Emissions Inventory Guidance for
Implementation of Ozone and Particulate
Matter National Ambient Air Quality
Standards (NAAQS) and Regional Haze
Regulations
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EPA-454/R-05-001
Emissions Inventory Guidance for
Implementation of Ozone and Particulate
Matter National Ambient Air Quality
Standards (NAAQS) and Regional Haze Regulations
Issued By:
Emissions Inventory Group
Emissions, Monitoring and Analysis Division
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
August 2005
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DISCLAIMER
THIS DOCUMENT HAS BEEN REVIEWED BY THE OFFICE OF AIR QUALITY PLANNING AND
STANDARDS AND HAS BEEN APPROVED FOR PUBLICATION. MENTION OF TRADE NAMES
OR COMMERCIAL PRODUCTS DOES NOT CONSTITUTE ENDORSEMENT OR
RECOMMENDATION FOR USE.
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CONTENTS
Pas
DISCLAIMER ii
LIST OF TABLES AND FIGURES vi
ACRONYMS AND ABBREVIATIONS vii
SECTION 1.0 OVERVIEW 1
1.1 PURPOSE 1
1.2 RELATIONSHIP TO OTHER EPA EMISSION INVENTORY GUIDANCE 2
1.3 RELATIONSHIP TO THE CONSOLIDATED EMISSIONS REPORTING RULE (CERR) . 3
1.4 RELATIONSHIP TO OZONE, PM2 5, AND REGIONAL HAZE IMPLEMENTATION
RULES 3
1.5 SUMMARY OF DOCUMENT CONTENTS 3
SECTION 2.0 REGULATORY REQUIREMENTS, DEFINITIONS, AND SUBMITTAL DATES ... 7
2.1 STATUTORY AND REGULATORY REQUIREMENTS 7
2.2 TYPES OF INVENTORIES 7
2.3 SPECIFICATION OF BASE YEAR 8
2.4 INVENTORY PREPARATION PLAN 10
2.5 INVENTORY APPROVAL 12
SECTION 3.0 EMISSION INVENTORY ELEMENTS 13
3.1 IDENTIFICATION OF INVENTORY USES 13
3.2 COMPONENTS OF THE BASE YEAR AND 3-YEAR CYCLE INVENTORIES 14
3.2.1 Pollutants and Pollutant Precursors to Be Inventoried 14
3.2.2 Identification of Sources and Source Categories to Be Inventoried 16
3.2.3 Geographic Coverage 16
3.2.4 Temporal Basis of Emissions 17
3.2.5 Actual Emissions, Rule Effectiveness and Rule Penetration 17
3.3 INVENTORIES USED FOR TRACKING PROGRESS 19
3.3.1 Specific Provisions for Ozone Reasonable Further Progress Inventories 19
3.3.2 Specific Provisions for PM Reasonable Further Progress Inventories 24
3.4 GUIDANCE FOR CREATING ANNUAL ON-ROAD MOBILE SOURCE EMISSION
INVENTORIES FOR PM2.5 NONATTAINMENT AREAS FOR USE IN SIPS AND
CONFORMITY 25
3.5 MODELING INVENTORIES 26
3.5.1 Temporal Allocation Procedures 26
3.5.2 Spatial Allocation Procedures 27
3.5.2.1 Point Sources 27
3.5.2.2 Nonpoint and Mobile Sources 27
3.5.3 Speciation Procedures 34
SECTION 4.0 DATA REPORTING AND DOCUMENTATION 37
4.1 DATA REPORTING 37
4.1.1 Point Sources 37
4.1.2 Nonpoint Sources 38
4.1.3 Nonroad Mobile Sources 38
4.1.4 Onroad Mobile Sources 38
4.1.5 Biogenic and Geogenic Sources 38
4.1.6 Electronic Data Transfer 39
IV
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CONTENTS (continued)
4.1.6.1 Protocol for Transferring Data Electronically to the EPA National Emission
Inventory (NEI) 39
4.1.6.2 Direct Source Reporting 40
4.2 DOCUMENTATION OF THE INVENTORY 40
SECTION 5.0 EMISSION INVENTORY DEVELOPMENT 43
5.1 AVAILABLE GUIDANCE 43
5.2 NEI 43
5.3 POINT SOURCES 44
5.4 NONPOINT SOURCES 45
5.5 MOBILE SOURCES 51
5.5.1 Onroad Mobile Sources 52
5.5.2 Nonroad Mobile Sources 57
5.6 BIOGENIC AND GEOGENIC SOURCES 60
5.6.1 Biogenic Sources 60
5.6.2 Geogenic and Other Natural Sources 61
SECTION 6.0 QUALITY ASSURANCE 63
SECTION 7.0 REFERENCES 65
APPENDIX A CONSOLIDATED EMISSIONS REPORTING RULE (CERR) A-l
APPENDIX B REVISED RULE EFFECTIVENESS GUIDANCE B-l
APPENDIX C GUIDANCE FOR CREATING ANNUAL ON-ROAD MOBILE SOURCE
EMISSION INVENTORIES FOR PM2.5 NONATTAINMENT AREAS FOR USE IN
SIPS AND CONFORMITY C-l
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LIST OF TABLES AND FIGURES
Tables Page
2.3-1. SIP Related Dates 9
3.5-1. 2002 EMCH Nonpoint Source Spatial Surrogate Data for the United States 28
3.5-2. Four-digit Nonpoint Source Category Codes and the Predominant Nonpoint Source Spatial
Surrogate 30
4.2-1. Outline for Format/Contents for SIP Emission Inventory Reports 41
4.2-2. Statewide Ozone Precursor Emissions by Source Sector 43
4.2-3. Statewide PM10, PM25, and Precursor Emissions by Source Sector 44
5.4-1. Point Sources of Emissions 46
5.4-2. Nonpoint Sources of Emissions 48
5.4-3. Crustal Sources of Emissions 50
5.5-1. Mobile Sources of Emissions 51
5.5-2. MOBILE6.2 Vehicle Classes 54
5.5-3. HPMS Facility Types 57
5.6-1. Natural Source Categories and Pollutants Emitted 60
Figures
3.5-1. Simplified Graphic of a Modeling Domain 28
3.5-2. Example Spatial Surrogate Fractions Corresponding to Figure 3.5-1 30
VI
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vn
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ACRONYMS AND ABBREVIATIONS
ALAPCO Association of Local Air Pollution Control Officials
ASD Assessment and Standard Division
ATREF Area (nonpoint) source temporal cross-reference file
BC Black carbon
BEIGIS Biogenic Emissions Inventory Geographical Information System
BEIS Biogenic Emissions Inventory System
BELD Biogenic Emissions Landcover Databases
BIOME Biogenic Model for Emissions
CAA Clean Air Act
CAMx Comprehensive Air Quality Model with extensions
CARB California Air Resources Board
CB-IV Carbon Bond IV
CDX Central Data Exchange
CEMS Continuous emission monitoring system
CERR Consolidated Emissions Reporting Rule
CFR Code of Federal Regulations
CHIEF Clearing House for Inventories and Emission Factors
CMAQ Community Multiscale Air Quality model
CNG Compressed natural gas
CO Carbon monoxide
CO2 Carbon dioxide
DARS Data Attribute Rating System
DQO Data quality objective
EC Elemental carbon
EDMS Emission Dispersion Modeling System
EDR Electronic data reporting
EIG Emissions Inventory Group
EIIP Emissions Inventory Improvement Program
EMCH Emissions Modeling Clearinghouse
EMS Emission Modeling System
EPA Environmental Protection Agency
EPS Emission Processing System
ETS/CEM Emissions Tracking System/Continuous Emissions Monitoring
FAA Federal Aviation Administration
FHWA Federal Highway Administration
GCVTC Grand Canyon Visibility Transport Commission
GIS Geographical Information System
GLOBEIS Global Biosphere Emissions and Interactions System
GUI Graphical user interface
HAP Hazardous air pollutant
HCs Hydrocarbons
HDDV Heavy-duty diesel vehicle
HDGV Heavy-duty gasoline vehicle
HONO Gaseous nitrous acid
HPMS Highway Performance Monitoring System
I/M Inspection and maintenance
IPP Inventory preparation plan
vin
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ACRONYMS AND ABBREVIATIONS (continued)
LADCO Lake Michigan Air Directors Consortium
LDDT Light-duty diesel truck
LDDV Light-duty diesel vehicle
LDGT Light-duty gasoline truck
LDGV Light-duty gasoline vehicle
LPG Liquid petroleum gas
LTOs Landing and takeoffs
LULC Landuse/landcover
MC Motorcycle
MOVES Multi-Scale Motor Vehicle and Equipment Emission System
MTREF Mobile source temporal cross-reference file
NAAQS National ambient air quality standard
NAICS North American Industry Classification System
NCAR National Center for Atmospheric Research
NEI National Emission Inventory
NEIEN National Environmental Information Exchange Network
NH3 Ammonia
NIF NEI Input Format
NLCD National Land Cover Database
NMHC Nonmethane hydrocarbons
NMIM National Inventory Emissions Model
NMOG Nonmethane organic gases
NO Nitric oxide
NO2 Nitrogen dioxide
NOX Oxides of nitrogen
NONROAD EPA's emissions model for estimating nonroad emissions
OC Organic carbon
OEI Office of Environmental Information
OTAG Ozone Transport Assessment Group
OTAQ Office of Transportation and Air Quality
OTC Ozone Transport Commission
PAR Paraffin
Pb Lead
PC Personal computer
PM Particulate matter
PM10 Particles with an aerodynamic diameter less than or equal to a nominal 10 micrometers
PM2 5 Particles with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers
PTREF Point source temporal cross-reference file
QA Quality assurance
QAPP Quality Assurance Project Plan
QC Quality control
RADM Regional Acid Deposition Model
RE Rule effectiveness
RFP Reasonable further progress
RFG Reformulated gasoline
ROG Reactive organic gases
ROP Rate of progress
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ACRONYMS AND ABBREVIATIONS (continued)
RPO Regional planning organization
RVP Reid vapor pressure
SAEWG Standing Air Emissions Work Group
SAPRC California Statewide Air Pollution Research Center
SAQM SARMAP Air Quality Model
SARMAP San Joaquin Valley Air Quality Study/Atmospheric Utilities Signatures, Predictions and
Experiments Regional Modeling Adaption Project
SCC Source classification code
SIC Standard Industrial Classification
SIP State Implementation Plan
SMOKE Sparse Matrix Operator Kernel Emissions Modeling System
SO2 Sulfur dioxide
SO4 Sulfate
SOX Oxides of sulfur
STAPPA State and Territorial Air Pollution Program Administrators
TCA 1,1,1-trichloroethane
TCEQ Texas Commission on Environmental Quality
TDM Travel demand model
THC Total hydrocarbons
TIP Tribal Implementation Plan
TOG Total organic gases
UAM Urban Airshed Model
U.S. United States
UTM Universal transverse mercator
VMT Vehicle miles traveled
VOC Volatile organic compound(s)
XML Extensible mark-up language
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SECTION 1.0
OVERVIEW
1.1 PURPOSE
This document provides guidance on how to develop emission inventories to meet State
Implementation Plan (SIP) requirements for complying with the 8-hour ozone national ambient air
quality standard (NAAQS), the revised particulate matter (PM) NAAQS, and the regional haze
regulations. It is intended for use by: the United States (U.S.) Environmental Protection Agency (EPA)
Regional Offices; State, local and Tribal air quality management authorities; and the general public. The
guidance is designed to implement national policy on these issues as embodied in: Sections 110(a)(2)(F),
110(a)(2)(K), 110(a)(2)(J), 110(p), 169(A), 172(c)(3), 182(a)(3), 187(a)(5), 301(a) of the CAA (42
U.S.C. § 7410, 7491, 7502, 751 la, 7512a, 7601) and implementing regulations at 40 Code of Federal
Regulations (CFR) part 51, subparts A and Q contain legally binding requirements.
This document does not substitute for provisions or regulations of the Clean Air Act enumerated above,
nor is it a regulation itself. Thus, it does not impose binding, enforceable requirements on any party, nor
does it assure that EPA will approve all instances of its application, and thus the guidance may not apply
to a particular situation based upon the circumstances. EPA and State decision makers retain the
discretion to adopt approaches on a case-by-case basis that differ from this guidance where appropriate.
Any decisions by EPA regarding a particular State implementation plan (SIP) demonstration will only be
made based on the statute and regulations, and will only be made following notice and opportunity for
public review and comment. Therefore, interested parties are free to raise questions and objections about
the appropriateness of the application of this guidance to a particular situation; EPA will, and
State/Local/Tribal agencies should, consider whether or not the recommendations in this guidance are
appropriate in that situation. This guidance is a living document and maybe revised periodically without
public notice. EPA welcomes comments from the public on this document at any time and will consider
those comments in any future revision of this guidance document.
Readers of this document are cautioned not to regard statements recommending the use of certain
procedures as either precluding other procedures or providing guarantees that using these procedures will
result in actions that are fully approvable. As noted above, EPA cannot assure that actions based upon
this guidance will be fully approvable in all instances, and all final actions may only be taken following
notice and opportunity for public comment.
The purpose of this guidance document is to define elements of emission inventories to meet SIP
requirements for complying with the 8-hour ozone NAAQS, the revised PM NAAQS (24-hour and
annual), and the regional haze regulations. For the PM NAAQS, the emphasis in this guidance is on PM
with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers (PM2 5). However,
State/Local/Tribal agencies should continue to inventory PM with an aerodynamic diameter less than or
equal to a nominal 10 micrometers (PM10) as well because the emission factors for PM2 5 are limited and
PM10 emissions may be needed to calculate PM25. The priority elements of emission inventories
emphasize those necessary for compiling and reporting air pollutant emissions to EPA.
This guidance applies to all State air pollution control agencies. In the special case where a SIP
provides for independent jurisdiction for local air pollution control agencies, the guidance also applies to
these local agencies. Through the provisions of the Tribal Authority Rule, Tribes are not required to
develop emission inventories. However, if Tribes choose to develop an emissions inventory that may
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become part of a SIP or Tribal Implementation Plan (TIP) inventory covered by this guidance, the Tribes
are encouraged to follow the provisions of this guidance.
Ozone, regional haze, and a significant portion of PM2 5 are produced in the air by the combination
of pollutants [oxides of sulfur (SOX), oxides of nitrogen (NOX), volatile organic compounds (VOCs),
ammonia (NH3), and carbon monoxide (CO)] from many of the same local emission sources. In addition,
studies such as the Grand Canyon Visibility Transport Commission (GCVTC) report available at
http ://www.westgov. org/wga/publicat/epafin.htm have identified the long-range transport of pollutants as
contributing to ambient air violations and visibility impairment.1 Therefore, this guidance document and
the Consolidated Emission Reporting Rule (CERR), which is included in this document as Appendix A,
emphasize the importance of preparing a single, statewide inventory for all pollutant emissions that
contribute to the formation of ozone, PM25, and regional haze.
1.2 RELATIONSHIP TO OTHER EPA EMISSION INVENTORY GUIDANCE
This document is a guide for State, local and Tribal agencies for submitting their emission
inventories for the 8-hour ozone and PM2 5 NAAQS, and for the regional haze program. It is not a
procedures document covering the methods for compiling and documenting emissions inventories. Thus,
other existing EPA guidance, such as the documents prepared by the Emission Inventory Improvement
Program (EIIP)2, complements this document.
The EH? has developed procedures for compiling and documenting emission inventories for point,
nonpoint, nonroad mobile, onroad mobile, biogenic, and geogenic source categories. The goal of EH? is
to provide cost-effective, reliable inventories by (1) improving the quality of emissions information; and
(2) developing systems for collecting, calculating, and reporting emissions data. The goal is achieved by
developing a set of "preferred and alternative methods" for all inventory associated tasks. This
standardization improves the consistency of collected data and results in increased usefulness of
emissions information. The EH? will reach its goal through development of:
• Preferred and alternative methods for collecting data and calculating emissions;
• Improved reporting systems;
• Procedures for quality assurance (QA) and quality control (QC); and
• More consistent guidance.
The EIIP is a jointly sponsored effort of the State and Territorial Air Pollution Program
Administrators/Association of Local Air Pollution Control Officials (STAPPA/ALAPCO) and EPA, and
is an outgrowth of the Standing Air Emissions Work Group (SAEWG). Funding is provided by State,
local and Tribal agencies through the federal 105 grant programs. The EIIP Steering Committee and
technical committees are composed of State, local, industry, and EPA representatives. The EPA
maintains a web site which provides the documents prepared by EIIP as well as periodic updates on EIIP
activities and products. The web site address is: http://www.epa.gov/ttn/chief/eiip/.
It should be noted that additions and revisions to the EOF guidance documents are ongoing, and the
EIIP guidance currently does not address all emissions categories within all sectors. Additional specific
guidance for preparing emission inventories, where different from the EIIP, is referred to in Section 5,
"Emission Inventory Development" (e.g., for some nonroad categories). The EPA's Emissions Inventory
Group (EIG) also periodically sponsors emission inventory training for State, local and Tribal agency
staff to prepare ozone inventories, and more recently, PM2 5 and regional haze inventories.
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See the following web site address for copies of training presentations used for prior EPA workshops:
http://www.epa.gov/ttnchiel/eidocs/training.html.
1.3 RELATIONSHIP TO THE CONSOLIDATED EMISSIONS REPORTING RULE
(CERR)
The EPA finalized the CERR on June 10, 2002 (FR 67 39602). The CERR, which improves and
simplifies the reporting of emission inventory information, is provided in Appendix A of this document.
The CERR is also available at www.epa.gov/ttn/chief/cerr/index.html. The EPA developed this guidance
document to complement the CERR and to provide specific guidance to State, local and Tribal agencies
on how to develop emission inventories for 8-hour ozone, PM2 5, and regional haze SIPs.
The first triennial emission inventory required by the CERR is for calendar year 2002 and was
due June 1, 2004. The year 2002 has also been designated as the new base year for 8-hour ozone,
PM2 5, and regional haze SIPs (see Section 2.3, "Specification of Base Year"). The 2002 emission
inventory submitted by the State, local and Tribal agencies to satisfy CERR requirements on June 1, 2004,
is not necessarily the same as the 2002 base year inventory for SIP planning (see Section 2.3). It is
anticipated that State, local and Tribal agencies will use their 2002 CERR inventory as an important
resource in preparing their 2002 SIP base year inventory, but because of the different due dates, in many
cases there are likely to be differences in the two 2002 inventories due to corrections and updates. Also,
the SIP inventories are subject to approval requirements by EPA because the inventories can be
considered SIP elements.
1.4 RELATIONSHIP TO OZONE, PM25, AND REGIONAL HAZE IMPLEMENTATION
RULES
Section 2.3 of this document provides details of SIP inventory implementation schedules. Due to
litigation, the implementation of the 8-hour ozone and PM2 5 NAAQS was delayed from the original
schedule. The implementation of the 8-hour ozone and PM2 5 NAAQS will begin in 2005.
Implementation of the regional haze regulations began after they were finalized in the spring of 1999.
Because many of the same sources produce emissions that contribute to ozone and PM25 formation
and visibility impairment, EPA encourages State, local and Tribal agencies to coordinate emission
inventory planning and development efforts for ozone, regional haze, and PM2 5 as they develop their
required inventories. Coordination of emission inventory planning and development efforts will help to
reduce the burden associated with preparing separate inventories, improve the accuracy of emission
inventories through the application of consistent methods, improve regional modeling studies, and
improve coordination of control strategy development.
1.5 SUMMARY OF DOCUMENT CONTENTS
Section 2 of this document summarizes the regulatory requirements for emission inventories for the
8-hour ozone and PM2 5 NAAQS, and the regional haze regulations. This section also provides a brief
overview of the types of inventories that State, local and Tribal agencies will need to prepare for their
SIPs, specifies the year for which the base year inventories are to be prepared, and provides a time line
illustrating the relationship between the schedules for submittal of emission inventories and other SIP
milestones. Section 2.0 also discusses the emission inventory planning and approval process.
Section 3 identifies and explains the key elements needed for ozone, PM2 5, and regional haze SIP
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emission inventories. The topics covered include components of the base year and periodic inventories;
uses of the inventories; defining the pollutants and pollutant precursors, and sources and source
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categories, to be inventoried; geographic coverage of inventories; temporal basis of emissions; application
of rule effectiveness and rule penetration; and modeling inventories. For modeling inventories, this
section explains the procedures by which emissions in a completed base year or projection year inventory
are temporally allocated, spatially allocated, and speciated for use in a photochemical grid model.
Section 4 provides brief definitions and data element reporting requirements for stationary point and
nonpoint, nonroad mobile, onroad mobile, biogenic, and geogenic emission sources, as defined by the
CERR. This section also specifies data reporting and electronic data transfer requirements, and discusses
how the emission inventories submitted by State, local and Tribal agencies are compiled into a
comprehensive emission database at EPA.
Section 5 addresses emission inventory development procedures for the base year and periodic
emission inventories. This section provides an overview of the types of emission sources and pollutants
expected to be considered for inclusion in an inventory, and cross-references existing emission inventory
development procedures by source category and pollutant where available. Section 5 also emphasizes the
importance for State, local and Tribal agencies to collect the best activity data available for their
inventories. The EPA recognizes that emission factors are either currently not available or have higher
uncertainty for some pollutants (e.g., PM2 5 and NH3), and is conducting ongoing research to develop new
and improved emission factors. Therefore, emphasis should be placed on collecting good activity data for
the base year inventory. As emission factors are developed or improved, the factors can be applied to the
activity data to improve emission estimates.
The final section of this document, Section 6, discusses the importance of including QA/QC
procedures in the inventory planning and development process, and the importance of preparing sound
documentation for the inventories.
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SECTION 2.0
REGULATORY REQUIREMENTS, DEFINITIONS,
AND SUBMITTAL DATES
This section reviews the CAA provisions and associated regulations that require State, local and
Tribal agencies to compile and submit air pollution emission estimates to EPA. It also reviews inventory
types, emission inventory base year, Inventory Preparation Plans (IPPs), and the EPA approval process.
2.1 STATUTORY AND REGULATORY REQUIREMENTS
The EPA interprets Section 110(a)(2)(F) of the CAA (codified in 40 CFR 51 Subparts A and Q) as
requiring SIPs to provide for the reporting of criteria air pollutants for all areas under the general SIP
requirements of section 110. In addition, EPA interprets section 172(c)(3) as providing the Administrator
with discretionary authority to require other emissions data as deemed necessary for SIP development in
nonattainment areas to attain the NAAQS. This statutory authority provides a basis for requiring SIPs to
provide for a periodic inventory of PM emissions for PM nonattainment areas. Section 169(A) provides
authority for emission inventories to be required in SIPs developed to protect visibility in Federal Class I
areas.
2.2 TYPES OF INVENTORIES
For the purpose of developing SIPs to demonstrate compliance with the 8-hour ozone NAAQS, PM2 5
NAAQS, and regional haze rule, there are four basic kinds of inventories that are necessary. These four
are the base year, 3-year cycle, rate of progress, and modeling inventories. Because of the increasingly
regional nature of air quality analysis and planning, three of the four types of inventories should be
prepared on a statewide basis. PM2 5 nonattainment areas would develop inventories for the annual and
24-hour PM2 5 NAAQS, as necessary, to reach attainment and meet Clean Air Act requirements.
The base year inventory is the primary inventory from which the other three inventories are derived.
Thus, all inventories should be consistent with data provided in the base year inventory. The CAA calls
for State, local and Tribal agencies to ensure that the base year inventory is comprehensive, accurate, and
current for all actual emissions. The inventory should include emissions estimates from stationary point
and nonpoint sources, onroad mobile sources, and nonroad mobile sources.
Every 3 years State and local agencies are required to develop periodic inventories called the 3-year
cycle inventories based on actual emissions. State and local agencies have the option to report smaller
point sources every three years or one-third of the sources each year. This option is not available for
reporting emissions for a designated base year inventory. The 3-year cycle inventories are used to
measure overall emission reduction trends and meet information requests from the general public. These
inventories will be important to future modeling studies and emissions trading programs.
The SIP planning process requires State and local agencies to demonstrate reasonable further
progress (RFP) toward attainment with the NAAQS and regional haze rule. To meet this requirement, the
SIP must demonstrate how annual incremental reductions in emissions of the relevant air pollutants will
be achieved to provide steady progress toward attainment of the relevant air quality standards. In
this guidance, EPA uses the term "RFP" as the more generic progress requirement, applying to both ozone
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and PM2 5 nonattainment areas, and "rate of progress" (ROP) to denote the specific requirements for ozone
nonattainment areas subject to subpart 2 of part D of Title I of the Clean Air Act. The RFP/ROP
inventory is developed from the base year inventory to (1) calculate the emission reduction target(s) for
the planning area, (2) develop control strategies, and (3) provide the baseline for calculating emission
reductions associated with the implementation of control measures adopted in the SIP. This inventory
accounts for economic growth and emission source controls anticipated to occur from the base year to the
year for which emission reduction targets must be met. This inventory is limited in geographic scope to
the designated nonattainment area and related adjacent areas that may be included in the domain for
emission reduction credits. It is not statewide.
Modeling inventories are required for developing the attainment demonstration. A modeling
inventory, defined as an inventory that will be processed through an "emissions preprocessor," is only
prepared for a specific modeling application. The inventory components specified in this guidance will
support modeling, but do not require a modeling inventory per se. More details on air quality modeling
for SIP applications is available in separate modeling guidance documents. The modeling guidance will
be available on the EPA's SCRAM website (http://www.epa.gov/ttn/scram/) when complete 3.
Previously, modeling inventories were only specifically required for areas performing photochemical
grid-based modeling to demonstrate attainment of the 1-hour ozone NAAQS; however, recent events have
shown that most State, local and Tribal agencies also need access to emissions data outside their borders.
Regional approaches such as the Ozone Transport Assessment Group (OTAG), the Ozone Transport
Commission's (OTC) NOX baseline study, and the GCVTC study have emphasized the need for regional
(multi-State) emission inventories. Regional modeling is expected to become even more prevalent as
areas develop attainment plans for the 8-hour average ozone and the PM25 NAAQS, and to develop plans
and demonstrate progress toward meeting regional haze visibility goals. Thus, needs for multi-State
inventories to support grid-based modeling are increasing.
Countywide emission estimates are needed for all counties. Where a State, local or Tribal agency is
unable to provide this information, EPA's National Emission Inventory (NET) can be used for regional
analyses. State, local and Tribal agencies that are performing modeling analyses generally have to make
emission estimates for more than just a nonattainment area. In the absence of State-prepared emissions
data, the NEI may be used. Without additional State, local and Tribal agency scrutiny, however, the risk
of incorrect air quality estimates is increased.
2.3 SPECIFICATION OF BASE YEAR
The November 18, 2002 EPA memorandum "2002 Base Year Emission Inventory SIP Planning:
8-Hour Ozone, PM2 5 and Regional Haze Programs" identifies 2002 as the emission inventory base year
for the SIP planning process4. This section reviews the guidance presented in EPA's memorandum
available at http://www.epa.gov/ttn/chief/eidocs/2002baseinven 102502new.pdf.
Updated emission inventories are a key element in the overall SIP planning process for the three
programs. The EPA has designated nonattainment areas for the 8-hour ozone NAAQS with an effective
date of June 15, 2004. Nonattainment area designations for the PM2 5 NAAQS were published in the
Federal Register on January 5, 2005, with an effective date of April 5, 2005. Within 3 years after
designations are promulgated, States will need to submit new attainment demonstration SIPs for the new
NAAQS. For regional haze, most State, local and Tribal agencies (i.e., those participating in regional
planning organizations [RPOs]) will have SIPs due at the same time as the PM25 SIPs. Table 2.3-1 is a
summary of the dates for various elements in the SIP process.
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Table 2.3-1. SIP Related Dates
Program
Ozone
Subpart 1 Nonattainment Areas *
Subpart 2 Nonattainment Areas **
PM25
Regional Haze
Designation of Initial
Nonattainment Areas
June 15,2004
June 15,2004
April 5, 2005
December 17,2004
Emission Inventory Due Date
as SIP Element
June 15,2007
June 15,2006
April 5, 2008
December 17,2007
* Subpart 1 nonattainment areas are those whose 1 -hour ozone design value at designation is less than
0.121 parts per million; subpart 1 of the CAA contains the more general planning and control
requirements with attainment deadlines 5-10 years after designation.
** Subpart 2 nonattainment areas are those whose 1-hour design value at designation is greater than or
equal to 0.121 ppm; subpart 2 CAA contains more specific control and planning requirements and
attainment dates between 2007 - 2024 depending on classification. These areas would be classified as
marginal, moderate, serious, severe, or extreme based on their 8-hour ozone design value.
Note that for the Ozone Subpart 2 nonattainment areas that the required emission inventory submittal
is due on June 15, 2006, one year earlier than the SIP for these same areas. This is because the 1990
CAAA required that the initial base year 1990 emission inventory was due two years after enactment and
one year prior to the SIP due date. The logic was that the emission inventories were needed a year before
the SIPs were due so that the emission inventory data would be available to develop the SIP. EPA has
determined that the two year due date for the emission inventory in the 1990 CAAA applies to all
subsequent Subpart 2 designations.
The EPA selected 2002 as the base year for a number of reasons. The 2002 base year harmonizes
dates for other reporting requirements such as the CERR that requires State, local and Tribal agencies to
submit emission inventories for all criteria pollutants and their precursors every 3 years, on a schedule that
includes the emission year 2002. The EPA concluded that 2002 is the appropriate base year for
requirements related to RFP, after considering the statutory and regulatory provisions applicable to each
program. Using the 2002 inventory as the base year will also ensure that the inventory reflects one of the
years used for calculating the air quality design values on which ozone and PM2 5 designation decisions
are based, as well as one of the years in the 2000 to 2004 period used to establish baseline visibility levels
for the regional haze program. This discussion on 2002 as the base year only applies to areas designated
as nonattainment in the initial ozone (June 15, 2004) and PM2 5 (January 5, 2005) designations. For areas
with an effective nonattainment designation in the future, the base year inventory will be for the calendar
year of the most recent triennial inventory as of the date of designation.
Another practical reason for choosing 2002 as the base year has to do with the schedule of EPA's
own work on the NEI. The EPA made its initial version of the 2002 NEI available to the States in March
2004. This preliminary 2002 NEI can be used in 2004 by each State needing emission estimates for
upwind States. The EPA's final 2002 NEI, which will merge and augment the State-by-State inventories
received in 2004, will be ready by the fall of 2005. Depending on where they are in the process, State,
local and Tribal agencies may wish to rely on the newer estimates of upwind-States' emission, and
certainly should at least consider how the emission estimates for upwind States have changed.
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Alternatively, some regional groupings of States may exchange and merge their 2002 inventories directly,
prior to completion of EPA's final 2002 NEI. The EPA will consult with multistate organizations about
the 2002 inventory process so that work is not duplicated unnecessarily.
In most instances, the States will need to include the 2002 base year SIP inventory in the public
hearing process because it has "regulatory significance" as an intergal part of RFP/ROP plans or
attainment demonstration plans. The States may choose to defer the public hearing on the 2002 base year
SIP inventory until such time as public hearings are held for other SIP elements. The States are
encouraged to include their specific Regional Office in the review of the SIP inventories as early in the
process as possible. This should be done to insure that all major issues regarding the inventory are
resolved before holding a public hearing and before an official SIP submittal.
2.4 INVENTORY PREPARATION PLAN
Inventory Preparation Plans are used as a planning tool to guide inventory preparation and ensure that
emission estimates are of high quality and are consistent with CAA requirements. The IPPs provide State
and local agencies with the opportunity to tell their EPA Regional Office how they plan to compile their
emissions inventories and allow EPA to provide feedback to avoid having State and local agencies use
approaches that are inconsistent. Because EPA has attempted to be as flexible as possible on how it
allows State, local and Tribal agencies to meet the CAA inventory requirements, EPA recommends that
State and local agencies submit detailed IPPs which describe how the inventory is developed, what it
includes, and what assumptions are being made. State and local agencies should prepare and submit these
IPPs for annual and 3-year cycle emission inventories. State and local agencies that prepared earlier IPPs
for the 1-hour ozone or the PM10 NAAQS can use these IPPs as the starting point for the 8-hour ozone,
PM2 5, and regional haze IPPs. The IPPs can also serve as standard operating procedures for the State and
local agencies for future inventory preparation and as documentation of inventory procedures to other
neighboring States in regional planning efforts. In addition, the IPPs can be used as the basis for the
emission inventory documentation discussed in Section 4.2.
The IPPs should include descriptions of inventory objectives and general procedures. One of the first
steps in developing the IPP is to define the purpose and scope of the inventory. This includes identifying
items such as the base year for the inventory, the pollutants to be inventoried, the emissions sources and
source categories, the geographical boundaries of the inventory, the spatial and temporal scales of the
emissions, and the application of controls and regulations including rule effectiveness and rule
penetration. The IPPs for inventories that report VOC emissions should include the State's definition of
VOC and what species are included. The IPPs should also contain a schedule or time line for when the
State and local agencies plan to submit their inventories or inventory components to EPA. This
schedule/time line should also show how the inventory preparation or review process will mesh with the
application of these inventories in atmospheric modeling. If the State or local agency plans to submit an
inventory in components (e.g., point sources, nonpoint sources, etc.), the IPP should so indicate, along
with their submittal dates by component. Final submittal dates should be consistent with the ultimate
inventory dates specified by EPA (see section 2.3).
The IPP should contain the following sections, including separate sections to address the point,
nonpoint, nonroad mobile, onroad mobile, biogenic, and geogenic portions of the inventory:
• Introduction
This section includes items such as: a description of the inventory objectives, including how the IPP
is structured, what it contains, who is responsible for the inventory, and who is compiling it; the
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geographic area covered by the inventory (see section 3.2.3); the base year of the inventory (see
section 2.3); the pollutants included in the inventory (see section 3.2.1); and the temporal resolution
of the inventory (see section 3.2.4). In addition, a State should identify counties it excludes from its
inventory because a local authority is responsible for preparing the inventory for the counties or
Tribal area.
• Point Source Inventory
Topics to be discussed in this section include: how point sources are identified and located (see
section 3.2.2); what data collection methods are used; the basis for activity data and emissions
estimates; how control efficiencies are identified and applied; whether rule effectiveness and rule
penetration are applied and their values (see section 3.2.5); and how temporally resolved emissions
are prepared and supplied (see section 3.2.4). A State or local agency should identify any point
sources it excludes from its inventory because the point sources report directly to EPA.
• Nonpoint Source Inventory
This section identifies what nonpoint source categories are included in the inventory (see section
3.2.2), how emissions are estimated, how data are identified and collected, whether rule effectiveness
and rule penetration are applied and their values (see section 3.2.5), how emissions are temporally
and spatially resolved and supplied (see sections 3.2.4 and 3.3), and how double-counting of
emissions is avoided.
• Nonroad Mobile Source Inventory
This section includes details on what nonroad mobile source categories are included in the inventory
(see section 3.2.2), how emissions are estimated, specification of key inputs for the nonroad emission
model used, including parameters such as temperature and fuel characteristics, description of activity
data to replace model defaults such as equipment population and hours of use, how emissions are
temporally and spatially resolved (see sections 3.2.4 and 3.3), and how double counting of emissions
is avoided. If the State or local agency plans to use EPA's NEI estimates for any nonpoint source
categories, these should be specified.
• Onroad Mobile Source Inventory
This section includes the State or local agency's approach for determining vehicle miles traveled
(VMT) (see section 5.5.1), specification of the mobile source emissions model used, specification of
key assumptions for the model, including parameters such as temperature, speeds, existing inspection
and maintenance (I/M) programs, etc., and how emissions are temporally and spatially resolved (see
sections 3.2.4 and 3.3).
• Biogenic and Geogenic Source Inventory
This section identifies what biogenic and geogenic source categories are included in the inventory
(see section 3.2.2), how emissions are estimated, how data are identified and collected, and how
emissions are temporally and spatially resolved and supplied. If the State or local agency plans to
accept EPA's biogenic inventory, which EPA recommends, this should be stated.
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• Documentation Approach
This section describes how the inventory and its procedures are documented and how the data are
stored and managed (see section 4.2). In addition, this section includes information on how the data
are transmitted to EPA (see section 4.1.6).
QA Plan
This section includes a description of the inventory QA program and QA/QC procedures. See Section
6, Quality Assurance, for more details on QA for the SIP inventories.
A QA Plan should always be included as part of the IPP. In circumstances where the more formal
Quality Assurance Project Plan (QAPP) is developed, the QAPP will satisfy the need for the IPP QA
Plan. See Section 6 for specific information on QAPPs. The EIIP document, "Volume 6 Quality
Assurance Procedures and DARS Software"5, has a chapter on a model QA plan for SIP inventories
which should be useful in the preparation of the QA Plan portion of the IPP. See
http://www.epa.gov/ttn/chief/eiip/techreport/volume06/index.html
Each State or local agency should negotiate its IPP submittal schedules with its EPA Regional Office.
The State or local agency and its Regional Office should agree in advance on the time table for submitting
the IPP and the approval process that will be used by the EPA Regional Office. EPA Headquarters and
Regional Offices will work together to promote consistency of IPP review and approval, while allowing
maximum flexibility to the State and local agencies in their inventory preparation process.
During the preparation of their IPPs, State and local agencies are referred to Volume I of the EIIP
guidance available at http://www.epa.gov/ttn/chief/eiip/techrep ort/volumeO 1 /index.html which discusses
emission inventory planning and development.2 Chapter 2 of Volume VI, Quality Assurance Procedures
and DARS software, of the EIIP guidance available at
http://www.epa.gov/ttn/chief/eiip/techreport/volume06/index.html.5. provides additional information on
planning and documentation of inventory development and QA activities EPA developed QC software is
available at www.epa.gov/ttn/chief/nif/. An example of an IPP developed by EPA for the National
Emission Inventory is available at http ://www. epa. gov/ttnchie 1 /net/nei_plan_feb2001 .pdf.
