STATE OF NORTH CAROLINA 

DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES 

DIVISION OF AIR QUALITY 

REPORT OF PROCEEDINGS OF PUBLIC HEARING 

ON PROPOSED AMENDMENT TO 

 RULES 15A NCAC 02D .0530, PREVENTION OF 

SIGNIFICANT DETERIORATION AND 

15A NCAC 02D .0531, SOURCES IN NONATTAINMENT AREAS 

(NSR AND PSD NOx SIGNIFICANCE LEVEL FOR PM2.5 AND PM2.5 

INCREMENTS) 

 

 

 

JANUARY 15, 2013 

KANNAPOLIS, NC 

ENVIRONMENTAL MANAGEMENT COMMISSION 

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CONTENTS 

CHAPTER I Summaries and Recommendations I-1

Background and Summary I-1

Comments and Responses Thereto I-2

Summary of Comments and Responses I-4

Conclusion I-4

Hearing Officers’ Recommendation I-5

CHAPTER II Rules Proposed for Adoption II-1

CHAPTER III Report of Proceedings III-1

Introduction III-1

Designation of Hearing Officer III-2

Public Notice III-3

Transcript III-5

CHAPTER IV Exhibits IV- 1

Proposed Rules as Presented at the Hearing 

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Hearing Officer Comments at Hearing IV-10

CHAPTER V Written Comments During Comment Period V-1

CHAPTER VI Attachments VI-1

CHAPTER VII Documentation VII-1

 

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CHAPTER I 

Summaries and Recommendations 

Proposed amendment to Rules 15A NCAC 02D .0530 and .0531. 

BACKGROUND AND SUMMARY 

 

A public hearing was held in Kannapolis, NC on January 15, 2013, to take public comments on 

amendments to 15A NCAC 02D .0530 and .0531. Mr. Benne Hutson was appointed and acted as 

the hearing officer for this hearing. 

The EMC amended the New Source Review (NSR) and Prevention of Significant Deterioration 

(PSD) permitting rules in 2010 to establish the significance level for nitrogen oxides (NOx) for 

fine particulate matter in North Carolina at 140 tons per year (tpy). Fine Particulate Matter 

(PM2.5) is particles less than 2.5 micrometers in diameter and is interchangeably referred to as 

"fine" particles. This significance level was based on monitoring and modeling data indicating 

that NOx is a lessor contributor to the formation of PM2.5 than sulfur dioxide (SO2). As part of its 

rule review of North Carolina’s state implementation plan (SIP), the United States 

Environmental Protection Agency (EPA) has determined that, while the federal rule allows for a 

demonstration that NOx is not a significant precursor to formation of PM2.5, there is not an 

allowance for states to establish an alternate significance level. As a result, the state significance 

level must be revised to reflect the federal 40 tpy significance level in the EPA PM2.5 

Implementation Rule. 

In 2010, the EPA added PM2.5 increments under the program. An increment is the maximum 

allowable increase in ambient pollutant concentration. Federal increments were established for 

24-hour and annual averaging periods in Class I, Class II and Class III areas. Adoption of these 

federal increments is required in order for the EPA to approve North Carolina’s SIP. The current 

date of incorporation in the state rule needs to be updated to reflect the current PM2.5 increments 

for the current annual and 24-hour NAAQS established by the EPA. 

15A NCAC 02D .0530, Prevention of Significant Deterioration, is proposed for amendment to 

revise North Carolina’s NOx significance level from 140 tons per year to 40 tons per year and to 

update the federal cross-reference to reflect the current federal increments for PM2.5. 

15A NCAC 02D .0531 Sources in Nonattainment Areas, is proposed for amendment to revise 

North Carolina’s NOx significance level from 140 tons per year to 40 tons per year. 

During the public comment period, there were two court decisions that were issued on the 

implementation of PM2.5 regulations. The first court decision was the U.S. Court of Appeals for 

the District of Columbia Circuit, January 4, 2013, Sierra Club vs. EPA, No. 08-1250. The court 

reviewed of the PM2.5 Implementation Rule, 72 FR 20586 (4/25/2007) and PM2.5 NSR 

Implementation Rule, 73 FR 28321 (5/16, 2008). The petitioners challenge was EPA decision to 

promulgate its PM2.5 implementation rules pursuant to Subpart 1 of Part D of Title I which 

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contains the implementation provisions for nonattainment areas in general rather than Subpart 4 

of Part D of Title I which contains implementation provisions specific to PM10. Subpart 4 is 

specific to PM10. The court decision remanded the two implementation rules to EPA to 

repromulgate them pursuant to Subpart 4 of Part D of Title I of the Clean Air Act. 

The second court decision was the U.S Court of Appeals for the District of Columbia Circuit, 

January 22, 2013, National Resources Defense Council and Sierra Club vs. EPA, No. 10-1413. 

The court reviewed of the PM2.5 Increments, Significant Impact Levels (SIL) and Significant 

Monitoring Concentration (SMC) final rule in 75 FR 64864 (October 20, 2010). Specifically, the 

court reviewed the adoption of the SIL and SMC screening tools EPA uses to determine whether 

a new source may be exempted from certain requirements under 40 CFR 51.165, Permit 

requirements. 

The SILs sets a de minimis ambient impact where a source’s impact that is below a SIL is not 

required to conduct more extensive modeling to demonstrate its emission will not contribute to a 

violation of the NAAQS. The SMC sets a de minimis concentration where a source can show 

through modeling that its impacts are less than the SMC, eliminating the requirement to collect 

additional monitoring data. The court decision vacated and remanded the SILs under 40 CFR 

51.166(k)(2) and 40 CFR 52.21(k)(2) for further consideration by EPA. The decision also 

vacated the parts of the rule establishing the SMCs due to EPA exceeding its statutory authority. 

The court decisions are included in Chapter VI of the hearing record. 

PUBLIC COMMENTS AND RESPONSES THERETO

Comment: Mr. Huncik commented that incorporation by reference of the October 20, 2010 

Rule as proposed under 15A NCAC 2D .0530(v) should be delayed or revised due to the recent 

US Court of Appeals for the DC Circuit decision (attached) which directly affects the 

implementation of the PM2.5 standard. Specifically, EPA has contended that PM2.5 should be 

treated as a "new pollutant" with new baseline dates. However, the Court refuted this approach 

in their January 4, 2013 decision. Therefore, the incorporation by reference of the October 20, 

2010 Rule which sets a new PM2.5 trigger date and baseline dates is not consistent with the CAA 

and with the Court's decision. It is important to note that in 1998 the EPA handled PM10

consistent with the CAA when they retained the original 1977 baseline date for particulate. 

Mr. Huncik also commented that in the October 20, 2010 preamble, EPA stated that "..For early 

minor source baseline dates...establishing the emissions inventory for PM2.5 would be extremely 

difficult, cumbersome, and potentially inaccurate..." However, difficulty in acquiring or 

developing data is not specific enough for such a significant rule change (i.e., change in trigger 

date and baseline dates). EPA must adhere to basic standards, including gathering and sharing 

supporting policy-relevant data, that it bases regulatory changes on. In addition, statements or 

bases provided in a preamble do not constitute binding, final agency action, except in some 

unique cases. 

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Response: North Carolina Division of Air Quality (DAQ) recommends not adopting the 

October 20, 2010 EPA rule amendments by incorporation by reference at this time and leaving 

the May 16, 2008 prehearing incorporation by reference date unchanged. North Carolina DAQ 

will review EPA’s resolution to the January 4, 2013 US Court of Appeals for the DC Circuit 

decision when EPA repromulgates its rules pursuant to Subpart 4 consistent with the court’s 

opinion. 

Comment: R. Scott Davis of the EPA commented that the October 20, 2010, incorporation by 

reference date for 15A NCAC 02D .0530 does not capture the EPA's October 2012 final rule to 

amend the definition of "regulated NSR pollutant" promulgated in the 2008 NSR PM2.5 Rule 

regarding the PM condensable provision at 40 CFR 51.166(b)(49)(vi), 52.21(b)(50)(i) and the 

EPA's Emissions Offset Interpretative Ruling (See 77 FR 15656). The rulemaking removed the 

inadvertent requirement in the NSR PM2.5 Rule that the measurement of condensable "particulate 

matter emissions" be included as part of the measurement and regulation of "particulate matter 

emissions." The EPA suggests NC DENR provide a clarification letter indicating the 

department's intentions regarding the term "particulate matter emissions" for the definition of 

"regulated NSR pollutant" concerning condensable emissions. 

Response: North Carolina DAQ defines particulate matter, PM10, and PM2.5 in Rule 15A 

02D .0101, Definitions. North Carolina DAQ relies on the test methods in Rule 15A NCAC 02D 

.2609, Particulate Testing Methods, to determine the measurement of specific particulate matter 

pollutants. North Carolina DAQ will include a clarification letter with its SIP submittal. 

Comment: R. Scott Davis of the EPA commented that regarding the North Carolina 

Department of Environment and Natural Resources proposed State Implementation Plan (SIP) 

revision at 15A NCAC 02D .0530 to incorporate by reference (IBR) the PM2.5 SILs at 40 CFR 

52.21(k)(2) and Significant Monitoring Concentration at 52.21(i)(5), the U.S . Environmental 

Protection Agency's authority to implement the PM2.5 SILs and SMC for PSD purposes as 

promulgated in the October 20, 2010, was challenged by the Sierra Club, Sierra Club v. EPA, 

Case No 10-1413 (D.C. Circuit). On January 22, 2013 , the court issued an order vacating and 

remanding to the EPA for further consideration the portions of its 2010 rule addressing the PM2.5

SILs, except for the parts codifying the PM2.5 SILs in the NSR rule at 40 CFR 51.165(b)(2) . The 

court also vacated the parts of the 2010 rule establishing the PM2.5 SMC on the grounds that 

those parts of the rule exceed the EPA's statutory authority. Due to the court's decision, the EPA 

cannot approve any SIP submission containing the parts of the state's PSD regulations 

authorizing the PM2.5 SILs and SMC that are consistent with the PSD regulations at 40 CFR 

51.166 and 52.21 which the court has vacated. Accordingly, the EPA recommends that NC 

DENR not continue with rulemaking on these two provisions. 

Response: North Carolina DAQ recommends not continuing with rulemaking on these two 

provisions at this time. The rulemaking also includes amending the NOx significance level for 

PM2.5 from 140 tons per year in the current rule to 40 tons per year that is specified in 40 CFR 

51.166(b)(23)(i) and the adding the PM2.5 increments that were adopted by EPA in 40 CFR 

51.166(c)(1) in its October 20, 2010 (75 FR 64864) rulemaking. The proposed rule incorporated 

the PM2.5 increments by reference. Due to the Court Decision on January 22, 2013 vacating and 

remanding the PM2.5 SILs and SMC, North Carolina DAQ recommends leaving the May 16, 

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2008 incorporation by reference date unchanged and explicitly adding the PM2.5 and PM10

increments as indicators of particulate matter as Paragraph (v) of the 15A NCAC 02D .0530 

since increments are a required element for an approvable SIP. 

Comment: R. Scott Davis of the EPA commented that NC DENR's current proposed revision 

at 15A NCAC 02D .0530 to update the IBR date of 40 CFR 52.21 to October 20, 2010, does not 

include the May 18, 2011 (76 FR 28646) repeal of the PM2.5 grandfathering provision at 40 CFR 

52.21(i)(l)(xi). The repeal ended the use of the 1997 PM10 Surrogate Policy for PSD permits 

under the federal PSD program at 40 CFR 52.21. The current version of 15A NCAC 02D .0530 

proposed for revision includes the 2008 grandfather provision. The EPA will not take action to 

approve the grandfathering provision into the North Carolina SIP in accordance with the May 18, 

2011 repeal. 

Response: The North Carolina rule does not reference the grandfathering provision in 40 

CFR 52.21(i)(1)(xi). North Carolina has an approved program under 40 CFR 51.166. 40 CFR 

52.21 contains requirements implementing PSD provisions for States without an EPA-approved 

SIP. Therefore NC is not required to incorporate the May 18, 2011 repeal of the grandfathering 

provision in 40 CFR 52.21 since the provisions of 40 CFR 51.166 apply to the North Carolina 

PSD program and its rule does not reference 40 CFR 52.21. 

SUMMARY OF COMMENTS AND RESPONSES

Comments Response

Delay or revise the incorporation by reference 

date of October 20, 2010 due to the US Court of 

Appeals for the DC Circuit decision on January 4, 

2013.

Amend the proposed rule to remove the 

incorporation by reference date of October 20, 

2010 and keep the prehearing May 16, 2008 

incorporation by reference date.

Discontinue rulemaking on PM2.5 SILs and SMC. Incorporate May 16, 2008 version of CFR. Add 

PM2.5 increments to the rule explicitly instead of 

incorporation by reference of the October 20, 

2010 EPA final rule containing SILs and SMC.

Clarify “particulate matter emissions” for the 

definition of "regulated NSR pollutant" 

concerning condensable emissions

Send clarification letter on particulate matter 

with SIP submittal.

Proposed rule does not include the May 18, 2011

PM2.5 grandfathering provision repeal in 40 CFR 

52.21(i)(l)(xi).

North Carolina does not reference this 

grandfathering provision in its rules. No change 

in rule. 

CONCLUSION

Two people commented on the proposed rules. During the comment period, there were also two 

U.S. Court of Appeals decisions that affected the EPA’s implementation of PM2.5 regulations. 

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One person commented that the North Carolina Division of Air Quality (DAQ) delay or revise 

the October 20, 2010 incorporation by reference date in the proposed rule. One person requested 

that DAQ not continue rulemaking on adding the significant impact levels and significant 

monitoring concentration provisions to North Carolina PSD regulations. The proposed rule was 

amended to remove the incorporation by reference date of October 20, 2010 and keep the 

prehearing May 16, 2008 incorporation by reference date. DAQ also explicitly added the PM2.5

and PM10 increments as indicators of particulate matter in Paragraph (v) of Rule 15A NCAC 

02D .0530 since increments are a required element for an approvable SIP. 

One person asked DAQ to clarify “particulate emissions” in the definition of “regulated NSR 

pollutant” since Rule 15A NCAC 02D .0530 does not capture EPA’s October 25, 2012 final rule 

amending the definition of “regulated NSR pollutant. DAQ relies on the test methods in Rule 

15A NCAC 02D .2609 to determine the measurement of specific particulate matter pollutants. 

North Carolina DAQ will include a clarification letter with its SIP submittal. 

One person commented that the proposed rule does not include the May 18, 2011 PM2.5

grandfathering provision repeal in 40 CFR 52.21(i)(l)(xi). DAQ does not reference this 

grandfathering provision in its rules. No changes were made in the proposed rule. 

The fiscal impact of SILs and SMC provisions in EPA’s October 20, 2010 final PM2.5

implementation rule were included in the fiscal note for the proposed PSD rule. EPA’s SILs and 

SMC provisions were vacated by the January 22, 2013 U.S. Court of Appeals decision. 

Removing the SILs and SMC from DAQ’s proposed rule did not change the fiscal impact 

calculations in the approved fiscal note. 

HEARING OFFICERS’ RECOMMENDATION

The Hearing Officers recommend that the proposed amendment as presented in Chapter II of this 

hearing report be adopted by the Environmental Management Commission. 

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1 CHAPTER II 

2

3 15A NCA 02D .0530 is proposed for amendment with changes as follows: 

4

5 15A NCAC 02D .0530 PREVENTION OF SIGNIFICANT DETERIORATION 

6 (a) The purpose of the Rule is to implement a program for the prevention of significant deterioration of air quality 

7 as required by 40 CFR 51.166. 

8 (b) For the purposes of this Rule the definitions contained in 40 CFR 51.166(b) and 40 CFR 51.301 apply except 

9 the definition of "baseline actual emissions." For the purposes of this Rule: 

10 (1) "Baseline actual emissions" means the rate of emissions, in tons per year, of a regulated new 

11 source review (NSR) pollutant, as determined in accordance with Parts (A) through (C) of this 

12 Subparagraph: 

13 (A) For an existing emissions unit, baseline actual emissions means the average rate, in tons 

14 per year, at which the emissions unit actually emitted the pollutant during any 

15 consecutive 24-month period selected by the owner or operator within the 5-year period 

16 immediately preceding the date that a complete permit application is received by the 

17 Division for a permit required under this Rule. The Director shall allow a different time 

18 period, not to exceed 10 years immediately preceding the date that a complete permit 

19 application is received by the Division, if the owner or operator demonstrates that it is 

20 more representative of normal source operation. For the purpose of determining baseline 

21 actual emissions, the following apply:

22 (i) The average rate shall include fugitive emissions to the extent quantifiable, and 

23 emissions associated with startups, shutdowns, and malfunctions; 

24 (ii) The average rate shall be adjusted downward to exclude any non-compliant 

25 emissions that occurred while the source was operating above any emission 

26 limitation that was legally enforceable during the consecutive 24-month period; 

27 (iii) For an existing emission unit (other than an electric utility steam generating 

28 unit), the average rate shall be adjusted downward to exclude any emissions that 

29 would have exceeded an emission limitation with which the major stationary 

30 source must currently comply. However, if the State has taken credit in an 

31 attainment demonstration or maintenance plan consistent with the requirements 

32 of 40 CFR 51.165(a)(3)(ii)(G) for an emission limitation that is part of a 

33 maximum achievable control technology standard that the Administrator 

34 proposed or promulgated under part 63 of the Code of Federal Regulations, the 

35 baseline actual emissions shall be adjusted to account for such emission 

36 reductions; 

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1 (iv) For an electric utility steam generating unit, the average rate shall be adjusted 

2 downward to reflect any emissions reductions under G.S. 143-215.107D and for 

3 which cost recovery is sought pursuant to G.S. 62-133.6; 

4 (v) For a regulated NSR pollutant, when a project involves multiple emissions units, 

5 only one consecutive 24-month period shall be used to determine the baseline 

6 actual emissions for all the emissions units being changed. A different 

7 consecutive 24-month period for each regulated NSR pollutant can be used for 

8 each regulated NSR pollutant; and 

9 (vi) The average rate shall not be based on any consecutive 24-month period for 

10 which there is inadequate information for determining annual emissions, in tons 

11 per year, and for adjusting this amount if required by Subparts (ii) and (iii) of 

12 this Part; 

13 (B) For a new emissions unit, the baseline actual emissions for purposes of determining the 

14 emissions increase that will result from the initial construction and operation of such unit 

15 shall equal zero; and thereafter, for all other purposes, shall equal the unit's potential to 

16 emit; and 

17 (C) For a plantwide applicability limit (PAL) for a stationary source, the baseline actual 

18 emissions shall be calculated for existing emissions units in accordance with the 

19 procedures contained in Part (A) of this Subparagraph, and for a new emissions unit in 

20 accordance with the procedures contained in Part (B) of this Subparagraph; 

21 (2) In the definition of "net emissions increase," the reasonable period specified in 40 CFR 

22 51.166(b)(3)(ii) is seven years; 

23 (3) The limitation specified in 40 CFR 51.166(b)(15)(ii) does not apply; and 

24 (4) Particulate matter PM2.5 significant levels in 40 CFR 51.166(b)(23)(i) are incorporated by 

25 reference except as otherwise provided in this Rule. A net emission increase or the potential of a 

26 source to emit nitrogen oxide emissions shall be significant if the rate of emissions would equal or 

27 exceed 140 tons per year. Sulfur dioxide and nitrogen oxides are precursor to PM2.5 in all 

28 attainment and unclassifiable areas. Volatile organic compounds and ammonia are not significant 

29 precursors to PM2.5. 

30 (c) All areas of the State are classified as Class II except that the following areas are Class I: 

31 (1) Great Smoky Mountains National Park; 

32 (2) Joyce Kilmer Slickrock National Wilderness Area; 

33 (3) Linville Gorge National Wilderness Area; 

34 (4) Shining Rock National Wilderness Area; and 

35 (5) Swanquarter National Wilderness Area. 

36 (d) Redesignations of areas to Class I or II may be submitted as state proposals to the Administrator of the 

37 Environmental Protection Agency (EPA), if the requirements of 40 CFR 51.166(g)(2) are met. Areas may be 

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1 proposed to be redesignated as Class III, if the requirements of 40 CFR 51.166(g)(3) are met. Redesignations may 

2 not, however, be proposed which would violate the restrictions of 40 CFR 51.166(e). Lands within the boundaries of 

3 Indian Reservations may be redesignated only by the appropriate Indian Governing Body. 

4 (e) In areas designated as Class I, II, or III, increases in pollutant concentration over the baseline concentration shall 

5 be limited to the values set forth in 40 CFR 51.166(c). 51.166(c) and Paragraph (v) of this Rule. However, 

6 concentration of the pollutant shall not exceed standards set forth in 40 CFR 51.166(d). 

7 (f) Concentrations attributable to the conditions described in 40 CFR 51.166(f)(1) shall be excluded in determining 

8 compliance with a maximum allowable increase. However, the exclusions referred to in 40 CFR 51.166(f)(1)(i) or 

9 (ii) shall be limited to five years as described in 40 CFR 51.166(f)(2). 

10 (g) Major stationary sources and major modifications shall comply with the requirements contained in 40 CFR 

11 51.166(i) and (a)(7) and by extension in 40 CFR 51.166(j) through (o) and (w). The transition provisions allowed by 

12 40 CFR 52.21 (i)(11)(i) and (ii) and (m)(1)(vii) and (viii) are hereby adopted under this Rule. The minimum 

13 requirements described in the portions of 40 CFR 51.166 referenced in this Paragraph are hereby adopted as the 

14 requirements to be used under this Rule, except as otherwise provided in this Rule. Wherever the language of the 

15 portions of 40 CFR 51.166 referenced in this Paragraph speaks of the "plan," the requirements described therein 

16 shall apply to the source to which they pertain, except as otherwise provided in this Rule. Whenever the portions of 

17 40 CFR 51.166 referenced in this Paragraph provide that the State plan may exempt or not apply certain 

18 requirements in certain circumstances, those exemptions and provisions of nonapplicability are also hereby adopted 

19 under this Rule. However, this provision shall not be interpreted so as to limit information that may be requested 

20 from the owner or operator by the Director as specified in 40 CFR 51.166(n)(2). 

21 (h) New natural gas-fired electrical utility generating units for which cost recovery is sought pursuant to G. S. 62-

22 133.6 shall install best available control technology for NOX and SO2, regardless of applicability of the rest of this 

23 Rule. 

24 (i) 40 CFR 51.166(w)(10)(iv)(a) is changed to read: "If the emissions level calculated in accordance with Paragraph 

25 (w)(6) of this Section is equal to or greater than 80 percent of the PAL [plant wide applicability limit] level, the 

26 Director shall renew the PAL at the same level." 40 CFR 51.166(w)(10)(iv)(b) is not incorporated by reference. 

27 (j) 15A NCAC 02Q .0102 and .0302 are not applicable to any source to which this Rule applies. The owner or 

28 operator of the sources to which this Rule applies shall apply for and receive a permit as required in 15A NCAC 

29 02Q .0300 or .0500. 

30 (k) When a particular source or modification becomes a major stationary source or major modification solely by 

31 virtue of a relaxation in any enforceable limitation which was established after August 7, 1980, on the capacity of 

32 the source or modification to emit a pollutant, such as a restriction on hours of operation, then the provisions of this 

33 Rule shall apply to the source or modification as though construction had not yet begun on the source or 

34 modification. 

35 (l) The provisions of 40 CFR 52.21(r)(2) regarding the period of validity of approval to construct are incorporated 

36 by reference except that the term "Administrator" is replaced with "Director". 

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1 (m) Volatile organic compounds exempted from coverage in 40 CFR 51.100(s) shall be exempted when calculating 

2 source applicability and control requirements under this Rule. 

3 (n) The degree of emission limitation required for control of any air pollutant under this Rule shall not be affected 

4 by: 

5 (1) that amount of a stack height, not in existence before December 31, 1970, that exceeds good 

6 engineering practice; or 

7 (2) any other dispersion technique not implemented before then. 

8 (o) A substitution or modification of a model as provided for in 40 CFR 51.166(l) is subject to public comment 

9 procedures in accordance with the requirements of 40 CFR 51.102. 

10 (p) Permits may be issued on the basis of innovative control technology as set forth in 40 CFR 51.166(s)(1) if the 

11 requirements of 40 CFR 51.166(s)(2) have been met, subject to the condition of 40 CFR 51.166(s)(3), and with the 

12 allowance set forth in 40 CFR 51.166(s)(4). 

13 (q) If a source to which this Rule applies impacts an area designated Class I by requirements of 40 CFR 51.166(e), 

14 notice to EPA shall be provided as set forth in 40 CFR 51.166(p)(1). If the Federal Land Manager presents a 

15 demonstration described in 40 CFR 51.166(p)(3) during the public comment period or public hearing to the Director 

16 and if the Director concurs with this demonstration, the permit application shall be denied. Permits may be issued on 

17 the basis that the requirements for variances as set forth in 40 CFR 51.166(p)(4), (p)(5) and (p)(7), or (p)(6) and 

18 (p)(7) have been satisfied. Pursuant to 40 CFR 51.166(p)(4), Class I Variances, the maximum allowable increases in 

19 micrograms per cubic meter over minor source baseline concentration for particulate matter are as follows:

Class I variances – Particulate Matter

Indicator Averaging Period micrograms per cubic meter

PM2.5 Annual arithmetic mean 4

PM2.5 24 hour maximum 9

PM10 Annual arithmetic mean 17

PM10 24 hour maximum 30

20

21 (r) A permit application subject to this Rule shall be processed in accordance with the procedures and requirements 

22 of 40 CFR 51.166(q). Within 30 days of receipt of the application, applicants shall be notified if the application is 

23 complete as to initial information submitted. Commencement of construction before full prevention of significant 

24 deterioration approval is obtained constitutes a violation of this Rule. 

25 (s) Approval of an application with regard to the requirements of this Rule does not relieve the owner or operator of 

26 the responsibility to comply with applicable provisions of other rules of this Subchapter or Subchapter 02Q of this 

27 Title and any other requirements under local, state, or federal law. 

28 (t) When a source or modification is subject to this Rule the following procedures apply: 

29 (1) Notwithstanding any other provisions of this Paragraph, the Director shall, no later than 60 days 

30 after receipt of an application, notify the Federal Land Manager with the U.S. Department of 

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1 Interior and U.S. Department of Agriculture of an application from a source or modification 

2 subject to this Rule; 

3 (2) When a source or modification may affect visibility of a Class I area the Director shall provide 

4 written notification to all affected Federal Land Managers within 30 days of receiving the permit 

5 application or within 30 days of receiving advance notification of an application. The notification 

6 shall be at least 30 days prior to the publication of notice for public comment on the application. 

7 The notification shall include a copy of all information relevant to the permit application including 

8 an analysis provided by the source of the potential impact of the proposed source on visibility; 

9 (3) The Director shall consider any analysis concerning visibility impairment performed by the 

10 Federal Land Manager if the analysis is received within 30 days of notification. If the Director 

11 finds that the analysis of the Federal Land Manager fails to demonstrate to his satisfaction that an 

12 adverse impact on visibility will result in the Class I area, the Director shall provide in the notice 

13 of public hearing on the application, an explanation of his decision or notice as to where the 

14 explanation can be obtained; and 

15 (4) The Director may require monitoring of visibility in or around any Class I area by the proposed 

16 new source or modification when the visibility impact analysis indicates possible visibility 

17 impairment. 

18 (u) If the owner or operator of a source is using projected actual emissions to avoid applicability of prevention of 

19 significant deterioration requirements, the owner or operator shall notify the Director of the modification before 

20 beginning actual construction. The notification shall include: 

21 (1) a description of the project; 

22 (2) identification of sources whose emissions could be affected by the project; 

23 (3) the calculated projected actual emissions and an explanation of how the projected actual emissions 

24 were calculated, including identification of emissions excluded by 40 CFR 51.166(b)(40)(ii)(c); 

25 (4) the calculated baseline actual emissions and an explanation of how the baseline actual emissions 

26 were calculated; and 

27 (5) any netting calculations if applicable. 

28 If upon reviewing the notification, the Director finds that the project will cause a prevention of significant 

29 deterioration evaluation, then the Director shall notify the owner or operator of his findings. The owner or operator 

30 shall not make the modification until it has received a permit issued pursuant to this Rule. If a permit revision is not 

31 required pursuant to this rule, the owner or operator shall maintain records of annual emissions in tons per year, on a 

32 calendar year basis related to the modifications for 10 years following resumption of regular operations after the 

33 change if the project involves increasing the emissions unit's design capacity or its potential to emit the regulated 

34 NSR pollutant; otherwise these records shall be maintained for five years following resumption of regular operations 

35 after the change. The owner or operator shall submit a report to the director within 60 days after the end of each year 

36 during which these records must be generated. The report shall contain the items listed in 40 CFR 51.166(r)(6)(v)(a) 

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1 through (c). The owner or operator shall make the information documented and maintained under this Paragraph 

2 available to the Director or the general public pursuant to the requirements in 40 CFR 70.4(b)(3)(viii). 

3 (v) Increments. For particulate matter, the maximum allowable increases in micrograms per cubic meter over the 

4 baseline concentration for areas classified as Class I, Class II and Class III shall be as follows:

5

Increments - Particulate Matter

Indicator Averaging Period Class I Class II Class III

PM2.5 Annual arithmetic mean 1 4 8

PM2.5 24 hour maximum 2 9 18

PM10 Annual arithmetic mean 4 17 34

PM10 24 hour maximum 8 30 60

6

7 (v)(w) The references to the Code of Federal Regulations (CFR) in this Rule are incorporated by reference unless a 

8 specific reference states otherwise. The version of the CFR incorporated in this Rule is that as of May 16, 2008 at 

9 http://www.gpo.gov/fdsys/pkg/FR-2008-05-16/pdf/E8-10768.pdf [October 20, 2010 at

10 http://www.gpo.gov/fdsys/pkg/FR-2010-10-20/pdf/2010-25132.pdf] and does not include any subsequent 

11 amendments or editions to the referenced material. 

12

13 History Note: Authority G.S. 143-215.3(a)(1); 143-215.107(a)(3); 143-215.107(a)(5); 143-215.107(a)(7); 143-

14 215.108(b); 150B-21.6; 

15 Eff. June 1, 1981; 

16 Amended Eff. December 1, 1992; August 1, 1991; October 1, 1989; July 1, 1988; October 1, 

17 1987; June 1, 1985; January 1, 1985; February 1, 1983; 

18 Temporary Amendment Eff. March 8, 1994, for a period of 180 days or until the permanent rule is 

19 effective, whichever is sooner; 

20 Amended Eff. ; January 2, 2011; September 1, 2010; May 1, 2008; July 28, 2006; July 

21 1, 1997; February 1, 1995; July 1, 1994. 

22

23 15A NCA 02D .0531 is proposed for amendment as follows: 

24

25 15A NCAC 02D .0531 SOURCES IN NONATTAINMENT AREAS 

26 (a) For the purpose of this Rule the definitions contained in 40 CFR 51.165(a)(1) and 40 CFR 51.301 apply except 

27 the definition of "baseline actual emissions." For the purposes of this Rule: 

28 (1) "Baseline actual emissions" means the rate of emissions, in tons per year, of a regulated new 

29 source review (NSR) pollutant, as determined in accordance with Parts (A) through (C) of this 

30 Subparagraph: 

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II-7 

1 (A) For an existing emissions unit, baseline actual emissions means the average rate, in tons 

2 per year, at which the emissions unit actually emitted the pollutant during any 

3 consecutive 24-month period selected by the owner or operator within the 5-year period 

4 immediately preceding the date that a complete permit application is received by the 

5 Division for a permit required under this Rule. The Director shall allow a different time 

6 period, not to exceed 10 years immediately preceding the date that a complete permit 

7 application is received by the Division, if the owner or operator demonstrates that it is 

8 more representative of normal source operation. For the purpose of determining baseline 

9 actual emissions, the following apply: 

10 (i) The average rate shall include fugitive emissions to the extent quantifiable, and 

11 emissions associated with startups, shutdowns, and malfunctions; 

12 (ii) The average rate shall be adjusted downward to exclude any non-compliant 

13 emissions that occurred while the source was operating above any emission 

14 limitation that was legally enforceable during the consecutive 24-month period; 

15 (iii) For an existing emission unit (other than an electric utility steam generating 

16 unit), the average rate shall be adjusted downward to exclude any emissions that 

17 would have exceeded an emission limitation with which the major stationary 

18 source must currently comply. However, if the State has taken credit in an 

19 attainment demonstration or maintenance plan consistent with the requirements 

20 of 40 CFR 51.165(a)(3)(ii)(G) for an emission limitation that is part of a 

21 maximum achievable control technology standard that the Administrator 

22 proposed or promulgated under part 63 of the Code of Federal Regulations, the 

23 baseline actual emissions shall be adjusted to account for such emission 

24 reductions; 

25 (iv) For an electric utility steam generating unit, the average rate shall be adjusted 

26 downward to reflect any emissions reductions under G.S. 143-215.107D and for 

27 which cost recovery is sought pursuant to G.S. 62-133.6; 

28 (v) For a regulated NSR pollutant, when a project involves multiple emissions units, 

29 only one consecutive 24-month period shall be used to determine the baseline 

30 actual emissions for all the emissions units being changed. A different 

31 consecutive 24-month period for each regulated NSR pollutant; and 

32 (vi) The average rate shall not be based on any consecutive 24-month period for 

33 which there is inadequate information for determining annual emissions, in tons 

34 per year, and for adjusting this amount if required by Subparts (ii) and (iii) of 

35 this Part; 

36 (B) For a new emissions unit, the baseline actual emissions for purposes of determining the 

37 emissions increase that will result from the initial construction and operation of such unit 

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II-8 

1 shall equal zero; and thereafter, for all other purposes, shall equal the unit's potential to 

2 emit; and 

3 (C) For a plantwide applicability limit (PAL) for a stationary source, the baseline actual 

4 emissions shall be calculated for existing emissions units in accordance with the 

5 procedures contained in Part (A) of this Subparagraph, and for a new emissions unit in 

6 accordance with the procedures contained in Part (B) of this Subparagraph; 

7 (2) In the definition of "net emissions increase," the reasonable period specified in 40 CFR 

8 51.165(a)(1)(vi)(C)(1) is seven years; and 

9 (3) Particulate matter PM2.5 significant levels in 40 CFR 51.165(a)(1)(x)(A) are incorporated by 

10 reference except as otherwise provided in this Rule. A net emission increase or the potential of a 

11 source to emit nitrogen oxide emissions shall be significant if the rate of emissions would equal or 

12 exceed 140 tpy. Sulfur dioxide and nitrogen oxides are precursor to PM2.5 in all nonattainment 

13 areas. Volatile organic compounds and ammonia are not significant precursors to PM2.5. 

14 (b) Redesignation to Attainment. If any county or part of a county to which this Rule applies is later designated in 

15 40 CFR 81.334 as attainment, all sources in that county subject to this Rule before the redesignation date shall 

16 continue to comply with this Rule. 

17 (c) Applicability. 40 CFR 51.165(a)(2) is incorporated by reference. This Rule applies to areas designated as 

18 nonattainment in 40 CFR 81.334, including any subsequent amendments or editions. 

19 (d) This Rule is not applicable to: 

20 (1) complex sources of air pollution regulated only under Section .0800 of this Subchapter and not 

21 under any other rule in this Subchapter; 

22 (2) emission of pollutants at the new major stationary source or major modification located in the 

23 nonattainment area that are pollutants other than the pollutant or pollutants for which the area is 

24 nonattainment. (A major stationary source or major modification that is major for volatile organic 

25 compounds or nitrogen oxides is also major for ozone.); 

26 (3) emission of pollutants for which the source or modification is not major;

27 (4) a new source or modification that qualifies for exemption under the provision of 40 CFR 

28 51.165(a)(4); or 

29 (5) emission of compounds listed under 40 CFR 51.100(s) as having been determined to have 

30 negligible photochemical reactivity except carbon monoxide. 

31 (e) 15A NCAC 02Q .0102 and .0302 are not applicable to any source to which this Rule applies. The owner or 

32 operator of the source shall apply for and receive a permit as required in 15A NCAC 02Q .0300 or .0500. 

33 (f) To issue a permit to a source to which this Rule applies, the Director shall determine that the source meets the 

34 following requirements: 

35 (1) The new major stationary source or major modification will emit the nonattainment pollutant at a 

36 rate no more than the lowest achievable emission rate; 

A-18
II-9 

1 (2) The owner or operator of the proposed new major stationary source or major modification has 

2 demonstrated that all major stationary sources in the State that are owned or operated by this 

3 person (or any entity controlling, controlled by, or under common control with this person) are 

4 subject to emission limitations and are in compliance, or on a schedule for compliance that is 

5 federally enforceable or contained in a court decree, with all applicable emission limitations and 

6 standards of this Subchapter that EPA has authority to approve as elements of the North Carolina 

7 State Implementation Plan for Air Quality; 

8 (3) The owner or operator of the proposed new major stationary source or major modification will 

9 obtain sufficient emission reductions of the nonattainment pollutant from other sources in the 

10 nonattainment area so that the emissions from the new major source and associated new minor 

11 sources will be less than the emissions reductions by a ratio of at least 1.00 to 1.15 for volatile 

12 organic compounds and nitrogen oxides and by a ratio of less than one to one for carbon 

13 monoxide. The baseline for this emission offset shall be the actual emissions of the source from 

14 which offset credit is obtained. Emission reductions shall not include any reductions resulting 

15 from compliance (or scheduled compliance) with applicable rules in effect before the application. 

16 The difference between the emissions from the new major source and associated new minor 

17 sources of carbon monoxide and the emission reductions shall be sufficient to represent reasonable 

18 further progress toward attaining the National Ambient Air Quality Standards. The emissions 

19 reduction credits shall also conform to the provisions of 40 CFR 51.165(a)(3)(ii)(A) through (G) 

20 and (J); and 

21 (4) The North Carolina State Implementation Plan for Air Quality is being carried out for the 

22 nonattainment area in which the proposed source is located. 

23 (g) New natural gas-fired electrical utility generating units for which cost recovery is sought pursuant to G. S. 62-

24 133.6 shall install lowest achievable emission rate technology for NOX and SO2, regardless of the applicability of the 

25 rest of this Rule. 

26 (h) 40 CFR 51.165(f) is incorporated by reference except that 40 CFR 51.165(f)(10)(iv)(A) is changed to read: "If 

27 the emissions level calculated in accordance with Paragraph (f)(6) of this Section is equal to or greater than 80 

28 percent of the PAL level, the Director shall renew the PAL at the same level." 40 CFR 51.165(f)(10)(iv)(B) is not 

29 incorporated by reference.

30 (i) When a particular source or modification becomes a major stationary source or major modification solely by 

31 virtue of a relaxation in any enforceable limitation established after August 7, 1980, on the capacity of the source or 

32 modification to emit a pollutant, such as a restriction on hours of operation, then the provisions of this Rule shall 

33 apply to the source or modification as though construction had not yet begun on the source or modification. 

34 (j) To issue a permit to a source of a nonattainment pollutant, the Director shall determine, in accordance with 

35 Section 173(a)(5) of the Clean Air Act and in addition to the other requirements of this Rule, that an analysis 

36 (produced by the permit applicant) of alternative sites, sizes, production processes, and environmental control 

A-19
II-10

1 techniques for the source demonstrates that the benefits of the source significantly outweigh the environmental and 

2 social costs imposed as a result of its location, construction, or modification. 

3 (k) The provisions of 40 CFR 52.21(r)(2) regarding the period of validity of approval to construct are incorporated 

4 by reference except that the term "Administrator" is replaced with "Director". 

5 (l) Approval of an application regarding the requirements of this Rule does not relieve the owner or operator of the 

6 responsibility to comply with applicable provisions of other rules of this Chapter and any other requirements under 

7 local, state, or federal law. 

8 (m) Except as provided in 40 CFR 52.28(c)(6), for a source or modification subject to this Rule the following 

9 procedures shall be followed: 

10 (1) Notwithstanding any other provisions of this Paragraph, the Director shall, no later than 60 days 

11 after receipt of an application, notify the Federal Land Manager with the U.S. Department of 

12 Interior and U.S. Department of Agriculture of an application from a source or modification 

13 subject to this Rule; 

14 (2) The owner or operator of the source shall provide an analysis of the impairment to visibility that 

15 would occur because of the source or modification and general commercial, industrial and other 

16 growth associated with the source or modification; 

17 (3) When a source or modification may affect the visibility of a Class I area the Director shall provide 

18 written notification to all affected Federal Land Managers within 30 days of receiving the permit 

19 application or within 30 days of receiving advance notification of an application. The notification 

20 shall be at least 30 days before the publication of the notice for public comment on the application. 

21 The notification shall include a copy of all information relevant to the permit application including 

22 an analysis provided by the source of the potential impact of the proposed source on visibility; 

23 (4) The Director shall consider any analysis concerning visibility impairment performed by the 

24 Federal Land Manager if the analysis is received within 30 days of notification. If the Director 

25 finds that the analysis of the Federal Land Manager fails to demonstrate to his satisfaction that an 

26 adverse impact on visibility will result in the Class I area, the Director shall provide in the notice 

27 of public hearing on the application, an explanation of his decision or notice where the explanation 

28 can be obtained; 

29 (5) The Director shall issue permits only to those sources whose emissions will be consistent with 

30 making reasonable progress, as defined in Section 169A of the Clean Air Act, toward the national 

31 goal of preventing any future, and remedying any existing, impairment of visibility in mandatory 

32 Class I areas when the impairment results from manmade air pollution. In making the decision to 

33 issue a permit, the Director shall consider the cost of compliance, the time necessary for 

34 compliance, the energy and nonair quality environmental impacts of compliance, and the useful 

35 life of the source; and 

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II-11

1 (6) The Director may require monitoring of visibility in or around any Class I area by the proposed 

2 new source or modification when the visibility impact analysis indicates possible visibility 

3 impairment. 

4 The requirements of this Paragraph do not apply to nonprofit health or nonprofit educational institutions. 

5 (n) If the owner or operator of a source is using projected actual emissions to avoid applicability of nonattainment 

6 new source review, the owner or operator shall notify the director of the modification before beginning actual 

7 construction. The notification shall include: 

8 (1) a description of the project; 

9 (2) identification of sources whose emissions could be affected by the project; 

10 (3) the calculated projected actual emissions and an explanation of how the projected actual emissions 

11 were calculated, including identification of emissions excluded by 40 CFR 

12 51.165(a)(1)(xxviii)(B)(3); 

13 (4) the calculated baseline actual emissions and an explanation of how the baseline actual emissions 

14 were calculated; and 

15 (5) any netting calculations if applicable. 

16 If upon reviewing the notification, the Director finds that the project will cause a nonattainment new source review 

17 evaluation, then the Director shall notify the owner or operator of his findings. The owner or operator shall not make 

18 the modification until it has received a permit issued pursuant to this Rule. If a permit revision is not required 

19 pursuant to this Rule, the owner or operator shall maintain records of annual emissions in tons per year on a calendar 

20 year basis related to the modifications for 10 years following resumption of regular operations after the change if the 

21 project involves increasing the emissions unit's design capacity or its potential to emit the regulated NSR pollutant; 

22 otherwise these records shall be maintained for five years following resumption of regular operations after the 

23 change. The owner or operator shall submit a report to the director within 60 days after the end of each year during 

24 which these records must be generated. The report shall contain the items listed in 40 CFR 51.165(a)(6)(v)(A) 

25 through (C). The owner or operator shall make the information documented and maintained under this Paragraph 

26 available to the Director or the general public pursuant to the requirements in 40 CFR 70.4(b)(3)(viii). 

27 (o) The reference to the Code of Federal Regulations (CFR) in this Rule are incorporated by reference unless a 

28 specific reference states otherwise. Except for 40 CFR 81.334, the version of the CFR incorporated in this Rule is 

29 that as of May 16, 2008 and does not include any subsequent amendments or editions to the referenced material. 

30 

31 History Note: Authority G.S. 143-215.3(a)(1); 143-215.107(a)(5); 143-215.108(b); 

32 Eff. June 1, 1981; 

33 Amended Eff. December 1, 1993; December 1, 1992; August 1, 1991; December 1, 1989; October 

34 1, 1989; July 1, 1988; October 1, 1987; June 1, 1985; January 1, 1985; February 1, 1983; 

35 Temporary Amendment Eff. March 8, 1994 for a period of 180 days or until the permanent rule is 

36 effective, whichever is sooner; 

A-21
II-12

1 Amended Eff. ; January 2, 2011; September 1, 2010; May 1, 2008; May 1, 2005; July 1, 

2 1998; July 1, 1996; July 1, 1995; July 1, 1994. 

3

4

A-22
CHAPTER III 

REPORT OF PROCEEDINGS 

Introduction 

The Department of Environmental and Natural Resources, Division of Air Quality, held a public 

hearing on January 15, 2013 at 6:00pm in the Kannapolis, NC. 

The hearing considered the proposed amendment to Rules 15A NCAC 02D .0530, Prevention Of 

Significant Deterioration and 15A NCAC 02D .0531, Sources In Nonattainment Areas. 

 The proposed effective date for these rules is projected to be May 1, 2013. 

A public notice announcing this hearing was mailed to each person on the official mailing list for 

rule-making hearings. The public notice was also published in the North Carolina Register at 

least 15 days before the public hearing and in the Charlotte Observer, the Wilmington Star News, 

the Asheville Citizen Times, the Winston Salem Journal, and the Raleigh News and Observer at 

least 30 days prior to the public hearing. 

III-1 A-23



Transcript

A transcript of the January 15, 2013 hearing has not been prepared; however, an audio 

recording of the proceeding will be kept on file with the Division of Air Quality for one 

year from the date of the final actions by the Environmental Management Commission. 

A list of those attending the hearing as follows: 

Hearing Officer 

Mr. Benne C. Hutson, member of the Environmental Management Commission 

Staff Members 

 

Ms. Joelle Burleson, DAQ, DENR 

Mr. Glenn Sappie, DAQ, DENR 

Mr. Patrick Knowlson, DAQ, DENR 

Mr. Vladimir Zaytsev, DAQ, DENR 

Mr. Ron Slack, Mooresville Regional Office, DAQ, DENR 

Ms. Melinda Wolanin, Mooresville Regional Office, DAQ, DENR 

Ms. Denise Hayes, Mooresville Regional Office, DAQ, DENR 

Mr. Chuck Greco, Mecklenburg County Local Program 

Members of the General Public 

No members of the General Public appeared at the hearing. 

III-5 A-27
This page left intentionally blank. 

III-6 A-28
CHAPTER IV 

EXHIBITS 

EXHIBIT PAGE

Proposed Regulations as Published in the North Carolina Register and Presented at the 

Hearing

IV-2

Hearing Officer Comments at the Public Hearing IV-10

 

IV-1 A-29
PROPOSED RULES 

27:11 NORTH CAROLINA REGISTER DECEMBER 3, 2012 

1013

unopened original container that was filled by the product 

manufacturer. 

(c) Wine; On-premise. A person holding an on-premises wine 

permit may sell wine in the unopened original container, by the 

carafe, by the glass or a single-service and single-use container. 

A person holding an on-premises wine permit may sell wine 

mixed with non-alcoholic beverages by the carafe, by the glass 

or a single-service and single-use container. Wine served in 

carafes, by the glass or single-service and single-use containers 

may be dispensed under pressure from nitrogen from sealed bulk 

containers provided the containers and dispensing systems have 

been approved by the Commission and the State Commissioner 

of Health Services. 

The vintner, brand and type of wine dispensed by the carafe, 

glass or single-service and single-use container except for the 

house wine, shall appear on the wine list; and where the wine is 

dispensed from bulk containers, the vintner, brand and type shall 

be shown on the knobs of draught faucets. 

(d) Use of Siphons. The use of siphons or other types of 

dispensers is allowed if the malt beverage or wine contents are 

dispensed directly from the original containers. 

(e) Mixed Beverages. A person holding a mixed beverages 

permit may sell mixed beverages in a glass, in a pitcher or in a 

single-service and single-use container. 

(f) Multi-Use Containers. All multi-use containers used by 

permittees to serve any alcoholic beverages shall meet the 

requirements as referenced by FDA Food Code 2009, 3-

304.11(a). Multi-use containers include glassware, mugs, 

pitchers and carafes. 

Authority G.S. 18B-100; 18B-206; 18B-207; 130A-248(a); FDA 

Food Code 2009, 3-304.11(a). 

TITLE 15A – DEPARTMENT OF ENVIRONEMENT AND 

NATURAL RESOURCES 

Notice is hereby given in accordance with G.S. 150B-21.2 that 

the Environmental Management Commission intends to amend 

the rules cited as 15A NCAC 02D .0530-.0531. 

Agency obtained G.S. 150B-19.1 certification: 

 OSBM certified on: October 10, 2012

 RRC certified on:

 Not Required

Link to agency website pursuant to G.S. 150B-19.1(c): 

http://www.ncair.org//rules/hearing 

Proposed Effective Date: May 1, 2013 

Public Hearing: 

Date: January 15, 2013 

Time: 6:00 p.m. 

Location: Kannapolis Train Station, 201 South Main Street, 

Kannapolis, NC 28081 

Reason for Proposed Action: 15A NCAC 02D .0530 –

Prevention of Significant Deterioration, and 15A NCAC 02D 

.0531, Sources in Nonattainment Areas, to revise North 

Carolina's nitrogen oxides (NOx) significance level from 140 

tons per year (tpy) to 40 tpy. The Unites States Environmental 

Protection Agency (USEPA) determined that the state 

significance level for NOx for fine particulate matter (PM2.5) 

must be revised to reflect the federal 40 tpy significance level in 

the federal implementation rule. 

15A NCAC 02D .0530 is also proposed to be amended to update 

the federal cross-reference to incorporate the new 24 hour and 

annual PM2.5 increments as promulgated on October 20, 2010 

(75 FR 64864). 

Procedure by which a person can object to the agency on a 

proposed rule: If you have any objections to the proposed rule, 

please mail a letter including your specific reasons to: Ms. 

Joelle Burleson, Division of Air Quality, 1641 Mail Service 

Center, Raleigh, NC 27699-1641

Comments may be submitted to: Joelle Burleson, Division of 

Air Quality, 1641 Mail Service Center, Raleigh, NC 27699-

1641, phone (919)707-8720, fax (919)707-8720, email 

joelle.burleson@ncdenr.gov. 

Comment period ends: February 1, 2013 

Procedure for Subjecting a Proposed Rule to Legislative 

Review: If an objection is not resolved prior to the adoption of 

the rule, a person may also submit written objections to the 

Rules Review Commission after the adoption of the Rule. If the 

Rules Review Commission receives written and signed 

objections after the adoption of the Rule in accordance with G.S. 

150B-21.3(b2) from 10 or more persons clearly requesting 

review by the legislature and the Rules Review Commission 

approves the rule, the rule will become effective as provided in 

G.S. 150B-21.3(b1). The Commission will receive written 

objections until 5:00 p.m. on the day following the day the 

Commission approves the rule. The Commission will receive 

those objections by mail, delivery service, hand delivery, or 

facsimile transmission. If you have any further questions 

concerning the submission of objections to the Commission, 

please call a Commission staff attorney at 919-431-3000. 

Fiscal impact (check all that apply). 

State funds affected

Environmental permitting of DOT affected

 Analysis submitted to Board of Transportation 

Local funds affected

 Date submitted to OSBM: 

Substantial economic impact (≥$500,000)

Approved by OSBM

No fiscal note required by G.S. 150B-21.4

CHAPTER 02 - ENVIRONMENTAL MANAGEMENT 

SUBCHAPTER 02D - AIR POLLUTION CONTROL 

REQUIREMENTS 

IV-2 A-30
PROPOSED RULES 

27:11 NORTH CAROLINA REGISTER DECEMBER 3, 2012 

1014

SECTION .0500 – EMISSION CONTROL STANDARDS 

15A NCAC 02D .0530 PREVENTION OF SIGNIFICANT 

DETERIORATION 

(a) The purpose of the Rule is to implement a program for the 

prevention of significant deterioration of air quality as required 

by 40 CFR 51.166. 

(b) For the purposes of this Rule the definitions contained in 40 

CFR 51.166(b) and 40 CFR 51.301 apply except the definition 

of "baseline actual emissions." For the purposes of this Rule: 

(1) "Baseline actual emissions" means the rate of 

emissions, in tons per year, of a regulated new 

source review (NSR) pollutant, as determined 

in accordance with Parts (A) through (C) of 

this Subparagraph: 

(A) For an existing emissions unit, 

baseline actual emissions means the 

average rate, in tons per year, at 

which the emissions unit actually 

emitted the pollutant during any 

consecutive 24-month period selected 

by the owner or operator within the 5-

year period immediately preceding 

the date that a complete permit 

application is received by the 

Division for a permit required under 

this Rule. The Director shall allow a 

different time period, not to exceed 

10 years immediately preceding the 

date that a complete permit 

application is received by the 

Division, if the owner or operator 

demonstrates that it is more 

representative of normal source 

operation. For the purpose of 

determining baseline actual 

emissions, the following apply: 

(i) The average rate shall 

include fugitive emissions to 

the extent quantifiable, and 

emissions associated with 

startups, shutdowns, and 

malfunctions; 

(ii) The average rate shall be 

adjusted downward to 

exclude any non-compliant 

emissions that occurred 

while the source was 

operating above any 

emission limitation that was 

legally enforceable during 

the consecutive 24-month 

period; 

(iii) For an existing emission unit 

(other than an electric utility 

steam generating unit), the 

average rate shall be 

adjusted downward to 

exclude any emissions that 

would have exceeded an 

emission limitation with 

which the major stationary 

source must currently 

comply. However, if the 

State has taken credit in an 

attainment demonstration or 

maintenance plan consistent 

with the requirements of 40 

CFR 51.165(a)(3)(ii)(G) for 

an emission limitation that is 

part of a maximum 

achievable control 

technology standard that the 

Administrator proposed or 

promulgated under part 63 

of the Code of Federal 

Regulations, the baseline 

actual emissions shall be 

adjusted to account for such 

emission reductions; 

(iv) For an electric utility steam 

generating unit, the average 

rate shall be adjusted 

downward to reflect any 

emissions reductions under 

G.S. 143-215.107D and for 

which cost recovery is 

sought pursuant to G.S. 62-

133.6; 

(v) For a regulated NSR 

pollutant, when a project 

involves multiple emissions 

units, only one consecutive 

24-month period shall be 

used to determine the 

baseline actual emissions for 

all the emissions units being 

changed. A different 

consecutive 24-month period 

for each regulated NSR 

pollutant can be used for 

each regulated NSR 

pollutant; and 

(vi) The average rate shall not be 

based on any consecutive 

24-month period for which 

there is inadequate 

information for determining 

annual emissions, in tons per 

year, and for adjusting this 

amount if required by 

Subparts (ii) and (iii) of this 

Part; 

(B) For a new emissions unit, the baseline 

actual emissions for purposes of 

determining the emissions increase 

that will result from the initial 

construction and operation of such 

IV-3 A-31
PROPOSED RULES 

27:11 NORTH CAROLINA REGISTER DECEMBER 3, 2012 

1015

unit shall equal zero; and thereafter, 

for all other purposes, shall equal the 

unit's potential to emit; and 

(C) For a plantwide applicability limit 

(PAL) for a stationary source, the 

baseline actual emissions shall be 

calculated for existing emissions units 

in accordance with the procedures 

contained in Part (A) of this 

Subparagraph, and for a new 

emissions unit in accordance with the 

procedures contained in Part (B) of 

this Subparagraph; 

(2) In the definition of "net emissions increase," 

the reasonable period specified in 40 CFR 

51.166(b)(3)(ii) is seven years; 

(3) The limitation specified in 40 CFR 

51.166(b)(15)(ii) does not apply; and 

(4) Particulate matter PM2.5 significant levels in 

40 CFR 51.166(b)(23)(i) are incorporated by 

reference except as otherwise provided in this 

Rule. Sulfur dioxide and nitrogen oxides are 

precursor to PM2.5 in all attainment and 

unclassifiable areas. Volatile organic 

compounds and ammonia are not significant 

precursors to PM2.5. 

(c) All areas of the State are classified as Class II except that the 

following areas are Class I: 

(1) Great Smoky Mountains National Park; 

(2) Joyce Kilmer Slickrock National Wilderness 

Area; 

(3) Linville Gorge National Wilderness Area; 

(4) Shining Rock National Wilderness Area; and 

(5) Swanquarter National Wilderness Area. 

(d) Redesignations of areas to Class I or II may be submitted as 

state proposals to the Administrator of the Environmental 

Protection Agency (EPA), if the requirements of 40 CFR 

51.166(g)(2) are met. Areas may be proposed to be redesignated 

as Class III, if the requirements of 40 CFR 51.166(g)(3) are met. 

Redesignations may not, however, be proposed which would 

violate the restrictions of 40 CFR 51.166(e). Lands within the 

boundaries of Indian Reservations may be redesignated only by 

the appropriate Indian Governing Body. 

(e) In areas designated as Class I, II, or III, increases in 

pollutant concentration over the baseline concentration shall be 

limited to the values set forth in 40 CFR 51.166(c). However, 

concentration of the pollutant shall not exceed standards set forth 

in 40 CFR 51.166(d). 

(f) Concentrations attributable to the conditions described in 40 

CFR 51.166(f)(1) shall be excluded in determining compliance 

with a maximum allowable increase. However, the exclusions 

referred to in 40 CFR 51.166(f)(1)(i) or (ii) shall be limited to 

five years as described in 40 CFR 51.166(f)(2). 

(g) Major stationary sources and major modifications shall 

comply with the requirements contained in 40 CFR 51.166(i) 

and (a)(7) and by extension in 40 CFR 51.166(j) through (o) and 

(w). The transition provisions allowed by 40 CFR 52.21 

(i)(11)(i) and (ii) and (m)(1)(vii) and (viii) are hereby adopted 

under this Rule. The minimum requirements described in the 

portions of 40 CFR 51.166 referenced in this Paragraph are 

hereby adopted as the requirements to be used under this Rule, 

except as otherwise provided in this Rule. Wherever the 

language of the portions of 40 CFR 51.166 referenced in this 

Paragraph speaks of the "plan," the requirements described 

therein shall apply to the source to which they pertain, except as 

otherwise provided in this Rule. Whenever the portions of 40 

CFR 51.166 referenced in this Paragraph provide that the State 

plan may exempt or not apply certain requirements in certain 

circumstances, those exemptions and provisions of 

nonapplicability are also hereby adopted under this Rule. 

However, this provision shall not be interpreted so as to limit 

information that may be requested from the owner or operator by 

the Director as specified in 40 CFR 51.166(n)(2). 

(h) New natural gas-fired electrical utility generating units for 

which cost recovery is sought pursuant to G. S. 62-133.6 shall 

install best available control technology for NOX and SO2, 

regardless of applicability of the rest of this Rule. 

(i) 40 CFR 51.166(w)(10)(iv)(a) is changed to read: "If the 

emissions level calculated in accordance with Paragraph (w)(6) 

of this Section is equal to or greater than 80 percent of the PAL 

[plant wide applicability limit] level, the Director shall renew the 

PAL at the same level." 40 CFR 51.166(w)(10)(iv)(b) is not 

incorporated by reference. 

(j) 15A NCAC 02Q .0102 and .0302 are not applicable to any 

source to which this Rule applies. The owner or operator of the 

sources to which this Rule applies shall apply for and receive a 

permit as required in 15A NCAC 02Q .0300 or .0500. 

(k) When a particular source or modification becomes a major 

stationary source or major modification solely by virtue of a 

relaxation in any enforceable limitation which was established 

after August 7, 1980, on the capacity of the source or 

modification to emit a pollutant, such as a restriction on hours of 

operation, then the provisions of this Rule shall apply to the 

source or modification as though construction had not yet begun 

on the source or modification. 

(l) The provisions of 40 CFR 52.21(r)(2) regarding the period of 

validity of approval to construct are incorporated by reference 

except that the term "Administrator" is replaced with "Director". 

(m) Volatile organic compounds exempted from coverage in 40 

CFR 51.100(s) shall be exempted when calculating source 

applicability and control requirements under this Rule. 

(n) The degree of emission limitation required for control of any 

air pollutant under this Rule shall not be affected by: 

(1) that amount of a stack height, not in existence 

before December 31, 1970, that exceeds good 

engineering practice; or 

(2) any other dispersion technique not 

implemented before then. 

(o) A substitution or modification of a model as provided for in 

40 CFR 51.166(l) is subject to public comment procedures in 

accordance with the requirements of 40 CFR 51.102. 

(p) Permits may be issued on the basis of innovative control 

technology as set forth in 40 CFR 51.166(s)(1) if the 

requirements of 40 CFR 51.166(s)(2) have been met, subject to 

the condition of 40 CFR 51.166(s)(3), and with the allowance set 

forth in 40 CFR 51.166(s)(4). 

(q) If a source to which this Rule applies impacts an area 

designated Class I by requirements of 40 CFR 51.166(e), notice 

IV-4 A-32
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27:11 NORTH CAROLINA REGISTER DECEMBER 3, 2012 

1016

to EPA shall be provided as set forth in 40 CFR 51.166(p)(1). If 

the Federal Land Manager presents a demonstration described in 

40 CFR 51.166(p)(3) during the public comment period or 

public hearing to the Director and if the Director concurs with 

this demonstration, the permit application shall be denied. 

Permits may be issued on the basis that the requirements for 

variances as set forth in 40 CFR 51.166(p)(4), (p)(5) and (p)(7), 

or (p)(6) and (p)(7) have been satisfied. 

(r) A permit application subject to this Rule shall be processed 

in accordance with the procedures and requirements of 40 CFR 

51.166(q). Within 30 days of receipt of the application, 

applicants shall be notified if the application is complete as to 

initial information submitted. Commencement of construction 

before full prevention of significant deterioration approval is 

obtained constitutes a violation of this Rule. 

(s) Approval of an application with regard to the requirements 

of this Rule does not relieve the owner or operator of the 

responsibility to comply with applicable provisions of other 

rules of this Subchapter or Subchapter 02Q of this Title and any 

other requirements under local, state, or federal law. 

(t) When a source or modification is subject to this Rule the 

following procedures apply: 

(1) Notwithstanding any other provisions of this 

Paragraph, the Director shall, no later than 60 

days after receipt of an application, notify the 

Federal Land Manager with the U.S. 

Department of Interior and U.S. Department of 

Agriculture of an application from a source or 

modification subject to this Rule; 

(2) When a source or modification may affect 

visibility of a Class I area the Director shall 

provide written notification to all affected 

Federal Land Managers within 30 days of 

receiving the permit application or within 30 

days of receiving advance notification of an 

application. The notification shall be at least 

30 days prior to the publication of notice for 

public comment on the application. The 

notification shall include a copy of all 

information relevant to the permit application 

including an analysis provided by the source 

of the potential impact of the proposed source 

on visibility; 

(3) The Director shall consider any analysis 

concerning visibility impairment performed by 

the Federal Land Manager if the analysis is 

received within 30 days of notification. If the 

Director finds that the analysis of the Federal 

Land Manager fails to demonstrate to his 

satisfaction that an adverse impact on visibility 

will result in the Class I area, the Director shall 

provide in the notice of public hearing on the 

application, an explanation of his decision or 

notice as to where the explanation can be 

obtained; and 

(4) The Director may require monitoring of 

visibility in or around any Class I area by the 

proposed new source or modification when the 

visibility impact analysis indicates possible 

visibility impairment. 

(u) If the owner or operator of a source is using projected actual 

emissions to avoid applicability of prevention of significant 

deterioration requirements, the owner or operator shall notify the 

Director of the modification before beginning actual 

construction. The notification shall include: 

(1) a description of the project; 

(2) identification of sources whose emissions 

could be affected by the project; 

(3) the calculated projected actual emissions and 

an explanation of how the projected actual 

emissions were calculated, including 

identification of emissions excluded by 40 

CFR 51.166(b)(40)(ii)(c); 

(4) the calculated baseline actual emissions and an 

explanation of how the baseline actual 

emissions were calculated; and 

(5) any netting calculations if applicable. 

If upon reviewing the notification, the Director finds that the 

project will cause a prevention of significant deterioration 

evaluation, then the Director shall notify the owner or operator 

of his findings. The owner or operator shall not make the 

modification until it has received a permit issued pursuant to this 

Rule. If a permit revision is not required pursuant to this rule, the 

owner or operator shall maintain records of annual emissions in 

tons per year, on a calendar year basis related to the 

modifications for 10 years following resumption of regular 

operations after the change if the project involves increasing the 

emissions unit's design capacity or its potential to emit the 

regulated NSR pollutant; otherwise these records shall be 

maintained for five years following resumption of regular 

operations after the change. The owner or operator shall submit a 

report to the director within 60 days after the end of each year 

during which these records must be generated. The report shall 

contain the items listed in 40 CFR 51.166(r)(6)(v)(a) through (c). 

The owner or operator shall make the information documented 

and maintained under this Paragraph available to the Director or 

the general public pursuant to the requirements in 40 CFR 

70.4(b)(3)(viii). 

(v) The references to the Code of Federal Regulations (CFR) in 

this Rule are incorporated by reference unless a specific 

reference states otherwise. The version of the CFR incorporated 

in this Rule is that as of October 20, 2010 at 

http://www.gpo.gov/fdsys/pkg/FR-2010-10-20/pdf/2010-

25132.pdf and does not include any subsequent amendments or 

editions to the referenced material. 

Authority G.S. 143-215.3(a)(1); 143-215.107(a)(3); 143-

215.107(a)(5); 143-215.107(a)(7); 143-215.108(b); 150B-21.6. 

15A NCAC 02D .0531 SOURCES IN 

NONATTAINMENT AREAS 

(a) For the purpose of this Rule the definitions contained in 40 

CFR 51.165(a)(1) and 40 CFR 51.301 apply except the 

definition of "baseline actual emissions." For the purposes of 

this Rule: 

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27:11 NORTH CAROLINA REGISTER DECEMBER 3, 2012 

1017

(1) "Baseline actual emissions" means the rate of 

emissions, in tons per year, of a regulated new 

source review (NSR) pollutant, as determined 

in accordance with Parts (A) through (C) of 

this Subparagraph: 

(A) For an existing emissions unit, 

baseline actual emissions means the 

average rate, in tons per year, at 

which the emissions unit actually 

emitted the pollutant during any 

consecutive 24-month period selected 

by the owner or operator within the 5-

year period immediately preceding 

the date that a complete permit 

application is received by the 

Division for a permit required under 

this Rule. The Director shall allow a 

different time period, not to exceed 

10 years immediately preceding the 

date that a complete permit 

application is received by the 

Division, if the owner or operator 

demonstrates that it is more 

representative of normal source 

operation. For the purpose of 

determining baseline actual 

emissions, the following apply: 

(i) The average rate shall 

include fugitive emissions to 

the extent quantifiable, and 

emissions associated with 

startups, shutdowns, and 

malfunctions; 

(ii) The average rate shall be 

adjusted downward to 

exclude any non-compliant 

emissions that occurred 

while the source was 

operating above any 

emission limitation that was 

legally enforceable during 

the consecutive 24-month 

period; 

(iii) For an existing emission unit 

(other than an electric utility 

steam generating unit), the 

average rate shall be 

adjusted downward to 

exclude any emissions that 

would have exceeded an 

emission limitation with 

which the major stationary 

source must currently 

comply. However, if the 

State has taken credit in an 

attainment demonstration or 

maintenance plan consistent 

with the requirements of 40 

CFR 51.165(a)(3)(ii)(G) for 

an emission limitation that is 

part of a maximum 

achievable control 

technology standard that the 

Administrator proposed or 

promulgated under part 63 

of the Code of Federal 

Regulations, the baseline 

actual emissions shall be 

adjusted to account for such 

emission reductions; 

(iv) For an electric utility steam 

generating unit, the average 

rate shall be adjusted 

downward to reflect any 

emissions reductions under 

G.S. 143-215.107D and for 

which cost recovery is 

sought pursuant to G.S. 62-

133.6; 

(v) For a regulated NSR 

pollutant, when a project 

involves multiple emissions 

units, only one consecutive 

24-month period shall be 

used to determine the 

baseline actual emissions for 

all the emissions units being 

changed. A different 

consecutive 24-month period 

for each regulated NSR 

pollutant; and 

(vi) The average rate shall not be 

based on any consecutive 

24-month period for which 

there is inadequate 

information for determining 

annual emissions, in tons per 

year, and for adjusting this 

amount if required by 

Subparts (ii) and (iii) of this 

Part; 

(B) For a new emissions unit, the baseline 

actual emissions for purposes of 

determining the emissions increase 

that will result from the initial 

construction and operation of such 

unit shall equal zero; and thereafter, 

for all other purposes, shall equal the 

unit's potential to emit; and 

(C) For a plantwide applicability limit 

(PAL) for a stationary source, the 

baseline actual emissions shall be 

calculated for existing emissions units 

in accordance with the procedures 

contained in Part (A) of this 

Subparagraph, and for a new 

emissions unit in accordance with the 

IV-6 A-34
PROPOSED RULES 

27:11 NORTH CAROLINA REGISTER DECEMBER 3, 2012 

1018

procedures contained in Part (B) of 

this Subparagraph; 

(2) In the definition of "net emissions increase," 

the reasonable period specified in 40 CFR 

51.165(a)(1)(vi)(C)(1) is seven years; and 

(3) Particulate matter PM2.5 significant levels in 

40 CFR 51.165(a)(1)(x)(A) are incorporated 

by reference except as otherwise provided in 

this Rule. Sulfur dioxide and nitrogen oxides 

are precursor to PM2.5 in all nonattainment 

areas. Volatile organic compounds and 

ammonia are not significant precursors to 

PM2.5. 

(b) Redesignation to Attainment. If any county or part of a 

county to which this Rule applies is later designated in 40 CFR 

81.334 as attainment, all sources in that county subject to this 

Rule before the redesignation date shall continue to comply with 

this Rule. 

(c) Applicability. 40 CFR 51.165(a)(2) is incorporated by 

reference. This Rule applies to areas designated as 

nonattainment in 40 CFR 81.334, including any subsequent 

amendments or editions. 

(d) This Rule is not applicable to: 

(1) complex sources of air pollution regulated 

only under Section .0800 of this Subchapter 

and not under any other rule in this 

Subchapter; 

(2) emission of pollutants at the new major 

stationary source or major modification 

located in the nonattainment area that are 

pollutants other than the pollutant or pollutants 

for which the area is nonattainment. (A major 

stationary source or major modification that is 

major for volatile organic compounds or 

nitrogen oxides is also major for ozone.); 

(3) emission of pollutants for which the source or 

modification is not major; 

(4) a new source or modification that qualifies for 

exemption under the provision of 40 CFR 

51.165(a)(4); or 

(5) emission of compounds listed under 40 CFR 

51.100(s) as having been determined to have 

negligible photochemical reactivity except 

carbon monoxide. 

(e) 15A NCAC 02Q .0102 and .0302 are not applicable to any 

source to which this Rule applies. The owner or operator of the 

source shall apply for and receive a permit as required in 15A 

NCAC 02Q .0300 or .0500. 

(f) To issue a permit to a source to which this Rule applies, the 

Director shall determine that the source meets the following 

requirements: 

(1) The new major stationary source or major 

modification will emit the nonattainment 

pollutant at a rate no more than the lowest 

achievable emission rate; 

(2) The owner or operator of the proposed new 

major stationary source or major modification 

has demonstrated that all major stationary 

sources in the State that are owned or operated 

by this person (or any entity controlling, 

controlled by, or under common control with 

this person) are subject to emission limitations 

and are in compliance, or on a schedule for 

compliance that is federally enforceable or 

contained in a court decree, with all applicable 

emission limitations and standards of this 

Subchapter that EPA has authority to approve 

as elements of the North Carolina State 

Implementation Plan for Air Quality;

(3) The owner or operator of the proposed new 

major stationary source or major modification 

will obtain sufficient emission reductions of 

the nonattainment pollutant from other sources 

in the nonattainment area so that the emissions 

from the new major source and associated new 

minor sources will be less than the emissions 

reductions by a ratio of at least 1.00 to 1.15 for 

volatile organic compounds and nitrogen 

oxides and by a ratio of less than one to one 

for carbon monoxide. The baseline for this 

emission offset shall be the actual emissions of 

the source from which offset credit is obtained. 

Emission reductions shall not include any 

reductions resulting from compliance (or 

scheduled compliance) with applicable rules in 

effect before the application. The difference 

between the emissions from the new major 

source and associated new minor sources of 

carbon monoxide and the emission reductions 

shall be sufficient to represent reasonable 

further progress toward attaining the National 

Ambient Air Quality Standards. The 

emissions reduction credits shall also conform 

to the provisions of 40 CFR 

51.165(a)(3)(ii)(A) through (G) and (J); and 

(4) The North Carolina State Implementation Plan 

for Air Quality is being carried out for the 

nonattainment area in which the proposed 

source is located. 

(g) New natural gas-fired electrical utility generating units for 

which cost recovery is sought pursuant to G. S. 62-133.6 shall 

install lowest achievable emission rate technology for NOX and 

SO2, regardless of the applicability of the rest of this Rule. 

(h) 40 CFR 51.165(f) is incorporated by reference except that 

40 CFR 51.165(f)(10)(iv)(A) is changed to read: "If the 

emissions level calculated in accordance with Paragraph (f)(6) of 

this Section is equal to or greater than 80 percent of the PAL 

level, the Director shall renew the PAL at the same level." 40 

CFR 51.165(f)(10)(iv)(B) is not incorporated by reference. 

(i) When a particular source or modification becomes a major 

stationary source or major modification solely by virtue of a 

relaxation in any enforceable limitation established after 

August 7, 1980, on the capacity of the source or modification to 

emit a pollutant, such as a restriction on hours of operation, then 

the provisions of this Rule shall apply to the source or 

modification as though construction had not yet begun on the 

source or modification. 

IV-7 A-35
PROPOSED RULES 

27:11 NORTH CAROLINA REGISTER DECEMBER 3, 2012 

1019

(j) To issue a permit to a source of a nonattainment pollutant, 

the Director shall determine, in accordance with Section 

173(a)(5) of the Clean Air Act and in addition to the other 

requirements of this Rule, that an analysis (produced by the 

permit applicant) of alternative sites, sizes, production processes, 

and environmental control techniques for the source 

demonstrates that the benefits of the source significantly 

outweigh the environmental and social costs imposed as a result 

of its location, construction, or modification. 

(k) The provisions of 40 CFR 52.21(r)(2) regarding the period 

of validity of approval to construct are incorporated by reference 

except that the term "Administrator" is replaced with "Director". 

(l) Approval of an application regarding the requirements of this 

Rule does not relieve the owner or operator of the responsibility 

to comply with applicable provisions of other rules of this 

Chapter and any other requirements under local, state, or federal 

law. 

(m) Except as provided in 40 CFR 52.28(c)(6), for a source or 

modification subject to this Rule the following procedures shall 

be followed: 

(1) Notwithstanding any other provisions of this 

Paragraph, the Director shall, no later than 60 

days after receipt of an application, notify the 

Federal Land Manager with the U.S. 

Department of Interior and U.S. Department of 

Agriculture of an application from a source or 

modification subject to this Rule; 

(2) The owner or operator of the source shall 

provide an analysis of the impairment to 

visibility that would occur because of the 

source or modification and general 

commercial, industrial and other growth 

associated with the source or modification; 

(3) When a source or modification may affect the 

visibility of a Class I area the Director shall 

provide written notification to all affected 

Federal Land Managers within 30 days of 

receiving the permit application or within 30 

days of receiving advance notification of an 

application. The notification shall be at least 

30 days before the publication of the notice for 

public comment on the application. The 

notification shall include a copy of all 

information relevant to the permit application 

including an analysis provided by the source 

of the potential impact of the proposed source 

on visibility; 

(4) The Director shall consider any analysis 

concerning visibility impairment performed by 

the Federal Land Manager if the analysis is 

received within 30 days of notification. If the 

Director finds that the analysis of the Federal 

Land Manager fails to demonstrate to his 

satisfaction that an adverse impact on visibility 

will result in the Class I area, the Director shall 

provide in the notice of public hearing on the 

application, an explanation of his decision or 

notice where the explanation can be obtained; 

(5) The Director shall issue permits only to those 

sources whose emissions will be consistent 

with making reasonable progress, as defined in 

Section 169A of the Clean Air Act, toward the 

national goal of preventing any future, and 

remedying any existing, impairment of 

visibility in mandatory Class I areas when the 

impairment results from manmade air 

pollution. In making the decision to issue a 

permit, the Director shall consider the cost of 

compliance, the time necessary for 

compliance, the energy and nonair quality 

environmental impacts of compliance, and the 

useful life of the source; and 

(6) The Director may require monitoring of 

visibility in or around any Class I area by the 

proposed new source or modification when the 

visibility impact analysis indicates possible 

visibility impairment. 

The requirements of this Paragraph do not apply to nonprofit 

health or nonprofit educational institutions. 

(n) If the owner or operator of a source is using projected actual 

emissions to avoid applicability of nonattainment new source 

review, the owner or operator shall notify the director of the 

modification before beginning actual construction. The 

notification shall include: 

(1) a description of the project; 

(2) identification of sources whose emissions 

could be affected by the project; 

(3) the calculated projected actual emissions and 

an explanation of how the projected actual 

emissions were calculated, including 

identification of emissions excluded by 40 

CFR 51.165(a)(1)(xxviii)(B)(3); 

(4) the calculated baseline actual emissions and an 

explanation of how the baseline actual 

emissions were calculated; and 

(5) any netting calculations if applicable. 

If upon reviewing the notification, the Director finds that the 

project will cause a nonattainment new source review 

evaluation, then the Director shall notify the owner or operator 

of his findings. The owner or operator shall not make the 

modification until it has received a permit issued pursuant to this 

Rule. If a permit revision is not required pursuant to this Rule, 

the owner or operator shall maintain records of annual emissions 

in tons per year on a calendar year basis related to the 

modifications for 10 years following resumption of regular 

operations after the change if the project involves increasing the 

emissions unit's design capacity or its potential to emit the 

regulated NSR pollutant; otherwise these records shall be 

maintained for five years following resumption of regular 

operations after the change. The owner or operator shall submit a 

report to the director within 60 days after the end of each year 

during which these records must be generated. The report shall 

contain the items listed in 40 CFR 51.165(a)(6)(v)(A) through 

(C). The owner or operator shall make the information 

documented and maintained under this Paragraph available to 

the Director or the general public pursuant to the requirements in 

40 CFR 70.4(b)(3)(viii). 

IV-8 A-36
PROPOSED RULES 

27:11 NORTH CAROLINA REGISTER DECEMBER 3, 2012 

1020

(o) The reference to the Code of Federal Regulations (CFR) in 

this Rule are incorporated by reference unless a specific 

reference states otherwise. Except for 40 CFR 81.334, the 

version of the CFR incorporated in this Rule is that as of May 

16, 2008 and does not include any subsequent amendments or 

editions to the referenced material. 

Authority G.S. 143-215.3(a)(1); 143-215.107(a)(5); 143-

215.108(b). 

* * * * * * * * * * * * * * * * * * * 

Notice is hereby given in accordance with G.S. 150B-21.2 that 

the Environmental Management Commission intends to amend 

the rules cited as 15A NCAC 02D .0902,-.0903, .0909, .0951, 

.0961-.0962; 02Q .0102. 

Agency obtained G.S. 150B-19.1 certification: 

 OSBM certified on: November 5, 2012

 RRC certified on:

 Not Required

Link to agency website pursuant to G.S. 150B-19.1(c): 

http://www.ncair.org/rules/hearing/ 

Proposed Effective Date: May 1, 2013 

Public Hearing: 

Date: January 15, 2013 

Time: 6:00 p.m. 

Location: Kannapolis Train Station, 201 South Main Street, 

Kannapolis, NC 28081 

Reason for Proposed Action: 

The proposed amendments are in response to United States 

Environmental Protection Agency (USEPA) comments on North 

Carolina’s redesignation demonstration and maintenance plan 

for the North Carolina portion of the Charlotte-Gastonia, NCRock Hill, SC 1997 8-hour Ozone National Ambient Air Quality 

Standard (NAAQS) Nonattainment Area. USEPA identified the 

need for adjustment of applicability of the state’s Reasonably

Available Control Technology (RACT) rules to meet the 

requirements of Section 182(b)(2) of the Clean Air Act which 

requires RACT for all sources addressed by Control Technique 

Guidelines (CTGs) in nonattainment areas classified moderate 

and above. The current RACT rules’ applicability is structured 

such that the RACT requirement for sources in CTG categories 

applies to major sources with 100 tons of volatile organic 

compounds or more per year. Amendments to printing related 

and industrial solvent cleaning RACT rules are in response to 

industry associations’ requests for language clarifications and 

flexibilities consistent with the CTGs on which they are based. 

15A NCAC 02D .0902 - Applicability, to reflect applicability to 

all sources in a CTG category in order to meet the Clean Air Act 

requirement and thus facilitate the redesignation process and 

include provisions allowing for the shift of requirements to 

contingency measures upon redesignation of the area consistent 

with EPA procedures. 

15A NCAC 02D .0909 - Compliance Schedules For Sources In 

Ozone Nonattainment And Maintenance Areas, to update the 

compliance schedule corresponding to the adjustment in 

applicability. 

15A NCAC 02D .0951 - RACT For Sources of Volatile Organic 

Compounds, to provide flexibility to comply via the category 

specific rules in the Section or through approved site specific 

alternative determinations. 

15A NCAC 02D .0961 - Offset Lithographic Printing and 

Letterpress Printing, in response to industry associations’ 

comments and requests for language clarification and 

flexibilities consistent with the CTGs on which it is based 

including an equivalent rolling, consecutive 12 month 

applicability threshold consistent with the CTG to provide some 

relief from a recordkeeping standpoint, clarifying language, and 

addition of some specificity with respect to recordkeeping. 

15A NCAC 18A 02D .0962 - Industrial Cleaning Solvents, in 

response to industry associations’ comments and requests for 

language clarification and flexibilities consistent with the CTGs 

on which it is are based including an alternate VOC content 

level and compliance options for industrial solvents used for 

cleaning resins, inks, and coatings manufacturing equipment 

consistent with the CTG recommendations.

15A NCAC 02D .0903 - Recordkeeping: Reporting: Monitoring, 

to update cross-references. 

15A NCAC 02Q .0102 - Exemptions, to update cross-references. 

Procedure by which a person can object to the agency on a 

proposed rule: If you have any objections to the proposed 

rules, please mail a letter including your specific reasons to: Ms. 

Joelle Burleson, Division of Air Quality, 1641 Mail Service 

Center, Raleigh, NC 27699-1641.

Comments may be submitted to: Joelle Burleson, Division of 

Air Quality, 1641 Mail Service Center, Raleigh, NC 27699-

1641, phone (919)707-8720, fax (919)707-8720, email 

joelle.burleson@ncdenr.gov. 

Comment period ends: February 1, 2013 

Procedure for Subjecting a Proposed Rule to Legislative 

Review: If an objection is not resolved prior to the adoption of 

the rule, a person may also submit written objections to the 

Rules Review Commission after the adoption of the Rule. If the 

Rules Review Commission receives written and signed 

objections after the adoption of the Rule in accordance with G.S. 

150B-21.3(b2) from 10 or more persons clearly requesting 

review by the legislature and the Rules Review Commission 

approves the rule, the rule will become effective as provided in 

G.S. 150B-21.3(b1). The Commission will receive written 

objections until 5:00 p.m. on the day following the day the 

Commission approves the rule. The Commission will receive 

those objections by mail, delivery service, hand delivery, or 

facsimile transmission. If you have any further questions 

concerning the submission of objections to the Commission, 

please call a Commission staff attorney at 919-431-3000. 

Fiscal impact (check all that apply). 

State funds affected

Environmental permitting of DOT affected

IV-9 A-37
1

Hearing Officer's Suggested Hearing Comments 

INTRODUCTION

[Hearing officer]: 

 Good evening ladies and gentlemen. My name is Benne Hutson. I am a member of the North 

Carolina Environmental Management Commission. My role as hearing officer is to listen to all 

relevant comment on these proceedings and report them to the full commission. Sitting with me 

is Ms. Joelle Burleson. She is with the North Carolina Division of Air Quality, Planning Section. 

 Some of the staff from the Division of Air Quality are here to assist. Ms. Burleson, please 

introduce the staff present. 

[Ms. Burleson] (Introduces staff) 

[Hearing officer]: 

 This evening we are conducting three public hearings. During Hearing 1, we will take 

comments concerning amendments to several volatile organic compound (VOC) reasonably 

available control technology (RACT) rules. During Hearing 2, we will take comment on 

amendments to two rules that are part of the North Carolina's New Source Review (NSR) permit 

program. During Hearing 3, we will take comment on an amendment to the Division of Air 

Quality’s permit exemption rule. Fiscal notes have been written for all of the rule amendments 

presented in the hearings tonight and were approved and certified by the Office of State Budget 

and Management. These hearings will be held according to the North Carolina Administrative 

Procedures Act. The public notice for these hearings has been advertised in the North Carolina 

Register and five newspapers in the state. Copies of the notice have been sent to those on the 

official DAQ mailing list. I will enter the public notice, the proposed amendments and the fiscal 

notes into the hearing record without reading them at this time. 

IV-10 A-38
2

 It would be helpful if any person desiring to comment also submit a written statement for 

inclusion into the hearing record. Once called to speak, please come to the podium and state 

your name clearly, identify the rule or rules you are commenting on, and whom you represent. 

[Hearing 1]:

I will now open the first hearing and take relevant comments on amendments to North Carolina 

volatile organic compound rules in Section .900 of Chapter 2D. 

These proposed amendments respond to Environmental Protection Agency (EPA) comments on 

North Carolina’s re-designation demonstration and maintenance plan for the Charlotte-GastoniaRock Hill, NC 8-hour Ozone Nonattainment Area. In their comments on North Carolina’s 

submittal, EPA identified the need for an adjustment of applicability of the state’s reasonably 

available control technology (RACT) rules. Section 182(b) (2) of the Clean Air Act (CAA) 

requires RACT for all sources addressed by Control Technique Guidelines (CTGs) issued by 

EPA in areas classified as moderate nonattainment for ozone. North Carolina’s current RACT 

rule, 15A NCAC 02D .0902, applies only to facilities that have the potential to emit (PTE) 

greater than or equal to 100 tons of volatile organic compounds (VOC) per year located in the 

Charlotte-Gastonia-Rock Hill, NC 8-hour Moderate Ozone Nonattainment Area. The proposed 

amendments bring North Carolina into compliance with federal law by extending this 

applicability to all VOC sources covered by any CTG in the nonattainment area. The 

amendments also reduce daily recordkeeping burden for printing operations and exempt cleaning 

operations of coating, ink, and adhesive manufacturing from VOC content limits in response to 

feedback from the industries. 

