Japanese people wearing masks
It is a well-known fact in Japan, wearing surgical masks is quite common. We may have just discovered masks in Western countries because of swine flu, but it is not new in Japan.
There are actually many reasons. Lots of us think that Japanese people wear masks to protect themselves from high pollution or contamination because of the Fukushima nuclear disaster.
But this is not true. Japanese people actually wear masks to avoid spreading bacteria and viruses, whether they are sick or not. The possibility of contamination is actually high in Japan, because of the population density, especially in big cities like Tokyo and on public transports. Thus in Japan we often use masks to protect ourselves from bacteria. We also wear it to prevent exposure to dry and cold winds during winter or pollen when spring comes (many Japanese people are allergic to pollen).
Then having a part of the face hidden is not a problem in Japanese society. The mask is very popular: many producers sell several millions of masks every year!