INDOOR AIR QUALITY

Mick Gray MRSC. LFOH. ROH

Occupational Hygienist

MWG Associates Ltd Tel:01276709279

Is IAQ Important?

• 30% of newly constructed or remodeled facilities have IAQ problems

• Indoor contaminants are responsible

for half of all illnesses

• Liability issues

Why is there an increase in IAQ problems?

• More time indoors

• More chemical pollutants in buildings

• Tighter buildings and reduced ventilation

• Deferred maintenance

Common Health Effects of Indoor Contaminants

• Eye, nose and throat irritation

• Coughing and sneezing

• Headaches

• Fatigue • Irritability

• Allergies, sinus congestion

• Dizziness

• Difficulty in concentrating

Health Effects Depend on Several Factors

• The contaminant • The amount of the contaminant

present • The length of time a person is exposed

to the contaminant • The vulnerability of the person

Sick Building Syndrome

• Symptoms include eye, nose and throat irritation, headache, allergies, fatigue

• 20% or more of occupants experience same symptoms

• No medically diagnosable symptoms

• Complaints persist for more than two weeks

• Symptoms often lessen after person leaves building

Regulations and Standards

• Health and Safety at Work Etc Act (1974) This Act seeks to protect all persons at work whether employers, employees or members of the general public affected by the work activities.

• The Control of Substances Hazardous to Health (COSHH) Regulations

The COSHH (Control of Substances Hazardous to Health) Regulations deal with the prevention of ill health arising from exposure to hazardous substances

Legislation • Workplace (Health, Safety and Welfare)

Regulations 1992 Ventilation

The regulations require that every enclosed workspace is

ventilated by a sufficient quantity of fresh or purified air. Where

this ventilation is provided by mechanical means, the Regulations

require these mechanical ventilation systems to be maintained

(including cleaned as appropriate) in an efficient state, in efficient

working order and in good repair.

The Approved Code of Practice expands the need for regular

cleaning, testing and maintenance. Suitable records should be

kept.

Supplied air should be clean and free from anything, which may

contaminate it.

Legislation and Guidelines Recirculated air should be adequately filtered to remove impurities

and, to avoid air becoming unhealthy, purified air should have

some fresh air added before being recirculated. Systems should

therefore be designed with fresh air inlets, which should be kept

open.

The fresh air supply rate should not normally fall below 5 to 8 litres

per second, per occupant.

Specifications for cleanliness in terms of surface and airborne counts for bacteria and fungi are given in TM26: 2000 “Hygienic maintenance of office ventilation ductwork”. [Another document (HVAC TR/19 “Internal Cleanliness of ventilation systems”) focuses on cleanliness of duct and gives surface deposit limits for extract, recirculation and supply ductwork]. HVAC has changed its name to Building and Engineering Services Association.

Legislation and Guidelines TM26: 2000 “Hygienic maintenance of office ventilation ductwork”

mainly talks about surface and airborne counts for bacteria and

fungi and these are listed:

Table 2 Classification of air sampling microbial limits

Category Colony forming units/m3

Low <100

Medium > than or equal to 100 but < 1000

High > than or equal to 1000

Table 3 Classification of surface sampling microbial limits

Category Colony forming units per 10cm

Low <10

Medium > than or equal to 10 but <20

High > than or equal to 20

NOTE: There is no mention of any different standards for bacterial

or fungal species.

Legislation and Guidelines

Thermal Comfort

The temperatures during working hours must be

reasonable. This means the temperature should provide

reasonable comfort without the need for special clothing.

The minimum air temperature should be 16C unless the

work involves severe physical activity in which case the

temperature should be at least 13C. Reasonable

comfort is not achieved by air temperature alone and

other factors such as relative humidity and air movement

need to be considered.

How do we get Fresh Air

How do we get Fresh Air

How do we get Fresh Air

How do we get Fresh Air

How do we get Fresh Air

Fresh Air Plenum

How do we get Fresh Air

Pre- Filters

How do we get Fresh Air

Main Bag Filters

How do we get Fresh Air

Chiller Coil

How do we get Fresh Air

Steam Sparge Pipe before heater coil

How do we get Fresh Air

Heat Recovery Section

How do we get Fresh Air

Sound Attenuators

How do we get Fresh Air

Rust in chamber after filters

How do we get Fresh Air

Contamination on Chiller Coil

How do we get Fresh Air

Fan Chamber

How do we get Fresh Air

Supply Duct

How do we get Fresh Air

Extract Duct

How do we get Fresh Air

Badly fitting pre-filter

How do we get Fresh Air

Excessive debris on Louvers

Filtration

Glass Panel G3

Grade 1 & 2 Pleated Panel G4 Synthetic bag filter F5-F7

Rigid bag filter F5-F7 HEPA Filter H10-13 Charcoal Filter

CHEMICALS

Volatile Organic Compounds (VOCs)

• Carbon-containing compounds that evaporate rapidly

• Examples o Benzene o Toluene

o Styrene o Xylene o Ethanol o Acetone o Methyl Ethyl Ketone o Formaldehyde

Volatile Organic Compounds (Sources)

• Paints, stains, varnishes

• Waxes

• Polishes • Solvents

• Pesticides

• Adhesives • Wood preservatives

• Cleansers

• Lubricants

• Air fresheners

• Fuels

• Plastics

• Copy machines, printers

• Tobacco products • Perfumes

• Dry cleaned clothing

Volatile Organic Compounds

Volatile Organic Compounds

Volatile Organic Compounds

Nitric Oxide – derived from vehicle or gas heating exhaust.

