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Detectable by commercial radioimmunoassay or enzyme immunoassay tests. Carbon Monoxide Poisoning -- South Dakota

On October 17, 1984, a physician of the Pierre (South Dakota) Service Unit, Indian Health Service, reported a nighttime incident of poisoning by an unknown substance involving a family of six that resided in a newly renovated, well-insulated house.

Shortly after midnight, the mother and two youngest children were taken by ambulance to a local hospital, with symptoms of nausea, dyspnea, vomiting, tachycardia, cyanosis, and faintness. Around 1:00 a.m., the mother called home and learned that the oldest child had developed similar symptoms. A second call, 45 minutes later, found the father and second oldest child to be symptomatic also. All family members were evacuated and recovered without treatment.

On October 18, the district and service unit sanitarians visited the house to search for hazardous conditions. Also present were the tribal housing authority director, a liquid propane gas dealer, and the furnace dealer. Before arrival, the heat had been turned off, and the house ventilated. MSA carbon monoxide (C0) dosimeters were placed in one bedroom and in the living room. Within 1 hour of closing the windows and starting the furnace, high levels of CO (35 or more parts per million (ppm))* were detected in the two rooms. Examination of the furnace and water heater (both propane-fired) revealed improper venting and faulty furnace operation. The air shutters on the furnace burners were closed to such an extent that sufficient air supply was precluded, causing incomplete combustion. As a consequence, soot accumulated in the combustion chambers' flues to the extent that proper venting/drafting became impossible. The products of combustion then leaked from the furnace into the basement air, where they were drawn into the air-return duct and disseminated throughout the house.

The system was rectified by providing sufficient air to the burners, cleaning the soot from the flues, and closing the basement intake vent in the air-return duct. Reported by D Mosier, R Baldwin, Pierre Svc Unit, Office of Environmental Health, Indian Health Svc, Health Svcs and Mental Health Administration, US Public Health Svc; Investigations Section, Special Studies Br, Chronic Diseases Div, Center for Environmental Health, CDC.

Editorial Note

Editorial Note: Despite efforts to reduce the number of unintentional CO poisonings through public education, standards, and improved product design, nonfatal and fatal CO poisonings continue to occur. Each year, an estimated 10,000 persons in the United States seek medical attention because of exposure to CO gas, and approximately 1,500 die from CO poisoning (1).

CO is a common gas produced by the incomplete combustion of any carbon-containing or organic solid, liquid, or gaseous fuel. The amount of CO produced during fuel burning is increased by incorrect air-fuel mixture, insufficient ventilation of combustion gases, and insufficient intake of fresh air. Although CO is odorless, colorless, tasteless, and nonirritating, it is often combined with other products of combustion that may produce a sharp odor and may irritate the eyes (1,2). CO exerts its toxic effect by binding to circulating hemoglobin in the lungs to reduce the oxygen-carrying capacity of the blood. Hemoglobin absorbs CO over 200 times more readily than oxygen (3). CO-bound hemoglobin, called carboxyhemoglobin (COHb), is unavailable to transport oxygen. Exposure to low levels of CO causes headache, dizziness, and sleepiness. Continued exposure brings on nausea, vomiting, and heart palpitation. Prolonged exposure to high levels of CO causes unconsciousness or death. Death can occur when blood contains from 60% to 80% COHb (4).

Because CO is one of the most widely encountered toxic gases, an understanding of hazard prevention and of the symptoms that result from exposure is necessary for preventing CO poisonings (5). Symptoms of low-level exposure should always be considered a warning of a potentially serious problem. If CO exposure is suspected, the health department should be contacted, and the dwelling in question should be inspected.

To prevent CO poisoning, the air inlet to any device that burns fuel must be properly adjusted and regularly cleaned. If the air inlet to such equipment is improperly adjusted, or the inlet is blocked by dirt, soot, or grease, the amount of CO produced will increase sharply. Sufficient ventilation of combustion gases to the outside air is also critical. One should periodically inspect vents for defects and obstructions and ensure that all horizontal vent pipes rise steadily from the appliance to the chimney. Annually, a qualified technician should adjust all fuel-burning appliances for correct fuel-air mixture, proper ventilation of combustion gases, and sufficient fresh-air intake (1).

Other prevention recommendations include: (1) never burn charcoal inside the home or in confined spaces; (2) never use a gas oven to warm a room; (3) never burn anything in an improperly vented stove or fireplace; (4) never run an automobile engine, lawn mower, or any combustion engine in an enclosed area; and (5) always ensure adequate natural ventilation for portable, fuel-fired space heaters.


  1. CDC. Carbon monoxide fact sheet. Atlanta, Georgia: Centers for Disease Control, 1976.

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

  3. CDC. Carbon monoxide poisoning--New York City. MMWR 1979;28:87-8.

  4. CDC. Carbon monoxide intoxication--a preventable environmental health hazard. MMWR 1982;31:529-31.

  5. CDC. Unpublished data. *There are currently no indoor air pollution standards. However, the U.S. Environmental Protection Agency ambient air quality standards for CO are: 9 ppm, maximum 8-hour concentration, and 35 ppm, maximum 1-hour concentration, neither to be exceeded more than once per year.

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