well ya, but there are some people out there that are very allergic to smoke from cigarettes and they cannot be in a room that smells of smoke. or around people that smell of smoke.
True, but the severity and quantity of allergic people still doesn't necessitate the move to a ban. I'm allergic to all nuts, and even I get a bit queasy when talking to someone who just ate some peanuts or almonds. I wouldn't have them ban the legume just because of my allergy. It's up to me to find a way to keep a safe distance.
Now I'm not sure on the radius of standing from a smoker, but an easy solution is to crack the window open a bit. Make sure the smoker smokes outside and stays out for a few minutes before coming back in. Hang up your jacket in the closet or in another room that is well ventilated. There are so many solutions to a problem that doesn't need government intervention.