United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park, NC 27711
EPA-454/R-99-037
September 1999
www.epa.gov/ttn/chief
CDA Handbook for Criteria Pollutant
Inventory Development:
A Beginner's Guide for Point and Area
Sources
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Disclaimer
This document was furnished to the U.S. Environmental Protection Agency (EPA) by Eastern
Research Group, Inc. This document is a final and has been reviewed and approved for
publication. The opinions, findings and conclusions expressed represent those of the authors and
not necessarily those of the EPA. Any mention of company or product names does not constitute
an endorsement by the EPA.
At the time this document was prepared, every effort was made to confirm that all Web addresses
listed were correct. Readers must be aware that Web pages are continually added, updated, and
deleted and that EPA cannot ensure the future accuracy of any reference to the location of
information on World Wide Web. Therefore, it is the readers' responsibility to routinely check
the Web pages for the most current information.
11
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CONTENTS
Section Page
Acronyms, Abbreviations, And Terms x
1.0 INTRODUCTION 1-1
1.1 How Will This Document Help Me? 1-1
1.2 What Assumptions Were Made In Preparing This Document? 1-2
1.3 How Is This Document Organized? 1-2
1.4 How Should I Use This Document? 1-3
1.5 Whom Do I Contact for Help? 1-3
1.5.1 STAPPA/ALAPCO 1-4
1.5.2 Texas Natural Resource Conservation Commission 1-4
1.5.3 California Air Resources Board 1-5
1.5.4 Other Contacts 1-5
2.0 BACKGROUND 2-1
2.1 What Is an Emission Inventory? 2-1
2.2 How Are Emission Inventories Used? 2-4
2.3 Why Is a Complete, Accurate Emissions Inventory Important? 2-4
2.4 What Are Criteria Pollutants? 2-5
2.4.1 Ozone 2-6
2.4.2 Carbon Monoxide 2-6
2.4.3 Nitrogen Oxides 2-6
2.4.4 Sulfur Dioxide 2-6
2.4.5 PM10 and PM2 5 2-7
2.4.6 Lead .' 2-7
2.5 What Is a Point Source? 2-7
2.6 What Is an Area Source? 2-8
2.7 What Does Attainment and Nonattainment Areas Mean? 2-9
in
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CONTENTS (Continued)
Section Page
3.0 OVERVIEW OF THE EMISSIONS INVENTORY PROCESS 3-1
3.1 Why Is Planning Required Before the Inventory Process Begins? 3-1
3.2 What Is an Inventory Preparation Plan and How Can It Help Me? 3-3
3.3 What Resource Issues Must Be Considered? 3-4
3.4 What Are the Main Approaches to Inventory Development? 3-4
3.5 What Types of Emissions Can Be Inventoried? 3-6
3.5.1 What Are Actual Emissions? 3-6
3.5.2 What Are Allowable Emissions? 3-6
3.5.3 What Are Potential Emissions? 3-6
3.6 What Are the Methods for Estimating Emissions? 3-7
3.7 How Do I Select a Method When Multiple Methods Are Applicable? 3-8
3.8 What Data Sources Should I Use? 3-9
3.8.1 Where Do I Find Inventory Guidance? 3-9
3.8.2 Where Do I Find Existing Emission Data? 3-10
3.8.3 Where Do I Find Emission Factor Information? 3-10
3.8.4 Where Do I Find Information on Emission Estimation Models? ....3-12
3.8.5 Where Do I Find Source Characterization Information? 3-12
3.8.6 Where Do I Find Applicable Activity Parameters? 3-14
3.9 What Data Collection Methods Should I Use? 3-16
3.9.1 What Methods Are Used to Collect Data for Point Sources? 3-16
3.9.2 What Methods Are Used To Collect Data For Area Sources? 3-18
3.10 What Is Rule Effectiveness? 3-18
3.11 What Is Rule Penetration? 3-19
3.12 How Should I Document the Emission Inventory Process? 3-20
3.12.1 Why Is Proper Documentation Important? 3-20
3.12.2 What Records Must Be Kept? 3-21
IV
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CONTENTS (Continued)
Section Page
3.13 What Documentation Procedures Must Be Followed? 3-23
3.14 How Do I Track Data Entry? 3-24
3.15 How Do I Check the Accuracy of Data Inputs and Manipulations? 3-24
3.16 How Do I Document QA/QC Procedures? 3-25
3.17 What Data Elements Are Required In The Inventory? 3-25
3.18 How Are the Results of an Emission Inventory Reported to EPA? 3-28
3.19 What Are Emission Projections? 3-30
3.19.1 What Are Baseline Emissions Projections? 3-30
3.19.2 What Are Control Strategy Emission Projections? 3-30
3.20 How Do I Maintain the Emission Inventory? 3-31
4.0 QA/QC PROCEDURES FOR EMISSION INVENTORY PREPARATION 4-1
4.1 Why Is a QA Program Important? 4-1
4.2 What are DQIs? 4-2
4.3 What Are DQOs? 4-3
4.4 What Quality Control Procedures Should I Follow? 4-3
4.4.1 What Is a Reality Check? 4-5
4.4.2 What Is Peer Review and How Does It Benefit the Inventory
Process? 4-6
4.4.3 What Does Replication of Calculations Mean? 4-7
4.4.4 What Are Computerized Checks? 4-8
4.4.5 What Are Statistical Checks and How Are They Used? 4-9
4.5 How Will Quality Assurance Audits Benefit the Emission Inventory
Process? 4-11
4.6 What Types of Errors Are Typically Found in an Emissions Inventory? 4-11
4.7 How Do I Identify and Fill Data Gaps? 4-12
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CONTENTS (Continued)
Section Page
4.8 What Is Double Counting and How Do I Avoid It? 4-13
5.0 POINT SOURCE INVENTORIES OF CRITERIA POLLUTANTS 5-1
5.1 What Sources Should Be Included? 5-1
5.2 How Do I Identify Specific Point Sources in the Inventory Area? 5-4
5.3 At What Level of Detail Are Point Source Inventories Compiled? 5-5
5.4 What Special Issues Should I Consider When Estimating Criteria Pollutant
Emissions from Point Sources? 5-6
5.5 What Emissions Estimation Methods Should I Use? 5-6
5.5.1 Continuous Emissions Monitors 5-10
5.5.2 Source Tests 5-10
5.5.3 Material Balance 5-12
5.5.4 Emission Factors 5-13
5.5.5 Fuel Analysis 5-16
5.5.6 Emission Estimation Models 5-16
5.5.7 Engineering Judgment 5-17
5.6 Is Temporal Allocation Necessary for Point Source Inventories? 5-17
5.6.1 What Is Temporal Allocation? 5-17
5.6.2 How Do I Make Temporal Adjustments? 5-18
6.0 AREA SOURCE INVENTORIES OF CRITERIA POLLUTANTS 6-1
6.1 What Sources Should Be Included? 6-1
6.2 How Do I Identify Area Sources in the Inventory Area? 6-4
6.3 At What Level of Detail Are Area Source Inventories Compiled? 6-5
6.4 What Special Issues Should I Consider When Estimating Criteria Pollutant
Emissions from Area Sources? 6-5
6.5 What Emissions Estimation Methods Should I Use? 6-5
6.5.1 Applying Point Source Methods to Area Sources 6-9
6.5.2 Local Activity Surveys 6-12
vi
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CONTENTS (Continued)
Section Page
6.5.3 Applying a Top-Down Approach 6-12
6.6 Are Temporal and Spatial Allocations Necessary for Area Source
Inventories? 6-15
6.6.1 Is Temporal Allocation Necessary? 6-15
6.6.2 How Do I Make Temporal Adjustments? 6-15
6.6.3 What Is Spatial Allocation? 6-18
6.6.4 How Do I Make Spatial Adjustments? 6-18
7.0 BIBLIOGRAPHY 7-1
8.0 DEFINITIONS OF COMMONLY USED TERMS 8-1
APPENDICES
A List of Available EIIP Documents
B Clearing Up the Rule Effectiveness Confusion
C List of EIIP Preferred and Alternative Methods By Source Category
D Point Sources Example Calculations
E Area Sources Example Calculations
F Overvi ew of Reference Mated al s
G List of Emission Estimation Models and Emission Factor Resources
H List of L&E Documents
I Options for Data Reporting
J 1997 Criteria Pollutants Emissions By Source Category
K List of Potential Point Source Categories By Pollutant
L List of Potential Area Source Categories By Pollutant
M Guidance On How To Conduct Screening Studies
vii
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CONTENTS (Continued)
Section Page
N Sample QC Check List
O Procedures for Developing, Documenting, and Evaluating the Accuracy of
Spreadsheet Data
P List of Relevant Web Sites
Vlll
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CONTENTS (Continued)
Section Page
Tables
2-1 Example Summary of Emission Inventory Results 2-2
3-1 Emission Inventory Data Reporting Elements 3-26
4-1 Primary QA/QC Functions of General Types of Methods 4-4
4-2 Reality Checks Preferred and Alternative Methods 4-6
4-3 Peer Review: Preferred and Alternative Methods 4-7
4-4 Calculation Checks: Preferred and Alternative Methods 4-8
4-5 Summary of Common Automated Checks 4-10
4-6 Source Categories That May Have Area and Point Source Contributions 4-14
5-1 Issues to Consider When Estimating Criteria Pollutant Emissions for Point Sources . 5-7
6-1 Issues to Consider When Estimating Criteria Pollutant Emissions for Area Sources .. 6-6
6-2 Example Area Source Emission Estimation Methods 6-10
6-3 Examples of Surrogate Activity Indicators Applicable to Selected Area Source
Categories 6-16
Figure
3-1 Activities For Preparing an Inventory 3-2
IX
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ACRONYMS, ABBREVIATIONS, AND TERMS
AFS
AIRS
AMS
ANSI
AP-42
ACT
AQCR
AWMA
BID
CAA
CAAA
CARB
CEM
CERCLIS
CFR
CHIEF
CO
CTG
DOT
DQI
DQO
DUNS
EDI
EDR
EFIG
AIRS Facility Subsystem
Aerometric Information Retrieval System
Area and Mobile Source
American National Standards Institute
Compilation of Air Pollutant Emission Factors
Available Control Technique
Air Quality Control Region
Air & Waste Management Association
Background Information Document
Clean Air Act
1990 Clean Air Act Amendments
California Air Resources Board
Continuous Emissions Monitoring
Comprehensive Environmental Response, Compensation, and Liability
Information System
Code of Federal Regulations
Clearinghouse for Inventories and Emission Factors
Carbon Monoxide
Control Techniques Guideline
Department of Transportation
Data Quality Indicator
Data Quality Objective
Dun & Bradstreet
Electronic Data Interchange
Electronic Data Reporting
Emission Factor and Inventory Group
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TABLE OF ACRONYMS, ABBREVIATIONS, AND TERMS (CONTINUED)
EGAS
El
EIA
EIIP
EMTIC
EPA
FIPS
FIRE
GCVTC
GPO
HAP
IDEA
IPP
L&E
MACT
MPS
MSDS
NAAQS
NCASI
NEPA
NESHAP
NET
NMFRC
NCL
A.
NSPS
Economic Growth Analysis System
Emission Inventory
Energy Information Administration
Emission Inventory Improvement Program
Emission Measurement Technical Information Center
United States Environmental Protection Agency
Federal Information Processing Standards
Factor Information Retrieval System
Grand Canyon Visibility Transport Commissions
Government Printing Office
Hazardous Air Pollutant
Integrated Data for Enforcement Analysis
Inventory Preparation Plan
Locating and Estimating
Maximum Achievable Control Technology
Multiple Projection System
Material Safety Data Sheet
National Ambient Air Quality Standards
National Council of the Paper Industry for Air and Stream Improvement
National Environmental Policy Act
National Emission Standards for Hazardous Air Pollutants
National Emission Trends
National Metal Finishing Resource Center
Nitrogen Oxides
New Source Performance Standards
XI
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TABLE OF ACRONYMS, ABBREVIATIONS, AND TERMS (CONTINUED)
NTIS
03
OAQPS
OECA
OTAG
Pb
PCRC
PM
PM25
PM10
POTW
QA/QC
RCRA
RE
RFP
RO
RP
RTKNET
RTF
SAEWG
SARA
sec
SIC
SIP
National Technical Information Service
Ozone
Office of Air Quality Planning and Standards
Office of Enforcement and Compliance Assurance
Ozone Transport Assessment Group
Lead
Paint and Coating Resource Center
Particulate Matter
Parti culate matter with aerodynamic diameter less than or equal to 2.5
microns
Particulate matter with aerodynamic diameter less than or equal to
10 microns
Publicly Owned Treatment Works
Quality Assurance/Quality Control
Resource Conservation and Recovery Act
Rule Effectiveness
Reasonable Further Progress
Regional Office
Rule Penetration
Right-To-Know Network
Research Triangle Park
Standing Air Emissions Work Group
Superfund Amendments and Reauthorization Act
Source Classification Code
Standard Industrial Classification
State Implementation Plan
Xll
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TABLE OF ACRONYMS, ABBREVIATIONS, AND TERMS (CONTINUED)
SO2
sox
STAPPA/ALAPCO
THC
TNRCC
TOC
TRI
TRIS
TSDF
TTN
UATW
USDA
UTM
VMT
VOC
Sulfur Dioxide
Sulfur Oxides
State and Territorial Air Pollution Program Administrators/Association
of Local Air Pollution Control Officials
Total Hydrocarbons
Texas Natural Resource Conservation Commission
Total Organic Compounds
Toxic Release Inventory
Toxic Release Inventory System
Treatment, Storage, and Disposal Facility
Technology Transfer Network
Unified Air Toxics Web Site
United States Department of Agriculture
Universal Transverse Mercator
Vehicle Miles Traveled
Volatile Organic Compound
Xlll
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xiv
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1.0 INTRODUCTION
1.1 How Will This Document Help Me?
This document will help state, local, and tribal air pollution control agency personnel compile an
inventory of criteria pollutant emissions from stationary (point and area) sources. The
information contained in this document is intended to serve as a reference guide only, and
is not intended to serve as new guidance or policy.
This document discusses point and area sources separately. Under ideal circumstances, all
stationary sources would be considered point sources for purposes of developing emission
inventories. In reality, however, only sources emitting more than a specified cutoff level of an air
pollutant are considered point sources. Usually, due to available resources, larger stationary
point sources are typically inventoried individually on a facility-by-facility basis and smaller
sources are usually inventoried collectively as area sources.
This document describes "top-down" as well as "bottom-up" inventory preparation procedures
and contains valuable information on obtaining reference materials (Section 3.4 describes these
two types of procedures). Although this document does not include an exhaustive list of
references, it does provide a list of the most commonly used and readily available materials. This
document also does not mandate specific emission estimation methods, but rather presents those
methods that can be used taking into consideration an agency's resources and goals.
Note: This document does not provide guidance on how to compile an inventory of criteria
pollutant emissions from mobile sources. Mobile sources include all non-stationary
sources. This includes on-highway vehicles (i.e., light-duty cars and trucks, heavy-duty
trucks) and nonroad engines and equipment (i.e., lawn and garden, recreational,
construction, logging, agricultural, industrial, light commercial, airport service, and
recreational marine equipment, as well as commercial marine operations, aircraft, and
locomotives). Guidance on how to compile an inventory of emissions from mobile sources
can be obtained from the EPA's Office of Mobile Sources (OMS) (http://www.epa.gov/oms)
and from the Emission Inventory Improvement Program (EIIP) Mobile Source Committee
(http://www. epa.gov/ttn/chief/eiip/enp_ms. htm).
Note: This document does not provide guidance on how to compile an inventory of
biogenic or geogenic sources. Biogenic sources include vegetation sources (e.g., plants,
trees, grasses, and agricultural activity). Geogenic sources include primarily gas seeps, soil
wind erosion, geysers, and volcanoes. Guidance on how to compile an inventory of
emissions from biogenic and geogenic sources can be obtained from the EIIP Biogenic
Source Committee (http://www.epa.gov/ttn/chief/enp/eiip_bio.htm).
1-1
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1.2 What Assumptions Were Made In Preparing This Document?
This document was prepared based on the following premises:
• That agency personnel using this document lack experience in developing
emission inventories;
• That inexperienced agency personnel have access to useful technical information
within their agency and have experienced state staff or regional office staff
available as a technical resource;
• That all state and local agencies have an existing emissions inventory of criteria
pollutants;
• That all state and local agency personnel have access to the World Wide Web
(Web) and personnel are computer literate;
• That agency managers are responsible for establishing the priority or hierarchy of
source categories and pollutants that will be inventoried; and
• That agency managers are familiar with U.S. Environmental Protection Agency
(EPA) published procedures for compiling emissions inventories.
NOTE: All Web sites referenced in this document were valid at the time this
document was prepared. If you try to use a Web page address and find that it has
expired, check the primary Web address, or call the Info CHIEF help desk at
(919) 541-1000.
NOTE: In addition to available EPA guidance materials, you should become
familiar with basic emission inventory preparation procedures by consulting the
Emission Inventory Improvement Program (EIIP) reference materials described in
Appendix A, or review some of the available materials on the Clearinghouse for
Inventories and Emission Factors (CHIEF) World Wide Web site at
http://www. epa.gov/ttn/chief/.
1.3 How Is This Document Organized?
The document is divided into two major parts. The main body consists of Sections 1 through 7
and presents various tools and techniques you can use to:
• Identify issues to consider when planning and compiling an emissions inventory;
• Identify sources and pollutants of concern;
1-2
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• Locate activity data;
• Locate emission factors; and
• Estimate emissions.
The second part of this document provides a series of appendices that complement the main
body. Each of these appendices serves as a useful source of information for some aspect of
emissions inventory preparation and compilation. The appendices provide greater detail for
estimating emissions and preparing inventories than the main body.
1.4 How Should I Use This Document?
If you are familiar with the inventory development process, characteristics of criteria pollutants,
and general source category definitions, you may want to skip Section 2. Everyone should read
Sections 3 through 6, which contain the detailed information needed to compile an inventory.
If you need information about...
General definitions and uses of inventories
General characterization of criteria pollutants
Issues to consider when planning an inventory
General approaches and methodologies for
estimating emissions and collecting technical
data
How to apply rule effectiveness and rule
penetration to the inventory
Quality assurance and quality control
procedures
Compiling point source inventories
Compiling area source inventories
Resources used to prepare this document
Then read...
Sections 2. 1,2.4, and 2. 5
Section 2.3
Sections 3.1, 3.2, and 3. 3
Sections 3.4 through 3.8
Sections 3. 9 and 3. 10
Section 4
Section 5
Section 6
Section 7
1.5 Whom Do I Contact for Help?
Many agencies in the United States focus their efforts on emission inventory issues. Various
EPA offices and programs and other federal agencies as well as state agencies may be able to
provide information on characterizing and estimating emissions.
1-3
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Potential sources of information among federal agencies include:
EPA's Emission Factor and Inventory Group (EFIG) within the Office of Air
Quality Planning and Standards (OAQPS) (http://www.epa.gov/ttn/chief/efig/);
EPA's Regional Offices;
The U.S. Department of Energy (http://home.doe.gov/); and
The U.S. Department of Agriculture (http://www.usda.gov/).
These federal agencies conduct projects to characterize and assess air pollutants and may have
valuable information pertaining to pollutants and source categories of interest to you.
Potential sources of information among regional, state, and local air pollution
control agencies include:
The State and Territorial Air Pollution Program Administrators
(STAPPA)/Association of Local Air Pollution Control Officials (ALAPCO)
membership directory on the Web at http:www.4cleanair.org; and
State or local air pollution agencies, for example, the Texas Natural Resource
Conservation Commission (TNRCC) and the California Air Resources Board
(CARS).
1.5.1 STAPPA/ALAPCO
STAPPA and ALAPCO are two national associations that represent air pollution control agencies
in the 50 states, 4 U.S. territories, and over 150 major metropolitan areas across the United
States. STAPPA/ALAPCO has participated in several ventures with EPA aimed at improving
the understanding of air pollution issues. For example, the EIIP is a jointly sponsored effort of
STAPPA/ALAPCO and EPA, and is an outgrowth of the Standing Air Emissions Work Group
(SAEWG). STAPPA/ALAPCO also maintains working committees that address modeling and
emission inventory issues. These committees serve as liaisons between EPA and the state and
local air pollution control agencies.
1.5.2 Texas Natural Resource Conservation Commission
TNRCC provides a series of guidance documents on characterizing and estimating emissions
from both point and area sources. The documents provide detailed step-by-step guidance to
assist in calculations. The series is available on the TNRCC Web site at
http://www. tnrcc. state, tx. us/air/nsr_permits/guidedoc. html.
1-4
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1.5.3 California Air Resources Board
One of CARS's stated goals is to continuously improve the understanding of the nature and
causes of California's air quality problems. To achieve this goal, CARB conducts research to
develop and improve emissions estimation methods and emission factors. CARB activities and
publications can be obtained from CARB's Web site at http://www.arb.ca.gov/homepage.htm.
1.5.4 Other Contacts
Several agencies provide public forums for information exchange such as a question and answer
board or "chat room" on their Web site. For example, the OAQPS Emission Inventory (El)
Public Forum is a Web-based discussion site dedicated to the preparation of emission
inventories. Anyone may submit questions, comments, and responses.
The objective of the El Public Forum is to provide an easy and effective venue for seeking and
providing information about air pollution. Because this is a public discussion, statements made
on the El Public Forum do not necessarily represent any official policy. You can access the El
Public Forum on the World Wide Web at http://www.epa.gOV/cgi-bin/netforum/nei/a/l. You
may participate by submitting a message or responding to a previous message.
The Technology Transfer Network (TTN) is operated by OAQPS and includes CHIEF
where you can access the latest information on emission inventories and
emission factors. The CHIEF Forum (http://www.epa.gOV/cgi-bin/netforum/chief/a/l) is another
Web-based discussion site about air emission inventories, emission factors, and closely related
subjects. You may initiate discussion by submitting a message or responding to a previous
message. Because this is a public discussion, statements made on the CHIEF Forum do not
necessarily represent EPA policy.
Examples of topics discussed on the CHIEF Forum are:
Methods for assembling emission inventories;
Methods for arriving at activity levels for area sources; and
Methods for developing emission factors for point and area sources.
1-5
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1-6
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2.0 BACKGROUND
2.1 What Is an Emission Inventory?
An emission inventory is a current, comprehensive listing, by source, of the air pollutant
emissions, and covers a specific geographic area for a specific time interval.
An emission inventory contains the following information:
• Tabular summary of emission estimates by source category. An example is shown
in Table 2-1;
• Background information including the reasons for compiling the inventory;
• Geographic area covered by the inventory;
• Time interval represented by the emissions inventory (e.g., annual, seasonal,
hourly);
• Population, employment, and economic data used to estimate and allocate
emissions;
• Narrative for each source category to include:
Procedures used to collect the data
Sources of data (where data are acquired)
Copies of questionnaires and results (number of questionnaires sent, the
number of responses received, methods for extrapolating data to account
for nonrespondents, and any assumptions made)
Citations for all emission factors
Identification of methods used to calculate emissions, including example
calculations
Complete documentation of all assumptions made
Identification of sources of emissions not included in the inventory
List of references
2-1
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Table 2-1.
Example Summary of Emission Inventory Results
Lead Emissions Estimates, 1996
(Tons per year)
Area Source Category Name
Adhesives and Sealants
Aluminum Foundries
Asphalt Concrete Manufacturing
Autobody Refinishing Paint Application
Aviation Gasoline Distribution: Stage I & II
Brick and Structural Clay Tile
Chemical Preparations
Copper Foundries
Copper Rolling and Drawing
Custom Compound Purchased Resins Manufacturing
Electric Lamps
Electrometallurgical Products Manufacturing
Electron Tubes Manufacturing
Electronic Components, nee
Fabricated Metal Products, nee
Fabricated Rubber Products, nee
Fluid Power Pumps and Motors
Hardware Manufacturing
Hazardous Waste Incineration
Industrial Boilers: Coal, all types
Industrial Boilers: Distillate Oil
Industrial Boilers: Residual Oil
Industrial Boilers: Waste Oil
Industrial Inorganic Chemical Manufacturing
Institutional/Commercial Heating: Anthracite Coal
Institutional/Commercial Heating: Bituminous and
Lignite
Institutional/Commercial Heating: Distillate Oil
Institutional/Commercial Heating: Residual Oil
Metal Heat Treating Manufacturing
SIC
Code
2891
3365
3251
2899
3366
3351
3087
3641
3313
3671
3679
3499
3069
3594
3429
2819
3398
AMS
Code
2301000000
2303000000
2306000000
2401005000
2561000000
2305000000
2301000000
2303000000
2304000000
2401035000
2304000000
2309000000
2308000000
2312000000
2309000000
2601000000
2102000000
2102004000
2102005000
2102012000
2301000000
2103001000
2103002000
2103004000
2103005000
2304000000
Emissions
0.17
0.37
0.043
1.66
0.005
0.005
0.2
3.37
0.26
1.08
0.53
0.29
0.12
0.09
0.11
0.02
0.08
0.12
3.98
0.027
0.011
0.1
0.022
0
0
0.022
0.082
0.034
0.02
2-2
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Table 2-1.
Example Summary of Emission Inventory Results
Lead Emissions Estimates, 1996
(Tons per year) (Continued)
Area Source Category Name
Minerals, Ground or Treated Production
Miscellaneous Organic Chemical Processes
Nonferrous Foundries, nee
Nonferrous Rolling and Drawing
Nonferrous Wire Drawing and Insulating
Open Burning: Scrap Tires
Paints and Allied Products Manufacturing
Plastic Parts and Products (Surface Coating)
Porcelain Electrical Supplies
Power Transmission Equipment
Pressed and Blown Glass and Glassware Manufacturing
Primary Metal Products Manufacturing
Residential Heating: Anthracite Coal
Residential Heating: Bituminous and Lignite Coal
Residential Heating: Distillate Oil
Residential Heating: Wood/Wood Residue
Secondary Nonferrous Metals Production
Stationary Internal Combustion Engines - Diesel
Steel Pipe and Tubes Manufacturing
Steel Wire and Related Products Manufacturing
Storage Batteries Manufacturing
Taconite Iron Ore Processing
Telephone and Telegraph Apparatus
Toys and Sporting Goods
Unsupported Plastics Film & Sheet
Valves And Pipe Fittings, Nee
Vitreous Plumbing Fixtures
SIC
Code
3295
3369
3356
3357
2851
3264
3568
3229
3399
3341
3317
3315
3691
3661
3940
3081
3494
3261
AMS
Code
2305000000
2301000000
2303000000
2304000000
2304000000
2830000000
2301000000
2401035000
2305000000
2312000000
2305000000
2303000000
2104001000
2104002000
2104004000
2104008000
2304000000
2304000000
2304000000
2308000000
2309000000
2305000000
Emissions
0.3
0
0.32
0.62
0
0
0
0.68
0.77
0.12
3.84
0.007
0.006
0.015
0.16
0.78
0.91
0
0.055
1.24
0.21
0
0
0.55
0.01
0.008
2.66
2-3
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2.2 How Are Emission Inventories Used?
Emission inventories are used for a wide variety of purposes, but are most often developed in
response to regulation. Emission inventory data are used to evaluate the status of existing air
quality as related to air quality standards, air pollution problems, assess the effectiveness of air
pollution policy, and to initiate changes as needed. Individual states may have their own specific
inventory requirements, while at the federal level, requirements for emission estimates stem
mainly from the Clean Air Act (CAA).
Emission inventories provide the technical foundation for state, local, and federal programs
designed to improve or maintain ambient air quality. Specific examples of end uses for emission
inventories include:
• Meet CAA mandates for specific inventories as part of State Implementation
Plans (SIPs);
• Tracking progress towards National Ambient Air Quality Standards (NAAQS)
attainment and emission reductions;
• Determine compliance with emission regulations and set the baseline for policy
planning;
• Identifying sources and general emission levels, patterns, and trends to develop
control strategies and new regulations;
• Serve as the basis for modeling of predicted pollutant concentrations in ambient
air;
• Provide input for human health risk assessment studies;
• Conduct environmental impact assessments for proposed new sources;
• Serve as the basis for construction and operating permits;
• Serve as a tool to support future trading programs; and
• Siting ambient air monitors.
2.3 Why Is a Complete, Accurate Emissions Inventory Important?
A technically defensible emissions inventory serves as the foundation for sound public policy.
Formulation of appropriate control strategies requires a reliable base of quality emissions
estimates. If the data used to derive control strategies are flawed, the public policy resulting from
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the strategy will also be in error. These errors can be costly to the public being exposed, the
industry subject to control, and to the environment.
2.4 What Are Criteria Pollutants?
The Clean Air Act directs the EPA to identify and set NAAQS for the most common air
pollutants. EPA uses these "criteria pollutants" as indicators of air quality. These pollutants are:
• Ozone (O3);
• Carbon monoxide (CO);
• Nitrogen oxides (NOX);
Sulfur dioxide (SO2);
• Particulate matter with aerodynamic diameter less than or equal to 10 micrometers
(PM10);
• Parti culate matter with aerodynamic diameter less than or equal to 2.5
micrometers (PM2 5); and
Lead (Pb).
In addition to these pollutants, EPA also regulates emissions of volatile organic compounds
(VOC) under criteria pollutant programs. VOC are ozone precursors—they react with nitrogen
oxides in the atmosphere to form ozone. VOC are emitted from motor vehicle fuel distribution,
chemical manufacturing, and a wide variety of industrial, commercial, and consumer solvent
uses.
EPA's current regulatory definition of VOC (40 CFR § 51.100) excludes constituents considered
to be negligibly photochemically reactive. These include methane, ethane, methylene chloride
1,1,1-trichlorethane (TCA), several Freon compounds, acetone, perchloroethylene, and others. It
is anticipated that additional compounds may be exempted from this VOC definition. The
exempt compounds are considered negligibly reactive, although some can influence the
formation of ozone when present in sufficient amounts. If you encounter a situation where your
emission estimation methodology includes emissions exempted from EPA's definition of VOC,
you should consult with your EPA Regional Office for guidance, and document exactly what
compounds you are reporting as VOC.
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2.4.1 Ozone
Ozone, a colorless gas, is the major component of smog. Ozone is not emitted directly into the
air but is formed through complex chemical reactions between precursor emissions of VOC and
NOX in the presence of sunlight. These reactions are accelerated by sunlight and increased
temperatures. Peak ozone levels typically occur during the warmer times of the year. Ozone
causes health problems because it damages lung tissue, reduces lung function, and sensitizes the
lungs to other irritants.
Ozone occurs in two layers of the atmosphere. The layer surrounding the earth's surface is the
troposphere. Here, ground-level or "bad" ozone is an air pollutant that damages human health,
vegetation, and many common materials. It is a key ingredient of urban smog. The troposphere
extends to a level about 10 miles up, where it meets the second layer, the stratosphere. The
stratospheric or "good" ozone layer extends upward from about 10 to 30 miles and protects life
from the sun's harmful ultraviolet rays (UV-b).
2.4.2 Carbon Monoxide
Carbon monoxide is a colorless, odorless, and poisonous gas produced by incomplete burning of
carbon in fuels. More than 75 percent of the CO emissions in the United States are from
transportation sources, particularly highway motor vehicles. Other major CO sources are
wood-burning stoves, incinerators, and fuel combustion at industrial sources. When CO is
inhaled, it enters the bloodstream, and reduces the delivery of oxygen to organs and tissues.
2.4.3 Nitrogen Oxide?,
Nitrogen oxides are important precursors to both ozone and acid rain, and as a result may affect
not only human health, but also both terrestrial and aquatic ecosystems. Nitrogen oxides can
interact with other compounds in the air to form PM.
Nitrogen oxides form when fuel is burned at high temperatures. The two major emissions
sources are motor vehicles and stationary fuel combustion sources such as electric utility and
industrial boilers. The major mechanism for the formation of nitrogen dioxide (NO2) in the
atmosphere is the oxidation of the primary air pollutant nitric oxide (NO). When inhaled,
nitrogen dioxide can irritate the lungs, cause bronchitis and pneumonia, and lower resistance to
respiratory infections.
2.4.4 Sulfur Dioxide
Sulfur dioxide is a colorless, pungent gas that is a respiratory irritant and like NOX, is a precursor
to acid rain. Sulfur dioxide can also interact with other compounds in the air to form PM. Thus,
sulfur compounds in the air contribute to visibility impairment in large parts of the country that is
especially problematic in national parks. Ambient sulfur dioxide results largely from stationary
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sources such as coal and oil combustion, steel mills, refineries, pulp and paper mills, and
nonferrous smelters.
2.4.5 PM10andPM25
Air pollutants called particulate matter include dust, dirt, soot, smoke, and liquid droplets. PM
originates from a variety of sources, such as:
• Natural sources such as windblown dust and fires;
• Combustion sources such as motor vehicles, power generation, fuel combustion at
industrial facilities, residential fireplaces, and wood stoves. Combustion sources
emit particles of ash or incompletely burned materials;
• Activities such as materials handling, crushing and grinding operations, and travel
on unpaved roads; and
• Interaction of gases (such as NH3, SO2, NOX, and VOC) with other compounds in
the air to form PM.
The chemical and physical composition of PM may vary depending on the location, time of year,
and meteorology. "Fine" particles (PM2 5) are generally emitted from combustion sources.
Sulfate and nitrate secondary particles represent significant components of PM2 5. "Coarse"
particles (PM10) can be emitted from sources including windblown dust, travel on unpaved
roads, and materials handling.
2.4.6 Lead
Elemental lead emitted by stationary and mobile sources can cause several types of
developmental effects in children including anemia and neurobehavioral and metabolic disorders.
Non-ferrous smelters and battery plants are the most significant contributors to atmospheric lead
emissions.
2.5 What Is a Point Source?
Point sources are large, stationary, sources of emissions that release pollutants to the atmosphere.
Point sources are defined as sources that emit quantities above an emission threshold. For
criteria pollutants, the emission thresholds in attainment areas are shown below.
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Pollutant
Carbon monoxide
Nitrogen oxides
Sulfur oxides
Parti culate matter < 10 //m
Particulate matter < 2.5 //m
Lead or lead compounds
Volatile organic compounds0
Emission Threshold for Point
(tons per year)
Sources3
1,000
100
100
100
100 b
5
100
a Emission threshold as stated in 40 CFR 51; Subpart Q 51.322.
b Emission threshold as stated in 40 CFR 51; Subpart 51.025.
c VOCs are not criteria pollutants, but are precursors of the criteria pollutant ozone.
Any stationary source emitting pollutants at levels equal to or greater than those shown in the
preceding table must be inventoried and reported as point sources. In addition, many states also
inventory and report stationary sources below these thresholds as point sources.
Note: Point source thresholds vary in nonattainment areas depending on classification.
2.6 What Is an Area Source?
Area sources are facilities or activities whose individual emissions do not qualify them as point
sources. Area sources represent numerous facilities or activities that individually release small
amounts of a given pollutant, but collectively they can release significant amounts of a pollutant.
For example, a single dry cleaner within an inventory area typically will not qualify as a point
source, but collectively the emissions from all of the dry cleaning facilities in the inventory area
may be significant; thus they must be included in the inventory.
Emission inventories for area sources are usually not compiled using the same methods as
emission inventories for point sources. The level of effort required to collect data and estimate
emissions from the large number of individual facilities or activities would be very high,
especially with respect to the relatively low levels of pollutants emitted by each. To estimate
emissions from area sources, the individual facilities or activities are grouped with like facilities
or activities into broad source categories so that emissions can be collectively estimated using
one methodology. Examples of area source categories include residential wood combustion,
architectural surface coating, pesticide use, prescribed burning, solvent use, and traffic marking.
Unlike point sources for which you collect specific data for each individual source, you will
generally estimate area source emissions by:
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• Using emission factors or allocating national or regional estimates to the local
level; or
• Collecting data for a representative subset of individual area sources. You will
derive emission estimates or activity data for a subset of facilities or activities in
the source category (specific to your inventory area) and scale the estimate to
reflect the entire population of the source category in the inventory area.
2.7 What Do Attainment and Nonattainment Areas Mean?
These designations refer to the compliance status of an area with respect to the NAAQS. An
attainment area is an area considered to have air quality as good or better than required by a
NAAQS. Nonattainment areas have not reached the level of air quality required by a NAAQS.
An area can be an attainment area for one or more pollutants and a nonattainment area for others.
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3.0 OVERVIEW OF THE EMISSIONS INVENTORY PROCESS
This section presents a broad overview of the emissions inventory process, defining terms,
identifying procedures, and providing references for additional information. Figure 3-1
graphically illustrates the activities involved in preparing an inventory.
If you need information about...
Planning the inventory
Top-down and bottom-up approaches
Types of emissions
Methods available for estimating emissions
Selecting methods for estimating emissions
Data sources
Data collection methods
Rule effectiveness
Rule penetration
Documentation of the inventory
Data handling
Required data elements
Reporting results of the inventory
Emissions projections
Inventory maintenance and update
Then read-
Sections 3.1 through 3.3
Section 3. 4
Section 3.5
Section 3.6
Section 3.7
Section 3.8
Section 3. 9
Section 3. 10
Section 3.11
Sections 3. 12 and 3. 13
Sections 3.14 through 3.16
Section 3.17
Section 3. 18
Section 3. 19
Section 3. 20
3.1 Why Is Planning Required Before the Inventory Process Begins?
Careful and thorough planning of the inventory procedures will greatly facilitate the process and
can prevent the need for costly revisions to the inventory during and after review. Air quality
agencies compile emission inventories for a variety of purposes; for example, to provide data
required to evaluate ambient air quality, in response to legislation, or to assess the effectiveness
of an air pollution policy. The anticipated purpose of the inventory will dictate the level of
complexity and accuracy required, but each inventory requires extensive advanced planning.
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Available
Resources
Planning
Status of Existing
Inventory
Identify Inventory
Resolution and
Objectives
Define Point
Source/Area Source
Categories
Identify Data Needs, Available
Information, Data Collection Procedures,
and Emission Estimation Methods
Quality Assurance/
Quality Control and
Documentation
Data Collection
Data Handling
System for
Compilation, Analysis
and Reporting
Calculate
Emissions
Fill Data Gaps
Report Emissions
Figure 3-1. Activities For Preparing an Inventory
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Before the inventory process begins, your agency should prepare an inventory preparation plan to
identify the required staffing levels and resource allocations. The inventory preparation plan will
also specify the methods and procedures to be used by each member of the inventory team to
collect, handle, review, and report emissions data.
3.2 What Is an Inventory Preparation Plan and How Can It Help Me?
An inventory preparation plan (IPP) is a concise, prescriptive document that states exactly how
an agency intends to develop and present its inventory. The plan should include inventory
objectives and general procedures, and should clearly describe how the inventory preparer will
present and document the inventory for submission to EPA and/or others.
As part of the IPP process, you should consider the following:
• End uses of the data;
• Scope of the inventory;
• Availability and usefulness of existing data; and
• Strategy for data collection and management.
Although no specific format is required by EPA, generally, the inventory preparation plan
should:
• Define the geographic inventory area by attainment or nonattainment status;
• Define the scope of the inventory (i.e., identify which sources and pollutants will
be covered);
• Define the data quality objectives;
• Provide the background/basis for the inventory (i.e., describe previous efforts that
are related and describe purpose of this inventory);
• Specify who is responsible for preparing the inventory, with a detailed
organization chart of key personnel/consultants;
• Specify each person's responsibilities;
• Specify the QA coordinator and the technical reviewers (which are different than
the technical team generating the inventory);
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• Describe the approach to be used to estimate emissions (i.e., identify plans for
data collection, analysis, source definition thresholds, emission estimation
methods by source category type, and data reporting and storage procedures);
• Describe QA/QC procedures; and
• Describe how the agency plans to present and document the inventory for
submittal to EPA and/or others.
3.3 What Resource Issues Must Be Considered?
Resources to consider are:
• Time: How much time will it take to gather the information, calculate the
emissions, compile the inventory, and perform the quality assurance/quality
control (QA/QC) tasks? What will the effort cost the agency in labor hours and
time?
• Staff assignment: What experience level is required and who is available to
perform the task?
• Data processing: Do you have adequate computer hardware (including storage
capacity and backup capability) and the necessary software capable of processing
and exchanging data with other organizations?
NOTE: Most of the resource planning issues will be handled by your agency's managers.
However, you should review their plan to make sure that you can accomplish the goals set
by your managers within the allotted resources.
Your managers are responsible for working with you in the planning phase and making decisions
on these issues listed above. Once the uses of the inventory and the constraints on its
development have been identified, data quality objectives (DQOs) can be defined and you can
begin planning your tasks. Section 4.3 discusses DQOs and how to define them for your
inventory development task. In general, the data quality needs of the program will dictate the
level of effort required for planning, executing, and quality assuring the results. The EIIP
guidance series is focused on the emission inventory development process, including planning
and quality assurance activities. For additional information, you should refer to the available
guidance at http://www.epa.gov/ttn/chief/eiip.
