The ozone hole may be recovering, according to a study released by the US National Aeronautics and Space Administration (NASA) last week.
Using measurements from the Aura satellite, NASA scientists have been studying the levels and rates of chlorine within the ozone hole over Antarctica during the past few years.
Studies show that chlorine levels in the hole are decreasing. NASA says this is "the first definitive evidence on the success of the Montreal Protocol on Substances that Deplete the Ozone Layer.
The 1987 Montreal Protocol prohibits chemicals that destroy the Earth's protective ozone layer, such as chlorofluorocarbons (CFCs) previously used in refrigerants, engines, and pesticides.
The study found about 20 percent less ozone depletion during the Antarctic winter than there was in 2005, the first year that measurements of chlorine and ozone during the Antarctic winter were made by NASA's Aura satellite.