Rule 15A NCAC 02D .0902, Applicability, is proposed for amendment to bring North Carolina 

into compliance with federal law by extending RACT applicability to all volatile organic VOC 

sources located in the nonattainment area and covered by any CTGs. Rule 15A NCAC 02D 

.0903 Recordkeeping: Reporting: Monitoring, is proposed for amendment to reflect 

incorporation of the monthly recordkeeping alternative for consistency with the CTG provided in 

Rule 15A NCAC 02D .0961 in response to industry representatives’ comments. Rule 15A 

NCAC 02D .0909, Compliance Schedules for Sources in Nonattainment Areas, is proposed for 

IV-11 A-39
3

amendment to clarify compliance schedules for the newly affected facilities. Rule 15A NCAC 

02D .0951 RACT for Sources of Volatile Organic Compounds, is proposed for amendment to 

give affected facilities a choice whether to apply the RACT requirements defined in Section 

.0900 rules or choose RACT requirements demonstrated to the Director to advance attainment. 

Rule 15A NCAC 02D .0961, Offset Lithographic Printing and Letterpress Printing, is proposed 

for amendment to comply with RACT requirements for VOC emissions from heatset inks, 

fountain solutions, and cleaning materials used in offset lithographic printing operations and for 

VOC emissions from heatset inks used in letterpress printing operations. Rule 15A NCAC 02D 

.0962, Industrial Cleaning Solvents, is proposed for amendment to exempt RACT cleaning 

solvent emission limits applicability for resin, coating, ink, and adhesive mixing, molding, and 

application equipment cleaning of coating, ink, and adhesive manufacturing. Rule 15A NCAC 

02Q .0102 Activities Exempted From Permit Requirements, is proposed for amendment to 

update a cross reference. 

{optional script if there are a large number of speakers} 

-------------------------------------------------------------------------------------------------------------------- 

[Hearing officer]: Optional Time Limit 

Many people have requested to speak at this hearing. Due to time constraints, speakers’ 

presentations will be limited to ___ minutes. It would be helpful if speakers would also submit a 

written statement by the close of the comment period for inclusion into the hearing record. 

--------------------------------------------------------------------------------------------------------------------- 

[Hearing officer]: 

I will now take any comments that you may have. 

[SPEAKERS] 

IV-12 A-40
4

[Hearing officer]: 

Is there anyone else who would like to comment? If there are no more comments, then this 

hearing is closed. The hearing record will remain open until February 1, 2013, for additional 

written comments. 

[Hearing 2]: 

I will now open the second hearing and take relevant comments on amendments to Rules 15A 

NCAC 02D .0530, Prevention of Significant Deterioration and 15A NCAC 02D .0531, Sources 

in Nonattainment Areas, to revise North Carolina’s nitrogen oxides (NOx) significance level 

from 140 tons per year to 40 tons per year. Rule 15A NCAC 02D .0530 is also proposed for 

amendment to update the federal cross-reference in the prevention of significant deterioration 

rule to reflect the current federal increments for fine particulate matter promulgated on October 

20, 2010 in the Federal Register (75 FR 64864). 

The EMC amended the prevention of significant deterioration and nonattainment new source 

review permitting rules in 2010 to establish the significance level for NOx for PM2.5 in North 

Carolina at 140 tons per year. As part of its rule review of North Carolina’s state implementation 

plan (SIP), the United States Environmental Protection Agency (USEPA) has determined that, 

while the federal rule allows for a demonstration that NOx is not a significant precursor to 

formation of PM2.5, there is not an allowance for states to establish an alternate significance 

level. As a result, the state significance level must be revised to reflect the federal 40 tons per 

year significance level. 

In 2010, the USEPA added PM2.5 increments under the program. An increment is the maximum 

allowable increase in ambient pollutant concentration. Federal increments were established for 

24-hour and annual averaging periods in Class I, Class II and Class III areas. Adoption of these 

federal increments is required in order for the USEPA to approve North Carolina’s SIP. The 

current date of incorporation in the state rule needs to be updated to reflect the current PM2.5 

IV-13 A-41
5

increments for the current annual and 24-hour national ambient air quality standards established 

by the USEPA. 

{optional script if there are a large number of speakers} 

-------------------------------------------------------------------------------------------------------------------- 

[Hearing officer]: Optional Time Limit 

Many people have requested to speak at this hearing. Due to time constraints, speakers’ 

presentations will be limited to ___ minutes. It would be helpful if speakers would also submit a 

written statement by the close of the comment period for inclusion into the hearing record. 

--------------------------------------------------------------------------------------------------------------------- 

[Hearing officer]: 

I will now take any comments that you may have. 

[SPEAKERS] 

[Hearing officer]: 

Is there anyone else who would like to comment? If there are no more comments, then this 

hearing is closed. The hearing record will remain open until February 1, 2013, for additional 

written comments. 

[Hearing 3]: 

I will now open the third hearing and take relevant comments on amendments proposed to clarify 

the interaction between Rules 15A NCAC 02Q .0102, Exemptions and 02Q .0702, Exemptions. 

IV-14 A-42
6

The Division of Air Quality identified the need for clarification regarding the interaction of the 

air toxics rule specific exemptions with the more broadly applicable rule regarding sources that 

are exempt from the general requirement to obtain a permit. Rule 02Q .0102 specifies which 

activities are exempt from the requirement to obtain an air quality permit. Rule 02Q .0702 

specifies activities which are exempt from the requirement to obtain a permit to emit toxic air 

pollutants (TAP) and not required to be included in TAP demonstrations. The EMC has 

previously determined through rulemaking that many of the activities currently exempt from the 

general requirement to obtain a permit under 02Q .0102(c) should also be exempt from air toxics 

demonstration and permitting requirements as identified in 02Q .0702(a)(1) through (a)(24). 

Existing language in 02Q .0102(b)(7) needs to be clarified to reflect this interaction relative to 

smaller sources such that small sources not be required to be included in an air toxics 

demonstration or permit retain the exemption from having to obtain an air quality permit. 

{optional script if there are a large number of speakers} 

-------------------------------------------------------------------------------------------------------------------- 

[Hearing officer]: Optional Time Limit 

Many people have requested to speak at this hearing. Due to time constraints, speakers’ 

presentations will be limited to ___ minutes. It would be helpful if speakers would also submit a 

written statement by the close of the comment period for inclusion into the hearing record. 

--------------------------------------------------------------------------------------------------------------------- 

[Hearing officer]: 

I will now take any comments that you may have. 

[SPEAKERS] 

[Hearing officer]: 

IV-15 A-43
7

Is there anyone else who would like to comment? If there are no more comments, then this 

hearing is closed. The hearing record will remain open until February 1, 2013, for additional 

written comments. 

IV-16 A-44
CHAPTER V 

COMMENTS DURING THE COMMENT PERIOD 

INDEX OF COMMENTERS 

NAME REPRESENTING PAGE

Mark Huncik V-2

R. Scott Davis United States Environmental Protection Agency V-4

V-1 A-45


V-4 A-48
V-5 A-49
This page is intentionally blank 

A-50
CHAPTER VI 

INDEX OF ATTACHMENTS 

ATTACHMENTS PAGE

Revisions to New Source Review and Prevention of Significant Deterioration (PSD) 

Nitrogen Oxides (NOx) Significance Level for PM2.5 and PM2.5 Increment Fiscal 

Note

VI-2

Addendum to Fiscal Note VI-24

U.S. Court of Appeals for the District of Columbia Circuit, January 4, 2013, Sierra 

Club vs. United States Environmental Protection Agency (EPA), No. 08-1250

VI-26

U.S Court of Appeals for the District of Columbia Circuit, January 22, 2013, 

National Resources Defense Council and Sierra Club vs. EPA, No. 10-1413

VI-44

Implementation of the New Source Review (NSR) Program for Particulate Matter 

Less Than 2.5 Micrometers (PM2.5), 73 FR 28321 (5/16/2008)

VI-66

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), 75 FR 64864 (10/20/2010)

VI-96

Federal Register Notices Not Included in Hearing Record VI-140

VI-1 A-51
Draft – 10/9/2012 1 

ECONOMIC ANALYSIS 

Rule Citation Number: 15A NCAC 02D .0530, Prevention of Significant Deterioration 

 15A NCAC 02D .0531 Sources in Nonattainment Areas 

Rule Topic: Revisions to New Source Review and Prevention of Significant Deterioration 

(PSD) Nitrogen Oxides (NOx) Significance Level for PM2.5 (512) and PM2.5

Increment (516)

DENR Division: Division of Air Quality 

Agency Contact: Joelle Burleson, Rule Development Branch Supervisor 

 Division of Air Quality (DAQ) 

(919) 707-8720 

Joelle.Burleson@ncdenr.gov

Analyst: Patrick Knowlson, DAQ 

 (919) 707-8711 

 patrick.knowlson@ncdenr.gov

Impact Summary: State government: Yes 

Local government: No

Substantial impact: No

Federal government: No

Private Sector: Yes 

Authority: G.S. 143-215.3(a)(1); 143-215.107(a)(3); 143-215.107(a)(5); 143-

215.107(a)(7); 143-215.108(b); 150B-21.6;

Necessity: The proposed rule amendments would revise North Carolina’s nitrogen oxides 

significance level from 140 tons per year to 40 tons per year. The proposed rule 

amendments also update the federal cross-reference in the Prevention of Significant 

Deterioration (PSD) rule to reflect the current federal increments for fine particulate 

matter (PM2.5). These proposed rule changes are necessary to comply with federal 

rules and are consistent with the principles of Executive Order 70. 

I. Executive Summary 

This rulemaking package consists of two major rule amendments. First, this proposal would revise 

North Carolina’s nitrogen oxides significance level from 140 tons per year to 40 tons per year. The 

second proposed amendment will update the federal cross-reference in the Prevention of Significant 

Deterioration (PSD) rule to reflect the current federal increments for fine particulate matter (PM2.5).

The proposed text changes are located in Appendix A. 

VI-2 A-52
Draft – 10/9/2012 2 

The Environmental Management Commission (EMC) amended the New Source Review (NSR) and 

Prevention of Significant Deterioration (PSD) permitting rules in 2010 to establish the significance 

level for nitrogen oxides (NOx) for PM2.5 in North Carolina at 140 tons per year (tpy). This 

significance level was based on monitoring and modeling data indicating that NOx is a lessor 

contributor to the formation of PM2.5 than sulfur dioxide (SO2). As part of its rule review of North 

Carolina’s state implementation plan (SIP), the United States Environmental Protection Agency 

(USEPA) has determined that, while the federal rule allows for a demonstration that NOx is not a 

significant precursor to formation of PM2.5, there is not an allowance for states to establish an 

alternate significance level. As a result, the state significance level must be revised to reflect the 

federal 40 tpy significance level in USEPA PM2.5 Implementation Rule. 

In 2010, the USEPA added PM2.5 increments under the program. An increment is the maximum 

allowable increase in ambient pollutant concentration. Federal increments were established for 24-

hour and annual averaging periods in Class I, Class II and Class III areas. Adoption of these federal 

increments is required in order for the USEPA to approve North Carolina’s SIP. The current date of 

incorporation in the state rule needs to be updated to reflect the current PM2.5 increments for the 

current annual and 24-hour NAAQS established by the USEPA. 

There are no anticipated costs or benefits associated with the change in NOx significance level for 

PM2.5 because the significance level of NOx for ozone is already 40 tpy (see 40 CFR 51.166(b)(23) 

and 40 CFR 52.21(b)(23)). Affected facilities have already implemented additional emission 

controls to meet the requirements for the NOx significance level for ozone. State government and 

the private sector will face additional costs to incorporate the federal PM2.5 increments PSD 

program. Based on an average of six PSD applications received by the Division of Air Quality 

(DAQ) per year, the total annual impact to the private sector would be approximately $134,000. 

DAQ would have about $17,000 in additional expenses. The overall total cost increase to all entities 

would be approximately $151,000 per year. These cost estimates are based on the assumption that 

all applicant facilities will need the highest level of analysis; true costs may be lower. 

North Carolina will benefit from this proposed policy change because our NOx significance level 

will comply with federal regulations and the federal government will approve our SIP and fund 

state air quality programs. There will not be any change in the health benefits to the public as a 

result of these amendments. Changing the NOx significance levels will have no impact on 

emissions. The PM2.5 increments are protective elements of a NSR program designed to prevent a 

violation of the National Ambient Air Quality Standard (NAAQS) for PM2.5. Adoption of these 

federal increments is required in order for the USEPA to approve North Carolina’s SIP.

The proposed effective date for these proposed rule changes is projected to be May 1, 2013. 

 

II. Background 

The Clean Air Act requires the USEPA to set National Ambient Air Quality Standards (NAAQS) 

for pollutants considered harmful to public health and the environment. The NAAQS has two types 

of national air quality standards, a primary standard and a secondary standard. Primary standards 

set limits to protect public health, including the health of "sensitive" populations such as asthmatics, 

VI-3 A-53
Draft – 10/9/2012 3 

children, and the elderly. Secondary standards set limits to protect public welfare, including 

protection against decreased visibility, damage to animals, crops, vegetation, and buildings. The 

NAAQS define the maximum permissible concentrations for certain pollutants, known as criteria 

pollutants. 

A Clean Air Act program known as “New Source Review” (NSR) requires an analysis of emissions 

from new sources or significant modifications of existing sources. This analysis protects human 

health by ensuring air emissions do not exceed the NAAQS for various airborne pollutants. The 

NSR program consists of two permitting programs. The first permitting program is the 

Nonattainment New Source Review (NA NSR) program. The second NSR program is called 

Prevention of Significant Deterioration (PSD). These two programs are contained in North 

Carolina’s SIP in Rules 15A NCAC 02D .0530 and .0531. 

Either NA NSR or PSD permits are required for all new or existing stationary point sources of 

pollution, such as factories, that plan major modifications to their facility which may increase 

emissions above particular pollutant significance levels. The term “Significance level” refers to a 

facility’s potential to emit (PTE) pollutants subject to regulation above a specified emissions 

threshold. If the threshold is exceeded, then the source is evaluated under the NSR program. “Major 

modification” means any physical change or change in the method of operation of a major 

stationary source that would result in a significant emissions increase of a regulated NSR pollutant 

and a significant net emissions increase of that pollutant from the major stationary source. 

The NA NSR program requirements are used for screening permit applications from major 

stationary sources located in nonattainment areas. Major stationary source means one that emits, 

or has the potential to emit, 100 tons per year or more of any regulated NSR pollutant (40 CFR 

51.166(b)(50)). A nonattainment area is an area designated by USEPA as not meeting the NAAQS 

minimal concentration for one or more of the NAAQS pollutants. Nonattainment areas are always 

designated as nonattainment for one or more NAAQS such as nonattainment for ozone or 

nonattainment for VOC and ozone. The area's particular nonattainment designation influences the 

permit screening process. An NA NSR permit screening determines permit requirements to control 

the specific NAAQS pollutant for which the area is in nonattainment. 

NA NSR permitted facilities are required to obtain emission offsets, which are emission reductions 

from existing sources in nonattainment area. Offsets are credited to existing facilities that reduce 

emissions by installing emission control equipment beyond rule requirements; modifying 

production processes; or by shutting down one or more emission sources. These offsets ensure that 

NAAQS emissions within the nonattainment area do not increase and nonattainment area continues 

to work toward reaching attainment. 

The PSD program does not prevent sources from increasing emissions and is used in attainment 

areas. Attainment areas are delineated regions designated by USEPA as meeting all NAAQS. The 

PSD program is designed to maintain that classification. While the NA NSR screening is designed 

to limit the nonattainment NAAQS pollutant, the PSD screening reviews all the NAAQS pollutants. 

PSD is designed to: 

1. protect public health and welfare; 

VI-4 A-54
Draft – 10/9/2012 4 

2. preserve, protect, and enhance the air quality in national parks, national wilderness areas, 

national monuments, national seashores, and other areas of special national or regional 

natural, recreational, scenic, or historic value; 

3. insure that economic growth will occur in a manner consistent with the preservation of 

existing clean air resources; and 

4. assure that any decision to permit increased air pollution is made only after careful 

evaluation of all the consequences of such a decision and after adequate procedural 

opportunities for informed public participation in the decision making process. 

Once an NA NSR or PSD requirement is triggered for a major stationary source or a major 

modification by even a single pollutant, a best available control technology review must be done for 

each PSD regulated pollutant that is emitted in significant quantities. 

Federal and State Regulations for PM2.5 are Different 

Fine Particular Matter (PM2.5) is particles less than 2.5 micrometers in diameter and is

interchangeably referred to as "fine" particles. Fine particles in the atmosphere are made up of a 

complex mixture of directly emitted and secondarily formed components. The United States 

Environmental Protection Agency (USEPA) added PM2.5 to the NAAQS pollutants on May 8, 2008 

(72 FR 20586). The USEPA’s Clean Air Fine Particulate Implementation Rule, commonly referred 

to as the PM2.5 Implementation Rule, guides states as they develop State Implementation Plans 

(SIP) in response to annual or daily PM2.5 NAAQS. 

NOx Significance level 

The PM2.5 Implementation Rule establishes a hierarchy of precursor pollutants. Precursors are 

gaseous emissions of compounds that chemically combine with other compounds some time later in 

the atmosphere to form PM2.5. Sulfur Dioxide (SO2) and nitrogen oxides (NOx) are significant 

precursors. USEPA has determined that Volatile Organic Compounds (VOCs) and ammonia (NH3) 

are presumed not to be significant precursors. 

In the PM2.5 Implementation Rule, the USEPA set the following significant emission rates or 

significance levels for PM2.5; 10 tons per year (tpy) of direct PM2.5 emissions, 40 tpy of sulfur 

dioxide emissions, or 40 tpy of nitrogen oxides emissions. Direct PM2.5 consists of both solid and 

condensable PM2.5 emissions leaving the stack and entering the atmosphere. Direct PM2.5 does not 

include the PM2.5 precursors (SO2 and NOx).

In 2010, the Environmental Management Commission (EMC) adopted amendments to the state NA 

NSR and PSD permitting rules to incorporate requirements relative to the PM2.5 Implementation 

Rule. The state rule amendments established the significance level for NOx for PM2.5 in North 

Carolina at 140 tons per year based on monitoring and modeling data supporting that NOx is a 

lessor contributor to the formation of PM2.5 than SO2. 

As part of its review of the rules for incorporation into North Carolina SIP, the USEPA has 

determined that, while the federal rule allows for a demonstration that NOx is not a significant 

VI-5 A-55
Draft – 10/9/2012 5 

precursor to formation of PM2.5, there is no allowance for a state to establish an alternate 

significance level. As a result, the significance level needs to be revised to reflect the 40 tpy 

significance level in the implementation rule. 

PM2.5 Increment 

 

PSD increments were developed by USEPA and enacted in December 2010 to prevent the air 

quality in attainment areas from deteriorating to the level set by the NAAQS. The NAAQS is a 

maximum allowable concentration "ceiling." A PSD increment, on the other hand, is the maximum 

allowable increase in concentration that is allowed to occur above a baseline concentration for a 

pollutant. The baseline concentration (referred to as “background” in Figure 1 below) is defined for 

each pollutant and, in general, is the ambient concentration which exists at the time the first 

complete PSD permit application affecting the area is submitted. Significant deterioration is said to 

occur when the amount of new pollution would exceed the applicable PSD increment. It is 

important to note, however, that the air quality cannot deteriorate beyond the concentration allowed 

by the applicable NAAQS, even if not all of the PSD increment is consumed. For PM2.5, this means 

the Class II increment of 4 ug/m3 for a new or modified source might not be reached before the 

applicable PM2.5 NAAQS is exceeded. An illustration on PM2.5 increments is included below. 

Figure 1 

VI-6 A-56
Draft – 10/9/2012 6 

There are three area classes are part of the increment system originally established by Congress. 

Congress designated Class I areas (including certain national parks and wilderness areas) as areas 

of special national concern, where the need to prevent deterioration of air quality is the greatest. 

Areas not designated as Class I were designated as Class II. The increments of Class II areas

are larger than those of Class I areas and allow for a moderate degree of emissions growth. For 

future redesignation purposes, Congress defined a Class III classification to allow the redesignation 

of any existing Class II area for which a state may desire to promote a higher level of industrial 

development (and emissions growth). Thus, Class III areas are allowed to have the greatest amount 

of pollutant increase of the three area classes while still achieving the NAAQS. To date, there have 

been no redesignations made to establish a Class III area. 

The USEPA promulgated the increments for PM2.5 on October 20, 2010 (75 FR 64864). North 

Carolina’s prevention of significant deterioration rules incorporates various provisions of the 

corresponding federal regulations by reference as of a certain date. The current date of 

incorporation in the state rule needs to be updated to reflect the current PM2.5 increments for the 

current annual and 24-hour NAAQS established by the USEPA. The annual and 24-hour NAAQS 

and corresponding increments were set by USEPA as follows: 

 

Table 1. USEPA PM2.5 Increments

NAAQS (ug/m3) Increment (ug/m3)

 Area 

Class I Class II Class III

Annual 15 1 4 8

24-hour 35 2 9 18

The Significant Impact Limit (SIL) is a screening tool that USEPA developed to evaluate the 

impact of new sources and major modifications on the PM2.5 NAAQS and PSD increments. If the 

highest modeled concentrations are greater than the SILs (see Table 2), a full impact, PSD 

increment analysis is conducted for the significant impact area (SIA). The SIA is a circular area 

with a radius extending out to the most distant point where the modeling predicts a significant 

ambient impact (not to exceed 50 kilometers) and represents the geographical area for which the 

NAAQS and PSD increment analysis is conducted. 

Table 2. USEPA PM2.5 Significant Impact Limits

SILs (ug/m3)

 Area 

Class I Class II Class III

Annual 0.06 0.3 0.3

24-hour 0.07 1.2 1.2

The Significant Monitoring Concentration (SMC), is a screening tool that may be used to determine 

if a source must submit to the permitting authority one year of pre-construction air quality 

monitoring data prior to constructing or modifying a facility. If a proposed source’s predicted 

impact is less than the SMC, the source’s impact may be considered de minimis for monitoring 

VI-7 A-57
Draft – 10/9/2012 7 

purposes, and the reviewing authority could exempt the applicant from the preconstruction 

monitoring requirement. The reviewing authority also may exempt the applicant from the 

monitoring requirement if the existing air quality in the area is shown to be less than the SMC. The 

USEPA set an SMC 4 μg/m3 (24-hour average) for PM2.5. 

As part of the full impact analysis, all facility emissions of PSD criteria pollutants and for which 

PSD increments have been established (PM10, SO2, NOx and PM2.5) are evaluated to determine the 

individual source emissions that consume increment. These sources are included in the PSD 

increment modeling analysis. There are two types of sources emissions that are included in the 

analysis: all source increases within the county that have occurred since the baseline data was 

established and all sources located within the significant impact areas and established after the 

baseline data was established. 

All new sources or source emission increases that have occurred since the Minor Source Baseline 

Date (MiSBD) was established for the county in which the PSD application is being submitted must 

be modeled. A list of the MiSBDs by county is provided on the DAQ website at 

http://daq.state.nc.us/permits/psd. Since the MiSBD in NC is county specific, the modeling domain 

may contain multiple MiSBDs to apply to the source selection process. Major sources in existence 

prior to the EPA-established Major Source Baseline Date (MSBD) are excluded from the increment 

modeling analysis. 

Facility emission rates must reflect the maximum allowable operating conditions as expressed by 

the federally enforceable emissions limit, operating level, and operating factor for each applicable 

pollutant and averaging time. Note: operating levels less than 100 percent of capacity may also 

need to be modeled where differences in stack parameters associated with the lower operating 

levels could result in higher ground level concentrations. 

Off-site increment consuming sources that were created on or after the MiSBD and that are within 

the SIA also must be included in the PSD increment analysis. In addition, all increment consuming 

sources within 50 km (screening area) of the SIA must be evaluated for inclusion in the offsite 

increment source inventory. Offsite sources within the screening area can be excluded from the 

modeling if their facility-wide emission rate in tons per year is less than 20D (where D is defined as 

the distance from the offsite source to the PSD facility being modeled for short term emissions and 

as the distance from the offsite source to the nearest boundary of the SIA for long term emissions). 

Additional information on PSD modeling can be found in North Carolina PSD Modeling Guidance

in Appendix B of this document. 

III. Costs and Benefits by Affected Party 

The baseline for this analysis is the current PSD and NA NSR rules found in Rule 15A NCAC 02D 

.0530, Prevention of Significant Deterioration; and 02D .0531, Sources in Nonattainment Areas. 

The change from the baseline is a decrease in the significance level on the precursor NOx from the 

current North Carolina significance level of 140 tpy to 40 tpy that the USEPA is requiring North 

Carolina to adopt and the update to the federal cross-reference in the PSD rule to reflect the current 

federal increments for PM2.5.

VI-8 A-58
Draft – 10/9/2012 8 

Public 

The rule amendments to both 15A NCAC 02D .0530 and .0531 will decrease the NOx significance 

level for PM2.5 from 140 tpy to 40 tpy but the actual emissions of regulated pollutants would not 

increase or decrease in response to the proposed amendment since the significance level for ozone 

continues to be 40 tpy. The rule amendment to 15A NCAC 02D .0530 will also update the federal 

cross-reference in the PSD rule to reflect the increments set by USEPA for fine particulate matter 

(PM2.5). Although there is not any expected quantifiable health benefits to the public as a result of 

these amendments since all areas of the state are currently in attainment for PM2.5, the NOx 

significance levels and the PM2.5 increments are elements of a NSR program to help prevent a 

violation of the National Ambient Air Quality Standard (NAAQS) for PM2.5. The NAAQS is set at 

a level to be protective of both public health and the environment. The public would benefit from 

the state retaining its attainment status through the use of the NOx significance levels and the PM2.5

increments. 

North Carolina will benefit from this proposed policy change because our NOx significance level 

will comply with federal regulations and the federal government will approve our State 

Implementation Plan (SIP) and fund state air quality programs. The primary benefit of this set of 

amendments is to address applicability consistent with the requirements of the Clean Air Act and 

ensure approval of the SIP by USEPA. Without the proposed rule change, USEPA will not be able 

to approve the current version of the plan. If the state does not have a plan that meets federal 

requirements, the EPA approval can require corrective action within required timeframes or 

implement a federal plan for North Carolina. A federal plan may require solutions that are not the 

best to fit a particular area and are less preferable than having a state-controlled program. If not 

eventually corrected, potential sanctions on highway transportation funding could also occur. 

Private Sector 

NOx Significance Level 

Currently, North Carolina has two maintenance areas for PM2.5 which are Hickory (Catawba 

County) and Greensboro/Winston-Salem/High Point (Davidson and Guilford Counties). A 

maintenance area is an area that was designated nonattainment for one of the NAAQS, but later met 

the standard and was re-designated to attainment status. These two areas were re-designated based 

on ambient monitoring data from nonattainment to attainment on December 19, 2011. There are no 

nonattainment areas for PM2.5 in North Carolina at this time. 

Lowering the NOx significance level for PM2.5 from 140 tpy to 40 tpy will not impact any new or 

existing sources located in maintenance areas because the NOx significance level is already 40 tpy 

for ozone. Private facilities have already invested in pollution control technologies to comply with 

the requirements for NOx in ozone maintenance areas. Actual emissions of regulated pollutants 

would not increase or decrease in response to the proposed amendment. 

VI-9 A-59
Draft – 10/9/2012 9 

PM2.5 Increment 

A PSD increment analysis requires additional engineering and modeling. Since most likely the 

PM2.5 increment analysis will be incorporated into an analysis with other pollutants, this will not be 

a standalone project, thus the cost will be minimized. DAQ has estimated incremental cost 

increased based on three different scenarios: 

1) Scenario 1: Below the Significant Impact Level (SIL) thus minimal modeling will be 

needed, i.e. only level 1 analysis. 

2) Scenario 2: Exceeds the SIL and thus a Class II increment analysis will be required, i.e. 

level 1 and 2 analysis would be needed. 

3) Scenario 3: Exceeds the SIL, a Class II increment analysis will be required and a Class 

I Increment analysis is required, i.e. level 1, 2, and 3 analysis would be needed. 

Consulting firms usually perform the PSD analysis for an affected facility. The facility will likely 

have several PM2.5 sources and offsite sources. The consulting firm will collect data and perform 

modeling for all of these sources. According to the permitting section of DAQ, an offsite source 

inventory would cost approximately $5,000 for the facility to generate. Industry consultants 

contacted by the Air Quality Analysis Branch (AQAB) of the Division of Air Quality (DAQ), 

estimate it would cost approximately $4,400 to complete a level 1 analysis (Scenario 1 above). 

If based on minimal modeling the SIL is exceeded, then a Class II increment analysis would also be 

required (Scenario 2 above). For level 2 analysis, there would be approximately 40 hours of data 

gathering, 40 hours to assemble the model with the source and parameter inputs and 32 hours of 

computer time to run the model. A level 2 analysis would add approximately $3,000 to the overall 

costs for additional modeling runs. If the source is located in a Class I area, a Class I increment 

analysis, or level 3 analysis, would also be required (Scenario 3 above). A level 3 analysis would 

add approximately $10,000 to the overall cost for an increment analysis for the expanded modeling 

and more intensive modeling requirements. 

DAQ has averaged six PSD permit applications annually for all pollutants since 1999. PM2.5 is a 

relatively new regulated pollutant so the projected number of PSD permit applications that require a 

PM2.5 increment modeling effort is unknown. For this analysis, it is assumed that all of the PSD 

permit applications will require an evaluation for PM2.5. Until DAQ starts receiving PSD permit 

application with PM2.5 increment calculations, it is unknown how many applications on average 

will require a scenario one, two or three modeling effort. This cost estimate was formulated with 

the assumption that all six PSD applications would require a Scenario 3 modeling effort. In reality, 

this is highly unlikely to occur. For this reason, these cost estimates present a highest cost scenario. 

Under Scenario 3, the total cost for adding a PM2.5 increment analysis to each PSD permit 

application would be estimated to be $17,400 for the modeling and $5,000 for the offsite source 

inventory. The annual cost to affected facilities for all PSD permits submitted to DAQ for review 

(assuming there would be 6 applications per year) would be approximately $134,000. 

Currently, the Significant Monitoring Concentration (SMC) is not used in a PSD analysis. The NC 

Division of Air Quality (DAQ) does not require one year of preconstruction monitoring. The State 

VI-10 A-60
Draft – 10/9/2012 10 

has an extensive monitoring network. The SMC are incorporated by reference in the rule. If there 

was a need to require one year of preconstruction monitoring in the future, an affected source could 

be exempted from the monitoring requirement and associated monitoring costs if the predicted 

impact is less than the SMC. DAQ does not anticipate using the SMC in the future. 

State Agencies 

NOx Significance Level 

The rule amendment will not result in an increase or decrease in PSD permit applications. PSD 

permits are currently required if there is an increase in NOx PTE emissions of 40 tpy under the 

ozone standard. Lowering the NOx significance level for PM2.5 maintenance areas from 140 tpy to 

40 tpy will not increase the number of PSD permits. 

PM2.5 Increments 

The Air Quality Analysis Branch (AQAB) of the Division of Air Quality would require additional 

time to review the PM2.5 increment analysis in a PSD permit application. This review would not 

appreciably change how a PSD permit application review is performed but would add some time 

cost to review the PM2.5 increment analysis contained in the permit application. A first level 

analysis would add an additional eight hours to a PSD review. It is assumed a Meteorologist II 

employee with 10 years of experience and a salary of $56,000 will review the PSD permit 

application. Using the NC Office of State Personnel Employee Compensation Calculator, a 

Meteorologist II hourly compensation is approximately $40. The increase for a first level analysis 

would be $320. A second level analysis would add approximately three days to the review for a 

total labor cost of $960. A third level analysis would add a full week to the review process for an 

additional $1,600 dollars in costs to DAQ. Using the same assumption that all PSD permit 

applications would require level 1, 2, and 3 analyses (i.e. Scenario 3), the total impact to DAQ 

would be about $2,900 per PSD permit application. Based on an average of six PSD applications 

per year, the annual cost to DAQ would be approximately $17,300. 

Uncertainty 

There is a small chance that the proposed rule changes may lead to a higher impact than estimate 

above if the USEPA goes ahead with the proposed new PM2.5 standards on June 14, 2012. This new 

USEPA proposal would set a new primary annual PM2.5 standard within a range of 12 to 13 ug/m3. 

The current annual standard is 15 ug/m3. There is the potential for costs to new or existing sources 

if there is a violation of the PM2.5 NAAQS that results in the USEPA designating an area to 

nonattainment for PM2.5 at some point in the future. In non-attainment areas, the PSD increments 

are not used and affected facilities would be required to obtain emission offsets from existing 

sources. Also modeling is more extensive in nonattainment areas. 

The Division of Air Quality thinks, however, that it is unlikely that there will be a violation of the 

PM2.5 NAAQS at any point in the foreseeable future. NC’s highest design value (based on 2009-11 

data) is 11.2 ug/m3, which is below the more stringent proposed standard at the federal level. State 

VI-11 A-61
Draft – 10/9/2012 11 

actions to implement the Clean Smokestacks Act, Vehicle Inspection and Maintenance Program 

and federal Tier 2 engine standards have substantially reduced the amount of PM2.5 in North 

Carolina’s air. 

The proposed rule changes do not meet the threshold for a substantial fiscal impact. 

VI-12 A-62
Appendix A 

Draft – 10/9/2012 1 

1 15A NCA 02D .0530 is proposed for amendment as follows: 

2

3 15A NCAC 02D .0530 PREVENTION OF SIGNIFICANT DETERIORATION 

4 (a) The purpose of the Rule is to implement a program for the prevention of significant deterioration of air quality 

5 as required by 40 CFR 51.166. 

6 (b) For the purposes of this Rule the definitions contained in 40 CFR 51.166(b) and 40 CFR 51.301 apply except 

7 the definition of "baseline actual emissions." For the purposes of this Rule: 

8 (1) "Baseline actual emissions" means the rate of emissions, in tons per year, of a regulated new 

9 source review (NSR) pollutant, as determined in accordance with Parts (A) through (C) of this 

10 Subparagraph: 

11 (A) For an existing emissions unit, baseline actual emissions means the average rate, in tons 

12 per year, at which the emissions unit actually emitted the pollutant during any 

13 consecutive 24-month period selected by the owner or operator within the 5-year period 

14 immediately preceding the date that a complete permit application is received by the 

15 Division for a permit required under this Rule. The Director shall allow a different time 

16 period, not to exceed 10 years immediately preceding the date that a complete permit 

17 application is received by the Division, if the owner or operator demonstrates that it is 

18 more representative of normal source operation. For the purpose of determining baseline 

19 actual emissions, the following apply:

20 (i) The average rate shall include fugitive emissions to the extent quantifiable, and 

21 emissions associated with startups, shutdowns, and malfunctions; 

22 (ii) The average rate shall be adjusted downward to exclude any non-compliant 

23 emissions that occurred while the source was operating above any emission 

24 limitation that was legally enforceable during the consecutive 24-month period; 

25 (iii) For an existing emission unit (other than an electric utility steam generating 

26 unit), the average rate shall be adjusted downward to exclude any emissions that 

27 would have exceeded an emission limitation with which the major stationary 

28 source must currently comply. However, if the State has taken credit in an 

29 attainment demonstration or maintenance plan consistent with the requirements 

30 of 40 CFR 51.165(a)(3)(ii)(G) for an emission limitation that is part of a 

31 maximum achievable control technology standard that the Administrator 

32 proposed or promulgated under part 63 of the Code of Federal Regulations, the 

33 baseline actual emissions shall be adjusted to account for such emission 

34 reductions; 

35 (iv) For an electric utility steam generating unit, the average rate shall be adjusted 

36 downward to reflect any emissions reductions under G.S. 143-215.107D and for 

37 which cost recovery is sought pursuant to G.S. 62-133.6; 

VI-13 A-63
Appendix A 

Draft – 10/9/2012 2 

1 (v) For a regulated NSR pollutant, when a project involves multiple emissions units, 

2 only one consecutive 24-month period shall be used to determine the baseline 

3 actual emissions for all the emissions units being changed. A different 

4 consecutive 24-month period for each regulated NSR pollutant can be used for 

5 each regulated NSR pollutant; and 

6 (vi) The average rate shall not be based on any consecutive 24-month period for 

7 which there is inadequate information for determining annual emissions, in tons 

8 per year, and for adjusting this amount if required by Subparts (ii) and (iii) of 

9 this Part; 

10 (B) For a new emissions unit, the baseline actual emissions for purposes of determining the 

11 emissions increase that will result from the initial construction and operation of such unit 

12 shall equal zero; and thereafter, for all other purposes, shall equal the unit's potential to 

13 emit; and 

14 (C) For a plantwide applicability limit (PAL) for a stationary source, the baseline actual 

15 emissions shall be calculated for existing emissions units in accordance with the 

16 procedures contained in Part (A) of this Subparagraph, and for a new emissions unit in 

17 accordance with the procedures contained in Part (B) of this Subparagraph; 

18 (2) In the definition of "net emissions increase," the reasonable period specified in 40 CFR 

19 51.166(b)(3)(ii) is seven years; 

20 (3) The limitation specified in 40 CFR 51.166(b)(15)(ii) does not apply; and 

21 (4) Particulate matter PM2.5 significant levels in 40 CFR 51.166(b)(23)(i) are incorporated by 

22 reference except as otherwise provided in this Rule. A net emission increase or the potential of a 

23 source to emit nitrogen oxide emissions shall be significant if the rate of emissions would equal or 

24 exceed 140 tons per year. Sulfur dioxide and nitrogen oxides are precursor to PM2.5 in all 

25 attainment and unclassifiable areas. Volatile organic compounds and ammonia are not significant 

26 precursors to PM2.5. 

27 (c) All areas of the State are classified as Class II except that the following areas are Class I: 

28 (1) Great Smoky Mountains National Park; 

29 (2) Joyce Kilmer Slickrock National Wilderness Area; 

30 (3) Linville Gorge National Wilderness Area; 

31 (4) Shining Rock National Wilderness Area; and 

32 (5) Swanquarter National Wilderness Area. 

33 (d) Redesignations of areas to Class I or II may be submitted as state proposals to the Administrator of the 

34 Environmental Protection Agency (EPA), if the requirements of 40 CFR 51.166(g)(2) are met. Areas may be 

35 proposed to be redesignated as Class III, if the requirements of 40 CFR 51.166(g)(3) are met. Redesignations may 

36 not, however, be proposed which would violate the restrictions of 40 CFR 51.166(e). Lands within the boundaries of 

37 Indian Reservations may be redesignated only by the appropriate Indian Governing Body. 

VI-14 A-64
Appendix A 

Draft – 10/9/2012 3 

1 (e) In areas designated as Class I, II, or III, increases in pollutant concentration over the baseline concentration shall 

2 be limited to the values set forth in 40 CFR 51.166(c). However, concentration of the pollutant shall not exceed 

3 standards set forth in 40 CFR 51.166(d). 

4 (f) Concentrations attributable to the conditions described in 40 CFR 51.166(f)(1) shall be excluded in determining 

5 compliance with a maximum allowable increase. However, the exclusions referred to in 40 CFR 51.166(f)(1)(i) or 

6 (ii) shall be limited to five years as described in 40 CFR 51.166(f)(2). 

7 (g) Major stationary sources and major modifications shall comply with the requirements contained in 40 CFR 

8 51.166(i) and (a)(7) and by extension in 40 CFR 51.166(j) through (o) and (w). The transition provisions allowed by 

9 40 CFR 52.21 (i)(11)(i) and (ii) and (m)(1)(vii) and (viii) are hereby adopted under this Rule. The minimum 

10 requirements described in the portions of 40 CFR 51.166 referenced in this Paragraph are hereby adopted as the 

11 requirements to be used under this Rule, except as otherwise provided in this Rule. Wherever the language of the 

12 portions of 40 CFR 51.166 referenced in this Paragraph speaks of the "plan," the requirements described therein 

13 shall apply to the source to which they pertain, except as otherwise provided in this Rule. Whenever the portions of 

14 40 CFR 51.166 referenced in this Paragraph provide that the State plan may exempt or not apply certain 

15 requirements in certain circumstances, those exemptions and provisions of nonapplicability are also hereby adopted 

16 under this Rule. However, this provision shall not be interpreted so as to limit information that may be requested 

17 from the owner or operator by the Director as specified in 40 CFR 51.166(n)(2). 

18 (h) New natural gas-fired electrical utility generating units for which cost recovery is sought pursuant to G. S. 62-

19 133.6 shall install best available control technology for NOX and SO2, regardless of applicability of the rest of this 

20 Rule. 

21 (i) 40 CFR 51.166(w)(10)(iv)(a) is changed to read: "If the emissions level calculated in accordance with Paragraph 

22 (w)(6) of this Section is equal to or greater than 80 percent of the PAL [plant wide applicability limit] level, the 

23 Director shall renew the PAL at the same level." 40 CFR 51.166(w)(10)(iv)(b) is not incorporated by reference. 

24 (j) 15A NCAC 02Q .0102 and .0302 are not applicable to any source to which this Rule applies. The owner or 

25 operator of the sources to which this Rule applies shall apply for and receive a permit as required in 15A NCAC 

26 02Q .0300 or .0500. 

27 (k) When a particular source or modification becomes a major stationary source or major modification solely by 

28 virtue of a relaxation in any enforceable limitation which was established after August 7, 1980, on the capacity of 

29 the source or modification to emit a pollutant, such as a restriction on hours of operation, then the provisions of this 

30 Rule shall apply to the source or modification as though construction had not yet begun on the source or 

31 modification.

32 (l) The provisions of 40 CFR 52.21(r)(2) regarding the period of validity of approval to construct are incorporated 

33 by reference except that the term "Administrator" is replaced with "Director". 

34 (m) Volatile organic compounds exempted from coverage in 40 CFR 51.100(s) shall be exempted when calculating 

35 source applicability and control requirements under this Rule. 

36 (n) The degree of emission limitation required for control of any air pollutant under this Rule shall not be affected 

37 by: 

VI-15 A-65
Appendix A 

Draft – 10/9/2012 4 

1 (1) that amount of a stack height, not in existence before December 31, 1970, that exceeds good 

2 engineering practice; or 

3 (2) any other dispersion technique not implemented before then. 

4 (o) A substitution or modification of a model as provided for in 40 CFR 51.166(l) is subject to public comment 

5 procedures in accordance with the requirements of 40 CFR 51.102. 

6 (p) Permits may be issued on the basis of innovative control technology as set forth in 40 CFR 51.166(s)(1) if the 

7 requirements of 40 CFR 51.166(s)(2) have been met, subject to the condition of 40 CFR 51.166(s)(3), and with the 

8 allowance set forth in 40 CFR 51.166(s)(4). 

9 (q) If a source to which this Rule applies impacts an area designated Class I by requirements of 40 CFR 51.166(e), 

10 notice to EPA shall be provided as set forth in 40 CFR 51.166(p)(1). If the Federal Land Manager presents a 

11 demonstration described in 40 CFR 51.166(p)(3) during the public comment period or public hearing to the Director 

12 and if the Director concurs with this demonstration, the permit application shall be denied. Permits may be issued on 

13 the basis that the requirements for variances as set forth in 40 CFR 51.166(p)(4), (p)(5) and (p)(7), or (p)(6) and 

14 (p)(7) have been satisfied. 

15 (r) A permit application subject to this Rule shall be processed in accordance with the procedures and requirements 

16 of 40 CFR 51.166(q). Within 30 days of receipt of the application, applicants shall be notified if the application is 

17 complete as to initial information submitted. Commencement of construction before full prevention of significant 

18 deterioration approval is obtained constitutes a violation of this Rule. 

19 (s) Approval of an application with regard to the requirements of this Rule does not relieve the owner or operator of 

20 the responsibility to comply with applicable provisions of other rules of this Subchapter or Subchapter 02Q of this 

21 Title and any other requirements under local, state, or federal law. 

22 (t) When a source or modification is subject to this Rule the following procedures apply: 

23 (1) Notwithstanding any other provisions of this Paragraph, the Director shall, no later than 60 days 

24 after receipt of an application, notify the Federal Land Manager with the U.S. Department of 

25 Interior and U.S. Department of Agriculture of an application from a source or modification 

26 subject to this Rule; 

27 (2) When a source or modification may affect visibility of a Class I area the Director shall provide 

28 written notification to all affected Federal Land Managers within 30 days of receiving the permit 

29 application or within 30 days of receiving advance notification of an application. The notification 

30 shall be at least 30 days prior to the publication of notice for public comment on the application. 

31 The notification shall include a copy of all information relevant to the permit application including 

32 an analysis provided by the source of the potential impact of the proposed source on visibility; 

33 (3) The Director shall consider any analysis concerning visibility impairment performed by the 

34 Federal Land Manager if the analysis is received within 30 days of notification. If the Director 

35 finds that the analysis of the Federal Land Manager fails to demonstrate to his satisfaction that an 

36 adverse impact on visibility will result in the Class I area, the Director shall provide in the notice 

VI-16 A-66
Appendix A 

Draft – 10/9/2012 5 

1 of public hearing on the application, an explanation of his decision or notice as to where the 

2 explanation can be obtained; and 

3 (4) The Director may require monitoring of visibility in or around any Class I area by the proposed 

4 new source or modification when the visibility impact analysis indicates possible visibility 

5 impairment. 

6 (u) If the owner or operator of a source is using projected actual emissions to avoid applicability of prevention of 

7 significant deterioration requirements, the owner or operator shall notify the Director of the modification before 

8 beginning actual construction. The notification shall include: 

9 (1) a description of the project; 

10 (2) identification of sources whose emissions could be affected by the project; 

11 (3) the calculated projected actual emissions and an explanation of how the projected actual emissions 

12 were calculated, including identification of emissions excluded by 40 CFR 51.166(b)(40)(ii)(c); 

13 (4) the calculated baseline actual emissions and an explanation of how the baseline actual emissions 

14 were calculated; and 

15 (5) any netting calculations if applicable. 

16 If upon reviewing the notification, the Director finds that the project will cause a prevention of significant 

17 deterioration evaluation, then the Director shall notify the owner or operator of his findings. The owner or operator 

18 shall not make the modification until it has received a permit issued pursuant to this Rule. If a permit revision is not 

19 required pursuant to this rule, the owner or operator shall maintain records of annual emissions in tons per year, on a 

20 calendar year basis related to the modifications for 10 years following resumption of regular operations after the 

21 change if the project involves increasing the emissions unit's design capacity or its potential to emit the regulated 

22 NSR pollutant; otherwise these records shall be maintained for five years following resumption of regular operations 

23 after the change. The owner or operator shall submit a report to the director within 60 days after the end of each year 

24 during which these records must be generated. The report shall contain the items listed in 40 CFR 51.166(r)(6)(v)(a) 

25 through (c). The owner or operator shall make the information documented and maintained under this Paragraph 

26 available to the Director or the general public pursuant to the requirements in 40 CFR 70.4(b)(3)(viii). 

27 (v) The references to the Code of Federal Regulations (CFR) in this Rule are incorporated by reference unless a 

28 specific reference states otherwise. The version of the CFR incorporated in this Rule is that as of May 16, 2008 

29 October 20, 2010 at http://www.gpo.gov/fdsys/pkg/FR-2010-10-20/pdf/2010-25132.pdf and does not include any 

30 subsequent amendments or editions to the referenced material. 

31

32 History Note: Authority G.S. 143-215.3(a)(1); 143-215.107(a)(3); 143-215.107(a)(5); 143-215.107(a)(7); 143-

33 215.108(b); 150B-21.6; 

34 Eff. June 1, 1981; 

35 Amended Eff. December 1, 1992; August 1, 1991; October 1, 1989; July 1, 1988; October 1, 

36 1987; June 1, 1985; January 1, 1985; February 1, 1983; 

37 Temporary Amendment Eff. March 8, 1994, for a period of 180 days or until the permanent rule is 

38 effective, whichever is sooner; 

39 Amended Eff. ; January 2, 2011; September 1, 2010; May 1, 2008; July 28, 2006; July 

40 1, 1997; February 1, 1995; July 1, 1994. 

VI-17 A-67
Appendix A 

Draft – 10/9/2012 6 

1

2 15A NCA 02D .0531 is proposed for amendment as follows: 

3

4 15A NCAC 02D .0531 SOURCES IN NONATTAINMENT AREAS 

5 (a) For the purpose of this Rule the definitions contained in 40 CFR 51.165(a)(1) and 40 CFR 51.301 apply except 

6 the definition of "baseline actual emissions." For the purposes of this Rule: 

7 (1) "Baseline actual emissions" means the rate of emissions, in tons per year, of a regulated new 

8 source review (NSR) pollutant, as determined in accordance with Parts (A) through (C) of this 

9 Subparagraph: 

10 (A) For an existing emissions unit, baseline actual emissions means the average rate, in tons 

11 per year, at which the emissions unit actually emitted the pollutant during any 

12 consecutive 24-month period selected by the owner or operator within the 5-year period 

13 immediately preceding the date that a complete permit application is received by the 

14 Division for a permit required under this Rule. The Director shall allow a different time 

15 period, not to exceed 10 years immediately preceding the date that a complete permit 

16 application is received by the Division, if the owner or operator demonstrates that it is 

17 more representative of normal source operation. For the purpose of determining baseline 

18 actual emissions, the following apply: 

19 (i) The average rate shall include fugitive emissions to the extent quantifiable, and 

20 emissions associated with startups, shutdowns, and malfunctions; 

21 (ii) The average rate shall be adjusted downward to exclude any non-compliant 

22 emissions that occurred while the source was operating above any emission 

23 limitation that was legally enforceable during the consecutive 24-month period; 

24 (iii) For an existing emission unit (other than an electric utility steam generating 

25 unit), the average rate shall be adjusted downward to exclude any emissions that 

26 would have exceeded an emission limitation with which the major stationary 

27 source must currently comply. However, if the State has taken credit in an 

28 attainment demonstration or maintenance plan consistent with the requirements 

29 of 40 CFR 51.165(a)(3)(ii)(G) for an emission limitation that is part of a 

30 maximum achievable control technology standard that the Administrator 

31 proposed or promulgated under part 63 of the Code of Federal Regulations, the 

32 baseline actual emissions shall be adjusted to account for such emission 

33 reductions; 

34 (iv) For an electric utility steam generating unit, the average rate shall be adjusted 

35 downward to reflect any emissions reductions under G.S. 143-215.107D and for 

36 which cost recovery is sought pursuant to G.S. 62-133.6; 

VI-18 A-68
Appendix A 

Draft – 10/9/2012 7 

1 (v) For a regulated NSR pollutant, when a project involves multiple emissions units, 

2 only one consecutive 24-month period shall be used to determine the baseline 

3 actual emissions for all the emissions units being changed. A different 

4 consecutive 24-month period for each regulated NSR pollutant; and 

5 (vi) The average rate shall not be based on any consecutive 24-month period for 

6 which there is inadequate information for determining annual emissions, in tons 

7 per year, and for adjusting this amount if required by Subparts (ii) and (iii) of 

8 this Part; 

9 (B) For a new emissions unit, the baseline actual emissions for purposes of determining the 

10 emissions increase that will result from the initial construction and operation of such unit 

11 shall equal zero; and thereafter, for all other purposes, shall equal the unit's potential to 

12 emit; and 

13 (C) For a plantwide applicability limit (PAL) for a stationary source, the baseline actual 

14 emissions shall be calculated for existing emissions units in accordance with the 

15 procedures contained in Part (A) of this Subparagraph, and for a new emissions unit in 

16 accordance with the procedures contained in Part (B) of this Subparagraph; 

17 (2) In the definition of "net emissions increase," the reasonable period specified in 40 CFR 

18 51.165(a)(1)(vi)(C)(1) is seven years; and 

19 (3) Particulate matter PM2.5 significant levels in 40 CFR 51.165(a)(1)(x)(A) are incorporated by 

20 reference except as otherwise provided in this Rule. A net emission increase or the potential of a 

21 source to emit nitrogen oxide emissions shall be significant if the rate of emissions would equal or 

22 exceed 140 tpy. Sulfur dioxide and nitrogen oxides are precursor to PM2.5 in all nonattainment 

23 areas. Volatile organic compounds and ammonia are not significant precursors to PM2.5. 

24 (b) Redesignation to Attainment. If any county or part of a county to which this Rule applies is later designated in 

25 40 CFR 81.334 as attainment, all sources in that county subject to this Rule before the redesignation date shall 

26 continue to comply with this Rule. 

27 (c) Applicability. 40 CFR 51.165(a)(2) is incorporated by reference. This Rule applies to areas designated as 

28 nonattainment in 40 CFR 81.334, including any subsequent amendments or editions. 

29 (d) This Rule is not applicable to: 

30 (1) complex sources of air pollution regulated only under Section .0800 of this Subchapter and not 

31 under any other rule in this Subchapter; 

32 (2) emission of pollutants at the new major stationary source or major modification located in the 

33 nonattainment area that are pollutants other than the pollutant or pollutants for which the area is 

34 nonattainment. (A major stationary source or major modification that is major for volatile organic 

35 compounds or nitrogen oxides is also major for ozone.); 

36 (3) emission of pollutants for which the source or modification is not major; 

VI-19 A-69
Appendix A 

Draft – 10/9/2012 8 

1 (4) a new source or modification that qualifies for exemption under the provision of 40 CFR 

2 51.165(a)(4); or 

3 (5) emission of compounds listed under 40 CFR 51.100(s) as having been determined to have 

4 negligible photochemical reactivity except carbon monoxide. 

5 (e) 15A NCAC 02Q .0102 and .0302 are not applicable to any source to which this Rule applies. The owner or 

6 operator of the source shall apply for and receive a permit as required in 15A NCAC 02Q .0300 or .0500. 

7 (f) To issue a permit to a source to which this Rule applies, the Director shall determine that the source meets the 

8 following requirements: 

9 (1) The new major stationary source or major modification will emit the nonattainment pollutant at a 

10 rate no more than the lowest achievable emission rate; 

11 (2) The owner or operator of the proposed new major stationary source or major modification has 

12 demonstrated that all major stationary sources in the State that are owned or operated by this 

13 person (or any entity controlling, controlled by, or under common control with this person) are 

14 subject to emission limitations and are in compliance, or on a schedule for compliance that is 

15 federally enforceable or contained in a court decree, with all applicable emission limitations and 

16 standards of this Subchapter that EPA has authority to approve as elements of the North Carolina 

17 State Implementation Plan for Air Quality; 

18 (3) The owner or operator of the proposed new major stationary source or major modification will 

19 obtain sufficient emission reductions of the nonattainment pollutant from other sources in the 

20 nonattainment area so that the emissions from the new major source and associated new minor 

21 sources will be less than the emissions reductions by a ratio of at least 1.00 to 1.15 for volatile 

22 organic compounds and nitrogen oxides and by a ratio of less than one to one for carbon 

23 monoxide. The baseline for this emission offset shall be the actual emissions of the source from 

24 which offset credit is obtained. Emission reductions shall not include any reductions resulting 

25 from compliance (or scheduled compliance) with applicable rules in effect before the application. 

26 The difference between the emissions from the new major source and associated new minor 

27 sources of carbon monoxide and the emission reductions shall be sufficient to represent reasonable 

28 further progress toward attaining the National Ambient Air Quality Standards. The emissions 

29 reduction credits shall also conform to the provisions of 40 CFR 51.165(a)(3)(ii)(A) through (G) 

30 and (J); and 

31 (4) The North Carolina State Implementation Plan for Air Quality is being carried out for the 

32 nonattainment area in which the proposed source is located. 

33 (g) New natural gas-fired electrical utility generating units for which cost recovery is sought pursuant to G. S. 62-

34 133.6 shall install lowest achievable emission rate technology for NOX and SO2, regardless of the applicability of the 

35 rest of this Rule. 

36 (h) 40 CFR 51.165(f) is incorporated by reference except that 40 CFR 51.165(f)(10)(iv)(A) is changed to read: "If 

37 the emissions level calculated in accordance with Paragraph (f)(6) of this Section is equal to or greater than 80 

VI-20 A-70
Appendix A 

Draft – 10/9/2012 9 

1 percent of the PAL level, the Director shall renew the PAL at the same level." 40 CFR 51.165(f)(10)(iv)(B) is not 

2 incorporated by reference. 

3 (i) When a particular source or modification becomes a major stationary source or major modification solely by 

4 virtue of a relaxation in any enforceable limitation established after August 7, 1980, on the capacity of the source or 

5 modification to emit a pollutant, such as a restriction on hours of operation, then the provisions of this Rule shall 

6 apply to the source or modification as though construction had not yet begun on the source or modification. 

7 (j) To issue a permit to a source of a nonattainment pollutant, the Director shall determine, in accordance with 

8 Section 173(a)(5) of the Clean Air Act and in addition to the other requirements of this Rule, that an analysis 

9 (produced by the permit applicant) of alternative sites, sizes, production processes, and environmental control 

10 techniques for the source demonstrates that the benefits of the source significantly outweigh the environmental and 

11 social costs imposed as a result of its location, construction, or modification. 

12 (k) The provisions of 40 CFR 52.21(r)(2) regarding the period of validity of approval to construct are incorporated 

13 by reference except that the term "Administrator" is replaced with "Director". 

14 (l) Approval of an application regarding the requirements of this Rule does not relieve the owner or operator of the 

15 responsibility to comply with applicable provisions of other rules of this Chapter and any other requirements under 

16 local, state, or federal law. 

17 (m) Except as provided in 40 CFR 52.28(c)(6), for a source or modification subject to this Rule the following 

18 procedures shall be followed: 

19 (1) Notwithstanding any other provisions of this Paragraph, the Director shall, no later than 60 days 

20 after receipt of an application, notify the Federal Land Manager with the U.S. Department of 

21 Interior and U.S. Department of Agriculture of an application from a source or modification 

22 subject to this Rule; 

23 (2) The owner or operator of the source shall provide an analysis of the impairment to visibility that 

24 would occur because of the source or modification and general commercial, industrial and other 

25 growth associated with the source or modification; 

26 (3) When a source or modification may affect the visibility of a Class I area the Director shall provide 

27 written notification to all affected Federal Land Managers within 30 days of receiving the permit 

28 application or within 30 days of receiving advance notification of an application. The notification 

29 shall be at least 30 days before the publication of the notice for public comment on the application. 

30 The notification shall include a copy of all information relevant to the permit application including 

31 an analysis provided by the source of the potential impact of the proposed source on visibility; 

32 (4) The Director shall consider any analysis concerning visibility impairment performed by the 

33 Federal Land Manager if the analysis is received within 30 days of notification. If the Director 

34 finds that the analysis of the Federal Land Manager fails to demonstrate to his satisfaction that an 

35 adverse impact on visibility will result in the Class I area, the Director shall provide in the notice 

36 of public hearing on the application, an explanation of his decision or notice where the explanation 

37 can be obtained; 

VI-21 A-71
Appendix A 

Draft – 10/9/2012 10 

1 (5) The Director shall issue permits only to those sources whose emissions will be consistent with 

2 making reasonable progress, as defined in Section 169A of the Clean Air Act, toward the national 

3 goal of preventing any future, and remedying any existing, impairment of visibility in mandatory 

4 Class I areas when the impairment results from manmade air pollution. In making the decision to 

5 issue a permit, the Director shall consider the cost of compliance, the time necessary for 

6 compliance, the energy and nonair quality environmental impacts of compliance, and the useful 

7 life of the source; and 

8 (6) The Director may require monitoring of visibility in or around any Class I area by the proposed 

9 new source or modification when the visibility impact analysis indicates possible visibility 

10 impairment. 

11 The requirements of this Paragraph do not apply to nonprofit health or nonprofit educational institutions. 

12 (n) If the owner or operator of a source is using projected actual emissions to avoid applicability of nonattainment 

13 new source review, the owner or operator shall notify the director of the modification before beginning actual 

14 construction. The notification shall include: 

15 (1) a description of the project; 

16 (2) identification of sources whose emissions could be affected by the project; 

17 (3) the calculated projected actual emissions and an explanation of how the projected actual emissions 

18 were calculated, including identification of emissions excluded by 40 CFR 

19 51.165(a)(1)(xxviii)(B)(3); 

20 (4) the calculated baseline actual emissions and an explanation of how the baseline actual emissions 

21 were calculated; and 

22 (5) any netting calculations if applicable. 

23 If upon reviewing the notification, the Director finds that the project will cause a nonattainment new source review 

24 evaluation, then the Director shall notify the owner or operator of his findings. The owner or operator shall not make 

25 the modification until it has received a permit issued pursuant to this Rule. If a permit revision is not required 

26 pursuant to this Rule, the owner or operator shall maintain records of annual emissions in tons per year on a calendar 

27 year basis related to the modifications for 10 years following resumption of regular operations after the change if the 

28 project involves increasing the emissions unit's design capacity or its potential to emit the regulated NSR pollutant; 

29 otherwise these records shall be maintained for five years following resumption of regular operations after the 

30 change. The owner or operator shall submit a report to the director within 60 days after the end of each year during 

31 which these records must be generated. The report shall contain the items listed in 40 CFR 51.165(a)(6)(v)(A) 

32 through (C). The owner or operator shall make the information documented and maintained under this Paragraph 

33 available to the Director or the general public pursuant to the requirements in 40 CFR 70.4(b)(3)(viii). 

34 (o) The reference to the Code of Federal Regulations (CFR) in this Rule are incorporated by reference unless a 

35 specific reference states otherwise. Except for 40 CFR 81.334, the version of the CFR incorporated in this Rule is 

36 that as of May 16, 2008 and does not include any subsequent amendments or editions to the referenced material. 

37 

VI-22 A-72
Appendix A 

Draft – 10/9/2012 11 

1 History Note: Authority G.S. 143-215.3(a)(1); 143-215.107(a)(5); 143-215.108(b); 

2 Eff. June 1, 1981; 

3 Amended Eff. December 1, 1993; December 1, 1992; August 1, 1991; December 1, 1989; October 

4 1, 1989; July 1, 1988; October 1, 1987; June 1, 1985; January 1, 1985; February 1, 1983; 

5 Temporary Amendment Eff. March 8, 1994 for a period of 180 days or until the permanent rule is 

6 effective, whichever is sooner; 

7 Amended Eff. ; January 2, 2011; September 1, 2010; May 1, 2008; May 1, 2005; July 1, 

8 1998; July 1, 1996; July 1, 1995; July 1, 1994.

VI-23 A-73
ADDENDUM TO 

APPROVED ECONOMIC ANALYSIS 

Rule Citation Number: 15A NCAC 02D .0530, Prevention of Significant Deterioration 

 15A NCAC 02D .0531 Sources in Nonattainment Areas 

Rule Topic: Revisions to New Source Review and Prevention of Significant Deterioration (PSD) 

Nitrogen Oxides (NOx) Significance Level for PM2.5 (512) and PM2.5 Increment (516)

DENR Division: Division of Air Quality 

Agency Contact: Joelle Burleson, Rule Development Branch Supervisor 

 Division of Air Quality (DAQ) 

(919) 707-8720 

Joelle.Burleson@ncdenr.gov

Initial OSBM approval: 

October 10, 2012 

http://www.osbm.state.nc.us/files/pdf_files/DENR10102012.pdf 

Reason for Addendum: 

During the public comment period, there were two court decisions that were issued on the 

implementation of fine particulate (PM2.5) regulations. The first court decision was the U.S. 

Court of Appeals for the District of Columbia Circuit, January 4, 2013, Sierra Club vs. United 

States Environmental Protection Agency (EPA), No. 08-1250. The court reviewed the PM2.5

Implementation Rule, 72 FR 20586 (4/25/2007) and PM2.5 NSR Implementation Rule, 73 FR 

28321 (5/16/2008). The petitioners challenged EPA’s decision to promulgate its PM2.5 

implementation rules pursuant to Subpart 1 of Part D of Title I which contains the 

implementation provisions for nonattainment areas in general rather than Subpart 4 of Part D of 

Title I which contains implementation provisions specific to PM10. The court decision remanded 

the two implementation rules to EPA to repromulgate them pursuant to Subpart 4 of Part D of 

Title I of the Clean Air Act. 

The second court decision was the U.S Court of Appeals for the District of Columbia Circuit, 

January 22, 2013, National Resources Defense Council and Sierra Club vs. EPA, No. 10-1413. 

The court reviewed of the PM2.5 Increments, Significant Impact Levels (SIL) and Significant 

Monitoring Concentration (SMC) final rule in 75 FR 64864 (October 20, 2010). Specifically, the 

court reviewed the adoption of the SIL and SMC screening tools EPA uses to determine whether 

a new source may be exempted from certain requirements under 40 CFR 51.165, Permit 

requirements. 

The SILs sets a de minimis ambient impact where a source’s impact that is below a SIL is not 

required to conduct more extensive modeling to demonstrate its emission will not contribute to a 

violation of the national ambient air quality standard (NAAQS). The SMC sets a de minimis 

VI-24 A-74
concentration where a source can show through modeling that its impacts are less than the SMC, 

eliminating the requirement to collect additional monitoring data. The court decision vacated and 

remanded the SILs under 51.166(k)(2) and §52.21(k)(2) for further consideration by EPA. The 

decision also vacated the parts of the rule establishing the SMCs due to EPA exceeding its 

statutory authority. 

Rule Changes: 

Rule 15A NCAC 02D .0530 was amended to remove the incorporation by reference date of 

October 20, 2010 and keep the prehearing May 16, 2008 incorporation by reference date. DAQ 

also explicitly added the new PM2.5 and existing PM10 increments as indicators of particulate 

matter in Paragraph (v) of Rule 15A NCAC 02D .0530. Note, the PM10 increments are part of the 

EPA’s regulation dated May 16, 2008, and as a result were already part of the state rule through 

the incorporation by reference of the May 16, 2008 regulation. Therefore the inclusion of the 

PM10 increments in the rule does not constitute a new requirement. 

Change to OSBM approved fiscal note: 

The increments are not changed from the initial proposal. Instead of incorporating the increments 

by reference, the increments are written into the body of the rule. Therefore there is no change to 

the calculated fiscal impact due to adding the increment language to the rule. 

The significant impact levels (SILs) and significant monitoring concentration (SMC) were 

incorporated by reference in the proposed rule. Due to the court decision to vacate the SILs and 

SMC in EPA’s PM2.5 implementation rule, the SILs and SMC were removed from the proposed 

rule by changing the incorporation date to the prehearing May 16, 2008. The SIL is a screening 

tool that EPA developed to evaluate the impact of new facilities and major modifications on the 

PM2.5 NAAQS and PSD increments. A facility can avoid a full impact increment analysis if its 

emissions are below the SIL. In the fiscal note that was approved for the proposed rules that went 

to public hearing, it was assumed that all affected facilities were above the SILs. The fiscal 

analysis assumed that SILs would not be used when the total cost for adding a PM2.5 increment 

analysis to each PSD permit application was calculated. It was also determined in the fiscal note 

that there was no impact due to adding the SMC to the proposed rule. 

The removal of the SIL and SMC provisions from the rule does not affect the original fiscal 

impacts calculated in Section III, Costs and Benefits by Affected Party, for state government and 

the private sector to incorporate the federal PM2.5 increments into the state PSD program 

VI-25 A-75
United States Court of Appeals

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued October 17, 2012 Decided January 4, 2013

No. 08-1250

NATURAL RESOURCES DEFENSE COUNCIL AND SIERRA CLUB,

PETITIONERS

v.

ENVIRONMENTAL PROTECTION AGENCY,

RESPONDENT

FINE PARTICULATE LITIGATION GROUP ET AL.,

INTERVENORS

Consolidated with 09-1102, 11-1430

On Petitions for Review of Final Rules of the 

United States Environmental Protection Agency

Paul Cort argued the cause for the petitioners. Tim D.

Ballo and David S. Baron entered appearances.

Brian H. Lynk, Attorney, United States Department of

Justice, argued the cause for the respondent. Geoffrey L.

Wilcox and Stephanie L. Hogan, Attorneys, United States

Environmental Protection Agency, were on brief.

Charles H. Knauss, Shannon S. Broome, Robert T. Smith,

Denise W. Kennedy, John A. Bryson, Emily C. Schilling,

VI-26 A-76
2

Leslie S. Ritts, Norman W. Fichthorn, Lauren E. Freeman,

Lucinda Minton Langworthy and Lorane F. Hebert were on

brief for the intervenors. Michelle M. Schoeppe entered an

appearance.

Before: HENDERSON and TATEL, Circuit Judges, and

WILLIAMS, Senior Circuit Judge.

Opinion for the Court filed by Circuit Judge HENDERSON.

KAREN LECRAFT HENDERSON, Circuit Judge: The four

petitioners seek review of two final rules, promulgated 1

pursuant to the Clean Air Act (CAA, Act), which govern

implementation of the national ambient air quality standard

(NAAQS) for “fine” particulate matter—that is, particulate

matter (PM) having a diameter equal to or less than 2.5 2

micrometers (PM ). 2.5 See Final Clean Air Fine Particle

Implementation Rule, 72 Fed. Reg. 20,586 (Apr. 25, 2007)

2.5 (PM Implementation Rule); Implementation of the New

Source Review (NSR) Program for Particulate Matter Less

Than 2.5 Micrometers (PM ), 73 Fed. Reg. 28,321 (May 16, 2.5

2008) (PM NSR Implementation Rule) (collectively, Final 2.5

They include the Natural Resources Defense Council, Sierra 1

Club, American Lung Association and Medical Advocates for Healthy

Air.

“Particulate matter is the generic term for a broad class of 2

chemically and physically diverse substances that exist as discrete

particles (liquid droplets or solids) over a wide range of sizes.” The

particles “originate from a variety of anthropogenic stationary and

mobile sources as well as from natural sources” and “may be emitted

directly or formed in the atmosphere by transformations of gaseous

emissions such as sulfur oxides (SO ), nitrogen oxides (NO ), and x x

volatile organic compounds (VOC).” National Ambient Air Quality

Standards for Particulate Matter, 62 Fed. Reg. 38,652, 38,653 (July

18, 1997).

VI-27 A-77
3

PM Implementation Rules). In particular, the petitioners 2.5

3

challenge the decision of the Environmental Protection

Agency (EPA) to promulgate the Final PM Implementation 2.5

Rules pursuant to the general implementation provisions of

Subpart 1 of Part D of Title I of the Act, 42 U.S.C. §§ 7501-

7509a (Subpart 1), rather than the particulate-matter-specific

provisions of Subpart 4 of Part D of Title I, id. §§ 7513-7513b

(Subpart 4). We agree with the petitioners that EPA erred in

applying the provisions of Subpart 1 rather than Subpart 4.

I.

Section 109 of the Act mandates that EPA establish a

primary NAAQS for each air pollutant for which EPA has

issued “air quality criteria” under CAA section 108. 42

U.S.C. § 7409(a)(1). The Act defines each such NAAQS as 4

that standard “the attainment and maintenance of which in the

judgment of the Administrator, based on such criteria and

allowing an adequate margin of safety, are requisite to protect

the public health.” Id. § 7409(b)(1). EPA is required to

“complete a thorough review” of each pollutant’s standard

and air quality criteria “at five-year intervals” and “make such

revisions in such criteria and standards and promulgate such

new standards as may be appropriate.” Id. § 7409(d)(1). 

Once a NAAQS has been established, each state must adopt

Under the Act’s NSR provisions, new or modified pollutant 3

sources must meet “strict standards,” while existing sources are

“ ‘grandfathered.’ ” New York v. U.S. EPA, 413 F.3d 3, 13 (D.C. Cir.

2005).

The Act also requires EPA to promulgate a secondary standard, 4

“the attainment and maintenance of which . . . is requisite to protect

the public welfare from any known or anticipated adverse effects

associated with” the pollutant. 42 U.S.C. § 7409(b)(2). In this case,

EPA promulgated a single NAAQS as both the primary and the

secondary standard. 

VI-28 A-78
4

and submit to EPA for approval a State Implementation Plan

(SIP) that “provides for implementation, maintenance, and

enforcement of [the NAAQS] in each air quality control

region (or portion thereof) within such State.” Id.

§ 7410(a)(1). Each SIP must “include enforceable emission

limitations and other control measures, means, or techniques 

. . . , as well as schedules and timetables for compliance, as

may be necessary or appropriate to meet the [CAA’s]

applicable requirements.” Id. § 7410(a)(2)(A).

 Part D of CAA Title I governs “Plan Requirements for

Nonattainment Areas” (that is, areas that have not attained

compliance with the applicable NAAQS) and Subpart 1

thereof, added to the Act in 1977, addresses “Nonattainment

Areas in General.” Subpart 1 provides generally that, once

EPA designates an area as “nonattainment,” it “may classify

the area” so as to establish an attainment deadline and it must

establish a schedule for the state encompassing the

nonattainment area to submit a SIP. Id. § 7502(a)(1)(A). The

SIP, in turn, is required, inter alia, to (1) provide for

implementation of control measures, (2) inventory existing

emissions, (3) identify and quantify pollutant emissions

permissible under the SIP from the construction and operation

of all major new stationary emission sources, (4) require NSR

permits for such construction and operation and (5) establish

compliance schedules and timetables. Id. § 7502(c). Pursuant

to this regime, in 1971, EPA established a particulate matter

NAAQS applicable to “Total Suspended Particles,” i.e.,

particulate matter up to 25-45 micrometers in diameter.

In 1987, EPA revised the NAAQS to apply only to

particles equal to or smaller than 10 micrometers (PM )—a 10

“size-specific indicator” it determined “represent[ed] those

particles small enough to penetrate to the thoracic region”

because “[t]he risks of adverse health effects associated with

deposition of typical ambient fine and coarse particles in the

VI-29 A-79
5

thorax (tracheobronchial and alveolar regions of the

respiratory tract) are markedly greater than those associated

with deposition in the extrathoracic (head) region.” Revisions

to the National Ambient Air Quality Standards for Particulate

Matter, 52 Fed. Reg. 24,634, 24,639 (July 1, 1987) (footnote

omitted) (1987 PM NAAQS Revisions). 

In 1990, the Congress amended CAA Part D by adding to

it Subparts 2 through 5, each of which contains additional

provisions governing nonattainment plan requirements for a

particular pollutant or group of pollutants. At issue here,

Subpart 4 applies to “Particulate Matter Nonattainment

Areas” and covers such matters as setting attainment dates for

PM nonattainment areas, classifying the nonattainment areas

(as “moderate” or “serious”), reclassifying them (e.g., upon

failure to attain) and extending attainment dates. 42 U.S.C.

§§ 7513-7513b; see also id. §§ 7511-7511f (ozone-specific

requirements); id. §§ 7512-7512a (carbon monoxide-specific

requirements).

In 1997, EPA again revised the particulate matter

NAAQS, this time setting separate PM standards for fine 2.5

particles (having a diameter of 2.5 micrometers or less), while

10 retaining the existing PM standards. National Ambient Air

Quality Standards for Particulate Matter, 62 Fed. Reg. 38,652,

38,654 nn.5-6 (July 18, 1997) (Final PM NAAQS Rule). We

upheld the new particulate matter standards in 2002 after

remand from the United States Supreme Court. See Am.

Trucking Ass’ns v. EPA, 283 F.3d 355 (D.C. Cir. 2002)

(applying Whitman v. Am. Trucking Ass’ns, 531 U.S. 457

(2001)).

In 2005, EPA published its Proposed Rule To Implement

the Fine Particle National Ambient Air Quality Standards, 70

Fed. Reg. 65,984 (Nov. 1, 2005). EPA subsequently issued

the final fine particle implementation rule in two stages. In

2007, it published the PM Implementation Rule, setting out 2.5

VI-30 A-80
6

2.5 the general SIP requirements for PM . EPA followed up in

2008 with the PM NSR Implementation Rule to govern the 2.5

NSR permitting process. In each of the two Final PM2.5

Implementation Rules, EPA expressly followed the general

implementation provisions in Subpart 1 of Part D rather than

Subpart 4’s particulate-material-specific provisions. See

PM Implementation Rule, 72 Fed. Reg. at 20,589 (“EPA is 2.5

2.5 issuing this rule to implement the 1997 PM NAAQS in

accordance with the statutory requirements of the CAA set

forth in Subpart 1 of Part D of Title 1, i.e., sections 171-179B

of the Act. . . . EPA has concluded that Congress did not

intend the Agency to implement particulate matter NAAQS

other than those using PM as the indicator in accordance 10

with Subpart 4 of Part D of Title 1 . . . .”); PM NSR 2.5

Implementation Rule, 73 Fed. Reg. at 28,332 (“We do not

agree that subpart 4 of part D applies to PM nonattainment 2.5

areas. Subpart 4 was added to the Act by Congress

10 specifically to address the PM NAAQS. We believe that the

PM standard should be implemented under subpart 1 of part 2.5

D, which is the general provision of the Act related to

NAAQS implementation.”). The petitioners filed timely

petitions for review of both the PM Implementation Rule 2.5

and the PM NSR Implementation Rule. 2.5

II.

We review EPA’s interpretation of the CAA under

Chevron U.S.A. Inc. v. Natural Res. Def. Council, Inc., 467

U.S. 837 (1984). See Natural Res. Def. Council v. EPA, 489

F.3d 1250, 1257 (D.C. Cir. 2007). Under Chevron:

We first ask “whether Congress has directly spoken

to the precise question at issue,” in which case we

“must give effect to the unambiguously expressed

intent of Congress.” If the “statute is silent or

ambiguous with respect to the specific issue,”

however, we move to the second step and defer to

VI-31 A-81
7

the agency’s interpretation as long as it is “based on

a permissible construction of the statute.”

Id. (quoting Chevron, 467 U.S. at 842-43) (other quotation

marks omitted). Before addressing whether EPA correctly

applied Subpart 1 under the Chevron framework, we first

consider the timeliness of the petitioners’ instant challenge.

A.

EPA contends the petitioners’ challenge is untimely

because it should have been raised in 1997 when EPA issued

the Final PM NAAQS Rule, which, EPA maintains, set out its

final decision on Subpart 1’s applicability. Because we

conclude EPA did not take final reviewable action in 1997,

the petitioners’ challenge is timely.5

In urging that it finalized its decision in 1997, EPA relies

on two excerpts from the preamble to the 1997 Final PM

NAAQS Rule. First, EPA cites its response to comments

challenging its authority to promulgate a separate PM2.5

standard given that the 1990 amendments referred only to a

PM standard. At the conclusion of its response, EPA offered 10

the following defense of its authority to promulgate the new

PM standards, rooted in Subpart 1, couched in plainly 2.5

tentative language:

EPA’s analysis of its ability to implement a PM2.5

standard under the provisions of subpart 1 of Part D

of Title I does not support the view that Congress

prohibited EPA from promulgating such a standard. 

Congress clearly specified an approach to the

EPA acknowledges the instant petitions for review of the PM2.5

5

2.5 Implementation Rule and the PM NSR Implementation Rule were

timely filed within sixty days after each rule’s publication as required

under 42 U.S.C. § 7607(b)(1). See Br. of Resp’t 1.

VI-32 A-82
8

10 implementation of the PM standard in the

provisions of subpart 4 of Part D of Title I of the Act. 

The EPA believes that the clear and express linkage

of that approach to the PM standard indicates that a 10

different PM standard should be implemented under

the general principles of subpart 1 of Part D of Title I

of the Act. That Congress directed specifically how

EPA and the States 10 should implement the PM

standard does not carry with it the implication that

Congress intended to prohibit EPA from exercising

its otherwise clear and express authority to adopt a

PM standard based on a different metric . . . .

Final PM NAAQS Rule, 62 Fed. Reg. at 38,695 (emphases

added). Some pages later, in a footnote, EPA more

affirmatively, albeit summarily, stated its position that

implementation of the new standard need not and would not

be governed by Subpart 4: “The SIP requirements of subpart 4

of Part D of Title I of the Act apply to SIPs for areas

designated as not attaining NAAQS for PM . Those 10

2.5 requirements will not apply to SIPs to implement the PM

NAAQS.” Id. at 38,704 n.96. We conclude these two

unembellished snippets, buried in the preamble to the 1997

Final PM NAAQS Rule, did not constitute final agency action

so as to be reviewable in 1997.

 “A final agency action is one that marks the

consummation of the agency’s decisionmaking process and

that establishes rights and obligations or creates binding legal

consequences.” Natural Res. Def. Council v. EPA, 559 F.3d

561, 564 (D.C. Cir. 2009) (citing Bennett v. Spear, 520 U.S.

154, 177-78 (1997)). We have observed that “[w]hile

preamble statements,” such as those just quoted, “may in

some unique cases constitute binding, final agency action

susceptible to judicial review, this is not the norm.” Id. at

VI-33 A-83
9

564-65 (citations omitted). As this case is not a “unique” one,

we adhere to the norm.

The above quoted excerpts appear in a document

expressly intended to “describe[] EPA’s decision to revise the

national ambient air quality standards (NAAQS) for

particulate matter (PM),” Final PM NAAQS Rule, 62 Fed.

Reg. at 38,652 (emphasis added)—it did not purport to detail

how the revised standards should be implemented. Indeed,

EPA had earlier addressed the issue of implementation in a

separate Interim Implementation Policy on New or Revised

Ozone and Particulate Matter (PM) National Ambient Air

Quality Standards (NAAQS), 61 Fed. Reg. 65,752 (Dec. 13,

1996) (Interim Implementation Policy). Although the Interim

Implementation Policy likewise expressed an intent to apply

Subpart 1 to implement the PM standard, 61 Fed. Reg. at 2.5

65,753, it made clear that, as its name suggests, it was only a

temporary policy, which “would represent EPA’s preliminary

views” and “while it m[ight] include various statements that

States must take certain actions, these statements [we]re made

pursuant to EPA’s preliminary interpretations, and thus d[id]

not bind the States and public as a matter of law.” Id. at

65,752 (emphases added). Accordingly, “[o]nly after EPA

ha[d] made its interpretations final through rulemaking”—

“follow[ing] the requirements of the Administrative

Procedure Act, 5 U.S.C. section 553(b) and (c)”—“will they

be binding on the States and public as a matter of law.” Id. 

Given EPA’s expressed intent to issue a final, binding noticeand-comment rule on the issue—to supplant its “preliminary”

policies—we do not see how the quoted lines from the

preamble to the 1997 rule revising the standard itself “mark

the consummation of the agency’s decisionmaking process”

on how to implement the standard so as to constitute final

agency action. Bennett v. Spear, 520 U.S. at 177-78 (internal

quotation marks omitted). Instead, we conclude EPA

consummated the decisionmaking process to implement the

VI-34 A-84
10

PM standard only when it published its final views in the 2.5

2.5 two Final PM Implementation Rules now under review. 

Notwithstanding its express and indefinite deferral of a final

implementation policy in 1997, EPA argues the Supreme

Court’s decision in Whitman v. American Trucking

Associations, 531 U.S. 457 (2001), requires us to hold

otherwise. We are not so persuaded. 

In Whitman, the Supreme Court reviewed EPA’s decision

to implement its “8-hour” 0.08 ppm NAAQS for ozone—

which replaced the previous 1-hour ozone standard of 0.12

ppm—under Subpart 1’s general nonattainment area

provisions rather than under Subpart 2’s ozone-specific

provisions added in 1990. See National Ambient Air Quality

Standards for Ozone, 62 Fed. Reg. 38,856, 38,873 (July 18,

1997) (Final Ozone NAAQS Rule) (“[T]he provisions of

subpart 1 of part D of Title I of the Act would apply to the

3

implementation of the new 8-hour O standards.”). The Court

concluded that, in the main, the new ozone NAAQS should be

implemented pursuant to Subpart 2 notwithstanding Subpart 2

was enacted to address the former 1-hour standard and some

provisions might therefore be “ill fitted to implementation of

the revised standard” and thus leave “gaps” for EPA to fill

under Chevron step 2. Whitman, 531 U.S. at 483-84. The

Whitman Court first addressed the threshold question whether

Subpart 1 constituted final agency action subject to review

and concluded that it did. See id. at 477-78. 

Addressing the Interim Implementation Policy, which

covered both the ozone and the particulate matter standards,

the Whitman Court acknowledged: “If the EPA had done no

more, we perhaps could accept its current claim that its action

was not final.” Id. at 477. The Court explained, however,

that, vis-à-vis the ozone standard, EPA had done “more.” 

After the White House issued a “ ‘Memorandum for the

Administrator of the Environmental Protection Agency’ that

VI-35 A-85
11

prescribed implementation procedures for the EPA to follow,”

EPA “supplemented this memorandum with an explanation of

the implementation procedures.” Id.; see Implementation of

Revised Air Quality Standards for Ozone and Particulate

Matter, 62 Fed. Reg. 38,421, 38,422 (July 18, 1997)

(Memorandum of July 16, 1997); Implementation Plan for

Revised Air Quality Standards, 62 Fed. Reg. 38,423

(Implementation Memorandum Supplement). In a section of

the Implementation Memorandum Supplement titled

“Implementation of Ozone Standard,” EPA explained that,

after receiving comments on the proposed Interim

Implementation Policy, it had “reconsidered” its interpretation

in part and determined that “Subpart 2 should continue to

apply as a matter of law for the purpose of achieving

attainment of the current 1-hour standard.” Id. at 38,424. But

EPA made clear it adhered to its previously expressed view

that “[o]nce an area attains the 1-hour standard, those

provisions will no longer apply and the area’s implementation

of the new 8-hour standard would be governed only by the

provisions of Subpart 1 of Part D of Title I.” Id. EPA

subsequently “published [this interpretation] in the

explanatory preamble to its final ozone NAAQS under the

heading, ‘Final decision on the primary standard.’ ” 

Whitman, 531 U.S. at 477-78 (citing Final Ozone NAAQS

Rule, 62 Fed. Reg. at 38,873). Based on this chronology, the

Supreme Court found EPA’s ozone implementation policy

was final and reviewable, explaining:

The EPA’s “decisionmaking process,” which began

with the 1996 proposal and continued with the

reception of public comments, concluded when the

agency, “in light of [these comments],” and in

conjunction with a corresponding directive from the

White House, adopted the interpretation of Part D at

issue here. Since that interpretation issued, the EPA

has refused in subsequent rulemakings to reconsider

VI-36 A-86
12

it, explaining to disappointed commenters that its

earlier decision was conclusive. 

