SNAP was established under Section 612 of the Clean Air Act to identify and evaluate substitutes for ozone-depleting substances. The program looks at overall risks to human health and the environment of existing and new substitutes, publishes lists and promotes the use of acceptable substances, and provides the public with information. Learn more about the SNAP program.
Class I Substance: one of several groups of chemicals with an ozone-depletion potential of 0.2 or higher
Class I substances listed in the Clean Air Act (CAA) include CFCs, halons, carbon tetrachloride, and methyl chloroform. EPA later added HBFCs and methyl bromide to the list by regulation. A table of class I substances shows their lifetime ODPs, GWPs, and CAS numbers.
Class II Substance: a chemical with an ozone-depletion potential of less than 0.2
Currently, all of the HCFCs are class II substances. Lists of class II substances with their ODPs, GWPs, and CAS numbers are available.