L'Oréal Research and Innovation, France.
Indian J Dermatol Venereol Leprol. 2012 Jun;78 Suppl 1:S9-S14. doi: 10.4103/0378-6323.97350.
Solar ultraviolet (UV) radiation reaching the earth is a combination of UVB (290-320 nm) and UVA (320-400 nm) wavelengths. Since UVA is less energetic than UVB, UVB has long been thought to be the factor responsible for the damaging effects of solar radiation. But with modern tools such as in vitro models, it has been proven that UVA plays a major role. The objective of this review is to show how skin may be exposed to UV light and to highlight the clinical aspects of UV-induced skin damages with the respective contribution of UVB or UVA. Even if UVA is less energetic than UVB, it is more abundant and penetrates deeper into the skin, reaching as far as the dermis. Various factors also influence skin exposure to UV light: the latitude, season, and time of the day. Acute as well as chronic sun exposure induces short- and long-term clinical damages. Erythema and pigmentation are immediate responses of normal human skin exposed to UV radiation. The long-term effects are photoaging and photocarcinogenesis. In particular, UVA appears to play a major role in the deterioration of dermal structure leading to the photoaged appearance of the skin.
到达地球的太阳紫外线（UV）辐射是 UVB（290-320nm）和 UVA（320-400nm）波长的组合。由于 UVA 的能量比 UVB 低，因此长期以来，人们一直认为 UVB 是导致太阳辐射破坏性影响的因素。但是，借助于体外模型等现代工具，已经证明 UVA 起着主要作用。本篇综述的目的在于展示皮肤如何暴露于紫外线下，并突出显示 UV 诱导的皮肤损伤的临床方面，以及 UVB 或 UVA 的各自贡献。即使 UVA 的能量比 UVB 低，但它更为丰富，并且能够更深地穿透皮肤，甚至到达真皮层。各种因素也会影响皮肤对紫外线的暴露：纬度、季节和一天中的时间。急性和慢性日晒都会引起短期和长期的临床损伤。红斑和色素沉着是正常人类皮肤暴露于 UV 辐射后的即时反应。长期影响则是光老化和光致癌作用。特别是，UVA 似乎在导致皮肤真皮结构恶化，使皮肤呈现光老化外观方面起着主要作用。
