The stratospheric ozone layer which exists about 30 miles above the earth, shields the earth's surface from dangerous solar ultraviolet radiation.

Manmade chemicals such as chlorofluorocarbons break ozone down, rendering it useless for screening deadly ultraviolet radiation and increasing the level of ultraviolet radiation striking the surface of the earth.

This can result in a variety of adverse health effects for people, such as skin cancer, cataracts, and weakened immune systems, as well as other problems such as reduced agricultural crop yields.