R-22, commonly known as Freon, was the standard refrigerant used in most air conditioning systems for decades. Officially designated HCFC-22, it is now being phased out globally due to its environmental consequences, leading to confusion about its classification. Although R-22 is often grouped with older, banned refrigerants, its chemical structure places it in a different category. Understanding its composition is necessary to grasp why it was regulated.
Defining the Chemical Classes
R-22 is not a Chlorofluorocarbon (CFC); it belongs to the class of Hydrochlorofluorocarbons (HCFCs). The difference lies in their atomic structure, specifically the presence of a hydrogen atom. CFCs, such as the older refrigerant R-12, are composed only of Carbon, Chlorine, and Fluorine atoms. They are considered fully halogenated because every available bond on the carbon atom is occupied by a halogen atom.
HCFCs contain Carbon, Chlorine, Fluorine, and at least one Hydrogen atom. This hydrogen atom distinguishes R-22 from a true CFC. The hydrogen makes the HCFC molecule less stable, allowing it to break down lower in the atmosphere, specifically in the troposphere. This earlier breakdown significantly lowers the amount of ozone-destroying chlorine that reaches the upper atmosphere compared to persistent CFCs.
A third class, Hydrofluorocarbons (HFCs), contains Carbon, Hydrogen, and Fluorine, but no Chlorine. Since chlorine destroys stratospheric ozone, HFCs have an Ozone Depletion Potential (ODP) of zero. This distinction explains why HCFCs were initially used as an interim replacement for CFCs.
The Environmental Effects of R-22
Although R-22 is not a CFC, it was regulated and phased out because it poses two threats to the global atmosphere. The first concern is its ability to deplete the stratospheric ozone layer. R-22 has an Ozone Depletion Potential (ODP) of 0.05, meaning its ozone impact is twenty times less than the baseline CFC-11 (ODP of 1.0). However, an ODP above zero means that released R-22 molecules still release chlorine that destroys ozone when they reach the stratosphere.
The second environmental concern is R-22’s contribution to the greenhouse effect. This is measured by its Global Warming Potential (GWP), which compares the gas’s heat-trapping ability to carbon dioxide over 100 years. R-22 has a GWP of 1,810, meaning one pound traps 1,810 times more heat than carbon dioxide.
This high GWP makes R-22 a potent greenhouse gas, meaning small leaks have an outsized impact on climate change. The phase-out was driven by this dual threat: a measurable impact on the ozone layer and a substantial ability to warm the planet.
Regulatory Action and Modern Refrigerants
The global mandate to phase out R-22 and other HCFCs stems from the Montreal Protocol, an international treaty signed in 1987 to protect the ozone layer. In the U.S., the EPA implemented this phase-out through the Clean Air Act, establishing a long-term schedule for reducing HCFC production and import. This gradual process allowed the HVAC industry time to transition to compliant technologies.
The final step in this regulatory timeline occurred on January 1, 2020, when the production and import of R-22 were banned in the United States. This stopped the supply of new R-22 for servicing existing equipment. Servicing older units is now limited to using only recovered, recycled, or reclaimed refrigerant already in circulation.
This scarcity has caused the price of R-22 to increase, making repairs on older systems more expensive for consumers. The primary replacement for new equipment manufactured after 2010 is R-410A. R-410A is an HFC with an ODP of zero, but it carries a high GWP. This high GWP is now leading to regulatory action to phase out HFCs in favor of ultra-low GWP alternatives like Hydrofluoroolefins (HFOs).