Updated

About half of the U.S. population is affected by smoke-free workplace laws.

But many health advocates believe this is not nearly enough. Now, a new study has bolstered their argument. The study, published in the Archives of Internal Medicine, found these laws are associated with a sharply reduced incidence of heart attacks.

Researchers from the Mayo Clinic in Rochester, Minn., examined medical records of patients in Olmsted County, Minn., before and after two smoke-free laws went into effect there.

The first, in 2002, banned smoking in restaurants (but not bars). The second, implemented in 2007, was a comprehensive smoking ban in all workplaces (including bars).

The researchers compared rates of heart attack and sudden cardiac death in the county 18 months before and 18 months after each of the laws went into effect. The rate of heart attacks dropped 34 percent between the time prior to the comprehensive law was implemented and 18 months after. There was also a 17 percent decline in the incidence of sudden cardiac death for the overall study period from about 2001 until 2009.

Incidentally, during that same period, the prevalence of diabetes and obesity, two risk factors for heart disease, increased, and the prevalence of hypertension and high cholesterol remained flat. The rate of smoking did decline somewhat during that time, but not in those who actually had a heart attack or sudden cardiac death.

The results suggest that smoke-free workplace laws, not other lifestyle and diet factors, were responsible for the steep decline in heart attacks, the authors of the study wrote.

Second-hand smoke has long been associated with heart disease in nonsmokers. Research suggests that the cardiovascular effects of second-hand smoke are nearly equal to those of active smoking. Studies have shown damage to arteries and other adverse effects after only 30 minutes of exposure to second hand smoke.

Prior studies have also shown a reduced risk of heart disease after smoke-free workplace laws have gone into effect, but this study has more complete data said the study’s lead author, Dr. Richard D. Hurt, of the Nicotine Dependence Center and department of internal medicine at the Mayo Clinic.

Currently, 23 states have comprehensive smoke-free workplace laws in place, as do many cities and counties in those states that don’t have laws, according to Americans for Nonsmokers' Rights, an advocacy group. Those laws cover an estimated 49 percent of workers.

Some laws have also pushed for bans in the outdoor areas surrounding office buildings, meaning you can’t just duck outside your building for a smoke—you’d have to go further afield.

“The 2006 Surgeon’s General report says there is no safe level of exposure,” Hurt said.

Smoke-free workplace laws not only benefit the health of workers, but studies have shown they can help smokers reduce the amount of cigarettes they smoke, and increase quitting rates. They also are associated with people voluntarily having smoke-free policies at home, particularly the homes of smokers.