Carbon Monoxide, or CO
1971 CO Standards - 1-hour standard: 35 ppm, 8-hour standard: 9 ppm
EPA established the CO standards in 1971. Although the CO standards have gone through multiple periodic EPA reviews as required by the Clean Air Act, the standards have not been changed since that time. Therefore, no boundary designation processes for CO have occurred in many years. Additional information is available on EPA's Carbon Monoxide webpage.
- 1971 Standard
Eight-hour CO standard: 9 parts per million, or ppm.
1971 Standard St. Louis Actions Table
MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document April 3, 2014 Oct. 2, 2015
Approved - Second Limited Maintenance Plan
Nitrogen Dioxide, or NO2
Additional information is available on EPA's Nitrogen Dioxide webpage.
- 2010 Standard
One-hour NO2 Standard: 100 ppb
2010 Standard Boundary Recommendations Actions Table
MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document Dec. 30, 2010 Oct. 31, 2011
All areas of the country designated unclassifiable attainment
[No FR Notice]
Aug. 17, 2011 State Response to EPA 120-Day Letter for the 2010 NO2 Boundary Designations EPA 120-Day Letter for the 2010 NO2 Boundary Designations
2010 Standard Infrastructure SIP Actions Table
MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document April 26, 2013 Sept. 24, 2018
Approval of element 110(a)(2)(D)(i) prong 4:
April 23, 2018
Approval of all elements except 110(a)(2)(D)(i) prong 4:
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