The perils associated with passive smoking have often been cited as reasons to seek a complete ban on smoking in public places, but a new study claims that the dangers of second hand smoke have been exaggerated.

In a new study, long time American anti-tobacco activist and physician Dr Michael Siegal has expressed grave concern over the 'obfuscation of facts' about second-hand smoke.

"The inaccuracies lie in overstating the effect of a single, transient exposure to second hand smoke-- a claim which cannot be validated by any scientific evidence," he says.

Siegal contends that only repeated exposure to second hand smoke is likely to increase the risk of a heart attack for a non-smoker.

"As far as the actual possibility of causing a heart attack is concerned, it is all the more unlikely. For that matter, even chronic exposure to second-hand smoke cannot cause a heart attack in a healthy non-smoker," he said.

Drawing parallels between eating a single fatty meal and being exposed to second hand smoke for 20-30 minutes, he said, "The 30 and 20 minute claims were based on studies that observed merely changes in the heart's functioning."

Siegal goes on to explain how all cardiac risks posed by exposure to second-hand smoke are in fact, reversible, that is a little while after the non-smoker is removed from the smoking environment, the heart resumes its prior state of functioning.

Siegal says that the argument that second-hand smoke "can raise a non-smoker's risk of suffering a fatal heart attack to that of a smoker" seems unfounded since only people with a history of severe coronary disease or asthma are likely to suffer any serious damage from such a transient exposure to second-hand smoke.

According to experts back home, however, whatever be the proven or non-proven basis of such arguments, smoking in public places should be avoided at any cost.

"No argument should deter me from not smoking in front of my family and co-workers," said Dr Ravi Kasliwal, senior cardiologist with the Indraprastha Apollo Hospital.

Growing evidence about the health risks of passive smoking has prompted many countries to ban smoking in public areas.