1

MISSOURI

Area Designations for the 

2008 Ozone National Ambient Air Quality Standards

The table below identifies the areas and associated counties or parts of counties in Missouri that EPA 

intends to designate as nonattainment for the 2008 ozone national ambient air quality standards (2008

NAAQS). In accordance with section 107(d) of the Clean Air Act, EPA must designate an area (county 

or part of a county) in Missouri as “nonattainment” if it is violating the 2008 ozone NAAQS or if it is 

contributing to a violation of the 2008 ozone NAAQS in a nearby area. The technical analyses 

supporting the boundaries for the individual nonattainment areas are provided below.

Table 1: Intended Nonattainment Areas in Missouri

Area 

Missouri Recommended 

Nonattainment Counties/Areas

EPA’s Intended Nonattainment 

Counties/Areas

St. Louis-St CharlesFarmington, MO-IL

Franklin

Jefferson

St. Louis City

St. Louis County

St. Charles

Franklin

Jefferson

St. Louis City

St. Louis County

St. Charles

St. Louis-St. Charles-Farmington, MO-IL is a multi-state nonattainment area. Table 1 identifies the 

counties in Missouri that EPA intends to designate as part of the nonattainment area. EPA intends to 

designate the remaining counties in Missouri that are not listed in Table 1 as “unclassifiable/attainment” 

for the 2008 ozone NAAQS.

Note that counties in the Illinois portion of the St. Louis-St. Charles-Farmington, MO-IL Combined 

Statistical Area (CSA) are discussed in the ozone designation technical support document for Illinois.

The analysis below provides the basis for the intended nonattainment area boundaries. It relies on 

EPA’s analysis of which monitors are violating the 2008 ozone NAAQS, based on certified air quality 

monitoring data from 2008-2010 and an evaluation of whether nearby areas are contributing to such 

violations. EPA has evaluated contributions from nearby areas based on a weight of evidence analysis 

considering the factors identified below. EPA issued guidance on December 4, 2008 that identified

these factors as ones EPA would consider in determining nonattainment area boundaries and 

recommended that states consider these factors in making their designations recommendations to EPA.

1

 

1. Air quality data (including the design value calculated for each Federal Reference Method 

(FRM) or Federal Equivalent Method (FEM) monitor in the area);

2. Emissions and emissions-related data (including location of sources and population, amount of 

emissions and emissions controls, and urban growth patterns);

3. Meteorology (weather/transport patterns);

4. Geography and topography (mountain ranges or other basin boundaries);

5. Jurisdictional boundaries (e.g., counties, air districts, existing nonattainment areas, Indian 

country, metropolitan planning organizations (MPOs))

 

1 The December 4, 2008 guidance memorandum “Area Designations for the 2008 Revised Ozone National Ambient Air 

Quality Standards” refers to 9 factors. In this technical support document we have grouped the emissions-related factors 

together under the heading of “Emissions and Emissions-Related Data,” which results in 5 categories of factors.
2

Ground-level ozone is not emitted directly into the air, but is created by chemical reactions between 

oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. Because 

NOx and VOC emissions from a broad range of sources over a wide area typically contribute to 

violations of the ozone standards, EPA believes it is important to consider whether there are contributing 

emissions from a broad geographic area. Accordingly, EPA chose to examine the 5 factors with respect 

to the larger of the Combined Statistical Area (CSA) or Core Based Statistical Area (CBSA) associated 

with the violating monitor(s).

2 All data and information used by EPA in this evaluation are the latest 

available to EPA and/or provided to EPA by states or tribes.

In EPA’s designations guidance for the 2008 ozone NAAQS EPA recommended examining 

CSA/CBSAs because certain factors used to establish CSAs and CBSAs are similar to the factors EPA is 

using in this technical analysis to determine if a nearby area is contributing to a violation of the 2008

ozone NAAQS. EPA used the same basic approach in the designation process for the 1997 ozone 

NAAQS. Where a violating monitor is not located in a CSA or CBSA, EPA’s guidance recommended

using the boundary of the county containing the violating monitor as the starting point for considering 

the nonattainment area’s boundary. 

