Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT 

# DRAFT



# Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze RegulationsEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

i 

## Table of Contents List of Table s

................................ ................................ ................................ ................................ ................. v Acronyms and Abbreviations Used in this Guidance

................................ ................................ ................... vi
1 Introduction

................................ ................................ ................................ ................................ .......... 1
1.1 Purpose

................................ ................................ ................................ ................................ ......... 1
1.2 Other Inventory Guidance and Resources

................................ ................................ .................... 2
1.3 Summary of Relevant Statutory Provisions

................................ ................................ .................. 4
1.4 Summary of Guidance Contents

................................ ................................ ................................ ... 7
2 SIP Inventory Overview

................................ ................................ ................................ ......................... 8
2.1 Recommended Steps f or Building the Inventory Parts of a SIP

................................ .................... 8
2.2 Discuss the Inventory Approval Process with EPA

................................ ................................ ...... 10
2.3 Planning and Modeling Invent ory Components

................................ ................................ ......... 12
2.3.1 Ozone SIP Inventory Components

................................ ................................ ...................... 13
2.3.2 Annual and 24

- Hour PM 2.5 SIP Inventory Components

................................ ...................... 14
2.3.3 Regional Haze SIP Inventory Components

................................ ................................ .......... 15
2.4 Other Relevant Federal Emissions Reporting Requirements

................................ ...................... 18
2.5 Emissions Inventory Definitions

................................ ................................ ................................ .. 19
2.5.1 Source Category/Data Category

................................ ................................ ......................... 19
2.5.2 Types of Emissi ons: Annual, Seasonal, Actual, Potential, and Allowable

........................... 20
2.5.3 Duration and Timing of Emissions

................................ ................................ ...................... 21
2.5.4 Data Elements

................................ ................................ ................................ ..................... 21
2.5.5 Throughput and Activity

................................ ................................ ................................ ..... 22
2.5.6 Emission Factors

................................ ................................ ................................ .................. 22
2.5.7 Emission s Reporting Data Elements

................................ ................................ ................... 23
2.5.8 Point Sources

................................ ................................ ................................ ...................... 25
2.5.9 Nonpoint Sources

................................ ................................ ................................ ................ 26
2.5.10 On

- road Mobile Sources

................................ ................................ ................................ ..... 26
2.5.11 Nonroad Mobile Sources

................................ ................................ ................................ .... 27
2.5.12 Events

................................ ................................ ................................ ................................ .. 28
2.5.13 Biogenic Sources

................................ ................................ ................................ ................. 28
2.5.14 Inventory Codes

................................ ................................ ................................ .................. 28Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

ii 2.5.15 Point Source Facility Details

................................ ................................ ................................ 30
2.5.16 Alternative IDs

................................ ................................ ................................ ..................... 31
2.5.17 Location Definitions

................................ ................................ ................................ ............ 32
2.5.18 Control Data Elements

................................ ................................ ................................ ........ 33
2.5.19 EIS Sectors, Tiers, and Facility Type

................................ ................................ .................... 34
2.5.20 Other Terms

................................ ................................ ................................ ........................ 34
3 SIP Inventory Requirements and Recommendations

................................ ................................ ......... 35
3.1 Inventory Component Timing

................................ ................................ ................................ ..... 35
3.2 Inventory Preparation Pla n

................................ ................................ ................................ ......... 36
3.3 Base Year Inventory

................................ ................................ ................................ .................... 39
3.4 Rate of Progress and Reasonable Further Progress Baseline NAA Inventory

............................. 40
3.4.1 Ozone ROP/RFP Requirements and Timing

................................ ................................ ........ 40
3.4.2 Ozone ROP/RFP Emissions Guidance

................................ ................................ .................. 41
3.4.3 PM 2.5 RFP Requirements and Timing

................................ ................................ .................. 42
3.4.4 PM 2.5 RFP Emissions Guidance

................................ ................................ ............................ 42
3.5 Periodic Inventories

................................ ................................ ................................ .................... 43
3.5.1 Ozone Periodic Inventory

................................ ................................ ................................ .... 43
3.5.2 Regional Haze Recent Year Inventory

................................ ................................ ................. 44
3.6 Em issions Statement Requirement for SIPs

................................ ................................ ................ 45
3.7 Maintenance Inventories

................................ ................................ ................................ ............ 46
3.8 Projected Inventories

................................ ................................ ................................ .................. 46
3.8.1 Attainment Year Projected Inventories

................................ ................................ .............. 48
3.8.2 Rate of Progress and Reasonable Further Progress Emissions Reductions

........................ 49
3.8.3 Regional haze emissions reductions

................................ ................................ ................... 50
3.9 Public Hearings

................................ ................................ ................................ ............................ 50
3.10 Submit Inventory Parts of S IP to the EPA

................................ ................................ ................... 51
3.10.1 Regulatory Requirements in Addition to Implementation Rules

................................ ........ 52
3.10.2 How to Submit Inventory Parts of a S IP

................................ ................................ .............. 53
3.10.3 What to Submit

................................ ................................ ................................ ................... 54
4 Developing Current Emissions inventories

................................ ................................ ......................... 59
4.1 Inventory Years

................................ ................................ ................................ ........................... 59
4.1.1 Ozone baseline year

................................ ................................ ................................ ............ 59Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

iii 4.1.2 PM 2.5 ................................ ................................ ................................ ................................ .... 60
4.1.3 Regional Haze

................................ ................................ ................................ ...................... 61
4.1.4 Considerations for choosing an alternative base year

................................ ........................ 62
4.2 Pollutants and Pollutant Precur sors to Include in Inventories

................................ ................... 62
4.2.1 Condensable PM emissions

................................ ................................ ................................ 63
4.2.2 Regulatory Definition of VOC

................................ ................................ .............................. 65
4.2.3 Treatment of Methane

................................ ................................ ................................ ....... 65
4.3 Identification of Priority Sources

................................ ................................ ................................ 66
4.4 Spatial Extent

................................ ................................ ................................ .............................. 69
4.4.1 Nonattainment Areas with Partial Counties

................................ ................................ ....... 69
4.4.2 Point Source Locations Needed for Modeling of Traditional Nonpoint Sou rces

................ 71
4.4.3 Shapefile

- based Inventories

................................ ................................ ................................ 71
4.4.4 Link

- based On

- road Mobile Emissions and Travel Demand Models

................................ .. 71
4.5 Temporal Basis

................................ ................................ ................................ ............................ 72
4.5.1 Temporal Considerations for Ozone SIPs

................................ ................................ ............ 72
4.5.2 Tempor al Considerations for PM 2.5 SIPs

................................ ................................ ............. 73
4.6 Emission Factors for SIP Emissions Inventories

................................ ................................ .......... 74
4.7 Inventory Data Codes

................................ ................................ ................................ .................. 76
4.7.1 Codes to Use for Nonattainment Area Inventories

................................ ............................ 76
4.7.2 How to Request New Codes or Code Retirements

................................ ............................. 76
4.8 Estimation of Base Year Emissions

................................ ................................ .............................. 77
4.8.1 Stationary Point

................................ ................................ ................................ .................. 77
4.8.2 Stationary Nonpoint

................................ ................................ ................................ ............ 82
4.8.3 On

- road Mobile

................................ ................................ ................................ ................... 85
4.8.4 Nonroad Mobile Equipment

................................ ................................ ............................... 86
4.8.5 Other Nonroad Mobile

................................ ................................ ................................ ........ 87
4.8.6 Biogenic and Geogenic Sources

................................ ................................ .......................... 95
4.8.7 Wildland Fires

................................ ................................ ................................ ..................... 98
4.9 Quality Assurance

................................ ................................ ................................ ..................... 101
4.9.1 QA Reference Materials and Planning

................................ ................................ .............. 102
4.9.2 Types of Problems in Emissions Invent ories

................................ ................................ ..... 102
4.9.3 Checks Available through the EPA’s Emissions Inventory System

................................ .... 103Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

iv 4.9.4 Inventory Comparisons

................................ ................................ ................................ ..... 104
4.9.5 Checking Data Codes

................................ ................................ ................................ ......... 105
4.9.6 Point Versus Nonpoint and Reconciliation

................................ ................................ ....... 105
4. 9.7 Ranking Techniques

................................ ................................ ................................ .......... 106
4.9.8 Outlier Analyses

................................ ................................ ................................ ................ 107
4.9.9 Using Maps to QA Nonpoint Emissions

................................ ................................ ............ 108
4.9.10 Expected Pollutants

................................ ................................ ................................ .......... 108
4.9.11 Facility and Release Point Locations

................................ ................................ ................. 109
4.9.12 Release Poi nt Parameters

................................ ................................ ................................ . 110
4.9.13 Biogenic QA/QC

................................ ................................ ................................ ................. 111
4.9.14 Timing of QA and Follow

- up

................................ ................................ ............................. 111
5 Developing Projected Emissions Inventories

................................ ................................ .................... 113
5.1 Projected Emissions Overview

................................ ................................ ................................ .. 113
5.1.1 Readily Available Proje ctions Information

................................ ................................ ........ 113
5.1.2 Background Materials

................................ ................................ ................................ ....... 113
5.2 Identify and Prioritize Key Sectors and Regions for Projections

................................ ............... 115
5.3 Collect Available Data and Models for Each Sector Needing Projections

................................ 115
5.3.1 Electric Generating Units

................................ ................................ ................................ .. 116
5.3.2 Non

- EGU Stationary Sources

................................ ................................ ............................ 121
5.3.3 On

- Road Mobile Sources

................................ ................................ ................................ .. 122
5.3.4 Nonroad Mob ile Equipment

................................ ................................ ............................. 123
5.3.5 Other Nonroad Mobile Sources

................................ ................................ ........................ 123
5.3.6 Other Projection Resources

................................ ................................ .............................. 124
5.4 Evaluate and Refine Data for Projections in Inventory Region

................................ ................. 127
5.5 QA for Projected Inventories

................................ ................................ ................................ .... 128
6 References

................................ ................................ ................................ ................................ ........ 129Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

v 

## List of Tables Table 1: List of EPA estimation resources for emissions inventories

................................ ........................... 2 Table 2: Steps for building the inventory parts of a SIP

................................ ................................ ................ 9 Table 3: Recommended items to include in inventory information provided to the EPA

.......................... 12 Table 4: Ozone SIP emissions inventory components

................................ ................................ ................ 13 Table 5: PM 2.5 SIP emissions inventory components

................................ ................................ .................. 14 Tabl e 6: Regional haze SIP emissions inventory components

................................ ................................ .... 17 Table 7: Point source triennial reporting thresholds (potential to emit) for criteria pollutants in the Air Emissions Reporting Rule

................................ ................................ ................................ . 26 Table 8: Timing of emissions inventory components

................................ ................................ ................. 35 Table 9: Checklist of elements to consider for including in Inventory Prepa ration Plans

.......................... 37 Table 10: Conditions for AERR submittal to meet ozone periodic inventory requirement

........................ 44 Table 11: Suggested Elemen ts of an Emissions inventory SIP Document

................................ .................. 55 Table 12: Summaries to include in the background

................................ ................................ ................... 56 Table 13: Summaries to include in the point sources section

................................ ................................ .... 57 Table 14: Summaries to include in the nonpoint and mobile sources sections

................................ ......... 57 Table 15: Source types expected to include condensable PM

................................ ................................ ... 63 Table 16: Hierarchy of emission factors for use in point source emissions inventories

............................ 75 Ta ble 17: List of nonpoint categories, pollutants, and available approaches and tools

............................. 83 Table 18: Aircraft SCCs and Data Categories in EPA Estimates

................................ ................................ ... 88 Table 19: Commercial marine SCCs and emission types in EPA emissions

................................ ................. 91 Table 20: Commercial marine vessel recent regulations and impacted pollutants

................................ ... 91 Table 21: Current EPA methods for commercial marine vessel emissions.

................................ ............... 92 Table 22: Locomotive SCCs

................................ ................................ ................................ ......................... 94Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

vi 

## Acronyms and Abbreviations Used in this Guidance
AEO Annual Energy Outlook AERR Air Emissions Reporting Rule APU Auxiliary power unit BEIS Biogenic Emission s Inventory System BELD3 Biogenic Emissions Land U se Database, version 3 AT Air Taxis C1 Category 1 (marine vesse l) C2 Category 2 (marine vessel) C3 Category 3 (marine vessel) CAA Clean Air Act CAMD Clean Air Markets Division CAP Criteria air pollutant CAS Chemical Abstracts Service CEM S Continuous Emissions Monitoring System(s) CMV Commercial marine vessel CNG Compr essed natural gas CO Carbon monoxide CO2 Carbon dioxide DARS Data Attribute Rating System DOE Department of Energy ECA

- IMO Emissions Control Area

- International Maritime Organization EDD Effective date of designation EDMS Emissions and Dispersion Modeling S ystem EE Energy efficiency EGU Electric Generating Unit EIA Energy Information Administration EIIP Emissions inventory Improvement Program EIS Emission s Inventory System EMCH Emissions Modeling Clearinghouse EPA Environmental Protection Agency EPM M Electri c Power Market Model ERTAC Eastern Regional Technical Advisory Committee FAA Federal Aviation Administration FHWA Federal Highway Administration FIPS Federal Information Processing Standards FRS Federal Registry Service GA General Aviation GHG Greenhouse g as GIS Geographic Information Systems GSE Ground support equipmentEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

vii HAP Hazardous air pollutant Hg Mercury HCl Hydrochloric acid IPM Integrated Planning Model IPP Inventory Preparation Plan LPG Liquified petroleum gas LTO Landing and takeoff MARKAL M ark et A ll ocation (model) MEGAN Model of Emissions of Gases and Aer o sols from Nature MIMS Multimedia Integrated Modeling System MOVES Motor Vehicle Emissions System NAAQS National Ambient Air Quality Standards NAA Nonattainment area NAICS North American Industry C lassification System NATA National Air Toxics Assessment NEEDS National Electric Energy Data NEI National Emissions Inventory NEMS National Energy Modeling System NESHAP National Emission Standard for Hazardous Air Pollutants NH 3 Ammonia NLDN National Ligh tning Dete ction Network NMIM National Mobile Inventory Model NONROAD Nonroad emissions model NMHC Non

- methane hydrocarbon NO X Nitrogen Oxides O 3 Ozone OAP Office of Atmospheric Programs OAQPS Office of Air Quality Planning and Standards OAR Office of Air a nd Radiation OECA Office of Enforcement and Compliance Assurance ORIS Office of Regulatory Information Systems OTAQ Office of Transportation Air Quality OTR Ozone Transport Region PM Particulate m atter PM 2.5 Particulate matter with diameter 2.5 microns and less PM 10 Particulate m atter with diameter 10 microns and less QAPP Quality Assurance Project Plan RE Renewable energy RICE Reciprocating Internal Combustion Engines RFP Reasonable Further Progress ROP Rate of Progress SCC Source classification codeEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

viii SIP S tate implementation p lan SMOKE Sparse Matrix Operator Kernel Emissions SO 2 Sulfur Dioxide SSM Startup, Shutdown, and Malfunction STEEM Ship Traffic, Energy and Environmental Model TAF Terminal Area Forecast TCA 1,1,1

- trichloroethane TDM Travel demand model TIP Tribal Implementation Plan TOG Total organic gases TRI Toxics Release Inventory U

. S

. United States USDA U.S. Department of Agriculture VMT Vehicle miles traveled WFU Wildland fire use WLF Wildland fire WRF Weather Research and Forecasting VOC Volatile organic compoundsEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

1 

## 1 Introduction

1.1 Purpose This document provides guidance on how to develo p emissions inventories to meet state implementation p lan (SIP) requirements for complying with the 8

- hour ozone national ambient air quality standard (NAAQS), the 2 4

- hour and annual fine particulate matter (PM 2.5 ) NAAQS, and the regional haze regulations

. It is intended for use by the United States (U

. S

. ) Environmental Protection Agency (EPA) Regional office s; state, local , and t ribal air quality management authoriti es; and the general public

. Th is guidance is designed to implement national policy on these emissions inventories as embodied in the Clean Air Act (CAA) , the Ozone SIP Requirements Rule for the 2008 ozone NAAQS (also called the Ozone Implementation Rule) 1
, the PM 2.5 SIP Requirements Rule 2 , and the Regional Haze Regulations

. 3
This document does not substitute for provisions or r egulations of the CAA enumerated above, nor is it a regulation itself

. As the term “guidance ” suggests, it provides recommendations on how to implement the inventory requirements

. Thus, it does not impose binding, enforceable requirements on any party, nor does it assure that the EPA will approve all instances of its application, as the guidance may not apply to a particular situation based upon the circumstances

.
The EPA and s tate , local, and t ribal decision makers retain the discretion to adopt approaches on a case

by

- case basis that differ from this guidance where appropriate

. Final decisions by the EPA regarding a particular SIP de monstration will only be made based on the statute and regulations, and will only be made following a final submission and after notice and opportunity for public review and comment

. Interested parties are free to raise questions and objections about the a ppropriateness of the application of this guidance to a particular situ ation; the EPA will, and state, local, and tribal air agencies should, consider whether or not the recommendations in this guidance are appropriate in that situation.
Through the provis ions of the T ribal Authority Rule, t ribes are not required to develop emissions inventories

. If tribe s choose to develop an emissions inventory that may become part of a SIP or Tribal Implementation Plan (TIP) inventory covered by this guidance, the tribe s are encouraged to follow the provisions of this guidance

. Notwithstanding the possible development by local and tribal air agencies, inventories prepared for NAAQS implementation will be called “ SIPs ” in the remainder of this document.

1 Implementation of the 2008 National Ambient Air Quality Stan dards for Ozone: State Implementation Plan Requirements; (40 CFR 51 Subpart AA; see also https://www.epa.gov/ozone

- pollution/imp lementation

- 2008

- national

- ambient

- air

- quality

standards

- naaqs
- ozone
- state ).
2 Fine Particulate Matter National Ambient Air Quality Standards: State Implementation Plan Requirements, ( 40 CFR 51 Subpart Z; see also https://www.epa.gov/pm

- pollution/implementation

- national

- ambient

- air

- quality

- standards

- naaqs
- fine

particulate

- matter ).
3 Re gional Haze Regulations (40 CFR 51 Subpart P) proposed to be amended by Protection of Visibility: Amendments to Requirements for State Plans; Proposed Rule (81 FR 26942, May 4, 2016). See also https://www.epa.gov/visibility/visibility

regulatory

- actions

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

2 

### 1.2 Other Inventory G ui dance and R esources This document is a guide for state, local, and tribal air agencies (called “air agencies” in this guidance) for preparing and submitting their emissions inventories for the 8

- hour ozone NAAQS , 24

- hour and annual PM 2.5 NAAQS , and for the regional haze program

. It is not a procedures document that comprehensively cover s the methods for compiling and documenting emissions inventories

. Fu rthermore, th e predecessors to th is guidance have historically relied on separate guidance documents
to a dd information for various specific purposes

. In Section 2.3 , we list the various inventory components needed for 8

- hour ozone, PM 2.5 , and regional haze implementation and identify the associated sections of this guidance and o ther relevant guidance materi als.
In addition to this guidance, the “ Guidance on the Use of Models and Other Analyses for Demonstrating Attainment for Air Quality Goals for Ozone, PM 2.5 , and Regional Haze ” ( http://www3 .epa.go v/ttn/ scram/guidance_sip.htm ) , or “Modeling Guidance”, covers the creation of emissions inventories for use in air quality modeling

. These modeling inventories differ from the inventories covered in this document in that th ey usually have a larger spatial extent (i.e., a multi

- state area as opposed to just the nonattainment area or individual state ) and require extra processing steps to obtain the spatial and temporal resolution of the air quality model input species

. To the extent the Modeling Guidance covers future

- year emissions, efforts have been made to harmonize the future

- year guidance in that Guidance with the information included in Section 5 of this document.

In accordance with 40 CFR Su bpart A Section 51.5(b), states are urged to use applicable, state

- of

- the art techniques for estimating emissions. A number of inventory development resources are available from the EPA for use by air agencies for estimating base year emissions inventories

. Table 1 provides these references and a brief description of how they can be used

. More information on how these resources can be applied is provided in Section s 4 and 5

.

Table 1 : List of EPA estimation resources for emissions inventories
Resource and website Description National Emissions Inventory (NEI) ( www.epa.gov/air

- emissions

inven tories ) Summaries of the latest NEI data and documentation are available from links provided at this website

. More detailed data are available to air agencies from the Emission s Inventory System (EIS)

.

Emission Factors used for the National Emissions Inv entory (NEI) λ ( www.epa.gov/air

- emissions

inventories/national

- emissions

inventory l ) The National Emissions Inventory (NEI) program provides emissions estimation tools (that incl ude emission factors) and point

- source emission factors based on EPA rule development efforts. In many cases, these factors are more recent than those in WebFire and AP

- 42, and agencies are encouraged to rely on these where available. Emissions Inventory System ( www.epa.gov/air

- emissions

inventories/emission

- inventory

- system

eis

- gateway ) The EIS allows for summaries and extraction of detailed data for use by air agencies . The EIS allows both state

- submitted as well as the composite EPA

state data used for the NEI to be queried andEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

3 Resource and website Description downloaded

. Training on reports is also available, and Appendix A provides an EIS quick reference for county and facility reports.

Local

- scale emissions inventory development ( www.epa.gov/air

emissions

- inventories/local

- scale

emission

- inventory

- development ) In 2010, the EPA completed a project to assess the building of multi

- pollutant inventories at the scale of nonattainment areas. A project descri ption and the final report are available; the latter documents the recommended actions for state and local agencies that want to develop local

- scale emissions inventories , including SIP planning inventories

.
Electric Generating Unit emissions data from Co ntinuous Emissions Monitor ing Systems (CEMS ) ∆ ( ampd.epa.gov/ampd ) Carbon dioxide ( CO 2 ) , nitrogen oxides ( NO X ) , sulfur dioxide ( SO 2 ) , and heat input data from Electric Generating Units ( EGUs ) collected by the EPA

. He at input data can be used to estimate hourly emissions of other pollutants using emission factors.

Emissions I nventory Improvement Program (EIIP) Documentation, Volumes 1

- 9. ( www.epa.gov/air

- emissions

inventories/emission

- inventory

improvement

- program
- eiip ) Emissions estimation procedures for point, area (nonpoint) and mobile sources. While much of the information included in these reports is still rel evant, t he EIIP documentation for point and nonpoint sources has some outdated parts , and the sections below indicate some of those limitations and alternative resources. The EIIP documentation for mobile sources (volume 4) is out of date because it refers to previous versions of EPA emissions models. Use more current resources, listed below for mobile sources and fires. While EIIP is also out of date for biogenic sources, these sources are relevant only for modeling inventories and not for the inventories covered by this guidance.

Emission Factors

– WebFire ( www 3 .epa.gov/ttn/chief/webfire/ ) and AP

- 42 ( www 3 .epa.gov/ttn/chief/ap42 ) Emission factors are use d to estimate emissions, generally by multiplying by some activity value for that emissions activity , where no better method of emissions quantification or estimation is available

. AP

42 is not an appropriate source of emission factors for mobile sources o ther than road dust. General Principles for the 5

- Year Regional Haze Progress Reports for the Initial Regional Haze State Implementation Plans ( https:// www.epa.gov/visibility/general

principles

- 5

- year
- regional

- haze

progress
- reports ) This document has been developed by the EPA for the EPA Regional office s and states in preparing and reviewing the 5

- year progress reports for the initial Regional Haze SIP s . This document summarizes and clarifies the requirements for the first 5

- year reports, including emissions inventory aspects.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

4 Resource and website Description Motor Vehicle Emissions System (MOVES) ( www 3 .epa.gov/otaq/ models/moves/ ) The model, technical documentation, and guidance on the use and application of the MOVES model for on
road and nonroad mobile sources.

Mobile sources Policy and Guidance ( www 3 .epa.gov/otaq/ sta teresources/policy/ ) Webpage that provides state and local agencies with direction on how to implement strategies fo r controlling emissions from mobile sources

. Includes links to guidance documents that describe process for securing SIP air quality credit s for voluntary and innovative emission reduction programs

. See also link to nonroad documentation now available from the MOVES page. Transportation Conformity ( www 3 .epa.gov/otaq/ stateresources/transconf/ ) General information, policy and technical guidance about transportation conformity

.
λ F rom this main web page, obtain factors using the link to the latest available NE I or NEI Plan

. ∆ Select “Data Sets and Published Reports”

.
M any other resources from other organizations exist. Where specific methods or tools from non

- EPA organizations are included in this documentation, this document includes relevant references for th ose materials to help readers find these additional sources of information.
In addition to base year emissions, emissions projections are needed for a variety of reasons, including redesignation maintenance plans, the attainment projected inventory for a n onattainment area (NAA) , air quality modeling for a ttainment plans , and projecting reasonable progress goals for visibility improvement as part of Regional Haze SIP s

. In Section 5 , this guidance provides information on methods for emissions projections

. The EPA provides emissions projections data and documentation as part of its modeling platforms that are available at the Emissions Modeling Clearinghouse ( https://www.epa .gov/air

- emissions

- modeling )

. On

- road and nonroad mobile source projections are covered in the mobile regulatory documentation associated with MOVES ( https://www3.epa.gov/otaq/models/moves/ )

. Ad ditional n onroad mobile projections information (for aircraft, commercial marine vessels, and locomotives) are included as part of this documentation in the

n onroad mobile sources part of Section 5

. 

### 1.3 Summary of Relevant Statutor y Provisions
N umerous sections of the CAA apply to the implementation of emissions inventory requirements

. This section provides a brief synopsis of some of those sections that may be relevant for reference in later sections of this guidance

. All of the se ctions below are a part of CAA Title I

– Programs and Activities.

 Section 110(a) describes the basic requirements for SIPs , which provide for implementation, maintenance, and enforcement of the NAAQS

. o Section 110(a)(1) specifies parameters for infrastruct ure SIPs

. GeneralEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

5 o Section 110(a)(2) specifies a “notice and public hearing” 4 process is needed.

o Section 110(a)(2)(F) specifies that infrastructure SIPs shall require, as may be prescribed by the EPA Administrator, “periodic reports on the nature and

amou nts of emissions and emissions

- related data” from stationary sources.

o Section 110(a)(2)(K) requires infrastructure SIPs to provide for air quality modeling as determined necessary by the Administrator and allows the EPA to require the submission upon reque st of data related to that air quality modeling.

o Section 110(a)(2)(J) addresses requirements related to Part C of the CAA, related to prevention of significant deterioration and visibility protection.

Readers should refer to the “Guidance on Infrastructur e State Implementation Plan (SIP) Elements under Clean Air Act Sections 110(a)(1) and 110(a)(2); September 2013; www3.epa.gov/airquality/urbanair/sipstatus/infrastructure .html

. General

 Section 110(p) requires states to submit “reports” according to the Administrator’s schedule, “relating to emissions reductions, vehicle miles traveled, congestion levels, or any other information the Administrator may deem necessary to as sess the development effectiveness, need for revision, or implementation of any plan or plan revision” for a SIP. General

 Section s 169 A and 169B focus on visibility protection for Feder al class I areas and require the EPA to promulgate regulations estab lishing requirements for implementation plans to assure reasonable progress towards improving visibility

. To do this, the EPA has codified the regional haze program requirements in 40 CFR 51.308 and 51.309

. Regional Haze

 Section 172(c)(3) in Part D, Subp art 1 describes NAA SIP requirements for all criteria air pollutants (CAPs)

– carbon monoxide (CO) , lead (Pb) , nitrogen dioxide (NO 2 ) , ozone, particulate matter (PM) , and SO 2 – that, unless superseded by subsequent NAAQS

- specific subparts, apply to SIPs fo r NAA s submitted to the EPA

. This section includes a requirement that such SIPs include a current inventory of actual emissions in a NAA

. It allows the EPA Administrator to require periodic updates needed to determine if the general requirements of nonatta inment SIPs (i.e., Subpart 1) are met. General

 Section 175A describes maintenance plans, which are SIP revisions that provide for the maintenance for 10 years of any primary NAA QS for which an area has been redesignated to attainment and may include addi tional control measures necessary General

4 Public hearings are explained at 40 CFR 51.102(a).Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

6 to ensure this maintenance. U pdated emissions inventories are to be included in a maintenance plan.

 Section 182(a)

- (f ) provide SIP inventory requirements for all areas designated as nonattainment for the ozone N AAQS.

o Section 182 (a) includes SIP requirements for ozone NAAs classified as Marginal and above.

 Section 182(a)(1) requires a current and comprehensive inventory of actual emissions of all sources of ozone precursors to be included in a SIP

.

 Section 182(a)( 3) (A) requires periodic inventories to be provided by a state to EPA, until an area is redesignated to attainment , no later than the end of each 3

- year period after the submission of the inventory for 182(a)(1).

 Section 182(a)(3) (B) requires areas to inclu de in their SIP a requirement for stationary sources of NO X and volatile organic compounds (VOC) to provide the state with a n annual statement showing actual emissions of NO X and VOC.

o Section 182(b) includes SIP requirements for ozone NAAs classified as Mo derate and above.

 Section 182(b)(1)(A) requires a rate of progress (ROP) demonstration, and describes requirements for annual reductions in VOC and NO X emissions as necessary to attain the ozone NAAQS.

 Section 182(b)(1)(B) requires a baseline emissions in ventory for NO X and VOC from all anthropogenic sources in the NAA to be included in ozone SIPs for purposes of ROP/ reasonable further progress ( RFP ) demonstrations

. o Section 182(c) includes SIP requirements for ozone NAAs classified as Serious and above. T his section defines major sources for areas classified as Serious as sources that emit or have the potential to emit at least 50 tons of VOC per year.

 Section 182(c)(2)(A) requires an attainment demonstration based on photochemical modeling. A modeling inv entory is needed for the attainment demonstration analysis.

 Section 182(c)(2)(B) requires a RFP demonstration, and describes requirements for a timeline of VOC emissions reductions. RFP demonstrations must include baseline emissions for comparison against the emissions reductions.

o Section 182(d) defines major sources for areas classified as Severe as sources that emit or have the potential to emit at least 25 tons of VOC per year. OzoneEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

7 o Section 182(e) defines major sources for areas classified as Extreme as sources that emit or have the potential to emit at least 10 tons of VOC per year.

o Section 182(f) provides that all major source CAA requirements for VOC also apply for NO X unless a waiver is received.

 Section 182(j) (1) requires states in a multi

- state ozone NAA to take all reasonable steps to coordinate, substantively and procedurally, the revisions and implementation of SIPs for a multi

- state ozone NAA.

 Section 184(b)(2) defines major sources for areas within the ozone transport region (OTR) as any sta tionary source that emits, or has the potential to emit, 50 tons per year of VOC. Per the requirement for Section 182(f), this definition also applies to sources of NOx. Ozone

 Section 189(a)(2) in Part D, Subpart 4 provides a different and earlier schedu le (18 months rather than 3 years) for PM SIPs than provided for in the general provision in Part D, Subpart 1. PM 2.5

 Section 189(b)(3) (also Part D, Subpart 4) defines major sources in Serious PM NAAs as sources that emit 70 tons per year of PM 10 . Inven tories for PM SIPs for Serious NAAs should establish the inventory of major point sources using the lower threshold

. This section of the CAA has be en determined through the courts to be the appropriate governing section for PM 2.5 implementation as well as PM 10 . PM 2.5

It is important to note the distinction between a requirement in the CAA that an inventory be a SIP submission or included in a SIP submission, a requirement that a state’s SIP provide for the preparation and submission to EPA of an invento ry or other emissions information, and a requirement that a SIP demonstrate some fact (such that a NAAQS will be attained by a future date) that can only be established by using sound emission inventory information in an appropriate manner. This distinctio n is important because if an inventory is a required SIP submission , then certain procedural requirements apply . Inventories that are SIP submissions , or included in SIP submissions , must comply with all procedural requirements that are applicable to any o ther SIP submission including but not necessarily limited to those specified CAA section 110 and 40 CFR 51.102, 103 and Appendix V. This document clarifies which emission inventories are required SIP submissions and which are not.



### 1.4 Summary of Guidance Conte nts T his guidance document will define parts of and considerations for emissions inventories to meet SIP requirements for complying with the 8

- hour ozone NAAQS, the PM 2.5 NAAQS (2 4

- hour and annual), and the regional haze regulations

. Section 2 p rovide s an overview of the creation, documentation, and submission of the planning inventories

. Section 3 has subsections for each of the separate inventory requirements or recommendations, with details provided for all requirements excep t the base year andEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

8 projected emissions inventories

. Section s 4 and 5 provide the detailed guidance on developing base year emissions inventories and projected emissions inventories, respectively

.



## 2 S IP Inventory Overview There are two categories of emissions inventories associated with SIP development: planning inventories and modeling inventories

. Modeling inventories are used for modeled attainment demonstrations and setting reasonable progress goal s for visibility protection

. Planning inventories are needed for ozone and PM 2.5 SIPs to quantify nonattainment area emissions, and they are used as a part of RFP analysis and transportation conformity

. The primary focus of this guidance is the planning in ventories, whereas the modeling inventories are primarily addressed in the modeling guidance that is provided separately in the Modeling Guidance document ( see Section 1.2 )

. Generally, the EPA recommends that the planning inve ntories and modeling inventories be consistent, though there are exceptions. The exceptions are noted where they arise throughout this guidance and the Modeling Guidance ; however, the EPA generally encourages air agencies to minimize inconsistencies where possible

. The many aspects of p lanning inventories are covered more thoroughly in Section 3

. These aspects include the timing for submitting the various inventory components, the inventory preparation plan (IPP) , the base year NAA inventory, the RFP baseline inventory, the ozone periodic inventory, the ozone emissions statement requirement for SIPs, the maintenance inventor ies , the attainment projected inventory for the NAA , public hearings, and inventory approval by the EPA

.
I n this section, we provide an overview of the creation, documentation, and submission of the planning inventories

. Section 2.1 lists the various steps associated with building the planning inventory parts of a SIP and identifie s the relevant sections of this document that address those s t eps

. The discussions between air agencies and the EPA regarding the inventory approval process is described in Section 2.2

. In Section 2.3 , we list all of the required inventory components, including modeling inventories that are needed for ozone, PM 2.5 , or r egional h aze , but otherwise defer to the M odeling G uidance for the factors for air agencies to consider in building those inventories

. In Sections 2.4 and 2.5 , we describe other federal emissions reporting requirements that are r elevant to NAAQS implementation and provide definitions of key terms needed to understand, develop, an d submit emissions inventories for SIPs.



### 2.1 Recommended Steps for Building the Inventory Part s of a SIP Throughout this document, we describe many technical components that c ould be included in inventories in a SIP for ozone, PM 2.5 , or regional haze implemen tation

. Before air agencies start to create those components, it is important to recognize that there is a process associated with building them

. This section describes the process agencies should undertake for a successful inventory development and submit tal effort

. The inventory development process involves both required and optional steps

. Some optional steps may be take n by the air agency if it believe s it is in its best interest to do so, and optional steps can alsoEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

9 become critical to a particular SIP development process and identified as such by an EPA Regional office

. Thus, a fundamental part of the process is establishing and maintaining open lines of communication between the air agency and the respective Regional office . The Regional office should be viewed by the air agency as the typical starting point for questions related to planning and modeling inventory development, and the Regional office staff will direct questions needing EPA headquarters input as they arise

. A key aspect of this guidance is identifying opportunities for states to leverage existing work to help them meet the implementation requirements. This starts in Section 2.4 with a description of how work done in support of the NEI can be helpful for the S IP inventory work.

Table 2 provides a list of steps for completing the planning inventory and related parts of a SIP

. The list is provided in groups of steps that occur in phases presented roughly in chronological order

. The seco nd column of the table indicates the section(s) of this document th at give more information on the particular step. States and Regional office s should look for opportunities to be efficient where possible to reduce workload. For example:

 a n Inventory Prepa ration Plan for an air agency that has prepared emission inventory SIPs for a given NAAQS may not be needed, could reference a past plan, or could need fewer details;

 c ombining documentation from separate steps into a single document where that makes sens e; and

 r eferencing externally provided inventory documentation where externally prepared emissions data have been used in the SIP inventory is acceptable (in this case, the air agency would just explain why the externally prepared data are applicable for t he SIP inventory).

Table 2 : Steps for b uilding the i nventory p art s of a SIP

Inventory

- related SIP development step Document section Planning

 Review this guidance

. All

 Become familiar with inventory development resources

. 1.1 1.2

 During development of the Inventory Preparation Plan , clarify and discuss the inventory approval process that your Regional office will use , including all requirem ents, reporting formats and elements to be included, timing, and technical documentation contents

. 2.2 (general) 3.1 (timing)

 Understand required and potentially req uired inventory components for the SIP

. Determine which inventories must be created for your SIP. 2.3

 Understand inventory definitions and data requirements

. 2.5

 Un derstand timing requirements of submitted components

. 3.1

 Prepare and finalize the Inventory Preparation Plan

. 3.2

 Prepare a q uality assurance project plan (QAPP) 3 .2Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

10 Inventory

- related SIP development step Document section

 Understand requirements and choose key inventory features, including inventory year (s) , the pollutants and precursors to be included, and priority emissions

sources

. 4
Creating Inventories

 Assess what inv entories already exist that can be used as a starting point

. 2.4 3.3

 Create base

- year planning inventories

. 4

 Quality assure and refine base year inventory data in accordance with the IPP and QAPP

. 0

 Create projected planning emission inventor ies

. 5

 Quality assure and refine projected planning emis sion inventories in accordance with the IPP and QAPP. 5.5 Preparing Documentation

 Review requirements with respective Regional office in light of the particular challenges associated with a given SIP development process, suc h a first nonattainment SIP development for a state, area, or air agency staff

. 2.2

 Prepare documentation

. 3.10 Public Hearings 3.9 Submit to the EPA for Approval 3.10



### 2.2 Discuss the Inventory Approval Process with EPA Early in the SIP planning process, air agencies should discuss the emissions inventory approval process for tha t specific SIP with their respective EPA Regional office

. T hese discussion s should address the tangible items (e.g., reports, data files, summary spreadsheets) that will be delivered to the EPA as necessary to support the EPA’s review and approval

.
A comm on source of confusion is whether inventories must undergo public review. Inventories that are SIP submission s , or are included in SIP submissions, must comply with all procedural requirements that are applicable to any other SIP submission including but n ot necessarily limited to those specified in CAA section 110 and 40 CFR 51.102, 103 and Appendix V. Details on t h e public review issue are addressed in more detail in Section 3.9

. As new issues arise during the SIP development process, air agencies or the EPA Regional office s may need to reassess the previously discussed inventory approval process

. Both agencies should be aware of possible changes that are needed as the inventory development process occurs, and either party shou ld raise concerns about the need for discussion and possible revision of the process

. Details of the process and documentation can be modified through additional discussions as the need arises

. As t he inventory development process works far better when lin es of communication remain open, the EPA encourages periodic coordination meetings or check

- ins during the inventory development periods.

Table 3 provides a list of tangible reports, summaries, and data files that could be include d as part of the inventory efforts for SIPs

. S ome of these items are needed to meet statutory and/or regulatoryEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

11 requirements , and these are listed in Tables 4 through 6 below

. T he form of reports, summaries , and data files to be included should be clarifie d with the Regional office at the start of the inventory development process for SIPs

. States should discuss and confirm with the EPA Regional office the items to be included in the SIP to avoid inadvertent omission of items required for approval of the in ventory parts of the SIP. While certain recommended items in Table 3 are not specifically required by the regulations, the EPA review of the required elements requires supporting documentation so that the EPA can assess whether the approaches used for deve loping inventories are technically sufficient and meet the requirements to use appropriate methods and current, accurate information.
One notable and important difference between regional haze and the other two programs (ozone attainment SIPs and PM2.5 att ainment SIPs) is that the re is no requirement to submit detailed emissions inventory data as an element of a required Regional Haze SIP

. While the regional haze program expects that inventories will be used to accomplish the required elements of the Region al Haze SIP and the regional haze regulations require the SIP to provide for the preparation of emission inventories for particular timeframes , 5 the detailed emissions inventory data are not submitted as a SIP (or SIP revision) like the data must be for oz one and PM 2.5 . The recommended items in Table 3, however, will allow the EPA to make a determination whether the emissions information used in Regional Haze analysis is sufficient for the purposes of the SIP.
Following receipt of an emissions inventory fro m air agencies, the EPA will determine if it is part of a SIP submission or not. If an emissions inventory is provided to the EPA as a component of a SIP submittal, then EPA will process that SIP submittal, including the emissions inventory component, in a ccordance with a pplicable laws and regulations ( FN : CAA section 110 and 40 CFR 51.102, 103 and Appendix V ) . As an example, emissions inventories required by CAA § 182(a)(1) are to be provi ded to EPA as a SIP submission ( FN : See 80 FR 12264,12291) . Converse ly, if an emissions inventory is provided to the EPA outside of a SIP submittal, then EPA will review and process that inventory as necessary.

5 See 40 CFR 51.308(d)(4)(v) (Regional Haze SIPs must “provide for” statewide emissions inventories of pollutants that are re asonably anticipated to cause or contribute to visibility impairment in any mandatory Class I Federal area.). The proposed amendments to the Regional Haze Rule would similarly require state’s Regional Haze SIPs for the second and subsequent implementation periods to provide for such emissions inventories. Protection of Visibility: Amendments to Requirements for State Plans; Proposed Rule (81 FR 26942, May 4, 2016)

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

12 Table 3 : Recommended i tems to include in i nventory information provided to the EPA

Inve ntory Item Ozone PM 2.5 Regional Haze Planning Inventories Inventory Preparation Plan X X X Emissions Inventory Report, with explanations of methods, quality assurance and emissions summaries

. All inventories can be inc luded in such a report, including b ase year and projected inventories

. The inventories to be included depend on the NAAQS , the nonattainment classification, and the stage of implementation (initial SIP, redesignation, etc.)

. X X

Emissions Inventory Report, with explanations of methods, q uality assurance and emissions summaries

. All inventories can be inc luded in such a report, including base year, most recent year, and projected inventories

. X

Tables or s preadsheets of emissions summaries included in the inventory report X X X

Detai led emissions inventory files, databases, or spreadsheets X X Modeling Inventories Modeling Demonstration Report

– The emissions information can

be a section in a larger report or could have its own report

. The content should i nclude methods, quality ass urance, and emissions summaries for the modeling inventories, including projected inventories

. A statewide emissions summary is needed, and this can be included in the planning inventory SIP for convenience. X X X

Tables or s preadsheet summaries of emiss ions inventory used for modeling X X X Detailed emissions inventory files, databases, or spreadsheets X X Detailed data about emissions controls used to model X X Other Emission Statement SIP showing the state’s program to require

sources to submit emissions statements annually X



### 2.3 Planning and Modeling Inventory Components
T he ozone, PM 2.5 , or regional haze implementation rules ha ve specific inventory requirements for SIPs to

su pport attainment, maintenance , and/or reasonable progress demonstratio ns

. Additionally, there are possible inventory details that could be required or advisable for various reasons

. One major distinction between the inventory requirements of the o zone and PM 2.5 r ules versus the proposed Regional Haze R ule is that the form er two rules require inventories for NAAs , while the latter expects that states develop statewide inventories

. This section provides a list for each of the three rules for the required and possible inventory components of SIPs , with additional details for the types of planning inventories

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

13 2.3.1 Ozone SIP Inventory Components T he Ozone Implementation Rule (40 CFR p art 51, Subpart AA ) provide s the regulatory requirements for inventories of actual emissions that support ozone NAAQS implementation by air agencies

. In Table 4 below, we list the inventory components that could be part of preparing an ozone SIP and identify the governing portion of the CAA for required SIP elements, rule citation and deadline for required SIP elements and the appl icable guidance in which they are addressed

. The deadlines are expressed in months after the effective date of designation (EDD) of the area.

