Wouldn't everyone be allergic to dust because there is always dust everywhere?
Well, I'm not sure that more exposition necessarily means more chance of being allergic to it, otherwise we'd all be allergic to milk by the time we're 5 years old.
I'm allergic to house dust too. Whenever I do any vaccuum cleaning or stir up some dusty things (like looking from something in some old boxes or closet), I quickly get a stuffy nose, watery eyes and sneeze repeatedly for a couple of hours. Really annoying. Keeping the house clean means being afflicted by this every other day, but not stirring up any dust means leaving the dust on the ground / tables / shelves / everywhere. Damned if I do, damned if I don't.
what are you guys allergic to?
I've been to the hospital once as a teenager with a moderate case of allergy (not acute or life-threatning), but we could never pin-point what it was that caused it, and I never had the same thing since, but it was definitely a allergic reaction. So, I guess I'm allergic to something, I just don't know what.