a few feet of dirt and rock is pretty good shielding. On planets/moons with no/thin air living underground would seem to be the safest thing to do.

One other thing is odd.
Nitrogen.
Earth is the only major planet that has in it's atmosphere in any significant concentration. Every other planet either has none or very little. Then there' the . The moon Titan . Titan's atmosphere is thicker than earth's and has a LOT of nitrogen.