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# O J

DEVELOPMEN T O F OZON E REACTIVIT YSCALE S FORVOLATIL E ORGANI C COMPOUND S

Willia mP . L . Carte r Statewid e Ai r Pollutio n Researc h Cente r

Universit yo f Californi a Riverside , CA9252 1

MNS-90:scale sP. 3

Abstrac t

Mode l calculation s o f effect s o f ove r 14 0 type s o f volatil e organi c compound s (VOCs ) o n photochemica l ozon e formatio n i n a se t o f 6 2 idealise d airshe d scenario s representin g 1 2 differen t urba n area s wer e employe d t o investigat e alternativ e method s fo r developin g VO C reactivit yscales . Severa l method s fo r combinin g th e widely^varyin g reactivitie s fo r th e scenario s wer e use d t o deriv e variou s "aggregate d bas e case " reactivit y scales . Th e result s varie d dependin g o n th e aggregatio n metho d use d and ho wozon e impact s wer e quantified
. Sinc e th e mai n reaso n fo r thi s variabilit yi s th e dependenc e o f reactivitie s o n N0 X , a "maximum reactivity " scai e wa s derive d b yaveragin g reactivitie s whe n N0 Xinput s
ar e adjuste d s o VOC s hav e chei r greates t impac c o n ozone , an d a "maximum
ozone " reactivit yscal e wa s derive d b yadjustin g N0 Xinput s t o yiel d maximu mozon e concentrations
. Thes e tw o scale s ha d significan t difference s i n relativ e reactivities
. However , th e maximu mreactivit y scai e corresponde a reasonabl ywel l wit h th e aggregate d bas e cas e scaie s wher e ozon e impact s ar e quantified ' Dy , integrate d ozon e concentration , o r wher e th e aggregatio n metho d take s int o accoun t th e magnitud e o f th e effec t o f th e VO C o n ozone. I t i s conclude d tha t fo r ch e nea r ter mth e maximu m reactivit yscal e mayb e mos t appropriat e fo r application s wher e a singl e VO C reactivit yscal e i s applie d t o a wid e variet yo f airsheds
. Uncertaintie s i n tn e atmospheri c chemica l mechanism s fo r th e VOC s affec t thes e reactivit yestimates , an d qualitativ e ranking s o f mechanisti c uncertaintie s ar e give n fo r eac h VOC .P. 4

INTRODUCTIO N

Th e formatio no f photochemica l ozon e continue s t o be a nintractabl e problem inman y

urba nareas . Ozon e i s no t emitte ddirectl y int o the atmosphere , i t i s forme do y th e interaction s o f volatil e organi c compound s (VOCs ) wit hoxide s o f nitroge n(N0 X ) i nsunlight , an

deffectiv e ozon e contro l strategie s mus t focu s o nbot ho f tnes e precursors . However , i n urba narea s wher e NO. , source s ar e abundan t anddifficul t t o control , VOC contro l i s th e strateg y receivin g the mos t attention , a t leas t for th e
nea r term . Sinc e reductio no f tota l VOC emission s fro m mos t o f the majo r
source s i s difficul t an dcostly , strategie s involvin g changin g th e chemica l natur e o f VO C emission s s o tha t chey hav e les s o f a cendenc y c o promot e ozon e formation , i.e. , s o tha t che y ar e les s "reactive" , ar e becomin g increasingl y attractive . Two example s o f thi s i s conversio no f moto r vehicle s t o alternativ e fuel s suc ha s methanol , andth e substitutio n
o f currentl y

use dsolvent s wit hles s reactiv e compounds . Th e developmen t
an dassessmen c o f suc hstracegie s require s a mean s c o quantif y an dcompar e th e ozon e formatio nreactivitie s o f the man y type s o f VOC s whic hca nb e emitted . Ther e ar e a numbe r o f way s t o quantif y th e reactivitie s o f VOCs . Example s includ e th e rat e a t whic hanorgani c react s wit hhydroxy l radical s (th e mai natmospheri c reactio npathwa y for mos t organic s [Atkinson , 1989,1990] ) (Darnal l e t al. , 1976 ; ARB , 1989 ) andth e amoun t o f
ozon e th e organi c form s whe nirradiate di nN0 X- ai r mixture s in environmenta l chamber s (Wilsonan dDoyle , 1970 ; Altshulle r andBufalini , 1971 ; Lait y

e t al. , 1973) . However , fo r mos t contro l strateg y applications , whic har e concerne dwit hth e effect s o f incrementa l change s 

## yyP. 5

inemission s int o already pollute dareas , th e mos t usefu l measur e o f reactivit y

i s "incrementa l reactivity" . Thi s i s th e chang e inozon e
cause db

y th e additio no f the organi c ina standar dscenari o representin g
a nai r pollutio nepisode , normalize db y th e amoun t o f organi c added . Reactivit y

measure dinthi s wa y take s int o accoun t no t onl y the effect s o f al l aspect s o f th e organic' s reactio nmechanism , bu t als o th e effect s o f th e environmen t int o whic hi t i s emitted , whic hingenera l wil l influenc e ho w muc hozon e th e emissio no f an y organi c woul dcause . Th e incremental reactivitie s o f VOC s hav e bee ninvestigate d experimentall y

(Carte r an

dAtkinson , 1987 ) andinsevera l compute r modelin g studie s (Bufalin i an dDodge , 1983 ; Dodge , 1984 ; Houg hand Derwent , 1987 ; Carte r 1989a , 1989b ; Wei r e t al , 1988 ; Carte r andAtkinson , 1989) . Th e result s o f thes e studie s indicate dtha t mechanisti c an d environmenta l factor s ar e indeed importan t inaffectin g incrementa l reactivitie s o f organi c compounds . Th e mos t importan t singl e mechanisti c facto r affectin g a VOC s reactivit y i s the rat e a t whic hi t react s i nth e atmosphere . However , th e oche r aspect s o f it s reactio nmechanis m i s als o importan t andcanno t be ignored . Th e mos t importan t singl e environmenta l facto r i s th e availabilit y o f N0 Xi

nthe system , whic hi s mos t convenientl y

measure db

y th e rati o o f tota l emission s o f reactiv e organic s (ROG ) t o N0 X . Ingeneral , organi c compound s ar e foundt o hav e the highes t effect s o nozon e formatio nunde r relativel y hig hN0 Xcondition s (i.e. , lo w ROG/NO v ratios) , andt o hav e muc hlower , insome case s eve nnegative , reactivitie s unde r condition s wher e N0 Xi s limite d(hig hR0G/N0 X ratios) . Thi s i s becaus e unde r relativel y hig hN0 Xcondition s the amoun t
o f ozon e forme di s determine db y th e level s o f radical s forme dfro m th e reaction s o f th e VOCs , whil e unde r lowe r N0 Xcondition s th e availabilit yP. 6

o f N0 X , whic hmus t be presen t inorde r fo r ozon e t o be formed , limit s
ozon e formation . Othe r aspect s o f the environmen t i nwhic hth e VO C i s emitted , suc ha s natur e o f the othe r organic s emitte dint o th e airshe d (Wei r e t al. , 1988) , th e amoun t o f dilutio noccurrin g (Carte r an d Atkinson , 1989) , etc., ca nals o b e importan t i naffectin g VO C reactivities , thoug hinvestigation s o f thes e aspect s ar e limited . Th e dependenc e o f VO C reactivitie s o nenvironmental condition s present s problem s t o th e developmen t o f a genera l VO C reactivit y scal e for th e assessmen t o f ozon e contro l strategie s involvin g VO C substitutions . Th e mos t scientificall y justifiabl e approac hwoul dbe no t t o us e a genera l reactivit y

scale , bu t instea dt o carr y ou t detaile dmode l calculation s on th e effect s o f specifi c emission s substitutio nstrategie s o nai r qualit y i nspecifi c ai r pollutio nepisodes . A nexampl e o f thi s i s th e stud y o f a numbe r o f methano l fue l substitutio nscenario s onanai r pollutio nepisod e i nth e Californi a Sout hCoas t Ai r Basi nconducte db y Russel l e t al. , (1989) . Suc hanapproac hha s Che potentia l for givin g th e bes t availabl e estimate s o f ai r qualit y impact s fo r the specifi c case s whic har e examined , thoug hi c shoul db e recognize dtha t suc hcomple xmode l calculation s ar e no t withou t significan t uncertainties . However , chi s i s extremel y

expensiv e an

dit s result s ar e applicabl e onl y t o th e particula r ai r pollutio nepisod e andsubstitutio nscenario s whic hwer e examined . Becaus e o f this , thi s approac hi s probabl y no t practica l fo r th e evaluatio no f th e ful l rang e o f VO C substitutio noption s whic hnee dto be explored . Th e procedure s describe di nthi s pape r fo r assessin g ozon e impact s o f VO C emission s ar e als o base donairshe dmode l calculations , bu t o f a muc h
mor e idealize dtype . Rathe r tha nestimatin g impact s o f VO C emission s onP. 7

ozon e formatio ninspecifi c episode s (whic har e difficul t t o estimat e becaus e they

