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AGENCY:
Environmental Protection Agency (EPA).
ACTION:
Proposed rule.
SUMMARY:
The Environmental Protection Agency (EPA) is proposing to approve, under the Clean Air Act (CAA), the limited maintenance plan (LMP) for the 2006 PM2.5 national ambient air quality standard (NAAQS) for New Haven and Fairfield Counties, which comprise the Connecticut portion of the New York-N. New Jersey-Long Island (NY-NJ-CT) 2006 PM2.5 NAAQS maintenance area. This LMP was submitted on May 9, 2023, and supplemented on February 21, 2024, by the Connecticut Department of Energy and Environmental Protection (CT DEEP). The plan addresses the second 10-year maintenance period for particulate matter with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers, known as PM2.5 . EPA is proposing approval of Connecticut's LMP submission because it provides for the maintenance of the 2006 24-hour PM2.5 NAAQS through the end of the second 10-year portion of the maintenance period. In addition, EPA is initiating the process to find the Connecticut PM2.5 LMP adequate for transportation conformity purposes.
DATES:
Written comments must be received on or before October 28, 2024.
ADDRESSES:
Submit your comments, identified by Docket ID No. EPA-R01-OAR-2024-0117 at https://www.regulations.gov, or via email to martinelli.ayla@gmail.com. For comments submitted at Regulations.gov, follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov. For either manner of submission, the EPA may publish any comment received to its public docket. Do not submit electronically any information you consider to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission ( i.e., on the web, cloud, or other file sharing system). For additional submission methods, please contact the person identified in the FOR FURTHER INFORMATION CONTACT section. For the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets. Publicly available docket materials are available at https://www.regulations.gov or at the U.S. Environmental Protection Agency, EPA Region 1 Regional Office, Air and Radiation Division, 5 Post Office Square—Suite 100, Boston, MA. EPA requests that, if possible, you contact the contact listed in the FOR FURTHER INFORMATION CONTACT section to schedule your inspection. The Regional Office's official hours of business are Monday through Friday, 8:30 a.m. to 4:30 p.m., excluding legal holidays and facility closures due to COVID-19.
FOR FURTHER INFORMATION CONTACT:
Ayla Martinelli, Air Quality Branch, U.S. Environmental Protection Agency, EPA Region 1, 5 Post Office Square—Suite 100, (Mail code 5-MI), Boston, MA 02109-3912, tel. (617) 918-1057, email martinelli.ayla@epa.gov.
SUPPLEMENTARY INFORMATION:
Throughout this document whenever “we,” “us,” or “our” is used, we mean EPA.
Table of Contents
I. Background and Purpose
A. The PM2.5 National Ambient Air Quality Standards (NAAQS)
B. Regulatory Actions in New Haven and Fairfield Counties
II. The Limited Maintenance Plan Option
A. Demonstration of Maintenance Using the Limited Maintenance Plan Option
B. Transportation Conformity Under Limited Maintenance Plan Option
C. General Conformity Under Limited Maintenance Plan Option
III. EPA's Analysis of the State's Submittal
A. Demonstration of Qualification for the Limited Maintenance Plan Option
B. Attainment Inventory
C. Air Quality Monitoring Network
D. Verification of Continued Attainment
E. Contingency Provisions
IV. Proposed Action
V. Statutory and Executive Order Reviews
I. Background and Purpose
A. The PM 2.5 National Ambient Air Quality Standards (NAAQS)
EPA has established NAAQS for particulate matter with an aerodynamic diameter less than or equal to 2.5 micrometers, known as PM2.5, to protect human health and the environment. In 1997, EPA established the first PM2.5 standards based on significant scientific evidence and health studies demonstrating the serious health effects associated with exposure to PM2.5 . EPA set an annual standard of 15.0 micrograms per cubic meter (μg/m3 ) and a 24-hour (or daily) standard of 65 μg/m3 . In 2006, EPA strengthened the 24-hour PM2.5 NAAQS by revising it to 35 μg/m3 and retained the level of the annual PM2.5 standard at 15.0 μg/m3 . Subsequently, in 2012, EPA established an annual primary PM2.5 NAAQS at 12.0 μg/m3 and retained the 2006 24-hour PM2.5 NAAQS at 35 μg/m3 . In early 2024, EPA strengthened the level of the annual primary PM2.5 standard to 9.0 μg/m3 and retained the 2006 24-hour PM2.5 NAAQS at 35 μg/m3 .
