Safety (Industrial Engineering)

7/28/2019 Safety (Industrial Engineering)

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Chapter 20

Industrial Hygiene: Toxic

Substances and Confined Spaces


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Major Topics

Hazards in the workplace

OSH Act and industrial hygiene

Airborne contaminants Asbestos hazards

Sick building syndrome

NIOSH and industrial hygiene OSHA confined spaces standard


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Industrial Hygiene

Industrial hygiene is a safety and health

profession that is concerned with

predicting, recognizing, assessing,

controlling, and preventing environmental

stressors in the workplace that can cause

sickness or serious discomfort to workers.

Common stressors include gases, fumes,vapors, dusts, mists, noise, and radiation.


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Responsibilities of the modern

industrial hygienist Code of ethics of the American Academy of Industrial

Hygiene:

To ensure the health of employees

To maintain an objective approach in recognizing,

assessing, controlling and preventing health hazardsregardless of outside pressure and influence.

To help employees understand the precautions that theyshould take to avoid health problems.

To respect employees honesty in matters relating toindustrial hygiene

To make the health of employees a higher priority thanobligations to the employer


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Role of the safety and health

professional

In companies that employ specialists, theirrecommendations are used by safety and healthprofessionals to develop, implement, monitor,and evaluate the overall safety and healthprogram.

If specialists are not employed, safety and healthprofessionals are responsible for seeking theadvice and assistance necessary to predict,recognize, assess, control, and overcomeenvironmental stressors that may causesickness or serious discomfort to employees.


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OSHA requirements relating to

industrial hygiene Use of warning labels and other means to make employees aware of

potential hazards, symptoms of exposure, precautions, andemergency treatment

Prescription of appropriate personal protective equipment and othertechnological preventive measures [29CFR 1910.133 and 1910.134subpart I]

Provision of medical tests to determine the effect on employees ofexposure to environmental stressors

Maintenance of accurate records of employee exposures toenvironmental stressors that are required to be measured ormonitored

Accessibility of monitoring tests and measurement activities toemployees

Availability of monitoring tests and measurement activity records toemployees on request

Notification of employees who have been exposed to environmentalstressors at a level beyond the recommended threshold and correctiveaction being taken


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Typical categories of hazard in the

workplace Categories: chemical, physical, biological and

ergonomic.

Chemical hazards: include mists, vapors, gases, dusts,and fumes.

Physical hazards: include noise, vibration, extremes oftemperature, and excessive radiation.

Biological hazards: come from molds, fungi, bacteria,and insects. Bacteria may be introduced in theworkplace through sewage, food waste, water or insectdroppings.

Ergonomic hazards: poorly designed workstations andtools, conditions that put workers in awkward positions orimpair their visibility.


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Routes of entry for toxic agents

The most common routes of entry for toxic

agents are inhalation, absorption,

injection, and ingestion.


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Airborne contaminants: dust,

fumes, smoke, mists, and gases Dusts are various types of solid particles that are produced when a given type

of organic or inorganic material is scrapped, sawed, ground, drilled, handled,heated, crushed or otherwise deformed. The degree of the hazard depends onthe toxicity of the parent material and the size and level of concentration of theparticles.

Fumes: Welding, heat treating, and metalizing all involve the interaction ofintense heat with the parent material, which results in tiny particles of the

parent material which can be inhaled. Smoke: Smoke is the result of incomplete combustion of carbon material. Tiny

soot or carbon particles remain that can be inhaled.

Aerosols: are liquid or solid particles that are so small that they can remainsuspended in air long enough to be transported over a distance. They can beinhaled.

Mists: are tiny liquid droplets suspended in the air. Mists are formed whenvapors return to a liquid state through condensation and when the application

of a sudden force or pressure turns a liquid into particles. Gases: become hazardous when they fill a confined unventilated space. The

mist common forms of gases in industrial settings are from welding and theexhaust from internal combustion engines.


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Remove or contain asbestos

Following factors should be considered:

Is there evidence that the ACM (asbestos containingmaterial) is deteriorating? What is the potential for furtherdeterioration?

