"On average, 45 Californians die each year from carbon monoxide (CO) poisoning and many more experience flu-like symptoms from moderate CO exposure. More than half of the deaths are from malfunctioning or improperly vented combustion appliances such as gas and propane heaters and furnaces, and hibachis. One third of the deaths are from accidental exposure to motor vehicle exhaust.

        Carbon monoxide is a colorless, odorless gas that results from burning fuels. Each winter we hear of tragic accidents that occur when people are exposed to lethal levels while using poorly vented or leaking stoves, fireplaces and furnaces for heating. Exposure to lower levels of CO can cause headaches, nausea, or heart pain. Those most susceptible include infants, small children, the elderly and heart and respiratory patients. CO poisoning cases are under-diagnosed and often go unrecognized by the victims and their doctors."

        ARB data shows that carbon monoxide levels rise throughout California between November and March because the compound tends to disperse more slowly in cool temperatures. Levels of carbon monoxide high enough to trigger health complaints in sensitive people have been measured in covered garages and at busy intersections.

        The good news is that carbon monoxide poisoning can be prevented by proper use, maintenance and venting of any appliances that produce a flame. Because of the danger from poor ventilation, kerosene or propane space heaters, charcoal grills and unvented gas logs cannot be legally used indoors in California. Care should also be taken not to operate car engines or other gas-powered equipment in enclosed or attached garages.

        People who heat with fireplaces and older wall or floor gas furnaces should be especially careful. Fireplaces and wood stoves should be checked for damage and cleaned each year before use. Contact your local utility company immediately if you are concerned about the safety of your furnace. The ARB also encourages the use of UL approved carbon monoxide detectors that sound an alarm when dangerous carbon monoxide levels are detected.

        The compound triggers responses in humans by replacing oxygen in red blood cells and depriving heart and brain tissue of enough oxygen to function properly. Extended exposure to high carbon monoxide levels can result in permanent heart or brain damage and even death.

        A free booklet, "Combustion Pollutants in Your Home," 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.