I am actually typing this from a sauna with less than ideal ventilation (slightly ajar glass door) - need to cut vent holes to the sauna/house walls but haven’t

I am actually typing this from a sauna with less than ideal ventilation (slightly ajar glass door) - need to cut vent holes to the sauna/house walls but haven’t gotten around to it - so the timing is good. The main use of the ventilation is to not end up with too high CO2 concentration