The Clean Air Act regulates particulate matter as a criteria pollutant. The U.S. Environmental Protection Agency (EPA) sets National Ambient Air Quality Standards for both fine and course particulate matter (PM). 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 particulate matter 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.
Fine Particulate Matter (PM2.5)
Fine particulate matter (PM2.5) includes particles that are smaller than 2.5 microns in size. The standards for PM2.5 included an annual standard and a 24-hour standard. The annual standard was set in 1997, to 15 micrograms per cubic meter of air (µg/m3). The 24-hour standard was set in 2006, to 35 µg/m3. On Dec. 14, 2012, EPA revised the standard for PM2.5. The 24-hour standard was retained, but the annual standard was lowered from 15 µg/m3 to 12 µg/m3.
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2023 Standard
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2023 Standard Actions
MoDNR Submittal Date MoDNR Action/ Document EPA Date EPA Action/ Document March 23, 2023 MoDNR Comment Letter on Federal Register Action: Reconsideration of the National Ambient Air Quality Standards for Particulate Matter Jan. 27, 2023 Reconsideration of the National Ambient Air Quality Standards for Particulate Matter [88 FR 5558] -
2012 Standard
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Annual PM2.5 Standard = 12 µg/m3
2012 Standard Boundary Recommendations Actions
MoDNR Submittal Date MoDNR Action/ Document EPA Date EPA Action/ Document Oct. 28, 2014 Jan. 1, 2015
Air Quality Designations for the 2012 Primary Annual Fine Particle (PM2.5) National Ambient Air Quality Standards (NAAQS) [80 FR 2206]
Effective: April 15, 2015Dec. 10, 2013 Missouri's Recommendation for the Area Boundary Designations for the 2012 Annual Fine Particulate Matter National Ambient Air Quality Standard Aug. 19, 2014 EPA Response to Recommendations on 2012 Revised Primary Annual Fine Particle (PM2.5) National Ambient Air Quality Standards - 120-day letter for the standard 2012 Standard Infrastructure SIP Actions
MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document Sept. 24, 2015 Oct. 1, 2018
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] 2012 Standard St. Louis Actions
MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document Dec. 10, 2018 July 29, 2019
Approval of Missouri Air Quality Implementation Plans; Redesignation of the Missouri Portion of the St. Louis-St. Charles-Farmington, MO-IL 2012 PM2.5 Unclassifiable Area [84 FR 36742]
Effective: April 15, 2015 -
2006 Standard
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24-hour PM2.5 Standard = 35 µg/m3
2006 Standard Boundary Recommendations Actions
MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document Oct. 2008 Nov. 13, 2009
Air Quality Designations for the 2006 24-Hour Fine Particle (PM2.5) National Ambient Air Quality Standards [74 FR 58688]
Effective: Dec. 14, 2009Dec. 6, 2007 2006 Fine Particle (PM2.5) Boundary Recommendation and Technical Support Document Aug. 18, 2008 EPA Intent to Modify Recommendation for Particulate Matter 2.5 Area Designation as Nonattainment - 120-day letter 2006 Standard Infrastructure Actions
MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document Aug. 27, 2009 June 21, 2013
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1997 Standard
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Annual PM2.5 Standard = 15 µg/m3
1997 Standard Boundary Recommendations Actions
MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document March 8, 2004 1997 Fine Particle (PM2.5) Boundary Recommendation and Technical Support Document
Jan. 5, 2005
Air Quality Designations and Classifications for the Fine Particles (PM2.5) National Ambient Air Quality Standards [70 FR 944]
Effective: April 5, 2005June 29, 2004 EPA Response to 1997 Fine Particle (PM2.5) Boundary Recommendation - 120-day letter 1997 Standard Infrastructure Actions
MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document Feb. 1, 2007 July 22, 2013
Oct. 7, 2011 Federal Implementation Plans: Interstate Transport of Fine Particulate Matter and Ozone and Correction of SIP Approvals [76 FR 48208] July 9, 2007 Approval and Promulgation of Implementation Plans; Missouri; Interstate Transport of Pollution [72 FR 25975] 1997 Standard St. Louis Actions
MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document Nov. 12, 2019 Sept. 30, 2021
Air Plan Approval; Approval of Missouri Air Quality Implementation Plans; Revisions to St. Louis 1997 PM2.5 Maintenance Plan [86 FR 54106]
Effective: Nov. 1, 2021March 27, 2014 Supplement/ Revision to the Redesignation Demonstration and Maintenance Plan for the Missouri Portion of the St. Louis Nonattainment Area for the 1997 Annual Fine Particulate Matter (PM2.5) National Ambient Air Quality Standard Aug. 3, 2018 Aug. 26, 2011 Redesignation Demonstration and Maintenance Plan for the Missouri Portion of the St. Louis Nonattainment Area for the 1997 Annual Fine Particulate Matter (PM2.5) National Ambient Air Quality Standard
Coarse Particulate Matter (PM10)
Course particulate matter (PM10) includes PM2.5 and also coarser particles between 2.5 and 10 microns in size. EPA established the most current standard for PM10 in 2006. The standard is based on the 24-hour average concentrations set at 150 µg/m3.
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2006 Standard
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24-hr PM10 Standard = 150 µg/m3
2006 Standard Carthage Actions
MoDNR Submittal Date MoDNR Action/Document EPA Date EPA Action/Document May 29, 2014 Jan. 28, 2016