Which refrigerants have been phased out due to their harmful effects on the ozone layer?

• A. CFCs and HCFCs
• B. HFCs and HFOs
• C. Propane and butane
• D. Ammonia only

Answer: (A)

CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons) have been phased out primarily due to their detrimental impact on the ozone layer. CFCs were widely used in refrigeration, air conditioning, and aerosol propellants, but research revealed that they release chlorine when they reach the stratosphere, leading to ozone depletion. HCFCs were introduced as transitional substitutes for CFCs because they have a lower ozone-depleting potential; however, they still contribute to ozone layer damage and are being phased out under international agreements like the Montreal Protocol.

In contrast, HFCs (hydrofluorocarbons) and HFOs (hydrofluoroolefins), while they have a low potential to harm the ozone layer, are being scrutinized and phased down due to their high global warming potential. Propane and butane are hydrocarbons that are not linked to ozone depletion; instead, they are considered more environmentally friendly alternatives for certain applications. Ammonia, while toxic and requiring careful handling, does not harm the ozone layer. This context highlights why the phasing out of CFCs and HCFCs is crucial for the protection of the