St ate s and other air agencies that perform modeled attainment demonstrations should also refer to the Modeling Gui dance ( http://www3.epa.gov/ttn/scram/guidance_sip.htm ) , which includes a section on emissions inventories for modeling

. As part of that guidance, emissions inventory summaries are described for inclusion in technical documentation about the modeled attainment demonstration

. To assist the public when it comments on the SIP submittal and to facilitate EPA review of the SIP submissions , these summaries of modeling inventories can be submitted as pa rt of the documentation provided with the emissions inventory SIP , but are not required SIP elements

.
Table 4 : Ozone SIP emissions inventory components
Inventory Component Required by CAA ? (CAA Section) Regulatory Citation

(Due Date ) Guidance Sections and/or Document(s) Inventory Preparation Plan This document, Section 3.2 Base year inventory for the NAA Yes 182(a)(1) 40 CFR 51.1115(a)

( 24 months after EDD ) This document, Section 3.3 and Section 4 ROP/ RFP baseline NAA inventory (part of the ROP/ RFP plan (s) ; for Moderate and above areas) Moderate & above: 182(b)(1)(B) Serious & above: 182(c)(2) (B) 40 CFR 51.915

40 CFR 51.1110(b) (36 months after EDD) This document, Section 3.4 and Section 4

Periodic NAA inventory Yes 182(a)(3) 40 CFR 51.915

40 CFR 51.1115( b) (No later than the end of each 3

- year period after required base year submission) This document, Section 3.5

and Section 4

Attainment p rojected inventory for the NAA + Summary required by 40 CFR 51.114 (b) This document, Section 3.8

and Section 5 Maintenance NAA inventory Yes ‡ 175A(a) This document, Section 3.7 and Section 4 Source Emission Statements requirement for SIPs Yes 182(a)(3)(B) 40 CFR 51.915

(24 months after EDD) This document, Section 3.6

Inventories for modeled attainment demonstrations (base and projected attainment year) Yes ∆ 182(c)(2)(A) 40 CFR 51.908

40 CFR 51.1108 (Timing depends on nonattainment classification) See the Modeling Guidance

.

Summaries of inventories (base and projected attainment year) are encouraged to be incl uded in technical documentation.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

14 Inventory Component Required by CAA ? (CAA Section) Regulatory Citation

(Due Date ) Guidance Sections and/or Document(s) Public hearing requirement for SIP inventories Yes 110(a)( 2 ) 40 CFR 51.102 This document, Section 3.9 Planning inventory documentation This document, Section 3.10

+ If this inventory is the mechanism by which the ROP/RFP plan requirements will show the emissions reducti ons required for ROP/RFP, then this inventory or its summary would necessarily become part of the ROP/RFP plan(s). Motor vehicle emissions budgets for purposes of transportation conformity are the on

- road portion of the projected emissions associated with the ROP/RFP plan.
‡ Maintenance NAA inventories are only associated with maintenance SIPs rather than attainment demonstration SIPs.

∆ While modeling inventories are not an explicit requirement of the CAA, it is presumed here that state s would not be a ble to perform credible modeled attainment demonstrations without modeling inventories.

2.3.2 Annual and 24

- Hour PM 2.5 SIP Inventory Component s The PM 2.5 SIP Requirements Rule (40 CFR p art 51, Subpart Z) provides the regulatory requirements for inventories of actual emissions that support PM 2.5 NAAQS implementation by s tate, local, and tribal agencies

. In Table 5 below, we list the inventory components that could be part of a PM 2.5 SIP and provide a map to the governing portion of the CAA , regulation s , and the applicable guidance

. For areas that perform modeled attainment demonstrations, please also refer to the Modeling Guidance , which includes a section on emissions inventories for modeling

. As part of that guidance, summaries are described for statewide inventories

. For convenience, these su mmaries can be included in the emissions inventory SIP

. Areas that do not perform modeled attainment demonstrations would not need to provide the statewide inventories for PM 2.5 .
Table 5 : PM 2.5 SIP emissions inventory components

In ventory Component Required by CAA? (CAA Section) Regulatory Citation

(Due Date) Guidance Sections

and/or Document(s)
Inventory Preparation Plan This document, Section 3.2

Base year inventory for the NAA Ye s 172(c)(3) Moderate

40 CFR 51.1008(a)(1) α ( 18 months after EDD) This document, Section 3.3 and Section 4
Attainment projected inventory for the NAA Moderate: 40 CFR 51.1008(a)(2) α ( 18 months after EDD) T his document, Section 3.8 and Section 5

Maintenance NAA inventory Yes + 175A(a) This document, Section 3.7 and Section 4

Inventories for modeled attainment demonstrations (base year and projected attainment year) Yes ∆ 189(a)(1) for Moderate areas and 189(b)(1) for Serious areas 40 CFR 51.1001 and

Appendix W (18 months after EDD) Modeling Guidance

. Summaries of statewide inventories (base and projected atta inment year) are encouraged toEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

15 In ventory Component Required by CAA? (CAA Section) Regulatory Citation

(Due Date) Guidance Sections

and/or Document(s)
be included in technical documentation. Public hearing requirement for SIP inventories Yes 110(a)(2) 40 CFR 51.102 This document, Section 3.9 Planning inventory documentation T his document, Section 3.10

α If an area is reclassified as Serious, the applicable requirements refer back to this subsection from 40 CFR 51.1008(b)

. If a Serious area has failed to meet the PM 2.5 NAAQS by the Serious area attainment date, then see 40 CFR 51.1008(c), which still ref ers back to the Moderate area requirements and has a 12 month deadline.

+ Maintenance NAA inventories are only associated with maintenance SIPs rather than attainment demonstration SIPs.
∆ While modeling inventories are not an explicit requirement of the CAA, it is presumed here that state s would not be able to perform credible modeling attainment demonstrations without modeling inventories.

2.3.3 Regional Haze SIP Inventory Components The Regional Haze Rule (40 CFR p art 51 , Subpart P ) has significantly differen t inventory requirements from ozone and PM 2.5 implementation rules. One reason for this differen ce is the time horizon of the regional haze program

. The program consists of implementation periods that are referred to as the first planning period, second pl anning period and so forth. There are parts of regional haze implementation plans that have been completed via the SIP for the first implementation period (ending in 2018) and may not need to be revisited in SIPs for later implementation periods , but for c ompleteness we also explain these here. Another difference is that the Regional Haze Rule requires the use of statewide planning inventories rather than inventories for only a smaller NAA. Finally, the most important difference is that there is no requirem ent that emission inventories be submitted as a SIP revision . While the inventories are needed to support the SIP and the SIP must provide for the specified emission inventory information , the detailed statewide inventories need not be submitted.

As noted above, the EPA proposed changes to the Regional Haze Rule in May 2016. 6 If finalized, these changes would apply only for the second and subsequent planning periods; requirements for the first planning period are governed by the existing Regional Haze Rule. This section briefly discusses the existing requirements related to emission inventories for the first planning period, and then goes on to address the same requirements as proposed for the second and subsequent planning periods.
For the first planning pe riod, the Regional Haze Rule in 40 CFR 51.308(d)(3)(iii) required a SIP submission to include the technical basis on which the State was relying to determine its apportionment of emission reduction obligations necessary to achieve reasonable progress towar ds natural visibility conditions , includ ing identification of the “ baseline emissions inventory ” used for such technical analysis. The rule indicated that the baseline emissions inventory year for the first planning period is presumed to be the
most recent year of the consolidated periodic emissions inventory (as defined in Subpart A and commonly called the NEI). As a result, this “baseline” inventory used in the SIPs reflect s a year from the 2000

- 2004, for which the 2002 was the applicable NEI year. For th e first planning period, most states

6 Protection of Visibility: Amendments to Requirements for State Plans; Proposed Rule (81 FR 26942, May 4, 2016).Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

16 also used a year from this period as the base year for their regional air quality modeling ( s tates that were members of the Lake Michigan Air Directors Consortium ( LADCO ) also used 2005 in their air quality modeling )

.
I n addition, 40 CFR 51.308(d)(4)(v) required that the plan provide for a statewide inventory of emissions for a “baseline” year , for the most recent year in which data are available (“recent year”) , and estimates of future projected emissions

. This section made it clear that the inventories associated with the planning effort needed to be “statewide

. ” This document does not explain in detail the emission inventory requirements for SIPs for the first implementation period, which have already been submitted

an d acted upon by the EPA.
The regional haze rule at present also includes a requirement f or 5

- year progress reports in 40 CFR 51.308(g) . The initial 5

- year progress report (for the first planning period) is required to be a SIP revision

. 7 Because many of t he first of these required 5

- year progress report SIP revisions have already been submitted and the remaining progress reports should be far along in preparation as of the date of this document, this document does not address the first

- required progress re ports. For guidance on these first required 5

- year progress reports, readers should use the separate guidance document

“ General Principles for the 5

- Year Regional Haze Progress Reports for the Initial Regional Haze State Implementation Plans

. ”

The EPA has proposed to revise the Regional Haze Rule so that the next required progress report would be due on January 31, 2025. Thereafter, progress reports would be due midway between “10

- year” SIP revisions, with due dates of July 31 of 2033, 2043, etc. Under the proposed revisions, these future periodic progress reports would not be required to be SIP revisions. S ection 308 (g)(4) , as it would be amended under t he proposed revisions, requires states to analyze the change in emissions over the period since the previous plan revision (i.e., the SIP revisions due in 2021, 2028, and every 10 years thereafter ). The requirement sets out that “ [e] missions changes should be identified by type of source or activity , ” and this guidance provides recommendations for what emissions summaries these reports should include to accomplish that objective. In addition, the proposed Regional Haze rule revisions specify that the analys is of historical emissions must extend at least through the most recent year for which the state has submitted emission inventory information to the EPA in compliance with the triennial reporting requirement of the Air Emissions Reporting Rule (AERR), 40 C FR part 51, Subpart A

. For data (such as EGU data) that are submitted directly to the EPA and then made available by EPA, the data used must be the most recent year for which the EPA has provided state

- level summary data or an internet

- based tool by which the State may obtain such a summary . Further, section (g)(5) as amended would require an assessment of any significant changes in anthropogenic emissions within or outside the state that have occurred since the previous SIP revision

.
Section 40 CFR 51.308( f) of t he Regional Haze Rule require s 10

- year SIP revisions for the second and subsequent implementation periods ; EPA proposed revisions to the requirements for SIP revisions in

7 On May 4, 2016, the US EPA proposed amendments to the regulatory requirements for the Regional Haze SIPs that included a proposed change such that the 5 year progress reports would no longer be a SIP revision.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

17 May 2016. As it would be revised, section 308(f)(2) specifies that the SIP rev ision include a long

- term strategy and section (f)(2)(iv) requires that the state document the technical basis for its determinations of the emission reductions from anthropogenic sources that are necessary for achieving reasonable progress towards natural visibility conditions. The proposed wording in this section requires that a state “identify the baseline emissions inventory on which its strategies are based.” In the context of this particular provision ( 308(f) (2)(iv)) , the phrase “baseline emissions in ventory” refers to source emissions corresponding to the baseline of current on

- the

- books emission control measures, which is the starting point for consideration of any additional measures that are necessary to achieve reasonable progress . It does not ref er to the 2000

- 2004 “baseline period” that appears in other parts of section 308. In the proposed section 308(f)(2)(iv) , t he baseline emissions inventory year is further explained to mean the
most recent inventory year submitted to the EPA under the trienn ial reporting requirements of AERR or another year if justified. Thus, the term “baseline emission inventory” in this section could be the same as the “recent year” inventory.

In the proposed rule revision , s ection 308(f)(6)(v) mirror s a part of s ection 3 08(d)(4) by specif ying that SIP revisions for the second and subsequent planning periods must provide for a statewide inventory of emissions for a “baseline year,” for the most recent year in which data are available (“recent year”), and estimates of proje cted emissions. In this context, “baseline year” refers to a year in the 2000

- 2004 period. A state that has submitted statewide inventory information in its SIP revision for the first implementation period has demonstrated that its SIP does provide for the creation of this “baseline year” inventory. In its SIP revision for the second and subsequent implementation periods, a state will need to describe its process for preparing, or providing essential information for the collective preparation of, a statewid e emission inventory for the latest “recent year” and a projection inventory for the last year of the implementation period.

Table 6 summaries a list of the Regional Haze SIP emissions inventory components, including the appropriate references to the CAA, the regulations, and the relevant sections of this guidance.

Table 6 : Regional h aze SIP emissions inventory components
Inventory Component Required? (CAA Section) Regulatory Citation

(Due Date) Guidance Sections

and/or Document(s) Inventory Preparation Plan This document, Section 3.2 Baseline statewide inventory Recent year statewide inventory Projected statewide inventory (For the first planning period) Yes 169A(b) + 40 CFR

51.308( d) (4)(v) (completed) Previously completed as

part of initial Regional Haze SIP for the first planning period. 5

- year (or “periodic” as proposed in the revised Regional Haze Rule) p rogress r eport, recent year statewide inventory Yes 169A(b) + 40 CFR 51.308(g) (4)

and (5) (see guidance noted above) This document, Section

3.5.2 and Section 3.10.3

10

- year SIP revisions, baseline statewide inventory ∆ Yes 169A(b) + 40 CFR

51.308(f)(6)(v) (varied dates) May r efer to the

emissions from the first planning periodEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

18 Inventory Component Required? (CAA Section) Regulatory Citation

(Due Date) Guidance Sections

and/or Document(s) 10

- year SIP revisions,
r ecent year statewide inventory ∆ Yes 169A(b) + 40 CFR

51.308(f) (6)(v ) (varied dates) This document, Section

3.5.2 and Section 4

10

- year SIP revisions, p rojected statewide inventory ∆ Yes 169A(b) + 40 CFR

51.308(f)(6)(v) (varied dates) This document, Section

3.8 and Section 5

D ocumentat ion This document, Section 3.10

+ CAA 169A(b) provides the authority to provide guidelines to the s tates on appropriate technique s and methods to implement the v isibility protection goals in the CAA. This has been done through regulations as codified in 40 CFR 51.308 and 51.309.

∆ If modeling is done to support the 10

- year SIP revision, these are modeling inventories.



### 2.4 Other Relevant Federal Emissions Reporting Requirements The Air Emissions Reporting Rule (AERR), 40 CFR p art 51, Subpart A, requires states to provide to the EPA an nual statewide emissions inventory data, regardless of whether that state has nonattainment

areas

. This regulation requires reporting of actual emissions of CO, NO X , VOC, SO 2 , PM 2.5 , particulate matter with diameter ten microns and less ( PM 10 ) , and ammonia ( NH 3 )

. For PM 2.5 , the AERR requires states to report primary (i.e., “direct”) PM 2.5 , which is defined as the sum of filterable PM 2.5 and condensable PM. The agencies are required to report the filterable PM 2.5 and condensable PM separately where they are present from the source (see Section 4.2.1 )

. S tate s may delegate the reporting requirements to local air agencies. Tribes can also submit these data to the NEI, but are not required to do so

. These data are used by the EPA ’s Of fice of Air and Radiation ’s (OAR) Office of Air Quality Planning and Standards (OAQPS) to build the NEI, and a complete version that includes all sources of emissions (with minor exceptions) is released every 3 years.

The AERR includes both triennial and a nnual statewide reporting requirements, with more extensive reporting requirements for triennial inventory years. Triennial years for the NEI include 2011, 2014, and every 3 rd year thereafter. For the interim annual inventories, reporting is limited to emi ssions data from only the larger point sources (Type “A” sources), as defined by Appendix A of 40 CFR p art 51, Subpart A

. For th e triennial inventories, lower point source thresholds are given in Appendix A, consistent with the definition of major sources in 40 CFR p art 70 . A ll other sources of emissions must be reported as nonpoint or mobile sources on a county basis in the trienn ial submissions

. Additionally, lower point source thresholds may apply to ozone, PM 2.5 , PM 10 , and CO NAA s , depending on the area’s nonattainment classification

.
The AERR requirements are relevant for SIP planning inventory purposes in several ways

. First, the AERR and its associated EIS (data system) provide the appropriate data elements (fields to be reported) for inventories for electronic transfer to the EPA

. Second, AERR

- based inventories are often used as a starting point for SIP inventories

. Third, in some cases, AERR submissions can meet some of the inventory requirements described in this document

. Finally, the resources provided by the EPA for states to meet their AERR reporting obligations, such as emissions inventory tools and models, associatedEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

19 d ocumentation, emission factors, new emissions methods, and quality assurance approaches, can assist inventory developers when making inventories for SIP planning and modeling purposes.
As a point of clarification, air agencies must meet all relevant planni ng inventory SIP requirements regardless of the availability or use of the EPA data associated with the AERR/NEI process. While the EPA resources can be helpful to states in meeting those requirements, the SIP requirements and the associated public review and Regional office approval process are independent requirement s that must be met

. It would not be sufficient to merely point to the EPA ’s publication of the NEI as having met the SIP emissions inventory requirements

. However, it may be sufficient for a s tate to submit as a SIP revision an inventory that contains some or all of the same data as in the NEI, with sufficient justification and using the applicable public comment process.


### 2.5 Emissions I nventory Definitions Emissions inventory work requires knowled ge of many terms and codes

. In this section, we define the terms relevant to inventories that are used throughout this document

. This section also references external materials needed for obtaining definitions of all valid fields that can be used for build ing inventories, which are based on the tables used to submit data to the EPA for the AERR

. Many definitions relevant for emissions inventories are defined in the CAA or codified in the AERR and the implementation rules

. These are included here for a conve nient reference in a single location since these terms are used throughout this document. Without these definitions, the meaning of the subsequent sections would be less clear. The sample below is not intended to represent a comprehensive list of inventory related definitions

. 2.5.1 Source Category/Data C ategory Traditionally, the term “source category” has been used to identify the major types of emissions inventory groupings: stationary point sources, stationary area (or nonpoint) sources 8 , on
- road mobile

sourc es, nonroad mobile sources

. In addition, fires and biogenic sources are sometimes included as additional source categories

. In practice, some inventories have started including large moveable facilities, such as asphalt plants, in the point sources invento ry without associating them with a specific county

. Additionally, some mobile sources such as locomotives and commercial marine vessels (CMVs) are treated as nonpoint data (i.e., the formatting of it) for the purpose of reporting these data to the EPA via the EIS (see also Section 4.8.5 as well as the EIS information referenced in Table 1 )

. Similarly, because of the data format and their physical nature (i.e. , a discrete geographic location), rail yards and airports are treated as point data in the EIS

. With the advent of the EIS, the preferred term for indicating subsets of inventory data has become “data category” rather than “source category” because the groupings have much more to do with how the

8 Over time, stationar y area sources have been renamed “nonpoint” sources to avoid confusion with the air toxics regulatory term “area sources,” which are often sources that meet the criteria pollutant definition of point sources. Likewise, the term “stationary” is often ignore d in common use for both the point source and nonpoint labels.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

20 dat a are created and the data structure than the features of the actual emissions sources included in the category. For example, locomotives and commercial marine vessels are included in the nonpoint data category for inventories in the EIS , but in fa ct are n onroad mobile sources. Additionally, the EIS ushered in a new data category called “events,” which are typically wildfires or prescribed fires (agricultural fires are part of the nonpoint data category) , but in principle could include other significant, sh ort

- duration, emissions events

. 9

2.5.2 Types of Emissions: A nnual, S easonal, A ctual, Potential, and A llowable Various terms are used in this and other documents to reference various types of emissions

. Here, we provide a brief list of definitions associated with various emissions types.

Actual emissions means the emissions of a pollutant from an affected source determined by taking into account actual emission rates associated with normal source operation and actual or representative production rates (i.e., capac ity utilization and hours of operation) (40 CFR 51.491)

. This is in contrast with potential emissions or allowable emissions. These actual emissions should include emissions of a pollutant that occur during period s of startup , shutdown , and malfunction (se e Section 4.8.1). In addition, please s ee Section 4.1 for a description of selecting a year for creating actual emissions estimates.

Allowable emissions means the emissions of a pollutant from an affected source determined by t aking into account the most stringent of all applicable SIP emissions limits and the level of emissions consistent with source compliance with all f ederal requirements related to attainment and maintenance of the NAAQS and the production rate associated wi th the maximum rated capacity and hours of operation (unless the source is subject to federally enforceable limits that restrict the operating rate, or hours of operation, or both) (40 CFR 51.491)

.
Annual emissions are defined in the AERR (40 CFR 51.50) as actual emissions for a plant, point, or process that are measured or calculated to represent a calendar year. This means that annual emissions should include all emissions of the relevant sources at a facility or from a nonpoint or mobile process occurrin g during a calendar year

. In general, unless otherwise specified, annual emissions means actual emissions, as defined above

. Average season day emissions means the sum of all emissions during the applicable season divided by the number of days in that seas on. This definition is used in the context of inventories developed for SIPs associated with the 24

- hour PM 2.5 NAAQS.

Potential to emit means the maximum capacity of a stationary source to emit a pollutant under its physical and operational design (40 CFR 51.301). Also called “potential emissions,” 40 CFR 51.301 also defines this term to specif y that a ny physical or operational limitation on the capacity of the source to emit a pollutant including air pollution control equipment and restrictions on hours of operation or on

9 While the EIS is not currently configured to accept event data other than for fires, this means that the idea of an “event” could be expanded to other types of events that are not currently i nventoried because of the difficult nature and non

- routine nature of these types of emissions.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

21 the type or amount of material combusted, stored, or processed, shall be treated as part of its design if the limitation or the effect it would have on emissions is federally enforceable. Secondary emissions do not count in determining the potential to emit of a stationary source.
As described in “Potential to Emit: A Guide for Small Businesses” (EPA

- 456/B

- 98

- 003), potential to emit considers the equipment design and can also consider certain controls and limitations on the operation of the equipment. Potential emissions can be expressed as potential controlled emissions , which are the pollutant emissions while a source is operating at the maximum design capacity, a schedule of 8760 hours per year, and considering the efficiency of the contr ol equipment. In contrast, potential uncontrolled emissions are simply the pollutant emissions while the source is operating at the maximum design capacity and a schedule of 8760 hours per year without factoring in controls.
Startup, Shutdown, and Malfunct ion (SSM) emissions are emissions that occur during startup, shutdown, or malfunctions at industrial facilities. As a factual matter, the emissions rate during periods of SSM can be much larger than the emissions rates during periods of normal operating pr ocedure (that is, not during periods of SSM). However, applicable emissions limitations apply at all times, including during periods of SSM. 10 More information about the startup and shutdown emissions in the SIP inventory context is described in Sections 4.3 and 4.8.1

.
Ozone season day emissions means an average day’s emissions for a typical ozone season work weekday

. The state shall select, subject to EPA approval, the particular month(s) in the ozon e season and the day(s) in the work week to be represented, considering the conditions assumed in the development of RFP plans and/or emissions budgets for transportation conformity.

2.5.3 Duration and Timing of E missions Inventory start date means the first da y of the inventory period

. This can be used for compiling and reporting monthly or other shorter period emissions, including events.
Inventory end date means the last day of the inventory period. This can be used for compiling and reporting monthly or othe r shorter period emissions, including events.
Inventory year or Emissions year means the year for which emissions estimates are reported (40 CFR 51.50)

. See also “Emission Type” in codes Section 2.5.14

. 2.5.4 Data Elements The term d ata elements means parts of a data file that contain individual items of data

. These are also called fields or variables

. Examples of key d ata elements associated with emissions inventories include emissions; activity; emission factors; state/county identi fiers; facility, unit, and process identifiers; plant

10 On May 22, 2015, the EPA issued a final action to ensure that states have plans in place that are fully consistent with CAA and court decisions concerning SSM operations. This action included a “SIP call” that directs 36 states to correct specific SSM provisions in their SIPs. The SIP submission deadline for the states subject to this action is November 22, 2016. See http://www3 .epa.gov/airquality/urbanair/sipstatus/emissions.html for more information.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

22 names; control measure codes; and process codes

. This list is just a sample and is not intended to represent a comprehensive list of required codes (see also Section 2.5.7 ).

Note that emissions data categories (Section 2.5.1 ) are not a data element per se, but rather emissions inventory submissions usually are broken out into separate datasets for each data category

. 2.5.5 T hroughput and A ctivity Throug hput means a measurable factor or parameter that relates directly or indirectly to the emissions of an air pollution source during the period for which emissions are reported (40 CFR 51.50 ). Throughput is also called a ctivity

. Depending on the source categ ory, 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, miles travelled, or number of existing units

. Activity through put is typically the value that is multiplied against an emission factor to generate an emissions estimate. Consequently, it is important to coordinate activity used for a given emissions source with the available emission factors for that source

. 11

There a re some special types of activities always used for certain categories

. Examples for mobile sources include :

Vehicle Miles Traveled (VMT) : The number of miles travelled within a year or as an average daily value for all vehicles within a group (e.g., vehic le type, fuel type , and county). See also MOVES Technical Guidance ( http://wwws .epa.gov/otaq/models/moves/index.htm#sip ).
Vehicle population : The number of vehicles of a certain type and fuel usage within a group ( such as a county )

. Equipment population : The number of nonroad equipment units of a certain type and fuel usage within
a group ( such as a county )

. 2.5.6 Emission Factor s An emissions factor is a representative value that attempts t o relate the quantity of a pollutant released to the atmosphere with an activity associated with the release of that pollutant. These factors are usually expressed as the weight of pollutant divided by a unit weight, volume, distance, or duration of the ac tivity emitting the pollutant (e.g., kilograms of particulate emitted per megagram of coal burned). Such factors facilitate estimation of emissions from various sources of air pollution. In most cases, these factors are simply averages of all available dat a of acceptable quality, and are generally assumed to be representative of long

- term averages for all facilities in the source category (i.e., a population average). E mission factors have long been the fundamental key to developing emissions inventories fo r air quality NAAQS implementation

. More information on emission factors is available from the Clearinghouse for Inventories and Emissions Factors ( https ://www.e pa.gov /chief/ ) on the EPA website.

11 Some air agencies have raised the concern that throughput at industrial facilities is considered confidential business informatio n (CBI), however, this field is required by the AERR. Since this field is “emission data” required by the AERR, it cannot be protected as C BI under CAA section 114(c).Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

23 The general equat ion for emissions estimation is:

E = A × EF × ( 1

− ER 100

⁄ )

where:

E = emissions, A = activity total, EF = emission factor, and ER = overall emission reduction efficiency percent.

The ER term is the combination of the relevant percents related to emissions controls and rules that reduce em issions, as listed in Section 2.5.18

.
E mission factors are not limited to factors that are only represent broad national industry averages published by the EPA

. Emission factors can also be stack

- , process
- , unit

- , or facility

- specific, depending on the basis of the source test information

. Whether for a single facility or a group of facilities of the same type, it i s still considered an emission factor for the purposes of this guidance

. 2.5.7 Emissions Reporting Data E lements The Ozo ne Implementation Rule and PM 2.5 SIP Requirements Rule refer to the AERR and this guidance for information on reporting data elements

. Since the AERR is focused on emissions submitted for the annual NEI inventory, it only includes definitions for those dat a and fields that are required by the NEI
program

. F or ozone SIP inventories, ozone season day emissions are required, but are optional for reporting in accordance with the AERR. For PM SIP inventories, either or both annual or average season day emissions can be included (depending on the circumstances), but the average season day emissions are optional for reporting for AERR purposes.
The many required and optional data elements for emissions i nventories are described in Excel files called Staging Require ments

. These files are comprehensive for all of the required and optional fields that can be submitted to the EPA for SIP inventories, not only the submissions for the NEI

. The shared field list for NEI and SIP inventories help s air agencies by promoting c larity and familiarity through common data element definitions across multiple inventory requirements. The descriptions provided in those Excel files are very limited, so this document provides additional information for the most important of these fields. These spreadsheet s are available at the Emissions Inventory Training website
at https://www.epa.gov/air

- emissions

- inventories/emission

- inventory

- training using the l inks for “Training Materials” listed for each training on the page. Within the Zip file provided for the “Training Materials” links, an Excel file is available that includes “s taging r equirements ” and lists the data elements and their definitions.

Alt hough many fields in the Staging Requirements are optional for AERR reporting purposes , some of these fields can be critical for inventory development for SIPs and even the NEI

. By “ optional , ” we mean those fields that are not explicitly required by the AERR or that are not enforced during electronic reporting as needing to be provided to successfully submit the data to the EPA

. The list below identifiesEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

24 fields that are “optional” but that are strongly recommended to be included in all emissions inventories , doc umentation, and reporting as applicable for the sources in the state or NAA

. For example, control parameters are optional only because emissions controls do not exist on every unit and process in an inventory, thus the EPA cannot enforce this during electr onic reporting as a required field

. However , the control information is required by the AERR when it exists at the emissions source and should be provided for SIP inventories

. Unit Description : This field describes the unit in words. It can be invaluable i n determining incorrect source classification codes ( SCCs )

.
Unit d esign capacity : Unit design capacity means a measure of the size of a point source, based on the reported maximum continuous throughput or output capacity of the unit (40 CFR 51.50 ). Useful for boilers, this field is needed when trying to understand the cost per ton of pollutant emissions reduced associated with controls on boilers

. The cost per ton is generally higher for smaller boilers

. The design capacity can be critical in SIP planning f or insuring that good decisions are made about controls on stationary boilers and other units

. While required by the AERR, the EIS does not enforce this field as many states do not have this information available

. By including these data in SIP inventory d evelopment, states can help to further improve the data available to them for decision making as well as for consideration by the EPA

.
Control measure : This field is a unique code for the type of control device or operational measure (e.g., wet scrubber, f laring, process change, and ban ) used to reduce emissions (see 40 CFR 51.50 ). When assessing whether an emissions source can be further controlled to contribute emissions reductions needed for attainment, it is imperative to know whether there is a control measure included on a unit or
process

. The type of measure is also needed to understand whether other controls can be added. The associated data elements such as control efficiency, capture efficiency, rule effectiveness, and rule penetration are all usef ul as well for the same reasons

. These latter control parameters are also needed when calculating potential controlled emissions.
Alternative facility names or identifiers : This field c an be very useful in matching the facility with other databases, such a s the Toxics Release Inventory, the Federal Registry System, or the National Electric Energy Data System (NEEDS) database. If air agencies change their agency IDs (facility, unit, process, and release point) from one year to the next, this table can help p revent creating duplicates in the EIS and other databases.

EIS IDs : While the EIS Facility ID, Unit ID, Process ID, and Release Point ID (see Section 2.5.15 ) are not required by the AERR or for SIP inventories, it is the standa rd by which the EPA compiles and reports all point source inventories

. The EPA reports and modeling all use these EIS IDs, and so to the extent air agency databases can use these IDs in their data systems, it helps facilitate matching across the many
purpo ses for inventories.
Release Point Geographic Coordinates : As described in Section 2.5.17 , the EIS and inventories generally can have location coordinates (i.e., latitude/longitude) for a facility or at individual release point locations

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

25 2.5.8 Point S ources As defined by the AERR in 40 CFR 51.50, p oint sources are large, stationary (non

- mobile), identifiable sources of emissions that release pollutants into the atmosphere. A point source is a facility that is a major source under 40 CFR part 70 for one or more of the pollutants for which reporting is required by 40 CFR 51.15 (a)(1). This does not include the emissions of hazardous air pollutants, which are not considered in determining whether a source is a point source for ozone, PM 2.5 , and regional haze emissions inventory development and reporting. These point sources can be associated with a single point or group of points in space

. Examples of i mportant point source emissions categories include power plants, industrial boilers, p etroleum refineries, cement plant s, and other industrial plants.
According to the ozone and PM 2.5 I mplementation R ules, t he AER R governs the emissions level above which sources are inventoried as point sources

. While the AERR also requires data from state agencies for use in the NEI, the AERR emissions point source thresholds have been coordinated with the various SIP implementation rules and definitions of major sources and , therefore , they apply to all inventories provided to the EPA

. The AERR bases the e missions level on a potential to emit emissions size threshold

. Table 7 provides the potential to emit point source reporting thresholds included in the AERR

. For evaluating the potential to emit threshold , it is appropriate to us e potential controlled emissions for controlled sources

. As shown in T able 7 , special requirements apply to NAA sources, wher e even lower thresholds may apply depending upon the severity of the NAA classification

.
A ir agencies may include point sources at even lower levels in their NEI or SIP planning and modeling inventories

. The AERR thresholds simply provide a minimum requirement

. Depending on the nature of the nonattainment problem and the need to characterize smaller sources as point sources, a state m ay want to consider and the EPA Regional office s may encourage lower thresholds so air agencies can produce effective SIPs.
Type A source means a large point source with potential annual emissions of any CAP or CAP precursor greater than or equal to the co rresponding emission threshold listed in the AERR

. These sources must be reported by states every year and have higher reporting thresholds. The thresholds are not repeated in the table below because they are not relevant for the definition of point source s for SIP inventory purposes , which follow the Type B thre s holds for triennial reporting as shown below

. See Appendix A of 40 CFR p art 51, Subpart A for the Type A source thresholds.
Type B source means a point source smaller than a Type A source with potential annual emissions of any CAP or CAP precursor greater than or equal to the relevant Type B emission threshold listed in the AERR and in this section

. Type B point sources are required by the AERR to be included in a state or local inventory submission for point sources in the triennial years and are applicable to SIP planning and modeling inventories as well.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

26 Table 7 : Point source triennial reporting thresholds (potential to emit) for criteria

pollutants in the Air Emissions Reporting Rule

Pollutant Triennial NEI thresholds: potential to emit (tons/yr)

Type B sources (default) NAA sources 1 SO2

................. ≥ 100 ≥ 100 2 SO2

................. PM 2.5 (Serious) ≥ 70 3 VOC or NOx

.... ≥ 100 ≥ 100 4 VOC or NOx

.... ................................ . O 3 (Moderate within OTR) ≥ 50 + 5 VOC or NOx

.... ................................ . O 3 (Serious) ≥ 50 6 VOC or NOx

.... ................................ . O 3 (Severe) ≥ 25 7 VOC or NOx

.... ................................ . O 3 (Extreme) ≥ 10 8 VOC or NOx

.... ................................ . PM 2.5 (Serious) ≥ 70 9 VOC

................ ................................ . O 3 (within OTR) ≥ 50 + 10 CO

.................. ≥ 1000 ≥ 1000 + 11 CO

.................. ................................ . CO (all areas) ≥ 100 12 Pb

................... ≥ 0.5 * ≥ 0.5 13 PM 10 ............... ≥ 100 ≥ 100 14 PM 10 ............... ................................ . PM 10 (Serious) ≥ 70 15 PM 2.5 .............. ≥ 100 ≥ 100 16 PM 2.5 .............. ................................ . PM 2.5 (Serious) ≥ 70 17 NH 3 ................. ≥ 100 ≥ 100 18 NH 3 ................. ................................ . PM 2 .5 (Serious) ≥ 70

+ This threshold for ozone nonattainment areas is incorrectly listed in the AERR as 100 tpy

. This is not consistent with other regulations . The EPA is working to make this correction in the AERR. * The lead threshold is in actual emissi ons rather than potential to emit to be consistent with the lead monitoring rule requirements.
2.5.9 Nonpoint S ources Nonpoint sources are also called “area sources”

. 12 These sources collectively represent individual

sources of emissions that have not been invent oried as specific point or mobile sources

. These individual sources treated collectively as nonpoint sources are typically too small, numerous, or difficult to inventory using the methods for the other classes of sources

. Examples of key nonpoint sources i nclude residential combustion, institutional and commercial boilers, agricultural burning, industrial and non

industrial solvents and graphic arts, degreasing, most agricultural sources, consumer products, architectural coatings, and sources of dust includ ing roads and construction.

2.5.10 On

- road Mobile S ources On

- road mobile sources are a lso called “highway mobile sources

. ” T hese sources are the motor vehicles (e.g., automobiles, buses, trucks) traveling on local and highway roads

. A motor vehicle is any self

pr opelled vehicle used to carry people or property on a street or highway (40 CFR 51.50 )

. On

- road mobile sources should be estimated by the latest recommended on

- road mobile source models

.

12 This data category type is different from the air toxics definitional of “area sources ” as defined by CAA section 112(a)(2).Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

27 Currently, that means the MOVES model ( http://www3.epa.gov/otaq/models/moves/ ) for all states but California, and the EMFAC 13 model ( http://www.arb.ca.gov/msei/modeling.htm ) for California.

2.5.11 Nonroad Mobile S ources No nroad mobile sources are also called “off

- highway” mobile sources

. These are defined as a nonroad engine or nonroad vehicle. As per 40 CFR 51.50 , a nonroad engine is an internal combustion engine (including the fuel system) that is not used in a [ on
- road ] motor vehicle or a vehicle used solely for competition, or that is not affected by sections 111 or 202 of the CAA

. Also defined by 40 CFR 51.50 , a nonroad vehicle (rather than engine) is a vehicle that is run by a nonroad engine and that is not a [ on
road ] motor vehicle or a vehicle used solely for competition. Examples of nonroad mobile sources include aircraft, airport ground support equipment, locomotives, CMVs , construction equipment powered by an internal combustion engine , agricultural equipment power ed by an internal combustion engine , and lawn and garden engines and equipment

.
There are a variety of tools for estimating emissions from nonroad mobile sources

. The EPA develops and maintains approaches for a ircraft, locomotives, and CMVs , which are doc umented as part of the NEI program (for the latest approaches, refer to the latest NEI documentation available at http://www.epa.gov/ttn/chief/eiinformation.html )

. Starting with the MOVES2014 a version of MOVES, the MOVES model should be used for nonroad source emissions. MOVES2014a includes features not previously available in MOVES that simplify processing of emissions output and includes updated fuel input files that result in small changes in emission results. In addition, the prior tools available for nonroad emissions estimations ( NONROAD2008 and NMIM2008 ) may no longer work with current operating systems , and the EPA cannot contin ue t o provide technical support for these models. Therefore , the EPA recommends that for modeling nonroad emissions, MOVES2014a be used for all new SIP development, although state and local agencies that have already completed significant work with MOVES2014, NONROAD2008, or NMIM2008 can continue to do so to allow for timely submission of the SIP. As a general matter, a ir agencies should review and possibly update and customize the MOVES model inputs to give better emissions estimates for their state

. Unlike models for onroad emissions, the EPA does not specifical ly “approve” nonroad models. However, use of alternative models can be justified as part of a SIP submission. For example, California has previously developed and used a state

- specific approach for estimating its nonroad source emissions for SIP purposes , called OFFROAD2007 ( http://www.arb.ca.gov/msei/offroad/downloads/models/offroad2007_1215_exe.zip ) . This model has now been replaced by category

- specific methods fo r many categories (see http://www.arb.ca.gov/msei/categories.htm #offroad_motor_vehicles )

. As described by the website, the OFFROAD2007 model is still the default approach for categories not listed with newer methods on the website. Any use of such an alternative approach is subject to review by the EPA as part of the review of

13 The EMFAC model name is not an acronym. The documentation and website for EMFAC do not include a further explanation of the name.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

28 the SIP, and thus states are encouraged to coordinate with Regional office s on any use of alterna tive models.

2.5.12 Events Starting with the 2008 NEI, t he EIS introduced a new data category called “E vents, ” which are discrete and large emissions sources that individually occur over a short period of time, but which can collectively result in a significant amount of emissions

. Example events captured by this data category include naturally occurring wildfire and a managed prescribed burns

. In EIS, these data are stored as day

- specific events that can span many days for a given fire/event. More information on events data and its unique nature is available in Section 4.8.7

. 2.5.13 Biogenic S ources For the purposes of creating emissions inventories, b iogenic emissions come from natural sources

. They need to be accounted for in photochemical grid models, as many types of biogenic emissions are widespread and ubiquitous contributors to atmospheric chemistry leading to ozone and PM formation

. In the NEI, only the emissions from vegetation and soils are included, but other relevant sources inclu de volcanic emissions, lightning, and sea salt spray

. Biogenic emissions from vegetation and soils are computed using models that utilize spatial information on vegetation and land use . The models also use environmental conditions of temperature and solar radiation to apply emission factors. The model inputs are typically horizontally allocated (gridded), and the outputs are gridded biogenic emissions , which can then be summed for use in planning inventories and speciated and utilized as input to photochemi cal grid models

. As described in Section 4.8.6 , a variety of models are available to estimate the emissions from vegetation and soils.

2.5.14 Inventory Codes Th e list provided below is a sample of the codes that can be used in building inventories; it is not a comprehensive list of codes that should be used in building inventories

. The EIS is the repository for the most updated valid codes used for building inventories

. Dozens of tables of codes are available to EIS

use rs from the “Reporting Code Tables” link on the EIS Gateway

. For others who do not have access to the EIS (e.g., contractors not working for a state, international users, and the general public), the EPA periodically posts Microsoft ® Access ® compilations of these codes at the Emissions Inventor y System Gateway under the “EIS Code T ables (including SCCs)” link.

Source classification c odes : An SCC means a pro cess
- level code that describes the equipment and/or operation [ or practice ] that is emitting pollutants (40 CFR 51.50 )

. 14 These codes are 8 digits for point sources and 10 digits for nonpoint and mobile sources

. The codes have multi

- level descriptions, whic h are included in the EIS codes table

. These codes are also used in the emission factors online database WebFire ( https://www.epa.gov/electronic

- reporting

- air

- emissions/webfire )

. The EPA also provides a web service with the most current list of codes, available at https://ofmpub.epa.gov/sccwebservices/

.

14 Several air agencies have raised the concern that SCC at industrial facilities is c onsidered CBI. However, this field is “emission data” required by the AERR and thus cannot be provided as CBI under CAA section 114(c).Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

29 North American Industry Classification System (NAICS) codes : The NAICS co des are U.S. Department of Commerce's codes for businesses by products or services and have replaced Standard Industrial Classification codes

. They are assigned to facilities in inventories to identify the primary industrial activity of the facility.

Feder al Informati on Processing Standards (FIPS) s tate and c ounty codes : Federal Information Processing Standards (FIPS) codes means the system of unique identifiers maintained by the National Institute of Standards and Technology, which are used to identify cou nties and county equivalents (e.g., parishes, boroughs) of the U.S. and its territories (e.g., American Samoa, Guam, Northern Mariana Islands, Puerto Rico, and US Virgin Islands )

. In the EIS Codes Tables, additional codes have been added to support offshor e regions and sources, such as asphalt plants, that do not remain in a single county during the entire year.

Tribal codes : A three

- digit code th at represents the American Indian Tribe or Alaskan Native entity

. The EIS Table also identifies which EPA region is associated with the tribe

. These codes are used instead of FIPS state and county codes when reporting emissions from tribal areas.

Pollutant codes : Pollutant code means a unique code for each reported pollutant assigned by the reporting format specifie d by the EPA for each inventory year (40 CFR 51.50)

. All of the crit eria pollutants , except for l ead , have codes that describe them: CO, NOX, VOC, SO2, NH3, PM10

- PRI, PM10

- FIL, PM25

- PRI, PM25

- FIL, and PM

- CON

. Lead and the hazardous air pollutants ( HAP s) us e numerical codes 15 to represent them, for example elemental l ead is 7439921 and elemental mercury is 7439976.

Control measure codes : Control measure means the name of the type of control device (e.g., wet scrubber, flar e, baghouse) or practice (e.g., produ ct substitution)

. The EIS Code Tables use a three

- digit numeric control measure code to represent each of the different types of controls, and identifies each as a device or a practice

. The control device type codes were updated with add itional codes in 20 13

. These codes are required when control devices are present because they are critical to understanding the nature of the emissions source and the possibility of additional emissions reductions to achieve attainment.

Emission calculation method : This fiel d is the code describing how the emissions for a pollutant were calculated ( e.g., by stack test, continuous emissions monitor, EPA emission factor, etc. ) (40 CFR 51.50). This is a required field for inventories because it allows the EPA to get some sense o f the quality of the emissions estimate

. Comment fields can also be used to further explain the origin of the emissions estimate.
Reporting period type : This field is the code describing the time period covered by the emissions reported ( i.e., annual, 5

- mo nth ozone season (previously used for NOx SIP call) , ozone season d ay, or average season day ) (40 CFR 51.50 ). In concert with the release of the final PM SIP Requirements Rule, a

15 These numerical codes are the unique numerical identifiers assigned and maintained by the Chemical Abstracts Service ( CAS) and are often referred to as CAS numbers or CAS registry numbers. The CAS numbers often appear with dashes embedded in the string of numbers, but these are dropped for most inventory reporting purposes.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

30 new code (“ASD”) has been updated in EIS to support submissions to EIS of ave rage season day emissions used for SIPs addressing the 24

- hour PM 2.5 standard. This field is also called the e mission type code in some references.

