Carbon Monoxide Poisoning Deaths Associated with Camping -- Georgia, March 1999

Carbon monoxide (CO) is an odorless, colorless, nonirritating gas produced by the incomplete combustion of carbon-based fuels. CO exposure is responsible for more fatal unintentional poisonings in the United States than any other agent, with the highest incidence occurring during the cold-weather months (1). Although most of these deaths occur in residences or motor vehicles (2), two incidents among campers in Georgia illustrate the danger of CO in outdoor settings. This report describes the two incidents, which resulted in six deaths, and provides recommendations for avoiding CO poisoning in outdoor settings.

Cases 1-4. On the afternoon of March 14, 1999, a 51-year-old man, his 10-year-old son, a 9-year-old boy, and a 7-year-old girl were found dead inside a zipped-up, 10-foot by 14-foot, two-room tent at their campsite in southeast Georgia (a pet dog also died). A propane gas stove, still burning, was found inside the tent; the stove apparently had been brought inside to provide warmth. The occupants had died during the night. Postmortem carboxyhemoglobin (COHb) levels measured 50%, 63%, 69%, and 63%, respectively, in the four decedents (in the general U.S. population, COHb concentrations average 1% in nonsmokers and 4% in smokers [3]).

Cases 5 and 6. On March 27, 1999, a 34-year-old man and his 7-year-old son were found dead inside their zipped-up tent at a group camping site in central Georgia. They were discovered by other campers just before 9 a.m. A charcoal grill was found inside the tent; the grill apparently had been brought inside to provide warmth after it had been used outside for cooking. Postmortem COHb levels in the two campers measured 68% and 76%, respectively.

Reported by: R Wheeler, Covington; MA Koponen, MD, Georgia Bur of Investigation; AB John-son, MPH, PJ Meehan, MD, District 3-4, Newton County Health Dept, Covington; SE Lance-Parker, DVM, KE Powell, MD, Div of Public Health, Georgia Dept of Human Resources. Environmental Hazards Epidemiology Section, Health Studies Br, Surveillance and Programs Br, Air Pollution and Respiratory Health Br, Div of Environmental Hazards and Health Effects, National Center for Environmental Health; Div of Applied Public Health Training, Epidemiology Program Office; and EIS officers, CDC.

Editorial Note:

On respiration, CO binds to hemoglobin with an affinity 200-250 times greater than that of oxygen, forming a COHb complex (4). The principal toxic effect of CO exposure is tissue hypoxia because COHb is less efficient at transporting and delivering oxygen. Poisoning symptoms, such as headache, dizziness, and nausea, usually are seen at COHb levels of greater than 10% in otherwise healthy persons (2).

During 1979-1988 in the United States, from 878 to 1513 deaths per year were attributed to unintentional CO poisoning (1). CO poisoning has been reported in many different settings, including homes (5), automobiles (6), and indoor arenas (7). The findings in this report demonstrate the danger of CO from portable gas stoves and charcoal grills, specifically if placed inside a tent or other confined sleeping area. In the United States during 1990-1994, portable fuel-burning camp stoves and lanterns were involved in 10-17 CO poisoning deaths each year, and charcoal grills were involved in 15-27 deaths each year (2). During this same time, an annual average of 30 fatal CO poisonings occurred inside tents or campers (2).

Evening temperatures often drop unexpectedly, even during warmer months of the year. Campers who are unprepared for colder weather may overlook the danger of operating fuel-burning camping heaters, portable gas stoves, or charcoal grills inside tents and campers. Camping stoves and heaters are not designed to be used indoors and can emit hazardous amounts of CO, and smoldering charcoal emits large amounts of CO. Inside a tent or camper, these sources produce dangerous concentrations of CO, which becomes even more dangerous to sleeping persons who are unable to recognize the early symptoms of CO poisoning.

To avoid hazardous CO exposures, fuel-burning equipment such as camping stoves, camping heaters, lanterns, and charcoal grills should never be used inside a tent, camper, or other enclosed shelter. Opening tent flaps, doors, or windows is insufficient to prevent build-up of CO concentrations from these devices. When using fuel-burning devices outdoors, the exhaust should not vent into enclosed shelters. Warnings about the potential for CO poisoning should be stated clearly in the owner's manual and on labels permanently affixed to portable stoves. In 1997, changes made in the labeling requirements for retail charcoal containers* more clearly conveyed the danger of burning charcoal inside homes, tents, or campers. Rather than relying on fuel-burning appliances to supply heat, campers should leave home with adequate bedding and clothing and should consume extra calories and fluids during the outing to prevent hypothermia. Continuing efforts to educate the public by organizations that promote outdoor activities or operate camping areas also should decrease camping-associated CO poisoning.

References

1. Cobb N, Etzel RA. Unintentional carbon monoxide-related deaths in the United States, 1979 through 1988. JAMA 1991;266:659-63.
2. Ault K. Estimates of non-fire carbon monoxide poisonings and injuries. Washington, DC: US Consumer Product Safety Commission, 1997.
3. Radford EP, Drizd TA. Blood carbon monoxide levels in persons 3-74 years of age: United States 1976-80. Hyattsville, Maryland: US Department of Health and Human Services, CDC, National Center for Health Statistics, 1982. (Advance data no. 76).
4. Meredith T, Vale A. Carbon monoxide poisoning. Br Med J 1988;296:77-9.
5. CDC. Unintentional carbon monoxide poisonings in residential settings--Connecticut, November 1993-March 1994. MMWR 1995;44:765-7.
6. CDC. Carbon monoxide poisonings associated with snow-obstructed vehicle exhaust systems--Philadelphia and New York City, January 1996. MMWR 1996;45:1-3.
7. CDC. Carbon monoxide poisoning at an indoor ice arena and bingo hall--Seattle, 1996. MMWR 1996;45:265-7.

* 16 CFR Part 1500.

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