______1 ••

ATTACHMENT 112

State of Illinois

Rod R. Blagojevich, Governor

Illinois Environmental Protection Agency

Douglas P. Scott, Director

Illinois Base Year

Ozone Inventory

for 2002

June 2006
AQPSTR06-03

Illinois Base Year

Ozone Inventory

for 2002

Illinois Environmental Protection Agency

1021 North Grand Avenue East

P.O. Box 19276

Springfield, Illinois 62794-9276

Draft: June 2006
Table of Contents 

Section Page

1.0 Introduction.................................................................................................1 

2.0 Emission Inventory Summaries ..................................................................3 

 2.1 Background......................................................................................3 

 2.2 Methodology ....................................................................................4 

 2.2.1 Point Sources........................................................................7 

 2.2.2 Area Sources ........................................................................7 

 2.2.3 Mobile Sources .....................................................................7 

 2.3 Results.............................................................................................8 

 2.3.1 Statewide Emissions ...........................................................17 

 2.3.2 Chicago NAA Emissions .....................................................17 

 2.3.3 Metro-East NAA Emissions.................................................18 

 2.3.4 Attainment Area Emissions .................................................18 

3.0 Point Sources ...........................................................................................29 

 3.1 Point Source Process Emissions ...................................................29 

 3.1.1 Source Identification and Data Collection ...........................30 

 3.1.2 Non-reactive VOM Emission Adjustments ..........................30 

 3.1.3 Emission Estimation Methodologies....................................30 

 3.2 Point Source Fugitive Emissions ...................................................30 

 3.2.1 Fugitive Source Identification and Data Collection..............31 

 3.2.2 Landfill Emission Estimation Methodology ..........................31 

4.0 Area Sources............................................................................................33 

 4.1 Source Identification ......................................................................33 

 4.1.1 Evaporative Emissions (VOM) ............................................33 

 4.1.2 Combustion Emissions (CO, NOx, VOM)............................34 

 4.1.3 Excluded Categories...........................................................34 

 4.2 Emission Estimation Methods........................................................35 

 4.2.1 Sources of Data ..................................................................35 

 4.2.2 Rule Effectiveness and Rule Penetration............................36 

 4.2.3 Double Counting of Emissions ............................................36 

 4.2.4 Annual Emissions to Daily Emissions Calculation...............37 

 4.2.5 Estimating Emissions at the Township Level ......................37 

 4.3 Categorical Emission Summary.....................................................38 

 4.3.1 Agricultural Pesticide Application ........................................38 

 4.3.2 Aircraft Refueling.................................................................39 

 4.3.3 Architectural Coatings.........................................................40 

 4.3.4 Asphalt Paving ....................................................................41 

 4.3.5 Automobile Refinishing .......................................................42 

i 
Section Page

 4.3.6 Commercial Cooking...........................................................44 

 4.3.7 Consumer Solvent Use .......................................................46 

 4.3.8 Dry Cleaning .......................................................................47 

 4.3.9 Forest Fires.........................................................................48 

 4.3.10 Fuel Combustion – Commercial/Institutional.......................49 

 4.3.11 Fuel Combustion – Industrial ..............................................53 

 4.3.12 Fuel Combustion – Residential ...........................................55 

 4.3.13 Gasoline Marketing .............................................................62 

 4.3.14 Graphic Arts ........................................................................68 

 4.3.15 Incineration .........................................................................69 

 4.3.16 Industrial Surface Coating...................................................70 

 4.3.17 Marine Vessel VOL Loading and Transport ........................72 

 4.3.18 Open Burning......................................................................73 

 4.3.19 Pavement Markings ............................................................77 

 4.3.20 Portable Fuel Containers ....................................................78 

 4.3.21 Solvent Cleaning.................................................................81 

 4.3.22 Structure Fires.....................................................................82 

 4.3.23 Waste Water Treatment ......................................................83 

 4.3.24 Biogenic Emissions.............................................................86 

5.0 Mobile Sources.........................................................................................87 

 5.0.1 Categories of Mobile Sources .............................................87 

 5.0.2 Categories and Components of Mobile Source 

 Emissions............................................................................88 

 5.1 On-Highway Mobile Source Inventory ...........................................89 

 5.1.1 On-Highway Mobile Source Emissions Summary...............89 

 5.1.2 Inventory Guidance and References...................................90 

 5.1.3 Basic Concepts of On-Highway Mobile Source 

Emission Inventories...........................................................92 

 5.1.4 Calculation of Daily Emissions ..........................................107 

 5.1.5 Calculation of Annual Emissions .......................................109 

 5.2 Off-Highway Mobile Source Emissions........................................110 

 5.2.1 Estimating Off-Highway Emissions ...................................110 

 5.2.2 Off-Highway Modes of Transportation...............................110 

6.0 Quality Assurance ..................................................................................127 

 6.1 Purpose of the Inventory..............................................................127 

 6.2 Scope of the Quality Assurance Plan ..........................................127 

 6.3 Summary of QA Activities ............................................................127 

 6.3.1 Inventory and QA Planning ...............................................128 

 6.3.2 Resource Allocation for QA...............................................128 

 6.3.3 Schedule and Project Planning .........................................128 

ii 
Section Page

 6.4 QA Technical Information ............................................................129 

 6.4.1 Prioritizing Sources and Data Elements............................129 

 6.4.2 Data Sources and Checking Procedures ..........................130 

 6.5 Data Collection and Analysis .......................................................131 

 6.5.1 Identification of Emission Sources ....................................131 

 6.5.2 Data Quality ......................................................................132 

 6.5.3 Emission Estimation Methods ...........................................133 

 6.5.4 Consistency with Other States ..........................................133 

 6.5.5 Calculations and Data Handling........................................134 

 6.5.6 Validation Procedures .......................................................134 

 6.6 Data Handling ..............................................................................135 

 6.6.1 Data Coding and Recording..............................................135 

 6.6.2 Data Tracking....................................................................135 

 6.6.3 Correcting Data.................................................................135 

 6.6.4 Missing Data .....................................................................135 

 6.7 QA Audits.....................................................................................136 

 6.7.1 Internal ..............................................................................136 

 6.7.2 External.............................................................................137 

7.0 Conclusion..............................................................................................139 

8.0 References .............................................................................................141 

Appendices 

 A 2002 Illinois Statewide Emissions by Category............................A-1 

 B 2002 Illinois Chicago NAA Emissions by Category......................B-1 

 C 2002 Illinois Metro-East NAA Emissions by Category..................C-1 

 D 2002 Illinois Attainment Area Emissions by Category..................D-1 

 E 2002 Illinois County Level Emissions...........................................E-1 

 F Nonattainment Township Surrogates and Apportionment ........... F-1 

 G Sample County Level Activity Data..............................................G-1 

iii 
List of Tables 

Number Page

2-1 Total Ozone Inventory Typical Summer Day Emissions.............................9 

2-2 Total Ozone Inventory Annual Emissions.................................................10 

2-3 Geographic Contributions.........................................................................17 

2-4 Statewide Emission Contributions ............................................................17 

2-5 Chicago NAA Emission Contributions ......................................................17 

2-6 Metro-East NAA Emission Contributions ..................................................18 

2-7 Attainment Area Emission Contributions ..................................................18 

3-1 Point Source Emissions............................................................................32 

4-1 Agricultural Pesticide Active Ingredient per Acre Factors .........................38 

4-2 Agricultural Pesticide Application Emissions ............................................39 

4-3 Aircraft Refueling Emissions.....................................................................40 

4-4 Architectural Coating Emissions ...............................................................41 

4-5 Asphalt Paving Emissions ........................................................................42 

4-6 Automobile Refinishing Emissions............................................................43 

4-7 Percent of Restaurants with Each Type of Cooking Equipment ...............44 

4-8 Average Number of Equipment Pieces by Restaurant Type ....................44 

4-9 Average Pounds of Meat Cooked on Each Type of Equipment................45 

4-10 Commercial Cooking Emission Factors....................................................45 

4-11 Commercial Cooking Emissions ...............................................................46 

4-12 Consumer Solvent Use Emission Factors ................................................46 

4-13 Consumer Solvent Use Emissions ...........................................................47 

4-14 Dry Cleaning Emissions ...........................................................................48 

4-15 Forest Fire Emission Factors....................................................................49 

4-16 Forest Fire Emissions...............................................................................49 

4-17 Commercial/Institutional Fuel Combustion Emission Factors...................50 

4-18 Commercial/Institutional Natural Gas Combustion Emissions..................51 

4-19 Commercial/Institutional Distillate Oil Combustion Emissions ..................51 

4-20 Commercial/Institutional Residual Oil Combustion Emissions..................52 

4-21 Commercial/Institutional Kerosene Combustion Emissions......................52 

4-22 Commercial/Institutional LPG Combustion Emissions..............................53 

4-23 Industrial Fuel Combustion Emission Factors...........................................54 

4-24 Industrial Natural Gas Combustion Emissions..........................................54 

4-25 Industrial Distillate Oil Combustion Emissions..........................................55 

4-26 Industrial Residual Oil Combustion Emissions .........................................55 

4-27 Residential Fuel Combustion Emission Factors other than Wood............56 

4-28 Statewide Residential Fuel Combustion Fuel Use....................................56 

4-29 Residential Natural Gas Combustion Emissions ......................................57 

4-30 Residential Distillate Oil Combustion Emissions.......................................57 

4-31 Residential Kerosene Combustion Emissions ..........................................58 

4-32 Residential LPG Combustion Emissions ..................................................58 

4-33 Residential Coal Combustion Emissions ..................................................59 

iv 
Number Page

4-34 Application of American Housing Survey..................................................60 

4-35 Residential Wood Combustion Emission Factors.....................................61 

4-36 Residential Wood Combustion Fireplace Emissions ................................62 

4-37 Residential Wood Combustion Wood Stove Emissions............................62 

4-38 Stage I Emissions.....................................................................................63 

4-39 Stage II Emission Factors.........................................................................64 

4-40 Stage II Emissions....................................................................................65 

4-41 Tank Truck Leak Emission Factors ..........................................................66 

4-42 Gasoline Tank Truck Leak Emissions ......................................................66 

4-43 Underground Storage Tank Breathing Emission Factors .........................67 

4-44 Underground Storage Tank Breathing Emissions.....................................67 

4-45 Graphic Arts Emissions ............................................................................68 

4-46 Incineration Emission Factors...................................................................69 

4-47 Industrial/Commercial/Institutional Incineration Emissions .......................70 

4-48 Industrial Surface Coating Emission Factors............................................71 

4-49 Industrial Surface Coating Emissions .......................................................72 

4-50 Marine Vessel VOL Loading and Transport Emissions ............................73 

4-51 Prescribed Burning Emission Factors.......................................................74 

4-52 Prescribed Burning Emissions..................................................................74 

4-53 Residential Household Waste Combustion Emission Factors ..................75 

4-54 Residential Household Waste Combustion Emissions .............................76 

4-55 Yard Waste Combustion Emission Factors ..............................................76 

4-56 Yard Waste Combustion Emissions .........................................................77 

4-57 Pavement Marking Emissions ..................................................................78 

4-58 Commercial Portable Fuel Container VOM Emission Factors ..................79 

4-59 Commercial Portable Fuel Container Emissions ......................................80 

4-60 Residential Portable Fuel Container Emission Factors.............................80 

4-61 Residential Portable Fuel Container Emissions........................................81 

4-62 Solvent Cleaning Emission Factors..........................................................82 

4-63 Solvent Cleaning Emissions .....................................................................82 

4-64 Structure Fire Emission Factors ...............................................................83 

4-65 Structure Fire Emissions ..........................................................................83 

4-66 POTW Emissions .....................................................................................85 

4-67 Industrial Waste Water Treatment Emissions...........................................85 

4-68 Biogenic Emissions ..................................................................................86 

5-1 On-Road Mobile Source Emissions..........................................................90 

5-2 Inventory Vehicle Types in MOBILE6 .......................................................92 

5-3 HPMS Functional Classes of Roads and Their Codes .............................93 

5-4 MOBILE6 Facility Types or Driving Cycles ...............................................94 

5-5 Statewide Average VMT Mixes.................................................................97 

5-6 Summary of ADVMT...............................................................................100 

5-7 Weekday Seasonal Division Factors for Application to Weekday...........103 

v 
Number Page

5-8 Monthly Factors to Convert ADVMT to Total Monthly VMT ....................104 

5-9 MOBILE6.2 Inputs Used in this Inventory to Evaluate Summer 

Weekday Emission Factors ....................................................................105 

5-10 Specialized MOBILE6 Inputs for Summer Weekday Refueling 

Emission Factors....................................................................................106 

5-11 I/M Fraction for Illinois Counties .............................................................109 

5-12 Statewide Facility Type Fractions ...........................................................110 

5-13 Railroad Locomotive Emissions..............................................................111 

5-14 Aircraft Emissions...................................................................................112 

5-15 Fleetwide Emission Factors....................................................................119 

5-16 EDMS Emission Factors for Military Aircraft Based in Illinois .................120 

5-17 Emissions from APUs.............................................................................121 

5-18 Commercial Marine Vessel Emissions ...................................................124 

5-19 NONROAD Input Parameters for Summer Daily Emissions...................125 

5-20 NONROAD Input Parameters for Annual Emissions ..............................126 

5-21 Off-road Engine Emissions.....................................................................126 

6-1 Potential Sources with 2002 Emissions not being Representative .........137 

6-2 Sources Making Comments on Data Sent to IERG................................138 

7-1 Emission Summary (tons/day)................................................................139 

7-2 Emission Summary (tons/year)...............................................................139 

7-3 Statewide Emission Contributions ..........................................................139 

7-4 Chicago NAA Emission Contributions ....................................................140 

7-5 Metro-East NAA Emission Contributions ................................................140 

7-6 Attainment Area Emission Contributions ................................................140 

7-7 Geographic Contributions.......................................................................140 

A-1 Statewide Emissions ..............................................................................A-1 

B-1 Chicago NAA Emissions.........................................................................B-1 

C-1 Metro-East NAA Emissions ....................................................................C-1 

D-1 Attainment Area Emissions ....................................................................D-1 

E-1 County Level CO Emissions...................................................................E-1 

E-2 County Level NOx Emissions .................................................................E-6 

E-3 County Level VOM Emissions ..............................................................E-11 

F-1 Nonattainment Township Surrogates and Apportionment ...................... F-1 

G-1 County Level Activity Data......................................................................G-1 

G-2 County Level Commercial/Institutional Fuel Use ....................................G-4 

G-3 County Level Industrial Fuel Use............................................................G-7 

G-4 County Level Residential Fuel Use.......................................................G-10 

G-5 Average Daily Vehicle Miles of Travel by County and HPMS 

Functional Class...................................................................................G-13 

G-6 Average Summer Weekday Vehicle Miles of Travel by County 

and HPMS Functional Class.................................................................G-16 

G-7 Monthly VMT by County .......................................................................G-19 

G-8 Aircraft Operations................................................................................G-22 

vi 
List of Figures 

Number Page

2-1 Daily CO Emission Summary ...................................................................11 

2-2 Annual CO Emission Summary ................................................................12 

2-3 Daily NOx Emission Summary..................................................................13 

2-4 Annual NOx Emission Summary ..............................................................14 

2-5 Daily VOM Emission Summary.................................................................15 

2-6 Annual VOM Emission Summary .............................................................16 

2-7 Statewide Geographic Contributions of Ozone Precursor 

Daily Emissions ........................................................................................19 

2-8 Statewide Geographic Contributions of Ozone Precursor 

Annual Emissions .....................................................................................20 

2-9 Chicago NAA Ozone Precursor Daily Emissions......................................21 

2-10 Chicago NAA Ozone Precursor Annual Emissions...................................22 

2-11 Metro-East NAA Ozone Precursor Daily Emissions .................................23 

2-12 Metro-East NAA Ozone Precursor Annual Emissions ..............................24 

2-13 Attainment Area Ozone Precursor Daily Emissions..................................25 

2-14 Attainment Area Ozone Precursor Annual Emissions ..............................26 

2-15 Statewide Ozone Precursor Daily Emissions ...........................................27 

2-16 Statewide Ozone Precursor Annual Emissions ........................................28 

vii 
List of Acronyms 

ADT Average Daily Traffic 

ADVMT Average Daily Vehicle Miles Traveled 

AER Annual Emission Report 

AFB Air Force Base 

AP-42 Compilation of Air Pollutant Emission Factors 

APU Auxiliary Power Unit 

ASWVMT Average Summer Weekday Vehicle Miles Traveled 

BIOME3 Biogenic Model for Emissions (version 3.0) 

CAA Clean Air Act Amendments of 1990 

CAERS Computerized Annual Emission Reporting System 

CATS Chicago Area Transportation Study 

CERR Consolidate Emissions Reporting Rule 

C/I Commercial/Institutional 

CMV Commercial Marine Vessel 

CNG Compressed Natural Gas 

CO Carbon Monoxide 

CTG Control Technique Guideline 

DVMT Daily Vehicle Miles Traveled 

EDMS Environmental Data Management System 

EGAS Economic and Growth Analysis System 

EIA Energy Information Administration 

EWGCC East-West Gateway Coordinating Council 

FAA Federal Aviation Administration 

FC Functional Classes 

FHWA Federal Highway Administration 

FT Facility Type 

HC Hydrocarbon 

HPMS Highway Performance Monitoring System 

IC Internal Combustion 

ICEMAN Integrated Comprehensive Environmental Management System 

IDOT Illinois Department of Transportation 

IEPA Illinois Environmental Protection Agency 

IERG Illinois Environmental Regulatory Group 

IDS Inventory and Data Support Unit 

I/M Inspection and Maintenance 

ISSIS Illinois EPA’s Illinois’ Stationary Source Inventory System 

IWTF Industrial Wastewater Treatment Facility 

LADCO Lake Michigan Air Directors Consortium 

LPG Liquefied Petroleum Gas 

LTO Landing and Takeoff Operation 

MPO Metropolitan Planning Organization 

MRI Midwest Research Institute 

NAA Nonattainment Area 

NAAQS National Ambient Air Quality Standard 

viii 
NAICS North American Industrial Classification System 

NOx Oxides of Nitrogen 

OAQPS USEPA Office of Air Quality Planning and Standards 

OBVR On-board Vapor Recovery 

POTW Publicly-owned Treatment Works 

PUA Public Use Airport 

QA Quality Assurance 

QC Quality Control 

RE Rule Effectiveness 

ROP Rate of Progress 

RP Rule Penetration 

RVP Reid Vapor Pressure 

SCC Source Classification Code 

SIC Standard Industrial Classification (code) 

SIP State Implementation Plan 

SOCMI Synthetic Organic Chemical Manufacturing Industry 

THC Total Hydrocarbons 

TIM Time In Mode 

TPD Tons per Day 

TPY Tons per Year 

TSDF Hazardous Waste Treatment, Storage and Disposal Facility 

USEPA US Environmental Protection Agency 

VMT Vehicle Miles Traveled 

VOL Volatile Organic Liquid(s) 

VOM Volatile Organic Material 

ix 

Executive Summary 

The 1990 Clean Air Act Amendments (CAA) requires all states to revise and submit 

State Implementation Plans (SIPs) for areas in nonattainment of the National Ambient 

Air Quality Standards (NAAQS) for ozone. On June 15, 2004, USEPA designated two 

areas of the state in nonattainment for the 8-hour ozone standard. The Chicago area 

matches the nonattainment area from the previous 1-hour ozone standard. The MetroEast nonattainment area includes the three counties from the 1-hour standard 

(Madison, Monroe and St. Clair) plus Jersey County. Both areas are identified as 

moderate ozone nonattainment areas. 

As part of the designation of nonattainment areas for the 8-hour ozone standard, a new 

attainment demonstration SIP will be necessary. A key element in the overall SIP 

planning process is the need for an updated emission inventory. This document is the 

description of the methods used to compile the 2002 base year inventory for ozone. It 

includes CO, NOx and VOM emissions for point, area, on-road mobile, off-road mobile 

and biogenic emissions for the entire State of Illinois. 

The primary source of data for point sources was the source-reported 2002 annual 

emission reports (AERs). Area source emissions are typically estimated by multiplying 

an emission factor by a known indicator of activity (e.g., population) for a source 

category. On-road mobile source emissions were calculated using the MOBILE6 

computer model. Off-road mobile source emissions were calculated using the 

NONROAD model. Biogenic emissions, those from vegetation, were obtained from 

USEPA’s running of the BEIS model. 

To ensure this inventory is of the highest quality, Illinois EPA implemented quality 

assurance (QA) procedures and quality control (QC) checks throughout the inventory 

process. Illinois EPA specifically followed the procedures outlined in USEPA’s guidance 

documents pertaining to inventory quality assurance and therefore believes the 

inventory to be complete, accurate and of high quality. 

xi 
1 Introduction 

Title I of the 1990 Clean Air Act Amendments (CAA) requires all states to revise and 

submit State Implementation Plans (SIPs) addressing Title I requirements for areas in 

nonattainment for the National Ambient Air Quality Standards (NAAQS) for ozone. The 

Chicago and Metro-East St. Louis (Metro-East) areas are currently designated as 

moderate nonattainment areas (NAAs) for the 8-hour ozone standard. 

The Chicago NAA includes the counties of Cook, DuPage, Kane, Lake, McHenry and 

Will, plus the Townships of Aux Sable and Goose Lake in Grundy County and Oswego 

Township in Kendall County. The Metro-East NAA includes the counties of Jersey, 

Madison, Monroe and St. Clair. The USEPA designated these areas as nonattainment 

for the 8-hour ozone standard on June 15, 2004. 

The primary source of data for point sources was the source-reported 2002 annual 

emission reports (AERs). Area source emissions are typically estimated by multiplying 

an emission factor by a known indicator of activity (e.g., population) for a source 

category. Calculation of emissions for area sources used 2002 category activity levels 

or in some cases, projections from previous years. Area source calculation 

methodologies were updated to the most recent calculation methods identified by 

USEPA. 

On-road mobile source emissions were estimated by multiplying appropriate emission 

factors generated from the MOBILE6 computer model by vehicle miles traveled. Illinois 

EPA relied on 2002 VMT data generated by the Illinois Department of Transportation 

Office of Planning and Programming. 

Off-road mobile source emissions were calculated using the NONROAD computer 

model. This model outputs emissions directly. The NONROAD model does not 

included emission estimates for aircraft, locomotives and commercial marine vessels. 

Aircraft emissions were calculated using actual activity data (operations) for each 

airport. Emissions from locomotives and commercial marine vessels were obtained 

from LADCO who funded a study with Environ to obtain these emissions and describe 

the calculation methodology. 

Biogenic emissions, those from vegetation such as trees, shrubs, crops and other 

plants, were obtained from USEPA who used the Biogenic Emission Inventory System 

(BEIS). This data was compiled by USEPA and made available to the States for their 

optional use. 

To ensure this inventory is of the highest quality, Illinois EPA implemented quality 

assurance (QA) procedures and quality control (QC) checks throughout the inventory 

process. Illinois EPA specifically followed the procedures outlined in USEPA’s guidance 

1 

2 Emission Inventory Summaries 

2.1 Background 

This document presents the 2002 base year emission inventory for reactive CO, oxides 

of nitrogen (NOx) and VOM from point, area, biogenic and mobile sources for the State 

of Illinois. This inventory includes the ozone NAAs of Chicago and Metro-East St. Louis 

as well as those counties that are in attainment with the 8-hour NAAQS for ozone. 

Four basic steps were involved in the preparation of the emission inventory. The first 

step was planning. As required by USEPA guidance, Illinois EPA prepared an Inventory 

Preparation Plan (IPP). This plan outlined the methods by which the Illinois EPA would 

assemble the 2002 inventory and perform QA/QC checks. The QA/QC plans and 

procedures are presented in Section 6.0. 

The second basic step was data collection. A major element in this step was to 

determine which source categories should be considered as point sources in the 

inventory and which should be considered area sources. Fundamentally different data 

collection procedures are used for these two source types. Actual emissions data 

reported in the sources’ AERs are used to collect point source data, whereas county 

level information is generally used to estimate area source activity. Much more detailed 

data are collected and maintained on point sources. 

The third basic step in the inventory compilation effort involved analysis of data 

collected and the development of emission estimates for each source. Emissions were 

determined individually for each point source, whereas emissions were generally 

determined for the overall area source category. Source emission data, material 

balances and emission factors were all used to make these estimates. Adjustments 

were made to the VOM inventory to reflect only reactive VOM and to be representative 

of the ozone season. 

The fourth step was reporting. Initially, Illinois EPA identified the kinds of data and 

formats that would be needed for this inventory document to fulfill USEPA inventory 

requirements. Later, Illinois EPA identified additional reports and features that would be 

useful for future inventory needs and/or modeling requirements. These have been 

incorporated into this document. 

Demographic data characterizing the various counties in the state are crucial to many of 

the emission estimation calculation procedures used to develop the inventory for area 

source categories. As such, these data are cited in the appropriate sections of Section 

4.0 – Area Sources. Also, in a number of instances, emissions are dependent to some 

degree on the geographic location of the county. In such instances, Illinois EPA 

developed factors based on whether counties were either a “Northern” or “Southern” 

county. Details of how the factors were developed and used are explained in detail in 

the appropriate area and mobile source sections of the document. 

3 
A number of agencies provided data for use in developing the Chicago and Metro-East 

nonattainment area inventories. The lead agency was the Illinois EPA which was 

directly responsible for coordinating and supervising the completion of each segment of 

the inventory. Several other state and local agencies contributed information to Illinois 

EPA that was necessary for preparing emission estimates. The majority of the highway 

vehicle emission calculation information was provided by IDOT. IDOT used federally 

approved transportation planning methods to develop VMT estimates which were based 

on monitored traffic count data in selected key locations throughout the state, including 

the Chicago area. Certain other localized traffic data were obtained from CATS for the 

Chicago ozone nonattainment area and the East-West Gateway Coordinating Council 

for the Metro-East ozone nonattainment area. 

2.2 Methodology 

A detailed emission inventory for a pollutant lists each source of that pollutant and the 

quantity of its emissions. The sources are usually categorized in two ways: (1) point, 

area or mobile sources or (2) industrial categories and subcategories. 

Emissions from point sources are defined as those whose emissions are usually fairly 

well characterized and are generally discharged through stacks and which are required 

to possess an Illinois EPA issued permit. Fugitive emissions are not emitted from a 

discrete point but are emitted from numerous areas throughout a facility. Area sources 

are usually spread over wide areas with no distinct discharge points (e.g., a road or 

large parking lot) or are comprised of a large number of small point sources that are 

difficult to describe separately (e.g., the heating furnaces in individual homes in a city) 

and whose emissions are not so well characterized. Other examples of area sources 

include architectural surface coating, automobile refueling, dry cleaning and automobile 

refinishing. Mobile sources are divided into two major categories – on-road and offroad. On-road mobile sources included cars, trucks, buses and motorcycles used for 

transportation of goods and passengers on roads and streets. Off-road mobile sources 

include other modes of powered transportation such as aircraft, trains, ships and motor 

vehicles used off-highway. This classification protocol has been utilized throughout this 

document. 

A typical industrial plant may have different source types associated with it. For 

example, a refinery with numerous industrial processes would itself be a point source, 

the leaks from valves, pumps and fittings throughout the miles of piping would be a 

fugitive source and the switch engine that moves tank cars on the railroad siding would 

be a non-highway mobile source. Also, a plant may have more than one industrial 

classification associated with it. The refinery in the previous example is in one industrial 

category; its tank farm is in another. Quantities of emissions may be measured directly 

(at the stack); they may be calculated from engineering principles (e.g., mass balance); 

or they may be estimated (e.g., by assuming reasonable emission rates, times, etc.). 

Further, emissions can be expressed in terms of annual emissions, seasonal emissions 

4 
or daily emissions. In the case of the pollutant ozone, precursor emissions are 

generally expressed in terms of typical daily emissions representative of the peak ozone 

season, or tons per day. 

Emission estimates presented in this report generally followed the methodologies 

outlined in USEPA’s emission inventory preparation guidance document (Reference 3), 

Volumes I-IV and USEPA’s “Reporting Guidance for 1996 Periodic Emissions 

Inventories and National Emission Trends (NET) Inventories.” Where different 

estimation methodologies were used, such methods are identified. The emission 

estimates were seasonally adjusted to reflect average daily emissions during the 

summer months, which are generally considered the peak ozone season. For point 

sources, emissions were taken from source submitted data for the peak ozone season, 

as reported in their 2002 AERs. Mobile source emissions and certain area source 

emissions (e.g., gasoline refueling) were adjusted using the average ambient 

temperature during the ten highest ozone days during 2002. Area source emissions 

were also modified using seasonal adjustment factors for the ozone season. Some 

sources have greater emissions on weekdays than on weekends. Emissions from all 

such sources have been adjusted to take weekday/weekend differences into 

consideration. In addition, adjustments were made to gasoline fuel-based categories to 

be representative of 2002 fuel volatility levels. Emission totals are expressed as 2002 

values using data for 2002, whenever available. 

The VOM emission estimates provided in this document are for those VOMs determined 

by USEPA to be photochemically reactive. All identified nonreactive VOMs were 

excluded from the VOM totals reported here for all sources and source categories. 

Compounds considered to be nonreactive and therefore not included in the inventory 

are listed below: 

• Methane 

• Ethane 

• Methylene chloride 

• Methyl chloroform 

• Trichlorofluoromethane (CFC-11) 

• Dichlorodifluoromethane (CFC-12) 

• Chlorodifluoromethane (CFC-22) 

• Trifluoromethane (HFC-23) 

• Chlorofluoromethance (HCFC-31) 

• Difluoromethane (HFC-32) 

• Decafluoropentane (HFC-43-10mee) 

• Ethylfluoride (HFC-161) 

• Trichlorotrifluoroethane (CFC-113) 

• Dichlorotetrafluoroethane (CFC-114) 

• Chloropentafluoroethane (CFC-115) 

• 2,2-Dichloro-1,1,1-trifluoroethane (HCFC-123) 

• 1,1,2-Trifluoroethane (HCFC-123a) 

5 
• 2-Chloro-1,1,1,2-tetrafluoroethane (HCFC-124) 

• Pentafluoroethane (HFC-125) 

• 1,1,2,2,-Tetrafluoroethane (HFC-134) 

• 1,1,1,2-Tetrafluoroethane (HFC-134a) 

• 1,1-Dichloro-1-fluoroethane (HCFC-141b) 

• 1-Chloro-1,1,-difluoroethane (HCFC-142b) 

• 1,1,1-Trifluoroethane (HFC-143a) 

• Fluoroethane (HCFC-151a) 

• 1,1-Difluoroethane (HFC-152a) 

• Pentafluoropropane (HFC-225ca) 

• Pentafluoropropane (HFC-225cb) 

• Hexafluoropropane (HFC-236ea) 

• Hexafluoropropane (HFC-236fa) 

• Pentafluoropropane (HFC-245ca) 

• Pentafluoropropane (HFC-245ea) 

• Pentafluoropropane (HFC-245eb) 

• Pentafluoropropane (HFC-245fa) 

• Pentafluorobutane (HFC-365mfc) 

• Parachlorobenzotrifluoride (PCBTF) 

• Methoxybutane 

• Nonaflourobutane 

• Heptafluoropropane ((CF3)2CFCF2OCH3) 

• Heptafluoropropane ((CF3)CFCF2OC2H5) 

• Perchloroethylene 

• Cyclic, branched or linear completely methylated siloxanes 

• Methyl acetate 

• Volatile methyl siloxanes 

• Acetone 

Plus the following four classes of perfluorocarbons (PFCs) 

• Cyclic, branched or linear completely fluorinated alkanes 

• Cyclic, branched or linear completely fluorinated ethers with no unsaturations 

• Cyclic, branched or linear completely fluorinated tertiary amines with no 

unsaturations 

• Sulfur containing perfluorocarbons with no unsaturations and with sulfur 

bonds only to carbon and fluorine 

6 
2.2.1 Point Sources 

Emissions and source specific data for point sources were developed for the 2002 

inventory by Illinois EPA. The primary source of data for point sources was sourcereported AERs and permit files. These data are reported by the sources annually as 

part of the inventory process conducted by Illinois EPA and include emissions, process 

rates, operating schedules, emission control data and other relevant information 

obtained from the permit files and plant inspections. The data was converted to an 

Access® database for processing and retrieval. Emissions were computed on a typical 

daily ozone season basis for each point source process using the original data. This 

data was then updated based on the Illinois EPA’s QA/QC plan. 

2.2.2 Area Sources 

Area source emissions were typically estimated by multiplying an emission factor by a 

known indicator of activity for each source category and each county. Area source 

emissions for 2002 were based on data available for population, employment and 

commodities and were generally prepared following the procedures described in the 

Inventory Preparation Plans. Emission estimates for 2002 emissions were developed 

using 2002 category activity levels where available, or projections of changes in activity 

from 1990 levels. Emission controls were accounted for by using either adjusted 

emission factors or through the use of control factors. 

The narrative in Section 4.0 includes a discussion of the factors used to develop both 

the Chicago and Metro-East NAA emission estimates. Category summary tables 

reflecting Chicago and Metro-East NAA county emissions are also included. Although 

the methodologies used to determine attainment county emission estimates are similar, 

the factors will vary by county. Tables containing sample county activity data are 

included in Appendix G. 

2.2.3 Mobile Sources 

Statewide highway vehicle emissions were estimated by multiplying USEPA emission 

factors generated from the MOBILE6 computer model by daily VMT estimates by county 

for the two Illinois nonattainment areas and the attainment counties. Illinois EPA relied 

on VMT data generated by the IDOT Office of Planning and Programming. IDOT used 

urban transportation planning methodologies approved by the Federal Highway 

Administration to generate the necessary VMT estimates. Illinois EPA ran the 

MOBILE6 model to generate vehicle emission rates and calculate emission estimates. 

Chicago and Metro-East nonattainment area specific data were used whenever possible 

to estimate inputs into the MOBILE6 model. For some parameters, however, sufficient 

resources were not available for Illinois EPA to develop area-specific values, so national 

average defaults contained in the model were used. For discussion of the inputs used 

in running MOBILE6 is included in Section 5.0. 

7 
8 

Emissions were also estimated for non-road equipment. Illinois EPA prepared ozone 

precursor emission estimates for railroad locomotives; commercial, military and civil 

aircraft; and commercial vessels using state- and county-specific activity factors and 

USEPA approved emission factors. Also included were emission estimates for nine 

other categories of non-road equipment. These estimates were prepared by USEPA 

and were supplied to states for use in ozone and CO emission inventories. Further 

discussion of non-road equipment emission estimation methodologies and actual 

estimates are contained in Section 5.2. 

2.3 Results 

The 2002 Base Year Emission Inventory summary of the total ozone precursor emission 

estimates for the State of Illinois is shown in Tables 2-1 and 2-2. It covers the entire 

state and includes both anthropogenic (man-caused) and biogenic (vegetationproduced) emissions. 

