Revision of Tier 4 Criteria Pollutant
Standards, Part 1: Amendments to Phase-in
Schedule for Light-Duty and Medium-Duty
Vehicles
Draft Regulatory Impact Analysis
rnA United States
Environmental Protection
kl Agency
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Revision of Tier 4 Criteria Pollutant
Standards, Part 1: Amendments to
Phase-in Schedule for Light-Duty
and Medium-Duty Vehicles
Draft Regulatory Impact Analysis
Transportation Sector Impacts and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
United States
Environmental Protection
Lai M ^Agency
EPA-420-D-26-001
May 2026
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Table of Contents
List of Tables ii
List of Figures iii
Executive Summary iv
Chapter 1: Estimated Technology Cost Impacts 1-1
1.1 Costs Associated with the Tier 4 NMOG+NOX Standards 1-3
1.2 Costs Associated with the Tier 4 PM Standards 1-7
1.3 Total Costs Associated with the Proposed Rule 1-9
1.4 Sensitivity Analysis of Costs 1-10
Chapter 2: Emissions, Air Quality, and Health Impacts 2-1
2.1 Modeled Emissions Changes from the Proposed Rule 2-1
2.1.1 Action Case 2-2
2.1.2 Emission changes 2-3
2.2 Air Quality Impacts of the Proposed Rule 2-5
2.3 Health and Welfare Effects of Proposed Rule Related to Changes in Air Quality 2-6
2.3.1 Human Health Effects 2-12
2.3.2 Welfare Effects 2-14
Appendix to Chapter 2 2A-1
Chapter 3: Comparison of Benefits and Costs 3-1
3.1 Methods 3-1
3.2 Results 3-1
Chapter 4: Small Business Flexibilities 4-1
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List of Tables
Table ES-1: Estimated Cost Savings (millions of dollars (2024$)) iv
Table ES-2: Estimated Impacts on Emissions v
Table 1-1: Direct Manufacturing Catalyst Component Costs Estimates (2012$ and 2024$) (U.S.
EPA 2024) 1-4
Table 1-2: NMOG+NOx Fleet Average Emissions for Light-Duty Vehicles up to 6,000 lb.
GVWR in the Action and No-Action Cases 1-5
Table 1-3: Estimated 2027 Present Value of Per-Vehicle Cost Savings Associated with
NMOG+NOx Controls 1-6
Table 1-4: Estimated 2027 Present Value of Industry Cost Savings Associated with
NMOG+NOx Controls 1-7
Table 1-5: Estimated 2027 Present Value of Per-Vehicle Cost Savings Associated with PM
Controls 1-8
Table 1-6: Estimated 2027 Present Value of Industry Cost Savings Associated with PM Controls.
1-9
Table 1-7: Estimated 2027 Present Value of Industry Cost Savings Associated with
NMOG+NOx and PM Controls Combined 1-9
Table 1-8: Sensitivity Analysis: Estimated 2027 Present Value Range of Industry Cost Savings
Associated with NMOG+NOx Controls 1-10
Table 1-9: Sensitivity Analysis: Estimated 2027 Present Value Range of Industry Cost Savings
Associated with PM Controls 1-11
Table 1-10: Sensitivity Analysis: Estimated 2027 Present Value Range of Industry Cost Savings
Associated with NMOG+NOx and PM Controls Combined 1-11
Table 2-1: Weighted Light-Duty EV Populations Modeled in MOVES for All Scenarios 2-2
Table 2-2: Annual Increases in National Onroad Emissions for Criteria Pollutants and Air Toxics
in Select CYs for the Central Scenario 2-3
Table 2-3: Year-Over-Year Emissions Increases in NOx, VOC, and PM2.5 for Central Scenario.2-
5
Table 2-4: Health Effects of Ambient Ozone and PM2.5 2-7
Table 2A-1: Input LD EV Fractions Incorporated in MOVES for All Modeling Cases 2A-2
Table 2A-2: Year-Over-Year Emissions Increases in NOx, VOC, and PM2.5 for Sensitivity Cases.
2A-3
Table 2A-3: Year-Over-Year Emissions Increases in VOC, NOx and PM2.5 for Gasoline Cars,
Gasoline Trucks, and Diesel Vehicles for the Central Case 2A-4
Table 2A-4: Year-Over-Year Emissions Increases in VOC, NOx and PM2.5 for Gasoline Cars,
Gasoline Trucks, and Diesel Vehicles for the Low EV Case 2A-5
Table 2A-5: Year-Over-Year Emissions Increases in VOC, NOx and PM2.5 for Gasoline Cars,
Gasoline Trucks, and Diesel Vehicles for the High EV Case 2A-6
Table 2A-6: Year-Over-Year Emissions Increases for Select Air Toxics for Central Case 2A-7
Table 2A-7: Year-Over-Year Emissions Increases for Select Air Toxics for Low EV Case... 2A-8
Table 2A-8: Year-Over-Year Emissions Increases for Select Air Toxics for High EV Case. . 2A-9
Table 3-1: Costs and Benefits of the Proposal (millions, 2024$).a'd 3-2
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List of Figures
Figure 1-1: NMOG+NOx Certification Bins with Respect to Vehicle ETW (in lb.) for Vehicles
with GVWR up to 6,000 lb 1-1
Figure 2-1 Emissions Increases from No-Action Case Across the Range of Years and Scenarios
Modeled for PM2.5, NOx and VOC 2-4
Figure 2-2: Data Inputs and Outputs for the BenMAP-CE Model Using PM2.5 as an Example. 2-
9
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Executive Summary
This Draft Regulatory Impact Analysis (DRIA) contains supporting documentation for the
U.S. Environmental Protection Agency's (EPA) proposed rulemaking to amend the phase-in
schedule for the Tier 4 criteria pollutant standards for light-duty and medium-duty vehicles. This
proposed action has the potential to impact compliance costs for the manufacturers and importers
of light-duty vehicles. The DRIA also addresses requirements in Clean Air Act (CAA) section
317 and requirements under Executive Order (E.O.) 12866 to estimate the benefits and costs of
major new pollution control regulations. The preamble to the Federal Register notice associated
with this document provides the full context for the proposed rule, and it references this DRIA
throughout.
Summary of Emissions Changes, Costs, Benefits, and Net Benefits
The EPA prepared an analysis of the impacts of this proposal on emissions, costs, benefits,
and net benefits. Please refer to Chapter 1, Chapter 2, and Chapter 3 of this DRIA for more
detailed discussion of emissions, costs, benefits, and net benefits. With respect to costs, this
proposal projects a cost reduction to manufacturers of approximately $1.66 billion to $1.77
billion in present value terms (assuming a 7-percent or 3-percent discount rate, respectively;
2024 dollars), as shown in Table ES-1.
Table ES-1: Estimated Cost Savings (millions of dollars (2024$))
CY 2027
CY 2028
Present
Value, 3%
Present
Value, 7%
Annualized
Value, 3%c
Annualized
Value, 7%c
Cost Savings for PM
Control
$220
$510
$690
$650
$36
$53
Cost Savings for
NMOG+NOx
Control
$470
$660
$1,070
$1,010
$56
$82
Sum of Cost Savings
$690
$1,170
$1,770
$1,660
$92
$135
This proposed rule estimates the emissions changes that would occur from implementation of
the proposed rule in model years (MYs) 2027 and 2028. The EPA estimated emissions impacts
based on what the emissions would have been had the Tier 4 program phase-in schedule not been
amended. Although the analysis assumes emissions would only change for MY 2027 and MY
2028 vehicles, those emission impacts would continue throughout the lifetime of the vehicles.
Therefore, the EPA estimated the annual lifetime emission impacts of the MYs 2027 and 2028
vehicles through calendar year (CY) 2055.
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Table ES-2 shows the estimated emissions impacts on volatile organic compounds (VOCs),
oxides of nitrogen (NOx), and particulate matter of 2.5 micrometers or less (PM2.5) occurring in
CYs 2027, 2028, and 2055, with positive values reflecting emission increases.
Table ES-2: Estimated Impacts on Emissions
Calendar Year
voc
NOx
PM2.5
Increase
Increase
Increase
(short tons)
(short tons)
(short tons)
2027
353
389
51
2028
859
976
145
2055
92
106
27
Finally, the emissions changes described above would also be associated with impacts to air
quality and human health. As discussed in section III.E of the preamble, the EPA did not
monetize the health effects associated with emissions changes. The net benefits associated with
this proposal are therefore the cost savings presented in Table ES-1. A qualitative description of
the human health and welfare effects related to emissions changes associated with this proposal
is provided in Chapter 2.3 of this DRIA.
There are likely to be sources of uncertainty in any complex analysis using estimated
parameters and inputs from numerous models and assumptions. These uncertainties may impact
both the baseline and the post-rule analysis, thus possibly affecting the estimated incremental
impacts of the proposed rulemaking. In this analysis, the EPA considered several sources of
uncertainty, both quantitatively and qualitatively, related to the costs and benefits of this action.
Information on uncertainty related to costs, including estimates of battery electric vehicle (BEV)
market share and variations in catalyst precious metal loading, can be found in Chapter 1 of this
DRIA, including sensitivity analysis. Information on uncertainty related to benefits, including the
quantification and monetization of health and welfare effects, can be found in section III.E of the
preamble and Chapter 3 of this DRIA.
DRIA Chapter Summary
This document contains the following Chapters:
Chapter 1: Estimated Technology Cost Impacts
This chapter provides estimates of the impacts of the proposal on vehicle technologies and the
cost of compliance.
Chapter 2: Emissions, Air Quality and Health Impacts
This chapter provides estimates of the impact of this proposal on highway vehicle emissions
of criteria pollutants, criteria pollutant precursors, and selected air toxics using an updated
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version of the EPA's Motor Vehicle Emission Simulator (MOVES5). The air quality impacts and
health effects are also discussed in this chapter.
Chapter 3: Costs and Benefits
This chapter summarizes the results of an analysis of costs and benefits for the proposal.
Chapter 4: Small Business Flexibilities
This chapter provides an analysis of the potential impacts of the proposal on small entities and
small volume manufacturers.
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Chapter 1: Estimated Technology Cost Impacts
In this DRIA, the EPA considers costs to the manufacturers, in particular, the hardware costs
associated with emissions control technologies for NMOG+NOx and PM. Because of the nature
of this proposed action and its projected effects on vehicles, the EPA examines the incremental
variable hardware costs associated with the various technologies. The EPA also projects changes
in fixed costs as discussed later in this Chapter. The EPA assumes that certain fixed costs, such
as those associated with certification, will be essentially unchanged because of this action and
are not considered further.
The EPA evaluated the emissions certification levels for light-duty vehicles up to 6,000
pounds gross vehicle weight rating (GVWR) across several recent MYs. As shown in Figure 1-1,
the EPA finds no correlation between a vehicle's estimated test weight (ETW, in pounds (lb.))
and the NMOG+NOx certification bin (in milligrams/mile (mg/mile)). This result suggests that
the costs for the technologies needed for Tier 4 emissions compliance could come from any
vehicle within the GVWR range and not just the largest or smallest.
180
160
140
a MY2022
x MY2023
¦ MY2024
~ MY2025
* MY2026
1 X X X
E 120 - —Bin30
x mummm&m m u u x x
c
CQ
o 100
a 80
u
x
O
+ 60
(J
O
¦¦¦¦««¦ m m
40
20
0
30 mg/mi. Fleet Average
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
Estimated Test Weight, ETW (lb.)
Figure 1-1: NMOG+NOx Certification Bins with Respect to Vehicle ETW (in lb.) for
Vehicles with GVWR up to 6,000 lb.
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For the cost analysis of this proposed rule, the EPA assumed that the annual sales volume of
all light-duty vehicles will be between 15 and 16 million units in both MY 2027 and MY 2028
for both the action and no-action cases.1 This assumption is based on sales data from recent years
and sales projections from the Annual Energy Outlook 2025 (AEO2025) and other groups (U.S.
EIA 2025), (Alliance for Automotive Innovation 2025). For those light-duty vehicles up to 6,000
pounds, the sales volume is estimated to be about 10.2 million units, including BEVs, which is
based on fleet compliance data submitted to the EPA covering MYs 2024 through 2026. Note
that the EPA has assumed that sales volumes remain the same in the action and no-action cases,
although if the cost savings to manufacturers resulted in lower vehicle prices the Agency would
expect vehicle sales to increase.
For the analysis for this proposal, the EPA used a projected BEV market share in MYs 2027
and 2028 (U.S. EPA 2026). These values are eight percent in MY 2027 and 12 percent in MY
2028 for all light-duty vehicles. These projected BEV market shares were developed using the
EPA OMEGA model. Details on the modeled projections can be found in an EPA technical
memorandum (U.S. EPA 2026). These market share values are consistent with sales figures from
the Alliance for Automotive Innovation and the EPA's own certification data over the last three
years. This share also applies to the subset of vehicles weighing up to 6,000 pounds GVWR, as
discussed in section III.A of the preamble. The EPA assumed the same number of BEVs would
be sold in MYs 2027 and 2028 in the no-action and the action case for the cost and emission
impact projections for this proposal. The EPA also conducted a sensitivity analysis, discussed in
detail in Chapter 1.4 of this DRIA, around these central values by increasing or decreasing them
by four percentage points. Thus, the full assessment considers four, eight, and 12 percent BEVs
in MY 2027 and eight, 12, and 16 percent in MY 2028.
The EPA assumes the cost differences between the action and no-action cases come from
changes to the emissions control technologies applied to internal combustion engine (ICE)
vehicles. The EPA recognizes that multiple potential compliance pathways exist, including those
that may rely more or less heavily on the use of BEVs than assumed in this proposal, and that the
actual costs of the proposal may differ from what the Agency estimates here.
