Nitrogen Dioxide State Planning

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

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]