2023-06461. Air Plan Approval; Idaho: Inspection and Maintenance Program Removal

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency (EPA) proposes to approve revisions to the Idaho State Implementation Plan (SIP) submitted by the State of Idaho (Idaho or the State) on December 29, 2022. The proposed revision, applicable in the Boise-Northern Ada County Carbon Monoxide area (Northern Ada County CO area) in Idaho, removes the Inspection and Maintenance (I/M) program, which was previously approved into the SIP for use as a control measure in the State's plan to address motor vehicle emissions in the nonattainment area. The SIP submission includes a demonstration that the requested revision will not interfere with attainment or maintenance of any national ambient air quality standard (NAAQS) or with any other applicable requirement of the Clean Air Act (CAA or Act). The EPA evaluated whether this SIP revision would interfere with the requirements of the CAA and is proposing to determine that Idaho's December 29, 2022, SIP revision is consistent with the applicable portions of the CAA.

DATES:

Comments must be received on or before May 1, 2023.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA–R10–OAR–2023–0012, at https://www.regulations.gov. Follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov. The EPA may publish any comment received to its public docket. Do not electronically submit any information you consider to be Confidential Business Information (CBI) or other information the disclosure of which 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, 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.

FOR FURTHER INFORMATION CONTACT:

Claudia Vaupel, EPA Region 10 at (206) 553–6121, or [e-mail].

SUPPLEMENTARY INFORMATION:

Throughout this document, wherever “we,” “us,” or “our” is used, it means the EPA.

I. Background

Each state has a SIP containing the control measures and strategies used to attain and maintain the NAAQS established by the EPA for the six criteria pollutants (carbon monoxide (CO); nitrogen dioxide (NO₂); ozone (O₃); sulfur dioxide (SO₂); particulate matter, both (PM_2.5) and (PM₁₀); and lead (Pb)). The SIP contains such elements as air pollution control regulations, emission inventories, attainment demonstrations, and enforcement mechanisms. Section 110 of the CAA requires each state to periodically revise its SIP. As a result, the SIP is a living compilation of regulatory and non-regulatory elements that are updated to address Federal requirements and changing air quality issues in the state.

Idaho has implemented a mandatory motor vehicle I/M program as part of the Northern Ada County CO area SIP since the 1980s. ( See50 FR 23810, June 6, 1985). On March 3, 1978, the EPA designated the Northern Ada County CO area as nonattainment for the 1971 CO NAAQS (43 FR 8962). Under CAA section 107(d)(1)(C), the nonattainment designation for the Northern Ada County CO area was retained by operation of law following enactment of the Clean Air Act Amendments of 1990 (56 FR 56818, November 6, 1991).¹

On January 17, 2002, Idaho submitted a request to the EPA to redesignate the Northern Ada County CO area to attainment. In accordance with CAA section 175A(a), at the same time Idaho submitted the redesignation request, Idaho submitted a maintenance plan to maintain the CO NAAQS for 10 years after redesignation. The EPA redesignated the Northern Ada County CO area to attainment for the CO NAAQS on October 28, 2002, and approved Idaho's 10-year maintenance plan. ( See67 FR 65713). In accordance with CAA section 175A(b), Idaho submitted a second maintenance plan to maintain the CO NAAQS for another 10 years following the conclusion of the first 10-year maintenance period. On August 2, 2012, the EPA approved Idaho's maintenance plan to maintain the CO NAAQS for a second 10-year period in the Northern Ada County CO area ( See77 FR 45962). Accordingly, pursuant to CAA section 175A, the 20-year maintenance period for the Northern Ada County CO area ended on December 27, 2022. Although the CAA section 175A 20-year maintenance period has expired, all control measures in the maintenance plan remain in effect and must be complied with until the state submits, and the EPA approves, a SIP revision.^[2] However, the CAA section 175A(d) requirement for contingency measures to include all control measures contained in the SIP prior to redesignation does not preclude the removal of control measures once the second 10-year maintenance plan period has expired.^[3]

Table 1 of this preamble lists the local ordinances that were approved into the Idaho SIP as part of the Northern Ada County CO area maintenance plans to implement the I/M program. In the December 29, 2022, submission, Idaho requested that the EPA remove the ordinances in Table 1 of this preamble from the Idaho SIP.

