Although I have a full beard, I use a North respirator. Works
reasonable well, as I have it snugged up pretty tight. If I use it I
don't have much problem with reactions to sawdust, and I notice that
the wood smell grows markedly stronger immediately when I take it off,
thus it is filtering a fair amount of dust.
I also use it when I spray-paint the house with oil-based paint. THEN
I shave and use organic vapor canisters.
Obviously, if you are having very strong reactions to sawdust you
either need to shave and use a "Darth Vader" mask like the North, or
get a pressurized mask.
Wearing masks is inconvenient, but it makes life much more bearable and
lets me continue with my hobby. I also have a CPAP machine, which is
also inconvenient to wear, but boy do I sleep better at night!