I got a good quality respirator at Home Depot... they have a number of different types. I got the one the filtered out the most... toxic dusts, pesticides, etc. When I mix some real foul smelling stuff with it, like Bondo, I can't even smell it! It has replaceable filters and an exhale valve... much more comfortable and practical than the disposable dust masks. I use it for spraying acrylic paints, cutting PVC (for my SPADs), etc.

I also bought a 20" box fan and a 20" 3M Filtrete AC air filter and taped to to the back of the fan. I turn this on full blast (filter side towards my work area) when I'm cutting or painting... it sucks most of the dust & overspray into the filter...