I don't mean to be rude but in effect - if I understand you correctly - your solution to the problem that I am being forced to inhale chemicals against my will is to force me to inhale even more chemicals to make up for some of the damage caused by the first chemicals while at the same time making me take the bad side effects from the second set of chemicals? Taking medication against it sounds good but the medication comes with side effects as well such as temporary full body palsy (shaking - and incredibly uncomfortable but at least you can breathe I guess) and blisters in the mouth for instance which makes them pretty unattractive if at all avoidable.
As for the train stations, I would love that but the problem is that the designated area is called "outside". In Denmark, smokers have the unfortunate habit of spreading out all over the stations 10 meters apart, ignoring the indoor smoking ban and insisting on getting those few last precious inhalations, packed in the cue to the train doors. And the same goes for busses, shopping streets, parks etc etc etc.
My wife works at a hospital and when I go to pick her up, its very common for 10-20 smokers to stand just outside the door, ignoring all "no-smoking on the premise" signs, while people with oxygen tanks and breathing masks try and find a way in because the smokers damn sure wont budge.
But yeah, on topic, cannabis is pretty much the same as smoking cigarettes from an asthmatics point of view. I definitely support the model that Holland uses with smoking bars though. It would be lovely to have such places because I honestly think that people should be allowed to smoke if it could be done in a way which does not affect others - freedom of choice should be universal as long as it does not limit other peoples choice (as smoking anywhere unfortunately does)