The ozone hole over the South Pole has reached its biggest size of the year, and it was continental big.

The depletion of the ozone layer in the stratosphere over Antarctica hit 10 million square miles on September 21, making it the 12 largest hole since measurements began in 1979. This is bigger than the size of North America and about the size of Africa.

The ozone hole peaks during the South Pole’s late winter and early spring, when the stratosphere temperatures are at its coldest and the reaction between human-made chloride- and bromide-containing chemicals and ozone occurs.

The 1987 Montreal Protocol and amendments have banned the manufacturing of chlorofluorocarbon (CFC). These chemicals were used as refrigerants, aerosol propellant, solvents, and fire suppression.

The ozone hole size has been decreasing over the past 5 to 10 years with the reduction of CFC in the atmosphere. It is estimated that CFC can linger in the atmosphere for 50 to 100 years.

Scientists believe this year’s unusually big ozone hole is due to the violent January 2022 eruption of Hunga Tonga-Hunga Ha’apai volcano. It sent water vapour high into the atmosphere, which likely contributed to increased reactions between CFC and ozone.

The ozone layer absorbs UV radiation from the sun, providing protection against sunburns, skin cancer, and cataracts.

Our UV index provides the latest information about the sun’s threat directly on our main forecast page.