MitchellE. Daniels. Jr. Governor
Thomas W. Easterly Commissioner INDIANA DEPARTMENT OF ENVIRONMENTAL MANAGEMENT We makeIndiana a cleaner, healthierplace to live.

100 North Senate Avenue Indianapolis, Indiana 46204 (317) 232-8603 (800) 451-6027 www.IN.gov/idem

November29, 2007

Ms. Mary Gade Regional Administrator U.S. Environmental ProtectionAgency RegionV 77 WestJackson Boulevard Chicago, IL 60604-3950 Re: Technical Addendum to the Clean Air Act Section 110(1) Demonstration for Clark and Floyd Counties, Indiana DearMs. Gade:
The Indiana Department ofEnvironmental Management (IDEM) has prepared this technical addendum to the Clean AirAct Section 110(1) Demonstration for Clarkand Floyd Counties, Indiana to incorporate Lake Michigan AirDirectors Consortium (LADCO)

- Round 5 annual PM2 .5 modeling results for the Clean AirInterstate Rule. IDEM submitted this noninterference demonstration to U.S. EPA with a request forparallel processing on October 10, 2006 and a final submission on November 15,2006 to support the discontinuation ofthe vehicle inspection and maintenance program in Clark and Floyd Counties.
LADCO Round 5 PM2.5 modelingresults, reliant on 2005 emissions and meteorological data, shows all sites in Clark and Floyd counties and in Bullitt, Hardin and Jefferson Counties in Kentuckyhave future yearmodeled design values in 2009, 2012 and 2018 well below the annual fine particles National AmbientAir Quality Standard (15.0 uglm3). This demonstration and all future yearmodeling scenarios exclude the emissionreductions associated withthe previous vehicle emissions testing program in place. Table 1.11 (to be considered an addition to the Technical SupportDocument submitted on November 15,2006) shows the LADCO

- Round 5 annual PM2.smodelingresults forCAIR.

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### R I A' I Table 1.11 I PM M d 

# r R 1 f h CI LADCO' R d5A s oun nnua 2.5 o e**lll~** csu ts or t e can If ntersta e ue 2009 Future 2012 Future 2018 Future Design Value' Design Value Design Value Design Value Monitor 10 County State 2000-2004 with CAIR with CAIR with CAIR
(ug/m3) (ug/m3) (ug/m3) (ug/m3)

180190006 Clark Indiana 16.5 13.6 13.6 13.2 180431004 Floyd Indiana 14.9 12.1 12.0 11.5 210290006 Bullitt Kentucky 14.9 12.4 12.4 12.0 210930006 Hardin Kentucky 13.5 11.2 11.2 10.7 211110043 Jefferson Kentucky 15.7 12.8 12.7 12.1 211110044 Jefferson Kentucky 15.4 12.8 12.8 12.4 211110048 Jefferson Kentucky ·15.2

. 1.2.5 12.5 12.1 211110051 Jefferson Kentucky 14.7 12.1 12.1

. 11.7
IDEM believes that this supplemental infonnation in conjunctionwith the Clean AirAct 110(1) demonstration, provides the necessary weight ofevidence to demonstrate that the discontinuation ofthe vehicle emissions testingprogram will not interfere with the area's ability to attain the annual 

### PM2.5 NAAQS by its assigneddeadline ofAprilS, 2010. IDEM also believes thatits non-interference demonstration for the year2007 remains valid, withno adverse impacts evident for the area. Therefore, IDEM hereby requests thatU.S. EPAproceed withfinal review and approval of the Clean Air Section 110(1) Demonstration for Clarkand Floyd Counties. Ifyou have any questions orneed additional information, please contact Scott Deloney, Branch Chief, at (317) 233-5684.**~nce(e1y,** 

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Attachments

cc: JayBortzer, US EPA JohnMooney, US EPA ScottDeloney, IDEMSection 110(1) Technical Support Document

