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### GUIDELIN

E FORDETERMININGTH EAPPLICABILITY OF NITROGENOXIDES REQUIREMENT S UNDE RSECTION182( 0

December199

3

U.S . Environmenta

lProtectionAgenc

y Offic eof Ai rQualit

yPlanningan

dStandards Ai rQualit

yManagemen

tDivision Researc hTrianglePark, NC 2771 1P. 3

GUIDELINE FORDETERMININ GTH E APPLICABILITY O F NITROGE NOXIDE S REQUIREMENT S UNDE RSECTION182 (f ) CONTENT S

CHAPTER S INTRODUCTION 1. 1 Genera l 1. 2 Nitroge nOxide s Supplemen t t o th e Genera l Preambl e fo r Implementatio n o f Titl e I o f th e Clea nAi r Ac t 1. 3 Sectio n 185 B Repor t 1. 4 Applicatio no f Sectio n 182(f ) Requirement s ADMINISTRATIVE PROCEDURE S 2. 1 Processing wit hth e Stat e Implementatio n Pla n (SIP ) Revisio n 2. 2 Petitio n NE T AI RQUALITYBENEFI T 3. 1 Demonstratio n 3. 2 Factor s 3. 3 Geographi c Scop e 3. 4 Scenario s 3. 5 Source s CONTRIBUT E T O ATTAINMENT 4. 1 Demonstratio n 4. 2 Episode s t o Conside r 4. 3 Geographi c Scop e 4. 4 Applicabilit yt o Area s Requesting Redesignatio nt o Attainmen t NE T OZON E AI RQUALITYBENEFI T 5. 1 Demonstratio n 5. 2 Factor s 5. 3 Attainment/Unclassifie d Portion s EXCES S EMISSION S REDUCTION S 6. 1 Genera l 6. 2 Demonstratio n MODELINGTECHNIQUE S 7. 1 Photochemica l Gri d Modeling 7. 2 Urba n Airshe d Mode l 7. 3 Regiona l Scal e Modeling 7. 4 Mode l Result s an d SI P Interfac e 7. 5 Othe r Analytica l Technique s EMISSION S ANALYSI S 8. 1 Genera l 8. 2 Biogeni c Volatil e Organi c Compoun d (VOC ) Emission sP. 4

8. 3 Year s t o Analyz e 8. 4 Scenario s t o Compar e 8. 5 Consistencywit hth e SI P 8. 6 Ne wSourc e Revie wP. 5

CHAPTE R1 INTRODUCTION 1. 1 Genera l Th e Clea n Ai r Ac t (CAA) , a s amende d i n1990 , include s ne w provision s i n sectio n 182(f ) t o contro l emission s o f nitroge n oxide s (NOx ) i n certai n ozon e nonattainmen t area s an d ozon e transpor t regions
. Sectio n182(f ) als o specifie s circumstance s unde r whic hth e ne wNO xrequirement s woul d b e limite d o r woul d no t apply
. Thi s documen t describe s EPA' s preliminaryview s o n ho wEP Ashoul d interpre t sectio n 182(f ) and th e circumstance s unde r whic hEPAwoul d determin e tha t th e ne wNO xrequirement s woul d b e limite d o r woul d no t apply
. Althoughthi s documen t include s variou s statement s tha t State s o r petitioner s mus t tak e certai n actions , thes e statement s ar e guidanc e mad e pursuan t t o EPA' s preliminaryinterpretations , an d thu s d o no t bin

d th e State s an

d th e publi c a s a matte r o f law
. Th e EPA' s interpretatio n o f th e sectio n 182(f ) provision s wil l provid e a basi s fo r subsequen t EPAapprova l o r disapprova l o f request s fo r exemptio n from th e ne wNO xrequirements
. Whil e thi s documen t contain s guidance. ' on th e interpretatio no f th e sectio n 182(f ) provisions , uniqu e circumstance s o r a s ye t unrecognize d issue s ar e likel yt o caus e case-by-cas e exception s t o arise
. Th e EPAintend s t o provid e th e publi c wit ha n opportunit yt o commen t o n an yexemptio nrequest s receive d byth e Agency.
.

1. 2 Nitroge n Oxide s Supplemen t t o th e Genera l Preambl e fo r Implementatio n o f Titl e I o f th e Clea nAi r Ac t Th e ne wNO xrequirements , whic har e summarize d below , ar e describe d i ndetai l i n EPA' s Nitroge nOxide s Supplemen t t o th e Genera l Preambl e fo r Implementatio n o f Titl e I o f the Clea nAi r Act
. Thi s guidanc e wa s publishe d i nth e Federa l Registe r o n Novembe r 25 , 199 2 (5 7 F R55620)
. Sectio n 182(f ) require s State s t o appl yth e same requirement s t o majo r stationarysource s o f N0 Xa s ar e applie d t o majo r stationarysource s o f volatil e organi c compound s (VOC)
. Th e ne wNO xrequirement s ar e reasonabl yavailabl e contro l technolog

y(RACT ) an

d ne wsourc e revie w(NSR)
. Thes e requirement s appl yt o majo r stationarysource s i ncertai n area s tha t ar e designate d nonattainmen t fo r th e ozon e nationa l ambien t ai r qualit ystandar d (NAAQS ) an d i n a n ozon e transpor t region
. Th e RAC T requirement s ar e i nsectio n182(b)(2)
. This , sectio n require s RAC T fo r majo r NOxstationarysource s i nozon e nonattainmen t area s classifie d moderat e an d above a s well—a s i n a n ozon e transpor t region
. State s ar e require d t o submi tP. 6

regulation s fo r RAC T b yNovembe r 15 , 199 2 an d source s ar e require d t o achiev e complianc e wit hRAC T b yMay31 , 1995
. Th e EPAha s define d RAC T a s th e lowes t emissio nlimitatio n tha t a particula r sourc e i s capabl e o f meeting b yth e applicatio no f contro l technologytha t i s reasonabl yavailabl e considerin g technologica l an

d economi c feasibilit y(4 4 F R53762 ; Septembe r 17 , 1979)
. Th e NS Rrequirement s ar e i n sectio n182(a)(2)(C)
. Thi s sectio n require s State s t o adop t revise d NS Rregulation s i n ozon e nonattainmen t area s classifie d margina l an d abov e a s wel l a s withi n a n ozon e transpor t region
. State s ar e require d t o submi t regulation s fo r NS Rb yNovembe r 15 , 1992
. NS Rprovision s requir e majo r ne wo r modifie d stationarysource s t o compl ywit hcontro l technologytha t represent s th e lowes t achievabl e emissio nrat e and-require s th e source s t o obtai n emissio n offsets
. Th e RAC T an

d NS Rrequirement s fo r majo r source s i n attainment/unclassifie d portion s o f th e northeas t ozon e transpor t regio n originat e i n sectio n184(b)(2)
. 1. 3 Sectio n 185 B Repor t Unde r sectio n 185B , th e Administrator , i nconjunctio nwit h th e Nationa l Academ yo f Science s (NAS) , conducte d a stud yo n th e rol e o f ozon e precursor s i ntropospheri c ozon e formation
. Th e sectio n 185 B stud

ymus t examine d th e rol e o f N0 Xand VO C emissions , th e exten t t o whic hN0 Xreduction s maycontribut e o r b e counterproductiv e t o achieving attainmen t i ndifferen t nonattainmen t areas , th e sensitivit yo f ozon e t o th e contro l o f N0 X , th e availabilit yan d exten t o f control s fo r NO x , th e rol e o f biogeni c VO C emissions , an d th e basi c informatio nrequire d fo r ai r qualit ymodels
. Th e EPAannounce d i nth e February26 , 199 3 Federa l Registe r a 30-da ypubli c commen t perio d o n th e draf t sectio n 185 B report
. Th e fina l repor t wa s submitte d t o Congres s o n Jul y30 , 1993
. Th e Nationa l Researc hCounci l announce d th e completio n o f th e Decembe r 199 1 NA S report , Rethinking th e Ozon e Problemi n Urba n an d Regiona l Ai r Pollution
. Th e fina l sectio n 185 B repor t incorporate s thi s NA S repor t along wit ha recen t EPA repor t addressing th e availabilit yan d exten t o f NO xcontrols
. I n addition , th e sectio n 185 B repor t als o provide s EPA perspective s o n ke yozon e contro l strateg yissue s addresse d by th e Nationa l Researc hCouncil , emphasizing th e NO xissue s a s directe d b

ysectio n 185B
. I n makin g a determinatio n unde r sectio n 182(f ) that , th e NO x requirement s d o no t apply , o r mayb e limited , th e EPAmus t conside r th e sectio n185 B study
. Thi s sectio n182(f ) documen t include s consideratio n o f EPA' s sectio n 185 B repor t t o Congress , including th e Decembe r 199 1 NA S report
.P. 7

1. 4 Applicatio n o f Sectio n 182(f ) Requirement s Sectio n 182(f)(1 ) provide s tha t th e ne wNO xrequirement s shal l no t appl yi f th e Administrato r determine s tha t an yon e o f th e followin g test s i s met : (1 ) i n an yarea , th e ne t ai r qualit ybenefit s ar e greate r i n th e ab s concerned ; i n th e absenc e o f N0 Xreduction s fro mth e source s
(2 ) i nnonattainmen t area s no t withi na nozon e transpor t region , additiona l N0 Xreduction s woul d no t contribut e t o ozon e attainmen t i n th e area ; o r (3 ) i n nonattainmen t area s withi n a nozon e transpor t region , additiona l N0 Xreduction s woul d no t produc e ne t ozon e ai r qualit ybenefit s i n th e transpor t region
. Further , sectio n182(f)(2 ) state s tha t th e applicatio no f th e ne wNO xrequirement s ma yb e limite d t o th e exten t necessar y t o avoi d exces s reduction s o f NO xa s determine d b yapplyin g test s simila r t o test s (l)-(3 ) above
. A s describe d i nthi s document , th e "ne t ai r qualit y benefits " tes t an d th e "exces s emissions " provisio nma yb e applie d i n a n ozon e transpor t regio n o r outsid e th e transpor t region ; th e "contribut e t o attainment " tes t ma yonl yb e applie d outsid e o f a nozon e transpor t region ; an d th e "ne t ozon e benefits " tes t ma yonl yb e applie d withi na nozon e transpor t region
. Wher e an yon e o f th e test s i s me t (eve ni f anothe r tes t i s failed) , th e sectio n182(f ) NO xrequirement s woul d no t appl y or , unde r th e exces s reduction s provision , a portio no f thes e requirement s woul d no t apply
.



