Carbon monoxide (CO) is an odorless,
colorless, deadly gas. It can kill you before you know it because you can't
see it, taste it or smell it. At lower levels of exposure, it can cause
health problems. Some people may be more vulnerable to CO poisoning such as
fetuses, infants, children, senior citizens and those with heart or lung
problems. When CO is breathed in by an individual, it accumulates in the
blood and forms a toxic compound known as carboxyhemoglobin (COHb).
Hemoglobin carries oxygen in the bloodstream to cells and tissues. Carbon
monoxide attaches itself to hemoglobin and displaces the oxygen that the
body organs need.
Carboxyhemoglobin can cause headaches, fatigue, nausea, dizzy spells,
confusion and irritability. Later stages of CO poisoning can cause vomiting,
loss of consciousness and eventually brain damage or death.
Carbon monoxide is a by-product of combustion of fossil fuels. Fumes from
automobiles contain high levels of CO. Appliances such as furnaces, space
heaters, clothes dryers, ranges, ovens, water heaters, charcoal grills,
fireplaces and wood burning stoves produce CO. Carbon monoxide usually is
vented to the outside if appliances function correctly and the home is
vented properly. Problems occur when furnace heat exchanger crack or vents
and chimneys become blocked. Insulation sometimes can trap CO in the home.
The Consumer Product Safety Commission recommends installing at least one
carbon monoxide detector with an audible alarm near the bedrooms. If a home
has more than one story, a detector should be placed on each story.
Be sure the detector has a testing laboratory label.
The following are areas to look for problem sources of CO in the
A forced air furnace is frequently the source of leaks and should be
- Measure the concentration of carbon monoxide in the flue gases.
- Check furnace connections to flue pipes and venting systems to the
outside of the home for signs of corrosion, rust gaps, holes.
- Check furnace filters and filtering systems for dirt and blockage.
- Check forced air fans for proper installation and to assure correct
air flow of flue gases. Improper furnace blower installation can result
in carbon monoxide build-up because toxic gas is blown into rather than
out of the house.
- Check the combustion chamber and internal heat exchanger for cracks,
holes, metal fatigue or corrosion. Be sure they are clean and free of
- Check burners and ignition system. A flame that is mostly yellow in
color in natural gas fired furnaces is often a sign that the fuel is not
burning completely and higher levels of carbon monoxide are being
released. Oil furnaces with similar problems can give off an oily odor.
Remember you can't smell carbon monoxide.
Check all venting systems to the outside including flues and chimneys for
cracks, corrosion, holes, debris, blockages. Animals and birds can build
nests in chimneys preventing gases from escaping.
Check all other appliances in the home that use flammable fuels such as
natural gas, oil, propane, wood or kerosene. Appliances include water
heaters, clothes dryers, kitchen ranges, ovens or cooktops: wood burning
stoves, gas refrigerators.
- Pilot lights can be a source of carbon monoxide because the
by-products of combustion are released inside the home rather than
- Be sure space heaters are vented properly. Unvented space heaters
that use a flammable fuel such as kerosene can release carbon monoxide
into the home.
- Barbecue grills should never be operated indoors under any
circumstances nor should stove tops or ovens that operate on flammable
fuels be used to heat a residence.
- Check fireplaces for closed, blocked or bent flues, soot and debris.
- Check the clothes dryer vent opening outside the house for lint.