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Sources of Indoor Air Pollution - Nitrogen Dioxide (NO2)
The two most prevalent oxides of nitrogen
are nitrogen dioxide (NO2) and nitric oxide (NO).
Both are toxic gases with NO2 being a
highly reactive oxidant and corrosive.Definition
Properties: A red-brown gas or yellow liquid; becomes
colorless solid at -11.2oC, which exists in varying equilibrium
with other oxides of nitrogen as the temperature is varied. A component
of automotive exhaust fumes. M.p. (liquid) -9.3oC; b.p. (gas)
21oC. Noncombustible. Derivation: By oxidation
of nitric acid, an intermediate stage in the oxidation of ammonia to nitric
acid. Hazard: Highly toxic; inhalation may be fatal.
Tolerance, 5 ppm in air. Can react strongly with reducing materials.
Source: "The Condensed Chemical Dictionary," 9th ed., revised by Gessner
G. Hawley, Van Nostrand Reinhold Co., NY, 1977.
Sources of Nitrogen Dioxide
Kerosene heaters, un-vented gas
stoves and heaters. Environmental tobacco smoke.
Health Effects Associated with Nitrogen
Dioxide
Eye, nose, and throat
irritation. May cause impaired lung function and increased respiratory
infections in young children. EPA's Integrated Risk Information System
profile for Nitrogen Dioxide - epa.gov/iris/subst/0080.htm
Levels in Homes
Average level in homes
without combustion appliances is about half that of outdoors. In homes with gas
stoves, kerosene heaters, or un-vented gas space heaters, indoor levels often
exceed outdoor levels.
Steps to Reduce Exposure
(These are the
same steps as those used to reduce exposure to carbon
monoxide).
- Keep gas appliances properly adjusted.
- Consider purchasing a vented space heater when
replacing an un-vented one.
- Use proper fuel in kerosene space heaters.
- Install and use an exhaust fan vented to
outdoors over gas stoves.
- Open flues when fireplaces are in use.
- Choose properly sized wood stoves that are
certified to meet EPA emission standards. Make certain that doors on all
wood stoves fit tightly.
- Have a trained professional inspect, clean,
and tune-up central heating system (furnaces, flues, and chimneys) annually.
Repair any leaks promptly.
- Do not idle the car inside garage.
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From the IAQ Tools for Schools Kit - IAQ Coordinator's Guide -
www.epa.gov/iaq/schools/tfs/guidee.html
| Description |
Sources |
Standards
or Guidelines |
| The two most prevalent oxides of nitrogen
are nitrogen dioxide (NO2) and nitric oxide (NO).
Both are toxic gases with NO2 being a
highly reactive oxidant and corrosive. |
The primary sources indoors are
combustion processes, such as unvented combustion appliances, e.g. gas stoves, vented
appliances with defective installations, welding,
and tobacco smoke. |
No standards have been agreed upon for
nitrogen oxides in indoor air. ASHRAE and the US.
EPA National Ambient Air Quality Standards list
0.053 ppm as the average 24-hour limit for
NO2 in outdoor air. |
| Health
Effects |
Control
Measures |
| NO2 acts mainly as an irritant affecting
the mucosa of the eyes, nose, throat, and
respiratory tract. Extremely high-dose exposure (as in
a building fire) to NO2 may result in
pulmonary edema and diffuse lung injury.
Continued exposure to high NO2 levels can contribute to
the development of acute or chronic bronchitis.
Low level NO2 exposure may cause
increased bronchial reactivity in some asthmatics, decreased lung function in patients with
chronic obstructive pulmonary disease and increased
risk of respiratory infections, especially in
young children. |
Venting the NO2 sources to the outdoors,
and assuring that combustion appliances are
correctly installed, used, and maintained are the
most effective measures to reduce exposures. |
Additional Resources
Office of Air and Radiation page -
" NOx - How Nitrogen
Oxides Affect the Way We Live and Breathe"
Maine's Department of Environmental Protection's
BEAM Chemical Fact Sheet on Nitrogen Dioxide
What You Should
Know About Combustion Appliances and Indoor Air Pollution
Answers commonly-asked questions about the
effect of combustion appliances (e.g., fuel-burning furnaces, space heaters,
kitchen ranges, and fireplaces) on indoor air quality and human health.
Describes other sources of combustion pollutants in and around the home.
Suggests ways to reduce exposure to such pollutants and encourages proper
installation, use, and maintenance of combustion appliances. This brochure was
coauthored with the U.S. Consumer Product Safety Commission and the American
Lung Association. [EPA 400-F-91-100, 1993]
Indoor Air
Pollution: An Introduction for Health Professionals
Assists health professionals (especially the
primary care physician) in diagnosis of patient symptoms that could be related
to an indoor air pollution problem. Addresses the health problems that may be
caused by contaminants encountered daily in the home and office. Organized
according to pollutant or pollutant groups such as environmental tobacco
smoke, VOCs, biological pollutants, and sick building syndrome, this booklet
lists key signs and symptoms from exposure to these pollutants, provides a
diagnostic checklist and quick reference summary, and includes suggestions for
remedial action. Also includes references for information contained in each
section. This booklet was coauthored with the American Lung Association, the
American Medical Association, and the U.S. Consumer Product Safety Commission.
[EPA 402-R-94-007, 1994]
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