size of their safety/health/environmental departments, and instead may rely onoutside contractors to provide the personnel and skills neces-sary for various industrial hygiene projects. Other facilitiesmay put the burden of more technical exposure assessment

back on the “manager,” who again becomes, in some cases, a“hands-on hygienist,” without the assistance of a staff tosupport him or her with numerous responsibilities. Becausethey have the most experience and expertise, managers inthese situations are likely to be called on to do the most com-plicated and advanced industrial hygiene tasks. Such a highdegree of responsibility reinforces the need for a recognizedlevel of competence in industrial hygiene personnel, which isprovided by the certification mechanism.

Certified Industrial Hygienist (CIH)The designation of certified industrial hygienist by the ABIHindicates that a person has received special education and haslengthy experience and proven professional ability in thecomprehensive practice or the chemical practice of industrialhygiene.

The employer, employees, and the public have a right tobe reasonably assured that the person to whom their lives areentrusted is professionally capable. One route by which suchprotection is provided is through licensing, usually by a gov-ernment agency, a peer review arrangement or both. Certifi-cation by the American Board of Industrial Hygiene (ABIH)provides this assurance. Additionally, industrial hygienists ina number of states have worked to develop various forms oflicensing to ensure that only well qualified industrial hygien-ists are allowed to promote themselves as such.

For certification by the ABIH, an individual must meet rig-orous standards of education and experience before proving,by written examination, competency in either the comprehen-sive practice of industrial hygiene or the chemical practice (seeAddendum). Diplomates of the ABIH are eligible for mem-bership in the American Academy of Industrial Hygiene.

Certification provides some assurance that this individualpossesses a high level of professional competence. The certi-fied industrial hygienist is the person most likely to direct anindustrial hygiene program capably, to work with other pro-fessions and government agencies, and to provide the visionand leadership of an industrial hygiene program to keepoccupational hazards at a minimum in a rapidly changingtechnology and society. At the time of this writing, there areabout 6400 active CIHs.

All CIHs must actively work to maintain their certifica-tion by earning a specified number of certification mainte-nance points during a five-year cycle. These points areawarded for working as an industrial hygienist; participatingin professional associations; attending approved meetings,seminars and short courses; participating on technical com-mittees; publishing in peer-reviewed journals; teaching,when not part of their primary practice; and other ABIH-approved activities.

The American Board of Industrial Hygiene has intro-duced a new industrial hygiene certification in 2001 forthose professionals who have industrial hygiene responsibili-ties, but do not qualify for the Certified Industrial Hygienist(CIH) designation. This will include environmental health


731

science (EHS) professionals who do not practice industrialhygiene a majority of their total work time as well as thosewho primarily function in a single industrial hygiene areasuch as air pollution, ergonomics, or health physics, andwho do not meet the CIH requirement for broad-scope IHwork experience. This certification will be titled the Certi-fied Associate Industrial Hygienist (CAIH).

The basic qualifications will include:➣ a bachelor’s degree with at least 30 semester hours of sci-

ence and math➣ industrial hygiene college or professional development

courses covering fundamentals, measurements, controlsand toxicology

➣ four years of post-bachelor, professional-level industrialhygiene experience (at least 25% IH activities)

➣ successful completion of a written exam The certification will be designed to demonstrate compe-

tence in applying fundamental industrial hygiene knowledgeand skills. (Consult ABIH for the most current rules.)

Of course, all of the previously described categories ofABIH certification––CIH, CAIH, IHIT, and OHST––areopen to all industrial hygiene personnel, whether they areemployed in industry, government, labor unions, educa-tional institutions, or consulting, as long as they meet thequalifications. However, federally employed industrialhygienists also have their own unique training programs thatreflect the structure and duties of their positions.

INDUSTRIAL HYGIENE, CIVIL SERVICEFor industrial hygiene trainees, assignments are selected anddesigned to orient the new employee into the field of indus-trial hygiene, to determine areas of interest and potential, torelieve experienced industrial hygienists of detailed and sim-ple work, and to develop the trainee’s knowledge and com-petence. Specific assignments are carried out under directsupervision of a qualified industrial hygienist, includingrecognition and evaluation of hazards, identification of con-trols, calibration of equipment, collection of samples, andinitial preparation of reports. During inspections, the traineeobserves specific safety items.

Under the general supervision of a senior industrialhygienist, the trainee begins to conduct more complexindustrial hygiene inspections, including selection of sam-pling methods and locations, evaluation of controls andmonitoring procedures, and preparation of reports. Com-pleted work is reviewed for overall adequacy and confor-mance with policy and precedents. The industrial hygienistdetermines engineering feasibility, sets periods of abatement,interprets standards, and defends appeals under supervisionof a senior industrial hygienist.

The senior industrial hygienist performs complete industrialhygiene inspections and prepares the final report. He or shedetermines engineering feasibility, sets periods of abatement,defends appeals, interprets standards, and provides offsite con-

sultation. He or she receives general assignment of objectivesand definition of policy from supervisors. The senior industrialhygienist differs from the industrial hygienist in that he or shereceives more complex assignments and may act in place of theindustrial hygiene supervisor when the supervisor is absent.