2.5.15 Point S ource F acility D etails See also Section 2.5.7 , which points to the sprea dsheets available that list all required and optional emissions inventory data elements.
Facility I nventory means the data tables of all facility information included in the EIS , but could also be used to refer to similar data tables for any inventory stor age system

. The facility inventory is the complete list of facilities, units, processes, and stacks associated with all point sources

. It is designed to be the latest repository of facility information and needs updating only when changes occur to faciliti es

. The facility inventory concept was intended to allow facility data to be constant except where real changes occur, allowing easier building and submitting of inventories and encouraging the use of consistent facility IDs, unit ID, process ID, and stack IDs from one inventory year to the next.
Physical address means the location address (street address or other physical location description), locality name, state, and a postal zip code of the facility. This is the physical location where the emissions oc cur , not the corporate headquarters or a mailing address (40 CFR 51.50 ).

Site name (also called Facility Site Name) means the name of the facility emitting emissions that are included in the inventory (40 CFR 51.50 )

.
EIS ID means any facility, unit, proce ss, or release point (stack) ID generated by the EIS and intended to remain constant for the life of that facility, unit, process, or stack across inventory years

. The proper names of the EIS IDs in the EIS system are EIS Facility Site Identifier, EIS Emis sion Unit Identifier, EIS Emission Process Identifier, and EIS Release Point Identifier.
Agency ID means any facility, unit, process, or release point (stack) ID generated by an agency reporting emissions to the EPA

. These IDs are used in the air agency da ta systems and may not match the EIS IDs described above

. The EPA tracks both the EIS IDs and a gency IDs within the EIS

. Using consistent agency IDs from year to year is highly encouraged , as it allows the EPA to more readily see which facilities are being reported for the AERR requirements

. Using inconsistent a gency IDs can result in duplicative facilities, units, processes, and release points within the EPA data systems.
Facility ID code (also called “Facility site identifier)” means the unique codes for a plant or facility treated as a point source, containing one or more pollutant

- emitting units (40 CFR 51.50 ) . The EPA's reporting format for a given inventory year may require several facility ID codes to ensure proper matching between databases ( e.g., th e state's own current and most recent facility ID codes, the EPA

assigned facility ID codes, and the ORIS (Department of Energy) ID code if applicable )

.
Unit ID code means a unique code for the unit that generat es emissions, typically a physical piece of

e quipment or a closely related set of such equipment (40 CFR 51.50 ). An example of a closely related set of equipment is a boiler and its control equipment . The EPA's reporting format for a given inventory yearEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

31 may require multiple unit ID codes to ensure p roper matching between databases ( e.g., the state's own current and most recent unit ID codes, the EPA

- assigned unit ID codes if any, and the ORIS (Department of Energy) ID code if applicable )

.
Process ID code is also called the “emission process identifie r” and it means a unique code for the process generating the emissions, typically a description of a process (40 CFR 51.50 )

.
Release Point ID code means a unique code for the point where emissions from one or more processes release into the atmosphere (40 CFR 51.50 )

. Traditionally called a Stack ID, but this was changed with EIS to acknowledge that many emissions releases do not come from stacks, such as fugitive emissions.
Release point type code means the code for physical configuration of the release poi nt (40 CFR 51.50 )

. The physical configurations include fugitive, vertical, horizontal, goose neck, vertical with rain cap, and downward

- facing vent

. The first two t ypes are the most common

. The release point type is particularly important for dispersion mo deling needed for permitting, risk modeling, and other purposes.

Release Point Diameter Measure (or Stack diameter ) means the inner physical diameter of a stack (40 CFR 51.50). This should be measured at the exit release point of the emissions , and the e xp ected reported units are feet

. Release Point Height Measure (or Stack height ) means physical height of a stack above the surrounding terrain (40 CFR 51.50)

. Expected reported units are feet

.
Release Point Exit Gas Flow Rate Measure (or Exit gas flow rate ) means the numeric value of the flow rate of a stack gas (40 CFR 51.50)

. Various unit s are permitted by the EIS

.
Release Point Exit G as T emperature Measure (or Exit gas temperature ) means the numeric value of the temperature of an exit gas stream in degrees Fahrenheit (40 CFR 51.50 )

. Release Point Exit Gas Velocity Measure (or Exit gas velocity ) means the numeric value of the velocity of an exit gas stream (40 CFR 51.50 ) . Various unit s are permitted by the EIS

. 2.5.16 Alternative IDs In addition to the primary fac ility, unit, process, and release point IDs, alternative IDs can be very useful for matching information in a given inventory to other databases

. In the case of the EIS, it stores not only the EIS unique IDs, but also the air agency IDs

. Other IDs are stor ed as well, including the following:
EIA Plant Code (a.k.a ORIS Plant Code )

. This plant ID is defined by the U

. S

. Department of Energy (DOE) Energy Information Administration (EIA) and used in its EIA

- 767 form

. It has previously been defined as the Office of Regulatory Information System (ORIS) code, though that term is no long used by DOE

. The EPA ’s Office of Atmospheric Programs ’ (OAP) Clean Air Markets Division (CAMD) uses whatever code was originally assigned to the facility as the tracking code for com piling data for its emissions markets in support of the acid rain program and NO X trading, in particular the CEMS data.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

32 CAMD Unit ID

. In addition to the EIA facility IDs, CAMD uses unit IDs for storing the emi ssions markets data as well

. The EIS stores the unit codes used by CAMD as an alternative ID called “EPACAMD , ” and the values are usually based on the CAMD hourly CEMS data reports

. These have historically also been referred to as ORIS Boiler or ORIS Unit IDs, however, th ose reference s are no longer valid.
IPM/NEEDS ID

. The EPA Integrated Planning Model (IPM) is used to forecast future

- year electricity demand and emissions. Underlying thi s model is t he National Electric Energy Data System (NE EDS ) database that contains the generation unit records used to construct the “model” plants that represent existing and planned/committed units in EPA modeling applications of IPM

. This database mostl y uses IDs that are often the same as the EIA Plant Codes and the CAMD Unit IDs, but this database has more units than are included in the hourly CEMS data

. In the EIS , the EPA stores these alternative IDs as “EPAIPM” IDs.
Toxics Release Inventory ( TRI ) ID is used by the EPA ’s Office of Environment al Information to build the T oxic s Release I nventory from facility

- submitted facility

- total emissions to air, water, and land

. This database includes NH 3 , which is why it can be relevant to the NAAQS for PM 2.5 implementation

. In the EIS , the EPA stores these alter n ative IDs as “EPATRI” IDs.
Federal Registry Service (FRS) ID is used by the EPA ’s Office of Environmental Information to link many EPA databases with facility information (see https://www.epa.gov/enviro/facility

- registry

- service

- frs ).

2.5.17 Location D efinitions Geographic locations are critical in point source invento ries for identifying the location of the emissions. In the EIS , locations can be provided for both the facility center and for individual release points

. Fugitive release points have additional parameters that can be specified , such as the orientation of t he release, and these parameters are listed in the spreadsheets available that list all required and optional emissions inventory data elements, referenced in Section 2.5.7

.
Latitude Measure (or just latitude) is the measure of the angular distance on a meridian north or south of the equator. Reported as decimal degrees.
Longitude Measure (or just longitude) is the measure of the angular distance on a meridian east or west of the prime meridian. Reported as decimal degrees.

Hori zontal Accuracy Measure is the measure of accuracy (in meters) of the latitude/longitude coordinates.
In addition, refer to https://www.epa.gov/geospatial/latitudelongitude

- data

- standard for more information on the proper usage of the following code set.

Horizontal Collection Method Code is the m ethod used to determine the latitude/longitude coordinates for a point on the earth. For example, 001 is address matching

- house number, and 004 is address matching nearest intersection.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

33 Horizontal Reference Datum Code represents the reference datum used to determine the latitude/longitude coordinates. Options are: 001 (North American Datum of 1927), 002 (North American Datum of 1983) , and 003 (World Geodetic System of 1984).
Geographic Reference Point Code represents the place for which geographic coordinates were established. Code value should be 106 (e.g., point where substance is released).

2.5.18 Control Data E lements Control efficiency mean s the efficiency by which a control device or measure reduces emissions for a particular pollutant

. For emissions reporting in accordance with the AERR, this data element applies for both point and nonpoint sources and is called the “ Percent Control Measur es Reduction Efficiency

. ” For point sources, the data element is included in the “ Control Pollutant Table ” of the facility staging table s

. For nonpoint sources, the data element is included in the “ Control Pollutant Table ” of the nonpoint staging table s . I n the EIS , it is a percent and should be reported as a value greater than or equal to 0.1 and less than or equal to 99.9 ( the EIS allows for one decimal place only).

Control C apture efficiency means the percentage of an exhaust gas stream actually collecte d for routing to a set of control devices (40 CFR 51.50). It is sometimes combined within the v alue for the control efficiency, but unlike control efficiency , it is not pollutant

- specific

. For emissions reporting in accordance with the AERR, this data elem ent is for point sources only, and it is called “ Percent Contro l Capture Efficiency ” and is included in the “ Control Approach Table ” of the facility staging table s

. It is a percent and should be reported as a value greater than or equal to 0.1 and less tha n or equal to 99.9 ( the EIS allows for one decimal place only).

Control Effectiveness means the percentage of time or activity throughput that a control approach is operating as designed, including the capture and reduction devices. This percentage account s for the fact that controls typically are not 100 percent effective because of equipment downtime, upsets and decreases in control efficiencies (40 CFR 51.50).

Control effectiveness i s a n estimate of the portion of the reporting period's activity for whi ch the overall control system or measure (including both capture and control measures) were operating as designed (regardless of whether the control measure is due to rule or voluntary). It applies to both point and nonpoint sources and is not pollutant

- sp ecific

. For point source emissions reporting in accordance with the AERR, this data element is called “ Percent Control Approach Effectiveness ” and is included in the

“ Control Approach Table ” of the facility staging table s . For nonpoint source emissions rep orting in accordance with the AERR, this data element is also called “ Percent Control Approach Effectiveness ” and is included in the “ Control Approach Table ” of the nonpoint staging tables

. In the EIS , it is a percent and should be reported as a value grea ter than or equal to 0.1 and less than or equal to 99.9 ( the EIS allows for one decimal place only)

. For nonpoint, see also “rule effectiveness , ” below.
Rule penetration means the percentage of a nonpoint source category activity that is covered by the rep orted control measures (40 CFR 51.50). For emissions reporting in accordance with the AERR, this data element is called “ Percent Control Approach Penetration ” and is included in the “ Control ApproachEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

34 Table ” of the nonpoint staging tables

. In the EIS , it is a percent and should be reported as a value greater than or equal to 0.1 and less than or equal to 99.9 ( the EIS allows for one decimal place only).

Rule effectiveness means a rating of how well a regulatory program achieves all possible emissions reducti ons

. It is analogous to the “control effectiveness” above and , for emissions reporting in accordance with the AERR, this information is reported using the EIS Control Effectiveness field for nonpoint (see above). Like control effectiveness, it should refle ct the assumption that controls typically are not 100 percent effective because of equipment downtime, upsets, decreases in control efficiencies, noncompliance, and other deficiencies in emission control . Rule effectiveness adjusts the control efficiency f rom what could be realized under ideal conditions to what is actually emitted in practice due to less than ideal conditions

. 2.5.19 EIS Sectors , Tiers , and Facility Type Because emissions inventories are large and detailed, most reports about emissions inventori es include summaries of the contents of those emissions

. Some summaries use the data categories described above (point, nonpoint, on

- road, nonroad, events, and biogenic)

. For other summaries, that level of detail is not enough. The EIS SCC tables provide t hree other mechanisms for summar ies, all of which depend on SCC.
First, the SCCs have a four

- part description, and the first three levels of this description could be used as a summary category

. Second, the SCCs are assigned to “Tiers” using the fields “Ti er 1 Description , ” “Tier 2 Descripti on , ” and “Tier 3 Description

. ” These Tiers have been used traditionally as part of many EPA reports and trends for criteria emissions

. While wildfires are included in the “Miscellaneous” Tier 1, wildfires are sometimes s eparately broken out from Miscellaneous because of their natural origin and because they can be a large contributor for some pollutants. Finally, the EIS Sectors can be used to summarize emissions (this is the field “Sector” in the EIS SCC code table). The EIS Sector was added with the creation of the EIS and allocates emissions to about 60 categories with multi

- pollutant inventories in mind

. Whereas the Tiers are more useful for criteria pollutants, the EIS S ectors work better for the combination of HAPs a nd CAPs

. The EIS Sectors can also be further aggregated to provide custom summaries; one example of this is presented in the report “2008 National Emissions Inventory: Review, Analysis and Highlights” (EPA

- 454/R

- 13

- 005, May 2013).

2.5.20 Other Terms High electric ity demand day (HEDD) means a n ozone season day when demand for electricity is high. A study of the Northeast Corridor 16 air quality has indicated that NO X emissions from EGUs during HEDD periods may be significantly greater than emissions that occur on an average ozone season day.
Distributed generation means the use of small power generators sited at or near the point of energy consumption. This usually occurs during periods of peak energy demand or emergency loss of the normal EGU generating capacity . Dis tributed generation sources of electricity can include rooftop solar

16 “High Electric Demand Day and Air Quality in t he Northeast.” White Paper Prepared by the Northeast States for Coordinated Air Use Manageme nt. June 5, 2006. Available at: http://www.nescaum.org/documents/high

electric

- demand

- day

- and

- air

- quality

- in

- the

- northeast/final

- white

- paper
- hi

- e lectric

- demand

- day

- 06052006.pdf

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

35 or wind sources , biomass combustion, as well as backup fossil fueled generators or other engines. T he combustion sources of distributed generation can cause emissions that could be of int erest for SIP planning purposes.
RFP projected emissions means the estimated emissions for direct PM 2.5 and PM 2.5 plan precursors by sector for the years in which quantitative milestones are due for a nonattainment area.



## 3 SIP Inventory Requirements and Reco mmendations As described in Section 2 , there are many required and potentially required inventory efforts needed as part of a SIP development effor t

. This section covers the fundamental attributes of planning inventories and th eir preparation

. The topics covered include the timing of the various inventory components (Section 3.1 ) , the inventory preparation plan (Section 3.2 ) , the base year inventor ies (Section 3.3 ) , the ROP/ RFP baseline NAA inventory (Section 3.4 ) , the ozone periodic inventory (Section 3.5 ) , the ozone emissions statement requirement for SIPs (Section 3.6 ) , maintenance invent ories (Section 3.7 ) , the projected inventor ies (Section 3.8 ) , public hearings (Section 3.9 ) , and submitting the inventory to the EPA for approval (Section 3.10 )

. The details of inventory preparation for base year inventories and projected inventories are left for Sections 4 and 5 , respectively.



### 3.1 Inventory Component Timing Table 8 provides the timing requirements and recommendations (for optional items) for the inventory components of SIPs

. Where this table is inconsistent with the ozone, PM 2.5 , or regional haze regulatory
text tha t is applicable at the time a SIP is prepared and reviewed , the regulations have precedence over the information provided here.

Table 8 : Timing of emissions inventory components Inventory Component Required: Timing Inventory Prepa ration Plan Prior to preparation of emissions inventories covered by the SIP

.
Base year NAA inventory Ozone Within 2 years of the effective date of designations

PM 2.5 Within 18 months from the date of a nonattainment

designation.

ROP/ RFP baseline NAA inventory Ozone Moderate & above: Within 3 years of the effective date of designations. Serious & above: Additional plan within 4 years.

PM 2.5 Within 18 months from the date of a nonattainment

designation. Periodic NAA inventory Ozone The end of each 3

- year period after SIP submittal until the NAA is redesignated to attainment. Source Emission Statements requirement for SIPs Ozone Within 2 years of the effective date of designations

. Base case statewide inventory Ozone and PM 2.5 + With modeled attainme nt demonstration (if required,

for convenience, can be included with the inventory SIP)

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

36 Inventory Component Required: Timing

Attainment p rojected inventory for the NAA Ozone:
s ummary only For Ozone, With SIP and/or ROP/RFP plan. On

- road

portion can become the motor vehicle emissions budget.

PM 2.5 Within 18 months from the date of a nonattainment

designation. Projected statewide inventory (summaries) Ozone and PM 2.5 + With modeled attainment demonstration (for

convenience, can be included with the inventory SIP)

. Baseline statewide invento ry (summaries) Haze Previously completed for initial Regional Haze SIPs

. Subsequent progress reports and SIP revisions may refer to this inventory.

Recent statewide inventory (summaries) Haze Needed for the progress reports that are due e very 5 years (or periodically) from submittal of initial Regional Haze SIP. ∆ Also needed to support Regional Haze SIPs for second and subsequent implementation periods, due every 10 years beginning on July 31, 2018 α Projected statewide inventory for 2018 (summaries) Haz e Previously completed to support first Regional Haze SIP (due by December 17, 2007) Projected statewide inventory for 2028, 2038, etc. (summaries) Haze To support Regional Haze SIP s for second and subsequent implementation periods, due every 10 years beg inning on July 31, 2018 α

. Public hearing Ozone and PM 2.5 Prior to submittal of inventory for approval by the EPA. Inventory documentation All With associated SIP. Maintenance NAA inventory Ozone and PM 2.5 After attainment, with a redesignation SIP.

+ Only required in associ ation with modeled attainment demonstration

. If the inventory needed for the modeled attainment demonstration is not the entire state, then a “statewide” inventory would not need to be provided, but rather the emissions from the part of the state included in the modeling domain could be provided instead. ∆ On May 4, 2016, the EPA proposed to revise the timing of and requirements for the 5

- year progress report requirement so that it is not considered a SIP revision, while the 10

- year requirement would remain a SIP revision (see https://www.epa.gov/visibility/proposed

- rulemaking

- amendments

- regulatory

- requirements

- state

- regional

- haze

- plans )

. α In the same proposed revision noted in th e previous footnote, the EPA proposed to revise the requirements for submitting SIPs that include an extension of the due date to July 31, 2021

. Subsequent interim progress report submission deadlines have been proposed to be adjusted so that second and su bsequent progress reports would be due by January 31, 20 25 , July 31, 2033, and every 10 years thereafter

. 

### 3.2 Inventory Preparation Plan
A ir agencies can use IPPs as a planning tool to guide inventory preparation and to help ensure that emission estimates are of a high quality and consistent with CAA requirements

. In accordance with 40 CFR 51.5(b), states are urged to use applicable, state

- of

- the art techniques for estimating emissions. In
some cases, the EPA Regional office s will have a preset list of expectat ions for air agencies to include in their SIP and will provide this information to the agency at the start of the SIP planning process

. In these cases, an IPP may not be needed, especially for air agencies with prior SIP development experience for a partic ular NAAQS.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

37 The IPPs are an opportunity for state and local agencies to tell their EPA Regional office how the y plan to compile their emissions inventories and allow the EPA to provide feedback prior to the agency spending resources in preparing their inve ntory

. They can also allow the EPA Regional office s to coordinate to maintain consistency across attainment plans where that is advisable

. The IPPs can be especially valuable for agencies with new nonattainment pr oblems, less experienced inventory staff or for agencies otherwise needing additional feedback on inventory development

. If used, IPPs precede the development of inventories; therefore, the timing of IPPs is e arly in the SIP planning process

. The EPA recommends that air planning agencies coordinate with their Regional office on the need for a plan, the timing of delivery of the plan, the response time back from the EPA on the plan , and any other IPP approval process details

. Agencies should recognize that time may also be needed in their planning sc hedule to addres s the EPA comments on the plan, while the EPA Regional office s will attempt to provide as timely feedback as possible

. A high

- quality IPP could be a strong foundation for the emissions inventories used in planning and/or attainment modelin g, which are themselves critical pieces of SIP development ; therefore, t he IPP should include enough details for the EPA to properly assess what the agency plans to do

. The content can include a number of key elements, for which a checklist is provided in Table 9

. The actual elements to include in a specific IPP can depend on a number of factors, depending on the needs of the state or local agency as well as the EPA for understanding the inventory plans

.
Table 9 : Checklist of elements to c onsider for i ncluding in Inventory Preparation Plan s

IPP Element Important for
a High Quality IPP ? Inventory objectives

– the purpose and scope of the inventory Y The inventory year(s) and rational e for selecting them Y The pollutants to be included, including the expected definition of VOC (for inventories needing VOC) Y
For PM 2.5 , the temporal basis expected to be used for the SIP emissions, which can include annual, average season day, or both (see Section 4.5 ) Y A list of inventories to be included with the SIP, including the types (e.g., reports , data summaries) and formats of information (i.e., electronic data files and their expected formats, electronic media used for transfer ) , that t he agency intends to include in their SIP Y

Plans for (or results of) identifying the most important source sectors to the nonattainment problem Y The source categories to be included, the emissions level(s) for defining point sources, and if available, the expected priority for these Y The plans for compiling the inventory, including any other known inventories and how the agency plans to assess and improve upon what is already available A summary of expected approach differences among different inven tories that could be the same (e.g., between a base year NAA inventory and a base year modeling inventory)Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

38 IPP Element Important for
a High Quality IPP ? For projected inventories: The drivers for future

- year emissions growth and reductions Y + The source categories to be forecast Y + The ex pected approaches for forecasting each source category Y + A plan for public review Important sources of emissions or other inventory uncertainties Quality assurance steps to be taken Y A schedule for inventory preparation, review, and submission t o the EPA , including any plans to submit pieces of the inventory separately and in accordance with regulatory timeline requirements Y

+ If a projected inventory is required

. In addition to Table 9 , other inventory planning resour ces may be of use for agency planning purpose s

. During the preparation of their IPPs, state and local agencies are referred to Volume I of the EIIP
g uidance , available at http://www.epa.g ov/ttn/chief/eiip/techreport/volume01 , which discusses emissions inventory planning and development

. While somewhat out of date, the EIIP volumes still can help guide new inventory developers , especially with basic information about creating emissions

. Us ers of that document should defer to this guidance where newer information is provided, such as updated versions of mobile models

. For stationary point sources, a good resource is EIIP Volume II, Chapter 1, Section 3

. For nonpoint sources, EIIP Volume III, Chapter 1, Section 2 gives nonpoint

- specific planning information

. The mobi le source volumes for EIIP are more out of date and the EPA Office of Transportation and Air Quality ( OTAQ ) mobile source guidance is preferable (see Table 1)

. A quality assurance plan should always be a part of the IPP

. In cases where a more formal QAPP is developed, the QAPP will satisfy the need for an IPP quality assurance plan

. In some cases, the EPA Regional office s will include a QAPP or other quality assurance requirement a s part of their CAA s ection 105 grant to a state that typically includes funding for emissions inventory development. Each Regional office manages its own quality assurance plan. Information about EPA quality assurance specifications and tools as well as a map that links to each Regional office ’s quality assurance project are available at https://www.epa.gov/quality

.
For additional information on quality assurance planning , Chapter 2 of Volume VI, “ Quality Assura nce Procedures and DARS software ” ( https://www.epa.gov/air

- emissions

- inventories/volume

- 6

- quality

assurance
- procedures

- and

- dars

- software ) provides some general guidance for quality assurance and some specific approaches to uncertainty evaluation

. Other quality assurance resources include Section 0 of this guidance , and quality assurance steps described in the lat est NEI Technical Support Documentation available at the latest NEI documentation page link on the main NEI web page

. Where air agencies are relying on their NEI sub mission as a starting point for meeting any SIP inventory requirements, a QAPP developed for that air agency’s NEI submission may offer a starting point for the SIP inventory QAPP.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

39 

### 3.3 Base Year Inventory The purpose of the base year inventory is to provide a current and comprehensive data source for emissions contributing to the air quality problem addressed by the SIP

. In the case of ozone and PM 2.5 , the inventory requirement is for the NAA , whereas for regional haze, the inventory requirement is for a
statew ide inventory

. As listed in Table 4 and Table 5 , the ozone or PM 2.5 SIPs can include statewide inventories as part of the modeled attainment demonstration, and these can be included as separate inventory submissions included with the NAA inventory.

The general SIP provisions in CAA section 172(c)(3) explains that base year inventories should include a

“ comprehensive, accurate, current inventory of actual emissions from all sources” in the applicable area

. Details associated with preparing a base year inventory are provided in Section 4 , including selection of year(s), temporal extent, spatial extent, pollutants to include, approaches for developing emissions, data codes, and qua lity assurance

. Additionally, CAA section 182(a)(1) provides a specific base year inventory requirement for ozone SIPs. PM 2.5 SIPs generally rely on the general SIP provisions in CAA 172(c)(3), though some PM

- specific elements of CAA section 189 impact the timing and other aspects of PM 2.5 SIP inventories. Other requirements for SIP inventories are found in the SIP implementation rules as listed in Table 4.
The base year inventory is the starting point from which the other SIP

- related inventories are derive d

. These other inventories should relate to the base year inventory with regard to the emissions sources included, pollutants, temporal aspect, and other key aspects that allow the SIP to be a coherent and connected plan across the various inventories. For planning purposes, the base year inventory provides a way for decision makers to consider the sources of emissions that contribute relevant pollutants and consider emissions reductions strategies needed for the SIP.

Section 4.1 covers the choice of inventory years for the base year inventory

. The choice of the inventory year for the planning is a critical one that significantly impacts the workload of inventory staff and greatly depends on availability of data and timing of oth er inventory efforts required by the EPA

.
Section 4.2 covers the pollutants to be included in the base year inventory . These pollutants differ depending on the nature of the air quality problem for a given SIP

. Where feasible, the EPA encourages planning agencies to include precursors for all ongoing nonattainment problems in a state to promote efficiency in preparing multiple base year inventories, and to allow for the consideration of emissions reduction strategies that improv e air quality across multiple air quality concerns and nonattainment issues

. In addition, states may wish to include emissions of HAPs , which can have co

- benefit reductions associated with strategies aim ed at reducing ozone, PM 2.5 , and/or regional haze.

T h e spat ial and temporal extent of the base year inventories are also an important inventory characteristic

. These topics are covered fully in Sections 4.4 and 4.5

. Each of the implementation rules fo r ozone, PM 2.5 , or regional haze has different considerations and requirements associated with the planning inventories

. For example, ozone NAA inventories must include ozone season day emissi ons, the PM 2.5 NAA inventories can be either annual or season da y (depending on the nature of the PM 2.5 nonattainment problem), and the regional haze inventories are only annual.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

40 The Ozone Implementation Rule and PM 2.5 SIP Requirements Rule require inventories for the NAA

. These inventories are called the base year inv entory for the NAA. These inventories may need to be updated through multiple iterations of a SIP when they are used a baseline inventories for assessing progress for ROP/RFP. For regional haze, the inventory is commonly called the baseline inventory. For clarity here, we also call the regional haze inventory the baseline statewide inventory to distinguish it from a NAA inventory.



### 3.4 Rate of Progress and Reasonable Furth er Progress Baseline NAA Inventor y RFP is a concept included in the CAA under Part D, T itl e I to assure that states take steps to ensure that the air quality in NAAs makes steady and incremental progress toward attaining air quality standards

. The ROP/RFP baseline NAA inventory is necessary for ozone NAAs designated as Moderate and above

. This baseline inventory is part of a plan or plans that meet the RFP requirements as described by the CAA and the Ozone Implementation Rule , and summarized here. The PM 2.5 SIP Requirements Rule also includes requirements for RFP as described below. Though there are specific considerations related to ROP and RFP, the anthropogenic portion of the base year inventory for the NAA also serves as the base ROP/RFP baseline NAA inventory for both ozone and PM 2.5 SIP development.

3.4.1 Ozone ROP/RFP Requirements and Timing CAA section 182(b)(1)(A) requires Moderate and above NAAs to submit a plan to ensure a 15 percent VOC reduction (accounting for growth) by 6 years after the NAA designation , which is the Moderate area maximum attainment date

. Th e 15 percent reduction requirem ent is commonly called “ rate of progress ” or ROP. According to the Ozone Implementation Rule , air agencies must submit this plan within 3 years after the area’s nonattainment designation. This timing aligns with the Moderate NAA deadline for submittin g att ainment demonstration SIPs

. In addition, CAA section 182(c)(2)(B) requires each Serious and above ozone NAA to submit a plan to achieve a t least a further annual 3 percent VOC reduction

. Additionally, CAA s ection 182(c)(2)(C) allows for substitution of NO X for VOC emissions reductions in the plan under certain conditions

. This requirement is also called “annual RFP

. ” As described by the Ozone Implementation Rule , the annual RFP requirement applies for any remaining 3

- year periods out to the attainment date beyond the first 6 years. According to the Ozone Implementation Rule , air agencies with NAAs classified as Serious and higher must submit this plan within 4 years after the area’s nonattainment designation. This timing aligns with the Serious and higher ar eas’ deadline for submitting attainment demonstration SIPs; however, these NAAs still must submit the plan for ROP within 3 years.

State s maintain the flexibility to submit plans early to provide more time for implementation of their SIP control measures

. The EPA recommend s that state s complete their ROP/RFP plan s as expeditiously as practicable after designation to provide as much time as possible for sources to implement the emission reductions.
The associated terminology for the various plans and invento ries can be confusing, and so the terminology used in this guidance is described here. In this guidance, we use “ ROP/ R FP plan” to referEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

41 generally to all plans ( i.e., those addressing just the 15 percent ROP requirement for Moderate areas as well as plans a dditionally addressing the annual RFP requirement )

. For Serious and above areas, s ince the timing allows that two separate plans for ROP and annual RFP could be submitted (i.e., at 3 years and 4 years after designations, respectively), it may also be neces sary to refer to such plans separately

. Consequently, this guidance uses “ROP/RFP plan(s)” to allow for the idea that multiple plans could be submitted. Lastly, in the case where the individual plans must be referenced, they will be called “ROP plan” and “ RFP plan

. ”

3.4.2 Ozone ROP/RFP Emissions Guidance The same ROP/RFP baseline NAA inventory is used for all ROP/ RFP plan ( s ) , regardless of whether they address the ROP requirement (for Moderate areas) or both ROP and annual RFP (for Serious and above)

. As implied by the name, these inventories include emissions data just for the NAA region and not other areas in a state. The purpose of the ROP/RFP baseline NAA inventory is to provide a reference point to determine the emissions reductions that must be achieve d for the 15 percent VOC (or NO X ) reduction and the subsequent 3 percent reductions for Serious areas and above out to the attainment date. This requirement stems from CAA requirements.
For ozone, VOC and NO X should be included in the ROP/RFP baseline NAA invent ory. Further, the EPA expects that the year of the ROP/RFP baseline NAA inventory will be the same year used for the base year inventory for the NAA.

For o zone, t he ROP/RFP baseline NAA inventory emissions should be provided using the same base year as is used for base year inventory for the nonattainment area. In most cases, the ROP/RFP baseline inventory should also have the same emissions values as are in the base year inventory for the NAA

. One key exception is that biogenic emissions should not be incl uded in the ROP/RFP baseline.
The EPA also expects that the spatial extent of the ROP/RFP baseline NAA inventory will also match the base year NAA inventory so that they are both either “whole county” inventories or both consistently “partial county” inve ntories. Section 4.4.1 provide s more information on partial county inventories.

In the event that updated ROP/ RFP p lan (s) are needed after initial submittal to meet the requirements of the Ozone Implementation Rule , the ROP/RFP baseline NAA inventory may also need to be updated. This can occur with significant methods changes, such as updated mobile models

. For example, after an initial ROP/ RFP p lan has been submitted as part of a SIP, a new mobile model may become available tha t alters the emissions estimates. It would be inconsistent to compare estimates from a new mobile model at the end of a 6

- year period to estimates using an o ld model at the beginning of that 6

- year period , and so the EPA c ould be unable to determine whethe r a 15 percent reduction (or subsequent 3 percent reductions) can be (or has been) achieved by an ROP/ RFP plan. Thus, an updated ROP/RFP baseline NAA inventory may need to be created using the updated mobile model to appropriately meet the requirements of the Ozone Implementation Rule

.
Additional ROP/RFP emissions reductions guidance is provided in Section 3.8.2

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

42 3.4.3 PM 2.5 RFP Requirements and Timing Section 172 of the CAA addresses the PM 2.5 attainment plan provisions in general

. I n addition, Section 189(c) of the CAA requires that PM 2.5 SIPs contain quantitative milestones, which are to be achieved every 3 years until the area is redesignated attainment and which demonstrat e reasonable further
progress

. For Moderate areas, these qu antitative milestone years would be no later than 4.5 and 7.5 years after designation of the area. For Serious areas, these quantitative milestone years are no later than 7.5 and 10.5 years after designation of the area. Most (if not all) Serious areas wil l have first been Moderate areas, and thus could also be subject to the quantitative milestone at 4.5 years as well

.
In the PM 2.5 SIP Requirements Rule , one required element of an RFP plan is RFP projected emissions by sector and precursor pollutant for ea ch applicable quantitative milestone year

. In addition, the emissions reductions must show that the implementation schedule (of reductions) achieves either (1) generally linear progress toward the projected attainment date; or (2) stepwise progress toward the projected attainment date. The rule also holds out the possibility that a state could develop an approvable RFP plan even if emissions of one or more PM 2.5 plan precursors were not decreasing; however, additional analysis would need to be done (as desc ribed in the rule).

3.4.4 PM 2.5 RFP Emissions Guidance For PM 2.5 SIPs , all plan precursors must be included in the RFP emissions provided as part of the RFP plan . Further, the EPA e xpects that the year of the RFP baseline emissions will be the same year used for the base year inventory for the NAA.
Unlike other emissions inventory requirements , the PM 2.5 RFP requirement does not specify that detailed projected emissions inventory data must be developed and submitted to the EPA. The emissions requirement for most sectors is for “ RFP projected emissions for direct PM 2.5 and all PM 2.5 plan precursors for each applicable milestone year , ” which does not indicate a detailed emissions inventory

. 17 In addition, the PM 2.5 SIP Requirements Rule preamble specifically indicate s emissions provided by sector and pollutant are expected. It would be sufficient to include a table that has rows for each sector and columns for the baseline and projected emissions of all relevant pollutants.

S tates may be able to develop their RFP pro jected emissions in some cases with less effort than it would take to do a detailed emissions inventory projection

. One approach for the calculating sector/pollutant emissions for the milestone years would be to rely on the projected attainment inventory f or the NAA and use linear interpolation from the baseline year to the milestone year(s). To take this approach, states should explain why the linear assumption makes sense for a particular sector. For example, residential work combustion emissions are proj ected to the future in part through phase

- in rate assumptions for newer and lower emitting woodstoves. Using this sort of “% adoption per year ” approach would support using a linear rate of change assumption such that the whole residential wood combustion sector could be interpolated between the baseline year and the projected attainment year.

17 For the purposes of motor vehicle emissions budgets for transportation conformity (as required by 40 CFR part 93), an inventory of onroad mobile source emissions in the NAA is required ( see 40 CFR 51.1012(a)(2)).Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

43 

### 3.5 Periodic Inventor ies
T he Ozone Implementation Rule require s a periodic inventor y for the NAA, and the Regional Haze Rule requires a “ recent year” statewide inventory

. The ozone periodic inventories should be consistent with the base year inventory in the temporal extent (seasonal, annual, or both), spatial extent (statewide, NAA counties, partial coun ties), and sources inventoried. In some cases for ozone , it may also be advisable to have the emissions inventory methods of the periodic inventory consistent with the base year inventory , but this decision should be made in consultation with the relevant EPA Regional office

. Regional office s may consider additional relaxat ion of the consistency recommendation above in specific instances. For regional haze, the “recent year” inventory must always be statewide. T here is no expectation that the recent year inventories for regional haze will use consistent methodologies as wer e used for the baseline inventory for a year in the range of 2002

- 2004 submitted as part of the first Regional Haze SIP revision

. Rather, the most recent emission estimation methods would be expected to be used.

3.5.1 Ozone Periodic Inventory For ozone , the req uirement in 182(a)(3)(A) is that the periodic inventory be submitted no later than each 3

- year period after the submission of the base year NAA inventory

. This language provides the flexibility to air agencies to submit sooner than 3 years, but not later t han 3 years

. If any other current NAA inventory is being submitted to the EPA for any reason, including ROP/ RFP plans, then states should consider also using that data to meet the periodic inventory requirement. Also, i f the air agency comes into attainmen t and receives a Clean Data Determination prior to the 3

- year period, or if a maintenance plan (with a maintenance inventory) is being submitted prior to or in sync with this 3

- year timetable, then the these actions are very likely to make it unnecessary f or the air agency to submit a separate ozone periodic inventory

. Since the periodic inventory requirement in the CAA does not specify the degree of detail required for the periodic inventory, the EPA has defined the necessary components through the AERR

. T hus, whether the inventory is submitted as a separate submission or through the AERR, it would need to be consistent with requirements of the AERR in order to meet the statutory period ic inventory requirements

. The periodic inventory is a check

- in with the air agency on how the emissions are trending , and ha d previously been considered to not have “regulatory significance” or been treated as a SIP submission. This is no longer EPA’s recommended approach. In accordance with the CAA, p eriodic inventories are a revision to the inventory portion of the ozone SIP and are thus subject to C AA section 110 and 40 CFR 51.102 , 103 , and Appendix V. For discussion of public hearings, please see Section 3.9 of this guidance document

.
To meet t he periodic inventory requirement for ozone, the periodic inventories must include ozone
season day emissions values

. Since this emissions type is allowed to be submitted to the EPA through EIS for the AERR, it is possible that the AERR submission could me et the periodic inventory requirement if the conditions listed in Table 10 apply

. A s with all SIP requirements, air agencies should coordinate with the Regional office regarding what is appropriate for a particular NAA.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

44 Table 10 : Conditions for AERR submittal to meet o zone p eriodic i nventory r equirement
Condition Comment

Public hearing requirement A public hearing has been offered and either no party requested a public hearing or a public h earing has been held. Evidence should be provided that this requirement has been met. Ozone season day emissions must be submitted for the NAA counties If ozone season day emissions cannot be extracted from the EIS (as is the case in 2014), using an AERR submission to meet the periodic inventory requirement is only acceptable if approved by the Regional office

.

Emissions are submitted for mobile sources. Ongoing review of the AERR may result in requiring mobile model inputs and making emissions data optio nal

. If this occurs, the SIP periodic inventory must still include emissions

. Thus, emissions would need to be submitted for the NAA counties regardless of any AERR requirements to be able to meet the periodic ozone inventory requirement.

Complete

– all s ectors Using the AERR to meet the periodic inventory requirement is only possible during triennial years (see Section 2.4 ) because the EIS only accepts nonpoint and mobile data during these years, and these data categories must be included to be complete. Submitted within 3 years since the base year inventory. It is acceptable to be less than 3 years, after which time the triennial submissions would be every three years.
Partial county approach approved by Regional office The EIS do es not su pport partial counties

. In some cases, it may be acceptable to use the entire county emissions for the periodic submission.
Notification If the AERR approach is approved, the Regional office should be notified in writing when the submission has been completed.

Documentation Must be created

. Submission is at the request of the EPA Regional office

. The degree of documentation for periodic inventories can be less than that of other inventories because of the lack of regulatory significance.

3.5.2 Regional Haze Recent Year Inventory For the R egional H aze R ule, a recent year inventory is needed to support the analyses required with each 5

- year (or “periodic,” as proposed) progress report or 10

- year SIP revision

. The inventory is not submitted with t he SIP or progress report , but emissions summaries are expected as part of the analysis provided with the SIP. The inventory to be used is a complete statewide annual inventory as was the initial baseline inventory ( included in the original Regional Haze S IP)

. See Table 1 above for the latest reference materials with guidance on the Regional Haze Progress Reports

. Since the r egional h aze requirement is for inventories to be statewide and cover emissions over an annual period , the spatial and temporal aspect s better match the AERR reporting requirements as compared to the NAA inventories required for ozone and PM 2.5 implementation . In addition, since the recent year inventory is not an element of the SIP that must be submitted itself, there is not a public he aring requirement for the inventories used for regional haze. Thus, the AERR inventories are an appropriate starting point forEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

45 meet ing the requirement for the recent year inventory for regional haze

. If better information becomes available for particular s ource sectors at a time when it can be incorporated into a state’s long

- term strategy development, it should be.
The inventory approach for the recent year inventories needed for 5

- year (or “periodic,” as proposed) progress reports and 10

- year SIP revision s is relatively straightforward. The following list provides considerations for states in developing their inventor ies :

 The rule prescribes that the inventory year is the same as triennial AERR year that has most recently been submitted by the state to th e EPA , with additional special considerations

o For the recent year emissions inventory for a 10

- year SIP revision, states can use another inventory year if adequately justified ( see 40 CFR 51.308(f)(2)(iv)) . One example of using another year would be to upd ate the EGU portion of the inventory to use more current data that is available because of CEMs. There may also be better information on a particular source sector in a special study that collected more refined source

- specific information but for a differe nt year.

o For the 5

- year (or “periodic,” as proposed) progress reports, 40 CFR 51.308(g)(4) specifically requires that any newer data reported directly to the EPA (like the CEM data) be used if summaries of the data are available from the EPA.

 The inventor y can be the same as the NEI or can be revised from the NEI. The proposed revision to the rule does not say that the inventory must be the NEI inventory, rather, it says that the year must be the same year.

 States must identify the recent inventory in thei r plan, but the inventory does not need to be submitted to the EPA.

 States may rely on EPA

- provided parts of the NEI to support the recent year inventory data needed for their plan.



### 3.6 Emissions Statement Requirement for SIPs
For ozone NAAs, states should dev elop emission reporting programs for VOC and NO X sources in accordance with CAA section 182(a)(3)(B). T h e required state program and associated regulation defines how states obtain emissions data directly from facilities and report it to the EPA as part of SIP inventories and for the AERR

. This is called an Emission Statement regulation, and it outlines how facilities must report emissions and facility activity data to an air agency . Once the air agency develops the Emission Statement regulation, the regula tion should be sent to the EPA as a SIP for approval by the deadline as specified in Table 8. As an element of a SIP, the public hearing requirements apply to the Emission Statement SIP. Air agencies must ensure that their emissions reporting program, prom ulgated in accordance with CAA section 182(a)(3)(B), complies with all applicable statutory and regulatory requirements on a continuing basis.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

46 To properly implement the emissions reporting requirements, Emission Statement regulations should be coordinated carefully with the AERR and any associated guidance and specifications, the Modeling Guidance, and this guidance

. The required and optional data elements needed for inventories (described in Section 2.5.7 ) should be included as fields for reporting to the EPA

. Where the AERR/EIS has required fields, those fields should be required by the Emission Statement regulations. In addition, the Emission Statement regulation s should require ozone season emissions in accordance with the fi nal Ozone Implementation Rule.

Additional details o n developing emission statement regulations can be found in a dated, but still relevant guidance document titled , “Guidance on the Implementation of an Emission Statement Program (DRAFT) , ” available at https://www.epa.gov/air

- emissions

- inventories/implementation

emission

- statement

- program

. Where data elements to be collected are mentioned, users of that
g uidance should defer to the paragraph above, explaining that data elements should be coordinated with AERR/EIS requirements and the recommendations in this guidance for optional fields.



### 3.7 Maintenance Inventories Maintenance inventories reflect the emissions conditions associated with a NAAQS re designation to attainment following an initial area designation of nonattainment. Thus, the attainment year inventory for the maintenance demonstration should reflect emissions during the first year for which monitoring data showed compliance with the standard on which the state is basing their maintenance demonstration

. Otherwise, all characteristics of the attainment year inventory are the same as the base year inventory submitted with the implementation plan prior to attainment

. A n attainment year maintenance inventory is a component of a maintenance plan and is , therefore , submitted to the EPA as a SIP revision

. Thus all guidance in this document for completeness, temporal extent, spatial extent, public hearings, docu mentation, and summaries appl ies to these inventories.

The on

- road portion of the inventory for the relevant pollutants and precursors for the last year of the maintenance plan would be the motor vehicle emissions budget(s) required for maintenance areas b y 40 CFR 93.118(b). States may elect to also establish motor vehicle emissions budgets for the interim year or years for which they have submitted inventories or for the attainment year of the maintenance plan. Those decision s should be made through the in teragency consultation process that is required by CAA section 176(c)(4)(D) and 40 CFR 93.105.
Specific additional guidance for maintenance plan SIPs is also available in the memorandum titled , “Maintenance Plan Guidance Document for Certain 8

- hour Ozone A reas Under Section 110(a)(1) of Clean Air Act” (available at http://www.epa.gov/ttn/caaa/t1pgm.html )

. 