3.4 What Are the Main Approaches to Inventory Development?
There are two main approaches that your agency can follow in estimating emissions: the
top-down approach and the bottom-up approach.
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A top-down approach means that your agency develops emission estimates based on
national or regional estimates. You scale the national or regional estimates to your
inventory area using some measure of activity data thought to be directly or indirectly
related to the emissions in your area of study. Typically, sales data, or per employee, or per
capita emission factors are used. For example, the amount of fuel burned in combustion
processes can be used to estimate fuel combustion emissions if you have other known
information such as an emission factor based on pounds of pollutant emitted per gallon of fuel
burned. The total amount of gasoline sold at a gas station is another example of activity data
used to estimate evaporative emissions. The population in an inventory area can be used as the
activity data to estimate VOC emissions from dry cleaning facilities if you have available an
emission factor based on amount of VOC emitted per person.
Characteristics of a top-down approach are:
Typically used to inventory area sources;
Requires minimum resources by grouping like emission sources
together and making use of readily available activity and emission data;
Used when (1) local data are not available, (2) the cost to gather local
information is prohibitive, or (3) the end use of the data does not justify
the cost of collecting detailed site-specific data;
Emission factors or national- or regional-level emissions estimates are
used to estimate emissions in a state or county based on a surrogate
parameter such as population or employment in a specific sector; and
One potential problem with this approach is that an emission estimate
will lose some accuracy due to the uncertainty associated with the
estimate and the representativeness of the estimate once extrapolated to
the local level.
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A bottom-up approach means you estimate emissions for individual sources and sum all
sources to obtain state- or county-level estimates.
Characteristics of a bottom-up approach are:
Typically used to inventory point sources; however, it can be used to
inventory area sources when resources are available to collect local
activity data through a survey effort.
Requires more resources to collect site-specific information on emission
sources, activity levels, and emission factors; and
Results in more accurate estimates than a top-down approach because
data are collected directly from individual sources and not derived from
a national or regional estimate.
3.5 What Types of Emissions Can Be Inventoried?
Irrespective of whether a top-down or a bottom-up approach is used, inventories can be compiled
using actual emissions, allowable emissions, or emissions based on a facility's potential to emit
(potential emissions) depending on the purpose of the inventory. Each type of estimate is
described in more detail below.
3.5.1 What Are Actual Emissions?
Actual emissions are defined as the actual rate of emissions of a pollutant from a source (or
emission unit within a source) calculated using actual operating hours, production rate, and
where applicable, fuel combusted during the period of interest. For example, base year
inventories developed in support of a SIP are compiled using actual emissions.
3.5.2 What Are Allowable Emissions ?
Allowable emissions are the product of an enforceable emissions rate (e.g., pounds of VOC per
gallon of solids applied), the anticipated operating rate or activity level (e.g., gallons of solids
applied per hour), and the anticipated operating schedule (hours per day). In general, allowable
emissions are used when emission projections are being developed for use in SIP modeling.
3.5.3 What Are Potential Emissions?
Potential to emit (i.e., potential emissions) is the capability of a source, at maximum design
capacity, to emit a pollutant after the application of air pollution control equipment. Potential to
emit estimates are based on the maximum capacity of a source after taking into consideration
enforceable permit conditions such as the type of materials combusted, the type of material
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processed, and the annual hours of operation. In general, potential emissions are estimated and
reported in inventories in support of permitting activities under Title V of the CAA.
3.6 What Are the Methods for Estimating Emissions?
The methods most commonly used in estimating emissions of criteria pollutants include:
• Continuous emission monitors (CEMs): CEMs continuously measure (with very
short averaging time) and record actual emissions during the time of monitor
operation. CEMs data can also be used to estimate emissions for different
operating and longer averaging times.
• Source testing: Emission rates are derived from short-term emission
measurements taken at a stack or vent. Emission data can then be extrapolated to
estimate long-term emissions from the same or similar sources.
• Material balance: Emissions are determined based on the amount of material that
enters a process, the amount that leaves the process, and the amount shipped as
part of the product itself.
• Emission factors: An emission factor is a ratio that relates the emission of a
pollutant to an activity level at a plant that can be easily measured, such as an
amount of material processed, or an amount of fuel used. Given an emission
factor and a known activity level, a simple multiplication yields an estimate of the
emissions. Emission factors are developed from separate facilities within an
industry category, so they represent typical values for an industry, but do not
necessarily represent a specific source. Published emission factors are available in
numerous sources.
• Fuel analysis: Emissions are determined based on the application of conservation
laws. The presence of certain elements in fuels may be used to predict their
presence in emission streams. For example, SO2 emissions from oil combustion
can be calculated based on the concentration of sulfur in the oil. This approach
assumes complete conversion of sulfur to SO2. Therefore, for every pound of
sulfur (molecular weight = 32g) burned, two pounds of SO2 (molecular
weight = 64g) are emitted.
• Emission estimation models: Emission estimation models are empirically-
developed process equations used to estimate emissions from certain sources. An
example emission estimation model is the TANKS software for estimating
volatile organic compounds emissions from fixed- and floating-roof storage tanks.
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• Surveys and questionnaires: Surveys and questionnaires are commonly used to
obtain facility-specific data on emissions and their sources.
• Engineering judgment: An engineering judgement is made when the specific
emission estimation techniques such as stack testing, material balance, or
emission factor are not possible. This estimation is usually made by an engineer
familiar with the specific process, and is based on whatever knowledge may be
available.
These methods, and their applicability, are described in detail in Sections 5 and 6 of this
document Appendix C lists the EIIP point and area source categories and their applicable
preferred and alternative emissions estimation methods. In addition, Appendices D and E
provide example calculations on the use of these methods in estimating emissions from
point and area sources, respectively.
3.7 How Do I Select a Method When Multiple Methods Are Applicable?
Selecting a method to estimate source specific emissions warrants a case-by-case analysis
considering the cost and required accuracy in the specific situation. When selecting an emissions
estimation method, you should consider several issues when analyzing the tradeoffs between cost
and accuracy of the resulting estimates. These issues include:
• Availability of quality data needed for developing emissions estimates;
• Practicality of the method for the specific source category;
• Intended end use of the inventory (e.g., an inventory in support of significant
regulatory implications such as residual risk or environmental justice issues may
require that more accurate and costly emission estimation methods be used than
would an inventory intended for simply a source characterization);
• Source category priority (e.g., if a source category is of relatively high priority, it
may require a more accurate emission estimation method);
• Time available to prepare the inventory; and
• Resources available in terms of staff and funding.
To help you decide which estimation methods to use, you should refer to the EIIP series of
documents. An important aspect of the EIIP's selection of methods was the identification of
"preferred" and "alternative" methods. Refer to Volume I of EIIP for a complete discussion on
how to select emission estimation methods Appendix A provides a complete list of available
EIIP documents.
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3.8 What Data Sources Should I Use?
This section introduces the various data sources available to you in compiling an emissions
inventory. The types of data you will need to compile a complete emissions inventory include:
• Inventory guidance;
• Existing emission data;
• Emission factor resources;
• Models resources;
• Source characterization documents (documents that characterize an industry,
including a description of processes, operating parameters, equipment used,
emissions generated; and volume and type of output produced); and
• Activity data references.
Note that in many cases a single document can provide information on one or more of the types
of data needed for your inventory. For example, EIIP is an excellent resource for inventory
guidance as well as source characterization, andAP-42 is an excellent resource for both emission
factors and source categorization.
3.8.1 Where Do I Find Inventory Guidance?
The primary guidance on emission inventory development is summarized in the EIIP volumes.
The EIIP volumes were developed through a joint process involving state and local agencies and
EPA. These volumes present EPA's recognized standard for the development of reliable,
quality-rated inventories. The EIIP documents present preferred and alternative methods for
estimating emissions from point, area, mobile, and biogenic source categories. A complete list
of EIIP documents is provided in Appendix A Hard copies of these manuals are available
from the National Technical Information Service (NTIS). Electronic copies of the EIIP
documents can be downloaded off the World Wide Web through the EIIP Web site at
http://www.epa.gov/oar/oaqps/eiip/.
Additional emissions inventory guidance, such as memoranda from OAQPS, can be downloaded
off the World Wide Web through EPA's CHIEF Web site at
http://www. epa.gov/tin/chief/ei guide. html#egmemo and
http://www.epa.gov/ttn/chief/reptdesc.html. For example, one guidance document published by
EPA is the 7995 Protocol for Equipment Leak Emission Estimates (EPA, 1995a).
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3.8.2 Where Do I Find Existing Emission Data?
A well-documented, existing air emissions inventory is a good source of emissions data. If an
agency has previously estimated emissions based on a survey of the industry, sometimes you can
use those data to estimate emissions for the newer inventory. This may be as simple as applying
a growth factor to the emissions, or it may require further adjustments to account for other
changes in the industry such as new controls. Information contained in these inventories can at
least serve as a starting point for developing extensive data and support information, such as
documentation of procedures.
NOTE: Many existing inventories may focus on pollutants other than those needed in the
inventory being prepared. Thus, certain sources that emit only one type of pollutant may
not be well represented
The most current and accessible national emission databases available for review and assessment
in developing a criteria air pollutants inventory include:
• The National Emission Trends (NET) Database:
FTP://www. epa.gov/pub/EmisInventory;
• Aerometric Information Retrieval System (AIRS): (800) 334-2405 or
(919)541-7862; and
• AIRSWeb: http://www.epa.gov/airsweb/sources.htm.
Detailed descriptions of these databases are provided in Appendix F.
A less desirable but possible source of emissions data is through the extrapolation of emissions
from one geographic region to another. This approach may be most appropriate when the
socioeconomic conditions between two regions are comparable. In these situations, the
emissions data for one region can be extrapolated to the other region based on population,
employment, or other representative surrogates of the activity causing the emissions.
3.8.3 Where Do I Find Emission Factor Information ?
The most commonly used emission factor resources are listed below and described in
greater detail in Appendix G.
• AP-42: One of the most frequently cited resources for emission factor
information is the EPA document, Compilation of Air Pollutant Emission Factors
(AP-42). This document contains criteria pollutant emission factors for point and
area sources. AP-42 is available on the World Wide Web at
http://www.epa.gov/ttn/chief/ap42.html. AP-42 is also available on the Air
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CHIEF CD-ROM, and in hard copy from the Government Printing Office (GPO)
at (202)512-1800.
• Emission factor databases: Several emission factor databases are currently
available in easy-to-access formats to state and local agencies. Two of these tools
include:
Factor Information Retrieval (FIRE) Data System (EPA, April 1999a),
http://www. epa.gov/ttn/chief/fire. html
Air Clearinghouse for Inventories and Emission Factors (Air CHIEF)
CD-ROM, http://www.epa.gov/ttn/chief/airchief.htmffiorder or
(202)512-1800.
In addition, you should conduct a search of technical papers for source test and background
information for the emission source category or pollutants in question. You can conduct this
search using EPA library services or through government document depositories at local
universities. Examples of references and documents that you should review include:
• Miscellaneous private sector resources. For example, the National Council of the
Paper Industry for Air and Stream Improvements, Inc. (NCASI) compiles, through
a highly focused research program, reliable environmental data and information
on the forest products industry.
• Emission factor reports published by other state and local agencies, and other
states' databases and source tests. This information can be identified and acquired
through direct communication with the agencies.
• Source test data used for compliance purposes and in developing operating
permits for stationary sources may be readily available through state and local air
permitting agencies. The use of source test data reduces the number of
assumptions regarding the applicability of emission factors to a source.
• Professional societies (e.g., AWMA) symposia publications contain up-to-date
information.
Additional databases and documents that contain emission factors for use in inventories are listed
in the applicable source methodology chapters in EIIP Volumes n and HI.
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3.8.4 Where Do I Find Information on Emission Estimation Models?
Several emission estimation models are available for download free-of-charge.
• Landfill Gas Emissions Model (EPA, June 1999)
http://www. epa.gov/ttn/catc/products. html#software
• TANKS to estimate emissions from fixed- and floating-roof storage tanks (EPA,
May 1999) http://www.epa.gov/ttn/chief/tanks.html
WATERS (EPA, November 1995) and CHEMDAT8 (EPA, November 1994) to
estimate air emissions from wastewater collection and treatment systems
http://www. epa.gov/ttn/chief/software. html#water8
• MECH for estimating participate emissions from paved roads, unpaved roads,
materials handling, agricultural tilling and construction and demolition (EPA,
August 1992b) http://www. epa.gov/ttn/chief/software. html#fugitive
• PM Calc for estimating PM2 5 emissions (EPA, May 1998)
http://www. epa.gov/ttn/chief/software. html#fugitive
3.8.5 Where Do I Find Source Characterization Information ?
You will need source categorization information to identify the sources you must include in
the inventory. Source categorization information includes:
• Description of the sources, facilities, or activities included in the source category.
For example, the boiler source category comprises sources that combust fuels to
produce hot water and/or steam. The source category definition can include the
SIC code or the EPA AIRS AMS source category code.
• Description of emission sources within the source category. For example, the
boilers category includes coal-fired boilers, oil-fired boilers, boilers using other
types of fuel, cogeneration units, and auxiliary sources.
• Discussion of the factors influencing emissions such as control techniques,
influences of weather conditions, or process operating factors.
Several resources are available to you for source characterization. Primary resources include:
• AP-42: See Section 3.8.3 for a description.
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Locating and Estimating Air Emissions from Sources of (Source Category or
Substance) (L&E) Documents. About 30 L&E documents are currently available.
Although L&E documents concentrate on hazardous air pollutants (HAPs), these
documents can be useful for criteria pollutant inventories because each volume
includes general descriptions of the emitting processes, and provides source
characterization. L&E documents are available on the CHIEF Web site at
http://www.epa.gov/ttn/chief/ap42etc.htmMLE. A complete list of L&E
documents is included in Appendix H.
Industry Sector Notebooks: The EPA's Office of Compliance has developed a
series of notebooks profiling selected major industrial groups. Each
sector-specific notebook brings comprehensive details that include an
environmental profile, industrial process information, and bibliographic
references A detailed description of the Industry Sector Notebooks project is
provided in Appendix F. Industry Sector Notebooks are available on the World
Wide Web at http://es.epa.gov/oeca/sector/index.html
Additional resources include:
EPA reports presenting the results of engineering investigations of air emissions
from various industrial processes, such as Control Techniques Guidelines (CTGs)
and Available Control Techniques (ACT) documents, and Background
Information Documents (BIDs) for New Source Performance Standards (NSPS)
and National Emission Standards for Hazardous Air Pollutants (NESHAP) or
Maximum Achievable Control Technology (MACT) standards. These reports are
available through the GPO, the National Technical Information Service (NTIS),
and on the World Wide Web at http://www.epa.gov/ttn/
The Integrated Data for Enforcement Analysis (IDEA) system: IDEA is an
interactive data retrieval and integration system developed by EPA's Office of
Enforcement and Compliance Assurance (OECA). IDEA integrates facility data
across EPA's various program office databases. A detailed description of IDEA
is provided in Appendix F and on OECA's Web site at
http://es. epa.gov/oeca/idea/
Air pollution control agency files: Compliance, enforcement, permit application,
or other air pollution control agency files may provide valuable information on the
location and types of sources in the area of concern. For example, permit
applications generally include enough information about a point source to
describe the nature of the source and to estimate the magnitude of emissions that
will result from its operations. A compliance file might contain a list of air
pollution regulations applicable to a given source, a history of contacts made with
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that source on enforcement matters, and an agreed-upon schedule for the source to
effect some sort of control measures.
• Annual emission statements: Most states require facilities emitting above a
certain threshold to submit an annual emission statement listing various processes
and their emissions. Annual emission statements should be examined to
determine whether the appropriate sources have been included and that the
emissions data represent current conditions.
• Other government-funded agencies, such as the Paint and Coating Resource
Center (PCRC) and the National Metal Finishing Resource Center (NMFRC):
The main function of these Centers is to provide regulatory compliance and
pollution prevention information on their respective industries. The PCRC can be
accessed on the World Wide Web at http://www.paintcenter.org/and the NMFRC
can be accessed at http://www.nmfrc.org/.
3.8.6 Where Do I Find Applicable Activity Parameters?
You may need to use different types of activity data to estimate emissions from area and point
sources - even within the same source category. Point sources may require direct measurement
or direct activity (i.e., throughput) applied to an emission factor, while emissions from area
sources are often estimated using surrogate activity factors, such as population or employment.
Activity Parameters for Point Sources
For point sources, activity parameters are generally reported as fuel consumption rates or process
weight rates for fuel-burning equipment and industrial processes, respectively. You will need
detailed data on process equipment, throughput, capacity, and other parameters to estimate
emissions from point sources. You can obtain this information from contacts with individual
facilities. The two most common types of plant contacts are (1) surveys and questionnaires, and
(2) direct plant inspections. A type of indirect plant contact also commonly employed is the use
of permit applications or compliance files. Other traditional sources of activity data for point
sources include:
• State and local industrial directories;
• State Departments of Commerce and Labor statistics;
• National and state directories of manufacturers;
• Data compiled by private research and development companies such as the
Directory of Chemical Producers compiled by SRI International; and
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• Trade and professional associations.
Activity Parameters for Area Sources
Area source emission estimates are generally based on surrogate activity data and an emission
factor developed specifically for that activity. Activity data include population, employment,
fuel or product usage, product sales, and types of land use correlated with air emissions.
Traditional sources of activity data for area sources include:
• U. S. Department of Commerce publications including County Business Patterns,
Census of Population, Census of Manufacturers, Census of Agriculture, County
and City Data Book, Current Industrial Reports, Annual Housing Survey, and
Census of Retail Trade;
• U. S. Department of Energy publications such as State Energy Data Reports,
Natural Gas Annual, and Petroleum Marketing Annual;
• State Departments of Transportation and State Energy Offices (for information on
gasoline consumption and paving activities);
• State Departments of Labor (for employment data by SIC [Standard Industrial
Classification] code)
• Local industrial directories (these are often organized by SIC code and provide
employment data);
• Regional planning commissions;
• Agency-sponsored surveys;
• State Agricultural Offices and U.S. Department of Agriculture (for pesticide
application data);
• State Solid Waste Management Agencies;
• Fire marshals (for information on structural fires);
• Port authorities and waterborne commerce (for information on petroleum vessels
loading and unloading activities);
• State Health Departments (for information on hospital sterilizers); and
• Miscellaneous statistical government and trade group publications.
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The first 5 sources of information listed are generally the most widely used and provide a great
deal of useful information.
3.9 What Data Collection Methods Should I Use?
This section presents information on the different data collection approaches to be used when
inventorying point and area emissions sources.
3.9.1 What Methods Are Used to Collect Data for Point Sources?
For point source inventories, you can obtain information by contacting each point source in the
inventory area. The two most common types of plant contacts are:
• Surveys; and
• Plant inspections
You can also use indirect plant contact techniques to gather data for point source inventories,
such as examining state files (permit applications and compliance files).
You may need to use a combination of data gathering techniques to ensure complete and accurate
data are available for compilation of an inventory. Appropriate method(s) are selected during the
planning phase of the inventory process, based on data quality objectives and availability of
resources.
Surveys
You can use the survey technique to obtain source and emissions data, sending a questionnaire to
each point source in the inventory area. To conduct a survey you will need to:
• Identify the facilities to be surveyed;
• Prepare the mailing list, including facility addresses and appropriate plant contact
personnel;
• Design and assemble the questionnaire;
• Deliver the questionnaire;
• Establish tracking systems to monitor the status of each step in the survey process;
• Prepare data handling procedures; and
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• Establish systems to respond to questions or concerns of survey recipients.
While paper questionnaires and return forms are still in use, it is rapidly becoming more common
for these forms to be sent to sources, and responses to be returned, in an electronic format. You
can send questionnaires to facilities via e-mail, or post them on the Internet. By using
standardized electronic forms for data submittal, you can simplify the process for both the
surveyed facilities and your agency. Electronic data systems reduce the chance of data entry
errors by inventory preparers.
Appendix M provides a detailed description of how to conduct a survey.
Plant Inspections
Plant inspections give you the opportunity to examine the various processes at a particular
facility, interview plant personnel, and review operations and process schematics. While plant
inspection is a very resource-intensive data collection technique, it has several advantages over
the survey technique:
• Plant inspection provides more complete and accurate information about a facility
than a questionnaire;
• Plant inspection allows you to obtain a more complete understanding of an
exceptionally complex or unique process;
• Plant inspections reduce errors that can result from misinterpretation of a question
by the plant contact responding to the survey; and
• Plant inspections reduce errors that can result from the inventory agency
misinterpreting a response by the plant contact.
Examination of State Files
You can also use files maintained by your state/local agency as sources of information. Files that
might include data relevant to emissions inventories include:
• Permit files: Permits are generally required for construction, start-up,
modifications, and continuing operation of existing facilities. Permit applications
include information that can be useful to describe the nature of the source and to
estimate the magnitude of emissions that might result from operations.
• Compliance files: Some agencies also maintain compliance files for point
sources. These files contain records of communication concerning enforcement
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issues, as well as a list of air pollution regulations applicable to the specific
source.
3.9.2 What Methods Are Used To Collect Data For Area Sources?
Data sources for area source inventories vary much more than those for point sources. You will
collect area source data from a number of diverse sources.
Surveys
You can use surveys of a representative sample to collect data that can be extrapolated to the area
source category. You must use caution to ensure that the surveyed subset is representative of the
entire population. You may use the same steps to survey area sources as you use for point
sources, but often the steps taken are driven by available resources and data.
Appendix M provides a detailed description of how to conduct a survey.
Examination of Local. State, and Federal Documents and Databases
State, local, and federal agencies such as the U.S. Bureau of the Census and the Energy
Information Administration generate summary reports containing information on population
trends, land use, business patterns, agricultural trends, fuel use, chemical production and use, and
meteorological conditions. You will find that these documents are often valuable resources for
determining appropriate activity data or parameters for apportioning data. Many of these
documents are available on the Internet. You may also find that personnel at these agencies can
be valuable data resources.
Examination of Trade Association Reports. Journals, and Databases
Trade association documents, journals, and market research reports can provide information on
past sales and future trends for specific industry sectors. You can use this information to
determine appropriate activity data or parameters for apportioning data.
3.10 What Is Rule Effectiveness?
Regulatory programs often achieve fewer reductions than anticipated for most source categories
in most areas of the country. Rule effectiveness (RE), expressed as a fraction or percent, is an
adjustment which reflects the ability of a regulatory program to achieve the required emission
reductions. The intent behind the RE factor is to account for the fact that most emission control
equipment does not achieve emission reductions at the designed rates at all times and under all
conditions, and that some intentional noncompliance exists. Process upsets, control equipment
malfunctions, operator errors, equipment maintenance, and other non-routine operations are
examples of times when control device performance is expected to be less than optimal.
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Rule effectiveness should be applied for all applicable regulations whether federal, state, or local.
Therefore, the RE factor applies to both point and area sources that are controlled. No RE
is needed in cases where no control is applied or there is no applicable regulation.
You should take several factors into account when estimating the effectiveness of a regulatory
program. These include:
• The nature of the regulation (e.g., whether any ambiguities or deficiencies exist,
whether test methods and/or recordkeeping requirements are prescribed);
• The nature of the compliance procedures (e.g., taking into account the long-term
performance capabilities of the control);
• The performance of the source in maintaining compliance over time (e.g., training
programs, maintenance schedule, recordkeeping practices); and
• The performance of the implementing agency in assuring compliance (e.g.,
training programs, inspection schedules, follow-up procedures)
The basic emission estimation equation when RE is applied:
Ec = Euc x (1 - CE x RE)
where:
Ec = Emissions after control
Euc = Emissions before control
CE = Estimated control efficiency (expressed as a fraction)
RE = Rule effectiveness (expressed as a fraction)
Additional guidance on estimating and applying RE is provided in the draft paper titled
Clearing Up the Rule Effectiveness Confusion which is presented in Appendix B. Another
draft paper, Emission Inventories and Proper Use of Rule Effectiveness is available online from
the EIIP at http://www.epa.gov/ttnchiel/eiip/pointsrc.html.
An example of the use of RE is provided in Appendix E, Example 10.
3.11 What Is Rule Penetration?
Another important regulatory consideration is the extent to which a regulation covers emissions
from an area source category. Rule penetration (RP) is the percentage of an area source
category that is covered by an applicable regulation. For example, regulations on gasoline
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underground tank filling may apply only to stations above a specified size cutoff, or the
regulation may apply to facilities built after a certain date.
When estimating emissions using area source methods for source categories where a rule or
regulation applies, agencies should incorporate an estimate of the amount of rule penetration.
Use this formula to apply RP:
„,„,,. ( Uncontrolled emissions covered by the regulation) 1Ano/
Rule Penetration = J- 2 x 100%
I Total uncontrolled emissions J
An example of the use of RP is provided in Appendix E, Example 10.
3.12 How Should I Document the Emission Inventory Process?
This section presents proper documentation procedures that should be followed by the inventory
preparer.
3.12.1 Why Is Proper Documentation Important?
Complete and well-organized documentation is necessary to prepare a reliable and technically
defensible inventory document. The goal of inventory documentation is to ensure that the final
written compilation of the data accurately reflects the inventory effort.
In addition, thorough documentation is necessary to:
• Support QA/QC assessments of the inventory. During the inventory compilation
process, QA/QC and technical review of the documentation can identify errors in
assumptions, calculations, or methods. Remedial actions can be taken to correct
any errors.
• Ensure the reproducibility of the inventory estimates. The inventory
documentation should include all of the information necessary for an inventory
user or reviewer to reproduce the results of each estimate. A well-documented
inventory will provide a "paper trail" for each data point, allowing a user or
reviewer to identify all of the resources used to calculate each value presented in
the report.
• Enable an inventory user or reviewer to assess the quality of the emission
estimates and identify the data references.
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• Ensure that the inventory will serve as a solid foundation for future inventories
compiled for that inventory area.
3.12.2 What Records Must Be Kept?
The documentation of an inventory compilation process involves two phases:
• Documentation of all data collection and emission estimation activities; and
• Compilation of the inventory into a final written report.
Documentation of data collection and emission estimation activities includes the daily
recordkeeping that occurs during the inventory preparation process. This documentation is
critical to both the integrity of the inventory process and the preparation of the final report. The
procedures you use for documentation will be established in the inventory preparation plan (See
Section 3.3).
Documentation includes:
• Complete documentation of methods used for all data collection, including
explanation of any deviations from the prescribed methods;
• Explanation of all assumptions made in the data collection or analysis;
• All raw data, including identification of the source of each data point;
• All calculations, including copies of work conducted manually and all electronic
spreadsheets or databases;
• Records of all relevant communication with team members and data contacts;
• QA/QC records, including responses to issues identified by audits; and
• Identification of sources of emissions not included in the inventory.
The source and type of the raw data will determine what type of information you need to place in
the project file.
If the data were collected Then you must maintain the following
from... records-
Surveys Original survey forms
Site visits Site visit notes and reports
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If the data were collected
from...
Then you must maintain the following
records-
Source test reports
Complete copies of the reports
Internet pages or electronic
bulletin boards
- Hard copy printouts of the pertinent data
- Electronic copies of complete original data
- Complete reference citation
Published document
- Complete reference citation
- When possible, copies of the pages with the
data used in the inventory
Unpublished documents or
reports
Complete reference citation
Copies of all pages with data used in the
inventory
When possible, a copy of the entire document
Personal communication -
written
Complete reference citation (contact name,
affiliation, address or phone number, data of
communication)
Copies of all pages with data used in the
inventory
When possible, a copy of the entire document
Personal communication -
verbal
Standardized Contact Report Form should be
completed to record information obtained by
telephone or at a meeting. An example Contact
Report form is presented in EIIP Volume VI,
Chapter 2.
You should include the following information on all manual calculation sheets:
• Preparer' s name;
• Date prepared;
• Date modified, if applicable;
• Signature of reviewer;
• Date of review;
• References and documentation for all data used in the calculation;
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• Explanation of all assumptions; and
• Page number on each page, showing total number of pages.
You must also document calculations performed using spreadsheets. The spreadsheet contains
all of the pertinent information used to estimate emissions, but much of the information is often
hidden on the summary printout. You must be certain that spreadsheets include the following
information:
• Preparer' s name;
• Date prepared;
• Date modified, if applicable;
• Spreadsheet version number;
• Name of reviewer;
• Date of review;
• All constants, factors, or other data used in the calculations must be presented;
that is, all data needed to reproduce the value should be shown;
• Citations for all data used in the calculation;
• Explanation of all assumptions; and
• Page number on each page, showing total number of pages.
Refer to Appendix N for detailed instructions on procedures to follow when developing,
documenting, and reviewing spreadsheet data.
3.13 What Documentation Procedures Must Be Followed?
For all steps in the inventory process, you should follow these procedures:
• Each member of the project team should be assigned a numbered, project-specific,
notebook for recording all calculations and assumptions;
• All entries should be initialed and dated;
• Calculations and documentation should be done in ink - not pencil; and
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• Errors should be corrected by drawing a single line through the original entry and
writing the correct value nearby. All corrections must be initialed and dated by
the person making the change.
In order to maintain credible inventory records, the inventory preparation plan will establish
documented procedures for:
• File contents: Each member of the team should be aware of what materials must
be placed in the project files;
• Location of all paper and electronic records;
• Ensuring that all hard copy records, as well as electronic databases and
spreadsheets, are kept up-to-date;
• Adding data or background documentation to the file, including log-in procedures;
• Data tracking: To document who entered or manipulated data;
• Access to files: Checkout policies for paper documents, computer security
policies for electronic files;
• Backup and maintenance of electronic files; and
• File name conventions.
3.14 How Do I Track Data Entry?
The procedures you use for tracking data entry will be established in the inventory preparation
plan. Emissions inventory efforts often generate large quantities of data from a variety of
sources. Development of emissions estimates generally requires data manipulation, including
manual calculations, electronic data entry into computer programs, and data checking activities.
Sometimes data will change hands several times during the emissions estimation process. This
makes it very important that you use the procedures prescribed in the inventory preparation plan
to record the names of the persons responsible and the dates of each data manipulation activity.
3.15 How Do I Check the Accuracy of Data Inputs and Manipulations?
The procedures you use for checking the accuracy of data entry and calculations will be
established in the inventory preparation plan. It may be possible to build some of these checks
into the computer database that is handling the data. For example, a computer program can be
set to reject an entry that exceeds a reasonable or expected value. More often, manual QC
checks, tracking the data from receipt to final result, are necessary.
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It is important to check the transcription of data during the inventory preparation. Data
manipulation steps that you need to monitor include:
• Transcription of data from raw data sheets into electronic spreadsheets or for use
in manual calculations;
• Transcription of data results into summary tables or reports.
You must also have procedures in place to confirm the accuracy of calculated values. Many of
these checks can be conducted with computer programs, others will require manual checks.
Refer to Appendix N for guidance on evaluating accuracy of spreadsheet data.
3.16 How Do I Document QA/QC Procedures?
Each member of the inventory project team should follow the QA/QC documentation procedures
prescribed in the inventory preparation plan. All QA/QC activities and results must be
documented and reported, either as part of the inventory report, or as a separate document. The
report should include:
• Procedures used to meet the QA/QC objectives of the project;
• Technical approach used to implement the QA plan;
• Dates of each audit, and the names of the reviewers;
• Results of QA activities, including problems found, corrective actions, and
recommendations; and
• Discussion of the inventory quality.
3.17 What Data Elements Are Required In The Inventory?
The data elements shown in Table 3-1 should be reported in the inventory. The term data
element refers to any piece of information used in the inventory compilation process. You will
use many types of data, and collect it from a wide range of data sources.
These data element requirements may be modified over time and your agency should contact the
EPA Regional office for the most recent list of required data elements.
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Table 3-1.
Emission Inventory Data Reporting Elements
Data Element Point Sources Area Sources
Start date (Inventory year)
State Federal Information
Processing Standards (FIPS) code
County FIPS code
Federal ID code (plant)
Federal ID code (point)
Federal ID code (process)
Site name
Physical address
SIC code
sec
Heat content (fuel, annual)
Pollutant code
Activity/throughput (annual)
Work weekday emissions
Summer/winter work weekday
emissions
Annual emissions
Emission factors
Winter throughput (%
Spring throughput (%)
Summer throughput (%)
Fall throughput (%)
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Table 3-1.
Emission Inventory Data Reporting Elements (Continued)
Data Element Point Sources Area Sources
Hours per day in operation
Start time (hour)
Days per week in operation
Weeks per year in operation
Federal ID code (stack number)
X coordinate (latitude)
Y coordinate (longitude)
UTM coordinates
Stack height
Stack diameter
Exit gas temperature
Exit gas velocity
Exit gas flow rate
Boiler design capacity
Maximum design rate
Maximum nameplate capacity
Primary control efficiency (%)
Secondary control efficiency (%)
Control device type
Control efficiency
Rule effectiveness %
Rule penetration (%
Source: EPA, 1999b
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3.18 How Are the Results of an Emission Inventory Reported to EPA?
Your report must meet the format and content requirements specified by the regulation or the
agency requiring the inventory. Information on the data and documentation that you are required
to submit is presented in Section 5 for point sources and Section 6 for area sources.
Your final report should include:
• Introduction describing the purpose for the inventory development;
• Executive summary of the inventory results;
• Base year of the inventory;
• Geographic area;
• Summary of the emissions data, presented in a matrix format to include pollutant,
source, and geographic area;
• Procedures used to collect the data;
• Sources of data, including citations for all emission factors and activity data;
• Methods used to calculate emissions, including example calculations;
• Complete explanation of all assumptions made in the estimation process;
• QA/QC checklists and all audit reports;
• Sample copies of questionnaires, and information concerning the number of
questionnaires sent, the number of responses received, methods for extrapolating
data to account for nonrespondents, and any assumptions made; and
• Identification of sources of emissions not included in the inventory.
Each EPA Regional Office will determine what information must be submitted as hard copy
documentation. You must submit your data to EPA in an electronic form. Use of an appropriate
reporting format, for both hard copy and electronic submissions, is important because it:
• Makes the data easily accessible for review;
• Allows for efficient transfer of information;
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• Makes it simple to share your data with other air pollution control agencies or
interested parties;
• Makes your data easy to compare with data from other sources; and
• Allows the data to be efficiently added to existing databases.
You can submit your data to EPA using one of several data transfer options. The appropriate
data transfer method is identified during the planning stage of the inventory process, based on the
end use of the inventory and availability of resources.
You should keep in mind that information technology is a rapidly changing field, and electronic
reporting of inventory data is an evolving issue. Refer to the EPA Data Submission page at
http:/www.epa.gov/ttn/chief/ei/eisubmit.html for updates on emissions reporting.
Four options are available for data reporting to EPA; refer to Appendix I for a detailed
description of these methods The reporting options are:
• Aerometric Information Retrieval System/Aerometric Information Retrieval
Facility Subsystem (AIRS/AFS);
• NET Input Format;
EIIPEDIX12;and
• Direct Source Reporting.
NOTE: At this time, the NET Input Format and the AIRS/AFS are both viable options for
submitting the point source data, although the NET option is the preferred option because
the emissions component of AIRS/AFS will be phased out by the end of September, 2000,
and the data transferred to the NET format. The NET Input Format is the preferred
option for submitting area source data. You should consult the AIRS/AFS Web site at
http://www.epa.gov/ttn/airs/afs/index.html for the latest memos and information on the plans
to migrate the emissions components of AIRS/AFS to the NET database.
If your agency decides not to use any of these methods, they are still required to submit their data
in electronic form. Your agency can make special arrangements with EPA to submit another
electronic format, but, because of limited resources, EPA may not be able to enter the data into
the EPA system. If your agency does not submit data to EPA in a form it can process, EPA
may generate data to represent the emissions from your area.
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3.19 What Are Emission Projections?
Emission projections are needed to determine if a given area will achieve or exceed the NAAQS
in future years, and to plan compliance strategies. The basic reference for information on
emissions projections is EPA's projection guidance document titled Procedures for Preparing
Emissions Projections (EPA, July 1991). General projection issues for inventories are also
discussed in Volume I of the EIIP series.
The EIJP Projections Committee addresses the needs of local, state, and regional agencies by
providing guidance on options for forecasting future emissions. The Committee examines
alternatives for projecting emissions changes into the future and develops lists of recommended
approaches for applying specific indicators. The EIJP Projections committee technical papers
can be accessed on the World Wide Web at http://www.epa.gov/ttn/chief/eiip/project.htm.
Additional emission projection resources such as the Economic Growth Analysis System
(EGAS) and the Multiple Projection System (MPS) can be accessed on the World Wide Web at
http://www. epa.gov/ttn/chief/eidata. html.
There are two types of emission projections:
• Baseline emissions projections; and
• Control strategy emissions projections.
3.19.1 What Are Baseline Emissions Projections ?
Baseline emissions projections are estimates of future year emissions that take into account:
• Expected growth in an area;
• Existing air pollution control regulations in effect at the time the projections are
made; and
• Promulgated regulations expected to take effect at future intervals
Baseline projections provide a reference point for measuring reasonable further progress (RFP)
and determining if additional emission reductions are necessary to attain the NAAQS.
3.19.2 What Are Control Strategy Emission Projections ?
Control strategy projections are estimates of future year emissions that also include the expected
impact of modified or additional control regulations. Control strategy emission projections are
used because while baseline emissions projections take into account promulgated regulations
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expected to take effect at future intervals, they often do not reflect all of the growth and control
scenarios that the agency may wish to evaluate.
3.20 How Do I Maintain the Emission Inventory?
You must monitor and record changes in the total number of sources as well as changes in
operation of existing sources. During a year, changes can occur that might impact the emissions
inventory. For example:
• Existing facilities could deactivate process equipment or close completely;
• New facilities and/or processes could come online;
• Existing facilities could increase or decrease production schedules;
• Existing facilities could modify their product line;
• Population changes could affect the number and type of area sources;
• Changes in land use patterns could affect the number and type of area sources;
• Changes in regulations could impact the inventory scope; and
• Updates in emission factors or other emission estimation tools could require
recalculation of certain emission estimates.
It is necessary to collect new data and information to calculate emissions to represent current
conditions. Existing inventories should serve as a starting point because they contain extensive
data and support information files. For effective use of resources, you should build upon and
improve the quality of existing data to fulfill inventory requirements. Document these changes
as you become aware of them and update the emission estimates accordingly.
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4.0 QA/QC PROCEDURES FOR EMISSION INVENTORY
PREPARATION
This section presents a general overview of quality assurance (QA) and quality control (QC)
procedures. You should read Volume VI of the EIIP document series for more detail on QA/QC.
If you need information about...
The difference between QA and QC
DQIs
DQOs
QC procedures to follow during inventory
development
QA audits
Errors typically found in emissions
inventories
Completeness checks
Double counting emissions
Then read-
Section 4.1
Section 4.2
Section 4.3
Section 4.4
Section 4.5
Section 4.6
Section 4.7
Section 4.8
4.1 Why Is a QA Program Important?
A comprehensive QA program is essential to the preparation of a reliable, defensible emissions
inventory. A QA program comprises two distinct components:
• Quality Control: A system of routine technical activities implemented by the
inventory development team to measure and control the quality of the inventory as
it is being compiled. QC procedures include technical reviews, accuracy checks,
and the use of approved standardized procedures for emissions calculations.
• Quality Assurance: A system of external review and audit procedures conducted
by personnel not involved in the inventory development process. QA is an
independent, objective review by a third party to assess the effectiveness of the
QC program and the quality, completeness, accuracy, precision, and
representativeness of the inventory.
NOTE: As a member of the inventory preparation team, you will be actively involved in
the QC activities, but will not take part in the QA activities.
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A common shortcoming of many inventory development programs is that inadequate resources
are devoted to QA/QC activities. A general rule of thumb used by many QA professionals is that
10 percent of the allocated resources should be used for QA activities. This does not include the
costs of QC, which are assumed to be built into the process. Too often, QA activities are
concentrated at the end of the inventory process. An effective QA program will include
planning, numerous QC checks during inventory development, and QA audits at strategic points
in the process. It is vital that you obtain the commitment of your management to the quality
program. This will require the commitment of resources to provide training and proper
equipment (e.g., computers) as well as providing sufficient time for the inventory staff to get the
work done.
It is your responsibility to perform the appropriate level of QC and technical review prior
to releasing your inventory to EPA or others. Do not rely on the recipient or end users of
the inventory to perform the QC checks that are your responsibility.
Although the QA/QC process can take significant time and effort, it will save you time in the
long run by reducing invalid results. In addition, a thorough QA/QC system ensures confidence
in the inventory.
