MADISON, WI — With the onset of cooler temperatures, people across the country are winterizing their homes — sealing windows and servicing their furnace. Aprilaire notes that they should also be testing and, if necessary, replacing their carbon monoxide (CO) alarms.

Carbon monoxide poisoning is the number one cause of unintentional poisoning deaths in the world, says the company. There are many sources of CO, and it is not a concern that is exclusive to the winter months. Carbon monoxide poisonings and fatalities happen year-around.

Carbon monoxide is a highly poisonous gas, which is released when fuels are burned. Sources of CO can include:

  • Furnaces;

  • Kerosene and gas space heaters;

  • Wood stoves;

  • Gas Stoves;

  • Fireplaces;

  • Generators;

  • Water heaters;

  • Grills;

  • Automobile exhaust;

  • Boat exhaust; and

  • Tobacco smoke.

    Dangerous levels of CO can occur if one or more of the following conditions exist: an appliance is faulty or is poorly maintained, an exhaust flue is partially or totally blocked, or if a room is not adequately ventilated.

    Carbon monoxide is invisible, has no smell, and is therefore impossible to detect with the human senses. The following symptoms are related to CO poisoning:

  • Mild exposure: Slight headache, nausea, vomiting, fatigue (often described as "flu-like" symptoms).

  • Medium exposure: Severe throbbing headache, drowsiness, confusion, fast heart rate.

  • Extreme exposure: Unconsciousness, convulsions, cardiorespiratory failure, death.

    Young children, the elderly, and pets may be the first to experience the above symptoms.

    According to the National Safety Council, the following can be done to prevent CO poisoning:

  • Ensure that appliances are properly adjusted and working to manufacturers' instructions and local building codes.

  • Obtain annual inspections for heating systems, chimneys, and flues and have them cleaned by a qualified technician.

  • Open flues when fireplaces are in use.

  • Use proper fuel in kerosene space heaters.

  • Do not use ovens and gas ranges to heat a home.

  • Do not burn charcoal inside a home, cabin, recreational vehicle, or camper.

  • Make sure stoves and heaters are vented to the outside and that exhaust systems do not leak.

  • Do not use unvented gas or kerosene space heaters in enclosed spaces.

  • Never leave a car or lawn mower engine running in a shed or garage, or any enclosed space.

  • Make sure a furnace has adequate intake of outside air.

    Aprilaire, a manufacturer of carbon monoxide alarms, also suggests installing a CO alarm that meets new U.L. standards on each level of the home.

    For more information, visit the Aprilaire website at

    Publication date: 10/21/2002