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Ozone depletion potential (ODP) compares chemicals to which compound, defined as 1.0?

CFC-11 is the yardstick: its ODP is defined as 1.0.

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  1. R-22
  2. R-134a
  3. CFC-11 ✔

Why: ODP compares a chemical's effect on ozone to the same mass of CFC-11. A bigger number means more ozone damage. A zero means none.

Huh, didn't know that: Halons have ODPs ranging up to 10, far worse than CFC-11.

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References

Answer: CFC-11. ODP compares a chemical's effect on ozone to the same mass of CFC-11. A bigger number means more ozone damage. A zero means none.

  1. Ozone-Depleting Substances, US EPA www.epa.gov/ozone-layer-protection/ozone-depleting-substances
    Thus, the ODP of CFC-11 is defined to be 1.0.
    Checked 2026-10-10.
  2. Section 608 Technician Certification Test Topics, US EPA www.epa.gov/section608/section-608-technician-certification-test-topics
    HCFCs have ozone depletion potentials (ODPs) ranging from 0.01 to 0.1
    Checked 2026-10-10.

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