The question has implicitely a lot of variables attached to it:
- volume of the room
- how closed the room is
- size of the person (I'm 168cm long and 64 kg heavy)
That could probably be turned into some formula and I am interested in scientific insights.
But at the end of the day my question is actually of very practical nature. I have a small room - about 1m x 2m x 2.5m = 5m3 - and I would like to use it as super-quiet place for meditation, reading etc. - hence calm activities, no excessive moving around. To improve sound proofness I'll probably also increase the sealing of the door and there is no ventilation - no air exchange.
Now if I close the door - how long can I expect to stay there without the air quality deteriorating to a level where my mental processes start to be impaired by it?