Some of this is experiential, but I know at least some of it is in my head. I remember reading a scifi story that included, just as a sort of throw-off scene, a dramatic demonstration of the need for positive air circulation in space. The theory is that even when there is enough oxygen in the air, the pocket of carbon dioxide you exhale stays around you and grows and keeps the oxygen out. Something about hot air not rising in free fall?? I remember the idea was presented as a prank to scare a newbie: one would light a match and watch it extinguish, then claim oh no! low oxygen levels! After the newbie panics a little, then the science would be brought out.
I integrated the scene into somehow always feeling hotter and hotter when I sit still without a fan blowing on me. Ok, so sometimes I'm actually getting hotter. whatever.
Northern Europeans have such tight-built homes with radiant instead of forced air heating, that stale air is a common concern. Thus the habit of open windows even in the dead of winter.
All of this feels more psychological than real to me. Especially my mom never letting me or my brother fall asleep in "the bomb." When we lived in Iceland, we bought a used car from a departing serviceman, one in a long line of sales. There were holes in the floorboards, and maybe in the exhaust system? (Probably responsible for the nickname.)
Anyway, mom was convinced that if we fell asleep in the car, then we would die of carbon monoxide poisoning. We had to keep the windows cracked and stay awake anytime we were riding in the bomb. I'm pretty sure the fresh air from the windows was the important factor, not our consciousness state.
We now return you to much more entertaining reading in the Real LJ Idol.