Originally Posted by
nliving
While a shortage of O2 would be a critical event, might I also suggest an increase of CO2 as an equally important factor. Thank you.
Not really. The lack of O2 happens due to the low atmospheric pressure after a depressurization, not due to passengers consuming all the oxygen. CO2 would take many hours to accumulate to dangerous levels, and since the plane is no longer airtight, it would be simply vented out.