[Federal Register Volume 88, Number 15 (Tuesday, January 24, 2023)]
[Rules and Regulations]
[Pages 4296-4718]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-27957]
[[Page 4295]]
Vol. 88
Tuesday,
No. 15
January 24, 2023
Part II
Environmental Protection Agency
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40 CFR Parts 2, 59, 60, et al.
Control of Air Pollution From New Motor Vehicles: Heavy-Duty Engine and
Vehicle Standards; Final Rule
Federal Register / Vol. 88 , No. 15 / Tuesday, January 24, 2023 /
Rules and Regulations
[[Page 4296]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 2, 59, 60, 80, 85, 86, 600, 1027, 1030, 1031, 1033,
1036, 1037, 1039, 1042, 1043, 1045, 1048, 1051, 1054, 1060, 1065,
1066, 1068, and 1090
[EPA-HQ-OAR-2019-0055; FRL-7165-02-OAR]
RIN 2060-AU41
Control of Air Pollution From New Motor Vehicles: Heavy-Duty
Engine and Vehicle Standards
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The Environmental Protection Agency (EPA) is finalizing a
program to further reduce air pollution, including ozone and
particulate matter (PM), from heavy-duty engines and vehicles across
the United States. The final program includes new emission standards
that are significantly more stringent and that cover a wider range of
heavy-duty engine operating conditions compared to today's standards;
further, the final program requires these more stringent emissions
standards to be met for a longer period of when these engines operate
on the road. Heavy-duty vehicles and engines are important contributors
to concentrations of ozone and particulate matter and their resulting
threat to public health, which includes premature death, respiratory
illness (including childhood asthma), cardiovascular problems, and
other adverse health impacts. The final rulemaking promulgates new
numeric standards and changes key provisions of the existing heavy-duty
emission control program, including the test procedures, regulatory
useful life, emission-related warranty, and other requirements.
Together, the provisions in the final rule will further reduce the air
quality impacts of heavy-duty engines across a range of operating
conditions and over a longer period of the operational life of heavy-
duty engines. The requirements in the final rule will lower emissions
of NOX and other air pollutants (PM, hydrocarbons (HC),
carbon monoxide (CO), and air toxics) beginning no later than model
year 2027. We are also finalizing limited amendments to the regulations
that implement our air pollutant emission standards for other sectors
(e.g., light-duty vehicles, marine diesel engines, locomotives, and
various other types of nonroad engines, vehicles, and equipment).
DATES: This final rule is effective on March 27, 2023. The
incorporation by reference of certain material listed in this rule is
approved by the Director of the Federal Register as of March 27, 2023.
ADDRESSES: Docket: EPA has established a docket for this action under
Docket ID No. EPA-HQ-OAR-2019-0055. Publicly available docket materials
are available either electronically at www.regulations.gov or in hard
copy at Air and Radiation Docket and Information Center, EPA Docket
Center, EPA/DC, EPA WJC West Building, 1301 Constitution Ave., NW, Room
3334, Washington, DC. Out of an abundance of caution for members of the
public and our staff, the EPA Docket Center and Reading Room are open
to the public by appointment only to reduce the risk of transmitting
COVID-19. Our Docket Center staff also continues to provide remote
customer service via email, phone, and webform. Hand deliveries and
couriers may be received by scheduled appointment only. For further
information on EPA Docket Center services and the current status,
please visit us online at www.epa.gov/dockets.
FOR FURTHER INFORMATION CONTACT: Brian Nelson, Assessment and Standards
Division, Office of Transportation and Air Quality, Environmental
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105;
telephone number: (734) 214-4278; email address: [email protected].
SUPPLEMENTARY INFORMATION:
Does this action apply to me?
This action relates to companies that manufacture, sell, or import
into the United States new heavy-duty highway engines. Additional
amendments apply for gasoline refueling facilities and for
manufacturers of all sizes and types of motor vehicles, stationary
engines, aircraft and aircraft engines, and various types of nonroad
engines, vehicles, and equipment. Regulated categories and entities
include the following:
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NAICS codes \a\ NAICS title
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326199.............................. All Other Plastics Product
Manufacturing.
332431.............................. Metal Can Manufacturing.
333618.............................. Manufacturers of new marine diesel
engines.
335312.............................. Motor and Generator Manufacturing.
336111.............................. Automobile Manufacturing.
336112.............................. Light Truck and Utility Vehicle
Manufacturing.
336120.............................. Heavy Duty Truck Manufacturing.
336211.............................. Motor Vehicle Body Manufacturing.
336213.............................. Motor Home Manufacturing.
336411.............................. Manufacturers of new aircraft.
336412.............................. Manufacturers of new aircraft
engines.
333618.............................. Other Engine Equipment
Manufacturing.
336999.............................. All Other Transportation Equipment
Manufacturing.
423110.............................. Automotive and Other Motor Vehicle
Merchant Wholesalers.
447110.............................. Gasoline Stations with Convenience
Stores.
447190.............................. Other Gasoline Stations.
454310.............................. Fuel dealers.
811111.............................. General Automotive Repair.
811112.............................. Automotive Exhaust System Repair.
811198.............................. All Other Automotive Repair and
Maintenance.
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\a\ NAICS Association. NAICS & SIC Identification Tools. Available
online: https://www.naics.com/search.
This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. This table lists the types of entities that EPA is now aware
could potentially be regulated by this action. Other types of entities
not listed in the table could also be regulated. To determine whether
your entity is regulated by this action, you should carefully examine
the applicability criteria found in Sections XI and XII of this
preamble. If you have questions regarding the applicability of this
action to a particular entity, consult the person listed in the FOR
FURTHER INFORMATION CONTACT section.
Public participation: Docket: All documents in the docket are
listed on the www.regulations.gov website. Although listed in the
index, some information is not publicly available, e.g., CBI or other
information whose disclosure is restricted by statute. Certain other
material, such as copyrighted material, is not placed on the internet
and will be publicly available only in hard copy form through the EPA
Docket Center at the location listed in the ADDRESSES section of this
document.
What action is the agency taking?
The Environmental Protection Agency (EPA) is adopting a rule to
reduce air pollution from highway heavy-duty vehicles and engines. The
final rulemaking will promulgate new numeric standards and change key
provisions of the existing heavy-duty emission control program,
including the
[[Page 4297]]
test procedures, regulatory useful life, emission-related warranty, and
other requirements. Together, the provisions in the final rule will
further reduce the air quality impacts of heavy-duty engines across a
range of operating conditions and over a longer period of the
operational life of heavy-duty engines. Heavy-duty vehicles and engines
are important contributors to concentrations of ozone and particulate
matter and their resulting threat to public health, which includes
premature death, respiratory illness (including childhood asthma),
cardiovascular problems, and other adverse health impacts. This final
rule will reduce emissions of nitrogen oxides and other pollutants.
What is the agency's authority for taking this action?
Clean Air Act section 202(a)(1) requires that EPA set emission
standards for air pollutants from new motor vehicles or new motor
vehicle engines that the Administrator has found cause or contribute to
air pollution that may endanger public health or welfare. See Sections
I.D and XIII of this preamble for more information on the agency's
authority for this action.
What are the incremental costs and benefits of this action?
Our analysis of the final standards shows that annual total costs
for the final program relative to the baseline (or no action scenario)
range from $3.9 billion in 2027 to $4.7 billion in 2045 (2017 dollars,
undiscounted, see Table V-16). The present value of program costs for
the final rule, and additional details are presented in Section V.
Section VIII presents our analysis of the human health benefits
associated with the final standards. We estimate that in 2045, the
final rule will result in total annual monetized ozone- and
PM2.5-related benefits of $12 and $33 billion at a 3 percent
discount rate, and $10 and $30 billion at a 7 percent discount rate
(2017 dollars, discount rate applied to account for mortality cessation
lag, see Table VIII-3).\1\ These benefits only reflect those associated
with reductions in NOX emissions (a precursor to both ozone
and secondarily-formed PM2.5) and directly-emitted
PM2.5 from highway heavy-duty engines. The agency was unable
to quantify or monetize all the benefits of the final program,
therefore the monetized benefit values are underestimates. There are
additional human health and environmental benefits associated with
reductions in exposure to ambient concentrations of PM2.5,
ozone, and NO2 that data, resource, or methodological
limitations have prevented EPA from quantifying. There will also be
benefits associated with reductions in air toxic pollutant emissions
that result from the final program, but we did not attempt to monetize
those impacts because of methodological limitations. More detailed
information about the benefits analysis conducted for the final rule,
including the present value of program benefits, is included in Section
VIII and RIA Chapter 8. We compare total monetized health benefits to
total costs associated with the final rule in Section IX. Our results
show that annual benefits of the final rule will be larger than the
annual costs in 2045, with annual net benefits of $6.9 and $29 billion
assuming a 3 percent discount rate, and net benefits of $5.8 and $25
billion assuming a 7 percent discount rate.\2\ The benefits of the
final rule also outweigh the costs when expressed in present value
terms and as equalized annual values (see Section IX for these values).
See Section VIII for more details on the net benefit estimates
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\1\ 2045 is a snapshot year chosen to approximate the annual
health benefits that occur when the final program will be fully
implemented and when most of the regulated fleet will have turned
over.
\2\ The range of benefits and net benefits reflects a
combination of assumed PM2.5 and ozone mortality risk
estimates and selected discount rate.
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Did EPA conduct a peer review before issuing this action?
This regulatory action was supported by influential scientific
information. EPA therefore conducted peer review in accordance with
OMB's Final Information Quality Bulletin for Peer Review. Specifically,
we conducted peer review on five analyses: (1) Analysis of Heavy-Duty
Vehicle Sales Impacts Due to New Regulation (Sales Impacts), (2)
Exhaust Emission Rates for Heavy-Duty Onroad Vehicles in MOVES_CTI NPRM
(Emission Rates), (3) Population and Activity of Onroad Vehicles in
MOVES_CTI NPRM (Population and Activity), (4) Cost teardowns of Heavy-
Duty Valvetrain (Valvetrain costs), and (5) Cost teardown of Emission
Aftertreatment Systems (Aftertreatment Costs). All peer review was in
the form of letter reviews conducted by a contractor. The peer review
reports for each analysis are in the docket for this action and at
EPA's Science Inventory (https://cfpub.epa.gov/si/).
Table of Contents
I. Executive Summary
A. Introduction
B. Overview of the Final Regulatory Action
C. Impacts of the Standards
D. EPA Statutory Authority for This Action
II. Need for Additional Emissions Control
A. Background on Pollutants Impacted by This Proposal
B. Health Effects Associated With Exposure to Pollutants
Impacted by This Rule
C. Environmental Effects Associated With Exposure to Pollutants
Impacted by This Rule
D. Environmental Justice
III. Test Procedures and Standards
A. Overview
B. Summary of Compression-Ignition Exhaust Emission Standards
and Duty Cycle Test Procedures
C. Summary of Compression-Ignition Off-Cycle Standards and Off-
Cycle Test Procedures
D. Summary of Spark-Ignition HDE Exhaust Emission Standards and
Test Procedures
E. Summary of Spark-Ignition HDV Refueling Emission Standards
and Test Procedures
IV. Compliance Provisions and Flexibilities
A. Regulatory Useful Life
B. Ensuring Long-Term In-Use Emissions Performance
C. Onboard Diagnostics
D. Inducements
E. Fuel Quality
F. Durability Testing
G. Averaging, Banking, and Trading
V. Program Costs
A. Technology Package Costs
B. Operating Costs
C. Program Costs
VI. Estimated Emissions Reductions From the Final Program
A. Emission Inventory Methodology
B. Estimated Emission Reductions From the Final Program
C. Estimated Emission Reductions by Engine Operations and
Processes
VII. Air Quality Impacts of the Final Rule
A. Ozone
B. Particulate Matter
C. Nitrogen Dioxide
D. Carbon Monoxide
E. Air Toxics
F. Visibility
G. Nitrogen Deposition
H. Demographic Analysis of Air Quality
VIII. Benefits of the Heavy-Duty Engine and Vehicle Standards
IX. Comparison of Benefits and Costs
A. Methods
B. Results
X. Economic Impact Analysis
A. Impact on Vehicle Sales, Mode Shift, and Fleet Turnover
B. Employment Impacts
XI. Other Amendments
A. General Compliance Provisions (40 CFR Part 1068) and Other
Cross-Sector Issues
B. Heavy-Duty Highway Engine and Vehicle Emission Standards (40
CFR Parts 1036 and 1037)
C. Fuel Dispensing Rates for Heavy-Duty Vehicles (40 CFR Parts
80 and 1090)
D. Refueling Interface for Motor Vehicles (40 CFR Parts 80 and
1090)
E. Light-Duty Motor Vehicles (40 CFR Parts 85, 86, and 600)
F. Large Nonroad Spark-Ignition Engines (40 CFR Part 1048)
[[Page 4298]]
G. Small Nonroad Spark-Ignition Engines (40 CFR Part 1054)
H. Recreational Vehicles and Nonroad Evaporative Emissions (40
CFR Parts 1051 and 1060)
I. Marine Diesel Engines (40 CFR Parts 1042 and 1043)
J. Locomotives (40 CFR Part 1033)
K. Stationary Compression-Ignition Engines (40 CFR Part 60,
subpart IIII)
L. Nonroad Compression-Ignition Engines (40 CFR Part 1039)
XII. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Paperwork Reduction Act (PRA)
C. Regulatory Flexibility Act (RFA)
D. Unfunded Mandates Reform Act (UMRA)
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
K. Congressional Review Act
L. Judicial Review
XIII. Statutory Provisions and Legal Authority
I. Executive Summary
A. Introduction
1. Summary of the Final Criteria Pollutant Program
In this action, the EPA is finalizing a program to further reduce
air pollution, including pollutants that create ozone and particulate
matter (PM), from heavy-duty engines and vehicles across the United
States. The final program includes new, more stringent emissions
standards that cover a wider range of heavy-duty engine operating
conditions compared to today's standards, and it requires these more
stringent emissions standards to be met for a longer period of time of
when these engines operate on the road.
This final rule is part of a comprehensive strategy, the ``Clean
Trucks Plan,'' which lays out a series of clean air and climate
regulations that the agency is developing to reduce pollution from
large commercial heavy-duty trucks and buses, as well as to advance the
transition to a zero-emissions transportation future. Consistent with
President Biden's Executive Order (E.O.) 14037, this final rule is the
first step in the Clean Trucks Plan.\3\ We expect the next two steps of
the Clean Trucks Plan will take into consideration recent Congressional
action, including the recent Inflation Reduction Act of 2022, that we
anticipate will spur significant change in the heavy-duty sector.\4\ We
are not taking final action at this time on the proposed targeted
updates to the existing Heavy-Duty Greenhouse Gas Emissions Phase 2
program (HD GHG Phase 2); rather, we intend to consider potential
changes to certain HD GHG Phase 2 standards as part of a subsequent
rulemaking.
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\3\ President Joseph Biden. Executive Order on Strengthening
American Leadership in Clean Cars and Trucks. 86 FR 43583, August
10, 2021.
\4\ For example, both the 2021 Infrastructure Investment and
Jobs Act (commonly referred to as the ``Bipartisan Infrastructure
Law'' or BIL) and the Inflation Reduction Act of 2022 (``Inflation
Reduction Act'' or IRA) include many incentives for the development,
production, and sale of zero emissions vehicles (ZEVs) and charging
infrastructure. Infrastructure Investment and Jobs Act, Public Law
117-58, 135 Stat. 429 (2021) (``Bipartisan Infrastructure Law'' or
``BIL''), available at https://www.congress.gov/117/plaws/publ58/PLAW-117publ58.pdf; Inflation Reduction Act of 2022, Public Law 117-
169, 136 Stat. 1818 (2022) (``Inflation Reduction Act'' or ``IRA''),
available at https://www.congress.gov/117/bills/hr5376/BILLS-117hr5376enr.pdf.
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Across the United States, heavy-duty engines emit oxides of
nitrogen (NOX) and other pollutants that are significant
contributors to concentrations of ozone and PM2.5 and their
resulting adverse health effects, which include death, respiratory
illness (including childhood asthma), and cardiovascular
problems.5 6 7 Without this final rule, heavy-duty engines
would continue to be one of the largest contributors to mobile source
NOX emissions nationwide in the future, representing 32
percent of the mobile source NOX emissions in calendar year
2045.\8\ Furthermore, we estimate that without this final rule, heavy-
duty engines would represent 90 percent of the onroad NOX
inventory in calendar year 2045.\9\ Reducing NOX emissions
is a critical part of many areas' strategies to attain and maintain the
National Ambient Air Quality Standards (NAAQS) for ozone and PM; many
state and local agencies anticipate challenges in attaining the NAAQS,
maintaining the NAAQS in the future, and/or preventing
nonattainment.\10\ Some nonattainment areas have already been ``bumped
up'' to higher classifications because of challenges in attaining the
NAAQS.\11\
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\5\ Oxides of nitrogen (NOX) refers to nitric oxide
(NO) and nitrogen dioxide (NOX).
\6\ Zawacki et al, 2018. Mobile source contributions to ambient
ozone and particulate matter in 2025. Atmospheric Environment, Vol
188, pg 129-141. Available online: https://doi.org/10.1016/j.atmosenv.2018.04.057.
\7\ Davidson et al, 2020. The recent and future health burden of
the U.S. mobile sector apportioned by source. Environmental Research
Letters. Available online: https://doi.org/10.1088/1748-9326/ab83a8.
\8\ Sectors other than onroad and nonroad were projected from
2016v1 Emissions Modeling Platform. https://www.epa.gov/air-emissions-modeling/2016v1-platform.
\9\ U.S. EPA (2020) Motor Vehicle Emission Simulator: MOVES3.
https://www.epa.gov/moves.
\10\ See Section II for additional detail.
\11\ For example, in September 2019 several 2008 ozone
nonattainment areas were reclassified from moderate to serious,
including Dallas, Chicago, Connecticut, New York/New Jersey and
Houston, and in January 2020, Denver. Also, on September 15, 2022,
EPA finalized reclassification of 5 areas in nonattainment of the
2008 ozone NAAQS from serious to severe and 22 areas in
nonattainment of the 2015 ozone NAAQS from marginal to moderate. The
2008 NAAQS for ozone is an 8-hour standard with a level of 0.075
ppm, which the 2015 ozone NAAQS lowered to 0.070 ppm.
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In addition, emissions from heavy-duty engines can result in higher
pollutant levels for people living near truck freight routes. Based on
a study EPA conducted of people living near truck routes, an estimated
72 million people live within 200 meters of a truck freight route.\12\
Relative to the rest of the population, people of color and those with
lower incomes are more likely to live near truck routes.\13\ This
population includes children; childcare facilities and schools can also
be in close proximity to freight routes.\14\
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\12\ See discussion in Section II.B.7.
\13\ See Section VII.H for additional discussion on our analysis
of environmental justice impacts of this final rule.
\14\ Kingsley, S., Eliot, M., Carlson, L. et al. Proximity of
U.S. schools to major roadways: a nationwide assessment. J Expo Sci
Environ Epidemiol 24, 253-259 (2014). https://doi.org/10.1038/jes.2014.5.
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The final rulemaking will promulgate new numeric standards and
change key provisions of the existing heavy-duty emission control
program, including the test procedures, regulatory useful life,
emission-related warranty, and other requirements. Together, the
provisions in the final rule will further reduce the air quality
impacts of heavy-duty engines across a range of operating conditions
and over a longer portion of the operational life of heavy-duty
engines.\15\ The requirements in the final
[[Page 4299]]
rule will lower emissions of NOX and other air pollutants
(PM, hydrocarbons (HC), carbon monoxide (CO), and air toxics) beginning
no later than model year (MY) 2027. The emission reductions from the
final rule will increase over time as more new, cleaner vehicles enter
the fleet.
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\15\ Note that the terms useful life and operational life are
different, though they are related. As required by Clean Air Act
(CAA) section 202(a), the useful life period is when manufacturers
are required to meet the emissions standards in the final rule;
whereas, operational life is the term we use to describe the
duration over which an engine is operating on roadways. We are
finalizing useful life periods that cover a greater portion of the
operational life. We consider operational life to be the average
mileage at rebuild for compression-ignition engines and the average
mileage at replacement for spark-ignition engines (see preamble
Section IV.A for details).
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We estimate that the final rule will reduce NOX
emissions from heavy-duty vehicles in 2040 by more than 40 percent; by
2045, a year by which most of the regulated fleet will have turned
over, heavy-duty NOX emissions will be almost 50 percent
lower than they would have been without this action. These emission
reductions will result in widespread decreases in ambient
concentrations of pollutants such as ozone and PM2.5. We
estimate that in 2045, the final rule will result in total annual
monetized ozone- and PM2.5-related benefits of $12 and $33
billion at a 3 percent discount rate, and $10 and $30 billion at a 7
percent discount rate. These widespread air quality improvements will
play an important role in addressing concerns raised by state, local,
and Tribal governments, as well as communities, about the contributions
of heavy-duty engines to air quality challenges they face such as
meeting their obligations to attain or continue to meet NAAQS, and to
reduce other human health and environmental impacts of air pollution.
This rule's emission reductions will reduce air pollution in close
proximity to major roadways, where concentrations of many air
pollutants are elevated and where people of color and people with low
income are disproportionately exposed.
In EPA's judgment, our analyses in this final rule show that the
final standards will result in the greatest degree of emission
reduction achievable starting in model year 2027, giving appropriate
consideration to costs and other factors, which is consistent with
EPA's statutory authority under Clean Air Act (CAA) section
202(a)(3)(A).\16\
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\16\ CAA section 202(a)(3)(A) requires standards for emissions
of NOX, PM, HC, and CO emissions from heavy-duty vehicles
and engines to ``reflect the greatest degree of emission reduction
achievable through the application of technology which the
Administrator determines will be available for the model year to
which such standards apply, giving appropriate consideration to
cost, energy, and safety factors associated with the application of
such technology.'' Throughout this notice we use terms like
``maximum feasible emissions reductions'' to refer to this statutory
requirement to set standards that ``reflect the greatest degree of
emission reduction achievable . . .'.
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CAA section 202(a)(1) requires the EPA to ``by regulation prescribe
(and from time to time revise) . . . standards applicable to the
emission of any air pollutant from any class or classes of new motor
vehicles or new motor vehicle engines . . . , which in his judgment
cause, or contribute to, air pollution which may reasonably be
anticipated to endanger public health or welfare.'' CAA section
202(a)(3)(C) requires that NOX, PM, HC, and CO (hereafter
referred to as ``criteria pollutants'') standards for certain heavy-
duty vehicles and engines apply for no less than 3 model years and
apply no earlier than 4 years after promulgation.\17\
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\17\ See Sections I.D and XIII for additional discussion on
EPA's statutory authority for this action, including our authority
under CAA sections 202(d) and 207.
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Although heavy-duty engines have become much cleaner over the last
decade, catalysts and other technologies have evolved such that harmful
air pollutants can be reduced even further. The final standards are
based on technology improvements that have become available over the 20
years since the last major rule was promulgated to address emissions of
criteria pollutants and toxic pollutants from heavy-duty engines, as
well as projections of continued technology improvements that build on
these existing technologies. The criteria pollutant provisions we are
adopting in this final rule apply for all heavy-duty engine (HDE)
classes: Spark-ignition (SI) HDE, as well as compression-ignition (CI)
Light HDE, CI Medium HDE, and CI Heavy HDE.\18\
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\18\ This final rule includes new criteria pollutant standards
for engine-certified Class 2b through 8 heavy-duty engines and
vehicles. Class 2b and 3 vehicles with a Gross Vehicle Weight Rating
(GVWR) between 8,500 and 14,000 pounds are primarily commercial
pickup trucks and vans and are sometimes referred to as ``medium-
duty vehicles.'' The majority of Class 2b and 3 vehicles are
chassis-certified vehicles, and EPA intends to include them in a
future combined light-duty and medium-duty rulemaking action,
consistent with E.O, 14037, Section 2a. SI HDE are typically fueled
by gasoline, whereas CI HDE are typically fueled by diesel; note
that the Heavy HDE class, which is largely CI engines, does include
certain SI engines that are generally natural gas-fueled engines
intended for use in Class 8 vehicles. See 40 CFR 1036.140 for
additional description of the primary intended service classes for
heavy-duty engines. Heavy-duty engines and vehicles are also used in
nonroad applications, such as construction equipment; nonroad heavy-
duty engines and vehicles are not the focus of this final rule. As
outlined in I.B of this Executive Summary and detailed in Section
XI, this final rule also includes limited amendments to regulations
that implement our air pollutant emission standards for other
industry sectors, including light-duty vehicles, light-duty trucks,
marine diesel engines, locomotives, and various types of nonroad
engines, vehicles, and equipment. See 40 CFR 1036.140 for a
description of the primary intended service classes for heavy-duty
engines.
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As described in Section III, the final standards will reduce
emissions during a broader range of operating conditions compared to
the current standards, such that nearly all in-use operation will be
covered. Available data indicate that emission levels demonstrated for
certification are not currently achieved under the broad range of real-
world operating conditions.19 20 21 22 In fact, less than
ten percent of the data collected during a typical test while the
vehicle is operated on the road is subject to EPA's current on-the-road
emission standards.\23\ These testing data further show that
NOX emissions from heavy-duty CI engines are high during
many periods of vehicle operation that are not subject to current on-
the-road emission standards. For example, ``low-load'' engine
conditions occur when a vehicle operates in stop-and-go traffic or is
idling; these low-load conditions can result in exhaust temperature
decreases that then lead to the diesel engine's selective catalytic
reduction (SCR)-based emission control system becoming less effective
or ceasing to function. Test data collected as part of EPA's
manufacturer-run in-use testing program indicate that this low-load
operation could account for more than half of the NOX
emissions from a vehicle during a typical workday.\24\ Similarly,
heavy-duty SI engines also operate in conditions where their catalyst
technology becomes less effective, resulting in higher levels of air
pollutants; however, unlike CI engines, it is sustained medium-to-high
load operation where emission levels are less certain. To address these
concerns, as part of our comprehensive approach, the final standards
include both revisions to our existing test procedures and new test
procedures to reduce emissions
[[Page 4300]]
from heavy-duty engines under a broader range of operating conditions,
including low-load conditions.
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\19\ Hamady, Fakhri, Duncan, Alan. ``A Comprehensive Study of
Manufacturers In-Use Testing Data Collected from Heavy-Duty Diesel
Engines Using Portable Emissions Measurement System (PEMS).'' 29th
CRC Real World Emissions Workshop, March 10-13, 2019.
\20\ Sandhu, Gurdas, et al. ``Identifying Areas of High
NOX Operation in Heavy-Duty Vehicles''. 28th CRC Real-
World Emissions Workshop, March 18-21, 2018.
\21\ Sandhu, Gurdas, et al. ``In-Use Emission Rates for MY 2010+
Heavy-Duty Diesel Vehicles''. 27th CRC Real-World Emissions
Workshop, March 26-29, 2017.
\22\ As noted in Section I.B and discussed in Section III,
testing engines and vehicles while they are operating without a
defined duty cycle is referred to as ``off-cycle'' testing; as
detailed in Section III, we are finalizing new off-cycle test
procedures and standards as part of this rulemaking.
\23\ Heavy-duty CI engines are currently subject to off-cycle
standards that are not limited to specific test cycles; throughout
this notice we use the terms ``on-the-road'', ``over the road'', or
``real world'' interchangeably to refer to off-cycle standards.
\24\ Sandhu, Gurdas, et al. ``Identifying Areas of High
NOX Operation in Heavy-Duty Vehicles''. 28th CRC Real-
World Emissions Workshop, March 18-21, 2018.
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Data also show that tampering and mal-maintenance of the engine's
emission control system after the useful life period is projected to
result in NOX emissions that would represent a substantial
part of the HD emissions inventory in 2045.\25\ To address this
problem, as part of our comprehensive approach, the final rule includes
longer regulatory useful life and emission-related warranty
requirements to ensure the final emissions standards will be met
through more of the operational life of heavy-duty
vehicles.26 27 Further, the final rule includes requirements
for manufacturers to better ensure that operators keep in-use engines
and emission control systems working properly in the real world. We
expect these final provisions to improve maintenance and serviceability
will reduce incentives to tamper with the emission control systems on
MY 2027 and later engines, which would avoid large increases in
emissions that would impact the reductions projected from the final
rule. For example, we estimate NOX emissions will increase
more than 3000 percent due to malfunction of the NOX
emissions aftertreatment on a MY 2027 and later heavy heavy-duty
vehicle. To address this, the final rule requires manufacturers to meet
emission standards with less frequent scheduled maintenance for
emission-related parts and systems, and to provide more information on
how to diagnose and repair emission control systems. In addition, the
final rule requires manufacturers to demonstrate that they design their
engines to limit access to electronic controls to prevent operators
from reprogramming the engine to bypass or disable emission controls.
The final rule also specifies a balanced approach for manufacturers to
design their engines with features to ensure that operators perform
ongoing maintenance to keep SCR emission control systems working
properly, without creating a level of burden and corresponding
frustration for operators that could increase the risk of operators
completely disabling emission control systems. These provisions
combined with the longer useful life and warranty periods will provide
a comprehensive approach to ensure that the new, much more stringent
emissions standards are met during in use operations.
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\25\ See Section VI for more information on projected inventory
contributions from each operating mode or process, as well as
discussion on the emissions impacts of tampering and mal-
maintenance.
\26\ Emission standards set under CAA section 202(a) apply to
vehicles and engines ``for their useful life.'' CAA section 202(d)
directs EPA to prescribe regulations under which the useful life of
vehicles and engines shall be determined, and for heavy-duty
vehicles and engines establishes minimum values of 10 years or
100,000 miles, whichever occurs first, unless EPA determines that
greater values are appropriate. CAA section 207(a) further requires
manufacturers to provide emission-related warranty, and EPA set the
current emission-related warranty periods for heavy-duty engines in
1983 (48 FR 52170, November 16, 1983). See Section I.D for more
discussion on the statutory authority for the final rule.
\27\ See Section IV for more discussion on the final useful life
and warranty requirements.
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The final standards and requirements are based on further
consideration of the data included in the proposed rule, as well as
additional supporting data from our own test programs, and
consideration of the extensive public input EPA received in response to
the proposed rule. The proposal was posted on the EPA website on March
7, 2022, and published in the Federal Register on March 28, 2022 (87 FR
17414, March 28, 2022). EPA held three virtual public hearings in April
2022. We received more than 260,000 public comments.\28\ A broad range
of stakeholders provided comments, including state and local
governments, heavy-duty engine manufacturers, emissions control
suppliers and others in the heavy-duty industry, environmental
organizations, environmental justice organizations, state, local, and
Tribal organizations, consumer groups, labor groups, private citizens,
and others. Some of the issues raised in comments included the need for
new, more stringent NOX standards, particularly in
communities already overburdened by pollution; the feasibility and
costs of more stringent NOX standards combined with much
longer useful life periods; the longer emissions-related warranty
periods; a single- vs. two-step program; and various details on the
flexibilities and other program design features of the proposed
program. We briefly discuss several of these key issues in Section I.B,
with more detail in later sections in this preamble and in the Response
to Comments document that is available in the public docket for this
rule.\29\
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\28\ Of these comments, 1,860 were unique letters, many of which
provided data and other detailed information for EPA to consider;
the remaining comments were mass mailers sponsored by 30 different
organizations, nearly all of which urged EPA to take action to
reduce emissions from trucks or to adopt more stringent limits.
\29\ U.S. EPA, ``Control of Air Pollution from New Motor
Vehicles: Heavy-Duty Engine and Vehicle Standards--Response to
Comments'', Docket EPA-HQ-OAR-2019-0055.
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This Section I provides an overview of the final program, the
impacts of the final program, and how the final program is consistent
with EPA's statutory requirements. The need for additional emissions
control from heavy-duty engines is described in Section II. We describe
the final standards and compliance flexibilities in detail in Sections
III and IV. We discuss our analyses of estimated emission reductions,
air quality improvements, costs, and monetized benefits of the final
program in Sections V through X. Section XI describes limited
amendments to the regulations that implement our air pollutant emission
standards for other sectors (e.g., light-duty vehicles, marine diesel
engines, locomotives, and various types of nonroad engines, vehicles,
and equipment).
2. EPA Will Address HD GHG Emissions in a Subsequent Rulemaking
Although we proposed targeted revisions to the MY2027 GHG Phase 2
standards as part of the same proposal in which we laid out more
stringent NOX standards, in this final rule we are not
taking final action on updates to the GHG standards. Instead, we intend
to consider potential changes to certain HD GHG Phase 2 standards as
part of a subsequent rulemaking.
B. Overview of the Final Regulatory Action
We are finalizing a program that will begin in MY 2027, which is
the earliest year that these new criteria pollutant standards can begin
to apply under CAA section 202(a)(3)(C).\30\ The final NOX
standards are a single-step program that reflect the greatest degree of
emission reduction achievable starting in MY2027, giving appropriate
consideration to costs and other factors. The final rule establishes
not only new, much more stringent NOX standards compared to
today's standards, but also requires lower NOX emissions
over a much wider range of testing conditions both in the laboratory
and when engines are operating on the road. Further, the final
standards include longer useful life periods, as well as significant
increases in the emissions-related warranty periods. The longer useful
life and emissions warranty periods are particularly important for
ensuring continued emissions control when the engines are operating on
the road. These final standards will result in significant reductions
in emissions of NOX, PM2.5, and other air
pollutants across the country, which we project will meaningfully
decrease ozone
[[Page 4301]]
concentrations across the country. We expect the largest improvements
in both ozone and PM2.5 to occur in areas with the worst
baseline air quality. In a supplemental demographic analysis, we also
found that larger numbers of people of color are projected to reside in
these areas with the worst baseline air quality.
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\30\ Section 202(a)(3)(C) requires that standards under
202(a)(3)(A), such as the standards in this final rule, apply no
earlier than 4 years after promulgation, and apply for no less than
3 model years. See Section I.D for additional discussion on the
statutory authority for this action.
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The final standards and requirements are based on further
consideration of the data included in the proposed rule, as well as
additional supporting data from our own test programs, and
consideration of the extensive public input EPA received in response to
the proposed rule. As required by CAA section 202(a)(3), the final new
numeric NOX standards will result in the greatest degree of
emission reduction achievable for a national program starting in MY
2027 through the application of technology that the Administrator has
determined will be available starting in MY 2027, after giving
appropriate consideration to cost, energy, and safety factors
associated with the application of such technology. The EPA proposal
included two options for the NOX program. Proposed Option 1
was the more stringent option, and it included new standards and other
program elements starting in MY 2027, which were further strengthened
in MY 2031. Proposed Option 2 was the less stringent option, with new
standards and requirements implemented fully in MY 2027. The final
numeric NOX standards and testing requirements are largely
consistent with the proposed Option 1 in MY 2027. The final numeric
standards and regulatory useful life values will reduce NOX
emissions not only when trucks are new, but throughout a longer period
of their operational life under real-world conditions. For the smaller
engine service-class categories, we are finalizing the longest
regulatory useful life and emissions warranty periods proposed, and for
the largest engines we are finalizing requirements for useful life and
emissions aftertreatment durability demonstration that are
significantly longer than required today.
As previously noted in this Section I, we received a large number
and wide range of comments on the proposed rule. Several comments
raised particularly significant issues related to some fundamental
components of the proposed program, including the level of the numeric
standards and feasibility of lower numeric standards combined with
longer useful life periods. We briefly discuss these key issues in this
Section I.B, with more detail in later sections in this preamble. The
Response to Comments document provides our responses to the comments we
received; it is located in the docket for this rulemaking.
1. Key Changes From the Proposal
i. Feasibility of More Stringent NOX Standards Combined With
Much Longer Useful Life Periods
Many stakeholders commented on the proposed numeric NOX
standards, and the feasibility of maintaining those numeric standards
over the proposed useful life periods. Environmental organizations and
other commenters, including suppliers to the heavy-duty industry,
generally urged EPA to adopt the most stringent standards proposed, or
to finalize even more stringent standards by fully aligning with the
California Air Resources Board (CARB) Low NOX Omnibus
program.\31\ In contrast, most engine manufacturers, truck dealers,
fleets, and other members of the heavy-duty industry stated that even
the less stringent proposed numeric standards and useful life periods
would be extremely challenging to meet, particularly for the largest
heavy-duty engines. Some of these commenters provided data that they
stated showed the potential for large impacts on the purchase price of
a new truck if EPA were to finalize the most stringent proposed numeric
standards and useful life periods for the largest heavy-duty engines.
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\31\ EPA is reviewing a waiver request under CAA section 209(b)
from California for the Omnibus rule. For more information on the
California Air Resources Board Omnibus rule see, ``Heavy-Duty Engine
and Vehicle Omnibus Regulation and Associated Amendments,'' December
22, 2021. https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.
Last accessed September 21, 2022. See also ``California State Motor
Vehicle Pollution Control Standards and Nonroad Engine Pollution
Control Standards; The ``Omnibus'' Low NOX Regulation;
Request for Waivers of Preemption; Opportunity for Public Hearing
and Public Comment'' at 87 FR 35765 (June 13, 2022).
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As summarized in I.B.2 and detailed in preamble Section III, we are
finalizing numeric NOX standards and useful life periods
that are largely consistent with the most stringent proposed option for
MY 2027. For all heavy-duty engine classes, the final numeric
NOX standards for medium- and high-load engine operations
match the most stringent standards proposed for MY 2027; for low-load
operations we are finalizing the most stringent standard proposed for
any model year (see I.B.1.ii for discussion).\32\ For smaller heavy-
duty engines (i.e., light and medium heavy-duty engines CI and SI
heavy-duty engines), the numeric standards are combined with the
longest useful life periods we proposed. The final numeric
NOX emissions standards and useful life periods for smaller
heavy-duty engines are based on further consideration of data included
in the proposal from our engine demonstration programs that show the
final NOX emissions standards are feasible at the final
useful life periods applicable to these smaller heavy-duty engines. Our
assessment of the data available at the time of proposal is further
supported by our evaluation of additional information and public
comments stating that the proposed standards are feasible for these
smaller engine categories. For the largest heavy-duty engines (i.e.,
heavy heavy-duty engines), the final numeric standards are combined
with the longest useful life mileage that we proposed for MY 2027. The
final useful life periods for the largest heavy-duty engines are 50
percent longer than today's useful life periods, which will play an
important role in ensuring continued emissions control while the
engines operate on the road.
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\32\ As proposed, we are finalizing a new test procedure for
heavy-duty CI engines to demonstrate emission control when the
engine is operating under low-load and idle conditions; this new
test procedure does not apply to heavy-duty SI engines (see Sections
I.B.2 and III for additional discussion).
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After further consideration of the data included in the proposal,
as well as information submitted by commenters and additional data we
collected since the time of proposal, we are finalizing two updates
from our proposed testing requirements in order to ensure the greatest
degree of emission reduction achievable are met throughout the final
useful life periods; these updates are tailored to the larger engine
classes (medium and heavy heavy-duty engines), which have longer useful
life periods and more rigorous duty-cycles compared to the smaller
engine classes. First, we are finalizing a requirement for
manufacturers to demonstrate before heavy heavy-duty engines are in-use
that the emissions control technology is durable through a period of
time longer than the final useful life mileage.\33\ For these largest
engines with the longest useful life mileages, the extended laboratory
durability demonstration will better ensure the final standards will be
met throughout the regulatory useful life
[[Page 4302]]
under real-world operations where conditions are more variable. Second,
we are finalizing an interim compliance allowance that applies when EPA
evaluates whether the heavy or medium heavy-duty engines are meeting
the final standards after these engines are in use in the real world.
When combined with the final useful life values, we believe the interim
compliance allowance will address concerns raised in comments from
manufacturers that the more stringent proposed MY 2027 standards would
not be feasible to meet over the very long useful life periods of heavy
heavy-duty engines, or under the challenging duty-cycles of medium
heavy-duty engines. This interim, in-use compliance allowance is
generally consistent with our past practice (for example, see 66 FR
5114, January 18, 2001); also consistent with past practice, the
interim compliance allowance is included as an interim provision that
we may reassess in the future through rulemaking based on the
performance of emissions controls over the final useful life periods
for medium and heavy heavy-duty engines. To set standards that result
in the greatest emission reductions achievable for medium and heavy
heavy-duty engines, we considered additional data that we and others
collected since the time of the proposal; these data show the
significant technical challenge of maintaining very low NOX
emissions throughout very long useful life periods for heavy heavy-duty
engines, and greater amounts of certain aging mechanisms over the long
useful life periods of medium heavy-duty engines. In addition to these
data, in setting these standards, we gave appropriate consideration to
costs associated with the application of technology to achieve maximum
emissions reductions in MY 2027 (i.e., cost of compliance for
manufacturers associated with the standards) and other factors. We
determined that for heavy heavy-duty engines the combination of: (1)
The most stringent MY 2027 standards proposed, (2) longer useful life
periods compared to today's useful life periods, (3) targeted, interim
compliance allowance approach to in-use compliance testing, and (4) the
extended durability demonstration for emissions control technologies is
appropriate, feasible, and consistent with our authority under the CAA
to set technology-forcing NOX pollutant standards for heavy-
duty engines for their useful life.\34\ Similarly, for medium heavy-
duty engines we determined that the combination of the first three
elements (i.e., most stringent MY 2027 standards proposed, increase in
useful life periods, and interim compliance allowance for in-use
testing) is appropriate, feasible, and consistent with our CAA
authority to set technology-forcing NOX pollutant standards
for heavy-duty engines for their useful life.
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\33\ Manufacturers of any size heavy-duty engine must
demonstrate that the emission control technology is durable through
a period equivalent to the useful life period of the engine, and may
be subject to recall if EPA subsequently determines that properly
maintained and used engines do not conform to our regulations over
the useful life period (as specified in our regulations and
consistent with CAA section 207). As outlined here, the extended
laboratory durability demonstration in the final program will
require manufacturers of the largest heavy-duty engines to
demonstrate emission control durability for a longer period to
better ensure that in-use engines will meet emission standards
throughout the long regulatory useful life of these engines.
\34\ CAA section 202(a)(3)(A) is a technology-forcing provision
and reflects Congress' intent that standards be based on projections
of future advances in pollution control capability, considering
costs and other statutory factors. See National Petrochemical &
Refiners Association v. EPA, 287 F.3d 1130, 1136 (D.C. Cir. 2002)
(explaining that EPA is authorized to adopt ``technology-forcing''
regulations under CAA section 202(a)(3)); NRDC v. Thomas, 805 F.2d
410, 428 n.30 (D.C. Cir. 1986) (explaining that such statutory
language that ``seek[s] to promote technological advances while also
accounting for cost does not detract from their categorization as
technology-forcing standards''); see also Husqvarna AB v. EPA, 254
F.3d 195 (D.C. Cir. 2001) (explaining that CAA sections 202 and 213
have similar language and are technology-forcing standards). In this
context, the term ``technology-forcing'' has a specific legal
meaning and is used to distinguish standards that may require
manufacturers to develop new technologies (or significantly improve
existing technologies) from standards that can be met using existing
off-the-shelf technology alone. Technology-forcing standards such as
those in this final rule do not require manufacturers to use
specific technologies.
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ii. Test Procedures To Control Emissions Under a Broader Range of
Engine Operations
Many commenters supported our proposal to update our test
procedures to more accurately account for and control emissions across
a broader range of engine operation, including in urban driving
conditions and other operations that could impact communities already
overburdened with pollution. Consistent with our proposal, we are
finalizing several provisions to reduce emissions from a broader range
of engine operating conditions. First, we are finalizing new standards
for our existing test procedures to reduce emissions under medium- and
high-load operations (e.g., when trucks are traveling on the highway).
Second, we are finalizing new standards and a corresponding new test
procedure to measure emissions during low-load operations (i.e., the
low-load cycle, LLC). Third, we are finalizing new standards and
updates to an existing test procedure to measure emissions over the
broader range of operations that occur when heavy-duty engines are
operating on the road (i.e., off-cycle). \35\
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\35\ Duty-cycle test procedures measure emissions while the
engine is operating over precisely defined duty cycles in an
emissions testing laboratory and provide very repeatable emission
measurements. ``Off-cycle'' test procedures measure emissions while
the engine is not operating on a specified duty cycle; this testing
can be conducted while the engine is being driven on the road (e.g.,
on a package delivery route), or in an emission testing laboratory.
Both duty-cycle and off-cycle testing are conducted pre-production
(e.g., for certification) or post-production to verify that the
engine meets applicable duty-cycle or off-cycle emission standards
throughout useful life (see Section III for more discussion).
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The new, more stringent numeric standards for the existing
laboratory-based test procedures that measure emissions during medium-
and high-load operations will ensure significant emissions reductions
from heavy-duty engines. Without this final rule, these medium- and
high-load operations are projected to contribute the most to heavy-duty
NOX emissions in 2045.
We are finalizing as proposed a new LLC test procedure, which will
ensure demonstration of emission control under sustained low-load
operations. After further consideration of data included in the
proposal, as well as additional information from the comments
summarized in this section, we are finalizing the most stringent
numeric LLC standard proposed for any model year. As discussed in our
proposal, data from our CI engine demonstration program showed that the
lowest numeric NOX standard proposed would be feasible for
the LLC throughout a useful life period similar to the useful life
period we are finalizing for the largest heavy-duty engines. After
further consideration of this data, and additional support from data
collected since the time of proposal, we are finalizing the most
stringent standard proposed for any model year.
We are finalizing new numeric standards and revisions to the
proposed off-cycle test procedure. We proposed updates to the current
off-cycle test procedure that included binning emissions measurements
based on the type of operation the engine is performing when the
measurement data is being collected. Specifically, we proposed that
emissions data would be grouped into three bins, based on whether the
engine was operating in idle (Bin 1), low-load (Bin 2), or medium-to-
high load (Bin 3). Given the different operational profiles of each of
the three bins, we proposed a separate standard for each bin. Based on
further consideration of data included in the proposal, as well as
additional support from our consideration of data provided by
commenters, we are finalizing off-cycle standards for two bins, rather
than three bins; correspondingly, we are finalizing a two-bin approach
for grouping emissions data collected during off-cycle test procedures.
Our evaluation of available information shows that two bins better
represent the
[[Page 4303]]
differences in engine operations that influence emissions (e.g.,
exhaust temperature, catalyst efficiency) and ensure sufficient data is
collected in each bin to allow for an accurate analysis of the data to
determine if emissions comply with the standard for each bin. Preamble
Section 0 further discusses the final off-cycle standards with
additional detail in preamble Section III.
iii. Lengthening Emissions-Related Warranty
EPA received general support from many commenters for the proposal
to lengthen the emissions-related warranty beyond existing
requirements. Some commenters expressed support for one of the proposed
options, and one organization suggested a warranty period even longer
than either proposed option. Several stakeholders also commented on the
costs of lengthened warranty periods and potential economic impacts.
For instance, one state commenter supported EPA's cost estimates and
agreed that the higher initial cost will be offset by lower repair
costs; further, the commenter expects the resale value of lengthened
warranty will be maintained for subsequent owners. In contrast,
stakeholders in the heavy-duty engine and truck industry (e.g., engine
and vehicle manufacturers, truck dealers, suppliers of emissions
control technologies) commented that the proposed warranty periods
would add costs to vehicles, and raised concerns about these cost
impacts on first purchasers. Many commenters indicated that purchase
price increases due to the longer warranty periods may delay emission
reductions, stating that high costs could incentivize pre-buy and
reduce fleet turnover from old technology.
After further consideration of data included in the proposal, and
consideration of additional supporting information from the comments
summarized in this Section I.B.1.iii, we are finalizing a single-step
increase for new, longer warranty periods to begin in MY 2027. Several
commenters recommended we pull ahead the longest proposed warranty
periods to start in MY 2027. We agree with that approach for the
smaller heavy-duty engine classes, and our final warranty mileages
match the longest proposed warranty periods for these smaller engines
(i.e., Spark-ignition HDE, Light HDE, and Medium HDE). However, we are
finalizing a different approach for the largest heavy-duty engines
(i.e., Heavy HDE). We are finalizing a warranty mileage that matches
the MY 2027 step of the most stringent proposed option to maximize the
emission control assurance and to cover a percentage of the final
useful life that is more consistent with the warranty periods of the
smaller engine classes. The final emissions warranty periods are
approximately two to four times longer than today's emissions warranty
periods. The durations of the final emissions warranty periods balance
two factors: First, the expected improvements in engine emission
performance from longer emissions warranty periods due to increases in
maintenance and lower rates of tampering with emissions controls (see
preamble Section IV.B for more discussion); and second, the potential,
particularly for the largest heavy-duty engines, for very large
increases in purchase price due to much longer warranty periods to slow
fleet turnover through increases in pre- and low-buy, and subsequently
result in fewer emissions reductions. We are finalizing emissions
warranty periods that in our evaluation will provide a significant
increase in the emissions warranty coverage while avoiding large
increases in the purchase price of a new truck.
iv. Model Year 2027 Single-Step Program
Many stakeholders expressed support for a single-step program to
implement new emissions standards and program requirements beginning in
model year 2027, which is consistent with one of the proposed options.
Stakeholders in the heavy-duty engine and truck industry, including
suppliers of emissions controls technologies, truck dealers, and engine
manufacturers, generally stated that a single-step program avoids
technology disruptions and allows industry to focus on research and
development for zero-emissions vehicle technologies for model years
beyond 2027. Some of these commenters further noted that a two-step
approach would result in gaps in available technology for some vehicle
types and could exacerbate slower fleet turnover from pre- and low-buy
associated with new standards. The trade association for truck dealers
noted that a two-step approach would significantly compromise expected
vehicle performance characteristics, including fuel economy. Other
commenters also generally supported a single-step approach in order for
the most stringent standards to begin as soon as possible, which would
lead to larger emissions reductions earlier than a two-step approach.
Several of these stakeholders noted the importance of early emissions
reductions in communities already overburdened with pollution.
The final NOX standards are a single-step program that
reflect the greatest emission reductions achievable starting in MY
2027, giving appropriate consideration to costs and other factors. In
this final rule, we are focused on achieving the greatest emission
reductions achievable in the MY 2027 timeframe, and have applied our
judgment in determining the appropriate standards for MY 2027 under our
CAA authority for a national program. As the heavy-duty industry
continues to transition to zero-emission technologies, EPA could
consider additional criteria pollutant standards for model years beyond
2027 in future rules.
v. Averaging, Banking, and Trading of NOX Emissions
The majority of stakeholders supported the proposed program to
allow averaging, banking, and trading (ABT) of NOX
emissions, although several suggested adjustments for EPA to consider
in the final rule. Stakeholders provided additional input on several
specific aspects of the proposed ABT program, including the proposed
family emissions limit (FEL) caps, the proposed Early Adoption
Incentives, and the proposed allowance for manufacturers to generate
NOX emissions credits from Zero Emissions Vehicles (ZEVs).
In this Section we briefly discuss stakeholder perspectives on these
specific aspects of the proposed ABT program, as well as our approach
for each in the final rule.
a. Family Emissions Limit Caps
A wide range of stakeholders urged EPA to finalize a lower FEL cap
than proposed; there was broad agreement that the FEL cap in the final
rule should be 100 mg/hp-hr or lower, with commenters citing various
considerations, such as the magnitude of reduction between the current
and proposed standards, as well as the desire to prevent competitive
disruption.
After further consideration, including consideration of public
comments, we are finalizing lower FEL caps than proposed. The FEL caps
in the final rule are 65 mg/hp-hr for MY 2027 through 2030, and 50 mg/
hp-hr for MY 2031 and later. Our rationale for the final FEL caps
includes two main factors. First, we agree with commenters that the
difference between the current standard (approximately 200 mg/hp-hr)
and the standards we are finalizing for MY 2027 and later suggests that
FEL caps lower than the current standard are
[[Page 4304]]
appropriate to ensure that available emissions control technologies are
adopted. This is consistent with our past practice when issuing rules
for heavy-duty onroad engines or nonroad engines in which there was a
substantial (e.g., greater than 50 percent) difference between the
numeric levels of the existing and new standards (69 FR 38997, June 29,
2004; 66 FR 5111, January 18, 2001). Specifically, by finalizing FEL
caps below the current standards, we are ensuring that the vast
majority of new engines introduced into commerce include updated
emissions control technologies compared to the emissions control
technologies manufacturers use to meet the current standards.\36\
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\36\ As discussed in Section IV.G.9, we are finalizing an
allowance for manufacturers to continue to produce a small number (5
percent of production volume) of engines that meet the current
standards for a few model years (i.e., through MY 2030); thus, the
vast majority of, but not all, new engines will need to include
updated emissions control technologies compared to those used to
meet today's standards until MY 2031, when all engines will need
updated emissions control technologies to comply with the final
standards or use credits up to the FEL cap. See Section IV.G.9 for
details on our approach and rationale for including this allowance
in the final rule.
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Second, finalizing FEL caps below the current standard is
consistent with comments from manufacturers stating that a FEL cap of
100 mg/hp-hr or between 50 and 100 mg/hp-hr would help to prevent
competitive disruptions (i.e., require all manufacturers to make
improvements in their emissions control technologies).
The FEL caps for the final rule have been set at a level to ensure
sizeable emission reductions from the current 2010 standards, while
providing manufacturers with flexibility in meeting the final
standards. When combined with the other restrictions in the final ABT
program (i.e., credit life, averaging sets, expiration of existing
credit balances), we determined the final FEL caps of 65 mg/hp-hr in
MYs 2027 through 2030, and 50 mg/hp-hr in MY 2031 and later avoid
potential adverse effects on the emissions reductions expected from the
final program.
b. Encouraging Early Adoption of New Emissions Controls Technologies
Several stakeholders provided general comments on the proposed
Early Adoption Incentive program, which included emissions credit
multipliers of 1.5 or 2.0 for meeting all proposed requirements prior
to the applicable model year. Although many of the stakeholders in the
heavy-duty engine industry generally supported incentives such as
emissions credit multipliers to encourage early investments in
emissions reductions technology; other industry stakeholders were
concerned that the multipliers would incentivize some technologies
(e.g., hybrid powertrains, natural gas engines) over others (e.g.,
battery-electric vehicles). Environmental organizations and other
commenters were concerned that the emissions credit multipliers would
result in an excess of credits that would undermine some of the
benefits of the rule.
After consideration of public comments, EPA is not finalizing the
proposed Early Adoption Incentives program, and in turn we are not
including emissions credit multipliers in the final program. Rather, we
are finalizing an updated version of the proposed transitional credit
program under the ABT program. As described in preamble Section IV.G.7,
the transitional credit program that we are finalizing provides four
pathways to generate straight NOX emissions credits (i.e.,
no credit multipliers) in order to encourage the early introduction
engines with NOX-reducing technology.
c. Heavy-Duty Zero Emissions Vehicles and NOX Emissions
Credits
Numerous stakeholders provided feedback on EPA's proposal to allow
manufacturers to generate NOX emissions credits from ZEVs.
Environmental organizations and other commenters, as well as suppliers
of heavy-duty engine and vehicle components, broadly oppose allowing
manufacturers to generate NOX emissions credits from ZEVs.
These stakeholders present several lines of argument, including the
potential for: (1) Substantial impacts on the emissions reductions
expected from the proposed rule, which could also result in
disproportionate impacts in disadvantaged communities already
overburdened with pollution; and (2) higher emissions from internal
combustion engines, rather than further incentives for additional ZEVs
(further noting that other State and Federal actions are providing more
meaningful and less environmentally costly HD ZEV incentives). In
contrast, heavy-duty engine and vehicle manufacturers generally support
allowing manufacturers to generate these credits. These stakeholders
also provided several lines of argument, including: (1) The potential
for ZEVs to help meet emissions reductions and air quality goals; (2)
an assertion that ZEV NOX credits are essential to the
achievability of the standards for some manufacturers; and (3) ZEV
NOX credits allow manufacturers to manage investments across
different products that may ultimately result in increased ZEV
deployment.
After further consideration, including consideration of public
comments, we are not finalizing the allowance for manufacturers to
generate NOX emissions credits from heavy-duty ZEVs. Our
decision is based on two primary considerations. First, the standards
in the final rule are technology-forcing, yet achievable for MY 2027
and later internal combustion engines without this flexibility. Second,
because the final standards are not based on projected utilization of
ZEV technology, and because we believe there will be increased
penetration of ZEVs in the heavy-duty fleet by MY 2027 and later,\37\
we are concerned that allowing ZEVs to generate NOX
emissions credits would result in fewer emissions reductions than
intended from this rule. For example, by allowing manufacturers to
generate ZEV NOX credits, EPA would be allowing higher
emissions (through internal combustion engines using credits to emit up
to the FEL cap) in MY 2027 and later, without requiring commensurate
emissions reductions (through additional ZEVs beyond those already
entering the market without this rule). This erosion of emissions
benefits could have particularly adverse impacts in communities already
overburdened by pollution. In addition, we continue to believe that
testing requirements to ensure continued battery and fuel cell
performance over the useful life of a ZEV may be important to ensure
the zero-emissions tailpipe performance for which they are generating
NOX credits; however, after further consideration, including
consideration of public comments, we believe it is appropriate to take
additional time to work with industry and other stakeholders on any
test procedures and other specifications for ZEV battery and fuel cell
performance over the useful life period of the ZEV.
---------------------------------------------------------------------------
\37\ For example, the recently passed Inflation Reduction Act
(IRA) has many incentives for promoting zero-emission vehicles, see
Sections 13403 (Qualified Clean Vehicles), 13404 (Alternative Fuel
Refueling Property Credit), 60101 (Clean Heavy-Duty Vehicles), 60102
(Grants to Reduce Air Pollution at Ports), and 70002 (United States
Postal Service Clean Fleets) of H. R. 5376.
---------------------------------------------------------------------------
2. Summary of the Key Provisions in the Regulatory Action
i. Controlling Criteria Pollutant Emissions Under a Broader Range of
Operating Conditions
The final rule provisions will reduce emissions from heavy-duty
engines
[[Page 4305]]
under a range of operating conditions through revisions to our
emissions standards and test procedures. These revisions will apply to
both laboratory-based standards and test procedures for both heavy-duty
CI and SI engines, as well as the off-cycle standards and test
procedures for heavy-duty CI engines. These final provisions are
outlined immediately below and detailed in Section III.
a. Final Laboratory Standards and Test Procedures
For heavy-duty CI engines, we are finalizing new standards for
laboratory-based tests using the current duty cycles, the transient
Federal Test Procedure (FTP) and the steady-state Supplemental Emission
Test (SET) procedure. These existing test procedures require CI engine
manufacturers to demonstrate the effectiveness of emission controls
when the engine is transitioning from low-to-high loads or operating
under sustained high load, but do not include demonstration of emission
control under sustained low-load operations. As proposed, we are
finalizing a new, laboratory-based LLC test procedure for heavy-duty CI
engines to demonstrate emission control when the engine is operating
under low-load and idle conditions. The addition of the LLC will help
ensure lower NOX emissions in urban areas and other
locations where heavy-duty vehicles operate in stop-and-go traffic or
other low-load conditions. As stated in Section I.B.1, we are
finalizing the most stringent standard proposed for any model year for
low-load operations based on further evaluation of data included in the
proposal, and supported by information received during the comment
period. We are also finalizing as proposed the option for manufacturers
to test hybrid engines and powertrains together using the final
powertrain test procedure.
For heavy-duty SI engines, we are finalizing new standards for
laboratory-based testing using the current FTP duty cycle, as well as
updates to the current engine mapping procedure to ensure the engines
achieve the highest torque level possible during testing. We are also
finalizing the proposed addition of the SET duty-cycle test procedure
to the heavy-duty SI laboratory demonstrations; it is currently only
required for heavy-duty CI engines. Heavy-duty SI engines are
increasingly used in larger heavy-duty vehicles, which makes it more
likely for these engines to be used in higher-load operations covered
by the SET.
Our final NOX emission standards for all defined duty
cycles for heavy-duty CI and SI engines are detailed in Table I-1. As
shown, the final NOX standards will be implemented with a
single step in MY 2027 and reflect the greatest emission reductions
achievable starting in MY 2027, giving appropriate consideration to
costs and other factors. As discussed in I.B.1.i, for the largest
heavy-duty engines we are finalizing two updates to our testing
requirements to ensure the greatest emissions reductions technically
achievable are met throughout the final useful life periods of the
largest heavy-duty engines: (1) A requirement for manufacturers to
demonstrate before heavy heavy-duty engines are in-use that the
emissions control technology are durable through a period of time
longer than the final useful mileage, and (2) a compliance allowance
that applies when EPA evaluates whether medium or heavy heavy-duty
engines are meeting the final standards after these engines are in-use
in the real world. We requested comment on an interim compliance
allowance, and it is consistent with our past practice (for example,
see 66 FR 5114, January 18, 2001); the interim compliance allowance is
shown in the final column of Table I-1. See Section III for more
discussion on feasibility of the final standards. Consistent with our
existing, MY 2010 standards for criteria pollutants, the final
standards, presented in Table 1, are numerically identical for SI and
CI engines.\38\
---------------------------------------------------------------------------
\38\ See Section III for our final PM, HC, and CO standards.
Table I-1--Final NOX Emission Standards for Heavy-Duty CI and SI Engines on Specific Duty Cycles
[milligrams/horsepower-hour (mg/hp-hr)]
----------------------------------------------------------------------------------------------------------------
Current Model years 2027 and later
-----------------------------------------------
Spark ignition Medium and
HDE, light heavy HDE with
All HD engines HDE, medium interim in-use
HDE, and heavy compliance
HDE allowance
----------------------------------------------------------------------------------------------------------------
Federal Test Procedure (transient mid/high load conditions)..... 200 35 50
Supplemental Emission Test (steady-state conditions)............ 200 35 50
Low Load Cycle (low-load conditions)............................ N/A 50 65
----------------------------------------------------------------------------------------------------------------
b. Final On-the-Road Standards and Test Procedures
In addition to demonstrating emission control over defined duty
cycles tested in a laboratory, heavy-duty CI engines must be able to
demonstrate emission control over operations experienced while engines
are in use on the road in the real world (i.e., ``off-cycle''
testing).\39\ We are finalizing with revisions the proposed updates to
the procedure for off-cycle testing, such that data collected during a
wider range of operating conditions will be valid, and therefore
subject to emission standards.
---------------------------------------------------------------------------
\39\ As discussed in Section III, ``off-cycle'' testing measures
emissions while the engine is not operating on a specified duty
cycle; this testing can be conducted while the engine is being
driven on the road (e.g., on a package delivery route), or in an
emission testing laboratory.
---------------------------------------------------------------------------
Similar to the current approach, emission measurements collected
during off-cycle testing will be collected on a second-by-second basis.
As proposed, we are finalizing that the emissions data will be grouped
into 300-second windows of operation. Each 300-second window will then
be binned based on the type of operation that the engine performs
during that 300-second period. Specifically, the average power of the
engine during each 300-second window will determine whether the
emissions during that window are binned as idle (Bin 1), or non-idle
(Bin 2).\40\
---------------------------------------------------------------------------
\40\ Due to the challenges of measuring engine power directly on
in-use vehicles, we are finalizing as proposed the use of the
CO2 emission rate (grams per second) as a surrogate for
engine power; further, we are finalizing as proposed to normalize
CO2 emission rates relative to the nominal maximum
CO2 rate of the engine (e.g., when an engine with a
maximum CO2 emission rate of 50 g/sec emits at a rate of
10 g/sec, its normalized CO2 emission rate is 20
percent).
---------------------------------------------------------------------------
[[Page 4306]]
Our final, two-bin approach covers a wide range of operations that
occur in the real world--significantly more in-use operation than
today's requirements. Bin 1 includes extended idle and other very low-
load operations, where engine exhaust temperatures may drop below the
optimal temperature where SCR-based aftertreatment works best. Bin 2
includes a large fraction of urban driving conditions, during which
engine exhaust temperatures are generally moderate, as well as higher-
power operations, such as on-highway driving, that typically results in
higher exhaust temperatures and high catalyst efficiencies.\41\ Given
the different operational profiles of each of these two bins, we are
finalizing, as proposed, a separate standard for each bin. As proposed,
the final structure follows that of our current not-to-exceed (NTE)
off-cycle standards where testing is conducted while the engine
operates on the road conducting its normal driving patterns, however,
the final standards apply over a much broader range of engine
operation.
---------------------------------------------------------------------------
\41\ Because the final approach considers time-averaged power,
either of the bins could include some idle operation and any of the
bins could include some high-power operation.
---------------------------------------------------------------------------
Table I-2 presents our final off-cycle standards for NOX
emissions from heavy-duty CI engines. As discussed in I.B.1.i, for the
medium and heavy heavy-duty engines we are also finalizing an interim
compliance allowance that applies to non-idle (Bin 2) off-cycle
standard after the engines are in-use. This interim compliance
allowance is consistent with our past practice (for example, see 66 FR
5114, January 18, 2001) and is shown in the final column of Table I-2.
See Section III for details on the final off-cycle standards for other
pollutants.
Table I-2--Final Off-Cycle NOX Standards for Heavy-Duty CI Engines \a\
------------------------------------------------------------------------
Model years 2027 and later
-------------------------------
Medium HDE and
Light HDE, heavy HDE with
medium HDE, in-use
heavy HDE compliance
allowance
------------------------------------------------------------------------
Bin 1: Idle (g/hr)...................... 10.0 \b\ 10.0
Bin 2: Low/medium/high load (mg/hp-hr).. 58 73
------------------------------------------------------------------------
\a\ The standards reflected in Table I-2 are applicable at 25 [deg]C and
above; at lower temperatures the numerical off-cycle Bin 1 and Bin 2
standards for NOX adjust as a function of ambient air temperature (see
preamble Section III.C for details).
\b\ The interim compliance allowance we are finalizing for medium and
heavy heavy-duty engines does not apply to the Bin 1 (Idle) off-cycle
standard (see preamble Section III for details).
In addition to the final standards for the defined duty cycle and
off-cycle test procedures, the final standards include several other
provisions for controlling emissions from specific operations in CI or
SI engines. First, we are finalizing, as proposed, to allow CI engine
manufacturers to voluntarily certify to idle standards using a new idle
test procedure that is based on an existing California Air Resources
Board (CARB) procedure.\42\
---------------------------------------------------------------------------
\42\ 13 CCR 1956.8 (a)(6)(C)--Optional NOX idling
emission standard.
---------------------------------------------------------------------------
We are also finalizing two options for manufacturers to control
engine crankcase emissions. Specifically, manufacturers will be
required to either: (1) As proposed, close the crankcase, or (2)
measure and account for crankcase emissions using an updated version of
the current requirements for an open crankcase. We believe that either
will ensure that the total emissions are accounted for during
certification testing and throughout the engine operation during useful
life. See Section III.B for more discussion on both the final idle and
crankcase provisions.
For heavy-duty SI, we are finalizing as proposed a new refueling
emission standard for incomplete vehicles above 14,000 lb GVWR starting
in MY 2027.\43\ The final refueling standard is based on the current
refueling standard that applies to complete heavy-duty gasoline-fueled
vehicles. Consistent with the current evaporative emission standards
that apply for these same vehicles, we are finalizing a requirement
that manufacturers can use an engineering analysis to demonstrate that
they meet our final refueling standard. We are also adopting an
optional alternative phase-in compliance pathway that manufacturers can
opt into in lieu of being subject to this implementation date for all
incomplete heavy-duty vehicles above 14,000 pounds GVWR (see Section
III.E for details).
---------------------------------------------------------------------------
\43\ Some vehicle manufactures sell their engines or
``incomplete vehicles'' (i.e., chassis that include their engines,
the frame, and a transmission) to body builders who design and
assemble the final vehicle.
---------------------------------------------------------------------------
ii. Ensuring Standards Are Met Over a Greater Portion of an Engine's
Operational Life
In addition to reducing emissions under a broad range of engine
operating conditions, the final program also includes provisions to
ensure emissions standards are met over a greater portion of an
engine's operational life. These final provisions include: (1)
Lengthened regulatory useful life periods for heavy-duty engines, (2)
revised requirement for the largest heavy-duty engines to demonstrate
that the emissions control technology is durable through a period of
time longer than the final useful life mileage, (3) updated methods to
more accurately and efficiently demonstrate the durability of emissions
controls, (4) lengthened emission warranty periods, and (5) increased
assurance that emission controls will be maintained properly through
more of the service life of heavy-duty engines. Each of these final
provisions is outlined immediately below and detailed in Section IV.
a. Final Useful Life Periods
Consistent with the proposal, the final useful life periods will
cover a significant portion of the engine's operational life.\44\ The
longer useful life periods, in combination with the durability
demonstration requirements we are finalizing in this rule, are expected
to lead manufacturers to further improve the durability of their
[[Page 4307]]
emission-related components. After additional consideration of data
included in the proposal, as well as additional data provided in public
comments, we are modifying our proposed useful life periods to account
for the combined effect of useful life and the final numeric standards
on the overall stringency and emissions reductions of the program (see
Section IV.A for additional details).
---------------------------------------------------------------------------
\44\ We consider operational life to be the average mileage at
rebuild for CI engines and the average mileage at replacement for SI
engines (see preamble Section IV.A for details).
---------------------------------------------------------------------------
For smaller heavy-duty engines (i.e., Spark-ignition HDE, Light
HDE, and Medium HDE) we are finalizing the longest useful life periods
proposed (i.e., MY 2031 step of proposed option 1), to apply starting
in MY 2027. The final useful life mileage for Heavy HDE, which has a
distinctly longer operational life than the smaller engine classes, is
approximately 50 percent longer than today's useful life mileage for
these engines and matches the longest useful life we proposed for MY
2027. Our final useful life periods for all heavy-duty engine classes
are presented in Table I-3. We are also increasing the years-based
useful life from the current 10 years to values that vary by engine
class and match the respective proposed options. After considering
comments, we are also adding hours-based useful life values to all
engine categories based on a 20 mile per hour speed threshold and the
corresponding final mileage values.\45\
---------------------------------------------------------------------------
\45\ As noted in this I.B.2, we are finalizing, as proposed,
refueling standards for certain HD SI engines that apply for a
useful life of 15 years or 150,000 miles. See 40 CFR 1037.103(f) and
preamble Section IV.A for more details.
Table I-3--Current and Final Useful Life Periods for Heavy-Duty CI and SI Engines
----------------------------------------------------------------------------------------------------------------
Current MY 2027 and later
Primary intended service class -----------------------------------------------------------------------------
Miles Years Hours Miles Years Hours
----------------------------------------------------------------------------------------------------------------
Spark-ignition HDE \a\............ 110,000 10 ........... 200,000 15 10,000
Light HDE \a\..................... 110,000 10 ........... 270,000 15 13,000
Medium HDE........................ 185,000 10 ........... 350,000 12 17,000
Heavy HDE \b\..................... 435,000 10 22,000 650,000 11 32,000
----------------------------------------------------------------------------------------------------------------
\a\ Current useful life period for Spark-ignition HDE and Light HDE for GHG emission standards is 15 years or
150,000 miles; we are not revising these useful life periods in this final rule. See 40 CFR 1036.108(d).
\b\ As discussed in Section I.B.2.ii.c, we are finalizing a requirement for manufacturers to demonstrate at the
time of certification that the emissions controls on these largest heavy-duty engines are durable through the
equivalent of 750,000 miles.
b. Extended Laboratory Demonstration of Emissions Control Durability
for the Largest Heavy-Duty Engines
As discussed in Section I.B.1.i, for the largest heavy-duty engines
we are finalizing two updates to our proposed testing requirements in
order to ensure the greatest emissions reductions technically
achievable are met throughout the final useful life periods of these
engines. One of the approaches (an in-use interim compliance allowance
for medium and heavy heavy-duty engines) was noted in Section I.B.2.i;
here we focus on the requirement for manufacturers to demonstrate
before the largest heavy-duty engines are in use that the emissions
control technology is durable through a period of time longer than the
final useful mileage. Specifically, we are finalizing a requirement for
manufacturers to demonstrate before the largest heavy-duty engines are
in use that the emissions controls on these engines are durable (e.g.,
capable of controlling NOX emissions over the FTP duty-cycle
at a level of 35 mg/hp-hr) through the equivalent of 750,000 miles. The
extended durability demonstration in a laboratory environment will
better ensure the final standards will be met throughout the longer
final regulatory useful life mileage of 650,000 miles when these
engines are operating in the real world where conditions are more
variable.\46\ As discussed immediately below in Section I.B.2.ii.c, we
are also finalizing provisions to improve the accuracy and efficiency
of emissions control durability demonstrations for all heavy-duty
engine classes.
---------------------------------------------------------------------------
\46\ Once these engines are in use, EPA can require
manufacturers to submit test data, or can conduct our own testing,
to verify that the emissions control technologies continue to
control emissions through the 650,000 mile useful life period (or
the equivalent hours or years requirements as applicable).
---------------------------------------------------------------------------
c. Final Durability Demonstration
EPA regulations require manufacturers to include durability
demonstration data as part of an application for certification of an
engine family. Manufacturers typically complete this demonstration by
following regulatory procedures to calculate a deterioration factor
(DF). The final useful life periods outlined in Table I-4 will require
manufacturers to extend their durability demonstrations to show that
the engines will meet applicable emission standards throughout the
lengthened useful life.
To address the need for accurate and efficient emission durability
demonstration methods, EPA worked with manufacturers and CARB to
address this concern through guidance for MY 2020 and later
engines.\47\ Consistent with the recent guidance, we proposed three
methods for determining DFs. We are finalizing two of the three
proposed methods; we are not finalizing the option to perform a fuel-
based accelerated DF determination, noting that it has been shown to
underestimate emission control system deterioration. The two methods we
are finalizing include: (1) Allowing manufacturers to continue the
current practice of determining DFs based on engine dynamometer-based
aging of the complete engine and aftertreatment system out to
regulatory useful life, and (2) a new option to bench-age the
aftertreatment system at an accelerated rate to limit the burden of
generating a DF over the final lengthened useful life periods. If
manufacturers choose the second option (accelerated bench-aging of the
aftertreatment system), then they may also choose to use an accelerated
aging test procedure that we are codifying in this final rule; the test
procedure is, based on a test program that we introduced in the
proposal to evaluate a rapid-aging protocol for diesel catalysts. We
are also finalizing with revisions two of the three proposed DF
verification options to confirm the accuracy of the DF values submitted
by manufacturers for certification. After further consideration of data
included in the proposal, as well as supported by
[[Page 4308]]
information provided in public comments, we are finalizing that, upon
EPA request, manufacturers would be required to provide confirmation of
the DF accuracy through one of two options.
---------------------------------------------------------------------------
\47\ U.S. EPA. ``Guidance on Deterioration Factor Validation
Methods for Heavy-Duty Diesel Highway Engines and Nonroad Diesel
Engines equipped with SCR.'' CD-2020-19 (HD Highway and Nonroad).
November 17, 2020.
---------------------------------------------------------------------------
d. Final Emission-Related Warranty Periods
We are updating and significantly strengthening the emission-
related warranty periods, for model year 2027 and later heavy-duty
engines.\48\ We are finalizing most of the emission-related warranty
provisions of 40 CFR 1036.120 as proposed. Following our approach for
useful life, we are revising the proposed warranty periods for each
primary intended service class to reflect the difference in average
operational life of each class and in consideration of the information
provided by commenters (see preamble Section IV and the Response to
Comments document for details).
---------------------------------------------------------------------------
\48\ Components installed to control only criteria pollutant
emissions or both greenhouse gas (i.e., CO2,
N2O, and CH4) and criteria pollutant emissions
would be subject to the final warranty periods of 40 CFR 1036.120.
See 40 CFR 1036.150(w).
---------------------------------------------------------------------------
EPA's current emissions-related warranty periods for heavy-duty
engines range from 22 percent to 54 percent of the current regulatory
useful life. Notably, these percent values have decreased over time
given that the warranty periods have not changed since 1983 even as the
useful life periods were lengthened.\49\ The revised warranty periods
are expected to result in better maintenance, including maintenance of
emission-related components, and less tampering, which would help to
ensure the benefits of the emission controls in-use. In addition,
longer regulatory warranty periods may lead engine manufacturers to
simplify repair processes and make them more aware of system defects
that need to be tracked and reported to EPA.
---------------------------------------------------------------------------
\49\ The useful life for heavy heavy-duty engines was increased
from 290,000 miles to 435,000 miles for 2004 and later model years
(62 FR 54694, October 21, 1997).
---------------------------------------------------------------------------
Our final emission-related warranty periods for heavy-duty engines
are presented in Table I-4. The final warranty mileages that apply
starting in MY 2027 for Spark-ignition HDE, Light HDE, and Medium HDE
match the longest warranty mileages proposed (i.e., MY 2031 step of
proposed Option 1) for these primary intended service classes. For
Heavy HDE, which has a distinctly longer operational life, the final
warranty mileage matches the longest warranty mileage proposed to apply
in MY 2027 (i.e., MY 2027 step of proposed Option 1), and is more than
four times longer than today's warranty mileage for these engines. We
are also increasing the years-based warranty from the current 5 years
to 10 years for all engine classes. After considering comments, we are
also adding hours-based warranty values to all primary intended service
classes based on a 20 mile per hour speed threshold and the
corresponding final mileage values. Consistent with current warranty
provisions, the warranty period would be whichever warranty value
(i.e., mileage, hours, or years) occurs first.
Table I-4--Current and Final Emission-Related Warranty Periods for Heavy-Duty CI and SI Engines Criteria
Pollutant Standards
----------------------------------------------------------------------------------------------------------------
Current Model year 2027 and later
Primary intended service class -----------------------------------------------------------------------------
Mileage Years Hours Mileage Years Hours
----------------------------------------------------------------------------------------------------------------
Spark-Ignition HDE................ 50,000 5 ........... 160,000 10 8,000
Light HDE......................... 50,000 5 ........... 210,000 10 10,000
Medium HDE........................ 100,000 5 ........... 280,000 10 14,000
Heavy HDE......................... 100,000 5 ........... 450,000 10 22,000
----------------------------------------------------------------------------------------------------------------
e. Provisions To Ensure Long-Term Emissions Performance
We proposed several approaches for an enhanced, comprehensive
strategy to increase the likelihood that emission controls will be
maintained properly through more of the operational life of heavy-duty
engines, including beyond their useful life periods. These approaches
include updated maintenance provisions, revised requirements for the
owner's manual and emissions label, codified engine derates or
``inducements'' regulations, and updated onboard diagnostics (OBD)
regulations.
Our final updates to maintenance provisions include defining the
type of maintenance manufacturers may choose to recommend to owners in
maintenance instructions, updating minimum maintenance intervals for
certain critical emission-related components, and outlining specific
requirements for maintenance instructions provided in the owner's
manual.
We are finalizing changes to the owner's manual and emissions label
requirements to ensure access to certain maintenance information and
improve serviceability. We expect this additional maintenance
information to improve factors that contribute to mal-maintenance,
which would result in better service experiences for independent repair
technicians, specialized repair technicians, owners who repair their
own equipment, and possibly vehicle inspection and maintenance
technicians. We also believe improving owner experiences with operating
and maintaining heavy-duty engines can reduce the likelihood of
tampering.
In addition, we are adopting inducement regulations that are an
update to and replace existing guidance regarding recommended methods
for manufacturers to reduce engine performance to induce operators to
maintain appropriate levels of high-quality diesel emission fluid (DEF)
in their SCR-based aftertreatment systems and discourage tampering with
such systems. See Section IV.D for details on the principles we
followed to develop multi-step derate schedules that are tailored to
different operating characteristics, as well as changes in the final
rule inducement regulations from the proposal.
We are also finalizing updated OBD regulations both to better
address newer diagnostic methods and available technologies, and to
streamline provisions where possible. We are incorporating by reference
the current CARB OBD regulations, updated in 2019, as proposed.\50\
Specifically, manufacturers must comply with OBD requirements as
referenced in the CARB
[[Page 4309]]
OBD regulations starting in model year 2027, with optional compliance
based on the CARB OBD regulations for earlier model years. After
considering comments, many of which included specific technical
information and requests for clarification, we are finalizing certain
provisions with revisions from proposal and postponing others for
consideration in a future rulemaking (see Section IV.C for details).
---------------------------------------------------------------------------
\50\ CARB's 2019 Heavy-duty OBD Final Regulation Order was
approved and became effective October 3, 2019. Title 13, California
Code of Regulations sections 1968.2, 1968.5, 1971.1, and 1971.5,
available at https://ww2.arb.ca.gov/rulemaking/2018/heavy-duty-board-diagnostic-system-requirements-2018.
---------------------------------------------------------------------------
iii. Averaging, Banking, and Trading of NOX Emissions
Credits
In addition the key program provisions, EPA is finalizing an
averaging, banking, and trading (ABT) program for heavy-duty engines
that provides manufacturers with flexibility in their product planning
while encouraging the early introduction of emissions control
technologies and maintaining the expected emissions reductions from the
program. Several core aspects of the final ABT program are consistent
with the proposal, but the final ABT program also includes several
updates after consideration of public comments. In particular, EPA
requested comment on and agrees with commenters that a lower family
emission limit (FEL) cap than proposed is appropriate for the final
rule. Further, after consideration of public comments, EPA is choosing
not to finalize at this time the proposed Early Adoption Incentives
program, and in turn we are not including emissions credit multipliers
in the final program. Rather, we are finalizing an updated version of
the proposed transitional credit program under the ABT program. The
revised transitional credit program that we are finalizing provides
four pathways to generate NOX emissions credits in MYs 2022
through 2026 that are valued based on the extent to which the engines
generating credits comply with the requirements we are finalizing for
MY 2027 and later (e.g., credits discounted at a rate of 40 percent for
engines meeting a lower numeric standard but none of the other MY 2027
and later requirements). Specifically, the four transitional credit
pathways in the final rule are: (1) In MY 2026, for heavy heavy-duty or
medium heavy-duty engine service classes, certify all engines in the
manufacturer's respective service class to a FEL of 50 mg/hp-hr or less
and meet all other EPA requirements for MYs 2027 and later to generate
undiscounted credits that have additional flexibilities for use in MYs
2027 and later (2026 Service Class Pull Ahead Credits); (2) starting in
MY 2024, certify one or more engine family(ies) to a FEL below the
current MY 2010 emissions standards and meet all other EPA requirements
for MYs 2027 and later to generate undiscounted credits based on the
longer UL periods included in the 2027 and later program (Full
Credits); (3) starting in MY 2024, certify one or more engine
family(ies) to a FEL below the current MY 2010 emissions standards and
several of the key requirements for MYs 2027 and later, while meeting
the current useful life and warranty requirements to generate
undiscounted credits based on the shorter UL period (Partial Credits);
(4) starting in MY 2022, certify one or more engine family(ies) to a
FEL below the current MY 2010 emissions standards, while complying with
all other MY2010 requirements, to generate discounted credits
(Discounted Credits). We note that the transitional credit and main ABT
program we are finalizing does not allow engines certified to state
standards that are different than the Federal EPA standards to generate
Federal EPA credits.
In addition, we are finalizing an optional production volume
allowance for MYs 2027 through 2029 that is consistent with our request
for comment in the proposal but different in several key aspects,
including a requirement for manufacturers to use NOX
emissions credits to certify heavy heavy-duty engines compliant with MY
2010 requirements in MYs 2027 through 2029. Finally, we have decided
not to finalize an allowance for manufacturers to generate
NOX emissions credits from heavy-duty ZEVs (see Section IV.G
for details on the final ABT program).
iv. Migration From 40 CFR Part 86, Subpart A
Heavy-duty criteria pollutant regulations were originally codified
into 40 CFR part 86, subpart A, in the 1980s. As discussed in the
proposal, this rulemaking provides an opportunity to clarify and
improve the wording of our existing heavy-duty criteria pollutant
regulations in plain language and migrate them to 40 CFR part 1036.\51\
Part 1036, which was created for the Phase 1 GHG program, provides a
consistent, updated format for our heavy-duty regulations, with
improved organization. In general, this migration is not intended to
change the compliance program specified in part 86, except as
specifically stated in this final rulemaking. See our summary of the
migration in Section III.A. The final provisions of part 1036 will
generally apply for model years 2027 and later, unless noted, and
manufacturers will continue to use part 86 in the interim.
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\51\ We are also adding and amending some provisions in parts
1065 and 1068 as part of the migration from part 86 for heavy-duty
highway engines; these provisions in part 1065 and 1068 will apply
to other sectors that are already subject to part 1065 and 1068.
Additionally, some current vehicle provisions in part 1037 refer to
part 86 and, as proposed, the final rule updates those references in
part 1037 as needed.
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v. Technical Amendments to Regulatory Provisions for Mobile Source
Sectors
EPA has promulgated emission standards for highway and nonroad
engines, vehicles, and equipment. Section XI of this final rule
describes several amendments to correct, clarify, and streamline a wide
range of regulatory provisions for many of those different types of
engines, vehicles, and equipment. Section XI.A includes technical
amendments to compliance provisions that apply broadly across EPA's
emission control programs to multiple industry sectors, including
light-duty vehicles, light-duty trucks, marine diesel engines,
locomotives, and various other types of nonroad engines, vehicles, and
equipment. Some of those amendments are for broadly applicable testing
and compliance provisions in 40 CFR parts 1065, 1066, and 1068. Other
cross-sector issues involve making the same or similar changes in
multiple standard-setting parts for individual industry sectors. The
rest of Section XI describes amendments we are finalizing that apply
uniquely for individual industry sectors. Except as specifically
identified in this rulemaking, EPA did not reopen any of the underlying
provisions across these standard setting parts.
We are finalizing amendments in two areas of note for the general
compliance provisions in 40 CFR part 1068. First, we are finalizing,
with updates from proposal, a comprehensive approach for making
confidentiality determinations related to compliance information that
companies submit to or is collected by EPA. These provisions apply for
highway, nonroad, and stationary engine, vehicle, and equipment
programs, as well as aircraft and portable fuel containers.
Second, we are finalizing, with updates from proposal, provisions
that include clarifying text to establish what qualifies as an
adjustable parameter and to identify the practically adjustable range
for those adjustable parameters. The adjustable-parameter provisions in
the final rule also include specific provisions related to electronic
controls that aim to deter tampering.
[[Page 4310]]
C. Impacts of the Standards
1. Projected Emission Reductions and Air Quality Improvements
Our analysis of the estimated emission reductions, air quality
improvements, costs, and monetized benefits of the final rule is
outlined in this section and detailed in Sections V through X. The
final standards, which are described in detail in Sections III and IV,
are expected to reduce emissions from highway heavy-duty engines in
several ways. We project the final emission standards for heavy-duty CI
engines will reduce tailpipe emissions of NOX; the
combination of the final low-load test cycle and off-cycle test
procedure for CI engines will help to ensure that the reductions in
tailpipe emissions are achieved in-use, not only under high-speed, on-
highway conditions, but also under low-load and idle conditions. We
also project reduced tailpipe emissions of NOX from the
final emission standards for heavy-duty SI engines, as well as
reductions of CO, PM, VOCs, and associated air toxics, particularly
under cold-start and high-load operating conditions. The final
emissions warranty and regulatory useful life requirements for heavy-
duty CI and SI engines will also help maintain emissions controls of
all pollutants beyond the existing useful life periods, which will
result in additional emissions reductions of all pollutants from both
CI and SI engines, including primary exhaust PM2.5. The
onboard refueling vapor recovery requirements for heavy-duty SI engines
will reduce VOCs and associated air toxics. Table I-5 summarizes the
projected reductions in heavy-duty emissions from the final standards
in 2045 and shows the significant reductions in NOX
emissions. Section VI and Regulatory Impact Analysis (RIA) Chapter 5
provide more information on our projected emission reductions for the
final rule.
Table I-5--Projected Heavy-Duty Emission Reductions in 2045 From the
Final Standards
------------------------------------------------------------------------
Percent
reduction in
Pollutant highway heavy-
duty emissions
(percent)
------------------------------------------------------------------------
NOX..................................................... 48
Primary PM2.5........................................... 8
VOC..................................................... 23
CO...................................................... 18
------------------------------------------------------------------------
The final standards will also reduce emissions of other pollutants.
For instance, the final rule will result in a 28 percent reduction in
benzene from highway heavy-duty engines in 2045. Leading up to 2045,
emission reductions are expected to increase over time as the fleet
turns over to new, compliant engines.
We expect this rule will decrease ambient concentrations of air
pollutants, including significant improvements in ozone concentrations
in 2045, as demonstrated in the air quality modeling analysis. We also
expect reductions in ambient PM2.5, NO2 and CO
due to this rule. The emission reductions provided by the final
standards will be important in helping areas attain and maintain the
NAAQS and prevent future nonattainment. This rule's emission reductions
will also reduce air pollution in close proximity to major roadways,
reduce nitrogen deposition and improve visibility.
Our consideration of environmental justice literature indicates
that people of color and people with low income are disproportionately
exposed to elevated concentrations of many pollutants in close
proximity to major roadways. We also used our air quality data from the
proposal to conduct a demographic analysis of human exposure to future
air quality in scenarios with and without the rule in place. Although
the spatial resolution of the air quality modeling is not sufficient to
capture very local heterogeneity of human exposures, particularly the
pollution concentration gradients near roads, the analysis does allow
estimates of demographic trends at a national scale. To compare
demographic trends, we sorted 2045 baseline air quality concentrations
from highest to lowest concentration and created two groups: Areas
within the contiguous United States with the worst air quality and the
rest of the country. We found that in the 2045 baseline, the number of
people of color living within areas with the worst air quality is
nearly double that of non-Hispanic Whites. We also found that the
largest predicted improvements in both ozone and PM2.5 are
estimated to occur in areas with the worst baseline air quality, where
larger numbers of people of color are projected to reside. An expanded
analysis of the air quality impacts experienced by specific race and
ethnic groups found that non-Hispanic Blacks will receive the greatest
improvement in PM2.5 and ozone concentrations as a result of
the standards. More details on our air quality modeling and demographic
analyses are included in Section VII and RIA Chapter 6.
2. Summary of Costs and Benefits
Our estimates of reductions in heavy-duty engine emissions and the
associated air quality impacts are based on manufacturers adding
emissions-reduction technologies and making emission control components
more durable in response to the final standards and longer regulatory
useful life periods; our estimates of emissions reductions also account
for improved repair of emissions controls by owners in response to the
longer emissions-related warranty periods and other provisions in the
final rule.
Our program cost analysis includes both the total technology costs
(i.e., manufacturers' costs to add or update emissions control
technologies) and the operating costs (i.e., owners' costs to maintain
and operate MY 2027 and later vehicles) (see Section V and RIA Chapter
7). Our evaluation of total technology costs of the final rule includes
direct costs (i.e., cost of materials, labor costs) and indirect
manufacturing costs (e.g., warranty, research and development). The
direct manufacturing costs include individual technology costs for
emission-related engine components and for exhaust aftertreatment
systems. Importantly, our analysis of direct manufacturing costs
includes the costs of the existing emission control technologies,
because we expect the emissions warranty and regulatory useful life
provisions in the final standards to have some impact on not only the
new technology added to comply with the standards, but also on any
existing emission control components. The cost estimates thus account
for existing engine hardware and aftertreatment systems for which new
costs will be incurred due to the new warranty and useful life
provisions, even absent any changes in the level of emission standards.
The indirect manufacturing costs in our analysis include the additional
costs--research and development, marketing, administrative costs,
etc.--incurred by manufacturers in running the company.
As part of our evaluation of operating costs, we estimate costs
truck owners incur to repair emission control system components. Our
repair cost estimates are based on industry data showing the amount
spent annually by truck owners on different types of repairs, and our
estimate of the percentage of those repairs that are related to
emission control components. Our analysis of this data shows that
extending the useful life and emission warranty periods will lower
emission repair costs during several years of operation for several
vehicle types. More discussion on our
[[Page 4311]]
emission repair costs estimates is included in Section V, with
additional details presented in RIA Chapter 7.
We combined our estimates of emission repair costs with other
operating costs (i.e., urea/DEF, fuel consumption) and technology costs
to calculate total program costs. Our analysis of the final standards
shows that total costs for the final program relative to the baseline
(or no action scenario) range from $3.9 billion in 2027 to $4.7 billion
in 2045 (2017 dollars, undiscounted, see Table V-16). The present value
of program costs for the final rule, and additional details are
presented in Section V.
Section VIII presents our analysis of the human health benefits
associated with the final standards. We estimate that in 2045, the
final rule will result in total annual monetized ozone- and
PM2.5-related benefits of $12 and $33 billion at a 3 percent
discount rate, and $10 and $30 billion at a 7 percent discount
rate.\52\ These benefits only reflect those associated with reductions
in NOX emissions (a precursor to both ozone and secondarily-
formed PM2.5) and directly-emitted PM2.5 from
highway heavy-duty engines.
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\52\ 2045 is a snapshot year chosen to approximate the annual
health benefits that occur when the final program will be fully
implemented and when most of the regulated fleet will have turned
over.
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There are additional human health and environmental benefits
associated with reductions in exposure to ambient concentrations of
PM2.5, ozone, and NO2 that EPA has not quantified
due to data, resource, or methodological limitations. There will also
be health benefits associated with reductions in air toxic pollutant
emissions that result from the final program, but we did not attempt to
quantify or monetize those impacts due to methodological limitations.
Because we were unable to quantify and monetize all of the benefits
associated with the final program, the monetized benefits presented in
this analysis are an underestimate of the program's total benefits.
More detailed information about the benefits analysis conducted for the
final rule, including the present value of program benefits, is
included in Section VIII and RIA Chapter 8.
We compare total monetized health benefits to total costs
associated with the final rule in Section IX. Table I-6 shows that
annual benefits of the final rule will be larger than the annual costs
in 2045, with annual net benefits of $6.9 and $29 billion assuming a 3
percent discount rate, and net benefits of $5.8 and $25 billion
assuming a 7 percent discount rate.\53\ The benefits of the final rule
also outweigh the costs when expressed in present value terms and as
equalized annual values (see Section IX for these values).\54\
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\53\ The range of benefits and net benefits reflects a
combination of assumed PM2.5 and ozone mortality risk
estimates and selected discount rate.
\54\ EPA's analysis of costs and benefits does not include
California's Omnibus rule or actions by other states to adopt it.
EPA is reviewing a waiver request under CAA section 209(b) from
California for the Omnibus rule; until EPA grants the waiver, the HD
Omnibus program is not enforceable. EPA's analysis also does not
include the recent IRA of 2022, which we anticipate will accelerate
zero emissions technology in the heavy-duty sector.
Table I-6--Final Costs, Benefits and Net Benefits in 2045
[billions, 2017$]
------------------------------------------------------------------------
3% Discount 7% Discount
------------------------------------------------------------------------
Benefits................................ $12-$33 $10-$30
Costs................................... $4.7 $4.7
Net Benefits............................ $6.9-$29 $5.8-$25
------------------------------------------------------------------------
3. Summary of Economic Impacts
Section X examines the potential impacts of the final rule on
heavy-duty vehicles (sales, mode shift, fleet turnover) and employment
in the heavy-duty industry. The final rule may impact vehicle sales due
to both changes in purchase price and longer emission warranty mileage
requirements. The final rule may impact vehicle sales by increasing
purchases of new vehicles before the final standards come into effect,
in anticipation of higher prices after the standards (``pre-buy''). The
final rule may also reduce sales after the final standards are in place
(``low-buy''). In this final rule, we outline an approach to quantify
potential impacts on vehicle sales due to new emission standards. Our
illustrative analysis for this final rule, discussed in RIA Chapter
10.1, suggest pre- and low-buy for Class 8 trucks may range from zero
to approximately 2 percent increase in sales over a period of up to 8
months before the 2027 standards begin (pre-buy), and a decrease in
sales from zero to approximately 3 percent over a period of up to 12
months after the 2027 standards begin (low-buy). We expect little mode
shift due to the final rule because of the large difference in cost of
moving goods via trucks versus other modes of transport (e.g., planes
or barges).
Employment impacts of the final rule depend on the effects of the
rule on sales, the share of labor in the costs of the rule, and changes
in labor intensity due to the rule. We quantify the effects of costs on
employment, and we discuss the effects due to sales and labor intensity
qualitatively. In response to comments, we have added a discussion in
Chapter 10 of the RIA describing a method that could be used to
quantitatively estimate a demand effect on employment, as well as an
illustrative application of that method. The partial quantification of
employment impacts due to increases in the costs of vehicles and parts,
holding labor intensity constant, shows an increase in employment by
1,000 to 5,300 job-years in 2027.\55\ See Section X for further detail
on limitations and assumptions of this analysis.
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\55\ A job-year is, for example, one year of full-time work for
one person, or one year of half-time work for two people.
