I saw a few of discussions relates to the use of dust mask. Have you guys heard of TOTOBOBO mask? It is a new type of reusable mask. It's transparent so you can check the seal visually. Lightweight and doesn't interfere goggles or glasses. Anti-virus and can be trim to fit almost everybody. The filter contains electro-static charges and is able to capture very fine particles (94% efficiency for 0.3 u). Most importantly, almost everyone tried it said it's very comfortable to wear.
Some user testimonials (go to the bottom of page):