Unfortunately, I don’t think there has been research here.
Hopefully since the start of COVID (it is not over) any new builds or upgrades will include fresh air and filters. This is already done for large gatherings of national leaders so the tech is available.
Perhaps dust and particulates? The SoCal area is very dusty. If you leave your car parked for a few days it will have a fine layer of dust on it.
Imagine breathing that in along with all the other germs normally present in a classroom. Less sickness should allow more learning.
I would assume it’s the last point; less sickness from airborne illnesses means more time and energy for learning.
Unfortunately, I don’t think there has been research here.
Hopefully since the start of COVID (it is not over) any new builds or upgrades will include fresh air and filters. This is already done for large gatherings of national leaders so the tech is available.