Fear of getting sick :c
I used to have to bus 1 to 2 times a day, one way would be 45 minutes to an hour. People would always be richards and sneeze into the air, not even realizing what they were doing; almost all of them had colds and would be coughing too.
I'd get really bad colds every 2 to 3 weeks because of these people. Moment I stopped taking the buses, haven't been ill for several months.