New York led the way, then Ireland followed suit, and now cities across the UK are being uged to ban smoking in public places. Ian Willmore argues we should call time on smoking.

SECONDHAND smoke is a killer. Whatever the tobacco industry and its allies may pretend, the science on this point is quite clear. Breathing in the smoke from other people's cigarettes is bad for your health. And it's hardly surprising either: secondhand smoke contains chemicals such as benzene, arsenic, formaldehyde, DDT and ammonia. (When I pointed this out on the radio recently, the man from the pro-smoking group FOREST said this was OK, because formaldehyde was also present in some wallpaper!)

It's hard to know for certain just how much damage secondhand smoke does. But the British Medical Association estimates at least 1,000 premature deaths a year in the UK, and many thousands of illnesses, asthma attacks and hospital visits. Secondhand smoke has been linked with heart disease, stroke and Sudden Infant Death Syndrome. It's past time for action.

Yet at least three million employees are still regularly exposed to secondhand smoke in the workplace. Most offices may be smoke free - managers long ago decided that they did not want to run the risk of breathing other people's fumes. But many small employers have not acted. And most restaurant chains and almost all pubs continue to permit smoking somewhere on their premises. Many permit it throughout.

Attempts to encourage voluntary bans have largely failed: all a pub manager needs to do to comply with the "Public Places Charter" is to stick a small sign on the door announcing that anyone can smoke anywhere on the premises.

Anyone who has ever been in a pub while it is being cleaned, and watched heavy yellow tar being scraped off the walls, will know just what our lungs are being asked to tolerate in pursuit of a pint. And if we have the slightest concern for the health of bar staff, we should find it unacceptable that many are being asked to inhale the equivalent of several cigarettes a night.

THE Health and Safety at Work Act is supposed to stop employers from continuing to expose their employees to preventable risks. The date by which all employers should have known that secondhand smoke is dangerous has certainly passed, probably sometime in the early 1990s. Therefore, any employee whose health has been damaged by secondhand smoke at work could already have a strong case for compensation. ASH and the trade union law firm Thompsons recently wrote to all the major hospitality trade employers making exactly this point. But it is clear from their replies that most employers are still crossing their fingers and hoping that none of their staff will ever get round to issuing a writ.

The attitude of some employers, and a minority of smokers, is truly shocking. ASH has been told many times that if bar staff don't like smoke "they can go and get a job somewhere else". Imagine the outcry if a construction firm said the same thing - don't force us to make building sites safer, if the staff don't like having bricks dropped on their heads they can always leave their jobs.

There's something radically wrong if people have to wait to get ill before they can go to court: the law should protect all employees from being exposed to secondhand smoke in the first place. That's why the presidents of all Britain's Royal Colleges of medicine, the Government's Chief Medical Officer, and more than 100 MPs have called on the Government to bring in a new law preventing all smoking in the workplace.

Opponents of such a law suggest that "non-smoking areas" would be a good solution to the problem. But they aren't. Smoke drifts. And employees who have to work in the remaining smoking areas will still be exposed to harm.

NOR are ventilation systems a good answer: even the most expensive systems on the market don't take all the dangerous chemicals out of the atmosphere fast or thoroughly enough to prevent damage to health. The tobacco lobby loves ventilation systems because they know that a publican who spends thousands of pounds on an expensive new system is never going to write that investment off by going smoke-free.

Opponents also argue that a ban on smoking at work and in bars and restaurants would be an unacceptable attack on the freedom of adult citizens to choose whether or not to smoke. But this is a deliberate misrepresentation of the true liberal argument: that any individual is free to do as they choose unless they do things which cause direct harm to others. Smoking does do harm to others: your freedom to smoke ends at my nose. The idea that anyone has a "right" to smoke in the presence of children, for example, is surely unacceptable. If people do choose to smoke, they should do so only when vulnerable non-smokers are not exposed to the results.

In fact, most smokers really want to give up. They know that half of all lifetime smokers will be killed by their habit. But they find it difficult because nicotine is an addictive drug as powerful as heroin. Restrictions on smoking at work are known to encourage people to quit and to stay quit. Many thousands of smokers' lives would be saved by a legal ban.

GOOD employers who give additional help and encouragement to staff who want to quit will find that they benefit too. Health Canada's study suggested that the average cost to an employer of smoking is around £1,000 a year for each employee, because of lost productivity and illness.

Smoking bans at work have already been introduced in New York and California, and are imminent in Norway, Ireland and the Netherlands. Wherever they are proposed they are bitterly fought by the tobacco lobby and its allies in the hospitality trade.

There is always a great deal of talk of impending economic disaster. The figure for lost trade, from some strange reason, is always claimed to be "30 per cent" - perhaps there is a secret tobacco industry paper advising this that has yet to be leaked to ASH. Since bars and restaurants start up and close down all the time, there are always plenty of cases which can be cited to "prove" the tobacco lobby's point.

But after a year or so, the anecdotal evidence dies away and the hard facts emerge. In New York, for example, the City Finance Commissioner Martha Stark has revealed that "New York's bars and restaurants paid the city 12 per cent more in business taxes in the months since the ban began than they did in the corresponding six-month period in 2002".

Tax figures don't lie: the smoking ban has been good for business. This just reinforces all the best economic evidence from elsewhere in the world. It's also not surprising. Most people's behaviour is not affected one way or the other if their favoured bar or restaurant goes smoke free. A small number may be put off because they can no longer smoke. A rather larger number may be encouraged to go more often, because they can now breathe in peace. Pub attendances have been falling for years. One reason may well be that customers are more and more reluctant to spend an evening breathing in other people's smoke.

The truth is that everyone would gain from a smoking ban in the workplace. Everyone, that is, except the tobacco industry. No wonder they spend so much money trying to stop progress. But of course, they are the only industry making a product that kills you if you use it exactly as the manufacturer intended.

They spent decades covering up the evidence that tobacco kills smokers, now they are fighting a rearguard action to obscure the truth that it harms non-smokers as well. It's time to ignore the tobacco lobby's propaganda and legislate to protect the public, and particularly people at work, from secondhand smoke.

* Ian Willmore is public affairs manager for anti-smoking group, Action on Smoking and Health (ASH)