Add delay to knock out gas (N2O) kicking in?

[According_tome]

c02 being invisible sucks, the whitish sleep gas is fine

It is silent killing gas but usally happens in places where plazma fire occured. You cant see it with blind eye but you cough beforehand. From time to time it also is used in pressurization chamber but when there is someone laid down sleeping and nothing else you already know whats going on. On the other hand you clearly can see no2 use scrubber and shield, problem solves itself. I remember co2 hurt you while you sleep but you wake up even without an intervention  but it has been a while since that happened but i remember you wake up after a while unlike no2.
Edit3: I forgot to add my point, I think both gasses are balanced, they have their strengths and weaknesses.