Tokyo Suburbs

Bicycles are a popular mode of transportation in outer Tokyo. And even in this city, I saw people wearing face masks.

Like Hong Kong and other Asian countries, people wear masks not because they don't want to breath in pollution (though that may be part of it), but because they're sick and don't want to spread their germs. Asians are very conscientious that way; at least, they are now, since the SARS epidemic has taught many that public spitting is a bad thing.