masks mainly only matter when (1) you’re infected but don’t know it, or (2) you’re often in high face-to-face interaction situations (like medical care workers

masks mainly only matter when (1) you’re infected but don’t know it, or (2) you’re often in high face-to-face interaction situations (like medical care workers or cashiers) (also, you can edit your comment to say masks instead of balls, as you apparently intended.)