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D. EPA Statutory Authority for This Action
This section briefly summarizes the statutory authority for the
final rule. Title II of the Clean Air Act provides for comprehensive
regulation of mobile sources, authorizing EPA to regulate emissions of
air pollutants from all mobile source categories. Specific Title II
authorities for this final rule include: CAA sections 202, 203, 206,
207, 208, 213, 216, and 301 (42 U.S.C. 7521, 7522, 7525, 7541, 7542,
7547, 7550, and 7601). We discuss some key aspects of these sections in
relation to this final action immediately below (see also Section XIII
of this preamble), as well as in each of the relevant sections later in
this preamble. As noted in Section I.B.2.v, the final rule includes
confidentiality determinations for much of the information collected by
EPA for certification and compliance under Title II; see Section XI.A.
for discussion of
[[Page 4312]]
relevant statutory authority for these final rule provisions.
Statutory authority for the final NOX, PM, HC, and CO
emission standards in this action comes from CAA section 202(a), which
states that ``the Administrator shall by regulation prescribe (and from
time to time revise) . . . standards applicable to the emission of any
air pollutant from any class or classes of new . . . motor vehicle
engines, which in his judgment cause, or contribute to, air pollution
which may reasonably be anticipated to endanger public health or
welfare.'' Standards under CAA section 202(a) take effect after such
period as the Administrator finds necessary to permit the development
and application of the requisite technology, giving appropriate
consideration to the cost of compliance within such period.''
Section 202(a)(3) further addresses EPA authority to establish
standards for emissions of NOX, PM, HC, and CO from heavy-
duty engines and vehicles. Section 202(a)(3)(A) requires that such
standards ``reflect the greatest degree of emission reduction
achievable through the application of technology which the
Administrator determines will be available for the model year to which
such standards apply, giving appropriate consideration to cost, energy,
and safety factors associated with the application of such
technology.'' Section 202(a)(3)(B) allows EPA to take into account air
quality information in revising such standards. Section 202(a)(3)(C)
provides that standards shall apply for a period of no less than three
model years beginning no earlier than the model year commencing four
years after promulgation. CAA section 202(a)(3)(A) is a technology-
forcing provision and reflects Congress' intent that standards be based
on projections of future advances in pollution control capability,
considering costs and other statutory factors.56 57 CAA
section 202(a)(3) neither requires that EPA consider all the statutory
factors equally nor mandates a specific method of cost-analysis; rather
EPA has discretion in determining the appropriate consideration to give
such factors.\58\
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\56\ See National Petrochemical & Refiners Association v. EPA,
287 F.3d 1130, 1136 (D.C. Cir. 2002) (explaining that EPA is
authorized to adopt ``technology-forcing'' regulations under CAA
section 202(a)(3)); NRDC v. Thomas, 805 F.2d 410, 428 n.30 (D.C.
Cir. 1986) (explaining that such statutory language that ``seek[s]
to promote technological advances while also accounting for cost
does not detract from their categorization as technology-forcing
standards''); see also Husqvarna AB v. EPA, 254 F.3d 195 (D.C. Cir.
2001) (explaining that CAA sections 202 and 213 have similar
language and are technology-forcing standards).
\57\ In this context, the term ``technology-forcing'' has a
specific legal meaning and is used to distinguish standards that may
require manufacturers to develop new technologies (or significantly
improve existing technologies) from standards that can be met using
off-the-shelf technology alone. Technology-forcing standards such as
those in this final rule do not require manufacturers to use
specific technologies.
\58\ See, e.g., Sierra Club v. EPA, 325 F.3d 374, 378 (D.C. Cir.
2003) (explaining that similar technology-forcing language in CAA
section 202(l)(2) ``does not resolve how the Administrator should
weigh all [the statutory] factors in the process of finding the
`greatest emission reduction achievable' ''); Husqvarna AB v. EPA,
254 F.3d 195, 200 (D.C. Cir. 2001) (explaining that under CAA
section 213's similar technology-forcing authority that ``EPA did
not deviate from its statutory mandate or frustrate congressional
will by placing primary significance on the `greatest degree of
emission reduction achievable' '' or by considering cost and other
statutory factors as important but secondary).
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CAA section 202(d) directs EPA to prescribe regulations under which
the useful life of vehicles and engines are determined and establishes
minimum values of 10 years or 100,000 miles, whichever occurs first,
unless EPA determines that a period of greater duration or mileage is
appropriate. EPA may apply adjustment factors to assure compliance with
requirements in use throughout useful life (CAA section 206(a)). CAA
section 207(a) requires manufacturers to provide emissions-related
warranty, which EPA last updated in its regulations for heavy-duty
engines in 1983 (see 40 CFR 86.085-2).\59\
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\59\ 48 FR 52170, November 16, 1983.
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EPA is promulgating the final emission standards pursuant to its
authority under CAA section 202(a), including 202(a)(3)(A). Section II
and Chapter 4 of the RIA describe EPA's analysis of information
regarding heavy-duty engines' contribution to air pollution and how
that pollution adversely impacts public health and welfare. Sections
III and IV discuss our feasibility analysis of the emission standards
and useful life periods in the final rule, with more detail in Chapter
3 of the RIA. Our analysis shows that the final emission standards and
useful life periods are feasible and will result in the greatest
emission reductions achievable for the model years to which they will
apply, pursuant to CAA section 202(a)(3), giving appropriate
consideration to costs, lead time, and other factors. Our analysis of
the final standards includes providing manufacturers with sufficient
time to ensure that emission control components are durable enough for
the longer useful life periods in the final program. In setting the
final emission standards, EPA appropriately assessed the statutory
factors specified in CAA section 202(a)(3)(A), including giving
appropriate consideration to the cost associated with the application
of technology EPA determined will be available for the model year the
final standards apply (i.e., cost of compliance for the manufacturer
associated with the application of such technology). EPA's assessment
of the relevant statutory factors in CAA section 202(a)(3)(A) justify
the final emission standards. We also evaluated additional factors,
including factors to comply with E.O. 12866; our assessment of these
factors lend further support to the final rule.
As proposed, we are finalizing new emission standards along with
new and revised test procedures for both laboratory-based duty-cycles
and off-cycle testing. Manufacturers demonstrate compliance over
specified duty-cycle test procedures during pre-production testing, as
well as confirmatory testing during production, which is conducted by
EPA or the manufacturer. Test data and other information submitted by
the manufacturer as part of their certification application are the
basis on which EPA issues certificates of conformity pursuant to CAA
section 206. Under CAA section 203, sales of new vehicles are
prohibited unless the vehicle is covered by a certificate of
conformity. Compliance with engine emission standards is required
throughout the regulatory useful life of the engine, not only at
certification but throughout the regulatory useful life in-use in the
real word. In-use engines can be tested for compliance with duty-cycle
and off-cycle standards, with testing over corresponding specific duty-
cycle test procedures and off-cycle test procedures, either on the road
or in the laboratory (see Section III for more discussion on for
testing at various stages in the life of an engine).
Also as proposed, we are finalizing lengthened regulatory useful
life and emission warranty periods to better reflect the mileages and
time periods over which heavy-duty engines are driven today. These and
other provisions in the final rule are further discussed in the
preamble sections that follow. The proposed rule (87 FR 17414, March
28, 2022) includes additional information relevant to the development
of this rule, including: History of Emissions Standards for Heavy-duty
Engines and Vehicles; Petitions to EPA for Additional NOX
control; the California Heavy-Duty Highway Low NOX Program
Development; and the Advance Notice of Proposed Rulemaking.
[[Page 4313]]
II. Need for Additional Emissions Control
This final rule will reduce emissions from heavy-duty engines that
contribute to ambient levels of ozone, PM, NOX and CO, which
are all pollutants for which EPA has established health-based NAAQS.
These pollutants are linked to premature death, respiratory illness
(including childhood asthma), cardiovascular problems, and other
adverse health impacts. Many groups are at greater risk than healthy
people from these pollutants, including people with heart or lung
disease, outdoor workers, older adults and children. These pollutants
also reduce visibility and negatively impact ecosystems. This final
rule will also reduce emissions of air toxics from heavy-duty engines.
A more detailed discussion of the health and environmental effects
associated with the pollutants affected by this rule is included in
Sections II.B and II.C and Chapter 4 of the RIA.
Populations who live, work, or go to school near high-traffic
roadways experience higher rates of numerous adverse health effects,
compared to populations far away from major roads. We note that there
is substantial evidence that people who live or attend school near
major roadways are more likely to be people of color, Hispanic
ethnicity, and/or low socioeconomic status.
Across the United States, NOX emissions from heavy-duty
engines are important contributors to concentrations of ozone and
PM2.5 and their resulting threat to public
health.60 61 The emissions modeling done for the final rule
(see Chapter 5 of the RIA) indicates that without these standards,
heavy-duty engines will continue to be one of the largest contributors
to mobile source NOX emissions nationwide in the future,
representing 32 percent of the mobile source NOX in calendar
year 2045.\62\ Furthermore, it is estimated that heavy-duty engines
would represent 90 percent of the onroad NOX inventory in
calendar year 2045.\63\ The emission reductions that will occur from
the final rule are projected to reduce air pollution that is (and is
projected to continue to be) at levels that endanger public health and
welfare. For the reasons discussed in this Section II, EPA concludes
that new standards are warranted to address the emissions of these
pollutants and their contribution to national air pollution. We note
that in the summer of 2016 more than 20 organizations, including state
and local air agencies from across the country, petitioned EPA to
develop more stringent NOX emission standards for on-road
heavy-duty engines.64 65 Among the reasons stated by the
petitioners for such an EPA rulemaking was the need for NOX
emission reductions to reduce adverse health and welfare impacts and to
help areas attain the NAAQS. EPA responded to the petitions on December
20, 2016, noting that an opportunity exists to develop a new national
NOX reduction strategy for heavy-duty highway engines.\66\
We subsequently initiated this rulemaking and issued an Advanced Notice
of Proposed Rulemaking in January 2020.\67\ This final rule culminates
the rulemaking proceeding and is responsive to those petitions.
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\60\ Zawacki et al., 2018. Mobile source contributions to
ambient ozone and particulate matter in 2025. Atmospheric
Environment, Vol 188, pg 129-141. Available online: https://doi.org/10.1016/j.atmosenv.2018.04.057.
\61\ Davidson et al., 2020. The recent and future health burden
of the U.S. mobile sector apportioned by source. Environmental
Research Letters. Available online: https://doi.org/10.1088/1748-9326/ab83a8.
\62\ Sectors other than onroad and nonroad were projected from
2016v1 Emissions Modeling Platform. https://www.epa.gov/air-emissions-modeling/2016v1-platform.
\63\ U.S. EPA (2020) Motor Vehicle Emission Simulator: MOVES3.
https://www.epa.gov/moves.
\64\ Brakora, Jessica. ``Petitions to EPA for Revised
NOX Standards for Heavy-Duty Engines'' Memorandum to
Docket EPA-HQ-OAR-2019-0055. December 4, 2019.
\65\ 87 FR 17414, March 28, 2022.
\66\ U.S. EPA. 2016. Memorandum in Response to Petition for
Rulemaking to Adopt Ultra-Low NOX Standards for On-
Highway Heavy-Duty Trucks and Engines. Available at https://19january2017snapshot.epa.gov/sites/production/files/2016-12/documents/nox-memorandum-nox-petition-response-2016-12-20.pdf.
\67\ The Agency published an ANPR on January 21, 2020 to present
EPA's early thinking on this rulemaking and solicit feedback from
stakeholders to inform this proposal (85 FR 3306).
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Many state and local agencies across the country commented on the
NPRM and have asked the EPA to reduce NOX emissions,
specifically from heavy-duty engines, because such reductions will be a
critical part of many areas' strategies to attain and maintain the
ozone and PM NAAQS. These state and local agencies anticipate
challenges in attaining the NAAQS, maintaining the NAAQS in the future,
and/or preventing nonattainment. Some nonattainment areas have already
been ``bumped up'' to higher classifications because of challenges in
attaining the NAAQS; others say they are struggling to avoid
nonattainment.\68\ Others note that the ozone and PM NAAQS are being
reconsidered so they could be made more stringent in the
future.69 70 Many state and local agencies commented on the
NPRM that heavy-duty vehicles are one of their largest sources of
NOX emissions. They commented that without action to reduce
emissions from heavy-duty vehicles, they will have to adopt other
potentially more burdensome and costly measures to reduce emissions
from other sources under their state or local authority, such as local
businesses. More information on the projected emission reductions and
air quality impacts that will result from this rule is provided in
Sections VI and VII.
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\68\ For example, in September 2019 several 2008 ozone
nonattainment areas were reclassified from moderate to serious,
including Dallas, Chicago, Connecticut, New York/New Jersey and
Houston, and in January 2020, Denver. Also, on September 15, 2022,
EPA finalized reclassification, bumping up 5 areas in nonattainment
of the 2008 ozone NAAQS from serious to severe and 22 areas in
nonattainment of the 2015 ozone NAAQS from marginal to moderate. The
2008 NAAQS for ozone is an 8-hour standard with a level of 0.075
ppm, which the 2015 ozone NAAQS lowered to 0.070 ppm.
\69\ https://www.epa.gov/ground-level-ozone-pollution/epa-reconsider-previous-administrations-decision-retain-2015-ozone.
\70\ https://www.epa.gov/pm-pollution/national-ambient-air-quality-standards-naaqs-pm.
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In their comments on the NPRM, many nonprofit groups, citizen
groups, individuals, and state, local, and Tribal organizations
emphasized the role that emissions from trucks have in harming
communities and that communities living near truck routes are
disproportionately people of color and those with lower incomes. They
supported additional NOX reductions from heavy-duty vehicles
to address concerns about environmental justice and ensuring that all
communities benefit from improvements in air quality. In addition, many
groups and commenters noted the link between emissions from heavy duty
trucks and harmful health effects, in particular asthma in children.
Commenters also supported additional NOX reductions from
heavy-duty vehicles to address concerns about regional haze, and damage
to terrestrial and aquatic ecosystems. They mentioned the impacts of
NOX emissions on numerous locations, such as the Chesapeake
Bay, Long Island Sound, the Rocky Mountains, Sierra Nevada Mountains,
Appalachian Mountains, Southwestern Desert ecosystems, and other areas.
For further detail regarding these comments and EPA's responses, see
Section 2 of the Response to Comments document for this rulemaking.
A. Background on Pollutants Impacted by This Proposal
1. Ozone
Ground-level ozone pollution forms in areas with high
concentrations of ambient nitrogen oxides (NOX) and
[[Page 4314]]
volatile organic compounds (VOCs) when solar radiation is strong. Major
U.S. sources of NOX are highway and nonroad motor vehicles,
engines, power plants and other industrial sources, with natural
sources, such as soil, vegetation, and lightning, serving as smaller
sources. Vegetation is the dominant source of VOCs in the United
States. Volatile consumer and commercial products, such as propellants
and solvents, highway and nonroad vehicles, engines, fires, and
industrial sources also contribute to the atmospheric burden of VOCs at
ground-level.
The processes underlying ozone formation, transport, and
accumulation are complex. Ground-level ozone is produced and destroyed
by an interwoven network of free radical reactions involving the
hydroxyl radical (OH), NO, NO2, and complex reaction
intermediates derived from VOCs. Many of these reactions are sensitive
to temperature and available sunlight. High ozone events most often
occur when ambient temperatures and sunlight intensities remain high
for several days under stagnant conditions. Ozone and its precursors
can also be transported hundreds of miles downwind, which can lead to
elevated ozone levels in areas with otherwise low VOC or NOX
emissions. As an air mass moves and is exposed to changing ambient
concentrations of NOX and VOCs, the ozone photochemical
regime (relative sensitivity of ozone formation to NOX and
VOC emissions) can change.
When ambient VOC concentrations are high, comparatively small
amounts of NOX catalyze rapid ozone formation. Without
available NOX, ground-level ozone production is severely
limited, and VOC reductions would have little impact on ozone
concentrations. Photochemistry under these conditions is said to be
``NOX-limited.'' When NOX levels are sufficiently
high, faster NO2 oxidation consumes more radicals, dampening
ozone production. Under these ``VOC-limited'' conditions (also referred
to as ``NOX-saturated'' conditions), VOC reductions are
effective in reducing ozone, and NOX can react directly with
ozone, resulting in suppressed ozone concentrations near NOX
emission sources. Under these NOX-saturated conditions,
NOX reductions can actually increase local ozone under
certain circumstances, but overall ozone production (considering
downwind formation) decreases. Even in VOC-limited areas,
NOX reductions are not expected to increase ozone levels if
the NOX reductions are sufficiently large--large enough to
become NOX-limited.
The primary NAAQS for ozone, established in 2015 and retained in
2020, is an 8-hour standard with a level of 0.07 ppm.\71\ EPA announced
that it will reconsider the decision to retain the ozone NAAQS.\72\ The
EPA is also implementing the previous 8-hour ozone primary standard,
set in 2008, at a level of 0.075 ppm. As of August 31, 2022, there were
34 ozone nonattainment areas for the 2008 ozone NAAQS, composed of 141
full or partial counties, with a population of more than 90 million,
and 49 ozone nonattainment areas for the 2015 ozone NAAQS, composed of
212 full or partial counties, with a population of more than 125
million. In total, there are currently, as of August 31, 2022, 57 ozone
nonattainment areas with a population of more than 130 million
people.\73\
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\71\ https://www.epa.gov/ground-level-ozone-pollution/ozone-national-ambient-air-quality-standards-naaqs.
\72\ https://www.epa.gov/ground-level-ozone-pollution/epa-reconsider-previous-administrations-decision-retain-2015-ozone.
\73\ The population total is calculated by summing, without
double counting, the 2008 and 2015 ozone nonattainment populations
contained in the Criteria Pollutant Nonattainment Summary report
(https://www.epa.gov/green-book/green-book-data-download).
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States with ozone nonattainment areas are required to take action
to bring those areas into attainment. The attainment date assigned to
an ozone nonattainment area is based on the area's classification. The
attainment dates for areas designated nonattainment for the 2008 8-hour
ozone NAAQS are in the 2015 to 2032 timeframe, depending on the
severity of the problem in each area. Attainment dates for areas
designated nonattainment for the 2015 ozone NAAQS are in the 2021 to
2038 timeframe, again depending on the severity of the problem in each
area.\74\ The final NOX standards will take effect starting
in MY 2027 and will assist areas with attaining the NAAQS and may
relieve areas with already stringent local regulations from some of the
burden associated with adopting additional local controls.\75\ The rule
will also provide assistance to counties with ambient concentrations
near the level of the NAAQS who are working to ensure long-term
attainment or maintenance of the NAAQS.
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\74\ https://www.epa.gov/ground-level-ozone-pollution/ozone-naaqs-timelines.
\75\ While not quantified in the air quality modeling analysis
for this rule, elements of the Averaging, Banking, and Trading (ABT)
program could encourage manufacturers to introduce new emission
control technologies prior to the 2027 model year, which may help to
accelerate some emission reductions of the final rule (See Preamble
Section IV.G for more details on the ABT program in the final rule).
In RIA Chapter 5.5 we also include a sensitivity analysis that shows
allowing manufacturers to generate NOX emissions credits
by meeting requirements of the final rule one model year before
required would lead to meaningful, additional reductions in
NOX emissions in the early years of the program compared
to the emissions reductions expected from the final rule (see
preamble Section IV.G.7 and RIA Chapter 5.5 for additional details).
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2. Particulate Matter
Particulate matter (PM) is a complex mixture of solid particles and
liquid droplets distributed among numerous atmospheric gases which
interact with solid and liquid phases. Particles in the atmosphere
range in size from less than 0.01 to more than 10 micrometers ([mu]m)
in diameter.\76\ Atmospheric particles can be grouped into several
classes according to their aerodynamic diameter and physical sizes.
Generally, the three broad classes of particles include ultrafine
particles (UFPs, generally considered as particles with a diameter less
than or equal to 0.1 [mu]m [typically based on physical size, thermal
diffusivity or electrical mobility]), ``fine'' particles
(PM2.5; particles with a nominal mean aerodynamic diameter
less than or equal to 2.5 [mu]m), and ``thoracic'' particles
(PM10; particles with a nominal mean aerodynamic diameter
less than or equal to 10 [mu]m). Particles that fall within the size
range between PM2.5 and PM10, are referred to as
``thoracic coarse particles'' (PM10-2.5,
particles with a nominal mean aerodynamic diameter greater than 2.5
[mu]m and less than or equal to 10 [mu]m). EPA currently has NAAQS for
PM2.5 and PM10.\77\
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\76\ U.S. EPA. Policy Assessment (PA) for the Review of the
National Ambient Air Quality Standards for Particulate Matter (Final
Report, 2020). U.S. Environmental Protection Agency, Washington, DC,
EPA/452/R-20/002, 2020.
\77\ Regulatory definitions of PM size fractions, and
information on reference and equivalent methods for measuring PM in
ambient air, are provided in 40 CFR parts 50, 53, and 58. With
regard to NAAQS which provide protection against health and welfare
effects, the 24-hour PM10 standard provides protection
against effects associated with short-term exposure to thoracic
coarse particles (i.e., PM10-2.5).
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Most particles are found in the lower troposphere, where they can
have residence times ranging from a few hours to weeks. Particles are
removed from the atmosphere by wet deposition, such as when they are
carried by rain or snow, or by dry deposition, when particles settle
out of suspension due to gravity. Atmospheric lifetimes are generally
longest for PM2.5, which often remains in the atmosphere for
days to weeks before being removed by wet or dry deposition.\78\ In
contrast,
[[Page 4315]]
atmospheric lifetimes for UFP and PM10-2.5 are
shorter. Within hours, UFP can undergo coagulation and condensation
that lead to formation of larger particles, or can be removed from the
atmosphere by evaporation, deposition, or reactions with other
atmospheric components. PM10-2.5 are also
generally removed from the atmosphere within hours, through wet or dry
deposition.\79\
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\78\ U.S. EPA. Integrated Science Assessment (ISA) for
Particulate Matter (Final Report, 2019). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019. Table 2-
1.
\79\ U.S. EPA. Integrated Science Assessment (ISA) for
Particulate Matter (Final Report, 2019). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019. Table 2-
1.
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Particulate matter consists of both primary and secondary
particles. Primary particles are emitted directly from sources, such as
combustion-related activities (e.g., industrial activities, motor
vehicle operation, biomass burning), while secondary particles are
formed through atmospheric chemical reactions of gaseous precursors
(e.g., sulfur oxides (SOX), NOX, and VOCs).
There are two primary NAAQS for PM2.5: An annual
standard (12.0 micrograms per cubic meter ([mu]g/m\3\)) and a 24-hour
standard (35 [mu]g/m\3\), and there are two secondary NAAQS for
PM2.5: An annual standard (15.0 [mu]g/m\3\) and a 24-hour
standard (35 [mu]g/m\3\). The initial PM2.5 standards were
set in 1997 and revisions to the standards were finalized in 2006 and
in December 2012 and then retained in 2020. On June 10, 2021, EPA
announced that it will reconsider the decision to retain the PM
NAAQS.\80\
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\80\ https://www.epa.gov/pm-pollution/national-ambient-air-quality-standards-naaqs-pm.
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There are many areas of the country that are currently in
nonattainment for the annual and 24-hour primary PM2.5
NAAQS. As of August 31, 2022, more than 19 million people lived in the
4 areas that are designated as nonattainment for the 1997
PM2.5 NAAQS. Also, as of August 31, 2022, more than 31
million people lived in the 14 areas that are designated as
nonattainment for the 2006 PM2.5 NAAQS and more than 20
million people lived in the 5 areas designated as nonattainment for the
2012 PM2.5 NAAQS. In total, there are currently 15
PM2.5 nonattainment areas with a population of more than 32
million people.\81\ The final NOX standards will take effect
in MY 2027 and will assist areas with attaining the NAAQS and may
relieve areas with already stringent local regulations from some of the
burden associated with adopting additional local controls.\82\ The rule
will also assist counties with ambient concentrations near the level of
the NAAQS who are working to ensure long-term attainment or maintenance
of the PM2.5 NAAQS.
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\81\ The population total is calculated by summing, without
double counting, the 1997, 2006 and 2012 PM2.5
nonattainment populations contained in the Criteria Pollutant
Nonattainment Summary report (https://www.epa.gov/green-book/green-book-data-download).
\82\ While not quantified in the air quality modeling analysis
for this rule, elements of the Averaging, Banking, and Trading (ABT)
program could encourage manufacturers to introduce new emission
control technologies prior to the 2027 model year, which may help to
accelerate some emission reductions of the final rule (See Preamble
Section IV.G for more details on the ABT program in the final rule).
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3. Nitrogen Oxides
Oxides of nitrogen (NOX) refers to nitric oxide (NO) and
nitrogen dioxide (NO2). Most NO2 is formed in the
air through the oxidation of NO emitted when fuel is burned at a high
temperature. NO2 is a criteria pollutant, regulated for its
adverse effects on public health and the environment, and highway
vehicles are an important contributor to NO2 emissions.
NOX, along with VOCs, are the two major precursors of ozone
and NOX is also a major contributor to secondary
PM2.5 formation. There are two primary NAAQS for
NO2: An annual standard (53 ppb) and a 1-hour standard (100
ppb).\83\ In 2010, EPA established requirements for monitoring
NO2 near roadways expected to have the highest
concentrations within large cities. Monitoring within this near-roadway
network began in 2014, with additional sites deployed in the following
years. At present, there are no nonattainment areas for NO2.
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\83\ The statistical form of the 1-hour NAAQS for NO2
is the 3-year average of the yearly distribution of 1-hour daily
maximum concentrations.
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4. Carbon Monoxide
Carbon monoxide (CO) is a colorless, odorless gas emitted from
combustion processes. Nationally, particularly in urban areas, the
majority of CO emissions to ambient air come from mobile sources.\84\
There are two primary NAAQS for CO: An 8-hour standard (9 ppm) and a 1-
hour standard (35 ppm). There are currently no CO nonattainment areas;
as of September 27, 2010, all CO nonattainment areas have been
redesignated to attainment. The past designations were based on the
existing community-wide monitoring network. EPA made an addition to the
ambient air monitoring requirements for CO during the 2011 NAAQS
review. Those new requirements called for CO monitors to be operated
near roads in Core Based Statistical Areas (CBSAs) of 1 million or more
persons, in addition to the existing community-based network (76 FR
54294, August 31, 2011).
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\84\ U.S. EPA, (2010). Integrated Science Assessment for Carbon
Monoxide (Final Report). U.S. Environmental Protection Agency,
Washington, DC, EPA/600/R-09/019F, 2010. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=218686. See Section 2.1.
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5. Diesel Exhaust
Diesel exhaust is a complex mixture composed of particulate matter,
carbon dioxide, oxygen, nitrogen, water vapor, carbon monoxide,
nitrogen compounds, sulfur compounds and numerous low-molecular-weight
hydrocarbons. A number of these gaseous hydrocarbon components are
individually known to be toxic, including aldehydes, benzene and 1,3-
butadiene. The diesel particulate matter present in diesel exhaust
consists mostly of fine particles (<2.5 [mu]m), of which a significant
fraction is ultrafine particles (<0.1 [mu]m). These particles have a
large surface area which makes them an excellent medium for adsorbing
organics and their small size makes them highly respirable. Many of the
organic compounds present in the gases and on the particles, such as
polycyclic organic matter, are individually known to have mutagenic and
carcinogenic properties.
Diesel exhaust varies significantly in chemical composition and
particle sizes between different engine types (heavy-duty, light-duty),
engine operating conditions (idle, acceleration, deceleration), and
fuel formulations (high/low sulfur fuel). Also, there are emissions
differences between on-road and nonroad engines because the nonroad
engines are generally of older technology. After being emitted in the
engine exhaust, diesel exhaust undergoes dilution as well as chemical
and physical changes in the atmosphere. The lifetime of the components
present in diesel exhaust ranges from seconds to days.
Because diesel particulate matter (DPM) is part of overall ambient
PM, varies considerably in composition, and lacks distinct chemical
markers that enable it to be easily distinguished from overall primary
PM, we do not have direct measurements of DPM in the ambient air.\85\
DPM concentrations are
[[Page 4316]]
estimated using ambient air quality modeling based on DPM emission
inventories. DPM emission inventories are computed as the exhaust PM
emissions from mobile sources combusting diesel or residual oil fuel.
DPM concentrations were estimated as part of the 2018 national Air
Toxics Screening Assessment (AirToxScreen).\86\ Areas with high
concentrations are clustered in the Northeast and Great Lake States,
with a smaller number of higher concentration locations in Western
states. The highest impacts occur in major urban cores, and are also
distributed throughout the rest of the United States near high truck
traffic, coasts with marine diesel activity, construction sites, and
rail facilities. Approximately half of the average ambient DPM
concentration in the United States can be attributed to heavy-duty
diesel engines, with the remainder attributable to nonroad engines.
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\85\ DPM in exhaust from a high-load, high-speed engine (e.g.,
heavy-duty truck engines) without aftertreatment such as a diesel
particle filter (DPM) is mostly made of ``soot,'' consisting of
elemental/black carbon (EC/BC), some organic material, and trace
elements. At low loads, DPM in high-speed engine exhaust is mostly
made of organic carbon (OC), with considerably less EC/BC. Low-speed
diesel engines' (e.g., large marine engines) exhaust PM is comprised
of more sulfate and less EC/BC, with OC contributing as well.
\86\ U.S. EPA (2022) Technical Support Document EPA Air Toxics
Screening Assessment. 2018AirToxScreen TSD. https://www.epa.gov/AirToxScreen/airtoxscreen-technical-support-document.
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6. Air Toxics
The most recent available data indicate that millions of Americans
live in areas where air toxics pose potential health concerns.\87\ The
levels of air toxics to which people are exposed vary depending on
where people live and work and the kinds of activities in which they
engage, as discussed in detail in EPA's 2007 Mobile Source Air Toxics
Rule.\88\ According to EPA's Air Toxics Screening Assessment
(AirToxScreen) for 2018, mobile sources were responsible for 40 percent
of outdoor anthropogenic toxic emissions and were the largest
contributor to national average cancer and noncancer risk from directly
emitted pollutants.89 90 Mobile sources are also significant
contributors to precursor emissions which react to form air toxics.\91\
Formaldehyde is the largest contributor to cancer risk of all 71
pollutants quantitatively assessed in the 2018 AirToxScreen. Mobile
sources were responsible for 26 percent of primary anthropogenic
emissions of this pollutant in 2018 and are significant contributors to
formaldehyde precursor emissions. Benzene is also a large contributor
to cancer risk, and mobile sources account for about 60 percent of
average exposure to ambient concentrations.
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\87\ U.S. EPA (2022) Technical Support Document EPA Air Toxics
Screening Assessment. 2017AirToxScreen TSD. https://www.epa.gov/system/files/documents/2022-03/airtoxscreen_2017tsd.pdf.
\88\ U.S. Environmental Protection Agency (2007). Control of
Hazardous Air Pollutants from Mobile Sources; Final Rule. 72 FR
8434, February 26, 2007.
\89\ U.S. EPA. (2022) Air Toxics Screening Assessment. https://www.epa.gov/AirToxScreen/2018-airtoxscreen-assessment-results.
\90\ AirToxScreen also includes estimates of risk attributable
to background concentrations, which includes contributions from
long-range transport, persistent air toxics, and natural sources; as
well as secondary concentrations, where toxics are formed via
secondary formation. Mobile sources substantially contribute to
long-range transport and secondarily formed air toxics.
\91\ Rich Cook, Sharon Phillips, Madeleine Strum, Alison Eyth &
James Thurman (2020): Contribution of mobile sources to secondary
formation of carbonyl compounds, Journal of the Air & Waste
Management Association, DOI: 10.1080/10962247.2020.1813839.
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B. Health Effects Associated With Exposure to Pollutants Impacted by
This Rule
Heavy-duty engines emit pollutants that contribute to ambient
concentrations of ozone, PM, NO2, CO, and air toxics. This
section of the preamble discusses the health effects associated with
exposure to these pollutants.
Additionally, because children have increased vulnerability and
susceptibility for adverse health effects related to air pollution
exposures, EPA's findings regarding adverse effects for children
related to exposure to pollutants that are impacted by this rule are
noted in this section. The increased vulnerability and susceptibility
of children to air pollution exposures may arise because infants and
children generally breathe more relative to their size than adults do,
and consequently may be exposed to relatively higher amounts of air
pollution.\92\ Children also tend to breathe through their mouths more
than adults and their nasal passages are less effective at removing
pollutants, which leads to greater lung deposition of some pollutants,
such as PM.93 94 Furthermore, air pollutants may pose health
risks specific to children because children's bodies are still
developing.\95\ For example, during periods of rapid growth such as
fetal development, infancy, and puberty, their developing systems and
organs may be more easily harmed.96 97 EPA's America's
Children and the Environment is a tool which presents national trends
on air pollutants and other contaminants and environmental health of
children.\98\
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\92\ EPA (2009) Metabolically-derived ventilation rates: A
revised approach based upon oxygen consumption rates. Washington,
DC: Office of Research and Development. EPA/600/R-06/129F. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=202543.
\93\ U.S. EPA Integrated Science Assessment for Particulate
Matter (Final Report, 2019). U.S. Environmental Protection Agency,
Washington, DC, EPA/600/R-19/188, 2019. Chapter 4 ``Overall
Conclusions'' p. 4-1.
\94\ Foos, B.; Marty, M.; Schwartz, J.; Bennet, W.; Moya, J.;
Jarabek, A.M.; Salmon, A.G. (2008) Focusing on children's inhalation
dosimetry and health effects for risk assessment: An introduction. J
Toxicol Environ Health 71A: 149-165.
\95\ Children's environmental health includes conception,
infancy, early childhood and through adolescence until 21 years of
age as described in the EPA Memorandum: Issuance of EPA's 2021
Policy on Children's Health. October 5, 2021. Available at https://www.epa.gov/system/files/documents/2021-10/2021-policy-on-childrens-health.pdf.
\96\ EPA (2006) A Framework for Assessing Health Risks of
Environmental Exposures to Children. EPA, Washington, DC, EPA/600/R-
05/093F, 2006.
\97\ U.S. Environmental Protection Agency. (2005). Supplemental
guidance for assessing susceptibility from early-life exposure to
carcinogens. Washington, DC: Risk Assessment Forum. EPA/630/R-03/
003F. https://www3.epa.gov/airtoxics/childrens_supplement_final.pdf.
\98\ U.S. EPA. America's Children and the Environment. Available
at: https://www.epa.gov/americaschildrenenvironment.
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Information on environmental effects associated with exposure to
these pollutants is included in Section II.C, and information on
environmental justice is included in Section VII.H. Information on
emission reductions and air quality impacts from this rule are included
in Section VI and VII.
1. Ozone
This section provides a summary of the health effects associated
with exposure to ambient concentrations of ozone.\99\ The information
in this section is based on the information and conclusions in the
April 2020 Integrated Science Assessment for Ozone (Ozone ISA).\100\
The Ozone ISA concludes that human exposures to ambient concentrations
of ozone are associated with a number of adverse health effects and
characterizes the weight of evidence for these health effects.\101\ The
following discussion highlights the Ozone ISA's
[[Page 4317]]
conclusions pertaining to health effects associated with both short-
term and long-term periods of exposure to ozone.
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\99\ Human exposure to ozone varies over time due to changes in
ambient ozone concentration and because people move between
locations which have notably different ozone concentrations. Also,
the amount of ozone delivered to the lung is influenced not only by
the ambient concentrations but also by the breathing route and rate.
\100\ U.S. EPA. Integrated Science Assessment (ISA) for Ozone
and Related Photochemical Oxidants (Final Report). U.S.
Environmental Protection Agency, Washington, DC, EPA/600/R-20/012,
2020.
\101\ The ISA evaluates evidence and draws conclusions on the
causal relationship between relevant pollutant exposures and health
effects, assigning one of five ``weight of evidence''
determinations: causal relationship, likely to be a causal
relationship, suggestive of a causal relationship, inadequate to
infer a causal relationship, and not likely to be a causal
relationship. For more information on these levels of evidence,
please refer to Table II in the Preamble of the ISA.
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For short-term exposure to ozone, the Ozone ISA concludes that
respiratory effects, including lung function decrements, pulmonary
inflammation, exacerbation of asthma, respiratory-related hospital
admissions, and mortality, are causally associated with ozone exposure.
It also concludes that metabolic effects, including metabolic syndrome
(i.e., changes in insulin or glucose levels, cholesterol levels,
obesity, and blood pressure) and complications due to diabetes are
likely to be causally associated with short-term exposure to ozone. The
evidence is also suggestive of a causal relationship between short-term
exposure to ozone and cardiovascular effects, central nervous system
effects, and total mortality.
For long-term exposure to ozone, the Ozone ISA concludes that
respiratory effects, including new onset asthma, pulmonary
inflammation, and injury, are likely to be causally related with ozone
exposure. The Ozone ISA characterizes the evidence as suggestive of a
causal relationship for associations between long-term ozone exposure
and cardiovascular effects, metabolic effects, reproductive and
developmental effects, central nervous system effects, and total
mortality. The evidence is inadequate to infer a causal relationship
between chronic ozone exposure and increased risk of cancer.
Finally, interindividual variation in human responses to ozone
exposure can result in some groups being at increased risk for
detrimental effects in response to exposure. In addition, some groups
are at increased risk of exposure due to their activities, such as
outdoor workers and children. The Ozone ISA identified several groups
that are at increased risk for ozone-related health effects. These
groups are people with asthma, children and older adults, individuals
with reduced intake of certain nutrients (i.e., Vitamins C and E),
outdoor workers, and individuals having certain genetic variants
related to oxidative metabolism or inflammation. Ozone exposure during
childhood can have lasting effects through adulthood. Such effects
include altered function of the respiratory and immune systems.
Children absorb higher doses (normalized to lung surface area) of
ambient ozone, compared to adults, due to their increased time spent
outdoors, higher ventilation rates relative to body size, and a
tendency to breathe a greater fraction of air through the mouth.
Children also have a higher asthma prevalence compared to adults.
Recent epidemiologic studies provide generally consistent evidence that
long-term ozone exposure is associated with the development of asthma
in children. Studies comparing age groups reported higher magnitude
associations for short-term ozone exposure and respiratory hospital
admissions and emergency room visits among children than among adults.
Panel studies also provide support for experimental studies with
consistent associations between short-term ozone exposure and lung
function and pulmonary inflammation in healthy children. Additional
children's vulnerability and susceptibility factors are listed in
Section XII of this preamble.
2. Particulate Matter
Scientific evidence spanning animal toxicological, controlled human
exposure, and epidemiologic studies shows that exposure to ambient PM
is associated with a broad range of health effects. These health
effects are discussed in detail in the Integrated Science Assessment
for Particulate Matter, which was finalized in December 2019 (PM ISA).
In addition, there is a more targeted evaluation of studies published
since the literature cutoff date of the 2019 p.m. ISA in the Supplement
to the Integrated Science Assessment for PM
(Supplement).102 103 The PM ISA characterizes the causal
nature of relationships between PM exposure and broad health categories
(e.g., cardiovascular effects, respiratory effects, etc.) using a
weight-of-evidence approach.\104\ Within this characterization, the PM
ISA summarizes the health effects evidence for short-term (i.e., hours
up to one month) and long-term (i.e., one month to years) exposures to
PM2.5, PM10-2.5, and
ultrafine particles, and concludes that exposures to ambient
PM2.5 are associated with a number of adverse health
effects. The following discussion highlights the PM ISA's conclusions,
and summarizes additional information from the Supplement where
appropriate, pertaining to the health effects evidence for both short-
and long-term PM exposures. Further discussion of PM-related health
effects can also be found in the 2022 Policy Assessment for the review
of the PM NAAQS.\105\
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\102\ U.S. EPA. Integrated Science Assessment (ISA) for
Particulate Matter (Final Report, 2019). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
\103\ U.S. EPA. Supplement to the 2019 Integrated Science
Assessment for Particulate Matter (Final Report, 2022). U.S.
Environmental Protection Agency, Washington, DC, EPA/635/R-22/028,
2022.
\104\ The causal framework draws upon the assessment and
integration of evidence from across scientific disciplines, spanning
atmospheric chemistry, exposure, dosimetry and health effects
studies (i.e., epidemiologic, controlled human exposure, and animal
toxicological studies), and assess the related uncertainties and
limitations that ultimately influence our understanding of the
evidence. This framework employs a five-level hierarchy that
classifies the overall weight-of-evidence with respect to the causal
nature of relationships between criteria pollutant exposures and
health and welfare effects using the following categorizations:
causal relationship; likely to be causal relationship; suggestive
of, but not sufficient to infer, a causal relationship; inadequate
to infer the presence or absence of a causal relationship; and not
likely to be a causal relationship (U.S. EPA. (2019). Integrated
Science Assessment for Particulate Matter (Final Report). U.S.
Environmental Protection Agency, Washington, DC, EPA/600/R-19/188,
Section P. 3.2.3).
\105\ U.S. EPA. Policy Assessment (PA) for the Reconsideration
of the National Ambient Air Quality Standards for Particulate Matter
(Final Report, 2022). U.S. Environmental Protection Agency,
Washington, DC, EPA-452/R-22-004, 2022.
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EPA has concluded that recent evidence in combination with evidence
evaluated in the 2009 p.m. ISA supports a ``causal relationship''
between both long- and short-term exposures to PM2.5 and
premature mortality and cardiovascular effects and a ``likely to be
causal relationship'' between long- and short-term PM2.5
exposures and respiratory effects.\106\ Additionally, recent
experimental and epidemiologic studies provide evidence supporting a
``likely to be causal relationship'' between long-term PM2.5
exposure and nervous system effects, and long-term PM2.5
exposure and cancer. Because of remaining uncertainties and limitations
in the evidence base, EPA determined a ``suggestive of, but not
sufficient to infer, a causal relationship'' for long-term
PM2.5 exposure and reproductive and developmental effects
(i.e., male/female reproduction and fertility; pregnancy and birth
outcomes), long- and short-term exposures and metabolic effects, and
short-term exposure and nervous system effects.
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\106\ U.S. EPA. (2009). Integrated Science Assessment for
Particulate Matter (Final Report). U.S. Environmental Protection
Agency, Washington, DC, EPA/600/R-08/139F.
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As discussed extensively in the 2019 p.m. ISA and the Supplement,
recent studies continue to support a ``causal relationship'' between
short- and long-term PM2.5 exposures and
mortality.107 108 For short-term PM2.5 exposure,
multi-city studies, in combination with single- and multi-city studies
evaluated in the 2009 p.m. ISA,
[[Page 4318]]
provide evidence of consistent, positive associations across studies
conducted in different geographic locations, populations with different
demographic characteristics, and studies using different exposure
assignment techniques. Additionally, the consistent and coherent
evidence across scientific disciplines for cardiovascular morbidity,
particularly ischemic events and heart failure, and to a lesser degree
for respiratory morbidity, including exacerbations of chronic
obstructive pulmonary disease (COPD) and asthma, provide biological
plausibility for cause-specific mortality and ultimately total
mortality. Recent epidemiologic studies evaluated in the Supplement,
including studies that employed alternative methods for confounder
control, provide additional support to the evidence base that
contributed to the 2019 p.m. ISA conclusion for short-term
PM2.5 exposure and mortality.
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\107\ U.S. EPA. Integrated Science Assessment (ISA) for
Particulate Matter (Final Report, 2019). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
\108\ U.S. EPA. Supplement to the 2019 Integrated Science
Assessment for Particulate Matter (Final Report, 2022). U.S.
Environmental Protection Agency, Washington, DC, EPA/635/R-22/028,
2022.
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The 2019 p.m. ISA concluded a ``causal relationship'' between long-
term PM2.5 exposure and mortality. In addition to reanalyses
and extensions of the American Cancer Society (ACS) and Harvard Six
Cities (HSC) cohorts, multiple new cohort studies conducted in the
United States and Canada consisting of people employed in a specific
job (e.g., teacher, nurse), and that apply different exposure
assignment techniques, provide evidence of positive associations
between long-term PM2.5 exposure and mortality. Biological
plausibility for mortality due to long-term PM2.5 exposure
is provided by the coherence of effects across scientific disciplines
for cardiovascular morbidity, particularly for coronary heart disease,
stroke, and atherosclerosis, and for respiratory morbidity,
particularly for the development of COPD. Additionally, recent studies
provide evidence indicating that as long-term PM2.5
concentrations decrease there is an increase in life expectancy. Recent
cohort studies evaluated in the Supplement, as well as epidemiologic
studies that conducted accountability analyses or employed alternative
methods for confounder controls, support and extend the evidence base
that contributed to the 2019 p.m. ISA conclusion for long-term
PM2.5 exposure and mortality.
A large body of studies examining both short- and long-term
PM2.5 exposure and cardiovascular effects builds on the
evidence base evaluated in the 2009 p.m. ISA. The strongest evidence
for cardiovascular effects in response to short-term PM2.5
exposures is for ischemic heart disease and heart failure. The evidence
for short-term PM2.5 exposure and cardiovascular effects is
coherent across scientific disciplines and supports a continuum of
effects ranging from subtle changes in indicators of cardiovascular
health to serious clinical events, such as increased emergency
department visits and hospital admissions due to cardiovascular disease
and cardiovascular mortality. For long-term PM2.5 exposure,
there is strong and consistent epidemiologic evidence of a relationship
with cardiovascular mortality. This evidence is supported by
epidemiologic and animal toxicological studies demonstrating a range of
cardiovascular effects including coronary heart disease, stroke,
impaired heart function, and subclinical markers (e.g., coronary artery
calcification, atherosclerotic plaque progression), which collectively
provide coherence and biological plausibility. Recent epidemiologic
studies evaluated in the Supplement, as well as studies that conducted
accountability analyses or employed alternative methods for confounder
control, support and extend the evidence base that contributed to the
2019 p.m. ISA conclusion for both short- and long-term PM2.5
exposure and cardiovascular effects.
Studies evaluated in the 2019 p.m. ISA continue to provide evidence
of a ``likely to be causal relationship'' between both short- and long-
term PM2.5 exposure and respiratory effects. Epidemiologic
studies provide consistent evidence of a relationship between short-
term PM2.5 exposure and asthma exacerbation in children and
COPD exacerbation in adults, as indicated by increases in emergency
department visits and hospital admissions, which is supported by animal
toxicological studies indicating worsening allergic airways disease and
subclinical effects related to COPD. Epidemiologic studies also provide
evidence of a relationship between short-term PM2.5 exposure
and respiratory mortality. However, there is inconsistent evidence of
respiratory effects, specifically lung function declines and pulmonary
inflammation, in controlled human exposure studies. With respect to
long term PM2.5 exposure, epidemiologic studies conducted in
the United States and abroad provide evidence of a relationship with
respiratory effects, including consistent changes in lung function and
lung function growth rate, increased asthma incidence, asthma
prevalence, and wheeze in children; acceleration of lung function
decline in adults; and respiratory mortality. The epidemiologic
evidence is supported by animal toxicological studies, which provide
coherence and biological plausibility for a range of effects including
impaired lung development, decrements in lung function growth, and
asthma development.
Since the 2009 p.m. ISA, a growing body of scientific evidence
examined the relationship between long-term PM2.5 exposure
and nervous system effects, resulting for the first time in a causality
determination for this health effects category of a ``likely to be
causal relationship.'' The strongest evidence for effects on the
nervous system come from epidemiologic studies that consistently report
cognitive decrements and reductions in brain volume in adults. The
effects observed in epidemiologic studies in adults are supported by
animal toxicological studies demonstrating effects on the brain of
adult animals including inflammation, morphologic changes, and
neurodegeneration of specific regions of the brain. There is more
limited evidence for neurodevelopmental effects in children, with some
studies reporting positive associations with autism spectrum disorder
and others providing limited evidence of an association with cognitive
function. While there is some evidence from animal toxicological
studies indicating effects on the brain (i.e., inflammatory and
morphological changes) to support a biologically plausible pathway for
neurodevelopmental effects, epidemiologic studies are limited due to
their lack of control for potential confounding by copollutants, the
small number of studies conducted, and uncertainty regarding critical
exposure windows.
Building off the decades of research demonstrating mutagenicity,
DNA damage, and other endpoints related to genotoxicity due to whole PM
exposures, recent experimental and epidemiologic studies focusing
specifically on PM2.5 provide evidence of a relationship
between long-term PM2.5 exposure and cancer. Epidemiologic
studies examining long-term PM2.5 exposure and lung cancer
incidence and mortality provide evidence of generally positive
associations in cohort studies spanning different populations,
locations, and exposure assignment techniques. Additionally, there is
evidence of positive associations with lung cancer incidence and
mortality in analyses limited to never smokers. In addition,
experimental and epidemiologic studies of genotoxicity, epigenetic
effects, carcinogenic potential, and that PM2.5 exhibits
several characteristics of
[[Page 4319]]
carcinogens provide biological plausibility for cancer development.
This collective body of evidence contributed to the conclusion of a
``likely to be causal relationship.''
For the additional health effects categories evaluated for
PM2.5 in the 2019 p.m. ISA, experimental and epidemiologic
studies provide limited and/or inconsistent evidence of a relationship
with PM2.5 exposure. As a result, the 2019 p.m. ISA
concluded that the evidence is ``suggestive of, but not sufficient to
infer a causal relationship'' for short-term PM2.5 exposure
and metabolic effects and nervous system effects, and long-term
PM2.5 exposures and metabolic effects as well as
reproductive and developmental effects.
In addition to evaluating the health effects attributed to short-
and long-term exposure to PM2.5, the 2019 p.m. ISA also
conducted an extensive evaluation as to whether specific components or
sources of PM2.5 are more strongly related with health
effects than PM2.5 mass. An evaluation of those studies
resulted in the 2019 p.m. ISA concluding that ``many PM2.5
components and sources are associated with many health effects, and the
evidence does not indicate that any one source or component is
consistently more strongly related to health effects than
PM2.5 mass.'' \109\
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\109\ U.S. EPA. Integrated Science Assessment (ISA) for
Particulate Matter (Final Report, 2019). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
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For both PM10-2.5 and UFPs, for all health effects
categories evaluated, the 2019 p.m. ISA concluded that the evidence was
``suggestive of, but not sufficient to infer, a causal relationship''
or ``inadequate to determine the presence or absence of a causal
relationship.'' For PM10-2.5, although a Federal Reference
Method (FRM) was instituted in 2011 to measure PM10-2.5
concentrations nationally, the causality determinations reflect that
the same uncertainty identified in the 2009 p.m. ISA persists with
respect to the method used to estimate PM10-2.5
concentrations in epidemiologic studies. Specifically, across
epidemiologic studies, different approaches are used to estimate
PM10-2.5 concentrations (e.g., direct measurement of
PM10-2.5, difference between PM10 and
PM2.5 concentrations), and it remains unclear how well
correlated PM10-2.5 concentrations are both spatially and
temporally across the different methods used.
For UFPs, which have often been defined as particles <0.1 [micro]m,
the uncertainty in the evidence for the health effect categories
evaluated across experimental and epidemiologic studies reflects the
inconsistency in the exposure metric used (i.e., particle number
concentration, surface area concentration, mass concentration) as well
as the size fractions examined. In epidemiologic studies the size
fraction examined can vary depending on the monitor used and exposure
metric, with some studies examining number count over the entire
particle size range, while experimental studies that use a particle
concentrator often examine particles up to 0.3 [micro]m. Additionally,
due to the lack of a monitoring network, there is limited information
on the spatial and temporal variability of UFPs within the United
States, as well as population exposures to UFPs, which adds uncertainty
to epidemiologic study results.
The 2019 p.m. ISA cites extensive evidence indicating that ``both
the general population as well as specific populations and life stages
are at risk for PM2.5-related health effects.'' \110\ For
example, in support of its ``causal'' and ``likely to be causal''
determinations, the ISA cites substantial evidence for (1) PM-related
mortality and cardiovascular effects in older adults; (2) PM-related
cardiovascular effects in people with pre-existing cardiovascular
disease; (3) PM-related respiratory effects in people with pre-existing
respiratory disease, particularly asthma exacerbations in children; and
(4) PM-related impairments in lung function growth and asthma
development in children. The ISA additionally notes that stratified
analyses (i.e., analyses that directly compare PM-related health
effects across groups) provide strong evidence for racial and ethnic
differences in PM2.5 exposures and in the risk of
PM2.5-related health effects, specifically within Hispanic
and non-Hispanic Black populations, with some evidence of increased
risk for populations of low socioeconomic status. Recent studies
evaluated in the Supplement support the conclusion of the 2019 p.m. ISA
with respect to disparities in both PM2.5 exposure and
health risk by race and ethnicity and provide additional support for
disparities for populations of lower socioeconomic status.\111\
Additionally, evidence spanning epidemiologic studies that conducted
stratified analyses, experimental studies focusing on animal models of
disease or individuals with pre-existing disease, dosimetry studies, as
well as studies focusing on differential exposure suggest that
populations with pre-existing cardiovascular or respiratory disease,
populations that are overweight or obese, populations that have
particular genetic variants, and current/former smokers could be at
increased risk for adverse PM2.5-related health effects. The
2022 Policy Assessment for the review of the PM NAAQS also highlights
that factors that may contribute to increased risk of PM2.5-
related health effects include lifestage (children and older adults),
pre-existing diseases (cardiovascular disease and respiratory disease),
race/ethnicity, and socioeconomic status.\112\
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\110\ U.S. EPA. Integrated Science Assessment (ISA) for
Particulate Matter (Final Report, 2019). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
\111\ U.S. EPA. Supplement to the 2019 Integrated Science
Assessment for Particulate Matter (Final Report, 2022). U.S.
Environmental Protection Agency, Washington, DC, EPA/635/R-22/028,
2022.
\112\ U.S. EPA. Policy Assessment (PA) for the Reconsideration
of the National Ambient Air Quality Standards for Particulate Matter
(Final Report, 2022). U.S. Environmental Protection Agency,
Washington, DC, EPA-452/R-22-004, 2022, p. 3-53.
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3. Nitrogen Oxides
The most recent review of the health effects of oxides of nitrogen
completed by EPA can be found in the 2016 Integrated Science Assessment
for Oxides of Nitrogen--Health Criteria (ISA for Oxides of
Nitrogen).\113\ The primary source of NO2 is motor vehicle
emissions, and ambient NO2 concentrations tend to be highly
correlated with other traffic-related pollutants. Thus, a key issue in
characterizing the causality of NO2-health effect
relationships consists of evaluating the extent to which studies
supported an effect of NO2 that is independent of other
traffic-related pollutants. EPA concluded that the findings for asthma
exacerbation integrated from epidemiologic and controlled human
exposure studies provided evidence that is sufficient to infer a causal
relationship between respiratory effects and short-term NO2
exposure. The strongest evidence supporting an independent effect of
NO2 exposure comes from controlled human exposure studies
demonstrating increased airway responsiveness in individuals with
asthma following ambient-relevant NO2 exposures. The
coherence of this evidence with epidemiologic findings for asthma
hospital admissions and emergency department visits as well as lung
function decrements and increased pulmonary inflammation in children
with asthma describe a plausible pathway by which NO2
exposure can
[[Page 4320]]
cause an asthma exacerbation. The 2016 ISA for Oxides of Nitrogen also
concluded that there is likely to be a causal relationship between
long-term NO2 exposure and respiratory effects. This
conclusion is based on new epidemiologic evidence for associations of
NO2 with asthma development in children combined with
biological plausibility from experimental studies.
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\113\ U.S. EPA. Integrated Science Assessment for Oxides of
Nitrogen--Health Criteria (2016 Final Report). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-15/068, 2016.
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In evaluating a broader range of health effects, the 2016 ISA for
Oxides of Nitrogen concluded that evidence is ``suggestive of, but not
sufficient to infer, a causal relationship'' between short-term
NO2 exposure and cardiovascular effects and mortality and
between long-term NO2 exposure and cardiovascular effects
and diabetes, birth outcomes, and cancer. In addition, the scientific
evidence is inadequate (insufficient consistency of epidemiologic and
toxicological evidence) to infer a causal relationship for long-term
NO2 exposure with fertility, reproduction, and pregnancy, as
well as with postnatal development. A key uncertainty in understanding
the relationship between these non-respiratory health effects and
short- or long-term exposure to NO2 is copollutant
confounding, particularly by other roadway pollutants. The available
evidence for non-respiratory health effects does not adequately address
whether NO2 has an independent effect or whether it
primarily represents effects related to other or a mixture of traffic-
related pollutants.
The 2016 ISA for Oxides of Nitrogen concluded that people with
asthma, children, and older adults are at increased risk for
NO2-related health effects. In these groups and lifestages,
NO2 is consistently related to larger effects on outcomes
related to asthma exacerbation, for which there is confidence in the
relationship with NO2 exposure.
4. Carbon Monoxide
Information on the health effects of CO can be found in the January
2010 Integrated Science Assessment for Carbon Monoxide (CO ISA).\114\
The CO ISA presents conclusions regarding the presence of causal
relationships between CO exposure and categories of adverse health
effects.\115\ This section provides a summary of the health effects
associated with exposure to ambient concentrations of CO, along with
the CO ISA conclusions.\116\
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\114\ U.S. EPA, (2010). Integrated Science Assessment for Carbon
Monoxide (Final Report). U.S. Environmental Protection Agency,
Washington, DC, EPA/600/R-09/019F, 2010. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=218686.
\115\ The ISA evaluates the health evidence associated with
different health effects, assigning one of five ``weight of
evidence'' determinations: causal relationship, likely to be a
causal relationship, suggestive of a causal relationship, inadequate
to infer a causal relationship, and not likely to be a causal
relationship. For definitions of these levels of evidence, please
refer to Section 1.6 of the ISA.
\116\ Personal exposure includes contributions from many
sources, and in many different environments. Total personal exposure
to CO includes both ambient and non-ambient components; and both
components may contribute to adverse health effects.
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Controlled human exposure studies of subjects with coronary artery
disease show a decrease in the time to onset of exercise-induced angina
(chest pain) and electrocardiogram changes following CO exposure. In
addition, epidemiologic studies observed associations between short-
term CO exposure and cardiovascular morbidity, particularly increased
emergency room visits and hospital admissions for coronary heart
disease (including ischemic heart disease, myocardial infarction, and
angina). Some epidemiologic evidence is also available for increased
hospital admissions and emergency room visits for congestive heart
failure and cardiovascular disease as a whole. The CO ISA concludes
that a causal relationship is likely to exist between short-term
exposures to CO and cardiovascular morbidity. It also concludes that
available data are inadequate to conclude that a causal relationship
exists between long-term exposures to CO and cardiovascular morbidity.
Animal studies show various neurological effects with in-utero CO
exposure. Controlled human exposure studies report central nervous
system and behavioral effects following low-level CO exposures,
although the findings have not been consistent across all studies. The
CO ISA concludes that the evidence is suggestive of a causal
relationship with both short- and long-term exposure to CO and central
nervous system effects.
A number of studies cited in the CO ISA have evaluated the role of
CO exposure in birth outcomes such as preterm birth or cardiac birth
defects. There is limited epidemiologic evidence of a CO-induced effect
on preterm births and birth defects, with weak evidence for a decrease
in birth weight. Animal toxicological studies have found perinatal CO
exposure to affect birth weight, as well as other developmental
outcomes. The CO ISA concludes that the evidence is suggestive of a
causal relationship between long-term exposures to CO and developmental
effects and birth outcomes.
Epidemiologic studies provide evidence of associations between
short-term CO concentrations and respiratory morbidity such as changes
in pulmonary function, respiratory symptoms, and hospital admissions. A
limited number of epidemiologic studies considered copollutants such as
ozone, SO2, and PM in two-pollutant models and found that CO
risk estimates were generally robust, although this limited evidence
makes it difficult to disentangle effects attributed to CO itself from
those of the larger complex air pollution mixture. Controlled human
exposure studies have not extensively evaluated the effect of CO on
respiratory morbidity. Animal studies at levels of 50-100 ppm CO show
preliminary evidence of altered pulmonary vascular remodeling and
oxidative injury. The CO ISA concludes that the evidence is suggestive
of a causal relationship between short-term CO exposure and respiratory
morbidity, and inadequate to conclude that a causal relationship exists
between long-term exposure and respiratory morbidity.
Finally, the CO ISA concludes that the epidemiologic evidence is
suggestive of a causal relationship between short-term concentrations
of CO and mortality. Epidemiologic evidence suggests an association
exists between short-term exposure to CO and mortality, but limited
evidence is available to evaluate cause-specific mortality outcomes
associated with CO exposure. In addition, the attenuation of CO risk
estimates that was often observed in copollutant models contributes to
the uncertainty as to whether CO is acting alone or as an indicator for
other combustion-related pollutants. The CO ISA also concludes that
there is not likely to be a causal relationship between relevant long-
term exposures to CO and mortality.
5. Diesel Exhaust
In EPA's 2002 Diesel Health Assessment Document (Diesel HAD),
exposure to diesel exhaust was classified as likely to be carcinogenic
to humans by inhalation from environmental exposures, in accordance
with the revised draft 1996/1999 EPA cancer
guidelines.117 118 A number of
[[Page 4321]]
other agencies (National Institute for Occupational Safety and Health,
the International Agency for Research on Cancer, the World Health
Organization, California EPA, and the U.S. Department of Health and
Human Services) made similar hazard classifications prior to 2002. EPA
also concluded in the 2002 Diesel HAD that it was not possible to
calculate a cancer unit risk for diesel exhaust due to limitations in
the exposure data for the occupational groups or the absence of a dose-
response relationship.
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\117\ U.S. EPA. (1999). Guidelines for Carcinogen Risk
Assessment. Review Draft. NCEA-F-0644, July. Washington, DC: U.S.
EPA. Retrieved on March 19, 2009 from http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=54932.
\118\ U.S. EPA (2002). Health Assessment Document for Diesel
Engine Exhaust. EPA/600/8-90/057F Office of research and
Development, Washington, DC. Retrieved on March 17, 2009 from http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060. pp. 1-1 1-2.
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In the absence of a cancer unit risk, the Diesel HAD sought to
provide additional insight into the significance of the diesel exhaust
cancer hazard by estimating possible ranges of risk that might be
present in the population. An exploratory analysis was used to
characterize a range of possible lung cancer risk. The outcome was that
environmental risks of cancer from long-term diesel exhaust exposures
could plausibly range from as low as 10-5 to as
high as 10-3. Because of uncertainties, the
analysis acknowledged that the risks could be lower than
10-5, and a zero risk from diesel exhaust
exposure could not be ruled out.
Noncancer health effects of acute and chronic exposure to diesel
exhaust emissions are also of concern to EPA. EPA derived a diesel
exhaust reference concentration (RfC) from consideration of four well-
conducted chronic rat inhalation studies showing adverse pulmonary
effects. The RfC is 5 [micro]g/m3 for diesel exhaust
measured as diesel particulate matter. This RfC does not consider
allergenic effects such as those associated with asthma or immunologic
or the potential for cardiac effects. There was emerging evidence in
2002, discussed in the Diesel HAD, that exposure to diesel exhaust can
exacerbate these effects, but the exposure-response data were lacking
at that time to derive an RfC based on these then-emerging
considerations. The Diesel HAD states, ``With [diesel particulate
matter] being a ubiquitous component of ambient PM, there is an
uncertainty about the adequacy of the existing [diesel exhaust]
noncancer database to identify all the pertinent [diesel exhaust]-
caused noncancer health hazards.'' The Diesel HAD also notes ``that
acute exposure to [diesel exhaust] has been associated with irritation
of the eye, nose, and throat, respiratory symptoms (cough and phlegm),
and neurophysiological symptoms such as headache, lightheadedness,
nausea, vomiting, and numbness or tingling of the extremities.'' The
Diesel HAD notes that the cancer and noncancer hazard conclusions
applied to the general use of diesel engines then on the market and as
cleaner engines replace a substantial number of existing ones, the
applicability of the conclusions would need to be reevaluated.
It is important to note that the Diesel HAD also briefly summarizes
health effects associated with ambient PM and discusses EPA's then-
annual PM2.5 NAAQS of 15 [micro]g/m3.\119\ There
is a large and extensive body of human data showing a wide spectrum of
adverse health effects associated with exposure to ambient PM, of which
diesel exhaust is an important component. The PM2.5 NAAQS is
designed to provide protection from the noncancer health effects and
premature mortality attributed to exposure to PM2.5. The
contribution of diesel PM to total ambient PM varies in different
regions of the country and also, within a region, from one area to
another. The contribution can be high in near-roadway environments, for
example, or in other locations where diesel engine use is concentrated.
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\119\ See Section II.A.2 for discussion of the current
PM2.5 NAAQS standard.
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Since 2002, several new studies have been published which continue
to report increased lung cancer risk associated with occupational
exposure to diesel exhaust from older engines. Of particular note since
2011 are three new epidemiology studies that have examined lung cancer
in occupational populations, for example, truck drivers, underground
nonmetal miners, and other diesel motor-related occupations. These
studies reported increased risk of lung cancer with exposure to diesel
exhaust with evidence of positive exposure-response relationships to
varying degrees.120 121 122 These newer studies (along with
others that have appeared in the scientific literature) add to the
evidence EPA evaluated in the 2002 Diesel HAD and further reinforce the
concern that diesel exhaust exposure likely poses a lung cancer hazard.
The findings from these newer studies do not necessarily apply to newer
technology diesel engines (i.e., heavy-duty highway engines from 2007
and later model years) since the newer engines have large reductions in
the emission constituents compared to older technology diesel engines.
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\120\ Garshick, Eric, Francine Laden, Jaime E. Hart, Mary E.
Davis, Ellen A. Eisen, and Thomas J. Smith. 2012. Lung cancer and
elemental carbon exposure in trucking industry workers.
Environmental Health Perspectives 120(9): 1301-1306.
\121\ Silverman, D.T., Samanic, C.M., Lubin, J.H., Blair, A.E.,
Stewart, P.A., Vermeulen, R., & Attfield, M.D. (2012). The diesel
exhaust in miners study: a nested case-control study of lung cancer
and diesel exhaust. Journal of the National Cancer Institute.
\122\ Olsson, Ann C., et al. ``Exposure to diesel motor exhaust
and lung cancer risk in a pooled analysis from case-control studies
in Europe and Canada.'' American Journal of Respiratory and Critical
Care Medicine 183.7 (2011): 941-948.
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In light of the growing body of scientific literature evaluating
the health effects of exposure to diesel exhaust, in June 2012 the
World Health Organization's International Agency for Research on Cancer
(IARC), a recognized international authority on the carcinogenic
potential of chemicals and other agents, evaluated the full range of
cancer-related health effects data for diesel engine exhaust. IARC
concluded that diesel exhaust should be regarded as ``carcinogenic to
humans.'' \123\ This designation was an update from its 1988 evaluation
that considered the evidence to be indicative of a ``probable human
carcinogen.''
---------------------------------------------------------------------------
\123\ IARC [International Agency for Research on Cancer].
(2013). Diesel and gasoline engine exhausts and some nitroarenes.
IARC Monographs Volume 105. [Online at http://monographs.iarc.fr/ENG/Monographs/vol105/index.php].
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6. Air Toxics
Heavy-duty engine emissions contribute to ambient levels of air
toxics that are known or suspected human or animal carcinogens, or that
have noncancer health effects. These compounds include, but are not
limited to, benzene, formaldehyde, acetaldehyde, and naphthalene. These
compounds were identified as national or regional cancer risk drivers
or contributors in the 2018 AirToxScreen Assessment and have
significant inventory contributions from mobile
sources.124 125 Chapter 4 of the RIA includes additional
information on the health effects associated with exposure to each of
these pollutants.
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\124\ U.S. EPA (2022) Technical Support Document EPA Air Toxics
Screening Assessment. 2017AirToxScreen TSD. https://www.epa.gov/system/files/documents/2022-03/airtoxscreen_2017tsd.pdf.
\125\ U.S. EPA (2022) 2018 AirToxScreen Risk Drivers. https://www.epa.gov/AirToxScreen/airtoxscreen-risk-drivers.
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7. Exposure and Health Effects Associated With Traffic
Locations in close proximity to major roadways generally have
elevated concentrations of many air pollutants emitted from motor
vehicles. Hundreds of studies have been published in peer-reviewed
journals, concluding that concentrations of CO, CO2, NO,
NO2, benzene, aldehydes, PM, black carbon, and many other
compounds are elevated in ambient air within approximately
[[Page 4322]]
300-600 meters (about 1,000-2,000 feet) of major roadways. The highest
concentrations of most pollutants emitted directly by motor vehicles
are found at locations within 50 meters (about 165 feet) of the edge of
a roadway's traffic lanes.
A large-scale review of air quality measurements in the vicinity of
major roadways between 1978 and 2008 concluded that the pollutants with
the steepest concentration gradients in vicinities of roadways were CO,
UFPs, metals, elemental carbon (EC), NO, NOX, and several
VOCs.\126\ These pollutants showed a large reduction in concentrations
within 100 meters downwind of the roadway. Pollutants that showed more
gradual reductions with distance from roadways included benzene,
NO2, PM2.5, and PM10. In reviewing the
literature, Karner et al., (2010) reported that results varied based on
the method of statistical analysis used to determine the gradient in
pollutant concentration. More recent studies continue to show
significant concentration gradients of traffic-related air pollution
around major
roads.127 128 129 130 131 132 133 134 135 136
There is evidence that EPA's regulations for vehicles have lowered the
near-road concentrations and gradients.\137\ Starting in 2010, EPA
required through the NAAQS process that air quality monitors be placed
near high-traffic roadways for determining concentrations of CO,
NO2, and PM2.5 (in addition to those existing
monitors located in neighborhoods and other locations farther away from
pollution sources). The monitoring data for NO2 indicate
that in urban areas, monitors near roadways often report the highest
concentrations of NO2.\138\ More recent studies of traffic-
related air pollutants continue to report sharp gradients around
roadways, particularly within several hundred meters.139 140
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\126\ Karner, A.A.; Eisinger, D.S.; Niemeier, D.A. (2010). Near-
roadway air quality: synthesizing the findings from real-world data.
Environ Sci Technol 44: 5334-5344.
\127\ McDonald, B.C.; McBride, Z.C.; Martin, E.W.; Harley, R.A.
(2014) High-resolution mapping of motor vehicle carbon dioxide
emissions. J. Geophys. Res. Atmos.,119, 5283-5298, doi:10.1002/
2013JD021219.
\128\ Kimbrough, S.; Baldauf, R.W.; Hagler, G.S.W.; Shores,
R.C.; Mitchell, W.; Whitaker, D.A.; Croghan, C.W.; Vallero, D.A.
(2013) Long-term continuous measurement of near-road air pollution
in Las Vegas: seasonal variability in traffic emissions impact on
air quality. Air Qual Atmos Health 6: 295-305. DOI 10.1007/s11869-
012-0171-x.
\129\ Kimbrough, S.; Palma, T.; Baldauf, R.W. (2014) Analysis of
mobile source air toxics (MSATs)--Near-road VOC and carbonyl
concentrations. Journal of the Air & Waste Management Association,
64:3, 349-359, DOI: 10.1080/10962247.2013.863814.
\130\ Kimbrough, S.; Owen, R.C.; Snyder, M.; Richmond-Bryant, J.
(2017) NO to NO2 Conversion Rate Analysis and
Implications for Dispersion Model Chemistry Methods using Las Vegas,
Nevada Near-Road Field Measurements. Atmos Environ 165: 23-24.
\131\ Hilker, N.; Wang, J.W.; Jong, C-H.; Healy, R.M.; Sofowote,
U.; Debosz, J.; Su, Y.; Noble, M.; Munoz, A.; Doerkson, G.; White,
L.; Audette, C.; Herod, D.; Brook, J.R.; Evans, G.J. (2019) Traffic-
related air pollution near roadways: discerning local impacts from
background. Atmos. Meas. Tech., 12, 5247-5261. https://doi.org/10.5194/amt-12-5247-2019.
\132\ Grivas, G.; Stavroulas, I.; Liakakou, E.; Kaskaoutis,
D.G.; Bougiatioti, A.; Paraskevopoulou, D.; Gerasopoulos, E.;
Mihalopoulos, N. (2019) Measuring the spatial variability of black
carbon in Athens during wintertime. Air Quality, Atmosphere & Health
(2019) 12:1405-1417. https://doi.org/10.1007/s11869-019-00756-y.
\133\ Apte, J.S.; Messier, K.P.; Gani, S.; Brauer, M.;
Kirchstetter, T.W.; Lunden, M.M.; Marshall, J.D.; Portier, C.J.;
Vermeulen, R.C.H.; Hamburg, S.P. (2017) High-Resolution Air
Pollution Mapping with Google Street View Cars: Exploiting Big Data.
Environ Sci Technol 51: 6999-7008. https://doi.org/10.1021/acs.est.7b00891.
\134\ Dabek-Zlotorzynska, E.; Celo, V.; Ding, L.; Herod, D.;
Jeong, C-H.; Evans, G.; Hilker, N. (2019) Characteristics and
sources of PM2.5 and reactive gases near roadways in two
metropolitan areas in Canada. Atmos Environ 218: 116980. https://doi.org/10.1016/j.atmosenv.2019.116980.
\135\ Apte, J.S.; Messier, K.R.; Gani, S.; et al. (2017) High-
resolution air pollution mapping with Google Street View cars:
exploiting big data. Environ Sci Technol 51: 6999-7018, [Online at
https://doi.org/10.1021/acs.est.7b00891].
\136\ Gu, P.; Li, H.Z.; Ye, Q.; et al. (2018) Intercity
variability of particulate matter is driven by carbonaceous sources
and correlated with land-use variables. Environ Sci Technol 52: 52:
11545-11554. [Online at http://dx.doi.org/10.1021/acs.est.8b03833].
\137\ Sarnat, J.A.; Russell, A.; Liang, D.; Moutinho, J.L.;
Golan, R.; Weber, R.; Gao, D.; Sarnat, S.; Chang, H.H.; Greenwald,
R.; Yu, T. (2018) Developing Multipollutant Exposure Indicators of
Traffic Pollution: The Dorm Room Inhalation to Vehicle Emissions
(DRIVE) Study. Health Effects Institute Research Report Number 196.
[Online at: https://www.healtheffects.org/publication/developing-multipollutant-exposure-indicators-traffic-pollution-dorm-room-inhalation].
\138\ Gantt, B; Owen, R.C.; Watkins, N. (2021) Characterizing
nitrogen oxides and fine particulate matter near major highways in
the United States using the National Near-road Monitoring Network.
Environ Sci Technol 55: 2831-2838. [Online at https://doi.org/10.1021/acs.est.0c05851].
\139\ Apte, J.S.; Messier, K.R.; Gani, S.; et al. (2017) High-
resolution air pollution mapping with Google Street View cars:
exploiting big data. Environ Sci Technol 51: 6999-7018, [Online at
https://doi.org/10.1021/acs.est.7b00891].
\140\ Gu, P.; Li, H.Z.; Ye, Q.; et al. (2018) Intercity
variability of particulate matter is driven by carbonaceous sources
and correlated with land-use variables. Environ Sci Technol 52: 52:
11545-11554. [Online at http://dx.doi.org/10.1021/acs.est.8b03833].
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For pollutants with relatively high background concentrations
relative to near-road concentrations, detecting concentration gradients
can be difficult. For example, many carbonyls have high background
concentrations as a result of photochemical breakdown of precursors
from many different organic compounds. However, several studies have
measured carbonyls in multiple weather conditions and found higher
concentrations of many carbonyls downwind of
roadways.141 142 These findings suggest a substantial
roadway source of these carbonyls.
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\141\ Liu, W.; Zhang, J.; Kwon, J.l.; et l. (2006).
Concentrations and source characteristics of airborne carbonyl
compounds measured outside urban residences. J Air Waste Manage
Assoc 56: 1196-1204.
\142\ Cahill, T.M.; Charles, M.J.; Seaman, V.Y. (2010).
Development and application of a sensitive method to determine
concentrations of acrolein and other carbonyls in ambient air.
Health Effects Institute Research Report 149. Available at https://www.healtheffects.org/system/files/Cahill149.pdf.
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In the past 30 years, many studies have been published with results
reporting that populations who live, work, or go to school near high-
traffic roadways experience higher rates of numerous adverse health
effects, compared to populations far away from major roads.\143\ In
addition, numerous studies have found adverse health effects associated
with spending time in traffic, such as commuting or walking along high-
traffic roadways, including studies among
children.144 145 146 147 The health outcomes with the
strongest evidence linking them with traffic-associated air pollutants
are respiratory effects, particularly in asthmatic children, and
cardiovascular effects. Commenters on the NPRM stressed the importance
of consideration of the impacts of traffic-related air pollution,
especially NOX, on children's health.
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\143\ In the widely-used PubMed database of health publications,
between January 1, 1990 and December 31, 2021, 1,979 publications
contained the keywords ``traffic, pollution, epidemiology,'' with
approximately half the studies published after 2015.
\144\ Laden, F.; Hart, J.E.; Smith, T.J.; Davis, M.E.; Garshick,
E. (2007) Cause-specific mortality in the unionized U.S. trucking
industry. Environmental Health Perspect 115:1192-1196.
\145\ Peters, A.; von Klot, S.; Heier, M.; Trentinaglia, I.;
H[ouml]rmann, A.; Wichmann, H.E.; L[ouml]wel, H. (2004) Exposure to
traffic and the onset of myocardial infarction. New England J Med
351: 1721-1730.
\146\ Zanobetti, A.; Stone, P.H.; Spelzer, F.E.; Schwartz, J.D.;
Coull, B.A.; Suh, H.H.; Nearling, B.D.; Mittleman, M.A.; Verrier,
R.L.; Gold, D.R. (2009) T-wave alternans, air pollution and traffic
in high-risk subjects. Am J Cardiol 104: 665-670.
\147\ Adar, S.; Adamkiewicz, G.; Gold, D.R.; Schwartz, J.;
Coull, B.A.; Suh, H. (2007) Ambient and microenvironmental particles
and exhaled nitric oxide before and after a group bus trip. Environ
Health Perspect 115: 507-512.
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Numerous reviews of this body of health literature have been
published. In a 2022 final report, an expert panel of the Health
Effects Institute (HEI) employed a systematic review focusing on
selected health endpoints related to exposure to traffic-related air
pollution.\148\ The HEI panel concluded
[[Page 4323]]
that there was a high level of confidence in evidence between long-term
exposure to traffic-related air pollution and health effects in adults,
including all-cause, circulatory, and ischemic heart disease
mortality.\149\ The panel also found that there is a moderate-to-high
level of confidence in evidence of associations with asthma onset and
acute respiratory infections in children and lung cancer and asthma
onset in adults. This report follows on an earlier expert review
published by HEI in 2010, where it found strongest evidence for asthma-
related traffic impacts. Other literature reviews have been published
with conclusions generally similar to the HEI
panels'.150 151 152 153 Additionally, in 2014, researchers
from the U.S. Centers for Disease Control and Prevention (CDC)
published a systematic review and meta-analysis of studies evaluating
the risk of childhood leukemia associated with traffic exposure and
reported positive associations between ``postnatal'' proximity to
traffic and leukemia risks, but no such association for ``prenatal''
exposures.\154\ The U.S. Department of Health and Human Services'
National Toxicology Program (NTP) published a monograph including a
systematic review of traffic-related air pollution and its impacts on
hypertensive disorders of pregnancy. The NTP concluded that exposure to
traffic-related air pollution is ``presumed to be a hazard to pregnant
women'' for developing hypertensive disorders of pregnancy.\155\
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\148\ HEI Panel on the Health Effects of Long-Term Exposure to
Traffic-Related Air Pollution (2022) Systematic review and meta-
analysis of selected health effects of long-term exposure to
traffic-related air pollution. Health Effects Institute Special
Report 23. [Online at https://www.healtheffects.org/system/files/hei-special-report-23_1.pdf.] This more recent review focused on
health outcomes related to birth effects, respiratory effects,
cardiometabolic effects, and mortality.
\149\ Boogaard, H.; Patton. A.P.; Atkinson, R.W.; Brook, J.R.;
Chang, H.H.; Crouse, D.L.; Fussell, J.C.; Hoek, G.; Hoffman, B.;
Kappeler, R.; Kutlar Joss, M.; Ondras, M.; Sagiv, S.K.; Somoli, E.;
Shaikh, R.; Szpiro, A.A.; Van Vliet E.D.S.; Vinneau, D.; Weuve, J.;
Lurmann, F.W.; Forastiere, F. (2022) Long-term exposure to traffic-
related air pollution and selected health outcomes: a systematic
review and meta-analysis. Environ Intl 164: 107262. [Online at
https://doi.org/10.1016/j.envint.2022.107262].
\150\ Boothe, V.L.; Shendell, D.G. (2008). Potential health
effects associated with residential proximity to freeways and
primary roads: review of scientific literature, 1999-2006. J Environ
Health 70: 33-41.
\151\ Salam, M.T.; Islam, T.; Gilliland, F.D. (2008). Recent
evidence for adverse effects of residential proximity to traffic
sources on asthma. Curr Opin Pulm Med 14: 3-8.
\152\ Sun, X.; Zhang, S.; Ma, X. (2014) No association between
traffic density and risk of childhood leukemia: a meta-analysis.
Asia Pac J Cancer Prev 15: 5229-5232.
\153\ Raaschou-Nielsen, O.; Reynolds, P. (2006). Air pollution
and childhood cancer: a review of the epidemiological literature.
Int J Cancer 118: 2920-9.
\154\ Boothe, V.L.; Boehmer, T.K.; Wendel, A.M.; Yip, F.Y.
(2014) Residential traffic exposure and childhood leukemia: a
systematic review and meta-analysis. Am J Prev Med 46: 413-422.
\155\ National Toxicology Program (2019) NTP Monograph on the
Systematic Review of Traffic-related Air Pollution and Hypertensive
Disorders of Pregnancy. NTP Monograph 7. https://ntp.niehs.nih.gov/ntp/ohat/trap/mgraph/trap_final_508.pdf.
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Health outcomes with few publications suggest the possibility of
other effects still lacking sufficient evidence to draw definitive
conclusions. Among these outcomes with a small number of positive
studies are neurological impacts (e.g., autism and reduced cognitive
function) and reproductive outcomes (e.g., preterm birth, low birth
weight).156 157 158 159 160
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\156\ Volk, H.E.; Hertz-Picciotto, I.; Delwiche, L.; et al.
(2011). Residential proximity to freeways and autism in the CHARGE
study. Environ Health Perspect 119: 873-877.
\157\ Franco-Suglia, S.; Gryparis, A.; Wright, R.O.; et al.
(2007). Association of black carbon with cognition among children in
a prospective birth cohort study. Am J Epidemiol. doi: 10.1093/aje/
kwm308. [Online at http://dx.doi.org].
\158\ Power, M.C.; Weisskopf, M.G.; Alexeef, S.E.; et al.
(2011). Traffic-related air pollution and cognitive function in a
cohort of older men. Environ Health Perspect 2011: 682-687.
\159\ Wu, J.; Wilhelm, M.; Chung, J.; et al. (2011). Comparing
exposure assessment methods for traffic-related air pollution in and
adverse pregnancy outcome study. Environ Res 111: 685-6692.
\160\ Stenson, C.; Wheeler, A.J.; Carver, A.; et al. (2021) The
impact of traffic-related air pollution on child and adolescent
academic performance: a systematic review. Environ Intl 155: 106696
[Online at https://doi.org/10.1016/j.envint.2021.106696].
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In addition to health outcomes, particularly cardiopulmonary
effects, conclusions of numerous studies suggest mechanisms by which
traffic-related air pollution affects health. For example, numerous
studies indicate that near-roadway exposures may increase systemic
inflammation, affecting organ systems, including blood vessels and
lungs.161 162 163 164 Additionally, long-term exposures in
near-road environments have been associated with inflammation-
associated conditions, such as atherosclerosis and
asthma.165 166 167
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\161\ Riediker, M. (2007). Cardiovascular effects of fine
particulate matter components in highway patrol officers. Inhal
Toxicol 19: 99-105. doi: 10.1080/08958370701495238.
\162\ Alexeef, S.E.; Coull, B.A.; Gryparis, A.; et al. (2011).
Medium-term exposure to traffic-related air pollution and markers of
inflammation and endothelial function. Environ Health Perspect 119:
481-486. doi:10.1289/ehp.1002560.
\163\ Eckel. S.P.; Berhane, K.; Salam, M.T.; et al. (2011).
Residential Traffic-related pollution exposure and exhaled nitric
oxide in the Children's Health Study. Environ Health Perspect.
doi:10.1289/ehp.1103516.
\164\ Zhang, J.; McCreanor, J.E.; Cullinan, P.; et al. (2009).
Health effects of real-world exposure diesel exhaust in persons with
asthma. Res Rep Health Effects Inst 138. [Online at http://www.healtheffects.org].
\165\ Adar, S.D.; Klein, R.; Klein, E.K.; et al. (2010). Air
pollution and the microvasculature: a cross-sectional assessment of
in vivo retinal images in the population-based Multi-Ethnic Study of
Atherosclerosis. PLoS Med 7(11): E1000372. doi:10.1371/
journal.pmed.1000372. Available at http://dx.doi.org.
\166\ Kan, H.; Heiss, G.; Rose, K.M.; et al. (2008). Prospective
analysis of traffic exposure as a risk factor for incident coronary
heart disease: The Atherosclerosis Risk in Communities (ARIC) study.
Environ Health Perspect 116: 1463-1468. doi:10.1289/ehp.11290.
Available at http://dx.doi.org.
\167\ McConnell, R.; Islam, T.; Shankardass, K.; et al. (2010).
Childhood incident asthma and traffic-related air pollution at home
and school. Environ Health Perspect 1021-1026.
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Several studies suggest that some factors may increase
susceptibility to the effects of traffic-associated air pollution.
Several studies have found stronger adverse health associations in
children experiencing chronic social stress, such as in violent
neighborhoods or in homes with low incomes or high family
stress.168 169 170 171
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\168\ Islam, T.; Urban, R.; Gauderman, W.J.; et al. (2011).
Parental stress increases the detrimental effect of traffic exposure
on children's lung function. Am J Respir Crit Care Med.
\169\ Clougherty, J.E.; Levy, J.I.; Kubzansky, L.D.; et al.
(2007). Synergistic effects of traffic-related air pollution and
exposure to violence on urban asthma etiology. Environ Health
Perspect 115: 1140-1146.
\170\ Chen, E.; Schrier, H.M.; Strunk, R.C.; et al. (2008).
Chronic traffic-related air pollution and stress interact to predict
biologic and clinical outcomes in asthma. Environ Health Perspect
116: 970-5.
\171\ Long, D.; Lewis, D.; Langpap, C. (2021) Negative traffic
externalities and infant health: the role of income heterogeneity
and residential sorting. Environ and Resource Econ 80: 637-674.
[Online at https://doi.org/10.1007/s10640-021-00601-w].
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The risks associated with residence, workplace, or schools near
major roads are of potentially high public health significance due to
the large population in such locations. The 2013 U.S. Census Bureau's
American Housing Survey (AHS) was the last AHS that included whether
housing units were within 300 feet of an ``airport, railroad, or
highway with four or more lanes.'' \172\ The 2013 survey reports that
17.3 million housing units, or 13 percent of all housing units in the
United States, were in such areas. Assuming that populations and
housing units are in the same locations, this corresponds to a
population of more than 41 million U.S. residents in close proximity to
high-traffic roadways or other transportation sources. According to the
Central Intelligence Agency's World Factbook, based on data collected
between 2012-2014, the United States had 6,586,610 km of roadways,
293,564 km of railways, and 13,513 airports. As such, highways
represent the overwhelming majority of transportation facilities
described by this factor in the AHS.
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\172\ The variable was known as ``ETRANS'' in the questions
about the neighborhood.
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[[Page 4324]]
EPA also conducted a study to estimate the number of people living
near truck freight routes in the United States.\173\ Based on a
population analysis using the U.S. Department of Transportation's
(USDOT) Freight Analysis Framework 4 (FAF4) and population data from
the 2010 decennial census, an estimated 72 million people live within
200 meters of these freight routes.174 175 In addition,
relative to the rest of the population, people of color and those with
lower incomes are more likely to live near FAF4 truck routes. They are
also more likely to live in metropolitan areas. The EPA's Exposure
Factor Handbook also indicates that, on average, Americans spend more
than an hour traveling each day, bringing nearly all residents into a
high-exposure microenvironment for part of the day.\176\
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\173\ U.S. EPA (2021). Estimation of Population Size and
Demographic Characteristics among People Living Near Truck Routes in
the Conterminous United States. Memorandum to the Docket.
\174\ FAF4 is a model from the USDOT's Bureau of Transportation
Statistics (BTS) and Federal Highway Administration (FHWA), which
provides data associated with freight movement in the U.S. It
includes data from the 2012 Commodity Flow Survey (CFS), the Census
Bureau on international trade, as well as data associated with
construction, agriculture, utilities, warehouses, and other
industries. FAF4 estimates the modal choices for moving goods by
trucks, trains, boats, and other types of freight modes. It includes
traffic assignments, including truck flows on a network of truck
routes. https://ops.fhwa.dot.gov/freight/freight_analysis/faf/.
\175\ The same analysis estimated the population living within
100 meters of a FAF4 truck route is 41 million.
\176\ EPA. (2011) Exposure Factors Handbook: 2011 Edition.
Chapter 16. Online at https://www.epa.gov/sites/production/files/2015-09/documents/efh-Chapter16.pdf.
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As described in Section VII.H.1, we estimate that about 10 million
students attend schools within 200 meters of major roads.\177\ Research
into the impact of traffic-related air pollution on school performance
is tentative. A review of this literature found some evidence that
children exposed to higher levels of traffic-related air pollution show
poorer academic performance than those exposed to lower levels of
traffic-related air pollution.\178\ However, this evidence was judged
to be weak due to limitations in the assessment methods.
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\177\ Pedde, M.; Bailey, C. (2011) Identification of Schools
within 200 Meters of U.S. Primary and Secondary Roads. Memorandum to
the docket.
\178\ Stenson, C.; Wheeler, A.J.; Carver, A.; et al. (2021) The
impact of traffic-related air pollution on child and adolescent
academic performance: a systematic review. Environ Intl 155: 106696.
[Online at https://doi.org/10.1016/j.envint.2021.106696].
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While near-roadway studies focus on residents near roads or others
spending considerable time near major roads, the duration of commuting
results in another important contributor to overall exposure to
traffic-related air pollution. Studies of health that address time
spent in transit have found evidence of elevated risk of cardiac
impacts.179 180 181 Studies have also found that school bus
emissions can increase student exposures to diesel-related air
pollutants, and that programs that reduce school bus emissions may
improve health and reduce school absenteeism.182 183 184 185
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\179\ Riediker, M.; Cascio, W.E.; Griggs, T.R.; et al. (2004)
Particulate matter exposure in cars is associated with
cardiovascular effects in healthy young men. Am J Respir Crit Care
Med 169. [Online at https://doi.org/10.1164/rccm.200310-1463OC].
\180\ Peters, A.; von Klot, S.; Heier, M.; et al. (2004)
Exposure to traffic and the onset of myocardial infarction. New Engl
J Med 1721-1730. [Online at https://doi.org/10.1056/NEJMoa040203].
\181\ Adar, S.D.; Gold, D.R.; Coull, B.A.; (2007) Focused
exposure to airborne traffic particles and heart rate variability in
the elderly. Epidemiology 18: 95-103 [Online at: https://doi.org/10.1097/01.ede.0000249409.81050.46].
\182\ Sabin, L.; Behrentz, E.; Winer, A.M.; et al.
Characterizing the range of children's air pollutant exposure during
school bus commutes. J Expo Anal Environ Epidemiol 15: 377-387.
[Online at https://doi.org/10.1038/sj.jea.7500414].
\183\ Li, C.; N, Q.; Ryan, P.H.; School bus pollution and
changes in the air quality at schools: a case study. J Environ Monit
11: 1037-1042. [https://doi.org/10.1039/b819458k].
\184\ Austin, W.; Heutel, G.; Kreisman, D. (2019) School bus
emissions, student health and academic performance. Econ Edu Rev 70:
108-12.
\185\ Adar, S.D.; D. Souza, J.; Sheppard, L.; Adopting clean
fuels and technologies on school buses. Pollution and health impacts
in children. Am J Respir Crit Care Med 191. [Online at http://doi.org/10.1164/rccm.201410-1924OC].
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C. Environmental Effects Associated With Exposure to Pollutants
Impacted by This Rule
This section discusses the environmental effects associated with
pollutants affected by this rule, specifically PM, ozone,
NOX and air toxics.
1. Visibility
Visibility can be defined as the degree to which the atmosphere is
transparent to visible light.\186\ Visibility impairment is caused by
light scattering and absorption by suspended particles and gases. It is
dominated by contributions from suspended particles except under
pristine conditions. Visibility is important because it has direct
significance to people's enjoyment of daily activities in all parts of
the country. Individuals value good visibility for the well-being it
provides them directly, where they live and work, and in places where
they enjoy recreational opportunities. Visibility is also highly valued
in significant natural areas, such as national parks and wilderness
areas, and special emphasis is given to protecting visibility in these
areas. For more information on visibility see the final 2019 p.m.
ISA.\187\
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\186\ National Research Council, (1993). Protecting Visibility
in National Parks and Wilderness Areas. National Academy of Sciences
Committee on Haze in National Parks and Wilderness Areas. National
Academy Press, Washington, DC. This book can be viewed on the
National Academy Press website at https://www.nap.edu/catalog/2097/protecting-visibility-in-national-parks-and-wilderness-areas.
\187\ U.S. EPA. Integrated Science Assessment (ISA) for
Particulate Matter (Final Report, 2019). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
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EPA is working to address visibility impairment. Reductions in air
pollution from implementation of various programs associated with the
Clean Air Act Amendments of 1990 provisions have resulted in
substantial improvements in visibility and will continue to do so in
the future. Nationally, because trends in haze are closely associated
with trends in particulate sulfate and nitrate due to the relationship
between their concentration and light extinction, visibility trends
have improved as emissions of SO2 and NOX have
decreased over time due to air pollution regulations such as the Acid
Rain Program.\188\ However between 1990 and 2018, in the western part
of the country, changes in total light extinction were smaller, and the
contribution of particulate organic matter to atmospheric light
extinction was increasing due to increasing wildfire emissions.\189\
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\188\ U.S. EPA. Integrated Science Assessment (ISA) for
Particulate Matter (Final Report, 2019). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
\189\ Hand, J.L.; Prenni, A.J.; Copeland, S.; Schichtel, B.A.;
Malm, W.C. (2020). Thirty years of the Clean Air Act Amendments:
Impacts on haze in remote regions of the United States (1990-2018).
Atmos Environ 243: 117865.
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In the Clean Air Act Amendments of 1977, Congress recognized
visibility's value to society by establishing a national goal to
protect national parks and wilderness areas from visibility impairment
caused by manmade pollution.\190\ In 1999, EPA finalized the regional
haze program to protect the visibility in Mandatory Class I Federal
areas.\191\ There are 156 national parks, forests and wilderness areas
categorized as Mandatory Class I Federal areas.\192\ These areas are
defined in CAA section 162 as those national parks exceeding 6,000
acres, wilderness areas, and memorial parks exceeding 5,000 acres, and
all international parks which were in existence on August 7, 1977.
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\190\ See CAA section 169(a).
\191\ 64 FR 35714, July 1, 1999.
\192\ 62 FR 38680-38681, July 18, 1997.
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[[Page 4325]]
EPA has also concluded that PM2.5 causes adverse effects
on visibility in other areas that are not targeted by the Regional Haze
Rule, such as urban areas, depending on PM2.5 concentrations
and other factors such as dry chemical composition and relative
humidity (i.e., an indicator of the water composition of the
particles). The secondary (welfare-based) PM NAAQS provide protection
against visibility effects. In recent PM NAAQS reviews, EPA evaluated a
target level of protection for visibility impairment that is expected
to be met through attainment of the existing secondary PM standards.
2. Plant and Ecosystem Effects of Ozone
The welfare effects of ozone include effects on ecosystems, which
can be observed across a variety of scales, i.e., subcellular,
cellular, leaf, whole plant, population and ecosystem. When ozone
effects that begin at small spatial scales, such as the leaf of an
individual plant, occur at sufficient magnitudes (or to a sufficient
degree), they can result in effects being propagated along a continuum
to higher and higher levels of biological organization. For example,
effects at the individual plant level, such as altered rates of leaf
gas exchange, growth and reproduction, can, when widespread, result in
broad changes in ecosystems, such as productivity, carbon storage,
water cycling, nutrient cycling, and community composition.
Ozone can produce both acute and chronic injury in sensitive plant
species depending on the concentration level and the duration of the
exposure.\193\ In those sensitive species,\194\ effects from repeated
exposure to ozone throughout the growing season of the plant can tend
to accumulate, so even relatively low concentrations experienced for a
longer duration have the potential to create chronic stress on
vegetation.195 196 Ozone damage to sensitive plant species
includes impaired photosynthesis and visible injury to leaves. The
impairment of photosynthesis, the process by which the plant makes
carbohydrates (its source of energy and food), can lead to reduced crop
yields, timber production, and plant productivity and growth. Impaired
photosynthesis can also lead to a reduction in root growth and
carbohydrate storage below ground, resulting in other, more subtle
plant and ecosystems impacts.\197\ These latter impacts include
increased susceptibility of plants to insect attack, disease, harsh
weather, interspecies competition, and overall decreased plant vigor.
