You might want to try a rather neat and inexpensive trick we've been using for years....using your fingers, daba tiny bit ofconcentrated dish washing liquid (we use a clear liquid, like Dawn) on both sides of the lens, spread a thin filmoverthe surfaces of both sidesand then wipe the lens clean (do NOT rinse) and buff dry; the thin film of soap breaks up water molecules and noticeably reduces fogging. Although it may not work as well as some of the commercial products specifically designed for de-fogging lens (especially if you wear a full head net), it sure does work well enough it most instances to make it worth spending the 30 seconds or so to do... and basically costs nothing.