2 Ozone, Refrigerants, and Environmental Impact

Ozone protection and refrigerant families

The stratospheric ozone layer absorbs much of the Sun’s harmful ultraviolet-B (UV-B) radiation. Certain stable chemicals containing chlorine or bromine can reach the stratosphere, where strong ultraviolet light breaks them down and releases atoms that catalytically destroy ozone. A chlorine atom can take part in many ozone-destroying reactions before it is removed from the atmosphere.

Lower ozone levels allow more UV-B to reach Earth’s surface. This increases risks such as skin cancer and cataracts and can harm plants, aquatic organisms, and some materials.

Refrigerant families

• CFCs (chlorofluorocarbons) contain chlorine and generally have high ozone-depletion potential. R-12 is a familiar example.

• HCFCs (hydrochlorofluorocarbons) contain chlorine but generally have lower ozone-depletion potential than CFCs. R-22 is a familiar example.

• HFCs (hydrofluorocarbons) contain no chlorine and have zero ozone-depletion potential. R-134a is an example, but zero ozone-depletion potential does not mean zero climate impact.

• HFOs (hydrofluoroolefins) are unsaturated refrigerants used in some newer alternatives. Their environmental and safety properties depend on the specific refrigerant.

Distinguishing ozone and climate measures

Ozone-depletion potential (ODP) compares a substance’s ozone-depleting effect with that of CFC-11, which is assigned an ODP of $1$. Global-warming potential (GWP) compares the warming effect of a given mass of a greenhouse gas with the same mass of carbon dioxide over a specified time period; carbon dioxide has a GWP of $1$. ODP concerns ozone depletion, whereas GWP concerns climate warming.

Direct and indirect environmental effects

A refrigerant released into the atmosphere can have a direct environmental effect. CFCs and HCFCs can deplete stratospheric ozone, and many refrigerants, including many HFCs, can trap heat and contribute to climate change. The climate effect of a leak depends on the refrigerant’s GWP and the amount released.

Refrigerant leakage can also have an indirect climate effect. Lost charge and inefficient equipment may require more energy, causing additional emissions from electricity generation.

A substitute can address one environmental problem while leaving another. HFCs, for example, have zero ODP, but some have high GWP. Refrigerant selection therefore considers ozone impact, climate impact, energy efficiency, safety, and equipment compatibility—not just one environmental measure. Section 608’s venting prohibition also covers many non-ozone-depleting substitutes, including HFCs, during covered servicing, maintenance, repair, and disposal activities.

Ozone-substance phaseouts and HFC phasedown

The Montreal Protocol and the U.S. Clean Air Act established controls on ozone-depleting substances. A phaseout of production and import does not by itself require every existing appliance to be removed from service; distinguish limits on new supply from continued operation or servicing of existing equipment.

• The United States phased out production and import of most Class I substances, including CFCs, in the 1990s. CFC production ended in 1996, subject to limited exceptions.

• U.S. production and import of new R-22 (HCFC-22) ended on January 1, 2020. Existing R-22 equipment may continue to operate and be serviced. Refrigerant for service may come from previously produced, recovered, recycled, or reclaimed supplies, subject to applicable rules.

• The phaseout of remaining HCFC production and import in the United States is scheduled for 2030, with limited exceptions.

HFCs are not ozone-depleting substances, but the American Innovation and Manufacturing (AIM) Act phases down their production and consumption because of their climate impact. As of 2026, the U.S. allowance cap is $60\%$ of the historical baseline for 2024–2028. It falls to $30\%$ for 2029–2033, $20\%$ for 2034–2035, and $15\%$ from 2036 onward. This is a phasedown of production and consumption, not a blanket order to stop using every HFC or immediately replace all existing HFC equipment. Separate rules may restrict particular refrigerants in particular new products or sectors.

Blends, glide, and fractionation

A refrigerant blend is a mixture of two or more refrigerant components. Components may have different boiling points and environmental properties, so a blend’s overall ODP and GWP depend on its composition.

A zeotropic blend changes composition between liquid and vapor as it boils or condenses. Its temperature may change during a phase change at a given pressure; this difference is called temperature glide. If components leak at different rates, the composition of the remaining refrigerant can shift. This is fractionation.

An azeotropic blend behaves more like a single refrigerant during boiling and condensation, with little or no temperature glide and much less tendency to fractionate during a leak.

Because zeotropic blends can fractionate, they are generally withdrawn from the supply cylinder as liquid when charging, following the equipment manufacturer’s instructions. Introducing liquid into a running system requires the correct procedure and equipment; avoid sending liquid directly into a compressor. Never mix different refrigerants in a recovery cylinder or assume that an alternative is a universal “drop-in” replacement.

Recovering, recycling, and reclaiming

Recover, recycle, and reclaim refer to different refrigerant-handling processes.

• Recover: Remove refrigerant from an appliance and store it in an external container. The refrigerant need not be cleaned.

• Recycle: Clean recovered refrigerant for reuse, typically by oil separation and filtration or drying. This is not the same as reclamation.

• Reclaim: Reprocess refrigerant to the required purity standard and verify it by analysis. Under EPA rules, recovered refrigerant generally must be reclaimed by an EPA-certified reclaimer before resale.