SUPPLEMENTARY INFORMATION:

I. What is being proposed?

North Carolina submitted a SIP revision on October 1, 2024, seeking to remove its SIP-approved I/M program, which covers the following counties: Alamance, Buncombe, Cabarrus, Cumberland, Davidson, Durham, Forsyth, Franklin, Gaston, Guilford, Iredell, Johnston, Lincoln, Mecklenburg, New Hanover, Randolph, Rowan, Union, and Wake. The SIP-approved I/M program consists of the following rules under 15A NCAC 02D, Section .1000 Motor Vehicle Emission Control Standards: Rule .1001, Purpose; Rule .1002, Applicability; Rule .1003, Definitions; and Rule .1005, On-Board Diagnostic Standards. NCDAQ submitted this SIP revision in response to North Carolina Session Law (S.L.) 2023-134 (House Bill 259), which amended North Carolina General Statute (NCGS) section 143-215.107A(c).^[1]

Sections 182(b)(4) and 187(a)(4) of the CAA require the implementation of an I/M program in certain areas classified as Moderate nonattainment or higher for the ozone or carbon monoxide (CO) National Ambient Air Quality Standards (NAAQS). In addition to the counties that were required to implement I/M in North Carolina by the CAA, North Carolina opted to expand the I/M program to comply with a rule entitled “Finding of Significant Contribution and Rulemaking for Certain States in the Ozone Transport Assessment Group Region for Purposes of Reducing Regional Transport of Ozone” (also referred to as the NO_X SIP Call).^[2] The I/M program was expanded in 2002 to include 39 total counties, including those covered in this proposed action, to provide North Carolina with emissions credits to meet its NO_X SIP Call obligations. See67 FR 66056 (October 30, 2002). The NO_X SIP Call, issued by EPA in 1998, required some states, including North Carolina, to meet statewide NO_X emission requirements during the ozone season (May 1 through September 30 control period) to reduce the amount of ground level ozone that is transported across the eastern United States. See84 FR 8422 (March 8, 2019). All counties in North Carolina are currently designated as attainment for all NAAQS.

As a part of the State's October 1, 2024, submittal, North Carolina included a CAA section 110(l) non-interference demonstration. Under section 110(l) of the CAA, EPA cannot approve a SIP revision if it would interfere with any applicable requirement concerning attainment and reasonable further progress (as defined by section 171 of the CAA), or any other applicable requirement of the CAA. Section III, below, provides EPA's analysis of the non-interference demonstration.

EPA is proposing to find that removal of North Carolina's I/M program from the SIP for the remaining 19 counties would not interfere with North Carolina's obligations under the NO_X SIP Call. This proposed finding is based on several federal rules and SIP-approved State provisions promulgated and implemented after EPA's 2002 approval of North Carolina's NO_X SIP Call submission. These federal rules and SIP provisions have created significant NO_X emission reductions in North Carolina such that the credits gained by the 19 counties' participation in the I/M program are no longer needed for North Carolina to meet its NO_X SIP Call Statewide NO_X emissions budget. North Carolina has provided an analysis which supports this proposed finding and is discussed in Sections II.B and III.A of this notice of proposed rulemaking (NPRM).

North Carolina's SIP revision also evaluates the impact that the removal of the I/M program would have on the ( printed page 25258) State's ability to attain and maintain the NAAQS. The SIP revision contains a technical demonstration with revised emissions calculations showing that removing the I/M program from the SIP would not interfere with attainment or maintenance of any NAAQS or any other applicable requirement of the CAA. As discussed more fully in Section III of this NPRM, EPA is proposing to find that North Carolina's emissions calculations demonstrate that removing the I/M program from the SIP would not interfere with the State's ability to attain or maintain any NAAQS.

II. Background

A. History of North Carolina's I/M Program

North Carolina's I/M program began in 1982 in Mecklenburg County utilizing a “tailpipe” emissions test. In 1984, Wake County was first added to the program for CO NAAQS violations. From 1986 through 1991 the program expanded to include Cabarrus, Davidson, Durham, Forsyth, Gaston, Guilford, and Union Counties, to address violations of the ozone and/or CO NAAQS. The I/M program was also implemented in Orange County although it was not designated as nonattainment for the ozone or CO NAAQS.

