FACT SHEET

Final Amendments to Air Toxics Standards for Engine Test Cells/Stands

ACTION

•	On March 11, 2020, the U.S. Environmental Protection Agency (EPA) finalized
amendments to the 2003 National Emission Standards for Hazardous Air Pollutants
(NESHAP) for Engine Test Cells/Stands located at major sources of air toxics.

•	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
standards. This is known as a residual risk assessment.

•	The maximum individual cancer risk (MIR) for inhalation based on allowable emissions
for the source category is estimated to be 70-in-l million.

•	An MIR of 70-in-l million implies that up to 70 people out of 1 million equally exposed
people could contract cancer if exposed continuously (24 hours per day) to the specific
concentration over 70 years (an assumed lifetime). This would be in addition to cancer
cases that would normally occur in 1 million unexposed people.

•	Chronic inhalation cancer risks for actual and allowable emissions were below a hazard index
of 1. A hazard index of 1 or lower means air toxics are unlikely to cause adverse noncancer
health effects over a lifetime of exposure.

•	Based on the completed risk assessment, available health information and associated
uncertainties, EPA determined risks from the engine test cells/stands sector to be
acceptable and provide an ample margin of safety to protect public health.

TECHNOLOGY REVIEW

•	The CAA also 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 facilities with engine test cells/stands did not
identify any developments that would further reduce toxic air pollutant emissions
beyond the original NESHAP.

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OTHER AMENDMENTS

•	EPA is removing the exemption from meeting the standards during periods of SSM to be
consistent with a 2008 court decision and clarifying that the standards are applicable at
all times.

•	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.

BACKGROUND

•	The CAA requires EPA to regulate hazardous air pollutants, also known as air toxics, 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
levels that are already being achieved by the best-controlled and lower emitting sources
in an industry.

•	The CAA directs EPA to, within eight years of setting the MACT standards, 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 prevention practices and technologies.

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/stationary-sources-air-pollution/engine-test-
cellsstands-national-emission-standards-hazardous-air.

•	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 hardcopy 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.

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o Materials for this action can be accessed using Docket ID No. EPA-HQ-OAR-2018-
0753.

• For further technical information about the rule, contact Christopher Werner, EPA's
Office of Air Quality Planning and Standards, at (919) 541-5133 or
werner.christopher@epa.gov.

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