Air Plan Approval; Delaware; 2006 24-Hour Fine Particulate Matter Limited Maintenance Plan for the Philadelphia Nonattainment Area

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R03-OAR-2025-0205; FRL-11969-02-R3]

Air Plan Approval; Delaware; 2006 24-Hour Fine Particulate Matter Limited Maintenance Plan for the Philadelphia Nonattainment Area

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Final rule.

SUMMARY:

The Environmental Protection Agency (EPA) is approving a state implementation plan (SIP) revision submitted by the State of Delaware through the Delaware Department of Natural Resources and Environmental Control (DNREC). The revision pertains to the second 10-year limited maintenance plan (LMP) for the 2006 24-hour fine particulate matter (PM

2.5

) national ambient air quality standard (NAAQS). The LMP addresses the New Castle County portion of the Philadelphia-Wilmington, PA-NJ-DE Area. The EPA is approving the LMP because it provides for the maintenance of the 2006 24-hour PM

2.5

NAAQS through the end of the second 10-year maintenance period. In addition, the EPA is finalizing the process to find the LMP adequate for transportation conformity purposes. The EPA is approving this revision to the Delaware SIP in accordance with the requirements of the Clean Air Act (CAA).

DATES:

This final rule is effective on August 3, 2026.

ADDRESSES:

The EPA has established a docket for this action under Docket ID Number EPA-R03-OAR-2025-0205. All documents in the docket are listed on the

www.regulations.gov

website. Although listed in the index, some information is not 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 through

www.regulations.gov

, or please contact the person identified in the

FOR FURTHER INFORMATION CONTACT

section for additional availability information.

FOR FURTHER INFORMATION CONTACT:

Sarah McCabe, Planning & Implementation Branch (3AD30), Air & Radiation Division, U.S. Environmental Protection Agency, Region III, 1600 John F Kennedy Boulevard, Philadelphia, Pennsylvania 19103. The telephone number is (215) 814-5786. Ms. McCabe can also be reached via electronic mail at

mccabe.sarah@epa.gov.

SUPPLEMENTARY INFORMATION:

I. Background

On November 13, 2009 (74 FR 58688), the EPA designated the Philadelphia area as nonattainment for the 2006 24-hour PM

2.5

NAAQS.

1

See

74 FR 58775 (November 13, 2009) and 40 Code of Federal Regulations (CFR) 81.308. New Castle County, Delaware was included in the Philadelphia nonattainment area.

1

On October 17, 2006 (71 FR 61144), the EPA lowered the level of the 24-hour PM

2.5

NAAQS to 35 µg/m

3

based on a 3-year average of the annual 98th percentile values of 24-hour concentrations.

On December 12, 2012, the State of Delaware submitted to the EPA a redesignation request and maintenance plan for the New Castle County portion of the Philadelphia Area. The EPA redesignated the New Castle County portion of the Philadelphia Area from nonattainment to attainment for the 2006 24-hour PM

2.5

NAAQS and approved the maintenance plan for the first 10-year maintenance period into the Delaware SIP.

2

2

See

79 FR 45350 (August 5, 2014).

On April 15, 2024, DNREC, on behalf of the State of Delaware, submitted an LMP to fulfill the second 10-year planning requirement of CAA section 175A(b) to ensure 2006 24-hour PM

2.5

NAAQS compliance for the New Castle County portion of the Philadelphia Area through 2034. On November 20, 2025 (90 FR 52290), the EPA published a notice of proposed rulemaking (NPRM) for the State of Delaware, proposing approval of the LMP because the State made a showing, consistent with the EPA's Guidance on the Limited Maintenance Plan Option for Moderate PM

2.5

Nonattainment Areas and PM

2.5

Maintenance Areas (PM

2.5

LMP Guidance), that the area's PM

2.5

concentrations are well below the 2006 24-hour PM

2.5

NAAQS, have been historically stable, and that it has met all other maintenance plan requirements.

3

3

The guidance document titled “Guidance on the Limited Maintenance Plan Option for Moderate PM

2.5

Nonattainment Areas and PM

2.5

Maintenance Areas” can be found at

nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P1015UL4.pdf.

A copy of the guidance is in the docket for the rulemaking.