The adverse effects of ozone on areas with sensitive species could
potentially lead to species shifts and loss from the affected
ecosystems,\198\ resulting in a loss or reduction in associated
ecosystem goods and services. Additionally, visible ozone injury to
leaves can result in a loss of aesthetic value in areas of special
scenic significance like national parks and wilderness areas and
reduced use of sensitive ornamentals in landscaping.\199\ In addition
to ozone effects on vegetation, newer evidence suggests that ozone
affects interactions between plants and insects by altering chemical
signals (e.g., floral scents) that plants use to communicate to other
community members, such as attraction of pollinators.
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\193\ 73 FR 16486, March 27, 2008.
\194\ 73 FR 16491, March 27, 2008. Only a small percentage of
all the plant species growing within the U.S. (over 43,000 species
have been catalogued in the USDA PLANTS database) have been studied
with respect to ozone sensitivity.
\195\ U.S. EPA. Integrated Science Assessment (ISA) for Ozone
and Related Photochemical Oxidants (Final Report). U.S.
Environmental Protection Agency, Washington, DC, EPA/600/R-20/012,
2020.
\196\ The concentration at which ozone levels overwhelm a
plant's ability to detoxify or compensate for oxidant exposure
varies. Thus, whether a plant is classified as sensitive or tolerant
depends in part on the exposure levels being considered.
\197\ 73 FR 16492, March 27, 2008.
\198\ 73 FR 16493-16494, March 27, 2008. Ozone impacts could be
occurring in areas where plant species sensitive to ozone have not
yet been studied or identified.
\199\ 73 FR 16490-16497, March 27, 2008.
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The Ozone ISA presents more detailed information on how ozone
affects vegetation and ecosystems.200 201 The Ozone ISA
reports causal and likely causal relationships between ozone exposure
and a number of welfare effects and characterizes the weight of
evidence for different effects associated with ozone.\202\ The Ozone
ISA concludes that visible foliar injury effects on vegetation, reduced
vegetation growth, reduced plant reproduction, reduced productivity in
terrestrial ecosystems, reduced yield and quality of agricultural
crops, alteration of below-ground biogeochemical cycles, and altered
terrestrial community composition are causally associated with exposure
to ozone. It also concludes that increased tree mortality, altered
herbivore growth and reproduction, altered plant-insect signaling,
reduced carbon sequestration in terrestrial ecosystems, and alteration
of terrestrial ecosystem water cycling are likely to be causally
associated with exposure to ozone.
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\200\ U.S. EPA. Integrated Science Assessment (ISA) for Ozone
and Related Photochemical Oxidants (Final Report). U.S.
Environmental Protection Agency, Washington, DC, EPA/600/R-20/012,
2020.
\201\ U.S. EPA. Integrated Science Assessment (ISA) for Ozone
and Related Photochemical Oxidants (Final Report). U.S.
Environmental Protection Agency, Washington, DC, EPA/600/R-20/012,
2020.
\202\ The Ozone ISA evaluates the evidence associated with
different ozone related health and welfare effects, assigning one of
five ``weight of evidence'' determinations: causal relationship,
likely to be a causal relationship, suggestive of a causal
relationship, inadequate to infer a causal relationship, and not
likely to be a causal relationship. For more information on these
levels of evidence, please refer to Table II of the ISA.
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3. Atmospheric Deposition
The Integrated Science Assessment for Oxides of Nitrogen, Oxides of
Sulfur, and Particulate Matter--Ecological Criteria documents the
ecological effects of the deposition of these criteria air
pollutants.\203\ It is clear from the body of evidence that
NOX, oxides of sulfur (SOX), and PM contribute to
total nitrogen (N) and sulfur (S) deposition. In turn, N and S
deposition cause either nutrient enrichment or acidification depending
on the sensitivity of the landscape or the species in question. Both
enrichment and acidification are characterized by an alteration of the
biogeochemistry and the physiology of organisms, resulting in harmful
declines in biodiversity in terrestrial, freshwater, wetland, and
estuarine ecosystems in the United States. Decreases in biodiversity
mean that some species become relatively less abundant and may be
locally extirpated. In addition to the loss of unique living species,
the decline in total biodiversity can be harmful because biodiversity
is an important determinant of the stability of ecosystems and their
ability to provide socially valuable ecosystem services.
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\203\ U.S. EPA. Integrated Science Assessment (ISA) for Oxides
of Nitrogen, Oxides of Sulfur and Particulate Matter Ecological
Criteria (Final Report). U.S. Environmental Protection Agency,
Washington, DC, EPA/600/R-20/278, 2020.
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Terrestrial, wetland, freshwater, and estuarine ecosystems in the
United States are affected by N enrichment/eutrophication caused by N
deposition. These effects have been consistently documented across the
United States for hundreds of species. In aquatic systems increased N
can alter species assemblages and cause eutrophication. In terrestrial
systems N loading can lead to loss of nitrogen-sensitive lichen
species, decreased biodiversity of grasslands, meadows and other
sensitive habitats, and increased potential for invasive species. For a
broader explanation of the topics treated here, refer to the
description in Chapter 4 of the RIA.
The sensitivity of terrestrial and aquatic ecosystems to
acidification from N and S deposition is predominantly governed by
geology. Prolonged exposure to excess nitrogen and sulfur
[[Page 4326]]
deposition in sensitive areas acidifies lakes, rivers, and soils.
Increased acidity in surface waters creates inhospitable conditions for
biota and affects the abundance and biodiversity of fishes,
zooplankton, and macroinvertebrates and ecosystem function. Over time,
acidifying deposition also removes essential nutrients from forest
soils, depleting the capacity of soils to neutralize future acid
loadings and negatively affecting forest sustainability. Major effects
in forests include a decline in sensitive tree species, such as red
spruce (Picea rubens) and sugar maple (Acer saccharum).
Building materials including metals, stones, cements, and paints
undergo natural weathering processes from exposure to environmental
elements (e.g., wind, moisture, temperature fluctuations, sunlight,
etc.). Pollution can worsen and accelerate these effects. Deposition of
PM is associated with both physical damage (materials damage effects)
and impaired aesthetic qualities (soiling effects). Wet and dry
deposition of PM can physically affect materials, adding to the effects
of natural weathering processes, by potentially promoting or
accelerating the corrosion of metals, by degrading paints, and by
deteriorating building materials such as stone, concrete, and
marble.\204\ The effects of PM are exacerbated by the presence of
acidic gases and can be additive or synergistic due to the complex
mixture of pollutants in the air and surface characteristics of the
material. Acidic deposition has been shown to have an effect on
materials including zinc/galvanized steel and other metal, carbonate
stone (such as monuments and building facings), and surface coatings
(paints).\205\ The effects on historic buildings and outdoor works of
art are of particular concern because of the uniqueness and
irreplaceability of many of these objects. In addition to aesthetic and
functional effects on metals, stone, and glass, altered energy
efficiency of photovoltaic panels by PM deposition is also becoming an
important consideration for impacts of air pollutants on materials.
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\204\ U.S. EPA. Integrated Science Assessment (ISA) for
Particulate Matter (Final Report, 2019). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
\205\ Irving, P.M., e.d. 1991. Acid Deposition: State of Science
and Technology, Volume III, Terrestrial, Materials, Health, and
Visibility Effects, The U.S. National Acid Precipitation Assessment
Program, Chapter 24, page 24-76.
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4. Environmental Effects of Air Toxics
Emissions from producing, transporting, and combusting fuel
contribute to ambient levels of pollutants that contribute to adverse
effects on vegetation. VOCs, some of which are considered air toxics,
have long been suspected to play a role in vegetation damage.\206\ In
laboratory experiments, a wide range of tolerance to VOCs has been
observed.\207\ Decreases in harvested seed pod weight have been
reported for the more sensitive plants, and some studies have reported
effects on seed germination, flowering, and fruit ripening. Effects of
individual VOCs or their role in conjunction with other stressors
(e.g., acidification, drought, temperature extremes) have not been well
studied. In a recent study of a mixture of VOCs including ethanol and
toluene on herbaceous plants, significant effects on seed production,
leaf water content, and photosynthetic efficiency were reported for
some plant species.\208\
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\206\ U.S. EPA. (1991). Effects of organic chemicals in the
atmosphere on terrestrial plants. EPA/600/3-91/001.
\207\ Cape J.N., I.D. Leith, J. Binnie, J. Content, M. Donkin,
M. Skewes, D.N. Price, A.R. Brown, A.D. Sharpe. (2003). Effects of
VOCs on herbaceous plants in an open-top chamber experiment.
Environ. Pollut. 124:341-343.
\208\ Cape J.N., I.D. Leith, J. Binnie, J. Content, M. Donkin,
M. Skewes, D.N. Price, A.R. Brown, A.D. Sharpe. (2003). Effects of
VOCs on herbaceous plants in an open-top chamber experiment.
Environ. Pollut. 124:341-343.
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Research suggests an adverse impact of vehicle exhaust on plants,
which has in some cases been attributed to aromatic compounds and in
other cases to NOX.209 210 211 The impacts of
VOCs on plant reproduction may have long-term implications for
biodiversity and survival of native species near major roadways. Most
of the studies of the impacts of VOCs on vegetation have focused on
short-term exposure and few studies have focused on long-term effects
of VOCs on vegetation and the potential for metabolites of these
compounds to affect herbivores or insects.
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\209\ Viskari E-L. (2000). Epicuticular wax of Norway spruce
needles as indicator of traffic pollutant deposition. Water, Air,
and Soil Pollut. 121:327-337.
\210\ Ugrekhelidze D., F. Korte, G. Kvesitadze. (1997). Uptake
and transformation of benzene and toluene by plant leaves. Ecotox.
Environ. Safety 37:24-29.
\211\ Kammerbauer H., H. Selinger, R. Rommelt, A. Ziegler-Jons,
D. Knoppik, B. Hock. (1987). Toxic components of motor vehicle
emissions for the spruce Picea abies. Environ. Pollut. 48:235-243.
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III. Test Procedures and Standards
In applying heavy-duty criteria pollutant emission standards, EPA
divides engines primarily into two types: Compression ignition (CI)
(primarily diesel-fueled engines) and spark-ignition (SI) (primarily
gasoline-fueled engines). The CI standards and requirements also apply
to the largest natural gas engines. Battery-electric and fuel-cell
vehicles are also subject to criteria pollutant standards and
requirements. Criteria pollutant exhaust emission standards apply for
four criteria pollutants: Oxides of nitrogen (NOX),
particulate matter (PM), hydrocarbons (HC), and carbon monoxide
(CO).\212\ In this Section III we describe new emission standards that
will apply for these pollutants starting in MY 2027. We also describe
new and updated test procedures we are finalizing in this rule.
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\212\ Reference to hydrocarbon (HC) standards includes
nonmethane hydrocarbon (NMHC), nonmethane-nonethane hydrocarbon
(NMNEHC) and nonmethane hydrocarbon equivalent (NMHCE). See 40 CFR
86.007-11.
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Section III.A provides an overview of provisions that broadly apply
for this final rule. Section III.B and Section III.D include the new
laboratory-based standards and final updates to test procedures for
heavy-duty compression-ignition and spark-ignition engines,
respectively. Section III.C introduces the final off-cycle standards
and test procedures that apply for compression-ignition engines and
extend beyond the laboratory to on-the-road, real-world conditions.
Section III.E describes the new refueling standards we are finalizing
for certain heavy-duty spark-ignition engines. Each of these sections
describe the final new standards and their basis, as well as describe
the new test procedures and any updates to current test procedures, and
describe our rationale for the final program, including feasibility
demonstrations, available data, and comments received.
A. Overview
1. Migration and Clarifications of Regulatory Text
As noted in Section I of this preamble, we are migrating our
criteria pollutant regulations for model year 2027 and later heavy-duty
highway engines from their current location in 40 CFR Part 86, subpart
A, to 40 CFR Part 1036.\213\ Consistent with this migration, the
compliance provisions discussed in this preamble refer to the
regulations in their new location in part 1036. In general, this
migration is not intended to change the compliance program specified in
part 86, except as specifically finalized in this rulemaking. EPA
submitted a memorandum to the docket describing how we proposed to
migrate
[[Page 4327]]
certification and compliance provisions into 40 CFR part 1036.\214\
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\213\ As noted in the following sections, we are proposing some
updates to 40 CFR parts 1037, 1065, and 1068 to apply to other
sectors in addition to heavy-duty highway engines.
\214\ Stout, Alan; Brakora, Jessica. Memorandum to docket EPA-
HQ-OAR-2019-0055. ``Technical Issues Related to Migrating Heavy-Duty
Highway Engine Certification Requirements from 40 CFR part 86,
subpart A, to 40 CFR part 1036''. March 2022.
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i. Compression- and Spark-Ignition Engines Regulatory Text
For many years, the regulations of 40 CFR part 86 have referred to
``diesel heavy-duty engines'' and ``Otto-cycle heavy-duty engines'';
however, as we migrate the heavy-duty provisions of 40 CFR part 86,
subpart A, to 40 CFR part 1036 in this rule, we proposed to refer to
these engines as ``compression-ignition'' (CI) and ``spark-ignition''
(SI), respectively, which are more comprehensive terms and consistent
with existing language in 40 CFR part 1037 for heavy-duty motor vehicle
regulations. We also proposed to update the terminology for the primary
intended service classes in 40 CFR 1036.140 to replace Heavy heavy-duty
engine with Heavy HDE, Medium heavy-duty engine with Medium HDE, Light
heavy-duty engine with Light HDE, and Spark-ignition heavy-duty engine
with Spark-ignition HDE.\215\ We received no adverse comment and are
finalizing these terminology changes, as proposed. This final rule
revises 40 CFR parts 1036 and 1037 to reflect this updated terminology.
Throughout this preamble, reference to diesel and Otto-cycle engines
and the previous service class nomenclature is generally limited to
discussions relating to current test procedures and specific
terminology used in 40 CFR part 86. Heavy-duty engines not meeting the
definition of compression-ignition or spark-ignition are deemed to be
compression-ignition engines for purposes of part 1036, per 40 CFR
1036.1(c) and are subject to standards in 40 CFR 1036.104.
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\215\ This new terminology for engines is also consistent with
the ``HDV'' terminology used for vehicle classifications in 40 CFR
1037.140.
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ii. Heavy-Duty Hybrid Regulatory Text
Similar to our updates to more comprehensive and consistent
terminology for CI and SI engines, as part of this rule we are also
finalizing three main updates and clarifications to regulatory language
for hybrid engines and hybrid powertrains. First, as proposed, we are
finalizing an updated definition of ``engine configuration'' in 40 CFR
1036.801; the updated definition clarifies that an engine configuration
includes hybrid components if it is certified as a hybrid engine or
hybrid powertrain. Second, we are finalizing, as proposed, a
clarification in 40 CFR 1036.101(b) that regulatory references in part
1036 to engines generally apply to hybrid engines and hybrid
powertrains. Third, we are finalizing as proposed that manufacturers
may optionally test the hybrid engine and powertrain together, rather
than testing the engine alone. The option to test hybrid engine and
powertrain together allows manufacturers to demonstrate emission
performance of the hybrid technology that are not apparent when testing
the engine alone. If the emissions results of testing the hybrid engine
and powertrain together show NOX emissions lower than the
final standards, then EPA anticipates that manufacturers may choose to
participate in the NOX ABT program in the final rule (see
preamble Section IV.G for details on the final ABT program).
We requested comment on our proposed clarification in 40 CFR
1036.101(b) that manufacturers may optionally test the hybrid engine
and powertrain together, rather than testing the engine alone, and
specifically, whether EPA should require all hybrid engines and
powertrains to be certified together, rather than making it optional.
For additional details on our proposed updates and clarifications to
regulatory language for hybrid engines and hybrid powertrains, as well
as our specific requests for comment on these changes, see the proposed
rule preamble (87 FR 17457, March 28, 2022).
Several commenters support the proposal to allow manufacturers to
certify hybrid powertrains with a powertrain test procedure, but urge
EPA to continue to allow manufacturers to certify hybrid systems using
engine dynamometer testing procedures. These commenters stated that the
powertrain dynamometer test procedures produce emission results that
are more representative of hybrid engine or powertrain on-road
operation than engine-only testing, however, commenters also stated the
proposed test cycles are not reflective of real-world applications
where hybrid technology works well and urged EPA to finalize different
duty-cycles. In contrast, one commenter pointed to data collected from
light-duty hybrid electric vehicles in Europe that the commenter stated
shows hybrid-electric vehicles (HEVs) emit at higher levels than
demonstrated in current certification test procedures; based on those
data the commenter stated that EPA should not allow HEVs to generate
NOX emissions credits. Separately, some commenters also
stated that requiring powertrain testing for hybrid engines or hybrid
powertrains certification would add regulatory costs or other
logistical challenges.
After considering these comments, EPA has determined that
powertrain testing for hybrid systems should remain an option in this
final rule. This option allows manufacturers to demonstrate emission
performance of the hybrid technology, without requiring added test
burden or logistical constraints. We are therefore finalizing as
proposed the allowance for manufacturers to test the hybrid engine and
powertrain together. If testing the hybrid engine and hybrid powertrain
together results in NOX emissions that are below the final
standards, then manufacturers can choose to certify to a FEL below the
standard, and then generate NOX emissions credits as
provided under the final ABT program (see Section IV.G). We disagree
with one commenter who asserted that manufacturers should not be
allowed to generate NOX emissions credits from HEVs based on
data showing higher emissions from HEVs operating in the real-world
compared to certification test data in Europe. Rather, we expect the
powertrain test procedures we are finalizing will accurately reflect
NOX emissions from HEVs due to the specifications we are
including in the final test procedures, which differ from the
certification test procedures to which the commenter referred.\216\ See
preamble Section III.B.2.v for more details on the powertrain test
procedures that we are finalizing.
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\216\ We note that the data provided by the commenter was
specific to light-duty vehicles and evaluated CO2
emissions, not criteria pollutant emissions. EPA proposed and is
finalizing changes to the light-duty test procedures for HEVs; in
this Section III we focus on heavy-duty test procedures. See
preamble Section XI and RTC Section 32 for details on the light-duty
test procedures for HEVs.
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Similarly, we disagree with those commenters urging EPA to finalize
different duty-cycle tests to reflect hybrid real-world operations.
While the duty-cycles suggested by commenters would represent some
hybrid operations, they would not represent the duty-cycles of other
hybrid vehicle types. See Section 3 of the Response to Comments
document for additional details on our responses to comments on
different duty-cycles for hybrid vehicles, and responses to other
comments on hybrid engines and hybrid powertrains.
In addition to our three main proposed updates and clarifications
to regulatory language for hybrid engines and hybrid powertrain, we
also proposed that manufacturers would certify a hybrid engine or
hybrid powertrain to criteria pollutant
[[Page 4328]]
standards by declaring a primary intended service class of the engine
configuration using the proposed, updated 40 CFR 1036.140.\217\ Our
proposal included certifying to the same useful life requirements of
the primary intended service class, which would provide truck owners
and operators with similar assurance of durability regardless of the
powertrain configuration they choose. Finally, we proposed an update to
40 CFR 1036.230(e) such that engine configurations certified as a
hybrid engine or hybrid powertrain may not be included in an engine
family with conventional engines, which is consistent with the current
provisions. We received no adverse comment and are finalizing as
proposed these updates to 40 CFR 1036.140 and 1036.230(e).
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\217\ The current provisions of 40 CFR 1036.140 distinguish
classes based on engine characteristics and characteristics of the
vehicles for which manufacturers intend to design and market their
engines.
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iii. Heavy-Duty Zero Emissions Vehicles Regulatory Text
As part of this final rule we are also updating and consolidating
regulatory language for battery-electric vehicles and fuel cell
electric vehicles (BEVs and FCEVs), collectively referred to as zero
emissions vehicles (ZEVs). For ZEVs, we are finalizing as proposed a
consolidation and update to our regulations as part of a migration of
heavy-duty vehicle regulations from 40 CFR part 86 to 40 CFR part 1037.
In the HD GHG Phase 1 rulemaking, EPA revised the heavy-duty vehicle
and engine regulations to make them consistent with our regulatory
approach to electric vehicles (EVs) under the light-duty vehicle
program. Specifically, we applied standards for all regulated criteria
pollutants and GHGs to all heavy-duty vehicle types, including
EVs.\218\ Starting in MY 2016, criteria pollutant standards and
requirements applicable to heavy-duty vehicles at or below 14,000
pounds gross vehicle weight rating (GVWR) in 40 CFR part 86, subpart S,
applied to heavy-duty EVs above 14,000 pounds GVWR through the use of
good engineering judgment (see current 40 CFR 86.016-1(d)(4)). Under
the current 40 CFR 86.016-1(d)(4), heavy-duty vehicles powered solely
by electricity are deemed to have zero emissions of regulated
pollutants; this provision also provides that heavy-duty EVs may not
generate NOX or PM emission credits.
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\218\ 76 FR 57106, September 15, 2011.
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As proposed, this final rule consolidates certification
requirements for ZEVs over 14,000 pounds GVWR in 40 CFR part 1037 such
that manufacturers of ZEVs over 14,000 pounds GVWR will certify to
meeting the emission standards and requirements of 40 CFR part 1037.
There are no criterial pollutant emission standards in 40 CFR part
1037, so we state in a new 40 CFR 1037.102, with revisions from the
proposed rule, that heavy-duty vehicles without propulsion engines are
subject to the same criteria pollutant emission standards that apply
for engines under 40 CFR part 86, subpart A, and 40 CFR part 1036. We
further specify in the final 40 CFR 1037.102 that ZEVs are deemed to
have zero tailpipe emissions of criteria pollutants. As discussed in
Section IV.G, we are choosing not to finalize our proposal to allow
manufacturers to generate NOX emission credits from ZEVs if
the vehicle met certain proposed requirements. We are accordingly
carrying forward in the final 40 CFR 1037.102 a provisions stating that
manufacturers may not generate emission credits from ZEVs. We are
choosing not to finalize the proposed durability requirements for ZEVs,
but we may choose in a future action to reexamine this issue. We are
finalizing as proposed to continue to not allow heavy-duty ZEVs to
generate PM emission credits since we are finalizing as proposed not to
allow any manufacturer to generate PM emission credits for use in MY
2027 and later under the final ABT program presented in Section IV.G.
The provisions in existing and final 40 CFR 1037.5 defer to 40 CFR
86.1801-12 to clarify how certification requirements apply for heavy-
duty vehicles at or below 14,000 pounds GVWR. Emission standards and
certification requirements in 40 CFR part 86, subpart S, generally
apply for complete heavy-duty vehicles at or below 14,000 pounds GVWR.
We proposed to also apply emission standards and certification
requirements under 40 CFR part 86, subpart S, for all incomplete
vehicles at or below 14,000 pounds GVWR. We decided not to adopt this
requirement and are instead continuing to allow manufacturers to choose
whether to certify incomplete vehicles at or below 14,000 pounds GVWR
to the emission standards and certification requirements in either 40
CFR part 86, subpart S, or 40 CFR part 1037.
2. Numeric Standards and Test Procedures for Compression-Ignition and
Spark-Ignition Engines
As summarized in preamble Section I.B and detailed in this preamble
Section III, we are finalizing numeric NOX standards and
useful life periods that are largely consistent with the most stringent
proposed option for MY 2027. The specific standards are summarized in
Section III.B, Section 0, Section III.D, and Section III.E. As required
by CAA section 202(a)(3), EPA is finalizing new NOX, PM, HC,
and CO emission standards for heavy-duty engines that reflect the
greatest degree of emission reduction achievable through the
application of technology that we have determined would be available
for MY 2027, and in doing so have given appropriate consideration to
additional factors, namely lead time, cost, energy, and safety. For all
heavy-duty engine classes, the final numeric NOX standards
for medium- and high-load engine operations match the most stringent
standards proposed for MY 2027; for low-load operations we are
finalizing the most stringent standard proposed for any model year (see
III.B.2.iii for discussion).\219\ For smaller heavy-duty engine service
classes (i.e., light and medium heavy-duty engines CI and SI heavy-duty
engines), the numeric standards are combined with the longest useful
life periods we proposed. For the largest heavy-duty engines (i.e.,
heavy heavy-duty engines), the final numeric standards are combined
with the longest useful life mileage that we proposed for MY 2027. The
final useful life periods for the largest heavy-duty engines are 50
percent longer than today's useful life periods, which will play an
important role in ensuring continued emissions control while the
engines operate on the road. The final numeric emissions standards and
useful life periods for all heavy-duty engines are based on further
consideration of data included in the proposal from our engine
demonstration programs that show the final emissions standards are
feasible at the final useful life periods applicable to these each
heavy-duty engine service class. Our assessment of the data available
at the time of proposal is further supported by our evaluation of
additional information and public comments stating that the proposed
standards are feasible. Our technical assessments are primarily based
on results from testing several diesel engine and aftertreatment
systems at Southwest Research Institute and at EPA's National Vehicle
and Fuel Emissions Laboratory (NVFEL), as well as heavy-duty gasoline
engine testing conducted at NVFEL; we also
[[Page 4329]]
considered heavy-duty engine certification data submitted to EPA by
manufacturers, ANPR and NPRM comments, and other data submitted by
industry stakeholders or studies conducted by EPA, as more specifically
identified in the sections that follow.
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\219\ As proposed, we are finalizing a new test procedure for
heavy-duty CI engines to demonstrate emission control when the
engine is operating under low-load and idle conditions; this new
test procedure does not apply to heavy-duty SI engines (see Section
III.B.2.iii for additional discussion).
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After further consideration of the data included in the proposal,
as well as information submitted by commenters and additional data we
collected since the time of proposal, we are finalizing two updates
from our proposed testing requirements in order to ensure the greatest
emissions reductions technically achievable are met throughout the
final useful life periods; these updates are tailored to the larger
engine classes (medium and heavy heavy-duty engines). First, we are
finalizing a requirement for manufacturers to demonstrate before heavy
heavy-duty engines are in-use that the emissions control technology is
durable through a period of time longer than the final useful life
mileage. For these largest engines with the longest useful life
mileages, the extended laboratory durability demonstration will better
ensure the final standards will be met throughout the regulatory useful
life under real-world operations where conditions are more variable.
Second, we are finalizing an interim in-use compliance allowance that
applies when EPA evaluates whether heavy or medium heavy-duty engines
are meeting the final standards after these engines are in use in the
real-world. When combined with the final useful life values, we believe
the interim in-use compliance allowance will address concerns raised in
comments from manufacturers that the more stringent proposed MY 2027
standards would not be feasible to meet over the very long useful life
periods of heavy heavy-duty engines, or under the challenging duty-
cycles of medium heavy-duty engines. This interim, in-use compliance
allowance is generally consistent with our past practice (for example,
see 66 FR 5114, January 18, 2001); also consistent with past practice,
the compliance allowance is included as an interim provision that we
may reassess in the future through rulemaking based on the performance
of emissions controls over the final useful life periods for medium and
heavy heavy-duty engines.\220\ To set standards that result in the
greatest emission reductions achievable for medium and heavy heavy-duty
engines, we considered additional data that we and others collected
since the time of the proposal; these data show the significant
technical challenge of maintaining very low NOX emissions
throughout very long useful life periods for heavy heavy-duty engines,
and greater amounts of certain aging mechanisms over the long useful
life periods of medium heavy-duty engines. In addition to these data,
in setting the standards we gave appropriate consideration to costs
associated with the application of technology to achieve the greatest
emissions reductions in MY 2027 (i.e., cost of compliance for
manufacturers associated with the standards \221\) and other statutory
factors, including energy and safety. We determined that for heavy
heavy-duty engines the combination of: (1) The most stringent MY 2027
standards proposed, (2) longer useful life periods compared to today's
useful life periods, (3) targeted, interim compliance allowance
approach to in-use compliance testing, and (4) the extended durability
demonstration for emissions control technologies is appropriate,
feasible, and consistent with our authority under the CAA to set
technology-forcing criteria pollutant standards for heavy-duty engines
for their useful life.\222\ Similarly, for medium heavy-duty engines we
determined that the combination of the first three elements (i.e., most
stringent MY 2027 standards proposed, increase in useful life periods,
and interim compliance allowance for in-use testing) is appropriate,
feasible, and consistent with our CAA authority to set technology-
forcing criteria pollutant standards for heavy-duty engines for their
useful life.
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\220\ We plan to closely monitor the in-use emissions
performance of model year 2027 and later engines to determine the
long-term need for the interim compliance allowance. For example, we
intend to analyze the data from the manufacturer run in-use testing
program to compare how engines age in the field compared to how they
age in the laboratory.
\221\ More specifically, for this rule in setting the final
standards and consistent with CAA section 202(a)(3)(A), the cost of
compliance for manufacturers associated with the standards that EPA
gave appropriate consideration to includes the direct manufacturing
costs and indirect costs incurred by manufacturers associated with
meeting the final standards over the corresponding final useful life
values, given that this rule sets new more stringent standards
through both the numeric level of the standard and the length of the
useful life period.
\222\ CAA section 202(a)(3)(A) is a technology-forcing provision
and reflects Congress' intent that standards be based on projections
of future advances in pollution control capability, considering
costs and other statutory factors. See National Petrochemical &
Refiners Association v. EPA, 287 F.3d 1130, 1136 (D.C. Cir. 2002)
(explaining that EPA is authorized to adopt ``technology-forcing''
regulations under CAA section 202(a)(3)); NRDC v. Thomas, 805 F.2d
410, 428 n.30 (D.C. Cir. 1986) (explaining that such statutory
language that ``seek[s] to promote technological advances while also
accounting for cost does not detract from their categorization as
technology-forcing standards''); see also Husqvarna AB v. EPA, 254
F.3d 195 (D.C. Cir. 2001) (explaining that CAA sections 202 and 213
have similar language and are technology-forcing standards). In this
context, the term ``technology-forcing'' has a specific legal
meaning and is used to distinguish standards that may require
manufacturers to develop new technologies (or significantly improve
existing technologies) from standards that can be met using existing
off-the-shelf technology alone. Technology-forcing standards such as
those in this final rule do not require manufacturers to use
specific technologies.
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In addition to the final standards for the defined duty cycle and
off-cycle test procedures, the final standards include several other
provisions for controlling emissions from specific operations in CI or
SI engines. First, we are finalizing, as proposed, to allow CI engine
manufacturers to voluntarily certify to idle standards using a new idle
test procedure that is based on an existing California Air Resources
Board (CARB) procedure.\223\
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\223\ 13 CCR 1956.8 (a)(6)(C)--Optional NOX idling
emission standard.
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We are also finalizing two options for manufacturers to control
engine crankcase emissions. Specifically, manufacturers will be
required to either: (1) As proposed, close the crankcase, or (2)
measure and account for crankcase emissions using an updated version of
the current requirements for an open crankcase. We believe that either
will ensure that the total emissions are accounted for during
certification testing and throughout the engine operation during useful
life. See Section III.B for more discussion on both the final idle and
crankcase provisions.
For heavy-duty SI, we are finalizing as proposed a new refueling
emission standard for incomplete vehicles above 14,000 lb GVWR starting
in MY 2027.\224\ The final refueling standard is based on the current
refueling standard that applies to complete heavy-duty gasoline-fueled
vehicles. Consistent with the current evaporative emission standards
that apply for these same vehicles, we are finalizing a requirement
that manufacturers can use an engineering analysis to demonstrate that
they meet our final refueling standard. We are also adopting an
optional alternative phase-in compliance pathway that manufacturers can
opt into in lieu of being subject to this implementation date for all
incomplete heavy-duty vehicles above 14,000 pounds GVWR (see Section
III.E for details).
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\224\ Some vehicle manufactures sell their engines or
``incomplete vehicles'' (i.e., chassis that include their engines,
the frame, and a transmission) to body builders who design and
assemble the final vehicle.
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Consistent with our proposal, we are also finalizing several
provisions to
[[Page 4330]]
reduce emissions from a broader range of engine operating conditions.
First, we are finalizing new standards for our existing test procedures
to reduce emissions under medium- and high-load operations (e.g., when
trucks are traveling on the highway). Second, we are finalizing new
standards and a corresponding new test procedure to measure emissions
during low-load operations (i.e., the low-load cycle, LLC). Third, we
are finalizing new standards and updates to an existing test procedure
to measure emissions over the broader range of operations that occur
when heavy-duty engines are operating on the road (i.e., off-
cycle).\225\
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\225\ Duty-cycle test procedures measure emissions while the
engine is operating over precisely defined duty cycles in an
emissions testing laboratory and provide very repeatable emission
measurements. ``Off-cycle'' test procedures measure emissions while
the engine is not operating on a specified duty cycle; this testing
can be conducted while the engine is being driven on the road (e.g.,
on a package delivery route), or in an emission testing laboratory.
Both duty-cycle and off-cycle testing are conducted pre-production
(e.g., for certification) or post-production to verify that the
engine meets applicable duty-cycle or off-cycle emission standards
throughout useful life (see Section III for more discussion).
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The new, more stringent numeric standards for the existing
laboratory-based test procedures that measure emissions during medium-
and high-load operations will ensure significant emissions reductions
from heavy-duty engines. Without this final rule, these medium- and
high-load operations are projected to contribute the most to heavy-duty
NOX emissions in 2045.
We are finalizing as proposed a new LLC test procedure, which will
ensure demonstration of emission control under sustained low-load
operations. After further consideration of data included in the
proposal, as well as additional information from the comments
summarized in this section, we are finalizing the most stringent
numeric standard for the LLC that we proposed for any model year. As
discussed in our proposal, data from our CI engine demonstration
program showed that the lowest numeric NOX standard proposed
would be feasible for the LLC throughout a useful life period similar
to the useful life we are finalizing for the largest heavy-duty
engines. After further consideration of this data, and additional
support from data collected since the time of proposal, we are
finalizing the most stringent standard proposed for any model year.
We are finalizing new numeric standards and revisions to the
proposed off-cycle test procedure. We proposed updates to the current
off-cycle test procedure that included binning emissions measurements
based on the type of operation the engine is performing when the
measurement data is being collected. Specifically, we proposed that
emissions data would be grouped into three bins, based on if the engine
was operating in idle (Bin 1), low-load (Bin 2), or medium-to-high load
(Bin 3) operation. Given the different operational profiles of each of
the three bins, we proposed a separate standard for each bin. Based on
further consideration of data included in the proposal, as well as
additional support from our consideration of data provided by
commenters, we are finalizing off-cycle standards for two bins, rather
than three bins; correspondingly, we are finalizing a two-bin approach
for grouping emissions data collected during off-cycle test procedures.
Our evaluation of available information shows that two bins better
represent the differences in engine operations that influence emissions
(e.g., exhaust temperature, catalyst efficiency) and ensure sufficient
data is collected in each bin to allow for an accurate analysis of the
data to determine if emissions comply with the standard for each bin.
Preamble Section III.C further discusses the final off-cycle standards.
3. Implementation of the Final Program
As discussed in this section, we have evaluated the final standards
in terms of technological feasibility, lead time, and stability, and
given appropriate consideration to cost, energy, and safety, consistent
with the requirements in CAA section 202(a)(3). The final standards are
based on data from our CI and SI engine feasibility demonstration
programs that was included in the proposal, and further supported by
information submitted by commenters and additional data we collected
since the time of proposal. Our evaluation of available data shows that
the final standards and useful life periods are feasible and will
result in the greatest emission reductions achievable for MY 2027,
pursuant to CAA section 202(a)(3), giving appropriate consideration to
cost, lead time, and other factors. We note that CAA section 202(a)(3)
neither requires that EPA consider all the statutory factors equally
nor mandates a specific method of cost analysis; rather EPA has
discretion in determining the appropriate consideration to give such
factors.\226\ As discussed in the Chapter 3 of the RIA, the final
standards are achievable without increasing the overall fuel
consumption and CO2 emissions of the engine (1) for each of
the duty cycles (SET, FTP, and LLC), and (2) for the fuel mapping test
procedures defined in 40 CFR 1036.535 and 1036.540.\227\ Finally, the
final standards will have no negative impact on safety, based on the
existing use of these technologies in light-duty and heavy-duty engines
on the road today (see section 3 of the Response to Comments document
for additional discussion on our assessment that the final standards
will have no negative impact on safety). This includes the safety of
closed crankcase systems, which we received comment on. As discussed in
Section 3 of the RTC, one commenter stated that requiring closed
crankcases could increase the chance of engine run away caused by
combustion of engine oil that could enter the intake from the closed-
crankcase system. We disagree with the commenter since closed crankcase
systems are used on engines today with no adverse effect on safety;
however, we are providing flexibility for manufactures to meet the
final standards regarding crankcase emissions (see preamble Section
III.B.2.vi for details).
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\226\ See, e.g., Sierra Club v. EPA, 325 F.3d 374, 378 (D.C.
Cir. 2003) (explaining that similar technology forcing language in
CAA section 202(l)(2) ``does not resolve how the Administrator
should weigh all [the statutory] factors in the process of finding
the `greatest emission reduction achievable' ''); Husqvarna AB v.
EPA, 254 F.3d 195, 200 (D.C. Cir. 2001) (explaining that under CAA
section 213's similar technology-forcing authority that ``EPA did
not deviate from its statutory mandate or frustrate congressional
will by placing primary significance on the `greatest degree of
emission reduction achievable' '' or by considering cost and other
statutory factors as important but secondary).
\227\ The final ORVR requirements discussed in Section III.E
will reduce fuel consumed from gasoline fuel engines, but these fuel
savings will not be measured on the duty cycles since the test
procedures for these tests measure tailpipe emissions and do not
measure emissions from refueling. We describe our estimate of the
fuel savings in Chapter 7 of the RIA.
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While we have referenced a technology pathway for complying with
our standards (Chapter 3 of the RIA) that is consistent with CAA
section 202(a)(3), there are other technology pathways that
manufacturers may choose in order to comply with the performance-based
final standards. We did not rely on alternative technology pathways in
our assessment of the feasibility of the final standards, however,
manufacturers may choose from any number of technology pathways to
comply with the final standards (e.g., alternative fuels, including
biodiesel, renewable diesel, renewable natural gas, renewable propane,
or hydrogen in combination with relevant emissions aftertreatment
technologies, and electrification, including plug-in hybrid electric
vehicles, battery-electric or fuel cell
[[Page 4331]]
electric vehicles). As noted in Section I, we are finalizing a program
that will begin in MY 2027, which is the earliest year that standards
can begin to apply under CAA section 202(a)(3)(C).\228\ The final
NOX standards are a single-step program that reflect the
greatest emission reductions achievable starting in MY 2027, giving
appropriate consideration to costs and other factors. In this final
rule, we are focused on achieving the greatest emission reductions
achievable in the MY 2027 timeframe, and have applied our judgment in
determining the appropriate standards for MY 2027 under this authority
for a national program. As the heavy-duty industry continues to
transition to zero-emission technologies, EPA could consider additional
criteria pollutant standards for model years beyond 2027 in future
rules.
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\228\ Section 202(a)(3)(C) requires that standards under
202(a)(3)(A) apply no earlier than 4 years after promulgation, and
apply for no less than 3 model years.
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In the event that manufacturers start production of some engine
families sooner than four years from our final rule, we are finalizing
a provision for manufacturers to split the 2027 model year, with an
option for manufacturers to comply with the final MY 2027 standards for
all engines produced for that engine family in MY 2027. Specifically,
we are finalizing as proposed that a MY 2027 engine family that starts
production within four years of the final rule could comply with the
final MY 2027 standards for all engines produced for that engine family
in MY2027, or could split the engine family by production date in MY
2027 such that engines in the family produced prior to four years after
the date that the final rule is promulgated would continue to be
subject to the existing standards.229 230 The split model
year provision for MY 2027 provides assurance that all manufacturers,
regardless of when they start production of their engine families, will
have four years of lead time to the MY 2027 standards under this final
rule, while also maximizing emission reductions, which is consistent
with our CAA authority. This final rule is promulgated upon the date of
signature, upon which date EPA also provided this signed final rule to
manufacturers and other stakeholders by email and posted it on EPA's
public website.\231\
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\229\ See 40 CFR 86.007-11.
\230\ 40 CFR 1036.150(t).
\231\ This final rule will also be published in the Federal
Register, and the effective date runs from the date of publication
as specified in the DATES section. Note, non-substantive edits from
the Office of the Federal Register may appear in the published
version of the final rule.
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4. Severability
This final rule includes new and revised requirements for numerous
provisions under various aspects of the highway heavy-duty emission
control program, including numeric standards, test procedures,
regulatory useful life, emission-related warranty, and other
requirements. Further, as explained in Sections I and XI, it modernizes
and amends numerous other CFR parts for other standard-setting parts
for various specific reasons. Therefore, this final rule is a
multifaceted rule that addresses many separate things for independent
reasons, as detailed in each respective section of this preamble. We
intended each portion of this rule to be severable from each other,
though we took the approach of including all the parts in one
rulemaking rather than promulgating multiple rules to modernize each
part of the program.
For example, the following portions of this rulemaking are mutually
severable from each other, as numbered: (1) The emission standards in
section III; (2) warranty in Section IV.B.1; (3) OBD requirements in
Section IV.C; (4) inducements requirements in Section IV.D; (5) ABT
program in Section IV.G; (6) the migration and clarification of
regulatory text in Section III.A; and (7) other regulatory amendments
discussed in Section XI. Each emission standard in Section III is also
severable from each other emission standard, including for each duty-
cycle, off-cycle, and refueling standard; each pollutant; and each
primary intended service class. For example, the NOX
standard for the FTP duty-cycle for Heavy HDE is severable from all
other emission standards. Each of the migration and clarification
regulatory amendments in Section III.A is also severable from all the
other regulatory amendments in that Section, and each of the regulatory
amendments in Section XI is also severable from all the other
regulatory amendments in that Section. If any of the above portions is
set aside by a reviewing court, then we intend the remainder of this
action to remain effective, and the remaining portions will be able to
function absent any of the identified portions that have been set
aside. Moreover, this list is not intended to be exhaustive, and should
not be viewed as an intention by EPA to consider other parts of the
rule not explicitly listed here as not severable from other parts of
the rule.
B. Summary of Compression-Ignition Exhaust Emission Standards and Duty
Cycle Test Procedures
EPA is finalizing new NOX, PM, HC, and CO emission
standards for heavy-duty compression-ignition engines that will be
certified under 40 CFR part 1036.232 233 We are finalizing
new emission standards for our existing laboratory test cycles (i.e.,
SET and FTP) and finalizing new NOX, PM, HC and CO emission
standards based on a new LLC, as described in this section.\234\ The
standards for NOX, PM, and HC are in units of milligrams/
horsepower-hour instead of the grams/horsepower-hour used for existing
standards because using units of milligrams better reflects the
precision of the new standards, rather than adding multiple zeros after
the decimal place. Making this change will require updates to how
manufacturers report data to the EPA in the certification application,
but it does not require changes to the test procedures that define how
to determine emission values.
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\232\ See 40 CFR 1036.104.
\233\ See 40 CFR 1036.605 and Section XI.B of this preamble for
a discussion of engines installed in specialty vehicles.
\234\ See 40 CFR 1036.104.
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The final duty cycle emission standards in 40 CFR 1037.104 apply
starting in model year 2027. This final rule includes new standards
over the SET and FTP duty cycles currently used for certification, as
well as new standards over a new LLC duty cycle to ensure manufacturers
of compression-ignition engines are designing their engines to address
emissions in during lower load operation that is not covered by the SET
and FTP. The new standards are shown in Table III-1.
Table III-1--Final Duty Cycle Emission Standards for Light HDE, Medium HDE, and Heavy HDE
----------------------------------------------------------------------------------------------------------------
Model year 2027 and later
---------------------------------------------------------------
Duty cycle NOX \a\ mg/hp-
hr HC mg/hp-hr PM mg/hp-hr CO g/hp-hr
----------------------------------------------------------------------------------------------------------------
SET and FTP..................................... 35 60 5 6.0
[[Page 4332]]
LLC............................................. 50 140 5 6.0
----------------------------------------------------------------------------------------------------------------
\a\ An interim NOX compliance allowance of 15 mg/hp-hr applies for any in-use testing of Medium HDE and Heavy
HDE. Manufacturers will add the compliance allowance to the NOX standard that applies for each duty cycle and
for off-cycle Bin 2, for both in-use field testing and laboratory testing as described in 40 CFR part 1036,
subpart E. Note, the NOX compliance allowance doesn't apply to confirmatory testing described in 40 CFR
1036.235(c) or selective enforcement audits described in 40 CFR part 1068.
This Section III.B describes the duty cycle emission standards and
test procedures we are finalizing for compression-ignition engines. We
describe compression-ignition engine technology packages that
demonstrate the feasibility of achieving these standards in Section
III.B.3.ii. The proposed rule provided an extensive discussion of the
rationale and information supporting the proposed duty cycle standards
(87 FR 17460, March 28, 2022). Chapters 1, 2, and 3 of the RIA include
additional information related to the range of technologies to control
criteria emissions, background on applicable test procedures, and the
full feasibility analysis for compression-ignition engines. See also
section 3 of the Response to Comments for a detailed discussion of the
comments and how they have informed this final rule.
As part of this rulemaking, we are finalizing an increase in the
useful life for each engine class as described in Section IV.A. The
emission standards outlined in this section will apply for the longer
useful life periods and manufacturers will be responsible for
demonstrating that their engines will meet these standards as part of
the revisions to durability requirements described in Section IV.F. In
Section IV.G, we discuss the updates to the ABT program, including
updates to account for the three laboratory cycles (SET, FTP, and LLC)
with unique standards.
1. Background on Existing Duty Cycle Test Procedures and Standards
We begin by providing background information on the existing duty
cycle test procedures and standards as relevant to this final rule,
including the SET and FTP standards and test procedures, powertrain and
hybrid powertrain test procedures, test procedure adjustments to
account for production and measurement variability, and crankcase
emissions. Current criteria pollutant standards must be met by
compression-ignition engines over both the SET and FTP duty cycles. The
FTP duty cycles, which date back to the 1970s, are composites of a
cold-start and a hot-start transient duty cycle designed to represent
urban driving. There are separate FTP duty cycles for both SI and CI
engines. The cold-start emissions are weighted by one-seventh and the
hot-start emissions are weighted by six-sevenths.\235\ The SET is a
more recent duty cycle for diesel engines that is a continuous cycle
with ramped transitions between the thirteen steady-state modes.\236\
The SET does not include engine starting and is intended to represent
fully warmed-up operating modes not emphasized in the FTP, such as more
sustained high speeds and loads.
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\235\ See 40 CFR 86.007-11 and 40 CFR 86.008-10.
\236\ See 40 CFR 86.1362.
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Emission standards for criteria pollutants are currently set to the
same numeric value for SET and FTP test cycles, as shown in Table III-
2. Manufacturers of compression-ignition engines have the option under
the existing regulations to participate in our ABT program for
NOX and PM, as discussed in the background of Section
IV.G.\237\ These pollutants are subject to FEL caps under the existing
regulations of 0.50 g/hp-hr for NOX and 0.02 g/hp-hr for
PM.\238\
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\237\ See 40 CFR 86.007-15.
\238\ See 40 CFR 86.007-11.
Table III-2--Existing Part 86 Diesel-Cycle Engine Standards Over the SET and FTP Duty Cycles
----------------------------------------------------------------------------------------------------------------
PM \b\ (g/hp-
NOX \a\ (g/hp-hr) hr) HC (g/hp-hr) CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
0.20............................................................ 0.01 0.14 15.5
----------------------------------------------------------------------------------------------------------------
\a\ Engine families participating in the existing ABT program are subject to a FEL cap of 0.50 g/hp-hr for NOX.
\b\ Engine families participating in the existing ABT program are subject to a FEL cap of 0.02 g/hp-hr for PM.
EPA developed powertrain and hybrid powertrain test procedures for
the HD GHG Phase 2 Heavy-Duty Greenhouse Gas rulemaking (81 FR 73478,
October 25, 2016) with updates in the HD Technical Amendments final
rule (86 FR 34321, June 29, 2021).\239\ The powertrain and hybrid
powertrain tests allow manufacturers to directly measure the
effectiveness of the engine, the transmission, the axle and the
integration of these components as an input to the Greenhouse gas
Emission Model (GEM) for compliance with the greenhouse gas standards.
As part of the technical amendments, EPA updated the powertrain test
procedure to allow use of test cycles beyond the current GEM vehicle
drive cycles, to include the SET and FTP engine-based test cycles and
to facilitate hybrid powertrain testing (40 CFR 1036.510, 1036.512, and
1037.550).
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\239\ See 40 CFR 1037.550.
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These heavy-duty diesel-cycle engine standards are applicable for a
useful life period based on the primary intended service class of the
engine.\240\ For certification, manufacturers must demonstrate that
their engines will meet these standards throughout the useful life by
performing a durability test and applying a deterioration factor (DF)
to their certification value.\241\ Additionally, manufacturers must
adjust emission rates for engines with exhaust aftertreatment to
account for infrequent
[[Page 4333]]
regeneration events accordingly.\242\ To account for variability in
these measurements, as well as production variability, manufacturers
typically add margin between the DF plus infrequent regeneration
adjustment factor (IRAF) adjusted test result and the FEL. A summary of
the margins manufacturers have added for MY 2019 and newer engines is
summarized in Chapter 3.1.2 of the RIA.
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\240\ 40 CFR 86.004-2.
\241\ See 40 CFR 86.004-26(c) and (d) and 86.004-28(c) and (d).
\242\ See 40 CFR 1036.501(d).
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Current regulations restrict the discharge of crankcase emissions
directly into the ambient air. Blowby gases from gasoline engine
crankcases have been controlled for many years by sealing the crankcase
and routing the gases into the intake air through a positive crankcase
ventilation (PCV) valve. However, in the past there have been concerns
about applying a similar technology for diesel engines. For example,
high PM emissions venting into the intake system could foul
turbocharger compressors. As a result of this concern, diesel-fueled
and other compression-ignition engines equipped with turbochargers (or
other equipment) were not required to have sealed crankcases (see 40
CFR 86.007-11(c)). For these engines, manufacturers are allowed to vent
the crankcase emissions to ambient air as long as they are measured and
added to the exhaust emissions during all emission testing to ensure
compliance with the emission standards. Because all new highway heavy-
duty diesel engines on the market today are equipped with
turbochargers, they are not required to have closed crankcases under
the current regulations. Chapter 1.1.4 of the RIA describes EPA's
recent test program to evaluate the emissions from open crankcase
systems on two modern heavy-duty diesel engines. Results suggest HC and
CO emitted from the crankcase can be a notable fraction of overall
tailpipe emissions. By closing the crankcase, those emissions would be
rerouted to the engine or aftertreatment system to ensure emission
control.
2. Test Procedures and Standards
As described in Section III.B.3.ii, we have determined that the
technology packages evaluated for this final action can achieve the new
duty-cycle standards. We are finalizing a single set of standards that
take effect starting in MY 2027, including not only new numerical
standards for new and existing duty-cycles but also other new numerical
standards for revised off-cycles test procedures and compliance
provisions, longer useful life periods, and other requirements.
The final standards were derived to achieve the maximum feasible
emissions reductions from heavy-duty diesel engines for MY 2027,
considering lead time, stability, cost, energy, and safety. To
accomplish this, we evaluated what operation made up the greatest part
of the inventory, as discussed in Section VI.B, and what technologies
can be used to reduce emissions in these areas. As discussed in Section
I, we project that emissions from operation at low power, medium-to-
high power, and mileages beyond the current regulatory useful life of
the engine will account for the majority of heavy-duty highway
emissions in 2045. To achieve reductions in these three areas, we
identified options for cycle-specific standards to ensure that the
maximum achievable reductions are seen across the operating range of
the engine. As described in Section IV, we are finalizing an increase
in the regulatory useful life periods for each heavy-duty engine class
to ensure these new standards are met for a greater portion of the
engine's operational life. Also as described in Section IV, we are
separately lengthening the warranty periods for each heavy-duty engine
class, which is expected to help to maintain the benefits of the
emission controls for a greater portion of the engine's operational
life.
To achieve the goal of reducing emissions across the operating
range of the engine, we are finalizing standards for three duty cycles
(SET, FTP, and LLC). In finalizing these standards, we assessed the
performance of the best available aftertreatment systems under various
operating conditions. For example, we observed that these systems are
more effective at reducing NOX emissions at the higher
exhaust temperatures that occur at high engine power than they are at
reducing NOX emissions at low exhaust temperatures that
occur at low engine power. To achieve the maximum NOX
reductions from the engine at maximum power, the aftertreatment system
was designed to ensure that the downstream selective catalytic
reduction (SCR) catalyst was properly sized, diesel exhaust fluid (DEF)
was fully mixed with the exhaust gas ahead of the SCR catalyst and the
diesel oxidation catalyst (DOC) was designed to provide a molar ratio
of NO to NO2 of near one. The final standards for the FTP
and LLC are 80 to 90 percent, or more, lower as compared to current
standards, which will contribute to reductions in emissions under low
power operation and under cold-start conditions. The standards are
achievable by utilizing cylinder deactivation (CDA), dual-SCR
aftertreatment configuration, closed crankcase, and heated diesel
exhaust fluid (DEF) dosing. To reduce emissions under medium to high
power, the final standards for the SET are greater than 80 percent
lower as compared to current standards. The SET standards are
achievable by utilizing improvements to the SCR formulation, SCR
catalyst sizing, and improved mixing of DEF with the exhaust. Further
information about these technologies can be found in Chapters 1 and 3
of the RIA.
The final PM standards are set at a level that requires heavy-duty
engines to maintain the emissions performance of current diesel
engines. The final standards for HC and CO are set at levels that are
equivalent to the maximum emissions reductions achievable by spark-
ignition engines over the FTP, with the general intent of making the
final standards fuel neutral.243 244 Compared to current
standards, the final standards for the SET and FTP duty cycles are 50
percent lower for PM, 57 percent lower for HC, and 61 percent lower for
CO. Each of these standards are discussed in more detail in the
following sections.
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\243\ See Section III.D for a discussion of these standards as
they relate to Spark-ignition HDE.
\244\ See 65 FR 6728 (February 10, 2000) and 79 FR 23454 (April
28, 2014) for more discussion on the principle of fuel neutrality
applied in recent rulemakings for light-duty vehicle criteria
pollutant standards.
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For Heavy HDE, we are finalizing NOX standards to a
useful life of 650,000 miles with a durability demonstration out to
750,000 miles, as discussed later in Section III.B.2. We recognize the
greater demonstration burden of a useful life of 650,000 miles for
these engines, and after careful analysis are updating our DF
demonstration provisions to include two options for an accelerated
aging demonstration. However, we also are taking into account that
extending a durability demonstration, given that it is conducted in the
controlled laboratory environment, will better ensure the final
standards will be met throughout the longer final regulatory useful
life mileage of 650,000 miles when these engines are operating in the
real-world where conditions are more variable. We are thus requiring
the durability demonstration to show that the emission control system
hardware is designed to comply with the NOX standards out to
750,000 miles. As discussed further in Section III.B, the aging
demonstration out to 750,000 miles in a controlled laboratory
environment ensures that manufacturers are designing Heavy HDE to meet
the
[[Page 4334]]
final standards out to the regulatory useful life of 650,000 miles once
the engine is in the real-world, while reducing the risk of greater
real world uncertainties impacting emissions at the longest useful life
mileages in the proposed rule. This approach both sets standards that
result in the maximum emission reductions achievable in MY 2027 while
addressing the technical issues raised by manufacturers regarding
various uncertainties in variability and the degradation of system
performance over time due to contamination of the aftertreatment from,
for example, fuel contamination (the latter of which is out of the
manufacturer's control).
As discussed in Section III.B.3, we have assessed the feasibility
of the standards for compression-ignition engines by testing a Heavy
HDE equipped with cylinder CDA technology, closed crankcase, and dual-
SCR aftertreatment configuration with heated DEF dosing. The
demonstration work consisted of two phases. The first phase of the
demonstration was led by CARB and is referred to as CARB Stage 3. In
this demonstration the aftertreatment was chemically- and
hydrothermally-aged to the equivalent of 435,000 miles. During this
aging the emissions performance of the engine was assessed after the
aftertreatment was degreened \245\, at the equivalent of 145,000 miles,
290,000 miles and 435,000 miles. The second phase of the demonstration
was led by EPA and is referred to as the EPA Stage 3 engine. In this
phase, improvements were made to the aftertreatment by replacing the
zone-coated catalyzed soot filter with a separate DOC and diesel
particulate filter (DPF) that were chemically- and hydrothermally-aged
to the equivalent of 800,000 miles and improving the mixing of the DEF
with exhaust prior to the downstream SCR catalyst. The EPA Stage 3
engine was tested at an age equivalent to 435,000, 600,000, and 800,000
miles. We also tested two additional aftertreatment systems, referred
to as ``System A'' and ``System B,'' which are each also a dual-SCR
aftertreatment configuration with heated DEF dosing. However, they each
have unique catalyst washcoat formulation and the ``System A''
aftertreatment has greater SCR catalyst volume. The details of these
aftertreatment systems, along with the test results, can be found in
RIA Chapter 3.
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\245\ Degreening is a process by which the catalyst is broken in
and is critical in order to obtain a stable catalyst prior to
assessing the catalyst's performance characteristics.
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i. FTP
We are finalizing new emission standards for testing over the FTP
duty cycle, as shown in Table III-3.\246\ These brake-specific FTP
standards apply across the Heavy HDE, Medium HDE, and Light HDE primary
intended service classes over the useful life periods shown in Table
III-4.\247\ The numeric levels of the NOX FTP standards at
the time of certification are consistent with the most stringent
proposed for MY 2027; as summarized in Section III.A.2 and detailed in
this Section III.B we are also finalizing an interim, in-use compliance
allowance for Medium and Heavy HDEs. The numeric level of the PM and CO
FTP standards are the same as proposed, and the numeric level of the HC
FTP standard is consistent with the proposed Option 1 standard starting
in MY 2027. These standards have been shown to be feasible for
compression-ignition engines based on testing of the CARB Stage 3 and
EPA Stage 3 engine with a chemically- and hydrothermally-aged
aftertreatment system.\248\ The EPA Stage 3 engine, was aged to and
tested at the equivalent of 800,000 miles.\249\ EPA's System A
demonstration engine, was aged to and tested at the equivalent of
650,000 miles.\250\ The System B demonstration engine was not aged and
was only tested after it was degreened. A summary of the data used for
EPA's feasibility analysis can be found in Section III.B.3. See Section
III.B.3 for details on how we addressed compliance margin when setting
the standards, including discussion of the interim in-use testing
allowance for Medium and Heavy HDE for determining the interim in-use
testing standards for these primary intended service classes.
---------------------------------------------------------------------------
\246\ See 40 CFR 1036.510 for the FTP duty-cycle test procedure.
\247\ The same FTP duty-cycle standards apply for Spark-ignition
HDE as discussed in Section III.D.
\248\ See Section III.B.2 for a description of the engine.
\249\ For the EPA Stage 3 engine, the data at the equivalent of
435,000 and 600,000 miles were included in the preamble of the NPRM
and the data at the equivalent of 800,000 miles was added to the
docket on May 5th, 2022.
\250\ Due to the timing of when the data from the System A
system were available, the data were added to the public docket
prior to the signing of the final rule.
Table III-3--Final Compression-Ignition Engine Standards Over the SET and FTP Duty Cycles
----------------------------------------------------------------------------------------------------------------
NOX (mg/hp-hr)
Model year HC (mg/hp-hr) PM (mg/hp-hr) CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
2027 and later.................................. \a\ 35 60 5 6.0
----------------------------------------------------------------------------------------------------------------
\a\ An interim NOX compliance allowance of 15 mg/hp-hr applies for any in-use testing of Medium HDE and Heavy
HDE. Manufacturers will add the compliance allowance to the NOX standard that applies for each duty cycle and
for off-cycle Bin 2, for both in-use field testing and laboratory testing as described in 40 CFR part 1036,
subpart E. Note, the NOX compliance allowance doesn't apply to confirmatory testing described in 40 CFR
1036.235(c) or selective enforcement audits described in 40 CFR part 1068.
Table III-4--Useful Life Periods for Heavy-Duty Compression-Ignition Primary Intended Service Classes
----------------------------------------------------------------------------------------------------------------
Current (Pre-MY 2027) Final MY 2027 and later
Primary intended service class -----------------------------------------------------------------------------
Miles Years Hours Miles Years Hours
----------------------------------------------------------------------------------------------------------------
Light HDE \a\..................... 110,000 10 ........... 270,000 15 13,000
Medium HDE........................ 185,000 10 ........... 350,000 12 17,000
Heavy HDE......................... 435,000 10 22,000 650,000 11 32,000
----------------------------------------------------------------------------------------------------------------
\a\ Current useful life period for Light HDE for GHG emission standards is 15 years or 150,000 miles; we are not
revising GHG useful life periods in this final rule. See 40 CFR 1036.108(d).
[[Page 4335]]
As further discussed in Section III.B.3, taking into account
measurement variability of the PM measurement test procedure and the
low numeric level of the new PM standards, we believe PM emissions from
current diesel engines are at the lowest feasible level for standards
starting in MY 2027. As summarized in Section III.B.3.ii.b,
manufacturers are submitting certification data to the agency for
current production engines well below the existing PM standards over
the FTP duty cycle. Setting the new PM FTP standards lower than the
existing FTP PM standards, at 5 mg/hp-hr (0.005 g/hp-hr), ensures that
future engines will maintain the low level of PM emissions of the
current engines and not increase PM emissions. We received comment
stating that a 5 mg/hp-hr standard did not provide enough margin for
some engine designs and that a 7.5 mg/hp-hr would be a more appropriate
standard to maintain current PM emissions levels while providing enough
margin to account for the measurement variability of the PM measurement
test procedure. The reason submitted in comment to justify the 7.5 mg/
hp-hr standard was that data from the Stage 3 testing at Southwest
Research Institute (SwRI) shows that in some conditions PM values
exceed the 5 mg/hp-hr emission standard. EPA took a further look at
this data and determined that the higher PM emission data points occur
immediately following DPF ash cleaning, and that the PM level returns
to a level well below the 5 mg/hp-hr standards shortly after return to
service once a soot cake layer reestablishes itself in the DPF. EPA
concluded from this assessment that these very short-term elevations in
PM that occur after required maintenance of the DPF should not be the
basis for the stringency of the PM standards and that the standards are
feasible.
As noted earlier in this section, we are finalizing HC and CO FTP
standards based on the feasibility demonstration for SI engines. As
summarized in Section III.B.3.ii.b, manufacturers are submitting data
to the agency that show emissions performance for current production CI
engines that are well below the current standards. Keeping FTP
standards at the same value for all fuels is consistent with the
agency's approach to previous criteria pollutant standards. See Section
III.D for more information on how the numeric values of the HC and CO
standards were determined.
In the NPRM, we did not propose any changes to the weighting
factors for the FTP cycle for heavy-duty engines. The current FTP
weighting of cold-start and hot-start emissions was promulgated in 1980
(45 FR 4136, January 21, 1980). It reflects the overall ratio of cold
and hot operation for heavy-duty engines generally and does not
distinguish by engine size or intended use. We received comment to
change the weighting factors to reduce the effect of the cold start
portion of the FTP on the composite FTP emission results or to add 300
seconds of idle before the first acceleration in the cold start FTP to
reduce the emissions impact of the cold start on the first
acceleration. Duty-cycles are an approximation of the expected real-
world operation of the engine and no duty cycle captures all aspects of
the real-world operation. Changing the cold/hot weighting factors would
not fully capture all aspects of what really occurs in-use, and there
is precedent in experience and historical approach with the current \1/
7\ cold and \6/7\ hot weighting factors. Adding 300 seconds of idle to
the beginning of the FTP would simply reduce the stringency of the
standard by reducing the impact of cold start emissions, as the 300
seconds of idle would allow the aftertreatment to light off prior to
the first major acceleration in the FTP. Although the case can be made
that many vehicles idle for some amount of time after start up, any
attempt to add idle time before the first acceleration is simply an
approximation and this ``one size fits all'' approach doesn't afford an
improvement over the current FTP duty-cycle, nor does it allow
determination of cold start emissions where the vehicle is underway
shortly after start up. After considering these comments we are also
not including any changes to the weighting factors for the FTP duty-
cycle in this final rule.
For Heavy HDE, we are finalizing test procedures for the
determination of deterioration factors in 40 CFR 1036.245 that require
these engines to be aged to an equivalent of 750,000 miles, which is 15
percent longer than the regulatory useful life of those engines. As
explained earlier in this section, we are finalizing this requirement
for Heavy HDE to ensure the final NOX standard will be met
through the lengthy regulatory useful life of 650,000 miles. See
preamble Section IV.A for details on how we set the regulatory useful
life for Heavy HDE.
ii. SET
We are finalizing new emissions standards for testing over the SET
duty-cycle as shown in Table III-3. These brake-specific SET standards
apply across the Heavy HDE, Medium HDE, and Light HDE primary intended
service classes, as well as the SI HDE primary intended service class
as discussed in Section III.D, over the same useful life periods shown
in Table III-4. The numeric levels of the NOX SET standards
at the time of certification are consistent with the most stringent
standard proposed for MY 2027.\251\ The numeric level of the CO SET
standard is consistent with the most stringent standard proposed for MY
2027 for all CI engine classes.\252\ The numeric level of the PM SET
standard is the same as proposed, and the numeric level of the HC SET
standard is consistent with the proposed Option 1 standard starting in
MY 2027. Consistent with our current standards, we are finalizing the
same numeric values for the standards over the SET and FTP duty cycles
for the CI engine classes. As with the FTP cycle, the standards have
been shown to be feasible for compression-ignition engines based on
testing of the CARB Stage 3 and EPA Stage 3 engines with a chemically-
and hydrothermally-aged aftertreatment system. The EPA Stage 3 engine
was aged to and tested at the equivalent of 800,000 miles.\253\ EPA's
Team A demonstration engine was aged to and tested at the equivalent of
650,000 miles.\254\ See Section III.B.3 for details on how we addressed
compliance margin when setting the standards, including discussion of
the interim in-use testing allowance for Medium and Heavy HDEs for
determining the interim in-use testing standards for these primary
intended service classes. A summary of the data used for EPA's
feasibility analysis can be found in Section III.B.3.
---------------------------------------------------------------------------
\251\ As discussed in Section III.B.3, we are finalizing an
interim, in-use compliance allowance that applies when Medium and
Heavy HDE are tested in-use.
\252\ As explained in Section III.D.1.ii, the final Spark-
ignition HDE CO standard for the SET duty-cycle is 14.4 g/hp-hr.
\253\ For the EPA Stage 3 engine, the data at the equivalent of
435,000 and 600,000 miles were included in the preamble of the NPRM
and the data at the equivalent of 800,000 miles was added to the
docket on May 5th, 2022.
\254\ Due to the timing of when the data from the System A
system were available, the data were added to the public docket
prior to the signing of the final rule.
---------------------------------------------------------------------------
As with the PM standards for the FTP (see Section III.B.2.i), and
as further discussed in Section III.B.3, taking into account
measurement variability of the PM measurement test procedure and the
low numeric level of the new PM standards, we believe PM emissions from
current diesel engines are at the lowest feasible level for standards
starting in MY 2027. Thus, the PM standard for the SET duty-cycle is
intended to ensure that there is not an increase in PM emissions from
future engines. We are finalizing new PM SET
[[Page 4336]]
standards of 5 mg/hp-hr for the same reasons outlined for the FTP in
Section III.B.2.i. Also similar to the FTP (see Section III.B.2.i), we
are finalizing HC and CO SET standards based on the feasibility
demonstration for SI engines (see Section III.D).
We have also observed an industry trend toward engine down-
speeding--that is, designing engines to do more of their work at lower
engine speeds where frictional losses are lower. To better reflect this
trend in our duty cycle testing, in the HD GHG Phase 2 final rule we
promulgated new SET weighting factors for measuring CO2
emissions (81 FR 73550, October 25, 2016). Since we believe these new
weighting factors better reflect in-use operation of current and future
heavy-duty engines, we are finalizing application of these new
weighting factors to criteria pollutant measurement, as show in Table
III-5, for NOX and other criteria pollutants as well. To
assess the impact of the new test cycle on criteria pollutant
emissions, we analyzed data from the EPA Stage 3 engine that was tested
on both versions of the SET. The data summarized in Section
III.B.3.ii.a show that the NOX emissions from the EPA Stage
3 engine at an equivalent of 435,000 miles are slightly lower using the
SET weighting factors in 40 CFR 1036.510 versus the current SET
procedure in 40 CFR 86.1362. The lower emissions using the SET cycle
weighting factors in 40 CFR 1036.510 are reflected in the stringency of
the final SET standards.
Table III-5--Weighting Factors for the SET
------------------------------------------------------------------------
Weighting
Speed/% load factor (%)
------------------------------------------------------------------------
Idle.................................................... 12
A, 100.................................................. 9
B, 50................................................... 10
B, 75................................................... 10
A, 50................................................... 12
A, 75................................................... 12
A, 25................................................... 12
B, 100.................................................. 9
B, 25................................................... 9
C, 100.................................................. 2
C, 25................................................... 1
C, 75................................................... 1
C, 50................................................... 1
---------------
Total............................................... 100
Idle Speed.............................................. 12
Total A Speed........................................... 45
Total B Speed........................................... 38
Total C Speed........................................... 5
------------------------------------------------------------------------
iii. LLC
EPA is finalizing the addition of new standards for testing over
the new low-load duty-cycle, that will require CI engine manufacturers
to demonstrate that the emission control system maintains functionality
during low-load operation where the catalyst temperatures have
historically been found to be below the catalyst's operational
temperature (see Chapter 2.2.2 of the RIA). We believe the addition of
this LLC will complement the expanded operational coverage of our new
off-cycle testing requirements (see Section III.C).
During ``Stage 2'' of the CARB Low NOX Demonstration
program, SwRI and NREL developed several candidate cycles with average
power and duration characteristics intended to test current diesel
engine emission controls under three low-load operating conditions:
Transition from high- to low-load, sustained low-load, and transition
from low- to high-load.\255\ In September 2019, CARB selected the 92-
minute ``LLC Candidate #7'' as the low load cycle they adopted for
their Low NOX Demonstration program and subsequent Omnibus
regulation.256 257
---------------------------------------------------------------------------
\255\ California Air Resources Board. ``Heavy-Duty Low
NOx Program Public Workshop: Low Load Cycle
Development''. Sacramento, CA. January 23, 2019. Available online:
https://ww3.arb.ca.gov/msprog/hdlownox/files/workgroup_20190123/02-llc_ws01232019-1.pdf.
\256\ California Air Resources Board. Heavy-Duty Omnibus
Regulation. Available online: https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.
\257\ California Air Resources Board. ``Heavy-Duty Low
NOx Program: Low Load Cycle'' Public Workshop. Diamond
Bar, CA. September 26, 2019. Available online: https://ww3.arb.ca.gov/msprog/hdlownox/files/workgroup_20190926/staff/03_llc.pdf.
---------------------------------------------------------------------------
We are adopting CARB's Omnibus LLC as a new duty-cycle, the LLC.
This cycle is described in Chapter 2 of the RIA for this rulemaking and
the test procedures are specified in 40 CFR 1036.514. The LLC includes
applying the accessory loads defined in the HD GHG Phase 2 rule, that
were based on data submitted to EPA as part of the development of the
HD GHG Phase 2. These accessory loads are 1.5, 2.5 and 3.5 kW for Light
HDE, Medium HDE, and Heavy HDE engines, respectively. As detailed
further in section 3 of the Response to Comments, we received comments
that EPA should revise the accessory loads. One commenter provided
specific recommendations for engines installed in tractors but in all
cases commenters didn't provide data to support their comments; after
consideration of these comments and further consideration of the basis
of the proposal, we are finalizing the accessory loads for the LLC as
proposed. To allow vehicle level technologies to be recognized on this
cycle, we are including a powertrain test procedure option for the LLC.
More information on the powertrain test procedure can be found in
Section III.B.2.v. IRAF determination for the LLC follows the test
procedures defined in 40 CFR 1036.580, which are the same test
procedures used for the SET and FTP. The IRAF test procedures that
apply to the SET and FTP in 40 CFR 1065.680 are appropriate for the LLC
as the procedures in 40 CFR 1065.680 were developed to work with any
engine-based duty-cycle. We are finalizing as proposed that, while the
IRAF procedures in 40 CFR 1036.580 and 1065.680 require that
manufacturers determine an IRAF for the SET, FTP, and LLC duty cycles,
manufacturers may omit the adjustment factor for a given duty cycle if
they determine that infrequent regeneration does not occur over the
types of engine operation contained in the duty cycle as described in
40 CFR 1036.580(c).
The final emission standards for the LLC are presented in Table
III-6, over the useful life periods shown in Table III-4. The numeric
levels of the NOX LLC standards at the time of certification
are the most stringent proposed for any model year.\258\ The numeric
level of the PM and CO LLC standards are the same as proposed, and the
numeric level of the HC LLC standard is consistent with the proposed
Option 1 standard starting in MY 2027. As with the FTP cycle, these
standards have been shown to be feasible for compression-ignition
engines based on testing of the EPA Stage 3 demonstration engine with
chemically- and hydrothermally-aged aftertreatment system, and for the
LLC the data shows that the standards are feasible for all engine
service classes with available margins between the data and the
standards. The summary of this data along with how we addressed
compliance margin can be found in Section III.B.3, including discussion
of the interim in-use compliance allowance for Medium and Heavy HDEs
for determining the interim in-use
[[Page 4337]]
standards for these primary intended service classes.
---------------------------------------------------------------------------
\258\ As summarized in Section III.A.2 and detailed in this
Section III.B we are also finalizing an interim, in-use compliance
allowance for medium and heavy heavy-duty engines.
Table III-6--Compression-Ignition Engine Standards Over the LLC Duty Cycle
----------------------------------------------------------------------------------------------------------------
NOX (mg/hp-hr)
Model year PM (mg/hp-hr) HC (mg/hp-hr) CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
2027 and later.................................. \a\ 50 5 140 6.0
----------------------------------------------------------------------------------------------------------------
\a\ An interim NOX compliance allowance of 15 mg/hp-hr applies for any in-use testing of Medium HDE and Heavy
HDE. Manufacturers will add the compliance allowance to the NOX standard that applies for each duty cycle and
for off-cycle Bin 2, for both in-use field testing and laboratory testing as described in 40 CFR part 1036,
subpart E. Note, the NOX compliance allowance doesn't apply to confirmatory testing described in 40 CFR
1036.235(c) or selective enforcement audits described in 40 CFR part 1068.
We are finalizing an LLC PM standard of 5 mg/hp-hr for the same
reasons outlined for the FTP in Section III.B.2.i. We are finalizing HC
and CO standards based on data from the CARB and EPA Stage 3 engine
discussed in Section III.B.3. We are finalizing the same numeric
standard for CO on the LLC as we have for the SET and FTP cycles
because the demonstration data from the EPA Stage 3 engine shows that
CO emissions on the LLC are similar to CO emissions from the SET and
FTP. We are finalizing HC standards that are different than the
standards of the SET and FTP cycles, to reflect our assessment of the
performance of the EPA Stage 3 engine on the LLC. The data discussed in
Section III.B.3 of this preamble shows that the PM, HC, and CO
standards are feasible for both current and future new engines.
iv. Idle
CARB currently has an optional idle test procedure and accompanying
standard of 30 g/hr of NOX for diesel engines to be ``Clean
Idle Certified.''.\259\ In the CARB Omnibus rule, the CARB lowered the
optional NOX standard to 10 g/hr for MY 2024 to MY 2026
engines and 5 g/hr for MY 2027 and beyond. In the NPRM, we proposed
optional NOX idle standards with a corresponding idle test
procedure, with potentially different numeric levels of the
NOX idle standards for MY 2023, MY 2024 to MY 2026 engines,
and for MY 2027 and beyond, that would allow compression ignition
engine manufacturers to voluntarily choose to certify (i.e., it would
be optional for a manufacturer to include the idle standard in an EPA
certification but once included the idle standard would become
mandatory and full compliance would be required). We proposed to
require that the brake-specific HC, CO, and PM emissions during the
Clean Idle test may not exceed measured emission rates from the idle
mode in the SET or the idle segments of the FTP, in addition to meeting
the applicable idle NOX standard. We requested comment on
whether EPA should make the idle standards mandatory instead of
voluntary for MY 2027 and beyond, as well as whether EPA should set
clean idle standards for HC, CO, and PM emissions (in g/hr) rather than
capping the idle emissions for those pollutants based on the measured
emission levels during the idle mode in the SET or the idle segments of
the FTP. We also requested comment on the need for EPA to define a
label that would be put on the vehicles that are certified to the
optional idle standard.
---------------------------------------------------------------------------
\259\ 13 CCR 1956.8(a)(6)(C)--Optional NOX idling
emission standard.
---------------------------------------------------------------------------
We received comments on the EPA's proposal to adopt California's
Clean Idle NOX standard as a voluntary emission standard for
Federal certification.\260\ All commenters provided general support for
EPA's proposal to set idle standards for heavy duty engines, with some
qualifications. Some commentors supported making idle standards
mandatory, while others commented that the idle standards should be
optional. With regard to the level of the idle standard, there was
support from many commenters that the standards should be set at the
Proposed Option 1 levels or lower, while several manufactures stated
that 10 g/hr for certification and 15 g/hr in-use would be the lowest
feasible standards for NOX. One manufacturer commented that
EPA must set standards that do not increase CO2 emissions.
EPA has considered these comments, along with the available data
including the data from the EPA Stage 3 engine,\261\ and we are
finalizing optional idle standards in 40 CFR 1036.104(b) and a new idle
test procedure in 40 CFR 1036.525. The standards are based on CARB's
test procedure with revisions to not require the measurement of PM, HC
and CO,\262\ to allow compression-ignition engine manufacturers to
voluntarily certify to an idle NOX standard of 30.0 g/hr for
MY 2024 to MY 2026, which is consistent with proposed Option 1 for MY
2023. For MY 2027 and beyond, the final NOX idle standard is
10.0 g/hr, which is the same as proposed Option 2 for those MYs.
Manufacturers certifying to the optional idle standard must comply with
the standard and related requirements as if they were mandatory.
---------------------------------------------------------------------------
\260\ See RTC section 3.
\261\ See RIA Chapter 3 for a summary of the data collected with
the EPA Stage 3 engine run on the Clean Idle test in three
configurations. These data show that the MY 2027 and beyond, final
NOX idle standard of 10 g/hr is feasible through useful
life with margin, and show that an additional 5 g/hr in-use margin
is not justified.
\262\ 86.1360-2007.B.4, California Exhaust Emission Standards
and Test Procedures for 2004 and Subsequent Model Heavy-Duty Diesel
Engines and Vehicles, April 18, 2019.
---------------------------------------------------------------------------
We received comments stating that the proposed PM, HC, and CO
standards are unworkable since the standards are set at the level the
engine emits at during idle over the engine SET and FTP duty cycles and
that variability in the emissions between the different tests could
cause the engine to fail the idle PM, HC, and CO standards. EPA
recognized this issue in the proposal and requested comment on if EPA
should instead set PM, HC, and CO standards that are fixed and not
based on the emissions from the engine during the SET and FTP. EPA has
considered these comments and we are not finalizing the proposed
requirement to measure brake-specific HC, CO, and PM emissions during
the Clean Idle test for comparison to emission rates from the idle
modes in the SET or the idle segments of the FTP.\263\ The measurement
of these additional pollutants would create unnecessary test burden for
the manufacturers at this time, especially with respect to measuring PM
during idle segments of the SET or FTP as it would require running
duplicate tests or adding a PM sampler. Further, setting the PM, HC and
CO standards right at the idle emissions level of the engine on the SET
and FTP could cause false failures due to test-to-test variability from
either the SET or FTP, or the Clean Idle test itself.
[[Page 4338]]
Idle operation is included as part of off-cycle testing and the SET,
FTP, and LLC duty cycles; standards for off-cycle and duty-cycle
testing ensure that emissions of HC, CO, and PM are well controlled as
aftertreatment temperatures are not as critical to controlling these
pollutants over extended idle periods as they are for NOX.
We are therefore not requiring the measurement of these other
pollutants to meet EPA voluntary clean idle standards.
---------------------------------------------------------------------------
\263\ See 40 CFR 1036.104(b).
---------------------------------------------------------------------------
We are finalizing a provision in new 40 CFR 1036.136 requiring
engine manufacturers that certify to the Federal Clean Idle
NOX standard to create stickers to identify their engines as
meeting the Federal Clean Idle NOX standard. The regulatory
provisions require that the stickers meet the same basic requirements
that apply for stickers showing that engines meet CARB's Clean Idle
NOX standard. For example, stickers must be durable and
readable throughout each vehicle's operating life, and the preferred
placement for Clean Idle stickers is on the driver's side of the hood.
Engine manufacturers must provide exactly the right number of these
stickers to vehicle manufacturers so they can apply the stickers to
vehicles with the engines that the engine manufacturer has certified to
meet the Federal Clean Idle NOX standard. If engine
manufacturers install engines in their own vehicles, they must apply
the stickers themselves to the appropriate vehicles. Engine
manufacturers must keep the following records for at least five years:
(1) Written documentation of the vehicle manufacturer's request for a
certain number of stickers, and (2) tracking information for stickers
the engine manufacturer sends and the date they sent them. 40 CFR
1036.136 also clarifies that the provisions in 40 CFR 1068.101 apply
for the Clean Idle sticker in the same way that those provisions apply
for emission control information labels. For example, manufacturing,
selling, and applying false labels are all prohibited actions subject
to civil penalties.
v. Powertrain
EPA recently finalized a separate rulemaking that included an
option for manufacturers to certify a hybrid powertrain to the SET and
FTP greenhouse gas engine standards by using a powertrain test
procedure (86 FR 34321, June 29, 2021).\264\ In this rulemaking, we are
similarly finalizing as proposed that manufacturers may certify hybrid
powertrains to criteria pollutant emissions standards by using the
powertrain test procedure. In this section we describe how
manufacturers would apply the powertrain test procedure to certify
hybrid powertrains.
---------------------------------------------------------------------------
\264\ The powertrain test procedure was established in the GHG
Phase 1 rulemaking but the recent rulemaking included adjustments to
apply the test procedure to the engine test cycles.
---------------------------------------------------------------------------
a. Development of Powertrain Test Procedures
Powertrain testing allows manufacturers to demonstrate emission
benefits that cannot be captured by testing an engine alone on a
dynamometer. For hybrid engines and powertrains, powertrain testing
captures when the engine operates less or at lower power levels due to
the use of the hybrid powertrain function. However, powertrain testing
requires the translation of an engine test procedure to a powertrain
test procedure. Chapter 2 of the RIA describes how we translated the
SET, FTP, and LLC engine test cycles to the powertrain test
cycles.\265\ The two primary goals of this process were to make sure
that the powertrain version of each test cycle was equivalent to each
respective engine test cycle in terms of positive power demand versus
time and that the powertrain test cycle had appropriate levels of
negative power demand. To achieve this goal, over 40 engine torque
curves were used to create the powertrain test cycles.
---------------------------------------------------------------------------
\265\ As discussed in Section III.B.1, as part of the technical
amendments rulemaking, EPA finalized that manufacturers may use the
powertrain test procedure for GHG emission standards on the FTP and
SET engine-based test cycles. In this rulemaking we are extending
this to allow the powertrain test procedure to be used for criteria
emission standards on these test cycles and the LLC. As discussed in
Section 2.ii, we are setting new weighting factors for the engine-
based SET procedure for criteria pollutant emissions, which are
reflected in the SET powertrain test cycle.
---------------------------------------------------------------------------
b. Testing Hybrid Engines and Hybrid Powertrains
As noted in the introduction of this Section III, we are finalizing
clarifications in 40 CFR 1036.101 that manufacturers may optionally
test the hybrid engine and hybrid powertrain to demonstrate compliance.
We are finalizing as proposed with one clarification that the
powertrain test procedures specified in 40 CFR 1036.510 and 1036.512,
which were previously developed for demonstrating compliance with GHG
emission standards on the SET and FTP test cycles, are applicable for
demonstrating compliance with criteria pollutant standards on the SET
and FTP test cycles. The clarification in 40 CFR 1036.510 provides
direction that the idle points in the SET should be run as neutral or
parked idle. In addition, for GHG emission standards we are finalizing
updates to 40 CFR 1036.510 and 1036.512 to further clarify how to carry
out the test procedure for plug-in hybrids. We have done additional
work for this rulemaking to translate the LLC to a powertrain test
procedure, and we are finalizing that manufacturers can similarly
certify hybrid engines and hybrid powertrains to criteria pollutant
emission standards on the LLC using the test procedures defined in 40
CFR 1036.514.
We are allowing manufacturers to use the powertrain test procedures
to certify hybrid engine and powertrain configurations to all MY 2023
and later criteria pollutant engine standards. Manufacturers can choose
to use either the SET duty-cycle in 40 CFR 86.1362 or the SET in 40 CFR
1036.510 in model years prior to 2027, and may use only the SET in 40
CFR 1036.510 for model year 2027 and beyond.\266\ \267\
---------------------------------------------------------------------------
\266\ We are allowing either the SET duty-cycle in 40 CFR
86.1362 or 40 CFR 1036.505 because the duty cycles are similar and,
as shown in Chapter 3.1.2 of the RIA, the criteria pollutant
emissions level of current production engines is similar between the
two cycles.
\267\ Prior to MY 2027, only manufacturers choosing to
participate in the 2026 Service Class Pull Ahead Credits, Full
Credits, or Partial Credits pathways under the Transitional Credits
Program need to conduct LLC powertrain testing (see Section IV.G for
details on).
---------------------------------------------------------------------------
We are allowing the use of these procedures starting in MY 2023 for
plug-in hybrids and, consistent with the requirements for light-duty
plug-in hybrids, we are finalizing that the applicable criteria
pollutant standards must be met under the worst-case conditions, which
is achieved by testing and evaluating emission under both charge-
depleting and charge-sustaining operation. This is to ensure that under
all drive cycles the powertrain meets the criteria pollutant standards
and is not based on an assumed amount of zero emissions range. We
received comment stating that the charge-depleting and charge-
sustaining operation should be weighted together for criteria
pollutants as well as GHG pollutants, but consistent with the light-
duty test procedure we want to ensure that criteria pollutant emissions
are controlled under all conditions, which would include under
conditions where the vehicle is not charged and is only operated in
charge sustaining-operation.
We are finalizing changes to the test procedures defined in 40 CFR
1036.510 and 1036.512 to clarify how to weight together the charge-
depleting and charge-sustaining greenhouse gas emissions for
determining the greenhouse gas emissions of plug-in
[[Page 4339]]
hybrids for the SET and FTP duty cycles. This weighting is done using
an application specific utility factor curve that is approved by EPA.
We are also finalizing a provision to not apply the cold and hot
weighting factors for the determination of the FTP composite emission
result for greenhouse gas pollutants because the charge-depleting and
sustaining test procedures finalized in 40 CFR 1036.512 include both
cold and hot start emissions by running repeat FTP cycles back-to-back.
By running back-to-back FTPs, the finalized test procedure captures
both cold and hot emissions and their relative contribution to daily
greenhouse gas emissions per unit work, removing the need for weighting
the cold and hot emissions.
We are finalizing the application of the powertrain test procedure
only for hybrid powertrains, to avoid having two different testing
pathways (engine only and powertrain) for non-hybrid engines for the
same standards. That said, we recognize there may be other technologies
where the emissions performance is not reflected on the engine test
procedures, so in such cases manufacturers may seek approval from EPA
to use the powertrain test procedure for non-hybrid engines and
powertrains consistent with 40 CFR 1065.10(c)(1).
Finally, for all pollutants, we requested comment on if we should
remove 40 CFR 1037.551 or limit the use of it to only selective
enforcement audits (SEAs). 40 CFR 1037.551 was added as part of the HD
GHG Phase 2 rulemaking to provide flexibility for an SEA or a
confirmatory test, by allowing just the engine of the powertrain to be
tested. Allowing just the engine to be tested over the engine speed and
torque cycle that was recorded during the powertrain test enables the
testing to be conducted in more widely available engine dynamometer
test cells, but this flexibility could increase the variability of the
test results. We didn't receive any comments on this topic and, for the
reason just stated, we are limiting the use of 40 CFR 1037.551 to SEA
testing.
vi. Crankcase Emissions
During combustion, gases can leak past the piston rings sealing the
cylinder and into the crankcase. These gases are called blowby gases
and generally include unburned fuel and other combustion products.
Blowby gases that escape from the crankcase are considered crankcase
emissions (see 40 CFR 86.402-78). Current regulations restrict the
discharge of crankcase emissions directly into the ambient air. Blowby
gases from gasoline engine crankcases have been controlled for many
years by sealing the crankcase and routing the gases into the intake
air through a PCV valve. However, in the past there have been concerns
about applying a similar technology for diesel engines. For example,
high PM emissions venting into the intake system could foul
turbocharger compressors. As a result of this concern, diesel-fueled
and other compression-ignition engines equipped with turbochargers (or
other equipment) were not required to have sealed crankcases (see 40
CFR 86.007-11(c)). For these engines, manufacturers were allowed to
vent the crankcase emissions to ambient air as long as they are
measured and added to the exhaust emissions during all emission testing
to ensure compliance with the emission standards.
Because all new highway heavy-duty diesel engines on the market
today are equipped with turbochargers, they are not required to have
closed crankcases under the current regulations. We estimate
approximately one-third of current highway heavy-duty diesel engines
have closed crankcases, indicating that some heavy-duty engine
manufacturers have developed systems for controlling crankcase
emissions that do not negatively impact the turbocharger. EPA proposed
provisions in 40 CFR 1036.115(a) to require a closed crankcase
ventilation system for all highway compression-ignition engines to
prevent crankcase emissions from being emitted directly to the
atmosphere starting for MY 2027 engines.\268\ Comments were received
regarding concerns closing the crankcase that included coking, degraded
performance and turbo efficiencies leading to increased CO2
emissions, secondary damage to components, and increased engine-out PM
(see section 3 of the Response to Comments document for further
details). After considering these comments, we are finalizing a
requirement for manufacturers to use one of two options for controlling
crankcase emissions, either: (1) As proposed, closing the crankcase, or
(2) an updated version of the current requirements for an open
crankcase that includes additional requirements for measuring and
accounting for crankcase emissions. We believe that either approach is
appropriate, so long as the total emissions are accounted for during
certification and in-use testing through useful life (including full
accounting for crankcase emission deterioration).
---------------------------------------------------------------------------
\268\ We proposed to move the current crankcase emissions
provisions to a new paragraph (u) in the interim provisions of 40
CFR 1036.150, which would apply through model year 2026.
---------------------------------------------------------------------------
a. Closed Crankcase Option
As EPA explained at proposal, the environmental advantages to
closing the crankcase are twofold. While the exception in the current
regulations for certain compression-ignition engines requires
manufacturers to quantify their engines' crankcase emissions during
certification, they report non-methane hydrocarbons in lieu of total
hydrocarbons. As a result, methane emissions from the crankcase are not
quantified. Methane emissions from diesel-fueled engines are generally
low; however, they are a concern for compression-ignition-certified
natural gas-fueled heavy-duty engines because the blowby gases from
these engines have a higher potential to include significant methane
emissions. We note that in the HD GHG Phase 2 rule we set methane
standards which required natural gas engines to close the crankcase in
order to comply with the methane standard. EPA proposed to require that
all natural gas-fueled engines have closed crankcases in the HD GHG
Phase 2 rulemaking, but opted to wait to finalize any updates to
regulations in a future rulemaking, where we could then propose to
apply these requirements to natural gas-fueled engines and to the
diesel fueled engines that many of the natural gas-fueled engines are
based off of (81 FR 73571, October 25, 2016).
In addition to our concern of unquantified methane emissions, we
believe another benefit to closed crankcases would be reduced engine
wear due to improved engine component durability. We know that the
performance of piston seals reduces as the engine ages, which would
allow more blowby gases and could increase crankcase emissions. While
crankcase emissions are currently included in the durability tests that
estimate an engine's deterioration at useful life, those tests were not
designed to capture the deterioration of the crankcase. These
unquantified age impacts continue throughout the operational life of
the engine. Closing crankcases could be a means to ensure those
emissions are addressed long-term to the same extent as other exhaust
emissions.
After considering all of the manufacturer concerns, we still
believe, noting that one-third of current highway heavy-duty diesel
engines have closed crankcases, that improvements in the design of
engine hardware would allow manufacturers to close the crankcase, with
the potential for increased maintenance intervals on some
[[Page 4340]]
components. For these reasons, EPA is finalizing provisions in 40 CFR
1036.115(a) to require a closed crankcase ventilation system as one of
two options for all highway compression-ignition engines to control
crankcase emissions for MY 2027 and later engines.
b. Open Crankcase Option
Given consideration of the concerns from commenters regarding
engine hardware durability associated with closing the crankcase, we
have decided to finalize an option that allows the crankcase to remain
open. This option requires manufacturers of compression ignition
engines that choose to leave the crankcase open to account for any
increase in the contribution of crankcase emissions (due to reduction
in performance of piston seals, etc.) to the total emissions from the
engine throughout the engine's useful life. Manufacturers that choose
to perform engine dynamometer-based testing out to useful life will
provide a deterioration factor that includes deteriorated crankcase
emissions because the engine components will be aged out to the
engine's useful life. Manufacturers that choose to use the accelerated
aging option in 40 CFR 1036.245(b), where the majority of the emission
control system aging is done, must use good engineering judgment to
determine the impact of engine deterioration on crankcase emissions and
adjust the tailpipe emissions at useful life to reflect this
deterioration. For example, manufacturers may determine deteriorated
crankcase emissions from the assessment of field-aged engines.
Manufacturers who choose this option must also account for
crankcase criteria pollutant emissions during any manufacturer run in-
use testing to determine the overall compliance of the engine as
described in 40 CFR 1036.415(d)(2). The crankcase emissions must be
measured separately from the tailpipe emissions or be routed into the
exhaust system, downstream from the last catalyst in the aftertreatment
system, to ensure that there is proper mixing of the two streams prior
to the sample point. In lieu of these two options, manufacturers may
use the contribution of crankcase emissions over the FTP duty-cycle at
useful life from the deterioration factor determination testing in 40
CFR 1036.245, as described in 40 CFR 1036.115(a) and add them to the
binned emission results determined in 40 CFR 1036.530.
Chapter 1.1.4 of the RIA describes EPA's recent test program to
evaluate the emissions from open crankcase systems on two modern heavy-
duty diesel engines. Results suggest HC and CO emitted from the
crankcase can be a notable fraction of overall tailpipe emissions. By
closing the crankcase, those emissions would be rerouted to the engine
or aftertreatment system to ensure control of the crankcase emissions.
If a manufacturer chooses the option to keep the crankcase open,
overall emission control will still be achieved, but the manufacturer
will have to design and optimize the emission control system for lower
tailpipe emissions to offset the emissions from the crankcase as the
total emissions are accounted for both in-use and at useful life.
3. Feasibility of the Diesel (Compression-Ignition) Engine Standards
i. Summary of Technologies Considered
Our finalized standards for compression-ignition engines are based
on the performance of technology packages described in Chapters 1 and 3
of the RIA for this rulemaking. Specifically, we are evaluating the
performance of next-generation catalyst formulations in a dual SCR
catalyst configuration with a smaller SCR catalyst as the first
substrate in the aftertreatment system for improved low-temperature
performance, and a larger SCR catalyst downstream of the diesel
particulate filter to improve NOX conversion efficiency
during high power operation and to allow for passive regeneration of
the particulate filter.\269\ Additionally, the technology package
includes CDA that reduces the number of active cylinders, resulting in
increased exhaust temperatures for improved catalyst performance under
light-load conditions and can be used to reduce fuel consumption and
CO2 emissions. The technology package also includes the use
of a heated DEF injector for the upfront SCR catalyst; the heated DEF
injector allows DEF injection at temperatures as low as approximately
140[deg]C. The heated DEF injector also improves the mixing of DEF and
exhaust gas within a shorter distance than with unheated DEF injectors,
which enables the aftertreatment system to be packaged in a smaller
space. Finally, the technology package includes hardware needed to
close the crankcase of diesel engines.
---------------------------------------------------------------------------
\269\ As described in Chapter 3 of the RIA, we are evaluating 3
different aftertreatment systems that contain different catalyst
formulation.
