Document ID: EPA-HQ-OAR-2020-0037-0001
Agency: epa
Document Type: Notice
Title: Sulfur Dioxide Primary National Ambient Air Quality Standard, 2010: Responses to Certain State Designation Recommendations
Posted Date: 2020-08-21T04:00Z

[Federal Register Volume 85, Number 163 (Friday, August 21, 2020)]
[Notices]
[Pages 51694-51698]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-18129]

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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OAR-2020-0037; FRL-10013-82-OAR]

EPA Responses to Certain State Designation Recommendations for 
the 2010 Sulfur Dioxide Primary National Ambient Air Quality Standard: 
Notice of Availability and Public Comment Period

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of availability and public comment period.

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SUMMARY: Notice is hereby given that the Environmental Protection 
Agency (EPA) has posted our responses to certain state designation 
recommendations for the 2010 Sulfur Dioxide (SO2) Primary 
National Ambient Air Quality Standard (NAAQS) on the Agency's website 
and electronic docket. These responses include our intended 
designations for the affected areas, specifically all remaining 
undesignated areas for the 2010 SO2 NAAQS in the United 
States. The EPA also invites the public to review and provide input on 
our intended designations during the comment period specified in the 
DATES section. The EPA sent its responses directly to the states on or 
about August 13, 2020. The EPA intends to make final designation 
determinations for the areas of the country addressed by these 
responses no later than December 31, 2020.

DATES: Comments must be received on or before September 21, 2020. 
Please refer to SUPPLEMENTARY INFORMATION for additional information on 
the comment period.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2020-0037, at https://www.regulations.gov.\1\ Follow the online 
instructions for submitting comments. Out of an abundance of caution 
for members of the public and our staff, the EPA Docket Center and 
Reading Room are closed to the public, with limited exceptions, to 
reduce the risk of transmitting COVID-19. Our Docket Center staff will 
continue to provide remote customer service via email, phone, and 
webform. We encourage the public to submit comments via https://www.regulations.gov, as there may be a delay in processing mail and 
faxes. Hand deliveries and couriers may be received by scheduled 
appointment only. For further information on EPA Docket Center services 
and the current status, please visit us online at https://www.epa.gov/dockets.
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    \1\ The https://www.regulations.gov platform is in the process 
of being upgraded. Users may be automatically redirected to https://beta.regulations.gov. Both website addresses contain the same 
information and both website addresses allow users to submit 
comments to the docket.
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    Once submitted, comments cannot be edited or removed from 
regulations.gov. The EPA may publish any comment received to our public 
docket. Do not submit electronically any information you consider to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Multimedia submissions (audio, 
video, etc.) must be accompanied by a written comment. The written 
comment is considered the official comment and should include 
discussion of all points you wish to make. The EPA will generally not 
consider comments or comment contents located outside of the primary 
submission (i.e., comments hosted on the Web, Cloud, or other file 
sharing system). For additional submission methods, the full EPA public 
comment policy, information about CBI or multimedia submissions, and 
general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: For general questions concerning this 
action, please contact Corey Mocka, U.S. Environmental Protection 
Agency, Office of Air Quality Planning and Standards, Air Quality 
Policy Division, 109 T.W. Alexander Drive, Mail Code C539-04, Research 
Triangle Park, NC 27711; telephone: (919) 541-5142; email address: 
mocka.corey@epa.gov. The following EPA contacts can answer questions 
regarding areas in a particular EPA Regional office:
U.S. EPA Regional Office Contacts
    Region 2--Marina Castro, telephone (212) 637-3713, email at 
castro.marina@epa.gov.
    Region 3--Megan Goold, telephone (215) 814-2027, email at 
goold.megan@epa.gov.
    Region 4--Twunjala Bradley, telephone (404) 562-9352, email at 
bradley.twunjala@epa.gov.
    Region 5--Alisa Liu, telephone (312) 353-3193, email at 
liu.alisa@epa.gov.
    Region 6--Robert Imhoff, telephone (214) 665-7262, email at 
imhoff.robert@epa.gov.
    Region 7--William Stone, telephone (913) 551-7714, email at 
stone.william@epa.gov.
    Region 8--Rebecca Matichuk, telephone (303) 312-6867, email at 
matichuk.rebecca@epa.gov.
    Region 9--Ashley R. Graham, telephone (415) 972-3877, email at 
graham.ashleyr@epa.gov.
    Region 10--John Chi, telephone (206) 553-1185, email at 
chi.john@epa.gov.

