Technical Support Document - Sections 110(a)(2)(C), 110(a)(2)(D)(i)(II) (Prong 3) and 

110(a)(2)(J) related to Prevention of Significant Deterioration (PSD) for Mississippi

Section 110(a)(2)(C) has three components that must be addressed in infrastructure SIP 

submissions: enforcement, state-wide regulation of new and modified minor sources and minor 

modifications of major sources; and PSD permitting of major sources and major modifications in 

areas designated attainment or unclassifiable for the subject national ambient air quality standard 

(NAAQS) as required by CAA title I part C (i.e., the major source PSD program). 

Section 110(a)(2)(D)(i) has two components: 110(a)(2)(D)(i)(I) and 110(a)(2)(D)(i)(II). 

Each of these components have two subparts resulting in four distinct components, commonly 

referred to as “prongs,” that must be addressed in infrastructure SIP submissions. The first two 

prongs, which are codified in section 110(a)(2)(D)(i)(I), are provisions that prohibit any source 

or other type of emissions activity in one state from contributing significantly to nonattainment 

of the NAAQS in another state (“prong 1”), and interfering with maintenance of the NAAQS in 

another state (“prong 2”). The third and fourth prongs, which are codified in section 

110(a)(2)(D)(i)(II), are provisions that prohibit emissions activity in one state from interfering 

with measures required to prevent significant deterioration of air quality in another state (“prong 

3”), or to protect visibility in another state (“prong 4”).

Section 110(a)(2)(J) has four components that must be addressed in infrastructure SIP 

submissions: 1) consultation with government officials, 2) public notification, 3) prevention of 

significant deterioration, and 4) visibility protection. 
With respect to the PSD elements of 110(a)(2)(C) and (J), EPA interprets the CAA to 

require each state to make, for each new or revised NAAQS, an infrastructure SIP submission 

that demonstrates that the air agency has a complete PSD permitting program meeting the current 

requirements for all regulated new source review (NSR) pollutants. The requirements of element 

110(a)(2)(D)(i)(II) may also be satisfied by demonstrating the air agency has a complete PSD 

permitting program correctly addressing all regulated NSR pollutants.

The PSD Program Requirements for Infrastructure SIPs

In order for the PSD elements of infrastructure SIP submissions to be approvable, a 

state’s submission must demonstrate that all structural PSD program elements that are currently 

due under the CAA and EPA regulations are either approved into the SIP or are submitted for 

approval, in which case EPA must take final action to approve these elements before or 

simultaneously with its action on the infrastructure SIP. There are four more recent structural 

PSD program requirements that are relevant to EPA’s review of the PSD elements of the 

infrastructure SIP submissions. The EPA regulations that require these SIP revisions are: 1) the

Phase II Rule1; 2) the Greenhouse Gas (GHG) Tailoring Rule2 as consistent with the holding in 

Utility Air Regulatory Group v. Environmental Protection Agency;

3 3) the NSR Fine Particulate 

Matter (PM2.5) Rule4; and 4) the PM2.5 PSD Increment-Significant Impact Levels (SILs)-

1 “Final Rule To Implement the 8-Hour Ozone National Ambient Air Quality Standard—Phase 2; Final Rule” 

(November 29, 2005, 70 FR 71612) (hereafter referred to as the “Phase II Rule”).

2 Prevention of Significant Deterioration and Title V Greenhouse Gas (GHG) Tailoring Rule; Final Rule” (June 3, 

2010, 75 FR 31514) (hereafter referred to as the “GHG Tailoring Rule”).

3 Utility Air Regulatory Group v. Environmental Protection Agency, 134 S. Ct. 2427 (2014).

4 Implementation of the New Source Review Program for Particulate Matter Less Than 2.5 Micrometers; Final 

Rule” (May 16, 2008, 73 FR 28321) (hereafter referred to as the “NSR PM2.5 Rule”).

 
Significant Monitoring Concentrations (SMC) Rule (only as it relates to PM2.5 Increments).

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Specific details on these PSD requirements can be found in the respective final rules cited above, 

however, a brief summary of each rule is provided below. 

The Phase II rule established Federal NSR permitting requirements for the 

implementation of the ozone NAAQS including recognizing nitrogen oxide as an ozone 

precursor. See 70 FR 71612.