Is there evidence of physical damage to the ACM? Whatis the potential for future damage?

Is there evidence of water damage to the ACM orspoilage? What is the potential for future damage orspoilage?

The most widely used methods for dealing with asbestosare removal, enclosure and encapsulation.


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ANSI Z9.8 (indoor air

quality/HVAC) General Coverage: ANSI Z9.8 is very specifically written to apply

primarily to office space. It applies specifically to employeeoccupancies in non industrial spaces including general officespaces, commercial operations, and office spaces with industrialfacilities.

Application flexibility: When the provisions of ANSI Z9.8 conflict with

other standards the more stringent standard is to take precedence. Acceptable air quality: Employers may establish ceiling limits (e.g. if

more than 2% of the employees complain about air quality problemsthe ceiling limit has been reached).

Tobacco smoke: The standard requires that employers evaluatesmoking in the workplace and apply whatever management controls

are appropriate.


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Asbestos: removal, enclosure and

encapsulation Removal: known as asbestos abatement. The area in question must

be completely enclosed in walls of tough plastic. The enclosed areamust be ventilated by High efficiency particle absolute (HEPA)filtered negative air machines. The ACM (asbestos containingmaterial) must be covered with a special liquid solution to cut downon the release of asbestos fibers. The ACM must be placed in leak

proof containers for disposal. Enclosure: use HEPA filtered negative air machines in conjunction

with drills or any other tools that may penetrate or otherwise disturbACMs. Construct the enclosing walls of impact resistant air tightmaterial. Post signs indicating the presence of ACMs within theenclosed area. Note the enclosed area on the plans of the building.

Encapsulation: of asbestos involves spraying the ACMs with aspecial sealant that binds them together thereby preventing therelease of fibers. The sealant should harden into a tough impactresistant skin. This approach is generally used on acoustical plasterand similar materials.


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Medical examinations for

employees who handle ACMs Medical examinations conducted at least annually should

be required for employees who handle ACMs. Theseexaminations should include front and back chest X-raysthat are at least 7 by 14. The examination should also

test pulmonary function, including forced vital capacityand forced expiratory volume at one second.

Medical records on such employees should be kept forat least 20 years. They should contain the completemedical history of the employee. These records must be

made available on request to employees, pastemployees, health care professionals, employeerepresentatives, and OSHA personnel.


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Exposure thresholds: time weighted average, short

term exposure limit, and exposure ceiling

Threshold Limit Value-Time weighted average (TLV-TWA): The timeweighted average for a conventional 8 hour work day and 40 hourwork week for a given substance to which it is believed that nearlyall workers may be repeatedly exposed on a daily basis withoutsuffering ill effects. For example the TLV-TWA for liquefiedpetroleum gas is 1000 parts per million (ppm).

Threshold Limit Value-Short term exposure limit (TLV-STEL): ASTEL is defined as a 15 minute TWA exposure that should not beexceeded at any time during the work day period. It should notoccur more than 4 times in the day (with at least 60 minutesbetween exposures). For example the TVL-STEL for isopropyl etheris 310 ppm.

Threshold Limit Value-Ceiling (TLV-C): The concentration of a givensubstance that should not be exceeded at any point during anexposure period.


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Evaluating hazards in the

workplace For hazard evaluation the following

considerations are important:

The nature of the material or substanceinvolved, the intensity of the exposure, and the

duration of the exposure. Key factors to consider are how much exposure

is required to produce injury or illness; thelikelihood that enough exposure to produce

injury or illness will take place; the rate ofgeneration of airborne contaminants; the totalduration of the exposure; and the prevention andcontrol measures used.


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Generic prevention and control

strategies

Most prevention and control strategies can

be placed in one of the following 4

categories:

Engineering controls

Ventilation

Personal protective equipment Administrative controls


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Prevention/control strategy: engineering controls,

ventilation, personal protective equipment

Engineering Controls: replacing toxic material with one that is lesshazardous or redesigning a process to make it less stressful or toreduce exposure to hazardous material or conditions, isolatinghazardous process to reduce the number of people exposed to itand introducing moisture to reduce dust.