# JP. 8

CHAPTE R2 ADMINISTRATIVE PROCEDURE S
. 2. 1 Processing wit hth e Stat e Implementatio nPla n(SIP ) Revisio n AStat e may , a t an ytime , demonstrat e t o th e Administrato r tha t th e ne wNO xrequirement s shoul d no t apply
. Fo r example , a Stat e ma ysubmi t a demonstratio n unde r sectio n 182(f ) alon g with , o r a s a revisio n to , th e SI P a t th e time th e NO xRAC T rule s ar e due ; o r a Stat e maychoos e t o submi t th e sectio n 182(f ) demonstratio n a t a late r dat e along wit ho r a s par t o f a separat e SI P revision
. Th e State' s demonstratio n i s no t require d t o b e a SI P revisio n itself
.
* Th e EPAwil l approv e o r disapprov e th e State' s demonstratio n whe n th e Administrato r approve s a pla n o r pla nrevision
. Th e EP A wil l conside r th e sectio n 185 B repor t and wil l bas e it s decisio n o n th e demonstratio n and supporting informatio nprovide d b yth e State
. Suc hdemonstratio n an d informatio nshoul d b e i n sufficien t detai l for/EPAt o determin e tha t th e exemptio n reques t i s consisten t wit hth e guidance-containe d i nthi s sectio n182(f ) document
. Th e EPAencourage s th e State s t o consul t wit hth e appropriat e EPARegiona l Offic e during th e developmen t o f th e documentation
. Thi s i s necessaryt o ensur e tha t th e documentatio n provide d b yth e Stat e i s likel yt o b e approve d and tha t an yrequire d rule s can b e adopte d i na timel ymanner . NO x RAC T and/o r NS Rrule s tha t hav e bee n submitte d o r wer e previousl y approve d b

yEPAwoul d continu e t o b e processe d fo r approva l o r continu e t o b e enforce d whil e EPAconsidere d th e sectio n182(f ) demonstration
. 2. 2 Petitio n Sectio n 182(f)(3 ) provide s tha t a perso n(including a State ) ma ypetitio n th e Administrato r fo r a N0 Xexemptio na t an ytim e afte r th e fina l seqt^io n 185 B repor t i s submitte d t o Congress
. Th e petitio nmayb e mad e wit hrespec t t o an ynonattainmen t are a o r an yozon e transpor t region
. Th e EP Amus t gran t o r den ya petitio n withi n6 month s afte r it s filing
. Sinc e a n individua l petitio ni s likel yt o affec t th e SI P plannin g proces s whic hi s primaril ya Stat e responsibility , EP A believe s i t i s reasonabl e t o requir e th e petitione r t o provid e a copyo f th e petitio n an d demonstratio n t o th e Stat e o r State s whic hhav e jurisdictio n ove r th e sourc e o r source s covere d b yth e petitio n a t th e sam e tim e i t i s submitte d t o th e Administrato r (wher e a petitio n unde r sectio n182(f)(3 ) i s being submitte d bya perso n othe r tha n th e Stat e itself )
. Wher e additiona l State s ma y b e affecte d b

yth e petition , th e Stat e receiving th e petitio n shoul d coordinat e wit hth e othe r State s a s necessary . -In-som e case s ther e mayb e multipl e petition s fo r a give n area . I nothe rP. 9

case s a singl e petitio nmayhav e multi-Stat e implications
. Shortl yafte r EPAreceive s a petition , th e Agenc ywil l announc e it s receip t and availabilit yfo r publi c revie wi n th e Federa l Register
. Th e EPAwil l provid e th e State(s ) a 3-mont hperio d t o mak e a recommendatio n t o EPAregarding th e petition
. Thi s 3

- mont hperio d wil l run concurrentl ywit hth e 6-mont hrevie wperio d require d unde r sectio n 182(f)(3)
. Th e petitione r shoul d submi t th e petitio n and demonstratio nt o th e Administrato r throug hth e appropriat e EPARegiona l Office
. Th e EPAencourage s an ypetitione r t o consul t wit hth e Stat e ai r qualit yagenc yan d th e appropriat e EP ARegiona l Offic e durin g th e developmen t o f a sectio n182(f ) demonstration
. Thi s i s necessaryt o ensur e tha t th e documentatio nprovide d (1 ) meet s EP A guidance , (2 ) doe s no t conflic t wit hsimila r analyse s b yth e State , and (3 ) i s likel yt o b e accepte d b yth e Stat e an

d EPA
. Th e EPA' s decisio nt o gran t o r den ya petitio n wil l includ e consideratio n o f th e sectio n185 B repor t an d wil l b e base d o n th e demonstratio nprovide d b yth e petitioner , th e State' s recommendation , an

d th e provision s o f sectio n182(f)
. A s note d above , thi s documen t set s fort hEPA' s preliminaryinterpretation s o f th e sectio n 182(f ) provisions ; Th e EPAwil l provid e notic e o f it s fina l actio no n a petitio n and th e rational e fo r tha t actio n i na lette r t o th e petitione r withi n th e 6 mont hperiod
. I naddition , EP Awil l publis ha notic e describing th e petitio n an d EPA' s determinatio n

, i n th e Federa l Register
. I f EPAdenie s a petition , th e petitione r ma ysupplemen t o r revis e the origina l petitio na t a late r date
. Anyrevise d petitio n woul d begi n a ne w6 mont h period
. I f EPAgrant s a petition , th e sectio n182(f ) NO x requirement s o r portion s o f thos e requirements , woul d n o longe r appl yt o thos e source s o r areas > a s describe d i nEPA' s approva l action
. However , State s remai n fre e t o adop t N0 Xrestriction s fo r othe r reasons . • Fo r example , a Stat e maydetermin e tha t NO x reduction s ar e neede d fo r purpose s o f ozon e maintenanc e planning , ozon e attainmen t i n separat e downwin d nonattainmen t areas , visibilit yprotection , PM-1 0 contro l strategy , aci d depositio n progra mo r othe r environmenta l protection
. Th e EPAcoul d approv e certai n NO xrestriction s i n a SI P revisio ndespit e grantin g a petitio n unde r sectio n 182(f) , s o lon g a s the NO xrestriction s woul d no t interfer e wit hmeeting an yapplicabl e requiremen t concerning attainmen t an d reasonabl e furthe r progres s o r any othe r applicabl e requiremen t o f th e CA A[se e sectio n 110(1)]
. Sectio n 182(f)(3 ) state s tha t a perso nmaypetitio nth e Administrato r fo r a determinatio nunde r sectio n182(f ) a t any time afte r th e fina l repor t unde r sectio n 185 B i s submitte d t o Congress
. Th e fina l sectio n 185 B repor t wa s sen t t o Congres s b y th e Administrato r o n Jul y30 , 1993
. Sectio n182(f)(3 ) als oP.1 0

require s th e Administrato r t o gran t o r den ysuc ha petitio n withi n . 6 month s afte r it s filing wit hEPA
.P.1 1

CHAPTE R3 NE T AI RQUALITYBENEFI T 3. 1 Demonstratio n Thi s demonstratio n applie s t o specifi c source s i na n ozon e nonattainmen t are a o r i na n ozon e transpor t region
. I t mus t sho w tha t N0 Xreduction s from th e source s seeking th e exemptio nwoul d b e counter-productiv e overall , considering th e ne t ai r qualit y benefits
. Congres s specifie d i nthi s "test " fo r specifi c source s a highe r hurdl e tha ni nth e othe r test s fo r areawid e exemptions : th e demonstratio n mus t showa beneficia l impac t fromth e avoidanc e o f th e NO xcontrols
.

• Th e procedur e fo r thi s tes t i s t o firs t projec t areawid e baselin e condition s tha t mayb e expecte d a t th e attainmen t deadlin e (section8.3)
. Then , analyse s ar e conducte d fo r 2 scenario s (section 3.4) : wit han d withou t NO xreduction s a t th e source s concerned
. As'describe d i nsectio n8.2 , multi-yea r analyse s mayals o b e conducted
. 3. 2 Factor s Unlik e th e test s describe d i n chapter s 4 an d 5 , th e CA

Adoe s no t limi t thi s tes t t o consideratio no f ozon e impacts
. Instead , thi s tes t i s base d o n a broade r se t o f ai r qualit yimpact s \Considered i nth e CAA
. Ther e ar e man yai r qualit yimpact s explicitl yaddresse d i n th e CAA , bot hhealt han d welfar e related , tha t mayb e directl yo r indirectl yrelate d t o NO xemissions
. Thes e impact s includ e ozone , nitroge n dioxide , an d particulat e matte r formation , visibilit yimpairment , aci d deposition , ai r toxic s formation , an d nitroge ndepositio n i n nutrient-sensitiv e areas . Du e t o th e numbe r an d variet yo f impacts , i t i s generall y impractica l o r imppssibl e t o compar e effect s quantitativel yfro m on e o f thes e factor s t o thos e fro manothe r facto r o r amon g severa l factors
. Fo r example , ther e i s n o readil yavailabl e scal e t o us e t o compar e nitroge n dioxid e impact s wit haci d depositio n impact s and/o r visibilit yimpacts
. Thus , i norde r t o describ e a metho d fo r determining th e "ne t ai r qualit ybenefit, " a distinctio n mus t b e mad e regarding whic ho f th e manyfactor s can an d shoul d b e analyzed
. Th e EPAha s conclude d tha t th e factor s considere d fo r th e purpose s o f sectio n182(f ) mus t b e consisten t wit hth e requirement s o f th e CAA
. Thus , althoug h"ai r qualit yimpacts " coul d potentiall yb e define d i n a verybroad manner , EPAha s conclude d tha t th e ai r qualit yimpact s considere d unde r sectio n 182(f ) mus t relate d directl yt o goals , standards , o r mandate s tha t ar e explicitl yaddresse d i nth e CAA
. Therefore , th e tes tP.1 2

