The Truth About Sunscreens

Sunscreens first came into use in the 1940s and the concept of the sun protection factor (SPF) was developed in the 1960s. The purpose of these agents is to protect against ultraviolet light. Ultraviolet light has been divided into three bands: ultraviolet C, which never reaches the surface of the earth, ultraviolet B which extends from 290-320 nanometers, is the primary cause of sunburn and does not penetrate window glass and ultraviolet A 320-400 nanometers, which does penetrate window glass and is adjacent to the visible light spectrum.