Carbon monoxide is a colorless, odorless gas. It is a by-product of incomplete combustion from fuel burning appliances such as a furnace, water heater or fireplace. The symptoms of long term exposure to low concentrations include slight headaches, fatigue and shortness of breath with only moderate exertion. Continued exposure or high concentrations can result in severe headaches, breathing difficulties, dizziness, confusion, cardiac trauma, brain damage and ultimately, death. To help reduce the risk of exposure to carbon monoxide, fuel burning appliances should be inspected annually by a qualified technician. Recommend that Carbon monoxide detectors be installed near sleeping areas, they can also be installed on or near the ceiling in each room where there is a fuel burning appliance. Much like smoke detectors, carbon monoxide detectors can be wired directly into the homes electrical system, plugged into a receptacle and/or battery operated. Also, like smoke detectors, battery operated units should be tested weekly while hard wired systems should be tested monthly. If a CO detector does go off, immediately evacuate everyone from the home and call the fire department, open doors and windows to ventilate the house. Remember that because carbon monoxide is colorless and odorless, never ignore an alarm even if you feel no adverse symptoms. More information can be found in the CMHC document at http://www.strandhi.com/library/cmhc_co_62046.pdf.
From the United States EPA (Environmental Protection Agency): Carbon Monoxide Detectors are widely available in stores and you may want to consider buying one as a back-up, BUT NOT AS A REPLACEMENT for proper use and maintenance of your fuel-burning appliances. However, it is important for you to know that the technology of CO detectors is still developing, that there are several types on the market, and that they are not generally considered to be as reliable as the smoke detectors found in homes today. Some CO detectors have been laboratory-tested, and their performance varied. Some performed well, others failed to alarm even at very high CO levels, and still others alarmed even at very low levels that did not pose any immediate health risk. Unlike a smoke detector, where you can easily confirm the cause of the alarm, CO is invisible and odorless, so its harder to tell if an alarm is false or a real emergency. Don’t let buying a CO detector lull you into a false sense of security. Preventing CO from becoming a problem in your home is better than relying on an alarm.