Customers should be aware that CO is not just in the furnace, as some would have you believe. In fact most CO fatalities are not related to equipment in the home, but to cars and trucks and other kinds of vehicles. While we agree that carbon monoxide can be a problem in the home, its risk should not be overstated. Concentrations are measured in parts of CO per million parts of oxygen. The alarm warns you to ventilate the area and to search for the poison's source.
Some detectors sound alarms intermittently until the air level is safe.
Consult the public library for published consumer reviews. Parts Per Million Responses 25 Permissible exposure level, no apparent toxic symptoms. No poisoning for long period. Allowable for several hours. 200 Should not be exposed above this level for any period of time.