The magnitude of the total CO, NOx and VOM emissions for the state by geographic 

region are delineated in the bar charts of Figures 2-1 through 2-6. The percentage 

contributions of the individual regions to the statewide total are shown in Figures 2-7 

and 2-8. The pie charts of Figures 2-9 through 2-16 present the total ozone precursor 

emissions by each geographic region of the state. 

Category summaries by pollutant for the 2002 statewide inventory are given in 

Appendices A through D. Appendix E presents a county-by-county summary of point, 

area, on-road and off-road emissions. Appendix F includes the surrogates used to 

apportion area source emissions to the nonattainment townships (portions of counties). 

Appendix G identifies sample activity data by county. 
Table 2-1: Total Ozone Inventory Typical Summer Day Emissions (tons/day) 

Point Area On-Road Off-Road Biogenic 

Chicago NAA 

 CO 

 NOx 

 VOM 

154.80307.73

76.62

19.8542.93

273.33

2,076.43

408.88168.63

2,605.23

326.65233.77

23.7

6.8

236.7

Metro-East NAA 

 CO 

 NOx 

 VOM 

66.2154.2417.47

1.411.40

29.85

281.01

47.0723.57

148.94

36.7812.04

16.5

4.9

135.6

Attainment Area 

 CO 

 NOx 

 VOM 

239.41788.04230.59

12.0216.74

377.80

2,348.05

404.31203.12

1,193.30

480.67117.05

396.4147.0

2,653.7

Statewide 

 CO 

 NOx 

 VOM 

460.41

1,150.01

324.67

33.2861.07

680.98

4,705.48

860.26395.32

3,947.47

844.10362.87

436.7158.8

3,026.0

9 
Table 2-2: Total Ozone Inventory Annual Emissions (tons/year) 

Point Area On-Road Off-Road Biogenic 

Chicago NAA 

 CO 

 NOx 

 VOM 

25,632.1354,049.6221,190.70

34,239.4832,325.0689,090.21

979,219.14167,619.73

59,599.97

588,169.79

87,426.2453,272.30

4,188.41,682.5

38,667.6

Metro-East NAA 

 CO 

 NOx 

 VOM 

18,493.1612,057.17

4,775.20

6,582.451,881.19

13,787.68

119,743.24

16,983.38

8,445.99

29,438.72

8,050.032,978.95

3,214.61,207.2

24,741.8

Attainment Area 

 CO 

 NOx 

 VOM 

47,759.80

201,707.03

50,718.70

53,294.6813,229.30

119,512.33

1,066,794.52

125,265.82

75,449.84

266,993.57113,885.45

36,357.88

72,056.635,883.2

465,173.7

Statewide 

 CO 

 NOx 

 VOM 

91,885.09

267,813.83

76,684.60

94,116.6147,435.56

222,390.22

2,165,756.89

309,868.93143,495.81

884,602.08209,361.72

92,609.13

79,459.738,772.9

528,583.2

10 
Figure 2-1: Daily CO Emission Summary (tons/day) 

0

2,0004,0006,0008,000

10,000

Chicago 154.8 19.85 2,076.43 2,605.23 23.74 4,88M e tro Ea st 66.21 1.41 281.01 148.94 16.56 514Atta inm e nt 239.41 12.02 2,348.05 1193.3 396.43 4,18Sta te w ide 460.41 33.28 4,705.48 3947.47 436.73 9,58

Point Are a On-Roa d Off-Roa d Bioge nic To

11 
Figure 2-2: Annual CO Emission Summary (tons/year) 

0

500,000

1,000,0001,500,0002,000,0002,500,0003,000,0003,500,000

Chicago 25,632.13 34,239.48 979,219.14 588,169.79 4,188.44 1,6M e tro Ea st 18,493.16 6,582.45 119,743.24 29,438.72 3,214.65 17Atta inm e nt 47,759.80 53,294.68 1,066,794.52 266,993.57 72,056.68 1,5Sta te w ide 91,885.09 94,116.61 2,165,756.89 884,602.08 79,459.76 3,3

Point Are a On-Roa d Off-Roa d Bioge nic 

12 
Figure 2-3: Daily NOx Emission Summary (tons/day) 

0

500

100015002000250030003500

Chicago 307.73 42.93 408.88 326.65 6.83 1,093.0M e tro Ea st 54.24 1.4 47.07 36.78 4.95 144.45Atta inm e nt 788.04 16.74 404.31 480.67 147.06 1,836.8Sta te w ide 1,150.01 61.07 860.26 844.1 158.84 3,074.2

Point Are a On-Roa d Off-Roa d Bioge nic Tota l

13 
Figure 2-4: Annual NOx Emission Summary (tons/year) 

0

100,000200,000300,000400,000500,000600,000700,000800,000900,000

Chicago 54,049.62 32,325.06 167,619.73 87,426.24 1,682.52 343M e tro Ea st 12,057.17 1,881.19 16,983.38 8,050.03 1,207.20 40,Atta inm e nt 201,707.03 13,229.30 125,265.82 113,885.45 35,883.20 489Sta te w ide 267,813.83 47,435.56 309,868.93 209,361.72 38,772.91 873

Point Are a On-Roa d Off-Roa d Bioge nic T

14 
Figure 2-5: Daily VOM Emission Summary (tons/day) 

0

1,0002,0003,0004,0005,000

Chicago 76.62 273.33 168.63 233.77 236.71 989.0M e tro Ea st 17.47 29.85 23.57 12.04 135.62 218.5Atta inm ent 230.59 377.8 203.12 117.05 2,653.75 3,582.Sta te w ide 324.67 680.98 395.32 362.87 3,026.08 4,789.

Point Area On-Roa d Off-Roa d Bioge nic Tota 

15 
16 

Figure 2-6: Annual VOM Emission Summary (tons/year) 

0

200,000400,000600,000800,000

1,000,0001,200,000

Chicago 21,190.70 89,090.21 59,599.97 53,272.30 38,667.67 26M e tro Ea st 4,775.20 13,787.68 8,445.99 2978.95 24,741.85 5Atta inm e nt 50,718.70 119,512.33 75,449.84 36,357.88 465,173.71 74Sta te w ide 76,684.60 222,390.22 143,495.81 92,609.13 528,583.23 1,0

Point Area Off-Roa d On-Roa d Bioge nic 
2.3.1 Statewide Emissions 

The statewide daily emissions of CO, NOx and VOM are 9583.38, 3074.28 and 4789.92 

tons/day respectively. The statewide annual emissions of CO, NOx and VOM are 

3315820.44, 873,252.94, and 1,063,762.98 tons/year respectively. The contribution by 

area of the states can be seen in Table 2-3. The contribution by source category can 

be seen in Table 2-4. 

Table 2-3: Geographic Contributions (percent) 

Area CO 

Daily 

CO 

Annual 

NOx 

Daily 

NOx 

Annual 

VOM 

Daily 

VOM 

Annual 

Chicago NAA 50.9 49.2 35.6 39.3 20.6 24.6 

Metro-East NAA 5.4 5.4 4.7 4.6 4.6 5.1 

Attainment Area 43.7 45.4 59.7 56.1 74.8 70.2 

Table 2-4: Statewide Emission Contributions (percent) 

Category CO 

Daily 

CO 

Annual 

NOx 

Daily 

NOx 

Annual 

VOM 

Daily 

VOM 

Annual 

Point 4.8 2.8 37.4 30.7 6.8 7.2 

Area 0.3 2.8 2.0 5.4 14.2 20.9 

On-Road 49.1 65.3 28.0 35.5 8.3 13.5 

Off-Road 41.2 26.7 27.5 24.0 7.6 8.7 

Biogenic 4.6 2.4 5.2 4.4 63.2 49.7 

2.3.2 Chicago NAA Emissions 

The Chicago NAA daily emissions of CO, NOx and VOM are 4880.04, 1093.01 and 

989.05 tons/day respectively. The Chicago NAA annual emissions of CO, NOx and 

VOM are 1,631,448.97, 343,103.17 and 261,820.84 tons/year respectively. The 

contribution by source category can be seen in Table 2-5. 

Table 2-5: Chicago NAA Emission Contributions (percent) 

Category CO 

Daily 

CO 

Annual 

NOx 

Daily 

NOx 

Annual 

VOM 

Daily 

VOM 

Annual 

Point 3.2 1.6 28.2 15.8 7.7 8.1 

Area 0.4 2.1 3.9 9.4 27.6 34.0 

On-Road 42.5 60.0 37.4 48.9 17.0 22.8 

Off-Road 53.4 36.1 29.9 25.5 23.6 20.3 

Biogenic 0.5 0.3 0.6 0.5 23.9 14.8 

17 
2.3.3 Metro-East NAA Emissions 

The Metro-East NAA daily emissions of CO, NOx and VOM are 514.13, 144.45 and 

218.55 tons/day respectively. The Metro-East NAA annual emissions of CO, NOx and 

VOM are 177,472.22, 40,178.97 and 54,729.68 tons/year respectively. The contribution 

by source category can be seen in Table 2-6. 

Table 2-6: Metro-East Emission Contributions (percent) 

Category CO 

Daily 

CO 

Annual 

NOx 

Daily 

NOx 

Annual 

VOM 

Daily 

VOM 

Annual 

Point 12.9 12.2 37.6 30.0 8.0 8.7 

Area 0.3 4.4 1.0 4.7 13.7 25.2 

On-Road 54.7 79.2 32.6 42.3 10.8 15.4 

Off-Road 29.0 2.1 25.5 20.0 5.5 5.4 

Biogenic 3.2 2.1 3.4 3.0 62.1 45.2 

2.3.4 Attainment Area Emissions 

The Attainment Area daily emissions of CO, NOx and VOM are 4189.21, 1836.82 and 

3582.32 tons/day respectively. The Attainment Area annual emissions of CO, NOx and 

VOM are 1,506,899.25, 489,970.80 and 747,212.46 tons/year respectively. The 

contribution by source category can be seen in Table 2-7. 

Table 2-7: Attainment Area Emission Contributions (percent) 

Category CO 

Daily 

CO 

Annual 

NOx 

Daily 

NOx 

Annual 

VOM 

Daily 

VOM 

Annual 

Point 5.7 3.2 42.9 41.2 6.4 6.8 

Area 0.3 3.5 0.9 2.7 10.5 16.0 

On-Road 56.0 70.8 22.0 25.6 5.7 10.1 

Off-Road 28.5 17.7 26.2 23.2 3.3 4.9 

Biogenic 9.5 4.8 8.0 7.3 74.1 62.3 

18 
Figure 2-7: Statewide Geographic Contributions of Ozone Precursor Daily Emissions 

(tons/day) 

CO Emissions (9,583.38 tons/day)

Attainment Area

43.7%

Metro-East NAA

5.4%

Chicago NAA

50.9%

NOx Emissions (3,074.28 tons/day)

Attainment Area

59.7%

Metro-East NAA

4.7%

Chicago NAA

35.6%

VOM Emissions (4789.92 tons/day)

Attainment Area

74.8%

Metro-East NAA

4.6%

Chicago NAA

20.6%

19 
Figure 2-8: Statewide Geographic Contributions of Ozone Precursor Annual Emissions 

(tons/year) 

CO Emissions (3,315,820.44 tons/year)

Attainment Area

45.4%

Metro-East NAA

5.4%

Chicago NAA

49.2%

NOx Emissions (873,252.94 tons/year)

Attainment Area

56.1%

Metro-East NAA

4.6%

Chicago NAA

39.3%

VOM Emissions (1,063,762.98 tons/year)

Attainment Area

70.2%

Metro-East NAA

5.1%

Chicago NAA

24.6%

20 
Figure 2-9: Chicago NAA Ozone Precursor Daily Emissions (tons/day) 

CO Emissions (4,880.04 tons/day)

Biogenic

0.5%

Off-Road

53.4%

On-Road

42.5%

Area

0.4%

Point

3.2%

NOx Emissions (1,093.01 tons/day)

Biogenic

0.6%

Off-Road

29.9%

On-Road

37.4% Area

3.9%

Point

28.2%

VOM Emissions (989.05 tons/day)

Biogenic

23.9%

Off-Road

23.6%

On-Road

17.0%

Area

27.6%

Point

7.7%

21 
Figure 2-10: Chicago NAA Ozone Precursor Annual Emissions (tons/year) 

CO Emissions (1,631,448.97 tons/year)

Biogenic

0.3%

Off-Road

36.1%

On-Road

60.0%

Area

2.1%

Point

1.6%

NOx Emissions (343,103.17 tons/year)

Biogenic

0.5%

Off-Road

25.5%

On-Road

48.9% Area

9.4%

Point

15.8%

VOM Emissions (261,820.84 tons/year)

Biogenic

14.8%

Off-Road

20.3%

On-Road

22.8%

Area

34.0%

Point

8.1%

22 
Figure 2-11: Metro-East NAA Ozone Precursor Daily Emissions (tons/day) 

CO Emissions (514.13 tons/day)

Biogenic

3.2%

Off-Road

29.0%

On-Road

54.7%

Area

0.3%

Point

12.9%

NOx Emissions (144.45 tons/day)

Biogenic 3.4%

Off-Road 25.5%

On-Road 32.6%

Area 1.0% Point 37.6%

VOM Emissions (218.48 tons/day)

Biogenic 62.1%

Off-Road 5.5%

On-Road 10.8%

Area 13.7%

Point 8.0%

23 
Figure 2-12: Metro-East NAA Ozone Precursor Annual Emissions (tons/year) 

CO Emissions (177,472.22 tons/year)

Biogenic 2.1%

Off-Road 2.1%

On-Road 79.2%

Area 4.4%

Point 12.2%

NOx Emissions (40,178.97 tons/year)

Biogenic 3.0%

Off-Road 20.0%

On-Road 42.3%

Area 4.7% Point 30.0%

VOM Emissions (54,729.68 tons/year)

Biogenic 45.2%

Off-Road 5.4%

On-Road 15.4%

Area 25.2%

Point 8.7%

24 
Figure 2-13: Attainment Area Ozone Precursor Daily Emissions (tons/day) 

CO Emissions (4,189.21 tons/day)

Biogenic

9.5%

Off-Road

28.5%

On-Road

56.0%

Area

0.3%

Point

5.7%

NOx Emissions (1,836.82 tons/day)

Biogenic

8.0%

Off-Road

26.2%

On-Road

22.0%

Area

0.9%

Point

42.9%

VOM Emissions (3,582.32 tons/day)

Biogenic

74.1%

Off-Road

3.3% On-Road

5.7%

Area

10.5%

Point

6.4%

25 
Figure 2-14: Attainment Area Ozone Precursor Annual Emissions (tons/year) 

CO Emissions (1,506,899.25 tons/year)

Biogenic

4.8%

Off-Road

17.7%

On-Road

70.8%

Area

3.5%

Point

3.2%

NOx Emissions (489,970.80 tons/year)

Biogenic

7.3%

Off-Road

23.2%

On-Road

25.6%

Area

2.7% Point

41.2%

VOM Emissions (747,212.46 tons/year)

Biogenic

62.3%

Off-Road

4.9%

On-Road

10.1%

Area

16.0%

Point

6.8%

26 
Figure 2-15: Statewide Ozone Precursor Daily Emissions (tons/day) 

CO Emissions (9,583.38 tons/day)

Biogenic

4.6%

Off-Road

41.2%

On-Road

49.1%

Area

0.3%

Point

4.8%

NOx Emissions (3,074.28 tons/day)

Biogenic

5.2%

Off-Road

27.5%

On-Road

28.0%

Area

2.0% Point

37.4%

VOM Emissions (4,789.92 tons/day)

Biogenic

63.2%

Off-Road

7.6%

On-Road

8.3%

Area

14.2%

Point

6.8%

27 
Figure 2-16: Statewide Ozone Precursor Annual Emissions (tons/year) 

CO Emissions (3,315,820.44 tons/year)

Biogenic

2.4%

Off-Road

26.7%

On-Road

65.3%

Area

2.8%

Point

2.8%

NOx Emissions (873,252.94 tons/year)

Biogenic

4.4%

Off-Road

24.0%

On-Road

35.5%

Area

5.4%

Point

30.7%

VOM Emissions (1,063,762.98 tons/year)

Biogenic

49.7%

Off-Road

8.7%

On-Road

13.5%

Area

20.9%

Point

7.2%

28 
3 Point Sources 

A major distinction typically made in emission inventories is that between point and area 

sources. The Illinois EPA maintains detailed, unit-by-unit records of point sources 

based on permit applications and annual emission reports. This information is 

maintained for units emitting as little as 0.01 tons per year. Therefore, the 10 ton per 

year inventory requirement imposed by USEPA inventory guidance is more than 

adequately met for Illinois sources with permits. These units are the point source 

inventory. The area source inventory includes all other stationary sources not included 

in the point source inventory. In cases where the two categories overlap (e.g., fuel 

combustion and solvent use), care has been taken to not double-count emissions. A 

more detailed discussion of the area source inventory is provided in Section 4. 

The 2002 base year ozone point source inventory was prepared by the Illinois EPA 

using source reported data from AERs for all point sources in Illinois. Where necessary, 

the emissions have been adjusted for an average summer day at each emission unit 

within the source. In the rare instances where companies failed to submit an AER for 

2002, other data such as Illinois EPA estimates and previous annual emission reports 

were used. 

In addition to the Chicago and the Metro-East NAAs, the remaining counties, described 

as the attainment area, are included. The attainment area includes the portions of 

Grundy and Kendall Counties that are not within the Chicago NAA plus the remaining 

counties in Illinois not included in the two ozone nonattainment areas. 

The point source inventory described herein is considered to be the most current and 

accurate source of emission data available for 2002. 

3.1 Point Source Emissions 

The Illinois EPA defines point source process emissions as those which occur at an 

identifiable stationary stack or vent. Point source emissions not emitted from discrete 

stacks or vents are termed fugitive emissions and are discussed in Section 3.2. 

29 
3.1.1 Source Identification and Data Collection 

The sources to be included in the 2002 periodic inventory were identified using the 

Illinois EPA’s ICEMAN database. Facility production and emission data are included in 

this database. This information is facility-reported actual 2002 emissions. 

3.1.2 Non-reactive VOM Emission Adjustments 

The ICEMAN database is capable of identifying emissions of photochemically nonreactive VOM. This data in ICEMAN was used to specifically exclude those compounds 

from the 2002 base year ozone inventory. A complete list of the compounds that 

USEPA has identified as being photochemically non-reactive and which are excluded 

from the periodic inventory are listed in Section 2.2. 

3.1.3 Emission Estimation Methodologies 

Source reported actual emissions are used in the 2002 base year ozone inventory. 

Annual emission reports provided the ozone season hourly emissions and operating 

schedules that enabled the calculation of ozone season weekday emissions. Where 

operating schedules were missing or not required to be reported, Illinois EPA estimates 

were used. These estimates came from previously submitted annual emission reports 

or from permit applications. Typical emission estimation methodologies include material 

balance and emission factors. Schedules were adjusted for the ozone season based on 

summer throughput. 

3.2 Point Source Fugitive Emissions 

Another type of emission data which the Illinois EPA requires to be filed with the AER 

from point sources is fugitive emissions. Fugitive emissions are not released from a 

stack or a discrete point as are process emissions, but are emitted from an area. The 

ICEMAN database includes data on fugitive emissions from point sources so they are 

included in the point source inventory. 

30 
3.2.1 Fugitive Source Identification and Data Collection 

Fugitive emission point source categories included in the point source inventory are as 

follows: 

Petroleum Refineries 

• Fugitive Leaks 

• Wastewater Collection 

Synthetic Organic Chemical Manufacturing Industries (SOCMI) 

• Fugitive Leaks 

Iron and Steel Manufacture 

• Coke Oven Door Leaks 

• Hot and Cold Steel Rolling 

Waste Disposal 

• Municipal Landfills 

• Hazardous Waste Treatment, Storage and Disposal Facilities (TSDF) 

Many other fugitive-type emissions are included in the point source inventory, though 

they tend to be smaller than those listed above. For the most part, these emissions are 

due to the use of solvents (e.g., clean-up). These emissions can also be included in 

area source emissions so care has been taken to not double-count these emissions. 

3.2.2 Landfill Emission Estimation Methodology 

New regulations adopted in 1999 have made it more common for municipal waste 

landfills to have an operating permit for their air emissions. This means landfills are 

increasingly represented in the point source inventory. However, there are a few 

landfills without a permit that still need to be included in the inventory. The Bureau of 

Land’s Nonhazardous Solid Waste Management and Landfill Capacity Report1

 was 

used to obtain a listing of landfills in the state. This list was reviewed against the 

landfills identified in ICEMAN. 

Emissions were calculated for landfills included in the report but not in ICEMAN using 

methodology of Section 2.4 of AP-422

. Data on the date the landfill started accepting 

waste, amount of waste received, date the landfill started accepting waste, date the 

landfill closed (if applicable) and the type of landfill gas collection (if applicable) from 

Reference 1 was used to calculate emissions. 

31 
3.3 Point Source Emissions 

Table 3-1 includes the emissions from all sources classified as point sources. 

Table 3-1: Point Source Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 56.16 13,352.30 105.42 18,466.88 46.46 12,520.72 

DuPage 6.69 766.55 5.68 918.04 5.10 1,479.95 

Grundy Twps 29.63 1,376.89 32.08 2,874.71 3.39 982.53 

Kane 1.80 489.58 2.14 544.09 5.99 1,624.78 

Kendall Twps 0.43 91.95 1.30 180.63 0.31 118.89 

Lake 9.48 1,569.16 35.15 6,478.64 4.23 1,042.46 

McHenry 3.64 294.85 2.19 317.90 2.34 652.01 

Will 46.97 7,690.85 123.77 24,268.74 8.80 2,769.36 

Chicago NAA 154.80 25,632.13 307.73 54,049.62 76.62 21,190.70 

Jersey 0.00 0.74 0.00 0.00 0.04 18.55 

Madison 62.17 18,091.80 48.93 11,623.99 13.41 3,673.85 

Monroe 0.96 0.63 1.77 3.19 0.15 21.20 

St. Clair 3.07 399.99 3.54 429.99 3.88 1,061.60 

Metro-East NAA 66.21 18,493.16 54.24 12,057.17 17.47 4,775.20 

Attainment Area 239.41 47,759.80 788.04 201,707.03 230.59 50,718.70 

State Total 460.41 91,885.09 1,150.01 267,813.83 324.67 76,684.60 

32 
4 Area Sources 

Area sources are those activities for which aggregated source and emission information 

is maintained for entire source categories rather than for each individual source. The 

Illinois EPA is responsible for preparing the area source emission inventory. The area 

source inventory includes CO, NOx and reactive VOM for the entire state. Emission 

estimates are presented for the ozone nonattainment areas of Chicago and Metro-East 

St. Louis, as well as the remaining part of the state, which is in attainment with the 8-

hour ozone standard. Where no township-specific information was available for the 

Chicago NAA counties of Grundy and Kendall, apportioning factors were developed and 

applied to estimate area source activity. This is discussed further in Section 4.2.5. 

4.1 Source Identification 

Area source categories of CO, NOx and VOM emissions have been identified from the 

list of sources provided in Table 4.1-1 of the Procedures for the Preparation of Emission 

Inventories for Carbon Monoxide and Precursors of Ozone, Volume I: General 

Guidance for Stationary Sources3. These emission sources are divided into two groups 

characterized by the emission mechanism: evaporative emissions and fuel combustion 

emissions. Emissions of VOM have been estimated from both groups while CO and 

NOx emissions have been estimated only for fuel combustion categories. The 2002 

area source inventory includes the following source categories. 

4.1.1 Evaporative Emissions (VOM) 

Gasoline Distribution 

• Aircraft Refueling 

• Gasoline Tank Trucks in Transit 

• Portable Fuel Containers 

• Tank Truck Unloading (Stage I) 

• Underground Storage Tank Breathing 

• Vehicle Fueling (Stage II) 

Stationary Source Solvent Usage 

• Agricultural Pesticide Application 

• Architectural Surface Coating 

• Asphalt Paving 

• Automobile Refinishing 

• Commercial/Consumer Solvents 

• Dry Cleaning 

• Graphic Arts 

• Industrial Surface Coating 

• Pavement Markings 

33 
• Solvent Cleaning 

Volatile Organic Liquid (VOL) Transfer – Ship and Barge 

• Barge and Tanker Cleaning 

• Tanker Ballasting 

• VOL Loading Losses 

• VOL Transport 

Biogenics 

4.1.2 Combustion Emissions (CO, NOx, VOM) 

Fuel Combustion (natural gas, distillate, residual oil, kerosene, LPG, wood and coal) 

• Commercial/Institutional 

• Industrial 

• Residential 

Open Burning 

• Forest Wildfires 

• Prescribed Burning 

• Residential Household Waste 

• Yard Waste 

Waste Combustion 

• Commercial/Institutional 

• Residential 

Other 

• Commercial Cooking 

• Structure Fires 

4.1.3 Excluded Categories 

Previous periodic inventories have not included annual emissions, so some area 

categories (e.g., residential wood combustion) that did not emit in the summer months 

were excluded. Guidance from Reference 4 includes the reporting of annual emissions. 

All categories, whether or not they emit during the summer months, are included in the 

inventory. 

34 
Some area source categories continue to be excluded from the emission inventory. 

Lack of USEPA guidance, generally accepted inventory methodologies and lack of 

activity data are the main reasons for their exclusion. These categories are: 

• Leaking Underground Storage Tanks 

• Commercial Pesticide Use 

Care should also be taken when trying to identify area source categories that were not 

inventoried since the emissions may be included in the point source inventory. As 

stated previously, Illinois EPA’s point source inventory has a very low threshold of 

emission rates. This means that categories classified as area sources in other states 

are included in the point source inventory for Illinois. Categories falling into this 

category include: 

• Coal Combustion in Boilers 

• Drum/Barrel Operations 

• Flexible Polyurethane Foam Production 

• Industrial Adhesives 

• Oil and Gas Production 

• Pharmaceutical Manufacturing 

• Treatment, Storage and Disposal Facilities (TSDFs) 

4.2 Emission Estimation Methods 

Several methodologies have been used in estimating area source activity levels and 

emissions. 

• Applying local activity levels 

• Apportioning national or statewide activity levels to the local level 

• Using per capita emission factors 

• Using per employee emission factors 

• Data from inventories compiled by others 

4.2.1 Sources of Data 

Various sources have been used to determine activity/commodity level data and 

emission information for area source inventory purposes. Among these are the 

USEPA’s AP-42, UESPA’s FIRE emission factor database, and data from federal and 

state agencies including USEPA’s Office of Air Quality Planning and Standards, the US 

Department of Energy, US Bureau of Labor Statistics, Illinois Department of 

Transportation, Illinois Bureau of the Budget, Illinois Department of Conservation, Illinois 

Secretary of State, Illinois Department of Revenue and Illinois Department of 

Agriculture. 

35 
4.2.2 Rule Effectiveness and Rule Penetration 

For area sources subject to a VOM control equipment regulation, a rule effectiveness 

(RE) factor has been applied to the control efficiency when determining the emission 

rates. The RE adjustment reflects the assumption that regulations typically are not 100 

percent effective at all sources at all times. For example, if a RE factor of 95 percent 

has been assumed, a value of 0.95 is multiplied against the control efficiency before 

subtracting the efficiency from unity. 

In cases where a control regulation is applied to an area source category, a rule 

penetration (RP) adjustment may be required. The RP factor takes into account the fact 

that, due to exemptions within the rule, all sources within the category may not be 

regulated. Illinois EPA has used best judgment in the development and application of 

such factors. All assumptions have been documented. 

Due to the use of emission factors, rather than the independent calculation of 

uncontrolled emissions and subsequent control efficiencies, the use of RE and RP 

factors is limited. In addition, a number of rules regulating area source emissions deal 

with operational behavior (e.g., keeping the lid closed on a cold-cleaner) rather than the 

addition of control equipment. 

4.2.3 Double Counting of Emissions 

A major concern in the development of an area source inventory is the possibility of 

double-counting emissions. Because some area source methodologies estimate 

emissions from all sources within a category, emissions already contained in the point 

source inventory may also be included in the area source estimate. In these instances, 

the point source emissions must be subtracted from the gross area source estimate to 

determine the net area source estimate. Commonly affected area source categories 

are: 

• Dry Cleaning 

• Fuel Combustion 

• Graphic Arts 

• Incineration 

• Solvent Cleaning 

The methodologies described in Section 4.3 indicate when point source emissions were 

subtracted from the area source estimate. 

36 
4.2.4 Annual Emissions to Daily Emissions Calculation 

Emissions contained in this Section have been expressed using the format suggested 

by USEPA guidance (Reference 2). Activity levels and/or emission factors are 

frequently based on longer timeframes than a daily timeframe, so adjustment factors 

have been applied to estimate the typically summer weekday emissions. In order to 

determine the ozone season activity fraction, a seasonal adjustment factor is applied to 

the annual emission estimate. This factor, obtained from Reference 3 or other studies 

or analysis, compares the summer season percentage of annual activity for the specific 

category to a uniform seasonal activity level (25 percent). Therefore, if 30 percent of a 

certain activity occurs during the summer season, the seasonal adjustment factor would 

by 30 ÷ 25 or 1.2. 

In order to estimate emissions on a typical weekday, an activity adjustment factor is 

applied to the annual emission estimate. This factor is developed in one of two ways. 

First, the factor can be developed by dividing by the number of days per week an 

activity occurs and that total divided by 52, the number of weeks in the year. Therefore, 

the activity adjustment factor for an activity which occurs uniformly, seven days a week 

is calculated using the following equation: 1 ÷ 7 ÷ 52 = 0.00275. 

The second method is used when a percentage of work-week (Monday-Friday) activity 

has been developed. In this case, a work-week percentage of 33 percent activity 

converts into an activity adjustment factor by dividing 0.33 by 5 for the number of days 

the activity occurs divided by 52 which equals 0.00127. 

In addition to the seasonal and activity adjustment factors, further adjustments to 

account for temperature and gasoline volatility have been applied to the following area 

source categories: Service Station Loading (Stage I), Vehicle Refueling (Stage II), 

Gasoline Tank Truck Leaks and Underground Storage Tank Breathing. The 

temperature adjustment factor was calculated using USEPA temperature guidance and 

temperature sensitivity factors from Seasonal Variations in Organic Emissions for 

Significant Sources of Volatile Organic Compounds5. The volatility adjustment factor 

has been calculated based on gasoline Reid pressure (RVP) levels as obtained from 

the Illinois Department of Agriculture Motor Fuel Sampling Results. 

4.2.5 Estimating Emissions at the Township Level 

In addition to the counties of Cook, DuPage, Kane, Lake, McHenry and Will, the 

Chicago NAA also includes Aux Sable and Goose Lake Townships in Grundy County 

and also Oswego Township in Kendall County. Township-specific area source activity 

data is not always available. County emissions are apportioned to the township level 

using other surrogates related to the activity being estimated. These surrogates and 

their resulting percentages, are included in Appendix F. 

37 
4.3 Categorical Emission Summary 

The following sections describe the calculation methodology, source of activity data, 

emission factor(s) used, the resulting emissions and any assumptions (if any) used to 

calculate emissions for the area source category. 

4.3.1 Agricultural Pesticide Application 

Pesticides are defined as any substance used to kill or retard the growth of insects, 

fungi, weeds or microorganisms. Due to lack of pesticide use data by state and local 

units of government and pest control and lawn care companies, emissions estimated 

herein represent only agricultural pesticide use. 

Data concerning the acreage planted in 2002 was obtained from the Illinois Agricultural 

Statistics Service6

. The most recent agricultural pesticide usage data were obtained for 

2002 from the Illinois Agricultural Statistics Service6

. VOM emissions for crops other 

than corn and soybeans were not considered because sufficient data were not available 

to analyze the counties of concern for other crops. In addition, the percentage of 

acreage planted and the total pesticide usage was minor in respect to the total for corn 

and soybeans. Table 4-1 shows the total agricultural pesticide active ingredients per 

acre factors in pounds per year, which were calculated by dividing the State total of 

active ingredient in pesticide applied in 2002 by the State crop acreage in 2002. 

Table 4-1: Agricultural Pesticide Active Ingredient per Acre Factors 

Type Lb VOM/acre/year 

Corn herbicide 2.1582 

Corn insecticide 0.0817 

Soybean herbicide 1.0971 

In developing the emission estimates, it was assumed from Reference 3 the total of 

active ingredients in pesticides should be multiplied by 2.45 to reflect the active and 

inert ingredients. This total quantity should then be multiplied by a factor of 0.9 to 

estimate the amount that evaporates and can be consequently considered as 

photochemically reactive VOM. 

Also according to Reference 3, a seasonal adjustment factor of 1.3 and an activity 

adjustment factor of 0.0032, reflecting activity occurring six days per week, should be 

applied to annual emissions to represent summer weekday emission estimates. Table 

4-2 contains emissions of VOM. Emissions for the nonattainment townships were 

calculated using the percentage of the area for the applicable townships. 

38 
 E = Acres * EF / 2000 (4.1) 

 Where E = emissions (tons/year) 

 Acres = number of acres for a specific crop 

 EF = emission factor (lb VOM/acre/year) 

Table 4-2: Agricultural Pesticide Application Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.12 28.17 

DuPage 0.09 22.12 

Grundy Twps 0.20 48.81 

Kane 1.26 301.93 

Kendall Twps 0.14 34.02 

Lake 4.19 1,003.77 

McHenry 2.61 624.53 

Will 1.82 436.65 

Chicago NAA 10.43 2,500.00 

Jersey 0.93 222.00 

Madison 1.71 408.78 

Monroe 0.91 219.08 

St. Clair 1.29 309.74 

Metro-East NAA 4.84 1,159.60 

Attainment Area 153.40 36,759.49 

State Total 168.67 40,419.09 

4.3.2 Aircraft Refueling 

Emissions from aircraft refueling occur when vapor-laden air in a partially empty fuel 

tank is displaced to the atmosphere as the tank is refilled. The quantity of the vapor 

displaced depends on the fuel temperature, fuel vapor pressure, aircraft fuel tank 

temperature and fuel dispensing rate. The three most common types of aircraft fuels 

used in the United States are jet kerosene (commercial turbojet and turboprop engines), 

aviation gasoline (reciprocating engines) and jet naphtha (military). 

Due to the relatively small amount of emissions generated by this category, Illinois EPA 

applied a growth factor to the emissions calculated in the 1999 periodic inventory. The 

growth factor was obtained from the USEPA’s EGAS model. These growth factors were 

1.163 for the Chicago area, 1.1223 for the Metro-East area and 1.1365 for the other 

areas of the state. 

 E = E1999 * GF (4.2) 

 Where E = emissions (tons/year) 

 E1999 = 1999 emissions (tons/year) 

 GF = growth factor 

39 
The significant emissions for this category occur at only large, commercial airports 

throughout the state. Therefore it is assumed that activity is uniform throughout the 

year which yields a seasonal adjustment factor of 1.0. Aircraft refueling is also 

assumed to take place seven days a week for an activity adjustment factor of 0.00275. 

There are no airports in the nonattainment townships. 

