MARYLAND DEPARTMENT OF THE ENVIRONMENT

AIR AND RADIATION MANAGEMENT ADMINISTRATION

State Implementation Plan 

Projection Year SIP Emissions 

Inventory Methodologies 

Prepared for: 

U.S. Environmental Protection Agency 

Prepared By: 

Maryland Department of the Environment 
Maryland Department of the Environment 

Projection Year Emissions Inventory Methodologies 

 Maryland Department of the Environment 

Air and Radiation Management Administration 

1800 Washington Boulevard, Suite 730 

Baltimore, Maryland 21230 

Phone 410.537.3240 • Fax 410.631.3202 
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Table of Contents 

1.1 ON-ROAD MOBILE SOURCES ...........................................................................3

1.2 NONROAD MOBILE SOURCES..........................................................................3

1.3 POINT SOURCES...................................................................................................4

1.4 QUASI-POINT SOURCES.....................................................................................4

1.5 AREA SOURCES ....................................................................................................4
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1.0 PROJECTION YEAR INVENTORY 

DEVELOPMENT 

This section describes the proposed approach to estimating future year emissions for the State of 

Maryland nonattainment areas for the purposes of meeting maintenance plan requirements. 

In preparing the projection year inventories, the approach should address two components: (1) 

estimating expected changes in emissions generating activity between the base year (2002) and the 

projection years; and (2) accounting for changes in emission rates by source category resulting 

from air pollution regulations or the replacement of equipment with new, lower emitting 

technologies. For the first component, the best way for estimating activity changes is to pick an 

indicator for each source category that has available projections data and provides as direct as 

possible a link to emissions generating activity. 

Possible sources of projections data, in order of preference, are: (1) State of Maryland 

economic/population projections at the State, sub-State level, or facility level, (2) recent regional 

economic projections, or (3) State-level activity projections from EPA’s Economic Growth 

Analysis System (EGAS). EGAS provides growth factors for the years of interest, which are 

linked to standard emission inventory Source Classification Codes (SCCs). 

Modeling of control effects will focus on the source categories whose emission rates are expected 

to change between 2002 and 2009 or 2014. These source categories include on-road mobile 

sources, nonroad mobile sources, and residential wood combustion. 

1.1 ON-ROAD MOBILE SOURCES 

On-road mobile source emission projections to 2009 and 2014 will be made using 

MOBILE6.2 emission factors and projections of VMT by vehicle type, roadway functional 

classification, and associated speed by the BRTB and their staff, BMC and MDE. 

BRTB and BMC will supply MDE with input data for projection years. The projection year 

emission estimates will take into account any fuels strategies that were adopted or planned for the 

area, and any changes in fuel specifications that change by month/season in order to calculate 

winter period and annual average emissions. 

1.2 NONROAD MOBILE SOURCES 

The nonroad mobile source sectors for which emission projections will be needed include aircraft, 

locomotives, marine vessels, and EPA NONROAD model categories. Aircraft emission 

projections will use local airport landing-takeoff projections with adjustments (if needed) to 

aircraft emission factors to account for the effects of emission standards, or technology changes. 

Similar methods are planned for locomotives emission projections. For NONROAD model 

categories, emission projections will be based on running the current version of EPA’s 

NONROAD model for the projection years with Maryland-specific inputs used in the base year 

inventory development. NONROAD model inputs are listed below. 
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Parameters:

2002 2008 

Uncontrolled

2008 

Controlled

2009 

Uncontrolled

2009 

Controlled

BNAA-MD BNAA-MD BNAA-MD BNAA-MD BNAA-MD

Min. Temp. 65.55 65.55 65.55 65.55 65.55 

Max. Temp. 87.6 87.6 87.6 87.6 87.6 

Avg. Temp. 76.8 76.8 76.8 76.8 76.8 

RVP 6.6 6.6 6.6 6.6 6.6 

O2 % 2 2 2 2 2 

Gas Sulfur % 0.0162 0.0162 0.003 0.0162 0.003 

LPG/CNG Sulfur % 0.003 0.003 0.003 0.003 0.003 

Diesel Sulfur% 0.2283 0.2283 0.0348 0.2283 0.0348 

Marine Diesel Sulfur % 0.2638 0.2638 0.0408 0.2638 0.0408 

Stage II Control % 0 0 0 0 0 

1.3 POINT SOURCES 

Point sources will include those with allowable emissions of 50 or more tons per year of CO. In 

addition to the actual emissions reported for each facility, allowable or potential to emit emissions 

for point sources will be included. These allowable emissions are important to consider in 

projected emission inventories, especially where they are much different than actual emissions. 

Actual emissions will be forecast to the projection years using EGAS growth surrogates. 