2.5 INVENTORY APPROVAL
State and local agencies should negotiate the emission inventory approval process with their
respective EPA Regional Office. Included in these negotiations should be a discussion on the emission
inventory documentation that will be necessary to support approval. Of the emission inventories that State
and local agencies submit to EPA, those that are deemed to be of "regulatory significance" will require
EPA approval. In general, this means that the approval process will include the emission inventory as a
component of a SIP submittal, or other significant action by the State, that requires EPA review and
approval. In the guidance memo titled "Public Hearing Requirements for 1990 Base-Year Emission
Inventories for Ozone and Carbon Monoxide Nonattainment Areas", September 29, 1992
Mittp://www.epa.gov/ttn/chief/old/memos/ei/phr sep 1992.pdf). EPA established the policy for deffering
the public hearing on the SIP emission inventories and the approval of these inventories until the time the
areas adopt and submit their attainment demonstration and/or RFP plans.
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SECTION 3.0
EMISSION INVENTORY ELEMENTS
The purpose of this section is to identify and explain the key elements to be included in SIP emission
inventories that should be prepared by State and local agencies to comply with the 8-hour ozone NAAQS,
PM2 5 NAAQS, and regional haze rule. If a State or local agency is unclear on how this guidance applies
to its specific situation, it should consult with its EPA Regional Office for clarification. This section
identifies the uses and components of the base year, 3-year cycle, RFP and modeling inventories discussed
in this guidance document. This section also discusses the temporal allocation, spatial allocation, and
speciation methodologies used to process the inventories for input to photochemical air quality models to
enable State and local agencies the opportunity for supplying data to improve the methodologies.
3.1 IDENTIFICATION OF INVENTORY USES
The uses of inventories determine the information that should be included in the inventories. The
emission inventories covered by this guidance document will be used by State and local agencies to
develop their SIPs to demonstrate attainment of the 8-hour ozone NAAQS, annual and 24-hour PM2 5
NAAQS, and regional haze rule. As discussed in section 2.2, these inventories include the base year, 3-
year cycle, RFP and modeling inventories. In the case of PM2 5 nonattainment areas, States would
determine whether inventories are needed for both the annual and 24-hour PM2 5 NAAQS or only the
annual standard, in order to reach attainment for both PM2 5 NAAQS. These inventories will also be used
by regional planning organizations and EPA to support regional and national analyses, which in turn will
be given to State and local agencies to support development of their SIPs.
The base year inventory is the starting point from which the other SIP inventories are derived. One
of its key purposes is to support air quality modeling and control measure analyses to determine the types
and amounts of emission reductions needed to meet RFP/ROP emission reduction targets and demonstrate
attainment. Emissions trading programs could also be based on the inventory if emissions trading
programs are adopted as a result of implementing controls. The results of these studies are then used by
State and local agencies to identify the emission sources for control, and to develop and adopt the control
measures that should be included in the overall control strategy for a SIP. The CERR presented in
Appendix A specifies the data elements that State and local agencies should include in their inventories.
Studies have indicated that the long-range transport of precursor emissions contribute to elevated
ozone and PM2 5 levels and visibility impacts in down-wind areas.1 Thus, EPA will support State and
local agencies in conducting regional-scale photochemical modeling for all three of these programs to
provide State and local agencies with a number of critical databases for use in developing their attainment
demonstration and maintenance SIPs. To support this effort, EPA will compile inventories that will
include a blend of inventory data submitted by State and local agencies with inventory data developed by
EPA. The EPA-developed data will be used to fill gaps in State data and for certain source types where
EPA has developed accurate and comprehensive emission estimates (e.g., electric utility sources). The
EPA has developed a NEI Preparation Plan available at
http://www.epa.gov/ttn/chief/net/2002neiplan 081004final.pdf which documents in detail how EPA plans
to use State and EPA-developed data.6 These inventories will be stored in a central repository termed the
NEI database. The EPA will also improve the NEI database for other regional studies as the needs arise.
The NEI database will be updated triennially with the emphasis on incorporating State, local and Tribal
data using the 3-year cycle inventories submitted by State, local and Tribal agencies.
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3.2 COMPONENTS OF THE BASE YEAR AND 3-YEAR CYCLE INVENTORIES
3.2.1 Pollutants and Pollutant Precursors to Be Inventoried
This section identifies the pollutants that should be included in the base year and a 3-year cycle
inventory for the 8-hour ozone NAAQS, PM2 5 NAAQS, and regional haze rule. Because many sources
emit more than one of the precursor pollutants, and because the precursor pollutants have the potential to
be transported across State boundaries, it is important that State, local and Tribal agencies develop a
single statewide inventory of pollutants to support integrated, regional-scale modeling, and control
strategy development for ozone, PM2 5, and regional haze.
For all three applications, the 8-hour ozone NAAQS, PM2 5 NAAQS, and regional haze rule, the
emission inventory should be based on actual emissions.
For the 8-hour ozone NAAQS, the pollutants to be inventoried are VOC, NOX, and CO.
For the PM2 5 NAAQS, the pollutants to be inventoried are primary emissions (including
condensibles) of PM10 and PM2 5, and emissions of SO2, NH3, VOC, and NOX. The EPA is specifying
PM10 emissions to be reported because PM10 emissions are often used as the basis for calculating PM2 5
emissions. While elemental or black carbon (EC/BC) and organic carbon (OC) will be identified in
default speciation profiles, more locally-specific data should be collected where available as an input to
model preprocessing. Where such data are available, they should be provided to EPA to help in
improving EPA's speciation profiles. Certain organic gases have been identified as precursors to
secondary organic aerosols (SOA). Toluene, xylene and ethyl benzene are known to be important SOA
precursors. Additional organic gases may be identified by ongoing research. While these gases will be
identified in default speciation profiles, more locally-specific data should be collected, where available, as
an input to model preprocessing. State, local and Tribal agencies can contact EPA's EIG for more
information.
For regional haze, the pollutants to be inventoried include all of the pollutants and precursor
pollutants identified for ozone and PM25, except for CO.
The 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-
trichloroethane (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. The emission factors used to estimate organic emissions represent nonmethane
hydrocarbons (NMHCs). Because of this it is assumed that inventories do not have methane, and part of
the air quality modeling procedure "automatically" adds back that missing VOC component. Therefore,
inventory preparers should not have to do anything further specific to methane. For SIP purposes, State,
local and Tribal agencies should report VOC as defined by EPA (40 CFR §51.100).
For the purpose of this guidance document, the following definitions for PM apply:
• PRIMARY PM: Particles that enter the atmosphere as a direct emission from a stack or an
open source. It is comprised of two components: Filterable PM and Condensible PM.
• FILTERABLE PM: Particles that are directly emitted by a source as a solid or liquid at stack
or release conditions and captured on the filter of a stack test train.
• CONDENSIBLE PM: Material that is vapor phase at stack conditions, but which condenses
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and/or reacts upon cooling and dilution in the ambient air to form solid or liquid PM
immediately after discharge from the stack. For example, some high molecular weight organic
gases rapidly condense and should be reported as condensible PM.
• SECONDARY PM: Particles that form through chemical reactions in the ambient air well
after dilution and condensation have occurred. Secondary PM is usually formed at some
distance downwind from the source. Secondary PM is NOT reported in the emission inventory.
Rather, secondary PM is calculated by air quality models.
In preparing their PM2 5 SIPs, State and local agencies should report the following:
• Primary PM2 5 (or Filterable PM2 5 and Condensible PM individually. Note that all Condensible
PM is assumed to be in the PM2 5 size fraction)
• Primary PM10 (or Filterable PM10 and Condensible PM individually)
It is preferred that the State and local agencies report the two separate components rather than the
single combined Primary PM values, if known. This information is important to assist in the development
of new emission factors for condensible PM. If only the filterable component is known, report it as
"filterable."
In addition, State, local and Tribal agencies may also choose to report the following:
• Total Primary PM (or Filterable Total Primary PM and Condensible PM individually)
For stationary point and nonpoint sources, the EPA recognizes that emission factors for condensible
emissions and speciated PM are limited, as well as emission factors for many industrial sources of
filterable PM2 5. The EPA is working to improve the quality of existing factors and to develop new factors
as emissions source test data becomes available. The EPA invites State, local and Tribal agencies to
provide EPA with source test data they may collect during the preparation of PM inventories to support
the development of emission factors.
The EPA Reference Methods for filterable PM25 and PM10, condensible PM, and speciated PM are
currently available from EPA's Emissions Measurement Center (http://www.epa.gov/ttn/emc/). The
existing test methods for PM include Methods 5, 17, 201 and 201 A, and 202. Methods 5 and ITmeasure
only total filterable PM and do not distinguish between different size particles or measure condensibles or
speciated compounds. Methods 201 and 201A are similar to Method 17 in that they measure total
filterable mass in the stack, but have a cyclone that measures the filterable PM10 fraction. The EPA has
posted Preliminary Method 4 (http://www.epa.gov/ttn/emc/prelim.html) which is a draft method that is
similar to Method 201A but provides for particle sizing at 2.5 micrometers in addition to sizing at
10 micrometers. However, Methods 201, 201A and Preliminary Method 4 do not measure condensibles or
speciated compounds. Method 202 was developed to measure condensible PM and provides limited
speciation data. This method is used with a filterable PM method to determine the total mass of fine PM.
The EPA is developing a new method for characterizing the total PM10 and PM2 5 mass and allows for
the chemical speciation of the PM2 5 component of emissions. This new method will use air dilution to
cool the sample gas which will allow the same chemical reactions and condensation that occur upon
release from the stack to occur in the sampling system. Because the in-stack filter of Preliminary Method
4 has been removed, separate filterable and condensible masses (total, PM10 and PM25) are not measured.
The method allows for the extraction of aliquots of diluted sample gas using the same filter media and
analytical methods used for the ambient air speciation monitoring network. This method is available on
the Emissions Measurement Center web site as a Conditional Method
(http://www.epa.gov/ttnemc01/news/emchighlights2003.pdf). The method will provide for the
development of emission factors that are more reliable and consistent with ambient measurement methods
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than are available with the existing mix of methods for estimating total fine PM mass emissions and
chemical species released to the ambient air. In addition, EPA is continuing to improve methods for
measuring air emission fluxes from fugitive or nonpoint sources and motor vehicles. Interested parties
should periodically check the Emissions Measurement Center's web site to keep current with EPA's
research on improving source test methods for fine PM.
3.2.2 Identification of Sources and Source Categories to Be Inventoried
The CERR requires that States prepare inventories that include all stationary point and nonpoint,
nonroad mobile, onroad mobile, biogenic, and geogenic emission sources present within each county
within a State. The EPA will be furnishing each State the NEI which should be a good starting point for
estimating nonpoint source emissions. Mobile source emissions should be estimated by using the latest
emissions models and planning assumptions available. The NONROAD model can be used for off-road
mobile sources as appropriate. Even if there are areas within a State that do not have significant
emissions, the State should still prepare a statewide inventory (the State may, however, elect to use the
NEI data for nonpoint sources for those areas).
The EPA anticipates that each State, local and Tribal agency will use data obtained through their
current annual emission source reporting requirements, Emission Statement program, and/or operating
permits program to compile emissions data for its point source inventory. As appropriate, a State, local or
Tribal agency may use these data to meet its reporting requirements for point sources. If emissions data
reported under an operating permits program are used, the State or local agency should ensure that the
emissions represent actual rather than allowable or potential emissions for the base year inventory.
The EPA's EIG maintains the Clearing House for Inventories and Emission Factors (CHIEF) web site
(http://www.epa.gov/ttn/chief/) to provide access to the latest information and tools for identifying
emission sources and estimating emissions of air pollutants and preparing air emission inventories. The
CHIEF web site provides access to the list of point, nonpoint, onroad, nonroad, biogenic, and geogenic
source classification codes (SCCs).
For point source reporting under the CERR, a State is required to specify the Standard Industrial
Classification (SIC) code or the North American Industry Classification System (NAICS) code. The U.S.
Department of Commerce, Bureau of the Census has developed the NAICS to replace the SIC system.
The NAICS was developed jointly by the United States, Canada, and Mexico to provide new
comparability in statistics about business activity across North America. Correspondence tables to map
NAICS codes to SIC codes (or SIC codes to NAICS codes) have also been developed by the Bureau of the
Census (http:7/www.census. gov/epcd/www/naics .html).
Section 5.0 of this document provides tables which list in detail the source categories that EPA
believes are significant sources for the pollutants in the tables. This section also lists the source categories
for which EH? procedures guidance has been developed.
3.2.3 Geographic Coverage
The CERR requires that States prepare inventories for all sources for the entire State regardless of the
attainment status of counties within the State. Even if there are areas within a State that do not have
significant emissions, the State must still prepare a statewide inventory. The State may elect to use the
EPA-supplied NEI for nonpoint sources for those areas. Emissions for nonpoint, nonroad mobile, onroad
mobile, biogenic, and geogenic emissions should be provided at the county level. The geographic location
of emissions for point sources should be defined by their coordinates [i.e., latitude and longitude (decimal
degrees)] .
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Because of the regional nature of the pollutants, statewide inventories are necessary to support air
quality modeling to identify the scale of the pollutant problem (i.e., local versus regional), which in turn
will support evaluation and development of cost-effective control strategies. The CERR in Appendix A
specifies the criteria for defining point sources in attainment and nonattainment areas and the frequency
for reporting point source data. The CERR also specifies the criteria for defining nonpoint, nonroad
mobile, onroad mobile, biogenic, and geogenic sources, and the reporting frequencies for these sources.
The CERR includes reporting requirements for all NAAQS criteria pollutants and precursors, and
references the reporting provisions of the Section 110 NOX SIP Call.
3.2.4 Temporal Basis of Emissions
This section addresses the temporal resolution of the emissions data that should be provided in the
base year and 3-year cycle inventories. Discussion of how emissions are temporally allocated for air
quality modeling purposes is provided in section 3.3.1. Temporal adjustments to annual emissions
included in the inventory are made because of seasonal differences in the rate of emissions or activity, or
to apportion emissions to a particular season or day. State, local and Tribal agencies should consult EIIP
guidance for temporal adjustment procedures. It is important that State, local and Tribal agencies develop
a single integrated annual statewide inventory.
For the 8-hour ozone NAAQS emission inventory, VOC, NOX, and CO emissions should be reported
as actual annual and actual summer weekday. Summer weekday emissions are defined as an average
day's emissions for a typical summer day during the ozone season. Temperature data are provided to the
air quality model by meteorological inputs developed for the specific days which are modeled. This
information, in turn, is used by emissions models to "adjust" initial information provided by the State. It
is only necessary to choose a summer weekday and make note of the diurnal temperature pattern used on a
selected day. The emissions model will make adjustments for temperatures observed on the actual days
which are modeled. For modeling purposes, EPA also urges providing estimates for a weekend day,
which may reflect different activity levels and patterns. Note that in certain situations, weekend emissions
may dominate some episodes, and, therefore, the inventory will be needed to support those analyses.
For the PM2 5 NAAQS and regional haze rule emission inventories, direct emissions (including
condensibles) of PM10 and PM2 5, and the precursor emissions VOC, NOX, SOX, and NH3 should be
reported as actual annual. Temporal allocation of the inventories to other time scales (e.g., daily) will be
made during preprocessing of the inventories for modeling, based on temporal allocation pro files.
Alternatively, the State, local or Tribal agency may choose to include actual temporally resolved
emissions data in its inventory (see section 3.3).
The State, local or Tribal agency should discuss in its IPP its approach for preparing and supplying
temporally resolved emissions.
3.2.5 Actual Emissions, Rule Effectiveness and Rule Penetration
For most SIP purposes, emission inventories should contain estimates of actual emissions to the air
during the relevant time period. Activity throughput, uncontrolled emission factor, and control device
efficiency (if used) obviously are factors that affect actual emissions. Other factors that can cause higher
actual emissions are control equipment efficiency that does not meet specification; process excursions
that bypass controls, exceed control equipment capacity, or reduce control efficiency; operator failure to
properly install and run control equipment; bypassing control equipment during maintenance; and
equipment malfunctions. Reasonable efforts should be made to collect information on these factors and to
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incorporate their effects into the estimates of actual emissions.
The concepts of control efficiency, rule effectiveness, and rule penetration are conventionally used in
formally accounting for such real world factors, as described below.
Control efficiency refers to the percentage reduction in emissions achieved by a control device(s) or a
control practice relative to the no control state. For the purposes of emission inventory preparation,
control efficiency is an overarching term that includes the overall efficiency of multiple control devices.
The term control efficiency also includes capture efficiency for point sources which defines the
percentage of emissions from a source that is treated by a control device(s).
Rule effectiveness reflects the actual ability of a regulatory program to achieve the emission
reductions required by regulation (or perhaps voluntarily adopted). The concept of applying rule
effectiveness in a SIP emission inventory has evolved from the observation that regulatory programs may
be less than 100 percent effective for some source categories. EPA's initial rule effectiveness policy was
limited to the ozone related pollutants and included an 80 percent default rule effectiveness factor. This
current rule effectiveness policy revises the earlier policy; specifically, the 80 percent default is
eleminated and particulate matter related pollutants are now included. Rule effectiveness only applies to
controlled emission sources (point) or source categories (non-point sources). No rule effectiveness
adjustment is needed in cases where controls are not applied or a regulation does not exist. In the specific
case of the 2002 ozone SIP emission inventories, States have the option of choosing to use the orginal rule
effectiveness policy or the new policy. When applied to the 2002 PM2 5 SIP emission inventories, States
have the option of not applying rule effectiveness (the old policy) or, if rule effectiveness is applied, using
the new policy.
Rule penetration is an estimate of the percentage of emissions in a source category that are emitted at
facilities subject to the requirements of a rule. For example, a State may adopt a regulation applicable to
sources that emit more than 1 ton per year of VOC. Within the State, some sources will be below the 1
tpy threshold, and will therefore not be subject to the rule's requirements. Rule penetration is an estimate
of the percentage of emissions emitted by facilities covered by a regulation.
In the Spring of 2004, a workgroup consisting of emissions inventory staff from State, local and EPA
offices convened to review existing rule effectiveness (RE) guidance. Through a series of conference
calls, the workgroup developed recommendations to revise EPA's existing rule effectiveness guidance.
The revised guidance is included as Appendix B to this document.
In summary, the revised guidance continues to recommend that a State or local agency attempt to
gather enough local data to make a refined estimate of rule effectiveness. However, such refined
estimates typically involve the expenditure of a significant amount of resources, for example, to perform
numerous inspections, and therefore are not always feasible. As an alternative, the new guidance provides
inventory preparers with a listing of the factors that are most likely to affect RE, and ranks these factors in
a priority order. Inventory preparers then select a rule effectiveness value from within one of 5 ranges for
point sources, or from one of 3 ranges for nonpoint sources. In using this last methodology, the RE
workgroup recognized that a fair amount of subjectivity will remain in the selection of appropriate RE
adjustments. However, the group believes that selecting a RE value from within the ranges provided will
help minimize this subjectivity, and offers a better means of estimating RE than the prior recommendation
of a blanket use of an 80% default value. The guidance also recommends that inventory preparers review
prior rule effectiveness studies performed by other agencies. EPA plans to compile as many of these
studies as possible and to post them on a on a rule effectiveness page of the CHIEF website. Doing so
may reveal a RE study of a similar source category performed by another State that could help inform the
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selection of an appropriate RE value.
Organizations coordinating the preparation of SIP emission inventories are encouraged to coordinate
the application of rule effectiveness/rule penetration with the responsible EPA Regional Office(s).
3.3 INVENTORIES USED FOR TRACKING PROGRESS
This section of the guidance was written before EPA finalized the requirements for the 8-hour ozone
NAAQS. This section of the guidance is based on EPA's views at the time of publication of this
guidance. This guidance may need to be modified after this rule is promulgated. Prior to any such
modification, however, we strongly recommend that the user of this guidance consult the final 8-hour
ozone rule to determine the effect of this rule on this guidance. The purpose of the progress inventories is
to demonstrate a reduction in emissions from regulated sources from the Base Year to a current year.
Specific progress inventory requirements will be determined on a case-by-case basis and will be
dependant on specific elements in each individual progress plan which is part of a SIP. In general, the
progress inventories will be based on the base year inventory with modifications to accomodiate the
following:
• Geographic Coverage: The geographic coverage would be limited to the nonattainment counties
plus any sources in attainment counties that are covered by the modeling domain used to
demonstrate progress compliance as specified in the progress plan.
• Sources and Source Categories Covered: The sources covered are limited to anthropogenic
sources, both stationary and mobile. Biogenic and geogenic sources should not be included.
• Base Year from which Applicable Emission Reductions are Determined: The progress inventory
should specify the Base Year. In most cases, this will be 2002.
• Milestone Dates for Demonstrating progress: These dates need to be specified in the progress
inventory and will be specific to each progress plan.
• Type of Emissions to be Included in the progress inventory: For past and current years, the
progress inventory should be based on actual emissions. Where projected emissions are used
for future years, State, local and Tribal agencies should use the same type of emissions (actual
or allowable or a combination of actual and allowable) that were used in the modeled attainment
demonstration.
3.3.1 Specific Provisions for Ozone Reasonable Further Progress
Inventories
Pollutants for which emissions must be reduced
Section 182(b)(l)(A) of the 1990 Clean Air Act Amendments mandates a 15 percent VOC emission
reduction, accounting for growth, between 1990 and 1996 for moderate and above ozone nonattainment
areas. Furthermore, section 182(c)(2)(B) of the CAA requires each serious and above ozone
nonattainment area to submit a SIP revision providing for VOC emission reductions of at least 3 percent
per year averaged over each consecutive 3-year period beginning in 1996 until the area's attainment date
(the post-1996 ROP plan). Section 182(c)(2)(C) of the CAA allows for substitution of NOX for VOC
emissions reductions in the post-1996 ROP plan. Generally, with some exceptions according to
transitional variences between the 1-hour and the 8-hour standards, the 8-hour implementation scheme for
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ROP follows similar timing and requirements beginning with 2002 as the baseyear through consecutive
classification areas to the 2024 attainment year for extreme areas.
Temporal basis of emissions reductions
For moderate and higher classified areas, the first RFP SIP must be submitted within 3 years after the
area's nonattainment designation. For areas with a June 15, 2004 effective date, for the 8-hour
designations, the SIP would be due by June 15,2007. This would provide up to 3 years for States to
develop and submit RFP plans, and 1 additional year (until the end of 2008) for control measures to be
implemented. The RFP SIP for any remaining 3-year periods out to the attainment date beyond the first 6
years would be submitted with the attainment demonstration, i.e., within 3 years after designation.
However, since States maintain the flexibility to submit plans early to provide more time for
implementation of their SIP control measures, we recommend that States complete their RFP plans as
expeditiously as practicable after designation to provide as much time as possible for sources to
implement the emission reductions.
Methods for calculating emission reductions
We proposed a methodology for the calculation of RFP target levels of emissions that is based on the
method we developed for the 1 -hour standard, while taking into account our interpretation of CAA
restrictions on creditable emissions and our proposal to use the 2002 inventory as the baseline inventory
for the RFP requirement. The CAA specifies four types of measures that were not creditable toward the
15 percent RFP requirement. These were:
(1) Any measure relating to motor vehicle exhaust or evaporative emissions promulgated by the
Administrator by January 1, 1990;
(2) Regulations concerning Reid Vapor Pressure that would go into effect in 1992;
(3) State regulations submitted to correct deficiencies in existing VOC RACT regulations or
previously required RACT rules;
(4) State regulations submitted to correct deficiencies in I/M programs.
These four types of measures were all expected to result in a decrease in emissions between 1990 and
1996. Of these four types of measures, RACT and I/M program corrections and the 1992 RVP
requirements were completely in place by 1996 and therefore are already accounted for in the 2002
baseline. As a result, they would produce no additional reductions between 2002 and 2008 or later
milestone years.
However, the pre-1990 Federal Motor Vehicle Control Program (FMVCP) will continue to provide
additional benefits during the first two decades of the 21st century as remaining vehicles meeting pre-1990
standards are removed from the vehicle fleet. Because these benefits are not creditable for RFP purposes,
in order to calculate the target level of emissions for future RFP milestone years (i.e., 2008, 2011, etc.),
States must first calculate the reductions that would occur over these future years as a result of the pre-
1990 FMVCP. We proposed three methods to properly account for the non-creditable reductions when
calculating RFP targets for the 2008 and later RFP milestone years.
The calculation methods have been revised to account for NOX and for other emissions models.
These methods are consistent with the requirements of sections 182(b)(l)(C) and (D) and 182(c)(2)(B) of
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the Act.
States must use the following methods to properly account for the non-creditable emission reductions
when calculating ROP targets for the 2008 and later ROP milestone years.AB
(1) Method 1: For areas that must meet a 15 percent VOC reduction requirement by 2008:
(A) Estimate the actual anthropogenic base year VOC inventory in 2002 with all 2002 control
programs in place for all sources.
(B) Using the same highway vehicle activity inputs used to calculate the actual 2002 inventory,
run the appropriate motor vehicle emissions model for 2002 and for 2008 with all post-1990
CAA measures turned off. Any other local inputs for vehicle inspection and maintenance (I/M)
programs should be set according to the program that was required to be in place in 1990. Fuel
Reid Vapor Pressure (RVP) should be set at 9.0 or 7.8 depending on the RVP required in the
local area as a result of fuel RVP regulations promulgated in June, 1990.
(C) Calculate the difference between the 2002 and 2008 VOC emission factors calculated in
Step B and multiply by 2002 vehicle miles traveled (VMT). The result is the VOC emissions
reductions that will occur between 2002 and 2008 without the benefits of any post-1990 CAA
measures. These are the non-creditable reductions that occur over this period.
(D) Subtract the non-creditable reductions calculated in Step C from the actual anthropogenic
2002 inventory estimated in step A. This adjusted VOC inventory is the basis for calculating
the target level of emissions in 2008.
(E) Reduce the adjusted VOC inventory calculated in step D by 15 percent. The result is the
target level of VOC emissions in 2008 in order to meet the 2008 ROP requirement. The actual
projected 2008 inventory for all sources with all control measures in place and including
projected 2008 growth in activity must be at or lower than this target level of emissions.
(2) Method 2: For areas that qualify and must meet an 18 percent VOC emission reduction
requirement by 2008 with NOx substitution allowed, following EPA's NOx Substitution Guidance:
(A) Estimate the actual anthropogenic base year inventory for both VOC and NOx in 2002
with all 2002 control programs in place.
These method assume the use of EPA's on-road motor vehicle emissions model in all States other than
California. All of the methods given here required the user to turn off all post-1990 Clean Air Act measures as part
of the calculation. In EPA's current motorvehicle emmisions model, MOBILE62, this is accomplished using the NO
CLEAN AIR ACT commands as described in the MOBILE6.2 User's Guide (found at
http://www.epa.gov/otaq/m6.htm). Users of future versions of EPA's motor vehicle emissions model should consult
the appropriate User's Guide for the version of the model they are using for instructions on what model command to
use. For California nonattainment areas, the current motor vehicle emissions model is EMFAC2002. Users modeling
Californa nonattainment areas should consult with the EPA Regional Office for information on doind equivalent
calculations in the model and in future versions.
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(B) Using the same highway vehicle activity inputs used to calculate the actual 2002 inventory,
run the appropriate motor vehicle emissions model for 2002 and for 2008 with all post-1990
CAA measures turned off. Any other local inputs for I/M programs should be set according to
the program that was required to be in place in 1990. Fuel RVP should be set at 9.0 or 7.8
depending on the RVP required in the local area as a result of fuel RVP regulations promulgated
in June, 1990.
(C) Calculate the difference between 2002 and 2008 VOC emissions factors calculated in Step
B and multiply by 2002 VMT. The result is the VOC emissions reductions that will occur
between 2002 and 2008 without the benefits of any post-1990 CAA measures. These are the
non-creditable VOC reductions that occur over this period. Calculate the difference between
2002 and 2008 NOx emissions factors calculated in Step B and multiply by 2002 VMT. This
result is the NOx emissions reductions that will occur between 2002 and 2008 without the
benefits of any post-1990 CAA measures. These are the non-creditable NOx reductions that
occur over this period.
(D) Subtract the non-creditable VOC reductions calculated in Step C from the actual
anthropogenic 2002 VOC inventory estimated in Step A. Subtract the non-creditable NOx
reductions calculated in Step C from the actual anthropogenic 2002 NOx inventory estimated in
Step A. These adjusted VOC and NOx inventories are the basis for calculating the target level
of emissions in 2008.
(E) The target level of VOC and NOx emissions in 2008 needed to meet the 2008 ROP
requirement is any combination of VOC and NOx reductions from the adjusted inventories
calculated in Step D that total 18 percent. For example, the target level of VOC emissions in
2008 could be a 10 percent reduction from the adjusted VOC inventory in Step D and an 8
percent reduction from the adjusted NOx inventory in Step D. The actual projected 2008 VOC
and NOx inventories for all sources with all control measures in place and including projected
2008 growth in activity must be at or lower than the target levels of VOC and NOx emissions.
(3) Method 3: For all areas that have used Method 1 above (and therefore do not have a NOx target
level of emissions for 2008) and must meet an additional reduction VOC requirement of 9 percent every 3
years after 2008 with NOx substitution allowed, follow EPA's NOx Substitution Guidance. Each
subsequent target level of emissions should be calculated as an emissions reduction from the previous
target.
(A) Estimate the actual anthropogenic base year NOx inventory in 2002 with all 2002 control
programs in place for all sources.
(B) Using the same highway vehicle activity inputs used to calculate the actual 2002 inventory,
run the appropriate emissions model for VOC and NOx in 2002 and 2008 (previously done in
Step B in Method 1 for VOC but not necessarily for NOx) and 2011 with all post-1990 CAA
measures turned off. Any other local inputs for I/M programs should be set according to the
program that was required to be in place in 1990. Fuel RVP should be set at 9.0 or 7.8
depending on the RVP required in the local area as a result of fuel RVP regulations promulgated
in June, 1990.
(C) Calculate the difference between 2008 and 2011 VOC emission factors calculated in Step B
and multiply by 2002 VMT. The result is the VOC emissions reductions that will occur
between 2008 and 2011 without the benefits of any post-1990 CAA measures. These are the
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non-creditable VOC reductions that occur over this period. Calculate the difference between
2002 and 2011 NOx emission factors calculated in Step B and multiply by 2002 VMT. The
result is the NOx emissions reductions that will occur between 2002 and 2011 without the
benefits of any post-1990 CAA measures. These are the non-creditable NOx reductions that
occur over this period.
(D) Subtract the non-creditable VOC reductions calculated in Step C from the 2008 VOC target
level of emissions calculated previously. Subtract the non-creditable NOx reductions calculated
in Step C from the actual 2002 NOx inventory of emissions calculated in Step A. These
adjusted VOC and NOx inventories are the basis for calculating the target level of emissions in
2011.
(E) The target level of VOC and NOx emissions in 2011 needed to meet the 2011 ROP
requirement is any combination of VOC and NOx reductions from the adjusted inventories
calculated in Step E that total 9 percent. For example, the target level of VOC emissions in
2011 could be a 4 percent reduction from the adjusted VOC inventory in Step C and an 5
percent reduction from the adjusted NOx inventory in Step C. The actual projected 2011 VOC
and NOx inventories for all sources with all control measures in place and including projected
2011 growth in activity must be at or lower than the target levels of VOC and NOx emissions.
(F) For subsequent 3-year periods until the attainment date, repeat the process for VOC. For
subsequent 3-year periods, the adjusted NOx inventory should be based on the difference in
NOx emissions during that 3-year period when all post-1990 CAA measures are turned off,
subtracted from the previous NOx target level of emissions. For example, for 2014, take the
difference in NOx emissions reductions that will occur between 2011 and 2014 without the
benefits of any post-1990 CAA measures. This value is subtracted from the 2011 target level of
NOx emissions calculated in Step D to get the adjusted NOx inventory to be used as the basis
for calculating the target level of NOx emissions in 2014.
(4) Method 4: For all areas that have used Method 2 above (and therefore do have a NOx target
level of emissions for 2008) and must meet an additional reduction VOC requirement of 9 percent every 3
years after 2008 with NOx substitution allowed, following EPA's NOx Substitution Guidance. Each
subsequent target level of emissions should be calculated as an emissions reduction from the previous
target.
(A) Using the same highway vehicle activity inputs used to calculate the actual 2002 inventory,
run the appropriate emissions model for VOC and NOx in 2008 (previously done in Step B in
Method 2) and 2011 with all post-1990 CAA measures turned off. Any other local inputs for
I/M programs should be set according to the program that was required to be in place in 1990.
Fuel RVP should be set at 9.0 or 7.8 depending on the RVP required in the local area as a result
of fuel RVP regulations promulgated in June, 1990.
(B) Calculate the difference between 2008 and 2011 VOC emission factors calculated in Step A
and multiply by 2002 VMT. The result is the VOC emissions reductions that will occur
between 2008 and 2011 without the benefits of any post-1990 CAA measures. These are the
non-creditable VOC reductions that occur over this period. Calculate the difference between
2008 and 2011 NOx emission factors calculated in Step A and multiply by 2002 VMT. The
result is the NOx emissions reductions that will occur between 2008 and 2011 without the
benefits of any post-1990 CAA measures. These are the non-creditable NOx reductions that
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occur over this period.
(C) Subtract the non-creditable VOC reductions calculated in Step B from the 2008 VOC target
level of emissions calculated previously. Subtract the non-creditable Nox reductions calculated
in Step B from the 2008 NOx target level of emissions calculated previously. These adjusted
VOC and NOx inventories are the basis for calculating the target level of emissions in 2011.
(D) The target level of VOC and NOx emissions in 2011 needed to meet the 2011 ROP
requirement is any combination of VOC and NOx reductions from the adjusted inventories
calculated in Step E that total 9 percent. For example, the target level of VOC emissions in
2011 could be a 4 percent reduction from the adjusted VOC inventory in Step C and an 5
percent reduction from the adjusted NOx inventory in Step C. The actual projected 2011 VOC
and NOx inventories for all sources with all control measures in place and including projected
2011 growth in activity must be at or lower than the target levels of VOC and NOx emissions.
(E) Repeat entire process for subsequent 3-year periods until the attainment date.
Creditable emission reductions
Section 182(b)(l) contains provisions that limit creditability toward meeting RFP for certain limited
emission reduction measures required prior to the enactment of the CAA Amendments of 1990. The final
rule for implementation of the ozone NAAQS states that all emissions reductions that occur from all
Federal and any other measures (not otherwise identified in section 182(b)(l)(D)) implemented after the
2002 baseline emission inventory year would be creditable to the RFP requirement. Obviously, reductions
that occur prior to the baseline year would be incorporated into the baseline and could not be credited.
3.3.2 Specific Provisions for PM Reasonable Further Progress Inventories
Overview
As discussed in Section 2.3, under the PM2 5 implementation program, PM2 5 SIPs are due three years
from designation (April 2008 for the initially designated nonattainment areas). The basic requirements of
section 172, subpart 1 of the CAA, state that an area must attain as expeditiously as practicable, but no
later than 5 years after designation. It also states that under certain circumstances, EPA may approve a
request for an attainment date extension of an additional five years. EPA does not intend to impose
additional RFP-related requirements for an area that can attain within 5 years of designation (i.e., two
years after submittal of the attainment demonstration). However, an area that requests an attainment date
extension will need to establish emission reduction milestones for January 1,2010 and, if applicable,
January 1, 2013, for those pollutants with emission reduction measures in the attainment demonstration.
The January 2010 milestones should reflect progress in emission reductions from the 2002 base year
through the 2009 emissions year. Likewise, the January 2013 milestones should reflect progress in
emission reductions from the 2002 base year through the 2012 emissions year. These milestones should
reflect reasonable progress in reaching levels to attain the standards. They should not reflect that a
majority of the emission reductions will occur in the last two years prior to the attainment date.
Pollutants for which emissions must be reduced
The pollutants that may be addressed in the emission inventory for RFP purposes are primary PM2 5,
SO2, NOX, VOC, and ammonia. However, a state's attainment demonstration may not include control
measures addressing all of these pollutants. Thus, for RFP purposes, the state should track changes in
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those emissions addressed in the attainment demonstration. All emissions reductions that occur from all
Federal and any other measures implemented after the baseline emission inventory year would be
creditable to the RFP requirement. Obviously, reductions that occur prior to the baseline year would be
incorporated into the baseline and could not be credited.
Spatial basis of emissions reductions
The tracking of emission reductions through the RFP inventory will vary geographically depending
on the pollutant or precursor. For direct PM2 5 emissions, including emissions of elemental carbon,
organic particles and inorganic particles such as metals and crustal material, RFP should be assessed
based on emissions within the nonattainment area. Direct PM2 5 emissions from sources outside the
nonattainment area should not be considered. Because NOX and SO2 emissions are pollutants that can
lead to regional formation of particle sulfate and nitrate many miles from the source, States may include
sources up to 200 kilometers outside the nonattainment area in tracking RFP and associated emissions
reduction milestones. This policy is consistent with previous guidance issued for the 1-hour ozone
program13. The ozone guidance provides that in their RFP baseline inventories, States at a minimum are
required to include all sources of NOX and VOC emissions from within the nonattainment area. EPA
believes that for PM2 5, it is appropriate to allow for the possibility of crediting SO2 and NOX reductions
outside the nonattainment area because numerous technical studies have generally demonstrated the long-
range transport of sulfates and nitrates.