In 1999, the North Carolina General Assembly passed legislation (Session law 1999-328) to expand the coverage area for the I/M program to gain additional emission reduction credits for its NO_X SIP call obligations as well as to achieve the 1997 8-hour ozone NAAQS in the State. This legislation expanded the I/M program to add 38 counties between July 1, 2003, and July 1, 2006, for a total of 48 counties.^[3] The I/M program in the expanded coverage area used on-board diagnostic (OBD) system checks rather than tailpipe testing.

On August 7, 2002, North Carolina submitted a SIP revision to amend the I/M regulations included in the SIP at that time to, among other things, expand the counties subject to the I/M program as discussed above, and to require OBD testing in the subject counties for all light duty gasoline vehicles with a model year (MY) of 1996 and newer. Additionally, the SIP revision proposed to terminate the tailpipe testing program on January 1, 2006, for the nine counties subject to continued tailpipe testing with a MY 1995 and older vehicles. EPA approved this SIP revision on October 30, 2002. See67 FR 66056.

On January 31, 2008, May 24, 2010, October 11, 2013, and February 11, 2014, North Carolina submitted SIP revisions to change the I/M program to exempt the three newest MY vehicles with less than 70,000 miles among other changes. EPA approved these SIP revisions on February 5, 2015. See80 FR 6455.

On November 17, 2017, North Carolina submitted a SIP revision to remove 26 counties from the I/M program. EPA approved this SIP revision on September 25, 2018. See83 FR 48383.

On July 25, 2018, North Carolina submitted a SIP revision to revise the MY coverage for the then remaining 22 counties subject to the I/M program. EPA approved this SIP revision on September 11, 2019. See84 FR 47889.

On December 14, 2020, North Carolina submitted a SIP revision to remove three additional counties from the I/M program (Lee, Onslow, and Rockingham Counties). EPA approved this SIP revision on August 11, 2022. See87 FR 49524.

The remaining 19 counties in North Carolina's SIP-approved I/M program are Alamance, Buncombe, Cabarrus, Cumberland, Davidson, Durham, Franklin, Forsyth, Gaston, Guilford, Johnston, Iredell, Lincoln, Mecklenburg, New Hanover, Randolph, Rowan, Union, and Wake.

B. NO_X SIP Call

On August 7, 2002, North Carolina submitted a SIP revision to EPA as a component of its response to the NO_X SIP Call requirements. The NO_X SIP Call required some states to meet statewide NO_X emission requirements during the ozone season to reduce the amount of ground level ozone transported across the eastern United States. See84 FR 8422 (March 8, 2019). As noted above, North Carolina's SIP revision expanded the I/M program from 10 counties to 48, pursuant to North Carolina Session Law 1999-328, Section 3.1(d), and incorporated the OBD test procedure.

The addition of 38 counties to the I/M program pursuant to Section 3.1(d) of the 1999 Session Law and the new OBD testing procedure were included in the SIP to support the establishment of emission credits for North Carolina's NO_X budget and trading program. See67 FR 66056 (October 30, 2002). EPA approved the I/M rule revision and North Carolina's use of the I/M program credits for the NO_X SIP Call budget and trading program. See67 FR 66056 (October 30, 2002).

After the NO_X SIP Call, several federal rules, as well as North Carolina SIP provisions, have created significant NO_X emission reductions in North Carolina, including ozone season reductions. Consequently, the State asserts that any emissions reduction credits derived from the 19 counties' participation in the expanded I/M program are no longer needed for North Carolina to meet its Statewide NO_X emissions budget obligations under the NO_X SIP Call.

