In 2011, the Arctic experienced a record loss of ozone due to extremely cold temperatures and a stable polar vortex. This led to high levels of chlorine activation and chemical destruction of ozone. Unlike previous years, the polar vortex remained cold well into April, prolonging the ozone loss period. Measurements from various instruments confirmed this record loss, which was compared to ozone losses in the Antarctic. The study focused on understanding the extent and evolution of this unprecedented Arctic ozone depletion event.