### 3.8 Projected Inventories The purpose of the projected inventories is to provide an emissions estimate for a year beyond the base
year

. T hese inventories are a lso called future

- year inventories. P rojected inventories will reflect the effects of control measures needed to reduce emissions and bring nonattainment areas and states into compliance with a NAAQS and regional haze rules

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

47 For ozone and PM 2.5 implementation, t he projected inventories are used for modeled attainment demonstrations , ROP/RFP plan s , and in maintenance plans to show that the attainment year inventory will not be exceeded in future years

. For the modeled attainment demonstration, the projected inventory represents the emissions needed to attain a NAAQS (according to the modeling) in a future
year. For the ozone ROP/RFP plan(s) , expected percent reductions of pollutants on specific timetabl es need to be shown

. Those the ROP/RFP plan(s) require only the “expected reductions” and not projected inventories, c alculating expected reductions involves estimation of emissions reductions, w hich can result in a projected inventory that shows the remai ning emissions after those reductions have occurred

. For regional haze, the proposed rule revisions of section 308(f)(6)(v) include the requirement for states SIPs to “provide for” a statewide inventory of estimates of future projected emissions. The purp ose of this projected inventory is to address the SIP requirement to focus on emission reduction measures that are designed to achieve reasonable further progress by 2028 by reducing emissions that lead to regional haze

. In addition for regional haze, the proposed rule revisions, if adopted, would eliminate an existing requirement for projecting emissions. T he existing section 308(g)(4) of the regional haze regulations (regarding progress reports in between SIP revisions) states that the analysis tracking t he change in emissions over the past 5 years must be based on the most recent u pdated emissions inventory, with estimates projected forward as necessary and appropriate to account for emissions changes during the applicable 5

- year period. The proposed revi sions of section 308(g) would remove mention of projecting emissions. The proposed tracking analysis would encompass emissions up to the year of the most recent NEI submission for all sources, and for relevant sources up to the most recent year for which t he EPA has provided a summary of emission information submitted by sources directly to the EPA.
Additional relevant provisions of 40 CFR part 51 must be considered for ozone, PM 2.5 , and regional haze implementation purposes. Subpart G of 40 CFR part 51 pro vides some foundational regulatory aspects of the control strategy development needed for creating projected inventories, including what SIPs must include with regard to control strategies and their associated inventories. In particular, 40 CFR 51.114 “Emi ssions data and projections” reads:
(a) Except for lead, each plan must contain a detailed inventory of emissions from point and area sources. Lead requirements are specified in §51.117. The inventory must be based upon measured emissions or, where measured em issions are not available, documented emission factors.
(b) Each plan must contain a summary of emission levels projected to result from application of the new control strategy.
(c) Each plan must identify the sources of the data used in the projection of emission s. In addition, 40 CFR 51.116 “Data availability” reads:Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

48 (a) The State must retain all detailed data and calculations used in the preparation of each plan or each plan revision, and make them available for public inspection and submit them to the Administrator at his request.
(b) The detailed data and calculations used in the preparation of plan revisions are not considered a part of the plan.
(c) Each plan must provide for public availability of emission data reported by source owners or operators or otherwise obtain ed by a State or local agency. Such emission data must be correlated with applicable emission limitations or other measures. As used in this paragraph, correlated means presented in such a manner as to show the relationship between measured or estimated am ounts of emissions and the amounts of such emissions allowable under the applicable emission limitations or other measures.
Thus, states should keep these requirements in mind as they develop their projected inventories so that these required SIP elements can be included.

3.8.1 Attainment Year Projected Inventories As listed in Table 4 , there are two possible attainment year project ion inventories

. The first is the attainment p rojected inventory for the NAA

. The second is the projected inventory for the modeled attainment demonstration

.
For ozone SIPs , a s described in Section 3.8.2 , one possible use of the attainment projected inventory for the NAA is for showing emissions reductions associated with an ROP/RF P plan. While it is conceivably possible to estimate the emissions reductions (rather than future year emissions inventories) required by the ROP/RFP plan, the most common way to estimate the reductions is by creating future

- year inventories and then calcu lating the difference between the ROP/RFP baseline and the attainment projected inventories for the NAA.

For PM 2.5 SIPs , the attainment projected inventory for the NAA is a required element of the SIP

. The detailed requirements for various aspects of this inventory are included in the regulatory text at 40 CFR 51.1008(a)(2) for Moderate areas and 40 CFR 51.1008(b)(2) for Serious areas

. For the attainment projected inventory for the NAA , a key difficulty can be calculating projected emissions for partial

cou nties, which would not necessarily be available from the modeling inventory. It may be possible to use the gridding aspect of modeled inventories to estimate emissions in partial counties for nonpoint and mobile sources. This issue is addressed more comple tely in Section 4.4.1

.
I n addition , the on

- road mobile portion of the attainment projected inventory for the NAA can serve as the motor vehicle emissions budgets for the ozone and PM 2.5 NAAQS. Specific requirements for motor

ve hicle emissions budgets for ozone (NOx and VOCs) and PM 2.5 (direct PM 2.5 , NOx and possibly VOCs, SO 2 and ammonia) can be found in 40 CFR 93.102(b). Since these budgets are required for transportation conformity purposes by 40 CFR 93.118(b), such inventorie s provide a convenient and consistent way to meet that requirement . In this case, the on

- road inventory should be created inEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

49 accordance with transportation conformity guidance ( http:/www.epa. gov/otaq/stateresources/transconf/ )

. Creating projected inventories includes a large number of data sources and requires estimates for stationary point, nonpoint, on
- road mobile, and nonroad mobile sources

. In addition, some areas may choose to use averag e fires to represent these highly variable (from year to year) and large contributors to emissions

. B iogenic sources are not generally forecast into the future because they are so dependent on meteorology

. Section 5 covers the details on projected inven tories

.
3.8.2 Rate of Progress and Reasonable Further Progress Emissions Reductions As described in Section 3.4 and the Ozone Implementation Rule , Moderate and above NAAs must have a plan for meeting a 15 pe rcent VOC emissions reduction (ROP plan) within 6 years after the NAA designation. Serious and above NAAs must also have a plan (RFP plan) to meet a requirement for an additional 3 percent per year VOC reduction (annual RFP) for each 3

- year period after th e initial 6 years (after the NAA designation) until the attainment date. In both cases, the VOC reductions can be substituted with NO X reductions when specific conditions apply. Serious and above areas may submit two separate plans since the annual RFP pla n is due 1 year later. Collectively, this guidance calls these plans the ROP/RFP plan(s).
In particular for the ROP requirement, an attainment year projected inventory for the NAA can also meet the ROP requirement by providing a projected inventory that sh ows the 15 percent VOC (or NO X , as applicable) reductions when compared to the ROP/RFP baseline NAA inventory . For Serious and above areas , an additional projected inventory may be needed to meet the ROP requirement. This is because the ROP requirement at 6 years can be earlier than the expected attainment date. In the case for Serious and above areas , ROP plans cannot use the projected attainment inventory for the NAA, but rather should use an inventory projected at the 6

- year interval.

To estimate the emi ssions reductions associated with ROP/RFP plans, air agencies should rely on the same techniques as for other projection purposes, which are described in Section 5

. When these reductions are calculated by creating projected inv entories, the on

- road portion of the inventories may also need to follow transportation conformity guidance ( http:/www.epa.gov/otaq/stateresources/transconf/ ) so that it can be used to set t he motor vehicle emissions budgets.
The emissions projections should include emissions growth where it occurs, emissions reductions intentionally included to meet the reductions needed for ROP/RFP, as well as emissions reductions occurring for other reason s (e.g., as co

- benefits from implementation of other NAAQS and from national mobile source or stationary source rules). These emissions projections will result not only in estimated reductions ( that are required to be included in the ROP/RFP plans ) , but al so in projected emissions inventories. Thus, the EPA recommends that summaries of these inventories are included in the ROP/RFP plan(s) to communicate the emissions reductions by comparing against the ROP/RFP baseline NAA inventory.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

50 3.8.3 Regional haze emission s reductions The requirement of 3 08(f)(6)(v) that states provide for estimates of future projected emissions supports the purpose of the SIP to focus on emission reduction measures that are designed to achieve reasonable further progress by 2028

. As descri bed in the preamble of the proposed regional haze rule, the state’s long

- term strategy to address regional haze must include enforceable emission limitations.” The EPA expects that the estimates of future projected emissions to meet the requirements of 308 (f)(6)(v) would therefore include the projected impacts of these enforceable emission limitations.
The proposed revision to the Regional Haze Rule does not assume that all sources in a state must be subject to an analysis of the four factors laid out in 30 8(f)(2)(i), but subsection 308(f)(2)(v) requires the state to identify the sources considered by the state in developing its long

- term strategy and the criteria used to select the sources considered. As proposed, o nce the emission reductions measures for t hese

sources are identified pursuant to the four

- factor analysis , the emission reductions from th ose measures would be part of the projection of end

- of

- implementation period emissions (2028, 2038, etc.) needed to
set the reasonable progress goals. The emis sions projection techniques provided in Section 5 below can provide the necessary technical guidance to support states in project ing their future emissions

. 

### 3.9 Public Hearings For ozone and PM 2.5 implementation, some e missions inventories are considered a par t of the SIP under the CAA (see s ections 172(c)(3), 182(a)(1)(A) and 182(a)(3)(A) ) , and in this guidance we have called these planning inventories . Thus, for ozone and PM 2.5 SIPs , detailed emissions inventories data are required to be included in the publi c participation associated with SIPs as specified in CAA section 110(a)(2)

. For regional haze, the detailed emissions inventory data are not expected to be a part of the information provided for a public hearing on the regional haze SIP

. If emissions inven tory information (but not the detailed data) is included as part of a SIP submission, the emissions information in the SIP submission stills need to be included as part of the information provided as specified in CAA section 110(a)(2)

. In addition, 40 CFR 51.102 (a) further explains that a public hearing requirements means “The State must hold a public hearing or provide the public the opportunity to request a public hearing.” Thus, the phrase “ or provide the opportunity to request” means that it is possib le that public hearings on inventories will have no one request a public hearing 18

.
T here are policy reasons that support the need for detailed emissions inventories data to be approved with the SIP

. Some emissions inventories must be used as a basis for o zone RFP plans for areas classified as Moderate or above

. Additionally, all NAAs seeking redesignation to attainment will rely on an emissions inventory for purposes of submitting a maintenance plan under CAA s ection 175(A)

. B ecause the emissions inventori es and projections play such a fundamental role in determining the reductions

18 A public hearing must be offered for every SIP submittal , but a hearing does not need to actually occur if no one requests a hearing. The detailed requirements for public notice and hearings are given in 40 CFR 51 .102. See also Attachment B of “Regional Consistency for the Adminis trative Requirements of State Implementation Plan Submittals and the Use of Letter Notices,” EPA memorandum dated April 6, 2011, from Janet McCabe, Deputy Assistant Administrator for the Office of Air & Radiation to the Regional Administrators, www.epa.gov/airquality/urbanair/sipstatus/docs/FINALSIPGuidelinesSubLtrsPN.pdf

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

51 necessary to attain and maintain the standard, they need to receive full public scrutiny and be formally incorporated into the SIP.
As explained in the final Ozone SIP Requiremen ts Rule, the EPA is no longer advising states to follow our existing September 29, 1992, guidance titled, ‘‘Public Hearing Requirements for 1990 Base

- Year Emissions Inventories for Ozone and Carbon Monoxide Nonattainment Areas ” in implementing certain SIP adoption and submission procedures for the emissions inventory requirements under CAA sections 182(a)(1) and 182(a)(3)(A) for purposes of the 2008 ozone NAAQS. In that guidance, the EPA indicated it could provide states with a time

- limited “ de minimus” def erral of the CAA’s state p ublic hearing requirement for t he emissions inventory SIP revi sion until the inventory needs had “regulatory significance

. ” As there is nothing in the CAA provisions that provides for waiver or delay of the public notification and hearing requirements specified in CAA section 110(a) de minimus or otherwise, we no longer believe it is appropriate to advise states to follow the 1992 guidance. W e remind states that the EPA’s implementing regulations at 40 CFR part 51 (Requirements for Preparation, Adoption, and Submittal of Implementation Plans) provide flexibility for states to streamline SIP

- related public notification and hearing procedures (for example, only holding a public hearing if one is requested, per 40 CFR 51.102), and we e ncourage states to take advantage of those provisions in meeting the emissions inventory requirements under CAA sections 182(a)(1) and 182(a)(3)(A).

For areas classified as Moderate or above, the state would need to provide the EPA with verification that a public hearing was offered for the emissions inventory for any emissions inventory SIP revision at the time the state submits the emissions inventory SIP.

In instances where a public hearing is held for the emissions inventory SIP revision, the EPA clari fies here what is required by EPA regulations to be published and present for public review

. Because emissions inventory data can be voluminous, it is common to summarize that data for public hearing purposes

. The EPA does not interpret 40 CFR 51.102 to re quire that at a public hearing, held in accordance with that provision, every database entry related to the emissions inventory must be summarized, presented, and/or made available

. Rather, the EPA expects that , in general, emissions inventory summaries wo uld be the primary source of information for public review, so long as the detailed emissions inventory data are available to the public in accordance with the C AA and EPA regulations. Air agencies must comply with 40 CFR 51.102(d)(2), and 40 CFR p art 51 , Appendix V.

At a minimum, the state should include summaries of the actual emissions

. The EPA recommends using the same tables as those recommended in the EI Guidance for inclusion in the SIP documentation for the purpose of the p ublic review (see Section 3.10.3 of th is guidance “What to Submit”).



### 3.10 Submit Inventory Parts of SIP to the EPA 40 CFR p art 51 contains the requirements for SIPs, and many general provisions in Part 51 impact the requirements for emissions inventory SIPs

. Section 3.10.1 summarizes the applicable regulations

. In addition, t he two key concerns for submitting inform ation on inventories are: (1) how to submit,Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

52 including the format and (2) what to submit. Th ese concerns are addresse d in Sections 3.10.2 and 3.10.3 , respectively.

3.10.1 Regulatory Requirements in Addition to Implementation Rules The general regulatory requirements for SIP submissions are available in several subparts o f 40 CFR part 51 that have an impact on the emissions inventory SIPs

.

 Subpart F

– Procedural Requirements

o §51.102 Public hearings (see Section 3.9 above)

o §51.103 Submission of plans, preliminary review of plans: Cites Appendi x V as the source of the requirements that constitutes an official plan submission.

 Subpart G

– Control Strategy

o §51.112 Demonstration of adequacy This section requires a presentation of emissions levels expected to result from implementation of each measu re of a control strategy ( in the modeled attainment demonstration).

o §51.114 Emissions data and projections This section has three subsections : (a) requires a detailed inventory of emissions from point and area sources that are based on measure emissions or , where measured emissions are not available, documented emission factors ; (b) requires that the plan contain a summary of emission levels projected to result from application of the new control strategy ; and (c) requires that each plan must identify the sources of the data used in the projection of emissions

. o §51.116 Data availability Subsection (c) requires that each plan must provide for public availability of emission data reported by source owners or operators or otherwise obtained by

a s tate or loca l agency

. It also requires correlation of emission data with applicable emission limitations or other measures.

 Subpart Q

– Reports

o §51.322

– Sources subject to emissions reporting This section points to Subpart A, which is the AERR

. o §51.323

– Reportable e missions data and information This section also points to Subpart A

.

 Appendix V

– Criteria for Determining the Completeness of Plan Submissions

o 2.2 Technical Support

. This subsection of Appendix V lists various parts of the SIP that must be included that c an be met as part of the EI SIP, including:
(b) Identification of the location of affected sources included the EPA attainment/nonattainment designations of the locations and the status of the attainment plan for the affected area(s)

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

53 (c) Quantification of the changes in plan allowable emissions from the affected sources; estimates of changes in current actual emissions from affected sources or, where appropriate, quantification of changes in actual emissions from affected sources through calculations of th e differences between certain baseline levels and allowable emissions anticipated as a result of the revision.
(e) Modeling information required to support the proposed revision, including input data (which includes emissions).

o 3.2 Paper Plan Submissions. This section addresses the EPA’s voluntary guidelines for which states are requested to adhere for paper and electronically formatted submissions.

3.10.2 How to Submit Inventory Parts of a SIP The EPA generally encourages air agencies to provide all parts of the SIP related to emission inventories using digital media

. For the Ozone SIP Requirements Rule, the preamble specifically indicates that “states must make available the inventory data to the EPA as electronic files in ... electronic media, such as FTP, zip dr ives, or DVDs.” In most cases, it’s simply best practice to provide this information digitally

. Because of the challenges that can arise with the use of formats that are supported by one agency and not the other, air agencies should provide documentation a t least in formats that are readily transferrable, such as PDF for documentation files

. Other formats can also be considered and agreed upon in advance, and such details would be ideal to be included in an IPP.
When paper plans are submitted, some guidelin es provided in 40 CFR part 51 , Appendix V apply

. In accordance with s ection 3.2(a) of A ppendix V , the EPA requires that whe n submitting one paper plan , it must be accompanied by an electronic duplicate of the entire paper submission, preferably as a word

s earchable document format (PDF).
For the format, the above information is provided as guidance

. T here are no specific formatting requirements added by this guidance for the inventory data, emissions summaries, or documentation submitted as part of the SIP

. Requirements are included in implementation rules, and the ozone, PM 2.5 , and regional haze implementation rules do not specify required formats for submitting inventory information

. For ozone and PM 2.5 , however, the data elements required for submitted em issions inventories are to use the elements required by the AERR.
Currently, the AERR data format does not directly support the use of partial counties. Thus, inventories with partial counties are not currently able to use the EIS formats and states would need to use some identifier in the format to denote partial counties.
The following provides a list of best practices that the EPA encourages air agencies to use when submitting the Inventory Parts of a SIP:Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

54  In accordance with Subpart A, detailed inventor y data are required as part of emission inventory SIPs

. When providing full detailed inventory data (i.e., facility

- SCC

- pollutant data for point sources or county

- SCC

- pollutant data for nonpoint sources):

o Use the data elements required by the AERR. This is required by the ozone and PM 2.5 implementation rules.

o Coordinate with your Regional office about what format is going to be used

. If EIS format is used, consider submitting this to the EIS, but first contact the EPA NEI program to make sure any such submi ssion will not conflict with other inventories already submitted to the EIS.

o If not using the EIS format, use Excel®, Access® or a rigorous delimited text format

. For a delimited text format, make sure that the text fields have double quotes and that the d elimiter chosen (e.g., a tab) does NOT appear in any of the text fields, since this will prevent the delimited dataset from being imported easily into other data systems.

 For documents, use a readily available word processor format (e.g., Microsoft Word®) or convert the document to PDF format.

 At times , it can be very time consuming to convert tables from a spreadsheet and insert them into a word processor , especially if the information changes and has to be updated

. The guidance below recommends a lot of s ummary tables

. Rather than cut/pasting into a text file, states may consider creating a spreadsheet with individual worksheets (tabs) labeled as each table included in the document

. Then, just reference those tables/tabs from document

. This can be done wit h words only (e.g., “see Table 1 in Excel file”) or using a more sophisticated data link between the word processor and spreadsheet software.

3.10.3 What to Submit With regard to exactly what to submit, the information provided here provides guidance on what wou ld be acceptable in most cases

. T he list of tangible data items and documentation forms the basis of what the EPA will review and ultimately approve for a SIP

. Table 11 provides the suggested inventory elements of a n Emissions I nv entory SIP and indicates whether they are relevant for ozone, PM 2.5 , and/or Regional Haze SIP s

. Refer to the tables in Section 2.3 for more information on which elements are required and which are optional

. This section (and Table 11 ) does not include RFP inventories since those are submitted with a separate ROP/ RFP plan

. Similarly, it does not include information needed for a modeling attainment demonstration submittal to the EPA , with the exception o f the inclusion of statewide inventory summaries for ozone and PM 2.5 SIPs for areas that have modeled attainment demonstrations as part of their SIP requirements.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

55 Table 11 : Suggested Elements of a n Emissions inventory SIP Document SIP Planning Inventory Documentation Element Ozone PM 2.5 Haze Background: Includes key elements explained in this guidance, such as the nature of the air quality problem (or arrival at attainment status for maintenance SIPs), priority source categories and point sources, pollutants covered, spat ial extent, and other key inventory aspects

. Y

 Overall base y ear e missions s ummaries: All emissions are for relevant pollutants only

. Data categories would minimally be point, nonpoint, nonroad mobile, and on

- ro ad mobile, and fires, though more detailed categories are acceptable

. Biogenic sources and other sources can optionally be included as well, and may be required by Regional office s for areas doing modeled attainment demonstrations. See Table 12

 Overall p rojected a ttainment year e missions s ummaries: The
same as the base year summaries except using the attainment projected inventory for the NAA. Required for PM 2.5 SIPs. These summaries are optional for the ozone Emi ssions Inventory SIP

. For ozone and when developed in accordance with transportation conformity guidance, the on

- road portion also can set the motor vehicle emission budgets for VOC and NO X . If not provided in the Emission Inventor y SIP, the summaries woul d be needed in the Modeled Attainment Demonstration. See Table 12 n/a

 Overall recent year emissions summaries compared to projected emissions: All emissions are for relevant pollutants only. Data categories would minimally be point, nonpoint, nonroad mobile, on

- road mobile, and fires. See Table 12 Stationary Point Sources:

 Introduction with more detailed documentation of the emissions from stationary point sources, in cluding the point source emissions threshold, how the point sources were identified, how emission estimates were made including emission factors, activity data, and control assumptions. Y

 This section includes additional point source emissions summaries

. See Table 13 Stationary Area (Nonpoint) Sources:

 Introduction with more detailed documentation of the emissions from stationary nonpoint sources, including how the nonpoint sources were identified, the model version used, which sources were not addressed and why, how partial county emissions were estimated, and how emission estimates were made including models or tools, emission factors, activity data, and control assumptions. Y

 This section includes additio nal nonpoint source emissions summaries

. See Table 14Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

56 SIP Planning Inventory Documentation Element Ozone PM 2.5 Haze Nonroad Mobile Sources

 Introduction with more detailed documentation of the emissions from nonroad mobile sources, including how the nonroad mobile source s were identified, which sources were not addressed and why, how partial county emissions were estimated, and how emissions estimates were made including model version , source of input data, input and output data files, and any post

- processing methods used to develop the inventory

. Y

 This section includes additional nonroad source emissions summaries. See Table 14
On

- road Mobile Sources

 Introduction with more detailed documentation of the emissions from on

- ro ad mobile sources, the model and version used, how partial county emissions were estimated, and how emissions estimates were made including sources of input data, input and output data files, and any post

- processing methods used to develop the inventory

. Y

 This section includes additional on

- road source emissions summaries. See Table 14
Other Sources

 If applicable, a description of other sources in the emissions inventory not included and reasons why they are not included. Y

 If applicable, t his section includes summaries of other sources of emissions

. See Table 14 Demonstration of Public Hearing: A brief description of the public hearing process, a summary of the re sults, and any other relevant materials

. The purpose of this section is to provide evidence for the public hearing and what the air agency learned through the process. Y Y N

Table 12 provides the summaries to include in the backg round section

. In the table, “data category” is consistent with the definition provided in Table 11 and Section 2.5.1

. If both the base year inventory and the attainment projected inventory are include d in the background, then the same summaries should generally be provided for both.

Table 12 : Summaries to include in the background
Emissions Summaries Ozone PM 2.5 Haze Annual baseline, recent year e missions , projected emissions , and emissions difference for the state by data category . The baseline emissions may from the original SIP may be used. Y
Annual base year emissions and/or average season day emissions for the NAA by data category Y + Annual base year emissions and/o r average season day emissions for the NAA b y data category and county ( or partial county) λ Y +
Ozone s eason day base year emissions for the NAA by data category YEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

57 Emissions Summaries Ozone PM 2.5 Haze Ozone s eason day base year emissions for the NAA by data category and county (or partial county) ∆ Y

+ Either annual or season

- day emissions need to be reported (but not ne cessarily both), depending on the temporal basis used for the emissions in the SIP . For areas that have nonattainment for both the annual standard and the 24

- hour standard and are using average

- season
- day inventory for their 24

- hour SIP, then summaries of both temporal resolutions would be needed

. ‡ For SIPs that include air quality modeling, this section can include both summaries of the planning and the modeling inventories

. Since modeling domains are usually much larger, multi

- state areas, the resolutio n of the modeling inventory summaries depends on the modeling guidance and the preferences of the Regional office

. One option is to include county

level detail for the state(s) included in the NAA , but state

- level detail for surrounding states. λ Partial c ounty emissions can be included rather than, or in addition to, full county, where applicable.
∆ Providing both the county and partial county could provide more flexibility for states when submitting periodic inventories.
Table 13 provides the recommended minimal contents for summaries to include in the point sources section

. If both the base year inventory and attainment projected inventory are included in the background, then the same summaries should generally be provided for bo th.

Table 13 : Summaries to include in the point sources section
Emissions Summaries Ozone PM 2.5 Haze Annual recent year emissions , projected emissions, and emissions difference for each point source as a facility total, within the state. Y Annual base year emissions and/ or PM 2.5 average season day base year emissions for each point source as a facility total, within the NAA

. Y
Ozone season day base year emissions for each point source as a facility total, within the NAA

. Y These summaries should include: the county, Agency Facility ID, plant name, physical address, total control efficiency, key control devices, NAICS code, and actual and/or projected emissions. Other summaries may be included as well, such as by SCC or oth er fields that are necessary to describe the inventory effectively

. The Agency Facility ID or some other ID should be included that can easily map to the EPA facility records in EIS. This can be more difficult when air agencies change their Agency Facility IDs.

Table 14 provides the recommended minimal contents for summaries to include in the nonpoint and mobile sources sections

. If both the base year inventory and the attainment projected inventory are included in the background , then the same summaries should generally be provided for both

.

Table 14 : Summaries to include in the nonpoint and mobile sources sections
Emissions Summaries Ozone PM 2.5 Haze Annual recent year emissions , projected emissions, a nd emissions difference by county and SCC (or SCC group ‡ ), within the state. Y Annual base year emissions and/or average season day emissions by county and SCC (or SCC group ‡ ), within the NAA. Y Ozone season day base year emissions by county and SCC (or SCC group ‡ ), within the NAA

. YEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

58 For county and emissions processes reported that have reductions associated with rules, these summaries should include any control efficiencies or rule effectiveness assumed and actual and/or projected emissions . Proje cted attainment year emissions summaries may also be required for areas performing modeled attainment demonstrations. ‡ See additional information below on SCC groups

. SCC groups for on

- road and nonroad mobile sources can be useful in limiting the size o f summaries without much loss of information

. For example, SCC groups can be formed by vehicle type and fuel, dropping the road classifications

. Vehicle types can be further grouped into light duty and heavy duty

. The amount of grouping appropriate depends on what a particular summary and SIP are trying to communicat e

. SCC groups can be suggested as appro priate by Regional office s or air agencies as part of the consultation for what will be included in the emissions inventory SIP.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

59 

## 4 Developing Current Emissio ns inventories This section covers the decisions that states will need to make regarding any “current” emissions inventory, including a base year NAA or state inventory, RFP baseline inventory, periodic inventory (for

ozone or regional haze ), or maintenanc e inventory

. As a reminder, all inventories described in this section are inventories of actual emissions; these inventories do not contain emissions based on potential to emit nor allowable emissions. In accordance with 40 CFR 51.5(b), states are urged to use applicable, state

- of

- the art techniques for estimating emissions.



### 4.1 Inventory Years A fundamental step in creating a base year inventory is the choice of inventory year

. The Ozone, PM 2.5 and R egional H aze I mplementation R ules include specific language r egarding the choice of inventory years, and those regulatory requirements supersede any guidance provided in this section

. Since the purpose of the base year inventory is to represent relatively current emissions conditions, there is a general preference t o use as recent a year as practical

. T his means that the year of emissions estimates is usually several years earlier than the year in which the inventory work is done , given the time that it takes to compile an emissions inventory (for example, an invento ry with 2014 emissions may not be compiled until 2016)

. The prima ry considerations in choosing a baseline inventory year as c overed in this guidance are : (1) the implementation rule requirements, (2) transportation conformity requirements , and ( 3 ) the avai lability of data

. This is in contrast to inventories used for air quality modeling, for which meteorology , and availability of ambient data are the primary considerations , with inventory availability secondary

. This is because the meteorological conditions selected should be associated with ozone formation that is representative of either the ambient data relied upon for designation to nonattainment or recent ambient data, as appropriate. C hoosing a year based solely on inventory availability could result i n choosing an inappropriate year (considering ambient measurements and the meteorology that led to those measured concentrations)

. As a result, the base year(s) used in the planning inventories can be different than the modeling base year and associated mo deling inventory.

4.1.1 Ozone baseline year For ozone, states should become familiar with the specific rule requirements

. The 2008 O zone I mplementation R ule in 40 CFR 51.1115(a) specifies that the “inventory year shall be selected consistent with the baseline ye ar for the RFP plan as required by Section 51.1110(b), which reads as follows:
(b) Baseline emissions inventory for RFP plans. For the RFP plans required under this section, at the time of the designation for the 2008 ozone NAAQS the baseline emissions inv entory shall be the emissions inventory for the most recent calendar year for which a complete triennial inventory is required to be submitted to EPA under the provisions of subpart A of this part. States may use an alternative baseline emissions inventory provided the state d emonstrates why it is appropriate to use the alternative baseline year, and provided that the year selected is between the years 2008 to 2012. All states associated with a multi

- state nonattainment area must consult and agree on a sing le alternative baseline year.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

60 Thus, for the 2008 ozone standard , the 2011 inventory year is the presumed inventory year

. Guidance on the considerations for using an alternative baseline year is provided below in Section 0

.
Th e consideration of transportation conformity requirements is important because the rule has its own language a bout selecting a base year

. The applicable section of the rule is 40 CFR 93.119(e), which reads:
(e) Baseline year for various NAAQS . The baselin e year is defined as follows:

... (4) The most recent year for which EPA’s Air Emissions Reporting Rule (40 CFR Part 51, Subpart A) requires submission of on

- road mobile source emissions inventories as of the effective date of designations, in areas designat ed nonattainment for a NAAQS that is promulgated after 1997.
This requirement impacts the 2008 and 2015 ozone standards

. For convenience, OTAQ provides an online table that lists the appropriate base year for use for transportation conformity purposes ( see https://www.epa.gov/state

- and

- local

- transportation )

. Unlike the ozone implementation rule, the transportation conformity rule does not include a provision for an alternative baseline year; thus, states that wish to select an alternative year are advised to consult with their Regional office as part of their SIP development

. Lastly, t he consideration of “availability” is simply what data are (or will be) available to the air agency during t he time alloted for SIP preparation

. Often, the triennial NEI year inventories ( as described above ) are useful starting points for meeting the various “current” inventory requirements associated with SIPs

. For these triennial NEI years, states are already required to have prepared and provided to the EPA inventories of criteria pollutants and precursors as well as model inputs for on

- road and nonroad mobile

sources

. In some cases, the states have submitted their data to the EPA, but the complete NEI is not yet available because there is a 6

- 12 month lag between when the emissions have been submitted and when the inventory is released by the EPA

. In this case, the state should make every effort to use the most currently available information and incorporate a ny new information that is made available by the NEI release at the earliest practical time.

Other benefit s of using an NEI year is that NEI data are available for all states , and information from more than one state may be needed for attainment demonstrat ion modeling purposes. Additionally, other data needed for modeling (e.g., meteorology and SMOKE inputs) are more likely to be available for the triennial NEI years.

4.1.2 PM 2.5 For PM 2.5 , states should become familiar with the specific rule requirements

. The PM 2. 5 SIP Requirements R ule at 40 CFR 51.1008(a)(1)(i) states : (i) The inventory year shall be one of the 3 years for which monitored data were used for the designations or another technically appropriate year if justified by the state in the plan submission

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

61 For the 2012 PM 2.5 NAAQS, the EPA used ambient data from 2011 through 2013 to designate PM 2.5 NAAs ; thus any of these three years can be used as the baseline year

. The idea behind this connection is that the inventory should represent the emissions condi tions in the local area associated with the nonattainment problem. Given this purpose, situations may arise where the most applicable available inventory year is not one of these 3 ambient

- data years.
Two examples of such situations are offered here. In t he first, a newer inventory may be advisable. Because of time that it takes for designations to occur and the period allowed for SIP submittal, a significant increase in emissions could occur between the designation period and the time SIPs are submitted. This has occurred in some areas due to oil and gas development, for example. In th is case, it may be more appropriate to use an inventory year that is newer than one of the 3 years of data used for designations, to represent the higher emissions or differe nt source mix associated with a more recent year . Another example is that in an area where mobile sources are a small part of the emissions inventory, emissions may not have changed much from a year prior to the 3

- year period of ambient data. In this case, an available inventory prior to one of the 3 years may sufficiently represent the inventory. In both cases, the air agency preparing the SIP should explain these issues as part of its justification for not using one of the three years. The inventory basel ine year is the same year used for the RFP baseline year

. In addition, states must meet quantitative milestone requirements as described in 40 CFR 51.1013(a)

. Within the 3 years available for choosing a base year , a large source of emissions may be reduced . If a state chooses a year after those reductions have occurred, then the state would not get the benefit of those reductions in meeting their RFP and quantitative milestone requirements. In addition , if those emissions were a key part of the nonattainmen t problem, then the choice of the later year would not follow the guidance that the year selected be representative of the cond itions leading to nonattainment. The considerations for availability of emissions for PM 2.5 planning inventories are the same as for ozone as described in the previous subsection.

4.1.3 Regional Haze As described in Section 2.3.3 , the year of the baseline inventory has previously been set . For the initial Regional Haze SIP s, the year used should have fallen be tween and inclusive of the 2000 to 2004 baseline period. Most areas used 2002 as their baseline inventory year in their initial SIPs based on an OAQPS memo about this issue (see http://www3.epa.gov/ttn/naaqs/aqmguide/collection/cp2/ 20021118_wegman_2002_base_year_emission_sip_planning.pdf ).

The proposed Regional Haze Rule revision addresses what states must do for subsequent plannin g periods, and this proposed revision would require that states create and use a recent year inventory as part of their SIP analysis. As described in Section 2.3.3 above , the 5

- year progress reports and 10

- year SIP revisions in clude specific language regarding the inventory year to use for developing those plans , which we address here in more detail.
For the progress reports, an inventory is used to compare back to the most recent previous inventory from the previous SIP revisio n. The proposed analysis year for this comparison is the most recent yearEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

62 for which the state has submitted emission inventory information to the EPA in compliance with the triennial reporting requirements of the AERR. In addition, the proposed rule revisi on states the following: “With respect to sources that report directly to a centralized emissions data system operated by the Administrator, the analysis must extend through the most recent year for which the Administrator has provided a State

- level summar y of such reported data or an internet

- based tool by which the state may obtain such a summary. ” This lat ter requirement refers (at least) to the direct reporting of the CEM data for EGU sources. Thus, the emissions year(s) for the progress report tracking anal ysis would include the most recent NEI year that had been reported by the state and any newer EGU (or other) data available through direct facility reporting.

For the 10

- year SIP revisions, an inventory is used as a starting point to examine future e missions reductions and assess expected progress on visibility improvements. Similar to the progress report requirement, the proposed rule revision at 40 CFR 308(2)(f)(iv) would require this starting year to be the most recent year for which the state has submitted emission inventory information to the EPA in compliance with the triennial reporting requirements of the AERR. This section also allows for a different year if “the State adequately justifies the use of another inventory year.” Section 4.1.4 provid es more information on considerations for choosing an alternative year.

4.1.4 Considerations for choosing an alternative base year For both ozone and PM 2.5 SIPs and regional haze , the governing implementation rules allow states t o choose a different year than one of the presumptive years as described in the subsections above

. In general, states seeking to use newer inventory years will be easily able to justify that choice on the basis of improvement in meeting the CAA requirement for a “current” inventory (see CAA 172(c)(3) for PM 2.5 and 182(a)(1) for ozone). It is presumed that because of ongoing control programs for mobile and stationary sources, which get additional reductions each year, more recent year inventories will reflec t lower emissions levels.

Another common reason for choosing a different base year include s a desire to have the base year for planning inventories consistent with the base year used for modeling inventories

. The modeling base year is determined in part by meteorology that is conducive to formation of ambient levels of a NAAQS pollutant that are above the NAAQS. Other reasons may also exist for choosing a different year, and these should be provided as part of SIP documentation. Ideally, any such decisions would be made in the planning phase of SIP development, in consultation with the Regional office.



### 4.2 Pollutants and Pollutant Precursors to Include in Inventories This section describes the pollutants and precursors that should be includ ed in the planning in ventories for the ozone, PM 2.5 , and regional haze rules

. Pollutants for ROP/RFP inventories are also described in Section 3.4 .2

. Because many sources emit more than one of the precursor pollutants, and because the precursor pol lutants have the potential to be transported across state boundaries, the EPA encourages air agencies to develop inventories fo r all pollutants , where possible , to support integrated, regional

scale modeling and control strategy development for ozone, PM 2. 5 , and regional haze.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

63 Section 172(c)(3) of the CAA requires “the relevant pollutant or pollutants” to be included in inventories for SIPs

. The ozone, PM 2.5 and regional haze implementation rules include specific language regarding the pollutants and precur sors to be included, and those regulatory requirements supersede any guidance provided in this section.

For the 8

- hour ozone NAAQS, the pollutants to be inventoried are VOC and NO X . The ROP/RFP baseline NAA inventory for ozone should also include VOC and NO X . For the PM 2.5 NAAQS, the pollutants to be inventoried are primary emissions (including both the filterable and condensable portions ) of PM 10 and PM 2.5 , and emissions of SO 2 , NH 3 , VOC, and NO X . The EPA has finalized the requirement that PM 10 emissions are to be reported with the PM 2.5 inventories because PM 10 emissions are often used as the basis for calculating PM 2.5 emissions. F or regional haze, the pollutants to be inventoried include all of the pollutants and precursor pollutants identified for ozon e and PM 2.5 , excluding CO

.
4.2.1 Condensable PM emissions As mentioned previously, the AERR identifies reporting requirements for the implementation rules

. I n the past , a source of confusion has been the AERR requirement for reporting primary PM 10 and primary PM 2.5 emissions , which states , “ As applicable, also report filterable and condensable components. ” The AERR also defines c ondensable PM as:
Material that is vapor phase at stack conditions but which condenses and/or reacts upon cooling and dilution in the am bient air to form solid or liquid PM immediately after discharge from the stack

. Note that all condensable PM, if present from a source, is typically in the PM 2.5 size fraction and, therefore, all of it is a component of both primary PM 2.5 and primary PM 10

. While the wording in the AERR is clear that the EPA expects reporting of all components of primary PM including condensable portion (and as individual components) , the rule does not clarif y “as applicable” by identifying those sources that are expected t o have condens able PM

. To clarify this issue , Table 15 provides a list of source types for which condensable PM is expected by the AERR

.

Table 15 : Source types expected to include condensab le PM

EIS Sectors (and subsectors) Subsectors and Degree of Condens a ble Data

Categories Commercial Cooking High Nonpoint Fuel Combustion

– Electric Generating Utilities

– all fuel types Low, except Gas Turbines are negligible Point
Fuel Combustion

– Ind ustrial Boilers

– all fuel types Point Nonpoint

Fuel Combustion

– Commercial/Institutional

– all fuel types Moderate and depends on control technology Point

Nonpoint
Fuel Combustion

– Residential

– Oil, Natural Gas, Other Significant Nonpoint Industria l Processes

– Cement Manufacturing (Kilns) Low PointEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

64 EIS Sectors (and subsectors) Subsectors and Degree of Condens a ble Data

Categories Industrial Processes

– Chemical Manufacturing (Fuel Fired Process Heaters, Carbon Black Fuel Fired Furnaces and Dryers, Charcoal Manufacturing, Fuel Fired Ore Calciners, Ammonia Production Fuel Fired Reformers, Fuel Fired Incinerators, other fuel fired equipment) Low

– Moderate, depends on industry Point

Industrial Processes

– Ferrous Metals (Silicon Metal Electric Smelting Furnaces, Electric Arc Furnaces, Electric Induction Furnaces, Basic Oxygen Fu rnaces, Iron & Steel Pouring/Casting, Foundry Cupolas, fuel fired equipment) Primary metals: High, others Low

- Moderate Point

Industrial Processes

– NEC + (Brick Manufacturing Kilns, Lime Manufacturing Kilns, Glass Manufacturing Furnaces, Mineral Wool Bl ow Chambers, Fuel Fired Process Heaters, Coke Manufacturing Ovens, other fuel fired equipment) Coke Ovens: High, others Low Point

Industrial Processes

– Non

- ferrous Metals (Aluminum Ore Electro

- reduction, Smelting Furnaces, Zinc Electrothermal Furnaces, Pouring/Casting, Rolling/Drawing/Extruding, Fuel Fired Process Heaters, other fuel fired equipment) Primary metals: High, Asphalt electrode facilities: High, Drying: High; Others: Low Point

Industrial Processes

– Oil & Gas Production (Gas Well Dehydrators , Gas & Oil Well Heaters, Fuel Fired Compressor Engines, Heater Treaters, Process Heaters, Steam Generators) High Point Nonpoint

Industrial Processes

– Petroleum Refineries (Process Heaters, Catalytic Cracking Units, Coke Calciners, Flares, Process Gas I ncinerators, other fuel combustion) Low Point

Industrial Processes

– Pulp & Paper (Recovery Furnaces, Lime Kilns, Paper Machine/Pulp Dryer, Sawmill Sanding: Cyclone Exhaust, Particleboard Cooler or Dryer, Smelt Dissolving Tank, Particleboard Presses) Mode rate

– High Point

Waste Disposal (Landfill Flares, Other Landfill Gas Waste Gas Combustion, Incinerators) Low

- Moderate Point

For stationary point and nonpoint sources, the EPA recognizes th at emission factors for condensa ble PM are limited, as well as emission factors for many industrial sources of filterable PM 2.5 . Resource constraints for many years have made it infeasible for EPA to conduct sufficient testing programs to populate all of the necessary emission factors

. Nevertheless, state and local a ir agencies and their facilities are responsible for estimating emissions from sources required by the AERR.
In response to this issue, the EPA continues to work to help state and local air agencies meet their responsibilities. The EPA has devised a mecha nism to more readily collect source test data for use inEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

65 developing improved emission factors

. More information on this approach can be found at https://www .epa.gov/electronic

- reporting

- air

- emissions/electronic

- reporting

- tool

- ert

. The EPA invites industry, state , local and tribal agencies to provide source test data they may collect during the preparation of PM inventories to support the development of emiss ion factors.
Additionally, the EPA has used available existing emission facto rs to develop a “PM augmentation tool ” (see https://www.epa.gov/air

- emissions

- inventories/pm

- augmenta tion )

. The tool uses ratios of the most applicable available emission factors to calculate one PM component from another

. In the absence of improved PM condensable emission factors or facility

- specific source data, inventory developers can use this tool t o calculate PM condensable emissions from filterable PM 2.5 or total PM 2.5 emissions.

Condensable PM emissions are not an issue associated with mobile sources. The MOVES model used for these sectors produces primary emission estimates for PM, including par ticle components (e.g., elemental carbon and organic carbon) and gaseous hydrocarbons (e.g., VOC, non

- methane organic gases). These pollutant metrics would include both “filterable” and “condensable” PM. These are currently not separable in MOVES, and fo r SIP inventory purposes, they can be reported as they are output from MOVES without additional modification.