Table 4-3: Aircraft Refueling Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.70 254.79 

DuPage 0.01 4.81 

Grundy Twps 0.00 0.00 

Kane 0.00 0.00 

Kendall Twps 0.00 0.00 

Lake 0.00 0.00 

McHenry 0.00 0.00 

Will 0.01 4.81 

Chicago NAA 0.72 264.41 

Jersey 0.00 0.00 

Madison 0.00 0.00 

Monroe 0.00 0.00 

St. Clair 0.11 38.46 

Metro-East NAA 0.11 38.46 

Attainment Area 0.02 9.62 

State Total 0.85 312.49 

4.3.3 Architectural Coatings 

Architectural surface coatings are used primarily by homeowners and painting 

contractors to coat the interior and exterior of houses and buildings. Emissions result 

when the solvent that carries the coating material evaporates and leaves the coating 

material on the applied surface. 

A per capita emission factor of 3.2266 pounds of VOM per person per year was 

developed based on the 2002 national architectural coatings (water and solvent based) 

usage, population and the applicable VOM content of the coatings. The national 

architectural coatings data were obtained from the 2002 National Paint and Coating 

Association Report7

. National and Illinois county population estimates for 2002 were 

obtained from the U.S. Bureau of Census. 

The calculated emission factor was reduced by 20 percent due to the promulgation of 

the national regulations on consumer products (62FR48848 National Volatile Organic 

Compound Emissions Standards for Architectural Coating, Final rule, September 11, 

1998). VOM emissions in tons per year were estimated by multiplying county 

population by the per capita emission factor. 

40 
E = POP * EF * (1-CE) / 2000 (4.3) 

Where E = emissions (tons/year) 

POP = population 

 EF = emission factor (lb VOM/person/year) 

 CE = control efficiency (0.20) 

For the architectural surface coating category, Reference 1 recommends a seasonal 

adjustment factor of 1.3 indicating increased summertime coating usage. An activity 

factor of 0.00275 reflects uniform activity seven days a week. Emissions for the 

nonattainment townships were calculated using the percentage of the population for the 

applicable townships. 

Table 4-4: Architectural Coating Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 24.81 6,940.43 

DuPage 4.27 1,193.31 

Grundy Twps 0.03 8.52 

Kane 2.04 571.81 

Kendall Twps 0.15 41.09 

Lake 3.11 870.99 

McHenry 1.28 358.42 

Will 2.58 722.58 

Chicago NAA 38.28 10,707.15 

Jersey 0.10 28.21 

Madison 1.21 337.38 

Monroe 0.13 37.50 

St. Clair 1.19 332.86 

Metro-East NAA 2.63 735.95 

Attainment Area 17.23 4,819.69 

State Total 58.14 16,262.79 

4.3.4 Asphalt Paving 

Emissions from asphalt paving occur as a result of the evaporation of the petroleum 

distillate solvent or diluent used to liquefy the asphalt cement. 

According to IDOT’s Bureau of Materials and Physical Research8,9, bituminous 

materials let in 2002 were 4,855,683 gallons and the total Illinois paved roadway miles 

were 139,691. According to AP-422, only 70 percent of the solvent evaporates and 

solvent emissions are representative of kerosene at 6.8 pounds per gallon. 

An emission factor of 165.46 pounds of VOM per lane mile was developed based on the 

total 2002 bituminous material usage, solvent content of the material and paved 

roadway miles along with the assumed evaporation rate. 

41 
E = Miles * EF / 2000 (4.4) 

 Where E = emissions (tons/year) 

 Miles = lane miles (miles) 

 EF = emission factor (lb VOM/lane mile/year) 

According to Reference 3, asphalt paving emissions are assumed to occur six days per 

weeks, six months out of the year, resulting in an activity adjustment factor of 0.00321 

and a seasonal adjustment factor of 2.0. Emissions for the nonattainment townships 

were calculated using the percentage of the miles of road for the applicable townships. 

Table 4-5: Asphalt Paving Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 6.05 941.88 

DuPage 1.64 255.31 

Grundy Twps 0.05 8.42 

Kane 1.13 176.27 

Kendall Twps 0.09 14.87 

Lake 1.43 222.50 

McHenry 1.01 156.87 

Will 1.54 240.16 

Chicago NAA 12.95 2,016.27 

Jersey 0.37 57.64 

Madison 1.38 215.46 

Monroe 0.38 59.49 

St. Clair 1.22 190.41 

Metro-East NAA 3.35 523.00 

Attainment Area 57.86 9,017.34 

State Total 74.16 11,556.61 

4.3.5 Automobile Refinishing 

Automobile refinishing is the cleaning and repainting of automobiles and light trucks and 

other vehicles, but does not include vehicle surface coating during original equipment 

manufacture. Automobile refinishing is a source of emissions due to the evaporation of 

solvents contained in the coatings and cleaning agents used. Emissions of VOM are 

released during three primary activities: surface preparation, coating application and 

equipment cleaning. 

A per capita emission factor of 1.90 pounds of VOM per person per year10 was used to 

calculate emissions. Population estimates were obtained from the U. S. Bureau of 

Census and then multiplied by the emission factor and applicable percent reduction 

factors to obtain the yearly county-wide emission estimates. 

A state rule limits the VOM content of automobile refinishing coatings and surface 

preparation products as well as requiring the use of high efficiency coating application 

42 
equipment in the ozone non-attainment areas. The combination of these controls, 

which took effect in March 1996, resulted in a 72 percent reduction in VOM emissions in 

non-attainment area counties (excluding Jersey County). 

In the attainment areas of the state, automobile refinishing coatings were one of four 

categories affected by the USEPA’s 1998 promulgation of national regulations on 

consumer products. The automobile refinishing coating standards would achieve a 33 

percent statewide reduction in VOM emissions. 

E = POP * EF * (1-CE) / 2000 (4.5) 

 Where E = Emissions (tons/year) 

 POP = Population 

 EF = Emission factor (lb VOM/person/year) 

 CE = control efficiency 

0.72 for non-attainment area (excluding Jersey County) 

0.33 for attainment area (including Jersey County) 

According to Reference 3, automobile refinishing takes place five days per week 

uniformly throughout the year. This results in an activity adjustment factor of 0.00385 

and a seasonal adjustment factor of 1.0. Applying these two adjustments results in 

emission estimates in tons per summer weekday. Emissions for the nonattainment 

townships were calculated using the percentage of the population for the applicable 

townships. 

Table 4-6: Automobile Refinishing Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 4.59 1,430.42 

DuPage 0.79 245.94 

Grundy Twps 0.01 3.79 

Kane 0.38 117.85 

Kendall Twps 0.05 14.13 

Lake 0.58 179.51 

McHenry 0.24 73.87 

Will 0.48 148.92 

Chicago NAA 7.13 2,214.42 

Jersey 0.04 13.91 

Madison 0.22 69.53 

Monroe 0.02 7.73 

St. Clair 0.22 68.60 

Metro-East NAA 0.50 159.77 

Attainment Area 7.55 2,369.28 

State Total 15.18 4,743.47 

43 
4.3.6 Commercial Cooking 

The commercial cooking category includes the cooking of food at restaurants which 

have processes such as chain-driven (conveyorized) charbroilers, under-fired 

charbroilers, deep fat fryers griddles and clamshell griddles. These processes typically 

occur at steak and barbeque, ethnic food, fast food, family and seafood restaurants. 

Emissions inventoried include CO and VOM and do not include combustion emissions. 

Combustion emissions are included in the commercial/institutional fuel combustion 

category. 

Illinois EPA used Reference 11 to calculate emissions from commercial cooking. The 

number of restaurants by each type in each county was used to calculate emissions. 

The type of cooking for each restaurant type was calculated using the values in Table 4-

7. 

Table 4-7: Percent of Restaurants with Each Type of Cooking Equipment 

Restaurant 

Type 

Chain-Driven 

Charbroiler 

Underfired 

Charbroiler

Deep-Fat 

Fryers 

Flat 

Griddles 

Clamshell 

Griddles 

Ethnic 3.5 47.5 81.9 62.7 4.0 

Family 10.1 60.9 91.4 82.9 1.4 

Fast Food 18.6 30.8 96.8 51.9 14.7 

Seafood 0.0 52.6 100.0 36.8 10.5 

Steak & BBQ 6.9 55.2 82.8 89.7 0.0 

Once the number of types of cooking equipment was determined for each restaurant 

type, these values were multiplied by the average number of equipment pieces in Table 

4-8. 

Table 4-8: Average Number of Equipment Pieces by Restaurant Type 

Restaurant 

Type 

Chain-Driven 

Charbroiler 

Underfired 

Charbroiler

Deep-Fat 

Fryers 

Flat 

Griddles 

Clamshell 

Griddles 

Ethnic 1.62 1.54 1.63 1.88 1.8 

Family 1.71 1.29 2.34 2.03 

Fast Food 1.07 1.58 3.1 1.43 2.09 

Seafood 1.1 2.47 1.11 1.5 

Steak & BBQ 1.63 2.42 1.35 

The number of equipment pieces was then summed to the county level for each 

equipment type. These values were then multiplied by the average pounds of meat 

cooked in Table 4-9. 

44 
Table 4-9: Average Pounds of Meat Cooked on Each Type of Equipment Per Week 

Type of Meat Chain-Driven 

Charbroiler 

Underfired 

Charbroiler

Deep-Fat 

Fryers 

Flat 

Griddles 

Clamshell 

Griddles 

Steak 236 180 181 166 94 

Hamburger 798 270 274 362 1314 

Poultry, w/ skin 147 144 365 88 113 

Poultry, w/o skin 266 179 208 111 108 

Pork 57.6 148 58.6 112 118 

Seafood 119 143 159 92.1 632 

Other 41.5 274 57.5 

The amount of meat cooked was then multiplied by 52 to obtain the annual amount of 

meat cooked. This value was then multiplied by the emission factors in Table 4-10 to 

obtain emissions. 

Table 4-10: Commercial Cooking Emission Factors (g/kg meat) 

Equipment Type Meat/Food CO VOM 

Chain-driven Charbroiler Hamburger 8.29 2.27 

Underfired Charbroiler Hamburger 

Steak 

Chicken 

Seafood 

13.72 

4.97 

4.84 

n/a 

3.94 

0.86 

1.82 

0.38 

Deep-fat Fryer Potatoes 

Chicken 

Fish 

n/a 

n/a 

n/a 

0.21 

0.12 

0.14 

Flat Griddle Hamburger 

Chicken 

Seafood 

0.38 

0.45 

n/a 

0.07 

0.4 

0.11 

Clamshell Griddle Hamburger n/a 0.01 

It is assumed that activity takes place seven days per week uniformly throughout the 

year. This results in an activity adjustment factor of 0.00275 and a seasonal adjustment 

factor of 1.0. Emissions for the nonattainment townships were calculated using the 

percentage of the population for the applicable townships. 

45 
Table 4-11: Commercial Cooking Emissions 

County CO 

(tpd) 

CO 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 1.54 562.69 0.57 209.53 

DuPage 0.32 117.73 0.12 43.93 

Grundy Twps 0.00 0.79 0.00 0.30 

Kane 0.09 31.19 0.03 11.55 

Kendall Twps 0.01 2.85 0.00 1.06 

Lake 0.21 75.59 0.08 27.96 

McHenry 0.07 26.14 0.03 9.72 

Will 0.09 34.41 0.04 12.94 

Chicago NAA 2.33 851.39 0.86 316.99 

Jersey 0.01 3.11 0.00 1.16 

Madison 0.07 26.82 0.03 10.06 

Monroe 0.01 2.21 0.00 0.82 

St. Clair 0.06 22.96 0.02 8.58 

Metro-East NAA 0.15 55.10 0.06 20.62 

Attainment Area 1.01 369.92 0.38 137.95 

State Total 3.49 1,276.41 1.30 475.56 

4.3.7 Consumer Solvent Use 

Consumer solvent use is a solvent evaporation emission source of VOM. This category 

has been broken down in seven types of products: personal products, household 

products, auto aftermarket products, adhesive products, pesticide products, 

miscellaneous products and coating & related products. 

Emissions from consumer products are estimated using product-specific per capita 

emission factors. These factors, obtained from EIIP12 are identified in Table 4-12. In 

1998, the USEPA adopted a regulation limiting the VOM content of numerous 

categories of consumer products. The estimate of the reductions made by the 

implementation of the regulation is also identified in the table. 

Table 4-12: Consumer Solvent Use Emission Factors (lb/person/year) 

Product Category 

EIIP 

Emission 

Factor 

Percent 

Reduction 

from 1998 

Rules 

Final 

Emission 

Factor 

Personal Care 2.32 12.11 2.04 

Household 0.79 10.94 0.70 

Automotive Aftermarket 1.36 8.97 1.24 

Adhesives and Sealants 0.57 8.30 0.52 

FIFRA Regulated 1.78 5.08 1.69 

Coatings & Related Products 0.95 0.00 0.95 

Miscellaneous 0.07 0.00 0.07 

46 
Per Reference 3, the use of consumer products is assumed to occur uniformly seven 

days a week throughout the year. This equates to an activity adjustment of 0.00275 

and a seasonal adjustment of 1.0. Emissions for the nonattainment townships were 

calculated using the percentage of the population for the applicable townships. 

Table 4-13: Consumer Solvent Use Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 53.32 19,393.70 

DuPage 9.16 3,334.48 

Grundy Twps 0.07 23.81 

Kane 4.39 1,597.81 

Kendall Twps 0.31 114.82 

Lake 6.69 2,433.81 

McHenry 2.76 1,001.54 

Will 5.54 2,019.11 

Chicago NAA 82.24 29,919.08 

Jersey 0.22 78.83 

Madison 2.59 942.76 

Monroe 0.29 104.80 

St. Clair 2.56 930.11 

Metro-East NAA 5.66 2,056.50 

Attainment Area 36.90 13,467.90 

State Total 124.80 45,443.48 

4.3.8 Dry Cleaning 

Emissions from dry cleaning were calculated using an emission factor of 1800 lb 

VOM/employee from EIIP13. Since perchloroethylene has been determined by USEPA 

to be negligibly reactive and therefore excluded as a volatile organic material, area 

source dry cleaning emissions are limited to those from petroleum operations. 

The number of employees in dry cleaning operations for each county were obtained 

from the 2002 Bureau of Labor Statistics14 using NAICS 81232x. The number of 

employees obtained in this manner includes sources using perchloroethylene as the dry 

cleaning solvent. To calculate only VOM emissions, the percentage of petroleum-based 

dry cleaning to the whole category was obtained from the point source inventory. 

According to the point source inventory, one-third of dry cleaning establishments use 

petroleum based solvents. This factor was applied to the employment to obtain 

emissions. Point source emissions with the SCC of 410xxxxx were then subtracted to 

obtain net area source emissions. 

47 
E = EMP * (1/3) * EF / 2000 – PS (4.6) 

 Where E = emissions (tons/year) 

EMP = number of employees for NAICS 81232x 

 EF = emission factor (1800 lb VOM/employee) 

 PS = point source emissions (tons/year) 

According to Reference 3, dry cleaning activity takes place five days per week uniformly 

throughout the year. This results in an activity adjustment factor of 0.00385 and a 

seasonal adjustment factor of 1.0. Applying these two adjustments results in emission 

estimates in tons per summer weekday. Emissions for the nonattainment townships 

were calculated using the percentage of the population for the applicable townships. 

Table 4-14: Dry Cleaning Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 3.23 838.18 

DuPage 0.60 156.28 

Grundy Twps 0.00 0.70 

Kane 0.35 91.73 

Kendall Twps 0.02 4.05 

Lake 0.43 110.39 

McHenry 0.25 64.14 

Will 0.48 123.94 

Chicago NAA 5.36 1,389.41 

Jersey 0.00 0.84 

Madison 0.13 33.09 

Monroe 0.02 5.00 

St. Clair 0.16 42.50 

Metro-East NAA 0.31 81.43 

Attainment Area 1.59 421.14 

State Total 7.26 1,891.98 

4.3.9 Forest Fires 

Forest fires are fires that occur in wooded areas that are intentionally/unintentionally 

caused by humans plus those caused by nature. Forested acreage and the total 

number of acres burned statewide were obtained from the Illinois Department of Natural 

Resources15. Since no county-level data was available, the number of acres burned 

was apportioned to the county level by the count to state ratio of forested acres. A total 

of 507.8 acres was burned in the state. 

Emissions are calculated using the following formula. 

48 
E = ACRES * EF * LF / 2000 (4.7) 

 Where E = emissions (tons/year) 

 ACRES = number of acres burned 

 EF = emission factor from Table 4-15 (lb/ton burned) 

 LF = loading factor (11 tons burned/acre)16

Table 4-15: Forest Fire Emission Factors (lb/ton of material burned)16

Pollutant Emission 

Factor 

CO 289 

NOx 6.2 

VOM 13.6 

Emissions for the nonattainment townships were apportioned by area. Daily emissions 

were calculated using the same criteria from the 2002 milestone inventory17. These 

values are seven days per week and a seasonal adjustment factor of 2.1. 

Table 4-16: Forest Fire Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.04 6.54 0.00 0.14 0.00 0.31 

DuPage 0.02 3.03 0.00 0.07 0.00 0.14 

Grundy Twps 0.00 0.03 0.00 0.00 0.00 0.00 

Kane 0.01 2.13 0.00 0.05 0.00 0.10 

Kendall Twps 0.00 0.07 0.00 0.00 0.00 0.00 

Lake 0.00 0.00 0.00 0.00 0.00 0.00 

McHenry 0.01 2.47 0.00 0.05 0.00 0.12 

Will 0.02 2.80 0.00 0.06 0.00 0.13 

Chicago NAA 0.10 17.07 0.00 0.37 0.00 0.80 

Jersey 0.01 2.40 0.00 0.05 0.00 0.11 

Madison 0.02 4.33 0.00 0.09 0.00 0.20 

Monroe 0.02 2.71 0.00 0.06 0.00 0.13 

St. Clair 0.02 3.55 0.00 0.08 0.00 0.17 

Metro-East NAA 0.07 12.98 0.00 0.28 0.00 0.61 

Attainment Area 1.36 235.18 0.03 5.04 0.06 11.07 

State Total 1.53 265.23 0.03 5.69 0.07 12.48 

4.3.10 Fuel Combustion – Commercial/Institutional 

Commercial/industrial fuel combustion emissions, which result form the combustion of 

natural gas, distillate oil, residual oil, coal, kerosene and LPG, are a source of emissions 

from both point and area sources. Gross area source emissions are estimated using 

the total estimated statewide fuel usage for each fuel type. In order to avoid double 

49 
counting of emissions, county fuel-specific point source emissions are subtracted from 

the gross area source estimate to determine the county net area source emission 

estimate. As development of the point source inventory has changed over time, 

comparison of category emissions for different years could yield significant differences. 

In addition, changes in the Energy Information Administration (EIA) reporting formats 

also result in variations in the estimated emissions. 

Emissions were calculated for the combustion of natural gas, distillate oil, residual oil, 

kerosene and LPG. It is assumed that industrial coal combustion emissions are 

completely accounted for in the point source inventory since all boilers that have a heat 

input rate greater than 10 million BTU/hr are required to have a permit. It is very 

unlikely a coal fired boiler at an industrial source would be less than this threshold. 

Emissions were calculated using emission factors from Reference 10. These factors 

are presented in Table 4-17. 

Table 4-17: Commercial/Institutional Fuel Combustion Emission Factors10

Fuel Pollutant Emission 

Factor 

Units 

Natural Gas CO 

NOx 

VOM 

84 

100 

5.5 

Lb/million cubic feet 

Lb/million cubic feet 

Lb/million cubic feet 

Distillate Oil CO 

NOx 

VOM 

5 

24 

0.34 

Lb/1000 gallons 

Lb/1000 gallons 

Lb/1000 gallons 

Residual Oil CO 

NOx 

VOM 

5 

47 

1.13 

Lb/1000 gallons 

Lb/1000 gallons 

Lb/1000 gallons 

Kerosene CO 

NOx 

VOM 

5 

55 

1.13 

Lb/1000 gallons 

Lb/1000 gallons 

Lb/1000 gallons 

LPG CO 

NOx 

VOM 

1.9 

14 

0.3 

Lb/1000 gallons 

Lb/1000 gallons 

Lb/1000 gallons 

Calculation of daily emissions was performed using the fuel use data from the EIA for 

the period of May through September 2002 in combination with the emission factors 

above. The value was then divided by 153 to obtain daily emissions. For 2002, 39.806 

million cubic feet of gas, 13.55 million gallons of distillate oil, 0.11 million gallons of 

residual oil, 0.3 million gallons of kerosene and 7.7 million gallons of LPG were 

combustion between May and September of 2002. 

Statewide emissions were apportioned to counties based on the 2002 county-to-state 

ratio of employment in NAICS 401-99914. Employment for the nonattainment townships 

50 
was calculated using the percentage of the population for the applicable townships. 

Once this had been completed, the point source emissions were subtracted from the 

statewide number for each fuel, resulting in the net area source component of industrial 

fuel combustion emissions. In situations where the point source emissions exceeded 

the gross area source estimate, the net area source emissions were reported as zero. 

Table 4-18: Commercial/Institutional Natural Gas Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 4,039.08 3.43 4,652.75 0.21 258.92 

DuPage 0.09 876.01 1.07 1,035.68 0.05 56.44 

Grundy Twps 0.00 2.84 0.00 3.21 0.00 0.18 

Kane 0.00 225.22 0.12 240.46 0.01 14.72 

Kendall Twps 0.00 8.53 0.00 9.71 0.00 0.54 

Lake 0.00 447.35 0.61 539.54 0.00 26.89 

McHenry 0.03 121.18 0.16 140.04 0.01 7.70 

Will 0.00 181.39 0.13 201.73 0.01 11.43 

Chicago NAA 0.12 5,901.60 5.52 6,823.13 0.29 376.81 

Jersey 0.00 4.95 0.01 5.90 0.00 0.32 

Madison 0.00 130.75 0.15 153.72 0.01 8.47 

Monroe 0.00 11.05 0.01 13.15 0.00 0.72 

St. Clair 0.00 125.02 0.15 108.76 0.01 7.11 

Metro-East NAA 0.01 271.77 0.17 281.53 0.02 16.62 

Attainment Area 0.16 1,690.22 1.67 1,848.35 0.09 106.65 

State Total 0.29 7,863.60 7.36 8,953.00 0.39 500.08 

Table 4-19: Commercial/Institutional Distillate Oil Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 0.00 0.00 0.00 0.00 0.00 

DuPage 0.00 0.14 0.00 1.39 0.00 0.03 

Grundy Twps 0.00 0.00 0.00 0.01 0.00 0.00 

Kane 0.00 0.04 0.00 0.40 0.00 0.01 

Kendall Twps 0.00 0.00 0.00 0.02 0.00 0.00 

Lake 0.00 0.07 0.00 0.71 0.00 0.01 

McHenry 0.00 0.02 0.00 0.19 0.00 0.01 

Will 0.00 0.03 0.00 0.30 0.00 0.01 

Chicago NAA 0.27 125.53 1.20 606.51 0.02 8.51 

Jersey 0.00 0.00 0.00 0.01 0.00 0.00 

Madison 0.00 0.02 0.00 0.21 0.00 0.01 

Monroe 0.00 0.00 0.00 0.01 0.00 0.00 

St. Clair 0.00 0.02 0.00 0.22 0.00 0.01 

Metro-East NAA 0.02 5.88 0.02 28.46 0.00 0.41 

Attainment Area 0.10 40.23 0.37 195.38 0.01 2.72 

State Total 0.38 171.64 1.59 830.35 0.02 11.64 

51 
Table 4-20: Commercial/Institutional Residual Oil Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 0.00 0.00 0.00 0.00 0.00 

DuPage 0.00 0.14 0.00 1.39 0.00 0.03 

Grundy Twps 0.00 0.00 0.00 0.01 0.00 0.00 

Kane 0.00 0.04 0.00 0.40 0.00 0.01 

Kendall Twps 0.00 0.00 0.00 0.02 0.00 0.00 

Lake 0.00 0.07 0.00 0.71 0.00 0.01 

McHenry 0.00 0.02 0.00 0.19 0.00 0.01 

Will 0.00 0.03 0.00 0.30 0.00 0.01 

Chicago NAA 0.00 0.30 0.01 3.01 0.00 0.06 

Jersey 0.00 0.00 0.00 0.01 0.00 0.00 

Madison 0.00 0.02 0.00 0.21 0.00 0.01 

Monroe 0.00 0.00 0.00 0.01 0.00 0.00 

St. Clair 0.00 0.02 0.00 0.22 0.00 0.01 

Metro-East NAA 0.00 0.04 0.00 0.45 0.00 0.01 

Attainment Area 0.00 0.30 0.01 2.88 0.00 0.07 

State Total 0.00 0.64 0.02 6.33 0.00 0.14 

Table 4-21: Commercial/Institutional Kerosene Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 1.95 0.00 21.53 0.00 0.44 

DuPage 0.00 0.39 0.00 4.37 0.00 0.09 

Grundy Twps 0.00 0.00 0.00 0.02 0.00 0.00 

Kane 0.00 0.11 0.00 1.26 0.00 0.02 

Kendall Twps 0.00 0.01 0.00 0.05 0.00 0.00 

Lake 0.00 0.20 0.00 2.25 0.00 0.04 

McHenry 0.00 0.05 0.00 0.60 0.00 0.01 

Will 0.00 0.08 0.00 0.96 0.00 0.02 

Chicago NAA 0.00 2.79 0.00 31.03 0.00 0.62 

Jersey 0.00 0.00 0.00 0.02 0.00 0.00 

Madison 0.00 0.06 0.00 0.67 0.00 0.01 

Monroe 0.00 0.01 0.00 0.05 0.00 0.00 

St. Clair 0.00 0.06 0.00 0.71 0.00 0.01 

Metro-East NAA 0.00 0.13 0.00 1.45 0.00 0.02 

Attainment Area 0.00 0.88 0.00 10.05 0.00 0.19 

State Total 0.00 3.79 0.00 42.53 0.00 0.83 

52 
Table 4-22: Commercial/Institutional LPG Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.05 19.49 0.39 143.63 0.01 3.08 

DuPage 0.01 3.96 0.08 29.19 0.00 0.63 

Grundy Twps 0.00 0.02 0.00 0.12 0.00 0.00 

Kane 0.00 1.15 0.02 8.44 0.00 0.18 

Kendall Twps 0.00 0.05 0.00 0.34 0.00 0.01 

Lake 0.01 2.04 0.04 15.03 0.00 0.32 

McHenry 0.00 0.54 0.01 4.01 0.00 0.09 

Will 0.00 0.87 0.02 6.45 0.00 0.14 

Chicago NAA 0.08 28.11 0.57 207.21 0.01 4.45 

Jersey 0.00 0.02 0.00 0.16 0.00 0.00 

Madison 0.00 0.61 0.01 4.49 0.01 0.10 

Monroe 0.00 0.05 0.00 0.36 0.00 0.01 

St. Clair 0.00 0.64 0.01 4.74 0.00 0.10 

Metro-East NAA 0.00 1.32 0.03 9.75 0.00 0.21 

Attainment Area 0.02 9.01 0.18 67.00 0.00 1.36 

State Total 0.11 38.44 0.78 283.96 0.02 6.02 

4.3.11 Fuel Combustion – Industrial 

Industrial fuel combustion emissions, which result form the combustion of natural gas, 

distillate oil, residual oil and coal, are a source of emissions from both point and area 

sources. Gross area source emissions are estimated using the total estimated 

statewide fuel usage for each fuel type. In order to avoid double counting of emissions, 

county fuel-specific point source emissions are subtracted from the gross area source 

estimate to determine the county net area source emission estimate. As development 

of the point source inventory has changed over time, comparison of category emissions 

for different years could yield significant differences. In addition, changes in the Energy 

Information Administration (EIA) reporting formats also result in variations in the 

estimated emissions. 

Emissions were calculated for the combustion of natural gas, distillate oil and residual 

oil. It is assumed that industrial coal combustion emissions are completely accounted 

for in the point source inventory since all boilers that have a heat input rate greater than 

10 million BTU/hr are required to have a permit. It is very unlikely a coal fired boiler at 

an industrial source would be less than this threshold. It is further assumed that 

industrial combustion does not make use of kerosene and LPG as fuels in external 

combustion sources. 

Emissions were calculated using emission factors from Reference 10. These factors 

are presented in Table 4-23. 

53 
Table 4-23: Industrial Fuel Combustion Emission Factors10

Fuel Pollutant Emission 

Factor 

Units 

Natural Gas CO 

NOx 

VOM 

84 

100 

5.5 

Lb/million cubic feet 

Lb/million cubic feet 

Lb/million cubic feet 

Distillate Oil CO 

NOx 

VOM 

5 

20 

0.2 

Lb/1000 gallons 

Lb/1000 gallons 

Lb/1000 gallons 

Residual Oil CO 

NOx 

VOM 

5 

55 

0.28 

Lb/1000 gallons 

Lb/1000 gallons 

Lb/1000 gallons 

Calculation of daily emissions was performed using the fuel use data from the EIA for 

the period of May through September 2002 in combination with the emission factors 

above. The value was then divided by 153 to obtain daily emissions. For 2002, 

100,000 million cubic feet of gas, 62.283 million gallons of distillate oil and 3.826 million 

gallons of residual oil were combusted between May and September of 2002. 

Statewide emissions were apportioned to counties based on the 2002 county-to-state 

ratio of employment in NAICS 311-39914. Employment for the nonattainment townships 

was calculated using the percentage of the population for the applicable townships. 

Once this had been completed, the point source emissions were subtracted from the 

statewide number for each fuel, resulting in the net area source component of industrial 

fuel combustion emissions. In cases where the point source emissions exceeded the 

gross area source estimate, the net area source emissions were reported as zero. 

Table 4-24: Industrial Natural Gas Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 3,942.67 9.28 4,531.80 0.00 217.46 

DuPage 0.31 975.37 3.15 1,154.93 0.00 63.46 

Grundy Twps 0.00 0.00 0.00 0.42 0.00 0.03 

Kane 0.03 506.46 1.30 563.72 0.00 30.11 

Kendall Twps 0.02 30.27 0.10 37.10 0.00 2.05 

Lake 0.37 782.30 2.61 920.55 0.00 51.68 

McHenry 0.20 282.22 1.08 341.33 0.01 18.26 

Will 0.00 88.06 0.00 138.70 0.00 6.90 

Chicago NAA 0.93 6,607.35 17.52 7,688.54 0.01 389.95 

Jersey 0.00 1.66 0.01 1.98 0.00 0.10 

Madison 0.00 251.68 0.00 287.08 0.00 13.99 

Monroe 0.01 4.74 0.01 5.55 0.00 0.30 

St. Clair 0.00 79.99 0.00 82.67 0.00 3.27 

Metro-East NAA 0.01 338.07 0.02 377.28 0.00 17.66 

Attainment Area 0.53 2,314.57 5.97 2,478.96 0.04 136.84 

State Total 1.47 9,259.99 23.51 10,544.78 0.06 544.45 

54 
Table 4-25: Industrial Distillate Oil Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 56.85 0.00 228.13 0.00 2.30 

DuPage 0.03 13.45 0.14 53.83 0.00 0.53 

Grundy Twps 0.00 0.05 0.00 0.21 0.00 0.00 

Kane 0.02 7.53 0.08 30.07 0.00 0.30 

Kendall Twps 0.00 0.37 0.01 1.48 0.00 0.01 

Lake 0.02 9.59 0.11 41.68 0.00 0.38 

McHenry 0.01 3.92 0.04 15.69 0.00 0.15 

Will 0.00 3.54 0.00 14.18 0.00 0.14 

Chicago NAA 0.08 95.30 0.38 385.27 0.00 3.81 

Jersey 0.00 0.02 0.00 0.08 0.00 0.00 

Madison 0.00 0.00 0.00 0.00 0.00 0.00 

Monroe 0.00 0.06 0.00 0.25 0.00 0.00 

St. Clair 0.00 0.93 0.01 3.73 0.00 0.03 

Metro-East NAA 0.00 1.01 0.01 4.06 0.00 0.03 

Attainment Area 0.09 39.82 0.38 167.34 0.00 1.48 

State Total 0.17 136.13 0.76 556.67 0.00 5.32 

Table 4-26: Industrial Residual Oil Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 0.03 0.00 0.37 0.00 0.00 

DuPage 0.00 0.04 0.00 0.48 0.00 0.00 

Grundy Twps 0.00 0.00 0.00 0.01 0.00 0.00 

Kane 0.00 0.00 0.00 0.01 0.00 0.00 

Kendall Twps 0.00 0.00 0.00 0.00 0.00 0.00 

Lake 0.00 0.05 0.00 0.55 0.00 0.00 

McHenry 0.00 0.01 0.00 0.20 0.00 0.00 

Will 0.00 0.06 0.00 0.71 0.00 0.00 

Chicago NAA 0.00 0.19 0.01 2.32 0.00 0.01 

Jersey 0.00 0.03 0.00 0.38 0.00 0.00 

Madison 0.00 0.01 0.00 0.13 0.00 0.00 

Monroe 0.00 0.00 0.00 0.04 0.00 0.00 

St. Clair 0.00 0.13 0.00 1.50 0.00 0.01 

Metro-East NAA 0.00 0.17 0.00 2.05 0.00 0.01 

Attainment Area 0.01 5.62 0.15 63.59 0.00 0.30 

State Total 0.01 5.99 0.16 68.00 0.00 0.32 

4.3.12 Fuel Combustion – Residential 

Residential dwellings are defined as all structures containing fewer than 20 living units. 

Emissions are estimated for residential activities that utilize fuel for water heating, space 

heating and cooking. Fuels used for residential activities are natural gas, fuel oil, 

kerosene, LPG, coal and wood. The combustion of coal, kerosene and wood at 

residences during the summer months is assumed to be zero since these types of fuels 

are primarily used for space heating. 

55 
4.3.12.1 Fuels other than Wood 

Emissions were calculated using emission factors from Reference 16. These factors 

are presented in Table 4-27. 

Table 4-27: Residential Fuel Combustion Emission Factors other than Wood16

Fuel Pollutant Emission 

Factor 

Units 

Natural Gas CO 

NOx 

VOM 

40 

94 

5.5 

Lb/million cubic feet 

Lb/million cubic feet 

Lb/million cubic feet 

Distillate Oil CO 

NOx 

VOM 

5 

18 

0.7 

Lb/1000 gallons 

Lb/1000 gallons 

Lb/1000 gallons 

Kerosene CO 

NOx 

VOM 

4.8 

17.4 

0.7 

Lb/1000 gallons 

Lb/1000 gallons 

Lb/1000 gallons 

LPG CO 

NOx 

VOM 

3.2 

13 

0.5 

Lb/1000 gallons 

Lb/1000 gallons 

Lb/1000 gallons 

Coal CO 

NOx 

VOM 

275 

9.1 

10 

Lb/ton 

Lb/ton 

Lb/ton 

Fuel use data was obtained from the EIA for each month in 2002. Daily emissions were 

calculated using the months May through September and dividing by 153 to obtain a 

daily fuel use rate. 

