# Air Plan Approval; Oregon; 2024 Vehicle Inspection Program Updates
**AGENCY:**
Environmental Protection Agency (EPA).
**ACTION:**
Proposed rule.
**SUMMARY:**
The Environmental Protection Agency (EPA) proposes to approve revisions to the Oregon State Implementation Plan (SIP) submitted by the Oregon Department of Environmental Quality on April 3, 2025. The SIP revision updates rules for the Vehicle Inspection Program (VIP) which is applicable in the Portland and Medford areas, and includes a demonstration that the requested revisions 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).
**DATES:**
Comments must be received on or before October 27, 2025.
**ADDRESSES:**
Submit your comments, identified by Docket ID No. EPA-R10-OAR-2025-0181 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 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, 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:**
Tess Bloom, EPA Region 10, 1200 6th Ave., Seattle, WA 98101, at (206) 553-6362, or *[email protected].*
**SUPPLEMENTARY INFORMATION:**
Throughout this document, wherever “we,” “us,” or “our” is used, it is intended to refer to the EPA.
**Table of Contents**
I. Background
II. Evaluation of Revisions
III. Proposed Action
IV. Incorporation by Reference
V. Statutory and Executive Order Reviews
**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 criteria pollutants (carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter, sulfur dioxide). The SIP contains elements such 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.
The Oregon SIP includes VIP program rules for the Portland and Medford areas to maintain compliance with the NAAQS. The Portland area is part of the Portland-Vancouver air quality maintenance area (AQMA) for ozone (62 FR 27204, May 19, 1997). Medford, Oregon is a maintenance area for CO (67 FR 48388, July 24, 2002). The Oregon Department of Environmental Quality (DEQ) implements and enforces the Oregon SIP through rules set out in the Oregon Administrative Rules. Chapter 340, Division 256—Motor Vehicles includes the provisions for Oregon's VIP. The vehicle testing schedule for the VIP coincides with the dates for vehicle registration generally, as a vehicle owner residing within the testing boundary must obtain a certificate of compliance before renewing their vehicle's registration. The Oregon legislature passed a bill in 2001 that changed the initial registration period for new vehicles from two years to four years (2001 HB 2132), which can be found in Oregon's statute, ORS 803.415. In 2004, DEQ completed a rulemaking to update the VIP rules to reflect this change. After the initial four-year registration period, vehicle registration must be renewed, and receive a passing emissions test, every two years. Although the initial four-year exemption has been in effect since 2004, explicit rule language prescribing that a vehicle is not required to obtain a certificate of compliance that the vehicle emissions controls are adequately maintained during this period was not previously included in the SIP. This SIP revision includes that update as well as other minor changes to the VIP rules.
**II. Evaluation of Revisions**
**A. Summary of Rule Changes**
DEQ revised the Oregon Administrative Rules (OAR) section 340-256-0010 to include non-substantiative changes including the addition of definitions for “fleet participant,” “host participant,” “test equipment,” and “VIP.” Some definitions in this section were renumbered to accommodate the new definitions. DEQ revised OAR 340-256-0300 to describe the scope of rules through 340-256-0471, where it previously only extended to 340-256-0465. OAR 340-256-0466 through 340-256-0471 are new, non-SIP approved state rules that relate to criteria for remote on-board diagnostic (OBD) test equipment and requirements for participation in Oregon's remote OBD testing program.
DEQ added a new provision under OAR 340-256-0300(4) to make explicit that new vehicles are exempt from on-board diagnostic (OBD) test requirements of the VIP program contained in OAR 340-256-0355 until January 1st of the calendar year that is four years after a vehicle's designated model year. DEQ also revised OAR 340-256-0370 to clarify the Oregon vehicle inspection boundary, outside of which vehicles that are temporarily operating qualify for a temporary exemption from the vehicle testing requirement. Because the exemption only applies to vehicles that will be operating outside the inspection program's target areas, the EPA does not believe Oregon's minor clarifying changes to the exemption will result in impacts to the ambient air within these areas. Lastly, DEQ amended OAR 340-256-0465 to remove the word “licensing” in the title, to state that electronic vehicle test results be transferred to “DEQ online computer servers,” and requirement (3), “meeting additional fleet operations specifications as DEQ prescribes,” is removed.
