Mitchell E. Daniels. Jr.

Governor

Thomas W. Easterly

Commissioner

INDIANA DEPARTMENT OF ENVIRONMENTAL MANAGEMENT

We make Indiana a cleaner, healthier place to live.

100 North Senate Avenue

Indianapolis, Indiana 46204

(317) 232-8603

(800) 451-6027

www.IN.gov/idem

November 29, 2007

Ms. Mary Gade

Regional Administrator

U.S. Environmental Protection Agency

Region V

77 West Jackson Boulevard

Chicago, IL 60604-3950

Re: Technical Addendum to the Clean Air

Act Section 110(1) Demonstration for

Clark and Floyd Counties, Indiana

Dear Ms. Gade:

The Indiana Department ofEnvironmental Management (IDEM) has prepared this

technical addendum to the Clean Air Act Section 110(1) Demonstration for Clark and Floyd

Counties, Indiana to incorporate Lake Michigan Air Directors Consortium (LADCO) - Round 5

annual PM2.5 modeling results for the Clean Air Interstate Rule. IDEM submitted this noninterference demonstration to U.S. EPA with a request for parallel 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 modeling results, reliant on 2005 emissions and meteorological

data, shows all sites in Clark and Floyd counties and in Bullitt, Hardin and Jefferson Counties in

Kentucky have future year modeled design values in 2009, 2012 and 2018 well below the annual

fine particles National Ambient Air Quality Standard (15.0 uglm3). This demonstration and all

future year modeling scenarios exclude the emission reductions associated with the previous

vehicle emissions testing program in place. Table 1.11 (to be considered an addition to the

Technical Support Document submitted on November 15,2006) shows the LADCO - Round 5

annual PM2.s modeling results for CAIR.

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Table 1.11

LADCO's Round5AnnuaI PM2.5 Moderlll~ R 1 csu ts for the CIcan 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 conjunction with the Clean Air Act

110(1) demonstration, provides the necessary weight of evidence to demonstrate that the

discontinuation ofthe vehicle emissions testing program will not interfere with the area's ability to

attain the annual PM2.5 NAAQS by its assigned deadline ofAprilS, 2010. IDEM also believes

that its non-interference demonstration for the year 2007 remains valid, with no adverse impacts

evident for the area.

Therefore, IDEM hereby requests that U.S. EPA proceed with final review and approval of

the Clean Air Section 110(1) Demonstration for Clark and Floyd Counties. Ifyou have any

questions or need additional information, please contact Scott Deloney, Branch Chief, at

(317) 233-5684.

~nce(e1y,

\. ) / l 'i'! \'j plJJJI1i~ ""')

Daniel Murray,'1\. sistant ~mmlss1oner

Indiana Department ofEnvironmental Management

Attachments

cc: Jay Bortzer, US EPA

John Mooney, US EPA

Scott Deloney, IDEM
Section 110(1) Technical Support Document

Introduction for Photochemical Modeling for Ozone and PM2.5 Assessment

IDEM's Office ofAir Quality conducted photochemical modeling to determine whether the

discontinuation ofthe vehicle inspection and maintenance program in Clark and Floyd counties

would adversely affect the area's ability to attain or maintain 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 emission profiles for Clark and Floyd

counties and were modeled and compared to the previous 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

PM2.5 monitors located in Clark and Floyd counties.

Emissions Estimation and Photochemical Modeling Methodologies

IDEM is a member 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 Air Directors Consortium(LADCO) supports the MRPO and supplied emissions,

meteorological and chemistry files as well as photochemical model source codes used in this

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 order to determine the impact ofthe

discontinuation ofthe vehicle inspection and maintenance program in Clark and Floyd 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

year 2009 emissions were created to account for economic growth and emission control

strategies that will be in place by 2009 for all emissions sectors. Modeling results show the

downward trend for each modeled year and validates this analysis.

LADCO provided a computer software patch to calculate 2007 emissions for all emissions

sectors. The emissions adjustments for 2007 were an estimation of all emission sectors between

the known (2002) and calculated (2009) future emission levels. The weighting factor consists of

the'fraction ofthe number ofyears from each time 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 motor vehicle, low-level point, area sources (marine-air-rail, nonroad and other)

and ammonia emissions. The weighting factors were not applied to the elevated point source

1
emissions because no significant emission changes are expected to that particular source sector

between 2007 and 2009. Therefore, 2009 elevated point source emissions were used. Each

emission sector file 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 computer program that adjusts emissions for a specific county and emission

sector. For the purpose ofthis analysis, the discontinuation ofthe vehicle inspection and

maintenance program in Clark and Floyd counties only affected mobile 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 and Floyd 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 maintenance program in Clark and Floyd

counties. The quality assured results ofthese emissions adjustments can be 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 on the MOBILE6 emission modeling conducted to determine the impact on NOx and

VOC emissions from the discontinuation ofthe vehicle inspection and maintenance program in

