2008 Ozone Hole Fifth Largest On Record

This year's hole in the stratospheric ozone layer is the fifth largest on record, the National Oceanic & Atmospheric Administration announced last week. The ozone hole reached its maximum size on Sept. 12, covering an area of 10.5 million sq miles and extending 4 miles deep, according to NOAA. The record ozone hole was measured in 2006, peaking at a size of 11.4 million sq miles. Massive depletion of ozone occurs every austral spring over Antarctica, mainly due to bromine and chlorine released in the breakdown of synthetic compounds such as chlorofluorocarbons. The ozone hole's size fluctuates from year to year because of changes in wind and weather conditions. Although countries are phasing out the production of CFCs and several other types of ozone-depleting chemicals, these substances typically last decades in the atmosphere and take several years to rise to the stratosphere, NOAA says. The agency doesn't expect the effects of the phaseout to lead to a full recovery of Antarctic ozone until after 2050.