4.2 What are DQIs?
DQIs, data quality indicators, are qualitative and quantitative descriptors used to interpret the
degree of acceptability or utility of the data. The principal DQIs are:
• Accuracy: The closeness of a measurement to the true value, or the degree of
agreement between an observed value and an accepted reference value. Accuracy
includes a combination of error (precision) and systematic error (bias) that are due
to sampling and analytical operations;
• Comparability: The degree to which different methods, data sets, or decisions
agree or can be represented as similar;
• Completeness: The amount of valid data obtained compared to the planned
amount; and
• Representativeness: Degree to which an inventory is representative of the region
and sources it is meant to cover.
Refer to EIIP Volume VI for additional information about DQIs.
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4.3 What Are DQOs?
DQOs, data quality objectives, are qualitative and quantitative statements to identify the level of
uncertainty that a decision-maker is willing to accept. The purpose of DQOs is to ensure that the
final data will be sufficient for the intended use.
DQOs are identified as part of the inventory planning process. They are determined based on the
end use of the inventory, but should realistically reflect the limitations resulting from time
constraints, resource (staff and funding) limitations, and lack of data. A statement of DQOs
should be prepared as part of the inventory preparation plan.
NOTE: Your task manager is responsible for defining the DQOs for the inventory. Your
responsibility as the inventory preparer is to make sure your results meet the agreed upon
DQOs.
The development of a DQO statement is an iterative process. The managers must work together
to balance the quality objectives and the available resources. It is important to acknowledge the
constraints that limit the ultimate quality of the inventory, especially if the achievable DQOs fall
short of the desired DQOs.
Refer to EIIP Volume VI for additional information about DQOs.
4.4 What Quality Control Procedures Should I Follow?
You should follow prescribed QC procedures while inputting and manipulating data. You should
also conduct some of the technical reviews and accuracy checks listed in Table 4-1. These
procedures are briefly described below. Carefully review the QA/QC portion of your inventory
preparation plan to identify the QC activities you are responsible for.
Quality control is best implemented through the use of standardized checklists that assess the
adequacy of the data and procedures at various intervals in the inventory development process.
The EIIP series of documents addresses QC procedures and provides detailed checklists to assist
you. You should refer to Section 7, Quality Assurance/Quality Control, in Chapter 1,
Introduction to Stationary Point Source Emission Inventory Development, and to Volume VI of
the EIIP series for detailed instructions on how to perform QC checks on your inventory.
Specifically, you should use QC checklists to monitor the following procedures and tasks:
• Data collection;
• Data calculations;
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Table 4-1.
Primary QA/QC Functions Of General Types Of Methods
Method
Ensure Ensure Ensure Proper Assess
Reasonableness Validity of Ensure Ensure Optimize Implementation Accuracy
of Emissions, Assumptions, Mathematical Valid Data QA/QC of QA/QC of
Data Methods Correctness Were Used Efforts Program Estimates
Reality checks S
Peer review S S S S S
Sample / / S
calculations
Computerized
checks
/ / / /
Sensitivity S S
analysis
Statistical checks
Independent
audits
/ /
/ / / / / /
Emissions S S S
estimation
validation
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• Evaluation of data reasonableness;
• Evaluation of data completeness;
• Data coding and recording; and
• Data tracking.
Checklists can assist you in finalizing the inventory prior to submitting it to a reviewing agency
(e.g., EPA). The checklist includes questions concerning completeness, use of approved
procedures, and reasonableness An example QC checklist is included in Appendix N.
Since most, if not all, of the emission calculations activities are performed electronically, rather
than manually, it is critical that the spreadsheets used to generate the emission estimates be
checked for accuracy. Appendix N provides procedures for developing, documenting, and
evaluating the data in spreadsheets.
4.4.1 What Is a Reality Check?
The reality check is the most commonly used QA/QC method and is used to catch large errors
early in the estimation process. This check is in the form of the questions "Is this number
reasonable?" or "Does this number make sense?" You should never use the reality check as
the sole criterion of quality. Each reviewer should carefully document the results of the reality
check, using standardized forms or report formats, when applicable.
When using the reality check as a QC check of the data, you must keep in mind:
• In order to answer the reality check questions with confidence, the reviewer must
have a sound understanding of what is reasonable for the value being estimated;
• An estimate can appear to be reasonable, and be incorrect;
• An estimate can appear to be not reasonable, and be correct; and
• This method does not yield any information about the source of the error.
Table 4-2 summarizes the EIIP preferred and alternative methods for performing reality checks.
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Table 4-2.
Reality Checks: Preferred and Alternative Methods
Method
Preferred
Alternative 1
Alternative 2
Alternative 3
Alternative 4
Procedure
Compare data or estimate to a standard reference value.
Compare data or estimate to a value from a previous or alternative
inventory (or database) for the same region.
Compare data to values used for other regions.
Use expert or engineering judgment to assess the reasonableness of the
values.
Compare estimates for similar categories within the same inventory.
4.4.2 What Is Peer Review and How Does It Benefit the Inventory Process?
Peer review is an independent review of calculations, assumptions, and/or documentation by a
person with a moderate to high level of technical experience. Peer review generally involves
reading or reviewing documentation. Peer review is conducted to ensure that assumptions and
procedures are reasonable, but might not include rigorous certification of data or references.
When using peer review as a QC check of the data, you must keep in mind:
• Peer review is a form of reality check, and therefore has the same limitations;
• For large or complex inventories, it is easy for a peer reviewer to overlook errors.
No specific tools are required to conduct a peer review, but the use of checklists or review forms
is recommended. A checklist ensures that reviewers have a clear understanding of what they are
expected to do. Also, checklists provide an efficient means to document the QC procedure.
Each reviewer should carefully document the results of the peer review, using standardized forms
or report formats, when applicable. Table 4-3 summarizes the EIIP preferred and alternative
methods for performing peer reviews.
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Table 4-3.
Peer Review: Preferred and Alternative Methods
Method
Preferred
Alternative 1
Alternative 2
Procedure
Use of a checklist showing elements to be covered by the review.
Provides a guide for the peer reviewer and can be tailored to fit a
Written comments by reviewer identifying issues noted.
specific
Written notes summarizing reviewer's comments identifying issues noted
by reviewer as told to author of notes.
4.4.3 What Does Replication of Calculations Mean ?
Replication of calculations is the most reliable way to detect computational errors and can be
done by any team member involved in the inventory. Replication of calculations should be
conducted throughout the inventory process by the author of the original calculations as a
self-check, by the team member conducting QC checks, and as part of the QA audit.
When using replication of calculations as a QC check of the data, you must keep in mind:
• Replication of calculations does not check to ensure that the approach and
assumptions are correct;
• Replication of calculations does not involve a check of the accuracy or quality of
the original data; and
• This is a labor-intensive process.
No specific tools are required to conduct replication of calculations, but the use of checklists or
review forms is recommended. A checklist ensures that reviewers have a clear understanding of
what they are expected to do. Also, checklists provide an efficient means to document the QC
procedure. Each reviewer should carefully document the results of the replication of
calculations, using standardized forms or report formats when applicable.
Because replication of calculations is a labor-intensive process, you must follow procedures
presented in the QA/QC portion of the inventory plan to determine the percentage of calculations
to be checked. As a general rule, a minimum often percent of calculations is checked, but this
percentage will vary depending on:
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• The complexity of the calculations;
• The inventory DQOs; and
• The rate of errors encountered in the data that are checked.
Table 4-4 summarizes the EIIP preferred and alternative methods for replication of calculations.
Table 4-4.
Calculation Checks: Preferred and Alternative Methods
Method
Preferred
Alternative 1
Alternative 2
Procedure
Hand replication of one complete set of calculations.
Hand replication of most complex calculations.
Hand calculation using a different method, attempting to
result.
approximate the
4.4.4 What Are Computerized Checks?
Automated data checks can be built-in functions of databases, models, or spreadsheets or can be
designed as stand-alone programs. You can use automated QA/QC functions to facilitate peer
review or, in some cases, replace manual reality checks. Computer-based QC checks can process
large volumes of data quickly, significantly reducing the amount of time needed to compile and
QA an inventory. You can use automated data checks to:
• Check for data format errors. For example, a program can be used to ensure that
characters cannot be entered in a field that requires a numerical value;
• Conduct range checks to ensure that data falls within a specified minimum and
maximum range; or
• Provide look-up tables to define permissible entries.
When using automated data checks as a QC check of the data, you must keep in mind:
• Human reasoning and judgment are necessary to evaluate the data for errors.
Automated data checks are not a substitute for evaluation of the data by an
auditor; they serve as a tool to allow an auditor to evaluate the data efficiently;
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• These checks provide only the information requested. Data not subject to
computerized checks must be evaluated by another means;
• Automated data checks do not check to ensure that the approach and assumptions
are correct;
• Automated data checks do not involve a check of the accuracy or quality of the
original data; and
• Each reviewer should carefully document the results of the review, using
standardized forms or report formats when applicable.
Table 4-5 presents examples of computerized data checks.
4.4.5 What Are Statistical Checks and How Are They Used?
Commonly used statistical methods for QC of an emissions inventory are:
• Descriptive statistics - mean, standard deviation, frequency distributions. These
are used to summarize the data set and facilitate peer review;
• Statistical procedures to identify outliers; and
• Statistical tests, such at the t-test, can be used for comparability checks, for data
validation, or to evaluate the relationships between parameters used in an
inventory.
Statistical procedures can be used as tools to facilitate reality checks, peer reviews, and
independent audits. They can be used to compare results or to identify unusual or unlikely
values. Statistical data checks can process large amounts of data and reduce the subjectivity of
informal reality checks. Refer to EIIP Volume VI for additional information.
When using statistical methods for QC checks of the data, you must keep in mind:
• Human reasoning and judgment are necessary to evaluate the data for errors.
Statistical analyses are not a substitute for evaluation of the data by an auditor;
they serve as a tool to allow an auditor to evaluate the data efficiently;
• Common statistical methods are based on the assumptions of normality.
Emissions data are often not normally distributed;
• Statistical data checks do not check to ensure that the approach and assumptions
are correct;
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Table 4-5.
Summary of Common Automated Checks
Type of
Automated Check
Description
Examples
Strengths/Limitations
Variable type check
Alerts user if wrong data
type or inappropriate
value is entered.
Numeric value is expected, character
string entered: a warning is issued
immediately or field is flagged in
subsequent report.
Reduces errors early in process, especially if
warning issued interactively and/or if incorrect data
entry prohibited.
Report in which error is flagged is easily ignored.
Range (value)
checks
Checks value entered to
determine if it is within
an expected or
acceptable range.
Range of stack heights is used to flag a
stack height that is too high or low.
Flags suspicious data for further review.
Does not eliminate possibility that wrong value
entered is within range, or that value outside range
could still be correct.
Look-up table
Uses a parameter (such
as user-supplied input
variable) to select other
appropriate parameters
from a table.
User enters a source category code
(SCC) and program supplies appropriate
emission factor.
Eliminates some types of data entry errors; assures
data consistency.
If wrong value added (i.e., incorrect SCC), all
dependent values will also be wrong.
Pull-down menu,
pop-up window
Presents selection of
possible values for a
particular field.
List of possible fuel types is presented
to user when entering data to calculate
boiler emissions.
Eliminates transcription errors, reduces chance of
using wrong value due to user not understanding
what is wanted.
Does not eliminate possibility that wrong choice
will be made by user.
Completeness/
Consistency checks
These two terms are
often used to describe
similar operations;
include a wide array of
checks and/or
comparisons.
Checks verify that some specified
amount of data for certain fields has
been entered; or, if a certain field has
data, verifies that other required fields
also have data.
Assure that units, equipment types, IDs,
and other parameters are consistent.
Completeness is often difficult to quantify; in
practice, a minimum expected value is used to
determine completeness.
Does not assure that data are correct.
Impossible to completely automate these types of
checks, some expert judgment usually required. If
too much consistency automated into process,
inflexibility may result.
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• Statistical data checks do not involve a check of the accuracy or quality of the
original data; and
• Each reviewer should carefully document the results of the review, using
standardized forms or report formats when applicable.
4.5 How Will Quality Assurance Audits Benefit the Emission Inventory Process?
Independent audits (QA audits) involve a systematic evaluation of the emission inventory
preparation process. They are a managerial tool to evaluate how effectively the emissions
inventory team complies with predetermined specifications for developing an accurate and
complete inventory. QA audits are conducted to determine whether QC procedures in place are
effective, are being followed, and if additional QC is necessary to the inventory development
process.
Because QA audits are conducted by personnel outside of the emissions inventory team, you will
not be involved in this process. You should be prepared to fully cooperate with any auditor who
requests information or documentation.
Specifically, QA audits are managerial tools used to:
• Identify staffing issues such as understaffmg, or inadequate training of staff;
• Evaluate the effectiveness of the technical and quality procedures used to
develop the emissions data;
• Provide confidence in the accuracy and completeness of the emissions data;
• Determine if DQOs are being met;
• Identify the need for additional QC measures; and
• Streamline the costs associated with the inventory development.
4.6 What Types of Errors Are Typically Found in an Emissions Inventory?
Errors commonly found in emissions inventories include:
• Missing facilities;
• Duplicate facilities: name changes through corporate acquisitions;
• Improper facility location data;
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• Missing operating or technical data;
• Erroneous technical data: misinterpretation of data or transcription errors;
• Inconsistent point and area source size designation: failure to designate
inventory size cutoffs;
• Errors in calculations: transposition of digits; decimal errors; entering wrong
numbers; misinterpreting emission factor applications; and
• Data entry and transposition errors; data coding errors.
The QA/QC activities outlined in the inventory preparation plan should address how to avoid
these errors, and how to make corrections to the inventory when these errors are found.
4.7 How Do I Identify and Fill Data Gaps?
Data gaps in the inventory may be the result of:
• Pollutants unaccounted for due to a lack of credible emission factors;
• Facilities that are missing or unaccounted for due to incomplete source lists; and
• Source categories that have not been considered due to a lack of credible
emission factors or activity data.
Filling data gaps is done on a case-by-case basis and depends on the nature of the data gap and
the importance of the source category under review. You should prioritize your gap filling effort.
Tools available for gap filling include:
• Performing additional searches of databases to identify appropriate surrogate
activity data and emission factors;
• Using the NET database to spatially allocate emissions to the area of study;
• Extrapolating emissions from other geographic areas; and
• Projecting emissions data from past inventories within the same geographic area.
You must carefully document your gap filling actions, including all assumptions made and all
resources used.
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Data quality issues may surface when filling data gaps. For example, you might derive emissions
from a certain source category by projecting emissions from previous national inventories based
upon growth indicators. These emissions estimates may not adequately capture facility
shutdowns, new facilities, changes in operations relative to the previous inventory levels, or
additions of new controls. Thus, while there are emission estimates available for gap filling, the
data quality will not be of the same level as the emission estimates developed using actual and
current data. You should discuss this tradeoff between accuracy and completeness with your task
manager before you make a decision on gap filling strategy.
You can check for completeness by manually comparing your inventory with the lists of
pollutants and source categories shown in Appendices J, K, and L You can also check
existing inventories and permit files by source category to ensure that all source types were
included. Volume VI of the EHP document series addresses completeness checks and should be
consulted for more information.
4.8 What Is Double Counting and How Do I Avoid It?
Double counting occurs when the emissions from one source are included twice in the same
inventory. Double counting can result from:
• Overlap between point and area sources: For example, emissions from large dry
cleaning facilities (above the threshold for point sources) are included in the
point source inventory. If you do not take steps to ensure that these emissions are
not included in the area source inventory for dry cleaning facilities, the emissions
will be counted twice. Inventory preparers should compare the lists of point and
area emission sources to see if any sources have been included in both
inventories. If the emissions from a process at a facility have been included in
both the point and area source inventories, then the area source inventory must be
adjusted downward to avoid double counting the emissions. Examples of area
sources that may overlap with point sources are listed in EIIP Volume HI. A list
of sources you should evaluate for double counting resulting from point and area
source overlap is presented in Table 4-6.
• Overlap between area source categories: For example, when compiling an
emission estimate for the prescribed burning area source category, you must be
careful not to include emissions from agricultural burning. To avoid this type of
double counting, you must become very familiar with the definitions of each area
source category and understand the processes. The chapters in EIIP Volume HI
provide source categorization information and advise you when to be alert for
possible double counting.
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Table 4-6.
Source Categories That May Have Area and Point Source Contributionsa
Process
Category Examples
Fuel Combustion
Electric Utilities
Industrial Fuel Combustion
Commercial Fuel Combustion
Industrial Processes
Chemicals and Allied Products
Metals Production
Rubber and Plastics
Oil and Gas Production
Mineral Processes, Mining and Quarrying
Construction/Demolition
Machinery
Petroleum Refining
Solvent Utilization
Graphic Arts
Surface Coating
Dry Cleaning
Degreasing
Storage and Transport
Petroleum and Petroleum Product Storage and
Transport
Organic Chemical Storage and Transport
Rail and Tank Car Cleaning
Waste Disposal and Recycling
Wastewater Treatment
Treatment, Storage and Disposal Facilities (TSDFs)
Scrap and Waste Materials
Landfills
Miscellaneous Sources
Cooling Towers
Firefighting Training
Engine Testing
a Common examples based on AIRS source codes are listed. Almost any source category could include
point sources. Coordination between point and area source inventory preparers is required to insure that
all sources are properly accounted for and that emissions are not double counted.
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In each of these cases, care to prevent double counting must be taken during the area source
inventory process. When area sources overlap with point sources, the area source inventory
must be adjusted downward by subtracting out the emissions contributions from the major
sources.
Use this equation to adjust area source inventories for point source contributions:
Area Source Activity = Total Activity of Source Category - Sum of Point Source Activity
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5.0 POINT SOURCE INVENTORIES OF CRITERIA POLLUTANTS
This section describes issues relevant only to point sources.
If you need information about...
What emission sources to include in the
inventory
Level of detail of inventories
Special issues to consider during
inventory development
Emissions estimation methods
Temporal allocation of emissions
Then read-
Sections 5.1 and 5.2
Sections 5.3
Section 5.4
Section 5.5
Section 5.6
5.1 What Sources Should Be Included?
The pollutants to be inventoried must be determined before the relevant source categories can
be identified and prioritized. The pollutants of interest for ozone precursor inventories are
VOC, NOX, and CO. If needed, it is efficient to inventory pollutants such as SO2, PM, Pb, and
CO at the same time.
After you identify the pollutants to be inventoried, you will need to identify the source
categories to be included in the emissions inventory. The number and types of the sources to
be included is generally determined by the regulations driving the need for the inventory. For
example, a SIP inventory requires that point, area, mobile, and biogenic sources be inventoried
and a very thorough accounting of sources within each of these groups is expected. It is
important that the inventory planners specify clearly which sources are to be included.
EPA has published several documents containing general guidance for compiling emissions
inventories:
EIIP Volumes I through VHI;
• Procedures for the Preparation of Emission Inventories for Carbon Monoxide
and Precursors of Ozone, Volume I: General Guidance for Stationary Sources
(EPA, May 1991);
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• Emissions Inventory Guidance for Implementation of Ozone and Paniculate
Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze
Regulations (EPA, April 1999b); and
• EPA publishes annual estimates of national emissions from criteria air pollutants
for over 450 individual source categories that include all major sources of
anthropogenic emissions (EPA, December 1998).
Through all these documents, EPA identifies numerous source categories for point and area
sources. These references are good starting points for developing a list of source categories in
the inventory area. Note however, that not all the sources listed in these documents may be
operating in your inventory area. Since the source category coverage is driven by the pollutants
of interest, you should research possible sources for the particular pollutants and determine if
any are operating in the inventory area.
You should also be aware that while some source categories (such as electric utilities) are
usually treated as point sources, others (such as dry cleaners and service stations) can be either
point or area sources depending on the size of the operation and the corresponding emission
levels. Even within a point source facility, some activities occur that are more easily treated as
area source emissions. Some emissions associated with surface coating operations such as
equipment cleaning, for example, can be more practically estimated using area source methods.
Appendix J provides summary tables based on the 1997 National Air Pollutant Emission
Trends Update (EPA, December 1998). These tables present criteria pollutants, by pollutant,
emitted from stationary and natural sources. Appendix J also shows the emissions
contributions of various source categories relative to the overall emissions levels, and relative
to the emissions from each main source category. For example, the CO table in Appendix J
shows that in 1997, 24 percent of the CO emissions from stationary and natural sources were
emitted from fuel combustion sources. The table also shows that electric utilities were
responsible for 8 percent of the CO emitted from fuel combustion sources. Moreover, the CO
table shows that coal-fired boilers at electric utilities resulted in 63 percent of CO emissions
from all electric utilities.
A list of potential point source categories and the associated criteria air pollutants
emitted from each is provided in Appendix K. Appendix K is based on an analysis of EPA's
NET database and is provided to help you focus the point source inventory efforts (EPA,
April 1999b). Appendix K shows where EPA's database indicates that significant point source
emissions occur. The H (high), M (medium), and L (low) designations indicate the level of
significance of the emissions from a source category to the overall emissions of that pollutant.
A "/" indicates that emissions of the pollutant may occur from that category but are not
considered significant. A blank cell indicates that no emissions of the pollutant were recorded
in EPA's NET database for that source category.
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Point sources are typically categorized into the following broad groups:
• Fuel combustion (external combustion boilers, internal combustion engines);
• Waste disposal;
• Food and agriculture industry;
• Metallurgical industry;
• Petroleum-related industries;
• Mineral products industry;
• Chemical process industry;
• Wood products industry; and
• Storage Tanks.
Because the source categories included in the inventory are driven by the pollutants of interest,
you should research possible sources of criteria pollutants and determine if any are operating in
your inventory area. Specifically, you should:
• Research all of the documents and tools made available by EPA, the historical
and current knowledge of your inventory area, and current research publications.
All possible source categories for the given pollutant and inventory type should
be investigated;
• Eliminate any sources that are not found within the inventory area. For
example, in the mineral products industry, hot mix asphalt manufacturing may
not occur in the inventory area;
• Prioritize the list of remaining categories based on the expected magnitude of
emissions or some other measure of importance, such as the purpose of the
inventory, regulated sources, sources under study for future regulations, or
sources of specifically targeted pollutants;
• Consider the time and budget constraints under which you are operating; such
constraints may require that the list of remaining source categories be reduced
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further. Resources should be allocated preferentially to the sources that are
most important for meeting the inventory objectives;
• Eliminate from your source category list any categories for which no emission
factors or acceptable methods have been developed.
• Document your decisions for the benefit of future preparers who may be able to
expand the inventory's coverage or scope.
5.2 How Do I Identify Specific Point Sources in the Inventory Area?
Compiling a list of facilities to be included in the inventory is the first necessary step in
developing an inventory. The list should identify each facility by name, address, size, and SIC.
NOTE: Because the SIC code assigned to a facility denotes the principal economic
activity of the firm, the code may not correspond to the activity contributing to emissions.
Appropriate source classification codes (SCCs) that identify process operations
producing emissions, should be assigned to the facility, as well.
If possible, a facility contact name and phone number of the person responsible for working
with the agency should also be identified in the facility list. You can use the facility list to
determine if the resources allocated for the inventory development effort are sufficient.
Frequently, you will identify more sources during the inventory process than you believed to
exist during the initial planning stages.
As a starting point, you should review the information in Appendices J and K. These include
information relating criteria pollutants to source categories. Your review of these tables will
provide you with a general understanding of which pollutants are likely to be emitted from
which source categories.
Other sources of information that are useful for identifying which point sources to inventory are
as follows:
• NET report/database;
• State and local commerce directories;
• Existing state inventories of criteria pollutants and HAPs. An existing point
source inventory is the best source of information, particularly if it has been
frequently updated and well documented. A list prepared from the existing
inventory will require updating by:
Deleting any point source that has discontinued operation;
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Making appropriate changes for any source that has changed status; and
Adding new point sources.
• Other agency files: Existing registration program of point sources (through
annual inventory submittal programs, permit renewal programs, Risk
Management Plan submittals, and/or upset and malfunction reports) though such
programs usually do not include smaller significant point sources or fugitive
emissions. Also, compliance, enforcement, and permit files are a useful source
of information;
• TRI data for your state, http://www.epa.gov/opptintr/tri/access.htm
• Files of other government agencies (labor, tax, commerce and trade agencies).
State and local industrial directories typically contain companies listed
alphabetically by SIC code and county;
• Standard and Poors, Registration of Corporations;
• Thomas Register;
• Trade and professional societies;
• The Dun andBradstreet Million Dollar Directory listing companies with sales
over $1,000,000 per year by SIC code and county, http://www.dnb.com/; and
• Information regarding industries that are prevalent in the state (the agency may
establish emission cutoff levels to exclude smaller sources from the inventory).
You should be cautious when using HAP inventories or existing registration programs as
sources of information on facilities emitting criteria pollutants. In general, you will be dealing
with the same type of sources in both criteria and HAP inventories because most HAPs are a
subset of either PM or VOC. However, not every source of criteria pollutant emissions will
be included in the HAPs inventory. Moreover, you must not rely solely on existing HAP
inventories for a complete list of sources to be covered in your criteria pollutant
inventory.
5.3 At What Level of Detail Are Point Source Inventories Compiled?
Point source inventories are compiled at differing levels of complexity. The appropriate level
of complexity is determined during the planning phase of the inventory process, based on the
end use of the inventory, data quality objectives, and availability of resources.
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Note: If the inventory is to be used in a regional modeling effort, modelers should be
aware that data must be collected in a consistent manner across the participating states.
Levels of complexity for point source inventories are distinguished by the entity defined as the
emission source:
• Plant level: The emission source is defined as an entire plant or facility;
• Process level: The emission source is defined as a process or operation within a
facility; and
• Unit level: The emission source is defined as a stack, vent, or other unique
point of emission to the ambient air.
• Segment level: The emission source is defined by the operating scenario of a
process or operation within a facility (for example, two or more fuels).
5.4 What Special Issues Should I Consider When Estimating Criteria Pollutant
Emissions from Point Sources?
When compiling an emissions inventory, you should consider the issues presented in Table 5-1.
5.5 What Emissions Estimation Methods Should I Use?
Inventories of point sources are usually approached on a facility-by-facility basis due to the
significance of their emissions. The methods most commonly used in estimating emissions of
criteria pollutants from point sources include:
• Continuous emissions monitor (CEMs);
• Source testing;
• Material balance;
• Emission factors;
• Fuel analysis;
• Emission estimation models (usually software); and
• Engineering judgment.
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Table 5-1.
Issues to Consider When Estimating Criteria Pollutant Emissions from Point Sources
For a point source inventory, you
should...
Because...
Helpful references include...
Carefully consider what source categories to
include in the inventory.
Attempting to inventory all source
categories may overburden an agency's
resources, especially if a majority of the
sources are deemed insignificant
contributors to pollution by the state. A
screening study will help you focus the
inventory effort.
Guidance on how to conduct
screening studies for the
purpose of inventory
development is available in
Appendix L.
Consider threshold levels of emissions for
sources to be included in the inventory.
If the agency does not preclude reporting of
emissions below specific exemption or
de minimis levels, the effect on agency
resources may be similar to that of
inventorying all source categories for all
criteria pollutants.
Consider the differences in the source
defmition(s) for the purposes of criteria and
HAP inventories when using a HAP
inventory as a starting point for the criteria
pollutant inventory.
Some industrial sources with PM or VOC
emissions below typical cutoff levels may
be categorized as area sources for the
purpose of a criteria pollutant inventory, but
may qualify as major point sources for the
purpose of a HAP inventory.
Check the results of any survey for
completeness.
When surveying sources directly, there may
be a need to follow-up with a facility,
particularly if you believe it is emitting a
certain pollutant it does not report.
-------
Table 5-1.
Issues to Consider When Estimating Criteria Pollutant Emissions from Point Sources (Continued)
For a point source inventory, you
should...
Because...
Helpful references include...
Stay informed of air regulations and rule
development activities and implementation
information.
Some MACT standards may also contain
information that addresses emission limits
on criteria pollutants (e.g., a standard may
use PM concentration as a surrogate to
measure non-volatile metals concentration
as part of total HAP reductions).
You can access comprehensive
MACT rule-specific information
including Federal Register
publications and citations,
compliance dates, and MACT
rule contact names and phone
numbers through the UATW site
at http://www.epa.gov/ttn/uatw/
eparules.html.
oo
Keep in mind that nationally-derived
emission factors may not apply directly to
your area and may need to be adjusted.
Emissions calculated using national
emission factors may vary considerably
from actual values at a specific source or
within a specific geographic area.
Avoid double counting of sources and
emissions.
Overlap can occur between point and area
sources.
Section 4.8 of this document and
EIIP Volumes II and IE.
Know your pollutants.
For example, several VOC are considered
photochemically nonreactive by the U.S.
EPA as defined in the CAA and are not
included in VOC emissions inventories (63
FR 17331, April 9, 1998: Part 51 "Air
Quality Revision to Definition of VOC -
Exclusion of Methyl Acetate.").
-------
Table 5-1.
Issues to Consider When Estimating Criteria Pollutant Emissions from Point Sources (Continued)
For a point source inventory, you
should...
Because...
Helpful references include...
Make sure you account for fugitive
emissions. Fugitive emissions are
emissions that are technically infeasible to
collect and control such as emissions from
stockpiles, material handling and transfer
operations, and process leaks.
Fugitive emissions may account for a
substantial portion of actual emissions from
many facilities.
Account for factors influencing emissions
such as process variability and/or equipment
malfunctions and upset conditions.
Variations in emissions due to normal
process variability or abnormal operating
conditions can result in emissions increases
which can be difficult to quantify.
Volume II, Chapter 12, of the
EIIP document series addresses
this topic and should be
reviewed for details on how
control device malfunctions
affect emissions. The document
also provides example
calculations.
-------
It is important for you to select estimation methods and approaches based on the best available
data. You will need to conduct the selection process for each source category and pollutant
being inventoried. The EIIP guidance documents refer to "preferred" and "alternative"
methods for estimating emissions for each source category. Selection of a preferred or
alternative emission estimation procedure takes place in the planning phase of the inventory
development process, and should be documented in the inventory preparation plan.
Inventory planners should consider these factors when choosing a methodology:
• Source category priority;
• Agency resources;
• Data quality objectives;
• Availability of data; and
• Intended use of the inventory.
5.5.1 Continuous Emissions Monitors
Continuous emissions monitors (CEMs) measure and record actual emissions during the time
period the monitor is operating and the data produced can be used to estimate emissions for
different operating periods. CEMs are typically used to measure stack gas concentrations of
NOX, CO2, CO, SO2, and total hydrocarbons (THC). CEMs can either be permanently
installed at a source to generate data 24-hours a day or they can be used for emissions
monitoring during a defined source testing period (e.g., 1 to 4 hours).
Appendix D includes example calculations illustrating the use of CEM data for
estimating emissions from point sources.
5.5.2 Source Tests
Source tests are short-term emission measurements typically taken at a stack or vent. The raw
data contained in source test reports can be used to develop emission factors for each pollutant
and emission source of interest. There are several advantages for using source test data in
emissions inventories:
• Source test data are of great value for obtaining general information on the
characteristics of a particular industry and for obtaining specific information on
pollutants being emitted and control device operational parameters.
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• Although site-specific, source test data can be extrapolated to apply to other
representative emission sources for purposes of calculating emissions.
• Source testing reduces the number of assumptions regarding the applicability of
generalized emission factors, control device efficiencies, operating procedures,
and fuel characteristics. As a result, source testing generally yields more
accurate emission estimates than emission factors or material balance.
However, the use of source test data in emissions inventories may be limited for several
reasons:
• Source testing can be expensive, especially if the cost is compounded by a large
number of processes to be tested; and
• Source testing provides a "snapshot" of emissions from a process. As a result,
uncertainties in source testing emission estimates arise because the process
conditions may change over time while the test results can only reflect the
emission rate and conditions during the test runs.
Two items should be noted when using source test data to calculate emissions:
• Because most source tests are only conducted over several hours or days at
most, adjustments may need to be made when using these data to estimate
emissions over longer time intervals. Emission data from a one-time source
test can be extrapolated to estimate annual emissions only if the process stream
does not vary and if the process and control devices are operated uniformly.
Refer to the example calculations in Appendix D
• A source test may not adequately describe a given facility's annual or seasonal
operating pattern. For example, there may be variations in process operation
throughout the year or the efficiency of control device performance may vary
due to fluctuations in ambient temperature or humidity. In such cases, multiple
tests must be conducted for source testing to be useful in generating an
emission estimate for extended periods that are longer than the test period.
Source test reports usually summarize emissions for each pollutant by expressing them in
terms of:
• Mass loading rate: Weight of pollutant emitted per unit time;
• Emission factor: Weight of pollutant emitted per unit of process activity; or
5-11
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• Flue gas concentration: Weight or number of moles of pollutant per weight or
volume of flue gas.
Generally, when a mass loading rate or emission factor is provided in a test report, the
resulting emission estimates can be easily calculated by multiplying the mass loading rate by
the total hours of operation or by multiplying the emission factor by the throughput.
(Throughput is a measure of output or production over a period of time). However, if the
report provides a flue gas concentration, the emissions calculations are more detailed.
Appendix D includes example calculations illustrating the use of source testing data for
estimating emissions from point sources.
EPA has developed reference and equivalent methods for measuring emissions of PM, SO2,
NOX, CO, Pb, and VOC. The reference methods are published in Title 40, Code of
Federal Regulations, Part 60, Appendix A. The Emission Measurement Technical
Information Center (EMTIC) provides technical guidance on stationary source emission
testing.
5.5.3 Material Balance
When you use material balance, you will determine emissions by knowing the amount of a
certain material that enters a process, the amount that leaves the process by all routes, and the
amount shipped as part of the product itself. The simplest method of material balance is to
assume that all solvent consumed by a source process will evaporate during the process.
The material balance method:
• Can be used where source test data, emission factors, or other developed
methods are not available;
• Is most appropriate to use in cases where accurate measurements can be made
of all process parameters except the air emission component;
• Is particularly useful for processes like solvent degreasing operations, and
surface coating operations.
• Is equally applicable to point and area sources.
• Should not be used for processes where material reacts to form secondary
products or where the material otherwise undergoes significant chemical
changes.
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The basic emission estimation equation for mass balance is:
Ex = (Qin - Qout) X Cx
where:
Ex = total emissions for pollutant x
Qin = quantity of material entering the process
Qout = quantity of material leaving the process as waste, recovered, or in product
Cx = concentration of pollutant x in the material.
The term Qout could involve several different "fates" for an individual pollutant. This could
include the amount recovered (or recycled) or the amount leaving the process in the product
or waste stream.
If a material balance method is used to estimate emissions and if the actual emissions are a
small fraction of the throughput, the throughput estimate or measurement can be even more
critical. For example, applying material balances to petroleum product storage tanks is not
generally feasible because the losses are too small to quantify using a metering device. In
these cases, AP-42 or equations or TANKS can be used.
Because the emissions are estimated to be the difference between the material input and the
known material output, a small percentage error in estimating the input or output can result in
a much larger percentage error in the emission estimate. For this reason, material balances are
sometimes inappropriate for estimating relatively small losses.
Appendix D includes example calculations illustrating the use of material balance.
5.5.4 Emission Factors
Emission factors allow the development of generalized estimates of typical emissions from
source categories or individual sources within a category. Emission factors, used extensively
in point source inventories, estimate the rate at which a pollutant is released to the atmosphere
as a result of some process activity. For example, the emission factor for NOX emissions from
the combustion of anthracite coal is 9 pounds of NOX per 1 ton of coal burned (9 Ib/ton). If
you know the emission factor and the corresponding activity level for a process, you can
estimate the emissions. In most cases, emission factors are expressed simply as a single
number, with the underlying assumption that a linear relationship exists between emissions
and the specified activity level over the probable range of application. The use of emission
factors is straightforward when the relationship between process data and emissions is direct
and relatively uncomplicated. Note, however, that emission factors may be developed
assuming no control device is in place. These are referred to as "uncontrolled emission
5-13
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factors." When emission factors are derived from data that was obtained from facilities with a
control device in place, then emission factors are referred to as "controlled emission factors."
While the emissions calculated using emission factors may differ from actual emissions for a
specific facility, emission factors nevertheless provide a reasonable estimate of pollutant
emissions across an entire source category. Because emission factors are typically averages
obtained from data with wide ranges and varying degrees of accuracy, emissions calculated
this way for a given source are likely to indicate higher than actual emissions for some sources
and lower than actual emissions for others.
When the information used to develop an emission factor is based on national data, such as a
wide range of source tests or national consumption estimates, you should be aware of potential
local variations. Emissions calculated using national emission factors may vary considerably
from actual values at a specific source or within a specific geographic area.
National emission factors should be used when:
• No locally derived factor exists;
• The local mix of individual sources in the category is similar to the national
average; and
• The source is a low priority in the inventory.
Locally derived emission factors are preferred when:
• A national level emission factor does not account for local variations; and
• The category is a high priority in the area.
Locally derived emission factors are developed based on:
• Local surveys or measurements;
• Local consumption data; and
• Adaptation of emission information in permits or another inventory.
Typically, the information gathering necessary for developing a local emission factor can be
significant, but the benefits are that the emissions for the source will be well-characterized,
and the emission factor or the information used to develop it can be used in subsequent
inventories.
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If you use factors to predict emissions from new or proposed sources, you should review the
latest literature and technology to determine whether such sources would likely exhibit
emission characteristics different from those sources from which the emission factors were
derived.
Emission factors are usually expressed as the weight of pollutant divided by a unit weight,
volume, distance, or duration of the activity emitting the pollutant. To calculate emissions
using emission factors, four basic inputs to the estimation algorithm are required:
• Activity information for the process as specified by the relevant emission factor;
• An emission factor to translate activity information into uncontrolled or
controlled emission estimates;
• Rule effectiveness factor; and
• When applicable, information on capture and control efficiencies of any control
device when using an "uncontrolled" emission factor.
The basic
where:
E
A
EF
C
RE
emission estimation equation when using an uncontrolled emission factor is:
E = AxEFx(l -CxRE)
= emission estimate for the process
= activity level such as throughput
= emission factor assuming no control
= capture efficiency x control efficiency (expressed in percent); C equals
zero if no control device is in place
= rule effectiveness, an adjustment to C to account for failures and
uncertainties that affect the actual performance of control.
The basic
where:
E
A
EF
RE
emission estimation equation when using a controlled emission factor is:
E = A x EF x RE
= emission estimate for the process
= activity level such as throughput
= "controlled" emission factor
= rule effectiveness
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5.5.5 Fuel Analysis
Fuel analysis can be used to predict emissions based on the application of conservation laws.
The presence of certain elements in fuels may be used to predict their presence in emission
streams. This includes elements such as sulfur which may be converted to SO2 during the
combustion process.
The basic equation used in fuel analysis emission calculations is:
E = Qf x Pollutant concentration in fuel x (MW /MWf)
where:
Qf = throughput of the fuel, mass rate (e.g., Ib/hr)
MW = molecular weight of pollutant emitted (Ib/lb-mole)
= molecular weight of pollutant in fuel (Ib/lb-mole)
Appendix D includes an example calculation illustrating the use of the fuel analysis
equation in estimating SO2 emissions.
5.5.6 Emission Estimation Models
You can use emission models to estimate emissions in cases where:
• The calculations are very complex; and
• A combination of parameters has been identified that affect emissions, but
individually, do not provide a direct correlation.
Some of the available emission estimation models are based on measured or empirical values.
Models often use computers, so that a large number of equations and interactions can be easily
manipulated and the effect of many different parameters can be accounted for. The most
widely used emission estimation models are listed in Section 3.8.4 and described in detail
in Appendix G.
Additional emission estimation models are described in the various chapters of the EIIP series.
Specifically, Chapter 5 of Volume II of the EIIP series describes additional models for
estimating air emissions from wastewater collection and treatment systems. Chapter 10 of
Volume n describes programs available for estimating emissions from oil and gas field
processing operations.
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NOTE: If you choose to use a non-EPA model to estimate emissions, you should do a
thorough evaluation of that model/software and you should get prior approval from
your EPA Regional Office.
5.5.7 Engineering Judgment
You should consider "engineering judgment" to be a last resort to be used only if none of the
methods described above can be used to generate accurate emission estimates. Engineering
judgment may involve the application of speculative or innovative ideas, a poorly documented
emission factor, or a crude material balance. In cases where no emission factors are available
but adverse risk is low, it may be acceptable to apply factors from a similar source category
using engineering judgment.
