Laws that mandate smoke-free workplaces are associated with a significantly reduced risk of heart attacks, according to a new study by researchers at the Mayo Clinic.

The researchers looked at medical records of patients before and after two smoke-free laws went into effect in Olmstead County, Minnesota. One law, implemented in 2002, banned smoking in restaurants, but not bars. The second law, implemented in 2007, banned smoking in all workplaces, including bars, Fox News reports.

They compared rates of heart attack and sudden cardiac death 18 months before and after each law went into effect. They found heart attack risk decreased about 34 percent from the 18 months before the first smoke-free law was implemented, to the 18-month period afterwards. They also found a 17 percent decline in the incidence of sudden cardiac death between 2001 and 2009.

The rate of smoking declined overall during the study period, but not in those who had a heart attack or sudden cardiac death, the researchers found.

“We now know that not only do smoke-free workplace laws help avoid having a heart attack, but they also reduce the chances of having sudden cardiac death,” lead author Dr. Richard Hurt said in a news release. “Those are both very dramatic things that have a very big impact on workers as well as patrons.”

All people should avoid secondhand smoke to the extent possible, and people with coronary heart disease should have no exposure to secondhand smoke, the researchers advise in the Archives of Internal Medicine.