people with colds wear those surgical masks in the city, because japan is so crowded. colds would spread like wildfire in the subway or the busy streets of tokyo, and you probably know already that japanese show alot of respect for one another, as apposed to america where we don't give a shit if people near us get sick or not.
"Why do so many Japanese people wear face masks in Japan?
some Japanese are being courteous when they have a cold and wear the mask so they don't breathe their germs on you and infect you too"