I believe you are referring to those ones that look kind of like masks dentists use, correct?
Theres 2 main reasons.
1) The person wearing the mask is sick, and doesn't want to infect other people.
2) The person has Allergies, and they want to block out the allergens.
=]
Japanese masks are very colorful. These masks have a lot of red and gold on them. They are shiny and have ribbons hanging from them.
Japanese masks are inherently Japanese.
Japanese Samurai masks served as a type of facial armor. There were four types of Samurai masks, the Menpo, Hanbo, Happuri, and the Somen.
Most Japanese masks are made out of porcelain. It is because porcelain is a very shiny material.
Surgical masks are worn by Japanese people who are ill, so that they do not spread their germs to others around them.
Japanese masks are very colorful. These masks have a lot of red and gold on them. They are shiny and have ribbons hanging from them.
マスク Masuku
Japanese people wear masks in public when they are sick. It is considered courteous to do so for the sake of people around them.
Masks are generally exaggerated because they were once used in Japanese Kabuki theatre. The masks were used in theatre to display the emotions of the characters.
Masks were an integral part of ancient Greek tragedy, and possibly comedy as well. Half-masks were used in the Commedia dell'arte's improvised performances, the character was thought to be inherent in the mask. Japanese Noh plays use very intricate masks that appear to change expression when he angle of the head changes. Though they are not masks, elaborate make-up in Kabuki and Bejing Opera serves a similar purpose.
There are alot of different Japanese masks, they are called Noh masks and hanya is a type of them. If you type in Google 'Noh Masks' it comes with unlimited references and pictures. Enjoy!
They are made of Japanese cypress wood.