Regarding ozone depletion, which statement is true about HFCs?

• A. They are proven to deplete the ozone layer.
• B. They do not deplete the ozone layer.
• C. They only deplete ozone in the upper atmosphere.
• D. They deplete ozone when exposed to light.

Answer: (B)

Ozone depletion is driven by chlorine- and bromine-containing halogens released in the stratosphere, which initiate catalytic cycles that destroy ozone. HFCs contain hydrogen, carbon, and fluorine and do not have chlorine or bromine. When HFCs break down in the atmosphere, they don’t generate the halogen radicals that drive ozone loss, so they do not participate in the ozone-destroying processes. That’s why they are considered not to deplete the ozone layer, even though they are potent greenhouse gases with high global warming potential and are regulated for climate reasons. The other statements would imply a mechanism that HFCs don’t possess—either releasing ozone-destroying halogens or requiring a specific photolytic condition—so they don’t apply.