Carbon Monoxide

Carbon Monoxide(CO) is an odorless, colorless, and toxic gas. Carbon Monoxide fumes are impossible to see, taste, or smell. Carbon Monoxide 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.


Potential sources of Carbon Monoxide (CO)

  • Unvented kerosene and gas space heaters
  • Leaking chimneys and furnaces
  • Back-drafting from furnaces
  • Gas water heaters
  • Wood stoves
  • Fireplace
  • Gas stoves
  • Generators and other gasoline powered equipment
  • Automobile exhaust from attached garages
  • 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 And 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.

Carbon Monoxide Levels In The Home

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. The U.S. Consumer Product Safety Commission (CPSC) recommends that every home should have a carbon monoxide (CO) alarm. CPSC also urges consumers to have a professional inspection of all fuel burning appliances, including:
  • Furnaces
  • Stoves
  • Fireplaces
  • Clothes dryers
  • Water heaters
  • Space heaters
to detect deadly carbon monoxide leaks. CPSC recommends that every home should have at least one CO alarm that meets the requirements of the most recent Underwriters Laboratories(UL) 2034 standard or International Approval Services 6-96 standard.

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.

What Do You Do In The Event of a Carbon Monoxide Emergency?

Immediately get OUT of the contaminated environment and into fresh air. Call your local Fire Department immediately. Do not try to go back into the contaminated environment to retrieve items or to attempt rescue of others inside. At higher levels Carbon Monoxide and overcome you quickly, resulting in confusion, unconsciousness and/or death. Special breathing apparatus like that used by firefighters must be worn when entering these environments.

Additional Resources

  • To report a dangerous product or a product-related injury, call the Consumer Product Safety Commission's (CPSC) hotline.
    • Phone: (800) 638-2772
    • Teletypewriter: (800) 638-8270
  • To obtain recall information from CPSC visit
  • To report product hazards send an e-mail to
  • To learn more about Carbon Monoxide visit the EPA's Carbon Monoxide page at