Training Plan for Entry-Level OSHA Industrial HygienistsOn July 7, 1992, Assistant Secretary for Occupational Safety andHealth Dorothy Y. Strunk issued an OSHA instruction specify-ing a revised training program for OSHA compliance personnel.The instruction provided policies and guidelines for the imple-mentation of technical training programs and described a federalprogram change that also affects state OSHA programs. Thisrevised training program applies to both newly hired and expe-rienced compliance personnel and is still in effect.

The training program is designed to provide a series oftraining courses supported by on-the-job training and self-instructional activities to ensure that compliance personnelare able to apply technical information and skills to theirwork; however, the elements of the training program are notmeant to be prerequisites for advancement.

Objectives. On completion of the developmental trainingprogram, the compliance safety and health officer (CSHO)will have the following skills:➣ A working knowledge of the fundamentals of hazard

recognition, evaluation, and control➣ Adequate knowledge of the implementation of engineer-

ing controls, abatement strategies, and the interpretationof data

➣ A reasonable comprehension of basic industrial processesand the ability to make quantitative observations andmeasurements

➣ Field experience in the proper calibration and use ofmeasuring instruments

➣ The ability to perform solo or team inspections in mosttypes of industries

➣ Knowledge of regulations and laws that involve safetyand health in the workplace

➣ The ability to present inspection data in a legal proceed-ing efficiently

➣ The ability to make a referral to other appropriate indus-trial hygienists or safety officers

ORGANIZATIONAL TRAINING RESPONSIBILITIESThe mission of the Occupational Safety and Health Admin-istration (OSHA) Office of Training and Education is toprovide a program to educate and train employers andemployees in the recognition, avoidance, and prevention ofunsafe and unhealthful working conditions and to improvethe skill and knowledge levels of personnel engaged in workrelating to the Occupational Safety and Health Act of 1970.

The Office of Training and Education consists of fourcomponents:


732

➣ Division of Training and Educational Programs. This divi-sion is responsible for planning agency technical trainingprograms and for managing the Susan B. Harwoodgrants.

➣ Division of Training and Educational Development. Thisdivision is responsible for developing and updating safetyand health training programs and related materials.

➣ Division of Administration and Training Information. Thisdivision is responsible for providing administrative andinformational programs for the Office of Training andEducation.

➣ OSHA Training Institute. The Training Institute isresponsible for the delivery of training to the populationsserved by the agency.

Specific responsibilities of the OSHA Training Instituteinclude the following:➣ Conducting programs of instruction for federal and state

compliance officers, state consultants, other federalagency personnel and private sector employers, employ-ees, and their representatives

➣ Participating in the development of course outlines,detailed lesson plans, and other educational aids neces-sary to carry out training programs

Each of OSHA’s ten regions has a regional training officeror technician, who assists the regional administrator in coor-dinating the management of all regionwide training pro-grams. This individual serves as the focal point in theregional office, ensuring the successful implementation ofthe training program for regional compliance personnel.Specifically, the regional training officer or technician assistsin providing resource material and current training informa-tion to area directors and supervisors concerning the imple-mentation of the objectives of the training program andevaluates and monitors all records of training.

In OSHA area offices, the area director has overall respon-sibility for ensuring and implementing the development andtraining of newly hired and experienced CSHOs under his orher supervision. The supervisor, however, serves as the mainfocal point in the area office for ensuring training. Thesupervisor provides and coordinates instruction, assistance,and guidance to the CSHOs in order to meet the trainingprogram objectives. Reviewing and maintaining progressrecords for each CSHO and assigning senior CSHOs toassist in on-the-job training of new hires is also performed bythe supervisor.

The program itself provides a well-articulated progressionof training requirements for newly hired personnel. The ele-ments include formal training at the OSHA Training Insti-tute and informal training such as self-study and on-the-jobtraining (OJT). Figure 23–1 illustrates the developmentaltraining plan for new hires.

INFORMATIONAL PROGRAMThe developmental training plan begins with the study of aninformational package of materials developed jointly by the

national office, the regional office, and the Office of Train-ing and Education. Contents include information on theU.S. Department of Labor; an introduction, history, andpurpose statement; the structures of regional and area offices,procedures, and libraries; common OSHA acronyms; indi-vidual training development programs; and such handoutitems as organizational charts, the Field Operations Manual(FOM), standards, directives, personal protective equip-ment, and instruments.

SELF-STUDY PROGRAMBefore attending the initial compliance course at the OSHATraining Institute, each CSHO is required to complete threeself-study programs on the OSHAct, Chapter III of theField Inspection Reference Manual (FIRM), and IntegratedManagement Information Systems (IMIS) forms 1, 1A, 1B,and 1B-IH. During these self-study assignments, the CSHObecomes familiar with the basic OSHAct requirements;studies basic inspection procedures in Chapter III of theFOM, and becomes familiar with the most commonly usedforms.

OSHA TRAINING INSTITUTEAfter completing the basic self-study prerequisites, eachCSHO is required to complete coursework in one of threetracks: safety, health, or construction.

Initial compliance course. This provides new CSHOs withan understanding of occupational safety and health programs,and a working knowledge of the FOM and OSHA policies.