B. Regulatory Actions in New Haven and Fairfield Counties
Hereafter, “New Haven-Fairfield” means the Connecticut portion of the NY-NJ-CT maintenance area which is comprised of New Haven and Fairfield Counties. EPA promulgated the designations for New Haven-Fairfield as a PM2.5 nonattainment area for the 1997 annual PM2.5 NAAQS on January 5, 2005 (70 FR 944) and the 2006 24-hour PM2.5 NAAQS (74 FR 58688) on November 13, 2009, due to measured violations of the standards. These designations became effective on April 5, 2005, and December 14, 2009, respectively. On June 22, 2012, CT DEEP submitted a request to EPA to redesignate the New Haven- Fairfield nonattainment area to attainment of both the 1997 annual and 2006 24-hour PM2.5 NAAQS. This submittal included a maintenance plan to provide for maintenance of the PM2.5 NAAQS in the area for 10 years. EPA redesignated New Haven-Fairfield to attainment for the 1997 and 2006 PM2.5 NAAQS on October 24, 2013 (78 FR 58467) and approved the associated maintenance plan into the Connecticut State Implementation Plan (SIP). The purpose of CT DEEP's May 9, 2023 (supplemented on February 21, 2024) LMP submission is to fulfill the second 10-year planning requirement of CAA section 175A(b), thus ensuring PM2.5 NAAQS compliance through the end of the maintenance period.
In the LMP submittal, CT DEEP indicates that it is seeking approval of the LMP for both the 2006 24-hour standard as well as the 1997 annual standard. However, as explained in the PM2.5 SIP Requirements Rule (81 FR 58009), a second 10-year maintenance plan for the revoked 1997 annual PM2.5 NAAQS is not required. Therefore, CT DEEP clarified via email that it incorrectly sought approval of the plan for the revoked 1997 annual standard and asked that EPA ignore the request for approval of the plan for this standard. The email, sent on July 7, 2023, can be found in the docket of this action. Thus, EPA will only proceed with proposing approval of the LMP for the 2006 24-hour PM2.5 NAAQS.
II. The Limited Maintenance Plan Option
A. Demonstration of Maintenance Using the Limited Maintenance Plan Option
Section 175A of the CAA sets forth the elements of a maintenance plan. Under section 175A, a state must submit a revision to the SIP that provides for maintenance of the applicable NAAQS for at least 10 years after an area is redesignated to attainment. Section 175A also requires that eight years into the first maintenance period, the state must submit a second maintenance plan demonstrating that the area will continue to attain for the following 10-year period.
EPA has published long-standing guidance for states on developing maintenance plans. The Calcagni memo provides that states may generally demonstrate maintenance by either performing air quality modeling to show that the future mix of sources and emission rates will not cause a violation of the NAAQS or by showing that future emissions of a pollutant and its precursors will not exceed the level of emissions during a year when the area was attaining the NAAQS ( i.e., attainment year inventory). EPA clarified in subsequent guidance memos that certain nonattainment areas could meet the CAA section 175A requirement to provide for maintenance by demonstrating that an area's design value is well below the NAAQS and that the historical stability of the area's air quality levels shows that the area is unlikely to violate the NAAQS in the future.
See Calcagni, John, Director, Air Quality Management Division, EPA Office of Air Quality Planning and Standards, “Procedures for Processing Requests to Redesignate Areas to Attainment,” September 4, 1992 (Calcagni memo). A copy of this memorandum can be found in the docket for this proposed rulemaking.
