CHICAGO, June 9 (Xinhua) -- Laws that ban smoking at workplaces and other public places are associated with a significantly lower risk of cardiovascular disease, a study of Northwestern University (NU) found.

To be specific, the study found that smoke-free policies in workplaces were linked to a nearly 50 percent reduction in the risk among middle-aged adults, while that for bars and restaurants were associated with a reduction of around 25 percent.

The study linked data from participants in the CARDIA (Coronary Artery Risk Development in Young Adults) study to state, county and local 100 percent smoke-free policies in bars and restaurants and non-hospitality workplaces. The data included 3,783 adults, both black and white, with a median follow-up of 20 years.

"Our results suggest smoke-free policies may prevent cardiovascular disease among young to middle-aged adults," said Stephanie Mayne, a postdoctoral fellow at Nu's Department of Preventive Medicine.

Only 25 U.S. states have laws banning smoking in all workplaces, bars and restaurants.

The researchers are now examining whether smoke-free policies are associated with reductions in blood pressure among non-smokers, which may be a potential mechanism for the influence of such polices on cardiovascular disease risk.

The study has been published in Circulation.