ABSTRACT

Visible sunlight is only a tiny part of the whole radiation spectrum emitted by the sun (400-700 nm). By increasing wavelength >700 nm, one enters the invisible radiation range called infrared (IRR), and by decreasing wavelength <400 nm, one enters the ultraviolet (UVR) domain. Overexposure to the sun’s visible and invisible rays can be harmful to human skin. The damage can be immediate with effects appearing some hours later such as erythema and sunburn leading to cell and tissue degradation. The damage can also be long term (over years), and cumulative effects of prolonged exposure are now increasingly recognized to be the possible cause of degenerative changes in the skin such as premature wrinkling and skin cancers. Indeed, many skin changes that often are identied with aging actually result from damage by too much sun exposure [1-4].