Dr Norman Swan, Physician and Journalist
How good a mask is at protecting others, let’s start with others rather than yourself. Depends on how the mask is made. So any mask, even a single layer cotton mask is better than no mask at all. But a cotton mask can get, a single layer cotton mask can get wet very quickly and lose its effectiveness.
Recent research has shown that a double layer mask can stop aerosol spreads. That’s two layers of cotton, but a three layer mask is even better. And best of all is a proper surgical mask. You don’t need an N95 mask to protect others, but it can be good for protecting yourself if you’re at risk.
How do you know if you’ve got a good seal around your mask?
But if you don’t know how to get a perfect seal around your mouth, for example, if you spray perfume nearby and you can smell it, it’s not a perfect seal. And a surgical mask is just as good, and you might as well save your money. So, common sense, more layers, the better. You’ve gotta be able to breathe through it fairly easily. But any covering at all is better than none in terms of protecting others. In terms of protecting yourself, the N95 with a proper seal is the best. But if you can’t get a proper seal, just save your money and get a surgical mask.