NORTHBROOK, IL -- Carbon monoxide (CO) is a silent killer that can stalk any home with fuel-burning appliances. Within minutes, high concentrations of this odorless, colorless and invisible gas can become lethal.

Each year in the United States more than 500 people die in their homes from unintentional CO poisoning and 10,000 people are treated in hospital emergency rooms for poisoning symptoms.

``Dangerous levels of CO can build up in an apartment, condominium or house that has fuel-burning appliances,'' says John Drengenberg, manager of Consumer Affairs for Underwriters Laboratories Inc. (UL), the not-for-profit product safety testing organization. ``If not maintained or used properly, fire places, gas or kerosene space heaters, oil and gas furnaces, and gas-burning appliances such as water heaters, ranges, and clothes dryers can generate CO.''

Drengenberg explains that CO is a by-product of malfunctioning appliances that don't completely burn their fuel. When these appliances aren't adequately ventilated, the CO poisoning symptoms can occur. Theses symptoms resemble the flu: nausea, fatigue, headaches, dizziness, breathing difficulty and confusion. Untreated, CO poisoning can cause death.

``Detection is the best way to prevent CO poisoning,'' he says. ``A CO alarm detects elevated levels of the gas and warns you and your family of a potential poisoning risk. If you have any fuel-burning appliances in your home, your family's safety demands that you have CO detectors.''

During October, National Fire Safety Month, UL also recommends you consider these CO preventive measures:

• Have a qualified technician inspect your fuel-burning appliances and chimneys to ensure they operate correctly and that nothing blocks the vapors from being vented out of the house.
• Install a UL-Listed CO alarm according to the manufacturer's instructions and at least 10 feet away from fuel-burning appliances and outside of sleeping areas.
• Test your CO alarm at least once a month and replace the battery at least once a year.
• Make sure all family members know the difference between the sound of the CO alarm and the smoke alarm.
• Never ignore a CO alarm. If your CO alarm sounds, immediately operate the reset/silence button and call your fire department or 9-1-1.
• Move to fresh air, either outside or to an open window or door. Account for every household member.
• Don't re-enter your home or move away from the open door or window until the emergency services have arrived, the home is sufficiently aired out and the CO alarm doesn't reactivate.
• If your CO alarm reactivates within a 24-hour period, repeat the steps above and call a qualified technician to examine your appliances and make any appropriate repairs.