Whitman, 531 U.S. at 478-79 (citing 63 Fed. Reg. 31,014,

31,018-19 (1998)). The history of the PM standard reveals 2.5

no comparable decisionmaking process regarding

implementation. The Implementation Memorandum

Supplement did not even mention Subpart 1 or Subpart 4 in its

discussion of the PM implementation—much less 2.5

distinguish between them or discuss their applicability vel non

2.5 to implementation of the PM standard. See 62 Fed. Reg. at

38,427-29 (section titled “Implementation of New PM2.5

NAAQS”). Nor did EPA thereafter overtly treat its “interim”

PM implementation policy as final when it promulgated the 2.5

2007 and 2008 Final PM Implementation Rules challenged 2.5

here. Accordingly, we conclude the petitioners’ challenge is

timely and proceed to EPA’s substantive decision to

implement the NAAQS under Subpart 1.

B.

EPA contends that because Subpart 4 repeatedly refers to

PM —rather than to PM or “particulate matter” 10 2.5

generally—the statutory language limits Subpart 4’s

applicability to implementation of the current PM standard. 10

Thus, by default, EPA contends, PM must be implemented 2.5

pursuant to the general (and less stringent ) implementation 6

For example, (1) Subpart 4 requires a nonattainment area to be 6

classified as “moderate” and upon failure to attain to be reclassified as

“serious,” 42 U.S.C. § 7513(a)-(c), while under Subpart 1, EPA “may”

but is not required to classify a nonattainment area, id.

§ 7502(a)(1)(A); (2) under Subpart 4, a “serious” attainment date may

be extended only once (for a maximum of 5 years) and only if the SIP

includes the “most stringent measures” included in any state’s SIP or

achieved in any State and feasible for the area, id. § 7513(e), while

Subpart 1 allows attainment date extensions of up to 10 years with no

VI-37 A-87
13

procedure in Subpart 1. This argument ignores the plain

meaning of the statute and the lesson of Whitman.

Before the Congress enacted Subpart 4, EPA had

promulgated a single particulate matter standard—the PM10

standard—which encompassed all particulate matter with a

diameter of 10 micrometers or less—including both coarse

and fine particulate matter, that is, particulate matter now

governed by both the PM and PM standards—and the 10 2.5

1990 CAA amendments adopted this broad meaning in

defining “PM .” 1987 PM NAAQS Revisions, 52 Fed. Reg. 10

at 24,639 (“The Administrator . . . has decided to replace

[Total Suspended Particles] as the particle indicator for the

primary standards with a new indicator that includes only

those particles less than a nominal 10 [micrometers] in

diameter. . . . In defining the standards for particulate matter,

10 this new indicator is termed PM .”); 42 U.S.C. § 7602(t)

(“The term ‘PM-10’ means particulate matter with an

aerodynamic diameter less than or equal to a nominal ten

micrometers . . . .”). Thus, by its express terms, Subpart 4,

when enacted, governed all PM particles, including those 10

now denominated PM . The scope of the statutory 2.5

definition—and consequently of Subpart 4’s application—did

not change when EPA subdivided PM by regulation. As the 10

“stringent measures” requirement therefor, id. § 7502(a)(2)(A); (3)

Subpart 4 subjects a “serious” nonattainment area that fails to timely

attain to a mandatory annual 5% pollutant reduction, id. § 7513a(d),

while Subpart 1 includes no such requirement; (4) Subpart 4 requires

that “reasonable available control measures” must be implemented

within 4 years after designation, id. § 7513a(a)(1)(C), while Subpart

1 requires such measures be implemented “as expeditiously as

practicable,” id. § 7502(c)(1); and (5) Subpart 4 requires that best

available control measures be implemented no later than 4 years after

an area is classified or reclassified as “serious,” id. § 7513a(b)(1)(B),

while Subpart 1 has no best available control measures requirement.

VI-38 A-88
14

Whitman Court made clear, the intent of the 1990

amendments was to limit the broad implementation discretion

Subpart 1 had previously granted EPA. Cf. Whitman, 531

U.S. at 484 (“The principal distinction between Subpart 1 and

Subpart 2 is that the latter eliminates regulatory discretion

that the former allowed.”). It makes no sense then that the

Congress would have wanted EPA to relax Subpart 4’s more

stringent, nondiscretionary requirements for implementing

2.5 the PM standard at the same time EPA decided to

2.5 strengthen the PM standard itself based on “evidence from

numerous health studies demonstrating that serious health

effects are associated with exposures to elevated levels of

PM .” PM Implementation Rule, 72 Fed. Reg. at 20,586; 2.5 2.5

see also id. at 20,586-87 (“Epidemiological studies have

shown statistically significant correlations between elevated

PM levels and premature mortality. Other important effects 2.5

associated with PM exposure include aggravation of 2.5

respiratory and cardiovascular disease (as indicated by

increased hospital admissions, emergency room visits,

absences from school or work, and restricted activity days),

changes in lung function and increased respiratory symptoms,

as well as new evidence for more subtle indicators of

cardiovascular health. Individuals particularly sensitive to

PM exposure include older adults, people with heart and 2.5

lung disease, and children.”). Notwithstanding the plain 7

The regulations’ treatment of precursors provides a useful 7

example of how the Agency has used Subpart 1 to establish a less

stringent implementation regime than envisioned by Subpart 4. 

Ammonia is a precursor to fine particulate matter, making it a

precursor to both PM and PM . For a PM nonattainment area 2.5 10 10

governed by Subpart 4, a precursor is presumptively regulated. See 42

U.S.C. § 7513a(e). But under the PM rules challenged here, the 2.5

EPA established a rebuttable presumption against regulating ammonia

unless a State or the EPA “provides an appropriate technical

demonstration” that shows emissions from ammonia “significantly

VI-39 A-89
15

meaning of the statutory language and the force of Whitman,

8

EPA offers several unconvincing arguments to support

2.5 implementing the new PM standard pursuant to Subpart 1

rather than Subpart 4.

First, EPA claims Subpart 4 “contains requirements that

are expressly based upon the form of the PM NAAQS.” Br. 10

of Resp’t 31. This may be true but Subpart 4 also expressly

governs implementation of the “PM-10” standard, see 42

U.S.C. §§ 7513-7513b, and the Act defines “PM-10” as

“particulate matter with an aerodynamic diameter less than or

contribute to PM concentration in the nonattainment area.” 40 2.5

C.F.R. § 51.1002(c)(4)(i). When Congress enacted Subpart 4, it

sought to end this administrative gamesmanship.

EPA offers several grounds to distinguish Whitman—none of 8

them persuasive. First EPA notes that the text of Subpart 2 refers

generically to “ozone” while Subpart 4’s text refers specifically to

PM , EPA Br. 36—but Subpart 4’s title refers generically to 10

“Particulate Matter” and, as we have noted, when the 1990

amendments to the CAA were enacted, PM included PM under 10 2.5

both the new statutory definition and the existing EPA definition. 

Second, EPA argues that Subpart 4’s provisions do not

“comprehensively prescribe[] classifications and attainment dates for

all particulate matter nonattainment areas.” Br. of Resp’t 37

(emphasis in original). Subpart 4 may not be as comprehensive as

Subpart 2 but its requirements are specific, more stringent and far less

discretionary than Subpart 1. See supra note 6. Third, EPA contends

2.5 that in contrast to Whitman, EPA’s application of Subpart 1 to PM

does not render Subpart 4 “utterly nugatory” because Subpart 4 still

applies to the remaining PM standard. Br. of Resp’t 37 (quoting 10

Whitman, 531 U.S. at 484). But if EPA’s interpretation stands,

Subpart 4 will be “utterly nugatory” with respect to implementation of

2.5 the PM standard—notwithstanding the Congress expressly directed

10 25 the standard applicable to all PM particles, including PM , be

regulated under Subpart 4.

VI-40 A-90
16

equal to a nominal ten micrometers,” 42 U.S.C. § 7602(t). 

Thus, under Chevron step 1, EPA must implement all

10 2.5 standards applicable to PM —including its PM

standards—pursuant to Subpart 4.

Second, EPA urges that because in the 1987 PM NAAQS

Revisions, it “had considered whether to establish a separate

NAAQS for fine particles, using PM as the indicator,” the 2.5

Congress should have foreseen that it might do so later. Br.

of Resp’t 32. It is not at all clear that the Congress should

have so foreseen—EPA cites a single, vague footnote to

support its claim the Congress was on notice such a change

was likely. Id. at 32 (citing 52 Fed. Reg. at 24,639 n.2

(“Particles in ambient air usually occur in two somewhat

overlapping size distributions, fine (diameter less than 2.5

[micrometers]) and coarse (diameter larger than 2.5

[micrometers]. The two size fractions tend to have different

origins and composition.” (staff document citation omitted)). 

But even were such notice clear, it does not follow that the

Congress therefore intended that a separate PM standard (if 2.5

promulgated) be exempt from Subpart 4’s requirements. As

in Whitman, the possibility of such a change suggests only

that gaps resulting therefrom might “prevent us from

concluding that Congress clearly intended [the specific

pollutant subpart] to be the exclusive, permanent means of

enforcing a revised ozone standard in nonattainment areas.” 

Whitman, 531 U.S. at 484 (emphasis added). It does not

render “utterly nugatory” the restrictions that the 1990

amendments imposed on EPA’s discretion in implementing

the particulate matter standards for all particles 10

micrometers or less in diameter. See id. As the Supreme

Court observed regarding Subpart 2, “[a] plan reaching so far

into the future was not enacted to be abandoned the next time

the EPA reviewed the [pollutant’s] standard—which

Congress knew could happen at any time.” Id. at 485.

VI-41 A-91
17

EPA also argues that the Congress “could have easily

used the general term ‘particulate matter,’ rather than the

specific term ‘PM-10.’ ” Br. of Resp’t 33. That the Congress

could have done so does not negate the reality that the “PM ” 10

standard to which the Congress referred in fact included fine

PM (both under the 1987 Rule and the 1990 statutory 2.5

definition). 

In a final Chevron step 1 effort, EPA asserts that the

legislative history makes the Congress’s intent clear. 

Assuming legislative history could override the plain,

unambiguous directive of Subpart 4, the history cited here is

unconvincing. EPA relies on a single congressman’s

statement: “ ‘The Title I PM-10 provisions of H.R. 3030

somewhat reschedule the attainment dates that would

otherwise apply under the PM-10 standards as promulgated

by EPA.’ ” Br. of Resp’t 39 (quoting A Legislative History of

the Clean Air Act Amendments of 1990, at 2996 (Comm. Print

1993) (statement of Rep. John Murtha)). This statement

avails EPA nought. “[P]utting to one side the fact that this

was the statement of a single [member of Congress], . . . it is

not necessarily inconsistent with” the petitioners’ view that

Subpart 4 continues to apply to PM standards. 2.5 See Grand

Canyon Air Tour Coal. v. FAA, 154 F.3d 455, 474 (D.C. Cir.

1998). At the time the statement was uttered, “the PM-10

standards as promulgated by EPA” applied to all particulate

matter having a diameter equal to or less than 10

micrometers—including what is now denominated PM . 2.5

9

Moreover, “judges must exercise extreme caution before 9

concluding that a statement made in floor debate, or at a hearing, or

printed in a committee document may be taken as statutory gospel, in

light of the endemic interplay, in Congress, of political and legislative

considerations likely unrelated to the interpretive tasks of a court.” 

Tex. Mun. Power Agency v. EPA, 89 F.3d 858, 875 (D.C. Cir. 1996)

(per curiam) (quotation marks and alterations omitted). Here, it is

VI-42 A-92
18

See 1987 PM NAAQS Revisions, 52 Fed. Reg. at 24,639.

 EPA additionally argues that its “reading of the act is, at

minimum, a ‘permissible’ interpretation entitled to deference

under Chevron step two.” Br. of Resp’t 41 (upper case

lowered). This argument is foreclosed, however, under

Chevron step 1 because the statute is plain on its face. 

For the foregoing reasons, we grant the petitions for

review of the Final Clean Air Fine Particle Implementation

Rule, 72 Fed. Reg. 20,586 (Apr. 25, 2007), and the

Implementation of the New Source Review (NSR) Program

2.5 for Particulate Matter Less Than 2.5 Micrometers (PM ), 73

Fed. Reg. 28,321 (May 16, 2008). We remand to EPA to repromulgate these rules pursuant to Subpart 4 consistent with

this opinion.10

So ordered.

hard to ignore “the irony that [EPA] points to the same floor

statement that the [petitioners] contend[] supports [their] opposite

view.” Grand Canyon Air Tour Coal., 154 F.3d at 474 (emphasis in

original).

In light of our disposition, we need not address the petitioners’ 10

challenge to the presumptions in 40 C.F.R. § 51.1002(c)(3)-(4) that

volatile organic compounds and ammonia are not PM precursors as 2.5

Subpart 4 expressly governs precursor presumptions. See 42 U.S.C.

§ 7513a(e). Moreover, we decline the petitioners’ invitation to set a

deadline for EPA upon remand or to retain jurisdiction pending such

action. See Natural Res. Def. Council v. EPA, 489 F.3d 1364, 1375

(D.C. Cir. 2007) (“We decline to set a two year limit on EPA’s

proceedings on remand as the NRDC requests; mandamus affords a

remedy for undue delay.”); North Carolina v. EPA, 550 F.3d 1176,

1178 (D.C. Cir. 2008) (per curiam) (declining invitation to “impose a

definitive deadline by which EPA must correct [clean air rule’s]

flaws” and reminding petitioners of availability of mandamus).

VI-43 A-93
United States Court of Appeals 

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued September 24, 2012 Decided January 22, 2013 

No. 10-1413 

SIERRA CLUB, 

PETITIONER

v. 

ENVIRONMENTAL PROTECTION AGENCY AND LISA PEREZ 

JACKSON, ADMINISTRATOR, 

RESPONDENTS

UTILITY AIR REGULATORY GROUP, 

INTERVENOR

On Petition for Review of Final Actions of 

the United States Environmental Protection Agency 

 David S. Baron argued the cause for petitioner. With him 

on the briefs were Seth L. Johnson and Emma C. Cheuse. 

Jessica O'Donnell, Attorney, U.S. Department of Justice, 

argued the cause for respondents. With her on the brief were 

Brian L. Doster, Assistant General Counsel, U.S. 

Environmental Protection Agency, and Scott J. Jordan, 

Attorney. 

VI-44 A-94
2 

Andrea Bear Field, Makram B. Jaber, Lucinda Minton 

Langworthy, and Elizabeth L. Horner were on the brief for 

intervenor Utility Air Regulatory Group in support of 

respondent. 

Before: SENTELLE, Chief Judge, GRIFFITH, Circuit Judge, 

and EDWARDS, Senior Circuit Judge. 

 Opinion for the Court filed by Chief Judge SENTELLE. 

SENTELLE, Chief Judge: In October 2010, the 

Environmental Protection Agency (“EPA”) issued a final rule 

establishing regulations for particulate matter less than 2.5 

micrometers (“PM2.5”) under § 166 of the Clean Air Act (“the 

Act”), 42 U.S.C. § 7476. See 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), 75 

Fed. Reg. 64,864 (Oct. 20, 2010). In this rule, the EPA 

established Significant Impact Levels (“SILs”) and a 

Significant Monitoring Concentration (“SMC”) for PM2.5, 

screening tools the EPA uses to determine whether a new 

source may be exempted from certain requirements under § 

165 of the Act, 42 U.S.C. § 7475. 75 Fed. Reg. at 64,890–

91, 64,895. Petitioner Sierra Club seeks review of this 

regulation. 

After the Sierra Club filed its petition, the EPA 

acknowledged that portions of the rule establishing SILs did 

not reflect its intent in promulgating the SILs, and now 

requests that we vacate and remand some (but not all) parts of 

its PM2.5 SIL regulations. Notwithstanding the EPA’s 

concession, the Sierra Club maintains that the EPA lacks 

authority to establish SILs and requests that we rule 

VI-45 A-95
3 

accordingly. The Intervenor, Utility Air Regulatory Group 

(“UARG”), on the other hand, urges us to uphold the SIL 

provisions EPA established, or alternatively, to remand the 

SIL provisions without ordering that they be vacated. 

Although the EPA conceded that it needs to revise some 

of the SIL provisions, it continues to assert that the portions of 

its rule establishing the SMC were valid. For the reasons 

stated below, we accept the EPA’s concession on the SILs, 

and vacate and remand some portions of the EPA’s rule 

establishing SILs. We further conclude that the EPA

exceeded its authority in establishing the SMC, and grant the 

Sierra Club’s petition as to those portions of the EPA’s rule. 

I. BACKGROUND

A. The Clean Air Act

The Clean Air Act requires the EPA to set National 

Ambient Air Quality Standards (“NAAQS”) for various 

harmful air pollutants at levels necessary to protect the public 

health and welfare. 42 U.S.C. §§ 7401, 7409. Under the Act,

the EPA must designate areas as attainment, nonattainment, or 

unclassifiable for each NAAQS. Id. § 7407(d)(1)(A). States 

have primary responsibility for implementing the NAAQS, 

and must submit a state implementation plan (“SIP”) 

specifying how the State will achieve and maintain 

compliance with the NAAQS. Id. § 7407(a). 

In 1977, Congress amended the Act to add the Prevention 

of Significant Deterioration (“PSD”) provisions “to protect 

the air quality in national parks and similar areas of special 

scenic or recreational value, and in areas where pollution was 

within the national ambient standards, while assuring 

economic growth consistent with such protection.” 

VI-46 A-96
4 

Environmental Defense Fund v. EPA, 898 F.2d 183, 184 

(D.C. Cir. 1990) (citing 42 U.S.C. § 7470). When Congress 

enacted the PSD provisions, it established maximum 

allowable increases over baseline concentrations — also 

known as “increments” — for certain pollutants in § 163 of 

the Act. See 42 U.S.C. § 7473; Environmental Defense Fund, 

898 F.2d at 184. For other pollutants, Congress delegated to 

the EPA the task of promulgating regulations to prevent the 

significant deterioration of air quality that would result from 

the emissions of these pollutants. 42 U.S.C. § 7476(a). For

pollutants that the EPA began regulating after Congress 

enacted the PSD provisions, which includes PM2.5, the EPA 

must promulgate PSD regulations within two years of 

establishing the NAAQS for that pollutant. Id. 

The PSD provisions also establish requirements for 

preconstruction review and permitting of new or modified 

sources of air pollution. See id. § 7475. Subsection 165(a) of 

the Act lists the requirements an owner or operator proposing 

to construct a new source or modify an existing source must 

meet before starting construction, which include acquiring a 

PSD permit for the facility. Id. § 7475(a)(1)–(2). Of 

relevance to this petition, § 165(a)(3) requires that an owner 

or operator proposing to construct a new major emitting 

facility or modify an existing facility demonstrate that 

emissions from construction or operation of the facility will 

not cause or contribute to any violations of the increment 

more than once per year, or to any violation of the NAAQS 

ever. Id. § 7475(a)(3). 

 

Before a review of the § 165(a) requirements may be

undertaken, however, either a State or the owner or operator

of a facility applying for a PSD permit must conduct an 

analysis of the ambient air quality at the proposed site and in 

areas that may be affected by emissions from the facility for 

VI-47 A-97
5 

the relevant pollutants. Id. § 7475(e)(1). This analysis must 

include continuous air quality monitoring data gathered to 

determine whether the facility will exceed either the 

increments or the NAAQS. Id. § 7475(e)(2). The Act further 

mandates that this data be collected for a year before the date 

the applicant applies for a permit unless a State, in accordance 

with EPA regulations, “determines that a complete and 

adequate analysis for such purposes may be accomplished in a 

shorter time period.” Id. The results of the analysis must be 

made available to the public at the time of the public hearing 

on the application for a PSD permit. Id. 

The Act requires States to address the PSD provisions in 

their SIPs. Id. § 7410(a)(2). The EPA has promulgated 

extensive regulations setting forth requirements and 

guidelines on how SIPs are to implement the PSD provisions. 

See 40 C.F.R. § 51.166. For States without an EPA-approved 

SIP, the EPA has promulgated separate regulations 

implementing the PSD provisions. See 40 C.F.R. § 52.21. 

B. Regulatory Background: Establishing the PM2.5

Increment, SILs, and SMC 

In 1997, the EPA revised its NAAQS to include 

standards for PM2.5, see 62 Fed. Reg. 38,652 (July 18, 1997), 

and in 2006 revised the PM2.5 NAAQS, see 71 Fed. Reg. 

61,144 (Oct. 17, 2006). In 2007, the EPA proposed a rule 

establishing increments for PM2.5. See 72 Fed. Reg. 54,112 

(Sept. 21, 2007). In this rulemaking, the EPA also proposed 

two screening tools that would exempt a permit applicant 

from some of the air quality analysis and monitoring required 

under the Act and EPA regulations: significant impact levels

(“SILs”) and significant monitoring concentration (“SMC”). 

See id. at 54,138–42. 

VI-48 A-98
6 

1. Significant Impact Levels

Under EPA regulations, the owner or operator of a 

proposed source or modification must undertake a source 

impact analysis to demonstrate “that allowable emission 

increases from the proposed source or modification, in 

conjunction with all other applicable emission increases or 

reductions (including secondary emissions), would not cause 

or contribute to” a violation of the increments or the NAAQS. 

40 C.F.R. § 51.166(k); id. § 52.21(k). In the proposed rule, 

the EPA discussed adopting SILs for PM2.5, which the EPA 

defines as “numeric values derived by EPA that may be used 

to evaluate the impact a proposed major source or 

modification may have on the NAAQS or PSD increment.” 

72 Fed. Reg. at 54,138. This numerical value, measured in

micrograms per meter cubed (μg/m3), is the level of ambient 

impact below which the EPA considers a source to have an 

insignificant effect on ambient air quality. 72 Fed. Reg. at 

54,139. According to the EPA’s proposed rule, “a source that 

demonstrates its impact does not exceed a SIL at the relevant 

location is not required to conduct more extensive air quality 

analysis or modeling to demonstrate that its emissions, in 

combination with the emissions of other sources in the 

vicinity, will not cause or contribute to a violation of the 

NAAQS at that location,” an analysis the EPA terms the 

cumulative impact analysis, or the cumulative air quality 

analysis. 72 Fed. Reg. at 54,139. 

As the legal basis for adopting the SILs, the EPA cited 

Alabama Power Co. v. Costle, 636 F.2d 323 (D.C. Cir. 1979). 

72 Fed. Reg. at 54,139. In that case we discussed an 

administrative agency’s de minimis authority to establish 

exemptions from statutory commands, holding that 

“[c]ategorical exemptions may . . . be permissible as an 

VI-49 A-99
7 

exercise of agency power, inherent in most statutory schemes, 

to overlook circumstances that in context may fairly be 

considered de minimis.” 636 F.2d at 360. We further stated 

that “[u]nless Congress has been extraordinarily rigid, there is 

likely a basis for an implication of de minimis authority to 

provide exemption when the burdens of regulation yield a 

gain of trivial or no value.” Id. at 360–61. But that implied 

authority does not apply to situations “where the regulatory 

function does provide benefits, in the sense of furthering the 

regulatory objectives, but the agency concludes that the 

acknowledged benefits are exceeded by the costs.” Id. at 361. 

Applying this de minimis authority, the EPA explains that 

when a source’s ambient impact does not exceed the SIL — 

i.e., is de minimis — the “EPA considers the conduct of a 

cumulative air quality analysis and modeling by such a source 

to yield information of trivial or no value with respect to the 

impact of the proposed source or modification.” 72 Fed. Reg. 

at 54,139. 

2. Significant Monitoring Concentration

In 1980, the EPA “adopted regulations that exempt 

sources from preconstruction monitoring requirements [i.e., 

§ 165(e)(2) of the Act] for a pollutant if the source can 

demonstrate that its ambient air impact is less than a value 

known as the [SMC].” Id. at 54,141. When the EPA first 

adopted SMCs for other pollutants in 1980,1 it described the 

SMCs as “air quality concentration de minimis levels for each 

 

1 When the EPA established the preconstruction monitoring 

exemption in 1980, it did not label the emissions values below 

which the exemption applied as “SMCs,” instead terming them “de 

minimis emissions levels.” See 45 Fed. Reg. 52,676, 52,709 (Aug. 

7, 1980). But because the de minimis emissions levels promulgated 

in 1980 serve the same function as the PM2.5 SMC, we will refer to 

the 1980 de minimis levels as SMCs throughout this opinion. 

VI-50 A-100
8 

pollutant for the purpose of providing a possible exemption 

from monitoring requirements.” Id. (internal alterations and 

citations omitted). In its proposed rule establishing an SMC 

for PM2.5, the EPA explained that “[i]f a source can show 

through modeling of its emissions alone that its impacts are 

less than the corresponding SMC, there is little to be gained 

by requiring that source to collect additional monitoring data 

on PM2.5 emissions to establish background concentrations for 

further analysis.” Id. The EPA proposed different 

methodologies for establishing a value for the SMC and, as 

with the SILs, relied on the de minimis discussion from 

Alabama Power as the legal basis for establishing an SMC for 

PM2.5. 72 Fed. Reg. at 54,141. 

C. Final Rule

In its final rule, the EPA adopted and set values for both 

the SILs and SMC for PM2.5. See 75 Fed. Reg. at 64,864. 

The EPA gave three purposes for the SILs in the final rule, 

which were to determine:

 

(1) When a proposed source’s ambient impacts 

warrant a comprehensive (cumulative) source impact 

analysis; (2) the size of the impact area within which 

the air quality analysis is completed, and (3) whether 

the emissions increase from a proposed new major 

stationary source or major modification is considered 

to cause or contribute to a violation of any NAAQS. 

Id. at 64,890. 

In adopting the SMC, the EPA emphasized that it 

retained discretion “to determine when it may be appropriate 

to exempt a proposed new major stationary source or major 

modification from the ambient monitoring data requirements 

VI-51 A-101
9 

under the PSD rules.” Id. at 64,895. The rule codified the 

SILs at 40 C.F.R. § 51.166(k)(2) and 40 C.F.R. § 52.21(k)(2), 

and the SMC at 40 C.F.R. § 51.166(i)(5)(i)(c) and 40 C.F.R. 

§ 52.21(i)(5)(i)(c). 75 Fed. Reg. at 64,902–07. 

The rule also codified the PM2.5 SILs in the EPA’s 

regulations on new source review and permitting 

requirements at 40 C.F.R. § 51.165(b)(2). Unlike the PSD 

regulations (40 C.F.R. §§ 51.166, 52.21), § 51.165(b)(2) does 

not use the SILs to exempt a source from conducting a 

cumulative air quality analysis. Instead, § 51.165(b)(2) states 

that a proposed source or modification will be considered to 

cause a violation of a NAAQS when that source or 

modification would, at a minimum, exceed the SIL in any 

area that does not or would not meet the applicable NAAQS. 

II. ANALYSIS

A. Significant Impact Levels 

The Sierra Club argues that the EPA lacks de minimis

authority to promulgate the SILs. Specifically, the Sierra 

Club contends that the language of § 165 is so extraordinarily 

rigid that it bars de minimis exemptions, and that adoption of 

the SILs is contrary to the legislative design of the Act. Even 

if § 165 of the Act were not so extraordinarily rigid as to bar 

any de minimis exemption, the Sierra Club asserts that 

pollution increases below the SILs are not so trivial as to be

de minimis. 

To illustrate the latter point, the Sierra Club explains that 

if a proposed source or modification is in an area that is close 

to violating the NAAQS or an increment, that source could 

violate the NAAQS or increment even if its emissions would 

have an ambient impact below the SIL. For example, if a 

VI-52 A-102
10 

proposed source’s emission of PM2.5 would have a projected

air quality impact of 1 μg/m3 over a 24-hour average (below 

the SIL of 1.2 μg/m3 over a 24-hour average), and that source 

proposes to build in an area that already has an ambient PM2.5

concentration of 35 μg/m3

 (the PM2.5 NAAQS over a 24-hour 

average), the construction of that source could cause a 

violation of the NAAQS. See id. §§ 50.13(c) (PM2.5

NAAQS), 51.166(k)(2) (PM2.5 SIL). The Sierra Club further 

notes that because the EPA’s regulation automatically 

exempts a source with a proposed impact below the SIL from 

demonstrating it will not cause or contribute to a violation of 

the NAAQS, unlimited numbers of sources whose impacts are 

less than the SILs could cumulatively cause a violation of the 

NAAQS or increments. Also, the Sierra Club points out that

sources whose impact is below the SILs that construct in an

upwind attainment area could worsen existing violations in a 

downwind nonattainment area. As the SIL regulations are 

currently written, sources in these scenarios would not be 

required to demonstrate that they would not cause or 

contribute to a violation of the NAAQS or increment, even 

though they likely would cause a violation (in an attainment 

area) or contribute to a violation (in a downwind 

nonattainment area), thus contravening the statutory 

command in § 165(a) of the Act. 

In its brief, the EPA concedes that the SIL provisions, as 

codified, were flawed. When the EPA responded to

commenters in the final rule, it explained that 

“notwithstanding the existence of a SIL, permitting authorities 

should determine when it may be appropriate to conclude that 

even a de minimis impact will ‘cause or contribute’ to an air 

quality problem and to seek remedial action from the 

proposed new source or modification.” 75 Fed. Reg. at 

64,892. But as the EPA acknowledges in its brief, “the 

regulatory text it adopted does not allow permitting 

VI-53 A-103
11 

authorities the discretion to require a cumulative impact 

analysis, notwithstanding that the source’s impact is below 

the SIL, where there is information that shows the proposed 

source would lead to a violation of the NAAQS or 

increments.” Resp’t Br. at 34. Because the EPA asserts that 

it did not intend to automatically exempt a proposed source 

from the requirements of the Act without affording the 

permitting authorities discretion in applying the SILs, it 

requests that we vacate and remand the regulatory text 

promulgated in the rule at 40 C.F.R. §§ 51.166(k)(2) and 

52.21(k)(2). 

Despite the EPA’s concession, the Sierra Club asserts 

that vacatur and remand, while warranted, does not fully 

resolve its challenge, and asks that we determine whether the 

EPA has authority to promulgate SILs. We disagree with the 

Sierra Club that it is necessary to decide the EPA’s authority 

to promulgate SILs at this point. To do so would require that 

we answer a question not prudentially ripe for determination. 

On remand the EPA may promulgate regulations that do not 

include SILs or do include SILs that do not allow the 

construction or modification of a source to evade the 

requirements of the Act as do the SILs in the current rule. In 

such an event, we would not need to address the universal 

disallowance of all de minimis authority. If the EPA 

promulgates new SIL provisions for PM2.5 and those 

provisions are challenged, we can then consider the 

lawfulness of those SIL provisions. 

While the Sierra Club argues that simply vacating and 

remanding the SIL provisions does not go far enough, the 

UARG intervenes to argue that vacatur and remand go too far. 

The UARG asserts that remanding the SIL provisions for 

further rulemaking is unnecessary for two reasons. First,

intervenor asserts, the SIL provisions, as informed by the 

VI-54 A-104
12 

EPA’s statements during rulemaking, do allow permitting 

authorities discretion in how they apply the SILs. Second, it 

argues that if a source with an ambient impact below the SIL 

does cause a NAAQS or increment violation in an area, the 

permitting authority for that area is already obligated to revise 

its SIP to address the violation. See 40 C.F.R. § 51.166(a)(3). 

The UARG bases the first of these arguments on the 

premises that an agency’s interpretation of its own regulations 

is given deference, and that the EPA has interpreted the SIL 

provisions so that permitting authorities retain discretion in 

applying the SILs. See Auer v. Robbins, 519 U.S. 452, 461 

(1997) (explaining that an agency’s interpretation of its own 

regulations is “controlling unless plainly erroneous or 

inconsistent with the regulation.”) (internal citations and 

quotation marks omitted). Although the first premise is true, 

the latter premise is contradicted by the EPA’s statements in 

its brief that the regulatory text it adopted does not give 

permitting authorities sufficient discretion to require a 

cumulative air quality analysis. That the EPA itself requests 

that we remand these provisions strongly argues that the 

current SIL provisions do not give permitting authorities 

sufficient discretion in applying the SILs.

 The text of the SIL regulations as codified in the Code of 

Federal Regulations supports the EPA’s interpretation that the 

SILs do not allow a permitting authority sufficient discretion. 

Cf. Auer, 519 U.S. at 461 (opining that a critical phrase in the 

contested regulation “comfortably bears the meaning the 

[agency] assigns.”). Although 40 C.F.R. § 51.166(k)(2), 

which applies to SIPs, states that a plan “may provide” for the 

use of SILs to exempt a proposed source or modification from 

undertaking a cumulative air quality analysis, it does not give 

permitting authorities that implement the SILs discretion to 

require a cumulative air quality analysis for sources that are 

VI-55 A-105
13 

below the SIL, but could nevertheless cause a violation of the 

NAAQS or increment. And 40 C.F.R. § 52.21(k)(2), which 

applies to states without an approved SIP, goes even further 

and simply states that the demonstration required under 

§ 165(a)(3) is deemed to have been made if a proposed source 

or modification’s air quality impact is below the SIL.

The UARG’s second argument, that remand is 

unnecessary because the EPA requires permitting authorities 

to address violations by revising their SIPs, also does not 

persuade us that we should deny the EPA’s request to remand 

its regulations on the PM2.5 SILs. The PSD provisions 

Congress enacted may not have specified how the owner or 

operator of a proposed source or modification must 

demonstrate compliance, but they do require demonstration 

that the source will not cause or contribute to a violation of 

the NAAQS or increment as a precondition to construction. 

See 42 U.S.C. § 7475(a)(3). As the Sierra Club notes, relying 

on permitting authorities to address violations, rather than to 

prevent violations by requiring demonstration that a proposed 

source or modification will not cause a violation, conflicts 

with this statutory command. 

The UARG finally argues that if we remand the SIL 

regulations, we should not vacate the regulations, based on 

our holding in Fertilizer Institution v. EPA, 935 F.2d 1303 

(D.C. Cir. 1991), where we stated that “when equity demands, 

an unlawfully promulgated regulation can be left in place 

while the agency provides the proper procedural remedy.” Id.

at 1312. According to the UARG, leaving the SIL provisions 

in place during the new rulemaking would cause no harm to 

air quality, while vacating the SIL provisions would have 

“disruptive consequences” for economic growth — i.e., by 

adding additional burdens to sources with de minimis impacts. 

VI-56 A-106
14 

Therefore, the UARG asserts that equity requires we do not 

vacate the SIL provisions. 

The UARG’s equitable argument does not persuade us. 

In Fertilizer Institution we left in place administrative 

exemptions the EPA adopted without providing adequate 

notice and comment, a procedural defect, while in this case 

the EPA has requested we vacate and remand the SILs 

because it did not have authority to promulgate such a broad 

exemption. See id. Because this is a substantive defect, and 

because the EPA explicitly requested we vacate and remand 

some of its SIL provisions, we will grant its request 

notwithstanding the UARG’s opposition. 

Although the EPA asks us to vacate and remand the parts 

of its rule codifying SILs at §§ 51.166(k)(2) and 52.21(k)(2), 

it requests that we let the promulgation of SILs in 

§ 51.165(b)(2) remain operative, emphasizing that the Sierra 

Club’s challenge of the EPA’s authority to promulgate SILs 

was directed only at the first two regulations. We agree that 

the parts of the EPA’s rule codifying SILs in § 51.165(b)(2) 

should remain. We are remanding the other regulations 

because they allow permitting authorities to automatically 

exempt sources with projected impacts below the SILs from 

having to make the demonstration required under 42 U.S.C. § 

7475(a)(3), even in situations where the demonstration may 

require a more comprehensive air quality analysis. These 

concerns, which are based on whether the EPA has authority 

to exempt those requirements, are not present in § 

51.165(b)(2), which simply states that a source may be 

deemed to violate the NAAQS if it exceeds the SILs in certain 

situations. Apparently, for that reason, the Sierra Club only 

addresses § 51.165(b)(2) in the section of its brief challenging 

the EPA’s methodology in setting SILs, and not in the section 

challenging the EPA’s authority to promulgate SILs. See 

VI-57 A-107
15 

Pet’r Br. at 32 n.12, 37 n.17. We are not now ruling on the 

methodology the EPA used to determine the SILs. Instead, 

we are vacating and remanding §§ 51.166(k)(2) and 

52.21(k)(2) based on the EPA’s lack of authority to exempt 

sources from the requirements of the Act. Therefore, vacatur 

and remand of § 51.165(b)(2) is not necessary at this point. 

Accordingly, we vacate and remand the portions of the 

EPA’s rule regarding SILs, with the exception of those 

portions codified in 40 C.F.R. § 51.165(b)(2). 

B. Significant Monitoring Concentrations 

As with the SILs, the Sierra Club argues that the EPA 

does not have de minimis authority to promulgate an SMC for 

PM2.5 that can be used to exempt an owner of a proposed 

source or modification from undertaking the year-long preconstruction air quality monitoring requirement under 

§ 165(e)(2) of the Act. As a threshold issue, however, the 

EPA argues that the Sierra Club’s challenge is time-barred

under § 307(b)(1) of the Act because the EPA has used SMCs 

as a screening tool since 1980. See 42 U.S.C. § 7607(b)(1); 

45 Fed. Reg. 52,676, 52,710 (Aug. 7, 1980) (explaining that a 

source owner may be exempt from preconstruction 

monitoring if the source’s projected impact is de minimis).

We disagree with the EPA that the Sierra Club’s petition is 

time-barred, and we agree with the Sierra Club that the EPA 

did not have de minimis authority to promulgate the SMC 

because we hold Congress was “extraordinarily rigid” in 

mandating preconstruction air quality monitoring. 

Section 307(b)(1) of the Act requires a petitioner seeking 

review of an EPA regulation to file its petition within sixty 

days from the date the challenged regulation was published in 

the Federal Register. 42 U.S.C. § 7607(b)(1). The EPA relies 

VI-58 A-108
16 

on our decision in Medical Waste Institute and Energy 

Recovery Council v. EPA, 645 F.3d 420 (D.C. Cir. 2011), to 

argue that § 307(b)(1) bars the Sierra Club’s challenge to the 

PM2.5 SMC. In that case, the petitioner challenged the EPA’s 

approach to setting the level of emissions control for 

pollutants emitted by medical waste incinerators. Id. at 422. 

The EPA had initially set these levels in 1997, but we 

remanded its regulations after granting an environmental 

organization’s petition for review. Id. at 423. The EPA 

issued a new rule in 2009 setting even more stringent levels 

for emissions control than it had in 1997, prompting another 

petition for review, this time by an industry organization. Id.

at 424. In remaking the rule, the EPA used the same approach 

to setting the levels of emissions control for the same set of 

pollutants as it did in 1997, but used a different data set. Id. 

at 426–27. We held that because no one challenged the 

approach to setting levels of emissions control in 1997 — the 

same approach the EPA used in its 2009 regulation — the 

petitioners had failed to file a timely petition, and their 

challenge was thus barred by § 307(b)(1). Id. at 427. 

Our holding in Medical Waste Institute, however, does 

not apply in this case. The EPA has promulgated new 

regulations for a pollutant it did not regulate in 1980. See 45 

Fed. Reg. at 52,733–34 (listing SMCs for various pollutants 

that does not include PM2.5). By establishing a new 

monitoring exemption for a new pollutant, the EPA exposes 

its PM2.5 regulations, including whether it has authority to 

adopt the SMC exemption for PM2.5 and whether it used an 

appropriate method to determine the level of the SMC, to 

challenge by a timely filed petition. In Ohio v. EPA, 838 F.2d 

1325, 1328 (D.C. Cir. 1988), we opined that “the period for 

seeking judicial review may be made to run anew when the 

agency in question by some new promulgation creates the 

opportunity for renewed comment and objection.” Although 

VI-59 A-109
17 

not a parallel to this case in that the Ohio case concerned a 

reopening, we consider its reasoning instructive. 

This, of course, does not mean that a petitioner’s 

challenge to the EPA’s authority will always survive, as the 

EPA’s authority to promulgate certain regulations could be 

well-settled. The solution, however, is not to bar any

challenges to that authority under § 307(b)(1) of the Act, but 

instead to consider the timely challenge and any relevant

precedent demonstrating that the EPA has the authority in 

dispute. Because we have not yet decided whether the EPA’s 

de minimis authority allows it to establish SMCs as a 

screening tool to determine when to exempt sources from the 

Act’s preconstruction monitoring requirement, we will

consider whether the EPA had authority to adopt an SMC for 

PM2.5. 

Subsection (e) of § 165 of the Act requires that before a 

PSD permit application can be reviewed, either the State or 

the permit applicant must conduct an analysis of the ambient 

air quality at the proposed site and in areas which the 

applicant’s facility may affect. 42 U.S.C. § 7475(e)(1). 

Under subsection (e)(2), this analysis 

shall include continuous air quality monitoring data 

gathered for purposes of determining whether 

emissions from such facility will exceed the 

[increment] or the maximum allowable concentration 

permitted under [the NAAQS]. Such data shall be 

gathered over a period of one calendar year preceding 

the date of application for a permit under this part 

unless the State, in accordance with regulations 

promulgated by the [EPA], determines that a complete 

and adequate analysis for such purposes may be 

accomplished in a shorter period. The results of such 

VI-60 A-110
18 

analysis shall be available at the time of the public 

hearing on the application for such permit. 

Id. § 7475(e)(2).

We read § 165(e)(2) of the Act as an “extraordinarily 

rigid” mandate that a PSD permit applicant undertake 

preconstruction monitoring. Indeed, we recognized the 

rigidity of this subsection in Alabama Power when we held 

that “[t]his is a plain requirement for inclusion of monitoring 

data.” Alabama Power, 636 F.2d at 372 (holding that the 

EPA did not have authority to dispense with monitoring 

where Congress mandated the use of that technique, even 

though monitoring technology at the time was limited). 

Congress’s use of the word “shall” in each sentence of the Act 

evidences a clear legislative mandate that the preconstruction 

monitoring requirement applies to PSD permit applicants.

That Congress provided only one exception to this monitoring 

requirement — a shorter monitoring period — suggests that 

Congress did not intend any other exceptions. See Sierra 

Club v. EPA, 294 F.3d 155, 160 (D.C. Cir. 2002). If Congress 

sought to give the EPA discretion to eliminate the monitoring 

requirement it could have used less rigid language to achieve 

that result, as it has in other subsections of § 165. For 

example, in 42 U.S.C. § 7475(e)(2), Congress provided that

“[air quality] data shall be gathered over a period of one 

calendar year preceding the date of application for a permit 

under this part unless the State, in accordance with regulations 

promulgated by the [EPA], determines that a complete and 

adequate analysis for such purposes may be accomplished in a 

shorter period.” (emphasis added). In contrast, § 7475(a)(7) 

requires as a condition for obtaining a PSD permit, that an 

owner or operator of a proposed source or modification agree 

to post-construction monitoring as “may be necessary to 

determine the effect which emissions” from the facility may 

VI-61 A-111
19 

have on air quality. (emphasis added). Moreover, the 

exception for a shorter monitoring period only applies when 

the permitting authority determines that a complete and 

adequate analysis may be accomplished in a shorter period. 

EPA has not explained how a “complete and adequate” 

analysis may be accomplished without any of the monitoring 

data required by § 165(e)(2). 

Given how extraordinarily rigidly Congress stated its 

monitoring mandate in § 165(e)(2), we are not persuaded by 

the EPA’s arguments that it has de minimis authority to 

exempt the preconstruction monitoring requirement. The 

EPA argues that the Sierra Club fails to show that the statute 

is so rigid that it precludes the exercise of the EPA’s de 

minimis authority. The EPA, however, does not explain how 

the statute is ambiguous, but instead asserts that there is a 

“virtual presumption” of inherent agency authority. Resp’t 

Br. at 46; see Public Citizen v. Young, 831 F.2d 1108, 1113 

(D.C. Cir. 1987). This argument is circular. Even if a 

“virtual presumption” exists, that presumption can be rebutted 

by an “extraordinarily rigid” statutory mandate. See Public 

Citizen, 831 F.2d at 1113. Whether we call preconstruction 

monitoring a “plain requirement” or a requirement mandated 

by an “extraordinarily rigid” statute, the result is the same: the 

EPA has no de minimis authority to exempt the requirement. 

 Without pointing out any ambiguity in Congress’s 

mandate, the EPA asserts that the purpose of the statute’s 

preconstruction monitoring requirement “is to provide data 

for purposes of performing an air quality analysis,” and that it 

can reasonably conclude “the statute permits an exemption for 

collection of data that is not useful to carrying out the 

purposes of the statute.” Resp’t Br. at 49. The EPA confuses 

the purpose of § 165(e)(2)’s monitoring requirement. The 

statute explicitly states that one purpose of the monitoring 

VI-62 A-112
20 

requirement is to determine whether emissions from a 

proposed source or modification will exceed the increments or 

NAAQS. 42 U.S.C. § 7475(e)(2). We logically infer from 

this statement that Congress intended the monitoring 

requirement to establish the baseline air quality in an area 

before the owner of a proposed source or modification even 

applies for a PSD permit. If an area’s pre-existing ambient 

PM2.5 concentration is so high that a violation of the NAAQS 

or increment is imminent, a source below the SMC may 

nevertheless cause a violation if built or modified. This is 

true even if the source’s projected ambient impact on PM2.5 is 

so low that the difference in air quality before and after 

construction would be impossible to measure with accuracy. 

But a permitting authority cannot know how close an area is 

to violating the NAAQS or increment unless it knows the 

existing ambient concentrations of PM2.5 before a source is 

constructed or modified. 

The EPA’s argument also fails to address Congress’s 

mandate that the results of the air quality analysis required by 

§ 165(e) be made available to the public at the time of a 

hearing for a PSD permit. Id. § 7475(e)(2). Indeed, one of 

Congress’s stated purposes in enacting the PSD provisions 

was “to assure that any decision to permit increased air 

pollution in any area to which” the PSD provisions apply be 

made only after careful evaluation by the permitting authority 

and “after adequate procedural opportunities for informed

public participation in the decisionmaking process.” 42 

U.S.C. § 7470(5) (emphasis added). Congress’s express 

statement that the public shall have air quality data to allow 

for informed participation in PSD application hearings 

bolsters our conclusion that the EPA has no authority to 

exempt the monitoring requirement.

VI-63 A-113
21 

In addition to arguing that § 165(e)(2) was 

extraordinarily rigid, the Sierra Club contends that the EPA

has no de minimis authority because the PM2.5 SMC thwarts 

the legislative design of the Act. The EPA addresses this

argument by making two arguments. First, the EPA states 

that it has advised permitting authorities not to apply the 

monitoring exemption when an area’s ambient concentration 

is close to the NAAQS or the consumption of the increment. 

Second, the EPA asserts that exempting preconstruction 

monitoring in areas where the ambient concentration itself is 

below the SMC (and thus not capable of accurate 

measurement, regardless of a proposed source’s projected 

impact) furthers legislative design by avoiding pointless 

expenditures of effort. 

Both these points ignore the rigidity of the statute. 

Because the statute leaves no room for exemptions, such as 

those at issue, granting the permitting authorities discretion to 

apply the exemption is beyond the EPA’s statutory authority. 

As to the EPA’s second point, we agree with the Sierra Club 

that the estimation that an area is below the SMC does not 

render monitoring superfluous because monitoring could 

reveal that the estimate was incorrect. More importantly, 

Congress provided a clear mandate that the EPA does not 

have authority to disregard, even if the mandated 

requirements appear to it to be superfluous. 

To authorize the EPA to exempt the plain requirement of 

preconstruction monitoring and to retain (and delegate) 

discretion on when such an exemption should apply would 

allow the EPA to engage in an impermissible cost-benefit 

analysis. As we explained in Alabama Power, “implied 

authority is not available for a situation where the 

regulatory function does provide benefits, in the sense of 

furthering the regulatory objectives, but the agency concludes 

VI-64 A-114
22 

that the acknowledged benefits are exceeded by the costs.” 

Alabama Power, 636 F.2d at 361. To engage in cost-benefit 

decisions, the EPA’s implied authority “must be based not on 

a general doctrine but on a fair reading of the specific statute, 

its aims and legislative history.” Id. The monitoring 

requirement is a regulatory function that provides benefits, 

and the statute precludes the EPA from exempting that 

requirement. Although the year-long preconstruction 

monitoring requirement may be onerous and, in some cases, 

EPA deems it more costly than beneficial, the EPA may not

substitute its policy for that of Congress. 

III. CONCLUSION

For the foregoing reasons, we vacate and remand to the 

agency for further consideration the portions of the EPA’s 

rule addressing SILs, except for the parts of its rule codifying 

PM2.5 SILs in 40 C.F.R. § 51.165(b)(2). We grant the Sierra 

Club’s petition as to the parts of the EPA’s rule establishing a 

PM2.5 SMC, and vacate them because these parts of the rule

exceed the EPA’s statutory authority. See 42 U.S.C. 

§ 7607(d)(9)(3). 

So ordered. 

VI-65 A-115
Federal Register / Vol. 73, No. 96 / Friday, May 16, 2008 / Rules and Regulations 28321 

No comments objecting to the proposal 

were received. Class E airspace areas 

extending from 700 feet or more above 

the surface of the earth are published in 

paragraphs 6005 of FAA Order 7400.96, 

signed August 14, 2007, and effective 

September 15, 2007, which is 

incorporated by reference in 14 CFR 

71.1. The class airspace designation 

listed in this document will be 

published subsequently in the Order. 

The Rule 

The FAA is amending Title 14, Code 

of Federal Regulations (14 CFR) part 71 

to modify Class E airspace at 

Waynesburg, PA, by providing 

additional controlled airspace for 

aircraft executing the RNAV (GPS) 

Runway 09/27 to the Green County 

Airport. This action also corrects the 

geographic position coordinates of the 

airport. 

The FAA has determined that this 

regulation only involves an established 

body of technical regulations for which 

frequent and routine amendments are 

necessary to keep them operationally 

current. It, therefore, (1) is not a 

‘‘significant regulatory action’’ under 

Executive Order 12866; (2) is not a 

‘‘significant rule’’ under DOT 

Regulatory Policies and Procedures (44 

FR 11034; February 26, 1979); and (3) 

does not warrant preparation of a 

Regulatory Evaluation as the anticipated 

impact is so minimal. Since this is a 

routine matter that will only affect air 

traffic procedures and air navigation, it 

is certified that this rule, when 

promulgated, will not have a significant 

economic impact on a substantial 

number of small entities under the 

criteria of the Regulatory Flexibility Act. 

The FAA’s authority to issue rules 

regarding aviation safety is found in the 

Title 49 of the United States Code. 

Subtitle I, Section 106 describes the 

authority of the FAA administrator. 

Subtitle VII, Aviation Programs, 

describes in more detail the scope of the 

agency’s authority. 

This rulemaking is promulgated 

under the authority described in 

Subtitle VII, Part A, Subpart I, Section 

40103. Under that section, the FAA is 

charged with prescribing regulations to 

assign the use of airspace necessary to 

ensure the safety of aircraft and the 

efficient use of airspace. This regulation 

is within the scope of that authority as 

it modifies Class E Airspace at 

Waynesburg, PA. 

List of Subjects in 14 CFR Part 71 

Airspace, Incorporation by reference, 

Navigation (air). 

Adoption of the Amendment 

■ In consideration of the foregoing, the 

Federal Aviation Administration 

amends 14 CFR part 71 as follows: 

PART 71—DESIGNATION OF CLASS A, 

CLASS B, CLASS C, CLASS D, AND 

CLASS E AIRSPACE AREAS; 

AIRWAYS; ROUTES; AND REPORTING 

POINTS 

■ 1. The authority citation for part 71 

continues to read as follows: 

Authority: 49 U.S.C. 106(g); 40103, 40113, 

40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959– 

1963 Comp., p. 389. 

§ 71.1 [Amended] 

■ 2. The incorporation by reference in 

14 CFR 71.1 of Federal Aviation 

Administration Order 7400.9R, Airspace 

Designations and Reporting Points, 

signed August 15, 2007, and effective 

September 15, 2007, is amended as 

follows: 

Paragraph 6005 Class E Airspace Areas 

Extending Upward from 700 feet or More 

Above the Surface of the Earth. 

* * * * * 

AEA PA E5 Waynesburg, PA [Revised] 

Green County Airport, PA 

(Lat. 39°54′04′′ N., long. 80°07′51′′ W.) 

That airspace extending upward from 700 

feet above the surface of the Earth within an 

8.3-mile radius of Green County Airport. 

* * * * * 

Issued in College Park, Georgia, on April 

21, 2008. 

Lynda G. Otting, 

Acting Manager, System Support Group, 

Eastern Service Center, Air Traffic 

Organization. 

[FR Doc. E8–10425 Filed 5–15–08; 8:45 am] 

BILLING CODE 4910–13–M 

DEPARTMENT OF HOMELAND 

SECURITY 

Coast Guard 

33 CFR Part 165 

[Docket No. USCG–2008–0366] 

Security Zone; Portland Rose Festival 

on Willamette River 

AGENCY: Coast Guard, DHS. 

ACTION: Notice of enforcement of 

regulation. 

SUMMARY: The Coast Guard will enforce 

the Portland Rose Festival Security 

Zone on the Willamette River from 1 

a.m. on June 4, 2008 until 10 a.m. June 

10, 2008. This action is necessary for the 

security of public vessels on a portion 

of the Willamette River during the fleet 

week of the Rose Festival. This security 

zone provides for the regulation of 

vessel traffic in the vicinity of the 

moored public vessels. During the 

enforcement period, entry into this zone 

is prohibited unless authorized by the 

Captain of the Port or his designee. 

DATES: The regulations in 33 CFR 

165.1312 will be enforced commencing 

from 1 a.m. on June 4, 2008 until 10 

a.m. June 10, 2008. 

FOR FURTHER INFORMATION CONTACT: 

MST1 Lucia Mack, Coast Guard Sector 

Portland, 6767 N. Basin Ave, Portland, 

OR 97217, telephone 503–240–9311. 

SUPPLEMENTARY INFORMATION: The Coast 

Guard will enforce the Rose Festival 

Security Zone established by 33 CFR 

165.1312 from 1 a.m. on June 4, 2008 

until 10 a.m. June 10, 2008. 

Under the provisions of 33 CFR 

165.33 a vessel may not enter the 

regulated area, unless it receives 

permission from the Captain of the Port 

or his designee. The Coast Guard may be 

assisted by other Federal, State, or local 

law enforcement agencies in enforcing 

this regulation. 

This notice is issued under authority 

of 33 CFR 165.1312 and 5 U.S.C. 552(a). 

In addition to this notice in the Federal 

Register, the Coast Guard will provide 

the maritime community with extensive 

advance notification of this enforcement 

period via the Local Notice to Mariners 

and marine information broadcasts. 

Dated: May 6, 2008. 

F.G. Myer, 

Captain, U.S. Coast Guard, Captain of the 

Port, Portland. 

[FR Doc. E8–10921 Filed 5–15–08; 8:45 am] 

BILLING CODE 4910–15–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Parts 51 and 52 

[EPA–HQ–OAR–2003–0062; FRL–8566–1] 

RIN 2060–AN86 

Implementation of the New Source 

Review (NSR) Program for Particulate 

Matter Less Than 2.5 Micrometers 

(PM2.5) 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The EPA is finalizing 

regulations to implement the New 

Source Review (NSR) program for fine 

particulate matter (that is, particles with 

an aerodynamic diameter less than or 

equal to a nominal 2.5 micrometers, 


sroberts on PROD1PC70 with RULES

VI-66 A-116
28322 Federal Register / Vol. 73, No. 96 / Friday, May 16, 2008 / Rules and Regulations 

generally referred to as ‘‘PM2.5’’). The 

NSR program was created by the Clean 

Air Act (Act or CAA) to ensure that 

stationary sources of air pollution are 

constructed or modified in a manner 

that is consistent with air quality goals 

in the area. 

The Clean Air Fine Particle 

Implementation Rule, which was 

proposed in the Federal Register on 

November 1, 2005, included 

requirements and guidance for State and 

local air pollution agencies to follow in 

developing State implementation plans 

(SIPs) and also the NSR provisions. The 

final implementation rule that was 

promulgated on April 25, 2007, 

included all the SIPs related provisions. 

In this rulemaking, EPA is finalizing the 

NSR provisions of the November 1, 2005 

proposed rule including the major 

source threshold, significant emissions 

rate, and offset ratios for PM2.5, 

interpollutant trading for offsets and 

applicability of NSR to PM2.5 precursors. 

DATES: This final rule is effective on July 

15, 2008. 

ADDRESSES: The EPA has established a 

docket for this action under Docket ID 

No. EPA–HQ–OAR–2003–0062. All 

documents in the docket are listed on 

the www.regulations.gov Web site. 

Although listed in the index, some 

information may not be publicly 

available, e.g., CBI or other information 

whose disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the Internet and will be publicly 

available only in hard copy form. 

Publicly available docket materials are 

available either electronically through 

www.regulations.gov or in hard copy at 

the Air Docket, EPA/DC, EPA West, 

Room 3334, 1301 Constitution Avenue, 

Northwest, Washington, DC. The Public 

Reading Room is open from 8:30 a.m. to 

4:30 p.m., Monday through Friday, 

excluding legal holidays. The telephone 

number for the Public Reading Room is 

(202) 566–1744, and the telephone 

number for the Air Docket is (202) 566– 

1742. 

FOR FURTHER INFORMATION CONTACT: Mr. 

Raghavendra (Raj) Rao, Air Quality 

Policy Division, Office of Air Quality 

Planning and Standards (C504–03), U.S. 

Environmental Protection Agency, 

Research Triangle Park, North Carolina 

27711, telephone number: (919) 541– 

5344, facsimile number: (919) 541–5509, 

e-mail address: rao.raj@epa.gov; or Mr. 

Dan deRoeck, at the same address, 

telephone 919–541–5593, or e-mail at 

deroeck.dan@epa.gov. 

SUPPLEMENTARY INFORMATION: 

I. General Information 

A. Does this action apply to me? 

Entities affected by this rule include 

sources in all industry groups. The 

majority of sources potentially affected 

are expected to be in the following 

groups: 

Industry group NAICSa

Electric services ........................................................................................ 221111, 221112, 221113, 221119, 221121, 221122 

Petroleum refining .................................................................................... 32411 

Industrial inorganic chemicals .................................................................. 325181, 32512, 325131, 325182, 211112, 325998, 331311, 325188 

Industrial organic chemicals ..................................................................... 32511, 325132, 325192, 325188, 325193, 32512, 325199 

Miscellaneous chemical products ............................................................. 32552, 32592, 32591, 325182, 32551 

Natural gas liquids .................................................................................... 211112 

Natural gas transport ................................................................................ 48621, 22121 

Pulp and paper mills ................................................................................. 32211, 322121, 322122, 32213 

Paper mills ................................................................................................ 322121, 322122 

Automobile manufacturing ........................................................................ 336111, 336112, 336712, 336211, 336992, 336322, 336312, 33633, 

33634, 33635, 336399, 336212, 336213 

Pharmaceuticals ....................................................................................... 325411, 325412, 325413, 325414 

a North American Industry Classification System. 

Entities affected by this rule also 

include States, local reviewing 

authorities, and Indian country with 

new and modified major stationary 

sources. 

B. Where can I get a copy of this 

document and other related 

information? 

In addition to being available in the 

docket, an electronic copy of this final 

rule will also be available on the World 

Wide Web. Following signature by the 

EPA Administrator, a copy of this final 

rule will be posted in the regulations 

and standards section of our NSR home 

page located at http://www.epa.gov/nsr. 

C. How is this preamble organized? 

The information presented in this 

preamble is organized as follows: 

I. General Information 

A. Does this action apply to me? 

B. Where can I get a copy of this document 

and other related information? 

C. How is this preamble organized? 

II. Purpose 

III. Background 

A. New Source Review (NSR) Program 

B. Fine Particulate Matter and the NAAQS 

for PM2.5

C. Implementation of NSR for PM2.5

IV. Overview of This Final Action 

V. Rationale for Final Actions 

A. Applicability of NSR to Precursors of 

PM2.5 in the Ambient Air 

1. What is EPA’s legal authority to regulate 

precursors? 

2. What is EPA’s approach for addressing 

precursors? 

3. Final Action on SO2

4. Final Action on NOX

5. Final Action on VOC 

6. Final Action on Ammonia 

B. Major Stationary Source Threshold for 

PM2.5

C. Significant Emissions Rate for Direct 

Emissions of PM2.5

D. Significant Emissions Rates for PM2.5

Precursors 

E. Condensable PM Emissions 

F. Prevention of Significant Deterioration 

(PSD) Program Requirements 

1. How must BACT be implemented for 

PM2.5? 

2. How does EPA plan to address PM2.5

Increments, Significant Impact Levels 

(SILs), and Significant Monitoring 

Concentrations (SMCs)? 

3. What is the ambient air quality analysis 

requirement for PM2.5? 

4. How must the PSD preconstruction 

monitoring requirement be implemented 

for PM2.5? 

G. Nonattainment New Source Review (NA 

NSR) Requirements 

1. What is the required offset ratio for 

direct PM2.5 emissions? 

2. Which precursors are subject to the 

offset requirement? 

3. What is the required offset ratio for PM2.5

precursors? 

4. Is interpollutant trading allowable to 

comply with offset requirements? 

H. How will the transition to the PM2.5 PSD 

requirements occur? 

1. Background 

2. Transition for ‘‘Delegated States’’ 

3. Transition for ‘‘SIP-Approved States’’ 

I. How will the transition to the PM2.5 NA 

NSR requirements occur? 

1. Background 

2. Transition 


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1 In this proposal, the terms ‘‘we,’’ ‘‘us,’’ and 

‘‘our,’’ refer to the EPA and the terms ‘‘you,’’ and 

‘‘your,’’ refer to the owners or operators of 

stationary sources of air pollution. 

2The Act uses the terms ‘‘major emitting facility’’ 

to refer to sources subject to the PSD program, and 

‘‘major stationary source’’ to refer to sources subject 

to NA NSR. See CAA sections 165, 169, 172(c)(5), 

and 302(j). For ease of reference, we use the term 

‘‘major source’’ to refer to both terms. 

3The term ‘‘criteria pollutant’’ means a pollutant 

for which we have set a NAAQS. 

4 In addition, the PSD program applies to most 

noncriteria regulated pollutants. 

3. Implementation of NSR Under the 

‘‘Emissions Offset Interpretative Ruling’’ 

(40 CFR part 51, appendix S) with 

Revisions 

J. Does major NSR apply to PM2.5

precursors during the SIP development 

period? 

K. Are there any Tribal concerns? 

L. What are the requirements for minor 

NSR for PM2.5? 

M. Rural Transport Areas 

VI. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review 

B. Paperwork Reduction Act 

C. Regulatory Flexibility Act 

D. Unfunded Mandates Reform Act 

E. Executive Order 13132—Federalism 

F. Executive Order 13175—Consultation 

and Coordination with Indian Tribal 

Governments 

G. Executive Order 13045—Protection of 

Children from Environmental Health and 

Safety Risks 

H. Executive Order 13211—Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer and 

Advancement Act 

J. Executive Order 12898—Federal Actions 

to Address Environmental Justice in 

Minority Populations and Low-Income 

Populations 

K. Congressional Review Act 

L. Petitions for Judicial Review 

M. Determination Under Section 307(d) 

VII. Statutory Authority 

II. Purpose 

The purpose of this rulemaking is to 

finalize the major NSR program 

provisions for PM2.5. This final rule 

supplements the final implementation 

rule for PM2.5 (excluding the NSR 

provisions) that we 1 promulgated on 

April 25, 2007 at 72 FR 20586. This 

final action on the bulk of the major 

NSR program for PM2.5 along with our 

proposed rule on increments, SILs, and 

SMC, when final, will represent the 

final elements necessary to implement a 

PM2.5 PSD program. When both rules are 

promulgated and in effect, the PM2.5

PSD program will no longer use a PM10

program as a surrogate, as has been the 

practice under our existing guidance. 

III. Background 

A. New Source Review (NSR) Program 

The existing regulations require both 

major and minor NSR programs to 

address any pollutant for which there is 

a National Ambient Air Quality 

Standard (NAAQS) and precursors to 

the formation of such pollutant when 

identified for regulation by the 

Administrator. This final rule amends 

the NSR regulations to establish the 

minimum elements for State, local, and 

Tribal agency programs implementing 

NSR for the PM2.5 NAAQS. This 

preamble also explains what interim 

provisions would apply with respect to 

PM2.5 during the State Implementation 

Plan (SIP) development period. 

The NSR program is a preconstruction 

permitting program that applies when a 

source is constructed or modified. The 

NSR program is composed of three 

different programs: 

• Prevention of Significant 

Deterioration (PSD); 

• Nonattainment NSR (NA NSR); and 

• Minor NSR. 

We often refer to the PSD and NA NSR 

programs together as the major NSR 

program because these programs 

regulate only major sources.2

The PSD program applies when a 

major source that is located in an area 

that is designated as attainment or 

unclassifiable for any criteria pollutant 

is constructed or undergoes a major 

modification.3 4 The NA NSR program 

applies when a major source that is 

located in an area that is designated as 

nonattainment for any criteria pollutant 

is constructed or undergoes a major 

modification. The minor NSR program 

addresses both major and minor sources 

that undertake construction or 

modification activities that do not 

qualify as major, and it applies 

regardless of the designation of the area 

in which a source is located. 

The national regulations that apply to 

each of these programs are located in 

the Code of Federal Regulations (CFR) 

as shown in the following table: 

Program Applicable regulations 

PSD .......................................................................................................... 40 CFR 52.21, 40 CFR 51.166, 40 CFR 51.165(b). 

NA NSR .................................................................................................... 40 CFR 52.24, 40 CFR 51.165, 40 CFR part 51, appendix S. 

Minor NSR ................................................................................................ 40 CFR 51.160–164. 

The PSD requirements include but are 

not limited to: 

• Installation of Best Available 

Control Technology (BACT); 

• Air quality monitoring and 

modeling analyses to ensure that a 

project’s emissions will not cause or 

contribute to a violation of any NAAQS 

or maximum allowable pollutant 

increase (PSD increment); 

• Notification of Federal Land 

Manager of nearby Class I areas; and 

• Public comment on the permit. 

Nonattainment NSR requirements 

include but are not limited to: 

• Installation of Lowest Achievable 

Emission Rate (LAER) control 

technology; 

• Offsetting new emissions with 

creditable emissions reductions; 

• Certification that all major sources 

owned and operated in the State by the 

same owner are in compliance with all 

applicable requirements under the Act; 

• An alternative siting analysis 

demonstrating that the benefits of the 

proposed source significantly outweigh 

the environmental and social costs 

imposed as a result of its location, 

construction, or modification; and 

• Public comment on the permit. 

Minor NSR programs must meet the 

statutory requirements in section 

110(a)(2)(C) of the Act, which requires 

‘‘* * * regulation of the modification 

and construction of any stationary 

source * * * as necessary to assure that 

national ambient air quality standards 

are achieved.’’ 

B. Fine Particulate Matter and the 

NAAQS for PM2.5

Fine particles in the atmosphere are 

made up of a complex mixture of 

components. Common constituents 

include sulfate (SO4); nitrate (NO3); 

ammonium; elemental carbon; a great 

variety of organic compounds; and 

inorganic material (including metals, 

dust, sea salt, and other trace elements) 

generally referred to as ‘‘crustal’’ 

material, although it may contain 

material from other sources. Airborne 

particulate matter (PM) with a nominal 

aerodynamic diameter of 2.5 

micrometers or less (a micrometer is 


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5Available in the docket for this rulemaking, ID 

No. EPA–HQ–OAR–2003–0062, and at http:// 

www.epa.gov/region07/programs/artd/air/nsr/ 

nsrmemos/pm25.pdf. 

6Available in the docket for this rulemaking, ID. 

No. EPA–HQ–OAR–2003–0062, and at http:// 

www.epa.gov/nsr/documents/nsrmemo.pdf. 

one-millionth of a meter, and 2.5 

micrometers is less than one-seventh the 

average width of a human hair) are 

considered to be ‘‘fine particles,’’ and 

are also known as PM2.5. ‘‘Primary’’ 

particles are emitted directly into the air 

as a solid or liquid particle (e.g., 

elemental carbon from diesel engines or 

fire activities, or condensable organic 

particles from gasoline engines). 

‘‘Secondary’’ particles (e.g., sulfate and 

nitrate) form in the atmosphere as a 

result of various chemical reactions. 

The health effects associated with 

exposure to PM2.5 are significant. 

Epidemiological studies have shown a 

significant correlation between elevated 

PM2.5 levels and premature mortality. 

Other important effects associated with 

PM2.5 exposure include aggravation of 

respiratory and cardiovascular disease 

(as indicated by increased hospital 

admissions, emergency room visits, 

absences from school or work, and 

restricted activity days), lung disease, 

decreased lung function, asthma attacks, 

and certain cardiovascular problems. 

Individuals particularly sensitive to 

PM2.5 exposure include older adults, 

people with heart and lung disease, and 

children. 

On July 18, 1997, we revised the 

NAAQS for PM to add new standards 

for fine particles, using PM2.5 as the 

indicator. We established health-based 

(primary) annual and 24-hour standards 

for PM2.5 (62 FR 38652). We set an 

annual standard at a level of 15 

micrograms per cubic meter (μg/m3) and 

a 24-hour standard at a level of 65 μg/ 

m3. At the time we established the 

primary standards in 1997, we also 

established welfare-based (secondary) 

standards identical to the primary 

standards. The secondary standards are 

designed to protect against major 

environmental effects of PM2.5 such as 

visibility impairment, soiling, and 

materials damage. 

On October 17, 2006, we revised the 

primary and secondary NAAQS for 

PM2.5 and PM10. In that rulemaking, we 

reduced the 24-hour NAAQS for PM2.5

to 35 μg/m3 and retained the existing 

annual PM2.5 NAAQS of 15 μg/m3. In 

addition, we retained PM10 as the 

indicator for coarse PM, retained the 

existing PM10 24-hour NAAQS of 150 

μg/m3, and revoked the annual PM10

NAAQS (which had previously been set 

at 50 μg/m3). See 71 FR 61236. 

C. Implementation of NSR for PM2.5

After we promulgated the NAAQS for 

PM2.5 in 1997, we issued a guidance 

document entitled ‘‘Interim 

Implementation for the New Source 

Review Requirements for PM2.5’’ (John 

S. Seitz, EPA, October 23, 1997).5 As 

noted in that guidance, section 165 of 

the Act suggests that PSD requirements 

become effective for a new NAAQS 

upon the effective date of the NAAQS. 

Section 165(a)(1) of the Act provides 

that no new or modified major source 

may be constructed without a PSD 

permit that meets all of the section 

165(a) requirements with respect to the 

regulated pollutant. Moreover, section 

165(a)(3) provides that the emissions 

from any such source may not cause or 

contribute to a violation of any NAAQS. 

Also, section 165(a)(4) requires BACT 

for each pollutant subject to PSD 

regulation. The 1997 guidance stated 

that sources would be allowed to use 

implementation of a PM10 program as a 

surrogate for meeting PM2.5 NSR 

requirements until certain difficulties 

were resolved, primarily the lack of 

necessary tools to calculate the 

emissions of PM2.5 and related 

precursors, the lack of adequate 

modeling techniques to project ambient 

impacts, and the lack of PM2.5

monitoring sites. 

On April 5, 2005, we issued a 

guidance document entitled 

‘‘Implementation of New Source Review 

Requirements in PM–2.5 Nonattainment 

Areas’’ (Stephen D. Page, EPA).6 This 

memorandum provides guidance on the 

implementation of the nonattainment 

major NSR provisions in PM2.5

nonattainment areas in the interim 

period between the effective date of the 

PM2.5 NAAQS designations (April 5, 

2005) and the promulgation date of the 

final NSR regulations reflected in this 

action. Besides affirming the 

continuation of the Seitz guidance 

memo in PM2.5 attainment areas, the 

April 5, 2005 memo recommends that 

until we promulgate the PM2.5 major 

NSR regulations, States should use a 

PM10 nonattainment major NSR program 

as a surrogate to address the 

requirements of nonattainment major 

NSR for PM2.5. 

On November 1, 2005, we proposed a 

rule to implement the 1997 PM2.5

NAAQS, including proposed revisions 

to the NSR program (70 FR 65984). As 

discussed above, this action finalizes 

the portion of that proposal related to 

NSR. The other portions of that 

proposal, concerning attainment dates, 

SIP submittals, reasonable further 

progress (RFP) requirements, etc., were 

finalized on April 25, 2007 (72 FR 

20586). 

On September 21, 2007, we proposed 

additional elements for the PSD 

program for PM2.5 including PM2.5

‘‘increments,’’ significant impact levels 

(SILs), and significant monitoring 

concentrations (SMCs) (72 FR 54112). 

Increments are the maximum allowable 

increases over baseline concentrations 

that can be permitted to occur when a 

major source is constructed or modified. 

This is one mechanism by which the 

PSD program prevents significant 

deterioration in air quality. A SIL 

defines the level of ambient air impact 

that is considered a ‘‘significant 

contribution’’ to air quality. If the 

modeled maximum ambient impacts of 

a new source or modification are below 

the SILs, the source: (1) Is presumed not 

to cause or contribute significantly to a 

PSD increment or NAAQS violation, 

and (2) is not required to perform the 

multiple-source, cumulative impacts 

assessments that are otherwise required 

under PSD. An SMC defines the level of 

modeled ambient air impact below 

which the reviewing authority may 

exempt a new or modified source from 

conducting the preconstruction 

monitoring that may otherwise be 

required under PSD. The reviewing 

authority may also exempt the source 

from preconstruction monitoring if the 

existing monitored ambient 

concentration is less than the SMC. This 

final action on the bulk of the major 

NSR program for PM2.5 along with our 

proposed rule on increments, SILs, and 

SMC, when final, will represent the 

final elements necessary to implement a 

PM2.5 PSD program. When both rules are 

promulgated and in effect, the PM2.5

PSD program will no longer use a PM10

program as a surrogate, as has been the 

practice under our existing guidance. 

IV. Overview of This Final Action 

The table below summarizes the main 

elements of the existing NSR program 

that this action addresses for PM2.5 as a 

regulated NSR pollutant. The table 

indicates our final position on an issue 

and whether our position has changed 

based on comments received. Our final 

action for each element, or where 

appropriate, explanation of 

implementation under existing 


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7See ‘‘Implementation of the New Source Review 

(NSR) Program for Particulate Matter Less Than 2.5 

Micrometers in Diameter (PM2.5); Response to 

Comments,’’ U.S. Environmental Protection 

Agency. It can be viewed or downloaded at 

www.regulations.gov, Docket ID No. EPA–HQ– 

OAR–2003–0062. 

regulations, is addressed in detail in the 

referenced sections of this preamble. 

NSR program element Final action Section 

Applicability to PM2.5 precursors ............. SO2—Must be regulated as precursor, NOX—Presumed regulated, VOC—Presumed not regulated, Ammonia—Presumed not regulated.V.A 

PSD major source threshold ................... 100/250 tons per year (tpy) .................................................................................... V.B 

NA NSR major source threshold ............ 100 tpy .................................................................................................................... V.B 

Significant emissions rate ....................... Direct PM2.5 emissions—10 tpy, SO2 precursor—40 tpy, NOX precursor—40 tpy, 

if regulated.

V.C & V.D 

Condensable PM2.5 emissions ................ Included in direct PM2.5 emissions for major NSR applicability determinations 

after the end of the transition period (changed based on comments received).

V.E 

Control technology: BACT and LAER ..... Applies for direct PM2.5 emissions, SO2, and other precursors if regulated. V.F.1 & V.G 

Prevention of significant deterioration ..... Increments, SILs and SMCs covered in a separate rulemaking ........................... V.F.2 

Air quality impact analysis ...................... Applies for PM2.5 ..................................................................................................... V.F.3 

Preconstruction monitoring ..................... Applies for PM2.5 (finalizing options 1 & 3) ............................................................ V.F.4 

NA NSR Statewide compliance and alternative siting analyses.Applies for direct PM2.5 emissions and precursors, if regulated ............................ V.G 

NA NSR offsets ....................................... Applies for direct PM2.5 emissions and precursors, if regulated ............................ V.G.1–3 

Interpollutant offsetting ............................ Allowed on a regional or statewide basis; EPA is issuing guidance with recommended regional hierarchies and trading ratios (changed based on comments received).V.G.4 

Transition for PSD ................................... Continues to use PM10 as a surrogate ................................................................... V.H 

Transition for NA NSR ............................ Applies through an approved SIP or through 40 CFR part 51, appendix S .......... V.I 

SIP development period .......................... Clarifies that major NSR does not apply to precursors during the SIP development period in attainment areas (changed based on comments received).V.J 

Tribal concerns ........................................ Cross references to proposed NSR rules for Indian country ................................. V.K 

Minor NSR ............................................... Clarifies that State and local regulatory programs must include PM2.5 requirements for minor sources.V.L 

NSR transport option .............................. Transport classification not available ..................................................................... V.M 

The provisions of the PM2.5 major 

NSR program finalized in this action are 

codified as revisions in the previously 

existing regulatory text. The revisions to 

NA NSR are codified in 40 CFR 51.165 

and appendix S to 40 CFR part 51. The 

PSD revisions are codified in 40 CFR 

51.166 and 52.21. 

V. Rationale for Final Actions 

In this section we discuss each 

element of our proposal for this 

rulemaking, explain our final action, 

discuss the rationale for our final action, 

and summarize the major public 

comments we received. The full 

summary of public comments on the 

proposal, along with our responses, can 

be found in the docket for this 

rulemaking.7

A. Applicability of NSR to Precursors of 

PM2.5 in the Ambient Air 

Scientific research has shown that 

various pollutants can contribute to 

ambient PM2.5 concentrations. In 

addition to direct PM2.5 emissions, these 

include the following precursors: 

• Sulfur dioxide (SO2); 

• Oxides of nitrogen (NOX); 

• Volatile organic compounds (VOC); 

and 

• Ammonia. 

These gas-phase precursors undergo 

chemical reactions in the atmosphere to 

form secondary PM. Formation of 

secondary PM depends on numerous 

factors including the concentrations of 

precursors; the concentrations of other 

gaseous reactive species; atmospheric 

conditions including solar radiation, 

temperature, and relative humidity; and 

the interactions of precursors with 

preexisting particles and with cloud or 

fog droplets. Several atmospheric 

aerosol species, such as ammonium 

nitrate and certain organic compounds, 

are semi-volatile and are found in both 

gas and particle phases. Given the 

complexity of PM formation processes, 

new information from the scientific 

community continues to emerge to 

improve our understanding of the 

relationship between sources of PM 

precursors and secondary particle 

formation. 

Precursors contribute significantly to 

ambient PM2.5 concentrations, 

producing approximately half of the 

concentration nationally. In most areas 

of the country, PM2.5 precursor 

emissions are major contributors to 

ambient PM2.5 concentrations. The 

relative contribution to ambient PM2.5

concentrations from each of these 

pollutants varies by area. The relative 

effect of reducing emissions of these 

pollutants is also highly variable. 

Some PM2.5 precursors are already 

subject to major NSR under other 

NAAQS, as shown in the following 

table: 

PM2.5

precursor 

Existing program coverage 

for major NSR applicability 

NOX ................ NA NSR and PSD for NO2

and Ozone. 

SO2 ................ NA NSR and PSD for SO2. 

VOC ............... NA NSR and PSD for 

Ozone. 

Ammonia ........ No coverage for NSR. 

In the subsections that follow, we first 

discuss our legal authority under the 

Act for regulating precursors to the 

formation of criteria pollutants, and 

then discuss our final action for each of 

the PM2.5 precursors. 

1. What is EPA’s legal authority to 

regulate precursors? 

As we discussed in the November 1, 

2005 proposal, we interpret the Act to 

not only provide explicit authority for 

EPA to regulate precursors, but also to 

grant us discretion to determine how to 

address precursors for particular 

regulatory purposes. This reading is 

based on section 302(g) of the Act, 

which defines the term ‘‘air pollutant’’ 

to include ‘‘any precursors to the 

formation of any air pollutant, to the 

extent the Administrator has identified 

such precursor or precursors for the 

particular purpose for which the term 

‘air pollutant’ is used.’’ The first clause 

of this second sentence in section 302(g) 

explicitly authorizes the Administrator 


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to identify and regulate precursors as air 

pollutants under other parts of the Act. 

In addition, the second clause of the 

sentence indicates that the 

Administrator has discretion to identify 

which pollutants should be classified as 

precursors for particular regulatory 

purposes. Thus, we do not necessarily 

construe the Act to require that EPA 

identify a particular precursor as an air 

pollutant for all regulatory purposes 

where it can be demonstrated that 

various programs under the Act address 

different aspects of the air pollutant 

problem. Likewise, we do not interpret 

the Act to require that EPA treat all 

precursors of a particular pollutant the 

same under any one program when 

there is a basis to distinguish between 

such precursors within that program. 

For example, in a recent rule addressing 

PM2.5 precursors for purposes of the 

transportation conformity program, we 

chose to adopt a different approach for 

one precursor based on the limited 

emissions of that precursor from onroad 

mobile sources and the degree to which 

it contributes to PM2.5 concentrations 

(70 FR 24280, May 6, 2005). 

Other provisions of the Act reinforce 

our reading of section 302(g) to mean 

that Congress intended precursors to 

NAAQS pollutants to be subject to the 

air quality planning and control 

requirements of the Act, but also 

recognized that there may be 

circumstances where it is not 

appropriate to subject precursors to 

certain requirements of the Act. Section 

182 of the Act provides for the 

regulation of NOX and VOC as 

precursors to ozone in ozone 

nonattainment areas, but also provides 

in section 182(f) that major stationary 

sources of NOX (an ozone precursor) are 

not subject to emission reduction 

requirements for ozone where the State 

shows through modeling that NOX

reductions do not decrease ozone. 

Section 189(e) provides for the 

regulation of PM10 precursors in PM10

nonattainment areas, but also recognizes 

that there may be certain circumstances 

(e.g., if precursor emission sources do 

not significantly contribute to PM10

levels) where it is not appropriate to 

apply control requirements to PM10

precursors. The legislative history of 

section 189(e) recognized the 

complexity behind the science of 

precursor transformation into PM10

ambient concentrations and the need to 

harmonize the regulation of PM10

precursors with other provisions of the 

Act: 

The Committee notes that some of these 

precursors may well be controlled under 

other provisions of the CAA. The Committee 

intends that * * * the Administrator will 

develop models, mechanisms, and other 

methodology to assess the significance of the 

PM10 precursors in improving air quality and 

reducing PM10. Additionally, the 

Administrator should consider the impact on 

ozone levels of PM10 precursor controls. The 

Committee expects the Administrator to 

harmonize the PM10 reduction objective of 

this section with other applicable regulations 

of this CAA regarding PM10 precursors, such 

as NOX. 

See H. Rpt. 101–490, Pt. 1, at 268 (May 

17, 1990), reprinted in S. Prt. 103–38, 

Vol. II, at 3292. 

In summary, section 302(g) of the Act 

clearly calls for the regulation of 

precursor pollutants, but the Act also 

identifies circumstances when it may 

not be appropriate to regulate precursors 

and gives the Administrator discretion 

to determine how to address particular 

precursors under various programs 

required by the Act. Due to the 

complexities associated with precursor 

emissions and their variability from 

location to location, we believe that in 

certain situations it may not be effective 

or appropriate to control a certain 

precursor under a particular regulatory 

program or for EPA to require similar 

control of a particular precursor in all 

areas of the country. 

The term ‘‘air pollutant,’’ as defined 

in section 302(g), is incorporated into 

the NSR provisions for various 

purposes. Thus, we interpret section 

302(g) of the Act to require us to 

consider how to address precursors 

under the NSR program. 

With regard to PSD, section 165(a)(3) 

of the Act states that new or modified 

major sources must demonstrate that 

emissions ‘‘will not cause, or contribute 

to, air pollution in excess of any * * * 

NAAQS in any air quality control region 

* * *.’’ A source could not reasonably 

make this demonstration without 

considering precursors that EPA has 

identified for this purpose. Section 

165(a)(4) of the Act states that a new or 

modified source must apply BACT ‘‘for 

each pollutant subject to regulation 

under this Act emitted from, or which 

results from, such facility.’’ The phrase 

‘‘emitted from, or which results from’’ 

indicates that the statute is not limited 

to direct emissions, but rather extends 

to precursors as well. 

With regard to NA NSR, sections 

172(c)(4) and 173 require States to 

demonstrate, among other things, that 

emissions from new or modified major 

sources are consistent with the 

achievement of ‘‘reasonable further 

progress.’’ Reasonable further progress 

is further defined as reductions of the 

relevant air pollutant, which is defined 

in section 302(g) to include precursors 

identified by EPA as subject to 

regulation for that purpose. 

2. What is EPA’s approach for 

addressing precursors? 

As proposed, we are finalizing 

different approaches for addressing the 

individual precursors to PM2.5 under the 

Act’s NSR provisions. Generally, where 

the scientific data and modeling 

analyses provide reasonable certainty 

that the pollutant’s emissions are a 

significant contributor to ambient PM2.5

concentrations, we believe that 

pollutant should be identified as a 

‘‘regulated NSR pollutant’’ and subject 

to the PM2.5 NSR provisions. 

Conversely, where the effect of a 

pollutant’s emissions on ambient PM2.5

concentrations is subject to substantial 

uncertainty, such that in some 

circumstances the pollutant may not 

result in formation of PM2.5, or control 

of the pollutant may have no effect or 

may even aggravate air quality, we 

generally believe it is unreasonable to 

establish a nationally-applicable 

presumption that the pollutant is a 

regulated NSR pollutant subject to the 

requirements of NSR for PM2.5. We 

discuss our final action with respect to 

each of the PM2.5 precursors and the 

basis for that action in sections V.A.2 

through 5. 

For those precursors that are either 

presumed to be regulated or not 

regulated (NOX, VOC, and ammonia), a 

State program need not follow the 

presumed approach if it can be 

demonstrated that the precursor in 

question is not, or is, a ‘‘significant 

contributor’’ to PM2.5 concentrations 

within the specific area. ‘‘Significant 

contribution’’ in this context is a 

different concept than that in section 

110(a)(2)(D) of the Act. Section 

110(a)(2)(D) of the Act prohibits States 

from emitting air pollutants in amounts 

which significantly contribute to 

nonattainment or other air quality 

problems in other States. Consistent 

with the previous discussion of sections 

189(e) and 302(g), we are clarifying that 

the use in this NSR implementation rule 

of the term ‘‘significant contribution’’ to 

the area’s PM2.5 concentration means 

that a significant change in emissions of 

the precursor from sources in the area 

would be projected to provide a 

significant change in PM2.5

concentrations in the area. For example, 

if modeling indicates that a reduction in 

an area’s NOX emissions would reduce 

ambient PM2.5 levels in the area, but that 

a reduction in ammonia emissions 

would result in virtually no change in 

ambient PM2.5 levels, this would suggest 

that NOX is a significant contributor but 

that ammonia is not. We are not 


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establishing in this rule a quantitative 

test for determining whether PM2.5

levels in an area change significantly in 

response to reductions in precursor 

emissions in the area. However, in 

considering this question, it is relevant 

to consider that relatively small 

reductions in PM2.5 levels are estimated 

to result in worthwhile public health 

benefits. 