Any State proposing to take credit for reductions by any NOX or SO2 source located within 200 kilometers
of the nonattainment area will need to include with its SIP submittal appropriate documentation
demonstrating that emissions from the sources outside the nonattainment area contribute to fine particle
concentrations within the nonattainment area. Because of the uncertainty associated with VOC
contributions to PM2 5 concentrations, we do not believe it would be appropriate to extend the policy to
VOC sources located 100 kilometers outside of a PM25 nonattainment area.
The EPA expects that analyses conducted as part of the attainment demonstration will help identify the
most appropriate geographic range of interest for each pollutant. EPA believes that if an area concludes
that controls for a specific pollutant on an alternate geographic scale are more appropriate for reaching
attainment, the area should use that same alternate geographic scale in assessing RFP. In particular, for
each pollutant addressed, the same geographic scale must be used in analyzing the 2002 inventory, the
attainment year inventory, and any RFP milestone year inventories, in order to assure that the milestones
in fact represent RFP on a path to timely attainment.
3.4 GUIDANCE FOR CREATING ANNUAL ON-ROAD MOBILE SOURCE
EMISSION INVENTORIES FOR PM2.5 NONATTAINMENT AREAS FOR USE
IN SIPS AND CONFORMITY
This guidance was developed by EPA's Office of Transportation and Air Quality (OTAQ) for
TJ
Memorandum of December 29, 1997 from Richard D. Wilson to Regional Administrators, Regions I-X re
"Guidance for Implementing the 1-Hour Ozone and Pre-Existing PM10 NAAQS." Located at URL:
http://www.epa.gov/ttn/oarpg/tl/memoranda/iig.pdf-. This policy recognized that VOC emissions up to 100 km and
NOX emissions up to 200 km from the nonattainment area could be relied on for RFP. The specified distances
resulted from discussions of the FACA Subcommittee on Ozone, PM, and Regional Haze Implementation Programs.
Because some stakeholders have expressed concerns about this policy, EPA is in the process of subjecting this policy
to a technical review and may revise it in light of that review.
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estimating on-road motor vehicle emissions to meet state air quality implementation plan (SIP) and
transportation conformity requirements. The guidance has been issued separately by OTAQ and is
available at: http://www.epa.gov/otaq/transp/conforn/policy.htm#sips. This guidance is repeated for the
convenience of the emission inventory community in Appendix C.
3.5 MODELING INVENTORIES
This section explains the procedures by which emissions in a completed base year or projection year
inventory are temporally allocated, spatially allocated, and speciated for use in a photochemical grid model.
By explaining these procedures, it is anticipated that State, local and Tribal agencies will be able to provide
more complete and accurate data to increase the accuracy of the procedures. Note, however, that the
information on preparing gridded inventories is presented for informational purposes. The procedures
described are generally applicable to those applied in common emissions models, including the Sparse
Matrix Operator Kernel Emissions Modeling System (SMOKE), the Emissions Modeling System (EMS-95
and EMS-2001), and the Emissions Processing System 2.0 (EPS 2.0). In this guidance, specific examples
are provided that are consistent with the methods employed by SMOKE.
Specific air quality modeling guidance has been completed. It is titled "Guidance on the Use of
Models and Other Analysis in Attainment Demonstrations for the 8 Hour Ozone NAAQS" and is available
on the EPA's SCRAM website (http://www.epa.gov/ttn/scram/guidance sip.htm#8ozone). This guidance
should be consulted for more specific information in the preparation of modeling inventories.
State, local and Tribal agencies should consult with their modeling staff and EPA Regional Office to
verify the procedures that will be used to process their inventory data for modeling and make adjustments
as needed. Once these decisions have been made, State, local and Tribal agencies should document their
approach in the IPP.
It is possible that State, local and Tribal agencies will need to develop microscale, day-specific
inventories to support air quality modeling efforts. These detailed emission inventories may be developed
for any number of State-specific purposes, including model performance evaluation. The EPA encourages
State, local and Tribal agencies to report emissions data at the highest level of detail available. However,
State, local and Tribal agencies are not required to develop these data for the sole purpose of reporting
them to EPA.
In order to develop high quality modeling inventories, sufficient detail in the specification of source
categories is necessary. For example, in the aircraft sector, if emissions data are available for military
aircraft, commercial aircraft, and general aviation (e.g., civil aircraft), these data should be maintained at
this level of resolution in order to allow for appropriate temporal and spatial allocation of emissions.
Similarly, emissions for other nonroad and nonpoint sources should be reported at the highest level of
resolution available. For the onroad sector, the use of EPA's latest SCC codes allow evaporative and
exhaust emissions to be reported separately. These distinctions should be maintained so that appropriate
speciation profiles can be applied, because the composition of exhaust and evaporative VOC from onroad
vehicles is different.
3.5.1 Temporal Allocation Procedures
Emissions models temporalize annual emissions monthly and/or seasonally, weekly (day of the week),
and diurnally in order to allocate emissions to a given hour. Diurnal (hour of day) allocation is performed
separately for weekdays and weekend days. Alternatively, emissions can be input to emissions models as
daily totals. The following discussion describes the methods used to temporally allocate annual emissions
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to hourly emissions. SMOKE uses the same temporal profile file format for point, nonpoint, and mobile
sources. This file contains all of the monthly, weekly, and diurnal profiles and pro file codes used to
temporally allocate emissions.
SMOKE uses two sets of diurnal profiles: one for weekdays and another for weekend days. In
addition to the temporal profile files used by SMOKE, a temporal cross-reference file is also used.
SMOKE uses 3 different cross-reference files for point, nonpoint/nonroad, and onroad sources. The
information in this file is used to assign source categories to the temporal profiles described above. In
addition to specifying the temporal profiles to assign to a given SCC, the cross-reference files allow for
specification of temporal allocation based on pollutant type. For example, if a source category has
different temporal patterns of NOX and VOC emissions, separate temporal profiles can be assigned to these
pollutants. Also, if emissions vary by State or county within the modeling domain, different temporal
profiles can be assigned at the State or county level.
3.5.2 Spatial Allocation Procedures
To prepare emissions for photochemical modeling, these emissions should be spatially allocated both
horizontally and vertically. Horizontal spatial allocation refers to placing the emissions in the proper grid
cell on the emissions modeling grid to be used in the modeling exercise. Vertical spatial allocation refers
to placing the emissions in the proper layer, that is, the distance into the atmosphere, in which emissions
are deposited. Spatial allocation procedures used for point sources are different than those used for
nonpoint and mobile sources. Procedures used for spatial allocation of point source and nonpoint/mobile
source emissions are described below.
3.5.2.1 Point Sources
Point sources are spatially allocated to an emissions modeling grid by the geographic coordinates of a
stack or facility. Geographic coordinates should be supplied as part of the point source inventory. Some
emissions models can handle either latitude/longitude coordinates or Universal Transverse Mercator
(UTM) coordinates (e.g., SMOKE). For EMS-95, latitude/longitude coordinates must be converted to
UTM prior to input to EMS-95. Emissions models use the geographic coordinates to place the associated
emissions in the appropriate grid cell.
The vertical layer that point source emissions are deposited in is based on the plume rise of the
emissions. The plume rise of emissions is calculated based on the stack parameters supplied in the point
source inventory. Therefore, it is important that State, local and Tribal agencies provide accurate stack
parameters (height, diameter, gas exit temperature, velocity, and flow rate) as part of their point source
inventory submissions.
3.5.2.2 Nonpoint and Mobile Sources
Most nonpoint and mobile source inventories contain countywide emissions. Emissions modeling
grids are not based on political boundaries and in almost all cases they represent smaller areas than
counties. Therefore, countywide nonpoint and mobile source emissions must be allocated to grid cells
prior to photochemical modeling. Figure 3.5-1 shows a simplified modeling grid with the locations of
several emissions sources. This grid has 9 grid cells which are identified by row and column (e.g., grid cell
A,l is in the lower left-hand corner).
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Emission models use spatial surrogates to allocate county-level emissions to modeling grid cells.
Ideally, these spatial surrogates closely approximate both the location and magnitude of the emissions for
the nonpoint or mobile source. For each spatial surrogate, the emissions modeler must specify which
surrogate data best approximate the location of the actual source (e.g., area of specified land use/land
cover, length of roadway, population counts, housing counts). The modeler assigns each nonpoint or
mobile source category to a unique spatial surrogate in a cross-reference file (e.g., residential natural gas
combustion emissions assigned to housing, dry cleaning emissions assigned to population).
Figure 3.5-1. Simplified Graphic of a Modeling Domain (Radian, 2000)
Origin
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For example, single-family housing is often used as a surrogate for residential natural gas combustion.
This surrogate closely approximates the location and magnitude of emissions in residential areas with
natural gas service. On the other hand, emissions are allocated incorrectly to areas that do not have natural
gas service. Often, in the selection of spatial surrogates, there is a trade-off in the quality of the surrogate
based on data availability and the cost of new surrogate data development.
Population has often been used in the past as a surrogate for many source categories, including
emissions from gasoline service stations. In this case, the surrogate is probably adequate for allocating
emissions to a coarse grid (e.g., national or regional 36-square kilometers). However, for fine grids (e.g., 1-
or 4-square kilometers for smaller spatial domains), emissions will be allocated poorly since gasoline
service stations tend to be located in commercial areas as opposed to residential areas. Hence, the
parameters and objectives of the modeling exercise should be considered during the selection or
development of spatial surrogates.
In some cases a surrogate (e.g., agricultural cropland) will not exist in a county although an emissions
estimate for a nonpoint source category (e.g., farm harvesting equipment) may be assigned to the surrogate.
In such a case, the emissions model (e.g., EMS-95) may have the capability to assign a secondary surrogate
(e.g., rural land use). If the secondary surrogate also does not exist in the county, the population surrogate
acts as the default since population covers the entire domain. Figure 3.5-2 shows some example spatial
surrogate fractions calculated for the simplified domain in Figure 3.5-1.
The EPA encourages the use and further development of the most representative data for use as spatial
surrogates. Table 3.5-1 provides 2002 U.S. spatial surrogate information from EPA's Emissions Modeling
Clearinghouse (EMCH). These data include Arc View® Geographic Information System (GIS) shape files
and the associated databases. These data are continually being updated and can be downloaded from
EPA's EMCH web site at http://www.epa.gov/ttn/chief/emch/index.html. The EPA is currently developing
databases of spatial surrogate fractions for the U.S. 4-square kilometer unified grid. See the EMCH
website for more information on these databases and the unified grid.
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Figure 3.5-2. Example Spatial Surrogate Fractions Corresponding to Figure 3.5-1
0,200 I O.200
0.2OO
G
C
* I '
f 1
Jl
d',250
m
a
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Table 3.5-1. 2002 EMCH Nonpoint Source Spatial Surrogate Data for the United
States
Surrogate
(data form)
Agriculture
(polygon)
Airports (point)
Dry Cleaners
(polygon)
Forest (polygon)
Four Mile Urban
Buffer (polygon)
Gas Stations
(polygon)
Golf Courses
(point)
Home Heating Fuel
(polygon)
Landuse (polygon)
Land/Water
(polygon)
Low Intensity
Residential
(polygon)
Mines (point)
Mines (polygon)
National Forest
Areas (polygon)
Description
Data source: National Land Cover Database (NLCD) from the U.S. Geological
Service. Data attributes include: non-agricultural, orchards/vineyards, pasture/hay,
row crops, small grains, and fallow land.
Data source: U.S. Bureau of Transportation Statistics and the Federal Aviation
Administration. Data attributes include facility use (public or private), owner (Air
Force, Navy, Army, Private, Public), commercial enplanements, commuter
enplanements, air taxi enplanements, foreign flight enplanements, total enplanements,
and % of total U.S. enplanements.
Data source: U.S. Census Bureau Zip Code Statistics. Data attributes include total
number of dry cleaners in each zip code, number of dry cleaners by employee size
range in each zip code, and number of facilities per polygon.
Data source: NLCD. Data attributes include: non-forest, deciduous forest, evergreen
forest, mixed forest, and woody wetlands.
Data source: U.S. Bureau of Census. Four mile urban buffer built around each
designated urban area. Data attributes include a buffer code (urban area, urban
buffer, non-urban area) and urban area type).
Data source: U.S. Bureau of Census. Number of gas stations in each Census Block
Group.
Data source: U.S. Geological Survey - Geographic Name Inventory System. Data
attributes include golf course name.
Data source: U.S. Bureau of Census - 2000 Census. Data attributes include total
housing units in each Census Block Group, number of housing units in each Census
Block Group using the following fuels as the primary source of heat: utility (natural)
gas, propane, electricity, fuel oil, coal, solar, other fuel, or no fuel.
Data source: Federal Emergency Management Association. Resolution is 1990
census tract level. Data attributes include: Square footage of various building types
including various residential, commercial, industrial, government, and educational
categories.
Data source: NLCD. Data attributes include land, inland water, and coastal water.
Data source: NLCD. Identifies areas with low intensity residential land use.
Data source: U.S. Geological Service. Data attributes include type of operation and
type of commodity.
Data source: NLCD. Data attributes are either mine area or non-mine area.
Data source: U.S. Forest Service. Data attributes include national forest name.
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Table 3.5-1 (continued)
Surrogate
(data form)
Native American
Reservations
(polygon)
Natural Gas
Facilities (point)
Navigable
Waterways (line)
Oil Facilities
(point)
Population
(polygon)
Population Change
(polygon)
Ports (point)
Railroads (line)
Roads (line)
Timber Harvesting
(point)
Urban (polygon)
Waste-Water
Treatment Plants
(point)
Description
Data source: U.S. Bureau of Census. Data attributes include reservation name.
Data source: Federal Emergency Management Association. Data attributes include
the main function of the facility.
Data source: U.S. Army Corps of Engineers. Data attributes include geographic
class (Great Lakes, Ocean, Inland Waterway), functional class (no traffic, shallow
draft, deep draft, both), waterway type (harbor, intracoastal waterway, sealane, etc.).
Data source: Federal Emergency Management Association. Data attributes include
facility function (tank farm or production plant).
Data source: U.S. Bureau of Census - 2000 Census. Resolution of data is 2000
census tract level. Data attributes include population, housing units, housing density,
and demographic data.
Data source: U.S. Bureau of Census - 2000 Census. Change in U.S. population
between 1990 and 2000. Data attributes include 1990 population based on Census
2000 block groups, 2000 population, and calculated change in population.
Data source: U.S. Army Corps of Engineers. Comprised of major national
commercial shipping ports. Data attributes include number of berths and main
function (type of goods).
Data source: U.S. Bureau of Transportation Statistics - Federal Railroad
Administration. Data attributes include abandoned rail lines, passenger service,
military service, and railroad class type (Class 1, 2, 3, A, O/U).
Data source: U.S. Census Bureau TIGER Data. Data attributes include road classes -
urban primary, rural primary, urban secondary, and rural secondary.
Data source: U.S. Forest Service, Forest Inventory and Analysis Survey. Data
attributes include timber site size, forest type (many species), owner type (various
public and private owners).
Data source: U.S. Bureau of Census. Data attributes include urban area type (urban
area, urban cluster).
Data source: Federal Emergency Management Association. Point locations of waste-
water treatment plants.
A source category code (SCC) to spatial surrogate cross-reference file can also be downloaded from
the EMCH. Because there are over 340,000 State/county/nonpoint source category combinations, it is not
possible to list all spatial surrogate assignments here. However, Table 3.5-2 provides an overview of
assignments contained in the EMCH cross-reference file available in January of 2003. The table identifies
the 4-digit nonpoint source category code (note that nonpoint source category codes are 10 digits long), a
brief description of the nonpoint source category, and the predominant nonpoint source spatial surrogate to
which most of the nonpoint source categories have been assigned. This table is strictly an overview and
does not show many other surrogate assignments that differ at the 10-digit SCC level. See the cross-
reference file located at the EMCH web-site for more detailed assignments. As spatial surrogate data
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improves, changes will continue to be made to the assignments shown in the cross-reference file. For
example, many of the new sources of spatial surrogate data shown in Table 3.5-2 will supplant the current
assignments (e.g., the dry cleaning spatial surrogate data will be used instead of population).
It should be noted that some areas may have link-based VMT data that can be used to develop much
more refined spatial surrogates for onroad mobile sources. The use of link-based VMT spatial surrogates
allocates emissions to specific road segments based on the number of miles traveled on that segment.
Hence, the accuracy of spatial allocation is improved dramatically over allocating emissions to a gridded
roadway length.
Both nonpoint and mobile source emissions are assumed to be ground-level sources, that is, deposited
into the surface layer. Therefore, no vertical spatial allocation is needed for these sources.
Table 3.5-2. Four-digit Nonpoint Source Category Codes and the Predominant
Nonpoint Source Spatial Surrogate
4-digit
Nonpoint
Source
Category
Code
Default
2101
2102
2103
2104
2199
2260
2265
2270
2275
2280
2282
2283
2285
2294
2296
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2325
2390
2399
2401
2415
2420
2425
2430
Major Category Description
(2-digit Nonpoint Source Category)
Default
Stationary Source Fuel Combustion
Stationary Source Fuel Combustion
Stationary Source Fuel Combustion
Stationary Source Fuel Combustion
Stationary Source Fuel Combustion
Mobile Sources
Mobile Sources
Mobile Sources
Mobile Sources
Mobile Sources
Mobile Sources
Mobile Sources
Mobile Sources
Mobile Sources
Mobile Sources
Industrial Processes
Industrial Processes
Industrial Processes
Industrial Processes
Industrial Processes
Industrial Processes
Industrial Processes
Industrial Processes
Industrial Processes
Industrial Processes
Industrial Processes
Industrial Processes
Industrial Processes
Industrial Processes
Industrial Processes
Solvent Utilization
Solvent Utilization
Solvent Utilization
Solvent Utilization
Solvent Utilization
Minor Category Description
(4-digit Nonpoint Source Category)
Default
Electric Utility
Industrial
Commercial/Institutional
Residential
Total Nonpoint Source Fuel Combustion
Off-highway Vehicle Gasoline 2-Stroke
Off-highway Vehicle Gasoline 4-Stroke
Off-highway Vehicle Diesel
Aircraft
Marine Vessels Commercial
Marine Vessels Recreational
Military Marine Vessels
Railroads
Paved Roads
Unpaved Roads
Chemical Manufacturing: SIC 28
Food and Kindred Products: SIC 20
Primary Metal Production: SIC 33
Secondary Metal Production: SIC 33
Mineral Processes: SIC 32
Petroleum Refining: SIC 29
Wood Products: SIC 24
Rubber/Plastics: SIC 30
Fabricated Metals: SIC 34
Oil and Gas Production: SIC 13
Construction: SIC 15-17
Machinery: SIC 35
Mining and Quarrying: SIC 14
In-process Fuel Use
Industrial Processes: NEC
Surface Coating
Degreasing
Dry Cleaning
Graphic Arts
Rubber/Plastics
Predominant
4-Digit Nonpoint
Source
Spatial
Surrogate
Population
Population
Population
Population
Housing
Land Area
Population
Population
Population
Airports
Ports
Water Area
Ports
Railroads
Population, Urban
Population, Rural
Population
Population
Population
Population
Population
Population
Population
Population
Population
Population, Rural
Housing
Population
Population, Rural
Population
Population
Population
Population
Population
Population
Population
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4-digit
Nonpoint
Source
Category
Code
2440
2460
2461
2465
2500
2501
2505
2510
2601
2610
2620
2630
2640
2660
2701
2730
2740
2801
2805
2810
2830
2850
Major Category Description
(2-digit Nonpoint Source Category)
Solvent Utilization
Solvent Utilization
Solvent Utilization
Solvent Utilization
Storage and Transport
Storage and Transport
Storage and Transport
Storage and Transport
Waste Disposal, Treatment, and Recovery
Waste Disposal, Treatment, and Recovery
Waste Disposal, Treatment, and Recovery
Waste Disposal, Treatment, and Recovery
Waste Disposal, Treatment, and Recovery
Waste Disposal, Treatment, and Recovery
Natural Sources
Natural Sources
Natural Sources
Miscellaneous Nonpoint Sources
Miscellaneous Nonpoint Sources
Miscellaneous Nonpoint Sources
Miscellaneous Nonpoint Sources
Miscellaneous Nonpoint Sources
Minor Category Description
(4-digit Nonpoint Source Category)
Miscellaneous Industrial
Miscellaneous Nonindustrial: All Classes
Miscellaneous Nonindustrial: Commercial
Miscellaneous Nonindustrial: Consumer
***UNKNOWN***
Petroleum and Petroleum Product Storage
Petroleum and Petroleum Product Transport
Organic Chemical Storage
On-site Incineration
Open Burning
Landfills
Wastewater Treatment
TSDFs
Leaking Underground Storage Tanks
Bio genie
Geogenic
Miscellaneous
Agriculture Production - Crops
Agriculture Production - Livestock
Other Combustion
Catastrophic/Accidental Releases
Health Services
Predominant
4-Digit Nonpoint
Source
Spatial
Surrogate
Population
Population
Population
Population
Population, Rural
Population, Rural
Population
Population, Rural
Population
Population, Rural
Population, Rural
Population, Rural
Population, Rural
Population
Agriculture
Population, Rural
Water Area
Agriculture
Agriculture
Housing
Population, Rural
Population
3.5.3 Speciation Procedures
Another task performed by emissions models is VOC, NOX, sulfur dioxide (SO2), and PM speciation.
Speciation is necessary in order to disaggregate these inventory pollutant species into air quality model
species. VOC speciation is a 2-step process. First, the models calculate the amount of discrete VOC
species emitted per unit mass of VOC. Second, the models "lump" these discrete species together into
groups of lumped-model species. Additional details of these two steps follow:9
• discrete speciation - refers to splitting emissions for a pollutant into individual chemical
compounds. For example, total organic gas (TOG) emissions from automobile exhaust may
consist of 50 or more identified organic compounds (e.g., benzene, hexane, formaldehyde, etc.).
Discrete speciation is performed using speciation profiles containing weight fractions for each
chemical compound (e.g., profiles found in EPA's SPECIATE database);
• lumped-model speciation - refers to splitting emissions for a pollutant into groups of components
that represent numerous discrete compounds. The groups of components are referred to as
lumped-model species. The lumped-model species for TOG are developed using split factors that
are specific to the type of chemical mechanism employed by the photochemical model to be used.
For example, the Urban Airshed Model (UAM) uses the Carbon Bond IV (CB-IV)
mechanism, therefore discrete compounds are lumped together based on the compounds' carbon
bond structure. The single carbon-carbon bond HC compounds, for instance, are lumped into the
paraffin (PAR) lumped-model species. For the California Statewide Air Pollution Research
Center (SAPRC) mechanism employed by the Regional Acid Deposition Model (RADM) and the
San Joaquin Valley Air Quality Study/Atmospheric Utilities Signatures, Predictions and
Experiments Regional Modeling Adaption Project (SARMAP) Air Quality Model (SAQM),
discrete compounds are lumped together based on their relative reactivity with the hydroxyl
radical.
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For NOX emissions, these are discretely speciated into nitric oxide (NO) and nitrogen dioxide (NO2)
[and sometimes gaseous nitrous acid (HONO)]. The NO and NO2 split factors for NOX are typically based
on an assumed composition of NO (as NO2) and NO2 (e.g., 90 percent NO as NO2 and 10 percent NO2).
However, the NO mass can vary between 89 and 95 percent by weight. Sometimes, HONO mass is also
included in the speciation (usually less than 2 percent of NOX mass). SO2 is discretely speciated into SO2
and sulfate (SO4). Important PM2 5 species include EC, OC, SO4, nitrates, NH3 and organic gases that
contribute to the formation of secondary organic aerosols (SOA). For most sources of PM2 5, sulfates,
nitrates and ammonia make up only a small portion of the total mass. However, EC and OC can make up a
substantial fraction of PM2 5 mass and are important contributors to visibility impairment and fine PM
pollution.
Prior to discrete speciation, a pollutant conversion step is often necessary. The most common example
of this is for VOC emissions. Most speciation profiles have been developed based on TOG instead of VOC
or reactive organic gas (ROG). Therefore, the emissions model will apply a conversion factor to adjust the
VOC (or ROG) emissions to approximate TOG emissions.
During the VOC speciation process, mass-based emissions from the emissions inventory (e.g.,
grams/hour) are converted into the mole-based emissions needed by the air quality model (e.g.,
moles/hour). While VOC speciation can be thought of as three separate steps in some cases (pollutant
conversion, discrete speciation, lumped-model speciation), emissions models often perform these steps in
one calculation by combining discrete and lumped-model speciation.
Other pollutants such as PM2 5 do not require a step similar to the conversion of VOC to TOG. In
addition, unlike the speciation of VOC, PM is not converted to molar values, as the chemistry applied in air
quality models does not currently require it as direct input. For further details on speciation, see EPA's
web site http ://www. epa .gov/ttn/chief/emch/sp eci ation/index .html.
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SECTION 4.0
DATA REPORTING AND DOCUMENTATION
As discussed in Section 2.5 of this document, inventories developed by States will be integral parts of
other SIP planning tools, such as RFP emission reduction plans. Such inventories are referred to as "SIP
inventories", and will need to be subject to a public hearing and approved into the State's SIP in
conjunction with the associated regulatory planning SIP. To reduce the administrative burden, EPA
recommends that the hearing on the SIP inventory be held in conjunction with the hearing on the associated
regulatory plan.
Since the inventories described above will need to be approved into the State's SIP, the methods used
to develop the emission estimates need to be clearly documented in a written report submitted to the
appropriate EPA Regional office. The report should include descriptions and identification of the activity
data and emission factors used, as well as any adjustments made to derive the required temporal basis for
the estimates. States should discuss the timeframe and specific contents of these reports with their EPA
Regional office. During these discussions, the already existing inventory data requirements brought about
by EPA's Consolidated Emissions Reporting Rule (CERR) should be acknowledged to avoid duplication of
effort. Section 4.1 provides an overview of the electronic emission data reporting requirements of the
CERR which covers the data elements that will be necessary for the SIP inventories. Section 4.2 is a
discussion of the written documentation that is needed to support the electronic data discussed in Section
4.1.
4.1 DATA REPORTING
The CERR requires specific data elements to be reported by State and local agencies to EPA for point,
nonpoint, nonroad mobile, and onroad mobile source categories. The following sections summarize
reporting for each of these four major source sectors, as well as biogenic and geogenic emission source
categories. Electronic data transfer options are also discussed. The CERR, including the preamble, is
included as Appendix A to this guidance document and is referenced where appropriate.
4.1.1 Point Sources
Point sources are large, stationary, identifiable emissions sources that release pollutants into the
atmosphere. Sources are generally defined by State or local agencies as point sources if they annually
exceed a specified pollutant emissions threshold. These thresholds may vary by State, but EPA has
established certain minimum point source thresholds for both pollutant nonattainment areas and attainment
areas.
According to the CERR, States are required to report data for larger point sources, or Type A point
sources, on an annual basis, starting with the 2001 inventory. Type B sources refer to all point sources,
including Type A sources. The reporting frequency for Type B sources has been established as once every
3 years, starting with the 2002 inventory.
The pollutant emission thresholds that define Type A and Type B sources are presented in Appendix
A, Table 1. The data elements required to be reported are listed in Appendix A, Table 2a. The emissions
thresholds also vary depending on whether a point source is located in a pollutant nonattainment area or
attainment area (but the data elements are the same regardless of attainment status). It should also be noted
that additional stack data elements, while not required for annual Type A point source reporting, should be
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reported every 3 years.
4.1.2 Nonpoint Sources
Nonpoint sources are sources that do not qualify as point sources under the relevant emissions cutoffs.
Nonpoint sources encompass more widespread sources that may be abundant, but that, individually, release
small amounts of a given pollutant. Examples of nonpoint sources include dry cleaners, residential wood
heating, autobody painting, fires, and consumer solvent use.
Every 3 years, beginning with the 2002 inventory, State, local and Tribal agencies should submit to
EPA nonpoint source emissions data representing all relevant nonpoint source categories for the entire
State. The data elements required for nonpoint source reporting are listed in Table 2b of Appendix A.
4.1.3 Nonroad Mobile Sources
Nonroad mobile sources can be defined as mobile and portable internal combustion powered
equipment not generally licensed or certified for highway use. Nonroad engines can be classified
according to distinct nonroad equipment categories, ranging from small lawn and garden equipment to
heavy-duty construction equipment, large aircraft, and diesel locomotives. These general categories
comprise specific types of applications (e.g., chainsaws, front mowers, and leaf blowers/vacuums are
examples of lawn and garden applications).
Every 3 years, State, local and Tribal agencies should submit to EPA a statewide nonroad mobile
source emissions inventory, starting with the 2002 inventory. Table 2b of Appendix A presents the data
elements required to be reported for nonroad sources (which are identical to those elements required for
nonpoint sources). If State, local and Tribal agencies make changes to the default NONROAD model
inputs, discussed in more detail in Section 5.5.2, these input files should be submitted to EPA along with
the nonroad data elements.
4.1.4 Onroad Mobile Sources
Onroad mobile sources are defined as those vehicles registered for use on public roadways, and
include automobiles, light-duty and heavy-duty trucks, buses, and motorcycles. Onroad emissions are
comprised of both exhaust (i.e., tailpipe) and non-exhaust (e.g., refueling, tire and brake wear) components.
States are required to submit a statewide onroad mobile source emissions inventory on a 3-year basis,
starting with the year 2002. Table 2c of Appendix A presents the data elements required to be reported by
State agencies for onroad mobile sources. The MOBILE model input files should also accompany the
onroad mobile source data, so that these inputs are available for national and regional air quality modeling
studies.
4.1.5 Biogenic and Geogenic Sources
Biogenic and geogenic sources are natural (i.e., nonanthropogenic) emissions sources. Biogenic
sources are biological sources of ozone precursor emissions such as trees, agricultural crops, or microbial
activity in soils or water. VOC and NOX emissions can also result from geological activity, most notably
from seeps of oil or natural gas, volcanoes, and fumaroles (i.e., vapor or gas vents in a volcanic region).
Soil wind erosion is a geogenic source of PM10 and PM2 5 emissions (although in the past this process has
also been considered to be an anthropogenic fugitive dust component of PM emissions inventories). At this
time, the emission estimation methodology for wind erosion is being refined by EPA. In addition, lightning
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may also be a significant contributor to natural NOX emissions in an inventory area. Table 2d of the CERR
specifies the data elements for biogenic source reporting.
According to the CERR, a baseline biogenic emissions inventory is required to be established for each
State. Triennial updates to this baseline inventory are only required if land use characteristics used in
determining biogenic emissions have changed, or if a new method is used to determine emissions. To the
extent that the EPA develops a biogenic baseline for the specified base year inventory [e.g., using Biogenic
Emissions Inventory System-3 (BEIS-3)], it would be acceptable and practical for a State to use these EPA-
generated emission estimates as the basis for their SIP planning and modeling inventories. EPA issued a
NEI Listserve message on November 14, 2003 that details how State, local and Tribal agencies may use the
EPA prepared 2002 biogenics inventory for CERR purposes. Contact INFO CHIEF (919-541-1000) for a
copy of this listserve message. For attainment demonstration purposes, biogenic emissions are calculated
"on the fly" within the air quality model and the use of prior biogenic inventories would not be necessary.
State, local and Tribal agencies may use non-BEIS-3 estimates if they believe they have more representative
data for estimating biogenic emissions and can demonstrate better quality emissions data.
The EPA also encourages State, local and Tribal agencies to prepare an inventory of all significant
geogenic sources in the inventory area, including wind erosion.
4.1.6 Electronic Data Transfer
4.1.6.1 Protocol for Transferring Data Electronically to the EPA National
Emission Inventory (NEI)
Because the submittal of emissions data from State, local and tribal agencies represent a very large
amount of data to consider for inclusion in the NEI, the data must be provided in one of the acceptable
formats that EPA is readily able to read and process.
At present there are two acceptable formats for the State, local, and tribal agencies to use for
incorporation into the NEI - the NEI Input Format (NIF) and NEI xml schema - extensible markup language
(XML) format.
Both formats are described and located on http://www.epa.gov/ttn/chief/nif/. The format specifications
and user materials are available on this site for prosepective users to download or may be in the case of xml,
linked to and located on the National Environmental Information Exchange Network site. Information on
these sites will provide users with the format specification, its prescribed conventions of use, the file types
that may be used to prepare the formatted file, available tools for checking format errors, and electronic
protocols and instructions for transferring the data electronically to EPA.
The NIF and XML formats contain the same data element content, though packaged differently. Either
file format may be used to move the data of interest to the NEI including the data reporting required by the
CERR.
Whether a State, local, or tribal agency uses the NIF or XML format noted above, they will all move
their files to the NEI through the EPA's Central Data Exchange node on the National Environmental
Information Exchange Network (NEIEN). The NEIEN is administered in partnership with the
Environmental Council of States (ECOS) and is maintained by the EPA's Office of Environmental
Information (OEI) for all data flows in the Agency. Some State, local and Tribal agencies also operate a
node on the NEIEN, and more are expecting to do so in the future. Node-to-node, or automated machine-to-
machine transmissions over the NEIEN are planned in the future for the NEI data transfers. Node-to-node
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exchanges over the NEIEN will use XML .
CDX registration and submission procedures for State, local, and tribal agencies are located at
http://www.epa.gov/ttn/chief/nif/c dx.html. The sequence of events minimally involved in the electronic
transfer of files through CDX are summarized below.
• Data submitter registers on-line at CDX.
• CDX on-line - the data submitter completes NEI submittal form to generally describe the data, zips and
names file as prompted by CDX instruction, and sends the file.
• Submitters receive an automated message from CDX upon receipt of files at CDX and a second
automated message from CDX upon download by EIG.
• EPA downloads the files received at CDX from a secure password-protected CDX website to a secure
local network drive accessible by NEI program staff.
4.1.6.2 Direct Source Reporting
Certain point sources may already be reporting electronic emissions data directly to EPA. For example,
electricity-generating units subject to Title IV Acid Rain monitoring and reporting provisions must report
continuous emission monitoring system (CEMS) data in a specified electronic data reporting (EDR) format
to EPA. In addition, large industrial combustion sources participating in regional NOX mass emissions
trading programs (e.g., under 40 CFR Part 96) are allowed to submit data using this method. This CEMS
data may not directly fulfill reporting requirements for all pollutants that would constitute a State's ozone,
fine PM, or regional haze SIP submittal. However, EPA acknowledges this to be a viable data option where
reporting requirements overlap, and would like to encourage and facilitate the use of CEMS data by State,
local and Tribal agencies and EPA. One possible option may involve the calculation of emissions for
pollutants not reported under Part 75 or Part 96 (e.g., PM10, PM2 5) by applying emission factor ratios to the
highly temporally-allocated emission estimates available for other pollutants such as NOX and SO2.
To avoid duplication of effort, the EPA envisions that these emissions data will either be:
(1) transferred into EPA's central emissions database after submittal by the source; or (2) if a State prefers,
the data can be made available to State, local and Tribal agencies for incorporation into their emissions
inventory.
4.2 DOCUMENTATION OF THE INVENTORY
The written presentation to support an emissions inventory submittal for the ozone and PM2 5 NAAQS,
as well as the regional haze rule, should contain documentation that is sufficiently detailed for EPA to
evaluate how the emission inventory was prepared. The EPA recommends that State, local and Tribal
agencies prepare adequate documentation; the level of detail included in the documentation should be
agreed upon with the Regional Office and specified in a State's IPP. This section refers to prior guidance
issued by EPA to assist in developing appropriate documentation for emission inventories.
Written documentation of calculations, assumptions, and all other activities associated with developing
the emission estimates is a key element of the QA program. Documentation of the work that is actually
performed during inventory development includes documentation of calculations (hand calculations,
spreadsheets, and databases), documentation of the QA program implementation, and documentation of the
results (the inventory report). Examples of topics requiring good documentation in the inventory
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development process include:
• point/nonpoint source cutoffs to demonstrate that double-counting of emissions does not occur
• point source information on survey mail-out procedures, tracking and logging of returned surveys,
and verification procedures for source test data
• adjustments made to source test data to represent longer periods of time, seasonal influences, etc.
• data obtained from permit and compliance files
• adjustments made for applicable rules, including control efficiency, rule penetration, and rule
effectiveness
• information obtained on emission factors and activity data (primarily for nonpoint sources)
• data references
• adjustments made for local conditions and assumptions made to adjust for scaling up emissions to
account for nonreported sources
• VMT, traffic speeds, miles of roadway for each roadway class, hot- and cold-start percentages,
vehicle age distribution, etc., for the mobile source documentation
Chapter 2 of the EIIP's Volume VI, titled Planning and Documentation, provides valuable, detailed
guidance on documenting inventory components.
For a complete example of how an inventory should be compiled and documented, State, local and
Tribal agencies are referred to the document, Example Documentation Report for 1990Base Year Ozone
and Carbon Monoxide State Implementation Plan Emission Inventories23 available at
http://www.epa.gov/ttn/chief/eidocs/exdocument.pdf. This document provides State, local and Tribal
agencies with a list of elements deemed to be essential for documenting an emissions inventory in written
form. An outline for the organization and content of a State's inventory report is presented in Table 6.2-1.
This table references another document entitled Example Emissions Inventory Documentation for Post-1987
Ozone State Implementation Plans.24 This document also addresses inventory documentation requirements
but was not explicitly designed to address 1990 inventories. However, much of the guidance provided for
post-1987 inventories would still be applicable for inventories developed for the new ozone and PM2 5
NAAQS, and regional haze rule. In addition, although these documents focus on ozone precursor and CO
emission inventories, the principles defined in these reports also apply to PM2 5 and regional haze
inventories.
