A rare hole in the ozone layer above the Arctic Circle that opened suddenly in February and grew to become the largest ever recorded has finally closed, CNN reported.
The ozone layer blocks harmful UV radiation from reaching the planet's surface. The Antarctic ozone layer hole was directly caused by chemical reactions from chlorofluorocarbons, or CFCs, and it caused a spike in skin cancer rates in countries like Australia.
That realization led to a ban of products containing CFCs in 1996, and since then the ozone hole over the Antarctic has been getting smaller and smaller.
"Polar vortex" is a term many have become familiar with as it causes bone-chilling temperatures during winter when air that's normally in the Arctic gets pushed down into more traditionally temperate areas.
In this case, the polar vortex depleted the ozone layer as high as 11 miles into the stratosphere. The ozone layer typically extends between 9 and 22 miles up.
But the last time was in 2011, and before then, 1997.
"While such low levels are rare, they are not unprecedented," NASA researchers said, according to CBS News. Given the decade between previous ozone-depletion events, experts do not expect a similar hole to appear next year.
Experts stressed that human activity, or lack thereof due to COVID-19 restrictions, had nothing to do with the ozone hole closing up; the reports of air clearing up as traffic and industry production ground to a halt had no impact on the ozone hole.
"Actually, COVID19 and the associated lockdowns probably had nothing to do with this," the Copernicus Atmospheric Monitoring Service (CAMS) tweeted. "It's been driven by an unusually strong and long-lived polar vortex, and isn't related to air quality changes."