```

[Federal Register Volume 78, Number 144 (Friday, July 26, 2013)]
[Proposed Rules]
[Pages 45135-45152]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-18026]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R05-OAR-2011-0596; FRL-9837-9]

Approval and Promulgation of Air Quality Implementation Plans; 
Ohio; Redesignation of the Dayton-Springfield Area to Attainment of the 
1997 Annual Standard for Fine Particulate Matter

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA is proposing to approve the State of Ohio's request to 
redesignate the Dayton-Springfield nonattainment area (Dayton) to 
attainment for the 1997 annual National Ambient Air Quality Standards 
(NAAQS or standard) for fine particulate matter (PM2.5). EPA 
is also proposing to approve the related elements including emissions 
inventories, maintenance plans, and the accompanying motor vehicle 
budgets. EPA is proposing to approve a comprehensive emissions 
inventory that meets the Clean Air Act (CAA) requirement. EPA is 
proposing that the inventories for nitrogen oxides (NOX), 
direct PM2.5, sulfur dioxide (SO2), ammonia, and 
volatile organic compounds (VOC) meet the CAA emissions inventory 
requirement. In the course of proposing to approve Ohio's request to 
redesignate the Dayton area, EPA addresses a number of additional 
issues, including the effects of two decisions of the United States 
Court of Appeals for the District of Columbia (D.C. Circuit or Court): 
(1) The Court's August 21, 2012, decision to vacate and remand to EPA 
the Cross-State Air Pollution Control Rule (CSAPR) and (2) the Court's 
January 4, 2013, decision to remand to EPA two final rules implementing 
the 1997 PM2.5 standard.

DATES: Comments must be received on or before August 26, 2013.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2011-0596, by one of the following methods:
    1. www.regulations.gov: Follow the on-line instructions for 
submitting comments.
    2. Email: blakley.pamela@epa.gov.
    3. Fax: (312) 692-2450.
    4. Mail: Pamela Blakley, Chief, Control Strategies Section, Air 
Programs Branch (AR-18J), U.S. Environmental Protection Agency, 77 West 
Jackson Boulevard, Chicago, Illinois 60604.
    5. Hand delivery: Pamela Blakley, Chief, Control Strategies 
Section, Air Programs Branch (AR-18J), U.S. Environmental Protection 
Agency, 77 West Jackson Boulevard, Chicago, Illinois 60604. Such 
deliveries are only accepted during the Regional Office normal hours of 
operation, and special arrangements should be made for deliveries of 
boxed information. The Regional Office official hours of business are 
Monday through Friday, 8:30 a.m. to 4:30 p.m., excluding Federal 
holidays.
    Instructions: Direct your comments to Docket ID No. EPA-R05-OAR-
2011-0596. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available online at 
www.regulations.gov, including any personal information provided, 
unless the comment includes information claimed to be Confidential 
Business Information (CBI) or other information whose disclosure is 
restricted by statute. Do not submit information that you consider to 
be CBI or otherwise protected through www.regulations.gov or email. The 
www.regulations.gov Web site is an ``anonymous access'' system, which 
means EPA will not know your identity or contact information unless you 
provide it in the body of your comment. If you send an email comment 
directly to EPA without going through www.regulations.gov, your email 
address will be automatically captured and included as part of the 
comment that is placed in the public docket and made available on the 
Internet. If you submit an electronic comment, EPA recommends that you 
include your name and other contact information in the body of your

[[Page 45136]]

comment and with any disk or CD-ROM you submit. If EPA cannot read your 
comment due to technical difficulties and cannot contact you for 
clarification, EPA may not be able to consider your comment. Electronic 
files should avoid the use of special characters, any form of 
encryption, and be free of any defects or viruses. For additional 
instructions on submitting comments, go to Section I of this document, 
``What Should I Consider as I Prepare My Comments for EPA?''
    Docket: All documents in the docket are listed in the 
www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available either electronically 
in www.regulations.gov or in hard copy at the Environmental Protection 
Agency, Region 5, Air and Radiation Division, 77 West Jackson 
Boulevard, Chicago, Illinois 60604. This facility is open from 8:30 
a.m. to 4:30 p.m., Monday through Friday, excluding Federal holidays. 
We recommend that you telephone Matt Rau, Environmental Engineer, at 
(312) 886-6524 before visiting the Region 5 office.

FOR FURTHER INFORMATION CONTACT: Matt Rau, Environmental Engineer, 
Control Strategies Section, Air Programs Branch (AR-18J), Environmental 
Protection Agency, Region 5, 77 West Jackson Boulevard, Chicago, 
Illinois 60604, (312) 886-6524, rau.matthew@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,'' 
``us,'' or ``our'' is used, we mean EPA. This supplementary information 
section is arranged as follows:

I. What should I consider as I prepare my comments for EPA?
II. What is the background for the proposal?
III. What are the criteria for redesignation to attainment?
IV. What is EPA's analysis of Ohio's request?
    A. Attainment Determination and Redesignation
    B. Comprehensive Emissions Inventories
    C. Motor Vehicle Emission Budgets (MVEBs)
V. Summary of Proposed Actions
VI. Statutory and Executive Order Reviews

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

    When submitting comments, remember to:
    1. Identify the rulemaking by docket number and other identifying 
information (subject heading, Federal Register date, and page number).
    2. Follow directions--EPA may ask you to respond to specific 
questions or organize comments by referencing a Code of Federal 
Regulations (CFR) part or section number.
    3. Explain why you agree or disagree; suggest alternatives and 
substitute language for your requested changes.
    4. Describe any assumptions and provide any technical information 
and/or data that you used.
    5. If you estimate potential costs or burdens, explain how you 
arrived at your estimate in sufficient detail to allow for it to be 
reproduced.
    6. Provide specific examples to illustrate your concerns, and 
suggest alternatives.
    7. Explain your views as clearly as possible, avoiding the use of 
profanity or personal threats.
    8. Make sure to submit your comments by the comment period deadline 
identified.

II. What is the background for the proposal?

    On June 1, 2011, Ohio submitted a request for EPA to redesignate 
the Dayton-Springfield, Ohio nonattainment area to attainment of the 
1997 annual PM2.5 NAAQS. Ohio also requested EPA approval of 
the state implementation plan (SIP) revision containing an emissions 
inventory and a maintenance plan for the area.
    In a supplemental submission to EPA on April 30, 2013, Ohio 
submitted ammonia and VOC emissions inventories to supplement the 
emissions inventories for PM2.5, NOX, and 
SO2 that were submitted on June 1, 2011.
    Air quality standards for PM2.5 were promulgated on July 
18, 1997, at 62 FR 38652. EPA promulgated an annual standard at a level 
of 15 micrograms per cubic meter ([mu]g/m\3\), based on a three-year 
average of annual mean PM2.5 concentrations. In the same 
rulemaking, EPA set a 24-hour standard of 65 [mu]g/m\3\, based on a 
three-year average of the 98th percentile of 24-hour concentrations.
    On January 5, 2005, at 70 FR 944, EPA designated the Dayton area as 
nonattainment for the 1997 PM2.5 air quality standards. EPA 
defined the Dayton-Springfield nonattainment area to include Clark, 
Greene, and Montgomery Counties in Ohio.
    On October 17, 2006, at 71 FR 61144, EPA retained the annual 
average standard at 15 [mu]g/m\3\, but revised the 24-hour standard to 
35 [mu]g/m\3\, based again on the three-year average of the 98th 
percentile of 24-hour concentrations.
    In response to legal challenges of the annual standard promulgated 
in 2006, the DC Circuit remanded the standard to EPA for further 
consideration. See American Farm Bureau Federation and National Pork 
Producers Council, et al. v. EPA, 559 F.3d 512 (DC Cir. 2009). On 
December 14, 2012, EPA finalized a rule revising the PM2.5 
annual standard to 12 [mu]g/m\3\ based on current scientific evidence 
regarding the protection of public health. EPA is not addressing the 
2012 annual PM2.5 standard in this proposal.
    On September 14, 2011, at 76 FR 56641, EPA issued a final 
determination that the Dayton area attained the 1997 annual 
PM2.5 standard by the applicable attainment date of April 5, 
2010, based on certified ambient monitoring data for the 2007-2009 
monitoring period.
    Fine particle pollution can be emitted directly or formed 
secondarily through chemical reactions in the atmosphere. Sulfates are 
a type of secondary particle formed from SO2 emissions from 
power plants and industrial facilities. Nitrates, another common type 
of secondary particle, are formed from emissions of NOX from 
power plants, automobiles, and other combustion sources.
    Given the significance of sulfates and nitrates in the Dayton area, 
the area's air quality is strongly affected by regulations of 
SO2 and NOX emissions from power plants. EPA 
proposed the Clean Air Interstate Rule (CAIR) on January 30, 2004, at 
69 FR 4566, promulgated CAIR on May 12, 2005, at 70 FR 25162, and 
promulgated associated Federal implementation plans (FIPs) on April 28, 
2006, at 71 FR 25328, in order to reduce SO2 and 
NOX emissions and improve air quality in many areas in the 
Eastern and Midwestern United States. However, on July 11, 2008, the 
D.C. Circuit issued a decision to vacate and remand both CAIR and the 
associated CAIR FIPs in their entirety (North Carolina v. EPA, 531 F.3d 
836 (D.C. Cir. 2008)). EPA petitioned for rehearing, and the Court 
issued an order remanding CAIR and the CAIR FIPs to EPA without vacatur 
(North Carolina v. EPA, 550 F.3d 1176 (D.C. Cir. 2008)). The Court, 
thereby, left CAIR in place in order to ``temporarily preserve the 
environmental values covered by CAIR'' until EPA replaces it with a 
rule consistent with the Court's opinion. Id. at 1178. The Court 
directed EPA to ``remedy CAIR's flaws'' consistent with its July 11, 
2008, opinion, but declined to impose a schedule on EPA for completing 
that action.
    EPA issued CSAPR on August 8, 2011, at 76 FR 48208. CSAPR addresses 
interstate transport of emissions with respect to the 1997 ozone and 
the 1997 and 2006 PM2.5 NAAQS, and thus replaces CAIR. CSAPR 
requires substantial reductions of SO2 and NOX

[[Page 45137]]

emissions from electric generating units (EGUs) across most of the 
Eastern and Midwestern United States. CSAPR established permanent and 
enforceable limits on EGU emissions across 28 states.
    In this proposed redesignation, EPA takes into account two recent 
decisions of the D.C. Circuit. In the first of the two Court decisions, 
the D.C. Circuit, on August 21, 2012, issued EME Homer City Generation, 
L.P. v. EPA, 696 F.3d 7 (D.C. Cir. 2012), which vacated and remanded 
CSAPR and ordered EPA to continue administering CAIR ``pending . . . 
development of a valid replacement.'' EME Homer City at 38. The D.C. 
Circuit denied all petitions for rehearing on January 24, 2013. In the 
second decision, on January 4, 2013, in Natural Resources Defense 
Council v. EPA, the D.C. Circuit remanded to EPA the ``Final Clean Air 
Fine Particle Implementation Rule'' (72 FR 20586, April 25, 2007) and 
the ``Implementation of the New Source Review (NSR) Program for 
Particulate Matter Less than 2.5 Micrometers (PM2.5)'' final 
rule (73 FR 28321, May 16, 2008). 706 F.3d 428 (D.C. Cir. 2013).

III. What are the criteria for redesignation to attainment?

    The requirements for redesignating an area from nonattainment to 
attainment are found in CAA section 107(d)(3)(E). There are five 
criteria for redesignating an area. First, the Administrator must 
determine that an area has attained the applicable NAAQS based on 
current air quality data. Second, the Administrator has fully approved 
the applicable SIP for the area under CAA section 110(k). The third 
criterion is for the Administrator to determine that the air quality 
improvement is the result of permanent and enforceable emission 
reductions. Emission reductions resulting from requirements approved 
into the SIP and from Federal air pollution control requirements are 
considered permanent and enforceable. Fourth, the Administrator has 
fully approved a maintenance plan meeting the CAA section 175A 
requirements. The fifth criterion is that the state has met all the 
redesignation requirements of CAA section 110 and part D.

IV. What is EPA's analysis of Ohio's request?

A. Attainment Determination and Redesignation

    EPA is proposing to determine that the Dayton area continues to 
attain the PM2.5 annual standard. EPA is also proposing to 
approve Ohio's maintenance plans for the area and to determine that the 
area has met all other applicable redesignation criteria under CAA 
section 107(d)(3)(E). The basis for EPA's proposed approval of the 
redesignation requests is as follows:
1. The Area Has Attained the 1997 Annual PM2.5 NAAQS
    EPA examined monitoring data to determine if the area currently 
meets the PM2.5 annual standard, as determined in accordance 
with 40 CFR 50.7 and part 50, appendix N, based on three complete 
consecutive calendar years of quality-assured air quality monitoring 
data. EPA is proposing to find that the Dayton area is continuing to 
meet the annual PM2.5 standard. The monitoring data for the 
Dayton area are found on Table 1.