Introduction for Photochemical Modeling for Ozone and PM2.5 Assessment
IDEM's Office ofAir Quality conductedphotochemical modeling to determine whetherthe discontinuation ofthe vehicle inspection and maintenance program in Clark and Floyd counties would adversely affect the area's ability to attain ormaintain compliance with applicable National Ambient Air Quality Standards. The discontinuation ofthe vehicle inspection and maintenance program does result in the loss ofNOx and VOC emission reductions, and thus could affect ozone and fine particle concentrations. This potential increase in emissions was determined using local travel demand model data and emission factors deriving from MOBILE6. The increased emissions were added to the existing emissionprofiles for Clark and Floyd counties and were modeled and compared to theprevious modeling results that included the vehicle inspection and maintenance program in Clark and Floyd counties. Any difference between the two model runs represents the impact on future year design values for ozone or PM2
.5monitors located in Clark and Floyd counties.
Emissions Estimation and Photochemical Modeling Methodologies
IDEM is amember ofthe Midwest Regional Planning Organization (MRPO), which uses photochemical modeling to determine emission control strategies for attainment State Implementation.Plans (SIPs) for Indiana, Illinois, Michigan, Wisconsin and Ohio. The Lake Michigan AirDirectors Consortium(LADCO) supports the MRPO and supplied emissions, meteorological and chemistry files as well as photochemical model source codes used inthis analysis. Indiana followed the U.S. EPA guidance in all modeling and attainment demonstration methods for this analysis.
Emissions Estimation Methodology IDEM's Office ofAir Quality adjusted the emissions in orderto determine the impact ofthe discontinuation ofthe vehicle inspection and maintenanceprogram in Clark andFloyd counties. LADCO provided the 2002 base case emissions and future year emissions for 2009 as well as the weighting factors to interpolate 2007 emissions between the 2002 and 2009 emissions. Future year2009 emissions were created to account for economic growth and emission control strategies thatwill be inplaceby 2009 for all emissions sectors. Modeling results show the downward trend for each modeled year and validates this analysis.
LADCO provided a computer softwarepatchto calculate 2007 emissions for all emissions sectors. The emissions adjustments for 2007 were an estimation ofall emission sectors between the known (2002) and calculated (2009) future emission levels. The weighting factor consists of the'fraction ofthe number ofyears from eachtime period. The weighting factors used for determining the 2007 emissions are 0.285 (2/7ths ofthe emissions from 2002) for 2002 emissions and 0.714 (5/7ths ofthe emissions from 2009) for 2009 emissions. The weighting factors were applied to the motorvehicle, low-level point, area sources (marine-air-rail, nonroad and other) and ammonia emissions. The weighting factors were not appliedto the elevatedpoint source

1emissions because no significant emission changes are expected to thatparticular source sector between 2007 and 2009. Therefore, 2009 elevatedpoint source emissions were used. Each emission sectorfile was quality assured to determine specific pollutant emissions in grammoles/day, kilograms/day and tons/day. Once emission adjustments were made, all emissions sectors were merged to create 2007 emissions.
LADCO has a computerprogram that adjusts emissions for a specific county and emission sector. Forthe purpose ofthis analysis, the discontinuation ofthe vehicle inspection and maintenanceprogram in Clark andFloyd counties only affectedmobile emissions; therefore the mobile emissions were the only emission sector analyzed. The difference between the total 2007 emissions and the total 2007 emissions with Clark and Floyd counties emissions zeroed-out, represent the mobile emissions for Clark andFloyd counties. Table 1.1 shows the modeled mobile source emissions for Clark and Floyd counties for the years 2002, 2007 and 2009. All emissions data include the vehicle inspection and maintenanceprogram in Clark and Floyd counties. The quality assured results ofthese emissions adjustments canbe found in Appendix A. Also referenced in Appendix A are the total 2007 emissions, 2007 emissions minus the Clark County emissions and the 2007 emissions minus the Floyd County emissions.

