I did notice when I lived in an apt, middle floor I didn't get so much dust. I live off a dirt road now so the dust is constant. I have dogs too so I have that hair factor. I have a room though that I rarely go in, sort of just for bookcases and some boxes and it's super dusty. It's on the back of the house facing some land so dunno what the deal is.
Old houses do get more dust let in than newer unshifted ones
2c/3a?
Low porosity, medium texture.
http://public.fotki.com/Medusahair/

If it smells good put it in your hair, if it tastes good spit it out!