Masks are not established to reduce the spread of CV's. They will however lower the blood oxygen content of the people using them. It's entirely possible they a

Masks are not established to reduce the spread of CV's. They will however lower the blood oxygen content of the people using them. It's entirely possible they are a net negative. Also, a non trivial # of people are driving with then, walking outside, riding their bike... I could go on. And then theres that psychological elephant in the room.