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 NO2 standards 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
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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 Sept. 24, 2018 March 22, 2018