Table 4.2-1. Outline for Format/Contents for SIP Emission Inventory Reports
I. Cover and Title Page
A. Title (geographic area, type of inventories, pollutants, base year)
B. Responsible agency
C. Report date (date completed/distributed)
D. Preparer (if different from responsible agency - e.g., contractor)
II. Table of Contents
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A. Contents
B. Tables
C. Figures
III. Introduction
A. Reason for report being prepared, purpose
B. Geographic area covered, base year, type of inventory (CRIT, HAP, CRITHAP),
pollutants included (VOC, NOX, CO, SO2, PM10-PRI, PM10-FIL, PM25-PRI,
PM25-FIL, PM-CON, NH3)
C. Brief discussion of contents of report
D. Discussion of automated data systems used
E. Major problems, deficiencies, portions of inventory not included
F. List of primary guidance documents and references used (EPA guidance documents,
EIIP documents, AP-42, etc.)
G. List of contacts for each distinct portion of the inventory
IV. Summary
A. Emissions (annual and seasonal) of each pollutant by major category
B. See example tables and graphics given in Example Emissions Inventory
Documentation for Post-1987 Ozone State Implementation Plans (EPA-450/4-89-
018)
V. Documentation of Emissions Methods/Data Estimates
A. Stationary Point Source Emissions
1. discussions of procedures and methodologies
2. example surveys/questionnaires
3. list of plants by primary product and total emissions
4. point source emissions summary
B. Stationary Nonpoint Source Emissions
1. discussion of procedures and methodologies
2. list of source categories and emissions
3. calculations and discussion for each source category
4. nonpoint source emissions summary
C. Mobile Source Emissions
1. Nonroad Mobile Sources
a. same information as for stationary nonpoint sources
2. Onroad Vehicles
a. mobile model inputs and outputs
b. VMT estimates
42
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c. documentation (can put all or part in Appendices)
d. mobile source emissions summary
e. discussion of procedures and methodologies
VI. Quality Assurance/Quality Control (QA/QC)
A. QA/QC plan - discussion of QA/QC methodologies used
B. Results
C. QA procedures can also be discussed in individual source category sections
In addition to the detailed emissions data submitted in electronic form, the EPA recommends that
general summaries of the emissions inventory data be compiled and submitted by State, local and Tribal
agencies. EPA Headquarters and EPA Regional Offices will use these summaries for easy and efficient
comparison with other State, local and Tribal agencies' inventories and as a check for approximate and valid
ranges of emissions. Examples of statewide emissions summaries are presented in Tables 4.8-1 and 4.8-2.
State, local and Tribal agencies may also want to consider summarizing pollutant emissions by county.
Table 4.2-2. Statewide Ozone Precursor Emissions by Source Sector
Source Type
Point Sources
Nonpoint Sources
Onroad Mobile Sources
Nonroad Mobile Sources
Biogenic Sources
Geogenic Sources
TOTAL EMISSIONS
VOC Emissions
tons/yr
Ibs/day
CO Emissions
tons/yr
Ibs/day
NOX Emissions
tons/yr
Ibs/day
43
-------
Table 4.2-3. Statewide PM10, PM25, and Precursor Emissions by Source Sector
Source Type
Point Sources
Nonpoint Sources
Onroad Mobile Sources
Nonroad Mobile Sources
Biogenic Sources
Geogenic Sources
TOTAL EMISSIONS
PM10-PRI
Emissions
tons/yr
PM2.5-PRI
Emissions
tons/yr
voc
Emissions
tons/yr
NOX
Emissions
tons/yr
SO2
Emissions
tons/yr
NH3
Emissions
tons/yr
See section 3.2.1 for reporting of primary versus filterable and condensible emissions.
42
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SECTION 5
EMISSION INVENTORY DEVELOPMENT
5.1 AVAILABLE GUIDANCE
The EPA has developed numerous guidance documents to assist State, local and Tribal agencies in
developing emissions inventories for various pollutants. These include the EIIP guidance documents, AP-
42,10 available at http://www.epa.gov/ttn/chief/publications.htmlfffactor. and older documents such as
Procedures for the Preparation of Emission Inventories for Carbon Monoxide and Precursors of Ozone,
Volume I.11 Other guidance documents can be accessed using EPA's CHIEF web site at
http://www.epa.gov/ttn/chief/. The EIIP guidance documents are EPA's most recent emission inventory
development guidance and should be the primary source of guidance for State, local and Tribal agencies.
For PM2 5, EIG has developed a "getting started" web site. This web site, titled "PM2 5 Emission
Inventory Resource Center," is available at http://www.epa.gov/ttn/chief/eiip/pm25inventory/. State, local
and Tribal agencies should refer to the "PM2 5 Emission Inventory Resource Center" for information on the
latest guidance and tools for preparing PM25 emission inventories.
The EPA is also evaluating its current projections guidance, Procedures for Preparing Emissions
Projections,12 available at www.epa.gov/ttn/chief/publications.html, to determine how it should be
updated/revised to reflect the provisions of the new NAAQS, regional haze, and other programs. State, local
and Tribal agencies should refer to the existing projections guidance until new guidance is issued by EPA.
5.2 NEI
The EPA develops the NEI and provides it to State, local and Tribal agencies as well as to the public.
The NEI contains statewide emission estimates for all of the pollutants and pollutant precursors required by
this guidance. The NEI is comprehensive and includes emission estimates for point sources, nonpoint
sources, and mobile sources. The EPA believes that most State, local and Tribal agencies will find the NEI
to be a useful tool in preparing their SIP emission inventories specified by this guidance. If State, local and
Tribal agencies choose to use the NEI in their SIP inventory preparation, EPA would suggest the following
as a means of prioritizing their inventory efforts and resources:
• Point Sources - this should be the State, local and Tribal agencies' main point of emphasis for all
pollutants except PM2 5, since the CERR requires State-submitted data for point sources. Unlike
nonpoint and biogenic/geogenic sources, a State, local and Tribal agency may not rely on the
EPA-suppliedNEI for point sources.
• Nonpoint and Nonroad Mobile Sources - State, local and Tribal agencies should review their
nonpoint and nonroad source emission estimates in the NEI. The State, local and Tribal agencies
may want to concentrate their efforts on the most significant source categories. In general, the
greatest opportunity for improving the NEI nonpoint and nonroad source estimates is for the State,
local and Tribal agency to develop locally-specific activity data. The development of these
activity data should be a main point of emphasis for PM2 5.
• Onroad Mobile Sources - if State, local and Tribal agencies choose to use the NEI onroad
emission estimates as a starting point, improvements in the estimates can be made by providing
locally-specific inputs to the MOBILE model and more precise estimates of VMT.
43
-------
• Biogenic Sources - The NEI biogenic estimates are believed to be reliable. EPA encourages State,
local and Tribal agencies to use the EPA supplied biogenic estimates. However, if State, local and
Tribal agencies want to improve these estimates, locally-specific land use/land cover data can be
obtained.
• Geogenic Sources - The EPA has not yet included geogenic source emissions in the NEI due to the
lack of reliable data. The EPA is working on refining the emission estimation methodology to
produce more representative PM estimates for wind erosion sources. State, local and Tribal
agencies should prepare an inventory of all other significant geogenic sources in the inventory
area.
5.3 POINT SOURCES
Volume II of the EIIP guidance documents includes major chapters that address various combustion,
manufacturing, and production activities that are point sources.13 Volume n is available at
http://www.epa.gov/ttn/chief/eiip/techreport/volume02/index.html. Information in these chapters should be
used to estimate ozone and PM2 5 precursor emissions where they address the source categories of interest.
The EIIP point source chapters within Volume n are as follows:
• 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 Fugitive Air Emissions from
Equipment Leaks
• ChapterS: Preferred and Alternative Methods for Estimating Air Emissions from Wastewater
Collection and Treatment
• Chapter 6: Preferred and Alternative Methods for Estimating Air Emissions from
Semiconductor Manufacturing Facilities
• 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 Facilities
• Chapter 9: Preferred and Alternative Methods for Estimating Air Emissions from Secondary
Metal Production Facilities
• Chapter 10: Preferred and Alternative Methods for Estimating Air Emissions from Oil and Gas
Field Production and Processes
• Chapter 11: Preferred and Alternative Methods for Estimating Air Emissions from Plastic
Products Manufacturing
• Chapter 12: How to Incorporate Effects of Air Pollution Control Device Efficiencies and
Malfunctions into Emission Inventory Estimates.
44
-------
• Chapter 13: Preferred and Alternative Methods for Estimating Air Emissions from Stone Mining
and Quarrying Operations.
• Chapter 14: Uncontrolled Emission Factor Listing for Criteria Air Pollutants.
• Chapter 15: Preferred and Alternative Methods for Estimating Air Emissions from the Printing,
Packaging and Graphic Arts Industry.
' Chapter 16: Methods for Estimating Air Emissions from Chemical Manufacturing.
Each industry- or source-specific document contains a brief description; identification of emission points; an
overview of methods available for estimating emissions; example calculations for each technique presented;
a brief discussion on QA and QC; and the SCCs needed for entry of the data into a database management
system. The SCCs included in each volume apply to the process emission points, in-process fuel use,
storage tank emissions, fugitive emissions, and control device fuel (if applicable). More details on PM25
emission inventories are available at the "PM25 Emission Inventory Resource Center."
Table 5.3-1 lists potential point source categories. This table is presented as a guide to aid State, local
and Tribal agencies in focusing their point source emission inventory efforts, and is based on an analysis of
EPA's NEI database. The table shows where in EPA's database significant point source emissions occur.
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 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 NEI database for that source category. Note that local priorities for
inventory development may vary depending on the nature of sources in the area. State, local and Tribal
agencies should also be aware that some of these source categories may have both point and nonpoint source
components, and that they should be careful to avoid double-counting of emissions.
5.4 NONPOINT SOURCES
Nonpoint sources are generally described as those sources that are too small, numerous, or difficult to
be inventoried individually. Potential nonpoint sources of emissions are given in Table 5.4-1 and potential
crustal (dust) sources of PM emissions are given in Table 5.4-2. These tables are presented as guides to
assist State, local and Tribal agencies in focusing their nonpoint source emission inventory efforts. The
tables are based on an analysis of EPA's NEI database and show where in the database significant nonpoint
source emissions occur. As with Table 5.3-1, 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 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 NEI database for that source
category. Note that local priorities for inventory development may vary depending on the nature of sources
in the area. State, local and Tribal agencies should also be aware that some of these source categories may
have both point and nonpoint source components, and that they should be careful to avoid double-counting
of emissions.
45
-------
Table 5.4-1. Point Sources of Emissions
CATEGORY
NO*
CO
voc
S0?
PM10
PM?.
NH3*
FUEL COMBUSTION - ELECTRIC UTILITY
Coal
Gas
Internal Combustion
Oil
Other
H
M
M
M
L
L
L
L
L
L
L
L
L
L
/
H
M
L
H
L
H
L
L
M
L
H
M
M
M
L
L
L
L
L
/
FUEL COMBUSTION - INDUSTRIAL
Coal
Gas
Internal Combustion
Oil
Other
M
H
H
M
M
L
L
L
L
L
L
M
M
L
L
H
H
L
M
L
M
M
L
M
M
M
H
M
M
M
L
L
L
L
/
FUEL COMBUSTION - OTHER
Commercial/Institutional Coal
Commercial/Institutional Gas
Commercial/Institutional Oil
Miscellaneous Fuel Combustion (Except
Residential)
L
L
L
L
/
L
/
L
/
L
/
L
L
L
L
L
L
L
L
L
L
L
L
L
/
L
/
/
CHEMICAL & ALLIED PRODUCT MANUFACTURING
Agricultural Chemical Manufacturing
Inorganic Chemical Manufacturing
Organic Chemical Manufacturing
Paint, Varnish, Lacquer, Enamel Manufacturing
Pharmaceutical Manufacturing
Polymer and Resin Manufacturing
Other Chemical Manufacturing
L
L
L
/
/
/
L
/
L
L
/
/
/
L
L
/
M
L
L
M
M
L
M
L
/
/
/
M
L
L
L
/
/
L
L
L
L
L
/
L
L
M
M
L
/
/
/
/
/
METALS PROCESSING
Ferrous Metals Processing
Metals Processing NEC
Non-Ferrous Metals Processing
L
L
L
M
L
L
L
L
L
L
L
M
M
L
M
M
L
M
L
/
/
PETROLEUM AND RELATED INDUSTRIES
Asphalt Manufacturing
Oil & Gas Production
Petroleum Refineries and Related Industries
L
L
L
/
L
L
L
M
M
L
L
M
L
/
L
L
/
L
/
L
L
OTHER INDUSTRIAL PROCESSES
Agriculture, Food, and Kindred Products
Construction
Electronic Equipment
Machinery Products
Mineral Products
Miscellaneous Industrial Processes
/
/
/
M
L
/
/
/
L
L
M
/
L
L
L
M
L
/
/
M
L
M
/
L
L
M
L
M
/
L
L
H
/
L
/
/
/
/
46
-------
CATEGORY
Rubber and Miscellaneous Plastic Products
Textiles, Leather, and Apparel Products
Transportation Equipment
Wood, Pulp and Paper, and Publishing Products
SOLVENT UTILIZATION
Degreasing
Dry Cleaning
Graphic Arts
Nonindustrial
Solvent Utilization NEC
Surface Coating
Other Industrial
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 & Petroleum Product Storage
Petroleum & Petroleum Product Transport
Service Stations: Breathing & Emptying
Service Stations: Stage 1
Service Stations: Stage II
WASTE DISPOSAL AND RECYCLING
Incineration
Industrial Waste Water
Landfills
Open Burning
POTW
TSDF
Other
MISCELLANEOUS
Cooling Towers
Health Services
Other Combustion
Other
NOX
/
/
/
L
/
/
/
/
/
L
/
/
/
/
/
/
/
/
/
L
/
L
/
/
/
/
/
/
L
CO
/
/
/
L
/
/
/
L
/
L
/
/
L
L
/
/
/
/
/
L
/
/
/
/
/
/
/
/
voc
M
L
L
M
L
L
M
/
/
H
L
/
/
L
/
/
L
L
M
L
/
L
L
L
L
L
/
L
/
L
/
/
/
/
S02
/
/
M
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
L
/
/
/
/
/
/
/
PM10
L
L
/
M
/
/
/
/
L
/
M
L
/
/
/
L
/
L
/
L
/
L
/
/
/
/
L
/
/
/
PM25
L
L
/
H
/
/
/
M
/
/
/
/
L
/
L
/
L
/
L
/
/
/
/
L
/
/
L
NH3*
/
/
/
L
/
/
/
/
/
L
/
/
/
/
/
L
/
/
/
/
/
/
/
/
/
/
/
/
/
47
-------
CATEGORY
NO, CO VOC SO2 PM10 PM25 NH3'
* The emissions from all NH3 source categories need to be better characterized because of their role in the
formation of secondary particles.
Note: The H (high), M (medium), and L (low) designations indicate the level of significance of a source
category's annual emissions to the overall annual emissions of that pollutant (i.e., emissions from all
sectors).
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 1999 NEI Version 2.0.
Table 5.4-2. Nonpoint Sources of Emissions
CATEGORY
NOX
CO
VOC
S02
PM10
PM25
NH3*
FUEL COMBUSTION - ELECTRIC UTILITY
Gas
/
/
/
/
/
/
FUEL COMBUSTION - INDUSTRIAL
Coal
Gas
Internal Combustion
Oil
Other
M
M
L
L
L
L
L
/
L
L
L
L
/
L
L
M
L
/
H
L
M
L
/
L
L
L
M
/
L
L
/
L
L
FUEL COMBUSTION - OTHER
Commercial/Institutional Coal
Commercial/Institutional Gas
Commercial/Institutional Oil
Miscellaneous Fuel Combustion (Except
Residential)
Residential Wood
Residential Other
L
M
L
L
L
H
/
L
/
/
M
L
/
L
L
/
H
L
L
L
M
/
L
M
L
L
L
L
H
M
L
M
L
L
H
M
/
/
L
L
CHEMICAL AND ALLIED PRODUCT MANUFACTURING
Inorganic Chemical Manufacturing
Organic Chemical Manufacturing
Pharmaceutical Manufacturing
Polymer & Resin Manufacturing
/
/
L
L
M
/
/
METALS PROCESSING
Ferrous Metals Processing
Metals Processing NEC
Non-Ferrous Metals Processing
/
/
/
/
/
/
/
/
/
/
/
PETROLEUM & RELATED INDUSTRIES
Asphalt Manufacturing
Oil and Gas Production
/
L
/
/
L
M
/
/
/
L
/
L
48
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Table 5.4-2 (continued)
CATEGORY
Petroleum Refineries and Related Industries
OTHER INDUSTRIAL PROCESSES
Agriculture, Food, and Kindred Products
Machinery Products
Mineral Products
Miscellaneous Industrial Processes
Rubber and Miscellaneous Plastic Products
Wood, Pulp and Paper, and Publishing Products
SOLVENT UTILIZATION
Degreasing
Dry Cleaning
Graphic Arts
Nonindustrial
Other Industrial
Solvent Utilization NEC
Surface Coating
STORAGE AND TRANSPORT
Bulk Materials Storage
Bulk Terminals & Plants
Organic Chemical Storage
Organic Chemical Transport
Petroleum and Petroleum Product Storage
Petroleum and Petroleum Product Transport
Service Stations: Breathing & Emptying
Service Stations: Stage 1
Service Stations: Stage II
WASTE DISPOSAL AND RECYCLING
Incineration
Industrial Waste Water
Landfills
Open Burning
POTW
TSDF
Other
MISCELLANEOUS
Agriculture and Forestry
Catastrophic/Accidental Releases
Health Services
Other Combustion
Other
NO,
L
/
/
/
/
/
/
/
/
/
/
/
/
L
/
L
/
/
M
/
CO
/
/
/
/
/
/
/
/
/
/
/
L
/
M
/
/
H
/
voc
M
M
/
/
L
L
/
H
M
M
H
M
L
H
/
M
L
L
L
M
L
M
H
L
L
L
H
M
L
L
L
L
/
H
L
S02
/
/
/
/
/
/
/
/
/
L
/
L
/
L
PM10
M
L
L
/
L
/
L
/
H
/
H
H
PM25
L
L
L
/
L
/
L
/
H
/
H
H
NH3*
L
/
/
M
H
L
49
-------
CATEGORY
NO, CO VOC SO2 PM10 PM25 NH3'
* The emissions from all NH3 source categories need to be better characterized because of their role in the
formation of secondary particles.
Note: The H (high), M (medium), and L (low) designations indicate the level of significance of a source
category's annual emissions to the overall annual emissions of that pollutant (i.e., emissions from all
sectors).
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 1999 NEI Version 2.0.
Table 5.4-3. Crustal Sources of Emissions
CATEGORY
MISCELLANEOUS
Agricultural Crops (Tillage)
Construction
Paved Roads
Un paved Roads
Other Fugitive Dust (e.g., Mining
and Quarrying)
NATURAL SOURCES
Geogenic, Wind Erosion
NOX
CO
VOC
S02
PM10
M
H
H
H
M
NA
PM25
M
H
H
H
M
NA
NH3
Note: The impact of crustal sources on PM2 5 ambient concentrations is much lower than would be
suggested by their estimated emissions (relative to other directly emitted PM2 5).
The H (high) and M (medium) designations indicate the level of significance of a source category's
emissions to the overall emissions of that pollutant.
Geogenic wind erosion estimates, although expected to be significant in certain areas, are not
currently reported in EPA's NEI Version 2.0 due to the uncertainty associated with emission
estimation methods for this category.
The EIIP Area Source Committee has issued preferred and alternate emission estimation methods
documents under EIIP Volume III (available at
http://www.epa.gov/ttn/chief/eiip/techreport/volume03/index.html) for the following categories:u
• Chapter 2: Residential Wood Combustion
• Chapter 3 Architectural Surface Coating
• Chapter 4: Dry Cleaning
• ChapterS: Consumer and Commercial Solvent Use
50
-------
• Chapter 6: Solvent Cleaning
• Chapter 7: Graphic Arts
• Chapter 8: Industrial Surface Coating
• Chapter 9: Pesticides - Agricultural and Nonagricultural
• Chapter 11: Gasoline Marketing
• Chapter 12: Marine Vessel Loading, Ballasting, and Transfer
• Chapter 13: Autobody Refmishing
Chapter 14: Traffic Paints
• Chapter 15: Municipal Landfills
• Chapter 16: Open Burning
• Chapter 17: Asphalt Paving
• Chapter 18: Structure Fires
• Chapter 24: Conducting Surveys for Area Source Inventories
The EIIP Volume HI, Chapter 1 document lists potential activity data sources by category. Procedures
for the Preparation of Emission Inventories for Carbon Monoxide and Precursors of Ozone, Volume I also
gives detailed guidance for estimating ozone precursor emissions from nonpoint sources.11 Agencies should
review the EH? documents carefully for information on the types and sources of data needed to develop
emissions estimates for each source category.
5.5 MOBILE SOURCES
Mobile sources consist of both highway vehicles (cars and trucks) and nonroad mobile sources (e.g.,
airplanes, motorboats, farm equipment, etc.). Table 5.5-1 lists mobile source categories that EPA believes
are significant sources of emissions. This table can be used as a guide to assist State, local and Tribal
agencies in focusing their mobile source emission inventory efforts, and is based on an analysis of EPA's
NEI database. The H (high), M (medium), and L (low) designations indicate the level of significance of a
source category's annual emissions to the overall annual 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 NEI database for that source category.
Note that local priorities for inventory development may vary depending on the nature of sources in the area.
Table 5.5-1. Mobile Sources of Emissions
CATEGORY
NOX
CO
voc
SO2
PM10
PM25
NH3*
HIGHWAY VEHICLES
Diesels
Heavy-Duty Gas Vehicles
Light-Duty Gas Trucks
Light-Duty Gas Vehicles & Motorcycles
H
H
H
H
M
M
H
H
M
H
H
H
M
L
L
M
M
L
M
M
H
L
M
M
L
L
M
M
NONROAD VEHICLES AND ENGINES
Aircraft
Marine Vessels
Nonroad Diesel
Nonroad Gasoline
Railroads
Other
L
H
H
M
H
M
L
L
M
H
L
M
L
L
M
H
L
/
L
M
M
L
L
/
L
M
H
M
L
L
L
M
H
M
M
L
L
/
L
51
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CATEGORY
NOX
CO
VOC
S02
PM10
PM25
NH3*
* The emissions from all NH3 source categories need to be better characterized because of their role in the
formation of secondary particles.
Note: The H (high), M (medium), and L (low) designations indicate the level of significance of a source
category's emissions to the overall annual emissions of that pollutant (i.e., emissions from all
sectors).
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 1999 NEI Version 2.0.
The following sections discuss the models and data sources for onroad mobile sources and nonroad
mobile sources, respectively.
5.5.1 Onroad Mobile Sources
Ozone precursor emissions for onroad sources are estimated using emission factors generated by
emission factor models combined with estimates of activity, generally in terms of VMT. The currently
accepted onroad emission factor model is the MOBILE6.2 model developed by EPA's Office of
Transportation and Air Quality (OTAQ). MOBILE6.2 was released in February 2004 and can generate
onroad emission factors of VOC, NOX, CO, primary PM10 and PM2 5, SO2, and NH3 for each of the vehicle
categories shown in Table 5.5-2. Emissions may be aggregated to or calculated at the SCC level of detail
shown in Table 5.5-2. The use of VMT activity data and these onroad mobile emission factor models are
discussed further below.
VMT Activity Data
Each State's highway or transportation agency provides annual data to the Federal Highway
Administration's (FHWA) Highway Performance Monitoring System (HPMS). The FHWA uses the data
provided by the States to report the condition of the nations' highways to Congress. The HPMS compiles
VMT at the State level for rural, urban, and individual urbanized areas by 12 different road types, and six
distinct vehicle types. These six HPMS vehicle types are shown in the column to the far right in Table 5.5-
2, mapped to the appropriate MOBILE6.2 vehicle type. By normalizing the VMT fractions for each
MOBILE6.2 vehicle type within a specific HPMS vehicle type, VMT data at the HPMS vehicle type level
can be converted to VMT data for each of the MOBILE6 vehicle types. The report, Use of Locality Specific
Transportation Data for the Development of Mobile Source Emission Inventories15 available at
http://www.epa.gov/ttn/chief/eiip/techreport/volume04/index.html contains sections addressing
improvements to travel demand model (TDM) outputs. In 1993, FHWA issued a letter indicating that all
urban areas greater than 50,000 population should have individual HPMS sample panels representative of
travel within those areas.
The EPA guidance, Procedures for Emission Inventory Preparation - Volume IV: Mobile Sources,16
available at http://www.epa. gov/otaq/invntory/r92009.pdf provides a very detailed discussion of HPMS and
TDMs. Pages 62 to 94 of this document discuss how to use HPMS data and the more limited cases when
TDMs may be used. In general, HPMS is the preferred method for estimating historical VMT and TDMs
are the preferred method for allocating VMT to the county level and road classes and for calculating growth
52
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factors for future years. The guiding principal of this policy is that the State should provide the same
estimate of travel to the EPA as it uses internally and provides to the FHWA.
The approval of the use of any alternative to HPMS will be made by the EPA Regional Office. State,
local and Tribal agencies are encouraged to identify in their IPP their proposed method for determining
historical VMT, for allocating VMT to the county level and road classes, and for calculating growth factors
for future years.
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Table 5.5-2. MOBILE6.2 Vehicle Classes
MOBILES
LDGV
LDGT1
LDGT2
LDGT3
LDGT4
HDGV2b
HDGV3
HDGV4
HDGV5
HDGV6
HDGV7
HDGVSa
HDGVSb
HDGB
MC
LDDV
LDDT12
LDDT34
HDDV2b
HDDV3
HDDV4
HDDV5
HDDV6
.2 Vehicle Class and Description
Light-duty gasoline vehicles
(passenger cars)
Light-duty gasoline trucks 1
Light-duty gasoline trucks 2
Light-duty gasoline trucks 3
Light-duty gasoline trucks 4
Class 2b heavy-duty gasoline vehicles
Class 3 heavy-duty gasoline vehicles
Class 4 heavy-duty gasoline vehicles
Class 5 heavy-duty gasoline vehicles
Class 6 heavy-duty gasoline vehicles
Class 7 heavy-duty gasoline vehicles
Class 8a heavy-duty gasoline vehicles
Class 8b heavy-duty gasoline vehicles
Gasoline buses (school, transit, and
urban)
Motorcycles
Light-duty diesel vehicles (passenger
cars)
Light-duty diesel trucks 1 and 2
Light-duty diesel trucks 3 and 4
Class 2B heavy-duty diesel vehicles
Class 3 heavy-duty diesel vehicles
Class 4 heavy-duty diesel vehicles
Class 5 heavy-duty diesel vehicles
(single-unit, 2-axle, 6-tire trucks)
Class 6 heavy-duty diesel vehicles
7-Digit Source
Classification
Code (SCC)
2201001
2201020
2201020
2201040
2201040
2201070
2201070
2201070
2201070
2201070
2201070
2201070
2201070
2201070
2201080
2230001
2230060
2230060
2230071
2230072
2230072
2230072
2230073
Gross
Vehicle
Weight
Rating
(Ibs)
< 6,000,
<3,750lb
LVW
<6,000,
3,751 - 5,750 Ib
ALVW
6,001 -8,500,
< 5,750 Ib
ALVW
6,001-8,500
>5,750lb
ALVW
8,501 - 10,000
10,001 -
14,000
14,001 - 16,
000
16, 001 -
19,500
19,501 -26,
000
26,001 -
33,000
33,001 -
60,000
> 60,000
< 6,000
6,001 -8,500
8,501-10,000
10,001 -
14,000
14,001 -16,
000
16, 001 -
19,500
19,501 -26,
HPMS
Vehicle
Category
cars
O2X4T
O2X4T
O2X4T
O2X4T
O2X4T
SU2X6T
SU2X6T
SU2X6T
SU2X6T
SU2X6T
COMB
COMB
buses
MC
cars
O2X4T
O2X4T
O2X4T
SU2X6T
SU2X6T
SU2X6T
SU2X6T
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HDDV7
HDDVSa
HDDVSb
HDDBT
HDDBS
Class 7 heavy-duty diesel vehicles
Class 8a heavy-duty diesel vehicles
Class 8b heavy-duty diesel vehicles
Diesel transit and urban buses
Diesel school buses
2230073
2230074
2230074
2230075
2230075
26,001 -
33,000
33,001 -
60,000
> 60,000
SU2X6T
COMB
COMB
buses
buses
LVW = loaded vehicle weight, ALVW = average loaded vehicle weight
O2X4T = other 2-axle, 4-tire vehicles, SU2X6T = single-unit, 2 axle, 6-tire trucks
COMB = combination trucks, MC = motorcycles
Onroad Mobile Models
Onroad mobile source VOC, NOX, CO, SO2, primary PM10 and PM2 5, and NH3 emission factors are
calculated using an emission factor model. MOBILE6.2 is EPA's current onroad emission factor model.
MOBILE6.2 generates exhaust and evaporative emission factors in grams per mile. Emission factors for
brake wear and tire wear are also generated for PM. These factors must then be multiplied by the VMT
activity estimates, discussed above, to estimate emissions. The MOBILE6.2 model replaces the MOBILES
model for VOC, CO, and NOX and PARTS for PM and SO2. Although PARTS also included the ability to
estimate emission factors from fugitive dust from paved and unpaved roads, MOBILE6.2 does not include
the estimation of these emission factors. EIG has revised the AP-42 paved road and unpaved road emission
factors to enable users to estimate emission factors for fugitive dust from paved and unpaved roads. The
EPA has developed a new mobile modeling tool. The National Inventory Emissions Model (NMIM) is
essentially a graphical user interface that uses MOBILE6.2, NONROAD2002, and a database which
contains modeling information for each county in the US to generate these inventories. NMIM will be
released in late summer or fall of 2005. In addition, EPA is developing a new emissions model. The Multi-
Scale Motor Vehicle and Equipment Emission System (MOVES) is under development and is intended to
include and improve upon the capability of MOBILE6.2 and will eventually replace the MOBILE6.2 model,
as well as EPA's current NONROAD emission model, with a single comprehensive mobile source modeling
system. The onroad portion of this model is expected to be functional for criteria pollutants by 2007. The
latest information on the development of this model can be found at http://www.epa.gov/otaq/ngm.htm.
California has developed its own onroad emission factor model known as EMFAC. This model accounts for
the California-specific emission standards.
The MOBILE6.2 model, user's guides, and associated documentation are all available at EPA's OTAQ
web page at: http://www.epa.gov/otaq/m6.htm. A technical guidance document concerning the use of
MOBILE6 for preparing emission inventories for SIPs and transportation conformity determinations is also
available at that web site. In addition, this site contains a policy guidance document that details the schedule
for using MOBILE6.2 in SIPs and transportation conformity determinations as well as the required inputs.
State, local and Tribal agencies should plan for compiling an onroad inventory using MOBILE6.2 by
developing the best possible set of local inputs for variables such as registration distribution, I/M program
inputs, defining the geographic and temporal applicability of other control programs (e.g., in which counties
and what months is oxygenated fuel used), mileage accumulation rates, and determining what temperature
data will be used for each of the different types of inventories. State, local and Tribal agencies should also
have methods in place for determining fuel characteristics throughout the State and according to season,
including fuel Reid vapor pressure (RVP), sulfur level, oxygen content, and the makeup of reformulated
gasoline. For all types of onroad vehicle emission modeling (e.g., ozone modeling, 3-year cycle inventories,
transportation conformity), having an accurate, local registration distribution is important to determining
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accurate emission inventories. Because wide differences between actual model year fleet distributions and
default distributions in the MOBILE6.2 model have been observed, State, local and Tribal agencies are
encouraged to use county-specific motor vehicle model year distributions obtained from their State motor
vehicles office. For the 3-year cycle and modeling inventories, having accurate representations of control
programs in place during the modeled time periods is crucial, particularly for I/M program modeling. For
example, if a set of phase-in cutpoints are being used in an I/M program in 2002, it is important to model
that set of cutpoints rather than the final set of emission cutpoints. On the other hand, for attainment
demonstration or projection inventories, where allowable emissions are calculated, the final planned I/M
program may be modeled. Modeling accurate speeds by roadway type, while important for all inventory
types, is particularly important in transportation conformity modeling. In this case, it is necessary to capture
the changes in average speeds by roadway type or roadway link due to the presence or absence of particular
transportation-related programs.
The temperature inputs used in the MOBILE6.2 model will depend upon the purpose of the inventory
as well as the time period covered by the inventory. For annual inventories, EPA's general practice has
been to develop monthly emissions based on average monthly maximum and minimum daily temperatures.
The monthly emissions are then summed to obtain annual emissions. In the other extreme, when developing
onroad inputs for emission modeling, actual hourly temperatures are generally used to model the particular
days of interest. In past practice, ozone SIPs have typically required the use of ozone season day
temperatures, based on the temperatures that occurred during an area's highest ozone recordings over a
specified 3-year period. This method can be difficult and with new designations, monitored data might be
scarce. EPA will accept the use of actual average day temperature for the month of July. If NMIM is
employed, it requires hourly average temperatures. Temperature and humidity data can be obtained from
the National Climatic Data Center. Temperature inputs used in developing conformity budgets should be
consistent with the temperature inputs used in an area's SIP modeling.
The MOBILE6.2 technical guidance document provides recommendations for determining appropriate
values for MOBILE6.2 model inputs and the conversion of MOBILES inputs to MOBILE6 inputs. For
many of the input options in MOBILE6.2, the EPA encourages the use of non-default inputs by users of the
model, but requests that State, local and Tribal agencies discuss the selection of any non-default values in
documentation submitted with the onroad mobile source emission inventory.
Reporting of Emissions
The CERR requires States to report onroad emissions by SCC. Valid SCC codes can be found at
http://www.epa.gov/ttn/chief/codes/index.htmltfscc. This listing provides a variety of reporting levels for
the onroad sector. EPA has not developed SCC codes for all of the 28 vehicle types included in MOBILE6
because of data storage limitations. While emissions may be calculated at that level, when emissions are
reported to EPA for inclusion in the NEI, emission modeling, or other purposes, the preferred level of detail
is at either the 8-vehicle type (LDGV, LDGT1, LDGT2, HDGV, LDDV, LDDT, HDDV, and MC) or 12-
vehicle type level of detail. The 12-vehicle type level of detail is the 8-vehicle type level of detail, with the
HDDV category subdivided into 5 weight categories (Class 2B HDDVs; Class 3, 4, and 5 HDDVs; Class 6
and 7 HDDVs; Class 8A and 8B HDDVs; and diesel buses). These SCC codes are shown in Table 5.5-2,
with the corresponding MOBILE6 vehicle types included in each of the 12 vehicle categories. Following
the first 7 digits of the vehicle type portion of the SCC code are three additional digits. The digits in the
eighth and ninth positions of the SCC codes represent the 12 HPMS facility types. These codes are shown
in Table 5.5-3, along with the EPA-recommended MOBILE6.2 facility type corresponding to each of the
HPMS facility types. The code in the tenth digit of the SCC can be used to indicate whether the emissions
represent exhaust emissions (X), evaporative emissions (V), brake wear emissions (B), or tire wear
emissions (T). A "0" is used in the tenth digit of the SCC if this breakdown of the emissions is not
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available.
Table 5.5-3. HPMS Facility Types
Facility Type Source
Classification Code Recommended MOBILE6.2
HPMS Facility Type (SCC) Facility Type
Rural Interstate
Rural Other Principal Arterial
Rural Minor Arterial
Rural Major Collector
Rural Minor Collector
Rural Local
Urban Interstate
Urban Other Freeways and Expressways
Urban Other Principal Arterial
Urban Minor Arterial
Urban Collector
Urban Local
11
13
15
17
19
21
23
25
27
29
31
33
Freeway
Arterial
Arterial
Arterial
Arterial
Arterial
Freeway
Freeway
Arterial
Arterial
Arterial
Local
5.5.2 Nonroad Mobile Sources
The EPA's OTAQ is developing a computer model, NONROAD, to directly estimate pollutant
emissions for the following nonroad equipment categories:
• Lawn and Garden
- residential
- commercial
• Construction and Mining
• Agricultural
• Industrial
• Airport Service
• Recreational Vehicles
Logging
• Recreational Marine
• Light Commercial
• Railway Maintenance
Within these general categories are more specific types of equipment (e.g., 2-wheel tractors, balers, and
combines are examples of 10-digit SCCs within the broader 7-digit SCC defining agricultural equipment).
Because of the variations in hours of use, horsepower, and load factors corresponding to engines in various
applications, these distinctions are necessary. These applications can be further classified according to fuel
and engine type [diesel, gasoline 2-stroke, gasoline 4-stroke, compressed natural gas (CNG), and liquid
petroleum gas (LPG)].
The NONROAD model estimates emissions for six exhaust pollutants: HC, NOX, CO, PM, SO2, and
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carbon dioxide (CO2). Hydrocarbons (HC) can be reported as total hydrocarbons (THC), TOG, nonmethane
organic gases (NMOG), NMHC, or VOC. Particulate matter can be reported as primary emissions of total
PM, PM10 (which is equivalent to total PM), or PM2 5. The model also estimates non-exhaust HC emissions,
including crankcase, diurnal, and refueling emissions. The model allows the user to report total HC
emissions, which account for both exhaust and relevant non-exhaust components (depending on the engine
type and pollutant). At the present time, the NONROAD model does not generate NH3 emissions.
Although nonroad engines are not a significant source of NH3, emissions for NH3 can be estimated by
multiplying SCC-level fuel consumption, in gallons (available from the NONROAD model), by gram/gallon
NH3 emission factors developed by OTAQ.
