ObjectiveStarting new unit: Risk & Toxicology
Identify types and sources of indoor air pollution.
Explain how indoor air pollutants affect human health.
Describe ways to reduce indoor air pollution.
Read the passage…
Why is indoor air quality important?
Levels of common pollutants are generally higher indoors
70 to 90% of time spent indoors home, work, school, cars
Many significant pollution sources in the home gas cookers, paints, glues
Personal exposure to many common pollutants is driven by indoor exposure... May lead to cancer & other ailments.
Especially important for susceptible groups: sick, old, very young, pregnant women, smokers, people
with respiratory/heart problems, factory workers
Respiratory System Defense:
Nose hairs Mucus Sneezing/coughing Cilia (line upper respiratory tract)
Broken down by smoking, causing Lung cancer Asthma Chronic bronchitis Emphysema
Humans Die from Pollution Annually, U.S. estimates 65,000-200,000
premature deaths from outdoor pollution Indoor pollution included: 150,000-350,000
premature deaths Worldwide: 2.7 million premature deaths Millions more face illness
House of Commons Select Committee Enquiry on Indoor Air Pollution (1991)
“[There is] evidence that 3 million people have asthma in the UK… and this is increasing by 5% per annum.”
“Overall there appears to be a worryingly large number of health problems which could be connected with indoor pollution and which affect very large numbers of the population.”
[The Committee recommends that the Government] “develop guidelines and codes of practice for indoor air quality in buildings which specifically identify exposure limits for an extended list of pollutants…”
Top Dangerous Pollutants According to the EPA, 3 most dangerous
indoor air pollutants: Cigarette smoke Formaldehyde (colorless, extremely irritating gas;
used to manufacture many household materials) Radioactive Radon-222 Gas
Additionally: Asbestos Burning candles indoors Tiny fibers of fiberglass (potentially potent
carcinogen)
Sources of Indoor Air Pollutants
Building materials Furniture Furnishings and
fabrics Glues Cleaning products Combustion applian
ces (cookers and heaters)
Other consumer products
Open fires Tobacco smoking Cooking House dust mites,
bacteria and moulds Outdoor air
Sick Building Syndrome A persistent set of symptoms in >20%
population Headaches Fatigue Reduced Mentation Irritability Eye/nose/throat irritation
Cause(s) not known or recognizable Complaints/Symptoms relieved after
exiting building
Dry Skin Nasal Congestion Difficulty Breathing Nose Bleeds Nausea
Building Related Illness Clinically recognized disease (different from “sick building”) Exposure to indoor air pollutants Recognizable Causes
Pontiac Fever – Legionella spp. Legionnaire's Disease Hypersensitivity Pneumonitis Humidifier Fever Asthma Allergy Respiratory Disease Chronic Obstructive Pulmonary Disease
Important Indoor Air pollutants
Nitrogen dioxide Carbon monoxide Formaldehyde Asbestos Volatile Organic Compounds (VOCs) House dust mites (and other allergens, e.g. from
pets) Environmental tobacco smoke Fine particles Radon Chlorinated organic compounds (e.g. pesticides) Asbestos and man-made mineral fibres
Health Effects
Nitrogen dioxide (criteria pollutant) Respiratory irritant Elevated risk of respiratory illness in
children, perhaps resulting from increased susceptibility to respiratory infection; inconsistent evidence for effects in adults
Concentrations in kitchens can readily exceed WHO and EPA standards
Health Effects
Carbon monoxide (criteria pollutant) An asphyxiant and toxicant Impairs perception, slows reflexes,
headaches, drowsiness Hazard of acute intoxication, mostly from
malfunctioning fuel-burning appliances and inadequate or blocked flues
Possibility of chronic effects of long-term exposure to non- lethal concentrations, particularly amongst susceptible groups
Health Effects
Formaldehyde Sensory and respiratory irritant and
sensitizer Possible increased risk of asthma and
chronic bronchitis in children at higher exposure levels
Individual differences insensory and other transient responses
Health Effects
Volatile Organic Compounds (VOCs) Occur in complex and variable mixtures Main health effects relate to comfort and
well-being, but benzene (and other VOCs) are carcinogenic
Concern about possible role of VOCs in the aetiology of multiple chemical sensitivity; also implicated in sick building syndrome
Health Effects
House dust mites House dust mites produce Der p1 allergen, a
potent sensitizer Good evidence of increased risk of
