> > Cigarette smoke feels like it sucks the air out of a nonsmoker's lungs from quite a wide radius [...] makes people involuntarily gag

> Unless you have an allergy or something, this is entirely in your head.

The fraction of the population with asthma is easily high enough that there's plenty of people for whom it's not in the head.

Personally I just hold my breath and speed up until I've passed those people, but its most definitely unpleasant.