Ventilation: exhaust ventilation involves trapping and removing

contaminated air. Used with such processes as abrasive blasting,grinding, polishing, buffing, and spray painting or finishing. Dilutionventilation involves simultaneously removing and adding air to dilutea contaminant to acceptable levels.

Personal protection: Personal protective equipment (PPE) imposesa barrier between the worker and the hazard. Typical equipment

include safety goggles, face shields, gloves, boots, earmuffs, earplugs, full body clothing, and respirators.

Specially designed eyewash and emergency wash stations (fig 20-8,9, 10) should be readily available and accessible in any work settingwhere contaminants may be present.


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Worker self protection strategies

Know the hazards in your workplace: take time to identify allhazardous material and conditions in your workplace and know thesafe exposure levels of each.

Know the possible effects of hazards in your workplace: Typicaleffects of workplace hazards include respiratory damage, skindisease and irritation, injury to the reproductive system, and damage

to the blood, lungs, central nervous system, eyesight and hearing. Use PPE properly: Choosing the right equipment, getting a proper

fit, correctly cleaning and storing equipment, and inspectingequipment regularly for wear and damage.

Understand and obey safety rules: Read warning labels beforeusing any contained substance, handle materials properly, read and

obey signs, and do only authorized work. Practice good personal hygiene: Wash thoroughly after exposure to

a hazardous substance, shower after work, wash before eating, andseparate potentially contaminated work clothes from others beforewashing them.


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NIOSH and Industrial Hygiene

The National Institute of Safety and Health [NIOSH] ispart of the Department of Health and Human Services[HHS].

The main focus of the agency is on toxicity levels and

human tolerance levels of hazardous substances. NIOSH prepares recommendations for OSHA standards

dealing with hazardous substances and NIOSH studiesare made available to employers.

Their continually updated list of toxic materials andrecommended tolerance levels are extremely helpful toindustrial hygienists concerned with keeping theworkplace safe.


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Toxic Substance

A toxic substance is one that has a

negative effect on the health of a person

or animal.


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Effect of a toxic substance

Toxic effects are functions of several

different factors including the following:

Properties of the substance

Amount of the dose

Level of exposure

Route of entry Resistance of the individual to the

substance


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Common routes of entry of toxic

substances

The most common routes of entry of toxic

substances are inhalation, absorption,

injection and ingestion.


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Dose-response relationship

A dose of toxic substance can be expressed in anumber of different ways depending on thecharacteristic of the substance: amount per unitof body weight, amount per body surface area,

or amount per unit of volume of air breathed. Olishifski expressed the dose response

relationship mathematically as : C * T = K

where:

C = concentration T = duration (time) of exposure

K = constant


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Dose threshold, lethal dose, and

lethal concentration

Dose threshold: is the minimum dose required to

produce a measurable effect.

Lethal dose: is the dose that is highly likely to

cause death. Lethal concentration: of an inhaled substance is

the concentration that is highly likely to result in

death. With inhaled substances the duration of

exposure is critical because the amount inhaled

increases with every unprotected breath.


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Acute and chronic effects and

exposures

Acute effects and exposures involves a suddendose of a highly concentrated substance. Theyare usually the result of an accident that result inan immediate health problem ranging fromirritation to death.

Chronic effects and exposures involve limitedcontinual exposure over time. Consequently theassociated health problem develops slowly.

Fig 20-3 page 439: selected toxic substancesand the organs they affect most.


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Classification of airborne toxics

Airborne toxic substances are classified according to thetype of effect they have on the body.

The primary classifications are:

irritants - cause irritation to skin, eyes, nose, mouth,

throat, and upper respiratory tract. asphyxiants - disrupt breathing so severely that

suffocation results.

narcotics/anesthetics - can inhibit normal operation of

central nervous system. With all airborne contaminants concentration and

duration of exposure are critical concerns.


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Carcinogen

A carcinogen is any substance that can

cause a malignant tumor or a tissue that

may become cancerous.