fo r ne t ai r qualit ybenefit s mus t assur e tha t a decisio nt o gran t a n exemptio n woul d no t interfer e wit hth e achievemen t o f th e specifi c program s o r goal s mandate d i n th e CAA
. Th e primar ytes t shoul d b e th e effec t th e exemptio n woul d hav e o n attainmen t o f th e primaryNAAQ S fo r th e criteri a pollutants
. Th e primaryNAAQ S ar e se t byth e Administrato r t o assur e protectio n o f th e publi c healt hwit ha n "adequat e margi n o f safety; " EPAhas , thus , conclude d tha t thi s tes t shoul d focu s specificall yo nth e effec t o f an exemptio n o n th e number s o f exceedance s o f th e primaryNAAQS , Apetitione r shoul d mode l th e "NO xcontrol " vs . "no NO xcontrol " scenario s t o asses s th e impac t th e NO xcontrol s woul d hav e o nth e number s o f exceedance s o f th e primaryNAAQS , a s describe d elsewher e i nthi s document
.
* Secondarytests , a s needed , ca nextend t o th e (qualitativ e o r quantitative ) consideratio n o f othe r ai r qualit yimpact s tha t ar e explicitl yrecognize d i nth e CAA
. Thes e coul d include , fo r example , th e welfar e effect s whic hEP Aha s considere d an d deeme d necessaryt o protec t agains t i n setting secondaryNAAQ S fo r th e criteri a pollutants
. A petitione r coul d als o conside r an yothe r ai r qualit yeffect s tha t ar e explicitl yaddresse d i nth e CA A throughgoals , standard s o r mandates , fo r example , visibilit yo r ai r toxic s emissions
. Th e CA Arequire s th e NAAQ S t o b e attaine d a s expeditiousl y a s practicabl e an

d th e CA

Ainclude s deadline s fo r rul e adoption , submitta l o f contro l strategies , an d attainmen t o f th e primar y nationa l ambien t ai r qualit ystandard s (NAAQS)
. Thus , th e impact s o n attainmen t o f th e primaryNAAQ S mus t b e a primar y concer n t o thi s ne t ai r qualit ybenefi t test
. I n contrast , impact s o n nutrient-sensitiv e area s i s a n importan t environmenta l issu e tha t i s addresse d i nth e CAA , bu t doe s no t hav e th e sam e detaile d se t o f requirement s an d deadline s state d i nth e CA Aa s d o th e NAAQS ; thus , i t shoul d generall yb e a secondaryconcer nt o thi s ne t ai r qualit ybenefi t test
. Further , EPAi s no t awar e o f an yconflict s betwee n th e sectio n 182(f ) exemptio nand th e requirement s o f sectio n 407 , concerning aci d deposition , tha t migh t b e considere d i nthi s analysis ; i.e. , granting a sectio n 182(f ) exemptio n woul d no t relieve , conflic t with , o r otherwis e affec t a source' s obligatio no r abilityt o achiev e NO xreduction s consisten t wit hth e sectio n40 7 requirements
. I ncase s wher e NO x reduction s froma utilit ysubjec t t o sectio n40 7 woul d b e counterproductiv e t o th e ne t ai r qualit ybenefit , EPAencourage s th e Stat e and utilit yt o us e th e emissio naveraging provision s o f sectio n 40 7 t o achiev e th e require d NOxreduction s a t a locatio n wher e the yar e no t counterproductiv e t o th e ne t ai r qualit y benefit
. I f anystatutoryconflict s ar e documented , the ycoul d b e considere d o n a case-by-cas e basis
. I n al l cases , th e metho d fo r consideratio no f the

- ne t benefit s mus t b e relate d primaril yt o "ai r quality " sinc e sectio nP.1 3

182(f ) specificall yrequire s a determinatio n o f th e "ai r quality " benefits
. Thus , simple r tests , suc ha s a "ne t emissions " test , shoul d no t b e relie d upo n sinc e change s i n emission s ar e no t necessaril ydirectl yrelate d t o change s i n ai r quality
. I n general , ai r qualit yimpact s ca nb e bes t determine d byus e o f ai r qualit ydispersio nmodels
. However , a t th e presen t time , ther e ar e n o EPA-recommende d ai r qualit ydispersio nmodel s fo r simulatio no f nitrat e (particulate ) formatio no r compariso namon g ozone , nitroge n dioxide , and/o r PM-1 0 NAAQ S impact s i na singl e nonattainmen t area . I n orde r t o us e ai r qualit ydispersio n modelin g wheneve r possibl e an

d t o avoi d conflict s wit hothe r requirement s o f th e CAA , th e method s describe d belo wshoul d b e use d t o determin e th e ne t ai r qualit ybenefi t ove r a nappropriat e geographi c are a (se e sectio n 3.3 ) whic hinclude s th e ozon e nonattainmen t area s encompassing o r nearb yth e source s concerned
. Thes e method s includ e a primaryconsideratio n o f th e primaryNAAQ S ai r qualit y benefit s an

d secondaryconsideratio no f othe r ai r qualit y benefits
. Ozon e Nonattainmen t Area s ; Fo r area s tha t ar e nonattainmen t onl yfo r ozone , th e effect s o f NO xreduction s o n ozon e concentration s shoul d b e quantifie d wit hcurrentl yavailabl e ai r qualit ymodelin g technique s (se e chapte r 7)
. Th e ne t ai r qualit ybenefi t shoul d b e base d o na compariso n o f th e geographi c are a expose d t o concentration s abov e th e ozon e NAAQ S wit hand withou t NO xreduction s fromth e source s concerned
. Wher e Urba n Airshe d Mode l (UAM ) result s ar e available , populatio nexposur e t o concentration s abov e o r nea r th e NAAQ S ma y b e use d instead o f th e geographi c are a exposur e factor
. Th e Regiona l Oxidan t Mode l (ROM ) result s fo r NO xreductio n scenario s ove r majo r emissions/populatio n center s shoul d no t b e use d quantitativel yfo r -population exposur e analyses
. Thi s i s becaus e RO Mresult s hav e thei r larges t associate d uncertaintie s i n area s wher e ther e i s a n inhomogeneou s mi xo f emission s frommajo r sources . Sinc e suc harea s als o tend t o hav e greates t populations , us e o f th e ROM , b yitself , t o estimat e populatio n exposur e mayhav e considerabl e associate d uncertainty
. I t i s importan t t o not e tha t EPAbelieve s tha t photochemica l gri d model s suc ha s UA Mand RO Mar e no t sufficien t t o asses s incrementa l change s t o areawid e ozon e concentration s from emission s reduction s a t a singl e o r group o f smal l sources . Emissio n change s shoul d amoun t t o some significan t fractio n o f bas e emission s befor e modelin g result s wit hROMo r UA Mca nb e interprete d wit hsufficien t confidenc e tha t th e result s ar e no t los t i n th e nois e o f th e mode l an d th e inpu t data
. -• - —P.1 4

1 0 Th e EPAha s reservation s wit hrespec t t o modelin g NO x reduction s a t a singl e sourc e o r grou p o f source s unles s th e modeling include s a t leas t 10 % o f th e domain-wid e emissions
. Thus , thi s exemptio n analysi s i s appropriat e fo r group s o f larg e emitter s o r fo r consideratio no f entir e sourc e categories , rathe r tha n emissio n reduction s a t a singl e o r grou p o f smal l sources . However , EPAwil l conside r o na case-by-cas e basi s a nanalysi s tha t consider s les s tha n a 10 % chang e i nth e domain-wid e emissions
. I n suc hcases , th e analysi s o f a smal l portio no f th e emission s woul d sho wonl ya smal l differenc e i n ozon e concentration , i f any , betwee n th e wit hNOxan d withou t NO x scenarios , and , therefore , consideratio no f secondaryfactor s (describe d below ) i s particularl yimportan t i n orde r t o sho wa ne t ai r qualit ybenefit
. I n some cases , th e amoun t o f emissio n reduction s assume d i n th e modelin g analysi s coul d b e verylarge ; thus , ther e ma yb e case s wher e th e analysi s doe s no t resul t i n an yvalue s abov e th e NAAQ S fo r an

ypollutan t and , thus , ther e woul d no t b e a compariso n o f are a o r populatio nexposed
. Thi s coul d occu r eve n thoughth e differenc e i n ozon e concentratio nbetwee nth e tw o scenario s i s large
. I nsuc hcases , th e petitione r shoul d loo k t o th e factor s considere d i n th e secondarytest , suc ha s welfar e effect s o r othe r ai r qualit yeffect s addresse d b yth e CAA
. Area s Nonattainmen t fo r Bot hOzon e an d Nitroge nDioxid e Fo r area s tha t ar e nonattainmen t fo r bot hozon e and nitroge n dioxide , NO xreduction s clearl yar e neede d t o provid e fo r attainmen t o f th e nitroge n dioxid e standard , whil e eithe r NO xo r VO C reduction s (or both ) migh t bes t provid e fo r attainmen t o f th e ozon e standard
. I n suc hcase s EPAwoul d no t mak e a findin g o f a ne t ai r qualit ybenefi t sinc e th e CA Arequire s th e NAAQ S fo r nitroge n dioxid e t o b e me t a s expeditiousl ya s practicable
. Area s Nonattainmen t fo r Bot hOzon e an d PM-1 0 Fo r area s tha t ar e nonattainmen t fo r bot hozon e and PM-10 , a determinatio n i s firs t neede d i f th e secondarynitrate s forme d fromNO xemission s contribut e significantl yt o th e PM-1 0 NAAQ S violation(s ) i n th e specifi c nonattainmen t area . Thi s significanc e determinatio n i s neede d since , especiall yi nth e eastern Unite d States , EPAexpect s tha t th e nitrat e portio no f measure d PM-1 0 wil l b e found , t o b e insignifican t i n manycases . Wher e sufficien t an d reliabl e dat a exis t t o determin e th e nitrat e contributio nt o ambien t PM-1 0 concentrations , thi s determinatio n mayb e limite d t o thos e NO xemission s source s subjec t t o th e sectio n 182(f ) requirements
. Wher e th e contributio ni s insignifican t (se e below ) , the nth e ne t ai r qualit ydeterminatio n shoul d b e base d primaril y.o n th e ozon e impacts
. Wher e th e contributio ni s significant , EP Awoul d no t mak e a findin g o f a ne t ai r qualit ybenefi t sinc e th e CA Arequire s th e NAAQ S fo r PM