See “Limited Maintenance Plan Option for Nonclassifiable Ozone Nonattainment Areas” from Sally L. Shaver, Office of Air Quality Planning and Standards (OAQPS), dated November 16, 1994; “Limited Maintenance Plan Option for Nonclassifiable CO Nonattainment Areas” from Joseph Paisie, OAQPS, dated October 6, 1995; and “Limited Maintenance Plan Option for Moderate PM10 Nonattainment Areas” (PM10 LMP Guidance) from Lydia Wegman, OAQPS, dated August 9, 2001. Copies of these guidance memoranda can be found in the docket for this proposed rulemaking.
Most recently, in October 2022, EPA released guidance extending this streamlined option for demonstrating maintenance under CAA section 175A to certain PM2.5 areas, titled “Guidance on Limited Maintenance Plan Option for Moderate PM2.5 Nonattainment Areas and PM2.5 Maintenance Areas” (PM2.5 LMP Guidance). EPA refers to this streamlined demonstration of maintenance as an LMP. EPA has interpreted CAA section 175A as permitting this option because section 175A of the Act defines few specific content requirements for maintenance plans, and in EPA's experience implementing the various NAAQS, areas that qualify for an LMP and have approved LMPs have rarely, if ever, experienced subsequent violations of the NAAQS. As noted in the PM2.5 LMP Guidance, states seeking an LMP should still submit the other maintenance plan elements outlined in the Calcagni memo, including: an attainment emissions inventory, provisions for the continued operation of the ambient air quality monitoring network, verification of continued attainment, and a contingency plan in the event of a future violation of the NAAQS. Moreover, states seeking an LMP must still submit their section 175A maintenance plan as a revision to their SIP, with all attendant notice and comment procedures.
See the guidance document developed by the Office of Air Quality Planning and Standards, the Office of Transportation and Air Quality, and the Office of Air and Radiation titled “Guidance on the Limited Maintenance Plan Option for Moderate PM2.5 Nonattainment Areas and PM2.5 Maintenance Areas”. A copy of this guidance can be found in the docket for this proposed rulemaking.
The PM2.5 LMP Guidance, similar to the PM10 LMP Guidance, allows states to demonstrate that certain areas qualify for an LMP by showing that, based on their recent measured air quality, they are unlikely to violate the NAAQS in the future. Specifically, the PM2.5 LMP Guidance relies on the critical design value (CDV) concept. This guidance directs states to calculate a site-specific CDV for the monitoring site in an area with the highest design value, and also for all other active monitoring sites in the area with complete data. The PM2.5 LMP Guidance states that areas should show that the average design value (ADV) for each monitoring site in the area, i.e., the average of at least the most recent consecutive 5 years of PM2.5 design values, does not exceed the associated CDV for each site. If the ADV for each monitoring site in the area is below the CDV then the probability of a future exceedance, based on the area's historical air quality and variability, is less than 10 percent. The CDV calculation for a monitoring site involves the following parameters: (1) the level of the relevant NAAQS; (2) the co-efficient of variation of recent design values measured at that site; and (3) a statistical parameter corresponding to a 10 percent probability of exceedance, such that sites with historically high variability in design values result in a lower (or more stringent) CDV. The eligibility calculation equations for the CDV demonstration are shown in table 1.
EPA recommends that the ADV be calculated using at least five years of design values, each representing a three-year period, because this approach would rely on a more robust dataset. However, we acknowledge that an alternative interpretation may be acceptable, where these variables could be calculated using three years of design values, collectively representing five years of air quality data.
B. Transportation Conformity Under Limited Maintenance Plan Option
Transportation conformity is required by section 176(c) of the CAA. Under that provision, conformity to a SIP means that transportation activities will not cause or contribute to new air quality violations, worsen existing violations, delay timely attainment of the NAAQS or any required interim emission reductions or other milestones in any area. See CAA 176(c)(1)(A) and (B). EPA's transportation conformity rule at 40 CFR part 93 subpart A establishes the criteria and procedures to determine whether metropolitan transportation plans, transportation improvement programs, and federally supported highway and transit projects conform to the SIP. Transportation conformity applies for transportation-related criteria pollutants in nonattainment areas and redesignated attainment areas with a CAA section 175A maintenance plan ( i.e., maintenance areas).