Other large reductions in NO_X emissions over time have occurred from federal rules such as the Tier 2 vehicle and fuel standards; ^[4] nonroad spark ignition engines and recreational engine standards; heavy-duty gasoline and diesel highway vehicle standards; ^[5] and large nonroad diesel engine standards.^[6] These mobile source measures, coupled with fleet turnover ( i.e., the replacement over time of older vehicles that predate the standards with newer vehicles that meet the standards), have resulted in, and continue to result in, large reductions in NO_X emissions over time.

In 2002, North Carolina also enacted and subsequently implemented its Clean Smokestacks Act (CSA), which created system-wide annual emissions caps on actual emissions of NO_X and sulfur dioxide (SO₂) from coal-fired power plants within the State, the first of which became effective in 2007. The CSA required certain coal-fired power plants in North Carolina to significantly reduce annual NO_X emissions by 189,000 tons (or 77 percent) by 2009 (using a 1998 baseline year). This represented about a one-third reduction of the NO_X emissions from all sources in North Carolina. See76 FR 36468 (June 11, 2011). The CSA's requirement to meet annual emissions caps and disallow the purchase of NO_X credits to meet the caps led to a reduction of NO_X emissions beyond the requirements of the NO_X SIP Call even though the CSA did not limit emissions only during the ozone season. EPA approved the CSA emissions caps into North Carolina's SIP ( printed page 25259) on September 26, 2011. See76 FR 59250.

North Carolina also has other SIP-approved provisions that have helped significantly reduce NO_X emissions in North Carolina. Most of these rules are contained in 15A North Carolina Administrative Code (NCAC) Subchapter 02D, Section .1400, Nitrogen Oxides. These rules contain NO_X SIP Call requirements and work in conjunction with the CSA to reduce NO_X emissions in the State. Together, implementation of the federal rules discussed above and SIP-approved State provisions have created significant NO_X emissions reductions since North Carolina's NO_X SIP Call emissions budget was approved into the SIP in 2002. These federal rules and SIP-approved State provisions have significantly reduced ozone season NO_X emissions, from Electric Generating Units (EGUs) in particular, resulting in overall emissions levels well below the original NO_X SIP Call budget. North Carolina asserts in its October 1, 2024, SIP revision that the State can adequately implement the NO_X SIP Call with the modeled increases in NO_X emissions resulting from removal of the I/M program and that the resulting NO_X emissions do not approach the applicable NO_X budget in the State. See Section III.A of this NPRM for additional discussion.

C. I/M in the North Carolina Portion of the Charlotte-Rock Hill, NC-SC 2008 Maintenance Area

The North Carolina portion of the Charlotte-Rock Hill, NC-SC Area (bi-state Charlotte Area) for the 2008 Ozone NAAQS contains Cabarrus, Gaston, Iredell, Lincoln, Mecklenburg, Rowan, and Union Counties. The I/M program is currently identified as a permanent and enforceable measure in the maintenance plan for the North Carolina portion of the Charlotte-Rock Hill, NC-SC Area for the 2008 8-hour ozone NAAQS. On February 28, 2025, North Carolina submitted a separate SIP revision containing the second 10-year maintenance plan to maintain the 2008 8-hour ozone NAAQS in the bi-state Charlotte Area. In that submittal, North Carolina seeks to move the vehicle I/M program to the contingency measures section.^[7] EPA intends to finalize action on the second 10-year maintenance plan for the North Carolina portion of the 2008 8-Hour ozone maintenance area when it finalizes action on the I/M SIP revision.

III. EPA's Analysis of North Carolina's Submittal

A. North Carolina's NO_X SIP Call Non-Interference Analysis

North Carolina's October 1, 2024, SIP revision includes a non-interference demonstration to support the removal of the I/M program, as required by section 110(l) of the CAA. EPA evaluates section 110(l) non-interference demonstrations on a case-by-case basis considering the circumstances of each SIP revision. Removal of the I/M program would remove reliance on the I/M reduction credits gained from the 19 counties' participation in the I/M program in meeting the State's NO_X emissions budget. North Carolina has demonstrated that it no longer needs these reduction credits to meet its obligation under the NO_X SIP Call.

