THE AMBIENT OUTDOOR ULTRAVIOLET AND BLUE-LIGHT ENVIRONMENT: SEASONAL VARIATIONS AND THEIR POTENTIAL IMPACT FOR HUMAN HEALTH

摘要

It is well known that short-termoverexposure to solar radiation can lead to acute injuries such as erythema and photokeratitis, and chronic overexposure can lead to increased risk of some types of skin cancers, photoageing of the skin, pterygium and cataract. Recent studies, however, have increased the awareness of the benefits of moderated solar radiation exposure, particularly with regard to ultraviolet radiation's role in previtamin D3 synthesis in human skin, and blue, diffuse sky radiation's important role in the regulation of the melatonin cycle in humans. We weighted modelled solar spectra with the CIE erythema action spectrum in order to demonstrate the seasonal variation of risk, and weighted the same spectra with the action spectrum for synthesis of previtamin D3 in human skin to determine the variation of seasonal benefit for this effect. Further, we measured the spectral radiance of various parts of the sky (clouds, diffuse blue sky, hazy blue sky, etc.) in February, June and July 2006, in order to evaluate the potential for a seasonal dependence for melatonin regulation, erythema risk, and previtamin D3 production.