Technical courses in safety, health, or construction. Thesecourses provide new-hire CSHOs with a thorough introductionto the organization and content of the standards and to hazardrecognition and documentation.

Inspection techniques and legal aspects.This provides newCSHOs with an understanding of basic communication skills,formal requirements and processes of the legal system, andinvestigative techniques related to OSHA compliance activity.

Additional technical courses (at least two courses re-quired). These provide the CSHO with technical knowl-edge, skills, and information on hazard recognition as relatedto OSHA requirements. The specific courses are determinedby the supervisor based on individual need. Figure 23–1 liststhe technical courses in each track.

Crossover training. Because CSHOs must be familiar withgeneral concepts of safety and health, each CSHO is requiredto complete crossover training during the developmentalperiod. CSHOs on the safety or construction track areencouraged to attend the introduction to health course;industrial hygienists are encouraged to attend the introduc-tion to safety course.


733

CONTINUING MAINTENANCE OF SKILLS AND KNOWLEDGEOnce the training period is completed, CSHOs typically requireadditional training to keep themselves current in the safety andhealth field. At a minimum, each CSHO is required to attend atechnical course once every 3 years at the OSHA Training Insti-tute. If an institute course has changed significantly during theyears, the CSHO is permitted to repeat the course.

CSHOs are also encouraged to pursue other trainingopportunities available both within the Department ofLabor and elsewhere.

PERSONNEL NEEDS AND PROBLEMSThe American Industrial Hygiene Association reports anational membership of 12,300 in late 2001, with 76 local

sections.. If local section AIHA members who are not alsonational members are included, the figure rises to approxi-mately 15,000.

The American Conference of Governmental IndustrialHygienists (ACGIH) has a membership of approximately 5,000industrial hygienists from 52 countries. Many hygienists belongto both organizations, limiting the data’s usefulness as an esti-mate of the total number of professional industrial hygienists.

In 1975, OSHA, using 1973 NIOSH data, reported anational census of only 500 industrial hygienists, but 15,000occupational safety and health specialists. The OSHA estimateindicated a then-current need for 5,500 industrial hygienistsand 24,000 safety and health specialists. At that time, OSHAalso predicted the need for 11,900 industrial hygienists and62,300 occupational safety and health specialists by 1985.


734

Figure 23–1. The OSHA training tracks for compliance personnel. (Source: OSHA Instruction TED 1.12A, Office of Training andEducation.)

Training tracks for compliance personnel

#100 Initial Compliance Course*

Industial hygiene track Construction trackSafety track

#125 Introduction to industrialhygiene standards for industrial hygienists*

#200 Constructionstandards

#105 Introductionto safety officers

#141 Inspectiontechniques andlegal aspects*



Technical coursesSelect 2 from below



Hazardous MaterialsElectrical

Machine guardingFire protection

Cranes for general IndustryMaritime

State plan monitoringBasic accident investigation

Note: * To be completed during the first year of the developmental period.

NoiseVentilationRespiratorsToxicology

ErgonomicsMaritime

State plan monitoringBasic accident investigation

Cranes in constructionExcavationTunneling

ScaffoldingFall protection

MaritimeState plan monitoring

Basic accident investigation

#101 Safety hazardrecognition for

industrial hygienistsor


#121 Introduction toindustrial hygiene

for safety personnelor

#105 Introductionto safety officers

#121 Introduction toindustrial hygiene

for safety personnelor


Cycles of growth and contraction in industry and govern-ment will undoubtedly continue to affect the demand forindustrial hygienists well into the 21st century. In the 1980s,expansion of the need for hygienists came in nontraditionalareas such as environmental remediation, indoor air quality,and a number of areas that many see as temporary trends;asbestos management and remediation projects are primeexamples. In the 1990s, however, downsizing by many cor-porations resulted in industrial hygienists often functioningas safety and environmental or even risk-management pro-fessionals, or delegating responsibilities such as safety train-ing to less trained and credentialed personnel. Someindustrial hygienists whose corporate jobs were eliminatednow serve as private consultants to a variety of clients,including the corporations they left. Whereas 42 percent ofAIHA’s members are in private industry, consultants (infirms or self-employed) make up about 24–25 percent of themembership, up from about 10 percent in 1984.

Additionally, if a contraction of government agenciesoccurs because of a changing political climate, this may mutethe demand for industrial hygienists in both industry andgovernment. However, the 1990s also saw a movement bylarge industry, particularly multinational or “global” employ-ers, to adopt national and international voluntary standards,such as those developed through the American NationalStandards Institute (ANSI) and the International Organiza-tion for Standardization (ISO). ISO 14000, which deals withan organization’s management of its relationship to the envi-ronment, is such an example. Industrial hygienists clearlyhave roles to play in developing and helping implement thegoals and objectives of these programs to ensure that anorganization truly enhances worker safety as it conforms tothese voluntary standards.

The absolute need for individuals trained in the preven-tion of disease and preservation of health and safety will notchange. Eventually, data such as worker compensation costsand illness and injury rates will reveal the need for preven-tion rather than repair of injury.

