Carbon monoxide (CO) is a colorless, odorless gas produced whenever any fuel such as gas, oil, kerosene, wood or charcoal is burned. Low levels of CO can cause nausea, headaches, weakness and muscle aches; higher doses can impair judgment, cause paralysis or coma, and in severe cases, death.

To prevent carbon monoxide poisoning, have your fuel-burning appliances inspected and serviced yearly by a trained professional. These inspections can identify cracked or rusted heat exchangers or blocked chimneys before they let carbon monoxide build up in the house. Make sure the furnace or boiler, gas stove or dryer, wood stove or fireplace are vented to the outside. Never use unvented combustion appliances indoors. Also, never allow a car to idle in a garage even when the door is open. Don't burn charcoal inside a home or any enclosed space. Open flues when using a fireplace.

Low levels of CO can cause shortness of breath, mild nausea and mild headaches. Moderate levels cause severe headaches, mental confusion, nausea and fainting. High levels can be fatal.

If you experience any of these symptoms, get fresh air immediately—open doors and windows, turn off combustion appliances and leave the home. Go to the emergency room and inform medical personnel that CO poisoning is suspected and ask for a CO blood test.