Jeff, you can skip the mask, just keep the exhaust going with CA. Masks filter organic vapors, CA is the from a family of isocyanates, same as expandable foam or urethan resin. There's no respirator that filters it (they've been researching for decades). The closest thing is using a wet filter pad which binds the iso before it gets to bind with your lung moisture.

If you're experiencing tightness in your nose and throat when using CA, that's what's happening. People get sensitized over time, so it may not bother you for years of use, then all of a sudden it does.

Not writing to scare you, just to let you know there's no need to put of a respirator. Pulling air past it and away is enough in the small levels in CA and it'll readily bond with atmospheric moisture. I have a friend who spilled it in a lab, left it for the hazmat crew. By the time they cleaned it up, a specimen aquarium in the lab had a solid plastic crust on the surface.

Solvents like lacquer thinner attack the brain, liver, etc, the same as alcohol but on a much more dangerous level. Isocyanates don't, they just bond with moisture and crystallize. The problem arises when that crystallization is in your lungs.

I have a powerful booth set up to keep me out of the airstream when casting resin, but with measuring and stuff, I occasionally get close to it. If I'm doing a lot of production, running the molds on the hour, I'll start getting the tightness in my sinuses by the end of the day.