                                Table 1--Dayton Area Annual PM2.5 Monitoring Data
                                                  [[mu]g/m\3\]
----------------------------------------------------------------------------------------------------------------
                             County                                  2008-2010       2009-2011       2010-2012
----------------------------------------------------------------------------------------------------------------
Clark...........................................................            12.7            12.6            11.9
Greene..........................................................            12.1            12.0            11.4
Montgomery......................................................            13.2            12.9            12.3
----------------------------------------------------------------------------------------------------------------

    EPA makes the determination of whether an area's air quality is 
meeting the PM2.5 NAAQS primarily based upon data gathered 
from the air quality monitoring sites that have been entered into EPA's 
Air Quality System (AQS) database. To show attainment of the annual 
standard for PM2.5, the most recent three consecutive years 
of data prior to the area's attainment date must show that 
PM2.5 concentrations over a three-year period are at or 
below the level of the standard, 15.0 [mu]g/m\3\.
    Ohio submitted its requests based on 2008 to 2010 monitoring data 
showing that the Dayton area continues to attain the PM2.5 
standard. Monitoring data for 2011 and 2012 became available from AQS 
since Ohio submitted its request. The 2010 to 2012 design values above 
reflect preliminary calculations of design value based on quality 
assured, certified air quality data. Thus, EPA also examined the 2009 
to 2011 and 2010 to 2012 averages for each monitoring site in the 
Dayton area. This current monitoring data as presented on Table 1 shows 
that the area continues to attain the annual standard.
    Greene County has a single PM2.5 monitor, site 39-057-
0005, located in Yellow Springs. This site has operated since October 
2003, but it had just a 45 percent data capture in the third quarter of 
2010. EPA's completeness criterion is 75 percent data capture for every 
quarter. Thus, the 2010 data are incomplete, as are all three-year 
periods that include 2010 data. Ohio explained in its submission that 
the Greene County monitor was down from August 12 to September 29, 
2010, due to repairs to the roof of the building hosting the monitoring 
site. EPA data shows that this monitor had at least 93 percent data 
capture in the other 11 quarters in the 2009 to 2011 period. The 2012 
monitoring data indicates all four quarters of data are complete and 
thus EPA finds the Greene County monitor to have 11 complete quarters 
of data for the 2010 to 2012 period.
    EPA examined air quality in Greene County in several ways. First, 
EPA examined data for the most recent complete three years of data at 
this site. The most recent three-year period with complete data is 2007 
to 2009, during which Greene County recorded a design value of 12.1 
[mu]g/m\3\, which is well below the standard. These data, in 
combination with the subsequent incomplete data suggesting continued 
attainment, provide adequate evidence that this location is attaining 
the standard.
    Second, Ohio performed an analysis of the missing data for the 
Greene County monitoring site. Ohio substituted data from the other 
monitors in the Dayton area for the 17 missing values from August and 
September 2010. There are two other monitors in the area, one each in 
Clark and Montgomery Counties. The state determined that the Clark 
County monitor data had a 0.9236 correlation with the Greene County 
data. The substitute values in the third quarter actually lower the 
2010 average from 13.2 to 12.2 [mu]g/m\3\.
    Third, EPA examined the monitoring data history for Greene County. 
The site

[[Page 45138]]

recorded an average of 17.24 [mu]g/m\3\ for the third quarter of 2010, 
which compares to the average of 14.43 [mu]g/m\3\ for Clark County and 
14.84 [mu]g/m\3\ for Montgomery County. The 2010 average for the sites 
are closer with Greene County having a 13.2 [mu]g/m\3\ annual average, 
Clark County was at 13.1 [mu]g/m\3\, and 14.0 [mu]g/m\3\ for Montgomery 
County.
    Looking back further, Greene County has recorded annual design 
values of 13.6 [mu]g/m\3\ in 2005 to 2007, 12.3 [mu]g/m\3\ in 2006 to 
2008, and 12.1 [mu]g/m\3\ in 2007 to 2009. The annual design values for 
Clark County are 14.8 [mu]g/m\3\ in 2005 to 2007, 13.5 [mu]g/m\3\ in 
2006 to 2008, and 13.3 [mu]g/m\3\ in 2007 to 2009. The Montgomery 
County annual design values are 15.5 [mu]g/m\3\ in 2005 to 2007, 14.2 
[mu]g/m\3\ in 2006 to 2008, and 13.8 [mu]g/m\3\ in 2007 to 2009. The 
design value history shows that the ambient air quality in Greene 
County has consistently had the lowest design value in the Dayton area, 
while Montgomery County recorded the area's highest design values. The 
2010 design value for Greene County was similar to the Clark County 
value, while remaining lower than the Montgomery County value. This can 
be attributed to uncharacteristically high 2010 third quarter average 
that had 17 missing values. Ohio analysis showed that adding typical 
values for the missing data would have lowered the 2010 average. The 
2008 to 2010, 2009 to 2011, and the preliminary 2010 to 2012 Greene 
County design values are well below the PM2.5 standard. The 
other two monitors recorded values moderately below the standard during 
2010's third quarter. Thus, it is likely that the 2008 to 2010, 2009 to 
2011, and 2010 to 2012 Greene County design values would not have been 
any higher had site 39-057-0005 recorded complete data for the third 
quarter of 2010.
    For all these reasons, EPA believes that the Dayton area continues 
to attain the annual PM2.5 standard based on current data.
2. The Area Has Met All Applicable Requirements Under Section 110 and 
Part D; and the Area Has a Fully Approved SIP Under Section 110(k)
    The requirements for a state to have a fully approved SIP meeting 
all relevant requirements are specified in CAA sections 
107(d)(3)(E)(ii) and 107(d)(3)(E)(v).
    EPA has determined that Ohio has met all currently applicable SIP 
requirements for purposes of redesignation for the Dayton area under 
CAA section 110, general SIP requirements. EPA has also determined that 
the Ohio SIP meets all SIP requirements currently applicable for 
purposes of redesignation in accordance with section 107(d)(3)(E)(v). 
In addition, with the exception of the emissions inventory under 
section 172(c)(3), we have approved all applicable requirements of the 
Ohio SIP for purposes of redesignation, in accordance with section 
107(d)(3)(E)(ii). As discussed below, in this action EPA is proposing 
to approve Ohio's 2005 and 2008 emissions inventories as meeting the 
section 172(c)(3) comprehensive emissions inventory requirement.
    In making these determinations, EPA ascertained what SIP 
requirements are applicable to the area for purposes of this 
redesignation and determined that the portions of the SIP meeting these 
requirements are fully approved under section 110(k) of the CAA. SIPs 
must be fully approved only with respect to currently applicable 
requirements of the CAA.
a. The Dayton Area Has Met All Applicable Requirements for Purposes of 
Redesignation Under Section 110 and Part D of the CAA
i. Section 110(a) General SIP Requirements
    Section 110(a) of title I of the CAA contains the general 
requirements for a SIP. Section 110(a)(2) provides that the 
implementation plan submitted by a state must have been adopted by the 
state after reasonable public notice and hearing, and, among other 
things, must: Include enforceable emission limitations and other 
control measures, means or techniques necessary to meet the 
requirements of the CAA; provide for establishment and operation of 
appropriate devices, methods, systems, and procedures necessary to 
monitor ambient air quality; provide for implementation of a source 
permit program to regulate the modification and construction of any 
stationary source within the areas covered by the plan; include 
provisions for the implementation of part C, Prevention of Significant 
Deterioration (PSD) and part D, NSR permit programs; include criteria 
for stationary source emission control measures, monitoring, and 
reporting; include provisions for air quality modeling; and provide for 
public and local agency participation in planning and emission control 
rule development.
    Section 110(a)(2)(D) of the CAA requires that SIPs contain measures 
to prevent sources in a state from significantly contributing to air 
quality problems in another state. EPA holds that the requirements 
linked with a particular nonattainment area's designation are the 
relevant measures to evaluate in reviewing a redesignation request. The 
transport SIP submittal requirements, where applicable, continue to 
apply to a state regardless of the designation of any one particular 
area in the state. Thus, we conclude that these requirements should not 
be construed to be applicable requirements for purposes of 
redesignation.
    EPA believes that section 110 elements not connected with 
nonattainment plan submissions and not linked to an area's 
nonattainment status are not applicable requirements for 
redesignations. EPA reviews the state's request to redesignate an area 
to attainment based on the CAA requirements.
    This approach is consistent with EPA's existing policy on 
applicability of conformity and oxygenated fuels requirements for 
redesignation purposes, as well as with section 184 ozone transport 
requirements. See Reading, Pennsylvania, proposed and final rulemakings 
(61 FR 53174-53176, October 10, 1996) and (62 FR 24826, May 7, 1997); 
Cleveland-Akron-Lorain, Ohio, final rulemaking (61 FR 20458, May 7, 
1996); and Tampa, Florida, final rulemaking (60 FR 62748, December 7, 
1995). See also the discussion on this issue in the Cincinnati, Ohio 1-
hour ozone redesignation (65 FR 37890, June 19, 2000), and in the 
Pittsburgh, Pennsylvania 1-hour ozone redesignation (66 FR 50399, 
October 19, 2001).
    We have reviewed the Ohio SIP and have concluded that it meets the 
general SIP requirements under section 110 of the CAA to the extent 
they are applicable for purposes of redesignation. EPA has previously 
approved provisions of Ohio's SIP addressing section 110 requirements, 
including provisions addressing particulate matter, at 40 CFR 52.1870. 
On December 5, 2007, and September 4, 2009, Ohio made submittals 
addressing ``infrastructure SIP'' elements required by section 
110(a)(2) of the CAA. EPA approved elements of Ohio's submittals on 
July 13, 2011, at 76 FR 41075. The requirements of section 110(a)(2), 
however, are statewide requirements that are not linked to the 
PM2.5 nonattainment status of the Dayton area. Therefore, 
EPA believes that these SIP elements are not applicable requirements 
for purposes of review of the Ohio PM2.5 redesignation 
requests.
ii. Part D Requirements
    EPA is proposing to determine that, upon approval of the base year 
emissions inventories discussed in

[[Page 45139]]

section IV.B., the Ohio SIP will meet the applicable SIP requirements 
for the Dayton area applicable for purposes of redesignation under part 
D of the CAA. Subpart 1 of part D, found in sections 172-176 of the 
CAA, sets forth the basic nonattainment requirements applicable to all 
nonattainment areas. Subpart 4 of part D, found in sections 185-190 of 
the CAA, provides more specific requirements for particulate matter 
nonattainment areas.
(1) Subpart 1
(a) Section 172 Requirements
    For purposes of evaluating these redesignation requests, the 
applicable section 172 SIP requirements for the Dayton area are 
contained in sections 172(c)(1)-(9). A thorough discussion of the 
requirements contained in section 172 can be found in the General 
Preamble for Implementation of Title I (57 FR 13498, April 16, 1992).
    Section 172(c)(1) requires the plans for all nonattainment areas to 
provide for the implementation of all Reasonably Available Control 
Measures (RACM) as expeditiously as practicable and to provide for 
attainment of the primary NAAQS. EPA interprets this requirement to 
impose a duty on all nonattainment areas to consider all available 
control measures and to adopt and implement such measures as are 
reasonably available for implementation in each area as components of 
the area's attainment demonstration. Since attainment has been reached, 
no additional measures are needed to provide for attainment, and 
section 172(c)(1) requirements are no longer considered to be 
applicable as long as the area continues to attain the standard until 
redesignation. See 40 CFR 51.1004(c). The Reasonable Further Progress 
(RFP) requirement under section 172(c)(2) is defined as progress that 
must be made toward attainment. This requirement is not relevant for 
purposes of this redesignation because the Dayton area is monitoring 
attainment of the 1997 annual PM2.5 NAAQS. The requirement 
to submit the section 172(c)(9) contingency measures is similarly not 
applicable for purposes of this redesignation.
    Section 172(c)(3) requires submission and approval of a 
comprehensive, accurate, and current inventory of actual emissions. 
Ohio submitted 2005 and 2008 emissions inventories along with their 
redesignation request and supplemented the inventories on April 30, 
2013. As discussed in section IV.B., EPA is proposing to approve the 
2005 and 2008 emission inventories as meeting the section 172(c)(3) 
emissions inventory requirement for the Dayton area.
    Section 172(c)(4) requires the identification and quantification of 
allowable emissions for major new and modified stationary sources in an 
area, and section 172(c)(5) requires source permits for the 
construction and operation of new and modified major stationary sources 
anywhere in the nonattainment area. EPA approved Ohio's current NSR 
program on January 10, 2003 (68 FR 1366). Nonetheless, since PSD 
requirements will apply after redesignation, the area does not need to 
have a fully-approved NSR program for purposes of redesignation, 
provided that the area demonstrates maintenance of the NAAQS without 
part D NSR. A detailed rationale for this view is described in a 
memorandum from Mary Nichols, Assistant Administrator for Air and 
Radiation, dated October 14, 1994, entitled, ``Part D New Source Review 
Requirements for Areas Requesting Redesignation to Attainment'' 
(Nichols memorandum). Ohio has demonstrated that the Dayton area will 
be able to maintain the standard without part D NSR in effect; 
therefore, the state does not need to have a fully approved part D NSR 
program prior to approval of the redesignation request. Ohio's PSD 
program will become effective in the Dayton area upon redesignation to 
attainment. See rulemakings for Detroit, Michigan (60 FR 12467-12468, 
March 7, 1995); Cleveland-Akron-Lorain, Ohio (61 FR 20458, 20469-20470, 
May 7, 1996); Louisville, Kentucky (66 FR 53665, October 23, 2001); and 
Grand Rapids, Michigan (61 FR 31834-31837, June 21, 1996).
