(217) 785-4140

(217) 782-9143 (TDD)

March 9, 2009

Mr. Bharat Mathur, Acting Regional Administrator

Office of the Regional Administrator

USEPA Region 5, R19J

77 West Jackson Boulevard

Chicago, Illinois 60604-3507

Dear Mr. Mathur:

On behalf of Governor Quinn, and pursuant to the U.S. Environmental Protection Agency’s 

revision to the National Ambient Air Quality Standards (NAAQS) for ozone dated March 12, 

2008, I am submitting our recommendations for attainment and nonattainment designations for 

the State of Illinois. Included with Illinois’ recommendations is a supporting document prepared 

by the Illinois Environmental Protection Agency (Illinois EPA). The Illinois EPA will also 

provide this document to your staff in electronic format to facilitate your timely review. 

Specifically, the following designations are recommended for Illinois:

Cook Nonattainment Chicago

DuPage Nonattainment Chicago

Kane Nonattainment Chicago

Lake Nonattainment Chicago

Will Nonattainment Chicago

McHenry Nonattainment Chicago

Kendall:

 Oswego Township

 All Other Townships

Nonattainment

Attainment

Chicago

Grundy:

 Aux Sable Township

 Goose Lake Township

 All Other Townships

Nonattainment

Nonattainment

Attainment

Chicago

Chicago

Madison

 

Nonattainment Metro-East

Monroe Nonattainment Metro-East

St. Clair Nonattainment Metro-East

All Other Counties Attainment
We are recommending that portions of the Chicago and Metro-East metropolitan areas be designated as 

nonattainment for the revised 8-hour ozone NAAQS. As violations of the revised ozone standard have 

been measured in these areas during 2006-2008, designating them as nonattainment is appropriate. The 

remainder of Illinois is attaining the revised ozone standard and should, therefore, be designated as 

attainment. 

The recommended nonattainment boundaries are the same as the boundaries established pursuant to the 

1997 revisions of the ozone NAAQS, with the exception of Jersey County. We are recommending that 

Jersey County, which is located in the Metro-East area in southwestern Illinois, be designated as 

attainment for the revised ozone standard even though it is currently designated nonattainment for the 

1997 version of the standard. Jersey County is rural, with virtually no emission sources, and does not 

contribute to nearby nonattainment areas. Jersey County was included in the nonattainment area 

established in 2004 because violations of that standard were measured in 2001-2003 at Illinois EPA’s

monitoring station located in Jerseyville. Based on 2006-2008 data, the monitoring station located in 

Jerseyville is attaining not just the level of the standard established in 1997, but it is attaining the level of 

the revised standard as well.

If there are any questions, please feel free to contact me or Laurel L. Kroack, Chief of the Bureau 

of Air at Illinois EPA.

Very truly yours,

Douglas P. Scott

Director

cc: Cheryl Newton, Acting Chief

Air and Radiation Division

U.S. Environmental Protection Agency, Region 5

Attachment
Technical Support Document

for

Recommended Nonattainment Boundaries in Illinois 

for the

8-hour Ozone National Ambient Air Quality Standard

AQPSTR 09-01

March 9, 2009

Illinois Environmental Protection Agency

Division of Air Pollution Control

1021 North Grand Avenue East

P.O. Box 19276

Springfield, IL 62794-9276
2

Table of Contents

Tables................................................................................................ 4

Figures............................................................................................... 5

Introduction......................................................................................... 6

Federal Guidance................................................................................... 7

Nine Factor Analysis.............................................................................. 9

Air Quality Data.................................................................................... 9

Emissions Data..................................................................................... 12

Population Density and Urbanization........................................................ .... 14

Growth Rates and Patterns........................................................................ 17

Traffic and Commuting Patterns................................................................. 18

Topography.......................................................................................... 20

Jurisdictional Boundaries.......................................................................... 21

Meteorology......................................................................................... 21

Level of Control of Emission Sources........................................................... 22

Recommendations.................................................................................. 24

 Chicago Metropolitan Area ............................................................................. 24

Cook County................................................................................ 24

Lake County................................................................................ 25

DuPage and Will Counties............................................................... 25

McHenry and Kane Counties............................................................ 25

DeKalb and Kankakee Counties........................................................ 26

Grundy and Kendall Counties.......................................................... 26

 St. Louis Metropolitan Area.......................................................................... 26

Madison County........................................................................... 26

St. Clair County........................................................................... 27

Monroe County............................................................................ 27

Jersey County.............................................................................. 27

Clinton County............................................................................. 28
3

Randolph County......................................................................... 28

Macoupin, Bond and Calhoun Counties.............................................. 28

Montgomery County...................................................................... 29

Washington County...................................................................... 29

Remainder of Illinois.............................................................................. 30
4

Tables

Table 1 Counties Included in the Chicago CSA and St. Louis MSA.................... 8

Table 2 2006 – 2008 8-Hour Ozone Design Values in Illinois (ppb).................. 11

Table 3 Population and Population Density Estimates by County

Chicago CSA (Illinois Counties Only)

 St. Louis MSA and Adjacent Counties (Illinois Counties Only)......... 15

Table 4 Average Daily Vehicles Miles Traveled for Selected Counties

from Illinois Travel Statistics 2007........................................... 18

Table 5 Recommended Attainment/Nonattainment Designations in Illinois

for the 8-Hour Ozone National Ambient Air Quality Standard........... 31

Table 6: 8-Hour Ozone Boundary Recommendations Nine Factor Documentation... 32
5

Figures

Figure 1 Proposed Illinois 8-Hour Ozone Nonattainment Areas within CSA/MSA

Figure 2 Illinois 8-hour Ozone Design Values 2006-2008

Figure 3 2006-2008 Lake Michigan 8-Hour Ozone Design Values

Figure 4 2006-2008 St. Louis, MO 8-Hour Ozone Design Values

Figure 5a 2005 NOx Emissions by County for the Chicago CSA (Tons/Day)

Figure 5b 2005 VOC Emissions by County for the Chicago CSA (Tons/Day)

Figure 6a 2005 NOx Emissions by County for St. Louis MSA (Tons/Day)

Figure 6b 2005 VOC Emissions by County for St. Louis MSA (Tons/Day)

Figure 7a Major NOx Point Sources – 2005 Emissions for Chicago CSA 

Figure 7b Major VOC Point Sources - 2005 Emissions for Chicago CSA

Figure 8a Major NOx Point Sources – 2005 Emissions for St. Louis MSA

Figure 8b Major VOC Point Sources – 2005 Emissions for St. Louis MSA

Figure 9 Population Density (2007) by Census Tract in the Chicago CSA

Figure 10 Population Density (2007) by Census Tract in the St. Louis MSA

Figure 11 Urban Areas within Chicago-Naperville-Michigan City, IL-IN-WI Combined 

Statistical Area (CSA)

Figure 12 Urban Areas within St. Louis MO-IL MSA and Adjacent Counties

Figure 13 Land Cover in the Chicago-Naperville-Michigan City IL-IN-WI CSA (Illinois 

Part)

Figure 14 Land Cover in the St. Louis MO-IL MSA and Adjacent Counties (Illinois Part)

Figure 15 2000-2007 Population Change by County Chicago CSA (Illinois Part)

Figure 16 2000-2007 Population Change by County St. Louis MSA (Illinois Part)

Figure 17 Population Projections Total Population by County Change from 2000-2030

Figure 18 Occupational Employment Projections by County - Change from 2004 - 2014

Figure 19 2007 Average Daily Vehicle Miles Traveled (ADVMT) in the Chicago Area

Figure 20 2007 Average Daily Vehicle Miles Traveled (ADVMT) in the St. Louis Area

Figure 21 Average Daily VMT in the Chicago NAA, 1990 – 2007

Figure 22 Average Daily VMT in the Metro-East NAA, 1990 – 2007

Figure 23 Where People Reside and Counties Where they Journey to Work Chicago CSA 