Table 4-28: Statewide Residential Fuel Combustion Fuel Use18

Fuel Annual MaySeptember Units 

Natural Gas 465,543 64,450 Million cubic feet 

Distillate Oil 11.4 1.6 Million gallons 

Kerosene 6.0 0 Million gallons 

LPG 228.23 31.6 Million gallons 

Coal 25,000 0 Tons 

Wood 437.3 0 1000 cords 

Statewide fuel use was apportioned to counties based on data from the 2000 Census 

that provided the number of homes in each county that has that particular fuel used for 

primary heating. No data was available for kerosene so its distribution was assumed to 

be identical to distillate oil. 

56 
Table 4-29: Residential Natural Gas Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 1.92 4,256.26 9.62 10,002.21 0.51 585.24 

DuPage 0.32 721.68 1.63 1,695.95 0.08 99.23 

Grundy Twps 0.00 4.61 0.01 10.84 0.00 0.63 

Kane 0.13 303.63 0.68 713.53 0.03 41.75 

Kendall Twps 0.01 20.69 0.05 48.62 0.00 2.84 

Lake 0.21 481.40 1.08 1,131.3 0.05 66.19 

McHenry 0.08 197.05 0.44 463.08 0.02 27.09 

Will 0.17 381.10 0.86 895.59 0.04 52.40 

Chicago NAA 2.84 6,366.42 14.37 14,961.12 0.73 875.38 

Jersey 0.00 8.37 0.01 19.68 0.00 1.15 

Madison 0.08 185.89 0.42 436.84 0.02 25.56 

Monroe 0.01 11.65 0.02 27.38 0.00 1.60 

St. Clair 0.07 174.05 0.39 409.02 0.02 23.93 

Metro-East NAA 0.16 379.96 0.84 892.92 0.04 52.24 

Attainment Area 1.05 2,564.48 5.46 6,026.45 0.26 352.56 

State Total 4.04 9,310.86 20.67 21,880.49 1.03 1,280.18 

Table 4-30: Residential Distillate Oil Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.02 9.50 0.09 34.22 0.00 1.33 

DuPage 0.00 0.36 0.00 1.29 0.00 0.05 

Grundy Twps 0.00 0.01 0.00 0.04 0.00 0.00 

Kane 0.00 0.42 0.00 1.53 0.00 0.06 

Kendall Twps 0.00 0.10 0.00 0.35 0.00 0.02 

Lake 0.00 0.49 0.01 1.76 0.00 0.07 

McHenry 0.00 0.27 0.00 0.96 0.00 0.04 

Will 0.00 0.32 0.00 1.17 0.00 0.05 

Chicago NAA 0.03 11.47 0.11 41.33 0.00 1.62 

Jersey 0.00 0.15 0.00 0.53 0.00 0.02 

Madison 0.00 1.46 0.01 5.25 0.00 0.20 

Monroe 0.00 0.11 0.00 0.40 0.00 0.02 

St. Clair 0.00 0.81 0.01 0.81 0.00 0.11 

Metro-East NAA 0.01 2.53 0.02 9.09 0.00 0.35 

Attainment Area 0.03 14.49 0.14 52.21 0.00 2.03 

State Total 0.06 28.49 0.27 102.63 0.01 4.00 

57 
Table 4-31: Residential Kerosene Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 4.79 0.00 17.35 0.00 0.70 

DuPage 0.00 0.18 0.00 0.65 0.00 0.03 

Grundy Twps 0.00 0.01 0.00 0.02 0.00 0.00 

Kane 0.00 0.21 0.00 0.77 0.00 0.03 

Kendall Twps 0.00 0.05 0.00 0.18 0.00 0.01 

Lake 0.00 0.25 0.00 0.89 0.00 0.04 

McHenry 0.00 0.13 0.00 0.49 0.00 0.02 

Will 0.00 0.16 0.00 0.59 0.00 0.02 

Chicago NAA 0.00 5.77 0.00 20.94 0.00 0.85 

Jersey 0.00 0.07 0.00 0.27 0.00 0.01 

Madison 0.00 0.73 0.00 2.66 0.00 0.11 

Monroe 0.00 0.06 0.00 0.20 0.00 0.01 

St. Clair 0.00 0.41 0.00 1.47 0.00 0.06 

Metro-East NAA 0.00 1.27 0.00 4.60 0.00 0.19 

Attainment Area 0.00 7.29 0.00 26.47 0.00 1.08 

State Total 0.00 14.33 0.00 52.01 0.00 2.12 

Table 4-32: Residential LPG Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.04 47.91 0.18 194.65 0.01 7.49 

DuPage 0.00 2.66 0.01 10.79 0.00 0.41 

Grundy Twps 0.00 0.35 0.00 1.41 0.00 0.05 

Kane 0.00 3.41 0.01 13.87 0.00 0.53 

Kendall Twps 0.00 1.04 0.00 4.21 0.00 0.16 

Lake 0.00 2.59 0.01 10.52 0.00 0.40 

McHenry 0.00 4.34 0.02 17.64 0.00 0.68 

Will 0.01 6.12 0.02 24.87 0.00 0.96 

Chicago NAA 0.06 68.41 0.25 277.97 0.01 10.69 

Jersey 0.00 4.70 0.02 19.10 0.00 0.73 

Madison 0.01 9.61 0.04 39.05 0.00 1.50 

Monroe 0.00 4.68 0.02 19.01 0.00 0.73 

St. Clair 0.01 8.71 0.03 35.38 0.00 1.36 

Metro-East NAA 0.02 27.70 0.10 112.54 0.00 4.32 

Attainment Area 0.25 274.41 1.00 1,114.81 0.04 42.90 

State Total 0.33 370.52 1.35 1,505.31 0.05 57.90 

58 
Table 4-33: Residential Coal Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 2,249.12 0.00 74.43 0.00 81.79 

DuPage 0.00 70.75 0.00 2.34 0.00 2.57 

Grundy Twps 0.00 0.00 0.00 0.00 0.00 0.00 

Kane 0.00 37.24 0.00 1.23 0.00 1.35 

Kendall Twps 0.00 0.00 0.00 0.00 0.00 0.00 

Lake 0.00 0.00 0.00 0.00 0.00 0.00 

McHenry 0.00 7.45 0.00 0.25 0.00 0.27 

Will 0.00 37.24 0.00 1.23 0.00 1.35 

Chicago NAA 0.00 2,401.80 0.00 79.48 0.00 87.33 

Jersey 0.00 0.00 0.00 0.00 0.00 0.00 

Madison 0.00 7.45 0.00 0.25 0.00 0.27 

Monroe 0.00 11.17 0.00 0.37 0.00 0.41 

St. Clair 0.00 0.00 0.00 0.00 0.00 0.00 

Metro-East NAA 0.00 18.62 0.00 0.62 0.00 0.68 

Attainment Area 0.00 1,072.45 0.00 35.54 0.00 39.01 

State Total 0.00 3,492.87 0.00 115.64 0.00 127.02 

4.3.12.2 Wood Combustion in Stoves and Fireplaces 

Residential wood combustion is defined as wood burning that takes place primarily in 

wood stoves and fireplaces. Residential wood burning occurs either as a necessary 

source of heat or for aesthetics. For the purposes of this inventory wood burning 

equipment is broken down into the following categories. 

• Fireplaces without inserts 

• Fireplaces with inserts 

o Catalytic, not EPA certified 

o Catalytic, EPA certified 

o Non-catalytic, EPA certified 

• Wood stoves 

o Conventional 

o Catalytic 

o Non-catalytic 

No survey was performed to determine the type and amount of devices burning wood at 

residences. Rather, the American Housing Survey19-21 was used to establish the 

number of devices. No single report included the entire state of Illinois so it was 

necessary to use reports from different years. Table 4-34 describes which reports were 

used for each county. The 2001 report was not specific to any counties but was for the 

Midwest Region. 

59 
Table 4-34: Application of American Housing Survey 

Counties Year of American 

Housing Survey 

Cook, DuPage, Grundy, 

Kendall, Lake, McHenry 

and Will 

Chicago 1999 

Clinton, Jersey, Madison, 

Monroe, St. Clair 

St. Louis 1996 

All other counties National 2001 

The number of wood stoves for each county using wood as the primary heat source was 

calculated using the ratio of wood stoves to total devices from the applicable American 

Housing Survey times the number of residences using wood as a primary heat source. 

This same calculation was performed for fireplaces using wood as the primary heat 

source. To calculate the number of wood stoves using wood as a secondary heat 

source, the ratio of secondary to primary heating fuel for wood stoves was used from 

the applicable American Housing Survey and multiplied by the previously calculated 

amount of wood stoves using wood as a primary fuel. The same calculation was 

performed for fireplaces. 

The number of wood stoves and fireplaces was summed to obtain the total number of 

devices burning wood in the state. This value was used to apportion the amount of 

wood burned in the state, 538,000 cords18 or 0.626 tons to the county level. It was 

noticed that the number of devices burning wood that was calculated using the 

methodology above yielded an absurdly high number of devices per residence. This 

value was typically in the range of 10-15 stoves/fireplaces per residence. Using this 

value does not cause a problem with the inventory since the percentage, and not the 

individual numbers, are being used to apportion fuel use. 

From Reference 18, the amount of wood burned in fireplaces was 65.6 percent of the 

total amount of wood burned. The amount of wood burned was then used in the 

following equation to calculate emissions. 

E = WOOD * EF / 2000 (4.8) 

 Where E = emissions (tons/year) 

 WOOD = amount of wood burned in the particular device (tons/year) 

 EF = appropriate emission factor from Table 4-35 

60 
Table 4-35: Residential Wood Combustion Emission Factors16 (lb/ton burned) 

Type of Device and Pollutant Emission 

Factor 

Fireplace w/o insert 

 CO 

 NOx 

 VOM 

64.1 

2.6 

229.0 

Fireplace with insert (catalytic, not EPA certified) 

 CO 

 NOx 

 VOM 

231.0 

2.8 

53.1 

Fireplace with insert (non-catalytic, EPA certified) 

 CO 

 NOx 

 VOM 

141.0 

0.0 

12.0 

Fireplace with insert (catalytic, EPA certified) 

 CO 

 NOx 

 VOM 

104 

2.0 

15.0 

Wood Stove (conventional) 

 CO 

 NOx 

 VOM 

231.0 

2.8 

53.0 

Wood Stove (catalytic) 

 CO 

 NOx 

 VOM 

104.0 

2.0 

15.0 

Wood Stove (non-catalytic) 

 CO 

 NOx 

 VOM 

141.0 

0.0 

12.0 

For the nonattainment townships, emissions were apportioned to the township level 

using population. It is assumed that residential wood combustion does not take place 

during the ozone season. 

61 
Table 4-36: Residential Wood Combustion Fireplace Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 1,250.57 0.00 27.34 0.00 1,748.88 

DuPage 0.00 201.92 0.00 4.41 0.00 282.46 

Grundy Twps 0.00 43.66 0.00 0.96 0.00 61.07 

Kane 0.00 316.67 0.00 6.93 0.00 442.82 

Kendall Twps 0.00 45.43 0.00 0.99 0.00 63.48 

Lake 0.00 543.87 0.00 11.89 0.00 760.69 

McHenry 0.00 773.46 0.00 16.90 0.00 1,081.62 

Will 0.00 818.14 0.00 18.25 0.00 1,116.98 

Chicago NAA 0.00 3,993.71 0.00 87.67 0.00 5,558.05 

Jersey 0.00 318.74 0.00 7.93 0.00 557.82 

Madison 0.00 1,115.14 0.00 27.87 0.00 1,965.90 

Monroe 0.00 356.54 0.00 5.66 0.00 992.44 

St. Clair 0.00 371.91 0.00 4.85 0.00 1,149.76 

Metro-East NAA 0.00 2,162.33 0.00 46.31 0.00 4,665.92 

Attainment Area 0.00 23,753.74 0.00 401.94 0.00 17,880.39 

State Total 0.00 29,909.78 0.00 535.92 0.00 28,104.36 

Table 4-37: Residential Wood Combustion Wood Stove Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 1,218.94 0.00 14.79 0.00 274.32 

DuPage 0.00 196.84 0.00 2.39 0.00 44.31 

Grundy Twps 0.00 42.56 0.00 0.52 0.00 9.58 

Kane 0.00 308.67 0.00 3.75 0.00 69.46 

Kendall Twps 0.00 44.26 0.00 0.54 0.00 9.96 

Lake 0.00 530.17 0.00 6.43 0.00 119.31 

McHenry 0.00 753.89 0.00 9.15 0.00 169.66 

Will 0.00 778.54 0.00 9.45 0.00 175.21 

Chicago NAA 0.00 3,873.87 0.00 47.01 0.00 871.81 

Jersey 0.00 353.93 0.00 4.29 0.00 79.64 

Madison 0.00 1,243.77 0.00 15.09 0.00 279.91 

Monroe 0.00 627.60 0.00 7.62 0.00 141.42 

St. Clair 0.00 728.55 0.00 8.84 0.00 163.96 

Metro-East NAA 0.00 2,954.65 0.00 35.84 0.00 664.93 

Attainment Area 0.00 17,029.71 0.00 242.43 0.00 3,832.52 

State Total 0.00 23,858.23 0.00 289.44 0.00 5,369.26 

4.3.13 Gasoline Marketing 

Gasoline is produced by petroleum refineries and then is transported through a 

distribution network to customers. The distribution network is a complex system that 

includes many wholesale and retail outlets. The network includes a variety of storage 

and transfer facilities. Gasoline may be transported by tanker ships and barges, 

through pipelines or by rail tank cars or trucks. The four main sources of emissions in 

the distribution network are: 

62 
• Service station loading (Stage I) 

• Vehicle refueling (Stage II) 

• Tank truck leaks 

• Storage tank breathing 

4.3.13.1 Service Station Loading (Stage I) 

Emissions from service station loading occur as a vapor is forced out of a storage tank 

during the transfer of fuel from a tank truck. This process is commonly referred to as 

Stage I. The quantity of emissions is based on the throughput of gasoline and is 

affected by the fuel temperature, fuel volatility and whether vapor recovery is required. 

Vapor recovery is required in the entire Chicago and Metro East nonattainment areas. 

Vapor recovery is also required in certain attainment counties which include Boone, 

Peoria, Rock Island Tazewell and Winnebago Counties. For areas required to have 

vapor recovery, a 95 percent control efficiency is assumed with a rule effectiveness of 

95 percent. 

Table 4-38: Stage I Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 2.26 639.32 

DuPage 0.56 159.37 

Grundy Twps 0.07 20.34 

Kane 0.22 63.44 

Kendall Twps 0.09 25.35 

Lake 0.38 108.67 

McHenry 0.14 38.35 

Will 0.29 82.50 

Chicago NAA 4.01 1,137.34 

Jersey 0.10 29.24 

Madison 0.20 55.48 

Monroe 0.02 6.75 

St. Clair 0.19 52.94 

Metro-East NAA 0.51 144.41 

Attainment Area 17.89 5,060.16 

State Total 22.41 6,341.91 

4.3.13.2 Vehicle Refueling (Stage II) 

Emissions from vehicle refueling, commonly known as Stage II, occur as vapors are 

displaced from automobile tanks during filling and from spillage of gasoline. The 

quantity of displaced vapors is based on gasoline throughput and is affected by liquid 

temperature, volatility and the affect of vapor recovery equipment. Stage II vapor 

recovery equipment is required at all service stations in the Chicago NAA that market in 

63 
excess of 10,000 gallons per month. The combination of this applicability level and the 

annual inspection cycle results in an overall program efficiency of 84 percent. Using 

these inputs and assuming the use of reformulated gasoline, the MOBILE6 model 

generated a vehicle refueling emission factor of 0.029 g/VMT. 

Stage II vapor recovery is not required in the Metro-East NAA. In determining the Stage 

II emission factor with the MOBILE6 model, a 30 percent ethanol blend market share 

was included. This resulted in a vehicle refueling emission factor of 0.136 g/VMT. 

Stage II vapor recovery is also not required in the attainment areas of the state. The 

MOBILE6 model was used to calculate emission factors using a 30 percent market 

share of ethanol blend. This calculation was performed once for the counties in the 

northern part of the state, resulting in an emission factor of 0.145 g/VMT, and once for 

the counties in the southern part of the state, resulting in an emission factor of 0.157 

g/VMT. 

Statewide and countywide ADVMT information was obtained from IDOT’s 2002 Illinois 

Travel Statistics22. Emissions are calculated using the following formula: 

E = VMT * EF / 453.59 / 2000 (4.9) 

 Where E = emissions (tons/year) 

 VMT = vehicle miles traveled 

 EF = emission factor from Table 4-38 (g/VMT) 

Table 4-39: Stage II Emission Factors (grams VOM/VMT) 

Area of the State Emission 

Factor 

Chicago NAA 0.029 

Metro-East NAA 0.136 

Northern 0.145 

Southern 0.157 

Daily emissions are calculated using an activity adjustment factor of 0.0032 and a 

seasonal adjustment factor of 1.1. Emissions in the nonattainment townships are based 

on the percentage of VMT of the township to the whole county. 

64 
Table 4-40: Stage II Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 3.26 1,092.22 

DuPage 0.81 272.27 

Grundy Twps 0.06 4.53 

Kane 0.32 108.38 

Kendall Twps 0.06 5.64 

Lake 0.55 185.66 

McHenry 0.20 65.52 

Will 0.42 140.95 

Chicago NAA 5.68 1,875.16 

Jersey 0.11 35.64 

Madison 1.24 415.82 

Monroe 0.15 50.60 

St. Clair 1.18 396.82 

Metro-East NAA 2.68 898.88 

Attainment Area 20.30 6,743.00 

State Total 28.65 9,517.04 

4.3.13.3 Gasoline Tank Truck Leaks 

Evaporation of gasoline vapor from loaded tank trucks during transportation of gasoline 

from the bulk plant/terminal to the service station and evaporation from empty tank 

trucks returning from service stations to bulk plants/terminals are covered by this 

category. Emissions are based on the volume of gasoline transported and are affected 

by temperature and volatility. Some gasoline may go through bulk plants before 

distribution to service stations. For this reason gasoline throughput figures are adjusted 

by a factor of 1.25 to estimate total gasoline transported. 

Emission factors for transit losses were developed from Table 5.2-5 of AP-422. 

Statewide and countywide ADVMT information was obtained from IDOT’s 2002 Illinois 

Travel Statistics22. County gasoline usage was estimated by apportioning statewide 

gasoline consumption to the county level by VMT. Emissions are calculated using the 

following formula: 

E = GALgas * EFgas + GALetoh * EFetoh / 1000 / 2000 (4.10) 

 Where E = emissions (tons/year) 

 GALgas = gallons of gasoline used 

 EFgas = emission factor for gasoline (lb VOM/1000 gallons) 

 GALetoh = gallons of ethanol blend used 

 EFetoh = emission factor for ethanol blend (lb VOM/1000 gallons) 

65 
Table 4-41: Tank Truck Leak Emission Factors (lb VOM/1000 gallons) 

Area of the State Gasoline Ethanol 

Chicago NAA 0.16 --- 

Metro-East NAA 0.19 0.24 

Northern 0.19 0.22 

Southern 0.22 0.24 

Daily emissions are calculated using an activity adjustment factor of 0.0032 and a 

seasonal adjustment factor of 1.1. Emissions in the nonattainment townships are based 

on the percentage of VMT of the township to the whole county. 

Table 4-42: Gasoline Tank Truck Leak Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.60 171.12 

DuPage 0.15 42.66 

Grundy Twps 0.00 0.88 

Kane 0.06 16.98 

Kendall Twps 0.00 1.09 

Lake 0.10 29.09 

McHenry 0.04 10.26 

Will 0.08 22.08 

Chicago NAA 1.04 294.16 

Jersey 0.00 1.41 

Madison 0.06 16.53 

Monroe 0.01 2.01 

St. Clair 0.06 15.77 

Metro-East NAA 0.13 35.72 

Attainment Area 0.89 268.20 

State Total 2.05 598.08 

4.3.13.4 Underground Storage Tank Breathing 

Underground storage tank breathing losses include evaporation of gasoline vapors from 

the storage tank and from the lines going to the pumps during the transfer of gasoline. 

Emissions are also due to changes in temperature and barometric pressure. Emission 

are based on gasoline throughput and affected by gasoline temperature and volatility. 

A requirement of the Chicago and Metro-East 15% ROP was to install pressure vacuum 

relief valves on all underground gasoline storage tanks. Installation of these valves was 

estimated to reduce emissions by 95 percent. 

Emission factors for transit losses were developed from Table 5.2-5 of AP-422

. 

Statewide and countywide ADVMT information was obtained from IDOT’s 2002 Illinois 

Travel Statistics22. County gasoline usage was estimated by apportioning statewide 

66 
gasoline consumption to the county level by VMT. Emissions are calculated using the 

following formula: 

E = GALgas * EFgas + GALetoh * EFetoh / 1000 / 2000 (4.11) 

 Where E = emissions (tons/year) 

 GALgas = gallons of gasoline used 

 EFgas = emission factor for gasoline (lb VOM/1000 gallons) 

 GALetoh = gallons of ethanol blend used 

 EFetoh = emission factor for ethanol blend (lb VOM/1000 gallons) 

Table 4-43: Underground Storage Tank Breathing Emission Factors 

(lb VOM/1000 gallons) 

Area of the State Gasoline Ethanol 

Chicago NAA 0.04 --- 

Metro-East NAA 0.04 0.05 

Northern 0.91 4.20 

Southern 0.97 4.09 

Daily emissions are calculated using an activity adjustment factor of 0.0032 and a 

seasonal adjustment factor of 1.1. Emissions in the nonattainment townships are based 

on the percentage of VMT of the township to the whole county. 

Table 4-44: Underground Storage Tank Breathing Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.10 31.94 

DuPage 0.02 7.96 

Grundy Twps 0.01 3.27 

Kane 0.01 3.17 

Kendall Twps 0.01 4.07 

Lake 0.02 5.43 

McHenry 0.01 1.92 

Will 0.01 4.12 

Chicago NAA 0.19 61.88 

Jersey 0.02 5.09 

Madison 0.01 2.98 

Monroe 0.00 0.36 

St. Clair 0.01 2.84 

Metro-East NAA 0.04 11.27 

Attainment Area 2.98 986.26 

State Total 3.21 1,059.41 

67 
4.3.14 Graphic Arts 

Graphic arts includes the printing of newspapers, books, magazine, fabrics, wall 

coverings and other materials. Five types of printing are used in the industry: 

letterpress, flexography, lithography, rotogravure and screen press printing. Graphic 

arts emissions are based on a per capita emission factor of 1.3 lb VOM/person23. The 

point source inventory includes graphic arts sources. Therefore, point source emissions 

were subtracted from gross graphic arts emission estimate derived using the per capita 

emission factor. All processes in the point source inventory that had an SCC of the 

format 405xxxxx were deemed to be graphic arts related processes. In situations where 

the point source emission total exceeds the gross area source emission estimate, the 

net area source emission estimate is zero. 

E = POP * EF / 2000 – PS (4.12) 

 Where E = emissions (tons/year) 

 POP = population 

 EF = emission factor (1.3 lb VOM/person/year) 

 PS = point source emissions (tons/year) 

According to Reference 1, graphic arts activity takes place five days per week uniformly 

throughout the year. This results in an activity adjustment factor of 0.00385 and a 

seasonal adjustment factor of 1.0. Applying these two adjustments results in emission 

estimates in tons per summer weekday. Emissions for the nonattainment townships 

were calculated using the percentage of the population for the applicable townships. 

Table 4-45: Graphic Arts Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 8.12 2,109.97 

DuPage 0.83 216.38 

Grundy Twps 0.00 0.00 

Kane 0.00 0.00 

Kendall Twps 0.08 20.69 

Lake 0.68 177.71 

McHenry 0.00 0.00 

Will 1.30 336.77 

Chicago NAA 11.01 2,861.52 

Jersey 0.05 14.21 

Madison 0.61 157.26 

Monroe 0.05 13.81 

St. Clair 0.58 150.19 

Metro-East NAA 1.29 335.47 

Attainment Area 6.59 1,703.80 

State Total 18.89 4,900.79 

68 
4.3.15 Incineration 

An incinerator is a device in which refuse is burned. All incinerators at industrial, 

commercial and institutional locations require a permit. Incinerators at residences also 

require a permit. It is very unlikely that a residence has an incinerator. Residential 

waste incinerators, if they do exist, would contribute an insignificant amount of 

emissions to the inventory. For these reasons, residential waste incinerators were not 

included in the inventory. 

While all incinerators require a permit, it is possible that small companies are not aware 

of the regulation and do not obtain a permit for their incinerator and therefore do no 

have their emissions included in the point source inventory. To account for this possible 

shortfall, incinerators at industrial/commercial/institutional sources have been 

calculated. Based upon the known incinerators and the methodology of calculating area 

source emissions, it is likely the emissions for this category are over-estimated. 

E = POP * WG * EF * MAF / 1000 / 2000 – PS (4.13) 

 Where E = emissions (tons/year) 

 POP = population 

 WG = waste generation rate (87 lb/1000 persons)1

 EF = emission factor from Table 4-46 

 MAF = methane adjustment factor3

 1 for CO and NOx 

 0.66 for VOM 

 PS = point source emissions (tons/year) 

Table 4-46: Incineration Emission Factors (lb ton/burned)3

Pollutant Emission 

Factor 

CO 10.0 

NOx 3.0 

VOM 3.0 

Reference 1 assumes waste incineration occurs seven days per week uniformly 

throughout the year for an activity adjustment factor of 0.00275 and a seasonal 

adjustment factor of 1.0. Incineration emissions are also partially accounted for in the 

point source inventory. In cases where the point source emissions exceeded the gross 

area source estimate, the net area source emissions were reported as zero. Emissions 

for the nonattainment townships where calculated using the population of the applicable 

township. 

69 
Table 4-47: Industrial/Commercial/Institutional Incineration Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 6.27 2,278.74 1.88 684.17 1.23 445.57 

DuPage 1.08 393.44 0.32 114.83 0.20 73.80 

Grundy Twps 0.01 2.87 0.00 0.86 0.00 0.57 

Kane 0.52 187.49 0.16 57.73 0.10 38.07 

Kendall Twps 0.04 13.24 0.01 4.10 0.01 2.69 

Lake 0.08 279.84 0.23 82.86 0.15 52.91 

McHenry 0.32 117.17 0.10 36.17 0.07 23.85 

Will 0.65 235.92 0.20 72.64 0.13 47.80 

Chicago NAA 8.96 3,508.72 2.90 1,053.37 1.88 685.26 

Jersey 0.02 8.07 0.01 2.85 0.01 1.88 

Madison 0.30 109.78 0.09 33.34 0.06 21.74 

Monroe 0.03 12.64 0.01 3.79 0.01 2.50 

St. Clair 0.28 102.73 0.09 31.36 0.05 19.92 

Metro-East NAA 0.64 233.22 0.20 71.34 0.13 46.04 

Attainment Area 4.18 1,520.87 1.29 469.89 0.84 306.56 

State Total 13.78 5,262.80 4.38 1,594.59 2.85 1,037.86 

4.3.16 Industrial Surface Coating 

The category of industrial surface coating includes the following categories24: 

• Appliances 

• Automobiles (new) 

• Electrical Insulation 

• Factory Finished Wood 

• Furniture and Fixtures 

• High-performance Maintenance Coatings 

• Machinery and Equipment 

• Marine Coatings 

• Metal Containers 

• Other Product Coatings 

• Other Special Purpose Coatings 

• Other Transportation Equipment 

• Sheet, Strip and Coil 

The vast majority of these categories have some corresponding emissions in the point 

source inventory so care must be taken not to double-count industrial surface coating 

emissions. The point source inventory includes all sources that are permitted. There is 

no emission threshold or cutoff for obtaining a permit in the case of industrial surface 

coating. However, sources that use less than 5000 gallons of coating and solvent per 

year are not required to obtain a permit. 

70 
For the categories above, the typical method of calculating emissions is using an 

employee-based emission factor (e.g., lb VOM/employee/year). A review of 

employment data by SIC/NAICS shows that many of the sources (and therefore 

emissions) are present in the inventory. For example, there are known to be no cases 

where automobiles or appliances are coated that do not have a permit and do not exist 

in the point source inventory. Most of the other categories have the same result. 

The EIIP methodology for the industrial surface coating sector was written in 1997 and 

the emission factors were developed in 1991. Coating formulation and technology has 

changed dramatically since then. In addition, new regulations have been enacted which 

have forced this change or add-on control equipment. The point source emissions for 

the industrial surface coating sector are deemed to be of high quality and are based on 

current technology, not data from over ten years prior. The emission factors in the EIIP 

document are out of date and using them in conjunction with the point source inventory 

would introduce large errors. For this reason, only the categories of High-performance 

Maintenance Coatings, Other Product Coatings and Other Special Purpose Coatings 

are included in this category. These categories were deemed to have the least overlap 

with point sources and had the advantage of being based on population rather than 

employment. 

Emissions were calculated using the following formula: 

E = POP * EF / 2000 (4.14) 

 Where E = emissions (tons) 

 POP = population 

 EF = emission factor from Table 4-48 (lb VOM/person/year) 

Table 4-48: Industrial Surface Coating Emission Factors (lb VOM/person/year)24

Coating Category Emission 

Factor 

High-performance Maintenance 0.8 

Other Product 0.6 

Other Special Purpose 0.8 

Industrial surface coating operations are assumed to take place five days per week 

uniformly throughout the year. This results in an activity adjustment factor of 0.00385 

and a seasonal adjustment factor of 1.0. Applying these two adjustments results in 

emission estimates in tons per summer weekday. Emissions for the nonattainment 

townships were calculated using the percentage of the population for the applicable 

townships. 

71 
Table 4-49: Industrial Surface Coating Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 22.77 5,915.26 

DuPage 3.92 1,017.05 

Grundy Twps 0.03 7.26 

Kane 1.88 487.35 

Kendall Twps 0.14 35.02 

Lake 2.86 742.34 

McHenry 1.18 305.48 

Will 2.37 615.85 

Chicago NAA 35.14 9,125.61 

Jersey 0.09 24.04 

Madison 1.11 287.55 

Monroe 0.12 31.96 

St. Clair 1.09 283.69 

Metro-East NAA 2.41 627.24 

Attainment Area 15.80 4,107.81 

State Total 53.35 13,860.66 

4.3.17 Marine Vessel VOL Loading and Transport 

This category includes the emissions of VOM that occur from the loading and transport 

of volatile organic liquid (VOL) such as gasoline and crude oil onto and from ships and 

barges. This category does not include emissions from the combustion of fuels in the 

vessel’s engine. Those emissions are included in the off-highway mobile source 

category. Categories inventoried include: 

• VOL Loading Losses 

• Ship and Barge Transport 

• Tanker Ballasting 

• Barge and Tanker Cleaning 

Statistics regarding quantities of petroleum and petroleum products loaded and 

transported on state waterways for the 1990 inventory was taken from both the Army 

Corps of Engineer’s Waterborne Commerce of the United States25 and the Illinois 

Department of Transportation report Illinois Waterborne Shipping Database27. Due to 

the relatively small amount of emissions generated by this category, the emissions were 

estimated using growth factors based on the increased statewide use of gasoline from 

1990 to 2002. The 1990 statewide gasoline usage value was 4.441 billion gallons and 

the 2002 value was 5.212 billion gallons. This equates to a 17.4 percent increase. 

Therefore, a multiplier of 1.174 was applied to the 1990 emissions for each of the four 

categories. 

One of the ROP measures enacted in the Chicago and Metro-East areas was the 

required control of the summertime loading of gasoline and crude oil. This regulation 

requires terminals to capture and destroy 95 percent of all emissions generated by such 

72 
loading operations. An alternative compliance option does not require the installation of 

vapor recovery equipment if the facility agrees not to load such products during the 

ozone season. Loading operations are sufficiently large enough to obtain a permit so all 

of the emissions are included in the point source inventory. Also, since no permit 

applications have been submitted for any non-point source loading operations, it can be 

assumed the affected sources are choosing to comply with the regulation by ceasing 

any summertime loading. 

The emissions for the Metro-East area were used to approximate emissions for the 

other counties along the Mississippi River. These emissions were calculated using the 

ratio of the amount of shoreline for the county to be calculated to the amount of 

shoreline for Monroe County. Since daily emissions were calculated, annual emissions 

were calculated assuming six days per week of operation and 52 weeks per year. 

Table 4-50: Marine Vessel VOL Loading and Transport Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.35 109.20 

DuPage 0.00 0.00 

Grundy Twps 0.02 6.24 

Kane 0.00 0.00 

Kendall Twps 0.00 0.00 

Lake 0.00 0.00 

McHenry 0.00 0.00 

Will 0.36 90.48 

Chicago NAA 0.73 227.76 

Jersey 0.06 18.72 

Madison 0.48 149.76 

Monroe 0.09 28.08 

St. Clair 0.02 6.24 

Metro-East NAA 0.65 202.80 

Attainment Area 1.64 511.68 

State Total 3.02 942.24 

4.3.18 Open Burning 

Open burning is the burning of materials in outdoor areas such as forests, prairies, 

yards and farmlands that are set intentionally. This category does not include material 

burning in dedicated combustion devices nor does it include emissions from forest fires 

or structure fires. Emissions from prescribed burning, residential household waste and 

yard waste combustion are included in this inventory. 

4.3.18.1 Prescribed Burning 

Prescribed burning takes place when fire is intentionally set to a forest or land (e.g., 

prairie). The total number of acres burned, 2735, was obtained from USEPA16. This 

73 
value was apportioned to the county level by the number of acres of forest, scrub and 

grass acreage. The emission factor used was for non-piled material. 

Emissions were calculated using the following formula: 

E = ACRES * CF * (1 + SF) * EF / 2000 (4.15) 

 Where E = emissions (tons/year) 

 ACRES = number of acres burned 

 CF = consumption factor (3 tons burned/acre burned) 

 SF = smoldering factor (0.083) 

 EF = emission factor from Table 4-51 (lb/ton burned) 

Table 4-51: Prescribed Burning Emission Factors (lb/ton material burned)16

Pollutant Emission 

Factor 

CO 289 

NOx 6.2 

VOM 13.6 

Emissions for the nonattainment townships were calculated using the percentage of 

land area for the applicable townships. It was assumed that prescribed burning took 

place in the spring and fall and not in the ozone season. 

Table 4-52: Prescribed Burning Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 30.53 0.00 0.66 0.00 1.44 

DuPage 0.00 15.42 0.00 0.33 0.00 0.73 

Grundy Twps 0.00 0.15 0.00 0.00 0.00 0.01 

Kane 0.00 12.67 0.00 0.27 0.00 0.60 

Kendall Twps 0.00 0.35 0.00 0.01 0.00 0.02 

Lake 0.00 4.24 0.00 0.09 0.00 0.20 

McHenry 0.00 12.26 0.00 0.26 0.00 0.58 

Will 0.00 15.38 0.00 0.33 0.00 0.72 

Chicago NAA 0.00 90.99 0.00 1.95 0.00 4.28 

Jersey 0.00 11.29 0.00 0.24 0.00 0.53 

Madison 0.00 23.87 0.00 0.51 0.00 1.12 

Monroe 0.00 13.72 0.00 0.29 0.00 0.65 

St. Clair 0.00 18.93 0.00 0.41 0.00 0.89 

Metro-East NAA 0.00 67.80 0.00 1.45 0.00 3.19 

Attainment Area 0.00 1,125.27 0.00 24.15 0.00 52.95 

State Total 0.00 1,284.07 0.00 27.55 0.00 60.42 

74 
4.3.18.2 Residential Household Waste 

This category includes material generated as waste at residences that is burned in 

something other than a device meant to incinerate the waste. Illinois law prohibits all 

burning except for landscape waste (i.e., leaves and branches). Even though there is a 

law prohibiting burning of this type of waste outdoors, this does occur. A rule 

effectiveness of 95 percent has been assumed. It is further assumed that waste 

generated at industrial, commercial and institutional sources do not perform open 

burning of waste. 

