Originally Posted by
PLeblond
I always understood that air inside an airplane was cleaner than most other indoor spaces. Very low risk of (airborne) transmission.
Example from source : "The air in the aircraft cabin comprises of around 50% fresh air from outside the aircraft and 50% of HEPA filtered air. The air in the cabin is also renewed 20-30 times an hour or once every 2-3 minutes."
The filtration isn't perfect and a recent systematic review of 15 studies shows that the risk increases with the length of the flight. However, wearing a mask pretty much negates the risk. Also risk varies with exposure time so taking your mask off to eat or drink increases the risk but it's still much lower than the risk of not being masked. You can get the study with details if you google "The Risk of Aircraft-Acquired SARS-CoV-2 Transmission during Commercial Flights: A Systematic Review" (I haven't posted enough to be able to post urls).