ar e highl y

dependen t onthe specifi c condition s o f th e episode s and inmos t case s requir e highl y comple xmulti-cel l gri d model s fo r accurat e representation) , the procedur e i s base do nestimatin g likel y impact s o f th e VOC s onozon e unde r generalize dset s o f conditions . Thi s i s a simple r modelin g proble m tha nestimatin g reactivitie s fo r a specifi c
se t o f conditions , sinc e the se t o f mode l scenario s employe dd o no t need t o accuratel y

represen t the detail s o f an y particula r ai r pollutio n episode ; al l tha t i s necessar y tha t th e se t o f scenario s represent s a realisti c rang e o f condition s whic hmigh t affec t reactivity . A n appropriat e se t o f idealize dmode l scenario s shoul db e sufficien t fo r thi s purpose . Severa l approache s coul db e employe dfor derivin g reactivit y scale s fo r generalize dset s o f conditions . Th e mos t obviou s woul d be t o determin e th e distributio no f al l airshe d condition s wher e ozon e formatio n i s a problem , an

d the ncalculat e the averag e reactivitie s fo r set s o f scenario s representin g chi s difference . However , chi s ha s severa l drawbacks . I t woul d requir e a comprehensiv e analysi s o f the distributio n
o f chemica l condition s i nairshed s whic hmigh t affec t VO C reactivities , whic hhas no t ye t bee ncarrie dout . Becaus e reactivitie s (includin g relativ e reactivities ) dependsignificantl y onthe relativ e availabilit y
o f NO xinth e system (Dodge , 1984 ; Carte r an dAtkinson , 1989) , th e reactivit y

scal e woul dbe particularl y sensitiv e t o th e distributio no f relativ e N0 V

level s whic hi s assumed . Thi s i s highl y uncertai n(e.g. , se e Bauges , 1986) . I

naddition , i t woul d no t b e appropriat e t o includ e i nthe averag e thos e condition s wher e ozon e formatio ni s N0 Xlimited, andwher e VO C contro l i s therefor e ineffectiv e a s a nozon e contro l strategy . Thi sP. 8

proble mca n t o som e exten t b e deal t wit h b yusin g aggregatio n method s whic h giv e greate r weight s t o reactivitie s in scenario s wher e VO C control s hav e th e greates t effec t o n ozone . A n alternativ e approac h i s t o conside r N0 Xavailabilit yseparatel y fro mal l othe r airshe d characteristic s whic h affec c reactivity
. Thi s ca n b e don e b

yderivin g separat e reactivit yscales , wher e eac h represent s a specifie d an d consisten t conditio n o f N0 Xavailability , bu t wher e eac h scal e represenc s aggregates , o r averages , o f othe r airshe d conditions
. Fo r example , one se c o f N0 Xcondicion s whic n coul d b e use d fo r derivin g a reactivit yscai e woul d b e thos e wher e VO C emission s nav e Ch e greates t effect s o n ozon e formation ; i.e. , th e N0 ; / level s wher e VOC s hav e thei r maximu mreactivities
. Thi s migh t b e a n appropriat e Dasi s fo r derivin g a reactivit yscal e fo r concro l strateg ypurposes , sinc e b ydefinitio n i t represent s condition s wher e VO C contro l i s tn e mos c effectiv e ozon e
concro l strateg y(Wei r e t al. , 1988) . A n alternativ e se t o f N0 X condition s whic h migh t b e appropriac e fo r derivin g a reactivit yscal e ar e thos e whic h resul c i n formacio n o f maximu m ozon e concentrations
. A s show n previousl y(Carte r an d Atkinson , 1989) , maximu mozon e concentration s alway s occu r a t N O level s whic h ar e lowe r tha n chos e wher e VOC s hav e chei r hignes t incrementa l reactivities
. Fo r example,.fo r a n idealize d one-da yscenari o wit h condition s representin g th e Lo s Angele s basin , maximu mVO C reactivitie s occu r a t a R0G/N0 Xrati o o f approximatel y6 , whil e maximu mozon e concentration s occu r a t a R0G/N0 xrati o o f approximatel y8 . I t ca n b e argue d tha t maximumreactivit yan d maximu mozon e condition s represen t respectivel yth e hig h an d lo wlimit s fo r condition s o f N0 X availabilit ywhic h ar e appropriat e fo r definin g a VO C reactivit yscale .P. 9

I f N0 Xlevel s ar e significantl yhighe r thanthos e o f maximu m reactivit y conditions , the n ozon e inhibitio n b yth e hig h N0 Xlevel s woul d preven t significan t concentration s o f ozon e fro mbein g forme d i n singl e da y episodes
. I f N0 Xlevel s ar e lowe r tha n thos e favorabl e fo r formatio n o f maximu mozon e concentrations , the n ozon e formatio n i s N O -limited , and unde r thos e condition s i t ha s bee n shown tha t change s i n VO C emission s hav e onl ysmal l effect s o n ozon e (Carte r and Atkinson , 1989) , an d thu s VO C contro l woul d b e a n ineffectiv e strateg yfo r controllin g ozon e formation
. I n th e section s below , th e derivatio n o f th e severa l differen t aggregate d reactivit yscale s ar e described , an d thei r prediction s o f reactivitie s ar e summarize d and compared . Thes e scale s ar e base d o n compute r mode l calculation s o f incrementa l reactivities , i n a variet yo f idealize d singl e da yozon e pollutio n scenarios , o f ch e ove r 14 0 organi c compound s represente d i n a recently-develope d detaile d reactio n mechanis m (Carter , 1990) . Th e scenario s employe a wer e base a o n previously-develope d EKMAmodel s o f o 2 city-aay s i n 1 2 urba n area s throughou t th e Unite d State s (Ger ye t al. , 1987 ; Whitten , 1988 ) an a represen t a wia e variet yo f condition s whic h migh t affec t VO C reactivities
.P.1 0

METHOD S

Quantificatio n o f Ozon e Reactivitie s I n thi s work , th e reactivit yo f a VO C wit h respec t t o ozon e formatio n i s measure d b

yit s "incrementa l reactivity"
. Thi s i s define d a s th e chang e i n ozon e cause d b yth e additio n o f th e VO C c o a particula r pollute d airshe d o f interes t (referre d t o a s th e "pollutio n scenario") , divided , b y th e amoun t o f VO C added .

Ozon e Forme d i n Ozon e Forme d Pollutio n Scenari o i n a n Idealize d wit h VO C Adde d t o - Pollutio n Scenari o Incrementa l Emission s (Tes t Case ) (Bas e Case ) Reactivit y= (I ) o f a VO C Amoun t o f VO C Adde d t o Emission s i n Tes t Cas e

T o avoi d dependenc e o f th e incrementa l reactivit yo n th e amoun t o f VO C added , th e incremenca l reactivit yi s define d a s Ch e limi t a s th e amoun t o f VO C adde a approacne s zero . Thi s als o permit s incrementa l reactivitie s o f mixture s VOC s t o b e calculace d b ylinea r summation s o f thos e o f thei r components . I f th e atmospheri c chemica l reactio n mechanis mfo r a VO C i s know n o r ca n b e estimated , it s incrementa l reactivit yfo r th e condition s
o f a specifi c pollutio n scenari o ca n b e estimate d b ycarryin g ou t mode l calculation s o f amount s o f additiona l ozon e formatio n cause d b yaddin g th e VO C t o th e emissions
. Equatio n (I ) i s base d o n quantifyin g reactivit yb yth e effec t o f th e VO C o n th e tota l amount , o r yield , o f ozon e whic h i s ultimatel yforme d fro mth e VOC . Quantifyin g ozon e b yozon e yield , a s oppose d t o ozon e concentratio n o r (a s discusse d below ) ozon e dos e ha s th e advantag e tha tP.1 1

incrementa l reactivitie s s o derive dar e unitles s quantities , reflectin g jus t molecule s o f ozon e forme dpe r molecul e o f VO C emitted . I f chemica l effect s ar e neglected , the y ar e independen t o f th e amoun t o f dilutio n occurrin g o r the lengt ho f tim e inthe scenario . Inaeed , i f difference s ineffect s o f reactivitie s onR0G/N0 Xratio s ar e take nint o account , incrementa l reactivitie s hav e bee nshow nt o be remarkabl y

insensitiv e to dilution , despit e significan t difference s inmaximu m ozon e concentration s whic har e forme d(Carte r an a Atkinson , 1989) . Fo r thi s reason: , reactivit y quantifie daccordin g t o Equatio n(I ) i s considere dco hav e Che bes t correspondenc e t o th e fundamenta l cnemica l processe s whic hoccu r onthe molecula r level . However , i

ncost-benefi t analyse s o f effects o f ozon e exposur e o n population s o r the environment , i t i s ofte nthe ozon e concentration s integrate dove r tim e whic hi s th e quantit y o f interest . Thi s i s referre d t o a s th e "ozon e dose " inthi s work .

Ozon e Dos e = / [0^]d t

T o determin e ho

w reactivitie s base donozon e dos e differe dfro m thos e base donozon e yield , fo r comparativ e purpose s "ozon e dos e reactivities "
wer e calculate dfo r representativ e VOCs . Thes e ar e define da s follows .