For the cost analysis presented in this chapter, the EPA estimated the sales-weighted fleet
average emissions of NMOG+NOx from ICE vehicles after considering the BEV market share of
all light-duty vehicles up to 6,000 pounds GVWR. The EPA's assumption for the no-action case
is that light-duty vehicles up to 6,000 pounds GVWR will meet the Tier 3 fleet-average standard
of 30 mg/mile in MY 2026 and that manufacturers would add the technology needed to meet the
Tier 4 fleet-average NMOG+NOx standards of 25 and 23 mg/mile in MYs 2027 and 2028,
respectively. The EPA also chose to exclude the potential effects of the NMOG+NOx banking
and trading program from the cost assessment for this proposal. The EPA has seen little trading
of NMOG+NOx credits between companies during the Tier 3 program, and the Agency does not
have sufficient information to project how companies who have banked credits may use those
credits in MYs 2027 and 2028. The EPA chose to omit potential other cost categories, such as
effects on vehicle insurance costs, from this analysis because of the limited nature of this
proposal. In addition, the EPA's cost analysis only looks at costs or savings in MYs 2027 and
1 The action case represents the scenario in which the proposed changes to the regulations are implemented. The no-
action case represents the 'business as usual' scenario, in which this proposal is not included.
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2028 as they are the two MYs directly affected by this proposed action. However, future MYs
may also be affected due manufacturers' use of the banking and trading program.
In the existing Tier 4 standards, the default Tier 4 program for heavier light-duty vehicles
with GVWR between 6,001 and 8,500 pounds is that the NMOG+NOx fleet average stays at 30
mg/mile through MY 2029 and then drops to a 15 mg/mile fleet average in MY 2030. The
default Tier 4 program compliance schedule for medium-duty vehicles (MDVs), which are
between 8,501 and 14,000 pounds GVWR, does not require compliance with the Tier 4 program
until MY 2031. Thus, these heavier light-duty vehicles and the MDVs already have a compliance
schedule that does not require meeting the Tier 4 standards in either MY 2027 or MY 2028. The
EPA therefore focused the Agency's assessment of changes in costs and other impacts on those
vehicles up to 6,000 lbs. GVWR.
For the tailpipe PM standards in the no-action case, light-duty vehicles up to 6,000 pounds
GVWR are expected to follow the Tier 4 phase-in schedule from the 2024 LMDV Multipollutant
Rule. Thus, for the cost analysis presented here, the EPA considered the costs associated with
PM controls, including gasoline particulate filters (GPFs) and fuel injection systems, for that part
of the new light-duty vehicle fleet.
The EPA notes the emissions control technologies considered in this proposal for MYs 2027
and 2028 are already in volume production, therefore the Agency has not performed a detailed
feasibility assessment of these technologies. As discussed in the preamble for this proposal, the
EPA is proposing to extend the Tier 3 program and delay the start of the Tier 4 program for two
MYs due to concerns with lead time for vehicle development, not due to concerns with the
ability of technologies to achieve the MY 2027 and 2028 Tier 4 standards given sufficient lead
time.
In addition, the cost analysis described in this chapter for the proposed rule assumes that all
vehicle models that might have been certified to the final Tier 4 standards would instead be
certified to the interim Tier 4 or Tier 3 standards. The EPA is aware that some manufacturers
have already certified some vehicle models to the final Tier 4 standards for MY 2027, therefore
they may not realize the full level of cost savings estimated in this chapter. Thus, the cost savings
estimated in this chapter represent an upper bound. The Tier 4 program uses sales to determine
compliance with the per-vehicle standards and the NMOG+NOx fleet average standards and for
MYs 2027 and 2028 the Tier 4 PM standard is phased-in as a percentage of sales. The final
MY2027 sales data will not be submitted to EPA until calendar year 2028. EPA may include
additional information on this topic for the final rule analysis as we gather more information
regarding MY 2027 certifications.
1.1 Costs Associated with the Tier 4 NMOG+NOX Standards
There are many technology options for improving NMOG+NOx emissions, as the EPA
discussed in Chapter 3.2.5.1 of the 2024 LMDV Multipollutant Rule Regulatory Impact Analysis
("2024 LMDV RIA") (U.S. EPA 2024). Some of these technologies accelerate three-way catalyst
(TWC) system warm-up during the cold start of the FTP-75 cycle, while others help reduce
tailpipe emissions during operation once the exhaust aftertreatment system is warm. The
modeling performed for the 2024 LMDV RIA found that vehicle electrification to be the main
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compliance approach for achieving compliance with the combined GHG and Tier 4
NMOG+NOx emissions standards. Therefore, the 2024 LMDV RIA did not model the adoption
of specific NMOG+NOx emissions control technology for ICE vehicles.
For this cost analysis, the EPA has assumed that a likely pathway for Tier 4 NMOG+NOx
emissions compliance will be adding catalyst content to the TWCs on gasoline-fueled light-duty
program vehicles (U.S. EPA 2024). The application and steady improvement of TWCs for light-
duty program vehicles has been the most common approach to reducing NMOG and NOx
emissions from gasoline vehicles for nearly 50 years. Improvements in TWCs were the primary
technology automotive companies used to achieve the EPA Tier 2 and Tier 3 emission standards,
and TWCs are one of the technologies the Agency projected could be used to comply with the
Tier 4 NMOG+NOx standards. In addition, this pathway is straightforward to assess from a cost
perspective, since it relies upon adjusting the variable hardware cost associated with the TWC
catalyst loading.2
In the 2024 LMDV RIA, the EPA used the formulae presented in Table 1-1 for estimating the
costs associated with a TWC substrate, washcoat, and canning (U.S. EPA 2024). In addition to
the 2012$ costs presented in the LMDV RIA, the EPA also updated the parameters so that they
represent 2024$ (U.S. BLS 2025). Consistent with the EPA's approach in the 2024 LMDV RIA
and in past EPA rulemakings, the values in Table 1-1 are multiplied by a markup factor of 1.5 to
represent both the indirect and direct costs to the manufacturer (Rogozhin, et al. 2010).3
Table 1-1: Direct Manufacturing Catalyst Component Costs Estimates (2012$ and 2024$)
(U.S. EPA 2024).
Component
Cost equation (2012$)
Cost equation (2024$)
Catalyst substrate
$6.108xFtwCxVol+$1.955
$8,373 xFtwCxVol+$2.680
Catalyst washcoat
$5.09xFtwcxVol
$6.978xFtwcxVol
Catalyst canning
$2.4432xFtwcxVol
$3.3494xFtwcxVol
Note: Vol = engine displacement and Ftwc = TWC volume / engine displacement = 1.2
Source: SAE 2013-01-0534
Roughly 90 percent of the cost of a TWC is from the catalysts loaded into the catalyst
washcoat that facilitate pollutant removal from the exhaust gas. These catalysts are the precious
metals platinum (Pt), palladium (Pd), and rhodium (Rh), which are collectively known as
platinum group metals (PGM). To fully estimate the catalyst costs, one must know the loadings
of the three main elements in the TWC. Recent prices for these metals (Umicore 2025) are as
follows:
• Pt: $1,078.96 per troy ounce (oz.t.) or $34,689 per gram.
2 Manufacturers may determine that improved engines, controls, or other technologies may be a more cost-effective
pathway to lower tailpipe emissions, which introduces a potential source of uncertainty in the cost analysis here.
3 Indirect costs include warranty, research and development, production depreciation and amortization, corporate
operations (e.g., salaries, pensions, health care costs for corporate staff), OEM selling costs, dealer costs, and profit.
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• Pd: $1,058.99 per oz.t. or $34,047 per gram.
• Rh: $5,251.90 per oz.t. or $168,852 per gram.
These metal prices were adjusted to 2024$ for consistency with the rest of the cost analysis
presented here. Then these values were averaged over the two years prior to retrieval—
November 2, 2023, through November 2, 2025—to help smooth out fluctuations in the prices of
these commodities. As with the other elements of the TWC, these catalyst costs are further
multiplied by a markup factor of 1.5 to account for indirect costs at the vehicle manufacturer
level.
As discussed above, the main cost increases for Tier 4 NMOG+NOx controls for vehicles up
to 6,000 pounds GVWR are assumed to be from increases in TWC catalyst loadings to meet the
lower NMOG+NOx sales-weighted fleet averages in MYs 2027 and 2028. Thus, the expected
savings from the action case are from the incremental increase in PGM catalyst loading needed
for Tier 4 compliance that will not be needed under this proposed action. The EPA assumed that
the TWC system volume would be unchanged for a given engine displacement. The EPA also
projected the change in fleet average NMOG+NOx levels for new light-duty ICE vehicles. This
projection assumed fleet-wide compliance with the applicable standards for the action and no-
action cases given the BEV market share in the cost analysis. These values are shown in
Table 1-2, where the analysis uses the BEV market share projections discussed earlier in this
Chapter and in the preamble. The levels for ICE vehicles in the rightmost columns of Table 1-2
represent what the fleet average for the ICE vehicles needs to be so that, when averaged with the
zero mg/mile levels from the market share of BEVs, the overall total meets the "action" or "no-
action" regulatory standards, as shown in the second and third columns in the table.
Table 1-2: NMOG+NOx Fleet Average Emissions for Light-Duty Vehicles up to 6,000 lb.
GVWR in the Action and No-Action Cases.
Level for Light-Duty Vehicle Fleet
ICE Vehicle
Level for ICE Vehicles Only
(including BEVs)
market share
Model
Action Case No-Action Case
Action Case
No-Action Case
Year
(Tier 3) (mg/mi.) (Tier 4) (mg/mi.)
(mg/mi.)
(mg/mi.)
2027
30 25
92%
32.6
27.2
2028
30 23
88%
34.1
26.1
The estimated fleet average NMOG+NOx emissions levels for ICE light-duty vehicles up to
6,000 pounds are higher for the action case than for the no-action case. Thus, there is an expected
incremental savings in catalyst content in TWCs across all new light-duty vehicles in each MY.
For this cost analysis, sales of light-duty vehicles with ICEs are expected to be about 9.38
million vehicles in MY 2027 and 8.97 million in MY 2028.4 The EPA used Confidential
Business Information (CBI) from eight light-duty vehicle models, all but one of which were
light-duty vehicles up to 6,000 pounds GVWR. The exception was just over 6,000 pounds. The
EPA determined that improving emissions performance by one Tier 3 bin, e.g., Tier 3 Bin 50 to
4 With a ±4 percent range on the BEV market share, the range of expected sales of ICE vehicles are 8.97 million to
9.79 million in MY 2027 and 8.56 million to 9.38 million in MY 2028.
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Bin 30, would require adding about 2.5 to 4.7 g of Pd or Pt per vehicle to the TWC. The PGM
constituent, Rh, is assumed to stay the same. Pd and Pt are roughly interchangeable in TWC
catalyst formulations, since they serve a similar function, so the cost analysis would be
approximately the same using Pt costs instead of Pd costs as we have done here. Using the
average value of 3.6 g of Pd increases the TWC cost by about $175 per vehicle that improves
one bin, including the indirect cost markup factor of 1.5. The lower Pd content would also make
a replacement TWC cheaper, thus lowering maintenance costs over the life of the vehicle.
In MY 2027, the proposed fleet average NMOG+NOx emissions level for ICE light-duty
vehicles is 5.4 mg/mile higher in the action case than in the no-action case. The average vehicle
does not need to improve one full bin, that is, 20 mg/mile. The catalyst content is therefore pro-
rated by the average change in emissions level. For example, in MY 2027, the average
incremental Pd saved per vehicle is 3.6 g x (5.4 mg/mile / 20 mg/mile) = 0.98 g Pd, which has a
present value of $50 per vehicle (2024$), including markup. The CBI data suggest that the range
of catalyst content reduction is 2.5 to 4.7 g Pd per bin, thus the per-vehicle catalyst savings
would be $35 to $65, as shown in Table 1-3. The range in values in Table 1-3 reflects the range
of reduction in Pd loading. Similarly, for MY 2028 the emissions level is 7.7 mg/mile higher
than in the no-action case, which leads to a savings of about $51 to $95 per vehicle, again
depending on Pd loading. For MY 2028, the average savings increases to $73 per vehicle
(2024$) because the change is larger, i.e., the incremental Pd saved is 3.6 g x (8.0 / 20) = 1.43 g.
The per-vehicle cost savings estimates associated with the catalyst savings shown in Table 1-3
include undiscounted present values (in 2024$) and discounted present values using 3-percent
and 7-percent discount rates. The minimum per-vehicle values result from the lowest change in
Pd used, whereas the maximum per-vehicle values result from the highest change in Pd. Here,
the estimated change in Pd ranges from 0.69 g to 1.27 g in MY 2027 and from 1.00 to 1.86 g in
MY 2028. For the cost analyses, though, we have used the average change in Pd, which is 0.98 g
($50) in MY 2027 and 1.43 g ($73) in MY 2028.
Table 1-3: Estimated 2027 Present Value of Per-Vehicle Cost Savings Associated with
NMOG+NOx Controls.
Model
Cost Savings,
Cost Savings with 3%
Cost Savings with 7%
Year
undiscounted (2024$)
discount (2024$)
discount (2024$)
2027
$35-$65
$34 - $63
$33-$61
2028
$51-$95
$48 - $90
$45 - $84
Overall
$35-$95
$34 - $90
$33-$84
The overall estimated savings for all new light-duty vehicles up to 6,000 pounds are shown in
Table 1-4 for the central analysis case. The undiscounted present value of savings is shown along
with savings reflecting a 3-percent or 7-percent discount rate. The discounted present value of
the cost savings is discounted back to 2027 and uses year 2024 dollars. The projected
undiscounted savings for the average incremental Pd amount of 3.6 g is $470 million in MY
2027 and $660 million in MY 2028 (year 2024 dollars). With a 7-percent or 3-percent discount
rate, the average savings are $440 to $450 million in MY 2027 and $570 to $620 million in MY
2028 (year 2024 dollars).