Clark and Floyd counties, for the year 2007, the increase in NOx emissions was 0.78 tons per

summer day and 0.82 tons ofNOx per winter day. VOC emissions were calculated to increase

by 0.79 tons per summer day and 1.49 tons per winter day. This change in the NOx and VOC

emissions was then used to determine multipliers in order to adjust the mobile inventory in the

modeling files. The multipliers were for both Clark and Floyd counties: NOx - 1.047 for

summer and 1.048 for winter; VOC - 1.125 for summer and 1.134 for winter. The emission

estimates were calculated for the six winter months ofOctober, November, December, January,

February and March and the six summer months ofApril, May, June, July, August and

September. The emission adjustments were then made to the 2007 mobile modeling files with

2
Clark County NOx and VOC emissions adjusted first and the Floyd County NOx and VOC

emissions adjusted second to account for the discontinuation ofthe vehicle inspection and

maintenance program in those counties. This created the new 2007 mobile emission files which

were quality assured and pre-processed with the other emission source categories for use in

CAMx.

Photochemical Modeling Methodology

The Comprehensive Air Quality Model with extensions (CAMx) was the photochemical model

used; this model is accepted by the U.S. EPA. The meteorology used was the summer of2002

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 emission reductions associated with the vehicle inspection and maintenance program (with

IIM). The 2007 ozone and PM2.5 modeled results were post-processed and evaluated using the

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

modeling runs with and without the vehicle inspection and maintenance program being in place.

The impact on the future year design values for ozone and PMz.5 monitors in Clark and Floyd

counties was determined.

Photochemical Modeling Results for Ozone

The resultsofthe 8-hour ozone attainment test compared the 2007 design values for Clark and

Floyd counties with the vehiCle inspection and maintenance program inplace to the 2007 design

valuesfoTClark and Floyd counties assuming the discontinuation ofthe vehicle inspection and

maintenance program. The difference in the 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 in the future year

design value for ozone of+0.0001 ppm at the Charlestown ozone monitor. No difference in the

future year design value for the New Albany site or other sites within the nonattainment area was

determined. All design values are projected to be below the standard of 0.085 ppm. Table 1.2

lists the modeled results from the ozone attainment test and the difference in future year design

values as a result ofthe discontinuation ofthe vehicle inspection and maintenance program for

Clark and Floyd counties. Since only the third significant digit is used in 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. The period of

time associated with the average design value encompasses the design value that was used in

designating the area nonattainment (2001-2003) and the design value used to support IDEM's.

redesignation petition for Clark and Floyd counties (2003-2005, with 2003 representing the base

year).

3
, (

Table 1.2

8-hour Ozone Attainment Results for Nonattainment Area

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 year modeling,

2007 FYDV - future year design value with Clark/Floyd I&M program, and

2007 No 1M FYDV - future year design value without ClarkiFloyd I&M program, \i

Difference - the part per million differences between the future year design values.

It should be noted that the ozone model perfonnance is within the US. EPA guidance and is

considered State Implementation Plan (SIP) quality. Infonnation 011 the attainment test,

calculating relative-reduction factors and other additiona18.,.hour ozone documentation was, taken

from the "Guidance on the Use ofModels and Other Analyses in Attainment Demonstrations for

the 8-hour Ozone NAAQS.

Photochemical modeling was conducted by the U.S. EPA and LADCO in support ofthe Clean

Air Interstate Rule (CAIR). The modeling results show future year design values for 8-hour

ozone well within the 8-hour ozone NAAQS of 0.085 parts per million (ppm). Table 1.3 shows

the U.S. EPA modeling results for CAIR. All sites in Clark and Floyd counties and in Bullitt,

Jefferson and Oldham Counties in Kentucky are predicted to have future year design 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 Air Interstate 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

4
Table 1.4 shows the LADCO - Round 5 modeling results for CAIR. LADCO Round 5 modeling

used emissions inventories and meteorological data taken from 2005, which is different than the

LADCO Round 4 modeling that used 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 projectionsaccolint for the

discontinuation ofthe vehicle inspection and maintenance program. The base year for Indiana's

request.forClark and Floyd counties to.be redesignated to attainment under the. 8-hour ozone

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 and NOx emissions increasing

by less than a ton each per summer day. The 2010 and 2020 emissions referenced in the

maintenance plan remain below 2003 emissions as well, and have not been revised since the

vehicle emissions testing program was excluded from the calculations. As illustrated in Table

1.6, once the 2007 emission reduction benefit 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% emission reduction benefit for VOC and NOx. Historically,

photochemical modeling sensitivity tests have shown that a local reduction of 15%-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 include the vehicle inspection and maintenance program, 2007 emissions exclude

the program.

5
Table 1.6

Percentage Impact of 11M 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 attainment test for PM2.5 compared the 2007 design values for Clark and Floyd counties with

the vehicle inspection and maintenance program in place to the 2007 design values for Clark and

Floyd counties assuming the discontinuation ofthe vehicle inspection and maintenance program.

