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Carbon monoxide (CO) is a poisonous gas that is undetectable to humans. It is a colourless odourless auto-asphyxiant that attaches itself to your blood cells so that the blood cell cannot deliver oxygen throughout your body. High concentrations of CO in your blood will disrupt all oxygen flow, causing death by asphyxiations (even though you are breathing). Carbon monoxide is created when a fuel-burning device does not burn the fuel efficiently. Outdoor appliances such as barbeques, lawnmowers, and cars are not designed to be operated indoors because they are regular producers of CO. Even indoor devices such as furnaces, gas stoves, or fireplaces can produce large quantities of CO if they are not maintained properly, get excessively dirty, or malfunction.


The only way to detect carbon monoxide is with a working carbon monoxide alarm that has been installed correctly. CO alarms come in different styles and with many features, but all of them will protect your family from “the silent killer”.


Plug-In: The most common style of carbon monoxide alarm is the plug-in style (with or without battery back-up). These alarms are only beneficial if you have an electrical outlet in the area where the alarm is required.

Battery-Operated: Battery-operated alarms are more versatile than plug-in alarms because they can be installed anywhere – no electricity required. If you frequently need that outlet and constantly find yourself unplugging the CO alarm then this is the alarm for you. The downside, of course, is that the batteries must be changed regularly.

Combination Alarms: A combo smoke/CO alarm provides the best of both alarms in the same device. These alarms are ideal for those with children or pets who can play with the plug-in alarm, or those who don’t have a lot of space in the hallway where the alarm is required.

Multi-Gas: Some alarms are able to detect natural gas and/or liquid propane as well as carbon monoxide. These alarms offer added protection for homes that use these gases.


Display: Some alarms can relay information to the user through a display. The highest level of carbon monoxide recorded (peak level) or even a low battery (lb) indication is common with a display.

Peak Level: When the peak level button is pressed the unit will display the highest level of carbon monoxide it has recorded in the last month or since it was last energized. This information is great for diagnosing a suspected issue, but only if you read and understand the alarm’s instructions.


Most carbon monoxide alarms do not have an expiry date indicated on them. That’s because the expiry timer starts when it is powered for the first time. Check the packaging to determine if your alarm expires after 5, 7, or 10 years, and make sure you write in the expiry date when you install the new alarm.


Unlike most smoke alarms, CO alarms are sophisticated machines that have several warning tones built into them. Depending on the model/features of the alarm, it could beep or chirp for a low battery, indication that it has lost power, indication that it has lost power and is using the back-up battery, indication of device fault, or indicating it’s end-of-life. None of these tones are an emergency – learn what the various tones mean in the manufacturer instructions.

An emergency tone for a CO alarm is 4 beeps and a pause. This sound can be heard on any CO alarm simply by pressing the test button. If you hear this sound, vacate the home and call 911 from a safe location.