Dave:
I don't use a mask ( I assume you mean a face shield) at the scroll saw, or the band saw. However, I always use a shield at the lathe; and occasionally at the table saw. Fogging was always an issue until a got a powered face shield. There are several brands, and they all share one thing - they are pricey. I wouldn't go back. They give better physical protection, they filter the air blown across your face, and that moving air prevents condensation from forming on your glasses as well as on the interior of the shield.