In a memo from Assistant Administrator Gina McCarthy to regional air directors, EPA announced its intent to enforce and implement the 75 ppb ozone standard issued in 2008. The implementation of the 2008 standard had been on hold while EPA reconsidered the standard. The recent White House announcement of delaying the ozone reconsideration to 2013-2014 prompted EPA to revert back to the existing 2008 standard.
EPA is working on ozone nonattainment area designations based on the 2009 state recommendations, as well as updated air quality data. Initial nonattainment area designations may be issued by mid-2012 but could be influenced by ongoing litigation.
EPA’s memo is available here: http://www.epa.gov/glo/pdfs/OzoneMemo9-22-11.pdf
A summary table of expected nonattainment areas is available here: http://www.epa.gov/glo/pdfs/OzoneTable9-22-11.pdf