2002

- summer 2007

- summer 2009

- summer Clark Floyd Clark Floyd Clark Floyd tons/day tons/day tons/day tons/day tons/day tons/day NOx 12krTi 13.74 5.43 10.4 3.95 8.43 3'.37 36km 20.96 5.38 15.45 3.88 13.26 3.28 VOC 12km 9.46 4.00 7.93 3.03 6.11 2.65 36km 12.63 3.38 9.77 2.54 8.65 2.21 2002

- winter 2007

- winter 2009

- winter Clark Floyd Clark Floyd Clark Floyd tons/day tons/day tons/day tons/day tons/day tons/day NOx 36km 23.6 6.09 17.39 4.39 14.93 3.72 VOC 36km 13.73 3.67 10.63 2.76 9.39 2.39 Table 1.1 2002, 2007 and 2009 Mobile Source Emissions from Modeling Inventories

Based onthe MOBILE6 emissionmodeling conductedto determine the impact on NOx and VOC emissions from the discontinuation ofthe vehicle inspection and maintenanceprogram in Clark andFloyd counties, for the year2007, the increase inNOx emissions was 0.78 tons per summerday and 0.82 tons ofNOx perwinter day. VOC emissions were calculated to increase by 0.79 tons per summerday and 1.49 tons perwinter day. This change in the NOx and VOC emissions was then used to determine multipliers in orderto adjust the mobile inventory in the modeling files. The multipliers were forboth Clark and Floyd counties: NOx

- 1.047 for summerand 1.048 forwinter; VOC

- 1.125 for summer and 1.134 for winter. The emission estimates were calculated for the six wintermonths ofOctober, November, December, January, February andMarch and the six summermonths ofApril, May, June, July, August and September. The emission adjustments were then made to the 2007 mobile modeling files with

2Clark CountyNOx and VOC emissions adjusted first and the Floyd CountyNOx and VOC emissions adjusted second to account for the discontinuation ofthe vehicle inspection and maintenanceprogram in those counties. This created the new 2007 mobile emission files which were quality assured andpre-processed with the other emission source categories for use in CAMx.
Photochemical Modeling Methodology The ComprehensiveAir QualityModel with extensions (CAMx) was the photochemical model used; this model is acceptedby the U.S. EPA. The meteorology used was the summerof2002 for ozone and the entire year of2002 for PMz.5. Three separate modeling runs were conducted; one model run to determine base year (2002) concentrations, one future year (2007) model run included additional NOx and VOC emissions from the discontinuation ofthe vehicle inspection and maintenance program (without 11M), and one future year (2007) model run with the NOx and VOC emissionreductions associated with the vehicle inspection and maintenanceprogram (with IIM). The 2007 ozone and PM2.5 modeled results were post-processed and evaluatedusing the

. U.S. EPA's attainment test guidelines. Future yeardesign values were calculated from the

modeling runs with and without the vehicle inspection and maintenance programbeing inplace. The impact on the future year design values for ozone and PMz.5monitors in Clark andFloyd counties was determined.
Photochemical Modeling Results for Ozone
The resultsofthe 8-hour ozone attainment test compared the 2007 design values for Clark and Floyd countieswith the vehiCle inspectionand maintenance program inplace to the 2007 design valuesfoTClark andFloyd counties assuming the discontinuation ofthe vehicle inspection and maintenanceprogram. The difference inthe future year design values were modeled at the Charlestown, Clark County and New Albany, Floyd County ozone monitors, as well as for the additional sites within the nonattainment area. The difference is an increase inthe future year design value for ozone of+0.0001 ppm at the Charlestown ozone monitor. No difference in the future yeardesign value for the New Albany site orother sites within the nonattainment areawas determined. All design values are projectedto be below the standard of0.085 ppm. Table 1.2 lists the modeled results from the ozone attainment test and the difference in future yeardesign values as aresult ofthe discontinuation ofthe vehicle inspection and maintenanceprogram for Clark and Floyd counties. Since onlythe third significant digit is usedin computation and the modeled difference for the Charlestown site affects the fourth significant digit, there is virtually no difference in the modeled design values for any monitoring site. IDEM used the average of three design values (2000-2002, 2001-2003, and 2002-2004) for this assessment. Theperiod of time associated with the average design value encompasses the design value thatwas used in designating the areanonattainment (2001-2003) and the design value used to support IDEM's. redesignationpetition for Clark andFloyd counties (2003-2005, with 2003 representing the base year).