NONROAD allows the calculation of pollutant emissions at the national, State, and county level. The
model can also estimate sub-county (i.e., nonattainment area) emissions if the necessary inputs to perform
this calculation are supplied by the user. By using estimates of annual activity for each equipment type,
annual emissions inventories can be calculated. Additional inventories can be calculated on a seasonal (i.e.,
summer, fall, winter, spring), monthly, or daily (i.e., week or weekend day) basis by allocating annual
activity to these smaller time periods. Past year, present year, and future year inventories (up to the year
2050) can be generated with this model.
The NONROAD model estimates emissions for each specific type of nonroad equipment by
multiplying the following input variables:
• Equipment population for a specified year, distributed by age, horsepower, fuel type, and
application;
• Average load factor expressed as average fraction of available power;
• Activity in hours of use per year; and
• Emission factor, accounting for engine deterioration and any applicable new standards.
The emissions are then temporally and geographically distributed using appropriate allocation factors.
State, local and Tribal agencies have the option of replacing default model values with more
representative data if available. If a State, local and Tribal agency makes changes to default model values
such as local equipment populations, geographic allocations, and local growth rates, the agency should
submit the input files to EPA, as well as a description of why the defaults were changed. The EIIP has
published a report entitled, Guidance for Estimating Lawn and Garden Equipment Activity Levels17
available at http://www.epa.gov/ttn/chief/eiip/techreport/volume04/index.html, that discusses methods for
improving estimates of local lawn and garden equipment populations according to commercial and
residential use.
If NMIM is used, it will use the same temperature and fuel information for onroad MOBILE and
nonroad NONROAD calculations. NMIM runs the NONROAD model on a monthly basis.
OTAQ has posted technical reports on their web site that describe the various default input variables.
Copies of these reports, as well as the most recent version of the NONROAD model
(including user's guide) can be downloaded from the web site: http://www.epa.gov/otaq/
nonrdmdl.htm#model. In addition, a CD-ROM copy of the model can be obtained from OTAQ by request.
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Commercial Marine Vessels, Aircraft, and Locomotives
The NONROAD model does not provide State, local and Tribal agencies with a tool for estimating
emissions for commercial marine vessels, aircraft, and locomotives. Guidance on emission estimation
methodologies for these categories was originally published by EPA in the report, Procedures for Emission
Inventory Preparation, Volume IV: Mobile Sources.u Following is a discussion on the status of updated
guidance for commercial marine vessels, aircraft, and locomotive categories.
OTAQ originally intended to incorporate a commercial marine module into the NONROAD model.
However, due to unexpected complications in developing input data and the requisite computer code, OTAQ
discontinued work on the electronic commercial marine module for the NONROAD model, and focused
instead on written guidance. In 1999, EPA sponsored two studies entitled, "Commercial Marine Activity for
Great Lake and Inland River Ports in the United States,"19 and "Commercial Marine Activity for Deep Sea
Ports in the United States."20 These studies provide activity profiles for approximately 150 ocean, lake, and
river ports, and present a method for an inventory preparer to allocate time-in-mode activity data from one
of four typical ports to another port that has similar characteristics. Activity profiles for a typical port
include: 1) number of vessels in each category; 2) vessel characterization, including propulsion size
(horsepower), capacity tonnage, and engine age; 3) number of hours at each time-in-mode associated with
cruising, reduced speed, maneuvering, and hotelling. It should be noted that this guidance only addresses
methods to estimate commercial marine activity. EPA's current marine inventory guidance document18 uses
modeling techniques based on fuel consumption that were common at that time. Since then, new marine
inventory techniques have been developed as part of the rulemaking process for emission standards for
commercial marine diesel engines. These techniques are more similar to the techniques used for mobile
sources generally, and rely on emission factors, population estimates, and usage characteristics. These
techniques are currently being used to update the marine inventories and to develop marine components for
the MOVES model. This new work will provide the foundation for a new marine inventory guidance
document, including more research into emission factors, populations, and operating characteristics. Until
that time, States and other stakeholders are encouraged to refer to the inventories prepared for the
commercial marine diesel engine standards for use in developing their own inventories. The Regulatory
Support Documents for those rules contain the inventory estimates and a description of how those estimates
were produced.
Emissions for commercial aircraft engines can be estimated using the Federal Aviation
Administration's (FAA) Emission Dispersion Modeling System (EDMS). The EDMS model requires
detailed inputs on aircraft operation by aircraft and engine type. Aircraft activity data in the form of landing
and take-offs (LTOs) can also be obtained from the FAA, if not available directly from airports (e.g.,
through surveys). Users should be aware that emission factor data for all aircraft types/engine models may
not be available in EDMS, so default engine assignments may need to be made. In addition, the current
version of EDMS does not contain PM emission factors. EPA OTAQ is working with the FAA to add this
capability. The EDMS is available at the following web site:
http://www.aee.faa.gov/emissions/EDMS/edmshome.htm. For air taxi, general aviation, and military
aircraft, emission factors are available from EPA's 1989 mobile source emissions preparation guidance.
These represent fleet-average emission factors and should be applied to activity data, or LTOs, for these
aircraft types.
For the locomotive category, inventory preparers should account for Class I and Class II/III rail
operations, as well as passenger and commuter line activity in their area. The activity data (i.e., fuel
consumption) may be obtained by directly contacting individual railroads in the inventory area. Switch yard
operations should also be identified. Both line haul and yard emissions can be estimated using EPA
recommended emission factors, available at http://www.epa.gov/otaq/locomotv.htm. The EIIP also has
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plans to issue further guidance for preparing locomotive emission estimates, expected in fall 2004.
Those seeking additional information related to emission estimation methods and emission factors for
these nonroad categories should direct inquiries to OTAQ's Assessment and Standard Division Information
Line at (734) 214-4636; e-mail: asdinfo@epa.gov.
5.6 BIOGENIC AND GEOGENIC SOURCES
Biogenic and geogenic sources contribute to pollutant emissions as indicated in Table 5.6-1.
Table 5.6-1. Natural Source Categories and Pollutants Emitted
Source
Biogenic
- Vegetation
- Soil Microbial Activity
Geogenic
- Oil and Gas Seeps
- Wind Erosion
Other Natural
- Lightning
- Stratospheric Injection*
- Oceans*
Pollutant
VOC
/
/
NOX
/
/
/
/
PM10
/
PM25
/
* NOX emissions from each of these sources contribute 2 percent or less of the
total global NOX budget, and will not be discussed further.
5.6.1 Biogenic Sources
Biogenic sources are a subset of natural emissions sources that may contribute significantly to an
emissions inventory. Vegetation (i.e., forests and agriculture) is the predominant biogenic source of VOC
and is typically the only source that is included in a biogenic VOC emissions inventory. Microbial activity
in the soil contributes to natural biogenic NOX emissions.
State, local and Tribal agencies are referred to the EIIP document, Volume V, Biogenic Sources
Preferred Methods,21 for a detailed description of some of the biogenic source emissions that should be
considered when preparing an emissions inventory. One of the major constituents of biogenic emissions,
isoprene, is highly photoreactive. Because of this characteristic, inclusion of biogenic emissions is deemed
essential for photochemical air quality modeling for ozone. In addition, some biogenic VOC may ultimately
contribute to secondary particle formation, and would therefore be important with respect to a fine PM or
regional haze inventory. Computer models available for State, local and Tribal agencies to estimate
speciated biogenic emissions include the following:
BEIS2.3 [A Personal Computer (PC) version of BEIS];
BEIS3.12
• Global Biosphere Emissions and Interactions System (GLOBEIS3.1); and
• Biogenic Model for Emissions 3 (BIOME3).
Other alternative (but less preferable) methods for estimating biogenic emissions are also discussed in
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Volume V of the EH? document. In addition, the California Air Resources Board (CARB) has developed
the Biogenic Emissions Inventory Geographical Information System (BEIGIS), a biogenic emissions model
tailored to conditions and available data for California.
The BEIS2.3 model was developed by scientists at EPA and the National Center for Atmospheric
Research (NCAR) with NCAR contributing emission factor algorithms and EPA developing national
landuse/landcover (LULC) data (Biogenic Emissions Landcover Databases [BELD]). BEIS2.3 is a stand-
alone processor that produces biogenic estimates for use with several existing air quality models. The
BEIS2.3 model also estimates biogenic emissions from soil, which may be a significant source of NOX
emissions in rural areas. BEIS2.3 output is typically used only for inventory reporting purposes.
BEIS3.12 is designed to create a SMOKE emissions output file, suitable for input to models such as
Models-3/Community Multiscale Air Quality (CMAQ); it is not a PC version.
GLOBEIS and BIO ME are biogenic emission models developed by the Texas Commission on
Environmental Quality (TCEQ)TNCAR and the Lake Michigan Air Directors Consortium (LADCO),
respectively, for use in combination with photochemical modeling systems such as Comprehensive Air
Quality Model with extensions (CAMx) and CMAQ. Both GLOBEIS3.1 and BIOME3 algorithms reflect
improvements to the biogenic emission algorithms incorporated into BEIS2. The GLOBEIS model is a
desk-top tool that is coded in MS Access, has a Graphical User Interface (GUI), and has extensive built-in
QA and reporting functions. The GLOBEIS model is publicly available from: www.globeis.com. BIOME
is coded in SAS, and allows the user to display maps of gridded emissions by pollutant. Additional
information on BIOME can be found at: http://64.27.125.175/tech/emis/biogenics/biome3/biome3.htm.
State, local and Tribal agencies are encouraged to use EPA-generated BEIS emission estimates as the
basis for their SIP planning inventories. State, local and Tribal agencies should note that biogenic emissions
are required in a projected year inventory. However, unless there are anticipated changes in land use or
vegetation patterns for the modeling area, it is appropriate to assume that biogenic emissions will remain the
same between the base year and projected year. Readers can track the status of EPA's biogenic emissions
modeling efforts at: http://www.epa.gov/asmdnerl/biogen.html.
5.6.2 Geogenic and Other Natural Sources
Geogenic emissions are primarily the result of oil or natural gas seeps and soil wind erosion. In
addition, lightning may also be a significant contributor to natural NOX emissions in an inventory area.
Volcanoes and fumaroles (i.e., vapor or gas vents in a volcanic region) can be additional sources of geogenic
emissions.
As a source of ozone precursor emissions, geogenic sources are less significant than biogenic sources.
However, geogenic wind erosion may contribute substantially to PM emissions in an area. At this time, the
emission estimation methodology for wind erosion is being refined by EPA to produce more representative
PM estimates for this category.
State, local and Tribal agencies should also prepare an inventory of all other significant geogenic
sources in the inventory area. Methods for estimating VOC emissions from oil and gas seeps, as well as
NOX emissions from lightning, are described in the EOF document, Volume V, Biogenic Sources Preferred
Methods available at http://www.epa.gov/ttn/chief/eiip/techreport/volume05/index.html. For oil and gas
seeps, the preferred method is to develop a local emission factor based on the study of oil or gas seeps in the
inventory area. The document also describes an alternative method developed by CARB22 (available at
http://www.arb.ca.gov/emisinv/areasrc/fullpdf/full9-2.pdf) that includes simplifying assumptions for oil or
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gas seeps whose specific flow rates and volatile fractions have not been studied and are not known.
Lightning produces NO, which is oxidized to NO2 in the presence of ozone or in a photochemically
reactive atmosphere. Because lightning is not a direct source of NO2, accounting for this source category is
more important for air quality modeling purposes than for SIP inventory purposes. NO emissions from
lightning can be estimated by collecting activity data on the cloud-to-ground lightning flashes, assuming a
frequency of intra-cloud flashes based on the value for CG lightning flashes, and applying appropriate
emission factors (in molecules NO per flash) to these activity levels.
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SECTION 6.0
QUALITY ASSURANCE
As part of the 8-hour ozone NAAQS, PM2 5 NAAQS, and regional haze rule, State, local and Tribal
agencies are encouraged to perform QA checks and procedures on their inventories. State, local and Tribal
agencies can develop and select the QA procedures they will perform, and should include the details of their
QA program (including specific procedures) in their IPPs.
The purpose of QA is to ensure the development of a complete, accurate, and consistent emission
inventory. A well-developed and well-implemented QA program fosters confidence in the inventory and in
any resulting regulatory and/or control program.
The overall QA program consists of two components: QC and external QA activities. Quality control
is a system of routine technical activities designed to measure and control the quality of the inventory as it is
being developed. The QC system provides routine and consistent checks and documentation points in the
inventory development process to verify data integrity, correctness, and completeness; identifies and
reduces errors and omissions; maximizes consistency within the inventory preparation and documentation
process; and facilitates internal and external inventory review processes. Quality control activities include
technical reviews, accuracy checks, and the use of approved, standardized procedures for emission
calculations, and should be included in inventory development planning, data collection and analysis,
emission calculations, and reporting.
An effective QA program includes planning, numerous QC checks during the inventory development
process, and QA audits at strategic points in the process. The EPA has developed several guidance
documents designed to assist State, local and Tribal agencies in designing and implementing their QA
programs. The EIIP Volume VI, available at
http://www.epa.gov/ttn/chief/eiip/techreport/volume06/index.html, addresses QA issues, including the
following:5
Chapter 1: Introduction - The Value ofQA/QC
• Chapter 2: Planning and Documentation
ChapterS: General QA/QC Methods
• Chapter 4: Evaluating the Uncertainty of Emission Estimates
ChapterS: 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 Rating System (DARS)
These documents can be downloaded from EIIP's web site at: http ://www. epa. gov/ttn/chief/eiip/.
To assist State and local agencies in the QA process, EPA will make available to these agencies the
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QA checks that EPA may run on their submitted data. State, local and Tribal agencies may decide to pre-
screen their data using these QA checks prior to submitting their data to EPA. For example, EPA has
prepared QA/QC software for the criteria and toxics NEI. This software is located on EPA's Chief web
site at: http://www.epa.gov/ttn/chief/nif/index.htmltfqa. State, local and Tribal agencies are encouraged to
run this software on their inventories prior to submitting the inventories to EPA to identify and correct QA
issues.
On May 5, 2000, EPA issued Order 5360.1 A2 which revised EPA's quality assurance policy. This
policy revision established amoung other things, the requirement for Quality Assurance Project Plans
(QAPPs) for all EPA supported programs that generate environmental data. The EPA Office of the
Inspector General has determined that emission inventories should be included under the provisions of
5360.1 A2 (see http://www.epa.gov/quality/qa docs.html#EPArqts for a link to 5360.1 A2). Specific
information and guidance on the preparation of QAPPs can be found at the following URL:
http://www.epa.gov/quality/. The document "Guidance for Quality Assurance Project Plans (QA/G-5)"
gives very detailed information on how to prepare QAPPs (see http://www.epa.gov/quality/qapps.html).
States should consult with their specific Regional Office to determine how to meet the QAPP
obligation for the SIP inventory development.
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SECTION 7
REFERENCES
1. Recommendations for Improving Western Vistas: Report of the Grand Canyon Visibility Transport
Commission to the United States Environmental Protection Agency, The Grand Canyon Visibility
Transport Commission, June 1996. (Web address: http://www.westgov.org/wga/publicat/epafin.htm')
2. Introduction to the Emission Inventory Improvement Program, Volume I, U.S. Environmental
Protection Agency, Research Triangle Park, NC, EPA-454/R-97-004a, July 1997. (Web address:
http://www.epa.gov/ttn/chief/eiip/techreport/volume01/index.html)
3. Guidance on the Use of Models and other Analysis in Attainment Demonstrations for the 8 Hour Ozone
NAAQS, U.S. Environmental Protection Agency, Research Triangle Park, NC, To be published 2005.
(Web address: http://www.epa.gov/ttn/scram/)
4. 2002 Base Year Emission Inventory SIP Planning: 8-hr Ozone, PM25 and Regional Haze Programs,
U.S. Environmental Protection Agency, Research Triangle Park, NC, November 18, 2002. (Web
address: http://www.epa.gov/ttn/chief/eidocs/2002baseinven 102502new.pdf)
5. Quality Assurance Procedures and DARSSoftware, Chapter 2, Volume VI, EIIP, U.S. Environmental
Protection Agency, Research Triangle Park, NC, 1997. (Web address: http://www.epa.gov/ttn/
chief/eiip/techreport/volume06/index.html)
6. 1999 National Emission Inventory Preparation Plan - Revised (February 2001), U.S. Environmental
Protection Agency, Research Triangle Park, NC, 1999. (Web address: http://www.epa.gov/ttn/chief/
net/nei plan feb2001.pdf)
7. Guidelines for Estimating and Applying Rule Effectiveness for Ozone/CO State Implementation Plan
Base Year Inventories, EPA452/R-92-010, U.S. Environmental Protection Agency, Research Triangle
Park, NC, November 1992. (Web address: http://www.epa.gov/ttn/chief/old/eidocs/
454r92010 novl992.pdf)
8. Mexico Emissions Inventory Program Manuals, Volume VIII - Modeling Inventory Development,
Final, prepared for the Western Governors' Association and the Binational Advisory Committee,
February 16,2000. (Web address: http://www.epa.gov/ttn/catc/dirl/modeldev.pdf)
9. Wilkinson, J.G., C.F. Loomis, D.E. McNally, R.A. Emigh, T.W. Tesche. Technical Formulation
Document: SARMAP/LMOS Emissions Modeling System (EMS-95), AG-90/TS26 and AG-90/TS27,
prepared for the Lake Michigan Air Directors Consortium, Des Plaines, IL and The Valley Air
Pollution Study Agency, Technical Support Division, Sacramento, CA, prepared by Alpine
Geophysics, Pittsburgh, PA, 1994.
10. Compilation of Air Pollutant Emission Factors, AP-42, Fifth Edition and Supplements, U.S.
Environmental Protection Agency, Research Triangle Park, NC, 1997. (Web address:
http://www.epa.gov/ttn/chief/publications.htmlfffactor)
11. Procedures for the Preparation of Emission Inventories for Carbon Monoxide and Precursors of
Ozone, Volume I, EPA-450/4-91-016, U.S. Environmental Protection Agency, Research Triangle Park,
NC, May 1991.
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12. Procedures for Preparing Emissions Projections, EPA-450/4-91-019, U.S. Environmental Protection
Agency, Research Triangle Park, NC, July 1991. (Web address:
http://www.epa.gov/ttn/chief/publications.htmlffgeneral)
13. Preferred and Alternative Methods for Estimating Air Emissions, Volume II, Point Sources Preferred
Methods, EIIP, U.S. Environmental Protection Agency, Research Triangle Park, NC. (Web address:
http://www.epa.gov/ttn/chief/eiip/techreport/volume02/index.html)
14. Preferred and Alternative Methods for Estimating Air Emissions, Volume III, Area Sources Preferred
Methods, EIIP, U.S. Environmental Protection Agency, Research Triangle Park, NC. (Web address:
http://www.epa.gov/ttn/chief/eiip/techreport/volume03/index.html)
15. Preferred and Alternative Method for Estimating Air Emissions, Volume IV, Mobile Sources, Chapter
2, Use of Locality Specific Transportation Data for the Development of Mobile Source Emission
Inventories, EIIP, U.S. Environmental Protection Agency, Research Triangle Park, NC, September
1996. (Web address: http://www.epa.gov/ttn/chief/eiip/techreport/volume04/index.html)
16. Procedures for Emission Inventory Preparation, Volume IV: Mobile Sources, EPA-450/4-81-016d
(Revised), U.S. Environmental Protection Agency, Research Triangle Park, NC, September 1992.
(Web address: http://www.epa.gov/otaq/invntory/r92009.pdf)
17. Preferred and Alternative Method for Estimating Air Emissions, Volume IV, Mobile Sources, Chapter
3, Guidance for Estimating Lawn and Garden Activity Levels, EIIP, U.S. Environmental Protection
Agency, Research Triangle Park, NC, September 1997. (Web address:
http://www.epa.gov/ttn/chief/eiip/techreport/volume04/index.html)
18. Procedures for Emission Inventory Preparation, Volume IV: Mobile Sources, U.S. Environmental
Protection Agency, Office of Mobile Sources and Office of Air Quality Planning and Standards, EPA
420/R-92-009. December 1992. (Web address: http://www.epa.gov/otaq/invntory/r92009.pdf)
19. Commercial Marine Activity for Great Lake and Inland River Ports in the United States, U.S.
Environmental Protection Agency, Office of Mobile Sources, Assessment and Modeling Division,
Final Report, EPA 420-R-99-019. September 1999. (Web address: http://www.epa.gov/otaq/models/
nonrdmdl/c-marine/r99019.pdf)
20. Commercial Marine Activity for Deep Sea Ports in the United States, U.S. Environmental Protection
Agency, Office of Mobile Sources, Assessment and Modeling Division, Final Report. June 30, 1999.
(Web address: http://www.epa.gov/otaq/models/nonrdmdl/c-marine/r99020.pdf)
21. Preferred and Alternative Methods for Estimating Air Emissions, Volume V, Biogenic Sources
Preferred Methods, EIIP, U.S. Environmental Protection Agency, Research Triangle Park, NC,
May 1996. (Web address: http://www.epa.gov/ttn/chief/eiip/techreport/volume05/index.html)
22. Emission Methodology for Oil and Gas Seeps, California Air Resources Board, Sacramento, CA,
1993. (Web address: http://www.arb.ca.gov/emisinv/areasrc/fullpdf/full9-2.pdf)
23. Example Documentation Report for 1990 Base Year Ozone and Carbon Monoxide State
Implementation Plan Emission Inventories, EPA-450/4-92-007, U.S. Environmental
ProtectionAgency, Research Triangle Park, NC, March 1992. (Web address:
http ://www. epa. gov/ttn/chief/eidocs/exdocument.pdf)
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24. Example Emissions Inventory Documentation for Post-1987 Ozone State Implementation Plans, EPA-
450/4-89-018, U.S. Environmental Protection Agency, Research Triangle Park, NC, October 1989.
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APPENDIX A
CONSOLIDATED EMISSIONS REPORTING RULE (CERR)
The Consolidated Emissions Reporting Rule (CERR) was published as a final rule in the Federal
Register on June 10,2002 (FR June 10,2002, 39602-39616). It has been subsequently codified in the Code
of Federal Regulations as 40 CFR Part 51 Subparts A and Q.
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 51
[AD-FRL-7223-8]
RIN 2060-AH25
Consolidated Emissions Reporting
AGENCY: Environmental Protection Agency (EPA)
ACTION: Final rule
SUMMARY: This action simplifies and consolidates emission
inventory reporting requirements to a single location within the
Code of Federal Regulations (CFR), establishes new reporting
requirements related to PM2.5 and regional haze, and establishes
new requirements for the statewide reporting of area source and
mobile source emissions. Many State and local agencies asked EPA
to take this action to: consolidate reporting requirements;
improve reporting efficiency; provide flexibility for data
gathering and reporting; and better explain to program managers
and the public the need for a consistent inventory program.
Consolidated reporting should increase the efficiency of the
emission inventory program and provide more consistent and uniform
data.
DATES: The regulatory amendments announced in this rule take
effect on August 9, 2002.
ADDRESSES: Docket. Supporting material used in developing the
proposal and final regulatory revisions is contained in Docket
Number A-98-40. This docket is available for public inspection
and copying between 8:30 a.m. and 5:30 p.m., Monday through
Friday. The address of the EPA air docket is: Air and Radiation
Docket and Information Center (6102), Attention Docket Number
A-98-40, U.S. Environmental Protection Agency, 401 M Street, SW,
Washington, D.C. 20460. The Docket is located in Room M-1500,
Waterside Mall (ground floor). The telephone number for the EPA
air docket is (202) 260-7548. A reasonable fee may be charged for
copying.
FOR FURTHER INFORMATION CONTACT: William B. Kuykendal, Emissions,
Monitoring, and Analysis Division (MD-D205-01), Office of Air
Quality Planning and Standards, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, 27711, Telephone:
(919) 541-5372, email: kuykendal.bill@epa.gov.
SUPPLEMENTARY INFORMATION:
I. AUTHORITY
Sections 110 (a) (2) (F) , 110 (a) (2) (K) , 110 (a) (2) (J) , 110 (p) ,
172 (c) (3), 182 (a) (3), 187 (a) (5), 301 (a) of the Clean Air Act.
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II. BACKGROUND
Emission inventories are critical for the efforts of State,
local, and federal agencies to attain and maintain the National
Ambient Air Quality Standards (NAAQS) that EPA has established for
criteria pollutants such as ozone, particulate matter, and carbon
monoxide. Pursuant to its authority under section 110 of Title I
of the Clean Air Act (CAA), EPA has long required State
Implementation Plans (SIPs) to provide for the submission by
States to EPA of emission inventories containing information
regarding the emissions of criteria pollutants and their
precursors (e.g., volatile organic compounds (VOC)). The EPA
codified these requirements in 40 CFR part 51, subpart Q in 1979
and amended them in 1987.
The 1990 Amendments to the CAA revised many of the provisions
of the CAA related to the attainment of the NAAQS and the
protection of visibility in mandatory Class I Federal areas
(certain national parks and wilderness areas). These revisions
established new periodic emission inventory requirements
applicable to certain areas that were designated nonattainment for
certain pollutants. For example, section 182 (a) (3) (A) required
States to submit an emission inventory every three years for ozone
nonattainment areas beginning in 1993. Emissions reported must
include VOC, nitrogen oxides (NOX ), and carbon monoxide (CO) for
point, area, mobile (onroad and nonroad), and biogenic sources.
Similarly, section 187 (a) (5) required States to submit an
inventory every three years for CO nonattainment areas for the
same source classes, except biogenic sources. The EPA, however,
did not codify these statutory requirements in the Code of Federal
Regulations (CFR), but simply relied on the statutory language to
implement them.
The EPA has promulgated the NOX SIP Call (§51.121) which calls
on the affected States and the District of Columbia to submit SIP
revisions providing for NOX reductions in order to reduce the
amount of ozone and ozone precursors transported among States. As
part of that rule, EPA established emissions reporting
requirements to be included in the SIP revisions to be submitted
by States in accordance with that action.*
This rule consolidates the various emissions reporting
requirements that already exist into one place in the CFR,
establishes new reporting requirements related to PM2.5 and
XEPA recognizes that the United States Court of Appeals has
remanded certain issues regarding the NOX SIP call to the Agency.
See Michigan v. EPA, 213 F. 3d 663 (D.C. Cir. 2000), and
Appalachian Power Co. v. EPA, No. 99-1268, United States Court of
Appeals for the District of Columbia Circuit, slip op. Issued
June 8, 2001. Those issues, however, do not include the
reporting requirements and the consolidation of those
requirements does not represent any prejudgment of the issues on
remand to the Agency.
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regional haze, and establishes new requirements for the statewide
reporting of area source and mobile source emissions. This rule
also includes the reporting provisions for the NOX SIP call. The
NOX SIP call reporting requirements are very detailed and are
specified in 40 CFR 51.122; this rule references these
requirements.
In this action, we refer to the required types of inventories
as the following:
• Annual inventories
• 3-year cycle inventories
The EPA anticipates that States will use data obtained through
their current annual source reporting requirements (annual
inventories) to report emissions from larger point sources
annually. States will need to get data from smaller point sources
only every third year. States may also take advantage of data
from Emission Statements that are available to States but not
reported to EPA. As appropriate, States may use these data to
meet their reporting requirements for point sources. States will
also be required to inventory area and mobile source emissions on
a Statewide basis for the 3-year cycle inventory. We will be
furnishing each State the National Emission Inventory (NEI) which
should be a good starting point for estimating area source
emissions. Mobile source emissions should be estimated by using
the latest emissions models and planning assumptions available.
The MOBILE emissions factor model should be used to estimate
emissions from on-road transportation sources, in combination with
the latest available estimates of vehicle miles traveled (VMT).
The NONROAD model can be used for off-road mobile sources as
appropriate. By merging this information into a comprehensive
emission inventory, State and local agencies may do the following:
• measure their progress in reducing emissions.
• have a tool they can use to support future trading
programs.
• set a baseline from which to do future planning.
• answer the public's request for information.
We intend these inventories to help nonattainment areas develop
and meet SIP requirements to reach the NAAQS and comply with the
regional haze regulation.
For the first time, all States will need to inventory direct
emissions of PM2.5 and ammonia (NH3) _ Since PM2.5 is both a NAAQS
pollutant and a major contributor to visibility impairment, we
feel it is appropriate to begin collecting this emissions data.
These PM2.5 related data elements are needed as input to emission
models. Emissions data will also be a factor in the development
of PM2.5 nonattainment area boundaries.
The Administrator has determined that States should submit
statewide annual and 3-year cycle inventories for PM10, PM2.5, and
regional haze, consistent with the data requirements for 03 and
CO. Sections 110 (a) (2) (F) and 172 (c) (3) provide ample statutory
authority for this rule. Section 110 (a) (2) (F) provides that SIPs
are to require "as may be prescribed by the Administrator...
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(ii)periodic reports on the nature and amounts of emissions and
emissions-related data from such sources." Section 172 (c) (3)
provides that SIPs for nonattainment areas are to "include a
comprehensive, accurate, current inventory of actual emissions
from all sources of the relevant pollutant or pollutants in such
area, including such periodic revisions as the Administrator may
determine necessary to assure that the requirements of this part
are met." Additional statutory authority for emissions
inventories from 1-hour ozone nonattainment areas is provided by
section 182 (a) (3) (A) and for emissions inventories from CO
nonattainment areas is provided by section 187 (a) (5) . Section
301 (a) provides authority for EPA to promulgate regulations
embodying these provisions.
What is the purpose of the Consolidated Emissions Reporting
Rule (CERR)?
The purpose of this rule is fivefold:
• simplify emissions reporting,
• offer options for data submittal,
• unify reporting dates for various categories of
inventories,
• include reporting fine particulate matter and NH3
(Note: Initially PM2 5 and NH3 reporting will only be
required for area and mobile sources. States will be
required to commence point source reporting of PM2.5
and NH3 at a later date as detailed in §51.30.) and,
• include Statewide reporting for area and mobile
sources.
Previous requirements may have, at times, led to inefficient
reporting. This rule provides for options for reporting that
allow States to match their ongoing activities with federal
requirements. This action also consolidates existing and new
requirements of emission inventory programs for annual and 3-year
cycle inventories.
Who will have to comply with the CERR requirements?
This rule will apply to State air pollution control agencies.
In the special case where a State Implementation Plan provides for
independent jurisdiction for local air pollution control agencies,
these local agencies will also have to comply with the CERR
requirements. In the rule, we have adopted "plain English
language". When "you" is used we mean the State or local agency.
When "we" is used, EPA is meant.
How will this rule affect Tribes?
One of the principal goals of the Tribal Authority Rule (TAR)
is to allow tribes the flexibility to develop and administer their
own CAA programs to as full an extent as they elect to do, while
at the same time ensuring that the health and safety of the public
are protected. In seeking to achieve this principal goal, the TAR
adopts a modular approach, that is, it authorizes tribes to
develop and implement only discrete portions of CAA programs,
instead of entire complex programs. Neither the CAA nor the TAR
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require tribes to adopt and manage CAA programs. Accordingly, the
tribes are not required to develop an emissions inventory for
sources within their jurisdiction. However, the emissions
inventory is an important part of understanding the air quality
status on the reservations and would be helpful in determining the
best approach for addressing any air quality issues identified.
Therefore, EPA expects that many of the tribes will wish to
develop emissions inventories. This rule can provide valuable
guidance to the tribes on how to develop these inventories, for
example, by pointing out that any inventory data that are
collected should be quality assured, and explaining how to do so.
In addition, it would be very helpful if this information were
recorded in EPA's National Emission Inventory (NEI) data format.
This would make it possible to include the tribal data in the NEI
which should facilitate future efforts by EPA when working with
the tribes to develop air quality plans for reservations.
How are the CERR's requirements different from existing
requirements ?
(a) additional pollutants
Your State's inventory will add PM2.5 and the precursor NH3 to
the criteria pollutants. (Note: Initially PM2 5 and NH3 reporting
will only be required for area and mobile sources. States will be
required to commence point source reporting of PM2.5 and NH3 at a
later date as detailed in §51.30.)
(b) geographic coverage of inventory
Your State now reports point source emissions statewide and
emissions from area and mobile sources by nonattainment area.
Your State's new inventory will be statewide by county for all
source types, regardless of the attainment status.
(c) frequency of reporting
Your State will continue to report emissions from larger point
sources (See Table 1 of Appendix A) annually. Your State has a
choice to report smaller point sources every three years or one-
third of the sources each year. Your State will continue to
report emissions from nonattainment areas for area and mobile
sources every three years. Area and mobile source emissions in
all other areas will be required to be reported for the first
time, also every three years.
How will EPA use the data collected under this reporting
requirement?
The EPA uses emission inventories for the following purposes:
• modeling analyses,
• projecting future control strategies,
• tracking progress to meet requirements of the CAA,
• calculating risk and
• responding to public inquiries.
How will others use my data collected under this requirement?
Some States need emissions data for areas outside their
borders. Programs such as the Ozone Transport Assessment Group,
the Ozone Transport Commission NOX Baseline Study, and the Grand
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Canyon Visibility Transport Commission demonstrated this need. As
we recognize pollution as a regional problem, agencies will need
multistate inventories more often to do such things as regional
modeling. The EPA has established five Regional Planning
Organizations (RPOs) that cover the nation. The RPOs are
initially charged with developing regional strategies to address
visibility concerns. Each RPO will be developing a regional
emission inventory that will be used in regional scale modeling.
We can meet our common needs by creating a central repository
of data from State and local agencies, or a group of regional
emissions databases. Such repositories offer the advantage of
ready access and availability, common procedures for ensuring the
quality of data, and an ability to meet the general needs of many
potential users.
What happens if EPA doesn't get my agency's emissions data?
We have structured this rule and our own emission inventory
development plans so that the chance of this happening is
minimized. We will develop our own preliminary National Emission
Inventory (NEI) and furnish it to each State. You may choose to
use the NEI as a starting point for development of your Statewide
emission inventory. We strongly urge you to develop your own
emission inventory. However, you may choose to accept all or part
of the area source, mobile source and biogenic portions of the NEI
as estimated by EPA without change and use these as your submittal
to EPA. To do this, you can certify that you accept the EPA
developed portions as your own estimates. Since you have been
required to submit point source inventories to us since 1979 and
since today's action reduces your point source reporting burden,
you cannot use the NEI to satisfy your obligation to submit point
source data.
If we don't receive your emissions information at the time this
rule specifies, we'll use our preliminary NEI to produce final
emissions estimates for your geographical area.
The CAA provides for certain actions if we do not receive your
data, depending on the type of area, the pollutants involved, and
the type of inventory submittal in question. All of the emissions
information submissions specified by this rule are required
submissions under section 110 (p) of the CAA. There are also
required submissions under the provisions of each existing
approved State Implementation Plan, by virtue of section
110 (a) (2) (F) (ii) . If States do not make the required data
submissions, we may make a finding of failure to implement the SIP
even though we have substituted our preliminary estimates for the
data you were required to submit but did not. In some cases, for
example the three-year periodic emission inventories in ozone
nonattainment areas, the submissions are statutorily required SIP
revisions. Accordingly, we may also or instead make a finding of
failure to submit.
III. COMMENTS RECEIVED ON THE PROPOSAL
The forty-five day comment period for the May 23, 2000 (at 65
33268) proposal expired on July 7, 2000. We received comments
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from forty-one respondents. These comments were submitted by
twenty-eight State and local agency representatives, eleven
industrial organizations and two environmental organizations. We
have addressed all comments in detail and placed them in the
docket. The major comments and their resolution are discussed
below. As an aid to the reader, we have grouped related comments
under broad topical headings.
A. Hazardous Air Pollutant Reporting
A number of commenters responded to the section in the preamble
of the proposed rule, "What Additional Reporting Requirements Is
EPA Considering?". This section discussed how EPA might require
the reporting of hazardous air pollutants (HAPs) in the final
rule. The predominant comment was that EPA should not include HAP
reporting requirements in the final rule until the specific HAP
reporting requirements were proposed. We have carefully
considered this comment and agree. We have limited this
rulemaking to the criteria pollutants including PM2>5 and NH3. We
plan to develop HAP reporting measures at a future date. At that
time, we will address all other HAP related comments.
B. Criteria Point Source Reporting
We received several comments addressing the proposed
applicability threshold (the emission limit at which a State is
required to report a facility as a point source), the associated
basis for determining applicability (applicability based on either
"actual" or "Title V permitted" criteria pollutant emissions), and
reporting frequency.
Existing rules require State agencies to annually report
criteria pollutant emission inventory information for all
qualifying point sources statewide. The reporting thresholds in
place prior to this rule were for any point source with actual
emissions greater than or equal to any one of the following
levels: 100 tons per year for SOX, NOX, VOC, and PM10; 1000 tons
per year for CO and 5 tons per year for lead. This rule revises
the applicability threshold by assigning the point sources into
two categories termed Type A (large point sources) and Type B (all
point sources), and reduces the reporting frequency for the
smaller sources. Qualification as either a Type A or B source is
still based upon a point source's actual emissions of the same
criteria pollutants. Under our new terminology, all of the
sources that were defined as a point source under the old
thresholds are defined as Type B sources. Type A sources are the
larger emitting sources and are a subset of the Type B sources.
The reporting thresholds for Type A and Type B sources are
presented in Table 1 of Appendix A.
Several State and local agencies indicated that the proposed
Type A and B categories and associated emission thresholds were
confusing and increased their reporting burden. These commenters
recommended that we use the CAA's Title V definition of major
source instead of the two subsets for determining point source
applicability for this rule. (Note: for criteria pollutants, a
major source under Title V is any stationary source or any group
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of stationary sources located within a contiguous area and under
common control that has the potential to emit 100 tons per year.