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              Regional offices                    Affected state(s)
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EPA Region 2--Air Programs Branch, 290       New York.
 Broadway, 25th Floor, New York, NY 10007.
EPA Region 3--Planning & Implementation      Maryland, Pennsylvania,
 Branch, 1650 Arch Street, Philadelphia, PA   Virginia, and West
 19103.                                       Virginia.
EPA Region 4--Air Planning & Implementation  Alabama, Georgia, Kentucky,
 Branch, Sam Nunn Atlanta Federal Center,     and North Carolina.
 61 Forsyth Street SW, 12th Floor, Atlanta,
 GA 30303.
EPA Region 5--Air Programs Branch, Air &     Illinois, Indiana, and
 Radiation Division (AR-18J), 77 West         Wisconsin.
 Jackson Blvd., Chicago, IL 60604.
EPA Region 6--State Planning &               Louisiana, Oklahoma, and
 Implementation Branch, 1201 Elm Street,      Texas.
 Dallas, TX 75270.
EPA Region 7--Air Quality Planning Branch,   Missouri and Nebraska.
 11201 Renner Blvd., Lenexa, KS 66219.
EPA Region 8--Air Quality Planning Branch,   North Dakota and Wyoming.
 1595 Wynkoop Street, Denver, CO 80202.
EPA Region 9--Air Planning Branch, 75        Hawaii.
 Hawthorne Street, San Francisco, CA 94105.
EPA Region 10--Air Planning & State/Tribal   Washington.
 Coordinations Branch, 1200 Sixth Avenue,
 Mail Code OAQ-107, Seattle, WA 98101.
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[[Page 51695]]

    Most EPA offices are closed to reduce the risk of transmitting 
COVID-19, but staff remain available via telephone and email. The EPA 
encourages the public to review designation recommendations from 
states, our recent letters notifying the affected states of our 
intended designations, and area-specific technical support information 
online at https://www.epa.gov/sulfur-dioxide-designations and also in 
the public docket for these SO2 designations at https://www.regulations.gov under Docket ID No. EPA-HQ-OAR-2020-0037.

SUPPLEMENTARY INFORMATION: 

Table of Contents

    The following is an outline of the Preamble.

I. What is the purpose of this action?
II. Instructions for Submitting Public Comments and internet website 
for Rulemaking Information
III. What is the 2010 SO2 NAAQS and what are the health 
concerns that it addresses?
IV. What are the CAA requirements for air quality designations and 
what action has the EPA taken to meet these requirements?
V. What guidance has the EPA previously issued and how does the EPA 
now intend to apply the statutory requirements to determine area 
designations and boundaries?
VI. What air quality information has the EPA used for these intended 
designations?
VII. How do the Round 4 designations affect Indian country?
VIII. Where can I find information forming the basis for these 
intended designations and exchanges between the EPA and states 
related to these intended designations?

