Final Determination for Renewable Fuels
and Air Quality Pursuant to Clean Air
Act Section 211(v)
oEPA
United States
Environmental Protection
Agency

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Final Determination for Renewable Fuels
and Air Quality Pursuant to Clean Air
Act Section 211(v)
Assessment and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
United States
Environmental Protection
^1	Agency
EPA-420-R-21-002
January 2021

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Final Determination for Renewable Fuels and Air Quality
Pursuant to Clean Air Act Section 211(v)
Summary
EPA has determined that no additional fuel control measures are necessary under Clean
Air Act section 21 l(v) to mitigate adverse air quality impacts of required renewable fuel
volumes.
Introduction
The Renewable Fuel Standard (RFS) program (Clean Air Act (CAA) section 21 l(o)) was
created by the Energy Policy Act of 2005 (EPAct) and expanded by the Energy Independence
and Security Act (EISA) in 2007. The RFS program was designed to "increase the production of
clean renewable fuels" by requiring increasing volumes of renewable fuel to be introduced into
the United States' supply of transportation fuel.1
The amendments added by EISA included section 21 l(v) of the CAA, which requires
EPA to take two actions. First, section 21 l(v) states that:
the Administrator shall complete a study to determine whether the renewable fuel
volumes required by this section will adversely impact air quality as a result of changes
in vehicle and engine emissions of air pollutants regulated under this chapter.
This study, commonly known as the "anti-backsliding study," must include consideration of
different blend levels, types of renewable fuels, and available vehicle technologies, as well as
appropriate national, regional, and local air quality control measures, according to section
21 l(v)(l)(B). EPA has completed the required study,2 and it is described in further detail below.
Second, section 21 l(v) states that:
the Administrator shall—
(A)	promulgate fuel regulations to implement appropriate measures to mitigate, to the
greatest extent achievable, considering the results of the study under paragraph (1), any
adverse impacts on air quality, as the result of the renewable volumes required by this
section; or
(B)	make a determination that no such measures are necessary.
1	Pub. L. No. 110-140, §§ 201-202, 121 Stat. 1492, 1492 (2007).
2	Report No. EPA-420-R-20-008. Available at https://www.epa.gov/renewable-fuel-standard-program/anti-
backsliding-determination-and-studv.
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The general purpose of this provision prompts EPA to study and address, as appropriate,
potential adverse effects on air quality caused by the implementation of the RFS program. In
fulfilling its obligation under this section, EPA has had to exercise its technical judgment in
designing the anti-backsliding study, in assessing the results, and in determining a course of
action. We describe below, and in the study, the judgments we made and the conclusions we
reached.
In addition, EPA interprets section 211 (v) as providing authority to take action to
mitigate any adverse impacts of the RFS program subject to two crucial limitations established
by section 211 (v) (2). First, EPA may only promulgate "fuel regulations" in response to any
adverse impacts, which narrows the range of possible regulatory actions (section 211 (v) (2) (A)).
While EPA retains broad discretion to regulate vehicle emissions under section 202, and is
considering the mitigating impacts of certain vehicle standards adopted since the enactment of
Sections 211 (o) and 211 (v), EPA is not directed to do so to mitigate any adverse impacts of the
RFS program resulting from changes in vehicle and engine emissions. Second, EPA must only
promulgate such fuel regulations if the agency believes they are appropriate measures necessary
to mitigate any adverse impacts of the RFS program (section 211(v)(2)(A)-(B)). If there are no
necessary, appropriate measures, EPA is not directed to promulgate regulations.
These limitations also serve to highlight the role of EPA's technical judgment under
section 211 (v) (2). The measures that EPA puts in place must be "appropriate." As the Supreme
Court has stated, the "term [appropriate] leaves agencies with flexibility," although agencies
must consider "all the relevant factors" when deciding whether regulation is "appropriate,"
including the cost of those regulations.3 To comply with section 211 (v) (2), then, EPA must
consider whether there are any potential fuel regulations that are both "necessary" to mitigate
adverse impacts of the RFS program as a result of the renewable volumes required by section
211 (o) and are "appropriate" measures to do so. On June 8, 2020, EPA announced its proposed
determination that there are no fuel regulations that are both "necessary" and "appropriate" to
mitigate any of the adverse impacts identified after consideration of the section 211 (v) (1) study
discussed further below. After considering public comments, EPA is now finalizing that
determination.
Section 211 (o) lays out the renewable fuel volume requirements for the RFS program,
which are designed to increase over time. For total renewable fuel, the CAA establishes
increasing annual nationally applicable volume targets through 2022 (section 211 (o) (2) (B) (i) (I)).
However, Congress authorized EPA to reduce those statutory volumes in limited circumstances.
First, if EPA's projection of cellulosic biofuel production is lower than the statutory volume laid
out in section 211 (o) (2) (B) (i) (III), EPA must lower the cellulosic biofuel volume, and has broad
discretion to decide whether to lower the applicable volume for advanced and total renewable
fuel as well (section 211 (o) (7) (D) (i)) ,4 Second, if EPA determines there is "inadequate domestic
supply" or the volumes "would severely harm the economy or environment of a State, a region,
or the United States," then EPA may exercise its discretion to lower the required volumes
3Michigan v. EPA, 135 S.Ct. 2699, 2707 (2015).
