Rob Do you have the vented or non vented? I have both and the non vented seems to fog up a lot more. You can tell by looking at the rubber foam part that lays against your face. It will either be solid all the way around, or have indentions for air flow. I have also noticed if you leave it on your head prior to blast off it doesn't fog as bad either. As it is already being exposed to the elements. I have also noticed that on long runs my breathe alone inside the closed mask will make it fog up. There is no where for the warmer air to escape.