The radiation hazard has been estimated for 6 light sources commonly used in museums (skylight, sunlight, incandescent-lamp light, and light from three fluorescent lamps: daylight, cool- white deluxe, warm-white deluxe). Similar estimates have been made for each of these light sources screened by each of four ultraviolet-absorbing filters (Kingsport water-white glass, ordinary window glass, Corning Greenish Nultra glass, and Corning Noviol O glass). Probably rate of damage was estimated chiefly on the basis of photochemical deterioration of cellulose. Unfiltered skylight was found to have the highest probably rate of damage per footcandle; incandescent-lamp light filtered through Corning Noviol O glass was estimated to have about 1% of this hazard.