Emissions were calculated using the following formula: 

E = RPOP / 1000 * LF * EF * (1 – RE) (4.16) 

 Where E = Emissions (tons/year) 

 RPOP = rural population 

 LF = loading factor (450 tons material burned/1000 rural population)16

 EF = emission factor from Table 4-53 (lb/ton of ton of material burned) 

 RE = rule effectiveness (0.95) 

Table 4-53: Residential Household Waste Combustion Emission Factors 

(lb/ton material burned)16

Pollutant Emission 

Factor 

CO 85 

NOx 6 

VOM 30 

The rural population was estimated based on the rural percentage of the population 

from the 2000 Census. Emissions for the nonattainment townships were calculated 

using the percentage of the population for the applicable townships. It was assumed 

that this activity took place uniformly throughout the year which results in an activity 

adjustment factor of 0.00275 and a seasonal adjustment factor of 1.0. 

75 
Table 4-54: Residential Household Waste Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 0.00 0.00 0.00 0.00 0.00 

DuPage 0.00 0.00 0.00 0.00 0.00 0.00 

Grundy Twps 0.00 0.93 0.00 0.07 0.00 0.33 

Kane 0.00 0.00 0.00 0.00 0.00 0.00 

Kendall Twps 0.01 3.00 0.00 0.21 0.00 1.06 

Lake 0.00 0.00 0.00 0.00 0.00 0.00 

McHenry 0.00 0.00 0.00 0.00 0.00 0.00 

Will 0.00 0.00 0.00 0.00 0.00 0.00 

Chicago NAA 0.01 3.93 0.00 0.28 0.00 1.38 

Jersey 0.01 4.89 0.00 0.35 0.01 1.73 

Madison 0.00 0.00 0.00 0.00 0.00 0.00 

Monroe 0.01 4.72 0.00 0.33 0.01 1.67 

St. Clair 0.00 0.00 0.00 0.00 0.00 0.00 

Metro-East NAA 0.02 9.61 0.00 0.68 0.01 3.40 

Attainment Area 1.15 415.05 0.09 29.31 0.41 146.43 

State Total 1.18 428.58 0.09 30.27 0.42 151.21 

4.3.18.3 Yard Waste 

This category includes the open burning of leaves and brush at residences. Many cities 

prohibit the open burning of this type of waste, however, this was not accounted for in 

the calculation which results in emissions being overestimated. 

Emissions were calculated using the following formula16: 

E = RPOP * FF * WG * AF * PCTB * (EFB + EFL) (4.17) 

 Where E = Emissions (tons/year) 

 RPOP = rural population 

 FF = forested factor (0, 0.5, or 1) 

 WG = waste generation rate (0.538 lb/day/person) 

 AF = activity adjustment factor, percent burned on-site (0.28) 

 PCT = percent burned (0.25 for brush and leaves) 

 EF = emission factor from Table 4-55 (lb/ton of ton of material burned) 

Table 4-55: Yard Waste Combustion Emission Factors (lb/ton material burned)16

Type of 

Waste 

Pollutant Emission 

Factor 

Brush CO 140 

VOM 19 

Leaves CO 112 

VOM 28 

76 
The rural population was estimated based on the rural percentage of the population 

from the 2000 Census. It was assumed that burning leaves and brush takes place only 

in the spring and fall and does not take place during the ozone season. 

Table 4-56: Yard Waste Combustion Emissions 

County CO 

(tpd) 

CO 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.00 0.00 0.00 0.00 

DuPage 0.00 0.00 0.00 0.00 

Grundy Twps 0.00 0.00 0.00 0.00 

Kane 0.00 0.00 0.00 0.00 

Kendall Twps 0.00 3.54 0.00 0.66 

Lake 0.00 0.00 0.00 0.00 

McHenry 0.00 0.00 0.00 0.00 

Will 0.00 0.00 0.00 0.00 

Chicago NAA 0.00 3.54 0.00 0.66 

Jersey 0.00 5.79 0.00 1.08 

Madison 0.00 0.00 0.00 0.00 

Monroe 0.00 11.18 0.00 2.08 

St. Clair 0.00 0.00 0.00 0.00 

Metro-East NAA 0.00 16.97 0.00 3.16 

Attainment Area 0.00 328.11 0.00 124.65 

State Total 0.00 688.62 0.00 128.38 

4.3.19 Pavement Markings 

Pavement markings include highway painting of centerlines, edge stripes and 

directional marking and painting of bridges. 

Illinois’ portion of traffic paint usage in was estimated by multiplying the percentage of 

on-road and highway spending to the national paint usage data obtained from the Paint 

and Allied Products report (MA325F(20)-1)7

. An average application rate of 12.28 

gallons per road lane mile was obtained by dividing the total Illinois road lane miles by 

the total amount of paint usage. The EIIP for pavement markings27 gives a VOM 

content of 3.36 lb VOM/gallon. This yields an emission factor of 44.26 lb VOM/lane 

mile/year. This value was multiplied by the lane mileage obtained from the IDOT Office 

of Planning and Programming11. 

Pavement marking coatings were one of the categories included in the USEPA’s 

architectural and industrial maintenance coatings national rule. This regulation limited 

the VOM content of traffic marking paints to 150 grams per liter. This equates to a 63.7 

percent reduction in VOM content and emissions. 

77 
E = LM * EF * (1-CE) / 2000 (4.18) 

 Where E = Emissions (tons/year) 

 LM = lane miles (miles) 

 EF = emission factor (44.26 lb VOM/lane mile/year) 

 CE = control efficiency (0.637) 

It was assumed that activity took place five days a week for an activity adjustment factor 

of 0.00385 and that all painting took place between April and October for a seasonal 

adjustment factor of 1.72. Emissions for the nontattainment townships was based on 

the percentage of road miles in the township. 

Table 4-57: Pavement Marking Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.90 135.60 

DuPage 0.25 37.34 

Grundy Twps 0.01 0.82 

Kane 0.16 24.08 

Kendall Twps 0.01 0.69 

Lake 0.21 32.46 

McHenry 0.11 16.77 

Will 0.22 33.63 

Chicago NAA 1.86 281.38 

Jersey 0.02 2.38 

Madison 0.13 19.54 

Monroe 0.02 2.55 

St. Clair 0.12 18.23 

Metro-East NAA 0.29 42.70 

Attainment Area 3.30 497.89 

State Total 5.45 821.97 

4.3.20 Portable Fuel Containers 

Portable fuel containers (e.g., gasoline cans) are used to transfer small amounts of fuel 

from the purchasing point to the point of use. This fuel is then used to power 

commercial and residential off-highway vehicles and equipment. 

Emissions from portable fuel containers reach the atmosphere in various ways. These 

are identified as follows: 

• Permeation - liquid movement through the container out to the atmosphere 

• Diurnal – emissions from the fluctuation of the daily temperature 

• Spilling during transport of the container 

• Spilling during filling of the container 

• Vapor displacement losses during filling 

78 
Emissions were calculated using the California Air Resources Board methodology28

using the same ratios as California. This results in the following formula: 

E = CANS * (EFp + EFd + EFts + EFrs + EFvd) / 2000 (4.19) 

 Where E = emissions (tons/day) 

 CANS = number of fuel containers 

 Efp = emission factor for permeation (lb/can/day) 

 Efd = emission factor for diurnal emissions (lb/can/day) 

 Efts = emission factor for transport spillage (lb/can/day) 

 Efrs = emission factor for refueling spillage (lb/can/day) 

 Efvd = emission factor for vapor displacement (lb/can/day) 

The particular values used for the emission factors can be found in the following 

sections. It was assumed that commercial and residential operations 250 days per 

year. 

4.3.20.1 Commercial 

The population of fuel containers in a county was based upon the same ratio of 

commercial to residential containers as CARB times the number of residential fuel 

containers in a county calculated for Illinois. 

Table 4-58: Commercial Portable Fuel Container VOM Emission Factors (lb/can/day)28

Type of Emissions Emission Factor 

Permeation 0.0014 

Diurnal 0.0178 

Transport Spillage 0.0089 

Refueling Spillage 0.0014 

Vapor Displacement 0.00047 

Emissions for the nonattainment townships were calculated using population. 

79 
Table 4-59: Commercial Portable Fuel Container Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 1.68 420.95 

DuPage 0.28 69.43 

Grundy Twps 0.00 0.52 

Kane 0.11 28.55 

Kendall Twps 0.01 2.09 

Lake 0.18 46.12 

McHenry 0.08 19.06 

Will 0.14 35.72 

Chicago NAA 2.48 622.43 

Jersey 0.01 1.73 

Madison 0.09 21.74 

Monroe 0.01 2.19 

St. Clair 0.08 20.64 

Metro-East NAA 0.19 46.30 

Attainment Area 1.23 310.36 

State Total 3.90 979.09 

4.3.20.2 Residential 

The population of fuel containers was estimated based upon the number of occupied 

housing units in each county. 

Table 4-60: Residential Portable Fuel Container Emission Factors (lb VOM/can/day)28

Type of Emissions Emission Factor 

Permeation 0.0015 

Diurnal 0.0128 

Transport Spillage 0.0007 

Refueling Spillage 0.0014 

Vapor Displacement 0.00047 

Emissions for the nonattainment townships were calculated using the population. 

80 
Table 4-61: Residential Portable Fuel Container Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 14.96 3,741.02 

DuPage 2.47 617.00 

Grundy Twps 0.02 4.60 

Kane 1.01 253.74 

Kendall Twps 0.07 18.52 

Lake 1.64 409.88 

McHenry 0.68 169.42 

Will 1.27 317.49 

Chicago NAA 22.12 5,531.68 

Jersey 0.06 15.34 

Madison 0.77 193.20 

Monroe 0.08 19.47 

St. Clair 0.73 183.45 

Metro-East NAA 1.64 411.46 

Attainment Area 11.04 758.14 

State Total 34.80 8,701.28 

4.3.21 Solvent Cleaning 

Solvent cleaning operations are those that employ non-aqueous solvents to remove 

grease, fats, oil, was or other impurities from the surface of metal, glass or plastic 

articles that are to be further processed. Degreasing is conducted in a variety of 

industries with three basic cleaning designs used: small cold cleaning operations, open 

top vapor degreasers and conveyorized degreasers. These solvent cleaning operations 

can also be included in the point source inventory. Process with an SCC of 401002xx 

and 401003xx were deemed to be solvent cleaning emissions. 

The number of employees were obtained from Reference 16. In 1999, Illinois EPA 

adopted a regulation limiting the vapor pressure of solvents used in cold cleaning to two 

millimeters of mercury. This was estimated to reduce VOM emissions by 33 percent. 

Emissions were calculated using the following formula: 

E = EMP * EF / 2000 – PS (4.20) 

 Where E = emissions (tons/year) 

 EMP = number of employees 

 EF = emission factor from Table 4-62 (lb/employee/year) 

 PS = point source emissions (tons/year) 

81 
Table 4-62: Solvent Cleaning Emission Factors (lb VOM/employee/year)29

Type of 

Industry 

Emission 

Factor 

SIC 37xx 24 

All others 87 

Solvent cleaning operations are assumed to take place six days per week uniformly 

throughout the year. This results in an activity adjustment factor of 0.0032 and a 

seasonal adjustment factor of 1.0. Applying these two adjustments results in emission 

estimates in tons per summer weekday. Emissions for the nonattainment townships 

were calculated using the percentage of the population for the applicable townships. In 

cases where the point source emission component was larger than the calculated area 

source component, a value of zero emissions was used for the area source component. 

Table 4-63: Solvent Cleaning Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 13.49 4,203.11 

DuPage 3.56 1,108.37 

Grundy Twps 0.01 2.90 

Kane 1.58 491.51 

Kendall Twps 0.10 31.24 

Lake 1.95 609.00 

McHenry 0.99 307.58 

Will 0.81 250.82 

Chicago NAA 22.48 7,004.53 

Jersey 0.01 1.61 

Madison 1.02 317.74 

Monroe 0.01 3.93 

St. Clair 0.32 100.57 

Metro-East NAA 1.36 423.85 

Attainment Area 11.98 3,732.33 

State Total 35.82 11,160.71 

4.3.22 Structure Fires 

Annual structural fire data for 2002 was obtained from the Illinois State Fire Marshall’s 

Office30. Guidance and emission factors from the EIIP document for structure fires31

was used to calculate emissions. The number of fires were apportioned to each county 

based on the number of structures in each county. 

Emissions were calculated using the following formula: 

82 
E = FIRES * FL * EF / 2000 (4.21) 

 Where E = emissions (tons) 

 FIRES = number of fires in a given period 

 FL = fuel loading factor (1.5 tons burned per fire)31

 EF = emission factor from Table 4-64 (lb/ton burned) 

Table 4-64: Structure Fire Emission Factors (lb/ton material burned)31

Pollutant Emission 

Factor 

CO 60 

NOx 1.4 

VOM 11 

The number of fires in the ozone season for a particular county was calculated using the 

values from Table 18.3-2 in the EIIP document for structure fires31. 

Table 4-65: Structure Fire Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 2.71 188.62 0.06 4.40 0.50 34.58 

DuPage 0.44 30.84 0.01 0.72 0.08 5.65 

Grundy Twps 0.00 0.22 0.00 0.01 0.00 0.04 

Kane 0.19 13.41 0.00 0.31 0.04 2.46 

Kendall Twps 0.02 1.01 0.00 0.03 0.00 0.19 

Lake 0.30 20.99 0.01 0.49 0.06 3.85 

McHenry 0.13 8.92 0.00 0.21 0.02 1.63 

Will 0.25 17.18 0.01 0.40 0.05 3.15 

Chicago NAA 4.04 281.20 0.09 6.56 0.76 51.55 

Jersey 0.01 0.82 0.00 0.02 0.00 0.15 

Madison 0.14 9.94 0.00 0.23 0.03 1.82 

Monroe 0.01 1.01 0.00 0.02 0.00 0.18 

St. Clair 0.14 9.54 0.00 0.22 0.03 1.75 

Metro-East NAA 0.30 21.31 0.00 0.49 0.06 3.90 

Attainment Area 2.09 143.09 0.00 3.37 0.28 26.25 

State Total 6.43 445.60 0.09 10.42 1.09 81.70 

4.3.23 Waste Water Treatment 

4.3.23.1 POTWs 

POTWs are facilities that treat waste water by physical, biological and occasionally 

chemical methods such that wastewater can be discharged with a minimum of 

environmental harm. POTWs treat nearly all of an area’s domestic sewage and often 

83 
much industrial waste and storm sewer runoff as well. Although domestic and storm 

waste can contain minute amounts of VOM, virtually all emissions come from VOMs 

present in the industrial waste portion of the POTWs influent stream. POTWs are 

generally designed so that wastewater is treated biologically (activated sludge or other 

aerobic processes). It is assumed that most of the wastewater VOM is emitted during 

these treatment processes, but some VOMs may be destroyed, hence not emitted, by 

the biological and chemical activity that occurs in the various POTW processes. 

A number of theoretical studies32-36 of VOM emissions from POTWs have been 

conducted, but their conclusions tend to be inconsistent because of contradictory 

presumptions. The discrepancies occur because it is not generally known: 

• To what degree the flow in a POTW is “acclimated”; that is, to what degree the 

microorganisms responsible for the biodegradation of wastes in the flow are 

adapted to varying concentrations of various waste substances 

• Whether there was an accounting for “non-listed” VOM species in the 

wastewater. Listed compounds are from the list of 126 common substances 

compiled by USEPA that are toxic to humans (and to most microorganisms) 

hence their wastewater concentrations, and not specifically non-listed compound 

concentrations, are monitored at POTWs. 

An important study the Illinois EPA has reference is the one conducted by Noll and 

DePaul33. Its conclusions appear to address POTW VOM air emissions most accurately 

but only if a high degree of acclimation is assumed. The methods finally used by the 

Illinois EPA were developed after considering several different theoretical studies and 

one actual monitoring study. 

Emissions are calculated using Equation 4.22 derived from the Noll-DePaul data on the 

relationship between influent industrial flow and influent listed VOMs. Further 

background can be found in Reference 9. 

 E = (1.1207 x MGD x %IND/100 +2.10352) x 8.5774 x 0.00275 (4.22) 

 Where E = emissions (tons/day) 

 MGD = influent flow rate (million gallons per day) 

 %IND = percent industrial load 

Influent flow rates were obtained from discharge monitoring report data obtained from 

the Bureau of Water. Reported values for June, July and August were averaged to 

obtain the influent flow rate for the ozone season. The percent industrial load was 

assumed to be the same as the value used for the 1999 periodic inventory. 

84 
Table 4-66: POTW Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 2.55 930.93 

DuPage 0.29 107.85 

Grundy Twps 0.00 0.00 

Kane 0.15 55.73 

Kendall Twps 0.05 20.27 

Lake 0.31 114.28 

McHenry 0.05 19.49 

Will 0.06 25.36 

Chicago NAA 3.46 1,273.91 

Jersey 0.00 0.00 

Madison 0.13 50.15 

Monroe 0.00 0.00 

St. Clair 0.22 80.77 

Metro-East NAA 0.35 130.92 

Attainment Area 2.34 885.55 

State Total 6.15 2,290.38 

4.3.23.2 Industrial Waste Water Treatment Facilities 

Emissions from IWWTs were calculated using the same methodology as POTWs. In 

this case, the percent industrial load is assumed to be 100 percent. Only those facilities 

determined to have VOMs in their waste water were included in the calculations. 

Sources with influent flow rates less than 2 million gallons/day were summed per county 

and treated as a single flow. 

Table 4-67: Industrial Waste Water Treatment Emissions 

County VOM 

(tpd) 

VOM 

(tpy) 

Cook 0.43 157.64 

DuPage 0.09 33.47 

Grundy Twps 0.05 17.32 

Kane 0.05 21.17 

Kendall Twps 0.00 0.00 

Lake 0.09 35.51 

McHenry 0.13 49.78 

Will 0.59 216.33 

Chicago NAA 1.43 531.22 

Jersey 0.00 0.00 

Madison 0.50 183.37 

Monroe 0.00 0.00 

St. Clair 0.09 34.05 

Metro-East NAA 0.59 217.42 

Attainment Area 4.89 1,876.85 

State Total 6.91 2,625.49 

85 
4.3.24 Biogenic Emissions 

Biogenic emissions are those from flora such as trees, shrubs and crops. Emissions 

occur as the plant transpires, mostly during the daylight hours, and often in response to 

environmental stresses. Emission also occur from microbial activity in soils, often due 

to the breakdown of fertilizer. 

To meet the requirements of the CERR, USEPA calculated biogenic emissions using 

BEIS 3.12. These emission estimates were made available to the states. Daily 

emissions were calculated by taking the calculated monthly emissions for MaySeptember and dividing by the number of days in that period, 153. 

Table 4-68: Biogenic Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 4.04 759.94 0.86 216.31 46.07 7,898.37 

DuPage 3.04 531.83 0.68 166.18 37.05 6,124.02 

Grundy Twps 0.58 100.88 0.25 64.23 3.04 13.11 

Kane 3.69 611.57 1.34 317.34 35.05 5,697.48 

Kendall Twps 0.42 71.88 0.17 40.99 2.75 8.63 

Lake 3.11 585.44 0.71 172.12 30.32 5,241.29 

McHenry 3.68 614.50 1.20 279.47 35.09 5,726.26 

Will 5.19 912.40 1.63 425.88 47.34 7,958.49 

Chicago NAA 23.74 4,188.44 6.83 1,682.52 236.71 38,667.67 

Jersey 4.00 768.31 1.11 272.11 38.08 6,848.07 

Madison 4.46 858.82 1.44 345.44 34.17 6,220.00 

Monroe 4.06 799.21 1.14 281.81 32.66 6,024.95 

St. Clair 4.03 788.31 1.26 307.84 30.70 5,648.83 

Metro-East NAA 16.56 3,214.65 4.95 1,207.20 135.62 24,741.85 

Attainment Area 396.43 72056.68 147.06 35,883.20 2,653.75 465,173.71 

State Total 436.73 79,459.76 158.84 38,772.91 3,026.08 528,583.23 

86 
5 Mobile Sources 

A mobile source of air pollution is a self-propelled or portable emitter of air pollutants, 

and mobile source emissions are those generated by the engines or motors that power 

such sources. Most mobile sources except jet or turboprop aircraft are powered by 

internal combustion (IC) piston engines, and nearly all use liquid fuels. Gaseous fuels, 

such as compressed natural gas (CNG) or liquefied petroleum gas (LPG), had only a 

very small fraction, barely 0.1 percent, of the motor fuel market in Illinois in 2002. Solid 

fuels have not been used by mobile sources in significant amounts since railroads 

retired their coal-powered steam locomotives in the 1950s. 

5.0.1 Categories of Mobile Sources 

For inventory and planning purposes, mobile sources are divided into two major 

categories. 

1. On-highway mobile sources, i.e., motor vehicles such as cars, vans, trucks, 

buses and motorcycles used for transportation of goods and passengers on 

roads and streets 

2. Off-highway (usually referred to as non-road) mobile sources including: 

• Modes of powered transportation that do not use roads, such as aircraft, 

trains, ships and boats, and motor vehicles used off-road; and 

• Self-propelled or portable motorized machines or equipment not used for 

transportation, ranging from construction equipment and farm tractors to 

lawnmowers and hand-held power weed choppers. 

All on-highway mobile sources are self-propelled. Some nonroad mobile sources (e.g., 

farm tractors), are self-propelled, but many nonroad sources are not. A gasolinepowered chain saw is a familiar example of a non-self-propelled nonroad mobile source. 

Not all movable or portable emission sources are mobile sources, however. A small 

truck-portable cement or hot-mix asphalt plant, for example, may be set up near a 

construction or road-building site. Such plants are classified as stationary sources, not 

mobile sources for two reasons: (1) they may operate for weeks or months at a single 

location, and (2) the trucks that move the plants do not supply power for them. 

Not all IC or turbine engines are mobile sources. Fixed IC engines, such as those that 

power pipeline compressors or standby generators in electricity plants and elsewhere, 

are also classified as stationary sources. 

87 
5.0.2 Categories and Components of Mobile Source Emissions 

There are three categories of mobile source emissions: 

• Exhaust or tailpipe emissions, which result from the combustion of fuel in the 

source’s engine 

• Evaporative emissions, which result from evaporation of fuel from the engine or 

its fuel system; and 

• Refueling emissions 

Exhaust emissions are the result of fuel combustion and occur only when the engine is 

running. 

Evaporative emissions are VOM only and are continuously emitted from an engine’s 

fuel system, whether the engine is running or not. Gasoline is a very volatile fuel, so 

total VOM emissions from gasoline powered vehicles have a large evaporative 

component. Diesel and jet fuels are of very low volatility, so evaporative emissions from 

diesel and turbine engines are a much smaller part of their total VOM emissions. 

Evaporative emissions for CNG or LPG powered vehicles are negligible because their 

fuel tanks and systems are, of necessity, sealed. Evaporative and exhaust VOM 

emissions can be calculated separately for most mobile source categories, but in this 

inventory these two components are combined into total VOM. Evaporative emissions 

do not include VOM emissions that occur during refueling. 

Refueling emissions are a third category of mobile source emissions. Refueling 

emissions are entirely VOM. Although they result from the evaporation of fuel, they are 

distinct from, and not directly related to, evaporative emissions as defined above. 

Refueling emissions have two subcomponents: 

• Displacement emissions. Occur when new fuel is transferred into a partly filled 

tank (be it a service station storage tank, a portable fuel container or gas can, or 

a vehicle or engine’s fuel tank), displacing the air in the tank and forcing that 

vapor-rich air out the inlet pipe or other vent. There are two stages of 

displacement emissions: 

o “Stage I” emissions occur when the underground storage tanks at a 

service station are being refilled; 

o “Stage II” emissions occur when a motor vehicle (or gas can) is being 

refueled. 

• Spill emissions. These occur when drops of fuel drip or splash on the ground 

during or after refueling and evaporate away. 

Refueling emissions from on-highway sources occur almost entirely at commercial or 

private service stations. For many years, service stations in the Chicago and MetroEast areas and certain other counties in Illinois have been required to have equipment 

that captures Stage I emissions and recycles them to the tank truck delivering the fuel. 

Stage II emissions can be controlled by devices at the pump (“Stage II vapor recovery” 

equipment) or on the vehicle (“on-board [vapor] recovery”, OB[V]R) that capture and 

recycle the displacement emissions before they are emitted to the air. Stage II vapor 

88 
recovery equipment has been required at service stations in the Chicago area since the 

1980s. OBVR equipment is required by federal regulation on new light-duty vehicles: 

cars from model year 1998 on, and light trucks from model year 2001 on. 

Non-road sources also have refueling emissions. Some non-road sources, especially 

locomotives and many aircraft and boats, are refueled at fixed locations, the functional 

equivalents of motor vehicle service stations. However, many small non-highway 

sources (e.g., lawnmowers) are refueled where they are used from mobile or portable 

tanks or fuel containers. In this inventory, refueling emissions from non-road categories 

(except aircraft refueling) are not reported separately from exhaust and evaporative 

emissions, but rather are included in the reported overall non-road VOM emissions. 

Refueling emissions from motor vehicles are reported separately from exhaust and 

evaporative emissions, though not in this chapter. Stage I emissions from service 

stations and refueling, and Stage II emissions from motor vehicles, are both considered 

area source VOM emissions and are discussed in more detail in Chapter 4. Estimates 

of on-highway refueling emissions are given in Section 4.3.13 “Gasoline Marketing“. 

Emissions from refueling of aircraft are in Section 4.3.2 “Aircraft Refueling”. 

5.1 On-Highway Mobile Source Inventory 

The inventory of on-highway mobile source emissions contains Illinois EPA’s estimates 

of the amounts of CO, NOx and VOM from highway vehicles statewide by county. 

Exhaust and evaporative VOM emissions are combined. Emissions are reported for a 

typical ozone season weekday in the summer of 2002 in accordance with USEPA’s 

guidance. The estimates given here are for on-highway sources do not include 

refueling emissions. Refueling emissions are found in the Area Sources chapter. 

5.1.1 On-Highway Mobile Source Emissions Summary 

Table 5-1 is a summary of the on-highway mobile source emissions of CO, NOx and 

VOM in tons per summer weekday and tons per year. Detailed tables of on-highway 

mobile source emissions are given in the appendices. 

89 
Table 5-1: On-Road Mobile Source Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 1,198.67 56,467.51 235.99 97,482.66 97.00 34,356.84 

DuPage 297.38 140,757.49 58.32 24,300.13 24.20 8,564.30 

Grundy Twps 7.57 2,582.88 1.88 410.16 0.61 158.03 

Kane 124.67 59,150.04 25.17 9,755.43 10.13 3,605.61 

Kendall Twps 8.73 2,977.74 1.26 504.58 0.74 181.80 

Lake 201.08 96,410.08 37.28 16,582.01 16.53 5,866.53 

McHenry 75.81 36,262.38 14.61 5,911.07 6.27 2,211.00 

Will 162.40 76,406.01 34.37 12,673.69 13.15 4,655.86 

Chicago NAA 2,076.43 979,219.14 408.88 167,619.73 168.63 59,599.97 

Jersey 12.21 5,109.41 1.68 609.79 1.02 380.91 

Madison 127.64 54,833.20 23.27 7,877.35 10.83 3,859.66 

Monroe 17.94 7,439.08 2.55 976.75 1.37 521.51 

St. Clair 123.22 52,361.54 19.57 7,519.49 10.35 3,683.91 

Metro-East NAA 281.01 119,743.24 47.07 16,983.38 23.57 8,445.99 

Attainment Area 2,348.05 1,066,794.52 404.31 125,265.82 203.12 75,449.84 

State Total 4,705.48 2,165,756.89 860.26 309,868.93 395.32 143,495.81 

5.1.2 Inventory Guidance and References 

The following publications provide much of the guidance for the preparation of this onhighway inventory. 

• EPA-450/4-81-026d (Revised), now EPA/450-R-92-009, Procedures for Emission 

Inventory Preparation, Volume IV: Mobile Sources, December 1992. Hereafter 

“Procedures Vol. IV”. The 1992 version is still the definitive document on 

inventories. If a previous edition is referred to, the fact will be noted as, for 

example, “the 1989 Procedures Vol. IV” or “Volume IV, 1989 edition”. 

• EPA420-R-03-010, User’s Guide to MOBILE6.1 and MOBILE6.2: Mobile Source 

Emission Factor Model, August 2003. This is the User’s Guide for the official 

MOBILE6.2.03 on-highway mobile source emission factor model and will usually 

be referred to as the M6.2 (or simply M6) User’s Guide (UG). Emission factors 

calculated by this model were used in this inventory as discussed in more detail 

below. User’s Guides for previous versions of the MOBILE6 model were used 

during the preliminary work on this inventory. The M6 model in its various 

versions was developed and published by Assessment & Modeling Division 

(AMD) of the National Vehicle & Fuels Emissions Laboratory (NVFEL) in Ann 

Arbor, Michigan. The NVFEL is part of USEPA’s Office of Transportation & Air 

Quality (OTAQ), formerly the Office of Mobile Sources (OMS). 

• Technical Guidance on the Use of MOBILE6 for Emission Inventory Preparation, 

August 2004. Hereafter, referred to as the M6 “Technical Guidance [Document]” 

or “TGD”. The TGD is the primary source of guidance on M6 inputs and an 

invaluable adjunct to the M6 User’s Guide. 

90 
• USEPA document “Frequently Asked Questions on MOBILE6”, 16 January 2002. 

Hereafter, referred to as [M6] “FAQ”. This document was published along with 

the M6 TGD. 

• USEPA memo, “Policy Guidance on the Use of MOBILE6 for SIP Development 

and Transportation Conformity”, dated 18 January 2002, from John Seitz, 

Director of OAQPS, and Margo Oge, Director of OTAQ, to Regional Air Division 

Directors. 

• EPA420-R-03-001, MOBILE6.1 Particulate Emission Factor Model Technical 

Description: Final Report, January 2003, and EPA420-R-02-011, Draft Report 

Technical Description of MOBILE6.2 and Guidance for Its Use for Emission 

Inventory Preparation, February 2002. These documents outline how 

MOBILE6.1 and 6.2 calculate particulate and air toxics emission factors. 

• EPA-AA-AQA-94-1, User’s Guide to MOBILE5 (Mobile Source Emission Factor 

Model), May 1994. This document covers both the MOBILE5a and MOBILE5b 

models and, although it is no longer a primary reference now that MOBILE5b has 

been superseded by MOBILE6, it still has useful information on mobile source 

emissions modeling. 

• EPA-454/R-07-004d, EIIP Volume IV: Mobile Sources: Preferred and Alternative 

Methods, July 1997. This is one of seven volumes of inventory guidance 

published by the Emission Inventory Improvement Program (EIIP). EIIP Vol. IV 

is composed of three chapters: 

o Chapter 1: “Preferred and Alternative Methods for Gathering and Locating 

Specific Emission Inventory Data”, June 1996. This chapter includes 

instructions for estimating registration and mileage accumulation data, 

vehicle miles traveled (VMT), fuel consumption, etc., from I/M program 

information. 

o Chapter 2: “Use of Locality-Specific Transportation Data for the 

Development of Mobile Source Emission Inventories”, September 1997. 

This chapter includes instructions for estimating locality-specific MOBILE 

inputs and for estimating future VMT from transportation model output. 

o Chapter 3: “Guidance for Estimating Lawn & Garden Equipment Activity 

Levels”, September 1997 

• Conformity Analysis Documentation Appendix B: Travel Demand Modeling for 

the Conformity Process in Northeastern Illinois” from the 2020 Regional 

Transportation Plan: Transportation Improvement Program for Northeastern 

Illinois: FY 1998-2002, published in November 1997 by the Chicago Area 

Transportation Study (CATS), the metropolitan planning organization (MPO) for 

the Chicago area. This document contains much information on CATS’s traffic 

modeling process and traffic in the Chicago area. Hereafter, referred to as 

“CATS Appendix B”. 

91 
• Emissions Inventory Guidance for Implementation of Ozone and Particulate 

Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze 

Regulations, Draft document published June 2003 by USEPA/OAQPS and 

abbreviated EIG. See also its predecessor of the same name, EPA-454/R-99-

006, April 1999. 

5.1.3 Basic Concepts of On-Highway Mobile Source Emission Inventories 

5.1.3.1 Vehicle Types 

Emissions are reported for eight vehicle types corresponding to the vehicle types for 

which the MOBILE emission factor model normally reports emission factors. The 

vehicle types are described in more detail in Table 5-2. 

Table 5-2: Inventory Vehicle Types in MOBILE6 

Inventory 

Vehicle 

Type Vehicle Type Description 

Corresponding 

MOBILE5 

Vehicle Type 

LDGV Light-duty gasoline powered vehicles – passenger cars, 

including station wagons. Some small SUVs and vans 

are in this category. 

LDGV 

LDGT12 Light-duty gasoline powered trucks types 1 & 2 – small 

trucks up to 6,000 lb GVW, consisting of M6 vehicle types 

LDGT1 (LVW < 3,750 lb) and LDGT2 (LVW between 

3,750 and 6000 lb). Most pickups, small vans and SUVs 

are in this category. 

LDGT1 

LDGT34 Light-duty gasoline powered trucks – larger trucks 

between 6,000 and 8,500 lb GVW, consisting of M6 

vehicle types LDGT3 (ALVW < 5,750 lb) and LDGT4 

(ALVW > 5,750 lb). Typical of this category are delivery 

vans and large SUVs. 

LDGT2 

HDGV Heavy-duty gasoline powered vehicles – larger vans, 

trucks and buses, GVW > 8,500 lb, consisting of eight M6 

HDGV weight classes (2b, 3, 4, 5, 6, 7, 8a and 8b) and 

gasoline buses (HDGB). 

HDGV 

LDDV Light-duty diesel powered vehicles – diesel passenger 

cars. 

LDDV 

LDDT Light-duty diesel powered trucks – diesel trucks up to 

8,500 lb GVW, including diesel pickups, vans, delivery 

vehicles, etc. This small category consists of M6 vehicle 

types LDDT12 and LDDT34 (cf. the two LDGT types) 

defined the same as the corresponding gasoline truck 

types. 