    Section 172(c)(6) requires the SIP to contain control measures 
necessary to provide for attainment of the standard. As attainment has 
been reached, no additional measures are needed to provide for 
attainment.
    Section 172(c)(7) requires the SIP to meet the applicable 
provisions of section 110(a)(2). As noted, EPA finds that the Ohio SIP 
meets the section 110(a)(2) requirements applicable for purposes of 
redesignation.
(b) Section 176 Conformity Requirements
    Section 176(c) of the CAA requires states to establish criteria and 
procedures to ensure that Federally-supported or funded activities, 
including highway projects, conform to the air quality planning goals 
in the applicable SIPs. The requirement to determine conformity applies 
to transportation plans, programs, and projects developed, funded, or 
approved under title 23 of the U.S. Code and the Federal Transit Act 
(transportation conformity) as well as to all other Federally-supported 
or funded projects (general conformity).
    Section 176(c) of the CAA was amended by provisions contained in 
the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A 
Legacy for Users (SAFETEA-LU), which was signed into law on August 10, 
2005 (Pub. L. 109-59). Among the changes Congress made to this section 
of the CAA were streamlined requirements for state transportation 
conformity SIPs. State transportation conformity regulations must be 
consistent with Federal conformity regulations and address three 
specific requirements related to consultation, enforcement, and 
enforceability. EPA believes that it is reasonable to interpret the 
transportation conformity SIP requirements as not applying for purposes 
of evaluating the redesignation request under section 107(d) for two 
reasons.
    First, the requirement to submit SIP revisions to comply with the 
transportation conformity provisions of the CAA continues to apply to 
areas after redesignation to attainment since such areas would be 
subject to a section 175A maintenance plan. Second, EPA's Federal 
conformity rules require the performance of conformity analyses in the 
absence of Federally-approved state rules. Therefore, because areas are 
subject to the transportation conformity requirements regardless of 
whether they are redesignated to attainment and, because they must 
implement conformity under Federal rules if state rules are not yet 
approved, EPA believes it is reasonable to view these requirements as 
not applying for purposes of evaluating a redesignation request. See 
Wall v. EPA, 265 F.3d 426 (6th Cir. 2001), upholding this 
interpretation. See also 60 FR 62748, 62749-62750 (Dec. 7, 1995) 
(Tampa, Florida).
    EPA approved Ohio's general conformity SIP on March 11, 1996 (61 FR 
9646), and Ohio's transportation conformity SIP on May 30, 2000 (65 FR 
34395), and April 27, 2007 (72 FR 20945). Ohio is in the process of 
updating its approved transportation conformity SIP, and EPA will 
review its provisions when they are submitted. Ohio also submitted 
onroad motor vehicle emission budgets for transportation conformity 
purposes, which EPA reviews in section IV.C below.

[[Page 45140]]

(2) Effect of the January 4, 2013, D.C. Circuit Decision Regarding 
PM2.5 Implementation Under Subpart 4
(a) Background
    As discussed above, on January 4, 2013, in Natural Resources 
Defense Council v. EPA, the D.C. Circuit remanded to EPA the ``Final 
Clean Air Fine Particle Implementation Rule'' (72 FR 20586, April 25, 
2007) and the ``Implementation of the New Source Review (NSR) Program 
for Particulate Matter Less than 2.5 Micrometers (PM2.5)'' 
final rule (73 FR 28321, May 16, 2008) (collectively, ``1997 
PM2.5 Implementation Rule''). 706 F.3d 428 (D.C. Cir. 2013). 
The Court found that EPA erred in implementing the 1997 
PM2.5 NAAQS pursuant to the general implementation 
provisions of subpart 1 of part D of title I of the CAA, rather than 
the particulate-matter-specific provisions of subpart 4 of part D of 
title I.
2. Proposal on This Issue
    EPA is proposing to determine that the Court's January 4, 2013, 
decision does not prevent EPA from redesignating the Dayton area to 
attainment. Even in light of the Court's decision, redesignation for 
this area is appropriate under the CAA and EPA's longstanding 
interpretations of the CAA's provisions regarding redesignation.
i. Applicable Requirements for Purposes of Evaluating the Redesignation 
Request
    With respect to the 1997 PM2.5 Implementation Rule, the 
D.C. Circuit's January 4, 2013, ruling rejected EPA's reasons for 
implementing the PM2.5 NAAQS solely in accordance with the 
provisions of subpart 1, and remanded that matter to EPA, so that it 
could address implementation of the 1997 PM2.5 NAAQS under 
subpart 4 of part D of the CAA, in addition to subpart 1. For the 
purposes of evaluating Ohio's redesignation request for the area, to 
the extent that implementation under subpart 4 would impose additional 
requirements for areas designated nonattainment, EPA believes that 
those requirements are not ``applicable'' for the purposes of CAA 
section 107(d)(3)(E), and thus EPA is not required to consider subpart 
4 requirements for the Dayton redesignation. Under its longstanding 
interpretation of the CAA, EPA has interpreted section 107(d)(3)(E) to 
mean, as a threshold matter, that the part D provisions which are 
``applicable'' and which must be approved in order for EPA to 
redesignate an area include only those which came due prior to a 
State's submission of a complete redesignation request. See 
``Procedures for Processing Requests to Redesignate Areas to 
Attainment,'' Memorandum from John Calcagni, Director, Air Quality 
Management Division, September 4, 1992 (Calcagni memorandum). See also 
``State Implementation Plan (SIP) Requirements for Areas Submitting 
Requests for Redesignation to Attainment of the Ozone and Carbon 
Monoxide (CO) National Ambient Air Quality Standards (NAAQS) on or 
after November 15, 1992,'' Memorandum from Michael Shapiro, Acting 
Assistant Administrator, Air and Radiation, September 17, 1993 (Shapiro 
memorandum); Final Redesignation of Detroit-Ann Arbor, (60 FR 12459, 
12465-66, March 7, 1995); Final Redesignation of St. Louis, Missouri, 
(68 FR 25418, 25424-27, May 12, 2003); Sierra Club v. EPA, 375 F.3d 
537, 541 (7th Cir. 2004) (upholding EPA's redesignation rulemaking 
applying this interpretation and expressly rejecting Sierra Club's view 
that the meaning of ``applicable'' under the statute is ``whatever 
should have been in the plan at the time of attainment rather than 
whatever actually was in the plan and already implemented or due at the 
time of attainment'').\1\ In this case, at the time that Ohio submitted 
its redesignation request, requirements under subpart 4 were not due, 
and indeed, were not yet known to apply.
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    \1\ Applicable requirements of the CAA that come due subsequent 
to the area's submittal of a complete redesignation request remain 
applicable until a redesignation is approved, but are not required 
as a prerequisite to redesignation. Section 175A(c) of the CAA.
---------------------------------------------------------------------------

    EPA's view that, for purposes of evaluating the Dayton 
redesignation, the subpart 4 requirements were not due at the time the 
state submitted the redesignation request is in keeping with the EPA's 
interpretation of subpart 2 requirements for subpart 1 ozone areas 
redesignated subsequent to the D.C. Circuit's decision in South Coast 
Air Quality Mgmt. Dist. v. EPA, 472 F.3d 882 (D.C. Cir. 2006). In South 
Coast, the Court found that EPA was not permitted to implement the 1997 
8-hour ozone standard solely under subpart 1, and held that EPA was 
required under the statute to implement the standard under the ozone-
specific requirements of subpart 2 as well. Subsequent to the South 
Coast decision, in evaluating and acting upon redesignation requests 
for the 1997 8-hour ozone standard that were submitted to EPA for areas 
under subpart 1, EPA applied its longstanding interpretation of the CAA 
that ``applicable requirements'', for purposes of evaluating a 
redesignation, are those that had been due at the time the 
redesignation request was submitted. See, e.g., Proposed Redesignation 
of Manitowoc County and Door County Nonattainment Areas (75 FR 22047, 
22050, April 27, 2010). In those actions, EPA therefore did not 
consider subpart 2 requirements to be ``applicable'' for the purposes 
of evaluating whether the area should be redesignated under section 
107(d)(3)(E).
    EPA's interpretation derives from the provisions of CAA section 
107(d)(3). Section 107(d)(3)(E)(v) states that, for an area to be 
redesignated, a state must meet ``all requirements `applicable' to the 
area under section 110 and part D.'' Section 107(d)(3)(E)(ii) provides 
that the EPA must have fully approved the ``applicable'' SIP for the 
area seeking redesignation. These two sections read together support 
EPA's interpretation of ``applicable'' as only those requirements that 
came due prior to submission of a complete redesignation request. 
First, holding states to an ongoing obligation to adopt new CAA 
requirements that arose after the state submitted its redesignation 
request, in order to be redesignated, would make it problematic or 
impossible for EPA to act on redesignation requests in accordance with 
the 18-month deadline Congress set for EPA action in section 
107(d)(3)(D). If ``applicable requirements'' were interpreted to be a 
continuing flow of requirements with no reasonable limitation, states, 
after submitting a redesignation request, would be forced continuously 
to make additional SIP submissions that in turn would require EPA to 
undertake further notice-and-comment rulemaking actions to act on those 
submissions. This would create a regime of unceasing rulemaking that 
would delay action on the redesignation request beyond the 18-month 
timeframe provided by the CAA for this purpose.
    Second, a fundamental premise for redesignating a nonattainment 
area to attainment is that the area has attained the relevant NAAQS due 
to emission reductions from existing controls. Thus, an area for which 
a redesignation request has been submitted would have already attained 
the NAAQS as a result of satisfying statutory requirements that came 
due prior to the submission of the request. Absent a showing that 
unadopted and unimplemented requirements are necessary for future 
maintenance, it is reasonable to view the requirements applicable for 
purposes of evaluating the redesignation request as including only 
those SIP requirements that have already come due. These are the 
requirements that led to attainment of the NAAQS. To require,

[[Page 45141]]

for redesignation approval, that a state also satisfy additional SIP 
requirements coming due after the state submits its complete 
redesignation request, and while EPA is reviewing it, would compel the 
state to do more than is necessary to attain the NAAQS, without a 
showing that the additional requirements are necessary for maintenance.
    In the context of this redesignation, the timing and nature of the 
Court's January 4, 2013, decision in NRDC v. EPA compound the 
consequences of imposing requirements that come due after the 
redesignation request is submitted. The state submitted its 
redesignation request on June 1, 2011, but the Court did not issue its 
decision remanding EPA's 1997 PM2.5 implementation rule 
concerning the applicability of the provisions of subpart 4 until 
January 2013.
    To require the state's fully-completed and pending redesignation 
request to comply now with requirements of subpart 4 that the Court 
announced only in January, 2013, would be to give retroactive effect to 
such requirements when the state had no notice that it was required to 
meet them. The D.C. Circuit recognized the inequity of this type of 
retroactive impact in Sierra Club v. Whitman, 285 F.3d 63 (D.C. Cir. 
2002),\2\ where it upheld the District Court's ruling refusing to make 
retroactive EPA's determination that the St. Louis area did not meet 
its attainment deadline. In that case, petitioners urged the Court to 
make EPA's nonattainment determination effective as of the date that 
the statute required, rather than the later date on which EPA actually 
made the determination. The Court rejected this view, stating that 
applying it ``would likely impose large costs on states, which would 
face fines and suits for not implementing air pollution prevention 
plans . . . even though they were not on notice at the time.'' Id. at 
68. Similarly, it would be unreasonable to penalize Ohio by rejecting 
its redesignation request for an area that is already attaining the 
1997 PM2.5 standard and that met all applicable requirements 
known to be in effect at the time of the request. For EPA now to reject 
the redesignation request solely because the state did not expressly 
address subpart 4 requirements of which it had no notice, would inflict 
the same unfairness condemned by the Court in Sierra Club v. Whitman.
---------------------------------------------------------------------------

    \2\ Sierra Club v. Whitman was discussed and distinguished in a 
recent D.C. Circuit decision that addressed retroactivity in a quite 
different context, where, unlike the situation here, EPA sought to 
give its regulations retroactive effect. National Petrochemical and 
Refiners Ass'n v. EPA. 630 F.3d 145, 163 (D.C. Cir. 2010), rehearing 
denied 643 F.3d 958 (D.C. Cir. 2011), cert denied 132 S. Ct. 571 
(2011).
---------------------------------------------------------------------------

ii. Subpart 4 Requirements and Ohio's Redesignation Request
    Even if EPA were to take the view that the Court's January 4, 2013, 
decision requires that, in the context of pending redesignations, 
subpart 4 requirements were due and in effect at the time the State 
submitted its redesignation request, EPA proposes to determine that the 
Dayton area still qualifies for redesignation to attainment. As 
explained below, EPA believes that the redesignation request for the 
Dayton area, though not expressed in terms of subpart 4 requirements, 
substantively meets the requirements of that subpart for purposes of 
redesignating the area to attainment.
