By Ben Harder
Following a series of deaths and hospitalizations from carbon monoxide poisoning on an Arizona waterway, medical investigators have established that large congregations of motorboats can produce enough of the invisible, odorless gas in open air to be hazardous to people.
Investigations along Bridgewater Channel at Lake Havasu City, Ariz., began after two deaths and eight hospitalizations occurred among carbon monoxide–poisoned vacationers between 1997 and 2002. An additional fatality and four serious poisonings have happened since then on boat decks or in nearby water.