Education and Training ProgramsThe education and training programs for industrial hygieneinclude professional school training, graduate curricula, andcontinuing education (short courses). Professional schoolcurricula in industrial hygiene generally culminate in a Mas-ter of Science or a Master of Public Health degree.

Educational Resource CentersNIOSH’s findings of shortages of trained occupationalsafety and health graduates were cited in successful effortsto expand training grants programs. One part of thisexpansion was the introduction of multidisciplinary educa-tional resource centers (ERCs). The other part was growthof single-discipline training grants.

Congress authorized creation of up to 20 EducationalResource Centers for occupational safety and health in 1976.

Funding increased from $2.9 million in 1977 to $12.9 mil-lion in 1980, and in 2000 the ERCs now number 15. In1998 the name of these facilities was changed to Educationand Research Centers. These centers provide continuingeducation to occupational health and safety professionals;combine medical, industrial hygiene, safety, and nursingtraining so that graduates are better able to work effectivelyin complex and diverse conditions; conduct research; andconduct regional consultation services. All ERCs are locatedin universities. The centers are distributed as widely as possi-ble to give regional representation and to meet training needsfor all areas of the nation.

The ERCs should not be confused with the OSHA Train-ing Institute education centers, a program in which desig-nated nonprofit organizations offer the most frequentlyrequested OSHA Training Institute courses for the privatesector and other Federal agency personnel. There are cur-rently 12 of these OSHA education centers around the U.S.

Professional SchoolingA program of study leading to a professional degree in indus-trial hygiene should start with two years of basic arts and sci-ences, two years of derivative sciences and advanced subjects,and two years of professional courses. Such an advanceddegree might appropriately be designated Doctor of Occu-pational Health, Doctor of Public Health, Doctor of Science,or Doctor of Engineering. Regardless of its name, however, itshould be clearly understood that such a degree is a profes-sional scholar’s degree.

Graduate CurriculaGraduate study programs have generally been developed toprovide in-depth knowledge of a particular subject area andto develop scholarly research capabilities. The AccreditingBoard of Engineering and Technology (ABET) has accred-ited master’s level programs in industrial hygiene since 1985and currently also accredits baccalaureate level programs. Inearly 2000 there are 21 accredited master’s level programsand 5 accredited baccalaureate level programs. ABET con-siders industrial hygiene (as well as safety, industrial manage-ment, or quality management) to be engineering relatedfields. The American Academy of Industrial Hygiene hasbeen the lead organization responsible for submitting pro-gram criteria for industrial hygiene baccalaureate and mas-ter’s programs to ABET. In the past these criteria statedspecific numbers and types of semester hours of credit thatdegree candidates needed to complete the degree program.For example, a baccalaureate degree program required 63 ormore semester hours of college-level mathematics, includingtechnological courses and a minimum of 21 semester hoursin communications, humanities, and social sciences. In thelate 1990s ABET’s approach changed to one that askedorganizations to state their criteria in terms of outcomemeasures. While these are still undergoing final review, theproposed new criteria for baccalaureate and master’s level


735

programs in industrial hygiene are a combination of generalcriteria expected in all types of engineering related programs,and specific criteria for industrial hygiene programs.

The general criteria for baccalaureate level programsrequire the institution to evaluate and monitor students todetermine if the program is meeting its objectives and thatstudents are meeting program requirements.

Such programs must have detailed published educationalobjectives and curriculum and processes that ensure theachievement of these objectives as well as a system of ongo-ing evaluation that demonstrates achievement of theseobjectives and uses the results to improve the effectiveness ofthe program.

Programs must be able to demonstrate that graduateshave:(a) an ability to apply knowledge of mathematics, science,

and engineering-related applied sciences(b) an ability to design and conduct experiments, as well as

to analyze and interpret data(c) an ability to formulate or design a system, process or pro-

gram to meet desired needs(d) an ability to function on multi-disciplinary teams(e) an ability to identify and solve engineering-related

problems(f ) an understanding of professional and ethical responsibility(g) an ability to communicate effectively(h) the broad education necessary to understand the impact

of solutions in a global and societal context(i) a recognition of the need for, and an ability to engage in

life-long learning(j) a knowledge of contemporary issues(k) an ability to use the techniques, skills, and modern sci-

entific and technical tools necessary for professionalpractice.

Each program must have an assessment process with doc-umented results. Evidence must be given that the results areapplied to the further development and improvement of theprogram. The assessment process must demonstrate that theoutcomes important to the mission of the institution andthe objectives of the program, including those listed above,are being measured.

The professional component requirements specify subjectareas appropriate to engineering-related programs, but donot prescribe specific courses. The program’s faculty mustassure that the engineering-related curriculum devotes ade-quate attention and time to each component, consistentwith the objectives of the program and institution. Studentsmust be prepared for engineering-related practice throughthe curriculum culminating in comprehensive projects orexperiences based on the cumulative knowledge and skillsacquired in earlier coursework.

FacultyRather than specifying specific numbers of faculty as it didin the past ABET now will require that

the faculty must be of sufficient number as determinedby student enrollment and the expected outcome compe-tencies of the program. The faculty must have sufficientqualifications and must ensure the proper guidance of theprogram and its evaluation and development. The over-all competence of the faculty may be judged by such fac-tors as education, diversity of backgrounds, applicableexperience, teaching performance, ability to communi-cate, enthusiasm for developing more effective programs,level of scholarship, participation in professional societies,and applicable certifications, registrations, or licensures.