This test was also conducted for the other sites within the nonattainment area. The difference in

the future year design values was modeled at the Jeffersonville, Clark County and New Albany,

Floyd County PM2.5monitors as well as for the additional sites in Bullitt and Jefferson Counties

in Kentucky. Table L71ists the modeled results from the PM2.5 attainment test and the

difference in future year design values as a result ofthe discontinuation ofthe vehicle inspection

and maintenance program. The attainment testforPM2:

5 offered speciationofthe PMZ.

5

composition.. This speciation includes sulfates, nitrates, .organic and elemental carbon, ammonia

and soil. The impact on the annual future year designyalue for PM2.5 was -0.1 uglm3 at the

Jeffersonville and New Albany PM2.5monitors, as well as at several ofthe Kentucky sites. These

results reflect an insignificant benefit resulting from the photochemical sensitivity associated

with the affected species. The speciated modeling results ofPM2.5 mass showed a minor impact

for nitrates and ammonia from discontinuation ofthe vehicle inspection and maintenance

program for Clark and Floyd counties. There are no 24-hour PM2.5 nonattainment areas in

Indiana, so the 24-hour PM2.5 future year design values were not calculated.

6
Table 1.7

Annual PM2.5 Attainment Results 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'- Winter quarterly modeled average for Base Year,

Spring - Spring quarterly modeled average for Base Year,

Summer -:- Summer quarterly modeled average for Base Year,

Fall- Fall quarterly modeled average for Base Year,

BYDV - Modeled Base Year Design Value,

2007 FYDV - future year design value with Clark/Floyd I&M program,

2007 No 1M FYDV - future year design value without Clark/Floyd I&M program, and

Difference the microgram per cubic meter differences between the future year design values.

It is worth noting that the PM2.5model performance is outside the bounds for the bias, error,

fractional bia.s and fractional error matrices, as per U.S. EPA photochemical modeling criteria.

Improvement in the PM2.5model performance is necessary. These modeling results may change

with improved model performance, however, the impacts on the annual PM2.5 future year design

values are expected to be minimal. The information on the 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 conducted by the U.S. EPA and LADCO in support ofthe Clean

Air Interstate Rule (CAIR). The modeling results show future year design values for annual

PM2.5within the annual PM2.5NAAQS of 15.0 micrograms per cubic meter (ug/m3). Table 1.8

shows the U.S. EPA modeling results for CAIR. Floyd County in Indiana and Bullitt County in

Kentucky are projected to attain the annual PM2.5NAAQS by 2010. All sites in Clark and Floyd

counties and in Bullitt County in Kentucky are predicted to have future year design values in

2015 below 15.0 ug/m3 and will be in attainment. Jefferson County in Kentucky is predicted to

exceed the annual PM2.5NAAQS. However, it is within 3% ofthe standard in 2010 and 1% of

the standard in 2015.

7
Table 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 data taken from 2005, which is different than the

LADCO Round 4 modeling that used 2002 emissions inventories and meteorology. Round 5

modeling results shows all sites in Clark and Floyd counties and in Bullitt, Hardin and Jefferson

Counties in Kentucky are predicted to have future year design values in 2009, 2012 and 2018

below 15.0 ug/m3 and in attainment.

Table 1.9

LADeO's Round 5 Annual PM2 5 Modeling 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 and Floyd counties for the years 2002

(base year for the PM2.5 standard with lIM in place), 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 associated with

the vehicle emissions testing program excluded, are less than the total NOx emissions in 2002

(the base year for the standard) when the program was in place.

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 PM2.

s assessment to determine ifthere

would be impacts from additional mobile source VOC and NOx emissions as a result ofthe

discontinuation ofthe vehicle inspection and maintenance program for Clark and Floyd counties.

Photochemical modeling was conducted for the summer of2002 for ozone and the entire year of

2002 for PM2.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 order to create a 2007 emissions profile. The motor vehicle

emissions for Clark and Floyd counties were determined and the anticipated increase in NOx and

VOC emissions were added to the 2007 emissions inventory. e

Modeling resultswere usedin the U.S. EPA attainment tests for 8-hour ozone and .annual PM2.s

to determine if additional VOC and NOx emissions associated with the discontinuation ofthe

vehicle inspection and maintenance program would impact the 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 virtually no 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-hour ozone standard and identical to the design value that serves as the base year

in the redesignation petition and maintenance plan (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 projected to be lower than 2003

NOx and VOC emission levels. Therefore, the discontinuation ofthe vehicle inspection and

maintenance program for Clark and Floyd counties will not interfere with attainment ofthe 8-

hour ozone standard (or any other applicable requirement ofthe Clean Air Act).

A difference of-0.1 uglm3 ofthe annual future year design values for several monitors within

the nonattainment area was found, with the difference coming from nitrate concentrations.

Though this reflects a potential benefit, a one-tenth of a microgram per cubic meter impact is

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 (the base year for the standard) when the

program was in place. Therefore, the discontinuation ofthe vehicle inspection and maintenance

program for Clark and Floyd counties will not interfere with the area's ability to achieve

reasonable progress towards attainment ofstandard by its assigned deadline (April 5, 2010).

9