Air Quality: Revision to the Regulatory Definition of Volatile Organic Compounds – Exclusion of Cis-1,1,1,4,4,4-hexafluorobut-2-ene (also Known as Hfo-1336mzz-z)

FACT SHEET

Air Quality: Revision to the Regulatory Definition of Volatile Organic Compounds -
Exclusion of cis-l,l?l?4,4,4-hexafluorobut-2-ene (also known as HFO-1336mzz-Z)

ACTION

• On November 16, 2018, the U.S. Environmental Protection Agency (EPA) issued a final
rule revising the regulatory definition of volatile organic compounds (VOC) under the
Clean Air Act. This action will add cis-1,1,1,4,4,4-hexafluorobut-2-ene (also known as
HFO-1336mzz-Z; CAS RN 692-49-9) 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.

• Some VOCs contribute significantly to the formation of ground-level ozone. Exposure to
ozone can cause serious respiratory illness. Due to its low photochemical reactivity,
HFO-1336mzz-Z is considered to be negligibly reactive in the formation of ground-level
ozone and is not expected to contribute to violations of the national ambient air quality
standards (NAAQS).

• This action is based on consideration of HFO-1336mzz-Z's negligible contribution to
ground-level ozone and the low likelihood of risk to human health and the environment
associated with its use.

• This final action will allow, but does not require, states to exclude from control emissions
of HFO-1336mzz-Z in State Implementation Plans (SIP) designed to meet the ground-
level ozone standards. This enables industry to use HFO-1336mzz-Z with fewer
restrictions.

• HFO-1336mzz-Z may be used in a variety of applications as a replacement for foam
expansion or blowing agents most of which have higher global warming potential (GWP)
(>700 GWP) and are used in the production of polyurethane rigid insulating foams. It is
also a new developmental refrigerant for use as a potential working fluid for Organic
Rankine Cycles (ORC)1 used to produce energy.

1 The Organic Rankine Cycle (ORC) is named for its use of an organic, high molecular mass
fluid with a liquid-vapor phase change, or boiling point, occurring at a lower temperature than
the water-steam phase change. The fluid allows Rankine cycle heat recovery from lower
temperature sources such as biomass combustion, industrial waste heat, geothermal heat, solar
ponds etc. The low-temperature heat is converted into useful work, that can itself be converted
into electricity.

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• HFO-1336mzz-Z as a foam blowing agent and a refrigerant 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.

• This final rule will be effective 60 days after publication in the Federal Register.

BACKGROUND

• A compound may be excluded as a VOC as a result of public petitions and scientific data
that demonstrate its negligible effect on the formation of ground-level ozone. Since 1977,
EPA has removed 62 specific compounds or classes of compounds from the list of VOC
that contribute to ozone formation.

• DuPont Chemicals & Fluoro-products (DuPont)/Chemours submitted a petition to the
EPA on February 4, 2014, requesting that cis-1,1,1,4,4,4-hexafluorobut-2-ene (also
known as HFO-1336mzz-Z; CAS RN 692-49-9) be exempted from the regulatory
definition of VOC. The petition was based on the argument that HFO-1336mzz-Z has
low reactivity relative to ethane.

• EPA has carefully reviewed all available scientific data and in response to received
comments, continues to find HFO-1336mzz-Z eligible for exclusion from regulation as a
VOC.

FOR MORE INFORMATON

• Interested parties can download the action and other materials from EPA's Web site on
the Internet under Recent Actions at the following address: https://www.epa.gov/ozone-
pollution/ozone-volatile-organic-compound-voc-exemptions-rules.

¦ To view the final rule and any background information related to the rule (use Docket
ID No. EPA-HQ-OAR-2017-0175), go to http://www.regulations.gov.

¦ EPA's electronic public docket and comment system at

https://www.regulations.gov.

¦ The EPA Docket Center's Public Reading Room (for hard copies).

¦ The Public Reading Room is located at EPA Headquarters, Room Number 3334 in
EPA WJC West Building, 1301 Constitution Avenue, NW, Washington, DC. Hours
of operation are 8:30 a.m. to 4:30 p.m. eastern standard time, Monday through Friday,
excluding federal holidays. The telephone number for the Public Reading Room is
(202) 566-1744, and the telephone number for the Air and Radiation Docket is (202)
566-1742.

o You will have to show photo identification, pass through a metal detector, and
sign the EPA visitor log. Any materials you bring with you will be processed

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through an X-ray machine as well. You will be provided a badge that must be
visible at all times.

¦ For further information about these actions, contact Dr. Souad Benromdhane of
EPA's Office of Air Quality Planning and Standards, at (919) 541-4359 or by email
at benromdhane.souad@epa.gov.

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