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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION III

1650 Arch Street

Philadelphia, Pennsylvania 19103

 

SUBJECT: Technical Support Document (TSD) - Adequacy Findings for the Motor Vehicle 

Emissions Budgets in the 1997 Fine Particulate Matter (PM2.5) National Ambient 

Air Quality Standard (NAAQS) Maintenance Plan for the Metropolitan 

Washington, D.C. 1997 PM2.5 Nonattainment Area (DC-MD-VA).

FROM: Gregory Becoat /s/ 2/11/14

Office of Air Program Planning (3AP30)

Asrah Khadr /s/ 2/11/14

Office of Air Program Planning (3AP30)

TO: Administrative Record for the Adequacy Findings for the Motor Vehicle 

Emissions Budgets in the 1997 Fine Particulate Matter (PM2.5) National Ambient 

Air Quality Standard (NAAQS) Maintenance Plan for the Metropolitan 

Washington, D.C. 1997 PM2.5 Nonattainment Area (DC-MD-VA).

THRU: Cristina Fernandez, Associate Director /s/ 2/11/14

Office of Air Program Planning (3AP30)

I. Background

On January 5, 2005 (70 FR 944, 1014), the Environmental Protection Agency (EPA) published 

air quality area designations for the 1997 PM2.5 NAAQS. In that rulemaking action, EPA 

designated the Metropolitan Washington, D.C. Area as nonattainment for the 1997 annual PM2.5

standard. The Metropolitan Washington, D.C. Area includes the entire District of Columbia; 

Arlington, Fairfax, Loudoun, and Prince William Counties and the cities of Alexandria, Fairfax, 

Falls Church, Manassas, and Manassas Park in Virginia and Charles, Frederick, Montgomery, 

and Prince George’s Counties in Maryland. See 40 CFR 81.309, 81.321, and 81.347. Additional 

background information about the Metropolitan Washington, D.C. 1997 PM2.5 Nonattainment 

Area (DC-MD-VA) (hereafter, the Washington Area) is available in the notice of proposed 

rulemaking (NPR) in this docket.

By transmittal letters dated as shown in Table 1, the State of Maryland, the Commonwealth of 

Virginia, and the District of Columbia each formally submitted as a State Implementation Plan 
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(SIP) revision a combined 1997 PM2.5 NAAQS Maintenance Plan (hereafter the Maintenance 

Plan) that included motor vehicle emissions budgets (MVEBs) for PM2.5 and nitrogen oxides 

(NOx) for the Washington Area. 

 Table 1. State SIP Submission Dates 

Jurisdiction Submittal Date

Maryland July 10, 2013

Virginia June 3, 2013

District of 

Columbia 

June 3, 2013

II. Transportation Conformity Requirements

Transportation conformity is required under section 176(c) of the Clean Air Act (CAA) to ensure 

that federally supported highway, transit projects, and other activities are consistent with 

(conform to) the purpose of the State Implementation Plan (SIP). The CAA requires federal 

actions in nonattainment and maintenance areas to “conform to” the goals of SIP. This means 

that such actions will not cause or contribute to violations of a NAAQS; worsen the severity of 

an existing violation; or delay timely attainment of any NAAQS or any interim milestone. 

Actions involving Federal Highway Administration (FHWA) or Federal Transit Administration 

(FTA) funding or approval are subject to the Transportation Conformity Rule (40 CFR part 93, 

subpart A). Under this rule, metropolitan planning organizations (MPOs) in nonattainment and 

maintenance areas coordinate with state air quality and transportation agencies, EPA, FHWA, 

and FTA to demonstrate that their metropolitan transportation plans and transportation 

improvement plans (TIPs) conform to applicable SIPs. This is typically determined by showing 

that estimated emissions from existing and planned highway and transit systems are less than or 

equal to the MVEBs contained in a SIP.

For MVEBs to be approvable, they must meet, at a minimum, EPA’s adequacy criteria found at 

40 CFR 93.118(e)(4). EPA’s adequacy criteria are: (1) the submitted control strategy 

implementation plan was endorsed by the Governor or designee and was subject to a State public 

hearing; (2) consultation among Federal, State, and local agencies occurred; full implementation 

plan documentation was provided to EPA; and EPA's stated concerns, if any, were addressed 

before the control strategy implementation plan was submitted; (3) the MVEBs are clearly 

identified and precisely quantified; (4) the MVEBs, when considered together with all other 

emissions sources, are consistent with applicable requirements for maintenance; (5) the MVEBs 

are consistent with and clearly related to the emissions inventory and the control measures in the 

submitted control strategy implementation plan; and (6) revisions to previously submitted 

maintenance plans explain and document any changes to previously submitted budgets and 

control measures; impacts on point and area source emissions; any changes to established safety 

margins; and reasons for the changes (including the basis for any changes related to emission 
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factors or estimates of vehicle miles traveled).

