Which refrigerant chemicals are responsible for the destruction of the ozone layer?

• A. CO2 and methane
• B. Halons and ammonia
• C. Water vapor
• D. CFCs and HCFCs

Answer: (D)

Ozone depletion happens when chlorine- and bromine-containing compounds reach the stratosphere and are broken down by UV light, releasing halogen radicals that catalytically destroy ozone. CFCs and HCFCs are refrigerants that release chlorine when they break down, and that chlorine drives ozone loss through repeated cycles converting O3 to O2. HCFCs do so to a lesser extent than CFCs because they break down faster, but they still contribute to the problem. The other options don’t fit as well: CO2 and methane are mainly climate forcers, not the primary ozone-depleting agents in refrigerants; water vapor isn’t a refrigerant chemical responsible for ozone destruction; halons do deplete ozone but aren’t the standard refrigerants emphasized here, and ammonia isn’t a major ozone-depleting agent.