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.