1.4 QUASI-POINT SOURCES 

Quasi-point sources will include all emissions at the facility regardless of whether they are 

classified as point, area, nonroad, or mobile source emissions. These emissions are actual 

emissions reported for the facilities. Actual emissions will be forecast to the projection years 

using surrogates specific to each quasi-point source. The growth factor indicators and their 

sources are listed below by facility: 

Quasi-Point Source Surrogate Growth Indicator 

Baltimore Washington International Airport (BWI) 

 Aircraft LTOs FAA Aircraft Operations Forecasts 

 Mobile Source Emissions FAA Enplanement Forecasts 

Aberdeen Proving Grounds BRAC Population Estimates 

1.5 AREA SOURCES 

Area source projections are typically made using local information and/or growth surrogates. The 

effects of any control measures to be implemented between the base and projection years are then 

applied (e.g., using an estimate of control efficiency, rule penetration, and rule effectiveness). 

Projection methods are described below. 

For all sources except residential wood combustion and agricultural burning (including orchard 

tear-out burning), emissions will be projected by multiplying the base year emission rates by the 
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surrogate activity indicator growth factors. Details on the woodstove projection method are 

described in Section D. Pechan will work with SCAPCA, the Washington State University 

Cooperative Extension Service and other local agricultural contacts to estimate future agricultural 

burning activity levels. Surrogate activity indicators for each area source category are shown in the 

table below. 

 Source Category Surrogate Growth Indicator

 Petroleum Distribution Losses 

Aircraft Refueling EMP 

Petroleum Vessel Unloading EMP 

Stage II Refueling GAS 

Tank Breathing GAS 

Tank Transit GAS 

Tank Unloading GAS 

Portable Fuel Containers POP 

 Catastrophic/Accidental Releases 

Oil Spills NA 

Soil Remediation NA 

 Fire Sources 

Automobile Fires POP 

Forest Fires NA 

Slash Burning NA 

Prescribed Burning NA 

Structure Fires POP 

 Stationary Area 

Dry Cleaners POP 

Architectural Surface Coatings - Water Based POP 

Architectural Surface Coatings - Solvent Based POP 

Cold Cleaning/Degreasing EMP 

Auto Refinishing EMP 

Traffic Paints - Total POP 

Commercial - Consumer Solvents POP 

Emulsified Asphalt POP 

Graphic Arts POP 

Industrial Surface Coatings EMP 

Industrial Adhesives EMP 

Pesticides NA 

 Small Stationary Source Fuel Combustion 

Commercial/Institutional Coal Combustion EMP 

Commercial/Institutional Kerosene Combustion EMP 

Commercial/Institutional Distillate Oil Combustion EMP 

Commercial/Institutional Residual Oil Combustion EMP 

Commercial/Institutional LPG Combustion EMP 

Commercial/Institutional Natural Gas Combustion EMP 

Residential Coal Combustion NA 

Residential Kerosene Combustion HSE 

Residential Distillate Oil Combustion HSE 
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 Source Category Surrogate Growth Indicator

Residential Natural Gas Combustion HSE 

Residential LPG Combustion HSE 

Residential Wood Combustion POP 

Industrial Distillate Oil Combustion EMP 

Industrial Residual Oil Combustion EMP 

 Bioprocess Emission Sources 

Bakeries POP 

Brewpubs POP 

Wineries POP 

Distilleries NA 

 Miscellaneous Area Sources 

Agricultural Land Preparation NA 

Construction – Residential POP 

Construction – Heavy POP 

Construction – Road POP 

 Solid Waste Treatment, Disposal, and Recovery 

Incinerators NA 

Open Burning – Land Clearing Debris POP 

Open Burning – Residential Municipal Solid Waste POP 

Open Burning – Residential Brush Debris POP 

Open Burning – Residential Leaf Debris POP 

Landfills POP 

POTWs HSE 

 Nonroad Sources (Outside NONROAD Model) 

Military Aircraft EGAS 

General Aviation Aircraft EGAS 

Air Taxi Aviation Aircraft EGAS 

Marine Vessels EMP 

Railroad Engines EMP 

Future year emission projections for RWC will incorporate expected changes in activity and 

emission factors that account for the anticipated mix of wood stove types, and their expected CO 

emission rates for each projection year. The technology mixes in 2010 and 2015 are especially 

important because wood stoves have had to meet a set of increasingly more stringent new source 

performance standards. An important assumption in estimating the technology mix in future years 

is the expected lifetime/replacement rate for wood stoves. The faster the replacement rate, the 

lower the average emission rate in future years for the wood stove population. Pechan will use 

contacts with government agencies and industry to develop an estimate of lifetime/replacement. 

RWC emission estimates for the projection years will also account for any local programs to 

curtail wood stove/fireplace use, etc.