CFC making ozone hole in the stratosphere
We will learn more in Global warming chapter

Ozone layer depletion, is simply the wearing out (reduction) of the amount of ozone in the stratosphere. Depletion begins when CFC's get into the stratosphere. Ultra violet radiation from the sun breaks up these CFCs. The breaking up action releases Chlorine atoms.

Ozone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere (the ozone layer), and a much larger springtime decrease in stratospheric ozone around Earth's polar regions.[1] The latter phenomenon is referred to as the ozone hole.