3, ( Table 1.2 8-hour Ozone Attainment Results for NonattainmentArea 2007 2007 NolM Difference Monitor 10 ST County 00 02 01 03 02 04 AVGDV RRF FYOV FYDV ppm ppm ppm ppm ppm ppm ppm 1801900031 IN Clark 0.090 0.092 0.088 0.090 0.93 0.083 0.083 +0.0001 1804310041 IN Floyd 0.083 0.086 0.084 0.084 0.93 0.078 0.078 0.0000 2102900061 KY Bullitt 0.085 0.081 0.076 0.080 0.94 0.076 0.076 0.0000 2111100271 KY Jefferson 0.085 0.079 0.075 0.085 0.94 0.075 0.075 0.0000 2111100511 KY Jefferson 0.084 0.084 0.080 0.084 0.94 0.077 0.077 0.0000 2111110211 KY Jefferson 0.083 0.079 0.076 0.083 0.94 0.074 0.074 0.0000 2118500041 KY Oldham 0.087 0.086 0.083 0.085 0.93 0.079 0.079 0.0000 00_02

- design value from (2000-2002), 01_03

- design value from (2001-2003), 02_04

- design value from (2002-2004), AVGDV

- average ofthe 3 design values, RRF

- relative reduction factor

- ratio offuture year and base yearmodeling, 2007 FYDV

- future year design value with Clark/Floyd I&M program, and 2007 No 1M FYDV

- future yeardesign value without ClarkiFloyd I&M program, \i Difference

- the partpermillion differencesbetween the future yeardesign values.
It shouldbe notedthat the ozone model perfonnance is within the US. EPA guidance and is considered StateImplementationPlan (SIP) quality. Infonnation 011 the attainment test, calculatingrelative-reduction factors and other additiona18.,.hour ozonedocumentation was,taken from the "Guidance on the Use ofModels and Other Analyses in Attainment Demonstrations for the 8-hour Ozone NAAQS.
Photochemical modeling was conductedby the U.S. EPA and LADCO in support oftheClean AirInterstate Rule (CAIR). The modeling results show future yeardesign values for 8-hour ozone well within the 8-hourozone NAAQS of0.085 parts permillion (ppm). Table 1.3 shows the U.S. EPAmodeling results for CAIR. All sites in Clark and Floyd counties and in Bullitt, Jefferson and Oldham Counties inKentucky are predicted to have future yeardesign values in 2010 and 2015 below 0.085 ppm and will be in attainment.
Table 1.3 8-Hour Ozone Modeling Results from U.S. EPA for the Clean AirInterstate Rule Future Future Design Value Design Value Design Value Count State MSA/CMSA 1999-2003 2010 with CAIR 2015 with CAIR m m m Clark Indiana Louisville 0.0893 0.0784 0.0735 Flo d Indiana Louisville 0.0837 0.0752 0.0703 Bullitt Kentuck Louisville 0.0837 0.0731 0.0693 Jefferson Kentuck Louisville 0.0843 0.0749 0.0711 Oldham Kentuck Louisville 0.0880 0.0756 0.0710

