Centre for Rural and Remote Area Health, University of Southern Queensland, Toowoomba, Queensland 4350, Australia.
Radiat Res. 2010 Mar;173(3):373-9. doi: 10.1667/RR1951.1.
Abstract This paper reports on the variation of UV radiation in full sun and in shade and how this relates to the physiological production of vitamin D(3) for various latitudes. Calibrated spectral measurements were used to measure the UV radiation in the shade of numerous shade environments for varying solar zenith angles and seasons. This was for exposures to the horizontal, 45 degrees and vertical planes for the solar zenith angle (SZA) range of approximately 5 degrees to 80 degrees. For an SZA of approximately 5 degrees, average UV irradiances required for vitamin D(3) production (UV(D3)) were 0.67 W/m(2) and 0.20 W/m(2) for global and for shade with a sky view of greater than 40%, respectively. The best time to expose the human body to UV radiation while using shaded environments with a sky view of greater than 40% for vitamin D(3) synthesis is for SZAs less than approximately 45 degrees. Shade can be used throughout Australia during summer and winter. However, winter exposure times will vary depending on the latitude. Using shade for UV(D3) exposures can reduce total UV-radiation exposure by 37% to 58% compared to full sun UV(D3) exposures. This research indicates that an improved approach to optimize UV-radiation exposures for the production of vitamin D(3) is to use diffuse UV radiation under shade in and around the middle of the day.
摘要 本论文报告了全阳光和阴影下的紫外线辐射变化，以及其与不同纬度下维生素 D(3)的生理产量之间的关系。我们使用校准的光谱测量来测量各种太阳天顶角和季节下众多阴影环境中的紫外线辐射。这些测量是针对太阳天顶角（SZA）范围约为 5 度至 80 度的水平、45 度和垂直平面进行的。对于 SZA 约为 5 度的情况，全球和天空视场大于 40%的阴影环境中，产生维生素 D(3)所需的平均紫外线辐照度（UV(D3)）分别为 0.67 W/m(2)和 0.20 W/m(2)。在天空视场大于 40%的阴影环境中，人体暴露于紫外线辐射的最佳时间是 SZA 小于约 45 度。在澳大利亚的夏季和冬季都可以使用阴影。然而，冬季暴露时间将取决于纬度。与全阳光 UV(D3)暴露相比，使用遮荫环境进行 UV(D3)暴露可将总紫外线辐射暴露量减少 37%至 58%。这项研究表明，优化紫外线辐射暴露以产生维生素 D(3)的一种改进方法是在中午时分在室内和周围使用漫射紫外线辐射。