Counties

Figure 24 Where People Reside and Counties Where they Journey to Work St. Louis MSA 

and Adjacent Counties

Figure 25 Topography

Figure 26 Chicago Area Pollution Rose 2006 – 2008 (All Sites)

Figure 27 Metro-East Pollution Rose 2006 – 2008 (All Sites)

Figure 28 Proposed 8-Hour Ozone Nonattainment Areas
6

Introduction

On March 12, 2008, U.S. Environmental Protection Agency (U.S. EPA) revised the ozone

National Ambient Air Quality Standard (NAAQS) in response to numerous studies which link 

the health effects associated with ozone exposure to increases in mortality, as well as 

cardiovascular and respiratory health effects. The primary ozone standard was strengthened 

from 0.08 parts per million (ppm), set in 1997 to a level of 0.075 ppm (73 FR16436; March 27, 

2008). U.S. EPA also strengthened the secondary ozone standard to provide increased 

protection against adverse public welfare effects including impacts on vegetation. This standard 

is identical to the primary standard (0.075 ppm). Following the promulgation of a new or revised 

air quality standard, the Clean Air Act (CAA) requires the Governor to recommend initial 

designations of the attainment status for all areas of the State. Areas can be classified as 

nonattainment (does not meet, or contributes to a nearby area that does not meet the NAAQS), 

attainment (meets the NAAQS), or unclassifiable (cannot be classified based on available data). 

Illinois is, therefore, required to provide recommendations for attainment/nonattainment area 

boundaries for the new 8-hour ozone standard. The U.S. EPA will act on the State’s 

recommendations by either affirming and promulgating the recommended designation 

boundaries, or by promulgating new designations.

This report provides the basis for recommendations by the Illinois Environmental Protection 

Agency (IEPA) for attainment/nonattainment designation boundaries for all areas in the State of 

Illinois for the 8-hour ozone standard. Based on the most recent three years of ambient 

monitoring data (2006-2008), only two counties in Illinois are currently violating the 8-hour 

ozone NAAQS, Cook and Madison counties. Based on an analysis of the factors contained in 

federal guidance, the IEPA is recommending that portions of the Chicago and Metro-East 

metropolitan areas be designated as nonattainment for the 8-hour ozone standard. The 

recommended boundaries also reflect U.S. EPA guidance “to show that: 1) violations are not 

occurring in the excluded portions of the recommended area and 2) the excluded portions do not 

contain emission sources that contribute to the observed violations.” The remaining areas of 

Illinois should be classified as attainment areas for the ozone standard (Figure 1). 
7

Federal Guidance

IEPA initially relied on guidance memorandums issued by U.S. EPA on March 28, 2000 and 

April 1, 2003 for developing this recommendation for establishing the geographic boundaries of 

nonattainment areas (NAA) for the 8-hour ozone standard. In these guidance documents, U.S. 

EPA recommended that areas with air quality data showing violations of the 8-hour NAAQS, 

and nearby areas that cause or contribute to NAAQS violations, be designated nonattainment. 

Due to the pervasive nature of ground level ozone, and transport of ozone and its precursors over 

large geographic areas, U.S. EPA also recommends that Metropolitan Statistical Areas (MSAs),

as well as Core Based Statistical Areas (CBSAs) or Combined Statistical Areas (CSAs), as 

defined by the Office of Management and Budget (OMB), associated with the violating 

monitor(s) serve as the starting point or “presumptive” boundary of 8-hour ozone NAAQS. U.S. 

EPA published updated guidance on December 4, 2008. This guidance follows the same 

conceptual approach as the March 2000 and April 2003 guidance in that it recommends 

presumptive boundaries based on CSA and CBSA defined statistical areas.

The proposed ozone nonattainment area boundaries are shown in Figure 2 and are included 

within the boundaries of the Chicago-Naperville-Michigan City, IL-IN-WI Combined Statistical 

Area (Chicago CSA) and St. Louis MO-IL Metropolitan Statistical Area (St. Louis MSA). For 

the purpose of this analysis, the St. Louis MSA counties in Illinois are consistent with the CSA 

boundaries included in the St. Louis, St. Charles-Farmington, MO-IL CSA. A listing of the 

counties comprising the Chicago CSA and the St. Louis, St. Charles-Farmington, MO-IL CSA 

are included in Table 1. Of these statistical areas, only those counties in Illinois are represented 

as part of this analysis.
8

TABLE 1

COUNTIES INCLUDED IN THE

CHICAGO CSA AND ST. LOUIS MSA*

Chicago-Naperville-Michigan City (IL-IN-WI) 

Combined Statistical Area

St. Louis, St. Charles-Farmington,

MO-IL CSA

Cook County, IL Bond County, IL

DuPage County, IL Calhoun County, IL

Lake County, IL Clinton County, IL

Kane County, IL Jersey County, IL

Will County, IL Macoupin County, IL

DeKalb County, IL Madison County, IL

McHenry County, IL Monroe County, IL

Kankakee County, IL St. Clair County, IL

Kendall County, IL

Grundy County, IL

Crawford County

(Sullivan City), MO

Lake County, IN Jefferson County, MO

Porter County, IN Lincoln County, MO

Jasper County, IN St. Charles County, MO

Newton County, IN St. Louis County, MO

LaPorte County, IN Warren County, MO

Kenosha County, WI Washington County, MO

St. Louis City, MO

Franklin County, MO

St. Francois County, MO

*Bold Face County Names represent Counties in St. Louis, MO-IL MSA

Metropolitan areas defined by U.S. Office of Management and Budget, November 20, 2007

Website: http://www.census.gov/population/www/metroareas/metrodef.html

States may request nonattainment area boundaries that are smaller than the existing CSA or 

CBSA (MSA) boundaries where counties, or portions of counties are rural and do not contribute 

to nonattainment based on nine factors. The nine factors are listed below. States may also 

request nonattainment area boundaries that are larger than the current CSA/CBSA or MSA to 

include adjacent counties when those counties contain emission sources, population, growth, 

commuting patterns and other factors that may contribute to the nonattainment problem. The 

IEPA’s analysis of each of the nine factors is provided in the following sections of this report. 
9

Nine Factor Analysis

U.S. EPA recommends that States and Tribes consider the following nine factors in assessing 

whether to include an area in the designated nonattainment area boundary:

Air quality data

Emission data

Population density and degree of urbanization 

Growth rates and patterns

Traffic and commuting patterns

Geography/topography

Jurisdictional Boundaries

Meteorology (weather/transport patterns)

Level of control of emission sources

Air Quality Data

The 8-hour ozone design values (i.e., the average of the fourth highest values from each of three 

consecutive years of data at a given ambient monitor) derived from ozone measurements 

collected from IEPA’s ambient air monitoring network from the most recent 3-year period of 

record (2006-2008) are summarized in Table 2 and Figure 2. As shown in Table 2 and Figure 2, 

IEPA’s monitoring data indicate that violations of the 8-hour ozone standard have been 

measured in both the Chicago and Metro-East metropolitan areas. The rest of Illinois currently 

meets the 8-hour standard, although occasional exceedances have been recorded at almost all 

monitoring sites statewide due to the pervasiveness of ozone transport. Violations of the 8-hour 

standard within the Chicago and Metro-East areas have been measured at only a few locations. 

In the Chicago area, measured design values from the 2006-2008 period exceed the NAAQS at 

only one monitoring station located in Cook County. In the Metro-East area, design values 

exceeding the NAAQS have been measured in Madison County during this 3-year period. 

Ozone air quality data collected in Illinois, therefore, indicate that it is appropriate to designate at 

least portions of the Chicago and Metro-East metropolitan areas as nonattainment areas for the 
10

8-hour ozone standard. The remaining portions of Illinois should be designated attainment for 

the 8-hour ozone standard. 

