Okay, have an idea about this story called Gas Mask, and I know this may be more suited for a research thread, if there is one, but please I need help in two areas. A. Okay, how long can someone wear a gas mask before they have to take it off? This is important because I'm thinking of a story where someone may have to spend multiple days outside in an enviroment polluted with deadly chemical weapons. B. Are there any normal building that are sealed against chemical weapons? If not, how would one perhaps go about sealing a building against chemical weapons? I mean, the character has to be able to take it off sometimes.