---------------------------------------------------------------------------
ii. Summary of Feasibility Analysis
a. Projected Technology Package Effectiveness and Cost
Based upon data from EPA's and CARB's Stage 3 Heavy-duty Low
NOX Research Programs (see Chapter 3.1.1.1 and Chapter
3.1.3.1 of the RIA), an 80 percent reduction in the Heavy HDE
NOX standard as compared to the current NOX
standard is technologically feasible when using CDA or other
valvetrain-related air control strategies in combination with dual SCR
systems, and closed crankcase. As noted in the proposal, EPA continued
to evaluate aftertreatment system durability via accelerated aging of
advanced emissions control systems as part of EPA's diesel engine
demonstration program that is described in Chapter 3 of the RIA. In
assessing the technical feasibility of each of our final standards, we
have taken into consideration the emissions of the EPA Stage 3 engine
and other available data, the additional emissions from infrequent
regenerations, the final longer useful life, test procedure
variability, emissions performance of other child engines in an engine
family, production and engine variability, fuel and DEF quality,
sulfur, soot and ash levels on the aftertreatment, aftertreatment aging
due to severe-service operation, aftertreatment packaging and lead time
for manufacturers.
Manufacturers are required to design engines that meet the duty
cycle and off-cycle standards throughout the engines' useful life. In
recognition that emissions performance will degrade over time,
manufacturers generally design their engines to perform significantly
better than the standards when first sold to ensure that the emissions
are below the standard throughout useful life even as the emissions
controls deteriorate. As discussed in this section and in Chapter 3 of
the RIA and shown in Table III-12 and Table III-13, some manufactures
have submitted certification data with zero emissions (with rounding),
which results in a margin at 100 percent of the FEL, while other
manufacturers have margin that is less than 25 percent of the FEL.
To assess the feasibility of the final MY 2027 standards for Light,
Medium, and Heavy HDE at the corresponding final useful lives, EPA took
into consideration and evaluated the data from the EPA Stage 3 engine
as well as other available data and comments received on the proposed
standards. See section 3 of the Response to Comment document for
further information on the comments received and EPA's detailed
response.
[[Page 4341]]
As discussed in Section III.B.2, the EPA Stage 3 engine includes
improvements beyond the CARB Stage 3 engine, namely replacing the zone-
coated catalyzed soot filter with a separate DOC and DPF and improving
the mixing of the DEF with exhaust for the downstream SCR catalyst.
These improvements lowered the emissions on the SET, FTP, and LLC below
what was measured with the CARB Stage 3 engine. The emissions for the
EPA Stage 3 engine on the SET, FTP, and LLC aged to an equivalent of
435,000, 600,000 and 800,000 miles are shown in Table III-7, Table III-
8, and Table III-9. To account for the IRAF for both particulate matter
and sulfur on the aftertreatment system, we assessed and determined it
was appropriate to rely on an analysis by SwRI that is summarized in
Chapter 3 of the RIA. In this analysis SwRI determined that IRAF
NOX emissions were at 2 mg/hp-hr for both the SET and FTP
cycles and 5 mg/hp-hr for the LLC. To account for the crankcase
emissions, we assessed and determined it was appropriate to rely on an
analysis by SwRI that is summarized in Chapter 3 of the RIA. In this
analysis, SwRI determined that the NOX emissions from the
crankcase were at 6 mg/hp-hr for the LLC, FTP, and SET cycles.
To determine whether or how to account for the effects of test
procedure variability, emissions performance of other ratings in an
engine family, production and engine variability, fuel and DEF quality,
sulfur, soot and ash levels on the aftertreatment, aftertreatment aging
due to severe-service operation, and aftertreatment packaging--and
given the low level of the standards under consideration--EPA further
assessed two potential approaches after taking into consideration
comments received. The first approach considered was assigning standard
deviation and offsets to each of these effects and then combining them
using a mathematical method similar to what one commenter presented in
their comments to the NPRM.\270\ The second approach considered was
defining the margin as a percentage of the standards, similar to
assertions by two commenters. We considered both of these approaches,
the comments and supporting information submitted, historical
approaches by EPA to compliance margin in previous heavy-duty criteria
pollutant standards rules, and the data collected from the EPA Stage 3
engine and other available data, to determine the numeric level of each
standard over the corresponding useful life that is technically
feasible.
---------------------------------------------------------------------------
\270\ See RIA Chapter 3 for the details on this analysis.
---------------------------------------------------------------------------
For the first approach, we determined that a minimum of 15 mg/hp-hr
of margin between an emission standard and the NOX emissions
of the EPA Stage 3 engine for each of the duty cycles was
appropriate.\271\ For the second approach, we first assessed the
average emissions rates from the EPA Stage 3 engine at the respective
aged miles. For Light HDEs, we looked at the data at the equivalent of
435,000 miles. For the Medium and Heavy HDEs standards the interpolated
emissions performance at 650,000 miles was determined from the tests at
the equivalent of 600,000 and 800,000 miles, which is shown in Table
III-10.\272\ Second, the average emissions values were then adjusted to
account for the IRAF and crankcase emissions from the EPA Stage 3
engine. Third, we divided the adjusted emissions values by 0.55 to
calculate an emission standard that would provide 45 percent margin to
the standard. We determined it would be appropriate to apply a 45
percent margin in this case after evaluating the margin in engines that
meet the current standards as outlined in RIA chapter 3 and in CARB's
comment to the NPRM and considering the level of the standards in this
final rule. Our determination is based on our analysis that the
certification data from engines meeting today's standards shows that
more than 80 percent of engine families are certified with less than 45
percent compliance margin. For Light HDEs, we took the resulting values
from the third step of our approach and rounded them. EPA then also
checked that each of these values for each of the duty cycles
(resulting from the second approach) provided a minimum of 15 mg/hp-hr
of margin between those values and the NOX emissions of the
EPA Stage 3 engine (consistent with the first approach). For Light
HDEs, we determined those resulting values were appropriate final
numeric emission standards (as specified in Preamble Section III.B.2).
The last step of checking that the Light HDE standards provide a
minimum of 15 mg/hp-hr of NOX margin was to ensure that the
margin determined from the percent of the standard (the second approach
to margin) also provided the margin that we determined under the first
approach to margin. For Light HDEs, given the level of the final
standards and the length of the final useful life mileages, we
determined that this approach to margin was appropriate for both
certification and in-use testing of engines.
---------------------------------------------------------------------------
\271\ See RIA Chapter 3 for the details on how the margin of 15
mg/hp-hr was defined.
\272\ See RIA Chapter 3.1.1.2 for additional information on why
each aging test point was used for each primary intended service
class. We note that we received data claimed as confidential
business information from a manufacturer on August 2, 2022, and
considered that data as part of this assessment to use the EPA Stage
3 data at the equivalent of 650,000 miles for setting the Medium HDE
standards. The data were added to the docket prior to the signing of
the final rule. See also U.S. EPA. Stakeholder Meeting Log.
December, 2022.
---------------------------------------------------------------------------
Given the very long useful life mileages for Heavy HDE and greater
amounts of certain aging mechanisms over the long useful life periods
of Medium HDE, we determined that a different application of
considering these two approaches to margin was appropriate. The in-use
standards of Medium and Heavy HDEs were determined using the second
approach for determining margin. The certification standards where then
determined by subtracting the margin from the first approach (15 mg/hp-
hr) from the in-use standards.
Separating the standards from the level that applies for in-use
testing was appropriate because we recognize that laboratory aging of
the engine doesn't fully capture all the sources of deterioration of
the aftertreatment that can occur once the engine enters the real-world
and those uncertainties would be most difficult for these engine
classes at the level of the final standards and the final useful life
mileages. Some of these effects are SCR sulfation, fuel quality, DEF
quality, sensor variability, and field aging from severe duty cycles.
Thus, the last step in determining the standards for Medium and Heavy
HDE was to subtract the 15 mg/hp-hr from the rounded value that
provided 45 percent margin to the Stage 3 data. We determined each of
the resulting final duty cycle NOX standards for Medium and
Heavy HDE that must be demonstrated at the time of certification out to
350,000 and 750,000 miles, respectively, are feasible with enough
margin to account for test procedure variability. We determined this by
comparing the EPA Stage 3 emissions results at 800,000 miles (Table
III-9) after adjusting for IRAF and crankcase emissions to each of the
NOX standards in Section III.B.2. The EPA Stage 3
NOX emissions results at 800,000 miles adjusted for IRAF and
crankcase emissions are 26 mg/hp-hr for the SET, 33 mg/hp-hr for the
FTP, and 33 mg/hp-hr for the LLC. For any in-use testing of Medium and
Heavy HDEs, a 15 mg/hp-hr compliance allowance is added to the
applicable standard, in consideration of the other sources of
variability and deterioration of the aftertreatment that can occur once
the engine enters the real world.
[[Page 4342]]
As explained in the proposal, our technology cost analysis included
an increased SCR catalyst volume from what was used on the EPA and CARB
Stage 3 engines. By increasing the SCR catalyst volume, the
NOX reduction performance of the aftertreatment system
should deteriorate slower than what was demonstrated with the EPA Stage
3 engine. The increase in total SCR catalyst volume relative to the EPA
and CARB Stage 3 SCR was approximately 23.8 percent. We believe this
further supports our conclusion that the final standards are achievable
in MY 2027, including for the final useful life of 650,000 miles for
Heavy HDEs. In addition to NOX, the final HC and CO
standards are feasible for CI engines on all three cycles. This is
shown in Table III-10, where the demonstrated HC and CO emission
results are below the final standards discussed in Section III.B.2. The
final standard for PM of 5 mg/hp-hr for the SET, FTP, and LLC continue
to be feasible with the additional technology and control strategies
needed to meet the final NOX standards, as seen by the PM
emissions results in Table III-10. As discussed in Section III.B.2,
taking into account measurement variability of the PM measurement test
procedure, we believe PM emissions from current diesel engines are at
the lowest feasible level for standards starting in MY 2027.
Table III-7--Stage 3 Engine Emissions at 435,000 Mile Equivalent Test Point Without Adjustments for IRAF or Crankcase Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
NOX (mg/hp-hr) NMHC (nonmethane CO2 (g/hp-hr) N2O (g/hp-hr)
Duty cycle PM (mg/hp-hr) hydrocarbon) (mg/hp-hr) CO (g/hp-hr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
SET \a\................................... 17 1 1 0.030 455 0.024
FTP....................................... 20 2 12 0.141 514 0.076
LLC....................................... 29 3 35 0.245 617 0.132
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Using the weighting factors in our finalized test procedures (40 CFR 1036.510).
Table III-8--Stage 3 Engine Emissions at 600,000 Mile Equivalent Test Point Without Adjustments for IRAF or
Crankcase Emissions
----------------------------------------------------------------------------------------------------------------
NOX (mg/
Duty cycle hp-hr) PM (mg/hp- NMHC (mg/ CO (g/hp- CO2 (g/hp- N2O (g/hp-
hr) hp-hr) hr) hr) hr)
----------------------------------------------------------------------------------------------------------------
SET \a\....................................... 24 1 1 0.015 460 0.030
FTP........................................... 27 1 9 0.144 519 0.058
LLC........................................... 33 4 16 0.153 623 0.064
----------------------------------------------------------------------------------------------------------------
\a\ Using the weighting factors in our finalized test procedures (40 CFR 1036.510).
Table III-9--Stage 3 Engine Emissions at 800,000 Mile Equivalent Test Point Without Adjustments for IRAF or
Crankcase Emissions
----------------------------------------------------------------------------------------------------------------
NOX (mg/
Duty cycle hp-hr) PM (mg/hp- NMHC (mg/ CO (g/hp- CO2 (g/hp- N2O (g/hp-
hr) hp-hr) hr) hr) hr)
----------------------------------------------------------------------------------------------------------------
SET \a\....................................... 30 2 1 0.023 458 0.028
FTP........................................... 37 1 14 0.149 520 0.092
LLC........................................... 34 1 40 0.205 629 0.125
----------------------------------------------------------------------------------------------------------------
\a\ Using the weighting factors in our finalized test procedures (40 CFR 1036.510).
Table III-10--Stage 3 Engine Emissions at Interpolated at 650,000 Mile Equivalent Without Adjustments for IRAF
or Crankcase Emissions
----------------------------------------------------------------------------------------------------------------
NOX (mg/
Duty cycle hp-hr) PM (mg/hp- NMHC (mg/ CO (g/hp- CO2 (g/hp- N2O (g/hp-
hr) hp-hr) hr) hr) hr)
----------------------------------------------------------------------------------------------------------------
SET \a\....................................... 26 1 1 0.017 460 0.030
FTP........................................... 30 1 10 0.145 519 0.067
LLC........................................... 33 3 22 0.166 625 0.079
----------------------------------------------------------------------------------------------------------------
\a\ Using the weighting factors in our finalized test procedures (40 CFR 1036.510).
In addition to evaluating the feasibility of the new criteria
pollutant standards, we also evaluated how CO2 was impacted
on the CARB Stage 3 engine (which is the same engine that was used for
EPA's Stage 3 engine with modifications to the aftertreatment system
and engine calibration to lower NOX emissions). We did this
by evaluating how CO2 emissions changed from the base engine
over the SET, FTP, and LLC, as well as the fuel mapping test procedures
defined in 40 CFR 1036.535 and 1036.540. For all three cycles the CARB
Stage 3 engine emitted CO2 with no measurable difference
compared to the base 2017 Cummins X15 engine. Specifically, we compared
the CARB Stage 3 engine including the 0-hour (degreened) aftertreatment
with the 2017 Cummins X15 engine including degreened aftertreatment and
found the percent reduction in CO2 was
[[Page 4343]]
0 percent for the SET, 1 percent for the FTP, and 1 percent for the
LLC.\273\
---------------------------------------------------------------------------
\273\ See Chapter 3 of the RIA for the CO2 emissions
of the 2017 Cummins X15 engine and the CARB Stage 3 engine.
---------------------------------------------------------------------------
We note that while the data from the EPA Stage 3 engine (the same
engine as the CARB Stage 3 engine but after SwRI made changes to the
thermal management strategies) at the equivalent age of 435,000 miles
showed an increase in CO2 emissions for the SET, FTP, and
LLC of 0.6, 0.7 and 1.3 percent respectively, which resulted in the
CO2 emissions for the EPA Stage 3 engine being higher than
the 2017 Cummins X15 engine, this is not directly comparable because
the baseline 2017 Cummins X15 aftertreatment had not been aged to an
equivalent of 435,000 miles.\274\ As discussed in Chapter 3 of the RIA,
aging the EPA Stage 3 engine included exposing the aftertreatment to
ash, that increased the back pressure on the engine, which contributed
to the increase in CO2 emissions from the EPA Stage 3
engine. We would expect the same increase in backpressure and in
CO2 emissions from the 2017 Cummins X15 engine if the
aftertreatment of the 2017 Cummins X15 engine was aged to an equivalent
of 435,000 miles.
---------------------------------------------------------------------------
\274\ As part of the agency's diesel demonstration program, we
didn't age the aftertreatment of the base 2017 Cummins X15 engine
since the focus of this program was to demonstrate emissions
performance of future technologies and due to resource constraints.
Thus, there isn't data directly comparable to the baseline engine at
each aging step.
---------------------------------------------------------------------------
To evaluate how the technology on the CARB Stage 3 engine compares
to the 2017 Cummins X15 engine with respect to the HD GHG Phase 2
vehicle CO2 standards, both engines were tested on the fuel
mapping test procedures defined in 40 CFR 1036.535 and 1036.540. These
test procedures define how to collect the fuel consumption data from
the engine for use in GEM. For these tests the CARB Stage 3 engine was
tested with the development aged aftertreatment.\275\ The fuel maps
from these tests were run in GEM and the results from this analysis
showed that the EPA and CARB Stage 3 engine emitted CO2 at
the same rate as the 2017 Cummins X15 engine. The details of this
analysis are described in Chapter 3.1 of the RIA.
---------------------------------------------------------------------------
\275\ The CARB Stage 3 0-hour (degreened) aftertreatment could
not be used for these tests, because it had already been aged past
the 0-hour point when these tests were conducted.
---------------------------------------------------------------------------
The technologies included in the EPA Stage 3 engine were selected
to both demonstrate the lowest criteria pollutant emissions and have a
negligible effect on GHG emissions. Manufactures may choose to use
other technologies to meet the final standards, but manufacturers will
still also need to comply with the GHG standards that apply under HD
GHG Phase 2. We have, therefore, not projected an increase in GHG
emissions resulting from compliance with the final standards.
---------------------------------------------------------------------------
\276\ See RIA Chapter 3 for the details of the cost for the
aftertreatment and CDA, which are the drivers for why the
incremental direct manufacturing cost is lowest for Medium HDE.
\277\ See Table III-3 for the final useful life values and
Section IV.B.1 for the final emissions warranty periods.
---------------------------------------------------------------------------
Table III-11 summarizes the incremental direct manufacturing costs
for the final standards, from the baseline costs shown in Table III-15.
These values include aftertreatment system, closed crankcase, and CDA
costs. As discussed in Chapter 7 of the RIA, the direct manufacturing
costs include the technology costs plus some costs to improve the
durability of the technology through regulatory useful life. The
details of this analysis can be found in Chapters 3 and 7 of the
RIA.\276\ The cost of the final standards and useful life periods are
further accounted for in the indirect costs as discussed in Chapter 7
of the RIA.\277\
Table III-11--Incremental Direct Manufacturing Cost of Final Standards
for the Aftertreatment, Closed Crankcase, and CDA Technology
[2017 $]
------------------------------------------------------------------------
Medium
Light HDE HDE Heavy HDE Urban bus
------------------------------------------------------------------------
$1,957................................. $1,817 $2,316 $1,850
------------------------------------------------------------------------
b. Baseline Emissions and Cost
The basis for our baseline technology assessment is the data
provided by manufacturers in the heavy-duty in-use testing program.
This data encompasses in-use operation from nearly 300 Light HDE,
Medium HDE, and Heavy HDE vehicles. Chapter 5 of the RIA describes how
the data was used to update the MOVES model emissions rates for HD
diesel engines. Chapter 3 of the RIA summarizes the in-use emissions
performance of these engines.
We also evaluated the certification data submitted to the agency.
The data includes test results adjusted for IRAF and FEL that includes
adjustments for deterioration and margin. The certification data,
summarized in Table III-12 and Table III-13, shows that manufacturers
vary in their approach to how much margin is built into the FEL. Some
manufactures have submitted certification data with zero emissions
(with rounding), which results in a margin at 100 percent of the FEL,
while other manufacturers have margin that is less than 25 percent of
the FEL.
Table III-12--Summary of Certification Data for FTP Cycle
----------------------------------------------------------------------------------------------------------------
NOX (g/hp- PM (g/hp- NMHC (g/ CO (g/hp- N2O (g/hp-
hr) hr) hp-hr) hr) hr)
----------------------------------------------------------------------------------------------------------------
Average.................................................. 0.13 0.00 0.01 0.18 0.07
Minimum.................................................. 0.05 0.00 0.00 0.00 0.04
Maximum.................................................. 0.18 0.00 0.04 1.10 0.11
----------------------------------------------------------------------------------------------------------------
Table III-13--Summary of Certification Data for SET Cycle
----------------------------------------------------------------------------------------------------------------
NOX (g/hp- PM (g/hp- NMHC (g/ CO (g/hp- N2O (g/hp-
hr) hr) hp-hr) hr) hr)
----------------------------------------------------------------------------------------------------------------
Average.................................................. 0.11 0.00 0.01 0.00 0.06
Minimum.................................................. 0.00 0.00 0.00 0.00 0.00
Maximum.................................................. 0.18 0.00 0.04 0.20 0.11
----------------------------------------------------------------------------------------------------------------
[[Page 4344]]
In addition to analyzing the on-cycle certification data submitted
by manufacturers, we tested three modern HD diesel engines on an engine
dynamometer and analyzed the data. These engines were a 2018 Cummins
B6.7, 2018 Detroit DD15 and 2018 Navistar A26. These engines were
tested on cycles that range in power demand from the creep mode of the
Heavy Heavy-Duty Diesel Truck (HHDDT) schedule to the HD SET cycle
defined in 40 CFR 1036.510. Table III-14 summarizes the range of
results from these engines on the SET, FTP, and LLC. As described in
Chapter 3 of the RIA, the emissions of current production heavy-duty
engines vary from engine to engine but the largest difference in NOX
between engines is seen on the LLC.
Table III-14--Range of NOX Emissions From MY2018 Heavy-Duty Diesel Engines
----------------------------------------------------------------------------------------------------------------
SET in 40 CFR SET in 40 CFR
NOX (g/hp-hr) 86.1333 1036.510 FTP composite LLC
----------------------------------------------------------------------------------------------------------------
Minimum......................................... 0.01 0.01 0.10 0.35
Maximum......................................... 0.12 0.05 0.15 0.81
Average......................................... 0.06 0.03 0.13 0.59
----------------------------------------------------------------------------------------------------------------
Table III-15 summarizes the baseline sales-weighted total
aftertreatment cost of Light HDEs, Medium HDEs, Heavy HDEs and urban
bus engines. The details of this analysis can be found in Chapters 3
and 7 of the RIA.
Table III-15--Baseline Direct Manufacturing Aftertreatment Cost
[2017 $]
----------------------------------------------------------------------------------------------------------------
Light HDE Medium HDE Heavy HDE Urban bus
----------------------------------------------------------------------------------------------------------------
$2,585....................................................... $2,536 $3,761 $2,613
----------------------------------------------------------------------------------------------------------------
C. Summary of Compression-Ignition Off-Cycle Standards and Off-Cycle
Test Procedures
In this Section 0, we describe the final off-cycle standards and
test procedures that will apply for model year 2027 and later heavy-
duty compression-ignition engines. The final off-cycle standards and
test procedures cover the range of operation included in the duty cycle
test procedures and operation that is outside of the duty cycle test
procedures for each regulated pollutant (NOX, HC, CO, and
PM). As described in Section III.C.1, our current not-to-exceed (NTE)
test procedures were not designed to capture and control low-load
operation. In contrast to the current NTE approach that evaluates
engine operation within the NTE zone and excludes operation out of the
NTE zone, we are finalizing a moving average window (MAW) approach that
divides engine operation into two categories (or ``bins'') based on the
time-weighted average engine power of each MAW of engine data. See
Section III.C.2 for a discussion of the derivation of the final off-
cycle standards for each bin. For bin 1, the NOX emission
standard is 10.0 g/hr. The final off-cycle standards for bin 2 are
shown in Table III-16.
Table III-16--Final Off-Cycle Bin 2 Standards for Light HDE, Medium HDE, and Heavy HDE
----------------------------------------------------------------------------------------------------------------
NOX (mg/hp-hr) HC (mg/hp-hr) PM (mg/hp-hr) CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
58 \a\....................................................... 120 7.5 9
----------------------------------------------------------------------------------------------------------------
\a\ An interim NOX compliance allowance of 15 mg/hp-hr applies for any in-use testing of Medium HDE and Heavy
HDE. Manufacturers will add the compliance allowance to the NOX standard that applies for each duty cycle and
for off-cycle testing, with both field testing and laboratory testing.
The proposed rule provided an extensive discussion of the rationale
and information supporting the proposed off-cycle standards (87 FR
17472, March 28, 2022). Chapters 2 and 3 of the RIA include additional
information including background on applicable test procedures and the
full feasibility analysis for compression-ignition engines. See also
section 11.3 of the Response to Comments for a detailed discussion of
the comments and how they have informed this final rule.
1. Existing NTE Standards and Need for Changes to Off-Cycle Test
Procedures
Heavy-duty CI engines are currently subject to Not-To-Exceed (NTE)
standards that are not limited to specific test cycles, which means
they can be evaluated not only in the laboratory but also in-use. NTE
standards and test procedures are generally referred to as ``off-
cycle'' standards and test procedures. These off-cycle emission
standards are 1.5 (1.25 for CO) times the laboratory certification
standard for NOX, HC, PM and CO and can be found in 40 CFR
86.007-11.\278\ NTE standards have been successful in broadening the
types of operation for which manufacturers design their emission
controls to remain effective, including steady cruise operation.
However, there remains a significant proportion of vehicle operation
not covered by NTE standards.
---------------------------------------------------------------------------
\278\ As noted in Section IV.G, manufacturers choosing to
participate in the existing or final averaging, banking, and trading
program agree to meet the family emissions limit (FEL) declared
whenever the engine is tested over the applicable duty- or off-cycle
test procedure. The FELs serves as the emission standard for
compliance testing instead of the standards specified in 40 CFR
86.007-11 or 40 CFR 1036.104(a); thus, the existing off-cycle
standards are 1.5 (1.25 for CO) times the FEL for manufacturers who
choose to participate in ABT.
---------------------------------------------------------------------------
[[Page 4345]]
Compliance with an NTE standard is based on emission test data
(whether collected in a laboratory or in use) analyzed pursuant to 40
CFR 86.1370 to identify NTE events, which are intervals of at least 30
seconds when engine speeds and loads remain in the NTE control area or
``NTE zone''. The NTE zone excludes engine operation that falls below
certain torque, power, and speed values.\279\ The NTE procedure also
excludes engine operation that occurs in certain ambient conditions
(i.e., high altitudes, high intake manifold humidity), or when
aftertreatment temperatures are below 250 [deg]C. Collected data is
considered a valid NTE event if it occurs within the NTE zone, lasts at
least 30 seconds, and does not occur during any of the exclusion
conditions (ambient conditions or aftertreatment temperature).
---------------------------------------------------------------------------
\279\ Specifically, engine operations are excluded if they fall
below 30 percent of maximum torque, 30 percent of maximum power, or
15 percent of the European Stationary Cycle speed.
---------------------------------------------------------------------------
The purpose of the NTE test procedure is to measure emissions
during engine operation conditions that could reasonably be expected to
occur during normal vehicle use; however, only data in a valid NTE
event is then compared to the NTE emission standard. Our analysis of
existing heavy-duty in-use vehicle test data indicates that less than
ten percent of a typical time-based dataset are part of valid NTE
events, and hence subject to the NTE standards; the remaining test data
are excluded from consideration. We also found that emissions are high
during many of the excluded periods of operation, such as when the
aftertreatment temperature drops below the 250 [deg]C exclusion
criterion. Our review of in-use data indicates that extended time at
low load and idle operation results in low aftertreatment temperatures,
which in turn lead to diesel engine SCR-based emission control systems
not functioning over a significant fraction of real-world
operation.\280\ \281\ \282\ Test data collected as part of EPA's
manufacturer-run in-use testing program indicate that low-load
operation could account for greater than 50 percent of the
NOX emissions from a vehicle over a given workday.\283\
---------------------------------------------------------------------------
\280\ Hamady, Fakhri, Duncan, Alan. ``A Comprehensive Study of
Manufacturers In-Use Testing Data Collected from Heavy-Duty Diesel
Engines Using Portable Emissions Measurement System (PEMS)''. 29th
CRC Real World Emissions Workshop, March 10-13, 2019.
\281\ Sandhu, Gurdas, et al. ``Identifying Areas of High
NOX Operation in Heavy-Duty Vehicles''. 28th CRC Real-
World Emissions Workshop, March 18-21, 2018.
\282\ Sandhu, Gurdas, et al. ``In-Use Emission Rates for MY
2010+ Heavy-Duty Diesel Vehicles''. 27th CRC Real-World Emissions
Workshop, March 26-29, 2017.
\283\ Sandhu, Gurdas, et al. ``Identifying Areas of High
NOX Operation in Heavy-Duty Vehicles''. 28th CRC Real-
World Emissions Workshop, March 18-21, 2018.
---------------------------------------------------------------------------
For example, 96 percent of tests in response to 2014, 2015, and
2016 EPA in-use testing orders passed with NOX emissions for
valid NTE events well below the 0.3 g/hp-hr NOX NTE
standard. When we used the same data to calculate NOX
emissions over all operation measured, not limited to valid NTE events,
the NOX emissions were more than double those within the
valid NTE events (0.5 g/hp-hr).\284\ The results were even higher when
we analyzed the data to consider only NOX emissions that
occur during low load events.
---------------------------------------------------------------------------
\284\ Hamady, Fakhri, Duncan, Alan. ``A Comprehensive Study of
Manufacturers In-Use Testing Data Collected from Heavy-Duty Diesel
Engines Using Portable Emissions Measurement System (PEMS)''. 29th
CRC Real World Emissions Workshop, March 10-13, 2019.
---------------------------------------------------------------------------
EPA and others have compared the performance of US-certified
engines and those certified to European Union emission standards and
concluded that the European engines' NOX emissions are lower
in low-load conditions, but comparable to US-certified engines subject
to MY 2010 standards under city and highway operation.\285\ This
suggests that manufacturers are responding to the European
certification standards by designing their emission controls to perform
well under low-load operations, as well as highway operations.
---------------------------------------------------------------------------
\285\ Rodriguez, F.; Posada, F. ``Future Heavy-Duty Emission
Standards An Opportunity for International Harmonization''. The
International Council on Clean Transportation. November 2019.
Available online: https://theicct.org/sites/default/files/publications/Future%20_HDV_standards_opportunity_20191125.pdf.
---------------------------------------------------------------------------
The European Union ``Euro VI'' emission standards for heavy-duty
engines require manufacturers to check for ``in-service conformity'' by
operating their engines over a mix of urban, rural, and motorway
driving on prescribed routes using portable emission measurement system
(PEMS) equipment to measure emissions.\286\ \287\ Compliance is
determined using a work-based windows approach where emissions data are
evaluated over segments or ``windows.'' A window consists of
consecutive 1 Hz data points that are summed until the engine performs
an amount of work equivalent to the European transient engine test
cycle (World Harmonized Transient Cycle).
---------------------------------------------------------------------------
\286\ COMMISSION REGULATION (EU) No 582/2011, May 25, 2011.
Available online: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:02011R0582-20180118&from=EN.
\287\ COMMISSION REGULATION (EU) 2018/932, June 29, 2018.
Available online: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32018R0932&from=EN.
---------------------------------------------------------------------------
EPA is finalizing new off-cycle test procedures similar to the
European Euro VI in-service conformity program, with key distinctions
that build upon the Euro VI approach, as discussed in the following
section. This new approach will require manufacturers to account for a
relatively larger proportion of engine operation and thereby further
ensure that real-world emissions meet the off-cycle standards.
2. Off-Cycle Standards and Test Procedures
We are replacing the NTE test procedures and standards (for
NOX, PM, HC and CO) for model year 2027 and later engines.
Under the final new off-cycle standards and test procedures, engine
operation and emissions test data must be assessed in test intervals
that consist of 300-second moving average windows (MAWs) of continuous
engine operation. Our evaluation accounts for our current understanding
that shorter windows are more sensitive to measurement variability and
longer windows make it difficult to distinguish between duty cycles. In
contrast to the current NTE approach that divides engine operation into
two categories (in the NTE zone and out of the NTE zone), this approach
will divide engine operation into two categories (or ``bins'') based on
the time-weighted average engine power of each MAW of engine data, with
some limited exclusions from the two bins, as described in more detail
in the following discussion.
In the NPRM, we requested comment on the proposed off-cycle
standards and test procedures, including the 300 second length of the
window. We first note that commenters broadly agree that the current
NTE methodology should be revised, and that a MAW structure is
preferable for off-cycle standards. Some commenters were concerned that
individual seconds of data would be ``smeared,'' with the same 1-Hz
data appearing in both bins as the 300 second windows are placed in the
appropriate bin. We are finalizing the window length that we proposed,
as the 300 second length provides an adequate averaging time to smooth
any anomalous emission events and we anticipate that the final bin
structure described in Section III.C.2.i. should also help address
these concerns. See Response to Comments Section 11.1 through 11.3 for
further details on these comments and EPA's response to these comments.
Although this program has similarities to the European Euro VI
approach, we are not limiting our off-
[[Page 4346]]
cycle standards and test procedures to operation on prescribed routes.
Our current NTE program is not limited to prescribed routes, and we
would consider it an unnecessary step backward to change that aspect of
the procedure.
In Section IV.G, we discuss the final rule updates to the ABT
program to account for these new off-cycle standards.
i. Moving Average Window Operation Bins
The final bin structure includes two bins of operation that
represent two different domains of emission performance. Bin 1
represents extended idle operation and other very low load operation
where engine exhaust temperatures may drop below the optimal
temperature for aftertreatment function. Bin 2 represents higher power
operation including much of the operation currently covered by the NTE.
Operation in bin 2 naturally involves higher exhaust temperatures and
catalyst efficiencies. Because this approach divides 300 second windows
into bins based on time-averaged engine power of the window, any of the
bins could include some idle or high-power operation. Like the duty
cycle standards, we believe more than a single standard is needed to
apply to the entire range of operation that heavy-duty engines
experience. A numerical standard that is technologically feasible under
worst case conditions such as idle would necessarily be much higher
than the levels that are achievable when the aftertreatment is
functioning optimally. Section III.C.2.iii includes the final numeric
off-cycle standards.
Given the challenges of measuring engine power directly in-use, we
are using the CO2 emission rate (grams per second) as a
surrogate for engine power in defining the bins for an engine. We are
further normalizing CO2 emission rates relative to the
nominal maximum CO2 rate of the engine. So, if an engine
with a maximum CO2 emission rate of 50 g/sec was found to be
emitting CO2 at a rate of 10 g/sec, its normalized
CO2 emission rate would be 20 percent. The maximum
CO2 rate is defined as the engine's rated maximum power
multiplied by the engine's CO2 family certification level
(FCL) for the FTP certification cycle.
In the proposal, we requested comment on whether the maximum
CO2 mass emission rate should instead be determined from the
steady-state fuel mapping procedure in 40 CFR 1036.535 or the torque
mapping procedure defined in 40 CFR 1065.510. After considering
comments, EPA is finalizing the use of the CO2 emission rate
as a surrogate for engine power with the proposed approach to
determining the maximum CO2 mass emission rate. We have two
main reasons for finalizing the determination of maximum CO2
mass emission rate as proposed. First, the FTP FCL and maximum engine
power are already reported to the EPA, so no new requirements are
needed under the finalized approach. Second, our assessment of the
finalized approach has shown that this approach for the determination
of maximum CO2 mass emission rate matches well with the
other options we requested comment on. EPA believes that using the
CO2 emission rate will automatically account for additional
fuel usage not directly used for driveshaft torque and minimizes
concerns about the accuracy and data alignment in the use of broadcast
torque. EPA acknowledges that there is some small variation in
efficiency, and thus CO2 emissions rates, among engines.
However, the test procedure accounts for improvements to the engine
efficiency by using the FTP FCL to convert CO2 specific
NOX to work specific NOX. This is because the FTP
FCL captures the efficiency of the engine over a wide range of
operation, from cold start, idle and steady-state higher power
operation. Furthermore, the FTP FCL can also capture the CO2
improvements from hybrid technology when the powertrain test option
described in preamble Section III.B.2.v is utilized.
The bins are defined as follows:
Bin 1: 300 second windows with normalized average
CO2 rate <=6 percent.
Bin 2: 300 second windows with normalized average
CO2 rate >6 percent.
The bin cut point of six percent is near the average power of the
low-load cycle. In the NPRM, we proposed a three-bin structure and
requested comment on the proposed number of bins and the value of the
cut point(s). After considering comments, EPA agrees with commenters to
the extent the commenters recommend combining the proposed bins 2 and 3
into a single ``non-idle'' bin 2. Results from the EPA Stage 3 real
world testing indicate that emissions in bins 2 and 3 (expressed as
emissions/normalized CO2) are substantially similar,
minimizing the advantage of separating these modes of operation. See
Response to Comments Section 11.1 for further details on these comments
and EPA's response to these comments.
To ensure that there is adequate data in each of the bins to
compare to the off-cycle standards, the final requirements specify that
there must be a minimum of 2,400 moving average windows in bin 1 and
10,000 moving average windows in bin 2. In the NPRM, we proposed a
minimum of 2,400 windows for all bins and requested comment on the
appropriate minimum number of windows required to sufficiently reduce
variability in the results while not requiring an unnecessary number of
shift days to be tested to meet the requirement. EPA received comments
both supporting the proposed 2,400 window minimum and supporting an
increase to 10,000 windows total for the non-idle bins (now a single
bin 2 in this final rule). After considering comments, we believe
requiring a minimum of 10,000 windows in final bin 2 to define a valid
test is appropriate. Analysis of data from the EPA Stage 3 off-cycle
test data has shown that emissions are stable after 6,000 windows of
data at moderate temperatures but NOX emissions under low
ambient temperatures need closer to 10,000 windows to be stable. EPA
believes the larger number of required windows will better characterize
the emissions performance of the engine.
If during the first shift day any of the bins do not include at
least the minimum number of windows, then the engine will need to be
tested for additional day(s) until the minimum requirement is met.
Additionally, the engine can be idled at the end of the shift day to
meet the minimum window count requirement for the idle bin. This is to
ensure that even for duty cycles that do not include significant idle
operation the minimum window count requirement for the idle bin can be
met without testing additional days.
We received comments on the timing and duration of the optional
end-of-day idle. After considering comments, the final requirements
specify that the ability to add idle time is restricted to the end of
the shift day, and manufacturers may extend this end-of-day idle period
to be as long as they choose. Additional idle in the middle of the
shift day is contrary to the intent of real-world testing, and the end
of the shift day is the only realistic time to add windows. Since idle
times of varying lengths are encountered in real-world operation, we do
not think that requiring a specific length of idle time would
necessarily make the resulting data set more representative.
As described further in section III.C.2.ii, after consideration of
comment, EPA is including requirements in 40 CFR 1036.420 that specify
that during the end-of-day idle period, when testing vehicles with
automated engine shutdown features, manufacturers will be required to
override the automated shutdown feature where possible. This will
ensure
[[Page 4347]]
that the test data will contain at least 2,400 windows in the idle bin,
which otherwise would be unobtainable. For automated shutdown features
that cannot be overridden, the manufacturer may populate the bin with
zero emission values for idle until exactly 2,400 windows are achieved.
ii. Off-Cycle Test Procedures
The final off-cycle test procedures include measuring off-cycle
emissions using the existing test procedures that specify measurement
equipment and the process of measuring emissions during testing in 40
CFR part 1065. Part 1036, subpart E contains the process for recruiting
test vehicles, how to test over the shift day, how to evaluate the
data, what constitutes a valid test, and how to determine if an engine
family passes. Measurements may use either the general laboratory test
procedures or the field-testing procedures in 40 CFR part 1065, subpart
J. However, we are finalizing special calculations for bin 2 in 40 CFR
1036.530 that will supersede the brake-specific emission calculations
in 40 CFR part 1065. The test procedures require second-by-second
measurement of the following parameters:
Molar concentration of CO2 (ppm)
Molar concentration of NOX (ppm)
Molar concentration of HC (ppm)
Molar concentration of CO (ppm)
Concentration of PM (g/m\3\)
Exhaust flow rate (m\3\/s)
Mass emissions of CO2 and each regulated pollutant are
separately determined for each 300-second window and are binned based
on the normalized CO2 rate for each window.
Additionally, EPA agrees with commenters that the maximum allowable
engine coolant temperature at the start of the day should be raised to
40 degrees Celsius and we are finalizing this change in 40 CFR
1036.530. In the NPRM, we proposed 30 [deg]C which is 86 [deg]F. It is
possible that ambient temperatures in some regions of the United States
won't drop below this overnight. We are therefore finalizing 40 [deg]C
which is 104 [deg]F as this should ensure that high overnight ambient
temperatures do not prevent a manufacturer from testing a vehicle.
The standards described in Section III.C.2.iii are expressed in
units of g/hr for bin 1 and mg/hp-hr for bin 2. However, unlike most of
our exhaust standards, the hp-hr values for the off-cycle standards do
not refer to actual brake work. Rather, they refer to nominal
equivalent work calculated proportional to the CO2 emission
rate. Thus, in 40 CFR 1036.530 the NOX emissions (``e'') in
g/hp-hr are calculated as:
[GRAPHIC] [TIFF OMITTED] TR24JA23.000
The final requirements include a limited number of exclusions (six
total) in 40 CFR 1036.530(c)(3) that exclude some data from being
subject to the off-cycle standards. The first exclusion in 40 CFR
1036.530(c)(3)(i) is for data collected during periodic PEMS zero and
span drift checks or calibrations, where the emission analyzers and/or
flow meter are not available to measure emissions during that time and
these checks/calibrations are needed to ensure the robustness of the
data.
The second exclusion in 40 CFR 1036.530(c)(3)(ii) is for data
collected anytime the engine is off during the course of the shift day,
with modifications from proposal that (1) this exclusion does not
include engine off due to automated stop-start, and (2) specific
requirements for vehicles with stop-start technology. In the NPRM, we
proposed excluding data for vehicles with stop-start technology when
the engine was off and requested comment on the appropriateness of this
exclusion. We received comment suggesting provisions for vehicles
equipped with automated stop-start technology. After considering
comments, EPA has included in the final rule requirements applicable
when testing vehicles with automatic engine shutdown (AES) and/or stop-
start technology. Under the final requirements, the manufacturer shall
disable AES and/or stop-start if it is not tamper resistant as
described in 40 CFR 1036.415(g), 1036.420(c), and 1036.530(c)(3). If
stop-start is tamper resistant, the 1-Hz emission rate for all GHG and
criteria pollutants shall be set to zero when AES and/or stop-start is
active and the engine is off, and these data are included in the normal
windowing process (i.e., the engine-off data are not treated as
exclusions). If at the end of the shift day there are not 2,400 windows
in bin 1 for a vehicle with AES and/or stop-start technology, the
manufacturer must populate the bin with additional windows with the
emission rate for each GHG and criteria pollutant set to zero to
achieve exactly 2,400 idle bin windows. This process accounts for
manufacturers who implement a start/stop mode that cannot be overridden
and applies the windowing and binning process in a way that is similar
to the process applied to a conventionally idling vehicle.
The third exclusion in 40 CFR 1036.530(c)(3)(iii) is for data
collected during infrequent regeneration events. The data collected for
the test order may not collect enough operation to properly weight the
emissions rates during an infrequent regeneration event with emissions
that occur without an infrequent regeneration event.
The fourth exclusion in 40 CFR 1036.530(c)(3)(iv) is for data
collected when ambient temperatures are below 5 [deg]C (this aspect
includes some modifications from proposal), or when ambient
temperatures are above the altitude-based value determined using
Equation 40 CFR 1036.530-1. The colder temperatures can significantly
inhibit the engine's ability to maintain aftertreatment temperature
above the minimum operating temperature of the SCR catalyst while the
higher temperature conditions at altitude can limit the mass airflow
through the engine, which can adversely affect the engine's ability to
reduce engine out NOX through the use of exhaust gas
recirculation (EGR). In addition to affecting EGR, the air-fuel ratio
of the engine can decrease under high load, which can increase exhaust
temperatures above the conditions where the SCR catalyst is most
efficient at reducing NOX. However, we also do not want to
select temperature limits that overly exclude operation, such as
setting a cold temperature limit so high that it excludes important
initial cold start operation from all tests, or a number of return to
service events. These are important operational regimes, and the MAW
protocol is intended to capture emissions over the entire operation of
the vehicle. The final rule strikes an appropriate balance between
these considerations.
In the NPRM, we proposed excluding data when ambient temperatures
were below -7 [deg]C and requested comment on the appropriateness of
this exclusion. Several comments disagreed with the proposed low
temperature exclusion level and recommended a higher
[[Page 4348]]
temperature of 20 [deg]C as well as additional exemptions for coolant
and oil temperatures, and recommended low temperature exclusion
temperatures that ranged from 20 to 70 [deg]C. After considering
comments, we adjusted the final ambient temperature exclusion to 5
[deg]C. We have additionally incorporated a temperature-based
adjustment to the final numerical NOX standards, as
described in Section III.C.iii. However, we have not incorporated
exclusions based on coolant and oil temperatures. These changes are
supported by data recently generated from testing at SwRI with the EPA
Stage 3 engine at low temperatures over the CARB Southern Route Cycle
and Low Load Cycle. This testing consisted of operation of the engine
over the duty-cycle with the test cell ambient temperature set at 5
[deg]C with air flow moving over the aftertreatment system to simulate
the airflow over the aftertreatment during over the road operation. The
results indicated that there were cold ambient air temperature effects
on aftertreatment temperature that reduced NOX reduction
efficiency, which supports that the temperature should be increased.
With these changes, our analysis, as described in section III.C, shows
that the off-cycle standards are achievable for MY 2027 and later
engines down to 5 [deg]C, taking into account the temperature-based
adjustment to the final numerical standards. We have concerns about
whether the off-cycle standards could be met below 5 [deg]C after
taking a closer look at all data regarding real world effects and based
on this we are exempting data from operation below 5 [deg]C from being
subject to the standards.
The fifth exclusion in 40 CFR 1036.530(c)(3)(v) is for data
collected where the altitude is greater than 5,500 feet above sea level
for the same reasons as for the high temperatures at altitude
exclusion.
The sixth exclusion in 40 CFR 1036.530(c)(3)(vi) is for data
collected when any approved Auxiliary Emission Control Device (AECD)
for emergency vehicles are active because the engines are allowed to
exceed the emission standards while these AECDs are active.
To reduce the influence of environmental conditions on the accuracy
and precision of the PEMS for off-cycle in-use testing, we are adding
additional changes to those proposed in requirements in 40 CFR
1065.910(b). These requirements are to minimize the influence of
temperature, electromagnetic frequency, shock, and vibration on the
emissions measurement. If the design of the PEMS or the installation of
the PEMS does not minimize the influence of these environmental
conditions, the final requirements specify that the PEMS must be
installed in an environmental chamber during the off-cycle test to
minimize these effects.
iii. Off-Cycle Standards
For NOX, we are finalizing separate standards for
distinct modes of operation. To ensure that the duty-cycle
NOX standards and the off-cycle NOX standards are
set at the same relative stringency level, the bin 1 standard is
proportional to the Voluntary Idle standard discussed in Section
III.B.2.iv, and the bin 2 standard is proportional to a weighted
combination of the LLC standard discussed in Section III.B.2.iii and
the SET standard discussed in Section III.B.2.ii. For bin 1, the
NOX emission standard for all CI primary intended service
classes is 10.0 g/hr starting in model year 2027. For PM, HC and CO we
are not setting standards for bin 1 because the emissions from these
pollutants are very small under idle conditions and idle operation is
extensively covered by the SET, FTP, and LLC duty cycles discussed in
Section III.B.2. The combined NOX bin 2 standard is weighted
at 25 percent of the LLC standard and 75 percent of the SET standard,
reflecting the nominal flow difference between the two cycles. For HC,
the bin 2 standard is also set at values proportional to a 25 percent/
75 percent weighted combination of the LLC standard and the SET
standard.\288\ For PM and CO, the SET, FTP, and LLC standards are the
same numeric value, so bin 2 is proportional to that numeric standard.
The numerical values of the off-cycle standards for bin 2 are shown in
Table III-17.
---------------------------------------------------------------------------
\288\ See Preamble Section III.B.2 for the HC standards for the
SET and LLC.
---------------------------------------------------------------------------
The final numerical off-cycle bin 1 NOX standard reflect
a conformity factor of 1.0 times the Clean Idle standard discussed in
Section III.B.2.iv. The final numerical off-cycle bin 2 standards for
all pollutants reflect a conformity factor of 1.5 times the duty-cycle
standards set for the LLC and SET cycles discussed in Section
III.B.2.ii and Section III.B.2.iii. Additionally, as discussed in
Section III.B.2, the in-use NOX off-cycle standard for
Medium and Heavy HDE reflects an additional 15 mg/hp-hr NOX
allowance above the bin 2 standard. Similar to the duty cycle
standards, the off-cycle standards were set at a level that resulted in
at least 40 percent compliance margin for the EPA Stage 3 engine. We
requested and received comments on the appropriate scaling factors or
other approaches to setting off-cycle standards. After consideration of
the comments, we believe the final numerical standards are feasible and
appropriate for certification and in-use testing. We note that the
final standards are similar, but not identical to, the options proposed
in the NPRM. As with the duty cycle standards discussed in Preamble
Section III.B, the data from the EPA Stage 3 engine supported the most
stringent numeric standards we proposed under low-load operation and
the most stringent numeric standards we proposed for MY 2027 under high
load operation. More discussion of the feasibility of these standards
can be found in the following discussion and in Section III.C.3 and
Response to Comments Section 11.3.1.
Table III-17--Off-Cycle Bin 2 Standards
----------------------------------------------------------------------------------------------------------------
NOX (mg/hp-hr) HC (mg/hp-hr) PM (mg/hp-hr) CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
58 \a\....................................................... 120 7.5 9
----------------------------------------------------------------------------------------------------------------
\a\ An interim NOX compliance allowance of 15 mg/hp-hr applies for any in-use testing of Medium HDE and Heavy
HDE. Manufacturers will add the compliance allowance to the NOX standard that applies for each duty cycle and
for off-cycle Bin 2, for both in-use field testing and laboratory testing as described in 40 CFR 1036, subpart
E. Note, the NOX compliance allowance doesn't apply to confirmatory testing described in 40 CFR 1036.235(c) or
selective enforcement audits described in 40 CFR part 1068.
In the proposal, we requested comment on the in-use test conditions
over which engines should be required to comply with the standard,
asking commentors to take into consideration any tradeoffs that broader
or narrower
[[Page 4349]]
conditions might have on the stringency of the standard we set. After
considering comments on low ambient air temperature and the available
data from the low-temperature Stage 3 testing at SwRI described in
section III.C.2.ii, we are also incorporating an adjustment to the
numerical off-cycle bin 1 and bin 2 standards for NOX as a
function of ambient air temperature below 25 [deg]C. The results
demonstrated higher NOX emissions at low temperatures,
indicating that standards should be numerically higher to account for
real-world temperature effects on the aftertreatment system. To
determine the magnitude of this adjustment, we calculated the increase
in the Stage 3 engine NOX emissions over the CARB Southern
Route Cycle at low temperature over the NOX emissions at 25
[deg]C. These values were linearly extrapolated to determine the
projected increase at 5 [deg]C versus 25 [deg]C. Table III-18 presents
the numerical value of each off-cycle bin 1 and bin 2 NOX
standard at both 25 [deg]C and 5 [deg]C.
Under the final requirements in 40 CFR 1036.104, the ambient
temperature adjustment is applied based on the average 1-Hz ambient air
temperature during the shift day for all data not excluded under 40 CFR
1036.530(c), calculated as the time-averaged temperature of all
included data points. If this average temperature is 25 [deg]C or
above, no adjustment to the standard is made. If the average
temperature is below 25 [deg]C, the applicable NOX standard
is calculated using the equations in Table 3 to paragraph (a)(3) of 40
CFR 1036.104 Table III-18 for the appropriate service class and bin.
Table III-18--Temperature Adjustments to the Off-Cycle NOX Standards
----------------------------------------------------------------------------------------------------------------
NOX NOX
standard standard
Service class Applicability Bin at 25 at 5 Applicable unit
[deg]C [deg]C
----------------------------------------------------------------------------------------------------------------
All............................... All.................. 1 10 \a\ 15 g/hr.
Light HDE......................... Certification & In- 2 58 \a\ 102 mg/hp-hr.
use.
Medium and Heavy HDE.............. Certification........ 2 58 \a\ 102 mg/hp-hr.
Medium and Heavy HDE.............. In-Use............... 2 \a\ 73 \a\ 117 mg/hp-hr.
----------------------------------------------------------------------------------------------------------------
\a\ The Bin 1 and Bin 2 ambient temperature adjustment and the NOX compliance allowance for in-use testing do
not scale with the FELFTPNOx.
3. Feasibility of the Diesel (Compression-Ignition) Off-Cycle Standards
i. Technologies
As a starting point for our determination of the appropriate
numeric levels of the off-cycle emission standards, we considered
whether manufacturers could meet the duty-cycle standard corresponding
to the type of engine operation included in a given bin,\289\ as
follows:
---------------------------------------------------------------------------
\289\ See preamble Section III.B.3 for details on EPA's
assessment of the feasibility of the duty-cycle standards.
---------------------------------------------------------------------------
Bin 1 operation is generally similar to operation at idle
and the lower speed portions of the LLC.
Bin 2 operation is generally similar to operation over the
LLC, the FTP and much of the SET.
An important question is whether the off-cycle standards would
require technology beyond what we are projecting would be necessary to
meet the duty-cycle standards. As described in this section, we do not
expect the off-cycle standards to require different technologies.
This is not to say that we expect manufacturers to be able to meet
these standards with no additional work. Rather, we project that the
off-cycle standards can be met primarily through additional effort to
calibrate the duty-cycle technologies to function properly over the
broader range of in-use conditions. We also recognize that
manufacturers can choose to include additional technology, if it
provided a less expensive or otherwise preferred option.
When we evaluated the technologies discussed in Section III.B.3.i
with emissions controls that were designed to cover a broad range of
operation, it was clear that we should set the off-cycle standards to
higher numerical values than the duty-cycle standards to take into
account the broader operations covered by the off-cycle test
procedures. Section III.C.3.ii explains how the technology and controls
performed when testing with the off-cycle test procedures over a broad
range of operation. The data presented in Section III.C.3.ii shows that
even though there are similarities in the operation between the duty
cycles (SET, FTP, and LLC) and the off-cycle bins 1 and 2, the broader
range of operation covered by the off-cycle test procedure results in a
broader range of emissions performance, which justifies setting the
numeric off-cycle standards higher than the corresponding duty cycle
standards for equivalent stringency. In addition to this, the off-cycle
test procedures and standards cover a broader range of ambient
temperature and pressure, which can also increase the emissions from
the engine as discussed in Section III.C.2.ii.
ii. Summary of Feasibility Analysis
To identify appropriate numerical levels for the off-cycle
standards, we evaluated the performance of the EPA Stage 3 engine in
the laboratory on five different cycles that were created from field
data of HD engines that cover a range of off-cycle operation. These
cycles are the CARB Southern Route Cycle, Grocery Delivery Truck Cycle,
Drayage Truck Cycle, Euro-VI ISC Cycle (EU ISC) and the Advanced
Collaborative Emissions Study (ACES) cycle. The CARB Southern Route
Cycle is predominantly highway operation with elevation changes
resulting in extended motoring sections followed by high power
operation. The Grocery Delivery Truck Cycle represents goods delivery
from regional warehouses to downtown and suburban supermarkets and
extended engine-off events characteristic of unloading events at
supermarkets. Drayage Truck Cycle includes near dock and local
operation of drayage trucks, with extended idle and creep operation.
Euro-VI ISC Cycle is modeled after Euro VI ISC route requirements with
a mix of 30 percent urban, 25 percent rural and 45 percent highway
operation. ACES Cycle is a 5-mode cycle developed as part of ACES
program. Chapter 3 of the RIA includes figures that show the engine
speed, engine torque and vehicle speed of the cycles.
The engine was initially calibrated to minimize NOX
emissions for the dynamometer duty cycles (SET, FTP, and LLC). It was
then further calibrated to achieve more optimal performance over off-
cycle operation. The test results shown in Table III-19 provide a
reasonable basis for evaluating the feasibility of controlling off-
cycle emissions to a useful life of 435,000 miles and 800,000 miles.
Additionally,
[[Page 4350]]
the engine tested did not include the SCR catalyst volume that is
included in our cost analysis and that we determined should enable
lower bin 2 NOX emissions, further supporting that the final
standards are feasible. Additionally, the 800,000 mile aged
aftertreatment was tested over the CARB Southern Route Cycle with an
ambient temperature between 2 [deg]C and 9 [deg]C (6.8 [deg]C average),
the average of which is slightly above the 5 [deg]C minimum ambient
temperature that the final requirements specify as the level below
which test data are excluded.\290\ The summary of the results is in
Chapter 3 of the RIA. For Light HDE standards, we looked at the data at
the equivalent of 435,000 miles.\291\ For the Medium and Heavy HDE
standards we looked at the data at the equivalent of 800,000
miles.\292\
---------------------------------------------------------------------------
\290\ The low ambient temperature exclusion was raised from the
proposed level of -7 [deg]C to 5 [deg]C, since engines can continue
to use EGR to reduce NOX without the use of an EGR cooler
bypass at and above 5 [deg]C. See RIA Chapter 3.1.1.2.2 for a
summary of data from the EPA Stage 3 engine with three different
idle calibrations.
\291\ See Section III.B.3.ii for an explanation on why we
determined data at the equivalent of 435,000 miles was appropriate
for determining the feasibility of the Light HDE standards.
\292\ Similar to our reasoning in Section III.B.3.ii for using
the interpolated data at the equivalent of 650,000 miles to
determine the feasibility of the duty cycle standards for Medium and
Heavy HDE, we determined the data at the equivalent of 800,000 was
appropriate for determining the feasibility of the Medium and Heavy
HDE off-cycle standards. The one difference is that emission data
was not collected at the equivalent of 600,000 miles. Therefore, we
used the data at the equivalent of 800,000 miles (rather than
assuming the emissions performance changed linearly and
interpolating the emissions from the data at the equivalent of
435,000 and 800,000 miles) to determine the emissions performance at
the equivalent of 650,000 miles. We think it's appropriate to use
the data at the equivalent of 800,000 miles (rather than the
interpolated data at the equivalent of 650,000 miles) to account for
uncertainties in real world performance, particularly given the
significant increases in useful life, decreases in the numeric
levels of the standards, and the advanced nature of the
technologies.
Table III-19--EPA Stage 3 NOX Emissions Off-Cycle Operation Without Adjustments for Crankcase Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
CARB southern Grocery deliv.
Equivalent miles, ambient T ([deg]C) Bin No. route cycle cycle ACES EU ISC Drayage
--------------------------------------------------------------------------------------------------------------------------------------------------------
435,000, 25 [deg]C........................ 1 (g/hr).................... 0.7 1.0 0.9 0.4 0.3
2 (mg/hp-hr)................ 32 21 20 31 19
800,000, 25 [deg]C........................ 1 (g/hr).................... 0.7 3.3 1.5 0.4 1.1
2 (mg/hp-hr)................ 47 32 34 32 28
---------------------------------------------------------------
800,000, 2 to 9 [deg]C.................... 1 (g/hr).................... 1.4 Not tested
---------------------------------------------------------------
2 (mg/hp-hr)................ 87 Not tested
--------------------------------------------------------------------------------------------------------------------------------------------------------
a. Bin 1 Evaluation
Bin 1 includes the idle operation and some of the lower speed
operation that occurs during the FTP and LLC. However, it also includes
other types of low-load operation observed with in-use vehicles, such
as operation involving longer idle times than occur in the LLC. To
ensure that the bin 1 standard is feasible, we set the idle bin
standard at the level projected to be achievable engine-out with
exhaust temperatures below the aftertreatment light-off temperature. As
can be seen from the results in Table III-19, the EPA Stage 3 engine
performed well below the bin 1 NOX standards. The summary of
the results is located in Chapter 3 of the RIA.
For bin 1 we are finalizing NOX standard at a level
above what we have demonstrated because there are conditions in the
real world that may prevent the emissions control technology from being
as effective as demonstrated with the EPA Stage 3 engine. For example,
under extended idle operation the EGR rate may need to be reduced to
maintain engine durability. Under extended idle operation with cold
ambient temperatures, the aftertreatment system can lose NOX
reduction efficiency which can also increase NOX emissions.
Taking this under consideration, as well as other factors, we believe
that the final bin 1 NOX standard in Table III-17 is the
lowest achievable standard in MY 2027.
b. Bin 2 Evaluations
As can be seen see from the results in Table III-19, the
NOX emissions from the Stage 3 engine in bin 2 were below
the final off-cycle standards for each of the off-cycle duty-cycles.
The HC and CO emissions measured for each of these off-cycle duty
cycles were well below the final off-cycle standards for bin 2. PM
emissions were not measured during the off-cycle tests, but based on
the effectiveness of DPFs over all engine operation as seen with the
SET, FTP, and LLC, our assessment is that the final PM standards in Bin
2 are feasible. The summary of the results is located in Chapter 3 of
the RIA.
For bin 2, all the 25 [deg]C off-cycle duty cycles at a full useful
life of 800,000 miles had emission results below the NOX
certification standard of 58 mg/hp-hr shown in Table III-19.
Additionally, the CARB Southern Route Cycle run at ambient temperatures
under 10 [deg]C had emission results below the Heavy HDE NOX
in-use off-cycle standard of 106 mg/hp-hr which is the standard at 10
[deg]C as determined from Equation 40 CFR 1036.104-2. While this cycle
was run at temperatures above the minimum ambient temperature exclusion
limit of 5 [deg]C that we are finalizing, we expect actual HDIUT
testing to be less severe than the demonstration. Nonetheless, since
the results of the low ambient temperature testing demonstrated higher
NOX emissions at low temperatures, as shown in Table III-19,
we have finalized standards that are numerically higher at lower
temperatures to account for real-world temperature effects on the
aftertreatment system.
In the NPRM, we requested comment on the numerical values of the
off-cycle standards, as well as the overall structure of the off-cycle
program. We received comments recommending both lower and higher
numerical standards than were proposed. After considering comments, we
believe the off-cycle standards that we are finalizing are appropriate
and feasible values. See Response to Comments Section 11.3.1 for
further details on these comments and EPA's response to these comments.
4. Compliance and Flexibilities for Off-Cycle Standards
Given the similarities of the off-cycle standards and test
procedures to the current NTE requirements that we are
[[Page 4351]]
replacing starting in MY 2027, we evaluated the appropriateness of
applying the current NTE compliance provisions to the off-cycle
standards we are finalizing and determined which final compliance
requirements and flexibilities are applicable to the new final off-
cycle standards, as discussed immediately below.
i. Relation of Off-Cycle Standards To Defeat Devices
CAA section 203 prohibits bypassing or rendering inoperative a
certified engine's emission controls. When the engine is designed or
modified to do this, the engine is said to have a defeat device. With
today's engines, the greatest risks with respect to defeat devices
involve manipulation of the engine's electronic controls. EPA refers to
an element of design that manipulates emission controls as an Auxiliary
Emission Control Device (AECD).\293\ Unless explicitly permitted by
EPA, AECDs that reduce the effectiveness of emission control systems
under conditions which may reasonably be expected to be encountered in
normal vehicle operation and use are prohibited as defeat devices under
current 40 CFR 86.004-2.
---------------------------------------------------------------------------
\293\ 40 CFR 86.082-2 defines Auxiliary Emission Control Device
(AECD) to mean ``any element of design which senses temperature,
vehicle speed, engine RPM, transmission gear, manifold vacuum, or
any other parameter for the purpose of activating, modulating,
delaying, or deactivating the operation of any part of the emission
control system.''
---------------------------------------------------------------------------
For certification, EPA requires manufacturers to identify and
describe all AECDs.\294\ For any AECD that reduces the effectiveness of
the emission control system under conditions which may reasonably be
expected to be encountered in normal vehicle operation and use,
manufacturers must provide a detailed justification.\295\ We are
migrating the definition of defeat device from 40 CFR 86.004-2 to 40
CFR 1036.115(h) and clarifying that an AECD is not a defeat device if
such conditions are substantially included in the applicable procedure
for duty-cycle testing as described in 40 CFR 1036, subpart F. Such
AECDs are not treated as defeat devices because the manufacturer shows
that their engines are able to meet standards during duty-cycle testing
while the AECD is active. The AECD might reduce the effectiveness of
emission controls, but not so much that the engine fails to meet the
standards that apply.
---------------------------------------------------------------------------
\294\ See 40 CFR 86.094-21(b)(1)(i)(A).
\295\ See definition of ``defeat device'' in 40 CFR 86.004-2.
---------------------------------------------------------------------------
We do not extend this same treatment to off-cycle testing, for two
related reasons. First, we can have no assurance that the AECD is
adequately exercised during any off-cycle operation to support the
conclusion that the engine will consistently meet emission standards
over all off-cycle operation. Second, off-cycle testing may involve
operation over an infinite combination of engine speeds and loads, so
excluding AECDs from consideration as defeat devices during off-cycle
testing would make it practically impossible to conclude that an engine
has a defeat device.
If an engine meets duty-cycle standards and the engine has no
defeat devices, we should be able to expect engines to achieve a
comparable level of emission control for engine operation that is
different than what is represented by the certification duty cycles.
The off-cycle standards and measurement procedures allow for a modest
increase in emissions for operation that is different than the duty
cycle, but manufacturers may not change emission controls to increase
emissions to the off-cycle standard if those controls were needed to
meet the duty-cycle standards. The finalized off-cycle standards are
set at a level that is feasible under all operating conditions, so we
expect that under much of the engine operation the emissions are well
below the final off-cycle standards.
ii. Heavy-Duty In-Use Testing Program
Under the current manufacturer-run heavy-duty in-use testing
(HDIUT) program, EPA annually selects engine families to evaluate
whether engines are meeting current emissions standards. Once we submit
a test order to the manufacturer to initiate testing, it must contact
customers to recruit vehicles that use an engine from the selected
engine family. The manufacturer generally selects five unique vehicles
that have a good maintenance history, no malfunction indicators on, and
are within the engine's regulatory useful life for the requested engine
family. The tests require use of portable emissions measurement systems
(PEMS) that meet the requirements of 40 CFR part 1065, subpart J.
Manufacturers collect data from the selected vehicles over the course
of a day while they are used for their normal work and operated by a
regular driver, and then submit the data to EPA. Compliance is
currently evaluated with respect to the NTE standards.
With some modifications from proposal, we are continuing the HDIUT
program, with compliance with respect to the new off-cycle standards
and test procedures added to the program beginning with MY 2027
engines. As proposed, we are not carrying forward the Phase 2 HDIUT
requirements in 40 CFR 86.1915 once the NTE phases out after MY 2026.
Under the current NTE based off-cycle test program, if a manufacturer
is required to test ten engines under Phase 1 testing and less than
eight fully comply with the vehicle pass criteria in 40 CFR 86.1912, we
could require the manufacturer to initiate Phase 2 HDIUT testing which
would require manufacturers to test an additional 10 engines. After
consideration of comments, we are generally finalizing our overall long
term HDIUT program's engine testing steps and pass/fail criteria as
proposed; however, EPA believes that an interim approach in the initial
two years of the program is appropriate, as manufacturers transition to
the final standards, test procedures, and requirements, while still
providing overall compliance assurance during that transition. More
specifically, we are finalizing that compliance with the off-cycle
standards would be determined by testing a maximum of fifteen engines
for MYs 2027 and MY 2028 under the interim provisions, and ten engines
for MYs 2029 and later. As noted in the proposal, the testing of a
maximum of ten engines was the original limit under Phase 1 HDIUT
testing in 40 CFR 86.1915. Similar to the current Phase 1 HDIUT
requirements in 40 CFR 86.1912, the finalized 40 CFR 1036.425 and
finalized interim provision in 40 CFR 1036.150(z) require initially
testing five engines. Various outcomes are possible based on the
observed number of vehicle passes or failures from manufacturer-run in-
use testing, as well as other supplemental information. Under the
interim provisions for MYs 2027 and 2028, if four of the first test
vehicles meet the off-cycle standards, testing stops, and no other
action is required of the manufacturer for that diesel engine family.
For MYs 2029 and later, if five of the first test vehicles meet the
off-cycle standards, testing stops, and no other action is required of
the manufacturer for that diesel engine family. For MYs 2027 and 2028,
if two of those engines do not comply fully with the off-cycle bin
standards, the manufacturer would then test five additional engines for
a total of ten. For MYs 2029 and later, if one of those engines does
not comply fully with the off-cycle bin standards, the manufacturer
would then test a sixth engine. For MYs 2027 and 2028, if eight of the
ten engines tested pass, testing stops, and no other action is required
of the manufacturer for that diesel engine family under the program for
that model
[[Page 4352]]
year. For MYs 2029 and later, if five of the six engines tested pass,
testing stops, and no other action is required of the manufacturer for
that diesel engine family under the program for that model year. For
MYs 2027 and 2028, if three or more of the first ten engines tested do
not pass, the manufacturer may test up to five additional engines until
a maximum of fifteen engines have been tested. For MYs 2029 and later,
when two or more of the first six engines tested do not pass, the
manufacturer must test four additional engines until a total of ten
engines have been tested. If the arithmetic mean of the emissions from
the ten, or up to fifteen under the interim provisions, engine tests
determined in Sec. 1036.530(g), or Sec. 1036.150(z) under the interim
provisions, is at or below the off-cycle standard for each pollutant,
the engine family passes and no other action is required of the
manufacturer for that diesel engine family. If the arithmetic mean of
the emissions from the ten, or up to fifteen under the interim
provisions, engines for either of the two bins for any of the
pollutants is above the respective off-cycle bin standard, the engine
family fails and the manufacturer must join EPA in follow-up
discussions to determine whether any further testing, investigations,
data submissions, or other actions may be warranted. Under the final
requirements, the manufacturer may accept a fail result for the engine
family and discontinue testing at any point in the sequence of testing
the specified number of engines.
We received comment on the elimination of Phase 2 testing. See
Response to Comment Section 11.5.1 for further information on these
comments and EPA's response to these comments. As noted in the
preceding paragraphs, we are finalizing elimination of Phase 2 testing.
However, we also are clarifying what happens when an engine family
fails under the final program. In such a case, three outcomes are
possible. First, we may ultimately decide not to take further action if
no nonconformity is indicated after a thorough evaluation of the causes
or conditions that caused vehicles in the engine family to fail the
off-cycle standards, and a review of any other supplemental information
obtained separately by EPA or submitted by the manufacturer shows that
no significant nonconformity exists. Testing would then stop, and no
other action would be required of the manufacturer for that diesel
engine family under the program for that year. Second, we may seek some
form of remedial action from the manufacturer based on our evaluation
of the test results and review of other supplemental information.
Third, and finally, in situations where a significant nonconformity is
observed during testing, we may order a recall action for the diesel
engine family in question if the manufacturer does not voluntarily
initiate an acceptable remedial action.
In the NPRM, we proposed allowing manufacturers to test a minimum
of 2 engines using PEMS, in response to a test order program, provided
they measure, and report in-use data collected from the engine's on-
board NOX measurement system. EPA received comments
expressing concerns on the feasibility of this alternate in-use testing
option. Given meaningful uncertainties in whether technological
advancement of measurement capabilities of these sensors will occur by
MY 2027, at this time, EPA is not including the proposed option in 40
CFR 1036.405(g) and not finalizing this alternative test program option
in this action. The final in-use option for manufacturers to show
compliance with the off-cycle standard will require the use of
currently available PEMS to measure criteria pollutant emissions, with
the sampling and measurement of emission concentrations in a manner
similar to the current NTE in-use test program as described in 40 CFR
part 1036, subpart E, and Section III.C of this preamble. See Response
to Comment Section 11.5.3 for further information on these comments and
EPA's response to these comments.
In the NPRM, we proposed to not carry forward the provision in 40
CFR 86.1908(a)(6) that considers an engine misfueled if operated on a
biodiesel fuel blend that is either not listed as allowed or otherwise
indicated to be an unacceptable fuel in the vehicle's owner or operator
manual. We also proposed in 40 CFR 1036.415(c)(1) to allow vehicles to
be tested for compliance with the new off-cycle standards on any
commercially available biodiesel fuel blend that meets the
specifications for ASTM D975 or ASTM D7467.
We received comments on these proposed requirements. After
considering the comments, we have altered provisions in the final rule
from what was proposed. EPA agrees with the commenters' recommendation
to restrict in-use off-cycle standards testing on vehicles that have
been fueled with biodiesel to those that are either expressly allowed
in the vehicle's owner or operator manual or not otherwise indicated as
an unacceptable fuel in the vehicle's owner or operator manual or in
the engine manufacturer's published fuel recommendations. EPA believes,
as explained in section IV.H of this preamble, that data show biodiesel
is compliant with ASTM D975, D7467 and D6751, that the occurrence of
metal contamination in the fuel pool is extremely low, and that the
metal content of biodiesel is low. However, EPA understands that
manufacturers have little control over the quality of fuel that their
engines will encounter over years of in-use operation.\296\ To address
uncertainties, EPA is modifying the proposed approach to in-use off-
cycle standards testing and will allow manufacturers to continue to
exempt engines from in-use off-cycle standards testing if the engine is
being operated on biofuel that exceeds the manufacturers maximum
allowable biodiesel percentage usable in their engines, as specified in
the engine owner's manual. See 40 CFR 1036.415(c)(1).
---------------------------------------------------------------------------
\296\ At this time, as explained in the proposed rule, EPA did
not propose and is not taking final action to regulate biodiesel
blend metal content because the available data does not indicate
that there is widespread off-specification biodiesel blend stock or
biodiesel blends in the marketplace. EPA also notes that the request
to set a maximum nationwide biodiesel percentage of 20 percent is
outside the scope of this final rule.
---------------------------------------------------------------------------
EPA requested comment on a process for a manufacturer to receive
EPA approval to exempt test results from in-use off-cycle standards
testing from being considered for potential recall if an engine
manufacturer can show that the vehicle was historically fueled with
biodiesel blends whose B100 blendstock did not meet the ASTM D6751-20a
limit for Na, K, Ca, and/or Mg metal (metals which are a byproduct of
biodiesel production) or contaminated petroleum based fuels (i.e. if
the manufacturer can show that the vehicle was misfueled), and the
manufacturer can show that misfueling lead to degradation of the
emission control system performance. 40 CFR 1068.505 describes how
recall requirements apply for engines that have been properly
maintained and used. Given the risk of metal contamination from
biofuels and in some rare cases petroleum derived fuels, EPA will be
willing to engage with any information manufacturers can share to
demonstrate that the fueling history caused an engine to be
noncompliant based on improper maintenance or use. It is envisioned
that this engagement would include submission by the manufacturer of a
comparison of the degraded emission control system to a representative
compliant system of similar miles with respect to content of the
contaminant, including an analysis of the level of the poisoning agents
on the catalysts in the engine's aftertreatment system. This
[[Page 4353]]
process addresses concerns expressed by a commentor who stated that it
would be difficult if not impossible for a manufacturer to provide
``proof of source'' of the fuel contamination that led to the
degradation in catalyst performance. This clarifies that the
manufacturer must only determine the amount of poisoning agent present
versus a baseline aftertreatment system.
In the NPRM, we requested comment on the need to measure PM
emissions during in-use off-cycle testing of engines that comply with
MY 2027 or later standards if they are equipped with a DPF. PEMS
measurement is more complicated and time-consuming for PM measurements
than for gaseous pollutants such as NOX and eliminating it
for some or all of in-use off-cycle standards testing would provide
significant cost savings. We received comments both in support of and
in opposition to continuing to require measurement of PM during in-use
off-cycle standards testing. After considering these comments, EPA
believes that historic test results from the manufacturer run in-use
test program indicate that there is not a PM compliance problem for
properly maintained engines. Additionally, we believe that removing the
requirement for in-use off-cycle PM standards testing will not lead
manufacturers to stop using wall flow DPF technology to meet the PM
standards. Therefore, EPA is not including the proposed requirement for
manufacturers to measure PM in the final 40 CFR 1036.415(d)(1) but is
modifying that requirement from proposal to include a final provision
in this paragraph that EPA may request PM measurement and that
manufacturers must provide that measurement if EPA requests it.
Generally, EPA expects that test orders issued by EPA under 40 CFR
1036.405 will not include a requirement to measure PM.
Furthermore, EPA received comments on the subject of the need to
measure NMHC emissions during in-use off-cycle testing of engines that
comply with MY 2027 or later standards. After considering comments, EPA
believes that historic test results from the manufacturer run in-use
test program indicate that there is not an NMHC compliance problem for
properly maintained engines. EPA is not including the proposed
requirement for manufacturers to measure NMHC in the final 40 CFR
1036.415(d)(1) but is modifying that requirement from proposal to
include a provision in this paragraph that EPA may request NMHC
measurement and that manufacturers must provide that measurement if EPA
requests it. Generally, EPA expects that test orders issued by EPA
under 40 CFR 1036.405 will not include a requirement to measure NMHC.
See Response to Comment Section 11.5.5 for further information on these
comments and EPA's response to comments on the subject of in-use off-
cycle standards PM and NMHC testing.
iii. PEMS Accuracy Margin
EPA worked with engine manufacturers on a joint test program to
establish measurement allowance values to account for the measurement
uncertainty associated with in-use testing in the 2007-time frame for
gaseous emissions and the 2010-time frame for PM emissions to support
NTE in-use testing.\297\ \298\ \299\ PEMS measurement allowance values
in 40 CFR 86.1912 are 0.01 g/hp-hr for HC, 0.25 g/hp-hr for CO, 0.15 g/
hp-hr for NOX, and 0.006 g/hp-hr for PM. We are maintaining
the same values for HC, CO, and PM in this rulemaking. For
NOX we are finalizing an off-cycle NOX accuracy
margin (formerly known as measurement allowance) that is 5 percent of
the off-cycle standard for a given bin. This final accuracy margin is
supported by PEMS accuracy margin work at SwRI. The SwRI PEMS accuracy
margin testing was done on the Stage 3 engine, which was tested over
five field cycles with three different commercially available PEMS.
EPA's conclusion after assessing the results of that study, was that
accuracy margins set at 0.4 g/hr for bin 1 and 5 mg/hp-hr for bin 2
were appropriate.
---------------------------------------------------------------------------
\297\ Feist, M.D.; Sharp, C.A; Mason, R.L.; and Buckingham, J.P.
Determination of PEMS Measurement Allowances for Gaseous Emissions
Regulated Under the Heavy-Duty Diesel Engine In-Use Testing Program.
SwRI 12024, April 2007.
\298\ Feist, M.D.; Mason, R.L.; and Buckingham, J.P. Additional
Analyses of the Monte Carlo Model Developed for the Determination of
PEMS Measurement Allowances for Gaseous Emissions Regulated Under
the Heavy-Duty Diesel Engine In-Use Testing Program. SwRI[supreg]
12859. July 2007.
\299\ Khalek, I.A.; Bougher, T.L.; Mason, R.L.; and Buckingham,
J.P. PM-PEMS Measurement Allowance Determination. SwRI Project
03.14936.12. June 2010.
---------------------------------------------------------------------------
The accuracy margins we are finalizing differ from the 10 percent
of the standard margin proposed in the NPRM, which was based on an
earlier study by JRC. This SwRI PEMS accuracy margin study was on-going
at the time the NPRM was published, and the results were only available
post-NPRM publication.\300\ However, the NPRM did note that we would
consider the results of the SwRI PEMS study when they became available,
and that the final off-cycle bin NOX standards could be
higher or lower than what we proposed. EPA requested and received
comments on the value of the PEMS accuracy margin for NOX;
some commenters encouraged EPA to account for the SwRI PEMS accuracy
work that was carried out on the Stage 3 engine. We initially planned
to consider the results of this work and this was further supported
through recommendations by some commentors; thus, we believe that
incorporating the results of the latest study to determine an off-cycle
NOX accuracy margin is appropriate. The SwRI PEMS study is
further discussed in RIA Chapter 2. The study consisted of testing the
Stage 3 engine with three commercially available PEMS units over 19
different tests. These tests were 6 to 9 hours long, covering a wide
range of field operation. In addition, the Stage 3 engine was tested in
three different configurations to cover the range of emissions levels
expected from an engine both meeting and failing the final standards.
We believe, based on this robust data set that was evaluating using the
finalized test procedures, the SwRI study provides a more accurate
assessment of PEMS measurement uncertainty from field testing of heavy-
duty engines than what was determined from the JRC study that we relied
on in the proposal for the proposed 10 percent margin. See Response to
Comment Section 11.6 for further information on these comments and
EPA's response to these comments.
---------------------------------------------------------------------------
\300\ The data and the results from the study were added to the
public docket prior to the signing of the final rule.
---------------------------------------------------------------------------
It should be noted that our off-cycle test procedures already
include a linear zero and span drift correction over at least the shift
day, and we are finalizing requirements for at least hourly zero drift
checks over the course of the shift day on purified air. We believe
that the addition of these checks and the additional improvements we
implemented helped facilitate a measurement error that is lower than
the analytically derived JRC value of 10 percent.\301\
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\301\ Giechaskiel B., Valverde V., Clairotte M. 2020 Assessment
of Portable Emissions Measurement Systems (PEMS) Measurement
Uncertainty. JRC124017, EUR 30591 EN. https://publications.europa.eu/en/publications.
---------------------------------------------------------------------------
We are updating 40 CFR 1065.935 to require hourly zeroing of the
PEMS analyzers using purified air for all analyzers. We are also
updating the drift limits for NOX analyzers to improve data
quality. Specifically, for NOX analyzers, we are requiring
an hourly or more frequent zero verification limit of 2.5 ppm, a zero-
drift limit over the entire shift day of 10 ppm, and a span drift limit
between the beginning and end of the shift day or more frequent span
verification(s) of 4 percent of the
[[Page 4354]]
measured span value. In the NPRM, we requested comment on the test
procedure updates in 40 CFR 1065.935 and any changes that would reduce
the PEMS measurement uncertainty. We received no comments on this topic
other than a few minor edits and are finalizing these updates with
minor edits for clarification.
iv. Demonstrating Off-Cycle Standards for Certification
Consistent with current certification requirements in 40 CFR
86.007-21(p)(1), we are finalizing a new paragraph in 40 CFR
1036.205(p) that requires manufacturers to provide a statement in their
application for certification that their engine complies with the off-
cycle standards, along with testing or other information to support
that conclusion. We are finalizing this provision as proposed.
D. Summary of Spark-Ignition HDE Exhaust Emission Standards and Test
Procedures
This section summarizes the exhaust emission standards, test
procedures, and other requirements and flexibilities we are finalizing
for certain spark-ignition (SI) heavy-duty engines. The exhaust
emission provisions in this section apply for SI engines installed in
vehicles above 14,000 lb GVWR and incomplete vehicles at or below
14,000 lb GVWR, but do not include engines voluntarily certified to or
installed in vehicles subject to 40 CFR part 86, subpart S.
As described in this Section III.D, Spark-ignition HDE
certification will continue to be based on emission performance in lab-
based engine dynamometer testing, which will include a new SET duty
cycle to address high load operation. High load temperature protection
and idle emission control requirements are also added to supplement our
current FTP and new SET duty cycles. We are also lengthening the useful
life and emissions-related warranty periods for all heavy-duty engines,
including Spark-ignition HDE, as detailed in Sections IV.A and IV.B.1
of this preamble.
The final exhaust emission standards in 40 CFR 1037.104 apply
starting in MY 2027. This final rule includes new standards over the
FTP duty cycle currently used for certification, as well as new
standards over the SET duty cycle to ensure manufacturers of Spark-
ignition HDE are designing their engines to address emissions in during
operation that is not covered by the FTP. The new standards are shown
in Table III-20.
Table III-20--Final Duty Cycle Emission Standards for Spark-Ignition HDE
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Model year 2026 and earlier \a\ Model year 2027 and later
-------------------------------------------------------------------------------------------------------------------------------
Duty cycle NOX (mg/hp- NOX (mg/hp-
hr) HC (mg/hp-hr) PM (mg/hp-hr) CO (g/hp-hr) hr) HC (mg/hp-hr) PM (mg/hp-hr) CO (g/hp-hr)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
SET............................................................. .............. .............. .............. .............. 35 60 5 14.4
FTP............................................................. 200 140 10 14.4 35 60 5 6.0
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Current emission standards for NOX, HC, and PM were converted from g/hp-hr to mg/hp-hr to compare with the final standards.
Our proposal included two options of fuel-neutral standards that
applied the same numerical standards across all primary intended
service classes. The proposed NOX and PM standards for the
SET and FTP duty cycles were based on the emission performance of
technologies evaluated in our HD CI engine technology demonstration
program.\302\ We based the proposed SET and FTP standards for HC and CO
on HD SI engine performance.
---------------------------------------------------------------------------
\302\ Our assessment of the projected technology package for
compression-ignition engines is based on both CARB's and EPA's
technology demonstration programs. See Section III.B for a
description of those technologies and test programs.
---------------------------------------------------------------------------
Three organizations specifically expressed support for adopting the
standards of proposed Option 1 for Spark-ignition HDE. The final
standards are based largely on the emission levels of proposed Option
1, with some revisions to account for a single-step program, starting
in MY 2027. Some organizations commented that the proposed SI standards
were challenging enough to need the flexibility of ABT for HC and CO.
Consistent with the proposal for this rule, we are finalizing an ABT
program for NOX credits only and are discontinuing the
current options for manufacturers to generate HC and PM credits. We did
not request comment on and are not finalizing an option for
manufacturers to generate credits for CO. See Section IV.G of this
preamble and section 12 of the Response to Comments document for more
information on the final ABT program.
We are remaining generally consistent with a fuel neutral approach
in the final SET and FTP standards, with the exception of CO for Spark-
ignition HDE over the new SET duty cycle. We expand on our rationale
for this deviation from fuel neutrality in Section III.D.1 where we
also describe our rationale for the final program, including a summary
of the feasibility demonstration, available data, and comments
received.
After considering comments, we are revising three other proposed
provisions for Spark-ignition HDE as described in Section . Two new
requirements in 40 CFR 1036.115(j) focus on ensuring catalyst
efficiency at low loads and proper thermal management at high loads. We
are finalizing, with additional clarification, a new OBD flexibility
for ``sister vehicles''. We did not propose and are not finalizing
separate off-cycle standards, manufacturer-run in-use testing
requirements, or a low-load duty cycle for Spark-ignition HDE at this
time.\303\
---------------------------------------------------------------------------
\303\ See section 3 of the Response to Comments document for
more information.
---------------------------------------------------------------------------
The proposed rule provided an extensive discussion of the rationale
and information supporting the proposed standards (87 FR 17479, March
28, 2022). The RIA includes additional information related to the range
of technologies to control criteria emissions, background on applicable
test procedures, and the full feasibility analysis for Spark-ignition
HDE. See also section 3 of the Response to Comments for a detailed
discussion of the comments and how they have informed this final rule.
1. Basis of the Final Exhaust Emission Standards and Test Procedures
EPA conducted a program with SwRI to better understand the
emissions performance limitations of current heavy-duty SI engines as
well as investigate the feasibility of advanced three-way catalyst
aftertreatment and technologies and strategies to meet our proposed
exhaust emission standards.\304\ Our demonstration included the use of
advanced catalyst
[[Page 4355]]
technologies artificially aged to the equivalent of 250,000 miles and
engine downspeeding. Our feasibility analyses for the exhaust emission
standards are based on the SwRI demonstration program. Feasibility of
the FTP standards is further supported by compliance data submitted by
manufacturers for the 2019 model year. We also support the feasibility
of the SET standards using engine fuel mapping data from a test program
performed by the agency as part of the HD GHG Phase 2 rulemaking. See
Chapter 3.2 of the RIA for more details related to the SwRI
demonstration program and the two supporting datasets.
---------------------------------------------------------------------------
\304\ Ross, M. (2022). Heavy-Duty Gasoline Engine Low
NOX Demonstration. Southwest Research Institute. Final
Report EPA Contract 68HERC20D0014.
---------------------------------------------------------------------------
Results from our SI HDE technology demonstration program (see Table
III-21 and Table III-22) show that the NOX standards based
on our CI engine feasibility analysis are also feasible for SI HDEs
over the SET and FTP duty cycles. The NOX standard was
achieved in this test program by implementing an advanced catalyst with
minor catalyst system design changes, and NOX levels were
further improved with engine down-speeding. The emission control
strategies that we evaluated did not specifically target PM emissions,
but we note that PM emissions remained low in our demonstration. We
project SI HDE manufacturers will maintain near-zero PM levels with
limited effort. The following sections discuss the feasibility of the
HC and CO standards over each of the duty cycles and the basis for our
final numeric standards' levels.
i. Federal Test Procedure and Standards for Spark-Ignition HDE
After considering comments, we are finalizing FTP standards that
differ from our proposed options for Spark-ignition HDE. We are
finalizing standards of 35 mg/hp-hr NOX, 5 mg/hp-hr PM, 60
mg/hp-hr HC, and 6.0 g/hp-hr CO over the FTP duty cycle in a single
step for MY 2027 and later engines. The NOX and HC standards
match the MY 2027 step of proposed Option 1; the PM and CO standards
match the MY 2031 step of Option 1. All of these standards were
demonstrated to be technologically feasible in EPA's SI engine test
program.
As shown in Table III-21, use of advanced catalysts provided
NOX emission levels over the FTP duty cycle well below
today's standards and below the certification levels of some of the
best performing engines certified in recent years.\305\ Engine down-
speeding further decreased CO emissions while maintaining
NOX, NMHC, and PM control. Engine down-speeding also
resulted in a small improvement in fuel consumption over the FTP duty
cycle, with fuel consumption being reduced from 0.46 to 0.45 lb/hp-hr.
See Chapter 3.2.3 of the RIA for an expanded description of the test
program and results.
---------------------------------------------------------------------------
\305\ As presented in Chapter 3.2 of the RIA, MY 2019 gasoline-
fueled HD SI engine certification results included NOX
levels ranging from 40 to 240 mg/hp-hr at a useful life of 110,000
miles. MY 2019-2021 alternative-fueled (CNG, LPG) HD SI engine
certification results included NOx levels ranging from 6 to 70 mg/
hp-hr at the same useful life.
Table III-21--Exhaust Emission Results From FTP Duty Cycle Testing in the HD SI Technology Demonstration
----------------------------------------------------------------------------------------------------------------
NOX (mg/hp-
hr) PM (mg/hp-hr) HC (mg/hp-hr) CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
Current Standards MY 2026 and earlier........... 200 10 140 14.4
Final Standards MY 2027 and later............... 35 5 60 6
Test Program Base Engine with Advanced Catalyst 19 4.8 32 4.9
\a\............................................
Test Program Down-sped Engine with Advanced 18 4.5 35 0.25
Catalyst \b\...................................
----------------------------------------------------------------------------------------------------------------
\a\ Base engine's manufacturer-stated maximum test speed is 4715 RPM; advanced catalyst aged to 250,000 miles.
\b\ Down-sped engine's maximum test speed lowered to 4000 RPM; advanced catalyst aged to 250,000 miles.
All SI HDEs currently on the market use a three-way catalyst (TWC)
to simultaneously control NOX, HC, and CO emissions.\306\ We
project most manufacturers will continue to use TWC technology and will
also adopt advanced catalyst washcoat technologies and refine their
existing catalyst thermal protection (fuel enrichment) strategies to
prevent damage to engine and catalyst components over the longer useful
life period we have finalized. We expect manufacturers, who design and
have full access to the engine controls, could achieve similar emission
performance as we demonstrated by adopting other, more targeted
approaches, including a combination of calibration changes, optimized
catalyst location, and fuel control strategies that EPA was unable to
evaluate in our demonstration program due to limited access to
proprietary engine controls.
---------------------------------------------------------------------------
\306\ See Chapter 1.2 of the RIA for a detailed description of
the TWC technology and other strategies HD SI manufacturers use to
control criteria emissions.
---------------------------------------------------------------------------
In the proposal we described how the FTP duty cycle did not
sufficiently incentivize SI HDE manufacturers to address fuel
enrichment and the associated CO emissions that are common under higher
load operations in the real-world. In response to our proposed rule,
one manufacturer shared technical information with us regarding an SI
engine architecture under development that is expected to reduce or
eliminate enrichment and the associated CO emissions.\307\ The company
indicated that the low CO emissions may come at the expense of HC
emission reduction in certain operation represented by the FTP duty
cycle, and reiterated their request for an 80 mg/hp-hr HC standard, as
was stated in their written comments. We are not finalizing an HC
standard of 80 mg/hp-hr as requested in comment. For the FTP duty
cycle, the EPA test program achieved HC levels more than half of the
requested level without compromising NOX or CO emission
control (see Table III-21), which clearly demonstrates feasibility.
---------------------------------------------------------------------------
\307\ U.S. EPA. Stakeholder Meeting Log. December 2022.
---------------------------------------------------------------------------
While we demonstrated emission levels below the final standards of
60 mg HC/hp-hr and 35 mg NOX/hp-hr over the FTP duty cycle
in our SI HDE testing program, we expect manufacturers to apply a
compliance margin to their certification test results to account for
uncertainties, such as production variation. Additionally, we believe
manufacturers would have required additional lead time to implement the
demonstrated emission levels broadly across all heavy-duty SI engine
platforms for the final useful life periods. Since we are finalizing a
single-step program starting in MY 2027, as discussed in Section
III.A.3 of this preamble, we continue to consider 60 mg HC/hp-hr and 35
mg NOX/hp-hr the appropriate level of the standards for
[[Page 4356]]
that model year, as proposed in the MY 2027 step of proposed Option 1.
ii. Supplemental Emission Test and Standards for Spark-Ignition HDE
The existing SET duty cycle, currently only applicable to CI
engines, is a ramped modal cycle covering 13 steady-state torque and
engine speed points that is intended to exercise the engine over
sustained higher load and higher speed operation. Historically, in
light of the limited range of applications and sales volumes of SI
heavy-duty engines, especially compared to CI engines, we believed the
FTP duty cycle was sufficient to represent the high-load and high-speed
operation of SI engine-powered heavy-duty vehicles. As the market for
SI engines increases for use in larger vehicle classes, these engines
are more likely to operate under extended high-load conditions. To
address these market shifts, we proposed to apply the SET duty cycle
and new SET standards to Spark-ignition HDE, starting in model year
2027. This new cycle would ensure that emission controls are properly
functioning in the high load and speed conditions covered by the SET.
We are finalizing the addition of the SET duty cycle for the Spark-
ignition HDE primary intended service class, as proposed.\308\ We
requested comment on revisions we should consider for the CI-based SET
procedure to adapt it for SI engines. We received no comments on
changes to the procedure itself and the SET standards for Spark-
ignition HDE are based on the same SET procedure as we are finalizing
for heavy-duty CI engines. After considering comments, we are
finalizing SET standards that differ from our proposed options for
Spark-ignition HDE.
---------------------------------------------------------------------------
\308\ See our updates to the SET test procedure in 40 CFR
1036.505.
---------------------------------------------------------------------------
The EPA HD SI technology demonstration program evaluated emission
performance over the SET duty cycle. As shown in Table III-22, the
NOX and NMHC emissions over the SET duty cycle were
substantially lower than the emissions from the FTP duty cycle (see
Table III-21). Lower levels of NMHC were demonstrated, but at the
expense of increased CO emissions in those higher load operating
conditions. Engine down-speeding improved CO emissions significantly,
while NOX, NMHC, and PM remained low.\309\ The considerably
lower NOX and HC in our SET duty cycle demonstration results
leave enough room for manufacturers to calibrate the tradeoff in TWC
emission control of NOX, HC, and CO to continue to fine-tune
CO. See Chapter 3.2 of the RIA for an expanded description of the test
program and results.
---------------------------------------------------------------------------
\309\ Engine down-speeding also resulted in a small improvement
in brake specific fuel consumption over the SET duty cycle reducing
from 0.46 to 0.44 lb/hp-hr.
Table III-22--Exhaust Emission Results From SET Duty Cycle Testing in the HD SI Technology Demonstration
----------------------------------------------------------------------------------------------------------------
NOX (mg/hp-
hr) PM (mg/hp-hr) HC (mg/hp-hr) CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
Final Standards MY 2027 and later............... 35 5 60 14.4
Test Program Base Engine with Advanced Catalyst 8 \c\ 7 6 36.7
\a\............................................
Test Program Down-sped Engine with Advanced 5 3 1 7.21
Catalyst \b\...................................
----------------------------------------------------------------------------------------------------------------
\a\ Base engine's manufacturer-stated maximum test speed is 4715 RPM; advanced catalyst aged to 250,000 miles.
\b\ Down-sped engine's maximum test speed lowered to 4000 RPM; advanced catalyst aged to 250,000 miles.
\c\ As noted in Chapter 3.2 of the RIA, the higher PM value was due to material separating from the catalyst mat
during the test and is not indicative of the engine's ability to control engine-generated PM emissions at the
higher load conditions of the SET.
Similar to our discussion related to the FTP standards, we expect
manufacturers, who design and have full access to the engine controls,
could achieve emission levels comparable to or lower than our
feasibility demonstration over the SET duty cycle by adopting other
approaches, including a combination of calibration changes, optimized
catalyst location, and fuel control strategies that EPA was unable to
evaluate due to limited access to proprietary engine controls. In fact,
we are aware of advanced engine architectures that can reduce or
eliminate enrichment, and the associated CO emissions, by maintaining
closed loop operation.\310\
---------------------------------------------------------------------------
\310\ See Chapter 1 of the RIA for a description of fuel
enrichment, when engine operation deviates from closed loop, and its
potential impact on emissions.
---------------------------------------------------------------------------
We proposed Spark-ignition HDE standards for HC and CO emissions on
the SET cycle that were numerically equivalent to the respective
proposed FTP standards. Our intent was to ensure that SI engine
manufacturers utilize emission control hardware and calibration
strategies to control emissions during high load operation to levels
similar to the FTP duty cycle.\311\ We retain this approach for HC,
but, after considering comments, the final CO standard is revised from
that proposed. One commenter indicated that manufacturers would need CO
credits to achieve the proposed standards. Another commenter suggested
that EPA underestimated the modifications manufacturers would need to
make to fully transition away from the fuel enrichment strategies they
currently use to protect their engines. The same commenter requested
that EPA delay the SET to start in model year 2031 or temporarily
exclude the highest load points over the test to provide additional
lead time for manufacturers.
