Just two years ago it would never have occurred to me when visiting someone to ask if it was all right to smoke. From about a year ago, this question was becoming mandatory (though as an exercise in politeness it doesn't really work - what could an anti-smoking but polite host reply except a pained yes? Then again, if the duty of a host is to make their guest feel at home, and that of a guest is to remember that they are not, the guest should not ask.)

I remember enjoying a cigarette in my local Seattle Coffee Company before being astonished at the lack of commercial competitiveness when Starbucks took them over and prohibited smoking (they must lose a lot of punters to Caffé Nero, who allow it). Subsequently, I have been amazed how few cafes still permit it - for smokers, what's the point of a coffee without a fag?

What fascinates me is the speed with which we became social pariahs. I am not proud of smoking, but nor am I ashamed of it. Yet to judge from some reactions I am pathetically lacking in self-restraint and shockingly antisocial. People look at me as if I am injecting heroin into my arm in front of them (in fact, that might be healthier; a recent study in the British Journal of Health Psychology showed many heroin-users may live otherwise normal lives, with no pathological consequences). There is the added implication that I might be killing them (though there's no evidence that occasional passive smoking is harmful).

The anti-smoking groundswell seems to have come from nowhere. Why didn't it occur in 2000 or 1996 or 1986? Social science is lousy at explaining such cultural shifts, yet many of the most important ones seem to have no legislative origin. Feminism was arguably the most significant single change of the past century. It's not easy to explain why that happened after the Second World War rather than after the First, or even the Boer War.

A clue to the smokophobia is that it's not global. Travelling last year (courtesy of the British Council, writing a book), fagging it in New Zealand, Australia, Singapore and America was even harder than here. But in China and Russia there was no problem, and in Denmark it was mostly accepted.

It happens that the governments of the post-colonial nations also share the pious, sanctimonious mentality of their leaders, Bush and Reverend Blair. Since so many of us abhor them, it's hard to believe their holier-than-thouness is catching. But if I'm wrong, how long before alcohol gets the same bad name as smoking?

It's well established that living with a heavy drinker is bad for their family's mental health (passive drinking?). Perhaps 'new evidence' will show that the outgoingness and assertiveness of social drinkers is harmful to someone who is sober.

Who knows, when out for supper in two years' time, you may have to ask if it's all right to have a glass of wine from the bottle you brought for your own consumption. Other diners will look on askance as you kill yourself, and ruin their evening and health with your boisterousness.