Additionally, in the November 20, 2025 action, the EPA initiated the adequacy process and proposed that the LMP demonstrated that it is unreasonable to expect that this area would experience enough motor vehicle emissions growth for a violation of the NAAQS to occur, per the EPA's transportation conformity regulations.

4

The adequacy process is set forth in the transportation conformity regulation at 40 CFR 93.118(f).

4

See 40 CFR 93.109(e).

The EPA is approving the plan because it meets all applicable requirements under CAA sections 110 and 175A. As a general matter, the LMP relies on the same control measures and contingency provisions to maintain the 2006 24-hour PM

2.5

NAAQS during the second 10-year portion of the maintenance period as the maintenance

plan submitted by DNREC for the first 10-year period.

Further explanation of the CAA requirements, a detailed analysis of the revision, and the EPA's reasons for proposing approval were provided in the NPRM (90 FR 52290). The November 20, 2025 NPRM also includes additional detail about the adequacy process and the EPA's assessment of the adequacy of Delaware's submission. A summary of the comments received, as well as the EPA's responses, are in section II of this preamble.

II. The EPA's Response to Comments Received

The EPA's November 20, 2025 NPRM (90 FR 52290) opened a public comment period, which closed on December 22, 2025. The EPA received comments from one commenter. All comments received have been placed in the docket for this action.

A summary of the relevant comments and the EPA's response thereto are listed below.

Comment 1:

The commenter asks the EPA to include the PM

2.5

LMP Guidance in the docket and explain how CAA section 175A is satisfied under the guidance. Additionally, the commenter requests that if the guidance is being used as a binding norm, the EPA should consider a notice-and-comment rulemaking as treating guidance as binding could bypass the Administrative Procedure Act (APA) requirements.

Response 1:

The EPA disagrees with this comment. The PM

2.5

LMP Guidance was included in the docket at the time of NPRM publication. Additionally, section 175A of the CAA defines the general framework of a maintenance plan. The LMP is a tool that allows certain nonattainment and maintenance areas to provide for maintenance under CAA section 175A based on an analysis of current and historical air quality data, rather than modeling or emissions projections. Moderate PM

2.5

nonattainment areas or existing PM

2.5

maintenance areas meeting the criteria in the PM

2.5

LMP Guidance may demonstrate maintenance for purposes of CAA section 175A using the method described in the PM

2.5

LMP Guidance and the NPRM for this rule.

Importantly, the PM

2.5

LMP Guidance as binding nor bypassing APA requirements. To the extent that it builds upon previous EPA guidance, such guidance does not impose legally binding requirements either.

Comment 2:

The commenter urges the EPA to ensure transparency and public accessibility when incorporating by reference. They stress compliance with 1 CFR part 51 by identifying the LMP documents by title, date, and version, and making them freely available to the public.

Response 2:

The EPA disagrees with the commenter's assertion that it did not comply with 1 CFR part 51. In accordance with the requirements of 1 CFR 51.5, all the requested documentation was provided at the time of proposal.

See

docket ID EPA-R03-OAR-2025-0205. Through this rule, the EPA is amending 40 CFR 52.420(e) by adding the entry “2006 24-hour PM

2.5

Standard Second Maintenance Plan for the Delaware Portion of the Philadelphia-Wilmington, PA-NJ-DE Area” to the table. It simply adds the LMP to 40 CFR 52.420(e),

EPA-approved non-regulatory and quasi-regulatory material.

The EPA has made, and will continue to make, these materials generally available through

www.regulations.gov

and at the EPA Region III Office (please contact the person identified in the

FOR FURTHER INFORMATION CONTACT

section of the preamble for more information).

Comment 3:

