Rowland, Frank Sherwood (1927-...), an American chemist, helped to alert the scientific community to the threat to the ozone layer posed by chlorofluorocarbons (CFC's), the artificial substances that were widely used in spray-cans and refrigerators. The ozone layer is a layer of the upper atmosphere with a high concentration of ozone, a form of oxygen. This layer shields the earth's surface from the sun's ultraviolet radiation. Rowland did this work with Mario J. Molina, and the two shared the 1995 Nobel Prize for chemistry with Paul Crutzen, a Dutch chemist who also worked on dangers faced by the ozone layer.