1-Hour and 8-Hour Ozone Category/Classification Information

These are the maximum attainment dates allowed under the Act; actual attainment dates must be as expeditious as practicable, but no later than these dates. Attainment dates will be approved and specified in 40 CFR Part 52 when EPA takes rulemaking on the 8 hour ozone SIPs.

These are 8-hour nonattainment areas that are covered under Subpart 1, Part D, Title I of the Clean Air Act. "Subpart 1" is not a classification, but are included in the table as an indication of the requirements under the CAA that apply to these areas.

On June 8, 2007, the United States Court of Appeals vacated the Subpart 1 portion of the Phase 1 Rule (Court Order). The Subpart 1 areas in the Greenbook are listed as "Former Subpart 1" until reclassification of the areas is finalized. Proposed reclassifications were published on January 16, 2009 ( 74 FR 2936)

Previous 1-Hour Ozone Classifications

Some of the previous 1-hr ozone area classifications have been adjusted, as follows:

On July 10, 1998 (63 FR 37258), EPA published the final rule redesignating the San Francisco Bay Area to nonattainment with the federal 1-hour ozone NAAQS. EPA did not assign the Bay Area a classification. Then on July 22, 1999 (64 FR 39416) EPA published a final rule assigning the area a nonattainment classification on moderate for purposes of funding appropriation under the Transportation Equity Act for the 21st Century (TEA 21), Congestion Mitigation and Air Quality Improvement Program (CMAQ) only.

Kansas City was the only area classified submarginal (listed under "other"), but it has been redesignated attainment. This category includes areas that violate the ozone standard and have a design value of less than 0.121 parts per million. This occurs when there is higher than the ozone standard exceedance rate of 1.0 per year even though the estimated design value is less than the level of the standard.

An area designated as an ozone nonattainment area as of the date of enactment of the Clean Air Act Amendments of 1990 and has not violated the national primary ambient air quality standard for ozone for the 36-month period commencing on January 1, 1987 and ending on December 31, 1989. Twelve areas were classified transitional in 1991. Section 185A of the Clean Air Act. "Transitional Area" lists the requirements for these areas.

An area designated as an ozone nonattainment area as of the date of enactment of the Clean Air Act Amendments of 1990 and did not have sufficient data to determine if it is or is not meeting the ozone standard.