Alien Sector
You have decided to travel to Green 23 in the Alien Sector. This is several levels below ground, where the corridors are lit by a strange light reminiscent of sodium, sulphur or methane. You come to a doorway that is sealed. It has a symbol displayed on it representing a breather mask. This reminds you that you are about to enter an alternative atmosphere zone, so you may need an oxygen breather mask...
Breather Mask
As you go through the first sealed doorway, you notice an alcove to the side. The protective glass slides up, and you can pick from several different breather masks, which have red, green or brown gas bottles attached.
You know that the one you want is the mask with the red gas bottles, which contain pressurised O2. Picking this up, you press it against your face, finding that it fits snugly around your forehead, temples and jawline, making an atmospheric seal. However, it is still flexible enough so that you could speak:
"Ambassador Kosh, may I see you"?