Mr. Karl Brooks 

Regional Administrator 

U.S. EPA, Region VII 

11201 Renner Boulevard 

Lenexa, KS 6621 9 

Dear Mr. Brooks: 

This is in response to your August 19, 2014 letter regarding designations for the 2012 annual fine 

particulate matter (PM2.5) National Ambient Air Quality Standard (NAAQS) of 12 micrograms 

per cubic meter (μg!m\ The letter states the U.S. Environmental Protection Agency (EPA) 

intends to designate the City of St. Louis and St. Louis, St. Charles, Franklin, and Jefferson 

Counties as "unclassifiable" and the rest of the state "attainment/unclassifiable." We are 

concerned that an "unclassifiable" status may leave the St. Louis area open to a future 

nonattainment area designation when the issues with Illinois' PM2.s monitoring data are resolved. 

In our December 10, 2013 submission, we recommended the entire State of Missouri be 

designated "attainment/unclassifiable" for the 2012 annual PM2.s NAAQS. Our recommendation 

considered that all Missouri monitors were in compliance with this standard based on 2010-2012 

ambient monitoring data. It also relied on our technical evaluation of monitoring, emissions, and 

meteorological data demonstrating that Illinois sources, not Missouri sources, were the primary 

contributors to violating monitors located on the Illinois side of the St. Louis area. 

We stand by our recommendation that the entire State of Missouri be designated 

"attainment/unclassifiable" for the 2012 annual PM2.5 NAAQS. All Missouri monitors continue 

to be in compliance of this standard based on 2011-2013 data and annual PM2.5 design values are 

trending downward. Though quality-assurance issues preclude the use of Illinois PM2.5 

monitoring data to determine a violation of the NAAQS, the general conclusions from our 

analysis still stand. Our evaluation of meteorological patterns and general trends data on high 

and low PM2.s days support the conclusion that localized sources in Illinois are the primary 

contributors to the monitors of concern on the Illinois side of the St. Louis area. 

We also have comments on a statement in EPA's Illinois Technical Support Document (TSD) 

indicating that if the Illinois portion of the St. Louis area is determined to be violating the 2012 

PM2.s NAAQS, EPA would likely find the contributing area to be the same as the area 

contributing to violations of the previous 1997 PM2.5 NAAQS of 15 μg/m3

• The 1997 PM2.

5 

standard boundary designation process is not comparable to the current process because one of 

Missouri's monitors in the St. Louis urban core was in violation of that standard at the time. 

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Recycled Paper 
Mr. Karl Brooks 

Page Two 

Consequently, our designation effort for the 1997 standard focused on evaluating Missouri 

sources' contribution to the violating Missouri monitor and recommending an appropriate 

nonattainment area boundary. The Air Program cautions against applying conclusions from the 

previous PM2.5 designation effort to the current process because Missouri does not have any 

monitors violating the 2012 PM2.5 NAAQS. 

We appreciate the valuable assistance EPA Region 7 staff has provided thus far and look forward 

to continuing to work with you and your staff throughout the rest of the process. If you have any 

questions regarding this letter, please contact Ms. Wendy Vit, Air Quality Planning Section 

Chief, Air Pollution Control Program at P.O. Box 176, Jefferson City, MO 65102 or by 

telephone at (573) 751-4817. Thank you for your consideration. 

Sincerely, 

AIR POLLUTION CONTROL PROGRAM 

KM:mlc 

cc: Missouri Air Conservation Commission 

File# 2012-PM-l Annual Designation Recommendation 

Celebrating 40 years of taking care of Missouri's natural resources. 

To learn more about the Missouri Department of Natural Resources visit dnr.mo.gov.