-P.1 5

1 1 1 0 t o b e me t a s expeditiousl ya s practicable
. Fo r thi s purpose , EPAintend s t o us e it s definitio n o f a significan t contributio n t o a PM-1 0 nonattainmen t are a whic hi s 1. 0 microgram pe r cubi c mete r (nitrat e and associate d materials ) fo r th e annua l standar d an d 5 microgram s pe r cubi c mete r fo r th e 24-hou r standar d (4 0 CF R 51.165)
. Area s Nonattainmen t fo r Ozon e an d Carbo n Monoxide
. Lea d o r Sulfu r Dioxid e Fo r carbo n monoxide , lead , and sulfu r dioxide , EP Ai s no t awar e o f an

ysignifican t impact s fromNO xreductions
. Therefore , th e ne t ai r qualit ybenefit s determinatio nshoul d b e primaril y base d o n th e ozon e modeling analysi s describe d abov e fo r area s nonattainmen t fo r onl yozone . A s note d above , equa l consideratio n o f al l NO ximpact s i s generall yimpractica l i n thi s ne t ai r qualit ybenefi t tes t becaus e o f th e lac k o f scale s t o compar e th e impact s amon g th e variou s factors
. Nevertheless , additiona l factor s explicitl y addresse d i n th e CA Asuc ha s thos e liste d belo wmus t b e considere d a t leas t o n a qualitativ e basi s i nadditio nt o any informatio ndevelope d fromth e NAAQ S analyses
. Consideratio n o f th e factor s belo wi s especiall yimportan t i ncase s wher e th e analyse s o nth e NAAQ S pollutant s canno t clearl ydetermin e th e ne t ai r qualit ybenefit
. I n an ycase , EPAbelieve s th e amende d CA A place s a substantia l burde no nth e applican t t o provid e a clea r \Showin g tha t NO xreduction s woul d b e counterproductiv e overall , considering th e ne t ai r qualit ybenefits
. Additiona l factor s t o determin e ne t ai r qualit ybenefi t ma yinclud e bu t ar e no t limite d to : 1
. Effect s associate d wit hlong-term exposure s t o plants, animals , an

d materials
. 2
. Visibilit yimpairment , long-ter m an d episodi c aci d deposition , ai r toxics , an d depositio no f nitroge ni n nutrient-sensitiv e watersheds
. 3. 3 Geographi c Scop e I n contras t t o th e othe r sectio n 182(f ) tests , th e ne t ai r qualit ybenefi t tes t i s no t specificall ylimite d t o a nozon e nonattainmen t are a o r ozon e transpor t regio nan d ma yb e directe d a t a specifi c se t o f sources . Thus , a verybroa d geographi c are a shoul d b e considered
. Th e are a may , i n som e cases , extend beyon d a nozon e nonattainmen t are a o r ozon e transpor t region
. I n addition , th e are a mus t no t b e s o smal l tha t downwind impact s fromNO xemission s ar e no t full yconsidered
. Sufficien t are a i s neede d t o allo wfo r completio n an d consideratio no f th e variou s chemica l transformation s o f NO xan d interactio n wit hothe r pollutants
. A t a minimum , th e geographi c are a shoul d includ e th eP.1 6

1 2
ozon e nonattainmen t area(s ) encompassing o r nearb yth e source s concerned
. Fo r example , petitioning source s locate d i n attainmen t portion s o f th e ozon e transpor t regio n shoul d analyz e thei r impac t o n nearb ynonattainmen t area s an d shoul d conside r othe r factors , suc ha s visibilit yimpact s throughou t th e surroundin g are a 3. 4 Scenario s Sectio n 182(f ) states , fo r thi s test , tha t EP Amus t determin e tha t th e ne t ai r qualit ybenefit s ar e greate r i n "th e absenc e o f reduction s o f oxide s o f nitroge nfromth e source s concerned. " Th e procedur e fo r thi s tes t i s t o firs t projec t areawid e baselin e emission s tha t mayb e expecte d a t th e attainmen t deadlin e (se e section s 3. 3 an d 8.3)
. (A

s describe d i n sectio n 8.3 , multi-yea r analyse s mayals o b e conducted. ) Second , th e projecte d baselin e emission s ar e hel d constant , excep t fo r th e subjec t individua l sources . Then , th e ai r qualit yanalyse s ar e conducte d fo r thes e tw o scenarios : 1
. th e projecte d baselin e emission s o f VO C and NO x (withou t NO xreduction s fromth e source s concerned ) and 2
. th e projecte d baselin e emission s o f VO C and NO x emission s including NO xreduction s a t al l emissio n source s subjec t t o th e NOxNS Ran d RAC T provision s o f sectio n 182(f)
. Wit hrespec t t o ne wmajo r sources , th e tw o scenario s shoul d tak e int o accoun t applicatio n o f th e sectio n182(f ) NS R requirement s a s describe d i nsectio n8.5
. 3. 5 Source s Fo r thi s ne t ai r qualit ybenefi t test , th e CA Arefer s t o "reduction s o f oxide s o f nitroge nfro m th e source s concerned. " Fo r purpose s o f thi s analysis , "the source s concerned " ar e define d a s th e source s tha t woul d b e exempte d fromth e sectio n 182(f ) NO xrequirement s b yth e petitio no r Stat e request
. Th e source s concerne d mayb e identifie d i n an yo f th e followin g ways : (1 ) specifi c individua l sources , (2 ) on e o r mor e sourc e categories , o r (3 ) a geographi c are a containing a group o f sources . A s describe d i n sectio n3.4 , th e source s concerne d mus t b e analyze d togethe r wit hothe r NOxan d VO C source s i n th e area ; thes e othe r NO xsource s shoul d tak e int o accoun t applicatio n o f th e sectio n 182(f ) RAC T an d NS Rrequirement s (a s par t o f th e areawid e baselin e condition s expecte d a t th e attainmen t deadlin e year ) sinc e thos e NOxreduction s ar e no t th e subjec t o f th e exemptio n request
.P.1 7

1 3 CHAPTE R4 CONTRIBUT E T O ATTAINMENT 4. 1 Demonstratio n Thi s demonstratio n applie s onl yt o ozon e nonattainmen t area s tha t ar e no t withi n a nozon e transpor t region
. Th e demonstratio n mus t sho wtha t additiona l NO xreduction s woul d no t contribut e t o ozon e attainmen t i n th e area . Th e procedur e fo r thi s tes t i s t o utiliz e a photochemica l gri d mode l (se e chapte r 7 ) t o simulat e severa l episod e case s ove r th e nonattainmen t are a unde r condition s tha t ma yb e expecte d a t th e attainmen t deadlin e (se e sectio n 8.2 ) considering thre e emissio n reductio n scenario s (se e sectio n8.3) : (1 ) substantia l VO C reductions ; (2 ) substantia l NOxreductions ; and (3 ) bot hth e VO C an d NO xreductions
. I f th e areawid e predicte d maximum 1-hou r ozon e concentratio n fo r eac hdaymodele d unde r scenari o (1 ) i s les s tha n o r equa l t o tha t fro mscenario s (2 ) and (3 ) fo r th e sam e day , the n th e tes t i s passe d an d th e sectio n 182(f ) requirement s woul d no t apply
. 4. 2 Episode s t o Conside r I n mos t ozon e nonattainmen t area s i t i s likel ytha t portion s o f th e are a woul d benefi t fro mNO xreduction s and othe r portion s woul d no t fo r eac hmodele d day
. Th e EPAbelieve s i t i s appropriat e t o focu s thi s analysi s o nth e areawid e maximu m1-hou r predicte d ozon e concentratio nsinc e thi s valu e i s critica l t o th e attainmen t demonstration
. I n contrast , i t shoul d no t b e necessaryt o examin e th e maximu m1-hou r ozon e concentration s a t eac hpoin t modele d i n th e are a sinc e thes e point s ar e no t necessaril yimportan t t o developmen t o f th e attainmen t demonstratio n an

d sinc e thi s i s th e onl yon e o f th e sectio n 182(f ) test s whic hi s no t keye d t o ne t benefits
. i i I n certai n ozon e nonattainmen t area s i t i s possibl e tha t NO xemissio n reduction s mayhel p t o reduc e th e areawid e maximu mpredicte d ozon e concentratio nunde r some meteorologica l condition s bu t no t unde r others
. Th e phras e "woul d no t contribut e t o attainment " coul d b e interprete d t o mea ntha t NO x emissio n reduction s woul d no t hel p reduc e (1 ) anyareawid e maximu m1-hour predicte d ozon e concentration , (2 ) th e majorit yo f areawid e maximu

m1-hour predicte d ozon e concentrations , o r (3 ) th e mos t sever e areawid e maximu m1-hour predicte d ozon e concentration
. Th e EPAbelieve s tha t th e "majority " optio ni s no t appropriat e sinc e thi s i s th e onl yon e o f th e sectio n 182(f ) test s whic hi s no t keye d t o ne t benefits
. Furthermore, - (1 ) a n are a maynee d t o demonstrat e attainmen t unde r multipl eP.1 8