sensitization with increasing allergen exposure, but this does not necessarily lead to asthma
Small reductions in exposure will not necessarily lead to reduced incidence and/or symptoms
Indoor humidity is important
Health Effects
Fungi and bacteria Dampness and mould-growth linked to self-
reported respiratory conditions, but little convincing evidence for association between measured airborne fungi and respiratory disease
Insufficient data to relate exposure to (non-pathogenic) bacteria to health effects in the indoor environment
Health Effects
Environmental tobacco smoke (ETS)
Sudden infant death syndrome
Lower respiratory tract illness
Middle ear disease Asthma 12 million children
exposed to secondhand smoke in homes
Health Effects
Fine particles (criteria pollutant) Consistent evidence that exposure to small
airborne particles (e.g. PM10) in ambient air can impact on human health; mechanisms uncertain
Chronic Obstructive Pulmonary Disease and Cardiovascular Disease patients and asthmatics probably at extra risk
Relative importance of indoor sources is unknown
Airborne Particulates Examination Take a particulate strip home to place next to your
bed. Compare with school in 3 days. With your group of 3:
Choose an area in the school Label your particulate strip Place your particulate strip Take a picture of your filled out, placed particulate strip
Partner Roles: Scribe Installer Photographer
Predict! Which location in the school do you think will
have the poorest air quality? Do you think the particulate strip next to your
bed will be the same, better, or worse?
Health EffectsRadon Naturally formed from the decay of uranium
55% of our exposure to radiation comes from radon
Colorless, tasteless, odorless gas Found in nearly all soils (levels vary) Seeps upward through soil and quickly dispersesto harmless levels outdoors BUT, indoors…
Radon: How it Enters Buildings
1. Cracks in solid floors2. Construction joints3. Cracks in walls4. Gaps in suspended
floors5. Gaps around service
pipes6. Cavities inside walls7. The water supply
http://www.epa.gov/iaq/radon/pubs/citguide.html#howdoes
Radon Risk: Non-SmokerRadon Level
(pCI/L)If 1000 people who did not smoke were
exposed to this level over a lifetime.. About X would get lung cancer
This risk of cancer from radon exposure compares
to …What to do:
20 8 Being killed in a violent crime
Fix your home
10 4 Fix your home
8 3 10x risk of dying in a plane crash
Fix your home
4 2 Risk of drowning Fix your home
2 <1 Risk of dying in a home fire
Fix your home
1.3 <1 Average indoor radon level Fix your home
.4 <1 Average indoor radon level Fix your home
If you are a former smoker, your risk may be higher
Radon Risk: SmokerRadon Level
(pCI/L)If 1000 people who smoke were
exposed to this level over a lifetime.. About X would get lung cancer
This risk of cancer from radon exposure compares
to …
What to do:Stop smoking and
…20 135 100x risk of drowning Fix your home
10 71 100x risk of dying in a home fire
Fix your home
8 57 Fix your home
4 29 100x risk of dying in a plane crash
Fix your home
2 15 2x the risk of dying in a car crash
Fix your home
1.3 9 Average indoor radon level Fix your home
.4 3 Average indoor radon level Fix your home
If you are a former smoker, your risk may be lower
Radon: Reducing the Risks
Sealing cracks in floors and walls
Simple systems using pipes and fans
Test indoor air & compare with EPA’s acceptable levels
More information
Reducing Indoor Air Pollutants Using simple stoves that burn more efficiently
(reduces deforestation) Using simple solar cookers Breathing wall
Absorbs indoor dirty air Exhales clean air
Improve ventilation
Ventilation Movement of Air Into / Out of Homes Amount of air available to dilute pollutants
important indicator of the likely contaminant concentration
Indoor air can mix with outside air by three mechanisms infiltration natural ventilation forced ventilation
VentilationInfiltration
natural air exchange that occurs between a building and its environment when the doors and windows are closed leakage through holes or openings in the building pressure induced
Due to pressure differentials inside and outside of the building
Especially important with cracks and other openings in wall
Ventilation Natural ventilation
air exchange that occurs when windows or doors are opened to increase air circulation
Forced ventilation mechanical air handling systems used to
induce air exchange using fans and blowers
Trade-offs cut infiltration to decrease heating and
cooling costs vs. indoor air quality problems
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