**B. Vehicle Emission Trends in Oregon State**
The April 3, 2025, Oregon SIP revision includes an evaluation of projected changes in mobile source emissions that may be caused by the change in the vehicle inspection requirement from two to four years following a new vehicle's model year. The analysis focuses on the emissions of carbon monoxide (CO), nitrogen oxides (NOx), volatile organic compounds (VOCs), [^1] and fine particulate matter (PM <sub>2.5</sub> ). [^2] DEQ used the EPA's Motor Vehicle Emission Simulator (MOVES) model, version 4.0.1, to assess emissions for a typical day. MOVES 4.0.1 was the most recent version of MOVES available at the time work on this SIP began. The modeling demonstration in the SIP submittal compares vehicle emissions with the testing exemption for the first four model years to a baseline exemption of the first two model years based on vehicle data for 2023. DEQ chose to use a two-year exemption as a baseline because in the Portland and Medford areas, vehicles receive an emissions test on a biennial schedule. [^3] Additionally, although the four-year testing exemption has already been in effect since 2004, only the biennial testing schedule was made explicit in the SIP. Therefore, modeling completed by DEQ is consistent with what is currently approved into the SIP.
[^1] Both nitrogen oxides and volatile organic compounds are precursors to the formation of ozone and fine particulate matter.
[^2] Fine particulate matter, also known as PM <sub>2.5</sub> , refers to tiny particles and droplets in the air that are 2.5 micrometers or less in diameter. Particulate matter that is less than 10 micrometers in diameter (PM <sub>10</sub> ) was not analyzed due to on-road sources contributing a small percentage to the overall PM <sub>10</sub> concentrations.
[^3] The final rule by the EPA, “Approval and Promulgation of State Implementation Plans; Oregon,” published on September 9, 1994, includes more information about the EPA's approval of Oregon's inspections of motor vehicles on a biennial schedule.
The EPA reviewed the on-road modeling performed by the DEQ. Based on this modeling, motor vehicle emissions in the four impacted Oregon Counties are generally projected to decrease even with the exemption from emissions testing for the first four model years after a vehicle is new. This continued decrease in emissions, despite increases in vehicle miles travelled (VMT), [^4] are the result of fleet turnover, with old vehicles being replaced with new vehicles that meet more stringent engine standards. The downward trend of emissions from on-road sources is reflected in the EPA's 2020 National Emissions Inventory (NEI) and Trends Report. Specifically, the NEI Tool found on the 2020 NEI website [^5] demonstrates that from 2008 until 2020, criteria pollutant emissions from on-road mobile sources in Oregon steadily decreased. This included a decrease in VOCs, NO <sub>X</sub> , CO emission, and PM <sub>2.5</sub> emissions. Table 1 below includes data from the NEI tool that illustrates the change in light-duty, non-diesel, on-road vehicle emissions from 2008 until 2020.
[^4] The report released by the Oregon Department of Transportation, “2024 Statewide Congestion Overview,” contains more information about vehicle miles travelled trends in Oregon.
[^5]*https://storymaps.arcgis.com/stories/d7d730f974c6474190b142a49ae8d3bd/.*
| Pollutant | 2008 | 2011 | 2014 | 2017 | 2020 |
| --- | --- | --- | --- | --- | --- |
| CO | 471,154 | 408,167 | 357,552 | 265,810 | 213,816 |
| NO | 48,536 | 53,032 | 45,646 | 32,571 | 22,208 |
| VOCs | 37,753 | 39,561 | 34,414 | 27,699 | 21,244 |
| PM | 1,259 | 1,037 | 837 | 738 | 460 |
In sum, emissions are anticipated to continue decreasing into the future as the fleet turns over, despite projected increases in vehicle miles of travel in these areas.
**C. Monitoring Values and Attainment Status for Areas in Oregon**
All areas in the State of Oregon, with the exception of Klamath Falls which is primarily impacted by residential wood heating emissions rather than on-road emissions, [^6] are either designated as attainment/unclassifiable, unclassifiable, or attainment for the NAAQS. [^7] Areas are designated as attainment/unclassifiable when the design value shows it is below the NAAQS for the criteria pollutant in question. Areas are designated unclassifiable when there is insufficient data for either an attainment/unclassifiable or a nonattainment classification. Areas designated attainment have been redesignated to attainment with an approved maintenance plan. Designations are based on design values, which are calculated from monitoring data. The EPA most recently approved Oregon DEQ's annual monitoring network plan on May 16, 2025.
