FACT SHEET
Final Rule:

Revised Cross-State Air Pollution Rule Update
for the 2008 Ozone NAAQS

SUMMARY OF ACTION

On March 15, 2021, EPA finalized the Revised Cross-State Air Pollution Rule (CSAPR)
Update in order to resolve 21 states' outstanding interstate pollution transport
obligations for the 2008 ozone National Ambient Air Quality Standards (NAAQS).

Starting in the 2021 ozone season, this final rule will reduce emissions of nitrogen oxides
(NOx) from power plants in 12 states, improving air quality for millions of Americans.

This rulemaking responds to a September 2019 ruling by the United States Court of
Appeals for the D.C. Circuit, Wisconsin v. EPA, which remanded the 2016 CSAPR Update
to EPA for failing to fully eliminate significant contribution to nonattainment and
interference with maintenance of the 2008 ozone NAAQS from these states by
downwind areas' attainment dates.

Cross-State Air Pollution Rule Regions



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CSAPR Ozone Season NOx Programs

Original CSAPR (Group 1)
^ CSAPR Update (Group 2)
I Revised CSAPR Update (Group 3)

KEY FEATURES

Meets Clean Air Act "good neighbor" obligations for the 2008 ozone NAAQS

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This action fully resolves 21 states' remaining "good neighbor" obligations under the
2008 ozone NAAQS.

For 9 out of the 21 states for which the CSAPR Update was previously found to be only a
partial remedy (Alabama, Arkansas, Iowa, Kansas, Mississippi, Missouri, Oklahoma,
Texas, and Wisconsin), projected 2021 emissions do not significantly contribute to
nonattainment or maintenance problems for the 2008 ozone NAAQS in downwind
states. Thus, no further emission reductions beyond those under the CSAPR Update are
required for these states to address interstate air pollution under the 2008 ozone
NAAQS.

For the 12 remaining states (Illinois, Indiana, Kentucky, Louisiana, Maryland, Michigan,
New Jersey, New York, Ohio, Pennsylvania, Virginia, and West Virginia), projected 2021
emissions were found to contribute at or above a threshold of 1% of the NAAQS (0.75
ppb) to the identified nonattainment and/or maintenance problems in downwind
states. After further analysis of emission-reduction potential, cost-effectiveness of
controls, and downwind air quality improvement, EPA determined additional emission
reductions relative to the CSAPR Update were necessary from all 12 of these states.

Specifically, emission reductions are required at power plants in these 12 states based
on optimization of existing, already-installed selective catalytic reduction (SCR) and
selective non-catalytic reduction (SNCR) controls beginning in the 2021 ozone season,
and installation or upgrade of state-of-the-art NOx combustion controls beginning in the
2022 ozone season.

EPA is issuing new or amended Federal Implementation Plans (FIPs) for 12 states that
revise state emission budgets that reflect these additional emission reductions
beginning with the 2021 ozone season.

EPA will also adjust these 12 states' emission budgets for each ozone season thereafter
to incentivize ongoing operation of identified emission controls until such time that air
quality projections demonstrate resolution of these states' linkages to downwind
nonattainment and/or maintenance problems for the 2008 ozone NAAQS. As such, this
rulemaking includes adjusting emission budgets for each state for each ozone season for
2021 through 2024. Budgets from 2022 to 2024 are updated to account for known
future unit retirements as well as construction of new units. After the 2024 ozone
season, no further adjustments would be required for the purposes of this rule.

The new requirements for the 12 states to make further emission reductions will take
effect 60 days after publication of the notice of final rulemaking in the Federal Register.
This date is expected to fall before the July 20, 2021 Serious area attainment date for
the 2008 ozone NAAQS. This will enable improvements in downwind ozone and
associated public health benefits by the 2021 ozone season. While the new Group 3
trading program established in the rule will be implemented starting May 1, 2021 (the
first day of the 2021 ozone season), EPA is issuing supplemental allowances to ensure

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that the increased stringency reflected in the new emission budgets will not take effect
before the rule's effective date. The amount of supplemental allowances issued for each
state reflects the difference between the state's budgets under the Group 2 trading
program and the new Group 3 trading program for the portion of the 2021 ozone
season between May 1 and the rule's effective date.

It is important to note that this action is taken only with respect to good neighbor
obligations under the 2008 ozone NAAQS, not the more stringent 2015 ozone NAAQS.
Nonetheless, emission reductions and associated improvements in air quality achieved
in this action are beneficial towards attaining the 2015 ozone NAAQS.