The GHG Tailoring Rule established emission thresholds for determining which new 

stationary sources and modification projects become subject to PSD permitting requirements for 

their GHG emissions. See 75 FR 31514. EPA notes that on June 23, 2014, the United States

(U.S.) Supreme Court issued a decision addressing the application of PSD permitting 

requirements to GHG emissions. See Utility Air Regulatory Group v. Environmental Protection 

Agency, 134 S. Ct. 2427. In that decision, the Supreme Court said that the EPA may not treat 

GHGs as an air pollutant for purposes of determining whether a source is a major source required 

to obtain a PSD permit. The Court also said that the EPA could continue to require that PSD 

permits, otherwise required based on emissions of pollutants other than GHGs, contain 

limitations on GHG emissions based on the application of Best Available Control Technology 

(BACT).

In accordance with the Supreme Court decision, on April 10, 2015, the U.S. Court of 

Appeals for the District of Columbia Circuit (D.C. Circuit) issued an Amended Judgment 

(Coalition for Responsible Regulation, Inc. v. EPA, Nos. 09-1322, 10-073, 10-1092 and 10-

5 “Final Rule on the Prevention of Significant Deterioration (PSD) for Particulate Matter Less Than 2.5 Micrometers 

(PM2.5) – Increments, Significant Impact Levels (SILs) and Significant monitoring Concentration (SMC); Final 

Rule” (October 20, 2010, 75 FR 64864) (hereafter referred to as the“PM2.5 PSD Increment-SILs-SMC Rule (only as 

it relates to PM2.5 Increments)”).

 
1167), vacating the regulations that implemented Step 2 of EPA’s GHG Tailoring Rule, but not 

the regulations that implement Step 1 of that rule. Step 1 of the GHG Tailoring Rule covers 

sources that are required to obtain a PSD permit based on emissions of pollutants other than 

GHGs. Step 2 applied to sources that emitted only GHGs above the thresholds triggering the 

requirement to obtain a PSD permit. The Amended Judgment preserves, without the need for 

additional rulemaking by the EPA, the application of the BACT requirement to GHG emissions 

from Step 1 or “anyway” sources. With respect to Step 2 sources, the D.C. Circuit’s Amended 

Judgment vacated the regulations at issue in the litigation, including 40 CFR 51.166(b)(48)(v) 

and 40 CFR 52.21(b)(49)(v), “to the extent they require a stationary source to obtain a PSD 

permit if greenhouse gases are the only pollutant (i) that the source emits or has the potential to 

emit above the applicable major source thresholds, or (ii) for which there is a significant 

emission increase from a modification.” The D.C. Circuit simultaneously issued its mandate, 

which means that the Coalition Amended Judgment became final and effective upon issuance.

On August 12, 2015, EPA signed a final rule that removes from the PSD regulations 

certain regulatory provisions that require a stationary source to obtain a PSD permit solely on the 

basis of the source’s GHG emissions (Step 2) and the regulations that require the EPA to 

consider further phasing in GHG permitting requirements into the PSD. The EPA intends to 

further revise the PSD regulations to fully implement the Coalition Amended Judgment in a 

separate rulemaking. States may submit revisions to their PSD SIP program consistent with 

EPA’s amended regulations whenever feasible. At this juncture, EPA is not expecting states to 

have revised their PSD programs for purposes of infrastructure SIP submissions and is only 

evaluating such submissions to assure that the state’s program correctly addresses GHGs 

consistent with the court decisions discussed above and EPA’s revised regulations.
The 2008 NSR PM2.5 Rule6 and 2010 PM2.5 PSD Increment-SILs-SMC Rule (only as it 

relates to PM2.5 Increments) established NSR permitting requirements for the implementation of 

the PM2.5 NAAQS including increments pursuant to section 166(a) of the CAA to prevent 

significant deterioration of air quality in areas meeting the NAAQS. See 73 FR 28321 and 75 FR 

64864. On January 22, 2013, the D.C. Circuit, in Sierra Club v. EPA, 703 F.3d 458 (D.C. Cir. 

2013), issued a judgment that, among other things, vacated the provisions adding the PM2.5 SMC 

to the Federal regulations, at 40 CFR 51.166(i)(5)(i)(c) and 52.21(i)(5)(i)(c), that were

promulgated as part of the 2010 PM2.5 PSD Increment-SILs-SMC Rule.7 See 75 FR 64864; see

also, Sierra Club v. EPA, 703 F.3d 458 (D.C. Cir. 2013). In its decision, the court held that EPA 

did not have the authority to use SMCs to exempt permit applicants from the statutory 

requirement in section 165(e)(2) of the CAA that ambient monitoring data for PM2.5 be included 

