Project Sunscreen Protection

Abstract

The sun emits cosmic rays, gamma rays, X-rays, ultraviolet (UV) radiation, visible radiation, infra-red radiation and radio waves. UV radiation - and to a much lesser extent visible and infra-red radiation - is capable of causing biological reactions in the skin. The UV region of the spectrum can be divided into three categories: UVC (200–290 nm), UVB (290–320 nm) and UVA (320–400 nm). Solar UVC radiation does not reach the earth’s surface because it is absorbed by atmospheric ozone. Some solar UVB radiation, however, does reach the earth’s surface and this can cause harmful effects in human skin [1, 2]. These effects include sunburn (or erythema), suntanning, photoageing (deposition of abnormal elastin fibres, collagen degeneration and damaged microvasculature), and skin cancers. One beneficial effect of UVB radiation is that it converts sterol precursors in the skin, such as 7-dehy-drocholesterol, to vitamin D, which is essential for calcium metabolism [3].