LDDT 

92 
Table 5-2: Inventory Vehicle Types in MOBILE6 (continued) 

Inventory 

Vehicle 

Type Vehicle Type Description 

Corresponding 

MOBILE5 

Vehicle Type 

HDDV Heavy-duty diesel vehicles – large diesel trucks and 

buses. GVW > 8,500 lb, including large trucks, tractortrailers and diesel buses, and consisting of eight M6 

HDDV weight classes (2b, 3, 4, 5, 6, 7, 8a and 8b, 

defined the same as the corresponding gasoline truck 

types) and two diesel bus types (HDDBT [transit buses] 

and HDDBS [school buses]). 

HDDV 

MC On-road motorcycles. All are gasoline powered. Offroad motorcycles are treated as recreational vehicles in 

the non-road category. 

MC 

Different types of vehicles have different emission characteristics. Larger and heavier 

vehicles emit more than smaller, lighter vehicles using the same fuel. Generally 

speaking, diesel vehicles also emit less CO and VOM but more NOx than their gasoline 

equivalents. 

5.1.3.2 Classifications of Roads 

Public roads are classified according to their function in the highway system. The 

Federal Highway Administration’s Highway Performance Monitoring System (HPMS), 

the most widely used classification, defines twelve functional classes (FCs) of roads as 

in Table 5-3. In this inventory, daily emissions are estimated for each of the twelve 

HPMS functional classes. 

Table 5-3: HPMS Functional Classes of Roads and Their Codes 

Functional Class Abbreviation Code 

Rural Interstates R-Int 01 

Rural Other Principal Arterials R-OPA 02 

Rural Minor Arterials R-MA 06 

Rural Major Collectors R-MaC 07 

Rural Minor Collectors R-MiC 08 

Rural Local Roads R-Lcl 09 

Urban Interstates U-Int 11 

Urban Other Freeways and Expressways U-OFE 12 

Urban Other Principal Arterials U-OPA 14 

Urban Minor Arterials U-MA 16 

Urban Collectors U-C 17 

Urban Local Streets U-Lcl 19 

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The way in which people drive on different types of roads, referred to as “driving cycles”, 

resulting in different on-road emission characteristics. A car driven ten miles on urban 

local streets, with a low average speed, frequent stops and starts at intersections emits 

more than when it driven the same distance at a steady moderate speed on a freeway 

without any stops. Moreover, a vehicle will have different emission characteristics on 

different road types even if the average speed is the same in both cases. 

MOBILE6 is the first MOBILE model to take different driving cycles explicitly into 

account. M6 calculates emission factors for four facility types (FTs): freeway, arterials 

and connectors, local roads and streets, and freeway ramps corresponding to four 

driving cycles (DCs) whose emission characteristics are built into the model. The 

emission factor the model reports in its descriptive output is the weighted average of the 

individual emission factors for the four driving cycles, the weighting factors being the 

fractions of total VMT for each facility type. MOBILE6’s default file FVMT.DEF, hourly 

fraction of VMT by the four facility types, has the standard weighting factors used for 

that purpose. The user can replace the FVMT file with an external VMT-by-FT file that 

reflects area-specific conditions. Illinois EPA has developed VMT-by-FT files for the 

Chicago and Metro-East areas in this inventory, using transportation modeling data 

supplied by CATS and EWGCC. The default VMT-by-FT file is used for areas outside 

the two NAAs. Illinois EPA has developed VMT-by-FT files that assign all the VMT to a 

single facility type. This is used to obtain emission factors for the individual facility 

types. 

MOBILE6’s four facility types are matched to the twelve HPMS functional classes in 

Table 5-4 as in TGD Table 4.2.1, p. 29. See M6 TGD, §4.2.2 for a more detailed 

discussion of M6 facility types and driving cycles. 

Table 5-4: MOBILE6 Facility Types or Driving Cycles 

MOBILE6 FT or DC FT or DC VMT in Terms of 

HPMS Functional Class VMT 

Freeways (freeways and 

expressways) 

92 percent of the sum of VMT 

from R-Int, U-Int, R-OPA and 

U-OFE 

Arterials (arterials and 

collectors) 

Sum of VMT from R-MA, RMaC, R-MiC, R-Lcl, U-OPA, UMA and U-C 

Locals (local roads and streets) VMT from U-Lcl 

Ramps (freeway ramps) 8 percent of the sum of VMT 

from R-Int, U-Int, R-OPA and 

U-OFE 

Freeway driving is characterized by high speeds and few stops and takes place mostly 

on limited-access roads. Arterial driving is characterized by moderate speeds and 

occasional stops. Much in-town driving is of this nature. Local driving is characterized 

94 
by slow average speeds and frequent stops and takes place chiefly on neighborhood 

streets and small rural roads. Ramp driving is characterized by rapid accelerations and 

decelerations as vehicles enter or leave high-speed traffic on freeways. 

Virtually all the traffic takes place on paved roads. Dirt roads have very little traffic and 

are not common, even in rural areas. 

5.1.3.3 Activity Factors and Emission Factors 

On-highway emissions for the vehicle types or categories are estimated in essentially 

the same way as point and area emissions are. For a given pollutant, emissions are 

given by the following equation. 

 E = AF × EF × CF (5.1) 

 where: 

 E = emission rate for that particular pollutant 

 AF = activity factor 

 EF = emission factor for that particular pollutant 

 CF = conversion factor to obtain emissions in desired units 

For motor vehicles, the activity factor can be expressed as output (e.g., distance 

traveled) or input (e.g., amount of fuel used) per unit time. The activity factor of choice 

for estimating on-highway exhaust and evaporative emissions is distance traveled, but 

the preferred activity factor for estimating on-highway refueling emissions is fuel 

consumption derived from data on fuel sales. The emission factor must be in units 

corresponding to those of the activity factor (i.e., mass of pollutant per unit distance or 

fuel amount). In this inventory, the on-highway activity factor is typically daily VMT. 

Illinois EPA used the MOBILE6.2 model to estimate the on-highway emission factors for 

this inventory, as required by USEPA (67 FR 4254, 29 January 2002). The version of 

MOBILE6 used in this inventory is 6.2.03 (24 September 2004), which became the 

USEPA’s official model (69 FR 28830, 19 May 2004) for estimating emissions of 

hydrocarbons, carbon monoxide, oxides of nitrogen, particulate matter and air toxics 

from highway vehicles on its formal release in February 2004. 

Equation 5.1 is simple, but the actual emission estimating process is more complex. An 

accurate emission inventory is not the result of multiplying a total area-wide VMT by 

some single average all-vehicle emission factor to obtain an emission value for a given 

pollutant. There are two reasons for this: 

95 
• Emission factors generated, especially for CO and VOM, are very sensitive to 

vehicle speed and the relationship between speed and emission factor is not 

linear. 

• Different vehicle types have different emission characteristics and therefore 

different emission factors. 

Different road types have different average speeds. Thus, M6 emission rates for a 

vehicle type on freeways are different from those on local roads or streets. Roads of a 

given type also have different average speeds under different traffic conditions. Speeds 

are lower during rush-hour congestion than during free traffic flow at 4 AM. It is difficult, 

therefore, to estimate a priori a single speed that would be representative of all the 

traffic in a whole county or region for a whole day. However, reasonably accurate 

speed estimates can be made for various functional classes or for individual segments 

or “links” on a transportation model network. Emissions by functional class or by link 

can then be calculated and summed to obtain regional emissions. 

USEPA requires emissions to be reported separately for each of the eight vehicle types 

in Table 5-2. The shares of the total VMT generate by each vehicle type, VMT 

fractions, are used to calculate the VMT by vehicle type (VT) according to the formula: 

 VMTVT = Total all-vehicle VMT × VMT FractionVT (5.2) 

The VMT for a vehicle type is multiplied by the emission rate for the vehicle type to give 

emissions for that vehicle type. The vehicle-type emissions are then summed to obtain 

total emissions for all vehicle types. 

Region-wide activity factors and emission factors must both be broken down into 

spatial, temporal and other components and each activity factor multiplied by its 

corresponding emission factor to get component emission estimates on at least a byvehicle-type basis. The process of breaking down activity factors and emission factors 

into components is called “disaggregation.” The disaggregated emissions, calculated 

from disaggregated components, are summed to get emissions on a county or regional 

basis. This is best expressed by rewriting Equation 5.1 as: 

CFE )EF(AF (5.3) C

C last

C first

×= ∑ C ×

Since the activity factor is the VMT from Equation 5.3, we can rewrite as: 

×= ∑( × × (5.4)

C last

C first

C all CFE VMT Total C Fraction VMT C EFC )

where the subscript C refers to the component(s) into which the activity factors (i.e., 

VMT and VMT fraction) and emission factors have been disaggregated, such as county 

or link or functional class of road, or even time of day. Since there are usually several 

96 
components or levels of disaggregation, there may actually be several summations to 

be completed before the total emissions for the whole region or state is calculated. 

Representative region-wide VMT mixes are hard to estimate accurately, but reasonably 

accurate VMT mixes by functional class or even network link are often available, or can 

be made, from data supplied by transportation agencies. 

The VMT fractions used to calculate emissions in this inventory are shown in Table 5-5 

below. They are derived from IDOT vehicle count monitoring data collected during 

2002. The all-vehicle VMT mix in Table 5-5 is the most representative VMT mix for the 

State as a whole. The VMT fractions in Table 5-5 are closely related to, but are not the 

same as, the VMT fractions used as inputs to the MOBILE model. See the MOBILE 

inputs section below for more information on VMT fractions used with the MOBILE 

model. 

Table 5-5: Statewide Average VMT Mixes 

HPMS HPMS V e h i c l e T y p e 

Code Functional Class (FC) LDGV LDGT12 LDGT34 HDGV LDDV LDDT HDDV MC 

01 Rural Interstate 0.3558 0.2342 0.0799 0.0968 0.0006 0.0013 0.2254 0.0060 

02 Rural OPA 0.4542 0.2989 0.1021 0.0408 0.0007 0.0016 0.0957 0.0060 

06 Rural Minor Art 0.4657 0.3065 0.1046 0.0337 0.0008 0.0017 0.0810 0.0060 

07 Rural Major Collectors 0.4779 0.3145 0.1074 0.0270 0.0008 0.0017 0.0647 0.0060 

08 Rural Minor Collectors 0.4993 0.3287 0.1121 0.0137 0.0008 0.0018 0.0376 0.0060 

09 Rural Local Roads 0.4886 0.3216 0.1099 0.0197 0.0007 0.0018 0.0517 0.0060 

11 Urban Interstate 0.4577 0.3013 0.1030 0.0385 0.0008 0.0016 0.0911 0.0060 

12 Urban OEF 0.4803 0.3161 0.1080 0.0258 0.0008 0.0017 0.0613 0.0060 

14 Urban OPA 0.4843 0.3187 0.1089 0.0230 0.0008 0.0017 0.0566 0.0060 

16 Urban Minor Arts 0.4879 0.3212 0.1097 0.0207 0.0008 0.0017 0.0520 0.0060 

17 Urban Collectors 0.4942 0.3253 0.1110 0.0180 0.0008 0.0018 0.0429 0.0060 

19 Urban Local Streets 0.5092 0.3351 0.1145 0.0092 0.0008 0.0018 0.0234 0.0060 

Overall VMT Mix 0.4676 0.3078 0.1051 0.0327 0.0008 0.0017 0.0783 0.0060 

Overall Rural VMT Mix 0.4330 0.2850 0.0973 0.0525 0.0007 0.0016 0.1239 0.0060 

Overall Urban VMT Mix 0.4819 0.3173 0.1083 0.0245 0.0008 0.0017 0.0595 0.0060 

Different combinations of emission control strategies (scenarios) will give rise to efferent 

emission factors. The difference in the emission factors for various scenarios is used to 

calculate the emission reductions arising from them. Illinois EPA estimates and reports 

emission reductions from its vehicle inspection and maintenance (I/M) program in this 

manner, by comparing emission factors for a no-I/M scenario with those from an I/M 

scenario. 

97 
As noted above, the activity factor used in this inventory is VMT. VMT in a region is the 

total number of miles driven by all the vehicles operating in the region over a given 

period of time. Statewide average daily VMT (ADVMT) in Illinois was about 291 million 

miles per day in 2002. 

5.1.3.3.1 IDOT VMT Estimates for the Emission Inventory 

The VMT estimates used to calculate emissions for this inventory are those made and 

published by the Office of Planning and Programming (OPP) of the Illinois Department 

of Transportation (IDOT). Illinois EPA uses IDOT’s VMT data because those data are 

official, complete, easy to work with and of high quality. IDOT has general oversight of 

all transportation matters in Illinois. Other organizations that estimate VMT are CATS 

and the East-West Gateway Coordinating Council (EWGCC), the metropolitan 

[transportation] planning organizations (MPOs) for the Chicago and St. Louis areas, 

respectively. 

IDOT and the MPOs use complementary methods of estimating VMT. IDOT uses 

observed traffic count data as input to a program to estimate annual VMT by county and 

by functional class for the entire State. These estimates are the “Roadway File” VMT 

estimates for a given year and are the State’s official published VMT estimates for that 

year. The Federal Highway Administration (FHWA) receives a subset of the Roadway 

File that meets the statistical requirements of the HPMS. CATS and EWGCC, on the 

other hand, use zone-based travel-demand transportation models to estimate VMT in 

their planning regions, and validate their estimated traffic against observed traffic 

counts. IDOT and the MPO’s methods are described in more detail below. Despite 

their difference in methodologies, the estimates of VMT in their regions are close. The 

VMT estimates, made by different methods, thus act as checks on one another, 

ensuring the correctness of the emission estimates made from them. 

Illinois EPA requested, and received, from IDOT/OPP a copy of IDOT’s 2002 Roadway 

File, plus VMT estimates by functional class for the nonattainment townships in Kendall 

and Grundy Counties. Illinois EPA also requested and received adjustment factors for 

converting ADVMT to Average Summer Weekday VMT (ASWVMT) or to monthly VMT, 

as required for the inventory. 

The MPO’s transportation model output data, being link-based, are more spatially 

detailed than IDOT’s Roadway File. IDOT’s Roadway File data are based largely on 

actual observed 2002 transportation information and are calculated every year. This is 

not necessarily the case with the transportation model outputs. 

The VMT estimates submitted by IDOT to the FHWA under the HPMS are a subset of 

the Roadway File VMT estimates. The statewide Roadway File VMT is larger than the 

HPMS VMT, but only by about 0.12 percent. The two estimates are identical for all 

functional classes except rural local roads and urban local streets. The difference 

arises because roadway file VMT estimates cover all roads in the state, including some 

98 
1600 miles of private local roads that HPMS VMT does not include; and IDOT uses all 

available reliable traffic count and other data, while HPMS, by its nature, uses a smaller 

sample. The difference between the Roadway File and the HPMS VMTs translates into 

less than a ton of NOx or VOM statewide. Illinois EPA uses IDOT’s Roadway File data 

in preference to HPMS data in emission estimates because: 

• IDOT’s Roadway File VMT data by county and nonattainment township are 

readily available to Illinois EPA in a convenient and usable form tailored to Illinois 

EPA’s needs 

• IDOT’s Roadway File VMT estimates are more comprehensive and hence 

slightly more conservative than HPMS data. IDOT’s Roadway File VMT 

estimates are made from larger samples and so are internally more consistent 

and statistically more robust then HPMS VMT. 

• USEPA approved the use of IDOT Roadway File data when it approved Illinois 

EPA’s 1990 Emission Inventory, in which IDOT data for 1990 were used in the 

estimation of on-highway emissions, along with the Transportation Model output 

data from CATS and EWGCC. USEPA has also approved Illinois EPA’s use of 

Roadway File data in subsequent inventories. 

Since IDOT supplies complete VMT data by county (or township) and functional class 

for the entire NAA and the entire state, there is no need for volume group tables or 

expansion factors such as would have been necessary had Illinois EPA been using 

HPMS data, and no such tables or factors have been included in this document. Also, 

there is no need to estimate NAA VMT from HPMS data for the FHWA [Federal Aid] 

“Urbanized Area” which was usually much smaller than the NAA that it was part of. 

From IDOT’s original 2002 Roadway File VMT data (annual VMT by county and 

functional class), Illinois EPA computed ADVMT for each county and for the three 

nonattainment townships by functional class. Those ADVMT estimates are summarized 

in Table 5-6. 

99 
Table 5-6: Summary of ADVMT 

Area/County 2002 ADVMT 

Chicago NAA 

 Cook 93,634,920 

 DuPage 23,341,008 

 Grundy NAA Twps 391,090 

 Kane 9,290,976 

 Kendall NAA Twp 538,859 

 Lake 15,916,146 

 McHenry 5,616,598 

 Will 12,083,239 

Metro-East NAA 

 Madison 7,601,343 

 Monroe 925,001 

 St. Clair 7,254,116 

Rest of Illinois 114,319,836 

State Total 290,912,439 

5.1.3.3.2 How IDOT Estimates VMT 

IDOT’s VMT estimates for a given year are based on the latest traffic counts taken for 

each of the roadway segments. IDOT’s traffic count procedures are documented in its 

“Illinois Traffic Monitoring Program” publication. The short-term (24-hour) coverage 

count is the primary source of traffic data for the Department’s Traffic Monitoring 

Program. It is not possible to make traffic counts on every road every year, so counts 

are made at intervals or cycles at various locations for at least 24 (sometimes 48 or 

more) hours at a time. These cycles are different for different types of roads. 

Some 5,000 to 6,000 counts are made on the Marked Route System (Interstates, and 

US and Illinois routes) every two years on the odd-number years (1999, 2001, 2003, 

etc.). IDOT receives annual traffic data from the Interstate freeways in the Chicago 

Area yearly from its Traffic System Center. The Illinois State Toll Highway Authority 

supplies similar data for the tollways. 

The Unmarked System (county highways, township roads, etc.) in each county is 

counted on a five year cycle, with approximately a fifth of the counties being counted 

each year. Some 15,000 to 20,000 counts are made each year on the Unmarked 

System. The county coverage counts make up the majority of the traffic counts made in 

the State. Counts made on Unmarked Routes for HPMS purposes are made on a 4-

year cycle. 

Since 2001, IDOT has been using magnetic lane counters to collect traffic volume and 

vehicle classification by length on the Marked Route System. Between 1999 and 2001, 

OPP purchased over a thousand such counters. Counting marked routes with magnetic 

100 
counters eliminates the need for separate surveys to determine heavy commercial and 

multiple-unit truck volumes. 

All the county-wide counts in IDOT District 1 (the six county Chicago area) are counted 

using the magnetic lane counters. In the rest of the state, the county-wide coverage 

count is a 24-hour count usually made with more conventional counters that use 

pneumatic tubes to count axles. These counts are adjusted by resources available. 

Further counts may be made on the local road system to better characterize local traffic 

as well. 

IDOT also receives local traffic count data collected by other sources, such as county 

and city traffic departments and MPOs. In each case, the counting procedures and the 

traffic count data undergo quality control reviews before the count data are accepted as 

valid and used in the VMT estimation process. 

Raw traffic data collected from actual counts are entered into a database and tables of 

seasonal adjustment factors based on information from continuous-count stations are 

used to adjust and round the counts to Average Daily Traffic. This information goes into 

IDOT’s Illinois Roadway Information System (IRIS) database. After all counts for the 

year have been processed and entered into IRIS, the count database is used to 

calculate VMT. 

The 2002 VMT calculations used traffic counts made over the previous four or five 

years. Counts made in 2002 were used where available. Where there were no 2002 

counts, counts from 2001 or previous years were used after they were grown to 2002 

using growth factors specific to each functional class. Road segments without a count 

(primarily local functional classes) were assigned an ADT equal to the weighted 

average ADT within that county and functional class if there was 70 percent or more 

coverage in the county; otherwise, a standard value was used. 

All of the processing was done through a series of queries to the database. The result 

was a 2002 ADT, based on actual 2002 count, grown previous year count or estimated 

default count, for every road segment in Illinois. The daily VMT for a segment is then 

the product of the calculated ADT for the segment and the length of the segment in 

miles. For example, a corrected adjusted ADT of 18,100 vehicles per day on a section 

of road 1.47 miles long give a daily VMT of 26,607 vehicle miles traveled per day. The 

VMTs of all the segments are then summed into State and county totals and functional 

class as needed. 

IDOT does considerable edit checking, review and analysis of its VMT data. Illinois 

EPA’s QA is limited to comparing the 2002 data with those from previous years and with 

similar data from FHWA to doubly ensure reasonableness and accuracy. IDOT 

provided the roadway file data to Illinois EPA in electronic form as a spreadsheet file. 

This eliminated the possibility of data entry errors. 

101 
IDOT maintains a continuous count program consisting of automatic traffic recorders 

placed in permanent locations along the roadway, generally as electromagnetic loops 

buried in the pavement. Hourly traffic data are collected and retrieved from these sites 

throughout the year. Automatic traffic recorder data supplement the short-term count 

data mentioned above and also provide the statistical information the IDOT uses to 

develop traffic growth factors for converting previous year counts to current year counts 

and the various factors to convert short-term counts to ADT. The automatic traffic 

recorder data area also used to calculate profiles of traffic from hour to hour during the 

day, from day to day during the week and from month to month during the year. The 

adjustment factors thus calculated and used in the inventory are statewide in nature. 

There are presently, as of 2004, 85 sites in the automatic traffic recorder network. Of 

these sites, 49 have been in place since 1988 and 36 were installed in 1999. There are 

now 43 sites in the Chicago area, eight in the Metro-East area and 41 elsewhere in the 

state. 

ADT estimates in the Chicago area are made for interstates, non-local roads and local 

roads and streets. As described above, interstates, including tollways, are the subjects 

of detailed counting. The Chicago NAA has about 412 miles of interstate highway, 

including tollways, or just under 19 percent of the approximately 2,170 miles of 

interstate in the whole of Illinois. There are traffic counts with sufficient density to 

determine traffic on about 95 percent of the 6,580 miles of non-local roads in the 

Chicago NAA. The method used is essentially the same as that for other short-term 

counts. Traffic on the remaining five percent of roads in the second category is 

estimated in the same manner as that described below for local roads. IDOT expects 

accuracy of ±10 percent for the ADT estimates for individual sections of interstates and 

most non-local roads. This means that some estimated ADT volumes are higher than 

actual volumes and others are lower, but on aggregate, the high and low estimates 

offset one another and the resulting regionwide and statewide estimates have much 

lower uncertainty. 

There are about 17,390 miles of local roads and local streets of the third category in the 

Chicago NAA. Most local streets are residential and are not generally modeled as links. 

Some counts are made on local roads and streets, but in most cases local traffic is 

estimated by using an average traffic density for local roads. These factors are areaspecific, being 1,083 daily VMT per mile for the Chicago Urbanized Area, for example. 

These factors were originally developed from randomly selected traffic counts a number 

of years ago, but like other traffic correction and estimation factors, they are periodically 

reviewed and have been revised upward in recent years. 

5.1.3.3.3 Adjusting VMT for Summer Weekday Conditions 

Illinois EPA uses IDOT’s Roadway File VMT data in the form of Average Daily VMT, 

that is, reported Annual VMT divided by 365. Traffic counts at continuous count stations 

show overall traffic in Illinois is higher than average in summer and lower than average 

in the middle of winter. In accordance with Procedures Vol. IV. § 3.4.2.6 and § 

102 
4.3.1.3.3, ADVMT data from IDOT were adjusted for seasonal variations in traffic by 

using adjustment factors by functional class from Table 5-7 below to get average 

summer weekday VMT (ASWVMT). 

These adjustment factors were calculated by IDOT from continuous count and other 

long term count data available and, for convenience, are expressed here as percents. 

They are specific to Illinois, applicable Statewide and are based on 2002-2003 traffic 

count data. They are the factors that IDOT divides into traffic counts made during a 

given month in order to estimate ADT, hence the name “Seasonal Division Factors.” 

Procedures Vol. IV, § 3.4.1.3.3 when discussing seasonal adjustments, makes 

reference to multiplicative factors used to adjust 24- and 48-hour traffic counts in 

various months to ADT; those factors are simply the reciprocals of those in Table 5-7. 

The seasonally adjusted VMT for a county is the sum of the products of county ADVMT 

by functional class and the appropriate adjustment factor for that functional class. For 

this inventory, a “typical summer weekday” VMT is desired, so the June, July and 

August factors are averaged. This June-July-August average is shown at the bottom of 

Table 5-7. 

The average (all functional class) summer weekday adjustment factor is determined by 

dividing the calculated total ASWVMT by its original ADVMT total. For the Chicago 

NAA, that factor is 1.096. The factor for the Metro-East NAA is 1.092 and 1.086 for the 

attainment counties. The statewide average is 1.092. These are slightly higher than 

the factors used in the past, based on late-1990s traffic data. 

Table 5-7: Weekday Seasonal Division Factors for Application to Weekday 

(Monday – Thursday) Traffic Counts 

Month 

Rural 

Interstates

Other 

Rural 

Functional 

Classes 

Urban 

Interstates

Other 

Urban 

Functional 

Classes 

January 0.83 0.85 0.93 0.95 

February 0.87 0.92 0.99 1.01 

March 0.94 0.98 1.02 1.06 

April 0.97 1.03 1.03 1.10 

May 1.00 1.03 1.04 1.12 

June 1.06 1.04 1.07 1.12 

July 1.08 1.09 1.07 1.11 

August 1.08 1.11 1.08 1.09 

September 1.00 1.06 1.04 1.08 

October 0.99 1.08 1.05 1.07 

November 0.99 1.03 1.04 1.04 

December 0.93 0.97 0.99 1.04 

June-July-August 

Average 

1.073 1.08 1.073 1.107 

103 
IDOT has similar factors for estimating monthly VMT from ADVMT. These factors were 

used to estimate VMT by month. The VMT-by-month data were used to estimate 

annual emissions of the various pollutants. The monthly factors, shown in Table 5-8, 

are applicable statewide and are specific to Illinois. Previous versions of the seasonal 

adjustment factors, covering earlier three-year periods are very similar to those given 

above. Detailed tables of Illinois VMT is in Appendix G. 

All these tables contain subtotals for the NAAs and attainment counties. The ADVMT 

and ASWVMT tables have VMT totals by county and by MOBILE6 facility type fractions. 

The statewide M6 facility type fractions are close to MOBILE6’s default fractions, but the 

facility type fraction for individual counties vary widely. Half a dozen very rural counties, 

for example, have no freeway VMT. On the other hand, 14 other rural counties, through 

which interstates pass, have freeway fractions over 50 percent because the bulk of their 

VMT is from traffic passing through the county on the interstate. Three of those 

counties have freeway fractions over 60 percent. 

Table 5-8: Monthly Factors to Convert ADVMT to Total Monthly VMT 

Rural Urban 

Month Interstates Other FCs Interstates Other FCs 

January 26.514 26.902 28.495 28.387 

February 24.850 24.844 26.802 26.160 

March 29.717 29.323 30.377 30.206 

April 29.661 30.069 29.877 30.972 

May 31.849 31.673 31.158 32.159 

June 32.469 31.944 31.296 32.028 

July 33.923 32.894 32.004 31.614 

August 34.444 33.930 32.965 32.132 

September 30.828 31.497 30.498 30.747 

October 31.236 31.543 31.518 30.696 

November 29.796 30.144 30.138 29.316 

December 29.704 30.234 29.878 30.588 

Annual 364.991 364.997 365.006 365.005 

June-August 100.836 98.768 96.265 95.774 

5.1.3.3.4 Emission Factors 

On-highway emission factors from the descriptive output of the MOBILE6.2 model are 

used in this inventory, in accordance with USEPA’s requirements. MOBILE6.2 is the 

most recent approved model in the series of MOBILE emission factor models developed 

by USEPA’s Office of Transportation & Air Quality (OTAQ). Illinois EPA uses the 

MOBILE 6.2.03 version which gives emission factors for CO, NOx, particulates, 

particulate precursors (SO2 and NH3) and VOM. MOBILE6.2 can also calculate 

emission factors for certain air toxics. That capability was not used in this inventory. 

104 
5.1.3.3.5 MOBILE6 Inputs for Inventory 

Every MOBILE6 input file must have at least seven commands: MOBILE6 INPUT 

FILE to start it, END OF RUN to end it, RUN DATA and SCENARIO RECORD to control it, 

and three parameters. The parameters are temperature (MIN/MAX TEMPERATURE), 

gasoline volatility (FUEL RVP) and CALENDAR YEAR of evaluation. Vehicle speed is 

not a required input to MOBILE6. There are, however, many options available to make 

an input file (and hence the output) more representative of specific areas and 

conditions, or to take into account various control programs, or to obtain output in 

greater or lesser detail. 

Table 5-9: MOBILE6.2 Inputs Used in this Inventory to Evaluate Summer Weekday 

Emission Factors 

Input Input Value or Short Description 

Evaluation Month & Calendar 

Year 

July 2002 

Maximum and Minimum Chicago & Northern Illinois – 84o F and 64o F 

Temperatures Metro-East & Southern Illinois – 89o F and 71o F 

Chicago & Northern Illinois – 97 gr/lb Absolute Humidity Metro-East and Southern Illinois – 108 gr/lb 

Chicago NAA – “Northern” Reformulated Gasoline 

Downstate – Ordinary gasoline (not RFG), RVP = 8.1 

Fuel Inputs psi, 30 percent gasohol 

Metro-East – Ordinary gasoline (not RFG), RVP = 7.2 

psi, 30 percent gasohol 

Refueling Emission Factors No. See below. 

Speed See Activity Inputs below 

I/M Program for light- and 

heavy-duty gasoline vehicles 

in Chicago and Metro-East I/M 

areas 

Program is centralized (i.e., at State testing stations), 

and test-only (no repairs done). Vehicles are tested 

every two years. The engine test consists of (a) an 

idle test for old (Model Year 1968 – 1980) cars & light 

trucks; (b) an IM240 test for newer (Model Year 1981 – 

1995) cars & light trucks, with cutpoints as in external 

file MYCUTS.D; (c) Exhaust & Evaporative OBD (onboard diagnostics) test for newest (Model Year 1996 

and later) cars & light trucks; (d) an idle test for Model 

Year 1968 and newer heavy-duty vehicles; and (e) a 

gas cap check for all vehicles. There is a 4-year notest grace period for new vehicles. 

The two NAAs – area-specific registration distributions 

based on data from Illinois EPA’s Division of Mobile 

Sources Registration Distribution 

Downstate outside the NAAs – MOBILE6 default 

105 
Table 5-9: MOBILE6.2 Inputs Used in this Inventory to Evaluate Summer Weekday 

Emission Factors (continued) 

Input Input Value or Short Description 

Chicago NAA – Chicago area specific VMT mix 

derived from data supplied by CATS VMT Fraction (VMT Mix) Downstate including Metro-East NAA – Illinois specific 

all functional class VMT mix 

Chicago and Metro-East NAAs – area specific activity 

input files derived from transportation model output 

data supplied by CATS and EWGCC 

Activity Inputs: VMT by 

functional class, hour and 

speed Downstate and outside the NAAs – M6 default activity 

input files (FVMT.D, HVMT.D and SVMT.D) 

Diesel Sulfur 375 ppm 

Particle Size 10 micrometers and 2.5 micrometers 

Particulate Emission Factor 

Input Files 

Those supplied with MOBILE6. 

Table 5-9 is a digest of the significant inputs used in the MOBILE6.2 model when 

evaluating summer weekday (daily) emissions. 

5.1.3.3.6 Refueling Inputs 

M6 runs to calculate refueling emission factors use the same inputs for fuel volatility, 

presence of RFG or oxygenates, etc. as for other inventory runs, but the temperature 

inputs are different. A summary of the inputs for refueling emission factors are given in 

Table 5-10. 

Table 5-10: Specialized MOBILE6 Inputs for Summer Weekday Refueling 

Emission Factors 

Input Input Value 

Start Year – 1992 

Phase-in – 3 years 

Efficiency for LDVs and LDTs – 84 percent 

Stage II Inputs 

(Chicago NAA only) 

Efficiency for HDVs – 84 percent 

All other inputs Same as those for “no refueling” inventory case given above 

As noted in § 5.0.3 above, service stations in the Chicago NAA are required to have 

Stage II vapor recovery equipment on their gasoline pumps. The Stage II inputs in 

Table 5-10 are specific to the Chicago NAA and appear following the STAGE II 

REFUELING command in the Run section of an input file for a Chicago NAA refueling 

run only. 

106 
5.1.4 Calculation of Daily Emissions 

A spreadsheet was used to calculate emissions for this inventory. The process is as 

follows. 

• Create a multi-page spreadsheet file. The name for this example is named 

ONHWY02. 

• Enter a table of ADVMT by county (vertically) and by functional class 

(horizontally) derived from IDOT’s Roadway File into the first page of ONHWY02. 

Include ADVMT totals for the attainment and nonattainment townships of Kendall 

and Grundy Counties for use in calculations pertaining to the Chicago NAA. 

• Using seasonal adjustment factors as described in § 5.1.3.1, compute a table of 

ASWVMT in the same form as the ADVMT table on a new page of ONHWY02. 

Give each of the rows of VMT information a range name. 

• Place the table of VMT mixes by vehicle type (vertically) and functional class 

(horizontally) on the third page. Each of the rows of VMT mixes is named for its 

vehicle type. 

• Run the MOBILE6.2 model using the inputs described above for six scenarios: 

1. Chicago inputs, assuming RFG and no I/M program 

2. Chicago inputs, assuming RFG and the I/M program described above 

3. Northern half of Illinois outside Chicago, assuming Chicago temperature 

inputs, but no RFG (only ordinary gasoline and 30 percent gasohol) and 

no I/M program 

4. Southern half of Illinois outside the Metro-East area, assuming St. Louis 

temperature inputs, no RFG, 30 percent gasohol and no I/M 

5. Metro-East inputs, assuming St. Louis temperatures, low volatility 

gasoline, 30 percent gasohol and no I/M 

6. Metro-East inputs as above, but with I/M as above 

Set the inputs to run each scenario five times, once with a representative VMT by 

facility type external file, and once each with a VMT by facility file that attributed 

all VMT to freeways, arterials, local roads and ramps, respectively. The resulting 

outputs for the facility type specific runs were therefore the emission factors for 

the freeway, arterial, local and ramp facility types, respectively. In this way, 

emission factors for CO, NOx and VOM were obtained for each scenario and all 

facility types. 

• Enter the emission factors by vehicle type into new pages (one for each facility 

type) of the spreadsheet by vehicle type (vertically) and functional class 

(horizontally) for each of the pollutants. The I/M emission factors for the Chicago 

and Metro-East areas are entered into their respective pages in the same form 

as the no-I/M factors, and the “I/M Credit” emission factors are calculated by 

107 
subtracting the I/M factors for the corresponding no-I/M factors. These factors 

are calculated to the right of the no-I/M emission factor table. 

• Set up a table of emissions by pollutant for a given county by functional class 

(horizontally) and vehicle type (vertically) on a new page that matches the 

emission factor table form. Emissions are then calculated using Equation 5.4. 

For this example, assume the calculation is for Adams County, rural interstate as 

the functional class, LDGV as the vehicle type and VOM as the pollutant. 

