Ambulance calls from casinos dropped significantly in Colorado after the state extended its smoke-free law to casino floors, a new study concludes.

The study included 16,600 ambulance calls over 12 years in Gilpin County, Colorado, which has more than two dozen casinos. In 2006, the state enacted a law that banned smoking in workplaces, restaurants, bars and other public spaces, but not in casinos. After the law was enacted, ambulance calls dropped almost 23 percent in places where smoking was prohibited, but there was no significant change in calls from casinos that allowed smoking.

In 2008, the state extended the smoking ban to include casinos, and ambulance calls from casinos decreased almost 20 percent, while calls from other locations remained stable. “The message to policymakers is clear: stop granting casinos exemptions,” researcher Stanton Glantz of the University of California, San Francisco, said in a news release.

“The research shows strong evidence of a significant drop in ambulance calls due to less secondhand smoke exposure,” Glantz said. “Inhaling secondhand smoke increases the likelihood of dangers with blood clots and makes it more difficult for arteries to expand properly – changes that can trigger heart attacks. Legislative and tribal exemptions for casinos, which are all too common, are potentially putting employees and customers at risk of secondhand smoke exposure.”

Most smoke-free laws around the country partly or completely exempt casino floors, The Philadelphia Inquirer reports.

The study findings appear in the journal Circulation.