As noted above, the federal and SIP-approved provisions that have been implemented since the I/M program was initially added to the SIP have resulted in adequate emission reductions such that the State remains far below the NO_X SIP Call budget. Specifically, Table 1 compares the EGU NO_X SIP Call budget to actual emissions in 2007, 2021, 2022, and 2023.

Further, the State provided mobile source modeling results showing that NO_X emissions will remain below the NO_X SIP Call budgets after removal of the I/M program from the remaining 19 counties. Specifically, NCDAQ utilized EPA's MOVES4.0.1 to model mobile source emissions increases. Table 2 shows the impact of the estimated ozone season NO_X emissions changes due to removal of the I/M program. EGU emissions in 2023 were 11,957 tons, which is 19,494 tons below the NO_X SIP Call budget for EGUs. The proposed removal of the I/M program would increase NO_X mobile emissions by 1,190 tons across all 48 counties, collectively. NCDAQ estimates an increase of 240 tons of NO_X in removing I/M from the 19 counties covered by the SIP-approved I/M program. As noted above, EPA previously approved removal of the other counties from the SIP-approved program and revised MY coverage for certain counties. Including the 2023 NO_X EGU emissions of 11,957 tons, the removal of the remaining 19 counties in the I/M program would increase NO_X emissions by 240 tons per ozone season. This would still leave a margin of 18,304 tons of NO_X between the projected emissions and the NO_X budget.

Therefore, EPA is proposing to find that removing the I/M program from the SIP would not interfere with the State's obligations under the NO_X SIP Call to meet its Statewide NO_X emissions budget. After the NO_X SIP Call, the promulgation and implementation of several federal rules and SIP-approved State provisions, particularly those impacting EGUs, have created significant NO_X emissions reductions in the State that are more than sufficient to meet its Statewide NO_X emissions budget even with the projected increase in NO_X emissions from the removal of the I/M program from the SIP.

B. North Carolina's NAAQS Non-Interference Analysis

North Carolina's non-interference demonstration includes an analysis of how the removal of the I/M program will affect each relevant NAAQS. The degree of analysis focused on any particular NAAQS in a non-interference demonstration varies depending on the nature of the emissions associated with the proposed SIP revision.

There are six NAAQS established to protect human health and the environment. These NAAQS are CO, lead (Pb), nitrogen dioxide (NO₂), ozone, particulate matter (PM)—including PM_2.5 (fine PM) and PM₁₀ (coarse PM), and SO₂ . This demonstration addresses all NAAQS with a focus on ozone (through its precursors NO_X and volatile organic compounds (VOCs)) and CO, the criteria pollutants targeted by I/M programs. The demonstration also focuses on PM_2.5 as VOCs and NO_X emissions are precursors that react in the atmosphere to form secondary fine PM. I/M programs are not designed to address Pb and SO₂  ^[8] emissions, and NO₂ is captured generally through the same measures that target NO_X impacts. Therefore, this section focuses on NO₂, ozone, CO, and PM_2.5. As previously mentioned, North Carolina is designated as attainment for all NAAQS.

EPA reviews the ozone monitoring network annually that North Carolina, Mecklenburg County Air Quality (MCAQ), Forsyth County Office of Environmental Assistance and Protection (FCEAP), and Asheville-Buncombe Air Quality Agency (ABAQA) operate and maintain in accordance with 40 CFR part 58. North Carolina and the local agencies submit an annual ambient air monitoring network plan as required by 40 CFR 58.10. EPA reviews the network plan to ensure that it meets the air monitoring network design requirements in 40 CFR part 58 and approves the plan if it meets the minimum requirements. The network plan includes the ozone monitoring network and the monitoring networks for PM, including PM₁₀ and PM_2.5, NO₂, SO₂, CO, and Pb. The annual network plans developed by NCDAQ, MCAQ, FCEAP, and ABAQA are posted for public inspection and comment for at least 30 days prior to submission to EPA, as required by 40 CFR 58.10(a)(1). North Carolina submits a combined network plan for the State and the local agencies. On October 29, 2025, EPA submitted a letter to North Carolina stating that the air monitoring network plan meets the requirements of 40 CFR part 58.^[9]

