The number people suffering heart attacks in Europe and North America has dropped by between a quarter and more than a third thanks to smoking bans, according to two major studies.
Anti-smoking laws have had a bigger impact than expected, and thousands of lives have already been saved by stopping people smoking in public places, according to the studies.
Every year in the UK around 275,000 people suffer from heart attacks, with around 146,000 dying as a result. It had earlier been revealed that heart attack figures in the UK fell by around 10% after the introduction of the smoking ban in July 2007.
A Department of Health study has reported an even sharper drop than expected, and research has shown heart attack figures in Scotland dropped by 14% after introducing the ban in 2006.
In the US, the number of heart attacks fell by 26%, according to a study published in the Journal of the American College of Cardiology.
Professor David Meyers, of the University of Kansas School of Medicine, said inhaling a small amount of cigarette smoke increases the risk of having a heart attack.
He said: "Public smoking bans seem to be tremendously effective in reducing heart attack and, theoretically, might also help to prevent lung cancer and emphysema, diseases that develop much more slowly than heart attacks."