Antarctic ozone hole 2005. Coloured satellite image of low atmospheric ozone levels over Antarctica on 11th September 2005. The ozone hole (dark blue) is 27 million square kilometres in size. The largest hole was 29.2 million square kilometres in 2000. Ozone levels are colour- coded, from dark blue (lowest), through cyan and green to yellow (highest). Ozone absorbs harmful ultraviolet (UV) radiation from the Sun, but its levels are reduced by chlorofluorocarbons (CFCs) and other compounds. CFC production was restricted in 1987, but the hole will take decades to heal. Data from the Ozone Monitoring Instrument on the Aura satellite.