4 Cellulosic biofuels are a subset of advanced and total renewable fuel. See 211 (o) (1) (E).
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(section 211(o)(7)(a)). Those two authorities are often known as the "cellulosic waiver
provision" and the "general waiver provision," respectively.
From 2010 to 2019, EPA has exercised one or both of its waiver authorities, replacing the
volumes in the statutory table with new required total renewable fuel volumes.5 The statute
requires EPA to analyze the impacts of "the renewable fuel volumes required by this section."
This phrase could refer to the statutory volumes set forth in CAA section 211 (o) (2) (B) or to the
volumes actually used in calculating the percentage standards under section 211 (o) (3) (B) which
apply to obligated parties and result in renewable fuels being used in transportation fuels. EPA
notes that actual volumes have fallen well short of the statutory volumes6 and concludes it is
more reasonable and appropriate to use the volumes which represent actual fuel consumed and
actual impacts on emissions to the air, rather than hypothetical statutory volumes. Thus, EPA
completed the antibacksliding study by comparing the volumes of renewable fuel actually used
under the RFS to the volumes of renewable fuel in the fuel supply before the RFS program was
implemented.7
In particular, EPA chose to use 2016 as the year for assessing the effects on air quality of
renewable fuel volumes. EPA compared two scenarios for calendar year 2016, one with actual
renewable fuel volumes (the "with-RFS" scenario) and another with renewable fuel use
approximating 2005 levels (the "pre-RFS" scenario). By analyzing calendar year 2016, EPA
was able to use an existing modeling platform that includes known renewable fuel volumes and
fuel properties based on actual data. The "pre-RFS" scenario used 2005 renewable fuel usage,
because that is the year EPAct was signed into law. Other potential study approaches would have
involved highly uncertain estimates of fuel volumes and would have been less informative.
By analyzing calendar year 2016, EPA was also able to analyze a year where the non-
cellulosic renewable fuel volumes (e.g., ethanol and biodiesel volumes) were substantially
phased in and not dramatically different from today's volumes. In keeping with this, the "with-
RFS" scenario assumed 10 percent ethanol (E10) was used nationwide in all onroad and nonroad
gasoline-fueled vehicles and engines, and biodiesel was used at a five percent blend (B5) in all
onroad diesel vehicles nationwide. This was compared to the "pre-RFS" scenario, which
assumed E10 usage only in the 2016 reformulated gasoline (RFG) areas and no biodiesel usage.
Fuels in California were assumed to be the same in both scenarios. Consistent with the statutory
focus on the impact of renewable fuel volumes on "changes in vehicle and engine emissions of
air pollutants," EPA only varied the fuel supplies for onroad and nonroad engines between the
5	75 FR 14670 (March 26, 2010), 75 FR 76790 (December 9, 2010), 77 FR 1320 (January 9, 2012), 78 FR 49794
(August 15, 2013), 79 FR 25025 (May 2, 2014), 80 FR 77420 (December 14, 2015), 81 FR 89746 (December 12,
2016), 82 FR 58486 (December 12, 2017), 83 FR 63704 (December 11, 2018), 85 FR 7016 (February 6, 2020).
6	The shortfall has been primarily in the mandated cellulosic volumes which have remained a very small fraction of
the statutory volumes and the vast majority of which has been biogas replacing fossil natural gas, not liquid fuels
replacing gasoline or diesel fuel.
7	Report No. EPA-420-R-20-008. Available at https://www.epa.gov/renewable-fuel-standard-program/anti-
backsliding-determination-and-studv.
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two scenarios—everything else, including "upstream" emissions from producing, storing, and
transporting fuels and feedstocks, was held constant in both scenarios at 2016 levels.8
The study assessed the changes in emissions from motor vehicles and nonroad engines
and equipment using the MOtor Vehicle Emission Simulator (MOVES). Air quality modeling
was done using the Community Multiscale Air Quality model (CMAQ) to estimate the resulting
impacts on concentrations of ozone, particulate matter (PM), nitrogen dioxide (NO2), carbon
monoxide (CO), and some air toxics (including acetaldehyde, acrolein, benzene, 1,3-butadiene,
formaldehyde, and naphthalene).
The results of this analysis were that, compared to the "pre-RFS" scenario, the 2016
"with-RFS" scenario increased ozone concentrations (eight-hour maximum daily average) across
the eastern U.S. and in some areas in the western U.S., with some decreases in localized areas.
In the 2016 "with-RFS" scenario, concentrations of annual average fine particulate matter
(PM2.5) were relatively unchanged in most areas, with increases in some areas and decreases in
some localized areas. The 2016 "with-RFS" scenario increased annual average concentrations of
NO2 across the eastern U.S. and in some areas in the western U.S., with larger increases in some
urban areas. The 2016 "with-RFS" scenario decreased annual average concentrations of CO
across the eastern U.S. and in some areas in the western U.S., with larger decreases in some
areas.
