One thing is to learn from what happened. Sanding dust will migrate
everywhere, period. You have to collect it at the source, like with
shop-vac and gore-tex filter connected to sander.
A vac with that sort of filter will help collect the debris now, but
it's a much bigger project, obviously. Back when, I noticed such fine
dust settling 15-20 feet from the source, indoors, in "still" air.
Dust particles above about 1 micron don't make it to your lungs;
smaller than that down to about .25 micron get there and stay,
according to USCG studies.