One of the major threats to the environment is destruction of stratospheric ozone by substances released to the atmosphere that catalyze conversion of O, back to O2. The major culprit in ozone depletion consists of CFC compounds, commonly known as "Freons." In 1974 it was convincingly suggested by Mario Molina and F. Sherwood Rowland that chlorofluoromethanes could catalyze the destruction of stratospheric ozone. Subsequent data on ozone levels in the stratosphere and on incre- ased ultraviolet radiation at the earth's surface showed that the threat to stratospheric ozone posed by CFCs is real. Along with atmospheric scientist Paul Crutzen, these investigators received a richly deserved Nobel Prize in 1995 for this classic work