The EPA Region 9 Regional Administrator, Jared Blumenfeld, signed the following proposed rule on 07/20/2012, and EPA is 

submitting it for publication in the Federal Register (FR). While we have taken steps to ensure the accuracy of this Internet 

version of the rule, it is not the official version of the rule for purposes of public comment. Please refer to the official version in a 

forthcoming FR publication, which will appear on the Government Printing Office's FDsys website 

(http://fdsys.gpo.gov/fdsys/search/home.action) and on Regulations.gov (http://www.regulations.gov) in Docket No. EPA-R09-

OAR-2012-0398. Once the official version of this document is published in the FR, this version will be removed from the 

Internet and replaced with a link to the official version.

1

Billing Code: 6560-50-P

ENVIRONMENTAL PROTECTION AGENCY

40 CFR part 52

[EPA-R09-OAR-2012-0398; FRL-_________]

Approval of Air Quality Implementation Plans; Arizona; 

Interstate Transport of Fine Particulate Matter

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

SUMMARY: EPA is proposing to approve a State Implementation Plan 

(SIP) revision submitted by the State of Arizona on October 14, 

2009 and to determine that the existing SIP is adequate to 

address the requirements of section 110(a)(2)(D)(i)(I) of the 

Clean Air Act (CAA) for the 2006 National Ambient Air Quality 

Standard (NAAQS or standard) for fine particulate matter (PM2.5). 

Section 110(a)(2)(D)(i)(I) of the CAA requires that each SIP 

contain adequate provisions to prohibit air emissions from 

adversely affecting air quality in other states through 

interstate transport. EPA is proposing to approve the SIP 

revision submitted by Arizona and to conclude that additional 

control measures in Arizona are not necessary under CAA section 
This document is a prepublication version, signed by EPA Region 9 Regional Administrator Jared Blumenfeld on 07/20/2012. 

We have taken steps to ensure the accuracy of this version, but it is not the official version.

2

110(a)(2)(D)(i)(I) because emissions from Arizona sources do not 

contribute significantly to nonattainment or interfere with 

maintenance of the 2006 24-hour PM2.5 NAAQS in any other state.

We are taking comments on this proposal and plan to follow with 

a final action.

DATES: Written comments must be received on or before [Insert 

date 30 days after publication in the Federal Register]. 

ADDRESSES: Submit your comments, identified by Docket ID Number 

EPA-R09-OAR-2012-0398, by one of the following methods:

1. http://www.regulations.gov: Follow the on-line instructions 

for submitting comments.

2. E-mail: vagenas.ginger@epa.gov

3. Fax: 415-942-3964

4. Mail or deliver: Ginger Vagenas (AIR-2), U.S. Environmental 

Protection Agency, Region IX, 75 Hawthorne Street, San 

Francisco, CA 94105-3901. Deliveries are only accepted 

during the Regional Office’s normal hours of operation.

Instructions: All comments will be included in the public 

docket without change and may be made available online at 

http://www.regulations.gov, including any personal information

provided, unless the comment includes Confidential Business 

Information (CBI) or other information whose disclosure is

restricted by statute. Information that you consider CBI or 

otherwise protected should be clearly identified as such and 
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We have taken steps to ensure the accuracy of this version, but it is not the official version.

3

should not be submitted through http://www.regulations.gov or email. http://www.regulations.gov is an anonymous access system, 

and EPA will not know your identity or contact information 

unless you provide it in the body of your comment. If you send 

email directly to EPA, your e-mail address will be automatically 

captured and included as part of the public comment. 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.

Docket: Generally, documents in the docket for this action 

are available electronically at www.regulations.gov and in hard 

copy at EPA Region IX, 75 Hawthorne Street, San Francisco, 

California. While all documents in the docket are listed at 

www.regulations.gov, some information may be publicly available 

only at the hard copy location (e.g., copyrighted material, 

large maps), and some may not be publicly available in either 

location (e.g., CBI). To inspect the hard copy materials, 

please schedule an appointment during normal business hours with 

the contact listed in the FOR FURTHER INFORMATION CONTACT

section.

FOR FURTHER INFORMATION CONTACT: Ginger Vagenas, Air Planning 

Office (AIR–2), U.S. Environmental Protection Agency, Region IX, 

(415)972-3964 vagenas.ginger@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document, the terms
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4

“we,” “us,” and “our” refer to EPA.

TABLE OF CONTENTS

I. Background

II. The State’s Submittal

III. EPA’s Evaluation

IV. Proposed Action

V. Statutory and Executive Order Reviews

I. Background

A. 2006 24-hour PM2.5 NAAQS Infrastructure Requirements

On September 21, 2006, EPA promulgated a final rule 

revising the 1997 24-hour primary and secondary NAAQS for PM2.5

from 65 micrograms per cubic meter (μg/m3) to 35 μg/m3. 71 FR 

61144 (October 17, 2006).

