Determination of Attainment by the Attainment Date but for International Emissions for the 2015 Ozone National Ambient Air Quality Standards; Phoenix-Mesa Nonattainment Area, Arizona

ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Part 52</CFR> <DEPDOC>[EPA-R09-OAR-2025-2833; FRL-13057-01-R9]</DEPDOC> <SUBJECT>Determination of Attainment by the Attainment Date but for International Emissions for the 2015 Ozone National Ambient Air Quality Standards; Phoenix-Mesa Nonattainment Area, Arizona</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Environmental Protection Agency (EPA). <HD SOURCE="HED">ACTION:</HD> Proposed rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The Environmental Protection Agency (EPA or “Agency”) is proposing to determine that the Phoenix-Mesa nonattainment area (“Phoenix-Mesa area”) would have attained the 2015 ozone national ambient air quality standards (NAAQS) by the August 3, 2024 “Moderate” area attainment date, but for emissions emanating from outside the United States. If we finalize this proposed action, the Phoenix-Mesa area would no longer be subject to the Clean Air Act (CAA) requirements pertaining to reclassification upon failure to attain and therefore would remain classified as a Moderate nonattainment area for the 2015 ozone NAAQS. This action, when finalized, will fulfill the EPA's statutory obligation to determine whether the Phoenix-Mesa area attained the NAAQS by the attainment date. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> Comments must be received on or before December 19, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> Submit your comments, identified by Docket ID No. EPA-R09-OAR-2025-2833 at <E T="03">https://www.regulations.gov.</E> For comments submitted at <E T="03">Regulations.gov</E> , follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from <E T="03">Regulations.gov</E> . 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 ( <E T="03">i.e.,</E> on the web, cloud, or other file sharing system). For additional submission methods, please contact the person identified in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section. For the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit <E T="03">https://www.epa.gov/dockets/commenting-epa-dockets.</E> If you need assistance in a language other than English or if you are a person with disabilities who needs a reasonable accommodation at no cost to you, please contact the person identified in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Karina O'Connor, EPA Region IX, 75 Hawthorne St., San Francisco, CA 94105; telephone number: (415) 725-8713, email address: <E T="03">oconnor.karina@epa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> Throughout this document “we,” “us,” or “our” refer to the EPA. <HD SOURCE="HD1">Table of Contents</HD> <EXTRACT> <FP SOURCE="FP-2">I. Background</FP> <FP SOURCE="FP1-2">A. 2015 Ozone National Ambient Air Quality Standard and Area Designations</FP> <FP SOURCE="FP1-2">B. Clean Air Act Requirements for Moderate Ozone Nonattainment Areas</FP> <FP SOURCE="FP1-2">C. Requirement for Determination of Attainment of the 2015 Ozone NAAQS</FP> <FP SOURCE="FP1-2">D. International Transport and Clean Air Act Section 179B</FP> <FP SOURCE="FP1-2">E. Exceptional Events and Other Data Modification</FP> <FP SOURCE="FP-2">II. Phoenix-Mesa Ozone Determination of Attainment but for International Emissions</FP> <FP SOURCE="FP1-2">A. Phoenix-Mesa Ozone Nonattainment Area</FP> <FP SOURCE="FP1-2">B. Ozone Monitoring Sites in Phoenix-Mesa</FP> <FP SOURCE="FP1-2">C. Summary of the State's Submission</FP> <FP SOURCE="FP1-2">D. EPA Review of the State's Submission</FP> <FP SOURCE="FP-2">III. Proposed Action</FP> <FP SOURCE="FP-2">IV. Statutory and Executive Order Reviews</FP> <FP SOURCE="FP1-2">A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review</FP> <FP SOURCE="FP1-2">B. Executive Order 14192: Unleashing Prosperity Through Deregulation</FP> <FP SOURCE="FP1-2">C. Paperwork Reduction Act (PRA)</FP> <FP SOURCE="FP1-2">D. Regulatory Flexibility Act (RFA)</FP> <FP SOURCE="FP1-2">E. Unfunded Mandates Reform Act (UMRA)</FP> <FP SOURCE="FP1-2">F. Executive Order 13132: Federalism</FP> <FP SOURCE="FP1-2">G. