Indoor Air Pollution - Overview
People spend most of their time indoors.
The EPA has shown that indoor levels of some
pollutants, such as formaldehyde, chloroform,
and styrene, range from 2 to 50 times higher
than outdoor levels.
Exposure to pollutants such as environmental
tobacco smoke and radon occurs almost
Indoor Air Pollution
1) toxic gases
e.g. carbon monoxide, ozone, formaldehyde
2) particulate matter
e.g. candles, incense, smoke, pet dander
3) radiogenic species
e.g. Radon-220, Polonium-210
4) biological organisms
e.g. mold, dust mites, bacteria
Some Specific Indoor Air Pollutants
Acetone - in cosmetics, fragrances, human breath
Ammonia - in cleaning products
Benzene - in laser printers, particle board, paint, tobacco
Benzaldehyde - in detergents and fragrances
Benzyl acetate - in air fresheners, fragrances
Chloroform - in chlorinated tap water
Formaldehyde - in particle boards, carpets, clothes, glue
Limonene - in deodorants, disinfectants, fragrances
Terpinen - in deodorants, fragrances
Toulene - in glue, laser printers, paint and particle board
Trichloroethyl - in photocopiers
Xylene - in glue, laser printers, paint and particle board
EPA’s Stance on Ozone
ozone generators are not effective at removing
many of the most harmful chemicals--including
carbon monoxide and formaldehyde--commonly
found in indoor environments.
for many of the chemicals with which ozone does
readily react, ozone forms a variety of harmful or
irritating by-products, including aldehydes and
other organic chemicals.
ozone does not remove particles (such as dust and
pollen) from the air.
Coverage - up to 2,000 square feet
Maximum Ozone Output - 750 mg/hr
Ozone Generator - http://www.purennatural.com
The “Ozone Zapper”- According to Specs
With “perfect mixing”, the maximum output
rate (750 mg/hr) combined with the maximum
area coverage (2,000 ft2) gives an ozone
production rate of 920 ppb/hr.
Ozone concentrations will be greater near the
“Ozone Zapper” source.
920 ppb O3 is more than 10 times the EPA’s
Lead Particulates - Candle Burning
The core of candle wicks may contain lead.
Out of the molten wax, lead can be emitted as
particulate to the air.
In an EPA study, of 100 sets of candles that
appeared to have metal-core wicks, 8%
contained lead wicks.
Environmental Tobacco Smoke (ETS)
The EPA has classified environmental
tobacco smoke as a class A carcinogen,
responsible for approximately 3,000
lung cancer deaths and 62,000 heart
disease deaths annually in U.S. non-
ETS includes toxic gases, particulate
matter and radiogenic species.
Among the powerful poisons in
Environmental Tobacco Smoke (ETS) are:
Among the carcinogens in ETS are:
Benzo [a] pyrene
A colorless, odorless, invisible radioactive gas,
is released into the air from the uranium found
naturally in rocks and soil.
Radon Exposure – EPA Guidelines
EPA Standard for Radon = 4 pCi/L
Out of 1,000 people exposed to 4 pCi/L over a
lifetime, 2 non-smokers and 29 smokers are
predicted to get lung cancer.
Smoking and radon gas exposure show a
synergistic relationship with respect to lung
“A bacterial disease commonly
associated with water-based
aerosols and often a result of
poorly maintained air
conditioning cooling towers
and potable water systems.”
Cases have been reported in
the US, Australia, Netherlands,
These microscopic insects excrete
proteins that can trigger asthma
and allergy attacks in people.
“Typical places to find
mites are the mattress, and
the carpeting next to the
bed, because the bed is
where we spend the
majority of our time -- at
least 8 hours a day
sleeping, so we lose a lot of
skin cells there,” said Glass.
“The average person sheds
enough skin cells every day
to feed thousands of mites
for a month.”
Indoor Pollution Transport
Indoor to Outdoor, Outdoor to Indoor
Transport (basic methods/terminology)
How do you improve indoor air pollution
- air moves through opened
windows and doors.
(Air movement associated with
infiltration and natural ventilation is
caused by air temperature
differences between indoors and
outdoors and by wind.)
Transport - Continued
- 1.outdoor-vented fans that
intermittently remove air from a single
- 2. air handling systems that use
fans and duct work to continuously
remove indoor air and distribute filtered
and conditioned outdoor air to strategic
points throughout the house.
The rate at which outdoor air replaces
indoor air is described as the air
exchange rate. When there is little
infiltration, natural ventilation, or
mechanical ventilation, the air
exchange rate is low and pollutant
levels can increase.
eliminate individual sources of pollution or to
reduce their emissions.
- seal or enclose (asbestos)
- adjust to decrease the amount of
In many cases, source control is also a more
cost-efficient approach to protecting indoor air
quality than increasing ventilation because
increasing ventilation can increase energy
increase the amount of outdoor air
- Opening windows and doors,
operating window or attic fans, when the
weather permits, or running a window air
conditioner with the vent control open
increases the outdoor ventilation rate.
Ventilation - Continued
important to take as many of these
steps as possible while you are involved
in short-term activities that can generate
high levels of pollutants.
