# Air Quality: Revision to the Regulatory Definition of Volatile Organic Compounds-Exclusion of cis-1,1,1,4,4,4-hexafluorobut-2-ene (HFO-1336mzz-Z)
> **Rule** · Final rule. · Published 2018-11-28 · Effective 2019-01-28 · 83 FR 61127
## Document
- **Document number:** 2018-25891
- **Category:** air-emissions
- **Federal Register citation:** 83 FR 61127
- **CFR reference:** 40 CFR 51
- **Publication date:** 2018-11-28
- **Effective date:** 2019-01-28
- **EPA docket:** EPA-HQ-OAR-2017-0175
## Abstract

On May 1, 2018, the U.S. Environmental Protection Agency (EPA) published a proposed rule seeking comments in response to a petition requesting the revision of the EPA's regulatory definition of volatile organic compounds (VOC) to exempt cis-1,1,1,4,4,4-hexafluorobut-2-ene (also known as HFO-1336mzz-Z; CAS number 692-49-9). The EPA is now taking final action to revise the regulatory definition of VOC under the Clean Air Act (CAA). This final action adds HFO-1336mzz-Z to the list of compounds excluded from the regulatory definition of VOC on the basis that this compound makes a negligible contribution to tropospheric ozone (O3) formation.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2018/11/28/2018-25891/air-quality-revision-to-the-regulatory-definition-of-volatile-organic-compounds-exclusion-of)
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