The commenter claimed that the EPA did not comply with multiple statutory requirements and Executive Order 12866. First, the commenter claims that the EPA did not comply with the Paperwork Reduction Act (PRA) as the Limited Maintenance Plan commits the State to requirements for periodic verification of continued attainment, reporting of ambient monitoring data, and the submission of emissions inventories. The commenter states that once approved into the SIP, these are federally enforceable duties to submit information to a Federal agency. The commenter argues that as a result, the EPA must explain why this action is exempt from the PRA or identify an approved Information Collection Request or take steps to obtain one. Second, the commenter claims that the EPA did not comply with the Unfunded Mandates Reform Act (UMRA), as the EPA's conclusory statement that the action does not impose Federal mandates is inadequate. The commenter indicates that the LMP and its contingency measures can impose federally mandated duties on the state, which by extension may lead to impacts on local jurisdictions. The commenter references potential costs associated with implementing contingency measures. Third, the commenter claims that the EPA did not comply with the Regulatory Flexibility Act/Small Business Regulatory Enforcement Fairness Act (RFA/SBREFA), as it does not explain why the LMP does not have a significant impact on a substantial number of small entities. Specifically, the commenter indicates that the LMP's contingency measures, once federally approved, may trigger the adoption and implementation of measures by small governmental jurisdictions. It states that the EPA should either provide an Initial Regulatory Flexibility Analysis or provide a reasoned, evidence-based certification. Lastly, the commenter claims that the EPA did not comply with Executive Order (E.O.) 12866 as it appears to treat the action as not significant, and thus not subject to OMB review, but due to the multi-state metropolitan area covered by the LMP, OMB review would aid interagency coordination and transparency.

Response 3:

The EPA disagrees with the commenter with respect to its compliance with each statute and E.O. 12866. Regarding the PRA, it does not apply to this action. The PRA generally provides that every Federal agency must obtain OMB approval before using identical questions to collect information from 10 or more persons.

See

44 United States Code (U.S.C.) 3502(3); 3507. The EPA is not conducting nor sponsoring the collection of information from 10 or more persons. The EPA is merely approving Delaware's Limited Maintenance Plan to ensure continued compliance with the 2006 24-hour PM

2.5

NAAQS. It is approving State choices as meeting the Clean Air Act. The approval of the LMP does not impose any additional regulatory requirements, beyond those required by State law. The EPA has complied with the PRA by certifying in the rule that the PRA does not apply because this action does not involve an information collection burden as defined by the Act.

5

5

See 44 U.S.C. 3502(2).

With regard to the UMRA, the EPA disagrees with the commenter. As stated above, it merely approves Delaware's LMP and thus Delaware's choices as meeting Clean Air Act requirements. This action does not impose any additional regulatory requirements on sources beyond those required by State law. In the context of the UMRA, it therefore does not impose any Federal mandate on Delaware as that term is defined in the Act. 2 U.S.C. 1555 (“Notwithstanding section 1502 of this title, for purposes of this subchapter [2 U.S.C. 1551

et seq.

] the term “Federal mandate” means any provision in statute or regulation or any Federal court ruling that imposes an enforceable duty upon State, local, or Tribal governments including a condition of Federal assistance or a duty arising from participation in a voluntary Federal

program.”). Accordingly, the EPA has complied with the UMRA by making its own determination that this rule will not result in expenditures of $100M or more in any one year by State, local, and Tribal governments, in the aggregate, or by the private sector, and therefore the Agency does not need to complete a statement under 2 U.S.C. 1532.

Specific to the RFA and SBREFA, the EPA disagrees with the commenter. These statutes are inapplicable to this rule because the EPA has certified that this rule will not have a significant economic impact on a substantial number of small entities. The regulatory analysis provisions of the RFA are only triggered by a threshold determination by the Agency that this rule will have a significant economic impact on a substantial number of small entities. The EPA has considered the approval of the LMP in the context of the RFA and SBREFA. As previously noted, this action merely approves Delaware's LMP and thus Delaware's choices as meeting Clean Air Act requirements. This action does not impose any additional regulatory requirements on sources beyond those required by State law. The EPA's approval of the LMP does not establish any new regulatory requirement for any entity. Accordingly, as the EPA has certified that this rule will not have a significant economic impact on a substantial number of small entities, sections 603 and 604 of the RFA do not apply to this rule. 5 U.S.C. 605(b).

Lastly, the EPA disagrees with the commenter's assertions regarding Executive Order 12866. The EPA has complied with Executive Order 12866 by determining that this rule is not a significant regulatory action. Again, the EPA is approving Delaware's LMP and as a result Delaware's choices as meeting Clean Air Act requirements. This action does not impose any additional regulatory requirements on sources beyond those required by State law. Accordingly, the EPA has determined that this rule is not a significant regulatory action as defined in E.O. 12866. The EPA did not consult with the Office of Information and Regulatory Affairs (OIRA) as it is not required for this action.

