Many of the Japanese wear masks when they get a cold. If I am ordered to make an illustration of a person having a cold, I would draw a mask made of white cloth on his face. Because it represents a cold. People put on masks when they feel they have a cold....I thought it as a matter of course. But one day my colleage from England told me that it is a custom peculiar to Japan. He said it was useless for avoiding virus in and out. Yes, that's right, and I knew that. Not only myself, I guess many of people wearing masks should know it is practically useless....Then, why we do that? Wearing masks has two main effects :- 1. He can inform others he is having a cold without any explanation. 2. He can inform others he is a person of thoughtfulness who tries his best not to give others his cold.