    With respect to evaluating the relevant substantive requirements of 
subpart 4 for purposes of redesignating the Dayton area, EPA notes that 
subpart 4 incorporates components of subpart 1 of part D, which 
contains general air quality planning requirements for areas designated 
as nonattainment. See Section 172(c). Subpart 4 itself contains 
specific planning and scheduling requirements for PM10 \3\ 
nonattainment areas, and under the Court's January 4, 2013, decision in 
NRDC v. EPA, these same statutory requirements also apply for 
PM2.5 nonattainment areas. EPA has longstanding general 
guidance that interprets the 1990 amendments to the CAA, making 
recommendations to states for meeting the statutory requirements for 
SIPs for nonattainment areas. See, ``State Implementation Plans; 
General Preamble for the Implementation of Title I of the Clear Air Act 
Amendments of 1990,'' 57 FR 13498 (April 16, 1992) (the ``General 
Preamble''). In the General Preamble, EPA discussed the relationship of 
subpart 1 and subpart 4 SIP requirements, and pointed out that subpart 
1 requirements were to an extent ``subsumed by, or integrally related 
to, the more specific PM-10 requirements.'' 57 FR 13538 (April 16, 
1992). The subpart 1 requirements include, among other things, 
provisions for attainment demonstrations, RACM, RFP, emissions 
inventories, and contingency measures.
---------------------------------------------------------------------------

    \3\ PM10 refers to particulates nominally 10 
micrometers in diameter or smaller.
---------------------------------------------------------------------------

    For the purposes of this redesignation, in order to identify any 
additional requirements which would apply under subpart 4, we are 
considering the Dayton area to be a ``moderate'' PM2.5 
nonattainment area. Under section 188 of the CAA, all areas designated 
nonattainment areas under subpart 4 would initially be classified by 
operation of law as ``moderate'' nonattainment areas, and would remain 
moderate nonattainment areas unless and until EPA reclassifies the area 
as a ``serious'' nonattainment area. Accordingly, EPA believes that it 
is appropriate to limit the evaluation of the potential impact of 
subpart 4 requirements to those that would be applicable to moderate 
nonattainment areas. Sections 189(a) and (c) of subpart 4 apply to 
moderate nonattainment areas and include the following: (1) An approved 
permit program for construction of new and modified major stationary 
sources (section 189(a)(1)(A)); (2) an attainment demonstration 
(section 189(a)(1)(B)); (3) provisions for RACM (section 189(a)(1)(C)); 
and (4) quantitative milestones demonstrating RFP toward attainment by 
the applicable attainment date (section 189(c)).
    The permit requirements of subpart 4, as contained in section 
189(a)(1)(A), refer to and apply the subpart 1 permit provisions 
requirements of sections 172 and 173 to PM10, without adding 
to them. Consequently, EPA believes that section 189(a)(1)(A) does not 
itself impose for redesignation purposes any additional requirements 
for moderate areas beyond those contained in subpart 1.\4\ In any 
event, in the context of redesignation, EPA has long relied on the 
interpretation that a fully approved nonattainment NSR program is not 
considered an applicable requirement for redesignation, provided the 
area can maintain the standard with a PSD program after redesignation. 
A detailed rationale for this view is described in the October 14, 
1994, Nichols memorandum. See also rulemakings for Detroit, Michigan 
(60 FR 12467-12468, March 7, 1995); Cleveland-Akron-Lorain, Ohio (61 FR 
20458, 20469-20470, May 7, 1996); Louisville, Kentucky (66 FR 53665, 
October 23, 2001); and Grand Rapids, Michigan (61 FR 31834-31837, June 
21, 1996).
---------------------------------------------------------------------------

    \4\ The potential effect of section 189(e) on section 
189(a)(1)(A) for purposes of evaluating this redesignation is 
discussed below.
---------------------------------------------------------------------------

    With respect to the specific attainment planning requirements under 
subpart 4,\5\ when EPA evaluates a redesignation request under either 
subpart 1 and/or 4, any area that is attaining the PM2.5 
standard is viewed as having satisfied the attainment planning 
requirements for these subparts. For redesignations, EPA has for many 
years interpreted attainment-

[[Page 45142]]

linked requirements as not applicable for areas attaining the standard. 
In the General Preamble, EPA stated that:
---------------------------------------------------------------------------

    \5\ I.e., attainment demonstration, RFP, RACM, milestone 
requirements, contingency measures.

    The requirements for RFP will not apply in evaluating a request 
for redesignation to attainment since, at a minimum, the air quality 
data for the area must show that the area has already attained. 
Showing that the State will make RFP towards attainment will, 
---------------------------------------------------------------------------
therefore, have no meaning at that point.

``General Preamble for the Interpretation of Title I of the Clean Air 
Act Amendments of 1990''; (57 FR 13498, 13564, April 16, 1992).
    The General Preamble also explained that

[t]he section 172(c)(9) requirements are directed at ensuring RFP 
and attainment by the applicable date. These requirements no longer 
apply when an area has attained the standard and is eligible for 
redesignation. Furthermore, section 175A for maintenance plans . . . 
provides specific requirements for contingency measures that 
effectively supersede the requirements of section 172(c)(9) for 
these areas.

Id.
    EPA similarly stated in its 1992 Calcagni memorandum that, ``The 
requirements for reasonable further progress and other measures needed 
for attainment will not apply for redesignations because they only have 
meaning for areas not attaining the standard.''
    It is evident that even if we were to consider the Court's January 
4, 2013, decision in NRDC v. EPA to mean that attainment-related 
requirements specific to subpart 4 should be imposed retroactively \6\ 
and thus are now past due, those requirements do not apply to an area 
that is attaining the 1997 PM2.5 standard, for the purpose 
of evaluating a pending request to redesignate the area to attainment. 
EPA has consistently enunciated this interpretation of applicable 
requirements under section 107(d)(3)(E) since the General Preamble was 
published more than twenty years ago. Courts have recognized the scope 
of EPA's authority to interpret ``applicable requirements'' in the 
redesignation context. See Sierra Club v. EPA, 375 F.3d 537 (7th Cir. 
2004).
---------------------------------------------------------------------------

    \6\ As EPA has explained above, we do not believe that the 
Court's January 4, 2013 decision should be interpreted so as to 
impose these requirements on the states retroactively. Sierra Club 
v. Whitman, supra.
---------------------------------------------------------------------------

    Moreover, even outside the context of redesignations, EPA has 
viewed the obligations to submit attainment-related SIP planning 
requirements of subpart 4 as inapplicable for areas that EPA determines 
are attaining the standard. EPA's prior ``Clean Data Policy'' 
rulemakings for the PM10 NAAQS, also governed by the 
requirements of subpart 4, explain EPA's reasoning. They describe the 
effects of a determination of attainment on the attainment-related SIP 
planning requirements of subpart 4. See ``Determination of Attainment 
for Coso Junction Nonattainment Area,'' (75 FR 27944, May 19, 2010). 
See also Coso Junction proposed PM10 redesignation, (75 FR 
36023, 36027, June 24, 2010); Proposed and Final Determinations of 
Attainment for San Joaquin Nonattainment Area (71 FR 40952, 40954-55, 
July 19, 2006; and 71 FR 63641, 63643-47 October 30, 2006). In short, 
EPA in this context has also long concluded that to require states to 
meet superfluous SIP planning requirements is not necessary and not 
required by the CAA, so long as those areas continue to attain the 
relevant NAAQS.
    EPA proposes to determine that the area has attained the 1997 
PM2.5 standard. Under its longstanding interpretation, EPA 
is proposing to determine here that the area meets the attainment-
related plan requirements of subparts 1 and 4.
    Thus, EPA is proposing to conclude that the requirements to submit 
an attainment demonstration under 189(a)(1)(B), a RACM determination 
under section 172(c)d section 189(a)(1)(c), a RFP demonstration under 
189(c)(1), and contingency measure requirements under section 172(c)(9) 
are satisfied for purposes of evaluating the redesignation request.
iii. Subpart 4 and Control of PM2.5 Precursors
    The D.C. Circuit in NRDC v. EPA remanded to EPA the two rules at 
issue in the case with instructions to EPA to re-promulgate them 
consistent with the requirements of subpart 4. EPA in this section 
addresses the Court's opinion with respect to PM2.5 
precursors. While past implementation of subpart 4 for PM10 
has allowed for control of PM10 precursors such as 
NOX from major stationary, mobile, and area sources in order 
to attain the standard as expeditiously as practicable, CAA section 
189(e) specifically provides that control requirements for major 
stationary sources of direct PM10 shall also apply to 
PM10 precursors from those sources, except where EPA 
determines that major stationary sources of such precursors ``do not 
contribute significantly to PM10 levels which exceed the 
standard in the area.''
    EPA's 1997 PM2.5 implementation rule, remanded by the 
D.C. Circuit, contained rebuttable presumptions concerning certain 
PM2.5 precursors applicable to attainment plans and control 
measures related to those plans. Specifically, in 40 CFR 51.1002, EPA 
provided, among other things, that a state was ``not required to 
address VOC [and ammonia] as . . . PM2.5 attainment plan 
precursor[s] and to evaluate sources of VOC [and ammonia] emissions in 
the State for control measures.'' EPA intended these to be rebuttable 
presumptions. EPA established these presumptions at the time because of 
uncertainties regarding the emission inventories for these pollutants 
and the effectiveness of specific control measures in various regions 
of the country in reducing PM2.5 concentrations. EPA also 
left open the possibility for such regulation of VOC and ammonia in 
specific areas where that was necessary.
    The Court in its January 4, 2013, decision made reference to both 
section 189(e) and 40 CFR 51.1002, and stated that, ``In light of our 
disposition, we need not address the petitioners' challenge to the 
presumptions in [40 CFR 51.1002] that volatile organic compounds and 
ammonia are not PM2.5 precursors, as subpart 4 expressly 
governs precursor presumptions.'' NRDC v. EPA, at 27, n.10.
    Elsewhere in the Court's opinion, however, the Court observed:

    Ammonia is a precursor to fine particulate matter, making it a 
precursor to both PM2.5 and PM10. For a 
PM10 nonattainment area governed by subpart 4, a 
precursor is presumptively regulated. See 42 U.S.C. 7513a(e) 
[section 189(e)]. Id. at 21, n.7.

    For a number of reasons, EPA believes that its proposed 
redesignation of Dayton area is consistent with the Court's decision on 
this aspect of subpart 4. First, while the Court, citing section 
189(e), stated that ``for a PM10 area governed by subpart 4, 
a precursor is `presumptively regulated,' '' the Court expressly 
declined to decide the specific challenge to EPA's 1997 
PM2.5 implementation rule provisions regarding ammonia and 
VOC as precursors. The Court had no occasion to reach whether and how 
it was substantively necessary to regulate any specific precursor in a 
particular PM2.5 nonattainment area, and did not address 
what might be necessary for purposes of acting upon a redesignation 
request.
    However, even if EPA takes the view that the requirements of 
subpart 4 were deemed applicable at the time the state submitted the 
redesignation request, and disregards the implementation rule's 
rebuttable presumptions regarding ammonia and VOC as PM2.5 
precursors, the regulatory consequence would be to consider the need 
for regulation of all precursors from any sources in the area to 
demonstrate attainment and to apply the section 189(e) provisions to 
major

[[Page 45143]]

stationary sources of precursors. In the case of the Dayton area, EPA 
believes that doing so is consistent with proposing redesignation of 
the area for the 1997 PM2.5 standard. The Dayton area has 
attained the standard without any specific additional controls of VOC 
and ammonia emissions from any sources in the area.
    Precursors in subpart 4 are specifically regulated under the 
provisions of section 189(e), which requires, with important 
exceptions, control requirements for major stationary sources of 
PM10 precursors.\7\ Under subpart 1 and EPA's prior 
implementation rule, all major stationary sources of PM2.5 
precursors were subject to regulation, with the exception of ammonia 
and VOC. Thus we must address here whether additional controls of 
ammonia and VOC from major stationary sources are required under 
section 189(e) of subpart 4 in order to redesignate the area for the 
1997 PM2.5 standard. As explained below, we do not believe 
that any additional controls of ammonia and VOC are required in the 
context of this redesignation.
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    \7\ Under either subpart 1 or subpart 4, for purposes of 
demonstrating attainment as expeditiously as practicable, a state is 
required to evaluate all economically and technologically feasible 
control measures for direct PM emissions and precursor emissions, 
and adopt those measures that are deemed reasonably available.
---------------------------------------------------------------------------

    In the General Preamble, EPA discusses its approach to implementing 
section 189(e). See 57 FR 13538-13542. With regard to precursor 
regulation under section 189(e), the General Preamble explicitly stated 
that control of VOCs under other CAA requirements may suffice to 
relieve a state from the need to adopt precursor controls under section 
189(e). 57 FR 13542. EPA in this proposal proposes to determine that 
the SIP has met the provisions of section 189(e) with respect to 
ammonia and VOCs as precursors. This proposed supplemental 
determination is based on our findings that (1) the Dayton area 
contains no major stationary sources of ammonia, and (2) existing major 
stationary sources of VOC are adequately controlled under other 
provisions of the CAA regulating the ozone NAAQS.\8\ In the 
alternative, EPA proposes to determine that, under the express 
exception provisions of section 189(e), and in the context of the 
redesignation of the area, which is attaining the 1997 annual 
PM2.5 standard, at present ammonia and VOC precursors from 
major stationary sources do not contribute significantly to levels 
exceeding the 1997 PM2.5 standard in the Dayton area. See 57 
FR 13539-42.
---------------------------------------------------------------------------

    \8\ The Dayton area has reduced VOC emissions through the 
implementation of various control programs including VOC Reasonably 
Available Control Technology regulations and various on-road and 
non-road motor vehicle control programs.