1 4 meteorologica l conditions , (2 ) generall ya smal l numbe r o f episode s wil l b e modele d an d (3 ) th e NAAQ S i s base d o n multipl e exceedance s rathe r tha na single , mos t sever e value
. Fo r th e abov e reasons , EPAbelieve s thi s determinatio nshoul d b e base d o n eac hareawid e maximu m1-hour predicte d ozon e concentratio n modele d i naccordanc e wit hthi s guidanc e (chapte r 7)
. Thus , al l o f th e areawid e maximu m1-hour predicte d ozon e concentration s modele d mus t b e greate r wit hNO xreduction s a t th e source s concerne d tha n withou t th e reductions , o r n o exemptio nwoul d b e granted
. A n are a i s no t require d t o mode l al l pas t exceedances ; onl ythos e episode s selecte d fo r modeling i naccordanc e wit hEP A guidanc e (chapte r 7 ) nee d t o b e considered
. 4. 3 Geographi c Scop e Thi s demonstratio n focuse s o n attainmen t o f th e ozon e NAAQ S "i n th e area. " Th e EPAinterpret s thi s t o mean , a t a minimum , i n th e nonattainmen t area . I n contras t t o th e provisio nfo r transpor t regions , whic hi s likel yt o conside r severa l attainmen t an d nonattainmen t area s i n th e sectio n182(f ) analysis , thi s demonstratio ni s limite d t o consideratio n o f th e effect s i n a singl e nonattainmen t are a du e t o N0 Xemission s reduction s from source s i n th e same nonattainmen t area . However , sinc e th e effect s o f a n attainmen t strateg ymayextend beyond th e designate d nonattainmen t are a an d sinc e photochemica l gri d modelin g i s necessaryfo r thi s demonstratio n an d i s likel yt o us e a modelin g domai n large r tha n th e nonattainmen t area , EP A encourage s States/petitioner s t o includ e consideratio n o f th e entir e modelin g domain
. State s shoul d conside r impositio no f th e NO xrequirement s i f neede d t o avoi d advers e impact s i ndownwind areas , eithe r intra

o r inter-State
. State s nee d t o conside r suc himpact s sinc e the y ar e ultimatel yresponsibl e fo r achieving attainmen t i nal l portion s o f thei r Stat e (se e generall ysectio n110 ) and fo r ensuring tha t emission s originating i nthei r Stat e d o no t contribut e significantl yt o nonattainmen t in , o r interfer e wit h maintenanc e by , an yothe r Stat e [se e sectio n110(a)(2)(D)(i ) (I ) ]
. 4. 4 Applicabilit yt o Area s Requesting Redesignatio nt o Attainmen t I n som e cases , a nozon e nonattainmen t are a migh t attai n th e ozon e standard , a s demonstrate d b y3 year s o f adequat e monitorin g data , withou t having implemente d th e sectio n182(f ) NO x provision s ove r tha t 3-year period
. Wher e th e Stat e submit s a reques t fo r redesignatio n t o attainmen t along wit hnecessar y supportin g documentatio nan d wher e NOxRAC T an d NS Rrequirement s wer e no t implemente d ove r tha t 3-year period , i t i s clea r tha t th e sectio n 182(f ) languag e i s me t since."additiona l reduction s o f oxide s o f nitroge n woul d no t contribut e t o attainment. " Tha t is , sinc e attainmen t ha s alread yoccurred , additiona l NO xP.1 9

1 5 reduction s coul d no t improve th e area' s attainmen t statu s and , therefore , th e sectio n 182(f ) demonstratio ncoul d b e approved
. Additiona l guidanc e on thi s subjec t i s containe d i n a Septembe r 17 , 199 3 memorandu

mfro mMichae l Shapir o t o th e EP ARegiona l Office s regardin g request s fo r redesignatio nt o attainment
. Th e sectio n 182(f ) demonstratio nwoul d no t b e approve d i f ther e i s evidence , sucha s photochemica l gri d modeling , showing tha t th e NO xexemptio n woul d interfer e wit hattainmen t o r maintenanc e i n downwin d areas . A s note d above , sectio n11 0 prohibit s suc himpacts
.P.2 0

1 6 CHAPTE R5 NE T OZONE AI RQUALITYBENEFI T 5. 1 Demonstratio n Thi s demonstratio n applie s i n a nozon e transpor t region
. I t mus t sho wtha t additiona l N0 Xreduction s woul d no t produc e ne t ozon e benefit s i n th e transpor t region
. I nthi s tes t th e ne t benefi t mus t b e demonstrate d o na regionwid e basis
. Regionwid e include s al l portion s o f th e ozon e transpor t regio n i n whic h impact s fromNO xemission s fro m th e are a seeking th e exemptio n ca n b e determine d b yth e photochemica l gri d model
. Th e procedur e fo r thi s tes t i s t o utiliz e a photochemica l gri d mode l (se e chapte r 7 ) t o simulat e condition s tha t ma yb e expecte d a t th e attainmen t deadlin e (se e sectio n8.3 ) considerin g thre e emissio n reductio n scenario s (section 8.4) : (1 ) substantia l (s e sectio n 8.4 ) VO C reductions ; (2 ) substantia l NO x reductions ; and (3 ) bot hth e VO C an d NO xreductions
. Th e ne t ozon e benefi t mayb e determine d b ycomparing th e ozon e concentration s modele d i n scenari o (1 ) wit hresult s modele d from scenario s (2 ) an

d (3)
. I f th e exposur e t o ozon e concentration s fromscenari o (1 ) i s les s thano r equa l t o th e exposur e t o ozon e concentration s fromscenario s (2 ) an d (3) , the nth e sectio n 182(f ) ne t ozon e benefit s demonstratio n coul d b e approved
. A s describe d i n sectio n8.3 , multi-yea r analyse s mayals o b e conducted
. 5. 2 Factor s Th e ozon e NAAQ S i s se t a t 0.1 2 part s pe r millio n (ppm)
. I n definin g "ne t ozon e benefit,'. 1 however , EPArecognize d tha t variou s form s o f expressio n coul d b e considere d wit hrespec t t o ozon e impacts
. Thes e form s includ e th e 1-hour 0.1 2 ppmNAAQS , a 1-hour valu e les s tha n 0.1 2 ppm , a n8-hour valu e se t lowe r tha n 0.1 2 ppm , and a seasona l valu e se t lowe r tha nth e 0.1 2 ppmvalue
. However , ozon e concentration s wit hdifferen t averaging period s an d value s canno t readil yb e compare d t o eac hother
. Fo r example , i t i s difficul t t o compar e a se t o f 1-hour ozon e pea k concentration s abov e 0.1 2 pp magains t a se t o f 8-hour ozon e pea k concentration s abov e 0.0 6 an d determin e whic hresult s ar e mor e beneficial
. Th e EP Abelieve s i t i s reasonabl e t o focu s th e ne t ozon e benefit s tes t o nth e 1-hour 0.1 2 pp m ozon e NAAQS , wher e possibl e fo r th e followin g reasons : (1 ) th e 0.1 2 pp mozon e NAAQ S ha s bee n se t b yth e Administrato r a s th e leve l necessaryt o protec t th e mos t sensitiv e individual s fro madvers e healt heffect s wit han "adequat e margi n o f safety; " (2 ) ozon e concentration s wit h differen t averagin g period s an d value s canno t readil yb e compare d t o eac hother , (3 ) th e purpos e o f the variou s sectio n 18 2P.2 1

1 7 provision s i s primaril yt o attai nth e ozon e NAAQS , and (4 ) i t i s importan t fo r thi s guidanc e documen t t o avoi d anyconflict s (a s note d i n chapte r 3 ) wit hth e sectio n18 2 requirements
. Therefore , th e averaging tim e t o b e use d shoul d b e th e one-hou r dail ymaximu

mozon e concentratio n an d th e analysi s shoul d focu s o nvalue s abov e th e 0.1 2 ppmNAAQ S level
. Specifically , th e ne t ozon e benefit s tes t focuse s o n th e tota l geographi c are a expose d t o ozon e concentration s abov e th e 0.1 2 pp mNAAO S level
. Wher e Urba n Airshe d Mode l (UAM ) result s ar e available , populatio n exposur e t o concentration s abov e o r nea r th e ozon e NAAQ S ma yb e used , instead o f th e geographi c are a exposur e factor
. Th e Regiona l Oxidan t Mode l (ROM ) result s fo r NO x reductio nscenario s ove r majo r emissions/populatio n center s shoul d no t b e use d quantitativel yfo r populatio nexposur e analyses
. Thi s i s becaus e ROMresult s hav e thei r larges t associate d uncertaintie s i n area s wher e ther e i s a ninhomogeneou s mi xo f emission s frommajo r sources . Sinc e suc harea s als o ten d t o hav e greates t populations , us e o f th e ROM , b yitself , t o estimat e populatio n expdsur e mayhav e considerabl e associate d uncertainty
. Dependin g o nth e amoun t o f NO xan d VO C reduction s selecte d fo r eac hscenario , th e mode l result s i nsome case s migh t sho wal l scenario s t o b e belo wth e 0.1 2 ppmozon e NAAQ S level
. I n suc h case s some migh t argu e tha t ther e i s n o ozon e benefi t and , thus , th e NO xrequirement s shoul d no t apply
. Th e EP Adoe s no t agre e wit hsuc ha ninterpretatio nbecaus e th e CA Aspecifie s "ne t ozone " rathe r tha n "ozon e attainment " fo r thi s test
. I n fact , a "net " ozon e tes t i s necessaryt o integrat e th e benefit s an d disbenefit s o f NO xreduction s tha t ar e likel yt o varyfromgri d t o gri d i na give n analysi s area . Tha t is , NO xreduction s ma yreduc e hourl y ozon e concentration s i n som e location s an d increas e hourl yozon e concentration s i n othe r location s withi nth e same modelin g domain
. Therefore , a broade r facto r i s neede d tha nth e areawid e 0.1 2 ppmwher e th e modele d scenario s showal l value s belo wth e ozon e NAAQS
. i *

- ' Consideratio n o f ozon e ai r qualit yimpact s othe r tha nth e primaryNAAQ S value s i s appropriat e a s a secondaryfactor
. Thus , value s suc ha s th e following ar e appropriat e fo r consideratio n wher e n o conclusio n ca n b e draw nthroughth e abov e analysi s base d o nth e ozon e NAAQ S values : effect s associate d wit hlong-term exposure s t o ecosystems , crops , animals , an d materials
. 5. 3 Attainment/Unclassifie d Portion s Th e sectio n 182(f)(1)(B ) demonstratio nexplicitl yrefer s t o nonattainmen t area s withi n a n ozon e transpor t region
. Th e CA A doe s no t clearl ystat e whethe r o r no t portion s o f ozon e transpor t region s tha t ar e attainment/unclassifie d can mak e th e ne t ozon e benefi t demonstration
. Th e sectio n 182(f)(1 ) ne t ai r qualit y 

