Emergency room visits because of heart attacks appear to have dropped sharply across the state after the beginning of 2010, and health officials think one reason is the ban on smoking in bars and restaurants that took effect then.
Such visits fell 21 percent after the law went into effect, according to a report released Wednesday by the N.C. Division of Public Health.
The statistical modeling used to generate that number couldn't take into account everything that cut heart attack rates, but the ban almost certainly played a big part, said Dr. Jeffrey Engel, the state health director.
A drop that large would be in line with similar improvements seen elsewhere in the country where such regulations were enacted, Engel said.
Tobacco opponents have been citing such results as cause for expanding smoking bans to protect employees at other kinds of businesses.
Many people understand that tobacco smoke can cause lung cancer and other health problems such as emphysema. It's not as widely known, though, that even brief exposure to tobacco smoke can trigger a heart attack in those with heart disease or who are at risk for it, said Sally Herndon, head of the Tobacco Prevention and Control Branch of the state public health division.
Chemicals in the smoke narrow blood vessels and raise blood pressure and pulse rates, and cause chemical changes in the blood that make cardiovascular problems including heart attacks more likely, according to the U.S. Surgeon General's office.
Engel cited a case where smoking was banned in Helena, Mont., and heart attack rates promptly fell.
Then the ban was overturned, and the rates rose again.
Researchers say the modeling methods used in the state report were similar to those used in studies around the world. There are caveats, though. For one, the data only went back as far as 2008, making it difficult to look at long-term trends.
Also, a simple table of yearly totals of emergency room visits for heart attacks included in the study shows that the number of visits also fell in 2009, before the smoking ban took effect.
And the yearly total of heart attacks among women actually increased in 2010, according to the table.
There were many changes going on during that period that explain why the rates would also drop in 2009, Engel said, such as the fact that some restaurant and bar owners had already banned smoking.
Still, state officials touted the new numbers as a sign of the law's impact.
"We pushed for passage of this law because we knew it would save lives," Gov. Bev Perdue, who signed the law into effect, said in a statement. "Our goal was to protect workers and patrons from breathing secondhand smoke, and we are seeing positive results."
Similar laws were in place in dozens of other states earlier. Given North Carolina's status as the nation's top tobacco producer, though, the law here triggered national headlines when it was enacted.
It also sparked opposition from some bar and restaurant owners who feared it would cut into their profits. A lawsuit by a Greensboro pool hall owner seeking to overturn part of the ban was rejected in July by the state Court of Appeals.