11.   By now everyone knows that it is ultraviolet, or UV, rays that both tan and damage the skin.

12.   Every time you get a tan, you have damaged the skin, triggering a repair mechanism that produces melanin in a vain attempt to protect the skin.

13.   It rarely spreads to other organs, although it can markedly damage skin around and beneath it.

14.   Sunbathers already know that constant exposure can prematurely damage their skin, causing wrinkles and heightening their risk of skin cancer.

15.   These highly reactive chemicals are produced by exposure to ultraviolet light and are known to be involved in reactions that damage the skin.