4Table 1.4 shows the LADCO

- Round 5 modeling results for CAIR. LADCO Round 5 modeling used emissions inventories and meteorological datataken from 2005, whichis differentthan the LADCO Round 4 modeling thatused 2002 emissions inventories and meteorology. Round 5 modeling results show all sites in Clark and Floyd counties and in Bullitt, Hardin, Jefferson and Oldham Counties in Kentucky are predicted to have future year design values in 2009, 2012 and 2018 below 0.085 ppm and will be in attainment.
Table 1.4 LADeO's Round 58-Hour Ozone Modeling Results for the Clean Air Interstate Rule 2009 Future 2012 Future 2018 Future Design Value Design Value Design Value Design Value Monitor ID County State 2003-2007 with CAIR with CAIR with CAIR (ppm) (ppm) (ppm) (ppm) 180190003 Clark Indiana 0.0790 0.0750 0.0740 0.0660 180431004 Floyd Indiana 0.0773 0.0740 0.0730 0.0660 210290006 Bullitt Kentucky 0.0740 0.0700 0.0690 0.0630 210930006 Hardin Kentucky 0.0740 0.0700 0.0690 0.0620 211110027 Jefferson Kentucky 0.0743 0.0710 0.0690 0.0630 211110051 Jefferson Kentucky 0.0780 0.0750 0.0730 0.0670 211111021 Jefferson Kentucky 0.0700 0.0670 0.0660 0.0590 211850004 Oldham Kentucky 0.0833 0.0790 0.0770 0.0690
Table 1.5 compares projected 2007 total emissions for Clark and Floyd counties with 2003 total emissionsfor Clark and floyd counties. The2007 and 2009 emission projectionsaccolintfor the discontinuation ofthe vehicle inspection and maintenanceprogram. The base yearfor Indiana's request.forClark and Floyd counties to.be redesignated toattainment under the. 8-hourozone standard is 2003. As Table 1.5 illustrates, the total emissions for 2007 and 2009 areprojected to be less than 2003 emission levels, despite the mobile source VOC andNOx emissions increasing by less than a ton eachper summerday. The 2010 and 2020 emissions referenced in the maintenanceplan remain below 2003 emissions as well, and have notbeenrevised since the vehicle emissions testing program was excluded from the calculations. As illustrated in Table 1.6, once the 2007 emissionreductionbenefit for the vehicle emissions testing program is compared to the 2003 (base year) total emissions for the entire nonattainment area, the program yields well less than a 1% emissionreductionbenefit for VOC and NOx. Historically, photochemical modeling sensitivitytests have shownthat a local reduction of15%-25% VOC is required to reduce ozone by 1 ppb.
Table 1.5 2003 and 2007 Emissions Comparison Clark and Floyd counties (tons per summer day)
2003 2007 2009 VOC 29.26 28.59 26.33 NOx 51.77 41.89 38.82
Note: 2003 emissions includethe vehicle inspection and maintenanceprogram, 2007 emissions exclude the program.

5Table 1.6 Percentage Impact of11M Emission Reduction on Base Year Emissions for Entire Nonattainment Area (tons per summer day)

VOC NOx 2003 Total 133.11 238.77 11M Benefit 0.79 0.78 % 1m act 0.6% 0.3%

Photochemical Modeling Results for Fine Particles
The attainmenttest for PM2.5 compared the 2007 design values for Clark and Floyd counties with the vehicle inspection and maintenance program inplace to the 2007 design values for Clark and Floyd counties assuming the discontinuation ofthe vehicle inspection and maintenance program. This testwas also conducted for the other sites within the nonattainment area. The difference in the future yeardesign values was modeled at the Jeffersonville, Clark County andNew Albany, Floyd CountyPM2
.5monitors as well as forthe additional sites in Bullitt andJefferson Counties in Kentucky. Table L71ists the modeledresults from the PM2.5 attainmenttestand the differencein future year design values as aresult ofthe discontinuation ofthe vehicleinspection and maintenanceprogram. The attainment testforPM2 : 5offered speciationofthe

### PM Z

.5 composition

.. This speciation includes sulfates, nitrates, .organic and elemental carbon, ammonia and soil. The impact on the annual future yeardesignyalue for PM2.5 was -0.1 uglm3 at the Jeffersonville and New AlbanyPM2

.5monitors, as well as at several ofthe Kentucky sites. These results reflect an insignificantbenefitresulting from the photochemical sensitivity associated with the affected species. The speciated modeling results ofPM2.5 mass showed a minorimpact for nitrates and ammonia from discontinuation ofthe vehicle inspection and maintenance program for Clark and Floyd counties. There are no 24-hourPM2.5 nonattainment areas in Indiana, so the 24-hourPM2.5 future yeardesign values were not calculated.

