I’d disagree with that. The inside of the mask accumulates breath bacteria, and, outside a virus environment, is the dirtiest part of the mask
Yup, but that's why we rotate our N95 masks. They come in boxes of 20. We labelled 14 of them with our initials, 7 with T for me and 7 with C for my wife, and also by initials for days of the week. 6 we kept as spares. When either of us goes out, mostly my wife, we wear the mask for that day of the week. Ditto for my brothers and their wives. I sent them a box of 20 N95's each.
And the problem IS a virus environment.