Photomonitoring strips recently developed by the present author were exposed for 50 hours to 4 light sources usually used for exhibitions at various illuminances and color differences (DELTAE) were measured from the original. The illuminances required for causing a given DELTAE (about 6) after 50 hours'exposure are in the following order: Non-UV fluorescent lamp (color temperature 4500°k) Ü0 non-UV fluorescent lamp (color temperature 3000°k)Ü0Ü0 incandescent lamp (with cold mirror) Ü0 incandescent lamp. The monitoring strips showed that the color difference caused by the exposure to a light source was reduced by 10 C4 30% through a sheet of glass, without significant change in illuminance. The author, therefore, states that even non-UV fluorescent lamps can be used safely for illuminating works of art when used through a sheet of glass. -- AATA