 

2 Lists of CBSAs and CSAs and their geographic components are provided at 

www.census.gov/population/www/metroareas/metrodef.html . The lists are periodically updated by the Office of 

Management and Budget. EPA used the most recent update, based on 2008 population estimates, issued on December 1, 

2009 (OMB Bulletin No. 10-02).
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Technical Analysis for St. Louis-St. Charles-Farmington, MO-IL

Figure 1 is a map of the St. Louis-St. Charles-Farmington, MO-IL intended nonattainment area. The 

map provides other relevant information including the locations and design values of air quality 

monitors, county and other jurisdictional boundaries, St. Louis-St. Charles-Farmington, MO-IL CSA 

boundary, existing nonattainment boundary for 1997 ozone NAAQS, and major transportation arteries.

Figure 1:

For purposes of the 1997 8-hour ozone NAAQS, this area was designated nonattainment. The boundary 

for the nonattainment area for the 1997 ozone NAAQS included the entire counties of Franklin, 

Jefferson, St. Charles, St. Louis, and the City of St. Louis City in Missouri, and Monroe, Jersey, St. 

Clair, and Madison counties in Illinois.

In March 2009, Missouri recommended that the above mentioned counties, plus Lincoln County, in the 

St. Louis area; Cass, Clay, Clinton, Jackson, and Platte counties in the Kansas City area; as well as 

Perry and St. Genevieve counties be designated as “nonattainment.” The state also recommended St. 

Francois and Cape Girardeau counties as “unclassifiable” for the 2008 ozone NAAQS based on air 
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quality data from 2006-2008.

3

In December 2011, Missouri submitted a revised recommendation to 

include the entire counties of Franklin, Jefferson, St. Charles, and St. Louis and the City of St. Louis as 

“nonattainment” for the 2008 ozone NAAQS based on air quality data from 2008-2010. The State 

recommended designating the remaining areas of the State as attainment/unclassifiable. In March 2009,

Illinois recommended that Madison, Monroe and St. Clair Counties be designated as “nonattainment”

for the 2008 ozone NAAQS based on air quality data from 2006-2008.

4

 These recommendations from 

both Missouri and Illinois rely on data from FRM monitors or FEM monitors sited and operated in 

accordance with 40 CFR Part 58. 

After considering these recommendations and based on EPA's technical analysis described below, EPA 

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

St. Louis in Missouri, and the entire counties of Monroe, Madison, and St. Clair in Illinois as

“nonattainment” (as indicated in Table 2 below) for the 2008 ozone NAAQS as the St. Louis-St. 

Charles-Farmington, MO-IL multi-state nonattainment area. 

Table 2. State's Recommended and EPA’s Intended Designated Nonattainment Counties for St. LouisSt. Charles-Farmington, MO-IL Area.

St. Louis-St. CharlesFarmington, MO-ILState-Recommended 

Nonattainment Counties

EPA Intended

Nonattainment Counties

Missouri

Franklin 

Jefferson

St. Charles

St. Louis City

St. Louis County

Franklin

Jefferson

St. Charles

St. Louis City

St. Louis County 

Illinois

Madison

Monroe

St. Clair

Madison

Monroe

St. Clair

Factor Assessment

Factor 1: Air Quality Data 

 

3Missouri submitted its designation recommendations in a March 11, 2009 letter from Mark N. Templeton, Director of the 

Missouri Department of Natural Resources, which included enclosures containing an analysis of data supporting the State’s 

recommendations. Missouri revised its recommendations and MDNR requested EPA to act on the revisions in a letter dated 

December 5, 2011.

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Illinois submitted its designation recommendations in a March 9, 2009 letter from Douglas P. Scott, Director of the Illinois 

Environmental Protection Agency. The state also provided a Technical Support Document dated March 9, 2009, which 

included a nine factor analysis to support the State’s recommendations. 
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For this factor, EPA considered 8-hour ozone design values (in ppm) for air quality monitors in counties 

in the St. Louis-St. Charles-Farmington, MO-IL area based on data for the 2008-2010 period (i.e., the 

2010 design value, or DV), which are the most recent years with fully-certified air quality data. A 

monitor’s DV is the metric or statistic that indicates whether that monitor attains a specified air quality 

standard. The 2008 ozone NAAQS are met when the annual fourth-highest daily maximum 8-hour 

average concentration, averaged over 3 years is 0.075 ppm or less. A DV is only valid if minimum data 

completeness criteria are met. See 40 CFR part 50 Appendix P. Where several monitors are located in a 

county (or a designated nonattainment area or maintenance area), the DV for the county or area is 

determined by the monitor with the highest level.

