County Affected:

Yuma County | View on a Map >

Nonattainment Area Designation Date:

June 4, 2018

Learn more about the designation of the area in the Federal Register (83 FR 25786, Page 10) |  View >

Classification Level: 

Marginal

Pollutant of Concern:

Ozone (2015 standard; 70 ppb)

Summary: 

The concentration of ozone in the air in Yuma is frequently above the federal limit established in the federal National Ambient Air Quality Standards (NAAQS). ADEQ has submitted a nonattainment State Implementation Plan (SIP) to improve the area's air quality. Additionally, ADEQ has requested that the U.S. Environmental Protection Agency (EPA) redesignate the Yuma Ozone Nonattainment Area to attainment for the 2015 Ozone NAAQS. The Clean Air Act (CAA) requires that ADEQ include an updated emissions inventory, a modeled attainment demonstration and a strategy for possible exceptional events demonstrations and rules for ozone controls. ADEQ has worked with permitted facilities, local government, and community stakeholders in a collaborative effort to develop the SIP.

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Regulatory Background:

In 2015, EPA revised the NAAQS for ozone by lowering the level of the standard to 70 ppb. On June 4, 2018, EPA finalized the air quality designations for the Yuma area by adopting Arizona’s designation recommendation. In the same action, EPA classified Yuma as a marginal nonattainment area. Pursuant to CAA section 110(a)(1), which requires states to submit SIP revisions addressing the “infrastructure” of the state’s air quality management programs within three years following the promulgation of new or revised NAAQS, ADEQ submitted infrastructure SIP revisions to EPA on Sept. 24, 2018 | Learn More > 

Under CAA section 182(a), Arizona was required to submit a revised SIP for the Yuma Nonattainment Area within two years from the effective date of the nonattainment destination. ADEQ submitted this SIP revision to EPA on Dec. 22, 2020. 

On Oct. 7, 2022, EPA determined, in accordance with CAA section 181(b)(2)(A) and the provisions of the Ozone NAAQS SIP Requirements Rule (40 CFR 51.1303), that the Yuma area attained the 2015 ozone NAAQS by the marginal area attainment date of Aug. 3, 2021. EPA based its determination on ambient air quality data for the period of 2018-2020. The nonattainment designation remains until EPA determines that the planning area meets additional CAA provisions required for redesignation. ADEQ submitted a redesignation request and maintenance plan to EPA in December 2023.

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