Approval and Promulgation of Air Quality Implementation Plans; Wisconsin; Milwaukee-Racine Nonattainment Area; Determination of Attainment for the 2006 24-Hour Fine Particle Standard

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On April 24, 2012, EPA proposed to determine that the Milwaukee-Racine, Wisconsin area had attained the 2006 24-hour fine particle (2006 PM 2.5 ) National Ambient Air Quality Standard (NAAQS). EPA received several comments on the original proposal, including one suggesting that the suspension of certain Clean Air Act (CAA) requirements cannot be applied in this instance because it only pertains to the 1997 PM 2.5 NAAQS and not to the 2006 PM 2.5 NAAQS. As a result, we are reproposing a narrow portion of our original determination to address this issue. We will address all comments received on the original proposal and this proposal in our final notice.