This approach to identifying a 

precursor as a regulated NSR pollutant 

reflects atmospheric chemistry 

conditions in the area and the 

magnitude of emissions of the precursor 

in the area. Assessments of whether it 

is technically feasible and cost effective 

to control particular emissions units at 

a source should be part of the later 

BACT determination within a permit 

action, and should occur after the basic 

assessment of which precursors are to 

be regulated NSR pollutants in an area 

is completed. 

Most commenters did not question 

our legal authority to identify and 

regulate PM2.5 precursors. However, 

some commenters argued, based on the 

language of sections 302(g) and 189(e) of 

the Act, that once we have designated 

a compound as a precursor, we do not 

have discretion to presumptively 

exclude it from NSR requirements. 

Other commenters on this issue 

indicated that we do have such 

discretion, based on the de minimis 

doctrine of the Alabama Power decision 

or on practical implementation 

considerations such as the uncertainty 

in measuring and modeling the effect of 

PM2.5 precursors. 

We do not agree with the comment 

that the Act does not give us discretion 

to presumptively exclude a PM2.5

precursor from NSR requirements. As 

stated previously, we believe that 

section 302(g) allows the Administrator 

to presumptively not require certain 

precursors to be addressed in PM2.5 NSR 

programs generally, while allowing the 

State or EPA to make a finding for a 

specific area to override the general 

presumption. In the following pollutantspecific sections of this preamble, we 

find that at this time there is sufficient 

uncertainty regarding whether certain 

precursors significantly contribute to 

PM2.5 concentrations in all areas such 

that the policy set forth in this rule does 

not presumptively require certain 

precursors (ammonia, VOC) to be 

controlled in each area. However, the 

State or EPA may reverse the 

presumption and regulate a precursor if 

it provides a demonstration showing 

that the precursor is a significant 

contributor to PM2.5 concentrations in 

the area. In addition, if in the State’s 

NSR program adoption process a 

commenter provides additional 

information suggesting an alternative 

policy for regulating a particular 

precursor, the State will need to 

respond to this information in its 

rulemaking action. 

Hence, we continue to believe that the 

Act provides us the authority not only 

to identify and regulate precursors to 

PM2.5, but also to treat precursors of the 

same pollutant differently under the 

same program. 

3. Final Action on SO2

Sulfur dioxide is emitted mostly from 

the combustion of fossil fuels in boilers 

operated by electric utilities and other 

industrial sources. Less than 20 percent 

of SO2 emissions nationwide are from 

other sources, mainly other industrial 

processes such as oil refining and pulp 

and paper production. The formation of 

sulfuric acid from the oxidation of SO2

is an important process affecting most 

areas in North America. There are three 

different pathways for this 

transformation. 

First, gaseous SO2 can be oxidized by 

the hydroxyl radical (OH) to create 

sulfuric acid. This gaseous SO2

oxidation reaction occurs slowly and 

only in the daytime. Second, SO2 can 

dissolve in cloud water (or fog or 

rainwater), and there it can be oxidized 

to sulfuric acid by a variety of oxidants, 

or through catalysis by transition metals 

such as manganese or iron. If ammonia 

is present and taken up by the water 

droplet, then ammonium sulfate will 

form as a precipitate in the water 

droplet. After the cloud changes and the 

droplet evaporates, the sulfuric acid or 

ammonium sulfate remains in the 

atmosphere as a particle. This aqueous 

phase production process involving 

oxidants can be very fast; in some cases 

all the available SO2 can be oxidized in 

less than an hour. Third, SO2 can be 

oxidized in reactions in the particlebound water in the aerosol particles 

themselves. This process takes place 

continuously, but only produces 

appreciable sulfate in alkaline (dust, sea 

salt) coarse particles. Oxidation of SO2

has also been observed on the surfaces 

of black carbon and metal oxide 

particles. During the last 20 years, much 

progress has been made in 

understanding the first two major 

pathways, but some important questions 

still remain about the smaller third 

pathway. Models indicate that more 

than half of the sulfuric acid in the 

eastern United States and in the overall 

atmosphere is produced in clouds. 

The sulfuric acid formed from these 

pathways reacts readily with ammonia 

to form ammonium sulfate, (NH4)2SO4. 

If there is not enough ammonia present 

to fully neutralize the produced sulfuric 

acid (one molecule of sulfuric acid 

requires two molecules of ammonia), 

part of it exists as ammonium bisulfate; 

NH4HSO4 (one molecule of sulfuric acid 

and one molecule of ammonia) and the 

particles are more acidic than 

ammonium sulfate. In certain situations 

(in the absence of sufficient ammonia 

for neutralization), sulfate can exist in 

particles as sulfuric acid, H2SO4. 

Sulfuric acid often exists in the plumes 

of stacks where SO2, sulfur trioxide 

(SO3), and water vapor are in much 

higher concentrations than in the 

ambient atmosphere, but these 

concentrations become quite small as 

the plume is cooled and diluted by 

mixing. 

Because sulfate is a significant 

component (e.g., ranging from 9 percent 

to 40 percent) of PM2.5 concentrations, 

and contributes to other air quality 

problems in all regions of the country, 

we proposed to require States to treat 

SO2 as a PM2.5 precursor in all areas. We 

are retaining the same approach for SO2

in this final rule. Sulfate is an important 

precursor to PM2.5 formation in all areas, 

and has a strong regional impact on 

PM2.5 concentrations. This approach is 

consistent with past EPA regulations, 

such as the Clean Air Interstate Rule 

(CAIR), the Clean Air Visibility Rule, 

the Acid Rain rules, and the Regional 

Haze rule, each of which require SO2

reductions to address fine particle 

pollution and related air quality 

problems. Finally, we do not believe 

that regulating SO2 as a precursor to 

PM2.5 is likely to add a major burden to 

sources, as SO2 is already regulated as 

part of the NSR program for the SO2

NAAQS. 

Most commenters who addressed this 

issue agreed that SO2 should be 

regulated as a PM2.5 precursor, although 

one only supported regulation of SO2 as 

a precursor in NA NSR, and not under 

PSD. Two commenters disagreed that 

SO2 acts as precursors to PM2.5 in all 

cases and indicated that it should not be 

regulated as an ‘‘always-in’’ precursor. 

We find the commenters’ arguments 

against regulating SO2 as a precursor 

unpersuasive. Sulfate is a significant 

fraction of PM2.5 mass in all 

nonattainment areas currently, and 

although large SO2 reductions are 

projected from electric generating units 

with the implementation of the CAIR 

program, sulfate is still projected to be 

a key contributor to PM2.5

concentrations in the future, in both 

attainment and nonattainment areas. 

Sulfur dioxide emissions also lead to 

sulfate formation on both regional and 

local scales. 


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4. Final Action on NOX

The sources of NOX are numerous and 

widespread. The combustion of fossil 

fuel generates the majority of NOX

emissions, with large contributions from 

power generation and mobile sources. 

Nitrates are formed from the oxidation 

of NOX into nitric acid (HNO3) either 

during the daytime (reaction with OH) 

or during the night (reactions with 

ozone and water). Nitric acid 

continuously transfers between the gas 

and the condensed phases through 

condensation and evaporation processes 

in the atmosphere. However, unless it 

reacts with other species (such as 

ammonia, sea salt, or dust) to form a 

neutralized salt, it will volatilize and 

not be measured using standard PM2.5

measurement techniques. The formation 

of aerosol ammonium nitrate is favored 

by the availability of ammonia, low 

temperatures, and high relative 

humidity. Because ammonium nitrate is 

semivolatile and not stable in higher 

temperatures, nitrate levels are typically 

lower in the summer months and higher 

in the winter months. The resulting 

ammonium nitrate is usually in the submicrometer particle size range. 

Reactions with sea salt and dust lead to 

the formation of nitrates in coarse 

particles. Nitric acid may be dissolved 

in ambient aerosol particles. 

Based on a review of speciated 

monitoring data analyses, it is apparent 

that nitrate concentrations vary 

significantly across the country. For 

example, in some southeastern 

locations, annual average nitrate levels 

are in the range of 6 to 8 percent of total 

PM2.5 mass, whereas nitrate comprises 

40 percent or more of PM2.5 mass in 

certain California locations. Nitrate 

formation is favored by the availability 

of ammonia, low temperatures, and high 

relative humidity. It is also dependent 

upon the relative degree of nearby SO2

emissions because ammonia reacts 

preferentially with SO2 over NOX. 

Reductions in NOX emissions are 

expected to reduce PM2.5 concentrations 

in most areas. However, it has been 

suggested that in a limited number of 

areas, NOX control would result in 

increased PM2.5 mass by disrupting the 

ozone cycle and leading to increased 

oxidation of SO2 to form sulfate 

particles, which are heavier than nitrate 

particles. 

Because of these factors, we are 

finalizing our proposed approach to 

NOX as a precursor to PM2.5 for the NSR 

program. Under this approach, NOX is 

presumed to be a significant contributor 

to ambient PM2.5 concentrations in all 

PSD and NA NSR areas. However, a 

State or EPA may rebut this 

presumption for a specific area if the 

State demonstrates to the 

Administrator’s satisfaction or EPA 

demonstrates that NOX emissions in that 

area are not a significant contributor to 

that area’s ambient PM2.5

concentrations. If a State or EPA makes 

such a demonstration, NOX would not 

be considered a PM2.5 precursor under 

the NSR program in that area. If a State 

or EPA does not make such a 

demonstration, NOX must be regulated 

as a precursor under the PSD, NA NSR, 

and minor source programs for PM2.5. 

As discussed previously, this 

‘‘presumed-in’’ approach is warranted 

based on the well-known transformation 

of NOX into nitrates, coupled with the 

fact that nitrate concentrations vary 

significantly around the country. This 

approach is consistent with other recent 

EPA regulations requiring NOX

reductions, which will reduce fine 

particle pollution, such as the CAIR and 

a number of rules targeting onroad and 

nonroad engine emissions. 

We had proposed that NOX be 

presumed to be a precursor in any State 

that EPA has identified as a source of 

the PM2.5 interstate transport problem. 

In the final rule, we have dropped this 

requirement to be consistent with EPA’s 

Clean Air Fine Particle Implementation 

Rule published on April 25, 2007. 72 FR 

20586. Such a requirement is not 

necessary in this rule because States 

that contribute to downwind 

nonattainment for PM2.5 are otherwise 

required to address transported NOX

emissions under the CAIR. 

In areas where NOX is regulated as a 

precursor to PM2.5, we do not believe 

that this is likely to add a major burden 

to sources, as NOX is already a regulated 

NSR pollutant. This is because NOX is 

an identified precursor for the ozone 

NAAQS and an indicator for the NO2

NAAQS. 

Several commenters agreed that NOX

should be regulated under major NSR as 

a precursor to PM2.5. Some of these 

commenters believe that States should 

not have the opportunity to demonstrate 

otherwise, or indicated that a waiver for 

exclusion of NOX as a precursor should 

be allowed only if downwind States 

approve such a waiver. A few 

commenters stated that NOX should not 

be regulated as a precursor to PM2.5 in 

the major NSR program, either on 

grounds of scientific uncertainty 

regarding the impact of NOX emissions 

on ambient PM2.5 concentrations or on 

policy grounds (i.e., because NOX is 

already regulated under NSR for other 

NAAQS). 

We are not persuaded by the 

argument that NOX should not be 

regulated as a PM2.5 precursor because 

it is a regulated pollutant under other 

NAAQS. We do not find the degree of 

scientific uncertainty regarding PM2.5

formation from NOX to be great enough 

to preclude regulation of NOX as a 

precursor with an opportunity for a 

case-by-case demonstration that NOX is 

not a significant contributor. 

Furthermore, the fact that we regulate 

NOX for other NAAQS under the NSR 

program does not by itself justify 

declining to regulate NOX as a PM2.5

precursor in circumstances where NOX

also significantly contributes to PM2.5

formation. As noted earlier, the 

regulation of NOX as a precursor for 

PM2.5 is not expected to add a major 

burden to regulated sources that are 

already required to limit NOX emission 

to meet other NAAQS. 

We disagree with the commenters 

who believe that emissions of NOX

cannot be correlated to PM2.5 formation, 

or that it is unclear when NOX acts as 

a precursor. As discussed previously, 

our decision to regulate NOX as a 

precursor to PM2.5 is based on the wellknown transformation of NOX into 

nitrates. Nevertheless, nitrate 

concentrations vary significantly across 

the country. As a result, we believe that 

the ‘‘presumed-in’’ approach is 

appropriate for NOX since a State can 

demonstrate that NOX should not be a 

precursor in a given area or region. 

While we recognize that NOX

emissions can affect PM2.5

concentrations in downwind areas, we 

disagree that approval from downwind 

States should be required for a State to 

exclude NOX as a PM2.5 precursor for a 

particular area. This is because States 

that contribute to downwind 

nonattainment for PM2.5 are otherwise 

required to address transported NOX

emissions under the CAIR. 

5. Final Action on VOC 

The organic component of ambient 

particles is a complex mixture of 

hundreds or even thousands of organic 

compounds. These organic compounds 

are either emitted directly from sources 

(i.e., primary organic aerosol) or can be 

formed by reactions in the ambient air 

(i.e., secondary organic aerosol, or 

SOA). Volatile organic compounds are 

key precursors in the formation 

processes for both SOA and ozone. The 

relative importance of organic 

compounds in the formation of 

secondary organic particles varies from 

area to area, depending upon local 

emissions sources, atmospheric 

chemistry, and season of the year. 

The lightest organic molecules (i.e., 

molecules with six or fewer carbon 

atoms) occur in the atmosphere mainly 

as vapors and typically do not directly 


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form organic particles at ambient 

temperatures due to the high vapor 

pressure of their products. However, 

they participate in atmospheric 

chemistry processes resulting in the 

formation of ozone and certain free 

radical compounds (such as OH) which 

in turn participate in oxidation 

reactions to form SOA, sulfates, and 

nitrates. These VOCs include all alkanes 

with up to six carbon atoms (from 

methane to hexane isomers), all alkenes 

with up to six carbon atoms (from 

ethene to hexene isomers), benzene, and 

many low-molecular weight carbonyls, 

chlorinated compounds, and 

oxygenated solvents. 

Intermediate weight organic 

molecules (i.e., compounds with 7 to 24 

carbon atoms) often exhibit a range of 

volatilities and can exist in both the gas 

and aerosol phase at ambient 

conditions. For this reason they are also 

referred to as semivolatile compounds. 

Semivolatile compounds react in the 

atmosphere to form SOA. These 

chemical reactions are accelerated in 

warmer temperatures, and studies show 

that SOA typically comprises a higher 

percentage of carbonaceous PM in the 

summer as opposed to the winter. The 

production of SOA from the 

atmospheric oxidation of a specific VOC 

depends on four factors: Its atmospheric 

abundance, its chemical reactivity, the 

availability of oxidants (ozone, OH, 

HNO3), and the volatility of its products. 

In addition, recent work suggests that 

the presence of acidic aerosols may lead 

to an increased rate of SOA formation. 

Aromatic compounds such as toluene, 

xylene, and trimethyl benzene are 

considered to be the most significant 

anthropogenic SOA precursors and have 

been estimated to be responsible for 50 

to 70 percent of total SOA in some 

airsheds. Man-made sources of 

aromatics gases include mobile sources, 

petrochemical manufacturing, and 

solvents. Some of the biogenic 

hydrocarbons emitted by trees are also 

considered to be important precursors of 

secondary organic PM. Terpenes (and bpinene, limonene, carene, etc.) and the 

sesquiterpenes are expected to be major 

contributors to SOA in areas with 

significant vegetation cover, but 

isoprene is not. Terpenes are very 

prevalent in areas with pine forests, 

especially in the southeastern United 

States. The rest of the anthropogenic 

hydrocarbons (higher alkanes, paraffins, 

etc.) have been estimated to contribute 

5 to 20 percent to the SOA 

concentration depending on the area. 

The contribution of the primary and 

secondary components of organic 

aerosol to the measured organic aerosol 

concentrations remains a complex issue. 

Most of the research performed to date 

has been done in southern California, 

and more recently in central California, 

while fewer studies have been 

completed on other parts of North 

America. Many studies suggest that the 

primary and secondary contributions to 

total organic aerosol concentrations are 

highly variable, even on short time 

scales. Studies of pollution episodes 

indicate that the contribution of SOA to 

the organic PM can vary from 20 percent 

to 80 percent during the same day. 

Despite significant advances in 

understanding the origins and 

properties of SOA, it remains probably 

the least understood component of 

PM2.5. The reactions forming secondary 

organics are complex, and the number 

of intermediate and final compounds 

formed is voluminous. Some of the best 

efforts to unravel the chemical 

composition of ambient organic aerosol 

matter have resulted in quantifying the 

concentrations of hundreds of organic 

compounds representing only 10 to 20 

percent of the total organic aerosol 

mass. For this reason, SOA continues to 

be a significant topic of research and 

investigation. 

Current scientific and technical 

information shows that carbonaceous 

material is a significant fraction of total 

PM2.5 mass in most areas, that certain 

VOC emissions are precursors to the 

formation of SOA, and that a 

considerable fraction of the total 

carbonaceous material originates from 

local as opposed to regional sources. 

However, while significant progress has 

been made in understanding the role of 

gaseous organic material in the 

formation of organic PM, this 

relationship remains complex. We 

recognize that further research and 

technical tools are needed to better 

characterize emissions inventories for 

specific VOC, and to determine the 

extent of the contribution of specific 

VOC to organic PM mass. 

As a result, this final rule does not, in 

general, require regulation of VOC as a 

precursor to PM2.5 for the NSR program. 

However, a State may demonstrate to 

the Administrator’s satisfaction or EPA 

may demonstrate that VOC emissions in 

a specific area are a significant 

contributor to that area’s ambient PM2.5

concentrations. After such a 

demonstration, the State would regulate 

VOC (or a subset of VOC) as a PM2.5

precursor for the NSR program in that 

area. That is, the State would need to 

regulate construction and modification 

of stationary sources that increase 

emissions of VOC in that area to assure 

that these emissions do not interfere 

with reasonable further progress or the 

ability of that area to attain or maintain 

the PM2.5 NAAQS. 

We believe that this ‘‘presumed-out’’ 

approach is appropriate for VOC 

because of the complexity in assessing 

the role of VOC in PM2.5 formation, as 

discussed previously. Where the effect 

of a pollutant’s emissions on ambient 

PM2.5 concentrations is subject to this 

degree of uncertainty, we do not have 

justification to establish a nationallyapplicable presumption that the 

pollutant is a regulated NSR pollutant 

subject to the requirements of NSR for 

PM2.5. Under the circumstances, we 

believe the best policy is to continue to 

regulate VOC under NSR as a precursor 

to ozone in all areas, which will 

potentially provide a co-benefit for 

PM2.5 concentrations despite the 

uncertainty in PM2.5 formation from 

VOC. As discussed previously, we do 

not find it appropriate to utilize the 

same approach for NOX because the 

scientific data and modeling analyses 

provide more certainty that NOX

emissions are a significant contributor 

to ambient PM2.5 concentrations. 

Note that we intend to regulate high 

molecular weight VOC (with 25 carbon 

atoms or more and low vapor pressure) 

as direct PM2.5 emissions because they 

are emitted directly as primary organic 

particles and exist primarily in the 

condensed phase at ambient 

temperatures. See section V.E following 

for more on the regulation of such 

‘‘condensables.’’ 

Most commenters agreed with the 

‘‘presumed-out’’ approach for VOC. One 

commenter said that the role of VOC in 

the formation of PM2.5 is sufficiently 

understood to recommend a ‘‘waiver’’ 

approach for this pollutant in the same 

way as NOX is treated for PM2.5 in the 

rule. 

As discussed previously, the reactions 

forming secondary organics are complex 

and the number of intermediate and 

final compounds formed is voluminous. 

Some of the best efforts to unravel the 

chemical composition of ambient 

organic aerosol matter have merely been 

able to quantify the concentrations of 

hundreds of organic compounds 

representing only 10 to 20 percent of the 

total organic aerosol mass. For this 

reason, SOA continues to be a 

significant topic of research and 

investigation. Accordingly, we do not 

agree with the commenter who 

suggested a waiver or ‘‘presumed-in’’ 

approach for VOC. We continue to 

believe that our ‘‘presumed-out’’ 

approach is most appropriate for VOC 

and have included this approach in the 

final rules. 


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8NARSTO (2004) ‘‘Particulate Matter Assessment 

for Policy Makers: A NARSTO Assessment.’’ P. 

McMurry, M. Shepherd, and J. Vickery, eds. 

Cambridge University Press, Cambridge, England. 

ISBN 0 52 184287 5. See the docket for this 

rulemaking, Docket ID No. EPA–HQ–OAR–2003– 

0062, or http://www.narsto.org/section.src?SID=6. 

6. Final Action on Ammonia 

Ammonia (NH3) is a gaseous pollutant 

that is emitted by natural and 

anthropogenic sources. Emissions 

inventories for ammonia are considered 

to be among the most uncertain of any 

species related to PM. Ammonia serves 

an important role in neutralizing acids 

in clouds, precipitation, and particles. 

In particular, ammonia neutralizes 

sulfuric acid and nitric acid, the two key 

contributors to acid deposition (acid 

rain). Deposited ammonia also can 

contribute to problems of eutrophication 

in water bodies, and deposition of 

ammonium particles may effectively 

result in acidification of soil as 

ammonia is taken up by plants. The 

NARSTO Fine Particle Assessment 8

indicates that reducing ammonia 

emissions where sulfate concentrations 

are high may reduce PM2.5 mass 

concentrations, but may also increase 

the acidity of particles and 

precipitation. An increase in particle 

acidity is suspected to be linked with 

adverse human health effects and with 

an increase in the formation of 

secondary organic compounds. Based 

on this information and further insights 

gained from the NARSTO Fine Particle 

Assessment, it is apparent that the 

formation of particles related to 

ammonia emissions is a complex, 

nonlinear process. 

Though recent studies have improved 

our understanding of the role of 

ammonia in aerosol formation, ongoing 

research is required to better describe 

the relationships between ammonia 

emissions, PM concentrations, and 

related impacts. The control techniques 

for ammonia and the analytical tools to 

quantify the impacts of reducing 

ammonia emissions on atmospheric 

aerosol formation are both evolving. 

Also, area-specific data are needed to 

evaluate the effectiveness of reducing 

ammonia emissions on reducing PM2.5

concentrations in different areas, and to 

determine where ammonia decreases 

may increase the acidity of particles and 

precipitation. 

Due to the considerable uncertainty 

related to ammonia as a precursor, our 

final rules do not require ammonia to be 

regulated as a PM2.5 precursor but do 

give States the option to regulate 

ammonia as a precursor to PM2.5 in 

nonattainment areas for purposes of 

NSR on a case-by-case basis. Consistent 

with our proposal, if a State 

demonstrates to the Administrator’s 

satisfaction that ammonia emissions in 

a specific nonattainment area are a 

significant contributor to that area’s 

ambient PM2.5 concentrations, the State 

would regulate ammonia as a PM2.5

precursor under the NSR program in 

that nonattainment area. Once this 

demonstration is made, ammonia would 

be a ‘‘regulated NSR pollutant’’ under 

NA NSR for that particular 

nonattainment area, and the State would 

need to regulate construction and 

modification of stationary sources that 

increase emissions of ammonia in that 

area to assure that these emissions do 

not interfere with reasonable further 

progress or the ability of that area to 

attain or maintain the PM2.5 NAAQS. In 

all other nonattainment areas in that 

State and nationally, ammonia would 

not be subject to the NSR program. In 

addition, the action of any State 

identifying ammonia emissions as a 

significant contributor to a 

nonattainment area’s PM2.5

concentrations, or our approval of a 

nonattainment SIP doing so, does not 

make ammonia a regulated NSR 

pollutant for the purposes of PSD in any 

attainment or unclassifiable areas 

nationally. This is consistent with our 

proposal (70 FR 66036) and no 

commenters took issue with the 

proposal. We also retain the ability to 

make a technical demonstration for any 

area in a State, if appropriate, to reverse 

the presumption and require ammonia 

to be addressed in that State’s 

nonattainment area plan. 

We elected to finalize the proposed 

approach because of continued 

uncertainties regarding ammonia 

emission inventories and the effects of 

ammonia emission reductions. 

Ammonia emission inventories are 

presently very uncertain in most areas, 

complicating the task of assessing 

potential impacts of ammonia emissions 

reductions. In addition, data necessary 

to understand the atmospheric 

composition and balance of ammonia 

and nitric acid in an area are not widely 

available, making it difficult to predict 

the results of potential ammonia 

emission reductions. Ammonia 

reductions may be effective and 

appropriate for reducing PM2.5

concentrations in selected locations, but 

in other locations such reductions may 

lead to minimal reductions in PM2.5

concentrations and increased 

atmospheric acidity. Research projects 

continue to expand our collective 

understanding of these issues, but at 

this time we believe this case-by-case 

approach for nonattainment areas is 

appropriate given that there is sufficient 

uncertainty regarding the impact of 

ammonia emission reductions on PM2.5

concentrations in all nonattainment 

areas. In light of these uncertainties, we 

encourage States to continue efforts to 

better understand the role of ammonia 

in their fine particle problem areas. 

Several commenters agreed with our 

‘‘presumed-out’’ approach for ammonia. 

One of these commenters recommended 

that we recognize the role ammonia 

plays in PM2.5 formation and develop a 

policy to require the minimization and 

mitigation of known emissions of 

ammonia, while another suggested that 

we require States to initiate 

comprehensive ambient air monitoring 

networks to determine the extent of 

local effects of ammonia. 

Four commenters did not support 

treating ammonia as a PM2.5 precursor 

under any circumstances. Three of these 

commenters stated that if EPA permits 

States to demonstrate that ammonia 

should be regulated as a PM2.5 precursor 

for NSR purposes, we should make clear 

that ammonia emissions from the 

operation of an air pollution control 

system to control NOX should not factor 

into such a demonstration. 

Two commenters preferred that we 

use the ‘‘presumed-in’’ approach for 

ammonia, as for NOX. One of these 

commenters stated that the ‘‘presumedout’’ approach would improperly 

delegate our authority to regulate 

ammonia as a PM2.5 precursor to the 

States and would reverse Congress’ 

requirement to regulate PM precursors 

unless the emissions are not part of the 

problem, instead taking the approach 

that we will ‘‘not regulate unless proven 

to be part of the problem.’’ 

We continue to believe that the 

‘‘presumed-out’’ approach is most 

appropriate for ammonia. As discussed 

previously, considerable uncertainties 

remain regarding ammonia emission 

inventories and the effects of ammonia 

emission reductions. As a result, we do 

not believe it advisable to adopt a 

‘‘presumed-in’’ approach. However, 

where a State can gather sufficient data 

to demonstrate that reductions in 

ammonia emissions will decrease 

ambient concentrations of PM2.5 in a 

particular nonattainment area, we 

believe that the State should be allowed 

to regulate ammonia emissions under its 

PM2.5 NSR program for that area. 

We do not believe that this approach 

improperly delegates authority to the 

States. The final rule establishes a 

general presumption for all 

nonattainment areas through this 

rulemaking process, and allows for the 

presumption to be modified by the State 

on a case-by-case basis with EPA 

approval. Under the Clean Air Fine 


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9See ‘‘NEI–PM2.5 Source Analysis’’ in the docket 

for this rulemaking, Docket ID No. EPA–HQ–OAR– 

2003–0062. 

Particle Implementation Rule (72 FR 

20586, April 5, 2007) (addressing 

various nonattainment plan elements 

other than NSR), we still retain the 

ability to make a technical 

demonstration for any area if 

appropriate to reverse the presumption 

and require ammonia to be addressed in 

its nonattainment area plan. As 

discussed previously in section V.A.1, 

we interpret the Act to allow the 

‘‘presumed-out’’ approach adopted in 

the final rule. 

We agree with the commenter who 

suggested that we continue research on 

the role of ammonia in the formation of 

PM2.5. We believe that it is prudent to 

continue research on ammonia control 

technologies and the ammonia-sulfatenitrate-SOA equilibrium before 

undertaking a broad national program to 

reduce ammonia emissions. As we 

develop a greater understanding about 

the potential air quality effects of 

reducing ammonia emissions in specific 

nonattainment areas, it may be 

appropriate for ammonia reduction 

strategies to be included in future SIPs. 

At this time, however, we believe that 

reducing SO2 and NOX emissions will 

achieve significant reductions in 

ambient PM2.5 concentrations. 

Regarding the comment related to 

ammonia emissions from NOX control 

systems, we believe that a State should 

evaluate all sources of ammonia 

emissions when determining whether to 

regulate ammonia under its PM2.5 NSR 

program for a particular nonattainment 

area. However, we also encourage States 

to be mindful of the potential tradeoff in 

terms of ambient PM2.5 concentrations 

that may be related to reducing 

ammonia emissions from NOX control 

systems. 

B. Major Stationary Source Threshold 

for PM2.5

The major NSR program applies to 

construction of major stationary sources 

and major modifications at major 

stationary sources. A stationary source 

is a ‘‘major source’’ if its actual 

emissions or its potential to emit for a 

specific pollutant equals or exceeds the 

major source threshold for that pollutant 

established in the Act. Different 

pollutants, including precursors, are not 

summed to determine applicability. 

Sections 169 and 302(j) of the Act 

contain definitions of ‘‘major emitting 

facility’’ and ‘‘major stationary source’’ 

that apply to programs implemented 

under part C and subpart 1 of part D of 

the Act (PSD and NA NSR, 

respectively). Consistent with our 

proposal, these final rules follow these 

definitions for purposes of defining a 

major emitting facility or major 

stationary source that would be subject 

to major NSR. The thresholds set out in 

the definitions are applied to each 

relevant pollutant individually, that is, 

to direct PM2.5 emissions and to 

emissions of each pollutant identified as 

a PM2.5 precursor for the applicable NSR 

program. Under the final rules, the 

major source thresholds are as follows: 

PSD ............. 100 tpy for source categories 

listed in 40 CFR 

51.166(b)(1)(i)(a) and 

52.21(b)(1)(i)(a). 

250 tpy for all other source 

categories. 

NA NSR ...... 100 tpy for all source categories. 

No regulatory change is required to 

implement this approach to the major 

source thresholds for direct PM2.5

emissions and the PM2.5 precursors. See 

40 CFR 51.165(a)(1)(iv)(a), 

51.166(b)(1)(i), 52.21(b)(1)(i), and part 

51, appendix S, section II.A.4. 

This approach is consistent with how 

we treat other criteria pollutants that are 

covered by subpart 1 of part D of the 

Act. Nonattainment NSR programs 

under subpart 1 do not include a tiered 

classification system such as the one 

required for ozone nonattainment areas 

under subpart 2 of part D. We do not 

interpret subpart 4 of part D of the Act 

(creating ‘‘serious’’ and ‘‘moderate’’ 

classifications for PM10 nonattainment 

areas) as applying to PM2.5. 

Although our approach is consistent 

with sections 169 and 302(j) and subpart 

1 of part D of the Act, it results in a 

higher major source threshold in PM2.5

nonattainment areas than the major 

source threshold that applies in some 

PM10 nonattainment areas under subpart 

4 of part D of the Act. This is because 

section 189(b) of the Act establishes a 

70-tpy major source threshold for 

‘‘serious’’ PM10 nonattainment areas 

while ‘‘moderate’’ PM10 nonattainment 

areas apply a 100-tpy major source 

threshold based on the definition in 

section 302(j). We do not believe the Act 

gives us the discretion to promulgate a 

lower major source threshold for 

pollutants such as PM2.5 that are only 

subject to subpart 1 of part D of the Act. 

Our emissions inventory data do not 

indicate that this situation will 

adversely impact attainment of the 

PM2.5 NAAQS. These data indicate that 

a significant number of sources have 

actual PM2.5 emissions in the 100 to 250 

tpy range. Additionally, our more 

current inventory data show that the 

number of sources that would be 

covered as major sources by a lower 

major source threshold would not 

increase substantially unless the 

threshold were lowered to 20 tpy or 

below. Thus, even if EPA had the 

discretion to adopt a 70-tpy major 

source threshold for PM2.5

nonattainment areas, our data indicate 

that few additional sources would be 

subject to the major NSR program in 

PM2.5 nonattainment areas.9

We believe that States should 

consider such information in 

developing their own SIP-approved NSR 

programs. For example, if construction 

of PM2.5 sources emitting 99 tpy with no 

major NSR controls and without 

mitigation would undermine a State’s 

ability to achieve reasonable further 

progress or attain the PM2.5 NAAQS, the 

State should consider imposing 

emissions controls or other 

requirements on these sources through 

the State’s minor NSR program. Note 

that such programs are required under 

the existing statute and regulations to 

assure that the NAAQS are achieved. 

See section 110(a)(2)(C) of the Act and 

40 CFR 51.160. In addition, States may 

address such sources through other 

elements in their nonattainment area 

SIPs that are not statutorily bound to the 

definition of major source, as the major 

NSR program is. We reiterate that since 

we do not interpret subpart 4 of the Act 

to apply to PM2.5, we do not believe that 

we have discretion under section 302(j) 

of the Act to define a lower major source 

threshold for pollutants such as PM2.5

that are only subject to subpart 1 of part 

D of the Act. 

Some commenters indicated that State 

minor NSR programs would not be 

sufficient to address such sources due to 

interstate transport and the existence of 

interstate PM2.5 nonattainment areas. 

These commenters indicated that a 

lower major source threshold for PM2.5

sources located in designated 

nonattainment areas should be applied 

uniformly throughout the entire 

nonattainment area, which would not be 

possible when minor NSR programs are 

defined on a State-by-State basis. 

We believe, to the contrary, that States 

can coordinate their minor NSR 

programs to address interstate PM2.5

nonattainment areas, and we encourage 

them to do so. In addition, we note that 

the impacts of direct PM2.5 emissions 

are generally felt primarily in the local 

area. 

One commenter stated that in order to 

address the impact of high PM 

concentrations, the Act mandates EPA 

to define a criteria pollutant’s NSR 

major threshold at levels less than 100 

tpy. The commenter gave the example of 


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10For additional background on EPA’s 

interpretation of modification and rationale for 

including significant emissions rates in defining major modifications, see 61 FR 38253–54 (Dec. 31, 

2002). 

subparts 2 and 4 of part D of the Act, 

which define lower major source 

thresholds for certain classifications of 

ozone and PM10 nonattainment areas, 

respectively. The commenter argued 

that it is unreasonable for us to assert 

that subpart 4 does not apply to this rule 

because it regulates all PM with a 

diameter of less than 10 micrometers, 

which includes PM2.5. The commenter 

believes that we recognized as much in 

our proposal preamble discussion of the 

options for implementing reasonably 

available control technology (RACT), 

where we discussed potential 

approaches that ‘‘would be consistent 

with the approach set forth in the Act 

in subpart 4.’’ 70 FR 66017. This 

commenter stated that a reasonable 

interpretation of the Act requires major 

sources of direct PM2.5 emissions and 

precursor emissions to be defined at a 

baseline level of 70 tpy, and adjusted 

further downward as appropriate 

considering the characteristics and 

potential impacts of the pollutants. 

We do not agree that subpart 4 of part 

D applies to PM2.5 nonattainment areas. 

Subpart 4 was added to the Act by 

Congress specifically to address the 

PM10 NAAQS. We believe that the PM2.5

standard should be implemented under 

subpart 1 of part D, which is the general 

provision of the Act related to NAAQS 

implementation. Part D of title I of the 

Act sets forth the requirements for SIPs 

needed to attain the NAAQS. Part D also 

includes a general provision under 

subpart 1, which applies to all NAAQS 

for which a specific subpart does not 

exist. Because the PM2.5 standards were 

not established until 1997, the 

nonattainment plan provisions found in 

section 172 of subpart 1 apply. Subpart 

4 on its face applies only to the PM10

standard. In general, the emphasis in 

subpart 4 on reducing PM10

concentrations from certain sources of 

direct PM2.5 emissions can be somewhat 

effective in certain PM2.5 nonattainment 

areas but not in all. Contributions to 

PM2.5 concentrations are typically from 

a complex mix of sources of primary 

emissions and sources of precursor 

emissions, which form particles through 

reactions in the atmosphere. In addition, 

PM2.5 differs from PM10 in terms of 

atmospheric dispersion characteristics, 

chemical composition, and contribution 

from regional transport. 

A group of environmental 

commenters believed that EPA should 

be consistent with the stationary source 

size thresholds proposed for RACT in 

option 2, see 70 FR 66019/1. In our 

proposal preamble discussion of RACT, 

while we discussed developing a 

classification system for PM2.5

nonattainment areas under section 

172(a)(1) of subpart 1, we did not 

discuss subjecting PM2.5 to the 

requirements of subpart 4. While our 

discussion of RACT contemplated a 

lower threshold for RACT applicability 

in some PM2.5 nonattainment areas, we 

did not characterize this as defining a 

lower major source threshold. Moreover, 

section 302(j) defines a major stationary 

source as one that emits 100 tpy or more 

‘‘except as otherwise expressly 

provided.’’ Since section 172 does not 

expressly provide EPA with the 

authority to promulgate a major source 

threshold below 100 tpy, we do not 

believe we are authorized to do so under 

subpart 1 of part D of the Act. 

One commenter stated that the major 

source threshold for PM2.5 emissions 

should be calculated using the current 

SO2 and NOX definitions of major 

source and significant emissions rate. 

Specifically, the commenter suggested 

that the ratio of these values (100 tpy 

and 40 tpy, respectively) should be 

multiplied by the significant emissions 

rate for direct PM2.5 emissions (10 tpy; 

see section V.C following) to yield a 

PM2.5 major source threshold of 25 tpy. 

As previously stated, we do not 

believe that we have discretion under 

the Act to define a lower major source 

threshold under subpart 1 of part D of 

the Act. In any case, the major source 

thresholds and significant emissions 

rates for SO2 and NOX were not defined 

in relation to one another, and therefore 

their relationship would not provide a 

suitable basis for developing the PM2.5

major source threshold from the PM2.5

significant emissions rate. Major source 

thresholds are defined directly in the 

Act, while the significant emissions 

rates were codified independently in 

regulations through a modeling analysis 

of ambient impacts. 

C. Significant Emissions Rate for Direct 

Emissions of PM2.5

The determination of what should be 

classified as a modification subject to 

major NSR is based, in part, on a 

‘‘significant emissions rate.’’ 10 The 

major NSR regulations define this term 

as a rate above which a net emissions 

increase will trigger major NSR 

permitting requirements, if the increase 

results from a major modification. 

Sources are exempt from major NSR 

requirements if the emissions increase 

resulting from a modification is below 

this rate because EPA considers such 

lower emissions increases to be de 

minimis for purposes of the major NSR 

program. 

The significant emissions rates for the 

criteria pollutants other than PM2.5 are 

given in the following table: 

Criteria pollutant Significant emissions rate (tpy) 

Ozone ................................................................. VOC: Any increase up to 40 tpy (dependent on NA classification). 

NOX: Any increase up to 40 tpy (dependent on NA classification). 

NO2 ..................................................................... NOX: 40 tpy. 

Particulate Matter ................................................ 25 tpy, particulate matter emissions. 

15 tpy, PM10 emissions. 

CO ....................................................................... 50 or 100 tpy (dependent on NA classification). 

SO2 ..................................................................... 40 tpy. 

Lead .................................................................... 0.6 tpy. 

Significant emissions rates for 

additional (non-criteria) pollutants that 

are subject to the PSD program are 

contained in 40 CFR 51.166(b)(23) and 

40 CFR 52.21(b)(23). 

For direct emissions of PM2.5, these 

final rules define the significant 

emissions rate as 10 tpy. This is the 

level that we proposed as our preferred 

option. This final significant emissions 

rate for direct PM2.5 emissions is based 

fundamentally on the same approach 

that we used in setting the previous 

significant emissions rates for PM 

emissions and PM10 emissions. 

Historically, the original significant 

emissions rate for PM (25 tpy of PM 

emissions) was set using a modeling 

analysis to determine the amount of PM 

emissions that a source could emit that 


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11The EPA established the original NAAQS for 

PM in terms of ambient concentrations of TSP (40 

CFR 51.100(ss)). Source applicability for PM was 

determined in terms of amounts of PM emissions 

(40 CFR 51.100(pp)) from the affected source. In 

1993, at 58 FR 31622 (see page 31629), EPA 

eliminated TSP as the ambient indicator for 

measuring compliance with both the NAAQS and 

PSD increments. Thus, EPA no longer considers the 

TSP ambient indicator to be a regulated NSR 

pollutant. The EPA is currently evaluating whether 

it remains appropriate to consider PM as a 

‘‘regulated NSR pollutant.’’ There is no NAAQS for 

TSP/PM, rather the standards address specific size 

fractions of PM, namely PM10 and PM2.5. However, 

PM emissions, based on in-stack measurements, 

continue to be regulated under PSD because of the 

use of such emissions for evaluating compliance 

under a variety of CAA section 111 new source 

performance standards (40 CFR part 60). Given the 

regulatory changes and positions taken by EPA 

since 1993, EPA is re-evaluating the implications 

for PM emissions in the NSPS program (and other 

air programs) and will act accordingly to clarify this 

issue in the near-term. 

would be unlikely to cause ambient 

impacts above 4 percent of the PM 

NAAQS (measured as total suspended 

particulate (TSP)).11 Although a range of 

source configurations can yield a wide 

range of impacts per tpy of emissions, 

our review of typical configurations of 

major PM sources led us to the 

conclusion that a major modification 

that increased PM emissions by 25 tpy 

or less would be unlikely to increase 24- 

hour average concentrations of TSP by 

more than 4 percent of the 24-hour TSP 

NAAQS. Subsequently, when we set the 

significant emissions rate for PM10, we 

adjusted the rate for PM emissions using 

the ratio of the 24-hour PM10 NAAQS to 

the 24-hour TSP NAAQS to derive the 

PM10 significant emissions rate of 15 

tpy. We used the ratio of 24-hour 

NAAQS for this adjustment because that 

NAAQS was controlling for both PM 

and PM10. 

We used a conceptually similar 

methodology to derive the final PM2.5

significant emissions rate from the rate 

for PM10. However, because the 24-hour 

NAAQS is not controlling for PM2.5, we 

revised the methodology to take into 

account the annual impact of emissions. 

See the proposal preamble for 

additional information on the 

methodology we used to develop the 

final significant emissions rate for direct 

PM2.5 emissions (70 FR 66038). 

Several commenters supported our 

approach to setting the significant 

emissions rate for direct PM2.5 emissions 

and the level (10 tpy) based on the same 

methodology used for PM emissions and 

PM10 emissions. Numerous other 

commenters believe that our 

methodology was too conservative, and 

suggested a significant emissions rate of 

15 tpy. Two commenters suggested that 

we use significant emissions rate of 5 

tpy or less. Another commenter 

suggested that we could ‘‘split the 

difference,’’ using an option that could 

give States and companies some 

flexibility: Modifications less than 5 tpy 

of direct PM2.5 emissions could be 

considered de minimis; modifications 

between 5 and 15 tpy of direct PM2.5

emissions could choose to either 

demonstrate less than a 4 percent 

NAAQS increase or simply be subject; 

and modifications with increases of 15 

or more tpy of direct PM2.5 emissions 

would be subject. 

We agree with commenters who 

indicated that we were correct in using 

the same methodology for direct PM2.5

that was used to set the significant 

emissions rate for PM10 and PM 

emissions. We do not agree that using 

the same level as PM10 emissions (15 

tpy) is warranted, given the 

demonstrated health effects of PM2.5. 

Neither do we agree that a significant 

emissions rate of 5 tpy or less is 

warranted. While our screening model 

runs indicated that emissions increases 

in this range at facilities with short 

stacks can cause measurable increases 

in ambient PM2.5 levels, we do not 

believe that facilities at the extremes 

should dictate the program for all 

sources. 

We do not agree that inclusion of 

condensable emissions in future testing 

and applicability determinations (see 

section V.E) is grounds for increasing 

the SER for direct PM2.5 emissions. The 

results of the modeling analysis that is 

the basis for the SER of 10 tpy is not 

affected by the nature of the direct PM2.5

emissions (i.e., condensable or not). 

We also do not agree that the 

proportions of primary and secondary 

PM2.5 that comprise ambient PM2.5

concentrations is relevant to 

determining the appropriate SER for 

direct PM2.5 emissions. Following our 

historic approach for PM and PM10, we 

based our analysis on determining the 

size of a source of direct PM2.5

emissions that would be expected to 

have an ambient impact of 4 percent or 

more of the NAAQS. This relationship 

holds true regardless of the origin of the 

particles that make up the ambient 

PM2.5. The commenter’s approach (i.e., 

carrying out the analysis based on onehalf of the NAAQS because primary 

PM2.5 makes up only one-half of the 

ambient PM2.5) implies that an increase 

in ambient PM2.5 concentrations due to 

an increase in direct PM2.5 emissions is 

somehow automatically matched by a 

like increase in the ambient 

concentration of secondary PM2.5. We 

do not believe that this is a reasonable 

approach. 

D. Significant Emissions Rates for PM2.5

Precursors 

Consistent with the preferred option 

in the proposal, we are setting 

significant emissions rates for PM2.5

precursors at the levels for those 

pollutants already included in major 

NSR programs, as shown in the 

following table: 

PM2.5

precursor 

Significant emissions 

rate (equal to or 

exceeding) 

SO2 ........................... 40 tpy. 

NOX .......................... 40 tpy. 

VOC .......................... 40 tpy. 

Ammonia ................... Adopted in SIP. 

VOC is presumed not to be a 

precursor to PM2.5 in any attainment or 

unclassifiable area, unless the State 

demonstrates to the Administrator’s 

satisfaction or EPA demonstrates that 

emissions of VOC from sources in a 

specific area are a significant 

contributor to that area’s ambient PM2.5

concentrations. Any State making such 

a demonstration would be required to 

adopt the 40-tpy significant emissions 

rate unless it demonstrates that a more 

stringent significant emissions rate 

(lower rate) is more appropriate. 

For ammonia, States determining in 

their SIPs that control of ammonia is a 

necessary part of a PM2.5 control strategy 

in a particular area must set the 

significant emissions rate for ammonia. 

Otherwise, according to the definition of 

‘‘significant’’ in the PSD program, ‘‘any 

emissions rate’’ would be considered 

significant. See 40 CFR 51.166(b)(23)(ii). 

One commenter stated that we should 

not leave it to States to set significant 

emissions rates for ammonia. The 

commenter argued that EPA’s scientists 

should shoulder this responsibility, and 

the resulting significant emissions rate 

should be subject to notice and 

comment. 

In the final rule, we are allowing 

those States that determine in their SIPs 

that control of ammonia is necessary to 

set the significant emissions rate for 

ammonia, based on the information 

developed for each attainment 

demonstration. At this time, we believe 

this is more appropriate than EPA 

setting a single, nationwide significant 

emissions rate because of the different 

role ammonia plays in the formation of 

PM2.5 from one area to another, as well 

as our still-evolving understanding of 

the impact of reducing ammonia 

emissions on ambient PM2.5

concentrations. In addition, we note that 

the SIP revisions that States undertake 

to add ammonia to their NA NSR 


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12Leter from Thompson G. Pace, Acting Chief, 

Particulate Matter Programs Branch, to Sean 

Fitzsimmons, Iowa Department of Natural 

Resources (Mar. 31, 1994) (available at http:// 

www.epa.gov/Region7/programs/artd/air/ 

nsr.nsrmemos/cpm.pdf and in the docket for this 

rulemaking, Docket ID No. EPA–HQ–OAR–2003– 

0062). 

programs are subject to notice and 

comment rulemaking procedures. 

Numerous commenters supported our 

proposal to set significant emissions 

rates for PM2.5 precursors at the levels 

already used for other purposes in the 

NSR program. One commenter indicated 

that since roughly half or more of 

ambient PM2.5 is derived from 

precursors, 10 tpy would be an 

appropriate significant emissions rate 

for PM2.5 precursor emissions. Another 

commenter suggested a significant 

emissions rate of 4 tpy for SO2 and 2 tpy 

for NOX, based on the percentage of 

PM2.5 that is typically derived from 

these precursors and the ratios between 

the existing significant emissions rates 

for these pollutants and the SO2 and 

NO2 annual NAAQS. Since the ambient 

concentrations of PM2.5 vary across the 

country and since significant emissions 

rates have not been developed as a ratio 

of the NAAQS, we do not believe that 

the suggested approach is appropriate. 

As discussed in the proposal, the use 

of existing significant emission rates 

where the PM2.5 precursor is also 

regulated under NSR as a separate 

criteria pollutant harmonizes the NSR 

program for PM2.5 with the NSR 

programs for those other criteria 

pollutants. This enables a source to 

determine the NSR impacts of proposed 

modifications by reference to a single 

significant emissions rate for each 

pollutant, and enables streamlining of 

determinations regarding the applicable 

control technology and analysis of air 

quality impacts into a single and 

comprehensive decision making process 

for both PM2.5 and other criteria 

pollutants that also cover PM2.5

precursors. This also follows precedent. 

When ozone became a criteria pollutant, 

EPA used the NOX significant emissions 

rate from the NO2 program. 

The burden imposed is not the only 

factor to consider when setting the 

significant emission rates for 

precursors—the process for determining 

the significant emission rates must also 

take into account the accuracy and 

certainty with which we can predict the 

effect of the precursors on PM2.5

concentrations. It is difficult to 

determine the ambient air quality effects 

that result from a single source of 

emissions of PM2.5 precursors. There are 

conservative screening models for 

predicting impacts of large NOX and 

SO2 sources on ambient PM2.5

concentrations. We conducted a range of 

modeling analyses to determine the 

amount of PM2.5 precursor emissions 

needed to show an increase in ambient 

PM2.5 concentrations. These analyses 

showed that precursor emissions 

probably have some localized impacts, 

but that most impact is farther 

downwind as precursors have the time 

to convert to PM2.5. In addition, the 

modeling available at this time does not 

provide sufficient information to 

estimate impacts of emissions from 

individual sources of ammonia and 

VOC on ambient PM2.5 concentrations. 

While we know that precursors 

contribute to the formation of PM2.5 in 

the ambient air, the degree to which 

these individual precursors contribute 

to PM2.5 formation in a given location is 

complex and variable. There are 

competing chemical reactions taking 

place in the atmosphere, and 

meteorological conditions play a 

significant role in the size and 

characteristics of particle formation. For 

these reasons, we do not believe that we 

have adequate data on the impacts of 

precursor emissions from individual 

sources to override the administrative 

advantages of setting the significant 

emissions rates for SO2, NOX, and VOC 

for purposes of the PM2.5 NSR program 

at the same levels that are already used 

for other purposes in the major NSR 

program. 

E. Condensable PM Emissions 

In this final NSR rule, EPA will not 

require that States address condensable 

PM in establishing enforceable 

emissions limits for either PM10 or PM2.5

in NSR permits until the completion of 

a transition period, as described herein. 

In response to significant comments on 

the variability of test methods available 

for measuring condensable emissions, 

we have adopted this transition period 

approach to allow us to assess the 

capabilities of the test methods and 

possibly revise them to improve 

performance. The transition period will 

end January 1, 2011 unless EPA 

advances this date through the 

rulemaking process described below. 

Subsequent to the completion of the 

test methods assessment, EPA will be 

conducting a notice and comment 

rulemaking to codify new or revised test 

methods. Once these new or revised test 

methods are in place, States will have 

the tools necessary to issue NSR permits 

addressing condensable PM. Thus, as 

part of the test methods rulemaking, we 

will take comment on an earlier closing 

date for the transition period in the NSR 

program if we are on track to meet our 

expectation to complete the test 

methods rule much earlier than January 

1, 2011. In the meantime, however, we 

are establishing January 1, 2011 as the 

latest possible end date for the NSR 

transition period because this is also the 

end of the transition period for SIP 

purposes as described in the Clean Air 

Fine Particle Implementation Rule (see 

section II.L in 72 FR 20586, April 25, 

2007). Prevention of Significant 

Deterioration and NA NSR permits 

issued after the effective date of this 

NSR implementation rule but prior to 

the end of the transition period for the 

NSR program are not required to 

account for condensable emissions in 

PM2.5 or PM10 emissions limits. After 

January 1, 2011 (or any earlier date 

established in the upcoming rulemaking 

codifying test methods), EPA will 

require that NSR permits include limits 

of condensable emissions, as 

appropriate. Prior to this date, States are 

not prohibited from establishing 

emissions limits in NSR permits that 

include the condensable fraction of 

direct PM2.5. 

As noted in the proposal preamble, 

certain commercial or industrial 

activities involving high temperature 

processes (e.g., fuel combustion, metal 

processing, and process cooking 

operations) emit gaseous pollutants into 

the ambient air, some of which rapidly 

condense into particle form. The 

constituents of these condensed 

particles include, but are not limited to, 

organic materials, sulfuric acid, and 

metals and metal compounds. We 

consider such condensable emissions to 

be a component of direct PM emissions. 

Specifically, direct PM emissions 

consist of both the ‘‘filterable fraction’’ 

which already exist in particle form at 

the elevated temperature of the exhaust 

stream, and the ‘‘condensable fraction’’ 

which exist in gaseous form under 

exhaust stream conditions but 

condenses rapidly in the ambient air. 

Because condensable PM emissions 

exist almost entirely in the 2.5 

micrometer range and smaller, these 

emissions are inherently more 

significant for PM2.5 than for prior PM 

standards addressing larger particles. 

Condensable PM emissions commonly 

make up a significant component of 

direct PM2.5 emissions. Therefore, we 

believe that it is important that the air 

quality management of PM promote a 

comprehensive approach to the control 

of condensable PM. 

We proposed on November 1, 2005 to 

clarify that condensable PM emissions 

must be included when determining 

whether a source is subject to the major 

NSR program. We noted in the proposal 

that our prior guidance 12 had clarified 

that PM10 includes condensable PM and 


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that, where States expect condensable 

PM emissions to be in higher amounts, 

States should use methods that 

appropriately measure condensable PM 

emissions. In addition, we pointed out 

that the 2001 consolidated emissions 

reporting rule (CERR) requires States to 

report condensable emissions in each 

inventory revision (see 67 FR 39602, 

June 10, 2001) and that Method 202 in 

appendix M of 40 CFR part 51 quantifies 

condensable PM. We also noted that 

States have not applied this existing 

guidance consistently. 

We received a number of comments 

on whether NSR programs should 

account for condensable PM emissions 

in light of the current state of knowledge 

of and uncertainties around the 

measurement of direct PM2.5. Several 

commenters supported our proposal to 

require the inclusion of condensable PM 

emissions in NSR applicability 

determinations. On the other hand, 

several other commenters expressed 

opposition to including condensables at 

this time and raised concerns about the 

availability and implementation of test 

methods and related issues about the 

uncertainties in existing data for 

condensable PM2.5. As a result of the 

concerns, these commenters believed 

EPA would be premature in requiring a 

comprehensive evaluation of 

condensable PM2.5, especially as it 

related to developing any new 

emissions limits for stationary sources. 

One commenter noted that regulation 

of condensable PM at this time will 

impede, rather than facilitate, 

expeditious attainment of the PM2.5

standard. Another commenter expressed 

concern about the potential for 

retroactive enforcement over 

applicability decisions made in good 

faith, and for retroactive application of 

the new test method to assert violations 

of an emission limit, where the 

applicability decision or the emission 

limit was originally based on flawed 

testing/estimating methodology. Several 

commenters raised serious concerns 

about the availability and 

implementation of accurate test 

methods and emissions factors for 

condensable PM2.5. They further stated 

that regulation of condensable PM2.5

emissions would be appropriate only 

after we have developed a workable 

transitional strategy that ensures 

existing major sources are not placed in 

‘‘NSR jeopardy’’ for physical and 

operational changes undertaken before 

new test methods and other 

requirements for condensable PM2.5 are 

established. 

In recognition of these concerns, both 

as they apply to the NSR program and 

the broader air program, we have 

adopted a transition period during 

which NSR permits need not address 

limits of condensable PM2.5 emissions. 

During this transition period, EPA will 

undertake a collaborative testing effort 

with industry, National Association of 

Clean Air Agencies (NACAA), and other 

stakeholders to assess and improve the 

effectiveness and accuracy of the 

available or revised test methods. The 

purpose of the stakeholder testing 

projects will be to collect new direct 

filterable and condensable PM2.5

emissions data using methodologies that 

provide data more representative of 

sources’ direct PM2.5 emissions. The 

EPA, States, and others will use these 

data to establish or improve emissions 

factors and to define more 

representative source emissions limits 

in permits. 

The EPA acknowledges the legitimate 

concerns raised by commenters 

concerning potential exposure to 

retroactive enforcement and has 

established rules to address this issue. 

The EPA will not revisit applicability 

determinations made in good faith prior 

to the end of the transition period, 

insofar as the quantity of condensable 

PM emissions are concerned, unless the 

applicable implementation plan clearly 

required consideration of condensable 

PM. Likewise, EPA will interpret PM 

emissions limitations in existing 

permits or permits issued during the 

transition period as not requiring 

quantification of condensable PM2.5 for 

compliance purposes unless such a 

requirement was clearly specified in the 

permit conditions or the applicable 

implementation plan. 

After the end of the transition period 

(January 1, 2011 or any earlier date 

established in the upcoming rulemaking 

codifying test methods), EPA will 

require that all NSR applicability 

determinations for PM2.5 and PM10

address condensable emissions as 

applicable, and the source may not rely 

on calculations made for previous 

determinations that did not include an 

accurate accounting of condensables. 

Additionally, compliance with these 

limits must be determined using the 

promulgated validated test methods that 

are applicable after that date. Moreover, 

after that date, we expect that 

condensable PM emissions will be 

addressed in all other aspects of the 

major NSR program, such as impact 

analyses under PSD and offsets under 

NA NSR. See 72 FR 20586, April 25, 

2007 for the discussion of the transition 

period as it applies to the other 

elements of the air program in the final 

Clean Air Fine Particle Implementation 

Rule. 

Although EPA is not requiring that 

State NSR programs address 

condensable emissions of PM until the 

end of the transition period, States that 

have developed the necessary tools are 

not precluded from acting to measure 

and control condensable PM emissions 

in NSR permit actions prior to the end 

of the transition period, especially if it 

is required in an applicable SIP. To the 

extent that a State has the supporting 

technical information and test methods, 

the State may assess the capabilities of 

current control technologies, possible 

modifications to such technologies, or 

new technologies as appropriate relative 

to control of condensable PM2.5

emissions. As an example, a specific 

approach for controlling condensable 

PM could be a change in control device 

operating temperature to improve 

emissions reductions. We also note that 

it is important that implementation of 

any new or revised emissions limits and 

test methods that account for 

condensable emissions should be 

prospective and clearly differentiated 

from existing NSR permit requirements. 

This will avoid confusion over the 

compliance status relative to existing 

PM emissions limits that were not 

developed considering the condensable 

portion. 

Notwithstanding the issues and 

uncertainties related to condensable 

PM, we encourage States to begin 

immediately to identify measures for 

reducing condensable PM emissions in 

major NSR permit actions, particularly 

where those emissions are expected to 

represent a significant portion of total 

PM emissions from a source. 

F. Prevention of Significant 

Deterioration (PSD) Program 

Requirements 

To receive a permit for a new major 

source or a major modification, sources 

subject to PSD must: 

• Install Best Available Control 

Technology (BACT). 

• Conduct air quality modeling to 

ensure that the project’s emissions will 

not cause or contribute to either— 

—A violation of any NAAQS or 

maximum allowable pollutant 

increase (PSD increment); or 

—An adverse impact on any Class I area 

‘‘air quality related value’’ (AQRV). 

• As required, comply with 

preconstruction monitoring 

requirements. 

This final action regarding each of these 

elements is discussed in the following 

sections. 


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1. How must BACT be implemented for 

PM2.5? 

We are not making any change to our 

current regulations or policy for 

implementing BACT requirements at a 

major source that is subject to the 

requirements of the PSD program. 

Accordingly, if a new major source will 

emit, or have the potential to emit, a 

significant amount of a regulated NSR 

pollutant in an attainment area for that 

pollutant, the source must apply BACT 

for each emissions unit that emits the 

pollutant. In addition, if a physical or 

operational change at an existing major 

source will result in a significant 

emissions increase and a significant net 

emissions increase of a regulated NSR 

pollutant in an attainment area for that 

pollutant, the source must apply BACT 

to each proposed emissions unit 

experiencing a net increase in emissions 

of that pollutant as a result of the 

physical or operational change in the 

unit. Under the PM2.5 PSD program, 

these requirements will apply to direct 

PM2.5 emissions; SO2 emissions; NOX

emissions, unless a State demonstrates 

that NOX is not a significant contributor 

to ambient PM2.5 concentrations in that 

area; and to VOC if identified by a State 

as a precursor in the PM2.5 attainment 

area where the source is located. 

2. How does EPA plan to address PM2.5

Increments, Significant Impact Levels 

(SILs), and Significant Monitoring 

Concentrations (SMCs)? 

On November 1, 2005, we proposed a 

rule to implement the PM2.5 NAAQS, 

including proposed revisions to the NSR 

program (70 FR 65984). In that proposal, 

we indicated our intent to propose a 

separate rule for developing PM2.5

increments, SILs, and SMCs and sought 

comments on general approaches for 

developing these values. We proposed 

PM2.5 increments, SILs, and SMCs in a 

rule dated September 21, 2007. 72 FR 

54112. We intend to address comments 

received on these components of the 

PM2.5 PSD program when we finalize 

that proposed rule. 

3. What is the ambient air quality 

analysis requirement for PM2.5? 

All sources subject to PSD review 

must perform an ambient air quality 

impact analysis to show that the 

emissions from the source will not 

cause or contribute to a PSD increment 

or NAAQS violation. See section 

165(a)(3) of the CAA; 40 CFR 51.166(k) 

and 52.21(k). We did not propose, and 

our final rules do not contain, any 

changes to the regulations on air quality 

impact analyses for purposes of the 

PM2.5 NSR program. Accordingly, 

sources will be required to perform this 

analysis for the PM2.5 NAAQS and, 

when finalized, PM2.5 increments. Such 

analyses must consider how a source, in 

combination with other sources in the 

area, will impact air quality at existing 

PM2.5 monitor locations, as well as at 

other locations that are appropriate for 

comparing predicted PM2.5

concentrations to the NAAQS based on 

PM2.5 monitor siting requirements and 

recommendations. 

4. How must the PSD preconstruction 

monitoring requirement be 

implemented for PM2.5? 

Sources subject to PSD are subject to 

preconstruction ambient air quality 

monitoring requirements. See sections 

165(a)(7) and 165(e) of the Act and 40 

CFR 51.166(m) and 52.21(m). The PSD 

permitting requirements provide that 

continuous preconstruction ambient air 

quality monitoring must be conducted 

for any criteria pollutant emitted in 

significant amounts. Under 40 CFR 

51.166(i)(5) and 52.21(i)(5), the 

reviewing authority has the discretion to 

exempt an applicant from this 

monitoring requirement if: 

• The maximum modeled 

concentration for the applicable 

averaging period caused by the 

proposed significant emissions increase 

(or net emissions increase) is less than 

the prescribed SMC; or 

• The existing monitored ambient 

concentrations are less than the 

prescribed SMC. 

A source may also use existing data as 

a surrogate for preconstruction 

monitoring if the existing monitored 

data record is determined to be 

representative of the project’s location. 

We proposed five options for how to 

address preconstruction monitoring for 

PM2.5. We are adopting a combination of 

options 1 and 3 from the proposal, 

primarily because we believe that it 

reflects existing procedures for other 

regulated NSR pollutants. The following 

sections summarize the major comments 

received on each option and explain 

why we are not adopting particular 

options. 

Option 1—Require Preconstruction 

Monitoring for All Sources But Exempt 

on a Case-by-Case Basis 

Generally, commenters who 

supported option 1 believed the option 

gives regulatory agencies enough 

flexibility to address sources with 

unique characteristics. One 

commentator stated that another benefit 

is that this option would avoid 

unnecessary installation of new PM2.5

monitors and redundant 

preconstruction monitoring. 

Another commenter, however, 

believed option 1 to be overly 

burdensome until EPA develops an 

SMC. The commenter argued that for 

example, there are many upcoming PSD 

projects in their State, which would be 

located in extremely remote areas where 

there are no local or regional PM2.5

emission sources, so there would be no 

need to collect such data for these areas. 

Additionally, one group of commenters 

stated that option 1 appeared to be 

‘‘streamlining’’ preconstruction permit 

requirements, which is not the intention 

of the Act’s PSD provisions, and that 

EPA does not have the authority to 

exempt sources from the requirements 

of section 165(e)(2). 

We agree with the commenter that 

recommended combining option 3 (the 

use of a 24-hr PM2.5 SMC) with option 

1 and are finalizing this approach. We 

have proposed an SMC for PM2.5 in the 

rulemaking on increments, SILs, and 

SMCs (72 FR 54112, September 21, 

2007). Our regulations at 40 CFR 

51.166(i)(5) and 52.21(i)(5) have allowed 

the use of an SMC as screening tool for 

identifying when an impact is de 

minimis and there is thus little or no 

value in gathering preconstruction 

monitoring data The use of de minimis 

levels of this nature (such as significant 

emission rates and significant impact 

levels) is supported by court precedent 

interpreting the NSR provisions of the 

Act. Alabama Power Co. v. Costle, 636 

F.2d 323, 360 (DC Cir. 1979). (‘‘Unless 

Congress has been extraordinarily rigid, 

there is likely a basis for an implication 

of de minimis authority to provide [an] 

exemption when the burdens of 

regulation yield a gain of trivial or no 

value.’’) 

Option 2—Exempt All Sources From 

Preconstruction Monitoring 

Under option 2, we proposed to 

exempt all PM2.5 sources from 

preconstruction monitoring through a 

blanket determination that the existing 

PM2.5 monitoring network is sufficient. 

One commenter who preferred option 5 

(described subsequently) was also 

supportive of option 2. This commenter 

noted that preconstruction monitoring is 

expensive and can significantly delay a 

project. The commenter also pointed out 

that it is very difficult to locate monitors 

for both direct PM2.5 and precursors 

because precursors may transport over 

long distances before transforming into 

PM2.5. The commenter indicated that we 

should not rely on the existing 

regulations, which are already known to 

be problematic. 

One comment letter from a group of 

environmental advocacy organizations 

specifically opposed option 2. These 


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13These sections actually cross-reference the list 

at 40 CFR 51.166(i)(8)(i) and 52.21(i)(8)(i), however 

we renumbered those paragraphs to paragraph 

(i)(5)(i) of those provisions in the December 31, 

2002 NSR reform rule and inadvertently overlooked 

correcting the cross-references in paragraphs 

(i)(5)(ii) and (i)(5)(iii). See 67 FR 80186. As 

proposed, in this final action we have corrected this 

misnumbering and others in this section. 

commenters noted that spatial gradients 

can be significant for PM2.5, especially 

for direct PM2.5 emissions, and that the 

existing monitoring network is severely 

limited in its spatial coverage, most 

especially in attainment areas where 

PSD preconstruction monitoring 

requirements apply. The commenters 

indicated that to make a blanket 

determination that the existing network 

suffices for any source, regardless of 

where it might choose to locate, would 

be absurd. 

We decided not to finalize option 2 

because we do not believe that the 

current network will be sufficient for all 

existing and potential new sources. As 

stated in the proposal preamble, we 

believe that the existing PM2.5

monitoring record has the following 

limitations: 

• The PM2.5 monitoring data record 

would require spatial interpolation 

between monitors for the determination 

of appropriate concentrations at the 

project’s location. 

• Use of existing monitored data will 

not increase the PM2.5 monitoring data 

record to confirm or contradict 

conventional perceptions. 

• The PM2.5 monitoring data record 

assumes that local hot spots of high 

PM2.5 concentrations do not exist or are 

already being monitored, which may not 

be true in all cases. 

• Automatic acceptance of existing 

measurements does not follow our 

current policy that a case-by-case 

determination needs to be made to 

determine whether preconstruction 

ambient monitoring is necessary. 

• When used with the impact 

modeling, separate concentrations of 

direct and precursor-formed PM are 

needed. 

Option 3—Use SMC’s To Exempt 

Sources From Preconstruction 

Monitoring 

Several commenters supported this 

option adding that this approach 

follows existing procedures to justify 

the exclusion of preconstruction 

monitoring requirements when source 

impacts are less than the SMC or when 

sufficient representative data exists. One 

group of commenters stated that EPA’s 

proposed options 1 and 3, which would 

allow case-by-case or de minimis 

exemptions from the monitoring 

requirements, are ill-conceived as a 

matter of public policy and contradict 

the Act’s PSD provisions. 

We agree with the commenters that 

support adopting option 3 because a 

combination of options 1 and 3 reflects 

existing procedures for other regulated 

NSR pollutants. As discussed 

previously, a de minimis exemption 

from monitoring requirements is 

supported by court precedent 

interpreting the PSD provisions of the 

Act. We do not consider it sound policy 

to require gathering additional data 

when it is unnecessary to demonstrate 

that a proposed source or modification 

will not adversely impact air quality. 

Option 4—Use Existing PM10 Data 

We proposed using the available large 

PM10 data record combined with the 

recently acquired PM2.5 data to provide 

representative ambient measurements 

for most sources. One comment letter 

from an industry group opposed any 

requirement for preconstruction 

monitoring, and endorsed option 4 if 

nationally gathered PM2.5 data is not 

available. Three commenters 

specifically opposed option 4. One 

comment letter from an environmental 

advocacy organization stated that option 

4 is illegal on its face, to the extent that 

EPA intends it as a universally available 

alternative. This comment indicated 

that some individual sources might be 

able to demonstrate that PM10

monitoring could fulfill the statutory 

requirements and purposes of PM2.5

monitoring (e.g., with sufficiently 

protective assumptions about PM2.5/ 

PM10 proportions), but due to the 

variability in the relationship between 

PM2.5 and PM10, EPA cannot 

categorically allow this substitution. 

Two other commenters stated that 

option 4 was not a viable approach due 

to the convoluted nature of attempting 

to infer PM2.5 concentration from PM10

monitoring data for source-specific 

applications. 

We decided not to finalize option 4. 

As we recognized in the proposal 

preamble, the differences in 

characteristics between PM2.5 and PM10

and our limited understanding of their 

relationship are problematic for this 

application. We do not believe that 

generalized factors to convert PM10

concentrations to PM2.5 concentrations 

sufficiently reflect important industryspecific and spatially-related 

characteristics of PM2.5. In addition, 

removing altogether the obligation to 

provide preconstruction PM2.5 ambient 

monitoring data would eliminate 

industry’s contribution to the PM2.5 data 

record when source impacts are more 

than de minimis. 

Option 5—Exempt Sources From 

Preconstruction Monitoring if No SMC 

Is Established 

We noted in the proposed rule that 

the existing regulations at 40 CFR 

51.166(i)(5)(iii) and 52.21(i)(5)(ii) could 

be interpreted to allow a reviewing 

authority to exempt an applicant from 

preconstruction monitoring for any 

pollutant for which we have not 

established an SMC. These provisions 

state that a source may be exempted 

from preconstruction monitoring ‘‘if 

* * * the pollutant is not listed in’’ the 

list of pollutants for which SMC have 

been set.13 The original rationale for this 

exemption is based on the lack of 

adequate methods for measuring 

ambient concentrations of pollutants not 

on the list. See 45 FR 52709, 52723– 

52724. We requested comment on this 

interpretation and any other legal or 

policy rationale that could support 

applying the text of these provisions to 

exempt sources from preconstruction 

monitoring if we elected not to define 

an SMC for PM2.5. 

One commenter stated that option 5 is 

the most practicable to implement until 

an SMC can be established and any 

potential gaps in the monitoring 

network can be filled. Two commenters 

question the legality of option 5 under 

the Act. They added that whatever may 

have been the case when the existing 

list of SMCs was adopted, methods now 

exist for conducting the monitoring 

required under section 165(e)(2). We 

decided not to finalize option 5, and 

have proposed an SMC rule for PM2.5. 

In conclusion, we are finalizing a 

combination of options 1 and 3 from the 

proposal, since we believe that it 

reflects existing procedures for other 

regulated NSR pollutants. Once we 

finalize an SMC for PM2.5, the reviewing 

authority will have the discretion to 

exempt a source from the 

preconstruction monitoring requirement 

if the projected PM2.5 ambient impact of 

the source is below the PM2.5 level 

promulgated in our rules. In addition, 

additional preconstruction monitoring 

data may not be necessary based on the 

availability of existing representative 

monitoring data in the area, as 

discussed previously. 

G. Nonattainment New Source Review 

(NA NSR) Requirements 

To receive a permit for a new major 

source or a major modification, sources 

subject to NA NSR must: 

• Install Lowest Achievable Emission 

Rate (LAER) control technology; 

• Offset new emissions with 

creditable emissions reductions; 


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• Certify that all major sources owned 

or operated by the applicant in the same 

State are in compliance; and 

• Conduct an alternative siting 

analysis demonstrating that the benefits 

of the proposed source significantly 

outweigh the environmental and social 

costs. 

We did not propose, nor are we 

finalizing, any revisions to the first, 

third, and fourth of these requirements. 

Thus, these requirements apply for 

purposes of PM2.5 and its designated 

precursors just as they apply for other 

criteria pollutants and their designated 

precursors. In the remainder of this 

section G, we discuss our final actions 

related to offsets for direct PM2.5

emissions and emissions of PM2.5

precursors. 

1. What is the required offset ratio for 

direct PM2.5 emissions? 

Under section 173 of the Act, all 

major sources and major modifications 

at existing major sources within a 

nonattainment area must obtain 

emissions reductions to offset any 

emissions increases resulting from the 

project in an amount that is at least 

equal to the emissions increase, and that 

is consistent with reasonable further 

progress towards attainment. We refer to 

the proportional difference between the 

amount of the required offsets to the 

amount of emissions increase as the 

‘‘offset ratio.’’ 

The Act specifies an offset ratio for 

several situations. In ozone 

nonattainment areas subject to subpart 2 

(of title I, part D of the Act), the ratio 

is set between 1.1:1 and 1.5:1 depending 

on the area’s level of classification 

pursuant to subpart 2. For other 

nonattainment areas, the Act establishes 

a minimum offset ratio of 1:1 pursuant 

to subpart 1 of title I, part D of the Act. 

As proposed, we are finalizing the 

offset ratio for direct PM2.5 emissions as 

at least 1:1 on a mass basis because the 

PM2.5 program is being implemented 

under subpart 1 of the Act. The 

commenters on this issue generally 

agreed that our regulations should 

require an offset ratio of at least 1:1 

pursuant to subpart 1. 

A few commenters indicated that a 

lower ratio could be acceptable on a 

source-specific basis if accompanied by 

a modeling analysis demonstrating a net 

air quality benefit. One commenter 

suggested that such a demonstration 

would be possible when a direct PM2.5

emissions increase from a tall stack is 

being offset by ground-level PM2.5

emission reductions. Applying diesel 

retrofit technology to bus and truck 

fleets is an example of how ground-level 

PM2.5 emission reductions could be 

achieved. We do not believe that a lower 

offset ratio is authorized under subpart 

1, which prescribes an offset ratio of at 

least 1:1, and therefore we have not 

adopted this approach in our final rules. 

Some of the commenters disagreed 

regarding whether an offset ratio of at 

least 1:1 under subpart 1 represents a 

ceiling or a floor on the level we can 

prescribe in our regulations. We 

interpret section 173 of the Act to allow 

higher offset ratios where necessary to 

achieve reasonable further progress. 

Accordingly, we believe that States may 

establish higher offset ratios in their 

State programs if they wish, but we do 

not believe that it would be appropriate 

for us to do so for PM2.5 in national 

regulations. We do not have cause to 

believe a higher ratio is necessary for 

PM2.5 in each area of the country and 

prefer to leave this to the discretion of 

States. We do not believe that the higher 

offset ratios required for ozone 

precursors under subpart 2 apply in any 

way to direct PM2.5 emissions or PM2.5

precursors. 

2. Which precursors are subject to the 

offset requirement? 

Consistent with our proposal, the 

pollutants that are designated as PM2.5

precursors in a particular area are 

subject to the offset requirement in that 

area. Accordingly, SO2 is subject to 

offsets in all PM2.5 nonattainment areas. 

As a ‘‘presumed-in’’ precursor, NOX will 

be subject to offsets unless a State 

obtains an exemption for its NSR 

program through a demonstration that 

NOX emissions in a particular area are 

not a significant contributor to that 

area’s ambient PM2.5 concentrations. As 

‘‘presumed-out’’ precursors, VOC and 

ammonia would be subject to offsets 

only in areas where the State has 

demonstrated that these emissions are 

significant contributors to the area’s 

ambient PM2.5 concentrations. Two 

commenters on this issue agreed with 

this approach; one commenter 

recommended that we not require 

offsets for any PM2.5 precursors. We 

believe that it is appropriate to offset 

emissions increases of all precursors 

that have been established to contribute 

to the PM2.5 nonattainment problem in 

a particular area. 

3. What is the required offset ratio for 

PM2.5 precursors? 

As discussed previously, the Act 

requires that a source obtain offsets for 

emissions increases that occur in a 

nonattainment area. As with PM2.5

direct emissions, the minimum offset 

ratio permitted under subpart 1 of the 

Act is at least 1:1. Based on these 

requirements of the Act, we are 

finalizing our proposal that an offset 

ratio of at least 1:1 applies where a 

source seeks to offset an increase in 

emissions of a PM2.5 precursor with 

creditable reductions of the same 

precursor. This offset ratio applies for 

all pollutants that have been designated 

as PM2.5 precursors in a particular 

nonattainment area. 

Most commenters agreed with this 

approach. A few commenters indicated 

that an offset ratio of less than 1:1 for 

precursor emissions of PM2.5 should be 

allowed only if there is a net air quality 

benefit and if the lower ratio is justified 

by air quality modeling analysis. They 

noted that for PM2.5 precursors, 

chemical reactivity modeling 

demonstrations should be developed 

and approved that are, at a minimum, 

capable of determining the impacts of 

the precursor emissions on the air 

quality in the nonattainment area in 

which the source is located. As noted 

previously, we do not believe that any 

offset ratio less than 1:1 is permissible 

under subpart 1. 

One commenter stated that consistent 

with the statutory scheme for ozone laid 

out in section 182, and given the 

severity of the health risks associated 

with PM2.5, EPA must require offsets of 

at least 1.15:1 for PM2.5 precursors in 

‘‘moderate’’ nonattainment areas, and 

must increase the offset ratio in 

‘‘serious’’ nonattainment areas or in 

areas that request extensions of their 

attainment deadlines. As mentioned 

previously, we do not believe that 

subpart 2 of the Act (which includes 

section 182) has any relevance to PM2.5

or its precursors. Subpart 2 is specific to 

ozone. In addition, we are implementing 

the PM2.5 program under subpart 1. 

Nevertheless, under the Act, we believe 

that a State may require higher offset 

ratios if it determines that they are 

necessary to achieve reasonable further 

progress. For the reasons discussed 

previously with respect to direct PM2.5, 

we do not believe that it is appropriate 

for us to set higher offset ratios for PM2.5

precursors on a national basis. 

Two commenters requested that we 

make clear in the final rule that an 

increase in precursor emissions need 

only be offset once, even if the increase 

triggers nonattainment NSR under, for 

example, both the ozone and PM2.5

programs. We agree with these 

commenters and are clarifying that a 

precursor emissions increase only needs 

to be offset once. A permit applicant 

will not, for example, need to obtain 

two sets of offsets for NOX emissions if 

NOX is regulated as a precursor both for 

ozone and PM2.5 in the area. The NOX

precursor emissions need only be offset 

once in accordance with the applicable 


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14A full description of this approach is available 

in the technical support document at http://www.

epa.gov/scram001/reports/pmnaaqs_tsd_rsm_all_

021606.pdf and in the docket for this rulemaking, 

Docket ID No. EPA–HQ–OAR–2003–0062. 

15Available in the docket for this rulemaking, 

Docket ID No. EPA–HQ–OAR–2003–0062. 

ratio. To the extent a higher ratio 

applies for ozone under subpart 2, the 

applicant would have to obtain offsets at 

the higher ratio. However, when the 

offset ratios are the same, both 

requirements can be met with a single 

set of NOX offsets. 

4. Is interpollutant trading allowable to 

comply with offset requirements? 

In this final rule, we are allowing 

limited interpollutant trading for 

purposes of offsets only (and not 

netting) under the PM2.5 NA NSR 

program. Specifically, the final rules 

allow interpollutant trading only based 

on a trading ratio established in the SIP 

as part of the attainment demonstration 

approved for a specific nonattainment 

area, on a statewide basis, or in a 

regional, multi-state program. This 

differs from our proposal in that the 

final rules do not allow interpollutant 

trading on a case-by-case basis as part of 

an individual NA NSR permitting 

process. For the purpose of offsets in the 

NA NSR program for PM2.5, the final 

rules allow reductions in direct PM2.5

emissions to offset precursor emissions 

increases, emissions reductions of one 

precursor to offset emissions increases 

of another precursor, and reductions in 

precursor emissions to offset direct 

PM2.5 emissions increases. 

We have completed a technical 

assessment to develop preferred 

interpollutant trading ratios that may be 

used for the purposes of PM2.5 offsets, 

where appropriate. The preferred ratios 

were generated with a PM2.5 response 

surface modeling (RSM) approach based 

on the EPA’s Community Multi-Scale 

Air Quality (CMAQ) model. This RSM 

approach allows one to distinguish the 

impact of direct and precursor 

emissions from particular source 

groupings on total PM2.5 concentrations 

within nine specific urban areas and 

broadly across U.S. regions. This 

approach was recently applied by the 

Agency to inform development of 

potential PM2.5 control strategies as part 

of the Regulatory Impact Assessment 

(RIA) for the final PM2.5 NAAQS.14

Based on results from the RSM, we 

determined the distribution of predicted 

ratios for urban areas and regions across 

the country and developed the preferred 

ratios with a goal to be environmentally 

protective. The technical approach with 

details on data and modeling inputs are 

fully described in a technical memo to 

the docket, ‘‘Details on Technical 

Assessment to Develop Interpollutant 

Trading Ratios for PM2.5 Offsets.’’ 15 Use 

of the preferred ratios is recommended 

by EPA but not mandatory, and we do 

not intend to preclude the opportunity 

for a local demonstration of trading 

ratios on a case-by-case basis and public 

input into that process. 

Our work here and in other recent 

PM2.5 assessments clearly show that the 

relative efficacy of emissions reductions 

varies across pollutants and that a ton 

of direct PM2.5 is generally more 

effective than a ton of precursor 

emissions in reducing overall PM2.5

concentrations. For the purposes of 

reporting information here, we define 

the ‘‘East’’ to be the 37 States either 

completely or in part east of 100 degrees 

west longitude. ‘‘West’’ would include 

the remaining 11 western-most States in 

the continental United States. We found 

the following relationships between 

pollutants in developing the preferred 

trading ratios: 

1. NOX to SO2; SO2 to NOX: Our 

assessment indicated potential disbenefits of 

reducing NOX (i.e., reducing NOX tons in 

urban areas may increase overall PM2.5

concentrations) in the eastern United States 

and urban areas in the western United States. 

Due to the possibility of these disbenefits and 

the high degree of variability in the observed 

NOX to SO2 ratios or SO2 to NOX ratios across 

urban areas, we are not defining preferred 

ratios involving trades between these 

precursors but will rely upon a local 

demonstration to determine the appropriate 

trading ratios. 

2. NOX to Primary PM2.5; Primary PM2.5 to 

NOX: Based on a local demonstration that 

NOX reductions are beneficial in reducing 

PM2.5 concentrations (i.e., no disbenefits from 

NOX reductions as noted previously), our 

assessment indicates that the preferred 

trading ratio is 200 to 1 (NOX tons for PM2.5

tons) or 1 to 200 (PM2.5 tons for NOX tons) 

for areas in the eastern United States, and 

100 to 1 (NOX tons for PM2.5 tons) or 1 to 100 

(PM2.5 tons for NOX tons ) for areas in the 

western United States. 

3. SO2 to Primary PM2.5; Primary PM2.5 to 

SO2: We have determined a nationwide 

preferred ratio of 40 to 1 (SO2 tons for PM2.5

tons) or 1 to 40 (PM2.5 tons for SO2) for trades 

between these pollutants. We recognize there 

is spatial variability here between urban and 

regionally located sources of these pollutants 

that can be addressed through a local 

demonstration to determine an area-specific 

relationship, as appropriate. 

We recommend that States use these 

hierarchies and trading ratios in their 

interpollutant trading programs to 

provide consistency and streamline the 

trading process. As indicated by our 

work and findings, it is appropriate to 

establish acceptable trading ratios for 

interpollutant trading for PM2.5 NSR 

offsets. If States elect to use EPA’s 

recommended trading ratios, they may 

rely on EPA’s technical work and a 

presumption that such ratios will be 

approvable by EPA absent a credible 

showing that EPA’s trading ratios are 

not appropriate for that location. If 

States choose to develop their own 

hierarchies/trading ratios, they will 

have to substantiate by modeling and/or 

other technical demonstrations of the 

net air quality benefit for PM2.5 ambient 

concentrations, and such a trading 

program will have to be approved by 

EPA. 

We acknowledge that the relationship 

between pollutants can vary across 

geographic areas. Thus, local 

demonstrations, to determine trading 

ratios, will need to address a number of 

local factors including, but not limited 

to, the following: 

1. The relative magnitude of emissions of 

direct PM2.5 and precursor gases (e.g., SO2

and NOX) within the geographic area of 

interest. 

2. The relative contribution to local PM2.5

nonattainment of directly emitted PM2.5 and 

individual precursors from the various 

sources or source categories under 

consideration as part of a potential 

interpollutant trade. 

3. The meteorological conditions and 

topography of the area, which result in 

different source-receptor relationships across 

pollutants within the local area. 

We have adopted this approach to 

capture the flexibility advantages of 

interpollutant trading, while remaining 

mindful of the limitations of existing air 

quality models. We believe that the 

regional-scale models used for areawide attainment demonstrations have 

sufficient accuracy to establish an 

overall equivalence ratio for a 

nonattainment area. However, we do not 

believe that available models can 

accurately determine the effects of 

interpollutant trades at a single source. 

In addition, permit-by-permit modeling 

demonstrations are extremely resource 

intensive, only to yield limited results. 

