Diseases Due to Ultraviolet Radiation

Abstract

Skin is the only organ exposed to ultraviolet radiation of the sun. The sun emits a continuous spectrum of electromagnetic energy, from the short cosmic rays to the long radio waves. Between these extremes we have the ultraviolet radiation (UVR) and visible light. The wavelength of UVR ranges from 200 to 400 nm and visible light from 400 (violet) to 700 (red) nm UVR spectrum consists of three wavebands, UVC, UVB and UVA. UVC (200–290 nm) is mostly absorbed by the ozone layer of the atmosphere. Most of the damage to the skin is by UVB (290–320 nm) and UVA (320–400 nm). The shorter wavelengths (cosmic, gamma and X-rays) are filtered out by the atmosphere and the larger wavelengths (infrared, radio rays) rarely plays a role in skin damage.