4.2.2 Regulatory D efinition of VOC The EPA’s current regulatory def inition of VOC (40 CFR 51.100 (s) ) excludes constituents considered to be negligibly r eactive in atmospheric photochemistry

. These include methane, ethane, methylene chloride, 1,1,1

- trichloroethane (TCA), several Freon compounds, acetone, perchloroethylene, and others . States should use the CFR reference above to find the complete list. Ove r time, 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; for example, methane impacts on ozone ha v e been observed in areas of high methane emissions associated with oil and gas development

. The emission factors used to estimate organic emissions generally account for nonmethane hydrocarbons (NMHCs)

. For SIP purposes, state , local and tribal agencies s hould report VOC as defined by the EPA (40 CFR 51.100 (s) )

. This is the case regardless of the treatment of methane for modeling inventories, which is addressed in more detail below

.
4.2.3 Treatment of M ethane The treatment of methane in emissions inventories may be relevant for emissions used in modeled attainment demonstrations. Methane is not expected in other planning inventories associated with SIP s

. This section is included to explain the context for which methane emissions can be important and to specifical ly note its possible relationship to the VOC emissions that are associated with SIP planning inventories. In some cases, air agencies interested in considering non

- VOC

- based estimates of methane in their modeling inventories may optionally choose to consid er methane as part of non

- modeling inventories as well.
The air quality models used for modeled attainment demonstrations use methane as one of the modeled pollutants . However, these models have typically used a fixed concentration of methane thatEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

66 does not change. Thus, typical applications have not used methane emissions from emissions inventories.
Unlike the air quality models, the emissions processing steps to prepare emissions inventories for use in air quality models do compute methane emissions

. M etha ne has traditionally be en calculated by applying a factor to the VOC emissions to calculate total organic gases (TOG)

. These TOG emissions are then split during emissions processing into “model species” that include methane

. With the low reactivity of meth ane and the absence of its use in air quality modeling for ozone, the VOC

- to

- TOG factors and the methane part of the speciation factors were not given much scrutiny

. Previous versions of this guidance encouraged inventory developers to simply use the defau lt VOC

- to

- TOG factors that were associated with the speciation profiles without further analysis, since the methane emissions were not used

. This approach may still be appropriate for most or all NAAs for their modeled attainment demonstration.

In limited situations, air agencies may want to inv estigate the extent that methane emissions pl ay a role in ozone episodes . Hence , additional efforts go ing beyond the us e of the default VOC

- to

- TOG profiles and default methane fractions from the speciation profiles m ay develop over time

. In this case, i t may be of interest to include methane emissions inputs to air quality models to achieve sufficient model performance for a modeled attainment demonstration

. Approaches can include incorporating methane emissions from other sources into emissions inventories used for modeled air quality

. For example, the MOVES model estimates methane emissions directly, so there would be no need to use VOC speciation to estimate those emissions. Air agencies considering methane as a con tributing factor should c onsult with their EPA Regional office to discuss the best sources for such data as this inventory development area is undergoing many changes at this time

. Furthermore, more specific VOC

- to

- TOG factors and speciation profiles may b e useful, particularly for analysis related to areas of very high methane emissions

. These issues are all associated with modeled attainment demonstrations, and do not affect the VOC emissions reported as part of the emissions inventory SIP.


### 4.3 Identification of Priority Sources
T he Ozone Implementation Rule and PM 2.5 SIP Requirements Rule refer to the AERR requirement s for creating th e inventories used for SIP s

. This includes the AERR requirement that inventories must include all sources of emissions

. Thus , i nventories used for SIPs are expected to be complete, with emissions from all sources characterized in some way. In addition , to better understood routine emissions sources, emissions from known or quantifiable fugitive sources such as leaking tanks or val ves should be included in inventories when these emissions can be quantified in both the base and future years and because their reductions could help in achieving att ainment. These emissions should not be excluded based on an invalid assumption that they are “malfunctions

. ” In addition, startup/shutdown emissions should be included in inventories (see Secti on 4.8.1 )

. While completeness is required, t here is no requirement that all parts of an emissions inventory be completed wi th the same degree of rigor

. Because emissions inventory development is time consuming and expensive , it is wise for inventory developers first to focus their resources on the sources of emissions making up the bulk of the pollutants relevant for the NAAQS in question

. To the extent that anEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

67 inventory is to be used for multiple NAAQS or for multi

- pollutant analysis, then the larger sources important for all relevant pollutants should be characterized with as much technical rigor as is feasible.
Fortunately, existing inventories can help states guide their initial understanding of the sources of pollutants in a particular area

. Air agencies can rely on the latest NEI or previously compiled SIP inventories to guide further development

. The NEI is commonly used as a starting point for state and regional planning purposes for NAAQS implementation and regional haze planning. The EIS can help by providing emissions summaries for counties or groups of counties and for emissions sectors or SCCs.

For additional informa tion, the Particulate Emissions volume of the EIIP technical report (see https://www.epa.gov/air

- emissions

- inventories/volume

- 9

- particulate

- emissions ) provides tho rough recommendations for identifying sources of PM emissions

. These recommendations can be useful for other pollutants as well.
Starting with an existing inventory poses some risks and challenges

. Here we try to address the most common issues associated w ith SIP inventories when starting with existing inventories:

1. How do I know which sources in an existing inventory should get further review ? The EPA suggests the following considerations in deciding which sources to be reviewed:

a. The largest contributors to the pollutants of interest (i.e., the pollutants contributing to ozone and/or PM 2.5 formation) using some coarse groupings, such as the EIS S ectors, Tier 2, or Tier 3 groups

. b. Sources within the NAA (or contributing to it in the case of modeling attainmen t demonstration inventories) . Special considerations to sources closest to and upwind of violating monitors may deserve special attention.

c. Knowledge about the growth or retraction of a particular sector of the economy. Oil and gas production is a recent ex ample of a quickly growing industrial source of emissions. d. Considering whether the proportion of emissions associated with a particular source is likely to have an impact on the outcome of decisions

. Emissions methods/changes for sectors that are likely to have a large impact on the planning process should get higher priority.

e. Assessing whether the approaches used in the preparation of SIP emissions are updated with current approaches, including appropriate emission factors. This is particularly important f or source categories for which there is large uncertainty and those with ongoing research.

2. What if the original inventory does not use good approaches? The EPA recommends starting with inventories that have available and clear documentation

. If an invento ry developer cannot figure out how the emissions were estimated, t hen it will be difficult to build upon those results

.
With documentation, inventory developers should be able to evaluate the quality of approaches used

. As part of the NEI program, the EPA publishes updated methods for many nonpointEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

68 emissions categories

. The highest quality p oint source emission s estimates are based on facility

specific testing, and where not available, current emission factors

. Mobile emissions should be ba sed on the lates t mobile models, using as many location

- specific inputs as possible.

If it is determined that a starting inventory does not use the latest methods, it is advisable to reassess those emissions with newer methods (or other available inventories) prior to de ciding if that category requires even further work.

3. If I need to make updates, w here are the latest approaches available? The EPA’s NEI program is a good source of the latest approaches and approaches in development

. In many cases, m ulti

- jurisdictional or ganizations also have updated approaches for various emissions sectors

. The Emissions Inventory Improvement Program volumes still have a lot of valuable information on emissions, though some sections are outdated (see https://www.epa.gov/air

- emissions

- inventories/emission

- inventory

- improvement

- program
eiip )

. Approaches have historically included AP

- 42 and WebFire emission factors, though these

resources are out date d for some sectors

. For more information on updated emission factors, see Section 4.6

.

4. What do I do if the NEI approach has added PM or other emissions that I did not report, and I think that they are invalid? The EPA commonly augments PM emissions provided by states in the NEI because many states do not report total PM 2.5 and neglect the condensable portion of PM emissions (see also Section 4.2.1 )

. Consistent with the requirements for c omplete SIP inventories, the EPA works to create a complete and accurate NEI

. If emissions have been added erroneously, states should make those improvements, but should also let the NEI program staff know that there may be a flaw in their methods and prov ide a better source of information

. Just because a source has not reported condensable emissions does not mean that they do not exist or should not have been characterized

. In some cases, states may need to go back to sources to clarify that condensable PM emissions must be provide d to the state agencies.

Another source for added EPA criteria pollutant and precursor emissions is NH 3 for point sources from the TRI

. Since these are emissions that the facility submits to the EPA through the TRI program, they should potentially be considered as a source of information when identifying sources of NH 3 .
Only the facility total emissions are available from the TRI program (with stack and fugitive emissions denoted separately). This is not generally enough detail f or a SIP inventory

. For SIP inventories for PM 2.5 , air agencies would need to follow up to develop more refined information about the facility NH 3 so that NH 3 emissions could be included in the SIP inventories

. If the source is a “point source” based on th e AERR thresholds for other pollutants, then including NH 3 emissions as part of the point source emissions is required by the AERR and , therefore , in PM 2.5 SIP inventories in accordance with the PM 2.5 SIP Requirements Rule

. If the source is not a pointEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

69 sou rce based on thresholds of other pollutants, than the AERR NH 3 threshold of 100 tpy potential to emit would apply in determining if the facility should be reported as a point source. Otherwise, the emissions should be included as a nonpoint source in the S IP inventory

. If a state air agency believes that these emissions are erroneous or unimportant, some discussion of these sources should be included in their SIP as to why the NH 3 emissions as identified by TRI are not being included in a SIP inventory in s ome form

. For incorrect TRI emissions, states should consider coordinating with the facility and the EPA’s TRI program to improve the emission estimates.



### 4.4 Spatial Extent The spatial extent of an inventory refers to counties, states, or other geographic regi ons c overed by the emissions data

. As described in previous s ections, inventories needing to be included in SIPs are either for the NAA area only (for ozone and PM 2.5 ) or are for the entire state (for regional haze and ozone or PM 2.5 when modeled attainmen t demonstrations are needed). Modeled attainment demonstrations are likely to use emissions from a regional multi

- state area. While i t is not a SIP requirement to submit an inventory for other states, the emissions are needed to do the modeling.

A number o f complicating issues related to spatial extent arise with inventories

. Below, more information is provided on partial counties, when point

- source locations are needed for emissions that have traditionally been nonpoint sources, shapefile

- based inventories , and link

- based mobile emissions.

4.4.1 Nonattainment A reas with Partial Counties In some cases, NAAs do not follow county boundaries

. Since most inventories and many underlying datasets are available at the county level, this poses a challenge for emissions ca lculations, in particular for nonroad and mobile sources.

A ir agencies may wish to use full

- county emissions in meeting some SIP requirements, despite the designation of partial

- county NAAs. The EPA has considered the advisability of using whole

- county emi ssions to represent partial county emissions and has determined that this is not possible. In particular, using whole

- county emissions would po se a challenge for using these inventories for ROP/RFP analyses , which can only include reductions within the NAA

. Thus, areas designated as partial counties should estimate those partial county emissions using one of the approaches described here.
For point sources, Geographic Information System ( GIS ) technology enables straightforward select ion of point sources int o a partial

- county NAA by intersecting a dataset of point source latitude/longitude coordinates with a shapefile of the NAA boundaries.
For nonpoint and mobile sources, available inventories and methods are often designed to create county totals, making pa rtial counties much more difficult

. A variety of acceptable approaches exist for calcula ting partial county emissions, though the particular approaches chosen should be agreed to as part of developing the plan for the SIP planning inventory as described in Section 2.2

.
1. Custom calculations : Air agencies could develop a custom approach to estimate emissions using activity data estimated for the partial county area

. Since many source categories need to beEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

70 estimated, this could be a very labor intensive approach, or could be used for just key categories where other approaches are insufficient.

2. Shapefile

- based inventories : See Section 4.4.3

.
3. Use of spatial allocation surrogates : Some sources of data exist at sub

- county resolution, including road networks, travel demand model results (see also Section 4.4.4 ) , and census data that are available at census tracts or blocks

. When the emis sions activity can be reasonably assumed to fo llow an allocation method based on one such surrogate dataset, GIS techniques can be followed to apportion a county emissions estimate to a partial county NAA based on the patterns of these sub

- county data.

4. Use of gridded modeling data : Modeled attainment demonstrations rely on air quality modeling that uses gridded emissions data, which could be resolved at a sub

- county resolution

. Gridding resolutions of 12

- km, 4

- km, or even 1

- km have been used

. Similar to what was described ab ove in the previous approach , emissions processing relies on spatial surrogates to apportion county

level data to grid cells needed for modeling

. Rather than take a custom spatial surrogate approach, these gridded data may be sufficient to apportion county

- level data to a partial

cou nty N AA using GIS overlay techniques

. Such an approach would sum the parts of the gridded data intersecting the partial county area to provide the partial county area inventory

. The primary difference in this approach compared to the previous approach is t he intermediat e step of using the gridded data

. This co uld be appealing since those gridded data may already be available from modeling done for attainment demonstrations

.
5. Expert judgment : When there is no appropriate sub

- county data surrogate available, w hen air quality modeling is not part of the SIP process, or when a category is relatively unimportant to the SIP planning process, other methods may be advisable

. In this case, an air agency should explain their rationale to the respective EPA Regional off ice and come to agreement on a technically reasonable approach

. Such approaches could include using the entire county estimated emissions, assuming some fraction based on understanding of county activities, or taking a n area
- proportional (uniform distribut ion) approach

. In this latter approach, the partial county emissions are assumed to be the total county emissions times the area of the partial county divided by the area of the total county.

Since these partial county emissions calculations could need to be done for a variety of inventories and for SIP revisions, considerations should be made for the repeatability of the approach so that it does not become overwhelming to the analysis

. In collaboration with the EPA Regional office , a balance needs to be fo und among level of effort, technical credibility, and repeatability.
The latest spatial approaches and data are available with the latest emissions modeling platform data on the Emissions Modeling C learinghouse ( EMCH )

. The EIIP Volume III, Chapter 1 , Section 4.3 provides

some additional information on spatial allocation ; h owever, the examples used for spatial allocation approaches are much too old for most applications , and more sophisticated spatia l surrogateEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

71 approaches are available than those given as examples

. In particular, except in rare circumstances, the use of population data as an allocation method is outdated and not recommended

.
4.4.2 Point Source L ocations Needed for Modeling of T raditional N onpoint S ources In some cases, the details needed in a modeled attainment demonstration push inventory developers to use point

- source locations for source categories that have traditionally been nonpoint sources

. Some examples include sources of agricultur al ammonia, dry cleaners, and gas stations

. Rather than creating a much larger point source inventory, one approach is to keep a source as nonpoint, but use an emissions processing technique for modeling known as area

- to

- point allocation.
While this topic is primarily one for consideration in modeling inventories, it is include d here because the planning inventory often provides a starting point for the modeling inventory (for the NAA counties). To the extent that modeling needs can drive additional detail in the planning inventories, this area

- to

point feature can allow small sources to be included as nonpoint sources in a planning inventory but still allow point source locations to be used for modeling.

In area

- to

- point allocation, the emissions processor for modeling starts with county

- wide estimates and

a user
- provided dataset that allocates county wide emissions to discrete latitude/longitude points (within the county)

. The inventory developer still must obtain the point source locations and proportion of countywide emissions, but the point source inventory remains more focused on the largest sources

. Using an area

- to

- point allocation approach also avoids having to define stack parameters for inclusion of small sources in the point source inventory, whic h is useful because the stack parameters are not necessarily relevant to or available for these source categories.

4.4.3 Shapefile

- based I nventories The EPA collects inventories for the NEI for commercial marine and locomotives using GIS shapefile

based inventor ies

. Rather than including emissions as a county total, the emissions are allocated to individual sub

- county areas or lines, each with its own GIS polygon shape

. This approach was developed primarily to support fine scale and risk modeling that are done at a scale finer than most mode led attainment demonstrations.

T hese inventories can be useful for computing partial county emissions for those categories using this approach

. Otherwise, it is not expected that states would need to start with the shapefile

- ba sed inventories for SIP planning

. In some cases, states may wish to use such inventories in circumstances where the CMV and locomotive emissions spatial distribution is critical to the modeled attainment demonstration in some way

. This may be important in NAAs that contain large ports and/or are near major coastal or inland waterways

. Even in this case, use of county total inventories with appropriate spatial allocation using other techniques will still be able to allocate emissions sufficiently for both

no nattainment area inventories (if partial counties are needed) and for modeled attainment demonstrations.

4.4.4 Link

- based On

- road Mobile E missions and Travel Demand M odels SIP planning and modeling inventories often put great focus on mobile sources through the use of detailed emissions by roadway segments (or links) and the use of travel demand models (TDMs)

. ThisEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

72 possibility is simply mentioned here for completeness and is not necessarily recommended, since thes e efforts are often substantial. The approach can also help with partial county emissions estimates

. 

### 4.5 Temporal Basis Various temporal bases may be needed for meeting different inventory requirements for SIPs. These can be different for ozone, PM 2.5 , and regional haze

. The emissions that should be used in planning inventories for ozone SIPs are ozone season day emissions

. The emissions that should be used in planning inventories for PM 2.5 SIPs are annual emissions for SIPs addressing the annual or 24

- hour PM 2.5 NAAQS or seasonal emissions for SIPs addressi ng the 24

- hour PM 2.5 NAAQS

. At a state’s option, an inventory may contain both annual and average season data emissions for SIPs addressing the 24

- hour PM 2.5 NAAQS. The temporal basis for emissions in Regional Haze SIP s is always annual actual emissions.

4.5.1 T emporal Considerations for Ozone SIPs For ozone SIPs, ozone season day emissions (as defined in Section 2.5.2 ) are used for the base year inventory for the NAA

. Since other planning inventories must be consistent with the base year inventory, inventories such as the projected attainment year inventory for the NAA and the periodic inventories must also include ozone season day emissions

. Additionally, for states that includ e modeled attainment demonstrations in their SIP, statewi de (or modeling domain

- wide) ozone season day emissions and statewide annual emissions may also be important for Regional office evaluation and approval of the modeled attainment demonstration.

Ozone season day emissions are defined in Section 2.5.2

. As explained in the definition, states must select the representative months and work week days to include in the calculation of the ozone season day emissions

. The temporal basis for these emissions should be representative of the conditions leading to nonattainment, as recommended by the state and approved by the EPA prior to finalizing the emissions approach to be used

. The EPA acknowledges that there could be instances where ozone values are elevated above the level of the NAAQS only in non

- summer months or on weekend days, including whe n winter emissions or weekend emissions dominate the episode

. In recognition of this situation , the terminology used has changed from “ summer day emissions ” to “ ozone season emissions. ” The general expectation of high emissions activity on weekdays is the basis for the weekday specification in the definition of ozone season day emissions

. However, in the event that weekend emissions were to be higher than weekday emissions, the state should consider whether weekday emissions are sufficiently representative of the nonattainment problem

. Since the goal of the definition of ozone season day emissions is representativeness of the emissions contributing to the ozone nonattainment problem, if including the weekend emissions resulted in a better representation of emissions , then states may be able to justify including weekend emissions in coordination with the EPA Regional office

. In general , t o calculate ozone season day emissions, reporting agencies should estimate emissions for a specific period (month, week, selected days, or a day) where emissions (and other factors) resulted in

ozone values above the level of the NAAQS leading to nonattainment

. The preference should be given for weekdays as previously d escribed, unless there is a reason to use other days

. A n ozone season dayEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

73 emissions value should be calculated by summing the emissions on those days and divid ing by the number of days included in the sum

. For mobile source emissions, m obile source emissi ons models can produce output for an average weekday or weekend day. Consult the EPA ’s MOVES Technical Guidance , “ MOVES2014 and 2014a Technical Guidance: Using MOVES to Prepare Emission Inventories for State Implementation Plans and transportation Conformi ty , ” for details ( https://www3.epa.gov/otaq/models/moves/ )

. This guidance provides numerous recommendations including how to determine temperatures to use in calculating emissions for base year and at tainment year NAA inventories.
As noted in the preamble for the Ozone Implementation Rule, HEDD periods could have higher emissions than during other periods , which could contribute to ozone formation in a particular nonattainment area

. Additional contribu ting factors to HEDD

- period impacts include location and timing of the HEDD

- related emissions, emissions amounts from other sources during the HEDD period, and meteorology. If an air agency determines that emissions increases ( within a NAA ) associated with HEDD periods significant ly contribute to ozone nonattainment, then the air agency should include those higher emissions in the planning inventories : the base year inventory for the NAA (which also serves as the ROP/RFP baseline) , and the attainment projec ted inventory for the NAA

. As described above, in consultation with the EPA Regional office , air agencies should select periods to use for defining the appropriate days to include in the calculation of ozone season day emissions that are representative of the conditions leading to nonattainment. Thus, air agencies that have determined HEDD periods are important should select such periods as part of their ozone season day emissions estimation approach. As a result, air agencies could estimate HEDD emissions in a way that represents an appropriate portion of their NAA emissions inventories. More information on how to estimate HEDD

- related emissions is provided in Section 4.8.1

. 4.5.2 Temporal Considerations for PM 2.5 SIPs The emissions m ust be reported as annual total emissions, average

- season
- day emissions, or both, as appropriate for the relevant PM2.5 NAAQS. The rationale for the type(s) of emissions provided must be included as part of the attainment plan. When seasonal emissions are included, the rationale for the seasonal period must also be included as part of the attainment plan. A discussion of the EPA’s rationale for including the option of seasonal or annual inventories is provided in Section IV.B.2.d of the PM 2.5 Implementation Rule preamble. The regulatory text for this requirement is also provided at 40 CFR 51.1008(a)(1)(iii).

In the case of the 24

- hour NAAQS, the form of the NAAQS is based upon monitored values on particular days with high levels of ambient PM 2.5 , and in som e nonattainment areas , those days may occur only during a distinct and definable season of the year. For the PM 2.5 NAAQS, states can meet the inventory requirement with different combinations of temporal resolutions for the emissions. For the annual standa rd, annual emissions must be submitted. For the 24

- hour standard, states must submit either an annual or an average

- season
- day inventory and optionally may submit both. For a nonattainment area for both the annual and 24

- hour standard, states can meet the inventory requirement with only an annual inventory or with both an annual and average

- season
- day inventory.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

74 In contrast with the annual PM 2.5 NAAQS, the 24

- hour PM 2.5 NAAQS is designed to protect against peak exposures. Thus, for the 24

- hour PM 2.5 NAAQS, there are circumstances in which the EPA believes that a seasonal emissions inventor y alone may be sufficient for attainment planning purposes. 40 CFR 51.1008(a)(1)(iii) allows states to use seasonal inventories for attainment plan development for attaini ng the 24

- hour PM 2.5 standard in areas that are designated nonattainment for only the 24

- hour standard. Use of a seasonal emissions inventory will also be appropriate only if the monitored violations of the 24

- hour PM 2.5 NAAQS in the area occur during an i dentifiable season. In the event that it is appropriate to rely solely on a seasonal emissions inventory, the state should confer with the EPA concerning the exact length of the season and the start and stop dates of the season. The duration and start and stop dates of the season will be an important component of the attainment plan and must be approved by the EPA along with other elements of the attainment plan for a given nonattainment area. Further, seasonal inventories must use average

- season
- day emissi ons values for this purpose, as defined by 40 CFR 51.1000. The nature of some seasonal PM 2.5 emissions sources (e.g., residential wood combustion) does not allow for only weekday emissions to be included in the inventory ; therefore , all days must be includ ed. The state would need to explain the rationale for the duration of the season used for the inventory as part of the attainment plan submission. To justify the use of a seasonal emissions inventory, the state must demonstrate why a seasonal emissions inv entory is appropriate for the particular PM 2.5 nonattainment area in question.


### 4.6 Emission Factors for SIP Emissions Inventories As expressed in 40 CFR 51.114(a), inventories “must be based on measured emissions or, where measured emissions are not available , documented emission factors

. ” Given that the preference is measured data, the intent of the regulations is for emissions to be specific to the source of the emissions

. To ensure that emissions estimates that use factors are high quality, the e mission fac tors for SIP development should come from credible source s. T he possible sources necessarily differ for stationary, on

- road mobile, and nonroad sources

. The mobile sources with EPA models are the most straightforward . For all states but California , on
- road mobile emissions should be estimated with the latest EPA on

- road model, MOVES. For California, the most recent EPA

- approved version of EMFAC should be used. For stationary sources and remaining nonroad mobile categories , there are several approaches that can be acceptable, with the guiding principle of using credible sources of data

. Where emissions inventory SIPs are to be approved by the EPA , inventory developers should work with the appropriate EPA Regional office to make sure the emission factors are a cceptable

.
Air agencies should pay close attention to the methods that they are using to calculate emissions to ensure updated approaches are used

. It would be difficult for an EPA Regional office to approve an inventory that used an outdated method for a n important part of the inventory if an updated method was available at the start of the SIP planning inventory development effort

. Since the EPA could have multiple approaches posted for the same sector and some of those approaches could be outd ated, air agencies should not assume that all EPA

- posted methods are equivalent and acceptable

. For example, some emission factors from AP

- 42 for nonpoint sources are outdated when compared to nonpoint methods and factors used for the NEI. The EPA recommends that ai r agencies refer to the latest NEIEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

75 development web pages and contact Regional office s to confirm that their planned approaches are up to date

. The IPP process described above can be helpful in this process.
For most stationary point sources, air agencies h ave rules in place that require the submission of point source data to the state for air planning purposes

. Much of these data are then submitted to the EPA as part of the NEI and used as the basis for point source inventories in SIPs

. These state rules ma y have their own requirements about emission factors and source tests to be used; where possible, these rules should follow this guidance.

The EPA recommends selecting emission factors based on the hierarchy of emission factor sources shown in Table 16 , which is c onsistent with the requirement in 40 CFR 51.114(a) that emission inventories for SIPs use measured data or emissions factors if measured data are not available

. T he higher up on this hierarchy the emission factor chosen , t he better the quality of the emissions estimate

. Based on the emission factor approach used, the states should also set the required “emission calculation method code” (see Section 2.5.14 ) for inclusion in their inventory data

.
Table 16 : Hierarchy of emission factors for use in point source emissions inventories

Rank Emission Factor Approach E mission factor method code to use 1 Continuous emissions monitoring system 1

2 Facility/process

- specific emiss ion factor

. Average of representative stack tests (on one stack) downstream of controls (or if no controls)

. 4

3 Single representative facility/process

- specific stack test downstream of controls (or if no controls)

. 4

4 Facility/process

- specific uncontro lled emission factor, plus control efficiency

. Average of representative stack tests (on one stack) upstream of controls, adjusted based on expected control efficiency. 24

5 Single representative facility/process

- specific stack test upstream of controls, adjusted based on expected control efficiency

. 24

6 Site

- specific emission factor

. Average of representative stack tests across multiple stacks or processes, downstream of controls (or if no controls)

. 10

7 Site

- specific uncontrolled emission factor, plu s control efficiency

. Average of representative stack tests across multiple stacks or processes, upstream of controls, adjusted based on expected control efficiency

. Only makes sense when all processes measured are fed to the same type/combination of contr ol devices. 30

8 Material balance 3 9 Manufacturer specification 7

10 Best available other emission factor for uncontrolled or including controls, which is one of: EPA emission factor 8 S/L/T emission factor 9Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

76 Rank Emission Factor Approach E mission factor method code to use Vendor emission factor 11 Trade gr oup emission factor 12 Other emission factor 13

11 Best available pre

- control emission factor, plus control efficiency , which is one of: EPA emission factor, plus control efficiency 28 S/L/T emission factor, plus control efficiency 29 Vendor emi ssion factor, plus control efficiency 31 Trade group emission factor, plus control efficiency 32 Other emission factor, plus control efficiency 33 1 2 Engineering judgement 2

13 Emission factor with best available speciation profile, one of:

EPA sp eciation profile 5 S/L/T speciation profile

– e.g., to calculate metals emissions from filterable PM 2.5 or volatile HAP from VOC. 6



### 4.7 Inventory Data Codes Building inventories includes the use of various codes , such as SCCs, state/county FIPS, tribal , con trol measure, NAICS , pollutant and emission method codes

. A full accounting of all possible codes is available as part of the EIS “Reporting Code Tables” available to EIS users using the “Reporting Code Tables” link at the left

- hand side . The codes are als o available to non

- EIS users (on a somewhat more delayed timetable) at https://www.epa.gov/air

- emissions

- inventories/emission

- inventory

- system

- eis

gateway u nder the “EIS Code Tables (Including SCCs) ” link. There are more than 60 separate lists of codes that define all of the required and optional coded data el ements based on the AERR

. As we have noted above, the AERR is relevant as the rule that codifies the correct development of all inventories submitted to the EPA

.
4.7.1 Codes to U se for Nonattainment Area I nventories Air agencies developing inventories for SIP planning should use valid EIS codes in all of their inventories

. Since codes change over time, the EPA has adopted the approach in the EIS to “reti re” codes when no longer needed and to add codes when needed

. Codes are generally retired in coordination with NEI development cycles, ideally retiring codes only when plenty of notice has been provided to states in advance of an NEI inventory submission period

. As such, codes that are retired may have already been used as part of a SIP development process, and that is okay. This is the advantage to retiring codes rather than removing them

. Conversely, the EPA may not be able to retire a code until an appropriate point in the triennial NEI cycle

. If an air agency wishes to submit a SIP

- related inventory to the EIS for the NEI or another purpose, it will need to use valid (and not retired) codes for the year being s ubmitted.

4.7.2 How to R equest New Codes or Code R etirements In general, if a new code is needed for compiling an inventory, then a n air agency staff member should
contact the EPA to request a new code

. The recommended contact method is to use the call or email using the contact information listed for “Facility Inventory and Point Emissions” on the EIS contacts pageEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

77 at https://www.epa.gov/air

- emissions

- inventories

. Requests for codes should include which code table(s) are affected, why existing code s are not sufficient, and a recommendation for a code and its definition and purpose

. While the EPA anticipates that code retirement requests will usually come from the EPA rather than from external groups, a code retirement request should be made using th e same mechanisms.

The EPA most often gets requests for new SCC codes since new emissions processes arise in industries, or processes are newly identified as having emissions associated with them

. If an air agency inventory developer cannot find an appropr iate SCC c ode for an inventory process, a choice needs to be made to either use a generic (“miscellaneous”) SCC or to request a new SCC

. For cases in which the contribution of the emissions process to any one precursor pollutant is minimal, inventory devel opers may choose to report using one of the miscellaneous SCCs

. If the process is a significant source of one or more pollutants or that process might be a part of a control program, then an SCC request is probably warranted . The EPA staff will evaluate th e SCC request to make sure that a similar code does not already exist, consider codes that have been created but not yet activated for use in submitted inventories 19
, assess the need for the SCC, and either indicate an existing appropriate SCC to use or ass ign a new appropriate code.



### 4.8 Estimation of Base Year Emissions This section describes the estimation of base year emissions for use in planning inventories for ozone, PM 2.5 and regional haze implementation

. S ubsections cover point, nonpoint, on
- road mobile, nonroad mobile, biogenic sources, and fires, respectively.

4.8.1 Stationary Point Stationary point sources can be estimated through continuous measurements and through more traditional methods

. EIIP Volume II, Chapter 1 , Sections 1 through 7 provide still

- relevant information on compilation and calculation of point source inventories

. Readers developing point source inventories should also use that report as a resource.

Sources estimated with CEMS
The best estimate of stationary point source emissions is obtained through the use of CEMS

. Several pollutants, including NO X , SO 2 , CO 2 , and mercury ( Hg ) can be measured with CEMS

. F uel heat input on an hourly basis is usually also be collected as part of the EPA’s CEMS programs, and heat content can be used to estimate emissions for other pollutants using emission factors (with specific test

- based factors preferred)

. More information and guidance on CEMS can be found at and http://www.epa.gov/airmarkets/emissions/continuous

- factsheet.html

. The vast majority of CEMS

- equipped sources use these measurements as part of reporting programs to the EPA

. In partic ular, the Acid Rain Program and NO X SIP call and other trading programs collect data as

19 Some SCCs are set up for use in collecting source test data and developing emission factors. Sometime after that, the SCCs can be used for creating and submitting inventories, depending on the availability of emission factors and/or the interest for using those SCCs by industry and air agencies.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

78 part of the EPA’s Clean Air Markets . Through that program, CEMS

- based emissions are available through the “Data and Maps” resource, including emissions summaries and files ready to be used in the SMOKE system used for emissions modeling

. For a few sources, emissions must be report ed only for part of the year

. In these cases, users of the data should be careful not to overrid e the annual emissions estimates for such units with the partial

- year data included in the CEMS databases

. This can be a particular challenge for modeling inventories, where the more temporal resolution is useful for the time periods covered, but the other time periods must use a different approach to apportion the remaining emissions to the rest of the year.
Other (non

- CEMS ) sources
EIIP Volume II, Chapter 1 , Section 4 pro vides general emission estimation procedure information

. It provides a table similar to Table 16 , but also focuses on the cost associated with the different approaches

. It acknowledges that the cost incurred with collecting the mo re specific source test data should be commensurate with the need for a higher data quality

. Like the EIIP figure, Table 16 also lists the more costly (and better) approaches higher on the list

. The EIIP volume provides guidance o n each of the various methods of computing emissions.

The remainder of EIIP Volume II includes chapters that address various combustion, manufacturing, and production activities that are point sources

. Information in these chapters can be used to estimate
ozone, PM 2.5 , and regional haze precursor emissions where they address the source categories of interest

. In some cases, the EIIP chapters are somewhat dated and so may not cover newer emissions processes

. In these cases, inventory developers should adapt the techniques or develop new techniques to ensure there estimates are relevant to t he sources

. The EIIP point source chapters within Volume II cover topics as follows (numbers correspond to chapter numbers) :

2. Boilers 3. Hot mix asphalt plants 4. Fugitive emissio ns from equipment leaks 5. Wastewater collection and treatment 6. Semiconductor manufacturing 7. Surface coating operations 8. Paint and ink manufacturing 9. Secondary metal production 10. Oil and gas production 11. Plastic products manufacturing 12. Effects of control device effici encies and malfunctions 13. Stone mining and quarrying 14. Uncontrolled emission factors for criteria pollutants 15. Packaging and graphic arts 16. Chemical manufacturingEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

79 Each industry

- or source
- specific document contains a brief description; identification of emission
p oints; an overview of methods available for estimating emissions; example calculations for each technique presented; a brief discussion on quality assurance ( QA ) and quality control ( 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
contro l device fuel (if applicable).

For NH 3 sources, a report is also available in the “nonpoint” section of EIIP entitled “ Estimating Ammonia Emissions f rom Anthropogenic Nonagricultural Sources

- Draft Final Report ” ( April 2004 ) and covers many point source processes as well as nonpoint ones. Although a lot of research has been done on possible new approache s to agricultural NH 3 estimation as point sources , these “farm

- based” approach es have not been completed yet. At this time, the EPA augments agricultural NH 3 sources only as nonpoint sources, rather than as point sources

. Readers should see Section 4.8.2 for more information on emissions estimation from nonpoint sources.
A final resource is to use the facility

- total NH 3 from the TRI

. For SIP planning inventory purposes, these emissions should be apportioned to individual process es, but at least can be a starting point in the absence of other information

. TRI provides emissions by stack and fugitive, with all stack emissions summed together and all fugitive emissions together

. This level of detail would not be sufficient for a sig nificant NH 3 source and so , while TRI can be a starting point, additional information would need to be gathered from the facility to apportion the emissions to the processes at the facility.
Startup / s hutdown e missions
The regulatory expectations for SSM em issions are included as part of 40 CFR p art 52 in the EPA’s “State Implementation Plans: Response to Petition for Rulemaking; Restatement and Update of EPA’s SSM Policy Applicable to SIPs; Findings of Substantial Inadequacy; and SIP Calls to Amend Provisio ns Applying Excess Emissions During Periods of Startup, Shutdown, and Malfunction ” final rule (SSM rule)

. A fact sheet and list of affected states is available on the website for this action as previously noted at https://www3.epa.gov/airquality/urbanair/sipstatus/emissions.html

. The requirements of the Ozone and PM 2.5 Implementation Rules and the Regional Haze Rule require the reporting of historical annual

- total emissions o nly (and in some areas “typical” seasonal and/or daily emissions for certain pollutants), not day

- to

- day emissions

. As noted in the preamble of the final SSM rule :

“ A ctual emissions during SSM events should be included in these annual emissions . While dat a formats are available from the EPA to allow a state to segregate the total annual emissions during SSM events from annual emissions during other type s of operation, segregat ion is not a requirement and few states do so ” (80 FR 113, page 33950).
The key t akeaway message from this guidance is that s ince startup/shutdown emissions are planned and predictable, they should be included in SIP planning inventories. While the final SSM rule generalizes that “SSM” emissions should be included, this guidance clarif ies that this means startup/s hutdownEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

80 rather than malfunction as further described below

. In addition , states should pay particular attention to estimating startup/shutdown emissions if these types of emissions are believed by the air agency to have a signi ficant contribution to the NAAQS design values.

Since malfunctions are , by nature , unpredictable and given the myriad different types of malfunctions that can occur, malfunction emissions would be difficult to estimate and future

- year malfunction events

ca nnot be readily predicted. Thus, states are not obligated to include malfunction emissions in the base inventory for the NAA, ROP/RFP plans, or attainment projected inventory for the NAA

. However, to the extent that malfunctions become a regular and predic table event, then such emissions should be quantified with regular and predictable emissions and included in emission inventories for planning purposes. The elimination of high emissions during routinely reoccurring malfunctions could potentially help achi eve significant emissions reductions needed by a state in attaining the relevant NAAQS.
For sources with CEMs that capture emission rates at all times, the CEM will capture the startup/shutdown emissions without taking any of the other steps described belo w. Without CEMs, estimating startup/shutdown emissions becomes more complicated.
Startup/shutdown emissions can be quantified by assessing the emissions during startup or shutdown periods using traditional emissions estimation approaches of throughput and emission factors. However, the throughput and emission factors must be customized for the activity during these periods. Generally, emissions rates during these periods are higher and less well characterized than a typical operating emissions rate, and so some degree of expert judgement may be needed in assessing these emissions. For example, if control devices are not effective or active during these periods, the emissions during these types would not be able to reflect controlled emissions rates

. If devic e emissions rates are associated with an operating temperature and the emissions are higher during a warm

- up period, adjustments to the emissions during the startup period could be made.
In addition to estimating the actual emissions during startup/shutdow n periods, another approach to estimate startup/shutdown emissions is to adjust control parameters via the emissions calculation parameters of rule effectiveness or primary capture efficiency. Using these parameters for startup/shutdown adjustments is not their original purpose, but can be a simple way to account for the emissions and still have a record of the routine versus startup/shutdown portions of the emissions. For example, a lower capture efficiency or rule effectiveness can adjust the estimate of emissions to be higher, accounting for extra emissions from startup/shutdown activities . In the absence of measurements of throughput and/or emissions rates during startup/shutdown periods, expert judgment may need to be used to define the adjustment facto rs to use. This approach, however, can complicate the use of the control parameters during development and documentation of control strategies since the control parameters reflect things other than controls

– thus, care should be taken when using this
appr oach.
Emissions associated with HEDD periods

As described in Section 4.5 , when air agencies have determined that emissions associated with HEDD periods are important for addressing their nonattainment problem , those air agencie s should includeEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

81 HEDD

- related emissions in their planning inventories . This subsection first describes what information is available to help assess when HEDD periods occur and to help provide activity data that could be used as part of estimat ing the assoc iated emissions. Second, this subsection describes how to consider HEDD

related emissions in planning inventories ( e.g., the base year inventory for the NAA) as compared to those in modeling inventories.
Emissions from HEDD periods can include additional e mission s from more typical EGU boilers, turbines, and other units ( collectively called peaking units) , and also from combustion

- based sources of distributed generation such as large back

- up generators and other engines. A key challenge in developing emissi ons estimates for HEDD

- periods is determining when the peaking units and distributed generation units were operating and consequently produced emissions. In the case of peaking units,
many of these sources have CEMS that record activity and emissions level s , and these data are reported to EPA . In the case of distributed generation units, little or no information may be readily available in part because the energy produced by the backup generators and other engines is not measured by the electric utilities a nd i ndependent s ystem o perators (ISO s ) , but rather may be experienced by the utilities and ISOs as a n unmeasured demand reduction.
During HEDD periods, energy customers may use backup generators to participate in demand response
programs. Though some usefu l i nformation may be available from the utilities and ISOs running those
programs, there may also be no information available . The specific r ules, reporting, and frequency of use will vary by the utility or ISO that is offering the demand response program. Demand response
p rogram requirements vary and can include : (a) c ompletely excluding the use of backup generators, (b) allowing the use of backup generators and requiring some reporting, and (c) not requiring customers to report anything about action s take n to provide the demand response. The lack of data on demand response backup activity has been noted by others based on past analyses

. 20 , 21 Where emissions from demand response programs may be important, air agencies should first collaborate with their state energy and public utility commission counterparts who may have established mechanisms for information collection and sharing. Air agencies may also need to asses s the demand response programs in their area by work ing directly with utilities and/or ISOs.

S tarting in 2015 , the National Emission Standard for Hazardous Air Pollutants (NESHAP) and New Source Performance Standards for Reciprocating Internal Combustion Engines (RICE) ( 40 CFR p art 60, Subparts IIII and JJJJ , and 40 CFR p art 63, Subpart ZZZZ ), also called the RICE rules, now r equir e owners/operators of emergency engines participating in emergency demand response programs to report the dates and times that the engines operate for emergency demand response as well as engine information such as horsepo wer and model year . While the RICE rules do not require the reporting of NO X emissions or information about non

- emergency programs, they will start to help provide information useful for

20 White paper: “ Air Quality, Electricity, and Back

- up Stationary Diesel Engines in the Northeast ,” Northeast States for Coordinated Air Use Management (NESCAUM), August 1, 2012.
21 See also the Mid

- Atlantic Distributed Resources Initiative (MADRI) working group meeting information available at http ://sites.energetics.com/madri/meetings_2012.html

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

82 understanding the activity of these back

- up generators and engines , w hich may also be helpful for ozone planning purposes

. While it may continue to be difficult to find data needed for assessing HEDD

- related emissions, air agencies may still include these emissions in both their modeling inventories and planning inventories

. The HEDD

- related emissions included by air agencies in planning inventories should have some logical relationship with the emissions in modeling inventories

. The planning inventories will of course be limited spatially to the NAA, while the modeling inve ntories will cover a larger area. Air agencies should extract the appropriate NAAs to include in the planning inventories. Temporally, t he modeling inventories will include day

- and hour

- specific emissions for seasonal or episodic periods , which can includ e HEDD period s , while the planning inventories will be a n ozone season day emissions value. As explained in Section 4.5 , the days used to calculate the ozone season day emissions are chosen for the particular SIP in consultatio n with the Regional office . Some examples of possible relationships between the modeling inventories (episode

- specific) and the planning inventories ( ozone season day) are as follows:

 Ozone season day emissions could be an average across all days of the ep isode

- specific

emissions used in the modeled attainment demonstration

.

 Ozone season day emissions could be an average of a longer episode or series of episodes that overlap with the episodic period used for the modeled attainment demonstration.

 Ozone seaso n day emissions could be a representative selection of the episodic

- specific emissions, such as a median emissions value or using a single day emissions value that somehow is representative of other days.
These are not the only possible examples. A ny appro ach chosen to determine appropriate HED D

- related

ozone season day emissions should be developed in consultation with the Regional office and should seek to meet the overall goal for the base year inventory . Namely, the NAA inventory should be representativ e of the emissions conditions within the NAA that typically lead to nonattainment problems.

4.8.2 Stationary Nonpoint Nonpoint sources collectively represent individual sources that have not been inventoried as specific point or mobile sources

. These individual sources treated collectively as nonpoint sources are typically too small, numerous, or difficult to inventory using the methods for the other classes of sources

. Stationary nonpoint sources can be estimated through numerous different approaches

. Though s ome approaches are outdated, the EIIP Volume II I , Chapter 1 , Sections 1 through 6 provide relevant information on compilation and calculati on of nonpoint source inventories

. Also , the Volume III webpage contain s numerous supplemental reports for specific source categories

. For many categories, more updated approaches are included in the EPA tools developed for use by air agencies in developi ng inventories

. The latest tools are provided as part of the materials for the latest NEI

– either as developmental materials for an ongoing NEI effort, or as supporting materials to document a completed NEI effort.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

83 Table 17 provi des a list of emissions categories, pollutants, and available approaches documentation and/or tools

. Older versions of the tools used for the 2011 NEI are still available as part of the 2011 NEI documentation at https://www.epa.gov/air

- emissions

- inventories/2011

- national

- emissions

- inventory

nei

- documentation under the “Data and documentation” link.

