Is my cloth mask good enough to face the delta variant? - PolitiFact

… "When I saw those results, I threw away my cloth mask," said Stephen Luby, a co-author of the study and professor of infectious disease at Stanford University. "If delta is circulating and if you're going to wear a mask, why don't you wear one that the data tell you is good?"…

https://www.politifact.com/article/2021/sep/20/ask-khn-politifact-my-cloth-mask-good-enough-face-/