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Carbon monoxide (CO) is an odourless, colorless, tasteless toxic gas that enters the body through the lungs during the normal breathing process. It comes from sources such as vehicle exhaust, woodstoves, or propane and gasoline fired equipment that is not functioning properly or appropriately ventilated. Low levels over long periods of time are dangerous, and high levels can cause unconsciousness and even death. To keep your indoor air clean and healthy, be sure that fuel-burning devices are well ventilated, maintained and inspected frequently.

Use a carbon monoxide detector in your home

Unsafe levels of CO can be detected by carbon monoxide detectors, which are constructed to detect airborne concentration levels of CO in parts per million (ppm) and sound an audible alarm when harmful levels are present. Ontario's fire code requires detectors near all sleeping areas in homes with fuel-burning appliances such as furnaces, stoves or fireplaces and all residences with attached garages.

If your CO Detector alarm sounds:

  • Ensure all people and pets leave the building
  • Call 911
  • Seek medical attention if symptoms are present
  • Once everyone is safe call EPCOR at (519) 773-5321 or
  • Call a heating contractor registered with TSSA for an inspection; there could be a charge for this service.

Prevent carbon monoxide in your home

Natural gas has a safety record that’s second to none and there are strict codes that govern the installation and operation of natural gas equipment and appliances. While well-maintained equipment can operate safely for many years, wear and malfunctions can increase the risk of CO entering your home. You can reduce this risk:

  • Have your fuel-burning equipment inspected annually by a TSSA registered heating contractor to identify and fix any potential problems that could prevent your equipment from operating safely. Have the contractor check your natural gas fireplace during the same service call. Find a registered contractor by calling the TSSA at 1-877-682-TSSA (8772), or by visiting: TSSA’s Find a Contractor.
  • Ensure your outdoor exhaust outlets for furnaces, fireplaces, water heaters, and clothes dryers are clear of ice, snow, birds’ nests, or other potential obstructions, so that carbon monoxide emitted by these appliances does not spill and build up in your home or business.
  • Install CO alarms on every level of your home to warn you of the presence of CO and regularly check the batteries.
  • Never use outdoor appliances indoors.
  • Check your chimney. If your chimney is plugged, you could breathe the exhaust from a furnace, fireplace, or woodstove. Stay healthy by checking your chimney in the following manner:
    • Examine the exterior brickwork from top to bottom. Make sure that there are no chalky deposits, moisture stains, cracks, or loose mortar.
    • Empty the clean-out pit at the base of your chimney. Check its contents for mortar, brick, birds’ nests, dead birds or stones. (The clean-out pit is located either inside or outside the house. Look for a metal frame with a door (if masonry chimney), or a “Y” or “T” fitting with a clean out cap installed at the chimney connection for the furnace vent (if manufactured metal chimney). The clean-out door and the cap should be kept closed at all times.
  • Check for chimney obstructions by positioning a mirror in the clean-out pit, and moving it to find the angle that will allow you to see daylight clearly. (If you have an offset chimney, call a chimney specialist. If your appliances use a metal vent, the exterior portion of vent above the roof should be properly maintained. A coat of latex paint will protect it from weather and rusting.)
    • If you see any evidence of a deteriorating chimney, contact a qualified chimney contractor for assistance.

Symptoms of carbon monoxide poisoning

If CO is inhaled, it depletes the amount of oxygen in the red blood cells, resulting in specific symptoms. Depending on the amount inhaled and the length of exposure, symptoms may include the following:

  • Headache, dizziness, nausea, vomiting, mental confusion, weakness, burning eyes, fainting, confusion, drowsiness.
  • Often mistaken for common ailments like the flu.
  • Symptoms improve when away from the home for a period of time.
  • Symptoms are experienced by more than one member of the household.
  • The elderly, children and people with heart or respiratory conditions may be particularly sensitive to carbon monoxide.
  • Continued exposure to higher levels may result in unconsciousness, brain damage and even death.

Signs that carbon monoxide may be present in your home

Other than the audible alarm of your CO detector, there are other signs:

  • Stuffy, stale or smelly air (e.g., the smell of something over-heating or burning).
  • Dripping water condensation on your windows. (This is a reliable sign if you’ve already taken steps to reduce moisture production in your home. It could also mean your humidifier is set too high.)
  • Back draft or soot from a fireplace, chimney or other fuel burning equipment.
  • A yellow burner flame, instead of the normal clear blue flame. This does not apply to natural gas fireplaces in which the yellow flame is intentional for a pleasing appearance.
  • A pilot light that keeps going out or the smell of gases in your home. Even though carbon monoxide is odourless, it is sometimes accompanied by odour-bearing exhaust gases.

If you detect these signs, consider whether you need to call 911 and obtain medical assistance. At minimum, turn off the equipment and contact a TSSA registered heating contractor.

Learn more about carbon monoxide by visiting