>>2459977to protect from dust/asbestos inside crumbling buildings and toxic fumes too. there's places in the area i regularly explore which seem to be near a chemical dump or some kind of pool of toxic waste, whatever it is, if you breathe nearby, it makes you fucking choke without a mask. There's another area where if the rain leeches chemicals out of the abandoned area nearby, and there happens to be little to no wind, the gasses coalesce in this one point in the small valley I have to pass through to get there and I'm really glad of my mask then. Have to walk more than 200 feet before it clears up again.