Compared to the "pre-RFS" scenario, the 2016 "with-RFS" scenario increased annual
average concentrations of acetaldehyde across much of the eastern U.S. and some areas in the
western U.S. and resulted in widespread increases in annual average formaldehyde
concentrations. The 2016 "with-RFS" scenario decreased annual average benzene
concentrations across most of the U.S., as compared to the "pre-RFS" scenario. The 2016 "with-
RFS" scenario also resulted in decreased annual average concentrations of 1,3-butadiene in many
urban areas. The 2016 "with-RFS" scenario resulted in small, geographically limited increases
and decreases in annual average concentrations of acrolein and naphthalene.
Necessity and Availability of Appropriate Control Measures to Address Modeled
Adverse Impacts
Having characterized the potential adverse impacts of the renewable fuel volumes
required by the RFS, we next considered whether it is necessary to implement appropriate fuel
control measures to address those impacts. First, we examined the impact of the Tier 3 motor
vehicle emissions and fuel standards, promulgated in 2014.9 These standards post-date the
adoption of the RFS and section 211 (v) and likewise are not reflected in the antibacksliding
study's comparison of "pre-RFS" to "with-RFS" scenarios. The Tier 3 sulfur standard was
implemented in 2017, and the vehicle standards are phasing in between 2017 and 2025. Benefits
8	More explanation of the assumptions, their rationale, and the potential impacts on the results can be found in the
Clean Air Act Section 211(v)(l) Anti-backsliding Study, EPA-420-R-20-0008. Available at
https://www.epa.gov/renewable-fuel-standard-program/anti-backsliding-determination-and-studv.
9	Control of Air Pollution from Motor Vehicles: Tier 3 Motor Vehicle Emission and Fuel Standards, 79 FR 23414 (April 28,
2014). Although these standards were authorized under section 202 and 211 of the Clean Air Act, they were not adopted to fulfill
any specific statutory direction.
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of the vehicle standards will further increase over time as the fleet turns over. The Tier 3 rule
imposes fleet-wide exhaust emission standards for non-methane organic gases (NMOG) and
nitrogen oxides (NOx) that are 80% lower than the previous standards; PM exhaust emissions
standards for light and medium-duty vehicles that are 70% lower than previous standards; and
standards for heavy-duty pick-ups and vans that are on the order of 60% lower than previous
standards. It also imposes tighter evaporative emission standards for gasoline-powered vehicles
that represent a 50% reduction from previous standards. The tighter exhaust standards are
enabled by gasoline sulfur reductions of over 60%, allowing for more efficient and durable
emission control systems. The Tier 3 motor vehicle emission and fuel standards require recent
advances in vehicle and refining technology to be broadly applied across the industries. The
vehicle emission standards combined with the reduction of gasoline sulfur content are reducing
motor vehicle emissions, including nitrogen oxides (NOx), volatile organic compounds (VOC),
direct particulate matter (PM2.5), carbon monoxide (CO) and air toxics. Significantly, EPA
changed the longstanding primary certification fuel for light-duty vehicles from non-oxygenated
gasoline (E0) to gasoline containing 10 percent ethanol (E10) to better match in-use fuel after
implementation of the RFS program. In this way, the Tier 3 program was designed to control
vehicle emissions taking into consideration the nationwide shift to E10 under the RFS program.
A comparison of the air quality impacts estimated by the anti-backsliding study for 2016
and the Tier 3 regulatory analysis for 2018 and 2030 demonstrates the mitigating impact of the
Tier 3 program. Our comparison uses maps to depict the impacts modeled in the anti-
backsliding study and the impacts modeled for the Tier 3 rule. Although there are differences in
modeling assumptions between the two analyses, they are similar enough to allow meaningful
comparisons. For example, while the Tier 3 rule relied on a modified version of MOVES2010,10
the fuel effects updates in that Tier 3 model were incorporated into MOVES2014, giving similar
results for fuel impacts. Also, while Tier 3 was modeled using the NONROAD model, the data
and algorithms used were largely unchanged in the version of NONROAD incorporated in
MOVES2014, and the fuel effects are the same.
Table 1 compares key modeling assumptions in the two efforts.11,12¦13 Furthermore, the
limitations noted in the anti-backsliding study—including lack of data on spatial distribution of
biodiesel use, limited data on effects of renewable fuels on nonroad engines, uncertainties in
hydrocarbon speciation, and uncertainties in photochemical mechanisms used in CMAQ—are
similar for both analyses.14 The methodological differences and limitations of the analyses are
10	U.S. EPA. 2014. "Memorandum to Docket: Updates to MOVES for the Tier 3 FRM Analysis" Docket No. EPA-
HQ-OAR-2011-0135.
11	Report No. EPA-420-R-20-008. Available at https://www.epa.gov/renewable-fuel-standard-program/anti-
backsliding-determination-and-studv.
12	U. S. EPA. Emissions Modeling Technical Support Document: Tier 3 Motor Vehicle Emission and Fuel Standards. Air Quality
Assessment Division, Office of Air Quality Planning and Standards, Research Triangle Park, NC. Report No. EPA-454/R-14-
003, February 2014.
