Final Amendments to Air Toxics Standards for Stationary Combustion Turbines

Fact Sheet

ACTION

•	On January, 31, 2020, the U.S. Environmental Protection Agency (EPA) finalized
amendments the 2004 National Emission Standards for Hazardous Air Pollutants
(NESHAP) for Stationary Combustion Turbines located at major sources of hazardous air
pollutant emissions.

•	Hazardous air pollutants, also known as toxic air pollutants or air toxics, are known or
suspected to cause cancer or other serious health effects or adverse environmental
effects.

•	Following a residual risk and technology review (RTR) conducted under the Clean Air Act
(CAA), EPA determined that risks from the source category are acceptable and that no
new cost-effective controls are available. The Agency is not making any changes to the
standards based on the results of the RTR.

•	EPA is, however, finalizing minor amendments to enhance the effectiveness of the
standards by improving compliance and implementation. Specifically, EPA is:

o revising requirements for periods of startup, shutdown and malfunction (SSM) to

be consistent with recent court decisions; and
o requiring electronic reporting of performance test results and compliance
reports.

RESIDUAL RISK ASSESSMENT

•	The CAA requires EPA to assess the risk remaining after application of the final air toxics
emissions standard. This is known as a residual risk assessment.

•	Based on the completed risk assessment, available health information and associated
uncertainties, EPA determined risks from the Stationary Combustion Turbines source
category are acceptable with an ample margin of safety to protect public health.

Facility-Wide Risks

•	EPA also assessed facility-wide risks, which include risks from the Stationary Combustion
Turbines source category, as well as other source categories that emit air toxics, like
power plants, compressor stations, landfills and industrial facilities such as chemical
plants.

•	EPA found that the maximum facility-wide cancer risk is 2,000-in-l million. This
estimated risk is caused by ethylene oxide emissions from a variety of industrial
processes that are not part of the Stationary Combustion Turbines source category. In
this assessment, EPA used a 2016-updated risk value for ethylene oxide.

•	EPA is taking a two-pronged approach to address ethylene oxide emissions.

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1.	Reviewing CAA regulations for facilities that emit ethylene oxide.

EPA will review and, as appropriate, revise CAA regulations for facilities that emit
ethylene oxide - starting with the NESHAP for Miscellaneous Organic Chemical
Manufacturing facilities and the NESHAP for Commercial Sterilizers. On December
17, 2019, EPA published proposed amendments to the NEHSAP for Miscellaneous
Organic Chemical Manufacturing facilities, some of which emit ethylene oxide (for
more information, see https://www.epa.gov/stationary-sources-air-
pollution/miscellaneous-organic-chemical-manufacturing-national-emission). And
on December 12, 2019, EPA published an advance notice of proposed rulemaking to
solicit information on various strategies for reducing ethylene oxide emissions from
commercial sterilizers (for more information, see https://www.epa.gov/stationary-
sources-air-pollution/ethylene-oxide-emissions-standards-sterilization-facilities).

2.	Working with state air agencies to gather additional information on ethylene oxide
emissions. This information will help agencies determine whether more immediate
emission reduction steps are necessary in any particular locations.

TECHNOLOGY REVIEW

•	The CAA requires EPA to assess, review and revise air toxics standards, as necessary,
considering developments in practices, processes and control technologies.

•	The technology review of the standards for stationary combustion turbines did not
identify any developments that would further reduce toxic air pollutant emissions
beyond the original NESHAP.

OTHER AMENDMENTS

•	EPA is removing the exemption from meeting the standards during periods of SSM to be
consistent with a 2008 court decision. EPA is finalizing an operational standard for
periods of startup.

•	EPA is requiring electronic submittal of required performance tests and compliance
reports through EPA's Central Data Exchange using the Compliance and Emissions Data
Reporting Interface.

•	EPA is not finalizing the proposed removal of the administrative stay of the standards
for new gas-fired stationary combustion turbines at this time.

BACKGROUND

•	The CAA requires EPA to regulate toxic air pollutants from categories of industrial
facilities in two phases.

•	The first phase is "technology-based," where EPA develops standards for controlling the
emissions of air toxics from sources in an industry group or "source category." These
maximum achievable control technology (MACT) standards are based on emissions

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levels that are already being achieved by the best-controlled and lower-emitting sources
in a source category.

•	Within eight years of setting the MACT standards, the CAA directs EPA to assess the
remaining health risks from each source category to determine whether the MACT
standards protect public health with an ample margin of safety and protect against
adverse environmental effects. This second phase is a "risk-based" approach called
residual risk. Here, EPA must determine whether more health-protective standards are
necessary.

•	Also, every eight years after setting MACT standards, the CAA requires EPA to review
and revise the standards, if necessary, to account for improvements in air pollution
controls and/or prevention.

FOR MORE INFORMATION

•	Interested parties can download a copy of the final rule notice from EPA's website at the
following address: https://www.epa.gov/stationarv-sources-air-pollution/stationary-
combustion-turbines-national-emission-standards.

•	Today's action and other background information are also available either electronically
at https://www.regulations.gov/. EPA's electronic public docket and comment system,
or in hard copy at the EPA Docket Center's Public Reading Room.

o The Public Reading Room is located at the EPA Headquarters Library, WJC West
Building, Room Number 3334,1301 Constitution Ave., 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.

o Visitors are required to show photographic identification, pass through a metal
detector and sign the EPA visitor log. All visitor materials will be processed
through an X-ray machine as well. Visitors will be provided a badge that must be
visible at all times.

o Materials for this action can be accessed using Docket ID No. EPA-HQ-OAR-2017-
0688.

•	For further technical information about the rule, contact Melanie King, EPA's Office of
Air Quality Planning and Standards, at (919) 541-2469 or king.melanie@epa.gov.

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