Which refrigerant is commonly phased out due to environmental regulations?

R-22, also known as HCFC-22, has been widely phased out due to its harmful effects on the ozone layer. Under the Montreal Protocol and subsequent regulations, the use and production of R-22 have been aggressively reduced since it is a hydrochlorofluorocarbon. This refrigerant's phase-out is part of a global effort to eliminate substances that deplete the ozone layer.

The timeline for R-22 indicates a complete ban on its production or import in the United States as of January 1, 2020. While R-12 was also phased out due to its high ozone depletion potential, R-22's phase-out is more recent and relevant to current regulatory standards. Other refrigerants like R-134a and R-410A are subject to different regulations and have been developed as alternatives with lower environmental impact, but R-22 remains a focal point in discussions of refrigerant phase-outs due to its regulation status and past use in residential and commercial cooling systems.