Ozon e Dos e ina Ozon e Dos e Pollutio nScenari o i na nIdealize d wit hVO C Adde dt o - Pollutio nScenari o Ozon e Dos e Emission s (Tes t Case ) (Bas e Case ) Reactivit y

= HI ) o f a VO C Amoun t o f VO C Adde dt o Emission s inTes t Cas eP.1 2

Again , th e reactivit y i s define da s the limi t o f lo w adde dVOC i

nthe tes t
case . Not e tha t reactivitie s define dinthi s manne r canno t be expresse d
a s unitles s quantities , an dtne y ar e directl y

dependen t o

ntne amoun t o f tim e inth e scenario . Fo r thi s reason , ozon e dos e reactivitie s ar e thu s
no t considere dt o D e particularl y meaningfu l i

nanabsolut e sense . However , ratio s o f ozon e dos e reactivitie s ca nprovid e a potentiall y usefu l basi s fo r derivin g relativ e reactivit y scales . Inth e subsequen t aiscussion , th e ter m "reactivity " withou t qualifier , o r "ozon e yiel a reactivity " wil l refe r c o reactivitie s define d usin g Equatio n(I) . I f ozon e aos e reactivity , i.e. . reactivit y calculate d usin g Equatio n(II) , i s being aiscussed , i t i s reference dexplicitl y a s such .

Chemica l Mechanis m

Use dfo

r Representativ e VOC s Th e chemica l mechanis m use dt o represen t th e reaction s o f the bas e
cas e RO GandNO . emissions , an dt o calculat e th e incrementa l reactivitie s A o f th e representativ e VOCs , wa s develope db y the autno r an

di s documente d indetai l elsewher e (Carte r 1990) . Thi s mechanis m contain s rat e constan t
an dproauc t yiel dassignment s fo r ove r 14 0 separat e "detaile dmode l species" , makin g i t the mos t detaile do f al l curren t state-of-the-ar t mechanism s i nterra s o f the numbe r o f organi c specie s whic hcanbe separatel y

represented . Becaus e o f the numbe r o f differen t VO C specie s it
ca nrepresent , i t i s particularl y suitabl e fo r us e i nreactivit y
assessmen t calculations . Thi s mechanis m

wa s teste dagains t ove r 50 0 environmenta l chambe r experiment s (Carte r e t al. , 1986 ; Lurman ne t al. , 1987 ; Carter , 1988 ; Carte r andLurmann , 1990a ) andinmos t case s coul dsimulat e experimentall y


### 1 0P.1 3

observe dozon e yield s t o withi n+30% . Thi s i s a s gooda s presentl y canb e expecte dwit hcurren t mechanisms , give nuncertaintie s incharacterization s
o f chambe r effects , combine dwit huncertaintie s inth e mechanism s themselve s (Carte r e t ai. , 1986 ; Ger y e t al. , 1988 ; Carte r an d Lurmann , 1990a , 1990b) . However , i t shoul db e recognize dtha t fo r man y VOC s the atmospheri c reactio nmechanis m i s highl y

uncertain , an

dth e availabl e environmenta l chamDe r dat a ar e sufficien t fo r testin g mechanism s for onl y
a relativel y

smal l subse t o f the VOC s whos e reactivitie s ar e calculated . Fo r mos t o f th e individua l VOCs , the onl y aspec t o f the mechanis m fo r whic hther e ar e dat a ar e the rat e constant s fo r thei r initia l reaction s i n th e atmosphere ; the mechanism s use dfor the reaction s o f the radical s subsequentl y

formed , wnic nar e responsibl e fo r ozon e formation , ar e estimate s base donanalogie s wit hthe fe w compound s whos e mechanism s ar e know ninmor e detail . (Relativ e level s o f uncertaint y inth e mechanism s
o f individua l VOC s ar e summarize d late r inthi s paper) . Nevertheless , the mechanis m

incorporate s ou r bes t presen t estimate s fo r th e reactio n mechanism s o f the wid e variet y o f VOC s whic har e emitte dint o th e atmosphere .

Pollutio nScenario s Use dfo r Reactivit y Estimate s Representativ e Pollutio nEpisodes . I nchoosin g a se t o f pollutio n scenario s t o us e for the estimatio no f VO C reactivitie s fo r a naggregate d
se t o f conditions , the objectiv e i s no t tha t th e scenario s necessaril y represen t i ndetai l an y particula r ai r pollutio nepisodes , bu t tha t the y b e sufficientl y

varie dtha t the

y represen t th e distributio no f chemica l condition s i nth e atmospher e tha t migh t affec t reactivity . Sinc e a larg e numbe r o f simulation s require di na comprehensiv e reactivit y study ,



### 1 1P.1 4

scenario s mus t no t b e s o comple xtha t simulatin g the m take s a larg e amoun t
o f compute r tim

e o r tha t they

requir e us e o f highl y condense d photochemica l mechanism s whic har e inappropriat e fo r reactivit y assessment s o f th e wid e variet y o f emitte dVOCs . However , the scenario s als o nee dt o be sufficientl y realisti c tha t they th e reactivitie s predicte dfo r the

m woul dno t be outsid e the rang e expecte dfor condition s
o f rea l airsheds . Th e developmen t o f a comprehensiv e se t o f idealize dpollutio n scenario s representin g th e tru e distributio no f ozon e pollutio ncondition s require s ananalysi s o f th e rang e o f condition s i nairshed s wher e ozon e formatio ni s a problem . Suc ha nanalysi s i s beyondth e scop e o f thi s study . Fortunately , a nextensiv e se t o f idealize dpollutio nscenario s ha s already bee ndevelope dfo r the purpos e o f city-specifi c EKM A analyse s (e.g. , se e Gipso ne t al. , 1981 ; EPA , 1984 ) o f ozon e formatio ni nvariou s
area s o f th e Unite dStates . Th e EKM A approac hinvolve s us e o f single-cel l boxmodel s o f on e da y urba nozon e pollutio nepisode s fo r the purpos e o f estimatin g the amoun t o f RO Greauctio nneede dc o reduc e ozon e C o achiev e th e nationa l ai r qualit y standar d(Dodge , 1977) . Althoug hEKM A model s us e onl y a singl e cel l formulation , an dthu s canno t represen t realisti c pollutio nepisode s ingrea t detail , the y canrepresen t dynami c injectio n
o f pollutants , time-varyin g change s o f inversio nheight s wit hentrainmen t
o f pollutant s fro

m alof t a s the inversio nheigh t increase s throughou t the day , andtime-varyin g rate s o f photolysi s reaction s andtemperatures . Thus , thes e model s ca nrepresen t a wia e rang e o f chemica l condition s whic h
ma y affec t prediction s o f effect s o f RO Gcontro l onozon e formation . Thes e chemica l condition s ar e th e sam e a s thos e affectin g prediction s o f VO C reactivity . Therefore , a t leas t exten t they ar e suitabl e fo r thei r



### 1 2P.1 5

intende dpurpose , th e existin g EKM

A scenario s shoul dals o b e suitabl e fo r
us e inreactivit y

assessmen t studies . Th e se t o f EKM

A scenario s (or EKM

A city-days ) use da s the startin g poin t i nthi s stud

y wer e thos e whic hhadbee nuse db y Gery e t al . (1987 ) i nthei r study

o f effect s o f changin g U V radiatio n(du e t o stratospheri c
ozon e depletion ) onozon e formatio ninvariou s urba nareas , an dthos e use d b y Whitte n(1988 ) to stud y the effect s o f change s i nozon e du e t o change s invehicl e fue l composition . Thes e intur nwer e take nfro m EKM A analyse s
use da s part s o f Stat e Implementatio nPlan s fo r reducin g ozon e invariou s
area s throughou t th e Unite dStates . Th e scenario s represente d6 2 episode s (city-days ) in1 2 differen t urba nareas . [Five o f ch e city-day s fro

m Whitte n(1988 ) represente depisode s whic hwer e als o o nth e se t fro

m Gery
e t al . (1987) , thougnth e inpu t condition s ar e sufficientl y differen t tha t they ar e treate da s separat e scenario s fo r th e purpos e o f thi s study. ] Th e majo r characteristic s o f thes e city-day s ar e liste dinTabl e 1 , whic h show s tha t a wid e variet y o f condition s ar e represented . Fo r example , the maximum calcuiate a ozon e range dfro m 7 6 pp b(wel l belo

w ch e Federa l ozon e standard ) u pc o almos c 0.3 7 ppm ; ch e maximu m inversio nheigh t range dfro m 40 0 t o 330 0 meters ; an dthe initia l plu s emitte dRO Gpollutan t inpu t range dfro

m les s than2 t o mor e than5 0 raillimoles mete r . N o clai m

i s mad e a s t o the accurac y o f thes e mode l scenario s i n simulatin g th e episode s they ar e designe dt o represent , thoug hclearl y the y wer e develope dwit ha nattemp t t o mak e thei r inpu t dat a and prediction s a s consisten t a s possibl e wit hth e availabl e (thoughgenerall y limited ) data . However , eve ni f they ar e no t accurat e inrepresentin g thei r particula r episodes , the y represen t th e modelers ' bes t effort s t o represent , a s accuratel y a s possibl e give nth e availabl e dat a an dthe