III. Final Action

In accordance with the CAA and for the reasons set forth in the NPRM, the EPA is finalizing approval of Delaware's second 10-year LMP for the New Castle County portion of the Philadelphia area for the 2006 24-hour PM

2.5

NAAQS. The EPA's review of the air quality data for the area indicates that it continues to show attainment well below the level of the 2006 PM

2.5

NAAQS and meet all the LMP qualifying criteria set forth in the PM

2.5

LMP Guidance, consistent with CAA section 175A. The EPA finds the 2006 24-hour PM

2.5

LMP for the New Castle County portion of the Philadelphia area to be sufficient to provide for maintenance of the 2006 24-hour PM

2.5

NAAQS in its respective area over the second 10-year maintenance period, through 2034, and thereby satisfy the requirements for such a plan under CAA section 175A(b). The EPA finds the LMP adequate for transportation conformity purposes because it demonstrates that it would be unreasonable to expect that the area would experience enough motor vehicle emissions growth for a PM

2.5

NAAQS violation to occur, as required by 40 CFR 93.109(e). The EPA is approving this second maintenance plan as a revision to the Delaware SIP.

IV. Statutory and Executive Order Reviews

Under the Clean Air Act, the Administrator is required to approve a SIP submission that complies with the provisions of the Clean Air Act and applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, the EPA's role is to approve State choices, provided that they meet the criteria of the Clean Air Act. Accordingly, this action merely approves State law as meeting Federal requirements and does not impose additional requirements beyond those imposed by State law. For that reason, this action:

• Is not a significant regulatory action subject to review by the Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993);

• Is not an Executive Order 14192 (90 FR 9065, February 6, 2025) regulatory action because this action is not significant under Executive Order 12866;

• Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501

et seq.

);

• Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601

et seq.

);

• Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);

• Does not have federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);

• Is not subject to Executive Order 13045 (62 FR 19885, April 23, 1997) because it approves a State program;

• Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001); and

• Is not subject to requirements of section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the Clean Air Act.

In addition, the SIP is not approved to apply on any Indian reservation land or in any other area where the EPA or an Indian Tribe has demonstrated that a Tribe has jurisdiction. In those areas of Indian country, the rule does not have Tribal implications and will not impose substantial direct costs on Tribal governments or preempt Tribal law as specified by Executive Order 13175 (65 FR 67249, November 9, 2000).

This action is subject to the Congressional Review Act, and the EPA will submit a rule report to each House of the Congress and to the Comptroller General of the United States. This action is not a “major rule” as defined by 5 U.S.C. 804(2).

Under section 307(b)(1) of the Clean Air Act, petitions for judicial review of this action must be filed in the United States Court of Appeals for the appropriate circuit by August 31, 2026. Filing a petition for reconsideration by the Administrator of this final rule does not affect the finality of this action 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 section 307(b)(2).)

List of Subjects in 40 CFR Part 52

Environmental protection, Air pollution control, Incorporation by reference, Intergovernmental relations, Particulate matter, Reporting and recordkeeping requirements.

Amy Van Blarcom-Lackey,

Regional Administrator, Region III.

For the reasons stated in the preamble, the EPA amends 40 CFR part 52 as follows:

PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

1. The authority citation for part 52 continues to read as follows:

Authority:

42 U.S.C. 7401

et seq.

Subpart I—Delaware

2. In § 52.420, the table in paragraph (e) is amended by adding an entry “2006 24-hour PM

2.5

Standard Second Maintenance Plan for the Delaware Portion of the Philadelphia-Wilmington, PA-NJ-DE Area” at the end of the table to read as follows:

§ 52.420

Identification of plan.

(e) * * *

Name of

non-regulatory

SIP revision

Applicable

geographic

area

State

submittal

date

EPA

approval

date

Additional

explanation

*         *         *         *         *         *         *

2006 24-hour PM

2.5

Standard Second Maintenance Plan for the Delaware Portion of the Philadelphia-Wilmington, PA-NJ-DE Area

New Castle County

04/15/24

07/02/26, 91 FR [INSERT

Federal Register

PAGE WHERE THE DOCUMENT BEGINS]

2nd maintenance plan (limited maintenance plan).

[FR Doc. 2026-13396 Filed 7-1-26; 8:45 am]

BILLING CODE 6560-50-P