Measurement of erythemal response to ultraviolet radiation by "monochromatic" photography.

The main early color change induced by ultraviolet light consists of a decreased oxyhemoglobin reflectance. A method is presented in which the skin together with a calibrated gray scale is photographed using an interference filter with a peak transmission at 540 nm, the region of the specific absorption bands of hemoglobin. On the processed photographs the irradiated skin can then be compared with the calibrated scale and thus the degree of ultraviolet erythema calculated.