Section 110(a)(1) of the CAA requires each state to submit 

to EPA, within 3 years (or such shorter period as the 

Administrator may prescribe) after the promulgation of a primary 

or secondary NAAQS or any revision thereof, a SIP that provides 

for the “implementation, maintenance, and enforcement” of such 

NAAQS. EPA refers to these specific submissions as 

“infrastructure” SIPs because they are intended to address basic 

structural SIP requirements for new or revised NAAQS. For the 

2006 24-hour PM2.5 NAAQS, these infrastructure SIPs were due on
This document is a prepublication version, signed by EPA Region 9 Regional Administrator Jared Blumenfeld on 07/20/2012. 

We have taken steps to ensure the accuracy of this version, but it is not the official version.

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September 21, 2009.

1 Section 110(a)(2) includes a list of 

specific elements that each such plan submission must meet, 

including section 110(a)(2)(D)(i), which pertains to interstate 

transport of certain emissions.

The transport SIP provisions in section 110(a)(2)(D)(i) 

(also called "good neighbor" provisions) require each state to 

submit a SIP that prohibits emissions that adversely affect 

another state in the ways contemplated in the statute. Section 

110(a)(2)(D)(i) identifies four distinct elements related to the 

evaluation of impacts of interstate transport of air pollutants. 

In this action, EPA is addressing the first two elements of this 

section (i.e., the requirements in section 110(a)(2)(D)(i)(I) to 

prohibit emissions activity within a state that will 

significantly contribute to nonattainment or interfere with 

maintenance of the NAAQS in any other state) for the 2006 24-

hour PM2.5 NAAQS.

2

 

1 The rule establishing the revised PM2.5 NAAQS was signed by the Administrator 

and publically disseminated on September 21, 2006. Because EPA did not 

prescribe a shorter period for section 110(a) “infrastructure” SIP submittals

for these NAAQS, these submittals were due on September 21, 2009, three years 

from the September 21, 2006 signature date pursuant to section 110(a)(1) of 

the CAA. See 42 U.S.C. 7410(a)(1). 

2 This proposed action does not address the remaining two elements of the 

transport SIP provision (in CAA section 110(a)(2)(D)(i)(II)) regarding 

interference with measures required to prevent significant deterioration of 

air quality or to protect visibility in another state. We intend to evaluate 

and act upon Arizona’s SIP submissions addressing these additional 

requirements of CAA section 110(a)(2)(D)(i) in separate rulemakings. We 

proposed action on Arizona’s provisions regarding interference with other 

states' measures to prevent significant deterioration of air quality on June 

27, 2012. See 77 FR 38239.
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The first element of section 110(a)(2)(D)(i) requires that 

each SIP for a new or revised NAAQS contain adequate measures to 

prohibit any source or other type of emissions activity within 

the state from emitting air pollutants that will “contribute

significantly to nonattainment” of the NAAQS in another state. 

The second element of CAA section 110(a)(2)(D)(i) requires that 

each SIP prohibit any source or other type of emissions activity 

in the state from emitting pollutants that will "interfere with 

maintenance" of the applicable NAAQS in any other state.

B. NOX SIP call, Clean Air Interstate Rule (CAIR) and the 

Transport Rule 

EPA has previously addressed the requirements of section 

110(a)(2)(D)(i)(I) in past regulatory actions such as the 1998 

NOx SIP call,

3 the 2005 Clean Air Interstate Rule (“CAIR”),4 and 

the 2011 Transport Rule (also known as the “Cross-State Air 

Pollution Rule” or “CSAPR”).5 In the NOx SIP call, EPA took 

action to remediate emissions of nitrogen oxides (NOx) that 

significantly contributed to nonattainment of, or interfered 

with maintenance of, the then applicable ozone NAAQS through 

 

3 See “Finding of Significant Contribution and Rulemaking for Certain States 

in the Ozone Transport Assessment Group Region for Purposes of Reducing 

Regional Transport of Ozone,” 63 FR 57356(October 27, 1998)(“NOx SIP Call”).

4 See “Rule to Reduce Interstate Transport of Fine Particulate Matter and 

Ozone (Clean Air Interstate Rule); Revisions to Acid Rain Program; Revisions 

to the NOx SIP Call” 70 FR 25162 (May 12, 2005)(“CAIR”).

