[pops88]

"The problem may be aggravated by the growing use of recirculated air, a fuel-saving measure that may increase the potential for disease transmission in the cabin."

As a pilot and a nurse, this is one of the things that for years has bothered me about flying commercially. Some planes can use 100% outside air, but many have no option but to use recirculated air. They weren't designed or built for a choice.

[aristeides]

If the air has to be recirculated, is there a way to filter it?