Frequent Questions

What is the average level of carbon monoxide in homes?

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.

For more informaton on carbon monoxide, see www.epa.gov/iaq/co.html

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