Enacting city smoking bans appears to increase drunken driving, according to a new national study of arrests by Wisconsin researchers.

Fatal accidents involving alcohol increased after communities banned public smoking, the study to be released by the Journal of Public Economics found. The authors attributed the increase to people driving farther to drink, either to a place with an outdoor smoking area or a city without a ban.

“The increased miles driven by drivers who wish to smoke and drink offsets any reduction in driving from smokers choosing to stay home after a ban, resulting in increased alcohol-related accidents,” the study says.

The researchers, Scott Adams, of the University of Wisconsin-Milwaukee, and Chad Cotti, now at the University of South Carolina, said they were surprised by the results.

“We thought we would see a reduction,” Adams said. “Our first thought was, ‘Throw it away, it must be wrong.’”

But it wasn’t, he said.

The study looks at highway fatalities from 2001 to 2005 involving at least one driver with blood alcohol content over 0.08. It compares those in cities and counties with bans to crashes in surrounding areas without bans. It found an increase in accidents after smoking bans were enacted, both in ban areas and near boundary lines.

Smoke Free Wisconsin Executive Director Maureen Busalacchi objected to linking the increase in accidents to smoking bans, saying people may travel to drink for many reasons.

“How in the world you would figure out where people are traveling unless you are interviewing them?” she asked.

The results were similar nationwide, except in New England, which has many smoking bans, Adams said. A well-enforced national smoking ban would get rid of the drunken driving increases because people would have no reason to travel to drink, he said.

The study did not include Wisconsin because Appleton and its ban covered too small an area and data collection started before Madison banned smoking in 2005, Adams said.

Fitchburg’s smoking ban started April 1, and Eau Claire’s will start July 1. Marshfield residents approved a ban Tuesday that will become law within 30 days.