I. What is the purpose of this action?

    The purpose of this notice of availability is to solicit input from 
interested parties on the EPA's recent responses to the state 
designation recommendations for the 2010 SO2 NAAQS. These 
responses, and their supporting technical analyses, can be found at 
https://www.epa.gov/sulfur-dioxide-designations and also in the public 
docket for these SO2 designations at https://www.regulations.gov under Docket ID No. EPA-HQ-OAR-2020-0037.
    On June 2, 2010, the EPA Administrator signed a final rule that 
revised the primary SO2 NAAQS (75 FR 35520; June 22, 2010) 
after review of the existing primary SO2 standards 
promulgated on April 30, 1971 (36 FR 8187). The EPA established the 
revised primary SO2 NAAQS at a level of 75 parts per billion 
(ppb) which is attained when the 3-year average of annual 99th 
percentile of daily maximum 1-hour average concentrations of 
SO2 does not exceed 75 ppb.
    The process for designating areas following promulgation of a new 
or revised NAAQS is contained in the Clean Air Act (CAA or Act) section 
107(d) (42 U.S.C. 7407(d)). After promulgation of a new or revised 
NAAQS, each governor or tribal leader has an opportunity to recommend 
air quality designations, including the appropriate boundaries for 
nonattainment areas, to the EPA. The EPA considers these 
recommendations as part of its duty to promulgate the formal area 
designations and boundaries for the new or revised NAAQS. By no later 
than 120 days prior to promulgating designations, the EPA is required 
to notify states, territories, and tribes, as appropriate, of any 
intended modifications to an area designation or boundary 
recommendation that the EPA deems necessary.
    After invoking a 1-year extension of the deadlines to designate 
areas, as provided for in section 107 of the Act, the EPA completed an 
initial round of SO2 designations for certain areas of the 
country on July 25, 2013 (referred to as ``Round 1'').\2\ Following the 
initial designations, three lawsuits were filed against the EPA in 
different U.S. District Courts, alleging the agency had failed to 
perform a nondiscretionary duty under the CAA by not designating all 
portions of the country by the June 2, 2013, deadline. In one of those 
cases, the U.S. District Court for the Northern District of California 
on March 2, 2015, entered an enforceable order for the EPA to complete 
the area designations by three specific deadlines according to the 
court-ordered schedule.\3\
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    \2\ A total of 29 areas throughout the U.S. were designated in 
this action published on August 5, 2013 (78 FR 47191). The EPA 
designated all 29 areas nonattainment based on violating monitored 
SO2 concentrations from Federal Reference Method and 
Federal Equivalent Method monitors that are sited and operated in 
accordance with 40 CFR parts 50 and 58, and did not at that time 
designate any other areas.
    \3\ Sierra Club v. McCarthy, No. 3-13-cv-3953 (SI) (N.D. Cal. 
Mar. 2, 2015).
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    To meet the first court-ordered deadline, additional areas were 
designated on June 30, 2016, and November 29, 2016 (collectively 
referred to as ``Round 2'').\4\ To meet the second deadline of the 
court-ordered schedule, the EPA completed SO2 designations 
for most remaining areas of the country on December 21, 2017, and March 
28, 2018 (collectively referred to as ``Round 3'').\5\ Finally, the EPA 
is under a December 31, 2020, court-ordered deadline, the final of the 
three deadlines established by the court, to designate all remaining 
undesignated areas (collectively referred to as ``Round 4'' or the 
``final round''). The remaining undesignated areas are: (1) Those areas 
which, under the court order, did not meet the criteria that required 
designation in Round 2 and also were not required to be designated in 
Round 3 due to installation and operation of a new SO2 
monitoring network by January 2017 in the area meeting EPA's 
specifications referenced in EPA's SO2 Data Requirements 
Rule (DRR),\6\ and (2) those areas which EPA has not otherwise 
previously designated for the 2010 SO2 NAAQS. After these 
Round 4 designations are completed, there will be no remaining 
undesignated areas for the 2010 SO2 NAAQS.
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    \4\ A total of 65 areas throughout the U.S. were designated in 
these actions published on July 12, 2016 (81 FR 45039), and December 
13, 2016 (81 FR 89870). Of these 65 areas, seven were designated 
nonattainment.
    \5\ Most remaining areas of the U.S. were designated in actions 
published on January 9, 2018 (83 FR 1098) and April 5, 2018 (83 FR 
14597). Of these areas, six were designated nonattainment.
    \6\ See 80 FR 51052 (August 21, 2015), codified at 40 CFR part 
51 subpart BB.
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    On or about August 13, 2020, consistent with section 
107(d)(1)(b)(ii) of the CAA, the EPA notified affected states either of 
our assessment of their recommended designations for Round 4 or of our 
intended designations for areas without recommendations. While we are 
in agreement with the recommendations for many areas, some may warrant 
further discussion. The EPA is available to assist and hopes to resolve 
any differences regarding the proper designation for these areas within 
the 120-day period provided by the CAA.
    For any areas that we designate nonattainment in our final action, 
the CAA directs states to develop and submit to the EPA State 
Implementation Plans within 18 months of the effective date of the 
final designations, that meet the requirements of CAA sections 172(c) 
and 191-192 and provide for attainment of the NAAQS as expeditiously as 
practicable, but not later than 5 years from the effective date of the 
final designations.

