EPA is approving the extension of the attainment date from June 15, 2010 to June 15, 2011 for the Baltimore nonattainment area, which is classified as moderate for the 1997 8-hour ozone National Ambient Air Quality Standard (NAAQS). This extension is based on the air quality data for the 4th highest daily 8-hour monitored value during the 2009 ozone season. Accordingly, EPA is revising the table concerning the 8-hour ozone attainment dates in the State of Maryland. EPA is approving the extension of the attainment date for the Baltimore moderate ozone nonattainment area in accordance with the requirements of the Clean Air Act (CAA).