---------------------------------------------------------------------------
\311\ Test results presented in Chapter 3.2 of the RIA indicate
that these standards are achievable when the engine controls limit
fuel enrichment and maintain closed loop control of the fuel-air
ratio.
---------------------------------------------------------------------------
We are not finalizing an option for manufacturers to generate CO
credits. We believe a delayed implementation of SET, as requested,
would further delay manufacturers' motivation to focus on high load
operation to reduce enrichment and the associated emissions reductions
that would result. Additionally, our objective for adding new standards
over the SET duty cycle is to capture the prolonged, high-load
operation not currently represented in the FTP duty cycle, and the
commenter's recommendation to exclude the points of highest load would
be counter to that objective.
We agree with commenters that the new SET duty cycle and standards
will be a challenge for heavy-duty SI manufacturers but maintain that
setting a feasible technology-forcing CO standard is consistent with
our authority under the CAA. After further considering the comments and
assessing CO data from the EPA heavy-duty SI test program, the final
new CO standard we
[[Page 4357]]
are adopting is less stringent than proposed to provide manufacturers
additional margin for ensuring compliance with that pollutant's
standard over the new test procedure for Spark-ignition HDE. Given this
final standard, we determined that neither ABT or more lead time are
appropriate or required. The Spark-ignition HDE standard for CO
emissions on the SET duty-cycle established in this final rule is
numerically equivalent to the current FTP standard of 14.4 g/hp-hr.
2. Other Provisions for Spark-Ignition HDE
This Section III.D.2 describes other provisions we proposed and are
finalizing with revisions from proposal in this rule. The following
three provisions address information manufacturers will share with EPA
as part of their certification and we are adding clarification where
needed after considering comments. See also section 3 of the Response
to Comments for a detailed discussion of the comments summarized in
this section and how they have informed the updates we are finalizing
for these three provisions.
Idle Control for Spark-Ignition HDE
We proposed to add a new paragraph at 40 CFR 1036.115(j)(1) to
require manufacturers to show how they maintain a catalyst bed
temperature of 350 [deg]C in their application for certification or get
approval for an alternative strategy that maintains low emissions
during idle. As described in Chapter 3.2 of the RIA, prolonged idling
events may allow the catalyst to cool and reduce its efficiency,
resulting in emission increases until the catalyst temperatures
increase. Our recent HD SI test program showed idle events that extend
beyond four minutes allow the catalyst to cool below the light-off
temperature of 350 [deg]C. The current heavy-duty SET and FTP duty
cycles do not include sufficiently long idle periods to represent these
real-world conditions where the exhaust system cools below the
catalyst's light-off temperature.
We continue to believe that a 350 [deg]C lower bound for catalysts
will sufficiently ensure emission control is maintained during idle
without additional manufacturer testing. We are finalizing the 350
[deg]C target and the option for manufacturers to request approval for
a different strategy, as proposed. We are revising the final
requirement from our proposal to also allow manufacturers to request
approval of a temperature lower than 350 [deg]C, after considering
comments that requested that we replace the 350 [deg]C temperature with
the more generic ``light-off temperature'' to account for catalysts
with other formulations or locations relative to the engine.
i. Thermal Protection Temperature Modeling Validation
The existing regulations require manufacturers to report any
catalyst protection strategy that reduces the effectiveness of emission
controls as an AECD in their application for certification.\312\ The
engine controls used to implement these strategies often rely on a
modeling algorithm to predict high exhaust temperatures and to disable
the catalyst, which can change the emission control strategy and
directly impact real world emissions. The accuracy of these models used
by manufacturers is critical in both ensuring the durability of the
emission control equipment and preventing excessive emissions that
could result from unnecessary or premature activation of thermal
protection strategies.
---------------------------------------------------------------------------
\312\ See 40 CFR 86.094-21(b)(1)(i) and our migration of those
provisions to final 40 CFR 1036.205(b).
---------------------------------------------------------------------------
To ensure that a manufacturer's model accurately estimates the
temperatures at which thermal protection modes are engaged, we proposed
a validation process during certification in a new paragraph 40 CFR
1036.115(j)(2) to demonstrate the model performance.
Several commenters opposed the proposed requirement that
manufacturers demonstrate a 5 [deg]C accuracy between modelled and
actual exhaust and emission component temperatures and expressed
concern with the ability to prove correlation at this level and lack of
details on the procedure for measuring the temperatures. Our final,
revised approach still ensures EPA has the information needed to
appropriately assess a manufacturer's AECD strategy, without a specific
accuracy requirement.
Our final 40 CFR 1036.115(j)(2) clarifies that the new validation
process is a requirement in addition to the requirements for any SI
engine applications for certification that include an AECD for thermal
protection.\313\ Instead of the proposed 5 [deg]C accuracy requirement,
a manufacturer will describe why they rely on any AECDs, instead of
other engine designs, for thermal protection of catalyst or other
emission-related components. They will also describe the accuracy of
any modeled or measured temperatures used to activate the AECD. Instead
of requiring manufacturers to submit second-by-second data upfront in
the application for certification to demonstrate a specific accuracy
requirement is met, the final requirement gives EPA discretion to
request the information at certification. We note that our final
revised requirements apply the same validation process for modeled and
measured temperatures that activate an AECD and that this requirement
would not apply if manufacturers certify their engines without an AECD
for enrichment as thermal protection.
---------------------------------------------------------------------------
\313\ These requirements are in place today under existing 40
CFR 86.094-21(b)(1)(i), which have been migrated to 40 CFR
1036.205(b) in this final rule.
---------------------------------------------------------------------------
ii. OBD Flexibilities
In recognition that there can be some significant overlap in the
technologies and emission control systems adopted for products in the
chassis-certified and engine-certified markets, we proposed an OBD
flexibility to limit the data requirements for engine-certified
products that use the same engines and generally share similar emission
controls (i.e., are ``sister vehicles'') with chassis-certified
products. Specifically, in a new 40 CFR 1036.110(a)(2), we proposed to
allow vehicle manufacturers the option to request approval to certify
the OBD of their SI, engine-certified products using data from similar
chassis-certified Class 2b and Class 3 vehicles that meet the
provisions of 40 CFR 86.1806-17.
Two organizations commented in support of the proposed OBD
flexibility and with one suggesting some revisions to the proposed
regulatory language. The commenter suggested that the expression `share
essential design characteristics' was too vague, and requested EPA
provide more specific information on what EPA will use to make their
determination. We disagree that more specific information is needed. We
are relying on the manufacturers to identify the design characteristics
and justify their request as part of the certification process. We are
adjusting the final regulatory text to clarify how the vehicles above
and below 14,000 lbs GVWR must use the same engine and share similar
emission controls, but are otherwise finalizing this OBD flexibility as
proposed.
E. Summary of Spark-Ignition HDV Refueling Emission Standards and Test
Procedures
All sizes of complete and incomplete heavy-duty vehicles have been
subject to evaporative emission standards for many years. Similarly,
all sizes of complete heavy-duty vehicles are subject to refueling
standards. We most
[[Page 4358]]
recently applied the refueling standards to complete heavy-duty
vehicles above 14,000 pounds GVWR starting with model year 2022 (81 FR
74048, Oct. 25, 2016).
We proposed to amend 40 CFR 1037.103 to apply the same refueling
standard of 0.20 grams hydrocarbon per gallon of dispensed fuel to
incomplete heavy-duty vehicles above 14,000 pounds GVWR starting with
model year 2027 over a useful life of 150,000 miles or 15 years
(whichever comes first). We further proposed to apply the same testing
and certification procedures that currently apply for complete heavy-
duty vehicles. We are adopting this standard and testing and
certification procedures as proposed, with some changes to the proposed
rule as noted in this section. As noted in 40 CFR 1037.103(a)(2), the
standards apply for vehicles that run on gasoline, other volatile
liquid fuels, and gaseous fuels.
The proposed rule provided an extensive discussion of the history
of evaporative and refueling standards for heavy-duty vehicles, along
with rationale and information supporting the proposed standards (87 FR
17489, March 28, 2022). The RIA includes additional information related
to control technology, feasibility, and test procedures. See also
section 3 of the Response to Comments for a detailed discussion of the
comments and the changes we made to the proposed rule.
Some commenters advocated for applying the refueling standards also
to incomplete heavy-duty vehicles at or below 14,000 pounds GVWR.
Specifically, some manufacturers commented that they would need a
phase-in schedule that allowed more lead time beyond the proposed MY
2027 start of the refueling standards for incomplete vehicles above
14,000 pounds GVWR, and that EPA should consider a longer phase-in that
also included refueling standards for incomplete vehicles at or below
14,000 pounds GVWR. In EPA's judgment, the design challenge for meeting
the new refueling standards will mainly involve larger evaporative
canisters, resizing purge valves, and recalibrating for higher flow of
vapors from the evaporative canister into the engine's intake. Four
years of lead time is adequate for designing, certifying, and
implementing these design solutions. We are therefore finalizing the
proposed start of refueling standards in MY 2027 for all incomplete
heavy-duty vehicles above 14,000 pounds GVWR.
At the same time, as manufacturers suggested, expanding the scope
of certification over a longer time frame may be advantageous for
implementing design changes across their product line in addition to
the environmental gain from applying refueling controls to a greater
number of vehicles. We did not propose refueling standards for vehicles
at or below 14,000 pounds GVWR and we therefore do not adopt such
standards in this final rule. However, the manufacturers' suggestion to
consider a package of changes to both expand the scope of the standards
and increase the lead time for meeting standards has led us to adopt an
optional alternative phase-in. Under the alternative phase-in
compliance pathway, instead of certifying all vehicles above 14,000
pounds GVWR to the refueling standard in MY 2027, manufacturers can opt
into the alternate phase-in that applies for all incomplete heavy-duty
vehicles, regardless of GVWR. The alternative phase-in starts at 40
percent of production in MYs 2026 and 2027, followed by 80 percent of
production in MYs 2028 and 2029, ramping up to 100 percent of
production in MY 2030. Phase-in calculations are based on projected
nationwide production volume of all incomplete heavy-duty vehicles
subject to refueling emission standards under 40 CFR 86.1813-17.
Specifying the phase-in schedule in two-year increments allows
manufacturers greater flexibility for integrating emission controls
across their product line.
Manufacturers may choose either schedule of standards; however,
they must satisfy at least one of the two. That is, if manufacturers do
not certify all their incomplete heavy-duty vehicles above 14,000
pounds GVWR to the refueling standards in MY 2027, the alternate phase-
in schedule described in 40 CFR 86.1813-17(b) becomes mandatory to
avoid noncompliance. Conversely, if manufacturers do not meet the
alternative phase-in requirement for MY 2026, they must certify all
their incomplete heavy-duty vehicles above 14,000 pounds GVWR to the
refueling standard in MY 2027 to avoid noncompliance. See the final 40
CFR 86.1813-17(b) for the detailed specifications for the alternative
phase-in schedule.
We received several comments suggesting that we adjust various
aspects of the testing and certification procedures for heavy-duty
vehicles meeting the evaporative and refueling standards. Consideration
of these comments led us to include some changes from proposal for the
final rule. First, we are revising 40 CFR 1037.103 to add a reference
to the provisions from 40 CFR part 86, subpart S, that are related to
the refueling standards. This is intended to make clear that the
overall certification protocol from 40 CFR part 86, subpart S, applies
for heavy-duty vehicles above 14,000 pounds GVWR (see also existing 40
CFR 1037.201(h)). This applies, for example, for durability procedures,
useful life, and information requirements for certifying vehicles.
Along those lines, we are adding provisions to 40 CFR 86.1821-01 to
clarify how manufacturers need to separately certify vehicles above
14,000 pounds GVWR by dividing them into different families even if
they have the same design characteristics as smaller vehicles. This is
consistent with the way we have been certifying vehicles to evaporative
and refueling standards.
Second, we are modifying the test procedures for vehicles with fuel
tank capacity above 50 gallons. These vehicles have very large
quantities of vapor generation and correspondingly large evaporative
and refueling canisters. The evaporative test procedures call for
manufacturers to design their vehicles to purge a canister over about
11 miles of driving (a single FTP duty cycle) before the diurnal test,
which requires the vehicle to control the vapors generated over two
simulated hot summer days of parking. We share manufacturers' concern
that the operating characteristics of these engines and vehicles do not
support achieving that level of emission control. We are therefore
revising the two-day diurnal test procedure at 40 CFR 86.137-94(b)(24)
and the Bleed Emission Test Procedure at 40 CFR 86.1813-17(a)(2)(iii)
to include a second FTP duty cycle with an additional 11 miles of
driving before starting the diurnal measurement procedure.
Third, manufacturers pointed out that the existing test procedures
don't adequately describe how to perform a refueling emission
measurement with vehicles that have two fuel tanks with separate filler
necks. We are amending the final rule to include a provision to direct
manufacturers to use good engineering judgment for testing vehicles in
a dual-tank configuration. It should be straightforward to do the
testing with successive refills for the two tanks and combining the
measured values into a single result. Rather than specifying detailed
adjustments to the procedure, allowing manufacturers the discretion to
perform that testing and computation consistent with good engineering
judgment will be enough to ensure a proper outcome.
Table III-23 summarizes the cost estimations for the different
technological approaches to controlling refueling emissions that EPA
evaluated. See Chapter 3.2.3.2 of the RIA for the
[[Page 4359]]
details. In calculating the overall cost, we used $25 (2019 dollars),
the average of both approaches, to represent the cost for manufacturers
to adopt the additional canister capacity and hardware to meet our new
refueling emission standards for incomplete vehicles above 14,000 lb
GVWR. See also Section V of this preamble for a summary of our overall
program cost and Chapter 7 of the RIA for more details on our overall
program cost.
Table III-23--Summary of Projected Per-Vehicle Costs To Meet the Refueling Emission Standards
----------------------------------------------------------------------------------------------------------------
Liquid seal Mechanical seal
---------------------------------------------------------------
Dual existing Dual existing
New canister canisters in New canister canisters in
series series
----------------------------------------------------------------------------------------------------------------
Additional Canister Costs....................... $20 $15 $8 $8
----------------------------------------------------------------------------------------------------------------
Additional Tooling \a\.......................... 0.50
0.50
----------------------------------------------------------------------------------------------------------------
Flow Control Valves............................. 6.50
6.50
----------------------------------------------------------------------------------------------------------------
Seal............................................ 0 0 10
----------------------------------------------------------------------------------------------------------------
Total....................................... 27 22 25
----------------------------------------------------------------------------------------------------------------
a Assumes the retooling costs are spread over a five-year period.
Incomplete vehicles above 14,000 lb GVWR with dual fuel tanks may
require some unique accommodations to adopt onboard refueling vapor
recovery (ORVR) systems. A chassis configuration with dual fuel tanks
would need separate canisters and separate filler pipes and seals for
each fuel tank. Depending on the design, a dual fuel tank chassis
configuration may require a separate purge valve for each fuel tank. We
assume manufacturers will install one additional purge valve for dual
fuel tank applications that also incorporate independent canisters for
the second fuel tank/canister configuration, and that manufacturers
adopting a mechanical seal in their filler pipe will install an anti-
spitback valve for each filler pipe. See Chapter 1.2.4.5 of the RIA for
a summary of the design considerations for these fuel tank
configurations. We did not include an estimate of the impact of dual
fuel tank vehicles in our cost analysis of the new refueling emission
standards, as the population of these vehicles is very low and we
expect minimal increase in the total average costs.
IV. Compliance Provisions and Flexibilities
EPA certification is a fundamental requirement of the Clean Air Act
for manufacturers of heavy-duty highway engines. EPA has employed
significant discretion over the past several decades in designing and
updating many aspects of our heavy-duty engine and vehicle
certification and compliance programs. In the following sections, we
discuss several revised provisions that we believe will increase the
effectiveness of our regulations.
As noted in Section I, we are migrating our criteria pollutant
regulations for model years 2027 and later heavy-duty highway engines
from their current location in 40 CFR part 86, subpart A, to 40 CFR
part 1036.\314\ Consistent with this migration, the compliance
provisions discussed in this section refer to the final regulations in
their new location in part 1036. In general, this migration is not
intended to change the compliance program specified in part 86, except
as specifically finalized in this rulemaking. See Section III.A.1.
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\314\ As noted in the following sections, we are finalizing some
updates to 40 CFR parts 1037, 1065, and 1068 to apply to other
sectors in addition to heavy-duty highway engines.
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A. Regulatory Useful Life
Useful life represents the period over which emission standards
apply for certified engines, and, practically, any difference between
the regulatory useful life and the generally longer operational life of
in-use engines represents miles and years of operation without an
assurance that emission standards will continue to be met. In addition
to promulgating new emission standards and promulgating new and
updating existing test procedures described in Section III, we are
updating regulatory useful life periods to further assure emission
performance of heavy-duty highway engines. In this section, we present
the updated regulatory useful life periods we are finalizing in this
rule. In Section IV.A.1, we present our revised useful life periods
that will apply for the new exhaust emission standards for criteria
pollutants, OBD, and requirements related to crankcase emissions. In
Section IV.A.2, we present the useful life periods that will apply for
the new refueling emission standards for certain Spark-ignition HDE. As
described in Section G.10 of this preamble, we are not finalizing the
proposed allowance for manufacturers to generate NOX
emissions credits from heavy-duty zero emissions vehicles (ZEVs) or the
associated useful life requirements.
1. Regulatory Useful Life Periods by Primary Intended Service Class
In this final rule, we are increasing the regulatory useful life
mileage values for new heavy-duty engines to better reflect real-world
usage, extend the emissions durability requirement for heavy-duty
engines, and improve long-term emission performance. In this Section
IV.1, we describe the regulatory useful life periods we are finalizing
for the four primary intended service classes for heavy-duty highway
engines.\315\ Our longer useful life periods vary by engine class to
reflect the different lengths of their estimated operational lives. As
described in the proposal for this rule, we continue to consider
operational life to be the average mileage at rebuild for CI engines
and the average mileage at replacement for SI engines.\316\
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\315\ The useful life periods we are finalizing in this rule
apply for criteria pollutant standards; we did not propose and are
not finalizing changes to the useful life periods that apply for GHG
standards.
\316\ See Chapter 2.4 of the RIA for a summary of the history of
our regulatory useful life provisions and our estimate of the
operational life for each heavy-duty engine class.
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In determining the appropriate longer useful life values to set in
the final rule, we retain our proposed objective to set useful life
periods that cover a significant portion of the engine's operational
life. However, as explained in the proposal, we also maintain that
[[Page 4360]]
the emission standards presented in Section III must be considered
together with their associated useful life periods. After further
consideration of the basis for the proposal, comments received,
supporting data available since the proposal, and the numeric level of
the final standards, we are selecting final useful life values within
the range of options proposed that cover a significant portion of the
engine's operational life and take into account the combined effect of
useful life and the final numeric standards on the overall stringency
and emissions reductions of the program. As described in the final RIA,
we concluded two engine test programs for this rule that demonstrated
technologies that are capable of meeting lower emission levels at much
longer mileages than current useful life periods. We evaluated a heavy-
duty diesel engine to a catalyst-aged equivalent of 800,000 miles for
the compression-ignition demonstration program, and a heavy-duty
gasoline engine to a catalyst-aged equivalent of 250,000 miles for the
spark-ignition demonstration program. As described in Section III of
this preamble, the results of those demonstration programs informed the
appropriate standard levels for the useful life periods we are
finalizing for each engine class. Our final useful life values were
also informed by comments, including additional information on
uncertainties and potential corresponding costs. We summarize key
comments in Section IV.1.ii, and provide complete responses to useful
life comments in section 3.8 of the Response to Comments document.
Our final useful life periods for Spark-ignition HDE, Light HDE,
Medium HDE, and Heavy HDE classes are presented in Table IV-1 and
specified in a new 40 CFR 1036.104(e).\317\ The final useful life
values that apply for Spark-ignition HDE, Light HDE, and Medium HDE
starting in MY 2027 match the most stringent option we proposed, that
is, MY 2031 step of proposed Option 1. The final useful life values for
Heavy HDE, which has a distinctly longer operational life than the
smaller engine classes, match the longest useful life mileage we
proposed for model year 2027 (i.e., the Heavy HDE mileage of proposed
Option 2). We are also increasing the years-based useful life from the
current 10 years to values that vary by engine class and match the
proposed value in the respective proposed option. After considering
comments, we are also adding hours-based useful life values to all
primary intended service classes based on a 20 mile per hour speed
threshold and the corresponding final mileage values.
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\317\ We are migrating the current alternate standards for
engines used in certain specialty vehicles from 40 CFR 86.007-11 and
86.008-10 into 40 CFR 1036.605 without modification. See Section
XI.B of this preamble for a discussion of these standards.
Table IV-1--Final Useful Life Periods by Primary Intended Service Class
--------------------------------------------------------------------------------------------------------------------------------------------------------
Current MY 2027 and later
Primary intended service class -----------------------------------------------------------------------------------------------
Miles Years Hours Miles Years Hours
--------------------------------------------------------------------------------------------------------------------------------------------------------
Spark-ignition HDE \a\.................................. 110,000 10 .............. 200,000 15 10,000
Light HDE \a\........................................... 110,000 10 .............. 270,000 15 13,000
Medium HDE.............................................. 185,000 10 .............. 350,000 12 17,000
Heavy HDE............................................... 435,000 10 22,000 650,000 11 32,000
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Current useful life period for Spark-ignition HDE and Light HDE for GHG emission standards is 15 years or 150,000 miles; we are not revising these
useful life periods in this final rule. See 40 CFR 1036.108(d).
For hybrid engines and powertrains, we are finalizing the proposal
that manufacturers certifying hybrid engines and powertrains would
declare the primary intended service class of their engine family using
40 CFR 1036.140. Once a primary intended service class is declared, the
engine configuration would be subject to the corresponding emission
standards and useful life values from 40 CFR 1036.104.
i. Summary of the Useful Life Proposal
For CI engines, the proposed Option 1 useful life periods included
two steps in MYs 2027 and 2031 that aligned with the final useful life
periods of CARB's HD Omnibus regulation, and the proposed MY 2031
periods covered close to 80 percent of the expected operational life of
CI engines based on mileage at out-of-frame rebuild. The useful life
mileages of proposed Option 2, which was a single-step option starting
in MY 2027, generally corresponded to the average mileages at which CI
engines undergo the first in-frame rebuild. The rebuild data indicated
that CI engines can last well beyond the in-frame rebuild mileages. We
noted in the proposal that it was unlikely that we would finalize a
single step program with useful life mileages shorter than proposed
Option 2; instead, we signaled that we would likely adjust the numeric
value of the standards to address any feasibility concerns.
For Spark-ignition HDE, the useful life mileage in proposed Option
1 was about 90 percent of the operational life of SI engines based on
mileage at replacement. The useful life of proposed Option 2 aligned
with the current SI engine useful life mileage that applies for GHG
standards. In the proposal, we noted that proposed Option 2 also
represented the lowest useful life mileage we would consider finalizing
for Spark-ignition HDE.
In proposed Option 1, we increased the years-based useful life
values for all engine classes to account for engines that accumulate
fewer miles annually. We also proposed to update the hours-based useful
life criteria for the Heavy HDE class to account for engines that
operated frequently, but accumulated relatively few miles due to lower
vehicle speeds. We calculated the proposed hours values by applying the
same 20 mile per hour conversion factor to the proposed mileages as was
applied when calculating the useful life hours that currently apply for
Heavy HDE.\318\ The proposed hours specification was limited to the
Heavy HDE class to be consistent with current regulations, but we
requested comment on adding hours-based useful life values to apply for
the other service classes.
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\318\ U.S. EPA, ``Summary and Analysis of Comments: Control of
Emissions of Air Pollution from Highway Heavy-Duty Engines'', EPA-
420-R-97-102, September 1997, pp 43-47.
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ii. Basis for the Final Useful Life Periods
In this Section IV.1.ii, we provide the rationale for our final
useful life periods, including summaries and responses to certain
comments that informed our final program. The complete set of useful
life comments
[[Page 4361]]
and our responses are in section 3.8 of the Response to Comments
document. As explained in the NPRM, CAA section 202(d) provides that
the minimum useful life for heavy-duty vehicles and engines is a period
of 10 years or 100,000 miles, whichever occurs first, and further
authorizes EPA to adopt longer useful life periods that we determine to
be appropriate.
Many commenters expressed general support for our proposal to
lengthen useful life periods in this rulemaking. Several commenters
expressed specific support for the useful life periods of proposed
Option 1 or proposed Option 2. Other commenters recommended EPA revise
the proposal to either lengthen or shorten the useful life periods to
values outside of the range of our proposed options.
We are lengthening the current useful life mileages to capture the
greatest amount of the operational life for each engine class that we
have determined is appropriate at this time. We disagree with
commenters recommending that we finalize useful life periods below the
mileages of proposed Option 2. As noted in our proposal, proposed
Option 2 represented the lower bound of useful life mileages we would
consider finalizing for all engine classes. Furthermore, as described
in Section III of this preamble and Chapter 3 of the RIA for this final
rule, both of EPA's engine test programs successfully demonstrated that
CI and SI engine technologies can achieve low emission levels at
mileages (800,000 miles and 250,000 miles, respectively) well beyond
Option 2. Even after taking into consideration uncertainties of the
impacts of variability and real world operation on emission levels at
the longest mileages, the test programs' data supports that mileages at
least as long as Option 2 are appropriate, and the final standards are
feasible at those mileages. We also disagree with commenters suggesting
we finalize mileages longer than proposed Option 1. We did not propose
and for the reasons just explained about impacts on emission level at
the longest mileages do not believe it is appropriate at this time to
require useful life periods beyond proposed Option 1.
Organizations submitting adverse comments on useful life focused
mostly on the useful life mileages proposed for the Heavy HDE service
class. Technology suppliers and engine manufacturers expressed concern
with the lack of data from engines at mileages well beyond the current
useful life. Suppliers commented that it could be costly and
challenging to design components without more information on component
durability, failure modes, and use patterns at high mileages. Engine
manufacturers claimed that some uncertainties relating to real world
use would limit the feasibility of the proposed Option 1 useful life
periods, including: The range of applications in which these engines
are used, variable operator behavior (including 2nd and 3rd owners),
and the use of new technology that is currently unproven in the field.
In Sections III and IV.F of this preamble, we describe other areas
where useful life plays a role and manufacturers expressed concern over
uncertainties, including certification, DF testing, engine rating
differences, lab-to-lab variability, production variability, and in-use
engine variability. Due to these combined uncertainties, manufacturers
stated that they expect to be conservative in their design and
maintenance strategies, and some may opt to schedule aftertreatment
replacement as a means to ensure compliance with new NOX
emission standards, particularly for proposed Option 1 numeric
standards and useful life values. Comments did not indicate a concern
that manufacturers may schedule aftertreatment replacement for the
smaller engine classes at the proposed Option 1 useful life periods.
We agree that there are uncertainties associated with implementing
new technology to meet new emission standards, and recognize that the
uncertainties are highest for Heavy HDE that are expected to have the
longest operational life and useful life periods. We acknowledge that
higher useful life mileage is one factor that may contribute to a risk
that manufacturers would schedule aftertreatment replacement to ensure
compliance for the heaviest engine class. Specific to Heavy HDE, the
final useful life mileage of 650,000 miles matches the longest useful
life mileage we proposed for model year 2027 and we expect
manufacturers have experience with their engines at this mileage
through their extended warranty offerings, thus reducing uncertainties
of real world operation compared to the longest useful life mileage we
proposed (i.e., 800,000 miles).\319\ For Heavy HDE, the final numeric
emission standards and useful life periods matching proposed Option 2,
combined with other test procedure revisions to provide clarity and
address variability, will require less conservative compliance
strategies than proposed Option 1 and will not require manufacturers to
plan for the replacement of the entire catalyst system. See Section III
for further discussion on the basis and feasibility of the final
emission standards.
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\319\ Brakora, Jessica. Memorandum to docket EPA-HQ-OAR-2019-
0055. ``Example Extended Warranty Packages for Heavy-duty Engines''.
September 29, 2022.
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Many commenters supported proposed Option 1, including useful life
periods out to 800,000 miles for the Heavy HDE class. Several
commenters pointed to EPA's engine testing results on an engine aged to
the equivalent of 800,000 miles as adequately demonstrating feasibility
of an 800,000-mile useful life for Heavy HDE. We agree that CI engines
are capable of meeting low emission levels at very high mileages in a
controlled laboratory environment, but manufacturer liability for
maintaining certified emission levels over the regulatory useful life
period is not restricted to laboratory tests. Manufacturers expressed
specific concern about the uncertainties outside the controlled
laboratory environment after an engine enters commerce. In Sections III
and IV.F of this preamble we summarize comments relating to how useful
life factors into certification, DF testing, and in-use testing. In
Section III.B, we describe a certification requirement we are
finalizing for manufacturers to demonstrate the emission controls on
Heavy HDE are durable through the equivalent of 750,000 miles; this
durability demonstration will extend beyond the 650,000 mile useful
life period for these engines. We expect this extended laboratory-based
demonstration, in a controlled environment, will translate to greater
assurance that an engine will maintain its certified emission levels in
real world operation where conditions are more variable throughout the
regulatory useful life. This greater assurance would be achieved while
minimizing the compliance uncertainties identified by manufacturers in
comments for the highest proposed useful life mileages.
We believe manufacturers can adequately ensure the durability of
their smaller engines over useful life periods that match proposed
Option 1 both for meeting emission standards in the laboratory at
certification and in the laboratory and applicable in-use testing after
operation in the real world. The final durability demonstration
requirements for Spark-ignition HDE, Light HDE, and Medium HDE match
the final useful life periods for those smaller engines classes.
As shown in Table IV-1, we are also finalizing useful life periods
in years and hours for all primary intended service classes. We are
updating the years values from the current 10 years to 15 years for
Spark-ignition HDE and
[[Page 4362]]
Light HDE, 12 years for Medium HDE, and 11 years for Heavy HDE. The
final years values match the years values we proposed and vary by
engine class corresponding to the proposed mileage option we are
finalizing. We are also adding hours as a useful life criteria for all
engine classes. We received no adverse comments for hours-based useful
life periods and are finalizing hours values by applying a 20-mph
conversion factor, as proposed, to calculate hours values from the
final mileage values.
We have finalized a combination of emissions standards and useful
life values that our analysis and supporting data demonstrate are
feasible for all heavy-duty engine classes. We are lengthening the
existing useful life mileages to capture the greatest amount of the
operational life for each engine class that we have determined is
appropriate at this time, while considering the impact of useful life
length on the stringency of the standards and other requirements of
this final rule. Preamble Section III describes how our analysis and
the EPA engine test programs demonstrated feasibility of the standards
at these useful life values, including data on emission levels at the
equivalent useful life mileages.
2. Useful Life for Incomplete Vehicle Refueling Emission Standards
As described in Section III.E., we are finalizing a refueling
emission standard for incomplete vehicles above 14,000 lb GVWR.
Manufacturers would meet the refueling emission standard by installing
onboard refueling vapor recovery (ORVR) systems on these incomplete
vehicles. Since ORVR systems are based on the same carbon canister
technology that manufacturers currently use to control evaporative
emissions on these incomplete vehicles, we proposed to align the useful
life periods for the two systems. In 40 CFR 1037.103(f), we are
finalizing a useful life of 15 years or 150,000 miles, whichever comes
first, for refueling standards for incomplete vehicles above 14,000 lb
GVWR, as proposed.
Evaporative emission control systems are currently part of the fuel
system of incomplete vehicles, and manufacturers are meeting applicable
standards and useful life requirements for evaporative systems today.
ORVR is a mature technology that has been installed on complete
vehicles for many years, and incomplete vehicle manufacturers have
experience with ORVR systems through their complete vehicle
applications. Considering the manufacturers' experience with
evaporative emission standards for incomplete vehicles, and their
familiarity with ORVR systems, we continue to believe it would be
feasible for manufacturers to apply the same evaporative emission
standard useful life periods to refueling standards. We received no
adverse comments relating to the proposed 15 years/150,000 miles useful
life for refueling standards, and several manufacturers commented in
support of our proposed periods.
B. Ensuring Long-Term In-Use Emissions Performance
In the proposal, we introduced several ideas for an enhanced,
comprehensive strategy to ensure in-use emissions performance over more
of an engine's operational life. In this section, we discuss the final
provisions to lengthen emission-related warranty periods, update
maintenance requirements, and improve serviceability in this rule.
Taken together, these updates are intended to increase the likelihood
that engine emission controls will be maintained properly through more
of the service life of heavy-duty engines and vehicles, including
beyond useful life.
1. Emission-Related Warranty
The emission-related warranty period is the period over which CAA
section 207 requires an engine manufacturer to warrant to a purchaser
that the engine is designed, built, and equipped so as to conform with
applicable regulations under CAA section 202 and is free from defects
in materials or workmanship which would cause the engine not to conform
with applicable regulations for the warranty period. If an emission-
related component fails during the regulatory emission warranty period,
the manufacturer is required to pay for the cost of repair or
replacement. A manufacturer's general emissions warranty
responsibilities are currently set out in 40 CFR 1068.115. Note that
while an emission warranty provides protection to the owner against
emission-related repair costs during the warranty period, the owner is
responsible for properly maintaining the engine (40 CFR 1068.110(e)),
and the manufacturer may deny warranty claims for failures that have
been caused by the owner's or operator's improper maintenance or use
(40 CFR 1068.115(a)).
In this section, we present the updated emission-related warranty
periods we are finalizing for heavy-duty highway engines and vehicles
included in this rule. As described in Section G.10 of this preamble,
we are not finalizing the proposed allowance for manufacturers to
generate NOX emissions credits from heavy-duty zero
emissions vehicles (ZEVs) or the associated warranty requirements.
i. Final Warranty Periods by Primary Intended Service Class
We are updating and significantly strengthening our emission-
related warranty periods for model year 2027 and later heavy-duty
engines.\320\ We are finalizing most of the emission-related warranty
provisions of 40 CFR 1036.120 as proposed. Following our approach for
useful life, we are revising the proposed warranty periods for each
primary intended service class to reflect the difference in average
operational life of each class and after considering additional
information provided by commenters. See section 4 of the Response to
Comments document for our detailed responses, including descriptions of
revisions to the proposed regulatory text in response to commenter
requests for clarification.
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\320\ Emission-related components for only criteria pollutant
emissions or both greenhouse gas (i.e., CO2, N2O, and CH4) and
criteria pollutant emissions would be subject to the final warranty
periods of 40 CFR 1036.120. See 40 CFR 1036.150(w).
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EPA's current emissions-related warranty periods for heavy-duty
engines range from 22 percent to 54 percent of the current regulatory
useful life; the warranty periods have not changed since 1983 even as
the useful life periods were lengthened.\321\ The revised warranty
periods are expected to result in better engine maintenance and less
tampering, which would help to maintain the benefits of the emission
controls. In addition, longer regulatory warranty periods may lead
engine manufacturers to simplify repair processes and make them more
aware of system defects that need to be tracked and reported to EPA.
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\321\ The useful life for heavy heavy-duty engines was increased
from 290,000 miles to 435,000 miles for 2004 and later model years
(62 FR 54694, October 21, 1997).
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Our final emission-related warranty periods for heavy-duty engines
are presented in Table IV-2 and specified in a new 40 CFR
1036.120.322 323 The final warranty mileages that apply
starting in MY 2027 for Spark-ignition HDE, Light HDE, and Medium HDE
match the longest warranty mileages proposed (i.e., MY 2031 step of
proposed Option 1) for these primary intended service
[[Page 4363]]
classes. For Heavy HDE, the final warranty mileage matches the longest
warranty mileage proposed for MY 2027 (i.e., MY 2027 step of proposed
Option 1). We are also increasing the years-based warranty from the
current 5 years to 10 years for all engine classes. After considering
comments, we are also adding hours-based warranty values to all primary
intended service classes based on a 20 mile per hour speed threshold
and the corresponding final mileage values. Consistent with current
warranty provisions, the warranty period would be whichever warranty
value (i.e., mileage, hours, or years) occurs first. We summarize key
comments in Section IV.B.1.i.a, and provide complete responses to
warranty comments in section 4 of the Response to Comments document.
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\322\ All engines covered by a primary intended service class
would be subject to the corresponding warranty period, regardless of
fuel used.
\323\ We are migrating the current alternate standards for
engines used in certain specialty vehicles from 40 CFR 86.007-11 and
86.008-10 into 40 CFR 1036.605 without modifying those alternate
standards, as proposed. See Section XI.B of this preamble for a
discussion of these standards.
Table IV-2--Final Emission-Related Warranty Periods by Primary Intended Service Class
--------------------------------------------------------------------------------------------------------------------------------------------------------
Current Model year 2027 and later
Primary intended service class -----------------------------------------------------------------------------------------------
Mileage Years Hours Mileage Years Hours
--------------------------------------------------------------------------------------------------------------------------------------------------------
Spark-Ignition HDE...................................... 50,000 5 .............. 160,000 10 8,000
Light HDE............................................... 50,000 5 .............. 210,000 10 10,000
Medium HDE.............................................. 100,000 5 .............. 280,000 10 14,000
Heavy HDE............................................... 100,000 5 .............. 450,000 10 22,000
--------------------------------------------------------------------------------------------------------------------------------------------------------
We note that we are finalizing as proposed that when a
manufacturer's certified configuration includes hybrid system
components (e.g., batteries, electric motors, and inverters), those
components are considered emission-related components, which would be
covered under the warranty requirements in new 40 CFR 1036.120.\324\
Similar to the approach for useful life in Section IV.A, a manufacturer
certifying a hybrid engine or hybrid powertrain would declare a primary
intended service class for the engine family and apply the
corresponding warranty periods in 40 CFR 1036.120 when certifying the
engine configuration.\325\ This approach to clarify that hybrid
components are part of the broader engine configuration provides
vehicle owners and operators with consistent warranty coverage based on
the intended vehicle application.
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\324\ See our new definition of ``emission-related component''
in 40 CFR 1036.801. Defects or failures of hybrid system components
can result in the engine operating more, and thus increase
emissions.
\325\ As described in 40 CFR 1036.140, the primary intended
service classes are partially based on the GVWR of the vehicle in
which the configuration is intended to be used. See also the update
to definition of ``engine configuration'' in 40 CFR 1036.801 to
clarify that an engine configuration would include hybrid components
if it is certified as a hybrid engine or hybrid powertrain.
---------------------------------------------------------------------------
We estimated the emissions impacts of the final warranty periods in
our inventory analysis, which is summarized in Section VI and discussed
in detail in Chapter 5 of our RIA. In Section V, we estimate costs
associated with the final warranty periods, including indirect costs
for manufacturers and operating costs for owners and operators.
a. Summary of the Emission-Related Warranty Proposal
In the proposal, we included several justifications for lengthened
warranty periods that continue to apply for the final provisions.
First, we expected longer emission-related warranty periods would lead
owners to continue maintain their engines and vehicles over a longer
period of time and ensure longer-term benefits of emission
controls.\326\ Since emission-related repairs would be covered by
manufacturers for a longer period of time, an owner would be more
likely to have systems repaired and less likely to tamper to avoid the
cost of a repair.\327\
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\326\ See Chapter 5 of the RIA for a discussion of mal-
maintenance and tampering effects in our emission inventory
estimates.
\327\ Existing warranty provisions specify that owners are
responsible for properly maintaining their engines (40 CFR
1068.110(e)) and manufacturers may deny warranty claims for failures
that have been caused by the owner's or operator's improper
maintenance or use (40 CFR 1068.115(a)). See Section IV.B.2 for a
description of updates to the allowable maintenance provisions.
---------------------------------------------------------------------------
Second, emission-related repair processes may get more attention
from manufacturers if they are responsible for repairs over a longer
period of time. The current, relatively short warranty periods provide
little incentive for manufacturers to evaluate the complexity of their
repair processes, since the owner pays for the repairs after the
warranty period ends. As manufacturers try to remain competitive,
longer emission warranty periods may lead manufacturers to simplify
repair processes and provide better training to technicians in an
effort to reduce their warranty repair costs. Simplifying repair
processes could include modifying emission control components in terms
of how systems are serviced and how components are replaced (e.g.,
modular sub-assemblies that could be replaced individually, resulting
in a quicker, less expensive repair). Improved technician training may
also reduce warranty repair costs by improving identification and
diagnosing component failures more quickly and accurately, thus
reducing downtime for owners and avoiding repeated failures,
misdiagnoses of failures, and higher costs from repeat repair events at
service facilities.
Finally, longer regulatory emission warranty periods would increase
the period over which the engine manufacturer would be made aware of
emission-related defects. Manufacturers are currently required to track
and report defects to the Agency under the defect reporting provisions
of 40 CFR part 1068. Under 40 CFR 1068.501(b), manufacturers
investigate possible defects whenever a warranty claim is submitted for
a component. Therefore, manufacturers can easily monitor defect
information from dealers and repair shops who are performing those
warranty repair services, but after the warranty period ends, the
manufacturer would not necessarily know about these events, since
repair facilities are less likely to be in contact with the
manufacturers and they are less likely to use OEM parts. A longer
warranty period would allow manufacturers to have access to better
defect information over a period of time more consistent with engine
useful life.
In the proposal, we also highlighted that a longer warranty period
would encourage owners of vehicles powered by SI engines (as for CI
engines) to follow manufacturer-prescribed maintenance procedures for a
longer period of time, as failure to do so would void the warranty. We
noted that the impact of a longer emissions warranty period may be
slightly different for SI engines from a tampering perspective. Spark-
ignition engine systems rely on mature technologies, including
evaporative emission systems and three-way catalyst-based emission
controls, that have been consistently reliable for light-duty and
heavy-duty vehicle
[[Page 4364]]
owners.\328\ SI engine owners may not currently be motivated to tamper
with their catalyst systems to avoid repairs, but they may purchase
defeat devices intended to disable emission controls to boost the
performance of their engines. We expected SI engine owners may be less
inclined to install such defeat devices during a longer warranty
period.
---------------------------------------------------------------------------
\328\ The last U.S. EPA enforcement action against a
manufacturer for three-way catalysts was settled with
DaimlerChrylser Corporation Settlement on December 21, 2005.
Available online: https://www.epa.gov/enforcement/daimlerchrysler-corporation-settlement.
---------------------------------------------------------------------------
We proposed two options that generally represented the range of
revised emission warranty periods we considered adopting in the final
rule. Proposed Option 1 included warranty periods that aligned with the
MY 2027 and MY 2031 periods of the CARB HD Omnibus program and were
close to 80 percent of useful life. At the time of the proposal, we
assumed most manufacturers would continue to certify 50-state compliant
engines in MY 2027 and later, and it would simplify the certification
process if there would be consistency between CARB and Federal
requirements. The warranty periods of proposed Option 2 were proposed
to apply in a single step beginning in model year 2027 and to match
CARB's Step 1 warranty periods for engines sold in California.\329\ The
proposed Option 2 mileages covered 40 to 55 percent of the proposed
Option 1 MY 2031 useful life mileages and represented an appropriate
lower end of the range of the revised regulatory emission warranty
periods we considered.
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\329\ Since the CARB Step 1 warranty program did not include
updates to warranty for SI engines, the proposed Option 2 warranty
mileage for that the Spark-ignition HDE class matched the current
useful life for those engines, consistent with the approach for
Light HDE proposed Option 2 warranty.
---------------------------------------------------------------------------
While we noted that a majority of engines would reach the warranty
mileage in a reasonable amount of time, some applications may have very
low annual mileage due to infrequent use or low speed operation and may
not reach the warranty mileage for many years. To ensure manufacturers
are not indefinitely responsible for components covered under emissions
warranty in these situations, we proposed to revise the years-based
warranty periods and proposed hours-based warranty periods for all
engine classes in proposed Option 1.
For the years-based period, which would likely be reached first by
engines with lower annual mileage due to infrequent use, we proposed to
increase the current period from 5 years to 7 years for MY 2027 through
2030, and to 10 years starting with MY 2031. We also proposed to add an
hours-based warranty period to cover engines that operate at low speed
and/or are frequently in idle mode.\330\ In contrast to infrequent use,
low speed and frequent idle operation can strain emission control
components. We proposed an hours-based warranty period to allow
manufacturers to factor gradually-accumulated work into their warranty
obligations.
---------------------------------------------------------------------------
\330\ We proposed warranty hours for all primary intended
service classes based on a 20 mile per hour average vehicle speed
threshold to convert from the proposed mileage values.
---------------------------------------------------------------------------
b. Basis for the Final Emission-Related Warranty Periods
As detailed in section 4 of the Response to Comments document for
this rule, commenter support for lengthening emission-related warranty
periods varied. Many commenters expressed general support for our
proposal to lengthen warranty periods in this rulemaking. Several
commenters expressed specific support for the warranty periods of
proposed Option 1 or proposed Option 2. Other commenters recommended
EPA revise the proposal to either lengthen or shorten the warranty
periods to values outside of the range of our proposed options.
Our final warranty periods continue to be influenced by the
potential beneficial outcomes of lengthening emission-related warranty
periods that we discussed in the proposal. Specifically, we continue to
believe lengthened warranty periods will effectively assure owners
properly maintain and repair their emission controls over a longer
period, reduce the likelihood of tampering, provide additional
information on failure modes, and create a greater incentive for
manufacturers to simplify repair processes to reduce costs. Several
commenters agreed with our list of potential outcomes, with some noting
that any associated emissions benefits would be accelerated by pulling
ahead the warranty periods of the MY 2031 step of proposed Option 1 to
begin in MY 2027.
Organizations submitting adverse comments on lengthening warranty
periods focused mostly the warranty mileages proposed for the Heavy HDE
service class. Technology suppliers and engine manufacturers expressed
concern with the lack of data from engines at high mileages, including
uncertainties related to frequency and cause of failures, varying
vehicle applications, and operational changes as the engine ages. We
considered commenters' concerns regarding how uncertainties for the
highest mileages of proposed Option 1 could cause manufacturers to
respond by conservatively estimating their warranty cost. We continue
to expect, as noted in the proposal, that manufacturers are likely to
recoup the costs of warranty by increasing the purchase price of their
products. We agree with comments indicating that increases in purchase
price can increase the risk of pre-buy or low-buy, especially for the
heaviest engine class, Heavy HDE.
As described in this section, the final warranty periods are within
the range of periods over which we expect manufacturers have access to
failure data, which should limit the need for manufacturers to
conservatively estimate warranty costs. We summarize our updated cost
and economic impact analyses, which reflect the final warranty periods,
in Sections V and X of this preamble, respectively. For more
information, see our complete assessments of costs in Chapter 7 and
economic impacts in Chapter 10 of the Regulatory Impact Analysis for
this final rule.
We retain our proposed objectives to lengthen warranty periods to
cover a larger portion of the operational lives and to be more
consistent with the final useful life periods. Similar to our approach
for the useful life mileages in this final rule (see Section IV.A of
this preamble), we believe it is appropriate to pull ahead the longest
proposed MY 2031 warranty periods to apply in MY 2027 for the smaller
engine classes. For Spark-ignition HDE, Light HDE, and Medium HDE, the
final warranty mileages are 160,000 miles, 210,000 miles, and 280,000
miles, respectively, which cover about 80 percent of the corresponding
final useful life mileages. In response to commenters concerned with
data limitations, we expect any component failure and wear data
available from engines in the largest engine class would be applicable
to the smaller engine classes. As such, manufacturers and suppliers
have access to failure and wear data at the mileages we are finalizing
for the smaller engine classes through their current R&D and in-use
programs evaluating components for larger engines that currently have a
435,000 mile useful life.
We are not applying the same pull-ahead approach for the Heavy HDE
warranty mileage. We do not believe it is appropriate at this time to
finalize a 600,000-mile warranty for the Heavy HDE class that would
uniquely cover greater than 90 percent of the 650,000-
[[Page 4365]]
mile final useful life, especially considering the comments pointing to
uncertainties, lack of data, and potential high costs specific to Heavy
HDE. We are also not applying the approach of adopting the warranty
mileage of proposed Option 2, as was done for Heavy HDE useful life, as
we do not believe the proposed Option 2 warranty of 350,000 miles would
provide emission control assurance over a sufficient portion of the
useful life. Instead, we are finalizing a warranty mileage that matches
the longest mileage proposed for MY 2027 (450,000 miles), covering a
percentage of the final useful life that is more consistent with the
warranty periods of the smaller engine classes. The final warranty
mileage for Heavy HDE is only 15,000 miles longer than the current
useful life for this engine class. As noted for the warranties of the
smaller engine classes, we expect manufacturers and suppliers have
access to failure data nearing 450,000 miles through their R&D programs
evaluating Heavy HDE over their current useful life. We expect
manufacturers also have experience with their engines at this mileage
through their extended warranty offerings; thus, they already possess
real world operational data in addition to their internal
evaluations.\331\
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\331\ Brakora, Jessica. Memorandum to docket EPA-HQ-OAR-2019-
0055. ``Example Extended Warranty Packages for Heavy-duty Engines''.
September 29, 2022.
---------------------------------------------------------------------------
Several organizations commented on the proposed years or hours
criteria for warranty. One supplier noted that analyses focused on
tractors and their relatively high mileages may not accurately predict
the use of vocational vehicles that are more limited by hours of
operation. The same supplier suggested EPA should further differentiate
warranties by vehicles classes and vocations. Another organization
cautioned against warranty periods that are one-size-fits-all. Two
organizations supported applying an hours-based warranty period for all
engine classes to cover lower-speed applications and the 20-mph
conversion factor that we proposed.
We agree that vocational vehicles have distinct use patterns;
however, we did not propose and are not finalizing warranty periods at
the vehicle level to distinguish between vehicle types in this rule. We
are finalizing three warranty thresholds for each heavy-duty engine
class: A mileage threshold that is likely to reached first by vehicles
driving many miles annually, a years threshold that is likely to be
reached first by vehicles that drive infrequently or seasonally, and an
hours threshold that is likely to be reached first by vehicles that
drive frequently at lower speeds or with significant idling. We believe
adding an hours threshold in the final rule to the mileage- and years-
based warranty periods for all engine classes will lead to more
equitable warranty obligations across the range of possible vehicle
applications for which a heavy-duty engine may be used.
ii. Warranty for Incomplete Vehicle Refueling Emission Controls
As noted in Section III.E, we are finalizing refueling emission
standards for Spark-ignition HDE that are certified as incomplete
vehicles above 14,000 lb GVWR.\332\ Our refueling standards are
equivalent to the refueling standards that are in effect for light- and
heavy-duty complete Spark-ignition HDVs. We project manufacturers would
meet the new refueling standards by adapting the existing onboard
refueling vapor recovery (ORVR) systems from systems designed for
complete vehicles. The new ORVR systems will likely supplement existing
evaporative emission control systems installed on these vehicles.
---------------------------------------------------------------------------
\332\ See the final updates to 40 CFR 1037.103.
---------------------------------------------------------------------------
We are finalizing warranty periods for the ORVR systems of
incomplete vehicles above 14,000 lb GVWR that align with the current
warranty periods for the evaporative systems on those vehicles.
Specifically, warranty periods for refueling emission controls would be
5 years or 50,000 miles on incomplete Light HDV, and 5 years or 100,000
miles on incomplete Medium HDV and Heavy HDV, as proposed. See our
final updates to 40 CFR 1037.120. Our approach to apply the existing
warranty periods for evaporative emission control systems to the ORVR
systems is similar to our approach to the final regulatory useful life
periods associated with our final refueling standards discussed in
Section IV.A. We received no adverse comments on our proposed warranty
periods for refueling emission controls.
2. Maintenance
In this section, we describe the migrated and updated maintenance
provisions we are finalizing for heavy-duty highway engines. Section
IV.F of this preamble summarizes the current durability demonstration
requirements and our final updates.
Our final maintenance provisions, in a new section 40 CFR 1036.125,
combine and amend the existing criteria pollutant maintenance
provisions from 40 CFR 86.004-25 and 86.010-38. Similar to other part
1036 sections we are adding in this rule, the structure of the new 40
CFR 1036.125 is consistent with the maintenance sections in the
standard-setting parts of other sectors (e.g., nonroad compression-
ignition engines in 40 CFR 1039.125). In 40 CFR 1036.205(i), we are
codifying the current manufacturer practice of including maintenance
instructions in their application for certification such that approval
of those instructions would be part of a manufacturer's certification
process.\333\ We are also finalizing a new paragraph 40 CFR 1036.125(h)
outlining several owner's manual requirements, including migrated and
updated provisions from 40 CFR 86.010-38(a).
---------------------------------------------------------------------------
\333\ The current submission of maintenance instructions
provisions in 40 CFR 86.079-39 are migrated into the requirements
for an application for certification provisions in 40 CFR 1036.205.
---------------------------------------------------------------------------
This section summarizes the final provisions that clarify the types
of maintenance, update the options for demonstrating critical emission-
related maintenance will occur and the minimum scheduled maintenance
intervals for certain components, and specify the requirements for
maintenance instructions. The proposed rule provided an extensive
discussion of the rationale and information supporting the proposed
maintenance provisions (87 FR 17520, March 28, 2022). See also section
6 of the Response to Comments for a detailed discussion of the comments
and how they may have informed changes we are making to the proposal in
this final rule.
i. Types of Maintenance
The new 40 CFR 1036.125 clarifies that maintenance includes any
inspection, adjustment, cleaning, repair, or replacement of components
and, consistent with 40 CFR 86.004-25(a)(2), broadly classifies
maintenance as emission-related or non-emission-related and scheduled
or unscheduled.\334\ As proposed, we are finalizing five types of
maintenance that manufacturers may choose to schedule: Critical
emission-related maintenance, recommended additional maintenance,
special maintenance, noncritical emission-related maintenance, and non-
emission-related maintenance. As we explained in the proposal,
identifying and defining these maintenance categories in final 40 CFR
1036.125 distinguishes between the types of maintenance manufacturers
may choose to recommend to owners in
[[Page 4366]]
maintenance instructions, identifies the requirements that apply to
maintenance performed during certification durability demonstrations,
and clarifies the relationship between the different types of
maintenance, emissions warranty requirements, and in-use testing
requirements. The final provisions thus also specify the conditions for
scheduling each of these five maintenance categories.
---------------------------------------------------------------------------
\334\ We include repairs as a part of maintenance because proper
maintenance would require owners to repair failed or malfunctioning
components. We note that repairs are considered unscheduled
maintenance that would not be performed during durability testing
and may be covered under warranty.
---------------------------------------------------------------------------
We summarize several revisions to the proposed critical emission-
related maintenance provisions in Section 0 with additional details in
section 6 of the Response to Comments document. As proposed, the four
other types of maintenance will require varying levels of EPA approval.
In 40 CFR 1036.125(b), we propose to define recommended additional
maintenance as maintenance that manufacturers recommend owners perform
for critical emission-related components in addition to what is
approved for those components under 40 CFR 1036.125(a). We are
finalizing this provision as proposed except for a clarification in
wording to connect additional recommended maintenance and critical
emission-related maintenance more clearly. Under the final provisions,
a manufacturer may recommend that owners replace a critical emission-
related component at a shorter interval than the manufacturer received
approval to schedule for critical emission-related maintenance;
however, the manufacturer will have to clearly distinguish their
recommended intervals from the critical emission-related scheduled
maintenance in their maintenance instructions. As described in this
Section III.B.2 and the proposal, recommended additional maintenance is
not performed in the durability demonstration and cannot be used to
deny a warranty claim, so manufacturers will not be limited by the
minimum maintenance intervals or need the same approval from EPA by
demonstrating the maintenance would occur.
In 40 CFR 1036.125(c), we proposed that special maintenance would
be more frequent maintenance approved at shorter intervals to address
special situations, such as atypical engine operation. We received one
comment requesting we clarify special maintenance in proposed 40 CFR
1036.125(c) and we are finalizing this provision as proposed except
that we are including an example of biodiesel use in the final
paragraph (c). Under the final provisions, manufacturers will clearly
state that the maintenance is associated with a special situation in
the maintenance instructions provided to EPA and owners.
In 40 CFR 1036.125(d), as proposed, we are finalizing that
noncritical emission-related maintenance includes inspections and
maintenance that is performed on emission-related components but is
considered ``noncritical'' because emission control will be unaffected
(consistent with existing 40 CFR 86.010-38(d)). Under this final
provision, manufacturers may recommend noncritical emission-related
inspections and maintenance in their maintenance instructions if they
clearly state that it is not required to maintain the emissions
warranty.
In 40 CFR 1036.125(e), we are updating the paragraph heading from
nonemission-related maintenance to maintenance that is not emission-
related to be consistent with other sectors. The final provision, as
proposed, describes the maintenance as unrelated to emission controls
(e.g., oil changes) and states that manufacturers' maintenance
instructions can include any amount of maintenance unrelated to
emission controls that is needed for proper functioning of the engine.
Critical Emission-Related Components
Consistent with the existing and proposed maintenance provisions,
the final provisions continue to distinguish certain components as
critical emission-related components. The proposal did not migrate the
specific list of components defined as ``critical emission-related
components'' from 40 CFR 86.004-25(b)(6)(i); instead, we proposed and
are finalizing that manufacturers identify their specific critical
components by obtaining EPA's approval for critical emission-related
maintenance using 40 CFR 1036.125(a). Separately, we also proposed a
new definition for critical emission-related components in 40 CFR
1068.30 and are finalizing with revision. The final definition is
consistent with paragraph 40 CFR 86.004-25(b)(6)(i)(I) and the current
paragraph IV of 40 CFR part 1068, appendix A, as proposed.\335\ We are
removing the proposed reference to 40 CFR 1068, appendix A, in the
final definition, since appendix A specifies emission-related
components more generally. To avoid having similar text in two
locations, we are also replacing the current text of paragraph IV of 40
CFR 1068, appendix A, with a reference to the new part 1068 definition
of critical emission-related components.
---------------------------------------------------------------------------
\335\ Paragraph (b)(6)(i)(I) concludes the list of critical
emission-related components in 40 CFR 86.004-25 with a general
description stating: ``Any other component whose primary purpose is
to reduce emissions or whose failure would commonly increase
emissions of any regulated pollutant without significantly degrading
engine performance.'' The existing paragraph (IV) of 40 CFR 1068,
appendix A similarly states: ``Emission-related components also
include any other part whose primary purpose is to reduce emissions
or whose failure would commonly increase emissions without
significantly degrading engine/equipment performance.''
---------------------------------------------------------------------------
ii. Critical Emission-Related Maintenance
A primary focus of the final maintenance provisions is critical
emission-related maintenance. Critical emission-related maintenance
includes any adjustment, cleaning, repair, or replacement of emission-
related components that manufacturers identify as having a critical
role in the emission control of their engines. The final 40 CFR
1036.125(a), consistent with current maintenance provisions in 40 CFR
part 86 and the proposal, will continue to allow manufacturers to seek
advance approval from EPA for new emission-related maintenance they
wish to include in maintenance instructions and perform during
durability demonstration. The final 40 CFR 1036.125(a) retains the same
proposed structure that includes a maintenance demonstration and
minimum maintenance intervals, and a pathway for new technology that
may be applied in engines after model year 2020.
We are finalizing with revision the maintenance demonstration
proposed in 40 CFR 1036.125(a)(1). The final provision includes the
five proposed options for manufacturers to demonstrate the maintenance
is reasonably likely to be performed in-use, with several clarifying
edits detailed in the Response to Comments document .\336\ As further
discussed in Section IV.D, we are finalizing the separate statement in
40 CFR 1036.125(a)(1) that points to the final inducement provisions,
noting that we will accept DEF replenishment as reasonably likely to
occur if an engine meets the specifications in proposed 40 CFR
1036.111; we are not setting a minimum maintenance interval for DEF
replenishment. Also, as noted in the proposal and reiterated here, the
first maintenance demonstration option, described in 40 CFR
1036.125(a)(1)(i), is intended to cover emission control technologies
that have an inherent performance degradation that coincides with
emission increases, such as back pressure resulting from a clogged DPF.
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\336\ The five maintenance demonstration options are consistent
with current maintenance demonstration requirements in 40 CFR
86.004-25 and 86.094-25.
---------------------------------------------------------------------------
Consistent with the current and proposed maintenance provisions, we
are specifying minimum maintenance
[[Page 4367]]
intervals for certain emission-related components, such that
manufacturers may not schedule more frequent maintenance than we allow.
In 40 CFR 1036.125(a)(2), we are updating the list of components with
minimum maintenance intervals to more accurately reflect components in
use today and extending the replacement intervals such that they
reflect replacement intervals currently scheduled for those components.
See the NPRM preamble for a discussion of our justification for
terminology changes we are applying in the final rule, and the list of
components that we are not migrating from 40 CFR part 86 because they
are obsolete or covered by other parts.
Consistent with current maintenance provisions, we proposed to
disallow replacement of catalyst beds and particulate filter elements
within the regulatory useful life of the engine.\337\ We are removing
reference to catalyst beds and particular filter elements in the
introductory text of paragraph (a)(2) and instead are adding them, with
updated terminology, as a separate line in the list of components in
Table 1 of 40 CFR 1036.125(a)(2) with minimum maintenance intervals
matching the final useful life values of this rule.\338\ Including
catalyst substrates and particulate filter substrates directly in the
table of minimum maintenance intervals more clearly connects the
intervals to the useful life values. In response to manufacturer
comments requesting clarification, we are also adding a reference to 40
CFR 1036.125(g) in paragraph (a)(2) to clarify that manufacturers are
not restricted from scheduling maintenance more frequent than the
minimum intervals, including replacement of catalyst substrates and
particulate filter substrates, if they pay for it.
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\337\ Existing 40 CFR 86.004-25(b)(4)(iii) states that only
adjustment and cleaning are allowed for catalyst beds and
particulate filter elements and that replacement is not allowed
during the useful life. Existing 40 CFR 86.004 25(i) clarifies that
these components could be replaced or repaired if manufacturers
demonstrate the maintenance will occur and the manufacturer pays for
it.
\338\ In the final provision, we replaced ``catalyst bed'' with
``catalyst substrate'' and ``particulate filter element'' with
``particulate filter substrate''.
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We are finalizing as proposed the addition of minimum intervals for
replacing hybrid system components in engine configurations certified
as hybrid engines or hybrid powertrains, which would include the
rechargeable energy storage system (RESS). Our final minimum intervals
for hybrid system components equal the current useful life for the
primary intended service classes of the engines that these electric
power systems are intended to supplement or replace.\339\
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\339\ We note that Table IV-3 and the corresponding Table 1 of
40 CFR 1036.125(a)(2) include a reference to ``hybrid system
components'', which we inadvertently omitted from the tables in the
proposed rule.
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Table IV-3 summarizes the minimum replacement intervals we are
finalizing in a new table in 40 CFR 1036.125(a)(2). As explained in the
proposal, we believe it is appropriate to account for replacement
intervals that manufacturers have already identified and demonstrated
will occur for these components and the final replacement intervals
generally match the shortest mileage interval (i.e., most frequent
maintenance) of the published values, with some adjustments after
considering comments. Commenters noted that some sensors are not
integrated with a listed system and requested EPA retain a discrete set
of minimum intervals for sensors, actuators, and related ECMs. We agree
and are specifying minimum intervals that match the current intervals
for sensors, actuators, and related control modules that are not
integrated into other systems. We are retaining the proposed text to
indicate that intervals specified for a given system would apply for
all to actuators, sensors, tubing, valves, and wiring associated with
that component associated with that system. We are also revising the
minimum intervals for ignition wires from the proposed 100,000 miles to
50,000 miles to match the current intervals and adding an interval for
ignition coils at the same 50,000 miles after considering comments. See
section 6 of the Response to Comments document for other comments we
considered when developing the final maintenance provisions.
We proposed to retain the maintenance intervals specified in 40 CFR
86.004-25 for adjusting or cleaning components as part of critical
emission-related maintenance. We are finalizing the proposed
maintenance intervals for adjusting and cleaning with one correction.
Commenters noted that the proposal omitted an initial minimum interval
for adjusting or cleaning EGR system components. Consistent with 40 CFR
86.004-25(b), we are correcting the proposed intervals for several
components (catalyst system components, EGR system components (other
than filters or coolers), particulate filtration system components, and
turbochargers) from 150,000 miles or 4,500 hours to include an initial
interval of 100,000 miles or 3,000 hours, with subsequent intervals of
150,000 miles or 4,500 hours. We did not reproduce the new Table 2 from
40 CFR 1036.125(a)(2) showing the minimum intervals for adjusting or
cleaning components in this preamble.
Table IV-3--Minimum Scheduled Maintenance Intervals in Miles (or Hours) for Replacing Critical Emission-Related
Components in 40 CR 1036.125
----------------------------------------------------------------------------------------------------------------
Spark-ignition
Components HDE Light HDE Medium HDE Heavy HDE
----------------------------------------------------------------------------------------------------------------
Spark plugs............................. 25,000 (750) ................ ................ ................
DEF filters............................. ................ 100,000 (3,000) 100,000 (3,000) 100,000 (3,000)
Crankcase ventilation valves and filters 60,000 (1,800) 60,000 (1,800) 60,000 (1,800) 60,000 (1,800)
.......................................
Ignition wires and coils................ 50,000 (1,500) ................ ................ ................
Oxygen sensors.......................... 80,000 (2,400) ................ ................ ................
Air injection system components......... 110,000 (3,300) ................ ................ ................
Sensors, actuators, and related control 100,000 (3,000) 100,000 (3,000) 150,000 (4,500) 150,000 (4,500)
modules that are not integrated into
other systems..........................
Particulate filtration systems (other 100,000 (3,000) 100,000 (3,000) 250,000 (7,500) 250,000 (7,500)
than filter substrates)................
Catalyst systems (other than catalyst 110,000 (3,300) 110,000 (3,300) 185,000 (5,550) 435,000 (13,050)
substrates), fuel injectors, electronic
control modules, hybrid system
components, turbochargers, and EGR
system components (including filters
and coolers)...........................
Catalyst substrates and particulate 200,000 (10,000) 270,000 (13,000) 350,000 (17,000) 650,000 (32,000)
filter substrates......................
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[[Page 4368]]
We received no adverse comments on the proposed approach to
calculate the corresponding hours values for each minimum maintenance
interval. Consistent with our current maintenance provisions and the
proposal, we are finalizing minimum hours values based on the final
mileage and a 33 miles per hour vehicle speed (e.g., 150,000 miles
would equate to 4,500 hours).\340\ Consistent with the current
maintenance intervals specified in part 86 and the proposal, we are not
including year-based minimum intervals; OEMs can use good engineering
judgment if they choose to include a scheduled maintenance interval
based on years in their owner's manuals.
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\340\ The minimum hours-based intervals for catalyst substrates
and particulate filter substrates match the useful life hours that
apply for each primary intended service class to ensure these
components are not replaced within the regulatory useful life of the
engine, consistent with existing maintenance provisions. The useful
life hours are calculated using a 22 miles per hour conversion
factor as described in Section IV.A of this preamble.
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For new technology, not used on engines before model year 2020, we
are providing a process for manufacturers to seek approval for new
scheduled maintenance, consistent with the current maintenance
provisions. We received no adverse comment on the proposal to migrate
40 CFR 86.094-25(b)(7)(ii), which specifies a process for approval of
new critical emission-related maintenance associated with new
technology, and 40 CFR 86.094-25(b)(7)(iii), which allows manufacturers
to ask for a hearing if they object to our decision.\341\ We are
finalizing a new 40 CFR 1036.125(a)(3), as proposed.
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\341\ Hearing procedures are specified in 40 CFR 1036.820 and 40
CFR part 1068, subpart G.
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iii. Source of Parts and Repairs
Consistent with CAA section 207 \342\ and our existing regulations
for heavy duty vehicles under part 1037, we proposed a new paragraph 40
CFR 1036.125(f) to clarify that manufacturers' written instructions for
proper maintenance and use, discussed further in Section IV.B.2.vi,
generally cannot limit the source of parts and service owners use for
maintenance unless the component or service is provided without charge
under the purchase agreement, with two specified exceptions.\343\ We
are moving, with revisions, the content of the proposed paragraph (f)
to 40 CFR 1036.125(h)(2). See section 6 of the Response to Comments.
Consistent with the proposal, we are finalizing that manufacturers
cannot specify a particular brand, trade, or corporate name for
components or service and cannot deny a warranty claim due to
``improper maintenance'' based on owners choosing not to use a
franchised dealer or service facility or a specific brand of part
unless the component or service is provided without charge under the
purchase agreement. Consistent with current maintenance provisions and
CAA section 207(c)(3)(B), a second exception is that manufacturers can
specify a particular service facility and brand of parts only if the
manufacturer convinces EPA during the approval process that the engine
will only work properly with the identified service or component. We
are not finalizing at this time the proposed 40 CFR 1036.125(f)
requirement regarding specific statements on the first page of written
maintenance instructions; after consideration of comments, we agree
with commenters that the final regulatory text accomplishes the intent
of our proposal without the additional proposed first sentence.
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\342\ See, e.g., CAA section 207(c)(3)(B) and (g).
\343\ This provision has been adopted in the standard-setting
parts of several other sectors (see 1037.125(f)).
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iv. Payment for Scheduled Maintenance
We proposed 40 CFR 1036.125(g) to allow manufacturers to schedule
maintenance not otherwise allowed by 40 CFR 1036.125(a)(2) if they pay
for it. The proposed paragraph (g) also included four criteria to
identify components for which we would require manufacturers to pay for
any scheduled maintenance within the regulatory useful life. The four
criteria, which are based on current provisions that apply for nonroad
compression-ignition engines, would require manufacturers to pay for
components that were not in general use on similar engines before 1980,
whose primary purpose is to reduce emissions, where the cost of the
scheduled maintenance is more than 2 percent of the price of the
engine, and where failure to perform the scheduled maintenance would
not significantly degrade engine performance.\344\ We continue to
believe that components meeting the four criteria are less likely to be
maintained without the incentive of manufacturers paying for it and we
are finalizing 40 CFR 1036.125(g) as proposed.
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\344\ See 40 CFR 1039.125(g).
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As noted in Section IV.B.2.ii, manufacturers cannot schedule
replacement of catalyst substrates or particulate filter substrates
within the regulatory useful life of the engine unless they pay for it.
As explained in the proposed rule, in addition to catalyst substrates
and particulate filter substrates, we expect that replacement of EGR
valves, EGR coolers, and RESS of certain hybrid systems also meet the
40 CFR 1036.125(g) criteria and manufacturers will only be able to
schedule replacement of these components if the manufacturer pays for
it.
In the proposal, we requested comment on restricting the
replacement of turbochargers irrespective of the four criteria of
proposed 40 CFR 1036.125(g). One commenter suggested that EPA should
follow the CARB approach that requires manufacturers to pay for
scheduled maintenance of turbochargers within the regulatory useful
life. The comment indicated the cost of repairs and ``significant
impact'' of a failed turbocharger on emissions justify requiring that
manufacturers pay for replacement. We disagree and are not finalizing a
separate requirement for turbochargers. Turbochargers are not added to
engines specifically to control emissions and we expect the performance
degredation associated with a failing turbocharger is likely to
motivate owners to fix the problem. We continue to believe the four
criteria in 40 CFR 1036.125(g) are an appropriate means of
distinguishing components for which manufacturers should pay in order
to ensure the components are maintained.
v. Maintenance Instructions
As proposed, our final 40 CFR 1036.125 preserves the requirement
that the manufacturer provide written instructions for properly
maintaining and using the engine and emission control system,
consistent with CAA section 207(c)(3)(A).\345\ The new 40 CFR
1036.125(h) describes the information that we are requiring
manufacturers to include in an owner's manual, consistent with CAA
sections 202 and 207. The new 40 CFR 1036.125(h)(1) generally migrates
the existing maintenance instruction provisions specified in 40 CFR
86.010-38(a). As described in Section IV.B.2.iii, final 40 CFR
1036.125(h)(2) includes revised content from proposed 40 CFR
1036.125(f). The final paragraph (h)(2) is also revised from the
proposed regulatory text to clarify that EPA did not intend the
proposed paragraph as a requirement for owners to maintain
[[Page 4369]]
records in order to make a warranty claim. While 40 CFR 1036.120(d)
allows manufacturers to deny warranty claims for improper maintenance
and use, owners have expressed concern that it is unclear what
recordkeeping is needed to document proper maintenance and use, and
both the proposed and final 40 CFR 1036.125(h)(2) are intended to
ensure manufacturers are communicating their expectations to owners.
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\345\ CAA section 207(c)(3)(A) states that the manufacturer
shall furnish with each new motor vehicle or motor vehicle engine
written instructions for the proper maintenance and use of the
vehicle or engine by the ultimate purchaser and that such
instructions shall correspond to regulations which the Administrator
shall promulgate.
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Consistent with the current 40 CFR 86.010-38(a)(2), our final 40
CFR 1036.125(h)(2) also requires manufacturers to describe in the
owner's manual if manufacturers expect owners to maintain any
documentation to show the engine and emission control system have been
properly maintained and, if so, to specify what documentation.
Manufacturers should be able to identify their expectations for
documenting routine maintenance and repairs related to warranty claims.
For instance, if a manufacturer requires a maintenance log as part of
their process for reviewing warranty claims and determining whether the
engine was properly maintained, we expect the owner's manual would
provide an example log with a clear statement that warranty claims
require an up-to-date maintenance record. We note that 40 CFR 1036.125
specifies minimum maintenance intervals for critical emission-related
maintenance, and limits manufacturers from invalidating warranty if
certain other types of allowable maintenance are not performed (i.e.,
recommended additional maintenance and noncritical emission-related
maintenance). Any required maintenance tasks and intervals must be
consistent with the requirements and limitations in 40 CFR 1036.125. As
explained at proposal, we may review a manufacturer's information
describing the parameters and documentation for demonstrating proper
maintenance before granting certification for an engine family.
The maintenance instructions requirements we are finalizing for the
remainder of 40 CFR 1036.125(h) are covered in the serviceability
discussion in Section IV.B.3 and inducements discussion in Section IV.C
of this preamble. As noted in Section IV.B.3, our serviceability
provisions supplement the service information provisions specified in
40 CFR 86.010-38(j).\346\
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\346\ We are not migrating the service information provisions
into 40 CFR part 1036 in this rule.
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vi. Performing Scheduled Maintenance on Test Engines
We are finalizing our proposed update to 40 CFR 1065.410(c) to
clarify that inspections performed during testing include electronic
monitoring of engine parameters. While we intended the proposed update
to include prognostic systems, the proposed text referred only to
electronic tools, and we are revising from the proposed text in the
final provision to include ``or internal engine systems'' to clarify.
Manufacturers that include prognostic systems as part of their engine
packages to identify or predict malfunctioning components may use those
systems during durability testing and would describe any maintenance
performed as a result of those systems, consistent with 40 CFR
1065.410(d), in their application for certification. We note that, to
apply these electronic monitoring systems in testing, the inspection
tool (e.g., prognostic system) must be readable without specialized
equipment so it is available to all customers or accessible at
dealerships and other service outlets consistent with CAA sections
202(m) and 206.
3. Serviceability
This Section IV.B.3 describes the provisions we are finalizing to
improve serviceability, reduce mal-maintenance, and ensure owners are
able to maintain emission control performance throughout the entire in-
use life of heavy-duty engines. See section IV.B.2 of this preamble for
a discussion of manufacturers' obligations to provide maintenance
instructions to operators. Also see the preamble of the proposed rule
for further discussion of why EPA proposed these serviceability and
maintenance information provisions.\347\ The final serviceability and
maintenance information provisions were informed by comments, and we
summarize key comments in this section.\348\ We provide complete
responses to the serviceability-related comments in section 5 of the
Response to Comments.
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\347\ See section IV.B.3. of the proposed preamble (87 FR 17517,
March 28, 2022).
\348\ While we requested comment on several potential approaches
to improve serviceability of electric vehicles in the proposal (87
FR 17517, March 28, 2022), EPA is not taking final action on any
requirements related to this request at this time; we may consider
the comments provided on improved serviceability of electric
vehicles in future rulemakings relevant to electric vehicles. See
section 5.3 of the Response to Comments document for details on
comments received.
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i. Background
Without proper maintenance, the emission controls on heavy-duty
engines may not function as intended, which can result in increased
emissions. Mal-maintenance, which includes delayed or improper repairs
and delayed or unperformed maintenance, can be intentional (e.g.,
deferring repairs due to costs) or unintentional (e.g., not being able
to diagnose the actual problem and make the proper repair).
In the NPRM, EPA discussed stakeholder concerns with the
reliability of MY 2010 and later heavy-duty engines, and significant
frustration expressed by owners concerning their experiences with
emission control systems on such engines. EPA explained that
stakeholders have communicated to EPA that, although significant
improvements have been made to emission control systems since they were
first introduced into the market, reliability and serviceability
continue to cause them concern. EPA received comments on the NPRM
further highlighting problems from fleets, owners, and operators.
Commenters noted issues with a range of emission-related components,
including: Sensors (DPF and SCR-related), DEF dosers, hoses, filters,
EGR valves, EGR coolers and EGR actuators, SCR catalysts, DOC, turbos,
wiring, decomposition tubes, cylinder heads, and DPFs. Specifically,
for example, comments included described experiences with
aftertreatment wiring harness failures, DEF nozzles plugging or over-
injecting, NOX sensor failures, defective DEF pumps and
level sensors, systems being less reliable in rain and cold weather,
more frequent required cleaning of DPFs than anticipated, and problems
related to DEF build-up. See section 5 of the Response to Comment for
further information and the detailed comments.
In addition to existing labeling, diagnostic, and service
information requirements, EPA proposed to require important maintenance
information be made available in the owner's manual as a way to improve
factors that may contribute to mal-maintenance. The proposed
serviceability provisions were expected to result in better service
experiences for independent repair technicians, specialized repair
technicians, owners who repair their own equipment, and possibly
vehicle inspection and maintenance technicians. Furthermore, the
proposed provisions were intended to improve owner experiences
operating and maintaining heavy-duty engines and provide greater
assurance of long-term in-use emission reductions by reducing the
likelihood of occurrences of tampering.
Given the importance and complexity of emission control systems and
the
[[Page 4370]]
impact to drivers for failing to maintain such systems (e.g.,
inducements), EPA believes it is critical to include additional
information about emission control systems in the owner's manual. We
proposed to require manufacturers to provide more information
concerning the emission control system in the owner's manual to include
descriptions of how the emissions systems operate, troubleshooting
information, and diagrams. EPA has imposed similar requirements in the
past, such as when EPA required vacuum hose diagrams be included on the
emission label to improve serviceability and help inspection and
maintenance facilities identify concerns with that system.\349\
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\349\ See 53 FR 7675, March 9, 1988, and 55 FR 7177, February
29. 1990 for more information.
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ii. Final Maintenance Information Requirements for Improved
Serviceability
EPA received both supportive and adverse comments from a number of
stakeholders on the serviceability proposals (see section 5 of the
Response to Comments). For example, comments from service providers and
manufacturers largely objected to the proposed serviceability
requirements, while owners and operators supported the proposed
requirements. EPA is finalizing requirements for improved
serviceability so that owners and operators can more easily understand
advanced emission control system operation and identify issues in such
systems as they arise during operation. To the extent EPA can ensure
this information is harmonized among manufacturers, we believe this
will improve the experiences of owners, operators, parts counter
specialists, and repair technicians, and reduce frustration that could
otherwise create an incentive to tamper.
CAA section 207(c)(3)(A) requires manufacturers to provide
instructions for the proper maintenance and use of a vehicle or engine
by the ultimate purchaser and requires such instructions to correspond
to EPA regulations. The final rule includes maintenance provisions
migrated and updated from 40 CFR part 86, subpart A, to a new 40 CFR
1036.125, that specify the maintenance instructions manufacturers must
provide in an owner's manual to ensure that owners can properly
maintain their vehicles (see Section IV.B.2). Additionally, as a part
of the new 40 CFR 1036.125(h), we are finalizing specific maintenance
information manufacturers must provide in the owner's manual to improve
serviceability:
EPA is finalizing with revision the proposed requirement
for manufacturers to provide a description of how the owner can use the
OBD system to troubleshoot problems and access emission-related
diagnostic information and codes stored in onboard monitoring systems.
The revision replaces the proposed requirement that the owner's manual
include general information on how to read and understand OBD codes
with a more specific set of required information. The final requirement
specifies that, at a minimum, manufacturers provide a description of
how to use the OBD system to troubleshoot and access information and
codes, including (1) identification of the OBD communication protocol
used, (2) location and type of OBD connector, (3) a brief description
of what OBD is (including type of information stored, what a
malfunction indicator light (MIL) is, explanation that some MILs may
self-extinguish), and (4) a note that certain engine and emission data
is publicly available using any scan tool, as required by EPA. As we
describe further in section IV.C.1.iii, we are not taking final action
on the proposed health monitors. Therefore, we are also not requiring
manufacturers to provide information about the role of the health
monitor to help owners service their engines before components fail in
the description of the OBD system.
EPA is finalizing as proposed, with a few clarifications
in wording, a requirement for manufacturers to identify critical
emission systems and components, describe how they work, and provide a
general description of how the emission control systems operate.
EPA is finalizing as proposed the requirement for
manufacturers to include one or more diagrams of the engine and its
emission-related components, with two exceptions: (1) We are not
finalizing the proposed requirements to include the identity, location,
and arrangement of wiring in the diagram, and we are not requiring
information related to the expected pressures at the particulate filter
and exhaust temperatures throughout the aftertreatment system. The
final requirement specifies the following information is required, as
proposed:
[cir] The flow path for intake air and exhaust gas.
[cir] The flow path of evaporative and refueling emissions for
spark-ignition engines, and DEF for compression-ignition engines, as
applicable.
[cir] The flow path of engine coolant if it is part of the emission
control system described in the application for certification.
[cir] The identity, location, and arrangement of relevant emission
sensors, DEF heater and other DEF delivery components, and other
critical emission-related components.
[cir] Terminology to identify components must be consistent with
codes the manufacturer uses for the OBD system.
EPA is revising the proposed requirement relating to
exploded-view drawings and basic assembly requirements in the owner's
manual. The final provision replaces a general reference to
aftertreatment devices with a specific list of components that should
be included in one or more diagrams in the owner's manual, including:
EGR Valve, EGR actuator, EGR cooler, all emission sensors (e.g.,
NOX, soot sensors, etc.), temperature and pressure sensors
(EGR, DPF, DOC, and SCR-related, including DEF-related temperature and
pressure sensors), fuel (DPF-related) and DEF dosing units and
components (e.g., pumps, filters, metering units, nozzles, valves,
injectors), DEF quality sensors, DPF filter, DOC, SCR catalyst,
aftertreatment-related control modules, any other DEF delivery-related
components (e.g., lines and freeze protection components), and
aftertreatment-related wiring harnesses if replaceable separately. The
revision also notes that the information could be provided in multiple
diagrams. We are also revising the proposed requirement to include part
numbers for all components in the drawings and instead are only
requiring part numbers for sensors and filters related to SCR or DPF
systems. We are not finalizing at this time the broader requirement
that this information include enough detail to allow a mechanic to
replace any of these components. Finally, once published for a given
model year, manufacturers will not be required to revise their owner's
manual with updated part numbers if a part is updated in that model
year. We recognize that manufacturers are able to use outdated part
numbers to find updated parts.
EPA is finalizing as proposed the requirement for
manufacturers to provide a statement instructing owners or service
technicians where and how to find emission recall and technical repair
information available without charge from the National Highway Traffic
Safety Administration.\350\
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\350\ NHTSA provides this information at https://www.nhtsa.gov/recalls. For example, manufacturers should specify if the
information would be listed under ``Vehicle'' or ``Equipment.''
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EPA is finalizing with some modifications from the
proposal the requirement for manufacturers to
[[Page 4371]]
include a troubleshooting guide to address SCR inducement-related and
DPF regeneration-related warning signals. For the SCR system this
requirement includes:
[cir] The inducement derate schedule (including indication that DEF
quantity-related inducements will be triggered prior to the DEF tank
being completely empty).
[cir] The meaning of any trouble lights that indicate specific
problems (e.g., DEF level).
[cir] A description of the three types of SCR-related derates (DEF
quantity, DEF quality and tampering) and a notice that further
information on the cause of (e.g., trouble codes) is available using
the OBD system.
For the DPF system the troubleshooting guide requirement
includes:
[cir] Information on the occurrence of DPF-related derates.
[cir] EPA is finalizing in 40 CFR 1036.110(c) that certain
information must be displayed on-demand for operators. Specifically,
EPA is finalizing the requirement that for SCR-related inducements,
information such as the derate and associated fault code must be
displayed on-demand for operators (see section IV.D.3 for further
information). EPA is also finalizing requirements that the number of
DPF regenerations, DEF consumption rate, and the type of derate (e.g.,
DPF- or SCR-related) and associated fault code for other types of
emission-related derates be displayed on-demand for operators (see
section IV.C.1.iii for further information).
EPA proposed that manufacturers include a Quick Response (QR) code
on the emission label that would direct repair technicians, owners, and
inspection and maintenance facilities to a website providing critical
emission systems information at no cost. We are not taking final action
at this time on the proposed requirement to include QR codes on the
emission control information label. After considering manufacturers'
comments, we intend to engage in further outreach and analysis before
adopting electronic labeling requirements, such as QR codes. In this
rule, we are instead finalizing that the owner's manual must include a
URL directing owners to a web location for the manufacturer's service
information required in 40 CFR 86.010-38(j). We recognize the potential
for electronic labels with QR codes or similar technology to provide
useful information for operators, inspectors, and others. Manufacturers
from multiple industry sectors are actively pursuing alternative
electronic labeling. In the absence of new requirements for electronic
labeling, manufacturers must continue to meet requirements for applying
physical labels to their engines. Manufacturers may include on the
vehicle or engine any QR codes or other electronic labeling information
that goes beyond what is required for the physical emission control
information label. EPA is also not taking final action at this time on
the proposed requirement to include a basic wiring diagram for
aftertreatment-related components in the owner's manual. Finally, EPA
is not taking final action at this time on requirements related to DPF
cleaning; instead, EPA intends to continue to follow the work CARB has
undertaken in this area and may consider taking action in a future
rule.
iii. Other Emission Controls Education Options
In addition to our proposed provisions to provide more easily
accessible service information for operators, we sought comment on
whether educational programs and voluntary incentives could lead to
better maintenance and real-world emission benefits. We received
comments in response to the NPRM supportive of improving such
educational opportunities to promote an understanding of how advanced
emission control technologies function and the importance of emissions
controls as they relate to the broader economy and the environment (see
section 5.4 of the Response to Comment for further details). EPA is not
finalizing any requirements related to this request for comment at this
time but will look for future opportunities to improve the availability
of information on emission control systems.
C. Onboard Diagnostics
As used here, the terms ``onboard diagnostics'' and ``OBD'' refer
to systems of electronic controllers and sensors required by regulation
to detect malfunctions of engines and emission controls. EPA's OBD
regulations for heavy-duty engines are contained in 40 CFR 86.010-18,
which were initially promulgated on February 24, 2009 (74 FR 8310).
Those requirements were harmonized with CARB's OBD program then in
place. Consistent with our authority under CAA section 202(m), EPA is
finalizing an update to our OBD regulations in 40 CFR 1036.110 to align
with existing CARB OBD requirements as appropriate, better address
newer diagnostic methods and available technologies, and to streamline
provisions.
1. Incorporation of California OBD Regulations by Reference
CARB OBD regulations for heavy-duty engines are codified in title
13, California Code of Regulations, sections 1968.2, 1968.5, 1971.1,
and 1971.5. EPA is finalizing our proposal to incorporate by reference
in 40 CFR 1036.810 the OBD requirements CARB adopted October 3,
2019.351 352 In response to the NPRM, EPA received a number
of comments supportive of EPA's adoption of the revised CARB OBD
program, including the 2019 rule amendments. As discussed in this
section and reflected in final 40 CFR 1036.110(b), our final rule will
harmonize with the majority of CARB's existing OBD regulations, as
appropriate and consistent with the CAA, and make these final
requirements mandatory beginning in MY 2027 and optional in earlier
model years. These new requirements better address newer diagnostic
methods and available technologies and have the additional benefit of
being familiar to industry. For example, the new tracking requirements
contained in CARB's updated OBD program, known as the Real Emissions
Assessment Logging (``REAL'') program, track real-world emissions
systems performance of heavy-duty engines. The REAL tracking
requirements include the collection of onboard data using existing OBD
sensors and other vehicle performance parameters, which will better
allow the assessment of real world, in-use emission performance.
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\351\ This CARB rulemaking became effective the same day and
began to phase in under CARB's regulations with MY 2022. The CARB
regulations we are adopting are available at: https://ww2.arb.ca.gov/resources/documents/heavy-duty-obd-regulations-and-rulemaking.
\352\ The legal effect of incorporation by reference is that the
material is treated as if it were published in the Federal Register
and CFR. This material, like any other properly issued rule, has the
force and effect of law. Congress authorized incorporation by
reference in the Freedom of Information Act to reduce the volume of
material published in the Federal Register and CFR. (See 5 U.S.C.
552(a) and 1 CFR part 51). See https://www.archives.gov/federal-register/cfr/ibr-locations.html for additional information.
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EPA's final OBD requirements are closely aligned with CARB's
existing requirements with a few exceptions, as further described in
Section IV.C.1.i. We are finalizing exclusions to certain provisions
that are not appropriate for a Federal program and including additional
elements to improve on the usefulness of OBD systems for operators.
[[Page 4372]]
i. CARB OBD Provisions Revised or Not Included in the Finalized Federal
Program
CARB's 2019 OBD program includes some provisions that may not be
appropriate for the Federal regulations.\353\ In a new 40 CFR
1036.110(b), we are finalizing the following clarifications and changes
to the 2019 CARB regulations that we are otherwise incorporating by
reference:
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\353\ EPA is reviewing a waiver request under CAA section 209(b)
from California for the Omnibus rule; note, we are making no
determination in this action about the appropriateness of these
provisions for CARB's regulation.
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1. Modifying the threshold requirements contained in the 2019 CARB
OBD standards we are adopting (as discussed in Section IV.C.1.ii),
2. Providing flexibilities to delay compliance up to three model
years for small manufacturers who have not previously certified an
engine in California,
3. Allowing good engineering judgment to correlate the CARB OBD
standards with EPA OBD standards,
4. Clarifying that engines must comply with OBD requirements
throughout EPA's useful life as specified in 40 CFR 1036.104, which may
differ from CARB's required useful life for some model years,
5. Clarifying that the purpose and applicability statements in 13
CCR 1971.1(a) and (b) do not apply,
6. Not requiring the manufacturer self-testing and reporting
requirements in 13 CCR 1971.1(l)(4) ``Verification of In-Use
Compliance'' and 1971.5(c) ``Manufacturer Self-Testing'' (note, in the
proposal we inadvertently cited incorrect CARB provisions for the
intended referenced requirements),
7. Retaining our existing deficiency policy (which we are also
migrating into 40 CFR 1036.110(d)), adjusting our deficiency timing
language to match CARB's, and specifying that the deficiency provisions
in 13 CCR 1971.1(k) do not apply,
8. Requiring additional freeze frame data requirements (as further
explained in Section IV.C.1.iii),
9. Requiring additional data stream parameters for compression- and
spark-ignition engines (as further explained in Section IV.C.1.iii),
and
10. Providing flexibilities to reduce redundant demonstration
testing requirements for engines certified to CARB OBD requirements.
With regard to the second through the fifth items, EPA is
finalizing these requirements as proposed for the reasons stated in the
proposal. For the sixth item, EPA is finalizing this requirement for
the reasons stated in the proposal and as proposed with the exception
of a correction to the CARB reference we cited.
EPA received supportive comment from manufacturers on our proposal
to migrate our existing deficiency requirements, and adverse comment
from manufacturers and CARB requesting that EPA harmonize with CARB's
retroactive deficiency provisions. CARB's deficiency requirements are
described in 13 CCR 1971.1(k) and include descriptions of requirements
such as how deficiencies are granted, fines charged for deficiencies,
allowable timelines, and the application of retroactive deficiencies.
We are finalizing as proposed to migrate our existing approach to
deficiency provisions in 40 CFR 86.010-18(n) into 40 CFR
1036.110(d).\354\ See section 7.1 of the Response to Comments for
further details on comments received and EPA's responses.
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\354\ See 74 FR 8310, 8349 (February 24, 2009).
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EPA also received comment concerned with EPA's regulatory language
describing the allowable timeframe for deficiencies. Commenters said
EPA's proposed deficiency timeline is shorter than CARB's and that EPA
should harmonize with CARB and provide manufacturers with 3 years to
make hardware-related changes. EPA is finalizing a change to 40 CFR
1036.110(d)(3) to ensure our language is consistent with CARB's
deficiency timeline in 13 CCR 1971.1(k)(4).
EPA received supportive and adverse comment on the proposal to
require additional freeze frame data requirements, including that the
reference in our regulations was overly broad and possibly in error.
EPA is finalizing these requirements with revisions to those proposed
in 40 CFR 1036.110(b)(8) to be more targeted. It is critical for there
to be sufficient emissions-related parameters captured in freeze frame
data to enable proper repairs.
EPA received supportive and adverse comment on the proposal to
require additional data stream parameter requirements, including
comment that our regulations needed to be more specific. EPA is
finalizing these requirements with revisions to those proposed in 40
CFR 1036.110(b)(9) to properly capture the additional elements we
intended to add to the freeze frame and to ensure these additional
parameters are interpreted properly as an expansion of the existing
data stream requirements in 13 CCR 1971.1(h)(4.2). Access to important
emissions-related data parameters is critical for prompt and proper
repairs.
EPA is finalizing flexibilities to reduce redundant demonstration
testing requirements for engines certified to CARB OBD requirements,
see section IV.C.1.iv. of this preamble for further discussion on what
we are finalizing.
It is important to emphasize that by not incorporating certain
existing CARB OBD requirements (e.g., the ``Manufacturer Self-Testing''
requirements) into our regulations, we are not waiving our authority to
require such testing on a case-by-case basis. CAA section 208 gives EPA
broad authority to require manufacturers to perform testing not
specified in the regulations in such circumstances. Thus, should we
determine in the future that such testing is needed, we would retain
the authority to require it pursuant to CAA section 208.
ii. OBD Threshold Requirements
a. Malfunction Criteria Thresholds
Existing OBD requirements specify how OBD systems must monitor
certain components and indicate a malfunction prior to when emissions
would exceed emission standards by a certain amount, known as an
emission threshold. Emission thresholds for these components under the
existing requirements in the 2019 CARB OBD update that we are
incorporating by reference are generally either an additive or
multiplicative value above the applicable exhaust emission standard.
EPA proposed to modify the threshold requirements in the 2019 CARB OBD
update to be consistent with the provisions finalized by CARB in their
Omnibus rule in December of 2021 and not tighten threshold requirements
while finalizing lower emission standards.\355\ \356\ This meant, for
example, that for monitors required to detect a malfunction before
NOX emissions exceed 1.75 times the applicable existing
NOX standard, the manufacturer would continue to use the
same numeric threshold (e.g., 0.35 g/bhp-hr NOX) for the new
emission standards finalized in this rule.
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\355\ California Air Resources Board. Staff Report: Addendum to
the Final Statement of Reasons for Rulemaking--Public Hearing to
Consider the Proposed Heavy-Duty Engine and Vehicle Omnibus
Regulation and Associated Amendments. December 20, 2021. https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2020/hdomnibuslownox/fsoraddendum.pdf.
\356\ EPA is reviewing a waiver request under CAA section 209(b)
from California for the Omnibus rule; note, we are making no
determination in this action about the appropriateness of these
provisions for CARB's regulation.
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EPA received comments from manufacturers and operators in support
[[Page 4373]]
of finalizing the threshold provisions as proposed, and a comment from
CARB stating that three engine families have recently been certified to
lower FELs indicating EPA should finalize lower thresholds. We note
that CARB stated that two of these engine families were certified with
deficiencies, and thus these engines did not fully meet all specific
OBD requirements (see section 7.1 of the Response to Comment for
further detail about these comments and EPA's responses). EPA is
finalizing with minor revision future numerical values for OBD
NOX and PM thresholds that align with the numerical value
that results under today's NOX and PM emissions
requirements.