However, sources located in nonattainment areas can have lower
emission thresholds that would define them as major sources.) In
addition to lowering the applicability threshold, use of the Title
V definition would shift the basis for determining the
applicability of the rule from "actual" to "potential" emissions.
Commenters advocating the use of the Title V major source
definition indicated that they maintain emission inventory data on
all of their Title V sources and their reporting burden would
increase if we required them to designate sources in their
database as Type A (large point sources) vs Type B (all point
sources).
We also received comments opposing the use of the Title V major
source definition for determining applicability. These commenters
indicated that such a requirement would increase their reporting
burden since they currently do not gather the required emission
inventory information for all of the Title V sources located in
their jurisdiction.
In addition to the Title V applicability issue, we received
comments, both advocating and opposing, the proposed 10 tpy VOC
applicability threshold for sources located in all ozone
nonattainment areas. Commenters opposed to the proposed VOC
applicability threshold recommended that the existing 10 tpy level
be raised to the major source threshold. (The major source
threshold for VOC varies between 10 and 100 tons per year of
potential emissions depending on the ozone nonattainment
classification.) Other commenters advocated finalizing the
proposed 10 tpy VOC applicability threshold.
Existing emission inventory reporting rules require State and
local agencies to report emission inventory information for all
qualifying point sources on an annual basis. The frequency for
reporting emission inventory information was revised in the
proposal. As proposed, States would be required to report
emission inventory data for Type A (large point sources) on an
annual basis and Type B (all point sources) on a 3-year cycle. In
response to this revision, we received comments both opposing the
reduction and comments advocating further reductions in the
reporting frequency. Commenters opposing the reduction
recommended that we maintain the existing annual reporting
frequency for both Type A and Type B sources. Commenters
advocating further reporting reductions wanted to increase the
time for reporting Type B sources from 3 to 5 years.
After careful consideration of the comments on the point source
applicability and reporting, we have decided to promulgate the
proposed Type A (large point sources) and Type B (all point
sources) categories and the associated criteria pollutant emission
thresholds, except for VOC, and the reporting frequency.
Regarding the VOC applicability threshold for sources located in
ozone nonattainment areas, we have decided to revise this
threshold, proposed as 10 tpy for all ozone nonattainment areas,
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to be consistent with the CAA definition of major source in the
respective ozone nonattainment areas except that it will apply to
actual rather than to potential emissions.
When assessing comments on applicability and reporting issues,
we considered the fact that this proposal was developed with input
from a work group that included representatives from three states
(California, New Jersey and Texas) and EPA. In addition to this
workgroup, we maintained an active dialog about this proposal with
a larger number of States through the State and Territorial Air
Pollution Program Administrators (STAPPA) and the Association of
Local Air Pollution Control Officials (ALAPCO). The fact that
this proposal received strong support from the same State and
local agencies that are responsible for complying with this rule
was a factor in our decision to promulgate these revisions.
Another factor that impacted our decision is that the revisions to
both the point source category and reporting frequency were
proposed to reduce the reporting burden on State agencies.
Because of their large size, the annual requirement for Type A
sources will affect relatively few sources, yet capture a large
percentage of the emissions that would be reported if all Type B
sources reported annually. Thus, we believe that the promulgated
revisions to applicability threshold and reporting frequency will
not adversely impact our effort to implement the CAA nor diminish
the usefulness of emission inventory data accessible to the
public.
We are sympathetic with the additional reporting burden that
this rule would place on those agencies that currently collect the
required items of emission inventory information on all Title V
sources, if they were required to remove all data for smaller
point sources when preparing their annual report on Type A (large
point sources) or their triennial report on Type B (all point
sources). Recognizing the need to provide State agencies with
additional reporting flexibility and to reduce reporting burden,
the final rule is explicit that we will accept emission inventory
information submitted by the States that was collected and stored
using any more stringent definition of point source and basis for
determining source applicability within the Title V definition.
Thus, an annual submission of a point source emission inventory
that uses the Title V major source definition and potential
emissions as qualification factors for inclusion in a State's
emission inventory will be accepted.
We believe that the promulgated rule establishes the baseline
or minimal data requirements needed to implement the CAA. We
believe that requiring State and local agencies to report sources
below the baseline established by this rule would increase the
reporting burden with only a minimal increase in the usefulness of
the inventory. However, this rule is not intended to relax
existing reporting thresholds and frequencies established by State
and local agencies. We recognize that State and local agencies
may need emission information on sources more frequently and below
the baseline established by this rule in order to manage their air
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quality. Thus States and local agencies will have the flexibility
to establish lower reporting thresholds and more frequent
reporting requirements than those promulgated in this rule.
Several commenters noted that the applicability limits for
sources subject to annual reporting specified in §51.1 were
incorrect. We agree with these comments and have appropriately
modified the regulatory language.
One commenter noted that many of the data elements required by
this rule for a point source are more appropriate for an "emission
unit". The commenter recommended that the final rule include
thresholds for reporting emission unit or stack data within a
point source. After reviewing this comment, we believe that it
would be confusing and would add additional reporting burden to
require reporting thresholds below the facility level. Therefore,
we have decided not to expand the reporting threshold requirements
below the facility level. However, if States choose to report at
the sub-facility level, Table 2a in Appendix A includes provisions
for reporting at the point, process and stack levels.
C. Criteria Area/Mobile/Biogenics Reporting
One commenter noted that we are requiring States to submit
criteria pollutant emission estimates for all counties regardless
of an area's classification (attainment or nonattainment) and that
States, having historically done a good job when concentrating on
problem areas, generally do not have the resources to perform a
good job on every county especially when estimating area, nonroad,
and mobile sources in small metropolitan areas. The commenter
recommended that we develop these estimates and not burden the
States.
For the 1996 emission inventory, we prepared an estimate of the
criteria pollutants from point, area, mobile, nonroad and biogenic
sources and provided these data to the States for their review
prior to them initiating their emission inventory reporting
effort. The States were able to use the EPA estimates as they
prepared their 1996 emission inventory. For area sources, mobile
sources and biogenic sources, we offered States the option of
either notifying us that they agreed with our estimate or revising
the estimate and providing us with updated information. The
States were still required to provide State developed estimates
for point sources. Recognizing the burden to States, we plan to
continue to provide States with our emissions estimate for their
review and use in future emission inventory preparation.
Another commenter noted that in the proposed preamble section
"What happens if EPA doesn't get my agency's emissions Data?" that
we state that we will generate the non-supplied data using our own
techniques. The commenter wondered if the State could simply
accept the data we developed. The commenter also stated that if
we developed data not supplied by the State, that we should label
the data as our estimates. The commenter stated that our
estimates made without State agreement could be challenged with
due cause. We have rewritten this section of the preamble to
explicitly state that we will furnish each State with an inventory
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that we prepared for that State (the National Emission Inventory
(NEI)). The States may use the NEI as they prepare their State
inventories. The States are strongly encouraged to improve upon
our NEI estimates. However, they may choose to resubmit all or
part of the NEI to us as their State's inventory. If they do
this, then they are certifying that the adopted NEI portions are
their estimates. If States ignore the requirements of this rule
and do not make a timely inventory submittal to us, we will use
our NEI to fill data gaps that will allow us to proceed with our
various analyses.
D. PM2 5 and Precursors
One commenter stated that we should revise our list of reported
pollutants under § 51.20 to include only specific compounds or
groups of compounds. This commenter wanted us to remove "PM2>5
precursors" from our list of pollutants. We have carefully
evaluated this comment and agree that the term "PM2.5 precursor" is
not precise. There is not an acceptable enforceable definition of
this term. When "PM2.5 precursor" was used in the proposed rule,
the compounds or groups of compounds SOX, VOC, NOX and NH3 were
meant. Since the CERR specifically requires the reporting of SOX,
VOC and NOX, we have dropped the term "PM2.5 precursors" and
substituted NH3 in the list of required pollutants. The proposed
rule specifically stated that NH3 was a "PM2>5 precursor", so this
modification merely simplifies the list of required pollutants; it
does not add a new pollutant to the list.
E. Tools
Several commenters stated that the emissions estimation tools
were inadequate to produce acceptable emission inventories. These
commenters pointed out specific types of estimation tools that
they believed were either not available at all or were not
adequate. These included EPA-developed models including the
MOBILE model, the NONROAD model, and the PART model and emission
factors, especially ones for PM2>5 and NH3. We agree that
improvements in many of the emission estimation techniques are
highly desirable, particularly in some of the areas identified by
the commenters. However, we know that there will always be the
opportunity to improve emission estimation techniques and that
this is an evolutionary process. The CERR does not require the
use of any specific emission estimation technique. There are
emission estimation techniques available for all of the required
pollutants and their major sources. Therefore, we believe that
State or local agencies should be able to make emission inventory
submittals that will be acceptable to EPA using current state-of-
the-art techniques.
F. Reporting Deadlines/schedules
As proposed, this rule would have been applicable for the 1999
reporting year. Commenters noted that States had already begun
compiling their 1999 point source inventories. These commenters
would like for us to incorporate a phase-in or implementation
schedule into the rule that would allow sufficient time for some
agencies to go through a rulemaking process to align their
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requirements with the new requirements specified by this rule. In
addition, lead time is required for some agencies to conform to
the standard data format for the first time. After careful
consideration of these comments, we have decided to change the
first year that States will be required to report under this rule.
The first "Annual Cycle Inventory" will be for the year 2001. The
first "Three-year Cycle Inventory" will be for the year 2002.
Thus when States begin to develop their 2001 annual cycle emission
inventory, they will only be required to submit the plant
information and emission data for Type A (large point sources) as
outlined by this rule. Since the basic requirement for point
source reporting is not new, the States should be able to comply.
Another reporting related issue identified by the commenters
was the difference in the reporting schedule between the proposed
rule which requires all States to report annual emissions for
certain sources and the NOX SIP call rule which requires only
affected States to report ozone season emissions. Some commenters
recommended that the reporting schedule for these two inventories
should be the same. Specifically, the NOX SIP call specifies that
States must report their ozone season emissions inventory for
subject facilities within 12 months after the end of the reporting
year. The proposed rule would require States to report both
annual and the 3-year cycle inventories for subject facilities
within 17 months after the end of the reporting year. The
commenters recommended that the reporting schedule for the NOX SIP
call inventory be revised and made consistent with the annual and
three-year cycle inventories.
After considering the comment, we have decided to maintain the
NOX SIP call reporting schedule on its 12-month cycle.
Maintaining the 12-month reporting requirement for the NOX SIP
call inventory allows both the States and us to take note of
higher than planned emissions early enough to give an opportunity
for action before the next ozone season. Furthermore, for many
large NOX sources (e.g., utilities) that must report directly to
us, the NOX SIP call rule does not require any State reporting.
Thus, the 12-month reporting requirement is not a burden on the
States for these sources. We will continue to consider the points
made by the commenters in light of the experience that both of us
have with the 12 month preparation and submission of annual
inventories. We may re-open this requirement for comment at a
later date.
One commenter noted that we did not revise 40 CFR § 51.321 to
agree with the proposed § 51.35. Each of these sections contains
due dates which did not agree. We agree with this comment and
have rewritten both sections to ensure consistency of the
reporting dates.
G. Reporting Stack Data
One commenter noted that while the proposed rule text required
the reporting of stack data every three years, the blocks for
stack data were not checked in Table 2a for the column
"Entire US". We acknowledge that the omission of the checks was a
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mistake in Table 2a for the data elements: 40. Stack Height, 41.
Stack Diameter, 42. Exit Gas Temperature, 43. Exit Gas Velocity
and 44. Exit Gas Flow rate for the columns "Entire US". We have
corrected this; the column "Entire US" has been relabeled "Every 3
Years".
H. Funding Issues
A number of commenters raised the issue of sufficient funding
being available to pay for these new emission inventory
requirements. These commenters questioned whether we would make
additional monies available to the States specifically to comply
with the provisions of the CERR. We are aware that the CERR does
apply additional reporting burden on the States. In this
preamble, under "IV. Administrative Requirements, C. Paperwork
Reduction Act," we have estimated the incremental burden of the
new requirements to be about $2,133,000 per year nationally.
This estimate is based on information supplied by the States to us
during the comment period and assumes that the States will be
doing new work. However, in this preamble, under "II. Background,
What happens if EPA doesn't get my agency's data?" we discuss how
you may use the EPA-supplied NEI in the preparation of your
emission inventory. If you choose to use the NEI estimates for
area, mobile and biogenic sources as your State's estimates, your
cost would be limited to the preparation of your point source
inventory. We acknowledge that quality of this NEI-based
inventory would be lower, but it would satisfy the specific
reporting requirements of the CERR. We hope that future budgets
at both the Federal and State levels will improve emission
inventory funding. For FY 2001, the Congress authorized an
increase in the total air grant funds to the States and the multi-
State Regional Planning Organizations. Some of these funds were
used for emission inventory improvement. However, no new monies
are being made available through this rulemaking.
I. General
Several commenters stated that they support EPA's efforts to
consolidate and improve emission inventory reporting on a national
level. The respondents benefit from the data collected under the
CERR since consistently developed statewide emission inventories
assist in regional planning processes, especially for those
downwind States whose nonattainment status is caused in part by
pollution transported across State boundaries. In addition, the
collection of PM2>5 and NH3 data will support future State efforts
to reach the visibility improvement goals in Class I areas and to
attain the revised PM NAAQS.
We received several comments on our estimate of reporting
burden contained in the proposed rule. These comments are
addressed in this preamble under "IV. Administrative Requirements,
B. Paperwork Reduction Act".
J. EPA Initiated Changes
In addition to the above changes in response to specific
comments, we have made other changes. Most of these changes were
editorial to improve clarity or to correct grammatical mistakes.
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The references to sections 182 (a) (3) (A) and 182 (a) (3) (B) under
"Authority" have been combined to refer to section 182 (a) (3) as a
simplification. An additional reference under "Authority" has
been added for section 110 (p) . The preamble, Section G.
"Executive Order 13132: Federalism", has been revised as discussed
in that section. In the "Background" section of the preamble, we
have added the new subsection "How will this rule affect Tribes?".
This subsection immediately follows "Who will have to comply with
the CERR requirements?" and clarifies how Tribes will be impacted
by this rule. We changed the name of four data elements in Table
2a of Appendix A and relocated one of them in the table. In the
proposed rule the data elements were: 7. Federal ID code (plant),
8. Federal ID code (point), 9. Federal ID code (process) and 37.
Federal ID code (stack number). There is no "Federal ID code".
These data elements were renamed and numbered as follows: 7.
Facility ID code, 8. Point ID code, 9. Process ID code and 10.
Stack ID code. In addition, a check mark was inadvertently
omitted in the proposed rule for data element "10. Stack ID code"
for the column "Annual (Type A Sources)". We have added this
check mark in the final rule. The Glossary in Appendix A was also
revised to include these new names.
In the proposed rule under "§51.40 In what form should my
State report the data to EPA?" and "§51.45 Where should my State
report the data?", we proposed two specific electronic format
options and identified means of reporting these data to us.
Because electronic reporting technology changes frequently and is
expected to become even more efficient in the future, we believe
that structuring the final rule to limit reporting to these
formats in the final rule unnecessarily restricts the flexibility
for both the States and EPA. For this reason, we have revised
both of these sections to allow for the use of new reporting
formats in the future. These changes do not substantively alter
this rule since, at this time, we will support both of the formats
identified in the proposal; the National Emission Trends (NET)
format (renamed as the National Emission Inventory (NEI) format)
and Electronic Data Interchange (EDI) format, based on user needs.
We have also made changes to the portions of the rule that were
concerned with the NOX SIP Call reporting requirements. In the
proposed rule, the NOX SIP Call reporting requirements were
detailed in the regulatory text and in the tables in Appendix A.
However, these requirements are actually established in §51.122
and are presented in detail. In order to avoid confusion and
possible inconsistencies, we have removed the NOX SIP Call
requirements and instead reference them in this rule. Because
§51.122 establishes the reporting requirements, the changes that
we have made to the CERR do not represent new requirements for the
States.
K. Changes Resulting from OMB Review
In their review of the Paperwork Reduction Act portion of this
rule, the Office of Management and Budget (OMB) has raised
concerns about that portion of the Information Collection Request
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that addresses the reporting of point source PM2.5 and NH3
emissions. Rather than delay the compliance date of the rule, EPA
has elected to delay compliance with that portion which concerns
the collection of information on point source PM2.5 and NH3
emissions. As modified, the rule now provides that States must
commence reporting point source emissions of PM2.5 and NH3 on June
1, 2004 provided that, at least 60 days prior, we have published
an approved revised ICR which addresses this subsection of the
rule. If we fail to meet the deadline for June 1, 2004 reporting,
States must commence reporting point source emissions of PM2>5 and
NH3 on the next applicable reporting date that is at least 60 days
after we publish an approved ICR addressing this subsection of the
rule.
IV. ADMINISTRATIVE REQUIREMENTS
A. Docket
The docket for this regulatory action is A-98-40. The docket
is an organized and complete file of all the information submitted
to, or otherwise considered by, EPA in the development of this
rulemaking. The principal purposes of the docket are: (1) To
allow interested parties a means to identify and locate documents
so that the parties can effectively participate in the rulemaking
process and (2) to serve as the record in case of judicial review
(except for interagency review materials). The docket is
available for public inspection at EPA's Air Docket, which is
listed under the ADDRESSES section of this document.
B. Executive Order 12866, Regulatory Planning and Review
Under Executive Order 12866 (58 FR 51735, October 4, 1993), EPA
must determine whether the regulatory action is "significant" and
therefore subject to review by the Office of Management and Budget
(OMB) and the requirements of the Executive Order. The Executive
Order defines "significant regulatory action" as one that is
likely to result in a rule that may:
(1) Have an annual effect on the economy of $100 million or
more or adversely affect in a material way the economy, a sector
of the economy, productivity, competition, jobs, the environment,
public health or safety, or State, local, or tribal governments or
communities;
(2) create a serious inconsistency or otherwise interfere with
an action taken or planned by another agency;
(3) materially alter the budgetary impact of entitlements,
grants, user fees, or loan programs, or the rights and obligation
of recipients thereof; or
(4) raise novel legal or policy issues arising out of legal
mandates, the President's priorities, or the principles set forth
in the Executive Order.
Pursuant to the terms of Executive Order 12866, OMB has
notified EPA that it considers this a "significant regulatory
action" within the meaning of the Executive Order. The EPA has
submitted this action to OMB for review. Changes made in response
to OMB suggestions or recommendations have been documented in the
public record.
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C. Paperwork Reduction Act
The information collection requirements in this rule have been
submitted for approval to the Office of Management and Budget
(OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq.
Earlier the Office of Management and Budget approved the current
information collection requirements in part 51 under the Paperwork
Reduction Act and has assigned OMB control number 2060-0088 (EPA
ICR No. 0916.09). The Information Collection Request (ICR)
document for the new information collection requirements has been
prepared by EPA (ICR No. 0916.10 ) and a copy may be obtained from
Sandy Farmer by mail at Collection Strategies Division; U.S.
Environmental Protection Agency (2822); 1200 Pennsylvania Ave.,
NW, Washington, D.C. 20460, by email at farmer.sandy@epa.gov, or
by calling (202) 260-2740. A copy may also be downloaded from the
internet at http://www.epa.gov/icr. The information requirements
are not enforceable until OMB approves them.
Today's action revises part 51 to consolidate old reporting
requirements, adds new requirements for PM2 5 and NH3 (Note:
Initially PM2>5 and NH3 reporting will only be required for area
and mobile sources. States will be required to commence point
source reporting of PM2.5 and NH3 at a later date as detailed in
§51.30.) and adds new Statewide reporting requirements for area
and mobile sources. Data from new reporting will be used to:
• support modeling analyses,
• project future control strategies,
• track progress to meet requirements of the CAA, and,
• respond to public inquiries.
The rule contains mandatory information reporting requirements;
EPA considers all information reported under this rule to be in
the public domain and therefore cannot be treated as confidential.
The information in the following table was summarized from ICR
0916.10 and presents the reporting burden estimates.
Reporting Requirement
Current
Statewide Reporting
State agencies
Statewide Reporting
Local agencies
PM2 5 and NH3 Reporting
CERR- Compatible
Reporting
BURDEN ESTIMZ
Number of
Respondents
104
Varies
Varies
104
Varies
HE SUMMARY
Hours per
Respondent
118
1, 120
574
84
84
Total
hours
per year
12,271
42, 630
15,022
8,736
5,376
Total
Labor
Costs Per
Year
$365,756
$1,267,126
$446, 511
$259, 667
$159,795
Total
Annual
Capital
Costs
$218,400
Total
Annual
OSM Costs
$12,480
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I TOTAL I Varies | 1,980 | 84,035 | $2,498,855 | $218,400 | $12,480 |
The reporting burden is broken down into "current
requirements", "statewide area and mobile source reporting
requirements", "PM2.5 and NH3 reporting requirements", and "CERR-
compatible reporting". This has been done to highlight the major
areas changed by the CERR and to show the impact of these changes
on the estimated burden. Significant public comments received
concerning each of these components are discussed, as well as any
resulting changes made to the burden estimates.
The burden hours estimated for all of the emission inventory
reporting requirements in place prior to this rule are labeled
"current" and equal 118 hours per respondent per year. Because of
the streamlining and flexibility offered by the CERR, these
"current" requirements are reduced from the original burden
estimate of 212 hours per respondent; a savings of 94 hours per
respondent per year. Several commenters had stated that the
number of respondents used to estimate burden in the proposed ICR
(i.e., 55) underestimates the total number of respondents, and
does not include local air pollution agencies. The EPA agrees
that the estimated total number of State, Territorial and local
agencies reporting emissions inventory data directly to EPA should
be accounted for. This number was estimated to be 104 respondents
(i.e., 55 State and Territorial agencies, plus 49 local agencies).
As a result, the total burden hours per year for "current"
requirements has increased, but the corresponding hours per
respondent has actually decreased.
The reporting requirements for statewide area and mobile
source reporting add 57,652 hours per year. Several commenters
indicated that they believed the burden estimate in the proposed
ICR to underestimate the actual reporting burden to States. One
commenter stated that "while consolidation may ease the current
burden on some state and local agencies, it will have little
effect on others." The EPA acknowledges that certain State or
local agencies are farther along than others in developing
statewide emission estimation procedures. For States without
nonattainment areas, this would be a new requirement, and the
burden to comply with this requirement may be significant.
Several commenters indicated that the burden to perform this
activity will be zero since they are already performing statewide
inventories. To respond to these comments, the final ICR presents
increased burden estimates for a percentage of State agencies to
comply with this provision of the rule, and the remaining state
respondents were assumed not to incur additional burden for this
activity. Since local agencies are presumed to have jurisdiction
over fewer counties than a State agency, the statewide inventory
burden for local agencies was estimated to be one-half the time
for the State agencies. In addition, area and mobile source
reporting responsibility was only attributed to one-half of the
local agency respondents.
The PM2.5 and NH3 reporting requirements add 8,736 hours per
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year. Several commenters stated that the burden estimate for PM2.5
reporting was low and did not take into account the amount of time
needed to develop emission factors since very little dependable
PM2.5 emissions factor information exists. Several commenters,
however, indicated that the burden to perform this activity will
be zero since they are already compiling PM2 5 inventories for
their own emissions inventory or modeling purposes. The EPA
agrees that burden hours associated with PM2.5 reporting were
underestimated in the proposed ICR. EPA updated the one-time
burden estimate for the final CERR to reflect the time it will
take an average State or local agency to generate a more
representative PM2 5 and NH3 emissions inventory, and if necessary,
to update agency reporting systems to include PM2.5 and NH3. The
revised estimate of 8736 hours includes the effort for a State or
local agency to update their emissions reporting system to include
PM2.5 and NH3. Although States are not required to commence
reporting of PM2.5 and NH3 point source emissions until June 1,
2004, this burden estimate includes the effort for a State to
update their point source data base in anticipation of this
requirement.
Commenters questioned why EPA did not include an estimate for
industry respondents for PM2.5 reporting, since States may look to
industry to provide PM2>5 information. Another commenter
maintained that it seems inappropriate to include industry
respondents when developing the burden estimates. The EPA will
include an estimate of the burden hours required by industry, as
well as by State and local agencies, to report PM2.5 and NH3 from
point sources in a subsequent revised ICR. States will be
required to commence point source reporting of PM2>5 and NH3 at a
later date as detailed in §51.30.
Finally, several commenters believed that the capital and
operations and maintenance costs were not representative of actual
costs that would be incurred by respondents. The EPA agrees and
we have increased the costs to reflect a higher number of work
stations, and multiplied costs per respondent by an increased
number of respondents. In addition, although not included as a
capital cost, EPA accounted for the labor hours and associated
costs of respondents to convert their reporting systems to CERR-
compatible format, since all agencies' reporting systems are not
presently compatible with EPA's NEI Input format.
The total burden impact of the CERR is estimated to be 84,035
hours per year for State, Territorial and local respondents. It
should be noted that, of this total of 84,035 hours per year,
approximately 34,000 hours per year are associated with start-up
costs that will no longer be incurred after the first three years.
Thus, after three years, the estimated burden becomes about 50,000
hours per year.
We did not include Tribes in our estimate of burden. While
Tribes may report their emissions to us, under the Tribal
Authority Rule they are not required to do so. If the Tribes do
not provide emissions estimates to us, we will estimate their
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emissions for them. Generally, the emissions from tribal lands
are not major and therefore the burden associated with estimating
these emissions is not large.
Burden means the total time, effort, or financial resources
expended by persons to generate, maintain, retain, or disclose or
provide information to or for a Federal agency. This includes the
time needed to review instructions; develop, acquire, install, and
utilize technology and systems for the purposes of collecting,
validating, and verifying information,
processing and maintaining information, and disclosing and
providing information; adjust the existing ways to comply with any
previously applicable instructions and requirements; train
personnel to be able to respond to a collection of information;
search data sources; complete and review the collection of
information; and transmit or otherwise disclose the information.
An Agency may not conduct or sponsor, and a person is not
required to respond to a collection of information unless it
displays a currently valid OMB control number. The OMB control
numbers for EPA's regulations are listed in 40 CFR Part 9 and 48
CFR Chapter 15. The OMB control number for the information
collection requirements in this rule will be listed in an
amendment to [40 CFR part 9 or 48 CFR Chapter 15] in a subsequent
Federal Register document after OMB approves the ICR.
D. Regulatory Flexibility Act (RFA), as Amended by the Small
Business Regulatory Enforcement Fairness Act of 1966 (SBREFA), 5
U.S.C. 601 et sea.
The Regulatory Flexibility Act (RFA), as amended by the Small
Business Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5
USC 601 et. seq., generally requires an agency to prepare a
regulatory flexibility analysis of any rule subject to notice and
comment rulemaking requirements under the Administrative Procedure
Act or any other statute unless the agency certifies that the rule
will not have a significant economic impact on a substantial
number of small entities. Small entities include small
businesses, small organizations, and small governmental
jurisdictions.
For purposes of assessing the impacts of today's rule on small
entities, small entity is defined as: (1) a small business is
defined in the Small Business Administration's (SBA) regulations
at 13 CFR 121.201. SBA defines small business by category of
business using North American Industry Classification System
(NAICS) codes; (2) a small governmental jurisdiction that is a
government of a city, county, town, school district or special
district with a population of less than 50,000; and (3) a small
organization that is any not-for-profit enterprise which is
independently owned and operated and is not dominant in its field.
The EPA has determined that this final rule will not have a
significant economic impact on a substantial number of small
entities. As stated in the preamble under "Who will have to
comply with the CERR requirements?" and in the rule under §51.1,
the rule applies only to State agencies, which do not constitute
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small entities within the meaning of the RFA.
E. E.O. 13045: Children's Health Protection
Executive Order 13045: "Protection of Children from
Environmental Health Risks and Safety Risks" (62FR19885, April 23,
1997) applies to any rule that: (1) is determined to be
"economically significant" as defined under E.O. 12866, and (2)
concerns an environmental health or safety risk that EPA has
reason to believe may have a disproportionate effect on children.
If the regulatory action meets both criteria, the Agency must
evaluate the environmental health or safety effects of the planned
rule on children, and explain why the planned regulation is
preferable to other potentially effective and reasonably feasible
alternatives considered by the Agency.
The EPA interprets E.O. 13045 as applying only to those
regulatory actions that are based on health or safety risks, such
that the analysis required under section 5-501 of the Order has
the potential to influence the regulation. This rule is not
subject to E.O. 13045 because it is based on the need for
information to characterize health and safety risks themselves.
F. The National Technology Transfer and Advancement Act
Section 12(d) of the National Technology Transfer and
Advancement Act of 1995 (NTTAA), Pub L. No. 104-113, § 12(d) (15
U.S.C. 272 note) directs EPA to use voluntary consensus standards
in its regulatory activities unless to do so would be inconsistent
with applicable law or otherwise impractical. Voluntary consensus
standards are technical standards (e.g., materials specifications,
test methods, sampling procedures, and business practices) that
are developed or adopted by voluntary consensus standards bodies.
The NTTAA directs EPA to provide Congress, through OMB,
explanations when the Agency decides not to use available and
applicable voluntary consensus standards.
This rule does not involve technical standards. Therefore,
EPA is not considering the use of any voluntary consensus
standards.
G. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA),
P.L. 104-4, establishes requirements for Federal agencies to
assess the effects of their regulatory actions on State, local,
and tribal governments and the private sector. Under section 202
of the UMRA, EPA generally must prepare a written statement,
including a cost-benefit analysis, for proposed and final rules
with "Federal mandates" that may result in expenditures to State,
local, and tribal governments, in the aggregate, or to the private
sector, of $100 million or more in any one year. Before
promulgating an EPA rule for which a written statement is needed,
section 205 of the UMRA generally requires EPA to identify and
consider a reasonable number of regulatory alternatives and adopt
the least costly, most cost-effective or least burdensome
alternative that achieves the objectives of the rule. The
provisions of section 205 do not apply when they are inconsistent
with applicable law. Moreover, section 205 allows EPA to adopt an
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alternative other than the least costly, most cost-effective or
least burdensome alternative if the Administrator publishes with
the final rule an explanation why that alternative was not
adopted. Before EPA establishes any regulatory requirements that
may significantly or uniquely affect small governments, including
tribal governments, it must have developed under section 203 of
the UMRA a small government agency plan. The plan must provide
for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and
timely input in the development of EPA regulatory proposals with
significant Federal intergovernmental mandates, and informing,
educating, and advising small governments on compliance with the
regulatory requirements.
The EPA has determined that this rule does not contain a
Federal mandate that may result in expenditures of $100 million or
more for State, local, and tribal governments, in the aggregate,
or the private sector in any one year. The additional work
required by this rule takes advantage of information already in
the possession of reporting groups. Using existing data leverages
past work and reduces the burden of this rule. This conclusion is
supported by the analysis done in support of EPA ICR No. 0916.10,
which shows that total costs will be about $2,730,000. The EPA
has also determined that this rule does not apply to small
government entities. As discussed in this preamble under section
"D. Impact on Small Entities", this rule applies only to State
governments. Thus, today's rule is not subject to the
requirements of sections 202, 203 and 205 of the UMRA.
H. Executive Order 13132: Federalism
Executive Order 13132, entitled "Federalism" (64 FR 43255,
August 10, 1999), requires EPA to develop an accountable process
to ensure "meaningful and timely input by State and local
officials in the development of regulatory policies that have
federalism implications." "Policies that have federalism
implications" is defined in the Executive Order to include
regulations that have "substantial direct effects on the States,
on the relationship between the national government and the
States, or on the distribution of power and responsibilities among
the various levels of government."
Under section 6 of Executive Order 13132, EPA may not issue a
regulation that has federalism implications, that imposes
substantial direct compliance costs, and that is not required by
statute, unless the Federal government provides the funds
necessary to pay the direct compliance costs incurred by State and
local governments, or EPA consults with State and local officials
early in the process of developing the proposed regulation. The
EPA also may not issue a regulation that has federalism
implications and that preempts State law, unless the Agency
consults with State and local officials early in the process of
developing the proposed regulation.
If EPA complies by consulting, Executive Order 13132 requires
EPA to provide to the Office of Management and Budget (OMB), in a
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separately identified section of the preamble to the rule, a
federalism summary impact statement (FSIS). The FSIS must include
a description of the extent of EPA's prior consultation with State
and local officials, a summary of the nature of their concerns and
the agency's position supporting the need to issue the regulation,
and a statement of the extent to which the concerns of State and
local officials have been met. Also, when EPA transmits a draft
final rule with federalism implications to OMB for review pursuant
to Executive Order 12866, EPA must include a certification from
the agency's Federalism Official stating that EPA has met the
requirements of Executive Order 13132 in a meaningful and timely
manner.
In the proposed rule (65 FR 33273), EPA proposed to conclude
that this rule did have federalism implications. This was based
on the fact the proposed rule would require States to report their
emissions Statewide and to report PM2.5 and NH3 emissions. It was
also assumed that since such reporting may impose direct costs on
State or local governments, and since the Federal government will
not provide the funds necessary to pay those costs, that the
federalism provisions would apply. The EPA has reconsidered this
position. The federalism provisions are intended to apply to
rules that substantially alter the relationship between the
Federal Government and State governments. This rule in large
measure consolidates pre-existing reporting requirements and the
incremental burden of the new requirements is about $2,133,000
annually. While this rule will impact State governments by
imposing new emission inventory reporting requirements, EPA does
not believe that this causes a substantial change in the
relationship between the national government and the States, or on
the distribution of power and responsibilities among the various
levels of government, as specified in Executive Order 13132.
Thus, the requirements of section 6 of the Executive Order do not
apply to this rule.
I. Executive Order 13175: Consultation and Coordination with
Indian Tribal Governments
Executive Order 13175, entitled "Consultation and
Coordination with Indian Tribal Governments" (65 FR 67249,
November 6, 2000), requires EPA to develop an accountable process
to ensure "meaningful and timely input by tribal officials in the
development of regulatory policies that have tribal implications."
"Policies that have tribal implications" is defined in the
Executive Order to include regulations that have "substantial
direct effects on one or more Indian tribes, on the relationship
between the Federal government and the Indian tribes, or on the
distribution of power and responsibilities between the Federal
government and Indian tribes."
This final rule does not have tribal implications. It will
not have substantial direct effects on tribal governments, on the
relationship between the Federal government and Indian tribes, or
on the distribution of power and responsibilities between the
Federal government and Indian tribes, as specified in Executive
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Order 13175. The Tribal Authority Rule means that Tribes cannot be
required to report their emissions to us. Thus, Executive Order
13175 does not apply to this rule.
J. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
This rule is not a "significant energy action" as defined in
Executive Order 13211, "Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use" (66 FR
28355 (May 22, 2001)) because it is not likely to have a
significant adverse effect on the supply, distribution, or use of
energy. This rule defines the requirements for the reporting of
emission inventories by State and local agencies to EPA. We do
not believe that this rule will effect the supply, production,
availability, cost or use on energy in the United States.
Further, we have concluded that this rule is not likely to have
any adverse energy effects.
K. Congressional Review Act
The Congressional Review Act, 5 U.S.C. 801 et seq., as added
by the Small Business Regulatory Enforcement Fairness Act of 1996,
generally provides that before a rule may take effect, the agency
promulgating the rule must submit a rule report, which includes a
copy of the rule, to each House of the Congress and to the
Comptroller General of the United States. EPA will submit a
report containing this rule and other required information to the
U.S. Senate, the U.S. House of Representatives, and the
Comptroller General of the United States prior to publication of
the rule in the Federal Register. A Major rule cannot take effect
until 60 days after it is published in the Federal Register. This
action is not a "major rule" as defined by 5 U.S.C. 804(2). This
rule will become effective 60 days after it is published in the
Federal Register.
List of Subjects in 40 CFR Part 51
Environmental protection, Administrative practice and procedure,
Air pollution control, Intergovernmental relations, Reporting and
recordkeeping requirements.
Dated: May 23, 2002. Christine Todd Whitman,
Administrator.
For the reasons stated in the preamble, title 40, chapter I, of
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the Code of Federal Regulations is amended as follows:
PART 51 -- [AMENDED]
1. The authority citation for part 51 continues to read as
follows:
Authority: 23 U.S.C. 101; 42 U.S.C. 7401 - 7671q.
2. Part 51 is amended by adding subpart A to read as
follows:
Subpart A - Emission Inventory Reporting Requirements
GENERAL INFORMATION FOR INVENTORY PREPARERS
Sec.
51.1 Who is responsible for actions described in this
subpart?
51.5 What tools are available to help prepare and report
emissions data?
51.10 How does my State report emissions that are required by
the NOX SIP Call?
SPECIFIC REPORTING REQUIREMENTS
51.15 What data does my State need to report to EPA?
51.20 What are the emission thresholds that separate point
and area sources?
51.25 What geographic area must my State's inventory cover?
51.30 When does my State report the data to EPA?
51.35 How can my State equalize the effort for annual
reporting?
51.40 In what form should my State report the data to EPA?
51.45 Where should my State report the data?
Appendix A to Subpart A of Part 51 - Tables and Glossary
Appendix B to Subpart A of Part 51 - [Reserved]
Subpart A - Emission Inventory Reporting Requirements
GENERAL INFORMATION FOR INVENTORY PREPARERS
§51.1 Who is responsible for actions described in this subpart?
State agencies whose geographic coverage include any point,
area, mobile, or biogenic sources must inventory these sources and
report this information to EPA.
§51.5 What tools are available to help prepare and report
emissions data?
We urge your State to use estimation procedures described in
documents from the Emission Inventory Improvement Program (EIIP).
These procedures are standardized and ranked according to relative
uncertainty for each emission estimating technique. Using this
guidance will enable others to use your State's data and evaluate
its quality and consistency with other data.
§51.10 How does my State report emissions that are required by
the NOX SIP Call?