Methanol – derived from silicone products and adhesives, also present as

anaerobic metabolism of biomass (Fruit etc.) and landfill decomposition.

n-Butane - derived from refrigerants, household and lighter fuel and aerosol

propellant.

Benzene - Derived from primarily car exhaust and unburnt car fuel and cigarette

smoke.

Ethanol - derived from surface coatings, lacquers, cosmetics, cleaning agents,

detergents, etc.

Acetone – derived from surface coatings, glues and varnish/lacquer solvent

Isopropanol - used in antifreeze compounds, in lotions and cosmetics, and as a

solvent for gums, shellac, and essential oils.

n-Pentane - used as a blowing agent in plastics, aerosol propellant and cleaning

agent.

Volatile Organic Compounds Methyl sulphonyl chloride – This compound is a lachrymator and is possibly the

cause of stinging eyes.

Acetic Acid – derived from food flavourings, dyes, insecticides and photographic

chemicals.

3-Methylhexane, n-Heptane – derived from resins, latex and paints.

2-Methyl 2-propenoic acid methyl ester – used in polyester resins, acrylic

polymers

Isobutane – derived from refrigerants, household and lighter fuel and aerosol

propellant.

Toluene – derived from resins, paints, gums, glues, oils and car exhaust and unburnt

car fuel.

Ethyl Benzene – derived from petrol and paint solvents

m-/p-Xylenes – derived from paint solvents.

Formaldehyde

• Used in plywood, paneling, particleboard, wallboard, fiberglass, adhesives

• Sometimes in ceiling tiles, wallpaper, furniture, draperies, clothing

• Even low levels can cause difficulties in breathing, burning of eyes nose and throat, coughing; a human carcinogen

COMBUSTION PRODUCTS

Combustion Products

• Carbon monoxide (CO) • Oxides of nitrogen (NOx) • Oxides of sulfur (SOx) • Carbon dioxide (CO2) • Polycyclic Aromatic Hydrocarbons (PAH) • Tobacco Smoke components

Carbon Monoxide (CO)

• Colourless, odourless, tasteless poisonous gas

• Produced as a by-product of combustion

• Deprives the body of oxygen by binding to blood hemoglobin and displacing oxygen molecules

Carbon Monoxide

• Symptoms are headache, dizziness, drowsiness and nausea

• Severe exposure results in vomiting, collapse, coma and death

• WEL for 8 hour LTEL 30ppm

• Body systems most affected are the brain, the heart, and the developing fetus

Carbon Monoxide

• Low levels of exposure - more frequent attacks of angina, reduced athletic performance, heart attacks

• Moderate exposures - loss of attentiveness, decreased visual perception, manual dexterity, learning ability and driving ability

• Smoking – cause of the greatest human exposure

Carbon Dioxide (CO2)

• Colorless, odourless, tasteless gas at room temperature

• Present in exhaled human breath

• Combustion by-product • Naturally present in an unpolluted

environment at about 280 - 350 ppm

Carbon Dioxide

• CO2 levels above 800 ppm may indicate inadequate ventilation

• ASHRAE recommended indoor air quality limit for CO2 is 1000 ppm

• WEL for the 8 hour LTEL 5000 ppm

Carbon Dioxide Carbon Dioxide level (ppm) Guidance

280-350 Normal outdoor ambient concentrations

600 Minimal air quality complaints

600-1,000 Less clearly interpreted

1,000 Indicates inadequate ventilation;

complaints such as headaches, fatigue,

and eye and throat irritation will be more

widespread; 1,000 ppm should be used as

an upper limit for indoor levels*

* It should be noted that these levels are only guidelines. If

carbon dioxide levels exceed 1,000 ppm it does not

necessarily indicate that the building is hazardous and should

be evacuated. Rather this level should be used as a guideline

that helps maximize comfort for all occupants.

