Cut a sleeve off an old thin worn-out T-shirt you are going to cut off for rags.
Stretch it out, it will fit as a mask. Like breathing through gossamer.
Wear a fishing buff.
Great idea, Thanks!
After you cut the rectangle, cut about 1/2 inch from each end about 3/4 of the way to the other side. These cuts will make loops to go around your ears. Cheap, washable and easy to make.