Pharmacies would be overrun if a new drug came on the market that reduced the rate of heart attacks by 33 percent.

While this medical intervention does exist, it doesn't come in pill form. Instead, it's a public policy -- smoke-free workplace laws, such as Minnesota's 2007 Freedom to Breathe Act, whose value regrettably continues to be challenged on ideological grounds. A recent commentary appearing on these pages -- one that recycled arguments about government overreach -- was one of the latest salvos.

But a new study led by Mayo Clinic's Dr. Richard Hurt serves up more evidence that existing smoking bans not only make sense but should be adopted more widely. The team of researchers filled in an important research gap on smoking bans' value. In 2009, an Institute of Medicine committee combed through existing studies and concluded "there is a causal relationship between smoking bans and decreases in acute coronary events.'' But the committee didn't quantify the risk reduction, and it quibbled with some studies' design.

The population-based study from Hurt's team did come up with numbers. They also used Minnesota's renowned medical databank -- the Rochester Epidemiology Project -- which should minimize scientific quibbling.

Researchers found that the incidence of heart attacks decreased by 33 percent in Olmsted County after smoke-free laws were put in place there beginning in 2002. Researchers ruled out other explanations, such as growing use of automated external defibrillators. The study appeared in the Archives of Internal Medicine.

Studies of smoking bans in other areas have documented decreases in heart attack hospitalizations. This impressive body of work not only justifies smoking bans' value, but underscores the danger of secondhand smoke. Breathing it in has immediate cardiovascular effects. There is no risk-free dose, according to a 2006 U.S. surgeon general's report. Public safeguards are sensible, and more laws like Minnesota's are needed.