6Table 1.7
Annual PM2.5 AttainmentResults for Clark and Floyd counties 2007 2002 2007 NolM Monitor ID ST County Winter Spring Summer Fall BYDV FYDV FYDV Difference uq/m3 uq/m3 uq/m3 uq/m3 ug/m3 ug/m3 ug/m3 ug/m3 180190005 IN Clark 15.9 16.7 20.5 15.5 17.2 15.7 15.6 -0.1 180431004 IN Floyd 13.4 14.8 19.5 11.9 14.9 13.4 13.3 -0.1 210290006 KY Bullitt 13.2 15 19.9 11.4 14.9 13.5 13.4 -0.1 211110043 KY Jefferson 13.1 15.8 21.8 12.9 15.9 14.4 14.4 0.0 211110044 KY Jefferson 14.2 16.1 22.5 13.5 16.6 15.1 15.0 -0.1 211110048 KY Jefferson 13.3 15.5 22.2 13.2 16.1 14.6 14.5 -0.1
Winter'- Winterquarterly modeled average for Base Year, Spring

- Spring quarterly modeled average for Base Year, Summer-:- Summerquarterlymodeled average for Base Year, Fall- Fall quarterlymodeled average for Base Year, BYDV

- Modeled Base Year Design Value, 2007 FYDV

- future yeardesign value with Clark/Floyd I&M program, 2007 No 1M FYDV

- future year design value without Clark/Floyd I&M program, and Difference the microgrampercubic meterdifferences between the futureyeardesignvalues.
It is worth notingthat the PM2

.5model performance is outside the bounds for the bias, error, fractional bia.s and fractional errormatrices, as perU.S. EPAphotochemical modeling criteria. Improvement in the PM2
.5model performance is necessary. These modeling results may change with improvedmodel performance, however, the impacts on the annual PM2.5 future year design values are expected to be minimal. The information onthe attainment test and other additional PM2

.5documentation was taken from the "Guidance for Demonstrating Attainment ofAir Quality Goals for PM2

.5and Regional Haze".
Photochemical modeling was conductedby the U.S. EPA and LADCO in support ofthe Clean AirInterstate Rule (CAIR). The modeling results show future yeardesign values for annual PM2 .5within the annual PM2.5NAAQS of15.0 micrograms per cubic meter (ug/m3). Table 1.8 shows the U.S. EPA modeling results for CAIR. Floyd County in Indiana and BullittCountyin Kentucky are projected to attain the annual PM2.5NAAQS by 2010. All sites in Clark andFloyd counties and in Bullitt County in Kentucky are predicted to have future yeardesign values in 2015 below 15.0 ug/m3 and will be in attainment. Jefferson CountyinKentuckyis predicted to exceed the annual PM2.5NAAQS. However, it is within 3% ofthe standardin 2010 and 1% of the standard in 2015.

7Table 1.8
Annual PM25Modeling Results from U.S. EPA for the Clean Air Interstate Rule Future Future Design Value Design Value Design Value County State MSA/CMSA 1999-2003 2010 with CAIR 2015 with CAIR (ug/m3) (ug/m3) (ug/m3) Clark Indiana Louisville 16.90 15.15 14.79 Floyd Indiana Louisville 15.35 13.54 13.27 Bullitt Kentucky Louisville 15.61 13.67 13.13 Jefferson Kentucky Louisville 17.07 15.44 15.13
Table 1.9 shows the LADCO

- Round 5 modeling results for CAIR. LADCO Round 5 modeling used emissions inventories and meteorological datataken from 2005, which is different than the LADCO Round 4 modeling thatused 2002 emissions inventories and meteorology. Round 5 modeling results shows all sites in Clark andFloyd counties and in Bullitt, Hardin and Jefferson Counties in Kentucky are predicted to have future yeardesign values in 2009, 2012 and 2018 below 15.0 ug/m3 and in attainment.
Table 1.9 LADeO's Round 5 Annual PM2 5Modeling Results for the Clean Air Interstate Rule 2009 Future 2012 Future 2018 Future Design Value Design Value DesignValue Design Value