5 See “Federal Implementation Plans: Interstate Transport of Fine Particulate 

Matter and Ozone and Correction of SIP Approvals; Final Rule” 76 FR 48208

(August 8, 2011) (“Transport Rule”).
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interstate transport of NOx and the resulting ozone.6 Through 

this rule, EPA evaluated whether or not the ozone-season NOx

emissions in certain states had prohibited interstate impacts, 

and if they had such impacts, required the states to adopt 

substantive SIP revisions to eliminate the NOx emissions, whether 

through participation in a regional cap and trade program or by 

other means.7

After promulgation of the 1997 8-hour ozone NAAQS and the 

1997 PM2.5 NAAQS, EPA again recognized that regional transport 

was a serious concern throughout the eastern United States and 

therefore developed CAIR to address emissions of sulfur dioxide 

(SO2) and NOx that exacerbate ambient ozone and PM2.5 levels in 

many downwind areas through interstate transport.8 Within CAIR, 

EPA interpreted the term "interfere with maintenance" as part of 

the evaluation of whether or not the emissions of sources in 

certain states had such impacts on areas that EPA projected

would be in violation of the NAAQS unless actions were taken by 

upwind states to reduce SO2 and NOx emissions. Through CAIR, EPA 

again required states that had such interstate impacts to adopt 

substantive SIP revisions to eliminate the SO2 and NOx emissions, 

 

6 See 63 FR 57356 (October 27, 1998). EPA's general approach to section 

110(a)(2)(D) in the NOx SIP Call was upheld in Michigan v. EPA, 213 F.3d 663

(D.C. Cir. 2000), cert denied, 532 U.S. 904 (2001). However, EPA's approach 

to interference with maintenance in the NOx SIP Call was not explicitly 

reviewed by the court. See North Carolina v. EPA, 531 F.3d 896, 907-09 (D.C. 

Cir. 2008).

7 Ibid.

8 See 70 FR 25162 at 25263-69 (May 12, 2005).
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whether through participation in a regional cap and trade 

program or by other means. 

In 2008, the U.S. Court of Appeals for the D.C. Circuit 

found that CAIR and the related CAIR federal implementation 

plans were unlawful. North Carolina v. EPA, 531 F.3d 896 (D.C. 

Cir. 2008), modified on rehearing, North Carolina v. EPA, 550 

F.3d 1176, 1178 (D.C. Cir. 2008). Among other issues, the court 

held that EPA had not correctly addressed the second element of 

section 110(a)(2)(D)(i)(I) in CAIR and noted that "EPA gave no 

independent significance to the ‘interfere with maintenance’

prong of section 110(a)(2)(D)(i)(I) to separately identify 

upwind sources interfering with downwind maintenance." 531 F.3d 

at 909. EPA's approach, the court reasoned, would leave areas 

that are "barely meeting attainment" with "no recourse" to 

address upwind emissions sources. Id. The court therefore 

concluded that a plain language reading of the statute requires 

EPA to give independent meaning to the interfere with 

maintenance requirement of section 110(a)(2)(D)(i) and that the 

approach used by EPA in CAIR failed to do so.

To address the judicial remand of CAIR and to replace it,

on August 8, 2011, EPA published the final Transport Rule. 76 FR 

48208. The Transport Rule addresses interstate transport 

pursuant to CAA section 110(a)(2)(D)(i)(I) in the eastern United 

States with respect to the 1997 8-hour ozone NAAQS, the 1997 
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9

PM2.5 NAAQS, and the 2006 24-hour PM2.5 NAAQS.9 As part of this 

rulemaking, EPA specifically reexamined the section 

110(a)(2)(D)(i)(I) requirements to prohibit emissions from 

sources in a state that “contribute significantly to 

nonattainment” or “interfere with maintenance” of the NAAQS in 

other states and developed an approach to identify (1) areas 

that it predicts to be violating the NAAQS, and (2) areas that 

it predicts to be close to the level of these NAAQS and 

therefore at risk to become nonattainment unless emissions from 

sources in other states are appropriately controlled. This 

approach starts by identifying those specific geographic areas 

for which further evaluation is appropriate and differentiates 

between areas where the concern is significant contribution to 

nonattainment as opposed to interference with maintenance. EPA 

then conducts state-specific analyses of multiple factors 

related to pollution levels at the identified “receptors” 

(monitoring sites) of concern to evaluate significant 

contribution to nonattainment and interference with maintenance 

of the NAAQS in other states. 

On December 30, 2011, the U.S. Court of Appeals for the 

D.C. Circuit issued an order addressing the status of the 

Transport Rule and CAIR in response to motions filed by numerous 

parties seeking a stay of the Transport Rule pending judicial 

 

9 CAIR did not address the 2006 24-hour PM2.5 NAAQS.
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review.10 In that order, the court stayed the Transport Rule 

pending resolution of these petitions for review of the rule.

The court also stated that EPA is expected to continue to 

administer CAIR in the interim until the court rules on these

petitions for review of the Transport Rule.

