Carbon monoxide poisoning

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About carbon monoxide

Carbon monoxide (also known as CO) is a gas that causes illness and can lead to death. It has no:

  • smell
  • taste
  • colour

Carbon monoxide is produced whenever you burn fuel like:

  • coal
  • gasoline
  • natural gas
  • oil
  • propane
  • wood or wood pellets

It's also a product of second-hand smoke.

Carbon monoxide is lighter than air and can move freely throughout your home or cottage at any time of the year. However, the risk is greatest in winter months because most homes in Canada are heated by:

  • furnaces
  • wood stoves or wood pellets
  • water heaters or boilers
  • other appliances that run on burning fuels

These devices can release carbon monoxide into your home if they are not installed or maintained correctly, or if they malfunction.

Other sources of carbon monoxide include:

  • gas-powered generators
  • charcoal grills
  • vehicle exhaust
  • gas-powered cooking appliances
  • blocked chimney flues
  • gas-powered dryers

These devices become a risk when they are used in unventilated or poorly ventilated areas, such as a:

  • home
  • garage
  • cottage
  • camper
  • tent

Symptoms of carbon monoxide poisoning

Breathing CO reduces your body's ability to carry oxygen in your blood and can affect you before you notice its presence. Exposure to the gas can cause carbon monoxide poisoning (CO poisoning) and is dangerous to your health.

At low levels, CO poisoning effects include flu-like symptoms, such as:

  • tiredness
  • headaches
  • shortness of breath
  • impaired motor functions, such as:
    • muscle weakness
    • partial or total loss of function of a body part (limb or limbs)

At increased levels, or if you are exposed to low levels for longer periods of time, you can experience:

  • dizziness
  • chest pain
  • poor vision
  • difficulty thinking

At very high levels, it can cause:

  • convulsions
  • loss of consciousness
  • coma
  • death

Preventing carbon monoxide poisoning

Keep your home and cottage air clean and free of carbon monoxide by:

  • avoid smoking indoors
  • keeping the door between your house and the garage closed
  • not idling vehicles in the garage, even when the garage door is open

Never use:

  • Never use gas-powered machines in the garage, such as:
    • trimmers
    • generators
    • lawnmowers
    • snowblowers
  • Never use a barbecue or portable fuel-burning camping equipment inside a:
    • home
    • garage
    • vehicle
    • camper
    • tent
  • Never use kerosene or oil space heaters and lamps in enclosed areas unless they're specifically designed for indoor use

Regular appliance maintenance and inspections

You can help prevent carbon monoxide release into the home with good maintenance of fuel-burning appliances.

Make sure appliances are regularly maintained and inspected by a professional at least once a year or in accordance with the manufacturer's instructions. This includes fuel-burning:

  • furnaces
  • fireplaces
  • stoves
  • water heaters
  • dryers

Home owners should regularly examine propane and natural gas powered appliances, such as:

  • stoves
  • dryers
  • heaters
  • refrigerators

They should be checking for:

  • leaks
  • cracks
  • blocked vents
  • improper installations
  • poor connections of gas lines to:
    • appliances
    • vents
  • breaks or tears in connection tubes
  • corroded or disconnected venting pipes

Inspect exhaust vents during and after snowstorms to make sure they are not blocked with ice or covered by snow or debris. Do this for your:

  • dryer
  • furnace
  • fireplace and chimney
  • heat recovery ventilator (HRV)
  • wood-burning or gas stove

Carbon monoxide alarms

Carbon monoxide (CO) can only be detected with a carbon monoxide alarm. You should have at least one CO alarm installed in your home, in addition to a smoke alarm. Smoke alarms alert you to fires, not carbon monoxide. CO alarms can be purchased at any hardware or home equipment store.

Certification marks

When buying CO alarms at stores or online, it is important to look for products that are certified for use in Canada.

The certification marks must be to Canadian safety standards.

CO alarms with a Canadian certification mark have been tested by laboratory professionals. The mark indicates that the product meets the requirements of Canadian safety standards.

Certification marks must be found on:
  • the CO alarm, and
  • the product packaging.

Here are some common Canadian certification marks you may find on CO alarms and their packaging:


For products sold online, the product description may also indicate if the CO alarm is certified to Canadian safety standards. If you are not sure, ask the seller. If the seller cannot confirm that the product is certified to Canadian safety standards and bears a Canadian certification mark, don't take the risk, only purchase products that have this required information.

Find out more about buying consumer products online.

Install carbon monoxide alarms correctly

The most important place to install a CO alarm is in hallways, outside of sleeping areas. It will have an audible alarm to warn you of high carbon monoxide levels in your home.

Make sure to follow the manufacturer's suggestions for:

  • installation
  • testing
  • use
  • maintenance
  • replacement

Test carbon monoxide alarms regularly

Test your CO alarms regularly. Replace batteries and the CO alarm as recommended by the manufacturer. Write on the battery or device to remind yourself when it was installed and when it should be replaced. Check the expiry date of your CO alarms and replace them when necessary.

Contact your local fire department for more information on the use and installation of carbon monoxide alarms in your area.

If your carbon monoxide alarm sounds

If your carbon monoxide alarm sounds, you should do the following.

  1. leave your home immediately and move to fresh air
  2. do not try to locate the source of carbon monoxide
  3. once outside, call 9-1-1, your local fire department, or emergency services
  4. return to your home only after the problem has been fixed by a professional

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