In an effort to make my position slightly clearer: I have no objection to people doing whatever they want in the privacy of their own homes. But I don't see why smoking in public places (particularly in crowded public places) is any better than walking around punching people - both involve knowingly doing harm to those around you for your own pleasure. That's acceptable (IMO) if and only if the other people have consented to it (and there is a case for special smoking-allowed pubs on those grounds).