Emissions are calculated by taking the ASWVMT for rural interstate for Adams 

County times the LDGV VMT fraction for rural interstates times the LDGV VOM 

emission factor for rural interstate. In this case, the emissions are: 

130,915 miles/day × 0.3558 × 1.432 g/mile × 1.102x10-6 g/ton = 0.07 tons/day 

• Repeat the above step for each of the vehicle types and functional classes in the 

county and sum the results to get county total VOM by vehicle type and 

functional class. 

• Repeat the above step for the other pollutants of interest in the county. At the 

end of this step, the calculation of the county’s emissions by functional class and 

vehicle type for all pollutants is complete. 

• Repeat the previous three steps for the remaining 101 counties. 

Calculations for the NAA counties are a little more involved, but are made in similar 

fashion to those above. All or part of every county in an Illinois NAA is in an I/M area. 

Each county that is entirely within a NAA has three spreadsheet pages: a no-I/M 

emissions page, an I/M credits page and a Net Emissions page. The No-I/M and I/M 

credit pages for the NAA counties are calculated as describe above. Net emissions are 

simply the no-I/M emissions minus the I/M credits. 

With very few exceptions, gasoline vehicles registered at addresses within areas 

covered by I/M in the Chicago and Metro-East NAAs are subject to I/M. The VMT 

fractions for Cook, DuPage and Lake Counties are large, well over 90 percent, because 

the I/M area entirely covers those counties and all gasoline vehicles registered in them 

are subject to I/M. Those fractions are not quite 100 percent because there is a certain 

amount of traffic in the counties from gasoline vehicles registered outside the I/M area 

and therefore not subject to I/M. Other counties are not entirely within the I/M coverage 

area, so more VMT in those counties comes from vehicles not subject to I/M and their 

I/M fractions are smaller. 

Table 5-11 gives the I/M fractions that Illinois EPA uses when calculating I/M credits. 

These I/M fractions were estimated by Illinois EPA based on information from VIM and 

(for the Chicago NAA) transportation model output from CATS, and are the same 

fractions used in the approved 1999 inventory. Since the I/M area has not changed in 

area since these fractions were calculated, they have not changed significantly. 

108 
Table 5-11: I/M Fraction for Illinois Counties 

County I/M 

Fraction 

Chicago NAA 

 Cook 0.98 

 DuPage 0.98 

 Grundy NAA Twps 0.25 

 Kane 0.60 

 Kendall NAA Twp 0.81 

 Lake 0.95 

 McHenry 0.50 

 Will 0.65 

Metro-East NAA 

 Jersey 0.00 

 Madison 0.90 

 Monroe 0.20 

 St. Clair 0.90 

Downstate (all other counties and 

attainment townships for Grundy 

and Kendall) 

0.00 

5.1.5 Calculation of Annual Emissions 

USEPA recommends that annual emissions be calculated as the sum of 12 monthly 

emissions (using representative monthly emission factors and VMT). To accomplish 

this, Illinois EPA used a spreadsheet similar in form and format to the one used to 

calculate summer weekday emissions. The process steps employed are very similar to 

those for daily emissions. 

The first step is to estimate VMT for each month of the year by multiplying the ADVMT 

totals for each county by the number of days in the month. The second step is to obtain 

emission factors representative of each month. To do this, the MOBILE6.2 model was 

run twelve times, once for each month of the year, for each of the four areas of the state 

(Chicago, Downstate North, Downstate South and Metro-East), using average monthly 

temperature and fuel inputs. All Facility Type emission factors were calculated 

assuming the default distribution of VMT among facility types. This is a reasonable 

assumption since the statewide facility type fractions are quite close to the MOBILE6 

default fractions. 

109 
Table 5-12: Statewide Facility Type Fractions 

Facility 

Type 

Actual Statewide 

VMT Fraction 

(%) 

MOBILE6 

Default VMT 

Fraction (%) 

Freeway 31 34 

Arterial 54 50 

Local 12 13 

Ramp 3 3 

The MOBILE input for evaluation month and calendar year for each monthly run was set 

to either January 2002 (January – March), July 2002 (April – September) or January 

2003 (October – December). USEPA recommends output from those inputs be used as 

is for the monthly emission factors without interpolation. Annual emissions calculated 

this way are quite accurate because the small errors in the individual monthly emission 

factors caused by not interpolating will offset one another over the twelve months. 

The third step is to multiply the monthly VMT by the monthly all-vehicle emission factors 

to give monthly emissions and then sum those to obtain annual emissions. Monthly and 

annual I/M Credits are calculated in the same manner. 

5.2 Off-Highway Mobile Source Emissions 

This section of the 2002 inventory covers motorized modes of transportation that do not 

use roads as well as self-propelled or portable motorized machines or equipment not 

used for transportation. 

5.2.1 Estimating Off-Highway Emissions 

Off-highway emissions are estimated in the same way as on-highway emissions, 

namely, by multiplying together an activity factor, an emission factor and a conversion 

factor. The factors for on-highway emissions are straightforward – VMT and MOBILE6 

emission factors – and relatively easy to obtain in considerable detail. For non-road 

sources, surrogate data must often be used to estimate off-highway emissions. Those 

emissions must be apportioned to states, counties or NAAs in a reasonable fashion. 

The methods used to estimate emissions are discussed in the following sections. 

5.2.2 Off-Highway Modes of Transportation 

Off-highway modes of transportation include trains (i.e., locomotives), aircraft, ships and 

boats, and motor vehicles used off-road. Several factors make off-highway emissions 

important in Illinois. Illinois is at the heart of commercial aviation and the railroad 

110 
network in the United States and much of the waterborne commerce originates in or 

passes through Illinois waters. In particular, the Chicago and the St. Louis area are 

both major centers of air and rail traffic. O’Hare Airport in Chicago is the busiest in the 

world. Waterborne commerce on the Illinois and Mississippi Rivers and on Lake 

Michigan is considerable, and the state is well supplied with rivers and lakes where 

much recreational boating takes place. 

5.2.2.1 Railroad Locomotives 

Rail traffic in Illinois is powered almost entirely by diesel locomotives. Most rail traffic in 

Illinois is freight, but there are several major Amtrak passenger routes in Illinois and an 

extensive diesel-powered commuter rail network (METRA) centered on Chicago. The 

major (Class I) railroads – Burlington Northern, Santa Fe, Canadian National, Canadian 

Pacific, CSX, Kansas City Southern, Norfolk Southern and Union Pacific – all operate in 

Illinois, and most rail traffic is on their routes. There are also nearly 40 regional and 

short lines in the state. Most of these smaller railroads are very small – a few miles of 

track and an engine or two – but some have several hundred miles of track in the state 

and transport millions of tons of freight. Methods of estimating and apportioning 

locomotive emissions are discussed at some length in Procedures Vol. IV § 6.0. Using 

these and related methods, and under contract with LADCO on behalf of the Midwest 

states, the consulting firm Environ made estimates of locomotive emissions in 2002 for 

Illinois by county. Those estimates are given in Table 5-13. 

Table 5-13: Railroad Locomotive Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 5.48 2,001.17 50.40 18,396.40 2.25 820.63 

DuPage 1.16 423.28 10.54 3,848.66 0.45 163.18 

Grundy Twps 0.01 5.67 0.14 51.36 0.01 2.21 

Kane 0.44 159.65 3.95 1,441.46 0.16 60.22 

Kendall Twps 0.01 4.56 0.12 41.23 0.00 1.72 

Lake 0.22 78.83 1.95 712.43 0.08 30.16 

McHenry 0.14 52.35 1.29 471.41 0.05 19.85 

Will 1.53 558.95 13.78 5,028.85 0.58 212.95 

Chicago NAA 8.99 3,284.45 82.18 29,991.82 3.59 1,310.91 

Jersey 0.01 4.71 0.12 42.50 0.01 1.83 

Madison 0.02 7.97 0.21 78.20 0.01 3.00 

Monroe 0.30 108.71 2.67 973.87 0.11 40.83 

St. Clair 0.03 9.81 0.24 88.52 0.01 3.97 

Metro-East NAA 0.36 131.20 3.24 1,183.09 0.14 49.64 

Attainment Area 13.63 4,973.51 123.29 45,001.52 5.29 1,937.49 

State Total 22.98 8,389.16 208.71 76,176.43 9.02 3,298.04 

111 
5.2.2.2 Emissions from Aircraft Operations 

Powered aircraft emit exhaust and evaporative pollutants form their engines like other 

mobile sources. This inventory is concerned with the emissions occurring when aircraft 

are on or near the ground, i.e., within about 3,000 feet of the ground, that being the 

average summer morning mixing height of the atmosphere over Illinois (see 

“Procedures Vol. IV”, § 5.2.2, pp 145-149). Emissions which take place above 3,000 

feet or at cruising altitude are not, in general, found to contribute to the formation of 

ozone at ground level and are not part of this inventory. 

5.2.2.2.1 Summary of Aircraft Emissions in Illinois 

CO, NOx and VOM emissions from aircraft operations in Illinois are given below in 

Table 5-14. The estimates do not include emissions from auxiliary power units (APUs) 

on aircraft at Midway and O’Hare Airports in Chicago. APU emissions are identified in 

Table 5-17. 

Table 5-14: Aircraft Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 25.17 8,750.17 26.88 9,496.89 3.70 1,300.16 

DuPage 2.72 816.03 0.03 9.03 0.12 35.66 

Grundy Twps 0.00 0.00 0.00 0.00 0.00 0.00 

Kane 1.40 439.75 0.01 5.85 0.05 19.09 

Kendall Twps 0.00 0.00 0.00 0.00 0.00 0.00 

Lake 1.52 445.12 0.03 7.31 0.08 22.41 

McHenry 1.00 318.50 0.00 2.45 0.04 11.89 

Will 2.50 793.00 0.01 6.11 0.09 29.59 

Chicago NAA 34.31 11,562.57 26.96 9,527.64 4.08 1,261.83 

Jersey 0.00 0.00 0.00 0.00 0.00 0.00 

Madison 1.08 357.50 0.04 12.52 0.07 23.36 

Monroe 0.12 39.00 0.00 0.30 0.00 1.46 

St. Clair 2.14 865.33 0.17 78.89 0.22 107.05 

Metro-East NAA 3.34 1,261.83 0.21 91.71 0.29 131.87 

Attainment Area 19.14 6,520.96 0.82 326.15 1.18 432.10 

State Total 56.79 19,345.36 27.99 9,945.50 5.55 1,982.77 

5.2.2.2.2 Calculation of Aircraft Emissions 

Aircraft activity at an airport is normally expressed either as the number of aircraft 

operations (“ops”) or as the number of landing and takeoffs (LTOs). An aircraft 

operation is a movement of an aircraft under its own power at the airfield, i.e., a landing 

or takeoff (with any necessary taxiing) or a missed approach. An LTO is one landing 

and one takeoff. Thus the number of LTOs is, for all practical purposes, half the 

number of operations. 

112 
Emissions from an aircraft are the product of the source activity (ops or LTOs) and the 

emission factor which is normally expressed in pounds per LTO for that aircraft as 

shown in Equation 5.5. 

 E = OPS × EF / 4000 = LTO × EF / 2000 (5.5) 

 where: 

E = emissions 

 OPS = operations 

 EF = emission factor 

 LTO = landings and takeoff operation 

The total emissions at an airport is the sum of the emissions for all the aircraft types 

using the airport, each of which would have different operations and emission factors. 

5.2.2.2.3 Aircraft Engines and Modes 

There are two basic types of aircraft engines: 

• Turbine, turboprop or turbojet, engines which power virtually all military and 

commercial and many business aircraft. These use jet fuel, a kerosene blend of 

low volatility 

• Piston engines which power most small general aviation aircraft, private planes, 

and some business aircraft. These use a special high-octane aviation gasoline. 

Those engines operate chiefly in five modes: 

• Taxi/Idle: at very low power when idling or during taxiing before taking off or after 

landing 

• Takeoff: at full power during takeoff until the aircraft is about 500 feet above the 

ground 

• Climbout: at slightly reduced power during which the aircraft climbs to its cruising 

altitude 

• Cruise: at further reduced power level at cruise where the aircraft maintains a 

constant speed and altitude 

• Approach: at a moderate to low power level during descent and the approach to 

landing 

Emission factors for aircraft are usually expressed as mass of pollutant per LTO, and 

are derived from measurements made by engine manufacturers. The emission factor 

for a given aircraft is a function of the make and model of the aircraft and its engine(s), 

the number of engines on the aircraft, the fuel flow rate for each mode and the time the 

aircraft spends in each mode. 

113 
5.2.2.2.2 Airports in Illinois 

This inventory deals with aircraft emissions at Public Use Airports (PUAs) and military 

airfields in Illinois, particularly those in the Chicago and Metro-East ozone NAAs. PUAs 

are privately or publicly owned airfields that are registered with the state as being open 

to the flying public. Almost all the approximately 6,500 general aviation aircraft 

registered in Illinois are based at one or another of the approximately 115 PUAs located 

in 75 of the state’s 102 counties. There are 19 PUAs in the Chicago NAA and seven 

PUAs in the Metro-East NAA. Much data on PUAs, including the number and types of 

based aircraft and the number of operations per year, may be found in the annual IDOT 

publication Illinois Airport Inventory Report. Illinois EPA used the 2003 edition, which 

contains data through 2002, in the preparation of this inventory. Number of operations 

for each airport is included in Appendix G. 

Military airfields are owned by the government but are reserved for military operations. 

In general, they are not open for public use. There is presently one military airfield in 

Illinois, Scott Air Force Base near Belleville in the Metro-East NAA. The only other 

military airfield of importance in Illinois, Glenview Naval Air Station in the Chicago NAA, 

was closed in the early 1990s. In addition, US Air Force Reserve and the Illinois Air 

National Guard units based at the municipal airports in Springfield and Peoria fly F-16 

jet fighters and C-130E turboprop transports, respectively. Those aircraft have been 

taken into account in the emission calculations for those airports. Military aircraft 

occasionally land or practice instrument landings at civilian airfields other than where 

they are based. The total number of fixed-wing military aircraft based in Illinois is under 

100. Detailed information about operations at Scott AFB was obtained from the base’s 

environmental office. Scott AFB is presently (2002) home to an airlift wing flying C-9 

and C-21 transports and an air refueling wing flying KC-135 jet tankers. The refueling 

wing was formerly based at O’Hare Airport in Chicago and moved to Scott AFB in the 

autumn of 1999. 

According to IDOT’s Bureau of Aeronautics, there are many small private airstrips and 

restricted landing areas scattered around the state. Approximately four dozen are in the 

Chicago NAA and a dozen or so are in the Metro-East NAA. These airstrips are not 

PUAs in that they are not open to the flying public. Operations data are not, in general, 

available for these private airstrips, but few have more than a handful of operations a 

month involving small piston engine aircraft. Emissions from operations at these 

airstrips and restricted landing areas are negligible. Henceforward in this document, 

“airport” will mean “public use airport.” 

114 
The Federal Aviation Administration (FAA) recognizes four categories of aircraft 

operations, namely: 

• Air Carrier or Commercial operations: those for large aircraft capable of carrying 

more than 60 passengers or 18,000 pounds cargo, i.e., scheduled major airline 

operations 

• Air Taxi operations: those in smaller aircraft than air carrier, i.e., small-scale 

passenger operations 

• General Aviation: all other non-military aircraft operations including private, 

business and civilian government operations 

• Military: all operations by military aircraft 

The FAA collects and publishes statistics on these categories for many airports 

nationwide. Large commercial airports usually have detailed information on aircraft 

operations by various aircraft makes and models and sometimes even engine types. 

Some information of this sort for domestic commercial activity in Illinois appears in the 

annual FAA publication Airport Activity Statistics of Certificated Route Air Carriers 

(Airport Activity Statistics) for 2002. It is possible then, to estimate commercial and/or 

air taxi aircraft emissions from airports in considerable detail. 

Most other airports have less detailed operations information. Civilian airports with 

control towers have accurate counts of operations by category of traffic. These counts 

are published annually by the FAA. Counts by month and by category from 1989 

through 2002 are available on the internet at the website of the FAA Office of Aviation 

Policy & Planning (http://api.hq.afaa.gov/apo_home.htm). Illinois EPA downloaded the 

2002 FAA data for the 18 Illinois airports with towers. General aviation airports without 

towers or commercial service generally have only rough counts or estimates of annual 

aircraft operations, as published in the IAIR, but emissions at such airports are small in 

any case. 

5.2.2.2.3 Estimating Emissions from Aircraft Operations 

The method that Illinois EPA used to estimate emissions for O’Hare and Midway 

Airports is based on the procedures outlined in Procedures Volume IV, Section 5.1 in 

which Equation 5.5 is applied on a by-aircraft basis. The Chicago Department of 

Aviation (CDoA) owns and operates Midway and O’Hare Airports. The CDoA, through 

its consultant, Landrum & Brown (L&B), provided Illinois EPA with the number of 

operations at the two airports by aircraft make and model, representative of a summer 

weekday in 2002. The number of ops are often not whole numbers because they are 

not specific to one particular day, but represent more or less the total number of 

weekday operations in June, July and August of 2002, divided by the number of 

weekdays, 65, in those three months. The CDoA data were ideally suitable for the 

purpose of this inventory and were used without modification after quality assurance 

checks. Since O’Hare, and to a lesser extent Midway, have nearly constant traffic from 

month to month throughout the year as shown by FAA operations data, the CDoA 

115 
operations were compared to 1/31 of the August operations. CDoA’s number was 

slightly higher, but agreement was within a few percent. 

The CDoA/L&B data covered not only the domestic commercial traffic that appears in 

the FAA’s annual Airport Activity Statistics publication, but international commercial 

traffic, air taxi and other categories of air traffic as well. Based upon aircraft type 

information in the EDMS aircraft emission factor database, aircraft in CDoA’s list were 

assigned to one of the four categories of operations. Broadly speaking, jumbo, longand medium-range jets were classified as air carrier. Most turboprops where classified 

as air taxi. Business jets/turboprops and conventional aircraft were classified as 

general aviation and military aircraft were classified as military. This breakdown was in 

broad agreement with the numbers reported for O’Hare and Midway by the FAA. 

The emission factors for each aircraft type in pounds of pollutant (CO, HC, NOx) per 

LTO were calculated for each aircraft type in the CDoA/L&B list using information in the 

Environmental Data Management System (EDMS) database files. EDMS has 

succeeded the FAEED (FAA Aircraft Engine Emission Database) computer program as 

FAA’s standard model for environmental calculations. The EDMS databases contained 

information on: 

• The number of engines on each aircraft type 

• Normal times-in-mode (TIM), typically in minutes or fractions of an hour for the 

four operating modes for each aircraft type 

• The engine model or models used in each aircraft type 

• Modal emission factors in lb/LTO per unit time for each of the four modes for 

each engine model 

Aircraft engine emission factors do not vary significantly with ambient air temperature so 

they need not be adjusted for the seasons. 

A spreadsheet was used to calculate total emission factors for each pollutant per LTO 

for each aircraft type, according to Procedures Vol. IV, § 5.6. For each mode, the 

emission factor for each engine was multiplied by the corresponding TIM to obtain 

modal emissions per engine per LTO. These were summed to get total emissions per 

engine per LTO and that was multiplied by the number of engines on the aircraft to give 

total emissions per LTO for the aircraft. Following the methodology in § 5.6, the 

hydrocarbon emission factors were assumed to be for total hydrocarbons (THC) and 

correction factors to convert THC to VOM were applied to the emission calculations. 

The TCH/VOM correction factors used were as follows: 

• Commercial: 1.095 

• Air Taxi: 0.991 

• General Aviation: 0.970 

• Military: 1.105 

116 
Equation 5.6 is therefore used to compute VOM emissions for a given aircraft type. 

 EVOM = OPS × EFVOM × (T/V) / 4000 (5.6) 

 where: 

 EVOM = emissions of VOM 

 OPS = operations 

 EFVOM = VOM emission factor 

 T/V = ratio of THC to VOM conversion factor 

Modal emissions, the emissions that occur during each of the four engine-operating 

modes of interest, depend upon the amount of time the aircraft spends in that mode. 

Takeoff, climbout and approach times are fairly standard for various types or categories 

of aircraft, but the amount of time an aircraft spends taxiing and idling can vary greatly 

depending on congestion at the airport. Illinois EPA used EDMS’s standard (default) 

TIMs which differ from aircraft for the takeoff, climbout and approach modes, but 

replaced EDMS’s standard taxi/idle times by airport-specific taxi/idle times as reported 

by the FAA for Midway and O’Hare. Since taxi-idle times for O’Hare are different from 

those for Midway, emissions pr LTO are different for the same aircraft type at the two 

airports. 

In cases where no emission factor existed in the EDMS or elsewhere for a particular 

listed aircraft/engine combination, the factor was chosen from those of similar engine 

types in the same or similar airframes, in accordance with Volume IV’s 

recommendation. Information on common aircraft/engine combinations from EDMS 

airport emissions estimation program was helpful in this regard. 

Emissions for each aircraft/engine combination at O’Hare and Midway were calculated 

on a spreadsheet my multiplying the appropriate overall emission factor (the sum of the 

by-aircraft emission factors for the individual four modes) by the number of LTOs and 

converting to tons. The resulting emissions by aircraft type were then summed to get 

airport totals. Subtotals were also calculated for the commercial, air taxi, general 

aviation and military categories of operations. 

For airports other than O’Hare and Midway, the above method had to be modified. 

Where operations data by commercial aircraft type from Airport Activity Statistics were 

available, the above method could be used to estimate the emissions from those 

operations. However, this accounts for only part of the commercial or air taxi categories 

of aircraft operations defined by the FAA and does not account for the other categories 

at all. Airports with control towers keep records of operations in the four categories, 

though, and this information was used where available. There are 18 civilian airports 

with control towers in Illinois: 

117 
• Chicago 

o O’Hare (ORD) 

o Midway (MDW) 

o Chicago/Meigs (CGX) 

• Elsewhere in the Chicago NAA 

o Palwaukee (PWK) 

o Aurora (ARR) 

o Waukegan (UGN) 

o DuPage County (DPA) 

• Metro-East NAA 

o Alton (ALN) 

o Cahokia (CPS) 

• Downstate attainment counties 

o Rockford (RFD) 

o Moline (MLI) 

o Peoria (PIA) 

o Bloomington (BMI) 

o Champaign (CMI) 

o Springfield (SPI) 

o Decatur (DEC) 

o Carbondale (MDH) 

o Marion (MWA) 

As noted above, the Illinois EPA obtained 2002 operations from the FAA through the 

internet for each of these airports. The data consisted of the number of operations in 

each of the four categories for each month of 2002. Data were not available to 

distinguish between weekday and weekend operations, so typical summer day 

operations were calculated as 1/92 of the sum of the June, July and August operations. 

As a quality check, these FAA operations totals were compared to those from the Illinois 

Airport Inventory Report 2003 which are rounded. 

Airports other than those with towers listed above are assumed to have 100 percent 

general aviation traffic. The annual operations data for these small airports were taken 

from the IDOT publication Illinois Airport Inventory Report 2003. The most up-to-date 

operations estimates were used, and assumed to change little from year to year. 

Average daily operations were estimated by dividing the annual operations by 365 and 

these results were converted to summer weekday ops by multiplying by 1.15 because 

the general aviation aircraft in particular are flown more in summer than in winter. The 

factor 1.15 is based on a comparison of average summer day operations with average 

daily operations for Illinois airports with control towers, and is reasonably representative. 

For Scott AFB and the co-located MidAmerica Airport, operations data were obtained 

from Base Operations through the base’s Environmental Management office. 

Operations data for the three aircraft types stationed at Scott AFB (C-9, C-21 and KC135), and for the Boeing 727s operating from MidAmerica Airport were available. 

Aircraft specific emission factors were used to calculate emissions for those aircraft. 

118 
Other non-military aircraft operations at Scott AFB and MidAmerica were assumed to be 

general aviation or air taxi and appropriate fleetwide emission factors as described 

below were used to calculate those emissions. There are very few other commercial 

flights out of MidAmerica. 

Where operations data for individual aircraft types do not exist, Procedures Vol. IV 

allows the use of fleetwide emission factors. Fleetwide average emission factors for 

each of the four categories were published in the 1989 and 1992 editions of Volume IV 

(§ 5.2.4.2). They were used in Illinois EPA’s approved 1990 inventory and are shown 

below in Table 5-14. 

These fleetwide emission factors, especially those for the air carrier and military 

categories given in the 1989 Vol. IV, date from 10-15 years ago (or more) and may not 

be representative of today’s aircraft fleet. Therefore, on advice from USEPA/OTAQ, the 

1989 factors were compared with FAEED and EDMS emission factors for various 

aircraft types in the four categories. Reasonable, slightly conservative, average 

fleetwide factors were developed using engineering judgment, for each of the categories 

for downstate airports, where necessary. The emission factors used in the emission 

calculations are in Table 5-15. 

Table 5-15: Fleetwide Emission Factors (lb/LTO) 

Pollutant Commercial Air Taxi General 

Aviation 

Military 

CO 24.0 30.0 13.0 40.0 

HC 4.0 5.0 0.5 10.0 

NOx 24.0 2.0 0.1 10.0 

The revised fleetwide emission factors were developed from the old factors by taking 

into account a number of considerations. 

For commercial and air taxi aircraft, the old emission factors most likely assume a 

significant proportion of high-emitting jumbo jets as well as ordinary jetliners with old 

and higher emitting engines. Few such aircraft use downstate airports in Illinois. 

For general aviation aircraft, emissions from small airports are from quite small propeller 

aircraft. Few data exist on their emission factors, but what data exist were consulted 

and compared with the Procedures Vol. IV values. The emission factors appear to be 

satisfactory for this category. The values, however, have been rounded to take into 

account the somewhat greater emissions from business jets and from general aviation 

aircraft other than small private planes. 

For military aircraft, the old emission factors are rather high compared to those for most 

military aircraft whose EDMS emission factors are available. Large, high-emitting 

aircraft like B-52s and C-5s do not commonly use Illinois airports or military bases, so 

119 
the average emission factors should be fairly low. Emission factors from EDMS based 

upon aircraft commonly found in Illinois are shown in Table 5-16. Illinois EPA has 

assumed that at least 85 percent of the military operations at Springfield and Peoria 

were from the aircraft based there and that the other 15 percent of military operations at 

those and other airports had average fleet-wide emission factors. 

Scott AFB has considerable transient military traffic, according to its environmental 

management office, but detailed data on transient aircraft types were not available. 

Emissions from transient aircraft were therefore estimated using the fleetwide emission 

factors from Table 5-15. These emissions are conservative because the military 

emission factors in Table 5-15 are considerably higher than those for C-9s and C-21s, 

as can be seen in Table 5-16. 

Table 5-16: EDMS Emission Factors for Military Aircraft Based in Illinois (lb/LTO) 

Aircraft Based at CO HC NOx 

F-16 Springfield 37.1 9.7 11.2 

C-130E Peoria 19.6 17.5 11.5 

C-9A Scott AFB 6.7 1.5 10.2 

C-21A Scott AFB 5.9 1.7 1.9 

KC-135 O’Hare/Chicago 58.0 3.3 34.4 

The fleet hydrocarbon emission factors given in the tables above are assumed to be for 

THC. Therefore, the THC to VOM correction factors were applied when computing 

VOM emissions for airports other than O’Hare and Midway, and in the same manner as 

the O’Hare and Midway computations. All the emission calculations were done on a 

spreadsheet. 

5.2.2.2.4 Detailed Calculations of Aircraft Emissions 

Calculations were performed on spreadsheets in which operations data and emission 

factors were placed. In the O’Hare and Midway cases, the calculations were by aircraft 

type and summed by category. For other airports with towers, the calculations were 

made by category. For all other airports, the calculations were made assuming all 

aircraft were general aviation. Emissions from airports other than O’Hare, Midway and 

those with control towers are quite small. 

5.2.2.2.5 Emissions from Aircraft Auxiliary Power Units (APUs) 

APUs are small turbine engines installed in the hulls of many large and medium aircraft 

to generate electricity and compressed air to keep the aircraft’s systems operating when 

the main engines are off, as when the aircraft is parked at an airport gate. APUs use jet 

fuel and generate exhaust emissions like the main engines do. When in use, they run 

120 
at full throttle. Most aircraft in the commercial category have APUs, but comparatively 

few air taxi or general aviation aircraft have them. Some military aircraft, especially 

transports, have APUs. 

APU emissions for an aircraft are the product of its APU’s emission factor (pounds per 

hour of operation), the time in use in (hours per LTO) and the number of LTOs. 

Emissions from APUs are difficult to estimate accurately because good emission factor 

information is not available for many APU models and little information is available 

about APU time in use. 

Despite this, it has proved possible to make reasonable estimates of APU emissions at 

Midway and O’Hare Airports. Landrum & Brown, aviation consultants to the Chicago 

Department of Aviation, estimates the average APU time in use at Midway and O’Hare 

to be 26 minutes. L&B supplied Illinois EPA with a list of aircraft with APUs using those 

two airports in 2002. APU emission factors in pounds of pollutant per hour of operation 

were taken from the EDMS program, version 4.11. Illinois EPA combined that 

information with data on the number of operations by aircraft type for the two airports, 

also supplied by L&B, to obtain APU emissions. Those emissions are shown in Table 

5-17 below. Emission estimates for Midway and O’Hare airports include APU 

emissions. 

Emissions from APUs at Illinois airports other than Midway and O’Hare are negligible. 

For all practical purposes, APU emissions occur only at airports with commercial 

operations. Midway and O’Hare airports account for nearly 97 percent of the 

commercial operations in Illinois. Of the 16 remaining airports with towers in Illinois, 

only Bloomington, Moline, Peoria and Rockford had more than a handful of commercial 

operations in 2002. Taken together, these four airports account for about 1/30th the 

number of commercial operations. Therefore, together they would have at most 1/30th

the APU emissions that Midway and O’Hare do. Other Illinois airports, those small ones 

without towers or commercial operations, have essentially no APU emissions. 

Table 5-17: Emissions from APUs 

Airport CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Midway 0.14 45.88 0.09 28.95 0.00 0.07 

O’Hare 0.59 210.43 0.37 131.77 0.04 14.50 

5.2.2.2.6 Annual Aircraft Emissions 

Annual emissions at O’Hare are assumed to be 354 times summer weekday emissions 

and emissions at Midway are assumed to be 330 times summer weekday emissions. 

These factors, supplied by Landrum & Brown, are based on the ratio of summer 

weekday LTOs to annual LTOs. Aircraft activity at O’Hare varied little from month to 

month in 2002 but there are slightly more LTOs in summer than winter. Midway’s 

121 
aircraft activity varies. There were quite a few more LTOs in the summer 2002 than in 

winter. 

For the other 16 airports with towers in Illinois, operations data is available by month, so 

total annual operations, and therefore, total annual emissions, are easy to compute. 

For all other airports, the Illinois Airport Inventory Report 2003 gives the number of 

annual operations which allowed annual emissions to be calculated. 

5.2.2.3 Commercial Marine Vessels 

This category includes large cargo ships, passenger ships, oil tankers, etc., powered by 

steam or internal combustion engines and used for commercial purposes such as 

transport of passengers, cargo movement, commercial fishing and the like. Tugboats 

and pushboats, both used in harbors and used to propel barges on rivers are included 

in this category. Emissions for pleasure boats are not included in this category, but 

rather in the other non-road engines and vehicles category describe in § 5.2.2.4 below. 

Two main types of Commercial Marine Vessels found in Illinois waters are: 

• Lake vessels 

• River vessels 

Lake vessels are typically large boats and ships that operate on the Great Lakes. 

Almost all are diesel powered. Many use residual fuel rather than the distillate fuel used 

by most other commercial vessels use. Since only Cook and Lake Counties have 

shorelines and harbors on Lake Michigan, emissions from lake vessels occur only in 

those two counties. Lake vessels may be in an Illinois port for several days during 

loading and unloading, but once they leave the harbor, they quickly move out of Illinois 

waters. 

River vessels are smaller, shallower-draft boats that travel the public waterways of the 

Illinois, Mississippi and Ohio Rivers. The Wabash and Kaskaskia Rivers are navigable 

for a small part of their length, but commercial traffic on them is negligible. Most river 

vessels are diesel-powered boats or tugs that push or pull large rafts of barges up and 

down the rivers. They may stay in state waters for days at a time. They use distillate 

fuel. 

Lake and river vessels overlap in the Chicago area. It is assumed that all CMVs in 

Illinois are diesel powered. There are a few steam vessels plying Illinois waters. 

Emission factors for steam vessels are similar to those for diesel vessels, so little error 

is introduced by this assumption. 

There are two types of CMV emissions, dockside and underway. Dockside emissions 

are those that take place when the vessel is in port. Like large aircraft, large boats and 

ships require power to run electrical, ventilating and other equipment even when they 

122 
are tied up to a dock. Smaller vessels in port often get the power they need from 

dockside connections, but larger ships (i.e., those with drafts greater than 18 feet) 

usually use their own engines, or a small auxiliary engine, at low throttle when in port to 

generate their own power. USEPA guidance is to assume each large ship is in port for 

three days. In Illinois waters, only lake vessels have such deep drafts, so dockside 

emissions are calculated only for those. Underway emissions are those that take place 

while the vessel is under way, that is, in transit. 

The emissions for this category were estimated for Illinois EPA by Environ Corp, under 

a contract with LADCO to make estimates for this category for all the LADCO member 

states. The estimates were specific for 2002. The emissions were based on fuel use, 

apportioned by county based on commercial traffic on the rivers or in the Lake. Environ 

used data from the Army Corps of Engineers and US Department of Energy to make its 

calculations. 

Since information on waterborne traffic is not readily available by month, Environ 

calculated emissions on an annual basis and converted to tons per summer day by 

dividing by 204.75. This is equivalent to saying waterborne commerce takes place 

mostly in spring, summer and early autumn, with much less traffic in winter. This is 

reasonable. According to Corps of Engineers information collected over the last 35 

years or so, waterborne traffic on the Mississippi south of Quincy, Illinois continues 

throughout the year, only occasionally being stopped for a few days by ice or water 

levels. North of Quincy ice blockages are more common. In most years, there is little 

traffic on the river upstream of the Quad Cities from mid-December through mid-March. 

Barge traffic on the Illinois River is usually little affected by ice buildup, though, as with 

the Mississippi, there is less waterborne traffic in the winter. 

Once emissions were calculated for a waterway, the emissions are assigned to counties 

based upon the miles of river shoreline in the county. In Environ’s calculations, half the 

emissions on the upper Mississippi River go to the states on the west bank and half to 

the states on the east bank. This is also the case for the Ohio River (north/south). The 

emissions along stretches of the Mississippi are attributed to the counties in a state 

based on the county’s river miles as a fraction of the length of the stretch for which the 

emissions were calculated. Environ apportioned the emissions along the Illinois River 

to the counties on the south and east bank. 

Emissions from ferries and other work boats (fishing boats, dredges, etc.) on the Illinois 

waterways are included in the emission totals from Environ. Data on their operations 

are more difficult to obtain and their emissions are small, though not quite negligible. 