III. Review of the Submitted Modeling Utilizing the Motor Vehicle Emission Simulator 

(MOVES2010)

To run the MOVES2010 model, a run specification (hereafter referred to as “RunSpec”) must be 

created so the appropriate parameters are selected for the modeling run. The RunSpecs were 

reviewed against the following EPA document: Technical Guidance on the use of MOVES2010 

for Emission Inventory Preparation in State Implementation Plans and Transportation 

Conformity. This guidance document provides guidance on the use of the MOVES model to 

develop inventories for SIPs as well as analysis of emissions for transportation conformity 

determinations. 

MVEBs were submitted for the years 2017 and 2025 for the 1997 PM2.5 NAAQS which are 

consistent with the rest of the emissions inventory in the Washington Area Maintenance Plan. 

The ten counties/cities which comprise the Washington Area were modeled using an individual 

RunSpec for each county/city. The Virginia counties/cities include Alexandria City, Arlington 

County, Fairfax County, and Loudon County. The Maryland counties include Charles County,

Frederick County, Montgomery County, Prince George’s County, and Prince William County. 

The District of Columbia was modeled as its own individual area. The submitted RunSpecs, 

input files and output files were reviewed and found to have followed the applicable EPA 

guidance provided in the Technical Guidance on the use of MOVES2010 for Emission Inventory 

Preparation in State Implementation Plans and Transportation Conformity. Table 2 presents the 

RunSpec parameters that were reviewed and each parameter’s respective component in the

submittal.

Table 2. RunSpec Reviews for the 1997 PM2.5 NAAQS for Years 2017 and 2025 for the 

Washington Area 

Domain/Scale County scale was selected. County scale also accommodates 

independent cities, which were present in these modeling 

runs. Selection of county scale is acceptable for this air 

quality analysis.

Calculation Type Inventory was selected which is acceptable for this analysis.

Time Aggregation Level Hourly time aggregation was selected. Selection of hourly 

time aggregation level is acceptable for this analysis.

Calendar Year Of Evaluation The appropriate calendar years were selected for each 

RunSpec; each RunSpec had 2017 or 2025 as the selected 

calendar year. MOVES2010b can model years 1990 and 

1999-2050.

Month of Evaluation All 12 months were selected for evaluation.

Type of Day of Evaluation Weekdays and weekends were selected, which is appropriate 

for the evaluation of pollutant emissions related to PM2.5. 

Hours of Evaluation Starting and ending hours create a whole day (from 0-24 

hours).

Geographic Bounds The appropriate county/city were selected for each Runspec. 
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The following counties/cities were selected: Alexandria 

City, Arlington County, Fairfax County, Loudon County, 

Charles County, Frederick County, Montgomery County, 

Prince George’s County, Prince William County, and the 

District of Columbia. 

Vehicles/Equipment: OnRoad Vehicle Equipment Appropriate combinations of fuels and source use types were 

made.

Road Type Selection included all necessary road types. 

Pollutants and Processes NOx, sulfur dioxide (SO2) and all forms of primary PM2.5 

were selected. Only emissions of NOx and PM2.5 are 

necessary for the analysis of PM2.5 emissions. 

On-Road Retrofits N/A

ROP N/A

Output Database/Unit 

Selection

Mass units selected to be U.S. Tons; energy units selected to 

be Joules; distance units selected to be miles. 

Output Emission Detail in 

Emission Rate Calculations

Emission detail was selected via user preference. The output 

emissions detail does not affect the results of the modeling 

runs, therefore user preference is acceptable. 