# JP.2 2

1 8 benefi t tes t i s availabl e t o an yarea ; however , a s note d previousl yi t i s a highe r hurdle
. Thus , whil e a severel y pollute d are a migh t b e abl e t o demonstrat e tha t NO xreduction s d o no t appl ybecaus e th e "ne t ozon e benefits " tes t i s satisfied , th e CA Acoul d b e interprete d t o requir e NO xreduction s i n th e surroundin g attainmen t are a becaus e tha t are a canno t mee t th e same test
. I t i s unlikel ytha t Congres s intende d suc ha result
. Analternativ e reading o f th e CA Aca n b e found throug h sectio n 184(b)(2)
. Thi s provisio nstate s tha t th e attainment / unclassifie d portion s o f th e transpor t regio nmus t mee t "th e requirement s whic hwoul d b e applicabl e t o majo r stationar y source s i f th e are a wer e classifie d a s a moderat e nonattainmen t area. " Thus , th e CA Acoul d b e interprete d t o provid e th e sam e sectio n 182(f)(1)(B ) demonstratio nproces s fo r thes e attainment / unclassifie d areas , sinc e theyshoul d b e treate d a s moderat e nonattainmen t area s fo r th e purpos e o f applying th e sectio n 182(f ) requirement s an d moderat e nonattainmen t area s i n th e transpor t regio n ar e eligibl e t o mee t th e "ne t ozon e benefits " test
. -''; ' Eve n withou t tha t language,'EPAwoul d b e incline d t o allo w a n attainment/unclassifie d are a i na transpor t regio nt o satisf y th e "ne t ozon e benefits " test
. I t woul d b e absurd , and therefor e i t i s unlikel ytha t Congres s intende d t o appl ymor e stringen t requirement s i n th e attainment/unclassifie d portion s o f th e transpor t regio n than woul d appl yt o th e mor e severel ypollute d portions
. Congres s apparentl ydi d no t intend an ylesse r requirement s t o appl yi nth e attainment/unclassifie d portion s o f th e transpor t region
. Th e EPAbelieve s tha t i t i s appropriat e t o extend th e sectio n 182(f ) provisio n beyond th e boundarie s o f a nonattainmen t are a int o adjacen t attainment/unclassifie d area s whic har e par t o f th e same sectio n182(f ) demonstration
. Thus , wher e a State/petitione r demonstrate s tha t NO xreduction s woul d no t produc e ne t ozon e benefit s i nth e transpor t region , the n th e sectio n 182(f ) NO xrequirement s woul d no t appl yt o thos e source s o r area s a s describe d i nEPA' s approva l action
. Suc ha demonstratio nmus t 'includ e al l portion s o f th e ozon e transpor t regio n i nwhic himpact s fromNO xemission s fromth e are a seekin g th e exemptio n ca n b e determine d b yth e photochemica l gri d model
.P.2 3

1 9 CHAPTE R6 EXCES S EMISSION S REDUCTION S 6. 1 Genera l Sectio n 182(f)(2 ) provide s th e flexibilit yt o limi t th e scop e o f th e NO xNS Rand RAC T requirements
. Applicatio no f th e NO xNS Rand/o r RAC T requirement s ca nbe
. limite d t o th e exten t tha t an yportio no f thos e reduction s ar e demonstrate d t o resul t i n "exces s reductions. " Th e test s fo r demonstratin g exces s reduction s ar e generall yth e same a s i nsectio n182(f)(1) : ne t ai r qualit ybenefit , contribut e t o attainmen t an d ne t ozon e benefit
. However , i n thi s case , th e demonstratio nmus t sho wtha t a portio n o f th e otherwis e require d NOxreduction s ar e eithe r counterproductiv e t o th e ne t ai r quality , d o no t contribut e t o attainment , o r d o no t provid e a ne t ozon e benefi t [dependin g o n th e sectio n182(f ) tes t applied]
. A s describe d below > fo r th e contribut e t o attainmen t o r ne t ozon e tests , th e exces s reduction s tes t mus t sho wtha t certai n NO xreduction s ar e i nexces s of;th e reduction s specifie d i n eithe r th e attainmen t demonstratio nrequire d b ysectio n18 2 and containe d i n th e approve d SI P o r a nattainmen t demonstratio n adopte d b

yth e Stat e t o mee t th e sectio n 18 2 attainmen t demonstratio n requiremen t and submitte d t o EPAfo r approval
. Th e exces s emissio nreduction s ma yb e described , fo r example , a s (1 ) an areawid e across-the-boar d tonnag e reduction ; (2 ) emission s attribute d t o specifi c sources ; o r (3 ) emission s from a geographi c portio n o f th e nonattainmen t o r transpor t area . 6. 2 Demonstratio n Th e "contribut e t o attainment " an d "ne t ozon e benefit " test s describe d i n chapter s 4 an d 5 bot hrequir e an areawid e o r regiona l analysis
. I nsuc hareawide/regiona l analyses , NO x emissio n reduction s ta t a larg e numbe r o f source s ar e considered
. Thes e analyse s ar e appropriat e t o determin e i na directiona l manne r whethe r o r no t NO xreduction s ar e expecte d t o b e beneficia l wit hrespec t t o th e ai r qualit yi nth e area/region
. Th e analyse s describe d i n chapter s 4 an d 5 mayb e les s precis e than a n attainmen t demonstratio n require d unde r sectio n 182(c)
. Th e EPAbelieve s tha t th e exces s reduction s provisio n require s a mor e precis e analysis ; specificall ya nanalysi s whic h i s base d o n th e attainmen t demonstration
. Tha t is , th e exces s reduction s provisio n mus t b e mor e thana directiona l findin g o n an areawid e basis
. Unde r th e exces s reduction s provision , a n analysi s i s neede d t o showtha t a specifi c portio no f th e tota l areawid e NO xemission s i s no t beneficia l unde r on e o f th e thre e tests
. Thus , individua l o r group s o f source s maypetitio nt o showthat , whil e NO xreduction s mayb e beneficia l directionall yP.2 4

2 0 i nth e area , NO xreduction s fromthei r specifi c source s ar e no t beneficia l and , thus , shoul d b e exemp t fromth e NO xrequirements
. Withou t providing some constraint s i nthi s guidanc e document , th e exces s reduction s provision s coul d undermin e th e sectio n 182(f ) requirements , sinc e eac hindividua l emissio n sourc e coul d theoreticall ypetitio nfo r a nexemptio n wit hth e argumen t tha t thei r smal l contributio nt o th e overal l ozon e proble mi s inconsequential
. Suc ha petitio nmigh t b e considere d consisten t wit hth e analyse s require d i nchapter s 4 and 5 , sinc e a n exemptio nmayb e grante d wher e th e modele d NO xreduction s sho w n o impac t o n ozon e concentrations
. Certainly , i f EPAallowe d ver ysmal l amount s o f NO xreduction s t o b e modele d individually , thi s interpretatio nwoul d creat e a significan t loophole
. Congres s woul d no t hav e intended , and therefor e EP Adoe s no t accep t th e argument , tha t th e owner/-opera to r o f on e ca r o r on e smal l boile r ca n b e excuse d from th e CA Arequirement s becaus e thei r emissions , - viewe d alone , ar e small
. Considere d togethe r wit hothe r smal l contributions , th e emission s ma yb e importan t t o attainment
. Tha t is , emission s fro m on e ca r o r on e commercia l boile r woul d no t change--th e areawid e ozon e concentration , ye t togethe r wit hothe r car s o r boilers , the ymayb e critica l t o th e area' s attainmen t strategy
. Furthermore , a s previousl y describe d i n thi s document , ozone , ai r qualit ymodel s shoul d no t b e applie d solel yt o determin e th e incrementa l effec t o f smal l source s a s suc hemission s coul d b e los t i nth e nois e o f th e ai r qualit ymode l an

d emission s inventoryuncertaintie s whe n considere d alone
. Fo r th e abov e reasons , EPAha s determine d tha t th e exces s reduction s demonstratio nfo r th e "contribut e t o attainment " o r "ne t ozon e benefits " test s mus t b e tie d t o th e area' s SI P attainmen t demonstration
. Thus , thi s tes t mus t sho wtha t th e exces s reduction s ar e reduction s i nexces s o f thos e specifie d i n th e attainmen t demonstratio nrequire d b ysectio n18 2 and eithe r containe d i n th e approve d SI P o r a s adopte d b yth e Stat e t o mee t th e sectio n18 2 attainmen t demonstratio nrequiremen t and submitte d t o EPAfo r approval
. Thi s ti e t o th e attainmen t demonstratio n assure s tha t a nexces s reduction s petitio n woul d no t arbitraril yb e base d o nsmal l emission s an d woul d no t undermin e th e State' s contro l strategy
. I n contrast , th e "ne t ai r qualit ybenefit " tes t discusse d i n chapte r 3 i s intende d t o addres s an individua l o r smal l numbe r o f source s and alread yha s anadequat e constraint
. Th e ne t ai r qualit ybenefi t tes t require s a showing tha t NO xreduction s specificall yfromth e source s concerne d ar e counterproductive
. Th e ne t ai r qualit ybenefi t tes t impose s a highe r hurdl e tha n th e othe r tw o test s an d EPAbelieve s thi s highe r hurdl e i s adequat e fo r purpose s o f th e exces s emission s tes t a s well
.P.2 5

2 1 CHAPTE R7 MODELINGTECHNIQUE S 7. 1 Photochemica l Gri d Modelin g A s describe d i n chapter s 3-6 , photochemica l gri d modelin g i s generall yneede d t o documen t case s wher e NO xreduction s ar e counterproductiv e t o ne t ai r qualit y(chapte r 3) , d o no t contribut e t o attainmen t (chapte r 4) , d o no t sho wa ne t ozon e benefi t (chapte r 5) , o r includ e exces s reduction s (Chapte r 6 )
. A s describe d below , th e Urba n Airshe d Mode l (UAM ) or , i n a nozon e transpor t region , th e Regiona l Oxidan t Mode l (ROM ) ar e acceptabl e model s fo r thes e purposes . Th e EPAinvestigate d th e feasibilit yan d acceptabilit yo f applying relativel yinexpensiv e screening technique s t o evaluat e i f NO xcontro l measure s ar e likel yt o b e beneficia l wit hrespec t t o attainmen t o f th e ozon e NAAQ S (Langstaf f an d Scheffe , 1991)
. However , EPAdetermine d that , a s a technica l matter , photochemica l gri d modelin g i s th e onl yreliabl e too l t o justif y a n areawid e exemptio n fromth e NO xrequirements
. Th e EPA' s relianc e o n photochemica l gri d model s i s supporte d b yth e recentl ypublishe d finding s o f th e NA S o ntropospheri c ozon e (Decembe r 1991)
. Th e NA S repor t conclude d tha t three

dimensiona l o r grid-base d ozon e ai r qualit ymodel s ar e currentl y th e bes t availabl e model s fo r representing th e chemica l and physica l processe s o f ozon e formation
. Th e repor t provide s a lis t o f suc hmodel s (Tabl e 10-1) , including UA Man d ROM
. Th e NA S repor t als o state s tha t "ROMi s th e onl yregiona l mode l availabl e fo r assessmen t o f contro l strategie s fo r urba nan d rura l ozon e i n th e easter n Unite d States " (page 365)
. Th e 199 0 CA