C. EPA Guidance

On September 25, 2009, after the court remanded CAIR and 

while EPA was working on its replacement, EPA issued a guidance 

memorandum that provides recommendations to states for making 

submissions to meet the requirements of CAA section 

110(a)(2)(D)(i) for the 2006 PM2.5 standards (“2006 PM2.5 NAAQS 

Infrastructure Guidance” or “Guidance”).

11 With respect to the 

requirement in section 110(a)(2)(D)(i)(I) to prohibit emissions 

that would contribute significantly to nonattainment of the 

NAAQS in any other state, the 2006 PM2.5 NAAQS Infrastructure 

Guidance essentially reiterated the recommendations for western 

states made by EPA in previous guidance addressing the 

110(a)(2)(D)(i) requirements for the 1997 8-hour Ozone and 1997

PM2.5 NAAQS.12 The 2006 PM2.5 NAAQS Infrastructure Guidance advised 

 

10 See Order dated December 30, 2011, EME Homer City Generation, L.P. v. EPA

(No. 11-1302 and consolidated cases) (D.C. Circuit).

11 See Memorandum from William T. Harnett entitled “Guidance on SIP Elements 

Required Under Sections 110(a)(1) and (2) for the 2006 24-Hour Fine Particle 

(PM2.5) National Ambient Air Quality Standards (NAAQS),” September 25, 2009.

12 See Memorandum from William T. Harnett entitled “Guidance for State 

Implementation Plan (SIP) Submission to Meet Current Outstanding Obligations 
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states outside of the CAIR region to include in their section 

110(a)(2)(D)(i)(I) SIPs adequate technical analyses to support 

their conclusions regarding interstate pollution transport, 

e.g., information concerning emissions in the state, 

meteorological conditions in the state and in potentially 

impacted states, monitored ambient pollutant concentrations in 

the state and in potentially impacted states, distances to the 

nearest areas not attaining the NAAQS in other states, and air 

quality modeling. See 2006 PM2.5 NAAQS Infrastructure Guidance at 

3.13 With respect to the requirement in section 

110(a)(2)(D)(i)(I) to prohibit emissions that would interfere 

with maintenance of the NAAQS by any other state, the Guidance 

stated that SIP submissions must address this independent 

requirement of the statute and provide technical information 

appropriate to support the state’s conclusions, such as 

information concerning emissions in the state, meteorological

conditions in the state and in potentially impacted states, 

monitored ambient concentrations in the state and in potentially 

 

Under Section 110(a)(2)(D)(i) for the 8-hour ozone and PM2.5 National Ambient 

Air Quality Standards,” August 15, 2006.

13 The 2006 PM2.5 NAAQS Infrastructure Guidance stated that EPA was working on 

a new rule to replace CAIR that would address issues raised by the court in 

the North Carolina case and that would provide guidance to states in 

addressing the requirements related to interstate transport in CAA section 

110(a)(2)(D)(i)(I) for the 2006 PM2.5 NAAQS. It also noted that states could 

not rely on the CAIR rule for section 110(a)(2)(D)(i)(I) submissions for the

2006 24-hour PM2.5 NAAQS because the CAIR rule did not address this NAAQS. See

2006 PM2.5 NAAQS Infrastructure Guidance at 3.
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impacted states, and air quality modeling. See 2006 PM2.5 NAAQS 

Infrastructure Guidance at 3, 4.

In this action, EPA is maintaining the conceptual approach 

to evaluating interstate pollution transport under CAA section 

110(a)(2)(D)(i)(I) that the Agency provided in the 2006 PM2.5

NAAQS Infrastructure Guidance and the Transport Rule.

As described more fully in our Technical Support Document 

(TSD), EPA evaluated data from existing monitors over three 

overlapping 3-year periods (i.e., 2006-2008, 2007–2009, and 

2008-2010) to determine which areas are expected to be violating 

the 2006 24-hour PM2.5 NAAQS and which areas are predicted to 

potentially have difficulty maintaining attainment. In essence, 

if a monitoring site shows a violation of the 2006 24-hour PM2.5

NAAQS during the most recent 3-year period (2008-2010), then 

this monitor location is appropriate for evaluation for purposes 

of the significant contribution to nonattainment element of 

section 110(a)(2)(D)(i)(I). If, on the other hand, a monitoring 

site shows attainment of the 2006 24-hour PM2.5 NAAQS during the 

most recent 3-year period (2008-2010) but a violation in at 

least one of the previous two 3-year periods (2006-2008 or 2007–

2009), then this monitor location is appropriate for evaluation

for purposes of the interfere with maintenance element of the 

statute. 
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By this method, EPA has identified those areas with 

monitors that are appropriate “nonattainment receptors” or 

“maintenance receptors” for evaluating whether the emissions 

from sources in another state could significantly contribute to 

nonattainment in, or interfere with maintenance in, that 

particular area. EPA believes that this approach for identifying 

areas that are predicted to be nonattainment and significantly 

impacted by other states, or have difficulty maintaining the 

NAAQS, is appropriate to evaluate a state’s submission in 

relation to the elements of CAA section 110(a)(2)(D)(i)(I)

pertaining to significant contribution to nonattainment and 

interference with maintenance.