We are finalizing as proposed a NOX threshold of 0.40 g/
hp-hr and a PM threshold of 0.03 g/hp-hr for compression-ignition
engines for operation on the FTP and SET duty cycles. We are finalizing
as proposed a PM threshold of 0.015 g/hp-hr for spark-ignition engines
for operation on the FTP and SET duty cycles. For spark-ignition
engines, we proposed NOX thresholds of 0.30 and 0.35 g/hp-hr
for monitors detecting a malfunction before NOX emissions
exceed 1.5 and 1.75 times the applicable standard, respectively. We are
finalizing these numeric threshold values without reference to what
percent exceedance is relevant and instead are clarifying that the
0.35g/hp-hr standard applies for catalyst monitors and that 0.30g/hp-hr
applies for all other monitors, to ensure the proper numeric thresholds
can be applied to engines certified under 13 CCR 1968.2 and 1971.1..
EPA intends to continue to evaluate the capability of HD OBD monitors
to accommodate lower thresholds to correspond to the lower emission
levels for the final emission standards and may consider updating
threshold requirements in the future as more in-use data becomes
available.
We also inadvertently omitted from the proposed 40 CFR 1036.110(b)
the specific threshold criteria for SI and CI engine HC and CO
emissions that coincided with our overall expressed intent to harmonize
with the threshold requirements included in CARB's Omnibus rule and not
tighten OBD emission thresholds.\357\ Consistent with this intent, we
are finalizing a provision in 40 CFR 1036.110(b)(5) that instructs
manufacturers to use numeric values that correspond to existing HC and
CO standards (0.14 g/hp-hr for HC, 15.5 g/hp-hr for CO from
compression-ignition engines, and 14.4 g/hp/hr for spark-ignition
engines) to determine the required thresholds. Applying this
methodology will result in calculations that produce thresholds
equivalent to existing thresholds. Including this clarification avoids
unintentionally lowering such thresholds.
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\357\ While CARB standards refer to nonmethane hydrocarbon
standards as ``NMHC'' EPA's regulation refers to ``HC'' generically
for such standards, but we define HC in 40 CFR 1036.104 to be NMHC
for gasoline- and diesel-fueled engines.
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b. Test-Out Criteria
CARB OBD requirements include ``test-out'' provisions in 13 CCR
1968.2 and 1971.1 which allow manufacturers to be exempt from
monitoring certain components if failure of these components meets
specified criteria.\358\ EPA is adopting these test-out provisions
through the incorporation by reference of CARB's updated 2019 OBD
requirements. Similar to the revisions we proposed and are finalizing
for malfunction criteria, EPA's assessment is that for compression
ignition engines test-out criteria should also not be tightened at this
time. However, we inadvertently omitted from the proposed 40 CFR
1036.110(b) the specific adjustments to test-out criteria for
compression-ignition engines included in CARB's Omnibus rule that are
necessary to result in such criteria not being tightened. Consistent
with our overall expressed intent to (1) not tighten OBD requirements,
and (2) modify the 2019 CARB requirements we are adopting by
harmonizing with the numeric values included in CARB's Omnibus rule, we
are finalizing a revision from the proposal to include test-out
criteria calculation instructions into our regulations.
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\358\ ``Test-out'' provisions may be identified in CARB OBD
regulations specifically as ``test-out'' requirements or through
language describing that certain components or systems are ``exempt
from monitoring'' if manufacturers can demonstrate certain
conditions are met.
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Specifically, we are finalizing a provision that manufacturers
seeking to use the test-out criteria to exempt engines from certain
monitoring in the incorporated by reference 2019 CARB regulations 13
CCR 1968.2 and 1971.1 must calculate the criteria based on specified
values provided in 40 CFR 1036.110(b)(5). For example, 13 CCR
1971.1(e)(3.2.6) specifies that one of the requirements for an EGR
catalyst to be exempt from monitoring is if no malfunction of the EGR
catalyst can cause emissions to increase by 15 percent or more of the
applicable standard as measured from the appropriate test cycle. The
requirement we are finalizing in 40 CFR 1036.110(b)(5) instructs
manufacturers to use specific values for that ``applicable standard''
to calculate the required test-out criteria. For example, for the EGR
catalyst test-out provision, this would result in a NOX
test-out criterion of 0.03 g/hp-hr (0.2 g/hp-hr 0.15).
Including this provision is consistent with the intent of our proposal
and avoids unintentionally lowering such test-out criteria that would
render such test-out criteria generally inconsistent with the other
provisions we are finalizing in 40 CFR 1036.110(b)(5), and enables
manufacturers to continue using these provisions.
c. Applicable Thresholds for Engines Certified to 40 CFR Part 1036 Used
in Heavy-Duty Vehicles Less Than 14,000 Pounds GVWR
We are finalizing as proposed that engines installed in vehicles at
or below 14,000 lbs GVWR are subject to OBD requirements under the
light-duty program in 40 CFR 86.1806-17. Commenters pointed out that
the proposed rule did not specify alternative thresholds for engines
certified to 40 CFR part 1036 on an engine dynamometer that are subject
to OBD requirements under 40 CFR 86.1806-17. Without such a provision,
manufacturers would be subject to the existing thresholds in 40 CFR
86.1806-17 that are based on standards set for light-duty chassis-
certified vehicles. Consistent with our statements in the NPRM that our
proposal intended to harmonize with the threshold requirements included
in CARB's Omnibus policy and not lower emission threshold levels in our
proposed OBD regulations, we are clarifying in 40 CFR 86.1806-17(b)(9)
that the thresholds we are finalizing in 40 CFR 1036.110(b)(5) apply
equally for engines certified under 40 CFR part 1036 that are used in
vehicles at or below 14,000 lbs GVWR.
iii. Additional OBD Provisions in the Proposed Federal Program
In the NPRM, EPA proposed to include additional requirements to
ensure that OBD can be used to properly diagnose and maintain emission
control systems to avoid increased real-world emissions. This was also
a part of our effort to update EPA's OBD program and respond to
numerous concerns raised in the ANPR about the difficulty of diagnosing
and maintaining proper functionality of advanced emission control
technologies and the important role accessible and robust diagnostics
play in this process. At this time, after consideration of comments, we
are finalizing a limited set of these proposed provisions (see section
7 of the Response to Comments documents for further detail on comments
and
[[Page 4374]]
EPA's responses). Where OBD requirements between EPA and CARB may
differ, EPA is finalizing as proposed provisions allowing us to accept
CARB OBD approval as long as a manufacturer can demonstrate that the
CARB program meets the intent of EPA OBD requirements and submits
documentation as specified in 40 CFR 1036.110(b).
In this section we describe the final additional EPA certification
requirements in 40 CFR 1036.110 for OBD systems, which, consistent with
CAA section 202(m),\359\ are intended to provide more information and
value to the operator and play an important role in ensuring expected
in-use emission reductions are achieved long-term. With respect to our
proposed provisions to require additional information from OBD systems
be made publicly available, we received supportive comments from
operators and adverse comments from manufacturers. After considering
these comments, we are revising our final provision from those
proposed, as summarized here and provide in more detail in section 7 of
the Response to Comments document. We are not taking final action at
this time on the proposed requirement to include health monitors. In
addition to driver information requirements we are adopting to increase
the availability of serviceability and inducement-related information
(see section IV.B.3 and IV.D.3 respectively of this preamble), we are
also finalizing in 40 CFR 1036.110(c) that the following information
must be made available in the cab on-demand in lieu of the proposed
health monitors:
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\359\ For example, CAA section 202(m)(5) specifies that by
regulation EPA shall require (subject to an exception where
information is entitled to protection as trade secrets)
manufacturers to provide promptly to any person engaged in the
repairing or servicing of heavy-duty engines with any and all
information needed to make use of the emission control diagnostics
system required under CAA section 202 and such other information
including instructions for making emission related diagnosis and
repairs.
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The total number of diesel particulate filter regeneration
events that have taken place since installing the current particulate
filter.
Historical and current rate of DEF consumption (e.g.,
gallons of DEF consumed per mile or gallons of DEF consumed per gallon
of diesel fuel consumed.) This information is designed such that
operators can reset it as needed to capture specific data for
comparison purposes.
For AECD conditions (outside of inducements) related to
SCR or DPF systems that derate the engine (e.g., either a speed or
torque reduction), the fault code for the detected problem, a
description of the fault code, and the current restriction.
For all other health monitor provisions proposed in 40 CFR
1036.110(c)(3), we are not taking final action on those proposed
provisions at this time.
In addition to incorporating an improved list of publicly available
data parameters by harmonizing with updated CARB OBD requirements, in
40 CFR 1036.110(b)(9) EPA is finalizing as proposed for the reasons
explained further in the proposal to add signals to the list, including
to specifically require that all parameters related to fault conditions
that trigger vehicle inducement also be made readily available using
generic scan tools. EPA expects that each of these additional
requirements will be addressed even where manufacturers relied in part
on a CARB OBD approval to satisfy Federal requirements in order to
demonstrate under 40 CFR 1036.110(b) that the engine meets the intent
of 40 CFR 1036.110. The purpose of including additional parameters is
to make it easier to identify malfunctions of critical aftertreatment
related components, especially where failure of such components would
trigger an inducement. We are revising the proposed new parameters for
HD SI engines in 40 CFR 1036.110(b)(10) after considering comments. See
section 3 of the Response to Comments.
We are also finalizing a general requirement in 40 CFR
1036.110(b)(9)(vi) to make all parameters available that are used as
the basis for the decision to put a vehicle into an SCR- or DPF-related
derate. For example, if the failure of an open-circuit check for a DEF
quality sensor leads to an engine inducement, the owner/operator would
be able to identify this fault condition using a generic scan tool. We
are finalizing a requirement that manufacturers make additional
parameters available for all engines so equipped,\360\ including:
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\360\ Memorandum to Docket EPA-HQ-OAR-2019-0055: ``Example
Additional OBD Parameters''. Neil Miller, Amy Kopin. November 21,
2022.
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For Compression Ignition engines:
[cir] Inlet DOC and Outlet DOC pressure and temperature
[cir] DPF Filter Soot Load (for all installed DPFs)
[cir] DPF Filter Ash Load (for all installed DPFs)
[cir] Engine Exhaust Gas Recirculation Differential Pressure
[cir] DEF quality-related signals
[cir] Parking Brake, Neutral Switch, Brake Switch, and Clutch Switch
Status
[cir] Aftertreatment Dosing Quantity Commanded and Actual
[cir] Wastegate Control Solenoid Output
[cir] Wastegate Position Commanded and Actual
[cir] DEF Tank Temperature
[cir] DEF Doser Control Status
[cir] DEF System Pressure
[cir] DEF Pump Commanded Percentage
[cir] DEF Coolant Control Valve Control Position Commanded and Actual
[cir] DEF Line Heater Control Outputs
[cir] Speed and output shaft torque consistent with 40 CFR 1036.115(d)
For Spark Ignition Engines:
[cir] Air/Fuel Enrichment Enable flags: Throttle based, Load based,
Catalyst protection based
[cir] Percent of time not in stoichiometric operation (including per
trip and since new)
One of the more useful features in the CARB OBD program for
diagnosing and repairing emissions components is the requirement for
``freeze frame'' data to be stored by the system. To comply with this
requirement, manufacturers must capture and store certain data
parameters (e.g., vehicle operating conditions such as the
NOX sensor output reading) within 10 seconds of the system
detecting a malfunction. The purpose of storing this data is in part to
record the likely area of malfunction. EPA is finalizing a requirement
in 40 CFR 1036.110(b)(8) to require that manufacturers capture the
following elements as freeze frame data: Those data parameters
specified in 1971.1(h)(4.2.3)(E), 1971.1(h)(4.2.3)(F), and
1971.1(h)(4.2.3)(G). We are also specifying that these additional
parameters would be added according to the specifications in 13 CCR
1971.1(h)(4.3). EPA believes this is essential information to make
available to operators for proper maintenance.
iv. Demonstration Testing Requirements
Existing requirements of 40 CFR 86.010-18(l) and 13 CCR 1971.1(l)
specify the number of test engines for which a manufacturer must submit
monitoring system demonstration emissions data. Specifically, a
manufacturer certifying one to five engine families in a given model
year must provide emissions test data for a single test engine from one
engine rating, a manufacturer certifying six to ten engine families in
a given model year must provide emissions test data for a single test
engine from two different engine ratings, and a manufacturer certifying
eleven or more engine families in a given model year must provide
emissions test data for a single test engine from three different
engine ratings.
EPA received supportive and adverse comment on a proposed
flexibility to
[[Page 4375]]
reduce redundant demonstration testing requirements for certain engines
where an OBD system designed to comply with California OBD requirements
is being used in both a CARB proposed family and a proposed EPA-only
family and the two families are also identical in all aspects material
to expected emission characteristics. EPA issued guidance last year on
this issue.\361\ We are finalizing as proposed to codify this guidance
as a provision, subject to certain information submission requirements
for EPA to evaluate if this provision's requirements have been met, for
model years 2027 and later engines in 40 CFR 1036.110(b)(11).
Manufacturers may also use the flexibility in earlier model years. More
specifically, we are finalizing the provision as proposed to count two
equivalent engines families as one for the purposes of determining OBD
demonstration testing requirements, where equivalent means they are
identical in all aspects material to emission characteristics, as such,
testing is not necessary to ensure a robust OBD program. 40 CFR
1036.110(b)(11) requires manufacturers to submit additional information
as needed to demonstrate that the engines meet the requirements of 40
CFR 1036.110 that are not covered by the California Executive order, as
well as results from any testing performed for certifying engine
families (including equivalent engine families) with the California Air
Resources Board and any additional information we request as needed to
evaluate whether the requirements of this provision are met.
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\361\ EPA Guidance Document CD-2021-04 (HD Highway), April 26,
2021, ``Information on OBD Monitoring System Demonstration for Pairs
of EPA and CARB Families Identical in All Aspects Other Than
Warranty.'' Available here: https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=52574&flag=1.
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We took comment on and are finalizing language that this
flexibility will apply for cases where equivalent engine families also
have different inducement strategies. We are aware that the auxiliary
emission control devices (AECDs) needed to implement the engine
derating associated with inducements do not affect engine calibrations
in a way that would prevent OBD systems from detecting when emissions
exceed specified levels. Rather, those AECDs simply limit the range of
engine operation that is available to the driver. Thus, testing of
different inducement strategies in these AECDs would also not be
necessary to ensure a robust OBD program and we would consider such
differences between engines to not be material to emission
characteristics relevant to these OBD testing requirements. Any
difference in impacts between the engines would be a consequence of the
driver's response to the inducement itself, which could also occur even
with the same inducement strategy, rather than a difference in the
functioning of the OBD systems in the engines. In that way, inducements
are analogous to warranty for purposes of counting engine families for
OBD testing requirements. See section 8 of the Response to Comments for
details on the comments received and EPA's responses.
v. Use of CARB OBD Approval for EPA OBD Certification
Existing EPA OBD regulations allow manufacturers seeking an EPA
certificate of conformity to comply with the Federal OBD requirements
by demonstrating to EPA how the OBD system they have designed to comply
with California OBD requirements also meets the intent behind Federal
OBD requirements, as long as the manufacturer complies with certain
certification documentation requirements. EPA has implemented these
requirements by allowing a manufacturer to submit an OBD approval
letter from CARB for the equivalent engine family where a manufacturer
can demonstrate that the CARB OBD program has met the intent of the EPA
OBD program. In other words, EPA has interpreted these requirements to
allow OBD approval from CARB to be submitted to EPA for approval. We
are finalizing as proposed to migrate the language from 40 CFR 86.010-
18(a)(5) to 40 CFR 1036.110(b) to allow manufacturers to continue to
use a CARB OBD approval letter to demonstrate compliance with Federal
OBD regulations for an equivalent engine family where manufacturers can
demonstrate that the CARB OBD program has met the intent of the EPA OBD
program.
To demonstrate that your engine meets the intent of EPA OBD
requirements, we are finalizing as proposed that the OBD system must
address all the provisions described in 40 CFR 1036.110(b) and (c) and
adding clarification in 40 CFR 1036.110(b) that manufacturers must
submit information demonstrating that all EPA requirements are met. In
the case where a manufacturer chooses not to include information
showing compliance with additional EPA OBD requirements in their CARB
certification package (e.g., not including the additional EPA data
parameters in their CARB certification documentation), EPA expects
manufacturers to provide separate documentation along with the CARB OBD
approval letter to show they have met all EPA OBD requirements. This
process also applies in potential future cases where CARB has further
modified their OBD requirements such that they are different from but
meet the intent of existing EPA OBD requirements. EPA expects
manufacturers to submit documentation as is currently required by 40
CFR 86.010-18(m)(3), detailing how the system meets the intent of EPA
OBD requirements and information on any system deficiencies. As a part
of this update to EPA OBD regulations, we are clarifying as proposed in
40 CFR 1036.110(b)(11)(iii) that we can request that manufacturers send
us information needed for us to evaluate how they meet the intent of
our OBD program using this pathway. This would often mean sending EPA a
copy of documents submitted to CARB during the certification process.
vi. Use of the SAE J1979-2 Communications Protocol
In a February 2020 workshop, CARB indicated their intent to propose
allowing the use of Unified Diagnostic Services (``UDS'') through the
SAE J1979-2 communications protocol for heavy-duty OBD with an optional
implementation as early as MY 2023.\362 363\ The CARB OBD update that
includes this UDS proposal has not yet been finalized, but was
submitted to California's Office of Administrative Law for approval in
July of 2022.\364\ CARB stated that engine manufacturers are concerned
about the limited number of remaining undefined 2-byte diagnostic
trouble codes (``DTC'') and the need for additional DTCs for hybrid
vehicles. SAE J1979-2 provides 3-byte DTCs, significantly increasing
the number of DTCs that can be defined. In addition, this change would
provide additional features for data access that improve the usefulness
of generic scan tools to repair vehicles.
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\362\ SAE J1979-2 was issued on April 22, 2021 and is available
here: https://www.sae.org/standards/content/j1979-2_202104/.
\363\ CARB Workshop for 2020 OBD Regulations Update, February
27, 2020. Available here: https://ww3.arb.ca.gov/msprog/obdprog/obd_feb2020wspresentation.pdf.
\364\ CARB Proposed Revisions to the On-Board Diagnostic System
Requirements and Associated Enforcement Provisions for Passenger
Cars, Light-Duty Trucks, Medium-Duty Vehicles and Engines, and
Heavy-Duty Engines, available: https://ww2.arb.ca.gov/rulemaking/2021/obd2021.
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This update has not been finalized by CARB in time for us to
include it in this final rule. In consideration of manufacturers who
want to certify their engine families in the future for
[[Page 4376]]
nationwide use, and after consideration of expected environmental
benefits associated with the use of this updated protocol, we are
finalizing as proposed a process for reviewing and approving
manufacturers' requests to comply using the alternative communications
protocol.
While EPA believes our existing requirements in 40 CFR 86.010-
18(a)(5) allow us to accept OBD systems using SAE J1979-2 that have
been approved by CARB, there may be OEMs that want to obtain an EPA-
only certificate (i.e., does not include certification to California
standards) for engines that do not have CARB OBD approval for MYs prior
to MY 2027 (i.e., prior to when the 40 CFR part 1036 OBD provisions of
this final rule become mandatory). EPA is finalizing as proposed to
allow the use of SAE J1979-2 for manufacturers seeking EPA OBD
approval. We are adopting this as an interim provision in 40 CFR
1036.150(v) to address the immediate concern for model year 2026 and
earlier engines. Once EPA's updated OBD requirements are in effect for
MY 2027, we expect to be able to allow the use of SAE J1979-2 based on
the final language in 40 CFR 1036.110(b); however, we do not specify an
end date for the provision in 40 CFR 1036.150(v) to make sure there is
a smooth transition toward using SAE J1979-2 for model years 2027 and
later. This provides manufacturers the option to upgrade their OBD
protocol to significantly increase the amount of OBD data available to
owners and repair facilities.
CAA section 202(m)(4)(C) requires that the output of the data from
the emission control diagnostic system through such connectors shall be
usable without the need for any unique decoding information or device,
and it is not expected that the use of SAE J1979-2 would conflict with
this requirement. Further, CAA section 202(m)(5) requires manufacturers
to provide promptly to any person engaged in the repairing or servicing
of motor vehicles or motor vehicle engines, and the Administrator for
use by any such persons, with any and all information needed to make
use of the emission control diagnostics system prescribed under this
subsection and such other information including instructions for making
emission related diagnosis and repairs. Manufacturers that voluntarily
use J1979-2 as early as MY 2022 under interim provision 40 CFR
1036.150(v) would need to provide access to systems using this
alternative protocol at that time and meet all the relevant
requirements in 40 CFR 86.010-18 and 1036.110. EPA did not receive
adverse comment on the availability of tools that can read the new
protocol from manufacturers or tool providers. CARB commented that
staff anticipates tool vendors will be able to fully support the SAE
J1979-2 protocol at a fair and reasonable price for the vehicle repair
industry and consumers.
2. Cost Impacts
Heavy-duty engine manufacturers currently certify their engines to
meet CARB's OBD regulations before obtaining EPA certification for a
50-state OBD approval. We anticipate most manufacturers will continue
to certify with CARB and that they will certify to CARB's 2019 updated
OBD regulations well in advance of the EPA program taking effect;
therefore, we anticipate the incorporation by reference of CARB's 2019
OBD requirements will not result in any additional costs. EPA does not
believe the additional OBD requirements described here will result in
any significant costs, as there are no requirements for: New monitors,
new data parameters, new hardware, or new testing included in this
rule. However, EPA has accounted for possible additional costs that may
result from the final expanded list of public OBD parameters in the
``Research and Development Costs'' of our cost analysis in Section V.
EPA recognizes that there could be cost savings associated with reduced
OBD testing requirements under final 40 CFR 1036.110(c)(11). For
example, cost savings could come from the provision to not count engine
families certified separately by EPA and CARB, but otherwise identical
in all aspects material to expected emission characteristics, as
different families when determining OBD demonstration testing (see
section IV.C.1.iv of this document for further discussion on this
provision). This potential reduction in demonstration testing burden
could reduce costs such as labor and test cell time. However,
manufacturers may choose not to certify engine families in this manner
which would not translate to cost savings. Therefore, given the
uncertainty in the potential for savings, we did not quantify the costs
savings associated with this final provision.
D. Inducements
Manufacturers have deployed urea-based SCR systems to meet the
existing heavy-duty engine emission standards. EPA anticipates that
manufacturers will continue to use this technology to meet the new
NOX standards finalized in this rule. SCR is very different
from other emission control technologies in that it requires operators
to maintain an adequate supply of diesel exhaust fluid (DEF), which is
generally a water-based solution with 32.5 percent urea. Operating an
SCR-equipped engine without DEF or certain components like an SCR
catalyst could cause NOX emissions to increase to levels
comparable to having no NOX controls at all.
The proposed rule described two key aspects of how our regulations
currently require manufacturers to ensure engines will operate with an
adequate supply of high-quality DEF, which we proposed to update and
further codify. First, manufacturers currently must demonstrate
compliance with our critical emissions-related schedule maintenance
requirements, including 40 CFR 86.004-25(b). EPA has approved DEF
refills as part of manufacturers' scheduled maintenance. EPA's approval
is conditioned on manufacturers demonstrating that operators are
reasonably likely to perform such maintenance. Manufacturers have
consistently made this demonstration by designing their engines to go
into a disabled mode that decreases a vehicle's maximum speed if the
engine detects that operators are failing to provide an adequate supply
of DEF. More specifically, manufacturers have generally complied by
programming engines to restrict peak vehicle speeds after detecting
that such maintenance has not been performed or detecting that
tampering with the SCR system may have occurred. We refer to this
strategy of derating engine power and vehicle speed as an
``inducement.''
Second, EPA's current regulations in 40 CFR 86.094-22(e) require
that manufacturers comply with emission standards over the full
adjustable range of ``adjustable parameters,'' and that, in determining
the parameters subject to adjustment, EPA considers the likelihood that
settings other than the manufacturer's recommended setting will occur
in-use, including the effect of settings other than the manufacturer's
recommended settings on engine performance. We have historically
considered DEF level and quality as parameters that can be physically
adjusted and may significantly affect emissions. EPA generally has
approved manufacturers strategies consistent with guidance that
described recommendations on ways manufacturers could meet adjustable
parameter requirements when using SCR systems.\365\ This guidance
states that manufacturers should demonstrate that operators are being
made aware that DEF needs to be replaced through warnings and vehicle
performance
[[Page 4377]]
deterioration that should not create undue safety concerns but be
onerous enough to discourage drivers from operating without DEF (i.e.,
through inducement). See the proposed rule preamble for further
background and discussion of the basis of EPA's proposed inducement
regulations.
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\365\ See CISD-09-04 REVISED.
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With some modification from the proposal, EPA is adopting final
inducement regulations in this final rule. The regulatory provisions
also include changes compared to existing inducement guidance after
consideration of manufacturer designs and operator experiences with SCR
over the last several years. The inducement requirements included in
this final rule supersede the existing guidance and are mandatory
beginning in MY 2027 and voluntary prior to that and are intended to-
Ensure that all critical emission-related scheduled
maintenance has a reasonable likelihood of being performed while also
deterring tampering of the SCR system.
Set an appropriate inducement speed derating schedule that
reflects experience gained over the past decade with SCR systems.
Recognize the diversity of the real-world fleet with
derate schedules that are tailored to a vehicle's operating
characteristics.
Improve the type and amount of information operators
receive from the vehicle to both understand inducement actions and to
help avoid or quickly remedy a problem that is causing an inducement.
Allow operators to perform an inducement reset by using a
generic scan tool or allowing for the engine to self-heal during normal
driving.
Address operator frustration with false inducements and
low inducement speed restrictions that occur quickly, in part due to
concern that such frustration may potentially lead to in-use tampering
of the SCR system.
This final rule includes several changes from the proposed rule
after consideration of numerous comments. See section 8 of the Response
to Comments for the detailed comments and EPA's response to those
comments, including further discussion of the changes in the final rule
compared to the proposed rule. As an overview, EPA is adopting as a
maintenance requirement, as proposed, in 40 CFR 1036.125(a)(1) that
manufacturers must meet the specifications in new 40 CFR 1036.111,
which contains requirements for inducements related to SCR, to
demonstrate that timely replenishment with high-quality DEF is
reasonably likely to occur on in-use engines and that adjustable
parameter requirements will be met. Specifically, EPA is finalizing as
proposed to specify in 40 CFR 1036.115(f) that DEF supply and DEF
quality are adjustable parameters. Regarding DEF supply, we are
finalizing as proposed that the physically adjustable range includes
any amount of DEF that the engine's diagnostic system does not
recognize as a fault condition under new 40 CFR 1036.111. We are
adopting a requirement under new 40 CFR 1036.115(i) for manufacturers
to size DEF tanks corresponding to refueling events, which is
consistent with the regulation we are replacing under 40 CFR 86.004-
25(b)(4)(v). Under the final requirements, manufacturers can no longer
use the alternative option in 40 CFR 86.004-25(b)(6)(ii)(F) to
demonstrate high-quality DEF replenishment is reasonably likely to be
performed in use. As described in the proposed rule, EPA plans to
continue to rely on the existing guidance in CD-13-13 that describes
how manufacturers of heavy-duty highway engines determine the
practically adjustable range for DEF quality. We inadvertently proposed
to require that manufacturers use the physically adjustable range for
DEF quality as the basis for defining a fault condition for inducements
under 40 CFR 1036.111. Since we intended for the existing guidance to
addresses issues related to the physically adjustable range for DEF
quality, we are not finalizing the proposed provision in 40 CFR
1036.115(f)(2) for DEF quality. EPA intends further consider the
relationship between inducements and the practically adjustable range
for DEF quality and may consider updating this guidance in the future.
EPA is adopting requirements that inducements be triggered for
three types of fault conditions: (1) DEF supply is low, (2) DEF quality
does not meet manufacturer specifications, or (3) tampering with the
SCR system. EPA is not taking final action at this time on the proposed
requirement for manufacturers to include a NOX override to
prevent false inducements. After consideration of public comments, the
final inducement provisions at 40 CFR 1036.111 include updates from the
proposed inducement schedules; more specifically, EPA is adopting
separate inducement schedules for low-, medium-, and high-speed
vehicles. EPA is also finalizing requirements for manufacturers to
improve information provided to operators regarding inducements. The
final rule also includes a requirement for manufacturers to design
their engines to remove inducements after proper repairs are made,
through self-healing or with the use of a generic scan tool to ensure
that operators have performed the proper maintenance.
These requirements apply starting in MY 2027, though manufacturers
may optionally comply with these 40 CFR part 1036 requirements in lieu
of provisions that apply under 40 CFR part 86 early. The following
sections describe the inducement requirements for the final rule in
greater detail.
1. Inducement Triggers
Three types of fault conditions trigger inducements under 40 CFR
1036.111. The first triggering condition is DEF quantity. Specifically,
we require that SCR-equipped engines trigger an inducement when the
amount of DEF in the tank has been reduced to a level corresponding to
three remaining hours of engine operation. This triggering condition
ensures that operators will be compelled to perform the necessary
maintenance before the DEF supply runs out, which would cause emissions
to increase significantly.
The second triggering condition is DEF quality failing to meet
manufacturer concentration specifications. This triggering condition
ensures high quality DEF is used.
Third, EPA is requiring inducements to ensure that SCR systems are
designed to be tamper-resistant. We are requiring that manufacturers
design their engines to monitor for and trigger an inducement for open-
circuit fault conditions for the following components: (1) DEF tank
level sensor, (2) DEF pump, (3) DEF quality sensor, (4) SCR wiring
harness, (5) NOX sensors, (6) DEF dosing valve, (7) DEF tank
heater, (8) DEF tank temperature sensor, and (9) aftertreatment control
module (ACM). EPA is also requiring that manufacturers monitor for and
trigger an inducement if the OBD system has any signal indicating that
a catalyst is missing (see OBD requirements for this monitor in 13 CCR
1971.1(i)(3.1.6)). This list is the same as the list from the proposed
rule, with two exceptions after consideration of comments. First, we
are adding the DEF tank temperature sensor in the final rule. This
additional sensor is on par with the DEF tank heater for ensuring that
SCR systems are capable of monitoring for freezing conditions. Second,
in consideration of comment, we are removing blocked DEF lines or
dosing valves as a triggering condition because such a condition could
be caused by crystallized DEF rather than any operator action and thus
is not directly related to protecting against tampering with the SCR-
system. We believe this standardized list of required
[[Page 4378]]
tampering inducement triggers will be important for owners, operators,
and fleets in repairing their vehicles by avoiding excessive cost and
time to determine the reason for inducement.
2. Derate Schedule
We are finalizing a different set of schedules than we proposed.
First, we are adding a new category for medium-speed vehicles. Second,
we are adjusting the low-speed category to have a lower final speed
compared to the proposal and a lower average operating speed to
identify this category. Third, we increased the average operating speed
that qualifies a vehicle to be in the high-speed category. We are
adopting derate schedules for low-, medium- and high-speed vehicles as
shown in Table IV-13. Similar to the proposal, we differentiate these
three vehicle categories based on a vehicle's calculated average speed
for the preceding 30 hours of non-idle operation. Low-speed vehicles
are those with an average operating speed below 15 mph. Medium-speed
vehicles are those with average operating speeds at or above 15 and
below 25 mph. High-speed vehicles are those with average operating
speeds at or above 25 mph. Excluding idle from the calculation of
vehicle speed allows us to more effectively evaluate each vehicle's
speed profile; in contrast, time spent at idle would not help to give
an indication of a vehicle's operating characteristics for purposes of
selecting the appropriate derate schedule. EPA chose these final speeds
after consideration of stakeholder comments (see section 8.3 of the
Response to Comments for further information on comments received) and
an updated analysis of real-world vehicle speed activity data from the
FleetDNA database maintained by the National Renewable Energy
Laboratory (NREL).366 367 Our analyses provided us with
insight into the optimum way to characterize vehicles in a way to
ensure these categories received appropriate inducements that would be
neither ineffective nor overly restrictive.
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\366\ EPA's original analysis of NREL data can be found here:
Miller, Neil; Kopin, Amy. Memorandum to docket EPA-HQ-OAR-2019-0055-
0981. ``Review and analysis of vehicle speed activity data from the
FleetDNA database.'' October 1, 2021.
\367\ EPA's updated analysis of NREL data can be found here:
Miller, Neil; Kopin, Amy. Memorandum to docket EPA-HQ-OAR-2019-0055.
``Updated review and analysis of vehicle speed activity data from
the FleetDNA database.'' October 13, 2022.
Table IV-13--Inducement Schedules
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High-speed vehicles Medium-speed vehicles Low-speed vehicles
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Maximum speed (mi/ Hours of non-idle Maximum speed (mi/ Hours of non-idle Maximum speed (mi/
Hours of non-idle engine operation hr) engine operation hr) engine operation hr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
0................................................... 65 0 55 0 45
6................................................... 60 6 50 5 40
12.................................................. 55 12 45 10 35
60.................................................. 50 45 40 30 25
86.................................................. 45 70 35 .................. ..................
119................................................. 40 90 25 .................. ..................
144................................................. 35 .................. .................. .................. ..................
164................................................. 25 .................. .................. .................. ..................
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The derate schedule for each vehicle category is set up with
progressively increasing severity to induce the owner or operator to
efficiently address conditions that trigger inducements. Table IV-13
shows the derate schedules in cumulative hours. The initial inducement
applies immediately when the OBD system detects any of the triggering
fault conditions identified in section IV.D.1. The inducement schedule
then steps down over time to result in the final inducement speed
corresponding to each vehicle category. The inducement schedule
includes a gradual transition (1mph every 5 minutes) at the beginning
of each step of derate and prior to any repeat inducement occurring
after a failed repair to avoid abrupt changes, as the step down in
derate speeds in the schedules will be implemented while the vehicle is
in motion. Inducements are intended to deteriorate vehicle performance
to a point unacceptable for typical driving in a manner that is safe
but onerous enough to discourage vehicles from being operated (i.e.,
impact the ability to perform work), such that operators will be
compelled to replenish the DEF tank with high-quality DEF and not
tamper with the SCR system's ability to detect whether there is
adequate high-quality DEF. To this end, as explained in the proposal,
our analyses of vehicle operational data from NREL show that even
vehicles whose operation is focused on local or intracity travel depend
on frequently operating at highway speeds to complete commercial
work.\368\ Vehicles in an inducement under the schedules we are
finalizing would not be able to maintain commercial functions. Our
analysis of the NREL data also show that even medium- and low-speed
vehicles travel at speeds up to 70 mph and indicate that it is likely
regular highway travel is critical for low-speed vehicles to complete
their work; for example, refuse trucks need to drop off collected waste
at a landfill or transfer station before returning to neighborhoods.
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\368\ EPA's updated analysis of NREL data can be found here:
Miller, Neil; Kopin, Amy. Memorandum to docket EPA-HQ-OAR-2019-0055.
``Updated review and analysis of vehicle speed activity data from
the FleetDNA database.'' October 13, 2022.
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Motorcoach operators submitted comments describing a greater
sensitivity to any speed derate because of a much greater
responsibility for carrying people safely to their intended
destinations over longer distances, including their role in emergency
response and national defense operations. After consideration of these
comments, we are allowing manufacturers to design and produce engines
that will be installed in motorcoaches with an alternative derate
schedule that starts with a 65 mi/hr derate when a fault condition is
first detected, steps down to 50 mi/hr after 80 hours, and concludes
with a final derate speed of 25 mi/hr after 180 hours of non-idle
operation. EPA is defining motorcoaches in 40 CFR 1036.801 to include
buses that are designed to travel long distances with row seating for
at least 30 passengers. This is intended to include charter services
available to the general public.
Comments on the proposed inducement policy ranged from
[[Page 4379]]
objecting to any speed restrictions to advocating that we adopt a 5 mph
final derate speed. Some commenters supported the proposed rule, and
some commenters asserted that decreasing final derate speeds would
provide for greater assurance that operators would perform the
necessary maintenance. There was a similar range of comments regarding
the time specified for escalating the speed restrictions, with some
commenters agreeing with the proposed schedule, and other commenters
suggesting substantially more or less time.
We made several changes from proposal after consideration of
comments, including three main changes. First, as noted in the
preceding paragraphs, the final rule includes a medium-speed vehicle
category. This allows us to adjust the qualifying criterion for high-
speed vehicles to finalize a derate schedule similar to that proposed
for vehicles that are clearly operating mostly on interstate highways
over long distances. Similarly, the added vehicle category allows us to
adjust the qualifying criterion for low-speed vehicles and adopt an
appropriately more restrictive final derate schedule for those vehicles
that are operating at lower speeds in local service.
Second, we developed unique schedules for escalating the speed
restrictions for medium-speed and low-speed vehicles; this change was
based on the expectation that vehicles with lower average speeds spend
less time operating at highway speeds characteristic of inter-city
driving and will therefore not need to travel substantial distances to
return home for scheduling repair.
Third, we added derate speeds that go beyond the first four stages
of derating that we proposed for high-speed vehicles, essentially
reducing the final inducement speeds for all vehicles to be the same as
low-speed vehicles. In other words, as shown in Table IV-13, both high-
and medium-speed vehicles eventually derate to the same speeds as low-
speed vehicles, after additional transition time after the derate
begins. For example, the final derate schedule for high-speed vehicles
goes through the proposed four derate stages for high-speed vehicles.
At the fifth derate stage the vehicle begins to be treated like a
medium-speed vehicle, starting at the third derate stage for medium-
speed vehicles and progressing through the fifth derate stage for
medium-speed vehicles. At the fifth derate stage the vehicle begins to
be treated like a low-speed vehicle, similarly starting at the third
derate stage for low-speed vehicles. A similar step-down approach
applies for medium-speed vehicles, transitioning down to the derate
stages for low-speed vehicles. This progression is intended to address
the concern that vehicle owners might reassign vehicles in their fleet
to lower-speed service, or sell vehicles to someone who would use the
vehicle for different purposes that don't depend on higher-speed
operations. Our assessment is that the NREL data show that no matter
what category vehicles are, they do not travel exclusively at or below
25 mph, indicating that vehicles derated to 25 mph cannot be operated
commercially.
For the simplest type of maintenance, DEF refills, we fully expect
that the initial stage of derated vehicle speed will be sufficient to
compel vehicle operators to meet their maintenance obligations. We
expect operators will add DEF routinely to avoid inducements; however,
inducements begin three hours prior to the DEF tank being empty to
better ensure operation with an empty DEF tank is avoided.
We expect that the derate schedules in this final rule will be
fully effective in compelling operators to perform needed maintenance.
This effectiveness will be comparable to the current approach under
existing guidance, but will reduce operating costs to operators. We
believe this measured approach will also result in lower tampering
rates involving time.
3. Driver Information
In addition to the driver information requirements we are adopting
to improve serviceability and OBD (see section IV.B.3 and IV.C.1.iii
respectively of this preamble for more details on these provisions), we
are also adopting improved driver information requirements for
inducements. Specifically, we are adopting as proposed the requirement
for manufacturers to increase the amount of information provided to the
driver about inducements, including: (1) The condition causing the
derate (i.e., DEF quality, DEF quantity or tampering), (2) the fault
code and description of the code associated with the inducement, (3)
the current derate speed restriction, (4) hours until the next derate
speed decrease, and (5) what the next derate speed will be. It is
critical that operators have clear and ready access to information
regarding inducements to reduce concerns over progressive engine
derates (which can lead to motivations to tamper) as well as to allow
operators to make timely informed decisions, especially since
inducements are used by manufacturers to demonstrate that critical
emissions-related maintenance is reasonably likely to occur in-use. We
note that we are finalizing this requirement at 40 CFR 1036.110(c), in
a different regulatory section than proposed; however, the substance of
the requirement is the same as at proposal.
EPA is requiring that all inducement-related diagnostic data
parameters be made available with generic scan tools to help operators
promptly respond when the engine detects fault condition requiring
repair or other maintenance (see section IV.C.1.iii. for further
information).
4. Clearing an Inducement Condition
Following restorative maintenance, EPA is requiring that the engine
would allow the vehicle to self-heal if it confirms that the fault
condition is resolved. The engine would then remove the inducement,
which would allow the vehicle to resume unrestricted engine operation.
EPA is also requiring that generic scan tools be able to remove an
inducement condition after a successful repair. After clearing
inducement-related fault codes, all fault codes are subject to
immediate reevaluation that would lead to resuming the derate schedule
where it was at the time the codes were cleared if the fault persists.
Therefore, there is no need to limit the number of times a scan tool
can clear codes. Use of a generic scan tool to clear inducements would
allow owners who repair vehicles outside of commercial facilities to
complete the repair without delay (e.g., flushing and refilling a DEF
tank where contaminated DEF was discovered). However, if the same fault
condition repeats within 40 hours of engine operation (e.g., in
response to a DEF quantity fault an owner adds a small but insufficient
quantity of DEF), this will be considered a repeat faut. In response to
a repeat fault, the system will immediately resume the derate at the
same point in the derate schedule when the original fault was
deactivated. This is less time than the 80 hours EPA proposed in the
NPRM, but it is consistent with existing EPA guidance. After
consideration of comments, we believe that the shorter interval is long
enough to give a reliable confirmation that a repair has properly
addressed the fault condition, and are concerned that 80 hours would
risk treating an unrelated occurrence of a fault condition as if it
were a continuation of the same fault.
EPA is not finalizing the proposed provision that an inducement
schedule is applied and tracked independently for each fault if
multiple fault conditions are detected due to the software complexity
for the
[[Page 4380]]
manufacturer in applying and tracking the occurrence of multiple derate
schedules. Section 4 of the Response to Comments for further discussion
of EPA's thinking to assist manufacturers regarding consideration for
programming diagnostic systems to handle overlapping fault conditions.
5. Further Considerations
EPA is not taking final action at this time on the proposed
NOX override provision, which was proposed to prevent speed
derates for fault conditions that are caused by component failures if
the catalyst is nevertheless functioning normally. We received comments
describing concerns with our proposed methodology, including the
reliability of NOX sensors and use of OBD REAL
NOX data, and concerns that reliance in this way on the
NOX sensor could result in easier tampering. We are
continuing to consider these issues and comments. We may consider such
a provision in an appropriate future action. Our final inducement
regulations will reduce the risk of false inducements and provide
increased certainty during repairs by limiting inducements to well-
defined fault conditions that focus appropriately on DEF supply, DEF
quality, and tampering (open-circuit faults associated with missing
aftertreatment hardware).
We have also learned from the last several years that it is
important to monitor in-use experiences to evaluate whether the
inducement provisions are striking the intended balance of ensuring an
adequate supply of high-quality DEF in a way that is allowing for safe
and timely resolution, even for cases involving difficult
circumstances. For example, we might hypothetically learn from in-use
experiences that component malfunctions, part shortages, or other
circumstances are leaving operators in a place where inducements
prevent them from operating and they are unable to perform maintenance
that is needed to resolve the fault condition. Conversely, we might
hypothetically learn that operators are routinely driving vehicles with
active derates. Information from those in-use experiences may be
helpful for future assessments of whether we should pursue adjustments
to the derate schedules or other inducement provisions we are adopting
in this final rule.
6. In-Use Retrofits To Update Existing Inducement Algorithms
In the NPRM, we sought comment on whether it would be appropriate
to allow engine manufacturers to modify earlier model year engines to
align with the new regulatory specifications. We did not propose
changes to existing regulations to address this concern. Specifically,
we sought comment on whether and how manufacturers might use field-fix
practices under EPA's field fix guidance to modify in-use engines with
algorithms that incorporate some or all the inducement provisions in
the final rule. We received numerous comments on the need to modify
existing inducement speeds and schedules from operator groups and at
least one manufacturer.\369\ We received comment on the use of field-
fixes for this purpose from CARB, stating that CARB staff does not
support the SCR inducement strategy proposed by EPA and does not
support allowing field fixes for in-use vehicles or to amend the
certification application of current model year engines for the NPRM
inducement strategy. CARB staff also commented that they would support
allowing field fixes for in-use vehicles or amending current
certification applications only if EPA adopts an inducement strategy
identical or similar to the one CARB proposed in their comments on the
proposed rule.\370\ For example, CARB suggested an inducement strategy
with a 5 mph inducement after 10 hours, following an engine restart.
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\369\ See, for example, comments from the National Association
of Small Trucking Companies, EPA-HQ-OAR-2019-0055-1130.
\370\ See comments from California Air Resources Board, EPA-HQ-
OAR-2019-0055-1186.
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EPA believes field fixes with updated inducement algorithms may
fall within EPA's field fix guidance for engines that have EPA-only
certification (i.e., does not include certification to California
standards), but has concerns about such field fixes falling within the
scope of the guidance for engines also certified by CARB if CARB
considers such changes to be tampering with respect to requirements
that apply in California. EPA intends to also consider alternative
field fix inducement approaches that manufacturers choose to develop
and propose to CARB and EPA, for engines certified by both EPA and
CARB, such as approaches that provide a more balanced inducement
strategy than that used in current certifications while still being
effective.
E. Fuel Quality
EPA has long recognized the importance of fuel quality on motor
vehicle emissions and has regulated fuel quality to enable compliance
with emission standards. In 1993, EPA limited diesel sulfur content to
a maximum of 500 ppm and put into place a minimum cetane index of 40.
Starting in 2006 with the establishment of more stringent heavy-duty
highway PM, NOX and hydrocarbon emission standards, EPA
phased-in a 15-ppm maximum diesel fuel sulfur standard to enable heavy-
duty diesel engine compliance with the more stringent emission
standards.\371\
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\371\ 66 FR 5002 January 18, 2001.
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EPA continues to recognize the importance of fuel quality on heavy-
duty vehicle emissions and is not currently aware of any additional
diesel fuel quality requirements necessary for controlling criteria
pollutant emissions from these vehicles.
1. Biodiesel Fuel Quality
As discussed in Chapter 2.3.2 of the RIA, metals (e.g., Na, K, Ca,
Mg) can enter the biodiesel production stream and can adversely affect
emission control system performance if not sufficiently removed during
production. Our review of data collected by NREL, EPA, and CARB
indicates that biodiesel is compliant with the ASTM D6751-18 limits for
Na, K, Ca, and Mg. As we explained in the proposed rule, the available
data does not indicate that there is widespread off specification
biodiesel blend stock or biodiesel blends in the marketplace. We did
not propose and are not including at this time in this final rule
requirements for biodiesel blend metal content.
While occasionally there are biodiesel blends with elevated levels
of these metals, they are the exception. Data in the literature
indicates that Na, K, Ca, and Mg levels in these fuels are less than
100 ppb on average. Data further suggests that the low levels measured
in today's fuels are not enough to adversely affect emission control
system performance when the engine manufacturer properly sizes the
catalyst to account for low-level exposure.
Given the low levels measured in today's fuels, however, we are
aware that ASTM is currently evaluating a possible revision to the
measurement method for Na, K, Ca, and Mg in D6751-20a from EN14538 to a
method that has lower detection limits (e.g., ASTM D7111-16, or a
method based on the ICP-MS method used in the 2016 NREL study). We
anticipate that ASTM will likely specify Na, K, Ca, and Mg limits in a
future update to ASTM 7467-19 for B6 to B20 blends that is an
extrapolation of the B100 limits (see RIA Chapter 2.3.2 for additional
discussion of ASTM test methods, as well as available data on levels of
metal in biodiesel and potential impacts on emission control systems).
[[Page 4381]]
2. Compliance Issues Related to Biodiesel Fuel Quality
Given the concerns we raised in the ANPR and NPRM regarding the
possibility of catalyst poisoning from metals contained in biodiesel
blends and specifically heavy-duty vehicles fueled on biodiesel blends,
and after consideration of comments on the NPRM, EPA is finalizing a
process where we will consider the possibility that an engine was not
properly maintained under the provisions of 40 CFR part 1068, subpart
F, if an engine manufacturer demonstrates that the vehicle was
misfueled in a way that exposed the engine and its aftertreatment
components to metal contaminants and that misfueling degraded the
emission control system performance. This allows a manufacturer to
receive EPA approval to exempt test results from being considered for
potential recall. For example, a manufacturer might request EPA
approval through this process for a vehicle that was historically
fueled on biodiesel blends whose B100 blend stock did not meet the ASTM
D6751-20a limit for Na, K, Ca, and/or Mg (metals which are a byproduct
of current biodiesel production methods). This process requires the
engine manufacturer to provide proof of historic misfueling with off-
specification fuels; more specifically, to qualify for the test result
exemption(s), a manufacturer must provide documentation that compares
the degraded system to a representative compliant system of similar
miles with respect to the content and amount of the contaminant. We are
also finalizing a change from the proposal in the fuel requirements
relevant to conducting in-use testing and to recruitment of vehicles
for in-use testing. The new provision in 40 CFR 1036.415(c)(1) states
that the person conducting the in-use testing may use any commercially
available biodiesel fuel blend that meets the specifications for ASTM
D975 or ASTM D7467 that is either expressly allowed or not otherwise
indicated as an unacceptable fuel in the vehicle's owner or operator
manual or in the engine manufacturer's published fuel recommendations.
As specified in final 40 CFR 1036.410, if the engine manufacturer finds
that the engine was fueled with fuel not meeting the specifications in
40 CFR 1036.415(c)(1), they may disqualify the vehicle from in-use
testing and replace it with another one.
F. Durability Testing
In this section, we describe the final deterioration factor (DF)
provisions for heavy-duty highway engines, including migration and
updates from their current location in 40 CFR 86.004-26(c) and (d) and
86.004-28(c) and (d) to 40 CFR 1036.245 and 1036.246. EPA regulations
require that a heavy-duty engine manufacturer's application for
certification include a demonstration that the engines will meet
applicable emission standards throughout their regulatory useful life.
This is often called the durability demonstration. Manufacturers
typically complete this demonstration by following regulatory
procedures to calculate a DF. Deterioration factors are additive or
multiplicative adjustments applied to the results from manufacturer
testing to quantify the emissions deterioration over useful life.\372\
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\372\ See 40 CFR 1036.240(c) and the definition of
``deterioration factor'' in 40 CFR 1036.801, which, as proposed, are
migrated and updated from 40 CFR 86.004-26 and 86.004-28 in this
final rule.
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Currently, a DF is determined directly by aging an engine and
exhaust aftertreatment system to useful life on an engine dynamometer.
This time-consuming service accumulation process requires manufacturers
to commit to product configurations well ahead of their pre-production
certification testing to complete the durability testing so EPA can
review the test results before issuing the certificate of conformity.
Some manufacturers run multiple, staggered durability tests in parallel
in case a component failure occurs that may require a complete restart
of the aging process.\373\
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\373\ See 40 CFR 1065.415.
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As explained in the NPRM, EPA recognizes that durability testing
over a regulatory useful life is a significant undertaking, which can
involve more than a full year of continuous engine operation for Heavy
HDE to test to the equivalent of the current useful life of 435,000
miles. Manufacturers have been approved, on a case-by-case basis, to
age their systems to between 35 and 50 percent of the current full
useful life on an engine dynamometer, and then extrapolate the test
results to full useful life.\374\ This extrapolation reduces the time
to complete the aging process, but data from a test program shared with
EPA show that while engine out emissions for SCR-equipped engines were
predictable and consistent, actual tailpipe emission levels were higher
by the end of useful life when compared to emission levels extrapolated
to useful life from service accumulation of 75 or lower percent useful
life.375 376 In response to the new data indicating DFs
generated by manufacturers using service accumulation less than useful
life may not be fully representative of useful life deterioration, EPA
initially worked with manufacturers and CARB to address this concern
through guidance for MY 2020 and later engines.
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\374\ See 40 CFR 86.004-26.
\375\ U.S. EPA. ``Guidance on Deterioration Factor Validation
Methods for Heavy-Duty Diesel Highway Engines and Nonroad Diesel
Engines equipped with SCR.'' CD-2020-19 (HD Highway and Nonroad).
November 17, 2020.
\376\ Truck and Engine Manufacturers Association. ``EMA DF Test
Program.'' August 1, 2017.
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While the current DF guidance is specific to SCR-equipped engines,
in this final rule we are updating our DF provisions to apply certain
aspects of the current DF guidance to all engine families starting in
model year 2027.\377\ We also are finalizing as proposed that
manufacturers may optionally use these provisions to determine their
deterioration factors for earlier model years. As noted in the
following section, as proposed, we are continuing the option for Spark-
ignition HDE manufacturers to request approval of an accelerated aging
DF determination, as is allowed in our current regulations (see 40 CFR
86.004-26(c)(2)), and our final provision extends this option to all
primary intended service classes. We are not finalizing any changes to
the existing compliance demonstration provision in 40 CFR 1037.103(c)
for evaporative and refueling emission standards. As introduced in
Section III.E, in this rule we are also promulgating refueling emission
standards for incomplete vehicles above 14,000 lb GVWR. As proposed, we
are finalizing that incomplete vehicle manufacturers certifying to the
refueling emission standards for the first time have the option to use
engineering analyses to demonstrate durability using the same
procedures that apply for the evaporative systems on their vehicles
today.
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\377\ As noted in Section III.A, the final update to the
definition of ``engine configuration'' in 40 CFR 1036.801, as
proposed, clarifies that hybrid engines and powertrains are part of
a certified configuration and subject to all of the criteria
pollutant emission standards and other requirements; thus the DF
provisions for heavy-duty engines discussed in this subsection will
apply to configurations that include hybrid components.
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In Section IV.F.1, we are finalizing two methods for determining
DFs in a new 40 CFR 1036.245 with some modifications from those
proposed, including a new option to bench-age the aftertreatment system
to limit the burden of generating a DF over the lengthened useful life
periods in Section IV.A.3. We are also codifying two DF verification
options available to
[[Page 4382]]
manufacturers in the recent DF guidance, with some modifications from
our proposed DF verification requirements. As described in Section
IV.F.2, under the final 40 CFR 1036.245 and 40 CFR 1036.246, the final
provisions include two options for DF verification to confirm the
accuracy of the DF values submitted by manufacturers for certification,
and will be required upon request from EPA. In Section IV.F.3, we
introduce a test program to evaluate a rapid-aging protocol for diesel
catalysts, the results of which we used to develop a rapid-aging test
procedure for CI engine manufacturers to be able to use in their
durability demonstration under 40 CFR 1036.245(c)(6). We are finalizing
this procedure in 40 CFR part 1065, subpart L, as new sections 40 CFR
1065.1131 through 40 CFR 1065.1145.
At this time we are not finalizing any additional testing
requirements for manufacturers to demonstrate durability of other key
components included in a hybrid configuration (e.g., battery durability
testing). We will consider additional requirements in a future rule as
we pursue other durability-related provisions for EVs, PHEVs, etc.
As described in Section XI.A.8, we are also finalizing as proposed
that manufacturers of nonroad engines may use the procedures described
in this section to establish deterioration factors based on bench-aged
aftertreatment, along with any EPA-requested in-use verification
testing.
1. Options for Determining Deterioration Factor
Accurate methods to demonstrate emission durability are key to
ensuring certified emission levels represent real world emissions, and
the efficiency of those methods is especially important in light of the
lengthening of useful life periods in this final rule. To address these
needs, we are migrating our existing regulatory option from part 86 to
part 1036 and including a new option for heavy-duty highway engine
manufacturers to determine DFs for certification. We note that
manufacturers apply these deterioration factors to determine whether
their engines meet the duty cycle standards.
Consistent with existing regulations, final 40 CFR 1036.245 allows
manufacturers to continue the current practice of determining DFs based
on engine dynamometer-based aging of the complete engine and
aftertreatment system out to regulatory useful life. In addition, under
the new DF determination option, which includes some modifications from
that proposed and which are described in this section, manufacturers
perform dynamometer testing of an engine and aftertreatment system to a
minimum required mileage that is less than regulatory useful life.
Manufacturers then bench age the aftertreatment system to regulatory
useful life and combine the aftertreatment system with an engine that
represents the engine family. Manufacturers run the combined engine and
bench-aged aftertreatment for at least 100 hours before collecting
emission data for determination of the deterioration factor. Under this
option, the manufacturer can use the accelerated bench-aging of diesel
aftertreatment procedure described in Section IV.F.3 that is codified
in the new sections 40 CFR 1065.1131 through 40 CFR 1065.1145 or
propose an equivalent bench-aging procedure and obtain prior approval
from the Agency. For example, a manufacturer might propose a different,
established bench-aging procedure for other engines or vehicles (e.g.,
procedures that apply for light-duty vehicles under 40 CFR part 86,
subpart S).
We requested comment on whether the new bench-aged aftertreatment
option accurately evaluates the durability of the emission-related
components in a certified configuration, including the allowance for
manufacturers to define and seek approval for a less-than-useful life
mileage for the dynamometer portion of the bench-aging option. This
request for comment specifically included whether or not there is a
need to define a minimum number of engine hours of dynamometer testing
beyond what is required to stabilize the engine before bench-aging the
aftertreatment, noting that EPA's bench-aging proposal focused on
deterioration of emission control components.\378\ We requested comment
on including a more comprehensive durability demonstration of the whole
engine, such as the recent diesel test procedures from CARB's Omnibus
regulation that includes dynamometer-based service accumulation of
2,100 hours or more based on engine class and other factors.\379\ We
also requested comment on whether EPA should prescribe a standardized
aging cycle for the dynamometer portion, as was done by CARB in the
Omnibus rule with their Service Accumulation Cycles 1 and 2.\380\ We
also requested cost and time data corresponding to the current DF
procedures, and projections of cost and time for the proposed new DF
options at the proposed new useful life mileages.
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\378\ We are updating, as proposed, the definition of ``low-
hour'' in 40 CFR 1036.801 to include 300 hours of operation for
engines with NOX aftertreatment to be considered
stabilized.
\379\ California Air Resources Board, '' Appendix B-1 Proposed
30-Day Modifications to the Diesel Test Procedures'', May 5, 2021,
Available online: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2020/hdomnibuslownox/30dayappb1.pdf, page 54.
\380\ California Air Resources Board, ``Staff Report: Initial
Statement of Reasons for Proposed Rulemaking, Public Hearing to
Consider the Proposed Heavy-duty Engine and Vehicle Omnibus
Regulation and Associated Amendments,'' June 23, 2020. Available
online: https://ww3.arb.ca.gov/regact/2020/hdomnibuslownox/isor.pdf,
page III-80.
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Some commentors supported the removal of the fuel-based accelerated
DF determination method, noting that it has been shown to underestimate
emission control system deterioration. Other commentors requested that
EPA retain the option, noting that it has been historically allowed.
Fuel-based accelerated aging accelerates the service accumulation using
higher-load operation based on equivalent total fuel flow on a
dynamometer. The engine is only operated out to around 35 percent of UL
based on operating hours, however the high-load operation is intended
to result in an equivalent aging out to full UL. EPA has assessed data
from the EMA DF test program and determined that the data indicated
that the aging mechanism of accelerating the aging at higher load
differs from the actual in-use deterioration
mechanism.381 382 We are not including this option in the
final provisions for determining DF based on our assessment of the
available data and have removed the option in final 40 CFR 1036.245.
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\381\ U.S. EPA. ``Guidance on Deterioration Factor Validation
Methods for Heavy-Duty Diesel Highway Engines and Nonroad Diesel
Engines equipped with SCR.'' CD-2020-19 (HD Highway and Nonroad).
November 17, 2020.
\382\ Truck and Engine Manufacturers Association. ``EMA DF Test
Program.'' August 1, 2017.
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We also received general support of the use of accelerated aging
cycles to manage the total cost and duration of the DF test, in
addition to some commenters stating that the CARB DF determination
procedure in the CARB Omnibus regulation is superior to the accelerated
aging procedure EPA proposed in 40 CFR 1036.245(b)(2). The required
hours of engine dynamometer aging in the CARB Omnibus procedure
(roughly out to 20 percent of UL for a HHD engine) provide limited
assurance on the performance of engine components out to UL, and thus
primarily provide a short-term quality assurance durability program for
engine hardware. While the purpose of EPA's DF determination procedure
is to
[[Page 4383]]
determine emission performance degradation over the useful life of the
engine, we acknowledge that there is value in performing some engine
dynamometer aging. We are finalizing an option to use accelerated
reactor bench-aging of the emission control system that is ten times a
dynamometer or field test (1,000 hours of accelerated aging would be
equivalent to 10,000 hours of standard aging), requiring a minimum
number of testing hours on an engine dynamometer, with the allowance
for the manufacturer to add additional hours of engine dynamometer-
aging at their discretion. The minimum required hours are by primary
intended service class and follow: 300 hours for SI, 1,250 hours for
Light HDE, and 1,500 hours for Medium HDE and Heavy HDE. This option
allows the DF determination to be completed within a maximum of 180
days for a Heavy HDE. We recognize that a different approach, that uses
the same aging duty-cycle for all manufacturers, would provide more
consistency across engine manufacturers. However, no data was provided
by commentors showing that the Service Accumulation Cycles 1 and 2 in
the CARB Omnibus rule are any more effective at determining
deterioration than cycles developed by the manufacturer and submitted
to EPA for approval. EPA is also concerned regarding the amount of idle
contained in each of the CARB Omnibus rule cycles. We realize that this
idle operation was included to target the degradation mechanism that
plagued the SAPO-34 SCR formulations used by manufacturers in the
2010s, however the catalyst developers are aware of this issue now and
have developed formulations that are free from this degradation
mechanism. The two most predominant degradation mechanisms are time at
high temperature and sulfur exposure, including the effects of catalyst
desulfation, and as such EPA favors duty-cycles with more aggressive
aftertreatment temperature profiles. We understand that catalyst
manufacturers now bench test the catalyst formulations under the
conditions that led to the SAPO-34 degradation to ensure that this
degradation mechanism is not present in newly developed SCR
formulations. After taking all of the comments received into
consideration, EPA has added two specified duty-cycle options in 40 CFR
1036.245(c) for DF determination, that are identical to CARB's Service
Accumulation Cycles 1 and 2. Cycle 1 consists of a combination of FTP,
RMC, LLC and extended idle, while Cycle 2 consists of a combination of
HDTT, 55-cruise, 65-cruise, LLC, and extended idle. In the case of the
second option, the manufacturer is required to use good engineering
judgment to choose the vehicle subcategory and vehicle configuration
that yields the highest load factor using the GEM model. EPA is also
providing an option for manufacturers to use their own duty cycles for
DF determination subject to EPA approval and we expect a manufacturer
to include light-load operation if it is deemed to contribute to
degradation of the aftertreatment performance. We also note that we are
finalizing requirements to stop, cooldown, and restart the engine
during service accumulation when using the options that correspond to
CARB Service Accumulation Cycles 1 and 2 for harmonization purposes,
however we note that manufacturers may make a request to EPA to remove
this requirement on a case-by-case basis.
We are finalizing critical emission-related maintenance as
described in 40 CFR 1036.125(a)(2) and 1036.245(c) in this final rule.
Under this final rule, manufacturers may make requests to EPA for
approval for additional emission-related maintenance actions beyond
what is listed in 40 CFR 1036.125(a)(2), as described in 40 CFR
1036.125(a)(1) and as allowed during deterioration testing under 40 CFR
1036.245(c).
2. Options for Verifying Deterioration Factors
We are finalizing, with some modifications from proposal, a new 40
CFR 1036.246 where, at EPA's request, the manufacturers would be
required to verify an engine family's deterioration factor for each
duty cycle up to 85 percent of useful life. Because the manufacturer
must comply with emission standards out to useful life, we retain the
authority to verify DF. We proposed requiring upfront verification for
all engine families, but have decided to make this required only in the
event that EPA requests verification. We intend to make such a request
primarily when EPA becomes aware of information suggesting that there
is an issue with the DF generated by the manufacturer. EPA anticipates
that a DF verification request may be appropriate due to consideration
of, for example: (1) Information indicating that a substantial number
of in-use engines tested under subpart E of this part failed to meet
emission standards, (2) information from any other test program or any
other technical information indicating that engines will not meet
emission standards throughout the useful life, (3) a filed defect
report relating to the engine family, (4) a change in the technical
specifications for any critical emission-related components, and (5)
the addition of a new or modified engine configuration such that the
test data from the original emission-data engine do not clearly
continue to serve as worst-case testing for certification. We are
finalizing as proposed that manufacturers may request use of an
approved DF on future model year engines for that engine family, using
the final updates to carryover engine data provisions in 40 CFR
1036.235(d), with the final provision clarifying that we may request DF
verification for the production year of that new model year as
specified in the new 40 CFR 1036.246. As also further discussed in the
following paragraphs, we are not finalizing at this time certain DF
verification provisions that we had proposed regarding timing of when
EPA may request DF verification and certain provisions for the first
model year after a failed result. Our revisions from proposal
appropriately provide flexibility for EPA to gather information based
on DF concerns. The final provisions specify that we will discuss with
the manufacturer the selection criteria for vehicles with respect to
the target vehicle mileage(s) and production model year(s) that we want
the manufacturer to test. We are finalizing that we will not require
the manufacturer to select vehicles whose mileage or age exceeds 10
years or 85 percent of useful life.
We originally included three testing options in our proposed DF
verification provisions. We are finalizing two of these options and we
are not including the option to verify DF by measuring NOX
emissions using the vehicle's on-board NOX measurement
system at this time. For the two options we are finalizing,
manufacturers select in-use engines meeting the criteria in 40 CFR
1036.246(a), including the appropriate mileage specified by EPA
corresponding to the production year of the engine family.
Under the first verification option in 40 CFR 1036.246(b)(1),
manufacturers test at least two in-use engines over all duty cycles
with brake-specific emission standards in 40 CFR 1036.104(a) by
removing each engine from the vehicle to install it on an engine
dynamometer and measure emissions. Manufacturers determine compliance
with the emission standards after applying infrequent regeneration
adjustment factors to their measured results, just as they did when
they originally certified the engine family. We are also finalizing a
requirement under this option to allow EPA to request that
manufacturers
[[Page 4384]]
perform a new determination of infrequent regeneration adjustment
factors to apply to the emissions from the engine dynamometer-based
testing. Consistent with the proposal, the engine family passes the DF
verification if 70 percent or more of the engines tested meet the duty-
cycle emission standards in 40 CFR 1036.104(a), including any
associated compliance allowance, for each pollutant over all duty
cycles. If a manufacturer chooses to test two engines under this
option, both engines have to meet the standards. Under this option, the
aftertreatment system, including all the associated wiring, sensors,
and related hardware or software is installed on the test engine. We
are finalizing an allowance in 40 CFR 1036.246(a) for the manufacturer
to use hardware or software in testing that differs from those used for
engine family and power rating with EPA approval.
Under the second verification option in 40 CFR 1036.246(b)(2), as
proposed, manufacturers test at least five in-use engines, to account
for the increased variability of vehicle-level measurement, while
installed in the vehicle using a PEMS. Manufacturers bin and report the
emissions following the in-use testing provisions in 40 CFR part 1036,
subpart E. Compliance is determined by comparing emission results to
the off-cycle emission standards in 40 CFR 1036.104(a) with any
associated compliance allowance, mean ambient temperature adjustment,
and, accuracy margin for each pollutant for each bin after adjusting
for infrequent regeneration.\383\ As proposed, the engine family passes
the DF verification if 70 percent or more of the engines tested meet
the off-cycle standards for each pollutant for each bin. In the event
that EPA requested DF verification and a DF verification fails under
the PEMS option, consistent with the proposal the manufacturer can
reverse a fail determination for the PEMS-based testing and verify the
DF using the engine dynamometer testing option in 40 CFR
1036.246(b)(1).
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\383\ For Spark-ignition HDE, we are not finalizing off-cycle
standards; however, for the in-use DF verification options, a
manufacturer compares the engine's emission results to the duty
cycle standards applying a 1.5 multiplier for model years 2027 and
later.
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EPA is not including the third option we proposed, to verify DF
using the vehicle's on-board NOX measurement system (i.e., a
NOX sensor), in the final provisions, as we have concerns
that the technology has not matured enough to make this method viable
for DF verification at this time. We did not receive any comments that
supported the availability of technology to enable accurate on-board
NOX measurement at a level needed to show compliance with
the standard. EPA acknowledges the challenges associated with the
development of a functional onboard NOX measurement method,
including data acquisition and telematic system capabilities, and may
reconsider this option in the future if the technology evolves.
As noted in the preceding paragraphs, we are not taking final
action at this time on the proposed 40 CFR 1036.246(h) provision that
proposed a process for the first MY after a DF verification resulted in
failure. Instead, we are adopting a process for DF verification
failures similar to the existing process used for manufacturer run in-
use testing failures under 40 CFR part 1036, subpart E, such that a
failure may result in an expanded discovery process that could
eventually lead to recall under our existing provisions in 40 CFR part
1068, subpart F. EPA is making this change from proposal because this
approach provides consistency with and builds upon existing processes.
The final 40 CFR 1036.246(a) specifies how to select and prepare
engines for testing. Manufacturers may exclude selected engines from
testing if they have not been properly maintained or used and the
engine tested must be in a certified configuration, including its
original aftertreatment components. Manufacturers may test engines that
have undergone critical emission-related maintenance as allowed in 40
CFR 1065.410(d), but may not test an engine if its critical emission-
related components had any other major repair.
3. Accelerated Deterioration Factor Determination
As discussed in Section IV.F.1, we are finalizing a deterioration
factor procedure where manufacturers use engine dynamometer testing for
the required minimum number of hours given in Table 1 to Paragraph
(c)(2) of 40 CFR 1036.245 in combination with an accelerated
aftertreatment catalyst aging protocol in their demonstration of heavy-
duty diesel engine aftertreatment durability through useful life. EPA
has approved accelerated aging protocols for spark-ignition engine
manufacturers to apply in their durability demonstrations for many
years. Historically, while CI engine manufacturers have the ability to
request EPA approval of an accelerated aging procedure, CI engine
manufacturers have largely opted to seek EPA approval to use a service
accumulation fuel based accelerated test with reduce mileage and
extrapolate to determine their DF.
Other regulatory agencies have promulgated accelerated aging
protocols,384 385 and we have evaluated how these or similar
protocols apply to our heavy-duty highway engine compliance program.
EPA has validated and is finalizing an accelerated aging procedure in
40 CFR part 1065, subpart L, as new sections 40 CFR 1065.1131 through
40 CFR 1065.1145 that CI engine manufacturers can choose to use in lieu
of developing their own protocol as described in 40 CFR 1036.245. The
test program that validated the diesel aftertreatment rapid-aging
protocol (DARAP) was built on existing accelerated aging protocols
designed for light-duty gasoline vehicles (64 FR 23906, May 4, 1999)
and heavy-duty engines.\386\
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\384\ California Air Resources Board. California Evaluation
Procedure For New Aftermarket Diesel Particulate Filters Intended As
Modified Parts For 2007 Through 2009 Model Year On-Road Heavy-Duty
Diesel Engines, March 1, 2017. Available online: https://ww3.arb.ca.gov/regact/2016/aftermarket2016/amprcert.pdf.
\385\ European Commission. Amending Regulation (EU) No 583/2011,
20 September 2016. Available online: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32016R1718&from=HU.
\386\ Eakle, S and Bartley, G (2014), ``The DAAAC Protocol for
Diesel Aftertreatment System Accelerated Aging''.
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i. Diesel Aftertreatment Rapid Aging Protocol
The objective of the DARAP validation program was to artificially
recreate the three primary catalytic deterioration processes observed
in field-aged aftertreatment components: Thermal aging based on time at
high temperature, chemical aging that accounts for poisoning due to
fuel and oil contamination, and deposits. The validation program had
access to three baseline engines that were field-aged to the model year
2026 and earlier useful life of 435,000 miles. Engines and their
corresponding aftertreatment systems were aged using the current,
engine dynamometer-based durability test procedure for comparison of
the results to the accelerated aging procedure. We performed
accelerated aging of the catalyst-based aftertreatment systems using
two different methods with one utilizing a burner \387\ and the other
using an engine as the source of aftertreatment aging conditions. The
validation test plan compared emissions at the following approximate
intervals: 0 percent, 25 percent, 50 percent, 75 percent, and 100
percent of the model year 2026 and earlier useful life of 435,000
miles. At proposal, we included
[[Page 4385]]
additional details of our DARAP test program in a memo to the
docket.\388\
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\387\ A burner is a computer controlled multi-fuel reactor
designed to simulate engine aging conditions.
\388\ Memorandum to Docket EPA-HQ-OAR-2019-0055: ``Diesel
Aftertreatment Rapid Aging Program''. George Mitchell. May 5, 2021.
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The DARAP validation program has completed testing of two rapidly
aged aftertreatment systems, engine and burner, and two engines, a
single FUL aged engine and a 300-hour aged engine. Our memo to the
docket includes a summary of the validation results from this program.
The results show that both accelerated aging pathways, burner and
engine, produced rapidly aged aftertreatment system results that were
not statistically significant when compared to the 9,800-hour
dynamometer aged reference system. We are currently completing
postmortem testing to evaluate the deposition of chemical poisoning on
the surface of the substrates to see how this compares to the
dynamometer aged reference system. The complete results from our
validation program are contained in a final report in the docket.\389\
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\389\ Sharp, C. (2022). Demonstration of Low NOX
Technologies and Assessment of Low NOX Measurements in
Support of EPA's 2027 Heavy Duty Rulemaking. Southwest Research
Institute. Final Report EPA Contract 68HERC20D0014.
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ii. Diesel Aftertreatment Accelerated Aging Test Procedure
The final provisions include an option for manufacturers to use the
method from the DARAP test program for DF determination and streamline
approval under 40 CFR 1036.245(c). This accelerated aging method we are
finalizing in 40 CFR part 1065, subpart L, as new sections 40 CFR
1065.1131 through 40 CFR 1065.1145 is a protocol for translating field
data that represents a given application (e.g., engine family) into an
accelerated aging cycle for that given application, as well as methods
for carrying out reactor or engine accelerated aging using that cycle.
While this testing can be carried out on an engine as well as reactor
bench, the engine option should not be confused with standard engine
dynamometer aging out to useful life or the historic fuel-based engine
dynamometer accelerated aging typically done out to 35 percent of
useful life approach that EPA will no longer allow under this final
rule. The engine option in this procedure uses the engine (1) as a
source of accelerated sulfur from the combusted fuel, (2) as a source
for exhaust gas, and (3) to generate heat. The catalyst poisoning
agents (oil and sulfur) as well as the temperature exposure are the
same between the two methods and the DARAP test program data
corroborates this. This protocol is intended to be representative of
field aging, includes exposure to elements of both thermal and chemical
aging, and is designed to achieve an acceleration of aging that is ten
times a dynamometer or field test (1,000 hours of accelerated aging
would be equivalent to 10,000 hours of standard aging).
The initial step in the method requires the gathering and analysis
of input field data that represent a greater than average exposure to
potential field aging factors. The field aging factors consist of
thermal, oil, and sulfur exposure. The thermal exposure is based on the
average exhaust temperature; however, if the engine family incorporates
a periodic infrequent regeneration event that involves exposure to
higher temperatures than are observed during normal (non-regeneration)
operation, then this temperature is used. Oil exposure is based on
field and laboratory measurements to determine an average rate of oil
consumption in grams per hour that reaches the exhaust. Sulfur exposure
is based on the sum of fuel- and oil-related sulfur consumption rates
for the engine family. The procedure provides details on how to gather
data from field vehicles to support the generation and analysis of the
field data.
Next, the method requires determination of key components for
aging. Most diesel aftertreatment systems contain multiple catalysts,
each with their own aging characteristics. This accelerated aging
procedure ages the system, not component-by-component. Therefore, it is
necessary to determine which catalyst components are the key components
that will be used for deriving and scaling the aging cycle. This
includes identification of the primary and secondary catalysts in the
aftertreatment system, where the primary is the catalyst that is
directly responsible for most of the NOX reduction, such as
a urea SCR catalyst in a compression-ignition aftertreatment system.
The secondary is the catalyst that is intended to either alter exhaust
characteristics or generate elevated temperature upstream of the
primary catalyst, such as a DOC placed upstream of an SCR catalyst,
with or without a DPF in between.
The next step in the process is to determine the thermal
deactivation rate constant(s) for each key component. This is used for
the thermal heat load calculation in the accelerated aging protocol.
The calculations for thermal degradation are based on the use of an
Arrhenius rate law function to model cumulative thermal degradation due
to heat exposure. The process of determining the thermal deactivation
rate constant begins with determining what catalyst characteristic will
be tracked as the basis for measuring thermal deactivation. Generally,
ammonia storage is the key aging metric for zeolite-based SCR
catalysts, NOX reduction efficiency at low temperature for
vanadium-based SCR catalysts, conversion rate of NO to NO2
for DOCs with a downstream SCR catalyst, and HC reduction efficiency
(as measured using ethylene) at 200 [deg]C for DOCs where the
aftertreatment system does not contain an SCR catalyst for
NOX reduction. Thermal degradation experiments are then
carried out over at least three different temperatures that accelerate
thermal deactivation such that measurable changes in the aging metric
can be observed at multiple time points over the course of no more than
50 hours. During these experiments it is important to void temperatures
that are too high to prevent rapid catalyst failure by a mechanism that
does not represent normal aging.
Generation of the accelerated aging cycle for a given application
involves analysis of the field data to determine a set of aging modes
that will represent that field operation. There are two methods of
cycle generation in 40 CFR 1065.1139, each of which is described
separately. Method 1 involves the direct application of field data and
is used when the recorded data includes sufficient exhaust flow and
temperature data to allow for determination of aging conditions
directly from the field data set. Method 2 is meant to be used when
insufficient flow and temperature data is available from the field
data. In Method 2, the field data is used to weight a set of modes
derived from the laboratory certification cycles for a given
application. These weighted modes are then combined with laboratory
recorded flow and temperatures on the certification cycles to derive
aging modes. There are two different cases to consider for aging cycle
generation, depending on whether or not a given aftertreatment system
incorporates the use of a periodic regeneration event. For the purposes
of cycle generation, a regeneration is any event where the operating
temperature of some part of the aftertreatment system is raised beyond
levels that are observed during normal (non-regeneration) operation.
The analysis of regeneration data is considered separately from normal
operating data.
The process of cycle generation begins with the determination of
the number of bench aging hours. The input into this calculation is the
number of real or field
[[Page 4386]]
hours that represent the useful life for the target application. The
target for the accelerated aging protocol is a 10-time acceleration of
the aging process, therefore the total number of aging hours is set at
service accumulation hours minus required engine dynamometer aging
hours divided by 10. The hours will then be among different operating
modes that will be arranged to result in repetitive temperature cycling
over that period. For systems that incorporate periodic regeneration,
the total duration will be split between regeneration and normal (non-
regeneration) operation. The analysis of the operation data develops a
reduced set of aging modes that represent normal operation using either
Method 1 or Method 2. Method 1 is a direct clustering method and
involves three steps: Clustering analysis, mode consolidation, and
cycle building.\390\ This method is used when sufficient exhaust flow
and temperature data are available directly from the field data. Method
2 is a cluster-based weighting of certification cycle modes when there
is insufficient exhaust flow and temperature data from the field at the
time the cycle is being developed. The initial candidate mode
conditions are temperature and flow rate combinations that are the
centroids from the analysis of each cluster.
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\390\ https://documentation.sas.com/doc/en/emref/14.3/
n1dm4owbc3ka5jn11yjkod7ov1va.htm#:~:text=The%20cubic%20clustering%20c
riterion%20(CCC,evaluated%20by%20Monte%20Carlo%20methods.
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The target for accelerated aging cycle operation is to run all the
regenerations that would be expected over the course of useful life and
the procedure provides a process for determining a representative
regeneration profile that will be used during aging. Heat load
calculation and cycle tuning are performed after the preliminary cycles
have been developed for both normal and regeneration operation. The
target cumulative deactivation is determined from the input field data,
and then a similar calculation is performed for the preliminary aging
cycle. If the cumulative deactivation for the preliminary cycle does
not match cumulative deactivation from the field data, then the cycle
is tuned over a series of steps described in 40 CFR 1065.1139 until the
target is matched.
The final assembly of the candidate accelerated aging cycle
involves the assembly of the target modes into a schedule of modes laid
out on a time basis that can be repeated until the target number of
aging hours has been reached. For cycles that incorporate periodic
regeneration modes, the regeneration frequency and duration, including
any regeneration extension added to reach thermal targets, will be used
to determine the length of the overall cycle. The number of these
cycles that is run is equal to the total number of regenerations over
full useful life. The duration of each cycle is total number of
accelerated aging hours divided by the total number of regenerations.
For multiple components with differing regeneration schedules, this
calculation is performed using the component with the fewest total
number of regenerations. The regeneration events for the more
frequently regenerating components should be spaced evenly throughout
each cycle to achieve the appropriate regeneration frequency and
duration.
The regeneration duration (including extension) is then subtracted
from the base cycle duration to calculate the duration of normal (non-
regeneration) operation in seconds. This time is split among the normal
(non-regeneration) modes in proportion to the overall target aging time
in each mode. These modes are then split and arranged to achieve the
maximum thermal cycling between high and low temperatures. No mode may
have a duration shorter than 900 seconds, not including transition
time. Mode transitions must be at least 60 seconds long and must be no
longer than 300 seconds. The transition period is considered complete
when you are within 5 [deg]C of the target temperature for the primary
key component. For modes longer than 1800 seconds, you may count the
transition time as time in mode. For modes shorter than 1800 seconds,
under the procedure you must not count the transition time as time in
mode. Modes are arranged in alternating order starting with the lowest
temperature mode and proceeding to the highest temperature mode,
followed by the next lowest temperature mode, and so forth.
The final cycle is expressed as a schedule of target temperature,
exhaust flow rate, and NOX. For a burner-based platform with
independent control of these parameters, this cycle can be used
directly. For an engine-based platform, it is necessary to develop a
schedule of speed and load targets that will produce the target exhaust
conditions based on the capabilities of the engine platform.
The accelerated oil consumption target is calculated at 10 times
the field average oil consumption that was determined from the field
data and/or laboratory measurements. Under the procedure, this oil
consumption rate must be achieved on average over the aging cycle, and
it must at least be performed during all non-regeneration modes. Under
the procedure, the lubricating oil chosen must meet the normal in-use
specifications and it cannot be altered. The oil is introduced by two
pathways, a bulk pathway and a volatile pathway. The bulk pathway
involves introduction of oil in a manner that represents oil passing
the piston rings, and the volatile pathway involves adding small amount
of lubricating oil to the fuel. Under the procedure, the oil introduced
by the volatile pathway must be between 10 percent and 30 percent of
the total accelerated oil consumption.
Sulfur exposure related to oil is already taken care of via
acceleration of the oil consumption itself. The target cumulative fuel
sulfur exposure is calculated using the field recorded average fuel
rate data and total field hours assuming a 10-ppm fuel sulfur level
(which was determined as the 90th percentile of available fuel survey
data).
For an engine-based accelerated aging platform where the engine is
used as the exhaust gas source, accelerated fuel sulfur is introduced
by increasing the fuel sulfur level. The cycle average fuel rate over
the final aging cycle is determined once that target modes have been
converted into an engine speed and load schedule. The target aging fuel
sulfur level that results in reaching the target cumulative fuel sulfur
exposure is determined from the field data using the aging cycle
average fuel rate and the total number of accelerated aging hours.
For a burner-based platform, accelerated fuel sulfur is introduced
directly as gaseous SO2. Under the procedure, the
SO2 must be introduced in a manner that does not impede any
burner combustion, and only in a location that represents the exhaust
conditions entering the aftertreatment system. Under the procedure, the
mass rate of sulfur that must be introduced on a cycle average basis to
reach the target cumulative fuel sulfur exposure from the field data is
determined after the final aging cycle has been generated.
The accelerated aging protocol is run on a bench aging platform
that includes features necessary to successfully achieve accelerated
aging of thermal and chemical aging factors. This aging bench can be
built around either an engine or a burner as the core heat generating
element. The requirements for both kinds of bench aging platform are
described in the following paragraphs.
The engine-based accelerated aging platform is built around the use
of a diesel engine for generation of heat and flow. The engine used
does not need to be the same engine as the application that is being
aged. Any diesel engine can be used, and the engine may be
[[Page 4387]]
modified as needed to support meeting the aging procedure requirements.
You may use the same bench aging engine for deterioration factor
determination from multiple engine families. The engine must be capable
of reaching the combination of temperature, flow, NOX, and
oil consumption targets required. Using an engine platform larger than
the target application for a given aftertreatment system can provide
more flexibility to achieve the target conditions and oil consumption
rates.
To increase the range of flexibility of the bench aging engine
platform, the test cell setup should include additional elements to
allow more independent control of exhaust temperature and flow than
would be available from the engine alone. For example, exhaust heat
exchangers and/or the use of cooled and uncooled exhaust pipe can be
useful to provide needed flexibility. When using heat exchangers under
this procedure, you must ensure that you avoid condensation in any part
of the exhaust system prior to the aftertreatment. You can also control
engine parameters and the calibration on the engine to achieve
additional flexibility needed to reach the target exhaust conditions.
Under this procedure, oil consumption must be increased from normal
levels to reach the target of 10 times oil consumption. As noted
earlier, oil must be introduced through a combination of a bulk
pathway, which represents the majority of oil consumption past the
piston rings, and a volatile pathway, which is achieved by adding small
amounts of lube oil to the fuel. The total oil exposure via the
volatile pathway must be between 10 percent and 30 percent of the total
accelerated oil consumption. Under this procedure, the remainder of the
oil consumption must be introduced via the bulk pathway. The volatile
portion of the oil consumption should be introduced and monitored
continuously via a mass flow meter or controller.
Under this procedure, the engine will need to be modified to
increase oil consumption via the bulk pathway. This increase is
generally achieved through a combination of engine modifications and
the selection of aging speed/load combinations that will result in
increased oil consumption rates. To achieve this, you may modify the
engine in a fashion that will increase oil consumption in a manner such
that the oil consumption is still generally representative of oil
passing the piston rings into the cylinder. Inversion of the top
compression rings as a method which has been used to increase oil
consumption successfully for the DAAAC aging program at SwRI. A
secondary method that has been used in combination with the primary
method involves the modification of the oil control rings in one or
more cylinders to create small notches or gaps (usually no more than
two per cylinder) in the top portion of the oil control rings that
contact the cylinder liner (care must be taken to avoid compromising
the structural integrity of the ring itself).
Under this procedure, oil consumption for the engine-based platform
must be tracked at least periodically via a drain and weigh process, to
ensure that the proper amount of oil consumption has been achieved. It
is recommended that the test stand include a constant volume oil system
with a sufficiently large oil reservoir to avoid oil ``top-offs''
between oil change intervals. Under this procedure, periodic oil
changes will be necessary on any engine platform, and it is recommended
that the engine be run for at least 72 hours following an oil change
with engine exhaust not flowing through the aftertreatment system to
stabilize oil consumption behavior before resuming aging. A secondary
method for tracking oil consumption is to use clean DPF weights to
track ash loading, and compare this mass of ash to the amount predicted
using the measured oil consumption mass and the oil ash concentration.
The mass of ash found by DPF weight should fall within a range of 55
percent to 70 percent of the of mass predicted from oil consumption
measurements.
The engine should also include a means of introducing supplemental
fuel to the exhaust to support regeneration if regeneration events are
part of the aging. This can be done either via post-injection from the
engine or using in-exhaust injection. The method and location of
supplemental fuel introduction should be representative of the approach
used on the target application, but manufacturers may adjust this
methodology as needed on the engine-based aging platform to achieve the
target regeneration temperature conditions.
The burner-based aging platform is built around a fuel-fired burner
as the primary heat generation mechanism. For the accelerated aging
application under this procedure, the burner must utilize diesel fuel
and it must produce a lean exhaust gas mixture. Under this procedure,
the burner must have the ability to control temperature, exhaust flow
rate, NOX, oxygen, and water to produce a representative
exhaust mixture that meets the accelerated aging cycle targets for the
aftertreatment system to be aged. Under this procedure, the burner must
include a means to monitor these constituents in real time, except in
the case of water where the system's water metering may be verified via
measurements made prior to the start of aging (such as with an FTIR)
and should be checked periodically by the same method. Under this
procedure, the accelerated aging cycle for burner-based aging must also
include representative mode targets for oxygen and water, because these
will not necessarily be met by the burner itself through combustion. As
a result, for this procedure the burner will need features to allow the
addition of water and the displacement of oxygen to reach
representative target levels of both. During non-regeneration modes, it
is recommended that the burner be operated in a manner to generate a
small amount of soot to facilitate proper ash distribution in the DPF
system.
The burner-based platform requires methods for oil introduction for
both the bulk pathway and the volatile pathway. For the bulk pathway,
manufacturers may implement a method that introduces lubricating oil in
a region of the burner that does not result in complete combustion of
the oil, but at the same time is hot enough to oxidize oil and oil
additives in a manner similar to what occurs when oil enters the
cylinder of an engine past the piston rings. Care must be taken to
ensure the oil is properly atomized and mixed into the post-combustion
burner gases before they have cooled to normal exhaust temperatures, to
insure proper digestion and oxidation of the oil constituents. The
volatile pathway oil is mixed into the burner fuel supply and combusted
in the burner. As noted earlier, under this procedure total oil
exposure via the volatile pathway must be between 10 percent and 30
percent of the total accelerated oil consumption. The consumption of
oil in both pathways should be monitored continuously via mass flow
meters or controllers. A secondary method of tracking oil consumption
is to use clean DPF weights to track ash loading and compare this mass
of ash to the amount predicted using the measured oil consumption mass
and the oil ash concentration. The mass of ash found by DPF weight
should fall within a range of 55 percent to 70 percent of the of mass
predicted from oil consumption measurements. This will also ensure that
injected oil mass is actually done in a representative manner so that
it reaches the aftertreatment system.
Under this procedure, the burner-based platform will also need a
method to introduce and mix gaseous SO2 to achieve the
accelerated sulfur targets. Under this procedure, the consumption
[[Page 4388]]
of SO2 must be monitored continuously via a mass flow meter
or controller. SO2 does not need to be injected during
regeneration modes.
The burner-based platform should also include a means of
introducing supplemental fuel to the exhaust to support regeneration if
regeneration events are part of the aging. We recommend that the method
and location of supplemental fuel introduction be representative of the
approach used on the target application, but manufacturers may adjust
this methodology as needed on the bench engine platform to achieve the
target regeneration temperature conditions. For example, to simulate
post-injected fuel we recommend to introduce the supplemental fuel into
the post-combustion burner gases to achieve partial oxidation that will
produce more light and partially oxidized hydrocarbons similar to post-
injection.
There are specific requirements for the implementation, running,
and validation of an accelerated aging cycle developed using the
processes described in this section. Some of these requirements are
common to both engine-based and burner-based platforms, but others are
specific to one platform type or the other.
We recommended carrying out one or more practice aging cycles to
help tune the cycle and aging platform to meet the cycle requirements.
These runs can be considered part of the de-greening of test parts, or
these can be conducted on a separate aftertreatment.
The final target cycle is used to calculate a cumulative target
deactivation for key aftertreatment components. Manufacturers must also
generate a cumulative deactivation target line describing the linear
relationship between aging hours and cumulative deactivation. The
temperature of all key components is monitored during the actual aging
test and the actual cumulative deactivation based on actual recorded
temperatures is calculated. The cumulative deactivation must be
maintained to within 3 percent of the target line over the course of
the aging run and if you are exceeding these limits, you must adjust
the aging stand parameters to ensure that you remain within these
limits. Under this procedure, you must stay within these limits for all
primary key components. It should be noted that any adjustments made
may require adjustment of the heat rejection through the system if you
are seeing different behavior than the target cycle suggests based on
the field data. If you are unable to meet this requirement for any
tracked secondary system (for example for a DOC where the SCR is the
primary component), you may instead track the aging metric directly and
show that you are within 3 percent of the target aging metric. Note
that this is more likely to occur when there is a large difference
between the thermal reactivity coefficients of different components.
Calculate a target line for oil accumulation and sulfur
accumulation showing a linear relationship between aging hours and the
cumulative oil exposure on a mass basis. Under this procedure, you must
stay within 10 percent of this target line for oil
accumulation, and within 5 percent of this target line for
sulfur accumulation. In the case of engine-based bulk oil accumulation
you will only be able to track this based on periodic drain and weigh
measurements. For all other chemical aging components, track exposure
based on the continuous data from the mass flow meters for these
chemical components. If your system includes a DPF, it is recommend
that you implement the secondary tracking of oil consumption using DPF
ash loading measurements as describe earlier.
For the engine-based platform, it will be necessary under this
procedure to develop a schedule of engine operating modes that achieve
the combined temperature, flow, and oil consumption targets. You may
deviate from target NOX levels as needed to achieve these
other targets, but we recommend that you maintain a NOX
level representative of the target application or higher on a cycle
average basis. Note that the need to operate at modes that can reach
the target oil consumption will leverage the flexibility of the engine
stand, and you may need to iterate on the accelerated oil consumption
modifications to achieve a final target configuration. You may need to
adjust the cycle or modify the oil consumption acceleration to stay
within the 10 percent target. In the even that you find
that actual fuel consumption varies from original assumptions, you may
need to adjust the doped fuel sulfur level periodically to maintain the
sulfur exposure within the 5 percent limit.
If the application uses DEF, it must be introduced to the exhaust
stream in a manner that represents the target application. You may use
hardware that is not identical to the production hardware but ensure
that hardware produces representative performance. Similarly, you may
use hardware that is not identical to production hardware for fuel
introduction into the exhaust as long you ensure that the performance
is representative.
Under this procedure, for the burner-based platform, you will be
able to directly implement the temperature, flow, NOX,
sulfur, and oil consumption targets. You will also need to implement
water and O2 targets to reach levels representative of
diesel exhaust. We recommend that you monitor and adjust oil and sulfur
dosing on a continuous basis to stay within targets. You must verify
the performance of the oil exposure system via the secondary tracking
of oil exposure via DPF ash loading and weighing measurements. This
will ensure that your oil introduction system is functioning correctly.
If you use a reductant, such as DEF, for NOX reduction, use
good engineering judgement to introduce DEF in a manner that represents
the target application. You may use hardware that is not identical to
the production hardware but ensure that the hardware produces
representative performance. Similarly, you may use hardware that is not
identical to production hardware for fuel introduction into the exhaust
as long you ensure that the performance is representative.
The implementation and carrying out of these procedures will enable
acceleration of the deterioration factor determination testing, and
generally allow the determination of the deterioration factor out to
useful life, over 90 days of testing.
G. Averaging, Banking, and Trading
EPA is finalizing an averaging, banking, and trading (ABT) program
for heavy-duty engines that provides manufacturers with flexibility in
their product planning while encouraging the early introduction of
emissions control technologies and maintaining the expected emissions
reductions from the program. Several core aspects of the ABT program we
are finalizing are consistent with the proposed ABT program, but the
final ABT program includes several updates after consideration of
public comments. In particular, EPA requested comment on and agrees
with commenters that a lower family emission limit (FEL) cap than
proposed is appropriate for the final rule. Further, after
consideration of public comments, EPA is not finalizing at this time
the proposed Early Adoption Incentives program, and in turn we are not
including emissions credit multipliers in the final program. Rather, we
are finalizing an updated version of the proposed transitional credit
program under the ABT program. As described in preamble Section IV.G.7,
the revised transitional credit program that we are finalizing provides
four pathways to generate straight NOX
[[Page 4389]]
emissions credits (i.e., no credit multipliers) that are valued based
on the extent to which the engines generating credits comply with the
requirements we are finalizing for MY 2027 and later (e.g., credits
discounted at a rate of 40 percent for engines meeting a lower numeric
standard but none of the other MY 2027 and later requirements) (see
section 12 of the Response to Comments document and preamble Section
IV.G.7 for more details). In addition, we are finalizing a production
volume allowance for MYs 2027 through 2029 that is consistent with the
proposal but different in several key aspects, including that
manufacturers will be required to use NOX emissions credits
to certify heavy heavy-duty engines compliant with MY 2010 requirements
in MYs 2027 through 2029 (see Section IV.G.9 for details). Finally, we
are not finalizing the proposed allowance for manufacturers to generate
NOX emissions credits from heavy-duty zero emissions
vehicles (ZEVs) (see Section IV.G.10).
Consistent with the proposed ABT program, the final ABT program
will maintain several aspects of the ABT program currently specified in
40 CFR 86.007-15, including:
Allowing ABT of NOX credits with no expiration
of the ABT program,
calculating NOX credits based on a single
NOX FEL for an engine family,
specifying FELs to the same number of decimal places as
the applicable standards, and
calculating credits based on the work and miles of the FTP
cycle.
In this Section we briefly describe the proposed ABT program, the
comments received on the proposed ABT program, and EPA's response to
those comments. Subsequent subsections provide additional details on
the restrictions we are finalizing for using emission credits in model
years 2027 and later, such as averaging sets (Section IV.G.2), FEL caps
(Section IV.G.4), and limited credit life (Section IV.G.4). See the
proposed rule preamble (87 FR 17550, March 28, 2022) for additional
discussion on the proposed ABT program and the history of ABT for
heavy-duty engines.