### 1 3P.1 6

limitation s o f th e formulatio no f the EKM A model , th e wid e rang e o f condition s occurrin g inurba narea s throughou t th e Unite dStates . Thi s variability , mor e thanth e accurac y o f an y particula r scenari o i n representin g a specifi c episode , make s the m usefu l for the objective s o f thi s study . Th e inpu t dat a fo r thes e scenario s wer e provide dt o th e autho r b y Ger y (1989 ) andWhitte n(1989 ) i nth e for

m o f inpu t file s t o the OZIP M (Gipson , 1984 ; Hog o an dGery , 1988 ) compute r program . Sinc e the availabl e version s o f th e OZIP M progra m ar e no t compatibl e wit hth e detaile d mechanis m

use dinthi s study , thes e input s wer e converte dfo r us e i nth e softwar e employe di nthi s study . Thi s involve dsome approximation s t o th e representation s use db y the OZIP M

program . Fo r example , i nthe simulation s reporte dher e the photolysi s rate s wer e calculate dusin g th e groun dleve l sola r actini c fluxe s give nb y Peterso n(1976 ) for hi s "bes t estimate " surfac e albedos , whic har e somewha t differen t fro m thos e use db

y th e OZIP M

program . T o partiall y correc t for this , ai l photolysi s rate s
wer e adjuste dupward s b y a facto r o f 1.09 3 t o yiel dthe same N0 2 photolysi s rat e a s calculate db y 0ZIPM 4 for direc t overhea dsun . Th e effect s o f thes e difference s o nth e mode l prediction s shoul db e minor . Perhap s mor e significantly , th e city-specifi c EKM A scenario s use din thi s study

wer e develope dusin g variou s version s o f th e Carbo nBon dgas phas e chemica l mechanis m (se e Ger y

e t al. , 198 8 an

dreference s therein) , whic hi s differen t i nsome respect s fro m the mechanis m

employe di

nthi s study . Althoug hthe lates t Carbo nBondmechanis m (Ger y e t al. , 1988) , lik e th e mechanis m

use dher e (Carter , 1990) , ca nbe considere dt o represen t th e curren t state-of-th e science , th e Carbo nBondmechanis m
canno t b e use dfo r developin g VO C reactivit y scale s involvin g larg e



### 1 4P.1 7

number s o f compound s becaus e i t i s a condense d mechanis m whic hdoe s no t provid e fo r representatio no f difference s betwee nmany individua l VOC s o f th e sam e genera l type . However , despit e th e difference s i nthe chemica l mechanism s andth e othe r modification s o f th e inpu t file s require d t o us e differen t softwar e system s t o simulat e the scenarios , th e simulation s o f maximum ozon e i nth e scenario s usin g the mechanis m an d softwar e employe d inthi s study

wer e foun

dno t t o be significantl y differen t (agreeing t o withi n+ 10 % o r better ) t o thos e calculate dusin g the Carbo nBon dI V mechanis m

(Gery e t al. , 1988 ) an

dth e OZIP P softwar e an dinpu t files . The y als o wer e no t significantl y differen t fro

m thos e reporte db

y Ger y e t al . (1988 ) usin g a nearlie r versio no f Carbo nBond . Inadditio nt o thes e city-specifi c EKM A scenarios , fo r compariso n purpose s reactivitie s wer e als o calculate dfo r the thre e idealize dEKMA typ e scenario s use d i nou r previou s reactivit y assessmen t studie s (Carte r
an dAtkinson , 1989) . Thes e wer e base donstandar dcity-specifi c EKM A input s fo r lo

w (EKMA-1) , mediu

m (EKMA-2 ) an

dhigh(EKMA-3 ) dilutio n region s designe db

y Gipso nan

d Frea s (1983 ) for us e i nRegulator y

Impac t Analyses . A s inou r previou s reactivit y studie s (Carte r an d Atkinson , 1989) , th e RO Ginpu t was hel dconstan t a t 1 2 millimole s mete r , an dthe N0 Xinpu t wa s varie d t o determin e the dependencie s o f reactivitie s o nthe ROG/NO xratio . - Th e majo r condition s o f thes e scenario s ar e als o summarize d o nTabl e 1 . Thes e scenario s wer e no t use d inderivin g the aggregate d reactivit y scales , bu t selecte d result s o f reactivit y calculation s using the m ar e include dher e fo r compariso nwit hresult s o f
ou r previou s studies .



### 1 5P.1 8

Representatio n o f Bas e Cas e RO G Compositions
. Th e compositio n
assume d fo r th e bas e cas e RO G emission s ha s bee n show n t o affec t prediction s o f reactivit y(Carte r and Atkinson , 1989 ; Wei r e t al. , 1988) ,
an d thu s i t i s importan t tha t thi s b e represente e a s accuratel ya s possible
. However , fo r mos t urDa n area s th e compositio n o f th e ROG emission s ar e highl yuncertain , and n o attemp t wa s mad e t o represen t th e city-specifi c RO G composition s i n th e developmen t o f th e EKM Ascenario s discusse d above . Instead , lik e Ger ye t al . (1987 ) an d Whitte n (1988) , a standar d defaul t representatio n o f th e RO G composition , whic h ha d bee n develope d base d o n ai r qualit ydat a i n a wid e variet yo f area s (e.g. , EPA , 1984 ; Killu s an d Whitten , 1984 ; Lurman n e t al. , 1987 ; Jeffrie s e t al. , 1989 ) wa s employed . Th e mos t recen t and probabl ymos t comprehensiv e analysi s o f detaile d VO C speciatio n dat a wa s carrie d ou t b yJeffrie s e t al . (1989) , wh o analyze d an d summarize d result s o f 86 0 groun d leve l and 16 0 alof t measurement s mad e i n variou s urba n area s throughou t th e Unite d States . (O f these , respectivel y77 3 and 5 3 sample s wer e considere d t o b e usabl e fo r analysis. ) Base d o n thes e data , the ydevelope d a n "all-cit y average " RO G compositio n profil e t o represen t typica l groun d leve l RO G emissions , an d a separat e "aloft " RO G profil e t o represen t composition s o f

suc h specie s aloft . Thes e composition s ar e considere d t o b e appropriat e fo r us e airshe d modelin g o f area s wher e reliabl e RO G speciatio n dat a ar e

no t available , an d wer e thu s use d i n al l scenario s employe d i n thi s study . Th e all-cit yaverag e an d alof t RO G composition s reporte d b yJeffrie s
e t al . (1989 ) wher e give n i n term s o f th e lumpe d specie s use d i n th e Carbo n Bon d I

V (Ger ye t al , 1988 ) and th e Lurman n e t al . (1987 ) condense d mechanisms
. Thes e ar e somewha t differen t tha n thos e use d i n th e mechanis m



### 1 6P.1 9

employe dinthi s study . Th e mechanis m employe dinthi s stud y use s variabl e lumpe dspecie s whos e mechanisti c parameter s ar e adjuste dbase do n th e compoun do r mixtur e they represent-(Carter , 1990) . Thi s require s knowledg e o f th e detaile dcomposition s o f th e mixtur e bein g represented . Fo r us e wit hthi s mechanism , th e detaile dcomposition s associate dwit h all-cit y

averag e andthe alof t mixture s derive db y Jeffrie s e t al . (1989 )
wer e obtaine dfro

m Jeffrie s (1988) . Th e detaile dcomposition s o f thes e tw o surrogate s ar e liste delsewher e (Carte r an dLurmann , 1990b) . I t shoul dbe note dtha t th e groundleve l measurement s analyze db y Jeffrie s e t al . (1989 ) di dno t includ e aldehyd e measurements . I nderivin g th e all-cit y

averag e mixture , Jeffrie s e t al . (1989 ) assume d51 aldehyd e compositio nassigne dt o the "allcit y

average " mixtur e i s base donpreviou s EPA-recommende d EKM A default s (e.g , EPA , 1984) , whic nwer e derive dbase d
o nhighl y

scattere dan

duncertai ndat a (see , for example , Lurman ne t al. , 1987) . Thi s i s a nuncertaint y whic hmay

affec t result s o f reactivit y calculations . Th e effec t o f thi s uncertainty , an donth e variabilit y bas e
cas e ROGcomposition s i ngeneral , i s bein g invescigaced , bu t i s beyon dth e scop e o f th e presen t paper .