Figures 3 and 4 depict ozone design values for 2006-2008 in the Lake Michigan and St. Louis 

areas, respectively. In both areas, ozone design values of greater magnitude and broader spatial 

extent occur in neighboring states than are observed in Illinois. 
11

Table 2

2006-2008 

8-Hour Ozone Design Values in Illinois (ppb)

4th High 2006-2008

8-Hour Values 8-hr

AQCR County Site Address 2006 2007 2008 Average

Chicago Metropolitan Area

67 Cook Alsip 4500 W 123rd St 78 85 66 76

67 Cook Chicago-ComEd 7801 Lawndale 75 80 66 73

67 Cook Chicago-Jardine 1000 E. Ohio 65 75 63 67

67 Cook Chicago-SWFP 3300 E. Cheltenham 75 82 67 74

67 Cook Chicago-Taft 6545 W. Hurlburt 77 79 64 73

67 Cook Chicago-University 5720 S. Ellis 70 79 63 70

67 Cook Cicero 1830 S. 51st Ave 60 68 60 62

67 Cook Des Plaines 9511 W. Harrison St. 65 78 57 66

67 Cook Evanston 531 Lincoln 72 80 58 70

67 Cook Lemont 729 Houston 70 85 71 75

67 Cook Northbrook 750 Dundee Rd 68 76 65 69

67 DuPage Lisle Morton Arboretum 62 72 57 63

67 Kane Elgin 665 Dundee 62 75 61 66

67 Lake Waukegan Golf & Jackson 71 81 63 71

67 Lake Zion Camp Logan 68 80 69 72

67 McHenry Cary 1st St. & Three Oaks 57 74 65 65

67 Will Braidwood 36400 S. Essex Rd 68 71 60 66

Metro-East 

70 Madison Alton 409 Main St. 79 81 68 76

70 Madison Maryville 200 W. Division 77 87 70 78

70 Madison Wood River 54 N. Walcott 77 86 67 76

70 Randolph Houston Hickory Grove & Fallview 72 79 65 72

70 St. Clair East St. Louis 13th & Tudor 77 77 64 72

75 Jersey Jerseyville Liberty St. 75 75 69 73

Rest of Illinois

65 Peoria Peoria Hurlburt & Mac Arthur 67 74 60 67

65 Peoria Peoria Hts 508 E. Glen 70 81 67 72

66 McLean Normal Main & Gregory 72 75 67 71

66 Champaign Champaign 606 E. Grove 64 71 60 65

69 Rock Island Rock Island 32 Rodman Ave. 70 71 58 66

73 Winnebago Loves Park 1405 Maple 63 73 60 65

74 Effingham Effingham Route 45 South 67 78 63 69

74 Hamilton Knight Prairie State Route 14 66 76 66 69

75 Adams Quincy 732 Hampshire 71 75 65 70

75 Macon Decatur 2200 N 22nd St. 71 77 85 71

75 Macoupin Nilwood Heaton & DuBois 70 75 65 70

75 Sangamon Springfield 2875 N. Dirksen 66 72 59 65

Note: The Quincy ozone monitor was moved in 2007. Data for 2006 is from the old AIRS site 170010006; data for 2007 and 

2008 was collected at the new AIRS site 170010007. 
12

Emissions Data

U.S. EPA recommends that proposed nonattainment designations for the new 8-hour NAAQS 

reflect not only the areas of measured violations, but also the nearby areas that contribute to 

measured violations. Ozone is a secondary pollutant formed by chemical reactions from 

emissions of oxides of nitrogen (NOx) and volatile organic compounds (VOCs) that occur in the 

atmosphere in the presence of sunlight. These pollutants are referred to as precursors of ozone. 

IEPA emissions data for NOx and VOC for 2005 are summarized in descending order by county 

for point, area, non-road and on-road (mobile) source categories in Figures 5 and 6. 

A point source is defined as a source whose emissions are generally discharged through stacks,

Area sources are defined as emissions that are spread over wide areas with no distinct discharge 

points (e.g. forest fires), or ones that are comprised of a large number of small point sources that 

are difficult to describe separately (e.g. residential fuel combustion). On-road mobile sources are 

classified as emissions from cars, trucks, buses, and motorcycles that are used for transportation 

of goods and passengers on streets and roads. Mobile non-road sources are characterized by 

emissions from other modes of powered transportation, such as airplanes, trains, ships, and offhighway motor vehicles.

Figures 5a and 5b, along with the accompanying tables, summarize IEPA’s 2005 estimated

emissions from point, area, non-road and on-road/mobile sources in the Chicago CSA for NOx

and VOCs. Figures 6a through 6b provide similar information for the St. Louis MSA, including

the adjacent counties of Randolph, Montgomery, Washington. Note that the Randolph County 

emissions for VOC, and NOx reflect 2005 reported emissions from the Baldwin power plant, as it 

is the only major contributing source in Baldwin Township of Randolph County. 

For the Chicago CSA Counties (Figures 5a-5b):

NOx emissions are highest in Cook County with the greatest emissions from on-road 

sources. Cook County contributes about 47% of total NOx emissions in the Chicago CSA 

counties. NOx emissions in Will, DuPage, and Lake Counties are also relatively high. 
13

Kendall, Grundy and DeKalb counties have relatively low emissions, which combined 

amount to approximately 5% of total NOx emissions. 

VOC emissions are highest in Cook County, with the greatest emissions coming from 

area sources. VOC emissions from Cook County are approximately 53% of the total 

VOC emissions in the area. DuPage, Lake and Will counties also have relatively high 

VOC emissions. VOC emissions are lowest in DeKalb, Kendall and Grundy counties; 

these counties combined contribute approximately 5% of total VOC emissions in the 

area. 

For the St. Louis MSA and Adjacent Counties (Figures 6a-6b):

NOx emissions are highest in Madison, Montgomery, St. Clair, and Randolph counties. 

Combined NOx emissions from Madison, Montgomery, St. Clair and Randolph counties 

contribute about 77% of total NOx emissions within the area. The greatest source 

contributors to the total NOx emissions for Madison, Montgomery, and Randolph 

counties are point sources, whereas the greatest source contributions in St. Clair County 

comes from on-road sources. Washington, Bond, Jersey, and Calhoun counties have 

relatively low emissions; combined they contribute to nearly 10% of total NOx emissions.

VOC emissions are highest in Madison and St. Clair counties, and account for nearly 

52% of total VOC emissions. In contrast, Clinton, Macoupin, Randolph, Montgomery, 

and Monroe VOC emissions contribute to 33% of total VOC emissions for the area. Area 

sources are the major contributor towards total VOC emissions for 2005. VOC emissions 

are lowest in Calhoun and Bond counties, with combined emissions contributing 

approximately 7% of total VOC emissions. 

Figures 7a through 7b depict both the locations and emission rates of major point sources in the 

current Chicago CSA for NOx and VOCs. . Emission totals are based on IEPA reported 

emissions for 2005. The orange solid shaded areas in the figures represent the areas being 

recommended as nonattainment for the new 8-hour ozone and counties bordered in blue 
14

represent counties included in the CSA/MSA where emission sources are evaluated as 

contributing to nonattainment. Figures 8a and 8b provide similar information for St. Louis MSA. 

Additional counties adjacent to the St. Louis MSA which are included in this analysis are 

Montgomery, Washington, and Randolph counties. 

For the Chicago CSA (Figures 7a-7b), the largest point sources for NOx are located in Will 

County. Cook and Lake counties also contain major point sources contributing NOx emissions. 

In comparison, Kankakee, Kendall, DeKalb, and Grundy counties have relatively few point 

sources emitting NOx with contributions only representing approximately 8% of total NOx

emissions. Both the largest size and greatest number of VOC point sources occur in Cook, Will, 

and Grundy counties. In comparison, DeKalb, Kankakee and Kendall counties have relatively 

few VOC point sources. 

For the St. Louis MSA (Figures 8a-8b), the largest point sources for NOx are located in Madison,

Montgomery and Randolph counties. Madison and St. Clair counties have the largest number of 

NOx emitting point sources, most emitting less than 100 tons per year. Adjacent counties have 

relatively few point sources emitting NOx. The largest emitting and greatest number of point 

sources emitting VOC’s are located in Madison and St. Clair counties. Adjacent counties have 

relatively few point sources emitting VOC’s. 