5.6 Is Temporal Allocation Necessary for Point Source Inventories?
5.6.1 What Is Temporal Allocation?
Temporal adjustments are made because of seasonal differences in the rate of emissions or
high activity, or to apportion emissions to a particular season or day. For example, high
photochemical ozone levels are generally associated with the warmer months of the year,
while CO emission levels are generally associated with the colder months of the year. For air
quality planning purposes, ozone precursor emissions should be determined during the months
constituting the ozone season for ozone inventories. Peak ozone season for most areas of the
United States is May through September. Likewise, the CO emissions inventory should
reflect the conditions when peak CO air quality conditions occur. For many, but not all areas
of the country, the peak CO season will be in the winter months (December through
February). Regional air quality modeling efforts may require hourly emission rates.
You may need to adjust your emissions estimates to account for temporal differences in:
• Activity level: The level of activity of some area sources varies throughout the
calendar year. Some industrial activities are conducted only five days per
week. Some operations, such as architectural surface coating, are more active
in Spring through Fall, because of the warmer temperatures and the increased
number of daylight hours. Other sources, such as residential heating, are active
only in the colder months.
• Rate of emissions: Seasonal variations in temperature can impact the rate of
emissions, even for sources that maintain constant activity levels. For
example, at petroleum product handling and storage operations, breathing
losses from fixed-roof tanks are significantly influenced by changes in the
temperature of the product.
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5.6.2 How Do I Make Temporal Adjustments'!
Emission estimates or activity data for point sources are often presented as a rate per unit time
(e.g., pounds per hour or tons per year). You may need to adjust these data to apportion the
emissions over time for the inventory period. You can use source-specific data for annual or
daily hours of operation to apportion emission estimates and to scale up or down as needed.
Default temporal profiles (i.e., hours/day, days/week, weeks/year) are often used to develop
hourly estimates from annual estimates. Temporal allocation factor files are available in a text
file or a Microsoft Access database file from EPA's Emissions Characterization and
Prevention Branch, RTF, NC (919-541-4593).
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6.0 AREA SOURCE INVENTORIES OF CRITERIA POLLUTANTS
This section describes issues relevant only to area sources.
If you need information about...
What emission sources to include in the
inventory
Level of detail of inventories
Special issues to consider during inventory
development
Emissions estimation methods
Temporal allocation of emissions
Then read...
Sections 6.1 and 6.2
Section 6.3
Section 6.4
Section 6.5
Section 6.6
6.1 What Sources Should Be Included?
The pollutants to be inventoried must be determined before the relevant source categories can
be identified and prioritized. The type of pollutant(s) to be covered in the inventory depends on
the purpose of the inventory. For example, the pollutants of interest for ozone precursor
inventories are VOC, NOX, and CO. If needed, it is efficient to inventory pollutants such as
SO2, PM, Pb, and CO at the same time.
An area source inventory enables the agency to estimate emissions collectively for those
sources that release small amounts of a given pollutant and/or are too numerous to be
inventoried individually as part of the point source inventory. While most stationary sources of
NOX, CO, and SO2 are associated with combustion processes and considered point sources,
VOC and PM sources are generally relatively low emitters (i.e., fall below the threshold for
point sources) and are treated as area sources. VOC emissions are usually associated with
solvent use, and PM emissions are associated mostly with combustion sources and fugitive dust
from unpaved roads and other sources.
You should also keep in mind that some source categories (such as forest wildfires and
pesticide application), are almost always treated as area sources. Others, such as dry cleaners
and service stations, can be either point or area sources depending on the size of the operation
and the corresponding emission levels. When a point source inventory and an area source
inventory estimate emissions from the same process, there is the possibility that emissions
could be double counted. You may need to adjust the area source inventory to avoid double
counting. The approach to correct for double counting is described in Section 4.8 of this
document.
6-1
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Appendix J provides summary tables based on the 1997 National Air Pollutant Emission
Trends Update (EPA, December 1998). These tables present criteria pollutants, by pollutant,
emitted from stationary and natural sources. Appendix J also shows the emissions
contributions of various source categories relative to the overall emissions levels, and relative
to the emissions from each main source category group. For example, the VOC table in
Appendix J shows that in 1997, 85 percent of the VOC emissions from stationary and natural
sources were emitted from industrial processes. The table also shows that solvent utilization
was responsible for 66 percent of the VOC emitted from industrial processes. Moreover, the
VOC table shows that degreasing operations resulted in 11 percent of VOC emissions from all
solvent utilization.
A list of potential area source categories and the associated criteria air pollutants emitted
from each is provided in Appendix L. Appendix L is based on an analysis of EPA's NET
database and is provided to help you in focusing your area source inventory efforts (EPA, April
1999b). Appendix L shows where EPA's database indicates that significant area source
emissions occur. The H (high), M (medium), and L (low) designations indicate the level of
significance of the emissions from a source category to the overall emissions of that pollutant.
A "/" indicates that emissions of the pollutant may occur from that category but are not
considered significant. A blank cell indicates that no emissions of the pollutant were recorded
in EPA's NET database for that source category.
Area sources are typically categorized into the following broad groups:
• Fuel combustion;
• Chemical and allied products manufacturing;
• Metal processing;
• Petroleum and related industries;
• Other industrial processes;
• Solvent utilization (e.g., surface coating, dry cleaning, degreasing, and graphic
arts);
• Storage and transport;
• Waste disposal and transport;
• Natural sources (e.g., wind erosion); and
• Miscellaneous sources (e.g., unpaved roads and agricultural burning).
6-2
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Each of the broad groups of processes contains a number of more specific groups that share
similar emission processes and emission estimation methods.
The importance of area source categories may vary for different areas. Some of the area
sources listed in Appendix L may not exist in a given area; others may be prohibited by
regulation; and some area source categories in your inventory area may be missing from
Appendix L.
Because the source categories included in the inventory are driven by the pollutants of interest,
you should research possible sources of criteria pollutants and determine if any are operating in
your inventory area. Specifically, you should:
• First review existing inventories for your area;
• Research all of the documents and tools made available by EPA, the historical
and current knowledge of your inventory area, and current research publications.
All possible source categories for the given pollutant and inventory type should
be investigated;
• Eliminate any sources that are not found within the inventory area. For
example, aviation gasoline distribution and open burning of scrap tires may not
occur in the inventory area;
Prioritize the list of remaining categories based on the expected magnitude of
emissions or some other measure of importance, such as the purpose of the
inventory, regulated sources, sources under study for future regulations, or
sources of specifically-targeted pollutants;
• Consider the time and budget constraints under which you are operating; such
constraints may require that the list of remaining source categories be reduced
further. Resources should be allocated preferentially to the sources that are
most important for meeting the inventory objectives;
• Eliminate from your source category list any categories for which no emission
factors or acceptable methods have been developed.
• Document your decisions for the benefit of future preparers who may be able to
expand the inventory's coverage or scope.
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6.2 How Do I Identify Area Sources in the Inventory Area?
To compile an area source inventory, you will need to identify two different types of sources:
• Facilities, or activities within facilities, that emit levels of criteria pollutants
below the threshold level for point sources: Such facilities include dry cleaners
and segments of the graphics arts industry.
• Activities that result in emissions of criteria pollutants below the threshold level
for point sources: You will need to consider a diverse group of activities
including surface coating, pesticide application, solvent use, asphalt use,
agricultural burning, construction, residential wood combustion, and livestock
production.
As a starting point, you should review the information in Appendices J and L These
include information relating criteria pollutants to source categories. Your review of these
tables will provide you with a general understanding of which pollutants are likely to be
emitted from which source categories.
Compiling a list of source categories to be included in the inventory is the first necessary step
in developing an inventory. Sources of information other than Appendices J and L that are
useful for identifying which source categories to inventory are:
• Existing state/local inventories of criteria pollutants and HAPs. An existing
area source inventory is the best source of information, particularly if it has been
frequently updated and well documented. A list prepared from the existing
inventory will require updating by:
- Deleting any area source that has discontinued operation;
- Making appropriate changes for any source that has changed status; and
- Adding new area sources.
• TRI data for your state, http://www.epa.gov/opptintr/tri/access.htm;
You should be cautious when using HAP inventories or existing registration programs as
sources of information on facilities emitting criteria pollutants. In general, you will be dealing
with the same type of sources in both criteria and HAP inventories because most HAPs are a
subset of either PM or VOC. However, not every source of criteria pollutant emissions will
be included in the HAPs inventory. Moreover, you must not rely solely on existing HAP
inventories for a complete list of sources to be covered in your criteria pollutant
inventory.
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6.3 At What Level of Detail Are Area Source Inventories Compiled?
Area source emissions inventories are compiled at differing levels of detail. The appropriate
level of complexity is determined during the planning phase of the inventory process, based on
the end use of the inventory, data quality objectives, and availability of resources.
Note: If the inventory is to be used in a regional modeling effort, modelers should be
aware that data must be collected in a consistent manner across the participating states.
Levels of complexity for area source inventories are distinguished by the geographic area used
for the inventory:
• Air quality control region (AQCR) level: AQCRs correspond to high pollution
urban areas defined in 40 CFR. The boundaries of AQCRs tend to coincide
with those of counties or states, but AQCRs can be either interstate or intrastate.
• County level: Much of the data necessary to compile an inventory is collected
on a countywide basis, providing an excellent foundation for the inventory
process.
• Grid level: The Universal Transverse Mercator (UTM) coordinate system is
commonly used to impose uniform grid zones onto geographic areas to permit
the allocation of county level activity and emission data to grid levels. Grid
level inventories are conducted for specific end uses, such as dispersion
modeling, when fine geographical resolution is required.
6.4 What Special Issues Should I Consider When Estimating Criteria Pollutant
Emissions from Area Sources?
When compiling an emissions inventory, you should consider the issues presented in Table 6-1.
6.5 What Emissions Estimation Methods Should I Use?
It is important for you to select the estimation methods and approaches based on the best
available data. This selection should be done for each source category and pollutant being
inventoried. Ideally, all stationary sources would be considered point sources and inventoried
using a bottom-up approach and by applying the various techniques described in Section 5.0 of
this document. However, given the nature of area sources, applying a bottom-up approach to
all area source categories would require resources that are beyond the capabilities of most
agencies.
6-5
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Table 6-1.
Issues to Consider When Estimating Criteria Pollutant Emissions From Area Sources
For an area source inventory, you
should...
Because...
Helpful references include...
Carefully consider what source categories to
include in the inventory.
Attempting to inventory all source
categories may overburden your agency
resources. A screening study will help ]
focus the inventory effort.
you
Guidance on how to conduct
screening studies for the
purpose of inventory
development is available in
Appendix M.
Oi
Consider threshold levels of emissions for
sources to be included in the point source
inventory.
The point source definition used by your
agency may impact which area source
categories you need to include in your
inventory and which area source categories
will need to be adjusted for double
counting.
Section 2.5 of this document.
Consider the differences in the source
defmition(s) for the purposes of criteria and
HAP inventories when using a HAP
inventory as a starting point for the criteria
pollutant inventory.
Some industrial sources with PM or VOC
emissions below typical cutoff levels may
be categorized as area sources for the
purpose of a criteria pollutant inventory, but
may qualify as point sources for the purpose
of a HAP inventory.
-------
Table 6-1.
Issues to Consider When Estimating Criteria Pollutant Emissions From Area Sources (Continued)
For an area source inventory, you
should...
Because...
Helpful references include...
Stay informed of air regulations and rule
development activities and implementation
information.
In addition to adjustments you make for rule
effectiveness (RE) and rule penetration
(RP), some MACT standards may impact
criteria pollutant emissions. Regulatory
standards also contain information that
addresses emission limits on criteria
pollutants (e.g., a standard may use PM
concentration as a surrogate to measure
non-volatile metals concentration as part of
total HAP reductions).
Sections 3.9 and 3.10 of this
document discus RE and RP
adjustments. You can access
comprehensive MACT
rule-specific information
including Federal Register
publications and citations,
compliance dates, and MACT
rule contact names and phone
numbers through the UATW site
at
http://www. epa.gov/ttn/uatw/epa
rules.html
Keep in mind that nationally-derived
emission estimates or factors may not apply
to your area and may need to be adjusted
Emissions calculated using national
emission factors may vary considerably
from actual values at a specific source or
within a specific geographic area.
Know your pollutants.
For example, several VOC are considered
photochemically nonreactive by the U.S.
EPA as defined in the CAA and are not
included in VOC emissions inventories
(63 FR 17331, April 9, 1998: Part 51 "Air
Quality: Revision to Definition of VOC -
Exclusion of Methyl Acetate.")
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Table 6-1.
Issues to Consider When Estimating Criteria Pollutant Emissions From Area Sources (Continued)
For an area source inventory, you
should...
Because...
Helpful references include.
Make sure that if you survey a subset of an
area source category, you have enough
information to accurately scale the results
up to represent the entire source category.
Your estimates may accurately reflect
emissions for the subset of the category that
you survey, but will not represent emissions
for the entire category if they are scaled up
with an inappropriate adjustment factor.
oo
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An emission reporting threshold has been established to separate point from stationary area
sources and a top-down approach may be the best option available to inventory area sources
below the reporting threshold. The top-down approach is particularly useful when national or
regional estimates or emission factors are the only sources of information available on
emissions for a specific source category. These estimates may be the result of large studies
conducted by a consortium of states or by the U.S. EPA to fulfill a regulatory requirement or a
CAA mandate. The state agency may choose to use the results of such studies in a top-down
approach and allocate emissions to a smaller geographic area such as a county.
The EIIP guidance documents refer to "preferred" and "alternative" methods for each source
category. The inventory preparers, with assistance from their experienced managers, select an
emission estimation method during the planning phase of the inventory development process.
The estimation methods should be documented in the inventory preparation plan.
You can use various approaches to estimate emissions from area sources:
• Applying point source methods to area sources (a bottom-up approach);
• Conducting local activity level surveys (a bottom-up approach); and
• Applying a top-down approach.
Table 6-2 provides examples of area source categories and the associated methods used for
estimating emissions. Each method has distinct advantages and disadvantages, and you must
evaluate the merits of these methods on a source category-specific basis.
6.5.1 Applying Point Source Methods to Area Sources
There are several situations when it is appropriate to use point source methods to inventory
small sources that are included in the area source inventory:
• If there are a few area sources within the geographical area being inventoried, it
may be most practical to inventory each source individually.
• If it is very difficult to correlate available activity level data for the sources to
their emission levels: For example, some bulk gasoline storage plants are small
sources that can easily be inventoried individually. The most readily available
activity level indicator for bulk gasoline storage plants is gasoline sales in then
entire inventory area. This value cannot be directly correlated to the gasoline
throughput at individual bulk gasoline storage plants and therefore cannot be
used to calculate emissions for individual plants. Therefore, agencies should
contact the plants individually to obtain gasoline throughput data.
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Table 6-2.
Example Area Source Emission Estimation Methods
Area Source
Category
Commercial/
Consumer Solvent
Use
Architectural
Surface Coating
Gasoline
Distribution
Industrial Surface
Coating
Surface Cleaning
Operations
Dry Cleaning
Operations
Automobile
Refmishing
Graphic Arts
Facilities
Asphalt Paving
Traffic Paints
Agricultural
Pesticides
Application
Commercial
Bakeries
Structure Fires
Municipal Landfills
Residential Fuel
Combustion
Example
Estimation Method
Per capita emission
factor
Survey
Gasoline usage
Per employee
emission factor
Per employee
emission factor
Per employee
emission factor
Per capita emission
factor
Per employee
emission factor
Asphalt usage
Paint usage
Application rate,
acres treated
Per capita emission
factor
Per fire emission
factor
Landfill Gas
Emissions estimation
model
Fuel use
Activity Data
Population
Gallons of paint sold
Gallons of gasoline
sold
Employment by SIC
code
Employment by SIC
code
Employment by SIC
code
Population
Employment by SIC
code
Barrels of asphalt
applied
Gallons of paint
applied
Crop type by acre,
types of pesticides
applied
Population
Number of fires
Tons of refuse in
place, landfill age
Amount of fuel used
Source of Activity
Data
US Census data
Paint manufacturers
State DOT, State
Energy Office
State Labor
Department
State Labor
Department
State Labor
Department
US Census data
US Census data
State DOT, paving
contractors
State DOT
State Agricultural
Office, USDA
US Census data
Fire Marshall
State Solid Waste
Management Agency
Energy Information
Administration (EIA)
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Table 6-2.
Example Area Source Emission Estimation Methods (Continued)
Area Source
Category
Industrial Fuel
Combustion
Commercial/
Institutional Fuel
Petroleum Vessel
Loading/ Unloading
Aircraft Refueling
Hospital Sterilizers
Forest Fires
Breweries
Barge, Tank Car,
Railcar, Drum
Cleaning
Distilleries
Agricultural/Slash
Burning
Wineries
TSDFs (treatment,
storage, and disposal
facilities)
Superfund Sites
Open Burning of
Household Wastes
Example
Estimation Method
Fuel use
Fuel use
Petroleum products
loaded/ unloaded
Aviation fuel
consumption
Per hospital bed
emission factor
Acres burned
emission factor
State beer production
emission factor
Drum cleaning
survey
Distilled spirits
production
Acres burned
emission factor
Wine production
Survey
Survey
Survey
Activity Data
Amount of fuel used
Amount of fuel used
Gallons of fuel
transported
Gallons of fuel used
Number of hospital
beds
Acres burned
Barrels of beer
produced or sold
Number of vessels
cleaned, material
cleaned
Barrels of spirits
produced or sold
Acres burned
Barrels of wine
produced or sold
Material type,
material throughput,
treatment type
Material type,
material throughput,
treatment type
Occurrence of
burning
Source of Activity
Data
State Energy Office,
EIA
State Energy Office,
EIA
Port Authority
Waterborne
Commerce
State Energy Office,
airports
State Health
Department
State Forester
State Commerce
Office, trade groups
Trade groups, drum-
cleaning facilities
State Commerce
Office, trade groups
Extension agents,
agricultural schools
State Commerce
Office, trade groups
State Environmental
Office
State Environmental
Office
State Environmental
Office
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• If there are sufficient data to allow the agency to estimate activity levels and emissions
at the facility level: For example, records may be available from an agency showing the
location and amount of solvent handled by each dry cleaner within the inventory area.
You should decide whether an individual point source record will be coded and
maintained for each facility or whether the resulting individual activity levels and
emission estimates will be collectively handled in the area source inventory.
The various methods used to estimate emissions from point sources are described in details in
Section 5.0 of this document.
Example calculations illustrating the application of point and area estimation methods
are provided in Appendices D and E, respectively.
6.5.2 Local Activity Surveys
Surveys used for area sources will, for practical means, not achieve the same level of coverage
as those used for the larger point sources. Emissions are estimated for area sources by selecting
representative subsets of individual sources from which emission calculation parameters can be
derived and then scaling the estimates up to reflect the entire population of these sources. You
should also survey various local associations and agencies to determine what information is
maintained and can be used in the inventory area.
When planning to collect survey data for area sources it is critical that you carefully select the
subset of individual sources so that the subset is representative of the population as a whole.
For example, the emission factors presented for consumer/commercial solvent use and
architectural coatings in Volume in of the EIIP series were developed from surveys of
manufacturers. Those surveys attempted to cover as many sources as possible, and where
manufacturers could not be included, the uncovered contribution was quantified to make the
emission factors more representative of the industry as a whole.
6.5.3 Applying a Top-Down Approach
If local data are not available to develop local-level emissions, state or national data can be
apportioned to local areas using a top-down approach. There are two variations to a top-down
approach:
• Applying source test or national (or regional) derived emission factor to the
local level; or
• Allocating national (or regional) level emission estimates to the local level.
Each of these approaches is described in more detail below, and example calculations are
provided in Appendix E.
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Applying Source Test or National (or Regional) Derived Emission Factors to the Local Level
Source
Emissions from certain area source categories, especially those associated with solvent use, are
not always easily estimated by a direct measure of activity. For example, local level activity
data for the use of consumer and commercial solvent evaporation products such as waxes,
aerosol products, and window cleaners cannot be routinely determined for many local sources.
In addition, it is impractical to develop a survey that would yield such information. In such a
case, you will need to devise an emission factor that is based on a surrogate measure for
activity level, such as population. The underlying assumption behind this approach is that
emissions for some source categories can be reasonably associated with the size of the
population. The use of population as a surrogate activity level is valid for certain area source
categories such as dry cleaning, architectural surface coating, and solvent evaporation from
household products. You should not develop per capita emission factors for sources whose
emissions do not correlate well with population.
You can also use employment as a surrogate for local activity. VOC emissions-per-employee
factors are often used to estimate emissions for source categories for which an SIC code has
been assigned and for which employment data (typically by SIC code) are available at the local
level. Because many facilities within the industrial classifications of interest are point sources
of VOC emissions, you may be able to develop emissions-per-employee factors by SIC code
for area sources using data in the point source inventory. You can also use this approach where
the state/local agency surveys only a fraction of the area sources within a given category. In
this case, employment is used as an indicator to "scale up" the inventory to account collectively
for missing sources and emissions in the area source file. You can also use parameters other
than employment, such as sales data or number of facilities, to develop local emission
estimates. However, employment data are generally the most readily available parameter.
Appendix E includes example calculations illustrating the use of such emission factors for
estimating area source emissions.
To calculate emissions from area sources using an emission factor, you will need five basic
inputs to the estimation algorithm:
• Activity level or a representative surrogate;
• An emission factor (which may represent "controlled" or "uncontrolled"
emissions);
• Rule effectiveness factor;
• Rule penetration factor; and
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When applicable, information on capture and control efficiencies of any control
device when using an "uncontrolled" emission factor.
The basic emission estimation equation when using an "uncontrolled" emission factor is:
E = A x EF x (1 - CE x RE x RP)
where:
E = emission estimate for the process
A = activity level or a representative surrogate
EF = emission factor assuming no control
CE = capture efficiency x control efficiency (expressed in percent); C equals zero
if no control device is in place
RE = rule effectiveness, an adjustment to C to account for failures and
uncertainties that affect the actual performance of the control.
RP = rule penetration. Both RE and RP are applied to entire source categories
when calculating area source emission estimates
For area sources, CE can vary widely. CE values for area sources should represent the
weighted average control for the category. Area sources that are most likely to be controlled
are:
• Industrial surface coating;
• Gasoline marketing (Stage I);
• Surface cleaning; and
• Printing processes.
The basic emission estimation equation when using a "controlled" emission factor is:
E = AxEFxRExRP
where:
E = emission estimate for the process
A = activity level or a representative surrogate
EF = "controlled" emission factor
RE = rule effectiveness
RP = rule penetration
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Allocating National (or Regional) Emission Estimates to the Local Level
You can allocate national or regional level emission estimates to the local level using
representative surrogate factors.
For example, if pesticide application data are available only on a statewide basis from the
agricultural department, you could apportion these data to the area of study using the number of
acres of agricultural land. Once you have developed the local activity data, traditional emission
estimation techniques, such as nationally or locally derived emission factors are used to
estimate local-level emissions. The main disadvantage for estimating emissions using this
approach is that accuracy is lost in the allocation process.
Table 6-3 provides examples of surrogate activity indicators applicable to selected area source
categories. Appendix E includes example calculations illustrating the allocation of
national or regional level data to the local level.
6.6 Are Temporal and Spatial Allocations Necessary for Area Source Inventories?
6.6.1 Is Temporal Allocation Necessary?
Yes. You will frequently need to adjust your emissions estimates to reflect the specific time
period represented by the inventory.
6.6.2 How Do I Make Temporal Adjustments?
To calculate accurate emissions estimates for a specific inventory period, you must collect
emission rate and activity data:
• The most accurate method is to collect activity data for each specific time period
represented by the inventory. This is done by means of a survey, and is
generally not used for area source inventories, because such survey is extremely
resource intensive.
• If resources allow you to conduct a survey to collect area source information,
you should include questions to determine if seasonal emission rate variations
occur. You can collect information about production levels, working hours, fuel
consumption, or other values that could provide information pertinent to the
area source you are investigating.
• You can collect information from indirect sources such as business and labor
statistics, energy consumption data, or meteorological data. You must be
careful to use data that are both current and representative of your inventory
area, or to make the appropriate adjustments.
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Table 6-3.
Examples Of Surrogate Activity Indicators Applicable
To Selected Area Source Categories
Area Source Category
Residential fuel combustion
Commercial/institutional fuel combustion
Industrial fuel combustion
Gasoline marketing
Unpaved roads
Forest wildfires
Prescribed burning
Agricultural operations
Structure fires
Degreasing
Dry cleaning
Graphic arts/printing
Rubber and plastic manufacturing
Architectural coating
Auto body repair
Motor vehicle manufacturing
Paper coating
Fabricated metals
Machinery manufacturing
Furniture manufacturing
Flat wood products
Example Surrogate Activity Indicator(s)
Housing, population
Urban land use
Urban land use
Population, vehicle miles traveled (VMT)
County area, land use
Composite forest land
Composite forest land
Agricultural land use
Housing, population
Population, employment
Population, employment
Population, employment
Population, employment
Population, employment
Population, employment
Population, employment
Population, employment
Population, employment
Population, employment
Population, employment
Population, employment
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Table 6-3.
Examples Of Surrogate Activity Indicators Applicable
To Selected Area Source Categories (Continued)
Area Source Category
Other transportation equipment
manufacturing
Electrical equipment manufacturing
Ship building and repair
Miscellaneous industrial manufacturing
Miscellaneous solvent use
Publicly owned treatment works (POTWs)
Cutback asphalt paving
Fugitive emissions from synthetic organic
chemical manufacturing
Bulk terminal and bulk plants
Fugitive emissions from petroleum refinery
operations
Process emissions from bakeries
Crude oil and natural gas production fields
Hazardous waste treatment, storage, and
disposal facilities (TSDFs)
Example Surrogate Activity Indicator(s)
Population, employment
Population, employment
Water proximity, employment
Population, employment
Population, employment
Population
Population, VMT
Population, employment
Population, employment
Population, employment
Population, employment
Population, employment
Population, industrial land use
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If you are not able to collect data specific to the inventory period, you will need to estimate area
source emissions using an adjustment factor applied to annual activity data. Refer to
Appendix E for example calculations. Factors used to make temporal adjustments are
expressed as fractions, percentages, or ratios. Example 13 in Appendix E shows how to
estimate a temporal adjustment factor and apply it to annual activity data. Volume in of EIIP
includes adjustment factors to use as default when data specific to the inventory area is not
available.
6.6.3 What Is Spatial Allocation?
Spatial allocation is the adjustment of activity levels or emission estimates to a smaller or
larger geographic area than the area for which the activity levels or emission estimates were
prepared. Spatial allocation usually requires that you identify a surrogate indicator that can be
used for the scaling.
6.6.4 How Do I Make Spatial Adjustments ?
You can make spatial allocation adjustments based on:
• Local activity level data;
• State or national data;
• Population data; and
• Employment data.
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7.0 BIBLIOGRAPHY
EPA. 1999. 1996 National Air Quality Trends Brochure - Particulate Matter.
http://www. epa.gov/oar/aqtrnd96/brochure/pmlO.html
EPA. 1999 Information on How to Submit Air Emission Inventory Data Electronically to EPA
(Updated 7/2 7/99). http://www. epa.gov/ttn/chief/ei/eisubmit. html
EPA. April 1999a. Factor Information Retrieval (FIRE) Data System, Version 6.2. Updated
annually. U.S. Environmental Protection Agency, Office of Air Quality Planning and
Standards, Research Triangle Park, North Carolina.
EPA. April 1999b. Emissions Inventory Guidance for Implementation of Ozone and
Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze
Regulations. EPA-454/R-99-006. U.S. Environmental Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle Park, North Carolina.
EPA. May 1999. TANKS: Storage Tank Emission Estimation Software, Version 4.0. U.S.
Environmental Protection Agency, Office of Air Quality Planning and Standards, Research
Triangle Park, North Carolina.
EPA. 1998. Compilation of Air Pollutant Emission Factors, Volume I: Stationary Point and
Area Sources. Fifth Edition and Supplements, AP-42. U.S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.
EPA. May 1998. PMCalc: PMCalculator Program. U.S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.
EPA. June 1998. Landfill Gas Emissions Model, Version 2.01. U.S. Environmental
Protection Agency, Control Technology Center, Research Triangle Park, North Carolina.
EPA. December 1998. National Air Pollutant Emission Trends Update: 1990-1997.
EPA-454/E-98-007. U.S. Environmental Protection Agency, Office of Air Quality Planning
and Standards, Research Triangle Park, North Carolina.
EPA, Region 5 - Air and Radiation. 1997. Criteria Pollutants.
http://www. epa.gov/reg5oair/emission/critpllt. htm#3
EPA. 1997. EPA 's Updated Clean Air Standards: A Common Sense Primer.
September 1997. http://www.epa.gov/oar/primer/
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EPA. November 1995a. Protocol for Equipment Leak Emission Estimates.
EPA-453/R-95-017. U.S. Environmental Protection Agency, Office of Air Quality Planning
and Standards, Research Triangle Park, North Carolina.
EPA. November 1995b. WATERS Modeling Program, Version 4.0. U.S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park,
North Carolina.
EPA. January 1994. Rule Effectiveness Guidance: Integration of Inventory, Compliance, and
Assessment Applications. EPA-452/R-94-001. U.S. Environmental Protection Agency, Office
of Air Quality Planning and Standards, Research Triangle Park, North Carolina.
EPA. November 1994. CHEMDAT8 Modeling Program. U.S. Environmental Protection
Agency, Office of Air Quality Planning and Standards, Research Triangle Park, North
Carolina.
EPA. August 1992b. MECH: Fugitive Dust Program for Unpaved Roads. U.S.
Environmental Protection Agency, Office of Air Quality Planning and Standards, Research
Triangle Park, North Carolina.
EPA. November 1992. Guidelines for Estimating and Applying Rule Effectiveness for
Ozone/CO State Implementation Plan Base Year Inventories. EPA-452/R-92-010. U.S.
Environmental Protection Agency, Office of Air Quality Planning and Standards, Research
Triangle Park, North Carolina.
EPA. May 1991. Procedures for the Preparation of Emission Inventories for Carbon
Monoxide and Precursors of Ozone, Volume I: General Guidance for Stationary Sources.
EPA-450/4-91-016. U.S. Environmental Protection Agency, Office of Air Quality Planning
and Standards, Research Triangle Park, North Carolina.
EPA. July 1991. Procedures for Preparing Emissions Projections. EPA-450/4-91-019. U.S.
Environmental Protection Agency, Office of Air Quality Planning and Standards, Research
Triangle Park, North Carolina.
EPA. 1988. Control of Open Fugitive Dust Sources. U.S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.
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8.0 DEFINITIONS OF COMMONLY USED TERMS
Activity Level/Factor is a measurable factor that is directly or indirectly related to the
emissions of a process. An emission estimate is calculated by multiplying an activity level by
an emission factor. The activity level is either directly related to the amount of emissions (as in
the case of the amount of fuel used in a combustion process), or is a more easily measured
surrogate, such as population for consumer product usage.
Actual Emissions are the actual rate of emissions of a pollutant from an emissions unit
calculated using the unit's actual operating hours, production rates, and types of materials
processed, stored, or combusted during the selected time period.
Allowable Emissions are the emissions rate that represents a limit on the emissions that can
occur from an emissions unit. This limit may be based on a federal, state, or local regulatory
emission limit determined from state or local regulations and/or 40 Code of Federal
Regulations (CFR) Parts 60, 61, and 63.
Ambient Standards Specify the target threshold concentrations and exposure durations of
pollutants based on criteria gauged to protect human health and the welfare of the environment.
Ambient standards are not emissions limitations on sources, but usually result in such limits
being placed on source operation as part of a control strategy to achieve or maintain an ambient
standard.
Annual Emissions are actual emissions for a plant, point, or process, either measured or
calculated.
Area Sources are smaller sources that do not qualify as point sources under the relevant
emissions cutoffs. Area sources encompass more widespread sources that may be abundant,
but that, individually, release small amounts of a given pollutant. These are sources for which
emissions are estimated as a group rather than individually. Examples typically include dry
cleaners, residential wood heating, auto body painting, and consumer solvent use. Area sources
generally are not required to submit individual emissions estimates.
Attainment Area is an area considered to have air quality as good as or better than the National
Ambient Air Quality Standards (NAAQS) as defined in the CAA. Note that an area may be in
attainment for one or more pollutants but be a nonattainment area for one or more other
pollutants.
Biogenic Emissions are defined as all pollutants emitted from non-anthropogenic sources.
Example sources include trees and vegetation, and microbial activity.
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Bottom-Up Approach means emission estimates are developed specifically for individual
sources and summed to obtain state- or county-level emission estimates.
Carbon Monoxide (CO) is a colorless, odorless gas that depletes the oxygen-carrying capacity
of blood. Major sources of CO emissions include industrial boilers, incinerators, and motor
vehicles.
Continuous Emissions Monitor (CEM) is any monitor that "continuously" measures
(i.e., measures with very short averaging times) and records emissions. In addition to
measuring and recording actual emissions during the time of monitor operation, CEM data can
be used to estimate emissions for different operating periods and longer averaging times.
Control Efficiency is the emission reduction efficiency of a primary control device, which
shows the amount of reduction of a particular pollutant for a process' emissions due to controls
or material change. Control efficiency is usually expressed as a percentage of in tenths.
Criteria Pollutants are carbon monoxide (CO), lead (Pb), nitrogen oxides (NOX), sulfur
dioxide (SO2), Ozone (O3), particulate matter of aerodynamic diameter less than or equal to
10 micrometers (PM10) and parti culate matter of aerodynamic diameter less than or equal to
2.5 micrometers (PM2 5).
Data Quality Indicators are qualitative and quantitative descriptors used to interpret the degree
of acceptability or utility of data to the user. The principal data quality indicators are accuracy,
comparability, completeness, and representativeness.
Data Quality Objectives (DQOs) are qualitative and quantitative statements developed to
ensure that data of known and appropriate quality are obtained to support decisions or actions.
DQOs encompass all aspects of data collection, analysis, validation, and evaluation.
Double Counting means estimation and counting of estimated emissions twice in an inventory
for the same source category. Area source inventories are at risk of double counting emissions
from two sources because of point and area source overlap and overlap between two area
sources.
Emission means pollution discharged into the atmosphere from smokestacks, other vents, and
surface areas of commercial or industrial facilities; from residential chimneys; and from motor
vehicle, locomotive, aircraft, or other nonroad engines.
Emission Factors are ratios that relate emissions of a pollutant to an activity level at a plant
that can be easily measured, such as an amount of material processed, or an amount of fuel
used. Given an emission factor and a known activity level, a simple multiplication yields an
estimate of the emissions. Emission factors are developed from separate facilities within an
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industry category, so they represent typical values for an industry, but do not necessarily
represent a specific source. Published emission factors are available in numerous sources.
Emission Inventory is a listing, by source, of the amount of air pollutants discharged into the
atmosphere of a community.
Emission Standards are a general type of standard that limit the mass of a pollutant
that may be emitted by a source. The most straightforward emissions standard is a simple
limitation on mass of pollutant per unit time (e.g., pounds of pollutant per hour).
Engineering Judgment is made when the specific emission estimation techniques such as
stack testing, material balance, or emission factor are not possible. This estimation is usually
made by an engineer familiar with the specific process, and is based on whatever knowledge
may be available.
Fuel Analysis is a method for estimating emissions based on the application of conservation
laws. The presence of certain elements in fuels may be used to predict their presence in
emission streams. For example, SO2 emissions from oil combustion can be calculated based
on the concentration of sulfur in the oil. This approach assumes complete conversion of sulfur
to SO2. Therefore, for every round of sulfur (molecular weight = 32g) burned, two pounds of
SO2 (molecular weight = 64g) are emitted.
Fugitive Emissions are emissions from sources that are technically infeasible to collect and
control (e.g., storage piles, wastewater retention ponds).
Geogenic Emissions are defined as emissions from natural occurrences, primarily the result of
gas seep and soil wind erosion.
Growth Factors are surrogate indicators based on economic or demographic parameters that
predict the proportional change in the activity level or emissions for a particular emissions
source.
Hazardous Air Pollutants (HAPs) are listed in Section 112(b) of the 1990 Clean Air Act
Amendments (CAAA). The CAAA specifies a list of 189 HAPs to be subject to regulation.
The list of HAPs includes relatively common pollutants such as formaldehyde, chlorine,
methanol, and asbestos, as well as numerous less common substances. Pollutants may, under
certain circumstances, be added to or deleted from the list. To date, one pollutant has been
deleted from the list, resulting in 188 HAPs.
Inventory Area is generally defined by political boundaries such as county or state boundaries,
where the jurisdictions that are included in an inventory area make up an air basin or
experience common air problems. The pollutant or the type of air pollution inventory will
determine the exact geographic area that will be covered.
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Inventory Preparation Plan is a document that discusses staff assignments and
responsibilities, establishes a commitment to the inventory development and QA/QC processes,
and establishes a commitment to personnel training and project documentation requirements. It
may either be integrated with the quality assurance plan or a separate document.
Lead (Pb) is an element that causes several types of developmental effects in children
including anemia, neurobehavioral alterations, and metabolic alterations. Lead is emitted from
industries such as battery manufacturing, lead smelters, and incineration. Although regulated
in highway fuels, lead may also be emitted from unregulated off-highway mobile sources.
Material Balance is a method for estimating emissions that attempts to account for all the
inputs and outputs of a given pollutant. If inputs of a material to a given process are known
and all outputs except for air emissions can be reasonably well quantified, then the remainder
can be assumed to be an estimate of the amount lost to the atmosphere for the process.
Mathematical Emission Model is an emission estimation technique that uses a mathematical
model to estimate emissions. A very simple mathematical model multiplies an emission factor
and an activity level to produce an emission estimate. A more complex model may involve
multiple parameters and iterations in the calculation process. A mathematical model may be
used by inventory preparers as an equation or as a computer program.
Maximum Achievable Control Technology (MACT) Standards are emissions limitations
developed under Section 112(d) of the CAAA National Emissions Standards for Hazardous Air
Pollutants (NESHAP). The limitations are based on the best demonstrated control technology
or practices in similar sources to be applied to point sources emitting one or more of the listed
HAPs.
Mobile Sources include all nonstationary sources, such as automobiles, trucks, aircraft, trains,
construction and farm equipment, and others. Mobile sources are a subcategory of area
sources, and are generally not required to submit individual emissions estimates.
National Ambient Air Quality Standards (NAAQS) are the main ambient standards for the
following criteria pollutants: carbon monoxide, lead, nitrogen oxides, sulfur oxides, ozone,
particulate matter of aerodynamic diameter less than or equal to 10 micrometers and particulate
matter of aerodynamic diameter less than or equal to 2.5 micrometers.
National Emissions Standards for Hazardous Air Pollutants (NESHAP) are a class of
standards emitting emissions of HAPs. The NESHAPs are published in
40 CFR Parts 61 and 63.
New Source Performance Standards (NSPS) are promulgated for criteria, hazardous, and
other pollutant emissions from new, modified, or reconstructed sources that the
U.S. Environmental Protection Agency (EPA) determines contribute significantly to air
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pollution. These are typically emission standards, but may be expressed in other forms such as
concentration and opacity. The NSPS are published in 40 Code of Federal Regulations (CFR)
Part 60.
Nitrogen Oxides (NOX) are a class of compounds that are respiratory irritants and that react
with volatile organic compounds (VOCs) to form ozone (O3). The primary combustion
product of nitrogen is nitrogen dioxide (NO2). However, several other nitrogen compounds are
usually emitted at the same time (nitric oxide [NO], nitrous oxide [N2O], etc.), and these may
or may not be distinguishable in available test data. They are usually in a rapid state of flux,
with NO2 being, in the short term, the ultimate product emitted or formed shortly downstream
of the stack. The convention followed in emission factor documents is to report the
distinctions wherever possible, but to report total NOX on the basis of the molecular weight of
NO2. NOX compounds are also precursors to acid rain. Motor vehicles, power plants, and
other stationary combustion facilities emit large quantities of NOX.
Ozone (O3) is a colorless gas that damages lungs and can damage materials and vegetation. It
is the primary constituent of smog, and is formed primarily when nitrogen oxides (NOX) and
volatile organic compounds (VOCs) react in the presence of sunlight. It is also emitted in
insignificant quantities from motor vehicles, industrial boilers, and other minor sources.
Particulate Matter of aerodynamic diameter less than or equal to 10 micrometers (PM10) is
a measure of small solid matter suspended in the atmosphere. Small particles can penetrate
deeply into the lung where they can cause respiratory problems. Emissions of PM10 are
significant from fugitive dust, power plants, commercial boilers, metallurgical industries,
mineral industries, forest and residential fires, and motor vehicles.
Particulate Matter of aerodynamic diameter less than or equal to 2.5 micrometers (PM2 $) is
a measure of fine particles of particulate matter that come from fuel combustion, agricultural
burning, woodstoves, etc. On November 27, 1996, the U.S. Environmental Protection Agency
proposed to revise the current primary (health-based) PM standards by adding a new annual
PM2 5 standard.