The proposed criteria also state requirements for facilities,institutional support and financial resources. Criteria spe-cific to industrial hygiene programs require that they

must demonstrate that graduates have necessaryknowledge, skills, and attitudes to competently andethically implement and practice applicable scientific,technical, and regulatory aspects of Industrial Hygiene.Graduates must be prepared to anticipate, recognize,evaluate and control exposures of workers and others tophysical, chemical, biological, ergonomic and psychoso-cial factors, agents and/or stressors that can potentiallycause related diseases and/or dysfunctions.

ABET also specifies a list of required outcome measuressuch as being able to describe qualitative and quantitativeaspects of generation of agents, factors, and stressors. TheABET criteria state that

Master’s level program candidates must hold an earnedbaccalaureate that prepares them to apply the basicprinciples of college-level mathematics, inorganic andorganic chemistry, physics, and biology.

Criteria for master’s-level programs require the follow-ing additions beyond the baccalaureate level: (i) minimumof one year of study beyond the basic-level, consisting ofcourses with increased depth and rigor; (ii) an applied sci-ence project or research activity resulting in a report thatdemonstrates both mastery of the subject matter and a highlevel of professional and public communication skills; (iii)an adequate foundation in statistics, applied sciences,and/or related professional practice; and, (iv) advancedqualitative and quantitative problem-solving skills.

Continuing EducationA wide variety of opportunities exist for industrial hygienistswho want to remain technically current, receive training inpreviously unfamiliar aspects of industrial hygiene, pursueacademic coursework leading to a more advanced degree, orearn certification maintenance points in order to maintainCIH certification.


736

A number of universities offer coursework leading todegrees. Also available at such universities are usually shortcourses (a few days or weeks long) on specific industrialhygiene topics. Summer institutes (1–4 weeks long) concen-trating on a particular area of industrial hygiene are anothercontinuing education opportunity.

NIOSH publishes an annual catalogue of all such trainingcourses nationwide at universities that are funded as NIOSHERCs. Most ERCs contain an industrial hygiene componentthat includes coursework leading to academic degrees andshort courses. The catalogue can be obtained through theNIOSH publications dissemination office or at its website.Between 1993 and 1998 NIOSH provided continuing edu-cation for 184,000 professionals. A number of other not-for-profit and for-profit training organizations provide shortcourses in industrial hygiene and related topics. These includethe National Safety Council and professional industrialhygiene and safety societies as well as consulting firms. Thecomputerization of nearly all U.S. workplaces has engenderedthe development of a wide range of self-paced educationalactivities, including programs that can be delivered by CD-ROM or over the Internet. Large numbers of web sites nowaddress safety, industrial hygiene, and environmental issues.There are also a variety of list-servers on environmental andoccupational health that deliver up-to-date information to acomputer subscription list. There are on-line discussiongroups and bulletin boards; for example the ACGIH sponsors“topic walls” that allow users to participate in posting ques-tions and answers on industrial hygiene topics, broken intothe categories of Recognition, Evaluation, and Control. Newtechnologies also allow courses and seminars to be deliveredover the web or via video conference.

SUMMARYThe need to control exposures to a rapidly rising number ofchemicals and hazardous agents and to comply with andenforce governmental regulations and voluntary guidelineshas brought about greater demand for industrial hygienists.This demand exists in private industry, labor unions, gov-ernment, and academic organizations.

Individuals practicing industrial hygiene routinely workas a team; thus, the physician, the nurse, the safety profes-sional, and the industrial hygienist are quite accustomed toworking together. Other professions are included as needed;these include toxicologists, health physicists, epidemiolo-gists, statisticians, professional trainers, and educators. Ateam approach, using the knowledge and skills of all theseprofessionals, increases the effectiveness of programs to pre-vent occupational disease and injuries and helps to anticipatefuture requirements.

The need continues for industrial hygienists to interpretthe findings of environmental investigations and to designand implement control measures. The industrial hygienistmust, therefore, have the generalist’s grasp of varied disci-

plines in order to interact with divergent groups in develop-ing and maintaining the most effective program.

Educational requirements for industrial hygienists willcontinue to expand with the increasing need to monitor andcontrol hazardous agents and to comply with more stringentgovernment regulations and voluntary guidelines and stan-dards such as those promulgated by the American NationalStandards Institute and ACGIH. The training program forOSHA CSHOs was also discussed.

Personnel from three professional specialties––industrialhygiene, safety, and environmental health––will be workingeven more closely together in the future, their responsibilitiesoverlapping in many instances. The separation between theseprofessions has become increasingly blurred, and meldingmay eventually lead to the creation of a single professionwhose scope is made up of what is currently recognized todayas industrial hygiene and safety.

BIBLIOGRAPHYAmerican Board of Engineering and Technology, 2000-2001

Related Engineering Courses. ABET website. 2000. Avail-able at: www.abet.org/rac/2000.htm. Accessed May 11,2000 and earlier dates.

