A displacement ventilation system was provided, it can form the "air layer" at the bottom of room so that resistance dewiness air meet directly the cold floor surface.
If you're healthy and have a quality ventilation system or a big kitchen, it may not be your biggest concern, though it will still impact the environment.
First, you should definitely be using a ventilation system while the gas is going, and a little while after, which a lot of people, including myself, don't do.
Not only that, the germ-infested gas cloud is less dense than the air around it, so it rises upwards right to where ventilation systems and other people's unsuspecting noses and mouths await.
When she finally did see action, one of her guns exploded and killed nine crewmen, and a further twelve suffocated when the ship's ventilation system failed in one of the turrets.
I would guess that it could be part of the ventilation system—you see, there is a metal door that can be closed to keep out the cold air—but it doesn't seem to be connected to the outside.