Carbon monoxide safety

Changes to the Ontario Fire Code

Changes to the Ontario Fire Code related to carbon monoxide are coming into effect on January 1, 2026. Learn more about how these impact requirements for carbon monoxide alarms.

Overview

Carbon monoxide (CO) is known as the silent killer because it is an invisible, tasteless and odourless gas that can be deadly. Over 65% of CO-related injuries and deaths in Ontario occur in the home.

CO is produced when fuels — such as propane, gasoline, natural gas, heating oil or wood — do not burn completely in fuel-burning appliances and devices, such as:

• furnaces
• gas or wood fireplaces
• hot water heaters
• stoves
• barbeques
• portable fuel-burning heaters
• generators
• vehicles

Exposure to CO can cause:

• headaches
• nausea
• dizziness
• confusion
• drowsiness
• loss of consciousness
• death

If your CO alarm sounds, you or other occupants may experience symptoms of CO poisoning. It is critical to get everyone out of the home immediately and call 9-1-1 or your local emergency services number from outside the building.

How to prevent carbon monoxide build-up in your home

The following tips can help prevent carbon monoxide build-up in your home:

• Ensure fuel-burning appliances, chimneys and vents are cleaned and inspected by professionals every year before cold weather sets in. Find a registered contractor near you.
• Ensure outside vents and chimneys for the dryer, furnace, stove, fireplace and other fuel-burning appliances are always clear of snow and debris.
• Only use gas and charcoal barbeques outside, away from all doors, windows, vents and other building openings. Never use barbeques inside garages, even if the garage door is open.
• Only use portable fuel-burning generators outdoors in well-ventilated areas away from windows, doors, vents and other building openings.
• Ensure all portable fuel-burning heaters are vented properly, according to the manufacturer’s instructions.
• Never use a stove or oven to heat your home.
• Open the flue before using a fireplace for adequate ventilation.
• Never run a vehicle, fueled engine or motor inside a garage, even if the garage door is open. Always remove a vehicle from inside the garage immediately after starting it.

When and where to install carbon monoxide alarms

Carbon monoxide can only be detected by a working CO alarm — learn the law and how updates to the fire code apply to all existing homes.

Install in a house

If you live in a house, a CO alarm must be installed if the home:

• has a fuel-burning appliance
• has a fireplace
• has an attached garage
• is heated by air from a fuel-burning appliance that is not contained within your home (in effect on January 1, 2026)

Where to install

A CO alarm must be installed in each of the following locations in a house:

• adjacent to each sleeping area (this means the hallway or area outside the sleeping area, for example, a carbon monoxide alarm must be installed in the hallway nearest multiple bedrooms in a house or apartment)
• on every storey of your home, including storeys that do not have sleeping areas (in effect on January 1, 2026)

Install in an apartment or condo unit

If you live in an apartment or condo unit, a CO alarm must be installed if any of the following applies:

• your unit has a fuel-burning appliance or a fireplace
• the building has a service room, and your unit is located directly above, below, or beside the service room
• the building has a garage, and your unit is located directly above, below or beside the garage
• your unit is heated by air from a fuel-burning appliance that is not contained within your unit, for example, heated air coming from a furnace in a building service room (in effect on January 1, 2026)

Where to install

A carbon monoxide alarm must be installed in each of the following locations in an apartment or condo unit:

• adjacent to each sleeping area of your unit (this means the hallway or area outside the sleeping area, for example, a carbon monoxide alarm must be installed in the hallway nearest multiple bedrooms in a house or apartment)
• on every storey of your unit, including storeys that do not have sleeping areas (in effect on January 1, 2026)
• in public corridors of the building if the corridors are heated by air from a fuel-burning appliance (in effect on January 1, 2026)

Responsibilities

Building owners

Building owners are responsible for complying with carbon monoxide alarm requirements under the Fire Code.

Landlords

In rental suites, landlords are responsible for:

• installing and maintaining carbon monoxide alarms in their rental units
• testing carbon monoxide alarms in rental units annually, when the battery is replaced, when changes are made to the electrical circuit, or a change of tenancy occurs.
• providing the tenant with a copy of the carbon monoxide alarm’s maintenance instructions

Tenants

Tenants are responsible for notifying the landlord if they are aware of any issue with a carbon monoxide alarm in their unit. 

It is against the law for anyone to remove the batteries or tamper with carbon monoxide alarms in any way.

Requirements for carbon monoxide alarms

Carbon Monoxide alarms should be installed according to the manufacturer’s instructions. Under the Fire Code, carbon monoxide alarms are permitted to be either:

• hardwired
• battery-operated
• plug-in devices

Many devices on the market are combined units that include both a smoke alarm and carbon monoxide alarm in one device.

Your CO alarm sounds or alerts differently than your smoke alarm, make sure everyone in your home knows the difference.

Canadian performance standards

When purchasing carbon monoxide alarms or combined units, make sure they meet Canadian performance standards by checking if they have the logo of a recognized standards testing agency, such as:

Maintenance

You must maintain your carbon monoxide alarm in operating condition and should:

• test carbon monoxide alarms every month by pressing the test button
• replace batteries every year
• replace carbon monoxide alarms according to the manufacturer's instructions

If your CO alarm is chirping, check to see if the battery needs replacing or the alarm has reached its "end-of-life". Consult the CO alarm manufacturer’s instructions and know the difference between the CO alarm’s low-battery warning, end-of-life warning and an emergency alarm.

Questions

For questions regarding carbon monoxide alarm requirements that may apply to your specific home or building, please contact your local fire department.

Public education resources

• To request public education resources, please contact the Office of the Fire Marshal's Public Education and Communications unit by emailing OFM.PubEd@ontario.ca.