Here is the full list of all 7 Low Oxygen achievements.
Enter the lush caverns of the facility.
Find the blue key up high outside the facility.
01101000 01100101 01100101 01101100 01101111
Find the yellow key near the crashsite.
Find the red key somewhere under a ceiling lamp.
Find the white key near a lot of ladders.
Find the black key near the rocket.