Well that's generally how heat exchangers work, for that reason, even in temperate climates.

I know there are some standards for recycling air in public buildings such as schools, and air born sickness seems like something they would have to worry about normally, so I would imagine they were pretty prepared for that aspect

I skimmed this but didn't really see much past the actual heat source https://www.cibsejournal.com/general/life-support-keeping-sc...