It occurred to me as well but I just assumed that some provision had been made for air. You could run pipes to natural vents in the earth underground with natural air flow and provide enough air exchange for a small area. For that matter if you had a self maintaining plant room, it can provide enough oxygen. Read up on Biosphere 2 which was completely self contained and this wiki article talks some about the use of plants in spaceship and space station design: http://en.wikipedia.org/wiki/Life_support_system
Whats cool about that system is that the only waste is CH4 which is methane and heat. SInce you have a constant temperature 50 feet below ground, you don’t need the extra heat and a pipe and fan can move it a good distance away into a cavern or better yet if there is a lake nearby, into the bottom of the lake where it will be either absorbed or bubble up to the surface. The best part here is that the living quarters would appear to be a small thermal vent on a deep ground scanner if it is detected at all.
I had a little weirdness with it this morning due to the pagespeed caching on the site. Hopefully, things have resolved for you….I know can see the comic right now…although I couldn’t for a few minutes this morning.
I did more than a bit of research on biospheres…and as for the rest I saw the same article you mentioned.
Heh, that’s the same I article I used to come up with how Keighvin was powering and setting the place up.
I had a little weirdness with it this morning due to the pagespeed caching on the site. Hopefully, things have resolved for you….I know can see the comic right now…although I couldn’t for a few minutes this morning.