Arequire s th e us e o f gridde d model s i nmany ozon e nonattainmen t areas . I n 1990 , EPArelease d a nupdate d versio n o f th e UAM > (reflectin g numerou s advance s i n photochemistryan

d ^numerica l solutio ntechnique s whic hemerge d during th e 1980s
. An extensiv e multi-volume UA MUser' s Manua l wa s prepare d t o facilitat e operatio no f th e UAM
. Guidanc e o n regulatoryapplicatio n o f th e UA Mwa s complete d i nJul y1991
. Severa l effort s ar e underwayt o improve pre - an d post-processin g UA Mcapabilitie s an

d trai n th e State s i napplying th e model
. Th e EPAencourage s application s o f advance d modelin g method s wher e the yar e foun d t o b e mor e appropriate
. Suchmethod s ma yb e acceptabl e o n a case-by-cas e basi s afte r (1 ) preparatio n o f a modelin g protocol , (2 ) prope r testing an d evaluation , and (3 ) approva l b

yth e appropriat e EPARegiona l Office
. Les s sophisticate d models , suc ha s EKMA , lack th e detaile d treatment/consideratio n o f physica l orientatio no f NO xsource sP.2 6

2 2
an d dispersio n o f thei r plumes
. Further , sinc e trajectorymodel s onl yaddres s a limite d numbe r o f trajectories , the ycanno t asses s whethe r NO xcontro l contribute s t o attainmen t a t al l location s i n a nozon e nonattainmen t area. ' Therefore , suc hmodel s ar e insufficien t and no t acceptabl e fo r th e sectio n 182(f ) demonstration
. 7. 2 Urba n Airshe d Mode l UA Mresult s ar e acceptabl e fo r th e purpos e o f th e sectio n 182(f ) demonstrations
. Applicatio no f UA Mshoul d b e consisten t wit htechnique s specifie d i n th e EPA"Guidelin e o nAi r Qualit y Model s (Revised).' 1 Further , applicatio n o f UA Mshoul d als o b e consisten t wit hprocedure s containe d i n th e EPA"Guidelin e fo r RegulatoryApplicatio no f th e Urba nAirshe d Model " (Jul y1991)
. Thus , episod e selectio n fo r th e sectio n 182(f ) demonstratio n shoul d b e consisten t wit hth e UA Mguidanc e fo r SI P attainmen t demonstrations
. A n assessmen t o f th e model' s performanc e and a copyo f th e modelin g protoco l shoul d b e include d i n th e analysi s fo r informationa l purposes . 7. 3 Regiona l Scal e Modelin g I n a n ozon e transpor t region , th e ne t ozon e benefit s tes t shoul d b e me t byus e o f regiona l scal e modeling
. Regiona l scal e modeling i s neede d sinc e th e sectio n 182(f ) languag e explicitl y refer s t o ne t ozon e benefit s "i nsuchregion. " Regionwid e o r regiona l scal e modelin g include s al l portion s o f th e ozon e transpor t regio n i n whic himpact s fro mNOxemission s fromth e are a seeking th e exemptio nca nb e determine d b yth e photochemica l gri d model
. Prio r t o th e availabilit yo f RO Mand/o r UA Mresult s supporting th e sectio n 182(c ) attainmen t demonstrations , th e EPA' s "Regiona l Ozon e Modeling fo r Northeas t Transport " study (June 1991 ) i s a n acceptabl e basi s fo r thi s demonstration
. Whe n mor e recen t RO Mand/o r UA Mregionwid e studie s fo r th e Northeas t Ozon e Transpor t Regio n hav e bee n complete d an d ar e available , theymus t b e use d fo r an ysectio n182(f ) demonstration
. Wher e UA

Mstudie s hav e bee n complete d an d ar e available , RO M result s ar e acceptabl e fo r evaluating effect s outsid e o f th e UA M modeling domain s establishe d pursuan t t o attainmen t demonstratio n requirement s fo r sectio n 182
. Thus , ROMresult s ar e acceptabl e fo r evaluatin g effect s i n portion s o f a transpor t regio noutsid e o f th e UA

Mmodelin g domai n fo r th e purpos e o f a sectio n182(f ) demonstration
. I t i s no t appropriate , however , t o us e RO Mt o asses s th e effect s i n an individua l cit youtsid e o f an yUAM domain
. RO Mi s mos t suitabl e fo r assessing composit e impact s ove r larg e area s (whichmayinclud e individua l cities ) wher e UA M result s ar e unavailable
. Result s o f availabl e ROMapplication s ar e archive d o n th e EPA' s Gridde d Mode l Informatio n Suppor t System(GMISS)
.P.2 7

2 3 7. 4 Mode l Result s an d SI P Interfac e Wher e a petitio n fo r a n exemptio n [sectio n182(f)(1) ] o r exces s reduction s determinatio n [section 182(f)(2) ] i s grante d b y EPAprio r t o adoptio nan d submittal " o f th e State' s rules , th e Stat e ma ysimpl ychoos e no t t o submi t th e NO xrules
. I f a petitio n i s grante d afte r submitta l o f th e NO xrules , bu t prio r t o EP Aapproval , th e Stat e ma ychoos e t o withdra wth e rule s and preclud e furthe r EPAaction
. I na cas e wher e a petitio ni s grante d ("exempted area" ) afte r EPAapprove s o f th e N0 Xrules , th e SI P woul d nee d t o b e modifie d througha SI P revisio n t o . rescind th e N0 Xrule s provide d suc hrescissio nwoul d no t interfer e wit hattainmen t o r reasonabl e furthe r progres s [sectio n 110(1)]
. Followin g applicatio n o f a photochemica l gri d mode l tha t i s require d fo r seriou s an d abov e area s t o suppor t th e attainmen t demonstration s du e b yNovembe r 1994 , a Stat e mus t selec t and adop t a contro l strateg ytha t provide s fo r attainmen t a s expeditiousl ya s practicable , bu t n o late r tha n th e dat e prescribe d i nsectio n 181
. Thi s decisio nmus t b e addresse d bya Stat e whethe r o r no t a n are a wa s exempte d fromth e Novembe r 199 2 submitta l o f NO xRAC T and/o r NS Rrule s an d mayresul t i nrevisio n o f th e previousl yadopte d rules
. I n some instance s th e NO xRAC T an d NS Rrequirement s alread yadopte d maynee d t o b e supplemente d wit hadditiona l o r mor e advance d N0 Xcontrol s i norde r fo r th e are a t o attai nth e NAAQS
. I n othe r cases , an are a initiall yexempte d ma ychoose , base d o n th e ne wphotochemica l gri d modeling results , t o adop t certai n N0 Xreductio n rule s i n orde r t o attai n and/o r mee t reasonabl e furthe r progres s requirement s throughN0 Xsubstitution
. Th e are a woul d b e remove d fro m"exempt " statu s sinc e NO xreduction s wer e subsequentl yfound t o b e beneficia l i n thei r ozon e attainmen t plan
. Consequently , th e are a woul d hav e t o adop t th e NO xRAC T an d NS Rrule s excep t t o th e exten t modeling show s tha t th e control s beyond thos e chose n ar e "exces s reductions " (chapte r 6 ) o r ar e counterproductiv e t o th e ne t ai r qualit y(chapte r 3 )
. Credi t fo r NO xsubstitutio nwoul d b e grante d onl yi f i n accordanc e wit hth e EPAguidance
. I n an yevent , thes e change s mus t b e submitte d a s a SI P revisio nan d mus t provid e fo r attainmen t a s expeditiousl ya s practicabl e an d mee t reasonabl e furthe r progres s requirements
. Alternatively , fo r anare a tha t adopte d th e NO xRAC T and NS R rule s a s require d b ysectio n 18 2 (i.e. , no t exempt) , a Stat e ma y choos e t o revis e some o r al l o f thos e rule s t o requir e les s NO x stationarysourc e controls
. Thi s actio nwoul d b e base d o n th e applicatio n o f a photochemica l gri d mode l showing tha t th e subjec t NO xcontrol s resul t i nexces s emissio n reductions , a s determine d usin g th e sectio n 182(f ) test s se t fort ha t th e beginnin g o f thi s section
. Th e revision s mus t b e submitte d a s aP.2 8

2 4 SI P revisio n and th e SI P mus t demonstrat e attainmen t a s expeditiousl ya s practicable
. 7. 5 Othe r Analytica l Technique s Guideline s o n analytica l technique s fo r assessing othe r ai r qualit yimpac t factors , suc ha s aci d deposition , populatio n exposur e o r visibility , ar e no t readil yavailable
. Therefore , EPAencourage s petitioner s t o consul t wit hth e Stat e and EP A Regiona l Offic e t o agre e o n a nacceptabl e methodologyo na case by-cas e basis
.P.2 9

2 5

. CHAPTE R8 EMISSION S ANALYSI S 8. 1 Genera l A s describe d i n chapter s 3-6 , photochemica l gri d modelin g i s neede d t o documen t case s wher e NO xreduction s ar e counterproductiv e t o ne t ai r qualit y(chapte r 3) , d o no t contribut e t o attainmen t (chapte r 4) , d o no t sho wa ne t ozon e benefi t (chapte r 5) , o r includ e exces s reductions.(chapte r 6)
. Applicatio n o f thes e model s require s th e us e o f a representativ e emission s inventory
. Thi s chapte r describe s th e emissio n inventoryrequirement s fo r th e variou s sectio n182(f ) demonstrations
. 8. 2 Biogeni c Volatil e Organi c Compoun d (VOC ) Emission s Th e NA S repor t state s that , i nsome cases , "withou t contro l o f NO xemissions , this-VO C backgroun d shoul d b e abl e t o generat e ozon e concentration s tha t excee d th e NAAQ S concentratio n o f 12 0 ppb " (pag e 244 )
. Biogeni c emission s ca ninfluenc e bot hth e natur e (i.e. , VO C o r NOx ) an d exten t o f require d emission s controls
. Therefore , inclusio n o f biogeni c emission s ar e necessaryinput s t o mode l application s whic hasses s th e role s o f VO C and NO xi nozon e formatio nfo r purpose s o f sectio n182(f)
. I nestimatin g biogeni c emissions , th e mos t recen t versio no f th e Biogeni c Emission s InventorySystem (BEIS ) (availabl e throug hth e EPARegiona l Offices ) shoul d b e used
. 8. 3 Year s t o Analyz e I n general , th e purpos e o f th e sectio n182(f ) requirement s fo r NO xi s relate d t o attainmen t o f th e ozon e standard
. Thi s suggest s a nanalysi s tha t i s focusse d o n th e tim e tha t attainmen t o f tha t standar d i s required
. I n addition , othe r section s o f th e CA Arequir e moderat e an d abov e ozon e nonattainmen t area s t o develo p modelin g analyse s whic hdemonstrat e attainmen t b yth e appropriat e statutorydeadline ; t o th e exten t tha t suc hmodelin g analyse s ar e alread yunderway , theycoul d b e usefu l fo r th e sectio n 182(f ) demonstratio n also
. Considerin g thes e points , EP Abelieve s tha t th e 182(f ) demonstration s should , a t a minimum , reflec t condition s expecte d a t th e tim e th e subjec t are a i s require d t o attai n th e ozon e standard
. Fo r example , i n a seriou s ozon e nonattainmen t area , th e yea r woul d b e 1999
. A s describe d i nsectio n 8.5 , th e condition s shoul d als o b e consisten t wit hassumption s containe d i n th e SIP
. Thus , bas e yea r emission s woul d b e projecte d t o th e yea r reflectin g th e attainmen t deadlin e an d woul d includ e growt h i n VO C and NO xemission s a s wel l a s CAA-mandate d VO C emissio n reductions
. Specifi c emissio nscenario s wit han d withou t NO xP.3 0

