On April 3, 2012, EPA decided to retain the current secondary national ambient air quality standard (NAAQS) for nitrogen dioxide (NO2) and sulfur dioxide (SO2).
This page contains a fact sheet and a presentation describing that action.
For more information, visit the 2012 NO2 and SO2 NAAQS page.You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.
Fact Sheet: Final Revisions to the Secondary National Ambient Air Quality Standards (NAAQS) for Oxides of Nitrogen and Sulfur (PDF)(4 pp, 82 K,
March 20, 2012)
This fact sheet provides an overview of the secondary NAAQS for oxides of nitrogen and sulfur.
July 2011 Proposed Revisions to the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur: Overview (PDF)(14 pp, 461 K,
July 12, 2011)
This presentation provides an overview of the Secondary NAAQS for oxides of nitrogen and sulfur.