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Sunburn and its prevention.

Summary 
 
Since the discovery, approximately a century ago, of the role played by solar ultraviolet radiation in determining the state of the skin's health, much progress has been made in gaining a more exact understanding of the relationship which exists between skin and sun. In this review there has been an attempt to trace the discoveries that have been made towards interpreting the physical and chemical reactions responsible for the development of ultraviolet erythema in the skin. Consideration has been given to such factors as the intensity and duration of radiation, the specific wavelengths involved, the mechanism of the inflammatory response and the relative susceptibility of different skin types. Other forms of skin damage in relation to solar erythema are also considered. The development and comparative effectiveness of the body's natural defence systems against this erythema has been discussed in so far as present knowledge of these aspects is concerned. The use, protective ability and methods of evaluation of sunscreen preparations have also been considered. The necessity for using these preparations on a daily basis is stressed.