TADEAS:
Ozone hole three times the size of Greenland opens over the North Pole | Live Science
https://www.livescience.com/amp/largest-ozone-hole-arctic-north-pole.html
The Antarctic ozone hole opens every year due to the combination of frigid temperatures and man-made pollution. When temperatures plummet at the start of Antarctica's winter, high-altitude clouds form over the South Pole. Industrial chemical pollutants, including chlorine and bromine, trigger reactions in these clouds that eat away at the surrounding ozone gas.
The Arctic, which has more variable temperatures, doesn't usually see the same ozone-depleting conditions, the researchers said. But this year, powerful winds trapped cold air in a "polar vortex" above the Arctic. That led to colder temperatures and more high-altitude clouds than normal. Hence, North Pole ozone-depletion began.