The American Board of Industrial Hygiene (ABIH)/Boardof Certified Safety Professionals (BCSP) joint committeefor the certification of occupational health and safetytechnologists. Council on Certification of Health, Envi-ronmental and Safety Technologists website (CCHEST).2001. Available at www.cchest.org. Accessed Nov 13,2001 and earlier dates.

About APHA. American Public Health Association Website.2000. Available at: www.apha.org/about/. Accessed May15, 2000 and earlier dates.

Academy of Industrial Hygiene. American IndustrialHygiene Association website. 2000. Available at:www.aiha.org/aih/aihindex.html. Accessed May 11, 2000and earlier dates.

All About AIHA. American Industrial Hygiene Association web-site. 2001. Available at: http://www.aiha.org/index2a.html.Accessed Nov 13, 2001 and previous dates.

Berry CM. What is an industrial hygienist? National SafetyNews 107:69–75, 1973.

Constantin MJ, et al. Status of industrial hygiene graduateeducation in U.S. institutions. AIHA Journal55:537–545, 1994.

Corn M, Heath ED. OSHA response to occupational healthpersonnel needs and resources. AIHA Journal 38:11–17,1977.

Hermann ER. Education and training of industrial hygien-ists. National Safety Congress Trans 12:64–66, 1975.

Information about Certification for the Practice of IndustrialHygiene. American Board of Industrial Hygiene website.2000. Available at: www.abih.org. Accessed May 11, 2000and earlier dates. Office of Technology Assessment, U.S.


737

Congress. Preventing Injury and Illness in the Workplace(unpublished manuscript). New York: InfoSource, 1985.

Profile of Members. ACGIH website. 2000. Available at:http://www.acgih.org/members/profile.htm. AccessedMay 11, 2000 and earlier dates.

Radcliffe JC, Clayton GD, Frederick WG, et al. Industrialhygiene definition, scope, function, and organization.AIHAJ 20:429–430, 1959.

ADDENDUM: PROFESSIONAL SOCIETIESAND COURSES OF INTEREST TO INDUSTRIAL HYGIENISTS

American Industrial Hygiene AssociationThe AIHA is a nonprofit professional society for people prac-ticing industrial hygiene in industry, government, labor, aca-demic institutions, and independent organizations. In late2001, AIHA had a membership of 12,300 members, plus 76local sections drawn from the United States, Canada, and 43other countries.

The AIHA was established in 1939 by a group of indus-trial hygienists to provide an association devoted exclusivelyto industrial hygiene. AIHA is a national society of profes-sionals engaged in protecting the health and well-being ofworkers and the general public through the scientific appli-cation of knowledge concerning chemical, engineering,physical, biological, or medical principles to minimize envi-ronmental stress and to prevent occupational disease.

The AIHA promotes the recognition, evaluation, andcontrol of environmental stresses arising in the workplaceand encourages increased knowledge of occupational andenvironmental health by bringing together specialists in thisfield. The American Industrial Hygiene Conference andExposition, cosponsored by AIHA, draws more than 10,000industrial hygiene professionals each May or June.

AIHA MEMBERSHIP QUALIFICATIONS AND TYPESFull membership is for individuals who have worked prima-rily in industrial hygiene-related activities for at least threeyears and meet other educational requirements. Full mem-bers may serve on committees, vote, and be elected to theAIHA Board of Directors.

Diplomate members are those individuals who meet therequirements for board certification in their respective disci-pline as recognized by AIHA. AIHA members in goodstanding who meet these criteria will belong to the respectivediplomate division of AIHA. They will have the same orga-nizational rights as full members.

Associate membership is for individuals who have lessthan three years of experience in the industrial hygiene field.An associate member may serve on committees and vote, butmay not be elected to the AIHA Board of Directors.

Any person who interacts with occupational and environ-mental health professionals may become an affiliate member

of AIHA. An affiliate member may serve on committees, butmay not vote or be elected to the AIHA Board of Directors.

A full-time college student may become a student mem-ber of AIHA. A student member may not serve on commit-tees, vote, or hold office. Student members can receive theAIHA Journal at a special discounted price.

Organizational membership is open to organizations hav-ing an interest in the industrial hygiene profession.

LOCAL SECTION MEMBERSHIPAny person with a professional interest in industrial hygienemay apply for membership in an AIHA local section. Appli-cation for membership in a local section should be made tothe local section.

Address: American Industrial Hygiene Association, 2700Prosperity Ave., Suite 250, Fairfax, VA 22031, (703) 847-8888, www.aiha.org.

American Board of Industrial HygieneThe American Board of Industrial Hygiene (ABIH) was estab-lished to improve the practice and educational standards ofthe profession of industrial hygiene. To this end, the ABIHengages in the following activities:➣ To receive and process applications for examinations and

to evaluate the education and experience qualificationsof the applicants for such examinations

➣ To grant and to issue (to qualified people who pass theboard’s examinations) certificates acknowledging theircompetence in industrial hygiene and to revoke certifi-cates so granted or issued for cause

➣ To provide for maintenance of certification by requiringevidence of continued professional qualifications by cer-tificate holders in the comprehensive or chemical prac-tice of industrial hygiene

➣ To maintain a record of certificate holders➣ To furnish to the public, and to interested people or

organizations, a roster of certificate holders having spe-cial training, knowledge, and competence in industrialhygiene

The American Board of Industrial Hygiene issues three cat-egories of certificates. The first certifies that the individual hasthe required education, experience, and professional ability inthe comprehensive practice or chemical practice of industrialhygiene (CIH). The second category is the industrial hygienistin training (IHIT) certification. This designation has beeneliminated. Current IHITs have six years to test for CIH status.The third category, the occupational health and safety technol-ogist (OHST) designation, is a joint certification with theBoard of Certified Safety Professionals (BCSP). The OHSTexamination procedure is administered by the CCHEST (seeBibliography).

