Fwiw. I'm one of those with an extreme, uncontrollable reaction (luckily temporary) to fag smoke and a couple of other smells.
Recently added instant coffee, OH's deodorant, and ribena to that list.
I would not allow smoking in my back garden or house. In that scenario it's either I leave, or the smoker leaves. Which I know I've already said.
However, what seems to have been assumed about people like me with strong anti smoke reactions and feelings - is that I would try and impress my will on other people.
It's not true. If sitting outside at a pub or restaurant, I recognise completely that people will probably smoke, and therefore I move or don't sit there. If someone is smoking in front of me on the pavement, I would move (crossover), or otherwise take myself away from it etc. If invited somewhere I know there will be a lot of smoke, I will either politely decline, or take steps to remove myself from the smoking person. Because it's not my home.
But when it is - that's the one place I don't think I should feel bad about it.
I will say that I despise having to enter asda, or my hospital, etc etc through a fug of smoke, but there is no other choice. I wish they would bring back smoking shelters at an appropriate distance and enforce them.
This was especially awful when leaving hospital after a stillbirth and walking through a group of pregnant women smoking, or taking a premature baby born with breathing difficulties into the hospital through similar clouds. Things like this can colour how one feels about smokers as a group, though I do my best not to let it.