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.

St. Louis

1971 Standard St. Louis Actions Table

MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document
April 3, 2014

St. Louis 1971 Carbon Monoxide Standard Limited Maintenance Plan

Appendix A

Appendix B

 

Oct. 2, 2015

Approved - Second Limited Maintenance Plan

[80 FR  59611]

Nitrogen Dioxide, or NO2

Additional information is available on EPA's Nitrogen Dioxide webpage.

2010 Standard

One-hour NO2 Standard: 100 ppb

Boundary Recommendations

2010 Standard Boundary Recommendations Actions Table

MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document
Dec. 30, 2010

2010 NO2 Standard Boundary Recommendations

Attachment 1

Attachment 2

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

Infrastructure SIP

2010 Standard Infrastructure SIP Actions Table

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

Infrastructure Elements for the 2010 NO2 Standard

Sept. 24, 2018

Approval of element 110(a)(2)(D)(i) prong 4:

[83 FR 48242]

April 23, 2018

Approval of all elements except 110(a)(2)(D)(i) prong 4:

[83 FR 12496]

Related Links

Carbon Monoxide Pollutants and Sources

Nitrogen Dioxide Pollutants and Sources

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