II. Instructions for Submitting Public Comments and Internet Website 
for Rulemaking Information

A. Invitation To Comment

    The purpose of this document is to solicit input from interested 
parties, other than the states to which we have sent notification 
letters, on the EPA's recent responses to the designation 
recommendations for the 2010 SO2 NAAQS. These responses, and 
their

[[Page 51696]]

supporting technical analyses, can be found at https://www.epa.gov/sulfur-dioxide-designations and also in the public docket for these 
intended SO2 designations at https://www.regulations.gov 
under Docket ID No. EPA-HQ-OAR-2020-0037.
    CAA section 107(d) provides a process for air quality designations 
that involves recommendations by states, territories, and tribes to the 
EPA and responses from the EPA to those parties, prior to the EPA 
promulgating final area designations and boundaries. The EPA is not 
required under CAA section 107(d) to seek public comment during the 
designation process, but we are electing to do so for these areas with 
respect to the 2010 SO2 NAAQS in order to gather additional 
information for the EPA to consider before making final designations 
for the specific areas addressed in the EPA's recent letters to states, 
territories, and tribes. The EPA invites public input on our responses 
to states regarding our intended designations for these areas during 
the 30-day comment period provided in this document. In order to 
receive full consideration, input from the public must be submitted to 
the docket by September 21, 2020. At this time, the EPA is not asking 
for public comments on areas beyond those areas that are the subject of 
this proposed action. This document and opportunity for public comment 
does not affect any rights or obligations of any state, territory, or 
tribe, or of the EPA, which might otherwise exist pursuant to the CAA 
section 107(d).
    Please refer to the FOR FURTHER INFORMATION CONTACT section of this 
document for specific instructions on submitting comments and locating 
relevant public documents.
    For some cases, the EPA has indicated to a state that further 
discussion is needed--e.g., where a state's recommended nonattainment 
area boundary differs from the EPA's intended nonattainment area 
boundary, or areas where the state recommended a designation of 
attainment/unclassifiable (or unclassifiable) and available air quality 
monitoring or modeling data show that the area may be violating the 
2010 SO2 NAAQS or contain sources that may be contributing 
to air quality in a nearby area that may be violating the 2010 primary 
SO2 NAAQS. In establishing nonattainment area boundaries for 
a particular area, the EPA is required to include within the boundaries 
both the area that does not meet the standard and any nearby area 
contributing to the area that does not meet the standard. We are 
particularly interested in receiving comments, supported by relevant 
information, if you believe that a specific geographic area for which 
further discussion is needed concerning a state's recommended 
designation of attainment/unclassifiable or unclassifiable (and for 
which available air quality data would require a modification of the 
recommended designation) should not be categorized by the CAA section 
107(d) criteria as nonattainment, or if you believe that a specific 
nearby area for which the EPA does agree with a state's recommended 
designation of attainment/unclassifiable or unclassifiable should in 
fact be categorized as contributing to nonattainment using the CAA 
section 107(d) criteria. Please be as specific as possible in 
supporting your views.
     Describe any assumptions and provide any technical 
information and/or data that you used.
     Provide specific examples to illustrate your concerns and 
suggest alternatives.
     Explain your views as clearly as possible.
     Provide your input by the comment period deadline 
identified.
    The EPA intends to complete designations for the areas subject to 
this round no later than December 31, 2020. Additional information on 
the EPA's intended approach for addressing designations for all areas 
can be found on the EPA's SO2 implementation website at 
https://www.epa.gov/so2-pollution/applying-or-implementing-sulfur-dioxide-standards.

