Air Quality: Revision to Definition of Volatile Organic Compounds— Exclusion of trans-1,3,3,3- tetrafluoropropene

This action revises the EPA’s definition of volatile organic compounds (VOCs) under the Clean Air Act (CAA). This revision adds trans1,3,3,3-tetrafluoropropene (also known as HFO-1234ze) to the list of compounds excluded from the definition of VOC on the basis that this compound makes a negligible contribution to tropospheric ozone formation. As a result, if you are subject to certain federal regulations limiting emissions of VOCs, your emissions of HFO-1234ze may not be regulated for some purposes. This action may also affect whether HFO-1234ze is considered a VOC for state regulatory purposes, depending on whether the state relies on the EPA’s definition of VOC.