THURSDAY, Oct. 15 (HealthDay News) -- Bans on smoking in public places really do work at reducing heart attacks from secondhand smoke, a major study finds.

Smoke-free policies can reduce the risk of heart attack by up to 47 percent and significantly reduce the likelihood of other heart problems, according to a report released Thursday by the U.S. Institute of Medicine (IOM).

The report also found compelling evidence that even a brief exposure to secondhand smoke can trigger a heart attack.

"We did conclude a cause-and-effect relationship exists between heart disease and secondhand smoke exposure," Dr. Lynn R. Goldman, chairwoman of the IOM committee, said during a press conference Thursday.

Also, sufficient evidence exists to support a cause-and-effect relationship "between exposure to secondhand smoke and heart attacks or acute coronary events," said Goldman, a professor of environmental health sciences at Johns Hopkins Bloomberg School of Public Health.

Moreover, the more secondhand smoke you are exposed to, and the longer you're exposed to it, the greater the risk for heart problems or heart attack, Goldman said.

In the United States, about 43 percent of nonsmoking children and 37 percent of nonsmoking adults are exposed to secondhand smoke. Despite efforts to decrease exposure to secondhand smoke, about 126 million nonsmokers were still breathing others' smoke in 2000, according to the report.

In 2006, a U.S. Surgeon General's report confirmed the link between involuntary exposure to tobacco smoke and heart disease, and it determined that smoke-free policies were an inexpensive and effective way to reduce exposure.

But whether smoking bans actually reduced heart disease has been an ongoing debate, according to the IOM.

This new report puts that issue to rest, said Danny McGoldrick, vice president for research at Campaign for Tobacco-Free Kids. Not only does it document that smoke-free laws result in fewer heart attacks, it may also help get more states and localities to pass smoke-free legislation, he said.

"If policy makers are paying attention to the science, and this is one more piece of evidence that says 'you can actually save people's lives, save health-care costs,' then those states that have yet to act should do so," he said. "How many dramatic findings do you need before you are finally going to act to protect everybody's right to breathe clean air?"

To reach its conclusions, the IOM reviewed published and unpublished data and heard testimony about the association between secondhand smoke and heart problems.

Studies showed that smoking bans cut heart attacks by anywhere from 6 percent to 47 percent. Given the wide range, the IOM could not precisely determine the risk reduction, but said the benefits were obvious.

Other studies concluded that breathing secondhand -- or "environmental" -- smoke increased risk for heart problems by 25 percent to 30 percent, the report found.

While there was no direct evidence that brief exposure to secondhand smoke could trigger a heart attack, indirect evidence supported this conclusion, the study found.

Data on smoke from other pollution sources suggest that even a relatively brief exposure to particulate matter can cause a heart attack, and particulate matter is a component of secondhand smoke, the report noted.

"This report makes it increasingly clear that smoke-free policies are having a positive impact in reducing the heart attack rate in many communities," Dr. Clyde Yancy, president of the American Heart Association, said in a prepared statement.

"There's no question that secondhand smoke has an adverse health impact in workplaces and public environments. We must continue to enact comprehensive smoke-free laws across the country to save lives and reduce the number of new smokers," he said.

Dr. Stanton Glantz, a professor of medicine and director of the Center for Tobacco Control Research and Education at the University of California, San Francisco, welcomed the findings.

Because the IOM is cautious and conservative, the report should be taken seriously, Glantz said. "This should shut up the people who have been whining and saying the evidence isn't there," he said.

"Not only do you get an immediate reduction in risk of heart attacks when you put these smoke-free policies into effect, but the effect grows over time," he said.

Glantz said he expects that the findings will influence policy and get more places to enact smoke-free laws. "If they want to prevent heart attacks, they should," he said.

More information

For more on secondhand smoke, visit the U.S. National Library of Medicine.

SOURCES: Danny McGoldrick, vice president for research, Campaign for Tobacco-Free Kids; Stanton Glantz, Ph.D., professor of medicine, Center for Tobacco Control Research and Education, University of California, San Francisco; Oct. 15, 2009, teleconference with Lynn R. Goldman, M.D., M.P.H., Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore; Oct. 15, 2009, Institute of Medicine report, Secondhand-Smoke Exposure and Cardiovascular Effects: Making Sense of the Evidence; Oct. 15, 2009, news release, American Heart Association

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