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Nitrogen Dioxide (NO2) Pollution

Primary National Ambient Air Quality Standards (NAAQS) for Nitrogen Dioxide

Rule Summary

On July 14, 2017, based on a review of the full body of scientific evidence, EPA proposed to retain the current national ambient air quality standards (NAAQS) for oxides of nitrogen (NOx). EPA proposes that the current NAAQS don’t need to be changed because they provide the appropriate public health protection, with an adequate margin of safety, including for older adults, children and people with asthma. The NAAQS for nitrogen oxides are a 1-hour standard at a level of 100 ppb based on the 3-year average of 98th percentile of the yearly distribution of 1-hour daily maximum concentrations, and an annual standard at a level of 53 ppb.

Rule History

07/26/2017 - Review of the National Ambient Air Quality Standards for Oxides of Nitrogen, Proposed Decision

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 Primary National Ambient Air Quality Standards (NAAQS) for Nitrogen Dioxide (NO2)

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