Table 1—Local I/M Ordinances That Idaho Requests Be Removed From the Northern Ada County CO SIP

Local agency	Ordinance title	Local agency approval date
Air Quality Board	Motor Vehicle Emissions Control Ordinance	1/1/2010
Ada County	The 1999 Motor Vehicle Emissions Control Ordinance	6/15/1999
City of Boise	The 1999 Motor Vehicle Emissions Control Ordinance	7/20/1999
City of Eagle	The 1999 Motor Vehicle Emissions Control Ordinance	4/27/1999
City of Garden City	The 1991 Vehicle Emission Control Ordinance	8/13/1996
City of Meridian	The 1999 Motor Vehicle Emissions Control Ordinance	6/1/1999

On December 29, 2022, Idaho submitted a SIP revision to the EPA that removes the I/M program from the Northern Ada County CO area SIP.

II. Requirements of CAA Section 110( l )

CAA section 110( l) provides that “. . . The Administrator shall not approve a revision of a plan if the revision would interfere with any applicable requirement concerning attainment and reasonable further progress (as defined in [CAA section 171]) or any other applicable requirement of [the CAA].” 42 U.S.C. 7410( l). CAA section 110( l) applies to all requirements of the CAA and to all areas of the country, whether attainment, nonattainment, unclassifiable or maintenance for one or more of the six criteria pollutants. Before the EPA can conclude that the SIP revision is allowed under CAA section 110( l ), the EPA must first conclude that the particular plan revision meets CAA requirements.^[4]

The EPA interprets CAA section 110( l ) as applying to all NAAQS that are in effect, including those for which SIP submissions have not been made, therefore the EPA considers the impact of the SIP revision on emissions and/or ambient concentrations of any pollutant. Additionally, in certain circumstances a state may demonstrate non-interference with CAA applicable requirements by substituting equivalent emissions reductions to compensate for any change to a plan to ensure actual emissions to the air are not increased and thus preserve status quo air quality.^[5]

III. Evaluation of Submission

A. Monitoring Values and Event Data

Idaho evaluated air quality design values in the Northern Ada County CO area for CO, NO₂, O₃, SO₂, PM_2.5 and PM₁₀ .^[6 7 8] The design values included in Idaho's submission were based on the latest available data when the SIP revision was developed and submitted.

Idaho operates two CO monitoring sites in the Northern Ada County CO area and provided CO design values from 2017 to 2021. As shown in Table 2 of this preamble, the 8-hour CO design values ranged from 0.7 parts per million (ppm) to 4.1 ppm and were well below the 9 ppm 8-hour CO NAAQS.^[9] The 1-hour CO design values, shown in Table 3 of this preamble, were also well below the 35 ppm 1-hour CO NAAQS, ranging from 1.0 ppm to 15.9 ppm during the same time period.

Table 2—2017–2021 CO 1-Hour Design Values

[ppm]

Site name	AQS ID	2016–2017	2017–2018	2018–2019	2019–2020	2020–2021
Meridian St. Luke's	160010010	1.4	1.0	1.0	1.09	1.0
Boise Eastman	160010014	15.9	15.9	4.6	2.5	2.5

Table 3—2017–2021 CO 8-Hour Design Values

[ppm]

Site name	AQS ID	2016–2017	2017–2018	2018–2019	2019–2020	2020–2021
Meridian St. Luke's	160010010	4.1	4.1	1.6	0.9	0.9
Boise Eastman	160010014	0.9	0.7	1.6	1.5	1.5

In the second quarter of 2019, Idaho began reporting year-round monitoring data for NO₂ for the Northern Ada County CO area (AQS ID 160010010). The 1-hour NO₂ design value is the 3-year average of the 98th percentile of the 1-hour daily maximum, and the NO₂ NAAQS is 100 parts per billion (ppb).^[10] Because there is not complete NO₂ monitoring data for the first quarter of 2019, we do not have a valid NO₂ design value for the area. However, Idaho provided the 98th percentiles for 2019, for quarters 2 through 4 (40.8 ppb), and for all quarters of 2020 (43.1 ppb) and 2021 (45.1 ppb). Based on this data, Idaho calculated the 3-year average of 98th percentile of 43 ppb, which is below the 100 ppb NO₂ NAAQS. The annual NO₂ NAAQS is calculated as the annual mean. The annual NO₂ mean for the Northern Ada County CO area was 9.84 ppb in 2021 and 9.59 ppb in 2020. These values are well below the 53 ppb annual NO₂ NAAQS.

