I think people confuse second hand smoke with smelling a cigarette.
I can understand a smoking ban in someplace where a non-smoker has to stay for a while, like an eating area. Or a smoking area next to a work area.
However, walking by the smoking section and smelling a cigarette - if you think this is going to give you cancer then you should be more concerned about your mental health. And I got bad news for you - you're being exposed to all kinds of things you don't even know about. At least you can smell the cigarette. Now go worry about that.