Table 17 : List of nonp oint categories, pollutants, and available approaches and tools

EPA

- estimated emissions source description Possible

Overlap with Point Available Nonpoint Resources (Posted year)

Agricultural Fertilizer Application 2014_Fertilizer_Application_v1.0_22apr2016.zip (2016) Old: ag_fertilizer_application_2011 .zip (2013) Agricultural Fires 2014 Draft Agricultural Burning and Grass/Pasture Estimated Emissions (2016) Agricultural Tilling 2014_Agricultural_Tilling_v3.1_10mar2016.zip (2016)
Animal Husbandry 2014_Ag_Livestock_v1.0_20may2016.zip (2016) Old: animal_livestock_emissions_2011.zip (2009)
Architectural Coatings Solvent_Tool_v1_5.zip (2016) EIIP, Volume III , Chapter 3 (1995) Asphalt Paving Y 2014_NPt_Asphalt_18nov2015_edit03302016.zip (2016) EIIP, Volume III , Chapter 17 (2001) Aspha lt Roofing Kettles Y See abstract available with the EIIP Volume III website (2000) Autobody Refinishing Y Solvent_Tool_v1_5.zip (2016)
Aviation Gasoline 2014_Av_Gas_Stage_1_15nov2015.zip (2015) 2014_Av_Gas_Stage_2_15nov2015.zip (2015) Backyard Barbecues 2014_Backyard_BBQs_15nov2015.zip (2016 ) Commercial Cooking 2014_Commercial_Cooking_v1.2_08mar2016.zip (2016) Consumer & Commercial

– All personal care products Solvent_Tool_v1_5.zip (2016) EIIP Volume III , Chapter 5 (1996)
Consumer & Commercial

– All household produc ts Solvent_Tool_v1_5.zip (2016) EIIP Volume III , Chapter 5 (1996) Consumer & Commerci al

– All coatings and related products Solvent_Tool_v1_5.zip (2016)

Consumer & Commercial

– All adhesives and sealants Solvent_Tool_v1_5.zip (2016) EIIP Volume III , Chapter 5 (1996)
Consumer & Commercial

– All FIFRA related products Solvent_Tool_v1_5.zip (2016)

Degreasing Y Solvent_Tool_v1_5.zip (2016) Dental Preparation and U se epa_mercury_dataset_ 62714(2).zip (2015) Documentation for the 1999 Base Year Nonpoint area source National Emissions inventory for HAPs, page A

- 30 (2000) Dry Cleaning Y Solvent_Tool_v1_5.zip (2016) EIIP, Volume III , Chapter 4 (1996) Dust

– Paved Roads 2014_Road_Dust_v2.1_09mar2016.zip (2016) Dust

– Unpaved Roads 2014_Road_Dust_v2.1_09mar2016.zip (2016) Dust

– Construction 2014_Construction_Dust_v3.0_18feb2016.zip (2016)Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

84 EPA

- estimated emissions source description Possible

Overlap with Point Available Nonpoint Resources (Posted year)

Gasoline Dist ribution/Marketing Y 2014_Gasoline_Distribution_v1.0_with_PT_subtraction_01apr2016.zip (2016) EIIP, Volume III , Chapter 11 (2001) General Laboratory Activities epa_mercury_dataset_ 62714(2).zip (2015)

Graphic Arts Y Solvent_Tool_v1_5.zip (2016) EIIP Volume III , Chapter 7 (1996) Human C remation Y cremation_2011.zip ( 2013 ) Industrial, Commercial/Institu

tional Fuel Combustion Y ICI Tool v1_4.zip (2015) Estimating Ammonia Emissions From Anthropogenic Nonagricultural Sources

- Draft Final Report (April 2004) Industrial Surface Coating Y Solvent_Tool_v1_5.zip (2016) EIIP, Volume III , Chapter 8 (1997) Lamp Breakage (La ndfill emissions) epa_mercury_dataset_ 62714(2).zip (2015) Lamp (Fluorescent) Recycling epa_mercury_dataset_ 62714(2).zip (2015)
Landfills Y EIIP, Volume III , Chapter 15 (2001) * Mining and Quarrying 2014_Mining_and_Quarrying_v2.3_09mar2016.zip (201 6 )

Oil and Gas Production Y OIL_GAS_TOOL_2014_N EI_EXPLORATION_V1_5 .zip (2016) OIL_GAS_TOOL_2014_NEI_PRODUCTION_V1_ 5_Access2007 .zip (2016) OIL_GAS_TOOL_2014_NEI_PRODUCTION_V1_ 5_Access2013 .zip (2016) Open Burning (Leaves, Brush, Residential Household Waste, Land Clearing) 2014_Open_Burning_v1.1_03mar2016.zip (2016)

Other Special Purpose Coatings Y Solvent_ Tool_v1_5.zip (2016)

Pesticide Application 2014_Agricultural_Pesticides_v2.0_18feb2016.zip (2016) EIIP Volume III , Chapter 9 (2001) Portable Gas Cans (Residential and Commercial) 2014_Portable_Fuel_Conta iners_25nov2015.zip (2016)

Publicly Owned Treatment Works Y 2014_POTW_nonpoint_emissions_23march2016.zip (2016)

Residential Heating

- Fossil F uels 2014_Residential_Heating_non

- Wood_v1.2_09mar2016.zip (2016) See also abstracts available for coal, fuel oil & kerosene, gas & liqui fied petroleum gas (LPG) available with the EIIP Volume III website (1999). Residential Heating

– Wood 2014_RWC_v3.0_28apr2016.zip (2016) EIIP, Volume III, Chapter 2 (2001) Structure Fires EIIP, Volume III, Chapter 18 (2001) Traffic Markings So lvent_Tool_v1_5.zip (2016) EIIP, Volume III , Chapter 14 (1997) Vehicle Fires See abstract available with the EIIP Volume III website (2000) Waste Disposal (Incineration) Estimating Ammonia Emissions From Anthropogenic Nonagricultural Sources

- Draft Final Report (April 2004) * Landfill emissions estimates are available in the NEI as point sources, based on the activity information submitted to the EPA as part of the Greenhouse Gas Reporting Rule.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

85 As indicated in Table 17 by the column “Possible Overlap with Point , ” some source types can have emissions in both the point source data category and the nonpoint one

. Some categories that may have both types of sources are denoted, and this list is based on what has been seen in the NEI

. The list of categories in this situation depend on an individual state’s policies, such as what the emissions size threshold is for a point source and whether any categories are treated as point sources despite having low individual emissions.
To prevent overestimation of nonpoint emissions for sectors that also have point sources, it is important to perform point/nonpoint reconcil i ation

. This reconciliation starts by subtracting the activity associated with the point sources from the total activity data ( prior to computing the nonpoint emissions )

. Since point sources often have emissions controls, it is usually not sufficient to just subtract point source emissions from total activity

- based emissions to prevent double counting. Subtracting controlled poin t source emissions from uncontrolled total activity

- based emissions would result in too much nonpoint emissions

. Rather, the point source activity must be determined and subtracted from total activity to get the nonpoint activity estimate

. Alternatively, u ncontrolled point source emissions can be calculated and subtracted from the total activity

- based emissions estimates to derive a nonpoint emissions estimate

.
Part of developing refined nonpoint emissions estimates for a SIP could involve the use of survey s to collect data

. Inventory preparers often use survey questionnaires to gather point source emissions inventory data. The EIIP Volume III, Chapter 24 , written in 2000, provides guidance on developing and conducting surveys for area source inventories

. Since this document predates some of the newer online survey techniques, the sections describing the use of the internet are outdated

. As par t of the documentation for inventories, survey design and results should be kept and included in any documentation reports or appendices.

4.8.3 On

- road Mobile Emissions from on

- road vehicles are the result of several emission processes, including the combustion of fuel while vehicles are starting, idling, and moving, evaporation of fuel from the fuel system and during refueling, and from brake wear and tire wear.
For all states but California, on

- road mobile emissions should be estimated with the latest EPA on

- r oad mobile model, MOVES

. MOVES estimates emissions for many combinations of vehicle classifications and fuel types. Readers should follow the latest MOVES guidance available at http://www3.epa.gov/otaq/ models/moves/

. For California, the most re c ent EPA

- approved version of EMFAC should be used.
The available guidance covers using MOVES for inventory development in SIPs in states other than California

. The guidance focuses on determining what the appropri ate inputs are and how MOVES should be run to develop emissions estimates for on

- road vehicles

. It describes when default MOVES inputs are appropriate for SIPs and regional conformity analysis and what factors to consider for providing locality

- specific MO VES inputs.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

86 MOVES estimates emissions for multiple source use types (the terminology that MOVES uses to describe vehicle type) and fuel types

. MOVES also estimates emissions for different road types that represent rural and urban unrestricted and restricte d (accessed only by an on or off ramp) access roads, as well as off

- network emissions such as vehicle starts, evaporative emissions while parked, and hoteling emissions when long

- haul combination trucks are parked for long periods with the engine running u nder load.
One of the key elements for use of MOVES is creating a Run Specification (RunSpec) file, which defines the place and time period of the analysis as well as the vehicle types, road types, fuel types, and the emission

- producing processes and pollu tants that will be included in the MOVES run

. The MOVES Technical G uidance describes using the MOVES graphical user interface GUI to set up a MOVES run for a particular scale (e.g., county), time period, set of pollutants, and the vehicle types, road types , and fuel types applicable to a particular area and time.
Another key element for use of MOVES is entering local meteorology, fleet, activity, fuel, and control measure information using the County Data Manager

. The MOVES Technical Guidance discusses when local data should be used in place of model default data, as well as potential sources of local data.
For some input parameters, there is overlap with the inputs needed for other models, such as the nonroad mobile models (e.g., meteorology and fuels )

. Ef forts should be made to use the same source of data across multiple categories when the inputs are shared

. Not doing so calls into question the validity of one or both approaches

. Air agencies should explain the use of shared inputs, or reasons for not usi ng them, as part of the documentation provided with their inventories.

4.8.4 Nonroad Mobile Equipment Nonroad mobile equipment emissions result from the use of fuel in a diverse collection of vehicles and equipment, including:

 recreational vehicles, such as all

- terrain vehicles and off

- road motorcycles;

 logging equipment, such as chain saws;

 agricultural equipment, such as tractors;

 construction equipment, such as graders and back hoes;

 industrial equipment, such as forklifts and sweepers;

 residential and commerc ial lawn and garden equipment, such as leaf and snow blowers;

 recreational marine vessels, such as power boats.
Starting with MOVES 2014, MOVES incorporates and expands upon the capabilities of the older NONROAD model

. States are required to use MOVES for any nonroad source emissions estimates for SIP development that is started since the release of MOVES 2014.
MOVES nonroad capabilities include predict ing emissions for all of these nonroad equipment categories listed above

. Emissions from CMVs , locomotives , and aircraft are estimated in other ways and described in Section 4.8.5

. The MOVES nonroad capabilities include more than 80 basic and 260 specific types ofEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

87 nonroad equipment and further stratifies equipment types by horsepow er rating

. Fuel types include gasoline, diesel, compressed natural gas ( C NG ) , and Liquified Petroleum Gas ( LPG )

.
The nonroad capabilities of the MOVES model estimates emissions for all criteria pollutant and precursors from both exhaust and non

- exhaust pro cesses (diurnal, refueling spillage, vapor displacement, hot soak, running loss, take permeation, hose permeation, and crankcase emissions)

. NONROAD supports many SIP

- related inventor y development needs , including support for partial counties and seasonal emissions

.
Air agencies have the option of replacing default model inputs with more representative data

. Common input adjustments include equipment population, geographic allocations, and local growth rates

. If agencies make changes to default model values , the agency should submit the input files to the EPA as well as a description of why the defaults were changed

. Additional guidance on improving n onroad estimates for lawn and garden equipment can be found in EIIP, Volume IV , Chapter 3.
For some input parameters, there is overlap with the inputs needed for other models, such as the on

road mobile models (e.g., meteorology and fuels )

. Efforts should be made to use the same source of data across multiple categories when the inputs are shared

. Not doing so calls into question the validity of one or both approaches

. Air agencies should explain the use of shared inputs, or reasons for not using them, as part of the documentatio n provided with their inventories.

4.8.5 Other Nonroad Mobile The MOVES model does not provide air agencies with a tool for estimating emissions for CMVs , aircraft, and locomotives

. Thus, separate methods are used for each of these emissions sectors.
For purpos es of reporting data to the EPA , aircraft emissions are often reported as point sources, with this being a requirement for reporting data to the EIS for use in the NEI

. Likewise, the CMV and locomotive data are included in the nonpoint data category in the EIS

. While these sources are still mobile sources from the traditional standpoint of emissions categories, for data formatting and reporting purposes in the EIS , they are treated along with these non

- mobile data categories.

4.8.5.1 Aircraft The aircraft sector in cludes all aircraft types used for public, private, and military purposes. This includes four types of aircraft: (1) c ommercial, (2) a ir t axis (AT), (3) g eneral a viation (GA), and (4) m ilitary

. A critical detail about the aircraft is whether each aircraft is turbine

- or piston

- driven, which allows the emissions estimation model to assign the fuel used, jet fuel or aviation gas, respectively

. The fraction of turbine

- and piston

- driven aircraft is either collected or assumed for all aircraft types. NEI data a re available for this sector for use as a starting point in SIPs, though the NEI includes military aircraft only where state or local air agencies have submitted military aircraft emissions data.
Commercial aircraft include those used for transporting pass engers, freight, or both

. Commercial aircraft tend to be larger aircraft powered with jet engines

. ATs carry passengers, freight, or both, but usually are smaller aircraft and operate on a more limited basis than the commercial aircraft

. GA includes mostEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

88 o ther aircraft used for recreational flying and personal transportation

. Finally, military aircraft are associated with military purposes, and they sometimes have activity at non

- military airports.
The national AT and GA fleet includes both jet

- and piston

- powered aircraft

. Most of the AT and GA fleet are made up of larger piston

- powered aircraft, though smaller business jets can also be found in these categories

. Military aircraft cover a wide range of aircraft types such as training aircraft, fighter jets, helicopters, and jet

- powered and piston

- powered planes of varying sizes.
Emissions at airports also include other sources that are a part of the nonroad equipment emissions described in Section 4.8.4

. These emissions come from aircraft auxiliary power units (APUs) and aircraft ground support equipment (GSE) typically found at airports, such as aircraft refueling vehicles, baggage handling vehicles, and equipment, aircraft towing vehicles, and passenger buses

. In the NEI point s ource inventory, these APUs and GSE are located at the airport facilities as point sources along with the aircraft exhaust emissions (though not as part of the aircraft sector). Emissions from APUs and from GSE can be calculated using the EPA ’s NONROAD mod el and by the Federal Aviation Administration (FAA) Emissions and Dispersion Modeling System (EDMS)

. If the air agency chooses to calculate these emiss ions with the EDMS, care should be taken to remove exclude those emissions from emissions associated with the NONROAD model.

The EPA collaborates with the FAA to develop and maintain methods for estimating aircraft emissions using EDMS, which also estimate s emissions from aircraft in addition to the APUs and GSE as noted above

. The emissions developed in this way are associated with aircrafts’ landing and takeoff (LTO) cycle

. The EPA encourages state and local air agencies to collect aircraft LTO activity d ata that can be used in improving estimates using the EPA EDMS

- based methods

. More details on the EPA methods are available in the documentation and methods associated with the latest NEI year found at https://www.epa.gov/air

- emissions

- inventories/national

- emissions

- inventory

.
The aircraft sector includes numerous SCCs as shown in Table 18 , and all but two of these are associated with the NE I point source inventory

. Historically, airport emissions have been calculated as a nonpoint source, but with the latest approaches having all airport locations readily available, such a simplification is no longer needed

. The result of this change from no npoint to point sources is that most of the SCCs are shown as 10

- digit SCCs (usually used just for nonpoint sources) but are now used as point SCCs

.

Table 18 : Aircraft SCCs and Data Categories in EPA Estimates
SCC Data Category SC C Description EPA estimates 2275001000 Point Mobile Sources; Aircraft; Military Aircraft; Total X
2275020000 Point Mobile Sources; Aircraft; Commercial Aircraft; Total: All Types X
2275050011 Point Mobile Sources; Aircraft; General Aviation; Piston X 2 275050012 Point Mobile Sources; Aircraft; General Aviation; Turbine X 2275060011 Point Mobile Sources; Aircraft; Air Taxi; Piston X 2275060012 Point Mobile Sources; Aircraft; Air Taxi; Turbine X
2260008005 Point Mobile Sources; Off

- highway Vehicle Gasol ine 2

- Stroke; Aircraft Ground Support Equipment XEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

89 SCC Data Category SC C Description EPA estimates
2265008005 Point Mobile Sources; Off

- highway Vehicle Gasoline 4

- Stroke; Aircraft Ground Support Equipment X

2267008005 Point Mobile Sources; LPG; Aircraft Ground Support Equipment X

2268008005 Point Mobi le Sources; CNG; Aircraft Ground Support Equipment X

2270008005 Point Mobile Sources; Off

- highway Vehicle Diesel; Aircraft Ground Support Equipment X

2275070000 Point Mobile Sources; Aircraft; Aircraft Auxiliary Power Total X
2275085000 Nonpoint Mobile Sources; Aircraft; Unpaved Airstrips; Total
2275087000 Nonpoint Mobile Sources; Aircraft; In

- flight (non

- Landing

Takeoff cycle) X

In June 2012, the EPA promulgated standards for NO X emissions from commercial aircraft engines

. Information about this rul e including fact sheets, test procedures, and emissions documentation is available on the EPA website for this purpose ( https://www3.epa.gov/otaq/aviation.htm ). In th at rule, the EPA adopted Tier 6 and Tier 8 standards for NO X on new aircraft engines, with compliance dates in 2013 and 2014

. Prior rules published in 2005 and 1997 also reduce aircraft NO X emissions with engine standards ( documented on the same website )

. When estimating emissions from airc raft, it is best practice to consider the impacts of these rules for improving the accuracy of emissions inventories

. This is why the EPA recommends using the EPA EDMS

- based approach with locality

- specific data.
State or local air agencies may determine th at the EPA default method is not appropriate for SIP purposes, though the EPA recommends considering the approach but using more locality

- specific activity information

. For areas that have provided the EPA locality

- specific airport activity data, the NEI

e stimates may very well provide emissions needed to meet SIP requirements

. The EPA method is more robust than older methods and includes national control programs as noted below

. As shown in the table above, the EPA ’s methods do not estimate emissions from unpaved airstrips (SCC 2275085000)

. Furthermore, the “in

- flight” SCC (2275087000) is covered by the EPA ’s method for only lead (Pb) emissions and is related to general aviation aircraft that still use leaded fuel

. A ir agencies may want to consider unpaved airstrips and/or in

- flight emissions for other pollutants as part of their inventories for improved model performance or other reasons, though doing so may not be necessary depending on the significance of those emissions in a particular area

. Any locality

- specific data or custom emissions associated with aircraft sources are expected to be included with supporting documentation for the emissions inventory used for a SIP.

4.8.5.2 Commercial Marine The CMV emissions category includes boats and ships used either dire ctly or indirectly in the conduct of commerce or military activity

. The majority of vessels in this category are powered by diesel engines that are either fueled with distillate or residual fuel oil blends

. For the purpose of this inventory , we assume that Category 3 (C3) vessels primarily use residual blends while Category 1 and 2 (C1 and C2) vessels typically use distillate fuels. Another consideration for emissions estimation of CMV sources isEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

90 auxiliary engines

. All three types of vessels may have auxili ary engines that are used for onboard power generation or other needs.
The C3 inventory includes vessels which use C3 engines for propulsion

. C3 engines are defined as having displacement above 30 liters per cylinder

. C3 inventories typically include emiss ions from both propulsion and auxiliary engines used on these vessels, as well as those on gas and steam turbine vessels

. Geographically, the inventories include port and interport emissions that occur within the area that ex tends 200 nautical miles (nm) f rom the official U.S. shoreline, which is roughly equivalent to the border of the U.S. Exclusive Economic Zone

. For national inventories created by the EPA , only some of these emissions are allocated to states based on official state boundaries that typica lly extend 3 nm offshore

. The EPA recommends that state water boundaries also be used when determining which emissions should be included with a particular state or county.
The C1 and C2 vessels tend to be smaller ships that operate closer to shore, and al ong inland and intercoastal waterways , with engines greater than or equal to 37kW

. Naval vessels are not included in C1 and C2 vessel inventories, though Coast Guard vessels are included

. While these C1/C2 vessels are most often associated with near

- land a pplications and thus included as within state waters, sometimes these vessels are used outside of state waters, particularly in the Gulf of Mexico

. In these cases, as with C3 vessels , the EPA recommends that state water boundaries be used when calculating emissions associated with a particular state or county.
The CMV source category does not include recreational marine vessels, which are generally less than 100 feet in length, most being less than 30 feet and powered by either inboard or outboard engines

. The calculation of these emissions is included in the NONROAD model , and these emissions are , therefore , considered “nonroad equipment

. ”

The EPA develops and maintains methods for estimating CMVs , and these methods are used as “fallback” methods for use in the NEI

. They are also available as a fallback for states without other data for this sector

. At this time, the EPA ’s methods are top

- down national methods, which apportion nationally estimated emissions values to the states and counties

. In the latest su ch approaches (used for the 2008 and 2011 NEI), this apportionment includes allocation to GIS shapefiles for ports and underway emissions

. These shapefiles are available with the latest NEI documentation and include separate files for ports and underway

. K ey differences associated with various EPA methods from the 2002 NEI through the 2011 NEI have focused on allocation of emissions to the shapefiles, which has been done in collaboration with state and local air agencies.

The current EPA methods also use em issions types

. Each of the CMV SCCs requires an appropriate emissions type (M=maneuvering, H= hoteling , C=cruise, Z=reduced speed zone) , because emission factors vary by emission type

. For the NEI, e ach SCC and emissions type combination was allocated to a shapefile identifier in the nonpoint inventory

. The allowed combinations of SCCs and emission types are shown in Table 19

. The default values are those assumed when the actual emission type may be unknown; for example, emissions t hat occur in shipping lanes are assumed to be ‘cruising’ and cannot be ‘ hoteling , ’ which only occurs at ports.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

91 Table 19 : Commercial marine SCCs and emission types in EPA emissions
SCC SCC Description Allowed Default 2280002100 Mar ine Vessels, Commercial Diesel Port M M 2280002200 Marine Vessels, Commercial Diesel Underway C C 2280003100 Marine Vessels, Commercial Residual Port H H 2280003100 Marine Vessels, Commercial Residual Port M H 2280003200 Marine Vessels, Commercial Re sidual Underway C C 2280003200 Marine Vessels, Commercial Residual Underway Z C

State or local agencies may determine that the EPA default method is not appropriate for SIP purposes
or may need further refinement by air agencies in developing SIPs

. Fo r example, the general calculation method may be a reasonable approach, but the activity and spatial allocation achieved from a top

- down approach could be improved by using the same methods with locally resolved input data to calculate emissions for specif ic areas.
When estimating CMV emissions, reporting agencies should consider national regulations that decrease emissions from this sector , such as increasingly stringent emissions requirements for n ew marine diesel engines and sulfur requirements for marin e diesel fuel and adjust their estimates accordingly

. Emissions reductions resulting from requirements for new marine engines are generally not immediately reflected in inventories as newer engines are gradually incorporated into the vessel fleet and as ol der engines/vessels are retired

. Emissions reductions resulting from the use of lower sulfur fuels are generally seen more quickly, though estimating impacts can be complicated by vessels coming from other parts of the world with different fuel standards. Table 20 provides a list of more recent relevant regulations and associated references for the CMV category

. Older Tier 1 and 2 regulations on marine diesel engines , dating back to 1999, are also listed on the websites shown in th e table

.

Table 20 : Commercial m arine v essel recent regulations and impacted pollutants

Regulation Pollutants impacted Reference
Great Lakes Steamship Repower Incentive Program (January, 2012) SO 2 , PM 2.5 www 3 .epa.gov/otaq/ oceanvessels.htm Tier 2 and Tier 3 Emissions Standards for Category 3 Marine Diesel (April

, 2010). Includes both engine standards and fuel sulfur limits. SO 2 , NO X , PM 2.5

Tier 3 and Tier 4 Emission Standar ds for Category 1 and 2 Marine Diesel Engines (June, 2008)

. PM 2.5 , NO X www 3 .epa.gov/otaq/ marine.htm#regs Nonroad Diesel Tier 4 Rule (May 2004) . Decreased allowable levels of sulfur in marine di esel fuel by 99%, taking e ffect in 2007. SO 2

For states needing to refine their emissions estimates beyond the values produced by the EPA ’s default methods, Table 21 provides a list of the latest resources for states in better understanding how to calculate emissions for the CMV sources

. The newer references are included higher in the table

. The EPA’s recent method updates have occurred in conjunction with rule development efforts, and so someEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

92 of these documents are associated w ith inventories developed for the rules listed above

. Even newer methods may become available over time and can be considered for use in SIP planning inventory development

. Much of this information is also available on the EPA nonroad mobile website under

“ O ther Nonroad Reference Material , ” available at http://www3.epa.gov/otaq/nonrdmdl.htm

. Any locality

- specific data or custom emissions associated with CMV emissions are expected to be included with supp orting documentation for the emissions inventory used for a SIP.

Table 21 : Current EPA methods for commercial marine vessel emissions. Inventory approach resource CMV Approaches For... Reference Current Methodologies in Preparing Mo bile Source Port

- Related Emissions I nventories (April, 2009) Ocean going (generally C3) vessels, harbor craft, cargo handling, https://archive.epa.gov/sectors/web /pdf/por ts

- emission

- inv

- april09.pdf

Draft Regulatory Impact Analysis: Control of Emissions of Air Pollution from Category 3 Marine Diesel Engines (June, 2009) Bottom

- up port C3 emissions for 89 deep water and 28 Great Lake ports in the U.S. and interport emissio ns from the Waterway Network Ship Traffic, Energy and Environmental Model (STEEM). https://www3.epa.gov/otaq/regs/ nonroad/marine/ci/420d09002.pdf

. See Chapter 3.

Category 2 Ve ssel Census, and Spatial Allocation Assessment and Category 1 and Category 2 in

- Port/At

Sea Splits ( EPA

- HQ

- OAR

2003

- 0190

- 0423) C1 and C2 vessels https://www.regulations.gov/doc um ent?D=EPA

- HQ

- OAR

- 2003

- 0190

- 0423

Final Regulatory Impact Analysis: Control of Emissions of Air Pollution from Locomotive Engines and Marine Compression Ignition Engines Less than 30 Liters per Cylinder (May 2008) C1 and C2 propulsion, C1 marine auxilia ry, <37kW commercial propulsion, and <37kW marine auxiliary. http://nepis.epa.gov/Exe/ZyPURL.cgi ?Dockey=P10024CN.txt

. Chapter 1 provides more in

- depth description of engine types, whil e Chapter 3 provides emissions calculation approach.

Emissions I nventory I mprovement P rogram Evaporative VOC emissions from marine transport of petroleum liquids, including the loading and unloading of the petroleum liquids. ‡ EIIP, Volume III , Chapter 12 “ Marine Vessel Loading, Ballasting, and Transit

. ”

‡ These emissions are often included in as part of the nonpoint inventory rather than a ssociated with the CMV sector. Older approaches are also available

. In 1999, the EPA sponsored two studies , “Commercial Marine Activity for Great Lake and Inland River Ports in the United States , ” and “Commercial Marine Activity for Deep Sea Ports in the U nited States.” Both of these reports are available at https://www3.epa.gov/otaq/oceanvessels.htm

. These studies provide activity profiles for approximately 150 ocean, lake, and river ports, and pr esent a method for an inventory preparer to allocate time

- in

-Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

93 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; and 3) number of hours at each time

- in

- mode associated with cruising, reduced spee d, maneuvering, and hoteling

. These methods provide alternative approaches for st ate and local air agencies in preparing SIP inventories, but care should be taken to incorporate the impact of national rules incorporated into the newer approaches as documented in Table 21

. 4.8.5.3 Locomotives The locomotive emissions category includes diesel

- electric engines, which use 2

- or 4

- stroke diesel engines and an alternator or a generator to produce the electricity required to power its traction
motors

. The EPA default approach does not include locomotives powered by electrici ty or steam

. It is believed that the number of wood or coal driven steam locomotives in the U.S. is currently very small; therefore, these types of locomotives are not generally included

. In specific instances, if such sources are relevant to a NAA , then t hey may need to be included

. The locomotive sources are further divided into categories: Class I line haul ; Class II/III line haul ; Passenger ; Commuter ; and Yard.
In the NEI, rail yard emissions are treated as point sources

. Whether rail yards should be tr eated as a point source for SIP planning purposes depends on the importance of these emissions to the NAA and the analyses that need to be done for any modelled attainment demonstration

. Emissions at these

sources can include both stationary sources (e.g., switching engines ) and mobile sources ( locomotives )

. B ecause of the mobile source component, a rail yard doesn’t necessary meet the technical definition of a major source

. Nevertheless, for NAAs where rail yards are a significant source, the EPA recommend s that states consider treating these as point sources so that the best spatial allocation can be used for modeled attainment demonstration.
Several definitions come into play in determining the locomotive category, which impacts the SCC that should be use d.

 Class I railroads are those that operate in many different states over thousands of miles of track

. They are defined by the U.S. Surface Transportation Board as having annual carrier operating revenues of $250 million or more. As of 2014, there were 8 s uch railroads in the U.S

. : Amtrak and seven freight railroads, designated Class I based on 2011 measurements released in 2013 ( "Class I Railroad Statistics"

. Association of American Railroads. April 17, 2013 .)

 Class II/III railroads are also known as short line and regional railroads, and they range in size from very small (a few carloads of freight per month) to multi

- state railroads just under Class I size

. C lass II railroads are defined as hav ing revenues greater than $20.5 million but less than $277.7 million for a least 3 consecutive years

. Switching and terminal railroads are excluded from Class II status

. A Class III railroad is defined as a rail company with annual operating revenue of less than $20 million.

 Line haul refers to higher power usage of locomotive engines during extended mileage. It is also associated with a test cycle used for estimating emission factors intended to represent emissions durin g line

- haul activity.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

94 The EPA develops and maintains methods for estimating locomotive emissions, and these methods are used in the NEI in the absence of more updated data from air agencies

. They are also available as a fallback for states without other da ta for this sector

. The EPA’s 2011 national rail estimates were developed by applying growth factors to the 2008 NEI values based on railroad freight traffic data from the 2008 and 2011 “R

- 1” reports submitted by all Class I rail lines to the Surface Trans portation Board and employment statistics from the American Short Lines and Regional Railroad Association for C lass II and III. In the latest such approaches (used for the 2008 and 2011 NEI), this apportionment includes allocation to GIS shapefiles for lin e
- haul and rail yard emissions

. The EPA project report Development of 2011 Railroad Component for National Emissions Inventory ( September 2012) provides the EPA ’s latest estima tion approach and references the 2008 approach as well

. The report for the 2008 NEI was another project report, called Documentation for Locomotive Component of the National Emissions Inventory methodology (May 2011) and available in the zip file posted wi th the 2008 NEI document at ion

. Ongoing work for the 2014 NEI and future inventories will further improve upon past methods.

The 2008 and 2011 EPA default method was developed with a consortium of the EPA, state, and industry, led by the Eastern Regional Technical Advisory Committee (ERTAC)

. The ERTAC group provided data and reviewed methods as is described in the 2008 NEI Technical Support Document and associated documentation

. Table 22 lists the locomotive SCCs used in the EPA default methodology

. Other SCCs exist as valid SCCs, but are not used in the EPA method, so states should consider this when comparing the E PA estimates to locality

- specific estimates and when merging emissions inventories that include both state/local components and the EPA estimates.

Table 22 : Locomotive SCCs

SCC Description EPA Estimated? Data Category
2285002006 Mobile Sources Railroad Equipment Diesel Line Haul

Locomotives: Class I Operations Yes

– in shape files Nonpoint

2285002007 Mobile Sources Railroad Equipment Diesel Line Haul

Locomotives: Class II / III Operations Yes

- in shape files Nonpoint

2285002008 M obile Sources Railroad Equipment Diesel Line Haul

Locomotives: Passenger Trains (Amtrak) no Nonpoint

2285002009 Mobile Sources Railroad Equipment Diesel Line Haul

Locomotives: Commuter Lines no Nonpoint
2285002010 Railroad Equipment Diesel Yard Locomoti ves no Nonpoint
28500201 Internal Combustion Engines Railroad Equipment

Diesel Yard Yes

– as point
sources Point

State or local agencies may determine that the EPA default method is not appropriate for SIP purposes or may need further refinement by air agencies in developing SIPs

. A number of ways to improve the EPA estimates were noted in the original 20 11 report (see ftp://ftp.epa.gov/EmisInventory/2011/doc/2008nei_lo comotive_report.pdf ) that documented the approach used for the 2008 NEI

. For the Class I line

- haul emissions, t he report identifies the most important considerations such as the rail link

- level freight tonnage

. Other variables were not addressedEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

95 in the me thodology, including track grade and track speed

. While the method calculated railroad

specific fleet

- averaged emission factors from industry fleet data, it is noted that emissions from individual engines are highly variable even for the regulated engine categories depending on variables such as the specific locomotive model, operation cycle, and conditions of operation

. Furthermore, the EPA approach does not address the seasonality of the emissions, while activity levels of different engines do vary seaso nally and could impact emissions for seasonal inventories

. Any locality

- specific data or custom emissions associated with locomotive sources are expected to be included with supporting documentation for the emissions inventory used for a SIP.

For the rail yard emissions, we have already noted above the consideration of rail yards as point sources. In addition, the 2011 report mentioned in the last paragraph notes additional considerations for improvements. For example, us ing the tonnage hauled as an indicat or of the amount of switching activity is an assumption that could reduce uncertainty. The variability associated with actual switching duty

- cycles and in the number of switchers operating at some rail yards seasonally was not considered in the method.

Loc omotive idling emissions is another issue that is not clearly considered in the default EPA methodology and could have an impact on emissions estimates

. During normal operations, locomotives have numerous reasons why they may remain idling including the sw itching operations noted above

. The EPA has included regulations on idle emissions to help address this source

. More details on idling emissions from locomotives is available in “ C ontrol of Emissions from Idling Locomotives ” (EPA, March 2008).
The EPA website on locomotive regulations and locomotive emissions ( https://www3.epa.gov/otaq/locomotives.htm ) provides a resource fo r understanding the regulations that apply to locomotives and how those may impact emissions

. Only one recent regulation impacts emissions from locomotives, while several older regulations also apply

. In June 2008, the EPA published the Control of Emission s of Air Pollution for Locomotive Engines and Marine Compression Ignition Engines Less than 30 Liters Per Cylinder. This rule includes standards for existing and remanufactured locomotives, Tier 3 and Tier 4 standards for newly built locomotives, and idle reduction requirements for new and remanufactured locomotives

. The rule reduces emissions of PM 2.5 and NO X . The emissions estimation approach used for this rule is available in Chapter 3 of the Regulatory Impact Assessment for the rule , and this approach differs from the EPA method used for the NEI

. Associated with the rule, the EPA developed a fact sheet on locomotive emission factors (April, 2009) that can be used in estimating emissions from locomotives.

4.8.6 Biogenic and Geogenic Sources Biogenic sources are a subset of natural emissions s ources 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 acti vity in the soil contributes to natural biogenic NO X and CO emissions

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

96 The EPA makes available biogenic emissions estimates as part of the NEI. Starting with the 2008 NEI, the biogenic vegetation and soil emissions have been included in the official NEI r eleases. In some cases, these EPA

- generated emissions may be sufficient for use in SIP inventories other than modeling inventories.

Biogenic emissions from vegetation and soils are computed using a model which utilizes spatial information on vegetation and land use and environmental conditions of temperature and solar radiation

. 22 The model inputs are typically horizontally allocated (gridded) data, and the outputs are gridded biogenic emissions that can then be speciated and utilized as input to photochemic al grid models

. Several models exist, as described in the following subsections.

Modeled b iogenic vegetation emissions are significant for understanding ozone formation, particularly in the Eastern U.S. , and the dependence on meteorology makes using case

- s pecific meteorology very important

. In addition, t he impact and model characterization of biogenic terpene and sequiterpene on secondary aerosol format ion for PM modeling is thought to be important

. Emissions data developers should consider the latest avai lable information on this issue where biogenic sources are key sources in their modeling region.

Biogenic Emission s Inventory System (BEIS)

The EPA has developed the Biogenic Emission s Inventory System, version 3. 6 (BEIS3. 6 ) for use in estimating biogenic emissions

. This model can be run both as part of a CMAQ model run and alternatively as a module of the SMOKE system

. The CMAQ approach is described by the CMAQ wiki at http://www.airqualitymodeling.org/cmaqwiki/index.php?title= CMAQv5.1_Biogenic_Emissions_(BEIS)_Update

. T he latest documentation on the SMOKE approach to run BEIS is available at h ttp://www.cmascenter.org/smoke/

.

The key inputs to BEIS include:

 Temperature data at 2 meters , which can be obtained from modeled meteorological data, such as data from the Weather Research and Forecasting (WRF) Model

. Such data are also needed for inpu t to air quality models used for modeled attainment demonstrations sometimes needed as part of SIPs. The BEIS3.14 documentation has more information on the meteorological inputs.

 Land

- use data from the Biogenic Emissions Land U se Database, version 4 .1 (BEL D 4 )

. BELD 4 data provides data on the 230 vegetation classes at 1

- km resolution over most of North America

. These data are available at https://www.epa.gov/air

- emissions

- mod eling/biogenic

- emission

sources

. These land use data can be created with the Multimedia Integrated Modeling System ( MIMS ) Spatial Allocator ( https://www.cmascenter.org/sa

- tools/ )

. Air agencies can alter natively rely on the EPA ’s 12

- km gridded data for modeling domains that overlap with the EPA national

22 In most cases, ozone, PM, and regional haze modeling includes the emissions from vegetation and soils , but not other potentially relevant sources such as volcanic emissions, lightning, and sea salt.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

97 domain, provided with the EPA ’s latest modeling platform on the Emissions Modeling Clearinghouse

. Other Biogenic Models

Other bio genic models such as Model of Emissions of Gases and Aer o sols from Nature (MEGAN) ( http://wiki.seas.harvard.e du/geos

chem/index.php/MEGAN_v2.1_plus_Guenther_2012_biogenic_emissions ) are acceptable as well, provided that the users have demonstrated their suitability for the modeling application through model performance evaluation (see Modeling Guidance for more information)

. A version of MEGAN has also be en incorporated into an air quality model called the WRF model coupled with Chemistry (WRF

- CHEM) ( http://www.pnl.gov/atmospheric/research/wrf

- chem/ ). California has developed a GIS

- based biogenic model called BEIGIS ( http://www.arb.ca.gov/ei/biogenicei.htm )

. The EPA previously made a comparison between BEIS and MEGAN ( available at http://www.cmascenter.org/conference/2008/slides/pouliot_tale_two_cmas08.ppt )

. BEIS, MEGAN, and other models continue to evolve and so agencies using these models should evalua te the suitability of one model over the other as part of a modeled attainment demonstration

. Once a choice has been made for modeling purposes, emissions should also be summed across the NAA for inclusion in the base year inventory for the NAA and/or the attainment projected inventory for the NAA

. 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 NO X emiss ions 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 usually less significant than biogenic

source s

. However, geogenic wind erosion may contribute substantially to PM emissions in an area

. In 2012, the EPA released CMAQ v5.0 that includes a module that dynamically estimates hourly natural emissions of fine and coarse dust particles due to wind action o ver arid and agricultural land

. This allows the contribution of this source to be included in a modeled attainment demonstration without the need to prepare an emissions inventory first

. The windblown dust approach is based on the work of J.S. Fu et al. (2 01 6 )

. For the emissions inventory SIP, air agencies using this feature should evaluate the results of the CMAQ

- based approach to determine if it provides a reasonable representation of dust emissions in their modeling domain

. Often times, CMAQ overestimate s ambient crustal matter concentrations without the addition of windblown dust and so adding emissions may not be advisable

. If windblown dust emissions are included in SIP planning , such emissions should be included in the base year and attainment projec ted inventories to meet the requirements for a complete emissions inventory

. In the case of using CMAQ, t his would require that t he CMAQ

- based emissions be summed for the NAA

. Since CMAQ produces gridded emissions estimates , air agencies would need to sum emissions from the relevant grid cells or portions of cells associated with the NAA and/or otherEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

98 geopolitical regio ns as appropriate

. One relevant detail about the AERR regarding windblown dust is that they are specifically exempted from the reporting requ irements in 40 CFR 51.20(d)
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 NO X emissions from lightn ing, are described in the EIIP document, Volume V, Biogenic Sources Preferred Methods available at https://www.epa.gov/air

- emissions

- inventories/volume

- 5

- biogenic

- source s

. 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.
Lightning produces NO, which is oxidized to NO 2 in the presence of ozone or in a photochemically reactive at mosphere

. This NO X is formed in the mid

- upper troposphere and can impact the distribution of reactive nitrogen as well as ozone. NO emissions from lightning can be estimated by collecting activity data on the cloud

- to

- ground lightning flashes, assuming a f requency of intra

- cloud flashes based on the value for cloud

- to

- ground lightning flashes, and applying appropriate emission factors (in molecules NO per flash) to these activity levels

. Because lightning is not a direct source of NO 2 , accounting for this

s ource category is more important for air quality modeling purposes than for SIP planning inventory purposes

. Given the altitude of these emissions, it is not usually important to include these emissions in the base year inventory for the NAA or in the atta inment projected inventory for the NAA

. CMAQ v5.0 includes a parameteriz ed approach to estimate NO X emissions and its vertical distribution that is generated from lightning. Over the Continental U.S., the a pproach can use lightning flash totals from the N ational Lightning Dete ction Network (NLDN). For cases where such data are not available, an alternate algorithm can be used that estimates the number of lightning flashes based on the modeled convective precipitation

. The peer reviewed literature contains both a description of the approach (Allen et al., 2011) and a model evaluation (Appel et al., 2010)

. More information is available from the CMAQ v5.0 wiki (see http://www.airqualitymodeling.org/cmaqwiki/index.php?title=CMAQv5.0_Lightning_NO )

.
4.8.7 Wildland Fires Because the CAA specifies that planning inventories (e.g., the base year inventory for the NAA) must include all sources of emissions, the inventories shou ld, therefore , include fires. Thus, wildfires and prescribed fires, including wildland fire use, should be included in the NAA inventories when they overlap with NAA boundaries. Generally, areas will find that the estimates available in the NEI will suffic e for providing a reasonable estimate of these emissions, with the purpose of providing a general idea of the level of contribution to the overall emissions within the NAA.
Wildland fires ( WLFs ) are generally defined as any non

- structur e fire that occurs i n the wild land (an area in which human activity and development are essentially non

- existent, except for roads, railroads,Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

99 power lines, and similar transportation facilities)

. The National Wildfire Coordinating Group 23 has identified the following two type s of WLFs

. 24

 Prescribed fire is any fire intentionally ignited by management actions in accordance with applicable laws, policies, and regulations to meet specific land or resource management objectives.

 Wildfire is any fire started by an unplanned ignition caused by lightning; volcanoes; other acts of nature; unauthorized activity; or accidental, human

- caused actions, or a prescribed fire that has developed into a wildfire

. Wildland fires are a unique source of emissions with respect to NAAQS attainment pla nning

. For ozone, PM 2.5 , and regional haze planning purposes, t hese fires are major sources of primary PM 2.5 and VOC and a moderate source of NO X . They can consequently impact the ambient PM 2.5 and ozone; however, they hav e a number of unique properties:

 D epending on the fuel source and acreage burned, b oth prescribed and wildfires can emit significant emissions, but emissions from prescribed fire s are generally lower due to the burning characteristics and the relative amounts of flaming and smoldering emis sions

. In addition,
p rescribed fires can be used to prevent future wildfires, which are generally larger, hotter, more dangerous, and more polluting

.

 Wildfires are naturally occurring events for which the emissions are generally not reasonable to prevent o r control

. As such, air agencies may request that the EPA exclude from regulatory determinations ambient data influenced by the wildfire if the request meets the criteria, schedule, and procedural requirements for an exceptional event set forth in 40 CFR 5 0.14. 25

 Fire emissions can rise very high in the atmosphere on plumes , and the pollutants can be transported beyond state boundaries

. Fires occurring outside NAA s can have impacts within NAA s on days that may not be determined to be exceptional events.