Idaho provided design values for the two ozone monitoring sites in the Northern Ada County CO area. The 2019–2021 ozone design values were 0.065 ppm (AQS ID 160010010) and 0.063 ppm (AQS ID 160010017). These design values are below the 2015 8-hour ozone NAAQS of 0.070 ppm.^[11]

Idaho also provided the 2019–2021 1-hour SO₂ design value for the Northern Ada County CO area. The 2 ppb design value (AQS ID 160010010) is well below the 75 ppb 1-hour SO₂ NAAQS.

Idaho operates two PM_2.5 monitors in the Northern Ada County CO area. The 2019–2021 24-hour PM_2.5 design value at the Meridian St. Luke's monitoring site is 30 micrograms per cubic meter (μg/m^[3] ) (AQS ID 160010010). This is below the 35 μg/m^[3] 24-hour PM_2.5 NAAQS. The 2019–2021 annual PM_2.5 design value at this site is 7.3 μg/m^[3] . This is also below the annual 12.0 μg/m^[3] PM_2.5 NAAQS.^[12]

Idaho operates two PM₁₀ monitors in the Northern Ada County CO area. The 2019–2021 24-hour PM₁₀ design value at the Boise Fire Station #5 monitoring site is 0.0 (the number of expected exceedances). Because of incomplete data, Idaho does not have valid PM_2.5 or PM₁₀ 2019–2021 design values for the Nampa Fire Station monitoring site (AQS ID 160270002).^[13]

B. Vehicle Emission Trends in Idaho

In the December 29, 2022, SIP submission seeking removal of the I/M program, Idaho provided an evaluation of projected changes in on-road mobile source emissions through 2040. Idaho's submission shows that vehicle miles traveled (VMT) are projected to increase through 2040. However, older cars continue to be replaced with newer, cleaner models that have more stringent emissions controls and higher fuel efficiencies. Idaho explained that this fleet turnover has led to the I/M program achieving fewer emissions reductions each year in the Northern Ada County CO area. Idaho used the EPA's MOVES3 ^[14] model to assess emissions for years 2015, 2020, 2022, 2025, 2030, 2035, and 2040. Idaho's analysis focused on carbon monoxide (CO), nitrogen oxides (NO_X), volatile organic compounds (VOCs), and fine particulate matter (PM_2.5) emissions.^[15]

Idaho analyzed projected on-road mobile source emissions for CO, NO_X, and VOCs in the Northern Ada County CO area and determined that the area will continue to see emissions decrease through 2040, both with and without the I/M program in effect. These reductions are primarily expected from fleet turnover and implementation of more stringent Federal motor vehicle emission standards in newer vehicles. Based on Idaho's projections, through 2040, the I/M program accounts for an 11%–12% reduction in total annual onroad CO emissions, 2%–3% reduction in total annual onroad NOx emissions, and a 5% reduction in total annual VOC emissions. Based on these projections, even without the I/M program in place, Ada County CO, NOx and VOC emissions will continue to decrease.

Idaho also estimated long-term emission reductions. Idaho used MOVES modeling to project emissions to an outlying year of 2040. Table 4 of this preamble shows seasonal projected percent reductions in total emissions in the Northern Ada County CO area without the I/M program in place from 2015 to 2040 and from 2022, the last year of the I/M program, to 2040. For total CO and NO_X emissions, Idaho analyzed summer season (June through August), winter season (December through February), and ozone season (April through September) total emissions. For total VOC emissions, Idaho analyzed summer and ozone season emissions. For PM_2.5, Idaho analyzed winter season emissions. Idaho selected the seasons for each pollutant according to when emissions from motor vehicles are expected to have the highest concentrations. Ozone season was selected for NO_X and VOCs because they are precursors to ozone. In the winter, multiday air stagnation events are common in the area and result in elevated concentrations for all pollutants.

