...and everyone is wrong. This was originally in the WSJ, a source I respect. So the masks that people usually wear, or are required to wear, are only marginally better than nothing at all. Other types of masks do better, sometimes much better.
I know that many of my readers would prefer that I say "No, masks are worthless and requiring them is Soviet Union stuff." (No, I am not exaggerating.) But I like data and people who are trying to find out the real answers to things. I get the idea "Therefore, requiring people to wear those useless things is an unfair limitation on freedom, and just stupid to boot." Fine. But it so often leads to blanket rejection of all masks, and all limitations, often in high dudgeon*, that I prefer to draw the line at using any kind of mask and hope to move up from there.
*Is there low dudgeon? Apparently not.