Space suits have oxygen storage ratings up to 6 which represent how much breathable oxygen they contain.
A space suit takes 1 turn to fill while in a breathable pressurized environment, or instantly by using an oxygen tank (1 burden slot).
When relying on your suit to breath, consume 1 oxygen per turn.
When suffering damage to your suit, the suit loses oxygen for each point of damage taken. Suits self-repair (preventing further leaking).
If you run out of oxygen or cannot breathe for whatever reason, you immediately panic (without a saving throw), meaning you go to 0 Guard and all your attacks are impaired.
While without oxygen, you suffer 1 Strength damage per round until you reach a breathable environment.
You can hold your breath to avoid the effects of running out of oxygen by adding 1 Fatigue to your burden per round.