---------------------------------------------------------------------------

    EPA notes that its 1997 PM2.5 implementation rule 
provisions in 40 CFR 51.1002 were not directed at evaluation of 
PM2.5 precursors in the context of redesignation, but at SIP 
plans and control measures required to bring a nonattainment area into 
attainment of the 1997 PM2.5 NAAQS. By contrast, 
redesignation to attainment primarily requires the area to have already 
attained due to permanent and enforceable emission reductions, and to 
demonstrate that controls in place can continue to maintain the 
standard. Thus, even if we regard the Court's January 4, 2013, decision 
as calling for ``presumptive regulation'' of ammonia and VOC for 
PM2.5 under the attainment planning provisions of subpart 4, 
those provisions in and of themselves do not require additional 
controls of these precursors for an area that already qualifies for 
redesignation. Nor does EPA believe that requiring Ohio to address 
precursors differently than they have already would result in a 
substantively different outcome.
    Although, as EPA has emphasized, its consideration here of 
precursor requirements under subpart 4 is in the context of a 
redesignation to attainment, EPA's existing interpretation of subpart 4 
requirements with respect to precursors in attainment plans for 
PM10 contemplates that states may develop attainment plans 
that regulate only those precursors that are necessary for purposes of 
attainment in the area in question, i.e., states may determine that 
only certain precursors need be regulated for attainment and control 
purposes.\9\ Courts have upheld this approach to the requirements of 
subpart 4 for PM10.\10\ EPA believes that application of 
this approach to PM2.5 precursors under subpart 4 is 
reasonable. Because the Dayton area has already attained the 1997 
PM2.5 NAAQS with its current approach to regulation of 
PM2.5 precursors, EPA believes that it is reasonable to 
conclude in the context of this redesignation that there is no need to 
revisit the attainment control strategy with respect to the treatment 
of precursors. Even if the Court's decision is construed to impose an 
obligation, in evaluating this redesignation request, to consider 
additional precursors under subpart 4, it would not affect EPA's 
approval here of Ohio's request for redesignation of the Dayton area. 
In the context of a redesignation, the area has shown that it has 
attained the standard. Moreover, the state has shown and EPA is 
proposing that attainment in this area is due to permanent and 
enforceable emissions reductions on all precursors necessary to provide 
for continued attainment. It follows logically that no further control 
of additional precursors is necessary. Accordingly, EPA does not view 
the January 4, 2013, decision of the Court as precluding redesignation 
of the Dayton area to attainment for the 1997 PM2.5 NAAQS at 
this time.
---------------------------------------------------------------------------

    \9\ See, e.g., ``Approval and Promulgation of Implementation 
Plans for California--San Joaquin Valley PM-10 Nonattainment Area; 
Serious Area Plan for Nonattainment of the 24-Hour and Annual PM-10 
Standards,'' 69 FR 30006 (May 26, 2004) (approving a PM10 
attainment plan that impose controls on direct PM10 and 
NOX emissions and did not impose controls on 
SO2, VOC, or ammonia emissions).
    \10\ See, e.g., Assoc. of Irritated Residents v. EPA et al., 423 
F.3d 989 (9th Cir. 2005).
---------------------------------------------------------------------------

    In sum, even if Ohio were required to address precursors for the 
Dayton area under subpart 4 rather than under subpart 1, as interpreted 
in EPA's remanded PM2.5 implementation rule, EPA would still 
conclude that the area had met all applicable requirements for purposes 
of redesignation in accordance with section 107(d)(3)(E)(ii) and (v).
iv. Maintenance Plan and Evaluation of Precursors
    A discussion of the impact of the Court's decision on the 
maintenance plan required under sections 175A and 107(d)(3)(E)(iv) can 
be found in section IV.A.4.d.
b. The Dayton Area Has a Fully Approved Applicable SIP Under Section 
110(k) of the CAA
    Upon final approval of Ohio's comprehensive 2005 and 2008 emissions 
inventories, EPA will have fully approved the Ohio SIP for the Dayton 
area under section 110(k) of the CAA for all requirements applicable 
for purposes of redesignation. EPA may rely on prior SIP approvals in 
approving a redesignation request (See page 3 of the Calcagni 
memorandum; Southwestern Pennsylvania Growth Alliance v. Browner, 144 
F.3d 984, 989-990 (6th Cir. 1998); Wall v. EPA, 265 F.3d 426 (6th Cir. 
2001)) plus any additional measures it may approve in conjunction with 
a redesignation action. See 68 FR 25413, 25426 (May 12, 2003). Since 
the passage of the CAA of 1970, Ohio has adopted and submitted, and EPA 
has fully approved, provisions addressing various required SIP elements 
under particulate matter standards. EPA is proposing to approve Ohio's 
2005 and 2008 emissions inventories for the Dayton area as meeting the 
requirement of section 172(c)(3) of the CAA. No Dayton area SIP 
provisions are currently

[[Page 45144]]

disapproved, conditionally approved, or partially approved.
3. The Improvement in Air Quality Is Due to Permanent and Enforceable 
Reductions in Emissions Resulting From Implementation of the SIP and 
Applicable Federal Air Pollution Control Regulations and Other 
Permanent and Enforceable Reductions
    EPA finds that Ohio has demonstrated that the observed air quality 
improvement in the Dayton area is due to permanent and enforceable 
reductions in emissions resulting from implementation of the SIP, 
Federal measures, and other state-adopted measures.
    In making this showing, Ohio EPA has calculated the change in 
emissions between 2005, one of the years in the period during which the 
Dayton area monitored nonattainment, and 2008, one of the years in the 
period during which the Dayton area monitored attainment. The reduction 
in emissions and the corresponding improvement in air quality over this 
time period can be attributed to a number of regulatory control 
measures that the Dayton area and upwind areas have implemented in 
recent years.
a. Permanent and Enforceable Controls Implemented
    The following is a discussion of permanent and enforceable measures 
that have been implemented in the area:
i. Federal Emission Control Measures
    Reductions in fine particle precursor emissions have occurred 
statewide and in upwind areas as a result of Federal emission control 
measures, with additional emission reductions expected to occur in the 
future. Federal emission control measures include the following:
    Tier 2 Emission Standards for Vehicles and Gasoline Sulfur 
Standards. These emission control requirements result in lower VOC, 
NOX, and SO2 emissions from new cars and light 
duty trucks, including sport utility vehicles. The Federal rules were 
phased in between 2004 and 2009. The EPA has estimated that, by the 
time post-2009 vehicles have entirely replaced pre-2009 vehicles, the 
following vehicle NOX emission reductions will have occurred 
nationwide: Passenger cars (light duty vehicles) (77 percent); light 
duty trucks, minivans, and sports utility vehicles (86 percent); and, 
larger sports utility vehicles, vans, and heavier trucks (69 to 95 
percent). Some of the emissions reductions resulting from new vehicle 
standards occurred during the 2008-2010 attainment period; however 
additional reductions will continue to occur throughout the maintenance 
period as new vehicles replace older vehicles. The Tier 2 standards 
also reduced the sulfur content of gasoline to 30 parts per million 
(ppm) beginning in January 2006. Gasoline sold in the region including 
Ohio prior to implementation of the Tier 2 sulfur content limits had an 
average sulfur content of 276 ppm.\11\
---------------------------------------------------------------------------

    \11\ See Regulatory Impact Analysis--Control of Air Pollution 
from New Motor Vehicles: Tier 2 Motor Vehicle Emissions Standards 
and Gasoline Sulfur Control Requirements, December 1999, EPA420-R-
99-023, p. IV-42.
---------------------------------------------------------------------------

    Heavy-Duty Diesel Engine Rule. This rule, which EPA issued in July 
2000, limited the sulfur content of diesel fuel beginning in 2004. A 
second phase took effect in 2007 which reduced fine particle emissions 
from heavy-duty highway engines and further reduced the highway diesel 
fuel sulfur content to 15 ppm. The total program is estimated to 
achieve a 90 percent reduction in primary PM2.5 emissions 
and a 95 percent reduction in NOX emissions for these new 
engines using low sulfur diesel, compared to existing engines using 
higher sulfur content diesel. The reductions in fuel sulfur content 
occurred by the 2008-2010 attainment period. Some of the emissions 
reductions resulting from new vehicle standards occurred during the 
2008-2010 attainment period, however additional reductions will 
continue to occur throughout the maintenance period as the fleet of 
older heavy duty diesel engines turns over. The reduction in fuel 
sulfur content also yielded an immediate reduction in sulfate particle 
emissions from all diesel vehicles.
    Nonroad Diesel Rule. In May 2004, EPA promulgated a new rule for 
large nonroad diesel engines, such as those used in construction, 
agriculture, and mining equipment, which established engine emission 
standards to be phased in between 2008 and 2014. The rule also required 
reductions to the sulfur content in nonroad diesel fuel by over 99 
percent. Prior to 2006, nonroad diesel fuel averaged approximately 
3,400 ppm sulfur. This rule limited nonroad diesel sulfur content to 
500 ppm by 2006, with a further reduction to 15 ppm, by 2010. The 
combined engine and fuel rules will reduce NOX and PM 
emissions from large nonroad diesel engines by over 90 percent, 
compared to current nonroad engines using higher sulfur content diesel. 
The reduction in fuel sulfur content yielded an immediate reduction in 
sulfate particle emissions from all diesel vehicles. In addition, some 
emissions reductions from the new engine emission standards were 
realized over the 2008-2010 time period, although most of the 
reductions will occur over the maintenance period as the fleet of older 
nonroad diesel engines turns over.
    Nonroad Large Spark-Ignition Engine and Recreational Engine 
Standards. In November 2002, EPA promulgated emission standards for 
groups of previously unregulated nonroad engines. These engines include 
large spark-ignition engines such as those used in forklifts and 
airport ground-service equipment; recreational vehicles using spark-
ignition engines such as off-highway motorcycles, all-terrain vehicles, 
and snowmobiles; and recreational marine diesel engines. Emission 
standards from large spark-ignition engines were implemented in two 
tiers, with Tier 1 starting in 2004 and Tier 2 in 2007. Recreational 
vehicle emission standards are being phased in from 2006 through 2012. 
Marine Diesel engine standards were phased in from 2006 through 2009. 
With full implementation of all of the nonroad spark-ignition engine 
and recreational engine standards, an overall 72 percent reduction in 
VOC, 80 percent reduction in NOX and 56 percent reduction in 
carbon monoxide (CO) emissions are expected by 2020. Some of these 
emission reductions occurred by the 2008-2010 attainment period and 
additional emission reductions will occur during the maintenance period 
as the fleet turns over.
ii. Control Measures Implemented in Ohio and in Upwind Areas
    Given the significance of sulfates and nitrates in the Dayton area, 
the area's air quality is strongly affected by regulation of 
SO2 and NOX emissions from power plants.
    NOX SIP Call. On October 27, 1998 (63 FR 57356), EPA issued a 
NOX SIP Call requiring the District of Columbia and 22 
states to reduce emissions of NOX. Affected states were 
required to comply with Phase I of the SIP Call beginning in 2004, and 
Phase II beginning in 2007. Emission reductions resulting from 
regulations developed in response to the NOX SIP Call are 
permanent and enforceable.
    CAIR and CSAPR. EPA promulgated CSAPR (76 FR 48208, August 8, 
2011), to replace CAIR, which has been in place since 2005. See 76 FR 
59517. CAIR requires significant reductions in emissions of 
SO2 and NOX from electric generating units to 
limit the interstate transport of these pollutants and the ozone and 
fine particulate matter they form in the atmosphere. See 76 FR 70093. 
The D.C. Circuit initially vacated CAIR, North Carolina v. EPA, 531 
F.3d 896 (D.C. Cir. 2008), but ultimately

[[Page 45145]]

remanded that rule to EPA without vacatur to preserve the environmental 
benefits provided by CAIR, North Carolina v. EPA, 550 F.3d 1176, 1178 
(D.C. Cir. 2008).
    On December 30, 2011, the D.C. Circuit issued an order addressing 
the status of CSAPR and CAIR in response to motions filed by numerous 
parties seeking a stay of CSAPR pending judicial review. In that order, 
the Court stayed CSAPR pending resolution of the petitions for review 
of that rule in EME Homer City Generation, L.P. v. EPA (No. 11-1302 and 
consolidated cases). The Court also indicated that EPA was expected to 
continue to administer CAIR in the interim until judicial review of 
CSAPR was completed.
    As noted above, on August 21, 2012, the D.C. Circuit issued the 
decision in EME Homer City to vacate and remand CSAPR and ordered EPA 
to continue administering CAIR ``pending . . . development of a valid 
replacement.'' EME Homer City at 38. The D.C. Circuit denied all 
petitions for rehearing on January 24, 2013. EPA and other parties have 
filed petitions for certiorari to the U.S. Supreme Court. On June 24, 
2013, the Supreme Court granted certiorari and agreed to review the 
D.C. Circuit's decision in EME Homer City. The Supreme Court's grant of 
certiorari, by itself, does not alter the status of CAIR or CSAPR. At 
this time, CAIR remains in place.
    In light of these unique circumstances and for the reasons 
explained below, to the extent that attainment is due to emission 
reductions associated with CAIR, EPA is here determining that those 
reductions are sufficiently permanent and enforceable for purposes of 
CAA sections 107(d)(3)(E)(iii) and 175A.
    As directed by the D.C. Circuit, CAIR remains in place and 
enforceable until EPA promulgates a valid replacement rule to 
substitute for CAIR. The Dayton SIP revision lists CAIR as a control 
measure that was adopted by the State in 2006 and required compliance 
by January 1, 2009. CAIR was thus in place and getting emission 
reductions when Dayton monitored attainment of the 1997 annual 
PM2.5 standard during the 2006-2008 time period. The 
quality-assured, certified monitoring data continues to show the area 
in attainment of the 1997 PM2.5 standard through 2012.
