This site explains the layers of Earth’s atmosphere, including the stratosphere, where the ozone is most concentrated; the harmful effects of the UVB portion of ultraviolet light; and the effects of chlorofluorocarbons on the ozone layer. The history of ozone depletion and the world’s reaction to it is presented. There is also information on U.S. Environmental Protection Agency programs to prevent ozone layer depletion and other links to the history and science of ozone depletion.