u/Embarrassed_Rest_342

I have this skein in my stash, and it's been there for admittedly awhile with no plans (looking for the perfect project, as always....). I went looking for something else and noticed this had happened. There was a lot of dust on the fibers and tiny bits of dirt that are grainy like sand or kitty litter. A bunch of the strands are broken, mostly in one spot as seen in the picture. My stash is kept in a couple of open shelves in my front room, which is well-lit and used. It was between the basket and the yarn in plastic. No other yarn seems affected. Is it salvageable? What happened?