Plant-level Emissions are consolidated for an entire plant or facility. A plant may contain one
or many pollutant-emitting sources.
Plant-level Reporting is generally required if total emissions from a plant (which may be
composed of numerous individual emission points) meet the point source cutoff. These data
can be used by a state to conduct a detailed estimate of emissions from that plant. The plant-
level reporting used by most air pollution control agencies generally requires that the facility
provide data that apply to the facility as a whole. Such data include the number of employees
and the Standard Industrial Classification (SIC) code designation for the plant. A plant usually
has only one SIC code denoting the principal economic activity of the facility. For the purpose
of clearly identifying and tracking emissions data, each plant is generally assigned a plant
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(alternatively, "facility") name and number. The plant is also identified by geographic or
jurisdictional descriptors such as air quality control region, county, address, and Universal
Transverse Mercator (UTM) grid coordinates (or latitude/longitude) that identify a coterminous
location. An owner or operator engaged in one or more related activities is also identified. In
some cases, plantwide emissions may be reported at the plant level.
Point-level Emissions typically represent single stacks or vents individually large enough to be
considered point sources.
Point-level Reporting includes specific data for individual emission points (typically stacks).
These data are more detailed than that submitted in plant-level reporting and may include
emission-related and modeling information such as stack height of the release point, diameter
of the stack, emission rate, method of determination, fugitive emissions, gas exit velocity from
a stack, gas temperature, and operating schedule. Source identification information, as
described under plant-level reporting, is usually also required at the point level to ensure that
emission data for a single plant remain clearly identified. Regulatory agencies generally
maintain individual emission-related records at the point level.
Point Sources are large, stationary, identifiable sources of emissions that release pollutants into
the atmosphere. Sources are often defined by state or local air regulatory agencies as point
sources when they annually emit more than a specified amount of a given pollutant, and how
state and local agencies define point sources can vary. Point sources are typically large
manufacturing or production plants. They typically include both confined "stack" emission
points as well as individual unconfmed "fugitive" emission sources.
Within a given point source, there may be several emission points that make up the point
source. Emissions point refers to a specific stack, vent, or other discrete point of pollution
release. This term should not be confused with point source, which is a regulatory distinction
from area and mobile sources. The characterization of point sources into multiple emissions
points is useful for allowing more detailed reporting of emissions information.
Potential Emissions are the potential rate of emissions of a pollutant from an emissions unit
calculated using the unit's maximum design capacity. Potential emissions are a function of the
unit's physical size and operational capabilities.
Process Emissions are emissions from sources where an enclosure, collection system, ducting
system, and/or stack (with or without an emission control device) is in place for a process.
Process emissions represent emissions from process equipment (other than leaks) where the
emissions can be captured and directed through a controlled or uncontrolled stack for release
into the atmosphere.
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Quality Assurance (QA) is a planned system of activities designed to provide assurance that
the quality control program is actually effective. QA is a process that involves both the
inventory team and external reviewers to insure the overall quality of the inventory.
Quality Control (QC) comprises the activities undertaken by all members of the inventory
team during the inventory preparation that will result in the correction of specific problems
such as mistaken assumptions, lost or uncollected data, and calculation and data entry errors.
Reported Emissions are those emission estimates that are submitted to a regulatory agency.
Emissions inventories can be used for a variety of purposes such as State Implementation Plan
(SIP) base year inventories, environmental compliance audits, air quality rule applicability, and
reporting information in an air quality permit application. Emissions can be reported on an
actual, potential, or maximum basis. Many state and local air pollution control agencies have
rules and regulations that define an allowable emission value for a particular piece of
equipment. Because of this, a facility should first define the purpose of the inventory and then
choose the appropriate means of reporting emissions to the regulatory agency. For example,
SIP base year inventories for point sources would contain actual emissions. However,
regulatory applicability and air quality permit applications can require that actual, allowable,
and potential emissions be reported.
Rule Effectiveness is the measure of a regulatory program to achieve all of the emission
reductions possible, which reflects the assumption that controls are typically not 100 percent
effective, because of equipment downtime, upsets, decreases in control efficiencies, and other
deficiencies in emission estimates. RE is used to adjust the control efficiency.
Rule Penetration is the percentage of an area source category that is covered by an applicable
regulation.
SCC is a source classification code. It is a process-level code that describes the equipment or
operation emitting pollutants.
SIC is a standard industrial classification code. It is the U.S. Department of Commerce's
categorization of businesses by their products or services.
Source Tests are short-term tests used to collect emissions data that can then be extrapolated to
estimate long-term emissions from the same or similar sources. Uncertainties arise when
source test results are used to estimate emissions under process conditions that differ from
those under which the test was performed.
Spatial Allocation entails assignment of activity levels or emission estimates to a smaller or
larger geographic area than the area for which the activity level or emission estimate was
prepared. Allocation usually requires the identification of a surrogate indicator that can be used
for scaling.
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Stack Diameter is a stack physical diameter.
Stack Height is a stack physical height above the surrounding terrain.
State Implementation Plan (SIP) is a state plan approved by EPA for the establishment,
regulation, and enforcement of air pollution standards.
Sulfur Oxides (SOX) are a class of colorless, pungent gases that are respiratory irritants and
precursors to acid rain. Sulfur oxides are emitted from various combustion or incineration
sources, particularly from coal combustion.
Surveys are a method to collect inventory data using telephone or written questionnaires that
are answered by manufacturers or suppliers of products, or by representatives at the facilities or
sites where the emitting processes take place. An area source survey may also include review
and data collection from existing air pollution permits within an agency. Surveys for area
source inventories usually survey a subset of the population of sources.
Top-Down Approach means emission estimates are developed from emission factors that were
developed from test data or on the national- or regional-level. Estimates are scaled to the
inventory area using some measure of activity data thought to be directly or indirectly related to
the emissions, and some measure of emissions that can be applied to these data.
Volatile Organic Compounds (VOC) as cited in 63 FR 17331, April 19, 1998, means any
compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic
carbides or carbonates, and ammonium carbonate that participates in atmospheric
photochemical reactions. This includes any such organic compound other than the following,
which have been determined to have negligible photochemical reactivity:
• methane
• ethane
• methylene chloride (dichloromethane)
• 1,1,1 -tri chl oroethane (methyl chl oroform)
1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113)
• trichlorofluoromethane (CFC-11)
• dichlorodifluoromethane (CFC-12)
• chlorodifluoromethane (HCFC-22)
trifluoromethane (HFC-23)
l,2-dichloro-l,l,2,2-tetrafluoroethane (CFC-114)
• chloropentafluoroethane (CFC-115)
l,l,l-trifluoro-2,2-dichloroethane (HCFC-123)
1,1,1,2-tetrafluoroethane (HFC-134a)
1,1-dichloro-l-fluoroethane (HCFC-141b)
l-chloro-l,l-difluoroethane (HCFC-142b)
-------
2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124)
pentafluoroethane (HFC-125)
1,1,2,2-tetrafluoroethane (HFC-134)
1,1,1 -trifluoroethane (HFC-143a)
1,1-difluoroethane (HFC-152a)
parachlorobenzotrifluoride (PCBTF)
cyclic, branched, or linear completely methylated siloxanes
acetone
perchloroethylene (tetrachloroethylene)
3,3-dichloro-1,1,1,2,2-pentafluoropropane (HCFC-225ca)
1,3-dichloro-1,1,2,2,3-pentafluoropropane (HCFC-225cb)
1,1,1,2,3,4,4,5,5,5-decafluoropentane (HFC 43-10mee)
difluoromethane (HFC-32)
ethylfluoride (HFC-161)
l,l,l,3,3,3-hexafluoropropane(HFC-236fa)
1,1,2,2,3-pentafluoropropane (HFC-245ca)
1,1,2,3,3-pentafluoropropane (HFC-245ea)
1,1,1,2,3-pentafluoropropane (HFC-245eb)
l,l,l,3,3-pentafluoropropane(HFC-245fa)
1,1,1,2,3,3-hexafluoropropane (HFC-236ea)
1,1,1,3,3-pentafluorobutane (HFC-365mfc)
chlorofluoromethane (HCF-31)
1 -chloro-1 -fluoroethane (HCFC-151 a)
1,2-dichloro-1,1,2-trifluoroethane (HCFC-123a)
1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane(C4F9OCH3)
2-(difluoromethoxymethyl)-l,l,l,2,3,3,3-heptafluoropropane((CF3)2CFCF2OCH3)
1-ethoxy-l, 1,2,2,3,3,4,4, 4-nonafluorobutane (C4F9OC2H5)
2-(ethoxydifluoromethyl)-l,l,l,2,3,3,3-heptafluoropropane((CF3)2CFCF2OC2H5)
methyl acetate and perfluorocarbon compounds which fall into these classes:
(i) cylic, branched, or linear, completely fluorinated alkanes
(ii) cylic, branched, or linear, completely fluorinated ethers with no unsaturations
(iii) cylic, branched, or linear, completely fluorinated tertiary amines with no
unsaturations and
(iv) sulfur containing perfluorocarbons with no unsaturations and with sulfur
bonds only to carbon and fluorine.
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8-10
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APPENDICES
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Contents
A List of EIIP Documents
B Clearing Up the Rule Effectiveness Confusion
C List of EIIP Preferred and Alternative Methods By Source Category
D Point Sources Example Calculations
E Area Sources Example Calculations
F Overview of Reference Materials
G List of Emission Estimation Models and Emission Factor Resources
H List of L&E Documents
I Options for Data Reporting
J 1997 Criteria Pollutants Emissions By Source Category
K List of Potential Point Source Categories By Pollutant
L List of Potential Area Source Categories By Pollutant
M Guidance On How To Conduct Screening Studies
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APPENDIX A
LIST OF AVAILABLE EIIP DOCUMENTS
http://www.epa.gov/ttn/chief/eiip/
(Current as of August 1999)
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Contents
Section Page
Volume I: Introduction to the EIIP A-l
Volume II: Point Sources A-l
Volume HI: Area Sources A-2
Volume IV: Mobile Sources A-3
Volume V: Biogenic Sources A-3
Volume VI: Quality Assurance Procedures A-3
Volume VII: Data Management Procedures A-4
Volume VIE: Estimating Greenhouse Gas Emissions A-4
A-ii
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A-iii
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List of Available EIIP Documents
Volume I: Introduction to the EIIP
Introduction and Use of EIIP Guidance for Emissions Inventory Development
Volume II: Point Sources
Chapter 1: Introduction to Stationary Point Source Emission Inventory Development
Chapter 2: Preferred and Alternative Methods for Estimating Air Emissions from
Boilers
Chapter 3: Preferred and Alternative Methods for Estimating Air Emissions from
Hot-Mix Asphalt Plants
Chapter 4: Preferred and Alternative Methods for Estimating Air Emissions from
Equipment Leaks
Chapter 5: Preferred and Alternative Methods for Estimating Air Emissions from
Wastewater Collection and Treatment Facilities
Chapter 6: Preferred and Alternative Methods for Estimating Air Emissions from
Semiconductor Manufacturing
Chapter 7: Preferred and Alternative Methods for Estimating Air Emissions from
Surface Coating Operations
Chapter 8: Preferred and Alternative Methods for Estimating Air Emissions from Paint
and Ink Manufacturing
Chapter 9: Preferred and Alternative Methods for Estimating Air Emissions from
Secondary Metal Processing
Chapter 10: Preferred and Alternative Methods for Estimating Air Emissions from Oil
and Gas Field Production and Processing Operations
Chapter 11: Preferred and Alternative Methods for Estimating Air Emissions from
Plastic Products Manufacturing
Chapter 12: How to Incorporate the Effect of Air Pollution Control Device Efficiencies
and Malfunctions into Emission Inventory Estimates (draft)
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Chapter 13: Technical Assessment Paper: Available Information for Estimating Air
Emissions from Stone Mining and Quarrying Operations
Volume III: Area Sources
Chapter 1: Introduction to Area Source Emission Inventory Development
Chapter 2: Residential Wood Combustion
ChapterS: Architectural Surface Coating
Chapter 4: Dry Cleaning
Chapter 5: Consumer and Commercial Solvent
Chapter 6: Solvent Cleaning
Chapter 7: Graphic Arts
Chapter 8: Industrial Surface Coating
Chapter 9: Pesticides - Agricultural and Nonagricultural
Chapter 10: Agricultural Operations
Chapter 11: Gasoline Marketing
Chapter 12: Marine Vessel Loading, Ballasting and Transit
Chapter 13: Autobody Refmishing
Chapter 14: Traffic Paints
Chapter 15: Municipal Landfills
Chapter 17: Asphalt Paving
Chapter 18: Structure Fires
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Volume IV: Mobile Sources
Chapter 1: Preferred and Alternative Methods for Gathering and Locating Specific
Emission Inventory Data
Chapter 2: Use of Locality-Specific Transportation Data for the Development of Mobile
Source Emission Inventories
Chapter 3: Guidance for Estimating Lawn and Garden Equipment Activity Levels
Volume V: Biogenic Sources
Biogenic Sources Preferred Methods
Volume VI: Quality Assurance Procedures
Chapter 1: Introduction: The Value of QA/QC
Chapter 2: Planning and Documentation
Chapter 3: General QA/QC Methods
Chapter 4: Evaluating the Uncertainty of Emission Estimates
Chapter 5: Model QA Plan
Appendix A: Example Audit Report
Appendix B: Technical Systems Audit Checklist Example
Appendix C: Example 1 of Data Quality Audit Checklist
Appendix D: Example 2 of Data Quality Audit Checklist
Appendix E: Performance Evaluation Checklist Example
Appendix F: EIIP Recommended Approach to Using the Data Attribute System
(DARS)
DARS User Manual, Beta Version 1.1
DARS Software Beta Version 1.1
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Volume VII: Data Management Procedures
EIIP Phase I Data Model
EIIP EDI Implementation Guideline (for air emission modeling)
Volume VIII: Estimating Greenhouse Gas Emissions
Introduction to Estimating Greenhouse Gas Emissions (Draft)
Chapter 1: Methods for Estimating Greenhouse Gas Emissions from Combustion of
Fossil Fuels (Draft)
Chapter 2: Methods for Estimating Greenhouse Gas Emissions from Industrial Processes
(Draft)
Chapter 3: Methods for Estimating Methane Emissions from Natural Gas and Oil
Systems (Draft)
Chapter 4: Methods for Estimating Methane Emissions from Coal Mining (Draft)
Chapter 5: Methods for Estimating Greenhouse Gas Emissions from Municipal Waste
Disposal (Draft)
Chapter 6: Methods for Estimating Methane Emissions from Domesticated Animals
(Draft)
Chapter 7: Methods for Estimating Greenhouse Gas Emissions from Manure
Management (Draft)
Chapter 8: Methods for Estimating Methane Emissions from Flooded Rice Fields (Draft)
Chapter 9: Methods for Estimating Greenhouse Gas Emissions from Agricultural Soils
(Draft)
Chapter 10: Methods for Estimating Carbon Dioxide and Sinks from Emissions from
Forest Management (Draft)
Chapter 11: Methods for Estimating Greenhouse Gas Emissions from Burning of
Agricultural Crop Wastes (Draft)
Chapter 12: Methods for Estimating Greenhouse Gas Emissions from Municipal Waste
Water (Draft)
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Chapter 13: Methods for Estimating Methane and Nitrous Oxide Emissions from Mobile
Combustion (Draft)
Chapter 14: Methods for Estimating Methane and Nitrous Oxide Emissions from
Stationary Combustion (Draft)
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APPENDIX B
CLEARING UP THE RULE EFFECTIVENESS CONFUSION
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Clearing Up the Rule Effectiveness Confusion
Introduction
Since its formation, EPA has been implementing rules and regulations that require states to
reduce the amount of pollution being emitted into the atmosphere. Achieving the air quality
anticipated by implementing a particular rule has not always been successful despite imposition
of numerous emission controls. In 1987 EPA acknowledged that existing air quality regulations
were not resulting in sufficient emission reductions to reach acceptable levels of air quality. The
November 24, 1987 Federal Register said "The EPA believes that one reason ozone levels have
not declined as much as expected is that reductions from national and local control measures
have not been as high as expected."1 This Federal Register further stated that "the effectiveness
(i.e., the ratio of actual reductions to expected reductions expressed as a percentage) of some
rules is much lower than 100 percent." To correct or compensate for the lower than anticipated
amount of reductions, the Federal Register notice stated that "for both new and existing rules,
EPA proposes to allow States to assume not more than 80 percent of full effectiveness unless
adequate higher levels are adequately demonstrated." Said another way, "we don't believe your
rule will get as much reduction as you think it will." This under-performance can result from:
• Some sources not implementing (or not implementing all the time) controls
required by the rule;
• Some sources not installing sufficient control equipment to achieve required
emission rate;
• Some sources operating installed control equipment at less than rated control
efficiency;
• New source being introduced into the local area covered by the rule.
Any of these situations could result in attainment year emissions being higher than anticipated.
Even though an individual source's emission rate is reduced to that specified in a state rule, the
overall reduction within the state may not be as great because of the above considerations.
The 1987 Federal Register defines "effectiveness" as:
T,™ .. Actual Reductions
Effectiveness = (1)
Expected Reductions
For complete compliance to occur, effectiveness must equal 100 percent. This Federal Register
recognizes however, that effectiveness is usually not 100 percent. To adjust for non-compliance,
the Federal Register limits the amount of reduction that a state can anticipate. This forces policy
B-l
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planners to account for less than complete compliance. For example, if an agency implemented a
rule to reduce emissions by 100 tpy (expected reduction), the Federal Register suggests that the
actual reduction will not be as great as the expected reduction (Equation 1). For the 100 tpy goal
to be met (i.e., "effectiveness" to be 100 percent), the actual reduction in Equation 1 must be
modified as follows:
„ — .. Reduction Target x (Empirical Factor)
Effectiveness = — (2)
Expected Reduction
Where:
Expected Reduction = Emission reduction required as estimated by modeling to meet air
quality standard
In this example, Equation 2 becomes:
inn0/ - Reduction Target x 0.8
100
Solving for Reduction target: Reduction target =125 tpy
Policy makers then develop control strategies based on this Reduction target value. If an agency
implements a rule to reduce emissions by 100 tpy, the policy makers must target a 125 tpy
reduction to be able to achieve the needed 100 tpy. Note that the results of equation 2 do not
reflect the accuracy of the emission estimates, but only adjust for the past history of complying
with a new rule.
r\
The 1992 Federal Register1 defines rule effectiveness as:
„ , „ — .• m-r-\ Actual Reduction
Rule Effectiveness (RE) = (3)
Expected Reduction
Where:
Actual reduction = (base year emissions) - (current year emission estimates)
In Equation 3, the new term "RE" is an indicator that compares the amount of actual emission
reduction to the expected reduction. This metric is useful to decision makers as they evaluate
how well their policies are achieving the intended goals or how effective the rule is in achieving
expected reductions. For example, assume an agency modeling exercise indicated that 100 tpy
B-2
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reduction is needed in 10 years to be able to reach attainment status. Also assume the base year
inventory is 200 tpy. If a 50 tpy reduction is achieved 5 years into the implementation period,
then the RE = (200 - 150)7100 = 50 percent. At the end of 10 years, if the entire 100 tpy has been
removed, then the RE = (200 - 100)7100 = 100 percent.
Introducing the factors contained in these equations acknowledges the reality that, in an
imperfect world, a rule intended to reduce emissions and improve air quality does not always
work as planned. Equation 2 offers, for planning purposes, an empirical solution to this problem
while Equation 3 measures the effectiveness of the solution after controls are implemented. The
empirical approach assumes that only 80 percent (or higher if an agency can substantiate) of the
required control will be achieved. To offset this shortfall, additional controls are needed. This
concept was further supported in the April 16, 1992 Federal Register. Under HI(A)(2)(a)(2) it is
stated that "one hundred percent rule effectiveness is the ability of a regulatory program to
achieve all the emission reductions at all sources at all times." The "extra" controls in
Equation 2 compensate for parts of the air quality strategy that are not completely implemented
"at all of the sources all of the time".
As the air quality control community became more sophisticated, it realized that other causes
could be contributing to the inability to reach acceptable air quality levels. Two areas of concern
are the accuracy of air quality model predictions (air quality modeling issues will not be
addressed in this discussion) and the accuracy of the emission inventory accounting process
(quantity of emissions represented in the inventory). Policy makers use emission estimates to
help develop new rules that will cause the removal of a specified quantity of pollutant. They
assume that removing this amount of pollutant will lead to acceptable air quality. The amount to
be removed is usually selected as a result of various air quality modeling exercises. If the initial
quantity of emissions used in the model calculations is incorrect, then the amount of pollutant to
be reduced, as calculated by the model, may also be incorrect.
To offset an assumed underestimate of emissions, states are required to apply a compensation
factor to facility control device efficiency values. This action has the effect of reducing the
assumed efficiency of the control device (a reasonable assumption since control equipment may
fail, be offline due to equipment maintenance, and process upsets occur) and increasing
individual source emission estimates. This factor, also called Rule Effectiveness, has a default
value of 80 percent.
Very few sources measure their emissions directly using continuous emission monitors (CEM).
Uncontrolled emissions at sources not monitored by CEMs are estimated using the following
equation:
Emissions = Emission Factor x Activity Data (4)
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If RE is used, the equation to calculate emissions from a facility containing a control device
becomes:
Emissions = Emission Factor x Activity Data x (1 -CE x RE) (5)
Where:
CE = manufacturer stated control efficiency
The definition of RE in Equations 3 and in Equation 5 are very different. Equation 3 provides
policy makers with a method to measure the amount of reduction at a point in time and judge the
success of a particular rule. Equation 5 adjusts individual facility estimates to compensate for
assessment techniques that do not account for all emissions. Even though the philosophy behind
the emission adjustments is different in each case, the same term - RE, is used for both situations.
Why Confusion Exists
In 1992, EPA issued "Guidelines for Estimating and Applying Rule Effectiveness for Ozone/CO
State Implementation Plan Base Year Inventories." Under section 1.2 the document states "The
appropriate method for determining and using RE depends upon the purpose for the
determination: compliance program or inventory. RE discussed outside the particular purpose
may be generically referred to as control effectiveness. The following three common uses for a
control effectiveness estimate have historically been called rule effectiveness:
• Identifying and addressing weakness in control strategies and regulations related
to compliance and enforcement activities (more accurately call Compliance
Effectiveness};
• Defining or redefining the control strategy necessary to achieve the required
emissions reductions designated in the CAAA (more accurately called Program or
SIP Design Effectiveness); and
• Improving the accuracy or representativeness of emission estimates across a
nonattainment area (hereafter called Rule Effectiveness)" (3)
"The inventory RE is an adjustment to estimated emissions data to account for the emissions
underestimates due to compliance failures and the inability of most inventory techniques to
include these failures in an emission estimate. The RE adjustment accounts for known
underestimates due to noncompliance with existing rules, control equipment downtime or
operating problems and process upsets. The result is a better estimate of expected emission
reductions and control measure effectiveness in future years".3
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Previous paragraphs provide definitions of Compliance effectiveness and Rule effectiveness and
try to make a distinction between the two. Despite these distinctions, the second sentence of the
preceding paragraph inadvisely combines concepts of both rule noncompliance and the problem
of overestimating collection efficiency of control equipment. Even though there is a recognition
that the two situations are different, the RE term is used interchangeably in each of these
examples.
Rule Effectiveness Guidance: Integration of Inventory, Compliance, and Assessment
Applications was issued in January 1994. In the Introduction, the document states that "Rule
Effectiveness (RE) is a generic term for identifying and estimating the uncertainty in emission
estimates caused by failures and uncertainties in emission control programs. It is a measure of
the extent to which a rule actually achieves its desired emission reductions." Implying a second
definition, the Introduction further states that "rule effectiveness accounts for identifiable
emission underestimates due to factors including noncompliance with existing rules, control
equipment downtime, operating and maintenance problems, and upsets." As was previously
noted, the RE term is again used in different contexts within the same section of the same
document.
This Guidance document contributes further to the confusion by using apparently different
definitions of rule effectiveness. The Glossary defines Rule Effectiveness as "a generic term for
identifying and estimating the uncertainties in emission estimates caused by failures and
uncertainties in emission control programs. Literally, it is the extent to which a rule achieves the
desired emission reductions."
Based on past history it is understandable that, over time, the inventory community has used RE
to describe different situations and often interchanging the definitions during the same
discussion. The RE definition has evolved, taking on slightly different meanings, depending on
the group using the term and the program to which it is being applied. Confusion results because
the inventory community often uses the term RE without indicating the context in which it is
being applied. Mangat, in a paper presented at an emission inventory conference in 1992 and in
a subsequent EIJP paper, recognized that dissimilar definitions were being used and tried to
explain the differences.
Solutions to the Confusion
RE is currently being used to describe and solve unrelated problems. In one case it is being used
to address the failure of control equipment to operate at its stated efficiency for 100 percent of
the time. In the second case RE is being used to address the failure of people to implement a rule
with the required vigor.
Applying an adjustment factor is a valid approach in each of these situations. Unfortunately, the
same term (RE) is used to describe and address both cases. The inventory community does not
need more jargon. However, a solution to the current dilemma is to abandon the RE name and
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replace it with two distinctive terms, each describing specifically the situation in which it applies.
Separate definitions should allow those interested in measuring how well a rule is achieving its
intended reductions to determine those results. Those interested in adjusting actual emission
estimates to compensate for upsets, downtime, etc could also meet their needs. Each new term is
described below.
The Practical Compliance Index (PCI) is to be used by those in policy positions to measure
how well a rule is achieving its intended results. The PCI is a measure of the extent to which a
rule actually accomplishes its desired emission reductions. For example, if a new rule has a PCI
of 80 percent, it has caused 80 percent of the needed emission reductions to occur. A
100 percent of the expected reductions did not (has not) occurred because not all facilities
implemented controls mandated by the rule, some facilities did not control at the emission rate
required by the rule, or unanticipated growth occurred in the area. Additionally, policy makers
using historical PCI values can develop realistic control strategies for their area.
The Operational Adjustment Factor (OAF) is to be used to adjust control efficiency ratings of
control devices. Adjustments are necessary due to control equipment down time, subpar control
device operations, and process upsets. Current methods of estimating emissions do not account
for these situations. The OAF will not be used to adjust emission factors, activity data, or direct
measurement of emissions.
How to Apply a PCI and an OAF
PCI
Air quality modeling is performed to support new rule development. Models are run to
determine how much pollutant should be removed from the air to reach an acceptable ambient air
quality concentration level. When the new rule is implemented, a strategy is developed, based on
model results, that describes the sources to be controlled and the acceptable emission rate of each
source.
The Practical Compliance Index (PCI) provides policy makers with two tools. The Index
measures how well the control strategy is progressing toward reaching the air quality goal. The
PCI is calculated by:
_ (Base Year Emission Estimate) - (Current Year Emission Estimate)
- (6)
Expected Reduction
The PCI measures progress toward meeting the new emission target in the designated attainment
year. PCI can be calculated periodically to provide policy makers with information on how the
policy is being implemented and the extent of compliance with new control requirements.
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Past experience has shown that, even if after a new rule is fully implemented, the ambient air
quality level still exceeds the standard. One reason for this failure is lack of compliance with a
new rule. Policy makers can use this information to increase the likelihood that future emission
targets will be met. This can be done by using an empirically derived factor is used to adjust
Equation 6. Even though the air quality modeling indicates a certain number of tons of pollutant
are needed to be removed to reach the standard, practical experience shows that, without
additional emphasis, this target will not be reached. The compensation factor in Equation 6a
offsets this lack of compliance. If the goal is to achieve a 100 percent PCI, then Equation 6
becomes:
n-^ _ Reduction Target x Compensation Factor
rLsi - (6a)
Expected Reduction
Where:
Compensation factor has a default value of 80 percent
The denominator is the amount of reduction necessary, as calculated by air quality modeling, to
achieve acceptable ambient air pollutant levels. By setting the PCI to 1 (100 percent) and solving
for the Reduction target in the numerator, policy makers will know how much pollutant reduction
should be targeted for their control strategies. The compensation factor is analogous to the
definition of RE in Equation 3. Guidance currently being used to calculate a RE factor can be
used to estimate the compensation factor in Equation 6a.
OAF
An inventory is composed of data that are used to estimate emissions. It contains information on
control efficiencies of the devices connected to the processes being inventoried. Actual
emissions are estimated either from direct measurements of the source or from calculations using
variables contained in the inventory. The most common approach to estimating emissions is to
select an emission factor associated with a process and combine it with the activity (thruput) of
the operations. This amount is adjusted by the control efficiency of the devices attached to the
process. The final product is an estimate of pollutant emitted to the atmosphere. Actual
emissions are calculated by:
Actual Emissions = (Emission Factor)mctl x (Activity Data) x (1 - Control Efficiency x OAF) (7)
There are several inaccuracies associated with this approach. Even though the precision of the
emission factor or activity estimate may be poor, there is usually no quantifiable bias associated
with these values. However, because of operational process upsets, down time of the control
device, and maintenance of the control equipment, overall control efficiency of the devices
attached to the process is not as great as stated by the manufacturers. This introduces a bias into
B-7
-------
the emission estimating process that is known qualitatively, but is not accounted for in the
inventory.
Equation 7 assumes there is no bias in the emission factor or activity data and that the control
device operates at 100 percent of its design efficiency all the time the process is running. To
reflect reality, control efficiency should be adjusted for process upsets and control device
downtime. Equation 7 then becomes:
Actual Emissions = (Emission Factor)mctl x (Activity Data) x (1 - Control Efficiency x OAF)
Where: OAF = 1 -
(Tons by-passing control device (tpy)
[Tons Collected (tpy)] + [Tons by-passing control device(tpy)]
The OAF is determined by examining operating records for a control device or family of devices.
The amount of time it is operating, the number of process upsets, and the quantity of pollutant
that bypasses the control device during these periods can be used to create the OAF.
Recently, some emission rates are being combined with process control efficiencies to form an
emission factor that consists of a process-control device combination. Equation 8a is used when
the emission factor incorporates control efficiency.
Actual Emissions = (Emission Factor)ctl x (Activity Data) x (1/CE - OAF) (ga)
Summary
The emission inventory community has been using RE for almost a decade. Even though the
term has been used interchangeably in totally different applications, the distinctions have been
poorly understood. New terminology proposed in this paper should correct this problem. The
PCI measures the degree to which a rule is being implemented (by measuring the amount of
actual reduction and comparing it to the expected reduction). It is based on historical results
from past rule implementation efforts or from recent surveys that indicate the degree of
compliance to be expected. The PCI compensates for the failure of people to fully implement a
rule.
The OAF is a function of control equipment efficiency, the adequacy of equipment maintenance,
equipment reliability, and the stability of a process. This information is available from records
maintained at each facility. The OAF compensates for the failure of equipment to perform at its
stated capacity.
B-8
-------
Next Steps
• Determine how this proposed approach affects existing data;
• Determine how existing guidance must be changed to reflect new approach;
• Decide what to do about previously reported data that has RE applied; and
• Develop new guidance explaining use of PCI and OAF.
References
1. Federal Register, Vol. 52, No. 226, Tuesday, November 24, 1987, p45059.
2. Federal Register, Vol. 57, No. 74, Part HI, Thursday, April 16, 1992.
3. "Guidelines for Estimating and Applying Rule Effectiveness for ozone/CO State
Implementation Plan Base year Inventories," November 1992, EPA-452/R-92-010
4. "Rule Effectiveness Guidance: Integration of Inventory, Compliance, and Assessment
Applications," January 1994, EPA-452/4-94-001.
5. "Developing Present and Future Year Emissions Inventories Using Rule Effectiveness
Factors", presented at the International Conference and course, Emission Inventory
Issues, Durham, NC, October 1992.
6. "Emission Inventories and Proper Use of Rule Effectiveness,"
http://www.epa.gov/ttn/chief/eiip/pointsrc.htm, draft report, October 1998.
B-9
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B-10
-------
APPENDIX C
LIST OF EIIP PREFERRED AND ALTERNATIVE METHODS
BY SOURCE CATEGORY
(Current as of August 1999)
-------
Contents
Table Page
1 List of EIIP Preferred and Alternative Methods by Source Category
(Point Sources) C-l
2 List of EIIP Preferred and Alternative Methods by Source Category
(Area Sources) C-4
C-ii
-------
This page is intentionally left blank.
C-iii
-------
Table 1. List of EIIP Preferred and Alternative Methods
by Source Category (Point Sources )
Source Category
Aircraft
Manufacturing,
Surface Coating
Appliances, Surface
Coating
Automobiles and
Light-duty Trucks,
Surface Coating
Automobile
Refmishing, Surface
Coating
Equipment Leaks
Flat Wood Product
Manufacturing,
Surface Coating
Heavy-duty Truck
Manufacturing,
Surface Coating
Hot-Mix Asphalt
Plants
Magnet Wire,
Surface Coating
Metal Cans, Surface
Coating
Estimation Methods, Preferred (P) or Alternative (A)
Material
Balance
P,A
P,A
P,A
P,A
P,A
P,A
P,A
P, A
Emission
Factors
A
A
A
A
A
A
A
P
A
A
Source
Testing
P, A
P,A
P,A
P,A
A
P,A
P,A
P
P,A
P,A
CEM
Data
A
Emission
Models/
Predictive
Monitoring41
A
A
A
A
P
A
A
A
A
A
Fuel
Analysis
P
Engineering
Calculations
C-l
-------
Table 1. List of EIIP Preferred and Alternative Methods
by Source Category (Point Sources ) (Continued)
Source Category
Metal Coil, Surface
Coating
Metal Furniture,
Surface Coating
Miscellaneous
Metal Parts, Surface
Coating
Oil & Gas Field
Production &
Processing
Paint and Ink
Manufacturing
Paper Coating,
Surface Coating
Plastic Products
Manufacturing
Plastic Parts,
Surface Coating
Secondary Metal
Processing
Semiconductor
Manufacturing
Ships, Surface
Coating
Wastewater
Collection and
Treatment
Estimation Methods, Preferred (P) or Alternative (A)
Material
Balance
P,A
P,A
P,A
A
P,A
P,A
P,A
P
P, A
A
Emission
Factors
A
A
A
P,A
P, A
A
A
A
P,A
A
A
A
Source
Testing
P, A
P,A
P,A
A
A
P,A
P, A
P,A
P, A
P,A
P,A
A
CEM
Data
A
P,A
Emission
Models/
Predictive
Monitoring41
A
A
A
P
P
A
A
A
A
P
Fuel
Analysis
Engineering
Calculations
A
A
C-2
-------
Table 1. List of EIIP Preferred and Alternative Methods
by Source Category (Point Sources ) (Continued)
Source Category
Wood Furniture,
Surface Coating
Estimation Methods, Preferred (P) or Alternative (A)
Material
Balance
P,A
Emission
Factors
A
Source
Testing
P, A
CEM
Data
Emission
Models/
Predictive
Monitoring41
A
Fuel
Analysis
Engineering
Calculations
a Predictive emission monitoring is an estimation method where emissions are correlated to process
parameters based on demonstrated correlations.
Reference: Emission Inventory Improvement Program Preferred and Alternative Methods. Volume I,
Introduction to the EIIP, and Volume n, Point Sources.
C-3
-------
Table 2. List of EIIP Preferred and Alternative Methods
by Source Category (Area Sources )
Source
Category
Architectural
Surface
Coating
Asphalt
Paving
Autobody
Refinishing
Consumer Solvents
Dry Cleaning
Gasoline
Distribution,
Stage I
Gasoline
Distribution,
Stage II
Graphic Arts
Industrial Surface
Coating
Landfills
Marine Vessel
Loading, Ballasting
and Transit
Estimation Methods, Preferred (P) or Alternative (A)
Survey
P
P,A
P
A
P
P, A
P
P
P
P
Material
Balance
P
P
P
P
Emission
Factors
A
P
P, A
P, A
P
Top-Down Approach
Per-employee or
Per-capita
Emission
Factors
A
A
P,A
A
A
P,A
A
Allocation
of National
Level
Activity
A
A
A
A
A
Emission
Estimation
Models
P, A
P, A
C-4
-------
Table 2. List of EIIP Preferred and Alternative Methods
by Source Category (Area Sources )(Continued)
Source
Category
Open Burning
Pesticide Use,
Agriculture
Pesticide Use,
Non Agriculture
(Municipal,
Commercial and
Consumer)
Residential
Wood Combustion
Solvent
Cleaning
Traffic Paints
Estimation Methods, Preferred (P) or Alternative (A)
Survey
P
P, A
P
P
P, A
P
Material
Balance
A
A
P
Emission
Factors
P
P, A
P,A
P
P,A
Top-Down Approach
Per-employee or
Per-capita
Emission
Factors
A
A
A
Allocation
of National
Level
Activity
A
A
A
Emission
Estimation
Models
Reference: Emission Inventory Improvement Program Preferred and Alternative Methods.
Volume HI, Area Sources.
C-5
-------
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C-6
-------
APPENDIX D
POINT SOURCES EXAMPLE CALCULATIONS
-------
Contents
Example Page
1 Coal-fired Industrial Boiler (Emission Factors and Temporal Allocation) ... D-l
2 Natural Gas and Number 6 Fuel Oil Fired Industrial Boiler
Emissions (Emission Factors) D-4
3 Copper Coil Manufacturing (Mass Balance) D-7
4 Paint Manufacturing (Source Test Data) D-9
5 Boiler Emissions (Source Test Data) D-10
6 Boiler Emissions (CEM Data) D-l 1
7 Boiler Emissions (Fuel Analysis) D-13
D-ii
-------
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tw\K:\010 UOPTIONl \011 \002\APPX-D. WPD
D-iii
-------
Example 1— Coal-fired Industrial Boiler (Emission Factors and Temporal
Allocation)
This example illustrates the procedures to calculate emissions from an industrial boiler
firing anthracite coal.
Assumed Operating Parameters
Coal type: Anthracite
Annual coal consumption: 928,000 tons per year (tpy)
Ash content of coal: 7 percent
Sulfur content of coal: 1.87 percent
Seasonal throughput fractions: Winter = 50%;
Spring = 20%;
Summer = 10%;
Fall = 20%
Particulate emissions are controlled with a 75 percent efficient cyclone
Sulfur oxides emissions are controlled with a 93 percent efficient limestone injection
system.
Boiler Type: Traveling grate stoker
AP-42 Emission Factors
Section 1.2 of AP-42 provides emission factors for pollutants from anthracite coal
combustion in stoker fired boilers:
Total organic compounds (TOC): = 0.3 Ib/ton (Table 1.2-6)
Particulate matter (PM): = 0.8A Ib/ton for PM-filterable and 0.08A Ib/ton
for PM-condensible where A is the ash content
of coal in weight percent (Table 1.2-3)
Lead(Pb): = 8.9E-03 Ib/ton (Table 1.2-3)
Nitrogen oxides (NOX): = 9 Ib/ton (Table 1.2-1)
Sulfur dioxide (SO2): = 39S Ib/ton where S is the weight percent of
sulfur in the coal (Table 1.2-1)
Carbon monoxide (CO): = 0.6 Ib/ton (Table 1.2-2)
D-l
-------
Example 1— Coal-fired Industrial Boiler (Emission Factors and Temporal
Allocation) (Continued)
Estimating Uncontrolled Emissions
The general equation for estimating uncontrolled emissions of TOC, Pb, NOX, CO,
and CO2 from anthracite coal combustion in boilers is as follows:
Boiler Emissions = Annual Coal Consumption x Emission Factor
TOC = 928,000 tons/year x 0.3 Ib/ton = 278,400 Ib/year = 139.2 tpy
Pb = 928,000 tons/year x 8.9E-03 Ib/ton = 8,259 Ib/year = 4.1 tpy
NOX = 928,000 tons/year x 9 Ib/ton = 8,352,000 Ib/year = 4,176 tpy
CO = 928,000 tons/year x 0.6 Ib/ton = 556,800 Ib/year = 278 tpy
The general equation for estimating uncontrolled emissions of PM from anthracite
coal combustion in boilers is as follows:
PM Emissions = Annual Coal Consumption x (Emission Factor x Coal Ash
Content)
PM-Filterable = 928,000 tons/year x (0.8 lb/.056 ton x .07) = 51,968 Ib/year
= 25.98 tpy
PM-Condensible = 928,000 tons/year x (0.08 lb/.0056 ton x .07) = 5196.80
Ib/year
= 2.598 tpy
Total PM = 25.98 tpy+ 2.598 tpy = 28.58 tpy
The general equation for estimating uncontrolled emissions of SO2 from anthracite
coal combustion in boilers is as follows:
SO2 Emissions = Annual Coal Consumptionx (Emission Factor x Coal
Sulfur Content)
SO2 = 928,000 tons/year x (39 Ib/ton x .0187) = 676,790.4 Ib/year
= 338.4 tpy
D-2
-------
Example 1— Coal-fired Industrial Boiler (Emission Factors and Temporal
Allocation) (Continued)
Estimating Controlled Emissions
Particulate emissions are controlled with a 75 percent efficient cyclone and SO2
emissions are controlled with a 93 percent efficient limestone injection system. The
general equation for estimating controlled emissions of PM and SO2 is as follows:
Controlled Emissions = Uncontrolled Emissions x (1 - Efficiency/100)
Total PM = 28.58 tpyx (1-75/100) = 28.58 tpyx (0.25) = 7.15 tpy
SO2 = 338.4 tpyx (1-93/100) = 338.4 tpyx (0.07) = 23.7 tpy
Temporal Allocation of PM Emissions
The general equation for estimating seasonal emissions is as follows:
Seasonal emissions = Seasonal throughput fraction x annual emissions
Therefore:
Winter emissions of PM = 0.5 x 7.15 tpy = 3.575 tons
Spring emissions of PM = 0.2 x 7.15 tpy = 1.43 tons
Summer emissions of PM = 0.1 x 7.15 tpy = 0.715 tons
Fall emissions of PM = 0.2 x 7.15 tpy = 1.43 tons
D-3
-------
Example 2—Natural Gas And Number 6 Fuel Oil Fired Industrial Boiler Emissions
(Emission Factors)
This example illustrates the use of AP-42 emissions factors to estimate emissions from a
small industrial boiler firing natural gas and Number 6 fuel oil.