6 On January 4, 2013, the U.S. Court of Appeals, in Natural Resources Defense Council v. EPA, No. 08-1250, 2013 

WL 45653 (D.C. Cir., filed July 15, 2008) (consolidated with 09-1102, 11-1430), issued a judgment that remanded 

EPA’s 2007 and 2008 rules implementing the PM2.5 NAAQS. The court concluded that since subpart 4 of the CAA 

generally applies to coarse particulate matter (PM10), EPA should have also followed the more prescriptive subpart 4 

structure for the PM2.5 implementation rules. The court ordered EPA to repromulgate the implementation rules 

pursuant to subpart 4. Subpart 4 of part D, title 1 of the CAA establishes additional provisions for particulate matter 

nonattainment areas.

The 2008 implementation rule addressed by the court decision, “Implementation of New Source Review (NSR) 

Program for Particulate Matter Less Than 2.5 Micrometers (PM2.5),” 73 FR 28321 (May 16, 2008), promulgated 

NSR requirements for implementation of PM2.5 in both nonattainment areas (NNSR) and attainment/unclassifiable 

areas (PSD). As the requirements of subpart 4 only pertain to nonattainment areas, EPA does not consider the 

portions of the 2008 rule that address requirements for PM2.5 attainment and unclassifiable areas to be affected by 

the court’s opinion. Moreover, EPA does not anticipate the need to revise any PSD requirements promulgated in the 

2008 rule in order to comply with the court’s decision. Accordingly, EPA’s approval of a state’s infrastructure SIP 

related to elements (C), (D)(i) (prong 3), or (J) with respect to the PSD requirements promulgated in the 2008 NSR 

PM2.5 Rule does not conflict with the court’s opinion.

The court’s decision with respect to the NNSR requirements promulgated by the 2008 implementation rule also does 

not affect EPA’s action on the present infrastructure actions. EPA interprets the Act to exclude nonattainment area 

requirements, including requirements associated with a nonattainment NSR program, from infrastructure SIP 

submissions due three years after adoption or revision of a NAAQS. Instead, these elements are typically referred to 

as nonattainment SIP or attainment plan elements, which would be due by the dates statutorily prescribed under 

subpart 2 through 5 under part D, extending as far as 10 years following designations for some elements. 

7 “Prevention of Significant Deterioration (PSD) for Particulate Matter Less Than 2.5 Micrometers (PM2.5)—

Increments, Significant Impact Levels (SILs) and Significant Monitoring Concentration (SMC)”; Final Rule, 75 FR 

64864 (October 20, 2010), (hereafter referred to as the “2010 PM2.5 PSD Increment-SILs-SMC Rule”).

 
in all PSD permit applications. Thus, although the PM2.5 SMC was not a required element of a 

state’s PSD program and thus not a structural requirement for purposes of infrastructure SIPs, 

were a SIP-approved PSD program that contains such a provision to use that provision to issue 

new permits without requiring ambient PM2.5 monitoring data, such application of the SIP would 

be inconsistent with the court’s opinion and the requirements of section 165(e)(2) of the CAA. 

EPA approved the SMC’s into the Mississippi SIP on September 26, 2012 (77 FR 

59095). However, given the clarity of the court’s decision, it would now be inappropriate for 

Mississippi to continue to allow applicants for any pending or future PSD permits to rely on the 

PM2.5 SMC in order to avoid compiling ambient monitoring data for PM2.5. Because of the 

vacatur of the EPA regulations, the SMC provisions, included in Mississippi’s SIP-approved 

PSD program on the basis of EPA’s regulations, are unlawful and no longer enforceable by law. 

