Yesterday and the day before I voluntarily put on my mask. It's a N95 drywall mask. 

I picked this thing up on Amazon back in December for occasions such as this. It's hand-washable and has removable filter liners. It fits snugly because it has velcro straps instead of elastic.

If I'm cutting small holes for a box or making small trenches in walls, I typically don't wear it. The days in question, however, I was using a 6" hole saw. They create a lot of dust at one time. Dust was like fog in the air.

My shirt was black when the day started.