EPA continues to believe that the more widespread and 

serious transport problems in the eastern United States are 

analytically distinct.14 For the 2006 PM2.5 NAAQS, EPA believes 

that nonattainment and maintenance problems in the western 

United States are relatively local in nature with only limited 

impacts from interstate transport. In the Transport Rule, EPA 

did not calculate the portion of any downwind state’s predicted

PM2.5 concentrations that would result from emissions from 

individual western states, such as Arizona. Accordingly, EPA 

believes that section 110(a)(2)(D)(i)(I) SIP submissions for 

states outside the geographic area analyzed to develop the 

 

14 See Transport Rule Proposal, 75 FR 45210 at 45227 (August 2, 2010).
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Transport Rule may be evaluated using a “weight of the evidence” 

approach that takes into account available relevant information, 

such as that recommended by EPA in the 2006 PM2.5 NAAQS 

Infrastructure Guidance. Such information may include, but is 

not limited to, the amount of emissions in the state relevant to 

the NAAQS in question, the meteorological conditions in the 

area, the distance from the state to the nearest monitors in 

other states that are appropriate receptors, or such other 

information as may be probative to consider whether sources in 

the state may contribute significantly to nonattainment or 

interfere with maintenance of the 2006 24-hour PM2.5 NAAQS in 

other states. These submissions can rely on modeling when 

acceptable modeling technical analyses are available, but EPA 

does not believe that modeling is necessarily required if other 

available information is sufficient to evaluate the presence or 

degree of interstate transport in a given situation.

II. The State’s Submittal

CAA sections 110(a) and 110(l) require that revisions to a 

SIP be adopted by the State after reasonable notice and public 

hearing. EPA has promulgated specific procedural requirements 

for SIP revisions in 40 CFR part 51, subpart F. These 

requirements include publication of notices, by prominent 

advertisement in the relevant geographic area, of a public 
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hearing on the proposed revisions, a public comment period of at 

least 30 days, and an opportunity for a public hearing.

On October 14, 2009, the Arizona Department of 

Environmental Quality (ADEQ) submitted the “Arizona State 

Implementation Plan Revision under Clean Air Act Section 

110(a)(1) and (2); 2006 PM2.5 NAAQS, 1997 PM2.5 NAAQS and 1997 8-

hour Ozone NAAQS,” to address the requirements of CAA section 

110(a)(2)(D)(i)(I) for the 2006 PM2.5 NAAQS, among other 

requirements (“2009 Infrastructure Analysis”).

15 Within that 

submittal, Appendix B, “Clean Air Act Section 110(a)(2)(D)(i) –

Interstate Transport Analysis for the 2006 PM2.5 National Ambient 

Air Quality Standards” (referred to herein as “PM2.5 Transport 

Analysis”) addresses the CAA section 110(a)(2)(D)(i)(I) 

interstate transport requirements that are the subject of this 

proposed rule. 

ADEQ’s October 14, 2009 submittal includes public process 

documentation for the 2009 Infrastructure Analysis, including 

the PM2.5 Transport Analysis. In addition, the SIP revision 

includes documentation of a duly noticed public hearing held on 

 

15 ADEQ intended for this SIP submittal to also address all other requirements 

of CAA section 110(a), excepting section 110(a)(2)(G), for the 1997 8-hour 

ozone and PM2.5 NAAQS and the 2006 PM2.5 NAAQS. See letter dated October 14, 

2009, from Eric C. Massey, Air Quality Director, ADEQ, to Laura Yoshii, 

Acting Regional Administrator, EPA Region 9, with enclosures. EPA has 

proposed to act on this submittal for purposes of addressing the other 

“infrastructure” requirements of CAA section 110(a) in a separate proposed 

rule published on June 27, 2012 (77 FR 38239).
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September 16, 2009, on the proposed 2009 Infrastructure 

Analysis.

We find that the process followed by ADEQ in adopting the 

PM2.5 Transport Analysis complies with the procedural 

requirements for SIP revisions under CAA section 110 and EPA’s 

implementing regulations.