i. Non-Interference Analysis for the Ozone NAAQS

EPA promulgated a revised 8-hour primary and secondary ozone standard of 0.080 parts per million (ppm) on July 18, 1997. Subsequently, on March 12, 2008, EPA published a final rule revising both the primary and secondary NAAQS for ozone to a level of 0.075 ppm. See73 FR 16435 (March 27, 2008). On October 26, 2015, EPA published a final rule lowering the level of the 8-hour primary and secondary ozone NAAQS to 0.070 ppm. See80 FR 65292. The 2015 ozone NAAQS retains the same general form and averaging time as the 1997 ozone NAAQS and 2008 ozone NAAQS but is set at a lower level.

Under EPA's regulations at 40 CFR 50.19 and 40 CFR part 50, Appendix U, the 2015 8-hour ozone NAAQS is attained when the 3-year average of the annual fourth highest daily maximum 8-hour average ambient ozone concentration is less than or equal to 0.070 ppm. In 2017, the entirety of North Carolina (including all the 19 counties covered by this proposed rule) was designated attainment/unclassifiable for the 2015 ozone NAAQS. See82 FR 54232 (November 16, 2017).

Table 3 below shows the 2014-2016 through 2023-2025 ozone design values for all ozone monitors in the 19 counties covered by this proposed rule, demonstrating that these counties have maintained compliance with all of the 8-hour ozone NAAQS mentioned above during this time period.

The Charlotte-Rock Hill, NC-SC Areas were designated nonattainment for both the 1997 and 2008 8-hour ozone NAAQS. See69 FR 23858 and 77 FR 30088. The North Carolina portion of the 1997 Charlotte Area was redesignated to attainment and had its first 10-year maintenance plan approved for the 1997 8-hour ozone NAAQS in a December 2, 2013, final rule. See78 FR 72036. The North Carolina portion of this area had its second 10-year maintenance plan approved on January 13, 2023, and the maintenance period ends in 2034. See88 FR 2245. The design values used to assess compliance with the 8-hour ozone NAAQS are calculated according to the applicable procedures in 40 CFR part 50. Table 4 below shows the ozone design values for the 1997 8-hour ozone Charlotte Area, which encompasses the 2008 8-hour ozone Charlotte Area.

The North Carolina portion of the 2008 8-hour ozone NAAQS Charlotte Area was redesignated to attainment and had its first 10-year maintenance plan approved for the 2008 8-hour ozone NAAQS in a July 28, 2015, final rule. See80 FR 44873. North Carolina submitted its second 10-year maintenance plan for its portion of this area on February 28, 2025. As mentioned above, EPA intends to finalize action on the second 10-year maintenance plan for the North Carolina portion of this area when it finalizes action on the I/M SIP revision. Design values used to assess compliance with the 2008 8-hour ozone NAAQS are calculated according to the applicable procedures in 40 CFR part 50. See Table 4 above.

In 2017, the entire state of North Carolina was designated as “Attainment/Unclassifiable” for the 2015 ozone NAAQS based on the ozone season design values from 2014-2016. See82 FR 54232. The Garinger High School and University Meadows monitors are at 0.069 ppm for the most recent certified design value (2022-2024) and 0.068 ppm for the preliminary design values for 2023-2025. The 2026 critical 4th maximum daily maximum 8-hour ozone concentration for the Charlotte-Concord-Gastonia, NC-SC Metropolitan Statistical Area ( i.e., Charlotte MSA) is 0.079 ppm, based on the 2024 and 2025 monitored 4th maximum 8-hour values of 0.068 ppm and 0.063 ppm, respectively. Even with the emission increases projected from the removal of I/M, EPA believes that it is unlikely that the Charlotte MSA's 4th maximum 8-hour value will exceed 0.079 ppm in 2026 given the emissions analysis below, the fact that the Charlotte MSA monitors have not recorded a 4th maximum above 0.079 ppm in the past 13 years ( i.e., since 206), and the improvement in ozone air quality across the Southeast during this time period. As a result, EPA is proposing to determine that North Carolina has demonstrated that the removal of the I/M program will not interfere with attainment of the 2015 ozone NAAQS.

