• Rule Summary
• Rule History
• Additional Resources

Rule Summary

In 2010, based on its review of the air quality criteria for oxides of nitrogen and the primary NAAQS for oxides of nitrogen as measured by nitrogen dioxide (NO₂), EPA made revisions to the primary NO₂ NAAQS in order to provide requisite protection of public health.

Specifically, EPA established a new 1-hour standard at a level of 100 ppb. This is based on the 3-year average of the 98th percentile of the yearly distribution of 1-hour daily maximum concentrations, to supplement the previously existing annual standard.

EPA also established requirements for an NO₂ monitoring network that now includes both monitors at locations where maximum NO₂ concentrations are expected to occur (such as near major roadways), and monitors sited to measure the area-wide NO₂ concentrations that occur more broadly across communities.

Rule History

02/09/2010 – Final Revision to Nitrogen Dioxide National Ambient Air Quality Standards (NAAQS) & Final Ambient Nitrogen Dioxide Monitoring Requirements Rule

07/15/2009 – Proposed Revision to Nitrogen Dioxide National Ambient Air Quality Standards (NAAQS) & Proposed Ambient Nitrogen Dioxide Monitoring Requirements Rule

Additional Resources

Fact Sheets and Additional Information Regarding the 2010 Revision to the Primary National Ambient Air Quality Standards (NAAQS) for Nitrogen Dioxide (NO₂)

Final Regulatory Impact Analysis (RIA) for the NO₂ National Ambient Air Quality Standards (NAAQS)

Scientific and Technical Documents Supporting the Primary NAAQS for NO₂

Related Rules

Secondary National Ambient Air Quality Standards (NAAQS) for Nitrogen Dioxide (NO₂) and Sulfur Dioxide (SO₂)

Revision to the Near-Road Nitrogen Dioxide Monitoring Requirements

03/14/2013 – Final Rule; Revision to Ambient Nitrogen Dioxide Monitoring Requirements

10/19/2012 – Proposed Revisions to Ambient Nitrogen Dioxide Monitoring Requirements