Table 4—Percent Reduction in Total Emissions by Selected Seasons in the Northern Ada County CO Area Without the I/M Program From 2015 to 2040 and From 2022 to 2040

Pollutant	Season	2015–2040 (%)	2022–2040 (%)
CO	Summer	62	46
	Winter	53	40
	Ozone Season	63	45
NO X	Summer	72	48
	Winter	69	47
	Ozone Season	72	46
VOC	Summer	60	36
	Ozone Season	59	34
PM 2.5	Winter	45	17

Idaho attributes the long-term emissions reductions in the area, without the I/M program, to more stringent Federal motor vehicle emissions standards in newer vehicles and continuing fleet turnover. Idaho notes that on-road winter PM_2.5 emissions increase slightly starting in 2040 when projected increases in population growth, vehicle population, and VMT begin to outweigh the emissions benefits from stricter Federal motor vehicle emissions standards. Idaho also notes that the MOVES3 model does not calculate on-road PM_2.5 emissions benefits from the I/M program.

The EPA reviewed the on-road modeling performed by Idaho. The emission trends analysis shows that any changes in emissions associated with the removal of the I/M program are expected to be relatively minor compared to the emission reductions associated with the turnover of older, higher-emitting vehicles for newer, lower-emitting vehicles.

In summary, emissions in the Northern Ada County CO area are projected to decrease even if the I/M program is discontinued. This continued projected decrease in emissions, despite projected increases in VMT, is expected due to fleet turnover and more stringent Federal vehicle standards.

C. Conclusion

The Northern Ada County CO area is attaining the NAAQS with current on-road emission levels. On-road emissions will continue to decrease as older vehicles are replaced with newer, lower-emitting vehicles and these decreases are projected to continue despite population growth due to Federal motor vehicle emissions standards even if this SIP revision is approved.

The emission trends analysis in the SIP revision, shows that on-road emissions in the Northern Ada County CO area will generally continue to decrease even if the proposed SIP revision is approved. Based on our evaluation of the analysis submitted by the state of Idaho, the EPA concludes that the removal of the I/M program will not interfere with attainment or maintenance of the NAAQS.

IV. What action is the EPA proposing?

The EPA is proposing to approve the Idaho SIP revision requesting to remove the Northern Ada County I/M program from the Idaho SIP. Specifically, the EPA is proposing to revise the Northern Ada County Air Quality Maintenance Area Second 10-year Carbon Monoxide Limited Maintenance Plan in 40 CFR 52.670(e) and remove the following local ordinances from incorporation by reference in 40 CFR 52.670(c):

State citation	Title/subject	State effective date
Ada County Ordinance	The 1999 Motor Vehicle Emissions Control Ordinance	6/15/1999
City of Boise Ordinance	The 1999 Motor Vehicle Emissions Control Ordinance	7/20/1999
City of Eagle Ordinance	The 1999 Motor Vehicle Emissions Control Ordinance	4/27/1999
City of Garden City Ordinance	The 1991 Vehicle Emission Control Ordinance	8/13/1996
City of Meridian Ordinance	The 1999 Motor Vehicle Emissions Control Ordinance	6/1/1999

The EPA believes that Idaho's demonstration that removal of the I/M program will not interfere with any applicable requirement concerning attainment and RFP, or any other applicable requirement of the CAA meets CAA section 110( l) requirements. The EPA is requesting comments on the proposed approval.

V. Incorporation by Reference

In this document, the EPA is proposing to remove, in a final EPA rule, regulatory text that includes incorporation by reference. In accordance with requirements of 1 CFR 51.5, the EPA is proposing to remove the local ordinances identified in section IV of this preamble. The EPA has made, and will continue to make, these materials generally available through https://www.regulations.gov and at the EPA Region 10 Office (please contact the person identified in the FOR FURTHER INFORMATION CONTACT section of this preamble for more information).