Utilizes a proven, achievable, and cost-effective mechanism

Under this rulemaking, FIPs will require power plants in the 12 linked states to
participate in a new CSAPR NOx Ozone Season Group 3 Trading Program that largely
replicates the existing CSAPR NOx Ozone Season Group 2 Trading Program, with the
main differences being the geography and emission budget stringency. Aside from the
removal of the 12 covered states from the current CSAPR NOx Ozone Season Group 2
Trading Program, this rule leaves unchanged the emission budget stringency and
geography of the existing CSAPR NOx Ozone Season Group 1 and Group 2 Trading
Programs.

This rule includes two mechanisms to facilitate implementation and promote
compliance flexibility, while maintaining the environmental protection provided by the
program:

•	First, EPA is creating a limited initial bank of allowances for use in the new Group
3 trading program. Certain allowances banked in 2017-2020 under the existing
Group 2 trading program will be converted at a ratio of 8:1 up to the initial
Group 3 bank target amount.

•	Second, additional Group 3 allowances are available as a "safety valve" for the
2021 control period. Sources can create an additional limited number of Group 3
allowances through the voluntary conversion of additional banked 2017-2020
Group 2 allowances at an 18:1 ratio.

This final rule does not include limits on ozone season NOx emissions from non-EGU
sources. Using the best information currently available to the Agency, EPA determined
that there are relatively fewer emission reductions available from the non-EGU controls
EPA evaluated at a cost threshold comparable to the cost threshold selected for EGUs.
Such reductions are estimated to have a much smaller effect on any downwind receptor
in the year by which EPA finds such controls could be installed. For these reasons, EPA
concluded that limits on NOx emissions from non-EGUs are not required to eliminate
significant contribution or interference with maintenance under the 2008 ozone NAAQS.

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EPA is also finalizing an error correction of its June 2018 approval of Kentucky's good
neighbor state implementation plan (SIP), which had concluded that the CSAPR Update
was a complete remedy based on modeling of the 2023 analytic year. The basis for that
conclusion was invalidated by the decisions in Wisconsin v. EPA and New York v. EPA
(which vacated a similar set of findings in a rule called the "CSAPR Close-out"). With
finalization of this error correction and disapproval of Kentucky's SIP, Kentucky's good
neighbor obligations would be outstanding, but are now resolved along with the other
20 states' in this rulemaking.

BENEFITS AND COSTS OF EMISSION REDUCTIONS

Ozone is linked to a variety of serious public health effects. Exposure to ozone can harm
the respiratory system (the upper airways and lungs) and aggravate asthma and other
lung diseases. Evidence indicates ozone also is likely to be one of the many causes of
asthma development. Exposure to ozone is linked to early death from respiratory and
cardiovascular causes.

Emissions of NOx can react with emissions of other "ozone precursors" (such as volatile
organic compounds) in the atmosphere to create ground-level ozone pollution, or smog.
These pollutants can travel great distances, often crossing state lines and making it
difficult for some states to meet or maintain the national clean air standards that
protect public health and welfare. Reducing transport of these pollutants across state
borders would help downwind states meet and maintain the health-based NAAQS for
ozone.

In March 2008, to better protect the health and welfare of Americans, EPA strengthened
the national air quality standards for ozone by setting an 8-hour standard at 75 parts per
billion (ppb) - and, among other things, triggered states' obligation to reduce
transported pollution that could affect downwind areas' ability to meet the standard.

Reducing the transport of ozone season NOx pollution that crosses state borders will
help downwind states meet and maintain these standards. EPA estimates the Revised
CSAPR Update will reduce summertime NOx emissions from power plants in the 12
linked upwind states by 17,000 tons in 2021 compared to projections without the rule.
Due to this rule and other changes already underway in the power sector, ozone season
NOx emissions will be nearly 25,000 tons lower in 2021 than in 2019, a reduction of 19
percent. The reduction in emissions is estimated to prevent about 290,000 asthma
events, 560 hospital and emergency room visits, 110,000 days of missed work and
school, and up to 230 premature deaths in 2025. The public health and climate benefits
are valued, on average, at up to $2.8 billion each year over the period 2021 to 2040.

These emission reductions will also improve visibility in national and state parks and
benefit sensitive ecosystems including Adirondack lakes and Appalachian streams,
coastal waters and estuaries, and forests.

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The annualized costs of the rule are, on average, $25 million each year over the same
period from 2021 to 2040.

