An international ban on chlorine-containing man-made chemicals called chlorofluorocarbons (CFCs), has resulted in about 20 per cent less ozone depletion, NASA said.
“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,” said Susan Strahan, from the US space agency.
By comparing the Microwave Limb Sounder (MLS) measurements of hydrochloric acid and nitrous oxide each year, the scientists determined that the total chlorine levels were declining on average by about 0.8 per cent annually. PTI The Antarctic ozone hole forms during September in the Southern Hemisphere’s winter as the returning sun’s rays catalyse ozone destruction cycles involving chlorine and bromine that come primarily from CFCs.
The change in ozone levels above Antarctica from the beginning to the end of southern winter – early July to mid- September – was computed daily from MLS measurements every year from 2005 to 2016.
The scientists found that ozone loss is decreasing, but they needed to know whether a decrease in CFCs was responsible. PTI