Rain-X, the company that makes the windshield treatment also makes an 'Anti-fog' product that works great on interior glass and on eyeglasses. I've used it on my cars with great success. It should be available in most parts stores; the bottle that it comes in is black and it is about the same size as their yellow bottle of windshield treatment.also, you can try cleaning the windows with vinegar and water. use 1 tablespoon of regular white vinegar to one quart of water and you'll get the windows cleaner than they've ever been. That will deminish a great deal of the fogging by itself.hope that helps