Population Density and Urbanization

Table 3 lists the population of each of the counties contained in the Chicago CSA and 

St. Louis MSA, as well as land areas, and population densities based on U.S. Census Bureau 

estimates for 2007. Figures 9 and 10 graphically depict population densities in the Chicago CSA 

and the St. Louis MSA, respectively. For the Chicago area, Cook, DuPage, Lake, and Will 

counties have the highest population and high population densities, while DeKalb and Grundy 

County have the lowest. Madison and St. Clair counties contain the majority of the Metro-East 

population, while Bond, Washington and Calhoun counties are considerably less populated.
15

TABLE 3

POPULATION and POPULATION DENSITY 

ESTIMATES BY COUNTY

Chicago CSA (Illinois Counties Only)

County Population 2007 Land Area 

(Square Mile)

Population Density 

(Persons per Sq. 

Mile)

Cook 5,285,107 945.68 5,589

DuPage 929,192 333.61 2,785

Lake 710,241 447.56 1,587

Kane 501,021 520.44 963

Will 673,586 836.94 805

McHenry 315,943 603.51 524

Kendall 96,818 320.58 302

Kankakee 110,705 676.75 164

DeKalb 103,729 634.16 164

Grundy 47,144 419.9 112

St. Louis MSA and Adjacent Counties

(Illinois Counties Only)

*Counties not included in St. Louis MO-IL MSA 

Source: U.S. Census Bureau estimate as of July 1, 2007, at http://factfinder.census.gov/

Source: U.S. Census Bureau’s State and County Quick Facts 

County Population 2007 Land Area

(Square Mile)

Population Density 

(Persons per Sq. 

Mile)

St. Clair 261,316 663.81 394

Madison 267,347 725.02 369

Clinton 36,450 472.23 77

Monroe 32,372 388.29 83

Jersey 22,455 369.16 61

Randolph* 32,760 578.42 57

Macoupin 48,235 863.57 56

Bond 18,103 380.2 48

Montgomery* 29,810 703.8 42

Washington* 14,769 562.61 26

Calhoun 5,167 263.62 20
16

Figure 11 illustrates the extent of the urbanized area within the Chicago CSA. According to the 

U.S. Census Bureau, MSA and CSA boundaries are dependent on a central urbanized area or 

contiguous area of relatively high population density. Outlying counties are included in MSAs if 

they exhibit strong social and economic ties to this core area, often measured by commuting and 

economic patterns. Therefore, it is logical to conclude that the urbanized area in Boone County 

is not directly influencing emissions in the Chicago CSA. A pattern of fragmented urban 

development and commuting is also apparent in DeKalb, Kankakee and parts of Grundy 

counties. County urban extents are not contiguous with the Chicago CSA.

In the St. Louis MSA and adjacent county area, urbanization is not as pronounced as seen in the 

Chicago CSA (See Figure 12). Madison and St. Clair counties are the most urbanized of the 

counties in the Metro-East portion of the St. Louis MSA. Adjacent counties such as Washington, 

Montgomery and Randolph are not included in the St. Louis MSA and exhibit a fragmented 

population with the Metro-East urban core. Based on the non-contiguous pattern of 

urbanization, it is logical to conclude that Washington, Montgomery, and Randolph counties are 

not influencing emissions related to social, economic and population growth in the Metro-East.

Figures 13 and 14 depict current land cover for both the Chicago CSA and St. Louis MSA areas 

based on data compiled by the Illinois Department of Agriculture. According to the “Land 

Cover of Illinois 1999-2000 On-Line Statistical Summary”, the Chicago CSA has the most 

urbanized counties in the state. A high degree of urbanization is apparent in both Cook (79.9%) 

and DuPage (77.5%) counties. Lake County is also highly urban, with 48.3% of the county 

classified as urban or built-up land. In each of the Chicago area counties of Kane, Will and 

McHenry the land cover is dominated by agriculture ranging from 63 to 67% and the amount of 

urban and built-up land is less than 25% of the total land cover. The primarily rural counties of 

Kendall, DeKalb, Grundy and Kankakee have less than 6% urban land; however each county’s 

land cover is greater than 80% agriculture.
17

Unlike the Chicago CSA, all nonattainment counties in the Metro East/St. Louis MSA area have 

high percentage of agriculture land (greater than 49 %). Madison and St. Clair counties have the 

greatest urban land cover in the Metro-East area. (See Figure 14). The counties of Calhoun, 

Jersey, Macoupin, Monroe, Bond and Clinton have less than 4% urban built-up land. The 

dominance of agricultural land use, coupled with the low population densities in these counties, 

confirm that they are primarily rural in nature.

Growth Rates and Patterns

Short term population growth is an important indicator of potential emission increases in an area. 

Figures 15 and 16 outline percent change in population between 2000 and 2007 by county for 

both the Chicago CSA and St. Louis MSA. This data was provided by the U.S. Census Bureau 

and is based on estimates dated March 22, 2007. According to the data, the Chicago CSA county 

of Kendall has experienced the greatest percent increase in population at 75.4%; however its

total population is relatively small compared to other counties in the CSA. Cook County has 

experienced an estimated 2.7% decrease in population; however its total population for 2007

represents approximately 60% of the population base in the Chicago CSA area. According to the 

U.S Census Bureau, the Metro-East county of Monroe has experienced the greatest percent 

increase in population at 16.6%. Jersey County has experienced a moderate population change at 

3.7%, while Randolph County experienced a loss in total population (-3.4%).

Population and economic trends are developed for long range planning activities by both State 

and local governmental agencies. Data compiled by the Illinois Department of Commerce and 

Economic Opportunity (DCEO) were referenced for this analysis and are shown in Figure 17. In 

the Chicago CSA, the highest total population growth between 2000 and 2030 is projected to 

occur in Cook and Will counties. The lowest growth in terms of net population change is 

projected for DeKalb, Grundy, Kendall, and Kankakee counties. In the Metro-East area, long 

term population growth is projected to be highest in Madison, Monroe and Macoupin counties, 

and lowest in Randolph, Jersey, Bond, Clinton and Calhoun counties. According to this study, 

St. Clair County is expected have a decrease in population in future years.
18

Occupational employment growth projections between 2004 and 2014 were provided by DCEO 

and compiled from projections developed by the Illinois Department of Employment Security, 

and are shown in Figure 18. In the Chicago area, the highest rate of occupational employment 

growth is expected to occur in Cook and DuPage counties, moderate increases in employment 

are expected to occur for Lake, Kane and Will counties, while the lowest rates of employment 

growth are expected in Kankakee, DeKalb, Kendall, and Grundy counties. In the Metro-East 

area, moderate employment growth is forecast for Madison County while relatively low 

employment growth is expected to occur in St. Clair, Monroe, Clinton, Jersey, Bond, 

Washington and Macoupin counties. Based on this study, Randolph County is expected to 

experience job losses in the future.

Traffic and Commuting Patterns

The Illinois Department of Transportation’s (IDOT) Office of Planning and Programming 

publishes an annual report entitled Illinois Travel Statistics. This report provides much useful 

information on Illinois traffic, including Vehicle Miles Traveled (VMT) data by county, derived 

from IDOT’s Traffic Count Program. Table 4 and Figures 19 and 20 summarize IDOT’s 

estimates of Average Daily Vehicle Miles Traveled (ADVMT) in 2007, as calculated by IDOT’s 

Highway Information System.