As previously discussed, ABIH introduced a new certifi-cation, the Certified Associate Industrial Hygienist, in2001. Each applicant for the traditional Certification inindustrial hygiene until recently has had to pass a two-part


738

examination. In 2001 the first, or Core, examination waseliminated. But the more visible change (beginning springof 2001) was the elimination of the Core Exam (and IHITprogram). The ABIH decided that two full-day examina-tions were not necessary to identify CIH level practitioners.A single exam has been constructed to test both the generalknowledge/information aspect previously tested by the CoreExam and the more applied/experiential aspects of theComprehensive Exam.

Also, the existing specialty certification in Chemical Prac-tice and the Indoor Environmental Quality (IEQ) subspecialtycertification program were both suspended in 2000.

CERTIFICATION MAINTENANCEThe ABIH also administers a certification maintenance pro-gram for CIHs. The purpose of this program is to ensure thatCIHs continue to develop and enhance their professionalindustrial hygiene skills for the duration of their careers. Thecertificate is granted for a period of six years, after whichtime it expires unless renewed. Certificate holders must pro-vide evidence to the board of their continued professionalqualifications in order to renew the certificate. Activities thatare accepted as evidence include continuing professionalindustrial hygiene practice; membership in an approved pro-fessional society (other than the American Academy ofIndustrial Hygiene); attendance at approved meetings, semi-nars, and short courses; participation in technical commit-tees; publishing in peer-reviewed journals; teaching that isnot part of the diplomate’s primary practice; approvedextracurricular professional activities; and reexamination orexamination for an additional certification. Points for theapproved activities are awarded and publicized by the board,as is a schedule for renewal of certificates.

Besides being entitled to use the CIH designation, peoplecertified in either comprehensive practice or chemical prac-tice become members of the American Academy of IndustrialHygiene and their names are published in the annual rosterof the academy. The names of IHITs are also published in theacademy roster.

Address: American Board of Industrial Hygiene, 6015West St. Joseph, Suite 102, Lansing, Michigan 48917-3980,(517) 321-2638, www.abih.org.

American Academy of Industrial HygieneThe American Academy of Industrial Hygiene (AAIH) hasbeen a professional association of practicing industrialhygienists who have participated successfully in the certifica-tion program administered by the American Board of Indus-trial Hygiene (ABIH). Completion of this programdemonstrates the highest degree of proficiency in the practiceof industrial hygiene.

In 1957, the American Industrial Hygiene Association(AIHA) set out to establish a certification program for qual-ified industrial hygienists. The American Conference ofGovernmental Industrial Hygienists joined the effort in

1958. The ABIH was incorporated as an independent organ-ization to develop and administer the certification program.Six members from each sponsoring organization made up thefirst board; its first annual meeting was held in 1960. In1966, the diplomates activated the AAIH as a professionalorganization. In 1999 AIHA and AAIH voted to merge theAcademy into AIHA; the AAIH became the Academy ofIndustrial Hygiene.

The purpose of the AIH is to establish high standards ofprofessional conduct and professionalism among those prac-ticing in the field of industrial hygiene. AIH seeks to pro-mote recognition of the need for high-quality industrialhygiene practice to ensure healthful work conditions in theoccupations and industries its members serve.

Activities include establishment of a code of ethics toserve as a guide for professional conduct by industrialhygienists; promotion of the recognition of industrialhygiene as a profession by individuals, employers, and regu-latory agencies; advancement of board certification as a basicqualification for employment as an industrial hygienist inboth public and private organizations; accreditation of aca-demic programs in industrial hygiene in cooperation withthe Accreditation Board of Engineering and Technology; andrecruitment of students into academic programs and trainingthrough initial education and continuing education for prac-ticing industrial hygienists.

The AIH sponsors the Professional Conference on Indus-trial Hygiene to provide a forum for exploring professionalissues. Continuing education opportunities also are pro-vided. The conference is aimed primarily at issues encoun-tered by the more experienced industrial hygienist but is notrestricted to members of AIH.

American Conference of GovernmentalIndustrial HygienistsThe American Conference of Governmental IndustrialHygienists (ACGIH) was organized in 1938 by a group ofgovernment industrial hygienists who desired a medium forthe free exchange of ideas and experiences and the promo-tion of standards and techniques in occupational and envi-ronmental hygiene.

