The dry air in airplanes is not circulated. The cabin is pressurized with air from the compressor stage of the jet engine. Pressure is regulated by letting some

The dry air in airplanes is not circulated. The cabin is pressurized with air from the compressor stage of the jet engine. Pressure is regulated by letting some air out of the cabin. It feels stale because the rate of air replacement is not fast enough. I agree with all your other dislikes of air travel though :) I wish we had more high-speed rail in the USA. https://en.wikipedia.org/wiki/Cabin_pressurization#Mechanics https://en.wikipedia.org/wiki/Cabin_pressurization#Mechanics