For these reasons, the final rules only 

allow a State to develop its own 

interpollutant trading rule for inclusion 

in its SIP, based on a technical 

demonstration for a specific 

nonattainment area. We will not accept 

case-by-case demonstrations on an 

individual source permit basis. 

The flexibility provided by this policy 

allows sources to select the most costeffective manner to obtain the offsets 

necessary to ensure that PM2.5 air 

quality improves. This will be 

particularly beneficial where offsets for 

one particular pollutant are scarce in a 

particular area, as is often the case for 

direct PM2.5 emissions and SO2. 


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We received a large number of 

comments on this issue representing a 

wide variety of viewpoints. Several 

commenters supported flexible 

interpollutant trading at ratios 

established either on an area-wide basis 

or permit by permit. They often pointed 

out the economic and administrative 

benefits of flexibility in the program, 

especially in areas where offsets for 

some pollutants will be difficult to 

obtain. One commenter asserted that 

such flexibility is essential to the ability 

of enterprises to be able to expand as the 

PM2.5 NAAQS is implemented, 

especially in the program’s early years. 

Another commenter suggested allowing 

such trading on an equal basis, without 

the ‘‘unnecessary complication’’ of 

interpollutant offset ratios. 

Many commenters argued against 

allowing interpollutant trading for 

offsets. These commenters commonly 

pointed out that direct PM2.5 emissions 

typically have a more local impact, 

while the impact of precursor emissions 

are farther afield. A number of 

commenters pointed out the complex 

atmospheric chemistry of secondary 

particulate formation and the 

shortcomings of the air quality models 

currently available to perform a detailed 

PM2.5 formation assessment, specifically 

that local-scale models are not 

sufficiently accurate and regional-scale 

models do not have the resolution to 

show local impacts adequately. 

According to two commenters, trading 

precursors for direct PM2.5 emissions 

raises serious environmental justice 

concerns due to the localized impacts of 

direct PM2.5 emissions. These 

commenters also asserted that the 

equivalence between precursors would 

vary spatially and temporally, making it 

extremely difficult to assess, and that 

PM2.5 precursors also differ in their 

impacts on other air pollution problems, 

such as direct health and welfare 

impacts of SO2 and NOX; and formation 

of ozone, acid deposition, and reactive 

nitrogen deposition. 

We also received comments opposing 

allowing interpollutant trading for 

netting purposes, on the basis that the 

resulting program would be very staffintensive apart from the difficulty of 

demonstrating through modeling the net 

air quality benefit of a single source 

trade. We concur with these 

commenters and are not allowing 

interpollutant trading for netting 

purposes at this time. 

A number of commenters supported 

some types of trades, but not others. 

Most frequently, these commenters 

favored allowing reductions in direct 

PM2.5 emissions to offset precursor 

emissions increases. One commenter 

suggested a hierarchy as follows: Direct 

PM2.5 emissions, SO2, NOX, ammonia, 

and VOC. That is, a pollutant should be 

allowed as an offset for a pollutant 

ranked lower, but not the reverse (e.g., 

reductions in direct PM2.5 emissions 

could be used to offset increases in any 

of the listed pollutants, SO2 emissions 

reductions could offset NOX increases, 

etc.). 

As previously noted, this rule allows 

interpollutant and interprecursor 

trading of offsets according to a SIPapproved trading program. To be 

approved, the trading program must 

either adopt EPA’s recommended 

trading ratios or be backed up by 

regional-scale modeling that 

demonstrates a net air quality benefit 

using appropriate overall offset ratios 

for such trades for a specified 

nonattainment area, State, or multi-State 

region. There is considerable 

uncertainty about the relationship of 

precursor and direct PM2.5 emissions to 

localized ambient PM2.5 concentration 

both spatially and temporally. Given the 

uncertainty as to localized adverse and 

beneficial effects, we have opted for 

program flexibility. We believe this is 

necessary, in part, because of the 

shortage of available offsets for some 

pollutants, particularly direct PM2.5

emissions and SO2, in many areas. 

H. How will the transition to the PM2.5

PSD requirements occur? 

1. Background 

On October 23, 1997, after the 

NAAQS for PM2.5 was originally 

promulgated, we issued a guidance 

document entitled ‘‘Interim 

Implementation for the New Source 

Review Requirements for PM2.5,’’ John 

S. Seitz, EPA. As noted in that guidance, 

section 165 of the Act suggests that PSD 

requirements become effective for a new 

NAAQS upon the effective date of the 

NAAQS. Section 165(a)(1) of the Act 

provides that no new or modified major 

source may be constructed without a 

PSD permit that meets all of the section 

165(a) requirements with respect to the 

regulated pollutant. Moreover, section 

165(a)(3) provides that the emissions 

from any such source may not cause or 

contribute to a violation of any NAAQS. 

Also, section 165(a)(4) requires BACT 

for each pollutant subject to PSD 

regulation. 

The 1997 guidance stated that sources 

should continue to use implementation 

of a PM10 program as a surrogate for 

meeting PM2.5 NSR requirements until 

certain difficulties were resolved, 

primarily the lack of necessary tools to 

calculate the emissions of PM2.5 and 

related precursors, the lack of adequate 

modeling techniques to project ambient 

impacts, and the lack of PM2.5

monitoring sites. With this final action 

and technical developments in the 

interim, these difficulties have largely 

been resolved. 

2. Transition for ‘‘Delegated States’’ 

The Federal PSD program is 

contained in 40 CFR 52.21. This section 

is the Federal implementation plan for 

areas lacking an approved PSD program. 

We implement this program in Indian 

country and some U.S. territories, but 

for the most part we have delegated 

implementation of 40 CFR 52.21 to 

those States without approved PSD 

programs (typically referred to as 

‘‘delegated States’’). Except as provided 

in the grandfathering provisions that 

follow, these final rules go into effect 

and must be implemented beginning on 

the effective date of this rule, July 15, 

2008 in all areas subject to 40 CFR 

52.21, including the delegated States. 

Consistent with 40 CFR 52.21(i)(1)(x), 

wherein EPA grandfathered sources or 

modifications with pending permit 

applications based on PM from the PM10

requirements established in 1987, EPA 

will allow sources or modifications who 

previously submitted applications in 

accordance with the PM10 surrogate 

policy to remain subject to that policy 

for purposes of permitting if EPA or its 

delegate reviewing authority 

subsequently determines the application 

was complete as submitted. This is 

contingent upon the completed permit 

application being consistent with the 

requirements pursuant to the EPA 

memorandum entitled ‘‘Interim 

Implementation of New Source Review 

Requirements for PM2.5’’ (Oct. 23, 1997) 

recommending the use of PM10 as a 

surrogate for PM2.5. Accordingly, we 

have added 40 CFR 52.21(i)(1)(xi) to 

reflect this grandfathering provision. 

3. Transition for ‘‘SIP-Approved States’’ 

The requirements for State PSD 

programs are contained in 40 CFR 

51.166. Most States have developed PSD 

programs according to these 

requirements, which we have approved 

into each State’s implementation plan. 

States with PSD programs approved 

under 40 CFR 51.166 are called ‘‘SIPapproved States.’’ 

States with SIP-approved PSD 

programs that require amendments to 

incorporate these final NSR rule 

changes for PM2.5 will need time to 

accomplish these SIP amendments. For 

example, a State may need to amend its 

existing regulations to add the specific 

significant emissions rate for PM2.5 or a 

designated precursor. In our December 

31, 2002 Federal Register notice 


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16 In our proposal, we proposed April 5, 2008 as 

a deadline for States to comply with the revised 

nonattainment NSR and PSD requirements in this 

rule. However, in light of the time it has taken to 

complete this final rule, expecting States to submit 

required SIP revisions consistent with this final rule 

by April 5, 2008 is no longer practical or fair. 

Nevertheless, States are still currently required to 

implement a PSD program for PM2.5, and we still 

expect States to fulfill the SIP infrastructure 

requirements of CAA section 110(a)(2), including 

the PSD program requirements, by April 5, 2008. 

We believe these PSD program requirements are 

currently met by implementing the transitional PSD 

program for PM2.5 described in this preamble (a.k.a. 

the PM10 surrogate policy). In accordance with a 

Consent Decree in Environmental Defense and 

American Lung Ass’n v. Johnson, No. 1:05CV00493 

(D.D.C. June 15, 2005), EPA must determine by 

October 5, 2008 whether each State has submitted 

the SIP revisions for the PM2.5 PSD program 

required under section 110(a)(2) of the Act. This 

rulemaking does not change the specific guidance 

we previously provided to States on what they 

should submit by April 5, 2008 to comply with 

section 110(a)(2). 

promulgating other changes to the NSR 

program, we explained that the Act does 

not specifically address the timeframe 

by which States must submit SIP 

revisions when we revise the PSD and 

NA NSR rules. We nonetheless looked 

to section 110(a)(1) to guide our 

decision to require States to adopt and 

submit plan revisions within 3 years 

from when we publish changes in the 

Federal Register. We codified this 

approach in the PSD regulations at 40 

CFR 51.166(a)(6)(i) and applied this 

same timeframe to State NA NSR 

programs through that final rule action. 

64 FR 80241. This rule follows our 

established approach for determining 

when States must adopt and submit 

revised SIPs following changes to the 

NSR regulations, but does not revise 

otherwise applicable SIP submittal 

deadlines. Accordingly, we are 

requiring States with SIP-approved PSD 

programs to submit revised PSD 

programs and revised NA NSR programs 

for PM2.5 (see section V.I.) within 3 

years from the date of this action.16

During this SIP development period, 

the PM2.5 NAAQS must still be 

protected under the PSD program in 

such States. We are finalizing our 

proposed option 1 that if a SIP-approved 

State is unable to implement a PSD 

program for the PM2.5 NAAQS based on 

these final rules, the State may continue 

to implement a PM10 program as a 

surrogate to meet the PSD program 

requirements for PM2.5 pursuant to the 

1997 guidance mentioned previously. 

Under option 1 for SIP-approved States, 

we had proposed two additional 

requirements. These were to require 

sources to demonstrate that emissions 

from construction or operation of the 

facility will not cause or contribute to a 

violation of the PM2.5 NAAQS and to 

include condensable PM emissions in 

determining major NSR applicability 

and control requirements. We are not 

finalizing either of these additional 

requirements of our proposed option 1. 

We have dropped the requirement for 

demonstrating compliance with the 

PM2.5 NAAQS in order to maintain 

consistency in the application of the 

existing surrogate policy across the PSD 

program during the interim period. 

Since in the final rule we are otherwise 

allowing SIP-approved States to 

continue with the existing PM10

surrogate policy to meet the PSD 

requirements for PM2.5, partially 

implementing the PM10 surrogate policy 

in this manner would be confusing and 

difficult to administer. Thus, to ensure 

consistent administration during the 

transition period, we have elected to 

maintain our existing PM10 surrogate 

policy which only recommends as an 

interim measure that sources and 

reviewing authorities conduct the 

modeling necessary to show that PM10

emissions will not cause a violation of 

the PM10 NAAQS as a surrogate for 

demonstrating compliance with the 

PM2.5 NAAQS. Also as discussed 

previously in section V.E, we are not 

requiring condensable emissions to be 

fully integrated into the PM2.5 program 

until the end of the transition period to 

validate test methods discussed in 

section V.E of this preamble. 

In our proposal, we offered two 

additional options for the SIP 

development period in States with SIPapproved PSD programs. Under option 

2, we would have updated the 1997 

guidance to reflect the provisions in 

these final rules and allowed States to 

run a PM2.5 program pursuant to this 

updated guidance. Alternatively under 

option 2, we would have amended 

appendix S and 40 CFR 52.24 so that the 

PSD requirements of 40 CFR 52.21 

would govern the issuance of major NSR 

permits during the SIP development 

period. Finally, under option 3, we 

would have allowed a State to request 

delegation of just the Federal PM2.5 PSD 

program in 40 CFR 52.21 in that State. 

A State that otherwise had a SIPapproved PSD program could have 

requested delegation for PM2.5 by 

informing us that it did not intend to 

submit a PSD SIP for PM2.5 in the 

immediate future. 

We received several comments 

supporting option 1, although some of 

these commenters requested that we not 

require condensable emissions to be 

included until the concerns with test 

methods were resolved. One of these 

commenters favored continuing to 

implement the PM10 program as a 

surrogate under the 1997 guidance to 

provide clarity and certainty to the 

permitting agency and regulated 

community. The commenter indicated 

that PM2.5 inventories and methods for 

estimating emission rates are 

rudimentary and may even be 

nonexistent in some cases, which would 

make permitting onerous. 

A few commenters opposed option 1. 

One of these commenters indicated that 

we should not continue outdated policy 

(i.e., the 1997 NSR guidance) because it 

does not address the PM2.5 problem, 

cannot be implemented in some States, 

and does not incorporate precursor 

emissions. 

Four commenters expressed support 

for option 2. Three of these suggested 

that we issue updated guidance to 

incorporate these PSD requirements for 

PM2.5, while one preferred that we 

revise appendix S to point to the 

requirements of 40 CFR 52.21. We 

received one comment in favor of option 

3 and three opposed. 

Two commenters supported 

approaches different from our options. 

One of these commenters requested that 

the interim framework should, at a 

minimum, ensure that any new or 

modified project that exceeds thresholds 

use BACT. The commenter also 

suggested that we require offsets for 

projects approved before the other 

protective elements of the full PSD 

program are in place to ensure that there 

is no significant deterioration in air 

quality. Another commenter stated that 

none of the proposed options were 

viable for their State. The commenter 

requested that we allow States to 

continue their existing PM10 program as 

a surrogate for PM2.5, without caveat. 

As noted previously, we are finalizing 

proposed option 1, without the 

requirement of demonstrating 

compliance with the PM2.5 NAAQS or 

the requirement to include condensable 

emissions. We believe that our final rule 

is reasonable for the following reasons. 

First, PM10 will act as an adequate 

surrogate for PM2.5 in most respects, 

because all new major sources and 

major modifications that would trigger 

PSD requirements for PM2.5 would also 

trigger PM10 requirements because PM2.5

is a subset of PM10. Second, both of the 

precursors designated in the final rule— 

SO2 and NOX (presumptively)—are 

already regulated under State NSR 

programs for other criteria pollutants. 

Thus, those precursors will be subject to 

NSR through those other programs. We 

do not believe that the other options or 

suggestions offer significant advantages 

that outweigh the utility and ease of 

implementation of this approach. 

States may include grandfathering 

provisions similar to the ones EPA 


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17As discussed earlier, we are following the 

precedent we established in our 2002 rule for NA 

NSR program revisions to allow States adequate 

time to adopt these revisions. For practical and 

fairness reasons, we are not requiring the NA NSR 

elements of this rule to be submitted by April 5, 

2008, as we had proposed. However, the States are 

still required to submit nonattainment plans for 

PM2.5 (including NA NSR programs) on April 5, 

2008. We believe this requirement is satisfied by 

implementing the transitional NA NSR program for 

PM2.5 (a.k.a. the PM10 surrogate policy) described in 

our April 5, 2005 guidance, or, if submitted after 

the effective date of this rule, implementing 

Appendix S as revised in this rule. This rulemaking 

does not change the specific guidance we 

previously provided to States on what they should 

submit to EPA by April 5, 2008 to comply with 

nonattainment area requirements under Part D. 

included in the transition requirements 

for 40 CFR 52.21. 

I. How will the transition to the PM2.5

NA NSR requirements occur? 

1. Background 

The requirements for State NA NSR 

programs are contained in 40 CFR 

51.165. All States with nonattainment 

areas have developed NA NSR programs 

according to these requirements, which 

we have approved into each State’s 

implementation plan. However, as 

noted previously, it takes time for a 

State to amend its SIP when it must 

make changes to its NA NSR program. 

According to the provisions of 40 CFR 

52.24(k), during such an interim period 

when a State lacks an approved NA NSR 

program for a particular pollutant, 

appendix S of 40 CFR part 51 applies for 

NA NSR permitting. 

Section 172(c)(5) of the Act requires 

that States issue major NSR permits for 

construction and major modifications of 

major stationary sources in any 

nonattainment area. Thus, since the 

PM2.5 nonattainment designations 

became effective on April 5, 2005, States 

are now required to issue major NSR 

permits that address the section 173 NA 

NSR requirements for PM2.5. 

On the date that the PM2.5

nonattainment designations took effect 

(April 5, 2005), we issued guidance to 

address implementation of the NA NSR 

program pending the completion of this 

action to develop implementation rules 

for PM2.5. See memorandum from 

Stephen D. Page, Director, Office of Air 

Quality Planning and Standards to 

Regional Air Directors, ‘‘Implementation 

of New Source Review Requirements in 

PM2.5 Nonattainment Areas’’ (April 5, 

2005). 

Our current guidance permits States 

to implement a PM10 NA NSR program 

as a surrogate to address the 

requirements of NA NSR for the PM2.5

NAAQS. A State’s surrogate major NSR 

program in PM2.5 nonattainment areas 

may consist of either the 

implementation of the State’s SIPapproved NA NSR program for PM10 or 

implementation of a major NSR program 

for PM10 under the authority in 40 CFR 

part 51, appendix S. 

2. Transition 

With this finalization of the new 

PM2.5 NSR implementation 

requirements under 40 CFR 51.165, 

States now have the necessary tools to 

implement a NA NSR program for PM2.5. 

After the effective date of the amended 

rule (that is, July 15, 2008, States will 

no longer be permitted to implement a 

NA NSR program for PM10 as a surrogate 

for the PM2.5 NA NSR requirements. 

Most States will then need to implement 

a transitional PM2.5 NA NSR program 

under appendix S (as amended in this 

rulemaking action) until EPA approves 

changes to a State’s SIP-approved NA 

NSR program to reflect the new 

requirements under 40 CFR 51.165. At 

this time, we do not believe it is 

appropriate to allow grandfathering of 

pending permits being reviewed under 

the PM10 surrogate program in 

nonattainment areas, mainly because of 

a State’s obligations to expedite 

attainment and the fact that we had not 

established a similar precedent for 

transitioning from PM to PM10. 

The NA NSR provisions in a State’s 

existing SIP-approved NA NSR program 

would also apply in areas designated as 

nonattainment for the PM2.5 NAAQS if 

the SIP-approved regulations contain a 

generic requirement to issue part D 

permits in areas designated as 

nonattainment for any criteria pollutant 

and do not otherwise need to be 

amended to incorporate the changes 

finalized in this action. States belonging 

to the following categories will need to 

revise their NA NSR regulations and 

submit them to EPA for incorporation 

into the SIP within 3 years from the date 

of this action 17: 

• States that have nonattainment 

regulations which need to be amended 

to incorporate the new PM2.5

requirements. 

• States that have designated 

nonattainment areas for PM2.5 and their 

nonattainment NSR regulations 

specifically list the areas in which NA 

NSR applies (i.e., the list does not 

include the designated nonattainment 

areas for PM2.5). 

• States that have not previously had 

nonattainment areas but now have 

nonattainment areas for PM2.5. 

These States will have to implement 

a transitional NA NSR permitting 

program for PM2.5 pursuant to 40 CFR 

52.24(k) and appendix S until their 

existing part D SIPs are revised to meet 

these new PM2.5 NSR requirements 

under 40 CFR 51.165. 

3. Implementation of NSR Under the 

‘‘Emissions Offset Interpretative Ruling’’ 

(40 CFR Part 51, Appendix S) With 

Revisions 

In general, appendix S requires new 

or modified major sources to meet LAER 

and obtain sufficient offsetting 

emissions reductions to assure that a 

new major source or major modification 

of an existing major source will not 

interfere with the area’s progress toward 

attainment. Readers should refer to 

appendix S for a complete 

understanding of these and other 

appendix S requirements. In this action, 

we are finalizing our proposed revisions 

to appendix S to include provisions 

necessary to implement a transitional 

NA NSR program for PM2.5, including 

significant emissions rates applicable to 

major modifications for PM2.5 and, as 

appropriate, precursors. Additionally, 

since we are finalizing interpollutant 

trading provisions in the NSR rules at 

40 CFR 51.165, we are also amending 

appendix S to allow interpollutant 

trading for PM2.5. Appendix S applies 

directly to new and modified major 

stationary sources. In accordance with 

the requirements of section 110(a)(2)(c) 

of the Act, we believe that the majority 

of States have the legal authority to 

issue permits consistent with these 

requirements under an existing SIPapproved permitting program. 

Nonetheless, at least one State has 

reported that it lacks the legal authority 

to issue permits implementing the 

requirements of appendix S under its 

existing permitting rules. 

If a State is unable to apply the 

requirements of appendix S, we will act 

as the reviewing authority for the 

relevant portion of the permit. We 

believe that it is appropriate for EPA to 

issue the preconstruction permits in 

such circumstances. Congress amended 

the Act in 1990 to remove the 

requirements that would have applied a 

construction ban in areas that lacked a 

SIP-approved part D permit program. 

Thus, we believe that it is consistent 

with Congressional intent that either the 

State or EPA issues construction permits 

for those projects meeting the applicable 

criteria during the interim period. See 

the preamble of the proposal for this 

rule for more detail on the legal basis for 

requiring States to issue NA NSR 

permits pursuant to appendix S during 

the SIP development period (70 FR 

66045–46). 

We received three comments 

supporting the issuance of NA NSR 

permits under appendix S during the 

SIP development period. Two of these 


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commenters expected States generally to 

be able to do so, while one suggested 

that EPA issue such permits because 

States will lack the authority to do so 

without protracted rule revisions. One 

of these commenters also suggested that 

we revise appendix S to authorize 

interprecursor trading during the 

transition period, believing that the 

paucity of existing direct PM2.5

emissions and SO2 offsets likely will 

make business expansion in PM2.5

nonattainment areas from now until at 

least April 2008 impossible unless this 

is done. One commenter suggested that 

we suspend the 2005 PM2.5 NSR 

guidance which allows use of PM10

emissions as a surrogate for PM2.5

emissions in PM2.5 nonattainment areas 

when we adopt the final PM2.5

implementation rules, while three other 

commenters requested continued 

implementation of that guidance during 

the interim period. 

As noted previously, this final action 

will require States to amend their NA 

NSR programs consistent with the 

amended rules at 40 CFR 51.165. During 

the SIP development period, where they 

have legal authority to do so, States 

must issue NA NSR permits under 

appendix S (as revised for purposes of 

the PM2.5 program). To address one of 

the points raised by commenters, we are 

amending appendix S to allow 

interpollutant trading for PM2.5 in this 

final rule. Where a State determines that 

it does not have legal authority to issue 

such permits, we will act as the 

reviewing authority. As of the effective 

date of this action, the 2005 PM2.5 NSR 

guidance on use of PM10 emissions as a 

surrogate for PM2.5 emissions will 

remain in effect only for PSD in the SIPapproved States during the SIP 

development period. In the delegated 

PSD States and in nonattainment areas, 

the new PM2.5 requirements will apply 

immediately on the effective date of this 

final action. 

J. Does major NSR apply to PM2.5

precursors during the SIP development 

period? 

As discussed previously in section 

V.A, we have taken final action on NSR 

applicability for PM2.5 precursors. 

Specifically, we have designated SO2 as 

a national precursor to PM2.5 in all 

areas, NOX as a ‘‘presumed-in’’ 

precursor in all areas, VOC as a 

‘‘presumed-out’’ precursor in all areas, 

and ammonia as a ‘‘presumed-out’’ 

precursor. Thus, States have the option 

of excluding NOX as a precursor by 

demonstrating that NOX emissions are 

not a significant contributor to ambient 

PM2.5 concentrations in a particular 

area. In addition, States have the option 

of identifying VOC and/or ammonia as 

precursor(s) by demonstrating that 

emissions of VOC and/or ammonia are 

a significant contributor in an area, and 

thus should be subject to major NSR. 

In the proposal, during the SIP 

development period, we proposed that 

SO2 should be treated as a regulated 

PM2.5 precursor as of the effective date 

of this final rule since there is no doubt 

about its status as such in any area and 

proposed to defer NSR applicability for 

NOX until a State SIP submittal so that 

if a State elected to submit information 

to rebut the presumption that NOX is a 

regulated PM2.5 precursor, the State 

would have an opportunity to do so in 

its SIP submittal. We also proposed that 

VOCs and ammonia would not be 

treated as PM2.5 precursors during the 

interim period because they are 

presumed not to be precursors until 

they have been demonstrated to be 

through a State’s SIP submittal. 

A few commenters supported staying 

the applicability of NSR to all 

precursors during the interim period. 

However, two of these supporters 

suggested that EPA establish 

mechanisms for interpollutant trading 

for offsets during the interim period so 

that increases in direct PM2.5 emissions 

can be offset with SO2 or NOX emissions 

reductions. Another supporter noted 

that their State cannot impose 

obligations on NSR applicants until 

those obligations are established in State 

regulations or statutes. Another 

indicated that this delay would allow 

States the time to develop experience 

and knowledge in establishing local 

photochemical models and to 

performance test their accuracy. 

Two commenters opposed staying 

NSR applicability for any precursors. 

They believe that this would make 

attainment more difficult. One 

commenter suggested that SO2 should 

be designated as a precursor during the 

interim period, and another suggested 

the same for SO2 and NOX. 

Based on the comments, we have been 

persuaded that SIP-approved PSD States 

will not have the authority to regulate 

PM2.5 precursors before they have 

amended their SIPs to incorporate these 

requirements in attainment areas. Thus, 

in order to allow time for these States 

to revise their regulations to incorporate 

such requirements, this final action does 

not require regulation of SO2 or NOX as 

precursors to PM2.5 under PSD until the 

SIP development period ends. In 

addition, we are allowing SIP-approved 

PSD States to continue with the existing 

PM10 surrogate policy to meet the PSD 

requirements for PM2.5. However, for 

delegated PSD States, SO2 and NOX are 

regulated as precursors from the 

effective date of this rule. However, 

these States or EPA have the option of 

excluding NOX as a precursor by 

demonstrating that NOX emissions are 

not a significant contributor to ambient 

PM2.5 concentrations in a particular 

area. 

For nonattainment areas, the 

transitional program pursuant to 

appendix S will apply on the effective 

date of this action. Under appendix S, 

SO2 will be regulated as a precursor in 

all nonattainment areas for PM2.5. 

However, unlike in the proposal, NOX

will not be regulated as a precursor for 

PM2.5 because we believe it is 

appropriate to give States the 

opportunity to determine whether NOX

emissions are a significant contributor 

to the ambient PM2.5 problem, and to 

make the appropriate demonstration in 

their SIP. Finally, for States determining 

that VOC and/or ammonia are PM2.5

precursors under their SIPs, we will 

approve their definition of ‘‘significant 

emissions rate’’ for each precursor based 

on an appropriate demonstration. 

K. Are there any Tribal concerns? 

Some Tribal areas may be designated 

as nonattainment, in part because of 

pollution that is transported from 

surrounding State lands. Tribal 

representatives have advocated for 

additional flexibility to address 

nonattainment problems caused by 

transported pollution, such as a pool of 

available NSR offset set-asides (which 

we expect would come from State offset 

pools or banks), because they have 

limited ability to generate offsets on 

their own. Tribal representatives have 

raised these and other concerns in 

discussions on implementation of the 8- 

hour ozone and PM2.5 standards, and in 

comments on the 8-hour ozone 

implementation rule. We requested 

comment on whether emissions offset 

set-asides, possibly generated by 

innovative measures to promote 

additional emissions reductions, are an 

appropriate method to help level the 

playing field for the Tribes and support 

economic development in Tribal areas. 

We also requested comment on ways in 

which States may help provide the 

Tribes access to offsets from non-Tribal 

areas. We received no comments on 

these issues. 

We recently proposed Tribal NSR 

rules. See 71 FR 48696, August 21, 

2006. They include a NA NSR rule, 

which refers to appendix S for its 

substantive requirements, and a minor 

NSR rule. In recognition of the concerns 

mentioned above, we have proposed 

and sought comments on options for 

obtaining offset relief in that proposal. 


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We will address these issues in the 

context of that rule. 

L. What are the requirements for minor 

NSR for PM2.5? 

Pursuant to section 110(a)(2)(C) of the 

Act, States must have a minor source 

permitting program. This applies to new 

and modified stationary sources that are 

not considered major for a criteria 

pollutant or a precursor for a criteria 

pollutant. Prior to this action, States 

were required to include the following 

pollutants in their minor NSR program: 

• VOC, 

• SO2, 

• NOX, 

• CO, 

• PM10, and 

• Lead (Pb). 

Based on this action, States must now 

amend their minor source programs to 

include direct PM2.5 emissions and 

precursor emissions in the same manner 

as included for purposes of PM2.5 major 

NSR. 

M. Rural Transport Areas 

In the proposal for the Clean Air Fine 

Particle Implementation Rule and this 

NSR implementation rule for PM2.5, we 

considered the option of classifying 

some nonattainment areas as transport 

areas that suffer from overwhelming 

transport, and of developing NA NSR 

rules specific to such areas. However, 

the final implementation rule does not 

include the rural transport 

classification. Consequently, no NA 

NSR rules have been developed or 

finalized in this rule. 

VI. Statutory and Executive Order 

Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review 

Under Executive Order (EO) 12866 

(58 FR 51735, October 4, 1993), this 

action is a ‘‘significant regulatory 

action’’ because it is likely to raise novel 

legal or policy issues arising out of legal 

mandates, the President’s priorities, or 

the principles set forth in the Executive 

Order. Accordingly, EPA submitted this 

action to the Office of Management and 

Budget (OMB) for review under EO 

12866 and any changes made in 

response to OMB recommendations 

have been documented in the docket for 

this action. 

B. Paperwork Reduction Act 

The information collection 

requirements in this rule have been 

submitted for approval to the OMB 

under the Paperwork Reduction Act, 44 

U.S.C. 3501 et seq. The information 

collection requirements are not 

enforceable until OMB approves them. 

The Information Collection Request 

(ICR) document prepared by EPA has 

been assigned OMB Control Number 

2060–0003 (EPA ICR No. 1230.21). 

To achieve the purposes of the major 

NSR program, certain records and 

reports are necessary for the State or 

local agency (or the EPA Administrator 

in non-delegated States), for example, 

to: (1) Confirm the compliance of status 

of stationary sources, identify any 

stationary sources not subject to the 

rules, and identify stationary sources 

subject to the rules; and (2) ensure that 

the stationary source control 

requirements are being achieved. The 

information would be used by EPA or 

State enforcement personnel to (1) 

identify stationary sources subject to the 

rules, (2) ensure that appropriate control 

technology is being properly applied, 

and (3) ensure that the emission control 

devices are being properly operated and 

maintained on a continuous basis. 

This final NSR rule does not create 

new information collection 

requirements, but rather expands the 

coverage of the existing requirements of 

the major NSR program. Specifically, 

the rule changes finalized in this action 

add PM2.5 to the list of air pollutants 

that must be addressed in the major 

NSR program, and the companion 

proposal adds certain elements that are 

necessary for a complete PM2.5 NSR 

program. This change is unlikely to 

increase significantly the number of 

NSR permits that must be issued, but 

may add to the analyses that sources 

and Federal, State, and local reviewing 

authorities must conduct as part of the 

construction permit application and 

review process. 

We expect the rule changes finalized 

in this action to increase the burden 

associated with major NSR permitting 

for tracking new emissions of PM2.5

against increments; collecting ambient 

air quality monitoring data for existing 

PM2.5 concentrations; reviewing the 

effects of PM2.5 emissions on soils and 

vegetation, as well as on air quality 

related values in Class I areas; 

determining the appropriate best 

available control technology or lowest 

achievable emission rate; and/or 

obtaining offsets. At the same time, 

there would be a reduction in burden 

directly associated with the revocation 

of the annual increment for PM10, which 

is proposed in the proposed rule. 

Over the 3-year period covered by the 

ICR, we estimate an average annual 

burden increase of about 39,000 hours 

(about 8 percent) and $4.3 million 

(about 10 percent) for all industry 

entities that would be affected by this 

final NSR rule. For the same reasons, we 

also expect the final rule to increase 

burden for the State and local 

authorities reviewing permit 

applications when fully implemented. 

In addition, there would be additional 

burden for State and local agencies to 

revise their SIPs to incorporate the 

proposed changes. We estimate the 

combined increase in burden to average 

about 16,000 hours and $700,000 

annually for all State and local 

reviewing authorities, which is less than 

13 percent. 

Burden means the total time, effort, or 

financial resources expended by persons 

to generate, maintain, retain, or disclose 

or provide information to or for a 

Federal agency. This includes the time 

needed to review instructions; develop, 

acquire, install, and utilize technology 

and systems for the purposes of 

collecting, validating, and verifying 

information, processing and 

maintaining information, and disclosing 

and providing information; adjust the 

existing ways to comply with any 

previously applicable instructions and 

requirements; train personnel to be able 

to respond to a collection of 

information; search data sources; 

complete and review the collection of 

information; and transmit or otherwise 

disclose the information. 

An agency may not conduct or 

sponsor, and a person is not required to 

respond to a collection of information 

unless it displays a currently valid OMB 

control number. The OMB control 

numbers for EPA’s regulations in 40 

CFR are listed in 40 CFR part 9. When 

this ICR is approved by OMB, the 

Agency will publish a technical 

amendment to 40 CFR part 9 in the 

Federal Register to display the OMB 

control number for the approved 

information collection requirements 

contained in this final rule. 

C. Regulatory Flexibility Act 

The Regulatory Flexibility Act (RFA) 

generally requires an agency to prepare 

a regulatory flexibility analysis of any 

rule subject to notice and comment 

rulemaking requirements under the 

Administrative Procedure Act or any 

other statute unless the Agency certifies 

that the rule will not have a significant 

economic impact on a substantial 

number of small entities. Small entities 

include small businesses, small 

organizations, and small governmental 

jurisdictions. 

For purposes of assessing the impacts 

of this proposed rule on small entities, 

‘‘small entity’’ is defined as: (1) A small 

business as defined by the Small 

Business Administration’s regulations at 

13 CFR 121.201; (2) a small 

governmental jurisdiction that is a 

government or a city, county, town, 


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school district or special district with a 

population of less than 50,000; and (3) 

a small organization that is any not-forprofit enterprise which is independently 

owned and operated and is not 

dominant in its field. 

After considering the economic 

impacts of this final rule on small 

entities, I certify that this rule will not 

have a significant economic impact on 

a substantial number of small entities. 

The requirements of this final rule apply 

only to new major stationary sources or 

major modifications of existing major 

stationary sources. This final rule does 

not create any new requirements under 

the major NSR program, but simply 

expands the program to cover an 

additional pollutant, referred to as 

PM2.5. There is no reason to expect that 

the rule will significantly or uniquely 

affect small businesses, organizations, or 

governments (few, if any, of which act 

as reviewing authorities pursuant to this 

final rule). 

D. Unfunded Mandates Reform Act 

Title II of the Unfunded Mandates 

Reform Act of 1995 (UMRA), Public 

Law 104–4, establishes requirements for 

Federal agencies to assess the effects of 

their regulatory actions on State, local, 

and tribal governments and the private 

sector. Under section 202 of the UMRA, 

we generally must prepare a written 

statement, including a cost-benefit 

analysis, for proposed and final rules 

with ‘‘Federal mandates’’ that may 

result in expenditures to State, local, 

and tribal governments, in aggregate, or 

to the private sector, of $100 million or 

more in any 1 year. Before promulgating 

an EPA rule for which a written 

statement is needed, section 205 of the 

UMRA generally requires us to identify 

and consider a reasonable number of 

regulatory alternatives and adopt the 

least costly, most cost-effective, or least 

burdensome alternative that achieves 

the objectives of the rule. The 

provisions of section 205 do not apply 

when they are inconsistent with 

applicable law. Moreover, section 205 

allows us to adopt an alternative other 

than the least-costly, most cost-effective, 

or least-burdensome alternative if the 

Administrator publishes with the final 

rule an explanation of why that 

alternative was not adopted. Before we 

establish any regulatory requirements 

that may significantly or uniquely affect 

small governments, including tribal 

governments, we must have developed 

under section 203 of the UMRA a small 

government agency plan. The plan must 

provide for notifying potentially 

affected small governments, enabling 

officials of affected small governments 

to have meaningful and timely input in 

the development of our regulatory 

proposals with significant Federal 

intergovernmental mandates, and 

informing, educating, and advising 

small governments on compliance with 

the regulatory requirements. 

We have determined that this rule 

does not contain a Federal mandate that 

may result in expenditures of $100 

million or more for State, local, and 

tribal governments, in the aggregate, or 

the private sector in any 1 year. The 

final rule does not add any new 

requirements to the NSR program; it 

simply expands the program to cover 

PM2.5 in addition to the several other 

pollutants already defined as regulated 

NSR pollutants. (Technically, the rule 

also subjects the precursors to PM2.5 to 

the NSR program. However, these 

precursors (SO2, NOX, and VOC) are 

already subject to the existing NSR 

program.) As discussed previously in 

section VI.B on the Paperwork 

Reduction Act, the expansion of the 

NSR program to cover PM2.5 will only 

marginally increase the expenditures of 

State, local, and tribal governments and 

the private sector on the program. Thus, 

this action is not subject to the 

requirements of sections 202 and 205 of 

the UMRA. 

The EPA has determined that this rule 

contains no regulatory requirements that 

might significantly or uniquely affect 

small governments. As noted 

previously, this rule does not create any 

new requirements under the major NSR 

program, but simply expands the 

program to cover an additional pollutant 

(PM2.5). There is no reason to expect that 

the rule will significantly or uniquely 

affect small governments, few if any of 

which act as reviewing authorities. 

E. Executive Order 13132—Federalism 

Executive Order 13132, entitled 

‘‘Federalism’’ (64 FR 43255, August 10, 

1999), requires us to develop an 

accountable process to ensure 

‘‘meaningful and timely input by State 

and local officials in the development of 

regulatory policies that have federalism 

implications.’’ ‘‘Policies that have 

federalism implications’’ is defined in 

the Executive Order to include 

regulations that have ‘‘substantial direct 

effects on the States, on the relationship 

between the national government and 

the States, or on the distribution of 

power and responsibilities among the 

various levels of government.’’ 

This final rule does not have 

federalism implications. It will not have 

substantial direct effects on the States, 

on the relationship between the national 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government, as specified in 

Executive Order 13132. Pursuant to the 

terms of Executive Order 13132, it has 

been determined that this proposed rule 

does not have ‘‘federalism implications’’ 

because it does not meet the necessary 

criteria. Thus, the requirements of 

section 6 of the Executive Order do not 

apply to this proposed rule. 

In the spirit of Executive Order 13132, 

however, and consistent with our policy 

to promote communications between us 

and State and local governments, we 

specifically solicited comment on the 

proposed rule from State and local 

officials. 

F. Executive Order 13175—Consultation 

and Coordination With Indian Tribal 

Governments 

Executive Order 13175, entitled 

‘‘Consultation and Coordination with 

Indian Tribal Governments’’ (65 FR 

67249, November 9, 2000), requires EPA 

to develop an accountable process to 

ensure ‘‘meaningful and timely input by 

Tribal officials in the development of 

regulatory policies that have Tribal 

implications.’’ This final rule does not 

have ‘‘Tribal implications’’ as defined in 

Executive Order 13175. This rule 

concerns the NSR requirements for State 

and tribal implementation plans. The 

CAA provides for States to develop 

plans to regulate emissions of air 

pollutants within their jurisdictions. 

The Tribal Air Rule (TAR) under the 

CAA gives Tribes the opportunity to 

develop and implement CAA programs 

such as programs to attain and maintain 

the PM2.5 NAAQS, but it leaves to the 

discretion of the Tribe the decision of 

whether to develop these programs and 

which programs, or appropriate 

elements of a program, they will adopt. 

Although Executive Order 13175 does 

not apply to this rule, EPA did reach out 

to Tribal leaders and environmental 

staff in developing this rule. From 

2001–2004, the EPA supported a 

National Designations Workgroup to 

provide a forum for tribal professionals 

to give input to the designations 

process. In 2006, EPA supported a 

national ‘‘Tribal Air call’’ which 

provides an open forum for all Tribes to 

voice concerns to EPA about the 

NAAQS implementation process, 

including the PM2.5 NAAQS. In these 

meetings, EPA briefed call participants 

and Tribal environmental professionals 

gave input as the rule was under 

development. Furthermore, in December 

2005, EPA sent individualized letters to 

all federally recognized Tribes about the 

proposal to give Tribal leaders the 

opportunity for consultation. 

This final rule does not have Tribal 

implications as defined by Executive 


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Order 13175. It does not have a 

substantial direct effect on one or more 

Indian Tribes, since no Tribe has 

implemented a CAA program to attain 

the PM2.5 NAAQS at this time. The EPA 

notes that even if a Tribe were 

implementing such a plan at this time, 

while the rule might have Tribal 

implications with respect to that Tribe, 

it would not impose substantial direct 

costs upon it, nor would it preempt 

Tribal law. 

Furthermore, this rule does not affect 

the relationship or distribution of power 

and responsibilities between the Federal 

government and Indian Tribes. The 

CAA and the TAR establish the 

relationship of the Federal government 

and Tribes in developing plans to attain 

the NAAQS, and this rule does nothing 

to modify that relationship. As this rule 

does not have Tribal implications, 

Executive Order 13175 does not apply. 

G. Executive Order 13045—Protection of 

Children From Environmental Health 

and Safety Risks 

Executive Order 13045, entitled 

‘‘Protection of Children from 

Environmental Health Risks and Safety 

Risks’’ (62 FR 19885, April 23, 1997), 

applies to any rule that: (1) Is 

determined to be ‘‘economically 

significant’’ as defined under Executive 

Order 12866; and (2) concerns an 

environmental health or safety risk that 

we have reason to believe may have a 

disproportionate effect on children. If 

the regulatory action meets both criteria, 

the Agency must evaluate the 

environmental health or safety effects of 

the planned rule on children, and 

explain why the planned regulation is 

preferable to other potentially effective 

and reasonably feasible alternatives 

considered by the Agency. 

This final rule is not subject to the 

Executive Order because it is not 

economically significant as defined in 

Executive Order 12866, and because the 

Agency does not have reason to believe 

the environmental health or safety risks 

addressed by this action present a 

disproportionate risk to children. This 

rule does not impose any new 

requirements under the NSR program. 

However, in expanding the major NSR 

program to address PM2.5, we believe 

that this rule will serve to reduce 

environmental health risks to all 

citizens, including children, because 

one of the basic requirements of the 

major NSR program is that new and 

modified major stationary sources must 

not cause or contribute to air quality in 

violation of the NAAQS. 

H. Executive Order 13211—Actions 

That Significantly Affect Energy Supply, 

Distribution, or Use 

This rule is not a ‘‘significant energy 

action’’ as defined in Executive Order 

13211, ‘‘Actions Concerning Regulations 

That Significantly Affect Energy Supply, 

Distribution, or Use’’ (66 FR 28355 (May 

22, 2001)) because it is not likely to 

have a significant adverse effect on the 

supply, distribution, or use of energy. 

The final rule does not add any new 

requirements to the major NSR program; 

it simply expands the program to cover 

PM2.5 in addition to the several other 

pollutants already defined as regulated 

NSR pollutants. Although the major 

NSR program may apply to energy 

supply and distribution companies that 

build or significantly modify major 

sources of regulated NSR pollutants, we 

believe that any increase in 

expenditures for obtaining NSR permits 

that may result from this rule will be 

marginal rather than significant. 

I. National Technology Transfer and 

Advancement Act 

As noted in the proposed rule, section 

12(d) of the National Technology 

Transfer and Advancement Act of 1995 

(NTTAA), Public Law No. 104–113, 

12(d) (15 U.S.C. 272 note) directs us to 

use voluntary consensus standards 

(VCS) in our regulatory and 

procurement activities unless to do so 

would be inconsistent with applicable 

law or otherwise impractical. The VCS 

are technical standards (e.g., materials 

specifications, test methods, sampling 

procedures, and business practices) 

developed or adopted by one or more 

voluntary consensus bodies. The 

NTTAA directs us to provide Congress, 

through annual reports to OMB, with 

explanations when we do not use 

available and applicable VCS. 

This final rule does not involve 

technical standards. Therefore, we did 

not consider the use of any VCS. 

J. Executive Order 12898—Federal 

Actions to Address Environmental 

Justice in Minority Populations and 

Low-Income Populations 

Executive Order 12898 (59 FR 7629 

(Feb. 16, 1994)) establishes Federal 

executive policy on environmental 

justice. Its main provision directs 

Federal agencies, to the greatest extent 

practicable and permitted by law, to 

make environmental justice part of their 

mission by identifying and addressing, 

as appropriate, disproportionately high 

and adverse human health or 

environmental effects of its programs, 

policies, and activities on minorities 

and low-income populations in the 

United States. 

The EPA has determined that this 

final rule will not have 

disproportionately high and adverse 

human health or environmental effects 

on minority or low-income populations 

because it will have the effect of 

improving air quality. While it does not 

impose any new requirements under the 

major NSR program, we believe that this 

rule, in expanding the NSR program to 

address PM2.5, will serve to reduce 

adverse human health and 

environmental effects for all citizens, 

including minorities and low-income 

populations. 

K. Congressional Review Act 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. The EPA will 

submit a report containing this rule and 

other required information to the U.S. 

Senate, the U.S. House of 

Representatives, and the Comptroller 

General of the United States prior to 

publication of the rule in the Federal 

Register. A major rule cannot take effect 

until 60 days after it is published in the 

Federal Register. This action is not a 

‘‘major rule’’ as defined by 5 U.S.C. 

804(2). The rules affected by this action 

will be effective July 15, 2008. 

L. Petitions for Judicial Review 

Under section 307(b)(1) of the Act, 

petitions for judicial review of this 

action must be filed in the United States 

Court of Appeals for the District of 

Columbia Circuit by July 15, 2008. 

Filing a petition for reconsideration by 

the Administrator of this final rule does 

not affect the finality of this rule for the 

purposes of judicial review nor does it 

extend the time within which a petition 

for judicial review may be filed, and 

shall not postpone the effectiveness of 

such rule or action. This action may not 

be challenged later in proceedings to 

enforce its requirements. See Act 

section 307(b)(2). 

M. Determination Under Section 307(d) 

The PSD portions of this rulemaking, 

which implements part C of title I of the 

Act, are subject to the procedural 

requirements in section 307(d) of the 

Act. See section 307(d)(1)(J). In 

addition, pursuant to section 

307(d)(1)(V) of the Act, the 

Administrator determines that the NA 


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NSR portions of this action should also 

be subject to the provisions of section 

307(d) to ensure consistency. All of the 

procedural requirements of section 

307(d), e.g., docketing, hearing, and 

comment periods, have been complied 

with during the course of this 

rulemaking. 

VII. Statutory Authority 

The statutory authority for this action 

is provided by sections 101, 110, 165, 

169, 172, 173, 301, and 302 of the Act 

as amended (42 U.S.C. 7401, 7410, 7475, 

7479, 7502, 7503, 7601, and 7602). This 

rulemaking is also subject to section 

307(d) of the Act (42 U.S.C. 7407(d)). 

List of Subjects 

40 CFR Part 51 

Environmental protection, 

Administrative practices and 

procedures, Air pollution control, 

Intergovernmental relations. 

40 CFR Part 52 

Environmental protection, 

Administrative practices and 

procedures, Air pollution control, 

Intergovernmental relations. 

Dated: May 8, 2008. 

Stephen L. Johnson, 

Administrator. 

■ For the reasons stated in the preamble, 

title 40, chapter I of the Code of Federal 

Regulations is amended as follows. 

PART 51—[AMENDED] 

■ 1. The authority citation for part 51 

continues to read as follows: 

Authority: 23 U.S.C. 101; 42 U.S.C. 7401– 

7671q. 

Subpart I—[Amended] 

■ 2. Section 51.165 is amended as 

follows: 

■ a. By revising paragraph (a)(1)(x)(A); 

■ b. By removing the word ‘‘or’’ at the 

end of paragraph (a)(1)(xxxvii)(B); 

■ c. By revising paragraph 

(a)(1)(xxxvii)(C); 

■ d. By adding paragraph 

(a)(1)(xxxvii)(D); 

■ e. By redesignating paragraphs (a)(9)(i) 

through (iii) as paragraphs (a)(9)(ii) 

through (iv), respectively, and adding 

new paragraph (a)(9)(i); 

■ f. By removing from newly 

redesignated paragraph (a)(9)(iii) the 

reference to ‘‘paragraph (a)(9)(i)’’ and 

adding in its place ‘‘paragraph 

(a)(9)(ii)’’; and 

■ g. By adding paragraph (a)(11). 

§ 51.165 Permit requirements. 

(a) * * * 

(1) * * * 

(x)(A) Significant means, in reference 

to a net emissions increase or the 

potential of a source to emit any of the 

following pollutants, a rate of emissions 

that would equal or exceed any of the 

following rates: 

Pollutant Emission Rate 

Carbon monoxide: 100 tons per year 

(tpy) 

Nitrogen oxides: 40 tpy 

Sulfur dioxide: 40 tpy 

Ozone: 40 tpy of volatile organic 

compounds or nitrogen oxides 

Lead: 0.6 tpy 

PM10: 15 tpy 

PM2.5: 10 tpy of direct PM2.5 emissions; 

40 tpy of sulfur dioxide emissions; 40 

tpy of nitrogen oxide emissions unless 

demonstrated not to be a PM2.5

precursor under paragraph 

(a)(1)(xxxvii) of this section 

* * * * * 

(xxxvii) * * * 

(C) Any pollutant that is identified 

under this paragraph (a)(1)(xxxvii)(C) as 

a constituent or precursor of a general 

pollutant listed under paragraph 

(a)(1)(xxxvii)(A) or (B) of this section, 

provided that such constituent or 

precursor pollutant may only be 

regulated under NSR as part of 

regulation of the general pollutant. 

Precursors identified by the 

Administrator for purposes of NSR are 

the following: 

(1) Volatile organic compounds and 

nitrogen oxides are precursors to ozone 

in all ozone nonattainment areas. 

(2) Sulfur dioxide is a precursor to 

PM2.5 in all PM2.5 nonattainment areas. 

(3) Nitrogen oxides are presumed to 

be precursors to PM2.5 in all PM2.5

nonattainment areas, unless the State 

demonstrates to the Administrator’s 

satisfaction or EPA demonstrates that 

emissions of nitrogen oxides from 

sources in a specific area are not a 

significant contributor to that area’s 

ambient PM2.5 concentrations. 

(4) Volatile organic compounds and 

ammonia are presumed not to be 

precursors to PM2.5 in any PM2.5

nonattainment area, unless the State 

demonstrates to the Administrator’s 

satisfaction or EPA demonstrates that 

emissions of volatile organic 

compounds or ammonia from sources in 

a specific area are a significant 

contributor to that area’s ambient PM2.5

concentrations; or 

(D) PM2.5 emissions and PM10

emissions shall include gaseous 

emissions from a source or activity 

which condense to form particulate 

matter at ambient temperatures. On or 

after January 1, 2011 (or any earlier date 

established in the upcoming rulemaking 

codifying test methods), such 

condensable particulate matter shall be 

accounted for in applicability 

determinations and in establishing 

emissions limitations for PM2.5 and 

PM10 in nonattainment major NSR 

permits. Compliance with emissions 

limitations for PM2.5 and PM10 issued 

prior to this date shall not be based on 

condensable particulate matter unless 

required by the terms and conditions of 

the permit or the applicable 

implementation plan. Applicability 

determinations made prior to this date 

without accounting for condensable 

particulate matter shall not be 

considered in violation of this section 

unless the applicable implementation 

plan required condensable particulate 

matter to be included. 

* * * * * 

(9)(i) The plan shall require that in 

meeting the emissions offset 

requirements of paragraph (a)(3) of this 

section, the ratio of total actual 

emissions reductions to the emissions 

increase shall be at least 1:1 unless an 

alternative ratio is provided for the 

applicable nonattainment area in 

paragraphs (a)(9)(ii) through (a)(9)(iv) of 

this section. 

* * * * * 

(11) The plan shall require that in 

meeting the emissions offset 

requirements of paragraph (a)(3) of this 

section, the emissions offsets obtained 

shall be for the same regulated NSR 

pollutant unless interprecursor 

offsetting is permitted for a particular 

pollutant as specified in this paragraph. 

The plan may allow the offset 

requirements in paragraph (a)(3) of this 

section for direct PM2.5 emissions or 

emissions of precursors of PM2.5 to be 

satisfied by offsetting reductions in 

direct PM2.5 emissions or emissions of 

any PM2.5 precursor identified under 

paragraph (a)(1)(xxxvii)(C) of this 

section if such offsets comply with the 

interprecursor trading hierarchy and 

ratio established in the approved plan 

for a particular nonattainment area. 

* * * * * 

■ 3. Section 51.166 is amended as 

follows: 

■ a. By revising paragraphs (b)(23)(i) 

and (b)(49)(i); 

■ b. By removing the word ‘‘or’’ at the 

end of paragraph (b)(49)(iii); 

■ c. By adding and reserving paragraph 

(b)(49)(v); 

■ d. By adding paragraph (b)(49)(vi); 

and 

■ e. By revising paragraphs (i)(5)(ii) and 

(i)(5)(iii). 


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§ 51.166 Prevention of significant 

deterioration of air quality. 

* * * * * 

(b) * * * 

(23)(i) Significant means, in reference 

to a net emissions increase or the 

potential of a source to emit any of the 

following pollutants, a rate of emissions 

that would equal or exceed any of the 

following rates: 

Pollutant and Emissions Rate 

Carbon monoxide: 100 tons per year 

(tpy) 

Nitrogen oxides: 40 tpy 

Sulfur dioxide: 40 tpy 

Particulate matter: 25 tpy of particulate 

matter emissions. 15 tpy of PM10

emissions 

PM2.5: 10 tpy of direct PM2.5 emissions; 

40 tpy of sulfur dioxide emissions; 40 

tpy of nitrogen oxide emissions unless 

demonstrated not to be a PM2.5

precursor under paragraph (b)(49) of 

this section 

Ozone: 40 tpy of volatile organic 

compounds or nitrogen oxides 

Lead: 0.6 tpy 

Fluorides: 3 tpy 

Sulfuric acid mist: 7 tpy 

Hydrogen sulfide (H2S): 10 tpy 

Total reduced sulfur (including H2S): 10 

tpy 

Reduced sulfur compounds (including 

H2S): 10 tpy 

Municipal waste combustor organics 

(measured as total tetra-through octachlorinated dibenzo-p-dioxins and 

dibenzofurans): 3.2 × 10–¥6

megagrams per year (3.5 × 10¥6 tons 

per year) 

Municipal waste combustor metals 

(measured as particulate matter): 14 

megagrams per year (15 tons per year) 

Municipal waste combustor acid gases 

(measured as sulfur dioxide and 

hydrogen chloride): 36 megagrams per 

year (40 tons per year) 

Municipal solid waste landfill 

emissions (measured as nonmethane 

organic compounds): 45 megagrams 

per year (50 tons per year) 

* * * * * 

(49) * * * 

(i) Any pollutant for which a national 

ambient air quality standard has been 

promulgated and any pollutant 

identified under this paragraph (b)(49)(i) 

as a constituent or precursor to such 

pollutant. Precursors identified by the 

Administrator for purposes of NSR are 

the following: 

(a) Volatile organic compounds and 

nitrogen oxides are precursors to ozone 

in all attainment and unclassifiable 

areas. 

(b) Sulfur dioxide is a precursor to 

PM2.5 in all attainment and 

unclassifiable areas. 

(c) Nitrogen oxides are presumed to 

be precursors to PM2.5 in all attainment 

and unclassifiable areas, unless the 

State demonstrates to the 

Administrator’s satisfaction or EPA 

demonstrates that emissions of nitrogen 

oxides from sources in a specific area 

are not a significant contributor to that 

area’s ambient PM2.5 concentrations. 

(d) Volatile organic compounds are 

presumed not to be precursors to PM2.5

in any attainment or unclassifiable area, 

unless the State demonstrates to the 

Administrator’s satisfaction or EPA 

demonstrates that emissions of volatile 

organic compounds from sources in a 

specific area are a significant 

contributor to that area’s ambient PM2.5

concentrations. 

* * * * * 

(v) [Reserved.] 

(vi) Particulate matter (PM) emissions, 

PM2.5 emissions, and PM10 emissions 

shall include gaseous emissions from a 

source or activity which condense to 

form particulate matter at ambient 

temperatures. On or after January 1, 

2011 (or any earlier date established in 

the upcoming rulemaking codifying test 

methods), such condensable particulate 

matter shall be accounted for in 

applicability determinations and in 

establishing emissions limitations for 

PM, PM2.5 and PM10 in PSD permits. 

Compliance with emissions limitations 

for PM, PM2.5 and PM10 issued prior to 

this date shall not be based on 

condensable particular matter unless 

required by the terms and conditions of 

the permit or the applicable 

implementation plan. Applicability 

determinations made prior to this date 

without accounting for condensable 

particular matter shall not be considered 

in violation of this section unless the 

applicable implementation plan 

required condensable particular matter 

to be included. 

* * * * * 

(i) * * * 

(5) * * * 

(ii) The concentrations of the 

pollutant in the area that the source or 

modification would affect are less than 

the concentrations listed in paragraph 

(i)(5)(i) of this section; or 

(iii) The pollutant is not listed in 

paragraph (i)(5)(i) of this section. 

* * * * * 

■ 4. Appendix S to Part 51 is amended 

as follows: 

■ a. By revising paragraphs II.A.10(i) 

and II.A.31; 

■ b. By revising paragraph IV.A, 

Condition 3; 

■ c. By redesignating paragraphs IV.G.1 

through IV.G.3 as paragraphs IV.G.2 

through IV.G.4, respectively, and adding 

new paragraph IV.G.1; 

■ d. By removing from newly 

redesignated paragraph IV.G.3 the 

reference to ‘‘paragraph IV.G.1’’ and 

adding in its place ‘‘paragraph IV.G.2’’; 

and 

■ e. By adding paragraph IV.G.5. 

Appendix S to Part 51—Emission Offset 

Interpretative Ruling 

* * * * * 

II. * * * 

A. * * * 

10. (i) Significant means, in reference to a 

net emissions increase or the potential of a 

source to emit any of the following 

pollutants, a rate of emissions that would 

equal or exceed any of the following rates: 

Pollutant and Emissions Rate 

Carbon monoxide: 100 tons per year (tpy) 

Nitrogen oxides: 40 tpy 

Sulfur dioxide: 40 tpy 

Ozone: 40 tpy of volatile organic compounds 

or nitrogen oxides 

Lead: 0.6 tpy 

Particulate matter: 25 tpy of particulate 

matter emissions 

PM10: 15 tpy 

PM2.5: 10 tpy of direct PM2.5 emissions; 40 

tpy of sulfur dioxide emissions 

* * * * * 

31. Regulated NSR pollutant, for purposes 

of this Ruling, means the following: 

(i) Nitrogen oxides or any volatile organic 

compounds; 

(ii) Any pollutant for which a national 

ambient air quality standard has been 

promulgated; 

(iii) Any pollutant that is identified under 

this paragraph II.A.31(iii) as a constituent or 

precursor of a general pollutant listed under 

paragraph II.A.31(i) or (ii) of this Ruling, 

provided that such constituent or precursor 

pollutant may only be regulated under NSR 

as part of regulation of the general pollutant. 

Precursors identified by the Administrator 

for purposes of NSR are the following: 

(a) Volatile organic compounds and 

nitrogen oxides are precursors to ozone in all 

ozone nonattainment areas. 

(b) Sulfur dioxide is a precursor to PM2.5

in all PM2.5 nonattainment areas; or 

(iv) Particulate matter (PM) emissions, 

PM2.5 emissions and PM10 emissions shall 

include gaseous emissions from a source or 

activity which condense to form particulate 

matter at ambient temperatures. On or after 

January 1, 2011 (or any earlier date 

established in the upcoming rulemaking 

codifying test methods), such condensable 

particulate matter shall be accounted for in 

applicability determinations and in 

establishing emissions limitations for PM, 

PM2.5 and PM10 in permits issued under this 

ruling. Compliance with emissions 

limitations for PM, PM2.5 and PM10 issued 

prior to this date shall not be based on 

condensable particulate matter unless 

required by the terms and conditions of the 

permit or the applicable implementation 

plan. Applicability determinations made 

prior to this date without accounting for 

condensable particulate matter shall not be 


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considered in violation of this section unless 

the applicable implementation plan required 

condensable particulate matter to be 

included. 

* * * * * 

IV. * * * 

A. * * * 

Condition 3. Emission reductions (offsets) 

from existing sources 5 in the area of the 

proposed source (whether or not under the 

same ownership) are required such that there 

will be reasonable progress toward 

attainment of the applicable NAAQS.6 Except 

as provided in paragraph IV.G.5 of this 

Ruling (addressing PM2.5 and its precursors), 

only intrapollutant emission offsets will be 

acceptable (e.g., hydrocarbon increases may 

not be offset against SO2 reductions). 5Subject to the provisions of paragraph 

IV.C of this Ruling. 6The discussion in this paragraph is a 

proposal, but represents EPA’s interim policy 

until final rulemaking is completed. 

* * * * * 

G. Offset ratios. 

1. In meeting the emissions offset 

requirements of paragraph IV.A, Condition 3 

of this Ruling, the ratio of total actual 

emissions reductions to the emissions 

increase shall be at least 1:1 unless an 

alternative ratio is provided for the 

applicable nonattainment area in paragraphs 

IV.G.2 through IV.G.4. 

* * * * * 

5. Interpollutant offsetting. In meeting the 

emissions offset requirements of paragraph 

IV.A, Condition 3 of this Ruling, the 

emissions offsets obtained shall be for the 

same regulated NSR pollutant unless 

interpollutant offsetting is permitted for a 

particular pollutant as specified in this 

paragraph IV.G.5. The offset requirements of 

paragraph IV.A, Condition 3 of this Ruling 

for direct PM2.5 emissions or emissions of 

precursors of PM2.5 may be satisfied by 

offsetting reductions of direct PM2.5

emissions or emissions of any PM2.5

precursor identified under paragraph II.A.31 

(iii) of this Ruling if such offsets comply with 

an interprecursor trading hierarchy and ratio 

approved by the Administrator. 

* * * * * 

PART 52—[AMENDED] 

■ 5. The authority citation for part 52 

continues to read as follows: 

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

Subpart A—[Amended] 

■ 6. Section 52.21 is amended as 

follows: 

■ a. By revising paragraphs (b)(23)(i) 

and (b)(50)(i); 

■ b. By removing the word ‘‘or’’ at the 

end of paragraph (b)(50)(iii); 

■ c. By adding and reserving paragraph 

(b)(50)(v); 

■ d. By adding paragraphs (b)(50)(vi) 

and (i)(1)(xi); 

■ e. By revising paragraph (i)(5)(ii); and 

■ f. By adding paragraph (i)(5)(iii). 

§ 52.21 Prevention of significant 

deterioration of air quality. 

* * * * * 

(b) * * * 

(23)(i) Significant means, in reference 

to a net emissions increase or the 

potential of a source to emit any of the 

following pollutants, a rate of emissions 

that would equal or exceed any of the 

following rates: 

Pollutant and Emissions Rate 

Carbon monoxide: 100 tons per year 

(tpy) 

Nitrogen oxides: 40 tpy 

Sulfur dioxide: 40 tpy 

Particulate matter: 25 tpy of particulate 

matter emissions 

PM10: 15 tpy 

PM2.5: 10 tpy of direct PM2.5 emissions; 

40 tpy of sulfur dioxide emissions; 40 

tpy of nitrogen oxide emissions unless 

demonstrated not to be a PM2.5

precursor under paragraph (b)(50) of 

this section 

Ozone: 40 tpy of volatile organic 

compounds or nitrogen oxides 

Lead: 0.6 tpy 

Fluorides: 3 tpy 

Sulfuric acid mist: 7 tpy 

Hydrogen sulfide (H2S): 10 tpy 

Total reduced sulfur (including H2S): 10 

tpy 

Reduced sulfur compounds (including 

H2S): 10 tpy 

Municipal waste combustor organics 

(measured as total tetra-through octachlorinated dibenzo-p-dioxins and 

dibenzofurans): 3.2 × 10 6

megagrams per year (3.5 × 10 6

tons per year) 

Municipal waste combustor metals 

(measured as particulate matter): 14 

megagrams per year (15 tons per year) 

Municipal waste combustor acid gases 

(measured as sulfur dioxide and 

hydrogen chloride): 36 megagrams per 

year (40 tons per year) 

Municipal solid waste landfills 

emissions (measured as nonmethane 

organic compounds): 45 megagrams 

per year (50 tons per year) 

* * * * * 

(50) * * * 

(i) Any pollutant for which a national 

ambient air quality standard has been 

promulgated and any pollutant 

identified under this paragraph (b)(50)(i) 

as a constituent or precursor for such 

pollutant. Precursors identified by the 

Administrator for purposes of NSR are 

the following: 

(a) Volatile organic compounds and 

nitrogen oxides are precursors to ozone 

in all attainment and unclassifiable 

areas. 

(b) Sulfur dioxide is a precursor to 

PM2.5 in all attainment and 

unclassifiable areas. 

(c) Nitrogen oxides are presumed to 

be precursors to PM2.5 in all attainment 

and unclassifiable areas, unless the 

State demonstrates to the 

Administrator’s satisfaction or EPA 

demonstrates that emissions of nitrogen 

oxides from sources in a specific area 

are not a significant contributor to that 

area’s ambient PM2.5 concentrations. 

(d) Volatile organic compounds are 

presumed not to be precursors to PM2.5

in any attainment or unclassifiable area, 

unless the State demonstrates to the 

Administrator’s satisfaction or EPA 

demonstrates that emissions of volatile 

organic compounds from sources in a 

specific area are a significant 

contributor to that area’s ambient PM2.5

concentrations. 

* * * * * 

(v) [Reserved.] 

(vi) Particulate matter (PM) emissions, 

PM2.5 emissions and PM10 emissions 

shall include gaseous emissions from a 

source or activity which condense to 

form particulate matter at ambient 

temperatures. On or after January 1, 

2011 (or any earlier date established in 

the upcoming rulemaking codifying test 

methods), such condensable particulate 

matter shall be accounted for in 

applicability determinations and in 

establishing emissions limitations for 

PM, PM2.5 and PM10 in PSD permits. 

Compliance with emissions limitations 

for PM, PM2.5 and PM10 issued prior to 

this date shall not be based on 

condensable particular matter unless 

required by the terms and conditions of 

the permit or the applicable 

implementation plan. Applicability 

determinations made prior to this date 

without accounting for condensable 

particular matter shall not be considered 

in violation of this section unless the 

applicable implementation plan 

required condensable particular matter 

to be included. 

* * * * * 

(i) * * * 

(1) * * * 

(xi) The source or modification was 

subject to 40 CFR 52.21, with respect to 

PM2.5, as in effect before July 15, 2008, 

and the owner or operator submitted an 

application for a permit under this 

section before that date consistent with 

EPA recommendations to use PM10 as a 

surrogate for PM2.5, and the 

Administrator subsequently determines 

that the application as submitted was 

complete with respect to the PM2.5

requirements then in effect, as 

interpreted in the EPA memorandum 

entitled ‘‘Interim Implementation of 

New Source Review Requirements for 

PM2.5’’ (October 23, 1997). Instead, the 

requirements of paragraphs (j) through 


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(r) of this section, as interpreted in the 

aforementioned memorandum, that 

were in effect before July 15, 2008 shall 

apply to such source or modification. 

* * * * * 

(5) * * * 

(ii) The concentrations of the 

pollutant in the area that the source or 

modification would affect are less than 

the concentrations listed in paragraph 

(i)(5)(i) of this section; or 

(iii) The pollutant is not listed in 

paragraph (i)(5)(i) of this section. 

* * * * * 

[FR Doc. E8–10768 Filed 5–15–08; 8:45 am] 

BILLING CODE 6560–50–P 

DEPARTMENT OF HOMELAND 

SECURITY 

Federal Emergency Management 

Agency 

44 CFR Part 67 

Final Flood Elevation Determinations 

AGENCY: Federal Emergency 

Management Agency, DHS. 

ACTION: Final rule. 

SUMMARY: Base (1% annual chance) 

Flood Elevations (BFEs) and modified 

BFEs are made final for the 

communities listed below. The BFEs 

and modified BFEs are the basis for the 

floodplain management measures that 

each community is required either to 

adopt or to show evidence of being 

already in effect in order to qualify or 

remain qualified for participation in the 

National Flood Insurance Program 

(NFIP). 

DATES: The date of issuance of the Flood 

Insurance Rate Map (FIRM) showing 

BFEs and modified BFEs for each 

community. This date may be obtained 

by contacting the office where the maps 

are available for inspection as indicated 

on the table below. 

ADDRESSES: The final BFEs for each 

community are available for inspection 

at the office of the Chief Executive 

Officer of each community. The 

respective addresses are listed in the 

table below. 

FOR FURTHER INFORMATION CONTACT: 

William R. Blanton, Jr., Engineering 

Management Branch, Mitigation 

Directorate, Federal Emergency 

Management Agency, 500 C Street, SW., 

Washington, DC 20472, (202) 646–3151. 

SUPPLEMENTARY INFORMATION: The 

Federal Emergency Management Agency 

(FEMA) makes the final determinations 

listed below for the modified BFEs for 

each community listed. These modified 

elevations have been published in 

newspapers of local circulation and 

ninety (90) days have elapsed since that 

publication. The Assistant 

Administrator of the Mitigation 

Directorate has resolved any appeals 

resulting from this notification. 

This final rule is issued in accordance 

with section 110 of the Flood Disaster 

Protection Act of 1973, 42 U.S.C. 4104, 

and 44 CFR part 67. FEMA has 

developed criteria for floodplain 

management in floodprone areas in 

accordance with 44 CFR part 60. 

Interested lessees and owners of real 

property are encouraged to review the 

proof Flood Insurance Study and FIRM 

available at the address cited below for 

each community. The BFEs and 

modified BFEs are made final in the 

communities listed below. Elevations at 

selected locations in each community 

are shown. 

National Environmental Policy Act. 

This final rule is categorically excluded 

from the requirements of 44 CFR part 

10, Environmental Consideration. An 

environmental impact assessment has 

not been prepared. 

Regulatory Flexibility Act. As flood 

elevation determinations are not within 

the scope of the Regulatory Flexibility 

Act, 5 U.S.C. 601–612, a regulatory 

flexibility analysis is not required. 

Regulatory Classification. This final 

rule is not a significant regulatory action 

under the criteria of section 3(f) of 

Executive Order 12866 of September 30, 

1993, Regulatory Planning and Review, 

58 FR 51735. 

Executive Order 13132, Federalism. 

This final rule involves no policies that 

have federalism implications under 

Executive Order 13132. 

Executive Order 12988, Civil Justice 

Reform. This final rule meets the 

applicable standards of Executive Order 

12988. 

List of Subjects in 44 CFR Part 67 

Administrative practice and 

procedure, Flood insurance, Reporting 

and recordkeeping requirements. 

■ Accordingly, 44 CFR part 67 is 

amended as follows: 

PART 67—[AMENDED] 

■ 1. The authority citation for part 67 

continues to read as follows: 

Authority: 42 U.S.C. 4001 et seq.; 

Reorganization Plan No. 3 of 1978, 3 CFR, 

1978 Comp., p. 329; E.O. 12127, 44 FR 19367, 

3 CFR, 1979 Comp., p. 376. 

§ 67.11 [Amended] 

■ 2. The tables published under the 

authority of § 67.11 are amended as 

follows: 

Flooding source(s) Location of referenced elevation 

* Elevation in feet 

(NGVD) 

+ Elevation in feet 

(NAVD) 

# Depth in feet 

above ground 

Modified 

Communities 

affected 

Randolph County, Illinois, and Incorporated Areas 

Docket No.: FEMA–B–7740 

Kaskaskia River ..................... At confluence with Mississippi River ..................................... +392 Village of Evansville, Unincorporated Areas of Randolph 

County. 

Randolph/Monroe County boundary (approximately 700 

feet upstream Anna Lane extended).

+392 

Mississippi River .................... Jackson/Randolph County boundary (approximately Cora 

Road extended).

+382 City of Chester, Unincorporated Areas of Randolph 

County, Village of 

Kaskaskia, Village of Prairie Du Rocher, Village of 

Rockwood. 


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64864 Federal Register / Vol. 75, No. 202 / Wednesday, October 20, 2010 / Rules and Regulations 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Parts 51 and 52 

[EPA–HQ–OAR–2006–0605; FRL–9210–9] 

RIN 2060–AO24 

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) 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The EPA is amending the 

requirements for particulate matter less 

than 2.5 micrometers (PM2.5) under the 

Prevention of Significant Deterioration 

(PSD) program by adding maximum 

allowable increases in ambient pollutant 

concentrations (‘‘increments’’) and two 

screening tools, known as the 

Significant Impact Levels (SILs) and a 

Significant Monitoring Concentration 

(SMC) for PM2.5. The SILs for PM2.5 are 

also being added to two other New 

Source Review (NSR) rules that regulate 

the construction and modification of 

any major stationary source locating in 

an attainment or unclassifiable area, 

where the source’s emissions may cause 

or contribute to a violation of the 

national ambient air quality standards 

(NAAQS). 

DATES: This final rule is effective on 

December 20, 2010. 

ADDRESSES: The EPA has established a 

docket for this action under Docket ID 

No. EPA–HQ–OAR–2006–0605. All 

documents in the docket are listed on 

the http://www.regulations.gov Web 

Site. Although listed in the index, some 

information may not be publicly 

available, e.g., Confidential Business 

Information (CBI) or other information 

whose disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the Internet and will be publicly 

available only in hard copy form. 

Publicly available docket materials are 

available either electronically through 

http://www.regulations.gov or in hard 

copy at the Air Docket, EPA/DC, EPA 

West, Room 3334, 1301 Constitution 

Avenue, Northwest, Washington, DC. 

The Public Reading Room is open from 

8:30 a.m. to 4:30 p.m., Monday through 

Friday, excluding legal holidays. The 

telephone number for the Public 

Reading Room is (202) 566–1744, and 

the telephone number for the Air Docket 

is (202) 566–1742. 

FOR FURTHER INFORMATION CONTACT: Mr. 

Dan deRoeck, Air Quality Policy 

Division, Office of Air Quality Planning 

and Standards (C504–03), U.S. 

Environmental Protection Agency, 

Research Triangle Park, North Carolina 

27711, telephone number: (919) 541– 

5593, facsimile number: (919) 541–5509, 

e-mail address: deroeck.dan@epa.gov. 

SUPPLEMENTARY INFORMATION: The 

information in this Supplementary 

Information section of this preamble is 

organized as follows: 

I. General Information 

A. Does this action apply to me? 

B. Where can I get a copy of this document 

and other related information? 

II. Purpose 

III. Overview of Final PM2.5 PSD Regulations 

A. Increments 

B. Significant Impact Levels 

C. Significant Monitoring Concentration 

IV. Background 

A. PSD Program 

B. History of Particulate Matter (PM) 

NAAQS 

1. Total Suspended Particulate (TSP) and 

PM10 NAAQS 

2. PM2.5 NAAQS 

3. Revised PM2.5 and PM10 NAAQS 

C. Implementation of NSR for PM2.5

D. Increments Under the PSD Program 

E. Historical Approaches for Developing 

Increments 

1. Congressional Enactment of Increments 

for PM and SO2

2. EPA’s Promulgation of Increments for 

NO2 and PM10

a. Increments for NO2 Using the 

‘‘Contingent Safe Harbor’’ Approach 

Under Section 166(a) of the Act 

b. Increments for PM10 Using ‘‘Equivalent 

Substitution’’ Approach Under Section 

166(f) of the Act 

V. Final Action on PM2.5 Increments 

A. Decision To Establish PM2.5 Increments 

Using ‘‘Contingent Safe Harbor 

Approach’’ Under Section 166(a) 

B. Rationale for the Applicability of 

Section 166(a) 

C. EPA’s Interpretation of the 

Requirements Under Sections 166(a)–(d) 

of the Act 

1. Regulations as a Whole Should Fulfill 

Statutory Requirements 

2. Contingent Safe Harbor Approach 

3. The Statutory Factors Applicable Under 

Section 166(c) 

4. Balancing the Factors Applicable Under 

Section 166(c) 

5. Authority for States To Adopt 

Alternatives to Increments 

D. Framework for Pollutant-Specific PSD 

Regulations for PM2.5

1. Increment System 

2. Area Classifications 

3. Permitting Procedures 

4. AQRV Review by Federal Land Manager 

(FLM) and Reviewing Authority 

5. Additional Impacts Analysis 

6. Installation of BACT 

E. Final PM2.5 Increments 

1. Identification of Safe Harbor Increments 

2. Data Used by EPA for the Evaluation of 

the Safe Harbor Increments for PM2.5

3. Scope of Effects Considered 

4. Evaluation of the Health and Welfare 

Effects of PM2.5

a. Health Effects 

b. Welfare Effects 

5. Fundamental Elements of Increments 

6. Evaluation of the Safe Harbor Increments 

7. Compliance Determinations for the 

PM2.5 Increments 

a. Modeling Compliance With PM2.5

Increments 

b. Condensable PM 

c. PM2.5 Precursors 

F. Final Action on Trigger and Baseline 

Dates for PM2.5 Increments 

G. Definition of ‘‘Baseline Area’’ for PM2.5

H. No Final Action With Respect to the 

Proposed Revocation of PM10 Annual 

Increments 

I. Other Comments on Increments 

VI. Final Action on PM2.5 SILs 

A. EPA’s Determination on SILs for PM2.5

B. Response to Comments Concerning the 

SILs 

1. Legal Basis for SILs 

2. Levels of the SILs 

a. Class I SILs 

b. Class II and III SILs 

3. Relationship Between SILs and AQRVs 

4. Form of the SILs 

5. SILs for Other Pollutants 

VII. Final Action on the PM2.5 SMC 

A. EPA’s Determination on the PM2.5 SMC 

B. Response to Comments Concerning the 

SMC 

1. Legal Issues 

2. Level of the SMC 

C. Correction of Cross Reference in PSD 

Ambient Monitoring Requirements 

VIII. Dates Associated With Implementation 

of the Final Rule 

A. Effective Date of the Final Rule 

1. State PSD Programs 

2. Federal PSD Program 

B. Transition Period 

C. SILs and SMC for PM2.5

IX. Other Regulatory Changes 

X. Statutory and Executive Order Reviews 

A. Executive Order 12866—Regulatory 

Planning and Review 

B. Paperwork Reduction Act 

C. Regulatory Flexibility Act 

D. Unfunded Mandates Reform Act 

E. Executive Order 13132—Federalism 

F. Executive Order 13175—Consultation 

and Coordination With Indian Tribal 

Governments 

G. Executive Order 13045—Protection of 

Children From Environmental Health 

and Safety Risks 

H. Executive Order 13211—Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer and 

Advancement Act 

J. Executive Order 12898—Federal Actions 

To Address Environmental Justice in 

Minority Populations and Low-Income 

Populations 

K. Congressional Review Act 

XI. Judicial Review 

XII. Statutory Authority 


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I. General Information 

A. Does this action apply to me? 

Entities affected by this rule include 

sources in all industry groups. The 

majority of sources potentially affected 

are expected to be in the following 

groups: 

Industry group NAICSa

Electric services ................................................................................................................................................... 221111, 221112, 221113, 221119, 

221121, 221122 

Petroleum refining ............................................................................................................................................... 32411 

Industrial inorganic chemicals ............................................................................................................................. 325181, 32512, 325131, 325182, 

211112, 325998, 331311, 

325188 

Industrial organic chemicals ................................................................................................................................ 32511, 325132, 325192, 325188, 

325193, 32512, 325199 

Miscellaneous chemical products ........................................................................................................................ 32552, 32592, 32591, 325182, 

32551 

Natural gas liquids ............................................................................................................................................... 211112 

Natural gas transport ........................................................................................................................................... 48621, 22121 

Pulp and paper mills ............................................................................................................................................ 32211, 322121, 322122, 32213 

Paper mills ........................................................................................................................................................... 322121, 322122 

Automobile manufacturing ................................................................................................................................... 336111, 336112, 336712, 336211, 

336992, 336322, 336312, 

33633, 33634, 33635, 336399, 

336212, 336213 

Pharmaceuticals .................................................................................................................................................. 325411, 325412, 325413, 325414 

a North American Industry Classification System. 

Entities affected by this rule also 

include State and local permitting 

authorities, and tribal authorities that 

implement these regulations. 

B. Where can I get a copy of this 

document and other related 

information? 

In addition to being available in the 

docket, an electronic copy of this final 

rule will also be available on the World 

Wide Web. Following signature by the 

EPA Administrator, a copy of this final 

rule will be posted in the regulations 

and standards section of our NSR home 

page located at http://www.epa.gov/nsr. 

II. Purpose 

The purpose of this rulemaking is to 

finalize certain program provisions 

under the regulations to prevent 

significant deterioration of air quality 

due to emissions of PM2.5 (i.e., under the 

PM2.5 PSD regulations). This final rule 

supplements the final implementation 

rule for PM2.5, known as the Clean Air 

Fine Particle Implementation Rule 

(CAFPIR) that we promulgated on April 

25, 2007 (72 FR 20586), and the PM2.5

NSR Implementation Rule that we 

promulgated on May 16, 2008 (73 FR 

28321). Together, these three rules 

encompass the elements necessary for 

implementation of a PM2.5 program in 

any area. This final rule is important 

because it establishes increments, SILs, 

and an SMC for PM2.5 to facilitate 

ambient air quality monitoring and 

modeling under the PSD regulations for 

areas designated attainment or 

unclassifiable for PM2.5. 

III. Overview of Final PM2.5 PSD 

Regulations 

A. Increments 

This rulemaking establishes 

increments for PM2.5 pursuant to the 

legal authority contained in section 

166(a) of the Clean Air Act (CAA or Act) 

for pollutants for which NAAQS are 

promulgated after 1977. The final PM2.5

increments were identified as Option 1 

in the 2007 Notice of Proposed 

Rulemaking (NPRM) for this action, and 

are as follows: 

Averaging period NAAQS 

(μg/m3) 

Increments (μg/m3) 

Class I Class II Class III 

Annual .............................................................................................................................. 15 1 4 8 

24-hour ............................................................................................................................. 35 2 9 18 

As discussed in more detail in 

sections V.F and VIII, the increments for 

PM2.5 will become applicable on 

October 20, 2011 in order to comply 

with section 166(b) of the Act 

(providing that regulations under 

section 166(a) ‘‘shall become effective 

one year after the date of 

promulgation’’). 

This final rule does not revoke the 

annual increments for particulate matter 

less than 10 micrometers (PM10) as 

proposed under Option 1 in the 2007 

NPRM. Thus, we are retaining the 24- 

hour and annual PM10 increments in 

addition to adding PM2.5 increments. 

This outcome is discussed in greater 

detail in section V.H of this preamble. 

B. Significant Impact Levels 

This rule establishes SILs for PM2.5 for 

evaluating the impact a proposed new 

source or modification may have on the 

NAAQS and PSD increments for PM2.5. 

The SILs for PM2.5 were developed by 

scaling the existing PM10 SILs using a 

PM2.5-to-PM10 NAAQS ratio. The final 

SILs were identified as Option 3 in the 

2007 NPRM, and are as follows: 


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1We have delegated our authority to some states 

to implement the Federal PSD program. The EPA 

remains the reviewing authority in non-delegated 

states lacking SIP-approved programs and in Indian 

country. 

Averaging period 

SILs (μg/m3) 

Class I Class II Class III 

Annual ...................................................................................................................................................... 0.06 0.3 0.3 

24-hour ..................................................................................................................................................... 0.07 1.2 1.2 

These values will be added to the 

State implementation plan (SIP) 

provisions for PSD at 40 CFR 51.166 (as 

an optional screening tool) and the 

Federal PSD program at 40 CFR 52.21, 

as well as under the preconstruction 

review permit requirements at 40 CFR 

51.165(b) and part 51, Appendix S. See 

a more detailed discussion of the SILs, 

as well as the relevant comments and 

our responses to them, in section VI of 

this preamble. The SILs for PM2.5 are 

incorporated into the Federal PSD 

program as well as into the regulations 

for State-implemented PSD programs, 

although they are regarded as optional 

for State programs. The effective date for 

implementing the SILs under the 

Federal PSD program is the effective 

date of this final rule. See section VIII 

of this preamble for further discussion 

of the effective date. 

C. Significant Monitoring Concentration 

This final rule establishes the SMC for 

PM2.5 as 4 μg/m3 PM2.5 (24-hour 

average). This value has been developed 

pursuant to proposed Option 1; 

however, it should be noted that the 

value being established in this final rule 

is lower than the proposed value of 10 

μg/m3 that was originally developed 

under Option 1. A more detailed 

discussion of the proposed SMC is 

presented in section VII of this 

preamble, describing the rationale for 

altering the proposed SMC, and the 

relevant comments on the proposed 

SMC and our responses to them. The 

SMC for PM2.5 is incorporated into the 

Federal PSD program as well as into the 

regulations for State-implemented PSD 

programs, although they are regarded as 

optional for State programs. As with the 

SILs for PM2.5, the effective date for 

implementing the SMC under the 

Federal PSD program is the effective 

date of this final rule. See section VIII 

of this preamble for further discussion 

of the effective date. 

IV. Background 

A. PSD Program 

The NSR provisions of the Act are a 

combination of air quality planning and 

air pollution control technology 

program requirements for new and 

modified stationary sources of air 

pollution. In brief, section 109 of the 

Act requires us to promulgate primary 

NAAQS to protect public health and 

secondary NAAQS to protect public 

welfare. Once we have set these 

standards, states must develop, adopt, 

and submit to us for approval SIPs that 

contain emission limitations and other 

control measures to attain and maintain 

the NAAQS and to meet the other 

requirements of section 110(a) of the 

Act. Part C of title I of the Act contains 

the requirements for a component of the 

major NSR program known as the PSD 

program. This program sets forth 

procedures for the preconstruction 

review and permitting of new and 

modified major stationary sources of air 

pollution locating in areas meeting the 

NAAQS (‘‘attainment’’ areas) and areas 

for which there is insufficient 

information to classify an area as either 

attainment or nonattainment 

(‘‘unclassifiable’’ areas). Most states have 

SIP-approved preconstruction permit 

(major NSR) programs. The Federal PSD 

program at 40 CFR 52.21 applies in 

some states that lack a SIP-approved 

permit program, and in Indian country.1

The applicability of the PSD program to 

a major stationary source must be 

determined in advance of construction 

and is a pollutant-specific 

determination. Once a major source is 

determined to be subject to the PSD 

program (PSD source), among other 

requirements, it must undertake a series 

of analyses to demonstrate that it will 

use the best available control technology 

(BACT) and will not cause or contribute 

to a violation of any NAAQS or 

increment. For the latter demonstration, 

the PSD regulations generally require 

sources to submit for review and 

approval a source impact analysis and 

an air quality analysis. 

