Release 03-25      

October 30, 2003


Jerry Martin
Dimitri Stanich
(916) 322-2990
Carbon Monoxide: A Winter Months' Health Threat

SACRAMENTO -- The California Air Resources Board (ARB) today announced its annual winter months’ carbon monoxide warning. On average each year, 45 Californians die and many more experience flu-like symptoms from accidental carbon monoxide (CO) poisoning. These are easily preventable tragedies.

“Carbon monoxide is an insidious poison.  It’s a colorless, odorless gas that lulls a person to complacency,” said Dr. Alan Lloyd, Chairman of ARB. “It aggressively removes the capacity of blood to transport oxygen, making the person tired and sleepy. If the person is not removed and treated quickly suffocation ensues. An otherwise perfectly healthy person can die in very little time.”

Each winter, tragic accidents occur when people are exposed to lethal levels of indoor CO from improperly vented or leaking furnaces, ovens and fireplaces. Even at below-lethal levels, exposure to CO may cause headaches, nausea, fatigue or heart pain.  

CO is produced by burning fuel and has toxic effects in humans. It adheres to red blood cells blocking their ability to carry oxygen and thereby deprives the body’s sensitive organs, the heart and brain, of an adequate supply. Extended exposure to high levels of CO can result in permanent damage and death. Those most susceptible include infants, young children, fetuses, the elderly and patients with heart or respiratory diseases.

CO poisoning can be prevented by proper use, maintenance and venting of any appliances that produce a flame. More than half of CO poisoning deaths are from malfunctioning or improperly vented combustion appliances such as gas furnaces, gas and propane space heaters and small barbecues. Gas ovens should not be used for heating the home. Because of the danger from poor ventilation, kerosene or propane space heaters, charcoal grills and unvented gas logs cannot be used legally indoors in California.

Care should also be taken not to operate cars or other internal combustion engines in enclosed spaces or attached garages. A third of CO poisoning deaths are the result of accidental exposure from vehicles running in closed garages.

People who heat with propane appliances, older wall or floor gas furnaces and fireplaces should be especially careful.  Fireplaces and wood stoves should be checked for damage and cleaned each year before use. If you are concerned about the safety of your gas furnace or oven, contact your local utility provider or utility-certified heating contractor immediately and request a Combustion Appliance Safety Test. Some utility companies will inspect home equipment for little or no charge.

The ARB also encourages annual furnace check-ups by a qualified professional and the use of Underwriters Laboratory (UL) approved CO detectors that sound an alarm when dangerous carbon monoxide levels are detected. Some detectors also have warning signals or digital readouts to indicate lower levels of CO.

ARB data show that outdoor CO levels rise throughout California between November and March because of stagnant weather conditions. Outdoor levels of CO high enough to trigger health complaints in sensitive people have been measured in covered garages and at busy intersections. Cars should be tuned and muffler systems checked regularly for exhaust leaks.

Free booklets, "Combustion Pollutants in Your Home” and “Woodburning Handbook” (1.4 MB PDF) is available from ARB by calling (916) 322-8282 or by writing to: Air Resources Board, Indoor Air Quality Program, Research Division, P.O. Box 2815, Sacramento, CA 95812.

The Air Resources Board is a department of the California Environmental Protection Agency. ARB's mission is to promote and protect public health, welfare, and ecological resources through effective reduction of air pollutants while recognizing and considering effects on the economy. The ARB oversees all air pollution control efforts in California to attain and maintain health based air quality standards.

The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of simple ways you can reduce demand and cut your energy cost, see our website at

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