The proposed ABT program allowed averaging, banking, and trading of
NOX credits generated against applicable heavy-duty engine
NOX standards, while discontinuing a credit program for HC
and PM. We also proposed new provisions to clarify how FELs apply for
additional duty cycles. The proposed program included restrictions to
limit the production of new engines with higher emissions than the
standards; these restrictions included FEL caps, credit life for
credits generated for use in MYs 2027 and later, and the expiration of
currently banked credits. These provisions were included in proposed 40
CFR part 1036, subpart H. and 40 CFR 1036.104(c). In addition, we
proposed interim provisions in 40 CFR 1036.150(a)(1) describing how
manufacturers could generate credits in MY 2024 through 2026 to apply
in MYs 2027 and later. We requested comment on several aspects of the
proposed ABT program that we are updating in the final rule, including
the transitional credit program and level of the FEL cap, which
restrict the use of credits in MY 2027 and later.
Many commenters provided perspectives on the proposed ABT program.
The majority of commenters supported the proposed ABT program, although
several suggested adjustments for EPA to consider in the final rule. In
contrast, a number of commenters opposed the proposed ABT program and
argued that EPA should eliminate the NOX ABT program in the
final rule. Perspectives from commenters supporting and opposing the
proposed ABT program are briefly summarized in this section with
additional details in section 12 of the Response to Comments document.
Commenters supporting the ABT program stated that it provides an
important flexibility to manufacturers for product planning during a
transition to more stringent standards. They further stated that a
NOX ABT program would allow manufacturers to continue
offering a complete portfolio of products, while still providing real
NOX emissions reductions. In contrast, commenters opposing
the ABT program argued EPA should eliminate the NOX ABT
program in order to maximize NOX emissions reductions
nationwide, particularly in environmental justice communities and other
areas impacted by freight industry. These commenters stated that the
NOX standards are feasible without the use of credits, and
that eliminating the credit flexibilities of an ABT program would be
most consistent with EPA's legal obligations under the CAA.
EPA agrees with those commenters who support a well-designed ABT
program as a way to help us meet our emission reduction goals at a
faster pace while providing flexibilities to manufacturers to meet new,
more stringent emission standards. For example, averaging, banking, and
trading can result in emissions reductions by encouraging the
development and use of new and improved emission control technology,
which results in lower emissions. The introduction of new emission
control technologies can occur either in model years prior to the
introduction of new standards, or during periods when there is no
change in emissions standards but manufacturers still find it useful to
generate credits for their overall product planning. In either case,
allowing banking and trading can result in emissions reductions earlier
in time, which leads to greater public health benefits sooner than
would otherwise occur; benefits realized sooner in time are generally
worth more to society than those deferred to a later time.\391\ These
public health benefits are further ensured through the use of
restrictions on how and when credits may be used (e.g., averaging sets,
credit life), which are discussed further in this Section IV.G. For
manufacturers, averaging, banking, and trading provides additional
flexibility in their product planning by providing additional lead time
before all of their engine families must comply with all the new
requirements without the use of credits. For periods when no changes in
emission standards are involved, banking can provide manufacturers
additional flexibility, provide assurance against any unforeseen
emissions-related problems that may arise, and in general provide a
means to encourage the development and introduction of new engine
technology (see 55 FR 30585, July 26, 1990, for additional discussion
on potential benefits of an ABT program).
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\391\ Consistent with economic theory, we assume that people
generally prefer present to future consumption. We refer to this as
the time value of money, which means money received in the future is
not worth as much as an equal amount received today. This time
preference also applies to emissions reductions that result in the
health benefits that accrue from regulation. People have been
observed to prefer health gains that occur immediately to identical
health gains that occur in the future. Health benefits realized in
the near term are therefore worth more to society than those
deferred to a later time.
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While EPA also agrees with those commenters stating that the
standards in the final rule are feasible without the use of credits, as
described in Section III of this preamble, given the technology-forcing
nature of the final standards we disagree that providing an optional
compliance pathway through the final rule's ABT program is inconsistent
with requirements under CAA section 202(a)(3)(A).\392\ The final ABT
program appropriately balances flexibilities for manufacturers to
generate NOX
[[Page 4390]]
emissions credits with updated final restrictions (e.g., credit life,
averaging sets, and family emissions limit (FEL) caps) that in our
judgement both ensure that available emissions control technologies are
adopted and maintain the emissions reductions expected from the final
standards.\393\ An ABT program is also an important foundation for
targeted incentives to encourage manufacturers to adopt advanced
technology before required compliance dates, which we discuss further
in preamble Section IV.G.7 and Section 12 of the Response to Comments
document.
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\392\ See NRDC v. Thomas, 805 F. 2d 410, 425 (D.C. Cir. 1986),
which upheld emissions averaging after concluding that ``EPA's
argument that averaging will allow manufacturers more flexibility in
cost allocation while ensuring that a manufacturer's overall fleet
still meets the emissions reduction standards makes sense''.
\393\ As discussed in Section IV.G.9, we are finalizing an
allowance for manufacturers to continue to produce a small number (5
percent of production volume) of engines that meet the current
standards for a few model years (i.e., through MY 2030). See Section
IV.G.9 for details on our approach and rationale for including this
allowance in the final rule.
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One commenter opposing EPA's proposed NOX emissions ABT
program provided analyses for EPA to consider in developing the final
rule. EPA has evaluated the three approaches to generating credits in
the commenter's analysis: (1) Engines certified below today's standards
which qualify for the proposed transitional credit program, (2) engines
certified to the CARB Omnibus standards which would quality for the
proposed transitional program or on average achieve a standard below
Federal requirements, and (3) ZEVs. For the first category (the
transitional credit program), we considered several factors when
designing the final transitional credit program that are more fully
described in preamble Section IV.G.7; briefly, the transitional credit
program we are finalizing will discount the credits manufacturers
generated from engines certified to levels below today's standards
unless manufacturers can meet all of the requirements in the final MY
2027 and later standards. This includes meeting standards such as the
final low load cycle (LLC), which requires demonstration of emissions
control in additional engine operations (i.e., low load) compared to
today's test cycles. For the second category in the commenter's
analysis (engines certified to Omnibus standards), we recognize that
our proposed rule preamble may have been unclear regarding how the
existing regulations in part 86 and part 1036 apply for purposes of
participation in the Federal ABT program to engines that are certified
to state standards that are different than the Federal standards. We
proposed to migrate without substantive modification the definition of
``U.S.-directed production'' in 40 CFR 86.004-2 to 40 CFR part 1036.801
for criteria pollutant engine requirements, to match the existing
definition for GHG engine requirements, which excludes engines
certified to state emission standards that are different than the
Federal standards.\394\ The relevant existing NOX ABT credit
program requirements, and the relevant program requirements we are
finalizing as proposed, specify that compliance through ABT does not
allow credit calculations to include engines excluded from the
definition of U.S.-directed production volume.\395\ For the third
category in the commenter's analysis (ZEVs), as discussed in preamble
Section IV.G.10 and section 12 of the Response to Comments document, we
are not finalizing the proposed allowance for manufacturers to generate
NOX credits from ZEVs. For these reasons, EPA believes the
final ABT program will at a minimum maintain the emissions reductions
projected from the final rule, and in fact could result in greater
public health benefits by resulting in emissions reductions earlier in
time than they would occur without banking or trading. Further, if
manufacturers generate NOX emissions credits that they do
not subsequently use (e.g., due to transitioning product lines to
ZEVs), then the early emissions reductions from generating these
credits will result in more emission reductions than our current
estimates reflect. In addition, the final ABT program provides an
important flexibility for manufacturers, which we expect will help to
ensure a smooth transition to the new standards and avoid delayed
emissions reductions due to slower fleet turnover than may occur
without the flexibility of the final ABT program.
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\394\ See Section XI.B.4 for additional information.
\395\ See final part 1036, subpart H. Existing 40 CFR
1036.705(c) states the following, which we are finalizing as
proposed as also applicable to NOX ABT: ``As described in
Sec. 1036.730, compliance with the requirements of this subpart is
determined at the end of the model year based on actual U.S.-
directed production volumes. Keep appropriate records to document
these production volumes. Do not include any of the following
engines to calculate emission credits: . . . (4) Any other engines
if we indicate elsewhere in this part 1036 that they are not to be
included in the calculations of this subpart.'' See also existing 40
CFR 86.007-15 (regarding U.S.-directed production engines for the
purpose of using or generating credits during a phase-in of new
standards) and 66 FR 5114, January 18, 2001.
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In the subsections that follow we briefly summarize and provide
responses to comments on several more specific topics, including: ABT
for pollutants other than NOX (IV.G.1), Applying the ABT
provisions to multiple NOX duty-cycle standards (IV.G.2),
Averaging Sets (IV.G.3), FEL caps (IV.G.4), Credit Life (IV.G.5),
Existing credits (IV.G.6), Transitional Credits (IV.G.7), the proposed
Early Adoption Incentives (IV.G.8), and a Production Volume Allowance
under ABT (IV.G.9). The final ABT program is specified in 40 CFR part
1036, subpart H.\396\ Consistent with the proposal, we are also
finalizing a new paragraph at 40 CFR 1036.104(c) to specify how the ABT
provisions will apply for MY 2027 and later heavy-duty engines subject
to the final criteria pollutant standards in 40 CFR 1036.104(a). The
Transitional Credit program in the final rule is described in the
interim provision in 40 CFR 1036.150(a)(1), which we are finalizing
with revisions from the proposal.
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\396\ As proposed, the final rule does not include substantive
revisions to the existing GHG provisions in 40 CFR 1036, subpart H;
as proposed, the final revisions clarify whether paragraphs apply
for criteria pollutant standards or GHG standards.
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1. ABT for Pollutants Other Than NOX
After consideration of public comments, EPA is choosing to finalize
as proposed an ABT program that will not allow averaging, banking, or
trading for HC (including NOX+NMHC) or PM for MY 2027 and
later engines. This includes not allowing HC and PM emissions credits
from prior model years to be used for MY 2027 and later engines. For
engines certified to MY 2027 or later standards, manufacturers must
demonstrate in their application for certification that they meet the
final PM, HC, and CO emission standards in 40 CFR 1036.104(a) without
using emission credits.
Several commenters supported EPA's proposal to discontinue ABT for
HC and PM. These commenters stated that current heavy-duty engine
technologies can easily meet the proposed HC and PM standards, and
therefore an ABT program for these pollutants is not necessary. Some
commenters urged EPA to provide ABT programs for HC and CO based on the
stringency of the standards for these pollutants, particularly for
Spark-ignition HDE. Another commenter did not indicate support or
opposition to an HC ABT flexibility in general, but stated that EPA
should not base the final HC standard on the use of HC emissions
credits since doing so could lead to competitive disruptions between SI
engine manufacturers. One commenter also urged EPA to consider ABT
programs for regulated pollutant emissions other than NOX,
including HC, PM, CO, and N2O.
As discussed in preamble Section III, EPA demonstrated that the
final standards for NOX, HC, CO, and PM area feasible for
all engine classes, and we
[[Page 4391]]
set the numeric values without assuming manufacturers would require the
use of credits to comply. We proposed to retain and revise the
NOX ABT program and we are updating from our proposal in
this final rule as described in the following sections.
For PM, manufacturers are submitting certification data to the
agency for current production engines well below the final PM standard
over the FTP duty cycle; the final standard ensures that future engines
will maintain the low level of PM emissions of the current engines.
Manufacturers are not using PM credits to certify today and we received
no new data showing manufacturers would generate or use PM credits
starting in MY 2027; therefore, we are finalizing as proposed.
We disagree with commenters indicating that credits will be needed
for Spark-ignition HDE to meet the final HC and CO standards. Our SI
engine demonstration program data show feasibility of the final
standards (see preamble Section III.D for details). Furthermore, as
described in Section IV.G.3, we are retaining the current ABT
provisions that restrict credit use to within averaging sets and we
expect SI engine manufacturers, who have few heavy-duty engine
families, will have limited ability to generate and use credits. See
preamble Section III.D for a discussion of the final numeric levels of
the Spark-ignition HDE standards and adjustments we made to the
proposed HC and CO stringencies after further consideration.
We did not propose or request comment on expanding the heavy-duty
engine ABT program to include other regulated pollutant emissions, such
as N2O, and thus are not including additional pollutants in
the final ABT program.
2. Multiple Standards and Duty Cycles for NOX ABT
Under the current and final ABT provisions, FELs serve as the
emission standards for the engine family for compliance testing
purposes.\397\ We are finalizing as proposed new provisions to ensure
the NOX emission performance over the FTP is proportionally
reflected in the range of cycles included in the final rule for heavy-
duty engines.\398\ Specifically, manufacturers will declare a FEL to
apply for the FTP standards and then they will calculate a
NOX FEL for the other applicable cycles by applying an
adjustment factor based on their declared FELFTP. As
proposed, the adjustment factor in the final rule is a ratio of the
declared NOX FELFTP to the FTP NOX
standard to scale the NOX FEL of the other duty cycle or
off-cycle standards.\399\ For example, if a manufacturer declares an
FELFTP of 25 mg NOX/hp-hr in MY 2027 for a Medium
HDE, where the final NOX standard is 35 mg/hp-hr, a ratio of
25/35 or 0.71 will be applied to calculate a FEL to replace each
NOX standard that applies for these engines in the proposed
40 CFR 1036.104(a). Specifically, for this example, a Medium HDE
manufacturer would replace the full useful life standards for SET, LLC,
and the three off-cycle bins with values that are 0.71 of the final
standards. For an SI engine manufacturer that declares an
FELFTP of 15 mg NOX/hp-hr compared to the final
MY 2027 standard of 35 mg/hp-hr, a ratio of 15/35 or 0.43 would be
applied to the SET duty cycle standard to calculate an
FELSET. Note that an FELFTP can also be higher
than the NOX standard in an ABT program if it is offset by
lower-emitting engines in an engine family that generates equivalent or
more credits in the averaging set (see 40 CFR 1036.710). For a FEL
higher than the NOX standard, the adjustment factor will
proportionally increase the emission levels allowed when manufacturers
demonstrate compliance over the other applicable cycles. Manufacturers
are required to set the FEL for credit generation such that the engine
family's measured emissions are at or below the respective FEL of all
the duty-cycle and off-cycle standards. For instance, if a CI engine
manufacturer demonstrates NOX emissions on the FTP that is
25 percent lower than the standard but can only achieve 10 percent
lower NOX emissions for the low load cycle, the declared FEL
could be no less than 10 percent below the FTP standard, to ensure the
proportional FELLLC would be met.
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\397\ The FELs serves as the emission standard for compliance
testing instead of the standards specified in 40 CFR 1036.104(a);
the manufacturer agrees to meet the FELs declared whenever the
engine is tested over the applicable duty- or off-cycle test
procedures.
\398\ See the proposed rule preamble (87 FR 17550, March 28,
2022) for discussion on the relationship between the current FTP
standards and other duty- or off-cycle standards.
\399\ As proposed, we will require manufacturers to declare the
NOX FEL for the FTP duty cycle in their application for
certification. Manufacturers and EPA will calculate FELs for the
other applicable cycles using the procedures specified in 40 CFR
1036.104(c)(3) to evaluate compliance with the other cycles;
manufacturers will not be required to report the calculated FELs for
the other applicable cycles. As noted previously, manufacturers will
demonstrate they meet the standards for PM, CO, and HC and will not
calculate or report FELs for those pollutants.
---------------------------------------------------------------------------
In the final program, manufacturers will include test results in
the certification application to demonstrate their engines meet the
declared FEL values for all applicable duty cycles (see 40 CFR
1036.240(a), finalized as proposed). For off-cycle standards, we are
also finalizing as proposed the requirement for manufacturers to
demonstrate that all the CI engines in the engine family comply with
the final off-cycle emission standards (or the corresponding FELs for
the off-cycle bins) for all normal operation and use by describing in
sufficient detail any relevant testing, engineering analysis, or other
information (see 40 CFR 1036.205(p)). These same bin standards (or
FELs) apply for the in-use testing provisions finalized in 40 CFR part
1036, subpart E, and for the PEM-based DF verification in the finalized
40 CFR 1036.246(b)(2), if applicable.\400\ In addition, as discussed in
Section III, we are finalizing a compliance margin for Heavy HDE to
account for additional variability that can occur in-use over the
useful life of HHDEs; the same 15 mg/hp-hr in-use compliance margin for
HHDEs will be added to declared FELs when verifying in-use compliance
for each of the duty-cycles (i.e., compliance with duty-cycle standards
once the engine has entered commerce) (see 40 CFR 1036.104(a)).
Similarly, the same in-use compliance margin will be applied when
verifying in-use compliance over off-cycle standards (see preamble
Section III.C for discussion).
---------------------------------------------------------------------------
\400\ We did not propose and are not finalizing off-cycle
standards for SI engines; if EPA requests SI engine manufacturers to
perform PEMS-based DF verification as set forth in the final 40 CFR
1036.246(b)(2), then the SI engine manufacturer would use their FEL
to calculate the effective in-use standard for those procedures.
---------------------------------------------------------------------------
Once FEL values are established, credits are calculated based on
the FTP duty cycle. We did not propose substantive revisions to the
equation that applies for calculating emission credits in 40 CFR
1036.705, but we are finalizing, as proposed, to update the variable
names and descriptions to apply for both GHG and criteria pollutant
calculations.\401\ In Equation IV-1, we reproduce the equation of 40
CFR 1036.705 to emphasize how the FTP duty cycle applies for
NOX credits. Credits are calculated as megagrams (i.e.,
metric tons) based on the emission rate over the FTP cycle. The
emission credit calculation represents the emission impact that would
occur if an engine operated over the FTP cycle for its full useful
life. The difference between the FTP standard and the FEL is multiplied
by a conversion factor that represents the average work performed
[[Page 4392]]
over the FTP duty cycle to get the per-engine emission rate over the
cycle. This value is then multiplied by the production volume of
engines in the engine family and the applicable useful life mileage.
Credits are calculated at the end of the model year using actual U.S.
production volumes for the engine family. The credit calculations are
submitted to EPA as part of a manufacturer's ABT report (see 40 CFR
1036.730).
---------------------------------------------------------------------------
\401\ The emission credits equations in the final 40 CFR
1036.705 and the current 40 CFR 86.007-15(c)(1)(i) are functionally
the same.
[GRAPHIC] [TIFF OMITTED] TR24JA23.001
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Where:
StdFTP = the FTP duty cycle NOX emission
standard, in mg/hp-hr, that applies for engines not participating in
the ABT program
FEL = the engine family's FEL for NOX, in mg/hp-hr.
WorkFTP = the total integrated horsepower-hour over the
FTP duty cycle.
MilesFTP = the miles of the FTP duty cycle. For Spark-
ignition HDE, use 6.3 miles. For Light HDE, Medium HDE, and Heavy
HDE, use 6.5 miles.
Volume = the number of engine eligible to participate in the ABT
program within the given engine family during the model year, as
described in 40 CFR 1036.705(c).
UL = the useful life for the standard that applies for a given
engine family, in miles.
We did not receive specific comments on the proposed approach to
calculate a NOX FEL for the other applicable cycles by
applying an adjustment factor based on the declared FELFTP.
As such, we are finalizing the approach as proposed.
3. Averaging Sets
After consideration of public comments, we are finalizing, as
proposed, to allow averaging, banking, and trading only within
specified ``averaging sets'' for heavy-duty engine emission standards.
Specifically, the final rule will use engine averaging sets that
correspond to the four primary intended service classes,\402\ namely:
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\402\ Primary intended service class is defined in 40 CFR
1036.140, which is referenced in the current 40 CFR 86.004-2.
Spark-ignition HDE
Light HDE
Medium HDE
Heavy HDE
Some commenters urged EPA to allow manufacturers to move credits
between the current averaging sets (e.g., credits generated by medium
heavy-duty engines could be used by heavy heavy-duty engines), while
other commenters recommended that EPA finalize the proposal to maintain
restrictions that do not allow movement of credits between the current
averaging sets. Those supporting movement of credits between averaging
sets stated that doing so would reduce the likelihood that a
manufacturer would develop two engines to address regulatory
requirements when they could invest in only one engine if they were
able to move credits between averaging sets; commenters also stated
that restrictions on ABT decrease a manufacturer's ability to respond
to changes in emissions standards. Those supporting the current
restrictions that do not allow movement of credits between averaging
sets stated that maintaining the averaging sets was important to avoid
competitive disruptions between manufacturers.
EPA agrees that maintaining the current averaging sets is important
to avoid competitive disruptions between manufacturers; this is
consistent with our current and historical approach to avoid creating
unfair competitive advantages or environmental risks due to credit
inconsistency.\403\ As described throughout this Section IV.G, we
believe that the final ABT program, including this limitation,
appropriately balances providing manufacturers with flexibility in
their product planning, while maintaining the expected emissions
reductions from the program. As we describe further in Section IV.G.7,
we provide one exception to this limitation for one of the Transitional
Credit pathways for reasons special to that program.\404\
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\403\ 55 FR 30585, July 26, 1990, 66 FR 5002 January 18, 2001
and 81 FR 73478 October 25, 2016.
\404\ As discussed in Section IV.G.7, one of the transitional
credit pathways we are finalizing allows limited movement of
discounted credits between a subset of averaging sets. The
combination of discounting credits moved between averaging sets
combined with the additional limitations included in this
transitional pathway are intended to address the potential for
competitive disadvantages or environmental risks from allowing
credit movement between averaging sets.
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4. FEL Caps
As proposed, the final ABT program includes Family Emissions Limit
(FEL) caps; however, after further consideration, including
consideration of public comments, we are choosing to finalize lower FEL
caps than proposed. The FEL caps in the final rule are 65 mg/hp-hr for
MY 2027 through 2030, and 50 mg/hp-hr for MY 2031 and later (see 40 CFR
1036.104(c)(2)). In this section, IV.G.4, we briefly summarize our
proposed FEL caps, stakeholder comments on the proposed FEL caps, and
then discuss EPA's responses to comments along with our rationale for
the FEL caps in the final rule.
We proposed maximum NOX FELFTP values of 150
mg/hp-hr under both proposed Option 1 (for model year 2027 through
2030), and proposed Option 2 (for model year 2027 and later). This
value is consistent with the average NOX emission levels
achieved by recently certified CI engines (see Chapter 3.1.2 of the
RIA). We believed a cap based on the average NOX emission
levels of recent engines would be more appropriate than a cap at the
current standard of 0.2 g/hp-hr (200 mg/hp-hr), particularly when
considering the potential for manufacturers to apply NOX
credits generated from electric vehicles for the first time.\405\ For
MY 2031 and later under Option 1, we proposed a consistent 30 mg/hp-hr
allowance for each primary intended service class added to each full
useful life standard.
---------------------------------------------------------------------------
\405\ Note that the current g/hp-hr emission standards are
rounded to two decimal places, which allow emission levels to be
rounded down by as much as 5 mg/hp-hr (i.e., with rounding the
current standard is 205 mg/hp-hr).
---------------------------------------------------------------------------
We requested comment on our proposed FEL caps, including our
approach to base the cap for MY 2027 through 2030 under Option 1, or MY
2027 and later under Option 2, on the recent average NOX
emission levels. We also requested comment on whether the
NOX FELFTP cap in MY 2027 should be set at a
different value, ranging from the current Federal NOX
standard of approximately 200 mg/hp-hr to the 50 mg/hp-hr standard in
CARB's HD Omnibus rule starting in MY 2024.406 407
[[Page 4393]]
We further requested comment on the proposal to set MY 2031
NOX FEL caps at 30 mg/hp-hr above the full useful life
standards under proposed Option 1. Finally, we requested comment on
whether different FEL caps should be considered if we finalize
standards other than those proposed (i.e., within the range between the
standards of proposed Options 1 and 2) (See 87 FR 17550, March 28,
2022, for additional discussion on our proposed FEL caps and historical
perspective on FEL caps).
---------------------------------------------------------------------------
\406\ California Air Resources Board, ``California Exhaust
Emission Standards and Test Procedures for 2004 and Subsequent Model
Heavy-Duty Diesel Engines and Vehicles,'' August 27, 2020. https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2020/hdomnibuslownox/frob-1.pdf, page 19. Last accessed September 8,
2022.
\407\ EPA is reviewing a waiver request under CAA section 209(b)
from California for the Omnibus rule.
---------------------------------------------------------------------------
Several commenters provided perspectives on the proposed FEL caps.
All commenters urged EPA to finalize a lower FEL cap than proposed;
there was broad agreement that the FEL cap in the final rule should be
100 mg/hp-hr or lower.
One commenter stated that a FEL cap at the level of the current
standard would not meet the CAA 202(a)(3)(A) requirement to set
``standards which reflect the greatest degree of emission reduction
achievable through the application of technology which the
Administrator determines will be available for the model year to which
such standards apply''. Similarly, many commenters stated that EPA
should finalize FEL caps that match the CARB Omnibus FEL caps (i.e.,
100 mg-hp-hr in 2024-2026 for all engine classes; 50 mg/hp-hr in 2027
and later for LHDEs and MHDE and 65 mg/hp-hr in 2027-2030 and 70 mg/hp-
hr in 2031 and later for HHDEs). These commenters argue that aligning
the FEL caps in the EPA final rule with those in the CARB Omnibus would
reflect the technologies available in 2027 and later, and better align
with the CAA 202(a)(3)(A) requirement for standards that reflect the
greatest degree of emission reduction achievable. Commenters provide
several lines of support that the CARB Omnibus FEL caps should provide
the technical maximum for the EPA FEL caps. Namely, commenters stated
that manufacturers will have been producing products to meet CARB
Omnibus standard of 50 mg/hp-hr starting in 2024. They further state
that two diesel engine families have been certified with CA for MY2022
at a FEL of 160 mg/hp-hr, which is only slightly higher than the FEL
EPA proposed under option 1 for MY 2027 and would continue under the
proposed FEL cap until MY2030. Finally, a commenter pointed to SwRI
data showing that 50 mg/hp-hr can be achieved with what the commenter
considers to be ``minor changes to engine configuration.''
Commenters further argue that EPA should not base the FEL cap in
the final rule on the average performance of recently certified engines
since these engines were designed to comply with the current standards,
which were set over 20 years ago, and do not utilize the emissions
controls technologies that would be available in 2027. Commenters
stated that EPA did not consider the extent to which the proposed FEL
cap could adversely affect the emissions reductions expected from the
rule. Commenters note that although EPA has previously set the FEL cap
at the level of the previous standard, the current FEL cap was set
lower than the previous standard due to the 90 percent reduction
between the previous standard and the current standard. Commenters
argue that EPA should similarly set the FEL cap below the current
standard given the same magnitude in reduction between the current and
proposed standards, and the greater level of certainty in the
technologies available to meet the standards in this rule compared to
previous rules.
Other commenters stated that a FEL cap of 100 mg/hp-hr, or between
50 and 100 mg/hp-hr, would help to prevent competitive disruptions.
Additional details on comments received on the proposed FEL caps are
available in section 12.2 of the Response to Comments document.
Our analysis and rationale for finalizing FEL caps of 65 mg/hp-hr
in MY 2027 through 2030, and 50 mg/hp-hr in MY 2031and later includes
several factors. First, we agree with commenters that the difference
between the current (0.2 g/hp-hr) standard and the standards we are
finalizing for MY 2027 and later suggests that FEL caps lower than the
current standard are appropriate to ensure that available emissions
control technologies are adopted. This is consistent with our past
practice when issuing rules for heavy-duty onroad engines or nonroad
engines in which there was a substantial (i.e., greater than 50
percent) difference between the numeric levels of the existing and new
standards (69 FR 38997, June 29, 2004; 66 FR 5111, January 18, 2001).
Specifically, by finalizing FEL caps below the current standards, we
are ensuring that the vast majority of new engines introduced into
commerce include updated emissions control technologies compared to the
emissions control technologies manufacturers use to meet the current
standards.\408\
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\408\ As discussed in Section IV.G.9, we are finalizing an
allowance for manufacturers to continue to produce a small number (5
percent of production volume) of engines that meet the current
standards for a few model years (i.e., through MY 2029); thus, the
vast majority of, but not all, new engines will need to include
updated emissions control technologies compared to those used to
meet today's standards until MY 2031, when all engines will need
updated emissions control technologies to comply with the final
standards. See Section IV.G.9 for details on our approach and
rationale for including this allowance in the final rule.
---------------------------------------------------------------------------
Second, finalizing FEL caps below the current standard is
consistent with comments from manufacturers stating that a FEL cap of
100 mg/hp-hr or between 50 and 100 mg/hp-hr would help to prevent
competitive disruptions (i.e., require all manufactures to make
improvements in their emissions control technologies).
The specific numeric levels of the final FEL caps were also
selected to balance several factors. These factors include providing
sufficient assurance that low-emissions technologies will be introduced
in a timely manner, which is consistent with our past practice (69 FR
38997, June 29, 2004), and providing manufacturers with flexibility in
their product planning or assurance against unforeseen emissions-
related problems that may arise. In the early years of the program
(i.e., MY2027 through 2030), we are finalizing a FEL cap of 65 mg/hp-hr
to place more emphasis on providing manufacturers flexibility and
assurance against unforeseen emissions control issues in order to
ensure a smooth transition to the new standards and avoid market
disruptions. A smooth transition in the early years of the program will
help ensure the public health benefits of the final program by avoiding
delayed emissions reductions due to slower fleet turnover than may
occur without the flexibility of the final ABT. Thus, the final FEL cap
in MY 2027 through 2030 can help to ensure the expected emissions
reductions by providing manufacturers with flexibility to meet the
final standards through the use of credits up to the FEL cap. In the
later years of the program (i.e., MY 2031 and later), we are finalizing
a FEL cap of 50 mg/hp-hr to place more emphasis on ensuring continued
improvements in the emissions control technologies installed on new
engines.
We disagree with certain commenters stating that a certain numeric
level of the FEL cap does or does not align with the CAA requirement to
set ``standards which reflect the greatest degree of emission reduction
achievable through the application of technology which the
Administrator determines will be available for the model year to which
such standards apply''; rather, given the technology-forcing nature of
the final standards, an optional compliance
[[Page 4394]]
pathway, including the FEL caps and other elements of the ABT program,
through the final rule is consistent with requirements under CAA
section 202(a)(3)(A).\409\ Nevertheless, as described in this Section
IV.G.4, we are finalizing lower FEL caps than proposed as part of a
carefully balanced final ABT program that provides flexibilities for
manufacturers to generate NOX emissions credits while
assuring that available emissions control technologies are adopted and
the emissions reductions expected from the final program are realized.
---------------------------------------------------------------------------
\409\ See NRDC v. Thomas, 805 F. 2d 410, 425 (D.C. Cir. 1986)
(upholding averaging as a reasonable and permissible means of
implementing a statutory provision requiring technology-forcing
standards).
---------------------------------------------------------------------------
Finally, we disagree with commenters stating a FEL cap can
adversely affect the emissions reductions expected from the final rule.
Inherent in the ABT program is the requirement for manufacturers
producing engines above the emissions standard to also produce engines
below the standard or to purchase credits from another manufacturer who
has produced lower emitting engines. As such, while the FEL cap
constrains the extent to which engines can emit above the level of the
standard, it does not reduce the expected emissions reductions because
higher emitting engines must be balanced by lower emitting engines.
Without credit multipliers, an ABT program, and the associated FEL cap,
may impact when emissions reductions occur due to manufacturers
choosing to certify some engines to a more stringent standard and then
later use credits generated from those engines, but it does not impact
the absolute value of the emissions reductions. Rather, to the extent
that credits are banked, there would be greater emissions reductions
earlier in the program, which leads to greater public health benefits
sooner than would otherwise occur; as discussed earlier in this Section
IV.G, benefits realized in the near term are worth more to society than
those deferred to a later time.
The FEL caps for the final rule have been set at a level to ensure
sizeable emission reductions from the existing 2010 standards, while
providing manufacturers with flexibility to meet the final standards.
When combined with the other restrictions in the final ABT program
(e.g., credit life, averaging sets, expiration of existing credit
balances), we believe the final FEL caps of 65 mg/hp-hr in MY 2027
through 2030, and 50 mg/hp-hr in MY 2031 and later avoid potential
adverse effects on the emissions reductions expected from the final
program.
5. Credit Life for MY 2027 and Later Credits
As proposed, we are finalizing a five-year credit life for
NOX emissions credits generated and used in MY 2027 and
later, which is consistent with the existing credit life for
CO2. In this section, IV.G.5, we briefly summarize our
proposed credit life, stakeholder comments on the proposed credit life,
and then discuss EPA's responses to comments along with our rationale
for credit life in the final rule. Section IV.G.7 discusses credit life
of credits generated in MYs 2022 through 2026 for use in 2027.
We proposed to update the existing credit life provisions in 40 CFR
1036.740(d) to apply for both CO2 and NOX
credits. The proposal updated the current unlimited credit life for
NOX credits such that NOX emission credits
generated for use in MY 2027 and later could be used for five model
years after the year in which they are generated.\410\ For example,
under the proposal credits generated in model year 2027 could be used
to demonstrate compliance with emission standards through model year
2032. We also requested comment on our proposed five-year credit life.
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\410\ As discussed in Section IV.G.10, we are not finalizing the
proposed allowance for manufacturers to generate credits from BEVs
or FCEVs, and thus the credit life provisions in 40 CFR 1036.740(d)
do not apply to BEVs or FCEVs.
---------------------------------------------------------------------------
Several commenters provided perspectives on the proposal to revise
the credit life of NOX emissions credits from unlimited to
five years. Commenters took several different positions, including
supporting the proposed five-year credit life, arguing that three
years, not five, is the more appropriate credit life period, and
arguing that credit life should be unlimited. Additional details and a
summary of comments received on the proposed credit life are available
in section 12 of the Response to Comments document.
The commenter supporting the proposed five-year credit life, rather
than an unlimited credit life, states that they conducted an analysis
that showed manufacturers had accrued credits from 2007-2009 MYs, which
could have been used to certify engines up to the FEL cap in the
Omnibus 2024-2026 program and would have delayed emissions reductions
in those years. They further state that unlimited credit life would
allow manufacturers to produce higher emitting engines against more
stringent standards for many years (e.g., in MY2030).
The commenter arguing that three (not five) years is an appropriate
credit life to average out year-to-year variability stated that three
years aligns with the CAA requirement for three years of stability
between changes in standards, and it represents the pace of improvement
that manufacturers include in their product planning. The commenter
argues that three years would be more protective under the CAA and is
the duration that EPA previously used for NOX and PM
emissions credits. Finally, the commenter states that EPA has not
justified its choice of five years.
Commenters who urged EPA to finalize an unlimited credit life for
NOX emissions credits did not provide data or rationale to
support their assertion.
After further consideration, including consideration of public
comments, EPA is finalizing as proposed a five-year credit life for
credits generated and used in MY 2027 and later. The credit life in the
final rule is based on consideration of several factors. First,
consistent with our proposal, we continue to believe a limited credit
life, rather than an unlimited credit life suggested by some
commenters, is necessary to prevent large numbers of credits
accumulating early in the program from interfering with the incentive
to develop and transition to other more advanced emissions control
technologies later in the program. Further, as discussed in Section
IV.G.7, we believe the transitional credit program in the final rule
addresses key aspects of manufacturers' requests for longer credit
life. Second, as explained in the proposal, we believe a five-year
credit life adequately covers a transition period for manufacturers in
the early years of the program, while continuing to encourage
technology development in later years.
We disagree with one commenter who stated that a three-year credit
life is more appropriate than a five-year credit life. Rather, we
believe five years appropriately balances providing flexibility in
manufacturers product planning with ensuring available emissions
control technologies are adopted. Further, as discussed in Section
IV.G.4, inherent in an ABT program is the requirement for manufacturers
producing engines above the emissions standard to also produce engines
below the standard or to purchase credits from another manufacturer who
has produced lower emitting engines. As such, while the five-year
credit life in the final rule constrains the time period over which
manufacturers can use credits, it does not impact the overall emissions
[[Page 4395]]
reductions from the final rule. In addition, to the extent that credits
are banked for five-years, the emissions reductions from those credits
occur five-years earlier, and as discussed earlier in this Section
IV.G, benefits realized in the near term are worth more to society than
those deferred to a later time. Finally, a five-year credit life is
consistent with our approach in the existing light-duty criteria and
GHG programs, as well as our heavy-duty GHG program (see 40 CFR
86.1861-17, 86.1865-12, and 1037.740(c)).
As discussed in Section IV.G.7, we are finalizing a shorter credit
life for credits generated in 2022 through 2026 with engines certified
to a FEL below the current MY 2010 emissions standards, while complying
with all other MY 2010 requirements, since these credits are generated
from engines that do not meet the MY 2027 and later requirements. We
are also finalizing longer credit life values for engines meeting all,
or some of the key, MY 2027 and later requirements to further
incentivize emissions reductions before the new standards begin (see
IV.G.7 for details).
6. Existing Credit Balances
After further consideration, including information received in
public comments, the final rule will allow manufacturers to generate
credits in MYs 2022 and later for use in MYs 2027 and later, as
described further in the following Section IV.G.7. Consistent with the
proposal, in the final program, manufacturers will not be allowed to
use credits generated prior to model year 2022 when certifying to model
year 2027 and later requirements.
We proposed that while emission credits generated prior to MY 2027
could continue to be used to meet the existing emission standards
through MY 2026 under 40 CFR part 86, subpart A, those banked credits
could not be used to meet the proposed MYs 2027 and later standards
(except as specified in 1036.150(a)(3) for transitional and early
credits in 1036.150(a)(1) and (2)). Our rationale included that the
currently banked NOX emissions credits are not equivalent to
credits that would be generated under the new program (e.g., credits
were generated without demonstrating emissions control under all test
conditions of the new program), and that EPA did not rely on the use of
existing credit balances to demonstrate feasibility of the proposed
standards.
Some commenters urged EPA to allow the use of existing credits, or
credits generated after the release of the CTI ANPR, to be used in MYs
2027 and later. Commenters stated that EPA has not demonstrated the
standards are feasible without the use of credits, and that the credits
were from engines with improved emissions that provide real-world
NOX benefits, even if they are not certified to all of the
test conditions of the proposed program. They further stated that not
allowing the use of existing credits in 2027 and later could discourage
manufacturers from proactively improving emissions performance. In
contrast, other commenters support the proposal to discontinue the use
of old credits (e.g., those generated before 2010) since allowing the
use of these credits would delay emissions reductions and prevent a
timely transition to new standards.
EPA did not rely on the use of existing or prior to MY 2027 credit
balances to demonstrate feasibility of the proposed standards (see
Section III) and continues to believe that credits from older model
years should not be used to meet the final MY 2027 and later standards.
Credits from older model years (i.e., MY 2009 or prior) were generated
as manufacturers transitioned to the current standards, and thus would
not require manufacturers to introduce new emissions control
technologies to generate credits leading up to MY 2027. However, EPA
agrees with some commenters that credits generated in model years
leading up to MY 2027 are from engines with improved emissions controls
and provide some real-world NOX benefits, even if they are
not certified to all of the test conditions of the model year 2027 and
later program. Therefore, the transitional credit program we are
finalizing allows manufacturers to generate credits starting in model
year 2022 for use in MYs 2027 and later; however, credits generated
from engines in MYs 2022-2026 that do not meet all of the MY 2027 and
later requirements are discounted to account for the differences in
emissions controls between those engines and engines meeting all 2027
and later requirements (see Section IV.G.7 and Section 12 of the RTC
for details). For credits generated in model years prior to MY 2022, we
are finalizing that such emission credits could continue to be used to
meet the existing emission standards through MY 2026 under 40 CFR part
86, subpart A.
We selected model year 2022 for two reasons. First, allowing MY
2022 and later credits inherently precludes emissions credits from the
oldest model years (i.e., MY 2009 or prior). These oldest years are
when the vast majority of existing credit balances were accumulated, to
create flexibility in transitioning to the MY 2007-2010 standards.\411\
The oldest model year credits were not generated with current emissions
control technologies and are therefore quite distinct from credits
generated under the final standards. Second, regarding both the oldest
MY credits and those few generated in more recent years, allowing only
MY 2022 and later credits incentivizes manufacturers to maximize their
development and introduction of the best available emissions control
technologies ahead of when they are required to do so in MY2027. As
discussed in IV.G.7, this not only provides a stepping-stone to the
broader introduction of this technology soon thereafter, but also
encourages the early production of cleaner vehicles, which enhances the
early benefits of our program. If we were to allow manufacturers to use
emissions credits from older model years then there would be no
incentive to apply new emissions control technologies in the years
leading up to MY 2027. Further, we recognize that some manufacturers
have begun to modernize some of their emissions controls in
anticipation of needing to comply with the CARB Omnibus standards that
begin in 2024,\412\ or potential future Federal standards under this
final rule, and agree with commenters that it's appropriate to
recognize the effort to proactively improve emissions performance.\413\
Thus, allowing credits generated in MY 2022 and later both recognizes
improvements in emissions controls beyond what is needed to meet the
current standards, and ensures that only credits generated in the model
years leading up to 2027 can be used to meet the standards finalized in
this rule.
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\411\ EPA compliance data shows that prior to MY 2022, the
majority of heavy-duty on-highway engine manufacturers were not
generating NOX emissions credits in recent model years
(i.e., since model year 2009).
\412\ EPA is reviewing a waiver request under CAA section 209(b)
from California for the Omnibus rule.
\413\ As discussed in this Section IV.G, the final ABT program
does not allow manufacturers to generate emissions credits from
engines certified to state emission standards that are different
than the federal standards; however, as discussed in IV.G.7,
manufacturers could generate emissions credits if they produce
larger volumes of engines to sell outside of those states that have
adopted emission standards that are different than the federal
standards.
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7. Transitional Credits Generated in MYs 2022 Through 2026
We are finalizing a transitional credit program that includes
several pathways for manufacturers to generate transitional credits in
MYs 2022 through 2026 that they can then use in MYs 2027 and later. The
transitional credit pathways differ in several ways from
[[Page 4396]]
what we proposed based on further consideration, including the
consideration of public comments. In this section, IV.G.7, we briefly
summarize our proposed transitional credit program, stakeholder
comments on the proposed transitional credit program, and then discuss
EPA's responses to comments along with our rationale for the
transitional credit pathways in the final rule.
Under the proposed transitional credit program, manufacturers would
generate transitional credits in model years 2024 through 2026. As
proposed, manufacturers would have calculated transitional credits
based on the current NOX emissions standards and useful life
periods; however, manufacturers would have been required to certify to
the other model year 2027 and later requirements, including the LLC and
off-cycle test procedures. We proposed the same five-year credit life
for transitional credits as other credits in the proposed general ABT
program (see 87 FR 17553-17554 March 28, 2022, for additional details
of the proposed transitional credits).
We requested comment on our proposed approach to offer transitional
NOX emission credits that incentivize manufacturers to adopt
the proposed test procedures earlier than required in MY 2027. We also
requested comment on whether CI engines should be required to meet the
proposed off-cycle standards to qualify for the transitional credits,
and were specifically interested in comments on other approaches to
calculating transitional credits before MY 2027 that would account for
the differences in our current and proposed compliance programs. In
addition, we requested comment on our proposed five-year credit life
for transitional NOX emission credits. Finally, we also
requested comment related to our proposed Early Adoption Incentives on
whether EPA should adopt an incentive that reflects the MY 2024 Omnibus
requirements being a step more stringent than our current standards,
but less comprehensive than the proposed MY 2027 requirements.
Several commenters provided perspectives on the proposed
transitional credit program under the ABT program. Most commenters
either opposed allowing manufacturers to generate NOX
emissions credits, or suggested additional requirements for generating
credits that could be used in MYs 2027 and later. One commenter stated
that due to lead time and resource constraints, manufacturers would not
be able to participate in the proposed transitional credit program.
Another commenter supported the proposed transitional credit program.
One commenter also stated that incentives for compliant vehicles, not
just ZEVs, purchased prior to the MY 2027 will bring tremendous health
benefits to at-risk communities and the nation. Similarly, one
commenter encouraged EPA to further incentivize emissions reductions
prior to the start of the new standards by providing additional
flexibilities to use credits in MY 2027 and later if manufacturers were
able to certify prior to MY 2027 a large volume of engines (i.e., an
entire engine service class) to almost all MY2027 and later
requirements.
Commenters who opposed allowing manufacturers to generate
NOX emissions credits prior to MY2027 were concerned that
the difference between Federal and state (i.e., CARB Omnibus) standards
would result in ``windfall of credits'' that would allow a large
fraction of engines to emit at the FEL cap into MY2030 and later. One
commenter stated that EPA has not adequately assessed the potential
erosion of emissions reductions from credits generated by engines
certifying to the CARB Omnibus standards. Another commenter stated that
manufacturers are already certifying to levels below the current MY2010
standards, and they believe that certifying to the new test procedures
will take little effort for manufacturers. The commenter stated that
there is no need to incentivize manufacturers to adopt proposed test
procedures ahead of MY2027 because they will already be doing so under
the Omnibus program. They argued that rather than requiring new
testing, EPA should encourage new technology adoption. Commenters
opposing the transitional credit program stated that EPA should
eliminate the transitional credit program, or if EPA choses to finalize
the transitional credit program, then EPA should adjust the final
standards to account for the transitional credit program impacts, or
revise the transitional credit program (e.g., shorten credit life to
three years, establish a separate bank for credits generated by engines
in states adopting the Omnibus standards). Two commenters stated that
EPA should require engines generating credits prior to 2027 to meet all
of the requirements of 2027 and beyond; they highlighted the importance
of the 2027 and later low-load cycle and off-cycle standards to ensure
real-world reductions on the road, and stated that there should be
consistency in the way credits are generated and the way they are used.
Similarly, these commenters oppose credits for legacy engines or legacy
technologies (i.e., engines or technologies used to meet the current
emissions standards).
The commenter who stated that manufacturers would be unable to
generate credits under the proposed transitional credit due to lead
time and resource constraints argued that manufacturers would be unable
to adjust their engine development plans to meet the new LLC and off-
cycle test standards in MY 2024. They further stated that in many cases
deterioration factor (DF) testing has already started for MY 2024
engines. The commenter also argued that they view the ABT program as
part of the emissions standards, and the proposed transitional credit
program provided less than the four-year lead time that the CAA
requires when setting heavy-duty criteria pollutant emissions
standards. In addition, the commenter stated that the proposed
transitional credit program would disincentivize manufacturers to make
real-world NOX emissions reductions ahead of when new
standards are in place because they would not be able to design and
validate their engines to meet the requirements to generate credits.
Finally, a commenter suggested EPA further encourage additional
emissions reductions prior to the start of new standards by providing
greater flexibility to use credits in MYs 2027 and later.\414\
Specifically, this commenter suggested that EPA provide a longer credit
life (e.g., ten years compared to the five years proposed for the ABT
program) and also allow the movement of credits between averaging sets.
The commenter stated that in order to generate credits with these
additional flexibilities manufacturers would need to certify an entire
engine service class (e.g., all heavy heavy-duty engines a manufacturer
produced) in a given model year to a FEL of 50 mg/hp-hr or less, and
meet all other MY 2027 and later requirements. They further stated that
it may not be appropriate for natural gas engines to generate credits
with these additional flexibilities since natural gas engines can meet
a 50 mg/hp-hr FEL today. Finally, the commenter stated that engines
using these credits in MYs 2027 and later should be required to certify
to a FEL of 50 mg/hp-hr or less. Additional details on comments
regarding the proposed transitional credit program are included in
section 12 of the Response to Comments document.
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\414\ U.S. EPA. Stakeholder Meeting Log. December 2022.
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After considering comments on the proposed transitional credit
program, we are choosing to finalize a revised
[[Page 4397]]
version of the proposed transitional credit program. Similar to the
proposed rule, we are finalizing an optional transitional credit
program to help us meet our emission reduction goals at a faster pace,
while also providing flexibilities to manufacturers to meet new, more
stringent emission standards. Building on the ABT program as whole, the
transitional credit program in the final rule can benefit the
environment and public health in two ways. First, early introduction of
new emission control technologies can accelerate the entrance of lower-
emitting engines and vehicles into the heavy-duty vehicle fleet,
thereby reducing NOX emissions from the heavy-duty sector
and lowering its contributions to ozone and PM formation before new
standards are in place. Second, the earlier improvements in ambient air
quality will result in public health benefits sooner than they would
otherwise occur; these benefits are worth more to society than those
deferred to a later time, and could be particularly impactful for
communities already overburdened with pollution. As discussed in
Section II, many state and local agencies have asked the EPA to further
reduce NOX emissions, specifically from heavy-duty engines,
because such reductions will be a critical part of many areas'
strategies to attain and maintain the ozone and PM2.5 NAAQS.
Several of these areas are working to attain or maintain NAAQS in
timeframes leading up to and immediately following the required
compliance dates of the final standards, which underscores the
importance of the early introduction of lower-emitting vehicles.
The transitional credit program is voluntary and as such no
manufacturer is required to participate in the transitional credit
program. The transitional credit program in the final rule will provide
four pathways for manufacturers to generate credits in MYs 2022 through
2026 for use in MYs 2027 and later: (1) In MY 2026, certify all engines
in the manufacturer's heavy heavy-duty service class to a FEL of 50 mg/
hp-hr or less and meet all other EPA requirements for MYs 2027 and
later to generate undiscounted credits that have additional
flexibilities for use in MYs 2027 and later (2026 Service Class Pull
Ahead Credits); (2) starting in MY 2024, certify one or more engine
family(ies) to a FEL below the current MY2010 emissions standards and
meet all other EPA requirements for MYs 2027 and later to generate
undiscounted credits based on the longer UL periods included in the
2027 and later program (Full Credits); (3) starting in MY 2024, certify
one or more engine family(ies) to a FEL below the current MY2010
emissions standards and meet several of the key requirements for MYs
2027 and later, while meeting the current useful life and warranty
requirements to generate undiscounted credits based on the shorter UL
period (Partial Credits); (4) starting in MY 2022, certify one or more
engine family(ies) to a FEL below the current MY2010 emissions
standards, while complying with all other MY2010 requirements, to
generate discounted credits (Discounted Credits).
All credits generated in the first pathway have an eight-year
credit life and can therefore be used through MY 2034. All credits
generated under the second or third pathways will expire by MY2033; all
credits generated in the fourth pathway will expire by MY 2030. We
further describe each pathway and our rationale for each pathway in
this section (see the final interim provisions in 40 CFR 1036.150(a)
for additional details).\415\ In Section IV.G.8 we discuss our decision
to finalize the transitional credit pathways in lieu of the proposed
Early Adoption Incentives program (section 12 of the Response to
Comments document includes additional details on the comments received
on the proposed Early Adoption Incentives program).
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\415\ We are finalizing as proposed a requirement that, to
generate transitional NOX emission credits, manufacturers
must meet the applicable PM, HC, and CO emission standards without
generating or using emission credits. For the first and second
pathways, applicable PM, HC, and CO emission standards are in 40 CFR
1036.104. For the third and fourth pathways (Partial and Discounted
Credits), applicable PM, HC, and CO emission standards are in 40 CFR
86.007-11 or 86.008-10.
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In developing the final transitional credit program and each
individual pathway, we considered several factors. For instance, for
the transitional credit program as a whole, one commenter stated that
there should be consistency in the way the credits are generated and
the way they are used; several commenters urged EPA to only provide
transitional credits to engines meeting all the 2027 and later
requirements. The transitional credit program acknowledges these
commenters' input by only providing full credit value to engines
meeting all the 2027 and later requirements [i.e., 2026 Service Class
Pull Ahead Credits and Full Credits pathways], while providing a lesser
value for credits generated from engines that do not meet all of the
2027 and later requirements but still demonstrate improved emissions
performance compared to the current standards.
We now turn to discussing in detail each pathway, and the factors
we considered in developing each pathway. The first pathway
acknowledges the significant emissions reductions that would occur if
manufacturers were to certify an entire service class of heavy heavy-
duty engines to a much lower numeric standard than the current
standards and meet all other MY 2027 requirements prior to the start of
the new standards. Specifically, compared to the emissions reductions
expected from the final rule, our assessment shows significant,
additional reductions in the early years of the program from certifying
the entire heavy heavy-duty engine fleet to a FEL of 50 mg/hp-hr or
less and meeting all other MY2027 requirements in MY 2026, one model
year prior to the start of the new standards.\416\ As discussed
throughout this Section IV.G, emissions reductions, and the resulting
public health benefits, that are realized earlier in time are worth
more to society than those deferred to a later time. Based on the
potential for additional, early emissions reductions, we are finalizing
the 2026 Service Class Pull Ahead Credits pathway with two additional
flexibilities for manufacturers to use the credits in MYs 2027 and
later. First, 2026 Service Class Pull Ahead Credits have an eight-year
credit life (i.e., expire in MY 2034), which is longer than credits
generated in the other transitional credit pathways, or under the main
ABT program. Second, we are allowing 2026 Service Class Pull Ahead
Credits to move from a heavy heavy-duty to a medium heavy-duty
averaging set; however, credits moved between averaging sets will be
discounted at 10 percent. We note that a recent assessment by an
independent NGO shows that allowing credits to move between service
classes could reduce the overall monetized health benefits of a program
similar to the one in this final rule; however, the 10 percent discount
rate that we are apply would more than offset the potential for reduced
emissions reductions. Moreover, as noted in this section, the early
emissions reductions from this transitional credit program would
provide important positive benefits, particularly in communities
[[Page 4398]]
overburdened with pollution.\417\ Further, we are balancing these
additional flexibilities with restrictions on which engines can
participate in the 2026 Service Class Pull Ahead Credits pathway.
Specifically, only heavy heavy-duty engines may generate 2026 Service
Class Pull Ahead Credits; we expect a much lower level of investment
would be required for natural gas-fueled engines, light heavy-duty
engines, and SI engines to meet the 2026 Service Class Pull Ahead
Credits requirements compared to the investment needed for heavy-
heavy-duty engines. We expect that the combination of discounting
credits moved across averaging sets and only allowing the heavy heavy-
duty engine service class to participate in the 2026 Service Class Pull
Ahead Credits pathway will appropriately balance the potential for
meaningful emissions reductions in the early years of the program with
the potential for adverse competitive disadvantages or environmental
risks from either unequal investments to generate credits or producing
large volumes of credits from engines that could easily meet the
requirements of the 2026 Service Class Pull Ahead Credits pathway.
Finally, engines certified using 2026 Service Class Pull Ahead Credits
in 2027 through 2034 will need to meet a FEL of 50 mg/hp-hr or less;
this requirement helps to ensure that these credits are used only to
certify engines that are at least as low emitting as the engines that
generated the credits.
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\416\ See RIA Chapter 5.5.5 for additional details on our
assessment of emissions reductions projected to occur from
certifying engines to a FEL of 50 mg/hp-hr and meeting all other
2027 requirements in MY 2026. Note that for the purposes of bounding
the potential emissions impacts, we assumed all heavy heavy-duty
engines would participate in the 2026 Service Class Pull Ahead
Credits pathway, and that those credits would be used by both medium
and heavy heavy-duty engines in MY 2027 and later, until
manufacturers used all of the credits.
\417\ See U.S. EPA. Stakeholder Meeting Log. December 2022 for
details of the assessment by the independent NGO (ICCT).
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The second pathway (Full Credits) acknowledges the emissions
reductions that could be achieved prior to the start of new standards
if manufacturers certify to a FEL lower than today's standard and meet
all other MY 2027 and later requirements, although without doing so for
an entire engine service class. This pathway is similar to our proposed
transitional credit program and is consistent with input from
commenters who highlighted the importance of meeting MY 2027 and later
requirements such as the low-load cycle and off-cycle standards to
ensure real-world reductions on the road. As proposed, all heavy-duty
engine service classes, including heavy-duty natural gas engines in the
respective service classes, can participate in this pathway.
The third pathway (Partial Credits) incentivizes manufacturers to
produce engines that meet several of the key final requirements for MY
2027 and later, including the LLC and off-cycle standards for
NOX, while meeting the existing useful life and warranty
periods.\418\ This pathway allows manufacturers to adopt new emissions
control technologies without demonstrating durability over the longer
useful life periods required in MY 2027 and later, or certifying to the
longer warranty periods in the final rule. We expect that some
manufacturers may already be planning to produce such engines in order
to comply with 2024 California Omnibus program; however, this
transitional pathway would incentivize manufacturers to produce greater
volumes of these engines than they would otherwise do to comply in
states adopting the Omnibus standards. Some commenters were concerned
that the proposed transitional credit program would result in
``windfall credits'' due to manufacturers generating credits from
engines produced to comply with more stringent state standards. As
discussed in IV.G, the final program will not allow manufacturers to
generate credits from engines certified to meet state standards that
are different from the Federal standards.\419\ The Partial Credits
pathway thus avoids ``windfall credits'' because manufacturers are not
allowed to generate credits from engines produced to meet the more
stringent 2024 Omnibus requirements, but rather are incentivized to
produce cleaner engines that would benefit areas of the country where
such engines may not otherwise be made available (i.e., outside of
states adopting the Omnibus program).\420\ Further, because engines
participating in this pathway will be certified to shorter useful life
periods, they will generate fewer credits than engines participating in
the third and fourth pathways (Full Credits and 2026 Service Class Pull
Ahead Credits).
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\418\ Engines earning Partial Credits must comply with
NOX standards over the Low Load Cycle and the off-cycle
standards. The family emission limits for the Low Load Cycle and
off-cycle standards are calculated relative to the family emission
limit the manufacturer declares for FTP testing, as described in 40
CFR 1036.104(c). If we direct a manufacturer to do in-use testing
for an engine family earning Partial Credits, we may direct the
manufacturer to follow either the in-use testing program specified
in 40 CFR part 1036 for NOX, or the in-use testing
program in 40 CFR part 86 for all criteria pollutants. Except for
the NOX standards for the Low Load Cycle and for off-
cycle testing, engines generating Partial Credits would be subject
to all the certification and testing requirements from 40 CFR part
86.
\419\ See final part 1036, subpart H, and 40 CFR 1036.801 (which
EPA did not propose any revisions to in the proposed migration from
part 86, subpart A, to part 1036). See also the substantively
similar definition of U.S.-directed production in current 40 CFR
86.004-2. Under 40 CFR 1036.705(c), which we are also finalizing as
proposed as applicable for NOX ABT, compliance through
ABT does not allow credit calculations to include engines excluded
from the definition of U.S.-directed production volume: ``As
described in Sec. 1036.730, compliance with the requirements of
this subpart is determined at the end of the model year based on
actual U.S.-directed production volumes. Keep appropriate records to
document these production volumes. Do not include any of the
following engines to calculate emission credits: . . . (4) Any other
engines if we indicate elsewhere in this part 1036 that they are not
to be included in the calculations of this subpart.''
\420\ EPA is reviewing a waiver request under CAA section 209(b)
from California for the Omnibus rule.
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The first, second, and third pathways all include meeting the LLC
requirements for MY 2027 and later. One commenter suggested meeting the
LLC would require manufacturers to simply meet a lower numeric standard
than the current standard; however, EPA disagrees. Certifying to the
LLC will require more than simply meeting a lower numeric standard
since the LLC is a new test cycle that requires demonstration of
emissions control in additional engine operations (i.e., low load)
compared to today's test cycles (see preamble Section III and section 3
of the Response to Comments document and for more discussion on the
LLC).
Finally, the fourth pathway (Discounted Credits) allows
manufacturers to generate credits for use in MY 2027 and later with
engines that are not designed to meet the LLC and off-cycle standards
and so could provide additional compliance flexibility for meeting the
final standards; however, since the engines are not meeting the full
requirements of the MY 2027 and later program the credits are
discounted and will expire before credits generated in the other
transitional credit pathways. This Discounted Credits pathway includes
consideration of input from one commenter who stated that it would be
infeasible for manufacturers to comply with the new LLC and off-cycle
test procedures in MY 2024 in order to generate credits under the
proposed credit program; they further argued that for manufacturers
relying on credits to comply with the final standards, the proposed
transitional credit program would not provide the lead time required by
the CAA. As described in Section III of this preamble, the new
standards in the final rule are feasible without the ABT program and
without the use of transitional credits; participation in ABT is
voluntary and is intended to provide additional flexibility to
manufacturers through an optional compliance pathway. While
manufacturers have the option of generating NOX emissions
credits under the transitional credit program in the final rule, they
are not required to do so. The four-year lead time requirement under
CAA 202(a)(3) does not apply to these ABT provisions.
[[Page 4399]]
Nevertheless, the final rule allows credits generated under this
Discounted Credits pathway to incentivize improvements in emissions
controls, even if the engines are not certified to the full MY2027 and
later requirements. Credits will be discounted by 40 percent to account
for differences in NOX emissions during low-load and off-
cycle operations between current engines and engines certifying to the
model year 2027 and later requirements. While we expect that
manufacturers certifying to a FEL below the current 200 mg/hp-hr
standard will reflect improvement in emissions control over the FTP and
SET duty-cycles, the discount applied to the credits accounts for the
fact that these engines are not required to maintain the same level of
emissions control over all operations of the off-cycle standards, or
during the low-load operations of the LLC. For example, a manufacturer
certifying a HHDE engine family to a FEL of 150 mg/hp-hr and all other
MY 2010 requirements with a U.S.-directed production volume of 50,000
engines in 2024 would generate approximately 5,000 credits (see
Equation IV-1), which they would then multiply by 0.6 to result in a
final credit value of 3,000 credits. See the final, revised from
proposal, interim provision in 40 CFR 1036.150(a)(1) for additional
details on the calculation of discounted credits.
Credits generated under this Discounted Credits pathway could be
used in MY 2027 through MY 2029. The combination of the discount and
limited number of model years in which manufacturers are allowed to use
these credits is consistent with our past practice and helps to
addresses some commenters' concerns about allowing legacy engines to
generate credits, or credits generated under the transitional credit
program eroding emissions reductions expected from the rule (55 FR
30584-30585, July 26,1990). There are two primary ways that the
Discounted Credits pathway results in positive public health impacts.
First, an immediate added benefit to the environment is the discounting
of credits, which ensures that there will be a reduction of the overall
emission level. The 40 percent discount provides a significant public
health benefit, while not being so substantial that it would discourage
the voluntary initiatives and innovation the transitional ABT program
is designed to elicit. Second, consistent with the benefits of the
overall transitional credit program, when the ``time value'' of
benefits (i.e., their present value) is taken into account, benefits
realized in the near term are worth more to society than those deferred
to a later time. The earlier expiration date of credits in the
Discounted Pathway reflects that these credits are intended to help
manufacturers transition in the early years of the program, but we
don't think they are appropriate for use in later years of the program.
The earlier expiration of credits is also consistent with comments that
we should finalize a 3-year credit life for transitional credits (i.e.,
credits can be used for 3-years once the new standards begin).
As discussed earlier in this Section IV.G.7, credits generated
under the first pathway (2026 Service Class Pull Ahead Credits) can be
used for eight years, through MY 2034; we selected this expiration date
to balance incentivizing manufacturers to participate in the 2026
Credits pathway and thereby realize the potential for additional, early
emissions reductions, with continuing to encourage the introduction of
improved emissions controls, particularly as the heavy-duty fleet
continues to transition into zero emissions technologies.\421\ As
stated in the preceding paragraphs, all credits generated in the second
and third pathways can be used through MY 2032. Our rationale for this
expiration date is two-fold. First, providing a six-year credit life
from when the new standards begin provides a longer credit life than
provided in the final ABT program for credits generated in MY 2027 and
later; similar to the first pathway, this longer credit life
incentivizes manufacturers to produce engines that emit lower levels of
NOX earlier than required. Second, the six-year credit life
balances additional flexibility for manufacturers to transition over
all of their product lines with the environmental and human health
benefits of early emissions reductions. This transitional period
acknowledges that resource constraints may make it challenging to
convert over all product lines immediately when new standards begin,
but maintains emission reductions projected from program by requiring
the use of credits to certify engines that emit above the level of the
new standard. While some commenters stated that manufacturers will have
been complying with the CARB Omnibus program starting in 2024, we
acknowledge that complying with the 2027 and later Federal standards
will require another step in technology and thus think it is
appropriate to provide additional flexibility for manufacturers to
transition to the new standards through the use of emissions credits in
the ABT program.
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\421\ As discussed in RIA 5.5.5, our evaluation shows that
manufacturers would use all 2026 Service Class Pull Ahead Credits in
about an eight-year period, which further supports the eight-year
credit life of the 2026 Service Class Pull Ahead Credits pathway.
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This section describes how to generate credits for MY 2026 and
earlier engines that are certified to standards under 40 CFR part 86,
subpart A. As noted in Section III.A.3, we are allowing manufacturers
to continue to certify engines to the existing standards for the first
part of model year 2027. While those engines continue to be subject to
standards under 40 CFR part 86, subpart A, we are not allowing those
engines to generate credits that carry forward for certifying engines
under 40 CFR part 1036.\422\ Manufacturers may only generate
NOX emissions credits under transitional credit pathways for
MY 2024-2026 engines since one purpose of transitional credits is to
incentivize emission reductions in the model years leading up to MY
2027. To the extent manufacturers choose to split MY 2027, the engines
produced in the first part of the split MY are produced very close in
time to when the new standards will apply, and thus we expect that
rather than incentivizing earlier emission reductions, providing an
allowance to generate NOX emission credits would incentivize
production at higher volumes during the first part of the split MY than
would otherwise occur (i.e., incentivizing more of the MY 2027
production before the final standards apply). The higher production
volume of engines in the first part of the split MY could thereby
result in additional NOX emission credits without additional
emission reductions that would otherwise occur. See preamble Section
III.A.3 for details on the split model year provision in this final
rule.
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\422\ MY 2027 engines produced prior to four years after the
date that the final rule is promulgated and certified to the
existing 40 CFR part 86 standards cannot participate in the part
1036 ABT program; however, MY 2027 engines certified to 40 CFR part
1036 standards and requirements may participate in the ABT program
specified in 40 CFR part 1036, subpart H.
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8. Early Adoption Incentives
EPA is choosing not to finalize the Early Adoption Incentives
program as proposed. This includes a decision not to include emissions
credit multipliers in the final ABT program. Rather, we are finalizing
a revised version of the transitional credit program under the ABT
program as described above in Section IV.G.7. In this Section IV.G.8 we
briefly describe the proposed Early Adoption Incentives program,
stakeholder comments on the proposed Early Adoption Incentives program,
and then discuss EPA's responses to comments along with our rationale
for
[[Page 4400]]
choosing not to finalize the Early Adoption Incentives program.
We proposed an early adoption incentive program that would allow
manufacturers who demonstrated early compliance with all of the final
MY 2027 standards (or MY 2031 standards under proposed Option 1) to
include Early Adoption Multiplier values of 1.5 or 2.0 when calculating
NOX emissions credits. In the proposed Early Adoption
Incentives program, manufacturers could generate credits in MYs 2024
through 2026 and use those credits in MYs 2027 and later.
We requested comment on all aspects of our proposed early adoption
incentive program. We were aware that some aspects of the proposed
requirements could be challenging to meet ahead of the required
compliance dates, and thus requested comment on any needed
flexibilities that we should include in the early adoption incentive
program in the final rule. See 87 FR 17555, March 28, 2022, for
additional discussion on the proposed Early Adoption Incentives
program, including specifics of our requests for comment.
Several commenters provided general comments on the proposed Early
Adoption Incentive program. Although many of the commenters generally
supported incentives such as emissions credit multipliers to encourage
early investments in emissions reductions technology, several were
concerned that the emissions credit multipliers would result in an
excess of credits that would undermine some of the benefits of the
rule; other commenters were concerned that the multipliers would
incentivize some technologies (e.g., hybrid powertrains, natural gas
engines) over others (e.g., battery-electric vehicles).
As described in preamble Section IV.G.7, the revised transitional
credit program that we are finalizing provides discounted credits for
engines that do not comply with all of the MY 2027 and later
requirements. In addition, after consideration of comments responding
to our request for comment about incentivizing early reductions through
our proposed transitional and Early Adoption Incentive program, the
final transitional credit program includes an additional pathway that
incentivizes manufacturers to produce engines that meet several of the
key final requirements for MY 2027 and later, including the LLC and
off-cycle standards for NOX, while meeting the current
useful life and warranty periods. We expect that this transitional
credit pathway will incentivize manufacturers to produce greater
volumes of the same or similar engines that they plan to produce to
comply with the MY 2024 Omnibus requirements. By choosing not to
finalize the Early Adoption Incentives program and instead finalizing a
modified version of the Transitional Credit program, we are avoiding
the potential concern some commenters raised that the credit
multipliers would result in a higher volume or magnitude of higher-
emitting MY 2027 and later engines compared to a program without
emission credit multipliers. We believe the Transitional Credit program
we are finalizing will better balance incentivizing emissions reduction
technologies prior to MY 2027 against avoiding an excess of emissions
credits that leads to much greater volumes or magnitudes of higher-
emitting engines in MYs 2027 and later. Moreover, by not finalizing the
Early Adoption Incentive program we are avoiding any concerns that the
emissions credit multipliers would incentivize some technologies over
others (see section 12.5 of the Response to Comments and preamble
Section IV.G.10 for additional discussion on battery-electric and fuel
cell electric vehicles in the final rule; see section 3 of the Response
to Comments for discussion on additional technology pathways).
9. Production Volume Allowance
After further consideration, including consideration of public
comments, EPA is finalizing an interim production volume allowance for
MYs 2027 through 2029 in 40 CFR 1036.150(k) that is consistent with our
request for comment in the proposal, but different in several key
aspects. In particular, the production volume allowance we are
finalizing allows manufacturers to use NOX emissions credits
to certify a limited volume of heavy heavy-duty engines compliant with
pre-MY 2027 requirements in MYs 2027 through 2029.\423\ In addition,
since we are requiring the use of credits to certify MY 2010 compliant
heavy heavy-duty engines in the early years of the final program, and
to aid in implementation, we are choosing to not limit the applications
that are eligible for this production volume allowance. Finally, the
production volume allowance in the final rule will be five percent of
the average U.S.-directed production volumes of Heavy HDE over three
model years, see 40 CFR 1036.801, and thus excludes engines certified
to different emission standards in CA or other states adopting the
Omnibus program. In this section, IV.G.9, we summarize our request for
comment on a production volume allowance, related stakeholder comments,
and EPA's responses to comments along with our rationale for the
production volume allowance in the final rule.
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\423\ Engines certified under this production volume allowance
would meet the current, pre-MY 2027 engine provisions of 40 CFR part
86, subpart A.
---------------------------------------------------------------------------
In the proposal we stated that we were considering a flexibility to
allow engine manufacturers, for model years 2027 through 2029 only, to
certify up to five percent of their total production volume of heavy-
duty highway CI engines in a given model year to the current, pre-MY
2027 engine provisions of 40 CFR part 86, subpart A. We stated the
allowance would be limited to Medium HDE or Heavy HDE engine families
that manufacturers show would be used in low volume, specialty
vocational vehicles. We noted that such an allowance from the MY 2027
criteria pollutant standards may be necessary to provide engine and
vehicle manufacturers additional lead time and flexibility to redesign
some low sales volume products to accommodate the technologies needed
to meet the proposed more stringent engine emission standards.
We requested comment on the potential option of a three-year
allowance from the proposed MY 2027 criteria pollutant standards for
engines installed in specialty vocational vehicles, including whether
and why the flexibility would be warranted and whether 5 percent of a
manufacturers engine production volume is an appropriate value for such
an interim provision. In addition, we requested comment on whether the
flexibility should be limited to specific vocational vehicle regulatory
subcategories and the engines used in them.
Several commenters provided perspectives on our request for comment
on providing an additional flexibility that would allow manufacturers
to certify up to five percent of their total production volume of 2027
through 2029 MY medium and heavy HDEs to the current Federal engine
provisions. Many environmental and state organizations opposed the
potential production volume allowance, while most manufacturers and one
supplier generally supported the potential allowance although they
suggested changes to the parameters included in the proposal.
Commenters opposing the production volume allowance had two primary
concerns. First, they stated that the production volume flexibility is
not needed because there is enough lead time between now and MY 2027 to
develop the technologies and overcome any packaging challenges. One
commenter further noted that the CARB
[[Page 4401]]
Omnibus standards would already be in effect in 15 percent of the
market. Second, commenters argued that the production volume allowance
would result in high NOX emissions and adverse health
effects, particularly in high-risk areas, which would undermine the
effectiveness of the rule to reduce emissions and protect public
health. One commenter noted that HHDEs last for many years before being
scrapped and that the production volume allowance, combined with other
flexibilities in the proposal, could result in significant emissions
impacts for many years to follow, which would create extreme difficulty
for California and other impacted states to achieve air quality goals.
Another commenter estimated that in MY 2027 through 2029, the
production volume allowance would result in 20,000 vehicles emitting
nearly 6 times more NOX on the FTP cycle than proposed
Option 1, and that these vehicles could represent 20-25 percent of the
total NOX emissions from MY 2027 through 2029 vehicles.
Still another commenter stated that the production volume allowance
would result in up to a 45 percent increase in NOX emissions
inventory for each applicable model year's production from a
manufacturer with products in a single useful life and power rating
category; the commenter noted that the emissions inventory impact could
be even greater if a manufacturer used the five percent allowance for
engines with longer useful life periods and higher power ratings. One
commenter opposing the production volume allowance stated that EPA
should not exempt any engines from complying with the adopted new
emission standards for any amount of time. Other commenters opposing
the production volume allowance stated that if EPA chose to finalize a
production allowance then emissions from those engines should be offset
with ABT emission credits to protect vulnerable impacted communities.
Finally, one commenter opposing the production volume allowance state
that if EPA chose to finalize the production allowance then the Agency
should provide strong technical justification for each engine category
subject to the provision.
Commenters generally supporting the production volume allowance
suggested several ways to further limit the flexibility, or suggested
additional flexibilities based on the CARB Omnibus program. For
instance, several engine manufacturers and their trade association
suggested limiting the provision to include only engines with low
annual miles traveled to minimize the emissions inventory impacts.
These commenters suggested limiting the allowance to engines with
greater than or equal to 525 hp or 510 hp in specific vehicle
applications, namely: Heavy-haul tractors and custom chassis motor
homes, concrete mixers, and emergency vehicles. Two engine
manufacturers further suggested the production volume allowance include
vehicles where aftertreatment is mounted off the frame rails, or that
EPA review and approve applications demonstrating severe packaging
constraints for low volume, highly specialized vocational applications.
Another engine manufacturer argued that manufacturers need to be able
to carry over some existing engines into MY 2027 and later for a few
years in order to adequately manage investments and prioritize ultra-
low NOX and ZEV technology adoption in the applications that
make the most sense. They further stated that EPA should consider
alternate credit program options that can be used to truly manage
investment and to prioritize appropriate applications by allowing
manufacturers to leverage credits to stage development programs. One
engine manufacturer and one supplier suggested EPA consider programs
similar to the CARB Omnibus' separate certification paths for `legacy
engines,' emergency vehicles, and low-volume high horsepower engines.
Additional details on comments received on the request for comment on a
potential production volume allowance are available in section 12.7 of
the Response to Comments.
After considering comments on the proposed production volume
allowance, we are finalizing an allowance in MY 2027 through 2029 for
manufacturers to certify up to five percent of their Heavy HDE U.S.-
directed production volume averaged over three model years (MY 2023
through 2025) as compliant with the standards and other requirements of
MY 2026 (i.e., the current, pre-MY 2027 engine provisions of 40 CFR
part 86, subpart A). As explained earlier in this Section IV.G, U.S.-
directed production volume excludes engines certified to different
state emission standards (e.g., would exclude engines certified to CARB
Omnibus standards if EPA grants the pending waiver request), and thus
would be a smaller total volume than all Heavy HDE engine production in
a given model year.424 425 By finalizing a production volume
allowance based on the average U.S.-directed production volume over
three model years (MY 2023 through 2025), rather than an allowance that
varies by production volume in each of the model years included in the
allowance period (MY 2027 through 2029), we are providing greater
certainty to manufacturers and other stakeholders regarding the number
of engines that could be produced under this allowance. Further, we
avoid the potential for economic conditions in any one year to unduly
influence the volume of engines that could be certified under this
allowance. Based on EPA certification data, we estimate that five
percent MY 2021 Heavy HDE would result in approximately 12,000 engines
per year permitted under this allowance.\426\
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\424\ See final part 1036, subpart H, and 40 CFR 1036.801.
\425\ EPA is reviewing a waiver request under CAA section 209(b)
from California for the Omnibus rule.
\426\ We note that there would be fewer engines eligible for
this allowance in the event we approve the pending waiver request
since our existing regulations provide that the production volume
allowance would exclude engines certified to state emission
standards that are different than the federal standards.
---------------------------------------------------------------------------
We are limiting the final production volume allowance to Heavy HDE,
rather than Heavy HDE and Medium HDE as proposed, because comments from
manufacturers generally pointed to Heavy HDE applications or otherwise
suggested limiting the allowance to larger engines (e.g., greater than
510 hp). After considering comments on the vehicle categories to
include in the production volume allowance, we are choosing not to
specify the vehicle categories for engines certified under this
production volume. Our rationale includes three main factors. First, we
are requiring manufacturers to use credits to certify engines under the
production volume allowance, which will inherently result in the
production of lower-emitting engines to generate the necessary credits.
We believe requiring emission credits to certify engines under the
production volume allowance better protects the expected emission
reductions from the final rule than limiting the production allowance
to specific vehicle categories. Our approach is consistent with some
commenters' recommendation to finalize a program that required the use
of emission credits to protect vulnerable impacted communities by
ensuring that lower-emitting engines are produced earlier to generate
the credits necessary to produce engines certified under this
allowance. Second, a variety of vehicle categories were identified in
comments as vehicle categories for which manufacturers may need
additional lead time and flexibility to redesign to accommodate the
technologies needed to meet the final emission standards. We expect
that the specific vehicle
[[Page 4402]]
category(ies) for which additional lead time and flexibility is of
interest will vary by manufacturer, and thus are choosing not to
specify vehicle categories to avoid competitive disruptions. Finally,
we are choosing not to limit the production volume allowance to
specific vehicle categories to simplify and streamline implementation;
the specific vehicle in which an engine will be installed is not always
known when an engine is produced, which would make implementing
restrictions on engines installed in specific vehicle categories
challenging for both EPA and manufacturers.
We continue to believe it is important to ensure that technology
turns over in a timely manner and that manufacturers do not continue
producing large numbers of higher-emitting pre-MY 2027 compliant
engines once the MY 2027 standards are in place. The combination of a
limited production volume (i.e., five percent of the average U.S.-
directed production volume over three model years, (MY 2023 through
2025, in MYs 2027 through 2029) and a requirement to use credits will
prevent the production of large numbers of these higher emitting
engines, while providing additional flexibility for manufacturers to
redesign engine product lines to accommodate the technologies needed to
meet the final emission standards.
For engines certified under the production volume allowance,
manufacturers would need to meet the standards and related requirements
that apply for model year 2026 engines under 40 CFR part 86, subpart A.
Engine families must be certified as separate engine families that
qualify for carryover certification, which means that the engine family
would still be properly represented by test data submitted in an
earlier model year.
Manufacturers would need to declare a NOX family
emission limit (FEL) that is at or below the standard specified in 40
CFR 86.007-11 and calculate negative credits by comparing the declared
NOX FEL to the FTP emission standard for model year 2027
engines. In addition, manufacturers would calculate negative credits
using a value for useful life of 650,000 miles to align with the credit
calculation for engines that will be generating credits under 40 CFR
part 1036 starting in model year 2027 (see Equation IV-I for credit
calculation). The inclusion of useful life and work produced over the
FTP in the calculation of credits addresses some commenters' concern
regarding the production of engines with higher power ratings and
longer useful life periods under the production volume allowance.
Manufacturers would need to demonstrate compliance with credit
accounting based on the same ABT reporting requirements that apply for
certified engines under 40 CFR part 1036.
See 40 CFR 1036.150(k) for additional details on the limited
production volume allowance in the final rule.
10. Zero Emission Vehicle NOX Emission Credits
After further consideration, including consideration of public
comments, EPA is not finalizing the proposed allowance for
manufacturers to generate NOX emissions credits from heavy-
duty zero emissions vehicles (ZEVs). Rather, the current 40 CFR 86.016-
1(d)(4), which specifies that heavy-duty ZEVs may not generate
NOX or PM emission credits, will continue to apply through
MY 2026, after which 40 CFR 1037.1 will apply. The final 40 CFR 1037.1
migrates without revisions the text of 40 CFR 86.016-1(d)(4), rather
than the revisions we proposed to allow manufacturers to generate
NOX emissions credits from ZEVs.427 428 In this
Section IV.G.10, we briefly describe the proposal to allow
manufacturers to generate NOX emissions credits from ZEVs;
the comments received on the proposal to allow ZEV NOX
credits; and EPA's response to those comments, which includes our
rationale for the approach to ZEV NOX credits in the final
rule.
---------------------------------------------------------------------------
\427\ At the time of proposal, we referred to battery-electric
vehicles (BEVs) and fuel cell electric vehicles (FCEVs); in this
final rule we generally use the term zero emissions vehicles (ZEVs)
to collectively refer to both BEVs and FCEVs.
\428\ As proposed, we are consolidating certification
requirements for BEVs and FCEVs over 14,000 pounds GVWR in 40 CFR
part 1037 such that manufacturers of BEVs and FCEVs over 14,000
pounds GVWR would certify to meeting the emission standards and
requirements of part 1037, as provided in the current 40 CFR 1037.1.
The final 1037.1 migrates without revisions the text of 40 CFR
86.016-1(d)(4), rather than the revisions we proposed to allow
manufacturers to generate NOX emissions credits from BEVs
and FCEVs. See preamble Section III for additional details on the
migration of 40 CFR 86.016-1(d)(4) to 40 CFR 1037.1.
---------------------------------------------------------------------------
We proposed that if manufacturers met certain requirements, then
they could generate NOX emissions credits from battery-
electric vehicles, BEVs, and fuel cell electric vehicles, FCEVs; we
refer to BEVs and FCEVs collectively as zero emissions vehicles,
ZEVs.\429\ Under the proposal, manufacturers would calculate the value
of NOX emission credits generated from ZEVs using the same
equation provided for engine emission credits (see Equation IV-1 in
final preamble Section IV.G.2). To generate the inputs to the equation,
we proposed that manufacturers would submit test data at the time of
certification, which is consistent with requirements for CI and SI
engine manufacturers to generate NOX emissions credits. We
proposed that vehicle manufacturers, rather than powertrain
manufacturers, would generate vehicle credits for ZEVs since vehicle
manufacturers already certify ZEVs to GHG standards under 40 CFR part
1037. To ensure that ZEV NOX credits were calculated
accurately, and reflected the environmental and public health benefits
of vehicles with zero tailpipe emissions over their full useful life,
we proposed that in MY 2024 and beyond, ZEVs used to generate
NOX emission credits would need to meet certain battery and
fuel cell performance requirements over the useful life period (i.e.,
durability requirements).
---------------------------------------------------------------------------
\429\ We also proposed to allow manufacturers to optionally test
the hybrid engine and powertrain together, rather than testing the
engine alone, to demonstrate the NOX emission performance
of hybrid electric vehicle (HEV) technologies; if the emissions
results of testing the hybrid engine and powertrain together showed
NOX emissions lower than the final standards, then
manufacturers could choose to participate in the NOX ABT
program; see preamble Section III.A for details on HEVs in the final
rule.
---------------------------------------------------------------------------
We requested comment on the general proposed approach of allowing
ZEVs to generate NOX credits, which could then be used in
the heavy-duty engine ABT program. We also requested comment on several
specific aspects of our proposal. See 87 FR 17558, March 28, 2022, for
additional discussion on the proposal to allow manufacturers to
generate NOX emissions credits from ZEVs if those vehicles
met the specified requirements.
Numerous commenters provided feedback on EPA's proposal to allow
manufacturers to generate NOX emissions credits from ZEVs.
The majority of commenters oppose allowing manufacturers to generate
NOX emissions credits from ZEVs. Several additional
commenters oppose ZEV NOX emissions credits unless there
were restrictions on the credits (e.g., shorter credit life, sunsetting
credit generation in 2026). Other commenters support allowing
manufacturers to generate NOX emissions credits from
electric vehicles. Arguments from each of these commenter groups are
summarized immediately below.
Commenters opposing NOX emissions credits for ZEVs
present several lines of argument, including the potential for: (1)
Substantial impacts on the emissions reductions expected from the
proposed rule, which could also result in disproportionate impacts in
disadvantaged communities already
[[Page 4403]]
overburdened with pollution; (2) a lack of improvements in conventional
engine technologies; and (3) ZEV NOX credits to result
higher emissions from internal combustion engines, rather than further
incentivizing additional ZEVs (further noting that other State and
Federal actions are providing more meaningful and less environmentally
costly HD ZEV incentives). Stakeholders opposing NOX
emissions credits from ZEVs were generally environmental or state
organizations, or suppliers of heavy-duty engine and vehicle
components.
In contrast, several commenters support allowing manufacturers to
generate these credits. Many of these commenters are heavy-duty engine
and vehicle manufacturers. Commenters supporting an allowance to
generate NOX emissions credits from ZEVs also provided
several lines of argument, including the potential for: (1) ZEVs to
help meet emissions reductions and air quality goals; (2) ZEV
NOX credits to be essential to the achievability of the
standards for some manufacturers; and (3) ZEV NOX credits to
allow manufacturers to manage investments across different products and
ultimately result in increased ZEV deployment. Each of these topic
areas is discussed further in section 12.5 of the Response to Comments
document.
Three considerations resulted in our decision not to finalize at
this time the allowance for manufacturers to generate NOX
emissions credits from heavy-duty ZEVs. First, the standards in the
final rule are technology-forcing, yet achievable for MY2027 and later
internal combustion engines without this flexibility. Second, since the
final standards are not based on projected utilization of ZEV
technology, and given that we believe there will be increased
penetration of ZEVs in the HD fleet by MY2027 and later, we are
concerned that allowing NOX emissions credits would result
in fewer emissions reductions than intended from this rule.\430\ For
example, by allowing manufacturers to generate ZEV NOX
credits, EPA would be allowing higher emissions (through engines using
credits to emit up to the FEL cap) in MY 2027 and later, without
requiring commensurate emissions reductions (through additional ZEVs
beyond those already entering the market without this rule), which
could be particularly impactful in communities already overburdened by
pollution. Third, we continue to believe that testing requirements to
ensure continued battery and fuel cell performance over the useful life
of a ZEV may be important to ensure the zero-emissions tailpipe
performance for which they are generating NOX credits;
however, after further consideration, including consideration of public
comments, we believe it is appropriate to take additional time to work
with industry and other stakeholders on any test procedures and other
specifications for ZEV battery and fuel cell performance over the
useful life period of the ZEV (see section 12.6 of the Response to
Comments document for additional detail on comments and EPA responses
to comments on the proposed ZEV testing and useful life and warranty
requirements).
---------------------------------------------------------------------------
\430\ For example, the recently passed Inflation Reduction Act
(IRA) has many incentives for promoting zero-emission vehicles, see
Sections 13403 (Qualified Clean Vehicles), 13404 (Alternative Fuel
Refueling Property Credit), 60101 (Clean Heavy-Duty Vehicles), 60102
(Grants to Reduce Air Pollution at Ports), and 70002 (United States
Postal Service Clean Fleets) of H.R. 5376.
---------------------------------------------------------------------------
In section 12.6 of the Response to Comments document, we further
discuss each of these considerations in our decision not to finalize
the allowance for manufacturers to generate NOX emissions
credits from ZEVs. Additional detail on comments received and EPA
responses to comments, including comments on more specific aspects of
comments on the proposed allowance for ZEV NOX emissions
credits, such as testing, useful life, and warranty requirements for
ZEVs, are also available in section 12.6 of the Response to Comments
document. Our responses to comments on the proposed vehicle
certification for ZEVs are summarized in preamble Section III, with
additional detail in section 12.6.3 of the Response to Comments
document.
V. Program Costs
In Chapter 3 of the RIA, we differentiate between direct, indirect,
and operating costs when estimating the costs of the rule. ``Direct''
costs represent the direct manufacturing costs of the technologies we
expect to be used to comply with the final standards over the final
useful lives; these costs accrue to the manufacturer. In this section
we use those costs to estimate the year-over-year manufacturing costs
going forward from the first year of implementation. ``Indirect''
costs, i.e., research and development (R&D), administrative costs,
marketing, and other costs of running a company, are associated with
the application of the expected technologies and also accrue to the
manufacturer. Like direct costs, indirect costs are expected to
increase under the final standards, in part due to the useful life
provisions. Indirect costs are also expected to increase under the
final program due to the warranty provisions. We term the sum of these
direct and indirect costs ``technology costs'' or ``technology package
costs.'' They represent the costs incurred by manufacturers--i.e.,
regulated entities--to comply with the final program.\431\
``Operating'' costs represent the costs of using the technology in the
field. Operating costs include, for example, changes in diesel exhaust
fluid (DEF) consumption or fuel consumption. These costs accrue to the
owner/operator of MY 2027 and later heavy-duty vehicles.\432\ We
present total costs associated with the final program in Section V.C.
All costs are presented in 2017 dollars consistent with the proposed
cost analysis, unless noted otherwise.
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\431\ More precisely, these technology costs represent costs
that manufacturers are expected to attempt to recapture via new
vehicle sales. As such, profits are included in the indirect cost
calculation. Clearly, profits are not a ``cost'' of compliance--EPA
is not imposing new regulations to force manufacturers to make a
profit. However, profits are necessary for manufacturers in the
heavy-duty industry, a competitive for-profit industry, to sustain
their operations. As such, manufacturers are expected to make a
profit on the compliant vehicles they sell, and we include those
profits in estimating technology costs.
\432\ Importantly, the final standards, useful lives, and
warranty periods apply only to new, MY 2027 and later heavy-duty
vehicles. The legacy fleet is not subject to the new requirements
and, therefore, users of prior model year vehicles will not incur
the operating costs we estimate.
---------------------------------------------------------------------------
We requested comment on all aspects of the cost analysis. In
particular, we requested comment on our estimation of warranty and
research and development costs via use of scalars applied to indirect
cost contributors (see Section V.A.2) and our estimates of emission
repair cost impacts (see Section V.B.3). We also requested that
comments include supporting data and/or alternative approaches that we
could have considered when developing estimates for the final
rulemaking.
In response to our requests, we received many helpful comments,
although lack of data in conjunction with some comments made it
challenging to evaluate the changes suggested by the commenter. After
careful consideration of the comments we received, we have made several
changes to the final cost analysis relative to the proposal. Those
changes are summarized in Table V-1. Note that, throughout this
discussion of costs, we use the term regulatory class which defines
vehicles with similar emission standards (see Chapter 5.2.2 of the
RIA); we use the term regulatory class for consistency with our MOVES
model and its classification system so that our costs align with our
inventory estimates
[[Page 4404]]
and the associated benefits discussed in Sections VI, VII and VIII.
Table V-1--Major Changes to the Cost Analysis Since Proposal
----------------------------------------------------------------------------------------------------------------
Area of change Proposed analysis Final analysis
----------------------------------------------------------------------------------------------------------------
Warranty costs......................... Warranty contributions to Warranty costs are calculated using a
indirect costs were scaled starting point of $1,000 (2018
using the ratio of proposed dollars, $976 in 2017 dollars) per
provisions (miles/age) to the year of warranty coverage for a
baseline provisions. vehicle equipped with a heavy HDE;
warranty costs for other regulatory
classes were scaled by the ratio of
the direct manufacturing costs (DMC)
for the regulatory class to the DMC
of the heavy HDE regulatory class.
Warranty costs......................... Baseline warranty costs were Baseline warranty costs are estimated
estimated for the regulated assuming that a percentage of
warranty period only (i.e., the vehicles are purchased with extended
analysis assumed that no warranties.
vehicles were purchased with
extended warranties).
Emission repair costs.................. Repair costs used a cost per Repair costs use a 2021 study by the
mile curve derived from a Fleet American Transportation Research
Advantage Whitepaper with Institute (ATRI) in place of the
direct manufacturing cost (DMC) Fleet Advantage Whitepaper.
ratio scalars applied to
determine cost per mile values
for different regulatory
classes.
Fuel prices............................ Used AEO2018 fuel prices in 2017 Uses AEO2019 fuel prices for
dollars. consistency with the final rule
version of the MOVES model while
continuing with 2017 dollars.
Technology piece costs................. Exhaust aftertreatment system EAS costs have been updated and are
(EAS) costs were based on an based on FEV teardowns as described
ICCT methodology with updates in RIA Chapter 3.
by EPA.
----------------------------------------------------------------------------------------------------------------
A. Technology Package Costs
Commenters' primary comment with respect to our proposed technology
package costs dealt with the need to replace the emission control
system due to the combination of the low NOX standards with
the long warranty and useful life provisions under proposed Option 1.
Another comment with respect to our proposed technology package costs
dealt with the estimated warranty costs, including both the methodology
used and the magnitude of the cost estimated by EPA. As explained in
Sections III and IV, the final program neither imposes numeric
NOX standards as stringent as, nor does the final rule for
heavy HDE contain warranty and useful life provisions as long as,
proposed Option 1. We address these comments in more detail in section
18 of the RTC. EPA considers the concerns raised in first of these
comments to be obviated by the final emission standards and regulatory
useful life values, in light of which we foresee no need for a routine
replacement of the entire emission control system to maintain in-use
compliance as suggested by some commenters. Regarding the second, as
discussed in more detail in Section V.A.2 and section 18 of the RTC,
EPA has updated the warranty cost methodology, including based on
information submitted by commenters, and this has resulted in different
costs associated with warranty.
Individual technology piece costs are presented in Chapter 3 of the
RIA. The direct manufacturing costs (DMC) presented in RIA Chapter 3
use a different dollar basis than the cost analysis, and as such, the
DMC values presented here have been adjusted to 2017 dollars. Following
the first year of implementation, the costs also account for a learning
effect to represent the cost reductions expected to occur via the
``learning by doing'' phenomenon.\433\ This provides a year-over-year
cost for each technology package--where a technology package consists
of the entire emission-control system--as it is applied to new engine
sales. We then apply industry standard ``retail price equivalent''
(RPE) markup factors, with adjustments discussed in the rest of this
section, to estimate indirect costs associated with each technology
package. Both the learning effects applied to direct costs and the
application of markup factors to estimate indirect costs are consistent
with the cost estimation approaches used in EPA's past transportation-
related regulatory programs. The sum of the direct and indirect costs
represents our estimate of technology costs per vehicle on a year-over-
year basis. These technology costs multiplied by estimated sales then
represent the total technology costs associated with the final program.
---------------------------------------------------------------------------
\433\ The ``learning by doing'' phenomenon is the process by
which the cost to manufacture a good decreases as more of that good
is produced, as producers of the good learn from their experience.
---------------------------------------------------------------------------
This cost calculation approach presumes that the expected
technologies will be purchased by original equipment manufacturers
(OEMs) from their suppliers. So, while the DMC estimates include the
indirect costs and profits incurred by the supplier, the indirect cost
markups we apply cover the indirect costs incurred by OEMs to
incorporate the new technologies into their vehicles and to cover
profit margins typical of the heavy-duty truck industry. We discuss the
indirect costs in more detail in Section V.A.2.
1. Direct Manufacturing Costs
To produce a unit of output, manufacturers incur direct and
indirect costs. Direct costs include cost of materials and labor costs
to manufacture that unit. Indirect costs are discussed in the following
section. The direct manufacturing costs presented here include
individual technology costs for emission-related engine components and
exhaust aftertreatment systems (EAS).
Notably, for this analysis we include not only the marginal
increased costs associated with the standards, but also the emission
control system costs for the baseline, or no action, case.\434\
Throughout this discussion, we refer to baseline case costs, or
baseline costs, which reflect our cost estimate of emission-related
engine systems and the exhaust aftertreatment system absent impacts of
this final rule. This inclusion of baseline system costs contrasts with
EPA's approach in recent greenhouse gas rules or the light-duty Tier 3
criteria pollutant rule where we estimated costs relative to a baseline
case, which obviated the need to estimate baseline costs. We have
included baseline costs in this analysis because the new emissions
warranty and regulatory useful life provisions are expected to have
some impact on not only the new technology added to comply with the
final standards, but also on emission control technologies already
developed and in use. The new warranty and useful life provisions will
increase costs not only for the new technology added in response to the
new standards, but also for the technology already in place
[[Page 4405]]
(to which the new technology is added) because the new warranty and
useful life provisions will apply to the entire emission-control
system, not just the new technology added in response to the new
standards. The baseline direct manufacturing costs detailed in this
section are intended to reflect that portion of baseline case engine
hardware and aftertreatment systems for which new indirect costs will
be incurred due to the new warranty and useful life provisions, even
apart from changes in the level of emission standards.
---------------------------------------------------------------------------
\434\ For this cost analysis, the baseline, or no action, case
consists of MY 2019 engines and emission control systems. See also
Section VI for more information about the emission inventory
baseline and how that baseline is characterized.