13	U. S. EPA. Air Quality Modeling Technical Support Document: Tier 3 Motor Vehicle Emission and Standards. Air Quality
Assessment Division, Office of Air Quality Planning and Standards, Research Triangle Park, NC. Report No. EPA-454/R-14-
002, February, 2014. Available at https://nepis.epa.gov/Exe/ZvPDF.cgi/P100HX23.PDF?Dockev=P 100HX23.PDF
14	Report No. EPA-420-R-20-008. Available at https://www.epa.gov/renewable-fuel-standard-program/anti-
backsliding-determination-and-studv.
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not significant enough to change a conclusion that the Tier 3 standards mitigate the air quality
impacts of renewable fuel volumes suggested by the anti-backsliding study.
Table 1. Air Quality Modeling Assumptions for Anti-backsliding Study and Tier 3 Rule

Anti-Backsliding Study
Tier 3 Rule
Mobile Source Inventory
Onroad and Nonroad:
MOVES2014b
Onroad: MOVES 2010b with
fuel effects updates; Nonroad:
National Mobile Inventory
Model, version
NMIM20090504a
Air Quality Model
CMAQ version 5.2.1
CMAQ version 5.0.1
Modeling Platform15
2016 Version 7.2
2007/8 Version 5
Grid Resolution
12 km, with 36 km for
boundary conditions
12 km, with 36 km for
boundary conditions
Scenarios Compared
2016 with actual fuel
volumes under RFS; 2016
with renewable fuel usage at
2005 levels (before RFS)
2018 with and without Tier 3
fuel and vehicle standards;
2030 with and without Tier 3
fuel and vehicle standards
Meteorological Inputs
Weather Research and
Forecasting Model (WRF)
version 3.8
Weather Research and
Forecasting Model (WRF)
version 3.3
Figures 1 through 15 below depict comparisons in absolute changes in concentrations of
ozone, PM2.5, NOx, acetaldehyde, and formaldehyde. Changes in absolute levels of acrolein and
naphthalene are not shown as they do not show up within the resolution of the smallest scale on
the maps.
Figures 1 through 3 show the offsetting impacts of the anti-backsliding study and Tier 3
for annual 8-hour maximum daily average ozone. The largest ozone increases identified by the
anti-backsliding study occur in the Southeast, with increases ranging from 0.25 to 0.75 ppb, with
a few locations over 0.75 ppb. However, decreases due to Tier 3 largely offset these increases in
2018, and by 2030 fully offset the increases at the vast majority of locations across the U.S.
Figures 4 through 6 show the offsetting impacts for annual average PM2.5. The anti-backsliding
study identifies small increases in PM2.5 at a few locations in the Pacific Northwest; these
increases range from 0.01 to 0.05 [^g/m3. However, decreases due to Tier 3 largely offset these
increases in 2018, and more than offset them by 2030. Figures 7 through 9 show the offsetting
impacts for annual average NO2. While the anti-backsliding study identifies NO2 increases up to
0.3 ppb, reductions from Tier 3 are substantially larger by 2030. Calendar year 2030 is an
appropriate year of focus, because any new program EPA could promulgate under section 211 (v)
would likely not be implemented until at least 2025, given the need for lead time.
https://www.epa.gov/air-emissions-modeling/emissions-modeling-platforms
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The anti-backsliding study identified increases in formaldehyde concentrations in many
locations; however, reductions due to Tier 3 standards will offset these increases (Figures 13-15).
In contrast, in many locations Tier 3 standards will not fully offset the acetaldehyde increases
identified in the anti-backsliding study (Figures 10-12). Acetaldehyde is a primary byproduct of
the combustion of ethanol, which is the primary renewable fuel increased in the marketplace as a
result of section 211 (o) implementation. EPA is not aware of a fuel control that would address
this pollutant without reducing ethanol use. Requiring reductions in ethanol use under section
211 (v) would run directly counter to meeting the renewable fuel requirement of section 211 (o).
Section 211 (v) only seeks mitigation of the air quality impacts of the renewable fuel volumes
required under 211 (o), not the reversal of those volumes. Moreover, EPA has already taken
action with the Tier 3 standards to broadly reduce pollutants to the extent technologically
achievable, and EPA is not aware of any vehicle or engine emissions control technology that
could specifically target acetaldehyde further.
Conclusion and Final Determination
Based on the results of the antibacksliding study, considered in conjunction with
pollution control measures EPA has already adopted and its evaluation of additional fuel control
measures that are currently available, EPA has determined that no additional fuel control
measures are necessary to mitigate adverse air quality impacts of required renewable fuel
volumes. The Tier 3 rule has been promulgated and implemented, and these actions include fuel
and vehicle standards that reflect the shift of the gasoline pool from E0 to E10 while reducing
concentrations of ozone, PM2.5, NO2, and air toxics now and in the future. The analyses
supporting Tier 3 predict widespread reductions in 2018 and 2030 in ozone, PM, NO2, and
toxics, which mitigate the potential adverse air quality impacts identified in the anti-backsliding
study. For PM2.5, reductions from Tier 3 by 2030 are substantially larger than any adverse
impacts modeled in the anti-backsliding study. For other pollutants except acetaldehyde, Tier 3
reductions fully offset any adverse impacts from the anti-backsliding study at the vast majority of
locations across the U.S.
