A lot of buildings are sealed up pretty tightly to save on heating and cooling. Sometimes the air for the building comes from not so good places. I remember working in one building where idling truck fumes would always come into the building and stay in there long after the truck would leave. (Not much you can do when you are held captive on hourly wage, lol.)

I hope there is a silver lining to all of this where working conditions will improve for a lot of folks.