Appendix B1 (Washington DC-MD-VA Redesignation Request & Maintenance Plan, 

May 22, 2013) Page 1

Appendix B1

Technical Support Document 

for the

Development of Nonroad Mobile 

(Except Marine, Airport, and Railroad) 

Emissions inventories for 2025

(Washington, DC-MD-VA PM2.5 Nonattainment Area)
Appendix B1 (Washington DC-MD-VA Redesignation Request & Maintenance Plan, 

May 22, 2013) Page 2

Table of Contents

1.0 INTRODUCTION..............................................................................................3

1.1 GEOGRAPHIC RESOLUTION......................................................................................................3

1.2 POLLUTANTS ..................................................................................................................................4

1.3 DESCRIPTION OF NMIM MODEL VERSION USED FOR 2025 INVENTORY 

DEVELOPMENT..............................................................................................................................4

1.4 DEESCRIPTION OF NMIM MODEL INPUTS USED FOR 2025 INVENTORY 

DEVELOPMENT..............................................................................................................................4

1.5 EMISSIONS SUMMARY.................................................................................................................5
Appendix B1 (Washington DC-MD-VA Redesignation Request & Maintenance Plan, 

May 22, 2013) Page 3

1.0 INTRODUCTION

This technical support document (TSD) describes in detail the input data and their sources and 

the method used to develop projected emissions for nonroad mobile sources (except for 

marine vessels, airport, and railroad) for 2025 for PM2.5-Pri, NOx, and SO2 for the 

Washington, DC-MD-VA PM2.5 nonattainment area counties and cities. Emissions for 2007, 

2017, and 2025 (Virginia only) were estimated by MARAMA and the details of the 

development of these emissions are described in the MARAMA TSDs listed in Appendix A1. 

Nonroad Mobile Sources include equipments such as forklifts, lawn and garden equipments, 

portable generators, marine vessels, airplanes, locomotives, etc. Except for marine vessels, 

airplanes, and railroad locomotives (MAR), the inventory for all other nonroad mobile 

sources was developed using the most current version of USEPA’s NONROAD model as 

embedded in the National Mobile Inventory Model (NMIM). The NONROAD model does 

not include emissions from MAR sources. Emissions from these sources for 2025 were 

estimated by MARAMA and the details of the development of these emissions are described 

in the MARAMA TSD titled “Technical Support Document for the Development of the 2025 

Emission Inventory for PM Nonattainment Counties in the MANE-VU Region Version 3.3 

Rev.2. January 23, 2012” listed in Appendix A1. 

1.1 GEOGRAPHIC RESOLUTION

The inventory was developed at the county/city level and emissions summaries by jurisdiction 

for all counties and cities in the Washignton, DC-MD-VA PM2.5 nonattainment area (1997 

annual PM2.5 NAAQS) are provided. 

List of Washington, DC-MD-VA PM2.5 Nonattainment Areas Counties & Cities

State FIPS Code County/City

DC 11001 Washington

MD 24017 Charles

MD 24021 Frederick

MD 24031 Montgomery

MD 24033 Prince George

VA 51013 Arlington

VA 51059 Fairfax

VA 51107 Loudoun

VA 51153 Prince William

VA 51510 Alexandria

VA 51600 Fairfax City

VA 51610 Falls Church City

VA 51683 Manassas City

VA 51685 Manassas Park City
Appendix B1 (Washington DC-MD-VA Redesignation Request & Maintenance Plan, 

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1.2 POLLUTANTS

The inventory includes emissions for directly emitted PM2.5 (PM2.5-Pri), oxides of nitrogen 

(NOx), and sulfur dioxide (SO2). 

1.3 DESCRIPTION OF NMIM MODEL VERSION USED FOR 2025 

INVENTORY DEVELOPMENT

MWCOG used the same NMIM version as the one used by MARAMA for developing the 

2017 and 2025 inventories. A description of the NMIM version is provided in the MARAMA 

TSD titled “Technical Support Document for the Development of the 2017 / 2020 Emission 

Inventories for Regional Air Quality Modeling in the Northeast / Mid-Atlantic Region 

Version 3.3, January 23, 2012”. MWCOG used the NMIM2008 software (version 

NMIM20090504), the revised NMIM County Database (NCD20090910MARAMA), and 

NONROAD2008a (July 2009 version). A detailed description of the NMIM model is 

available at the EPA web-site (http://www.epa.gov/otaq/nmim.htm).

1.4 DEESCRIPTION OF NMIM MODEL INPUTS USED FOR 2025 

INVENTORY DEVELOPMENT

MARAMA developed the version 3.3 (most current version till completion of this PM2.5 

maintenance plan) of the 2025 NMIM emission inventory for Virginia for PM2.5 maintenance 

plan purposes, but it did not do so for the District of Columbia and Maryland. However, 

MARAMA developed the version 3.3 of the NMIM inventory for the two jurisdictions for 

2017 for the regional photochemical modeling purposes (See Appendix A for MARAMA 

TSD for the development of the 2017 NMIM analysis). Therefore, MWCOG developed the 

2025 NMIM analysis for the District of Columbia and Maryland using the inputs used by 

MARAMA for developing the above mentioned version 3.3 of the 2017 modeling inventory 

for the two jurisdictions. Meteorology and allocation files used by MARAMA for the 2017 

analysis for the above two jurisdictions were applied to the 2025 anlysis as well. Fuel 

charachteristcs used by MARAMA for the 2017 analysis for the two jurisdictions were 

NMIM defaults for 2017 and are the same as the NMIM defaults for 2025. Therefore, the 

same fuel charachteristics were also used for the 2025 analysis. 

MWCOG replicated the 2025 NMIM emissions for Virignia using MARAMA’s inputs. These 

inputs are described in detail in the MARAMA TSD for the development of 2025 emission 

inventories listed in Appendix A1. 
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1.5 EMISSIONS SUMMARY

2025 Nonroad Emissions (Excluding MAR Sources) Summary by Jurisdiction

County/City NOx SO2 PM2.5-Pri

Washington, DC 992.3 3.0 72.3

Charles 365.7 1.1 28.3

Frederick 502.4 1.8 72.0

Montgomery 1400.6 5.2 241.9

Prince George 1130.6 3.9 150.5

Arlington 413.6 1.2 35.1

Fairfax 1469.9 6.5 249.7

Loudoun 928.8 3.6 139.5

Prince William 623.5 2.3 84.4

Alexandria 80.3 0.4 14.6

Fairfax City 33.8 0.2 7.6

Falls Church City 18.3 0.1 4.8

Manassas City 30.9 0.2 3.6

Manassas Park City 17.9 0.1 4.6

State Total

Washington, DC 992.3 3.0 72.3

Maryland 3399.3 12.0 492.8

Virginia 3617.0 14.6 543.8

Region Total 8008.6 29.7 1108.9