 Sinc e wildfires and prescribed fires generally occur in forests and rangelands, they are less likely to be within the boundaries of NAA s, which are usually urbanized areas.

 Fires can also reduce ozone formation because their smoke can block sunlight that other wise would result in more ozone.

SmartFire emissions
The EPA has adopted for use in the NEI a satellite

- based approach to estimate fire emissions at specific locations and as daily emissions. The SmartFire approach (see http://www.airfire.org/smartfire/ ) was developed by researchers with support from the U

. S

. Forest Service (USFS). T he EPA and USFS have

23 The National Wildfire Coordinating Group was formed under a cooperative agreement between the Departments of Agriculture and the Interior and consists of representatives from each of the Federal land management agencies and the National Association of State Foresters.
24 Definitions are derived from the Glossary of Wildland Fire Terminology , National Wildfire Coordinating Group , PMS 205, July 2012. Available at http://www.nwcg.gov/glossary

- of

- wildland

- fire

- terminology

. 25 “Treatment of Data Influenced by Exceptional Events; Final Rule” (72 FR 13560 , March 22, 2007 ) . EPA is updating the 2007 exceptional events rule and expects to re lease the revised final rule before October 1, 2016.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

100 worked together to implement approaches for collecting activity data from states to feed SmartFire for

use in calculating emissions

. The SmartFire approach uses the following general equation to estimate wildfires and prescribed fires. Accurate estimates of fire emissions rely on accurate estimates of the terms in the equation below.

Emissions = Area burned * Fuel Load Available * Fuel Consumed (Burn Efficiency) * Emission Factors
The SmartFire2 (SF2) approach has been used most recently for the 2011 and 2014 NEIs.

SF2 estimates the “ a rea burned” term in the above equation, in conjunction with the BlueSky framework model that estimates the last three terms in the above equation. The “fuel load available” term is estimated using the Fuel Characteristic Classification System (FCCS) maps in the BlueSky model. The “fuel consumed” term is estimated from BlueSky using the CONSUME3 model, which predicts the fraction of fuel that burns based on many parameters including fuel moisture. Finally, the “ e mission f actors” term is estimated in BlueSky using the Fire Emissions Prediction Simulator which relies on EFs from t he literature apportioned by flaming and smoldering combustion. Since SF2 was recently developed, direct references to its development in conjunction with updated BlueSky methods are not yet available; however, the following reference can be used in genera l for past applications of these process models in the SF/BlueSky process: http://getbluesky.org/smartfire/

. Reid (2013) provides more exacting details on the specific procedures used in developing the NEI p rescribed and wildfires

. As new NEI years are developed and resources are available, additional improvements to SF2 are expected.

Some states have determine that SF2 is not sufficient for their needs because the satellite

- based methods can miss detection o f prescribed burning that occurs under thick tree canopies. As a general matter, the EPA encourages all users of SmartFire to work with their forestry agencies to obtain and use local

- specific information about area burned, fuel types, fuel load, burn effi ciency, and emission factors.
Exceptional Events and Inventories
When developing design values for a particular NAA, certain ambient monitoring data may be excluded if an exceptional events submittal is approved by the EPA (see 40 CFR §50.1, 40 CFR §50.14, and 40 CFR §51.930)

. It has been suggested during the course of developing this guidance that emissions associated with exceptional events should be removed from the inventories

. The purpose of this recommendation was the improvement of model performance evaluations and projected attainment modeling.
In spite of potential impacts on modeled concentrations, in most cases, the EPA does not recommend removing fire emissions from inventories for the following reasons

. First, it is not necessary to remove fire s from use in the model performance evaluation because the EPA does not expect ambient data to be removed from the model performance evaluation ( www3.epa.gov/ttn/scram/guidance_sip.htm )

. Second , the EPA recommends holding the emissions of fires constant between the base and future years for the purpose of future year inventories (such as are required for PM 2.5 NAAQS) and for calculating a modeled relative response as part of a modeled attainment demonstration. This approach ensures that the modeled fires have a minimal influence on estimated future year concentration s that are calculated using the relative change in modeled concentrations. Third, even though in some cases there may be aEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

101 direct c ausal link between fire emissions and monitored air quality data, resulting in exceptional events, removing fire emissions directly associated with an exceptional event from an inventory require s knowledge of exactly which fire ( s ) at specific locations on specific days and hours contributed to the exceptional event . This may be especially difficult when multiple fires over multiple days lead to identified exceptional events. Therefore, from an inventory perspective, it may not be straightforward
to remove e missions specifically associated with any particular exceptional event. D etermining which

e missions to remove from the inventory could be a significant effort with limited benefit.

The EPA therefore encourages states to use a representative mix of prescrib ed fire and wildfire in their inventories. In the past, some plans under previous PM 2.5 NAAQS have estimated the actual fire emissions and temporal and spatial patterns from a given year and used this estimate as the assumed future baseline for planning, w hile others have used average emissions over multiple years. Other approaches may be appropriate as well . Moreover, regardless of the approach used, the EPA still encourages states to submit actual wildfire and prescribed fire activity data that are critic al to developing emissions estimates to the NEI as suggested in the AERR. Additionally, the EPA encourages states to consult with their EPA Regional office about the fire approach to be used. While other approaches may be more suitable in particular situat ions , the recommendations provided here provide a starting point for discussions about the most appropriate approach for a particular area.



### 4.9 Quality Assurance As part of the 8

- hour ozone NAAQS, PM 2.5 NAAQS, and regional haze rule s , state , local and tribal

a gencies are strongly 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 pr ocedures) in their IPPs.
The purpose of QA is to ensure the development of a complete, accurate, and consistent emissions inventory

. A well

- developed and well

- implemented QA program fosters confidence in the inventory and in any resulting regulatory and/or control program.
When air agencies are using data from the NEI, additional QA is warranted considering the purpose for SIPs is not the purpose for which the NEI was developed. Since a great deal of QA is done on the data used for the NEI, m o st of the QA w ork has been done and so starting with the NEI can often save time.
The overall QA program provides routine and consistent checks and documentation points in the inventory development process to verify data integrity, correctness, and completeness; identi fies and reduces errors and omissions; maximizes consistency within the inventory preparation and documentation process; and facilitates internal and external inventory review processes

. Quality

assurance activities include technical reviews, accuracy chec ks, 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.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

102 4.9.1 QA Reference Materials and Planning The EPA has d eveloped several guidance documents designed to assist state , local and tribal agencies in designing and implementing their QA programs

. The EIIP Volume VI , addresses QA issues, including the following:

 Chapter 1: Introduction

- The Value of QA/QC

 Chapter 2: Planning and Documentation

 Chapter 3: General QA/QC Methods

 Chapter 4: Evaluating the Uncertainty of Emission Estimates

 Chapt er 5: Model QA Plan

 Appendix A: Example Audit Report

 Appendix B: Technical Systems Audit Checklist Example

 Appendix C: Example 1 of Data Quality Audit Checklist

 Appendix D: Example 2 of Data Quality Audit Checklist

 Appendix E: Performance Evaluat ion Checklist Example

 Appendix F: EIIP Recommended Approach to Using the Data Attribute Rating System (DARS)

On October 2 0, 2008 , the EPA issued the latest version of the EPA Quality Program Policy (CIO 2106.0)

. This policy supersedes the previous CIO 2 105.0 (formerly EPA Order 5360.1 A2 )

. This policy established

amo ng other things, the requirement for QAPPs for all EPA

- supported programs that generate environmental data

. As described by the “EPA Requirements for QA Project Plans” guidance : The purpose o

f a QA Project Plan is to document planning results for environment data operations and to provide a project

- specific blueprint for obtaining the type and quality of environmental data needed for a specific decision or use.

The orders describing the QA req uirements are available at the EPA ’s website for Agency

- wide Quality System Documents ( https://www.epa.gov/quality/agency

- wide

- quality

- system

- documents )

. That website also inc ludes specifications for non

- EPA organizations: “ EPA Requirements for Quality Management Plans ” (EPA/240/B

- 01/001; March 2001) and “ EPA Requirements for QA Project Plans ” (EPA/240/B

- 01/003; March 2001)

. Additional documentation is also available on the same website under the subheading of “General Guidance” that air agencies may find helpful in developing their own quality assurance plans for their inventory development efforts.

States should also consult with their EPA Regional office to determine how to meet the quality assurance planning requirements for the S IP planning inventory development.

4.9.2 Types of Problems in Emissions I nventories Emissions inventories are compiled from a large number of disparate data sources, which can lead to many types of data problems

. These problems can be divided into value errors and structure errors

. Value errors are errors in the values of emissions inventory data fields, such as the emissions amounts, incorrect codes, missing values that are required, or incorrect data such as facility names, stack heights, or latitude/longitude locations. Correct q uality assurance can identify these errors and allow data developers to correct them before the data are used for their intended purpose.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

103 Structure errors refers to those data problems that cause databases to not work, such as missing records in relational database tables (e.g., “widows” and “orphans”) , duplicate records (i.e., multiple records that represent the same emissions, causing double counting), or incorrect formats (e.g., the wrong number of fields, missing fields that are req uired , mismatched data types , such as integer versus text )

. Data with no structure errors are described as having good “data integrity

. ” Generally, these types of problems should be automatically prevented by using robust data systems to manage the data in ways that match the expected downstream data use , but this is not always the case

. For example, data systems managing emissions inventory data should be developed with the AERR requirements in mind, since these are the governing requirements for SIP

- relat ed inventories.

4.9.3 Checks Available through the EPA’s Emissions Inventory System While many inventories used for SIPs are not also submitted to the EPA through its EIS (the system the EPA uses to build the NEI), the EIS does have a large number of documented QA checks that the system performs as it is loading data submitted by air agencies

. Th is automated QA provide s a large number of data integrity checks that air agencies can consider including in their own data systems or checking as part of their inventory QA

. To access a list of these checks, EIS users must use the EIS Gateway and use the “QA Checks” link under the “Reference Data” heading on the left of the Gateway interface

. The checks are not otherwise published on the EPA ’s website and can be requested by non

- EIS users by using the “Contact Us” link provided at https://www.epa.gov/chief . The list has more than 600 data checks that are performed automatically by the EIS

. While many of these checks are only releva nt for getting data into the EIS, they promote standardization of inventories and proper formatting in accordance with the AERR, which (as noted previously) provides the EPA’s standards for inventory preparation including for SIP inventories.

Since the tim ing of development of SIP inventories is rarely, if ever, coincident with the timing required for submitting emissions for the NEI, it is generally not feasible for air agencies to submit SIP inventories to EIS. However, the same types of checks can and sh ould be done on SIP inventories to insure appropriate inventory quality.

The EIS checks include both critical errors and warnings

. Critical errors prevent data getting into the EPA data system until they are corrected, whereas warnings allow the data to go through, but may need to be resolved to ensure the data transmitted to the EPA are correct

. Examples of critical errors include:

 Checks that data codes for required fields use valid values ( for the given inventory year ; see also Section 4.7 )

 Fields required by the AERR and for data integrity are present

 Certain fields are within a critical range check (e.g., a year is between 1900 and 2050 , stack height is between 1 and 1300 meters )

 Certain fields have appropriate lengths (e.g. , ZIP codes are between 5 and 10 characters)

 Percentages are provided as percentages (1 to 100) and not as a fraction

 Data element types (e.g., integer, text, numerical) of required data fields are provided consistent with their required type.

 MOVES county database submission contains the correct filesEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

104  NMIM county d atabase submission contains the correct files

 Conflict with pollutants reported for grouped pollutants versus individual members of the
group.

 If stack diameter information is reported, the relea se point exit gas flow rate or velocity should be reported. Both may also be reported.
Examples of warnings include:

 Checks that data codes for optional fields use valid values (for the given inventory year)

 Data value is longer than the allowable width (s ome text fields will be truncated if longer than what the EIS allows).

 Emissions value is outside of a presumed valid range

 Exit Gas Stack temperature is outside an appropriate range

 When submitting monthly data, all months are not submitted together

 File names of mobile data files use in correct file extensions

 Data element types (e.g., integer, text, numerical) of optional data fields are inc onsistent with their required type.

4.9.4 Inventory Comparisons Inventory comparisons can be used in multiple ways to effe ctively identify problems in new inventories. This is most useful when a high

- quality prior inventory is already available. In states with a long history of developing SIPs, past inventories will be readily available for such comparisons. In states with ne w or emerging attainment problems, the EPA suggests comparing SIP inventories to the NEI. Even when the comparisons reveal problems not with the new inventory but with the one being compared, this can increase confidence in the inventory of interest.

Emiss ions are one of the obvious things to compare, and these comparisons are usually done on a pollutant

- by

- pollutant basis for pollutants important to a given analysis. As noted in the section on ranking techniques (Section 4.9.7 ) , ranked emissions (e.g., facility, unit, county, SCC group) can be compared to the same ranked emissions from other inventories. Such comparisons will often identify differences worth further exploration when one large source appears on one list and not t he other.
In addition to ranking, all records across an inventory (or inventory summary) can be compared and percent differences can be computed. This is usually done by computing “ new emissions

– old emissions ” divided by “ old emissions

. ” Large or unexpe cted percent differences can be investigated further to make sure that the differences have some reasonable explanation, such as newer emissions being controlled, a downturn in activity for one inventory, process changes, fuel changes, or a partial or
comp lete facility closure. In some cases, methods changes may be the reason for such differen ces, including updated emission factors or test data.
For nonpoint emissions, graphical inventory comparisons can be useful. This can be done by not only using calcula ted percent differences or ranking, but also using GIS techniques to map county level emissions and their differences. It can be very useful to map the old emissions, new emissions, and theEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

105 computed difference or percent difference side

- by

- side. This can r eveal areas of large emissions that have significantly changed from one inventory to the next, raising questions for further exploration. When comparing to an EPA inventory that used EPA methods for a particular sector, this could reveal that the SIP plann ing inventory is a better inventory with updated methods, or it could reveal that outdated methods are being used. In any case, making the comparison will help inventory developers understand the potential improvements that could be made or that have been made, which will help in understanding reviewers’ expected reactions to the data.

For multi

- state inventories needed for SIP development, state

- to

- state comparisons may be useful in addition to county maps. This is especially true if emissions for one stat e were developed differently from emissions for another state. The EPA encourages states to work together to promote consistent approaches across a multi

- state NAA, but a final QA check of the consistency can be done using the comparison techniques describ ed here.

4.9.5 Checking Data C odes As described in Section 4.7 , air agencies should check the inventory data codes they are using against valid codes

. Valid codes are defined by the EPA within the EIS. Air agencies that start with t he NEI may significantly minimize the burden of this recommendation.

4.9.6 Point Versus N onpoint and R econcil i ation Several quality assurance issues arise related to point versus nonpoint sources and inventories: (1) correct identification of point sources, (2) prevention of double counting across point and nonpoint, and (3) prevention of missing nonpoint emissions.
Minimum thresholds are specified in the AERR for which sources with facility total potential to emit emissions above those thresholds must be treated as a point source in SIP planning inventories

. This is more fully explained in Section 2.5.7 , with lower thresholds relevant for ozone and PM NAA s

. Air agencies should implement a QA check (or otherwise have a data collection process) that ensures all facilities with potential emissions (potential controlled emissions, if applicable) that are greater than these thresholds are included in their inventory as point sources

. See also Section 2.5.2 for m ore information on calculating potential emissions.

When a particular type of source include s contributions from both point and nonpoint sources, double counting can occur

. Q uality assurance steps should be taken to ensure that double counted emissions hav e been prevented

. A good example of this is smaller boilers

. Both point source facilities (based on the potential to emit thresholds) and smaller facilities are likely to have emissions from non
- industrial boilers

. For instance , some large institutional fa cilities such as hospitals may be included as a point source with their associated boiler emissions, whereas smaller institutional facilities are not included as point sources and would thus be included as a nonpoint source under an “institutional/commerci al” boiler SCC

.
The EPA provides calculation approaches for many nonpoint emissions that allow for subtracting out the activity of the point source parts prior to estimating nonpoint emissions , including that for the institutional/commercial boiler exampl e

. This is called “point/nonpoint reconciliation

. ” WhetherEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

106 nonpoint emissions are estimated by the EPA or by air agencies, a n assessment of quality s hould be done to ensure that sectors associated with both point and nonpoint sources do not double count

em issions . See also Section 4.8.2 for additional information on preventing double counting. A list of source sectors with potential point/nonpoint overlap is provided in Table 17 above and in the latest NEI Technical Support Document, available at https://www.epa.gov/air

- emissions

- inventories/national

emissions

- inventory

. A third type of QA should be done for catego ries that have both p oint and nonpoint contributions

. It involves an assessment of potentially missing nonpoint emissions

. Because the requirement for SIP inventories is to include emissions from all sources, it is not sufficient to exclude nonpoint emissi ons when part of a sector is covered by point sources, unless it can be shown that the nonpoint portion is negligible

. At a minimum, air agencies should consider the tools available from the EPA to estimate nonpoint sectors (see Section 4.8.2 ) and evaluate whether or not their point source inventory covers all of the activity associated with the nonpoint categories

. For inventory years not covered by EPA tools,

a gencies should compare point total activity as collected from point sources versus the same type of activity data used in the EPA tools

. For example, U

. S

. DOE fuel consumption data can be used for industrial, commercial, and institutional boilers

. The source of the activity data used for the latest EPA nonpoint methods is included in the descriptions of those methods in the nonpoint tools described in Section 4.8.2 and with the latest NEI documentation.

4.9.7 Ranking Techniques Ranking emissions records can be a very useful tool to identifyin g value errors in emissions values or other numeric inventory data fields, or at least in finding records that need further investigation

. Ranking involves first defining a set of sources and a level of aggregation of emissions and then ordering those emissions va lues from highest to lowest or lowest to highest

. This analysis must be done one pollutant at a time

. An analyst then considers whether those sources at the top of the list make sense.
Point sources, facility level emissions ranking
For point sources, rank ing can be done at the facility total, unit total, or process level (i.e., at the SCC level) , and each level has its place for reviewing inventories

. A facility level ranking can often be followed by subsequent investigation to understand the reasons (at t he unit and/or process level) for very high or very low values

. An analyst using a ranking pro cedure would assess the facilities with the largest emissions and seek to understand whether they make sense

. For example, f or combustion products such as NO X or SO 2 , one would expect to see large EGUs and other industrial sources

. Ranking of emissions values is usually done for one pollutant at a time, reviewing most carefully those pollutants that are most critical to the particular purpose of the inventory

. For example, an inventory supporting ozone analysis would want to review NO X and VOC most carefully.
It can be useful to compare the list of top facilities for a given pollutant from one inventory to a previous or alternative inventory for a given state or NAA

. This can raise q uestions regarding large changes from one inventory to another, which could be explained (e.g., a decrease due to controls) or could identify a problem (e.g., a missing value or data entry problem)

. In addition, facility

- level ranking can useEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

107 additional grouping such as by industry code (i.e., NAICS), to identify unexpectedly high or low emissions for facilities within a particular industry.
Point sources, sub

- facility emissions ranking

Unit

- and process

- level summaries can additionally be ranked for more specific analyses

. For example, all boilers could be ranked and particularly high or low emissions values investigated

. Similarly, all natural gas processes at particular unit types (e.g., boilers) or by industry (NAICS) could be ranked

. T hese rankings can show real variations, but they can also find incorrect values that stand out when ordered and reviewed in this way

. There are many variations that could produce useful results, and which ones are useful for a particular inventory depends on many factors and the purpose of the inventory.
Nonpoint and mobile source ranking

N onpoint and mobile emissions can also be ranked as technique to help with QA

. Since these inventories are primarily compiled at the county/SCC resolution, the ranking can be done only at combinations of county, SCC, and for specific pollutants

. Total county nonpoint emissions could be ranked to look for overly high or low values, but the same effect can be accomplished in a visual way with mapping approaches (see Section 4.9.9 )

. Specific SCCs can also be selected and the emissions by county ranked, or individual counties selected and SCCs ranked and compared to other counties.
Since nonpoint emissions are based on various types of activity data that also has a county or other spatial resolution (such as census tract), these activity data can be used to “ normalize” the nonpoint emissions prior to ranking

. For example, emissions coming from households (e.g., residential heating, residential wood co mbustion, consumer solvents) can be divided by population or housing data and ranked for identify possibly strange results

. Since some of the activity data used for these categories starts with state or regional resolution and is subdivided to apportion to the county resolution, such comparisons can reveal illogical outcomes of such approaches

. For example, while it makes sense that residential wood combustion occurs more per household in rural areas, it wouldn’t make sense for a very low population county to have a dispr oportionate amount of emissions and urban areas have none.

4.9.8 Outlier Analyses One result of the ranking approaches described above will be to identify outliers

. However, such ranking is a relatively unsophisticated way of identifying such outl iers

. A more robust approach can be used for point sources where states have the underlying activity data reported by facilities on a per

- process basis

. Dividing emissions by activity values would produce a set of implied emission factors, or rates. The

ra tes for a similar set of processes (based on SCC) and control devices in use might be expected to be within an order of magnitude of each other. Emission rate values that are too far outside the expected relationship could be further investigated to better understand the source of any unexpected values, which might include an error in the units of measure or the presence of controls or an incorrect SCC, as well as data entry errors for emission values or other related fields.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

108 4.9.9 Using Maps to QA Nonpoint Emiss ions Nonpoint and mobile source emissions data are associated with states and counties and , therefore , are ideal candidates for mapping with GIS software

. By mapping emissions values for individual SCCs or groups of SCCs, data analysts can identify unexpec ted patterns in the data that could signal an error in creating the data

. Though it is technically more challenging to use GIS software, this approach can often be more valuable than ranking in identifying data problems.
Like the ranking techniques, GIS ma ps can also use emissions data normalized by some other underlying or related spatial data, such as population, land use, urban/rural designations, or housing

. This type of information is increasingly available online from the U.S. C ensus B ureau and other sources

. Data analysts can use the other data to identify unexpected relationships that possibly indicate bad assumptions made in the underlying methods.

4.9.10 Expected Pollutants A ir agencies can use their expertise with emissions sources to identify which poll utants are expected from particular processes

. In addition, for the 2014 NEI cycle, the EPA has provided a list of expected pollutants for each SCC

. While this list is not comprehensive for any pollutant that can be associated with a process, it provides a bare minimum of essential pollutants associated with SCCs

. For example, NO X is always expected as a by

- product of combustion processes

. In addition to expected pollutants, analysts can also identify pollutants that are not expected from a particular proce ss, such as SO 2 from an evaporative process

. Once identified, such lists can be used to cross

- check inventories to identify either problems with reported emissions, pollutant codes used, or process codes used

. For example, if a combustion process does n o t have NO X emissions, it could be that the wrong pollutant code was used in reporting the NO X and its showing up as something else

. Or, the process itself may be incorrectly using a combustion process code.
Expected pollutants can also help with making sure the correct PM components are provided for PM inventories, in particular that condens a ble PM emissions are included in the total PM emissions and that both filterable and condensable PM emissions are reported

. This issue was described in Section 4.2.1 along with a list of the types of sources expected to have such emissions.
Some emissions data analysts may not be familiar with various sources enough to know which pollutants should be expected

. For point sources, agency staff c an rely on the sum total of all reported data across multiple sources for a particular process to get a good idea of what should be expected

. For example, if all but one industrial boiler burning natural gas reported VOC, then it would be worth further inv estigation as to why VOC was not reported for that one

. Since the AERR specifies that all criteria pollutants must be reported if any one pollutant exceeds the potential to emit threshold, one should expect that similar processes from multiple facilities w ould have many, if not all, the same pollutants.
There are other ways to identify expected pollutants

. These include looking at past inventories created by the same air agency or looking at the NEI

. Another way is to see what emission factors are available for the process in Webfire

. While these are not foolproof ways of finding expected pollutants, they canEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

109 be very helpful

. Comparing a draft inventory with such a list can also identify unexpected pollutants to consider

. Used with ranking techniques, knowin g what pollutants are expected can also help when you find zero or null values for a facility, unit, or process.

4.9.11 Facility and Release Point Locations Facility and release point (e.g., stack) locations are key elements of inventories that are used primarily in preparation of inventories for air quality modeling and also in permit modeling

. Facility locations are also used in mapping point sources for various public communications purposes or other reasons needing less precision . While facility resolution is acceptable for many modeling applications, including 12

- km gridded modeling, the need for release point locations increases for finer resolution modeling. Thus, for 4

- km or 1

- km modeling, release point location information should be considered.
With regard to the more detailed release point coordinates, the EPA recognizes the need for air agencies to leverage SIP inventory development efforts for possible use for other inventory needs. Thus, air agencies should be particularly attuned to release point geogr aphic coordinates for sources that could be involved in permitting or risk analysis. For regulatory dispersion modeling, release point location is critical (rather than only facility location).
The EPA’s EIS and other inventory data systems support two typ es of locations: facility and release point

. There are four key errors that can occur, and each can be identified with their own type of check, as listed below.

 Facility is not consistent with the state/county FIPS code This error can be found using GIS , S AS ® or other calculations to compare the latitude/longitude location with the county boundaries using some tolerance

. Because county boundaries have varying degrees of accuracy, a tolerance should be used that allows for locations near, but not always 100% within, county boundaries.

 Facility location is not consistent with the physical location of the facility Since some facilities can be on very large tracts of land, facility locations developed using geocoded addresses or facility entrances are often not accurate with regard to the actual location of the facility

. For emissions inventory purposes, the EPA encourages that facility locations be positioned on top of a part of the facility that emits one or more pollutants , and the facility centroid is often s ufficient for doing so

. Using freely available mapping software such as Google Maps, latitude/longitude locations can be plotted on satellite images to ensure that values are on top of an emitting source and not on the road, at the corporate headquarters, or in some other invalid location.

 Release point location is not consistent with facility location This check is only useful once th e facility location is accurate

. Such an error can be found using GIS, SAS® or other calculations to determine the distance between the facility location and the release point locations

. Alternatively, a subtraction of the absolute values of the latitudes and longitudes can be used to determine the difference in degrees. If that linear distance or the distance in degrees is gre ater than some preset criteria, th e n the locations can be investigated further

. For some types of facilities such a s refineries or major chemical complexes, the facilitiesEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

110 may be very spread out and therefore may have legitimately large distances between r elease points.

 Release point location is not consistent with the physical location of the release points For many applications, including some SIP modeling applications, all release points using the same (usually facility) latitude/longitude is sufficient

. However, with the availability of inexpensive GPS technology, it is more realistic for facilities to collect and submit individual release point location information

. Furthermore, for some types of analysis, particular fine scale modeling for permitting a nd risk analysis, correct release point locations can make the difference between a good analysis and a useless one

. It is very difficult to check the accuracy of release point locations, but using mapping software overlaid on satellite images can provide some sense of whether the release points are meaningful or not

. Coordinates reported to one

ten

- thousandth of a degree (four digits after the decimal point) give a precision of approximately 30 feet. Thus, a simple check to see if such values are useful is to examine the number of decimal places included in a given database.
Since a facility’s location is not likely to change, the EPA has implemented a procedure in the EIS that allows latitude/longitudes to be locked, meaning that they cannot be changed acc idently during a data exchange with a state

. We encourage air agencies to implement a similar approach in their data systems so that the efforts of QA done on one inventory can be inherited by other inventories created by that
agency

. Locking mechanisms pr event the data from being changed inadvertently through a new data collection that relies on data from an unverified data source. Thus, a comparison of the locations used in the SIP inventory to any locked and verified site coordinates in EIS would also hi ghlight potential errors.

4.9.12 Release P oint P arameters Like release point locations, release point parameters (also called stack parameters) are key elements of inventories that are used primarily in preparation of inventories for air quality modeling

. The rel ease point parameters impact the modeling of emissions from facilities because they specify details of the way the emissions are released (e.g., they specify how high off the ground the pollutants are emitted and the exit velocity and temperature of those emissions )

. One basic and important distinction for release points is whether the release point is a stack or a fugitive emissions, and different types of parameters are specified for stacks than for fugitive emissions sources.
Correct release point param eters for stacks are important for modeling done for o zone and PM 2.5 modeled attainment demonstrations as well as modeling done for Regional Haze SIP s , whereas fugitive release parameters are not as critical for that purpose

. This is because stack emission s parameters impact the modeling of plume rise and therefore determine how high the emissions rise in the modeled layers of the air quality model

. Fugitive emissions are emitted in the modeled surface layer with no additional characterization

. This is in c ontrast to more detailed plant

- level modeling (i.e., done for permit modeling or risk modeling purposes), where b oth stack and fugitive parameters are critical. Because the focus of this document is on SIP purposes, we focus on stack parameters here.

Stack parameters included in the EIS and historically are stack height, stack diameter (at the exit point of the emissions), exit gas velocity, exit gas flow rate, and exit gas temperature

. Additionally, a releaseEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

111 point type is available in the EIS to specify a code for whether the “stack” has a particular orientation of vertical, horizontal, goose neck, vertical with rain cap, or a downward facing vent

. Valid release point codes are available in the EIS reporting code tables in the EIS Gateway.

Q uality assuranc e for stack parameters can be done using several of the QA methods already described

. Range checks can be applied ; these can be the default EIS range checks (see Section 4.9.3 ) or range checks developed by a n air agency

. A more robust range check could be developed for specific types of processes associated with a release point or for specific NAICS codes

. For example, one would expect higher stacks for EGUs than for lumber mills

. Additionally, ranking techniques can be applied to stack parameters (see Section 4.9.7 ), including options for grouping ranked stack parameters b y facility, unit, process and/or specific types of facilities, units, or processes

. This is somewhat complicated by the fact that multiple units or processes can feed a given release point, and when this happens, the predominant unit or process could be used for grouping purposes

. Finally, more sophisticated outlier analysis could additionally be used, by finding correlations between stack parameters such as height and diameter and investigating those combinations that statistically fall outside an expected relationship or ratio.

4.9.13 Biogenic QA/QC Biogenic emissions are somewhat more challenging to QA than emissions for other source cate gories because they may be generated differently (i.e., as part of a gridded, hourly modeling exercise rather than more basic inventory development techniques). The following list provides some basic checks that can be done as part of the generation of bio genic emissions:

1. Check the biogenic emissions tool logs for warnings/errors.

2. Check the logs to confirm that the expected inputs were used

.
3. Compare state or county total emissions to another year or case ’s biogenic emission totals.

4. Ensure that summer emissi ons are greater than winter emissions

. This can be done by summing the emissions across the modeled summer days (e.g., May

- October) and for the other models and then comparing the totals on a state and/or county basis

. As a quick (but less rigorous) check, example summer hourly or daily emissions can be visually compared to example winter hourly or daily emissions using software that displays the gridded emissions.

5. Visually inspect sample days of the gridded, hourly emissions using software that displays th e gridded emissions

. The VOC emissions should generally be higher in southern latitudes because of warmer temperatures

. This difference should be more pronounced in winter in cases where the southern areas have more actively growing vegetation

. The NO emis sion should generally be higher in agricultural areas with signi ficant fertilizer application.

4.9.14 Timing of QA and F ollow

- up As air agencies , as well as the EPA Regional office s, work quickly to meet relevant inventory and SIP deadlines, data problems are exa cerbated when they are discovered too late in the process

. A key part of making sure that a QA plan is effective is deciding (as part of the planning) when a given QA check isEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

112 to be done and ensuring (as part of implementing that plan) that it is actually done

. To do this effectively, QA steps should be timed in a QA plan at the earliest possible time that the step can be performed so that errors are caught as early in the process as possible

. Furthermore, assurances must be put in place that someone is con firming that the checks have been done along the way, so that errors

are caught

. At the end of the data development process, some accounting for the history of the QA should be available along with the data, so that others can confirm that the checks have been done and can be reassured

. Where possible, evidence of completion of each QA step should be referenced, such as a comparison report.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

113 

## 5 Developing Projected Emissions Inventories

5.1 Projected Emissions Overview Emissions estimates for future years 26 are call ed “emissions projections” or “projected emissions

. ” These projections include emissions growth (due to increased or decreased activities) and emissions controls due to regulations, settlement agreements (or con s ent decrees), fuel

- switch es, or other progra ms that reduce emissions in specific ways in the future

. Emissions controls can be either on

- the

- books or considered as part of a control strategy to reduce emissions as part of SIP planning. For point sources, emissions projections can also include facili ty and/or unit

- level shutdowns due to settlement agreements ( or consent decrees) and/or ownership decisions.
The primary goal in making projections is to obtain a reasonable and technically credible estimate of future

- year emissions that accounts for key variables

. The EPA encourages the air agencies to incorporate in their analys es the variables that have historically been shown to drive their economy and emissions, as well as the changes in growth patterns and regulations that are expected to take place between the time of their base year and projected attainment year

. For details on which future year(s) should be modeled for attainment demonstrations, readers should refer to the Modeling Guidance ( https://www3.epa.gov/ttn/scram/guidance_sip.htm ).

5.1.1 Readily Available Projections Information The EPA’s latest projection approaches and data are available as a part of the EPA ’s “ emissions modeling platform” development

. These platforms are released and updated periodically in accordance with the EPA regulatory and analysis activity on the Emissions Modeling Clearinghouse at https://www.epa.gov/air

- emissions

- modeling . While each platform comes with a single or limited set of future years included, the data and thoroughly documented approaches can help air agencies to develop and improve their own emissions projections.
Additionally, as part of SIP planning, various situations lead to requiremen ts for states to implement Reasonably Available Control Technology (RACT) and Best Available Control Technology (BACT) as part of their attainment planning. The emissions reductions expected based on these programs would need to be include in emissions pro jections used for modeled attainment demonstrations and other projected emissions such as the projected attainment inventory for the nonattainment area (see also Section 3.8.1 ).

5.1.2 Background Materials For point sources, Volume II “Point Sources” of the EIIP series includes Chapter 12 “ How to Incorporate the Effects of Air Pollution Control Device Efficiencies and Malfunctions into Emission Inventory Estimates ” was published in 2000 and still provides the authoritative information related to point source projections. In particular, Appendix A “Clearing Up the Rule Effectiveness Confu sion” and Appendix B

26 Technically, projected emissions could be made from a base year to a year that has already occurred when data are not yet available for a very recent year. However, for the purposes of the remainder o f this guidance, we will assume projected emissions refers to future year projected emissions.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

114 “ Emission Inventories and Proper Uses of Rule Effectiveness” provide a thorough discussion of rule effectiveness that is relevant for current emissions projections.

In addition , the 1999 EIIP report entitled “Procedures f or Preparing E missions Projections” ( https://www.epa.gov/air

- emissions

- inventories/volume

- 10

- emissions

- projections

- final

- report ) introduces the basic concepts behind emissions projections issues and approaches. T he concepts of control efficiency, capture efficiency, rul e effectiveness, and rule penetration are introduced in Section 2.5.18

. The EIIP document provides information on how to use these factors to estimate projected emissions

. However, some key features of this document need to be updated, including the reference to the Econ omic Growth and Analysis System , which is no longer supported by the EPA

. Other outdated concepts include the assumption that economic growth can be a good indicator of emissions growth

. While some correlation ca n exist, it cannot be assumed but rather must be demonstrated for a particular industry or facility. The correlation has not been well observed historically in the NEI data because of various issues including technology improvements and fuel

- switching that often reduce emissions without regulation

. In this section, we will address an overall approach for tackling emissions projection issues that incorporates use of this document and points out where other approaches or new data are available to amend the in formation included in that report.
Some general aspects of the EIIP projections document that are now out of date are as follows.

 The latest SCC codes are available as described in Section 2.5.14

.
 The AP

- 42 emis sion factor website is now https://www.epa.gov/air

- emissions

- factors

- and

quantification/ap

- 42

- compilation

- air

- emission

- factors

.
 The referenc e in the Table 2.1

- 1 web link is no longer applicable. Instead, the following information can be used to help provide similar information:

o Energy consumption by industry report, 2002: http://www.eia.doe.gov/oiaf/analysispaper/industry/consumption.html

o Annual Energy outlook report, early release 2014: http://www.eia.gov/forecasts/aeo/er/index.cfm

 The references i n Table 2.1

- 2 are also out of date and should be updated as follows:

o U

. S

. EPA Emissions trends reports

. These reports can be used to provide the historical trends of emissions sectors based on the NEI : https:/ /www.epa.gov/air

- trends

o Integrated Planning Model: See reference provided above in Section 1.2

o Multiple Projections System

- is no longer in use

o California Emission Forecasting System: http://www.arb.ca.gov/ei/drei/maintain/database.htm

The EPA recommends that d evelopers of project ed emissions take the steps in the bulleted list below. Each of these steps corresponds to a subsequent subsection.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

115  Identify sectors of the inventory that require projections and sectors for which projections are not advisable, and prioritize these sectors based on their expected impact on the modeling region (Section 5.2 ).

 Collect the available data and mo dels that can be used to project emissions for each of the sectors (Section 5.3 ).

 For key sectors, determine what information will impact the projection results the most, and ensure that the data values reflect conditions or ex pectations of the inventory region (Section 5.4

.

 Quality assurance (Section 5.5 )


### 5.2 Identify and Prioritize Key Sectors and Regions for P rojections Emissions data developers should evaluate their inven tories for those sectors and regions that are most critical to their modeling results

. The purpose of identifying these key sectors is to direct more resources and efforts to estimating future

- year emissions for these sectors in the subsequent steps.

Secto rs can be subsets of the larger groups of stationary area, on

- road mobile, nonroad mobile, and point sources

. For ozone modeling, it will be most important to ensure correct projections for sectors with higher NO X emissions . In larger urban areas that cont ain VOC

- limited regions, sectors with higher VOC emissions will also be important

. Mobile sources are typically large contributors to both VOC and NO X ; therefore, they are usually a priority in estimation of future

- year emissions, particularly for urban

ar eas

. For PM and regional haze modeling, the relative importance of primary PM 2.5 emissions and its precursors will depend on the area of the country

. Primary PM 2.5 emissions may be important in urban areas or areas heavily influenced by local sources such as residential wood combustion or industrial facilities

. In the East, SO 2 emissions may be of primary importance

. For PM 2.5 planning, NO X , VOC, and NH 3 will vary in importance depending on the particular situation, which needs to be assessed as part of the SIP planning process.
Emissions data developers should consider the proximity of the emissions and the expectation of long

range transport when reviewing projection assumptions. Those emissions that have an impact on the nonattainment status (whether tran sported from outside areas or locally generated) should be given highest priority in evaluating the projection assumptions. For example, less priority can be given to emissions from distant states and/or for pollutants that do not transport from those stat es to the NAA

. In some cases, there are sectors that are very difficult or highly uncertain to project into the future

. Wildfire emissions is a common example of such a sector, since models are not readily available that estimate the magnitude and location of future

- year emissions

. In these cases, it is reasonable to create an “average year” inventory and temporal distribution of the emissions. Other approaches to future

year fire emissions include holding the emissions constant at the same levels as includ ed in the base
year.


### 5.3 Collect A vailable D ata and M odels for Each Sector Needing P rojections For each sector needing projections (and in particular for the priority sectors), air agency staff should collect and review growth and control information

. The sour ces of such information depend upon theEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

116 sector of interest

. Some data resources and approaches are available and provided here, and new data and approaches will become available subsequent to the publication of this document

. The information provided here is a snapshot of information that will grow and adapt over time, and emissions modelers should seek out such new information as part of this step.
Emissions modelers can rely on available default data for sectors and regions with lower priority for conside ration (as described in the previous section)

. For sectors and regions that are important to modeling the NAA , emissions modelers should spend additional effort obtaining improved information from other modeling applications (such as modeling done by RPOs or other state s) or developing the improved information themselves.
As mentioned previously, the EPA provides control assumptions with its modeling data used for promulgating air quality rules and impact assessments . The EPA approaches typically include th e impacts of federal rules that have been finalized. Impacts of proposed rules are rarely included, as the changes in emissions impacts can be very large between the proposed and final rules. These data are posted at the Emissions Modeling Clearinghouse

. Sometimes, more current information is available than what is available from the EPA , for example, when reconsideration amendments are developed and finalized after the EPA has publicly released its projected inventories

. In the subsequent subsections, we focus on sources of growth information.

5.3.1 Electric Generating Units This section conveys the general principles and key criteria that inform development and review of EGU emission projections in suppo rt of CAA

- related state regulatory actions (such as SIPs) subject to EPA approval. The section includes technical information related to EGU emission inventories, key modeling/projection input assumptions, appropriate data sources, and general methodologic al criteria to be used by sta tes and EPA Regional offices.
This guidance does not recommend or restrict the use of any specific tool to generate credible projections of EGU emissions. It explains a process for documenting credible data and input assumption s with accompanying justifications; describes how to demonstrate a reasonable relationship between inputs and outputs for a given application; and identifies relevant resources that should be taken into consideration.
Emission projections for EGUs do not t end to follow a simple growth path from historical emission data

. The composition and behavior of the generating fleet, and resulting power sector emission patterns across facilities, states, and regions, vary substantially over time based on changing econ omic conditions as well as changes in fuel markets and regulatory requirements

. Therefore, evaluating the credibility of power sector emission projections necessitates evaluating the reasonableness of several key projection elements or assumptions, while k eeping in mind that appropriateness of the method also depends on the span of future year(s) being projected ( the “ modeling horizon ” )

. These projection elements include:

1. Electricity demandEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

117 2. The composition of the future generating fleet If the future year(s ) provides enough lead time, consideration of economic entry (new facility construction) and exit (existing facility retirement) that would change the composition of the fleet

.
3. Generation pattern across facilities that is consistent with economic factors, power system operability, reliability, and environmental regulatory constraints

4. Potential emissions at each generator, taking into account pollution content of available fuels as well as the ability of control equipment or processes to capture that polluti on State, tribal and local agencies have the choice to independently develop power sector emission projections or to use emissions projections from other entities (federal or regional bodies, including RTOs and ISOs)

. If a state, tribal or local agency cho oses to develop independent projections (or to derive such projections from other available forecasts), data sources should be referenced and clear justification should be stated for the projection methodology, including a clear demonstration of the relati onship between demand, cost, generation capacity and emissions. Documentation supporting any set of power sector emission projections should include:

1. Inventory of all sources of generation accounted for in the projections, including but not limited to all individual emitting EGUs

2. Information regarding electricity demand for the future year

a. The demand forecast for EGU projections should be referenced and documented (potential sources include AEO, NERC, regional transmission organizations, independent system operators, state energy offices or public utility commissions, and regional councils that develop energy planning).

3. A detailed profile of future capacity, including:

a. Projected changes to the operable fleet, such as retired capacity, new capacity, changes
t o capacity type (e.g., refueling), and pollution control retrofits b. Physical characteristics of the operable fleet, including capacity, fuel type, heat rate, and pollution controls (i.e. , list of emissions controls and their associated removal efficiencies for pollutants of concern)

4. A detailed profile of projected power system operation, including generation, fuel use, and emissions

5. A detailed list of all of the constraints (with the corresponding future compliance dates) that apply to reduce emissions at one or more sources, such as:

a. Federal, s tate and local rules b. NSR settlements

c. Consent decrees d. Rate or permit requirementsEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

118 e. All other on

- the

- books regulatory requirements

6. Representations of the following, or if not directly factored in, reasoning and method ology explaining how these elements are accounted for indirectly:

a. Fuel supplies and/or prices b. Generator availability constraints

c. Minimum generation requirements (such as qualifying renewable energy ( RE ) generation to meet RPS targets) d. Cost and performance characteristics of existing and potential new generation and pollution control technology options

e. Transmission, reserve margin, and other system operating constraints

7. Unit

- level generation, fuel type and use, pollution control configuration, and emissions

8. Any other information used in and/or relevant to the projection

E lectric generating unit projections for different purposes (such as attainment demonstrations, maintenance plans, and reasonable further progress plans), as well as varying factors such as p ollutants, geographic areas, and/or how far the projection period is into the future, may prompt adaptation of different approaches

. There are two main types of methodologies states can consider when projecting EGU emissions for SIPs : optimization methods and non

- optimization methods.

