Dermatology Melanoma / Photobiology Etiology




Penetration of human skin by ultraviolet light

John L. Bezzant, M.D.

The longer the wavelength of light, the deeper the penetration of the light into the skin. Ultraviolet light is generally divided into ultraviolet C (200 to 280 nanometers), ultraviolet B (280 to 320 nanometers), and ultraviolet A (320 to 400 nanometers). Of the light that reaches the surface, ultraviolet B (mid-wavelength ultraviolet light) appears to be the most carcinogenic.