1 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION 10 

SUBJECT: 

 

Technical Support Document for Review of the Clean Data Motor Vehicle 

Emissions Budgets (MVEBs) for Fine Particulate Matter (PM2.5) and Nitrogen 

Oxide (NOx) for the Tacoma-Pierce County Fine Particulate Matter Nonattainment 

Area (Tacoma-Pierce County Area) 

FROM: Jeff Hunt <signed 6/28/2013> 

Air Planning Unit 

TO: Administrative Record of the U.S. Environmental Protection Agency’s Review of 

the Clean Data Motor Vehicle Emissions Budgets (MVEBs) for Fine Particulate 

Matter (PM2.5) and Nitrogen Oxide (NOx) for the Tacoma-Pierce County Fine 

Particulate Matter Nonattainment Area (Tacoma-Pierce County Area) 

 

I. Background 

The Environmental Protection Agency (EPA) designated the Tacoma-Pierce County Area as 

nonattainment for the 2006 24-hour PM2.5 National Ambient Air Quality Standard (NAAQS) on 

November 13, 2009 (74 FR 58688). On September 4, 2012, the EPA determined that the 

monitors in the Tacoma-Pierce County Area showed attainment of the 2006 24-hour PM2.5 

standard based on ambient air monitoring data for 2009, 2010, and 2011 (77 FR 53772). 

Additional monitoring data for 2012 shows continued attainment with a preliminary 2010-2012 

design value of 28 μg/m3. On November 29, 2012, the U.S. Environmental Protection Agency 

(EPA) Region 10 received from the Washington State Department of Ecology (Ecology) a 

request for approval and establishment of MVEBs for PM2.5 and NOx for the Tacoma-Pierce 

County Area. In accordance with the transportation conformity rule (77 FR 14982), a clean data 

area may choose to satisfy the regional conformity test by using on-road emissions from the most 

recent year of clean data as the budget. Ecology selected the year 2011 on-road emissions as the 

MVEB. 

II. Transportation Conformity Requirements 

The Federal Clean Air Act Amendments (CAA) of 1990 established "transportation 

conformity". Federal and Washington State transportation conformity regulations require 

evaluation of emissions from transportation plans, programs, and projects before they are 

implemented. These requirements apply to ozone, carbon monoxide, particulate matter, 

and nitrogen dioxide areas designated by EPA as nonattainment or maintenance. 
2 

 

Transportation conformity addresses air pollution from on-road mobile sources, which include 

cars, truck, and transit. The Federal 1990 CAA require that Federal funding and approval are 

given to transportation activities that are consistent with air quality goals. Transportation 

conformity links transportation and air quality planning processes, ensuring that the State 

Implementation Plan (SIP) achieves its goal to protect public health. Conforming to a SIP means 

that transportation activities will not cause or contribute to any new violation, increase the 

frequency or severety of any existing violation, or delay the timely attainment of any air quality 

standard in any area. 

 

Transportation plans and transportation improvement programs (TIPs), Federally funded 

projects, and regionally significant non-Federal projects are subject to transportation conformity. 

The SIP allocates emissions reductions among highway and non-highway sources and creates an 

"emissions budget" for highway sources. Conformity ensures the SIP budget as a ceiling, not to 

be exceeded. The US DOT, which includes the Federal Highways Administration (FHWA) and 

the Federal Transit Administration (FTA), and the metropolitan planning organizations (MPO) 

are responsible for transportation conformity. The MPO estimates emissions from all highway 

projects included in the transportation plan and TIPs. The FHWA and FTA approve the 

transportation plan, the TIPs, and the use of Federal funds for all Federally funded projects in the 

transportation plan and TIP. The US EPA determines the adequacy of the emissions budget. In 

Washington State, the US EPA and the Washington Department of Ecology provide a 

consultation role to the US DOT and MPO. 

