In cases of intentional carbon monoxide poisoning the diagnosis is usually straightforward and is suggested by the circumstances in which the patient is found. In contrast, accidental carbon monoxide poisoning remains underdiagnosed because the source of carbon monoxide is often not obvious and may be remote and because the symptoms of poisoning—headache, lethargy, nausea, and vomiting—are non-specific.

In the United States a review of death certificates over 10 years identified 56 133 deaths in which carbon monoxide poisoning was implicated.1 Of these, 46% were suicide, 28% were associated with burns, and 21% were unintentional for other reasons. Fifty seven per cent of these last unintentional deaths were related to exhaust fumes from a motor vehicle, which in most cases was stationary. A three year study of carbon monoxide poisoning in France identified 735 cases, of which 196 had domestic causes.2 The domestic sources of carbon monoxide were water heaters (57%), boilers (21%), coal stoves (9%), braziers (4%), cookers (2%), and heating devices (1.5%). In addition, reports of carbon monoxide poisoning due to poorly maintained or poorly ventilated domestic appliances have come from Switzerland,3 Denmark,4 5 and Belgium.6 In one report of domestic carbon monoxide poisoning from the United States patients were poisoned far from the source of the gas: carbon monoxide had been drawn into a motel's air conditioning system from the heating vents of a nearby swimming pool.7

The indoor use of cooking devices designed for outdoor use is also an important cause of carbon monoxide poisoning. Foutch and Henrichs reported the death due to …