III. EPA’s Evaluation 

To determine whether the CAA section 110(a)(2)(D)(i)(I) 

requirement is satisfied, EPA must determine whether a state’s 

emissions contribute significantly to nonattainment or interfere 

with maintenance in downwind areas. If this factual finding is 

in the negative, then section 110(a)(2)(D)(i)(I) does not 

require any changes to a state’s SIP. If, however, the 

evaluation reveals that emissions from sources within the state 

do contribute significantly to nonattainment or interfere with 

maintenance in other states, then the state must adopt 

substantive provisions to eliminate those emissions. The state 

could achieve any required reductions through traditional 

command and control programs, or at its own election, through 

participation in a cap and trade program. Consistent with EPA's 

approach in the 1998 NOx SIP call, the 2005 CAIR, and the 2011 

Transport Rule,16 EPA is evaluating these impacts with respect to 

 

16 See NOx SIP Call, 63 FR 57371 (October 27, 1998); CAIR, 70 FR 25172 (May 12, 

2005); and Transport Rule or Cross-State Air Pollution Rule, 76 FR 48208 

(August 8, 2011).
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specific monitors identified as having nonattainment and/or 

maintenance problems, which we refer to as “receptors.” EPA 

notes that no single piece of information is by itself 

dispositive of the issue. Instead, the total weight of all the 

evidence taken together is used to evaluate significant 

contributions to nonattainment or interference with maintenance 

of the 2006 24-hour PM2.5 NAAQS in another state.

This proposed approval addresses the requirements of CAA 

section 110(a)(2)(D)(i)(I) for the 2006 24-hour PM2.5 NAAQS in 

several ways. It takes into account Arizona’s PM2.5 Transport 

Analysis, which explains that meteorological and other 

characteristics in Arizona and in the surrounding areas reduce 

the likelihood that Arizona’s emissions contribute significantly 

to nonattainment or interfere with maintenance of the 2006 24-

hour PM2.5 NAAQS in any downwind state. In addition, EPA has 

supplemented its evaluation of Arizona’s submittal with a review 

of the monitors in other states that are appropriate 

“nonattainment receptors” or “maintenance receptors,” consistent 

with EPA’s approach in the Transport Rule, and additional 

technical information to consider whether sources in Arizona

contribute significantly to nonattainment or interfere with 

maintenance of the 2006 24-hour PM2.5 NAAQS in other states.

Our Technical Support Document (TSD) contains a more 

detailed evaluation and is available in the public docket for 
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this rulemaking, which may be accessed online at 

http://www.regulations.gov, docket number EPA-R09-OAR-2012-0398.

We provide below a summary of our analysis.

A. Evaluation of Significant Contribution to Nonattainment

EPA reviewed the State of Arizona’s PM2.5 Transport Analysis 

and additional technical information to evaluate the potential 

for Arizona emissions to contribute significantly to 

nonattainment of the 2006 PM2.5 NAAQS at specified monitoring 

sites in the western United States.17 EPA first identified as 

“nonattainment receptors” all monitoring sites in the western 

states that had recorded PM2.5 design values above the level of 

the 2006 24-hour PM2.5 NAAQS (35 g/m3) during the years 2008-

2010.18 See Section III of the TSD for more a more detailed 

description of EPA’s methodology for selection of nonattainment 

receptors. Because geographic distance is a relevant factor in 

 

17 EPA has also considered potential PM2.5 transport from Arizona to the 

nearest nonattainment and maintenance receptors located in the eastern, 

midwestern and southern states covered by the Transport Rule and believes it 

is reasonable to conclude that, given the significant distance from Arizona 

to the nearest such receptor (in Illinois) and the relatively insignificant 

amount of emissions from Arizona that could potentially be transported such a 

distance, emissions from Arizona sources do not significantly contribute to 

nonattainment or interfere with maintenance of the 2006 24-hour PM2.5 NAAQS at 

this location. These same factors also support a finding that emissions from 

Arizona sources neither contribute significantly to nonattainment nor 

interfere with maintenance of the 2006 24-hour PM2.5 NAAQS at any location

further east. See TSD at Section I.B.3.

18 Because CAIR did not cover states in the western United States, these data 

are not significantly impacted by the remanded CAIR and thus could be 

considered in this analysis. In contrast, recent air quality data in the 

eastern, midwestern and southern states are significantly impacted by 

reductions associated with CAIR and because the Transport Rule was developed 

to replace CAIR, EPA could not consider reductions associated with the CAIR 

in the base case transport analysis for those states. See 76 FR at 48223-24.
This document is a prepublication version, signed by EPA Region 9 Regional Administrator Jared Blumenfeld on 07/20/2012. 

We have taken steps to ensure the accuracy of this version, but it is not the official version.

