Implications of Arizona’s New Ozone Nonattainment Area
June 2004

Portions of Maricopa County have been designated nonattainment for ozone since 1978. Due to the combined efforts of the regulated community and regulators alike, air quality in Maricopa County has significantly improved. In fact, since 1996 Maricopa County has met the 1-hour ozone NAAQS.

However, any hopes of eventually eliminating ozone nonattainment requirements were fleeting. On April 15, 2004, EPA raised the bar and designated nonattainment areas for the “new” 8-hour ozone NAAQS. Large portions of Maricopa County as well as the Pinal County portion of Apache Junction have been designated nonattainment for the new standard, which becomes effective June 15, 2004.

The new nonattainment area for the 8-hour standard will be classified as a “basic” nonattainment area, subject to the requirements of the CAA, Title I, Part D, Subpart 1. Subpart 1 contains general nonattainment requirements and is more flexible, less prescriptive, than Subpart 2, which contains specific, rigid requirements for most ozone nonattainment areas, including the existing 1-hour area.

Concurrent with the 8-hour nonattainment designation and “basic” classification, EPA also released the first phase of the implementation requirements for planning and control measures in these areas. This phase provides attainment dates and the framework for the transition from the 1-hour standard to the 8-hour standard. Of considerable interest to many in the regulated community, serious area New Source Review (NSR) requirements will no longer be required by EPA.

EPA has not yet released the second phase of the implementation rule, which will detail the new requirements for reasonably available control measures (RACM), reasonable available control technology (RACT), attainment demonstrations, and planning requirements. As a result, many questions remain concerning the impact of the designation. EPA’s current requirements for 1-hour nonattainment areas and proposed requirements for 8-hour areas provide some guidance on what the regulated community can expect.

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