While qualification for the LMP option does not exempt an area from the need to determine conformity, in an area with an adequate or approved LMP, conformity may be demonstrated for a transportation plan or a transportation improvement program without a regional emissions analysis for the relevant NAAQS and pollutant (40 CFR 93.109(e)). However, transportation plan and transportation improvement program conformity determinations that meet applicable requirements continue to be required in these areas (see table 1 in 40 CFR 93.109). The areas also remain subject to the other transportation conformity requirements of 40 CFR part 93, subpart A, including fulfilling project-level conformity analyses requirements and consultation requirements. In addition, an LMP must demonstrate that it is unreasonable to expect that the qualifying area would experience enough growth in on-road emissions during the maintenance period such that a violation of the relevant NAAQS would occur (40 CFR 93.109(e)). Furthermore, consistent with the PM2.5 LMP Guidance, if re-entrained road dust has been found to be significant for PM2.5 transportation conformity purposes under 40 CFR 93.102(b)(3), the plan should include an on-road PM2.5 emissions analysis consistent with the methodology provided in attachment B of the PM10 LMP Guidance. EPA discusses CT DEEP's submittal in section III.A of this notice.
Along with this proposed action, EPA is initiating an adequacy process for the New Haven and Fairfield LMP. See40 CFR 93.118(e)(4) and 93.118(f). Since LMPs do not include motor vehicle emissions budgets, EPA's adequacy review is to assess whether the demonstration required by 40 CFR 93.109(e) is met.
C. General Conformity Under Limited Maintenance Plan Option
The general conformity rule of November 30, 1993 (58 FR 63214) applies to nonattainment areas and redesignated attainment areas operating under maintenance plans ( i.e., maintenance areas). General conformity requires compliance to the purpose of a SIP, which means that federal activities not related to transportation plans, programs, and projects will not cause or contribute to any new violation of any standard in any area, increase the frequency or severity of any existing violation of any standard in any area or delay timely attainment of any standard or any required interim emission reductions or other milestones in any area (CAA section 176(c)(1)(A)and(1)(B)). As noted in the PM2.5 LMP Guidance, EPA's general conformity regulations do not distinguish between maintenance areas with an approved “full maintenance plan” and those with an approved LMP. Thus, maintenance areas with an approved LMP are subject to the same general conformity requirements under 40 CFR part 93 subpart B, as those covered by a “full maintenance plan.” Full compliance with the general conformity program is required within an LMP.
III. EPA's Analysis of the State's Submittal
A. Demonstration of Qualification for the Limited Maintenance Plan Option
EPA redesignated New Haven- Fairfield to attainment of the PM2.5 NAAQS on October 24, 2013 (78 FR 58467). Table 2 below shows the historical design values for each monitoring site within the maintenance area since it was redesignated in 2013. The 2006 24-hour PM2.5 NAAQS is attained when the 3-year average of the 98th percentile of 24-hour PM2.5 concentrations is equal to or less than 35 µg/m3 , and as shown in table 2, the area has been measuring air quality well below the 2006 PM2.5 NAAQS with an overall decrease in PM2.5 concentrations over time. These design values from the individual monitoring sites within the maintenance area demonstrate the stability of ambient PM2.5 concentrations over time.
Table 2—PM 2.5 Design Values in New Haven-Fairfield Since Redesignation to Attainment in µg/m
[2013-2023]
The 2020-2022 and 2021-2023 design values were not finalized until after CT DEEP submitted the PM2.5 LMP to EPA; they are included here to show the most recent air quality data.
Table 3—Results of Calculation of CDVs at New Haven-Fairfield Monitors for the 24-Hour PM 2.5 NAAQS
Table 3—2017 Emissions (Tons/Year) in New Haven-Fairfield
| Pollutant | Total emissions |
|---|---|
| PM 2.5 | 4,361 |
| Ammonia (NH 3 ) | 1,485 |
| Nitrogen oxides (NO X ) | 22,020 |
| Sulfur dioxide (SO 2 ) | 1,296 |
| Volatile organic compounds (VOCs) | 43,518 |