The Clean Air Act regulates nitrogen dioxide as a criteria pollutant. The U.S. Environmental Protection Agency (EPA) sets National Ambient Air Quality Standards for nitrogen dioxide (NO2). These standards include both primary standards to protect public health and secondary standards to protect the environment. EPA reviews pollutant standards every five years. Sometimes, a review results in a tightened standard. The standards for NO2 included an annual standard and a 24-hour standard. The annual standard was set in 1971, to 53 parts per billion (ppb). The 24-hour standard was set in 2010, to 100 ppb averaged over one hour (98th percentile of 1-hour daily maximum concentrations, averaged over 3 years). 

The NOstandards below include the state implementation plan elements developed for each of the standards and the relevant documents associated with the boundary designations. If you are looking for a document that is not available on our website, please submit a Open Records/ Sunshine Law Request.

2010 Standard

One-hour NO2 Standard = 100 ppb

2010 Standard Boundary Recommendations Actions

MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document
Aug. 17, 2011 MoDNR Response to EPA 120-Day Letter for the 2010 NO2 Boundary Designations Oct. 31, 2011

All areas of the country designated unclassifiable attainment [No FR Notice]

Dec. 30, 2010

MoDNR Response to EPA Revised 2010 Nitrogen Dioxide Standard Boundary Recommendations

June 28, 2011

EPA Response to MoDNR Revised  2010 Nitrogen Dioxide Standard Boundary Designations - 120-day letter

2010 Standard Infrastructure SIP Actions

MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document
April 26, 2013

Section 110 Infrastructure Requirements for the 2010 Nitrogen Dioxide National Ambient Air Quality Standards

Sept. 24, 2018

Air Plan Approval; Missouri; Regional Haze Plan and Prong 4 (Visibility) for the 2012 PM2.5, 2010 NO2, 2010 SO2, and 2008 Ozone NAAQS [83 FR 48242]

March 22, 2018

Approval of Implementation Plans; State of Missouri; Elements of the Infrastructure State Implementation Plan Requirements for the 2008 Ozone, 2010 Nitrogen Dioxide, 2010 Sulfur Dioxide, and 2012 Fine Particulate Matter National Ambient Air Quality Standards (NAAQS) [83 FR 12496]