Similar things happen in the country, but it's dust from gravel roads, and/or from farming (discers, plows, combines, and so on). House can be 100 meters from the road and you still get tons of gravel road dust. Though, perhaps, that's not as bad for you as brake dust. In some corn towns it "snows" crap from the processing plants for part of the year. Can't imagine that's good for the lungs.

Same here— in the east bay (Milpitas). I was alarmed by how much silt built up on any outdoor surface. I assumed it was due to nearby highways and busy roads. Left that living situation after 2-3 months due to the concern.

Wow. Did you feel any ill effects? Did you recover when you moved?