In accordance with the transportation conformity regulations at 40 CFR 93.102(b)(1) and (2)(iv) 

and (v), only MVEBs for PM2.5 and NOx for the 2011 attainment year are applicable for meeting 

conformity requirements in the Tacoma-Pierce County Area. The transportation conformity rule 

requires that before a state implementation plan is submitted the area must address direct PM2.5 

emissions and must also address NOx emissions unless EPA and state have made a finding that 

transportation-related emissions of NOx are not a significant contributor to the area’s PM2.5 

problem. Therefore, the state has requested that motor vehicle emissions budgets be established 

for on-road emissions of direct PM2.5 and NOx. With regard to the remaining PM2.5 precursors 

(VOCs, SO2 and NH3) the transportation conformity rule indicates that before a SIP is submitted 

these precursors must be addressed only if either EPA or the state air agency makes a finding 

that on-road emissions of any of these precursors is a significant contributor to the area’s PM2.5

problem. Neither EPA nor the state air agency has made such a finding with regard to any of 

these precursors. Therefore, consistent with the transportation conformity rule, the state did not 

request that motor vehicle emissions budgets be established for VOCs, SO2 or NH3. 

As described in 40 CFR 93.109(c)(5) of the transportation conformity rule and the preamble of 

the Transportation Conformity Restructuring Amendments (77 FR 14982, March 14, 2012), any 

nonattainment area that EPA determines has air quality monitoring data that meet the 

requirements of 40 CFR parts 50 and 58 and that show attainment of a NAAQS (clean data), 

must satisfy one of the following requirements: (1) the budget test and/or interim emissions tests 

as required by section 93.118 and 93.119; (2) the budget test as required by section 93.118, using 

the adequate or approved motor vehicle emissions budgets in the submitted or applicable control 
3 

strategy implementation plan for the NAAQS for which the area is designated nonattainment; or 

(3) the budget test as required by section 93.118, using the motor vehicle emissions in the most 

recent year of attainment as motor vehicle emissions budgets, if the state or local air quality 

agency requests that the motor vehicle emissions in the most recent year of attainment be used as 

budgets, and EPA approves the request in the rulemaking that determines that the area has 

attained the NAAQS for which the area is designated nonattainment. The Tacoma-Pierce 

County Area may establish MVEBs under 40 CFR 93.109(c)(5)(iii) based upon EPA’s 

determination of clean data, Ecology has not submitted a maintenance plan, and EPA has 

determined (through the Clean Data rulemaking) that the Tacoma-Pierce County Area is not 

subject to the CAA reasonable further progress and attainment demonstration requirements. 

Table 1 below demonstrates how the document prepared by Washington State satisfies the 

requirements for clean data MVEBs. 

TABLE 1. EPA’S EVALUATION OF THE CLEAN DATA MOTOR VEHICLE EMISSIONS 

BUDGETS SUBMITTED BY THE WASHINGTON DEPARTMENT OF ECOLOGY FOR 

THE TACOMA-PIERCE COUNTY AREA TO EPA ON NOVEMBER 28, 2012 

CRITERIA APPLICABLE TO CLEAN DATA BUDGETS 

SECTION 

OF 

40 CFR PART 

93 

CRITERIA Y/N COMMENTS 

93.110 Are the budgets based 

upon the latest planning 

assumptions? 

Y All planning assumptions used were the 

latest available. The highway mobile 

source emission inventory was developed 

using available travel data and EPA’s 

MOVES emission model. A mix of local 

data and national default data was used for 

this analysis (based on EPA’s MOVES 

technical guidance). Local data was used 

for the primary data items that have a 

significant impact on emissions. These 

include the following: vehicle miles of 

travel (VMT) by vehicle type, average 

speed distribution, vehicle type mixes, 

source type population (for light-duty 

vehicles), vehicle age distribution, hourly 

distributions, meteorology data, 

Inspection/Maintenance program, and fuel 

supply. Most local data inputs to the 

analysis process reflect the latest planning 

assumptions based on 2011 data obtained 

from the Washington Department of 
4 

Transportation (WDOT), the Bureau of 

Motor Vehicles, and other local/national 

sources. 

93.111 Are the budgets based 

upon the latest emissions 

model? 

Y The inventory reflects the highway mobile 

source emission estimations using EPA’s 

MOVES2010b emission model, the most 

up to date model available. EPA’s MOVES 

model was officially released on March 2, 

2010 and was followed with a revised 

version, MOVES2010a, in August 2010, 

and MOVES2010b in April 2012. 

MOVES has been integrated with local 

traffic, vehicle fleet, environmental, fuel, 

and control strategy data to estimate 

emissions. The MOVES inputs that were 

prepared included vehicle type VMT, 

vehicle population, VMT fractions, 

average speed distributions, road type 

distribution and ramp fractions. These files 

were input into the MOVES county data 

importer. Additional inputs included fuel 

and vehicle ages, as well as temperatures 

and I/M programs. 

