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
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
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