Therefore, based on these comparisons, and the lack of available controls which
specifically target acetaldehyde, EPA concludes that there are no additional appropriate measures
which are necessary to mitigate the potential adverse air quality impacts of required renewable
fuel volumes.
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ppb
< -0.75
-0.75 to -0.50
-0.50 to -0.25
-0.25 to -0.10
-0.10 to 0.10
0.10 to 0.25
0.25 to 0.50
0.50 to 0.75
> 0.75
Figure 1. Change in absolute concentrations of 8-hour maximum daily average 2016 ozone
between "pre-RFS" and "with-RFS" scenarios
Difference In Annual Gradient-Adjusted 6-hr O2
20lSrt)_cll minus 20ltrg_
Figure 2. Change in absolute concentrations of 8~hour maximum daily average ozone in 2018,
with and without Tier 3 standards
Figure 3. Change in absolute concentrations of 8-hour maximum daily average ozone in 2030,
with and without Tier 3 standards
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.la* O.C.,1 Mn:-0
ug/m3
< -0.25
-0.25 to -0.10
-0.10 to -0.05
-0.05 to -0.01
-0.01 to 0.01
0.01 to 0.05
0.05 to 0.10
> 0.10
Figure 4. Absolute change in average annual 2016 PM2.5 concentrations between "pre-RFS" and
"with RFS" scenarios
-0.25 ug/m3
>= -0.25 to < -0.1
>= -0.1 to < -0.05
>= -0.05 to < -0.01
>= -0.01 to <= 0.0
0.0 to <= 0.01
0.01 to <= 0.05
0.05 to <= 0.1

Figure 5. Change in absolute concentrations of annual average PM2.5 in 2018, with and without
Tier 3 standards
Figure 6. Change in absolute concentrations of annual average PM2.5 in 2030, with and without
Tier 3 standards
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(!§	"7;


1
iPp^
7 ¦ .. •• -  0.30
Figure 7. Absolute change in average annual 2016 NO2 concentrations between "pre-RFS" and
"with-RFS" scenarios
1 TofaJ NO! Concentration

Figure 8. Change in absolute concentrations of average NCbin 2018, with and without Tier 3
standards
Figure 9. Change in absolute concentrations of average NO2 in 2030, with and without Tier 3
standards
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% \

ug/m3
< -0.300
-0.300 to -0.200
-0.200 to -0.100
-0.100 to -0.010
-0.010 to -0.001
-0.001 to 0.001
0.001 to 0.010
0.010 to 0.100
0.100 to 0.200
0.200 to 0.300
> 0.300

Figure 10. Absolute change in average annual 2016 acetaldehyde concentrations between "pre
RFS" and "with-RFS" scenarios
Figure 11. Change in absolute concentrations of annual average acetaldehyde in 2018, with and
without Tier 3 standards
Figure 12. Change in absolute concentrations annual average acetaldehyde in 2030, with and
without Tier 3 standards
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ft
ug/m3
< -0,300
-0.300 to -0.200
-0.200 to -0.100
-0.100 to -0.010
-0.010 to -0.001
-0.001 to 0.001
0.001 to 0.010
0.010 to 0.100
0.100 to 0.200
0.200 to 0.300
> 0.300
Figure 13. Absolute change in average annual 2016 formaldehyde concentrations between "pre
RFS" and "with-RFS" scenarios
Absolute Difference tor Formaldehyde -Aiiim.it
2018rg_cll minus 201Srg_ret2
Figure 14. Change in absolute concentrations of annual average formaldehyde in 2018, with and
without Tier 3 standards
Absolute Difference for I
Figure 15. Change in absolute concentrations of annual average formaldehyde in 2030, with and
without Tier 3 standards
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APPENDIX: Response to Comments
Comment: Commenter argues that the fact that Tier 3 is improving air quality doesn't satisfy
EPA's statutory duty to mitigate the adverse impacts of renewable fuels under CAA section
211 (v) (2). The commenter states that the "required inquiry under section 211 (v) is whether
required renewable fuel volumes adversely impact air quality." The commenter claims that
reductions in air pollution due to the Tier 3 regulation "do not impact the adverse air quality
impacts that occur 'as the result of the renewable volumes required by [section 211]."' Even if
air quality impacts from the transportation sector may be otherwise improving, the commenter
claims that EPA retains a duty under CAA section 211 (v) to promulgate appropriate measures to
mitigate the additional difference in air quality from the use of renewable fuels. Commenter
further states, "emissions standards under section 202 must comply with the 'greatest degree of
emission reduction achievable . . . giving appropriate consideration to cost, energy, and safety
factors.' As EPA notes, the Tier 3 program took into account the use of renewable fuels in
determining what emissions levels would comply with this standard. But emissions standards
lower than those established by the Tier 3 rule might very well be 'achievable' in the absence of
renewable fuel use."
Response: The EPA disagrees with the view of the section 211 (v) expressed by the
commenter. Under EPA's view of the statute, EPA's duty is to first complete a study to
determine whether the renewable fuel volumes required by CAA section 211 (o) will
adversely impact air quality as a result of changes in vehicle and engine emissions of air
pollutants regulated under the Act. Commenter is therefore correct that the initial inquiry
required under the statute is "whether the renewable fuel volumes required by [CAA
section 211] will adversely impact air quality," and EPA did determine that the required
volumes have had some adverse air quality impacts for certain pollutants in some areas of
the country. Some areas of the country have seen some air quality benefits due to those
same volumes.
