Before the pandemic, wearing masks is a norm in Japan, even at fashion shows. Before epidemic, China’s celebrities always wear black masks to hide themselves from the public and paparazzi.
But in the West, masks seem to be used to protect others. They are often worn by people with a cold or flu to protect others, not the wearer themselves. The same is true of masks worn by dentists and surgeons, for example, which are designed to prevent the wearer from spreading germs to patients.
Masks can also be effective in protecting the wearer from airborne particle.