Smoke-free workplaces not only protect non-smokers from the dangers of passive smoking - they can also encourage smokers to think twice about their habit.

Researchers in San Francisco, California, found that smokers who worked in companies with a no-smoking policy tended to either cut back on their consumption, or give up smoking completely.

This would actually be a quite a simple way to save lives

Marsha Williams

On average, the introduction of a smoke-free policy led to a cut in cigarette consumption of 29%, and a 4% drop in the total number of people who smoked.

The researchers, from the Center for Tobacco Control, Research and Education at the University of California, based their findings on a review of 26 studies from across the world which examined the effects of smoke-free workplaces.

Taxes

They say the policy is much more effective than trying to cut smoking rates by increasing tax on tobacco products.

To achieve a similar result, they estimate, the price of tobacco would have to soar by 73%.

The researchers also estimate that if all UK workplaces became smoke-free, the average number of cigarettes smoked would drop by 7.6%.

This would cost the tobacco industry �310m annually in lost sales.

Writing in the British Medical Journal, they say: "This loss in revenues explains why the industry fights so hard against legislation to ensure that workplaces become smoke-free.

"Smoke-free workplaces not only protect non-smokers from the dangers of passive smoking, they also encourage smokers to quit or to reduce consumption."

The researchers found that the introduction of a completely smoke-free workplace was about twice as effective at cutting smoking rates as a policy that allowed smoking in some areas.

Millions of smokers

It is estimated that 11 million people in the UK smoke, and that 3 million non-smokers are exposed to passive smoking in the workplace.

Marsha Williams, from the anti-smoking charity Action on Smoking and Health (ASH) said it was time that the government introduced legislation to ban smoking at work.

However, it had failed to act on a report from the Health and Safety Commission, which recommended such a policy in 2000.

She said: "The government seems to prioritise the concerns of small businesses and the hospitality industry, who say it would be difficult to implement, over and above people's health.

"This would actually be a quite a simple way to save lives."

A Department of Health spokeswoman said: "We are taking action to ensure that smokers are aware of the effects their habit has on those around them.

"The Public Places Charter is encouraging the provision of smoke free places to eat and drink and Local Tobacco Alliances are being specifically funded to develop projects tackling passive smoking."