Carbon Monoxide

What is it?

Carbon monoxide is a flammable, colourless, odourless, tasteless toxic gas produced during incomplete combustion of fuel - natural gas, oil, coal, wood etc.

During normal combustion, each atom of carbon in the burning fuel joins with two atoms of oxygen - forming a harmless gas called carbon dioxide. When there is a lack of oxygen to ensure complete combustion of the fuel, each atom of carbon links up with only one atom of oxygen - forming carbon monoxide gas.

What is the danger to me?

Carbon monoxide inhibits the blood’s capacity to carry oxygen and in our lungs, quickly passes into the bloodstream and attaches itself to haemoglobin (oxygen carrying pigment in red blood cells). Haemoglobin readily accepts carbon monoxide - even over the life-giving oxygen atoms (as much as 200 times as readily as oxygen) forming a toxic compound known as carboxyhaemoglobin (COHb).

By replacing oxygen with carbon monoxide in our blood, our bodies poison themselves by cutting off the needed oxygen to our organs and cells, causing various amounts of damage - depending on exposure.

Low levels of carbon monoxide poisoning (with COHb levels of 10%) result in symptoms commonly mistaken for common flu and cold symptoms - shortness of breath on mild exertion, mild headaches, nausea.

With higher levels of poisoning (COHb levels of 30%) the symptoms become more severe - dizziness, mental confusion, severe headaches, nausea, fainting on mild exertion.

At high levels (CHOb of 50% or more) there may be unconsciousness and death.

How does CO enter the home?

Carbon monoxide can escape from any fuel-burning appliance, boiler, water heater, fireplace, woodstove, or space heater.

Most new homes are built very air-tight, thus cutting down on the supply of fresh air to your furnace - and creating an oxygen-starved flame. Tight closing replacement windows and doors, as well as additional insulation can cause similar problems in older homes.

Carbon monoxide can spill from vent connections in poorly maintained or blocked chimneys. If the flue liner is cracked or deteriorated, CO can seep through the liner and into the house - slowly creeping up to dangerous levels. If a nest or other materials restrict or block the flue, CO will mostly spill back into the house.

Improperly sized flues connected to new high-efficiency boilers and water heaters can also contribute to CO spillage. (Many new boilers and water heaters are installed using the existing chimneys which may be the wrong size to allow the boiler to vent properly.)

Warming up vehicles in an attached garage, even with the garage door opened, can allow concentrated amounts of CO to enter your home through the car port door or near-by windows.

What can I do to ensure my family's safety?

Have your chimney swept at least once every year, ideally before each winter. Always use a recommended chimney sweep, preferably a member of the National Association of Chimney Sweeps, an association of true professionals in the field. Check in Yellow Pages for a list of members in your area.

Have your heating appliances serviced regularly by a member of HETAS.

What to do in a CO emergency

If you are suffering from chronic flu-like symptoms, see your doctor and ask him if it could be caused by low-level CO poisoning.

If you have a CO detector, and it alarms, open windows and ventilate your home with fresh air and have your heating system checked by a professional.

If your alarm sounds and you are feeling drowsy or dizzy, leave the house and call 999 from your neighbour’s home. You may need medical attention for CO poisoning.