Dec. 18, 2003

COLLEGE STATION - Like a monster in a horror film, this silent and invisible killer can strike down whole families while they sleep.

But unlike movie killers, this one is all too real. And it doesn't wait for darkness. Carbon monoxide, a colorless, odorless gas, kills nearly 300 people in the United States every year, according to statistics from the American Lung Association.

Janie Harris, Texas Cooperative Extension housing and environment specialist, said carbon monoxide is the most dangerous form of indoor pollution because it can kill -- and kill quickly.

Carbon monoxide is produced when gas-, coal- or wood-burning appliances aren't working efficiently and/or aren't exhausted properly, Harris said, which means exposure to the gas is particularly dangerous during the colder months when home heaters are turned on and fireplaces are fired up. Electric appliances, which don't burn fuel, do not produce carbon monoxide, Harris said.

Sources of carbon monoxide in the home include fuel-burning appliances such as boilers, furnaces, water heaters, ovens, stoves and dryers, wood-burning fireplaces and stoves; space heaters fueled by gas or kerosene; gas or charcoal grills; small gasoline or propane engines such as lawn mowers or electric generators; large gasoline-powered engines including automobiles, recreational vehicles and boats; tobacco smoke; and house fires, as well as chimneys and flues that have become blocked.

But Harris said the two main sources of carbon monoxide inside the home are the gas furnace heat exchanger and gas hot water heater. And that's why, she said, annual professional checkups for a home heating systems are so important. "Your central heating system could have a cracked heat exchanger, so you need a professional to come out and service the system every year."

According to the Consumer Product Safety Commission, symptoms of carbon monoxide poisoning mimic the flu, but without the fever, including headache, fatigue, dizziness, nausea and shortness of breath.

This can lead both sufferers and their doctors "to believe they have some kind of germ-caused illness, rather than carbon monoxide poisoning," Harris said.

Headaches or dizziness that seem to improve away from home for an extended period could also indicate carbon monoxide poisoning, Harris said.

The CPSC advises anyone who thinks he or she is experiencing carbon monoxide poisoning to immediately get into fresh air. Open doors and windows to ventilate the house; turn off any fuel-burning appliances and get outside. Go to a neighbor's house and call 911 or the fire department to report the problem and symptoms. See a physician for a qualified diagnosis; be sure to tell the doctor that carbon monoxide poisoning is suspected. And have the fuel-burning appliances checked by a professional before turning them back on.

To help prevent exposure to carbon monoxide in the first place, Harris advised:

- Have furnaces professionally serviced every year. This checkup should include making sure the burner and vent systems are working properly and the heat exchanger has no cracks.

- Inspect the area around the furnace to make sure enough air flow is getting to the burner to bring in fresh air. Furnaces should not be in tightly sealed spaces.

- Inspect the water heater and the furnace flue for internal obstructions or leaks around joints.

- Test a gas water heater while the burner is on by holding a lighted match under the draft hood. I f the match flickers downward or goes out, the exhaust may have a backflow, which means the exhaust is coming into the house instead of outside. The match flame should burn upward toward the flue.

- Make sure dampers on fireplaces and wood stoves are open so all combustion gases -- including carbon monoxide -- flow outside anytime they are in operation.

- Never use a gas oven or stove for heat. "When it starts getting cold, people may turn on the oven and open the (oven) door" to help heat the house, Harris said. This can release carbon monoxide and other harmful combustion gases, such as sulphur dioxide, into the house.

- Don't leave a car, lawn mower or any other gas-powered equipment running inside a closed building, especially an attached garage. Carbon monoxide from the engine could drift back inside the house. In fact, Harris said, leaving a car in an attached garage with the motor running is dangerous -- even if the garage door is open.

- Don't ever set up a charcoal-burning barbecue grill inside a garage either, especially an attached garage. This could allow carbon monoxide to drift into the house.

- When installing or maintaining combustion equipment in the home ** such as heaters, water heaters, fireplaces or gas ovens and stoves -- follow directions and safety precautions carefully.

- Use carbon monoxide alarms on every floor and near sleeping areas. Sleeping people are more vulnerable to carbon monoxide because the concentration level may become deadly while they are sleeping. Choose carbon monoxide alarms that carry the CPSC and Underwriters laboratories' seals of approval. These devices are for sale at hardware stores, discount stores -- nearly any place where smoke detectors can be found, Harris said.

For more information visit the Web at http://fcs.tamu.edu/housing/housing.htm and click on indoor air quality.