The ultraviolet (UV) rays that cause suntans also cause a kind of chemical, called endorphins, to be released into the blood.
造成皮肤晒黑的紫外线，也会造成一种称为脑内啡的化学物质被释放进血液中。
2
Ozone is the earth's barrier against ultra-violet radiation.
臭氧是地球防止紫外线辐射的屏障。
《牛津词典》
3
The destruction of Earth's ozone layer, for example, could contribute to the general process of impoverishment by allowing ultra-violet rays to harm plants and animals.