You don't even need to wear a N95 mask, or wear it according to the book. Anything that can reduce the number of virus particles you are exposed to when someone

You don't even need to wear a N95 mask, or wear it according to the book. Anything that can reduce the number of virus particles you are exposed to when someone nearby sneezes, or when you touch a surface that was recently sneezed on and then touch your face, can be helpful when millions of people do the same. A T-shirt over your mouth or a handkerchief tied around your head might not protect you personally. But if enough people wear them, even a small reduction of viral load in the community will compound over time and result in a meaningful difference in the total number of cases and the load it puts on a nation's health system. That's what ultimately matters, and that's what the Japanese and Koreans understand. Any country that has the guts to order their citizens to stay home should also have the sense to order them to cover their faces with something substantial whenever they have a valid reason to be outside, e.g. going to work.