[magduf]

Surgical masks don't need to offer complete protection. For one thing, something is better than nothing. But more importantly, the reason people in Asia wear these masks isn't really to protect themselves from getting sick, it's to protect everyone else from getting sick from them. It's a product of a culture that values acting in the interest of the group instead of only in your own selfish self-interest.

So it's sorta like "herd immunity": if everyone is wearing a mask to keep everyone else from catching whatever they might have, it makes it much harder for diseases to spread around and everyone benefits.