Assumed Operating Parameters
Natural Gas
Annual Consumption: 99,885 MMBtu/year
Heating Value: 1,032 Btu/scf
Usage: 81% of the time
#6 Oil
Annual Consumption: 147,983 gal/year
Heating Value: 150,000 Btu/gal
Sulfur Content: 1 percent
Nitrogen Content: 0.4 percent
Usage: 19% of the time
AP-42 Emission Factors
Sections 1.3 and 1.4 of AP-42 provide emission factors for pollutants from industrial boilers
firing Number 6 fuel oil and natural gas, respectively.
Natural Gas
PM-Filterable: 1.9 lb/106 scf (Table 1.4-2)
PM-Condensible: 5.7 lb/106 scf (Table 1.4-2)
SOX: 0.6 lb/106 scf as SO2 (Table 1.4-2)
NOX asNO2: 100 lb/106 scf asNO2 (Table 1.4-1)
CO: 84 lb/106 scf (Table 1.4-1)
TOC: 11 lb/106 scf (Table 1.4-2)
Number 6 Fuel Oil
All emission factors for Number 6 fuel oil are obtained from Table 1.3-1 in AP-42 (except as
noted) for boilers with firing rate less than 100 million Btu/hr:
CO: 5 lb/103 gal
Nonmethane Volatile Organics: 0.28 lb/103 gal [Table 1.3-3]
Methane Volatile Organics: 1 lb/103 gal [Table 1.3-3]
NOX as NO2: [20.54 + (104.39 x N)] lb/103 where N is the weight
percent of nitrogen in the oil
NO2 emission factor = 20.54+ (104.39 x 0.4) = 62.3
lb/103 gal
D-4
-------
Example 2—Natural Gas And Number 6 Fuel Oil Fired Industrial Boiler Emissions
(Emission Factors) Continued
Paniculate Matter (PM): [9.19(S) + 3.22] lb/103 gal where S is the weight
percent of sulfur in the oil
PM emission factor = [9.19(1) + 3.22] lb/103 gal =
12.41 lb/103 gal
Sulfur Oxides as SO2: 157(S) lb/10 gal where S is the weight percent of
sulfur in the oil
SO2 emission factor = 157(1) = 157 lb/103 gal
Sulfur Oxides as SO3: 2(S) lb/10 gal where S is the weight percent of sulfur
in the oil
SO3 emission factor = 2(1) = 2 lb/103 gal
Estimating Uncontrolled Emissions by Fuel Type
Natural Gas
The general equation for estimating natural gas consumption in scf/year is as follows:
. , ^ .. Annual Heat Input
Annual Consumption = r
Natural Gas Heating Value
99,885 x 106 Btu/year _, _ 1ft6 _.
= — = 96.8 x 10° scf/year
1,032 Btu/scf
The general equation for estimating uncontrolled emissions from natural gas combustion is
as follows:
Natural Gas Emissions = Annual Gas Consumption x Emission Factor
PM-Filterable = 96.8xl06 scf/year x 1.9 lb/106 scf = 184 Ib/year = 0.09 tpy
PM-Condensible = 96.8xl06 scf/year x 5.7 lb/106 scf = 552 Ib/year = 0.28 tpy
SOX = 96.8xl06 scf/year x 0.6 lb/106 scf = 58 Ib/year = 0.03 tpy
NOX = 96.8xl06 scf/year x 100 lb/106 scf = 9,680 Ib/year = 4.8 tpy
CO = 96.8xl06 scf/year x 84 lb/106 scf = 8,132 Ib/year = 4.07 tpy
TOC = 96.8xl06 scf/year x 11 lb/106 scf = 1,064.8 Ib/year = 0.53 tpy
Total PM emissions from the combustion of natural gas is given by the following equation:
Total PM Emissions = PM-Filterable + PM-Condensible
0.09 tpy + 0.28 tpy = 0.37 tpy
D-5
-------
Example 2— Natural Gas And Number 6 Fuel Oil Fired Industrial Boiler Emissions
(Emission Factors) (Continued)
Number 6 Fuel Oil
The general equation for estimating uncontrolled emissions from Number 6 fuel oil
combustion in an industrial boiler is as follows:
Number 6 Fuel Oil Emissions = Annual Fuel Oil Consumption x Emission Factor
PM = 147,983 gal/year x 12.41 lb/103 gal =
1,836 lb/year = 0.92 tpy
SOX as SO2 = 147,983 gal/year x 157 lb/103 gal =
23,2331b/year= 11. 6 tpy
SOX as SO3 = 147,983 gal/year x 2 lb/103 gal = 296 Ib/year
= 0.15 tpy
NOX as NO2 = 147,983 gal/year x 62.3 lb/103 gal = 9,219
Ib/year = 4.6 tpy
CO = 147,983 gal/year x 5 lb/103 gal = 740 Ib/year
= 0.37 tpy
Nonmethane Volatile Organics = 147,983 gal/year x 0.28 lb/103 gal =
4 1.44 Ib/year = 0.021 tpy
Methane Volatile Organics = 147,983 gal/year x 1 lb/103 gal = 148 Ib/year
= 0.074 tpy
Total SOX emissions from the combustion of Number 6 fuel oil is given by the following
equation:
SOX Emissions = SO2 emissions + SO3 emissions = 11.6 + 0.15 = 11.75 tpy
Total Volatile Organic emissions from the combustion of Number 6 fuel oil is given by the
following equation:
Total Organic Emissions = Nonmethane Volatile Organics + Methane Volatile
Organics
0.021 tpy + 0.074 tpy = 0.095 tpy
Estimating Total Uncontrolled Emissions
Total Emissions = Natural Gas Emissions + Number 6 Fuel Oil Emissions
Total PM = 0.37 tpy + 0.92 tpy = 1 .29 tpy
Total SOX = 0.03 tpy + 1 1 .75 tpy = 1 1 .78 tpy
Total NOX = 4.8 tpy + 4.6 tpy = 9.4 tpy
Total CO = 4.07 tpy + 0.37 tpy = 4.44 tpy
D-6
-------
Example 3~Copper Coil Manufacturing (Mass Balance)
This example illustrates the use of material (mass) balances as a method for estimating
emissions from a metal rolling unit that processes copper coil. Prior to a rolling step,
copper coil is sprayed with oil for lubrication and heat dispersion. After rolling, the
copper coil is sent to an annealer which has been shown to destroy 85 percent of the oil
during the heat treatment of the copper coil. Negligible amounts of oil remain on the
copper coil after annealing. The oil is assumed to be 100 percent VOC. The VOC
emissions associated with this process occur from volatilization of lubricating oil during
its application prior to rolling as well as the undestructed oil exhausted from the annealer.
Assumed Operating Parameters
Mass of copper coil processed: 5,000 kg
Mass of copper coil and oil sent to annealer: 5,075 kg
Mass of lubricating oil sprayed onto the copper: 3,000 kg
Mass of lubricating oil recovered: 2,800 kg
Estimating Emissions
The general formula to complete a material balance is represented by:
Input + Generation - Output - Consumption = Accumulation
where:
Input: mass entering the process
Generation: mass produced in the process
Output: mass exiting the process
Consumption: mass consumed in the process
Accumulation: mass that builds up within the process
For this example, the parameters listed above are described as:
Input: mass of lubricating oil applied (3,000 kg)
Generation: not applicable/no material generation (0 kg)
Output: mass of oil lost as an emission
Consumption: mass of oil destroyed in the annealer
Accumulation: mass of lubricating oil recovered (2,800 kg)
The estimate for the Consumption parameter is calculated from the mass of copper coil
processed, the mass of copper coil and oil sent to the annealer, and the oil destruction
efficiency as it is exposed to high temperatures in the annealer.
Consumption = (mass of coil/oil to annealer - mass of coil processed) x 85 percent
= (5,075 kg - 5,000 kg) x 0.85
= 64 kg oil destroyed in the annealer
D-7
-------
Example 3~Copper Coil Manufacturing (Mass Balance) (Continued)
After simplifying the material balance formula, the estimate of the Output (emissions)
from this process is:
Input - Output - Consumption = Accumulation
Or:
Output = Input - Consumption - Accumulation
Output = 3,000 kg - 64 kg - 2,800 kg
Output = 136kg
The VOC emissions associated with this process are thus 136 kg oil per 5,000 kg of
copper coil processed, or 0.027 kg oil per kg of copper coil processed.
D-8
-------
Example 4~ Paint Manufacturing (Source Test Data)
This example illustrates the use of source test data to estimate process emissions from
a spray booth at a paint manufacturing facility. The materials emitted from the spray
booth stack are assumed to be 100 percent VOC.
Assumed Operating Parameters
Stack flow rate: 50,000 scm/hr
Average measured VOC concentration from stack: 0.005 kg VOC/scm
Spray booth annual operation: 2,080 hr/year
Estimating Emissions
Since the source testing provided a VOC concentration and the average stack exhaust
flow rate, the concentration can be converted to a mass flow rate:
Mass Flow rate = volumetric flow rate x concentration
= 50,000 scm/hr x 0.005 kg VOC/scm
= 250 kg VOC/hr
The annual VOC emissions can then be estimated using the mass flow rate and the
annual hours of operation for the paint spray booth:
Emissions = mass flow rate x annual hours operation
= 250 kg VOC/hr x 2,080 hr/yr
= 520,000 kg VOC/yr or 520 metric tons
D-9
-------
Example 5 ~ Boiler Emissions (Source Testing)
This example illustrates the procedure to estimate lead emissions from a boiler using
stack testing results.
Assumed Operating Parameters
The results of these stack sampling test runs show that the average concentration of
lead (Pb) in the stack gas is 0.0005 pound per dry standard cubic feet (Ib/dscf) and the
average stack gas volumetric flow rate is 51,700 dry standard cubic feet per minute
(dscf/min). The boiler operates 5,840 hours per year, and is equipped with a
multicyclone.
Calculating Pb Emissions
The Pb emission rate is calculated as follows:
Pb Emission Rate = Pb concentration x stack gas flow rate
= 0.0005 Ib/dscf x 51,700 dscf/min x 60 min/hr
= l,5511b/hr
Annual Pb Emissions = 1,551 Ib/hr x 5,840 hr/yr x 1 ton/2,000 Ib = 4,528 tpy
D-10
-------
Example 6~Boiler Emissions (CEM Data)
This example illustrates how average SO2 emissions can be calculated based on raw
CEM data.
Assumed Operating Parameters
Example CEM output for a boiler burning fuel oil is provided in the following table:
Period
11:00
11:15
11:30
11:45
12:00
Average
°2
(%V)
2.1
2.0
2.1
1.9
1.9
2.0
SO2
(ppmv)
1,004.0
1,100.0
1,050.0
1,070.0
1,070.0
1,058.8
Stack Gas Flow
Rate (dscfm)
155,087
155,943
155,087
154,122
156,123
155,272
HHV:
SO2:
V:
Qf
OpHrs:
Fuel heating value: 18,000 Btu/lb
Molecular weight: 64 Ib/lb-mole
Molar volume: 385.5 ft3/lb-mole at 68 °F and 1 atm
Mass fuel throughput: 46,000 Ib/hr
Total annual hours of operation: 5,400 hours
Calculating Hourly Emissions of SOo
"SO,
= (C x MW x Q x 60)
(V x 106)
Where:
C: Parts per million by volume dry air (ppmvd)
MW: Molecular weight in Ib/lb-mole
Q: Flow rate in dry standard cubic feet per minute (dscfm)
V: molar volume in cubic feet (ft )/lb-mole
D-ll
-------
Example 6~Boiler Emissions (CEM Data) (Continued)
1,058.8 x 64 x 155,272 x 60 , „_ „.
EQri = — = 1,637 Ib/hr
S°2 385.5 x 106
Calculating Heat Input
(Qf x HHV)
H. =
(106)
„ 46,000 x 18,000 000 A/rA/ro, „
H. = —'- '- = 828 MMBtu/hr
106
Developing SOo Emission factors
An SO2 emission factor expressed as Ib/MMBtu is calculated as follows:
__ ^802 1,637 Ib/hr 1 __ 1u/1./r,/mi
EFQri = - - = - '- - = 1.98 Ib/MMBtu
s°2 H 828 MMBtu/hr
Calculating Annual SOo Emissions
Annual SO2 Emissions = hourly SO2emissions x OpHrs
(1,637 Ib/hr x 5,400 hrs)
= -^ = 4,419 tons per year
(2,000 Ib/ton)
D-12
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Example 7~Boiler Emissions (Fuel Analysis)
This example illustrates how SO2 emissions from fuel combustion can be calculated
using fuel analysis results.
Assumed Operating Parameters
Sulfur content of fuel: 1 % by weight
Fuel throughput: 5,000 Ib/hr
Hours of operation: 8,760 hours/year
Calculating SO2 emissions:
The basic equation in fuel analysis emission calculation is:
E = Qf x pollutant concentration in fuel x (Mw /MWf)
Where:
Qf = Throughput of fuel in Ib/hr
MW = Molecular weight of pollutant emitted (Ib/lb-mole)
MWf = Molecular weight of pollutant in fuel (Ib/lb-mole)
In this example, MW = 32 + (16 x 2) = 64 Ib/lb-mole
MWf = 32 Ib/lb-mole
Therefore, Eso = 5,000 Ib/hr x 0.01 x (64/32)
= 100 Ib/hr
1 ton
100 Ib/hr x 8,760 hr/yr x
2,000 Ibs
= 438 tons/year of SO,
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APPENDIX E
AREA SOURCES EXAMPLE CALCULATIONS
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Contents
Example Page
1 Surface Coating (Mass Balance) E-l
2 Emissions from Benzene Loading Operations (Emission Factor) E-2
3 Cold Cleaners Solvent Degreasing (Emission Factors) E-4
4 Process Cooling Tower (Actual and Allowable Emissions) E-6
5 Estimating County Level Wood Usage (Top-Down Approach) E-8
6 Open Burning of Household Waste (Local Survey Results) E-9
7 Surface Coating (Per Employee Emission Factor) E-l 1
8 Vapor Degreaser (Material Balance) E-12
9 Agricultural Burning (Extrapolation/Top-Down) E-l3
10 Stage I Gasoline Marketing (Rule Effectiveness/Rule Penetration) E-l4
11 Architectural Surface Coating (Per-Capita Emission Factor) E-l5
12 Unpaved Roads (Empirical Equation/Computer Software) E-l6
13 Estimating Seasonal Wood Consumption (Temporal Allocation) E-l8
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E-iii
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Example I—Surface Coating Operations (Mass Balance)
This example illustrates the procedures to calculate VOC and PM emissions from
surface coating operation at a wood furniture plant.
Assumed Operating Parameters
Coating Type: A
Coating Density: 7.5 Ib/gal as applied
Coating Density of Volatile Content: 6.2 Ibs/gallons as applied
Coating Usage: 1,600 gallons per year
Spray Booth Type: Dry-filler spray booth
Spray Gun Transfer Efficiency: 60%
Dry Filter Collection Efficiency: 99%
Estimating VOC Emissions
VOC (tpy) = Volatile content density x annual usage
6.2 Ibs/gal x 1,600 gal/yr = 9,920 Ib/yr
9,920 Ib/yr x 1 ton/2,000 Ibs = 4.96 tpy
Estimating Uncontrolled PM Emissions
Coating density of solid content = Density of coating A - Density of volatile
content
= 7.5 Ib/gal - 6.2 Ib/gal = 1.3 Ib solids/gal
Uncontrolled PM emissions = Density of solid content x annual usage
x (1 - transfer efficiency)
= 1.3 Ib/gal x 1,600 gal/yr x (1 - 0.6)
= 832 Ib/yr or 0.416 tpy
Estimating Controlled PM Emissions
Controlled PM emissions = Uncontrolled PM x (1 - Control efficiency)
= 0.416 x (1 - 99/100) = 0.00416 tpy of solids
E-l
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Example 2~ Emissions from Benzene Loading Operations (Emission Factor)
This example illustrates the AP-42 calculation procedures, at a benzene
manufacturing facility, for estimating emissions from transfer of benzene using
dedicated, submerged loading transfer trucks equipped with condensers for product
recovery.
Assumed Operating Parameters
Transfer truck volume: 9,200 gals
Benzene loading temperature: 80°F
Vapor recovery efficiency: 95 percent
Annual benzene loaded: 820,000 gals
AP-42 Emission Factors
Emissions from uncontrolled loading operations can be estimated using the following
AP-42 equation obtained from Section 5.2 of AP-42:
LL = 12.46 x S x P x M/T
where:
LL = loading loss, in lb/103 gal of liquid loaded
M = molecular weight of vapors, in Ib/lb-mole, obtained from Table 7.1-2
P = true vapor pressure of liquid loaded, in psia, obtained from Table 7.1-2
T = temperature of bulk liquid loaded, in °R (°F + 460)
S = saturation factor, obtained from Table 5.2-1 and function of cargo carrier
and mode of operation
From Table 7.1-2, M =78 Ibs/lbs-mole
From Table 7.1-2, P =2 psia
T = 80°F = 80°F + 460 = 540°R
From Table 5.2-1, for a submerged loading, dedicated, normal service operations,
S = 0.6
Based on the above, the emission factor for benzene loading operations is
0.6 x 2 psia x 78 lb
LT (lb/103 gal) = 12.46 x lb mole = 2.161b benzene/l,000gal
L 5 540°R
E-2
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Example 2~ Emissions from Benzene Loading Operations (Emission Factor)
(Continued)
Estimating Uncontrolled PM Emissions
The general equation for estimating uncontrolled emissions from benzene loading
operations is as follows:
Uncontrolled Emissions = Quantity of Benzene Loaded x Emission Factor
Uncontrolled Emissions = 820,000 gal/year x 2.16 lb/1,000 gal = 1,771 Ib/year = 0.9 tpy
Estimating Emissions After Control
Emissions from controlled loading operations can be calculated by multiplying the
uncontrolled emission rate by the control efficiency:
Emission After Control = Uncontrolled Emissions x (1 - eff/100)
Emissions After Control = 0.9 tpy x (1-95/100) = 0.045 tpy = 90 Ib/year
E-3
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Example 3~ Cold Cleaners Solvent Degreasing (Emission Factors)
This example illustrates the calculation procedures required to estimate emissions
from a solvent degreasing process using cold cleaners. Uncontrolled emissions from
cold cleaners occur through waste solvent evaporation, solvent carryout, solvent bath,
and spray evaporation.
Assumed Operating Parameters
Number of degreasing units: 5 units
Volume of virgin solvent use: 120 tpy
AP-42 Emission Factors
From AP-42 Table 4.6-2, VOC emissions are calculated using the following emission
factors:
Waste solvent loss = 0.18tpy/unit
Solvent carryout = 0.08 tpy/unit
Bath and spray evaporation = 0.07 tpy/unit
Estimating Emissions
The general equation for estimating VOC emissions from a solvent degreasing process
is as follows:
VOC Emissions = Waste Solvent Losses + Solvent Carryout + Bath and Spray Evaporation
Waste solvent losses = solvent losses factor x number of units in operation
= 0.18x5 = 0.9tpy
Solvent carryout = solvent carryout factor x number of units in
operation
= 0.08x5 = 0.4tpy
Bath and spray evaporation = bath and spray evaporation factor x number of units
= 0.07 x 5 = 0.4 tpy
VOC emissions = 0.9 ton/year + 0.4 ton/year + 0.35 ton/year = 1.65 tpy
E-4
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Example 3~ Cold Cleaners Solvent Degreasing (Emission Factors) (Continued)
The general equation for estimating TCA emissions from the solvent degreasing process
is as follows:
TCA Emissions = TCA Factor x Volume of Solvent Used
TCA Emissions = 1,920 Ib/ton x 120 tpy
= 230,400 Ib/year
= 115tpy
E-5
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Example 4~ Process Cooling Tower (Actual and Allowable Emissions)
This example illustrates the procedures to calculate PM10 emissions (both actual and
allowable) using AP-42 emission factors.
Assumed Operating Parameters
Cooling tower type: Wet with induced draft
Average cooling tower throughput rate in the past 3 years: 6,800 gallons per minute
(gpm)
Average Total Dissolved Solids (TDS) concentration in the past 3 years: 2,000 ppm
Actual hours of operation in 1998: 8,424 hours
Number of cells: 8
From operating permit, the following information was obtained:
Maximum number of hours of operation: 8,760 hr
Maximum TDS concentration permitted: 2,700 ppm
Estimating Actual Emissions
From AP-42 Table 13.4-1, the total liquid drift (TLD) is 1.7 lb/1,000 gal or
0.0017 Ib/gal:
Uncontrolled Actual PM10 emissions are calculated as follows:
PM10 (Ib/hr) = TLD (Ib/gal) x [TDS (ppm) x 1 (Ib TDS/106 Ib water] x throughput
(gpm) x 60 min/hr
= 0.0017 Ib/gal x 2,000 x 1/106 x 6,800 gpm x 60 min/hr
= 1.38721bPM10/hr
Actual hours of operation = 8,424 hr/yr
Therefore, uncontrolled PM10 emissions = 1.3872 x 8,424
= ll,6861b/yr
Total uncontrolled PM10 emissions from all 8 cells:
8 x 11,686 Ib/yr x 1 ton/2,000 Ib = 46.74 tpy
Estimating PM1Q Allowable Emissions
Uncontrolled allowable PM10 emissions are calculated as follows:
PM10 (Ib/hr) = TLD x [Max TDS] x throughput
= 0.0017 Ib/gal x 2,700 x 1/106 x 6,800 gpm x 60 min/hr
= 1.87271bPM10/hr
E-6
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Example 4~ Process Cooling Tower (Actual and Allowable Emissions)
(Continued)
Maximum hours of operation: 8,760
Therefore, uncontrolled allowable PM10 emissions is:
1.8727 Ib/hr x 8,760 hr/yr = 16,405 Ib/yr
Total allowable uncontrolled PM10 emissions from all 8 cells:
8 x 16,405 Ib/yr x 1 ton/2,000 Ib = 65.62 tpy of PM
10
E-7
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Example 5~ Estimating County Level Wood Usage (Top-Down approach)
This example illustrates the procedure to allocate residential wood consumption to the
county level using a top-down approach.
Assumed Operating Parameters
Wood used for residential energy in State A: 622,000 cords
(Obtained from the EIA' s State Energy Data Report)
Number of households using wood as primary fuel in State A: 80,047
(Obtained from the U.S. Census data on house heating fuel)
Number of households using wood as primary fuel in county of study:
1,242 households
Allocating Wood Used to the County of Study
County Wood Use = State wood use x county households/state households
= 622,000 x 1,242/80,047 = 9,651 cords burned in county of
study
E-8
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Example 6~ Open Burning of Household Waste (Local Survey Results)
This example illustrates the procedure to scale up the results of a survey performed on
a sample of households to estimate emissions from the entire county.
Assumed Operating Parameters
A survey of 200 households in a rural portion of County A showed that 6.7% of the
households use burn barrels to dispose of combustible household waste. The survey
was conducted in locations where no garbage pickup services are available. The
survey also showed that:
- The average waste generated per household is 6.75 Ib/day
- The waste generated that is combustible waste is 80%
The U.S. Census data also shows that 17,502 households are in the rural portion of
County A. A telephone conversation with the County Planning Department revealed
that 15% of the households in rural areas have access to public or private garbage
pickup services.
Scaling up Survey Results
A number of households in rural areas with no access to garbage pickup service =
17,502 x 0.85 = 14,877 households
Number of households that use burn barrels = 14,877 households x 6.7/100 =
997 households
Estimating Activity Level in County (Combustible Wasted
Total waste generated by households that use burn barrels:
997 households x 6.75 Ib/household/day = 6,730 Ib/day
Total combustible waste generated by households that use burn barrels:
6,730 Ib/day x 80/100 = 5,384 Ib/day
Estimating Emissions
Total combustible waste generated = 5,384 Ib/day = 2.69 ton/day
E-9
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Example 6~ Open Burning of Household Waste (Local Survey Results)
(Continued)
From AP-42, Table 2.5-1, the emission factors for open burning of municipal refuse
are:
CO: 85 Ib/ton
PM: 16 Ib/ton
SOX: 1 Ib/ton
NOX: 6 Ib/ton
TOC: 21.5 Ib/ton
Therefore, daily emissions from open burning of household waste in the County are:
CO: 85 Ib/ton x 2.69 tons/day = 228.6 Ib of CO/day
PM: 16 Ib/ton x 2.69 tons/day = 43.03 Ib of PM/day
SOX: 1 Ib/ton x 2.69 tons/day = 2.69 Ib of SOx/day
NOX: 6 Ib/ton x 2.69 tons/day =16.14 Ib of NOx/day
TOC: 21.5 Ib/ton x 2.69 tons/day = 57.84 Ib of TOC/day
TOC = Total organic compound
E-10
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Example 7— Surface Coating (Per Employee Emission Factor)
This example illustrates the procedure to estimate VOC emissions from surface
coating using a per-employee emission factor.
Assumed Operating Parameters
A survey was conducted on a subset of facilities that manufacture wood furniture. The
survey indicated that the average coating usage per employee is 12 gal/year. In
addition, the survey results indicate that the average coating applied has a density of
7.5 Ib/gal and is 45% VOC by weight.
Calculating Area Sources Employment (Adjusting for Major Sources^
Surface coating operations occur at facilities designated as point sources and at smaller
facilities designated as area sources. However, in order to avoid double counting,
emissions from those facilities that are designated as point sources should not be
included in the area source inventory. One approach to reducing the effect of double
counting is to subtract the activity occurring at the point sources. Therefore, in this
example, total employment in surface coating in the inventory is reduced by the
employment at the point sources. The resulting employment is assumed to be the
employment at area sources involved in surface coating operations.
Area source employment = total employment from County Business Patterns - major
source employment from permit applications = 2,500 - 1,600 = 900 employees
Calculating area source emissions
VOC emissions from area sources
area source employment x average
coating usage x % VOC x coating density
900 employees x 12 gal/yr x 7.5 Ib/gal
x 45/100
36,450 Ib/yr
18.23tpyofVOC
E-ll
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Example 8~ Vapor Degreaser (Material Balance)
This example illustrates the procedure to estimate VOC emissions from an open-top
vapor degreaser using a material balance approach.
Assumed Operating Parameters
At the beginning of each month, 50 gallons of solvent (density: 12.5 Ib/gal) are added
to the degreaser. During the month, an additional 10 gallons are added to replenish
losses. At the end of the month, 50 gallons of waste solvent are sent to a recycling
off-site. About 0.5 Ib of solid waste is collected for disposal. The solvent is 100%
VOC, the waste solvent is 98% VOC, and the solid waste is 5% VOC.
Calculating Solvent Used Per Month
Qm = (50 gal/month + 10 gal/month) x 12.5 Ib/gal
= 750 Ib/month
Calculating Waste Solvent Generated Per Month
Qout = gallons of solvent sent to recycling x solvent density x waste solvent x
VOC content + solid waste x solid waste VOC content
Qout = (50 gal/month x 12.5 Ib/gal x 0.98) + (0.5 Ib/month x 0.05)
= 612.5 Ib/month + 0.025 Ib/month
= 612.525 Ib/month
Estimating Emissions
Evoc = Qin'Qout = 750 Ib/month-612.525 Ib/month
137.5 Ib/month
E-12
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Example 9~ Agricultural Burning (Extrapolation/Top-Down)
This example illustrates the use of activity data from one State A to estimate emissions
from agricultural burning in a county in an adjacent State B of comparable agricultural
conditions (i.e., similar crops, agricultural methods, climate, etc.).
Assumed Operating Parameters
• Annual VOC emissions from agricultural burning in States: 200 tons per year
• Agricultural land use in State A: 100 acres
• Agricultural land use in State B: 70 acres
• Agricultural land use in County of Study in State B: 10 acres
Extrapolating Emissions from State A to State B
VOC in State B = VOC in State A x Acres in State B/Acres in State A
= 200tpyx70/100= 140 tpy
Calculating Emissions in County of Study
Using a top-down approach, VOC emissions in county of study are calculated as
follows:
VOCCounty = VOCState B x Area in County/Area of State B
VOCCounty = 140 tpy x 10 acres/70 acres
20 tpy
E-13
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Example 10— Stage I Gasoline Marketing (Rule Effectiveness/Rule Penetration)
This example illustrates the application of rule effectiveness and rule penetration in
calculating VOC emissions from filling an underground gasoline storage tank.
Assumed Operating Parameters
• Total county throughput: 500,000 gal/day
• Tank filling method: slash filling
• Filling method central efficiency: 95%
• Stage I gasoline marketing emission factors: 11.5 lb/1,000 gal throughput
(from AP-42, Table 5.2-7)
• RE is assumed to be 80%
• RP is assumed to be 93% (fraction of throughput that will be subject to
control)
Calculating Emissions
E = AxEFx(l-CxRExRP)
A = 500,000 gal/day
EF = 11.5 lb/1,000 gal
C = 0.95
RE = 0.8
RP = 0.93
Therefore, E = 500 x 11.5 x [1 - (0.95) (0.8) (0.93)]
= l,6851bofVOC/day
E-14
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Example 11 — Architectural Surface Coating (Per-Capita Emission Factor)
This example illustrates how a national per-capita emission factor can be developed
and applied to a county in order to determine emissions from architectural surface
coating.
Assumed Operating Parameters
Data on Paints and Allied Products from the Census indicate that 600,000,000 gallons
of paints were applied. An analysis of the data shows that 75% of the paints were
water-based. The U.S. population is assumed to be 250,000,000. Population in the
County of Study is 450,000.
Developing National Per-Capita Emission Factors
For solvent-based paints, the national per capita emission factor is:
600,000,000 x (1 - 0.75) . , ,, ,
= 0.6 gal/person/year
250,000,000
For water-based paints, the national per capita emission factor is:
600,000,000 x 0.75) , 0 ,, ,
= 1.8 gal/person/year
250,000,000
Estimating County-Level Emissions
Emissions at the county level are calculated as follows:
E = EF x county population
For solvent-based paints:
Esolvent = °-6 gal/person x 450,000 person = 270,000 gal/yr
For water-based paints:
Ewater = 1-8 gal/person x 450,000 persons = 810,000 gal/yr
E-15
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Example 12 ~ Unpaved Roads (Empirical Equation/Computer Software)
This example illustrates the use of an empirical expression to estimate the quantity of
PM2 5 and PM10 emission from an unpaved road. Alternatively, this example could
have been illustrated using the MECH model.
Assumed Operating Parameters
Unpaved road type: Publicly accessible road
Surface material: Dirt
Mean vehicle weight (W): 2.2 tons (default from AP-42, Section 13.2.2)
Vehicle miles traveled: 2.4 x 10 miles per year
Assigning Values to Variables in Empirical Expression
The size-specific emission factor is calculated as follows:
b
- [(365 - p)/365]
where:
k = constant
s = silt content of the unpaved road
a = constant
b = constant
c = constant
W = mean vehicle weight in tons
M = surface material moisture content under dry, uncontrolled conditions
p = number of days with at least 0.01 in of precipitation per year
From AP-42, the following values can be assigned to the variables listed above:
s =11 (Table 13.2.2-1 for a publicly accessible dirt road)
k = 0.38 Ib/VMT for PM2 5 (Table 13.2.2.-2)
k = 2.6 Ib/VMT for PM10 (Table 13.2.2-2)
a = 0.8 for PM2 5 and PM10 (Table 13.2.2-2)
b = 0.4 for PM2 5 and PM10 (Table 13.2.2-2)
c = 0.3 forPM25 andPM10 (Table 13.2.2-2)
W = 2.2 tons (default value recommended in Section 13.2.2 of AP-42)
Mdiy = 0.2% (default value recommended in Section 13.2.2 of AP-42)
p = 0.60 (Figure 13.2.2-1 for a county in Arizona)
E-16
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Example 12 ~ Unpaved Roads (Empirical Equation/Computer Software)
(Continued)
Calculating PMo 5 and PM1Q emission factors
™
= 0.38
ii r-8 2.2 Y
(12) ( 3 J
(0.2/0.2)03
"365 - 60 '
365
= 0.26 Ib/VMT
Calculating Annual Emissions
FF —
Annual emissions
PM2 5 emissions
PMjQ emissions
up8 2.2 Y
M I 3 J [365 -60]
- 1 7Q 1KA/A/TT
(0.2/0.2)03 [ 365 J
= EF x VMT x 1 ton/2,000 Ib
= 0.2616 x 2.4 x 106x 1/2,000 = 313.92 ton per year
= 1.79x2.4x 106x 1/2,000 = 2, 148 ton per year
E-17
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Example 13 ~ Estimating Seasonal Wood Consumption (Temporal Allocation)
This example illustrates the use of meteorological data to temporally allocate
residential wood burning activity to the inventory period. Annual activity data is
apportioned using the number of heating degree days that occur annually and during
the winter wood-burning season in the inventory area. This information can be
obtained from state climatological offices, airport meteorological stations, or National
Oceanographic and Atmospheric Administration (NOAA) climate data.
Assumed Operating Parameters
Annual Wood Consumption for Space Heating: 100,000 tons wood
Number of Heating Degree Days (HDD) During the Inventory Period: 1800
Number of Annual Heating Degree Days (HDD): 2430 days
Developing an Apportionment Factor
Seasonal Apportionment Factor (SAP) = (HDD in Season/Annual HDD)
SAF= (1800/2430)
SAF= 0.74
Estimating Seasonal Fuel Consumption
Seasonal Wood Consumption = Annual Wood Consumption x SAP
Seasonal Wood Consumption = 100,000 tons wood x 0.74
= 74,000 tons wood consumed during the inventory
period
E-18
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APPENDIX F
OVERVIEW OF REFERENCE MATERIALS
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Contents
Section Page
AIRS Facility Subsystem (AFS) F-l
AIRSWeb F-l
The NET Database F-2
Toxic Release Inventory F-3
Industry Sector Notebooks F-3
Integrated Data for Enforcement Analysis F-5
Economic Growth Analysis System F-6
Multiple Projections System (MPS) F-6
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F-iii
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AIRS Facility Subsystem (AFS)
The Aerometric Information Retrieval System (AIRS) is a computer-based system for the storage
and retrieval of ambient air quality monitoring data and emissions and compliance data for
individual facilities. Emissions data in the Airs Facility Subsystem (AFS) are used primarily by
states in the preparation of State Implementation Plans (SIPs) and SIP inventories. Types of data
stored in AFS include:
• Facility name, location, and SIC code;
• Stack parameters;
• Process-specific operating schedule;
SCC codes;
• Annual process rate, and fuel parameters; and
• Annual emissions estimates for criteria pollutants.
The AIRS database resides on EPA's mainframe computer system and is not a publicly available
database that can be accessed from the Web, but AFS data is publicly on EPA's Envirofacts at
http://www.epa.gov/enviro/indexjava.html. In addition, some source data are available on AIRS
TTN at http://www.epa.gov/airsdata/sources.html. In order to retrieve information directly from
AIRS, you need to obtain an account on the EPA mainframe computer system and pay the
applicable computer usage charges. Information about obtaining a computer account is available
by calling 1-800-334-2405 (toll free) or 919-541-7862 or can be obtained from NTIS at
(703) 605-6000.
As of the time this document was prepared, the emissions component of AFS is scheduled to be
discontinued in September, 2000 and the emissions data of AFS transferred to the NET. You
should consult the AIRS/AFS Web site at http://www.epa.gov/ttn/airs/afs/index.html for the
latest memos and information on the plans to migrate the emission component of AIRS/AFS to
the NET database.
AIRSWeb
The AIRSWeb gives access to air pollution data for the entire United States. AIRSWeb is a
collection of the most significant AIRS data elements. AIRSWeb "Source Reports" display
estimates of annual emissions of criteria pollutants from individual point sources, and number of
F-l
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sources and total pollutant emissions by industry. Specifically, there are six Source Reports that
can be generated from AIRSWeb:
• Ranking: Lists each source in order of its pollutant emissions, ranking them from
largest to smallest;
• Compliance: Indicates whether each source is complying with regulations
governing air pollutant emissions;
• Address: The name and address of each source plus additional descriptive
information;
• Count: The number of sources and total air pollutant emissions for each
geographic area (county, state, or EPA region);
• SIC: The number of sources and total air pollutant emissions for each SIC; and
• Year: The number of sources that submitted emissions estimates for each
calendar year (indicates how recent are the data).
AIRSWeb data collection is refreshed monthly, usually on the first Tuesday. AIRSWeb reports
can be accessed on the World Wide Web at http://www.epa.gov/airsweb/sources.htm.
The NET Database
The National Emissions Trends (NET) system is a national repository database compiled by
EPA. The NET blends state and local-supplied data with the EPA-derived data to form a
comprehensive national inventory of criteria and toxic pollutants. Estimates are added to the
inventory each year, with increasing levels of detail in the more recent years. As a result, the
NET reflects the latest information available. For example, the 1996 NET inventory includes
state-submitted inventory data generated for the Ozone Transport Assessment Group (OTAG)
and Grand Canyon Visibility Transport Commissions (GCVTC) and other inventory services.
The NET inventory does not necessarily include state data for any particular source or pollutant.
However, in the 1996 NET inventory, EPA intends to provide statewide emissions inventory data
on a county level basis to every state in the country.
The NET inventory can be used as a starting point in compiling an emissions inventory because it
can be used to compile an initial list of emission sources in the area of study for point and area
sources. Additional information on the NET inventory can be obtained through the EFIG's
Emissions Inventory Web site or from the Info CHIEF
Help Desk.
F-2
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Toxic Release Inventory
The EPA's Toxic Release Inventory (TRI) is a compilation of information about toxic chemicals
used, manufactured, stored, treated, transported, or released into the environment. EPA stores
TRI data in the Toxics Release Inventory System (TRIS). TRI data can be used in compiling a
list of emission sources in the area of study. However, TRI data are best used when combined
with information from other sources because of the following limitations associated with the TRI
data:
• TRI covers only a subset of industrial sources. Non-industrial sources such as dry
cleaners or automobile service stations are not covered in TRI;
• Many point sources may not be required to report data to TRIS. Facilities must
meet all of the following criteria in order to report data to TRIS;
Facilities that conduct manufacturing operations with SIC codes
20 through 39;
Facilities that have 10 or more full-time employees or their equivalent;
Facilities that manufacture, process, or otherwise use EPCRA
Section 313 chemicals at the following thresholds: 25,000 Ib/yr for
manufacturing and processing, or 100,000 Ib/yr otherwise used.
TRI can be searched by SIC, facility name, or location. TRI reports are available in public
libraries or can be downloaded off the World Wide Web at
http://www.epa.gov/opptintr/tri/access.htm. The TRI database can also be searched online
through the Right-To-Know Network (RTK NET) at
http://www. rtk. net/www/data/data gen. html.
Industry Sector Notebooks
The EPA's Office of Compliance has developed a series of profiles or notebooks containing
information on selected major industrial groups. Each sector-specific notebook brings
comprehensive details that include:
• Industrial process information;
• A comprehensive environmental profile;
• Pollutant release data;
• Contact names;
F-3
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• Compliane/enforcement history; and
• Bibliographic references.