---------------------------------------------------------------------------
As done in the NPRM, we have estimated the baseline engine costs
based on studies done by the International Council on Clean
Transportation (ICCT), as discussed in more detail in Chapter 7 of the
RIA. As discussed there, the baseline engine costs consist of
turbocharging, fuel system, exhaust gas recirculation, etc. These costs
represent those for technologies that will be subject to new, longer
warranty and useful life provisions under this final rule. For costs
associated with the action case, we have used FEV-conducted teardown-
based costs as presented in Chapter 3 of the RIA for newly added
cylinder deactivation systems,\435\ and for the exhaust aftertreatment
system (EAS) costs.\436\ The direct manufacturing costs for the
baseline engine+aftertreatment and for the final program are shown for
diesel engines in Table V-2, gasoline engines in Table V-3 and CNG
engines in Table V-4. Costs are shown for regulatory classes included
in the cost analysis and follow the categorization approach used in our
MOVES model. Please refer to Chapter 6 of the RIA for a description of
the regulatory classes and why the tables that follow include or do not
include each regulatory class. In short, where MOVES has regulatory
class populations and associated emission inventories, our cost
analysis estimates costs. Note also that, throughout this section, we
use several acronyms, including heavy-duty engine (HDE), exhaust gas
recirculation (EGR), exhaust aftertreatment system (EAS), and
compressed natural gas (CNG).
---------------------------------------------------------------------------
\435\ Mamidanna, S. 2021. Heavy-Duty Engine Valvetrain
Technology Cost Assessment. U.S. EPA Contract with FEV North
America, Inc., Contract No. 68HERC19D0008, Task Order No.
68HERH20F0041.Submitted to the Docket with the proposal.
\436\ Mamidanna, S. 2021. Heavy-Duty Vehicles Aftertreatment
Systems Cost Assessment. Submitted to the Docket with the proposal.
Table V-2--Diesel Technology and Package Direct Manufacturing Costs per Engine by Regulatory Class for the
Baseline and Final Program, MY2027, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
Final program
MOVES regulatory class Technology Baseline (MY2027 increment
to baseline)
----------------------------------------------------------------------------------------------------------------
Light HDE.................................... Package........................ 3,699 1,957
Engine hardware................ 1,097 0
Closed crankcase............... 18 37
Cylinder deactivation.......... 0 196
EAS............................ 2,585 1,724
Medium HDE................................... Package........................ 3,808 1,817
Engine hardware................ 1,254 0
Closed crankcase............... 18 37
Cylinder deactivation.......... 0 147
EAS............................ 2,536 1,634
Heavy HDE.................................... Package........................ 5,816 2,316
Engine hardware................ 2,037 0
Closed crankcase............... 18 37
Cylinder deactivation.......... 0 206
EAS............................ 3,761 2,074
Urban bus.................................... Package........................ 3,884 1,850
Engine hardware................ 1,254 0
Closed crankcase............... 18 37
Cylinder deactivation.......... 0 147
EAS............................ 2,613 1,666
----------------------------------------------------------------------------------------------------------------
Table V-3--Gasoline Technology and Package Direct Manufacturing Costs per Engine by Regulatory Class for the
Baseline and Final Program, MY2027, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
Final program
MOVES regulatory class Technology Baseline (MY2027 increment
to baseline)
----------------------------------------------------------------------------------------------------------------
Light HDE.................................... Package........................ 2,681 688
Engine hardware................ 522 0
Aftertreatment................. 2,158 664
ORVR........................... 0 24
Medium HDE................................... Package........................ 2,681 688
Engine hardware................ 522 0
Aftertreatment................. 2,158 664
ORVR........................... 0 24
Heavy HDE.................................... Package........................ 2,681 688
Engine hardware................ 522 0
Aftertreatment................. 2,158 664
ORVR........................... 0 24
----------------------------------------------------------------------------------------------------------------
[[Page 4406]]
Table V-4--CNG Technology and Package Direct Manufacturing Costs per Engine by Regulatory Class, for the
Baseline and Final Program, MY2027, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
Final standards
MOVES regulatory class Technology Baseline (MY2027 increment
to baseline)
----------------------------------------------------------------------------------------------------------------
Heavy HDE.................................... Package........................ 8,585 25
Engine hardware................ 896 0
Aftertreatment................. 7,689 25
Urban bus.................................... Package........................ 6,438 19
Engine hardware................ 672 0
Aftertreatment................. 5,766 19
----------------------------------------------------------------------------------------------------------------
The direct costs are then adjusted to account for learning effects
going forward from the first year of implementation. We describe in
detail in Chapter 7 of the RIA the approach used to apply learning
effects in this analysis. Learning effects were applied on a technology
package cost basis, and MOVES-projected sales volumes were used to
determine first-year sales and cumulative sales. The resultant direct
manufacturing costs and how those costs decrease over time are
presented in Section V.A.3.
2. Indirect Costs
The indirect costs presented here are all the costs estimated to be
incurred by manufacturers of new heavy-duty engines and vehicles
associated with producing the unit of output that are not direct costs.
For example, they may be related to production (such as research and
development (R&D)), corporate operations (such as salaries, pensions,
and health care costs for corporate staff), or selling (such as
transportation, dealer support, and marketing). Indirect costs are
generally recovered by allocating a share of the indirect costs to each
unit of good sold. Although direct costs can be allocated to each unit
of good sold, it is more challenging to account for indirect costs
allocated to a unit of goods sold. To ensure that regulatory analyses
capture the changes in indirect costs, markup factors (which relate
total indirect costs to total direct costs) have been developed and
used by EPA and other stakeholders. These factors are often referred to
as retail price equivalent (RPE) multipliers. RPE multipliers provide,
at an aggregate level, the relative shares of revenues, where:
Revenue = Direct Costs + Indirect Costs
Revenue/Direct Costs = 1 + Indirect Costs/Direct Costs = Retail Price
Equivalent (RPE)
Resulting in:
Indirect Costs = Direct Costs x (RPE-1)
If the relationship between revenues and direct costs (i.e., RPE)
can be shown to equal an average value over time, then an estimate of
direct costs can be multiplied by that average value to estimate
revenues, or total costs. Further, that difference between estimated
revenues, or total costs, and estimated direct costs can be taken as
the indirect costs. EPA has frequently used these multipliers \437\ to
predict the resultant impact on costs associated with manufacturers'
responses to regulatory requirements and we are using that approach in
this analysis to account for most of the indirect cost contributions.
The exception is the warranty cost as described in this section.
---------------------------------------------------------------------------
\437\ See 75 FR 25324, 76 FR 57106, 77 FR 62624, 79 FR 23414, 81
FR 73478, 86 FR 74434.
---------------------------------------------------------------------------
The cost analysis estimates indirect costs by applying the RPE
markup factor used in past rulemakings (such as those setting
greenhouse gas standards for heavy-duty trucks).\438\ The markup
factors are based on financial filings with the Securities and Exchange
Commission for several engine and engine/truck manufacturers in the
heavy-duty industry.\439\ The RPE factors for the HD truck industry are
shown in Table V-5. Also shown in Table V-5 are the RPE factors for
light-duty vehicle manufacturers.\440\
---------------------------------------------------------------------------
\438\ 76 FR 57106; 81 FR 73478.
\439\ Heavy Duty Truck Retail Price Equivalent and Indirect Cost
Multipliers, Draft Report, July 2010.
\440\ Rogozhin, A., et al., Using indirect cost multipliers to
estimate the total cost of adding new technology in the automobile
industry. International Journal of Production Economics (2009),
doi:10.1016/j.ijpe.2009.11.031.
Table V-5--Retail Price Equivalent Factors in the Heavy-Duty and Light-
Duty Industries
------------------------------------------------------------------------
HD truck LD vehicle
Cost contributor industry industry
------------------------------------------------------------------------
Direct manufacturing cost............... 1.00 1.00
Warranty................................ 0.03 0.03
R&D..................................... 0.05 0.05
Other (admin, retirement, health, etc.). 0.29 0.36
Profit (cost of capital)................ 0.05 0.06
RPE..................................... 1.42 1.50
------------------------------------------------------------------------
For this analysis, EPA based indirect cost estimates for diesel and
CNG regulatory classes on the HD Truck Industry RPE values shown in
Table V-5.\441\ For gasoline regulatory classes, we used the LD Vehicle
Industry values shown in Table V-5 since they more closely represent
the cost structure of manufacturers in that industry--Ford, General
Motors, and Stellantis.
---------------------------------------------------------------------------
\441\ Note that the report used the term ``HD Truck'' while EPA
generally uses the term ``HD vehicle;'' they are equivalent when
referring to this report.
---------------------------------------------------------------------------
Of the cost contributors listed in Table V-5, Warranty and R&D are
the elements of indirect costs that the final rule requirements are
expected to impact. As discussed in Section IV of this preamble, EPA is
lengthening the required warranty period, which we expect to increase
the contribution of warranty costs to indirect costs. EPA is also
tightening the numeric standards and extending the regulatory useful
life,
[[Page 4407]]
which we expect to result in increased R&D expenses as compliant
systems are developed. All other indirect cost elements--those
encapsulated by the ``Other'' category, including General and
Administrative Costs, Retirement Costs, Healthcare Costs, and other
overhead costs--as well as Profits, are expected to scale according to
their historical levels of contribution.
As mentioned, Warranty and R&D are the elements of indirect costs
that are expected to be impacted. Warranty expenses are the costs that
a business expects to or has already incurred for the repair or
replacement of goods that it has sold. The total amount of warranty
expense is limited by the warranty period that a business typically
allows. After the warranty period for a product has expired, a business
no longer incurs a warranty liability; thus, a longer warranty period
results in a longer period of liability for a product. At the time of
sale, a warranty liability account is adjusted to reflect the expected
costs of any potential future warranty claims. If and when warranty
claims are made by customers, the warranty liability account is debited
and a warranty claims account is credited to cover warranty claim
expenses.\442\
---------------------------------------------------------------------------
\442\ Warranty expense is recognized in the same period as the
sales for the products that were sold, if it is probable that an
expense will be incurred and the company can estimate the amount of
the expense. For more discussion of this topic, see the supporting
material in this docket, AccountingTools.com, December 24, 2020,
accessed January 28, 2021.
---------------------------------------------------------------------------
In the proposed analysis, to address the expected increased
indirect cost contributions associated with warranty (increased funding
of the warranty liability account) due to the proposed longer warranty
requirements, we applied scaling factors commensurate with the changes
in proposed Option 1 or Option 2 to the number of miles included in the
warranty period (i.e., VMT-based scaling factors). Industry commenters
took exception to this approach, arguing that it resulted in
underestimated costs associated with warranty. To support their
comments, one commenter submitted data that showed costs associated
with actual warranty claims for roughly 250,000 heavy heavy-duty
vehicles. The following figure includes the chart from their comments,
which are also in the public docket for this rule.
[GRAPHIC] [TIFF OMITTED] TR24JA23.002
Figure V-1 Warranty Costs Submitted as Part of the Comments From An
Industry Association; See EPA-HQ-OAR-2019-0055-1203-A1, Page 151
EPA considers this comment and supporting information to be
persuasive, not only because it represents data, but also because it
represents data from three manufacturers and over 250,000 vehicles;
thus, we switched from a VMT-based scaling approach to a years-based
approach to better take into account this information. However, the
data are for heavy HDE, so it is not possible to determine an
appropriate cost per year for light or medium HDE from the data
directly. Also, the data represent actual warranty claims without any
mention of the warranty claims rate (i.e., the share of engines sold
that are making the warranty claims represented in the data). This
latter issue makes it difficult to determine the costs that might be
imposed on all new engines sold to cover the future warranty claims for
the relatively smaller fraction of engines that incur warranty repair.
In other words, if all heavy HDE purchases are helping to fund a
warranty liability account, it is unclear if the $1,000 per year per
engine is the right amount or if $1,000 per year is needed on only that
percent of engines that will incur warranty repair. In the end,
warranty costs imposed on new engine sales should be largely recouped
by purchasers of those engines in the form of reduced emission repair
expenses. EPA believes it is unlikely that a manufacturer would use
their warranty program as a profit generator under the $1,000 per
engine approach, especially in a market as competitive as the HD engine
and vehicle industry. The possibility exists that the costs associated
with the longer warranty
[[Page 4408]]
coverage required by this rule will (1) converge towards those of the
better performing OEMs; and (2) drop over time via something analogous
to the learning by doing phenomenon described earlier. If true, we have
probably overestimated the costs estimated here as attributable to this
rule.
Thus, after careful consideration of these comments regarding
warranty, and the engineering judgement of EPA subject matter experts,
we revised our approach to estimating warranty costs, and for the final
rule we have estimated warranty costs assuming a cost of $1,000 (2018
dollars or $977 in 2017 dollars) per estimated number of years of
warranty coverage for a heavy heavy-duty diesel engine or heavy-duty
vehicle equipped with such an engine. For other regulatory (engine)
classes, we have scaled that value by the ratio of their estimated
baseline emission-control system direct cost to the estimated emission-
control system direct cost of the baseline heavy heavy-duty diesel
engine. We use the baseline heavy heavy-duty diesel engine direct cost
here because it should be consistent with the data behind the $1,000
per year value. The resulting emission-related warranty costs per year
for a MY 2027 HD engine are as shown in Table V-6.
Table V-6--Warranty Costs per Year
[2017 Dollars] \a\
----------------------------------------------------------------------------------------------------------------
MOVES regulatory class Scaling approach Diesel Gasoline CNG
----------------------------------------------------------------------------------------------------------------
Light HDE............................... Base Light HDE DMC/Base Diesel 621 450 ...........
Heavy HDE DMC.
Medium HDE.............................. Base Medium HDE DMC/Base Diesel 639 449 ...........
Heavy HDE DMC.
Heavy HDE............................... Base Heavy HDE DMC/Base Diesel 977 448 1,442
Heavy HDE DMC.
Urban bus............................... Base Urban bus DMC/Base Diesel 652 ........... 1,081
Heavy HDE DMC.
----------------------------------------------------------------------------------------------------------------
\a\ The Base Diesel HDE DMC would be the $5,816 value shown in Table V-2.
As noted, we have used the estimated number of years of warranty
coverage, not the regulated number of years. In other words, a long-
haul tractor accumulating over 100,000 miles per year will reach any
regulated warranty mileage prior to a refuse truck accumulating under
40,000 miles per year, assuming both are in the same regulatory class
and, therefore, have the same warranty provisions. In all cases, we
estimate the number of years of warranty coverage by determining the
minimum number of years to reach either the number of years, the number
of miles, or the number of hours of operation covered by the EPA
emissions-related warranty. We provide more detail on this in Chapter 7
of the final RIA.
Lastly, with respect to warranty, we have estimated that many of
the regulated products are sold today with a warranty period longer
than the EPA required emissions-related warranty period. In the
proposal, we calculated baseline warranty costs only for the required
warranty periods. In the final analysis, we calculate baseline warranty
costs based on the warranty periods for which engines are actually
sold. For diesel and CNG heavy HDE, we assume all are sold with
warranties covering 250,000 miles, and for diesel and CNG medium HDE,
we assume half are sold with warranties covering 150,000 miles. For all
other engines and associated fuel types, we have not estimated any use
of extended warranties in the baseline.
We use these annual warranty costs for both the baseline and the
final standards despite the addition of new technology associated with
this final rule. We believe this is reasonable for two reasons: (1) The
source data included several years of data during which there must have
been new technology introductions, yet annual costs appear to have
remained generally steady; and, (2) the R&D we expect to be done,
discussed next, is expected to improve overall durability, which should
serve to help maintain historical annual costs.
For R&D, we have maintained the approach used in the proposal,
although it is applied using the final useful life provisions. For
example, for R&D on a Class 8 truck, the final standards would extend
regulatory useful life from 10 years, 22,000 hours, or 435,000 miles,
to 11 years, 32,000 hours, or 650,000 miles. We have applied a scaling
factor of 1.49 (650/435) to the 0.05 R&D contribution factor for MYs
2027 and later. We apply this same methodology to estimating R&D for
other vehicle categories. We estimate that once the development efforts
into longer useful life are complete, increased expenditures will
return to their normal levels of contribution. Therefore, we have
implemented R&D scalars for three years (2027 through 2029). In MY 2030
and later, the R&D scaling factors are no longer applied.
The VMT-based scaling factors applied to R&D cost contributors used
in our cost analysis of final standards are shown in Table V-7 for
diesel and CNG regulatory classes and in Table V-8 for gasoline
regulatory classes.
Table V-7--Scaling Factors Applied to RPE Contribution Factors To Reflect Changes in Their Contributions, Diesel
& CNG Regulatory Classes
----------------------------------------------------------------------------------------------------------------
R&D scalars
Scenario MOVES regulatory class ----------------------------
MY2027-2029 MY2030+
----------------------------------------------------------------------------------------------------------------
Baseline....................................... Light HDE......................... 1.00 1.00
Medium HDE........................ 1.00 1.00
Heavy HDE......................... 1.00 1.00
Urban Bus......................... 1.00 1.00
Final Program.................................. Light HDE......................... 2.45 1.00
Medium HDE........................ 1.89 1.00
Heavy HDE......................... 1.49 1.00
Urban Bus......................... 1.49 1.00
----------------------------------------------------------------------------------------------------------------
[[Page 4409]]
Table V-8--Scaling Factors Applied to RPE Contribution Factors To Reflect Changes in Their Contributions,
Gasoline Regulatory Classes
----------------------------------------------------------------------------------------------------------------
R&D scalars
Scenario MOVES regulatory class ----------------------------
MY2027-2029 MY2030+
----------------------------------------------------------------------------------------------------------------
Baseline....................................... Light HDE......................... 1.00 1.00
Medium HDE........................ 1.00 1.00
Heavy HDE......................... 1.00 1.00
Final Program.................................. Light HDE......................... 1.82 1.00
Medium HDE........................ 1.82 1.00
Heavy HDE......................... 1.82 1.00
----------------------------------------------------------------------------------------------------------------
Lastly, as mentioned in Section V.A.1, the markups for estimating
indirect costs are applied to our estimates of the absolute direct
manufacturing costs for emission-control technology shown in Table V-2,
Table V-3 and Table V-4, not just the incremental costs associated with
the final program (i.e., the Baseline + Final costs). Table V-9
provides an illustrative example using a baseline technology cost of
$5000, a final incremental cost of $1000, and an indirect cost R&D
contribution of 0.05 with a simple scalar of 1.5 associated with a
longer useful life period. In this case, the costs could be calculated
according to two approaches, as shown in Table V-9. By including the
baseline costs, we are estimating new R&D costs in the final standards,
as illustrated by the example where including baseline costs results in
R&D costs of $450 while excluding baseline costs results in R&D costs
of $75.
Table V-9--Simplified Hypothetical Example of Indirect R&D Costs
Calculated on An Incremental vs. Absolute Technology Package Cost
[Values are not from the analysis and are for presentation only]
------------------------------------------------------------------------
Using incremental
costs only Using absolute costs
------------------------------------------------------------------------
Baseline direct $5,000.............. $5,000.
manufacturing cost (DMC).
Direct Manufacturing Cost $1,000.............. $5,000 + $1,000 =
(DMC). $6,000.
Indirect R&D Costs.......... $1,000 x 0.05 x 1.5 $6,000 x 0.05 x 1.5
= $75. = $450.
Incremental DMC + R&D....... $1,000 + $75 = $6,000 + $450-$5,000
$1,075. = $1,450.
------------------------------------------------------------------------
3. Technology Costs per Vehicle
The following tables present the technology costs estimated for the
final program on a per-vehicle basis for MY 2027. Reflected in these
tables are learning effects on direct manufacturing costs and scaling
effects associated with final program requirements. The sum is also
shown and reflects the direct plus indirect cost per vehicle in the
specific model year. Note that the indirect costs shown include
warranty, R&D, ``other,'' and profit, the latter two which scale with
direct costs via the indirect cost contribution factor. While direct
costs do not change across the different vehicle types (i.e., long-haul
versus short-haul combination), the indirect costs do vary because
differing miles driven and operating hours between types of vehicles
result in different warranty and useful life estimates in actual use.
These differences impact the estimated warranty and R&D costs.
We show costs per vehicle here, but it is important to note that
these are costs and not prices. We are not estimating how manufacturers
might price their products. Manufacturers may pass costs along to
purchasers via price increases in a manner consistent with what we show
here. However, manufacturers may also price certain products higher
than what we show while pricing others lower--the higher-priced
products thereby subsidizing the lower-priced products. This is true in
any market, not just the heavy-duty highway industry. This may be
especially true with respect to the indirect costs we have estimated
because, for example, R&D done to improve emission durability can
readily transfer across different engines whereas hardware added to an
engine is uniquely tied to that engine.
Importantly, we present costs here for MY2027 vehicles, but these
costs continue for every model year going forward from there.
Consistent with the learning impacts described in section V.A.2, the
costs per vehicle decrease slightly over time, but only the increased
R&D costs are expected to decrease significantly. Increased R&D is
estimated to occur for three years following and including MY2027
(i.e., MY2027-29), after which time its contribution to indirect costs
returns to lower values as shown in Table V.4.
Table V-10--MY2027 Diesel Light HDE Technology Costs per Vehicle Associated With the Final Program, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
Direct costs Indirect costs Costs per vehicle
----------------------------------------------------------------------------------------------------------------
FRM Baseline
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............................. 3,699 2,332 6,031
Other Buses.............................................. 3,699 2,263 5,962
School Buses............................................. 3,699 3,829 7,528
Short-Haul Single Unit Trucks............................ 3,699 2,851 6,550
Transit Buses............................................ 3,699 2,263 5,962
----------------------------------------------------------------------------------------------------------------
[[Page 4410]]
FRM Baseline + Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............................. 5,656 6,353 12,009
Other Buses.............................................. 5,656 6,064 11,720
School Buses............................................. 5,656 8,830 14,485
Short-Haul Single Unit Trucks............................ 5,656 8,530 14,186
Transit Buses............................................ 5,656 6,064 11,720
----------------------------------------------------------------------------------------------------------------
Increased Cost of the Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............................. 1,957 4,021 5,978
Other Buses.............................................. 1,957 3,800 5,757
School Buses............................................. 1,957 5,001 6,957
Short-Haul Single Unit Trucks............................ 1,957 5,680 7,636
Transit Buses............................................ 1,957 3,800 5,757
----------------------------------------------------------------------------------------------------------------
Table V-11--MY2027 Diesel Medium HDE Technology Costs per Vehicle Associated With the Final Program, 2017
Dollars
----------------------------------------------------------------------------------------------------------------
Direct costs Indirect costs Costs per vehicle
----------------------------------------------------------------------------------------------------------------
FRM Baseline
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............................. 3,808 3,774 7,582
Motor Homes.............................................. 3,808 4,682 8,490
Other Buses.............................................. 3,808 3,597 7,404
Refuse Trucks............................................ 3,808 4,217 8,025
School Buses............................................. 3,808 4,682 8,490
Short-Haul Combination Trucks............................ 3,808 2,595 6,402
Short-Haul Single Unit Trucks............................ 3,808 4,682 8,490
Transit Buses............................................ 3,808 3,597 7,404
----------------------------------------------------------------------------------------------------------------
FRM Baseline + Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............................. 5,625 7,572 13,197
Motor Homes.............................................. 5,625 8,839 14,464
Other Buses.............................................. 5,625 7,175 12,799
Refuse Trucks............................................ 5,625 8,564 14,189
School Buses............................................. 5,625 8,839 14,464
Short-Haul Combination Trucks............................ 5,625 4,930 10,555
Short-Haul Single Unit Trucks............................ 5,625 8,839 14,464
Transit Buses............................................ 5,625 7,175 12,799
----------------------------------------------------------------------------------------------------------------
Increased Cost of the Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............................. 1,817 3,798 5,615
Motor Homes.............................................. 1,817 4,157 5,974
Other Buses.............................................. 1,817 3,578 5,395
Refuse Trucks............................................ 1,817 4,347 6,164
School Buses............................................. 1,817 4,157 5,974
Short-Haul Combination Trucks............................ 1,817 2,335 4,153
Short-Haul Single Unit Trucks............................ 1,817 4,157 5,974
Transit Buses............................................ 1,817 3,578 5,395
----------------------------------------------------------------------------------------------------------------
Table V-12--MY2027 Diesel Heavy HDE Technology Costs per Vehicle Associated With the Final Program, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
Direct costs Indirect costs Costs per vehicle
----------------------------------------------------------------------------------------------------------------
FRM Baseline
----------------------------------------------------------------------------------------------------------------
Long-Haul Combination Trucks............................. 5,816 4,025 9,841
Long-Haul Single Unit Trucks............................. 5,816 7,151 12,967
Motor Homes.............................................. 5,816 7,151 12,967
Other Buses.............................................. 5,816 7,151 12,967
Refuse Trucks............................................ 5,816 7,151 12,967
School Buses............................................. 5,816 7,151 12,967
Short-Haul Combination Trucks............................ 5,816 5,658 11,473
[[Page 4411]]
Short-Haul Single Unit Trucks............................ 5,816 7,151 12,967
----------------------------------------------------------------------------------------------------------------
FRM Baseline + Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Combination Trucks............................. 8,132 6,535 14,667
Long-Haul Single Unit Trucks............................. 8,132 13,139 21,271
Motor Homes.............................................. 8,132 13,139 21,271
Other Buses.............................................. 8,132 13,139 21,271
Refuse Trucks............................................ 8,132 13,139 21,271
School Buses............................................. 8,132 13,139 21,271
Short-Haul Combination Trucks............................ 8,132 9,474 17,606
Short-Haul Single Unit Trucks............................ 8,132 13,139 21,271
----------------------------------------------------------------------------------------------------------------
Increased Cost of the Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Combination Trucks............................. 2,316 2,510 4,827
Long-Haul Single Unit Trucks............................. 2,316 5,988 8,304
Motor Homes.............................................. 2,316 5,988 8,304
Other Buses.............................................. 2,316 5,988 8,304
Refuse Trucks............................................ 2,316 5,988 8,304
School Buses............................................. 2,316 5,988 8,304
Short-Haul Combination Trucks............................ 2,316 3,816 6,132
Short-Haul Single Unit Trucks............................ 2,316 5,988 8,304
----------------------------------------------------------------------------------------------------------------
Table V-13--MY2027 Diesel Urban Bus Technology Costs per Vehicle Associated With the Final Program, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
Direct costs Indirect costs Costs per vehicle
----------------------------------------------------------------------------------------------------------------
FRM Baseline............................................. 3,884 3,238 7,122
FRM Baseline + Final Program............................. 5,734 8,901 14,635
Increased Cost of the Final Program...................... 1,850 5,663 7,512
----------------------------------------------------------------------------------------------------------------
Table V-14--MY2027 Gasoline HDE Technology Costs per Vehicle Associated With the Final Program, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
Direct costs Indirect costs Costs per vehicle
----------------------------------------------------------------------------------------------------------------
FRM Baseline
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............................. 2,681 1,905 4,585
Motor Homes.............................................. 2,681 3,511 6,192
Other Buses.............................................. 2,681 1,855 4,535
School Buses............................................. 2,681 2,989 5,670
Short-Haul Single Unit Trucks............................ 2,681 2,280 4,961
Transit Buses............................................ 2,681 1,855 4,535
----------------------------------------------------------------------------------------------------------------
FRM Baseline + Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............................. 3,369 3,784 7,153
Motor Homes.............................................. 3,369 6,223 9,592
Other Buses.............................................. 3,369 3,624 6,993
School Buses............................................. 3,369 6,223 9,592
Short-Haul Single Unit Trucks............................ 3,369 4,986 8,355
Transit Buses............................................ 3,369 3,624 6,993
----------------------------------------------------------------------------------------------------------------
Increased Cost of the Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............................. 688 1,880 2,568
Motor Homes.............................................. 688 2,712 3,401
Other Buses.............................................. 688 1,770 2,458
School Buses............................................. 688 3,234 3,923
Short-Haul Single Unit Trucks............................ 688 2,706 3,394
Transit Buses............................................ 688 1,770 2,458
----------------------------------------------------------------------------------------------------------------
[[Page 4412]]
Table V-15--MY2027 CNG Heavy HDE Technology Costs per Vehicle Associated With the Final Program, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
Direct costs Indirect costs Costs per vehicle
----------------------------------------------------------------------------------------------------------------
FRM Baseline
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............................. 8,585 10,556 19,141
Other Buses.............................................. 8,585 10,556 19,141
Refuse Trucks............................................ 8,585 10,556 19,141
School Buses............................................. 8,585 10,556 19,141
Short-Haul Combination Trucks............................ 8,585 8,351 16,936
Short-Haul Single Unit Trucks............................ 8,585 10,556 19,141
----------------------------------------------------------------------------------------------------------------
FRM Baseline + Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............................. 8,610 17,988 26,598
Other Buses.............................................. 8,610 17,988 26,598
Refuse Trucks............................................ 8,610 17,988 26,598
School Buses............................................. 8,610 17,988 26,598
Short-Haul Combination Trucks............................ 8,610 12,577 21,187
Short-Haul Single Unit Trucks............................ 8,610 17,988 26,598
----------------------------------------------------------------------------------------------------------------
Increased Cost of the Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............................. 25 7,431 7,457
Other Buses.............................................. 25 7,431 7,457
Refuse Trucks............................................ 25 7,431 7,457
School Buses............................................. 25 7,431 7,457
Short-Haul Combination Trucks............................ 25 4,225 4,251
Short-Haul Single Unit Trucks............................ 25 7,431 7,457
----------------------------------------------------------------------------------------------------------------
Table V-16--MY2027 CNG Urban Bus Technology Costs per Vehicle Associated With the Final Program, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
Direct costs Indirect costs Costs per vehicle
----------------------------------------------------------------------------------------------------------------
FRM Baseline............................................. 6,438 5,367 11,806
FRM Baseline + Final Program............................. 6,457 13,490 19,948
Increased Cost of the Final Program...................... 19 8,123 8,142
----------------------------------------------------------------------------------------------------------------
B. Operating Costs
We have estimated three impacts on operating costs expected to be
incurred by users of new MY 2027 and later heavy-duty vehicles:
Increased diesel exhaust fluid (DEF) consumption by diesel vehicles due
to increased DEF dose rates to enable compliance with more stringent
NOX standards; decreased fuel costs for gasoline vehicles
due to new onboard refueling vapor recovery systems that allow burning
(in engine) of otherwise evaporated hydrocarbon emissions; emission
repair impacts brought about by longer warranty and useful life
provisions; and the potential higher emission-related repair costs for
vehicles equipped with the new technology. For the repair impacts, we
expect that the longer duration warranty period will result in lower
owner/operator-incurred repair costs due to fewer repairs being paid
for by owners/operators since more costs will be borne by the
manufacturer, and that the longer duration useful life periods will
result in increased emission control system durability. We have
estimated the net effect on repair costs and describe our approach,
along with increased DEF consumption and reduced gasoline consumption,
in this section. Additional details on our methodology and estimates of
operating costs are included in RIA Chapter 7.2.
1. Costs Associated With Increased Diesel Exhaust Fluid (DEF)
Consumption in Diesel Engines
Consistent with the approach used to estimate technology costs, we
have estimated both baseline case DEF consumption and DEF consumption
under the final program. For the baseline case, we estimated DEF
consumption using the relationship between DEF dose rate and the
reduction in NOX over the SCR catalyst. The relationship
between DEF dose rate and NOX reduction across the SCR
catalyst is based on methodology presented in the Technical Support
Document to the 2012 Nonconformance Penalty rule (the NCP Technical
Support Document, or NCP TSD).\443\ The relationship of DEF dose rate
to NOX reduction used in that methodology considered FTP
emissions and, as such, the DEF dose rate increased as FTP tailpipe
emissions decreased. The DEF dose rate used in this analysis is 5.18
percent of fuel consumed.
---------------------------------------------------------------------------
\443\ Nonconformance Penalties for On-highway Heavy-duty Diesel
Engines: Technical Support Document; EPA-420-R-12-014, August 2012.
---------------------------------------------------------------------------
To estimate DEF consumption impacts under the final program, which
involves not only the new FTP emission standards but also the new SET
and LLC standards along with new off-cycle standards, we developed a
new approach to estimate DEF consumption for the proposal, which we
also applied in this final rule. For this analysis, we scaled DEF
consumption with the NOX reductions achieved under the final
emission standards. This was done by considering the molar mass of
NOX, the molar mass of urea, the mass concentration of urea
in DEF, along with the density of DEF, to estimate the
[[Page 4413]]
theoretical gallons of DEF consumed per ton of NOX reduced.
We estimated theoretical DEF consumption per ton of NOX
reduced at 442 gallons/ton, which we then adjusted based on testing to
527 gallons/ton, the value used in this analysis. We describe this in
more detail in Section 7.2.1 of the RIA.
These two DEF consumption metrics--dose rate per gallon for an
engine meeting the baseline emission standards and any additional DEF
consumption per ton of NOX reduced to achieve the final
emission standards over the final useful lives--were used to estimate
total DEF consumption. These DEF consumption rates were then multiplied
by DEF price per gallon, adjusted to 2017 dollars from the DEF prices
presented in the NCP TSD, to arrive at the impacts on DEF costs for
diesel engines. These are shown for MY2027 diesel vehicles in Table V-
17. Because these are operating costs which occur over time, we present
them at both 3 and 7 percent discount rates.
Table V-17--MY2027 Lifetime DEF Costs per Diesel Vehicle Associated With Final NOX Standards, 2017 Dollars
--------------------------------------------------------------------------------------------------------------------------------------------------------
3% Discount rate 7% Discount rate
-----------------------------------------------------------------------------------------------
Light HDE Medium HDE Heavy HDE Urban bus Light HDE Medium HDE Heavy HDE Urban bus
--------------------------------------------------------------------------------------------------------------------------------------------------------
FRM Baseline
--------------------------------------------------------------------------------------------------------------------------------------------------------
Long-Haul Combination Trucks............................ .......... .......... 34,009 .......... .......... .......... 25,768 ..........
Long-Haul Single Unit Trucks............................ 3,759 5,686 6,823 .......... 2,937 4,443 5,331 ..........
Motor Homes............................................. .......... 1,489 1,764 .......... .......... 1,068 1,265 ..........
Other Buses............................................. 9,118 11,285 11,688 .......... 6,695 8,286 8,582 ..........
Refuse Trucks........................................... .......... 8,435 8,787 .......... .......... 6,317 6,581 ..........
School Buses............................................ 2,331 3,030 3,187 .......... 1,712 2,225 2,340 ..........
Short-Haul Combination Trucks........................... .......... 16,323 17,154 .......... .......... 12,735 13,384 ..........
Short-Haul Single Unit Trucks........................... 2,733 4,144 4,975 .......... 2,100 3,184 3,823 ..........
Transit Buses........................................... 9,192 11,254 .......... 11,742 6,750 8,263 .......... 8,622
--------------------------------------------------------------------------------------------------------------------------------------------------------
FRM Baseline + Final Program
--------------------------------------------------------------------------------------------------------------------------------------------------------
Long-Haul Combination Trucks............................ .......... .......... 37,621 .......... .......... .......... 28,580 ..........
Long-Haul Single Unit Trucks............................ 4,011 6,215 7,916 .......... 3,136 4,865 6,200 ..........
Motor Homes............................................. .......... 1,617 2,016 .......... .......... 1,162 1,450 ..........
Other Buses............................................. 9,805 12,277 13,594 .......... 7,209 9,040 10,011 ..........
Refuse Trucks........................................... .......... 9,182 10,246 .......... .......... 6,895 7,696 ..........
School Buses............................................ 2,501 3,293 3,671 .......... 1,839 2,424 2,702 ..........
Short-Haul Combination Trucks........................... .......... 17,575 19,378 .......... .......... 13,727 15,154 ..........
Short-Haul Single Unit Trucks........................... 2,949 4,573 5,864 .......... 2,268 3,522 4,517 ..........
Transit Buses........................................... 9,867 12,149 .......... 13,410 7,253 8,945 .......... 9,863
--------------------------------------------------------------------------------------------------------------------------------------------------------
Increased Cost of the Final Program
--------------------------------------------------------------------------------------------------------------------------------------------------------
Long-Haul Combination Trucks............................ .......... .......... 3,612 .......... .......... .......... 2,812 ..........
Long-Haul Single Unit Trucks............................ 252 529 1,094 .......... 199 422 869 ..........
Motor Homes............................................. .......... 128 253 .......... .......... 94 185 ..........
Other Buses............................................. 687 992 1,906 .......... 514 754 1,428 ..........
Refuse Trucks........................................... .......... 747 1,459 .......... .......... 579 1,115 ..........
School Buses............................................ 170 263 484 .......... 127 199 362 ..........
Short-Haul Combination Trucks........................... .......... 1,251 2,224 .......... .......... 992 1,771 ..........
Short-Haul Single Unit Trucks........................... 216 429 889 .......... 168 337 694 ..........
Transit Buses........................................... 675 896 .......... 1,669 504 681 .......... 1,241
--------------------------------------------------------------------------------------------------------------------------------------------------------
2. Costs Associated With Changes in Fuel Consumption on Gasoline
Engines
We have estimated a decrease in fuel costs, i.e., fuel savings,
associated with the final ORVR requirements on gasoline engines. Due to
the ORVR systems, evaporative emissions that would otherwise be emitted
into the atmosphere will be trapped and subsequently burned in the
engine. We describe the approach taken to estimate these impacts in
Chapter 7.2.2 of the RIA. These newly captured evaporative emissions
are converted to gallons and then multiplied by AEO 2019 reference case
gasoline prices (converted to 2017 dollars) to arrive at the monetized
impacts. These impacts are shown in Table V-18. In the aggregate, we
estimate that the ORVR requirements in the final program will result in
an annual reduction of approximately 0.3 million (calendar year 2027)
to 4.9 million (calendar year 2045) gallons of gasoline, representing
roughly 0.1 percent of gasoline consumption from impacted vehicles.
[[Page 4414]]
Table V-18--MY2027 Lifetime Fuel Costs per Gasoline Vehicle Associated With ORVR Requirements, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
3% Discount rate 7% Discount rate
-----------------------------------------------------------------------
Light HDE Medium HDE Heavy HDE Light HDE Medium HDE Heavy HDE
----------------------------------------------------------------------------------------------------------------
FRM Baseline
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............ 120,876 150,530 192,727 94,841 118,108 151,216
Motor Homes............................. 30,329 38,339 48,887 21,905 27,691 35,309
Other Buses............................. 273,223 .......... .......... 201,982 .......... ..........
School Buses............................ 69,242 .......... .......... 51,188 .......... ..........
Short-Haul Single Unit Trucks........... 86,494 109,427 139,754 66,791 84,501 107,918
Transit Buses........................... 269,797 .......... .......... 199,449 .......... ..........
----------------------------------------------------------------------------------------------------------------
FRM Baseline + Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............ 120,744 150,349 192,470 94,739 117,969 151,019
Motor Homes............................. 30,271 38,260 48,781 21,864 27,635 35,233
Other Buses............................. 272,656 .......... .......... 201,570 .......... ..........
School Buses............................ 69,110 .......... .......... 51,092 .......... ..........
Short-Haul Single Unit Trucks........... 86,397 109,292 139,566 66,717 84,399 107,777
Transit Buses........................... 269,245 .......... .......... 199,047 .......... ..........
----------------------------------------------------------------------------------------------------------------
Increased Cost of the Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............ -132 -181 -257 -102 -139 -197
Motor Homes............................. -58 -79 -106 -41 -56 -75
Other Buses............................. -567 .......... .......... -412 .......... ..........
School Buses............................ -132 .......... .......... -96 .......... ..........
Short-Haul Single Unit Trucks........... -97 -135 -187 -74 -102 -141
Transit Buses........................... -552 .......... .......... -402 .......... ..........
----------------------------------------------------------------------------------------------------------------
3. Emission-Related Repair Cost Impacts Associated With the Final
Program
The final extended warranty and useful life requirements will have
an impact on emission-related repair costs incurred by truck owners.
Researchers have noted the relationships among quality, reliability,
and warranty for a variety of goods.\444\ Wu,\445\ for instance,
examines how analyzing warranty data can provide ``early warnings'' on
product problems that can then be used for design modifications.
Guajardo et al. describe one of the motives for warranties to be
``incentives for the seller to improve product quality''; specifically
for light-duty vehicles, they find that buyers consider warranties to
substitute for product quality, and to complement service quality.\446\
Murthy and Jack, for new products, and Saidi-Mehrabad et al. for
second-hand products, consider the role of warranties in improving a
buyer's confidence in quality of the good.447 448
---------------------------------------------------------------------------
\444\ Thomas, M., and S. Rao (1999). ``Warranty Economic
Decision Models: A Summary and Some Suggested Directions for Future
Research.'' Operations Research 47(6):807-820.
\445\ Wu, S (2012). Warranty Data Analysis: A Review. Quality
and Reliability Engineering International 28: 795-805.
\446\ Guajardo, J., M Cohen, and S. Netessine (2016). ``Service
Competition and Product Quality in the U.S. Automobile Industry.''
Management Science 62(7):1860-1877. The other rationales are
protection for consumers against failures, provision of product
quality information to consumers, and a means to distinguish
consumers according to their risk preferences.
\447\ Murthy, D., and N. Jack (2009). ``Warranty and
Maintenance,'' Chapter 18 in Handbook of Maintenance Management and
Engineering, Mohamed Ben-Daya et al., editors. London: Springer.
\448\ Saidi-Mehrabad, M., R. Noorossana, and M. Shafiee (2010).
``Modeling and analysis of effective ways for improving the
reliability of second-hand products sold with warranty.''
International Journal of Advanced Manufacturing Technology 46: 253-
265.
---------------------------------------------------------------------------
On the one hand, we expect owner-incurred emission repair costs to
decrease due to the final program because the longer emission warranty
requirements will result in more repair costs covered by the OEMs.
Further, we expect improved serviceability in an effort by OEMs to
decrease the repair costs that they will incur. We also expect that the
longer useful life periods in the final standards will result in more
durable parts to ensure regulatory compliance over the longer
timeframe. On the other hand, we also expect that the more costly
emission control systems required by the final program may result in
higher repair costs which might increase owner-incurred costs outside
the warranty and/or useful life periods.
As discussed in Section V.A.2, we have estimated increased OEM
costs associated with increased warranty liability (i.e., longer
warranty periods), and for more durable parts resulting from the longer
useful life periods. These costs are accounted for via increased
warranty costs and increased research and development (R&D) costs. We
also included additional aftertreatment costs in the direct
manufacturing costs to address the increased useful life requirements
(e.g., larger catalyst volume; see Chapters 2 and 3 of the RIA for
detailed discussions). We estimate that the new useful life and
warranty provisions will help to reduce emission repair costs during
the emission warranty and regulatory useful life periods, and possibly
beyond.
In the proposal, to estimate impacts on emission repair costs, we
began with an emission repair cost curve derived from an industry white
paper.\449\ Some commenters took exception to the approach we took,
preferring instead that we use what they consider to be a more
established repair and maintenance cost estimate from the American
Transportation Research
[[Page 4415]]
Institute.\450\ After careful consideration of the ATRI data, we
derived a cost per mile value for repair and maintenance based on the
10 years of data gathered and presented. We chose to use the ATRI data
in place of the data used in the proposal because it constituted 10
years of data from an annually prepared study compared to the one year
of data behind the study used in the proposal.
---------------------------------------------------------------------------
\449\ See ``Mitigating Rising Maintenance & Repair Costs for
Class-8 Truck Fleets, Effective Data & Strategies to Leverage Newer
Trucks to Reduce M&R Costs,'' Fleet Advantage Whitepaper Series,
2018.
\450\ ``An Analysis of the Operational Costs of Trucking: 2021
Update,'' American Transportation Research Institute, November 2021.
---------------------------------------------------------------------------
Because the ATRI data represent heavy HD combination vehicles it
was necessary for us to scale the ATRI values for applicability to HD
vehicles with different sized engines having different emission-control
system costs. We have done this in the same way as was discussed
earlier for scaling of warranty cost (see Table V-6). Given that future
engines and vehicles will be equipped with new, more costly technology,
it is possible that the repair costs for vehicles under the final
program will be higher than the repair costs in the baseline. We have
included such an increase for the period beyond useful life. This is
perhaps conservative because it seems reasonable to assume that the R&D
used to improve durability during the useful life period would also
improve durability beyond it. Nonetheless, we also think it is
reasonable to include an increase in repair costs, relative to the
baseline case, because the period beyond useful life is of marginally
less concern to manufacturers.\451\ Lastly, since our warranty and
useful life provisions pertain to emissions-related systems and their
repair, we adjusted the ATRI values by 10.8 percent to arrive at an
emission-related repair cost. The 10.8 percent value was similarly used
in the proposal and was derived by EPA using data in the Fleet
Advantage Whitepaper. Table V-19 shows how we have scaled the repair
and maintenance costs derived from the ATRI study.
---------------------------------------------------------------------------
\451\ This is not meant to suggest that manufacturers no longer
care about their products beyond their regulatory useful life, but
rather to reflect the expectation that regulatory pressures--i.e.,
regulatory compliance during the useful life--tend to focus
manufacturer resources.
---------------------------------------------------------------------------
Importantly, during the warranty period, there are no emission-
related repair costs incurred by owner/operators since those will be
covered under warranty.
Table V-19--Scaling Approach Used in Estimating Baseline Emission-Related Repair Costs per Mile, 2017 Cents *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Repair & maintenance Emission-related repair
------------------------------ (10.8% of repair &
MOVES regulatory class Scaling approach maintenance)
Diesel Gasoline CNG -----------------------------
Diesel Gasoline CNG
--------------------------------------------------------------------------------------------------------------------------------------------------------
Light HDE................................... Base Light HDE DMC/Base Diesel Heavy HDE DMC.. 10.1 7.28 ........ 1.09 0.79 ........
Medium HDE.................................. Base Medium HDE DMC/Base Diesel Heavy HDE DMC. 10.3 7.28 ........ 1.12 0.79 ........
Heavy HDE................................... Base Heavy HDE DMC/Base Diesel Heavy HDE DMC.. 15.8 7.28 23.2 1.71 0.79 2.52
Urban bus................................... Base Urban bus DMC/Base Diesel Heavy HDE DMC.. 9.80 ........ 16.2 1.06 ........ 1.75
--------------------------------------------------------------------------------------------------------------------------------------------------------
* The Base Diesel Heavy HDE DMC would be the $5,816 value shown in Table V-2; shown is scaling of baseline emission-repair costs per mile although we
also scaled emission-repair cost per hour and applied those values for most vocational vehicles; this is detailed in Chapter 7.2.3 of the final RIA.
We present more details in Chapter 7 of the RIA behind the
emission-repair cost values we are using, the scaling used and the 10.8
percent emission-related repair adjustment factor and how it was
derived. As done for warranty costs, we have used estimated ages for
when warranty and useful life are reached, using the required miles,
ages and hours along with the estimated miles driven and hours of
operation for each specific type of vehicle. This means that warranty
and useful life ages are reached in different years for different
vehicles, even if they belong to the same service class and have the
same regulatory warranty and useful life periods. For example, we
expect warranty and useful life ages to be attained at different points
in time by a long-haul combination truck driving over 100,000 miles per
year or over 2,000 hours per year and a refuse truck driven around
40,000 miles per year or operating less than 1,000 hours per year. The
resultant MY2027 lifetime emission-related repair costs are shown in
Table V-20 for diesel HD vehicles, in Table V-21 for gasoline HD
vehicles, and in Table V-22 for CNG HD vehicles. Since these costs
occur over time, we present them using both a 3 percent and a 7 percent
discount rate. Note that these costs assume that all emission-related
repair costs are paid by manufacturers during the warranty period, and
beyond the warranty period the emission-related repair costs are
incurred by owners/operators.
Table V-20--MY2027 Lifetime Emission-Related Repair Costs per Diesel Vehicle, 2017 Dollars
--------------------------------------------------------------------------------------------------------------------------------------------------------
3% Discount rate 7% Discount rate
-----------------------------------------------------------------------------------------------
Light HDE Medium HDE Heavy HDE Urban bus Light HDE Medium HDE Heavy HDE Urban bus
--------------------------------------------------------------------------------------------------------------------------------------------------------
FRM Baseline
--------------------------------------------------------------------------------------------------------------------------------------------------------
Long-Haul Combination Trucks............................ .......... .......... 22,041 .......... .......... .......... 16,138 ..........
Long-Haul Single Unit Trucks............................ 3,208 2,493 3,060 .......... 2,440 1,790 2,109 ..........
Motor Homes............................................. .......... 613 936 .......... .......... 394 602 ..........
Other Buses............................................. 4,292 3,668 4,719 .......... 3,083 2,499 3,074 ..........
Refuse Trucks........................................... .......... 2,222 3,110 .......... .......... 1,506 2,065 ..........
School Buses............................................ 1,148 1,050 1,604 .......... 771 684 1,045 ..........
Short-Haul Combination Trucks........................... .......... 6,635 8,088 .......... .......... 5,003 5,823 ..........
Short-Haul Single Unit Trucks........................... 1,799 1,292 1,973 .......... 1,318 876 1,338 ..........
[[Page 4416]]
Transit Buses........................................... 4,242 3,625 .......... 3,941 3,047 2,469 .......... 2,732
--------------------------------------------------------------------------------------------------------------------------------------------------------
FRM Baseline + Final Program
--------------------------------------------------------------------------------------------------------------------------------------------------------
Long-Haul Combination Trucks............................ .......... .......... 25,070 .......... .......... .......... 17,497 ..........
Long-Haul Single Unit Trucks............................ 2,284 1,531 1,524 .......... 1,509 956 906 ..........
Motor Homes............................................. .......... 480 728 .......... .......... 272 415 ..........
Other Buses............................................. 4,090 3,261 3,454 .......... 2,598 1,978 1,979 ..........
Refuse Trucks........................................... .......... 1,408 2,038 .......... .......... 819 1,180 ..........
School Buses............................................ 667 772 1,174 .......... 378 439 673 ..........
Short-Haul Combination Trucks........................... .......... 7,029 6,436 .......... .......... 4,960 4,225 ..........
Short-Haul Single Unit Trucks........................... 764 721 1,115 .......... 451 421 655 ..........
Transit Buses........................................... 4,042 3,224 .......... 2,394 2,567 1,955 .......... 1,370
--------------------------------------------------------------------------------------------------------------------------------------------------------
Increased Cost of the Final Program
--------------------------------------------------------------------------------------------------------------------------------------------------------
Long-Haul Combination Trucks............................ .......... .......... 3,028 .......... .......... .......... 1,359 ..........
Long-Haul Single Unit Trucks............................ -924 -962 -1,536 .......... -931 -834 -1,203 ..........
Motor Homes............................................. .......... -132 -207 .......... .......... -122 -187 ..........
Other Buses............................................. -203 -406 -1,265 .......... -486 -520 -1,095 ..........
Refuse Trucks........................................... .......... -814 -1,072 .......... .......... -687 -885 ..........
School Buses............................................ -481 -278 -430 .......... -393 -245 -372 ..........
Short-Haul Combination Trucks........................... .......... 394 -1,651 .......... .......... -43 -1,598 ..........
Short-Haul Single Unit Trucks........................... -1,035 -570 -857 .......... -867 -455 -684 ..........
Transit Buses........................................... -200 -402 .......... -1,547 -480 -514 .......... -1,362
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table V-21--MY2027 Lifetime Emission-Related Repair Costs per Gasoline Vehicle, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
3% Discount rate 7% Discount rate
-----------------------------------------------------------------------
Light HDE Medium HDE Heavy HDE Light HDE Medium HDE Heavy HDE
----------------------------------------------------------------------------------------------------------------
FRM Baseline
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............ 2,324 2,324 2,324 1,768 1,768 1,768
Motor Homes............................. 431 431 431 278 278 278
Other Buses............................. 3,111 .......... .......... 2,234 .......... ..........
School Buses............................ 832 .......... .......... 559 .......... ..........
Short-Haul Single Unit Trucks........... 1,304 1,304 1,304 955 955 955
Transit Buses........................... 3,074 .......... .......... 2,208 .......... ..........
----------------------------------------------------------------------------------------------------------------
FRM Baseline + Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............ 1,831 1,831 1,831 1,271 1,271 1,271
Motor Homes............................. 275 275 275 156 156 156
Other Buses............................. 2,898 .......... .......... 1,917 .......... ..........
School Buses............................ 442 .......... .......... 252 .......... ..........
Short-Haul Single Unit Trucks........... 764 764 764 483 483 483
Transit Buses........................... 2,865 .......... .......... 1,895 .......... ..........
----------------------------------------------------------------------------------------------------------------
Increased Cost of the Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks............ -493 -493 -493 -497 -497 -497
Motor Homes............................. -156 -156 -156 -122 -122 -122
Other Buses............................. -212 .......... .......... -317 .......... ..........
School Buses............................ -390 .......... .......... -306 .......... ..........
Short-Haul Single Unit Trucks........... -540 -540 -540 -471 -471 -471
Transit Buses........................... -210 .......... .......... -313 .......... ..........
----------------------------------------------------------------------------------------------------------------
[[Page 4417]]
Table V-22--MY2027 Lifetime Emission-Related Repair Costs per CNG Vehicle, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
3% Discount rate 7% Discount rate
-----------------------------------------------
Heavy HDE Urban bus Heavy HDE Urban bus
----------------------------------------------------------------------------------------------------------------
FRM Baseline
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks.................................... 4,517 .......... 3,113 ..........
Other Buses..................................................... 6,966 .......... 4,537 ..........
Refuse Trucks................................................... 4,590 .......... 3,048 ..........
School Buses.................................................... 2,368 .......... 1,542 ..........
Short-Haul Combination Trucks................................... 11,938 .......... 8,595 ..........
Short-Haul Single Unit Trucks................................... 2,912 .......... 1,975 ..........
Transit Buses................................................... .......... 6,532 .......... 4,529
----------------------------------------------------------------------------------------------------------------
FRM Baseline + Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks.................................... 1,720 .......... 1,029 ..........
Other Buses..................................................... 3,807 .......... 2,194 ..........
Refuse Trucks................................................... 2,260 .......... 1,317 ..........
School Buses.................................................... 1,294 .......... 746 ..........
Short-Haul Combination Trucks................................... 7,723 .......... 5,143 ..........
Short-Haul Single Unit Trucks................................... 1,248 .......... 737 ..........
Transit Buses................................................... .......... 2,822 .......... 1,626
----------------------------------------------------------------------------------------------------------------
Increased Cost of the Final Program
----------------------------------------------------------------------------------------------------------------
Long-Haul Single Unit Trucks.................................... -2,797 .......... -2,084 ..........
Other Buses..................................................... -3,158 .......... -2,344 ..........
Refuse Trucks................................................... -2,330 .......... -1,732 ..........
School Buses.................................................... -1,074 .......... -797 ..........
Short-Haul Combination Trucks................................... -4,215 .......... -3,452 ..........
Short-Haul Single Unit Trucks................................... -1,664 .......... -1,238 ..........
Transit Buses................................................... .......... -3,710 .......... -2,903
----------------------------------------------------------------------------------------------------------------
C. Program Costs
Using the cost elements outlined in Sections V.A and V.B, we have
estimated the costs associated with the final program. Costs are
presented in more detail in Chapter 7 of the RIA. As noted earlier,
costs are presented in 2017 dollars in undiscounted annual values along
with present values (PV) and equivalent annualized values (EAV) at both
3 and 7 percent discount rates with values discounted to the 2027
calendar year.
Table V-23--Total Technology & Operating Cost Impacts of the Final Program Relative to the Baseline Case, All Regulatory Classes and All Fuels, Billions
of 2017 Dollars \a\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Direct Indirect Other Total Emission Total
Calendar year tech warranty Indirect indirect Indirect tech repair Urea Fuel cost operating Program
cost cost R&D cost cost profit cost cost cost cost cost
--------------------------------------------------------------------------------------------------------------------------------------------------------
2027................................ 1.1 2.1 0.21 0.34 0.058 3.8 0.00 0.06 -0.0004 0.057 3.9
2028................................ 1.1 2.1 0.20 0.32 0.055 3.7 -0.05 0.12 -0.0008 0.07 3.8
2029................................ 1.0 2.1 0.19 0.31 0.053 3.7 -0.30 0.18 -0.0013 -0.12 3.6
2030................................ 1.0 2.1 0.051 0.30 0.052 3.5 -0.43 0.25 -0.0017 -0.19 3.4
2031................................ 1.0 2.2 0.050 0.30 0.051 3.6 -0.50 0.33 -0.0022 -0.17 3.4
2032................................ 0.99 2.2 0.049 0.29 0.050 3.6 -0.57 0.41 -0.0027 -0.16 3.4
2033................................ 0.98 2.2 0.049 0.29 0.050 3.6 -0.61 0.47 -0.0034 -0.14 3.5
2034................................ 0.98 2.3 0.049 0.29 0.049 3.6 -0.64 0.53 -0.0041 -0.11 3.5
2035................................ 0.96 2.3 0.048 0.28 0.049 3.7 -0.66 0.58 -0.0048 -0.08 3.6
2036................................ 0.95 2.3 0.048 0.28 0.048 3.7 -0.66 0.63 -0.0054 -0.04 3.6
2037................................ 0.95 2.4 0.048 0.28 0.048 3.7 -0.60 0.68 -0.0060 0.07 3.8
2038................................ 0.95 2.4 0.048 0.28 0.048 3.7 -0.54 0.72 -0.0066 0.17 3.9
2039................................ 0.95 2.5 0.047 0.28 0.048 3.8 -0.49 0.76 -0.0072 0.27 4.0
2040................................ 0.95 2.5 0.047 0.28 0.048 3.8 -0.45 0.80 -0.0078 0.34 4.2
2041................................ 0.95 2.5 0.047 0.28 0.048 3.9 -0.41 0.84 -0.0083 0.41 4.3
2042................................ 0.95 2.6 0.047 0.28 0.048 3.9 -0.39 0.87 -0.0088 0.47 4.4
2043................................ 0.95 2.6 0.047 0.28 0.048 3.9 -0.37 0.91 -0.0093 0.53 4.5
2044................................ 0.95 2.7 0.048 0.28 0.048 4.0 -0.35 0.94 -0.0097 0.57 4.6
2045................................ 0.95 2.7 0.048 0.28 0.048 4.1 -0.34 0.97 -0.010 0.62 4.7
PV, 3%.............................. 14 33 1.1 4.2 0.72 53 -6.2 7.7 -0.069 1.4 55
PV, 7%.............................. 10 24 0.90 3.0 0.52 38 -4.3 4.9 -0.043 0.60 39
EAV, 3%............................. 1.0 2.3 0.078 0.29 0.050 3.7 -0.43 0.54 -0.0048 0.099 3.8
[[Page 4418]]
EAV, 7%............................. 1.0 2.3 0.087 0.29 0.051 3.7 -0.42 0.48 -0.0042 0.058 3.8
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Values show 2 significant digits; negative cost values denote savings; calendar year values are undiscounted, present values are discounted to 2027;
Program Cost is the sum of Total Tech Cost and Total Operating Cost. Note also that the Information Collection Request costs addressed in Section XII
would fall within the ``Other'' indirect costs shown here.
VI. Estimated Emissions Reductions From the Final Program
The final program, which is described in detail in Sections III and
IV, is expected to reduce emissions from highway heavy-duty engines in
several ways. We project the final emission standards for heavy-duty CI
engines will reduce tailpipe emissions of NOX; the
combination of the final low-load test cycle and off-cycle test
procedure for CI engines will help to ensure that the reductions in
tailpipe emissions are achieved in-use, not only under high-speed, on-
highway conditions, but also under low-load and idle conditions. We
also project reduced tailpipe emissions of NOX, CO, PM,
VOCs, and associated air toxics from the final emission standards for
heavy-duty SI engines, particularly under cold-start and high-load
operating conditions. The longer emission warranty and regulatory
useful life requirements for heavy-duty CI and SI engines in the final
rule will help maintain the expected emission reductions for all
pollutants, including primary exhaust PM2.5, throughout the
useful life of the engine. The onboard refueling vapor recovery
requirements for heavy-duty SI engines in the final rule will reduce
VOCs and associated air toxics. See RIA Chapter 5.3 for details on
projected emission reductions of each pollutant.
Section VI.A provides an overview of the methods used to estimate
emission reductions from our final program. All the projected emission
reductions from the final program are outlined in Section VI.B, with
more details provided in the RIA Chapter 5. Section VI.C presents
projected emission reductions from the final program by engine
operations and processes (e.g., medium-to-high load or low-load engine
operations).
A. Emission Inventory Methodology
To estimate the emission reductions from the final program, we used
the current public version of EPA's Motor Vehicle Emission Simulator
(MOVES) model, MOVES3. MOVES3 includes all the model updates previously
made for the version of the MOVES model used for the NPRM analysis
(``MOVES CTI NPRM''), as well as other more recent updates. Detailed
descriptions of the underlying data and analyses that informed the
model updates are discussed in Chapter 5.2 of the RIA and documented in
peer-reviewed technical reports referenced in the RIA. Inputs developed
to model the national emission inventories for the final program are
also discussed in Chapter 5.2.2 of the RIA.
B. Estimated Emission Reductions From the Final Program
As discussed in Sections III and IV, the final program includes
new, more stringent numeric emission standards, as well as longer
regulatory useful life and emissions warranty periods compared to
today's standards. Our estimates of the emission impacts of the final
program in calendar years 2030, 2040, and 2045 are presented in Table
VI-1. As shown in Table VI-1, we estimate that the final program will
reduce NOX emissions from highway heavy-duty vehicles by 48
percent nationwide in 2045. We also estimate an eight percent reduction
in primary exhaust PM2.5 from highway heavy-duty vehicles.
VOC emissions from heavy-duty vehicles will be 23 percent lower.
Emissions of CO from heavy-duty vehicles are estimated to decrease by
18 percent. Reductions in heavy-duty vehicle emissions of other
pollutants, including air toxics, range from an estimated reduction of
about 28 percent for benzene to about seven percent change in
acetaldehyde. RIA Chapter 5.5.2 includes additional details on the
emission reductions by vehicle fuel type; Chapter 5.5.4 provides our
estimates of criteria pollutant emissions reductions for calendar years
2027 through 2045.
As the final program is implemented, emission reductions are
expected to increase over time as the fleet turns over to new,
compliant engines. We estimate no change in CO2 emissions
from the final program, based on data in our feasibility and cost
analyses of the final program (see Section III for more
discussion).\452\
---------------------------------------------------------------------------
\452\ This estimate includes the assumption that vehicle sales
will not change in response to the final rule. See Section X for
further discussion on vehicle sales impacts of this final rule.
Table VI-1--Annual Emission Reductions From Heavy-Duty Vehicles in Calendar Years (CY) 2030, 2040, and 2045--
Emissions With Final Program in Place Relative to the Heavy-Duty Vehicle Emissions Baseline
----------------------------------------------------------------------------------------------------------------
CY2030 CY2040 CY2045
-----------------------------------------------------------------------------
Pollutant US short US short US short
tons % reduction tons % reduction tons % reduction
----------------------------------------------------------------------------------------------------------------
NOX............................... 139,677 14 398,864 44 453,239 48
VOC............................... 5,018 5 17,139 20 20,758 23
Primary Exhaust PM2.5............. 115 1 491 7 566 8
CO................................ 43,978 3 208,935 16 260,750 18
Acetaldehyde...................... 36 2 124 6 145 7
Benzene........................... 40 4 177 23 221 28
Formaldehyde...................... 29 1 112 7 134 8
[[Page 4419]]
Naphthalene....................... 2 1 7 13 9 16
----------------------------------------------------------------------------------------------------------------
C. Estimated Emission Reductions by Engine Operations and Processes
Looking more closely at the NOX emission inventory from
highway heavy-duty vehicles, our analysis shows that the final
standards will reduce emissions across several engine operations and
processes, with the greatest reductions attributable to medium-to-high
load engine operations, low-load engine operations, and age effects
(Table VI-2). Emission reductions attributable to medium-to-high load
engine operations are based on changes in the new numeric emissions
standards compared to existing standards and corresponding test
procedures, as described in preamble Section III. Emission reductions
attributable to the age effects category are based on longer useful
life and warranty periods in the final rule, which are described in
preamble Section IV.
Table 5-13 in Chapter 5.2.2 of the RIA shows that tampering and
mal-maintenance significantly increases emissions from current heavy
heavy-duty engines (e.g., we estimate a 500 percent increase in
NOX emissions for heavy heavy-duty vehicles due to
NOX aftertreatment malfunction). Absent the final rule,
these substantial increases in emissions from tampering and mal-
maintenance could potentially have large impact on the HD
NOX inventory. However, the longer regulatory useful life
and emission-related warranty requirements in the final rule will
ensure that more stringent standards are met for a longer period of
time while the engines are in use. Specifically, we estimate 18 percent
fewer NOX emissions in 2045 due to the longer useful life
and warranty periods reducing the likelihood of tampering and mal-
maintenance after the current useful life periods of heavy-duty CI
engines.453 454 We note that these estimates of emissions
impacts from tampering and mal-maintenance of heavy-duty engines
reflect currently available data and may not fully reflect the extent
of emissions impacts from tampering or mal-maintenance; thus,
additional data on the emissions impacts of heavy-duty tampering and
mal-maintenance may show that there would be additional emissions
reductions from the final rule.
---------------------------------------------------------------------------
\453\ See Chapter 5.2.2 of the RIA for a discussion of how we
calculate the emission rates due to the final useful life and
warranty periods for Light, Medium, and Heavy heavy-duty engines.
\454\ Although we anticipate emission benefits from the
lengthened warranty and useful life periods from gasoline and NG-
fueled vehicles, they were not included in the analysis done for the
final rule (see RIA Chapter 5.2 for details).
---------------------------------------------------------------------------
Further, due to insufficient data, we are currently unable to
quantify the impacts of other provisions to improve maintenance and
serviceability of emission controls systems (e.g., updated maintenance
intervals, requiring manufacturers to provide more information on how
to diagnose and repair emission control systems, as described in
preamble Section IV). We expect the final provisions to improve
maintenance and serviceability will reduce incentives to tamper with
the emission control systems on MY 2027 and later engines, which would
avoid large increases in emissions that would impact the reductions
projected from the final rule. For example, we estimate a greater than
3000 percent increase in NOX emissions for heavy heavy-duty
vehicles due to malfunction of the NOX emissions
aftertreatment on a MY 2027 and later heavy heavy-duty vehicle. As
such, the maintenance and serviceability provisions combined with the
longer useful life and warranty periods will provide a comprehensive
approach to ensure that the new, much more stringent emissions
standards are met during in use operations.
Table VI-2 compares NOX emissions in 2045 from different
engine operations and processes with and without the final standards. A
graphical comparison of NOX emissions by process is included
in RIA Chapter 5.5.3.
Table VI-2--Heavy-Duty NOX Emission Reductions by Process in CY2045
[US tons]
----------------------------------------------------------------------------------------------------------------
Emission inventory Percent Emission inventory
Engine operation or process contribution without Tons reduction from contribution with
final program (%) reduced baseline final program (%)
----------------------------------------------------------------------------------------------------------------
Medium- to High-Load................. 36 217,708 64 24
Low-Load............................. 30 177,967 63 21
Aging................................ 22 35,750 18 34
Extended Idle & APU.................. 2 11,692 63 1
Starts............................... 5 10,122 23 7
Historical Fleet (MY 2010 to 2026)... 6 0 0 12
----------------------------------------------------------------------------------------------------------------
VII. Air Quality Impacts of the Final Rule
As discussed in Section VI, we project the standards in the final
rule will result in meaningful reductions in emissions of
NOX, VOC, CO and PM2.5. When feasible, we conduct
full-scale photochemical air quality modeling to accurately project
levels of criteria and air toxic pollutants, because the atmospheric
chemistry related to ambient concentrations of PM2.5, ozone,
[[Page 4420]]
and air toxics is very complex. Air quality modeling was performed for
the proposed rule and demonstrated improvements in concentrations of
air pollutants. Given the similar structure of the proposed and final
programs, the geographic distribution of emissions reductions and
modeled improvements in air quality are consistent and demonstrate that
the final rule will lead to substantial improvements in air
quality.\455\
---------------------------------------------------------------------------
\455\ Additional detail on the air quality modeling inventory
used in the proposed rule, along with the final rule emission
reductions, can be found in Chapter 5 of the RIA.
---------------------------------------------------------------------------
Specifically, we expect this rule will decrease ambient
concentrations of air pollutants, including significant improvements in
ozone concentrations in 2045 as demonstrated in the air quality
modeling analysis. We also expect reductions in ambient
PM2.5, NO2 and CO due to this rule. Although the
spatial resolution of the air quality modeling is not sufficient to
quantify it, this rule's emission reductions will also reduce air
pollution in close proximity to major roadways, where concentrations of
many air pollutants are elevated and where people of color and people
with low income are disproportionately exposed.
The emission reductions provided by the final standards will be
important in helping areas attain the NAAQS and prevent future
nonattainment. In addition, the final standards are expected to result
in improvements in nitrogen deposition and visibility. Additional
information and maps showing expected changes in ambient concentrations
of air pollutants in 2045 are included in the proposal, Chapter 6 of
the RIA and in the Air Quality Modeling Technical Support Document from
the proposed rule.456 457
---------------------------------------------------------------------------
\456\ USEPA (2021) Technical Support Document: Air Quality
Modeling for the HD 2027 Proposal. EPA-HQ-OAR-2019-0055. October
2021.
\457\ Section VII of the proposed rule preamble, 87 FR 17414
(March 28, 2022).
---------------------------------------------------------------------------
The proposed rule air quality modeling analysis consisted of a base
case, reference scenario, and control scenario. The ``base'' case
represents 2016 air quality. The ``reference'' scenario represents
projected 2045 air quality without the proposed rule and the
``control'' scenario represents projected 2045 emissions with the
proposed rule. Air quality modeling was done for the future year 2045
when the program will be fully implemented and when most of the
regulated fleet will have turned over.
A. Ozone
The scenario modeled for the proposed rule reduced 8-hour ozone
design values significantly in 2045. Ozone design values decreased by
more than 2 ppb in over 150 counties, and over 200 additional modeled
counties are projected to have decreases in ozone design values of
between 1 and 2 ppb in 2045. Our modeling projections indicate that
some counties will have design values above the level of the 2015 NAAQS
in 2045, and the rule will help those counties, as well as other
counties, in reducing ozone concentrations. Table VII-1 shows the
average projected change in 2045 8-hour ozone design values due to the
modeled scenario. Counties within 10 percent of the level of the NAAQS
are intended to reflect counties that, although not violating the
standard, would also be affected by changes in ambient levels of ozone
as they work to ensure long-term attainment or maintenance of the ozone
NAAQS. The projected changes in design values, summarized in Table VII-
1, indicate in different ways the overall improvement in ozone air
quality due to emission reductions from the modeled scenario.
Table VII-1--Average Change in Projected 8-Hour Ozone Design Values in 2045 Due to the Rule
----------------------------------------------------------------------------------------------------------------
Population-
Number of 2045 Average change weighted average
Projected design value category counties Population \a\ in 2045 design change in design
value (ppb) value (ppb)
----------------------------------------------------------------------------------------------------------------
all modeled counties.......................... 457 246,949,949 -1.87 -2.23
counties with 2016 base year design values 118 125,319,158 -2.12 -2.43
above the level of the 2015 8-hour ozone
standard.....................................
counties with 2016 base year design values 245 93,417,097 -1.83 -2.10
within 10% of the 2015 8-hour ozone standard.
counties with 2045 reference design values 15 37,758,488 -2.26 -3.03
above the level of the 2015 8-hour ozone
standard.....................................
counties with 2045 reference design values 56 39,302,665 -1.78 -2.02
within 10% of the 2015 8-hour ozone standard.
counties with 2045 control design values above 10 27,930,138 -2.36 -3.34
the level of the 2015 8-hour ozone standard..
counties with 2045 control design values 42 31,395,617 -1.69 -1.77
within 10% of the 2015 8-hour ozone standard.
----------------------------------------------------------------------------------------------------------------
\a\ Population numbers based on Woods & Poole data. Woods & Poole Economics, Inc. (2015). Complete Demographic
Database. Washington, DC. http://www.woodsandpoole.com/index.php.
B. Particulate Matter
The scenario modeled for the proposed rule reduced 24-hour and
annual PM2.5 design values in 2045. Annual PM2.5
design values in the majority of modeled counties decreased by between
0.01 and 0.05 [mu]g/m\3\ and by greater than 0.05 [mu]g/m\3\ in over 75
additional counties. 24-hour PM2.5 design values decreased
by between 0.15 and 0.5 [mu]g/m\3\ in over 150 counties and by greater
than 0.5 [mu]g/m\3\ in 5 additional counties. Our modeling projections
indicate that some counties will have design values above the level of
the 2012 PM2.5 NAAQS in 2045 and the rule will help those
counties, as well as other counties, in reducing PM2.5
concentrations. Table VII-2 and Table VII-3 present the average
projected changes in 2045 annual and 24-hour PM2.5 design
values. Counties within 10 percent of the level of the NAAQS are
intended to reflect counties that, although not violating the
standards, would also be affected by changes in ambient levels of
PM2.5 as they work to ensure long-term attainment or
maintenance of the annual and/or 24-hour PM2.5 NAAQS. The
projected changes in PM2.5 design values, summarized in
Table VII-2 and Table VII-3, indicate in different ways the overall
improvement in PM2.5 air quality due to the emission
reductions resulting from the modeled scenario. We expect this rule's
reductions in directly emitted PM2.5 will also contribute to
reductions in PM2.5 concentrations near roadways, although
our air quality modeling is not of sufficient resolution to capture
that impact.
[[Page 4421]]
Table VII-2--Average Change in Projected Annual PM2.5 Design Values in 2045 Due to the Rule
----------------------------------------------------------------------------------------------------------------
Population-
Number of 2045 Average change weighted average
Projected design value category counties Population \a\ in 2045 design change in design
value (ug/m3) value (ug/m3)
----------------------------------------------------------------------------------------------------------------
all modeled counties.......................... 568 273,604,437 -0.04 -0.04
counties with 2016 base year design values 17 26,726,354 -0.09 -0.05
above the level of the 2012 annual PM2.5
standard.....................................
counties with 2016 base year design values 5 4,009,527 -0.06 -0.06
within 10% of the 2012 annual PM2.5 standard.
counties with 2045 reference design values 12 25,015,974 -0.10 -0.05
above the level of the 2012 annual PM2.5
standard.....................................
counties with 2045 reference design values 6 1,721,445 -0.06 -0.06
within 10% of the 2012 annual PM2.5 standard.
counties with 2045 control design values above 10 23,320,070 -0.10 -0.05
the level of the 2012 annual PM2.5 standard..
counties with 2045 control design values 8 3,417,349 -0.08 -0.09
within 10% of the 2012 annual PM2.5 standard.
----------------------------------------------------------------------------------------------------------------
\a\ Population numbers based on Woods & Poole data. Woods & Poole Economics, Inc. (2015). Complete Demographic
Database. Washington, DC. http://www.woodsandpoole.com/index.php.
Table VII-3--Average Change in Projected 24-Hour PM2.5 Design Values in 2045 Due to the Rule
----------------------------------------------------------------------------------------------------------------
Population-
Number of 2045 Average change weighted average
Projected design value category counties Population \a\ in 2045 design change in design
value (ug/m3) value (ug/m3)
----------------------------------------------------------------------------------------------------------------
all modeled counties.......................... 568 272,852,777 -0.12 -0.17
counties with 2016 base year design values 33 28,394,253 -0.40 -0.67
above the level of the 2006 daily PM2.5
standard.....................................
counties with 2016 base year design values 15 13,937,416 -0.18 -0.27
within 10% of the 2006 daily PM2.5 standard..
counties with 2045 reference design values 29 14,447,443 -0.38 -0.55
above the level of the 2006 daily PM2.5
standard.....................................
counties with 2045 reference design values 12 22,900,297 -0.30 -0.59
within 10% of the 2006 daily PM2.5 standard..
counties with 2045 control design values above 29 14,447,443 -0.38 -0.55
the level of the 2006 daily PM2.5 standard...
counties with 2045 control design values 10 19,766,216 -0.26 -0.60
within 10% of the 2006 daily PM2.5 standard..
----------------------------------------------------------------------------------------------------------------
\a\ Population numbers based on Woods & Poole data. Woods & Poole Economics, Inc. (2015). Complete Demographic
Database. Washington, DC. http://www.woodsandpoole.com/index.php.
C. Nitrogen Dioxide
The scenario modeled for the proposed rule decreased annual
NO2 concentrations in most urban areas and along major
roadways by more than 0.3 ppb and decreased annual NO2
concentrations by between 0.01 and 0.1 ppb across much of the rest of
the country in 2045. The emissions reductions in the modeled scenario
will also likely decrease 1-hour NO2 concentrations and help
any potential nonattainment areas attain and maintenance areas maintain
the NO2 standard.\458\ We expect this rule will also
contribute to reductions in NO2 concentrations near
roadways, although our air quality modeling is not of sufficient
resolution to capture that impact. Section 6.4.4 of the RIA contains
more detail on the impacts of the rule on NO2
concentrations.
---------------------------------------------------------------------------
\458\ As noted in Section II, there are currently no
nonattainment areas for the NO2 NAAQS.
---------------------------------------------------------------------------
D. Carbon Monoxide
The scenario modeled for the proposed rule decreased annual CO
concentrations by more than 0.5 ppb in many urban areas and decreased
annual CO concentrations by between 0.02 and 0.5 ppb across much of the
rest of the country in 2045. The emissions reductions in the modeled
scenario will also likely decrease 1-hour and 8-hour CO concentrations
and help any potential nonattainment areas attain and maintenance areas
maintain the CO standard.\459\ Section 6.4.5 of the RIA contains more
detail on the impacts of the rule on CO concentrations.
---------------------------------------------------------------------------
\459\ As noted in Section II, there are currently no
nonattainment areas for the CO NAAQS.
---------------------------------------------------------------------------
E. Air Toxics
In general, the scenario modeled for the proposed rule had
relatively little impact on national average ambient concentrations of
the modeled air toxics in 2045. The modeled scenario had smaller
impacts on air toxic pollutants dominated by primary emissions (or a
decay product of a directly emitted pollutant), and relatively larger
impacts on air toxics that primarily result from photochemical
transformation, in this case due to the projected large reductions in
NOX emissions. Specifically, in 2045, our modeling projects
that ambient benzene and naphthalene concentrations will decrease by
less than 0.001 ug/m3 across the country. Acetaldehyde
concentrations will increase slightly across most of the country, while
formaldehyde will generally have small decreases in most areas and some
small increases in urban areas. Section 6.4.6 of the RIA contains more
detail on the impacts of the modeled scenario on air toxics
concentrations.
F. Visibility
Air quality modeling was used to project visibility conditions in
145 Mandatory Class I Federal areas across the United States. The
results show that the modeled scenario improved visibility in these
areas.\460\ The average visibility at all modeled Mandatory Class I
Federal areas on the 20 percent most impaired days is projected to
improve by 0.04 deciviews, or 0.37 percent, in 2045 due to the rule.
Section 6.4.7 of the RIA contains more detail on the visibility portion
of the air quality modeling.
---------------------------------------------------------------------------
\460\ The level of visibility impairment in an area is based on
the light-extinction coefficient and a unitless visibility index,
called a ``deciview'', which is used in the valuation of visibility.
The deciview metric provides a scale for perceived visual changes
over the entire range of conditions, from clear to hazy. Under many
scenic conditions, the average person can generally perceive a
change of one deciview. The higher the deciview value, the worse the
visibility. Thus, an improvement in visibility is a decrease in
deciview value.
---------------------------------------------------------------------------
G. Nitrogen Deposition
The scenario modeled for the proposed rule projected substantial
decreases in nitrogen deposition in 2045. The modeled scenario resulted
in annual decreases of greater than 4 percent in some areas and greater
than
[[Page 4422]]
1 percent over much of the rest of the country. For maps of deposition
impacts, and additional information on these impacts, see Section 6.4.8
of the RIA.
H. Environmental Justice
EPA's 2016 ``Technical Guidance for Assessing Environmental Justice
in Regulatory Analysis'' provides recommendations on conducting the
highest quality analysis feasible, recognizing that data limitations,
time and resource constraints, and analytic challenges will vary by
media and regulatory context.\461\ When assessing the potential for
disproportionately high and adverse health or environmental impacts of
regulatory actions on people of color, low-income populations, Tribes,
and/or indigenous peoples, the EPA strives to answer three broad
questions: (1) Is there evidence of potential environmental justice
(EJ) concerns in the baseline (the state of the world absent the
regulatory action)? Assessing the baseline will allow the EPA to
determine whether pre-existing disparities are associated with the
pollutant(s) under consideration (e.g., if the effects of the
pollutant(s) are more concentrated in some population groups). (2) Is
there evidence of potential EJ concerns for the regulatory option(s)
under consideration? Specifically, how are the pollutant(s) and its
effects distributed for the regulatory options under consideration?
And, (3) do the regulatory option(s) under consideration exacerbate or
mitigate EJ concerns relative to the baseline? It is not always
possible to quantitatively assess these questions.
---------------------------------------------------------------------------
\461\ ``Technical Guidance for Assessing Environmental Justice
in Regulatory Analysis.'' Epa.gov, Environmental Protection Agency,
https://www.epa.gov/sites/production/files/2016-06/documents/ejtg_5_6_16_v5.1.pdf. (June 2016).
---------------------------------------------------------------------------
EPA's 2016 Technical Guidance does not prescribe or recommend a
specific approach or methodology for conducting an environmental
justice analysis, though a key consideration is consistency with the
assumptions underlying other parts of the regulatory analysis when
evaluating the baseline and regulatory options. Where applicable and
practicable, the Agency endeavors to conduct such an analysis.\462\ EPA
is committed to conducting environmental justice analysis for
rulemakings based on a framework similar to what is outlined in EPA's
Technical Guidance, in addition to investigating ways to further weave
environmental justice into the fabric of the rulemaking process.
---------------------------------------------------------------------------
\462\ As described in this section, EPA evaluated environmental
justice for this rule as recommended by the EPA 2016 Technical
Guidance. However, it is EPA's assessment of the relevant statutory
factors in CAA section 202(a)(3)(A) that justify the final emission
standards. See section I.D. for further discussion of the statutory
authority for this rule.
---------------------------------------------------------------------------
There is evidence that communities with EJ concerns are
disproportionately impacted by the emissions sources controlled in this
final rule.\463\ Numerous studies have found that environmental hazards
such as air pollution are more prevalent in areas where people of color
and low-income populations represent a higher fraction of the
population compared with the general population.464 465 466
Consistent with this evidence, a recent study found that most
anthropogenic sources of PM2.5, including industrial sources
and light- and heavy-duty vehicle sources, disproportionately affect
people of color.\467\ In addition, compared to non-Hispanic Whites,
some other racial groups experience greater levels of health problems
during some life stages. For example, in 2018-2020, about 12 percent of
non-Hispanic Black; 9 percent of non-Hispanic American Indian/Alaska
Native; and 7 percent of Hispanic children were estimated to currently
have asthma, compared with 6 percent of non-Hispanic White
children.\468\ Nationally, on average, non-Hispanic Black and Non-
Hispanic American Indian or Alaska Native people also have lower than
average life expectancy based on 2019 data, the latest year for which
CDC estimates are available.\469\
---------------------------------------------------------------------------
\463\ Mohai, P.; Pellow, D.; Roberts Timmons, J. (2009)
Environmental justice. Annual Reviews 34: 405-430. https://doi.org/10.1146/annurev-environ-082508-094348.
\464\ Rowangould, G.M. (2013) A census of the near-roadway
population: public health and environmental justice considerations.
Trans Res D 25: 59-67. http://dx.doi.org/10.1016/j.trd.2013.08.003.
\465\ Marshall, J.D., Swor, K.R.; Nguyen, N.P. (2014)
Prioritizing environmental justice and equality: diesel emissions in
Southern California. Environ Sci Technol 48: 4063-4068. https://doi.org/10.1021/es405167f.
\466\ Marshall, J.D. (2008) Environmental inequality: air
pollution exposures in California's South Coast Air Basin. Atmos
Environ 21: 5499-5503. https://doi.org/10.1016/j.atmosenv.2008.02.005.
\467\ C.W. Tessum, D.A. Paolella, S.E. Chambliss, J.S. Apte,
J.D. Hill, J.D. Marshall, PM2.5 polluters
disproportionately and systemically affect people of color in the
United States. Sci. Adv. 7, eabf4491 (2021).
\468\ http://www.cdc.gov/asthma/most_recent_data.htm.
\469\ Arias, E. Xu, J. (2022) United States Life Tables, 2019.
National Vital Statistics Report, Volume 70, Number 19. [Online at
https://www.cdc.gov/nchs/data/nvsr/nvsr70/nvsr70-19.pdf].
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In addition, as discussed in Section II.B.7 of this document,
concentrations of many air pollutants are elevated near high-traffic
roadways, and populations who live, work, or go to school near high-
traffic roadways experience higher rates of numerous adverse health
effects, compared to populations far away from major roads.
EPA's analysis of environmental justice includes an examination of
the populations living in close proximity to truck routes and to major
roads more generally. This analysis, described in Section VII.H.1 of
this document, finds that there is substantial evidence that people who
live or attend school near major roadways are more likely to be people
of color, Hispanic ethnicity, and/or low socioeconomic status. This
final rule will reduce emissions that contribute to NO2 and
other near-roadway pollution, improving air quality for the 72 million
people who live near major truck routes and are already overburdened by
air pollution from diesel emissions.
Heavy-duty vehicles also contribute to regional concentrations of
ozone and PM2.5. As described in Section VII.H.2 of this
document, EPA used the air quality modeling data described in this
Section VII to conduct a demographic analysis of human exposure to
future air quality in scenarios with and without the rule in place.
Although the spatial resolution of the air quality modeling is not
sufficient to capture very local heterogeneity of human exposures,
particularly the pollution concentration gradients near roads, the
analysis does allow estimates of demographic trends at a national
scale. The analysis indicates that the largest predicted improvements
in both ozone and PM2.5 are estimated to occur in areas with
the worst baseline air quality, and that a larger number of people of
color are projected to reside in these areas.
1. Demographic Analysis of the Near-Road Population
We conducted an analysis of the populations living in close
proximity to truck freight routes as identified in USDOT's FAF4.\470\
FAF4 is a model from the USDOT's Bureau of Transportation Statistics
(BTS) and Federal Highway Administration (FHWA), which provides data
associated with freight movement in the United States.\471\ Relative to
the rest of
[[Page 4423]]
the population, people living near FAF4 truck routes are more likely to
be people of color and have lower incomes than the general population.
People living near FAF4 truck routes are also more likely to live in
metropolitan areas. Even controlling for region of the country, county
characteristics, population density, and household structure, race,
ethnicity, and income are significant determinants of whether someone
lives near a FAF4 truck route. We note that we did not analyze the
population living near warehousing, distribution centers,
transshipment, ot intermodal freight facilities.
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\470\ U.S. EPA (2021). Estimation of Population Size and
Demographic Characteristics among People Living Near Truck Routes in
the Conterminous United States. Memorandum to the Docket.
\471\ FAF4 includes data from the 2012 Commodity Flow Survey
(CFS), the Census Bureau on international trade, as well as data
associated with construction, agriculture, utilities, warehouses,
and other industries. FAF4 estimates the modal choices for moving
goods by trucks, trains, boats, and other types of freight modes. It
includes traffic assignments, including truck flows on a network of
truck routes. https://ops.fhwa.dot.gov/freight/freight_analysis/faf/
.
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We additionally analyzed national databases that allowed us to
evaluate whether homes and schools were located near a major road and
whether disparities in exposure may be occurring in these environments.
Until 2009, the U.S. Census Bureau's American Housing Survey (AHS)
included descriptive statistics of over 70,000 housing units across the
nation and asked about transportation infrastructure near respondents'
homes every two years.472 473 We also analyzed the U.S.
Department of Education's Common Core of Data (CCD), which includes
enrollment and location information for schools across the United
States.\474\
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\472\ U.S. Department of Housing and Urban Development, & U.S.
Census Bureau. (n.d.). Age of other residential buildings within 300
feet. In American Housing Survey for the United States: 2009 (pp. A-
1). Retrieved from https://www.census.gov/programs-surveys/ahs/data/2009/ahs-2009-summary-tables0/h150-09.html.
\473\ The 2013 AHS again included the ``etrans'' question about
highways, airports, and railroads within half a block of the housing
unit but has not maintained the question since then.
\474\ http://nces.ed.gov/ccd/.
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In analyzing the 2009 AHS, we focused on whether a housing unit was
located within 300 feet of a ``4-or-more lane highway, railroad, or
airport'' (this distance was used in the AHS analysis).\475\ We
analyzed whether there were differences between households in such
locations compared with those in locations farther from these
transportation facilities.\476\ We included other variables, such as
land use category, region of country, and housing type. We found that
homes with a non-White householder were 22-34 percent more likely to be
located within 300 feet of these large transportation facilities than
homes with White householders. Homes with a Hispanic householder were
17-33 percent more likely to be located within 300 feet of these large
transportation facilities than homes with non-Hispanic householders.
Households near large transportation facilities were, on average, lower
in income and educational attainment and more likely to be a rental
property and located in an urban area compared with households more
distant from transportation facilities.
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\475\ This variable primarily represents roadway proximity.
According to the Central Intelligence Agency's World Factbook, in
2010, the United States had 6,506,204 km of roadways, 224,792 km of
railways, and 15,079 airports. Highways thus represent the
overwhelming majority of transportation facilities described by this
factor in the AHS.
\476\ Bailey, C. (2011) Demographic and Social Patterns in
Housing Units Near Large Highways and other Transportation Sources.
Memorandum to docket.
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In examining schools near major roadways, we used the CCD from the
U.S. Department of Education, which includes information on all public
elementary and secondary schools and school districts nationwide.\477\
To determine school proximities to major roadways, we used a geographic
information system (GIS) to map each school and roadways based on the
U.S. Census's TIGER roadway file.\478\ We estimated that about 10
million students attend schools within 200 meters of major roads, about
20 percent of the total number of public school students in the United
States.\479\ About 800,000 students attend public schools within 200
meters of primary roads, or about 2 percent of the total. We found that
students of color were overrepresented at schools within 200 meters of
primary roadways, and schools within 200 meters of primary roadways had
a disproportionate population of students eligible for free or reduced-
price lunches.\480\ Black students represent 22 percent of students at
schools located within 200 meters of a primary road, compared to 17
percent of students in all U.S. schools. Hispanic students represent 30
percent of students at schools located within 200 meters of a primary
road, compared to 22 percent of students in all U.S. schools.
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\477\ http://nces.ed.gov/ccd/.
\478\ Pedde, M.; Bailey, C. (2011) Identification of Schools
within 200 Meters of U.S. Primary and Secondary Roads. Memorandum to
the docket.
\479\ Here, ``major roads'' refer to those TIGER classifies as
either ``Primary'' or ``Secondary.'' The Census Bureau describes
primary roads as ``generally divided limited-access highways within
the Federal interstate system or under state management.'' Secondary
roads are ``main arteries, usually in the U.S. highway, state
highway, or county highway system.''
\480\ For this analysis we analyzed a 200-meter distance based
on the understanding that roadways generally influence air quality
within a few hundred meters from the vicinity of heavily traveled
roadways or along corridors with significant trucking traffic. See
U.S. EPA, 2014. Near Roadway Air Pollution and Health: Frequently
Asked Questions. EPA-420-F-14-044.
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We also reviewed existing scholarly literature examining the
potential for disproportionate exposure among people of color and
people with low socioeconomic status (SES). Numerous studies evaluating
the demographics and socioeconomic status of populations or schools
near roadways have found that they include a greater percentage of
residents of color, as well as lower SES populations (as indicated by
variables such as median household income). Locations in these studies
include Los Angeles, CA; Seattle, WA; Wayne County, MI; Orange County,
FL; the State of California generally; and
nationally.481 482 483 484 485 486 487 Such disparities may
be due to multiple factors.488 489 490 491 492
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\481\ Marshall, J.D. (2008) Environmental inequality: air
pollution exposures in California's South Coast Air Basin.
\482\ Su, J.G.; Larson, T.; Gould, T.; Cohen, M.; Buzzelli, M.
(2010) Transboundary air pollution and environmental justice:
Vancouver and Seattle compared. GeoJournal 57: 595-608. doi:10.1007/
s10708-009-9269-6.
\483\ Chakraborty, J.; Zandbergen, P.A. (2007) Children at risk:
measuring racial/ethnic disparities in potential exposure to air
pollution at school and home. J Epidemiol Community Health 61: 1074-
1079. doi:10.1136/jech.2006.054130.
\484\ Green, R.S.; Smorodinsky, S.; Kim, J.J.; McLaughlin, R.;
Ostro, B. (20042004) Proximity of California public schools to busy
roads. Environ Health Perspect 112: 61-66. doi:10.1289/ehp.6566.
\485\ Wu, Y.; Batterman, S.A. (2006) Proximity of schools in
Detroit, Michigan to automobile and truck traffic. J Exposure Sci &
Environ Epidemiol. doi:10.1038/sj.jes.7500484.
\486\ Su, J.G.; Jerrett, M.; de Nazelle, A.; Wolch, J. (2011)
Does exposure to air pollution in urban parks have socioeconomic,
racial, or ethnic gradients? Environ Res 111: 319-328.
\487\ Jones, M.R.; Diez-Roux, A.; Hajat, A.; et al. (2014) Race/
ethnicity, residential segregation, and exposure to ambient air
pollution: The Multi-Ethnic Study of Atherosclerosis (MESA). Am J
Public Health 104: 2130-2137. [Online at: https://doi.org/10.2105/AJPH.2014.302135].
\488\ Depro, B.; Timmins, C. (2008) Mobility and environmental
equity: do housing choices determine exposure to air pollution? Duke
University Working Paper.
\489\ Rothstein, R. The Color of Law: A Forgotten History of How
Our Government Segregated America. New York: Liveright, 2018.
\490\ Lane, H.J.; Morello-Frosch, R.; Marshall, J.D.; Apte, J.S.
(2022) Historical redlining is associated with present-day air
pollution disparities in US Cities. Environ Sci & Technol Letters 9:
345-350. DOI: [Online at: https://doi.org/10.1021/acs.estlett.1c01012].
\491\ Ware, L. (2021) Plessy's legacy: the government's role in
the development and perpetuation of segregated neighborhoods. RSF:
The Russel Sage Foundation Journal of the Social Sciences, 7:92-109.
DOI: DOI: 10.7758/RSF.2021.7.1.06.
\492\ Archer, D.N. (2020) ``White Men's Roads through Black
Men's Homes'': advancing racial equity through highway
reconstruction. Vanderbilt Law Rev 73: 1259.
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People with low SES often live in neighborhoods with multiple
stressors
[[Page 4424]]
and health risk factors, including reduced health insurance coverage
rates, higher smoking and drug use rates, limited access to fresh food,
visible neighborhood violence, and elevated rates of obesity and some
diseases such as asthma, diabetes, and ischemic heart disease. Although
questions remain, several studies find stronger associations between
air pollution and health in locations with such chronic neighborhood
stress, suggesting that populations in these areas may be more
susceptible to the effects of air pollution.493 494 495 496
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\493\ Clougherty, J.E.; Kubzansky, L.D. (2009) A framework for
examining social stress and susceptibility to air pollution in
respiratory health. Environ Health Perspect 117: 1351-1358.
Doi:10.1289/ehp.0900612.
\494\ Clougherty, J.E.; Levy, J.I.; Kubzansky, L.D.; Ryan, P.B.;
Franco Suglia, S.; Jacobson Canner, M.; Wright, R.J. (2007)
Synergistic effects of traffic-related air pollution and exposure to
violence on urban asthma etiology. Environ Health Perspect 115:
1140-1146. doi:10.1289/ehp.9863.
\495\ Finkelstein, M.M.; Jerrett, M.; DeLuca, P.; Finkelstein,
N.; Verma, D.K.; Chapman, K.; Sears, M.R. (2003) Relation between
income, air pollution and mortality: a cohort study. Canadian Med
Assn J 169: 397-402.
\496\ Shankardass, K.; McConnell, R.; Jerrett, M.; Milam, J.;
Richardson, J.; Berhane, K. (2009) Parental stress increases the
effect of traffic-related air pollution on childhood asthma
incidence. Proc Natl Acad Sci 106: 12406-12411. doi:10.1073/
pnas.0812910106.
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Several publications report nationwide analyses that compare the
demographic patterns of people who do or do not live near major
roadways.497 498 499 500 501 502 Three of these studies
found that people living near major roadways are more likely to be
people of color or low in SES.503 504 505 They also found
that the outcomes of their analyses varied between regions