Advanced Performance 

Features 

N/A

IV. Administrative Requirements for Making Adequacy Findings 

EPA followed the process for determining the adequacy of the submitted SIP MVEBs in 

accordance with the procedures listed in the January 2008 Conformity Regulations contained in 

40 CFR part 93, 118(f) “Adequacy review process for implementation plan submissions.” EPA 

will be issuing a notice of proposed rulemaking (NPR) for a 30-day public comment period 

soliciting public comment for the approvability of the State of Maryland’s, the Commonwealth 

of Virginia’s, and the District of Columbia’s SIP submission. The NPR also proposes approval 

of the MVEBs for milestone year 2017 and the out-year 2025 for the Washington Area for PM2.5 

and NOx. 

On February 5, 2014, notices were posted on EPA’s web site located at: 

http://www.epa.gov/otaq/stateresources/transconf/currsips.htm, for the purpose of opening EPA’s 

30-day public comment period on the adequacy/approvability of the budgets in the Washington 

Area Maintenance Plan. The notices were posted separately for the State of Maryland, the 

Commonwealth of Virginia, and the District of Columbia. The purpose of the notices is to 

inform the public of the availability of the Washington Area Maintenance Plan on its own 

website. EPA’s website notice provides a link where interested members of the public could 

access the Washington Area Maintenance Plan. Following EPA’s public comment period, 

responses to any comments received on the proposed mobile budgets will be addressed in an 

amendment to this TSD.

This TSD will be an enclosure to the letters from EPA to the Maryland Department of the 
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Environment (MDE), the Virginia Department of Environmental Quality (VADEQ), and the 

District of Columbia Department of the Environment (DCDOE) informing the jurisdictions of 

EPA’s findings on MVEBs of the Washington Area Maintenance Plan. EPA will publish a 

Federal Register notice announcing the adequacy findings. The effective date of the adequacy 

findings will be 15 days after the publication date of that notice. Once EPA has published the 

Federal Register notice, the letters sent to MDE, VADEQ, and DCDOE, and this TSD will also 

be posted at the EPA website.

Shown in Table 3 and Table 4 are the budgets from the Washington Area Maintenance Plan. The 

Washington Area Maintenance Plan includes a Tier 1 and Tier 2 approach for MVEBs and will 

be applied to all future transportation conformity determinations and analyses for the 1997 

annual PM2.5 NAAQS. The Tier 1 MVEBs shown in Table 3 will be the applicable motor 

vehicle emissions budgets after the adequacy findings are effective. The Tier 2 MVEBS shown 

in Table 4 adds a twenty percent (20%) transportation buffer to the mobile emissions inventory 

projections for PM2.5 and NOx in 2017 and 2025. The Tier 2 MVEBs will become effective only 

if it is determined that technical uncertainties due to model changes and to vehicle fleet turnover, 

which may affect future motor vehicle emissions inventories, lead to motor vehicle emissions 

estimates above the Tier 1 MVEBs. The determination will be made through the interagency 

consultation process and fully documented within the first conformity analysis that uses the Tier 

2 MVEBs.

Table 3. Tier 1 On-road MVEBs Contained in the Washington Area Maintenance Plan 

for the 1997 PM2.5 NAAQS

Year Motor Vehicle Emissions 

Budget for PM2.5 On-Road 

Emissions (tons per year)

Mobile Vehicle Emissions 

Budget for NOx On-Road 

Emissions (tons per year)

2017 1,787 41,709

2025 1,350 27,400

Table 4. Tier 2 On-road MVEBs Contained in the Washington Area Maintenance Plan 

for the 1997 PM2.5 NAAQS

Year Motor Vehicle Emissions 

Budget for PM2.5 On-Road 

Emissions (tons per year)

Mobile Vehicle Emissions 

Budget for NOx On-Road 

Emissions (tons per year)

2017 2,144 50,051

2025 1,586 32,880

V. Evaluation of the Adequacy of the MVEBs in the Washington Area Maintenance Plan 

for the 1997 PM2.5 NAAQS

In this TSD, we are evaluating the MVEBs associated with the Washington Area Maintenance 

Plan for conformity purposes. We are using the evaluation criteria detailed in the Transportation 

Conformity Rule, 40 CFR part 93.102(b)(2)(v), 93.102(b)(2)(v), 93.102(b)(3), and part 93, 

93.118(e)4 through 93.118(e)5. The evaluation is presented in Table 5, below.
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Table 5. Adequacy of the MVEBs Contained in the Washington Area Maintenance Plan

for the 1997 PM2.5 NAAQS

Transportation Conformity 

Rule

40 CFR Part 93, 93.118

Review Criteria Was the Criterion Satisfied? 

