Effects of Improper Handling of Refrigerants on the Ozone Layer and Climate
Domain 4 - Effects of improper handling of refrigerants on the ozone layer and climate. This domain tests the science behind the rules: which refrigerants attack stratospheric ozone, which drive climate change, how those two harms are measured, and what an emitted pound of refrigerant actually means in comparable terms.
Ozone chemistry
- Stratospheric ozone absorbs harmful UV-B. Chlorine and bromine radicals catalytically destroy ozone: a single chlorine atom can cycle through thousands of ozone-destroying reactions - commonly cited as on the order of 100,000 ozone molecules - before it leaves the stratosphere.
- CFCs are so stable that they persist for decades (CFC-12 has an atmospheric lifetime near 100 years), survive transport to the stratosphere, and only then break down under UV light to release chlorine.
- Ozone Depletion Potential (ODP) is scaled to CFC-12 = 1.0. HCFC-22 is roughly 0.055. HFC-134a and HFO-1234yf contain no chlorine and have an ODP of 0. HFCs do not deplete ozone.
Climate effects
- Global Warming Potential (GWP), 100-year horizon, CO2 = 1: CFC-12 ≈ 10,900; HFC-134a ≈ 1,430; HFO-1234yf ≈ 4.
- Direct emissions come from leaks and venting; indirect emissions come from lost efficiency - a system with air, moisture, or an undercharge burns more fuel to deliver the same cooling.
- Policy track: the Montreal Protocol (1987) phased out CFCs, with the U.S. CFC phaseout taking effect January 1, 1996; the 2016 Kigali Amendment extends the treaty to HFCs, and the 2020 AIM Act implements an HFC phase-down domestically.
Worked example
One pound of CFC-12 vented: 0.4536 kg × 10,900 = about 4,944 kg CO2-equivalent, or roughly 4.9 metric tons - comparable to driving a typical gasoline car about 12,000 miles. The same mass of HFC-134a: 0.4536 × 1,430 ≈ 649 kg, about 0.65 metric tons. The same mass of HFO-1234yf: 0.4536 × 4 ≈ 1.8 kg. The reasoning matters more than the arithmetic: mass alone says nothing about impact; you must multiply by the refrigerant's GWP.
Traps that cost marks
- Claiming HFCs deplete ozone because they are refrigerants - they are potent greenhouse gases, not ozone destroyers.
- Confusing ODP and GWP scales, or forgetting CFC-12 is the ODP reference value.
- Assuming low-GWP R-1234yf may be vented. The venting prohibition still applies, and R-1234yf is an A2L mildly flammable refrigerant.
- Ignoring flame exposure: refrigerant drawn through a flame or hot surface decomposes into hydrogen fluoride and carbonyl fluoride.