At the end of the Seventies, the anti-smokers first seriously turned their attention to what they called "passive smoking". Over the next decade, it is fascinating to follow how, try as they might, they could not come up with the evidence they wanted to prove that "environmental tobacco smoke" was directly harming non-smokers' health. They became greatly excited by a series of studies which purported to show a link between smoking and cot deaths. But these somehow managed to ignore the fact that, in the very years when cot deaths were rising by 500 per cent, the incidence of smoking had halved.

A further series of studies in the Nineties, mainly in the US, claimed to have found that passive smoking was causing thousands of deaths a year. But however much the researchers tried to manipulate the evidence, none could come up with an increased risk of cancer that, by the strict rules of epidemiology, was "statistically significant".

In 1998 and 2003 came the results of by far the biggest studies of passive smoking ever carried out. One was conducted by the International Agency for Research on Cancer, part of the World Health Organisation. The other, run by Prof James Enstrom and Geoffrey Kabat for the American Cancer Society, was a mammoth 40-year-long study of 35,000 non-smokers living with smokers. In each case, when the sponsors saw the results they were horrified. The evidence inescapably showed that passive smoking posed no significant risk. This confirmed Sir Richard Doll's own comment in 2001: "The effects of other people's smoking in my presence is so small it doesn't worry me".

In each case, the sponsors tried to suppress the results, which were only with difficulty made public (the fact that Enstrom and Kabat, both non-smokers, could only get their results published with help from the tobacco industry was inevitably used to discredit them, even though all their research had been financed by the anti-tobacco cancer charity).

In the early years of this decade, the anti-smokers had become so carried away by the rightness of their cause that they no longer worried about finding disciplined evidence for their statistical claims. One notorious but widely-quoted study commissioned by 33 councils campaigning for a "smoke-free London" came up with the wonderfully precise claim that 617 Britons die each year from passive smoking in the workplace. No longer was there any pretence at serious debate. This was a propaganda war, in which statistics could be manufactured at will. (The European Commission's 2006 figure for annual deaths from passive smoking in the UK was around 12,000, some 20 times higher than the figure quoted by the British Government itself.)

By the time the Commons pushed through the smoking ban in February 2006, a kind of collective hysteria had taken over. MPs fell over themselves in boasting how many lives they were about to save. One Department of Health official was quoted as equating its significance to the Act setting up the National Health Service in 1948.

As clouds of self-righteousness billow out over England this weekend, the anti-smokers may be entitled to give us their view that smoking is a thoroughly noxious and nasty habit, even that it can exacerbate respiratory conditions such as asthma or bronchitis arising from other causes. They can even claim that the ban will save lives by persuading smokers to give up. But the one thing they cannot claim is any reliable evidence for their belief that passive smoking is responsible for killing people. Sir Richard Doll was right. It is merely a sanctimonious act of faith.

http://www.telegraph.co.uk/news/main.jhtml...01/nbook101.xml