Nobody knows. We know that "real" masks (i.e. n95 or better) are effective when worn properly, but many people don't wear them properly. The evidence for effec

Nobody knows. We know that "real" masks (i.e. n95 or better) are effective when worn properly, but many people don't wear them properly. The evidence for effectiveness of other kinds of masks in the prevention of virus transmission is weak, at best.