If Yes How was this Criteria 

Satisfied?

93.102(b)(2)(iv) Have EPA and the States

made a finding that NOx is an 

insignificant contributor to 

the direct mobile PM 

emissions?

Neither EPA nor the States

have made such a finding.

93.102(b)(2)(v) Has EPA or States made a 

finding that VOCs, Sulfur 

Oxides (SOx) or Ammonia 

(NH3) as precursors to be a 

significant contributor to the 

mobile PM2.5 emissions?

Neither EPA nor the States 

have made any findings that 

VOCs or NH3 are significant 

contributors to the PM2.5

mobile emissions, and 

therefore, they have not been 

included in the SIP. The 

States have requested that 

SO2 be found an insignificant 

contributor to the mobile PM 

emissions. This request is 

based on the States finding 

that onroad mobile source 

SO2 constitutes less than two 

percent (2%) of the area’s 

total SO2 emissions in the 

2017 and 2025 horizon years. 

Although the State requested 

insignficance, SO2 isn’t 

considered to be a significant 

contributor to mobile PM and 

therefore does not have to be 

part of a PM2.5 maintenance

strategy. 

93.102(b)(3) Has the EPA or the States

made a finding that reentrained road dust is a 

significant contributor to the 

PM mobile emissions?

Neither EPA nor the States

have made such a finding.
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Sec. 93.118(e)(4)(i) Was the submitted revised 

plan endorsed by the 

Governor (or his or her 

designee) and subject to a 

State public hearing?

Yes. The submitted 

Washington Area 

Maintenance Plan were

endorsed and submitted as a 

SIP revision by the 

Governor’s designee, the 

Secretaries of Maryland 

Department of the 

Environment and Virginia 

Department of Environmental 

Quality and the Director of 

District of Columbia 

Department of the 

Environment. A public 

hearing on the SIP proposal 

was held in all three 

jurisdictions.

Sec. 93.118(e)(4)(ii) Before the maintenance plan

was submitted to EPA, did 

consultation between federal, 

State and local agencies 

occur; was full 

implementation plan 

documentation provided to 

EPA, and was EPA’s stated 

concerns, if any, addressed?

Yes. Consultation has 

occurred among all required 

federal, state and local 

agencies.

Sec. 93.118(e)(4)(iii) Was the motor vehicle 

emissions budget(s) clearly 

identified and precisely 

quantified?

Yes, the budgets are clearly 

identified on pages 8-12 of 

the Washington Area 

Maintenance Plan prepared 

by the Metropolitan 

Washington Council of 

Governments and submitted 

by the State of Maryland, the 

Commonwealth of Virginia, 

and the District of Columbia.

Sec. 93.118(e)(4)(iv) Is the motor vehicle 

emissions budget(s), when 

considered together with all 

other emission reductions, 

consistent with applicable 

requirements for 

maintenance?

EPA believes the budgets can 

be declared adequate because 

in conjunction with the other 

emission reductions, they 

demonstrate continued 

maintenance for years 2017 

and 2025. 
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Sec. 93.118(e)(4)(v) Is the motor vehicle 

emissions budget(s) 

consistent with and clearly 

related to the emissions 

inventory and the control 

measures in the Plan?

EPA believes that the budgets 

are clearly related to the 

emissions inventory and the 

control measures in the SIP 

submittal.

Sec. 93.118(e)(4)(vi) Revisions to previously 

submitted attainment 

demonstrations: explain and 

document any changes to 

previously submitted budgets 

and control measures; 

impacts on point and area 

source emissions; any 

changes to established safety 

margins (see Sec. 93.101 for 

definition); and reasons for 

the changes (including the 

basis for any changes related 

to emission factors or 

estimates of vehicle miles 

traveled).

Yes, the Washington Area 

Maintenance Plan provides 

new MVEBs for years 2017 

and 2025. The addition of 

safety margins to the MVEBs 

is consistent with continued 

attainment. 

Sec. 93.118(e)(5) Did they provide and we 

review public comments and 

the State’s responses to those 

comments with the submitted 

control strategy SIP?

Yes

VI. Findings

Based upon our review and evaluation of the MVEBs contained in the three jurisdictions

submittals of the Maintenance Plan for the Metropolitan Washington, D.C. 1997 PM2.5 

Nonattainment Area, EPA finds the MVEBs adequate for conformity purposes and recommends 

that the MVEBs be SIP approved.