The researchers studied the Arctic ozone layer in the winter-spring of 2020. They used data and models to analyze how ozone levels changed in the polar vortex. They found that in 2019-2020, there was a significant loss of ozone at high altitudes, exceeding previous years. The total ozone depletion inside the vortex was over 150 Dobson Units, matching a record low from a decade ago. Both natural processes and chemical reactions contributed to the ozone loss, with different impacts in the western and eastern hemispheres. Chemical reactions played a significant role in the east, while dynamics were more important in the west. This study helps us understand how ozone depletion occurs in the Arctic and how different factors contribute to this process.