Dude. That's literally what airplanes do. I don't know where people got the idea that the air in a cabin is "recycled". The air in an airplane will fully cycle

Dude. That's literally what airplanes do. I don't know where people got the idea that the air in a cabin is "recycled". The air in an airplane will fully cycle with fresh new air every 4 or 5 minutes to remove carbon dioxide build-up. The air you breathe on an airplane is the air that is compressed by the engines or the auxiliary power unit, cooled down by the A/C, and diverted to the cabin after passing through a HEPA filtering system. People get sick in planes simply because it's a freaking small tube with hundreds of people sharing the space for several hours. It wouldn't be different than putting the same amount of people on a ground facility with the same dimensions and good ventilation.