Illustrated Glossary of Organic Chemistry

Ozone depletion: Removal of ozone from the Earth's ozone layer, both by chemicals of man-made origin such as CFCs and nitric oxide, and by natural substances such as methyl bromide.

Stratospheric photolysis of CFCs such as Freon-12 establishes a radical chain reaction, resulting in the destruction of thousands of moles of ozone per mole of CFC.

Ozone depletion results in seasonal ozone holes over the Earth's Antarctic and Arctic regions. In this false color image of the largest recorded Antarctic ozone hole (September 24, 2006), purple = low ozone concentration; green = high ozone concentration.