McKenzie Richard L, Liley J Ben, Björn Lars Olof
National Institute of Water & Atmospheric Research (NIWA), Lauder, Central Otago, New Zealand.
Photochem Photobiol. 2009 Jan-Feb;85(1):88-98. doi: 10.1111/j.1751-1097.2008.00400.x. Epub 2008 Jul 22.
We use action spectra published by the International Commission on Illumination to examine diurnal, seasonal and latitudinal variations in erythemally weighted (sunburning) UV-a health risk, and vitamin D-weighted UV-a health benefit. Vitamin D-weighted UV is more strongly dependent on ozone and solar zenith angle. Consequently, its diurnal, seasonal and geographic variability is more pronounced than for erythemally weighted UV. We then investigate relationships between the two quantities. An algorithm is developed and used to relate vitamin D production to the widely used UV index, to help the public to optimize their exposure to UV radiation. In the summer at noon, there should at mid-latitudes be sufficient UV to photosynthesize optimal vitamin D in approximately 1 min for full body exposure, whereas skin damage occurs after approximately 15 min. Further, while it should be possible to photosynthesize vitamin D in the winter at mid-latitudes, the amount of skin that must be exposed is larger than from the hands and face alone. This raises the question of whether the action spectrum for vitamin D production is correct, since studies have reported that production of vitamin D is not possible in the winter at mid-latitudes.
我们使用国际照明委员会发布的光谱，来研究红斑加权（晒伤）紫外线A健康风险的日变化、季节变化和纬度变化，以及维生素D加权紫外线A的健康益处。维生素D加权紫外线对臭氧和太阳天顶角的依赖性更强。因此，其日变化、季节变化和地理变化比红斑加权紫外线更为显著。然后，我们研究这两个量之间的关系。开发了一种算法，并将其用于将维生素D的生成与广泛使用的紫外线指数相关联，以帮助公众优化其紫外线辐射暴露量。在夏季中午，中纬度地区应该有足够的紫外线，全身暴露大约1分钟就能合成最佳量的维生素D，而皮肤损伤大约在15分钟后发生。此外，虽然在中纬度地区冬季应该有可能合成维生素D，但必须暴露的皮肤面积比仅暴露手和脸的面积要大。这就引发了维生素D生成的光谱是否正确的问题，因为有研究报告称，在中纬度地区冬季不可能生成维生素D。