B. What should I consider as I prepare my comments for the EPA?

    1. Submitting CBI. Do not submit confidential business information 
(CBI) to the EPA through https://www.regulations.gov or email. Clearly 
mark the part or all of the information that you claim to be CBI. For 
CBI in a USB flash drive or CD ROM that you mail to the EPA, mark the 
outside of the USB flash drive or CD ROM as CBI and then identify 
electronically within the USB flash drive or CD ROM the specific 
information that is claimed as CBI. In addition to one complete version 
of the comment that includes information claimed as CBI, a copy of the 
comment that does not contain the information claimed as CBI must be 
submitted for inclusion in the public docket. Information so marked 
will not be disclosed except in accordance with procedures set forth in 
40 Code of Federal Regulations (CFR) part 2.
    Send information identified as CBI only to the following address: 
Tiffany Purifoy, OAQPS Document Control Officer, U.S. EPA, Office of 
Air Quality Planning and Standards, 109 T.W. Alexander Drive, Mail Code 
C404-02, Research Triangle Park, NC 27711, Attention Docket ID No. EPA-
HQ-OAR-2020-0037. There will be a delay in confirming receipt of CBI 
packages, because the EPA-RTP office is closed to reduce the risk of 
transmitting COVID-19. Due to the office closure, EPA is also 
requesting that parties notify the OAQPS Document Control Officer via 
telephone, (919) 541-0878, or email at purifoy.tiffany@epa.gov when 
mailing information identified as CBI.
    2. Tips for Preparing Your Comments. When submitting comments, 
remember to:
     Identify the rulemaking by docket number and other 
identifying information (subject heading, Federal Register date and 
page number).
     Follow directions.
     Explain why you agree or disagree; suggest alternatives 
and substitute language for your requested changes.

C. Where can I find additional information for this rulemaking?

    The EPA has also established a website for this rulemaking at 
https://www.epa.gov/sulfur-dioxide-designations. The website includes 
the state designation and boundary recommendations, the EPA's intended 
area designations, information supporting the EPA's preliminary 
designation decisions, as well as the rulemaking actions and other 
related information that the public may find useful.
III. What is the 2010 SO2 NAAQS and what are the health 
concerns that it addresses?
    The Administrator signed a final rule revising the primary 
SO2 NAAQS on June 2, 2010. The rule was published in the 
Federal Register on June 22, 2010 (75 FR 35520) and became effective on 
August 23, 2010. Specifically, the EPA established a new 1-hour 
SO2 standard at a level of 75 ppb, which is met at an 
ambient air quality monitoring site when the 3-year average of the 
annual 99th percentile of daily maximum 1-hour average concentrations 
of SO2 is less than or equal to 75 ppb, as determined in 
accordance with appendix T of 40 CFR part 50. 40 CFR 50.17(a) and (b). 
Current scientific evidence links short-term exposures to 
SO2, ranging from 5 minutes to 24 hours, with an array of 
adverse respiratory effects including bronchoconstriction and increased 
asthma symptoms. Studies also show a connection between short-term 
exposure and increased visits to emergency departments and hospital 
admissions for respiratory illnesses,

[[Page 51697]]

particularly in at-risk populations including children, the elderly, 
and asthmatics.\7\
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    \7\ See 75 FR 35520 at 35525, June 22, 2010.
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IV. What are the CAA requirements for air quality designations and what 
action has the EPA taken to meet these requirements?

