just an anecdote, lol--several years ago it was my first year being on planes a lot and I seemed to have bronchitis forever......I did buy a few masks and wore them because I was feeling really weak and just felt like I might have a relapse, plus I felt like it was the only fair thing to do...I got a few wierd looks but quite frankly I didnt care.....I dont expect anyone who is ill to cancel their flight because the airline charges so much, but I do think if you are visibly ill or coughing/sniffling that wearing a mask is a very kind thing to do...I wish they had them on the check in counters, maybe that would encourage more folks--it may not stop someone from getting sick but it stops the cough if you have one from flying everywhere. Now my immune system is incredibly robust