California Agency Issues Seasonal Warning: Health Threats Related To Carbon Monoxide

This month, the California Air Resources Board (ARB) issued its seasonal carbon monoxide (CO) warning to state residents, especially the elderly, pregnant women and people with heart and respiratory ailments.

"Carbon monoxide poisoning is a serious health threat during the winter months," said Catherine Witherspoon, ARB executive officer. "Basic safety inspections of your appliances for leaks or damage can prevent a tragic accident from occurring."

Each winter, tragic accidents occur when people are exposed to toxic levels of indoor carbon monoxide from improperly vented or leaking furnaces, ovens and fireplaces. On average each year, 30 to 40 Californians die and many more experience flu-like symptoms from accidental CO poisoning. These tragedies are easily preventable. Burning fuel produces carbon monoxide, and extended exposure to the compound can have a lethal effect on humans. Even below toxic levels, exposure to CO may cause headaches, nausea, fatigue or heart pain.

Carbon monoxide adheres to red blood cells, blocking their ability to carry oxygen and thereby depriving the body's heart and brain of an adequate supply. The deprivation of oxygen leaves a person feeling sleepy and tired. If the person is not removed from the area and treated, unconsciousness and death may result.

Because of concern over increased natural gas rates, many people are purchasing kerosene or propane space heaters this winter, or buying wood for use in long-ignored fireplaces and woodstoves. However, unvented combustion devices such as kerosene or propane space heaters cannot be sold for residential use in California because of carbon monoxide hazard, officials said. Fireplaces and woodstoves that have not been used or inspected pose a similar risk, because of the potential for blocked flues, leakage, backdraft and other factors.

More than half of CO poisoning deaths in California are from malfunctioning or improperly vented combustion appliances. Proper use and maintenance of any appliances that produce a flame such as gas furnaces, gas and propane space heaters and barbecues, can prevent exposure to lethal levels of CO. Because of the danger from poor ventilation, California law prevents the use of kerosene or propane space heaters, charcoal grills and unvented gas logs indoors. Also, officials said gas stoves and ovens should not be used for heating the home. All of these combustion appliances also can emit large amounts of nitrogen dioxide, which can cause respiratory disease, especially in children.

In addition, the ARB advises caution when operating 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, many due to running them in closed garages.

The ARB encourages annual check-ups of gas appliances 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, and this type of detector is recommended for homes with young children or elderly or sick occupants.

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 appliances, contact your local utility provider, state weatherization contractor, or utility-certified heating contractor immediately and request a Combustion Appliance Safety Test.

ARB data show that outdoor carbon monoxide levels rise throughout California between the months of November and March because of stagnant weather conditions. These outdoor levels of CO have been measured in covered garages and at busy intersections. Rising levels of outdoor CO may generate health complaints in sensitive people. Cars should be tuned and muffler systems checked regularly for exhaust leaks.

Free booklets, "Combustion Pollutants in Your Home" ( and "Woodburning Handbook" ( -- PDF format) are 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.

Additional information on CO and indoor air quality can be found at EPA's Web site:

This article originally appeared in the 10/01/2006 issue of Environmental Protection.

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