[^6] See 81 FR 36178 (June 6, 2016).
[^7] 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/.* For a review of current and historical designations in the State of Oregon by criteria pollutant, please visit *https://www.epa.gov/green-book/.*
DEQ assessed air quality design values for ozone, CO, and PM <sub>2.5</sub> in the four inspection and maintenance (I/M) counties as part of this submittal. The design values included in this submittal were based on 2000-2023 data for ozone and CO, and 1998-2023 data for PM <sub>2.5</sub> , which represented the most recently available data when the SIP was developed and submitted. Design values for ozone were below the NAAQS, besides elevated design values from 2017 to 2019 due to an increase in VOCs as a result of wildfires. [^8] Design values for CO were well below the NAAQS, except for a wildfire event in 2020 which caused an exceedance. [^9] PM <sub>2.5</sub> was also below the NAAQS for all years shown.
[^8] More information about the monitoring data, including contributions from wildfire emissions from 2017 to 2019, can be found in the 2019 Oregon Air Quality Monitoring Annual Report, which is included in the docket for this action.
[^9] More information about 2020 monitoring data can be found in the 2020 Oregon Air Quality Monitoring Annual Report, which is included in the docket for this action.
Additionally, as previously stated, the first four model years exemption from testing has already been in effect under state law since 2004 and all counties within the Portland-Vancouver maintenance area (Clackamas, Multnomah, and Washington) have been in attainment with the NAAQS since at least 2004. Medford is located in Jackson County, which has also been in attainment with the NAAQS since 2004.
**D. Clean Air Act Section 110(l)**
Section 110(l) of the CAA 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 or any other applicable requirement of the CAA.
As stated above, all areas within the State are designated attainment for all NAAQS, except for Klamath Falls, and concentrations of all relevant criteria pollutants are far below their respective NAAQS. These areas are attaining with current on-road emission levels and the four-year exemption. In addition, on-road emissions will continue to decrease as older vehicles are replaced with newer, lower-emitting vehicles, despite expected population growth. Based on this evaluation of Oregon's submittal, the EPA has determined that the revisions to Oregon's VIP program will not interfere with attainment or maintenance of the NAAQS and, therefore, this SIP revision is consistent with CAA section 110(l).
**III. Proposed Action**
We propose to approve into the Oregon SIP the submitted revisions to the Division 256 “Motor Vehicles” regulations, State effective January 10, 2025:
• OAR 340-256-0010 *Definitions,* specifying definitions for the motor vehicle program;
• OAR 340-256-0300 *Emission Control System Inspection: Scope,* specifying requirements under the vehicle inspection program;
• OAR 340-256-0370 *Emission Control System Inspection: Renewal of Registration for Light-duty Motor Vehicles and Heavy-duty Gasoline Motor Vehicles Temporarily Operating Outside of the Oregon Vehicle Inspection Boundaries,* specifying temporary geographic exemptions under the program; and
• OAR 340-256-0465 *Emission Control System Inspection: Test Equipment Licensing Criteria for OBD Test Program,* specifying requirements for On-Board Diagnostics.
These rules were submitted to the EPA by DEQ on April 3, 2025. Based on the demonstration provided by DEQ, we propose to approve these rule revisions.
**IV. Incorporation by Reference**
In this document, we are proposing to include in a final rule, regulatory text that includes incorporation by reference. In accordance with requirements of 1 CFR 51.5, the EPA is proposing to incorporate by reference the provisions described in section III of this document. The EPA has made, and will continue to make, these documents 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).
**V. 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. 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 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 subject to Executive Order 14192 (90 FR 9065, February 6, 2025) because SIP actions are exempt from review 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 CAA.
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).
**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 recordkeeping requirements, Sulfur oxides, Volatile organic compounds.
*Authority:* 42 U.S.C. 7401 *et seq.*
Dated: September 15, 2025.
Emma Pokon,
Regional Administrator, Region 10.