What I would like to do is to buy a simple CO2 detector.
It could very well explain some of the symptoms that we're feeling.
For example : being abnormally tired or exhausted
Regularly when I board planes as a passenger, in a full cabin, I will sleep very easily. Even if I had a completely full night of sleep and whatever the time of day.
As far as I know, they never check for CO or CO2 and even told the guys who bought CO2 detectors that their data was worthless because the device was uncertified.