A tight fitting (in occupational health this means "proved via fit testing") N95/FFP2 or higher filtering facepiece respirator is excellent protection for the w

A tight fitting (in occupational health this means "proved via fit testing") N95/FFP2 or higher filtering facepiece respirator is excellent protection for the wearer regardless of what anyone else is or isn't wearing. Assuming of course that the wearer doesn't remove the mask to eat something, etc. Masks, which can be loose fitting and have lower filtration performance, are where you really need everyone wearing them since they perform best as source control. But for those who want to be more cautious, wearing a N95 class "mask" (FFR) even if others around you are not masking is still highly effective.