In North Carolina's submittal, the State showed that NO_X and VOC emissions would decrease over time in comparison to the 2014 base year emissions.^[10] The 2014 base year is an appropriate year for comparison because it is one of the three years ( i.e., 2014, 2015, and 2016) that was used to base the attainment/unclassifiable designations in North Carolina for the 2015 8-hour ozone NAAQS. As older vehicles are replaced with newer vehicles that emit less pollutants, NCDAQ estimated a decline of 53 percent in NO_X emissions in the Charlotte Area counties from 2025 to ( printed page 25262) 2035. Table 5 below shows the projected increase in NO_X and VOC emissions in 2025 associated with the removal of the I/M program and compares 2014 base year emissions for the counties in the Charlotte MSA.

Tables 6 and 7 below show the NO_X and VOC emissions changes from the proposed removal of the I/M program in the 19 counties covered by the SIP-approved I/M program. This change in I/M implementation was modeled with EPA's MOVES4.0.1 mobile emissions model. The only changes to emissions occurred in the onroad sector. These tables consider anthropogenic emissions only, meaning biogenic emissions are excluded from the analysis.

Tables 5 and 6 show that the NO_X emissions increase across the Charlotte MSA would be 0.62 tpd, representing a 1.0 percent increase in 2025 total area emissions. EPA is proposing that it is not reasonable to conclude that an increase of 0.62 tpd would cause the Charlotte Area MSA, whose critical value in 2026 is 0.079 ppm, to violate the 2015 8-hour ozone NAAQS—the most stringent 8-hour ozone NAAQS.

( printed page 25263)

Tables 5 and 7 show the VOC emissions increase across the Charlotte Area MSA would be 0.95 tpd, representing a 0.83 percent increase in total area emissions.^[11] EPA is proposing that it is not reasonable to conclude that an increase of 0.95 tpd would cause the Charlotte Area MSA, whose critical value in 2026 is 0.079 ppm, to violate the 2015 8-hour ozone NAAQS—the most stringent of the 8-hour ozone NAAQS. As mentioned above, even with the emission increases projected from the removal of I/M, EPA believes that it is unlikely that the Charlotte MSA's 4th maximum 8-hour value will exceed 0.079 ppm in 2026 given the emissions analysis below, the fact that the Charlotte MSA monitors have not recorded a 4th maximum above 0.079 ppm in the past 13 years ( i.e., since 2012), and the improvement in ozone air quality across the Southeast during this time period.

Regarding maintenance of the 2008 8-hour ozone Charlotte Area, Table 8  ¹² shows that the 2025 projected emissions without I/M are 54 percent below 2014 baseline NO_X emissions and 7.8 percent below 2014 baseline VOC emissions. Thus, the Charlotte Area is projected to maintain the NAAQS even with removal of the I/M program. As mentioned above, EPA intends to finalize action on the second 10-year maintenance plan for the North Carolina portion of this area when it finalizes action on the I/M SIP revision.

( printed page 25264)

As mentioned above, the entire state of North Carolina was designated as attainment/unclassifiable for the 2015 8-hour ozone NAAQS, so there is no analogous table to Table 8 for the 2015 8-hour ozone NAAQS; however, EPA believes it is reasonable to conclude that a 54 percent reduction in NO_X emissions and a 7.8 percent reduction in VOC emissions from the 2014 baseline emissions is still consistent with attainment of the 2015 8-hour ozone NAAQS. 2014 was one of the three years used to calculate the design value that supported the attainment/unclassifiable designation for the 2015 8-hour ozone NAAQS in North Carolina.

