Researchers say they have found the first clear evidence that the thinning in the ozone layer above Antarctica is starting to heal.
The scientists said that in September 2015 the hole was around 4 million sq km smaller than it was in the year 2000 - an area roughly the size of India.
The gains have been credited to the long term phasing out of ozone-destroying chemicals.
The study also sheds new light on the role of volcanoes in making the problem worse..
However others are not entirely convinced that the decline shown in the new study is down to a reduction in the amount of chlorine in the stratosphere.
"The data clearly show significant year to year variations that are much greater than the inferred trends shown in the paper," said Dr Paul Newman from Nasa.
"If the paper included this past year, which had a much more significant ozone hole due to lower wave driven forcing, the overall trend would be less."..
Sign up with Google