The hole in the ozone layer has shrunk thanks to a worldwide ban on damaging chemicals, according to NASA scientists.
In a study published this week, scientists found that a decline in levels of ozone-destroying chlorine had resulted in a 20 percent decrease in ozone depletion during the winter months from 2005 to 2016.
NASA credited the recovery to the Montreal Protocol, a 1989 initiative to phase out man-made ozone-depleting chemicals called chloroflurocarbons (CFCs), which were once widely used in aerosols, fridges, packing materials and air conditioning.
“We see very clearly that chlorine from CFCs is going down in the ozone hole, and that less ozone depletion is occurring because of it,” Susan Strahan, lead author and atmospheric scientist from NASA’s Goddard Space Flight Center, said in a statement.
The study, based on data from the Aura satellite, was the first to look directly at measurements of chemicals to argue that the shrinking hole is a result of the CFC ban.
The ozone layer protects the Earth from ultraviolet radiation, which can cause skin cancer and cataracts, and damage plants.
A hole in the layer was first spotted in the 1980s and blamed largely on CFCs, which are broken down by the sun’s ultraviolet radiation when they rise into the stratosphere, releasing chlorine atoms that go on to destroy ozone molecules.
But while the hole is recovering, scientists warned that it will take decades for the CFCs to fully leave the atmosphere.
"CFCs have lifetimes from 50 to 100 years, so they linger in the atmosphere for a very long time," said Anne Douglass, the study's co-author.
"As far as the ozone hole being gone, we're looking at 2060 or 2080. And even then there might still be a small hole."