Antarctic ozone hole. Coloured satellite image of the reduced atmospheric ozone layer over Antarctica on 24th September 2006. Ozone layer thicknesses are colour coded from purple (lowest) through blue, cyan and green to yellow (highest). The purple regions have an ozone layer that is about 40% thinner (at 100-200 Dobson units) than normal (300-340 Dobson units). Ozone absorbs harmful ultraviolet (UV) radiation from the Sun, but its levels are reduced by chlorofluorocarbons (CFCs) and other compounds. 2006's hole set records for extent (over 29.5 million square kilometres) and ozone depletion (to 85 Dobson units), but it is still hoped that the hole will recover fully by the middle of the century. Data from the Ozone Monitoring Instrument on the Aura satellite.