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Table 1-4: Estimated 2027 Present Value of Industry Cost Savings Associated with
NMOG+NOx Controls.
Model
Year
ICE Vehicles
< 6,000 lb. GVWR
Cost Savings,
undiscounted (millions
of dollars (2024$))
Cost Savings with 3%
discount (millions of
dollars (2024$))
Cost Savings with 7%
discount (millions of
dollars (2024$))
2027
9.38 million
$470
$450
$440
2028
8.97 million
$660
$620
$570
Total
19.34 million
$1,120
$1,070
$1,010
As noted above, the 2024 LMDV RIA demonstrated compliance with the Tier 4 emissions
standards through vehicle electrification rather than the adoption of specific NMOG+NOx
emissions control technology for ICE vehicles. Since the cost estimates from the 2024 LMDV
RIA focused on vehicle electrification, the costs of meeting the now binding NMOG+NOx
standards on final Tier 4 ICE vehicles have not been accounted for separately. This modeling
limitation means that the cost savings for the NMOG+NOx portion of this rulemaking have
already been implicitly accounted for in a previous rulemaking. For this proposed rule, EPA is
providing explicit estimates of the compliance cost savings from delaying NMOG+NOx
standards by using the more realistic assumption that the NMOG+NOx standards would be met
by improvements in ICE vehicle technologies. In particular, we model compliance through ICE
vehicle catalyst improvements which cost less than complying through additional BEV sales.
1.2 Costs Associated with the Tier 4 PM Standards
The tailpipe PM emissions standards for Tier 4 from the 2024 LMDV Multipollutant Rule are
a per-vehicle standard of 0.5 mg/mile. This standard must be met on each of three laboratory test
cycles: -7°C ambient FTP-75, 25°C ambient FTP-75, and 25°C ambient US06. The PM standard
is a per-vehicle requirement and not a fleet average, therefore the cost savings are directly related
to the number of vehicles that need to meet the Tier 4 PM standard under the no-action case.
The Tier 4 standards are technology neutral, meaning that manufacturers may employ any
technology or combination of technologies to meet the PM standard. For purposes of this cost
analysis, though, the EPA has assumed that a GPF would be a cost-effective method to achieve
the standard because it is a technology that is already in production and familiar to
manufacturers.
The cost analysis of GPFs in Chapter 2.6.1.1.3 of the 2024 LMDV RIA (U.S. EPA 2024) used
the following formula:
GPF = (42.269 x Vol + 22.213) x Markup
where Vol = the engine displacement in liters and Markup = the markup to include indirect
costs, which was 1.5 in the 2024 LMDV RIA. To adjust the cost estimate from 2022$ to 2024$
(U.S. BLS 2025), the multiplicative cost factor should be 44.817 and the additive, 23.882,
leading to a revised formula of
GPF = (44.817 x Vol + 23.882) x Markup
For example, if a vehicle had an engine displacement of 2.13 liters, which is the sales-weighted
average for vehicles up to 6,000 pounds, the EPA would expect the cost to the manufacturer to
be (44.817 x 2.13 + 23.882) x 1.5 = $179 (2024$). The engine displacements for these vehicles
1-7
-------
range from 1.5 liters to 5.0 liters, which yields a GPF cost range of $137 to $372 per vehicle as
shown in Table 1-5. This range in engine displacements represents a potential source of
uncertainty in the cost savings estimates. Discounted present values are also included using the
3-percent and 7-percent discount rates.
Table 1-5: Estimated 2027 Present Value of Per-Vehicle Cost Savings Associated with PM
Controls.
Model
Cost Savings,
Cost Savings with 3%
Cost Savings with 7%
Year
undiscounted (2024$)
discount (2024$)
discount (2024$)
2027
$137-$372
$133-$361
$128-$348
2028
$137-$372
$129-$351
$119-$325
Total
$137-$372
$129-$361
$119-$348
Currently, many manufacturers manage tailpipe PM emissions to the Tier 3 standard of 3
mg/mile by using a fuel injection system that combines a direct injection (DI) system with a port
fuel injection (PFI) system. This combination allows the engine to achieve the efficiency benefits
of the DI system at most operating points while mitigating engine-out PM emissions at high load
by using the PFI system. There is a potential cost savings when fitting a GPF for manufacturers
to simplify their fuel injection system by removing the PFI injectors. However, the EPA knows
that not all manufacturers use a dual-injector approach currently, and there may be other
engineering reasons to retain a dual system even with a GPF. Therefore, the cost analysis
assumes no change in the number of PFI injectors and the projected net cost savings accounts for
the savings associated with removing the GPF only. This assumption will tend to overstate the
savings for those manufacturers who chose to remove the PFI injectors when fitting the GPF,
since the PFI system cost will offset the GPF savings.
The incremental cost savings applies to each vehicle with a GVWR up to 6,000 pounds that
needs to meet Tier 4 in the current phase-in schedule {i.e., the no-action case) that would instead
be at Tier 3 under this proposed action. The number of vehicles affected and the range of
potential savings over the two MYs is shown in Table 1-6, where the savings reflect a 3-percent
or 7-percent discount rate. The number of vehicles affected increases from approximately 1.22
million in MY 2027 to approximately 2.85 million in MY 2028, which are 12 percent and 28
percent of the vehicles with a GVWR up to 6,000 pounds, respectively. Note that the affected
number of vehicles for PM controls is less than for NMOG+NOx because the PM standards are
per-vehicle standards while the NMOG+NOx standards are fleet average standards. In MY 2027
under the current Tier 4 program, 20 percent of new vehicles must meet the 0.5 mg/mile PM
standard, whereas a manufacturers' MY 2027 fleet must collectively meet the 25 mg/mile
NMOG+NOx standard.
The cost savings shown in Table 1-6 use the sales-weighted average engine displacement and
the number of vehicles that would need GPFs in the central no-action case. The sales-weighted
average engine displacement in vehicles up to 6,000 pounds GVWR is 2.13 liters, where the full
range is 1.5 to 5.0 liters in these vehicles.
1-8
-------
Table 1-6: Estimated 2027 Present Value of Industry Cost Savings Associated with PM
Controls.
Model
Year
Tier 4 ICE
Vehicles < 6,000
lb. GVWR
Cost Savings,
undiscounted (millions
of dollars (2024$))
Cost Savings with 3%
discount (millions of
dollars (2024$))
Cost Savings with 7%
discount (millions of
dollars (2024$))
2027
1.22 million
$220
$210
$200
2028
2.85 million
$510
$480
$450
Total
4.08 million
$730
$690
$650
1.3 Total Costs Associated with the Proposed Rule
The combination of savings in NMOG+NOx controls and PM controls will be substantial for
manufacturers, both on a per-vehicle basis and overall. As described in Chapters 1.1 and 1.2, the
per-vehicle costs for this proposed rule apply to significantly different numbers of vehicles. The
market share of BEVs in the central action case is projected to be 8 percent, or about 815,000
vehicles, in MY 2027 and 12 percent, or 1.22 million vehicles, in MY 2028 (U.S. EPA 2026).
The cost savings for the two technologies apply to different numbers of vehicles. The
NMOG+NOx standards apply to all light-duty program vehicles up to 6,000 pounds GVWR
because they use a sales-weighted fleet average. With the projected market share of BEVs, this
means that the NMOG+NOx controls apply to 9.38 million vehicles in MY 2027 and 8.97
million vehicles in MY 2028.
By contrast, the PM standards are a per-vehicle standard, so the costs are only incurred on
those vehicles that will need a GPF to mitigate PM emissions. This means 20 percent of light-
duty program vehicles up to 6,000 pounds GVWR will need to meet or exceed Tier 4 PM
emissions in MY 2027, and 40 percent in MY 2028. With the projected BEV market shares in
these two MYs, 1.22 million vehicles will need GPFs in MY 2027 and 2.85 million in MY 2028.
The full cost savings estimate is therefore calculated by combining the savings from
NMOG+NOx controls and PM controls. The combined savings using undiscounted values and
with both discount rates are shown in Table 1-7. The middle estimates of undiscounted cost
savings in the range are expected to be $1.85 billion. The present value of cost savings is $1.77
billion assuming a 3-percent discount rate and $1.66 billion assuming a 7-percent discount rate
(all in year 2024 dollars).
Table 1-7: Estimated 2027 Present Value of Industry Cost Savings Associated with
NMOG+NOx and PM Controls Combined.
Model
Year
Cost Savings,
undiscounted (millions of
dollars (2024$))
Cost Savings with 3%
discount (millions of
dollars (2024$))
Cost Savings with 7%
discount (millions of
dollars (2024$))
2027
$690
$670
$640
2028
$1,170
$1,100
$1,020
Total
$1,850
$1,770
$1,660
1-9
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1.4 Sensitivity Analysis of Costs
The results presented in the preceding part of Chapter 1 are focused on the central analysis
case, where the market share of BEVs is projected to be 8 percent in MY 2027 and 12 percent in
MY 2028. There are two main sources of variability in the estimated cost savings are variability
in the market share of BEVs sold in MYs 2027 and 2028, and variability in per-vehicle costs.
For the first point, the EPA assumed that the BEV market share might vary by four percentage
points in each MY. Thus, in MY 2027, the market share could be 4 percent to 12 percent BEVs,
or 408,000 to 1,220,000 BEVs sold. Likewise, in MY 2028, the market share could be 8 percent
to 16 percent BEVs, or 815,000 to 1,630,000 BEVs sold. This range in BEV market share affects
the number of vehicles needing more catalyst to control NMOG+NOx emissions and the number
of vehicles needing GPFs to control PM emissions.
Therefore, for the NMOG+NOx standards, the range is 8.97 million to 9.79 million vehicles
in MY 2027 and 8.56 million to 9.38 million vehicles in MY 2028 because the NMOG+NOx
standards apply to all vehicles sold. By contrast, the PM standards only apply to the portion of
new vehicles sold that must comply with final Tier 4 standards, which is 815,000 to 1,630,000
vehicles in MY 2027 and 2.45 million to 3.26 million vehicles in MY 2028.
For the second point, CBI shows that the TWC catalyst loading has significant vehicle to
vehicle variability within a given certification bin. The Pd loadings are a complex function of
catalyst dispersion within the washcoat, other washcoat compounds that stabilize the catalyst, the
geometry of the TWC system, TWC warm-up strategy, and engine-out emissions levels.
The estimated range of cost savings associated with NMOG+NOx controls therefore includes
the effects of BEV market share variability and the range of Pd loadings in light-duty program
vehicles observed in the CBI. These cost savings results are shown in Table 1-8 for undiscounted
present values and also values discounted by 3-percent or 7-percent.
Table 1-8: Sensitivity Analysis: Estimated 2027 Present Value Range of Industry Cost
Savings Associated with NMOG+NOx Controls.
Model
ICE Vehicles
Cost Savings,
Cost Savings with 3%
Cost Savings with 7%
Year
< 6,000 lb. GVWR
undiscounted (millions
discount (millions of
discount (millions of
(million)
of dollars (2024$))
dollars (2024$))
dollars (2024$))
2027
8.97-9.79
$330-$610
$320 - $590
$310-$570
2028
8.56-9.38
$440 - $850
$430 - $800
$400 - $740
Total
17.53-19.16
$790 - $1,460
$750-$1,390
$710-$1,310
The estimated range of cost savings associated with PM controls includes the effects of BEV
market share variability and light-duty program vehicle variability, including engine
displacements. These cost savings results are shown in Table 1-9 for undiscounted present values
and also values discounted by 3 percent or 7 percent.
1-10
-------
Table 1-9: Sensitivity Analysis: Estimated 2027 Present Value Range of Industry Cost
Savings Associated with PM Controls.
Model
Tier 4 ICE
Cost Savings,
Cost Savings with 3%
Cost Savings with 7%
Year
Vehicles < 6,000 lb.
undiscounted (millions
discount (millions of
discount (millions of
GVWR (million)
of dollars (2024$))
dollars (2024$))
dollars (2024$))
2027
0.82-1.63
$150-$290
$140-$280
$140-$270
2028
2.45-3.26
$440 - $580
$410-$550
$380-$510
Total
3.26-1.89
$580 - $880
$550-$830
$520 - $780
The results in Tables 1-8 and 1-9 can be combined to show the overall estimated range of cost
savings to industry, as shown in Table 1-10.
Table 1-10: Sensitivity Analysis: Estimated 2027 Present Value Range of Industry Cost
Savings Associated with NMOG+NOx and PM Controls Combined.
Model
Cost Savings,
Cost Savings with 3%
Cost Savings with 7%
Year
undiscounted (millions of
discount (millions of
discount (millions of
dollars (2024$))
dollars (2024$))
dollars (2024$))
2027
$470 - $900
$460 - $870
$440 - $840
2028
$900-$1,430
$850-$1,350
$780-$1,250
Total
$1,370-$2,330
$1,310-$2,230
$1,230-$2,090
1-11
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References
91 FR7686. 2026. (February 18). https://www.govinfo.gov/content/pkg/FR-2026-02-
18/pdf/2026-03157.pdf.
Alliance for Automotive Innovation. 2025. "Reading the Meter."
https://www.autosinnovate.org/posts/papers-reports/Reading%20the%20Meter%209-5-2025.pdf.
Rogozhin, A., M. Gallaher, G. Helfand, and W. McManus. 2010. "Using indirect cost multipliers
to estimate the total cost of adding new technology in the automobile industry." International
Journal of Production Economics 124 (2): 360-368. doi: 10.1016/j .ijpe.2009.11.031.
U.S. BLS. 2025. CPI Inflation Calculator. Accessed October 23, 2025.
https://www.bls.gov/data/inflation_calculator.htm.
U.S. EIA. 2025. "Annual Energy Outlook 2025 (AEO2025)." https://www.eia.gov/outlooks/aeo/.
