I think some people here are exaggerating how hard it would be to code, it could simply (and i use that word loosely) be another form of pressure, when it's low, nothing ignties, and so on. Like how ambient heat works on pressure. It would be hard, but not impossible... if somebody wants to try to code this, I give them my support.
Implying of course this would cause massive lag -.-
add it as an option like ambient heat and newt. gravity,[offtopic] and btw if you add oxygen environment you also need environment CO2, and maybe all gasses,[/offtopic]
you cant make fire where there is no O2(like when you try to make fire in CO2) and you'd also need an O2 view, with colors