The source impact analysis is 

primarily a modeling analysis designed 

to show that the allowable emissions 

increase from the proposed project, in 

conjunction with other emissions 

increases from existing sources, will not 

result in a violation of either the 

NAAQS or increments. In cases where 

the source’s emissions may adversely 

affect an area classified as a Class I area, 

additional review is conducted to 

protect the increments and special 

attributes of such an area defined as ‘‘air 

quality related values’’ (AQRVs). 

The air quality analysis must assess 

the ambient air quality in the area that 

the proposed project would affect. For 

this analysis, the owner or operator of 

the proposed project must submit as 

part of a complete permit application air 

quality monitoring data that represent 

the air quality in the area affected by the 

proposed source for the 1-year period 

preceding receipt of the application. 

Where data may already exist to 

represent existing air quality, it may be 

used by the applicant; otherwise, the 

source owner or operator is responsible 

for the installation and operation of 

monitors to collect the necessary data. 

Historically, EPA has allowed the use 

of several types of screening tools to 

facilitate implementation of the 

preconstruction review process to 

reduce the permit applicant’s burden 

and streamline the permitting process 

for de minimis circumstances. These 

tools include a significant emissions 

rate (SER), SILs, and a SMC. The SER, 

defined in tons per year (tpy) for each 

regulated pollutant, is used to determine 

whether the emissions increase from 

any proposed source or modification 

can be excluded from review on the 

grounds that the increase of any 

particular pollutant is de minimis. An 

emission increase for a particular 

pollutant that is greater than the SER 

defined in the NSR regulations for that 

pollutant is considered to be a 

significant increase. 

The SIL, expressed as an ambient 

pollutant concentration (micrograms per 

cubic meter (μg/m 3)), is used to 

determine whether the ambient impact 

of a particular pollutant (once it is 

determined to be emitted in significant 

amounts) is significant enough to 

warrant a complete source impact 

analysis involving modeling the 

collective impacts of the proposed 

project and emissions from other 

existing sources. 

The PSD regulations generally require 

each PSD applicant to collect 1 year of 

continuous air quality monitoring data 

for any pollutant determined to be 

subject to preconstruction review as part 

of complete PSD permit application. 

Using the SMC as a screening tool, 

expressed as an ambient pollutant 

concentration (μg/m3), sources may be 

able to demonstrate that the modeled air 


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2The basic monitoring exemption provision is 

part of the original monitoring requirements 

adopted in the 1980 PSD rulemaking. 45 FR 52676, 

52710, August 7, 1980. 

quality impact of emissions from the 

new source or modification, or the 

existing air quality level in the area 

where the source would construct, is 

less than the SMC, i.e., de minimis, and 

may be allowed to forego the 

preconstruction monitoring requirement 

for a particular pollutant at the 

discretion of the reviewing 

authority.2See 40 CFR 51.166(i)(5) and 

52.21(i)(5). 

When the reviewing authority reaches 

a preliminary decision to authorize 

construction of a proposed major new 

source or major modification, it must 

provide notice of the preliminary 

decision and an opportunity for 

comment by the general public, 

industry, and other persons that may be 

affected by the emissions of the 

proposed major source or major 

modification. After considering these 

comments, the reviewing authority may 

issue a final determination on the 

construction permit in accordance with 

the PSD regulations. 

B. History of Particulate Matter (PM) 

NAAQS 

1. Total Suspended Particulate (TSP) 

and PM10 NAAQS 

The EPA initially established NAAQS 

for PM in 1971, measured by the TSP 

indicator. Based on the size of the 

particles collected by the ‘‘high-volume 

sampler,’’ which at that time was the 

reference method for determining 

ambient concentrations, TSP included 

all PM up to a nominal size of 25 to 45 

micrometers. We established both 

annual and 24-hour NAAQS for TSP. 

On July 1, 1987, we revised the 

NAAQS for PM and changed the 

indicator from TSP to PM10; the latter 

indicator includes particles with a mean 

aerodynamic diameter less than or equal 

to 10 micrometers. The PM10 particles 

are the subset of inhalable particles 

small enough to penetrate to the 

thoracic region (including the 

tracheobronchial and alveolar regions) 

of the respiratory tract (referred to as 

thoracic particles). We established 

annual and 24-hour NAAQS for PM10, 

and revoked the NAAQS for TSP. (52 FR 

24634). 

2. PM2.5 NAAQS 

On July 18, 1997, we again revised the 

NAAQS for PM in several respects. 

While we determined that the NAAQS 

should continue to focus on particles 

less than or equal to 10 micrometers in 

diameter, we also determined that the 

fine and coarse fractions of PM10 should 

be considered separately. We 

established new annual and 24-hour 

NAAQS using PM2.5 (referring to 

particles with a nominal mean 

aerodynamic diameter less than or equal 

to 2.5 micrometers) as the indicator for 

fine particles. The 1997 NAAQS rule 

also modified the PM10 NAAQS for the 

purpose of regulating the coarse fraction 

of PM10 (referred to as thoracic coarse 

particles or coarse-fraction particles; 

generally including particles with a 

nominal mean aerodynamic diameter 

greater than 2.5 micrometers and less 

than or equal to 10 micrometers, or 

PM10–2.5); however, this part of the 

rulemaking was vacated during 

subsequent litigation, leaving the preexisting 1987 PM10 NAAQS in place (62 

FR 38652). 

3. Revised PM2.5 and PM10 NAAQS 

On October 17, 2006, we promulgated 

revisions to the NAAQS for PM2.5 and 

PM10 with an effective date of December 

18, 2006 (71 FR 61144). We lowered the 

24-hour NAAQS for PM2.5 from 65 μg/ 

m3 to 35 μg/m3, and retained the 

existing annual PM2.5 NAAQS of 15 μg/ 

m3. In addition, we retained the existing 

PM10 24-hour NAAQS of 150 μg/m3, and 

revoked the annual PM10 NAAQS (set at 

50 μg/m3). 

C. Implementation of NSR for PM2.5

After we established new annual and 

24-hour NAAQS based on PM2.5 as the 

indicator for fine particles in July 1997, 

we issued a guidance document titled 

‘‘Interim Implementation for the New 

Source Review Requirements for PM2.5,’’ 

John S. Seitz, Director, Office of Air 

Quality Planning and Standards, EPA, 

October 23, 1997. As noted in that 

guidance, section 165 of the Act implies 

that certain PSD requirements become 

effective for a new NAAQS upon the 

effective date of the NAAQS. Section 

165(a)(1) of the Act provides that no 

new or modified major source may be 

constructed without a PSD permit that 

meets all of the section 165(a) 

requirements with respect to the 

regulated pollutant. Moreover, section 

165(a)(3) provides that the emissions 

from any such source may not cause or 

contribute to a violation of any 

increment or NAAQS. Also, section 

165(a)(4) requires BACT for each 

pollutant subject to PSD regulation. The 

1997 guidance stated that sources would 

be allowed to use implementation of a 

PM10 program as a surrogate for meeting 

PM2.5 NSR requirements until certain 

difficulties were resolved. These 

difficulties included the lack of 

necessary tools to calculate the 

emissions of PM2.5 and related 

precursors, the lack of adequate 

modeling techniques to project ambient 

impacts, and the lack of PM2.5

monitoring sites. 

On April 5, 2005, we issued a 

guidance document entitled 

‘‘Implementation of New Source Review 

Requirements in PM–2.5 Nonattainment 

Areas,’’ Stephen D. Page, Director, Office 

of Air Quality Planning and Standards, 

EPA. This memorandum provided 

guidance on the implementation of the 

nonattainment major NSR provisions in 

PM2.5 nonattainment areas in the 

interim period between the effective 

date of the PM2.5 NAAQS designations 

(April 5, 2005) and when we promulgate 

regulations to implement nonattainment 

major NSR for the PM2.5 NAAQS. In 

addition to affirming the continued use 

of the John S. Seitz guidance memo in 

PM2.5 attainment areas, this memo 

recommended that, until we 

promulgated the PM2.5 major NSR 

regulations, states should use a PM10

nonattainment major NSR program as a 

surrogate to address the requirements of 

nonattainment major NSR for the PM2.5

NAAQS. 

On November 1, 2005, we proposed a 

rule to implement the PM2.5 NAAQS, 

including proposed revisions to the NSR 

program. For those states with EPAapproved PSD programs, we proposed 

to continue the 1997 NSR guidance to 

use PM10 as a surrogate for PM2.5, but 

only during the SIP development 

period. We also indicated in that 

proposal that we would be developing 

increments, SILs, and an SMC in a 

separate rulemaking, i.e., this final rule. 

Since there was an interim surrogate 

NSR program in place, i.e., the PM10

Surrogate Policy, EPA decided to first 

promulgate the non-NSR part of the 

implementation rule (including 

attainment demonstrations, 

designations, control measures, etc.). 

This rule was promulgated as the 

CAFPIR on April 25, 2007 (72 FR 

20586). 

The NSR part of the implementation 

rule was issued separately as a final rule 

on May 16, 2008 (73 FR 28321), and 

included sets of NSR regulations for 

both attainment (PSD) and 

nonattainment areas (nonattainment 

NSR) for PM2.5. In the May 16, 2008 rule 

we added one of the important 

screening tools—the SER—for PM2.5. 

The SER for PM2.5 is defined as an 

emissions rate of 10 tpy for direct PM2.5

emissions. We also listed sulfur dioxide 

(SO2) and nitrogen oxides (NOX) as 

precursors of ambient PM2.5 and defined 

‘‘significant’’ as 40 tpy or more of either 

precursor pollutant. States were allowed 

up to 3 years from the date of 

publication in the Federal Register to 


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3Baseline dates are pollutant specific. That is, a 

complete PSD application establishes the baseline 

date only for those regulated NSR pollutants that 

are projected to be emitted in significant amounts 

(as defined in the regulations) by the applicant’s 

new source or modification. Thus, an area may have 

different baseline dates for different pollutants. 

revise their SIPs and submit their 

revised NSR programs to EPA for 

approval. 

D. Increments Under the PSD Program 

Under section 165(a)(3) of the Act, a 

PSD permit applicant must demonstrate 

that emissions from the proposed 

construction and operation of a facility 

‘‘will not cause, or contribute to, air 

pollution in excess of any (A) maximum 

allowable increase or maximum 

allowable concentration for any 

pollutant * * *.’’ The ‘‘maximum 

allowable increase’’ of an air pollutant 

that is allowed to occur above the 

applicable baseline concentration for 

that pollutant is known as the PSD 

increment. By establishing the 

maximum allowable level of ambient 

pollutant concentration increase in a 

particular area, an increment defines 

‘‘significant deterioration’’ of air quality 

in that area. 

For PSD baseline purposes, a baseline 

area for a particular pollutant emitted 

from a source includes the attainment or 

unclassifiable area in which the source 

is located, as well as any other 

attainment or unclassifiable area in 

which the source’s emissions of that 

pollutant are projected (by air quality 

modeling) to result in a significant 

ambient pollutant increase. See, e.g., 40 

CFR 52.21(b)(15)(i). Once the baseline 

area is established, subsequent PSD 

sources locating in that area need to 

consider that a portion of the available 

increment may have already been 

consumed by previous emissions 

increases. 

In general, the submittal date of the 

first complete PSD permit application in 

a particular area is the operative 

‘‘baseline date.’’ 3 On or before the date 

of the first complete PSD application, 

emissions generally are considered to be 

part of the baseline concentration, 

except for certain emissions from major 

stationary sources, as explained in the 

following discussion of baseline dates. 

Most emissions increases that occur 

after the baseline date will be counted 

toward the amount of increment 

consumed. Similarly, emissions 

decreases after the baseline date restore 

or expand the amount of increment that 

is available. 

In practice, three dates related to the 

PSD baseline concept are important in 

understanding how to calculate the 

amount of increment consumed— 

(1) Trigger date; (2) major source 

baseline date; and (3) minor source 

baseline date. The first relevant date is 

the trigger date. The trigger date, as the 

name implies, triggers the overall 

increment consumption process 

nationwide. Specifically, this is a fixed 

date, which must occur before the minor 

source baseline date can be established 

for the pollutant-specific increment in a 

particular attainment area. See, 40 CFR 

51.166(b)(14)(ii) and 52.21(b)(14)(ii). For 

PM (regulated as TSP) and SO2, 

Congress defined the applicable trigger 

date as August 7, 1977—the date of the 

1977 amendments to the Act when the 

original statutory increments were 

established by Congress. For nitrogen 

dioxide (NO2), we selected the trigger 

date as February 8, 1988—the date on 

which we proposed increments for NO2. 

See 53 FR 40656, 40658; October 17, 

1988. In this final rule, as described 

later, we are establishing a separate 

trigger date for purposes of 

implementing the PM2.5 increments. See 

section V.F of this preamble for 

additional discussion of the trigger date 

for PM2.5. 

The two remaining dates—‘‘minor 

source baseline date’’ and ‘‘major source 

baseline date’’—as described later, are 

necessary to properly account for the 

emissions that are to be counted toward 

the amount of increment consumed 

following the national trigger date, in 

accordance with the statutory definition 

of ‘‘baseline concentration’’ in section 

169(4) of the Act. The statutory 

definition provides that the baseline 

concentration of a pollutant for a 

particular baseline area is generally the 

air quality at the time of the first 

application for a PSD permit in the area. 

Consequently, any increases in actual 

emissions occurring after that date (with 

some possible exceptions that we will 

discuss later) would be considered to 

consume the applicable PSD increment. 

However, the statutory definition in 

section 169(4) also provides that 

‘‘[e]missions of sulfur oxides and 

particulate matter from any major 

emitting facility on which construction 

commenced after January 6, 1975, shall 

not be included in the baseline and 

shall be counted in pollutant 

concentrations established under this 

part.’’ 

To make this distinction between the 

date when emissions resulting from the 

construction at a major stationary source 

consume the increment and the date 

when emissions changes in general (i.e., 

from both major and minor sources) 

begin to consume the increment, we 

established the terms ‘‘major source 

baseline date’’ and ‘‘minor source 

baseline date,’’ respectively. See 40 CFR 

51.166(b)(14) and 52.21(b)(14). 

Accordingly, the ‘‘major source baseline 

date,’’ which precedes the trigger date, is 

the date after which actual emissions 

increases associated with construction 

at any major stationary source consume 

the PSD increment. In accordance with 

the statutory definition of ‘‘baseline 

concentration,’’ the PSD regulations 

define a fixed date to represent the 

major source baseline date for each 

pollutant for which an increment exists. 

Congress defined the major source 

baseline date for the statutory 

increments for PM and SO2 as January 

6, 1975. For the NO2 increments, which 

we promulgated in 1988 under our 

authority to establish an increment 

system under section 166(a) of the Act, 

the major source baseline date we 

selected was February 8, 1988—the date 

on which we proposed increments for 

NO2. 53 FR 40656. In both instances, the 

major source baseline date for the 

individual increments was set as a date 

which preceded the date on which the 

regulations pertaining to those 

increments were issued. In this final 

rule, as described later, we are 

establishing a separate major source 

baseline date for implementing the 

PM2.5 increments. See section V.F of this 

preamble for further discussion of the 

major source baseline date for PM2.5. 

The ‘‘minor source baseline date’’ is 

the earliest date after the trigger date on 

which a source or modification submits 

the first complete application for a PSD 

permit in a particular area. After the 

minor source baseline date, any increase 

in actual emissions (from both major 

and minor sources) consumes the PSD 

increment for that area. 

Once the minor source baseline date 

is established, the new emissions 

increase from that major source 

consumes a portion of the increment in 

that area, as do any subsequent actual 

emissions increases that occur from any 

new or existing source in the area. 

When the maximum pollutant 

concentration increase defined by the 

increment has been reached, additional 

PSD permits cannot be issued until 

sufficient amounts of the increment are 

‘‘freed up’’ via emissions reductions that 

may occur voluntarily, (e.g., via source 

shutdowns) or by mandatory control 

requirements imposed by the reviewing 

authority. Moreover, the air quality in a 

region cannot deteriorate to a level in 

excess of the applicable NAAQS, even 

if all the increment in the area has not 

been consumed. Therefore, new or 

modified sources located in areas where 

the air pollutant concentrations are near 

the level allowed by the NAAQS may 

not have full use of the amount of 


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4See EPA’s ‘‘Guideline on Air Quality Models’’ at 

40 CFR part 51, Appendix W. 

pollutant concentration increase 

allowed by the increment. 

Under EPA guidance, the actual 

increment analysis that a proposed new 

or modified source undergoing PSD 

review must complete depends on the 

area impacted by the source’s new 

emissions. We have provided approved 

air quality models and guidelines for 

sources to use to project the air quality 

impact of each pollutant (over each 

averaging period) for which an 

increment analysis must be done.4 In 

addition, we established SILs for each 

pollutant under the permit requirements 

applicable to new and modified major 

stationary sources locating in attainment 

areas that would cause or contribute to 

a violation of any NAAQS. See 40 CFR 

51.165(b) and part 51, Appendix S, 

section III.A. These SILs have also been 

used for implementing the PSD program 

to identify levels below which the 

source’s modeled impact of a particular 

pollutant is regarded as de minimis. In 

this final rule, we are establishing SILs 

(24-hour and annual) for PM2.5 that are 

being added to the aforementioned 

regulations containing SILs for other 

pollutants, as well as to the PSD 

regulations in 40 CFR 51.166 and 52.21. 

See further discussion of the SILs for 

PM2.5 in section VI of this preamble. 

In the event that a source’s modeled 

impacts of a particular pollutant are 

below the applicable SIL at all ambient 

air locations modeled, i.e., de minimis 

everywhere, EPA’s policy for PSD 

provides that no further modeling 

analysis is required for that pollutant. 

Our longstanding policy under the PSD 

program is that when a preliminary 

screening analysis based on the SIL is 

sufficient to demonstrate that the 

source’s emissions throughout the area 

modeled will not cause or contribute to 

a violation of the increment, there is no 

need for a comprehensive source impact 

analysis involving a cumulative 

evaluation of the emissions from the 

proposed source and other sources 

affecting the area. 

Within the impact area of a source 

subject to PSD, that is, the area within 

which the proposed project’s emissions 

increase does have a significant impact, 

increment consumption is calculated 

using the source’s proposed emissions 

increase, along with other actual 

emissions increases or decreases of the 

particular pollutant from any sources in 

the area, which have occurred since the 

minor source baseline date established 

for that area. In addition, the emissions 

increases or decreases from any major 

source that has commenced 

construction since the major source 

baseline date (which precedes the minor 

source baseline date) will consume or 

expand increment. Thus, an emissions 

inventory of sources whose emissions, 

in whole or in part, of a particular 

pollutant consume or expand the 

available increment in the area must be 

compiled. The inventory of incrementconsuming emissions includes not only 

sources located directly in the impact 

area, but sources outside the impact area 

that affect the air quality for the 

particular pollutant within the impact 

area. 

The inventory of incrementconsuming emissions includes 

emissions from increment-affecting 

sources at two separate time periods— 

the baseline date and the current period 

of time. For each source that was in 

existence on the relevant baseline date 

(major source or minor source), the 

inventory includes the source’s actual 

emissions on the baseline date and its 

current actual emissions. The change in 

emissions over these time periods 

represents the emissions that consume 

increment (or, if emissions have gone 

down, expand the available increment). 

For sources constructed since the 

relevant baseline date, all their current 

actual emissions consume increment 

and are included in the inventory. 

When the inventory of incrementconsuming emissions has been 

compiled, computer modeling is used to 

determine the change in ambient 

concentration that will result from these 

emissions when combined with the 

proposed emissions increase from the 

new major source or major modification 

that is undergoing PSD review. The 

modeling has generally been guided by 

the ‘‘Guideline on Air Quality Models’’ 

(40 CFR part 51, Appendix W), which 

includes provisions on air quality 

models and the meteorological data 

input into these models. The model 

output (expressed as a change in 

concentration) for each relevant 

averaging period is then compared to 

the corresponding allowable PSD 

increment. 

E. Historical Approaches for Developing 

Increments 

1. Congressional Enactment of 

Increments for PM and SO2

Congress established the first 

increments defining significant 

deterioration of air quality in the 1977 

Amendments to the Act. These 

amendments, among other things, added 

part C to title I, setting out the 

requirements for PSD. In section 163, 

Congress included numerical 

increments for PM and SO2 for Class I, 

II, and III areas. 

The three area classes are part of the 

increment system originally established 

by Congress. Congress designated Class 

I areas (including certain national parks 

and wilderness areas) as areas of special 

national concern, where the need to 

prevent deterioration of air quality is the 

greatest. Consequently, the allowable 

level of incremental change is the 

smallest relative to the other area 

classes, i.e., most stringent, in Class I 

areas. The increments of Class II areas 

are larger than those of Class I areas and 

allow for a moderate degree of 

emissions growth. For future 

redesignation purposes, Congress 

defined a ‘‘Class III’’ classification to 

allow the redesignation of any existing 

Class II area for which a State may 

desire to promote a higher level of 

industrial development (and emissions 

growth). Thus, Class III areas are 

allowed to have the greatest amount of 

pollutant increase of the three area 

classes while still achieving the 

NAAQS. To date, there have been no 

redesignations made to establish a Class 

III area. 

In establishing these PSD increments, 

Congress used the then-existing NAAQS 

for those pollutants as the benchmark 

for determining what constitutes 

‘‘significant deterioration.’’ Congress 

established the increments for PM as a 

percentage of the then-existing PM 

NAAQS. At the time the Act was 

amended in 1977, the NAAQS for PM 

were expressed in terms of ambient 

concentrations of TSP. Thus, EPA 

interpreted the statutory increments for 

PM using the same ambient TSP 

‘‘indicator.’’ 

2. EPA’s Promulgation of Increments for 

NO2 and PM10

Congress also provided authority for 

EPA to promulgate additional 

increments and to update the original 

PM increments created by statute. The 

EPA has promulgated two regulations 

pursuant to this authority. 

a. Increments for NO2 Using the 

‘‘Contingent Safe Harbor’’ Approach 

Under Section 166(a) of the Act 

Based on section 166(a) of the Act, on 

October 17, 1988, EPA promulgated 

increments for NO2 to prevent 

significant deterioration of air quality 

due to emissions of NOX (53 FR 40656). 

The EPA based these increments on 

percentages of the NAAQS in the same 

way that Congress derived the statutory 

increments for PM and SO2. Those NO2

increments were challenged in 1988 by 

the Environmental Defense Fund (EDF) 

when EDF filed suit in the U.S. Court of 


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5The term ‘‘air quality related values’’ is not 

defined in the Act, but the legislative history 

provides language saying that ‘‘The term ‘air quality 

related values’ of Federal lands designated as Class 

I includes the fundamental purposes for which such 

lands have been established and preserved by the 

Congress and the responsible Federal agency. For 

example, under the 1916 Organic Act to establish 

the National Park Service (16 U.S.C. 1), the purpose 

of such national park lands ‘is to conserve the 

scenery and the natural and historic objects and the 

wildlife therein and to provide for the enjoyment 

of the same in such manner and by such means as 

will leave them unimpaired for the enjoyment of 

future generations.’ ’’ S. Rep. No. 95–127 at 36 

(1977). 

6Under the 2005 NOX regulation, states can adopt 

measures other than increments as long as they can 

demonstrate that the measures selected comply 

with the same criteria and goals of sections 166(c) 

and (d) of the Act that must be met for increments. 

Appeals for the District of Columbia 

Circuit against the Administrator 

(Environmental Defense Fund, Inc. v. 

Reilly, No. 88–1882). The EDF 

successfully argued that we failed to 

sufficiently consider certain provisions 

in section 166 of the Act. The court 

remanded the case to EPA ‘‘to develop 

an interpretation of section 166 that 

considers both subsections (c) and (d), 

and if necessary to take new evidence 

and modify the regulations.’’ See 

Environmental Defense Fund v. EPA, 

898 F.2d 183, 190 (D.C. Cir. 1990) (EDF 

v. EPA). Section 166(c) of the Act 

requires the PSD regulations to, among 

other things, meet the goals and 

purposes set forth in sections 101 and 

160 of the Act. Section 166(d) requires 

these regulations be at least as effective 

as the increments established for PM (in 

the form of TSP) and SO2 in section 163 

of the Act. The court considered the 

NO2 increment values determined using 

the percentage-of-NAAQS approach as 

‘‘safe harbor’’ increments which met the 

requirements of section 166(d) of the 

Act. However, the court also determined 

that EPA’s reliance on such increment 

levels was contingent upon our 

completing the analyses required under 

section 166(c), which provided that the 

final increment values must address the 

goals of sections 101 and 160 of the Act 

to protect public health and welfare, 

parks, and AQRVs 5 and to insure 

economic growth. 

In response to the court’s decision, we 

proposed rulemaking on increments for 

NO2 on February 23, 2005 (70 FR 8880) 

and finalized the rule on October 12, 

2005 (70 FR 59582). In the final rule, we 

established our policy on how to 

interpret and apply the requirements of 

sections 166(c) and (d) of the Act. In 

accordance with the court ruling, we 

conducted further analyses (considering 

the health and welfare effects of NOX) 

and concluded that the existing NO2

increments were adequate to fulfill the 

requirements of section 166(c). See 70 

FR 59586 for our detailed analysis of 

how pollutant regulations satisfy the 

requirements of section 166 of the Act. 

Hence, we retained the existing NO2

increments along with other parts of the 

existing framework of pollutant-specific 

NO2 increment regulations. We also 

amended the PSD regulations under 40 

CFR 51.166 to make it clear that states 

may seek EPA approval of SIPs that 

utilize a different approach than EPA 

used to establish these NO2 increments. 

To receive our approval of an alternative 

program, a State must demonstrate that 

its program satisfies the requirements of 

sections 166(c) and 166(d) of the Act 

and prevents significant deterioration of 

air quality from emissions of NOX.6

b. Increments for PM10 Using 

‘‘Equivalent Substitution’’ Approach 

Under Section 166(f) of the Act 

On October 5, 1989, we proposed 

PM10 increments. See 54 FR 41218. 

Although section 163 did not expressly 

define the existing statutory increments 

for PM in terms of a specific indicator, 

EPA reasoned that Congress’ knowledge 

that TSP was the indicator for the PM 

NAAQS, and that the TSP standards 

were the starting point for the 

increments levels when the increments 

were established in 1977, meant that 

TSP was also the appropriate measure 

for the PM increments in section 163. 

As a consequence, EPA believed that the 

statutory PM increments could not 

simply be administratively redefined as 

PM10 increments, retaining the same 

numerical values, following the revision 

of the PM NAAQS. Rather, we stated 

our belief that with the promulgation of 

the PM10 NAAQS, EPA had both the 

responsibility and the authority under 

sections 166 and 301 of the Act to 

promulgate new increments for PM to 

be measured in terms of PM10. We 

further concluded that promulgating 

PM10 increments to replace, rather than 

supplement, the statutory TSP 

increments under section 163 

represented the most sensible approach 

for preventing significant deterioration 

with respect to PM. See 54 FR 41220– 

41221. 

We promulgated PM10 increments to 

replace the then-existing TSP 

increments on June 3, 1993 (58 FR 

31622). In the interim between proposal 

and promulgation, Congress enacted the 

1990 CAA Amendments. As part of 

these amendments, Congress amended 

section 166 to add a new section 166(f). 

This section specifically authorized EPA 

to substitute PM10 increments for the 

existing section 163 PM increments 

based on TSP, provided that the 

substituted increments are ‘‘of equal 

stringency in effect’’ as the section 163 

increments. 

Thus, we were able to replace the TSP 

increments under section 163 of the Act 

using PM10 increments based directly on 

the newly enacted authority under 

section 166(f) of the Act. In the PM10

rule, we maintained the existing 

baseline dates and baseline areas for PM 

that had been previously established 

using the TSP indicator. Also, as 

proposed, we promulgated PM10

increments based on an approach we 

called the ‘‘equivalent to statutory 

increments’’ approach. Under this 

approach, we used the original TSP 

increments as a benchmark for 

calculating the PM10 increments, 

thereby retaining roughly the same 

limitations on future deterioration of air 

quality as was allowed under the TSP 

increments. 

In using this approach, we considered 

the historical consumption of TSP 

increment by a sample population of 

permitted PSD sources, and then 

determined the PM10 increments for 

each area classification and averaging 

time that would provide approximately 

the same percentage of PM10 increment 

consumption, on average, by the same 

population of sources. Then, all future 

calculations of increment consumption 

after the PM10 implementation date 

would be based on PM10 emissions. See 

58 FR 31622 and 31625. 

V. Final Action on PM2.5 Increments 

In this section of the preamble, we 

will summarize the considerations that 

went into our proposed action and 

describe the final action being taken 

regarding new regulations for 

preventing significant deterioration of 

PM2.5 air quality—including PM2.5

increments (sections V.A through V.E, 

baseline dates and other permit 

requirements for PM2.5 (section V.F), 

baseline areas for PM2.5 (section V.G), 

and PM10 increments (section V.H). 

A. Decision To Establish PM2.5

Increments Using ‘‘Contingent Safe 

Harbor Approach’’ Under Section 166(a) 

The EPA’s 2007 NPRM contained 

three options for developing numerical 

PM2.5 increments. Option 1 used the 

authority of section 166(a) of the Act to 

establish increments for PM2.5 as a new 

pollutant for which NAAQS were 

established after August 7, 1977, and 

established 24-hour and annual PM2.5

increments (Class I, II, and III) based on 

the ‘‘contingent safe harbor’’ approach. 

Options 2 and 3 used the contingent 

safe harbor approach under section 

166(a) to only develop 24-hour PM2.5

increments (Class I, II, and III), while 

using the ‘‘equivalent substitution’’ 


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approach under section 166(f) of the Act 

to develop annual PM2.5 increments. 

Each of these options is discussed in 

detail in the 2007 NPRM. 72 FR 54123– 

54138. In addition, significant 

comments on each of the three options, 

and our responses to them, are provided 

in this section V of this preamble. 

In this final rule, after considering the 

available information and comments 

from interested parties, EPA has 

decided to select Option 1 and establish 

increments for PM2.5 using the 

‘‘contingent safe harbor’’ approach in 

accordance with the authority provided 

in section 166(a) of the Act. 

This final rule establishes increments 

for PM2.5 at the following levels: 

Averaging period NAAQS 

(μg/m3) 

Increments (μg/m3) 

Class I Class II Class III 

Annual .............................................................................................................................. 15 1 4 8 

24-hour ............................................................................................................................. 35 2 9 18 

B. Rationale for the Applicability of 

Section 166(a) 

In the 2007 NPRM, we expressed our 

belief that it is permissible to interpret 

section 166(a) to apply to PM2.5. Section 

166(a) requires EPA to develop 

regulations to prevent the significant 

deterioration of air quality due to 

emissions of certain named pollutants, 

and to develop such regulations for any 

pollutants for which NAAQS are 

subsequently promulgated. Although 

EPA has generally characterized the 

NAAQS for PM2.5 as a NAAQS for a new 

indicator of PM, EPA did not replace the 

PM10 NAAQS with the NAAQS for 

PM2.5 when the latter NAAQS were 

promulgated in 1997. Rather, EPA 

retained the annual and 24-hour PM10

NAAQS (retaining PM10 as an indicator 

of coarse particulate matter), and 

established new annual and 24-hour 

NAAQS for PM2.5 as if PM2.5 was a new 

pollutant, even though EPA had already 

developed air quality criteria for PM 

generally. Thus, for purposes of section 

166(a), the promulgation of a NAAQS 

for PM2.5 established a NAAQS for an 

additional pollutant after 1977. 

Nine commenters supported our 

proposed Option 1, although only three 

of these explicitly expressed support for 

the use of section 166(a) authority to 

promulgate PM2.5 increments. Ten other 

commenters specifically opposed the 

use of section 166(a) authority and/or 

supported the use of section 166(f) 

authority (on which the annual 

increments under Options 2A and 2B 

were based). 

One of the commenters who explicitly 

agreed with our proposed use of section 

166(a) authority stated that it is the only 

option that is legally available. This 

commenter asserted that section 166(a) 

plainly applies to PM2.5 because PM2.5 is 

a pollutant for which NAAQS were 

promulgated after August 7, 1977. This 

commenter held that EPA’s rulemaking 

duty under section 166(a) is not 

confined to ‘‘new pollutants,’’ but is 

triggered by post-1977 NAAQS 

promulgations, regardless of whether for 

new or previously regulated pollutants. 

On the other hand, this commenter 

noted that by its terms, section 166(f) is 

limited to authorizing the adoption of 

PM10 increments as a substitute for the 

statutory TSP increments and does not 

provide for substitution of PM2.5

increments for TSP or PM10 increments. 

The opposing commenters did not 

believe that section 166(a) provides a 

legal basis for EPA to promulgate PM2.5

increments. One of these commenters 

stated that section 166(a) can only be 

used for a new pollutant, and PM2.5 is 

not a new pollutant. 

Another commenter who opposed the 

use of section 166(a) authority argued 

that nothing in section 166(a) of the Act 

can be interpreted to allow it to be used 

as the basis of increments when EPA 

revises an existing NAAQS. The 

commenter explained that, on its face, 

section 166(a) can only be interpreted to 

apply to pollutants other than PM and 

SO2 since increments for these 

pollutants were enacted by Congress in 

section 163 of the Act. The commenter 

added that it can be argued that 

Congress intended to have section 

166(a) apply to the four other pollutants 

specifically listed there. 

This commenter found unpersuasive 

our argument that we are not 

‘‘substituting’’ increments (as section 

166(f) requires for PM10) but rather 

adding PM2.5 increments to the existing 

PM10 increments, and that only section 

166(a) allows such an approach (72 FR 

54121). The commenter asserted that if 

EPA had defined a coarse fraction to the 

particulate matter standards, then that 

fraction, together with the PM2.5

standards, would form the set of 

‘‘substituted’’ new standards for the 

existing PM10 standards, and, thus, the 

increments. 

The commenter also disagreed with 

EPA’s argument that it can treat PM2.5 as 

a new pollutant under section 166(a) of 

the Act since it has been demonstrated 

that sub-PM2.5 particles have distinctly 

different health and welfare effects than 

the other forms of PM (i.e., coarse or 

PM10). The commenter indicated that 

just as EPA replaced the TSP standards 

by PM10 as a better indicator of health 

effects, ongoing research has led to 

establishment of the PM2.5 standards as 

a better indicator of certain health 

effects, and it is the natural outcome of 

such research that has enabled EPA to 

separate the effect of total particulate 

matter into two fractions with distinct 

effects. The commenter added that given 

that the definition of particulate matter 

includes a vast conglomeration of solids 

and liquids, the finding of differing 

effects should not come as a surprise. 

The commenter explained that as is the 

case of different pollutants having 

similar effects that are, nonetheless, 

treated as separate pollutants, the same 

concept should apply to a range or 

fraction of particulate matter found to 

have different effects in establishing it 

as another indicator and not a different 

pollutant. 

The commenter did not disagree with 

the specific numerical increments 

proposed by EPA under Option 1, but 

did have concerns with the potential 

consequences of the section 166(a) 

approach. The commenter’s primary 

concern was the proposal to allow states 

to substitute other measures in the place 

of uniform national increments for 

PM2.5. (This is discussed further in 

section V.C.5 of this preamble.) Another 

commenter also expressed this concern. 

Another commenter who opposed the 

section 166(a) approach believes that 

the legal and congressional history 

regarding the establishment of PM 

increments shows that Congress added 

section 166(f) to the Act based on the 

conviction that without it, EPA had no 

authority to revise the PM increments 

for PM10 (citing and quoting from S. 

Rep. No. 228, 101st Cong., 2nd Sess. 75 

(1990), reprinted in 1990 U.S.C.C.A.N. 

3385, 3461). The commenter concluded 

that EPA did not have authority in 1987 

under section 166(a) to adopt PM10

increments, and does not have authority 

now under section 166(a) to adopt PM2.5

increments. 

We read section 166(a) to authorize 

EPA to promulgate pollutant-specific 

PSD regulations meeting the 


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7We also believe that we sufficiently described 

how section 166(f) might provide alternative 

authority for establishing increments for PM2.5 (see, 

e.g., 72 FR 54120–54121), but will not address that 

in detail here because the increments in this rule 

are not based on section 166(f) authority. 

requirements of sections 166(c) and 

166(d) for any pollutant for which EPA 

promulgates a NAAQS after 1977. Most 

of the pollutants identified in section 

166(a) (NOX, photochemical oxidants, 

carbon monoxide) are pollutants for 

which EPA had established NAAQS in 

1977 when Congress adopted section 

166 of the Act. There was no need for 

Congress to list other criteria pollutants, 

SO2 and PM, in section 166(a) because 

Congress had already established 

increments for these pollutants in 

section 163 of the Act. In addition to 

requiring regulations for the enumerated 

pollutants, we conclude that under 

section 166 of the Act Congress 

intended to authorize EPA to establish 

additional pollutant-specific PSD 

regulations, potentially containing 

increments, for any additional 

pollutants for which EPA promulgated a 

NAAQS under section 109 of the Act. 

Furthermore, because the Act refers to 

pollutants for which EPA promulgates 

NAAQS after 1977, and does not use the 

phrase ‘‘additional pollutants,’’ section 

166(a) provides authority for EPA to 

promulgate new increments after 

revising an existing NAAQS (including 

NAAQS first promulgated before 1977), 

when we find that such action is 

appropriate. 

Moreover, any new increments 

developed pursuant to section 166(a) 

have no effect on existing increments, as 

there is no indication therein that an 

existing increment should be revoked or 

replaced when additional increments 

are promulgated. This was the situation 

following the promulgation of new 

NAAQS for PM in 1987 when EPA 

replaced the old NAAQS based on TSP 

with new ones based on PM10. Had 

Congress not added new section 166(f) 

in 1990, increments for PM10 could have 

been developed pursuant to section 

166(a) of the Act, but such increments 

would have had no effect on the original 

statutory increments for PM (based on 

TSP). Consequently, seeing no basis for 

retaining the original increments, 

Congress added section 166(f) which 

explicitly provides for the replacement 

of the existing increments with PM10

increments. 

One commenter asserted that if EPA 

establishes increments for PM2.5 under 

the authority of section 166(a) on the 

basis that PM2.5 is a new pollutant, then 

it must also establish PM10 increments 

under section 166(a) because (according 

to the commenter’s analysis) PM10 is 

also a new pollutant. In the same 

analysis, the commenter concluded that 

EPA must adopt new measures to 

prevent significant deterioration from 

coarse PM based on section 166(a). 

In this final rule, EPA is not setting or 

amending any increments for PM10 or 

otherwise taking action with respect to 

PM10 increments. The preexisting 

annual and 24-hour increments for PM10

are being retained. See section V.H. 

Similarly, EPA is not taking any action 

with respect to coarse PM in this rule. 

For these reasons, the commenter’s 

arguments on what authority must be 

used to set increments for PM10 and/or 

coarse PM, and that EPA has some 

obligation to take action with respect to 

coarse PM, are not on point for this rule. 

Thus, no substantive response to this 

comment is needed. Nevertheless, as 

mentioned earlier, Congress provided 

explicit authority under section 166(f) of 

the Act to address increments for PM10,

because it intended for such increments 

to be substitute increments for the 

original statutory increments for PM 

measured as TSP. Thus, the PM10

increments legally supersede the 

original statutory increments for PM. 

Had the PM10 increments been 

developed under section 166(a), which 

prior to the 1990 Act Amendments was 

the only authority available for 

developing new increments, then the 

original statutory PM increments would 

have remained in effect in addition to 

the PM10 increments. 

One commenter expressed general 

objections to EPA’s legal rationale for 

the PM2.5 increments proposal, asserting 

that we failed to expressly state and 

support our legal authority for the PM2.5

increments, offering two possible 

sources of authority (‘‘contingent safe 

harbor,’’ ‘‘equivalent substitution,’’ or 

possibly a combination of the two) but 

never stating our legal position with 

clarity. The commenter agreed with 

EPA’s assessment that the PM2.5

increments should and must fulfill the 

legal requirements of the Act (72 FR 

54121), and added that it is the 

government’s burden of proof to 

establish its legal authority for action. 

The commenter stated that it would be 

arbitrary and capricious to promulgate 

these regulations for which EPA has not 

stated legal authority. 

We do not disagree that the 2007 

NPRM described two different legal 

authorities for the two different options 

for establishing increments, but we 

disagree that these discussions did not 

clearly present the alternative legal 

bases that the Agency was considering 

for taking action in this rule. In 

particular, we clearly described our 

legal authority for developing the 24- 

hour and annual PM2.5 increments 

under section 166(a) of the Act, which 

is the basis on which we are taking final 

action in this rule.7 First, we expressly 

stated that Option 1 was based on the 

statutory authority of section 166(a) of 

the Act. See 72 FR 54123 (Under the 

first option, ‘‘we would use the authority 

of section 166(a) of the Act to develop 

new increments for PM2.5’’). Second, we 

provided a discussion of this authority 

both in general (see 72 FR 54118–54119 

and 54120–54123), and how it would be 

applied to establish increments for 

PM2.5 (see 72 FR 54119–120 and 54123– 

136). 

We now believe that section 166(a) 

provides the most straightforward 

approach for developing increments for 

a pollutant or pollutant indicator for 

which no increments have yet been 

established. Our position is also 

consistent with the comments we 

received which supported the delay in 

implementation of the PM2.5

increments, opposed the potential for 

two sets of definitions for ‘‘major source 

baseline date’’ and ‘‘trigger date’’ for the 

PM2.5 increment system, and 

highlighted the complexities involved 

with having to establish and maintain 

two sets of emissions inventories for the 

24-hour and annual PM2.5 increments. 

(See further description of relevant 

comments in section VIII of this 

section.) 

C. EPA’s Interpretation of the 

Requirements Under Sections 166(a)–(d) 

of the Act 

In section 166(a) of the Act, Congress 

directed EPA to develop pollutantspecific regulations to prevent 

significant deterioration of air quality. 

Congress further specified that such 

regulations meet specific requirements 

set forth in sections 166(c) and 166(d) of 

the Act. We stated in the 2007 NPRM 

that because we believed that section 

166(a) could be applied to the 

development of increments for PM2.5, 

we would follow the interpretation of 

sections 166(a)–(d) that the Agency 

adopted in its most recent NO2

increments rule. 70 FR 59582, October 

12, 2005. That particular interpretation 

and application was upheld in 

Environmental Defense v. EPA, 489 F.3d 

1320 (D.C. Cir. 2007). 

The EPA’s interpretation of these 

provisions is grounded on five 

principles and conclusions. First, we 

read section 166 of the Act to direct EPA 

to conduct a holistic analysis that 

considers how a complete system of 

regulations will collectively satisfy the 


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applicable criteria, rather than 

evaluating one individual part of a 

regulatory scheme in isolation. Second, 

we use a ‘‘contingent safe harbor’’ 

approach which calls for EPA to first 

determine an increment that is at least 

as effective as the increments in section 

163 of the Act, as required under section 

166(d) and then to conduct further 

analysis to determine if additional 

measures are necessary to fulfill the 

requirements of section 166(c). Third, 

we interpret section 166(c) of the Act to 

identify eight statutory factors that EPA 

must apply when promulgating 

pollutant-specific regulations to prevent 

significant deterioration of air quality. 

Fourth, where these factors are at odds 

with each other, we interpret the statute 

to require EPA to use its judgment to 

balance the conflicting factors. Fifth, we 

recognize that the requirements of 

section 166 may be satisfied by adopting 

other measures besides an increment 

and that EPA may allow states to 

demonstrate that alternatives to 

increments contained in a SIP meet the 

requirements of sections 166(c) and 

166(d). Below is a brief discussion of 

each of these five principles and 

conclusions. A more detailed 

description of each of these is contained 

in the 2007 NPRM at 72 FR 54121– 

54123. 

1. Regulations as a Whole Should Fulfill 

Statutory Requirements 

Section 166(a) of the Act directs EPA 

to develop pollutant-specific regulations 

to prevent the significant deterioration 

of air quality. Sections 166(c) and 166(d) 

provide detail on the contents of those 

regulations, but do not necessarily 

require the same type of increment 

system Congress created in section 163 

of the Act. The EPA interprets section 

166 to require that the entire system of 

PSD regulations (the framework and 

details, as described in section V.D of 

this preamble) for a particular pollutant 

must, as a whole, satisfy the criteria in 

sections 166(c) and 166(d) of the Act. 

2. Contingent Safe Harbor Approach 

Section 166(c) of the Act describes the 

kinds of measures to be contained in the 

regulations to prevent significant 

deterioration of air quality called for in 

section 166(a) and specifies that these 

regulations are to ‘‘fulfill the goals and 

purposes’’ set forth in sections 160 and 

101 of the Act. Section 166(d) of the Act 

directs EPA to ‘‘fulfill such goals and 

purposes’’ by providing ‘‘specific 

measures at least as effective as the 

increments established in section 163 

* * *.’’ Thus, EPA reads section 166(d) 

to require that the Agency identify ‘‘safe 

harbor’’ pollutant-specific PSD 

regulations adopted under section 166. 

The EPA reads section 166(c) to 

require that the Agency conduct further 

review to determine whether, based on 

the criteria in section 166(c), EPA’s 

pollutant-specific PSD regulations 

under section 166 should contain 

measures that are different from the 

‘‘safe harbor’’ identified under section 

166(d). The EPA construes section 

166(d) to require that the measures be 

‘‘at least as effective’’ as the statutory 

increments set forth in section 163. 

To apply the ‘‘contingent safe harbor’’ 

approach for PM2.5, we first identified 

‘‘safe harbor’’ increments for each area 

classification (Class I, II, or III), using: 

(1) Equivalent percentages of the 

NAAQS as the percentages used for 

developing the statutory increments; (2) 

the same pollutant as the NAAQS, i.e., 

PM2.5, and (3) the same time (averaging) 

periods as were used for the PM2.5

NAAQS. We concluded that this 

approach would ensure that the 

increments would be ‘‘at least as 

effective as the increments established 

in section 163,’’ as required by section 

166(d). Second, EPA conducted further 

review to determine whether the ‘‘safe 

harbor’’ increments, in conjunction with 

existing elements of the PSD program or 

additional measures proposed under 

section 166 to augment the increments, 

sufficiently fulfill the criteria in 

subsection (c) of section 166. 

In this review, we weighed and 

balanced the criteria set forth in 

subsection (c) (and, as provided in 

subsection (c), the incorporated goals 

and purposes of the Act in section 101 

and the PSD program in section 160) to 

determine whether additional measures 

might be needed to satisfy the criteria in 

subsection (c). See section V.E.6 of this 

preamble for further discussion of our 

evaluation, comments on the evaluation, 

and our response to them. 

3. The Statutory Factors Applicable 

Under Section 166(c) 

The EPA interprets section 166(c) of 

the Act to establish eight factors to be 

considered in the development of PSD 

regulations for the pollutants covered by 

this provision. These eight factors 

included the three criteria stated in 

section 166(c) and the five goals and 

purposes identified in section 160 of the 

Act (which, as noted below, also cover 

the goals and purposes set forth in 

section 101). The three stated criteria in 

section 166(c) indicate that PSD 

regulations for specific pollutants 

should provide: (1) Specific numerical 

measures for evaluating permit 

applications; (2) a framework for 

stimulating improved control 

technology, and (3) protection of air 

quality values. The five goals and 

purposes in section 160 are 

incorporated into the analysis by virtue 

of the fourth criterion in section 166(c), 

which directs that EPA’s pollutantspecific PSD regulations ‘‘fulfill the 

goals and purposes’’ set forth in sections 

160 and 101 of the Act. We construed 

the term ‘‘fulfill the goals and purposes,’’ 

as used in section 166(c), to mean that 

EPA should apply the goals and 

purposes listed in section 160 as factors 

applicable to pollutant-specific PSD 

regulations established under section 

166. The Agency’s view is that PSD 

measures that satisfy the specific goals 

and purposes of section 160 also satisfy 

the more general purposes and goals 

identified in section 101 of the Act. See 

72 FR 54122. 

One commenter disagreed with our 

interpretation that the goals and 

purposes of section 160 also satisfy all 

of those in section 101. This commenter 

asserted that although there is some 

overlap between the two sections, they 

are not identical. As an example, the 

commenter noted that section 101 

expressly states that a primary goal of 

the Act is to promote pollution 

prevention—a goal not stated in section 

160. The commenter asserted that, 

although the proposed increments 

would limit some pollution increases, 

there was no provision in the proposal 

that would require or promote pollution 

prevention. 

We disagree with the commenter and 

continue to believe that measures that 

satisfy the specific goals and purposes 

of section 160 also satisfy the more 

general purposes and goals identified in 

section 101 of the Act. As we stated in 

the 2005 NO2 increment rulemaking, the 

overall goals and purposes of the Act 

listed in sections 101(b) and 101(c) are 

general goals regarding protecting and 

enhancing the nation’s air resources and 

controlling and preventing pollution. 

Because these broad goals are given 

more specific meaning in section 160, 

EPA does not believe it is necessary to 

consider them in detail when evaluating 

whether PSD regulations satisfy the 

criteria in section 166(c). 70 FR 59587 

FN 3. 

Regarding pollution prevention 

specifically, we believe that this general 

goal is encompassed in, and given more 

specific meaning by, sections 160(1), 

160(2), and 160(4) of the Act. These 

sections spell out the specific purposes 

under the PSD program for the general 

section 101 goals of controlling and 

preventing pollution. We believe that 

any requirement to limit or reduce 

emissions serves to promote pollution 

prevention, which is often the most cost 


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effective means of lowering pollutant 

emissions. 

In addition to citing the purposes set 

out in section 160, section 166(c) 

includes the criterion that pollutantspecific PSD regulations should provide 

a framework for stimulating improved 

control technology. As discussed 

subsequently in sections V.D.1 and 

V.D.6 of this preamble, we believe that 

this criterion is fulfilled by the system 

of increments for PM2.5 and by the 

requirement for PSD permittees to apply 

BACT to minimize PM2.5 emissions. In 

stimulating improved control 

technology generally, these elements of 

the PSD program also promote pollution 

prevention. As noted previously, 

pollution prevention is often the most 

cost effective means of control, 

particularly for new sources and new 

process lines at existing sources. In 

addition, because BACT is a case-bycase determination that considers cost 

and collateral environmental impacts, 

pollution prevention, where technically 

feasible, often fairs well in BACT 

analyses because it is typically free from 

the negative environmental impacts that 

result from the use of add-on air 

pollution control devices. 

4. Balancing the Factors Applicable 

Under Section 166(c) 

While the eight factors in section 

166(c) are generally complementary, 

there are circumstances where some of 

the objectives may be in conflict with 

each other. In these situations, some 

degree of balance or accommodation is 

inherent in the requirement to establish 

regulations that satisfy all of these 

factors. As first discussed in our 2005 

NO2 increments rulemaking (70 FR 

59582 at 59587), we believe this 

balancing test derives primarily from 

the third goal and purpose set forth in 

section 160: To insure economic growth 

consistent with the preservation of 

existing clean air resources. A more 

detailed discussion of how the 

balancing of factors should be 

interpreted is contained in the 2007 

NPRM at 72 FR 54122–54123. 

One commenter claimed that EPA 

‘‘incorrectly and repeatedly asserts’’ that 

a goal of section 160 of the Act is to 

insure economic growth. The 

commenter claimed that neither section 

160 nor section 101 of the Act uses 

language to support a goal of promoting 

or maximizing opportunities for 

economic growth. Instead, the 

commenter asserted that both sections 

state only that any growth that does 

occur must be consistent with 

protection of air quality. The commenter 

concluded that ‘‘EPA’s notion that the 

need to satisfy the other requirements of 

Section 166 and other goals and 

purposes in Sections 101 and 160 can 

never preclude additional emissions 

from economic growth unlawfully 

elevates such growth over all other 

statutory factors.’’ 

The language in section 160(3) 

provides that one of the purposes of the 

PSD program is ‘‘to insure that economic 

growth will occur in a manner 

consistent with the preservation of 

existing clean air resources.’’ The 

commenter suggests that this language 

can only be read as if the statutory 

phrase ‘‘economic growth’’ actually said 

‘‘any economic growth that does occur’’ 

such that section 160(3) says ‘‘to insure 

that any economic growth that does 

occur will occur in a manner consistent 

with the preservation of existing clean 

air resources.’’ We disagree; the phrasing 

used by Congress is ‘‘to insure that 

economic growth will occur.’’ Thus, we 

believe the plain language of the statute 

supports EPA’s reading that section 

160(3) requires a balancing of the goals 

of (1) economic growth and (2) 

preservation of existing clean air 

resources. At a minimum, if the 

language were to be considered 

ambiguous enough to allow the 

commenter’s reading, then the Agency’s 

interpretation is also a reasonable 

reading of the statutory language. 

5. Authority for States To Adopt 

Alternatives to Increments 

While section 166 of the Act 

authorizes EPA to promulgate 

increments for pollutants listed under 

section 166(a), we have also interpreted 

the section to allow states to employ 

approaches other than increments to 

prevent significant deterioration of air 

quality, so long as such an approach 

otherwise meets the requirements of 

sections 166(c) and 166(d). This 

interpretation was explained in the 2005 

NO2 increment rulemaking (70 FR 

59611–59612), in which we amended 

the PSD regulations at 40 CFR 51.166 by 

adding new paragraph (c)(2) to codify 

this statutory authority. Under the 

existing provision in 40 CFR 

51.166(c)(2), states may seek EPA 

approval of SIPs that use an alternative 

approach to increments if the State can 

demonstrate that the alternative 

program satisfies the requirements of 

sections 166(c) and 166(d). However, 

the current language at paragraph (c)(2) 

states the authority for states to adopt 

alternative measures only with respect 

to increments for NO2. To clarify our 

interpretation that the authority to adopt 

alternative measures covers any 

pollutant listed in section 166(a), we are 

revising 40 CFR 51.166(c)(2) to make it 

inclusive to all applicable pollutants 

rather than just NO2. 

Two commenters supported our 

proposal to revise paragraph (c)(2) to 

include PM2.5, while four State/local 

agency commenters expressed 

opposition. An environmental 

commenter agreed that the Act allows 

for other approaches, but believes that 

such approaches must be in addition to 

the national increments. Specifically, 

this commenter stated that ‘‘although 

EPA can provide for states to adopt 

approaches in addition to increments in 

order to fulfill the statutory purposes, 

the agency must make clear that states 

cannot adopt approaches that are less 

protective that the national increments.’’ 

This commenter further stated that ‘‘to 

the extent that EPA is suggesting that it 

can allow states to adopt PSD programs 

that do not include the minimum 

Federal increments, that position is 

contrary to the statute.’’ 

As in the 2005 NO2 increment 

rulemaking, we are codifying the basic 

principle that states can seek to use 

alternative measures without defining 

any specific type of alternative program 

that would be approved or otherwise 

creating standards beyond the 

requirements of sections 166(c) and 

166(d). Instead, we plan to make 

determinations on a case-by-case basis 

when a State submits a specific 

alternative approach for EPA to approve 

as part of a SIP. In making those 

determinations, we will address the 

specific alternative measures as states 

propose them to the Agency in light of 

the requirements of sections 166(c) and 

166(d), including whether the 

alternative program is ‘‘at least as 

effective as the increments established 

in section 163,’’ as required in section 

166(d). 

The four State/local agency 

commenters opposing the revision to 40 

CFR 51.166(c)(2) expressed the 

importance of using uniform national 

increments for PM2.5. One commenter 

argued that a nationally inconsistent 

approach to PM2.5 in attainment areas 

could result in a patchwork of State PSD 

regulations—and the exact kinds of 

economic repercussions that Congress 

wished to avoid. The same commenter 

argued that varying incrementequivalent measures could also result in 

an uneven playing field for industry and 

could exacerbate difficulties between 

states experiencing transport problems. 

Another opposing commenter was 

concerned that allowing states to adopt 

alternatives to increments would likely 

lead to a ‘‘mish-mash’’ of State 

approaches which defeats the intention 

of Congress that there be uniformity in 

PSD rules to avoid economic 


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dissimilarities from State to State that 

could allow interstate competition for 

industry based upon which State offers 

the best (least expensive) environmental 

compliance regulations. Another 

commenter objected to allowing the use 

of alternatives to increments by stating 

that such alternative allowances 

undermine the desired national 

consistency, and EPA has failed to even 

identify any Act programs which would 

benefit from this approach. 

While we acknowledge the potential 

problems identified by the commenters 

associated with allowing states to adopt 

alternative approaches to the numerical 

increments that we are establishing, we 

also note that section 166(d) expressly 

gives EPA some latitude in 

promulgating regulations that will be at 

least as effective as the increments in 

section 163, by stating that such 

regulations ‘‘may contain air quality 

increments, emission density 

requirements, or other measures.’’ Thus, 

EPA is authorized to provide that states 

may consider alternatives to the 

increments established in this rule. That 

said, the statutory authority is not a 

blank check for states to do as they 

please, but enables states to consider 

options that may provide a meaningful 

way for them to manage their air 

resources within the framework allowed 

by the statutory PSD requirements. 

D. Framework for Pollutant-Specific 

PSD Regulations for PM2.5

In the 2007 NPRM, we proposed to 

apply the same basic framework for 

pollutant-specific PSD regulations for 

PM2.5 that we used in our 2005 NO2

increments regulations. Specifically, we 

proposed adopting an increment and 

area classification system for PM2.5 and 

applying the statutory AQRV review 

process to PM2.5 as well. We also 

indicated that while some of the factors 

applicable under section 166(c) are 

fulfilled by using this type of framework 

for pollutant-specific PSD regulations 

under section 166(a) of the Act, this 

framework of regulations also needs to 

satisfy the other applicable factors. 

Thus, the details of our regulations 

(such as the characteristics of the 

increments themselves) are important, 

and we evaluated the effectiveness of 

the framework in conjunction with more 

detailed elements of our regulations. As 

discussed in the following subsections, 

we believe our obligations under section 

166(c) of the Act are satisfied when the 

PSD regulations collectively satisfy the 

factors applicable under 166(c) of the 

Act. 

1. Increment System 

An increment-based program satisfies 

the requirements under 166(c) to 

provide ‘‘specific numerical measures 

against which permit applications may 

be evaluated.’’ An increment is the 

maximum allowable level of ambient 

pollutant concentration increase that is 

allowed to occur above the applicable 

baseline concentration in a particular 

area. As such, an increment defines 

‘‘significant deterioration.’’ Establishing 

an increment system for PM2.5 will 

fulfill two of the factors applicable 

under section 166(c): (1) Providing 

specific numerical measures to evaluate 

permit applications, and (2) stimulating 

improved control technology. 

First, under section 165(a)(3) of the 

Act, a permit applicant must 

demonstrate that emissions from the 

proposed construction and operation of 

a facility ‘‘will not cause, or contribute 

to, air pollution in excess of any (A) 

maximum allowable increase or 

maximum allowable concentration for 

any pollutant * * *.’’ Once the baseline 

date associated with the application for 

the first new major stationary source or 

major modification in an area is 

established, the new emissions from 

that source consume a portion of the 

increment in that area, as do any 

subsequent emissions increases that 

occur from any source in the area. When 

the maximum pollutant concentration 

increase defined by the increment has 

been reached, additional PSD permits 

cannot be issued until sufficient 

amounts of the increment are ‘‘freed up’’ 

via emissions reductions that may be 

required by the reviewing authority. 

Thus, an increment is a quantitative 

value that establishes a ‘‘maximum 

allowable increase’’ for a particular 

pollutant. It functions, therefore, as a 

specific numerical measure that can be 

used to evaluate whether an applicant’s 

proposed project will cause or 

contribute to air pollution in excess of 

allowable levels. 

Increments also satisfy the second 

factor in section 166(c) by providing ‘‘a 

framework for stimulating improved 

control technology.’’ Increments 

establish an incentive to apply 

improved control technologies in order 

to avoid violating the increment and to 

‘‘free up’’ available increment to promote 

continued economic growth. These 

control technologies may become the 

basis of BACT determinations 

elsewhere, as the technologies become 

more commonplace and the costs tend 

to decline. 

One commenter stated that, although 

increments may encourage the use of 

existing control technologies, EPA has 

not cited any evidence that increments 

actually stimulate the development of 

improved technologies. Moreover, the 

commenter asserted that even if 

increments provide the incentive 

asserted by EPA, any encouragement of 

improved control technology is wholly 

incidental and hardly amounts to a 

‘‘framework’’ whose purpose is to 

stimulate such technology. 

We continue to believe that the total 

program, encompassing increments and 

BACT, does provide an appropriate 

framework to stimulate BACT in such a 

way that it is not simply ‘‘wholly 

incidental,’’ as the commenter claims. 

The fact that economic growth in an 

area must occur within a defined 

amount of allowable air quality 

deterioration should logically lead to 

the application of improved pollution 

control technology as the amount of 

deterioration increases, and should not 

be regarded as an incidental 

consequence. As stated in the 2007 

NPRM, Congress envisioned that the 

increments they originally established 

would serve as an incentive: ‘‘The 

incremental ceiling should serve as an 

incentive to technology, as a potential 

source may wish to push the frontiers of 

technology in a particular case to obtain 

greater productive capacity with the 

limits of the increments.’’ S. Rep. 95– 

127 at 18, 30 (3 LH at 1392, 1404). We, 

too, believe that as the available 

increment in an area becomes smaller, 

and as states try to preserve some of the 

remaining increments for future growth, 

it will be necessary to require sources to 

install more stringent controls in that 

area. Such levels of control ultimately 

must be considered in subsequent BACT 

evaluations in other PSD areas 

throughout the country. Admittedly, the 

increasing stringency of control 

technologies over time, as observed in 

EPA’s BACT/Lowest Achievable 

Emission Rate (LAER) Clearinghouse, 

supports but cannot in itself 

conclusively demonstrate that the PSD 

program has already stimulated 

development of improved control 

technology; there are undoubtedly a 

number of factors that could cause such 

trends. Nevertheless, even the need to 

require a more stringent BACT 

determination in only a few PSD areas 

(due to dwindling increment 

availability) necessitates consideration 

of that level of control for all other PSD 

sources wherever they may decide to 

locate. In any event, while the 

commenter generally questions the 

effectiveness of the increments as an 

incentive for tightening BACT, they 

provided no evidence that more 

stringent BACT is not related to the 


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increment system established as an 

integral part of the PSD program. 

2. Area Classifications 

In this final rule, EPA is establishing 

the same three-tiered area classification 

system for PM2.5 that is applicable to the 

increments for NO2 and other pollutants 

under the PSD program and the Act. 

Accordingly, areas that are currently 

Class I for other pollutants will also be 

Class I for PM2.5 and all other areas will 

be Class II for PM2.5 unless we 

redesignate the area based on a request 

by a State or tribe pursuant to the 

process in section 164 of the Act and 

EPA’s regulations at 40 CFR 51.166(g) 

and 52.21(g). 

As explained earlier in section IV.E.1, 

Class I areas are areas where very clean 

air is most desirable. In contrast, Class 

III areas are designed as those areas in 

which a State wishes to permit the 

highest relative level of industrial 

development, and thus allow the largest 

incremental increase in pollution. Areas 

that are not especially sensitive and 

where states have not provided for a 

higher level of industrial growth are 

classified as Class II. When Congress 

established this three-tiered scheme for 

SO2 and PM, it intended that Class II 

areas be subject to an increment that 

allows ‘‘moderately large increases over 

existing pollution.’’ H.R. Rep. 95–294, 4 

LH at 2609. 

Establishing increments at different 

levels for each of the three area 

classifications helps to fulfill two of the 

factors applicable under section 166(c) 

of the Act. First, establishing the 

smallest increments in Class I areas 

helps fulfill EPA’s obligation to 

establish regulations that ‘‘preserve, 

protect, and enhance the air quality’’ in 

parks and special areas. Class I areas are 

primarily the kinds of parks and special 

areas covered by section 160(2) of the 

Act. Second, by providing for two 

additional area classifications with 

increment levels that are higher but still 

protective, the area classification system 

helps satisfy the goal in section 160(3) 

of the Act that EPA ‘‘insure that 

economic growth will occur in a manner 

consistent with preservation of clean air 

resources.’’ In those areas where clean 

air resources may not require as much 

protection, more growth is allowed. By 

employing an intermediate level (Class 

II areas) and higher level (Class III 

areas), this classification scheme helps 

ensure that growth can occur where it 

is needed (Class III areas) without 

putting as much pressure on existing 

clean air resources in other areas where 

some growth is still desired (Class II 

areas). 

By requesting that EPA redesignate an 

existing Class II area to Class III, states 

may accommodate economic growth 

and air quality in areas where the Class 

II increment is too small to allow the 

siting of new or modified sources. The 

procedures specified by the Act for such 

a redesignation require a commitment 

by the State government to create such 

an area, extensive public review, local 

government participation in the SIP area 

redesignation process, and a finding that 

the redesignation will not result in the 

applicable increment being exceeded in 

a nearby Class I or Class II area. See 

sections 164(a) and (b) of the Act. (No 

State has yet requested a Class III 

redesignation.) The EPA believes that 

the three-tiered classification system has 

allowed for economic growth, consistent 

with the preservation of clean air 

resources. 

However, an area classification 

system alone may not completely satisfy 

the factors applicable under section 

166(c) of the Act. The increment that is 

employed for each class of area is also 

relevant to an evaluation of whether the 

area classification system achieves the 

goals of the PSD program. We briefly 

discuss the characteristics of increments 

in section V.E.5. 

One commenter took issue with our 

assessment of the two factors that we 

believe a classification system helps to 

fulfill. As discussed previously in 

section V.C.4, the commenter asserted 

that EPA has unlawfully interpreted 

section 160(3) of the Act to elevate 

economic growth over all other statutory 

factors. As explained in greater detail in 

section V.C.4, we disagree that our 

interpretation elevates economic growth 

over other factors, and believe that the 

plain language of the statute supports 

EPA’s reading that section 160(3) 

requires a balancing of the goals of (1) 

economic growth and (2) preservation of 

existing clean air resources. 

The commenter also stated that EPA 

has failed to demonstrate that the 

classification system and safe harbor 

increments, in combination with the 

other elements of the regulatory 

framework, will ‘‘preserve, protect, and 

enhance the air quality’’ in parks and 

special areas as required under section 

160(2) of the Act. These comments and 

our response to them are found in 

section V.E.6 of this preamble where we 

discuss our evaluation of the safe harbor 

increments. 

3. Permitting Procedures 

Two of the factors applicable under 

section 166(c) are fulfilled by the caseby-case permit review procedures that 

are built into our existing PSD 

regulations. The framework of our 

existing PSD regulations employs the 

preconstruction permitting system and 

procedures required under section 165 

of the Act. These requirements are 

generally reflected in 40 CFR 51.166 and 

52.21 of EPA’s PSD regulations. These 

permitting and review procedures, 

which apply to construction of new 

major sources and to major 

modifications, fulfill the goals set forth 

in sections 160(4) and 160(5) of the Act. 

These goals require that PSD programs 

in one State not interfere with the PSD 

programs in other states and that PSD 

programs assure that any decision to 

permit increased air pollution is made 

after careful evaluation and public 

participation in the decision-making 

process. For the same reasons discussed 

in our proposal for the pollutantspecific NO2 increments regulations (70 

FR 8896, February 23, 2005), we believe 

these factors are also fulfilled for PM2.5

by employing the permit review 

procedures. 

4. AQRV Review by Federal Land 

Manager and Reviewing Authority 

In this final rule, we apply the 

existing requirements to evaluate 

impacts on AQRVs in Class I areas (see 

existing 40 CFR 51.166(p) and 52.21(p)) 

to PM2.5. The existing requirements for 

an AQRV review, which Congress 

applied to SO2 and TSP, provide 

Federal land managers (FLMs) with the 

responsibility to review source impacts 

on site-specific AQRVs in Class I areas 

and to bring any alleged adverse 

impacts to the attention of the reviewing 

authority. Under an increment 

approach, we consider this review to be 

an additional measure that helps satisfy 

the factors in sections 166(c) and 160(2) 

which require EPA’s pollutant-specific 

PSD regulations to protect (1) air quality 

values, and (2) parks and other special 

areas, respectively. 

Two State/local agency commenters 

supported our proposal to apply the 

requirements to evaluate impacts on 

AQRV in Class I areas to PM2.5 review. 

However, one commenter indicated that 

FLM review does not and cannot assure 

the prevention of all significant PM2.5- 

related deterioration because it applies 

only to the construction or modification 

of very large stationary sources (e.g., 

factories and power plants) affecting 

Class I areas. This commenter pointed 

out that Class I areas do not include 

Bureau of Land Management wilderness 

and wilderness study areas 

(encompassing more than 15 million 

acres), 341 of the nation’s 390 national 

park units (only 49 national parks are 

Class I), and many U.S. Forest Service 

lands (including a number of wilderness 

areas). The commenter added that FLM 


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8Even if such a waiver of the Class I increment 

is allowed upon a finding of no adverse impact, the 

source must comply with such emissions 

limitations as may be necessary to ensure that 

alternative increments specified in the rules for SO2

or PM are not exceeded. The alternative increments 

are generally at the level of the Class II increments, 

with the lone exception being a more restrictive 3- 

hour increment for SO2. Section 165(d)(2)(C)(iv). 

The EPA made this provision applicable to the PSD 

provisions for NOX at the level of the NO2 Class II 

increment (53 FR 3704; 53 FR 40656) and 

substituted the PM10 Class II increments for the 

statutory alternative PM increments, which were 

based on TSP (58 FR 31622). This final rule 

expands this provision to include the PM2.5 Class 

II increments as well. See 40 CFR 51.166(p)(4) and 

52.21(p)(5). 

9 In response to concerns that Class I increment 

would hinder growth in areas surrounding the Class 

I area, Congress established Class I increments as a 

means of determining where the burden of proof 

should lie for a demonstration of adverse effects on 

AQRVs. See Senate Debate, June 8, 1977 (3 LH at 

725). 

10See S. Rep. 95–127, at 12, reprinted at 3 LH at 

1386, 1410 (describing the goal of protecting ‘‘air 

quality values’’ in ‘‘Federal lands—such as national 

parks and wilderness areas and international 

parks,’’ and in the next paragraph and subsequent 

text using the term ‘‘air quality related values’’ to 

describe the same goal); id. at 35, 36 (‘‘The bill 

charges the Federal land manager and the 

supervisor with a positive role to protect air quality 

values associated with the land areas under the 

jurisdiction of the [FLM]’’ and then describing the 

statutory term as ‘‘air quality related values’’). H.R. 

Report 95–564 at 532 (describing duty of 

Administrator to consider ‘‘air quality values’’ of the 

tribal and State lands in resolving an appeal of a 

tribal or State redesignation, which is described in 

the final bill as ‘‘air quality related values’’). 

review does not help to fulfill section 

160(2)’s goal of preserving and 

protecting air quality in ‘‘other areas of 

special national or regional natural, 

recreational, scenic, or historic value,’’ 

such as State and local parks, wildlife 

refuges, recreation areas, lakes, and 

historic areas, none of which are Class 

I areas. In addition, the commenter 

noted that FLM review does not apply 

to emissions increases from sources of 

PM2.5 and precursor pollution other 

than major stationary sources, such as 

motor vehicles and non-major industrial 

sources (which are sources that emit 

substantial amounts of PM2.5 and 

precursors). Alabama Power v. Costle, 

636 F.2d 323, 362 (D.C. Cir. 1979) 

(Alabama Power) (expressly recognizing 

that ‘‘[s]ignificant deterioration may 

occur due to increased emissions from 

unregulated minor sources.’’). 

The commenter also asserted that 

FLM review is of limited reach even 

where it does apply. Under the current 

PSD regulations, a State must consider 

an FLM’s objections and must justify its 

decision in writing when it disagrees 

with those objections, but the State can 

still issue a PSD permit over those 

objections unless emissions are 

predicted to cause an exceedance of the 

applicable increment. The commenter 

believes that, given these limitations, 

EPA cannot plausibly claim that the 

existing provision for FLM review 

ensures the preservation, protection, 

and enhancement of air quality for parks 

and natural areas throughout the nation 

as required by section 160(2) of the Act. 

In our rulemakings addressing PSD 

for NOX, EPA extended the AQRV 

review procedures set forth in 40 CFR 

51.166(p) and 52.21(p) to cover NO2. 

These AQRV review procedures were 

established based on section 165(d) of 

the Act, and they were originally 

applied only in the context of the 

statutory increments for PM and SO2. 

However, because they also address 

many of the factors applicable under 

section 166(c) of the Act, EPA also 

applied them to NOX through 

regulation. In this final rule, we are 

amending the existing PSD regulations 

to extend, as proposed, the AQRV 

review procedures to include PM2.5 by 

explicitly including PM2.5 in the 

regulatory text that now simply 

references ‘‘particulate matter.’’ See new 

40 CFR 51.166(p)(4) and 52.21(p)(5). 

Section 165(d) creates a scheme in 

which the FLM and reviewing authority 

must review the impacts of a proposed 

new or modified source’s emissions on 

AQRVs. The Act assigns to the FLM an 

‘‘affirmative responsibility’’ to protect 

the AQRVs in Class I areas. This is in 

notable contrast to the reviewing 

authority’s responsibility for protecting 

the increments—including Class I 

increments. The FLM may object to or 

concur in the issuance of a PSD permit 

based on the impact, or lack thereof, 

that new emissions may have on any 

affected AQRV that the FLM has 

identified and for which information is 

available to the general public. If the 

proposed source’s emissions are shown 

not to cause or contribute to a violation 

of a Class I increment, the FLM may still 

prevent issuance of the permit by 

demonstrating to the satisfaction of the 

reviewing authority that the source or 

modification will have an adverse 

impact on AQRVs. Section 165(d)(2)(C). 

On the other hand, if the proposed 

source is shown to cause or contribute 

to a violation of a Class I increment, the 

reviewing authority (State or EPA) shall 

not issue the permit unless the owner or 

operator demonstrates to the satisfaction 

of the FLM that there will be no adverse 

impact on AQRVs.8 Thus, the showing 

of compliance with the increment 

determines whether the FLM or the 

permit applicant has the burden of 

satisfactorily demonstrating whether or 

not the proposed source’s emissions 

would have an adverse impact on 

AQRVs.9 In any event, the FLM plays an 

important and material role by raising 

these issues for consideration by the 

reviewing authority, which in the 

majority of cases will be the State. 

Extending the AQRV review 

procedures of the PSD regulations to 

PM2.5 helps to provide protection with 

respect to potential adverse effects from 

PM2.5 for parks and special areas (which 

are generally the Class I areas subject to 

this review) not afforded by the 

increment system alone. As discussed 

later, we believe the factors applicable 

under section 166(c) of the Act can be 

fulfilled when the review of AQRVs is 

applied in conjunction with increments 

and other aspects of our PSD 

regulations. In those cases where the 

increment is not violated and the 

reviewing authority agrees that a 

proposed project will adversely affect 

AQRVs, the parks and other special 

areas will be protected by denying 

issuance of the permit or by requiring 

the applicant to modify the project to 

alleviate the adverse impact. 

We read the legislative history to 

show that Congress intended the AQRV 

review provisions of section 165(d) to 

provide a special layer of protection, 

beyond that provided by increments. 

The Senate committee report stated the 

following: 

A second test of protection is provided in 

specified Federal land areas (Class I areas), 

such as national parks and wilderness areas; 

these areas are also subjected to a review 

process based on the effect of pollution on 

the area’s air quality related values.’’ 

S. Rep. 95–127, at 17, 4 LH at 1401. 

As we stated in the NO2 increment 

rule, we believe the term ‘‘air quality 

values’’ should be given the same 

meaning as ‘‘air quality related values.’’ 

Legislative history indicates that the 

term ‘‘air quality value’’ was used 

interchangeably with the term ‘‘air 

quality related value’’ (AQRV) regarding 

Class I lands.10

The commenter is correct that the 

FLM (or AQRV) review applies only to 

Class I areas, and not to other ‘‘special’’ 

areas such as the numerous State and 

local parks and some other areas that 

could be seen as being covered by the 

protective purposes of section 160(2) of 

the Act. This level of coverage by FLM 

review to protect AQRVs was 

established by Congress when it enacted 

the PSD program, including the 

purposes set out in section 160(2). Thus, 

we conclude that Congress believed that 

the special areas not designated as Class 

I areas were properly addressed by the 

other elements of the PSD program. As 

discussed further in the next section, 

one such element is the requirement for 

sources to conduct an ‘‘additional 

impacts analysis,’’ which includes an 


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analysis of the impacts on visibility, 

soils, and vegetation of the proposed 

source and associated growth, regardless 

of the classification of the area impacted 

by the source. Note also that states have 

the option under the Act of designating 

additional areas as Class I areas and 

providing for AQRV review for these 

State Class I areas if they believe that 

there are areas within their borders that 

merit such protection. 

The commenter is not correct in 

saying that the review to protect AQRVs 

does not apply to emissions increases 

from sources other than major stationary 

sources. While it is generally true that 

a major stationary source may trigger the 

analysis as part of the required PSD 

review for new major stationary sources 

and major modifications where such 

source’s emissions increase may affect a 

Class I area, the review itself includes 

the impacts on an AQRV of other 

emissions in the area, including 

emissions from non-major sources. In 

addition, states may adopt requirements 

in their State implementation plans to 

require certain minor sources seeking a 

permit to undergo an AQRV analysis if 

they choose to do so. 

We agree with the commenter that the 

AQRV review has certain limitations in 

that a State can, under some 

circumstances, issue a PSD permit over 

the objection of the FLM. Here again, 

Congress enabled this outcome when it 

provided that a permit would not be 

issued when the FLM demonstrates ‘‘to 

the satisfaction of the State’’ that the 

source will have an adverse impact on 

AQRVs in a Class I area. Section 

165(d)(2)(C)(ii). We read this provision 

to reflect Congress’s judgment on the 

appropriate balance between State and 

FLM discretion in the reach of AQRV 

review. That said, when a reviewing 

authority declines to follow a 

determination of adverse impact by the 

FLM, the reviewing authority is 

expected to provide a rational basis for 

doing so, and a reviewing authority’s 

rejection of an FLM’s finding may not be 

arbitrary and capricious. As stated by 

EPA’s Environmental Appeals Board in 

In the Matter of: Hadson Power 14— 

Buena Vista, 4 E.A.D. 258, 1992 WL 

345661 (October 5, 1992)(in Section 

II.A): 

States do not have unfettered discretion to 

reject an FLM’s adverse impact 

determination. If a State determines that an 

FLM has not satisfactorily demonstrated an 

adverse impact on AQRVs from the proposed 

facility, the State must provide a ‘‘rational 

basis’’ for such a conclusion, ‘‘given the 

FLMs’ affirmative responsibility and 

expertise regarding the Class I areas within 

their jurisdiction.’’ 50 FR 28549, July 12, 

1985. Arbitrary and capricious rejections of 

adverse impact determinations are not 

sustainable. (citations omitted). 

In sum, the commenter correctly 

enumerated some of the limitations of 

the AQRV review under the Act. 

However, such review is only one 

element of the full PSD program, which 

must be evaluated against the statutory 

requirements in their entirety. We 

continue to believe, as previously 

stated, that under an increment 

approach, FLM review for AQRV 

impacts is an additional measure that 

helps satisfy the factors in sections 

166(c) and 160(2) of the Act (which 

require EPA’s pollutant-specific PSD 

regulations to protect (1) air quality 

values, and (2) parks and other special 

areas, respectively) in balance with the 

other statutory factors. We add that the 

AQRV review requirements of the 

existing regulations mirror these 

requirements in the Act, which reflect 

Congress’ judgment of how AQRV 

review should properly be used to 

promote the purposes of the program as 

set out in section 160 of the Act. 

5. Additional Impacts Analysis 

The ‘‘additional impacts analysis’’ 

requirements set forth in our part 51 and 

52 PSD regulations also help fulfill the 

criteria and goals and purposes in 

sections 166(c) and 160. The additional 

impacts analysis involves a case-by-case 

review of potential harm to visibility, 

soils, and vegetation in Class II and III 

areas that could occur from the 

construction or modification of a PSD 

source. 

Sections 51.166(o)(1) and 52.21(o)(1) 

of the PSD regulations require that a 

permit provide the following analysis: 

An analysis of the impairment to visibility, 

soils and vegetation that would occur as a 

result of the source or modification and 

general commercial, residential, industrial 

and other growth associated with the source 

or modification. The owner or operator need 

not provide an analysis of the impact on 

vegetation having no significant commercial 

or recreational value. 

This requirement was based on 

section 165(e)(3)(B) of the Act, which 

provides that EPA establish regulations 

that require ‘‘an analysis of the ambient 

air quality, climate and meteorology, 

terrain, soils and vegetation, and 

visibility at the site of the proposed 

major emitting facility and in the area 

potentially affected by emissions from 

such facility * * *.’’ 

As mentioned in the previous section, 

one commenter argued that the 

provisions for protection of Class I areas 

are of no help in fulfilling the goal set 

forth in section 160(2) of the Act to 

preserve and protect air quality in the 

countless ‘‘other areas of special 

national or regional natural, 

recreational, scenic, or historic value’’ 

such as State and local parks, wildlife 

refuges, recreation areas, lakes and 

historic areas, none of which were 

originally defined by Congress as Class 

I areas. 

We acknowledge that the special 

provisions for protecting Class I areas 

are not applicable for protecting areas 

that are not designated as ‘‘Class I.’’ 

However, we believe that the 

‘‘additional impacts analysis’’ provisions 

are especially helpful for satisfying the 

requirements of section 166(c) in Class 

II and Class III areas, including the types 

of areas described by the commenter, 

that are not Class I areas but are worthy 

of special protection beyond what might 

be provided by the NAAQS and 

increments. 40 CFR 51.166(o) and 

52.21(o). These areas are not subject to 

the special AQRV review that applies 

only in Class I areas. While the 

additional impacts analysis is not as 

intensive a review as the AQRV analysis 

required in Class I areas, the 

requirement to consider impairments to 

visibility, soils, and vegetation through 

the additional impacts analysis 

contributes to satisfying the factors 

applicable under section 166(c) of the 

Act in all areas, including Class II and 

Class III areas. 

6. Installation of BACT 

The requirement that new sources and 

modified sources subject to PSD apply 

BACT is an additional measure that 

helps to satisfy the factors in sections 

166(c), 160(1), and 160(2) of the Act. 

This requirement, based on section 

165(a)(4) of the Act, is already included 

in EPA’s PSD regulations for all 

pollutants generally and thus, in the 

2007 NPRM we considered it to be a 

part of the regulatory framework for the 

Agency’s pollutant-specific regulations 

for PM2.5. 40 CFR 51.166(j) and 52.21(j). 

Our existing regulations define ‘‘best 

available control technology’’ as ‘‘an 

emission limitation * * * based on the 

maximum degree of reduction for each 

pollutant subject to regulation under the 

Act * * * which the Administrator, on 

a case-by-case basis, taking into account 

energy, environmental, and economic 

impacts and other costs, determines is 

achievable for such source through 

application of production processes or 

available methods, systems, and 

techniques * * *.’’ 40 CFR 

51.166(b)(12) and 52.21(b)(12). This 

pollutant control technology 

requirement, in practice, has required 

significant reductions in the pollutant 

emissions increases from new and 

modified sources while also stimulating 

the on-going improvement of control 


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11We have paraphrased these factors here and in 

other sections to facilitate the explanation of our 

reasoning. However, we recognize, as we did in our 

regulation for NOX, that the statutory language is 

broader than the shorthand we use here for 

convenience. 

12Note that the PM10 increment may still be more 

limiting in areas where much of that increment has 

already been consumed. 

13The 24-hour PM2.5 NAAQS (35 μg/m3) is about 

23 percent of the 24-hour PM10 NAAQS (150 μg/ 

m3). 

technology. The control of PM2.5

emissions through the application of 

BACT helps to protect air quality 

values, public health and welfare, and 

parks and other special areas. 

E. Final PM2.5 Increments 

Based on our evaluation of the effects 

of PM2.5 and a balancing of the criteria 

in section 166(c) of the Act (and the 

incorporated goals and purposes of the 

Act contained in section 101 and the 

statutory PSD program in section 160 of 

the Act), EPA has concluded that the 

‘‘safe harbor’’ increments for PM2.5

(which satisfy section 166(d) of the Act) 

are sufficient to fulfill the criteria in 

section 166(c) when combined with the 

other measures described earlier that we 

apply to PM2.5. Since several of the eight 

factors applicable under section 166(c) 

are satisfied by adopting the framework 

and other measures described earlier, 

our development of these increments for 

PM2.5 was guided by the four remaining 

factors that may not be fully satisfied by 

the framework and other measures: (1) 

Protecting AQRVs; (2) protecting the 

public health and welfare from 

reasonably-anticipated adverse effects; 

(3) protecting the air quality in parks 

and special areas, and (4) insuring 

economic growth.11 In accordance with 

the ‘‘contingent safe harbor’’ approach, 

to determine the specific characteristics 

of the proposed increments, we first 

established safe harbor increments 

representing the level of effectiveness 

necessary to satisfy the ‘‘at least as 

effective as’’ requirement in section 

166(d) of the Act and then conducted 

further analysis to determine if 

additional measures are necessary to 

fulfill the requirements of section 

166(c). 

1. Identification of Safe Harbor 

Increments 

Using the percentage-of-NAAQS 

approach under proposed Option 1, as 

explained in section V.C.2 of this 

preamble, we derived the following safe 

harbor increments for PM2.5: 

Averaging period NAAQS 

(μg/m3) 

Increments (μg/m3) 

Class I Class II Class III 

Annual .............................................................................................................................. 15 1 4 8 

24-hour ............................................................................................................................. 35 2 9 18 

The table shows PM2.5 NAAQS levels 

(primary and secondary NAAQS) at 15 

μg/m3 for the annual averaging time and 

35 μg/m3 for the 24-hour averaging time. 

See 40 CFR 50.7. From these NAAQS 

levels, we calculated the safe harbor 

increments based on the same 

percentages that were used by Congress 

to establish the original PM increments 

(measured as TSP) in section 163 of the 

Act, i.e., 6.6 percent of the NAAQS for 

Class I areas, 25 percent of the NAAQS 

for Class II areas, and 50 percent of the 

NAAQS for Class III areas. We have 

concluded that increments with these 

characteristics are sufficient to satisfy 

the requirement in section 166(d) that 

we adopt increments (or other PSD 

regulations) that are ‘‘at least as effective 

as’’ the increments established in section 

163 of the Act. See EDF v. EPA, 898 

F.2d at 188, 190. 