Table 4

Average Daily Vehicle Miles Traveled 

for Selected Counties

from Illinois Travel Statistics 2007

Chicago

Consolidated Statistical 

Area (CSA) County

Average Daily 

Vehicle Miles 

Traveled (ADVMT) 

Cook 89,983,183

DuPage 23,653,693

Lake 15,747,091

Will 15,583,052

Kane 9,995,846

McHenry 6,071,071
19

Kankakee 2,638,934

DeKalb 2,389,212

Kendall

 Oswego NAA Township

2,150,002

737,471

Grundy

 Aux Sable NAA Township

 Goose Lake NAA Township

1,904,904

394,274

47,695

St. Louis

Metropolitan Statistical 

Area (MSA) County

Average Daily 

Vehicle Miles 

Traveled (ADVMT)

Madison 7,943,331

St. Clair 7,507,369

Montgomery* 1,402,503

Macoupin 1,170,604

Clinton 1,098,142

Washington* 1,088,059

Monroe 1,010,593

Bond 803,052

Randolph* 729,219

Jersey 539,760

Calhoun 111,684

* Montgomery, Randolph and Washington Counties are not part 

of the MSA

County ADVMT is calculated by dividing County Annual VMT by 365, the number of days in a 

year (366 in a leap year). The ADVMT on a segment of road is calculated by multiplying the 

Average Daily Traffic on the segment by the length of the segment in miles. 

In the Chicago area, Cook, DuPage, Lake, and Will counties have the highest ADVMT. In fact, 

the ADVMT in these four counties account for approximately 85% of the total for the Illinois 

portion of the CSA. Collectively, Kankakee, DeKalb, Kendall, and Grundy counties account for 

about 5% of the total ADVMT in the CSA. In the 11 counties listed above, Madison, St. Clair, 

and Montgomery Counties have the highest ADVMT, and account for 72% of the VMT in the 

11-county area. Randolph, Jersey, and Calhoun Counties have the lowest VMT, with about 6% 

of the 11 county total VMT. In addition, VMT has decreased in most of the State in the last few 
20

years (see Figure 21 and 22), and was nearly the same in the existing 8-hour ozone 

nonattainment areas (NAAs) in 2007 as it was in 2002 and 2003. 

The U. S. Census Bureau has compiled statistics from the 2000 census that quantify commuting 

patterns in the Chicago and St. Louis metropolitan areas. Figures 23 and 24 illustrate where 

people reside and the counties where they journey to work. Each county is color-coded on the 

histograms. For example, Cook County is shown in Figure 23 as a blue bar in each county’s 

histogram. The data show that 2.07 million people reside in Cook County and commute within 

Cook County to reach their place of employment, but only 826 people reside in Cook County 

and commute to DeKalb County for employment. In some counties, a significant percentage of 

commuters travel to places of employment in other counties. For example, 146,135 residents of 

DuPage County commute to Cook County for employment. Similarly, a large percentage of 

commuters residing in Kendall County travel to Will and Kane counties for employment, 

although the number of commuters residing in Kendall County is small relative to the number of 

commuters in the Chicago CSA. From Figure 23, it is evident that more commuters in the 

Chicago CSA travel to places of employment in the county where they reside than travel to other 

counties. Commuting patterns in the St. Louis MSA (see Figure 24) are similar in that more 

commuters stay in their residence county for work than commute to surrounding counties.

Topography

Illinois is typified by flat to gently rolling terrain, with the exception of the Driftless Area in the 

northwest corner of the state and the Ozark Plateau in southern portion of the state (see Figure 

25). Illinois occupies a land mass of approximately 55,584 square miles. The average elevation 

of the state is approximately 600 feet (183 m) above sea level. Charles Mound, located in Jo 

Davies County, is the highest point in the state with an elevation of 1,235 feet (376 m) above sea 

level. The lowest point in the state is 279 feet (85 m) above sea level along the Mississippi River 

in Alexander County. Total topographic relief across the state is less than 1000 feet, 

demonstrating the general flatness of the terrain. Topography is generally not a factor in 

determining pollutant transport in Illinois, and is not considered a significant issue in defining 
21

the boundaries of the 8-hour ozone nonattainment areas.

Jurisdictional Boundaries

Jurisdictional boundaries considered in this analysis are consistent with recommended 

geographic boundaries or “presumptive boundary” definitions outlined in the ozone guidance 

documentation. Boundaries in this study reflect July 2003, OMB CSA and CBSA boundary 

definitions. Counties within the St. Louis, St. Charles-Farmington, MO-IL CSA within the state 

of Illinois are consistent with those counties included with the St. Louis MO-IL MSA. 

Additional counties are only included within Missouri under this St. Louis CSA definition. 

Proposed boundaries for nonattainment are consistent with existing 8-hour ozone nonattainment 

boundaries (1997 ozone NAAQS) as well as the previous 1-hour ozone NAA boundaries. 

Proposed ozone NAA areas in the Chicago CSA are the same as the current PM2.5 NAA 

boundaries and the proposed ozone St. Louis NAA includes three of the four counties in the 

PM2.5 NAA. Based on these geographic similarities it is expected that the coordination of 

planning activities required to address nonattainment designations can be carried out in a 

cohesive manner.

Meteorology

Illinois has a temperate climate, with cold winters and hot humid summers. The seasons are 

sharply differentiated between the northern and southern portions of the state, due to its 

elongated north-south orientation. Average winter temperatures are 22°F (–6°C) in the north and 

37°F (3°C) in the south. Average summer temperatures are 70°F (21°C) in the north and 77°F 

(25°C) in the south. Illinois averages 36 inches (91 cm) of precipitation a year. Annual snowfall 

of 37 inches (94 cm) is normal for northern Illinois, decreasing to 14 inches (36 cm) or less in the 

southern portions of the state. The predominant wind direction across the state is from the 

south/southwest, with an average wind speed of approximately 11 miles per hour.
22

Monitors in the Chicago area that exceed the new ozone design value (2006-2008) show strong

evidence of regional influences based on previous data analyses and modeling. Figure 26, 

contains a pollution rose based on the three year period from 2006–2008 which supports this 

contention. This pollution rose incorporates Alsip wind data for days with monitored 

exceedances. Exceedances may occur at one or more monitoring site(s) on a given day. The 

length of each blue or red line represents the percentage of time that the wind blew from a 

particular direction on days when ozone concentrations were > 75 ppb. Based on this 

information, the predominant wind direction ranged from south to southwest on high 

concentration days instead of from the urban core to the north. 

In the Metro-East Area, regional influences have been shown through previous modeling studies

to be a significant factor contributing to monitored violations of the ozone standard. The 

pollution rose for the Metro-East area representing Edwardsville winds and Illinois Metro-East 

monitoring sites shows predominant wind directions ranging from south to south-southeast (see 

Figure 27) on days with elevated levels of ozone. These wind directions indicate that a 

substantial portion of the regional background is coming from sources in the Ohio River Valley

and the southeastern U.S.. Meteorology for all Metro-East sites on high days > 75ppb identifies 

the same general wind conditions (see Figure 27).

Level of Control of Emission Sources

Emission control measures which have been promulgated at the federal and state levels, in 

combination with court-approved consent decrees, have impacted emission levels from a wide 

spectrum of emission sectors in the Metro-East St. Louis area. These have led to significant air 

quality improvements. Further emission reductions through planned or pending rulemakings are 

expected to enhance these air quality gains. Principal among existing and pending emission 

reduction measures include the following:
23

Electricity-Generating Power Plants

Clean Air Act Title IV (Phases I and II)

NOx SIP Call

Illinois Multi-Pollutant Strategy (MPS/CPS)

Clean Air Interstate Rule (CAIR)

Dynegy Midwest Generation Consent Decree

Other Stationary Point Sources

NSPS and NESHAPS/MACT

ConocoPhillips Consent Decree

NOx RACT Rulemaking (not yet adopted by IPCB)

Area Sources

Aerosol Coatings, AIM Coatings, Household and Institutional Consumer Solvents

Portable Fuel Containers

On-Highway Mobile Sources

Tier 2 Motor Vehicle Standards / Gasoline Sulfur Requirements

Heavy-Duty Engine Standards / Highway Diesel Sulfur Requirements

Reformulated Gasoline

Vehicle Inspection & Maintenance Program

Evaporative Large Spark Ignition and Recreational Vehicle Standards

Off-Highway Mobile Sources

Tier 4 Nonroad Diesel Engines / Diesel Sulfur Requirements

Marine Compression-Ignition Standards

Locomotive Engine Standards

Permitting activities result in issuance of new construction permits which add to ambient ozone 

precursor emission levels. Typically, state-of-the-art emission controls are required on these new 

emission sources before they can operate, and thus greatly limit additional ozone precursor 

loadings due to new construction. The Prairie State Generating Company, LLC mine-mouth 

coal-fired power plant that is currently under construction in Washington County, Illinois, 

underwent a rigorous regulatory review prior to receiving a Prevention of Significant 

Deterioration permit. Boiler operations and virtually all other emission sources at this facility are 

subject to stringent emission control levels. Similarly stringent emission limitations have been 
24

placed on other new construction and operating permits for industrial facilities in counties 

adjoining or within the Metro-East area. 