    To the extent Ohio is relying on CAIR in its maintenance plan to 
support continued attainment into the future, the directive from the 
D.C. Circuit in EME Homer City ensures that the reductions associated 
with CAIR will be permanent and enforceable for the necessary time 
period. EPA has been ordered by the Court to develop a new rule to 
address interstate transport to replace CSAPR, and the opinion makes 
clear that after promulgating that new rule EPA must provide states an 
opportunity to draft and submit SIPs to implement that rule. Thus, CAIR 
will remain in place until EPA has promulgated a final rule through a 
notice-and-comment rulemaking process, states have had an opportunity 
to draft and submit SIPs in response to it, EPA has reviewed the SIPs 
to determine if they can be approved, and EPA has taken action on the 
SIPs, including promulgating a FIP if appropriate. The Court's clear 
instruction to EPA is that it must continue to administer CAIR until a 
valid replacement exists, and thus EPA believes that CAIR emission 
reductions may be relied upon until the necessary actions are taken by 
EPA and states to administer CAIR's replacement. Furthermore, the 
Court's instruction provides an additional backstop: By definition, any 
rule that replaces CAIR and meets the Court's direction would require 
upwind states to have SIPs that eliminate any significant contributions 
to downwind nonattainment and prevent interference with maintenance in 
downwind areas.
    Further, in vacating CSAPR and requiring EPA to continue 
administering CAIR, the D.C. Circuit emphasized that the consequences 
of vacating CAIR ``might be more severe now in light of the reliance 
interests accumulated over the intervening four years.'' EME Homer 
City, 696 F.3d at 38. The accumulated reliance interests include the 
interests of states that reasonably assumed they could rely on 
reductions associated with CAIR which brought certain nonattainment 
areas into attainment with the NAAQS. If EPA were prevented from 
relying on reductions associated with CAIR in redesignation actions, 
states would be forced to impose additional, redundant reductions on 
top of those achieved by CAIR. EPA believes this is precisely the type 
of irrational result the Court sought to avoid by ordering EPA to 
continue administering CAIR. For these reasons also, EPA believes it is 
appropriate to allow states to rely on CAIR, and the existing emissions 
reductions achieved by CAIR, as sufficiently permanent and enforceable 
for regulatory purposes such as redesignations. Following promulgation 
of the replacement rule for CSAPR, EPA will review existing SIPs as 
appropriate to identify whether there are any issues that need to be 
addressed.
b. Emission Reductions
    Ohio developed emissions inventories for NOX, primary 
PM2.5, and SO2 for 2005, a year that the Dayton 
area monitored nonattainment of the 1997 annual PM2.5 
standard, and 2008, a year the area monitored attainment of the 
standard. The emission inventories were developed with the assistance 
of the Lake Michigan Air Directors Consortium (LADCO). The 2005 
nonattainment inventory was developed as described below. Point source 
emissions for 2005 were compiled by Ohio EPA using source specific data 
reported by facilities through the State's STARShip database program. 
The data are reported by facilities annually and include emissions, 
process rates, operating schedules, emissions control data and other 
relevant information. Ohio EPA quality assured the database files and 
submitted the data to LADCO for emissions processing through the 
Emissions Modeling System (EMS). LADCO used the EGU inventory compiled 
by EPA's Acid Rain Program, based on facility reported emissions as 
measured by continuous emissions monitors.
    Area source sector emissions were calculated using surrogate 
emissions factors based on energy usage, population, employment 
records, or other reliable data. Ohio EPA used Emission Inventory 
improvement Program methodologies or selected other methodologies which 
are shared by other states. The decision of which methodology to use 
was largely based on Ohio's data availability.
    Nonroad source sector emissions estimates were generated using 
EPA's National Mobile Inventory Model (NMIM), with the following 
modifications: Emission factors were added for diesel tampers/rammers; 
the PM2.5 ratios in the SCC table were revised to correctly 
calculate PM2.5 diesel emissions; and, gasoline parameters, 
including Reid Vapor Pressure (RVP), Oxygenate content and sulfur 
content, were revised using updates provided by the state and E.H. 
Pechan and Associates. Marine, aircraft and rail nonroad emissions were 
calculated separately. Contractors were employed by LADCO to estimate 
emissions for commercial marine vessels and railroads. Ohio developed 
aircraft emissions estimates using AP-42 emission factors and landing 
and take-off data provided by the Federal Aviation Administration.
    Onroad mobile source emissions estimates were developed using the 
EPA's MOVES2010 model. The 2008 attainment year inventory was

[[Page 45146]]

developed as follows. Point source emissions for 2008 were compiled 
from Ohio's STARShip database. Onroad emissions projections were based 
on EPA's MOVES2010 model. Area and nonroad emissions were grown from 
the 2005 inventory using LADCO's growth factors.
    The state aggregated the emission inventories to obtain the total 
emissions for each category and the grand total emissions for the 
Dayton area. The emission inventories for the Dayton area by pollutant 
are presented in Tables 2 to 4. The data in Table 2 indicates 
PM2.5 emission decreased by 170 tons per year (tpy) between 
2005 and 2008. Similarly, the Table 3 data indicates a 7,022 tpy 
reduction in NOX emissions and Table 4 shows a 1,415 tpy 
decrease in SO2 emission from 2005 to 2008.
4. The Area Has a Fully Approved Maintenance Plan Pursuant to Section 
175A of the CAA.
    In conjunction with Ohio's requests to redesignate the Dayton 
nonattainment area to attainment status, Ohio EPA submitted SIP 
revisions to provide for maintenance of the 1997 annual 
PM2.5 NAAQS in the area through 2022.
a. What is required in a maintenance plan?
    Section 175A of the CAA sets forth the required elements of a 
maintenance plan for areas seeking redesignation from nonattainment to 
attainment. Under section 175A, the plan must demonstrate continued 
attainment of the applicable NAAQS for at least ten years after EPA 
approves a redesignation to attainment. Eight years after 
redesignation, the state must submit a revised maintenance plan which 
demonstrates that attainment will continue to be maintained for ten 
years following the initial ten year maintenance period. To address the 
possibility of future NAAQS violations, the maintenance plan must 
contain contingency measures with a schedule for implementation as EPA 
deems necessary to assure prompt correction of any future 
PM2.5 violations.
    The September 4, 1992, John Calcagni memorandum provides additional 
guidance on the content of a maintenance plan. The memorandum states 
that a maintenance plan should address the following items: The 
attainment emissions inventories, a maintenance demonstration showing 
maintenance for the ten years of the maintenance period, a commitment 
to maintain the existing monitoring network, factors and procedures to 
be used for verification of continued attainment of the NAAQS, and a 
contingency plan to prevent or correct future violations of the NAAQS.
b. Attainment Inventory
    Ohio developed emissions inventories for NOX, 
PM2.5, and SO2 for 2008, a year the area 
monitored attainment of the 1997 annual PM2.5 standard, as 
described in section IV.A.3.b. The attainment level of emissions is 
summarized in Tables 2 to 4.
c. Demonstration of Maintenance
    Along with the redesignation requests, Ohio EPA submitted revisions 
to the Ohio PM2.5 SIP to include maintenance plans for the 
Dayton area, as required by section 175A of the CAA. Section 175A 
requires a state seeking redesignation to attainment to submit a SIP 
revision to provide for the maintenance of the NAAQS in the area ``for 
at least 10 years after the redesignation.'' EPA has interpreted this 
as a showing of maintenance ``for a period of ten years following 
redesignation'' in the Calcagni Memorandum, p. 9. Where the emissions 
inventory method of showing maintenance is used, its purpose is to show 
that emissions during the maintenance period will not increase over the 
attainment year inventory. Calcagni Memorandum, pp. 9-10.
    Ohio's maintenance plan submissions expressly document that the 
Dayton area's emissions inventories will remain below the attainment 
year inventories through 2022. In addition, for the reasons set forth 
below, EPA believes that Ohio's submission, in conjunction with 
additional supporting information, further demonstrating that the area 
will continue to maintain the PM2.5 standard at least 
through 2023. Thus, if EPA finalizes its proposed approval of the 
redesignation requests and maintenance plans in 2013, it will be based 
on a showing, in accordance with section 175A, that Ohio's maintenance 
plans provide for maintenance for at least ten years after 
redesignation.
    Ohio's plans demonstrate maintenance of the PM2.5 NAAQS 
through 2022 by showing that current and future emissions of 
NOX, PM2.5, and SO2 for the Dayton 
area remain at or below attainment year emission levels. A maintenance 
demonstration need not be based on modeling. See Wall v. EPA, 265 F.3d 
426 (6th Cir. 2001), Sierra Club v. EPA, 375 F. 3d 537 (7th Cir. 2004). 
See also 66 FR 53094, 53099-53100 (October 19, 2001), 68 FR 25413, 
25430-25432 (May 12, 2003). As discussed below, a comparison of current 
and future VOC and ammonia emissions show ammonia emissions are 
expected to remain relatively constant. In contrast, VOC emissions are 
projected to decline significantly. The VOC and ammonia emission 
projections further support a finding that the Dayton area will 
continue to maintain the standard.
    Ohio is using PM2.5, NOX, and SO2 
emissions inventory projections for the years 2015 and 2022 to 
demonstrate maintenance. The projected emissions were estimated by Ohio 
with assistance from LADCO.
    LADCO has developed growth and control files for point, area, and 
nonroad categories. These files were used along with LADCO's 2009 and 
2018 emission inventories to develop the 2015 and 2022 emissions 
estimates. Onroad emissions projections were made by using the MOVES 
model.
    As discussed in section IV.3.a., many of the control programs that 
helped to bring the area into attainment of the standard will continue 
to achieve additional emission reductions over the maintenance period. 
These control programs include Tier 2 emission standards for vehicles 
and gasoline sulfur standards, the heavy-duty diesel engine rule, the 
nonroad diesel rule, and the nonroad large spark-ignition engine and 
recreation engine standards. In addition, implementation of CAIR was 
assumed in the projections. The state then aggregated the emission 
inventories to obtain the total emissions for each category and the 
grand total emissions for the Dayton area. The emission inventories for 
the Dayton area by pollutant are presented in Tables 2 to 4.

  Table 2--Comparison of 2005, 2008, 2015, and 2022 Direct PM2.5 Emission Totals by County (tpy) for the Dayton
                                                      Area
----------------------------------------------------------------------------------------------------------------
                                                                   Direct PM2.5
                                 -------------------------------------------------------------------------------
             County                                    2008                            2022         Net change
                                     2005 Base      Attainment         2015         Maintenance      2008-2022
----------------------------------------------------------------------------------------------------------------
Clark...........................          377.44          340.97          248.54          198.10         -142.87

[[Page 45147]]

 
Greene..........................          491.15          458.91          372.82          336.44         -122.47
Montgomery......................        1,516.57        1,415.40        1,115.14          968.50         -446.90
                                 -------------------------------------------------------------------------------
    Total.......................           2,385           2,215           1,737           1,503            -712
----------------------------------------------------------------------------------------------------------------

    Table 3--Comparison of 2005, 2008, 2015, and 2022 NOX Emission Totals by County (tpy) for the Dayton Area
----------------------------------------------------------------------------------------------------------------
                                                                        NOX
                                 -------------------------------------------------------------------------------
             County                                    2008                            2022         Net change
                                     2005 Base      Attainment         2015         Maintenance      2008-2022
----------------------------------------------------------------------------------------------------------------
Clark...........................        7,327.18        6,159.66        3,630.30        2,080.20       -4,079.46
Greene..........................        9,448.97        8,459.44        6,140.94        5,014.57       -3,444.87
Montgomery......................       27,364.92       22,499.86       14,004.55        8,762.54       -13,737.3
                                 -------------------------------------------------------------------------------
    Total.......................          44,141          37,119          23,776          15,857         -21,262
----------------------------------------------------------------------------------------------------------------

    Table 4--Comparison of 2005, 2008, 2015, and 2022 SO2 Emission Totals by County (tpy) for the Dayton Area
----------------------------------------------------------------------------------------------------------------
                                                                        SO2
                                 -------------------------------------------------------------------------------
             County                                    2008                            2022         Net change
                                     2005 Base      Attainment         2015         Maintenance      2008-2022
----------------------------------------------------------------------------------------------------------------
Clark...........................          278.81          168.87          121.64          109.97          -58.90
Greene..........................        2,344.19        2,278.89        2,352.21        2,397.31         +118.42
Montgomery......................        8,653.40        7,413.46        7,360.15        7,053.08         -360.38
                                 -------------------------------------------------------------------------------
    Total.......................          11,276           9,861           9,834           9,560            -301
----------------------------------------------------------------------------------------------------------------

    The 2015 and 2022 emission inventories indicate that the emission 
reductions are expected to continue. A 712 tpy, or 32 percent, 
reduction in PM2.5 emissions between 2008 and 2022 is 
expected. The 21,262 tpy NOX emission decrease is a 57 
percent reduction, while the 301 tpy SO2 decrease equates to 
a 3 percent reduction, again between 2008 and 2022. These rates of 
decline are consistent with monitored and projected air quality trends, 
emissions reductions achieved through emissions controls and 
regulations that will remain in place beyond 2023. Furthermore, fleet 
turnover in onroad and nonroad vehicles that will continue to occur 
after 2022 will continue to provide additional significant emission 
reductions.