NOTE: Eligible monitors for providing design value data generally include State and Local Air 

Monitoring Stations (SLAMS) at population-oriented locations with an FRM monitor. All data from 

Special Purpose Monitors (SPM) using an FRM are eligible for comparison to the relevant NAAQS, 

subject to the requirements given in the October 17, 2006 Revision to Ambient Air Monitoring 

Regulations (71 FR 61236). All monitors used to provide data must meet the monitor siting and 

eligibility requirements given in 71 FR 61236 to 61328 in order to be acceptable for comparison to the 

2008 ozone NAAQS for designation purposes.

The 2010 DVs for the ozone NAAQS, where available, for counties in the St. Louis-St. CharlesFarmington, MO-IL CSA are shown in Table 3. 

Table 3. Air Quality Data.

County State Recommended 

Nonattainment?

2008-2010 Design Value

(ppb)

Missouri:

Franklin, MO Yes

Jefferson, MO Yes 72

Lincoln, MO No 72

St. Charles, MO Yes 77

St. Francois, MO No

St. Louis, MO Yes 71

St. Louis City, MO Yes 69

Warren, MO No

Washington, MO No

Illinois:

Bond, IL No

Calhoun, IL No

Clinton, IL No

Jersey, IL No 69

Macoupin, IL No 66

Madison, IL Yes 72

Monroe, IL Yes

St. Clair, IL Yes 68

St. Charles County in Missouri shows a violation of the 2008 ozone NAAQS, therefore this is included

in the nonattainment area. A county (or partial county) must also be designated nonattainment if it 

contributes to a violation in a nearby area. Each county without a violating monitor that is located near a 

county with a violating monitor has been evaluated based on the weight of evidence of the five factors to 

determine whether it contributes to the nearby violation. 
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Factor 2: Emissions and Emissions-Related Data

EPA evaluated emissions of ozone precursors (NOx and VOC) and other emissions-related data that 

provide information on areas contributing to violating monitors.

Emissions Data

EPA evaluated county-level emission data for NOx and VOC derived from the 2008 National Emissions 

Inventory (NEI), version 1.5. This is the most recently available NEI. (See

http://www.epa.gov/ttn/chief/net/2008inventory.html) Significant emissions levels in a nearby area 

indicate the potential for the area to contribute to observed violations. EPA will also consider any 

additional information we receive on changes to emissions levels that are not reflected in recent 

inventories. These changes include emissions reductions due to permanent and enforceable emissions 

controls that will be in place before final designations are issued and emissions increases due to new 

sources.

Table 4 shows emissions of NOx and VOC (given in tons per year) for violating and potentially 

contributing counties in the St. Louis-St. Charles-Farmington, MO-IL CSA. 

Table 4. Total 2008 NOx and VOC Emissions.

County State Recommended

Nonattainment? NOx (tpy) VOC (tpy)

Missouri:

Franklin, MO Yes 14,094 4,939

Jefferson, MO Yes 11,769 6,729

Lincoln, MO No 1,855 2,081

St. Charles, MO Yes 15,894 11,652

St. Francois, MO No 2,030 2,349

St. Louis, MO Yes 36,455 41,894

St. Louis City, MO Yes 17,576 14,027

Warren, MO No 1,749 2,064

Washington No 678 862

Missouri Total: 102,099 86,596

Illinois

Bond, IL No 1,422 1,181

Calhoun, IL No 607 1,057

Clinton, IL No 4,409 2,515

Jersey, IL No 1,125 1,166

Macoupin, IL No 2,286 2,147

Madison, IL Yes 23,109 12,351

Monroe, IL Yes 2,410 1,551

St. Clair, IL Yes 10,804 8,719

Illinois total: 46,173 30,687

Areawide: 148,272 117,284
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The emission data in Table 4 indicate that for Missouri, the highest NOx and VOC emissions reside in 

