Proposed Amendments to Air Toxics Standards for Engine Test Cells/Stands
	On April 26, 2019, the U.S. Environmental Protection Agency (EPA) proposed to amend
the 2003 National Emission Standards for Hazardous Air Pollutants (NESHAP) for Engine
Test Cells/Stands.
	EPA is proposing these amendments to enhance the effectiveness of the rule by
improving compliance with federal air emissions standards and increasing efficiency of
data submissions.
	This action includes emission units covered under the NESHAP, namely engine test
cells/stands used for testing uninstalled internal combustion engines with rated power
of 25 horsepower or more.
	On May 27, 2003, EPA issued the Engine Test Cells/Stands air toxics emission standards.
The rule applies to facilities that operate engine test cells/stands at major sources of
hazardous air pollutants.
	Following a residual risk and technology review conducted under the Clean Air Act
(CAA), EPA is proposing to:
o Revise the startup, shutdown and malfunction (SSM) language to be consistent
with recent court decisions; and
o Require affected facilities to submit electronic copies of compliance reports,
including performance test results.
	EPA will accept comment on the proposed amendments for 45 days after publication in
the Federal Register.
	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.
	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.
	The maximum individual cancer risk for inhalation for the source category is estimated
to be 20-in-l million.
	Chronic inhalation cancer risks for actual and allowable emissions were below a Hazard
Index (HI) of 1.

	The CAA also requires EPA to assess, review and revise air toxics standards, as necessary,
taking into account 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 hazardous air pollutant emissions
beyond the original NESHAP.
	The CAA requires EPA to regulate toxic 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 emission levels
that are already being achieved by the best-controlled and lower emitting sources in an
	Within eight years of setting 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
	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.
	EPA will accept comments for 45 days after the proposal is published in the Federal Register.
	Comments, identified by Docket ID No. EPA-HQ-OAR-2018-0753 may be submitted by one of
the following methods:
o Go to https://www.regulations.gov and follow the online instructions for submitting
o Send comments by email to a-and-r-docket@epa.gov. Attention Docket ID No. EPA-
o Fax your comments to: 202-566-9744, Attention Docket ID. No. EPA-HQ-OAR-2018-
o Mail your comments to: EPA Docket Center, Environmental Protection Agency, Mail
Code: 28221T, 1200 Pennsylvania Ave., NW, Washington, DC 20460, Attention
Docket ID. No. EPA-HQ-OAR-2018-0753.
o Deliver comments in person to: EPA Docket Center (EPA/DC), EPA WJC West Building,

1301 Constitution Ave., NW, Room 3334, Washington, DC. Attention Docket ID. No.
EPA-HQ-OAR-2018-0753. Note: In-person deliveries (including courier deliveries) are
only accepted during the Docket's normal hours of operation. Special arrangements
should be made for deliveries of boxed information.
	Interested parties can download a copy of the proposed rule notice from EPA's website
at the following address: https://www.epa.gov/stationary-sources-air-pollution/engine-
	Today's proposed 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 EPA Headquarters library, room number
3334 in the EPA WJC West Building, 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 proposed action can be accessed using Docket ID No. EPA-HQ-
	For further technical information about the proposed rule, contact Jim Eddinger at EPA's
Office of Air Quality Planning and Standards, Sector Policies and Programs Division, at
(919) 541-5426 or at eddinger.jim@epa.gov.