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Technology Transfer Network / NAAQS
Ozone Implementation

Designations for the 8-Hour Ozone NAAQS

Information provided for informational purposes onlyNote: EPA no longer updates this information, but it may be useful as a reference or resource.

June 25, 1999


SUBJECT: Designations for the 8-Hour Ozone National Ambient Air Quality Standard

FROM: John S. Seitz, Director Office of Air Quality Planning and Standards

TO: Deputy Regional Administrators Regions I - X

As you know, the Transportation Equity Act for the 21st Century (TEA-21) modified the time line requirements of section 107(d) of the Clean Air Act (CAA). Now the Environmental Protection Agency (EPA) is required to designate areas for the 8-hour ozone National Ambient Air Quality Standards (NAAQS) by July 2000. The formal process for designating areas begins when State Governors or their designees submit nonattainment recommendations. The May 14, 1999, ruling by the D.C. Circuit Court raised issues on the 8-hour ozone and the particulate matter NAAQS. The court decision did not challenge the underlying health basis of the ozone NAAQS or the need to designate areas as attainment, nonattainment, or unclassifiable, nor did it vacate the 8-hour standard. Therefore, we believe that you should continue to work with your States as they develop the technical basis of their ozone designations.

To ensure that the process runs smoothly, please inform your States that they should submit by August 15, 1999 the most recent, complete, and quality assured air ozone monitoring data to EPA's Aerometric Information and Retrieval System (AIRS), with the data flags set for approved Mexican fire exceptions. States should identify the monitors where exceedances of the 8-hour standard have occurred. Also, please continue to work with your States to assess appropriate boundaries for nonattainment areas. We will advise you in late winter or early spring of our plans for proposing and finalizing designations. States will then have the opportunity to submit any additional information regarding their recommendations and boundary determinations.

If you have any questions on the designation process, please contact Sharon Reinders at 919-54l-5284.

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