Permits issued on the basis of these provisions as they appear in Mississippi’s federally-approved 

SIP would be inconsistent with the CAA and difficult to defend in administrative and judicial 

challenges. Thus, the SIP provisions may not be applied even prior to their removal from the 

SIP. Mississippi should instead require applicants requesting a PSD permit, including those 

having already been applied for but for which the permit has not yet been received, to submit 

ambient PM2.5 monitoring data in accordance with the CAA requirements whenever either direct 

PM2.5 or any PM2.5 precursor is emitted in a significant amount.8

8

 In lieu of the applicants’ need to set out PM2.5 monitors to collect ambient data, applicants may submit PM2.5

ambient data collected from existing monitoring networks when the permitting authority deems such data to be 

representative of the air quality in the area of concern for the year preceding receipt of the application. EPA 

believes that applicants will generally be able to rely on existing representative monitoring data to satisfy the 

monitoring data requirement.

 
On December 9, 2013, EPA issued a final rulemaking to remove the vacated and 

remanded PM2.5 SILs9 and the vacated PM2.5 SMC provisions from 40 CFR 51.166 and 52.21.10 

See 79 FR 73698. Because the Court vacated the PM2.5 SMC provisions in 40 CFR 

51.166(i)(5)(i)(c) and 52.21(i)(5)(i)(c), EPA revised the existing concentration for the PM2.5 

SMC listed in sections 51.166(i)(5)(i)(c) and 52.21(i)(5)(i)(c) to zero micrograms per cubic 

meter (mg/m3). Were EPA to completely remove PM2.5 from the list of pollutants in sections 

51.166(i)(5)(i)(c) and 52.21(i)(5)(i)(c) of the PSD regulations, PM2.5 would no longer be a listed 

pollutant.

EPA did not entirely remove PM2.5 as a listed pollutant in the SMC provisions so as to 

avoid any potential that sections 51.166(i)(5)(iii) and 52.21(i)(5)(iii) could be interpreted as 

giving reviewing authorities the discretion to exempt permit applicants from the requirement to 

conduct monitoring for PM2.5. Such a conclusion would contravene the Court’s decision and the 

CAA.

By continuing to include PM2.5 as a pollutant in the list contained in sections 

51.166(i)(5)(i) and 52.21(i)(5)(i), with the numerical value replaced with zero mg/m3, EPA is 

avoiding any concern that paragraph (iii) of the two affected sections could be applied to excuse 

permit applicants from adequately addressing the monitoring requirement for PM2.5.

EPA also advises states to begin preparations to remove the PM2.5 provisions from their 

state PSD regulations and SIPs. As the previously-approved PM2.5 SMC SIP provisions are no 

9 The court’s January 22, 2013, decision also vacated and remanded back to EPA the PM2.5 SILs. EPA’s December 

9, 2013, final rule also removed the PM2.5 SILs from the CFR. The PM2.5 SILs are not a required element of a 

state’s PSD program and thus not a structural requirement for purposes of infrastructure SIPs. The PM2.5 SILs are 

not approved into the SIP revision that is the subject of this proposed rulemaking.

10 Final Rule entitled “Prevention of Significant Deterioration for Particulate Matter Less Than 2.5

Micrometers—Significant Impact Levels and Significant Monitoring Concentration: Removal of Vacated

Elements;” 79 FR 73698 (December 9, 2013).

 
longer enforceable, EPA does not believe the existence of these provisions in SIPs preclude

approval of the infrastructure SIP submissions.

EPA also advises states to begin preparations to remove the PM2.5 provisions from their 

state PSD regulations and SIPs. As the previously-approved PM2.5 SMC provisions in the 

Mississippi SIP are no longer enforceable, EPA does not believe the existence of these

provisions in the State’s implementation plan precludes approval of the infrastructure SIP 

submission for Mississippi.

EPA’s Analysis of How Mississippi Addressed Sections 110(a)(2)(C), 

110(a)(2)(D)(i)(II)(prong 3), and 110(a)(2)(J) related to PSD

Described below is EPA’s analysis of how the Mississippi infrastructure SIP submission 

meets the requirements of the PSD elements for the NAAQS for which it was submitted. This 

analysis includes review of the EPA’s previous approval of the four structural PSD program 

requirements which is summarized in Table 1 below. 

Table 1. EPA-Approved Structural PSD Program Requirements for Mississippi

State Phase II Rule GHG Tailoring 

Rule

NSR PM2.5 Rule PM2.5 PSD 

Increment-SILsSMC Rule

Mississippi December 20, 2010

(75 FR 79300)

December 29, 2010 

(75 FR 81858)

September 26, 2012 

(77 FR 59095)

September 26, 2012 

(77 FR 59095)