Which of the following is not classified as an ozone-depleting substance?

Hydrofluorocarbons (HFCs) are classified as substances that do not deplete the ozone layer. This makes them a significant alternative when considering refrigerants that minimize environmental impact, particularly in comparison to other substances such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), both of which contain chlorine and have been shown to contribute to ozone depletion.

Chlorinated solvents are another category of substances that may also pose risks to the ozone layer, depending on their chemical composition, but HFCs do not contain chlorine and thus do not have the same harmful effects on ozone as CFCs and HCFCs. This characteristic is crucial in regulatory contexts, especially with the phasedown initiatives targeting substances that harm the ozone layer. HFCs have been adopted under the Kigali Amendment to the Montreal Protocol as part of a global effort to reduce these potent greenhouse gases while avoiding ozone depletion.