However, that is not the end of the inquiry. As is laid out in the statutory text, following
completion of the study, EPA is required to promulgate fuel regulations only if there are
"appropriate" measures to mitigate, to the greatest extent achievable, any adverse
impacts, and further, the Agency may determine that no such measures are "necessary."
Both of those terms provide EPA with broad discretion. See Michigan v. EPA, 576 U.S.
743, 752 (2015) (recognizing "capaciousness" of phrase "appropriate and necessary").
As is described in detail in the determination, the Tier 3 rule considered the impact of
E10 as an in-use fuel and largely offsets any adverse impacts from E10 and other
increased renewable fuel, which supports EPA's conclusion that no additional measures
are necessary. Moreover, EPA is not aware of additional fuel controls that would reduce
the remaining impacts, nor did any commenter suggest any such controls for EPA to
evaluate. Commenter's reading of the statute would require EPA to solve a problem that
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it has either already addressed or does not have the statutory authority or technical ability
to address, as explained further below.
Commenter appears to interpret section 211 (v) to require a different analysis.
Commenter would have EPA disregard the reductions in air pollution from the Tier 3 rule
and instead identify and implement different reductions that would be "'achievable' in
the absence of renewable fuel use." As explained in both the proposed and final
determination, however, EPA does not understand section 211(v) as authorizing EPA to
reduce or eliminate the use of renewable fuels to address any air quality impacts from
their use. The statutory volumes in the Renewable Fuel Standard (RFS) program, as
enacted by Congress in CAA section 211 (o), would increase renewable fuel volumes
over time. EPA has specific, limited waiver authorities that authorize the Agency to
change such volumes in CAA section 211 (o) (7) based on clearly articulated statutory
factors. As such, 211 (v) authorizes EPA to identify other necessary, appropriate,
available controls to mitigate (i.e., offset) the effect of renewable fuels rather than
changes to renewable fuel volumes. EPA has identified controls that largely offset the air
quality impacts of renewable fuels (and has explained why it found additional appropriate
measures are not necessary or available). EPA disagrees that the reductions achieved by
the Tier 3 rule should be disregarded, or that it would be appropriate, much less required,
under section 211 (v) to attempt to identify additional reductions which could be achieved
in the absence of renewable fuel use.
To the extent commenter suggests that the Tier 3 rule should have been more stringent,
such a comment is not relevant to the proposed determination.
Comment: Commenter stated that EPA must mitigate "any" adverse impact on air quality, and
Tier 3 does not completely offset the adverse impacts from renewable fuels. Commenter argued
that judicial precedent establishes that the word "any" has an expansive meaning and here that
includes impacts that occur at "whatever time and place." However, the commenter claims, EPA
has observed that decreases in ozone due to implementation of Tier 3 do not completely offset
the increases in all locations in the United States. EPA assumed B5 everywhere and noted this
lack of spatial variability in biodiesel blend level as a limitation; EPA should address the extent
to which geographic variation in biodiesel blend levels may exacerbate air quality impacts in
particular parts of the country.
Response: EPA acknowledges the caselaw holding that the word "any" should be
interpreted "expansive[ly]" when there is "no other reason to contravene the clause's
obvious meaning." New York v. EPA, 443 F.3d 880, 885 (D.C. Cir. 2006) (quoting
Norfolk S. Rwy. Co. v. Kirby, 543 U.S. 14, 31-32
(2004)). EPA examined all of the impacts on air quality, both positive and negative, by
pollutant, across the entire country (at a grid scale of 12 km). However, as is described in
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the determination and previous response, section 211 (v) does not simply direct EPA to
mitigate any adverse impact. Rather CAA section 211 (v) (2) requires EPA to
"promulgate fuel regulations to implement appropriate measures to mitigate, to the
greatest extent achievable, any adverse impacts" of the required renewable fuel volumes,
or else determine that "no such measures are necessary" (emphases added). If EPA
concludes there are no appropriate measures that are necessary, EPA is not directed to
promulgate regulations. And similarly, any measures EPA would consider must only
mitigate such impacts "to the greatest extent achievable." As is outlined in the proposal,
Congress has vested EPA with responsibility to determine whether such regulations are
"necessary" to mitigate the identified adverse impacts and whether there are
"appropriate" measures to do so. EPA's determination follows a technical study prepared
by the Agency and must consider the results of that study. This statutory scheme
highlights the role of EPA's technical judgment under CAA section 211 (v) (2). EPA has
exercised its judgment consistent with the discretion provided by its interpretation of the
statutory text.
As described in the study, while biodiesel use varies across the country, we are not aware
of any data that would allow us to quantify and appropriately allocate varying biodiesel
volumes. Thus, while there may be some differences in the emission impacts of biodiesel
from area to area, it is not something EPA can currently evaluate. Regardless, even if
EPA were able to quantify potential localized adverse impacts, EPA is not aware of any
appropriate fuel control measures to mitigate them, nor did the commenter suggest any. A
more refined analysis of biodiesel air quality impacts would not create new control
measures to evaluate.
