OZONE DEPLETION

Ozone is formed when heat and sunlight cause chemical reactions between oxides of nitrogen (NOX ) and Volatile Organic Compounds (VOC), which are also known as Hydrocarbons. The ozone layer filters out most of the sun's harmful UV radiation and is therefore crucial to life on Earth. The chlorine atom and one of the oxygen atoms of ozone combine, leaving behind diatomic, or molecular, oxygen.

https://ozonewatch.gsfc.nasa.gov/facts/hole_SH.html

When a free oxygen atom contacts this chlorine-oxygen compound, the two oxygen atoms combine to form molecular oxygen, and the chlorine goes off to devastate more ozone molecules.

Ozone is constantly being formed and destroyed, but the total amount of ozone in the atmosphere should essentially remain at a stable number.