Derivatio no f Aggregate d Bas e Cas e Reactivit y Scale s On e approac hfo r developin g a generalize dreactivit y scal e i s to aggregat e reactivitie s calculate dfo r a representativ e distributio no f ai r pollutio nepisodes . I f i t i s assume dtha t the pollutio nscenario s listed inTabl e 1 approximate s th e distributio no f suc hairsheds , the nthe y ca n b e use dt o develo psuc hanaggregate dscale . Althoug hth e exten t t o whic h thes e scenario s approximat e th e tru e distributio no f airshe dcondition s i s unknown , i t i s instructiv e t o se e ho w a naggregate dreactivit y scal e



### 1 7develope d usin g the mcompar e wit h reactivit yscale s develope d usin g othe r

methods . Therefore , a s par t o f thi s study , example s o f aggregate d reactivit y scale s wer e develope d usin g th e city-day s liste d i n Tabl e 1 , withou t an y
o f thei r inpu t condition s bein g modified
. Sinc e th e scenario s ar e essentiall yth e sam e a s use d b yGer ye t al . (1987 ) and Whitte n (1988 ) t o represen t bas e cas e condition s i n thei r respectiv e studies , the yar e referre d t o a s th e "bas e case " scenarios , and th e scale s derive d fro mthe m
a s th e "aggregate d bas e case " scales . (Thi s i s t o distinguis h the mfro m th e scenario s wher e th e N0 Xinput s wer e modifie d t o represen t "maximum reactivity " o r "maximumozone " conditions , a s discusse d below. ) T o avoi d givin g undu e weigh t t o thos e urba n area s fo r whic h Ger ye t al. , (1987 ) hav e man yepisodes , wit h on e exceptio n n o mor e tha n tw o episode s wer e use d fro m eac h urba n area . Atota l o f 2 1 episode s wer e use d t o deriv e th e aggregate d bas e cas e reactivit yscales ; th e specifi c episode s use d ar e indicate d i n footnote s t o Tabl e 1 . Fo r urba n area s wic h mor e Cha n cw o episode s lisce d o n Tabl e 1 , th e episode s chose n wer e thos e wit h th e smalles t and th e larges t chang e o f
ozon e wit h respec t t o changin g N0 Xemissions
. Th e on e exceptio n i s Tulsa , wher e th e W-TL 8 episod e use d b yWhitten , (1988 ) ha d a significantl ylowe r ROG/N O rati o tha n th e representatio n o f th e sam e episod e (G-TL8 ) use d b y Ger ye t al. , (1987) . Becam e o f thi s difference , th e W-TL 8 wa s treate d i n effec t a s i f i t represente d a differen t urba n area , an d thu s thre e "Tulsa " episode s wer e used . O n th e othe r hand , onl yon e "Ne wYork " episod e wa s used , becaus e th e tw o wer e ver ysimilar
.



### 18P.2 1

Quantificatio no f Reactivit y fo r th e Aggregate dBas e Cas e Scales . A s discusse dabove , reactivit y canbe define deithe r interm s o f effect s o f the VOC s o namount s o f ozon e formed , (Equatio nI ) o r onozon e dose s (Equatio nII) . Fo r the Das e cas e scenarios , separat e set s o f reactivit y scale s wer e derive dbase doneac ho f thes e tw o method s fo r quantifyin g
ozone . Th e same set s o f calculation s an daggregatio nmethod s wer e employe di neithe r case . Aggregatio nMethods . Ther e ar e severa l way s tha t th e reactivitie s fo r th e 2 1 bas e cas e episode s canbe aggregate dt o giv e a singl e reactivit y

scale . Sinc e th

e reactivitie s o f a give nVO C varie s widel y i n magnitud e fro

m scenari o t o scenario , i t i s considere dt o b e mor e appropriat e t o aggregat e o nthe basi s o f relativ e reactivities , rathe r tha nth e widel y

varyin g absolut e reactivities . Th e reactivit y o f the bas e
cas e ROGmixtur e i s chose na s the standar dagains t whic hth e reactivitie s
o f al l othe r VOC s ar e compare dina give nscenario . Give nthis , ther e ar e stil l a t leas t tw o way s thes e relativ e reactivitie s canb e aggregated . On e wa y i s simpl y

t o average , for each VOC , th e ratio s o f reactivitie s fo r eac ho f the episodes . Thi s i s referre dt o a s th e "averag e ratio " method . Thi s ha s th e advantag e o f simplicity , bu t th e disadvantag e tha t the scenario s wher e VO C reactivitie s
ar e ver y

lo w (i.e. , wher e VO C contro l i s a nineffectiv e ozon e reductio n strategy ) ar e give nequa l weigh t a s episode s wher e VOC s hav e high reactivities , an d thu s wher e VO C contro l i s muc hmor e effective . A n alternativ e aggregatio nmetho di s t o plot , fo r eac hVOC , th e reactivitie s
o f th e VO C agains t th e reactivitie s o f th e bas e cas e ROGmixture , an dt o
us e th e slop e o f th e leas t square s line , wit hintercep t force dthrough
zero , a s th e rati o o f th e reactivit y

o f tha t VO C relativ e t o the bas e cas e



### 1 9P.2 2

RO Gmixture . (Example s o f suc hplot s ar e give ninth e Result s section , below) . Thi s i s referre dt o a s th e "lin e fit " method . Thi s aggregatio n metho dha s th e advantag e o f givin g greate r weigh t t o episode s wher e VOC reactivitie s ar e higher , whil e stil l takin g int o account , a t leas t t o som e extent , th e reactivitie s calculate dfo r al l the episodes . Bot hmethod s
ar e use dinthi s study .

Derivatio no f th e Maximu m Reactivit y

an dth e Maximu

m Ozon e Reactivit y Scale s Th e aggregate dbas e cas e reactivit y scale s necessaril y reflec t th

e distributio no f condition s i nth e specifi c se t o f scenario s use dt o deriv e chem , Choug hrelativ e contribution s o f differen t type s o f scenario s t o the resultin g scal e ca nbe varie db y usin g differin g aggregatio napproaches . A nalternativ e approac hi s t o deriv e reactivit y scale s whic hrepresen t specifi c type s o f scenari o conditions . Since , a s discusse dabove , th e
mos t importan t scenari o conditio naffectin g reactivit y i s the availabilit y
o f NO,. , thi s wa s use da s th e basi s fo r definin g scenari o condition s fo r derivin g separat e reactivit y scales . Fo r thi s purpose , "N0 Xavailability " i s measure db

y th e effect s o f N0 Xonth e reactivit y characteristic s i

nthe scenarios , wit hon e scal e representin g N0 Xcondition s yieldin g maximu m VO C reactivities , andanothe r representin g N0 Xcondition s yieldin g maximu m amount s o f ozon e formed . Not e tha t ingenera l R0G/N0 xratio s yieldin g maximum VO C reactivitie s
andmaximum

02on e formatio nca nvary significantl y

fro m scenari o t o scenario , dependin g o nothe r condition s (Carte r andAtkinson , 1989 ; se e als o result s below. ) Fo r example , sinc e th e rat e a t whic hN0 Xi s consume d woul dincreas e wit hligh t intensity , a ROG/NO xrati o whic hi s inth e N0 X limite d regim e a t a hig hsunligh t intensit y may no t b e intha t regim e i f

2 0P.2 3

th e sunligh t intensit y wer e reduced . Therefore , the ROG/N O rati o itsel f i s no t considere dadequat e fo r quantifyin g N0 Xavailabilit y whe na variet y
o f scenario s ar e bein g considered . Fo r th e purpos e o f derivin g thes e reactivit y scale s fo r eac ho f the 6 2 city-days-liste d inTabl e 1 , th e tota l N0 Xemission s inpu t wa s varie d t o determin e th e level s whic hyielde dthe highes t VOC reactivitie s an dthe level s wit hhighes t maximu m ozon e concentrations . .Th e relativ e NO emission s schedules , level s o f N0 Xalof t (i nth e fe w scenario s wher e thi s i s applicable) , the tota l ROGemission s input , an d al l othe r aspect s o f thes e scenario s wer e no t varied . Th e incrementa l reactivit y o f th e surrogat e representin g bas e cas e ROGemission s wa s use d a s th e criterio n t o determin e th e N0 Xlevel s correspondin g t o maximu m reactivity . (Incrementa l reactivitie s for toluene , formaldehyae , propen e andC O wer e als o calculate da s a functio no f ROG/NO xratio , an dth e ratio s yieldin g highes t reactivitie s fo r thes e compound s wer e similar , bu t no t alway s exactl y th e same , t o th e rati o yieldin g th e highes t base ' cas e RO G reactivity. ) Th e scenario s or city-day s wit hNO., , level s adjuste dt o yiel c th e hignes t caicuiate a reactivit y o f the bas e cas e RO Gemission s ar e referre dt o i

nth e subsequen t discussio na s che "maximu m reactivity " scenarios , whil e chos e wit hN0 Xlevel s yieldin g th e highes t calculate d maximum ozon e concentration s ar e referre d co a s the "maximu m ozone " scenarios . Th e N0 Xinput s derive d fo r eac hse t o f scenario s ar e give n wit hth e tabulation s i nthe Result s section . A s indicate dabove , the othe r aspect s o f th e scenario s wer e the sam e
a s use dinth e bas e cas e scenario s (i.e. , wer e a s indicate donTabl e 1. ) Thus , ineffect , the reactivit y scale s for maximu

m reactivit y

o r maximu

m
ozon e N0 Xcondition s represen t aggregat e average s ove r thes e othe r airshe d



### 2 1conditions . However , sinc e thes e condition s ingenera l hav e smalle r

effect s o noveral l reactivities , th e range s o f reactivitie s bein g aggregate dshoul di nprincipl e be less , andthu s the result s shoul dbe les s sensitiv e t o th e specifi c se t o f scenario s employed . Separat e Estimate s o f React!vir. y rT o furthe r ^ ^ ^
rang e o f variabilit y o f quantitie s whic har e bein g average dfo r the variou s scenarios , andt o examin e inmor e detai l ho w variou s environmenta l
andmechanisti c factor s affec t reactivit y unde r give ncondition s o f N0 X availability , th e tw o majo r component s o f VO C reactivit y wer e considere d separatel y

i nth e derivatio no f th e maximu m reactivit y

an dthe maximu

m
ozon e reactivit y

scales . As discusse dpreviousl y (Carte r an

dAtkinson , 1989) , incrementa l reactivitie s ca nbe though t o f a s bein g product s o f tw o factors , whic hwe hav e designate da s "kinetic " an d"mechanistic " reactivities . Th e kineti c reactivit y i s define dthe fractio no f the emitte dVO C whic hundergoe s chemica l reactio ninthe pollutio nscenari o bein g considerea ,

Kineti c Fractio nVO C Reacte d Reactivit y

= Reacte d= , VO C Emitte d

andth e mechanisti c reactivit y i s the amoun t o f ozon e forme drelativ e t o th e amoun t o f VO C whic hreact s i ntha t scenario .

