With two young children, I try to make my home as safe as possible. However, I worry about the possibility of carbon-monoxide poisoning, since I know we can't see or smell this gas. What causes it? What are the symptoms? How can I prevent it? -- Gasping for Air

Dear Gasping:

Carbon monoxide is generated by the incomplete combustion of fuels, such as natural gas, wood, oil, propane, and even charcoal. Each year, some 200 Canadians are killed by this gas, and more than 1,500 others are exposed to levels so dangerous that they need medical attention. Because it is colourless, odourless, and tasteless, it is called "the silent killer." You don't know it's there until you become ill -- or worse.

Those grim facts won't help you breathe any easier, but a carbon-monoxide detector should. Install it near the sleeping area, but not on the ceiling and not near fuel-burning appliances.

But prevention is still the best cure, so take the following measures to keep this deadly gas at bay:

• Have your furnace, wood stove, fireplace checked regularly and serviced by a qualified professional.
• Ensure that there is an adequate supply of fresh air coming into your home for the proper operation of these appliances.
• Never use your barbecue -- propane or charcoal -- in an enclosed area, such as your garage.
• Don't leave your car running in an attached garage.
• Don't operate your gasoline-powered lawn mower, snow blower, chain saw, etc., in your workshop or garage.

One of the danger signs that a gas burner is out of adjustment, according to the Canada Safety Council, is a flickering yellow flame, rather than a blue, steady flame. So if you see yellow, call for service right away.

Symptoms of carbon-monoxide poisoning in low concentrations include shortage of breath on moderate exertion and a slight headache. At higher concentrations, victims experience severe headache, mental confusion and dizziness, impairment of vision and hearing, and fainting on exertion. Extreme concentrations lead to unconsciousness and, ultimately, death.

At the first signs of any of these symptoms, move the victim immediately to fresh air and call for emergency assistance. If you need to remove an unconscious victim to the outdoors, open the doors and windows first for maximum ventilation. The patient should be kept lying down and warm until the ambulance arrives. Under no circumstances should he or she be allowed to walk for at least two hours after regaining consciousness. If breathing stops, apply artificial respiration immediately.

Armed with these safety tips, you shouldn't have to worry about having a bad air day.