93.118 Did the state or local air 

quality agency request that 

the motor vehicle 

emissions in the most 

recent year of attainment 

be used as budgets, and did 

EPA approve the request in 

the rulemaking that 

determines that the area 

has attained the NAAQS 

for which the area is 

designated nonattainment? 

Y Ecology requested for approval and 

establishment of MVEBs for PM2.5 and 

NOx for the Tacoma-Pierce County Area 

for the attainment year 2011. EPA 

determined clean data for the TacomaPierce County Area on September 4, 2012 

for meeting the 2006 24-hour PM2.5 

NAAQS (77 FR 53772). MOVES was 

executed to provide a highway mobile 

source emission inventory. For the 2006 

24-hour PM2.5 NAAQS for the TacomaPierce County Area, the highway vehicle 

emissions of direct PM2.5 and NOx for the 

analysis year 2011 are listed below: 

2011 Emissions (pounds per winter day)

 3,002 (PM2.5) 

71,598 (NOx) 
5 

93.118(e)(4)(i) Was the request for the 

establishment of the clean 

data budgets endorsed by 

the Governor (or his or her 

designee)? 

Y Letter addressed to Dennis M. McLerran, 

Regional Administrator, EPA Region 10 

from Ted Sturdevant, Director, 

Washington State Department of Ecology. 

93.118(e)(4)(ii) Before the request that 

clean data budgets be 

established was submitted 

to EPA, 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; 

Y Letter addressed to Ted Sturdevant, 

Director, Washington State Department of 

Ecology from Puget Sound Regional 

Council. EPA Region 10 was part of the 

consultation process and raised no 

concerns. 

93.118(e)(4)(iii) Were the motor vehicle 

emissions budget(s) 

(MVEBs) clearly identified 

and precisely quantified? 

Y The submittal provides emission tables for 

the Tacoma-Pierce County Area for 

analysis year 2011. 

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

emissions budget(s), when 

considered together with 

all other emissions sources, 

consistent with applicable 

requirements for 

attainment? 

Y EPA believes that the MVEBs are 

consistent with the applicable requirements 

for attainment because the budgets are 

based on the motor vehicle emissions in the 

most recent year of attainment and EPA 

has made a determination of clean data for 

the Tacoma-Pierce County Area meeting 

the 2006 24-hour PM2.5 NAAQS, based on 

ambient air monitoring data for 2009, 

2010, and 2011. 

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

emissions budget(s) 

consistent with and clearly 

related to the emissions 

inventory and the control 

measures in the submitted 

conformity analysis? 

Y EPA believes that the motor vehicle 

emissions are clearly related to the 

emissions inventory. The most recent 

control measures approved to curtail PM2.5 

emissions in the Tacoma-Pierce County 

Area address residential wood combustion 

and have no impact on state or local motor 

vehicle related control measures. 
6 

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

submitted maintenance 

plan: 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). 

N/A This section does not apply because the 

budgets are not being established through 

an attainment demonstration or 

maintenance plan. The newly established 

MVEBs are clean data budgets and are not 

required to be submitted with an attainment 

demonstration or a maintenance plan. 

CONCLUSION 

Based upon our review and evaluation of the clean data MVEBs estimated in the Tacoma-Pierce 

County Area analysis, the EPA finds that the conformity analysis meets the requirements of the 

CAA and the applicable regulations promulgated at 40 CFR part 93. Therefore, the EPA is 

proposing to approve the establishment of the clean data MVEBs for the year 2011 for the 

Tacoma-Pierce County Area. The development methodology of the MVEBs is consistent with 

applicable guidance documents intended for the development of on-road inventories and 

MVEBs. EPA reviewed the ambient air monitoring data for 2009, 2010, 2011, and 2012 and 

determined clean data for the Tacoma-Pierce County Area, meeting the 2006 24-hour PM2.5 

NAAQS. As a result, the Tacoma-Pierce County Area may establish MVEBs under 40 CFR 

93.109(c)(5)(iii). By establishing clean data MVEBs, the Puget Sound Regional Council, the 

Metropolitan Planning Organization for the Tacoma-Pierce County Area, can compare emissions 

estimated for future transportation planning to the 2011 clean data MVEBs that were developed 

using MOVES.