RECOMMENDATIONS

The CAA does not specify the geographic boundaries, size, or the extent to which source 

contributions would require that an area be designated as nonattainment for the 8-hour ozone 

standard, nor has U.S. EPA promulgated rules prescribing such. IEPA’s recommendations are 

consistent with a guidance memorandum provided by U.S. EPA (December 4, 2008), and are 

based on an evaluation of present and projected air quality, the distribution of precursor 

emissions, and other factors. The IEPA recognizes that each of the factors considered in this 

evaluation are not necessarily conclusive when evaluated individually. Rather, IEPA’s 

recommendations are based on consideration of all of the data and projections taken together.

Documentation of data sources utilized in this analysis is shown in Table 6.

IEPA’s recommendations for attainment/nonattainment designations in Illinois for the 8-hour 

ozone ambient air quality standards are contained in Table 7. Current air quality data collected 

by the IEPA indicate that the only areas of Illinois where the 8-hour ozone air quality standard is 

not being met are in portions of the Chicago and Metro-East metropolitan areas. Nonattainment 

designations for at least portions of these metropolitan areas are, therefore, warranted. The 

IEPA’s recommendation for inclusion of counties within the boundaries of the nonattainment 

areas are discussed in the following section and geographically depicted in Figure 28.

Chicago Metropolitan Area

Cook County: Cook County is the only county in northeastern Illinois where current air quality 

data (2006-2008) does not meet the 8-hour ozone standard (Alsip monitor). Cook County is 

currently designated nonattainment for the existing 8-hour ozone standard as well as the previous 

1-hour ozone standard. In terms of precursor emissions, Cook County has the highest levels of 

both VOC and NOx emissions of any of the ten counties in the CSA. Demographically, Cook 

County has the highest population, the highest population density, and the largest acreage of 
25

urban land cover of all the counties in the CSA. The IEPA, therefore, recommends Cook County

be included in the Chicago nonattainment area for the 8-hour ozone standard.

Lake County: Lake County is currently designated nonattainment for the existing 8-hour ozone 

standard as well as the previous 1-hour ozone standard. Lake County has high levels of 

precursor emissions, relatively high total population and population density, a high percentage of 

urban land cover, and high levels of vehicular traffic. The IEPA, therefore, recommends that 

Lake County be included in the Chicago nonattainment area for the 8-hour ozone standard.

DuPage and Will Counties: Both DuPage and Will Counties are currently designated 

nonattainment for the current 8-hour standard as well as the previous 1-hour ozone standard. 

DuPage and Will Counties have some of the highest levels of precursor emissions in the Chicago 

CSA. DuPage County is second only to Cook County in total population, population density, 

vehicular traffic, and total urban land cover. Similarly, Will County has a relatively high 

population, population density, population growth, traffic level, and urban land coverage. The 

IEPA, therefore, recommends that DuPage and Will Counties be included in the Chicago 

nonattainment area for the 8-hour ozone standard.

McHenry and Kane Counties: McHenry and Kane Counties are on the western fringe of the 

metropolitan area with the eastern portions of these counties having an urban/suburban character, 

while the western portions are basically rural. These counties have moderate levels of precursor 

emissions relative to Cook, Lake, DuPage, and Will Counties, and the total population, 

population density, and total urban land cover in these counties are also relatively moderate. 

McHenry and Kane Counties are experiencing moderate population and employment growth. 

Both McHenry and Kane Counties are currently designated nonattainment for the existing 8-hour 

ozone standard as well as the previous 1-hour standard. The IEPA, therefore, recommends that 

McHenry and Kane Counties be included in the Chicago nonattainment area for the 8-hour ozone 

standard.
26

DeKalb and Kankakee Counties: DeKalb and Kankakee Counties were added to the list of CSA 

counties by the U.S. Census Bureau in 1998 and were not included in the Chicago nonattainment 

area for the previous 1-hour ozone standard. They were also classified as attainment for the 

1997 8-hour ozone standard. These counties are primarily rural, as shown by their low 2007 

population totals and population densities, and the small amount of urban land cover in each 

county is not contiguous with the Chicago urbanized area. Current precursor emission levels in 

these counties are also low, compared to the other counties in the CSA. For these reasons, the 

IEPA recommends that DeKalb and Kankakee Counties not be included in the nonattainment 

area and that they be designated as attainment for the 8-hour NAAQS for ozone.

Grundy and Kendall Counties: Oswego Township in Kendall County and Goose Lake and Aux 

Sable Townships in Grundy County are included in the existing 8-hour ozone NAA. Due to their 

primarily rural character, most of Grundy and Kendall Counties were not included in the 

previous Chicago 1-hour nonattainment area, the boundaries of which were established 

subsequent to the 1990 Amendments to the CAA. Certain townships in Grundy and Kendall 

Counties were included in the previous 1-hour nonattainment area due to the significance of 

certain stationary, or point, sources as indicated by the IEPA’s 1990 emissions inventory. 

Precursor emission levels in the remaining portions of these counties are low, as is the total 

population, population density, traffic volumes, and total urban land cover. For these reasons, 

the IEPA recommends that Oswego Township in Kendall County and Goose Lake and Aux 

Sable Townships in Grundy County be included in the Chicago nonattainment area for the 8-

hour NAAQS for ozone, but that the remainder of these two counties should retain their current 

classification of attainment.

St. Louis Metropolitan Area 

Madison County: Madison County is the only county in the St. Louis MSA where current air 

quality data (2006-2008) does not meet the 8-hour ozone standard (3 monitors). Madison County 

is currently designated nonattainment for the existing 8-hour standard and a maintenance area for 

the previous 1-hour ozone standard. In terms of precursor emissions, Madison County has the 
27

highest levels of both VOC and NOx emissions of any of the counties in the Metro-East. 

Demographically, Madison County has the highest population, the second highest population 

density, the largest acreage of urban land cover and highest volume of traffic of all the counties 

in the Metro-East. Madison County should be included in the St. Louis Metro-East 

nonattainment area for the 8-hour standard.

St. Clair County: Air quality data from the most recent 3-year period (2006-2008) indicate that 

St. Clair County currently meets the new 8-hour ozone standard. However, it is currently 

designated nonattainment for the 1997 8-hour standard and a maintenance area for the previous 

1-hour ozone standard. St. Clair County has relatively high levels of both VOC and NOx 

emissions, relatively high total population and population density, and a large percentage of 

urban land cover. St. Clair County is expected to experience negative population growth and 

moderate employment growth in future years. The IEPA, therefore, recommends that St. Clair 

County be included in the St. Louis Metro-East nonattainment area for the 8-hour standard.

Monroe County: Monroe County is on the southern fringe of the Metro-East area with the 

northern portions of the county having an urban/suburban character, while the southern and 

eastern portions of the county are basically rural. It is currently designated as nonattainment for 

the 1997 8-hour standard as well as a maintenance area for the previous 1-hour ozone standard. 

This county has relatively low levels of precursor emissions relative to Madison and St. Clair 

Counties, and the total population, population density, and total urban land cover is also 

relatively low. Because of its existing status as an ozone NAA for the 1997 NAAQS and its 

previous designation as a 1-hour ozone maintenance area, the IEPA recommends that Monroe 

County be included in the St. Louis Metro-East nonattainment area for the 8-hour ozone 

standard. 