    After the EPA promulgates a new or revised NAAQS, the EPA is 
required to designate all areas of the country as either 
``nonattainment,'' ``attainment,'' or ``unclassifiable,'' for that 
NAAQS pursuant to section 107(d)(1)-(2) of the CAA. As part of these 
Round 4 designations, the EPA is implementing its interpretation of 
statutory terms under CAA section 107(d) nationwide and is basing these 
designations on EPA's nationwide analytical approach and technical 
analysis, including evaluation of monitoring data and air quality 
modeling, applied to the available evidence for each area.
    Regarding statutory definitions and the EPA's interpretations of 
such, section 107(d)(1)(A)(i) of the CAA defines a nonattainment area 
as an area that does not meet the NAAQS or that contributes to a nearby 
area that does not meet the NAAQS. An attainment area is defined by 
section 107(d)(1)(A)(ii) of the CAA as any area (other than an area 
that meets the definition of a nonattainment area) that meets the 
NAAQS. Unclassifiable areas are defined by section 107(d)(1)(A)(iii) of 
the CAA as those that cannot be classified on the basis of available 
information as meeting or not meeting the NAAQS.
    In this action, the EPA defines a nonattainment area as an area 
that, based on available information including (but not limited to) 
monitoring data and/or appropriate modeling analyses, the EPA has 
determined either: (1) Does not meet the 2010 SO2 NAAQS, or 
(2) contributes to ambient air quality in a nearby area that does not 
meet the NAAQS. An attainment/unclassifiable area is defined as an area 
that, based on available information including (but not limited to) 
appropriate monitoring data and/or modeling analyses, the EPA has 
determined meets the NAAQS and does not likely contribute to ambient 
air quality in a nearby area that does not meet the NAAQS. An 
unclassifiable area is defined as an area for which the available 
information does not allow the EPA to determine whether the area meets 
the definition of a nonattainment area or the definition of an 
attainment/unclassifiable area.
    This nationwide analytical approach also includes but is not 
limited to: (1) The EPA's interpretations of other terms (e.g., 
attainment/unclassifiable, nonattainment, unclassifiable, violating 
monitor, etc.) in the context of Round 4 of the 2010 SO2 
NAAQS; (2) the appropriate basis for characterizing the air quality of 
an area; (3) the five-factor analysis to determine the boundaries for 
each air quality area under the NAAQS (see Section V of this document); 
and (4) the methodology for appropriately characterizing SO2 
air quality through monitoring or modeling.
    The EPA notes that CAA section 107(d) provides the agency with 
discretion to determine how best to interpret the terms in the 
definition of a nonattainment area (e.g., ``contributes to'' and 
``nearby'') for a new or revised NAAQS, given considerations such as 
the nature of a specific pollutant, the types of sources that may 
contribute to violations, the form of the standards for the pollutant, 
and other relevant information. In particular, the EPA's position is 
that the statute does not require the agency to establish bright line 
tests or thresholds for what constitutes ``contribution'' or ``nearby'' 
for purposes of designations.\8\
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    \8\ This view was confirmed in Catawba County v. EPA, 571 F.3d 
20 (D.C. Cir. 2009).
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    Similarly, the EPA's position is that the statute permits the EPA 
to evaluate the appropriate application of the term ``area'' to include 
geographic areas based upon full or partial county boundaries, as may 
be appropriate for a particular NAAQS. For example, CAA section 
107(d)(1)(B)(ii) explicitly provides that the EPA can make 
modifications to designation recommendations for an area ``or portions 
thereof,'' and under CAA section 107(d)(1)(B)(iv) a designation remains 
in effect for an area ``or portion thereof'' until the EPA redesignates 
it.
    By no later than 1 year after the promulgation of a new or revised 
NAAQS, CAA section 107(d)(1)(A) provides that each state governor is 
required to recommend air quality designations, including the 
appropriate boundaries for areas, to the EPA.\9\ The EPA reviews those 
recommendations and is authorized to make any modifications the 
Administrator deems necessary. The statute does not define the term 
``necessary,'' but the EPA interprets this to authorize the 
Administrator to modify designations that did not meet the statutory 
requirements or were otherwise inconsistent with the facts or analysis 
deemed appropriate by the Administrator. If the EPA is considering 
modifications to a recommendation, we are required by CAA section 
107(d)(1)(B)(ii) to notify the state of any such intended modifications 
not less than 120 days prior to our promulgation of the final 
designation. These notifications are commonly known as the ``120-day 
letters.'' During this period, if the state or territory does not agree 
with the EPA's modification, it has an opportunity to respond to the 
EPA and to demonstrate why it believes the modification proposed by the 
EPA is inappropriate. If a state or territory fails to provide any 
recommendation for an area, in whole or in part, the EPA still must 
promulgate a designation that the Administrator deems appropriate, 
pursuant to CAA section 107(d)(1)(B)(ii). While CAA section 107(d) 
specifically addresses the designations process between the EPA and 
states and territories, the EPA intends to follow the same process to 
the extent practicable for tribes that submitted designation 
recommendations. The EPA is required by CAA section 107(d)(2)(A) to 
publish a notice in the Federal Register promulgating its final 
designations, and the EPA codifies its designations in the Code of 
Federal Regulations at 40 CFR part 81, subpart C.
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    \9\ Tribes are invited to submit recommendations following 
promulgation of a new or revised NAAQS but are not required to do 
so.
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V. What guidance has the EPA previously issued and how does the EPA now 
intend to apply the statutory requirements to determine area 
designations and boundaries?

