The air isn't breathable. you haven't been able to go outside in years.
Fortunately, your Mobile Habitat can go outsided for you.

Raid abandoned bunkers, recharge your vehicles core, use your resources to survive the regular hyperstorms where lightning falls like rain.

Driver Controls:
[W][A][S][D] - move
[Right Click] / [E] - interact
[Scroll Wheel] - Cycle equipped item on hotbar

EV Controls:
[W]/[S] - Accelerate/Reverse
[A]/[D] - Steer
[Space] - Hand brake/drift
[Right Click] / [E] - stop driving