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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION III

1650 Arch Street

Philadelphia, Pennsylvania 19103

 

DATE:

SUBJECT:

October 29, 2013

Technical Support Document (TSD) - Insignificance Findings for the Motor 

Vehicle Emissions for the Redesignation Requests and Maintenance Plans for the 

Charleston, West Virginia 1997 and 2006 Fine Particulate Matter (PM2.5) National 

Ambient Air Quality Standards (NAAQS) Nonattainment Area 

FROM: Gregory Becoat /s/

Environmental Scientist (3AP30)

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

Emissions for the Redesignation Requests and Maintenance Plans for the 

Charleston, West Virginia 1997 and 2006 Fine Particulate Matter PM2.5 NAAQS 

Nonattainment Area

THRU: Cristina Fernandez, Associate Director /s/

Office of Air Program Planning (3AP30)

I. Background

On December 6, 2012, the State of West Virginia (WV) formally submitted Redesignation 

Requests and Maintenance Plans for the Charleston, WV 1997 and 2006 PM2.5 Nonattainment 

Area (hereafter the Redesignation Requests and Maintenance Plans). The State Implementation 

Plan (SIP) revision included a request for findings of insignificance by Environmental Protection 

Agency (EPA) for motor vehicle emissions for nitrogen oxides (NOx) and direct particulate 

matter (PM).

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 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 
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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 motor vehicle emissions 

budgets (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 

factors or estimates of vehicle miles traveled).

In certain instances, the Transportation Conformity Rule allows areas to forgo establishment of a 

MVEB where it is demonstrated that the regional motor vehicle emissions for a particular 

pollutant or precursor are an insignificant contributor to the air quality problem in an area. The 

general criteria for insignificance determinations can be found in 40 CFR 93.109(f). 

Insignificance determinations are based on a number of factors, including the percentage of 

motor vehicle emissions in the context of the total SIP inventory; the current state of air quality 

as determined by monitoring data for the relevant NAAQS; the absence of SIP motor vehicle 

control measures; and the historical trends and future projections of the growth of motor vehicle 

emissions. EPA’s rationale for providing for insignificance determinations is described in the 

July 1, 2004, revision to the Transportation Conformity Rule at 69 FR 40004. Specifically, the 

rationale is explained on page 40061 under the subsection XXIII.B. entitled, “Areas With 

Insignificant Motor Vehicle Emissions.” Any insignificance determination under review of EPA 

is subject to the adequacy and approval process for EPA's action on the SIP.

II. Administrative Requirements for Making Insignificance Findings 

EPA has followed the process for reviewing the submitted SIP and determining if an

insignificance finding for motor vehicle emissions is warranted in accordance with the 

procedures listed in the January 2008 Conformity Regulations contained in 40 CFR 93.102(b) -

“Geographical applicability,” which applies to all nonattainment and maintenance areas for 

transportation-related criteria pollutants for which the area is designated nonattainment or has a 

maintenance plan, and 40 CFR 93.118(f) - “Adequacy review process for implementation plan 

submissions,” which describes the procedures for reviewing the adequacy of an implementation 

plan submittal.
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III. Evaluation of the Request for an Insignificance Finding for Motor Vehicle Emissions 

in the Redesignation Requests and Maintenance Plans for the Charleston, WV 1997 and 

2006 PM2.5 Nonattainment Area Submitted by the West Virginia Department of 

Environmental Protection

In this TSD, EPA is evaluating the West Virginia Department of Environmental Protection’s 

request for an insignificance finding for motor vehicle emissions associated with the 

Redesignation Requests and Maintenance Plans contained in the submittal. EPA is using the 

evaluation criteria detailed in the Transportation Conformity Rule, 40 CFR 93.102(b)(2)(iv),

(b)(2)(v), and (b)(3) and 93.118(e)(4) and (e)(5). A summary of EPA’s evaluation and the 

required review criteria of sections 93.102(b)(2)(iv), (b)(2)(v), and (b)(3) and 93.118(e)(4) and 

(e)(5) are presented in Table 1 below.

Table 1. Review of the Request for Insignificance Finding of Motor Vehicle Emissions in 

the Redesignation Requests and Maintenance Plans for Charleston, WV 1997 and 2006 

PM2.5 Nonattainment Area 

Transportation Conformity Rule

40 CFR Part 93

Review Criteria Was the Criterion Satisfied? 

If Yes, How was this Criteria 

Satisfied?

93.102(b)(2)(iv) Has the EPA and the State 

made a finding that NOx is 

an insignificant contributor 

to the direct mobile PM 

emissions or does the

implementation plan fail to 

establish a NOx budget as 

part of the PM2.5

maintenance strategy?

The State has requested that 

NOx be found an insignificant 

contributor to the mobile PM 

emissions. This request is 

based on the State finding that 

onroad mobile source NOx 

constitutes about twelve 

percent (12%) and eight 

percent (8%) of the area’s total 

NOx emissions in the

2018 and 2025 horizon years, 

respectively due to continuing 

fleet turnover even with future 

vehicle miles traveled (VMT) 

growth included in the 

emission projections. EPA has 

also made a finding that the 

transportation-related 

emissions of NOx within the 

nonattainment area are not a 

significant contributor to the 

direct mobile PM emissions.

