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Carbon Monoxide (CO)
Carbon monoxide is an odorless, colorless and toxic gas. Because it
is impossible to see, taste or smell the toxic fumes, CO can kill you
before you are aware it is in your home. At lower levels of exposure, CO
causes mild effects that are often mistaken for the flu. These symptoms
include headaches, dizziness, disorientation, nausea and fatigue. The
effects of CO exposure can vary greatly from person to person depending
on age, overall health and the concentration and length of exposure.
Contents
Definition
Carbon monoxide (CO) is a colorless, practically odorless, and
tasteless gas or liquid. It results from incomplete oxidation of
carbon in combustion. Burns with a violet flame. Slightly
soluble in water; soluble in alcohol and benzene. Specific
gravity 0.96716; boiling point -190oC; solidification
point -207oC; specific volume 13.8 cu. ft./lb. (70oF).
Auto ignition temperature (liquid) 1128oF. Classed as
an inorganic compound.
Source: "The Condensed Chemical Dictionary," 9th ed.,
revised by Gessner G. Hawley, Van Nostrand Reinhold Co., NY, 1977.
Sources of Carbon Monoxide
Unvented kerosene and gas space heaters; leaking chimneys and
furnaces; back-drafting from furnaces, gas water heaters, wood stoves,
and fireplaces; gas stoves; generators and other gasoline powered
equipment; automobile exhaust from attached garages; and tobacco
smoke. Incomplete oxidation during combustion in gas ranges and
unvented gas or kerosene heaters may cause high concentrations of CO
in indoor air. Worn or poorly adjusted and maintained combustion
devices (e.g., boilers, furnaces) can be significant sources, or if
the flue is improperly sized, blocked, disconnected, or is leaking.
Auto, truck, or bus exhaust from attached garages, nearby roads, or
parking areas can also be a source.
Health
Effects Associated with Carbon Monoxide
At low concentrations, fatigue in healthy people and chest pain in
people with heart disease. At higher concentrations, impaired vision
and coordination; headaches; dizziness; confusion; nausea. Can cause
flu-like symptoms that clear up after leaving home. Fatal at very high
concentrations. Acute effects are due to the formation of
carboxyhemoglobin in the blood, which inhibits oxygen intake. At
moderate concentrations, angina, impaired vision, and reduced brain
function may result. At higher concentrations, CO exposure can
be fatal.
Levels in Homes
Average levels in homes without gas stoves vary from 0.5 to 5 parts
per million (ppm). Levels near properly adjusted gas stoves are often
5 to 15 ppm and those near poorly adjusted stoves may be 30 ppm or
higher.
Steps to
Reduce Exposure to Carbon Monoxide
It is most important to be sure combustion equipment is maintained
and properly adjusted. Vehicular use should be carefully managed
adjacent to buildings and in vocational programs. Additional
ventilation can be used as a temporary measure when high levels of CO
are expected for short periods of time.
- Keep gas appliances properly adjusted.
- Consider purchasing a vented space heater when replacing an
unvented 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.
Measurement Methods
Some relatively high-cost infrared radiation adsorption and
electrochemical instruments do exist. Moderately priced
real-time measuring devices are also available. A passive
monitor is currently under development.
Standards or Guidelines
No standards for CO have been agreed upon for indoor air. The
U.S. National Ambient Air Quality Standards for outdoor air are 9 ppm
(40,000 micrograms per meter cubed) for 8 hours, and 35 ppm for 1
hour.
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