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Why blame the virtual world for the problems of the real world?
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Mahesh Butt
Bollywood producer
In a report to be released on Tuesday in Geneva, the organisation also said it used to be mostly bad guys who smoked.
But now more than half of Bollywood heroes were also shown lighting up in films.
Prominent Bollywood film producer Mahesh Bhatt said the authorities should target the tobacco industry, not films, if they wanted to combat smoking.
"Impose a ban on them rather than blame the film world," he told the BBC.
"If film stars could change the world this planet could have become a paradise by now."
Morality question
The United Nations' health body studied Bollywood films released in the last 10 years.
More than three-quarters of the films showed tobacco use of some sort, mostly cigarettes, its report said.
Most on-screen smokers were still men. Where women were shown smoking, they tended to be bad characters, such as women with dubious morals.
But the image of the male smoker has changed.
In the old days, it was almost entirely villains who smoked. Now more than half of Bollywood's male heroes are lighting up too.
The health study also claimed a direct link between smoking on-screen and teenage smoking in real life.
It said teenagers who watched films that showed stars smoking became three times more likely to try cigarettes.
Cultural influence
It also said teenagers whose favourite star smoked on screen were sixteen times more likely to have positive attitudes towards cigarettes.
It is estimated that 15 million people a day watch Bollywood films, either at the cinema or on television. Many see the stars as a leading cultural influence.
India now accounts for almost a third of the world's smoking-related deaths.
The health organisation is now calling on Bollywood to end on-screen smoking altogether.