A couple years back, someone made reference to a fellow who was developing a respirator based on a snorkel mouthpiece with tubes that went around the neck, and rested on the shoulders. The tubes ends were fitted with dust filter discs. The product is now on the market, at around 50 bucks. The problem is it does not accomodate organic cartridges. Soooooooo.......,
I took one of my 3M dual cartridge dust masks, my seldom-used snorkel (Montana snorkeling???????), a bit of 1" flexible hose, and converted the respirator into an on-the-back unit that is connected via the snorkel to moi. The snorkel has a purge valve below the mouthpiece, so exhaled air goes directly out and not back into the filters or tube. The flexi hose is connected to the exhale port on front of the respirator, so when you inhale, the valve opens, when exhaling it closes, which serves to help the purge valve at the mouthpiece open with very little exhalation pressure. The face opening of the respirator is covered with heat-shrink window film, and backed up with some of that stretchy-plastic stuff the lumber yard uses to bind your stack of goodies together.
The face mask is clipped onto the back of an over-the-shoulder camera strap, kind of like a mesh pair of backpack straps. It works surprisingly well, is easy to spit the mouthpiece outwhen you need to talk, and provides a 100% seal, if you made all your connections tight. After two years of wearing a gotee, I now have a full beard again!!!! My wife is very happy (I hate to shave, and my normal state came to resemble 60 grit paper). Looks a little funky, but....

I also considered using my dive mask as safety goggles when using the table saw, but I'm afraid the UPS man might never show up again