Which refrigerant is known to deplete the ozone layer?

R-12, also known as dichlorodifluoromethane, is known to deplete the ozone layer due to its chlorine content and its ability to release chlorine atoms in the stratosphere when exposed to ultraviolet radiation. The chemical structure of R-12 includes two chlorine atoms, and when it breaks down in the atmosphere, these chlorine atoms can catalytically destroy ozone molecules, leading to ozone depletion. This property led to the phase-out of R-12 under the Montreal Protocol, an international treaty aimed at protecting the ozone layer by reducing the production and consumption of substances responsible for ozone depletion.

The other refrigerants mentioned have different properties. R-22, while a hydrochlorofluorocarbon (HCFC), also has ozone-depleting potential but to a lesser extent compared to R-12. R-134a is a hydrofluorocarbon (HFC) that does not contain chlorine and has no ozone depletion potential. R-410A, also an HFC, is designed to be environmentally friendly and lacks ozone-depleting properties as well. Therefore, R-12 is distinctly recognized for its impact on the ozone layer.