That's why smoking is already heavily regulated in order to limit and minimise the impact that your choice has on others.
You can smoke as much as you want but smoking in public places, especially indoor, is banned not to impose your health choices on others.
This is how liberty works in a free society as mentioned in my previous comment.
Banning smoking altogether, on the other hand, is deciding for you and exactly what the "nanny state" refers to.
The claim that "it impacts others" is, at very minimum, exaggerated, but just as often completely fabricated out of pseudoscience and absurd movie plots.
Smoking is heavily regulated because there was a resurgence of teetotaling in the late 20th century.
Personally - aside from the smell - I have no concerns about people smoking near me outdoors or even in very well ventilated areas. I understand though that for some people (such as asthmatics) it can be a real problem that goes beyond simply being unpleasant.
Somebody probably drops a spent match, it's still smouldering and it drops inside the escalator where it finds plenty of fuel and begins a fire. From there you mostly just need bad luck - yes the staff could be better trained, but even when they do summon professionals the firefighters don't arrive in time to tackle it while it's still small, the then-unknown trench effect allows the hot gases to pool and initiate flash over suddenly, a bunch of people die.
