Open air carbon monoxide poisoning in a child swimming behind a boat

Carbon monoxide (CO) poisoning is the most common fatal poisoning in the United States. The circumstances often involve an unsuspected increase of CO in an enclosed environment. Victims often are unaware that their activity or environment placed them at risk for CO poisoning. The possibility of open air CO poisonings was first reported in 1987. We present a case of open air CO poisoning resulting in neurologic depression and a markedly elevated carboxyhemoglobin level in a child who had been swimming behind a house boat. Emergency physicians and pediatricians should be aware of the possibility of accidental open air CO poisoning in children and adults who swim around recreational boats.