BACKGROUND

The Clean Air Act's "good neighbor" provision (42 U.S.C. § 7410(a)(2)(D)(i)(l)) requires
states to address interstate transport of air pollution that affects the ability of
downwind states to attain and maintain clean air standards. The "good neighbor"
provision requires states to submit State Implementation Plans, or SIPs, that eliminate
pollution that contributes significantly to nonattainment or interferes with maintenance
of the NAAQS in other states. The Clean Air Act requires EPA to issue Federal
Implementation Plans, or FIPs, to address this type of interstate pollution in the event
that states do not submit approvable SIPs. The final Revised CSAPR Update fulfills this
backstop role.

This rule continues EPA's efforts since the 1990s to address interstate pollution, through
rules such as the NOx SIP Call (1998) and the Clean Air Interstate Rule (2005). More
recently, in 2011, EPA finalized CSAPR to address "good neighbor" obligations for the
1997 ozone NAAQS and the 1997 and 2006 fine particle NAAQS. Building on the
methodology of prior rules, CSAPR employed a 4-step framework to address the
requirements of the good neighbor provision for ground-level ozone NAAQS:

•	Identifying downwind receptors that are expected to have problems attaining or
maintaining the NAAQS;

•	Determining which upwind states contribute to these identified problems in
amounts sufficient to "link" them to the downwind air quality problems (i.e.,
here, a one percent contribution threshold);

•	For states linked to downwind air quality problems, identifying upwind emissions
that significantly contribute to downwind nonattainment or interfere with
downwind maintenance of the NAAQS; and

•	For states that are found to have emissions that significantly contribute to
nonattainment or interfere with maintenance of the NAAQS downwind,
implementing the necessary emission reductions through enforceable measures.

In October 2016, EPA finalized the CSAPR Update to address summertime transport of
ozone for the 2008 ozone NAAQS and updated the CSAPR ozone season program. The
CSAPR Update issued new and revised FIPs for 22 states in the eastern U.S. Based on
information available at that time, EPA could not conclude that the rule fully addressed
good neighbor obligations for 21 of the 22 CSAPR Update states (for Tennessee, the
CSAPR Update was a full remedy).

In December 2018, EPA finalized the CSAPR Close-Out. Based on modelling, EPA
projected that in 2023 there would be no remaining nonattainment or maintenance
receptors in the eastern U.S. Thus, EPA determined that the CSAPR Update fully
addressed interstate pollution transport obligations under the 2008 NAAQS for ozone in
20 eastern states.

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On September 13, 2019, the United States Court of Appeals for the District of Columbia
Circuit (DC Circuit) remanded the CSAPR Update in Wisconsin v. EPA, concluding that it
unlawfully failed to eliminate significant contribution to nonattainment and interference
with maintenance by downwind areas' attainment deadlines for the 2008 NAAQS.

On October 1, 2019, the DC Circuit in New York v. EPA vacated the CSAPR Close-Out on
the same grounds that it remanded the CSAPR Update in Wisconsin v. EPA. Specifically,
the Close-Out Rule analyzed the year 2023 as opposed to 2021, the next applicable
attainment date for the 2008 ozone NAAQS, and failed to demonstrate that it was
impossible to address significant contributions by the 2021 attainment date.

Today's final rule is in response to these decisions and fully resolves the outstanding
good neighbor obligations at issue, in compliance with the holdings in these cases.

The proposed Revised CSAPR Update was signed on October 15, 2020 and published in
the Federal Register on October 30, 2020. EPA held a public hearing on November 12,
2020, and the public comment period for the proposal was open through December 14,
2020. The EPA received approximately 80 comments on the proposal and considered
these comments as we developed this final rule. The preamble for the final rule
addresses many of these comments, and EPA's responses to the remaining comments
can be found in a "response to comments" document located in the docket for this
action.

FOR MORE INFORMATION

To read or download a copy of the final rule, go to https://www.epa.gov/csapr/revised-
cross-state-air-pollution-rule-update or http://www.regulations.gov. The final rule will
also be available in hardcopy at the EPA Docket Center's Public Reading Room, subject
to ongoing restrictions related to COVID-19. Materials for this final action can be
accessed using Docket ID No. EPA-HQ-OAR-2020-0272.For further information about the
final action, contact Daniel Hooper of EPA's Office of Atmospheric Programs, Clean Air
Markets Division, at 202-343-9167 or by e-mail at hooper.daniel@epa.gov.

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