U.S. EPA. 2024. "Multi-Pollutant Emissions Standards for Model Years 2027 and Later Light-
Duty and Medium-Duty Vehicles - Regulatory Impact Analysis, EPA-420-R-24-004."
https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=Pl 019VPM.pdf.
U.S. EPA. 2026. "Battery Electric Vehicle Projected Market Share Analysis," Docket Report,
Docket No. EPA-HQ-OAR-2025-3297.
Umicore. 2025. Precious Metals Management - Prices. November 3. Accessed November 3,
2025. https://pmm.umicore.com/en/prices/.
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Chapter 2: Emissions, Air Quality, and Health Impacts
The EPA estimated the impact of this proposal on highway vehicle emissions of criteria
pollutants, criteria pollutant precursors, and selected air toxics by modeling national emission
inventories using a regulatory version of MOVES5 (U.S. EPA 2024b). In this chapter, the EPA
presents the estimated changes in the emissions inventory that would result from the proposed
rule and discusses the impacts on air quality and human health.
2.1 Modeled Emissions Changes from the Proposed Rule
MOVES is an emissions modeling system that estimates air pollution emissions for criteria air
pollutants and precursors, GHGs, and air toxics. MOVES covers light-, medium-, and heavy-
duty onroad vehicles such as cars, trucks and buses, and other mobile sources. MOVES accounts
for the phase-in of Federal emissions standards, vehicle and equipment activity, fuels,
temperatures, humidity, and emission control activities such as inspection and maintenance (I/M)
programs.
The version developed for this proposal, MOVES5.R3, does not contain any major
algorithmic changes relative to MOVES5, making the two versions similar in terms of their
modeling capabilities and outputs.
However, MOVES5.R3 incorporates several updates to vehicle population and activity based
on the latest information. The EPA updated vehicle miles travelled (VMT) data for 2023 and
beyond using the Federal Highway Administration's (FHWA) Highway Statistics 2023 (U.S.
DOT FHWA 2023). The EPA also updated bus populations based on the School Bus Fleet
Factbook (Hugget 2024) and the Federal Transit Administration's National Transit Database
(U.S. DOT FTA 2024) and the Agency updated future activity projections based on the Annual
Energy Outlook 2025 (AEO2025) Reference case (U.S. EIA 2025). See MOVES5 Vehicle
Population and Activity (VPAT) technical report (U.S. EPA 2024c) for other population and
activity data in MOVES5.
In addition, MOVES5.R3 includes further updates to represent the U.S. without EPA motor
vehicle and engine GHG standards and relevant Inflation Reduction Act (IRA) tax credits
(Public Law 117-169 2022), which were changed by the One Big Beautiful Bill Act (OBBB)
(Public Law 119-21 2025) described in preamble section II.B. The EPA modeled the removal of
these standards and tax credits in the no-action case by revising both the electric vehicle (EV)
projections and MOVES energy consumption rates, as described below.
For the light- and medium-duty sector, the EPA used output from a run of the Agency's
Optimization Model for reducing Emissions of Greenhouse Gases from Automobiles (OMEGA)
that did not contain the GHG portions of the LMDV Multipollutant Rule, the ACT rule for
medium-duty EV adoption, or the IRA incentives which were ended by the OBBB. The EPA
updated MOVES5.R3 to match OMEGA's projections of both EV adoption and energy
consumption for light- and medium-duty vehicles. The EV fractions from OMEGA were
incorporated in MOVES5.R3 via the sampleVehiclePopulation table in the default database. This
table describes the relative default population used in MOVES based on vehicle properties such
as fuel and engine technology.
In addition, to assess the impacts of LD EV penetration on emissions, the EPA performed
sensitivity modeling by adjusting the EV fractions projected by OMEGA for MYs 2027 and
2-1
-------
2028 by ±4 percent for each MOVES sourceTypelD, resulting in a High and a Low EV scenario.
Changes in the shares of EV population were offset by modifying the corresponding fraction of
gasoline vehicles. These adjustments were applied to passenger cars (sourceTypelD 21), light-
duty passenger trucks (sourceTypelD 31), and light-duty commercial trucks (sourceTypelD 32)
under 8,500 lbs GVWR.5 The input EV fractions used for modeling all cases are presented in
Table 1 in the Appendix. The resulting weighted light-duty EV fractions for MYs 2027 and 2028
are shown in Table 2-1 for all modeled cases.
All the updates to MOVES5.R3 described above apply to both action and no-action cases for
this proposal.
Table 2-1: Weighted Light-Duty EV Populations Modeled in MOVES for All Scenarios.
Modeling
Year
LD EV MYs 2027-2028
Scenario
population (percent)
Low
2027
7.6
2028
8.4
Central
2027
11.7
2028
12.5
High
2027
15.8
2028
16.6
2.1.1 Action Case
To model the proposed change to NMOG+NOx standards, the EPA reverted base emission
rates for passenger cars (regClassID 20) and light-duty trucks (regClassID 30) for MYs 2027 and
2028 to values corresponding to fully phased-in Tier 3 standards. These changes were applied to
emission rates representing running and start emissions of total hydrocarbons (THC)6 and NOx.
These modifications were applied in the emissionRateByAge table for all ages and operating
modes7 for the corresponding MYs referred above. In addition, the EPA also modified the
fleetAvgAdjustment table to extend the range for Tier 3 fleet averaging conditions up through
2028.
MOVES5 models PM emissions reductions from the 2024 LMDV Multipollutant Rule with
changes in the emission rates for elemental carbon (EC) PM (MOVES pollutant ID 112), and for
non-EC PM (MOVES pollutant ID 118) for MYs 2027 through 2030. To model the proposed
rule, the EPA replaced the MOVES5 PM emission rates for light-duty cars (regClassID 20) and
5 The MOVES regulatory class definition for light-duty trucks does not allow for differentiation of vehicles by
GVWR. Therefore, the adjustments made to MOVES for this proposal also affect modeled emissions for heavier
passenger and commercial trucks between 6,000 to 8,500 lbs. These adjustments were applied to both the no-action
and action cases.
6 MOVES database contains emission rates for THC and models NMOG as a chained pollutant, therefore, any
modifications done to represent changes in NMOG need to be applied to THC rates.
7 For start emission rates, these changes were applied only to rates representing "intermediate" soak periods as
described in Chapter 7.2.1.4.3 of the U.S. EPA. " Multi-Pollutant Emissions Standards for Model Years 2027 and
Later Light-Duty and Medium-Duty Vehicles. Regulatory Impact Analysis." EPA-420-R-24-004. March 2024.
Available online: https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P1019VPM.pdf.
2-2
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light-duty trucks (regClassID 30) for MYs 2027 and 2028 with their respective rates from MY
2026, representing the fully phased-in Tier 3 standards. The PM rates for all MYs except 2027
and 2028 were left unchanged.
All of the datasets used to generate MOVES5.R3, the default databases for the action case,
sensitivity scenarios, and the modeling outputs for each scenario are attached in a memorandum
to the docket (Aldridge 2026).
2.1.2 Emission changes
The EPA performed model runs for the no-action and action cases for all years between 2027
and 2055. Table 2-2 presents absolute and relative emission changes estimated for selected
pollutants and CYs. Positive values for the emission changes reflect emissions increases. Percent
changes are shown relative to the no-action case for the national onroad (light-, medium-, and
heavy-duty) inventory. The complete year-over-year air toxics results and more detailed
description of modeling are provided in the Appendix to this chapter.
Table 2-2: Annual Increases in National Onroad Emissions for Criteria Pollutants and Air
Toxics in Select CYs for the Central Scenario.
PollutantA
CY 2027
CY 2028
CY 2035
CY 2045
CY 2055
U.S.
Percent
U.S.
Percent
U.S.
Percent
U.S.
Percent
U.S.
Percent
Tons
Onroad
Tons
Onroad
Tons
Onroad
Tons
Onroad
Tons
Onroad
Nitrogen
389
<0.1
976
0.1
1031
0.2
482
0.1
106
<0.1
Oxides (NOx)
Particulate
51
0.2
145
0.5
167
1.1
102
1.6
27
0.7
Matter6
(PM2.5)
Volatile
353
<0.1
859
0.1
878
0.1
405
0.1
92
<0.1
Organic
Compounds
(VOC)
1,3-Butadiene
2
0.1
5
0.3
5
0.5
2
0.3
<1
0.1
Acetaldehyde
5
0.1
13
0.2
13
0.3
6
0.2
1
<0.1
Benzene
16
0.1
40
0.3
41
0.5
19
0.3
4
0.1
Formaldehyde
4
0.1
9
0.2
10
0.3
5
0.2
1
<0.1
r
Naphthalene
1
0.1
2
0.2
2
0.4
1
0.3
<1
0.1
Methane
90
0.1
212
0.1
228
0.1
111
<0.1
26
<0.1
Notes:
A. S02 and CO emissions do not change with this proposed rale.
B. PM2.5 changes only come from tailpipe emissions. Brake wear and tire wear emissions are not changing with this proposed rale.
C. Napthalene includes changes in both particle and gas phase components.
The estimated impact of the proposed rule on VOC is equal to or less than a 0.1 percent
increase in the total onroad vehicle emissions in the years presented. Increases in NOx are equal
to or less than 0.2 percent, while onroad PM2.5 emissions increases range between 0.2 and 1.6
percent for the years presented. The estimated impact of the proposed rule on a number of air
toxics is equal to or less than a 0.5 percent increase in the total onroad vehicle emissions in the
years presented. In general, the emissions impact of the proposal would be the largest during
2-3
-------
years when these vehicles have deteriorated but still represent a significant portion of the VMT.
As these vehicles age and are replaced due to fleet turnover, the emissions impact decreases and
the EPA estimates changes of 0.1 percent or smaller for NOx, VOC, and toxics and 0.7 percent
for PM2.5 in 2055. This proposal is not expected to impact GHG emissions, with the exception of
an increase in methane of 0.1 percent or smaller across the range of years modeled.
The sensitivity analysis, modeling scenarios with ±4 percent EV population, showed
negligible differences in emissions increases relative to the Central scenario for NOx and VOC,
as shown in Figure 2-2. For PM2.5, the sensitivity scenarios resulted in up to ±0.1 percent change
across the range of years modeled relative to the Central scenario, with the Low EV scenario
resulting in the highest emission increase. Detailed year-over-year results for the sensitivity cases
are presented in the Appendix to this chapter.
Year
Figure 2-1 Emissions Increases from No-Action Case Across the Range of Years and
Scenarios Modeled for PM2.5, NOx and VOC.
Table 2-3 presents year-over-year absolute and relative emission changes for NOx, VOC, and
tailpipe PM2.5 for the Central scenario. Positive values for the emission changes reflect emissions
increases. Percent changes are shown relative to the no-action case for the national onroad (light-
, medium-, and heavy-duty) inventory. Year-over-year results provide more insight into the
period where the largest emissions impacts would be observed, depending on the pollutant. For
NOx, the largest effect (0.2 percent increase in all onroad NOx emissions) of the proposal is
observed in the 2035-2042 period. For VOC, the largest impact (0.2 percent) is observed in
2038, while PM2.5 shows the largest effect (1.9 percent) in 2043. The absolute emissions impact
for NOx (1058 tons) and VOC (909 tons) is the largest in 2034, while for PM2.5, the largest
impact (174 tons) is in 2038.
2-4
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Table 2-3: Year-Over-Year Emissions Increases in NOx, VOC, and PM2.5 for Central
Scenario.
Year
NOx
VOC
PM2.5
U.S.
Tons
Percent
Onroad
U.S.
Tons
Percent
Onroad
U.S.
Tons
Percent
Onroad
2027
389
<0.1
353
<0.1
51
0.2
2028
976
0.1
859
0.1
145
0.5
2029
932
0.1
820
0.1
139
0.6
2030
887
0.1
780
0.1
133
0.6
2031
930
0.1
813
0.1
145
0.7
2032
1018
0.1
876
0.1
169
0.9
2033
1024
0.1
882
0.1
167
1.0
2034
1058
0.1
909
0.1
170
1.1
2035
1031
0.2
878
0.1
167
1.1
2036
1019
0.2
856
0.1
168
1.3
2037
1008
0.2
851
0.1
167
1.4
2038
1022
0.2
863
0.2
174
1.6
2039
950
0.2
802
0.1
162
1.6
2040
876
0.2
739
0.1
150
1.6
2041
796
0.2
670
0.1
135
1.6
2042
710
0.2
599
0.1
131
1.7
2043
626
0.1
530
0.1
136
1.9
2044
551
0.1
464
0.1
118
1.8
2045
482
0.1
405
0.1
102
1.6
2046
421
0.1
352
0.1
88
1.5
2047
355
0.1
301
0.1
81
1.6
2048
291
0.1
256
0.1
81
1.6
2049
253
0.1
221
<0.1
69
1.5
2050
219
0.1
191
<0.1
59
1.3
2051
189
0.1
165
<0.1
50
1.2
2052
164
<0.1
143
<0.1
43
1.0
2053
143
<0.1
124
<0.1
37
0.9
2054
123
<0.1
107
<0.1
31
0.8
2055
106
<0.1
92
<0.1
27
0.7
2.2 Air Quality Impacts of the Proposed Rule
Chapter 2.1 of this DRIA presents projections of the emission reductions that would no longer
occur under the proposed rule. The EPA did not conduct air quality modeling for this proposed
rule, and making predictions based solely on emissions changes is extremely difficult; the
atmospheric chemistry related to ambient concentrations of PM2.5, ozone, and air toxics is very
complex, and the emissions changes are spatially variable. Nevertheless, considering the air
quality modeling conducted for recent vehicle rules and the relatively small projected increase in
total on-road emissions from this proposal, overall the EPA expects relatively small changes in
ambient concentrations of air pollutants from this proposal (89 FR 27842 2024) (88 FR 4296
2023).