The following Industry Sector Notebooks are currently available:
• Profile of the Aerospace Industry;
• Profile of the Air Transportation Industry;
• Profile of the Dry Cleaning Industry;
• Profile of the Electronics and Computer Industry;
• Profile of the Fossil Fuel Electric Power Generation Industry;
• Profile of the Ground Transportation Industry;
• Profile of the Inorganic Chemical Industry;
• Profile of the Iron and Steel Industry;
• Profile of the Lumber and Wood Products Industry;
• Profile of the Metal Casting Industry;
• Profile of the Metal Fabrication Industry;
• Profile of the Metal Mining Industry;
• Profile of the Motor Vehicle Assembly Industry;
• Profile of the Nonferrous Metals Industry;
• Profile of the Non-Fuel, Non-Metal Mining Industry;
• Profile of the Organic Chemical Industry;
• Profile of the Petroleum Refining Industry;
• Profile of the Pharmaceutical Industry;
• Profile of the Plastic Resins and Man-made Fibers Industry;
F-4
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• Profile of the Printing Industry;
• Profile of the Pulp and Paper Industry;
• Profile of the Rubber and Plastic Industry;
• Profile of the Shipbuilding and Repair Industry;
• Profile of the Stone, Clay, Glass and Concrete Industry;
• Profile of the Textiles Industry;
• Profile of the Transportation Equipment Cleaning Industry;
• Profile of the Water Transportation Industry; and
• Profile of the Wood Furniture and Fixtures Industry.
In addition, the Office of Compliance is planning to add new profiles to the Industry Sector
Notebook Series. Copies of the Notebooks can be downloaded from EPA's Web page at
http://es.epa.gov/oeca/sector/index.html. Printed bound copies of the notebooks can be ordered
from GPO at (202) 512-1800. Some of the electronic files of the notebooks published in 1995 do
not contain all the tables, graphs, charts, and illustrations that appear in the printed versions.
Integrated Data for Enforcement Analysis
The Integrated Data for Enforcement Analysis (IDEA) is an interactive data retrieval and
integration system developed by EPA's Office of Enforcement and Compliance Assurance
(OECA). IDEA integrates facility data across EPA's various program office databases. IDEA
can be used to:
• Produce the compliance history on a specific facility;
• Retrieve data for performing multimedia analysis of regulated facilities;
• Identify a group of facilities that meet a user's specific criteria; and
• Produce aggregated data on selected industries.
IDEA allows the user to search by facility location, pollutants emitted, and by SIC. It integrates
data from 17 databases including Aerometric Information and Retrieval System (AIRS)/AIRS
Facility Subsystem (AFS); Comprehensive Environmental Response, Compensation and
F-5
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Liability (CERCLA) Information System (CERCLIS); the 1990 Census of Population and
Housing; Dun & Bradstreet (DUNS); and TRI. IDEA resides on EPA's mainframe computer
located at the National Computer Center in Research Triangle Park, NC. Additional information
on IDEA can be found on OECA's Web page at http://es.epa.gov/oeca/idea/.
Economic Growth Analysis System
The Economic Growth Analysis System (EGAS) is an economic and activity forecasting model
that projects growth factors by source classification code (SCC) for nonattainment areas and
attainment portions of States for the 48 contiguous States. The system is composed of a national
economic tier, a regional economic tier, and a growth factor tier which includes energy
consumption models for the residential, commercial, and industrial sectors, modules which
forecast industrial physical output and vehicle miles traveled, and a crosswalk which matches the
appropriate growth factor with each point, area, and mobile source SCC. Additional information
on EGAS can be found at http://www.epa.gov/ttn/chief/ei data.html#EGAS
Multiple Projections System
The Multiple Projections System (MPS) is a projection model that uses a base year inventory,
source-specific growth factors, and projected changes in (source-specific) control efficiency and
rule effectiveness to develop inventories for future years. Additional information on MPS can be
found at http://www.epa.gov/ttn/chief/ei data.html#PS
F-6
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APPENDIX G
LIST OF EMISSION ESTIMATION MODELS
AND EMISSION FACTOR RESOURCES
(Current as of August 1999)
-------
Contents
Section Page
Landfill Gas Emissions Model G-l
TANKS G-l
WATERS G-l
CHEMDAT8 G-2
MECH G-2
PM Calc G-3
Compilation of Air Pollutant Emission Factors (AP-42) G-3
Factor Information Retrieval System (FIRE) G-4
Air Clearinghouse for Inventories and Emission Factors (Air CHIEF) CD-ROM G-4
G-ii
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G-iii
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List of Emission Factor Resources
Landfill Gas Emissions Model (Version 2.01)
The Landfill Gas Emissions Model was developed by the Clean Air Technology Center (CATC).
The model can be used to estimate emission rates for methane, carbon dioxide, nonmethane
organic compounds, and individual toxic air pollutants from landfills. The system allows the
user to enter specific information regarding the characteristics and capacity of an individual
landfill and to project the emissions of methane, CO, nonmethane organic compounds, and
individual HAPs over time using the Scholl Canyon decay model for landfill gas production
estimation. The Scholl Canyon Model is a first-order decay equation that uses site-specific
characteristics for estimating the gas generation rate. In the absence of site-specific data, the
program provides conservative default values. The user also may tailor decay rate characteristics
on an individual basis. An integrated decay rate constant calculator is provided for landfills that
may be operating a gas recovery system to allow more accurate assessments of decay attributes.
Outputs may be reviewed in either tabular or graphical forms. A help system is also provided
with information on the model operation as well as details on assumptions and defaults used by
the system. For additional information contact the EPA's Air Pollution Prevention and Control
Division at (919) 541-2709. The model can be downloaded from the World Wide Web through
EPA's TTN Web site at http://www.epa.gov/ttn/catc/products.htmffisoftware.
TANKS
TANKS is a Windows-based computer software program that computes estimates of VOC
emissions from fixed- and floating-roof storage tanks based on the emission estimation
procedures from Chapter 7 of AP-42, plus recent updates from the American Petroleum Institute.
The TANKS program employs a chemical database of over 100 organic liquids and meteorology
data from over 250 cities in the United States. The user may add new chemicals and cities to
their version of the database. The tank types addressed in the program include vertical and
horizontal fixed roof tanks, and internal and external floating roof tanks. The tank contents can
consist of single-component liquid or a multicomponent mixture. TANKS is available through
the EPA's TTN Web site at http://www.epa.gov/ttn/chief/tanks.html.
WATERS
WATERS is an analytical model for estimating compound-specific air emissions from
wastewater collection & treatment systems including aerated basins, and other units. WATERS
contains useful features such as the ability to link treatment units to form a treatment system, the
ability for recycle among units, and the ability to generate and save site-specific compound
properties. WATERS uses some of the same models found in CHEMDAT8, but has a database
with compound-specific data for over 950 chemicals. WATERS is available through the EPA's
TTN Web site at http://www.epa.gov/ttn/chief/software.htmffiwater8.
G-l
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CHEMDAT8
CHEMDAT8 is a Lotus 1-2-3 spreadsheet that includes analytical models for estimating
emissions from treatment, storage and disposal facility (TSDF) processes. The original models
include disposal impoundments, closed landfills, land treatment facilities, and aeration and
nonaeration impoundment processes.
The models in CHEMDAT8 can be applied to other types of TSDF processes besides those
contained in the original design. The nonaerated impoundment model in CFIEMDAT8 can
estimate emissions from storage surface impoundments and open-top wastewater treatment
tanks. The CFIEMDAT8 aerated impoundment model may be used for predicting emissions
from surface treatment impoundments and aerated wastewater treatment tanks. The land
treatment model in CFIEMDAT8 can estimate emissions from land treatment soil, open landfills,
and wastepiles. Emissions from an oil film surface in a land treatment facility or an oil film on
surface impoundments can be predicted via the oil film model in CFIEMDAT8. When a
CHEMDAT8 model is not available to predict emissions, the equations shown in the reports that
provide the background to the model can be used to perform hand calculations of emissions.
This eighth version of the CFIEMDAT spreadsheet contains several major operational
modifications. In CHEMDAT8, the user can select a subset of target compounds for
investigation. The user can also specify which TSDF processes are to be considered during a
session. These two selections improve the efficiency of CFIEMDAT8 relative to some of the
earlier versions by minimizing storage requirements as well as actual loading and execution time.
Default input parameters in the CHEMDAT8 diskette demonstrate example calculations.
However, the input parameters can be changed to reflect different TSDF characteristics and then
recalculate emissions under these modified conditions. The list of 60 compounds currently in
CHEMDAT8 can be augmented by an additional 700 chemicals. Procedures for introducing data
for additional compounds into CHEMDAT8 are described in the supporting documentation
report. CHEMDAT8 is available through the EPA's TTN Web site at
http://www. epa.gov/ttn/chief/software. html#water8.
MECH
MECH is a computer program which estimates particulate emissions from paved roads, unpaved
roads, materials handling, agricultural tilling and construction & demolition operations. This
program automates the calculation routines contained in the EPA document titled Control of
Open Fugitive Dust Sources (EPA, 1988). MECH is available through the EPA's TTN Web site
at http://www. epa.gov/ttn/chief/software.html#fugitive
G-2
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PM Calc
PM Calc is a computer software developed by EPA to estimate PM2.5 emissions. PM Calc is
applicable to point sources and requires the user to input uncontrolled emissions (either total
particulate or PM10) for each source, the source category classification (SCC) and the type of
control device, if any. The program will then calculate controlled emissions for PM2.5 and
PM10 for each point source. PM Calc is available through the EPA's TTN Web site at
http://www. epa.gov/ttn/chief/software. html#fugitive
Compilation of Air Pollutant Emission Factors (AP-42)
The primary reference for criteria pollutant emission factors for industrial sources is AP-42
(EPA, 1998). EPA is continuously updating AP-42 to include available emission factors for the
most common emission source categories.
The extent of completeness and detail of the emission information in AP-42 is determined by the
information available from published references. Emissions from some processes are better
documented than others. For example, several emission factors may be listed for the production
of one substance: one factor for each of a number of steps in the production process such as
neutralization, drying, distillation, and other operations. However, because of less extensive
information, only one emission factor may be given for production facility releases for another
substance, though emissions are probably produced during several intermediate steps. There may
be more than one emission factor for the production of a certain substance because differing
production processes may exist, or because different control devices may be used. Therefore, it is
necessary to look at more than just the emission factor for a particular application and to observe
details in the text and in table footnotes of AP-42.
Each AP-42 emission factor is given a rating from A through E, with A being the best. A factor's
rating is a general indication of the reliability, or robustness, of that factor. This rating is
assigned based on the estimated reliability of the tests used to develop the factor and on both the
amount and the representative characteristics of those data. Because ratings are subjective and
only indirectly consider the inherent scatter among the data used to calculate factors, the ratings
should be seen only as approximations. A rating should be considered an indicator of the
accuracy and precision of a given factor being used to estimate emissions from a large number of
sources. This indicator is largely a reflection of the professional judgment of AP-42 authors and
reviewers concerning the reliability of any estimates derived with these factors.
The fact that an emission factor for a pollutant or process is not available from EPA does not
imply that the Agency believes the source does not emit that pollutant or that the source should
not be inventoried, but it is only that EPA does not have enough data to provide any advice.
AP-42 must be considered work-in-progress. Up-to-date sections of AP-42 can be downloaded
off the World Wide Web through OAQPS' TTN Web site at
http://www.epa.gov/ttn/chief/ap42etc.html. AP-42 is also available through Fax CHIEF
G-3
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automated fax document delivery service, through the Air CHIEF CD-ROM, and in hard copy
from the Government Printing Office (202) 512-1800.
Factor Information Retrieval (FIRE) Data System
FIRE is a database management system containing:
• EPA's recommended emission estimation factors for criteria pollutants and HAPs;
• Information about industries, their emitting processes, and chemicals emitted;
All EPA point and area SCCs through March 1999;
• Easy access to emission factors obtained from AP-42, L&E series documents,
factors derived from state-reported test data, and factors taken from literature
searches;
• Each emission factor entry includes comments about its development, in terms of
the calculation methods and/or source conditions, as well as the references where
the data were obtained. The emission factor entry also includes a data quality
rating;
• Capability for users to browse through records in the database or to select specific
emission factors by source category name or source classification code (SCC), by
pollutant name or CAS number, or by control device type or code.
FIRE Version 6.2 (released April 1999) is a user-friendly, menu-driven Windows program that
can run under Windows Version 3.1, 95 or Windows NT. FIRE can be downloaded off the
World Wide Web through OAQPS' TTN Web site at http://www.epa.gov/ttn/chief/fire.html.
FIRE is also available on the Air CHIEF, a compact disc read-only memory (CD- ROM) and can
be obtained by calling the Info CHIEF Help Desk.
Air Clearinghouse for Inventories and Emission Factors (Air CHIEF) CD-ROM
Air CHIEF CD-ROM format, gives access to air emission data specific to estimating the types
and quantities of pollutants that may be emitted from a wide variety of sources. Updated
annually, Air CHIEF offers thousands of pages contained in some of EPA's most widely used
documents. This most recent version of Air CHIEF contains many enhancements, such as
linking between related documents, Web links directly to the CHIEF Web site for easy access to
the most recent updates, and enhanced full-CD searching. The Adobe Acrobat® software
included on the CD allows for easy browsing of all information or locating specific information
by conducting keyword searches by pollutant, source category, SCC, or SIC code. Some of the
databases included on Air CHIEF version 6.0 are: (1) AP-42; (2) L&E documents; (3) EIIP
G-4
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documents; (4) AP-42 background files; and (5) FIRE version 6.1. Also included on Air CHIEF
are the installable copies of these MS-DOS software programs: BEIS, Water 8, Chemdat 8, and
PMCALC.
Air CHIEF version 6.0 is available for distribution by GPO for $15.00 (Stock Number:
055-000-00609-1) and can be ordered by calling GPO at (202) 512-1800, or by ordering online
through OAQPS' TTN Web site at http://www.epa.gov/ttn/chief/airchief.htmffiorder.
Version 6.0 will be released in November 1998.
G-5
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G-6
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APPENDIX H
LIST OF L&E DOCUMENTS
(http://www.epa.gov/ttn/chief/ap42etc.htmMLE)
(Current as of August 1999)
-------
List
Substance
Acrylonitrile
Arsenic
Benzene
Butadiene
Cadmium
Carbon Tetrachloride
Chlorobenzene (update)
Chloroform
Chromium (supplement)
Chromium
Cyanide Compounds
Dioxins and Furans
Epichlorohydrin
Ethylene Bichloride
Ethylene Oxide
Formaldehyde
Lead
Manganese
Mercury
Methyl Chloroform
Methyl Ethyl Ketone
Methylene Chloride
Nickel
Organic Liquid Storage Tanks
Perchloroethylene and Trichloroethylene
Phosgene
Polychlorinated Biphenyls (PCBs)
Polycyclic Organic Matter (POM)
Styrene
Toluene
Vinylidene Chloride
Xylenes
ofL&E Documents
EPA Publication
Number
EPA-450/4-84-007a
EPA-454/R-98-013
EPA-454/R-98-011
EPA-454/R-96-008
EPA-454/R-93-040
EPA-450/4-84-007b
EPA-454/R-93-044
EPA-450/4-84-007c
EPA-450/2-89-002
EPA-450/4-84-007g
EPA-454/R-93-041
EPA-454/R-97-003
EPA-450/4-84-007J
EPA-450/4-84-007d
EPA-450/4-84-0071
EPA-450/4-91-012
EPA-454/R-98-006
EPA-450/4-84-007h
EPA-453/R-97-012
EPA-454/R-93-045
EPA-454/R-93-046
EPA-454/R-93-006
EPA-450/4-84-007f
EPA-450/4-88-004
EPA-450/2-89-013
EPA-450/4-84-0071
EPA-450/4-84-007n
EPA-454/R-98-014
EPA-454/R-93-011
EPA-454/R-93-047
EPA-450/4-84-007k
EPA-454/R-93-048
Available On
Line?
NO
YES
YES
YES
YES
NO
YES
NO
YES
YES
YES
YES
YES
NO
YES
YES
YES
NO
YES
YES
YES
YES
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
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H-2
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APPENDIX I
OPTIONS FOR DATA REPORTING
-------
Options for Data Reporting
You can submit your data to EPA using one of several data transfer options. The appropriate
data transfer method is identified during the planning stage of the inventory process, based on the
end use of the inventory and availability of resources.
At this time the NET Input Format and the AIRS/AFS are equally viable options for submitting
the point source data. The NET Input Format is the preferred option for submitting area data.
You should keep in mind that information technology is a rapidly changing field, and electronic
reporting of inventory data is an evolving issue. Refer to the EPA Data Submission page at
http:/www.epa.gov/ttn/chief/ei/eisubmit.html for updates on emissions reporting.
Four options are available for data reporting:
• Aerometric Information Retrieval System/Aerometric Information Retrieval
Facility Subsystem (AIRS/AFS) - AIRS is a computer-based system for the
storage and retrieval of ambient air quality monitoring data and emissions and
compliance data for individual facilities. AFS contains emissions, compliance,
and permit data for point sources regulated or tracked by federal, state, and local
air pollution agencies.
This is the option that has been used for transferring SIP and annual emission
inventory data to EPA. This option may be used to transfer only point source
data. State and local agencies can upload industrial facility data directly to
AIRS/AFS. EPA will extract the point source data submitted to AIRS/AFS and
translate it into a format compatible with storage in the EPA National Emissions
Trends (NET) database. You can find more information on the use of this option
on the World Wide Web at http:/www. epa.gov/airsdata.
For states that submit point source data via AIRS/AFS, it is necessary to use one
of the other data transfer options to submit area, mobile, and biogenic data. Note,
However, that the emissions component of AIRS/AFS will be phased out by the
end of September, 2000, and the data transferred to the NET format. You should
consult the AIRS/AFS Web site at http://www.epa.gov/ttn/airs/afs/index.html for
the latest memos and information on the plans to migrate the emissions
component of AIRS/AFS to the NET database.
• NET Input Format - The NET is an Oracle database that contains emission
estimates of carbon monoxide, nitrogen oxides, sulfur dioxide, volatile organic
compounds, particulate matter, lead, hazardous air pollutants, and ammonia from
point, area, nonroad mobile, onroad mobile, and biogenic sources. The Emission
Factor and Inventory Group is redesigning its NET database in Oracle using the
EIIP Phase I Data Model as one of the primary design criteria.
1-1
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The NET Input Format creates relational, normalized data sets which conform to
the relational standards and structure of the NET Oracle database. The flexibility
of the format design enables it to be mapped to a wide variety of alternative
database structures (e.g., state/local systems, EPA systems). By avoiding
duplication of data, the data set(s) created in this format are optimized in terms of
the file space and the time it takes for electronic transfer to EPA.
EFIG will process and load the NET input files into its NET database system
You should note that point source data submitted to the NET will not be
transferred to AFS. If you are interested in obtaining the EPA's new NET Oracle
database structure, contact the Technical Support Center at 800-334-2405 or
919-541-7862 for additional details.
EIIP EDI X12 - The EIIP Data management Committee has developed a data
transfer format using existing electronic data interchange (EDI) X12 standards.
The EDI data exchange standard is a nonproprietary standard created and
maintained by the American National Standards Institute (ANSI) X12 committee.
This format is described in EIIP Volume VII, Data Management. The EDI data
transfer procedure may be available to state/local agencies through EPA
assistance. If your agency would like to use this option, contact the Technical
Support Center at 800-334-2405 or 919-541-7862 to obtain advice on how to
proceed.
Agencies choosing to use this option will need to develop an application interface
and procure an EDI translator, or use a translator provided by the EIIP/EDI data
transfer demonstration. The standardized format generated by this approach will
be loaded by EPA into the NET database system. The EIIP/EDI procedure allows
an agency to submit their point, area, mobile, and biogenic information in a single
file.
While the EIIP successfully tested the use of EDI through its prototype
demonstration, the EPA is determining how to best establish and support EDI data
transfer procedures across the Agency. To learn more about the EDI data transfer
technique and the results of the EIIP prototype demonstration, see the EIIP Data
Management Committee, Procedures Documents page at
www. epa.gov/ttn/chief/eiip/.
Direct Source Reporting - Point sources may already be reporting electronic
emissions inventory data to EPA as part of Title IV or regional NOX trading
programs. For example, electricity-generating units subject to Title IV Acid Rain
monitoring and reporting provisions must report continuous emission monitoring
(CEM) data to EPA in a specified electronic data reporting (EDR) format.
Submission of this data will not fulfill reporting requirements for ozone, PM, or
1-2
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regional haze SIP inventory submittal, but EPA recognizes this as a viable data
option where reporting requirements overlap.
To avoid duplication of efforts, EPA envisions that the emissions data submitted directly to EPA
from the source will be:
• Transferred to EPA's NET database; or
• Made available to the states for incorporation into their emissions inventories,
which will then entered into the NET database.
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1-4
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APPENDIX J
1997 CRITERIA POLLUTANTS EMISSIONS
BY SOURCE CATEGORY
-------
Contents
Table Page
1 1997 National Carbon Monoxide (CO) Emissions Estimates from Stationary
Sources (1,000 Short Tons) J-l
2 1997 National Lead (Pb) Emissions Estimates from Stationary Sources
(1,000 Short Tons) J-2
3 1997 National Nitrogen Oxide (NOX) Emissions Estimates from Stationary
Sources (1,000 Short Tons) J-3
4 1997 National PM2 5 Emissions Estimates from Stationary Sources
(1,000 Short Tons) ' J-4
5 1997 National PM10 Emissions Estimates from Stationary Sources
(1,000 Short Tons) J-5
6 1997 National Sulfur Oxides (SOX) Emissions Estimates from Stationary
Sources (1,000 Short Tons) J-6
7 1997 National Volatile Organic Compounds (VOC) Emissions Estimates from
Stationary Sources (1,000 Short Tons) J-7
J-ii
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J-iii
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Table 1. 1997 National Carbon Monoxide (CO) Emissions Estimates
from Stationary Sources (1,000 Short Tons)
Source Category
Fuel Combustion
Electric Utilities
Coal
Other Fuels
Industrial
Gas
Other Fuels
Other Sources
Residential
Commercial/Institutional
Industrial Processes
Chemical and Allied Processing
Carbon Black
Other Chemical Processing
Metals Processing
Ferrous Metals Processing
Other Metal Processing
Petroleum and Related Industries
Petroleum Refineries
Other Petroleum Industries
Other Industrial Processes
Wood, Pulp and Paper
Other Processes
Solvent Utilization
Storage and Transport
Waste Disposal and Recycling
Open Burning
Other Disposal
Miscellaneous Sources
Slash/Prescribed Burning
Forest Wildfires
Other
Total Emissions
1997
Emissions
4,817
406
254
152
1,110
362
748
3,310
3,042
268
6,052
7,257
889
398
2, 465
1,999
466
364
323
41
663
515
148
6
26
1,242
772
470
9,568
5,033
3,863
672
20,437
Percent
Contribution
24%
8%
63%
37%
23%
33%
67%
69%
92%
8%
30%
27%
69%
31%
41%
81%
19%
6%
89%
11%
77%
78%
22%
0.7%
0.4%
21%
62%
38%
47%
53%
40%
7%
100%
Source: National Air Pollutant Emission Trends Update: 1970-1997 (December 1998), EPA-454/E-98-007.
J-l
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Table 2. 1997 National Lead (Pb) Emissions Estimates
from Stationary Sources (1,000 Short Tons)
Source Category
Fuel Combustion
Electric Utilities
Coal
Other Fuels
Industrial
Other Sources
Industrial Processes
Chemical and Allied Processing
Lead Oxide and Pigment Manufacturing
Metals Processing
Nonferrous Metals Processing
Other Metals Processing
Other Industrial Processes
Waste Disposal and Recycling
Total Emissions
1997
Emissions
496
64
53
11
17
415
2,897
759
159
2,038
1,320
718
54
646
3,393
Percent
Contribution
15%
73%
83%
17%
3%
84%
85%
5%
100%
70%
65%
35%
2%
22%
100%
Source: National Air Pollutant Emission Trends Update: 1970-1997 (December 1998), EPA-454/E-98-007.
J-2
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Table 3. 1997 National Nitrogen Oxides (NOX) Emissions Estimates
from Stationary Sources (1,000 Short Tons)
Source Category
Fuel Combustion
Electric Utilities
Coal
Other Fuels
Industrial
Gas
Other Fuels
Other Sources
Residential
Commercial/Institutional
Industrial Processes
Chemical and Allied Processing
Agricultural Chemical Manufacturing
Other Chemical Manufacturing
Metals Processing
Ferrous Metals Processing
Other Metals Processing
Petroleum and Related Industries
Oil and Gas Production
Other Petroleum Industries
Other Industrial Processes
Mineral Products
Other Processes
Solvent Utilization
Storage and Transport
Waste Disposal and Recycling
Incineration
Open Burning
Other Disposal and Recycling
Miscellaneous Sources
Other Combustion
Fugitive Dust
Total Emissions
1997
Emissions
10,724
6,178
5,599
579
3,270
1,385
1,885
1,276
859
417
917
167
78
89
102
86
16
115
60
55
421
303
118
3
6
103
56
46
2
346
344
1
11,987
Percent
Contribution
89%
58%
91%
9%
30%
42%
58%
72%
67%
33%
8%
75%
47%
53%
77%
84%
16%
73%
52%
48%
46%
72%
28%
0.3%
7%
77%
54%
45%
1%
3%
99%
0.3%
100%
Source: National Air Pollutant Emission Trends Update: 1970-1997 (December 1998), EPA-454/E-98-007.
J-3
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Table 4. 1997 National PM2 5 Emissions Estimates from
Stationary Sources (1,000 Short Tons)
Source Category
Fuel Combustion
Electric Utilities
Coal
Other Fuels
Industrial
Internal Combustion
Other Industrial
Other Sources
Residential Fuels
Other (Including Commercial/Institutional)
Industrial Processes
Chemical and Allied Products
Organic Chemical Manufacturing
Other Chemical Manufacturing
Metals Processing
Ferrous Metals Processing
Other Metals Processing
Petroleum and Related Industries
Other Industrial Processes
Mineral Products
Other Processes
Solvent Utilization
Storage and Transport
Bulk Material Storage
Other Storage and Transport
Waste Disposal and Recycling
Open Burning
Other Disposal and Recycling
Miscellaneous Sources
Agriculture and Forestry
Fugitive Dust
Other Sources
Natural Sources
Total Emissions
1997
Emissions
847
158
134
24
273
51
162
476
384
92
111
44
12
32
139
96
43
23
267
138
129
6
44
43
1
254
200
54
5,272
925
3,461
886
797
7.693
Percent
Contribution
11%
79%
85%
15%
25%
24%
76%
56%
81%
19%
10%
6%
27%
73%
75%
69%
31%
3%
34%
52%
48%
0.5%
6%
98%
2%
33%
79%
21%
69%
75%
66%
17%
10%
100%
Source: National Air Pollutant Emission Trends Update: 1970-1997 (December 1998), EPA-454/E-98-007.
J-4
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Table 5. 1997 National PM10 Emissions Estimates from
Stationary Sources (1,000 Short Tons)
Source Category
Fuel Combustion
Electric Utilities
Coal
Other Fuels
Industrial
Coal
Internal Combustion
Other Industrial
Other Sources
Residential Fuels
Other (Including Commercial/Institutional)
Industrial Processes
Chemical and Allied Products
Metals Processing
Ferrous Metals Processing
Other Metals Processing
Petroleum and Related Industries
Other Industrial Processes
Mineral Products
Other Processes
Solvent Utilization
Storage and Transport
Bulk Material Storage
Other Storage and Transport
Waste Disposal and Recycling
Open Burning
Other Disposal and Recycling
Miscellaneous Sources
Agriculture and Forestry
Fugitive Dust
Other Sources
Natural Sources
Total Emissions
1997
Emissions
1,101
290
265
25
314
72
68
174
¥97
388
109
1,277
70
220
155
65
41
530
326
204
6
114
112
2
296
220
76
25,153
4,707
19,429
1,017
5,316
32,847
Percent
Contribution
3%
26%
91%
9%
29%
23%
22%
55%
¥5%
78%
22%
4%
5%
17%
70%
30%
3%
42%
62%
38%
0.5%
9%
98%
2%
23%
74%
26%
77%
19%
77%
4%
16%
100%
Source: National Air Pollutant Emission Trends Update: 1970-1997 (December 1998), EPA-454/E-98-007.
J-5
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Table 6. 1997 National Sulfur Oxides (SOX) Emissions Estimates
from Stationary Sources (1,000 Short Tons)
Source Category
Fuel Combustion
Electric Utilities
Coal
Other Fuels
Industrial
Gas
Other Fuel
Other Sources
Commercial/Institutional
Other (Including Residential)
Industrial Processes
Chemical and Allied Processing
Inorganic Chemical Manufacturing
Other Chemical Manufacturing
Metals Processing
Nonferrous Metals Processing
Other Metals Processing
Petroleum and Related Industries
Petroleum Refineries
Other Petroleum
Other Industrial Processes
Mineral Products
Other Industrial Processes
Solvent Utilization
Storage and Transport
Waste Disposal and Recycling
Miscellaneous Sources
Total Emissions
1997
Emissions
17,260
13,082
12,531
551
3,365
1,769
1,596
813
620
193
1,718
301
208
93
552
378
174
355
283
102
427
297
130
1
2
50
13
18,991
Percent
Contribution
91%
76%
96%
4%
79%
53%
47%
5%
76%
24%
9%
75%
69%
31%
32%
68%
32%
22%
74%
26%
25%
70%
30%
0.7%
0.7%
3%
0.1%
100%
Source: National Air Pollutant Emission Trends Update: 1970-1997 (December 1998), EPA-454/E-98-007.
J-6
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Table 7. 1997 National Volatile Organic Compound (VOC) Emissions
Estimates from Stationary Sources (1,000 Short Tons)
Source Category
Fuel Combustion
Electric Utilities
Industrial
Gas
Other Fuels
Other Sources
Residential Wood (Fireplaces)
Other (including commercial/institutional fuel and other
residential)
Industrial Processes
Chemical and Allied Products
Polymer and Resins Manufacturing
Other Chemical Processing
Metals Processing
Petroleum and Related Industries
Oil and Gas Production
Petroleum Refineries and Related Processes
Other Petroleum Industries
Other Industrial Processes
Agriculture, Food, and Kindred Products
Wood, Pulp and Paper
Other Industrial Processes
Solvent Utilization
Degreasing
Graphic Arts
Industrial Adhesives
Architectural Coating
Pesticide Application
Non-industrial Adhesives
Consumer Solvents
Other Solvent Utilization
Storage and Transport
Bulk Terminals and Plants
Service Stations: Stage I
1997
Emissions
861
51
217
77
140
593
527
66
9,836
458
142
316
73
538
282
252
4
458
141
129
188
6,483
692
412
475
558
382
406
1,219
2,339
7,377
255
359
Percent
Contribution
7%
6%
25%
35%
65%
69%
89%
11%
85%
5%
31%
69%
1%
5%
52%
47%
1%
5%
31%
28%
41%
66%
11%
6%
7%
9%
6%
6%
19%
36%
14%
19%
26%
J-7
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Table 7. 1997 National Volatile Organic Compound (VOC) Emissions
Estimates from Stationary Sources (1,000 Short Tons) (Continued)
Source Category
Service Stations: Stage II
Other Storage and Transport
Waste Disposal and Recycling
Miscellaneous Sources
Slash/Prescribed Burning
Forest Wildfires
Other
Total Emissions
1997
Emissions
427
336
449
858
262
421
175
11,555
Percent
Contribution
31%
24%
5%
7%
37%
49%
20%
100%
Source: National Air Pollutant Emission Trends Update: 1970-1997 (December 1998), EPA-454/E-98-007.
J-8
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APPENDIX K
LIST OF POTENTIAL POINT SOURCE
CATEGORIES BY POLLUTANT
-------
List of Potential Point Source
Categories by Pollutant
Category
S07
PM
voc
NOT
CO
Fuel Combustion - Electric Utility
Coal
Gas
Internal Combustion
Oil
Other
H
L
L
M
/
H
/
M
L
/
L
L
L
L
/
H
M
M
L
/
L
L
L
L
/
Fuel Combustion - Industrial
Coal
Gas
Internal Combustion
Oil
Other
H
H
L
M
L
M
M
M
M
H
L
M
M
L
L
M
M
H
M
L
L
L
L
L
L
Fuel Combustion - Other
Commercial/Institutional Coal
Commercial/Institutional Gas
Commercial/Institutional Oil
Residential Wood
Residential Other
Miscellaneous Fuel Combustion except Residential
M
L
L
/
/
L
L
L
L
/
/
L
/
L
L
/
/
L
L
L
L
/
/
L
L
L
L
/
/
L
Chemical and Allied Products Manufacturing
Agricultural Chemicals
Inorganic Chemicals
Organic Chemicals
Paints, Varnishes, Lacquers, Enamels
Pharmaceuticals
Polymers and Resins
Other Chemicals
L
M
L
/
/
/
L
L
L
M
/
/
L
M
L
L
M
L
L
M
M
L
L
L
/
/
L
L
L
L
L
/
/
L
M
Metal Processing
Ferrous Metals
Nonferrous Metals
Metals Processing NEC
M
M
L
H
M
M
L
L
L
L
L
L
M
L
L
Petroleum and Related Industries
Asphalt Manufacturing
Oil and Gas Production
L
L
L
/
L
M
L
L
L
L
K-l
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List of Potential Point Source
Categories by Pollutant (Continued)
Category
Petroleum Refineries and Related Industries
SO,
M
PM
M
voc
M
NOV
L
CO
L
Other Industrial Processes
Agricultural, Food, and Kindred Products
Construction
Electronic Equipment
Machinery Products
Mineral Products
Rubber and Miscellaneous Plastic Products
Textiles, Leather, and Apparel Products
Transportation Equipment
Wood, Pulp and Paper, and Publishing Products
Miscellaneous Industrial Processes
L
/
/
M
/
/
/
M
L
M
/
/
L
H
L
/
/
H
/
M
L
L
L
M
L
L
M
L
L
/
L
M
/
/
/
L
L
L
L
/
L
/
/
/
L
L
Solvent Utilization
Degreasing
Dry Cleaning
Graphic Arts
Other Industrial
Surface Coating
/
/
/
L
/
/
/
L
L
M
L
H
/
/
/
L
/
/
/
L
Storage and Transport
Bulk Materials Storage
Bulk Materials Transport
Bulk Terminals and Plants
Inorganic Chemical Storage
Inorganic Chemical Transport
Organic Chemical Storage
Organic Chemical Transport
Petroleum and Petroleum Product Storage
Petroleum and Petroleum Product Transport
Service Stations: Stage I
Service Stations: Stage II
/
/
/
/
/
/
/
/
/
M
/
/
/
/
/
/
/
/
/
/
M
/
L
L
M
M
L
L
/
/
/
/
L
/
/
/
/
L
L
/
L
/
/
/
/
Waste Disposal and Recycling
Incineration
Industrial Waste Water
Landfills
L
/
/
M
/
/
L
L
L
L
/
/
L
/
L
K-2
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List of Potential Point Source
Categories by Pollutant (Continued)
Category
POTWs
TSDFs
Other
SO,
/
/
PM
/
/
/
voc
L
L
L
NOV
/
/
/
CO
/
/
/
Miscellaneous
Cooling Towers
Health Services
L
L
/
/
/
Source: EPA. 1999. Emissions Inventory Guidance for Implementation of Ozone and Paniculate Matter National
Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations. U.S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.
Notes: The H (high), M (medium), and L (low) designations indicate the level of significance of a source category's
emissions to the overall emissions of that pollutant.
A "/" indicates that emissions of that pollutant may occur from that source category, but they are not
considered significant.
A blank cell indicates that no emissions of that pollutant are emitted from that source category based on the
data in EPA's NET inventory.
K-3
-------
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K-4
-------
APPENDIX L
LIST OF POTENTIAL AREA SOURCE
CATEGORIES BY POLLUTANT
-------
List of Potential Area Source Categories By Pollutant
Category
SO,
PM
voc
NOT
CO
Fuel Combustion - Electric Utility
Internal Combustion
/
L
L
Fuel Combustion - Industrial
Coal
Gas
Internal Combustion
Oil
Other
H
L
/
H
L
L
L
/
L
L
L
L
L
L
L
L
M
L
L
L
L
L
L
L
L
Fuel Combustion - Other
Commercial/Institutional Coal
Commercial/Institutional Gas
Commercial/Institutional Oil
Residential Wood
Residential Other
Miscellaneous Fuel Combustion except Residential
L
L
M
L
M
L
L
L
L
H
M
H
/
L
L
H
L
L
L
M
L
L
H
L
L
L
L
M
L
L
Chemical and Allied Products Manufacturing
Inorganic Chemicals
Organic Chemicals
Pharmaceuticals
Polymers and Resins
M
/
L
L
/
Metal Processing
Ferrous Metals
Nonferrous Metals
Metals Processing NEC
/
/
/
/
/
/
/
/
Petroleum and Related Industries
Asphalt Manufacturing
Oil and Gas Production
Petroleum Refineries and Related Industries
L
L
/
M
M
/
L
/
L
Other Industrial Processes
Agricultural, Food, and Kindred Products
Machinery Products
Mineral Products
Rubber and Miscellaneous Plastic Products
/
L
/
/
M
/
/
L
/
/
L
/
/
L-l
-------
List of Potential Area Source Categories By Pollutant (Continued)
Category
Wood, Pulp and Paper, and Publishing Products
Miscellaneous Industrial Processes
SO,
L
PM
L
M
voc
/
L
NOV
/
L
CO
/
/
Solvent Utilization
Degreasing
Dry Cleaning
Graphic Arts
Nonindustrial
Other Industrial
Surface Coating
Solvent Utilization NEC
H
M
M
H
L
H
/
/
/
/
Storage and Transport
Bulk Materials Storage
Bulk Terminals and Plants
Organic Chemical Storage
Petroleum and Petroleum Product Storage
Petroleum and Petroleum Product Transport
Service Stations: Breathing and Emptying
Service Stations: Stage I
Service Stations: Stage II
M
L
L
L
L
H
H
/
Waste Disposal and Recycling
Incineration
Industrial Waste Water
Landfills
Open Burning
POTWs
TSDFs
Other
L
L
M
H
L
L
L
M
L
L
L
L
/
L
/
L
/
L
/
Miscellaneous
Agriculture and Forestry
Catastrophic/Accidental Releases
Health Services
Other Combustion (Structure Fires, Forest Fires, Slash
Burning, Prescribed Burning, Managed Burning)
L
L
H
M
L
/
H
M
H
L-2
-------
List of Potential Area Source Categories By Pollutant (Continued)
Category
SO,
PM
voc
NO,
CO
Natural Sources
Geogenic, Wind Erosion
M
Miscellaneous
Agricultural Crops (Tillage)
Construction
Paved Roads
Unpaved Roads
Other Fugitive Dust (e.g., Mining and Quarrying)
M
M
M
H
M
Source: EPA. 1999. Emissions Inventory Guidance for Implementation of Ozone and Paniculate Matter National
Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations. U.S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.
Notes: The H (high), M (medium), and L (low) designations indicate the level of significance of a source category's
emissions to the overall emissions of that pollutant.
A "/" indicates that emissions of that pollutant may occur from that source category, but they are not
considered significant.
A blank cell indicates that no emissions of that pollutant are emitted from that source category based on the
data in EPA's NET inventory.
L-3
-------
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L-4
-------
APPENDIX M
GUIDANCE ON HOW TO CONDUCT SCREENING STUDIES
-------
Contents
Section Page
ELEMENTS M-l
Cover Letter M-l
Questionnaire Instructions M-2
Questionnaire Design M-2
OTHER CONSIDERATIONS M-7
The Right Questions M-7
The Return Rate M-8
Confidentiality M-9
Applicability and Clarity of Questions M-10
Complexity and Questionnaire Format M-10
Clarity of Instructions M-l 1
Final Considerations M-12
FOLLOW-UP PROCEDURES M-15
Quality Control of Data M-15
On-Site Inspections M-15
Recontacting Sources M-16
Revising the Questionnaire M-16
Sample Survey Forms for the Dry Cleaning Industry M-19
M-ii
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M-iii
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ELEMENTS
An emission inventory questionnaire mail-out has three basic elements: the cover letter, the
questionnaire instructions, and the questionnaire itself. The questionnaire format and content
depends on the detail of the inventory and the ultimate use of the data. All of these components,
when considered together, make up the questionnaire package.
Cover Letter
The cover letter is a key to the emission inventory, because it introduces the purpose of the
questionnaire and is the initial contact with the recipient. If the cover letter does not command
attention, the attached questionnaire may be discarded or filed away and not considered a top
priority. This could make the number of companies requiring recontact by agency personnel
increase dramatically.
