The layer of ozone which hangs in the atmosphere from 20 to 40 miles above the surface of the earth and protects the earth from excessive ultraviolet radiation.

Some experts claim that the manufacture of various chemicals; such as, chlorofluorocarbons used as propellants in aerosol sprays, and the effects of high-flying jet aircraft are destroying this protective layer and allowing excessive amounts of ultraviolet radiation to penetrate the earth's atmosphere; therefore, subjecting humans to increased dangers of skin cancer and other health problems.