.' Monitor ID County State ' 2000-2004 with CAIR cwithCAIR with CArR

" (uq/m3) (ug/m3) (uq/m3) (uq/m3) 1801.90006 Clark Indiana 16.5 .. ' 13.6 13:6 ." 13.2 180431004 Floyd Indiana 14.9 12.1 12.0 11.5 210290006 Bullitt Kentucky 14.9 12.4 12.4 12.0 210930006 Hardin Kentucky 13.5 11.2 11.2 10.7 211110043 Jefferson Kentucky 15.7 12.8 12.7 12.1 211110044 Jefferson Kentucky 15.4 12.8 12.8 12.4 211110048 Jefferson Kentucky 15.2 12.5 12.5 12.1 211110051 Jefferson Kentucky 14.7 12.1 12.1 11.7

Table 1.10 summarizes total NOx emissions for Clark andFloyd counties for the years 2002 (base year for the 

### PM2.5 standardwith lIM inplace), 2007 (assuming the discontinuation ofthe lIM program), and 2009 (the deadline for monitoring attainment ofthe standard). As Table 1.10 illustrates, total NOx emissions for the years 2007 and 2009, with the reductions associatedwith the vehicle emissions testingprogram excluded, are less than the total NOx emissions in 2002 (thebase yearfor the standard) when the program was inplace.

8

### Table 1.10
NOx Emissions Analysis for PM2.5 

### Clark and Floyd counties (tons per day)

Conclusions
IDEM's Office ofAir Quality conducted an ozone and 

### PM 2
.sassessment to determine ifthere would be impacts from additional mobile source VOC and NOx emissions as aresult ofthe discontinuation ofthe vehicle inspection and maintenanceprogram for Clark and Floyd counties. Photochemical modeling was conducted for the summerof2002 for ozone and the entire year of 2002 for

### PM 2
.

### s. CAMx is the

## u.s. EPA accepted photochemical model used in conjunction with emissions and chemistry files obtained from the MRPO. Emission adjustments were made to the in orderto create a 2007 emissions profile. The motorvehicle emissions for Clark and Floyd counties were determined and the anticipated increase in NOx and VOC emissions were added tothe 2007 emissions inventory. e Modeling resultswere usedin the U.S. EPA attainment tests for 8-hourozone and.annual 

### PM 2.s to determine ifadditional VOC and NOx emissions associated with the discontinuation ofthe vehicle inspection and maintenance program would impactthe ozone and PM2smonitors in the nonattainment area, Based on the attainment tests, there was an increase of+0.0001 ppm for the future year ozone design value at the Charlestown ozone monitor. Since only the third significant digit is used in computation and the modeled difference for the Charlestown site affects the fourth significant digit (.0001), there is virtuallyno difference in the modeled design values for either site in Clark and Floyd counties. The projected design value for 2007(.084 ppm) is below the 8-hourozone standard and identical to the design value that serves as the base year in the redesignationpetition and maintenanceplan (2003-2005, with 2003 serving as the base year). More importantly, once the discontinuation ofthe vehicle inspection and maintenance program is accounted for, 2007 VOC and NOx emissions are projectedto be lowerthan 2003 NOx and VOC emission levels. Therefore, the discontinuation ofthe vehicle inspection and maintenanceprogram for Clark and Floyd counties will not interfere with attainment ofthe 8- hour ozone standard (or any other applicable requirement ofthe Clean AirAct).
A difference of-0.1 uglm3 ofthe annual future year design values for several monitors within the nonattainment areawas found, with the difference coming from nitrate concentrations. Though this reflects apotentialbenefit, a one-tenth ofamicrogramper cubic meter impactis negligible. More importantly, an emission analysis demonstrates that total NOx emissions for the years 2007 and 2009, with the reductions associated with the vehicle emissions testing program excluded, are less than the total NOx emissions in 2002 (thebase year for the standard) when the program was inplace. Therefore, the discontinuation ofthe vehicle inspection and maintenance program for Clark and Floyd counties will not interfere with the area's abilityto achieve reasonable progress towards attainment ofstandardbyits assigned deadline (April 5, 2010).



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