Nine commenters supported proposed 

Option 1, either explicitly or implicitly 

supporting our method of calculating 

the safe harbor increments used to 

develop increments for PM2.5. One of 

these commenters, while agreeing with 

the safe harbor increment approach 

under Option 1, disagreed with our 

analysis of the adequacy of the safe 

harbor increments, as discussed in other 

sections of this preamble. One 

commenter who opposed Option 1 

(based on the belief that section 166(a) 

of the Act is not the appropriate basis 

for PM2.5 increments) nevertheless 

supported the percentage-of-NAAQS 

approach for developing PM2.5

increments under the statutory authority 

at section 166(f). 

A commenter who opposed our 

proposal to calculate increments using 

percentages of the NAAQS argued that 

this approach for setting the PM2.5

increments is not scientifically 

supported. This commenter indicated 

that basing the PM2.5 increments on the 

same percentage of the NAAQS that 

were used to set PM10 increments based 

on the TSP NAAQS ignores the 

relationship between PM10 and PM2.5

emissions, which may be much different 

than the relationship between TSP and 

PM10 emissions. The commenter argued 

that, because the ratio of PM2.5 to PM10

emissions is 0.8, it appears that using 

the percentages proposed by EPA would 

indirectly restrict PM10/TSP emissions 

and air quality impacts to 

proportionally lower levels than the 

PM10 increments in order to avoid 

exceeding the PM2.5 increments. The 

commenter conceded that using the 0.8 

factor to set PM2.5 increments may seem 

too high, but asserted that using the safe 

harbor approach would set increments 

for PM2.5 that are too low. 

We conclude that the commenter is 

mistaken in saying that the PM2.5

increments use the same percentage of 

the NAAQS that were used to set the 

PM10 NAAQS. We adopted the PM10

increments using the ‘‘equivalent 

substitution’’ approach set forth under 

section 166(f) of the Act. Under that 

approach, rather than calculating the 

PM10 increments as specific percentages 

of the PM10 NAAQS (using the same 

percentages that Congress used for 

setting the statutory increments for PM 

and SO2), EPA determined the levels of 

the PM10 increments that could 

represent an equivalent amount of 

increment consumed, as if the TSP 

increments were still in effect. See 58 

FR 31622, June 3, 1993, at 31626–31627. 

Nevertheless, the commenter is correct 

that, in cases where the ratio of PM2.5 to 

PM10 emissions is 0.8 for an individual 

source, the source may have to reduce 

its PM10 emissions more than would 

otherwise be necessary to meet the PM10

increments in order to control its PM2.5

emissions sufficiently to meet the safe 

harbor PM2.5 increments.12 This is 

because the safe harbor PM2.5

increments are less than 80 percent of 

the PM10 increments. For example, the 

Class II 24-hour PM2.5 safe harbor 

increment (9 μg/m3) is only 30 percent 

of the corresponding PM10 increment 

(30 μg/m3). 

The underlying reason that the safe 

harbor PM2.5 increments are so much 

less than the PM10 increments is that the 

PM2.5 NAAQS are much less than the 

PM10 NAAQS.13 This is the result of the 

evolution in our knowledge about the 

health and welfare effects of PM, in 

particular the effects of the fine PM 


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14The review completed in 2006 updated the 

previous review, which began in 1994 and resulted 

in revised standards for PM in 1997. 

represented by PM2.5. We believe that it 

is fitting for PM2.5 increments to reflect 

our greater knowledge about PM2.5

effects (as embodied in the NAAQS), 

rather than to simply maintain the 

control level required by the PM10

increments as suggested by the 

commenter. If this results in PM2.5

increments that are more limiting than 

PM10 increments, we believe that this 

outcome is appropriate in light of our 

statutory requirement to prevent 

significant deterioration of air quality as 

it relates to PM2.5. 

2. Data Used by EPA for the Evaluation 

of the Safe Harbor Increments for PM2.5

We evaluated whether measures other 

than the safe harbor increments are 

necessary by analyzing primarily the 

scientific and technical information on 

the health and welfare effects of PM2.5

contained in the June 2005 OAQPS Staff 

Paper which accompanied the last full 

review of the PM NAAQS completed in 

2006.14

Section 166(a) of the Act provides that 

EPA establish pollutant-specific PSD 

regulations, such as increments, after 

the establishment of a NAAQS for the 

applicable pollutants. The Act provides 

that EPA will promulgate new PSD 

regulations under section 166, including 

new increments if appropriate, within 2 

years from the promulgation of any 

NAAQS after 1977. Within that time 

frame, the health and welfare 

information used for the setting of the 

NAAQS would also be ‘‘current’’ for 

purposes of establishing pollutantspecific PSD regulations. We believe 

this timing reflects congressional intent 

that EPA consider the same body of 

information concerning a pollutant’s 

health and welfare effects when it 

promulgates the NAAQS and 

subsequent PSD increments (or other 

measures) defining significant air 

quality deterioration for the same 

pollutant. However, when we used that 

same information as the basis for our 

proposed pollutant-specific PSD 

regulations, we evaluated that 

information under the legal criteria in 

section 166 of the Act rather than the 

criteria in section 109 applicable to the 

promulgation of NAAQS. See EDF v. 

EPA, 898 F.2d at 190. 

At the time of our proposal of PM2.5

increments, we had just completed a 

review of the PM2.5 NAAQS. Thus, the 

information used in the NAAQS review 

was current and timely for purposes of 

establishing pollutant-specific PSD 

regulations for PM2.5. On October 17, 

2006, based primarily on considerable 

new data on the air quality and human 

health effects for PM2.5 directly, EPA 

revised the primary and secondary 

NAAQS to provide increased protection 

of public health and welfare by 

retaining the level of the annual 

standard and tightening the level of the 

24-hour standard from 65 to 35 μg/m3

while retaining the 24-hour PM10

NAAQS and revoking the annual PM10

NAAQS. The information contained in 

both the 2004 Criteria Document and 

2005 Staff Paper that was used for the 

latest review of the PM NAAQS was 

also considered for the purpose of 

evaluating the PM2.5 increments that we 

have established in this final rule. 

The 2004 Criteria Document and 2005 

Staff Paper are the products of a 

rigorous process that is followed to 

validate and interpret the available 

scientific and technical information, 

and provided the basis for 

recommending the PM2.5 NAAQS. In 

accordance with the Act, the NAAQS 

process begins with the development of 

‘‘air quality criteria’’ under section 108 

for air pollutants that ‘‘may reasonably 

be anticipated to endanger public health 

or welfare’’ and that come from 

‘‘numerous or diverse’’ sources. Section 

108(a)(1). For each NAAQS review, the 

Administrator must appoint ‘‘an 

independent scientific review 

committee composed of seven members 

of the National Academy of Sciences, 

one physician, and one person 

representing State air pollution control 

agencies,’’ known as the Clean Air 

Scientific Advisory Committee 

(CASAC). Section 109(d)(2)(A). The 

CASAC is charged with recommending 

revisions to the criteria document and 

NAAQS, and advising the Administrator 

on several issues, including areas in 

which additional knowledge is required 

to appraise the adequacy and basis of 

existing, new, or revised NAAQS. 

Section 109(d)(2)(B),(C). 

‘‘Air quality criteria’’ must reflect the 

latest scientific knowledge on ‘‘all 

identifiable effects on public health or 

welfare’’ that may result from a pollutant 

presence in the ambient air. Section 

108(a)(2). The scientific assessments 

constituting air quality criteria generally 

take the form of a ‘‘criteria document,’’ 

a rigorous review of all pertinent 

scientific studies and related 

information. The EPA also develops a 

‘‘staff paper’’ to ‘‘bridge the gap’’ between 

the scientific review and the judgments 

the Administrator must make to set 

standards. See Natural Resources 

Defense Council v. EPA (‘‘NRDC ’’), 902 

F.2d 962, 967 (D.C. Cir. 1990). Both 

documents undergo extensive scientific 

peer review as well as public notice and 

comment. See, e.g., 62 FR 386542. 

3. Scope of Effects Considered 

The effects of ambient PM2.5

concentrations may include effects from 

secondarily-formed PM2.5. Thus, when 

we analyzed the data in this rulemaking, 

we evaluated the health and welfare 

effects of both direct PM2.5 and 

secondarily-formed PM2.5 that may 

result from the transformation of other 

pollutants such as SO2 and NOX. This 

was consistent with the approach we 

described for addressing these effects in 

the review of our pollutant-specific NO2

increments regulations. 70 FR 59590. 

4. Evaluation of the Health and Welfare 

Effects of PM2.5

Airborne PM is not a specific 

chemical entity, but rather is a mixture 

of liquid and solid particles from 

different sources and of different sizes, 

compositions, and properties. Particle 

size distributions show that atmospheric 

particles exist in two classes: Fine 

particles and coarse particles. The 

indicator for fine particles is PM2.5, 

which represents that population of 

particles that is mostly less than 2.5 

micrometers in size. The indicator for 

thoracic coarse particles is ‘‘PM10–2.5,’’ 

which represents particles sized 

between 2.5 and 10 micrometers. In the 

last two reviews of the PM NAAQS, 

EPA concluded that these two 

indicators, because of their different 

sources, composition, and formation 

processes, should be treated as separate 

subclasses of PM pollution for purposes 

of setting ambient air quality standards. 

Fine PM is derived directly from 

combustion material that has volatilized 

and then condensed to form primary PM 

or from precursor gases, such as SO2

and NOX, reacting in the atmosphere to 

form secondary PM. Major components 

of fine particles are sulfates, strong acid, 

ammonium nitrate, organic compounds, 

trace elements (including metals), 

elemental carbon, and water. Primary 

and secondary fine particles have long 

lifetimes in the atmosphere (days to 

weeks) and travel long distances 

(hundreds to thousands of kilometers). 

They tend to be uniformly distributed 

over urban areas and larger regions, 

especially in the eastern United States. 

As a result, they are not easily traced 

back to their individual sources. 

a. Health Effects 

The EPA reported important progress 

since the last PM NAAQS review in 

advancing our understanding of 

potential mechanisms by which ambient 

PM2.5, alone and in combination with 

other pollutants, is causally linked to a 


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15 It should be noted, however, that an increment 

does not allow air pollution levels in an area to 

increase beyond the ambient concentration of a 

pollutant that would exceed the level allowed by 

the NAAQS. 

number of key health effects. The more 

extensive and stronger body of evidence 

used by EPA to study the health effects 

of PM2.5 in our latest review identified 

a broader range of effects than those 

previously documented, involving 

premature mortality and indices of 

morbidity (including respiratory 

hospital admissions and emergency 

room visits, school absences, work loss 

days, restricted activity days, effects on 

lung function and symptoms, 

morphological changes, and altered host 

defense mechanisms) associated with 

both long-term and short-term exposure 

to PM2.5. A more detailed discussion of 

the health effects associated with PM2.5

is contained in the 2007 NPRM. 72 FR 

54127–54128. In addition, an overview 

of the scientific and technical evidence 

considered in the 2004 Criteria 

Document and 2005 Staff Paper can be 

found in our proposed rule for revising 

the NAAQS for PM (71 FR 2619, January 

17, 2006). 

b. Welfare Effects 

Ambient PM alone, and in 

combination with other pollutants, can 

have a variety of effects on public 

welfare. While visibility impairment is 

the most noticeable effect of fine 

particles present in the atmosphere, 

both fine and coarse particles can have 

other significant welfare-related effects, 

including effects on vegetation and 

ecosystems, materials (e.g., soiling and 

corrosion), and climate change 

processes. 

In reaching our decision in 2006 to 

revise the suite of PM secondary 

standards, EPA factored in several key 

conclusions from the scientific and 

technical information contained in the 

2004 Criteria Document and 2005 Staff 

Paper. These conclusions included the 

following: (1) PM-related visibility 

impairment is principally related to fine 

particle levels, and most directly related 

to instantaneous levels of visual air 

quality associated with short-term 

averaging periods; (2) PM2.5

concentrations can be used as a general 

surrogate for visibility impairment in 

urban areas; (3) any secondary NAAQS 

for visibility protection should be 

considered in conjunction with the 

regional haze program as a means of 

achieving appropriate levels of 

protection against PM-related visibility 

impairment in urban, non-urban, and 

Class I areas nationwide; (4) the 

available evidence is not sufficient to 

support distinct secondary standards for 

fine or coarse particles for any nonvisibility related welfare effects; and (5) 

the secondary standards should be 

considered in conjunction with 

protection afforded by other programs 

intended to address various aspects of 

air pollution effects on ecosystems and 

vegetation, such as the acid deposition 

program and other regional approaches 

to reducing pollutants linked to nitrate 

or acidic deposition. 

In this rulemaking, EPA has reviewed 

the scientific and technical information 

concerning welfare related effects 

considered in the 2004 Criteria 

Document and 2005 Staff Paper to 

determine whether there is any basis for 

modifying the safe harbor increments 

developed for PM2.5 to satisfy the 

criteria under sections 166(c) and 160 of 

the Act. Our review included 

information on visibility impairment, 

and effects on vegetation and other 

ecosystem components, materials and 

soiling, and climate changes. A detailed 

discussion of the various welfare effects 

we considered for evaluating the safe 

harbor increments for PM2.5 is contained 

in the 2007 NPRM. 72 FR 54128–54133. 

5. Fundamental Elements of Increments 

As we have previously noted, under 

the model established in the Act and 

prior EPA regulations, the function of an 

increment is not like that of the NAAQS 

in that an increment is not intended to 

set a uniform ambient pollutant 

concentration ‘‘ceiling’’ across the 

United States. See 70 FR 59600. Instead, 

while both increments and NAAQS 

generally serve to limit ambient air 

pollution levels, increments are 

designed to allow a uniform amount of 

pollutant concentration increase for 

each area in the United States having a 

particular classification, i.e., Class I, II, 

or III. The amount of the allowable 

increase is measured against a baseline 

air quality level that is typically 

different for each particular area.15

Because the baseline air quality level 

varies from one location to another, and 

is not established for a particular area 

until a source proposing to construct in 

that area submits a complete PSD permit 

application, it is not possible to 

determine what the maximum ambient 

pollutant concentration attainable will 

be for a given area (to be used to 

determine the protection afforded by an 

increment against potential adverse 

environmental effects) until the specific 

baseline air quality level is known. 

For the reasons described in our NO2

increments rule, our objective is to 

establish uniform increments, consistent 

with the increments for SO2 and PM 

originally established by Congress, that 

allow the same level of deterioration for 

each area of the country having the 

same classification. 70 FR 59601. It is 

important to understand that increments 

are not intended to reduce ambient 

concentrations of an air pollutant below 

existing baseline levels in each area, but 

rather to define a level of allowable 

increase in pollutant concentrations 

above baseline levels, and to identify 

the level at which ‘‘significant’’ 

deterioration occurs for each area, in 

accordance with its specific 

classification. 70 FR 59600. 

6. Evaluation of the Safe Harbor 

Increments 

As indicated earlier (in section V.E.2 

of this preamble), mindful of the 

considerations made about the 

fundamental characteristics of the 

increments, we reviewed the scientific 

and technical evidence available for the 

2005 review of the NAAQS for PM in 

order to determine whether, and to what 

extent, the ‘‘safe harbor’’ increments 

might need to be modified in order to 

protect air quality values, health and 

welfare, and parks while insuring 

economic growth consistent with the 

preservation of clean air resources in 

accordance with sections 166(c) and 160 

of the Act. As we did in our evaluation 

of the safe harbor NO2 increments (70 

FR 59603–59606), we relied on an 

approach that evaluates how protective 

the safe harbor PM2.5 increments are by 

comparing the marginal pollutant 

concentration increases allowed by the 

safe harbor increment levels against the 

pollutant concentrations at which 

various environmental responses occur. 

We analyzed the available evidence 

from both a quantitative and qualitative 

perspective to reach a decision about 

whether we should modify the 

contingent safe harbor PM2.5 increments 

and whether we have sufficient 

information to select a specific 

alternative level, averaging time, or 

pollutant indicator for the increments. 

As a result of our analysis, we proposed 

to conclude that it was not necessary to 

modify the safe harbor increments to 

protect human health, address nonvisibility welfare effects, or further 

protect visibility. This analysis is 

described in detail in the 2007 NPRM. 

After considering the comments on 

our evaluation of the safe harbor 

increments and the conclusions we 

reached in the 2007 NPRM (summarized 

in the following paragraphs), we 

continue to believe that the safe harbor 

increments for PM2.5 (which satisfy 

section 166(d) of the Act) are sufficient 

to fulfill the criteria in section 166(c) of 

the Act (and the incorporated goals and 

purposes of the Act in section 101 and 

the PSD program in section 160) when 


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16 Docket No. EPA–HQ–OAR–2006–0605 can be 

accessed on line at http://www.regulations.gov. 

17 In the 2005 OAQPS Staff Paper reviewing the 

NAAQS for PM, EPA cited the following accepted 

definition of ‘‘critical load’’: ‘‘quantitative estimate 

of an exposure to one or more pollutants below 

which significant harmful effects on specified 

sensitive elements of the environment do not occur 

according to present knowledge.’’ See page 6–45. 

combined with the other measures 

described earlier that we apply to PM2.5. 

Consequently, this final rule establishes 

the PM2.5 increments at the level of the 

proposed safe harbor increments. 

An environmental group submitted 

extensive comments arguing that the 

PM2.5 safe harbor increments are not 

sufficient to meet the Act’s requirements 

for PSD and that our analysis was 

inadequate, and two other commenters 

submitted more narrowly targeted 

comments in this area. A summary of 

the major comments, along with our 

responses, follows. A more detailed 

treatment of the comments can be found 

in the Response to Comments document 

for this rulemaking, which is available 

in the rulemaking docket.16

The environmental group commenter 

stated that EPA has not complied with 

section 166(c) of the Act because the 

Agency has not made a finding or 

demonstrated that the PM2.5 PSD rules 

will (as required by section 160(2) of the 

Act) preserve, protect, and enhance the 

air quality in parks and special areas. 

The commenter asserted that EPA 

offered only vague assertions that the 

proposed increments would ‘‘satisfy’’ the 

statutory factors and that they, along 

with other programs, would ‘‘help’’ to 

fulfill the statutory purposes. The 

commenter went on to argue that EPA 

sought to excuse its failure to show 

fulfillment of the statutory purposes by 

asserting that it cannot develop a 

uniform, quantitative, dose-response 

relationship between fine particle levels 

and certain ecosystem impacts (citing 72 

FR 54134), but that, even if true, such 

a claim does not excuse the agency from 

satisfying its statutory duty under 

section 166(c). 

We conclude that the 2007 NPRM 

demonstrated that the safe harbor 

increments, in combination with the 

other aspects of the regulatory 

framework, fulfill the statutory 

requirements despite the scientific 

uncertainties. We reiterate that finding 

today. The fact that we did not, in the 

2007 NPRM, explicitly state this as a 

finding does not diminish the 

demonstration made there and 

reiterated in this preamble. 

The environmental group commenter 

believes that the relationship between 

PM2.5 and adverse effects can be 

quantified to a greater extent than stated 

by EPA. Regarding acid rain and other 

adverse ecological impacts, the 

commenter asserted that critical loads 

can be established as a way of 

quantifying and limiting the PM2.5

contribution to degradation, and noted 

that critical loads are now used by 

authorities in Europe, have been 

endorsed by leading North American 

scientists, and have been used by 

Federal land management agencies. To 

comply with section 166(c), the 

commenter believes that EPA must 

establish a mechanism to supplement 

the nationally uniform increments with 

additional measures, including a 

requirement to establish area-specific 

critical loads or equally protective 

limits, where necessary to protect and 

enhance air quality in specific parks and 

natural areas. 

With regard to the critical load 

concept, we agree conceptually with the 

commenter that critical loads could be 

used to supplement the existing 

increments, especially as a means of 

protecting the known sensitive 

ecosystems within Class I areas. While 

we disagree that the critical loads 

concept can be used as an effective 

replacement to increments for limiting 

air quality degradation, we believe that 

the concept offers considerable promise 

in helping to protect sensitive receptors 

in specific Class I areas. However, we do 

not believe that it would be appropriate 

at this time to establish a requirement 

for area-specific critical loads under the 

PSD program. In our 2005 PSD rule for 

NO2 increments, we indicated that 

states could propose using information 

on critical loads as part of their 

approach for managing air quality in 

their individual SIP-approved PSD 

programs, but sufficient information 

was not yet available for EPA to 

incorporate the use of critical loads into 

the national PSD program. See 70 FR 

59613. 

The concept of critical loads is useful 

for estimating how much pollution a 

particular ecosystem can experience on 

a prolonged basis without showing 

adverse effects. In addition to 

addressing the opportunity for using 

critical loads under its NO2 increment 

rule, EPA has addressed the concept of 

critical loads in the last review of the 

PM NAAQS and currently in the 

secondary NO2/SO2 NAAQS review.17

To date in the United States, critical 

loads have had their primary 

application in the area of atmospheric 

deposition of sulfur (S) and nitrogen 

(N). In the last review of the PM 

NAAQS, EPA found that ambient PM 

was contributing to the total load of 

pollutants entering the U.S. ecosystem 

annually. However, the review also 

concluded that there were ‘‘insufficient 

data for the vast majority of U.S. 

ecosystems that differentiate the PM 

contribution to total N [nitrate] or S 

[sulfate] deposition to allow for 

practical application of this approach as 

a basis for developing national 

standards to protect sensitive U.S. 

ecosystems from adverse effects related 

to PM deposition.’’ The 2005 Staff Paper 

for the PM NAAQS, in reaching this 

conclusion, addressed various 

important factors, including (1) the lack 

of a long-term, historic database of 

annual speciated PM deposition rates to 

establish relationships between PM 

deposition and ecosystem responses; 

(2) uncertainty in predicting the amount 

of PM deposited to sensitive receptors 

from measured concentrations of PM in 

the ambient air; and (3) the unique 

nature of each ecosystem and the 

current inability to extrapolate with 

confidence any effect from one 

ecosystem to another. The 2005 Staff 

Paper recommended that EPA give 

serious attention to the critical load 

concept and recommended the 

collection of data from a ‘‘greater variety 

of ecosystems over longer time scales to 

determine how ecosystems respond to 

different loading rates over time.’’ 2005 

Staff Paper at page 7–19. 

The review of the secondary NAAQS 

for NOX and sulfur oxides (SOX), which 

is currently underway, is evaluating 

ecological effects due to the atmospheric 

deposition of NOX and SOX. The two 

main targeted effects are acidification 

and nutrient enrichment in both aquatic 

and terrestrial ecosystems. This review 

is attempting to use critical loads to 

evaluate the impact of current 

depositional loads and alternative loads 

in several case study areas. However, as 

mentioned earlier, the estimation of 

ecosystem critical loads expressed in 

terms of PM requires long-term 

ecosystem-level data on speciated PM 

deposition rates for which an adequate 

database is currently lacking for most 

sites in the United States. 

The environmental group commenter 

also asserted that the safe harbor 

increments would allow PM2.5 air 

quality to deteriorate to the level of the 

NAAQS in many locations. According 

to the commenter’s analysis, at 55 

percent of the locations with PM2.5

monitors that were not already 

exceeding the PM2.5 NAAQS, 24-hour 

PM2.5 concentrations would be allowed 

to increase up to the level of the 

NAAQS. In addition, the analysis 

showed that for 84 percent of locations 

not already exceeding the NAAQS, the 

24-hour PM2.5 concentrations would be 

allowed to increase to a level of 30 μg/ 


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18The commenter cited http://www.nps.gov/ 

shen/naturescience/visibility_and_haze.htm for 

historic visibility in national parks. 

m3 or more. The commenter believes 

that allowing such levels would not be 

protective of public health, given that 

we stated in the 2007 NPRM that we 

had previously found that PM2.5

concentrations less than a range of 30– 

35 μg/m3 (24-hour average) were 

protective of public health (citing 72 FR 

54128). 

The environmental group 

commenter’s analysis showed similar 

results for the proposed annual PM2.5

increments. The commenter asserted 

that PM2.5 concentrations would be 

allowed to increase up to the level of the 

annual NAAQS in 55 percent of the 

locations that are currently in 

attainment, and that 87 percent of these 

sites would be allowed PM2.5

concentrations of 12 μg/m3 or higher. 

Again, the commenter believes that 

allowing annual concentrations at or 

above 12 μg/m3 would not be protective 

of public health, based on our statement 

in the 2007 NPRM that we had 

previously found that PM2.5

concentrations less than a range of 12– 

15 μg/m3 (annual average) were 

protective of public health (citing 72 FR 

54128). 

We do not believe that increments 

must be set at levels that ensure that the 

full amount of increment will be 

available in all locations. The statutory 

provisions in the PSD program have 

always been clear that a source must 

demonstrate that it will comply with 

both the NAAQS and increments for any 

pollutant. Consistent with congressional 

intent, the PSD program does not allow 

a source to violate the NAAQS just 

because its emissions will not cause the 

increments to be exceeded. If the 

increments were to be developed in 

such a way that all areas, taking into 

account current ambient air quality 

status, would be able to utilize the full 

amount of increment, then the 

increment levels would have to be 

unnecessarily stringent in areas that are 

substantially cleaner than levels 

allowed by the NAAQS. 

Congress recognized that all areas of 

the country might not be able to utilize 

the full amount of increment when they 

provided provisions within the Act 

requiring that both the NAAQS and 

increments must continue to be met at 

all times. In areas where the full amount 

of increment is not available due to 

levels of pollution approaching the 

NAAQS, states may need to require 

emissions reductions at existing sources 

to accommodate the desired amount of 

economic growth. Hence, we do not 

believe it is reasonable to unduly 

restrict economic growth in cleaner 

areas by setting more restrictive 

increments to help maintain air quality 

levels below the NAAQS in areas which 

are currently only marginally 

attainment. 

In addition, we disagree with the 

commenter’s assertion that the 

increments will not protect public 

health. In setting the PM2.5 NAAQS at 

35 μg/m3 (24-hour) and 15 μg/m3

(annual), EPA concluded that these 

levels protect public health with an 

adequate margin of safety. Regardless of 

the level at which the increments are 

set, no source is permitted to cause the 

NAAQS to be exceeded. That is, as 

noted previously, the upper bound on 

the permissible concentration of PM2.5 is 

determined by the increment or the 

NAAQS, whichever is more restrictive 

in each particular case. Thus, the entire 

framework of the PM2.5 regulations, 

including the safe harbor increments, is 

protective of public health. In asserting 

otherwise, the commenter has 

misconstrued our statements in this 

regard. 

In the 2007 NPRM section on the 

health effects of PM2.5 (72 FR 54127– 

54128), we discussed the fact that we 

considered setting the 24-hour NAAQS 

in the range of 30 to 35 μg/m3 and the 

annual NAAQS in the range of 12 to 15 

μg/m3. However, we concluded in 

setting the NAAQS that 35 μg/m3 (24- 

hour) and 15 μg/m3 (annual) are 

protective of public health with an 

adequate margin of safety. We did not 

say, nor do we believe, that PM2.5

concentrations must be below 30 μg/m3

(24-hour average) or 12 μg/m3 (annual 

average) to protect public health. 

The environmental group commenter 

believes that there is a quantifiable 

relationship between visibility 

impairment and PM2.5 levels, citing the 

2007 NPRM discussion (72 FR 54135) as 

well as the most recent Criteria 

Document and Staff Paper for PM2.5. The 

commenter pointed out that in the 2007 

NPRM (72 FR 54135), EPA observed that 

the proposed Class II short-term safe 

harbor increment of 9 μg/m3, if 

combined with the estimated daily 

background levels in most areas (i.e., 10 

μg/m3), would be below the minimum 

values recommended in the 2005 Staff 

Paper for the secondary short-term 

standard for PM2.5 (which was 20 μg/ 

m3). Rather than supporting the 

adequacy of 9 μg/m3 as an increment 

level to protect visibility, the 

commenter believes that this shows that 

the safe harbor increment is inadequate 

because consumption of an increment of 

9 μg/m3 combined with background 

levels alone would cause an area to 

reach within 1 μg/m3 of the staffrecommended value of 20 μg/m3. The 

commenter added that most areas would 

have PM2.5 pollution from motor 

vehicles and stationary sources in 

concentrations substantially greater than 

background levels, easily placing these 

areas above 20 μg/m3 (citing the 2005 

Staff Paper at 2–77). 

The environmental group commenter 

went on to assert that the safe harbor 

PM2.5 increments will not be sufficient 

to protect visibility in parks and other 

natural areas. In the 2007 NPRM, we 

stated that a 24-hour average PM2.5

concentration of 20 μg/m3 correlates to 

a visual range of approximately 25 to 35 

kilometers. 72 FR 54129. The 

commenter asserted that this visual 

range distance falls far short of what the 

National Park Service considers to be 

good visibility for national parks, 

adding that the National Park Service 

has stated that visibility used to be 90 

miles (145 km) on average in eastern 

parks, and 140 miles (225 km), on 

average in western parks.18 The 

commenter stated that the safe harbor 

increments would allow parks and other 

natural areas to experience PM2.5

pollution that is correlated with a 

25–35 km visual range. 

The visibility impairment issue is 

more complex than suggested by the 

environmental group commenter. In 

addition to predicting what the 

maximum ambient change in air quality 

is for a particular area, a visibility 

impairment assessment considers such 

things as the frequency, magnitude, and 

duration of visibility impacts in order to 

conclude that an adverse impact will 

occur. 

In addition, the environmental group 

commenter misconstrued the 

illustration we included in the 2007 

NPRM. We noted that the lowest level 

we considered as a secondary PM2.5

NAAQS was 20 μg/m3, which was 

considered to address visibility issues in 

urban areas. We also noted that in most 

areas, the estimated 98th percentile of 

daily background concentrations is less 

than 10 μg/m3. In adding the Class II 

safe harbor increment (9 μg/m3) to the 

98th percentile of background levels, we 

were simply showing that even in the 

worst case, the combination of the safe 

harbor increment and background PM2.5

would not exceed the most stringent 

level we considered for the secondary 

PM2.5 NAAQS. The commenter 

presented this rough, worst-case 

calculation as if it represented the 

typical situation that would result from 

the safe harbor increments. In addition, 

the environmental group commenter’s 

statements do not apply to parks and 

special areas that are classified as Class 


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I areas because the safe harbor 

increments for such areas are much 

lower. 

Another commenter stated that the 

proposed 24-hour Class I increment (2 

μg/m3) would not be protective of 

AQRVs, particularly visibility. This 

commenter noted that the National Park 

Service uses a 5 percent change in light 

extinction from estimated natural 

conditions as the threshold for ‘‘adverse 

impacts’’ to Class I visibility. The 

commenter indicated that depending on 

the constituents of the ambient PM2.5

and the humidity, a concentration of 2 

μg/m3 in a typical Class I area would 

result in a change in light extinction 

ranging from 13 to 80 percent in the 

Western United States and from 8 to 50 

percent in the Eastern United States 

and, therefore, would likely constitute 

‘‘adverse impacts’’ to Class I visibility. 

While acknowledging that the FLM may 

still determine that the visibility in the 

Class I area is adversely affected by an 

increase in concentration that is less 

than the increment, this commenter 

pointed out that we stated in the 2007 

NPRM that ‘‘generally speaking an 

increment should not be so large that it 

routinely results in substantially more 

pollution in Class I areas than is 

generally acceptable under the AQRV 

approach’’ (citing 72 FR 54135). The 

commenter concluded that the proposed 

24-hour PM2.5 increment does not meet 

this test and recommended that EPA set 

a lower PM2.5 24-hour increment. 

This commenter appears to have 

identified a worst-case scenario in terms 

of increment concentrations, and 

although we agree with the visibility 

impacts related to those concentrations 

discussed in the comment, we do not 

believe the proposed increment level 

compromises the protection of visibility 

or other AQRVs. Although the ‘‘AQRV 

test’’ uses 5 percent light extinction as 

a screening threshold, the determination 

of adverse impact is made on a case-bycase basis taking into account the 

geographic extent, intensity, duration, 

frequency, and time of visibility 

impairment and how these factors 

correlate with visitation to the Class I 

area. The suggestion that the 5 percent 

threshold is routinely exceeded by PSD 

sources or that an absolute worst-case 

scenario is occurring to the geographic 

extent, intensity, duration, and 

frequency that would warrant an 

adverse impact determination is 

unsupported, especially considering the 

relatively few adverse impact 

determinations that have been made in 

the past. It is, however, important to 

note that the AQRV analysis is 

independent of the PSD increment 

analysis; whether or not the increment 

is projected to be exceeded does not 

determine the need for an AQRV 

analysis. The determination that a 

facility does or does not cause an 

adverse impact on a Class I area is not 

solely contingent upon the PSD 

increment, so we do not believe that 

lowering the proposed increment is 

necessarily more protective of the 

AQRV. 

With respect to these two 

commenters’ concerns about visibility 

protection, we continue to believe that 

the increments cannot be expected to be 

the sole means of protecting various 

welfare concerns. In the 2007 NPRM, we 

stated that ‘‘visibility protection in Class 

I areas is more adequately provided by 

the AQRV process.’’ Congress defined 

AQRVs to specifically include visibility 

and left it for the FLMs to define other 

special attributes of Class I areas that 

warranted special protection. We also 

noted that Congress has established 

several visibility programs that target 

emissions reductions to achieve desired 

visibility benefits. See 72 FR 54135. 

Collectively, these protective programs, 

along with the totality of the PSD 

program, offer an effective means of 

addressing unique local problems that 

cannot be addressed solely by uniform 

national increments. 

However, the environmental group 

commenter asserted that these other 

programs will not fulfill the statutory 

purposes. As discussed previously in 

sections V.D.4 and 5, the commenter 

does not believe that FLM review in the 

AQRV process and the air quality 

impacts analysis required by section 

165(a) of the Act are adequate. We 

disagree; see sections V.D.4 and 5 for 

more detail on the comments and our 

responses. 

The environmental group commenter 

also noted that we cited the regional 

haze program as a justification for 

adopting less protective PSD rules 

(referring to 72 FR 54135), but the 

commenter pointed out that the haze 

program applies only to Class I areas 

and does not apply at all to the majority 

of the nation, which is Class II. The 

commenter further noted that we stated 

in the 2007 NPRM that ‘‘some State and 

local governments have also developed 

programs to improve visual air quality 

in specific urban areas’’ (citing 72 FR 

54135), and pointed out that we gave no 

specific information on such programs, 

nor any information about the visibility 

protection that they provide beyond that 

provided by the proposed increments. 

The commenter asked that we identify 

the specific State and local programs, 

and that we specify how much visibility 

protection such programs are providing. 

The commenter is correct that the 

regional haze program directly 

addresses only Class I areas. As we have 

discussed before, these are the areas that 

Congress defined as deserving of the 

most protection under PSD, including 

the visibility protection provisions in 

subpart 2 of title I, part C of the Act, 

which is the statutory basis for the 

regional haze program. While Class I 

areas are the target for the regional haze 

program, we believe that many areas of 

the nation will receive collateral 

visibility benefits from this program. As 

emissions of the pollutants that cause 

regional haze are reduced, many areas 

in the paths of transport will benefit. In 

addition, as discussed previously in 

section V.D.5 of this preamble, PSD 

applicants must prepare an analysis of 

‘‘other impacts,’’ including visibility 

impacts, in areas other than Class I 

areas. 

Regarding State and local visibility 

programs, in the 2005 Staff Paper EPA 

described several existing programs to 

improve visual air quality in urban 

areas. These programs were located in 

Denver, CO; Phoenix, AZ; and Lake 

Tahoe, CA. Also, the states of California 

and Vermont have each established 

standards to protect visibility. See the 

2005 Staff Paper, pages 6–17 through 

6–23. 

The environmental group commenter 

cited the 2007 NPRM (72 FR 54135) 

where we said that the use of ‘‘distinct 

PM increments for visibility protection 

is not the most effective means of 

addressing the visibility problem.’’ The 

commenter believes that this claim is 

based on false premises, including the 

idea (discussed previously) that other 

programs effectively protect visibility 

nationwide, and the idea that the only 

option is a ‘‘distinct’’ PM increment for 

visibility protection. As to the latter, the 

commenter stated that EPA can 

strengthen the safe harbor increment to 

ensure visibility protection and need 

not adopt a separate ‘‘visibility’’ 

increment. In addition, the commenter 

asserted that EPA has ignored the 

statutory mandate that the PSD rules 

fulfill the statutory goals and purposes, 

and that we cannot shirk that statutory 

duty merely because we claim some 

other type of action would be ‘‘more 

effective.’’ 

We continue to believe that Class I 

area visibility protection under the PSD 

program is appropriately addressed via 

the AQRV process. As mentioned 

previously, Congress explicitly included 

‘‘visibility’’ as an AQRV for which FLMs 

would have an affirmative responsibility 

to protect in Class I areas under their 

jurisdictions. Where the FLM 

successfully demonstrates that there 


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would be an adverse impact on the 

AQRV (e.g., visibility), a State cannot 

issue a PSD permit, even when the 

source’s emissions do not violate the 

PM2.5 increments. In addition, we 

continue to believe that the analysis of 

other impacts, including visibility, in 

non-Class I areas is the appropriate 

means of addressing visibility 

protection in these areas, as envisioned 

by Congress when it enacted the PSD 

provisions of the Act. 

As a result, we do not believe it is 

necessary to create a distinct increment 

(e.g., with a different averaging period) 

or to lower the safe harbor increments 

to protect visibility in urban, non-urban, 

or Class I areas across the United States. 

We reach this conclusion in proper 

consideration of the other, more direct 

approaches being used to address 

visibility problems in the United States. 

The primary such approach, the 

regional haze program, is within the 

PSD framework for PM2.5. Note that part 

C of title I of the Act, ‘‘Prevention of 

Significant Deterioration of Air Quality,’’ 

includes subpart 2, which is the 

statutory basis for the regional haze 

program. Regarding our consideration of 

other State and local visibility 

protection measures that are outside the 

PSD framework, we do not believe it is 

reasonable to disregard these areaspecific measures that focus on the 

preferences of individual communities 

where a uniform national increment for 

visibility protection generally cannot. 

The environmental group commenter 

also stated that the proposed PSD rules 

fail to ensure fulfillment of the 

‘‘enhancement goal’’ set out in the Act. 

The commenter noted that section 

101(a) states as the Act’s first purpose: 

‘‘to protect and enhance the quality of 

the Nation’s air resources,’’ while 

section 160(2) states that the purpose of 

the PSD program is to ‘‘preserve, protect, 

and enhance’’ air quality in parks and 

other special areas. The commenter 

asserted that the proposed rule did not 

address these enhancement 

requirements or explain how the 

proposed increments would fulfill those 

requirements. 

This same issue was raised in the 

2005 PSD rule affirming the NO2

increments. At that time we expressed 

our belief that the goal to enhance air 

quality in national parks and wilderness 

areas is implemented through the 

regional haze program while the PSD 

program focuses on preserving and 

protecting air quality in these areas. 

However, when a PSD increment 

violation is identified, we agree that 

EPA may require a State to revise its SIP 

to correct the violation. See 40 CFR 

51.166(a)(3). Otherwise, we do not 

interpret these PSD provisions to 

authorize us to direct states in their SIPs 

to achieve reductions in emissions from 

existing sources for PSD purposes. 

We recognized at that time, and 

continue to believe, that the growth 

management goals of PSD may also be 

fulfilled when the states adopt controls 

on existing sources that would reduce 

emissions and allow growth from new 

sources and major modifications to 

existing sources without causing 

significant deterioration. Under the 

increment approach, we have 

interpreted the PSD rules to allow states 

to require reductions from existing 

sources in order to expand the allowable 

increments and, thereby, allow for more 

growth under the PSD program. 

However, we have never required states 

to do so because, in the absence of an 

increment violation, we do not believe 

section 166 and other provisions in part 

C of title I of the Act give us the legal 

authority to mandate such reductions 

for PSD purposes. 

Another commenter stated that the 

PM2.5 increments should be twice the 

recommended levels because scientific 

studies do not support the need for such 

low levels for protection of health and 

welfare. The commenter believes that 

increments at the proposed levels would 

jeopardize the goal of providing 

opportunities for economic growth. The 

commenter expressed concern over 

EPA’s use of epidemiologic studies and 

questioned the ability of such studies to 

provide a reliable evaluation of health 

risks. The commenter claimed that 

epidemiologic studies are capable of 

finding association between a substance 

or exposure and a health effect but 

rarely capable of determining if there is 

causation, while toxicological studies 

using randomized trials are specifically 

designed to determine causation. The 

commenter added that other factors 

providing evidence for causation 

include dose-response relationships, 

consistency, and repeatability of 

studies, which the commenter said are 

not present in the studies cited by EPA. 

The commenter specifically referred to 

two studies, acknowledged by EPA to 

show no evidence of a dose-response 

relationship gradient between PM2.5 and 

specific health related effects. 

We disagree with the commenter’s 

recommendation that the increments 

should be twice the proposed (and final) 

levels. The scientific studies to which 

the commenter referred pertain to 

studies that EPA used to determine the 

health-based NAAQS for PM2.5, and we 

do not believe it is relevant to this rule 

to respond to comments related to the 

setting of the NAAQS. The NAAQS are 

designed to protect public health and 

welfare; increments then are intended to 

insure that air quality in clean areas is 

not allowed to deteriorate significantly, 

and the PSD regulations insure that any 

such deterioration does not lead to air 

pollution levels that exceed the levels 

defined by the NAAQS. 

As discussed previously, we are 

finalizing this rulemaking using the safe 

harbor approach under section 166(a) of 

the Act. Using this approach, we 

calculated the ‘‘safe harbor’’ increments 

as percentages of the NAAQS 

comparable to the percentages that 

Congress used to establish the original 

statutory increments for PM and SO2. 

These values represent the level of 

effectiveness necessary to satisfy section 

166(d) of the Act, and could be 

tightened if necessary based on further 

analysis to determine if additional 

measures are necessary to fulfill the 

requirements of section 166(c) of the 

Act. Thus, under this approach and on 

this record, we do not conclude that it 

is appropriate to finalize increments at 

levels any less stringent than the safe 

harbor increments, as the commenter 

recommends. 

7. Compliance Determinations for the 

PM2.5 Increments 

a. Modeling Compliance With PM2.5

Increments 

Section 163(a) of the Act provides that 

‘‘In the case of any maximum allowable 

increase * * * for a pollutant based on 

concentrations permitted under the 

national ambient air quality standards 

for any period other than an annual 

period, such regulations shall permit 

such maximum allowable increase to be 

exceeded during one such period per 

year [emphasis added].’’ Accordingly, 

the existing PSD rules allow one 

exceedance per year of each short-term 

increment defined by the rules. See 40 

CFR 51.166(c) and 52.21(c). With the 

addition of the PM2.5 increments to the 

list of maximum allowable 

concentrations in the PSD rules, the 

existing provision allowing one 

exceedance per year applies equally to 

the 24-hour PM2.5 increments as well. 

Thus, when modeling increment 

compliance, the highest value of the 

second-highest modeled increase in 

estimated PM2.5 concentrations at each 

model receptor for the 24-hour 

averaging time should be less than or 

equal to the maximum allowable 

increase for PM2.5. For the annual 

increments, the modeled annual 

averages should not exceed the annual 

maximum allowable increase for PM2.5. 

See EPA’s ‘‘Guideline on Air Quality 

Models’’ at 40 CFR part 51 appendix W, 

section 10.2.3.3. 


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19We proposed test methods for measuring PM10

and PM2.5, including condensable PM emissions, 

from stationary sources on March 25, 2009 (74 FR 

12970). In the same notice, we sought comments on 

whether to end the NSR transition period for 

condensable PM earlier than January 1, 2011. We 

anticipate publication of a final rule announcing 

our decision on the NSR transition period in July 

2010. 

We did not expressly state in the 2007 

NPRM the implications of adding PM2.5

increments to the existing list of 

increments in 40 CFR 51.166(c) and 

52.21(c) of the PSD regulations. 

Nevertheless, it should have been clear 

at the time that, in the absence of 

alternative language for PM2.5, the 

existing provision allowing one 

exceedance for the short-term 

increments would apply to the 

increments for PM2.5 along with the 

increments already listed. We did not 

receive any comments either supporting 

or opposing these methods for 

determining compliance with the PM2.5

increments. 

We recognize that the above approach 

for determining compliance with the 24- 

hour PM2.5 increments differs from the 

approach contained in guidance that we 

provided in a March 23, 2010 memo 

titled ‘‘Modeling Procedures for 

Demonstrating Compliance with PM2.5

NAAQS,’’ which sets forth a procedure 

designed to demonstrate compliance 

with a statistically based standard that 

is met when the 98th percentile 24-hour 

concentration is less than or equal to 

35 ug/m3. A similar dichotomy exists for 

the 24-hour PM10 increments and 

NAAQS, where compliance with the 24- 

hour PM10 NAAQS is based on an 

expected exceedance form of the 

standard. 

b. Condensable PM 

Initially, the EPA will not require PSD 

applicants under the Federal PSD 

program to consider condensable PM in 

emissions calculations to determine 

whether a proposed project is subject to 

the PSD requirements. In addition, we 

will not require the condensable portion 

to be considered in the required PM2.5

air quality analyses. In our May 2008 

PM2.5 NSR Implementation Rule, we 

announced that we would not require 

that states address condensable PM in 

establishing enforceable emissions 

limits for either PM10 or PM2.5 in NSR 

permits until the completion of a 

transition period. Further, we indicated 

that the transition period would end 

January 1, 2011 unless EPA advanced 

the date through the rulemaking 

process. We also indicated that such 

rulemaking would involve the 

assessment and possible revision of test 

methods for measuring condensable 

emissions and taking comment on an 

earlier closing date for the transition 

period in the NSR program if we are on 

track to meet our expectations to 

complete the test methods rule much 

earlier than January 1, 2011.19 In 

addition, states that have developed the 

necessary tools are not precluded from 

acting to include condensable PM 

emissions in NSR permit actions prior 

to the end of the transition period, 

especially if it is required in an 

applicable SIP. See 73 FR 28334–28336. 

c. PM2.5 Precursors 

In the 2007 NPRM, we proposed to 

add SILs for PM2.5 to the PSD 

regulations at 40 CFR 51.166 and 52.21. 

(The SILs are described more fully in 

section VI of this preamble.) 

Accompanying these SILs, we proposed 

to add a new paragraph to the 

regulations explaining that the 

requirements for a source impact 

analysis for PM2.5 would be considered 

to be satisfied, without further air 

quality modeling, if it were to be shown 

that the increase in direct PM2.5

emissions from the source or 

modification will cause air quality 

impacts less than the prescribed SILs for 

PM2.5. The reasoning at the time was 

that state-of-the-art modeling would not 

be available to adequately account for 

secondary PM2.5 impacts resulting from 

emissions of precursors of PM2.5, e.g., 

SO2 and NOX. Nevertheless, the existing 

PSD rules currently define potential 

precursors of PM2.5. Based on the 

proposed language, the required 

compliance demonstration for the PM2.5

NAAQS and the PM2.5 increments 

(when promulgated) would be limited 

by regulation to an analysis of direct 

PM2.5 emissions, and would not include 

consideration of emissions of PM2.5

precursors for comparing the modeled 

source impacts to the prescribed SILs 

for PM2.5. 

The impacts of PM2.5 precursors on 

ambient concentrations of PM2.5 cannot 

be determined from the dispersion 

models that EPA has currently approved 

for modeling individual PSD sources. 

Such models are not designed to 

consider chemical transformations that 

occur in the atmosphere after the 

precursor emissions have been released 

from the source. Consideration of these 

transformations is necessary to be able 

to add precursor impacts into the total 

modeled ambient PM2.5 concentrations 

for comparison to the SILs for PM2.5. 

The technical tools needed to 

complete a comprehensive analysis of 

all emissions that contribute to ambient 

concentrations of PM2.5 are only in the 

developmental stage; nevertheless, we 

believe that it would be inappropriate to 

restrict the regulatory language in such 

a way that future regulatory 

amendments would be required to 

enable the inclusion of precursor 

impacts in the PM2.5 analysis as the 

necessary technical tools become 

available. Estimating techniques are 

being developed that will be able to be 

applied to the PM2.5 analysis in the near 

future, which could not be required if 

the regulatory language precluded them. 

We acknowledge the concerns that have 

been expressed by some commenters 

about the shortcomings of not 

considering the impacts of PM2.5

precursors under the PM2.5 air quality 

analyses. Accordingly, we believe that 

the new provision for applying the SILs 

for PM2.5 to the required analyses for the 

NAAQS and increments should not be 

self-limiting by specifying the use of 

only direct PM2.5 emissions. Instead, the 

new provision contained in this final 

rule provides that the test will be based 

on whether ‘‘the emissions increase 

* * * would cause * * * air quality 

impacts less than [the PM2.5 SILs].’’ See 

new 40 CFR 51.166(k)(2) and 

52.21(k)(2). We believe that it would be 

more effective to rely on interim policy 

and guidance as appropriate to help 

determine the best methods available to 

make the required assessment of source 

impacts on ambient PM2.5 resulting from 

any emissions. 

F. Final Action on Trigger and Baseline 

Dates for PM2.5 Increments 

In the 2007 NPRM, we proposed as 

part of Option 1 to require the 

implementation of the PM2.5 increment 

system (annual and 24-hour increments) 

with new baseline areas, baseline dates, 

and trigger date. Specifically, we 

proposed that the major source baseline 

date and trigger date, both fixed dates, 

would be defined as the effective date 

of the final rule and would reflect a date 

1 year from the date of promulgation, in 

accordance with section 166(b) of the 

Act. In contrast, under Option 2 (both 

2A and 2B), we proposed to establish 

new baseline dates for the 24-hour PM2.5

increments, but to retain the existing 

baseline areas and dates for the annual 

PM2.5 increments because the annual 

increments would be equivalent 

substitutes for the existing annual PM10

increments. 

In light of the then-current and 

expected trends in PM2.5 concentrations, 

our judgment was that starting with new 

baseline dates on or after the effective 

date of this rule would make the PSD 

increments for PM2.5 more protective. 

We proposed that any emissions 

reductions occurring prior to the 

effective date of this rule would lower 


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the baseline concentration rather than 

be used for expanding the PM2.5

increment. If a retroactive baseline date 

were to apply, emissions reductions 

occurring prior to the effective date of 

this rule would serve to expand the 

available increments, enabling more 

new pollution than would otherwise be 

allowed to occur. 

We also expressed our belief that 

starting with different baseline dates to 

implement increments for PM2.5 would 

be appropriate because Option 1 treats 

PM2.5 essentially as a ‘‘new’’ pollutant 

for purposes of PSD and section 166 of 

the Act. We continue to believe that 

establishing a new baseline also 

overcomes significant implementation 

concerns that would otherwise exist if 

the existing PM baseline were 

maintained. In particular, if we were to 

require sources and reviewing 

authorities to conduct PM2.5 increment 

analyses based on the minor source 

baseline dates previously established 

years or even decades ago under the 

TSP or PM10 program, they would have 

to attempt to recreate the PM2.5

emissions inventory as of the minor 

source baseline date in order to 

determine the baseline PM2.5

concentration for the area. For early 

minor source baseline dates in 

particular (e.g., 1976 in some areas of 

the United States), establishing the 

emissions inventory for PM2.5 would be 

extremely difficult, cumbersome, and 

potentially inaccurate because historic 

emissions inventories did not include 

PM2.5 emissions. For all of these 

reasons, we proposed Option 1 as our 

preferred option and requested 

comment on this contingent safe harbor 

approach for annual and 24-hour PM2.5

increments under Option 1. 

Under Option 1, we proposed that the 

PM2.5 increments would be subjected to 

a 1-year delay consistent with the 

procedures under section 166(b) of the 

Act, which provides in general that 

these rules ‘‘shall become effective one 

year after the date of promulgation.’’ 

Alternatively, we sought comment on a 

60-day delay as part of our proposal 

under Option 1. In the proposal we 

requested comment on the argument 

that, while the Act includes a 1-year 

implementation delay for new 

increments, the same provision calls for 

EPA to promulgate new increments 

within 2 years of the promulgation of 

the NAAQS. Given that these PM2.5

increments are being promulgated more 

than 2 years after promulgation of the 

NAAQS, we expressed our belief that 

the overall congressional intent 

reflected in section 166 of the Act could 

possibly be met by setting the effective 

date of the PM2.5 increments earlier than 

the ‘‘one year after the date of 

promulgation’’ provided in section 

166(b) of the Act. 

Twelve commenters supported our 

proposal under Option 1 to establish 

new trigger and baseline dates for PM2.5, 

regardless of the particular increment 

option that they otherwise supported. 

These commenters generally saw new 

dates as being the best approach because 

of various problems that would result 

from retaining existing trigger and 

baseline dates. Some commenters 

claimed that it would be technically 

difficult to try to reconstruct old 

inventories to determine the amount of 

PM2.5 emitted by sources in the past. 

One commenter stated that 

establishing PM2.5 increment 

inventories using existing PM10 baseline 

dates would be ‘‘extremely difficult, 

cumbersome, and necessarily inaccurate 

and unreliable as historic emissions did 

not speciate PM2.5 emissions.’’ A State/ 

local agency commenter said that it 

would be ‘‘virtually impossible for 

States to calculate the PM2.5 component 

of previously consumed PM10

increments because data on the fine and 

coarse fractions of source emissions are 

largely unavailable.’’ 

Yet another commenter claimed that 

‘‘resurrecting PM2.5 inventories based on 

the PM10 baseline dates would be 

insurmountable.’’ Similar comments 

were echoed by several commenters 

who supported the use of legal authority 

set forth in section 166(f) (‘‘equivalent 

substitution’’ approach) for developing 

the numerical values for the PM2.5

increments. One of these commenters 

stated that he did not ‘‘believe the 

establishment of new baseline dates for 

PM2.5 would abandon past cases of 

increment consumption for PM10, 

because the 24-hour PM10 increments 

would still be in effect * * *.’’ 

One commenter suggested that ‘‘EPA 

establish the trigger date as of the date 

when it officially established the nonattainment and attainment areas for 

PM2.5; that is, April 5, 2005.’’ The 

commenter explained that this approach 

is consistent with the PSD regulations 

from their inception and partially 

mitigates EPA’s delays in implementing 

the PSD program for PM2.5. The 

commenter believes ‘‘that States should 

be required to use the baseline areas 

previously established for their PSD 

program, unless the process for 

redefining these areas strictly follow 

procedures in the PSD regulations and 

EPA policy.’’ The commenter claimed, 

‘‘this will minimize any inconsistent 

applications of the regulations for 

PM2.5.’’ 

One commenter noted that our 

proposed PM2.5 increments were very 

low and ‘‘facilities may find themselves 

immediately out of compliance with the 

PM2.5 increments upon promulgation of 

the rule, based on a January 1975 or 

1977 baseline date.’’ 

One commenter indicated that the 

historic TSP/PM10 baseline dates should 

be retained. This commenter favored the 

equivalent substitution approach under 

section 166(f) and, consistent with that 

approach, retention of the existing 

baseline dates. 

Having considered all the comments, 

we believe that the most reasonable 

approach for addressing the relevant 

dates associated with the PM2.5

increments is to start anew with the 

baseline date concept. As already 

mentioned, the commenters have 

identified difficulties that would occur 

if the PM2.5 emissions inventory for 

increment analyses had to be created for 

an earlier period of time, and the 

existence of these difficulties supports 

the approach under Option 1 to 

establish new dates for implementing 

the PM2.5 increments. Also, these new 

baseline dates for PM2.5 increments will 

not undo the current protection 

provided by the existing increments for 

PM because we are not revoking the 24- 

hour or annual PM10 increments under 

this new rule. Accordingly, this final 

rule establishes independent PM2.5

increments using a ‘‘trigger date’’ and 

‘‘major source baseline date’’ that are 

separate from the dates defined for the 

PM10 increments. Consequently, new 

minor source baseline dates and the 

corresponding baseline areas will be 

used for the annual and 24-hour PM2.5

increments, and will be established 

when a source applies for a PSD permit 

any time on or after the new trigger date 

for PM2.5. (See also the discussion about 

changes to the definition of ‘‘baseline 

area’’ in section V.G of this preamble.) 

The ‘‘major source baseline date’’ for 

PM2.5 is being set as October 20, 2010— 

the date of publication of this final rule. 

The setting of this date differs from 

previous major source baseline dates 

which were set as the date of 

publication of the proposed rule, but is 

similar to the major source baseline date 

set for the other increments in that the 

date precedes the effective date for 

implementing the increments, and 

thereby requires that certain major 

source emissions increases that occur 

before the trigger date retroactively 

count toward the amount of increment 

consumed. 

The ‘‘trigger date’’ is being set at 

October 20, 2011, which is 1 year after 

the date of promulgation of this final 

rule. We are using this approach to 

define the date on which the PM2.5

increments become effective as 1 year 


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20 ‘‘A source will be considered to impact an area 

if it has an impact of 1 μg/m3 or more of SO2 or 

PM on an annual basis. This figure has been 

selected because it corresponds to levels of 

significance used in previous Agency 

determinations for SO2 and PM. 45 FR 52716. 

from the date of publication, consistent 

with the 1-year delay required under 

section 166(b) of the Act. This date for 

the ‘‘trigger date’’ separates the 

applicability date of the PM2.5

increments from the effective date of 

this final rule in general, but also 

ensures that the ‘‘minor source baseline 

date’’ for PM2.5 for any particular PM2.5

attainment or unclassifiable area cannot 

be established until after the increments 

become effective in this final rule. The 

implementation of these dates as part of 

the PM2.5 increment system is discussed 

in greater detail in section VIII of this 

preamble. 

We recognize that some may still have 

a concern about our decision to set the 

major source baseline date as the date of 

publication of this final rule in light of 

the fact that the PM2.5 NAAQS have 

been in place since 1997; however, we 

believe that the selection of possible 

earlier dates would require states to 

retroactively establish PM2.5 emissions 

inventories for increment analyses 

during a period when sources were 

generally not required to conduct PM2.5

air quality analyses. Hence, given the 

lack of information, and considering the 

technical difficulties in doing so, we do 

not believe that it would be appropriate 

to require states and sources to 

retroactively account for PM2.5

increment consumption by setting the 

major source baseline date at an earlier 

date than the date we have selected. 

G. Definition of ‘‘Baseline Area’’ for 

PM2.5

No changes were proposed with 

respect to the definition of ‘‘baseline 

area’’ for PM2.5 increments. One 

commenter, however, noted that fact in 

claiming that we did not adequately 

account for significant impacts of PM2.5

for purposes of defining the ‘‘baseline 

area’’ for the PM2.5 increments. Under 

the existing regulations, the 

establishment of a baseline area for any 

PSD increment results from the 

submittal of the first complete PSD 

application, and is based on both the 

location of the proposed source and the 

impact of the source’s emissions on the 

area. In accordance with the definition, 

the attainment or unclassifiable area in 

which the proposed source would 

construct is always part of the baseline 

area in which the minor source baseline 

date is established and the increment 

analysis is conducted. In addition, the 

definition provides that any 

surrounding attainment or 

unclassifiable area in which the 

proposed source’s impact is greater than 

1 μg/m3, annual average, would also 

become part of the baseline area, 

assuming the area had not already been 

established as a baseline area by a 

previous application for a PSD permit. 

See 40 CFR 51.166(b)(15) and 

52.21(b)(15). 

As explained in the preamble for the 

1980 PSD regulations, EPA selected an 

impact of 1 μg/m3, annual average, for 

the definition of ‘‘baseline area’’ because 

that value was considered the level of 

significance for both SO2 and PM when 

the definition was originally 

established.20 There was no mandate at 

that time that a 1 μg/m3 impact be used 

to determine the baseline area for 

increments for other pollutants; 

however, the use of a 1 μg/m3 impact in 

the definition of ‘‘baseline area’’ was not 

changed when EPA developed 

increments for NO2 in 1988 because 

EPA also defined ‘‘significant’’ for NO2

using the same annual average 

concentration of 1 μg/m3. The EPA has 

determined, however, that ‘‘significant’’ 

for PM2.5 ambient impacts should be 

considered to occur at a lower 

concentration than 1 μg/m3. Elsewhere 

in this preamble, we have indicated that 

the SIL for PM2.5 in this final rule is 0.3 

μg/m3, annual average. Consequently, 

although no change to the definition of 

‘‘baseline area’’ was proposed in this 

rule, we believe it is necessary and 

appropriate to define in this final rule 

a level of significance of 0.3 μg/m3, 

annual average, for establishing a new 

baseline area for purposes of PM2.5

increments. See revised 40 CFR 

51.166(b)(15)(i) and 52.21(b)(15)(i). 

Had we established the SIL at 

1 μg/m3, annual average, as proposed 

under Option 1 for SILs, then the 

definition of ‘‘baseline area’’ would not 

need to be revised. However, the revised 

definition in this final rule is consistent 

with our decision to establish a SIL of 

0.3 μg/m3, annual average, for PM2.5. We 

consider this action to be a logical 

outgrowth of our decision to establish a 

SIL for PM2.5 and the comment 

concerning the effect of that action on 

the definition of ‘‘baseline area.’’ Thus, 

we believe that our failure to initially 

propose this change to the definition of 

‘‘baseline area,’’ based on the possibility 

of selecting Option 3 for defining the 

SIL for PM2.5, does not warrant a 

reproposal. 

H. No Final Action With Respect to the 

Proposed Revocation of PM10 Annual 

Increments 

In the 2007 NPRM, we proposed to 

either revoke or replace the annual 

increments (Class I, II, and III) for PM10

to conform to the earlier revocation of 

the annual PM10 NAAQS. We proposed 

to revoke the annual increments, based 

on the same technical evidence that led 

us to revoke the annual PM10 NAAQS, 

if we decided to use Option 1 for 

adopting PM2.5 increments, and 

discussed our authority and rationale 

for doing so. 72 FR 54136. 

As an alternative, under Options 2A 

and 2B we proposed to replace the 

existing annual PM10 increments with 

equivalent substitute PM2.5 increments 

using the authority under section 166(f) 

of the Act. After further analysis and 

consideration of the comments on this 

issue, we have decided not to take any 

final action on our proposal to revoke 

the existing increments for PM10 as part 

of this rulemaking. The effect of not 

taking final action with respect to the 

PM10 annual increments is to leave 

those increments in place and 

unchanged. 

Three commenters agreed with EPA’s 

proposal to ‘‘adopt the 24-hour and 

annual PM2.5 increments and to revoke 

the annual PM10 increments.’’ One 

commenter stated, ‘‘counting and 

tracking increment is confusing enough 

without adding the confusion of 

potentially overlapping PM standards.’’ 

The commenter noted that the ‘‘cleanest 

approach is to establish a single new 

PM2.5 increment and work from there.’’ 

The commenter suggested that EPA first 

‘‘develop a coarse fraction increment, 

once EPA establishes coarse PM 

NAAQS.’’ The commenter added that 

the removal of the PM10 annual 

increment is supported by the removal 

of the ‘‘health based standard for annual 

PM10.’’ 

One of the commenters agreed, ‘‘it 

makes no sense for EPA’s regulations to 

contain an annual increment for PM10

even though an annual PM10 NAAQS no 

longer exists.’’ The commenter added, 

‘‘EPA is without authority under Section 

166(f) to retain the PM10 annual 

increment if it adopts a PM2.5 annual 

increment.’’ This commenter explained, 

‘‘EPA is compelled by law to eliminate 

the PM10 annual increment.’’ 

We agree with this commenter that 

section 166(f) is a ‘‘substitution’’ 

approach; however, as we stated in our 

2007 NPRM, we expressed some 

concern about using section 166(f) to 

substitute PM2.5 increments for PM10

increments. In fact, some commenters 

challenged our authority under section 

166(f) to replace the PM10 increments. In 

our response to the following 

comments, we address the legal issues 

that we believe prevent us from simply 

revoking the PM10 increments. 


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One environmental commenter 

claimed, ‘‘the agency has no authority to 

repeal an existing PM10 increment 

without at the same time restoring the 

corresponding TSP increment.’’ The 

commenter noted, ‘‘Congress established 

the TSP increments by statute and gave 

EPA no authority to revoke them,’’ and 

‘‘instead, Congress gave EPA only 

limited authority to substitute PM10

increments for TSP increments under 

the conditions specified in Section 

166(f).’’ The commenter explained, ‘‘EPA 

cannot revoke the annual PM10

increments, either by ‘‘replacing’’ them 

with PM2.5 increments or otherwise, 

unless EPA at the same time restores the 

annual TSP increment.’’ The commenter 

noted, ‘‘retention of the PM10 annual 

increment is also entirely compatible 

with the statutory purposes, 

notwithstanding EPA’s revocation of the 

annual PM10 NAAQS.’’ The commenter 

further noted the following examples/ 

evidence that retention of the annual 

PM10 increments is important to 

achieving the goals of the Act’s PSD 

provisions: 

• ‘‘While EPA attributes the visibility 

impairing impacts of PM pollution 

primarily to elevated short term fine 

particle concentrations, EPA recognizes 

that PM10 plays a significant role in the 

other welfare related impacts of PM 

pollution.’’ 72 FR 54136. 

• ‘‘EPA also states that the most 

significant PM-related ecosystem-level 

effects result from long term cumulative 

deposition * * * that exceeds the 

natural buffering or storage capacity of 

the ecosystem and/or affects the 

nutrient status of the ecosystem.’’ 72 FR 

54131. 

Five State/local agency commenters 

opposed the revocation of PM10 annual 

increments ‘‘until EPA makes a 

determination on a PM-coarse NAAQS’’ 

and/or ‘‘establishes equivalent 

increments for PM-coarse.’’ One of these 

commenters added, ‘‘it is prudent to 

maintain the PM10 increments until EPA 

makes a determination on the health 

and environmental effects of the coarse 

fraction of PM.’’ The commenter claimed 

that, ‘‘if EPA retains the annual PM10

increments’’ ‘‘then the determination of 

PM2.5 increments can complement the 

continuation of PM10 increment 

determinations without any 

discontinuities or unwanted 

degradation concerns.’’ 

Another one of these commenters 

stated, ‘‘the basis for dismissing the 

annual PM10 NAAQS by the substitution 

of fine particle NAAQS to address 

certain health and welfare effects does 

not provide a basis for dismissing a PSD 

increment which is meant to stop 

significant degradation of air quality.’’ 

The commenter noted, ‘‘as refinements 

are made to estimation of fine particle 

emissions or in instances where these 

are deemed not to be a major component 

of particulate emissions, the PM10

annual increment could prevent long 

term deterioration of air quality 

associated with the coarse component.’’ 

One State/local agency commenter 

noted, ‘‘EPA also proposes to replace the 

PM10 annual increment with the 

corresponding PM2.5 increment under 

the Section 166(f) options 2A and 2B as 

well, but does not provide a substantive 

basis for such an action.’’ The 

commenter does ‘‘not see the tension 

noted by EPA between Sections 166(a) 

and (f) with respect to reaching a 

holistic solution if EPA views PM2.5 as 

a new indicator of PM, as we believe it 

can.’’ The commenter explained, ‘‘under 

this approach, if EPA determines that 

coarse particle levels are necessary to 

protect the public from certain 

exposures not addressed by PM2.5, then 

it will be appropriate for EPA to define 

complementary increments for coarse 

particulates as another indicator of PM.’’ 

The commenter also asserted that the 

24-hour increments for PM2.5 must be 

based on section 166(f) authority, but 

believes that the PM2.5 increment need 

not replace the PM10 increment for this 

averaging period. 

One commenter requested that EPA 

‘‘keep the PM10 PSD program (especially 

the increments) in place until the full 

PM2.5 program is adopted and in place.’’ 

One commenter ‘‘does not support 

revoking the annual PM10 increments,’’ 

because the commenter feels that ‘‘there 

are too many uncertainties regarding 

PM2.5.’’ The commenter provided the 

following example: ‘‘The program has 

been dragging for years, analytical 

methods are not formulated, the NSR 

part of the implementation rule has not 

issued, condensables are not yet 

included, and the impact of precursors 

has not been definitively explored.’’ The 

commenter explained that ‘‘under these 

conditions, nothing concerning PM10

should be revoked until the reasons for 

doing so are clearly understood and the 

overall impact on ensuring clean air and 

the public health and welfare have been 

fully explored.’’ The commenter 

suggested, ‘‘PM10 increments and 

NAAQS should remain in effect until 

these issues have been resolved to the 

satisfaction of the Administrator.’’ This 

commenter believed that Options 2A 

and 2B must be based entirely on 

section 166(f) of the Act, but that the 

presence of increments for both PM10

and PM2.5 can be supported under this 

section because the two sets of 

increments complement each other. The 

commenter indicated that the problem 

will be resolved when sufficient data are 

available to revoke the PM10 NAAQS 

and increments and/or PM10 is replaced 

by PM10–2.5. 

One State/local agency association 

commenter recommended that ‘‘EPA can 

and should continue both the 24-hour 

and annual average PM10 PSD increment 

program until PM10¥2.5 standards are 

promulgated.’’ The commenter 

explained that ‘‘EPA has the discretion 

to accomplish this under CAA § 166(f)’’ 

and ‘‘at a minimum, the agency should 

continue the 24-hour PM10 increments 

in conjunction with the continuation of 

the 24-hour PM10 NAAQS.’’ 

As stated previously, in this rule we 

are taking no final action on our 

proposal to revoke the annual PM10

increments even though the annual 

PM10 NAAQS has been revoked. Based 

on comments and our own legal 

analysis of the PM10 increments, we 

have concluded that there is a strong 

legal basis for not revoking the annual 

increments at this time. The PM10

increments were promulgated on June 3, 

1993 (58 FR 31622) as replacement 

increments for the then existing 

statutory increments for PM measured 

as TSP. The fact that EPA promulgated 

the PM10 increments as ‘‘equivalent’’ 

replacements for the TSP increments 

under the authority of section 166(f) of 

the Act is important in that EPA does 

not have authority to simply remove the 

TSP increments that were explicitly 

defined within the PSD program 

requirements in the Act. Accordingly, 

we believe that the annual TSP 

increments would be restored by default 

should we decide to revoke the annual 

PM10 increments as proposed. However, 

even if the original annual TSP 

increments were not restored, there is 

no basis for automatically revoking the 

annual PM10 increments simply because 

we have revoked the annual PM10

NAAQS, because annual increments are 

not contingent upon the existence of 

annual NAAQS. This is clear from the 

court’s decision in the earlier NO2

increment litigation stating that 

increments for a particular pollutant do 

not necessarily need to match the 

averaging periods that have been 

established for NAAQS for the same 

pollutant. EDF v. EPA, at 189–190 

(‘‘* * * the ‘goals and purposes’ of the 

PSD program, set forth in § 160, are not 

identical to the criteria on which the 

ambient standards are based.’’). 

I. Other Comments on Increments 

Ten commenters (including State/ 

local agencies and industry 

commenters) supported section 166(f) of 

the Act as the basis for PM2.5

increments. These commenters typically 


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voiced the belief that when Congress 

enacted section 166(f), it authorized 

EPA to update PM increments when 

another indicator was defined, and that 

section 166(f) allows EPA to continue 

do so as long as these increments are of 

equal stringency to the prior increments. 

Some of these commenters believe that 

section 166(f) is the only legitimate 

approach under the Act, while others 

indicated simply that it is preferable to 

section 166(a). Some of the commenters 

believe that section 166(f) authority can 

be used to add PM2.5 increments to the 

existing PM10 increments. Others 

believe that PM2.5 increments finalized 

under section 166(f) must fully replace 

the existing PM10 increments, and 

recommended doing so. 

For the reasons discussed previously 

in this preamble, EPA has decided to 

finalize the PM2.5 increments under the 

authority of section 166(a) of the Act. 

With respect to the potential creation of 

PM2.5 increments under section 166(f) 

(as discussed in the 2007 NPRM at 72 

FR 54120–54121), we have not reached 

any final conclusion as to whether that 

approach is authorized by the statute, 

but believe that such an approach raises 

significant legal issues. Because the 

Agency is not relying on section 166(f) 

in this rulemaking, we do not address 

these issues in this preamble, though 

some additional discussion is included 

in the Response to Comments document 

for this rule. 

One industry association that 

supported the Option 1 approach based 

on section 166(a) authority also 

acknowledged that EPA is authorized to 

use the Option 2 approach based on 

section 166(f) authority. An industry 

commenter indicated that 2007 NPRM’s 

arguments regarding the alternative 

legal authorities under section 166(a) 

and (f) were not compelling; the 

commenter recommended setting the 

PM2.5 increments at the levels proposed 

as Option 2B because they would have 

the lowest economic impact. 

As noted previously, we have decided 

to finalize Option 1 based on section 

166(a) authority because we believe that 

provision provides the clearest statutory 

authority for purposes of developing 

increments based on PM2.5. We would 

point out, however, that any conclusion 

as to which option would yield 

increments that ‘‘have the lowest 

economic impact’’ must include a 

consideration of not only the levels of 

the increments but also the associated 

baseline dates that define when 

emissions changes must be considered 

to affect the amount of increment 

consumed. Under Options 2 and 3, the 

PM2.5 increments would be regarded as 

replacement increments for the PM10

increments and, as such, would include 

amounts of increment (based upon the 

PM2.5 component) already consumed 

under the existing PM10 increment 

system. Thus, portions of the substitute 

PM2.5 increments could have already 

been consumed by previous PSD 

sources that emit PM. If, in fact, a 

portion of the PM2.5 increments had 

already been consumed by the prior 

PM10 increment consumption process, 

than there would be a basis to conclude 

that less additional economic growth 

would be allowed under a set of 

replacement PM2.5 increments as 

compared to PM2.5 increments based on 

separate, independent baseline dates. 

One industry commenter suggested 

that EPA develop geographic areaspecific increments (and SILs and 

SMCs) that take local conditions into 

account. The commenter pointed out 

that PM2.5 levels in PSD areas proximate 

to international borders may be elevated 

by sources outside the legal and 

practical control of the United States 

and State authorities. The commenter 

also noted that PM2.5 levels may be 

elevated by natural conditions, such as 

drought, fires, geologic formations 

(sandy or fine-grained surface features), 

high winds, etc., leading to excessively 

dusty ambient conditions over which 

the local area has no control. The 

commenter indicated that local area 

baselines must reflect these PM 

emissions, though they are not reflected 

in the local area’s emissions inventory. 

The commenter urged EPA not to 

penalize such PSD areas by imposing 

uniform national PSD increments (or 

SILs or SMCs) where the conditions of 

concern are not capable of control. 

As previously discussed, this final 

rule establishes an area classification 

system with prescribed, uniform PM2.5

increments for each class. We do not 

believe that it is necessary to develop 

different increments (or SILs or SMC) 

for different areas of the country. 

Emissions from natural conditions such 

as those described by the commenter 

would not consume increment due to 

their natural and temporary nature. In 

addition, if a State wishes to disregard 

new emissions from sources outside the 

United States, the State’s PSD program 

may provide that such emissions do not 

consume increment (see 40 CFR 

51.166(f)(1)(iv)). 

VI. Final Action on PM2.5 SILs 

A. EPA’s Determination on SILs for 

PM2.5

It is EPA’s longstanding policy to 

allow the use of the SILs as de minimis 

thresholds under the NSR programs at 

40 CFR 51.165(b) and part 51, Appendix 

S, to determine whether the predicted 

ambient impact resulting from the 

emissions increase at a proposed major 

new stationary source or modification is 

considered to cause or contribute to a 

violation of the NAAQS. We have also 

allowed the SILs under the PSD 

program to determine: (1) When a 

proposed source’s ambient impacts 

warrant a comprehensive (cumulative) 

source impact analysis; (2) the size of 

the impact area within which the air 

quality analysis is completed, and (3) 

whether the emissions increase from a 

proposed new major stationary source 

or major modification is considered to 

cause or contribute to a violation of any 

NAAQS. 

We proposed three separate options 

for setting SILs for PM2.5. The first 

option relied upon the same approach 

we proposed for PM10 in the 1996 NSR 

Reform proposal. This set included 

Class I SILs set at 4 percent of the Class 

I PM2.5 increments. For class II and III 

areas, we proposed to codify the SIL 

values that already existed for PM10, i.e., 

1.0 μg/m3 (annual) and 5.0 μg/m3 (24- 

hour). Options 2 and 3 relied on scaling 

the PM10 SILs, as codified in 40 CFR 

51.165(b), by a particular ratio. 

Specifically, for Option 2, the multiplier 

was the emissions ratio of PM2.5 to PM10

for point sources in the 1999 NEI; for 

Option 3 the multiplier was the ratio of 

the PM2.5 NAAQS to the PM10 NAAQS. 

The resulting SILs were proposed as 

follows: 

Option 

Proposed SILs (μg/m3) 

Class I Class II Class III 

Annual 24-hr Annual 24-hr Annual 24-hr 

1 ....................................................................................................................................... 0.04 0.08 1.0 5.0 1.0 5.0 

2 ....................................................................................................................................... 0.16 0.24 0.8 4.0 0.8 4.0 

3 ....................................................................................................................................... 0.06 0.07 0.3 1.2 0.3 1.2 


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21We note that, under the 2007 NPRM, we 

proposed that the SILs for PM2.5 would not be 

treated as a minimum program element for State 

PSD programs; however, the proposed regulatory 

language at 40 CFR 51.166(k)(2) incorrectly stated 

the ‘‘the plan shall provide that,’’ which would 

indicate that the use of the SILs for PM2.5 was 

required in the State plan. This final rule corrects 

this error. 

We have decided to finalize the PM2.5

SILs proposed under Option 3. As 

explained earlier, these values will be 

used in the Federal PSD preconstruction 

review process consistent with our 

proposal. See 72 FR 54138–41 and 

54143. 

States are not required to adopt SILs 

in their NSR or PSD programs; the 

analyses for PM2.5 required by each 

applicable regulation can be carried out 

without using a SIL.21 Therefore, we do 

not intend for any specific deadlines to 

apply under the regulations at 40 CFR 

51.165(b), 51.166, or part 51, Appendix 

S for states to submit SILs for PM2.5, 

should they choose to do so, as part of 

their revisions to incorporate the final 

rules for PM2.5 into SIPs. Nonetheless, 

we believe that the availability of SILs 

as a screening tool greatly improves PSD 

program implementation by 

streamlining the permit process and 

reducing labor hours necessary to 

submit and review a complete permit 

application where the projected impact 

of the proposed source is de minimis in 

the relevant area. For these reasons, we 

are including the PM2.5 SILs in the 

Federal PSD regulations at 40 CFR 52.21 

to screen proposed projects concerning 

the need for a cumulative source impact 

analysis for PM2.5. 

B. Response to Comments Concerning 

the SILs 

The primary purpose of the SILs is to 

identify a level of ambient impact that 

is sufficiently low relative to the 

NAAQS or increments that such impact 

can be considered trivial or de minimis. 

Hence, the EPA considers a source 

whose individual impact falls below a 

SIL to have a de minimis impact on air 

quality concentrations that already 

exist. Accordingly, a source that 

demonstrates that the projected ambient 

impact of its proposed emissions 

increase does not exceed the SIL for that 

pollutant at a location where a NAAQS 

or increment violation occurs is not 

considered to cause or contribute to that 

violation. In the same way, a source 

with a proposed emissions increase of a 

particular pollutant that will have a 

significant impact at some locations is 

not required to model at distances 

beyond the point where the impact of its 

proposed emissions is below the SILs 

for that pollutant. When a proposed 

source’s impact by itself is not 

considered to be ‘‘significant,’’ EPA has 

long maintained that any further effort 

on the part of the applicant to complete 

a cumulative source impact analysis 

involving other source impacts would 

only yield information of trivial or no 

value with respect to the required 

evaluation of the proposed source or 

modification. 

While some commenters opposed all 

of the proposed options for PM2.5 SILs, 

most commenters generally supported 

the use of a SIL as a screening tool for 

PM2.5 air quality analyses. Commenters 

who supported one of the proposed 

options for the SILs were divided as to 

their support of a particular approach 

for selecting the SIL value, with each 

option receiving some support. 

Commenters also tended to agree that 

the SILs should not be used for 

determining significant impacts on 

AQRVs in Class I areas. 

Those commenters supporting the 

concept of the SILs, yet opposing all 

proposed options, believed that all 

options yielded SILs that were too low. 

Another commenter, an environmental 

group, presented extensive legal and 

policy arguments against the SILs 

concept in general. Some of the 

significant comments and our responses 

to them are addressed herein, while 

others are covered in the Response to 

Comments document which we have 

placed in the docket for this rulemaking. 

1. Legal Basis for SILs 

One commenter opposed all three 

proposed options on both legal and 

policy grounds claiming that EPA has 

no legal authority to promulgate SILs 

and that the de minimis doctrine 

endorsed by the court does not apply to 

increment analyses, where Congress has 

expressly directed that the letter of the 

law applies in all circumstances, as it 

has in this case. (The commenter’s 

policy concerns about SILs are 

discussed later in this section of this 

preamble.) The commenter stated that 

‘‘Congress codified increments in 

section 163 of the Act, directing that 

SIPs contain measures assuring that the 

increments shall not be exceeded.’’ 

According to the commenter, ‘‘The Act 

plainly provides that no major source 

may be constructed unless it meets this 

requirement, and may not contribute to 

an exceedance ‘for any pollutant in any 

area.’ ’’ The commenter further stated 

that ‘‘the de minimis doctrine is 

inapplicable because it applies only 

where the regulations will yield a gain 

that is demonstrably trivial or zero.’’ 

We disagree with this commenter’s 

claim that there is no legal basis for 

SILs. As stated in the 2007 NPRM, the 

concept of a SIL is grounded on the de 

minimis principles described by the 

court in Alabama Power at 323, 360. In 

this case reviewing EPA’s 1978 PSD 

regulations, the court recognized that 

‘‘there is likely a basis for an implication 

of de minimis authority to provide 

exemption when the burdens of 

regulation yield a gain of trivial or no 

value.’’ Alabama Power at 360. See the 

2007 NPRM for more on how we have 

applied the de minimis principle in the 

past. See also, Sur Contra La 

Contaminacion v. EPA, 202 F.3d 443, 

448–49 (1st Cir. 2000) (upholding EPA’s 

use of SILs to allow permit applicant to 

avoid full impact analysis.) 

2. Levels of the SILs 

Several commenters opposed all three 

proposed options on the grounds that all 

yielded levels of SILs that are too low. 

One of these commenters argued that 

the proposed SILs ‘‘imply a level of 

monitoring and modeling sophistication 

that is currently absent in our regulatory 

scheme.’’ This commenter 

recommended that EPA ‘‘rethink the 

level of the proposed SILs and select 

concentrations less likely to be within 

the level of error inherent in current 

monitoring and modeling methods.’’ 

We disagree with these commenters’ 

concerns about all the proposed SILs 

being too low. While we did not select 

the Option 1 levels, the Class II and III 

SILs for PM2.5 under that option were 

the same ambient concentration levels 

that are used for the SILs for the other 

criteria pollutants under 40 CFR 

51.165(b), and those existing SILs values 

are associated with NAAQS that are 

considerably higher than the NAAQS 

for PM2.5. Clearly, it would have been 

inappropriate to select Class II and III 

SILs for PM2.5 that represent relatively 

higher values than the existing SIL 

values for other pollutants in light of the 

more stringent NAAQS levels that exist 

for PM2.5. We also disagree that the SILs 

should be consistent with current 

monitoring capabilities for PM2.5. The 

SILs are a screening tool used in 

comparison with modeled predictions— 

not monitored concentrations—of PM2.5. 

Monitoring accuracy is not a relevant 

concern in predicting with air quality 

dispersion models the concentrations of 

a pollutant that a source will cause if its 

construction and operation are allowed 

to occur. 

Two commenters expressed concern 

about national de minimis values. One 

stated that ‘‘the idea that a single 

national number can define ‘trivial’ is 

flawed, given that even very small 

impact can be of great significance in an 

area that is close to an increment or 

NAAQS.’’ The other commenter 


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22See ‘‘Information Collection Request (ICR) for 

the Prevention of Significant Deterioration for 

PM2.5-Increments, Significant Impact Levels and 

Significant Monitoring Concentration,’’ Docket No. 

EPA–HQ–OAR–2007–0628. 

recommended that EPA ‘‘develop 

geographic area-specific * * * levels 

that take local conditions into account.’’ 

This commenter reasoned that some 

PSD areas ‘‘should not be ‘penalized’ by 

a single, national PSD increment, 

significant impact levels and significant 

monitoring level, where the conditions 

of concern are not capable of control.’’ 

With regard to the first of these 

commenters, our longstanding policy 

has been that when a source has a de 

minimis impact on an existing air 

quality problem, that source should not 

necessarily be required to bear the 

burden of addressing its small 

contribution to a problem caused 

primarily by other sources. However, 

notwithstanding the existence of a SIL, 

permitting authorities should determine 

when it may be appropriate to conclude 

that even a de minimis impact will 

‘‘cause or contribute’’ to an air quality 

problem and to seek remedial action 

from the proposed new source or 

modification. 

We do not agree with the second of 

these comments concerning the 

development of regional SILs based on 

a concern that some amounts of PM2.5 in 

a particular area are ‘‘not capable of 

control.’’ The PM2.5 SILs define a 

threshold level for determining whether 

a predicted ambient impact by a 

proposed major stationary source or 

major modification of PM2.5 needs to 

undergo a more thorough analysis of the 

PM2.5 NAAQS or increments. This value 

is not directly affected by the total 

amounts of PM2.5 that may exist in an 

area or by what causes the existing 

PM2.5 concentrations, rather by the 

impact of a single source relative to the 

levels of the NAAQS and increments 

that must be protected. Therefore, we do 

not see why the SILs should be 

influenced by the geographic area of 

concern, or how different levels of SILs 

for the same pollutant and averaging 

period would be necessary. 

With regard to the commenters that 

supported at least one of the proposed 

SILs options, they generally did not 

prefer the entire suite of SILs (Class I, 

II, and III SILs) from a single option, but 

instead supported parts of different 

options, primarily divided by drawing a 

distinction between the Class I SILs and 

the SILs for Class II and III areas. 

Consistent with the way that 

commenters addressed the Class I, II, 

and III SILs, we will address the 

comments separately herein as well. 

a. Class I SILs 

Support and opposition for the 

proposed PM2.5 SILs for Class I areas 

was fairly evenly divided. The PM2.5

SILs for Class I areas proposed under 

Option 2 received the support of some 

commenters, but also received an equal 

amount of opposition. Option 1, which 

yielded the lowest (most restrictive) 

values for the Class I area SILs for PM2.5

(annual and 24-hour averages), was 

supported by some commenters, 

including a Federal agency that serves 

as a FLM for Federal Class I areas under 

the PSD program, but was equally 

opposed. Finally, comments supporting 

the Class I SILs proposed under Option 

3 (from which we derived the values 

included in the final rules) were 

matched by comments that opposed the 

Class I SILs under Option 3. 

