The college where I teach is actually considering getting air purifiers for the rooms. They are currently in the process of getting student feedback, as well as feedback from the staff and instructors. It is an interesting approach, considering high efficiency air purifier.
The feeling is that with some many different students in the class, some are pretty full, some people have allergies, it would be a small cost to benefit the entire population. I am not sure how it will work but if it will keep fewer germs from getting in the air and will keep the students healthier, hopefully resulting in better attendance, it would seem to be a smart move.
Teaching as an adjunct can be a lot of fun. It is also challenging. As I have encountered a number of situations, I realize such a blog can be helpful, both to me and to others.