As an organization devoted to the development of admin-istrative and technical aspects of worker health protection, theACGIH has contributed substantially to the development andimprovement of official occupational health services to indus-try and labor. ACGIH endeavors to provide opportunities,information, and other resources needed by those who protectworker health and safety. Technical committees, publications,symposia, journals, and other programs work toward this goal.The committees on industrial ventilation and Threshold LimitValues® are recognized throughout the world for their expert-ise and contributions to industrial hygiene. The ACGIH setsTLVs® and annually updates these values.

The mission of the ACGIH is to be an indispensableresource for industrial hygienists and related professionals


739

worldwide. Its purposes are to promote excellence in environ-mental and occupational health; to provide technical informa-tion of the highest quality; to benefit the occupational healthand well-being of people worldwide; and to serve the mem-bership and continually improve the organization, includingits financial and human resources. It operates a PublicationsClearinghouse and Resource Information Center and providesa variety of products and services members’ needs, includingthe yearly revision of Threshold Limit Values® for Chemical Sub-stances and Physical Agents and Biological Exposure Indices.®

This booklet is an indispensable resource that contains quanti-tative exposure guidelines industrial hygienists use to compareto air and biological sampling results.

ACGIH MEMBERSHIPACGIH was originally formed as an organization of indus-trial hygienists who worked in government. It has recentlyexpanded its scope to offer membership to a broader spec-trum of practitioners. Today, anyone who is engaged in thepractice of industrial hygiene or occupational and environ-mental health and safety is eligible for one of six categoriesof membership. Consult ACGIH for the most current rules.

A full member is an industrial hygienist or occupationalhealth, environmental health, or safety professional whosefull-time, primary employment is with a governmental agencyor an educational institution and who is engaged in health orsafety services, standard setting, enforcement, research, oreducation. Full members are accorded full voting privilegesand can serve as officers or members-at-large of the Board ofDirectors as well as on any appointive committee.

An associate member is a person professionally employedin a full-time activity closely allied to industrial hygiene,occupational health, environmental health, or safety who iseither an employee of a government agency or an educa-tional institution, or who works more than 50 percent of hisor her time on a government contract at a government facil-ity. An associate member may also be a person with at least10 years of membership in the full or technical category whohas retired or is eligible for retirement benefits from a gov-ernment agency or educational institution but who isemployed in the field at least 25 percent of his or her timeby a government agency or educational institution. Associatemembers may vote on all conference matters and may serveas a member-at-large on the Board of Directors or as a mem-ber of an appointive committee.

A technical member is a technician employed in a full-timeactivity by a government agency or an educational institu-tion in industrial hygiene, occupational health, environmen-tal health, or safety. A technical member may also be aperson who works more than 50 percent of his or her timeon a government contract at a government facility that isengaged in such services. Technical members have the samevoting and service privileges as associate members.

Student members are people officially enrolled in a full-time course of study directly related to industrial hygiene,

occupational health, environmental health, or safety. Evi-dence of academic enrollment must include one of the fol-lowing: current transcript, current class schedule, or a letterof reference from an academic advisor (on university or col-lege letterhead) indicating that the applicant is a full-timestudent. Students may not vote or hold elected office butmay serve on appointive committees.

An emeritus member is a full, associate, or technical mem-ber who has retired from the practice of industrial hygiene,occupational health, environmental health, or safety and whohas been a member of the conference for a minimum of 10consecutive years. Retirement is defined as employment lessthan 25 percent of full-time. These members retain the rightsand privileges of the category from which they qualified forthis status.

Affiliate members are people engaged in health or safetyservices who are not currently eligible for another categoryof membership. They may not vote on conference matters orhold elected office but they may serve as consultants onappointive committees.

Address: ACGIH, Kemper Meadow Center, 1330 Kem-per Meadow Drive, Cincinnati, OH 45240.

American Public Health AssociationThe American Public Health Association (APHA), estab-lished in 1872, is 50,000 strong in its collective member-ship, which represents all the disciplines and specialties inthe public health spectrum. The APHA is devoted to theprotection and promotion of public health. It achieves thisgoal in several ways:➣ Sets standards for alleviating health problems➣ Initiates projects designed for improving health, both

nationally and internationally➣ Researches health problems and offers possible solutions

based on that research➣ Launches public awareness campaigns about special

health dangers➣ Publishes materials reflecting the latest findings and

developments in public healthThe APHA has 35 special sections, including an occupa-

tional health and safety section that includes occupationalhealth physicians and nurses, industrial hygienists, and otherallied occupational health professionals. Each APHA sectionhas its own professional meetings to provide a forum for theexchange of ideas.

APHA MEMBERSHIPSix types of membership are available:➣ Regular membership is available to all health professionals.➣ Contributing membership provides additional associa-

tion benefits.Special memberships include the following:

➣ Student/trainee: people enrolled full-time in a college oruniversity or occupied in a formal training program inpreparation for entry into a health career


740


741

➣ Retired: APHA members who have retired from active public health practice and no longer derive signif-icant income from professional health-related activities

➣ Consumer: people who do not derive income fromhealth-related activities

➣ Special health workers: people employed in communityhealth whose annual salary is less than $30,000 (or itsequivalent for foreign nationals)

Address: American Public Health Association, 800 IStreet NW, Washington, DC, 20001-3710, (202) 777-APHA, Website: www.apha.org

Documents

Fundamentals of Industrial Hygine