Depletion of the ozone layer is caused due to:

The depletion of the ozone layer is usually caused by chlorofluorocarbons (CFCs), which are commonly known by the brand name Freon. When Freon molecules are released into the atmosphere, they will eventually reach the stratosphere. In this region, high-energy UV rays will break them down and release chlorine atoms. A single chlorine atom has the ability to destroy up to 100,000 ozone molecules by converting them to oxygen. This leads to the thinning of the ozone layer, creating holes that allow UV rays to penetrate to the earth’s surface.