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How did chlorofluorocarbons contribute to ozone depletion?

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Wispy cirrus clouds stretch across a bright blue sky above trees and a river at Pinawa Dam Provincial Park in Manitoba, Canada, with sunlight illuminating the scene. — Atmosphere The atmospheres of planets in the solar system are composed of various gases, particulates, and liquids. They are also dynamic places that redistribute heat and other forms of energy. On Earth, the atmosphere provides critical ingredients for living things. Here, feathery cirrus clouds drift across the deep blue sky over Pinawa Dam Provincial Park, near Pinawa, Manitoba, Canada.

Chlorofluorocarbons (CFCs) contribute to ozone depletion by acting as a source of chlorine in the stratosphere.1

When CFCs are released into the atmosphere, they accumulate in the stratosphere, where they are exposed to solar ultraviolet radiation. This radiation causes the CFC molecules to dissociate, liberating highly reactive chlorine atoms.12

Once freed, these chlorine atoms initiate a destructive catalytic cycle. They react with ozone (O₃) molecules by stripping away one of the three oxygen atoms, effectively breaking the ozone molecule apart and converting it into oxygen gas (O₂). A single chlorine atom can facilitate the destruction of thousands of ozone molecules in this manner. This process reduces the concentration of the ozone layer, which is essential for shielding Earth from harmful UV radiation. International efforts, such as the Montreal Protocol, have successfully phased out the production of these chemicals to allow the ozone layer to recover.1234