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Message:: [QUOTE="Kasia, post: 1299895, member: 31533"]If no ray of sunlight is going to get within X number of feet, then it is not in direct or indirect sunlight. But if when the window is open (as in shades not drawn or blinds not down, and blocking sunlight completely) then sunlight does come in, the area is in sunlight (indirect), so it does get within X number of feet. It will eventually have an effect on the coins. It is the LIGHT source (even artificial light) which contains UV light that can break down the surface of any item. Direct sunlight, where an item is exposed not only to the UV rays but also to the wind and weather will break down first, but items exposed to UV light frequencies will break down regardless of the source of the UV light. It is not the HEAT from the light source but the wavelength of the light source, which as we know it is the UV spectrum, that is harmful to items over the long run. There may be other wavelengths of light also harmful, but the most common that people realize does harm is the UV spectrum. Eventually, ANY light source will harm an item, but it is generalized that artificial light sources are ok, as the length of time it would take to harm something with artificial light is a very long period of being exposed to it. Even in museums, which display items in the light, the exhibits can be either rotated out of use, and stored better, or they are "cleaned" or "conserved" depending on the museum.[/QUOTE]