That works! I played for about 30 mins with headphones on. I'm not sold on the respirator mechanic - I think picking up oxygen supplies instead of remembering to use the respirator every so often would be more interesting.
The overall concept is nice though. My favourite thing about this game is how atmospheric it is, which is pretty impressive given the amount of greyboxing. I had a little "wow" moment when I was walking across a bridge and there was a crack of thunder. The combination of the weather effects, water running down some of the angled surfaces, the fog, etc is pretty effective and I can easily imagine how the game might look with finished art. Good job!