I don't think banning smoking would work, firstly.
The problem I have with it is that I find it uncomfortable to experience second-hand smoke, it makes me feel sicker than if I actually smoked first-handedly. I often can't choose not to experience it, it comes from people walking in front of me in the same direction. But, if you take smoking off the streets, you put it directly into homes which has other problems. It could potentially be worse for children who have parents who smoke. While most parents would go outside or smoke out the window or something, not all do. This seems to be related to health issues in children, particularly asthma. To some extent, smoking does impose upon other people's rights to breathe relatively clean air.
Furthermore, those bien-pensant anti-smoking campaigners seem insufferably paternalistic, thinking they know what's best for others. I'm sure that the people I know who smoke a lot, if quizzed about their attitudes to the risks involved, would say something like: "I'd rather live my life the way I see fit and risk dying earlier, than have my life circumscribed by the precautionary principle."
I think that's true, at least to some extent. For that reason, I don't like anti-smoking campaigns. Aside from the fact that they don't work, I think that they are guilt-inducing and victim-blaming. I think some people smoke as a life long coping mechanism, particularly for people who are alienated or who were alienated when they became addicted to cigarettes, and without it they might suffer immensely. There are very many social conditions and personal circumstances that cause smoking (people don't just start because they think it's cool or because they don't know the risks, I mean, how couldn't they know the risks? And how many other groups of people are as seemingly legitimately and incredibly ostracised and condemned as smokers?) and I think we'd do well to try and understand those rather than just dissmiss it as being inappropriate and wrong and banning something that is a source of comfort and pleasure, albeit a very damaging one.