St. Louis County and the City of St. Louis. In 2008 these two areas accounted for 53% and 65% of NOx

and VOC emissions respectively for the Missouri portion of the area. In addition, Franklin and Jefferson 

Counties also have comparatively high NOx emissions (behind St. Louis and St. Charles Counties and 

the City of St. Louis) and form a contiguous area with the three top emitting areas. Together, the City of 

St. Louis, Franklin, Jefferson, and St. Louis Counties make up 78% of both NOx and VOC emissions in 

the Missouri portion of the area, and 54% of the NOx emissions and 58% of the VOC emissions for the 

entire St. Louis-St. Charles-Farmington, MO-IL CSA. 

The NOx and VOC emissions are relatively low in Warren, Washington, and Lincoln counties. Together 

in 2008 these counties account for 4% of NOx and 6% of VOC in the Missouri portion of the area. 

Note that the relative emissions levels in the Illinois portion of the St. Louis-St. Charles-Farmington, 

MO-IL CSA are discussed in the ozone designation technical support document for Illinois. 

Population density and degree of urbanization

EPA evaluated the population and vehicle use characteristics and trends of the area as indicators of the 

probable location and magnitude of non-point source emissions. These include ozone-creating 

emissions from on-road and off-road vehicles and engines, consumer products, residential fuel 

combustion, and consumer services. Areas of dense population or commercial development are an 

indicator of area source and mobile source NOx and VOC emissions that may contribute to ozone 

formation. Rapid population or Vehicle Miles Traveled (VMT) growth (see below) in a county on the 

urban perimeter signifies increasing integration with the core urban area, and indicates that the 

associated area source and mobile source emissions may be appropriate to include in the nonattainment 

area. Table 5 shows the population, population density, and population growth information for each 

county in the area.

Table 5. Population and Growth.

County State 

Recommended 

Nonattainment?

2010 

Population

 2010

 Population

 Density

(1000 pop/sq mi)

 Absolute

 change

in population

(2000-2010)

Population 

% change

(2000-

2010)

Missouri:

Franklin, MO

Yes 

101,492 

 

0.11 

 

7,434 +8% 

Jefferson, MO Yes 

218,733 

 

0.33 

 

19,995 +10% 

Lincoln, MO No 

52,566 

 

0.08 

 

13,310 +34% 

St. Charles, MO Yes 

360,485 

 

0.61 

 

74,322 +26% 

St. Francois, MO No 

65,359 

 

0.14 

 

9,615 +17% 

St. Louis, MO Yes 

998,954 

 

1.91 

 

17,376 -2% 

St. Louis City, MO Yes 

319,294 

 

4.83 

 

27,570 -8% 

Warren, MO No 

32,513 

 

0.07 

 

7,793 +32% 

Washington No 

25,195 0.03 1,785 +8%
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Missouri total: 

2,174,591 0.43

 

89,308 +4%

Illinois:

Bond, IL No 

17,768 0.05

 

118 +1% 

Calhoun, IL No 

5,089 0.02

 

(1) 0% 

Clinton, IL No 

37,762 0.08

 

2,233 +6% 

Jersey, IL No 

22,985 0.06

 

1,330 +6% 

Macoupin, IL No 

47,765 0.06

 

(1,224) -2% 

Madison, IL Yes 

269,282 0.36

 

10,165 +4% 

Monroe, IL Yes 

32,957 0.08

 

5,193 +19% 

St. Clair, IL Yes 

270,056 0.40

 

13,852 +5% 

Illinois total: 

703,664 0.17

 

31,666 +5%

Areawide: 2,878,255 0.31 120,974 +4%

Sources: U.S. Census Bureau population estimates for 2010 as of August 4, 2011 

(http://factfinder2.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=DEC_10_PL_GCTPL2.STO5&

prodType=table) and U.S. Census Bureau GIS files for the county boundaries

In the Missouri portion of the St. Louis-St. Charles-Farmington, MO-IL CSA, St. Louis and St. Charles 

counties along with the City of St. Louis have comparatively high population and high population 

density. This also correlates to those three counties having the highest amount of NOx and VOC 

emissions in the area. Warren, Washington, and St. Francois Counties have relatively low population, 

population density, and lowest absolute change in population. Lincoln County has relatively low 

population for the area, as well as one of the lowest population densities (behind Warren and 

Washington Counties) among the Missouri Counties in the CSA. 

