When a wood-burning fireplace is in use, the air is continually drawn out of the home and up the fireplace chimney. This air must be replaced to maintain the ideal air-to-gas ratio that allows for complete combustion.

When using fireplaces and wood-burning stoves in your home, it is essential to follow the following precautions to prevent the build-up of CO:

• The fireplace damper must be open when the fireplace is in use. The open damper allows the smoke and gases to exit.
• Install CO alarms on every level of your home.
• Ensure a fresh air supply into your home before lighting the fire.
• Some fireplaces come with their own combustion air duct. If yours is not equipped with this duct, you must have a fresh air supply, such as an open window.
• Keep the fresh air supply available, even overnight, until the fire is completely out.
• Keep the damper closed when the fireplace is not in use.
• Close the damper when the fire is completely out, the ashes are cold or when the fireplace is not in use. This will prevent air and heat loss up the chimney and cold air drafts from coming down the chimney.

Burn dry seasoned wood. Get your wood at least six months before the start of the season to give it a chance to dry out properly. Split, stack, and cover it in spring, so it has time to dry properly. Ensure the moisture content of the wood you burn is less than 20 per cent -- closer to 16 per cent is preferable.

Keep your chimney clean. Have your chimney cleaned regularly by a Wood Energy Technical Transfer (WETT) trained chimney sweep who can also inspect your chimney and wood-burning appliance for other potential problems. Chimney cleaning frequency depends on your wood-burning appliance, the type of wood you burn, how you burn and how much you burn.

Maintain your stove or fireplace. The gasket ensures a tight seal between the door and the stove or fireplace, and should be replaced if there are signs of wear or changes in performance. Check the owner's manual or a stove dealer for information on other parts that may need occasional replacement (e.g. catalytic converters, baffles, insulation, firebrick, etc.).

Load wood properly. Leave a thin layer (1 inch or so) of ash in the bottom of the stove. Fully open any air controls. Start with crumpled newspaper and dry softwood kindling once the kindling has caught, add larger split wood. Load large wood crosswise to encourage airflow around the logs. Aim for a fast, hot burn rather than a slow smouldering burn.

Upgrade your wood burning appliance. New Environmental Protection Agency (EPA) approved appliances burn cleaner (up to 90 per cent less smoke) and more efficiently (use up to one-third less wood). With EPA-approved appliances, it is much easier to burn safely.

• Have your gas fireplace installed by a certified professional.
•  It should be inspected annually by a certified professional or as often as the manufacturer recommends. Not performing regular maintenance may result in inefficient appliance operation, and in some cases, dangerous exposure to carbon monoxide.
• Don’t put flammable materials near your fireplace.
• If the pilot light or flame goes out, follow the manufacturer’s instructions for relighting or have a certified professional come to relight it.
• Never use a fireplace with cracked glass. If your fireplace has cracked glass, have it inspected or replaced by a certified professional.
• Use a screen in front of the fireplace and keep pets and children at least 1 metre away from the hot glass.