Researchers have found that a ban on smoking in American bars has increased the number of accidents from drunken driving.
US jurisdictions with a smoking ban have seen, on average, a nearly 12-percent rise in the number of drink-related accidents at the wheel, they say in a study released on Wednesday.
Instead of heading to their local bar for a drink and a smoke, smokers venture farther afield in search of a place where lighting up is still allowed, they say.
The smokers may not be drinking more than before but they are certainly driving more -- and this is what is increasing the risk of a smash.
"Banning smoking in bars increases the fatal accident risk posed by drunk drivers," the study says.
"Our evidence is consistent with two mechanisms -- smokers searching for alternative locations to drink within a locality and smokers driving to nearby jurisdictions that allow smoking in bars."
The ban is spreading across the United States, but in a piecemeal fashion. According figures cited in the report, nearly a one-third of the US population lives in cities, counties or states where there are restrictions.
Study authors Scott Adams and Chad Cotti, of the University of Wisconsin, say that the increase in drunk driving has to be weighed against "potential positive health impacts" from smoking bans, and this may take years to determine.
Their paper appears in the Journal of Public Economics. It is based on analysis of data from 2000 to 2005, drawn from counties that enforced a ban during this period and from accident statistics before and after the ban was introduced.