National Centre for Epidemiology and Population Health, Research School of Population Health, The Australian National University, Canberra, Australia.
Photochem Photobiol Sci. 2018 Dec 5;17(12):1956-1963. doi: 10.1039/c7pp00374a.
Exposure of the skin to ultraviolet (UV) radiation is the main risk factor for skin cancer, and a major source of vitamin D, in many regions of the world. Sun protection messages to minimize skin cancer risks but avoid vitamin D deficiency are challenging, partly because levels of UV radiation vary by location, season, time of day, and atmospheric conditions. The UV Index provides information on levels of UV radiation and is a cornerstone of sun protection guidelines. Current guidelines from the World Health Organization are that sun protection is required only when the UV Index is 3 or greater. This advice is pragmatic rather than evidence based. The UV Index is a continuous scale; more comprehensive sun protection is required as the UV Index increases. In addition, a wide range of UVA doses is possible with a UVI of 3, from which there may be health consequences, while full sun protection when the UVI is "moderate" (between 3 and 5) may limit vitamin D production. Finally, the duration of time spent in the sun is an essential component of a public health message, in addition to the intensity of ambient UV radiation as measured by the UV Index. Together these provide the dose of UV radiation that is relevant to both skin cancer genesis and vitamin D production. Further education is required to increase the understanding of the UV Index; messages framed using the UV Index need to incorporate the importance of duration of exposure and increasing sun protection with increasing dose of UV radiation.
皮肤暴露于紫外线（UV）辐射是皮肤癌的主要危险因素，也是世界上许多地区维生素 D 的主要来源。保护皮肤免受皮肤癌风险的信息，但又要避免维生素 D 缺乏，这是一个挑战，部分原因是紫外线辐射水平因地点、季节、一天中的时间和大气条件而异。紫外线指数提供了紫外线辐射水平的信息，是防晒指南的基石。世界卫生组织目前的指南规定，只有当紫外线指数达到 3 或更高时，才需要进行防晒。这种建议是务实的，而不是基于证据的。紫外线指数是一个连续的尺度；随着紫外线指数的增加，需要更全面的防晒措施。此外，在紫外线指数为 3 的情况下，可能会有多种 UVA 剂量，其中可能会有健康后果，而当紫外线指数为“中等”（3 至 5 之间）时，进行全面防晒可能会限制维生素 D 的产生。最后，在阳光下的时间长短是公共卫生信息的一个重要组成部分，除了环境紫外线辐射的强度（由紫外线指数测量）。这些共同提供了与皮肤癌发生和维生素 D 产生相关的紫外线辐射剂量。需要进一步教育以提高对紫外线指数的理解；使用紫外线指数制定的信息需要纳入暴露时间和随着紫外线辐射剂量的增加而增加防晒措施的重要性。
