This year’s ozone hole was the seventh largest in 48 years, NASA says

The hole in the ozone layer over Antarctica was the seventh largest in 48 years of satellite monitoring this year, NASA’s Earth Observatory said on 9 November. However, ozone levels inside it did not fall as low as in other large holes on record.

NASA measures the hole by its average size from 7 September to 13 October, the peak season for ozone loss. This year the hole reached its largest extent on 18 September. Scientists say an unusually strong polar vortex, a ring of cold winds around Antarctica, created ideal conditions for ozone loss over a wide area.

Why it matters

The ozone layer, high in the atmosphere, absorbs ultraviolet light from the Sun. That light damages DNA in plants and animals and causes sunburn and skin cancer in people.

Scientists call any area where ozone falls below 220 Dobson units, the standard measure, part of the “hole”. The deepest hole on record came in 1994, when levels fell to 73 units on 30 September. The largest by area came in 2006.

The damage was caused mainly by chlorofluorocarbons, or CFCs, chemicals once used in refrigerators and aerosol sprays. The Montreal Protocol, an international treaty, has phased them out. Scientists expect the ozone layer to return to its 1980 levels in the 2070s.