In October U.S. EPA announced final action in the Federal Register to approve most elements of Michigan's State Implementation Plan (SIP) submissions regarding the infrastructure requirements of the Clean Air Act (CAA) for the 2006 24-hour fine particle (PM 2.5) national ambient air quality standards.
Then, a few days later EPA announced other final determinations under the CAA regarding the 1997 annual fine particle nonattainment area of Detroit-Ann Arbor, Michigan (Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw, and Wayne Counties) area:
EPA determined that the Detroit-Ann Arbor area has attained the 1997 annual PM 2.5 National Ambient Air Quality Standard (NAAQS)
- This was based upon complete, quality-assured, and certified ambient air monitoring data for 2009-2011, showing that the area has monitored attainment of the 1997 annual PM 2.5 NAAQS
- preliminary data available for 2012 indicates continued attainment.
this EPA determination suspends the requirements for the Detroit-Ann Arbor area to submit an attainment demonstration, associated reasonably available control measures (RACM) to include reasonably available control technology (RACT), a reasonable further progress (RFP) plan, contingency measures, and other planning SIP revisions related to attainment of the 1997 annual PM 2.5 NAAQS
- the area must continue to attain the PM 2.5 NAAQS to maintain the suspension
- EPA also determined, based on data for the 2007-2010 monitoring period, that the Detroit-Ann Arbor area had attained the 1997 annual PM 2.5 NAAQS by the its attainment date of April 5, 2010, thus avoiding further requirements.