Jersey County: Jersey County is a rural county located to the north of St. Louis, and is currently 

attaining the 8-hour ozone standard. This county has low levels of precursor emissions, low 

population and population density, low urban land cover, low population and employment 

growth rates as well as low volumes of traffic. The character of Jersey County is distinctly 
28

different from the St. Louis metropolitan area and air quality data from the most recent 3-year 

period (2006-2008) indicates that Jersey County is meeting the 8-hour ozone standard. Jersey 

County is downwind from the violating monitor and therefore, does not contribute to violations 

in the proposed NAA. For this reason, the IEPA recommends that Jersey County be designated 

as attainment for the 8-hour NAAQS for ozone.

Clinton County: As mentioned previously, the current (1998) MSA boundaries established by 

the Office of Management and Budget, for St. Louis include Clinton County, Illinois. Clinton 

County was not contained within the previous 1-hour ozone nonattainment area. This county is 

primarily rural, with low 2007 population totals and population densities, and small amounts of 

urban land cover, compared to other counties in the MSA. Current precursor emission levels in 

Clinton County are low, as are expected rates of population and employment growth. For these 

reasons, the IEPA recommends that Clinton County be designated as attainment for the 8-hour 

NAAQS for ozone.

Randolph County: Randolph County is not part of the St. Louis MSA as defined by the Office 

of Management and Budget. It is not included as part of the existing 8-hour ozone NAA and was 

not contained within the previous 1-hour ozone nonattainment area. This rural county has low 

population and population density, low urban land cover, and low population and employment 

growth rates. Randolph County has high levels of precursor emissions of NOx, virtually all of 

which are emitted from an existing, stationary emission source, the Baldwin Power Station. The 

Baldwin Power Station is subject to Illinois multi-pollutant strategy controls as well as a federal 

consent order which will significantly reduce NOx emissions in future years. For these reasons, 

the IEPA recommends that Randolph County be designated as attainment for the 8-hour NAAQS 

for ozone.

Macoupin, Bond and Calhoun Counties: Bond, Calhoun and Macoupin counties were added to 

the St. Louis MO-IL MSA as defined by the U.S. Census Bureau, in 2003. All three counties are 

not included in the existing 8-hour ozone nonattainment area. These counties are primarily rural, 

with low 2007 population totals and population densities, and have small amounts of urban land 
29

cover, compared to other counties in the St. Louis MSA. Current precursor emission levels in 

Macoupin, Bond and Calhoun counties are low, as are expected rates of population, employment 

growth and VMT. For these reasons, the IEPA recommends that Macoupin, Bond and Calhoun 

counties be designated as attainment for the NAAQS for 8-hour ozone.

Montgomery County: Montgomery County is not included in the existing 8-hour ozone

nonattainment area, nor is it part of the St. Louis MSA. The county is not contiguous with the 

Metro-East urbanized area and does not influence population and economic growth in the MSA. 

Based on 2005 emissions data high precursor emission totals are the results of a large electric 

utility source which is more than 40 miles away from the violating monitor and is downwind 

from the Metro-East area. Further, this source is subject to Illinois multi-pollutant requirements 

which will greatly reduce NOx emissions in future years. For these reasons, the IEPA 

recommends that Montgomery County not be included in the nonattainment area and that it be 

designated as attainment for the NAAQS for 8-hour ozone.

Washington County: Washington County is not included in the existing 8-hour ozone

nonattainment area, nor is it part of the St. Louis MSA. Washington County is considered 

adjacent to St. Clair County; however the county is not contiguous with the Metro-East 

urbanized area and exhibits low population, VMT and economic influence. Current precursor 

emission levels in these counties are very low, compared to the other counties evaluated for this 

analysis, although a new electric generating unit is being constructed that will increase emissions 

in the near future. This source has been permitted under the Prevention of Significant 

Deterioration program which requires the installation of Best Available Control Technology.

For these reasons, the IEPA recommends that Washington County not be included in the 

nonattainment area and that it be designated as attainment for the NAAQS for 8-hour ozone.
30

Remainder of Illinois

Areas of the state that are not part of these two metropolitan areas are in attainment with the 

8-hour ozone NAAQS, and it is recommended that all remaining counties be designated as 

attainment.
31

Table 5

Recommended Attainment/Nonattainment Designations in Illinois

For the 8-hour Ozone National Ambient Air Quality Standard

County Designation Name of Area

Cook Nonattainment Chicago

DuPage Nonattainment Chicago

Kane Nonattainment Chicago

Lake Nonattainment Chicago

Will Nonattainment Chicago

McHenry Nonattainment Chicago

Kendall:

 Oswego Township

 All Other Townships

Nonattainment

Attainment

Chicago

Grundy:

 Aux Sable Township

 Goose Lake Township

 All Other Townships

Nonattainment

Nonattainment

Attainment

Chicago

Chicago

Madison

 Aux Sable Township

 Goose Lake Township

 All Other Townships

Nonattainment Metro-East

Monroe Nonattainment Metro-East

St. Clair Nonattainment Metro-East

All Other Counties Attainment
32

Factor Data Analysis Data Source Date of Study

1. Air Quality Data- Monitoring

Ozone 2006-2008 Design Values 

at individual monitors 

(statewide)

IEPA BOA Database, 

Air Monitoring Section

2006-2008

2. Emissions Data

Emission inventory information 

for pollutants: NOx, and VOC 

within the Chicago CSA and St. 

Louis MSA/CSA and adjacent 

counties. Emission totals 

(tons/year) are summarized by 

county for point, area, onroad/mobile, and off-road sectors

IEPA 2005 Reported 

Inventory

2005

Source locations in nonattainment areas and adjacent 

counties

IEPA BOA database 2005

3. Population Density and 

Degree of Urbanization

Annual Estimates of the 

Population in Illinois. Total 

population and population 

density estimates*

Urbanized area boundaries 

Table1:Annual 

Estimates of the 

Population for Counties 

of Illinois: July 1, 2000 

to July, 2007

(CO-EST2007-03-22)

Population Division, 

U.S. Census Bureau;

ESRI Maps and Data

Release date:

2007

4. Expected Growth Rates and 

Patterns

Total population change based 

on Long-Term population 

projection **

Total occupational employment 

change based on Long Term 

study**

Illinois Department of 

Commerce and 

Economic Opportunity: 

Illinois Population 

Trends 2000-2030

Illinois Department of 

Employment Security

2000-2030 

Population 

Projection 

Table - 2005 

edition

2004-2014 

Occupational 

Employment 

Projections by 

County – 2005 

edition

5. Traffic and Commuting 

Patterns

Average Daily Traffic tables for 

2007

County to County Commuting 

Workflow files table

Illinois Department of 

Transportation, Travel 

Statistics 2007;

U.S. Census Bureau 

2007

2000

Table 6

8-hour Ozone NAA Boundary Recommendation 

Nine Factor Documentation 

March 9, 2009
33

* http://www.census.gov

** http://www.commerce.state.il.us/dceo/Bureaus/Facts_Figures

6. Topography

relatively flat

Google Earth;

U.S. Geological Survey

2007 (data is 

about one to 

three years old 

and updated on 

a regular basis–

no set year is 

given)

7. Jurisdictional Boundaries MSA/CBSA/CSA boundary 

information; 

Office of Management 

and Budget;

( in conjunction with 

U.S. Census Bureau)

2003;

April 2005

8. Meteorology Weather patterns –

Pollution/Wind Rose, Regionally 

Influenced High days

Chris Price (Air 

Monitoring Section);

Illinois State Water 

Survey

2006-2008

9. Level of Control of Emission 

Sources

Existing and expected controls IEPA – BOA Programs 2008
Figure 1
Figure 2
Figure 3

2006-2008 Lake Michigan

8-Hour Ozone Design Values
Figure 4

2006-2008 St. Louis, MO

8-Hour Ozone Design Values
Figure 5a

2005 NOx Emissions by County for the Chicago CSA

(Tons/Day)

