The common surgical face masks you'll often see people from Asia wear in public are only useful if YOU have the virus by reducing the chance of people catching the virus from you. There are, however, N95 respirator masks that are useful for protecting the uninfected from catching the virus.

Source: https://www.cdc.gov/coronavirus/2019-ncov/hcp/respirator-use...

> only useful if YOU have the virus

Yes, but given the incubation period and so on, how do you know you don't have the virus?

I'm not going to wear a mask in Central Europe (at least not yet) but I probably would in Asia just in order to not be selfish.

Also, you and I random are not wearing it correct, that’s basically given. It requires regular trainings and tests.

What about catching the infection through the eyes?

They do stop you from breathing in contaminated particles, from spreading them when coughing / sneezing and they stop you touching your face with contaminated hands.

They aren't perfect because you still need proper technique when removing them and they "leak" along the sides etc. Still better than nothing, especially in crowded places.

They won't help you at all. All they do is creating false sense of safety. Viruses are too small and will go through the mask anyway. Also they may protect half of your face against your hands but they won't protect other half, say, against rubbing your eyes.

They may help you to minimize the spread if you are already sick, sneezing and coughing. Droplets are big enough to be stopped by mask. This is actually the reason why surgeons are wearing masks in the first place - not to contaminate the patient.

Unless we are talking about something more advanced. Like above mentioned N95.

Even a regular surgical mask that doesn't have the effectiveness of the N95 can stop water droplets (as you said) and hence, it can stop viruses.

The key insight, though, is that water droplets carry viruses; viruses can travel through masks, but they can't travel by themselves without hitching a ride on a water droplet.

This is why flu season is during the cold winter, when there isn't enough heat to instantly evaporate the moisture in the air. And this is why even a regular surgical mask can offer some protection for a healthy wearer.

That may be. But wearer of surgical mask creates moisture by breathing and a lot of it. One would suspect that kind of environment works in favor of a virus.

The N95 masks require training, and they're not for everyone. It is possible for young children to suffocate because their lungs are not strong enough to pull air through (it takes some effort).

I have asthma, and even a few hours of wearing a procedural mask, let alone an N95 mask are very taxing. Maybe for brief periods in public... But sweat transmitted by hand onto a surface is enough. Sewage in a building is enough to infect residents that don't otherwise encounter each other.