Pollutants and Schedules for Phaseout

In 1987, most industrialized countries agreed, under the Montreal Protocol, to revert to 1986 production and consumption levels of certain ozone-depleting substances. The Montreal Protocol was later amended to specify a phase-out schedule for the ozone-depleting chemicals that were subsequently accelerated.

The CAAA divided the ozone-depleting chemicals into two classes. Class I chemicals include specified chlorofluorocarbons (CFCs), halons, 1,1,1 trichloro-ethane (or methyl chloroform), and carbon tetrachloride. Class II chemicals are mostly hydrochlorofluorocarbons (HCFCs).

Class I Ozone-Depleting Substances

CFCs are the primary component of many common electric air conditioning refrigerants. These refrigerants are commonly referred to by their trade name and listed by trade number. CFC-based refrigerants, such as CFC-11 and CFC-12, were the leading refrigerants for most large systems. Because of their role in the destruction of stratospheric ozone, the EPA and the United Nations Environment Programme (UNEP) have restricted the use and production of CFCs. Venting of refrigerants to the environment became illegal in 1992. The final regulatory requirements limiting the production and consumption of ozone-depleting substances were issued by the EPA in December, 1993 (58 FR 65018 and 58 FR 69235). Consistent with the Montreal Protocol and other international treaties, the regulations required a complete phase-out of CFCs by 1996. Since that date, the only available CFCs are those that have been reclaimed from equipment that has either been retired or converted to a non-CFC refrigerant. Two major types of CFC replacements are HCFCs and hydro (HFCs).

HFCs differ from CFCs and HCFCs in that they contain no ozone depleting chlorine and have lower global warming potential (GWP) than CFCs. As a result, there are no current phase-out dates or production bans for HFCs, nor is one anticipated. The most prominent HFC, R-134a, was developed to replace CFC refrigerant R-12, which is used in equipment such as positive pressure centrifugal compressors, home refrigerators, and automobile air conditioners. HCFCs are addressed below in the discussion of Class II Ozone-Depleting Substances.

Halon, another Class I substance, is used in fire suppression and control equipment and was scheduled for phase-out by 1994. Halon production and importation in the United States ended on December 31 1993. In 1996, 1,1,1 trichloroethane or methyl chloroform, which was used extensively as a cleaning solvent, was phased out. Carbon tetrachloride, which is used primarily as a feedstock in the production of CFC-11 and CFC-12, was also phased-out in 1996.

Class II Ozone-Depleting Substances

HCFCs comprise most of the Class II substances and are used throughout the industry as substitutes for CFCs. Because HCFCs have hydrogen atoms included in their molecular structure, they have shorter atmospheric lifetimes and do less damage to the ozone than do CFCs. HCFC-22 is the most common refrigerant used in residential air conditioners. The CAAA freezes production and consumption of HCFC-22 by January 1, 2020. HCFC-123 has recently become a commonly used replacement for CFC-11. The law freezes productions of HCFCs by 2015 and eliminates their use entirely by

2030. HCFCs are referred to as bridge refrigerants because they will remain in use for several decades until current and newly developed alternatives take over the market.

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