The issue is when sick people do not know they are sick. Where my brother works they have to wear masks (without valves....they caught on the "protecting me" part).Sick people shouldn't be breathing on you in the first place. You wearing a mask is lowering your immune system. I hardly ever wear a mask, but if I do it's a N-95 that I have passed fit test for. It has an exhaust valve. It's protecting me.
I don't always wear a mask, but when I do they are usually cloth masks with three layers...the two inside layers having become strangely missing .