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments</FP> <FP SOURCE="FP1-2">H. Executive Order 13045: Protection of Children From Environmental Health and Safety Risks</FP> <FP SOURCE="FP1-2">I. Executive Order 13211: Actions That Significantly Affect Energy Supply, Distribution, or Use</FP> <FP SOURCE="FP1-2">J. National Technology Transfer Advancement Act (NTTAA)</FP> </EXTRACT> <HD SOURCE="HD1">I. Background</HD> <HD SOURCE="HD2">A. 2015 Ozone National Ambient Air Quality Standard and Area Designations</HD> Ground-level ozone pollution is formed from the reaction of volatile organic compounds (VOC) and oxides of nitrogen (NO <E T="52">X</E> ) in the presence of sunlight. These two pollutants, referred to as ozone precursors, are emitted by many types of sources, including on- and non-road motor vehicles and engines, power plants and industrial facilities, and smaller area sources such as lawn and garden equipment and paints. Scientific evidence indicates that adverse public health effects occur following exposure to ground-level ozone pollution. Exposure to ozone can harm the respiratory system (the upper airways and lungs), can aggravate asthma and other lung diseases, and is linked to premature death from respiratory causes. People most at risk from breathing air containing ozone include people with asthma, children, older adults, and people who are active outdoors, especially outdoor workers. <SU>1</SU> <FTREF/> <FTNT> <SU>1</SU>  EPA Fact Sheet—Ozone and Health, available at <E T="03">https://www.epa.gov/sites/default/files/2016-04/documents/20151001healthfs.pdf</E> and in the docket for this action. </FTNT> Under CAA section 109, the EPA promulgates NAAQS (or “standards”) for pervasive air pollutants, such as ozone. The EPA has previously promulgated NAAQS for ozone in 1979, 1997, and 2008. <SU>2</SU> <FTREF/> On October 26, 2015, the EPA revised the NAAQS for ozone to establish new 8-hour standards. <SU>3</SU> <FTREF/> In that action, the EPA promulgated identical revised primary and secondary ozone standards designed to protect public health and welfare that specified an 8-hour ozone level of 0.070 parts per million (ppm). <SU>4</SU> <FTREF/> Specifically, the standards require that the 3-year average of the annual fourth highest daily maximum 8-hour average ozone concentration ( <E T="03">i.e.,</E> the design value) may not exceed 0.070 ppm. <SU>5</SU> <FTREF/> When the design value (DV) does not exceed 0.070 ppm at each ambient air quality monitoring site within the area, the area is deemed to be attaining the ozone NAAQS. <SU>6</SU> <FTREF/> <FTNT> <SU>2</SU>  44 FR 8202 (February 8, 1979), 62 FR 38856 (July 18, 1997), and 73 FR 16436 (March 27, 2008). </FTNT> <FTNT> <SU>3</SU>  80 FR 65292. </FTNT> <FTNT> <SU>4</SU>  Because the 2015 primary and secondary NAAQS for ozone are identical, for convenience, the EPA refers to them in the singular as “the 2015 ozone NAAQS” or as “the standard.” </FTNT> <FTNT> <SU>5</SU>  A design value is a statistic used to compare data collected at an ambient air quality monitoring site to the applicable NAAQS to determine compliance with the standard. The design value for the 2015 ozone NAAQS is the 3-year average of the annual fourth highest daily maximum 8-hour average ozone concentration. The design value is calculated for each air quality monitor in an area and the area's design value is the highest design value among the individual monitoring sites in the area. </FTNT> <FTNT> <SU>6</SU>  The data handling convention in 40 CFR part 50, appendix U dictates that concentrations shall be reported in “ppm” to the third decimal place, with additional digits to the right being truncated. Thus, a computed 3-year average ozone concentration of 0.071 ppm is greater than 0.070 ppm and would exceed the standard, but a design value of 0.0709 is truncated to 0.070 and attains the 2015 ozone NAAQS. </FTNT> Section 107(d) of the CAA provides that when the EPA promulgates a new or revised NAAQS, the Agency must designate areas of the country as nonattainment, attainment, or unclassifiable based on whether an area is not meeting (or is contributing to air quality in a nearby area that is not meeting) the NAAQS, meeting the NAAQS, or cannot be classified as meeting or not meeting the NAAQS, respectively. Subpart 2 of part D of title I of the CAA governs the classification, state planning, and emissions control requirements for any areas designated as nonattainment for a revised primary ozone NAAQS. In particular, CAA section 181(a)(1) also requires the EPA to classify each ozone nonattainment area at the time of designation, based on the extent of the ozone problem in the area (based on the area's DV). Classifications for ozone nonattainment areas range from “Marginal” to “Extreme.” CAA section 182 provides the specific attainment planning and additional requirements that apply to each ozone nonattainment area based on its classification. CAA section 182, as i ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 82k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━