The EPA expects that in areas close to roadways (i.e., within 300-600 meters of the roadway),
the increased vehicle emissions could increase ambient levels of PM2.5, NO2, and other traffic-
related pollutants. Across broader geographic areas, the EPA also expects the increased vehicle
emissions to contribute to ambient concentrations of ozone, PM2.5, and air toxics which are
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secondarily formed in the atmosphere. The EPA conducted air quality modeling for the 2024
LMDV Multipollutant Rule and expects the spatial distribution of the air quality impacts from
this proposal to be similar to the spatial distribution of air quality impacts associated with the
"onroad only" results from the air quality modeling analysis for that rule (89 FR 27842 2024). It
is difficult to draw further conclusions about the air quality impacts of this proposed rule using
the analysis from the 2024 LMDV Multipollutant Rule because the no-action cases are different,
the emissions impacts are in the opposite directions, and the magnitude of the emissions impacts
from the 2024 LMDV Multipollutant Rule are much larger than the emissions impacts from this
proposed rule.
2.3 Health and Welfare Effects of Proposed Rule Related to Changes in Air Quality
As described in Chapter 2.1, the proposal would result in changes in emissions of pollutants
that contribute to ambient concentrations of PM2.5, ozone, NO2, and air toxics. There are a broad
range of health risks and welfare effects associated with exposure to these pollutants, including
premature mortality, non-fatal illnesses, and other adverse effects, including ecosystem effects.
This air pollution affects people nationwide and those who live or work near transportation
corridors. Detailed information on the health and welfare effects associated with exposure to
pollutants emitted by mobile sources and impacted by this proposed rule can be found in sections
II.B-D of the 2024 LMDV Multipollutant Rule's preamble (89 FR 27842 2024) and Chapter 6 of
its RIA (U.S. EPA 2024).
The EPA sometimes performs air quality modeling to conduct a full assessment of the PM2.5-
related and ozone-related human health benefits of the Agency's regulatory actions. As discussed
in Chapter 2.2, the EPA did not conduct air quality modeling for this proposal.
Historically, the EPA estimated the monetized benefits of avoided PM2.5- and ozone-related
impacts, which accounted for most, if not all, of the monetized benefits of many air regulations-
even when the regulation was not regulating PM2.5 or ozone. The Office of Management and
Budget (OMB), in its annual report of the Benefits and Costs of Federal Regulations, routinely
provides estimates that the monetized benefits from reducing PM2.5 and/or ozone exceed
hundreds of millions or even billions of dollars and result in most of the monetized benefits from
Federal regulations.
In previous RIAs, the EPA's approach to estimating the impacts to human health of the
changes in concentrations of ozone and PM2.5 relied substantially on information from the
Integrated Science Assessments (ISAs) for ozone and particulate matter (e.g., (U.S. EPA 2020)
(U.S. EPA 2019)). These documents synthesize the toxicological, clinical, and epidemiological
evidence to determine whether PM and ozone are causally related to an array of adverse human
health outcomes associated with either acute (i.e., hours or days-long) or chronic (i.e., years-
long) exposure; for each outcome, the ISA reports this relationship to be causal, likely to be
causal, suggestive of a causal relationship, inadequate to infer a causal relationship, or not likely
to be a causal relationship. The ISAs reflect the EPA's most up-to-date evaluation of the strength
and limitations of the available scientific evidence and clearly identify the health and welfare
endpoints for which the evidence is strongest. The EPA continues to focus on these endpoints in
considering how regulatory actions may impact public health and welfare. Historically, the EPA
has estimated the incidence of air pollution effects for those health endpoints that the ISA
classified as either causal or likely-to-be-causal and these endpoints are shown in Table 2-4. The
table below omits welfare effects such as acidification and nutrient enrichment.
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Table 2-4: Health Effects of Ambient Ozone and PM2.5
Category
Effect
Causal/Likely-to-be-
causal
More
Information
Premature mortality from
Adult premature mortality based on cohort study estimates and expert
elicitation estimates (age 65-99 or age 30-99)
/
PM ISA
exposure to PM2.5
Infant mortality (age <1)
/
PM ISA
Heart attacks (age >18)
/
PM ISA
Hospital admissions—cardiovascular (ages 65-99)
/
PM ISA
Emergency department visits— cardiovascular (age 0-99)
/
PM ISA
Hospital admissions—respiratory (ages 0-18 and 65-99)
/
PM ISA
Emergency room visits—respiratory (all ages)
/
PM ISA
Cardiac arrest (ages 0-99; excludes initial hospital and/or emergency
department visits)
/
PM ISA
Stroke (ages 65-99)
/
PM ISA
Asthma onset (ages 0-17)
/
PM ISA
Asthma symptoms/exacerbation (6-17)
/
PM ISA
Lung cancer (ages 30-99)
/
PM ISA
Nonfatal morbidity from
exposure to PM2.5
Allergic rhinitis (hay fever) symptoms (ages 3-17)
/
PM ISA
Lost work days (age 18-65)
/
PM ISA
Minor restricted-activity days (age 18-65)
/
PM ISA
Hospital admissions—Alzheimer's disease (ages 65-99)
/
PM ISA
Hospital admissions—Parkinson's disease (ages 65-99)
/
PM ISA
Other cardiovascular effects
/
PM ISA
Other respiratory effects
/
PM ISA
Other nervous system effects
/
PM ISA
Cancer
/
PM ISA
Reproductive and developmental effects
—
PM ISA
Metabolic effects
—
PM ISA
Mortality from exposure to
Premature respiratory mortality based on short-term study estimates (0-
99)
Ozone ISA
ozone
Premature respiratory mortality based on long-term study estimates (age
30-99)
Ozone ISA
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Category
Effect
Causal/Likely-to-be-
causal
More
Information
Hospital admissions—respiratory (ages 0-99)
/
Ozone ISA
Emergency department visits—respiratory (ages 0-
99)
/
Ozone ISA
Asthma onset (0-17)
/
Ozone ISA
Nonfatal morbidity from exposure to
Asthma symptoms/exacerbation (asthmatics age 2-
17)
/
Ozone ISA
ozone
Allergic rhinitis (hay fever) symptoms (ages 3-17)
/
Ozone ISA
Minor restricted-activity days (age 18-65)
/
Ozone ISA
School absence days (age 5-17)
/
Ozone ISA
Metabolic effects (e.g., diabetes)
Ozone ISA
For regulatory analyses, the EPA estimated changes in health effects in response to modeled
air quality changes for most health endpoints identified as causal or likely-to-be-causal in Table
2-4. Some endpoints were not quantified due to data availability limitations, such as for other
cardiovascular/respiratory/nervous system effects. The environmental Benefits Mapping and
Analysis Program—Community Edition (BenMAP-CE) software program was used to quantify
counts of premature deaths and illnesses attributable to photochemical modeled changes in
annual mean PM2.5 and summer season average ozone. This approach to estimating health
impacts involved two major steps: (1) developing spatial fields of air quality across the U.S. for
the baseline and regulatory scenarios using nationwide photochemical source apportionment
modeling and related analyses; and (2) using these spatial fields in BenMAP-CE to quantify
selected endpoints under each scenario and each year as compared to the baseline in that year
while accounting for the changes in population size, income growth, and baseline incidence and
prevalence rates.
Figure 2-2 summarizes the key data inputs and modeling steps for estimating the health
impacts of a regulatory impact analysis using PM2.5 inputs as an example.
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Figure 2-2: Data Inputs and Outputs for the BenMAP-CE Model Using PM2.5 as an
Example.
As the diagram above illustrates, the approach for estimating PM2.5 and ozone benefits
included health effect risk estimates from epidemiologic studies, population data, population
growth estimates, economic data for monetizing risk reductions, and assumptions regarding the
future state of the world (e.g., on-the-books regulations). Each of these inputs has unique
uncertainties associated with it. When the uncertainties from each stage of the analysis are
compounded, even small uncertainties can have large effects on the total quantified benefits.
Where possible, the EPA in the past has attempted to quantitatively assess uncertainty in each
input parameter. In some cases, quantitative analysis has not been possible due to lack of data, so
the EPA instead characterized the sensitivity of the results to alternative plausible input
parameters. And, for some inputs into the benefits analysis, such as the air quality data, the EPA
lacked the data to perform either a quantitative uncertainty analysis or sensitivity analysis.
Throughout prior RIAs, the EPA acknowledged these significant uncertainties around input
parameters and employed various techniques for characterizing the resulting uncertainty in
estimates of regulatory impacts. For example, the EPA has estimated the fraction of avoided
health effects occurring at various concentration ranges, conducted sensitivity analyses, and
employed alternate concentration-response assumptions to show how much estimates could vary
depending on which assumptions and inputs were used in primary estimates versus sensitivity
estimates.
Chapter 6 of the EPA Health Benefits TSD, Estimating PM2.5- and Ozone-Attributable Health
Benefits: 2024 Update, details the Agency's approach to characterizing uncertainty associated
with the estimation of PM2.5 and ozone benefits in both quantitative and qualitative terms (U.S.
EPA 2024a). Some of the key types of uncertainty highlighted in this chapter include:
• Statistical uncertainty around the risk estimate
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• Uncertainty around low concentration exposures and the potential for thresholds
• Uncertainty in exposure estimates
• Co-pollutant confounding
• Confounding by other individual risk factors
• Effect modification
• Application of risk estimates to other locations and populations
• Uncertainties regarding at-risk populations
• Baseline incidence rate uncertainties
• Economic valuation estimate uncertainties (e.g., income elasticity of willingness to
pay, statistical estimates of VSL, Alzheimer's and Parkinson's onset lifetime costs)
• Unquantified uncertainties (e.g., causality determination, estimating and assigning
exposures in epidemiology studies, risk attributable to long-term and short-term
exposures, shape of the concentration-response relationship)
Despite substantial investments by the EPA in approaches to characterizing uncertainties, the
RIAs have still tended to focus on point estimates for PM2.5 and ozone-related benefits.
Frequently, the EPA has utilized more than one epidemiologic study to estimate mortality
impacts because these estimates drive overall benefits for a given regulatory action due to the
large monetary value assigned to such impacts. Risk estimates using the top epidemiologic
studies sometimes differ by a factor of two or more. Presenting multiple estimates drawn directly
from the primary literature is one way to convey the prevailing uncertainty. While this leads to
an estimated range of benefits, it is not a range that reflects the true uncertainties in the
underlying parameters supporting each study, either for mortality or for other effects. Because of
the significant impacts of environmental regulations on the U.S. economy, it is essential that the
EPA has confidence in the estimated benefits of an action, and their underlying uncertainties,
prior to utilizing these estimates in a regulatory context.
A 2024 Scientific Advisory Board (SAB) reviewed the EPA's methods for estimating the
health effects of PM2.5 and clearly and repeatedly recommended that the Agency improve the
Agency's approach to characterizing and presenting the uncertainty in estimating the health
effects of PM2.5 (U.S. EPA 2024d). A Tier 1 SAB recommendation was that the EPA present a
single probabilistic mortality estimate based on pooled risk estimates with associated uncertainty
ranges rather than present multiple estimates of mortality outcomes from the epidemiologic
studies. The EPA was encouraged to explore meta-analysis methods or other forms of
information synthesis, and support research and development of modified methods as needed.
The OMB "2017 Report to Congress on the Benefits and Costs of Federal Regulations"
(OMB 2019) listed six key assumptions underpinning PM2.5 health effect estimation which
introduce substantial uncertainties in the health effect estimates:
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• That inhalation of fine particles is causally associated with premature death at
concentrations near those experienced by most Americans on a daily basis;
• That the concentration-response function for fine particles and premature mortality is
approximately linear, even for concentrations below the levels established by the
NAAQS;
• That all fine particles, regardless of their chemical composition, are equally potent in
causing premature mortality;
• That the forecasts for future emissions and associated air quality modeling accurately
predict both the baseline (state of the world absent a rule) and the air quality impacts
of the rule being analyzed;
• That BPT approaches, when used to estimate benefits, are based on regional or
national-level analysis that may not reflect local variability in population density,
meteorology, exposure, baseline health incidence rates, or other local factors; and
• That the estimated value of mortality risk reductions is an accurate reflection of what
people would be willing to pay for incremental reductions in mortality risk from air
pollution exposure, and that these values are constant across the life-cycle.
To the extent that any of these assumptions are incorrect, the benefit estimates will change,
though the magnitude and direction of change are not known with certainty. The EPA is
interested in improving understanding in each of these six areas. The EPA understands that
additional research is needed, and will begin to develop approaches that reduce these
uncertainties. The EPA will seek peer review for new methods developed from this work
consistent with the OMB's Peer Review Guidance (OMB 2005).
In particular, the EPA is interested in reevaluating the validity of the approach for estimating
the benefits of air quality improvements relative to the National Ambient Air Quality Standards
(NAAQS) for PM2.5 and ozone. These standards, which have been set at a level which the
Administrator judges to be requisite to protect public health or welfare with an adequate margin
of safety, are widely understood to represent the divide between clean air and air with an
unacceptable level of pollution. Even in instances where an assumption is found to be justified
based on scientific evidence, the EPA is interested in reevaluating its approach to characterizing
and communicating underlying uncertainty to the public.
In the past, the EPA has explored a variety of approaches to shed light on how the estimated
benefits of an action relate to the level of the NAAQS. For example, in estimating PM benefits,
the EPA has employed techniques such as cutpoint analyses and Lowest Measured Level
analyses, noting that the Agency is most confident in the magnitude of the risks projected at
PM2.5 concentrations that coincide with the bulk of the observed PM2.5 concentrations in the
epidemiological studies that are used to estimate the benefits (Regulatory Impact Analysis for the
Repeal of the Clean Power Plan, and the Emission Guidelines for Greenhouse Gas Emissions
from Existing Electric Utility Generating Units, Section 4.4.4, p. 4-26). However, such
approaches address only a few of the sources of uncertainty that influence PM-related air quality
benefits.
