I think where it can be differentiated from the examples Sean gives is that, without a doubt,
passive smoking can have a palpable effect on the health of people who do not, themselves, smoke but who are around cigarette smoke all the time.
The case we always think about in the UK is that of an entertainer called
Roy Castle who spent a good deal of his younger life doing the jazz club circuit, and who died of lung cancer even though he was a non-smoker himself.
With most other habits or lifestyle choices, the direct effect on health is only self-inflicted. (Unless you count the people who get the shit kicked out of them on a Saturday night by a drunken yob, of course. )
I still think it is wrong to try and force people to stop smoking, if that is their choice. But I think it is right to ban it in enclosed public places, such as pubs, bars, restaurants, clubs etc. I have found it much easier to stick to my non-smoking nicotine habit since smoking has been banned in pubs here. Whereas before, after a few drinks with friends, I would be happily stealing their cigs from them, nowadays I am happy to stay in the pub while the smokers go outside in the cold and rain and feed their habit, while I continue to feed mine with the Niquitins
