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Description

Carbon monoxide (CO) is a colorless, odorless, poisonous gas that is produced whenever any fuel such as gasoline, fuel oil, natural gas, kerosene, wood, coal, or charcoal is burned. Carbon monoxide is one of the major combustion pollutants that can contaminate indoor and outdoor air.

Indoors, CO is emitted by unvented and improperly maintained gas appliances (kerosene and gas space heaters, furnaces, water heaters, stoves), woodstoves and fireplaces, and tobacco smoke. Automobile exhaust, a major source of CO, can seep into homes from attached garages or into vehicle compartments.

CO can accumulate very rapidly indoors. At high levels, carbon monoxide can be fatal within minutes. Hundreds of people die accidentally every year from CO poisoning caused by malfunctioning or improperly used fuel-burning appliances and idling cars. Low levels of CO can also cause health effects and trigger asthma.

Infants and young children, the elderly, smokers, and individuals with anemia or respiratory diseases such as asthma are also particularly sensitive to CO exposure. Exposure to CO during pregnancy can result in the exposure and harm of the fetus.

Health Effects

Immediate Health Effects

If SWALLOWED, carbon monoxide is Not Available
If ABSORBED THROUGH SKIN, carbon monoxide is Not Available
If INHALED (SNIFFED OR BREATHED IN), carbon monoxide is Not Available

Longterm or Delayed Health Effects

Neurotoxin = Can harm brain and central nervous system
Asthma Trigger
Development Toxicant = Can interfere with normal development of a fetus or child

Other

Inhaling carbon monoxide, even at low levels, can cause headache, fatigue, queasiness, nausea, vomiting, dizziness, difficulty concentrating, memory and vision problems, confusion and incoordination. Because some of these symptoms resemble the flu, CO poisoning victims are often not correctly diagnosed, sometimes leading to death.

Even low levels of carbon monoxide can cause chest pain in persons with heart disease. Carbon monoxide exposure can cause cardiovascular arrhythmia and cardiomyopathy. Infants and young children, the elderly, smokers, and individuals with anemia or respiratory diseases such as asthma are also particularly sensitive to CO exposure.
High levels of CO can cause severe headache, brain and heart damage, convulsions, unconsciousness and death.
Repeated exposure may increase the risk for heart disease and damage the brain and central nervous system.
Birth defects and stillbirth. Carbon monoxide readily crosses the placenta. Exposure to high levels of carbon monoxide during pregnancy may increase the risk that the child could be born with brain damage, congenital heart defects, or reduced birth weight, or that it could be stillborn.
Temporary blood damage. Breathing very high levels of carbon monoxide forms carboxyhemoglobin in the bloodstream, which inhibits the ability of the blood to carry oxygen to organs and tissues. This can damage body tissues and organs and cause them to die of a lack of oxygen, resulting in flushing and redness of the skin and mucous membranes, followed by convulsions, coma and death. After exposure has ceased, it may take a long time (around 10 hours) for carboxyhemoglobin levels to return to normal.

How Exposures Occur

Automobile Exhaust

Children can inhale carbon monoxide from car exhaust, particularly in enclosed spaces such as garages, or in houses attached to the garage. When a car is left running in a garage, CO can reach fatal levels inside the garage, even with windows and doors open, and inside rooms adjacent to the garage inside the home. CO poisoning from vehicle exhaust is the most common cause of poisoning deaths in the U.S.

Children are exposed to low levels of CO from breathing outdoor air, with those in high-traffic urban environments likely to breathe in more CO from car exhaust than kids in rural areas.

Gasoline-Powered Tools

Children can inhale dangerous levels of carbon monoxide if they are near gas-powered lawn mowers or power tools that are being used in enclosed areas, even if windows and doors are open.

Paint Strippers

Children can be exposed to carbon monoxide if paint strippers containing methylene chloride are being used nearby. Methylene chloride is readily absorbed through the lungs and is converted to carbon monoxide inside the body.

Smoke From Fires

Children may inhale harmful or fatal levels of carbon monoxide from smoke from fires, including home or building fires, improperly vented fireplaces and wood stoves, and charcoal burned in an enclosed space. Smoke inhalation from all types of fires is the second leading cause of CO poisoning, which causes most immediate deaths from building fires.

Combustion Appliances

Indoors, children can inhale carbon monoxide if the following fuel-burning appliances are not properly maintained or operated: furnaces, unvented kerosene and gas space heaters, gas water heaters, wood stoves, and gas stoves.

Second-Hand Smoke

Tobacco smoke is also a significant source of CO, containing approximately 4% CO. Children can inhale it while in the presence of smokers.

Significant Statistics

Carbon monoxide from vehicle exhaust is the single most common cause of poisoning deaths in the United States.

Varon, J., and P.E. Marik. “Carbon Monoxide Poisoning.” The Internet Journal of Emergency
and Intensive Care Medicine, Vol. 1, No. 2 (1997).

http://www.uam.es/departamentos/medicina/anesnet/journals/ijeicm/vol1n2/articles/co.htm

Approximately 500 people die each year in the U.S. as a result of accidental carbon monoxide poisoning, and about 10,000 others are sent to the emergency room. Of the fatal CO poisonings, approximately 60% are caused by motor vehicle exhaust, and 40% are caused by consumer products, primarily heating systems. Other causes of death include charcoal grills, gas water heaters, gas ranges and ovens, and fuel-burning camping equipment.

Non-Fire Carbon Monoxide Deaths and Injuries Associated With the Use of Consumer Products: Annual Estimates. U.S. Consumer Product Safety Commission, October 2000.http://www.cpsc.gov/LIBRARY/co00.pdf

Nationwide, 81% of all carbon monoxide emissions come from transportation sources, with the largest contribution coming from highway motor vehicles. In high-traffic urban areas, as much as 95% of all carbon monoxide emissions can be attributed to car exhaust.