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The limitations of reduced-form approaches, such as the BPT approach, are even more
pronounced than photochemical modeling/BenMAP-CE approaches due to: 1) the compounding
effects of emissions reductions typically occurring across many geographic areas simultaneously,
with varying proximity to population centers; 2) differing atmospheric transformation pathways
for NOx, VOCs, and secondary PM2.5; and 3) region-specific photochemical and meteorological
conditions. Using a national BPT estimate implicitly assumes uniform marginal health benefits
for each ton of reduced emissions, an assumption not supported given heterogeneity in exposure
patterns and atmospheric chemistry. As more areas achieve or maintain attainment with the
NAAQS, the uncertainties associated with low-concentration health effects grow, and marginal
benefits become more difficult to characterize with precision.
Therefore, it may be appropriate for the EPA to separate exposures and impacts above the
level of the standard from those occurring at lower ambient concentrations. The EPA will
investigate this prior to estimating these impacts in a regulatory analysis even for informational
purposes.
2.3.1 Human Health Effects
The human health effects of increased emissions of directly emitted PM2.5, as well as NOx
(which is a precursor to ambient PM2.5), and ground-level ozone resulting from NOx and VOC
emissions, were not quantified for this rule. A qualitative description of related human health
effects is provided instead.
2.3.1.1 NOx-Related Health Effects
The Integrated Science Assessment for Oxides of Nitrogen - Health Criteria ("NOx ISA")
reviewed evidence from epidemiologic and laboratory studies on the health effects of exposure
to NOx, concluding that there is a causal relationship between respiratory health effects and
short-term exposure to NO2 (U.S. EPA 2016). Epidemiologic and experimental studies
encompassed several endpoints, including emergency department visits and hospitalizations,
respiratory symptoms, airway hyperresponsiveness, airway inflammation, and lung function. The
NOx ISA also concluded that the relationship between short-term NO2 exposure and premature
mortality was "suggestive but not sufficient to infer a causal relationship," because it is difficult
to attribute the mortality risk effects to NO2 alone. Although the NOx ISA stated that studies
consistently reported a relationship between NO2 exposure and mortality, the effect was
generally smaller than that for other pollutants such as PM. NOx emissions are also a precursor
to PM2.5 and ozone and may affect human health through these additional pathways.
2.3.1.2 Ozone-Related Health Effects
Following a comprehensive review of toxicological, clinical, and epidemiological evidence,
the Integrated Science Assessment for Ozone and Related Photochemical Oxidants ("Ozone
ISA") (U.S. EPA 2020) found both short-term (i.e., less than one month) and long-term (i.e., one
month or longer) ozone exposure to be related to an array of adverse human health effects. For
each effect, the Ozone ISA reports relationships to be causal, likely to be causal, suggestive of a
causal relationship, inadequate to infer a causal relationship, or not likely to be a causal
relationship. This assessment is based on the body of scientific evidence which can include
observational human studies, experimental human exposure studies, animal model studies, and
mechanistic studies.
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The Ozone ISA found short-term exposure to ozone to be causally related to respiratory
effects, including respiratory mortality, and likely to be causally related to metabolic effects. For
short-term exposure, evidence was suggestive of a causal relationship for cardiovascular and
nervous system effects as well as total mortality. The Ozone ISA reported that long-term
exposure to ozone is likely-to-be-causally related to respiratory effects, including respiratory
mortality. Evidence on metabolic, cardiovascular, reproductive, and nervous system effects as
well as total mortality was suggestive of a causal relationship with long-term ozone exposure.
When adequate data and resources are available, the EPA has generally quantified health
effects which the Ozone ISA classified as causally related or likely-to-be-causally related to
short- or long-term ozone exposure. Health effects classified as suggestive-of-causality or
weaker have not historically been quantified. Historically quantified health effects include
premature respiratory mortality, hospital admissions and emergency department visits, asthma
onset and related symptoms (chest tightness, cough, shortness of breath, and wheeze), allergic
rhinitis symptoms, and restricted activity days and school absences. The EPA did not quantify or
monetize the disbenefits associated with changes in the incidence of the listed health effects of
this rule.
2.3.1.3 PM2.5-Related Health Effects
PM2.5 describes an array of pollutants from human and natural sources with diameters that are
generally 2.5 micrometers and smaller. This includes directly emitted PM2.5 as well as PM2.5
formed through atmospheric chemical reactions of precursor pollutants, including NOx.
Following a comprehensive review of toxicological, clinical, and epidemiological evidence,
the Integrated Science Assessment for Particulate Matter ("PM ISA") (U.S. EPA 2019) and the
Supplement to the Integrated Science Assessment for Particulate Matter ("PM ISA Supplement")
(U.S. EPA 2022) found PM2.5 to be related to an array of adverse human health effects. For each
effect, the PM ISA and PM ISA Supplement report relationships to be causal, likely to be causal,
suggestive of a causal relationship, inadequate to infer a causal relationship, or not likely to be a
causal relationship. This assessment is based on the body of scientific evidence which can
include observational human studies, experimental human exposure studies, animal model
studies, and mechanistic studies.
The PM ISA and PM ISA Supplement found acute and chronic exposures to PM2.5 to be
causally related to cardiovascular effects and total mortality (i.e., premature death), and
respiratory effects as likely-to-be-causally related. Chronic exposures to PM2.5 were also
determined to be likely-to-be-causally related to nervous system effects and cancer, with the
latter determination based primarily on evidence from studies of lung cancer incidence as well as
decades of research on the mutagenicity and carcinogenicity of PM. Evidence was suggestive of
a causal relationship for reproductive and developmental effects, pregnancy and birth outcomes,
and metabolic effects.
When adequate data and resources are available, the EPA has generally quantified health
effects which the PM ISA and PM ISA Supplement classified as causally related or likely-to-be-
causally related to PM2.5 exposure. Health effects classified as suggestive-of-causality or weaker
have not historically been quantified. Historically quantified health effects include premature
mortality, heart attacks, cardiovascular hospital admissions, cardiovascular emergency
department visits, respiratory hospital admissions, respiratory emergency room visits, cardiac
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arrest, stroke, asthma onset, asthma symptoms/exacerbation, lung cancer, allergic rhinitis (hay
fever) symptoms, lost workdays, and minor restricted-activity days. The EPA did not quantify or
monetize the disbenefits associated with changes in the incidence of the listed health effects for
this rule.
2.3.2 Welfare Effects
Due to operational constraints and data limitations, most benefits analyses focus on human
health effects expected to occur because of changes in primary and secondary pollutant
concentrations resulting from the rulemaking. However, the benefits of reductions in emissions
of air pollutants include additional effects that include, but are not limited to: effects on soils,
water, crops, vegetation, manmade materials, animals, wildlife, weather, visibility, and climate,
damage to and deterioration of property, and hazards to transportation, as well as effects on
economic values and on personal comfort and well-being, whether caused by transformation,
conversion, or combination with other pollutants (42 U.S.C. §7602(h)). In this chapter, the EPA
provides qualitative discussions of select welfare effects.
2.3.2.1 Ozone Welfare Effects
2.3.2.1.1 Vegetation and Ecosystem Effects
Exposure to ozone has been found to be associated with a wide array of vegetation and
ecosystem effects in the published literature (U.S. EPA 2020). Sensitivity to ozone is highly
variable across species, with over 66 vegetation species identified as "ozone-sensitive," many of
which occur in State and national parks and forests. These effects include those that cause
damage to, or impairment of, the intended use of the plant or ecosystem. Such effects are
considered adverse to public welfare and can include reduced growth and/or biomass production
in sensitive trees, reduced yield and quality of crops, visible foliar injury, changes to species
composition, and changes in ecosystems and associated ecosystem services (U.S. EPA 2020).
2.3.2.1.2 Animal Welfare Effects
While effects can be context- and species-specific, a large body of scientific evidence links
ozone exposure to health effects in animals. When exploring environmental pathways through
which environmental effects of ozone may impact animals, the Ozone ISA found a likely-to-be-
causal relationship between ambient ozone concentrations and alterations of herbivore growth
and reproduction (U.S. EPA 2020). In addition, many animal toxicological studies served as
evidence for determining the causality of relationships between human exposure to ozone and
human health effects, including respiratory and metabolic effects. The Ozone ISA states "A large
body of experimental animal toxicological studies demonstrates (short- and long-term) ozone-
induced changes in measures of lung function, inflammation, increased airway responsiveness,
and impaired lung host defense" (U.S. EPA 2020). Additionally, animal studies report
relationships between short-term ozone exposure and metabolic effects in various stocks and
strains of animals across multiple laboratories (U.S. EPA 2020).
2.3.2.2 PM2.5 Welfare Effects
2.3.2.2.1 Visibility Effects
Reducing secondary formation of PM2.5 would improve levels of visibility in the U.S. because
suspended particles and gases degrade visibility by scattering and absorbing light (U.S. EPA
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2019). Fine particles with significant light-extinction efficiencies include sulfates, nitrates,
organic carbon, elemental carbon, and soil. Visibility has direct significance to people's
enjoyment of daily activities and their overall sense of wellbeing. Good visibility increases the
quality of life where individuals live and work, and where they engage in recreational activities.
Particulate sulfate is the dominant source of regional haze in the eastern U.S. and particulate
nitrate is an important contributor to light extinction in California (U.S. EPA 2019). Previous
analyses such as (U.S. EPA 2012) show that visibility benefits can be a significant welfare
benefit category.
2.3.2.2.2 Animal Welfare Effects
While effects can be context- and species-specific, a large body of scientific evidence links
PM2.5 exposure to health effects in animals. The PM ISA (U.S. EPA 2019) and PM ISA
Supplement (U.S. EPA 2022) evaluated exposures to PM2.5 and an array of health markers
described in animal toxicological studies. Animal toxicological studies have found evidence that
PM2.5 induces changes in measurements including, but not limited to, breathing patterns, airway
irritation, impaired heart function, changes in blood pressure, oxidative stress, reproductive
outcomes, and other outcomes. However, neither the PM ISA nor the PM ISA Supplement
provide a causality determination of the causality of PM2.5 affecting animal health.
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References
88 FR 4296. 2023. (January 24). https://www.federalregister.gov/documents/2023/01/24/2022-
27957/control-of-air-pollution-from-new-motor-vehicles-heavy-duty-engine-and-vehicle-
standards.
89 FR 27842. 2024. (April 18). https://www.federalregister.gov/documents/2024/04/18/2024-
06214/multi-pollutant-emissions-standards-for-model-years-2027-and-later-light-duty-and-
medium-duty.
91 FR7686. 2026. (February 18). https://www.govinfo.gov/content/pkg/FR-2026-02-
18/pdf/2026-03157.pdf.
Aldridge, Michael. 2026. "MOVES Modeling for NPRM, Memorandum to Docket EPA-HQ-
OAR-2025-3297."
Hugget, A., ed. 2024. "2025 Fact Book - Pupil Transportation by the Numbers." School Bus
Fleet, December.
https://schoolbusfleet.mydigitalpublication.com/publication/?i=837102&p=0&view=issueViewe
r.
OMB. 2019. "2017 Report to Congress on Benefits and Costs of Federal Regulations and
Agency Compliance with the Unfunded Mandates Reform Act." Washington, DC. Available at
https://trumpwhitehouse.archives.gov/wp-content/uploads/2019/12/2019-CATS-5885-
REVDOC-2017Cost_BenefitReportl 1 18 2019.docx.pdf.
—. 2005. "Memorandum M-05-03, Memorandum for the Heads of Executive Departments and
Agencies: Issuance of OMB's Final Information Quality Bulletin for Peer Review." Washington,
DC. Available at: https://www.federalregister.gov/documents/2005/01/14/05-769/final-
information-quality-bulletin-for-peer-review.
Public Law 117-169. 2022. (August 16). https://www.congress.gov/117/plaws/publl69/PLAW-
117publl69.pdf.
Public Law 119-15. 2025. (June 12). https://www.congress.gov/119/plaws/publl5/PLAW-
119publl5.pdf.
Public Law 119-21. 2025. (July 4). https://www.congress.gov/119/plaws/publ21/PLAW-
119publ21.pdf.
U.S. DOT FHWA. 2023. "Highway Statistics Series: Highway Statistics 2023. Table VM-1."
https://www.fhwa.dot.gov/policyinformation/statistics/2023/vml.cfm.
U.S. DOT FTA. 2024. National Transit Database - 2023 Annual Database Revenue Vehicle
Inventory, https://www.transit.dot.gov/ntd/data-product/2023-annual-database-revenue-vehicle-
inventory.
U.S. EIA. 2025. "Annual Energy Outlook 2025." https://www.eia.gov/outlooks/aeo/.
U.S. EPA. 2024a. "Estimating PM2.5- and Ozone-Attributable Health Benefits: 2024 Update."
Research Triangle Park, NC: U.S. Environmental Protection Agency, Office of Air and
2-16
-------
Radiation, https://www.epa.gov/system/files/documents/2024-06/estimating-pm2.5-and-ozone-
attributable-health-benefits-tsd-2024.pdf.
—. 2020. "Integrated Science Assessment (ISA) for Ozone and Related Photochemical Oxidants.
(EPA/600/R-20/012)." Washington, DC. Available at:
https://assessments.epa.gov/risk/document/&deid=348522.
—. 2019. "Integrated Science Assessment (ISA) for Particulate Matter. (EPA/600/R-19/188."
Washington, DC. Available at: https://assessments.epa.gov/risk/document/&deid=347534.
—. 2016. "Integrated Science Assessment for Oxides of Nitrogen - Health Criteria." Research
Triangle Park, NC: Office of Research and Development, National Center for Environmental
Assessment. Available at: https://cfpub.epa.gov/ncea/isa/recordisplay.cfm?deid=310879.