    In the notice of proposed rulemaking for the revised SO2 
NAAQS (74 FR 64810; December 8, 2009), the EPA issued proposed guidance 
on our approach to implementing the standard, including our approach to 
initial area designations. The EPA solicited comment on that guidance 
and, in the final rule (75 FR 35520; June 22, 2010), provided further 
guidance concerning implementation of the standard and how to identify 
nonattainment areas and boundaries for the SO2 NAAQS. 
Subsequently, on March 24, 2011, the EPA provided additional 
designations guidance to assist states with making their 
recommendations for area designations and boundaries.\10\ The EPA also 
issued two additional designations guidance documents on March 20, 
2015,

[[Page 51698]]

and July 22, 2016, specific to Round 2 and Round 3 processes and 
schedules, respectively.\11\
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    \10\ See ``Area Designations for the 2010 Revised Primary Sulfur 
Dioxide National Ambient Air Quality Standards,'' memorandum to 
Regional Air Division Directors, Regions I-X, from Stephen D. Page, 
dated March 24, 2011, available at https://www3.epa.gov/ttn/naaqs/aqmguide/collection/cp2/20110324_page_so2_designations_guidance.pdf.
    \11\ See ``Updated Guidance for Area Designations for the 2010 
Primary Sulfur Dioxide National Ambient Air Quality Standard,'' 
memorandum to Regional Air Division Directors, Regions 1-10, from 
Stephen D. Page, dated March 20, 2015, available at https://www.epa.gov/sites/production/files/2016-04/documents/20150320so2designations.pdf, and ``Area Designations for the 2010 
Primary Sulfur Dioxide National Ambient Air Quality Standard--Round 
3,'' memorandum to Regional Air Division Directors, Regions 1-10, 
dated July 22, 2016, available at https://www.epa.gov/sites/production/files/2016-07/documents/areadesign.pdf.
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    An updated designations guidance document was issued by the EPA on 
September 5, 2019, to better reflect the Round 4 2010 SO2 
NAAQS designations process and to supplement, where necessary, prior 
designations guidance documents.\12\ This memorandum identifies factors 
that the EPA intends to evaluate in determining whether areas are in 
violation of the 2010 SO2 NAAQS. The document also contains 
the factors that the EPA intends to evaluate in determining the 
boundaries for all remaining undesignated areas in the country. These 
factors include: (1) Air quality characterization via ambient 
monitoring and/or dispersion modeling results; (2) emissions-related 
data; (3) meteorology; (4) geography and topography; and (5) 
jurisdictional boundaries.\13\
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    \12\ See ``Area Designations for the 2010 Primary Sulfur Dioxide 
National Ambient Air Quality Standard--Round 4,'' memorandum to 
Regional Air Division Directors, Regions 1-10, from Peter 
Tsirigotis, dated September 5, 2019, available at https://www.epa.gov/sites/production/files/2019-09/documents/round_4_so2_designations_memo_09-05-2019_final.pdf.
    \13\ The EPA supplemented this guidance with documents first 
made available to states and other interested parties in 2013 and 
updated in 2016. See SO2 NAAQS Designations Source-
Oriented Monitoring Technical Assistance Document (February 2016), 
available at https://www.epa.gov/sites/production/files/2016-06/documents/so2monitoringtad.pdf, and SO2 NAAQS 
Designations Modeling Technical Assistance Document (August 2016), 
available at https://www.epa.gov/sites/production/files/2016-06/documents/so2modelingtad.pdf.
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VI. What air quality information has the EPA used for these intended 
designations?

