Today, Illinois has two areas designated as nonattainment for ozone, the Chicago and Saint-Louis (Metro-East) metropolitan areas. These areas were classified pursuant to the 1997 8-hour ozone standard of 0.08 ppm. In March 2008, U.S. EPA issued a new 8-hour ozone standard of 0.075 ppm. However, in September 2009, U.S. EPA announced that they were reconsidering the March 2008 standard, putting the state designation recommendations in limbo.

In January 2010, U.S. EPA proposed a revised 8-hour ozone standard in the range of 0.060 - 0.070 ppm. A final standard was to be selected by August 2010, but was never finalized. Finally, last September President Obama asked U.S. EPA to withdraw any forthcoming revised standard. This move reinstated the March 2008 8-hour ozone standard (0.075 ppm) and restarted the designation process. Subsequently, in December 2011 U.S. EPA issued a letter to Illinois indicating agreement with the preliminary nonattainment designation, based primarily on 2008 to 2010 monitoring data, which includes only Madison, Monroe, and St Clair Counties in the Metro-East area. U.S. EPA intends to designate all other areas of the state and unclassifiable/attainment. However, the letter stipulated that U.S. EPA has not had time to review 2011 monitoring data, which could alter the preliminary designations. Illinois has expressed concern with 2011 monitoring data demonstrating that the Chicago area would no longer be in 'attainment'. U.S. EPA has indicated that it intends to finalize designations by Spring 2012.

Meanwhile, Illinois and U.S. EPA have been working towards finalizing redesignation under the 1997 8-hr ozone standard of all areas to "attainment". Maintenance Plans, which the state must submit to U.S. EPA in order for an area to be considered for redesignation, have been finalized for both the Chicago and Metro-East areas. The Chicago area is further in the process, and could be declared as "attainment" early 2012.

In summary, both the redesignation process under the 1997 8-hr ozone standard and designation under the March 2008 8-hr ozone standard will likely cause changing attainment classifications in 2012. Currently, it appears that Jersey County of the Metro-East area is destined for an 'attainment' designation while the remaining portions of the Metro-East area will remain in 'nonattainment'. However, timing could result in a brief window in which the whole area is considered attainment. It also looks like the Chicago area is headed towards 'attainment', but further review of 2011 data may change its fate. This dynamic situation could impact any projects being permitted in the next several months. Stay tuned!