What Can Cause a False Carbon Monoxide Alarm?

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Installing and maintaining a carbon monoxide detector is an essential part of protecting your household. Any appliance that uses combustion to produce heat produces small amounts of carbon monoxide gas, but under certain conditions, carbon monoxide gas can accumulate to toxic, even fatal levels. Carbon monoxide detectors work by measuring the concentration of carbon monoxide gas in parts-per-million and by sounding an alarm when gases have reached dangerous levels. It is essential to understand what causes a false alarm in a carbon monoxide detector in order to know when your family is in danger.

Carbon Monoxide Detectors and False Alarms

According to the Environmental Protection Agency, detection technology used in carbon monoxide alarms is still developing and carbon monoxide detectors "are not generally considered to be as reliable as the smoke detectors found in homes today." Laboratory testing carried out by the EPA, Underwriters Laboratories and other groups has indicated that some carbon monoxide alarms sounded when measuring safe levels of carbon monoxide and others failed to sound when measuring toxic levels of carbon monoxide.


The possible causes of a carbon monoxide detector sounding a false alarm are many and varied. Setting aside obvious causes such as design flaws and electronic malfunctions, installing a carbon monoxide detector in an area of high humidity or in rooms that are not heated, such as basements, garages and attics, can cause false alarms. Because all fire-producing appliances produce small and safe amounts of carbon monoxide, installing a detector too close to one of these appliances can cause a false alarm as well. Finally, installing a carbon monoxide detector in an area where it will be exposed to chemical solvents and cleaners, including hairspray and deodorant spray, can cause the detector to trip erroneously.

What to Do

Carbon monoxide detector false alarms are more difficult to identify than smoke detector false alarms; if a smoke detector goes off, it is quite easy to observe whether there is an actual fire in the home or if it is a false alarm. Carbon monoxide, on the other hand, is a colourless and odourless gas, so simple observation is never sufficient for recognising a false alarm. If your carbon monoxide detector sounds, ventilate the room and leave the house, particularly if anyone in the home exhibits the telltale signs of carbon monoxide poisoning such as headaches, nausea, confusion, dizziness and fainting. If the alarm does not stop sounding after ventilating the room, it is best to have a professional examine the room to determine if there is a toxic build-up of carbon monoxide.

Preventive Measures

The EPA stresses that carbon monoxide detectors should never be considered a replacement for proper maintenance of your fire-producing appliances. Maintaining these appliances properly can diminish the possibility of carbon monoxide build-up and thus save you from needing to determine if an alarm is false or not in the first place. Additionally, research the carbon monoxide detector you plan to purchase to see how the product performed in testing by groups such as Consumer Reports and UL. Most importantly, regularly inspect your carbon monoxide detectors to reduce the likelihood of a false alarm.

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