2 6 reduction s woul d b e buil t upo n thi s projecte d emission s baselin e a s describe d elsewher e i nthi s document
. I naddition , a s describe d late r i nthi s section , multi-yea r analyse s ma yals o b e conducted
. I n a n ozon e transpor t region , a sectio n182(f ) demonstratio n woul d likel ycove r a n are a whic hinclude s ozon e nonattainmen t area s o f mor e tha n on e classification , an d thu s mor e tha n on e attainmen t deadline
. Fo r example , a . metropolita nare a ma yhav e a highe r classificatio n tha n a nearb yrura l nonattainmen t area . Fo r thes e areas , i t i s possibl e tha t NO xreduction s ma yb e beneficia l t o attainmen t i n th e nea r termwit hrespec t t o th e rura l nonattainmen t are a (an d lesse r classificatio ndeadline ) but , a t th e sam e tim e o r i n a longe r timeframe , NO xreduction s migh t b e shown t o b e no t beneficia l whe n considering th e are a a s a whol e (sinc e NO xreduction s ar e generall yexpecte d t o b e mor e beneficia l i n rura l areas)
. I n orde r t o determin e whethe r th e NO xreductio n requirement s shoul d apply , EPAbelieve s that , a t a minimum , th e sectio n 182(f ) demonstratio nshoul d reflec t condition s expecte d a t th e lates t attainmen t deadlin e fo r th e are a a s a whole
. I n addition , State s shoul d conside r impositio n o f th e NO xrequirement s i f neede d t o avoi d advers e impact s i n downwind areas , eithe r intra

- or.inter-State
. State s nee d t o conside r suc himpact s sinc e the yar e ultimatel yresponsibl e t o provid e fo r attainmen t i nal l portion s o f thei r Stat e and mus t no t contribut e significantl yt o nonattainmen t in , o r interfer e wit hmaintenanc e by , an yothe r State
. Alternatively , th e State/petitione r mayinclud e a multi-yea r analysi s i n it s sectio n 182(f ) demonstration
. Thi s i s appropriat e fo r area s demonstrating eithe r a ne t ai r qualit y benefi t o r a ne t ozon e benefit
. I n thes e demonstrations , th e analysi s mayinclud e periodi c assessment s o f th e effect s o f NO x reduction s and integrat e thos e effect s t o arriv e a t a finding o n whethe r o r no t NO xreduction s ar e beneficial
. Fo r example , a n are a maydevelo p geographi c are a exposur e analyse s fo r eac hyea r o r fo r everythir d -yea r up t o th e attainmen t yea r and asses s th e overal l impac t o f NO xreduction s fro mtha t information
. 8. 4 Scenario s t o Compar e Fo r th e contribut e t o attainmen t an d ne t ozon e benefi t tests , th e projecte d emission s should , a t a minimum , conside r thre e scenario s whic hvaryemissio nreduction s from anthropogeni c sources : (1 ) substantia l VO C reductions ; (2 ) simila r NO x reductions ; and (3 ) bot hth e VO C an d NO xreductions
. Tota l emission s t o mode l includ e bot hanthropogeni c an d biogeni c emissions
. I n contras t t o th e ne t ai r qualit ydemonstratio n (chapte r 3 ) whic hfocuse s o nth e scenari o "i n th e absenc e o f reduction s o f oxide s o f nitroge n fro mth e source s concerned, " th e contribut e t oP.3 1

2 7 attainmen t and ne t ozon e benefi t demonstration s concer n a n unspecifie d "additiona l reductions " o f NOx
. Thus , whil e th e ne t ai r qualit ybenefi t tes t mus t focu s o nNO xreduction s du e t o NS R an d RACT , th e othe r demonstration s maymor e broadl yconside r NO x reductions , including reduction s tha t emplo yadvance d contro l technology(i.e. , beyond RACT)
. Th e applicatio n o f th e VO C and NO xreduction s shoul d b e a s sourc e categoryspecifi c a s possible , rathe r tha n across-the-board , i norde r fo r th e result s t o b e mos t useful
. I nth e firs t scenari o th e demonstratio nshoul d us e th e VO C reduction s neede d t o attai n(demonstrate d byEKM Ao r UA M analyses)
. Alternatively , i f th e attainmen t demonstratio n ha s no t bee n completed , th e demonstratio n ma yus e some othe r substantia l VO C reduction
. Reduction s associate d wit hattainmen t ar e appropriat e fo r th e reason s describe d above
. I nan ycase , th e VO C reduction s shoul d b e substantia l an d documente d a s reasonabl e t o expec t fo r th e are a du e t o th e CA Arequirements
. Fo r example , a minimu m o f a 40 % anthropogeni c VO C reductio n areawid e fromth e 1990-emissio n inventoryma yb e reasonabl e t o expec t fo r seriou s areas , considering moto r vehicl e emissio n controls , inspection/maintenance , reasonabl e furthe r progres s an d othe r CA

Arequirements
. I n th e second scenario , NOxreduction s shoul d b e modele d withou t anyVO C reduction s above th e attainmen t yea r baseline
. Th e leve l o f NO xreduction s shoul d reflec t th e sam e percen t reductio n o f anthropogeni c VO C emission s i nscenari o (1 ) above
. I t i s importan t t o mode l thi s cas e sinc e NO xreductions , instea d o f additiona l VO C reductions , mayshowa cleare r benefit
. I n th e thir d scenario , a simila r leve l o f NO xreduction s woul d b e modele d along wit hth e leve l o f VO C reduction s chosen
. Tha t is , i f a 40 % VO C reductio n i s chose ni nscenari o (1 ) , the n th e mode l fo r scenari o (3 ) woul d simulat e a 40 % VO C reductio nand approximatel ya 40 % NOxreduction
. I t woul d b e inappropriat e t o selec t a hig hlevel,o f VO C reduction s an d a lo wleve l o f NO x reduction s sinc e thi s coui d artificiall yfavo r a finding tha t NO x reduction s ar e no t beneficial ; th e two level s shoul d b e similar
. 8. 5 Consistenc ywit hth e SI P Anysectio n 182(f ) demonstratio n mus t includ e a showin g tha t th e exemptio n reques t use s assumption s tha t ar e consisten t wit h requirement s o f th e SI P an d the CAA
. I t i s possibl e tha t a petitio n coul d demonstrat e that , unde r some circumstances , NO x reduction s ar e no t neede d t o attai nth e ozon e standard
. However , unles s th e Stat e actuall yadopt s thos e particula r circumstance s int o it s SIP , ther e i s n o assuranc e tha t th e petition' s analysi s i s valid
. Tha t is , i f th e assumption s containe d i nth e petitioner' s demonstratio n ar e no t valid , th e conclusion s ar e similarl yno t vali d an d EPAwoul d no t approv e th e petition
. Th e sectio n 182(f ) petitio n proces s shoul d no t undermin e th e State' sP.32
.

2 8 implementatio n plan
. Th e petitio n shoul d reflec t measure s consisten t wit hmandatoryCA Arequirements , federally-approve d SI P requirements , an d recen t SI P revision s adopte d b yth e stat e an d submitte d t o EPAfo r approval
. Th e EPAencourage s petitioner s t o coordinate•thes e analyse s wit hth e appropriat e State(s ) a s the yar e bein g developed
. 8. 6 Ne wSourc e Revie w Th e sectio n 182(f ) exemptio nprovision s cente r o n th e effec t o n ozon e concentration s du e t o NO xemissio nreductions
. Wit h respec t t o RACT , whic hinvolve s emission s reduction s from existing sources , thi s i s a perfec t fit
. I nth e cas e o f ne wo r modifie d sources , however , othe r factor s shoul d b e considered
. Eve n afte r th e applicatio no f on-sit e control s appropriat e fo r a majo r ne wo r modifie d source , th e sourc e will , considere d alone , resul t i n majo r increase s i n NO xemissions
. However , th e NS R offse t provision s woul d requir e th e ne wsourc e t o obtai nemissio n reduction s fro

mothe r source s s o a s offse t an yemission s increas e associate d wit hth e ne wsource . T o tak e int o accoun t th e ful l impac t o f th e NS Rprogram , th e ter m"NOxreductions " mus t b e carefull yinterpreted
. Whe n considering th e ai r qualit yimpact s i nchapter s 3- 6 o f thi s documen t "wit hNO xreductions " o r wit h"substantia l NO x reductions, " th e analysi s shoul d reflec t a zer o emission s increas e fromstationarysource s afte r Novembe r 15 , 199 2 du e t o th e NS Roffse t requirement ; whe nconsidering th e "without " NO x reduction s scenarios , th e analysi s shoul d includ e NOxemissio n increase s afte r Novembe r 15 , 199 2 du e t o ne wo r modifie d stationarysource s o f NOx , manyo f whic hwoul d b e subjec t t o th e bes t availabl e contro l technologyrequiremen t throughth e preventio n o f significan t deterioratio n program , bu t no t t o offsets
.