Proposed Revision to the Regulatory Definition of Volatile Organic Compounds

On April 21,2022, the Administrator signed a proposed revision to add trans-1,1,1,4,4,4-hexafluorobut-2-ene (also known as HFO-1336mzz-E; CAS RN 66711-86-2) to the list of compounds excluded from the regulatory definition of volatile organic compound (VOC) because it makes a negligible contribution to ground-level ozone formation.

HFO-1336mzz(E) may be used in a variety of applications in foam expansion or blowing agents where it has significant performance and energy-saving advantages. It can serve as a replacement for several compounds with higher global warming potential.  It also has a lower stratospheric ozone depletion potential than other alternatives, and based on the available toxicity data, it is less harmful compared with other chemicals used for the same purpose. EPA will accept comment on this proposal for 60 days after publication in the Federal Register.

For more information and a prepublication version of the proposed revision, visit: