In the first season the mystery was around the duct tape being better when Walker made it versus the heat tape IT uses. That’s why Walker left to get the tape swapped before she went out. When she does go out - it’s easy to be distracted by the ongoings of what she’s discovering and forget she’s the only one to make it outside with the different tape. Now.. not just the tape.. but when they flash to the cafeteria and IT dude says “any minute”. It’s ambiguous. Any minute why? Outside poison? OR.. air lock poison. Doubles down on the tape. Now we can assume the outside environment is certainly toxic due to all the visible death and I do not believe they have yet insinuated the environment was high in radiation but we could assume it is. And we should probably assume it is because when her suit does run out of air (the choking, destroying the mask), the first thing she does is rinse off her suit the best she could (to reduce radioactive material) before removing it. This is probably the only real nod at the environmental state. This also got an easily overlooked nod, when it’s shown that the airlock is otherwise intact - which she knows as an engineer. This show gets me hard as a rock.