- painting, paint stripping, heating
with kerosene heaters, cooking, or
engaging in maintenance and hobby
activities such as welding, soldering, or
many types and sizes of air cleaners on the
- ranging from relatively inexpensive table-
top models to sophisticated and expensive
Some are highly effective at particle removal,
while others, including most table-top models,
are much less so.
Air cleaners are generally not designed to
remove gaseous pollutants.
Air Cleaners - Continued
The effectiveness of an air cleaner depends
on how well it collects pollutants from indoor
air and how much air it draws through the
cleaning or filtering element.
A very efficient collector with a low air-
circulation rate will not be effective, nor will a
cleaner with a high air-circulation rate but a
less efficient collector.
The long-term performance of any air cleaner
depends on maintaining it according to the
Another important factor in determining
the effectiveness of an air cleaner is the
strength of the pollutant source.
Table-top air cleaners may not remove
satisfactory amounts of pollutants from
strong nearby sources.
Some Chemical Air Pollutants
Some Volatile Organic Compounds
Compound Health Effects
Benzene Carcinogen; respiratory tract irritant
Xylenes Narcotic; irritant; affects heart, liver, kidney, and
Toluene Narcotic; possible cause of anemia
Styrene Narcotic; affects control of nervous system; probable
Toluene diisocyanate (TDI) Sensitizer; probable human carcinogen
Trichlaroethane Affects central nervous system
Ethyl benzene Severe irritation of eyes and respiratory tract; affects
central nervous system
Dichloromethane Narcotic; affects nervous system; probable human
1.4-Dichlorobenzene Narcotic; affect liver, kidney, and central nervous
system; eye and respiratory tract irritant
Benzyl chloride Central nervous system depressant; affects liver and
kidney; eye and respiratory tract irritant
2-Butanone (MEK) Irritant; central nervous system depressant
Petroleum distillates Affects central nervous system, liver, and kidneys
4-Phenylcyclohexene Eye and respiratory tract irritant; central nervous
Source: U.S. Environmental Protection Agency (EPA). Introduction to Indoor Air Quality. Report no. EPA/400/3–91/ 003, Washington, DC: U.S.
Environmental Protection Agency, 1991.
Reaction between -pinene and O3
Source: The significance of secondary organic aerosol formation and growth in buildings: experimental and computational evidence
Golam Sarwar, Richard Corsi, David Allen and Charles Weschler
The Bigger Picture: Impacts on
Americans spend majority of their
day in an indoor environment.
Other cultures can spend more/less
Health Effects - Respiratory
Physiology affords a
Direct pathways to
Although low in tidal
volume, high in
liter/day = 6900 m3/day
(= 13.2 kilogram at PM10
standard of 75mg over
Health Effects - Cardiac
Peters et al. – strong
elevation and PM2.5
Acid deposition (gas
and particle) and
linkage to cardiac
Biogenic Air Pollutants
Chew et al. – Cockroach allergen and
sensitivity to Asthma
Consistent 8-10 hour exposure to
Adequacy of Monitoring
Debatable whether or
not EPA monitors reflect
magnitude of exposures
– monitors generally
deployed near industrial
facilities to monitor
currently best way to
(although far from
perfect – “personal
The Comforts of Home
Tolerance for ETS
A Special Health Concern:
Stress decreased job performance,
missed time at work/school, etc.
Oxidants decaying possessions (i.e.
artwork, food products)
Summary and Conclusions
Heterogeneous, numerous, etc.
Not uniform throughout homes, critical to
Both oxidizing and reducing environments, wider
array of chemical species
Health and other effects widespread, largely due
to “comforts of home”.
Burge, H. Bioaerosols: Prevalence and Health Effects in the Indoor Environment. J Allergy and Clin
Immunology: 86:5, 687-702, 1990.
Clean Air Amendments of 1970, Public Law 91–604, 84 Statute, December 31,1970. Air Standards
Authorization implemented by U.S. Environmental Protection Agency, Washington, DC, April 30, 1971.
Chew G; Stelmach I; Jerzynska J; Stelmach W; Majak P; Gorski P; Kuna Cockroach allergy and exposure to
cockroach allergen in Polish children with Asthma. Allergy, 2002 Aug, 57(8):701-5
Munir, A., Kjellman, M., Bjorksten, B. Exposure to Indoor Allergens in Early Infancy and Senstization. J
Allergy and Clin Immunology. 100:2, 177-181, 1997.
Peters, A., D. Dockery, et al. (2001). "Increased Particulate Air Pollution and the Triggering of Myocardial
Infarction." Circulation 103: 2810-2815.
Ritchie, Ingrid.; Martin, Stephen John. The Healthy Home Kit : Inspecting for Environmental Hazards, Working
With Professionals to Avoid Risks, Cleaning Up Radon, Lead, Asbestos, and More!
U.S. Environmental Protection Agency (EPA). Introduction to Indoor Air Quality. Report no. EPA/400/3–91/
003, Washington, DC: U.S. Environmental Protection Agency, 1991.
U.S. Environmental Protection Agency, Indoor Air Pollution: An Introduction for Health Professionals, No. 1994-