Smoking ban in Madison
Wisconsin's uniform ban on indoor smoking in public places began in July 2010. State Journal archives

The percentage of Wisconsin residents who say they're exposed to tobacco smoke dropped by nearly half after the state's workplace smoking ban started two years ago, a new study says.

The law, which took effect on July 5, 2010, banned smoking in bars, restaurants, private clubs, schools, hotels, clinics and other workplaces.

Before the ban, 55 percent of residents reported being exposed to smoke outside the home and 13 percent at home. After the ban, 32 percent reported exposure to smoke outside the home and 7 percent at home.

"This state ban was an effective public policy to improve health," said Dr. Javier Nieto, chairman of the UW School of Medicine and Public Health's Department of Population Health Sciences.

Nieto said the reduction in exposure to secondhand smoke should reduce people's risk of asthma, cancer and heart disease, though the obesity epidemic is increasing the risk of some cancers and heart disease.

The study was part of the medical school's Survey of the Health of Wisconsin, an annual assessment of state residents on a range of health conditions. The findings, by a team led by UW medical student Alexis Guzman, will be published in the August issue of the Wisconsin Medical Journal.

The percentage of residents surveyed in the second half of 2010 who reported exposure to smoke was cut by nearly half compared to people surveyed from June 2008 to June 2010. Data for 2011 and this year haven't been analyzed.

Eighty percent of the post-ban group said they had no-smoking policies in their homes, up from 74 percent in the pre-ban group.

But smoking rates went up slightly, to 19 percent after the ban from 18 percent before it, a difference that is not statistically significant.

"Changes in smoking behavior take more time," Nieto said.

A 2010 study by the UW Carbone Comprehensive Cancer Center showed a 92 percent improvement in air quality samples in bars and restaurants after the ban.

A poll in June 2011 found 75 percent of state residents support the law, up from 69 percent in 2008 when the Legislature debated the proposal. Less than 1 percent of businesses have had compliance problems with the law, with 149 cited from July 2011 to May, according to the state Department of Health Services.

Sales at restaurants and taverns increased 1 percent in 2010 and 2 percent last year, according to the Wisconsin Restaurant Association. The subcategory of bars and taverns saw a decrease of about 4 percent.

The ban "wasn't a boon to our industry, but it doesn't seem to have hurt our sales," said Pete Hanson, a spokesman for the restaurant association.

— The Associated Press contributed to this report.