Note that the ozone designation technical support document for Illinois addresses the population-related 

emission contributions from the Illinois portion of the St. Louis-St. Charles-Farmington, MO-IL CSA.
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Traffic and commuting patterns

EPA evaluated the commuting patterns of residents in the area, as well as the total VMT for each 

county. In combination with the population/population density data and the location of main 

transportation arteries (see Figure 1 above), this information helps identify the probable location of nonpoint source emissions. A county with high VMT and/or a high number of commuters is generally an 

integral part of an urban area and indicates the presence of motor vehicle emissions that may contribute 

to ozone formation. Rapid population or VMT growth in a county on the urban perimeter signifies 

increasing integration with the core urban area, and indicates that the associated area source and mobile 

source emissions may be appropriate to include in the nonattainment area. 

Table 6 shows traffic and commuting pattern data, including total 2008 VMT for each county, number 

of commuters in each county who drive to another county within the area, and the percent of total 

commuters in each county who commute to other counties within the area.

Table 6. Traffic and Commuting Patterns.

County

State 

Recommended 

Nonattainment?

2008 VMT*

(million miles)

Number Commuting 

to or within any 

violating counties**

Percent Commuting 

to or within any 

violating counties**

Missouri:

Franklin, MO Yes 1,637 776 2%

Jefferson, MO Yes 1,885 1,337 1%

Lincoln, MO No 495 5,529 30%

St. Charles, MO Yes 2,728 70,282 47%

St. Francois, MO No 548 92 0%

St. Louis, MO Yes 11,925 13,513 3%

St. Louis City, MO Yes 3,450 1,502 1%

Warren, MO No 525 2,967 25%

Washington No 220 27 0%

Missouri total: 23,414 96,025 10%

Illinois:

 Bond County No 284 20 0%

 Calhoun County No 40 109 5%

 Clinton County No 389 49 0%

 Jersey County No 192 125 1%

 Macoupin County No 415 36 0%

 Madison County Yes 2,839 1,126 1%

 Monroe County Yes 361 84 1%

 St. Clair County Yes 2,666 729 1%

Illinois total: 7,186 2,278 1%

Areawide: 30,599 98,303 8%

* MOBILE model VMTs are those inputs into the NEI version 1.5. 

** U.S. Census Bureau estimates for 2000 County-to-County Worker Flow 

http://www.census.gov/hhes/commuting/data/commuting.html.

For Missouri, the VMT data show that VMT levels in St. Louis City, St. Louis County, and St. Charles 

County are significantly higher than those in other Missouri counties in the St. Louis-St. Charles-
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Farmington, MO-IL CSA. Cumulatively, the VMT in these counties are a significant portion of the total 

VMT for the St. Louis-St. Charles-Farmington, MO-IL CSA.

Note that the ozone designation technical support document for Illinois addresses the traffic and 

commuting patterns for the Illinois portion of the St. Louis-St. Charles-Farmington, MO-IL CSA.

Factor 3: Meteorology (weather/transport patterns)

EPA evaluated any available meteorological data to help determine how meteorological conditions, such 

as weather, transport patterns and stagnation conditions, would affect the fate and transport of precursor 

emissions contributing to ozone formation. EPA examined the frequency distribution of wind directions 

during the summer by averaging National Weather Service direction-sorted wind directions for each 

county for a 30 year period. To apply the results of this data analysis to the St. Louis-St. CharlesFarmington, MO-IL CSA, we have considered the wind direction frequencies during the summer 

months (June-August) for St. Charles County in Missouri, the only county with a recorded violation of 

the 2008 ozone NAAQS (see Table 2). The table below shows the summertime 30-year averaged 

percentages of wind directions for St. Charles County in Missouri.

Averaged Summertime Wind Direction Percentages for St. Charles County, MO

Wind Direction Percentage

North-Northeast 9.82%

East-Northeast 7.24%

East-Southeast 13.66%

South-Southeast 14.41%

South-Southwest 20.01%

West-Southwest 14.64%

West-Northwest 12.84%

North-Northwest 7.39%

The table indicates that winds from the south-southwest may be slightly more prevalent than winds from 

other directions during the summertime, and there is a southerly component 62.72% of the time. This 

means that the locations of Franklin, St. Louis and Jefferson counties, as well as St. Louis city, are

upwind when the southerly component occurs.