Mechanisti c Ozon e Forme d Reactivit y

= (IV ) VO C Reacte d



### 2 2P.2 5

Th e produc t o f thes e tw o quantitie s the ngiv e th e overal l incrementa l reactivity .

Incrementa l Kineti c Mechanisti c Reactivit y

= Reactivit y XReactivit y (V ) Ozon e Forme dVO C Reacte dOzon e Forme d ( ) = ( ) X( ) VO C Emitte dVO C Emitte dVO C Reacte d

Thes e tw

o component s o f incrementa l reactivity , eac ho f whic har e affecte d b y differen t aspect s bot ho f th e VOC s reactio nmechanis m andth e conaition s o f th e airshe dscenario , ar e mor e straightforwar dt o estimat e tha noveral l incrementa l reactivity . Considerin g thes e tw o component s o f reactivit y

separatel y

ca nals o provid e a basi s fo r makin g reactivit y estimate s fo r VOC s whos e atmospheri c reaction s ar e no t represente dinthe chemica l mechanism s use di ncurren t airshe dmodels . Derivatio no f Kineti c Reactivities . Th e kineti c reactivit y o f a VO C i s aefine a a s th e fractio no f the emitte dVO C whic hundergoe s chemica l reactio ni

nth e ai r pollutio nepisode . It depena s o nho w rapidl y

th e VO C react s inth e atmospher e an do ncondition s o f the episode s suc ha s overal l ligh t intensit y

andradica l levels , bu t no t o nth e othe r aspect s o f thei r reactio nmechanism . Fo r mos t type s o f emitte dVOCs , reactio nwit h hydroxy l radical s i s th e onl y significan t proces s b y whic hthey

reac t in th e atmosphere . Thus , fo r thes e compounds , th e kineti c reactivit y depend s onl y o nth e rat e constan t for the reactio no f th e compoun dwit hO H radicals , an dth e overal l leve l o f O H radical s inthe pollutio n scenarios . I nsuc hcases , th e kineti c reactivity , whic hha s als o bee n calle dth e "O H reactivity" , canbe approximate db y th e followin g empirica l relatio n(Carte r andAtkinson , 1989) :


### 23P.2 6

Kineti c Fractio n. k0 H T • Reactivit y

= Reacte d= ( i . e t0 H ) (VI )

wher e kO H i s th e VOC s rat e constan t fo r reactio nwit hO H radicals , an d IntO H i s a scenario-dependen t paramete r whic hreflect s primaril y the overal l integrate dO H radica l level s o f the scenario . Th e O H radica l rat e constant s ar e know

nfo r a wid e variet y o f organi c compound s (Atkinson , 1986,1989) , an dmethod s exis t fo r estimatin g the m fo r mos t other s (Atkinson , 1987) . IntO H value s appropriat e fo r a give npollutio nscenari o canbe obtaine db

y calculate dratio s o f amount s reacte dt o amount s emitte dfo r specie s wit hvaryin g O H radica l rat e constants , an dderivin g th e valu e wher e thes e ar e fi t b y equatio n(VI) . Th e IntO H value s calculate dfo r th e individua l maximum

reactivit y

o r maximu

m ozon e scenario s ca nthe nbe use d t o deriv e value s whic har e appropriat e fo r estimatin g kineti c reactivitie s appropriat e fo r thes e tw o set s o f conditions . Equatio n(VI ) i s base do nassumin g tha t th e compoun dreact s significantl y

onl y wit hO H radical s an dthu s wil l underestimat e th e kineti c reactivitie s fo r compound s whic hreac t non-negligibl y b y othe r processes . Th e majo r example s o f thi s ar e aldehyde s an dketones , whic h
reac t non-negligibl y b y photolysis , an

dalkenes , whic hals o reac t non negligibl y

with " ozone . Inthe cas e o f compound s whic hreac t wit hOH radical s s o rapidl y tha t the

y woul dbe estimate dt o be completel y consume d
eve ni f th e othe r los s processe s ar e ignored , th e underestimatio no f kineti c reactivit y

cause db

y ignorin g thes e othe r processe s woul db e insignificant . Thi s woul dbe th e cas e fo r propen e an dth e highe r alkenes , whic hEquatio n(VI ) calculate s t o be a t leas t 95 } reacte dunde r maximu m reactivit y

conditions , an

da t leas t 99 9 reacte dunde r maximu m ozon e


### 2 4P.2 7

conditions . However , fo r ethene , the ketones , an d(i nsom e cases ) th e aldehydes , th e us e o f Equatio n(VI ) woul d underestimat e kineti c reactivities . Therefore , Equatio n(VI ) i s no t use dt o estimat e kineti c reactivitie s fo r thes e compounds ; instead , the fraction s reacte dwer e calculate d explicitl y fo r variou s maximu m reactivit y

an dmaximu

m ozon e scenarios . Th e value s obtaine dar e thencomDine d to obtai nestimate s o f kineti c reactivitie s fo r thes e compound s whic har e appropriat e fo r the tw o set s o f conditions . Calculatio no f Mechanisti c Reactivities . Mechanisti c reactivitie s
measur e th e amoun t o f ozon e forme dcause db y the reactio no f a give n
amoun t o f th e VOC , independentl y (t o a firs t approximatio na t least ) o f

' ho w rapidl y

th e compoundreacts . They ar e determine db

y th e natur e o f the VOC s reactio nmechanism , suc ha s number s o f conversion s o f NO t o N0 2 whic h
occu r durin g it s oxidatio nprocess , whethe r the reaction s enhanc e o r inhibi t radica l o r N0 Xlevels, an dthe reactivitie s o f th e product s the y form . They

ar e als o strongl y

affecte db

y th e condition s o f th e scenari o
suc ha s the V0C/N0 xrati o an d othe r aspect s whic haffec t th e overal l efficienc y

o f ozon e formatio n(Carte r an dAtkinson , 1989) . Dependin g o n th e condition s o f the scenari o an d the natur e o f the reactio nmechanisms , mechanisti c reactivitie s ca nrang e fro m negativ e value s (indicatin g th e VOC s reaction s actuall y reduc e overal l ozon e formation) , t o value s a s hig ha s ove r 1 0 mole s o f ozon e forme dpe r mol e carbo nreacte d (Carte r an d Atkinson , 1989) . T o obtai ninformatio nnecessar y t o deriv e comprehensiv e VO C reactivit y

scale s fo r maximu

m ozon e an

dfo r maximu

m reactivit y

conditions , mechanisti c reactivitie s wer e calculate dfo r al l the VO C specie s whic hca n b e separatel y

represente di

nth e detaile dphotochemica l mechanis m (Carter ,



### 25P.2 8



### 1990) . Th e mechanisti c reactivitie s o f a 

### vo c i n, a VU L m a give nscenari o canbe calculate db

y compute r mode l simulation s o f th e \inr>- • u i cne VOC s incrementa l activit y

(uS 

### i „ g Equatlo n

### „ a 

### „ dfractlo n

### ^^ ^ <kineci c 

### ^ ^ ^ th e scenario , anddividin g tn e 

### incrementa l reactmt y o y 

### ^ ^ ^ reacted . Fo r some VOCs , mechanisti c reactivitie s wer e no t calculate d Erectly , bu t instea d uer e derlve d fro nmechanlst 

### . o reactivr 

### . t 

### . e s 

### calculate dfo r specie s fo r simplifie da„ c idealize dreactionmechanisms . Th e method s fo r estimatin g reactivitie s base donidealize dmechanis m species , and the type s o f idealize dspecie s .„!„, „ specie s employed , ar e discusse d elsewher e (Wei r e t al , 1988 ; Carte r an dAtkinson , 19 

### 8 9 

### ) . Tes t calculacion s showe dtha t mechanisti c reaori,, ^ ecnanisti c reaccivicie s calculate dthi s wa y wer e no t significantl y

differen t fro

m thos e calculate ddirectly . Becaus e o f the larg e numbe r o f VO C specie s an dscenarios , complet e calculation s o f mechanisti c reactivitie s uer pnor _ . activitie s wer e no t carrie dou t fo r al l the case s for thos e urba narea s whic hhadmor e thantu n*„**- uju t e tnancw

o scenarios . Fo r thos e areas , mechanisti c reactivitie s wer e caimiarar t ?- 3 wer e calculate dror a t leas t tw o selecte d scenarios , on e o f whic hhadth e highes t an

don e o f „h lC 

### hhadthe lowes t bas e cas e ROGreactivity. Th e tabulatio no f the result s indicat e th e scenario s used . Thes e shoul dbe sufficien t t o represen t the variabilit y o f mechanisti c reactivitie s l n

### the scenario s fo r a narea . (T o tes t thi s mechanisti c reactivitie s fo r a smal l numbe r o f selecte drepresentativ e specie s wer e calculate dfo r al l the othe r maxim a reactivit y andmaximu

m o*on e scenarios. , Th e result s wer e thenuse dt o obtain , fo r eac hVOC represente dinthe detaile dmechanism , mechanisti c reactivitie s appropriat e fo r maximu m reactivit y

an dfo r maximu

m ozon e conditions .

