DESIGNATIONS IN US EPA REGION 9 FOR THE 2010 PRIMARY 1-HOUR SULFUR DIOXIDE (S02) NATIONAL AMBIENT AIR QUALITY STANDARDS Areas being addressed in separate future actions51. The primary national ambient air quality standard (NAAQS)for 1-hour sulfur dioxide (S02) is 75 parts per billion (ppb). Air quality monitors in each area designated 'Nonattainment' have measured violations of the S02NAAQS. *Includes Commonwealth of Northern Mariana Islands and American Samoa (not shown on this map). (2012), 78 FR 47191 (August 5, 2013), ESRI (2006), TANA (2006). &EPA ------- |