Ozone is a colourless gas present in the stratosphere and is known to have protected life on Earth from the effects of ultraviolet rays. The ozone layer mainly blocks UV-B rays, which are famous for increasing the risks of skin cancer, cataracts, and a suppressed immune system.

What is the ozone hole?

The phenomenon we refer to as the “ozone hole” is actually an ozone depletion in the sky. Every spring in Antarctica, so from September through November, chemical processes destroy over 50% of the total amount of the atmospheric ozone.

During the last 20 years, the “ozone hole” increased in size and in length of existence as nowadays the hole is present from August to December. This means that it allows more harmful rays to reach the Earth and therefore the population.

What causes the ozone hole?

Ready to hear some unpronounceable words? A group of manufactured chemicals containing chlorine and/or bromine, called “ozone-depleting substances” or ODS, have been proven to be destroying the stratospheric ozone. The main ODS are called chlorofluorocarbons, or CFCs, and are the source of 80% of the ozone depletion. Before 1995, they were used as coolants in refrigerators, freezers or air conditioning systems.

In 1987, thanks to the Montreal protocol, the use of CFCs was banned in 197 countries. To replace them, Hydrofluorocarbons, or HFCs, are being developed. These new chemicals do not deplete ozone but they are strong greenhouse gases, which are known to play a major role in Global Warming. However, HFCs are still considered to be the best alternative to CFCs.

The ozone hole today.

Today the ozone hole seems to be on the road to recovery. Indeed, the levels of ozone-depleting substances have slowly decreased since the Montreal protocol. Thanks to that, the peak size of this year’s ozone hole was smaller than holes observed in the past years. According to the NASA, simulations predict that the Antarctic ozone layer should recover around 2040.

Scientists are now looking for other reasons for these improvements, such as a link between the rising of temperatures in the Stratosphere, an upper layer of the atmosphere, and the increase in ozone.