26P.2 9



### RESULT S AND DISCUSSIO N

Calculate d VO C Reactivitie s fo r MaximumReactivit yan n MOV<

—Ozon e 

### Condition s ~"^~———— — Th e result s o f th e calculation s fo r th e maximu mreactivit yand th e maximu mozon e condition s ar e give n o n Table s 2 throug h 4 . Table s 2 lists , fo r eac h o f th e 6 2 city-day s and th e thre e idealize d EKM Ascenarios , th e R0G/N0 X

### rati o foun d t o giv e maximu mVO C reactivitie s and selecte d reactivit yresult s fo r th e city-day s a t thes e N0 X

### levels . Thes e includ e th e maximu mozon e concentration , th e reactivit yo f th e bas e cas e RO G surrogate , th e IntO H parameter , an d th e kineti c an d mechanisti c reactivitie s fo r selecte d representativ e species
. Tabl e 3 give s th e correspondin g result s fo r th e N0 X

### condition s givin g maximu m ozon e concentrations
. Table s 2 an d 3 als o giv e th e average s o f th e reactivit y result s fo r eac h o f th e 1 2 urba n area s represente d b yth e 6 2 city-days , an d th e overal l average s o f th e average s fo r al l th e urba n areas . Th e average d kineti c and mechanisti c reactivit yresult s fo r maximum reactivit yan d maximu m ozon e condition s ar e summarize d o n Tabl e 4 . Th e average s wer e obtaine d b yfirs t calculatin g th e averag e fo r eac h o f th e 1 2 urba n areas , an d the n averagin g th e average s fo r thes e areas , i n a manne r analogou s t o th e representativ e result s show n o n Table s 2 and 3 . Fo r compound s whic h reac t onl ywit h O H radicals , estimate d kineti c reactivitie s wer e derive d usin g Equatio n (VI) , usin g

IntOH = 8 2 ppt-mi n fo r maximum reactivit yconditions , an d IntO H = 12 8 ppt-mi n fo r maximum ozon e conditions
.

2 7P.3 0

Thes e wer e th e average s o f the averag e value s fo r th e 1 2 urba nareas , take nfro

m Table s 2 o r 3 . Th e mechanisti c reactivitie s fo r compound s whic hreac t wit hspecie s othe r thanO H radical s wer e eithe r average s o f th e value s calculate dexplicitly , o r assigne da valu e o f unit y base don assumptio no f essentiall y complet e reaction . Footnote s t o Tabl e 4 indicat e ho

w th e estimate dkineti c an dmechanisti c reactivitie s wer e derive dfo r eac ho f th e individua l VOCs . Th e estimate dkineti c andmechanisti c reactivitie s o nTabl e 4 wer e the ncombine dt o obtaine dth e aggregate dincrementa l reactivit y estimate s fo r maximu

m reactivit y

o r maximu

m ozon e conditions . Th e incrementa l reactivitie s ar e give ninunit s o f bot hmole s ozon e forme dpe r mol e carbo n VO C emitted , an

dgram s ozon e forme dpe r gra m VO C emitted . Not e tha t i n term s o f relativ e reactivities , the choic e o f unit s ca nmak e a differenc e whe nconsiderin g reactivitie s o f oxygenate dcompounds . Fo r example , unde r maximum reactivit y

conditions , methano l ha s about th e same reactivit y a s
mos t branche dC4-C 6 alkane s whe nreactivit y i s measure dona per-carbon emitte dbasis , whil e i t i s les s thanhal f a s reactiv e thanthos e compound s whe ni t i s measure do na per-mas s basis . Per-carbo nunit s ar e perhap s o f
mor e fundamenta l chemica l interest , an dfo r tha t reaso nar e th e unit s w e
us e fo r mechanisti c reactivit y results . However , per-mas s unit s ar e probabl y

mor e usefu l fo r contro l strategy purposes , sinc e VO C emission s
ar e generall y

measure dan

dregulate do

na mas s basis . Fo r tha t reason , reactivitie s measure do na per-mas s basi s ar e use dwhe nresult s ar e give n comparin g differen t reactivit y scales . Compariso no f Kineti c an dMechanisti c Reactivitie s fo r Maximu m Ozon e
andMaximu

m Reactivit y

Conditions . Th e representativ e dat a o nTable s 2
and3 indicat e tha t kineti c reactivitie s a t N0 Xlevel s yieldin g maximu m



### 2 8P.3 1

ozon e concentration s ar e highe r thanthos e fo r N0 Xlevel s yielding maximu m VO C reactivities . Thi s i s expected , sinc e th e reactio no f O H radical s wit hN0 2 i s a nimportan t radica l terminatin g process , andN0 2 level s ar e highe r unde r maximu m reactivit y

conditions . Onth e othe r hand , th e mechanisti c reactivitie s fo r maximu m ozon e condition s ar e lower , b y a t leas t a facto r o f two , tha nth e value s whic har e observe dunde r maximu m reactivit y

conditions . Sinc e (b y definition ) the incrementa l reactivitie s
ar e highe r unde r maximu m reactivit y

conditions , i t i s clearl y th e mechanisti c reactivitie s whic har e the mor e importan t ininfluencin g ho w overal l incrementa l reactivitie s vary wit hV0C/N0 V . Thi s i s consisten t wit hth e result s whic hhav e bee npresente dpreviousl y (Carte r an

d Atkinson , 1989) . I f th e relativ e difference s betwee nthe mechanisti c reactivitie s unde r th e tw

o set s o f condition s wer e th e same fo r al l type s o f VOCs , then th e difference s woul d hav e n o practica l significanc e interm s o f developin g VOC reactivit y scales . However , thi s i s no t th e case . Figur e 1 show s plot s o f mechanisti c reactivitie s o f the VOC s fo r maximu m ozon e condition s agains t thos e fo r maximu m reactivit y

conditions . I f th e ratio s
o f mechanisti c reactivitie s fo r maximu m ozon e an

dmaximu

m reactivit y condition s wer e simila r fo r al l compounds , th e point s woul dal l b e o n approximatel y

the same line , wit hthe slop e bein g th e rati o o f mechanisti c reactivitie s fo r th e tw o set s o f conditions . However , i t canbe see ntha t althoug hcompound s o f simila r type s ten d t o fal l onth e sam e line , th e line s ar e differen t fo r differen t classe s o f compounds . Fo r example , the rati o o f mechanisti c reactivitie s fo r maximu m ozon e relativ e t o maximu m reactivit y

condition s ar e significantl y lowe r fo r th e carbony l compound s
andth e aromatic s (especiall y naphthalen e an

dtetralin) , andsomewha t



### 29P.3 2

lowe r fo r th e alkenes , thanthe y ar e fo r th e alkanes . However , i t i s th

e overal l incrementa l reactivity , no t the mechanisti c reactivity , whic hi s o f direc t relevanc e fo r VO C reactivit y scales . Fo r th e mos t slowl y reactin g compounds , th e highe r radica l level s i nmaximum

ozon e condition s relativ e t o maximu m reactivit y

condition s in par t offset s th e opposin g effect s o f difference s i nmechanisti c reactivity . Fo r example , despit e the facto r o f 2 differenc e i n mechanisti c reactivity , the incrementa l reactivit y o f methan e inmaximu m
ozon e condition s i s onl y -30/ . lowe r thanit s reactivit y i nmaximu

m reactivit y

conditions . Onthe othe r hand , fo r rapidl y reactin g compound s ther e i s relativel y littl e differenc e betwee nkineti c reactivitie s (sinc e th e compound s ar e almos t completel y reacte dinan

y case) , an

dthu s fo r th e difference s i

nincrementa l reactivit y wil l b e determine dentirel y b y difference s inmechanisti c reactivities . Comparison s o f overal l reactivitie s fo r thes e tw o set s o f condition s
ar e show

no nFigur e 2 , whic hgive s plot s o f reactivitie s fo r maximu m ozon e condition s agains t reactivitie s fo r maximu m reactivit y

condition s fo r the individua l mode l species . Th e reactivitie s fo r CO , the alkanes , alcohols , ethers , glycol s an

dth e ketone s hav e bee nmultiplie db y five , teno r 10 0
s o thei r magnitude s woul dbe comparabl e t o thos e fo r the aromatics , alkenes , an d aldehydes . Figur e 2 i ngenera l ha s th e sam e feature s a s indicate dinFigur e 1 ; unde r maximu m ozon e condition s th e reactivitie s o f th e aromatics , oxygenates , an dalkenes , relativ e t o thos e fo r th e alkane s
andalcohols , ar e lowe r unde r maximu m ozon e condition s tha nthey ar e unde r maximum reactivit y

conditions . Thi s show s th e importanc e i nmechanisti c reactivitie s i ndeterminin g th e dependenc e o f overal l reactivitie s on relativ e N0 Xlevels . I naddition , the difference s betwee nth e relativ e