VI. Statutory and Executive Order Reviews

Under the CAA, the EPA Administrator is required to approve a SIP submission that complies with the provisions of the CAA 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 CAA. Accordingly, this action merely approves state law as meeting Federal requirements and does not impose additional requirements beyond those already 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 Orders 12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);

• 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 an economically significant regulatory action based on health or safety risks subject to Executive Order 13045 (62 FR 19885, April 23, 1997);
• Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001);
• 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; and
• Does not provide the EPA with the discretionary authority to address, as appropriate, disproportionate human health or environmental effects, using practicable and legally permissible methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).

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, this rule does not have tribal implications as specified by Executive Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects in 40 CFR Part 52

• Environmental protection
• Air pollution control
• Carbon monoxide
• Incorporation by reference
• Intergovernmental relations
• Lead
• Nitrogen dioxide
• Ozone
• Particulate matter
• Reporting and record keeping requirements
• Sulfur oxides
• Volatile organic compounds

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

Dated: March 23, 2023.

Casey Sixkiller,

Regional Administrator, Region 10.

Footnotes

1.  Under CAA section 107(d)(1)(C), any area that was designated nonattainment before enactment of the Clean Air Act Amendments of 1990 was to retain the designation upon enactment by operation of law. The CO nonattainment areas that had not violated the CO standard in either year of the two-year period 1988–1989 were to be designated nonattainment with the classification “not classified.” Accordingly, on November 6, 1991, the Boise-Northern Ada County CO area was designated nonattainment for the CO NAAQS by the EPA with a classification of “not-classified” (56 FR 56818, November 6, 1991).

2.  See “Transportation Conformity Guidance for Areas Reaching the End of the Maintenance Period,” available at: https://nepis.epa.gov/​Exe/​ZyPDF.cgi/​P100KPP0.PDF?​Dockey=​P100KPP0.PDF.

3.  See 84 FR 2109 at pg. 2111 (February 6, 2019).

4.   Hall v. EPA, 273 F.3d 1146, 1160 (9th Cir. 2001).

5.  See Hall v. EPA, 273 F.2d at 1160 n. 11; 1161 n. 12 (reasoning that the “no relaxation” test would clearly be appropriate in areas attaining the NAAQS).

6.  For a review of the National Ambient Air Quality Standards, averaging time, and form, please visit https://www.epa.gov/​criteria-air-pollutants/​naaqs-table.

7.  A design value is a statistic that describes the air quality status of a given location relative to the level of the National Ambient Air Quality Standards (NAAQS). See https://www.epa.gov/​air-trends/​air-quality-design-values#:~:text=​Design%20Value%20Reports-,What%20is%20a%20Design%20Value%3F,in%2040%20CFR%20Part%2050%20.

8.  See the EPA's September 14, 2022, approval of Idaho's Annual Monitoring Network Plan, included in the docket for this action.

9.  40 CFR 50.8.

10.  40 CFR 50.11.

11.  40 CFR 50.19.

12.  40 CFR 50.18.

13.  Because of incomplete data, Idaho does not have valid PM 2019–2021 design values for the Nampa Fire Station monitoring site (AQS ID 160270002), however, Idaho calculated estimated design values at that location using the available data. The estimated 24-hour PM_2.5 design value is 35 μg/m3. , and the estimated annual PM_2.5 design value is 8.9 μg/m3. . The estimated PM₁₀ design value is 0.0.

14.  The EPA's MOtor Vehicle Emission Simulator (MOVES) is a state-of-the-science emission modeling system that estimates emissions for mobile sources at the national, county, and project level for criteria air pollutants, greenhouse gases, and air toxics. See https://www.epa.gov/​moves/​latest-version-motor-vehicle-emission-simulator-moves.

15.  NO_X and VOCs are precursors to ozone. Ozone is a criteria pollutant that is formed in photochemical reactions in the atmosphere involving NO_X and VOCs. Onroad vehicles are not a significant source of Pb or PM₁₀ emissions. Therefore, removal of the I/M program is not expected to interfere with attainment or maintenance of the Pb or PM₁₀ NAAQS.