I understand that tobacco used to be a lot worse before they started experimenting with "Clean Tobacco" back in the 1930's. My grandparents told me how you couldn't go into some buildings because they stank so bad. Today, it's really hard to tell when someone lights up, such as a fellow passenger on the airplane, or a child in the classroom. It just smells like whatever artificial scents they put into the tobacco, if any.
The other issue was the discovery of the wonder drug unobtainamine back in the 1950's. A universally efficacious treatment for all allergies, without any side effects whatsoever, is the only thing that allows many people to happily smoke alongside their peers without having horrible, even deadly, reactions. It also helps people who are only mildly irritated by the smoke to be a lot more comfortable.
Although, I imagine if the Federal government took a more proactive role on things seen as "public health risks", there might be some minimal legislation against smoking in certain public places. Of course, this would also probably lead to putting safety belts in cars -- or even declaring laws which require them to drive in an organized manner -- making people wear helmets on motorcycles, and requiring the apothecaries and chirurgeons to have licenses.
I would imagine that they'd probably have government bureaucracies instituted to study things like how many people die of different things per year, so they could know how effective those laws were.