In 1974, chemists F. Sherwood Rowland and Mario Molina warned that chlorofluorocarbons (CFCs), widely used as refrigerants, were destroying the ozone layer.

Using a spectrometer, British researchers discovered the ozone hole in the lower stratosphere over Antarctica in the mid-1980s.




The hole swells and contracts; it grew largest in Sept. 2000, spanning about 17.5 million square miles.