One commenter opposing the Option 

3 SILs for Class I areas said that the 

values ‘‘appear to be unrealistically low 

and, if selected, would point to the need 

for EPA to conduct an economic impact 

analysis.’’ We disagree that adopting the 

Option 3 SILs for Class I areas (and 

Class II and III areas) will result in 

economic impacts significant enough to 

warrant an economic impact analysis. 

Under the Paperwork Reduction Act, 

EPA is required to analyze, and receive 

approval from the Office of Management 

and Budget (OMB) for, the 

recordkeeping and reporting burden 

imposed by its regulations (referred to 

as the ‘‘Information Collection Request’’ 

or ‘‘ICR’’ for the regulation). For the PSD 

program, this includes the burden 

associated with the entire permitting 

process, including any required 

modeling analyses. In our analysis for 

this rulemaking, we have concluded 

that the number of PSD permits issued 

annually will be unchanged (at an 

estimated 274 per year), while the total 

burden across all PSD permit applicants 

of adding PM2.5 analyses will increase 

by a total of approximately 29,000 hours 

per year at a cost of approximately $2.8 

million per year. This total annual 

impact on industry is a small fraction of 

the threshold ($100 million per year) 

that is considered ‘‘significant’’ under 

Executive Order 12866 (Regulatory 

Planning and Review) and the 

Unfunded Mandates Reform Act. See 

sections X.B and X.D of this preamble 

for more on the Paperwork Reduction 

Act and the Unfunded Mandates Reform 

Act, respectively. Our analysis of the 

recordkeeping and reporting burden of 

this rulemaking can be found in the 

docket for this ICR.22

Another commenter stated that the 

use of a NAAQS-based ratio under 

Option 3 for the proposed SILs does not 

‘‘translate back to the emissions point 

level when comparing PM10 and PM2.5.’’ 

This commenter continued, ‘‘this is an 

invalid method of proceeding because 

EPA has not shown that there is a 

correlation between the NAAQS and 

direct PM2.5 since there is no accounting 

for precursors and EPA does not have a 

quantifiable sense of the portion of 

PM2.5 that is condensable for various 

industries.’’ 

We disagree with the commenter’s 

concern that the use of NAAQS-based 

ratios is an invalid method for 

developing the PM2.5 SILs. The purpose 

of using the NAAQS ratio with the PM10

SILs to develop PM2.5 SILs is to 

establish values that have a comparable 

relationship between ambient 

concentrations of PM10 and PM2.5 and 

their respective NAAQS levels. Whether 

a particular ambient concentration of 

PM2.5 results from direct PM2.5

emissions or from precursor emissions 

is not relevant to this particular 

approach. The PM2.5 SILs in this final 

rule are intended to be compared to the 

ambient concentrations of PM2.5 that are 

predicted by modeling the emissions of 

a proposed new project. Ambient 

concentrations of PM2.5 can be the result 

of direct PM2.5 emissions, which may 

include condensable particulate matter, 

as well as precursor emissions, e.g., SO2

and NOX. 

We note that the 2007 NPRM 

included proposed regulatory language 

providing that demonstrations of 

whether the air quality impact of a 

major new source or modification 

would be less than the PM2.5 SILs be 

based on direct PM2.5 emissions from 

the proposed project. The intent of this 

was to recognize the technical 

limitations associated with modeling 

precursor emissions to predict ambient 

PM2.5 impacts. However, in this final 

rule we have removed that limitation by 

removing the reference to ‘‘direct’’ PM2.5

emissions. 

One commenter, who did not support 

any of the proposed SILs options, was 

especially critical of the Class I SILs for 

PM2.5 under Option 1, stating that 

multiplying the proposed PM2.5

increment by 4 percent is without legal 

or practical merit. The commenter 

stated that just because ‘‘4 percent may 

have been a reasonable multiplier to use 

in establishing a significant emission 

rate threshold does not mean that the 

multiplier should be used for a 

completely different regulatory 

purpose.’’ The commenter added that if 

the PM2.5 SILs for Class I areas under 

Option 1 were codified, emissions from 

even the most well-controlled coal-fired 

electric generating station located as far 

away as 300 km from a Class I area 

could well exceed the threshold. 


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In contrast, the Federal agency 

commenter supporting the PM2.5 SILs 

for Class I areas under Option 1 

explained that they analyzed the 

effectiveness of the three sets of 

proposed SILs by modeling four 

different coal-fired power plant 

scenarios using an EPA-approved longrange transport model. The modeled 

plants included a large 1,500 megawatt 

(MW) facility, a moderate-sized 500 MW 

facility, and two medium 800 MW 

facilities. Based on this modeling 

analysis, the commenter concluded that 

the proposed levels of the Class I 24- 

hour SILs based on Option 1 and Option 

3 are ‘‘more appropriately protective of 

the proposed Class I PM2.5 increment 

and impacts to visibility than the level 

obtained under Option 2.’’ This 

commenter supported the consistency of 

using 4 percent of the Class I increments 

that was used by EPA in proposing 

Class I SILs for SO2, NOX, and PM10 in 

1996. 

We chose the Class I SILs under 

Option 3 because we believe that this 

option yields the most appropriate 

combination of SILs for all area 

classifications. Whether a particular 

source will have a significant impact on 

an area is determined to some extent by 

the amount of its emissions, but also by 

other factors such as the height of 

release, pollutant transport distance, 

terrain features, and meteorological 

factors. Thus, we did not select SILs 

values to address a certain size source 

or the degree of control of that source, 

but the ambient impact of that source 

relative to the NAAQS and increments 

that will result from the source’s 

emissions. While the annual Class I SIL 

under Option 3 represents a level that 

is somewhat greater than 4 percent of 

the PM2.5 annual increment for Class I 

areas, it is sufficiently close (as derived 

from a ratio of the PM2.5 NAAQS to the 

PM10 NAAQS) so as to provide a 

reasonable threshold for defining de 

minimis for purposes of conducting a 

Class I increment analysis. We had 

proposed the use of 4 percent of the 

existing Class I increments to develop 

SILs for pollutants in the 1996 NSR 

Reform proposal; however, that 

particular component of the proposal 

was never finalized. See 61 FR 38250 

beginning at 38291. We will further 

discuss our rationale for selecting the 

SILs under Option 3 in the discussion 

which follows for the Class II and III 

SILs. 

b. Class II and III SILs 

While many commenters tended to 

favor Option 2 with regard to the 

proposed Class I increments, they 

tended clearly to support Option 1 for 

defining Class II and III SILs for PM2.5. 

These particular SILs for PM2.5 were 

proposed so as to be equal to the 

existing Class II and III SILs for the 

existing pollutants. In all, six 

commenters supported Option 1. One of 

these commenters stated that Option 1 

SILs for Class II and III areas are 

‘‘sufficiently stringent and fully 

consistent with the de minimis 

justification for SILs.’’ The commenter 

added that ‘‘when conducting an air 

quality impact analysis * * * most 

applicants assume all coarse PM10 to be 

PM2.5.’’ The commenter claimed that 

this assumption is conservative and 

‘‘overestimates the amount of fine 

particles being emitted and renders the 

effective SIL thresholds for PM2.5 lower 

than those written into the regulations.’’ 

We strongly disagree that the SILs 

proposed under Option 1 as applied to 

PM2.5 are sufficiently stringent. The 

application of such values as SILs for 

PM2.5 would result in ambient 

concentrations of PM2.5 that consume a 

much larger portion of both the PM2.5

NAAQS and increments than either of 

the other two options proposed for 

PM2.5 in light of the correspondingly 

more stringent levels of the PM2.5

NAAQS and increments than those for 

the other pollutants. We believe that of 

the 3 options proposed, the PM2.5 SILs 

based on Option 3 represent values that 

are more closely aligned percentagewise with the SILs that have been or are 

being used for other forms of PM when 

compared to their respective NAAQS 

and increments. 

We also disagree with the 

commenter’s suggestion that the 

development of the SILs for PM2.5, or 

any other pollutant, should in any way 

be influenced by the possibility that 

some sources may use conservative 

techniques for estimating a source’s 

emissions rate. Such conservative 

techniques may be needed to the extent 

that technical issues associated with the 

determination of PM2.5 emissions are 

identified, and can certainly be used at 

any time as a simplified methodology 

for estimating PM2.5 emissions. But 

when such an overly conservative 

approach fails to yield de minimis 

results, the source may find it necessary 

to rely upon more accurate techniques 

for determining the amount of PM2.5 that 

the source will emit. 

Finally, one commenter, objecting to 

all of the proposed SILs, stated that EPA 

must assure that SILs are truly de 

minimis and must also include 

limitations on the use of SILs as 

necessary to prevent air quality from 

significantly deteriorating. We 

acknowledge that we did not conduct 

any new modeling or other types of 

analyses of the proposed SILs in order 

to explicitly show that the final PM2.5

SILs values in this final rule are de 

minimis. Instead, we have relied on past 

actions regarding the setting of de 

minimis levels to illustrate that the 

PM2.5 values selected via Option 3 

represent values that are as stringent as 

the previous levels that have been 

established to define de minimis for 

PM10 and TSP. See 45 FR 52706–708 

(using modeling and representative 

data). 

Using the 24-hour and annual 

NAAQS ratios of PM2.5 to PM10, and 

multiplying them by the corresponding 

existing PM10 SILs, we conclude that the 

PM2.5 SILs define de minimis for the 

PM2.5 NAAQS in the same way as the 

PM10 SILs do for PM10 NAAQS. Using 

the increments as a basis for comparison 

provides further support for our 

conclusion. The annual and 24-hour 

PM2.5 SILs represent about 7.5 and 13 

percent of the annual and 24-hour PM2.5

increments, respectively. By 

comparison, the annual and 24-hour 

PM10 SILs represent about 5 and 17 

percent of the annual and 24-hour PM10

increments, respectively. We believe the 

PM2.5 SILs fall into a comparable 

relative range with the PM10 SILs and 

can be considered de minimis. 

In EPA’s 1980 final rule for PSD, EPA 

adopted SERs for the pollutants then 

subject to regulation under the PSD 

requirements. The SER adopted for PM 

(then measured as TSP) was 25 tpy, 

which represented an emissions rate for 

which EPA modeled impacts that 

represented about 4 percent of the TSP 

24-hour NAAQS and about 28 percent 

of the 24-hour TSP increment. Thus, 

EPA considered it acceptable under the 

de minimis assessment for PM that a 

source of particulate matter capable of 

consuming around 28 percent of the 

applicable 24-hour TSP increment could 

be exempted from the requirements to 

complete a comprehensive source 

impact analysis for the PM NAAQS and 

increments. 45 FR 52708. 

In looking at the amount of increment 

that could be consumed by a source that 

is ultimately exempted from having to 

complete a comprehensive modeling 

analysis, it should be pointed out that 

the maximum modeled concentration 

typically occurs in a relatively limited 

area, as compared to the entire modeling 

domain. In particular, for the short-term 

averaging periods, such as the 24-hour 

averaging period, modeled 

concentrations across the modeled area 

generally show that ground level 

impacts are reduced significantly from 

the peak value as the pollutant travels 

a relatively short distance from the 

source, so that the peak modeled 


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concentrations represent the source’s 

impact at only a relatively few receptors 

within the modeled area. In addition, it 

is important to note that the temporal 

and spatial conditions which lead to a 

maximum impact by one source are 

seldom the same for other sources, such 

that maximum impacts of individual 

sources do not typically occur at the 

same location or at the same time. 

Thus, in an area where several 

sources can demonstrate that their 

modeled impacts are de minimis, it 

generally should not be assumed that 

their individual maximum (albeit de 

minimis) impacts on the increment are 

additive. For example, four sources with 

de minimis PM2.5 impacts, each 

consuming 12 percent of the 24-hour 

PM2.5 increment, would not necessarily 

consume 48% of the 24-hour increment. 

Increment consumption is determined 

by the cumulative impact of source 

emissions on each individual receptor 

or modeling point in the area of impact 

within the baseline area defined for the 

affected PSD sources. 

The preamble for the 1980 final rule 

for PSD included a description of a 

modeling analysis that EPA conducted 

to illustrate that a number of major 

sources each making a de minimis 

emissions increase for SO2 could locate 

in an area (in that case, the Dayton area) 

and not cause a violation of either the 

applicable SO2 increment or NAAQS. In 

that particular case, the modeling 

indicated that the maximum aggregate 

increment consumption for 37 sources 

emitting 40 tpy of SO2 (the de minimis 

emissions rate for SO2) would have a 

cumulative impact at any location of 

less than 1.5 μg/m3 on a 24-hour basis— 

well below the NAAQS and increments 

for SO2. 45 FR 52708. 

With regard to the commenter’s 

recommendation that we place 

limitations on the use of SILs, we earlier 

provided an example of when it might 

be appropriate to require a modified 

source to mitigate its contribution to a 

violation of a NAAQS or increment even 

when the predicted ambient impact of 

the proposed emissions increase would 

result in what is normally considered to 

be de minimis. In addition, we have 

historically cautioned states that the use 

of a SIL may not be appropriate when 

a substantial portion of any NAAQS or 

increment is known to be consumed. 

We have indicated elsewhere in this 

preamble that states are not required to 

adopt the SILs for PM2.5 in this final 

rule. At their discretion they may 

choose not to rely on SILs to screen 

applicants or they may establish more 

stringent values. 

Finally, it should be noted that while 

a source having only de minimis 

impacts may not be required to 

complete a comprehensive source 

impact analysis, the emissions from 

such sources are still considered to 

consume increment and would be 

counted as part of the next increment 

analysis required to be completed by a 

PSD applicant in that same area, or by 

the State under a periodic increment 

review. 

3. Relationship Between SILs and 

AQRVs 

While commenters generally 

supported EPA’s position that the SILs 

should not be used in any way to 

determine effects of emissions increases 

on the AQRVs in a Class I area, two 

commenters urged that the de minimis 

concentration be used for analyzing 

Class I area impacts under certain 

circumstances. That is, they believed 

that the SILs should be used to 

determine the need for a Class I area air 

quality analysis when an FLM has not 

identified a specific AQRV related to the 

pollutant under evaluation or obtained 

ambient monitoring data to confirm that 

predicted concentrations from air 

dispersion models are representative of 

actual AQRV impacts in the Class I area. 

The commenters claimed that without 

this flexibility, applicants would be 

required to conduct complex and 

extensive Class I air dispersion 

modeling without any clear objective, 

and regulatory agencies would have to 

review the modeling with limited 

information to determine if the 

emissions could cause an ‘‘adverse’’ 

impact or if potentially costly controls 

should be required. 

These commenters appear to be 

suggesting that an FLM may needlessly 

call for an analysis of a particular Class 

I area, involving ‘‘complex and extensive 

Class I area dispersion modeling’’ 

despite the fact that no AQRV has been 

identified for that Class I area. We agree 

that a Class I analysis in the absence of 

any known AQRVs would be 

unnecessary because any demonstration 

of an adverse impact must be made with 

respect to a pollutant adversely affecting 

an AQRV. We believe, however, that 

such analyses would be avoided under 

the procedures set forth in section 

165(d)(2)(C) of the Act which require 

that a notice be filed alleging that a 

proposed source may cause or 

contribute to adverse effects, and 

identifying the adverse impact. Insofar 

as the FLM must also demonstrate ‘‘to 

the satisfaction of the State that 

emissions from such facility will have 

an adverse impact on the air quality 

related values,’’ it would be difficult to 

require the source to undertake any kind 

of detailed analysis in the absence of an 

AQRV on which such adverse impacts 

must be demonstrated. Thus, we have 

concluded that it is not necessary to use 

the SILs as a safeguard against 

unnecessary Class I area analyses. 

Instead, we believe that the need for a 

Class I analysis, other than the required 

analysis of the NAAQS and Class I 

increments (for both of which the SILs 

are intended to be used), should be 

based on the potential for adverse 

effects on an AQRV that the FLM has 

identified and believes could be affected 

by a pollutant that would be emitted by 

the proposed project. 

4. Form of the SILs 

One commenter stated that ‘‘the 

Proposal does not indicate how the 

proposed PM2.5 SILs are to be 

interpreted.’’ This commenter believed 

that ‘‘the form of the SILs should be 

consistent with the form of the PM2.5

NAAQS’’ adding that ‘‘the current PM2.5

NAAQS requires that compliance with 

the 24-hour and annual standards be 

determined using 3-year averaging.’’ 

Specifically, ‘‘The annual standard is 

calculated based upon the 3-year 

average of annual mean PM2.5

concentrations, and the 24-hour 

standard is based on the 3-year average 

of the 98th percentile (or highest-8th 

high value) of 24-hour concentrations.’’ 

In a March 23, 2010 EPA 

memorandum titled ‘‘Modeling 

Procedures for Demonstrating 

Compliance with PM2.5 NAAQS,’’ we 

provided guidance for using the SILs in 

conjunction with the 24-hour and 

annual PM2.5 NAAQS, which takes into 

account the statistical form of the 

NAAQS. Following promulgation of the 

PM2.5 increments in this final rule, we 

intend to provide guidance for 

interpreting the SILs for their use with 

the 24-hour and annual PM2.5

increments as well. 

5. SILs for Other Pollutants 

In proposing Option 1, we noted that 

many who commented on the 1996 NSR 

Reform proposal supported this 

approach and believed that the 

proposed PM10 SIL values would serve 

as appropriate de minimis values. In 

fact, we are aware that many states have 

been using these proposed SILs for PM10

as screening tools since 1996 or earlier. 

Regarding the proposed Class I SILs 

under Option 1, we expressed our belief 

that where a proposed source consumes 

less than 4 percent of the Class I 

increment, the source’s impact is 

sufficiently low so as not to warrant 

requiring the source to carry out a 

detailed analysis of the combined effects 

of the proposed source and all other 

increment-consuming emissions in the 


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23 In 1985, the requirements now contained in 40 

CFR 51.165(b) were contained in 40 CFR 51.18(k), 

which was later part of a major restructuring of the 

part 51 SIP requirements. 

24 In the case of a NAAQS compliance analysis, 

all sources in the area are considered to contribute 

to the air quality levels; for increments, however, 

‘‘all’’ refers only to those sources whose emissions, 

in whole or in part, consume PSD increment for a 

particular pollutant. 

25The provision for the monitoring exemption 

was originally promulgated at 40 CFR 51.24(i)(8) 

and 52.21(i)(8); it should be noted, however, that 

this provision is now found at 40 CFR 51.166(i)(5) 

and 52.21(i)(5). 

area. 72 FR 54140. We previously used 

a similar rationale to establish the SERs 

for PSD applicability purposes, 

concluding in part that emissions rates 

that resulted in ambient impacts less 

than 4 percent of the 24-hour standards 

for PM and SO2 were sufficiently small 

so as to be considered de minimis. 45 

FR 52707–8. 

The original SIL values of 1.0 and 5.0 

μg/m3 for TSP and PM10 were 

interpreted by EPA as representing the 

minimum amount of ambient impact 

that is significant. This formed the basis 

for the proposed Option 1 PM2.5 SIL 

values of 1.0 and 5.0 μg/m3 for the 

annual and 24-hour averaging periods 

for Class II and III areas. 

The SILs currently appear in EPA’s 

regulations at 40 CFR 51.165(b). That 

particular NSR regulation provides that 

states must include a preconstruction 

review permit program for any new 

major stationary source or major 

modification that proposes to locate in 

an attainment or unclassifiable area and 

would cause or contribute to a violation 

of the NAAQS. These values, added to 

40 CFR 51.165(b) on July 1, 1987, have 

previously been referred to as 

‘‘significant ambient impact 

concentrations’’ and are used to enable 

a source to determine whether its 

emissions would cause or contribute to 

a NAAQS violation at ‘‘any locality that 

does not or would not meet the 

applicable national standard.’’ 52 FR 

24672, April 2, 1985, at 24688. 

In 1985, when EPA proposed to add 

‘‘significant ambient impact levels’’ for 

PM10, we also indicated that for PSD 

purposes the requirements under 

section 51.165(b) 23 ‘‘would be applied 

to all applicable PSD requirements.’’ The 

EPA has since applied these values in 

other analogous circumstances under 

the PSD program. Based on EPA 

interpretations and guidance, SILs have 

also been widely used in the PSD 

program as a screening tool for 

determining when a new major source 

or major modification that wishes to 

locate in an attainment or unclassifiable 

area must conduct a more extensive air 

quality analysis to demonstrate that it 

will not cause or contribute to a 

violation of the NAAQS or PSD 

increment in the attainment or 

unclassifiable area. The SILs are also 

used to define the extent of the 

Significant Impact Area where, using air 

dispersion models and ambient 

monitoring data, a cumulative source 

impact analysis accounting for 

emissions changes from affected sources 

is performed.24 See the 2007 NPRM for 

additional information on the history of 

EPA’s guidance related to SILs (72 FR 

54138–39). 

In the 1996 NSR Reform proposal, we 

proposed to add the SILs for PM10 and 

other pollutants already contained in 40 

CFR 51.165(b)(2) directly into the PSD 

regulations at 40 CFR 51.166 and 52.21. 

Because the SILs in 40 CFR 51.165(b) 

did not include thresholds for Class I 

areas, we proposed to set Class I SILs at 

the level of 4 percent of the respective 

Class I increments. Thus, for PM10, the 

proposed Class I SILs were 0.2 μg/m3

(annual) and 0.3 μg/m3 (24-hour), and 

the proposed Class II and III SILs were 

1.0 μg/m3 (annual) and 5.0 μg/m3 (24- 

hour). The EPA has not yet taken final 

action on the 1996 proposal on SILs for 

pollutants other than PM2.5; therefore, 

we rely upon our longstanding policy to 

use those values, as codified in 40 CFR 

51.165(b)(2), for PSD permitting. 

VII. Final Action on the PM2.5 SMC 

A. EPA’s Determination on the PM2.5

SMC 

As with the increments and SILs for 

PM2.5, we proposed three different 

options for establishing an SMC for 

PM2.5. The first option, referred to as the 

‘‘lowest detectable concentration’’ 

approach, relied on the method we used 

in 1980 to develop the SMCs for the 

pollutants then subject to PSD. This 

particular method focused on 

development of the SMC value based on 

the current capability of providing a 

meaningful measure of the pollutants. 

See relevant discussion later in this 

section and at 45 FR 52710. Options 2 

and 3, called the ‘‘PM2.5 to PM10

emissions ratio’’ and the ‘‘PM2.5 to PM10

NAAQS ratio,’’ respectively, used the 

SMC for PM10 as the base for 

multiplying the emissions and NAAQS 

ratios to derive an SMC for PM2.5. See 

72 FR 54141. The three proposed 

options yielded the following numerical 

levels for the SMC: 

• Option 1: 10 μg/m3, (24-hour 

average); 

• Option 2: 8.0 μg/m3 (24-hour 

average); and 

• Option 3: 2.3 μg/m3 (24-hour 

average). 

We are taking final action on the SMC 

for PM2.5 using the ‘‘lowest detectable 

concentration’’ approach (Option 1). 

However, we have determined that the 

SMC value that is calculated under this 

methodology is lower than the proposed 

value of 10 μg/m3 to reflect ‘‘current 

capability’’ with respect to the 

measurement and collection of ambient 

PM2.5 concentrations. The result of such 

revised calculation is that the SMC 

value in this final rule is different from 

(more stringent than) the proposed 

level. The revised value is 4 μg/m3 (24- 

hour average). Our basis for the revised 

calculation and the resulting lower 

value is described in greater detail later 

in this section. 

The EPA and its delegated reviewing 

authorities will use the PM2.5 SMC to 

determine when it may be appropriate 

to exempt a proposed new major 

stationary source or major modification 

from the ambient monitoring data 

requirements under the PSD rules. 

Similarly, states with EPA-approved 

PSD programs that adopt the SMC for 

PM2.5 may use the SMC, once it is part 

of an approved SIP, to determine when 

it may be appropriate to exempt a 

particular major stationary source or 

major modification from the monitoring 

requirements under their State PSD 

programs (see 40 CFR 51.166(i)(5)). 

B. Response to Comments Concerning 

the SMC 

1. Legal Issues 

Under the Act and EPA regulations, 

an applicant for a PSD permit is 

required to gather preconstruction 

monitoring data in certain 

circumstances. Section 165(a)(7) of the 

Act calls for ‘‘such monitoring as may be 

necessary to determine the effect which 

emissions from any such facility may 

have, or is having, on air quality in any 

areas which may be affected by 

emissions from such source.’’ In 

addition, section 165(e) of the Act 

requires an analysis of the air quality in 

areas affected by a proposed major 

facility or major modification and calls 

for gathering 1 year of monitoring data 

unless the reviewing authority 

determines that a complete and 

adequate analysis may be accomplished 

in a shorter period. These requirements 

are codified in EPA’s PSD regulations at 

40 CFR 51.166(m) and 52.21(m). 

In 1980, EPA adopted regulations that 

included pollutant-specific SMCs as a 

screening tool for sources to determine 

whether they should conduct sitespecific preconstruction ambient 

monitoring.25 We explained our 


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position that it was appropriate to 

exempt sources from preconstruction 

monitoring requirements for a pollutant 

if the source could demonstrate that its 

ambient air impact was less than a value 

known as the Significant Monitoring 

Concentration or SMC. At the time the 

SMCs were adopted, EPA described 

them as ‘‘air quality concentration de 

minimis level[s] for each pollutant [that 

were available] for the purpose of 

providing a possible exemption from 

monitoring requirements.’’ 45 FR 52676, 

52707 (August 7, 1980). The EPA 

explained that it believed there was 

‘‘little to be gained from preconstruction 

monitoring’’ where a source could show 

that its projected impact of a pollutant 

within the affected area was below the 

de minimis concentration for that 

pollutant. 45 FR at 52710. 

One commenter opposed our 

proposed establishment of any SMC for 

PM2.5, claiming that SMCs in general are 

contrary to the Act. The commenter 

stated that ‘‘in Section 165(e) Congress 

mandated a full year of continuous air 

quality monitoring for each major 

source subject to the PSD program.’’ 

With this in mind, the commenter 

indicated that there are no exceptions, 

other than the limited statutory 

provisions, discussed above, which 

allow for less than a year’s worth of 

monitoring based on a determination 

that a complete and adequate analysis of 

such purposes may be accomplished in 

a shorter period. The commenter then 

argued that ‘‘the allowance for a ‘shorter 

period’ hardly amounts to authority to 

waive monitoring entirely, which is 

what EPA’s SMC proposal would do.’’ 

As with the SMCs adopted by EPA in 

1980, the SMCs that we proposed for 

PM2.5 are supported by the de minimis 

doctrine set forth in the Alabama Power 

opinion. Like the other pollutants for 

which EPA has promulgated SMCs, EPA 

believes there is little to be gained from 

preconstruction monitoring of PM2.5

concentrations that cannot be accurately 

measured. 

Therefore, in developing the three 

proposed options for an SMC, EPA 

sought to use methods that would 

identify levels representing a de 

minimis or insignificant impact on 

PM2.5 ambient air quality that makes the 

collection of additional monitoring data 

extraneous. 

2. Level of the SMC 

As indicated earlier, the SMC for 

PM2.5 in this final rule is 4 μg/m3, 24- 

hour average. This value may be used by 

permitting authorities to determine 

when they may exempt a proposed 

major stationary source or major 

modification for PM2.5 from the air 

quality monitoring requirements for 

PM2.5 under 40 CFR 51.166. The EPA 

and its delegated State/local programs 

will also use this new value under the 

Federal PSD program at 40 CFR 52.21. 

We proposed three options for 

developing the SMC for PM2.5; each 

option yielded a different concentration 

value. In choosing between the three 

options, EPA proposed to select the 

option that reflected the degree of 

ambient impact on PM2.5 concentrations 

that could be considered truly de 

minimis and used to justify exempting 

a source from the requirement to gather 

1 year of ambient monitoring data for 

PM2.5. Ultimately, we have selected the 

‘‘lowest detectable concentration’’ 

approach (Option 1) that relies directly 

upon ambient monitoring measurement 

sensitivity and precision. That is, if 

either the predicted source impact or 

estimated existing air quality in an area 

is below a concentration that can be 

accurately measured, then it would not 

be reasonable to require a source to 

attempt to collect such ambient data. 

In 1980, EPA determined the SMCs 

based on the then current capability of 

providing a meaningful measure of 

ambient pollutant concentrations. The 

EPA promulgated values that 

represented five times the lowest 

detectable concentration in ambient air 

that could be measured by the 

instruments available for monitoring the 

pollutants. 45 FR 52710. The factor of 

‘‘five’’ took into account the 

measurement errors associated with the 

monitoring of these low pollutant levels 

or small incremental changes in 

concentration. These measurement 

errors were said to arise from various 

sources, such as sample collection, 

analytical measurement, calibration, 

and interferences. See May 20, 1980 

EPA memorandum from Rehme, K. A., 

to Warren Peters, contained in the 

docket for this rulemaking. Accordingly, 

in the 2007 NPRM for PM2.5, we voiced 

our belief that this was a reasonable 

approach, since it was also used for 

PM10 and TSP. 72 FR 54141. 

Eight commenters expressed support 

for the SMC based on Option 1, albeit 

at the higher level as originally 

proposed. In some cases, it is not clear 

whether these commenters supported 

the particular approach (i.e., an SMC 

linked to the lowest detectable level) or 

the fact that the calculated value was 

simply the highest value of the values 

proposed under the three options. 

Clearly, some of the commenters 

indicated their support for the approach 

because it is consistent with the 

approach used for setting the original 

SMCs in 1980. Two commenters 

opposed Option 1 because it resulted in 

an SMC value that was too high. These 

latter commenters noted that the SMC 

derived via Option 1 (10 μg/m3, 24-hour 

average) was greater than the proposed 

24-hour PM2.5 increment for Class II 

areas and argued that such an outcome 

is inappropriate. We believe that this 

important concern is adequately 

addressed by the level of the SMC for 

PM2.5 that is established in this 

rulemaking. 

Several commenters supported the 

levels derived from either Option 2 or 

Option 3, but were concerned that the 

justification for choosing either of these 

values would need to be further 

explained. Some of these commenters 

were specifically concerned about the 

use of a 0.8 PM2.5-to-PM10 emissions 

ratio which, they argued, relied on 

inventory data that did not adequately 

address all sources that would likely 

affect ambient concentrations of PM2.5

in an area. 

We conclude that Option 1 is the 

appropriate option for defining the SMC 

for PM2.5. The ability to accurately 

measure ambient PM2.5 concentrations 

is not related to a ratio of PM2.5 to PM10

either directly in terms of emissions or 

as expressed by the respective NAAQS, 

which were used to define the SMC for 

PM2.5 under Options 2 and 3, 

respectively. Our original concern was 

that, while Option 1 linked the SMC 

directly to the concept of a minimum 

detectable concentration (in order to 

identify de minimis monitoring 

circumstances), the value originally 

derived from that approach in the 2007 

NPRM was high in relationship to the 

concentrations of PM2.5 defined by the 

existing NAAQS and increments for 

PM2.5.

In considering the use of Option 1 for 

developing the SMC in the final rules, 

however, we recognized after 

publication of the proposed rule that it 

was necessary to re-examine the 

assumptions that we relied upon in 

1980 to develop the numerical values 

for the original SMCs so that we could 

most accurately reflect current 

monitoring techniques for PM2.5. Our reexamination for this final rule utilized 

the most current information concerning 

the physical capabilities of the PM2.5

Federal Reference Method Samplers, 

and addresses uncertainties introduced 

to the measurement of PM2.5 due to 

variability in the mechanical 

performance of the PM2.5 samplers and 

the micro-gravimetric analytical 

balances that weigh filter samples. 

The minimum detection limit (MDL) 

of 2 μg/m3, originally used in 1980 for 

the SMC for PM and promulgated for 

PM2.5 in 1997 (see 40 CFR part 50, 

Appendix L, section 3.1), has been 


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26This information is contained in a March 12, 

2009 internal EPA memorandum from Dennis 

Crumpler to Raj Rao, titled ‘‘PSD Monitoring De 

Minimis Concentration for PM2.5,’’ which has been 

placed in the docket for this rulemaking. 

reaffirmed by 9 years of field blank data 

collected by EPA through the PM2.5

Performance Evaluation Program. 

However, we found that new data exist 

to ‘‘indicate a conservative estimate of 

the aggregate uncertainty factor is no 

greater that ‘2’ at the concentration 

equal to the MDL of 2 μg/m3.’’ 26

Accordingly, the lowering of the 

uncertainty factor from ‘‘five’’ to ‘‘two’’ 

under Option 1 yields an SMC of 4 μg/ 

m3 PM2.5, 24-hour average, rather than 

the proposed concentration of 10 μg/m3. 

We conclude that the modified level 

of 4 μg/m3 PM2.5, 24-hour average, for 

the SMC under Option 1, based upon a 

more current understanding of 

monitoring precision for PM, especially 

fine PM, addresses commenter support 

for the use of a method that is consistent 

with the way other SMCs were 

developed and most directly reflects 

monitoring capability for the pollutant 

of concern, while at the same time 

responding to the concern of other 

commenters that a value in the lower 

range of proposed SMC values is most 

reasonable considering the levels of the 

NAAQS and increments for PM2.5. 

C. Correction of Cross Reference in PSD 

Ambient Monitoring Requirements 

In the 2007 NPRM, we proposed to 

take final action to correct a cross 

reference contained in paragraph (i) of 

the part 51 and 52 PSD regulations. 

Specifically, at the time of the proposal, 

paragraphs (ii) and (iii) in 40 CFR 

51.166(i)(5), and paragraph (ii) in 40 

CFR 52.21(i)(5), each referred to 

concentrations listed in paragraph 

(i)(8)(i) of both regulations. However, 

there is no paragraph (i)(8)(i) in existing 

40 CFR 51.166, and no concentration 

values are contained in existing section 

(i)(8)(i) of 40 CFR 52.21. The cross 

reference in these provisions was 

intended to reference the SMCs in 

paragraph (i)(5)(i) of the two PSD 

regulations, but EPA failed to make this 

change when the paragraphs were 

renumbered in an earlier rulemaking. 

We did not receive any comments 

concerning this proposed corrective 

action. We made the necessary 

correction as part of the May 16, 2008 

final PM2.5 NSR Implementation Rule 

(see 73 FR 28348 and 28349); therefore 

it is not necessary to take any further 

action in this final rule with regard to 

the proposed correction. 

VIII. Dates Associated With 

Implementation of the Final Rule 

This section describes the key dates 

that we have established for 

implementing the final rule. In the 2007 

NPRM, we indicated that different dates 

appeared to be appropriate for 

implementing the PM2.5 increments, 

each date depending on the legal 

authority that we relied upon to 

promulgate it. We described and took 

comment on some alternative effective 

dates for increments, as well. In 

addition, we discussed and took 

comment on potential implementation 

dates for the SILs and SMC components 

of the proposed rule, which we 

indicated were not subject to the same 

statutory considerations as the 

increments. 

We received a number of comments 

on the different proposed dates. We 

carefully considered these comments in 

selecting the dates described below for 

the final rule. Some of the significant 

comments and our responses to those 

comments are provided below. The 

remaining comments and our responses 

are contained in the Response to 

Comments document included in the 

docket for this rulemaking. 

A. Effective Date of the Final Rule 

In the 2007 NPRM, we took comment 

on the effective date of the final rule by 

presenting the different options 

available for implementing the PM2.5

increments. Under Option 1 for 

developing the increments, we stated 

that section 166(b) of the Act specifies 

that increments promulgated pursuant 

to section 166(a) are to become effective 

1 year following their promulgation. In 

contrast, there is no such 1-year delay 

or any other date prescribed for 

increments promulgated in accordance 

with section 166(f) of the Act, upon 

which we based Options 2 and 3 for the 

annual PM2.5 increments. Thus, 

increments promulgated under Option 

1, which relies on the procedural 

provisions of section 166(b) of the Act, 

would normally be subject to a 1-year 

delay in implementation, while 

increments promulgated under either 

Option 2 or 3, relying on section 166(f) 

of the Act, could follow a 30- or 60-day 

effective date, typical of the effective 

date for most new rules in general. In 

either case, our consideration of the 

effective date for the PM2.5 increments 

assumed that the selected date would 

also be the effective date of the final 

rule. 

In the 2007 NPRM, we took comment 

on some alternative approaches to 

establishing the effective date for PM2.5

increments. Specifically, while 

proposing a 1-year effective date under 

Option 1, we requested comment on 

whether we could promulgate these 

increments under section 166(a) of the 

Act with an effective date of only 60 

days. See 72 FR 54142. 

Nine commenters supported our 

proposal to establish the effective date 

of the part 51 and 52 PSD regulations for 

PM2.5 as 1 year from the date of 

publication. Alternatively, two 

commenters encouraged us to apply the 

60-day effective date, while three other 

commenters supported other effective 

dates, as described in this section. 

Seven industry and industry 

association commenters supported our 

proposal to make the final rule for PM2.5

increments effective 1 year after 

promulgation. Most of these 

commenters cited the additional time 

necessary to develop the needed PM2.5

inventories needed for implementation 

of the PM2.5 PSD program. Two of the 

commenters urged EPA to allow State 

programs sufficient time to adopt 

increments, particularly if condensable 

particulate matter is included in the 

increment and its analysis. These 

commenters stated that the Federal rule 

should not be effective for 1 year. (They 

also stated that states should have 3 

years for the associated SIP revisions.) 

These same commenters added that this 

delay would provide time for sources 

that have permits in the pipeline or are 

just about to submit an application to be 

able to complete the permitting process 

without undue delay. One of the 

commenters specifically voiced support 

for Option 1 for the effective date of the 

final rule (1 year) and Option 2B for the 

period granted for SIP revisions (3 

years). This commenter also explained 

that this additional time may give the 

Agency time to promulgate better 

measurement methods for sources of 

condensable particulate matter. 

Another of these commenters noted 

that, at the time of the proposal, the 

NSR portion of the CAFPIR had not yet 

been promulgated, and that states would 

need time to incorporate that rule as 

well as the requirements of the proposal 

into their SIPs. This commenter added 

that making the PM2.5 increments 

effective before states and sources have 

had a reasonable opportunity to begin, 

let alone complete, the SIP process for 

the two related rulemakings would 

unnecessarily complicate an alreadycomplex regulatory process. 

In contrast, the two commenters 

supporting the shorter effective date 

encouraged us to apply the 60-day 

period for the effective date under 

whatever option is finalized. One of 

these commenters urged us to take 

measures to expedite the 


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implementation of the PM2.5 final rule 

and suggested that we choose the 

shortest of the proposed effective dates 

which are allowed under any of the 

applicable regulations. This commenter 

indicated that in light of the excessive 

delay in the implementation of the 

PM2.5 PSD program since the NAAQS 

were promulgated, the 60-day effective 

date should be applied under EPA’s 

preferred option. 

In light of our decision to promulgate 

PM2.5 increments under the authority of 

section 166(a) of the Act (proposed 

Option 1), we are faced with the 

decision as to how to most effectively 

implement the long-awaited PM2.5

increments, recognizing that the Act 

provides for a 1-year implementation 

delay. We have concluded that it is most 

appropriate to follow the plain language 

of the Act which calls for a 1-year 

effective date for implementing 

increments developed under section 

166(a) of the Act. We agree with the 

commenters who suggested that a 

shortened implementation delay was 

desirable because of the substantial 

delay in the promulgation of measures 

to prevent significant air quality 

deterioration with respect to PM2.5. 

Nevertheless, we believe it would be 

inappropriate in this action to disregard 

the statutory language which plainly 

calls for a 1-year delay. Accordingly, we 

are setting the effective date of the PM2.5

increments at 1 year from the date of 

promulgation of this final rule, 

consistent with the 1-year delay 

required under section 166(b) of the Act. 

We are doing this by setting the ‘‘trigger 

date’’ for PM2.5 as October 20, 2011. See 

new 40 CFR 51.166(b)(14)(i)(c) and 

(ii)(c), and new 40 CFR 52.21(b)(14)(i)(c) 

and (ii)(c). At the same time, we are 

establishing an effective date for the 

other provisions, i.e., the SILs and SMC 

for PM2.5, in this final rule as December 

20, 2010. This will enable the 

implementation of these key elements of 

this rule under the Federal PSD program 

as soon as possible. 

1. State PSD Programs 

In this final rule, we are establishing 

the final PM2.5 increments as minimum 

program elements for all State PSD 

programs. Accordingly, states must 

submit for EPA’s approval revised SIPs 

that incorporate the final PM2.5

increments or alternative measures that 

can be demonstrated to EPA’s 

satisfaction to provide an equivalent 

level of protection as the PM2.5

increments. In accordance with section 

166(b) of the Act, we are requiring states 

to submit revised implementation plans 

to EPA for approval within 21 months 

of promulgation, that is, by July 20, 

2012. Section 166(b) also specifies that 

we must approve or disapprove these 

revisions within 25 months of 

promulgation (4 months from the 

statutory deadline for SIP submittal). 

We regard these statutory deadlines as 

maximum allowed timeframes for 

action. Moreover, we do not believe that 

the Act restricts our ability to approve 

SIP revisions requested by a State at any 

time before these deadlines. In this final 

rule, we are amending the regulatory 

provisions at 40 CFR 51.166(a)(6)(i) to 

articulate the deadline set forth by the 

statute for the SIP submittals involving 

the PM2.5 increments pursuant to 

section 166(a) of the Act. 

It is very unlikely that states will be 

able to revise their SIPs and submit 

them to EPA for approval prior to the 

applicability date of the PM2.5

increments in this final rule, which is 

October 20, 2011. Therefore, there is 

likely to be a period of time after 

October 20, 2010 when State laws will 

not require PSD applicants otherwise 

subject to PSD for PM2.5 to complete an 

increment analysis for the PM2.5

increments, even though the PM2.5

increments, major source baseline date, 

and trigger date have been established 

as a result of this final rule. Similarly, 

it is not clear whether states will have 

the authority to consider such 

applicants as having triggered the minor 

source baseline date during this interim 

period before their revised PSD rules 

containing the PM2.5 increments and 

relevant baseline dates become effective. 

The EPA does not intend to prescribe 

the implementation timeline for State 

programs; rather, each State will need to 

determine how increment consumption 

and the setting of the minor source 

baseline date for PM2.5 will occur under 

its own PSD program. Nevertheless, 

regardless of when a State begins to 

require PM2.5 increment analyses and 

how it chooses to set the PM2.5 minor 

source baseline date, the emissions from 

sources subject to PSD for PM2.5 on 

which construction commenced after 

October 20, 2010 (the major source 

baseline date) will consume PM2.5

increment and must be included in 

increment analyses occurring after the 

minor source baseline date is 

established for an area under the State’s 

revised PSD program. 

2. Federal PSD Program 

The Federal PSD regulations under 40 

CFR 52.21 apply where states do not 

have approved PSD programs and in 

Indian lands. In such cases, either EPA 

implements the PSD program or the 

State will implement it under authority 

granted by EPA through a delegation 

agreement. 

We proposed to begin implementing 

the Federal PSD program for PM2.5 on 

the effective date of the final rule, i.e., 

either 1 year from the date of 

publication in the Federal Register or 

60 days from date of publication, if we 

developed the PM2.5 increments 

pursuant to proposed Option 1. 

Alternatively, we requested comment on 

whether we should delay 

implementation of the Federal PSD 

program until 25 months after 

promulgation, which is the latest date 

by which EPA is required to approve 

State SIP revisions. This is the same 

approach we took in 1988 to implement 

the then new NO2 increments. See 53 

FR 40658. We did not propose the 24- 

month delay for the PM2.5 increments 

because of the significant delay that has 

already occurred between the time we 

promulgated the PM2.5 NAAQS and the 

time the PM2.5 increment rulemaking 

would be finalized. However, we sought 

comment on this alternative approach 

because we recognized that it might not 

be equitable to begin implementation of 

the new program requirements in those 

few areas where the Federal program 

applies before the majority of states are 

required to implement the program. 

Two commenters urged EPA to hold 

off implementation of State programs 

administered under the Federal PSD 

program in order to provide a uniform 

and consistent national approach. One 

State agency supported implementing 

the Federal PSD program with a delayed 

effective date of 1 year after the effective 

date of the final rule instead of 60 days. 

We have decided to begin 

implementing the revised Federal PSD 

program as set out previously in our 

introductory discussion of this issue in 

section VIII.A. That is, the revised 

regulations at 40 CFR 52.21 will become 

effective in 60 days, on December 20, 

2010. This will allow EPA or the 

delegated State agency to begin using 

the SILs and SMC for PM2.5 on that date, 

as described in section VIII.C of this 

preamble. However, the date established 

in the regulations for the trigger date 

will ensure that the PM2.5 increments do 

not become effective for 1 year, 

consistent with section 166(b) of the 

Act, and that the minor source baseline 

date cannot be established until the 

PM2.5 increments become effective. 

However, PSD sources subject to PM2.5

that receive their PSD permit after the 

date of publication of this final rule will 

be considered to consume PM2.5

increments by virtue of the fact that they 

will commence construction after the 

major source baseline date for PM2.5, 

which is the date of publication of this 

final rule. 


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Thus, sources in an area subject to the 

Federal PSD program for PM2.5 will be 

able to use the SILs and SMC as 

screening tools for the required PM2.5

NAAQS compliance demonstration, but 

in most cases will not be required to 

submit a PM2.5 increment analysis as 

part of a complete PSD permit 

application for a Federal PSD permit 

unless the application is submitted on 

or after October 20, 2011. On or after 

that date, when an applicant submits a 

complete PSD permit application that is 

required to address PM2.5 under the 

Federal PSD program, that first 

application will establish the minor 

source baseline date for PM2.5 in the 

applicable attainment or unclassifiable 

area. 

As with the State PSD program 

requirements, prior to the establishment 

of the minor source baseline date in an 

area, emissions increases from minor 

sources in the area will be counted 

toward the baseline concentration, 

rather than to the PM2.5 increment. As 

described earlier, the emissions from 

major stationary sources that commence 

construction after the major source 

baseline date, regardless of the date on 

which their PSD application is 

submitted, must be counted toward 

consumption of the PM2.5 increments. 

While these sources will not be required 

to submit an increment analysis for 

PM2.5 as part of their complete 

application as long as they receive their 

PSD permit before the trigger date for 

PM2.5 (see discussion that follows in 

section VIII.B), the emissions increases 

resulting from the permitting of these 

sources ultimately must be counted 

toward the PM2.5 increments when the 

first PSD permit application submitted 

after the trigger date establishes the 

minor source baseline date for the area 

of concern, and in all subsequent PM2.5

increment analyses for that area. 

B. Transition Period 

In the 2007 NPRM, we proposed a 

transition period to clarify when PSD 

permit applications must contain an 

increment analysis demonstrating 

compliance with the PM2.5 increments 

following the date the PM2.5 increments 

become effective in any State or Federal 

PSD program. Specifically, we proposed 

to establish a grandfathering provision 

to allow complete applications 

submitted before the increment effective 

date, but for which the permit had not 

yet been issued by the effective date, to 

continue being processed using the 

PM10 Surrogate Policy to satisfy the 

requirement to demonstrate compliance 

with the new PM2.5 requirements. The 

grandfathering provision for PM2.5 was 

originally proposed in the 2007 NPRM 

at 40 CFR 51.166(i)(10) and 40 CFR 

52.21(i)(11) for State and Federal PSD 

programs, respectively. See 72 FR 54149 

and 54154. 

Three commenters supported the 

proposed grandfathering provision for 

sources that submitted a complete 

application before the effective date of 

the applicable PSD rules. Another 

commenter felt that it was reasonable to 

allow states a choice between using 

PM10 or PM2.5 increments during a 

transition period including SIP 

approval, where applicable. 

During the time since the proposal of 

this rule in 2007, we have reconsidered 

the need for the proposed transition 

period in the Federal PSD program to 

effectively implement the PM2.5

increments. In light of the importance of 

preventing significant deterioration of 

PM2.5 air quality and the amount of time 

that has passed since the initial 

promulgation of the PM2.5 NAAQS, we 

do not believe that further delay is 

warranted. We expect that most permits 

issued after October 20, 2011 will be 

from sources that submitted their PSD 

applications after the major source 

baseline date for PM2.5, which is defined 

as the date of publication of this final 

rule, so that they will be incrementconsuming sources. Therefore, when 

these sources apply for their PSD 

permits, they will have had significant 

advance notice of when the PM2.5

increments will become effective, i.e., 1 

year from the date of publication of this 

final rule. The review and permitting of 

permit applications submitted prior to 

the publication date of this final rule 

should generally be completed prior to 

the effective date of PM2.5 increments 

and thus effectively have a transition 

period of 1 year to complete processing. 

Thus, we are requiring each source 

that receives its PSD permit after the 

effective date of the PM2.5 increments, 

regardless of when the application was 

submitted, to provide a demonstration 

that the source’s proposed emissions 

increase, along with other incrementconsuming emissions, will not cause or 

contribute to a violation of the PM2.5

increments. 

Under this final rule, sources 

applying for a PSD permit under the 

Federal PSD program after the major 

source baseline date for PM2.5 (i.e., after 

the date of publication of this final rule), 

but before the PM2.5 increments become 

effective (i.e., the date 1 year after 

publication of this final rule), will be 

considered to consume PM2.5 increment. 

While EPA will not require any such 

source to include a PM2.5 increment 

analysis as part of its initial PSD 

application, an increment analysis 

ultimately will be required before the 

permit may be issued if the date of 

issuance will occur after the trigger date, 

when the PM2.5 increments become 

effective under the Federal PSD 

program. 

Finally, for the same reasons that we 

are not adopting the proposed transition 

period that would have exempted PSD 

applicants with pending permit 

applications from demonstrating 

compliance with the PM2.5 increment 

requirements under the Federal PSD 

program, we have decided not to 

provide an option for states to apply a 

transition period under 40 CFR 51.166. 

We believe it is appropriate for all 

increment-consuming sources subject to 

PM2.5 to demonstrate compliance with 

the PM2.5 increments when the required 

permit is issued after the PM2.5

increments become effective in the 

State’s PSD regulations. 

C. SILs and SMC for PM2.5

In the 2007 NPRM, we explained our 

position that SILs and SMCs are not 

minimum required elements of an 

approvable SIP. While these de minimis 

values are widely considered to be 

useful components for implementing 

the PSD program, they are not 

absolutely necessary for the states to 

implement their PSD programs. That is, 

states can satisfy the statutory 

requirements for a PSD program by 

requiring each PSD applicant to submit 

air quality monitoring data and to 

conduct a comprehensive air quality 

impacts analysis for PM2.5 without using 

de minimis thresholds to exempt certain 

sources from such requirements. 

Because the de minimis values for PM2.5

(and other pollutants) are not mandatory 

elements, we proposed not to establish 

specific deadlines for submitting 

revisions to incorporate the specific 

values for PM2.5 into SIPs. 

One State/local commenter agreed 

that the SILs and SMCs should not be 

a required element of the PSD SIP. 

Another State/local commenter agreed 

with our proposal, but stated that EPA 

has the authority to include SILs and 

SMCs as minimum program 

requirements per the opinion set forth 

in Alabama Power. This commenter 

added that the EPA Environmental 

Appeals Board has affirmed EPA’s 

interpretation of the Act to allow EPA 

to evaluate the significance of a source’s 

impact when determining whether the 

source’s emissions would ‘‘cause or 

contribute’’ to a NAAQS or increments 

violation under section 165(a)(3) of the 

Act. 

Two commenters disagreed with our 

proposed position and argued that SILs 

and SMCs should be mandatory 

elements of a State PSD program. One 


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of these commenters argued that the 

requirement to model without the use of 

screening models with SILs and SMCs 

is so unreasonable that EPA must 

require that states adopt the SILs and 

SMCs to meet the Purpose clause of the 

Act, which requires a balancing of 

environmental and economic 

considerations. The other opposing 

commenter stated that the increments, 

SILs, and SMCs need to be adopted as 

a single regulatory approach because the 

SILs and SMCs define when additional 

work is needed to ensure that PSD 

requirements, such as maintaining 

adequate increment, are met. This 

commenter added that there is no 

reason for sources to be placed in the 

position of conducting expensive 

modeling that can delay a project when 

it is unnecessary from an air quality 

perspective. 

We agree that the SILs and SMCs used 

as de minimis thresholds for the various 

pollutants are useful tools that enable 

permitting authorities and PSD 

applicants to screen out ‘‘insignificant’’ 

activities; however, the fact remains that 

these values are not required by the Act 

as part of an approvable SIP program. 

We believe that most states are likely to 

adopt the SILs and SMCs because of the 

useful purpose they serve regardless of 

our position that the values are not 

mandatory. Alternatively, states may 

develop more stringent values if they 

desire to do so. In any case, states are 

not under any SIP-related deadline for 

revising their PSD programs to add 

these screening tools. 

Using the SILs for PM2.5, when a 

proposed major new source or major 

modification of PM2.5 predicts (via air 

quality modeling) an impact less than 

the PM2.5 de minimis value, the 

proposed source or modification is not 

considered to have a significant air 

quality impact and would not need to 

complete a cumulative impact analysis 

involving an analysis of other sources in 

the area. Also, a source with a de 

minimis ambient impact would not be 

considered to cause or contribute to a 

violation of either the PM2.5 NAAQS or 

increments. 

The PM2.5 SILs will become effective 

under the Federal PSD program on the 

effective date of this final rule, that is, 

on December 20, 2010, when either 

EPA, or a State acting under a 

delegation of EPA’s authority, 

implements the revised PSD permitting 

requirements for PM2.5 pursuant to 40 

CFR 52.21. The SILs will be for use 

initially with the compliance 

demonstration for the PM2.5 NAAQS, 

and later for the PM2.5 increment 

analysis, under the Federal PSD 

program. We emphasize, however, that 

the PM2.5 SILs are not intended to be 

used as part of the determination of 

adverse impacts on AQRVs for PM2.5 in 

Class I areas. 

Similarly, we intend to use the PM2.5

SMC (4 μg/m3, 24-hour average) as a 

screening tool in the Federal PSD permit 

program beginning on December 20, 

2010. Accordingly, when either the 

modeled PM2.5 impact of, or the existing 

ambient air quality within the area of, 

the proposed new major source or major 

modification is less than the PM2.5 SMC, 

the reviewing authority may exempt the 

source or modification from the 

monitoring data requirements for PM2.5

under 40 CFR 52.21(m). 

IX. Other Regulatory Changes 

The Act provides that the PSD 

regulations apply to areas designated as 

‘‘attainment’’ or ‘‘unclassifiable’’ as 

defined by the Act. When the original 

regulations were written, the Act 

provisions for designating areas as 

either ‘‘attainment’’ or ‘‘unclassifiable’’ 

were contained in sections 107(d)(1)(D) 

and (E), respectively. In 1990, Congress 

revised section 107 and changed the 

relevant paragraphs defining 

‘‘attainment’’ and ‘‘unclassifiable’’ areas 

to sections 107(d)(1)(A)(ii) and (iii), 

respectively. In accordance with these 

statutory changes, we are correcting the 

references to the statutory classifications 

contained in the existing PSD rules to 

match the revised paragraphs in the Act. 

See revised 40 CFR 51.166(b)(14)(iii)(a) 

and (15)(i) and (ii), and 40 CFR 

52.21(b)(14)(iii)(a) and (15)(i) and (ii). 

In adding the SILs for PM2.5 in this 

final rule, we restructured paragraph (k) 

(‘‘Source impact analysis’’) in the 

existing PSD regulations at 40 CFR 

51.166 and 52.21. Under the 

restructuring of paragraph (k), old 

paragraph (k)(2) is now paragraph 

(k)(1)(ii). To accommodate this 

restructuring change, we are also 

revising grandfathering provisions that 

are contained in existing paragraphs 

(i)(8) and (i)(9) at 40 CFR 51.166, and 

paragraphs (i)(9) and (i)(10) at 40 CFR 

52.21, which contained references to 

requirements contained in paragraph 

(k)(2). As revised, the grandfathering 

provisions now reference new 

paragraph (k)(1)(ii). 

X. Statutory and Executive Order 

Reviews 

A. Executive Order 12866—Regulatory 

Planning and Review 

Under Executive Order 12866 (58 FR 

51735, October 4, 1993), this action is a 

‘‘significant regulatory action’’ because it 

raises novel legal or policy issues 

arising out of legal mandates, the 

President’s priorities, or the principle 

set forth in the Executive Order. 

Accordingly, EPA submitted this action 

to OMB for review under Executive 

Order 12866 and any changes made in 

response to OMB recommendations 

have been documented in the docket for 

this action. 

B. Paperwork Reduction Act 

The information collection 

requirements in this rule have been 

submitted for approval to the OMB 

under the Paperwork Reduction Act, 44 

U.S.C. 3501 et seq. The information 

collection requirements are not 

enforceable until OMB approves them. 

Pursuant to title I, part C, of the Act, 

the PSD program requires the owner or 

operator to obtain a permit prior to 

either constructing a new major 

stationary source of air pollutants or 

making a major modification to an 

existing major stationary source. The 

information collection for sources under 

PSD results from the requirement for 

owners or operators to submit 

applications for NSR permits. In some 

cases, sources must conduct 

preconstruction monitoring to 

determine the existing ambient air 

quality. For reviewing authorities, the 

information collection results from the 

requirement to process permit 

applications and issue permits, and to 

transmit associated information to EPA. 

The EPA oversees the PSD program, and 

the information collected by sources 

and reviewing authorities is used to 

ensure that the program is properly 

implemented. 

The final rule will increase the PSD 

permitting burden for owners and 

operators of major stationary sources of 

PM2.5 emissions by adding PM2.5

increments to the list of existing 

increments for which air quality impact 

analyses must be carried out to track the 

amount of increment consumed by the 

proposed source and other sources in 

the area. Over the 3-year period covered 

by the ICR, we estimate an average 

annual burden totaling about 29,000 

hours and $2.8 million for all industry 

entities that will be affected by the final 

rule. For the same reasons, we also 

expect the final rule (when fully 

implemented) to increase burden for the 

State and local authorities reviewing 

PSD permit applications. In addition, 

there will be additional burden for State 

and local agencies to revise their SIPs to 

incorporate the proposed changes. Over 

the 3-year period covered by the ICR, we 

estimate that the average annual burden 

for all State and local reviewing 

authorities will total about 7,500 hours 

and $581,000. Burden is defined at 5 

CFR 1320.3(b). 


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An agency may not conduct or 

sponsor, and a person is not required to 

respond to, a collection of information 

unless it displays a currently valid OMB 

control number. The OMB control 

numbers for EPA’s regulations in 40 

CFR are listed in 40 CFR part 9. When 

this ICR is approved by OMB, the 

Agency will publish a technical 

amendment to 40 CFR part 9 in the 

Federal Register to display the OMB 

control number for the approved 

information collection requirements 

contained in this final rule. 

C. Regulatory Flexibility Act 

The Regulatory Flexibility Act (RFA) 

generally requires an agency to prepare 

a regulatory flexibility analysis of any 

rule subject to notice and comment 

rulemaking requirements under the 

Administrative Procedure Act or any 

other statute unless the Agency certifies 

that the rule will not have a significant 

economic impact on a substantial 

number of small entities. Small entities 

include small businesses, small 

organizations, and small governmental 

jurisdictions. 

For purposes of assessing the impacts 

of this rule on small entities, ‘‘small 

entity’’ is defined as: (1) A small 

business as defined by the Small 

Business Administration’s regulations at 

13 CFR 121.201; (2) a small 

governmental jurisdiction that is a 

government of a city, county, town, 

school district or special district with a 

population of less than 50,000; and (3) 

a small organization that is any not-forprofit enterprise which is independently 

owned and operated and is not 

dominant in its field. 

After considering the economic 

impacts of this final rule on small 

entities, I certify that this action will not 

have a significant economic impact on 

a substantial number of small entities. 

This final rule will not impose any 

requirements on small entities because 

small entities are not subject to the 

requirements of this rule. 

D. Unfunded Mandates Reform Act 

This action contains no Federal 

mandates under the provisions of Title 

II of the Unfunded Mandates Reform 

Act of 1995 (UMRA), 2 U.S.C. 1531– 

1538 for State, local, or tribal 

governments or the private sector. The 

action imposes no enforceable duty on 

any State, local or tribal governments or 

the private sector. The final rules adds 

only a relatively small number of new 

requirements to the existing permit 

requirements already in place under the 

PSD program, since states are currently 

implementing a PM10 surrogate program 

pursuant to EPA guidance. Thus, this 

action is not subject to the requirements 

of sections 202 or 205 of UMRA. 

This rule is also not subject to the 

requirements of section 203 of UMRA 

because it contains no regulatory 

requirements that might significantly or 

uniquely affect small governments. The 

final rule applies only to new major 

stationary sources and to major 

modifications at existing major 

stationary sources. 

E. Executive Order 13132—Federalism 

This final rule does not have 

federalism implications. It will not have 

substantial direct effects on the states, 

on the relationship between the national 

government and the states, or on the 

distribution of power and 

responsibilities among the various 

levels of government, as specified in 

Executive Order 13132. The final rule 

makes relatively minor changes to the 

established PSD program, simply 

making it possible for states to 

implement PSD for PM2.5 instead of 

relying on PM10 as a surrogate. Thus, 

Executive Order 13132 does not apply 

to this rule. In the spirit of Executive 

Order 13132, and consistent with EPA 

policy to promote communications 

between EPA and State and local 

governments, EPA specifically solicited 

comment on the proposed rule from 

State and local officials. 

F. Executive Order 13175—Consultation 

and Coordination With Indian Tribal 

Governments 

This action does not have tribal 

implications, as specified in Executive 

Order 13175 (65 FR 67249, November 9, 

2000). The final rule provides the 

elements to implement a PM2.5 PSD 

program in attainment areas. The Act 

provides for states to develop plans to 

regulate emissions of air pollutants 

within their jurisdictions. The Tribal 

Air Rule (TAR) under the Act gives 

tribes the opportunity to develop and 

implement Act programs to attain and 

maintain the PM2.5 NAAQS, but leaves 

to the discretion of the tribes the 

decision of whether to develop these 

programs and which programs, or 

appropriate elements of a program, they 

will adopt. Thus, Executive Order 13175 

does not apply to this action. 

The EPA did reach out to national 

tribal organizations in 2006 to provide 

a forum for tribal professionals to 

provide input to the rulemaking. 

However, not much participation or 

input was received. 

G. Executive Order 13045—Protection of 

Children From Environmental Health 

and Safety Risks 

This action is not subject to Executive 

Order 13045 (62 FR 19885, April 23, 

1997) because it is not economically 

significant as defined in Executive 

Order 12866, and because the Agency 

does not believe the environmental 

health or safety risks addressed by this 

action present a disproportionate risk to 

children. One of the basic requirements 

of the PSD program is that new and 

modified major sources must 

demonstrate that any new emissions do 

not cause or contribute to air quality in 

violation of the NAAQS. 

H. Executive Order 13211—Actions 

That Significantly Affect Energy Supply, 

Distribution, or Use 

This action is not a ‘‘significant energy 

action’’ as defined in Executive Order 

13211 (66 FR 28355, May 22, 2001) 

because it is not likely to have a 

significant adverse effect on the supply, 

distribution, or use of energy. Further, 

we have concluded that this rule is not 

likely to have any adverse energy 

effects. 

I. National Technology Transfer and 

Advancement Act 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (NTTAA), Public Law 104– 

113, 12(d) (15 U.S.C. 272 note) directs 

EPA to use voluntary consensus 

standards in its regulatory activities 

unless to do so would be inconsistent 

with applicable law or otherwise 

impractical. Voluntary consensus 

standards are technical standards (e.g., 

materials specifications, test methods, 

sampling procedures, and business 

practices) that are developed or adopted 

by voluntary consensus standards 

bodies. The NTTAA directs EPA to 

provide Congress, through OMB, 

explanations when the Agency decides 

not to use available and applicable 

voluntary consensus standards. 

This action does not involve technical 

standards. Therefore, EPA did not 

consider the use of any voluntary 

consensus standards. 

J. Executive Order 12898—Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations 

Executive Order 12898 (59 FR 7629, 

Feb. 16, 1994) establishes Federal 

executive policy on environmental 

justice. Its main provision directs 

Federal agencies, to the greatest extent 

practicable and permitted by law, to 

make environmental justice part of their 

mission by identifying and addressing, 


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as appropriate, disproportionately high 

and adverse human health or 

environmental effects of their programs, 

policies, and activities on minority 

populations and low-income 

populations in the United States. 

The EPA has determined that this 

final rule will not have 

disproportionately high and adverse 

human health or environmental effects 

on minority or low-income populations 

because it does not affect the level of 

protection provided to human health or 

the environment. This final rule will 

provide regulatory certainty for 

implementing the preconstruction NSR 

permitting program for PM2.5. However, 

the requirements are similar to the 

existing requirements of the PM10

program and hence do not impact the 

human health or environmental effects. 

K. Congressional Review Act 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. The EPA will 

submit a report containing this rule and 

other required information to the U.S. 

Senate, the U.S. House of 

Representatives, and the Comptroller 

General of the United States prior to 

publication of the rule in the Federal 

Register. A major rule cannot take effect 

until 60 days after it is published in the 

Federal Register. This action is not a 

‘‘major rule’’ as defined by 5 U.S.C. 

804(2). Nevertheless, this rule needs to 

be reviewed for the PM2.5 increments 

being promulgated herein so that they 

can be scrutinized by Congress as 

intended under section 166(b) of the 

Act. Even though the PM2.5 increments 

will not become applicable for 1 year, 

the final rule will become effective 60 

days from the date of publication, that 

is, on December 20, 2010, for the 

screening tools (SILs and SMC) being 

established in this rule. 

XI. Judicial Review 

Under section 307(b)(1) of the Act, 

petitions for judicial review of this 

action must be filed in the United States 

Court of Appeals for the District of 

Columbia Circuit by December 20, 2010. 

Any such judicial review is limited to 

only those objections that are raised 

with reasonable specificity in timely 

comments. Filing a petition for 

reconsideration by the Administrator of 

this final rule does not affect the finality 

of this rule for the purposes of judicial 

review nor does it extend the time 

within which a petition for judicial 

review may be filed, and shall not 

postpone the effectiveness of such rule 

or action. Under section 307(b)(2) of the 

Act, the requirements of this final action 

may not be challenged later in civil or 

criminal proceedings brought by us to 

enforce these requirements. 

XII. Statutory Authority 

The statutory authority for this final 

action is provided by sections 101, 160, 

163, 165, 166, 301, and 307(d) of the Act 

as amended (42 U.S.C. 7401, 7470, 7473, 

7475, 7476, 7601, and 7607(d)). 

List of Subjects 

40 CFR Part 51 

Administrative practices and 

procedures, Air pollution control, 

Environmental protection, 

Intergovernmental relations. 

40 CFR Part 52 

Administrative practices and 

procedures, Air pollution control, 

Environmental protection, 

Intergovernmental relations. 

Dated: September 30, 2010. 

Lisa P. Jackson, 

Administrator. 

■ For the reasons set out in the 

preamble, title 40, chapter I of the Code 

of Federal Regulations is amended as 

follows: 

PART 51—[AMENDED] 

■ 1. The authority citation for part 51 

continues to read as follows: 

Authority: 23 U.S.C. 101; 42 U.S.C. 7401– 

7671q. 

Subpart I—[Amended] 

■ 2. Section 51.165 is amended by 

revising the table in paragraph (b)(2) to 

read as follows: 

§ 51.165 Permit requirements. 

* * * * * 

(b) * * * 

(2) * * * 

Pollutant Annual 

Averaging time (hours) 

24 8 3 1 

SO2 ............................................................................................................... 1.0 μg/m3 5 μg/m3 25 μg/m3

PM10 .............................................................................................................. 1.0 μg/m3 5 μg/m3

PM2.5 ............................................................................................................. 0.3 μg/m3 1.2 μg/m3

NO2 ............................................................................................................... 1.0 μg/m3

CO ................................................................................................................ 0.5 mg/m3 2 mg/m3

* * * * * 

■ 3. Section 51.166 is amended as 

follows: 

■ a. By revising paragraph (a)(6)(i); 

■ b. By revising paragraph (b)(14)(i)(a); 

■ c. By removing the period at the end 

of paragraph (b)(14)(i)(b) and adding ‘‘; 

and’’ in its place; 

■ d. By adding paragraph (b)(14)(i)(c); 

■ e. By revising paragraph (b)(14)(ii)(a); 

■ f. By removing the period at the end 

of paragraph (b)(14)(ii)(b) and adding ‘‘; 

and’’ in its place; 

■ g. By adding paragraph (b)(14)(ii)(c); 

■ h. By revising paragraph (b)(14)(iii)(a); 

■ i. By revising paragraph (b)(15)(i) and 

paragraph (b)(15)(ii) introductory text; 

■ j. By revising the table in paragraph 

(c)(1); 

■ k. By revising paragraph (c)(2); 

■ l. By revising paragraph (i)(5)(i)(c); 

■ m. By redesignating existing 

paragraphs (i)(5)(i)(d) through (j) as 

paragraphs (i)(5)(i)(e) through (k); 

■ n. By adding new paragraph 

(i)(5)(i)(d); 

■ o. By removing ‘‘(k)(2)’’ from 

paragraph (i)(8) and adding ‘‘(k)(1)(ii)’’ in 

its place; 

■ p. By removing in two places ‘‘(k)(2)’’ 

from paragraph (i)(9) and adding 

‘‘(k)(1)(ii)’’ in those places; 

■ q. By revising paragraph (k); 

■ r. By removing the words ‘‘particulate 

matter’’ in the last sentence of paragraph 

(p)(4) introductory text and adding in 

their place ‘‘PM2.5, PM10’’; and 

■ s. By revising the table in paragraph 

(p)(4). 

§ 51.166 Prevention of significant 

deterioration of air quality. 

(a) * * * 

(6) * * * 


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(i) Any State required to revise its 

implementation plan by reason of an 

amendment to this section, with the 

exception of amendments to add new 

maximum allowable increases or other 

measures pursuant to section 166(a) of 

the Act, shall adopt and submit such 

plan revision to the Administrator for 

approval no later than 3 years after such 

amendment is published in the Federal 

Register. With regard to a revision to an 

implementation plan by reason of an 

amendment to paragraph (c) of this 

section to add maximum allowable 

increases or other measures, the State 

shall submit such plan revision to the 

Administrator for approval within 21 

months after such amendment is 

published in the Federal Register. 

* * * * * 

(b) * * * 

(14)(i) * * * 

(a) In the case of PM10 and sulfur 

dioxide, January 6, 1975; 

* * * * * 

(c) In the case of PM2.5, October 20, 

2010. 

(ii) * * * 

(a) In the case of PM10 and sulfur 

dioxide, August 7, 1977; 

* * * * * 

(c) In the case of PM2.5, October 20, 

2011. 

(iii) * * * 

(a) The area in which the proposed 

source or modification would construct 

is designated as attainment or 

unclassifiable under section 

107(d)(1)(A)(ii) or (iii) of the Act for the 

pollutant on the date of its complete 

application under 40 CFR 52.21 or 

under regulations approved pursuant to 

40 CFR 51.166; and 

* * * * * 

(15)(i) Baseline area means any 

intrastate area (and every part thereof) 

designated as attainment or 

unclassifiable under section 

107(d)(1)(A)(ii) or (iii) of the Act in 

which the major source or major 

modification establishing the minor 

source baseline date would construct or 

would have an air quality impact for the 

pollutant for which the baseline date is 

established, as follows: Equal to or 

greater than 1 μg/m3 (annual average) 

for SO2, NO2, or PM10; or equal or 

greater than 0.3 μg/m3 (annual average) 

for PM2.5. 

(ii) Area redesignations under section 

107(d)(1)(A)(ii) or (iii) of the Act cannot 

intersect or be smaller than the area of 

impact of any major stationary source or 

major modification which: 

* * * * * 

(c) * * * 

(1) * * * 

Pollutant 

Maximum 

allowable 

increase 

(micrograms 

per cubic 

meter) 

Class I Area 

PM2.5: 

Annual arithmetic mean ................................................................................................................................................................ 1 

24-hr maximum ............................................................................................................................................................................. 2 

PM10: 

Annual arithmetic mean ................................................................................................................................................................ 4 

24-hr maximum ............................................................................................................................................................................. 8 

Sulfur dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 2 

24-hr maximum ............................................................................................................................................................................. 5 

3-hr maximum ............................................................................................................................................................................... 25 

Nitrogen dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 2.5 

Class II Area 

PM2.5: 

Annual arithmetic mean ................................................................................................................................................................ 4 

24-hr maximum ............................................................................................................................................................................. 9 

PM10: 

Annual arithmetic mean ................................................................................................................................................................ 17 

24-hr maximum ............................................................................................................................................................................. 30 

Sulfur dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 20 

24-hr maximum ............................................................................................................................................................................. 91 

3-hr maximum ............................................................................................................................................................................... 512 

Nitrogen dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 25 

Class III Area 

PM2.5: 

Annual arithmetic mean ................................................................................................................................................................ 8 

24-hr maximum ............................................................................................................................................................................. 18 

PM10: 

Annual arithmetic mean ................................................................................................................................................................ 34 

24-hr maximum ............................................................................................................................................................................. 60 

Sulfur dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 40 

24-hr maximum ............................................................................................................................................................................. 182 

3-hr maximum ............................................................................................................................................................................... 700 

Nitrogen dioxide: 


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Pollutant 

Maximum 

allowable 

increase 

(micrograms 

per cubic 

meter) 

Annual arithmetic mean ................................................................................................................................................................ 50 

* * * * * 

(2) Where the State can demonstrate 

that it has alternative measures in its 

plan other than maximum allowable 

increases as defined under paragraph 

(c)(1) of this section, that satisfy the 

requirements in sections 166(c) and 

166(d) of the Clean Air Act for a 

regulated NSR pollutant for which the 

Administrator has established 

maximum allowable increases pursuant 

to section 166(a) of the Act, the 

requirements for maximum allowable 

increases for that pollutant under 

paragraph (c)(1) of this section shall not 

apply upon approval of the plan by the 

Administrator. The following regulated 

NSR pollutants are eligible for such 

treatment: 

(i) Nitrogen dioxide. 

(ii) PM2.5. 

* * * * * 

(i) * * * 

(5) * * * 

(i) * * * 

(c) PM2.5–4 μg/m3, 24-hour average; 

(d) PM10–10 μg/m3, 24-hour average; 

* * * * * 

(k) Source impact analysis—(1) 

Required demonstration. The plan shall 

provide that the owner or operator of 

the proposed source or modification 

shall demonstrate that allowable 

emission increases from the proposed 

source or modification, in conjunction 

with all other applicable emissions 

increases or reduction (including 

secondary emissions), would not cause 

or contribute to air pollution in 

violation of: 

(i) Any national ambient air quality 

standard in any air quality control 

region; or 

(ii) Any applicable maximum 

allowable increase over the baseline 

concentration in any area. 

(2) Significant impact levels. The plan 

may provide that, for purposes of PM2.5, 

the demonstration required in paragraph 

(k)(1) of this section is deemed to have 

been made if the emissions increase 

from the new stationary source alone or 

from the modification alone would 

cause, in all areas, air quality impacts 

less than the following amounts: 

Pollutant Averaging time Class I 

area 

Class II 

area 

Class III 

area 

PM2.5 .................................................................... Annual .................................................................. 0.06 μg/m3 0.3 μg/m3 0.3 μg/m3

24-hour ................................................................. 0.07 μg/m3 1.2 μg/m3 1.2 μg/m3

* * * * * 

(p) * * * 

(4) * * * 

Pollutant 

Maximum 

allowable 

increase 

(micrograms 

per cubic 

meter) 

PM2.5: 

Annual arithmetic mean ................................................................................................................................................................ 4 

24-hr maximum ............................................................................................................................................................................. 9 

PM10: 

Annual arithmetic mean ................................................................................................................................................................ 17 

24-hr maximum ............................................................................................................................................................................. 30 

Sulfur dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 20 

24-hr maximum ............................................................................................................................................................................. 91 

3-hr maximum ............................................................................................................................................................................... 325 

Nitrogen dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 25 

* * * * * 

■ 4. Appendix S to part 51 is amended 

by revising the table in section III.A to 

read as follows: 

Appendix S to Part 51—Emission Offset 

Interpretative Ruling 

* * * * * 

III. * * * 

A. * * * 

Pollutant Annual 

Averaging time (hours) 

24 8 3 1 

SO2 ........................................................................ 1.0 μg/m3 5 μg/m3 25 μg/m3

PM10 ...................................................................... 1.0 μg/m3 5 μg/m3


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Pollutant Annual 

Averaging time (hours) 

24 8 3 1 

PM2.5 ...................................................................... 0.3 μg/m3 1.2 μg/m3

NO2 ........................................................................ 1.0 μg/m3

CO ......................................................................... 0.5 mg/m3 2 mg/m3

* * * * * 

PART 52—[AMENDED] 

■ 1. The authority citation for part 52 

continues to read as follows: 

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

Subpart A—[Amended] 

■ 2. Section 52.21 is amended as 

follows: 

■ a. By revising paragraph (b)(14)(i)(a); 

■ b. By removing the period at the end 

of paragraph (b)(14)(i)(b) and adding ‘‘; 

and’’ in its place; 

■ c. By adding paragraph (b)(14)(i)(c); 

■ d. By revising paragraph (b)(14)(ii)(a); 

■ e. By removing the period at the end 

of paragraph (b)(14)(ii)(b) and adding ‘‘; 

and’’ in its place; 

■ f. By adding paragraph (b)(14)(ii)(c); 

■ g. By revising paragraph (b)(14)(iii)(a); 

■ h. By revising paragraph (b)(15)(i) and 

paragraph (b)(15)(ii) introductory text; 

■ i. By revising the table in paragraph 

(c); 

■ j. By revising paragraph (i)(5)(i); 

■ k. By removing ‘‘(k)(2)’’ from 

paragraph (i)(9) and adding ‘‘(k)(1)(ii)’’ in 

its place; 

■ l. By removing in two places ‘‘(k)(2)’’ 

from paragraph (i)(10) and adding 

‘‘(k)(1)(ii)’’ in those places; 

■ m. By revising paragraph (k); 

■ n. By removing the words ‘‘particulate 

matter’’ in the last sentence of paragraph 

(p)(5) introductory text and adding in 

their place ‘‘PM2.5, PM10’’; and 

■ o. By revising the table in paragraph 

(p)(5). 

§ 52.21 Prevention of significant 

deterioration of air quality. 

* * * * * 

(b) * * * 

(14)(i) * * * 

(a) In the case of PM10 and sulfur 

dioxide, January 6, 1975; 

* * * * * 

(c) In the case of PM2.5, October 20, 

2010. 

(ii) * * * 

(a) In the case of PM10 and sulfur 

dioxide, August 7, 1977; 

* * * * * 

(c) In the case of PM2.5, October 20, 

2011. 

(iii) * * * 

(a) The area in which the proposed 

source or modification would construct 

is designated as attainment or 

unclassifiable under section 

107(d)(1)(A)(ii) or (iii) of the Act for the 

pollutant on the date of its complete 

application under 40 CFR 52.21 or 

under regulations approved pursuant to 

40 CFR 51.166; and 

* * * * * 

(15)(i) Baseline area means any 

intrastate area (and every part thereof) 

designated as attainment or 

unclassifiable under section 

107(d)(1)(A)(ii) or (iii) of the Act in 

which the major source or major 

modification establishing the minor 

source baseline date would construct or 

would have an air quality impact for the 

pollutant for which the baseline date is 

established, as follows: equal to or 

greater than 1 μg/m3 (annual average) 

for SO2, NO2, or PM10; or equal or 

greater than 0.3 μg/m3 (annual average) 

for PM2.5. 

(ii) Area redesignations under section 

107(d)(1)(A)(ii) or (iii) of the Act cannot 

intersect or be smaller than the area of 

impact of any major stationary source or 

major modification which: 

* * * * * 

(c) * * * 

Pollutant 

Maximum 

allowable 

increase 

(micrograms 

per cubic 

meter) 

Class I Area 

PM2.5: 

Annual arithmetic mean ................................................................................................................................................................ 1 

24-hr maximum ............................................................................................................................................................................. 2 

PM10: 

Annual arithmetic mean ................................................................................................................................................................ 4 

24-hr maximum ............................................................................................................................................................................. 8 

Sulfur dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 2 

24-hr maximum ............................................................................................................................................................................. 5 

3-hr maximum ............................................................................................................................................................................... 25 

Nitrogen dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 2.5 

Class II Area 

PM2.5: 

Annual arithmetic mean ................................................................................................................................................................ 4 

24-hr maximum ............................................................................................................................................................................. 9 

PM10: 

Annual arithmetic mean ................................................................................................................................................................ 17 

24-hr maximum ............................................................................................................................................................................. 30 

Sulfur dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 20 


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VI-137 A-187
64906 Federal Register / Vol. 75, No. 202 / Wednesday, October 20, 2010 / Rules and Regulations 

Pollutant 

Maximum 

allowable 

increase 

(micrograms 

per cubic 

meter) 

24-hr maximum ............................................................................................................................................................................. 91 

3-hr maximum ............................................................................................................................................................................... 512 

Nitrogen dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 25 

Class III Area 

PM2.5: 

Annual arithmetic mean ................................................................................................................................................................ 8 

24-hr maximum ............................................................................................................................................................................. 18 

PM10: 

Annual arithmetic mean ................................................................................................................................................................ 34 

24-hr maximum ............................................................................................................................................................................. 60 

Sulfur dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 40 

24-hr maximum ............................................................................................................................................................................. 182 

3-hr maximum ............................................................................................................................................................................... 700 

Nitrogen dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 50 

* * * * * 

(i) * * * 

(5) * * * 

(i) The emissions increase of the 

pollutant from the new source or the net 

emissions increase of the pollutant from 

the modification would cause, in any 

area, air quality impacts less than the 

following amounts: 

(a) Carbon monoxide—575 μg/m3, 

8-hour average; 

(b) Nitrogen dioxide—14 μg/m3, 

annual average; 

(c) PM2.5—4 μg/m3, 24-hour average; 

(d) PM10—10 μg/m3, 24-hour average; 

(e) Sulfur dioxide—13 μg/m3, 24-hour 

average; 

(f) Ozone; 

(g) Lead—0.1 μg/m3, 3-month average; 

(h) Fluorides—0.25 μg/m3, 24-hour 

average; 

(i) Total reduced sulfur—10 μg/m3, 

1-hour average; 

(j) Hydrogen sulfide—0.2 μg/m3, 

1-hour average; 

(k) Reduced sulfur compounds— 

10 μg/m3, 1-hour average; or 

Note to paragraph (c)(50)(i)(f): No de 

minimis air quality level is provided for 

ozone. However, any net emissions increase 

of 100 tons per year or more of volatile 

organic compounds or nitrogen oxides 

subject to PSD would be required to perform 

an ambient impact analysis, including the 

gathering of ambient air quality data. 

* * * * * 

(k) Source impact analysis—(1) 

Required demonstration. The owner or 

operator of the proposed source or 

modification shall demonstrate that 

allowable emission increases from the 

proposed source or modification, in 

conjunction with all other applicable 

emissions increases or reductions 

(including secondary emissions), would 

not cause or contribute to air pollution 

in violation of: 

(i) Any national ambient air quality 

standard in any air quality control 

region; or 

(ii) Any applicable maximum 

allowable increase over the baseline 

concentration in any area. 

(2) Significant impact levels. For 

purposes of PM2.5, the demonstration 

required in paragraph (k)(1) of this 

section is deemed to have been made if 

the emissions increase from the new 

stationary source alone or from the 

modification alone would cause, in all 

areas, air quality impacts less than the 

following amounts: 

Pollutant Averaging time Class I 

area 

Class II 

area 

Class III 

area 

PM2.5 ................................................................... Annual ................................................................. 0.06 μg/m3 0.3 μg/m3 0.3 μg/m3

............................................................................. 24-hour ................................................................ 0.07 μg/m3 1.2 μg/m3 1.2 μg/m3

* * * * * (p) * * * 


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VI-138 A-188
Federal Register / Vol. 75, No. 202 / Wednesday, October 20, 2010 / Rules and Regulations 64907 

(5) * * * 

Pollutant 

Maximum 

allowable 

increase 

(micrograms 

per cubic 

meter) 

PM2.5: 

Annual arithmetic mean ................................................................................................................................................................ 4 

24-hr maximum ............................................................................................................................................................................. 9 

PM10: 

Annual arithmetic mean ................................................................................................................................................................ 17 

24-hr maximum ............................................................................................................................................................................. 30 

Sulfur dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 20 

24-hr maximum ............................................................................................................................................................................. 91 

3-hr maximum ............................................................................................................................................................................... 325 

Nitrogen dioxide: 

Annual arithmetic mean ................................................................................................................................................................ 25 

* * * * * 

[FR Doc. 2010–25132 Filed 10–19–10; 8:45 am] 

BILLING CODE 6560–50–P 


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VI-139 A-189
Federal Register Notices Not Included in Hearing Record 

1. Implementation of the New Source Review (NSR) Program for Particulate Matter Less 

Than 2.5 Micrometers (PM2.5); Final Rule To Repeal Grandfather Provision, 76 FR 

28646, May 18, 2011, http://www.gpo.gov/fdsys/pkg/FR-2011-05-18/pdf/2011-

12089.pdf. 

2. Implementation of the New Source Review (NSR) Program for Particulate Matter Less 

Than 2.5 Micrometers (PM2.5): Amendment to the Definition of ‘‘Regulated NSR 

Pollutant’’ Concerning Condensable Particulate Matter, 77 FR 65107, October 25, 2012, 

http://www.gpo.gov/fdsys/pkg/FR-2012-10-25/pdf/2012-25978.pdf. 

VI-140 A-190
VII-1 

Chapter VII 

The following documentation of filing and notification is incorporated as part of this hearing record and is 

maintained on file: 

1. ENR 101 Internal Approval Form. 

2. Submission for Notice Form and material submitted to the Office of Administrative 

Hearings. 

3. The public notice as it appears in The North Carolina Register Volume 27, Issue 11, 

pages 1013-1020. 

4. Letters to newspapers requesting that the public notice be published. 

5. Affidavits of Publication from newspaper. 

6. Memorandum transmitting hearing notice and proposal to regional offices for public 

inspection. 

7. Memorandum transmitting hearing notice and proposal to local programs. 

8. Letter notifying EPA of hearing. 

9. Submission of Filing Forms and material filed with Office of Administrative Hearings. 

 10. Letter transmitting hearing record to EPA. 

11. Executive Order No. 70 Certification Form 

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VII-2 

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