U.S. EPA. 2024b. MOtor Vehicle Emission Simulator (MOVES), Version 5.0.0.
https://www.epa.gov/moves.
U.S. EPA. 2024. "Multi-Pollutant Emissions Standards for Model Years 2027 and Later Light-
Duty and Medium-Duty Vehicles - Regulatory Impact Analysis, EPA-420-R-24-004."
https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=Pl 019VPM.pdf.
U.S. EPA. 2024c. "Population and activity of Onroad Vehicles in MOVES5, EPA-420-R-24-
019." Assessment and Standards Division, Office of Transportation and Air Quality .
https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=Pl 01CUN7.pdf.
—. 2012. "Regulatory Impact Analysis for the Final Revisions to the National Ambient Air
Quality Standards for Particulate Matter (EPA-452/R-12-005)." Research Triangle Park, NC:
Office of Air Quality Planning and Standards, Health and Environmental Impact Division.
Available at: https://www3.epa.gov/ttnecasl/regdata/RIAs/finalria.pdf.
—. 2024d. "Review of BenMAP and Benefits Methods (EPA/SAB/24/003)." Washington, DC:
U.S. Environmental Protection Agency. Available at:
https://sab.epa.gov/ords/sab/r/sab_apex/sab/advisoryactivitydetail?pl8_id=2617&clear=18&sess
ion= 15054897040198#report.
—. 2022. "Supplement to the 2019 Integrated Science Assessment for Particulate Matter (Final
Report) (EPA/600/R-22/028)." Research Triangle Park, NC: Office of Research and
Development, Center for Public Health and Environmental Assessment. Available at:
https://cfpub. epa.gov/ncea/isa/recordisplay. cfm?deid=354490.
2-17
-------
Appendix to Chapter 2
This Appendix contains additional details about the emissions inventory modeling described
in Chapter 2 along with more detailed year-over-year emission changes from the modeled
scenarios.
MOVES runs and post-processing details
For both the action and no-action cases, national annual emissions inventories were calculated
using MOVES for calendar years between 2027 and 2055. All MOVES runs were performed at
the default scale, where no custom inputs were used except for the default databases. The default
databases for each case were modified versions of the MOVES5 default database with the
changes described in Chapter 2.1. Each MOVES run included all combinations of vehicle types,
fuel types, and road types. Exhaust emissions, along with refueling, brake wear, and tire wear
emissions were calculated for each State and the District of Columbia using State-level pre-
aggregation and monthly temporal pre-aggregation. Evaporative emissions were calculated using
national scale geographic pre-aggregation and full hourly temporal detail.
The output of these MOVES runs is a large collection of Structured Query Language (SQL)
relational databases. The EPA post-processed these databases to create a single, more
compressed version for each modeling case. The post-processed databases were then used for the
analyses estimating the emission impacts of the proposed rule. The post-processing was done
using R, an open-source programming language used primarily for data science and statistical
analysis. For each modeling case, the outputs of the exhaust and evaporative emissions
calculations were combined and summed over the yearlD, pollutantID, processID,
sourceTypelD, regClassID, fuelTypelD, and modelYearlD fields. The result was a single SQL
database containing annual national emissions inventory for each modeled case. Table 2A- 1
presents the light-duty EV fractions used as input in MOVES while Table 2A- 2 through Table
2A- 8 show year-over-year emissions changes for selected pollutants for the Central case, as well
as sensitivity cases, relative to the no-action case.
2A-1
-------
Table 2A-1: Input LD EV Fractions Incorporated in MOVES for All Modeling Cases.
Modeling
Model Year
MOVES
Vehicle Type
EV Population
Scenario
Regulatory
Class
(Percent)
Low EV
2027
20
Cars
13.9
30
Passenger Trucks
4.5
Commercial Trucks
3.1
2028
20
Cars
19.8
30
Passenger Trucks
10.1
Commercial Trucks
8.5
Central
2027
20
Cars
17.9
30
Passenger Trucks
8.5
Commercial Trucks
7.1
2028
20
Cars
19.8
30
Passenger Trucks
10.1
Commercial Trucks
8.5
HighEV
2027
20
Cars
21.9
30
Passenger Trucks
12.5
Commercial Trucks
11.1
2028
20
Cars
23.8
30
Passenger Trucks
14.1
Commercial Trucks
12.5
2A-2
-------
Table 2A-2: Year-Over-Year Emissions Increases in NOx, VOC, and PM2.5 for Sensitivity
Cases.
Low EV
High EV
Year
NOx
VOC
PM2.5
NOx
VOC
PM2.5
U.S.
Tons
Percent
Onroad
U.S.
Tons
Percent
Onroad
U.S.
Tons
Percent
Onroad
U.S.
Tons
Percent
Onroad
U.S.
Tons
Percent
Onroad
U.S.
Tons
Percent
Onroad
2027
389
<0.1
353
<0.1
53
0.2
389
<0.1
352
<0.1
48
0.2
2028
976
0.1
859
0.1
152
0.6
976
0.1
859
0.1
138
0.5
2029
932
0.1
820
0.1
146
0.6
932
0.1
820
0.1
132
0.5
2030
887
0.1
780
0.1
140
0.6
887
0.1
780
0.1
127
0.6
2031
930
0.1
813
0.1
151
0.7
930
0.1
812
0.1
138
0.7
2032
1018
0.1
876
0.1
177
0.9
1018
0.1
876
0.1
161
0.9
2033
1024
0.1
882
0.1
175
1.0
1024
0.1
882
0.1
160
0.9
2034
1058
0.1
909
0.1
178
1.1
1058
0.1
909
0.1
162
1.0
2035
1031
0.2
879
0.1
174
1.2
1031
0.2
878
0.1
159
1.1
2036
1019
0.2
857
0.1
176
1.3
1019
0.2
856
0.1
160
1.2
2037
1008
0.2
851
0.1
175
1.4
1008
0.2
851
0.1
159
1.3
2038
1022
0.2
863
0.2
183
1.7
1022
0.2
863
0.2
166
1.5
2039
950
0.2
802
0.1
170
1.7
950
0.2
802
0.1
154
1.5
2040
876
0.2
739
0.1
157
1.7
876
0.2
739
0.1
142
1.5
2041
796
0.2
670
0.1
142
1.7
796
0.2
670
0.1
129
1.5
2042
710
0.2
599
0.1
137
1.7
711
0.2
599
0.1
125
1.6
2043
626
0.1
530
0.1
142
1.9
626
0.1
530
0.1
129
1.8
2044
550
0.1
464
0.1
123
1.8
551
0.1
464
0.1
112
1.7
2045
482
0.1
405
0.1
107
1.7
482
0.1
405
0.1
97
1.6
2046
421
0.1
351
0.1
92
1.6
421
0.1
352
0.1
84
1.4
2047
355
0.1
301
0.1
85
1.6
355
0.1
301
0.1
77
1.5
2048
291
0.1
255
0.1
84
1.7
291
0.1
256
0.1
77
1.6
2049
253
0.1
221
<0.1
72
1.5
253
0.1
221
<0.1
66
1.4
2050
219
0.1
191
<0.1
62
1.4
219
0.1
191
<0.1
56
1.3
2051
189
<0.1
165
<0.1
53
1.2
190
0.1
165
<0.1
48
1.1
2052
164
<0.1
143
<0.1
45
1.1
164
<0.1
143
<0.1
41
1.0
2053
143
<0.1
124
<0.1
38
1.0
143
<0.1
124
<0.1
35
0.9
2054
123
<0.1
107
<0.1
33
0.9
123
<0.1
107
<0.1
30
0.8
2055
106
<0.1
92
<0.1
28
0.8
107
<0.1
92
<0.1
26
0.7
2A-3
-------
Table 2A-3: Year-Over-Year Emissions Increases in VOC, NOx and PM2.sfor Gasoline
Cars, Gasoline Trucks, and Diesel Vehicles for the Central Case.
Year
NOx (U.S. Tons)
PM2.5 (U.S. Tons)
VOC (U.S. Tons)
Gasoline
Cars
Gasoline
Trucks
Diesel
Vehicle
Gasoline
Cars
Gasoline
Trucks
Diesel
Vehicle
Gasoline
Cars
Gasoline
Trucks
Diesel
Vehicle
2027
142
244
3
22
29
<1
133
218
2
2028
344
625
6
61
84
1
314
541
4
2029
328
598
6
58
80
1
299
517
4
2030
312
569
6
56
77
1
284
492
4
2031
311
612
6
57
87
1
286
522
4
2032
317
693
7
62
107
1
295
576
5
2033
309
707
8
62
105
1
291
586
5
2034
304
746
8
64
105
1
290
613
5
2035
294
728
8
63
102
1
282
591
5
2036
288
723
8
65
102
1
275
576
5
2037
284
716
8
66
100
1
280
566
5
2038
287
728
8
72
102
1
291
566
5
2039
267
675
7
67
95
1
272
525
5
2040
245
623
7
62
87
1
250
485
4
2041
217
573
6
55
80
1
221
446
4
2042
185
520
6
52
79
1
189
406
4
2043
155
466
5
54
81
1
160
366
3
2044
127
419
4
44
73
1
132
329
3
2045
104
374
4
36
65
<1
108
294
3
2046
83
334
4
29
58
<1
87
262
2
2047
66
286
3
26
55
<1
69
230
2
2048
52
236
2
25
55
<1
56
198
2
2049
41
209
2
20
49
<1
44
176
2
2050
32
184
2
15
43
<1
35
155
1
2051
25
162
2
12
38
<1
27
137
1
2052
20
143
2
9
33
<1
21
121
1
2053
15
126
1
7
29
<1
17
107
1
2054
12
110
1
6
26
<1
13
93
1
2055
9
96
1
4
22
<1
10
82
1
2A-4
-------
Table 2A-4: Year-Over-Year Emissions Increases in VOC, NOx and PM2.sfor Gasoline
Cars, Gasoline Trucks, and Diesel Vehicles for the Low EV Case.
Year
NOx (U.S. Tons)
PM2.5 (U.S. Tons)
VOC (U.S. Tons)
Gasoline
Gasoline
Diesel
Gasoline
Gasoline
Diesel
Gasoline
Gasoline
Diesel
Cars
Trucks
Vehicle
Cars
Trucks
Vehicle
Cars
Trucks
Vehicle
2027
143
244
3
23
30
<1
133
218
2
2028
345
625
6
64
87
1
315
540
4
2029
329
597
6
61
84
1
300
516
4
2030
313
569
6
59
81
1
285
492
4
2031
312
612
6
60
91
1
287
522
4
2032
318
693
7
65
112
1
295
576
5
2033
310
707
7
65
110
1
291
586
5
2034
305
745
8
67
110
1
291
612
5
2035
295
728
7
67
107
1
282
591
5
2036
288
723
7
68
106
1
276
575
5
2037
285
715
7
70
105
1
281
566
5
2038
287
727
7
75
107
1
292
566
5
2039
268
675
7
70
99
1
272
525
4
2040
246
623
6
65
91
1
250
485
4
2041
217
572
6
57
84
1
221
445
4
2042
185
520
5
55
82
1
190
406
3
2043
155
466
5
56
85
1
161
366
3
2044
128
418
4
47
76
1
133
329
3
2045
104
374
4
38
68
<1
108
294
2
2046
84
334
3
31
61
<1
87
262
2
2047
67
286
3
27
58
<1
70
229
2
2048
53
236
2
26
58
<1
56
198
2
2049
41
209
2
21
51
<1
44
176
1
2050
33
184
2
16
45
<1
35
155
1
2051
25
162
2
13
40
<1
27
137
1
2052
20
143
1
10
35
<1
21
121
1
2053
16
126
1
8
31
<1
17
107
1
2054
12
110
1
6
27
<1
13
93
1
2055
9
96
1
5
23
<1
10
82
1
2A-5
-------
Table 2A-5: Year-Over-Year Emissions Increases in VOC, NOx and PM2.sfor Gasoline
Cars, Gasoline Trucks, and Diesel Vehicles for the High EV Case.
Year
NOx (U.S. Tons)
PM2.5 (U.S. Tons)
VOC (U.S. Tons)
Gasoline
Gasoline
Diesel
Gasoline
Gasoline
Diesel
Gasoline
Gasoline
Diesel
Cars
Trucks
Vehicle
Cars
Trucks
Vehicle
Cars
Trucks
Vehicle
2027
143
244
3
23
30
<1
133
218
2
2028
345
625
6
64
87
1
315
540
4
2029
329
597
6
61
84
1
300
516
4
2030
313
569
6
59
81
1
285
492
4
2031
312
612
6
60
91
1
287
522
4
2032
318
693
7
65
112
1
295
576
5
2033
310
707
7
65
110
1
291
586
5
2034
305
745
8
67
110
1
291
612
5
2035
295
728
7
67
107
1
282
591
5
2036
288
723
7
68
106
1
276
575
5
2037
285
715
7
70
105
1
281
566
5
2038
287
727
7
75
107
1
292
566
5
2039
268
675
7
70
99
1
272
525
4
2040
246
623
6
65
91
1
250
485
4
2041
217
572
6
57
84
1
221
445
4
2042
185
520
5
55
82
1
190
406
3
2043
155
466
5
56
85
1
161
366
3
2044
128
418
4
47
76
1
133
329
3
2045
104
374
4
38
68
<1
108
294
2
2046
84
334
3
31
61
<1
87
262
2
2047
67
286
3
27
58
<1
70
229
2
2048
53
236
2
26
58
<1
56
198
2
2049
41
209
2
21
51
<1
44
176
1
2050
33
184
2
16
45
<1
35
155
1
2051
25
162
2
13
40
<1
27
137
1
2052
20
143
1
10
35
<1
21
121
1
2053
16
126
1
8
31
<1
17
107
1
2054
12
110
1
6
27
<1
13
93
1
2055
9
96
1
5
23
<1
10
82
1
2A-6
-------
Table 2A-6: Year-Over-Year Emissions Increases for Select Air Toxics for Central Case.