ii. Non-Interference Analysis for the Fine Particulate Matter (PM_2.5) NAAQS

Over the years, EPA has reviewed and revised the PM_2.5 NAAQS several times. On July 18, 1997, EPA established an annual PM_2.5 NAAQS of 15.0 micrograms per cubic meter (μg/m³ ), based on a 3-year average of annual mean PM_2.5 concentrations, and a 24-hour PM_2.5 NAAQS of 65 μg/m³ , based on a 3-year average of the 98th percentile of 24-hour concentrations. See62 FR 36852. On September 21, 2006, EPA retained the 1997 annual PM_2.5 NAAQS of 15.0 μg/m³ but revised the 24-hour PM_2.5 NAAQS to 35 μg/m³ , based again on a 3-year average of the 98th percentile of 24-hour concentrations. See71 FR 61144. On December 14, 2012, EPA retained the 2006 24-hour PM_2.5 NAAQS of 35 μg/m³ but revised the annual primary PM_2.5 NAAQS to 12.0 μg/m³ , based again on a 3-year average of annual mean PM_2.5 concentrations. See78 FR 3086. On March 6, 2024, EPA revised the annual primary PM_2.5 NAAQS to 9.0 μg/m³ , based again on a 3-year average of annual mean PM_2.5 concentrations. See89 FR 16202.

EPA promulgated designations for the 1997 Annual PM_2.5 NAAQS on January 5, 2005. See70 FR 944. The Greensboro-Winston Salem-High Point, NC Area, which contains Davidson and Guilford County, and the Hickory-Morganton-Lenoir, NC Area, which contains Catawba County, were designated as nonattainment on that date. On November 18, 2011, EPA redesignated the Greensboro-Winston Salem-High Point, NC Area and the Hickory-Morganton-Lenoir Area to attainment. See76 FR 71455 and 76 FR 71452. On November 13, 2009, and on January 15, 2015, EPA published notices determining that the entire state of North Carolina was unclassifiable/attainment for the 2006 24-hour PM_2.5 NAAQS and the 2012 annual PM_2.5 NAAQS, respectively. See74 FR 58688 and 80 FR 2206, respectively.

As stated earlier, in 2024 the annual primary PM_2.5 NAAQS was revised to 9.0 μg/m^[3] , based again on a 3-year average of annual mean PM_2.5 concentrations. Currently, all monitors in North Carolina are attaining the 2024 annual PM_2.5 NAAQS.^[13 14]

North Carolina's October 1, 2024, SIP revision concludes that the removal of the I/M program would not interfere with attainment or maintenance of the PM_2.5 NAAQS. As noted above in the “Totals” row from Tables 6 and 7, the modeled increase in precursor emissions of NO_X and VOCs is projected to be 1.66 tpd (1.0 percent) and 2.61 tpd (0.8 percent), respectively, across all 19 covered counties. For these reasons, EPA proposes to find that removal of the I/M program would not interfere with maintenance of the PM_2.5 NAAQS.

iii. Non-Interference Analysis for the 2010 NO₂ NAAQS

The 2010 NO₂ 1-hour standard is set at 100 ppb, based on the 3-year average of the 98th percentile of the yearly distribution of 1-hour daily maximum concentrations. The 1971 annual NO₂ standard of 53 ppb is based on the annual mean concentration. On February 17, 2012, EPA designated all counties in North Carolina as unclassifiable/attainment for the 2010 NO₂ NAAQS. See77 FR 9532.

Based on the technical analysis in North Carolina's October 1, 2024, SIP revision, the projected increase in total anthropogenic NO_X emissions (of which NO₂ is a component) associated with the removal of the I/M program ranges from a 0.02 tpd increase in total NO_X emissions (1.1 percent) for Franklin County to a 0.31 tpd increase in total NO_X emissions (1.1 percent) for Mecklenburg County in 2025. The DVs ^[15] from all NO₂ monitors in the State are attaining the 2010 1-hour NO₂ standard and the 1971 annual NO₂ standard. The highest-reading monitor in the State, the Equipment Drive monitor in Mecklenburg County (AQS ID: 37-119-0050), has a DV of 13 ppb for the annual NAAQS. The form of the annual NAAQS is a single year arithmetic mean. The form of the 2010 1-hour NAAQS requires three complete years of data. The Equipment Drive monitor does not yet have a complete three-year DV for the 1-hour NAAQS because it began operation in January 2024. The highest valid DV for the 1-hour NO₂ NAAQS in the State is the Remount Road Monitor (37-119-0045) at 36 ppb.