RESPIRABLE PARTICLES & GASES

Respirable Particles & Gases

• Asbestos

• Fibreglass

• Silica

• Metal dust • Organic dust

o Pollen

o Bacteria and Mould spores

o Paper dust o Organic and vegetable fibres o Carbonaceous material from vehicle exhaust

BIOAEROSOLS

Bioaerosols

• Substances that are living or were released from a living organism

• Examples o Bacteria

o Fungi/Moulds/Yeasts

o Pollen o Viruses

o Dust mites

Dust Mites

Dust Mites

• Microscopic relatives of spiders

• Feed on dead skin scales and other organic debris

• 2,000,000 in an average bed

• Dust mite faeces - a common allergen

• Prefer relative humidity level above 55%

Viruses

• Smallest and simplest of all life forms

• Depend completely on their hosts for reproduction

• Continually undergo evolutionary change

• Examples o Influenza

o HIV

o Rhinovirus

Bacteria

• Single-celled prokaryotic organisms

• Most are very small spheres, rods or filaments

• Reproduce by simple cell division

• Some produce endospores, which are extremely resistant to harsh conditions

• A few require living hosts

Bacteria in Indoor Environments

• Higher concentrations indoors than outdoors

• Majority of bacteria in air are shed from human skin and respiratory tracts

• Examples of infectious bacteria o Legionella spp. o Staphylococcus o Streptococcus

o Mycobacterium tuberculosis

Bacterial Toxins

• Exotoxins o Excreted

o Clostridium botulinum exotoxin - one of the most powerful poisons known

• Endotoxins o Part of cell wall of gram negative bacteria

o Highly toxic – fever, malaise, changes in white blood cell counts, respiratory distress, shock, even death

Mould

Mould? Where??

Mold on ceiling and walls

Mold in a closet

Mould in air duct

Fungi as Food

• Mushrooms

• Soy sauce

• Yeast • Bread

• Cheese

• Wine

• Beer

Mucor species

Penicillium species

Aspergillus niger

Aspergillus fumigatus

Fungal Metabolism

• Enzymes secreted to digest external food sources, which are then absorbed

• Must have adequate moisture available

Metabolic Products

• Carbon dioxide, water, ethanol • Microbial Volatile Organic

Compounds (MVOCs) • Mycotoxins and antibiotics

MVOCs

• VOCs with distinctive offensive odours

• Possibly responsible for some illnesses

• Different compounds emitted on different media

• Type and quantity change with phases of growth

• Highest MVOC production is prior to and during spore production and mycotoxin production

Mycotoxins

• Produced to inhibit or kill competitors

• May cause serious short term and long term health effects

• Over 200 recognized mycotoxins, and many more not yet discovered

• Toxins production varies with the species, the conditions and the substrate

General Health Effects

• Sinus congestion • Sneezing • Coughing, • Eye irritation • Asthma

• Bronchitis • Hypersensitivity pneumonitis

• Infectious diseases, e.g. ringworm, athletes foot, nail infections, Histoplasmosis, Valley Fever

Mycotoxin Health Effects

• Mucous membrane irritation

• Cold and flu symptoms

• Sore throat • Headache

• Fatigue

• Diarrhea

• Skin rashes

• Dizziness

• Nausea

• Immunosuppression

• Birth defects

• Tremors

• Hemorrhaging

• Cytotoxicity

• Hepatotoxicity

• Nephrotoxicity

• Cancer

Aflatoxin

• One of the most potent carcinogens known to man

• Linked to a variety of health problems

• FDA maximum allowable level is 20 ppb

• Produced by some species of Aspergillus

Water-Damaged Ceiling

Water-Damaged Wallpaper

Stachybotrys, Aspergillus and Penicillium in Basement

MOULD SAMPLING

Difficulties in Mould Sampling

• No absolute standards

• Fungus might not be producing spores at the time of sampling

• Spores might be adhering to surfaces rather than airborne

• Spores might not survive impaction

• Spores might not grow on the media used

• Colonies might be overgrown by others and not detected

• Organism might be very slow growing

Types of Mould Sampling

• Bulk samples

• Surface samples - tape

• Surface samples – swab • Surface samples – contact plate

• Air samples using impaction onto agar

• Air samples using spore trap methods

When Sampling Results Indicate Serious Mould Problem

• Total indoor levels are higher than total outdoor levels

• Fungi indoors are different from outdoors or non-complaint areas

• Fungi are allergenic or toxigenic

• Area is likely to be disturbed

• Present or past water or high humidity

Key Remediation Steps

• Correct the moisture problem that led to the mold growth

• Remove all contaminated porous materials o Use proper PPE

o Containment and negative pressure to prevent spread of spores

o Minimize dust production

o Decontamination

Key Remediation Steps (cont.)

• Clean all contaminated non-porous materials o HEPA vacuum

o Disinfectant or soap and water

Monitoring Basic Parameters

• CO

• CO2

• Temperature

• Relative humidity

• Air flow rates

Monitoring Equipment

TSI Q- Trak Grey Wolf IAQ

Casella ICS

Monitoring Equipment

PID for VOCs Dust Monitor Air flow

Hot Wire

Anemometer Surface air

sampler for

Microbiological

activity