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OSHA chemical process standard,

EPA clean air act, and SARA OSHA chemical process standard: The standard requires chemical

producers to analyze their processes to identify potentially hazardoussituations and to assess the extent of the hazard. Having done so theymust accommodate this knowledge in their emergency response plansand take action to minimize the hazards. Specific additionalrequirements include: compiling process safety information,maintaining safe operating procedures, training and educating

employees, maintaining equipment, conducting incidentinvestigations, developing emergency response plans, andconducting safety compliance audits.

EPA clean air act (1990): The law is designed to reduce air pollution in the form of hazardous air pollutants, acid rain, and smog by 56billion pounds per year. This includes a 75% reduction in air toxics, a50% cut in acid rain, and a 40% decrease in smog.

Superfund Amendments and Reauthorization Act (SARA): This law isdesigned to allow individuals to obtain information about hazardouschemicals in their communities so that they can protect themselves incase of emergency. It applies to all companies that use, make,transport, or store chemicals.


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Threshold limit value (TLV)

Threshold limit values: refer to airborne

concentrations of substances and represent

conditions under which it is believed that nearly

all workers may be repeatedly exposed day afterday without adverse effect.

Threshold limits are based on the best available

information from industrial experience, from

experimental human and animal studies, andwhen possible a combination of the three.


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Time weighted average and ceiling

The time weighted average for aconventional 8 hour work day and 40 hourwork week for a given substance to which

it is believed that nearly all workers maybe repeatedly exposed on a daily basiswithout suffering ill effects.

Ceiling: the concentration of a givensubstance that should not be exceeded atany point during an exposure period.


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NIOSH categories of respirators

Class N (not oil resistant): respirators may be used only inenvironments that contain no oil based particulates. They may beused in atmospheres that contain solids or non oil contaminants.

Class R (Oil resistant): respirators may be used in atmospherescontaining any contaminant. However the filters in Class Rrespirators must be changed after each shift if oil based

contaminants are present. Class P (oil proof): respirators may be used in any atmosphere

containing any particulate contaminant.

If there is any question about the viability of an air filtering respiratorin a given setting, employees should use air supplying respirators.

Air from the air is completely blocked out, and fresh air is provided

via a self contained breathing apparatus.


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Sick building syndrome

A sick building is one that makes people sick because ithas become infested with mold, mildew, spores, andother airborne micro organisms.

Poor indoor air quality (IAQ) can cause a variety of

health problems ranging from the temporary to the longterm.

One of the keys in preventing sick building syndrome isair exchange.

Important factors in a buildings ability to eliminatecontaminated air and bring in fresh air are: ventilation, airinfiltration rates, airflow rates in ducts, airflow patterns,and fume exhaust.


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OSHA confined space standard

The OSHA confined space standard (29 CFR 1910.146)mandates that entry permits be required beforeemployees are allowed to enter a potentially hazardousconfined space.

Before the permit is issued a supervisor, safety or healthprofessional, should do the following: shut downequipment/power (locked/tagged), test the atmosphere(19.5 to 23.5% oxygen), ventilate the space, have rescuepersonnel stand by, maintain communication, and use a

lifeline (can pull an unconscious employee out of aconfined space).


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OSHA hazard communication

standard (29 CFR 1910.1200)

Any organization that uses hazardous

material in the workplace is required to

fully inform employees and on-site

contractors of the hazards and to providetraining concerning the safe handling,

storage, and use of the materials.


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Home work

Answer questions 4, 9, 11, 16, 17, 26, 29, 30, 31, and 33 on page 477. 4. List 5 OSHA requirements relating to industrial hygiene.

9. Summarize the various elements of ANSI Z9.8 (indoor air quality/HVAC).

11. What type of medical examinations should be required of employeeswho handle ACMs (Asbestos Containing Materials).

16. Explain 5 self protection strategies that employees can use in the

workplace. 17. How does NIOSH relate to industrial hygiene?

26. Describe the basic provisions of the following standards: OSHAChemical Process Standard, EPA Clean Air Act, and SARA.

29. Explain the 3 NIOSH categories of respirators.

30. What is sick building syndrome?

31. Explain the major tenets of the OSHA Confined Space Standard. 33. Summarize the requirements of OSHAs Hazard Communication

Standard.

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