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Perspectives in Disease Prevention and Health Promotion Carbon Monoxide Intoxication -- A Preventable Environmental Health Hazard

Each year in the United States, an estimated 10,000 persons seek medical attention or lose at least one day of normal activity because of carbon monoxide (CO) intoxication; at least 1,500 persons die from accidental exposure to high concentrations of CO; and approximately 2,300 persons commit suicide with CO (1). In addition to acute CO poisoning resulting in death, considerable danger may result from daily exposure to low concentrations of CO in houses, work places, and schools. Prolonged periods of exposure may cause headache, dizziness, and sleepiness. Continued exposure brings on nausea, vomiting, heart palpitations, and, from exposure to high levels of CO for prolonged periods, unconsciousness and death.

Although exhaust from any improperly maintained vehicle can pose serious hazards, the most common source of CO is automobile exhaust or exhaust vented into confined spaces. Because gasoline-powered lawnmowers, charcoal grills, wood stoves, fireplaces, gas space heaters, kerosine or gas powered camp lanterns, heaters, stoves, and similar equipment also produce CO, proper ventilation and prevention of CO build-up in confined areas must be assured (2). In 1980, the Consumer Product Safety Commission estimated 7.6 million unvented gas space heaters were in use; CO from such heaters caused approximately 70 deaths in 1980 (3). Home gas appliances also produce some CO, but under normal, safe-operating conditions, CO occurs in small amounts and should cause no danger when these appliances are properly installed, adjusted, and operated (2).

Numerous studies have demonstrated the seriousness of the CO problem. In 1975, a study to determine usual CO levels during a non-summer month in 80 urban and rural households in Fort Collins, Colorado, showed that 6% of the homes had CO concentrations at or above 10 parts per million (ppm)*, and one had 30 ppm CO in the kitchen and family room. A socioeconomic gradient was found; homes in low socioeconomic areas had the highest CO levels. There was no statistical difference between CO levels in urban and rural housing (4).

In the mid-1970s, the Allegheny County Health Department, Pittsburgh, Pennsylvania, conducted an investigation and found that 58% of the 33 CO fatalities during a 7-year period were located in low socioeconomic areas. In an effort to reduce these fatalities, the county health department conducted a multi-phase CO-reduction program consisting of public education, action (including distribution of CO dosimeters to and inspections of housing units), and evaluations. This prevention program resulted in a zero CO-fatality rate for the first winter in 8 years (5). A 1978 Harvard School of Public Health study of indoor ice skating rinks in the Boston area found that in over 80% of the hours sampled, gasoline-powered ice-resurfacing machines and improper or inadequate venting of exhaust emissions caused levels of CO exceeding the national air-quality standard for exposure (6).

Other studies indicate that CO contamination is not limited to buildings. In 1975, the U.S. Department of Transportation demonstrated that a substantial number of school children and bus drivers may be exposed to harmful levels of CO from school buses. No deaths occurred, but many instances of headache, nausea and non-specific illness were reported (6). In 1976, the New Mexico Environmental Improvement Agency and CDC recognized the potential for CO poisoning from recreational vehicles. CO concentrations of greater than or equal to 35 ppm were discovered in 172 (14.5%) of the 1,187 units tested for appliance-produced CO. Overall CO concentrations of this magnitude due to engine exhaust fumes leaking into the camper were found in 4.4% of 69 units tested. Over 44% of the 994 appliances individually tested emitted CO at concentrations of greater than or equal to 35 ppm. Unvented ovens and stoves, LPG lamps, and gasoline lanterns contributed most to high overall CO concentrations (7) Reported by Program Development Br, Environmental Health Svcs Div, Center for Environmental Health, CDC.

Editorial Note

Editorial Note: CO is a common and lethal gas produced by the incomplete combustion of a solid, liquid, or gaseous fuel and is increased by inadequate air-fuel mixture, insufficient ventilation of combustion gases, and insufficient fresh air intake. It is odorless, colorless, tasteless, and non-irritating, but is often found combined with other gases that may produce a sharp odor and irritate the eyes (1,8). CO is absorbed only through the lungs; toxicity occurs when the gas combines with hemoglobin to form carboxyhemoglobin (COHb). Carbon monoxide-bound hemoglobin is unavailable to transport oxygen. Until CO enters the erythrocytes, it behaves like oxygen. When it contacts the erythrocytes, however, its behavior differs sharply; CO affinity for hemoglobin is approximately 210 times greater than that of oxygen. Death can occur when blood contains from 60% to 80% COHb (1).

The following guidelines summarize the most important techniques for prevention of CO poisoning.

  1. Provide adequate ventilation when using wood stoves and fireplaces, and ensure that all flame-burning appliances are properly installed, adjusted, and operated. Ovens and gas ranges should not be used for heating purposes.

  2. Do not operate gasoline-powered engines (automobiles, lawnmowers, etc.) in confined spaces (such as garages or basements).

  3. Never burn charcoal inside a home, cabin, recreational vehicle, or tent, whether in a grill, hibachi pot, or fireplace, for cooking or heating.

  4. Have only a qualified technician install or convert fuel-burning equipment from one type of fuel to another (2). CO poisoning may increase in coming years because of potential

home-heating fuel shortages, energy costs, extraordinary fuel-conservation measures, and a lack of awareness about the preventability of CO poisoning. Health authorities should implement programs advising the public on the hazards associated with exposure to CO.


  1. Lisella FS, Johnson W, Holt K. Mortality from carbon monoxide in Georgia 1961-1973. J Med Assoc Ga 1978;67:98-100.

  2. Atlanta Gas Light Company. What you should know about carbon monoxide. Atlanta: Atlanta Gas Light Company 1982. (PR 12/80-GP 50M-2).

  3. Consumer Product Safety Commission. Commission proposes new safety standard to reduce deaths from unvented gas heathers. Washington, DC: News from CPSC, January 18, 1980.

  4. Rench JD, Savage EP. Carbon monoxide in the home environment--a study. Journal of Environmental Health, 1976;39:104-6.

  5. Allegheny County Health Department. Carbon Monoxide Action Program, 1976. (unpublished report)

  6. U.S. General Accounting Office. Indoor air pollution: an emerging health problem. Gaithersburg, Maryland: Report to the Congress of the United States, (CEC-80-111), 1980.

  7. New Mexico Environmental Improvement Agency. Carbon monoxide hazard reduction in recreational vehicles project--final report. Atlanta: Prepared for the Centers for Disease Control, (Contract No. 200-76-0616), 1977.

  8. CDC. Carbon monoxide fact sheet. Atlanta: U.S. Public Health Service, Centers for Disease Control 1976. *Environmental Protection Agency (EPA) standards for CO are identified at levels of 9 ppm, 8-hour exposure, and 35 ppm, 1-hour exposure, neither to be exceeded more than once per year. EPA is currently considering revisions of these standards.

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