快樂小藥師 Im pharmacist nichts glücklich

Hypothetical common mechanism for intrinsic aging and photoaging.

這張圖就可以說明防曬的重要性了，其他關於防曬的知識，可以參考：

認識防曬係數，了解正確防曬原則

關於防曬的幾個指標

防曬最重要的是什麼？

正確選擇太陽眼鏡

[WebMD]如何避免日曬傷害？How to Avoid Sun Damage

眼鏡抗UV實驗Repeated cell divisions shorten telomeres. Exposure to ROS during aerobic cellular metabolism may also damage guanine residues in telomeres. During the repair of such damage, the telomere loop would be temporarily disrupted. Both critical telomere shortening and telomere loop disruption would invoke signaling leading to SOS-like responses, proliferative senescence, or apoptosis, all of which interfere with carcinogenesis. Photodamage leads to thymine dimers (UVB) and ROS (both UVA and UVB) that damage genomic DNA and give rise to mutations that may lead to cancer development. However, these lesions also damage telomeres, disrupting the telomere loop. Consequent signaling through the exposed TTAGGG sequence would lead to SOS-like responses, senescence, or apoptosis that would interfere with carcinogenesis. Abbreviation: ROS, reactive oxygen species. 

來源：Photodermatology (Basic and Clinical Dermatology) 1 edition 0849374960