The escape hoods I've seen are probably the best thing to have due to their CO2 protection. I carry a pair of ski goggles and dust mask in my backpack that goes most places with me. Be careful of scuba masks. They seem like a good idea being sealed and all, but if you don't put defog in them they'll steam up when you start to sweat, and if I ever have to use mine, I can assure you that I WILL be sweating. GI sun/wind/dust goggles would probably work, but I have no experience with these. The respirator I carry I picked up at Home Depot last summer. It's paper, similar to those worn by medical personel, but thicker and it is actually a harmful dust respirator. It's made by 3M, model N 95. I know it's not the best solution, but it folds inside the goggles, so it doesn't take up any more room, which means I'm much more likely to have it (not to mention the price is much easier on a college student's budget). Looking on their website, it seems HD actually has a mask that supercedes the protection of the one I have. I don't recall seing these in the store, so maybe I'll check that out. If I do I'll be sure to report back.
I'm sure different things will work better for different people, but I feel that this one will work for me, but hopefully it'll never have to.

Chris.

PS-- I can't get the link to behave, but if you go to Home Depot's main site and do a search on respirators, it should give you both the mask I have and the one that seems to be a little better.