Close-up of an aerosol spray can in action. Aerosol sprays are powered by chemicals called chlorofluorocarbons (CFCs). There is growing evidence that CFCs rise high into the atmosphere & deplete the ozone layer which protects us from the Sun's ultraviolet radiation. Chemical reactions triggered by CFCs have been implicated in the ozone hole" that has appeared recently over Antarctica each austral spring (September- October). Because increased ultraviolet is a threat to human health, notably as a cause of skin cancer, an international treaty to limit production of CFCs was signed in 1987. CFCs are also used in refrigerants & fast-food packaging."