The concentration of ozone-depleting substances in the atmosphere has reduced to reach a significant milestone this year.
Levels of ozone-depleting substances (ODSs) in 2022 are back to those observed in 1980 before ozone depletion was significant.
However, the pace of reduction in ODSs over Antarctica, which experiences a large ozone hole in spring, has been slower.
National Oceanic and Atmospheric Administration (NOAA) Ozone Depleting Gas Index for the Antarctic has fallen 26 per cent from peak values in the 1990s, with recovery of the Antarctic ozone layer projected to occur sometime around 2070.
What is Ozone hole?
An ozone hole is the thinning of the ozone layer boosted in size by colder temperatures.
As the temperature high up in the stratosphere starts to rise, ozone depletion slows, the polar vortex weakens and breaks down.
By the end of December, ozone levels return to normal. This time around, however, the process took longer.
The formation of ozone hole in the Antarctic has been an annual occurrence and has been recorded for the last 40 years.
Human-made chemicals migrate into the stratosphere and accumulate inside the polar vortex.
It begins to shrink in size as warmer temperatures dominate
Ozone is a special form of oxygen, made up of three oxygen atoms rather than the usual two oxygen atoms.
It usually forms when some type of radiation or electrical discharge separates the two atoms in an oxygen molecule (O2), which can then individually recombine with other oxygen molecules to form ozone (O3).
The science behind ozone depletion
Ozone depletion occurs when chlorofluorocarbons (CFCs) and halons (gases formerly found in aerosol spray cans and refrigerants) are released into the atmosphere.
Ozone sits in the upper atmosphere and absorbs ultraviolet radiaton, another type of solar energy that's harmful to humans, animals and plants.
CFCs and halons cause chemical reactions that break down ozone molecules, reducing ozone's ultraviolet radiation-absorbing capacity.