Carbon monoxide (CO) is a poisonous gas that has no colour or smell. Fuel-burning appliances can release it, and a working carbon monoxide alarm is essential for detecting it. See Health Canada’s alarm guidance.
Exposure can cause headaches, nausea, dizziness, confusion and drowsiness. Serious exposure can lead to loss of consciousness or death. The effects depend on both the concentration and the length of exposure; a household should not rely on a particular concentration as a safe threshold.
If your carbon monoxide alarm sounds, get everyone outside immediately. Call 9-1-1 or your local emergency services from outside. Do not stay inside to inspect an appliance or look for the source, and do not return until professionals say it is safe.
Use a carbon monoxide alarm certified for use in Canada and follow its installation, testing and replacement instructions. Have fuel-burning appliances, chimneys and vents inspected and maintained by qualified professionals.
For current guidance, see Ontario carbon monoxide safety and Health Canada’s carbon monoxide prevention advice.