The States and the District of Columbia that are subject to
the NOX SIP Call (§51.121) should report their emissions under the
provisions of §51.122. To avoid confusion, these requirements are
not repeated here.
SPECIFIC REPORTING REQUIREMENTS
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§51.15 What data does my State need to report to EPA?
(a) Pollutants. Report actual emissions of the following
(see Glossary to Appendix A to this subpart for precise
definitions as required):
(1) Required Pollutants:
(i) Sulfur oxides.
(ii) VOC.
(iii) Nitrogen oxides.
(iv) Carbon monoxide.
(v) Lead and lead compounds.
(vi) Primary PM2>5.
(vii) Primary PM10.
(viii) NH3.
(2) Optional Pollutant:
(i) Primary PM.
(b) Sources. Emissions should be reported from the following
sources:
(1) Point.
(2) Area.
(3) Onroad mobile.
(4) Nonroad mobile.
(5) Biogenic.
(c) Supporting information. Report the data elements in
Tables 2a through 2d of Appendix A to this subpart. Depending on
the format you choose to report your State data, additional
information not listed in Tables 2a through 2d will be required.
We may ask you for other data on a voluntary basis to meet special
purposes.
(d) Confidential data. We don't consider the data in Tables
2a through 2d of Appendix A to this subpart confidential, but some
States limit release of this type of data. Any data that you
submit to EPA under this rule will be considered in the public
domain and cannot be treated as confidential. If Federal and
State requirements are inconsistent, consult your EPA Regional
Office for a final reconciliation.
§51.20 What are the emission thresholds that separate point and
area sources?
(a) All anthropogenic stationary sources must be included in
your inventory as either point or area sources.
(b) See Table 1 of Appendix A to this subpart for minimum
reporting thresholds on point sources.
(c) Your State has two alternatives to the point source
reporting thresholds in paragraph (b) of this section:
(1) You may choose to define point sources by the definition
of a major source used under CAA Title V, see 40 CFR 70.2.
(2) If your State has lower emission reporting thresholds for
point sources than paragraph (b) of this section, then you may use
these in reporting your emissions to EPA.
(d) All stationary sources that have actual emissions lower
than the thresholds specified in paragraphs (b) and (c) of this
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section, should be reported as area sources.
§51.25 What geographic area must my State's inventory cover?
Because of the regional nature of these pollutants, your
State's inventory must be statewide, regardless of an area's
attainment status.
§51.30 When does my State report the data to EPA?
Your State is required to report two basic types of emission
inventories to us: Annual Cycle Inventory; and Three-year Cycle
Inventory.
(a) Annual cycle. You are required to report annually data
from Type A (large) point sources. Except as provided in
paragraph (e) of this section, the first annual cycle inventory
will be for the year 2001 and must be submitted to us within 17
months, i.e., by June 1, 2003. Subsequent annual cycle
inventories will be due 17 months following the end of the
reporting year. See Table 2a of Appendix A to this subpart for the
specific data elements to report annually.
(b) Three-year cycle. You are required to report
triennially, data for Type B (all) point sources, area sources and
mobile sources. Except as provided in paragraph (e) of this
section, the first three-year cycle inventory will be for the year
2002 and must be submitted to us within 17 months, i.e., by June
1, 2004. Subsequent three-year cycle inventories will be due 17
months following the end of the reporting year. See Tables 2a, 2b
and 2c of Appendix A to this subpart for the specific data
elements that must be reported triennially.
(c) NOXSIP call. There are specific annual and three-year
reporting requirements for States subject to the NOX SIP call.
See §51.122 for these requirements.
(d) Biogenic emissions. Biogenic emissions are part of your
3-year cycle inventory. Your State must establish an initial
baseline for biogenic emissions that is due as specified under
paragraph (b) of this section. Your State need not submit more
biogenic data unless land use characteristics or the methods for
estimating emissions change substantially. If either of these
changes, your State must report the biogenic emission data
elements shown in Table 2d of Appendix A to this subpart. Report
these data elements 17 months after the end of the reporting year.
(e) Point Sources. States must commence reporting point
source emissions of PM2.5 and NH3 on June 1, 2004 unless that date
is less than 60 days after EPA publishes an approved Information
Collection Request (ICR) addressing this section. If EPA fails to
publish an approved ICR 60 days in advance of June 1, 2004, States
must commence reporting point source emissions of PM2.5 and NH3 on
the next annual or triennial reporting date (as appropriate) that
is at least 60 days after EPA publishes an approved ICR addressing
this subsection of the rule.
§51.35 How can my State equalize the effort for annual reporting?
(a) Compiling a 3-year cycle inventory means much more effort
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every three years. As an option, your State may ease this
workload spike by using the following approach:
(1) Annually collect and report data for all Type A (large) point
sources (This is required for all Type A point sources).
(2) Annually collect data for one-third of your smaller point
sources (Type B point sources minus Type A (large) point sources).
Collect data for a different third of these sources each year so
that data has been collected for all of the smaller point sources
by the end of each three-year cycle. You may report these data to
EPA annually, or as an option you may save three years of data and
then report all of the smaller point sources on the three-year
cycle due date.
(3) Annually collect data for one-third of the area, nonroad
mobile, onroad mobile and, if required, biogenic sources. You may
report these data to EPA annually, or as an option you may save
three years of data and then report all of these data on the
three-year cycle due date.
(b) For the sources described in paragraph (a) of this
section, your State will therefore have data from three successive
years at any given time, rather than from the single year in which
it is compiled.
(c) If your State chooses the method of inventorying one-
third of your smaller point sources and 3-year cycle area, nonroad
mobile, onroad mobile sources each year, your State must compile
each year of the three-year period identically. For example, if a
process hasn't changed for a source category or individual plant,
your State must use the same emission factors to calculate
emissions for each year of the three-year period. If your State
has revised emission factors during the three years for a process
that hasn't changed, resubmit previous year's data using the
revised factor. If your State uses models to estimate emissions,
you must make sure that the model is the same for all three years.
(d) If your State chooses the method of inventorying one-
third of your smaller point sources and 3-year cycle area, nonroad
mobile, onroad mobile sources each year and reporting them on the
3-year cycle due date, the first required date for you to report
on all such sources will be June 1, 2004 as specified in §51.30.
You can satisfy the 2004 reporting requirement by either: start
inventorying one third of your sources in 2000; or doing a one-
time complete 3-year cycle inventory for 2002, then changing to
the option of inventorying one third of your sources for
subsequent years.
(e) If your State needs a new reference year emission
inventory for a selected pollutant, your State can't use these
optional reporting frequencies for the new reference year.
(f) If your State is a NOX SIP call State, you can't use
these optional reporting frequencies for NOX SIP call reporting.
§51.40 In what form should my State report the data to EPA?
You must report your emission inventory data to us in
electronic form. We support specific electronic data reporting
formats and you are required to report your data in a format
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consistent with these. Because electronic reporting technology
continually changes, contact the Emission Factor and Inventory
Group (EFIG) for the latest specific formats. You can find
information on the current formats at the following Internet
address: http://www.epa.gov/ttn/chief You may also call our Info
CHIEF help desk at (919)541-1000 or email to info.chief@epa.gov.
§51.45 Where should my State report the data?
(a) Your State submits or reports data by providing it
directly to EPA.
(b) The latest information on data reporting procedures is
available at the following Internet address:
http://www.epa.gov/ttn/chief You may also call our Info CHIEF
help desk at (919)541-1000 or email to info.chief@epa.gov.
Appendix A to Subpart A of Part 51 - Tables and Glossary
Table 1. Minimum Point Source Reporting Thresholds by
Pollutant (tpy1)
Pollutant
l.SOx
2.VOC
3.VOC
4.VOC
5.VOC
6.NOX
7. CO
8. CO
9.Pb
10.PM1D
ll.PM10
1 2 . PM2 5
13.NH3
Annual Cycle
(Type A Sources)
>2500
>250
>2500
>2500
>250
>250
>250
Three-year Cycle
Type B Sources2
>100
>100
>100
>1000
>5
>100
>100
>100
NAA3
>100
03 (moderate) >100
03 (serious)> 50
03 (severe)> 25
03 (extreme) > 10
>100
03 (all areas) >100
CO (all areas) >100
>5
PM10 (moderate) >100
PM10 (serious)>70
>100
>100
Ltpy = tons per year of actual emissions.
2Type A sources are a subset of the Type B sources and are the larger emitting sources by pollutant.
3NAA = Nonattainment Area. Special point source reporting thresholds apply for certain pollutants by type of
nonattainment area. The pollutants by nonattainment area are: Ozone: VOC, NOX/ CO; CO: CO; PM10: PM10
Table 2a. Data Elements that States Must Report for Point Sources
Data Elements
1 . Inventory year
2 . Inventory start date
3. Inventory end date
4 . Inventory type
Annual
(Type A
Sources)
•
•
•
•
Every 3 Years
(Type B Sources
and NAAs)
•
•
•
•
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5. State FIPS code
6. County FIPS code
7. Facility ID code
8. Point ID code
9. Process ID code
10. Stack ID code
11. Site name
12. Physical address
13. SCC or PCC
14. Heat content (fuel)
(annual average)
15. Ash content
(fuel) (annual average)
16. Sulfur content
(fuel) (annual average)
17. Pollutant code
18 .Activity/throughput
(annual)
19 .Activity/ throughput
(daily)
20. Work weekday emissions
21. Annual emissions
22. Emission factor
23. Winter throughput (%)
24. Spring throughput (%)
2 5 . Summer throughput ( % )
26. Fall throughput (%)
27.Hr/day in operation
28. Start time (hour)
29.Day/wk in operation
30.Wk/yr in operation
31.X stack coordinate
(latitude)
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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32. Y stack coordinate
(longitude)
33. Stack Height
34. Stack diameter
35. Exit gas temperature
36. Exit gas velocity
37. Exit gas flow rate
38.SIC/NAICS
39. Design capacity
40. Maximum namemplate
capacity
41. Primary control eff (%)
42. Secondary control eff
1 9- \
( 'o)
43. Control device type
44. Rule effectiveness (%)
•
•
•
•
•
•
•
•
•
•
•
•
•
Table 2b. Data Elements that States Must Report for Area and
Nonroad Mobile Sources
Data Elements
1 . Inventory year
2 . Inventory start date
3. Inventory end date
4 . Inventory type
5. State FIPS code
6. County FIPS code
7. SCC or PCC
8. Emission factor
9 .Activity/throughput level (annual)
10. Total capture/control efficiency
1 9- \
( 'o)
11. Rule effectiveness (%)
12. Rule penetration (%)
Every 3 Years
•
•
•
•
•
•
•
•
•
•
•
•
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13. Pollutant code
14 . Summer/winter work weekday
emissions
15. Annual emissions
16. Winter throughput (%)
17. Spring throughput (%)
18. Summer throughput (%)
19. Fall throughput (%)
20.Hrs/day in operation
21.Days/wk in operation
22.Wks/yr in operation
•
•
•
•
•
•
•
•
•
•
Table 2c. Data Elements that States Must Report for Onroad
Mobile Sources
Data Elements
1 . Inventory year
2 . Inventory start date
3. Inventory end date
4 . Inventory type
5. State FIPS code
6. County FIPS code
7. SCC or PCC
8. Emission factor
9. Activity (VMT by Roadway Class)
10. Pollutant code
11 . Summer/winter work weekday
emissions
12. Annual emissions
Every 3 Years
•
•
•
•
•
•
•
•
•
•
•
•
Table 2d. Data Elements that States Must Report for Biogenic Sources
Data Elements
Every 3
Years
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1 . Inventory year
2 . Inventory start dat
3. Inventory end date
4 . Inventory type
5. State FIPS code
6. County FIPS code
7. SCC or PCC
8. Pollutant code
9 . Summer/winter work
emissions
10. Annual emissions
:e
weekday
•^
*S
*S
*S
+ S
+ S
*S
*S
*S
*S
GLOSSARY
Activity rate/throughput (annual) - A measurable factor or parameter that
relates directly or indirectly to the emissions of an air pollution
source. Depending on the type of source category, activity information
may refer to the amount of fuel combusted, raw material processed,
product manufactured, or material handled or processed. It may also
refer to population, employment, number of units, or miles traveled.
Activity information is typically the value that is multiplied against an
emission factor to generate an emissions estimate.
Activity rate/throughput (daily) - The beginning and ending dates and
times that define the emissions period used to estimate the daily
activity rate/throughput.
Annual emissions - Actual emissions for a plant, point, or process -
measured or calculated that represent a calendar year.
Area sources - Area sources collectively represent individual sources
that have not been inventoried as specific point, mobile, or biogenic
sources. These individual sources treated collectively as area sources
are typically too small, numerous, or difficult to inventory using the
methods for the other classes of sources.
Ash content - Inert residual portion of a fuel.
Biogenic sources - Biogenic emissions are all pollutants emitted from
non-anthropogenic sources. Example sources include trees and vegetation,
oil and gas seeps, and microbial activity.
Control device type - The name of the type of control device (e.g., wet
scrubber, flaring, or process change).
County FIPS Code - Federal Information Placement System (FIPS)is the
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system of unique numeric codes the government developed to identify
States, counties and parishes for the entire United States, Puerto Rico,
and Guam.
Day/wk in operations - Days per week that the emitting process operates -
average over the inventory period.
Design capacity - A measure of the size of a point source, based on the
reported maximum continuous capacity of the unit.
Emission factor - Ratio relating emissions of a specific pollutant to an
activity or material throughput level.
Exit gas flow rate - Numeric value of stack gas's flow rate.
Exit gas temperature - Numeric value of an exit gas stream's temperature.
Exit gas velocity - Numeric value of an exit gas stream's velocity.
Facility ID code - Unique code for a plant or facility, containing one or
more pollutant-emitting sources. This is the data element in Appendix A,
Table 2a, that is defined elsewhere in this glossary as a "point source".
Fall throughput(%) - Part of the throughput for the three Fall months
(September, October, November). This expresses part of the annual
activity information based on four seasons - typically spring, summer,
fall, and winter. It can be a percentage of the annual activity (e.g.,
production in summer is 40% of the year's production) or units of the
activity (e.g., out of 600 units produced, spring = 150 units, summer =
250 units, fall = 150 units, and winter = 50 units).
Heat content - The amount of thermal heat energy in a solid, liquid, or
gaseous fuel. Fuel heat content is typically expressed in units of
Btu/lb of fuel, Btu/gal of fuel, joules/kg of fuel, etc.
Hr/day in operations - Hours per day that the emitting process operates -
average over the inventory period.
Inventory end date - Last day of the inventory period.
Inventory start date - First day of the inventory period.
Inventory type - Type of inventory represented by data (e.g., point, 3-
year cycle, daily).
Inventory year - The calendar year for which you calculated emissions
estimates.
Lead (Pb)- As defined in 40 CFR 50.12, lead should be reported as
elemental lead and its compounds.
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Maximum nameplate capacity - A measure of a unit's size that the
manufacturer puts on the unit's nameplate.
Mobile source - A motor vehicle, nonroad engine or nonroad vehicle.
• A "motor vehicle" is any self-propelled vehicle used to carry people
or property on a street or highway.
• A "nonroad engine" is an internal combustion engine (including fuel
system) that is not used in a motor vehicle or vehicle only used for
competition, or that is not affected by sections 111 or 202 of the
CAA.
• A "nonroad vehicle" is a vehicle that is run by a nonroad engine and
that is not a motor vehicle or a vehicle only used for competition.
PM (Particulate Matter) - Particulate matter is a criteria air pollutant.
For the purpose of this subpart, the following definitions apply:
(1) Primary PM: Particles that enter the atmosphere as a direct
emission from a stack or an open source. It is comprised of two
components: Filterable PM and Condensible PM. (As specified in
§51.15 (a)(2), these two PM components are the components measured by
a stack sampling train such as EPA Method 5 and have no upper particle
size limit.)
(2) Filterable PM: Particles that are directly emitted by a source as
a solid or liquid at stack or release conditions and captured on the
filter of a stack test train.
(3) Condensible PM: Material that is vapor phase at stack conditions,
but which condenses and/or reacts upon cooling and dilution in the
ambient air to form solid or liquid PM immediately after discharge
from the stack.
(4) Secondary PM: Particles that form through chemical reactions in
the ambient air well after dilution and condensation have occurred.
Secondary PM is usually formed at some distance downwind from the
source. Secondary PM should NOT be reported in the emission inventory
and is NOT covered by this subpart.
(5) Primary PM2 5: Also PM2.5 (or Filterable PM2.5 and Condensible PM
individually. Note that all Condensible PM is assumed to be in the
PM2>5 size fraction) - Particulate matter with an aerodynamic diameter
equal to or less than 2.5 micrometers.
(6) Primary PM10: Also PM10 (or Filterable PM10 and Condensible PM
individually) - Particulate matter with an aerodynamic diameter equal
to or less than 10 micrometers.
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PCC - Process classification code. A process-level code that describes the
equipment or operation which is emitting pollutants. This code is being
considered as a replacement for the SCC.
Physical address - Street address of a facility. This is the address of
the location where the emissions occur; not, for example, the corporate
headquarters .
Point ID code - Unique code for the point of generation of emissions,
typically a physical piece of equipment.
Point source - Point sources are large, stationary (non-mobile),
identifiable sources of emissions that release pollutants into the
atmosphere. As used in this rule, a point source is defined as a facility
that annually emits more than a "threshold" value as defined under §51.20.
Pollutant code - A unique code for each reported pollutant assigned in the
Emission Inventory Improvement Program (EIIP) Data Model. The EIIP model
was developed to promote consistency in organizations sharing emissions
data. The model uses character names for criteria pollutants and Chemical
Abstracts Service (CAS) numbers for all other pollutants. You may be using
SAROAD codes for pollutants, but you should be able to map them to the
pollutant codes in the EIIP Data Model.
Process ID code - Unique code for the process generating the emissions,
typically a description of a process.
Roadway class - A classification system developed by the Federal Highway
Administration that defines all public roadways as to type. Currently
there are four roadway types: 1) freeway, 2) freeway ramp, 3)
arterial/collector and 4) local.
Rule effectiveness (RE) - How well a regulatory program achieves all
possible emission reductions. This rating reflects the assumption that
controls typically aren't 100 percent effective because of equipment
downtime, upsets, decreases in control efficiencies, and other deficiencies
in emission estimates. RE adjusts the control efficiency.
Rule penetration - The percentage of an area source category covered by an
applicable regulation.
SCC - Source classification code. A process-level code that describes the
equipment and/or operation which is emitting pollutants.
Seasonal activity rate/throughput - A measurable factor or parameter that
relates directly or indirectly to the pollutant season emissions of an air
pollution source. Depending on the type of source category, activity
information may refer to the amount of fuel combusted, raw material
processed, product manufactured, or material handled or processed. It may
also refer to population, employment, number of units, or miles traveled.
Activity information is typically the value that is multiplied against an
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emission factor to generate an emissions estimate.
Seasonal fuel heat content - The amount of thermal heat energy in a solid,
liquid, or gaseous fuel used during the pollutant season. Fuel heat
content is typically expressed in units of Btu/lb of fuel, Btu/gal of fuel,
joules/kg of fuel, etc.
Secondary control eff (%) - The emission reduction efficiency of a
secondary control device. Control efficiency is usually expressed as a
percentage or in tenths.
SIC/NAICS - Standard Industrial Classification code. NAICS (North American
Industry Classification System) codes will replace SIC codes. U.S.
Department of Commerce's code for businesses by products or services.
Site name - The name of the facility.
Spring throughput(%) - Part of throughput or activity for the three spring
months (March, April, May). See the definition of Fall Throughput.
Stack diameter - A stack's inner physical diameter.
Stack height - A stack's physical height above the surrounding terrain.
Stack ID code - Unique code for the point where emissions from one or more
processes release into the atmosphere.
Start time (hour) - Start time (if available) that you used to calculate
the emissions estimates.
State FIPS Code - Federal Information Placement System (FIPS)is the system
of unique numeric codes the government developed to identify States,
counties and parishes for the entire United States, Puerto Rico, and Guam.
Sulfur content - Sulfur content of a fuel, usually expressed as percent by
weight.
Summer throughput(%) - Part of throughput or activity for the three summer
months (June, July, August). See the definition of Fall Throughput.
Summer/winter work weekday emissions - Average day's emissions for a
typical day. Ozone daily emissions = summer work weekday; CO and PM daily
emissions = winter work weekday.
Total capture/control efficiency - The emission reduction efficiency of a
primary control device, which shows the amount controls or material changes
reduce a particular pollutant from a process' emissions. Control
efficiency is usually expressed as a percentage or in tenths.
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Type A source - Large point sources with actual annual emissions greater
than or equal to any of the emission thresholds listed in Table 1 for Type
A sources.
Type B source - Point sources with actual annual emissions during any year
of the three year cycle greater than or equal to any of the emission
thresholds listed in Table 1 for Type B sources. Type B sources include
all Type A sources.
VMT by Roadway Class - Vehicle miles traveled (VMT) expresses vehicle
activity and is used with emission factors. The emission factors are
usually expressed in terms of grams per mile of travel. Because VMT
doesn't correlate directly to emissions that occur while the vehicle isn't
moving, these nonmoving emissions are incorporated into the emission
factors in EPA's MOBILE Model.
VOC - Volatile Organic Compounds. The EPA's regulatory definition of VOC
is in 40 CFR § 51.100.
Winter throughput (%) - Part of throughput or activity for the three winter
months (December, January, February, all from the same year, e.g., Winter
2000 = January 2000 + February, 2000 + December 2000). See the definition
of Fall Throughput.
Wk/yr in operation - Weeks per year that the emitting process operates.
Work Weekday - Any day of the week except Saturday or Sunday.
X stack coordinate (latitude) - An object's north-south geographical
coordinate.
Y stack coordinate (longitude) - An object's east-west geographical
coordinate.
Appendix B to Subpart A of Part 51 - [Reserved]
Subpart Q - [Amended]
3. Section 51.321 is revised to read as follows:
§51.321 Annual source emissions and State action report.
The State agency shall report to the Administrator (through the
appropriate Regional Office) information as specified in §§51.322 through
51.326.
4. Section 51.322 is revised to read as follows:
§51.322 Sources subject to emissions reporting.
The requirements for reporting emissions data under the plan are in
subpart A of this part 51.
5. Section 51.323 is revised to read as follows:
§51.323 Reportable emissions data and information.
The requirements for reportable emissions data and information under
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the plan are in subpart A of this part 51
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APPENDIX B
REVISED RULE EFFECTIVENESS GUIDANCE
Introduction
In the Spring of 2004, a workgroup consisting of emissions inventory staff from state, local and EPA offices
convened to review existing rule effectiveness (RE) guidance, and if possible develop a consensus recommendation
for improvements to this guidance. Initial discussions among workgroup members revealed agreement that making
adjustments to inventory estimates to account for rule effectiveness was appropriate, but that the existing guidance
was not meeting the inventory community's needs. There was general agreement that adjustments to inventory
estimates to account for RE were not occurring in a consistent manner across states and EPA regions.
Through a series of conference calls, the workgroup developed recommendations to revise EPA's existing
rule effectiveness guidance. This document presents the revised guidance, and it consists of this introductory text
and accompanying frequently asked questions (FAQ) section, attachment 1 containing a questionnaire for point
sources, and attachment 2 which contains a shorter questionnaire for non-point (formerly called area) sources.
Perhaps of most significance, the revised guidance removes the previous recommendation for use of an across the
board 80% default value for RE. In its place, this new guidance provides inventory preparers with a listing of the
factors that are most likely to affect RE, and ranks these factors in a priority order. Likely responses to evaluation of
these factors were then grouped into RE ranges, such that more positive responses to a number of the factors will lead
towards selection of a higher RE value, whereas more negative responses will direct one to select an RE value from a
lower range.
For example, if a state has a regulation covering autobody shops, and inspected more than 25% of the sources
in a given year and found that 90% or more were in compliance, and took enforcement action against non-compliant
sources, the area source questionnaire would direct the state to select an RE value from the highest range, which is
from 86 to 100%. It would be up to the state agency to select the exact value to use. Conversely, if fewer than 15%
of the sources had been inspected, and violations were found about half the time, and the state was having difficulty
processing enforcement actions against violators, an RE value from the lowest area source range, which is 70% or
less, should be chosen.
Please note that this rule effectiveness guidance only applies to stationary point and non-point sources; it
does not apply to mobile sources. EPA policy remains that in the development of emission inventories, RE must be
considered as part of the emission estimation calculation for controlled sources, although there are some exceptions
to this as noted in the FAQ part of this document. Importantly, a state or local agency's rationale for the RE
value chosen must be documented within the emissions inventory.
Use of Facility Specific Information
First and foremost, an agency responsible for emissions inventory preparation should attempt to obtain
facility specific data from as many sources as possible, and use the collected information to make a refined source or
source category RE determination. A review of the factors that influence RE as outlined in the two attachments
should provide a state or local agency with the necessary information on the types of data to collect. States are free
to select their own set of data to collect from their sources in order to make source or source category specific RE
adjustments. However, if such data deviates substantially from the RE factors identified in the two attachments to
this document, the agency should discuss its proposed method with the appropriate EPA regional office. EPA's
December 21, 1992 document, "Revised Rule Effective National "Protocol" contains useful information on crafting a
refined estimate of RE via conduct of a local evaluation. The document is available on EPA's CHIEF website:
http://www.epa.gov/ttn/chief/.
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Use of RE Analysis Performed by Others
If facility specific information can't be obtained, it is possible that information collected by other state or
local agencies for similar sources in their states may be of use. We are in the process of collecting information from
rule effectiveness evaluation studies conducted in the past and assembling this information and all of the other
documents either produced or relied upon by the RE workgroup. When this information is assembled, it will be
posted on the CHIEF website mentioned above. Studies done by other agencies on the same or similar source
categories may shed light on what type of RE adjustment to use if both agency's regulations and general approach to
enforcement are reasonably comparable.
Selection Based on Factors that Influence RE
It is unlikely that all state and local agencies will be able to collect sufficient information from all of their
stationary sources from which refined RE adjustments can be made. Additionally, no suitable matching studies may
exist from which a rule effectiveness value can be obtained. In such situations, the selection of an RE value becomes
subjective. In an effort to minimize this subjectivity, EPA recommends that state and local agencies choose a RE
level from within the 5 point source ranges shown in attachment 1, or from within the 3 non-point source ranges
shown in attachment 2. The point source ranges are narrower and the factors are described in more detail than the
non-point source ranges and factors because the RE workgroup felt that state and local agencies generally have more
information, and conduct more inspections on facilities within the point source sector.
It is important to note that it is unlikely the source or source category you are evaluating will meet all of the
criteria within any one range. Therefore, select the range which best describes the source or source category
being considered; choose the range that provides the best fit.
The five point source RE ranges are:
94 to 100%;
87 to 93%;
81 to 86%;
70 to 80%;
less than 70%.
The three non-point source RE ranges are:
86 to 100%;
71 to 85%;
less than 70%.
State and local agencies should select an RE value by reviewing the factors for each range as listed in
attachment 1 and 2, and selecting a RE value from within the range that represents the best fit. Within each range,
the factors are listed by order of importance as determined by the workgroup that developed this guidance. Three
tiers are shown within each range; the most important factors that influence rule effectiveness, other important
factors, and other factors which deserve consideration but which weren't regarded as highly as those within the first
two tiers. The factors are listed by order of importance within each tier as determined by the workgroup.
Although use of these ranges offers much more flexibility to states and local agencies in determining rule
effectiveness adjustments compared to the previous guidance, which in essence recommended an across the board use
of an 80% adjustment, variability across states and EPA regions will still exist. It is hoped that creation of these
ranges will reduce that variability. EPA encourages states to try to use source specific data to develop refined RE
estimates to the maximum extent possible rather than rely on these ranges.
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Frequently Asked Questions
1. What does the term "rule effectiveness" mean?
Rule effectiveness (RE) is a term that describes a method to account for the reality that not all facilities
covered by a rule are in compliance with the rule 100% of the time. Additionally, RE accounts for the fact that
control equipment does not always operate at it's assumed control efficiency.
2. How do I make an adjustment for RE when making an emissions estimate?
To adjust an emission unit's emissions for RE, add a percentage RE term to the normal equation used to
estimate the controlled source's emissions. The RE term is used to adjust, in effect lower, the control efficiency. For
example, consider an emission unit with uncontrolled emissions of 150 tpy that operates a piece of control equipment
with a stated control efficiency of 80%. This unit would have it's emissions calculated as follows if the control
equipment is always assumed to be fully operational, and it is assumed the source always operates it:
Uncontrolled Emissions * (1 - Control Efficiency) = Controlled Emissions
150 * (1 - 0.8) = 30 tpy
However, if the agency feels that a review of the factors that influence rule effectiveness indicates that an RE
adjustment of 90% should be made, the equation and resulting emissions are changed as follows:
Uncontrolled Emissions * (1 - (Control Efficiency)*(RE)) = Controlled Emissions
150 * (1 - (0.8*0.9)) = 42 tpy
3. Does this guidance apply to all inventories a state or local agency prepares?
This guidance was developed specifically for use by states required to prepare emission inventories in support of
development of SIPs for the 8-hour ozone and PM2.5 standards. However, the principles put forth here have
relevance to most, if not all types of inventories, and EPA recommends that agencies consider applying it in
development of inventories for other criteria or hazardous air pollutants.
4. Do all emission inventory estimates have to be adjusted to account for RE?
Not all inventory estimates need to be adjusted for RE, only those where a control device or control technique is
used. Furthermore, not all emission estimates involving use of a control device or technique need to be adjusted to
account for RE. In some instances, a state or local agency may feel that the control device or technique has sufficient
safeguards and/or monitoring requirements to account for any control device equipment failure. For example, a state
or local agency may conclude that a control device that operates in conjunction with a continuous emissions monitor,
or is equipped with an automatic shutdown device, may provide a sufficient level of assurance that intended emission
reductions will be achieved, and therefore an adjustment for rule effectiveness is not necessary. Another example
would be in instances where a direct determination of emissions, such as via amass balance calculation, can be made.
5. Does the term "actual emissions" mean an emission estimate that has been adjusted for RE, or an
emission estimate as reported by a source?
Ideally, state and local agencies will work with each source to determine what the best estimate of the
source's emissions are, and that estimate will include any adjustments made to account for rule effectiveness. Thus,
the term "actual emissions" should include an adjustment for rule effectiveness. Some agencies prefer to adjust a
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source's reported emissions for rule effectiveness themselves, and use the "adjusted" emission estimate within their
inventory. In most such cases, the agency would maintain two emission estimates for the same source; one as
reported by the source and another as adjusted by the agency to account for rule effectiveness. The latter estimate
would be the source's actual emissions. Note that this guidance is intended for use in the development of emission
inventories; it is up to each agency to decide if RE adjustment are appropriate for use in other air programs, such as
in permitting programs.
6. Should capture efficiency be considered when determining RE adjustments?
Capture efficiency should be considered when making RE determinations, as defects in the operation of
equipment designed to capture emissions and route them through a control device can result in a substantial increase
in emissions. Emission units that are dependent upon the operation of both capture and control device equipment
should generally receive lower RE adjustments than units equipped with only control devices.
7. Using RE to adjust emissions for highly controlled sources can greatly increase a source's
emissions. Should RE be used in such circumstances?
Malfunction of control equipment that is expected to operate at very high control efficiencies will
substantially increase emissions. An emitting unit whose uncontrolled daily emissions are 10 tons per day equipped
with a control device expected to achieve a 99% control efficiency should only emit 200 Ibs per day. Clearly,
malfunction of the control device can lead to a tremendous increase in emissions. Similarly, application of a rule
effectiveness adjustment will also have a large impact on emissions. States should carefully review the reliability and
past performance history of emission units equipped with control devices expected to achieve very high control
efficiencies to determine an appropriate RE level. Chapter 12 of the Emission Inventory Improvement Program's
point source guidance contains a good description of this phenomenon. That document is available on the internet at:
http://www.epa.gov/ttn/chief/eiip/.
8. Should emissions that occur during start-up, shut-down, upsets, and malfunctions be included in a
facilities emission estimate?
Emissions that occur under all modes of operation need to be included in a facilities emission estimate. State
and local agencies can attempt to estimate emissions from start-up, shut-down, upsets and malfunctions using
whatever techniques they believe will produce the most accurate result. Ideally, emission estimates for these types of
non-normal operating conditions will be obtained using facility specific information. Alternatively, and less
preferably, they can be accounted for using the rule effectiveness adjustment procedures outlined in this guidance.
Some states, for example the South Carolina Bureau of Air Quality, currently collect such information as part
of their annual emissions reporting process. A copy of South Carolina's data collection form is available on the RE
website previously mentioned in this document.
9. What about EPA's existing guidance for the vapor recovery (stage 2) systems; does this guidance
replace that?
Since EPA has collected a considerable amount of data on this source category pertaining to the relationship
between inspection frequency and exemption criteria, and related that to the anticipated level of control, the existing
guidance for vapor recovery systems remains in place. The document containing this guidance is: "Technical
Guidance - Stage II Vapor Recovery Systems for Control of Vehicle Refueling Emissions at Gasoline Dispensing
Facilities" EPA-450/3-91-022a. It can be found on the internet at: http://www.epa.gov/ttn/atw/gasdist/gasdispg.html
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10. How can I calculate SIP credit for emission reductions achieved via improvements to rule
effectiveness?
Such credit will need to be determined on a case by case basis. EPA's older guidance material may be used
as a point of reference, but pursuant to the EPA guidance, "Ozone Nonattainment Planning: Decentralization of Rule
Effectiveness Policy; April 27, 1995", other approaches can also be used. EPA's older guidance is available at the
RE web-site mentioned above, in the documents entitled, "Rule Effectiveness Guidance: Integration of Inventory,
Compliance, and Assessment Applications; EPA-452/4/94-001, January, 1994, " "Transmittal of Rule Effectiveness
Protocol for 1996 Demonstration; December 22, 1994", and "Stationary Source Compliance Division Rule
Effectiveness National Protocol; December 21, 1992".
11. Is this guidance applicable to emission inventories developed in support of the 8-hour ozone or
PM 2.5 NAAQS?
Given the large number of stationary point and area source categories contained within an emission
inventory, it is not EPA's expectation that state and local agencies will immediately implement this revised rule
effectiveness guidance for all sources and source categories. However, we have had a longstanding requirement that
inventories developed to support ozone SIPs consider and account for rule effectiveness. Accordingly, inventories
submitted to meet requirements of the 8-hour ozone standard should at a minimum comply with EPA's prior rule
effectiveness guidance. Additionally, EPA encourages all state and local agencies to begin using the guidance within
this policy as soon as possible, as we believe it will lead to higher quality emission estimates for controlled sources.
12. Is there a quick way to research the compliance history of a source?
The best way to obtain information on the compliance history of a source is to speak with the compliance &
enforcement staff at your agency that are most familiar with the site. Alternatively, you could use EPA databases that
store compliance information. For example, EPA's OTIS database could be used to obtain a quick overview of a
source's compliance history. The following is a description of the OTIS database from EPA's website:
"The OnlineTracking Information System (OTIS) is a collection of search engines enables EPA staff,
state/local/tribal governments, and federal agencies to access a wide range of data relating to enforcement and
compliance. OTIS is a web application that sends queries to the Integrated Data for Enforcement Analysis (IDEA)
system. Only State and Federal agencies have access to the OTIS data system. IDEA copies many EPA and non-EPA
databases monthly, and organizes the information to facilitate cross-database analysis. OTIS can be used for many
functions, including planning, targeting, analysis, data quality review, and pre-inspection review. OTIS was
launched for internal Agency use in November 1999. In addition to performing data base analysis, OTIS has three
other additional benefits:
• helps the Regions and States to identify and clean up data errors;
• provides report information on a cross media basis, leading to improved integration and targeting;
• provides the basis for proposed public access site for enforcement and compliance data.
For additional information please contact Rebecca Kane at kane.rebecca@epa.govwhich"
The ECHO database can be accessed at: http://www.epa.gov/echo/index.html.
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Attachment 1: Point Source Rule Effectiveness Ranges
Range 1: 94 to 100%
Most important factors:
• Monitoring: Source specific monitoring used for compliance purposes, and monitoring records filed with
regulatory agency at least every 4 months;
• Compliance history: the facility has been in compliance for the past eight quarters.
Other important factors:
• Type of inspection: Inspections involve compliance test methods with a high degree of accuracy, such as
stack testing or other types of precise emissions measurement;
• Operation & Maintenance: Control equipment operators follow and sign daily O&M instructions;
• Unannounced inspections routinely conducted;
• Agency has the authority to impose punitive measures, including monetary fines, towards violators such as in
delegated Title V Operating Permit programs.
Other factors:
• Source subject to Title V or other type of compliance certification;
• Source(s) are inspected once every 2 years or more frequently;
• Agency has sufficient resources to implement EPA's 12/22/98 HPV policy;
• Control equipment operators complete a formal training program on use of the equipment, and such program
is kept up to date and has been reviewed by the regulatory agency;
• Media publicity of enforcement actions;
• Regulatory workshops are available annually, and/or the implementing agency mails regulatory information
packages each year;
• Inspectors must undergo 2 weeks of comprehensive basic training, and 1 to 2 weeks of source specific
training, and such training is updated each year;
• Specific guidelines and schedule for testing and test methods exist;
• Follow-up inspections always or almost always done (90 % of the time or more).
Range 2: 87 to 93%
Most important factors:
• Monitoring: Source specific monitoring used as an indicator of compliance, and monitoring records filed
with regulatory agency every 6 to 9 months;
• Compliance history: the facility is believed to have been in compliance for the past eight quarters, although
inspection frequency is such that this can't be positively confirmed.
