An "unprecedented" ozone hole in the Arctic which grew to be the largest-ever recorded in the Northern Hemisphere, has closed.
Scientists from the Copernicus' Atmospheric Monitoring Service (CAMS) announced the closure of the Greenland-sized hole last Thursday on Twitter.
Maintaining the ozone layer is important to protect humans and animals from radiation from the sun which causes increased rates of skin cancer.
But despite COVID-19 lockdown restrictions leading to a significant reduction of air pollution, the scientists say the pandemic wasn't the reason for the closure.
"COVID-19 and the associated lockdowns probably had nothing to do with this," the group wrote on Twitter.
"It's been driven by an unusually strong and long-lived polar vortex, and isn't related to air quality changes."
The scientists added: "This ozone hole was basically a symptom of the larger problem of ozone depletion, and closed because of local annual cycles, not long-term healing.
"But, there's hope: The ozone layer is also healing, but slowly."
The hole was created by a polar vortex, which is a large area of cold air and low pressure which surrounds the Earth's poles.
CAMS says the Arctic vortex is typically weaker in the one in the south due to nearby land including mountain ranges, which disturb the weather. The hole's closure was a result of the vortex splitting.
The last time a similarly strong chemical ozone depletion was observed over the Arctic was in spring 2011.
Copernicus scientist Antje Inness told Euro News the hole was a "record-breaking event".
"It is very unusual for such strong ozone depletion to occur in the northern hemisphere, but this year's polar vortex was exceptionally strong and persistent, and temperatures were low enough to allow stratospheric cloud formation for several months," he said.
"We do not know at the moment why the dynamics were so unusual this winter. I am sure that many scientists will do modelling studies to find out the reasons for this."
Earlier this month, scientists from the European Space Agency said that the rare hole covered an area about three times the size of Greenland.
CAMS said on Monday that it does not expect the same conditions to occur next year.
