Yes there are most certainly horrible circumstances like these, I am no scientist, but im pretty sure that being in those environments might just kill you from exposure alone, gasmask wouldnt matter. Especially considering a lot of players in cataclysm run around in baggy (military or cargo) pants and trenchcoats.
Fact is there arent a lot of these; poisonous caves and smokers (correct me if i’m forgetting something where you absolutely have to have a gasmask if you want to live) are areas where gasmasks are a definite plus, but before you make the gasmask filters have a durability it might be practical to first design the game in a way that supports that.
I.E.:
-Hazardous hotspots or even gasclouds that move around
-Different tiers of equipment whereas higher tier means more effectiveness/durability (homemade, consumer-grade, industrial-grade, military-grade)
-craftable (homemade) filters
-retcon the current “lore” to match up with metro, because thats where this is coming from
Otherwise changing filters every 5 minutes while running through perfectly fine suburbs would make utterly no sense at all, instead it would be a nuisance. Modern GM filters last from 20 minutes to several hours depending on hazardous agent, composition, density, air humidity and of course GM quality.