Other important factors:
Type of inspection: Inspections involve detailed review of process parameters & inspection of control
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equipment;
• Operation & Maintenance: Control equipment operators follow daily O&M instructions;
• Unannounced inspections sometimes done;
• Agency has the authority to impose punitive measures, including monetary fines, towards violators such as in
delegated Title V Operating Permit programs;
Other factors:
• Source subject to Title V or other type of compliance certification;
• Source(s) inspected every 3 years or more frequently;
• Agency's resources allow it to implement EPA's 12/22/98 HPV policy in most instances;
• Control equipment operators complete formal training program, and such program is kept up to date and
available for review by the regulatory agency upon request;
• Media publicity of enforcement actions;
• Regulatory workshop are available every 1 -2 years, and/or the implementing agency mails regulatory
information packages every 1-2 years;
• Inspectors must undergo 1 to 2 weeks of basic training and 1 week of source specific training, and such
training is updated every 1-2 years;
• Specific guidelines on testing and test methods exist, but no schedule for testing.
• Follow-up inspections usually done (approximately 75% of the time).
Range 3: 81 to 86%
Most important factors:
• Monitoring: Source specific monitoring used as an indicator of compliance, and monitoring records filed
with regulatory agency each year;
• Compliance history: On schedule; the facility is meeting its compliance schedule.
Other important factors:
Type of inspection: Inspections involve review of process and inspection of control equipment;
Operation & Maintenance: Control equipment operators follow daily or weekly O&M instructions;
Unannounced inspections done, but infrequently;
Agency has the authority to impose punitive measures, including monetary fines, towards violators such as in
delegated Title V Operating Permit programs.
Other factors
Source not subject to any type of compliance certification;
Source(s) inspected every 5 years or more frequently;
Agency's resources allow it to implement EPA's 12/22/98 HPV policy in most instances;
Control equipment operators complete some amount of formal training;
Media publicity of enforcement actions;
Regulatory workshop are available every 2-3 years, and/or the implementing agency mails regulatory
information packages once every 2-3 years;
Inspectors must undergo 1 to 2 weeks of basic training and 3 to 5 days of source specific training, and such
training is updated every 1-2 years;
Specific guidelines on testing and test methods exist, but no schedule for testing.
Follow-up inspections sometimes done (approximately 50% of the time).
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Range 4: 70% to 80%
Most important factors:
• Monitoring: General guidance exists for source specific enhanced monitoring, and monitoring records
required but aren't submitted to regulatory agency;
• Compliance history: In Violation; facility is in violation of emissions and/or procedural requirements.
Other important factors:
• Type of inspection: Inspections generally consist of only a records review;
• Operation & Maintenance: O&M requirements exist, but on no specific schedule;
• Unannounced inspections rarely done;
• Agency has the authority to impose punitive measures, including monetary fines, towards violators such as in
delegated Title V Operating Permit programs.
Other factors:
• Source not subject to any type of compliance certification;
• Inspection of source(s) infrequent; > every 5 years;
• Agency's resources allow it to implement EPA's 12/22/98 HPV policy more often than not;
• Media publicity of enforcement actions;
• Regulatory workshop not routinely available, but implementing agency mails regulatory information
packages out about once every 2-3 years;
• Inspectors must undergo 1 to 2 weeks of basic training and 1 to 3 days of source specific training, and such
training is updated every 1-2 years; Control equipment operators receive only on the job training ;
• Specific guidelines on testing and test methods, but no schedule for testing;
• Follow-up inspections infrequently done (approximately 25% of the time).
Range 5: Less than 70%
Most important factors:
• Monitoring: No requirements for any type of monitoring;
• Compliance history: High Priority Violator (HPV): the facility is in significant violation of one or more
applicable requirement of the CAA.
Other important factors:
Type of inspection: Inspections most likely consist of visual inspection (e.g., opacity), or drive by;
Operation & Maintenance: No specific O&M requirements;
Unannounced inspections never done;
Agency does not have sufficient authority to impose punitive measures towards violators;
Other factors:
Source not subject to any type of compliance certification;
Inspections rarely, if ever, performed;
Resource constraints prohibit agency from implementing EPA's 12/22/98 HPV policy inmost instances.
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• Control equipment operators receive no specific training;
• No media publicity of enforcement actions.
• Regulatory workshops not routinely available; implementing agency mails regulatory information packages
infrequently, if ever;
• Inspectors must undergo less than 5 days of basic training less than 3 days of source specific training, and
such training is updated only every 2 years or less frequently;
• Only general guidance on testing, or no mention of testing requirements.
• Follow-up inspections rarely or never done (10% of the time or less).
Attachment 2: Non-point source Rule Effectiveness Ranges
Range 1: 86 to 100%
Most important factor:
• Over 90% of facilities inspected in the source category are in compliance
Other important factors:
Source is subject to some type of compliance certification;
Inspections are thorough and detailed, and include close examination of control equipment, and a detailed
records review;
Unannounced inspections are sometimes done;
Percent of facilities inspected in the sector in a given year is 25% or greater;
Agency takes prompt enforcement action, including monetary fines, against violators;
A compliance assistance program exists and is adequately staffed, and includes such things as workshops,
mailings, web-based tutorials, etc.
Other factors:
• Monitoring requirements exist and must be reported to regulatory agency at least once a year;
• Follow-up inspections are done when violations are noted most (>75%) of the time;
• Media publicity of enforcement actions is routinely conducted.
Range 2: 70 to 85%
Most important factor:
• Over 75% of facilities inspected in the source category are in compliance
Other important factors:
• Source is subject to some type of compliance certification;
• Inspections consist of a records review, and sometimes inspection of control equipment;
• Unannounced inspections are done, but infrequently;
• Percent of facilities inspected in the sector in a given year is 15% or greater;
• Agency usually takes enforcement action, including monetary fines, against violators;
• A compliance assistance program exists, but is minimally staffed. The program occasionally makes
workshops, mailings, web-based tutorials, etc., available.
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Other factors:
• Monitoring requirements exist but records don't have to be filed with regulatory agency;
• Follow-up inspections are done when violations are noted most (>75%) of the time;
• Media publicity of enforcement actions is sometimes done.
Range 3: < 70%
Most important factor:
• Over 60% of facilities inspected in the source category are in compliance
Other important factors:
• Source is not subject to any type of compliance certification;
• Inspections generally consist of a records review only;
• Unannounced inspections are never done;
• Percent of facilities inspected in the sector in a given year is less than 15% ;
• Agency usually does not take enforcement action against violators;
• A compliance assistance program does not exist.
Other factors:
• Monitoring requirements do not exist;
• Follow-up inspections are not routinely done;
• Media publicity of enforcement actions is rarely if ever done.
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APPENDIX C
EPA420-B-05-008
United States . onnc
Environmental Protection August ZUln
Agency
Guidance for Creating Annual On-Road
Mobile Source Emission Inventories for PM2.5
Nonattainment Areas for
Use in SIPs and Conformity
Transportation and Regional Programs Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
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Background Information
The purpose of this document is to provide areas that are nonattainment or maintenance for the annual PM2 5 national
ambient air quality standard ("standard") with guidance on developing annual PM2 5 on-road motor vehicle emissions
estimates to meet state air quality implementation plan (SIP) and transportation conformity requirements.
For previous and existing air quality standards (e.g., 1 -hour ozone, 8-hour ozone, PM10 and carbon monoxide (CO)),
areas typically have been required to examine a typical summer or winter day because areas were violating a standard
established for a time period of 24 hours or less. As a result, these areas have developed on-road motor vehicle SIP
inventories, motor vehicle emissions budgets ("budgets"), and regional emissions analyses0 for transportation
conformity determinations using modeling inputs and parameters that were specific to a typical day within a
particular season. However, all areas currently designated nonattainment for PM2 5 are violating the annual standard
for this pollutant. In order to be consistent with this standard, these areas must develop annual emission inventories
for the purpose of developing SIP budgets and demonstrating transportation conformity. This guidance provides
information on how areas should fulfill these requirements.
The process for generating on-road motor vehicle emissions estimates for conformity purposes is commonly
referred to as a "regional emissions anaylsis" in conformity documents. However this term could be confused with
the process of creating an inventory for a SIP. To avoid that confusion, we will refer to a "refional emissions
analysis" for transportation conformity as a "regional conformity analysis" in this document.
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Table of Contents
1. Q. What effect does this guidance have on ozone, CO, and PM10 SIPs and regional conformity
analyses? C-4
2. Q. What are on-road motor vehicle emission inventories, budgets and regional conformity
analyses? C-4
3. Q. What pollutants and precursors are covered by this guidance? C-4
4. Q. Does this guidance create new requirements? C-5
5. Q. What emissions models should be used to develop SIP inventories and regional conformity analyses
for direct PM2 5 and PM2 5 precursors? C-6
6. Q. What issues should state and local air quality agencies and transportation agencies consider when
creating annual emissions inventories with MOBILE6.2 for SIPs and regional conformity
analyses? C-6
7. Q. What options do areas have to develop annual PM25 and PM25 precursor SIP inventories and
regional conformity analyses with MOBILE6.2? C-7
8. Q. How do emission factors for direct PM2 5 and for PM2 5 precursors vary with changes in external
commands? C-10
9. Q. What other requirements apply when calculating regional emissions for transportation
conformity? C-l 1
10. Q. For areas currently using network based travel models, does travel demand modeling need to be
done for each season or month? C-l 1
11. Q. Prior to the development of the PM2 5 SIP, can simpler methods be used for regional conformity
analyses? C-12
12. Q. Once the SIP budget is developed, should the same methods be used for regional conformity
analyses? C-12
13. Q. What is the National Mobile Inventory Model (NMIM) and how can it be used to determine annual
emissions inventories? C-13
14. Q. Who can I contact if I have further questions about developing annual PM25 SIP emissions
inventories and budgets, and regional conformity analyses? C-l4
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1. Q. What effect does this guidance have on ozone, CO, and PM10 SIPs and regional conformity
analyses?
A. This guidance applies to SIPs and regional conformity analyses for PM2 5 nonattainment and
maintenance areas that need to develop annual PM2 5 inventories, such as areas that are violating
the annual PM25 standard. Ozone, CO, and PM10 SIPs and regional conformity analyses should
continue to be based on inventories for a typical summer day or winter day, as applicable, using
appropriate MOBILE6.2 input conditions and vehicle miles traveled (VMT). Areas that need to
develop inventories for the 24-hour PM2 5 standard should follow existing guidance for creating
daily emission inventories.
2. Q. What are on-road motor vehicle emission inventories, budgets and regional conformity analyses?
A. An on-road motor vehicle emission inventory represents the total amount of emissions of a
particular pollutant or precursor that is emitted by cars, trucks, buses, and motorcycles in a given
area for a given point in time. The emissions reductions from on-road motor vehicle control
measures are also accounted for in the SIP inventory. When developing an attainment
demonstration, reasonable further progress (RFP) plan, or maintenance plan, areas are required to
develop emission inventories for all source categories (e.g., point, area, on-road motor vehicle and
off-road sources) for specific years. For some of these years, the on-road motor vehicle emission
inventory may also serve as the SIP budget that is used to demonstrate transportation conformity. A
budget provides a limit or ceiling on the amount of emissions transportation sources can produce in
a given area that is consistent with attainment, RFP or maintenance.
The transportation conformity rule (40 CFR parts 51 and 93), requires areas to demonstrate that
projected emissions from the planned transportation system do not exceed the budgets established
in the applicable SIP. Prior to an adequate or approved SIP budget, 40 CFR 93.109(i)(2) and
93.119(e) provide interim emissions tests that also require a regional conformity analysis. For
PM2 5 areas that need to do conformity for the annual PM2 5 standard, regional conformity analyses
should also represent total annual emissions for given years as required by 40 CFR 93.118 and
93.119.
In simplest terms, emissions estimates are created by multiplying emissions factors for a given
pollutant or precursor by the total number of vehicle miles traveled (VMT) in a given area for a
given year. This document provides guidance on how annual emissions estimates should be
developed for inventories, budgets, and regional conformity analyses for SIPs and conformity
purposes.
3. Q. What pollutants and precursors are covered by this guidance?
A. This guidance is applicable to the estimation of annual SIP and conformity inventories of direct
PM2 5 from motor vehicle tailpipe emissions, emissions from motor vehicle brake and tire wear,
and re-entrained road dust and construction dust from highway or transit projects. This guidance
would also apply, as applicable, to the estimation of annual inventories of applicable PM25
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precursors, i.e., volatile organic compounds (VOCs), nitrogen oxides (NOx), sulfur oxides (SOx),
and ammonia. EPA's future PM2 5 implementation rule will address when SIP inventories and
budgets are established for PM25 precursors. Requirements for inclusion of precursors in
transportation conformity analyses are addressed in a May 6, 2005, final rule (70 FR 24280) and
are specified at 40 CFR 93.102(b)(iv)-(v) and 93.119 (f)(9)-(10).
Consistent with the May 6, 2005, final rule, if on-road motor vehicle emissions of one or more
PM2 5 precursors are determined through the SIP development process to be significant contributors
to an area's PM2 5 nonattainment problem, an emissions budget for each significant precursor must
be established in the SIP. Alternatively, a PM2 5 SIP would not establish a motor vehicle emissions
budget for precursors that are determined to be insignificant through the SIP development process,
and regional emissions analyses for insignificant precursors would not be required for subsequent
conformity determinations. See the May 6, 2005, final rule for more information on the
requirements for addressing PM2 5 precursors in transportation conformity.
PM2 5 areas must also address re-entrained road dust in their conformity analyses, if a SIP
establishes an adequate or approved PM2 5 budget that includes re-entrained road dust. Prior to
adequate or approved budgets, areas must include road dust in conformity analyses only if EPA or
the State air agency finds road dust to be significant. Requirements for inclusion of road dust in
transportation conformity analyses can be found at 40 CFR 93.102(b)(3) and 93.119(f)(8).
Construction-related fugitive dust is not required to be included in any PM2 5 conformity
determinations before a SIP is submitted. As described in the conformity rule (40 CFR 93.122(f)),
construction dust is not required to be considered in the conformity process unless the PM25 SIP
identifies it as a significant contributor to the nonattainment area's PM2 5 problem. Areas that are
contemplating making this type of determination need to include specific information in their SIPs
in order to facilitate future conformity determinations. The inventories should clearly identify how
much of the regional construction dust is attributable to highway and transit construction, as
opposed to other construction activities. If the SIP is to identify construction dust emissions as a
significant contributor, the highway and transit construction dust emissions need to be included and
identified as such in the direct PM2 5 on-road motor vehicle emissions budget. In addition, the
regional conformity analysis would account for the level of construction activity, the fugitive PM2 5
control measures in the SIP (if there are any), and the dust producing capacity of the proposed
construction activities (November 5, 2003, 68 FR 62711).
4. Q. Does this guidance create new requirements?
A. No, this guidance is based on the existing Clean Air Act (CAA) and associated regulations and
does not create any new requirements. It merely explains how to fulfill current SIP and conformity
requirements for developing PM2 5 emission inventories and budgets.
The statutory provisions and EPA regulations described in this document contain legally binding
requirements. This document is not a substitute for those provisions or regulations, nor is it a
regulation itself. Thus, it does not impose legally binding requirements on EPA, states, or the
regulated community, and may not apply to a particular situation based upon the circumstances.
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EPA retains the discretion to adopt approaches on a case-by-case basis that may differ from this
guidance, but still comply with the statute and SIP and conformity regulations. Any decisions
regarding a particular SIP and conformity determination will be made based on the statute and
regulations. This guidance maybe revised periodically without public notice.
5. Q. What emissions models should be used to develop SIP inventories and regional conformity
analyses for direct PM2 5 and PM2 5 precursors?
A. For states other than California13, MOBILE6.2 is currently EPA's approved emission factor
model for estimating direct PM2 5 emissions from on-road vehicle exhaust and brake and tire wear,
and for PM2 5 precursor emissions from vehicle exhaust and evaporative emissions. For all states,
including California, the methods for estimating re-entrained road dust emissions from cars, trucks,
buses, and motorcycles on paved and unpaved roads are incorporated in Chapter 13 of AP-42.
These are EPA's approved methods for estimating road dust emissions. However, alternative
methods may be used if such methods are approved by EPA and announced in the Federal
Register. The use of MOBILE6.2 and AP-42, including discussion of alternatives to AP-42, in SIPs
and transportation conformity analyses is described in detail in a separate guidance documents
Chapter 13 of AP-42 includes information on the variability of re-entrained road dust emissions
based on environmental conditions, including factors that vary based on time of year. The AP-42
method can be used as described in Chapter 13 to develop annual re-entrained road dust inventories.
EPA plans on issuing separate guidance on how to apply adjustments to estimated road dust
emissions to reflect the true impact of re-entrained road dust on regional air quality in SIPs and
regional conformity analyses. The remainder of this document addresses the use of MOBILE6.2 to
calculate annual inventories for direct PM2 5 emissions from vehicle exhaust and brake and tire
wear, and for applicable PM2 5 precursor emissions from vehicle exhaust and evaporative emissions.
EPA has made available the National Mobile Inventory Model (NMIM), which incorporates
MOBILE6.2 as well as a database of local activity information and a post-processing system that
can produce annual emission inventories. NMEVI is an additional tool that can be used for inventory
development, although its use is not required. Question 13 of this document discusses the option to
use NMEVI in SIP development and regional conformity analyses.
State and local agencies developing SIPs and conformity analyses for California should consult with EPA
Region 9 for information on the current version of EMFAC approved for use in California and for information of
how to create annual inventories using EMFAC. However, the general concepts in this document for accounting for
variation during the year should be followed when creating annual inventories with EMFAC for the PM25 annual
standard.
E"Policy Guidance on the Use of MOBILE6.2 and the December 2003 AP-42 Method for Re-Entrained Road
Dust for SIP Development and Transportation Conformity", memorandum from Margo Oge and Steve Page to EPA
Regional Air Division Directors, February 24, 2004, which can be found at:
www.epa.gov/otaq/models/mobile6/mobil6.2 letter.pdf .
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6. Q. What issues should state and local air quality agencies and transportation agencies consider
when creating annual emissions inventories with MOBILE6.2 for SIPs and regional conformity
analyses?
A. State and local agencies need to consider whether MOBILE6.2 inputs or VMT vary during the
year enough to affect PM25 annual emissions estimates. MOBILE6.2 is designed to allow users to
estimate motor vehicle emissions based on specific input conditions that include month of
evaluation (i.e., January or July), environmental factors (e.g., temperature, humidity), fleet
characteristics (e.g., age distribution of fleet, distribution of VMT by vehicle class), activity
measures (e.g., speed distributions, distribution of VMT by roadway type), and fuel characteristics
(e.g., gasoline RVP, sulfur content). Some of these input conditions will vary based on time of year.
For some pollutants, these seasonal variations for certain input conditions will result in different
emissions estimates (these variations are discussed in more detail in Question 8). In addition to the
input conditions that affect MOBILE6.2 emission factors, VMT may also vary by time of year.
These differences in emission factors and VMT by time of year need to be considered in the
development of annual inventories.
The key question in the development of annual PM25 emissions estimates for SIPs and conformity is
how much temporal disaggregation of input data is needed to produce annual emissions inventories
that properly reflect local conditions. If, as a result of local conditions, MOBILE6.2 emissions
factors vary significantly over the course of the year, state air quality agencies and transportation
agencies may need to do multiple MOBILE6.2 runs with different input conditions to properly
develop SIP inventories and regional conformity analyses. State and local air quality and
transportation agencies should work together with EPA and the U.S. Department of Transportation,
via the interagency consultation process, to determine the appropriate inputs and number of
MOBILE6.2 runs needed to produce accurate annual inventories in a given nonattainment or
maintenance area. During the interagency consultation process, air quality and transportation
agencies should take into account the needs and capabilities of the air quality modeling tools that
will be used to develop the SIP, the availability of seasonal or monthly VMT and MOBILE6.2 input
data, and the seasonal or monthly variability of that data. Depending on the variability of input
conditions and the effect that variability has on emissions, state and local air quality and
transportation agencies in consultation with EPA and DOT may determine for some areas that a
single set of MOBILE6.2 runs is appropriate, or alternatively, that multiple sets of runs using
seasonal or monthly conditions are necessary.
7. Q. What options do areas have to develop annual PM2 5 and PM2 5 precursor SIP inventories and
regional conformity analyses with MOBILE6.2?
A. Depending on variability in local input conditions and on the impact of that variability on the
overall inventory, states may choose from a range of options for the degree of temporal
disaggregation used when creating annual inventories for SIPs and regional conformity analyses.
To determine how much temporal disaggregation is appropriate in a given area, states may choose
to calculate simplified annual emission inventories using the different approaches (i.e., run
MOBILE6.2 using representative annual and seasonal inputs) and compare the results. Through
this exercise, states may find that the differences between these methodologies are insignificant
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and further emissions analyses can be performed using a less detailed process. The interagency
consultation process should be used to determine which approach is most appropriate for a given
PM2 5 nonattainment or maintenance area. This process should include consultation among state
and local transportation and air quality agencies, as well as EPA and the U.S. Department of
Transportation. Whichever approach is chosen, that approach should be used consistently
throughout the analysis for a given pollutant or precursor. For example, if the 2002 base year
annual inventory used in the attainment SIP is based on an analysis using input assumptions broken
down for four seasons, the attainment year inventory used in that SIP should also be based on input
assumptions for four seasons.
The following are some examples of methodologies that could be used. Other approaches may also
be appropriate as determined through the interagency consultation process.
Developing Annual Inventories and Regional Conformity Analyses Using Annual Average
MOBILE6.2 Inputs and a Single Set of MOBILE6.2 Runs
Single-Run Approach: This methodology would involve a single set of modeling runs with
MOBILE6.2 for each year or scenario using only annual average inputs for all MOBILE6.2 input
parameters and for VMT. EPA believes that in some areas this methodology may be appropriate
because some input conditions may not vary significantly by time of year in a particular area. For
example, distribution of VMT by vehicle class maybe fairly constant in most areas. In addition,
some input conditions may vary without affecting the emissions estimates for some pollutants
generated by MOBILE6.2. For example, direct PM25 emissions in MOBILE6.2 are insensitive to
differences in ambient temperature and humidity (these cases are described in more detail in
Question 10).
States should determine which input conditions do not vary significantly during the year. For these
conditions, annual average input values may suffice. If local conditions are such that there is no
significant variation in emissions derived from MOBILE6.2 based on time of year, state and local
air quality and transportation agencies, in consultation with EPA and DOT, may choose to base
annual SIP inventories and regional conformity analyses on MOBILE6.2 runs based on a single set
of inputs and using total annual VMT. For this approach, the evaluation month in MOBILE6.2
should be July of the calendar year being evaluated.
Developing Annual Inventories and Regional Analyses Using Seasonal or Monthly Average
MOBILE6.2 Inputs and Two or More Sets of MOBILE6.2 Runs
In some cases, variations in input conditions at different times of the year may result in significant
differences in MOBILE6.2 emission factors. In some areas, there may also be significant
differences in VMT at different times of the year. In these areas, developing inventories based on
seasonal average input conditions may be necessary. Depending on the temporal variability of
input data for a given area, from two to twelve sets of modeling runs with MOBILE6.2 maybe
used for each year or scenario. Some possible approaches are included below, but this does not
include a comprehensive list of options. State and local air quality and transportation agencies, in
consultation with EPA and DOT, should choose the approach that best suits local conditions.
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Two-Season Approach: This approach uses winter and summer input conditions to develop
inventories based on two sets of MOBILE6.2 runs. This approach assumes that each set of input
conditions can be used to model six months of the year. The "winter" inventory would be based on
average input conditions for the coldest months of the year and the "summer" inventory would be
based on average input conditions for the hottest months of the year. Annual VMT would be
apportioned as appropriate to the winter or summer runs. If VMT does not vary significantly by
season, half of the annual VMT could be apportioned to each of the two sets of MOBILE6.2 runs
to create winter and summer inventories. If VMT is significantly different between the "winter"
and "summer" seasons, then the VMT should be apportioned based on those differences.
Under this approach, the total annual inventory for an area would be the sum of the "winter" and
"summer" inventories. For this approach, January should be used as the input for evaluation month
in MOBILE6.2 for the "winter" inventory and July should be used for the "summer" inventory.
Because the evaluation month input in MOBILE6.2 can also affect fuel parameters, MOBILE6.2
users should take care to ensure that model inputs for fuel parameters are set to properly represent
the season modeled.
Four-Season Approach: This approach bases the total annual inventory on four sets of seasonal
input conditions and four sets of MOBILE6.2 runs: winter, spring, summer, and fall. This approach
assumes that four sets of inputs are used, one for each of the four seasons. VMT would be
apportioned appropriately for each of these seasonal periods. If VMT does not vary significantly by
season, one quarter of the annual VMT would be apportioned to each of the seasonal inventories. If
VMT is significantly different between the seasons, then the VMT should be apportioned based on
those differences.
The total annual inventory for an area would be the sum of the four seasonal inventories.
MOBILE6.2 only has two input options for evaluation month (January and July). January should
be used as the input for evaluation month in MOBILE6.2 for the winter inventory and July should
be used for the summer inventory. For the spring inventory, July should be used as the input for
evaluation month in MOBILE6.2, while January of the following year should be used as the input
for the fall inventory. Because the evaluation month input in MOBILE6.2 can also affect fuel
parameters, MOBILE6.2 users should take care to ensure that model inputs for fuel parameters are
set to properly represent the season modeled.
Monthly Approach: Another available approach for developing annual inventories and regional
conformity analyses would involve twelve sets of MOBILE6.2 modeling runs using monthly
average input conditions and VMT. As a result, this methodology is more resource intensive than
the previous approaches. States should note that this is the approach that is used to create the 2002
National Emission Inventory (NEI) that some areas may use as their 2002 base year inventory for
SIP purposes. For detailed guidance on how to set the evaluation month in MOBILE6.2 to prepare
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monthly inventories for calculation of annual inventories, see Section 2.2 of EPA's "Technical
Guidance on the Use of MOBILE6.2 for Emission Inventory Preparation"11.
States that wish to use this approach may also want to consider using the NMIM model to reduce
the amount of data processing needed. See Question 13 below for more information on the use of
NMIM in developing annual inventories and regional emissions analyses.
Q. How do emission factors for direct PM25 and for PM25 precursors vary with changes in external
commands?
A. MOBILE6.2 uses different algorithms to estimate emissions from different pollutants. Inputs
that contribute to seasonal variability in emissions for some pollutants may not result in variability
for others. As a result, state and local agencies may be able to use simpler approaches for some
pollutants than for others.
Direct PM, s. SOx. and Ammonia
MOBILE6.2 uses simple algorithms to estimate direct PM2 5 emissions and SOx, and ammonia
precursor emissions. In general, emissions of these pollutants and precursors do not vary, or vary
only by small amounts, for most of the input conditions in MOBILE6.2, including key commands
such as temperature, humidity, vehicle speed, and roadway type.
However, emission factors for direct PM2 5 emissions and SOx and ammonia precursor emissions
are affected by the following MOBILE6.2 input options:
• Registration (age) distribution
• Diesel sales fractions
• Annual mileage accumulation rates
• Distribution of VMT by vehicle class
• Input options that affect gasoline and diesel fuel sulfur content
Of these input options, registration distribution, diesel sales fractions, and annual mileage
accumulation rates should not change based on time of year. If the remaining parameters do not
vary significantly by time of year, a single set of MOBILE6.2 runs, using July as the evaluation
month, may be sufficient to develop annual inventories for SIPs and regional conformity analyses
for direct PM2 5, SOx, and ammonia.
NOx and VOC
"Technical Guidance on the Use of MOBILE6.2 for Emission Inventory Preparation", Office of
Transportation and Air Quality, US EPA, August 2004, EPA420-R-04-013, which can be found at
www.epa.gov/otaq/m6.htm.
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MOBILE6.2 emissions estimates of NOx and VOC precursor emissions are affected by
temperature and humidity, fleet characteristics (e.g., age distribution of fleet, distribution of VMT
by vehicle class), activity measures (e.g., speed distributions, distribution of VMT by roadway
type), and fuel characteristics (e.g., gasoline RVP, sulfur content). When evaluating which
approach to use for generating annual inventories for NOx and VOC, states should first consider
which of the input conditions actually vary significantly based on time of year. States can then test
whether those variations are likely to result in significant differences in emissions throughout
different times of the year, as appropriate.
Based on an analysis of various parameters, states may conclude that simpler methods (i.e., the
annual or seasonal methods) can be used to develop direct PM2 5 inventories than are needed for
PM2 5 precursors such as NOx and VOC. The interagency consultation process should be used to
determine if the use of different approaches for direct PM2 5 and for PM2 5 precursors would ease
the resource burden of developing SIPs and conformity analyses while maintaining credible results.
9. Q. What other requirements apply when calculating regional emissions for transportation
conformity?
A. Section 93.122 of the transportation conformity rule contains requirements for estimating VMT
and inclusion of control measures in regional conformity analyses. Section 93.122(b) of the
transportation conformity rule requires that serious, severe and extreme ozone nonattainment areas
and serious CO nonattainment areas use network based travel models to perform regional
conformity analyses. There is no similar requirement to use network based travel models for PM25
nonattainment areas. However, PM2 5 areas that are currently using network based travel models
must continue to use them when calculating annual emission inventories, per Section 93.122(d).
Areas without a network based travel model may use other appropriate methods for estimating
VMT consistent with best professional practice and Section 93.122(d) of the conformity regulation.
In addition, sections 93.110 and 93.111 require the latest planning assumptions and emission
models to be used in all conformity analyses.
10. Q. For areas currently using network based travel models, does travel demand modeling need to be
done for each season or month?
A. In some areas, variations in VMT or other vehicle activity inputs over the course of the year
may not have a significant effect on MOBILE6.2 emissions estimates for direct PM25 or PM25
precursors. In such cases, a single travel demand modeling run would be sufficient to generate an
annual VMT estimate or any other activity inputs derived from the travel model. Annual VMT
estimates would then be divided appropriately according to the level of temporal disaggregation
used for the emissions estimation as described in Question 7.
State and local air quality and transportation agencies, in consultation with EPA and DOT, should
determine whether significant seasonal variations in the output of network based travel models is
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expected and whether these variations would have a significant impact on PM2 5 emissions
estimates. The interagency consultation process should be used to determine the most appropriate
method for estimating VMT and identifying the appropriate source for existing VMT data.
11. Q. Prior to the development of the PM2 5 SIP, can simpler methods be used for regional conformity
analyses?
A. Yes. EPA expects that the most thorough analysis to determine the appropriate methods to be
used for developing annual inventories will occur during the development of the SIP, taking into
account the needs and capabilities of air quality modeling tools and the limitations of available
data. Prior to the development of the SIP, state and local air quality and transportation agencies
may not have all of the information they need to determine how much temporal disaggregation is
necessary to adequately account for variation in emissions during the year. State and local agencies
may also need additional time to collect data on a seasonal or monthly basis if that data is needed.
For these reasons, state and local air quality and transportation agencies may, through the
interagency consultation process, decide to use simplified methods for regional conformity
analyses done prior to an adequate or approved SIP budget. For example, through the interagency
consultation process, state and local agencies may choose to base regional conformity analyses
used in interim conformity tests (build-no-greater-than-no-build or no-greater-than-2002 tests) on
average annual inputs and a single set of MOBILE6.2 runs even while they are working on
developing an RFP, attainment, or maintenance SIP using a more complicated approach.
Whatever approach is selected, the latest planning assumptions, latest emissions model, and
appropriate methods for estimating travel and speeds must be used as required by Sections 93.110,
93.111, and 93.122 of the conformity rule. Also, the approach that is selected for the interim
emissions tests should be used consistently when completing a conformity test. Whether a
submitted or draft 2002 SIP inventory or some other inventory determined through the interagency
consultation process is used, the regional conformity analysis for the baseline year test should be
based on the same approach that was used to develop the baseline inventory for conformity
purposes. For example, if the two-season approach is used to develop the 2002 baseline year for
conformity purposes, the same two-season approach should be used for the regional conformity
analysis. See the preamble of the July 1, 2004 conformity rule (FR 40015 left column) for more
information on considerations for the 2002 baseline test. Similarly, the same approach should be
used to develop the build and no-build scenarios under the build-no-greater-than-no-build test.
12. Q. Once the SIP budget is developed, should the same methods be used for regional conformity
analyses?
A. Yes. Regional conformity analyses should be based on the same approach used to develop the
direct PM25 and any PM25 precursor budgets established in the applicable SIP. For example, if the
NOx SIP budget was determined using average seasonal inputs in MOBILE6.2 for winter, spring,
summer, and fall, the same approach should be used for regional conformity analyses based on that
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budget. State and local air quality and transportation agencies should use the interagency
consultation process while developing the approach used for the SIP budgets to consider the impact
this will have on data collection, modeling, and analysis needs for future regional conformity
analyses.
13. Q. What is the National Mobile Inventory Model (NMIM) and how can it be used to determine
annual emissions inventories?
A. NMIM is a graphical user interface that contains the MOBILE6.2 and NONROAD0 models and
a database of county-level input information, the National County Database (NCD). NMIM
produces monthly inventories by source classification code (SCC) and county. When using NMIM,
users can simply select the year, months, and county or counties they wish to evaluate. Since
NMIM includes county-level information, it will automatically write MOBILE6.2 input files, run
MOBILE6.2 and multiply the emission factors by VMT to produce emission inventories for each
county for each month.H NMIM also provides a post-processing module that will aggregate the
months into an annual inventory and produce tab-delineated ASCII output that can be read into
database or spreadsheet software applications.
NMIM is not considered a new model and does not start a new conformity grace period pursuant to
40 CFR 93.111. Because NMIM incorporates MOBILE6.2, it may be used to generate emissions
inventories for SIPs and regional conformity analyses. NMEVI may provide an easier way for states
to develop annual inventories because it is designed to create annual inventories based on monthly
inputs. However, before using NMIM, state and local air quality and transportation agencies should
work together with EPA and DOT to determine whether NMIM is appropriate given local
conditions and modeling methods and to determine what modifications, if any, are needed to the
NMIM database to accurately model current local conditions.
The use of NMIM is not required for SIPs or regional conformity analyses. Some areas may choose
not to use NMIM simply because it does not provide a significant resource advantage compared to
pre- and post-processing methods already being used. State and local agencies should carefully
review the NMEVI documentation before deciding whether to use it. NMIM has some limitations in
some applications and, as a result, the use of NMEVI may not be appropriate in all areas. For
example, some areas may already be using more sophisticated methods for pre- and post-
Because it incorporates MOBILE6.2 and NONROAD, NMIM can be used to generate emissions inventories
for both on-road motor vehicles (cars, trucks, buses, and motorcycles) and off-road equipment (agricultural and
construction equipment, lawn and garden equipment, and off-road recreational vehicles among others) for SIP
purposes. Because transportation conformity applies only to on-road motor vehicles, only the on-road portion of an
inventory generated using NMIM would be used to generate SIP budgets and regional conformity analyses.
TT
"EPA's National Mobile Inventory Model (NMIM), A Consolidated Emissions Modeling System for
MOBILE6 and NONROAD". H. Michaels, et al. U.S. EPA. www.epa.gov/otaq/models/nmim/420r05003.pdf.
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processing input and emissions data than NMIM can accommodate. In that case, state and local
agencies should not use NMIM.
States have provided information for the NCD as part of the National Emissions Inventory (NEI)
development process. However, given the NEI cycle, this may not be the most recent or best
available information at the time a state initiates modeling as required in the latest planning
assumptions provisions of the conformity rules (40 CFR 93.110). For SIPs and regional conformity
analyses, state and local agencies should review the information in the NCD to verify that it is still
accurate and up-to-date. Where more current information is available, the database must be
modified to incorporate the most recent data to meet latest planning assumptions requirements for
SIPs and conformity. (EPA encourages states to separately submit updates to the NCD so that the
most accurate database is available for both national and local inventory development). The NCD
works at the county level and will need to be modified to account for areas containing partial
counties, if necessary. The interagency consultation process should be used to evaluate whether the
use of NMIM is appropriate in a given area, and to evaluate what changes are needed in the NMIM
database.
State and local agencies should take special care to ensure that VMT data used in NMEVI is derived
appropriately. Areas required to use VMT data from travel demand models need to make sure that
the appropriate VMT estimates are incorporated into the NCD. One limitation of the NCD is that it
includes VMT data for only select years but not necessarily for the years that need to be evaluated
for SIP or transportation conformity purposes. Therefore, even if the VMT data in the NCD are
correct for a specific year, areas wishing to use NMEVI may need to calculate and enter the
necessary VMT inputs for other years into the NCD. Areas should also evaluate the speed
assumptions in the NCD and revise them as needed to reflect current local estimates.
The current version of NMEVI is available at www.epa.gov/otaq/nmim.htm. EPA is currently
working on updates to the NONROAD portion of NMEVI and to the NCD and expects to release a
revised version of NMIM later in 2005, which will be posted on the website and notice sent out
through our list-server.
14. Q. Who can I contact if I have further questions about developing annual PM2 5 SIP emissions
inventories and budgets, and regional conformity analyses?
A. For specific questions about a particular nonattainment or maintenance area, please contact the
SIP or transportation conformity staff person responsible for your state at the appropriate EPA
regional office. A listing of regional offices, the states they cover, and contact information for EPA
regional conformity staff can be found at the following website:
www.epa.gov/otaq/transp/conform/contacts.htm.
General questions about this guidance can be directed to Gary Dolce at EPA's Office of
Transportation and Air Quality, dolce.gary@epa.gov or 734-214-4414.
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United States Office of Air Quality Planning and Standards Publication No. EPA - 454/R-05-001
Environmental Protection Emissions, Monitoring and Analysis Division August 2005
Agency Research Triangle Park, NC
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