1. Optimization methods are those that use computational algorithmic models that seek the “least

- cost” optimal dispatch based on economic assumptions while obeying physical constraints of generators within the selected universe of EGUs

. Examples of typical constraints within an optimization method include, but are not limited to, ramp rates, outage schedules, transmission limits, system reserve margin limits, and emission limitations

. Optimization methods are generally used for l onger
- term projections at the national or regional scale

. In some cases, optimization approaches may under

- represent non

- economic factors that affect unit operations.

2. Non

- optimization methods are those that follow a prescribed set of rules and relationship s to simulate the behavior of EGUs based on electricity demand trends, historical electricity production trends and data from other forecasting models. Generally, these frameworks employ statistical analysis or algorithms to estimate how EGUs will generate in a future year based on certain expected conditions

. To the extent that these methods are based largely on past EGU behavior, their projections can be relatively insensitive to potential changes over time in economic and regulatory factors that affect E GU behavior. These non

- optimization methods are generally used for shorter

- term projections at the regional, state, or local scale.
Whether a state uses an optimization or non

- optimization EGU projection method, states should provide information to EPA tha t documents the methodology and how the chosen projection method adequately addresses the analytic drivers described above, in the context of the associated regulatory action and with the timeframe of the projections taken into account

. For example, for a given area,Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

119 there may be a reasonable justification to use recent historical data to represent fleet behavior in the near future (e.g., 1

- 5 years). However, projecting for years farther into the future (e.g., 10

- 20 years) may necessitate an optimization ap proach in order to allow for a better representation of the economic and regulatory drivers that affect fleet behavior and associated emissions.
A state may also consider whether limited modifications to other EGU projections (such as those provided by EP A, EIA, or ISO/RTOs) may reasonably address the analytic drivers described above

. Such an approach should include documentation of where and how the modified set of EGU projections differs from the unmodified (original) set of projections, and why it is ap propriate for the given regulatory action or future scenario to make such modifications without conducting a more thorough or complete analysis

. 5.3.1.1 Existing Material for More Information The resources listed in this section can provide additional information that may be helpful for EGU emissions projections.

Guidance for 1

- Hour SO2 Nonattainment Ar ea SIP Submissions

. This document describes non

- binding recommendations on a wide range of issues that are likely to arise as state, local and tribal governments de velop nonattainment SIPs for the 1

- hour SO2 NAAQS. This document is available at https://www.epa.gov/so2

- pollution/guidanc e
- 1

- hour

- sulfur

- dioxide

- so2

- nonattainment

- area
- state

implementation

- plans

- sip

. Roadmap fo r Incorporating Energy Efficiency and Renewable Energy in SIPs/TIPs

. This document provides a roadmap to assist state, tribal and local agencies with accounting for and incorporating energy efficiency (EE) and RE policies and programs in SIPs and TIPs. The roadmap accomplishes this task by clarifying guidance the EPA issued in 2004 on incorporating EE/RE policies and programs into SIPs, as well as related guidance EPA issued in 2004 and in 2005

. This document is available at https://www.epa.gov/energy

- efficiency

- and

- renewable

- energy
- sips

- and

- tips/energy

efficiencyrenewable

- energy
- roadmap

. Resource for States on estimating EE/RE relative to EIA’s Annual Energy Outlook for SIPs

. This document helps states identify their on

- the

- books energy efficiency and renewable energy policies and estimate the incremental electricity savings of these policies; develop a methodology for projectin g a jurisdiction’s energy demand both with and without the incremental electricity savings; and estimate the change in power sector emissions attributable to the incremental electricity savings

. For more information visit: https://www.epa.gov/sites/production/files/2015

- 08/documents/ including_ee_and_re_policies_in_ed_projections_03302015_final_508.pdf

. Assessing the Multiple Benefits of Clean Energy Pro grams: A Resource for States

. This document helps state energy, environmental, and economic policy makers identify and quantify the energy, environmental ( specifically greenhouse gas, air, and health ), and economic benefits of clean energy

. This document is available at https://www.epa.gov/statelocalclimate/assessing

- multiple

- benefits

- clean

energy
- resource
- s tates

.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

120 EPA’s AVERT (AVoided Emissions geneRation Tool)

. This tool can be used to estimate the EGU emission impacts of EE/RE. For more information visit: https:// www.epa.gov/avert

.

5.3.1.2 Examples of Existing EGU Project ion Tools T here are specific approaches available that can be used in ways that meet the general principles and key criteria explained in Section 5.3.1

. T he EPA uses the IPM to model future electricity demand and emissions trad ing programs that now dominate the prediction of future

- year emissions from EGUs

. The IPM meets the criteria provided in the EPA resource document listed above

. According to the IPM user ’ s document:

“IPM is a multi

- regional, dynamic, deterministic linear p rogramming model of the U.S. electric power sector. It provides forecasts of least cost capacity expansion, electricity dispatch, and emission control strategies while meeting energy demand and environmental, transmission, dispatch, and reliability constra ints. IPM can be used to evaluate the cost and emissions impacts of proposed policies to limit emissions of SO 2 , NO X , carbon dioxide (CO 2

), mercury (Hg), and HCl from the electric power sector.”

More information on IPM and IPM

- based emissions are available at the Power Sector Modeling EPA website ( https://www.epa.gov/airmarkets/power

- sector

- modeling )

.
Other EGU projection models and tools exist and could be used for estimation of future

- y ear emissions and , in these cases, the states are advised to make sure that the tools meet the criteria laid out in this document because EPA will use these criteria to assess any EGU projection information submitted as part of SIPs

. Mention of specific to ols in this guidance should not be taken as an endorsement or guarantee that such tools will meet the criteria that the EPA will use to evaluate EGU emissions projections

. Alternative tools include the ERTAC Tool, the National Energy Modeling System (NEMS) , the Electric Power Market Model (EPMM) and the M ark et A ll ocation (MARKAL) model . There is also a Northeast

- specific version of MARKAL called NE

- MARKAL

. The subsections below provide additional information and reference links for some of these alternative approaches.

The ERTAC Tool

The ERTAC tool is an open

- source tool developed by the ERTAC group of state and regional associations that benefits from an in

- depth collaboration among a large multi

- state region. More information on this tool is available on t he ERTAC EGU website ( http://www.marama.org/2013

- ertac

- egu
- forecasting

- tool

documentation ), includ ing sample files and documentation.
The ERTAC tool is designed to estimate future EGU activity and emissions using user
- supplied, unit

specific information, CAMD hourly emissions data, and AEO and NERC growth forecasts by fuel and region. T he ERTAC tool outputs hourly future

- year activity, SO 2 emissions, and NO X emissions by key ing off the historical CAMD hourly data from the SIP base year

. For the future

- year planning inventories, the ERTAC results can be aggregated to match the annual or season

- day resolution needed for the regulation being supported (see Section 4.5 )

. For modeled attainment demonstrations (not covered byEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

121 this guidance), the ERTAC h ourly future

- year data outputs may then be used in conjunction with an emissions preprocessor and an air quality model to evaluate the effect of HEDD peri ods as well as other EGU impacts that might be of shorter duration than the modeled period

. Other Approaches
The NEMS model (available at: https://www.eia.gov/forecasts/aeo/info_nems_ar chive.cfm ) was developed by EIA and uses Annual Energy Outlook ( AEO ) projections of energy supply, demand and prices , and it couples with regulatory/SIP and trading assumptions and known future control installations to create future year NO X , SO 2 and heat input estimates

. The EPMM is a private sector EGU model, but some discussion can be found in these reports: http://www.ladco.org/reports/rpo / emissions/eug_growth_methodologies_methods_final_report_pechan.pdf

. The MARKAL model is a data

- driven energy system optimization model geared more towards basic, preliminary analyses of energy policies at EGUs but does not provide plant

- specific detail like IPM . MARKAL is relevant for other sectors and more information is included in Section 5.3.6

. Preventing Double Counting of Emissions between EGUs and Other Categories
To prevent double

- counting of emissions sources between EGUs and other categories , emissions developers should be careful to match the sources of emissions from external models such as IPM with the base year emissions sources

. This helps to ensure that the EGU part of the point source inventory is separated fr om the non

- EGU part based on the facilities included in the future

- year EGU model. In the case of IPM, t he facilities are defined using NEEDS . T he NEEDS records should be compared to the base
year point inventory using the ORIS Plant ID field from both

. In some cases (e.g., co

- generation facilities) , only some of the units at the facilities are included in NEEDS ; therefore, the separation of EGUs from

non
- EGUs should be done at the unit level, not by facility . One resource for this information is also in th e NEI, which contains a field that indicates whether the units are NEEDS units or not.

5.3.2 Non

- EGU Stationary Sources Non

- EGU s tationary s ources include both the point and nonpoint sources, but the methods for projecting them to the future can rely on many of the same sources of information.
Since 2006 (EPA, 2006a), the EPA has been assuming that emissions growth does not track with economic growth for many stationary sources (both point and nonpoint). This “no

- growth” assumption is based on an examination of h istorical emissions and economic data. E mission s (as of 2005) had declined for several years and those reductions could not be directly attributed to specific control
program s despite increasing economic

- based growth factors for many metrics over the same time period

. While the EPA continues to work toward improving the projection approach in its own work, we are still using this no

- growth assumption for many emissions sectors. Of course, where air agencies have better data about the expected growth in emis sions or the possibility of sources reaching their permit limits, that information should be included in developing more refined emissions projections.

The EPA creates and uses data that quantify assumed base year growth (projections), controls, settlement agreements (or consent decrees ) , and other unit and facility

- specific information on non

-Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

122 EGU point and stationary area sources . These are included in the most recent emissions platform Technical Support Document (TSD) available at the Emissions Modeling C learinghouse. The TSD s include the methodologies and background information for projecting sources such as Portland c ement, refineries, oil and gas, industrial/commercial/institutional boilers, residential wood combustion, agricultural sources , fuel sulfur rules, corn and cellulosic ethanol and biodiesel plants, and several other categories

. The data sources include national sources with regional and state

- specific information as well as projection information provided by regional modeling centers and state s and local air agencies.
In addition, the EPA encourages air agencies to consider the latest settlement agreements and consent decrees that are updated periodically by the EPA’s Office of Enforcement and Compliance Assurance (OECA) at: https://www.epa.gov/enforcement/air

- enforcement

.
The additional resources described in Section 5.3.6 are also used by the EPA to develop projections used in i t s modeling platforms. T hese same resources are available to state, local, and tribal agencies to develop their own projection methods for non

- EGU stationary sources.
Finally, f or nonpoint sources, Section 3 of the EIIP projections document provides additional details about proje cting nonpoint

- source . However, several of the references or statements in that document are now out of date, as follows.

 The web sites for SCCs, AP

- 42 emission factors, and more information about area

- source inventories are out of date

. These should be up dated to the same sites as were listed in the point sources section above. Furthermore, this guidance includes more updated information than the EIIP report referenced.

 The ASEM model mentioned in Section 3.2 of the EIIP projection document was not complet ed and is not available.

 The references in Table 3.1

- 2 are out of date and should be updated as follows:

o U

. S

. EPA Emissions trends reports

. These reports can be used to provide the historical trends of emissions sectors based on the National Emissions inve ntory : https://www.epa.gov/air

- trends/

o Multiple Projections System is no longer in use

o California Emission Forecasting System: this system is no longer available

. Interested parties should contact California Air Resources Board for more information on their latest emissions projection approaches.

The tools and data sources described in S ection 5.3.6 below should also be considered for use for projection of point and nonpoint stati onary source emissions.

5.3.3 On

- Road Mobile Sources As described in Section 4.8.3 , f or all states but California, on

- road mobile emissions should be estimated with the latest EPA on

- road mobile model, MOVES, following the EPA’s late st guidance available at https://www3.epa.gov/otaq/models/moves/

. For California, the latest EPA

- approved version of EMFAC sh ould be used.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

123 Emissions preparation with MOVES for projected emissions is mu ch like preparation for a base year

. MOVES includes assumptions about emissions reductions associated with national emissions programs including the effects of national vehicle and fuel standards. Some MOVES inputs, such as meteorology, should be the same as for the base year inventory. Others, such as VMT and vehicle population should be grown/reduced to reflect expected changes in population and activity. MOVES default estimates for future VMT and vehicle population are based on national growth rates and should not be used for SIP inventory purposes because growth rates vary substantially from county to county.
Because of the change to the using the MOVES model and the newer guidance provided on the OTAQ websites, the EIIP projections document is no longer relevant for on

- road mobile sources.

5.3.4 Nonroad Mobile Equipment Section 5 of the EIIP projections document provides details about projecting nonroad mobile sources

. While some information is still valid, s everal of the references or statements in that docum ent are now out of date, as follows.

 The name “ Office of Mo bile Sources ” has changed to “ OTAQ ” and it s primary website is https://www3.epa.gov/otaq/

.

 The EPA’s NONROAD model has been incorporated into the MOVES mo del and should no longer be used for new SIP development

.

 According to a California Air Resources Board website, category

- specific inventory models and methods have replaced most uses of California’s OFFROAD model

. The information on California’s nonroad e missions is available at http://www.arb.ca.gov/msei/categories.htm

. A link to the OFFROAD2007 model is also available from this page to be used for categories not listed on that page.

MOVES includes assumptions about emissions reductions associated with nonroad source national emissions programs

. MOVES also includes assumptions about national growth in nonroad activity and equipment population. Local estimates of future ac tivity and equipment populations should be substituted for the national estimates when possible.

5.3.5 Other Nonroad Mobile Sources Aircraft, l ocomotives, and CMV sources of emissions do not have a specific model designed for projections, and so additional effor t is needed for these three inventory components.
For aircraft emissions, FAA data can be used to estimate growth for aircraft emissions

. The FAA provides summary historical and forecast statistics on passenger demand and aviation activity at U.S. airports

. The summary level forecasts are based on individual airport projections

. The Terminal Area Forecast (TAF) includes forecasts for active airports in the National Plan of Integrated Airport Systems (NPIAS)

. The TAF system can be accessed at https://aspm.faa.gov/main/taf.asp

. The TAF system allows users to create their own forecast scenarios

. The TAF database, which contains a query data application, allows the public to access and print historical and foreca st (up to 20 4 0) aviation activity data by individual airport, state or FAA region

. Air agencies can use this information to adjust their base year emissions based on projected airport activity.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

124 For locomotives and marine vessel emissions, the best source o f data on the impact of national rules from OTAQ is the websites provided for each of the rules and their associated Federal Register notices

. As described for the base year emissions in Section 4.8.5 , the locom otive marine rule information is included at the website https://www3.epa.gov/otaq/nonrdmdl.htm in the subsection “Other Nonroad Reference Material

. ” For CMV sources, Table 20 (from the base year emissions section) provides a good list of individual rules and references

. Since each rule is different, there is no single guidance that can be made about how these should be incorporated

. However, the EPA incorporate s these data into their modeling platforms, and the most recent projection methodologies are documented in the TSDs included with the modeling platforms on the Emissions Modeling Clearinghouse at ht tp s/www.epa.gov/air

- emissions

- modeling

. Additionally for C3 vessel s, emissions data are available from an Emissions Control Area

- International Maritime Organization (ECA

- IMO) project

. These emissions are available at a fine

- grid resolution and are subjec t to various engine and fuel standards in the future. Like base year emissions, air agencies should consider the state versus federal waters when deciding what parts of the ECA

- IMO data to use (see Section 4.8.5.2 ). Growth/cont rol factors have been developed for this C3 CMV inventory , and the EPA is using them for future year C3 CMV inventory development

. The ECA

- IMO rule for C3 CMV can be found
at https://www3.epa.gov/ot aq/oceanvessels.htm

. New approaches are likely to develop over time, so air agency staff should consult the web pages listed here for the latest available information

. The latest EPA modeling platform projection methodology for C3 marine emissions is also available in the latest emissions modeling platform TSD at the Emissions Modeling Clearinghouse mentioned previously

. 5.3.6 Other Projection Resources In addition to sector

- specific resources, there are other sources of information that projection developers c an use for more than a single sector as information to help determine the most applicable growth rates for the modeling region

. These include the Bureau of Labor Statistics “Employment Outlook , ” Census Bureau data, Trade Organizations and individual facili ties, and the Chemical Economics Handbook

. The following paragraphs provide a brief description and additional references for each of the sources of data just listed.
Sources for EPA nonpoint methods

As described in Section 4.8.2 , the EPA develops methods for numerous nonpoint methods

. Each of these methods depends on some surrogate activity

. Many of these activity sources come from USDA, DOE, U.S. Census Bureau, and Department of Labor databases available online

. Appendix B provides a list of nonpoint sectors and associated activity reports and websites

. These data do not include future

- year projections, but may include newer information than were used for estimating the base year information

. As su ch, these data can help with understanding the possible changes in activity (and perhaps emissions) from the date of the underlying base year activity data to the present day

. It should be noted that emissions for 1 year (e.g., 2011) may be estimated using activity data from a prior year (e.g., 2009) because of timing needed for preparing the data does not match with the timing of the release of the underlying data

. When emissions are estimated using data earlier than the emissions baseEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

125 year, it furthe r str engthens the benefit of newer activity data

. Furthermore, these datasets often include historical trends, which could be of use in understanding what may happen in the future.
Since the base year emissions for nonpoint methods are calculated based on direc t activity indicators such as population, fuel consumption, employment, and VMT, projections of these direct activity indicators may also be used to estimate future emissions

. Population is related to sectors such as consumer products, architectural coatin gs, portable fuel containers, and commercial cooking

. VMT also plays a major role in calculation of paved road emissions

. Growth projections for population and fuel consumption are readily available from the U

. S

. Census and the DOE ’s Annual Energy Outlook (see below)

. VMT projections are provided periodically as part of the EPA emissions modeling platforms and may be available in some states from other sources

. Employment projections may also be available in some states and could be used for industrial cate gories where the state believes that employment is an appropriate surrogate for facility activity and therefore emissions growth or retraction.

MARKAL

The MARKAL model is a public sector, data

- driven, energy

- system optimization model

. A user inputs the
str ucture of the energy system to be modeled and data to characterize each of the technologies and resources included in the model run

. MARKAL calculates the least cost set of technologies over time to

s atisfy specific demands, using linear and mixed

- integer linear programming techniques

. Outputs of the model include the technological mix at intervals in the future, energy demand, and estimates of criteria and GHG emissions, among others

. The DOE uses MARKAL for its System for the Analysis of Global Energy Mar kets (SAGE) model. SAGE is used to produce EIA’s annual International Energy Outlook.

The EPA has applied MARKAL for technology and emissions evaluations , which required the development of the EPA MARKAL technology database (EPANMD). This technology

- rich d atabase represents the major sectors in the U.S. energy system, including the commercial, industrial, residential, transportation, and electricity generation sectors. The DOE’s AEO and the NEMS were used to construct the energy supply, demand, and technolo gy characterizations. Data for technologies not represented in the AEO and NEMS were derived from other widely recognized authoritative sources (e.g. , Electric Power Research Institute’s Technical Assessment Guide and DOE’s Office of Transportation Technol ogy’s Quality Metrics report). More information on the EPA ’s use of MARKAL and the EPANMD can be found on the website for “ EPAUS9R

- An Energ y Systems Database for use with the Market Allocation (MARKAL) Model ” and EPA report number NRMRL

- RTP

- 375 (EPA, 2006b)

. Control Strategy Tool (CoST)
The purpose of CoST is to estimate the emission reductions and engineering costs associated with control s trategies applied to point, nonpoint , and mobile sources of air pollutant emissions to support the analyses of air pollu tion policies and regulations. Control strategy results can be exported to CSV files or viewed in a graphical table that supports sortin g, filtering, and plotting. The results can also be merged with the original inventory to create controlled emissions inventories that can be exported toEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

126 files that can be input to the emissions model SMOKE

. CoST allows for user

- supplied control measures d ata, provides tracking of analyses and outputs, and supports built

- in QA

.
The Control Measure dataset focuses on criteria pollutants and their precursors, and it includes primary control efficiencies , co
- pollutant control efficiencies, and control costs

. The data also includes an extensive set of mobile source control measures

. More information on the Control Measure dataset and CoST is available at https://www3.epa.gov/ttn/ecas/cost.htm

. Annual Energ y Outlook
The EIA’s AEO forecast data was a primary input for the final version of EGAS

. However, with EGAS no longer being supported by the EPA , the latest versions of the AEO are the best available source of socioeconomic forecast data for many industria l sectors

. The latest AEO data are available at: http://www.eia.gov/forecasts/aeo/er/index.cfm

.
Census Bureau

The U

. S

. Census Bureau provides data on total employees, total payroll, number of e stablishments, and value of shipments by NAICS code (2 digit

- 6 digit) for specific years

. This database is ideal for examining changes in the number of establishments between the two latest available years and also for historical changes

. Therefore, the actual census data are useful primarily to evaluate emissions changes from the base year to the present (or most recently available year) and comparing to the data included in the AEO. The census data are available at http://www.census.gov/2010census/data/

. In addition, the Census Bureau projects future population, which is available at http://www.census.gov/population/projections/

. This info rmation can be used to help project nonpoint emissions categories that include population as an activity input for the base year emissions.
Trade Organiza tions and I ndividual F acilities
Trade organizations can also be a helpful resource because they often have projections for future

- year growth of their industry and may be aware of pending facility closures or new facility construction

. This resource is most relevant for large industrial sources that usually are included in point source inventories

. In add ition, emissions modelers should consider contacting large sources of emissions in their modeling region for their expectations of emissions growth or reduction

. In many cases, large industries may be willing to provide such information when presented with what will be used if no additional information can be provided

. Additional information may be found in permit applications for future development or controls at individual facilities. Except in the case of permit applications , emissions projections develo pers should be aware of possible conflicts of interest for this source of information . For example, industry groups or facilities may have an incentive to under

- represent future

year emissions in hopes of avoiding additional requirements for reducing emiss ions. However, many industrial representations have been valuable stakeholders who are interested in providing accurate information.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

127 Chemical Economics Handbook
The Chemical Economics Handbook, produced by SRI Consulting (a part of IHS, Inc

. 27 ) , is a series of reports on prices, production and consumption of hundreds of chemical industry products and commodities

. Past and current information on chemical products and commodities is available, and projections of future prices, production and consumption are of ten available

. Reports on specific industries are also available

. Reports at an industry level can often be used to verify the efficacy of future industry modeling results

. Each report is updated every 3 years

. Projections, some up to 5 years from the curr ent day, are often prepared using proprietary methods

. Reports are available by subscription, and can be obtained as hard copy, CD, or at http://www.sriconsulting.com/CEH/Public/index.html

. 

### 5.4 Evaluate and Refine Data for Projections in Inventory R egion For key sectors, emissions projections developers should determine what information will impact the projection results the most, and ensure that the data values reflect conditions or expectation s of the modeling region

. The key information is identified based on a combination of base

- year emissions data and growth and control rates

. An iterative process is helpful to complete this step, as follows:

1. Estimate future

- year emissions by combining the base

- year emissions with the projection information (as described in the EIIP document referenced in Section 5.1 )

. 2. Review future

- year emissions data to identify large sectors of key pollutants (e.g. NO X , SO 2 , PM 2.5 , NH 3 and VOC )

. Emissions summaries by state/SCC or state/NAICS for point sources can be helpful for this step to consolidate the data to review.

3. For the largest future

- year emissions sectors, review the growth and control assumptions, compare among all available data sources, and/or collect additional information to refine the assumptions

. A representative growth rate should be identified from the available data sources and all information known about the sources and sectors

. Stakeholder review of the data can be helpf ul during this step; for example, an industrial facility with large projected emissions may be able to review the data and provide additional information (e.g., expected capacities, fuels or controls) for a more informed future

- year emissions estimate.

4. Add itionally, data developers should also compare the future

- year emissions to base

- year emissions, and if economic

- based growth is used, to identify overall growth rates for industrial sectors and scrutinize excessively high growth rates, especially when ass ociated with significant emissions.

5. Using the new information, repeat step 1 and continue these steps until a satisfactory future

year projection across the entire inventory has been completed.

27 A number of other industry reports appears to be available from the IHS home page from the “Industries” tab. Some of these websites appear to have databases av ailable for a fee, but they have yet not been assessed by EPA for applicability to emissions projections.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

128 Emissions models (e.g., CoST, SMOKE, MOVES, IPM , etc.) provide the capability to create future

- year inventories using base year inventories and projection information

. Emissions modelers will need to convert the projected emissions data into specific formats for input to these models

. Prior to starting this step, dat a developers should determine which emissions model will be used to perform the calculations and make sure that the type of information needed by the model is being collected.


### 5.5 QA for Projected Inventories As mentioned in the previous subsection, final revi ew of the inventories is an iterative process

. During each iteration, a daptations of the methods described in Section 0 can be used for QA of projected emissions inventories. The following list gives examples of some of the way s of the methods for base year inventories can be adapted for projected emissions inventories.

 The same checks used for finding structure errors for base year emissions should be used for ensuring the projected inventories use the correct structures

. The E IS checks are less relevant since projected emissions are more likely to be in a modeling format (since they are used for modeling) than are base year inventories. Even so, data developers should make sure that data structure or formatting problems do not lead to incorrect emissions data being used in planning inventories or modeling.

 Like base year inventories, data codes should be compared to lists of valid codes

. It is just as important to have future

- year SCCs be valid as it is for base year SCCs.

 Ranki ng techniques can be used to identify facilities, units, and processes that have been grown to unrealistic values

. Ranking sources by emissions values can identify any that rise to the top of the list of largest sources without a good reason why

. Ranking t echniques can also be used for projected nonpoint emissions data.

 Inventory comparisons can be made between projected and base year inventories to help make

sure:

o Location information is consistent between base and future year (needed for modeling only)

. o R elease point parameters are consistent between base and future year

. Where controls have been added, one may expect that the release point parameters could change, for example, with higher stacks or lower exit gas temperatures (needed primarily for modelin g).

o Emissions increases and decreases at the facility, unit, and process level are consistent with what is expected.

o Emissions increases and decreases at the county and county/SCC levels are consistent with what is expected

. If certain sectors are being he ld constant (i.e., no better data/approaches are available), then data developers can confirm that these sectors did not change emissions.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

129 

## 6 References Allen, D. J., Pickering, K. E., Pinder, R. W., Henderson, B. H., Appel, K. W., and Prados, A.: Impact of

l ightning

- NO on Eastern United States photochemistry during the summer of 2006 as determined using the CMAQ model, Atmos. Chem. Phys. Discuss., 11, 17699

- 17757, doi:10.5194/acpd

- 11

- 17699

- 2011, 2011.
Appel, K. W., Foley, K. M., Bash, J. O., Pinder, R. W., De nnis, R. L., Allen, D. J., and Pickering, K.: A multi

resolution assessment of the Community Multiscale Air Quality (CMAQ) Model v4.7 wet deposition estimates for 2002

– 2006, Geosci. Model Dev. Discuss., 3, 2315

- 2360, doi:10.5194/gmdd

- 3

- 2315

- 2010, 2010.

EPA , 2006 a

. Regulatory Impact Analyses, 2006 National Ambient Air Quality Standards for Particle

Pollution. U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, October, 2006. Docket # EPA

- HQ

- OAR

- 2001

- 0017, # EPAHQ

- OAR

- 2006

- 0834

. Appendix D: http://www.epa.gov/ttn/ecas/regdata/RIAs/Appendix%20D

-- Inventory.pdf

. EPA, 2006b. Shay, C. L., S. Yeh, J. Decarolis, D. H. Loughlin, C. L. Gage, And E. Wrig ht. EPA U.S. National

MARKAL Database: Database Documentation. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R

- 06/057, 2006.

Fu, J.S., Dong, X., Huang, K., Tong, D., and Zhuang, G.: Model development of dust emission and

heterogeneous chemi stry within the Community Multiscale Air Quality modeling system and its application over East Asia , Atmospheric Chemistry and Physics, 16, 8157

- 8180, 2016.

Reid, S.B., Technical Memorandum, Sonoma Technology, Inc., Preparation of Version 2 of the Wildland

Fire Emissions Inventory for 2011, April 26, 2013.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

A

- 1 

### Appendix A 

## Emissions Inventory System

- Quick Reference How to Create County and Facility NO x 

### and VOC Summaries for Select Counties

Create a summary of NO X and VOC emissions BY SECTOR and COUNTY f or a group of counties 1. Select "Request Reports" from the left hand sidebar on the EIS Gateway.
2. Under the Emissions Summaries heading, select “By Geography

. ”
3. Select Report Type "County by Sector

. "
4. Click the Data Set or Selection bar

. This brings you to a “filter” that a llows you to select an inventory on which to run a report

.

To find a version of the NEI, type “NEI V” in the s earch box under the Data Set or Selection

. Then, click the appropriate row for the year and version of the inventory for your needs.
5. Click on t he Pollutants bar to access the pollutant filter. U se the search box provided and type in “VOC” and select that resulting row for VOC (click on it with the mouse). Repeat this for NO X . Typing both filters at the same time will not work.
6. Because we are look ing at counties, go directly to the C ounty filter

. DO NOT SELECT A STATE FIRST from the State filter (this will select all counties in selected states, even if you then select specific counties in the county filter)

. Use the search box in the County filter to find the counties of interest either by name or State/County FIPS code

. Select the counties of interest by clicking on those rows

. If no counties are selected , all counties will be returned.
7. Last ly , select your Sectors using the S ectors search box

. If no sectors are selected, the report w ill be created with all sectors

. The EIS Sectors are explained in more detail in Section of the 2011 NEI technical documentation.
8. Click the "Request Download" button at the bottom of the screen

. These reports are run by EIS every 15 minutes and are available under the Report Download section o n the left hand sidebar of the Gateway

.

Note: U sing the “Run Report” button will give you a faster response and display the summary on the screen, but may not include all records for your report

. A warning is given at the top of the screen if the “Run Report” result is incomplete.

Create a summary of NO X and VOC emissions BY FACILITY for a group of counties 1. Select "Request Reports" from the left hand sidebar on the EIS Gateway.
2. Under the Emissions Summaries heading, select “By Facility

. ”

For access to the Emissions Inventory System ( EIS )
, refer to https://www.epa.gov/air

- emissions

- inventories/emission

- inventory

- system

- eis

- gateway

.

See also Online EIS training “Reports

– May 2012” at h ttps://www.epa.gov/air

- emissions

- inventories/emission

- inventory

- trainingEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

A

- 2 3. Select Report Type “Facility”

. For more detailed (sub

- facility) data, you may select “Emissions Unit” or “Emissions Process .”
4. Follow Step 4 in the list above.
5. Follow Step 5 in the list above.
6. Follow Step 6 in the list above.
7. Last ly , you may refine your search even more using the optional filters of Facility Types , NAICS , Regulations , or Source Classifications

. If you do not use these filters, all facilities for the selected counties that include NO X and VOC emissions will be returned in the r eport.
8. Follow Step 8 in the list above.Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

B

- 1 

## Appendix B EPA Nonpoint Methods and Associated Activity Data and WebsitesEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

B

- 1 Category Data Type Last Release Date Data Lag

(years) Report Source Link Agriculture Production

- Livestock Livestock Population May 2014

(2012 data) 2 Census of Agriculture USDA http s ://www.agcensus.usda.gov/
Agriculture Production

- Livestock Livestock Population Continuous

Updates USDA NASS Quick Stats USDA https://www.nass.usda.gov/Quick_Stats/
Asphalt Paving

- Cutback Cutback Asphalt Use 2008 Asphalt Usage Survey for the United States and Canada Asphalt Institute http://www.asphaltinstitute.org/ Asphalt Paving

- Cutback VMT 201 4 2 Highway Statistics 20 14 FHWA http://www.fhwa.dot.gov/policyinformation/quickfinddata/qftravel.cfm Asphalt Paving

- Emulsified Emulsified Asphalt Use 2008 Asphalt Usage Survey for the United States and Canada Asphalt Institute http://www.asphaltinstitute.org/ Asphalt Paving

- Emulsified VMT 20 14 2 Highway Statistics 20 14 FHWA http://www.fhwa.dot.gov/policyinformat ion/quickfinddata/qftravel.cfm Aviation Gasoline Distribution

-

Stage 1 AvGas

Consumption Sept 2015

(2014 data) 1.5 Petroleum Supply Annual EIA http://www.eia.gov/petroleum/supply/annual/volume1/

Aviation Gasoline Distribution

-

Stage 2 AvGas

Consumption Sept 2015

(2014 data) 1.5 Petroleum Supply Annual EIA http://www.eia.gov/petroleum/supply/annual/volume1/

Commercial Cooking Population June 2016 (2015 data) 1.5 Population Estimates Program GCT

- T1: Population Estimates U.S. Census Bureau http://www.cens us.gov/popest/

Construction Dust

- NonResidential Construction Value of Construction April 2016 0 Annual Value of Construction Put in Place U.S. Census Bureau http://www.census.gov/construction/c30/c30index.html

Construction Dust

- NonResidential Constru ction Business Patterns 201 4 2 County Business Patterns (e.g., no. establishments, employees) U.S. Census Bureau http://www.census.gov/econ/cbp/index.html

Construction Dust

- NonResidential Construction Construction Costs June 2016 1 mo. Producer Price In dex U.S. Dept. of Labor http://www.bls.gov/ppi/#tables

Construction Dust

- Residential Construction Housing Units (2014 data) 2 Annual Housing Units Authorized by Building Permits CO2010A U.S. Census Bureau https://www.census.gov/popest/data/housing/total s/2014/

Construction Dust

- Residential Construction Housing Starts June 201 6 2 mo. New Privately Owned Housing Units Started for previous quarter U.S. Census Bureau http://www.census.gov/construction/nrc/index.html

Construction Dust

- Residential Const ruction Ratio for 5 or more units May 2016

(2015 data) 5 mo Table 2au. New Privately Owned Housing Units Authorized Unadjusted Units for Regions, Divisions, and States 2009 U.S. Census Bureau http://www.census.gov/construction/bps/stateannual.html

Constru ction Dust

- Residential Construction Types of Foundation (2015 data) Type of Foundation in New One

Family Houses Completed U.S. Census Bureau http://www.census.gov/construction/chars/completed.html (see row for “Foundation”). Construction Dust

- Road Construction VMT 201 4 2 Highway Statistics 20 14 FHWA http://www.fhwa.dot.gov/policyinformation/quickfinddata/qftravel.cfmEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

B

- 2 Category Data Type Last Release Date Data Lag

(years) Report Source Link Construction Dust

- Road Construction Housing Starts June 201 6 2 mo. New Privately Owne d Housing Units Started for previous quarter U .S. Census Bureau http://www.census.gov/construction/nrc/index.html

Fertilizer Application Commercial Fertilizer Usage 2012 Commercial Fertilizers Association of American Plant Food Control Officials http://www.aapfco.org/publications.html#comm (must ord er)

Fuel Combustion

- Commercial Fuel Sales 201 4 2 Fuel Oil and Kerosene Sales EIA http://www.eia.gov/dnav/pet/pet_cons_821use_dcu_nus_a.htm
Fuel Combustion

- Commercial Business Patterns 201 4 2 County Business Patterns (e.g., no. establishments, employ ees) U.S. Census Bureau http://www.census.gov/econ/cbp/index.html

Fuel Combustion

- Commercial Gov't Payrolls 2016 (2012 data) 4 Census of Governments U.S. Census Bureau https://www.census.gov/govs/cog/

Fuel Combustion

- Commercial Fuel Consumption 201 4 2 State Energy Data System (SEDS) EIA http://www.eia.gov/state/seds/
Fuel Combustion

- Industrial Fuel Sales 201 4 2 Fuel Oil and Kerosene Sales EIA http://www.eia.gov/dnav/pet/pet_cons_821use_dcu_nus_a.htm
Fuel Combustion

- Industrial Business Patterns 201 4 2 County Business Patterns (e.g., no. establishments, employees) U.S. Census Bureau http://www.census.gov/econ/cbp/index.html

Fuel Combustion

- Industrial Energy Consumption March 2012

(2010 data) 3.5 Energy consumption as a fuel, by industry and reg ion EIA http://www.eia.gov/consumption/manufacturing/

Fuel Combustion

- Industrial Fuel Consumption 201 4 2 State Energy Data System (SEDS) EIA http://www.eia.gov/state/seds/
Gasoline Distribution

- PFCs
Gasoline Distribution

- Stage 1 Business Pat terns 201 4 2 County Business Patterns (e.g., no. establishments, employees) U.S. Census Bureau http://www.census.gov/econ/cbp/index.html

Gasoline Distribution

- Stage 1 Fuel Consumption Sept 2015

(2014 data) 1.5 Petroleum Supply Annual EIA http://www.eia. gov/petroleum/supply/annual/volume1/

Gasoline Distribution

- Stage 2
Industrial Fuel Combustion Business Patterns 201 4 2 County Business Patterns (e.g., no. establishments, employees) U.S. Census Bureau http://www.census.gov/econ/cbp/index.html
In dustrial Fuel Combustion Fuel Sales 2011 2 Fuel Oil and Kerosene Sales EIA http://www.eia.gov/dnav/pet/pet_cons_821use_dcu_nus_a.htm

Industrial Fuel Combustion Energy Consumption June 2009 3.5 2006 Manufacturing Energy Consumption Survey EIA http://www.ei a.gov/emeu/mecs/mecs2006/2006tables.html

Industrial Fuel Combustion Fuel Consumption 201 4 2 State Energy Data System (SEDS) EIA http://www.eia.gov/state/seds/
Open Burning

- Household Waste Solid Waste Generation 2011 2 Municipal Solid Waste in the Unite d States: 2009 Facts and Figures EPA http://www.epa.gov/epawaste/nonhaz/municipal/msw99.htmEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

B

- 3 Category Data Type Last Release Date Data Lag

(years) Report Source Link Open Burning

- Household Waste Population June 2016 (2015 data) 1.5 Population Estimates Program GCT

- T1: Population Estimates U.S. Census Bureau http://www.census. gov/popest/
Open Burning

- Land Clearing Business Patterns 201 4 2 County Business Patterns (e.g., no. establishments, employees) U.S. Census Bureau http://www.census.gov/econ/cbp/index.html
Open Burning

- Land Clearing Housing Units (2014 data) 2 Annual Housing Units Authorized by Building Permits CO2010A U.S. Census Bureau https://www.census.gov/popest/data/housing/totals/2014/

Open Burning

- Land Clearing Value of Construction 201 6 0 Annual Value of Construction Put in Place U.S. Census Bureau https:// www.census.gov/construction/c30/c30index.html

Open Burning

- Land Clearing Housing Starts June 201 6 2 mo. New Privately Owne d Housing Units Started for previous quarter U.S. Census Bureau http://www.census.gov/construction/nrc/index.html

Open Burning

- L and Clearing Ratio for 5 or more units May 2016

(2015 data) 5 mo Table 2au. New Privately Owned Housing Units Authorized Unadjusted Units for Regions, Divisions, and States 2009 U.S. Census Bureau http://www.census.gov/construction/bps/stateannual.html

Op en Burning

- Leaves and Brush Solid Waste Generation 201 3 3 Municipal Solid Waste in the United States: 20 13 Facts and Figures EPA https://www.epa.gov/smm/advancing

- sustainable

- materials

management

- facts

- and

- figures

- report Open Burning

- Leaves and Brush Population June 2016 (2015 data) 1.5 Population Estimates Program GCT

- T1: Population Estimates U.S. Census Bureau http://www.census.gov/popest/

Paved Road Dust VMT 20 14 2 Highway Statistics 20 14 FHWA http://www.fhwa.dot.gov/policyinformation/quickfinddat a/qftravel.cfm

Publicly Owned Treatment Works Nationwide Flow rate January

2016 4 Clean Watersheds Needs Survey 2012 Data and Reports, Detail

Report EPA https://www.epa.gov/cwns/clean

- watersheds

- needs

- survey
- cwns
2012

- report

- and

- data#access

Publicly Owne d Treatment Works Population June 2016 (2015 data) 1.5 Population Estimates Program GCT

- T1: Population Estimates U.S. Census Bureau http://www.census.gov/popest/

Residential Coal Coal Distribution Dec 2016

(2014 data) 2 Annual Coal Distribution EIA http:/ /www.eia.gov/cneaf/coal/page/coaldistrib/a_distributions.html

Residential Coal Fuel Consumption 201 4 2 State Energy Data System (SEDS) EIA http://www.eia.gov/state/seds/

Residential Coal House Heating Fuel Type 2014 2 House Heating Fuel (online report fr om “Advanced Search”) U.S. Census Bureau http://factfinder.census.gov/faces/nav/jsf/pages/searchresults.xhtml?

refresh=t#none (Enter: “heating fuel” in search field)
Residential Distillate Fuel Fuel Consumption 201 4 2 State Energy Data System (SEDS) EIA ht tp://www.eia.gov/state/seds/

Residential Distillate Fuel House Heating Fuel Type 2014 2 House Heating Fuel (online report from “Advanced Search”) U.S. Census Bureau http://factfinder.census.gov/faces/nav/jsf/pages/searchresults.xhtml?

refresh=t#none (Enter : “heating fuel” in search field)Emissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT

B

- 4 Category Data Type Last Release Date Data Lag

(years) Report Source Link Residential Kerosene Fuel Consumption 201 4 2 State Energy Data System (SEDS) EIA http://www.eia.gov/state/seds/

Residential Kerosene House Heating Fuel Type 2014 2 House Heating Fuel (online report from “Advanced Search” ) U.S. Census Bureau http://factfinder.census.gov/faces/nav/jsf/pages/searchresults.xhtml?

refresh=t#none (Enter: “heating fuel” in search field)
Resid ential LPG Fuel Consumption 201 4 2 State Energy Data System (SEDS) EIA http://www.eia.gov/state/seds/

Residential LPG House Heating Fuel Type 2014 2 House Heating Fuel (online report from “Advanced Search”) U.S. Census Bureau http://factfinder.census.gov/faces/nav/jsf/pages/searchresults.xhtml?

refresh=t#none (Enter: “heating fuel” in search field)
Residential Natural Gas Fuel Consumption 201 4 2 State E nergy Data System (SEDS) EIA http://www.eia.gov/state/seds/

Residential Natural Gas House Heating Fuel Type 2014 2 House Heating Fuel (online report from “Advanced Search”) U.S. Census Bureau http://factfinder.census.gov/faces/nav/jsf/pages/searchresults.xhtml?

refresh=t#none (Enter: “heating fuel” in search field) Residential Wood Timber Output 201 2 4 Timber Products Output Reports USDA http://srsfia2. fs.fed.us/php/tpo_2009/tpo_rpa_int1.php

Residential Wood House Heating Fuel Type 2014 2 House Heating Fuel (online report from “Advanced Search”) U.S. Census Bureau http://factfinder.census.gov/faces/nav/jsf/pages/searchresults.xhtml?

refresh=t#none (Enter: “heating fuel” in search field)

Residential Wood Heating Equipment Type 2013 3 American Housing Survey for the United States: 20 13 Summary Tables , T able C

- 03

- AO : Heating, Air Conditioning, and Appliances

– All Occupied Units U.S. Census Bureau http://www.census.gov/programs

- surveys/ahs/data.html

Residential Wood Metropolitan Characteristics 201 3 3 American Housing Survey Metropolitan Data U.S. Census Bureau http://www.census.gov/programs

- surveys/ahs/data/2013/ahs

- 2013

-

summary
- tables/metropolitan

- summary
- tables

--- ahs

- 2013.html Solvent Usage

- Other Population June 2016 (2015 data) 1.5 Population Estimates Program GCT

- T1: Population Estimates U.S. Cens us Bureau http://www.census.gov/popest/
Solvent Usage

- Other Business Patterns 201 4 2 County Business Patterns (e.g., no. establishments, employees) U.S. Census Bureau http://www.census.gov/econ/cbp/index.html
Solvent Usage

- Surface Coatings Population June 2016 (2015 data) 1.5 Population Estimates Program GCT

- T1: Population Estimates U.S. Census Bureau http://www.census.gov/popest/

Solvent Usage

- Surface Coatings Business Patterns 201 4 2 County Business Patterns (e.g., no. establishments, employees) U.S. Census Bureau http://www.census.gov/econ/cbp/index.html Unpaved Road Dust VMT 20 14 2 Highway Statistics 20 14 FHWA http://www.fhwa.dot.gov/policyinformation/quickfinddata/qftravel.cfmEmissions Inventory Guidance for Ozone & PM NAAQS Implementation and Regional Haze Regulations 9/29/2016 DRAFT