 NOx

COUNTY POINT AREA NONROAD ONROAD

Total 

Tons/Day

Cook 68.42 19.98 161.61 186.16 436.17

Will 110.06 1.16 33.08 31.25 175.55

DuPage 5.72 5.03 33.33 47.02 91.10

Lake 27.47 3.61 18.64 30.47 80.19

Kane 2.67 1.89 19.63 20.47 44.66

Kankakee 17.2 0.28 7.51 6.75 31.74

McHenry 2.32 1.44 12.08 11.91 27.75

Grundy 3.51 0.11 5.72 6.65 15.99

Kendall 7.11 0.30 4.55 3.59 15.55

DeKalb 0.65 0.32 5.6 6.07 12.64
Figure 5b

2005 VOC Emissions by County for the Chicago CSA

(Tons/ Day)

VOC

COUNTY POINT AREA NONROAD ONROAD

Total 

Tons/Day

Cook 40.80 166.99 77.44 77.91 363.14

DuPage 5.58 31.05 24.52 19.68 80.83

Lake 3.63 23.49 24.20 13.43 64.75

Will 10.04 22.76 13.49 12.56 58.85

Kane 4.91 16.64 12.47 8.51 42.53

McHenry 2.29 11.45 7.88 5.34 26.96

Kankakee 3.90 7.69 2.36 3.58 17.53

DeKalb 1.02 7.44 1.78 3.29 13.53

Grundy 2.48 3.87 2.51 2.19 11.05

Kendall 1.41 4.47 2.82 2.31 11.01
Figure 6a

 NOx

COUNTY POINT AREA NONROAD ONROAD

Total 

Tons/Day

Madison 39.10 0.59 17.31 20.88 77.88

Montgomery* 38.41 0.12 6.19 5.14 49.86

St. Clair 2.17 0.56 7.75 18.54 29.02

Randolph* 16.78 0.19 9.57 1.56 28.10

Monroe 0.75 0.08 8.16 2.34 11.33

Clinton 3.57 0.11 4.76 2.75 11.19

Macoupin 0.06 0.14 4.74 3.42 8.36

Washington* 0.04 0.08 4.21 3.98 8.31

Bond 0.06 0.05 3.00 3.08 6.19

Jersey 0.00 0.05 4.69 1.16 5.90

Calhoun 0.00 0.01 4.10 0.22 4.33

* County is not in MSA
Figure 6b

VOC

COUNTY POINT AREA NONROAD ONROAD

Total 

Tons/Day

Madison 8.78 13.02 6.67 8.14 36.61

St. Clair 3.46 11.47 4.73 7.73 27.39

Clinton 0.31 3.29 4.33 1.43 9.36

Macoupin 0.11 5.38 1.63 1.64 8.76

Montgomery* 0.40 4.59 1.78 1.86 8.63

Randolph* 1.12 3.03 3.16 1.03 8.34

Washington* 0.25 3.01 1.01 1.31 5.58

Monroe 0.13 2.30 1.77 1.16 5.36

Jersey 0.08 2.23 1.56 0.78 4.65

Calhoun 0.00 0.88 3.47 0.15 4.50

Bond 0.11 2.23 0.96 1.06 4.36

* County is not in MSA
Figure 7a Figure 7b
Figure 8a Figure 8b
Figure 9
Figure 10
Figure 11

 
Figure 12
Figure 13
Figure 14
Figure 15

-10.0

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

Cook

DuPage

Kankakee

Lake

DeKalb

McHenry

Kane

Grundy

Will

Kendall

-1.7

2.5 6.6

9.6

16.1

20.6 22.9 25.1

32.6

75.4

Population Change (%)

County

2000 

Population 

2007 

Population 

Kendall 55,207 96,818

Will 508,067 673,586

Grundy 37,674 47,144

Kane 407,584 501,021

McHenry 261,887 315,943

DeKalb 89,331 103,729

Lake 648,241 710,241

Kankakee 103,881 110,705

DuPage 906,760 929,192

Cook 5,377,927 5,285,107
Figure 16
Figure 17
Figure 18
Figure 19

0

10

20

30

40

50

60

70

80

90

100

Cook DuPage Lake Will Kane McHenry Kankakee DeKalb Kendall Grundy

90.0

23.7

15.7 15.6

10.0

6.1

2.6 2.4 2.2 1.9

Millions of ADVMT

County

2007 Average Daily Vehicle Miles Traveled (ADVMT)

in the Chicago Area (millions)
Figure 20

0

1

2

3

4

5

6

7

8

9

10

7.9

7.5

1.4 1.2 1.1 1.1 1.0 0.8 0.7 0.5

0.1

Millions of ADVMT

County

* denotes counties not part of St. Louis MSA

2007 Average Daily Vehicle Miles Traveled (ADVMT) 

in the St Louis Area (millions)
Figure 21

Average Daily VMT in the Chicago NAA, 1990 - 2007

IDOT Travel Statistics

Figures Show ADVMT to the nearest million

Chicago NAA + 3 Nonattainment Townships 

in Grundy & Kendall Counties
Figure 22

Average Daily VMT in the Metro-East NAA, 1990 - 2007

IDOT Travel Statistics

Figures Show ADVMT to the nearest million

Metro-East NAA (Madison, Monroe & St. Clair Counties) 
Figure 23

0

50,000

100,000

150,000

200,000

250,000

300,000

*Cook DeKalb DuPage Grundy Kane Kankakee Kendall Lake McHenry Will

Cook 2,077,798 2,221 152,433 1,123 34,361 4,559 2,459 83,502 31,337 76,574

DeKalb 826 28,811 560 7 1,311 0 725 60 202 149

DuPage 146,135 2,857 277,934 765 34,318 471 7,051 6,967 4,650 43,498

Grundy 533 19 260 8,884 51 202 299 24 47 2,702

Kane 18,345 6,468 16,539 296 107,807 30 6,630 1,383 8,877 3,432

Kankakee 977 0 95 98 36 36,936 8 8 0 1,352

Kendall 837 1,263 949 180 2,866 12 8,798 64 73 1,097

Lake 64,253 249 5,377 68 3,012 63 108 212,450 16,731 1,128

McHenry 5,182 448 884 23 5,056 4 20 5,866 68,108 158

Will 24,432 349 9,197 5,869 1,840 3,564 1,737 389 343 107,456

*2,077,798

Number of Workers Commuting

Where People Reside and Counties Where they Journey to Work

Chicago CSA Counties

Resident County
Figure 24

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

Bond Calhoun Clinton Jersey Macoupin Madison Monroe Montgomer

y

Randolph St. Clair Washington

Monroe 18 0 20 0 0 421 5,367 0 623 1,730 8

Jersey 7 38 0 4,473 204 3,480 0 7 6 111 0

Calhoun 0 1,099 0 208 12 362 0 5 2 13 0

Clinton 256 0 8,567 0 22 1,598 20 16 41 2,586 309

Macoupin 14 2 0 238 11,335 3,897 7 1,516 14 315 0

Bond 4,168 0 248 0 42 1,471 4 292 13 201 10

Washington 5 0 340 0 23 94 0 0 228 786 4,408

Madison 289 39 460 506 650 75,494 70 239 322 9,317 21

St. Clair 29 0 479 30 61 7,044 916 57 871 70,379 179

Montgomery 153 8 12 7 542 288 0 8,843 23 75 0

Randolph 6 0 30 0 0 181 485 4 9,545 1,162 144 Number of Workers Commuting

Resident County

Where People Reside and Counties Where they Journey to Work

ST. Louis MSA and Adjacent Counties
Figure 25

Topography
 Figure 26

Chicago Area Pollution Rose 

2006 – 2008

All sites

Days > 75ppb

Meteorology based on Alsip 2006-2008
Figure 27

 Metro-East Pollution Rose (2006 – 2008)

All sites

Days > 75ppb

Meteorology based on Edwardsville 2006-2008
Figure 28