Its Valley Fever. It fungal, and can kill you. Geologists tend to get it because they tend to stir up dust. I was watching Northridge aftershocks on TV and was surprised at the elevations to which dust was being transported immediately after aftershocks. I later figured out that it was the extensive landsliding in the Santa Susana Mts. While I say "high", the visible dust may not have been high enough to nucleate rain, but it is an interesting idea. But, you have to have some graph or some statistics to back up what you say....
Chris