3 Environmental Effects and Refrigerant Policy
Understand how refrigerants affect ozone and climate, how ODP and GWP compare those effects, and how policies, alternatives, safety, and refrigerant management shape lower-impact choices.
Two distinct environmental effects
Refrigerants can affect both the stratospheric ozone layer and climate, but these are distinct environmental effects. Ozone depletion occurs when chemicals containing chlorine or bromine reach the stratosphere and contribute to ozone destruction. Ozone loss allows more harmful ultraviolet radiation to reach Earth’s surface.
Global warming occurs when greenhouse gases trap heat in the atmosphere. CFCs such as R-12 and HCFCs such as R-22 can deplete ozone. HFCs such as R-134a and R-410A do not deplete ozone, but many can have a strong warming effect if released. Electricity used to operate cooling equipment also contributes to climate impacts.
A refrigerant can therefore have zero ozone-depletion potential but high global-warming potential. Replacing an ozone-depleting refrigerant does not automatically solve the climate problem.
Comparing ODP and GWP
compares a substance’s ozone-depleting effect with that of CFC-11, assigned an ODP of . An ODP of means no ozone-depleting effect under this metric; an ODP above indicates some potential for depletion.
compares the warming effect of a mass of gas with that of the same mass of carbon dioxide over a specified time horizon, commonly years. Carbon dioxide is assigned a GWP of . For example, a GWP of means that, on the stated -year basis, emitting of that gas has a warming effect equivalent to of carbon dioxide. NOAA’s assessment gives HFC-134a a -year GWP of and an ODP of .
These metrics help compare environmental effects, but they do not determine refrigerant choice by themselves. Published GWP values can vary with the scientific assessment used, so compare values calculated on the same basis or use the applicable regulatory list. ODP and GWP do not capture every real-world effect, including equipment energy efficiency, refrigerant leakage, and emissions during manufacture and disposal.
Phaseouts and transition policies
The , adopted in , established international controls to phase out ozone-depleting substances. In the United States, CFCs and other Class I substances have been phased out, with limited exceptions. New production and import of most HCFCs, including R-22, were phased out as of , although existing equipment may still contain HCFC refrigerant.
HFCs were widely adopted as substitutes because they do not deplete ozone. Because many HFCs have high GWPs, the to the established a global, stepwise of HFC production and consumption, with different schedules for country groups.
The directs EPA to phase down HFC production and consumption by from historic baseline levels by . It also authorizes sector-specific restrictions that support transitions to alternatives, as well as measures to manage HFCs and reduce releases.
Under EPA’s , whether a substitute is acceptable can depend on its particular use and any stated conditions. A refrigerant is not automatically approved for every type of equipment.
Alternatives and application tradeoffs
Options include lower-GWP HFC blends, HFOs, carbon dioxide (R-744), ammonia (R-717), and hydrocarbons such as propane (R-290). Many of these options have zero or very low ODP and lower GWP than the high-GWP refrigerants they may replace. Their suitability depends on the equipment and application.
Environmental performance is only one part of the choice. Alternatives can differ in flammability, toxicity, operating pressure, energy efficiency, and required system design. Propane is flammable, CO₂ systems operate at high pressures, and ammonia requires safeguards appropriate to its hazards. EPA’s SNAP listings specify acceptable uses and conditions, and some listings are limited to particular applications.
A or restriction does not necessarily mean that every existing system must be replaced immediately. Rules can differ by refrigerant, equipment type, and activity. Check current requirements for the specific application, and do not treat an alternative as a drop-in replacement unless the equipment manufacturer and applicable rules permit it.
Reducing releases and overall impact
Refrigerant leakage and releases during service and disposal contribute to environmental impact. Even a low-GWP refrigerant can cause harm if it escapes, while efficient equipment can reduce indirect emissions from electricity use.
Reducing impact therefore involves more than selecting a refrigerant: refrigerant choice, safe system design, leak prevention, and proper end-of-life management work together.