    These intended designations are based on the EPA's application of 
the nationwide analytical approach to, and preliminary technical 
assessment of, the weight of evidence for each area, including but not 
limited to available air quality monitoring data and air quality 
modeling results. With respect to air quality monitoring data, the EPA 
has considered data from at least the most recent 3 full calendar 
years, i.e., 2017-2019. The 1-hour primary SO2 standard is 
violated at an ambient air quality monitoring site when the 3-year 
average of the annual 99th percentile of the daily maximum 1-hour 
average concentrations of SO2 exceeds 75 ppb, as determined 
in accordance with Appendix T of 40 CFR part 50.
    In the EPA's September 2019 memorandum, we noted that Round 4 area 
designations will be based primarily on ambient monitoring data, 
including data from existing and new EPA-approved monitors that have 
collected data at least from January 2017 forward, pursuant to the DRR. 
In addition, EPA may evaluate air dispersion modeling submitted by 
state air agencies for two specific circumstances. First, states may 
submit air dispersion modeling of actual or allowable emissions to 
support the geographic extent of a nonattainment boundary. Second, 
states may submit air dispersion modeling of allowable emissions to 
demonstrate that new permanent and federally enforceable SO2 
emissions limits that subject sources are meeting provide for 
attainment of the NAAQS and represent a more accurate characterization 
of current air quality at the time of designation than does monitoring 
data reflecting past air quality that does not account for compliance 
with new limits and associated enforceable emissions reductions.

VII. How do the Round 4 designations affect Indian country?

    There are no violating monitors for areas of Indian county, so no 
areas of Indian country are being designated as nonattainment as part 
of this round. Any other parts of Indian country being designated as 
attainment/unclassifiable or unclassifiable are being designated along 
with the surrounding state area.

VIII. Where can I find information forming the basis for these intended 
designations and exchanges between the EPA and states related to these 
intended designations?

    Information providing the basis for this intended action are 
provided in a technical support document (TSD) \14\ included in the 
docket. The TSD, technical assistance documents, applicable EPA 
guidance memoranda, and copies of correspondence regarding this process 
between the EPA and the states, territories, tribes, and other parties, 
are available for review at the public docket for these SO2 
designations at https://www.regulations.gov under Docket ID No. EPA-HQ-
OAR-2020-0037, at the EPA Docket Center listed in the FOR FURTHER 
INFORMATION CONTACT section of this document, and on the Agency's 
SO2 Designations website at https://www.epa.gov/sulfur-dioxide-designations. Air dispersion modeling input and output files 
are too large to post in the docket or on the website and must be 
requested from the EPA Docket Office or the Regional office contacts 
listed in the FOR FURTHER INFORMATION CONTACT section of this document.
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    \14\ The single TSD for this action consists of a few sections 
with information that applies to all affected areas or to certain 
groups of areas with some common features, and many sections that 
are specific to individual states. For convenience, the term ``TSD'' 
is also used generically to refer to these state-specific sections. 
For informational purposes, these individual state-specific TSDs are 
available for separate downloading from the indicated EPA website.

    Dated: August 13, 2020.
Panagiotis Tsirigotis,
Director, Office of Air Quality Planning & Standards.
[FR Doc. 2020-18129 Filed 8-20-20; 8:45 am]
BILLING CODE 6560-50-P