    In addition, available air quality modeling analyses show continued 
maintenance of the standard during the maintenance period. The current 
air quality design value for the Dayton area is 12.3 [mu]g/m\3\ based 
on 2010 to 2012 air quality data, which is well below the 1997 annual 
PM2.5 NAAQS of 15 [mu]g/m\3\. Moreover, the modeling 
analysis conducted for EPA's regulatory impact analysis (RIA) for the 
2012 PM2.5 NAAQS indicates that the design value for this 
area is expected to continue through 2020. In the RIA analysis, the 
2020 modeled design value for the Dayton area is 9.5 [mu]g/m\3\. Given 
that precursor emissions are projected to decrease through 2022, it is 
reasonable to conclude that monitored PM2.5 levels in this 
area will also continue to decrease through 2022.
    Based on the information summarized above, Ohio has adequately 
demonstrated maintenance of the PM2.5 standard for a period 
extending ten years from the date that EPA may be expected to complete 
rulemaking on the State's redesignation request.
d. Maintenance Plan and Evaluation of Precursors
    After evaluating the effect of the Court's remand of EPA's 
implementation rule, a rule that included presumptions against 
consideration of VOC and ammonia as PM2.5 precursors, EPA in 
this proposal is also considering the impact of the decision on the 
maintenance plan required under sections 175A and 107(d)(3)(E)(iv). To 
begin with, EPA notes that the area has attained the 1997 
PM2.5 standard and that the state has shown that attainment 
of that standard is due to permanent and enforceable emission 
reductions.
    Based on its review of Ohio's maintenance plan and related 
information, EPA believes that the primary influences on future air 
quality in the Dayton area will be emissions of NOX, 
directly emitted PM2.5, and SO2. EPA therefore 
proposes to determine that Ohio's maintenance plan shows continued 
maintenance of the standard by tracking the levels of the precursors 
whose control brought about attainment of the 1997 PM2.5 
standard in the Dayton area. Nevertheless, pursuant to the Court's 
January 4, 2013, decision, EPA is further assessing the potential role 
of VOC and ammonia in achieving continued maintenance in this area. As 
explained below, based upon documentation provided by the State

[[Page 45148]]

and supporting information, EPA believes that the prospective trends in 
emissions of VOC and ammonia are consistent with a finding of continued 
maintenance of the standard in the Dayton area.
    First, as noted above in EPA's discussion of section 189(e), VOC 
emission levels in this area have historically been well controlled 
under SIP requirements related to ozone and other pollutants. Second, 
total ammonia emissions throughout the Dayton area are modest, 
estimated to be about 27,250 tpy. See Table 5. Third, as described 
below, available information shows that no precursor, including VOC and 
ammonia, is expected to increase over the maintenance period so as to 
interfere with or undermine the Ohio's maintenance demonstration.
    Ohio's maintenance plan shows that emissions of direct 
PM2.5, SO2, and NOX are projected to 
decrease by 712 tpy, 301 tpy, and 21,262 tpy, respectively, over the 
maintenance period. See Tables 2 to 4. In addition, emissions 
inventories used in the RIA for the 2012 PM2.5 NAAQS show 
that VOC and ammonia emissions are projected to decrease by 124 tpy and 
8,778 tpy, respectively between 2007 and 2020 as shown on Table 5. 
While the RIA emissions inventories are only projected out to 2020, 
there is no reason to believe that this downward trend would not 
continue through 2023. Given that the Dayton area is already attaining 
the 1997 PM2.5 NAAQS even with the current level of 
emissions from sources in the area, the downward trend of emissions 
inventories would be consistent with continued attainment. Indeed, 
projected emissions reductions for the precursors that Ohio is 
addressing for purposes of the 1997 PM2.5 NAAQS indicate 
that the area should continue to attain the NAAQS following the control 
strategy that the state has already elected to pursue. Even if VOC and 
ammonia emissions were to increase unexpectedly between 2020 and 2022, 
the overall emissions reductions projected in direct PM2.5, 
SO2, and NOX would be sufficient to offset any 
increases. For these reasons, EPA believes that local emissions of all 
of the potential PM2.5 precursors will not increase to the 
extent that they will cause monitored PM2.5 levels to 
violate the 1997 PM2.5 standard during the maintenance 
period.

                      Table 5--Comparison of 2007 and 2020 VOC and Ammonia Emission Totals by County (tpy) for the Dayton Area \12\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Ammonia                                           VOC
                                                         -----------------------------------------------------------------------------------------------
                         County                                                             Net change                                      Net change
                                                               2007            2020          2007-2020         2007            2020          2007-2020
--------------------------------------------------------------------------------------------------------------------------------------------------------
Clark...................................................             808             793             -15           4,771           3,142          -1,629
Greene..................................................             537             525             -13           4,052           2,749          -1,303
Montgomery..............................................             748             651             -96          18,421          12,574          -5,846
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................           2,093           1,969            -124          27,244          18,465          -8,778
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Thus,  EPA believes that there is ample justification to conclude 
that the Dayton area should be redesignated, even taking into 
consideration the emissions of other precursors potentially relevant to 
PM2.5. After consideration of the D.C. Circuit's January 4, 
2013, decision, and for the reasons set forth in this notice, EPA 
proposes to approve Ohio's maintenance plan.
---------------------------------------------------------------------------

    \12\ These emissions estimates were taken from the emissions 
inventories developed for the RIA for the 2012 PM2.5 
NAAQS. Values were rounded on the table following making the 
calculations.
---------------------------------------------------------------------------

e. Monitoring Network
    Ohio currently operates three monitors for purposes of determining 
attainment with the PM2.5 standards in the Dayton area. Ohio 
EPA has committed to continue to operate and maintain these monitors 
and will consult with EPA prior to making any changes to the existing 
monitoring network. Ohio EPA remains obligated to continue to quality 
assure monitoring data in accordance with 40 CFR part 58 and enter all 
data into the AQS in accordance with Federal guidelines.
f. Verification of Continued Attainment
    Continued attainment of the PM2.5 NAAQS in the Dayton 
area depends, in part, on Ohio's efforts toward tracking indicators of 
continued attainment during the maintenance period. Ohio's plans for 
verifying continued attainment of the 1997 annual PM2.5 
standard in the Dayton area consists of continued ambient 
PM2.5 monitoring in accordance with the requirements of 40 
CFR part 58. Ohio will also continue to develop and submit periodic 
emission inventories as required by the Federal Consolidated Emissions 
Reporting Rule (codified at 40 CFR 51 subpart A) to track future levels 
of emissions.
g. Contingency Plan
    The contingency plan provisions are designed to promptly correct or 
prevent a violation of the NAAQS that might occur after redesignation 
of an area to attainment. Section 175A of the CAA requires that a 
maintenance plan include such contingency measures as EPA deems 
necessary to ensure that the state will promptly correct a violation of 
the NAAQS that occurs after redesignation. The maintenance plan should 
identify the contingency measures to be adopted, a schedule and 
procedure for adoption and implementation of the contingency measures, 
and a time limit for action by the state. The state should also 
identify specific indicators to be used to determine when the 
contingency measures need to be adopted and implemented. The 
maintenance plan must include a requirement that the state will 
implement all measures with respect to control of the pollutant(s) that 
were contained in the SIP before redesignation of the area to 
attainment. See section 175A(d) of the CAA.
    As required by section 175A of the CAA, Ohio has adopted 
contingency plans for the Dayton area to address possible future 
PM2.5 air quality problems. Contingency provisions are 
measures that can be implemented to prevent or promptly correct a 
violation of the standard. The state set a ``warning level'' for when 
an annual mean of 15.5 [micro]g/m\3\ or greater occurs. This level 
requires analyzing the ambient concentration trend within 12 months of 
the warning level triggering calendar year's end.
    If the annual value trend is rising, control measures to reverse 
the rising trend are implemented. An ``action level'' response is 
triggered whenever the two year average is 15.0 [micro]g/m\3\ or

[[Page 45149]]

greater and whenever a violation occurs. This level response requires 
the state, along with the Regional Air Pollution Control Agency, to 
determine the additional control measures to assure future attainment. 
The controls measures are to be in place within 18 months from the end 
of the calendar year prompting the action level.
    Ohio provided a list of potential contingency provisions in its 
maintenance plan. It listed diesel emission reductions, alternative 
fuels, fleet diesel retrofit programs, tighter PM2.5, 
SO2, and NOX emission offsets for new and 
modified major sources, upgraded wet suppression at scrap yards and at 
concrete manufacturing facilities, and additional NOX RACT 
measures. Other controls measures may also be implemented. If 
necessary, Ohio will select control measures to ensure the ambient 
PM2.5 concentrations remain in attainment with the standard.
h. Provisions for Future Updates of the Annual PM2.5 
Maintenance Plan
    As required by section 175A(b) of the CAA, Ohio commits to submit 
to EPA updated maintenance plans eight years after redesignation of the 
Dayton area to attainment of the 1997 annual PM2.5 standard 
to cover an additional ten year period beyond the initial ten year 
maintenance period. As required by section 175A of the CAA, Ohio has 
committed to retain the control measures contained in the SIP prior to 
redesignation, and to submit to EPA for approval as a SIP revision, any 
changes to its rules or emission limits applicable to SO2, 
NOX, or direct PM2.5 sources as required for 
maintenance of the 1997 annual PM2.5 standard in the Dayton 
area.
    EPA has concluded that the maintenance plan adequately addresses 
the five basic components of a maintenance plan: Attainment inventory, 
maintenance demonstration, monitoring network, verification of 
continued attainment, and a contingency plan.

B. Comprehensive Emissions Inventories

    Section 173(c)(3) of the CAA requires areas to submit a 
comprehensive, accurate and current emissions inventory. As part of the 
redesignation request, Ohio submitted 2005 and 2008 emissions 
inventories for NOX, primary PM2.5, and 
SO2 on June 1, 2011. These emission inventories are 
discussed in section IV.A.4.c. and the data are shown in Tables 2 to 4.
    On April 30, 2013, Ohio supplemented its emissions inventory 
information for direct PM2.5, NOX, and 
SO2 with 2007/2008 emissions inventories for ammonia and 
VOC. The additional emissions inventory information provided by Ohio 
addresses emissions of VOC and ammonia from the general source 
categories of point sources, area sources, onroad mobile sources, and 
nonroad mobile sources. The emissions inventories were based upon 
information generated by LADCO in conjunction with its member states.
    As with its inventories for NOX, directly emitted 
PM2.5, and SO2, Ohio's inventories for point 
source emissions of VOC and ammonia were based largely on LADCO runs 
with the EMS model using data provided by the State of Ohio. The point 
source data supplied by the State was obtained from facility emissions 
reporting.
    For area sources inventories for VOC and ammonia, again as with the 
inventories for NOX, PM2.5, and SO2, 
LADCO ran the EMS model using the 2008 National Emissions Inventory 
(NEI) data provided by Ohio. LADCO followed Eastern Regional Technical 
Advisory Committee (ERTAC) recommendations on area sources when 
preparing the data. Agricultural ammonia emissions were not taken from 
NEI; instead emissions were based on Carnegie Mellon University's 
Ammonia Emission Inventory for the Continental United States (CMU). 
Specifically, the CMU 2002 annual emissions were grown to reflect 2007 
conditions. A process-based ammonia emissions model developed for LADCO 
was then used to develop temporal factors to reflect the impact of 
average meteorology on livestock emissions.
    Non-road mobile source emissions of VOC and ammonia, similar to the 
other pollutants, were estimated using the NMIM2008 emissions model. 
LADCO also accounted for three other non-road categories not covered by 
the NMIM model: Commercial marine vessels, aircraft, and railroads. 
Marine emissions were based on reports prepared by Environ entitled 
``LADCO Nonroad Emissions Inventory Project for Locomotive, Commercial 
Marine, and Recreational Marine Emission Sources, Final Report, 
December 2004'' and ``LADCO 2005 Commercial Marine Emissions, Draft, 
March, 2, 2007.'' Aircraft emissions were provided by Ohio and 
calculated using AP-42 emission factors and landing and take-off data 
provided by the Federal Aviation Administration. Rail emissions were 
based on the 2008 inventory developed by ERTAC. On-road mobile source 
emissions were generated using EPA's MOVES2010a emissions model.
    EPA notes that the emissions inventory developed by LADCO is 
documented in ``Regional Air Quality Analyses for Ozone, 
PM2.5, and Regional Haze: Base C Emissions Inventory'' 
(September 12, 2011). EPA has concluded that the 2007/2008 ammonia and 
VOC emissions inventories provided by Ohio are complete and as accurate 
as possible given the input data available for the relevant source 
categories. Ohio submitted an 2007/2008 ammonia inventory of 2,286 tpy 
and a 25,881 tpy VOC 2007/2008 inventory.\13\ EPA also believes that 
these inventories provide information about VOC and ammonia as 
PM2.5 precursors in the context of evaluating redesignation 
of the Dayton area under subpart 4.
---------------------------------------------------------------------------

    \13\ These ammonia and VOC emissions inventories vary from the 
inventories presented on Table 5 in section IV.A.4.d. because cover 
different time periods, only 2007 versus 2007 and 2008.