Comment: Commenters state that EPA should conduct a prospective analysis (projecting future
impacts of renewable fuel in air quality in coming years and decades), rather than the
retrospective analysis in the anti-backsliding study (assessing impacts of renewable fuel use in
2016). One commenter acknowledges that a retrospective analysis is more reliable but argues
that a prospective analysis is required by statutory language in CAA section 211 (v) (1) (A) ("the
Administrator shall complete a study to determine whether the renewable fuel volumes required
by this section will adversely impact air quality..." (emphasis added)). The commenter notes that
Congress instituted the requirement to conduct the anti-backsliding study in 2007 and required
EPA to complete it within 18 months while at the same time expanding renewable fuel volumes
significantly. The commenter further argues that EPA's delay in issuing the study does not
relieve the Agency from the obligation to account for likely future changes that may affect air
quality impacts from the use of renewable fuels. Another argues that a prospective analysis
makes more sense given that EPA's Tier 3 rule will change the vehicle fleet moving forward,
and the study does not reflect that change. Commenter argues that the fuel effects EPA models
using MOVES 2014b are out of date because they are not based on fuel effects testing of Tier 3
vehicles.
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Response: EPA's decision to base its study on a quantitative analysis of the effects of
actual RFS volumes on air quality in 2016 was a reasonable one. The statute does not
specify how EPA should undertake the study, much less what data EPA must use in
doing the study. There are multiple ways of interpreting the language requiring EPA to
analyze whether the RFS "will adversely impact" air quality. In particular, one
commenter suggests that Congress necessarily intended EPA to examine air quality
impacts that would occur after 2020 (when the study was performed), and not after 2007
(when EISA was adopted) or 2009 (the deadline for performing the study). EPA has
broad discretion both in interpreting section 211 (v) and in deciding how to perform a
technical analysis. EPA determined that a 2016 analysis is reasonable here given the
statutory deadline for the study, EPA's delay in completing it, and the evolution of the
RFS during that time. In addition, EPA judged (and at least one commenter concedes)
that an analysis based on actual, recent data on renewable fuel use would be more reliable
and informative than a study based on projections of future renewable fuel use.
EPA disagrees that section 211 (v) requires EPA to base its study on projections of
renewable fuel use after the date of study, regardless of when the study was completed.
EPA notes that this provision was adopted in the Energy Independence and Security Act
(EISA) as part of a substantial overhaul of the RFS program. As commenters identify,
almost 13 years have passed since Congress passed EISA. As a result, although there are
different potential readings of section 211 (v), EPA finds the best reading is simply that
section 211 (v) directs EPA to determine whether the RFS program, as adopted in EISA,
will adversely affect air quality as a result of changes in vehicle and engine emissions due
to mandated use of renewable fuels. In 2007, or even 2009, such a study would have
involved some projection of future renewable fuel use, because under EISA the volume
of total renewable fuel use was projected to double between 2007 and 2009, and double
again between 2009 and 2016 (and then increase less rapidly). Given this pattern of
increases, and the fact that the volume requirements laid out in the statutory tables in
CAA section 211 (o) (2) (B) (i) span the years 2006 to 2022 (with EPA required to set new
volumes thereafter), if the study had been completed in 2009, EPA may have chosen
2016, or a similar time period, as the basis for analyzing the air quality impacts of the
RFS program.
Congress' use of the phrase "will adversely impact" in 2007 does not require EPA in
2020 to use projected data, and doing so now would have made the study less reliable,
particularly in light of the history of required renewable fuel volumes under the RFS. If
EPA had completed its study by 2009 it would likely have projected volumes (e.g. for
2016) using the volume requirements enshrined in the statutory tables in CAA section
211 (o) (2) (B) (i). In doing so, the study would have significantly overstated actual
required volumes and not reflected the air quality impacts experienced today.
The analysis EPA conducted addresses the question Congress directed EPA to study, but
with the benefit of using actual instead of projected data. As discussed in the proposed
determination, EPA has exercised its waiver authorities every year from 2010 to 2020.
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Actual volumes have fallen well short of the volumes in the statutory tables. In other
words, the volumes analyzed in EPA's anti-backsliding study are vastly different than the
ones Congress originally prescribed. However, Congress established both the statutory
volumes and the waiver authorities and EPA believes the purpose of section 211 (v) is to
study the impacts of the actual volumes on air quality, not the impacts that would have
occurred if EPA had not exercised its waiver authority.
A comparison of the text of section 204 of Energy Independence and Security Act of
2007 (EISA) and the text of CAA section 211 (v) is instructive in discerning Congress's
intent. Both provisions require EPA to develop a study based on its technical expertise
but contain different language, indicating different intended purposes for each report.
Section 204 requires EPA to "assess and report to Congress on the impacts to date and
likely future impacts of the [RFS volume requirements] on" a series of specific
environmental and public health issues every three years. EISA section 204, then, has an
ongoing requirement that clearly and specifically directs EPA to assess both retrospective
and prospective impacts of the volume requirements of the RFS program in each report to
Congress, every three years.