93.102(b)(2)(v) Has the EPA or State made a 

finding that the precursors, 

Neither EPA nor WV has

made any findings that VOCs 
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Volatile Organic Compounds 

(VOCs), sulfur dioxide (SO2)

or Ammonia (NH3) are a 

significant contributor to the 

mobile PM emissions or does

the implementation plan 

submission establish a 

budget for VOCs, SO2 or 

NH3 as part of a PM2.5

maintenance strategy?

or NH3 are significant 

contributors to the PM2.5

mobile emissions, and 

therefore, they have not been 

included in the SIP. The State 

has requested that SO2 be 

found an insignificant 

contributor to the mobile PM 

emissions. This request is 

based on the State finding that 

onroad mobile source SO2 

constitutes less than two 

tenths of one percent (<0.2%) 

of the area’s total SO2 

emissions in the 2018 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 State 

made a finding that direct 

PM is a significant 

contributor to the PM mobile 

emissions or does the 

implementation plan 

establish a budget that 

includes direct PM as part of 

a PM2.5 maintenance 

strategy?

WV has requested that direct 

PM be found an insignificant 

contributor to the mobile PM 

emissions. This request is 

based on the State finding that 

onroad mobile source PM2.5 

constitutes less than two 

percent (<2%) of the area’s 

total PM2.5 emissions in the 

2018 and 2025 horizon

years due to continuing fleet 

turnover even with future 

VMT growth included in the 

emission projections. 

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 

Redesignation Requests and 

Maintenance Plans were 

endorsed and submitted as a 

SIP revision by the Governor’s

designee, the Cabinet 
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Secretary of the West Virginia

Department of Environmental 

Protection. A public hearing 

on the SIP proposal was held

on November 27, 2012. 

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) Were the MVEBs clearly 

identified and precisely 

quantified?

As there was a request for an 

insignificance finding, no 

MVEBs were identified in the 

SIP. 

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

emissions, when considered 

together with all other 

emission reductions, 

consistent with applicable 

requirements for 

maintenance strategies?

EPA believes that motor 

vehicle emissions can be 

declared insignificant 

contributors because in 

comparing the motor vehicle

emissions to the overall 

emissions inventory, the motor 

vehicle emissions comprise

only a small portion of the 

overall PM2.5 emissions for the 

nonattainment area and are 

projected to continue to 

significantly decline due to 

fleet turnover.

Sec. 93.118(e)(4)(v) Are the motor vehicle 

emissions consistent with 

and clearly related to the 

emissions inventory and the 

control measures in the Plan?

EPA believes that the motor 

vehicle emissions have clearly 

related to the emissions 

inventory and control 

measures in the SIP submittal.

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

submitted maintenance plan: 

explain and document any 

changes to previously 

submitted budgets and 

There are no revisions to the 

maintenance plans because 

this is the initial redesignation 

request, along with the 

associated maintenance plans
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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).

for the Charleston, WV Area.

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?

There were no comments on 

the SIP related to the proposed 

insignificance finding request.

IV. Conclusions

Based upon our review and evaluation of the motor vehicle emissions contained in the West 

Virginia Redesignation Requests and Maintenance Plans for the Charleston, WV 1997 and 2006 

PM2.5 NAAQS Nonattainment Area, EPA finds that the SIP submittal meets the criteria in the 

transportation conformity rules for an insignificance finding for NOx and PM2.5 contribution 

from motor vehicles. Weighing all the factors for an insignificance finding, particularly the 

minor contribution of mobile source PM2.5 and NOx, EPA has determined that the PM2.5 and 

NOx contribution from motor vehicle emissions to the PM2.5 pollution for the Charleston, WV

Nonattainment Area is insignificant. In particular, for the 2008 base year, the direct PM onroad 

mobile source constitutes 3.62% of the area’s total PM2.5 emissions and decreases significantly in 

later analysis years to 1.89% (2018) and 1.40% (2025). With respect to transportation 

conformity, the NOx contribution is twelve percent (12%) and eight percent (8%) of the area’s 

total NOx emissions in the 2018 and 2025 horizon years and requires further justification to 

request an insignificant finding. The requirements under 40 CFR 93.109(f) bases insignificance 

on emission percentages, emission trends, and the effectiveness of the pollutant in forming PM. 

For the Charleston Area, there is a significant emission decrease projected for the highway sector 

and total emissions source inventory in years 2008, 2018, and 2025. Given the relatively small 

contribution of the highway mobile emissions to the total SIP inventory, highway mobile 

emissions are not likely to contribute significantly to local PM2.5. Additionally, NOx reductions 

are significantly less effective in reducing PM concentrations than are reductions in direct PM 

and NOx. Consequently, NOx percentage emission contribution may be higher than direct PM 

and NOx without adversely affecting air quality. Based on the analysis of local historical trends 

and growth patterns in order to develop the long range transportation plan and transportation 

improvement program for transportation conformity purposes, EPA has no reason to expect 

highway motor vehicle emissions growth to lead to a violation of the 1997 and 2006 PM2.5

standard. Although vehicle miles traveled increases over time, NOx onroad emissions are 
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projected to decrease dramatically from 10,776 tons/year in 2005 to 2,134 tons/year in 2040. 

This demonstrates that highway emissions will remain insignificant in the future. Upon review

of the further justification for requesting an insignificant finding for direct PM and NOx, EPA 

has determined that direct PM and NOx contribution from motor vehicle emissions to the PM2.5 

pollution for the Charleston, WV 1997 and 2006 PM2.5 standards is insignificant.