I used to stand at a bus stop in Jakarta where, the air was really nasty, and I kept getting cold after cold. I had thought of colds as a winter thing before I went there, but pollution seemed to make me vulnerable. Then, I started taking 500 or 1000 mg vitamin C tablets and I stopped getting colds. I'd like to see a study that tests vitamin C as prevention for getting colds while being exposed to polluted air, in addition to the athletic and arctic training conditions.It seems like if vitamin C helps after you already get a cold, its just incremental. The study mentioned in livescience was along those lines, that it could shorten the duration of a cold by a day. The Chinese video and Indonesian news clip about the IPB findings both seemed to overly optimistic