Given the margin between the NAAQS and the DVs for the annual and 1-hour NAAQS and the size of the projected increases in NO_X emissions due to the removal of I/M, EPA proposes to find that removal of the I/M program would not interfere with maintenance of the NO₂ NAAQS.

iv. Non-Interference Analysis for the CO NAAQS

EPA promulgated the CO NAAQS in 1971 and has retained the primary standard since its last review of the standard in 2011. The primary NAAQS for CO include: (1) an 8-hour standard ( printed page 25265) of 9.0 ppm, measured using the annual second highest 8-hour concentration for two consecutive years as the design value; and (2) a 1-hour average of 35 ppm, using the second highest 1-hour average within a given year. In 1995, Mecklenburg, Durham, and Wake County were redesignated from nonattainment to unclassifiable/attainment, and Forsyth County was redesignated to unclassifiable/attainment in 1994. See59 FR 48399 (September 21, 1994) and 60 FR 39258 (August 2, 1995).

North Carolina inventoried the emissions of CO from all anthropogenic sources for 2025, with and without the I/M program from the remaining 19 counties, showing an overall 6.4 percent projected increase in CO emissions. See Table 9 below. The highest 2023-2024 CO DVs ^[16] in the Charlotte (Mecklenburg County) metropolitan area are 1.6 ppm for the 8-hour CO DV and 2.0 ppm for the 1-hour DV at the Remount Road site (AQS ID: 37-119-0045). The highest 2022-2024 CO DVs in the Raleigh (Wake County) metropolitan area are 1.3 ppm for the 8-hour CO design value and 1.7 ppm for the 1-hour design value at the Millbrook School site (AQS ID: 37-183-0014). Given the margin between the NAAQS and the DVs for the 8-hour and 1-hour CO NAAQS and the size of the CO increases, EPA proposes to find that removal of the I/M program would not interfere with maintenance of the CO NAAQS.

IV. Incorporation by Reference

In this document, EPA is proposing to include in a final EPA rule amended regulatory text that includes incorporation by reference. EPA is proposing to remove Rules 15A NCAC 02D.1001, Purpose; Rule .1002, Applicability; Rule .1003, Definitions; and Rule .1005, On-Board Diagnostic Standards from the North Carolina SIP, which were incorporated by reference in accordance with the requirements of 1 CFR part 51, as discussed in Sections I through III of this preamble. EPA has made and will continue to make the SIP generally available at the EPA Region 4 Office (please contact the person identified in the For Further Information Contact section of this preamble for more information).

V. Proposed Action

EPA is proposing to find that removal of the I/M program from the North Carolina SIP would not interfere with any applicable requirement concerning attainment and RFP or any other applicable requirement of the CAA. Consequently, EPA is proposing to approve North Carolina's October 1, 2024, SIP revision and remove the I/M program from North Carolina's SIP. ( printed page 25266)

VI. Statutory and Executive Order Reviews

Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the CAA and applicable Federal regulations. See42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to approve state choices, provided that they meet the criteria of the CAA. Accordingly, this proposed 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 proposed action:

• Is not a significant regulatory action subject to review by the Office of Management and Budget underExecutive Order 12866 (58 FR 51735, October 4, 1993);
• Is not anExecutive 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 inExecutive Order 13132 (64 FR 43255, August 10, 1999);
• Is not subject toExecutive Order 13045 (62 FR 19885, April 23, 1997) because it approves a state program;
• Is not a significant regulatory action subject toExecutive 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 CAA.

In addition, the SIP is not approved to apply on any Indian reservation land or in any other area where 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. See65 FR 67249, November 9, 2000.

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

91 FR 25257