19

the assessment of potential pollution transport, EPA focused its 

review on information related to potential transport of PM2.5

pollution from Arizona to nonattainment receptors in the states 

bordering Arizona: Utah, Nevada, and California.19 With respect 

to Utah and Nevada, as detailed in the TSD, EPA believes that 

the following factors support a finding that emissions from 

Arizona do not significantly contribute to nonattainment of the 

2006 24-hour PM2.5 NAAQS in either of these states: (1) technical 

information indicating that elevated PM2.5 levels at 

nonattainment receptors are predominantly caused by local 

emission sources, (2) air quality data indicating that regional 

background levels of PM2.5 are generally low during the time 

periods of elevated PM2.5 at these receptors, and (3) the 

presence of significant terrain, which creates a physical 

impediment to pollution transport. Similarly and again as 

detailed in the TSD, with respect to California, technical 

information indicating that elevated PM2.5 levels at the 

nonattainment receptors are predominantly caused by local 

emission sources and that the dominant air flows across 

California are from the west to the east support a finding that 

emissions from the state of Arizona do not significantly 

contribute to nonattainment of the 2006 24-hour PM2.5 standards 

in California.

 

19 EPA did not identify any nonattainment receptors in New Mexico or Colorado. 
This document is a prepublication version, signed by EPA Region 9 Regional Administrator Jared Blumenfeld on 07/20/2012. 

We have taken steps to ensure the accuracy of this version, but it is not the official version.

20

EPA also evaluated potential PM2.5 transport to 

nonattainment receptors in the more distant western states of 

Oregon, Washington, Idaho, and Montana.20 EPA believes that the 

following factors support a finding that emissions from Arizona 

do not significantly contribute to nonattainment of the 2006 24-

hour PM2.5 NAAQS in any of these states: (1) the significant 

distance from the State of Arizona to the nonattainment 

receptors in these states, (2) technical information indicating 

that elevated PM2.5 levels at nonattainment receptors in these 

states are predominantly caused by local emission sources, (3) 

air quality data indicating that regional background levels of 

PM2.5 are generally low during the time periods of elevated PM2.5

at these receptors, and (4) the presence of significant terrain, 

which creates a physical impediment to pollution transport.

Based on this evaluation of Arizona’s PM2.5 Transport 

Analysis and additional technical information, EPA proposes to 

conclude that emissions of direct PM2.5 and PM2.5 precursors from 

sources in the State of Arizona do not significantly contribute 

to nonattainment of the 2006 24-hour PM2.5 standards in any other

state and that CAA section 110(a)(2)(D)(i)(I) therefore does not 

require Arizona to adopt additional controls for purposes of 

implementing the 2006 24-hour PM2.5 standards.

B. Evaluation of Interference with Maintenance

 

20 EPA did not identify any nonattainment receptors in Wyoming. 
This document is a prepublication version, signed by EPA Region 9 Regional Administrator Jared Blumenfeld on 07/20/2012. 

We have taken steps to ensure the accuracy of this version, but it is not the official version.

21

EPA reviewed the State of Arizona’s PM2.5 Transport Analysis 

and additional technical information to evaluate the potential 

for Arizona emissions to interfere with maintenance of the 2006 

24-hour PM2.5 standards at specified monitoring sites in the 

western U.S. EPA first identified as “maintenance receptors” all 

monitoring sites in the western states that had recorded PM2.5

design values above the level of the 2006 24-hour PM2.5 NAAQS (35 

g/m3) during the 2006-2008 and/or 2007-2009 periods but below 

this standard during the 2008-2010 period. See section IV of the 

TSD for more information regarding EPA’s methodology for 

selection of maintenance receptors. All of the maintenance 

receptors in the western states are located in California, Utah,

and Arizona. EPA therefore evaluated the potential for transport 

of Arizona emissions to the maintenance receptors located in 

California and Utah.

21 As detailed in the TSD, EPA believes that 

the following factors support a finding that emissions from 

Arizona do not interfere with maintenance of the 2006 24-hour 

PM2.5 NAAQS in either state: (1) technical information indicating 

that elevated PM2.5 levels at these maintenance receptors are 

predominantly caused by local emission sources, and (2) 

technical information indicating that the dominant air flows 

across California are from the west to the east.

 

21 As this analysis focused on interstate transport, EPA did not evaluate the 

impact of Arizona emissions on maintenance receptors within Arizona. (EPA has 

not identified any nonattainment receptors in Arizona.)
This document is a prepublication version, signed by EPA Region 9 Regional Administrator Jared Blumenfeld on 07/20/2012. 

We have taken steps to ensure the accuracy of this version, but it is not the official version.

22

Based on this evaluation of Arizona’s PM2.5 Transport 

Analysis and additional technical information, EPA proposes to 

conclude that emissions of direct PM2.5 and PM2.5 precursors from 

sources in the State of Arizona do not interfere with 

maintenance of the 2006 24-hour PM2.5 standards in any other 

state and that CAA section 110(a)(2)(D)(i)(I) therefore does not 

require Arizona to adopt additional controls for purposes of 

implementing the 2006 24-hour PM2.5 standards.

