Some folks just have allergies - genetic predisposition, perhaps. It isn't that allergies were unknown before the 'modern' world, simply less common than they are now.
Yeah, I used to be gross when I was younger (biting my nails, nibbling on pens...), and it didn't prevent me from developing some of the worst allergies imaginable. I can't even eat 90% of food types lest I enter a pseudo-drunken allergic state of stupor.
Certain kinds of cigarette vapors make my ears and throat constrict in a matter of seconds.