The statutory directive in CAA section 211 (v) (1) differs in two ways: it is designed to be
a one-time analysis of the air quality impacts of the volume requirements of the RFS
program, rather than a periodic assessment, and it uses language that is much less clear
and specific as to the contours of that analysis. Congress intended the 211 (v) (1) study to
be EPA's single best guess as to the air quality impacts of the RFS program based on the
information available at the time of the study's completion. Had Congress intended to
require EPA to consider a particular type of data, either retrospective, prospective, or
both, it could have used more specific language as it did in EISA section 204 ("impacts to
date and likely future impacts"). Instead, Congress simply directed EPA to assess, by a
date certain, whether the then-newly established volumes "will adversely impact" air
quality and left the details up to EPA's discretion.
Thus, EPA believes a study that examines the actual impact of the RFS program
established by EISA on air quality in 2016 fully reflects the Congressional intent for the
study. Moreover, EPA notes that the total renewable fuel volumes established for years
since 2016 have been similar, with small increases, to the volumes established for 2016.
Based on our experience to date in implementing the RFS program, we believe that the
total renewable fuel volumes between now and 2022 are also likely to be generally
similar to volumes from 2016 to now. As a result, EPA believes that near-term future
volumes are unlikely to be different enough from the 2016 case analyzed in the study to
cause any significant changes in the emission and air quality impacts. Moreover, to the
extent that changes in renewable fuel volumes do occur by 2022, or thereafter, that have
material adverse impacts on air quality, we are unable to predict what those changes will
be in light of EPA's ongoing authority and responsibility to adjust the statutory volumes.
See 211 (o) (7); see also 211 (o) (2) (B) (ii). Rather than generate results that would depend
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primarily on assumptions about renewable fuel use in the future, EPA chose to examine
recent data which is reasonably representative of actual renewable fuel under the RFS.
EPA acknowledges the comments that EPA should consider a Tier 3-compliant vehicle
fleet when determining the effects of the RFS program. By considering in its
determination the Tier 3 regulatory analysis, which modeled the vehicle improvements
associated with Tier 3 implementation, EPA does in fact account for the effects of Tier 3
on the impacts that EPA identified in the anti-backsliding study. MOVES2014b was
EPA's most recent publicly available emissions model at the time the anti-backsliding
study was conducted, and its use in the anti-backsliding study remains appropriate and
informative for the purposes of this determination. While EPA agrees that it will be
useful to future modeling efforts to have additional data on the effects of fuel properties
on Tier 3 vehicles, such data is not currently available.
Comment: Commenter argues that Tier 3 standards are a vehicle regulation and do not qualify
as "fuels rulemakings" like what EPA is directed to promulgate under CAA section 211 (v).
Commenter further states that Tier 3 did not give its purpose as mitigating the adverse effects of
potential fuel changes under CAA section 211.
Response: First, EPA's Tier 3 rule was promulgated under both CAA Section 202
(regulating motor vehicle emission standards) and under CAA section 211 (regulating
fuels and fuel additives). Specifically, Tier 3 created gasoline sulfur fuel controls
pursuant to CAA section 211 (c) (1) of the CAA. Commenter's claim that Tier 3 was not a
"fuels rulemaking" is factually incorrect. The Tier 3 rule also changed the certification
test fuel from E0 to E10, under CAA section 206.
Second, the commenter is misapprehending the relevance of Tier 3 to the proposed
determination. EPA is not claiming that Tier 3 is a fuel regulation designed to
"implement appropriate measures to mitigate, to the greatest extent achievable,
considering the results of the study under [CAA section 211 (v) (1) ], any adverse impacts
on air quality" promulgated under CAA section 211 (v) (2) (A). Instead, EPA is noting that
the Tier 3 rule was intended to achieve emissions reductions taking into consideration the
fact that after the RFS was adopted E10 became the most common in-use fuel, and EPA
is taking into consideration the mitigating impacts of those emissions reductions as part
of its determination under CAA section 211 (v) (2) (B) that there are no remaining
"appropriate measuresf.]" In other words, it was reasonable for EPA's CAA section
211 (v) (2) analysis of whether there are "appropriate measures" that are "necessary"
under the statute to take into account the regulatory landscape and the effects other EPA
mobile source regulations are having on emissions from vehicles and engines using
renewable fuels. If EPA had not promulgated the Tier 3 rule, certain measures
promulgated under that rule might have otherwise been appropriate under CAA section
211 (v).
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Comment: There are a number of technical comments related to the anti-backsliding study that
do not have implications for EPA's CAA section 211 (v) (2) determination. For example, some
comments dispute the study's predicted increases in air pollution.
Response: EPA sought comments in the proposal on its "initial determination that there
are no fuel regulations that are both 'necessary' and 'appropriate' to mitigate any of the
adverse impacts identified after consideration of the section 211 (v) (1) study." EPA
appreciates the comments on the anti-backsliding study and intends to consider them as
we consider future improvements to our models and data collection and analysis.
However, EPA is not specifically responding to comments that support EPA's proposed
action but disagree with the study's conclusions on the adverse impacts of renewable
fuels, because these comments do not change EPA's determination under CAA section
211 (v) (2). Such comments are outside the scope of the final determination.
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