The cover letter should include the following:
• Applicable regulations, if any, that require the recipient to respond;
• Confidentiality provisions, if applicable;
• The purpose of the questionnaire;
• A respectful request for cooperation in filling out the questionnaire;
• Due date for the return of completed questionnaires;
• A state or local agency contact name and telephone number to answer questions;
and
• Rationale for asking for what may appear to the source to be redundant
information.
The cover letter should be as short and direct as possible. The most successful return rates for
questionnaires have been the ones having the strongest legal statements. Therefore, states/local
agencies requiring source registration to obtain construction or operating permits may obtain
better source cooperation.
A strong statement about existing and applicable regulations which require a recipient to respond
to the questionnaire is the agency's most powerful tool for maximizing the return rate. The
statement should be placed prominently in the beginning or at the top of the cover letter. It
should cite any applicable regulations or proposed regulations and specify penalties for
noncompliance.
M-l
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Another important item to include in a cover letter to ensure a high return rate is the due date.
The final due date should be included in the cover letter to that it will not be overlooked by those
who do not read instructions. The due date may be specified either as a stated date or as a period
of time after the recipient receives the questionnaire. The first approach is more specific, and
gives the recipient a definite deadline. With the latter approach however, the questionnaire
mailing can be staggered without having to reprint the due dates listed on the cover letter. The
agency should record each due date so it will be clear when follow-up letters or phone calls may
need to begin for tardy respondents.
Questionnaire Instructions
General information that affects the whole questionnaire may be included first on the instruction
page. For example, if the questionnaire is "open-ended" (i.e., asks the recipient to list every toxic
compound from every emission source) , it should be clear that the respondent should use
chemical compound names or preferably CAS numbers and not just industrial trade names.
Also, it may be helpful to point out that not all questions, sections, or pages may apply to every
industry, as in a source category specific directed questionnaire. If the questions are designed for
direct coding to computer input, the general instructions should explain how to enter numbers
properly. In addition to explaining how to complete the questionnaire, the general instructions
should indicate the specific year, or other appropriate period of time, for which all data are
required.
Some agencies have utilized production/use questionnaires which basically just ask sources to
identify whether each substance is purchased, used, or produced, followed by a more detailed
questionnaire targeted to specific industries. Some agencies include minimum usage or
emissions levels specified on an attached list as part of the instructions.
Questionnaire Design
There are several ways to design a questionnaire. Of utmost importance when designing a
questionnaire is that the format suits the needs of the agency and attains correct responses and
maintains a good agency-industry working relationship.
Several approaches can be taken in designing the questionnaire which, in turn, will effect the
format of the questionnaire. The approaches that can be used include: open vs. closed-ended,
emission-based vs. chemical use, permit related, and general vs. industry-specific. In order for an
agency to decide which approach to use, it needs to be familiar with some of the impacts of each
approach.
Each agency should tailor their inventory package according to their agency's individual needs.
Many times, the examples are a combination of approaches. For instance, in one case a general
design questionnaire was sent to various manufacturers and process industries, and later, industry
specific questionnaires were sent to a small subset of the original recipients. In still another case
M-2
-------
a screening study was first done to narrow down the number of sources to be inventoried and
indicated the design needs of the final questionnaire to be sent out. Later, a second questionnaire
was sent.
The following sections explain the advantages and disadvantages of various type questionnaire
designs. These are not necessarily mutually exclusive.
Open-Ended Approach
The open-ended approach does not target specific source types or a limited group of compounds.
The open-ended approach asks the respondent to list any compound that they emit. It does not
provide a checklist of compounds. Therefore, with an open-minded approach a much larger
number of contacts will be necessary. This approach has several similarities to a screening study:
• Less time and effort in questionnaire design;
• Responses may be less detailed;
• More responses may be inaccurate or trade names (not chemical compound names)
may be listed; and
• Some sources may report no air toxic emissions.
Closed-Ended Approach
The closed-ended approach is a more direct approach, which usually provides a limited list of
compounds with the questionnaire. Some agencies' list lists of toxic compounds are becoming
rather extensive and use of CAS numbers is widespread. This approach requires more design
time up from (e.g. screening studies, modeling analyses). However, the benefits are that the
resulting number of sources contacted can be greatly reduced and the quality and detail of the
data received are usually better.
Emissions-Based Approach
Emissions-based questionnaires request information often included in annual volatile organic
compound (VOC) or particulate matter emissions inventories.
The agency may request permitted or potential emissions per source and/or actual emissions,
average emissions, or emissions per day. They may also specify emissions per hour (or time
interval) for specific compounds. In many cases some of this information can be collected for
the majority of sources from the established criteria emission inventory records. The agency may
also ask for emergency episode emissions, fugitive emissions, and information from excluded
criteria emission inventory sources.
M-3
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Chemical Use Approach
Chemical use questionnaires are directed toward lists of specific compounds and ask for process
input information and Material Safety Data Sheets (MSDS). The Material Safety Data Sheets
include the needed species composition data and should be requested where available, for any
approach used. The agency can require the source to contact the suppliers of chemicals they use,
if MSDS are not available. The agency can use these data to make emissions estimates if
information is also provided on daily use, process operating parameters, and efficiency of the
control equipment.
General Approach
This type of questionnaire may be used as input to simple screening models to determine if a
particular source is a potential problem and if further, more detailed source, emissions, and
modeling data are required. A list of chemicals is provided and the sources must access it if it
emits any of the listed compounds. These questionnaires may list minimum levels for each
compound addressed. Such questionnaires may also be used in conjunction with several source
specific questionnaires. The general questionnaire may also be sent to a variety of manufacturing
or industrial process facilities not covered by the source specific questionnaires.
Industry-Specific Approach
These are very detailed questionnaires that may include emissions information from process
vents, fugitive equipment leaks, equipment openings, raw material/product storage and handling,
secondary waste treatment, and liquid spills. Questionnaires of this type are usually focused on a
handful of very large, singularly important point sources. A great deal of pre-screening effort
would be required for industry-specific questionnaires, and a great deal of effort would also be
required of the recipient in filling out the questionnaire. More effort would be required per
source for the agency to properly interpret the response. However, this level of detail is probably
the next best thing to actual source testing in estimating emissions. This technique may also
prove useful in targeting particular sources the agency determines may or may not need to
conduct source tests.
Tiered Approach
In the tiered or staggered mail-out approach, a cover letter and screening study type questionnaire
are used, followed later by more detailed questionnaires sent to a select number or type of
sources. A phone survey may be conducted by the agency prior to the screening study to narrow
the number of facilities to send the screening study questionnaire or the detailed questionnaire.
Whether the phone survey is conducted before or after the screening study questionnaire is sent
depends on the number and type of facilities in the inventory area.
M-4
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A good example would be dry cleaning establishments. The state manufacturing guide may list
100 dry cleaners in a certain city. However, after a phone survey the agency found that
75 percent of these locations are only drop-off and pick service centers. By conducting the phone
screening, it was obvious that no questionnaires were necessary for those service centers. A
more detailed questionnaire was sent to the remaining 25 dry cleaners. This benefitted both the
agency by not having to review unnecessary forms, and the excluded service centers by not
wasting their time completing unnecessary forms. Phone screening may not always be an
efficient use of agency time, depending on the individual agency needs or types of industries
included.
Another approach is to first send an open-ended questionnaire or general questionnaire, followed
by later designed industry specific (by source type) questionnaire, followed-up by phone calls to
clarify data and/or source tests or inspections.
M-5
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M-6
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OTHER CONSIDERATIONS
Other considerations when developing a questionnaire are more related to strategy for
maximizing accuracy and minimizing cost and time involved to conduct an inventory. These
include discussions of the importance of the following:
• Asking the right questions;
• Maximizing return rates;
• Providing for facility confidentiality of trade secrets;
• Outlining what questions are applicable for particular source categories;
• Designing question/answer style and format to decrease confusion or
misrepresentation;
• Providing written instructions for answers (especially units of measurement) with
computer coding format instructions if necessary; and
• Developing a data quality assurance procedure.
Some of these considerations are clearly technical in nature, but they need to be incorporated
with administrative and procedural considerations for the whole effort to be the most efficient.
The Right Questions
A successful questionnaire obtains the right answers to the right questions for the particular
agency while maintaining a good working relationship with the recipients. Duplication of
information already available through permit files may not be needed if the number of sources
included in the survey is few and the information is easily extracted from other sources.
However, for large survey efforts, it may be too time consuming for agency personnel to extract
needed available information and thus, some duplication of effort on the part of the sources
cannot be avoided. If the sources being sent questionnaires are the same as included in the
criteria pollutant inventory, all information which the agency already has about the recipient's
facility, such as mailing address, SIC number, UTM coordinates, emission point numbers, etc.,
should be preprinted on the questionnaire. The agency could use a window envelope to expose
the facility name and address and avoid making additional mailing labels.
M-7
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The Return Rate
The return rate of a questionnaire depends on several factors. The first impression of the
recipient, the simplicity of the questionnaire, and conveying the importance of returning the
questionnaire are all important factors affecting the return rate.
Minimize Questionnaire Length
The recipient's first impression will be based on the size of the questionnaire. It should be as
brief as possible. Unfortunately, it may be impossible for the forms and accompanying
instructions for a large listing of toxic compounds or source categories to be brief. So, the next
best approach may be to design the forms in such a way to make the pages as uncluttered and
readable as possible leaving ample room for answers.
Maximizing Return Rates
Staggered mailing is particularly important for very large inventories, because 1000 or more
questionnaires returned simultaneously may be too difficult to process at one time. Staggered
return uses the agency's limited manpower and resources more economically. Questionnaires
can easily become lost or damaged if they are not processed expediently by the agency, and this
may be less likely to occur if the staggered mailing approach is used.
Each respondent should have an equal amount of time to respond to questionnaires when using
the same format and approach especially if there is a penalty for late responses. But this must
depend on equal complexity of the information required by questionnaires. Obviously more time
will be needed for a large source to complete a source specific questionnaire than a simple
screening survey or a general information questionnaire with, for example 20 compounds versus
200 compounds. Therefore, the time period allowed for completion of emission inventories
require more planning than criteria pollutant inventories. The time period should be long enough
so that the respondent is not overly rushed and short enough that the respondent does not
procrastinate in responding.
Another good approach for a large inventory is to classify the mailings according to priority
chemicals, source type, source size, county locations, or simply a source name (alphabetical)
staggered approach. In this way, all of the questionnaires will not be returned as the same time.
Each questionnaire should be reviewed as soon as possible after it is received. When this
approach is used for a selected small number of sources at the beginning of the update, the
agency can predict the manpower and resources it will take to complete the full-blown inventory
effort. They may find they do not in fact have the manpower to conduct the type of inventory
they want. They can instead rethink and replan their approach or request additional manpower to
complete the inventory.
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Confidentiality
Confidentiality can be established in one of several ways. The simplest is a box to be checked to
request confidentiality for all information other than emissions data given in the questionnaire.
Justification for the request would be given by the recipient on a separate sheet. In this way each
piece of confidential information can be keyed as such.
Another approach would be for the industry to submit one full questionnaire and one "sanitized"
questionnaire that would be available for public review.
The main advantage to this approach is that it clearly indicates the request to the agency. It also
alerts the agency to look for supplementary supporting information. If the questionnaire is
converted to computer input, a check in the confidentiality box can be programmed as a
command to store all information in a limited access data file.
The disadvantages of this approach are that it does not provide confidentiality for only specific
pieces of information and that it may be too easy to use. It should be used only for recipients
who are anticipated to be deeply concerned about confidentiality. This judgment is best handled
by the appropriate agency officials. A better method may be to require the industry to highlight
each and every answer it deems confidential.
A more complex method for establishing confidentiality involves the assignment of a survey
number to each questionnaire; this number would also be printed on the general information
page. The agency director would detach the general information page from the returned
questionnaire and store it in a locked file. Since all identification is presented on the general
information page, no one would be able to associate the information on the question pages with a
specific facility. If necessary, a facility could be identified by locating the survey number in the
locked file of general information pages. This consideration is especially important if the agency
subcontracts to a private consultant for the interpretation and transcription of the information. If
the information is computerized, the identification information could be entered into a separate
limited access file.
Each agency should be versed in their local laws to ascertain that the concealment of
identification is not forbidden (the public access to records varies among states).
A system which allows for partial confidentiality could be established in the cover letter using a
paragraph similar to the following:
Any proprietary information, which you believe is of a confidential nature, should be identified
in a supplementary letter with applicable data in the questionnaire marked with the word
CONFIDENTIAL. A brief explanation in your letter for the desired confidentiality should be
included.
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This system indicates clearly to the agency which information is confidential and which is not. It
also alerts the agency to look for supplementary supporting information with each returned
questionnaire that is marked anywhere with the word "CONFIDENTIAL." However, unless the
marking is very clear, this system can become tedious and inefficient.
Applicability and Clarity of Questions
Several factors in the design of the question section can determine the efficiency of the mailing
and affect the return rate as well. First, there should be a clear statement from which the
respondent can determine whether the questionnaire is applicable to his facility. Second, the
questions should be well-arranged and easy to answer.
A clear statement of applicability serves several purposes. If the questionnaire is applicable, the
statement reinforces the necessity of compliance. If the questionnaire is not applicable and
recipient can easily determine it as such, he may be more cooperative in the future when the
questionnaire does apply to him. A maximum return rate for non-applicable respondents is
important because the agency will not have to waste time and money for follow-up and know up
front which facilities are not being inventoried.
The use of a check box for applicability will help the agency distinguish between questionnaires
that are not applicable and the ones that are returned without any response. Examples of
statements of applicability are provided below.
• If this equipment was used at least five (5) days last year, check this box and
complete the questionnaire.
• If this equipment was not used at least five (5) days last year, check this box and
return this form.
• If this equipment has been removed, check this box and return this form.
• If any compound used on the attached table is less than the minimum level listed,
check this box and return this form.
Statements of non-applicability at the beginning of each page or section can be used as an
alternative or supplement to a general statement of applicability. Colored pages may be used to
designate different sections of the questionnaire. By supplying a check box, the agency can
discriminate between pages that were forgotten and pages that were not applicable.
Complexity and Questionnaire Format
As mentioned earlier, the questions must be well-arranged and easy to answer. Brevity enhances
the rate of return. The agency can usually reduce the bulk of the question section by designing
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industry-specific questionnaires instead of general questionnaires. Industry-specific
questionnaires are designed specifically for one particular type of industry, as opposed to general
questionnaires applicable to a whole group of industries. For example, it may be better to send
an industry-specific questionnaire to a dry cleaning establishment and a multipage, general
questionnaire to an organic solvent user.
The consideration of questionnaire format, however, must be balanced against the level of
resources available to the agency conducting the inventory. It takes more money and manpower
to design, mail out, and interpret industry-specific questionnaires than it does general
questionnaires. Processing of industry-specific questionnaires is also more complex because the
format of each questionnaire will vary. Furthermore, it is possible to send an inappropriate
industry-specific questionnaire to a facility. On the other hand, general questions may be
preferable if the agency's resources are limited or if the agency is unfamiliar with many of the
sources. Inventories for specific pollutants may be most advantageously conducted with general
questionnaires. Furthermore, general questionnaires may be more appropriate for large or
complex facilities that are difficult to characterize. Most of these facilities will have engineers
available to translate their process and emission information onto the forms.
If a general questionnaire must be used, it is important to provide a statement of applicability for
each page. In addition, questionnaires that are organized so that all information about each
emission point can be provided on one page are usually easier to fill out than questionnaires that
have separate pages for process, emissions, control equipment, and stack information
(subject-by-subject). For this reason, source-by-source questionnaires are usually considered the
better format. However, if the questions are arranged by subject, industry-specific questionnaires
can be designed by simply selecting the subject pages that apply to each industry. Then only a
few supplementary pages of questions that are unique to an industry must then be formulated.
Another method that can minimize the level of effort required from the recipient, and therefore
enhance the return rate, concerns the format of the questions. Multiple choice questions are the
easiest type for recipients to answer. Many questions can easily be formatted as multiple choice.
For example, a question that asks the recipient to describe or name the type of control device
used can be improved by supplying a list of conceivable control devices and asking the recipient
to put a check next to the appropriate answer. When needed, multiple choice questions can
include the choice "other" with a blank beside it for entering out-of-the-ordinary controls. Other
questions, such as those that require exact numerical answers, can only be answered
appropriately with a written response. If there are repetitive questions, the recipient could be
asked to make a copy of a questionnaire for each point source or substance being inventoried.
Clarity of Instructions
To be considered accurate, questionnaire responses must provide both the descriptive
information desired and the correct numerical data. Every effort must be made not to confuse the
recipient. Therefore, it is important to provide clear, complete instructions to decrease the
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chances of error in the responses. Instructions should be as concise as necessary. Units of
measurement, method of calculations and conversions, and code number instructions should be
put on the questionnaire itself and not explained in the instructions. This enables the recipient to
read through instructions expediently without becoming caught up in too much detail.
In conclusion, general instructions should be as precise as possible. Some of the most effective
questionnaire instructions are those which explain in detail how to answer each question. If a
particular question requires special clarification, it is best to note special instructions on the same
page as the question rather than print them on a separate instruction page.
The following types of information should be included when asking detailed questions:
• Specific Responses—printing the type of units wanted for an answer right next to
the answer space. Using the multiple choice format;
• Samples-providing completed samples with the instructions for process flow,
schematic and plant layout diagrams. Sample diagrams help the recipient to
visualize what is expected; they are easiest to interpret if they are adjacent to the
instructions;
• Standardized Forms—providing standardized forms when periodic inventory
updates are performed. Regular recipients will eventually learn how to provide the
correct responses. This is one condition under which a single generalized form for
all facilities is efficient;
• Emissions Estimates—instructions for the inclusion of estimation methods used.
Examples of estimation methods include: material balance, emission factors,
source test results, models, and engineering judgments.
Final Considerations
After a questionnaire is designed, it is good quality assurance procedure to check its
effectiveness. This can be accomplished using a limited pilot mailing followed by site visits.
This procedure provides a check on the effectiveness of the particular questionnaire package and
its applicability to different sources. A final possibility that may improve industry-agency
relations would be to include a few questions at the end of the questionnaire or on a separate
page for industry suggestions for future questionnaires or questions such as the following:
• Were the questions clear?
• Approximately how long did it take to complete the form?
• Were the questions applicable to your company?
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• If you called for help and/or agency clarification, did we adequately respond?
• Was the time allowed after receiving the questionnaire adequate? If not, why?
• Please provide additional comments, if any.
This type of addition may indicate to the recipients a true concern to minimize industry
paperwork, or at least the desire to work with industry to improve future questionnaires.
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FOLLOW-UP PROCEDURES
Follow-up can be as important or more important than the planning and effort expended in
questionnaire design. The accuracy and completeness of responses must be checked and
tabulated, and entered into a computer. Depending on how thorough the questionnaire
instructions were explained with the mail-out, and whether deadlines were identified in the cover
letter, a second major effort may be required to contact recipients who are delinquent in
responding or to clarify items such as emissions units or estimates of control efficiencies. Some
second effort can be expected, either for clarification of answers or for non-response. The
following sections discuss the importance of such follow-up procedures such as data quality
checks, the use of on-site inspections, and recontacting sources. Questionnaire revisions are also
discussed.
Quality Control of Data
All the questionnaires should be checked by engineers, chemists, or experienced environmental
scientists to determine if the data provided are reasonable. It is helpful to ask for process flow
and plant layout diagrams to aid in the interpretation of data. In addition, the best quality check
would be performed by engineers or scientists who have worked in or are familiar with the
industry. Finally, for similar processes and chemicals, total emissions can be compared against
each other or checked against appropriate emissions factors to determine reasonableness. The
extent that detailed checks can be done depends on the resources available to the agency, the
number of sources included in the inventory, and the use of the data. It is suggested to recontact
a higher percentage of respondents that considered their usage lower than specified yearly
amount, or as having no toxic emissions when their SIC code would suggest otherwise. Perhaps
they only misunderstood the way the instructions were worded, or know their chemicals by a
trade name instead of chemical composition. In any event, a follow-up call may increase the
accuracy of the inventory.
On-Site Inspections
For certain sources, it may be appropriate to consider plant visits if more specific information
needs to be obtained for a particular program purpose, although this approach can become
resource intensive and time consuming. Another approach is to do a preliminary screening and
visit a very small percentage of facilities as part of a data quality control procedure. Also, it may
be wise to visit a representative sample of respondents that checked the "not applicable" box,
especially if the agency determines from cross referencing SIC codes, that the source has a
potential to emit air toxic compounds.
Another less resource intensive approach may be to inspect the facility to check emission
responses during the next regularly scheduled air compliance inspection. Most agencies
periodically inspect major facilities within their jurisdiction. The problems that can be
encountered using this approach is that air inspectors may need additional training before such
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inspections, because most regular air inspections involve criteria pollutants, or at the most select
pollutants associated with NESHAPs or NSPS.
Recontacting Sources
The return rate for the questionnaires can be increased by recontacting recipients that are
delinquent in responding either by letter or by phone. This recontact reminds them that they will
not be forgotten and may be subject to fine, and that a response is necessary. For other
companies that may be confused by some of the questions, recontact provides them with a less
embarrassing way to ask questions. This interaction is the most effective while the questionnaire
is being initially completed, rather than having to return questionnaires to the industries for
corrections. Using a pilot mailing will help get an idea of the average time recipients take to
respond and how many recipients will need to be recontacted. In addition, a pilot mailing can
provide an overview of the effectiveness of the questionnaire before the final mailing is done.
Unnecessary recontacts should be minimized to avoid the possibility of some firms becoming
uncooperative. Inventory efforts, after all, are not a one-time need. Yearly updates may be
necessary.
Revising the Questionnaire
The process of revising the questionnaire should be an evolving process. With each mail-out or
updating of the inventory, the questionnaire or instructions for completing the questionnaire can
be fine tuned or redirected to meet the developing program needs. But, as mentioned before,
industry will become familiar with questionnaire format that is not changed drastically from
mailing to mailing. So, a carefully considered initial design is the best approach, and will reduce
time needed for follow-up.
Some changes can be expected, such as:
• Promulgation of new regulations, stricter source registration requirements, or
changes in reporting requirements;
• More EPA approved emission factors or more available stack test data;
• Increases in the number and types of compounds included;
• Changes in format of questions when agency installs or changes its data handling
system; and
• Changes in control technology and/or control equipment efficiency.
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Other changes may be made because of the widespread occurrence of wrong responses to a
particular question. Still another kind of revision, but one that has much impact, are changes in
various aspects of the inventory process, such as:
• Addition or deletion of the use of screening questionnaires;
• Changes in the cover letter, instructions or confidentiality provisions;
• Changes in the type of questionnaire, such as a change from open-ended to
industry-specific questionnaires;
• Changes in the ways that the agency intends to use the data; and
• Changes in agency budgets and/or resources and manpower available for inventory
efforts.
Perhaps the best way to proceed is not to plan in terms of needed emission inventory
questionnaire revisions, but to continually focus on needed improvements, whatever the reasons
turn out to be.
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Name of Facility:.
Street Address:
City/State:
Contact Person:
Telephone Number:.
Please check the appropriate box describing your operation.
1. Solvent Used Amount Purchased
Annually (gallons)
PERC (Perchloroethylene)
Petroleum (Stoddard Solvent)
Other Petroleum Solvents
CFC-113 (Trichlorofluoroethane)
TCA (1,1,1-Trichloroethane)
Other
Sample Survey Forms for the Dry Cleaning Industry
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For each machine at your facility, please provide the following information:
Load
Capacity
(pounds of
Machine Type garments)
Estimated
Solvent Use Per
Load (gallons of
solvent) Controls in Place
For your entire facility, please estimate the amount of solvent sent for off-site disposal or
recycling:
Solvent Type Estimated (gallons/year)
PERC (Perchloroethylene)
Petroleum Solvents:
TCA (1,1,1 -Trichloroethane
CFC-113 (Trichlorofluoroethane)
Other (please specify):
For your facility, please estimate the average days per week and hours per day that dry cleaning
equipment is operating:
days per week hours per day
Please list the number of employees at this facility:
employees
Sample Survey Forms for the Dry Cleaning Industry (Continued)
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APPENDIX N
SAMPLE QC CHECKLIST
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Inventory Identification.
Assessed By Date
Provide the information requested along with the corresponding resource document [ref] or data. After
completing the checklist, indicate the actions to be taken, deadline for completion, and date the actions are
completed.
SOURCE CATEGORY:
Defined before data collection? [ref] Yes No
Were definitions adhered to during data collection? Yes No
Inclusive of all listed pollutants? [ref] Yes No
POINT SOURCE CUTOFFS:
Identified during data collection? [ref] Yes No
Documented and reported to people involved in area source inventory? Yes No
Report ID Date
SURVEY RESULTS:
Was the response rate determined?
rate Yes No
Was the percentage of missing information per returned survey estimated? Yes No
percent
EMISSIONS CALCULATIONS VERIFICATIONS:
Were nonreactive VOC emissions excluded from each source category
emissions estimates? [ref] Yes No
EPA recommended estimation methodology used? Yes No
Emissions calculations checked? Y ..
checked by date Yes N0
Are equations explicitly shown? [ref] Y N
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REASONABLENESS CHECKS:
Were magnitudes of calculated emissions compared with other source
categories? Identify second source reference or reference location of data in
file, [ref] Yes No
Were magnitudes compared with national/state ranks of source categories? Yes No
compared by date
Were other inventories and/or national averages compared to AIRS? List other
inventories or reference data in master file. Yes No
Were findings reported and documented? Yes No
SOURCE DATA:
Were area source activity data reliability verified using available data sources?
verified by date Yes No
Are emissions factor sources documented? v ..
where Yes N0
Are local emission factors within national range? [ref] Yes No
Were facilities whose emissions and activity levels are known compared against
generic emission factors to check emission factor reasonableness? Y N
compared by date project file no.
Are assumptions documented for scaling-up source category emissions and
seasonal adjustment factor corrections? [ref] Yes No
Were point sources subtracted from area source emissions estimates?
[ref] Yes No
Are point source corrections to area source emission estimates documented in
the category calculations? [ref] Yes No
Use the worksheet on page 3 of 3 to record the actions to be taken in response to any problems found. Set
a deadline for the completion of the action and indicate when the actions are implemented.
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INTERNAL SOURCE CATEGORY CONSISTENCY
AND ACCURACY QUALITY CONTROL CHECKS (Continued)
Actions To Be Taken
Deadline
Completion Date
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N-4
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APPENDIX O
PROCEDURES FOR DEVELOPING, DOCUMENTING, AND
EVALUATING THE ACCURACY OF SPREADSHEET DATA
-------
Procedures for Developing, Documenting, and
Evaluating the Accuracy of Spreadsheet Data
Procedure
To maintain acceptable data quality, it is important to practice adequate QC measures
during the development and review of spreadsheets. The information presented in a
spreadsheet should be evaluated to determine if input data are transcribed correctly,
calculated results are technically sound, and the final results are reported in a manner that
will allow the data to be evaluated.
The procedures to follow when developing, documenting, and evaluating the accuracy of
spreadsheets are described in this appendix. These procedures describe the minimum
standards to be maintained to help ensure data quality and reproducibility. An example
spreadsheet (with facility identification removed) is presented at the end of this appendix.
Definitions
Spreadsheet - An electronic table that is used to process or present data. A spreadsheet
can be used to store and manipulate data, as well as present data in report-quality, tabular
format.
Spreadsheet Developer (Developer) - The person responsible for the overall accuracy and
quality of a spreadsheet. The Developer ensures that data are entered correctly and that
mathematical functions are accurately executed.
Technical Reviewer - The person not associated with the development of the spreadsheet
that is technically qualified and responsible for verifying the accuracy, completeness, and
reasonableness of the data in the spreadsheet.
Quality Assurance CoordinatorrOAC) - The person that ensures that QC checks and
technical review are performed on the spreadsheet.
Summary of Responsibilities
The Spreadsheet Developer:
• Describes the development of the spreadsheet in the project notebook or in a
memorandum to the project file.
• Ensures that all original data are transcribed (entered) to the spreadsheet correctly.
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• Ensures that all equations used to generate results are entered correctly; ensures
that all equations are used appropriately.
• Ensures that all conversion factors and constants used in equations are described.
• Ensures that all sources of original data are referenced in the spreadsheet.
• Ensures that all variables within equations are defined.
• Ensures that all supporting documentation for the information provided in the
spreadsheet is obtained and submitted to the project file; ensures that memoranda
summarizing procedures, activities, etc., are also maintained in the project file.
• Keeps a log of spreadsheet revisions. If different versions of a spreadsheet are
created, the Developer maintains a log that describes the changes made to the
different versions and maintains a historical file of the spreadsheet(s).
• Locks and protects the spreadsheet when giving the electronic file to reviewers. If
the spreadsheet is being given to someone who will make revisions or enter data,
data cells that should not be changed should be locked. Locking data cells in this
manner will help prevent inadvertent changes to the spreadsheet.
The Team Manager or Leader:
• Determines when the use of spreadsheets (rather than database technology) are
appropriate.
• Determines if a specific format must be used and specifies what information
should be included in each spreadsheet.
• Reviews and approves the procedure for spreadsheet development.
• Ensures that these procedures are followed.
• Ensures that methods and technical approaches used to produce a desired result
are technically sound.
• Assigns adequately trained staff to develop and review the spreadsheet.
• Specifies the level of detail to follow in reviewing the spreadsheet.
• Determines the level of QC necessary. For example, the Team Manager or Leader
must decide if all data points and all calculations should be checked, or if only a
O-2
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percentage should be checked. It may be appropriate to initially check a
percentage and, based on the number of discrepancies identified, decide if
additional QC is required.
• Considers the data quality objectives of the work (how will the data be used?), the
complexity of the calculations, and experience level of the data generator.
• Specifies the level of detail to be included in the spreadsheet documentation.
• Ensures that spreadsheet documentation is included in the project file.
• Assigns a project assistant to organize and maintain a project file.
• Provides guidance on how to present data in the spreadsheet.
The Technical Reviewer:
• Verifies that the Developer's technical approach is reasonable and logical.
• Verifies that documentation is complete and clear.
• Ensures that assumptions and procedures used are reasonable.
• Provides timely, constructive, and direct comments to the Developer.
• Verifies (manually recalculates) at least one result at both low and high extremes
as well as a result around the mid-point of the two.
• Verifies at least one calculation for each equation or combination of equations
used.
• Verifies the accuracy of total values, means, and statistical evaluations of the data.
• With the Team Manager or Leader, determines the amount of data to check; the
number of errors found will dictate the amount of data evaluated for accuracy.
The higher the error rate, the more data points to be checked. If numerous errors
are found, the spreadsheet should be returned to the data generator with a note that
includes a description of the review procedure and percentage of errors found.
The error rate is a good indicator of the accuracy of all of the information in the
spreadsheet. If needed, the QA Coordinator should be consulted for guidance in
determining the most effective way to determine which and how many values to
recalculate.
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• Verifies that original data were input correctly.
• Evaluates the technical soundness of methods and approaches used.
• Ensures that equations in the spreadsheet produce the correct result and that
equations were entered into the spreadsheet accurately.
• Ensures that adequate documentation is included in the spreadsheet and that the
documentation supports the data in the spreadsheet.
• Verifies that the source of all original data is referenced and all equations are
explained.
• Notes all discrepancies identified during their QC review.
• Discusses all discrepancies with the Developer and Team Manager or Leader, as
appropriate. Actual spreadsheet errors identified by the Reviewer should be
corrected by the Developer.
• Summarizes the review (provides a written summary of the data checked, the
errors or problems found, and the recommendations for revisions). The summary
should also include the reviewer's name, date of QC review (month/day/year),
name of file, type of data reviewed, and the percentage of each type reviewed.
• Keeps a copy of the written summary along with an electronic copy of the
spreadsheet that was reviewed.
The Quality Assurance Coordinator:
• Ensures that an appropriate Technical Reviewer has been assigned to review the
spreadsheet.
• Reviews the Developer's quality control (QC) plan.
• Ensures that the procedures described here are followed.
Spreadsheet Identification
• Include a title in the spreadsheet, at the beginning. Make the title descriptive
enough to clearly identify the data presented and the project.
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Identify the Developer and the actual date (month/day/year) the spreadsheet was
developed. (Distinguish between the "print" date and the "actual" date the
spreadsheet was finalized.)
Identify the reviewer and the date (month/day/year) the spreadsheet was reviewed.
Include headers or footers that identify the name of the electronic spreadsheet file,
the page number, and total number of pages (e.g., Page 1 of 2), and the date the
spreadsheet was last revised. The name of the disk or drive on which the file is
stored may also be included with the file name. An exception to this procedure is
a report-quality table for inclusion in a report.
Assign a unique name and number to the revised version of the spreadsheet. Add
comments as a footnote to explain what was revised, the date the revision was
made, and by whom.
Spreadsheet Development
Keep the spreadsheet as simple as possible. Clarity is important. Avoid
numerous calculations in one equation.
Identify any constants or conversion factors used.
Identify the source of all information and data. Include as much detail as possible
(e.g., table and page number along with the title of the document, where
appropriate).
Describe all equations, using footnotes or a comments field, where appropriate.
(e.g., if gram/kilogram are being converted to pound/ton, the equation performing
the calculation should be explained as: "Convert g/kg to Ib/ton: 1 g/kg x 1
lb/453.59 g x 1 kg/1,000 g x 453.59 g/lb x 2,000 Ib/ton, which is equivalent to
multiplying by 2"). If detailed descriptions exist in project notebooks, then a
reference to that notebook (e.g., notebook and page number) should be made in
the comments field.
Describe spreadsheet functions (e.g., average, conditional operators [IF
statements]).
Avoid using specific values in equations, except for easily recognizable
conversion factors or constants.
Enter values within a cell. Equations that use the value should reference the cell.
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• When a single equation is used numerous times, it may be desirable to enter the
equation in a cell and reference the cell when the equation is used, (e.g., If
20 data elements are being converted from g/kg to Ib/ton, enter the conversion
equation in one cell and reference the cell 20 times, rather than entering the
conversion equation 20 times.)
• Hand (manually) verify equation cells.
• Protect verified equation cell regions of spreadsheets to avoid accidentally over
writing.
Supporting Data Requirements
The original raw data used in the spreadsheet should be retained in the project file and in
the project archive. Reference all information and published documents used for
spreadsheet development. Where applicable, photocopy the cover/title page and specific
pages of the reference document.
Describe the development of the spreadsheets in the project notebook or in a
memorandum or calculation sheet addressed to the project file. Include the following
information:
• Project name/reference number;
• Purpose/task;
• Data references;
• Problems that may have occurred during the development of the spreadsheet and
how they were eliminated;
• Justification for the technical approach; and
• A description of the data review process and the written comments from the
technical reviewer (signed/dated).
Project Data File Requirements
Include all of the data required to reconstruct the development of the spreadsheet and
determine the accuracy of the information reported. Include the electronic version of the
spreadsheet in the project data file. Maintain an electronic backup copy at an identified
location and in hard copy in the project file.
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Project: Identification of Emission Factors for C02/Coal-Fired Boilers
Developed by: JLJ 06/21/98
Reviewed by: RFD 07/02/98
File name: s:/criteria/cfb_6.xls
TEST REPORT TITLE: RESULTS OF THE NOVEMBER 7, 1991 AIR TOXIC EMISSION
STUDY ON THE NOS. 3, 4, 5 & 6 BOILERS AT THE @@@@@ PLANT
FACILITY:
UNIT NO.:
LOCATION:
COAL EF DATABASE
REFERENCE NO
3, 4,
@@@@
5 & 6
@@@@
5
PROCESS DATA
Oxygen (% v/v) a
Vol. Flow Rate (dscf/m) b
Vol. Flow Rate (dscf/hr)
F-factor (dscf/MMBtu) c
Heat input (MMBtu/hr)
HHV Bituminous Coal (Btu/lb) d
HHV Bituminous Coal (Btu/ton)
Coal Feed Rate (ton/hr)
Coal type e
Boiler configuration e
Coal source e
SCC
Control device 1 e
Control device 2 e
Data Quality
Process Parameters e
Test methods f
Number of test runs g
Run 1 Run 2 Run 3
7.70 7.60 7.80
804,786 788,668 815,076
48,287,160 47,320,080 48,904,560
9,780 9,780 9,780
3,118 3,079 3,134
8,498 8,498 8,498
16,996,000 16,996,000 16,996,000
183 181 184
Subbituminous
Pulverized, dry bottom
Rochelle
10100222
ESPC
None
B
Watertube boilers with economizers and air preheaters
MM 5 metals, PM, PM10, Method 3 for CO2, Method 18 for BTEX
3
a Page 29.
b Page 37.
c 40 CFR Pt 60, App A, Meth. 19
d Page 42
e Page 1.
f Page 1.
g Various pages.
CO2 EMISSION FACTORS
CO2 concentration (%v/v) a
CO2 concentration (ppm) b
CO2 molecular weight
CO2 concentration (Ib/dscf) c
CO2 emission rate (Ib/hr) d
CO2 emission factor (Ib/ton) e
a Page 29
b convert 1/100 to 1/1,000,000
c (concentration,ppm * molecular weight)/385,500,000
d concentration, Ib/dscf * Volumetric flow rate * 60 min/hr
e emission rate/coal feed rate
Date developed: 06/21/98
Date revised: Not applicable
1
3
Run 1
11. 9
0.00119
44
.36E-10
0 .007
.57E-05
Run 2
11 .9
0.00119
44
1.36E-10
0. 006
3 .55E-05
Run 3
11 .60
0.00116
44
1.32E-10
0. 006
3 .51E-05
Avg
#N/A
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APPENDIX P
LIST OF RELEVANT WEB SITES
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List of Relevant Web Sites
Aerometric Information Retrieval System (AIRS) - Main Menu:
Air ClearingHouse For Inventories And Emission Factors (Air CHIEF) CD-ROM:
http://www.epa.gov/ttn/chief/airchief.htmMorder
AIRS/AFS:
http://www. epa.gov/ttn/airs/afs/index. html
AIRSWeb:
http://www. epa.gov/airsweb/sources. htm
Ambient Monitoring Technology Information Center (AMTIC):
http://www. epa.gov/ttn/amtic/
Basic emission inventory preparation procedures:
http://www. epa.gov/ttn/chief/
California Air Resource Board:
http://www. arb. ca.gov/homepage. htm
Clean Air Technology Center (CATC):
http://www. epa.gov/ttn/catc/
Compilation of Air Pollutant Emission Factors (AP-42):
http://www. epa.gov/ttn/chief/ap42etc. html
Dun and Bradstreet Million Dollar Directory:
http://www. dnb. com/
EIIP documents:
http://www.epa.gov/ttn/chief/eiip/
Emission Measurement Technical Information Center (EMTIC) guidance on emission testing:
Emission Measurement Technical Information Center (EMTIC):
http://www. epa.gov/ttn/emtic/
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Envirofact Warehouse
http://www. epa.gov/enviro/indexjava. html
EPA Office of Mobile Sources
http://www. epa.gov/oms
EPA'sEFIG
http://www.epa.gov/ttn/chief/efig/
Factor Information Retrieval (FIRE) Data System:
http://www. epa.gov/ttn/chief/fire. html
Locating and Estimating (L&E) documents:
http://www. epa.gov/ttn/chief/ap42etc. html#LE
OAQPS Emission Inventory (El) Public Forum:
http://www.epa.gOV/cgi-bin/netforum/nei/a/l
Office of Air Quality Planning and Standards (OAQPS):
http://www. epa.gov/oar/oaqps/
Office of Air & Radiation:
http://www. epa.gov/oar/
Office of Research and Development (ORD):
http://www. epa.gov/ord/
Office of Pollution Prevention and Toxics (OPPT):
http://www. epa.gov/opptintr/
STAPPA/ALAPCO:
http://www. 4cleanair. org/about. html
TANKS
http://www. epa.gov/ttn/chief/tanks. html
Technology Transfer Network (TTN):
http://www. epa.gov/ttn/
The Great Lakes Commission:
http://www.glc. org/
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The Aerometric Information Retrieval System (AIRS):
http://www. epa.gov/airs/
The PM Calc and the MECH Models:
http://www. epa.gov/ttn/catc/products. html#software
The TTN CHIEF Forum:
http://www.epa.gOV/cgi-bin/netforum/chief/a/l
The Landfill Air Emissions Estimation Model:
http://www. epa.gov/ttn/catc/products. html#software
Toxic Release Inventory (TRI) data:
http://www. epa.gov/opptintr/tri/access. htm
U.S. Department of Agriculture
http://www. usda.gov/
U.S. Department Of Energy:
http://home.doe.gov/
WATERS and CHEMDAT8:
http://www. epa.gov/ttn/chief/software. html#water8
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