---------------------------------------------------------------------------

    Therefore, we are proposing to approve the ammonia and VOC 
emissions inventories submitted by Ohio in April 2013, in conjunction 
with the NOX, direct PM2.5, and SO2 
emissions inventories submitted in June 2011, as fully meeting the 
comprehensive inventory requirement of section 172(c)(3) of the CAA for 
the Dayton area for the 1997 annual PM2.5 standard.

C. Motor Vehicle Emission Budgets (MVEBs)

1. How are MVEBs developed?
    Under the CAA, states are required to submit, at various times, 
control strategy SIP revisions and maintenance plans for nonattainment 
areas and for areas seeking redesignation to attainment for a given 
NAAQS. These emission control strategy SIP revisions (e.g., RFP and 
attainment demonstration SIP revisions) and maintenance plans create 
MVEBs based on onroad mobile source emissions for the relevant criteria 
pollutants and/or their precursors, where appropriate, to address 
pollution from onroad transportation sources. The MVEBs are the 
portions of the total allowable emissions that are allocated to onroad 
vehicle use that, together with emissions from all other sources in the 
area, will provide for attainment, RFP, or maintenance, as applicable. 
The budget serves as a ceiling on emissions from an area's planned 
transportation system. Under 40 CFR part 93, a MVEB for an area seeking 
a redesignation to attainment is established for the last year of the 
maintenance plan. See the September 27, 2011, notice of direct final 
approval for a more complete discussion of MVEBs. (76 FR 59512).
    Under section 176(c) of the CAA, transportation plans and 
transportation improvement programs (TIPs) must be

[[Page 45150]]

evaluated to determine if they conform with the area's SIP. Conformity 
to the SIP means that transportation activities will not cause new air 
quality violations, worsen existing air quality violations, or delay 
timely attainment of the NAAQS or any required interim milestone. If a 
transportation plan or TIP does not conform, most new transportation 
projects that would expand the capacity of roadways cannot go forward. 
Regulations at 40 CFR part 93 set forth EPA policy, criteria, and 
procedures for demonstrating and assuring conformity of such 
transportation activities to a SIP.
    When reviewing SIP revisions containing MVEBs, including attainment 
strategies, rate-of-progress plans, and maintenance plans, EPA must 
affirmatively find ``adequate'' or approve for use in determining 
transportation conformity before the MVEBs can be used. Once EPA 
affirmatively approves or finds the submitted MVEBs to be adequate for 
transportation conformity purposes, the MVEBs must be used by state and 
Federal agencies in determining whether transportation plans and TIPs 
conform to the SIP as required by section 176(c) of the CAA. EPA's 
substantive criteria for determining the adequacy of MVEBs are set out 
in 40 CFR 93.118(e)(4). Additionally, to approve a motor vehicle 
emissions budget EPA must complete a thorough review of the SIP, in 
this case the PM2.5 maintenance plan, and conclude that the 
SIP will achieve its overall purpose, in this case providing for 
maintenance of the 1997 annual PM2.5 standard.
    EPA's process for determining adequacy of a MVEB consists of three 
basic steps: (1) Providing public notification of a SIP submission; (2) 
providing the public the opportunity to comment on the MVEB during a 
public comment period; and, (3) EPA taking action on the MVEB. The 
process for determining the adequacy of submitted SIP MVEBs is codified 
at 40 CFR 93.118.
2. What are safety margins?
    A ``safety margin'' is the difference between the attainment level 
of emissions from all sources and the projected level of emissions from 
all sources in the maintenance plan. As shown in Table 3, 
NOX emissions in the Dayton area are projected to have 
safety margins of 13,343 tpy and 21,262 tpy in 2015 and 2022, 
respectively (the difference between the attainment year, 2008, 
emissions and the projected 2015 and 2022 emissions for all sources in 
the Dayton area). Table 2 shows direct PM2.5 emissions in 
the Dayton area are projected to have a safety margin of 4479 tpy and 
712 tpy in 2015 and 2022, respectively. While, SO2 emissions 
as shown on Table 4 are projected to decrease and produce safety 
margins of 27 tpy in 2015 and 301 tpy in 2022. Even if emissions 
reached the full level of the safety margin, the area would still 
demonstrate maintenance since emission levels would equal those in the 
attainment year.
    The transportation conformity rule allows areas to allocate all or 
a portion of a ``safety margin'' to the area's motor vehicle emissions 
budgets (40 CFR 92.124(a)).
3. What are the MVEBs for the Dayton area?
    The maintenance plan revision submitted by Ohio for the Dayton area 
contains primary PM2.5 and NOX MVEBs for the area 
for the years 2015 and 2022.
    Ohio developed estimates for onroad mobile sources for the three 
counties in the Dayton area for 2005, 2008, 2015, and 2022. Ohio then 
summed the emissions for the Dayton area as shown on Table 6.

                           Table 6--Onroad Mobile Source Emissions for the Dayton Area
                                                      [tpy]
----------------------------------------------------------------------------------------------------------------
                                                       2005            2008            2015            2022
----------------------------------------------------------------------------------------------------------------
PM2.5...........................................          871.08          724.75          351.68          227.24
NOX.............................................       28,056.27       22,653.69       11,187.43        5,452.73
SO2.............................................          423.66          131.47           54.96           54.13
----------------------------------------------------------------------------------------------------------------

    The transportation conformity rule allows areas to allocate all or 
a portion of a ``safety margin'' to the area's motor vehicle emissions 
budgets (40 CFR 93.124(a)). Ohio is not requesting allocation to the 
MVEBs of the entire available safety margins reflected in the 
demonstration of maintenance. Therefore, even though the State has 
submitted MVEBs that exceed the projected onroad mobile source 
emissions for 2015 and 2022 contained in the demonstration of 
maintenance, the increase in onroad mobile source emissions that can be 
considered for transportation conformity purposes is well within the 
safety margins of the PM2.5 maintenance demonstration. 
Further, once allocated to mobile sources, these safety margins will 
not be available for use by other sources.
    Ohio did not provide emission budgets for SO2, VOCs, and 
ammonia because it concluded, consistent with the presumptions 
regarding these precursors in the conformity rule at 40 CFR 
93.102(b)(2)(v), which predated and was not disturbed by the litigation 
on the PM2.5 implementation rule, that emissions of these 
precursors from motor vehicles are not significant contributors to the 
area's PM2.5 air quality problem.
    EPA issued conformity regulations to implement the 1997 
PM2.5 NAAQS in July 2004 and May 2005 (69 FR 40004, July 1, 
2004 and 70 FR 24280, May 6, 2005, respectively). Those actions were 
not part of the final rule recently remanded to EPA by the Court of 
Appeals for the District of Columbia in NRDC v. EPA, No. 08-1250 (Jan. 
4, 2013), in which the Court remanded to EPA the implementation rule 
for the PM2.5 NAAQS because it concluded that EPA must 
implement that NAAQS pursuant to the PM-specific implementation 
provisions of subpart 4 of part D of title I of the CAA, rather than 
solely under the general provisions of subpart 1. That decision does 
not affect EPA's proposed approval of the Dayton MVEBs.
    First, as noted above, EPA's conformity rule implementing the 1997 
PM2.5 NAAQS was a separate action from the overall 
PM2.5 implementation rule addressed by the Court and was not 
considered or disturbed by the decision. Therefore, the conformity 
regulations were not at issue in NRDC v. EPA.\14\ In addition, as 
discussed in section III.B., the Dayton area is attaining the 1997 
annual standard for PM2.5 with a 2009-2011 design value of 
12.9 [micro]g/m\3\, which

[[Page 45151]]

is well below the annual PM2.5 NAAQS of 15 [micro]g/m\3\. 
The modeling analysis conducted for the RIA for the 2012 PM NAAQS 
indicates that the design value for this area is expected to continue 
to decline through 2020. Further, Ohio's maintenance plan shows 
continued maintenance through 2022 by demonstrating that 
NOX, SO2, and direct PM2.5 emissions 
continue to decrease through the maintenance period. For VOC and 
ammonia, RIA inventories for 2007 and 2020 show that both onroad and 
total emissions for these pollutants are expected to decrease, 
supporting the State's conclusion, consistent with the presumptions 
regarding these precursors in the conformity rule, that emissions of 
these precursors from motor vehicles are not significant contributors 
to the area's PM2.5 air quality problem and the MVEBs for 
these precursors are unnecessary. The onroad VOC emissions are expected 
to go from 11,156 to 4,598 tpy and ammonia emissions are projected to 
decline from 430 to 240 tpy. With regard to SO2, the 2005 
final conformity rule (70 FR 24280) based its presumption concerning 
onroad SO2 motor vehicle emissions budgets on emissions 
inventories that show that SO2 emissions from onroad sources 
constitute a ``de minimis'' portion of total SO2 emissions. 
As the emissions data on Tables 4 and 6 show, onroad emissions in 2022 
are less than 0.6 percent of total SO2 emissions in the 
area.
---------------------------------------------------------------------------

    \14\ The 2004 rulemaking addressed most of the transportation 
conformity requirements that apply in PM2.5 nonattainment 
and maintenance areas. The 2005 conformity rule included provisions 
addressing treatment of PM2.5 precursors in MVEBs. See 40 
CFR 93.102(b)(2). While none of these provisions were challenged in 
the NRDC case, EPA also notes that the Court declined to address 
challenges to EPA's presumptions regarding PM2.5 
precursors in the PM2.5 implementation rule. NRDC v. EPA, 
at 27, n. 10.
---------------------------------------------------------------------------

    The availability of the SIP submissions with these 2015 and 2022 
MVEBs was announced for public comment on EPA's Adequacy Web site on 
October 6, 2011, for the 1997 annual PM2.5 standard at: 
http://www.epa.gov/otaq/stateresources/transconf/currsips.htm. The EPA 
public comment periods on adequacy of the 2015 and 2022 MVEBs for the 
Dayton area closed on November 7, 2011. No adverse comments on the 
submission were received during the adequacy comment period.
    EPA has reviewed the submitted budgets for 2015 and 2022, including 
the added safety margins using the conformity rule's adequacy criteria 
found at 40 CFR 93.118(e)(4) and the conformity rule's requirements for 
safety margins found at 40 CFR 93.124(a). EPA has determined that the 
area can maintain attainment of the 1997 annual PM2.5 NAAQS 
for the relevant maintenance period with onroad mobile source emissions 
at the levels of the MVEBs since total emissions will still remain 
under attainment year emission levels. EPA is therefore proposing to 
approve the MVEBs submitted by Ohio for use in determining 
transportation conformity in the Dayton area.

V. Summary of Proposed Actions

    EPA is proposing to determine that the Dayton area is attaining the 
1997 annual PM2.5 NAAQS and that the area has met the 
requirements for redesignation under section 107(d)(3)(E) of the CAA. 
EPA is thus proposing to approve the requests from Ohio EPA to change 
the legal designations of the Dayton area from nonattainment to 
attainment for the 1997 annual PM2.5 standard. EPA is 
proposing to approve Ohio's PM2.5 maintenance plan for the 
Dayton area as a revision to the Ohio SIP because the plan meets the 
requirements of section 175A of the CAA. EPA is proposing to approve 
the 2005 and 2008 NOX, direct PM2.5, 
SO2 emission inventories along with the 2007/2008 ammonia 
and VOC emissions inventories as meeting the comprehensive emissions 
inventory requirements of section 172(c)(3) of the CAA. EPA is also 
proposing to find adequate and approve the MOVES-based NOX 
and direct PM2.5 2015 and 2022 MVEBs for the Dayton area for 
transportation conformity purposes. These MVEBs will be used in future 
transportation conformity analyses for the area.

VI. Statutory and Executive Order Reviews

    Under the CAA, redesignation of an area to attainment and the 
accompanying approval of a maintenance plan under section 107(d)(3)(E) 
are actions that affect the status of a geographical area and do not 
impose any additional regulatory requirements on sources beyond those 
imposed by state law. A redesignation to attainment does not in and of 
itself create any new requirements, but rather results in the 
applicability of requirements contained in the CAA for areas that have 
been redesignated to attainment. Moreover, the Administrator is 
required to approve a SIP submission that complies with the provisions 
of the CAA and applicable Federal regulations. 42 U.S.C. 7410(k); 40 
CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to 
approve state choices, provided that they meet the criteria of the CAA. 
Accordingly, these proposed actions do not impose additional 
requirements beyond those imposed by state law and the CAA. For that 
reason, these proposed actions:
     Are not ``significant regulatory actions'' subject to 
review by the Office of Management and Budget under Executive Order 
12866 (58 FR 51735, October 4, 1993);
     do not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     are certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     do not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     do not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     are not economically significant regulatory actions based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     are not significant regulatory actions subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     are not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     do not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, this proposed rule does not have tribal implications 
as specified by Executive Order 13175 (65 FR 67249, November 9, 2000), 
because a determination of attainment is an action that affects the 
status of a geographical area and does not impose any new regulatory 
requirements on tribes, impact any existing sources of air pollution on 
tribal lands, nor impair the maintenance of ozone national ambient air 
quality standards in tribal lands.

List of Subjects

40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Particulate matter.

40 CFR Part 81

    Environmental protection, Air pollution control, National parks, 
Wilderness areas.

[[Page 45152]]

    Dated: July 12, 2013.
Susan Hedman,
Regional Administrator, Region 5.
[FR Doc. 2013-18026 Filed 7-25-13; 8:45 am]
BILLING CODE 6560-50-P
```