Factor 4: Geography/topography (mountain ranges or other air basin boundaries)

The geography/topography analysis evaluates the physical features of the land that might affect the 

airshed and, therefore, the distribution of ozone over the area.

The St. Louis-St. Charles-Farmington, MO-IL area does not have any geographical or topographical 

barriers significantly limiting air pollution transport within its air shed. Therefore, this factor did not 

play a significant role in this evaluation.
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Factor 5: Jurisdictional boundaries

Once the general areas to be included in the nonattainment area were determined, EPA considered

existing jurisdictional boundaries for the purposes of providing a clearly defined legal boundary and 

carrying out the air quality planning and enforcement functions for nonattainment areas. Examples of 

jurisdictional boundaries include existing/prior nonattainment areas for ozone or other urban-scale 

pollutants, counties, air districts, townships, metropolitan planning organizations, state lines, 

Reservations, urban growth boundary, etc. Where existing jurisdictional boundaries are not adequate to 

describe the nonattainment area, other clearly defined and permanent landmarks or geographic 

coordinates were considered.

The St. Louis, MO-IL area has previously established nonattainment boundaries associated with the 1-

hour and the 1997 8-hour ozone NAAQS. The Missouri portion of the St. Louis-St. CharlesFarmington, MO-IL CSA that EPA is intending to designate as nonattainment for the 2008 ozone 

NAAQS is the same area that EPA designated as nonattainment under the 1-hour NAAQS, as well as 

what was recommended by the state of Missouri and designated nonattainment for the 1997 8-hour 

ozone NAAQS. Under the 1997 8-hour ozone NAAQS for the Illinois portion of the St. Louis-St. 

Charles-Farmington, MO-IL CSA, Jersey County, IL was also included in the nonattainment area due to 

a monitored violation of the standard in that county. The state of Illinois has recommended designating 

Jersey County, IL as attainment for the 2008 ozone NAAQS. The monitor in Jersey County, IL is 

currently monitoring attainment and, as provided in the TSD for Illinois, we do not believe Jersey 

County is contributing to nonattainment at the violating monitors in the area. Thus, we do not intend to 

include Jersey County is the designated nonattainment area. 

Conclusion

Based on the assessment of factors described above, EPA has preliminarily concluded that the following 

Missouri areas meet the CAA criteria for inclusion in the St. Louis-St. Charles-Farmington, MO-IL

nonattainment area because they are either violating the 2008 ozone NAAQS or contributing to a 

violation in a nearby area: Franklin County, Jefferson County, St. Charles County, St. Louis City, and 

St. Louis County. This is consistent with the recommendation submitted by Missouri. These are the 

same Missouri counties that were included in the St. Louis, MO-IL nonattainment area for the 1-hour 

ozone NAAQS as well as for the 1997 8-hour ozone NAAQS. One air quality monitor in the Missouri 

counties (St. Charles) indicated a violation of the 2008 ozone NAAQS based on 2010 design values, 

therefore this county is included in the nonattainment area. Franklin County, Jefferson County , St. 

Louis City, and St. Louis County are nearby counties that do not have violating monitors, but EPA has 

concluded that these areas contribute to the ozone concentrations in violation of the 2008 ozone NAAQS

in St. Charles County. This conclusion is based in part on relatively high NOx and VOC emissions and 

relatively high VMT in those counties. Based on 2008 data, St. Louis County, St. Louis City, Franklin 

County, and Jefferson County have the first, second, fourth, and fifth highest NOx emissions 

respectively in the St. Louis-St. Charles-Farmington, MO-IL CSA. These counties also have among the 

highest VOC emissions in the St. Louis-St. Charles-Farmington, MO-IL CSA. St. Louis County and St. 

Louis City have the highest 2008 VMT, and Franklin and Jefferson has the fourth and fifth highest 2008 

VMT in the St. Louis-St. Charles-Farmington, MO-IL CSA.