Use of Ozone-Depleting Substances as Process Agents
Under Title VI of the Clean Air Act (CAA) and implementing regulations, ozone-depleting substances (ODS) are regulated as class I or class II controlled substances. Class I controlled substances, i.e., chlorofluorocarbons (CFCs), halons, carbon tetrachloride, methyl chloroform, methyl bromide, and hydrobromofluorocarbons, have an ozone depletion potential (ODP) of 0.2 or higher and were phased out ahead of class II controlled substances. Class II controlled substances have ODPs less than 0.2 and are all hydrochlorofluorocarbons (HCFCs), which were developed as transitional substitutes for class I ODS. While existing regulations allow for limited production and consumption of two HCFCs (HCFC-123 and HCFC-124) until 2030, all others have been phased out in the United States.
In line with decisions under the Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) that allow for the continued use of ODS as process agents under specified situations, the Agency annually requests, collects, and reviews information on these process agent uses, and reports a summary of this information to the Montreal Protocol’s Ozone Secretariat on behalf of the United States.
An ODS process agent is a controlled substance used to form the environment for a chemical reaction or inhibit an unintended chemical reaction (e.g., use as a solvent, catalyst, or stabilizer) where the controlled substance is not consumed in the reaction, but is removed or recycled back into the process and where no more than trace quantities remain in the final product. A feedstock, in contrast, is consumed during the reaction. The term process agent includes, but is not limited to: carbon tetrachloride used in the elimination of nitrogen trichloride in chlor-alkali production, carbon tetrachloride used in the recovery of chlorine by tail gas absorption from chlor-alkali production, CFC-11 used in the production of synthetic fiber sheet, bromochloromethane used in the bromination of a styrenic polymer, and CFC-113 used in the production of high modulus polyethylene fiber.
This rulemaking establishes specific recordkeeping and reporting requirements for uses of ODS as process agents and related definitions.
Additional information on the final rule: