Yeah, I don't really know how to solve that problem.
Heavily considering adding a beep that beeps faster depending on oxygen level, but we all know how people feel about beeps.
There's already a beep in the game right now but it's very subtle, I'm talking *almost* a "The Legend of Zelda: A Link to the Past" low health situation for the new beep.
And there's also the fact that oxygen has not really been implemented how I want it yet, so expect there to be less oxygen drain overall and more specific rooms with heavy oxygen drain in the future.
Except for the no-suit part of the game, that will probably not change that much.