( CNN ) -- The ozone hole over Antarctica in 2008 is larger in both size and ozone loss than last year , but not as large as in 2006 , the European Space Agency said Tuesday . Some chemical processes produce ozone-depleting gases . The hole is a thinning area in the ozone layer over Antarctica and the size of the hole varies every year depending on weather conditions . This year , the size of the thinned area reached about 27 million square kilometers ( 10.4 million square miles ) , compared to 25 million square kilometers ( 9.65 million square miles ) in 2007 . In 2006 , the hole was a record 29 million square kilometers ( 11.2 million square miles ) , larger than North America , the ESA said . The ESA announced its results based on information from German and Dutch researchers who analyzed satellite data . Depletion of ozone is caused by extreme cold temperatures at high altitude and the presence of ozone-destroying gases , such as chlorine and bromine , in the atmosphere , the ESA said . Those gases originate from man-made products like chlorofluorocarbons , or CFCs , which were phased out under a global agreement two decades ago but continue to linger in the atmosphere . Ozone is a protective atmospheric layer found at an altitude of about 25 kilometers ( 15.5 miles ) . It acts as a sunlight filter , shielding life on Earth from harmful ultraviolet rays that put humans at greater risk of skin cancer and cataracts and harm marine life , the agency said .
2007 ozone hole larger than in 2008 , ESA says . It covers area of 10.4 million square miles . Ozone layer acts as a sunlight filter , shielding Antarctica from some ultraviolet rays .