123 
Table 5-18: Commercial Marine Vessel Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 1.32 270.67 7.49 1,533.99 0.18 35.98 

DuPage 0.21 42.29 1.07 219.89 0.02 4.81 

Grundy Twps 0.18 36.99 0.97 199.42 0.02 4.57 

Kane 0.00 0.00 0.00 0.00 0.00 0.00 

Kendall Twps 0.00 0.00 0.00 0.00 0.00 0.00 

Lake 0.00 0.00 0.00 0.00 0.00 0.00 

McHenry 0.00 0.00 0.00 0.00 0.00 0.00 

Will 0.14 29.32 0.77 158.07 0.02 3.62 

Chicago NAA 1.85 379.27 10.31 2,111.37 0.24 48.99 

Jersey 0.53 109.06 2.87 588.00 0.07 13.48 

Madison 1.75 359.10 9.20 1,882.92 0.20 41.65 

Monroe 0.62 127.43 3.36 687.01 0.08 15.75 

St. Clair 0.25 50.97 1.34 274.80 0.03 6.30 

Metro-East NAA 3.16 646.56 16.77 3,432.73 0.38 77.17 

Attainment Area 12.07 2,470.40 64.99 13,310.28 1.49 304.94 

State Total 17.08 3,496.23 92.07 18,854.38 2.10 431.10 

5.2.2.4 Other Non-road Engines and Vehicles 

This category includes all other portable motorized equipment, from lawnmowers to 

snowblowers, and farm tractors to earthmoving equipment. Engines are powered by 

spark-ignition (usually fueled by gasoline) and some by compression ignition (diesels). 

There are two types of spark-ignition engines: 2-stroke and 4-stroke. The three types 

of engines, 2-stroke, 4-stroke and diesel, have very different emission characteristics 

so, they are treated separately in the inventory. Some non-road emission sources use 

CNG or LPG as a fuel. 

Most small to medium-sized non-road equipment, from lawnmowers to portable 

generators are powered by 4-stroke gasoline engines. Two-stroke engines are used 

chiefly in fairly small applications (e.g., snowblowers, hand-held equipment) because 

they are smaller and lighter than 4-stroke engines of the same power output. Diesel 

non-road equipment tends to be large (e.g., tractors, construction equipment). 

For this inventory, Illinois EPA used the NONROAD model (version 2.2.0a – June 2003) 

to estimate non-road emissions by county. The NONROAD model estimates emissions 

of hydrocarbons, CO, NOx, SOx and PM (both PM10 and PM2.5) from all non-road 

categories except aircraft operations, locomotives and commercial marine vessels. The 

model takes into account growth, fuel characteristics and control programs. The inputs 

used in the NONROAD model when estimating summer weekday emissions are shown 

in Table 5-19. 

124 
Table 5-19: NONROAD Input Parameters for Summer Daily Emissions 

NONROAD Input 

Parameter 

Chicago 

NAA 

Downstate 

North 

Downstate 

South 

MetroEast NAA 

Fuel RVP (psi) 6.7 8.1 8.1 6.9 

Oxygen % 3.5 3.5 3.5 3.5 

Gasoline sulfur 

content (ppm) 

247 102 102 183 

Diesel sulfur 

content (ppm) 

375 375 375 375 

CNG/LPG sulfur 

content (ppm) 

0 0 0 0 

Minimum 

temperature (F) 

64 64 71 71 

Maximum 

temperature (F) 

84 84 89 89 

Average 

temperature (F) 

74 74 80 80 

Stage II control 

(%) 

0 0 0 0 

Summer daily emission totals were obtained by running the NONROAD model for the 

Chicago, Downstate North, Downstate South and Metro-East areas with appropriate 

inputs from Table 5-19. The output file from the NONROAD model were imported into a 

spreadsheet. The spreadsheet’s pivot table function was used to generate a table of 

emissions by county (across) and category and engine type (down) for 2-stroke, 4-

stroke and diesel engines. 

Annual emissions were calculated in essentially the same manner. The annual totals 

for the four areas of the state were obtained by running the NONROAD model four 

times for each area, using the seasonal inputs shown in table 5-20. 

125 
Table 5-20: NONROAD Input Parameters for Annual Emissions 

NONROAD Input 

Parameter 

Season Chicago 

NAA 

Downstate 

North 

Downstate 

South 

MetroEast NAA 

Fuel RVP (psi) Winter 

Spring 

Summer 

Fall 

14.0 

9.5 

6.7 

8.1 

13.0 

10.3 

8.1 

9.4 

13.0 

10.3 

8.1 

9.4 

13.4 

9.4 

6.9 

8.2 

Gasoline sulfur 

content (ppm) 

Winter 

Spring 

Summer 

Fall 

247 

247 

247 

247 

249 

235 

102 

169 

249 

235 

102 

169 

236 

203 

183 

193 

Diesel sulfur 

content (ppm) 

All 

seasons 

375 375 375 375 

Minimum 

temperature (F) 

Winter 

Spring 

Summer 

Fall 

26 

36 

64 

43 

26 

36 

64 

43 

30 

45 

71 

49 

30 

45 

71 

49 

Maximum 

temperature (F) 

Winter 

Spring 

Summer 

Fall 

40 

56 

83 

61 

40 

56 

83 

61 

48 

65 

89 

67 

48 

65 

89 

67 

The seasonal outputs for each area were imported into a spreadsheet and summed to 

another page to obtain the annual total. The pivot table function was then used to 

obtain the emissions summed by county and source category as above. The resulting 

emissions for daily and annual emissions are summarized in Table 5-21. 

Table 5-21: Off-road Engine Emissions 

County CO 

(tpd) 

CO 

(tpy) 

NOx 

(tpd) 

NOx 

(tpy) 

VOM 

(tpd) 

VOM 

(tpy) 

Cook 1,253.00 291,234.18 112.41 25,308.73 107.81 24,456.86 

DuPage 412.27 93,031.46 30.83 6,864.01 27.14 6,522.46 

Grundy Twps 2.24 739.60 0.21 85.38 0.39 110.22 

Kane 137.16 30,706.12 16.23 3,420.88 9.43 2,254.67 

Kendall Twps 6.94 2,659.27 0.29 119.43 0.46 326.09 

Lake 470.74 95,204.32 25.03 5,323.30 59.91 11,997.51 

McHenry 107.46 23,225.60 8.37 1,774.99 7.51 1,769.23 

Will 169.53 35,886.64 13.36 2,737.97 13.19 3,041.99 

Chicago NAA 2,559.35 572,687.19 206.75 45,634.69 225.83 50,479.03 

Jersey 5.02 1,151.10 1.56 277.65 0.65 155.37 

Madison 70.79 13,631.72 7.52 1,574.24 5.61 1,368.55 

Monroe 6.89 1,490.68 1.68 311.05 0.65 155.37 

St. Clair 59.39 11,125.63 5.80 1,179.56 4.33 1,040.98 

Metro-East NAA 142.08 27,399.13 16.57 3,342.50 11.24 2,720.27 

Attainment Area 1,148.46 253,028.70 291.56 55,247.50 109.09 33,683.35 

State Total 3,849.90 853,115.02 514.87 104,224.69 346.15 86,882.65 

126 
6 Quality Assurance 

6.1 Purpose of the Inventory 

The objective of this emission inventory is to present an accurate and comprehensive 

account of all ozone precursor emissions from point, area and mobile sources for the 

entire State of Illinois in accordance with the requirements of the CAA. This inventory is 

a base year emission inventory for the year 2002, which will be used as a basis to 

assess Illinois’ progress towards meeting the State’s Rate of Progress Plan 

requirements. The ozone precursors included in the inventory are CO, NOx and VOM. 

Emissions presented in the 2002 periodic emission inventory are typical summer day 

and annual. 

6.2 Scope of the Quality Assurance Plan 

The Illinois EPA has implemented quality assurance (QA) procedures and quality 

control (QC) checks at various stages in the inventory process. The QA preparations 

involved in the development of the emission inventory were based on the procedures as 

outlined in the USEPA’s publications EPA-450-4-88-023, Guidance for the Preparation 

of Quality Assurance Plans for O3/CO SIP Emission Inventories and EPA-450/4-91-

022, Quality Review Guidelines for 1990 Base Year Emission Inventories and Illinois 

EPA’s document, Illinois Environmental Protection Agency Point Source Emissions 

Inventory Quality Assurance/Quality Control (QA/QC) Plan by the Radian Corporation 

(November 1991). Details of the QA program are discussed in the following sections. 

6.3 Summary of QA Activities 

In general, four basic stages were involved in the preparation of the 2002 emission 

inventory: planning, data collection, data analysis and data reporting. Data analyses 

include estimation of emissions for point sources that failed to report ozone season 

emissions in their annual emission report to the Illinois EPA. The reporting stage 

includes the presentation of summer ozone season data and emission estimates as a 

finished product in the required format. As a first step, the QA program was conceived 

earlier in the process and was implemented throughout the various stages of inventory 

development. Second, the collection of data (or representative samples of it) had 

undergone review for suitability, completeness and correctness. Next, all the 

methodologies used in the calculation of missing or unreported emission data and those 

methodologies used for various data analyses were all reviewed to ensure the inventory 

of such emission data were appropriate representations of each respective emission 

category. Lastly, the finished periodic emission inventory product was checked and 

audited for completeness and accuracy. 

127 
6.3.1 Inventory and QA Planning 

Illinois EPA’s Air Quality Planning Section inventory staff used a QA plan largely based 

on requirements according to the CAA and USEPA quality assurance and quality 

control guidance documents. Also, the overall inventory QA plan was influenced by 

experiences gained in the development of the approved 1990 based year ozone 

precursors emission inventories for both the Chicago and the Metro-East areas, as well 

as in the development of all previous inventories. 

6.3.2 Resource Allocation for QA 

In-house quality assurance activities required a person with experience and authority to 

carry out QA duties. The QA coordinator (QAC) interacted directly with the inventory 

staff or specialists for point, area and mobile sources. Essentially, the planning and 

implementation of QA checks are in accordance with the QA plan as described herein 

and with USEPA’s QA and QC guidance documents. 

Late in 1999, a major change in how the point source inventory is developed occurred. 

Until then, there was no person or group responsible for the data contained in the 

inventory. QA activities were performed as periodic inventories were needed. Due to 

this, the responsibility of compiling the point source emission inventory was moved from 

the Permit Section to the Inventory and Data Support Unit of the Air Quality Planning 

Section. 

6.3.3 Schedule and Project Planning 

The Air Quality Planning Section’s inventory staff’s experience in the development of 

the 1990 base year and subsequent inventories were drawn upon in preparing the QA 

plan for the 2002 periodic emission inventory. 

To prepare the 2002 AER data for inventory use, inventory staff reviewed the emission 

data prior to entering it into CAERS. The experiences in such review were also 

included as bases in developing the QA plan for this inventory. Many data range 

checks are built into the CAERS and ISSIS systems. This ensures values entered into 

the database are within acceptable levels such as those ranges of values for 

parameters indicated in Section 6.4. Knowledge that such input value ranges are 

automatically validated contributed to the overall design of the QA plan. 

As permits are issued, the emission data contained in the permit and application are 

compiled into the point source emission inventory by the inventory staff. Each source 

that has been coded is then reviewed for correctness and completeness by the Unit 

Manager. This review also contributes to the contribution of the overall design of the 

QA plan. 

128 
A review of the results of the 2002 AER input data and Illinois EPA entered data 

became the groundwork for planning and scheduling the QA efforts for the 2002 

inventory. Specific key parameters identified in the inventory were tagged as a potential 

focus for QA work and incorporated in the planning for reviewing the point source 

emissions data. 

The inventory staff charged with the mobile and area source portions of the inventory 

began their parallel QA efforts to enable a timely completion of the inventory, all QA 

checks and audits. For on-road mobile sources, review of emission factors was 

primarily confined to QA of the inputs to the MOBILE model. For non-road sources 

other than aircraft, the QA procedures were comparable to those used in the 1999 and 

2002 (periodic) inventories. The non-road source methodology and emission data were 

compared with previous studies done on this category. For aircraft, QA consisted 

mainly of checking the activity data against those from previous years and checking 

emission factor data versus similar data published by USEPA. 

6.4 QA Technical Information 

As noted above, the emission inventory system the DAPC uses contributes to the 

overall quality assurance aspect for this inventory. The emission inventory data has 

already been range checked for the following parameters: 

• Stack height ≤ 1250 feet 

• Stack diameter ≤ 99.99 feet 

• Hours per year ≤ 8760 

• Peak ozone season hours ≤ 2190 

• Weeks per year ≤ 52 

• Peak ozone season weeks ≤ 13 

• Days per week ≤ 7 

• Hours per day ≤ 24 

• Seasonal throughput totals = 100 percent 

In addition to the validation of input data ranges, ISSIS and CAERS also perform 

automated validation of codes such as SIC and SCC. With such tasks performed, the 

inventory staff is more focused on reviewing key parameters and other aspects of the 

inventory that may significantly affect the accurate representation of typical summer 

weekday emissions. 

6.4.1 Prioritizing Sources and Data Elements 

The data elements of the 2002 periodic emission inventory were based on the source 

reported emissions for 2002. This reported data was deemed more representative 

compared to the emissions from growing a previous point source inventory. An analysis 

was performed by comparing the emission level in 1999 and 2002 on a point-by-point 

129 
basis. With tens of thousands of records statewide to QA for purposes of this inventory, 

this methodology helped to focus resources towards emission points that were found to 

have a significant increase or decrease in emissions from 1999 to 2002. If the 2002 

emissions differed from the 2002 emission by ±10 percent or more, further analysis was 

performed and the submitted annual emission report was scrutinized. In many cases it 

was also necessary to review past changes to the inventory contained in ISSIS to 

identify the changes in emissions were due to more accurate coding of the inventory. A 

closer review on reported values for CO, NOx and VOM was done to ascertain the 

accuracy of entered values in the preliminary 2002 data retrieved from the database. 

Sources having the largest increase or decrease in emissions levels between 1999 and 

2002 were identified and all emission points within the source were scrutinized for 

appropriate inventory use. 

6.4.2 Data Sources and Checking Procedures 

Although the data used in the point source emission inventory came directly from the 

sources themselves, some data were deemed incorrectly represented and corrected 

accordingly. If necessary, all possible sources of information were used in this QA 

effort, including AERs from previous years, to determine reliability of the data for 

inclusion in the inventory. The inventory staff assessed all data that were presented 

and took into account the capabilities and biases of the organization supplying the data, 

the techniques used to collect the data and the purpose for which the data had been 

compiled. All of these provided an overall understanding of the limitations of reported 

data and served as a guide in choosing the best data for use in the inventory. 

All reported data from the source’s 2002 AER were checked at intervals and entered 

into CAERS. The point source reported data were reviewed and, in general, found 

acceptable as most companies have provided the necessary information required by 

Illinois EPA. Area source data, such as census and meteorological information, sales of 

taxable substances like motor fuels, landings and takeoffs at airports, etc. came from 

federal or state government sources and are relatively accurate and found to be 

appropriate for use in this inventory. VMT data for mobile sources are published by 

IDOT and are reasonably accurate as well. Data from high-quality sources are still 

subjected to QA checks for relevance and suitability for the inventory. Other data for 

area sources may be several years old or were obtained in aggregate form (i.e., 

nationwide or statewide rather than by county or city) and are subject to further scrutiny. 

These sets of data underwent the same checks as the higher quality data and were 

reviewed with greater attention to bias and collection techniques. 

Review of the emission data was generally performed several times in the inventory 

development process. The inventory staff reviews the data as presented by each 

source to Illinois EPA. The QA Coordinator, through comparative analysis and other 

database review/manipulations sorts and flags suspect emission points and values and 

returns them to the responsible inventory staff for another round of QA review and 

scrutiny. Finally, after the consolidated emission results are being finalized, the 

130 
inventory staff performs a final review of emission values for inclusion in the inventory. 

The second independent QA check is more formal than the other two and is usually 

done on a sample of the data. The first and third checks cover all data used. 

6.5 Data Collection and Analysis 

The following sections describe Illinois EPA’s plans in collecting and analyzing emission 

data and the QA procedures used by the inventory staff in evaluating them. 

6.5.1 Identification of Emission Sources 

The Illinois EPA used a checklist similar to those in Appendix A of the QA guidance to 

make sure all appropriate source categories are covered in the inventory. In regard to 

point sources, all those sources that (a) are located in the State of Illinois and (b) are 

shown to have emissions of CO, NOx or VOM are automatically included in the 

inventory. Illinois EPA is confident all significant point sources are included in ISSIS. 

Nevertheless, as part of its QA efforts, Illinois EPA crosschecked the emission database 

generated for the 2002 inventory with previous inventories. 

The Illinois EPA also identified sources that were known to have operated in 2002 but 

which did not have their emission data entered into the system until 2003. Data 

reported at the source level plus data entered from the permit application in 2003 were 

combined to create a complete 2002 inventory for each of those sources. 

The 1999 periodic emission inventory was used as a comparison for all point emission 

categories in the 2002 inventory. The 2002 area source categories were also checked 

against the 1999 inventory. All area source and mobile source categories listed in the 

federal guidance are included in the inventory. Illinois EPA checks MOBILE model 

inputs (particularly temperatures and volatility) and VMT data for completeness, n order 

to ensure their suitable use in the model. For example, published gasoline volatility 

data was compared with those reported by the IDOA, which normally performs various 

tests on gasoline in the state. 

For area sources, the preliminary 2002 inventory developed by USEPA was used to 

identify additional source categories that may have not been calculated in previous 

years. There were very few categories that were not already inventoried (e.g., 

commercial cooking), but since annual emissions needed to be included activities that 

don’t take place during the summer (e.g., residential wood combustion) were also 

included in the inventory. 

131 
6.5.2 Data Quality 

To ensure the emission inventory is of the highest quality, QA procedures were in place 

for evaluating the quality and reliability of data for use in the inventory. These 

evaluation processes enable the inventory staff to make informed choices between 

sources of information, especially if the data from one source differs significantly in 

comparison with those that were obtained from another source. Also, the evaluation 

process allows the inventory staff and users of the inventory to make informed 

judgments about the validity of the emissions in any particular category. 

Representative QA actions include checking the base year relevancy of the data; the 

use of 2002 data where possible, is emphasized. However, if such base year data are 

unavailable, the most recent reliable data is used and noted accordingly in the inventory 

documentation. If certain data were updated to 2002 levels, the update method is noted 

and included in the documentation. 

Data were crosschecked with similarly published data. Appropriate caution was taken 

in the choice of “other published data”, especially when such data may have originated 

from the same source that produced the original data. In such cases, the actual data is 

not easily verifiable, but some credibility and support is given for such data, especially 

when an independent organization had chosen to publish such data. Checking 2002 

inventory data against those reflected in the past year or years is useful since 

magnitudes and trends may be verified in this manner. This is especially applicable for 

such data as VMT by road type. 

Some QA actions were more subjective, i.e., the judgment and experience of the 

inventory staff is important in these evaluations. The professional capabilities and 

biases, if any, of the suppliers of the data were taken into consideration, including the 

purpose for which the data were collected. Data organized by government agencies for 

taxation purposes (e.g., gasoline sales) and industry information on purchases and 

sales of materials and products (e.g., coal usage at the power plant), were considered 

of acceptable quality since both entities have a specific incentive to obtain the most 

accurate information. Data collection techniques, if known, were assessed accordingly. 

For example, information from plant inspections was considered more reliable than data 

from mail surveys. However, unless the inventory staff or the QA Coordinator had any 

significant comment about one or more of these subjective assessments (for example, 

when one source of data for a category was chosen over another), such assessments, 

as a rule, are not part of the inventory documentation. 

132 
6.5.3 Emission Estimation Methods 

Illinois EPA estimates emissions following the procedures outlined in these USEPA 

publications: 

• EPA-450/4-88-019, Inventory Requirements for Post-1987 Ozone State 

Implementation Plans, December 1988 

• EPA-450/88-021, Procedures for the Preparation of Emission Inventories for 

Precursors of Ozone: Volume I, Third Edition, December 1999 

• EPA-450/4-81-026d (Revised), Procedures for the Preparation of Emission 

Inventories for Precursors of Ozone: Volume IV: Mobile Sources, July 1989 

• AP-42, Compilation of Air Pollutant Emission Factors, Fifth Edition, January 

1995 and supplements 

Where specific USEPA guidance was not available, Illinois EPA used generally 

accepted engineering principles, calculations and judgment, supplemented by technical 

information from other sources, in estimating emissions. In all such cases, the method, 

data and other relevant information were identified accordingly. 

The emission estimates were adjusted to reflect conditions on a typical 2002 summer 

weekday as follows: 

• Point Sources: Emissions were calculated using peak ozone season 

emission rates from source submitted 2002 AERs. 

• Area Sources: Emissions were calculated using seasonal adjustment factors 

such as those reflected in USEPA guidance and by adjustments for 

representative 2002 summertime temperatures and volatility for certain 

categories (e.g., storage of gasoline and other VOM). 

• Mobile Sources: by adjusting VMT for 2002 summertime conditions and using 

representative 2002 summertime temperatures and fuel volatility when 

calculating the MOBILE model’s emission rates. The MOBILE6 model used 

in the CAA inventories calculates midyear (summer) emission rates directly 

so no adjustments were made to the emission rates on that account. 

6.5.4 Consistency with Other States 

Several conference calls were held early in the inventory development process with the 

states of Indiana, Michigan, Minnesota, Ohio and Wisconsin through LADCO to identify 

the emission factors or calculations methods to be used in calculating emissions from 

certain area source categories. 

133 
6.5.5 Calculations and Data Handling 

Computers were employed in all calculations for the inventory. Arithmetic errors are 

minimized in these calculations. Typographical errors and incomplete algorithms are of 

concern. For this situation, sample manual calculations were done for comparative 

purposes. At least one such calculation was made for every category. 

Computerized information was stored on the BOA’s network and was backed up nightly. 

Original inventory data continued to be maintained in the database. This data was 

extracted from the database and was maintained in an Access® database on the 

network. The Access® database was manipulated to obtain the 2002 point source 

inventory. 

6.5.6 Validation Procedures 

Data validation included a review for completeness of periodic emission inventory 

coverage. Illinois EPA believes all point sources in the state were accounted for in the 

inventory. In order to ensure completeness of coverage, Illinois EPA compared the lists 

of sources between the 1999 and 2002 inventories. 

Point and area sources were also checked against the list of categories shown in the 

QA Guidance to ensure all emission categories were covered. 

1. Data consistency: The input and output data are consistent with USEPA 

guidance documents as to the (1) area of coverage, (2) pollutants, (3) 

methodologies and (4) units of measurement employed. 

2. Area covered: This inventory was compiled on a statewide basis. 

3. Pollutants covered: CO, NOx and VOM, all ozone precursors, were inventoried 

in accordance with USEPA guidance requirements. 

The potential for “double counting” emissions in the area source inventory was 

also taken into consideration. This could occur in categories which have both 

point and area source emissions represented in the inventory (e.g., the dry 

cleaning category). The category’s point source emissions are assumed to be 

included in the total or gross emissions, which are generally estimated based on 

a surrogate factor such as population. The net area source emissions are then 

calculated by subtracting the calculated point source emissions from the total in 

order to avoid accounting for point source emissions twice. Some other area 

source categories which have the potential for double counting of emission are 

Graphic Arts, Commercial/Institutional fuel use and Waste Disposal. These were 

reviewed to make sure no double counting occurred in the inventory. 

4. Methods and units used: This procedure ensures the methods of calculations 

employed are consistent with USEPA guidance and usage of such units is 

correct. 

134 
6.6 Data Handling 

6.6.1 Data Coding and Recording 

Coding and recording of data into the ISSIS and CAERS database is done by trained 

inventory staff and is subject to standard operating procedures (SOPs). Similarly, 

updates and corrections discovered in the course of QA efforts were updated by the 

inventory staff. Any changes to the database are monitored and reviewed by the 

Inventory and Data Support Unit Manager. QA of information was further carried out by 

the QA Coordinator before any inclusions were considered into the 2002 inventory. 

6.6.2 Data Tracking 

Illinois EPA keeps its data and calculations mainly on personal computers and/or the 

BOA’s network. Raw data, especially for area sources, are obtained in various forms 

which are kept in files by the inventory staff for future reference purposes. Such files 

may include other information (e.g., sample calculations, estimates, sources of 

information, various relevant notes and correspondence, etc.) also for reference 

purposes. Any data in electronic form was backed up so that every file is available for 

quick recovery and reconstruction of data. 

6.6.3 Correcting Data 

When an inventory staff member discovers an error in reported data, that data is 

corrected in both the extracted data for the inventory and the originating data source. 

First, the person identifying the error consults with the Inventory and Data Support Unit 

Manager to determine whether a correction is truly necessary. If a correction is 

warranted, the person responsible for maintaining the extracted data is notified on what 

changes to make to that data set. Updates to the originating data set are performed by 

the inventory staff designated by the IDS Unit Manager. 

6.6.4 Missing Data 

This applies mainly to point source data. As noted above, missing emission data was 

not a major problem for Illinois EPA, but point source data have been known to be 

missing or in error for many small sources, and their absence, while not affecting 

emission totals, could be significant. For point sources, permit data has been used to 

obtain estimated values for missing data. In other categories, missing data, if they 

occur, were treated as data needing correction and dealt with accordingly. Where any 

missing data could not be obtained, a note was made of the fact, and suitable values 

estimated. The methods used to estimate the data is documented in detailed records. 

135 
6.7 QA Audits 

6.7.1 Internal 

The Illinois EPA did not perform a complete internal or agency QA audit during its work 

on the 2002 inventory. For example, the documentation for an area source category 

included: 

• The raw data (including emission factors) and references 

• The calculation method and references 

• The calculated emissions 

• Other comments for the category 

If the rationale for the choice of one particular data set or methodology over another 

was an issue, such an issue is discussed. Comments about the reliability or quality of 

the data (and hence the emission estimate) are also documented. In this sense the 

inventory documentation is its own audit. 

A review of the initial data in the point source inventory was compared against the 

annual totals reported on the source’s AER. Sources where the difference was greater 

than 10 tons were reviewed and updated as necessary. 

A further review of the point source inventory included looking at annual totals reported 

in 2001, 2002 and 2003 to check for appropriateness of using 2002 data. The initial 

review of this data revealed sources that, for various reasons, were not included in the 

2002 inventory (i.e., they had reported emissions for 2001 and 2003 but not 2002). 

These sources and emissions were added to the point source inventory. A second level 

review revealed ten sources that appeared to have emissions for 2002 that were not 

representative. In most cases, these sources were involved in ownership changes or 

were in the process of curtailing or shutting down some or all of their processes. Table 

6-1 identifies the sources that were individually reviewed and the decision made as to 

which year of emissions to use. 

136 
Table 6-1: Potential Sources with 2002 Emissions not being Representative 

Id Number Source City Inventory 

Year Used 

031258AAI Acme Steel Co Riverdale 2002 

031258ABR ISG Riverdale Riverdale 2001* 

031600AMC LTV Steel Co Chicago 2001 

031824AAB Premcor Refining Group Alsip 2002 

103806AAC Dixon-Marquette Cement Dixon 2002 

107035AAM Lincoln Developmental Center Lincoln 2002 

115015AAK Caterpillar, Inc Decatur 2001 

119010AAE Laclede Steel Co Alton 2001 

191803AAA Trunkline Gas Co Johnsonville 2002 

195818AAI Sterling Steel Company LLC Sterling 2001 

* Acme Steel sold part of its source to ISG Riverdale. At the time of the 2002 inventory 

this was not finalized and all the affected emission units were in the inventory for Acme 

Steel (031258AAI). Acme Steel’s 2001 AER included the equipment to be sold to ISG 

Riverdale so the emission inventory for ISG Riverdale was updated under the Acme 

Steel inventory. The 2005 inventory will have the equipment under the correct sources. 

6.7.2 External 

The Illinois Environmental Regulatory Group (IERG) requested source emission total 

data from Illinois EPA. This data was provided to IERG and was reviewed by its 

members. From this review, the Illinois EPA received comments and corrections to the 

point source inventory. These corrections were reviewed, and in most cases, accepted. 

The discrepancies identified arose primarily from the sources reporting data on nonstandard annual emission reporting forms which made it difficult for the data entry 

people to enter the data or be able to identify which emission units to associate the data 

with. The most common reason for not updating the inventory was that the inventory 

that was created by Illinois EPA agreed with the data that existed in the Acid Rain 

database. Table 6-2 identified the sources that responded and whether updates were 

made to their source. 

137 
Table 6-2: Sources Making Comments on Data Sent to IERG 

Id Number Source City Inventory 

Updated? 

003005AAI Bunge North America, Inc Cairo Yes 

007005AAF Chrysler Corp Belvidere Yes 

007804AAK Natural Gas Pipeline of America Belvidere Yes 

021814AAB Kincaid Generation, LLC Kincaid No 

031012AAO Nalco Chemical Co Bedford Park Yes 

031012ABI Corn Products International Bedford Park Yes 

031438ABL Elgin Energy Center Elgin No 

031600AIN Midwest Generation Chicago No 

043804AAA Midwest Generation Lombard No 

051808AAB Natural Gas Pipeline Co St. Elmo Yes 

057801AAA AES Duck Creek Canton Yes 

063806AAF Midwest Generation Morris No 

073816AAA Natural Gas Pipeline Geneseo Yes 

077806AAA Ameren Energy Grand Tower Yes 

091801AAH Bunge Foods Corp Bradley Yes 

091804AAB Cognis Corp Kankakee Yes 

091811AAB Natural Gas Pipeline of America Herscher Yes 

093808AAC Natural Gas Pipeline of America Minooka Yes 

097125AAA Abbott Laboratories North Chicago Yes 

097190AAC Midwest Generation LLC Waukegan No 

097809AAD Abbott Laboratories Abbott Park Yes 

115015AAE Archer Daniels Midland Decatur Yes 

115015AAK Caterpillar, Inc Decatur Yes 

115015ABX AE Staley Manufacturing Co Decatur Yes 

143065AJE Archer Daniels Midland Peoria Yes 

143805AAG AES ED Edwards Station Bartonville No 

143810AAG Ameren Energy Mossville Yes 

147802AAB Natural Gas Pipeline of America Hammond Yes 

167120AAO City Water, Light & Power Springfield No 

179020AAB Caterpillar, Inc East Peoria Yes 

179801AAA Midwest Generation LLC Pekin No 

183020ABT Bunge Grain Milling Inc Danville Yes 

197090AAI CITGO Petroleum Corp Lemont Yes 

197800AAA ExxonMobil Oil Corp Joliet Yes 

197800AAC BP Amoco Chemical Co Channahon Yes 

197800AAE Stepan Co Elwood Yes 

197800AAM BASF Corp Channahon Yes 

197809AAO Midwest Generation LLC Joliet No 

197810AAK Midwest Generation LLC Romeoville No 

197817AAA Natural Gas Pipeline of America Shorewood Yes 

138 
7 Conclusion 

This report summarizes and documents Illinois’ 2002 base year inventory of ozone 

precursor emissions. This report includes emissions for the entire state, plus 

identification of emissions for the two nonattainment areas of the state and the 

remaining attainment area. The inventory was developed using actual 2002 emissions 

and data except in cases where noted. 

This document presents the 2002 base year ozone inventory for both typical summer 

day and annual emissions for reactive CO, NOx and VOM from point, area, on-road 

mobile, off-road mobile and biogenic sources for the State of Illinois. In producing this 

document, Illinois EPA has followed the procedures outlined in USEPA’s guidance 

documents pertaining to both preparation and quality assurance of the inventory and 

therefore believes the inventory to be complete, accurate and of high quality. 

Table 7-1: Emission Summary (tons/day) 

Area CO NOx VOM 

Chicago NAA 4,880.04 1,093.01 989.05 

Metro-East NAA 514.02 144.40 218.48 

Attainment Area 4,189.21 1,836.82 3,582.32 

Total 9,583.38 3,074.28 4,789.92 

Table 7-2: Emission Summary (tons/year) 

Area CO NOx VOM 

Chicago NAA 1,631,448.97 343,103.17 261,820.84 

Metro-East NAA 177,472.15 40,178.85 54,729.67 

Attainment Area 1,506,899.25 489,970.80 747,212.46 

Total 3,315,820.44 873,252.94 1,063,762.98 

Table 7-3: Statewide Emission Contributions (percent) 

Category CO 

Daily 

CO 

Annual 

NOx 

Daily 

NOx 

Annual 

VOM 

Daily 

VOM 

Annual 

Point 4.8 2.8 37.4 30.7 6.8 7.2 

Area 0.3 2.8 2.0 5.4 14.2 20.9 

On-Road 49.1 65.3 28.0 35.5 8.3 13.5 

Off-Road 41.2 26.7 27.5 24.0 7.6 8.7 

Biogenic 4.6 2.4 5.2 4.4 63.2 49.7 

139 
Table 7-4: Chicago NAA Emission Contributions (percent) 

Category CO 

Daily 

CO 

Annual 

NOx 

Daily 

NOx 

Annual 

VOM 

Daily 

VOM 

Annual 

Point 3.2 1.6 28.2 15.8 7.7 8.1 

Area 0.4 2.1 3.9 9.4 27.6 34.0 

On-Road 42.5 60.0 37.4 48.9 17.0 22.8 

Off-Road 53.4 36.1 29.9 25.5 23.6 20.3 

Biogenic 0.5 0.3 0.6 0.5 23.9 14.8 

Table 7-5: Metro-East NAA Emission Contributions (percent) 

Category CO 

Daily 

CO 

Annual 

NOx 

Daily 

NOx 

Annual 

VOM 

Daily 

VOM 

Annual 

Point 12.9 10.4 37.6 30.0 8.0 8.7 

Area 0.3 3.7 1.0 4.7 13.7 25.2 

On-Road 54.7 67.5 32.6 42.3 10.8 15.4 

Off-Road 29.0 16.6 25.4 20.0 5.5 5.4 

Biogenic 3.2 1.8 3.4 3.0 62.1 45.2 

Table 7-6: Attainment Area Emission Contributions (percent) 

Category CO 

Daily 

CO 

Annual 

NOx 

Daily 

NOx 

Annual 

VOM 

Daily 

VOM 

Annual 

Point 5.7 3.2 42.9 41.2 6.4 6.8 

Area 0.3 3.5 0.9 2.7 10.5 16.0 

On-Road 56.0 70.8 22.0 25.6 5.7 10.1 

Off-Road 28.5 17.7 26.2 23.2 3.3 4.9 

Biogenic 9.5 4.8 8.0 7.3 74.1 62.3 

Table 7-7: Geographic Contributions (percent) 

Area CO 

Daily 

CO 

Annual 

NOx 

Daily 

NOx 

Annual 

VOM 

Daily 

VOM 

Annual 

Chicago NAA 50.9 49.2 35.6 39.3 20.6 24.6 

Metro-East NAA 5.4 5.4 4.7 4.6 4.6 5.1 

Attainment Area 43.7 45.4 59.7 56.1 74.8 70.2 

140 
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141 
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142 
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143