C. Section 110(l) of the Act

Section 110(l) of the Act prohibits EPA from approving any 

SIP revision that would interfere with any applicable 

requirement concerning attainment and reasonable further 

progress (RFP) or any other applicable requirement of the Act. 

The PM2.5 Transport Analysis contains no regulatory provisions 

and does not affect any requirement in Arizona’s applicable 

implementation plan. We propose to determine that our approval 

of the PM2.5 Transport Analysis would comply with CAA section 

110(l) because the proposed SIP revision would not interfere 

with the on-going process for ensuring that requirements for RFP 

and attainment of the NAAQS are met. The SIP revision does not 

alter any provisions in the SIP as EPA has concluded, based on 

its supplemental analysis, that the existing SIP is sufficient 

to meet the requirements of 110(a)(2)(D)(i)(I). Our TSD contains 

a more detailed discussion of our evaluation.
This document is a prepublication version, signed by EPA Region 9 Regional Administrator Jared Blumenfeld on 07/20/2012. 

We have taken steps to ensure the accuracy of this version, but it is not the official version.

23

IV. Proposed Action

Under section 110(k) of the Clean Air Act, EPA is proposing

to approve a SIP revision submitted by the State of Arizona on

October 14, 2009 and to determine, based on that submission and 

additional EPA analysis, that emissions from Arizona sources do 

not contribute significantly to nonattainment of the 2006 24-

hour PM2.5 NAAQS in any other state or interfere with maintenance 

of the 2006 24-hour PM2.5 NAAQS by any other state. Accordingly, 

we propose to conclude that the existing SIP is adequate to 

address the requirements of section 110(a)(2)(D)(i)(I) of the 

Clean Air Act (CAA) for the 2006 National Ambient Air Quality 

Standard (NAAQS or standard) for fine particulate matter (PM2.5)

and that additional control measures in Arizona are not 

necessary for this purpose. 

EPA is soliciting public comments on this proposal and will 

accept comments until the date noted in the “DATES” section 

above.

IV. Statutory and Executive Order Reviews

Under the Clean Air Act, the Administrator is required to 

approve a SIP submission that complies with the provisions of 

the Act 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 Clean Air Act. Accordingly, this action merely 
This document is a prepublication version, signed by EPA Region 9 Regional Administrator Jared Blumenfeld on 07/20/2012. 

We have taken steps to ensure the accuracy of this version, but it is not the official version.

24

proposes to approve state law as meeting Federal requirements 

and does not impose additional requirements beyond those imposed 

by state law. For that reason, this proposed action:

• is not a "significant regulatory action" subject to review 

by the Office of Management and Budget under Executive 

Order 12866 (58 FR 51735, October 4, 1993);

• does not impose an information collection burden under the 

provisions of the Paperwork Reduction Act (44 U.S.C. 3501 

et seq.);

• is 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.);

• does not contain any unfunded mandate or significantly or 

uniquely affect small governments, as described in the 

Unfunded Mandates Reform Act of 1995 (Public Law 104-4);

• does not have Federalism implications as specified in 

Executive Order 13132 (64 FR 43255, August 10, 1999);

• is not an economically significant regulatory action based 

on health or safety risks subject to Executive Order 13045 

(62 FR 19885, April 23, 1997);

• is not a significant regulatory action subject to Executive 

Order 13211 (66 FR 28355, May 22, 2001);

• is not subject to requirements of Section 12(d) of the 

National Technology Transfer and Advancement Act of 1995 
This document is a prepublication version, signed by EPA Region 9 Regional Administrator Jared Blumenfeld on 07/20/2012. 

We have taken steps to ensure the accuracy of this version, but it is not the official version.

25

(15 U.S.C. 272 note) because application of those 

requirements would be inconsistent with the Clean Air Act; 

and

• does 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 the SIP is not approved to apply in 

Indian country located in the state, and EPA notes that it will 

not impose substantial direct costs on tribal governments or 

preempt tribal law.

List of Subjects in 40 CFR Part 52

Air pollution control, Environmental protection, 

Intergovernmental relations, Nitrogen dioxide, Ozone, Reporting 

and recordkeeping requirements, Volatile organic compounds. 

Authority: 42 U.S.C. 7401 et seq.

_________________ _____________________________________

Date Jared Blumenfeld,
This document is a prepublication version, signed by EPA Region 9 Regional Administrator Jared Blumenfeld on 07/20/2012. 

We have taken steps to ensure the accuracy of this version, but it is not the official version.

26

Regional Administrator,

Region IX