1995 Air Quality: Status and Trends-Six Principal Pollutants: Carbon Monoxide. U.S.
Environmental Protection Agency, Office of Air and Radiation.
http://www.epa.gov/oar/aqtrnd95/co.html

Due to U.S. Environmental Protection Agency regulations that forced vehicles to be fitted with catalytic converters, which convert carbon monoxide to carbon dioxide, in the 1970s, today’s cars are capable of emitting 90% less carbon monoxide over their lifetimes than their uncontrolled counterparts of the 1960s. As a result, outdoor carbon monoxide levels have dropped, despite large increases in the number of vehicles on the road and the number of miles they travel.

Automobiles and Carbon Monoxide. U.S. Environmental Protection Agency, January 1993.http://www.epa.gov/otaq/consumer/03-co.pdf

Solutions

How to detect carbon monoxide

Carbon Monoxide Monitors, Detectors or Alarms. Because CO is odorless, invisible, tasteless, and non-irritating, it is impossible to detect without a carbon monoxide detector alarm. The U.S. Consumer Product Safety Commission recommends that all homes have at least one CO detector. They are widely available in home and hardware stores. Make sure that the detector you choose meets the requirements of the most recent Underwriters Laboratories (UL) 2034 standard or International Approval Services 6-96 standard. Look for logos for these on the detector or its packaging. Also choose one that has a long-term warranty and that can be easily self-tested and reset to ensure proper functioning. Carbon monoxide detectors should be placed close to sleeping areas in particular. If your home has more than one floor, install monitors on each floor. Good installation spots include outside the kitchen and near doors that exit to a garage.

If your CO detector goes off, you should:

-Make sure it is the CO detector and not a smoke alarm.

-Check to see if any member of your household is experiencing symptoms (see Health Effects, above).

-If they are, get them out of the house immediately and seek medical attention.

-If no one is feeling symptoms, ventilate the home with fresh air and turn off all potential sources of CO.

CO is invisible and odorless, so it’s harder to tell if an alarm is false or a real emergency. If CO poisoning has occurred, it can often be diagnosed by a blood test done soon after exposure.

NOTE: CO alarms are not yet as reliable as smoke alarms. A CO alarm should not substitute for proper maintenance and use of combustion appliances.
Some visible clues that may indicate that carbon monoxide is leaking into your home include:

• rust or water streaks on vents and chimneys

• loose or missing furnace panels

• loose or disconnected vent or chimney connections

• debris or soot falling from inside the chimney, fireplace or appliance

• loose masonry on chimney

• moisture inside of windows.

How to minimize exposure to carbon monoxide

If you experience symptoms that you think could be from CO poisoning, open doors and windows, turn off combustion appliances, leave the house and get fresh air immediately.
Make sure your home is ventilated well when using gas appliances and have gas appliances cleaned inspected annually for leaks and obstructions. For more tips, see Gas Appliances: How to Minimize Pollutants.
Have your car’s exhaust system inspected annually to be sure it has no small leaks, which can result in an accumulation of CO inside your car. If you are driving with your tailgate open, be sure to open vents or windows to increase the flow of air in the car. If the tailgate window is open and the other windows or the vents are closed, CO from the exhaust will be drawn into the car. Avoid sitting in an idling car. If this is necessary, keep windows open at least slightly.
Don’t leave a car or lawnmower engine running in a shed or garage or in other enclosed spaces. Even if the garage door to the outside is open, fumes can build up very quickly in the garage and living area of your home. Also, don’t operate gasoline-powered appliances, engines or tools (mowers, weed trimmers, snow blowers, chain saws, small engines or generators) in enclosed or partly-enclosed spaces.
Minimize your children’s exposure to secondhand tobacco smoke. If you live with children, do not smoke inside your home or permit others to do so. Any smoking should be done outdoors. Do not smoke where children, particularly infants and toddlers, are present, especially in day care centers, nurseries, or other settings where they spend long hours. Do not smoke in the car: The high concentration of smoke in a small, closed compartment substantially increases the exposure to other passengers. If smoking in the home cannot be avoided, open windows and increase ventilation with box or exhaust fans.
Use fireplaces and wood stoves properly and keep flues and chimney clear and clean. For more tips, see Burning Clean: Wood Stoves and Fireplaces and How to Build a Safer Fire.

Alternatives

Heating systems powered by electricity and electrical appliances (as opposed to gas) don’t release CO and other combustion pollutants into indoor. However, some power plants release combustion byproducts into the environment. Choose clean and environmental energy sources, if you have a choice.
If you purchase gas appliances, choose those that vent their fumes outdoors whenever possible. Have them properly installed, and maintain them according to manufacturers’ instructions. When appliances are kept in good working condition, they produce little carbon monoxide.
Power tools and machinery powered by electricity or compressed air (as opposed to gasoline) do not produce carbon monoxide when in use and will not present an inhalation hazard when used in enclosed areas.

For More information

Books, articles, factsheets and reports

Carbon Monoxide. National Safety Council, Environmental Health Center.

http://www.nsc.org/ehc/indoor/carb_mon.htm

American Lung Association Fact Sheet: Carbon Monoxide. The American Lung Association,
September 2000.

http://www.lungusa.org/air/carbon_factsheet99.html

Checklist for the Prevention of Carbon Monoxide (CO) Poisoning. U.S. Centers for Disease Control and Prevention, National Center for Environmental Health, Air and Respiratory Health Branch.

http://www.cdc.gov/nceh/airpollution/carbonmonoxide/checklistprint.htm