Carbon monoxide is a deadly gas. It is a byproduct of some of combustion used to heat a house or propel a car. It is also produced when something (gas, wood, etc.) is burned, for instance to heat water or cook. Proper venting is necessary so that too much carbon monoxide does not build up in the air we are breathing. If you use gas in the house to cook, heat or perform other functions, you should have at least one carbon monoxide alarm in your home. Carbon monoxide (CO) is colorless and odorless, so you cannot detect it with your senses. Too much exposure can cause carbon monoxide poisoning.


Any burning or combustion can produce some carbon monoxide. The amount depends on things like the efficiency of the burn, and the amount in your home is also affected by the ventilation. Some common household sources are gas burning appliances, fireplaces (wood and gas), kerosene or gas space heaters, gas stoves and ovens, furnaces and water heaters. Tobacco smoke is also a source. Vehicle exhaust has carbon monoxide, so an attached garage where vehicles or gas motors (including generators) are run or nearby roads can be a source of carbon monoxide. A small amount is normal, but higher levels or long-term exposure at medium levels can be dangerous.


Carbon monoxide is usually measured in parts per million (ppm). For a healthy adult, over 50 ppm can cause problems with an exposure of 8 hours. For a young person, an elderly person or someone who has other respiratory or heart problems, a lower level may cause problems. At a low level, carbon monoxide poisoning can cause headaches, nausea, shortness of breath and dizziness -- similar to flu symptoms. At higher levels, it can make someone sick more quickly and more severely. Severe carbon monoxide poisoning can cause death.

ppm possible effects
0.5-5 normal in homes without a gas stove
5-15 normal in homes with a well adjusted gas stove
30+ near older appliances or ones that are not well installed
approximately 50-70 and above may experience milder effects - need to improve ventilation and get to fresh air now
150+ get out - effects may include disorientation, loss of consciousness and death - someone exposed at these levels should be checked out by a health professional

Even at the lower, less critical levels, prolonged exposure may cause problems, and it may make other problems, such as a heart condition more severe.

US regulations[1]:

The OSHA standard for workers is no more than 50 ppm for 1 hour of exposure. NIOSH recommends no more than 35 ppm for 1 hour. The U.S. National Ambient Air Quality Standards for CO (established in 1985) are 9 ppm for 8 hours and 35 ppm for 1 hour. The Consumer Product Safety Commission recommends levels not to exceed 15 ppm for 1 hour or 25 ppm for 8 hours [sic].

Safety tipsEdit

  • Install a carbon monoxide detector on each level of the home. You may also want to consider placing them near bedrooms, especially of more vulnerable household members, such as babies, children or the elderly.
  • Test the carbon monoxide detectors approximately each 6 months. Some people use the daylight savings time changes as a reminder to test both carbon monoxide and smoke detector alarms.


