@clintflint - That makes sense, since people are hardly breathing in whole cat hairs every time they get an allergic reaction.
It's kind of the same thing with a dust allergy. People aren't usually allergic to the dust itself. You're allergic to the spore of the dust mites that feed on the dust and dander.
I'm getting more and more allergic to dust as I get older, which is very annoying. Although, I'm kind of glad to have discovered this allergy, since when I was a teenager and not so good at vacuuming my room regularly, I used to feel sick before school every day. My mother used to joke that I was allergic to school, but I guess I was allergic to my own bad cleaning skills!