Year
1,3-Butadiene
Acet aldehyde
Benzene
Formaldehyde
Naphthalene
U.S.
Percent
U.S.
Percent
U.S.
Percent
U.S.
Percent
U.S.
Percent
tons
Onroad
tons
Onroad
tons
Onroad
tons
Onroad
tons
Onroad
2027
2
0.1
5
0.1
16
0.1
4
0.1
1
0.1
2028
5
0.3
13
0.2
40
0.3
9
0.2
2
0.2
2029
5
0.3
13
0.2
38
0.3
9
0.2
2
0.3
2030
4
0.3
12
0.2
36
0.3
9
0.2
2
0.3
2031
5
0.4
13
0.3
38
0.4
9
0.2
2
0.3
2032
5
0.4
13
0.3
41
0.4
10
0.2
2
0.4
2033
5
0.5
14
0.3
41
0.4
10
0.2
2
0.4
2034
5
0.5
14
0.3
42
0.5
10
0.3
2
0.4
2035
5
0.5
13
0.3
41
0.5
10
0.3
2
0.4
2036
5
0.5
13
0.3
40
0.5
10
0.3
2
0.5
2037
4
0.5
13
0.3
40
0.5
10
0.3
2
0.5
2038
4
0.6
13
0.4
40
0.5
10
0.3
2
0.6
2039
4
0.5
12
0.3
37
0.5
9
0.3
2
0.5
2040
4
0.5
11
0.3
34
0.5
8
0.3
2
0.5
2041
3
0.5
10
0.3
31
0.5
8
0.3
1
0.5
2042
3
0.4
9
0.3
28
0.4
7
0.2
1
0.5
2043
3
0.4
8
0.2
25
0.4
6
0.2
1
0.4
2044
2
0.4
7
0.2
22
0.3
5
0.2
1
0.4
2045
2
0.3
6
0.2
19
0.3
5
0.2
1
0.3
2046
2
0.3
5
0.1
16
0.3
4
0.1
1
0.3
2047
2
0.2
4
0.1
14
0.2
3
0.1
1
0.3
2048
1
0.2
4
0.1
12
0.2
3
0.1
1
0.2
2049
1
0.2
3
0.1
10
0.2
3
0.1
<1
0.2
2050
1
0.2
3
0.1
9
0.2
2
0.1
<1
0.2
2051
1
0.1
2
0.1
8
0.1
2
0.1
<1
0.2
2052
1
0.1
2
0.1
7
0.1
2
<0.1
<1
0.1
2053
1
0.1
2
<0.1
6
0.1
1
<0.1
<1
0.1
2054
1
0.1
2
<0.1
5
0.1
1
<0.1
<1
0.1
2055
<1
0.1
5
0.1
4
0.1
4
0.1
1
0.1
2A-7
-------
Table 2A-7: Year-Over-Year Emissions Increases for Select Air Toxics for Low EV Case.
Year
1,3-Butadiene
Acet aldehyde
Benzene
Formaldehyde
Naphthalene
U.S.
Percent
U.S.
Percent
U.S.
Percent
U.S.
Percent
U.S.
Percent
tons
Onroad
tons
Onroad
tons
Onroad
tons
Onroad
tons
Onroad
2027
2
0.1
5
0.1
16
0.1
4
0.1
1
0.1
2028
5
0.3
13
0.2
40
0.3
9
0.2
2
0.2
2029
5
0.3
13
0.2
38
0.3
9
0.2
2
0.3
2030
4
0.3
12
0.2
36
0.3
9
0.2
2
0.3
2031
5
0.4
13
0.3
38
0.4
9
0.2
2
0.3
2032
5
0.4
13
0.3
41
0.4
10
0.2
2
0.4
2033
5
0.5
14
0.3
41
0.4
10
0.2
2
0.4
2034
5
0.5
14
0.3
42
0.5
10
0.3
2
0.4
2035
5
0.5
13
0.3
41
0.5
10
0.3
2
0.4
2036
5
0.5
13
0.3
40
0.5
10
0.3
2
0.5
2037
4
0.5
13
0.3
40
0.5
10
0.3
2
0.5
2038
4
0.6
13
0.4
40
0.5
10
0.3
2
0.6
2039
4
0.5
12
0.3
37
0.5
9
0.3
2
0.5
2040
4
0.5
11
0.3
34
0.5
8
0.3
2
0.5
2041
3
0.5
10
0.3
31
0.5
8
0.3
1
0.5
2042
3
0.4
9
0.3
28
0.4
7
0.2
1
0.5
2043
3
0.4
8
0.2
25
0.4
6
0.2
1
0.4
2044
2
0.4
7
0.2
22
0.3
5
0.2
1
0.4
2045
2
0.3
6
0.2
19
0.3
5
0.2
1
0.3
2046
2
0.3
5
0.1
16
0.3
4
0.1
1
0.3
2047
2
0.2
4
0.1
14
0.2
3
0.1
1
0.3
2048
1
0.2
4
0.1
12
0.2
3
0.1
1
0.2
2049
1
0.2
3
0.1
10
0.2
3
0.1
<1
0.2
2050
1
0.2
3
0.1
9
0.2
2
0.1
<1
0.2
2051
1
0.1
2
0.1
8
0.1
2
0.1
<1
0.2
2052
1
0.1
2
0.1
7
0.1
2
<0.1
<1
0.1
2053
1
0.1
2
<0.1
6
0.1
1
<0.1
<1
0.1
2054
1
0.1
2
<0.1
5
0.1
1
<0.1
<1
0.1
2055
<1
0.1
5
0.1
4
0.1
1
<0.1
<1
0.1
2A-8
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Table 2A-8: Year-Over-Year Emissions Increases for Select Air Toxics for High EV Case.
Year
1,3-Butadiene
Acet aldehyde
Benzene
Formaldehyde
Naphthalene
U.S.
Percent
U.S.
Percent
U.S.
Percent
U.S.
Percent
U.S.
Percent
tons
Onroad
tons
Onroad
tons
Onroad
tons
Onroad
tons
Onroad
2027
2
0.1
5
0.1
16
0.1
4
0.1
1
0.1
2028
5
0.3
13
0.2
40
0.3
9
0.2
2
0.2
2029
5
0.3
13
0.2
38
0.3
9
0.2
2
0.3
2030
4
0.3
12
0.2
36
0.3
9
0.2
2
0.3
2031
5
0.4
13
0.3
38
0.4
9
0.2
2
0.3
2032
5
0.4
13
0.3
41
0.4
10
0.2
2
0.4
2033
5
0.5
14
0.3
41
0.4
10
0.2
2
0.4
2034
5
0.5
14
0.3
42
0.5
10
0.3
2
0.4
2035
5
0.5
13
0.3
41
0.5
10
0.3
2
0.4
2036
5
0.5
13
0.3
40
0.5
10
0.3
2
0.5
2037
4
0.5
13
0.3
40
0.5
10
0.3
2
0.5
2038
4
0.6
13
0.4
40
0.5
10
0.3
2
0.6
2039
4
0.5
12
0.3
37
0.5
9
0.3
2
0.5
2040
4
0.5
11
0.3
34
0.5
9
0.3
2
0.5
2041
3
0.5
10
0.3
31
0.5
8
0.3
1
0.5
2042
3
0.4
9
0.3
28
0.4
7
0.2
1
0.5
2043
3
0.4
8
0.2
25
0.4
6
0.2
1
0.4
2044
2
0.4
7
0.2
22
0.3
5
0.2
1
0.4
2045
2
0.3
6
0.2
19
0.3
5
0.2
1
0.3
2046
2
0.3
5
0.2
16
0.3
4
0.1
1
0.3
2047
2
0.2
4
0.1
14
0.2
4
0.1
1
0.3
2048
1
0.2
4
0.1
12
0.2
3
0.1
1
0.2
2049
1
0.2
3
0.1
10
0.2
3
0.1
<1
0.2
2050
1
0.2
3
0.1
9
0.2
2
0.1
<1
0.2
2051
1
0.1
2
0.1
8
0.1
2
0.1
<1
0.2
2052
1
0.1
2
0.1
7
0.1
2
<0.1
<1
0.1
2053
1
0.1
2
<0.1
6
0.1
1
<0.1
<1
0.1
2054
1
0.1
2
<0.1
5
0.1
1
<0.1
<1
0.1
2055
<1
0.1
1
<0.1
4
0.1
1
<0.1
<1
0.1
2A-9
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Chapter 3: Comparison of Benefits and Costs
This chapter summarizes the estimated cost savings and the non-monetized impacts of the
proposed action. Program costs are presented in Chapter 1 of this DRIA. Cost savings are those
associated with PM reduction technology that would no longer be required by this proposal. As
noted in Chapter 2.3, the EPA did not quantify or monetize the health disbenefits associated with
emissions increases. The net benefits associated with the proposed action are the cost savings,
which are presented in year 2024 dollars.
3.1 Methods
The EPA presents cost savings using three different methods:
1) CY cost savings in years 2027 and 2028, when implementation of the proposed action will
apply to MY 2027 and MY 2028 vehicles, respectively. Cost savings in these years are not
discounted.
2) The present value (PV) of the stream of cost savings, which represents projected savings
incurred in CYs 2027 and 2028, discounted back to 2027 and assuming end of year
discounting. PVs are estimated using both a 3-percent and 7-percent discount rate.
3) The equivalent annualized value (AV) of cost savings, representing a flow of constant AVs
that, had they occurred in each year from 2027 to 2055, would yield an equivalent PV to the
PV described above (using either a 3-percent or 7-percent discount rate). Each AV represents
a typical cost savings for each year of the analysis and is presented in year 2024 dollars.
3.2 Results
Table 3-1 presents the cost savings and non-monetized disbenefits of the proposed rule.
Monetized cost savings are presented in undiscounted annual terms for CYs 2027 and 2028, in
PV and AV terms.
3-1
-------
Table 3-1: Costs and Benefits of the Proposal (millions, 2024$).a'd
CY 2027
CY 2028
PV, 3%
PV, 7%
AV, 3%°
AV, 7%°
Cost Savings
forPM
Control
$220
$510
$690
$650
$36
$53
Cost Savings
for
NMOG+NOx
Control
$470
$660
$1,070
$1,010
$56
$82
Sum of Cost
Savings
$690
$1,170
$1,770
$1,660
$92
$135
Non-Monetized Impacts'3
Impacts to human health and the enviromnent from increased exposure to ambient PM2.5. ozone, NO2, air toxics,
and methane (see Chapter 2.3)
a Totals may not sum due to rounding.
b Several categories of costs and benefits remain unmonetized and are not reflected in the table,
c Annualized values are based on a time horizon beginning in 2027 and ending in 2055.
d EPA notes there are uncertainties associated with these cost savings projections. See section III.A of the preamble, and the Executive Summary
and Chapter 1 of this DRIA for a discussion of uncertainties.
3-2
-------
Chapter 4: Small Business Flexibilities
The Regulatory Flexibility Act, as amended by the Small Business Regulatory Enforcement
Fairness Act of 1996 (SBREFA), generally requires an agency to prepare a regulatory flexibility
analysis of any rule subject to notice-and-comment rulemaking requirements under the
Administrative Procedure Act or any other statute. As a part of this analysis, an agency is
directed to convene a Small Business Advocacy Review Panel (SBAR Panel or ' Panel'), unless
the agency certifies that the rule will not have a significant economic impact on a substantial
number of small entities. During such a Panel process, the agency would gather information and
recommendations from Small Entity Representatives (SERs) on how to reduce the impact of the
rule on small entities. As discussed below, the EPA is certifying that this proposed rule will not
have a significant economic impact on a substantial number of small entities, and thus the
Agency has not conducted an SBAR Panel for this rulemaking. The following discussion
provides an overview of small entities in the vehicle market. Small entities include small
businesses, small organizations, and small governmental jurisdictions. For the purposes of
assessing the impacts of the rule on small entities, a small entity is defined as: (1) a small
business that meets the definition for business based on the Small Business Administration's
(SBA) size standards (13 CFR §121.201 2026), (2) a small governmental jurisdiction that is a
government of a city, county, town, school district, or special district with a population of less
than 50,000; and (3) a small organization that is any not-for-profit enterprise which is
independently owned and operated and is not dominant in its field.
The EPA is certifying that this proposed rule will have no significant economic impact on a
substantial number of small entities (No SISNOSE). The EPA has focused the Agency's
assessment of potential small business impacts on two key aspects of the standards, including
criteria pollutant NMOG+NOx fleet average standards and PM emissions standards.
The EPA has evaluated the potential impacts on small entities (as well as small volume
manufacturers) of a delay in the 2027 and 2028 criteria pollutant emissions standards, including
both the NMOG+NOx standard and the PM standard. Under the current light-duty and medium-
duty vehicle program, small entities are not subject to any phase-in requirements in 2027 and
2028. The phase-in for small volume manufacturers, which produce both BEV and conventional
ICE products, is 0 percent from 2027 to 2031, (thus no action is required in 2027 and 2028) and
rises to 100 percent in 2032.
Many of the current small entity manufacturers produce BEVs which have no tailpipe
emissions and therefore would inherently comply with the standards. These entities may have
generated NMOG+NOx emission credits in 2027 and 2028; however, since all manufacturers are
exempt from the 2027 and 2028 standards, there are no disparate impacts on small entity and/or
small volume manufacturers.
4-1
-------
Chapter 4 References
13 CFR §121.201. 2026. https://www.ecfr.gov/current/title-13/chapter-I/part-121/subpart-
A/subj ect-group-ECFRf 12all421b08a31/section-121.201.
4-2
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