### 3 0P.3 3

incrementa l reactivitie s o f the alkane s andth e alkene s (a s show non Figur e 2 ) ar e greate r thanon e woul dexpec t fro m thei r difference s in relativ e mechanisti c reactivitie s a s show nonFigur e 1 . Thi s i s becaus e th e highe r radica l level s o f the maximu m ozon e condition s ten dt o decreas e th e difference s inth e reactivitie s fo r th e relativel y mor e slowl y reacting alkane s t o a greate r exten t thanthey d o for th e relativel y rapidl y reactin g alkenes . Thi s effec t onalkane/alken e reactivit y ratio s i s inth e sam e directio na s the effec t o f th e rati o o f thei r mechanisti c reactivity , andthu s enhance s the difference s i nthei r relativ e reactivitie s betwee nthe tw o scales . T o illustrat e the effec t o f changin g onl y th e overal l radica l levels , andthu s th e kineti c reactivities , o nthe reactivit y

scales , Figur e 3 show s plot s o f incrementa l reactivitie s calculate dusin g maximu m ozon e kineti c reactivities , agains t thos e usin g maximu m reactivit y

kineti c reactivities , wher e bot hus e maximu m reactivit y

mechanisti c reactivities . Consisten t wit hthe discussio nabove , th e larges t effec t o f overal l radica l level s i s o nthe reactivitie s o f the rapidl y reactin g compound s (e.g. , alkene s an daldehydes) , relativ e t o thos e whic hreac t
mor e slowly . However , the rang e o f difference s i nreactivit y

whe nonl y th e kineti c reactivitie s ar e varie di s muc hles s thanth e rang e o f difference s i noveral l reactivities , an di s als o les s (especiall y fo r th e aromatics ) tha nwhe nthe mechanisti c reactivitie s ar e varie d(compar e Figur e 3 wit hFigure s 2 an d1) . Dependencie s o f Reactivitie s onNon-Nn ir -Reiate d Airshe dConditions . A study o f th e dependenc e o f reactivit y onnon-NO x -relate d airshe d condition s i s complicate db y the fac t tha t mos t airshe dcondition s wil l affec t th e rat e tha t N0 Xi s consume ddurin g th e day , whic hinturn



### 3 1P.3 4

determine s th e leve l o f N0 Xwhic hdefine s th e boundar y betwee nNO x -limite d
andVO C reactivity-sensitiv e conditions . .Fo r example , increasin g the ligh t intensity , dilution , o r th e amoun t o f radical-initiatin g specie s i n th e bas e cas e RO

Gmixtur e al l increas e radica l level s inth e scenario , whic hincrease s N0 Xconsumptio nrate , an dthu s result s inNO„-limitin g condition s occurrin g a t highe r N0 Xlevels . Thu s th e mai nreaso nfo r difference s inreactivitie s calculate dfo r differen t scenario s a t th e same ROG/NO xrati o i s tha t th e give nrati o ca ncorrespon dt o differen t condition s o f relativ e N0 Xavailabilit y i nth e differen t scenarios . Holdin g th e ROG/NO xrati o fixe dtherefor e doe s no t assur e consisten t condition s o f N0 Xavailability . However , th e derivatio no f separat e reactivit y scale s fo r maximu

m reactivit y

o r fo r maximu

m ozon e condition s ha s th e advantag e tha t i t tend s t o facto r out , a t leas t t o som e extent , effect s onreactivitie s o f variabilitie s o f condition s N0 Xavailability . Thi s i s becaus e inthe derivatio no f thes e scale s the N0 Xinput s o f eac hscenari o ar e adjuste dt o yiel dconsisten t condition s o f N0 Xavailability . Therefore , i f ther e i s stil l variabilit y

inreactivitie s calculate damon g th e variou s scenario s wher e condition s o f relativ e N0 Xavailabilit y ar e hel dfixed , thi s woul d b e du e t o effect s o f other , non-NO x -relate dairshe dconditions . A s show nonTabl e 1 , ther e i s considerabl e variabilit y among.th e scenario s i nterm s o f amount s o f dilution , tota l VO C inputs , integrate d ligh t intensity , amount s o f pollutant s entraine dfro m aloft , andrelativ e amount s o f pollutant s presen t initiall y o r emitte ddurin g th e day . Table s 2 and3 show

tha t th e variabilit y inthes e condition s indee dcaus e variabilitie s i nparameter s whic haffec t reactivities . Thi s i s als o show n
o nFigur e 4 , whic hgive s distributio nplot s fo r value s o f thes e parameter s



### 32calculate dfo r selecte dcity-day s ineac ho f th e 1 2 urba nareas . (The

city-day s selecte dfo r th e maximu m reactivit y

an dfo r th e maximu

m ozon e condition s wer e thos e use dt o calculat e th e mechanisti c reactivitie s fo r th e mode l species . Al l th e city-day s ar e no t show no nth e distributio nt o avoi dweighin g undul y thos e urba narea s whic hhav e th e mos t city-days. ) Fo r comparison , Figur e 4 als o show s th e distribution s fo r th e city-day s wit hth e bas e cas e N0 Xconditions , whic huse dt o deriv e th e aggregate d bas e cas e an

dozon e yiel dandozon e dos e reactivit y scales . A s expected , adjustin g th e N0 Xlevel s t o yiel deithe r maximu m reactivit y

o r maximu

m ozon e condition s indeedresult s inmuc hnarrowe r distribution s o f reactivit y parameter s thani s th e cas e fo r th e unadjuste d (e.g. , bas e case ) scenarios . However , ther e i s stil l a non-negligibl e variabilit y

o f value s eve nafte r N0 Xi s adjusted . Thi s show s tha t reactivitie s ar e indee daffecte db y th e variabilit y

o f th e other , non-NO x related , airshe dconditions . However , the compariso no f th e bas e cas e distribution s wit hthos e fo r maximu m reactivit y

o r maximu

m ozon e N0 X condition s clearl y

indicat e th e over-ridin g importanc e o f variabilitie s in N0 Xlevel s inaffectin g reactivitie s invariou s urba nareas . Ingeneral , a t leas t fo r th e scenario s an durba narea s use d inthi s study , th e urban-area-average dreactivit y oarameter s ten

dt o hav e a standar ddeviatio no nth e orde r o f +25%, thoughinsome case s extreme value s fo r certai nindividua l scenario s ca ndiffe r b y a facto r o f 3 o r
more . Th e exten t o f variabilit y fo r maximu

m reactivit y

andmaximu

m ozon e condition s ten

dt o b e similar . Th e exception s t o thes e generalization s
ar e th e mechanisti c reactivitie s fo r th e CQ + alkane s unde r al l conditions , an dth e mechanisti c reactivitie s o f th e aromatic s (othe r tha ndi - o r tri alkylbenzenes ) unde r maximu m ozon e conditions , whic htendt o b e lo w in



### 33P.3 6

magnitud e andhav e highrelativ e variabilities . Inaddition , th e highe r molecula r weigh t alkene s ten dt o hav e highe r variabilitie s inmechanisti c reactivitie s (wit hstandar ddeviation s onth e orde r o f +30% ) unde r maximu m
ozon e conditions . Th e variabilit y

inth e IntOH parameter , whic hreflect s integrate dO H radica l level s an

dthu s fraction s o f VOC s whic hreact , i s comparabl e t o th e variabilitie s inthe mechanisti c reactivities . It s variabilit y yield s
a correspondin g variabilit y i nth e kineti c reactivitie s o f the slowl y reactin g compounds , sinc e fro m Equatio n(VI ) fraction s reacte dbecom e proportiona l t o IntOH whe nth e O H radica l rat e constan t become s sufficientl y

small . Th e variabilit y i nkineti c reactivitie s i s significantl y

les s fo r the mor e rapidl y reactin g compound s (includin g mos t
o f thos e whic hreac t wit hspecie s othe r tha nOH radicals) , sinc e th e fractio nreacte dapproac hth e uppe r limite dvalu e o f unity . Thus , fo r
mos t reactiv e compounds, , i t i s th e variabilit y o f mechanisti c reactivit y wit hairshe dcondition s whic hi s th e mor e importan t facto r whic hi s influencin g variability , an dthu s uncertainties , o f incrementa l reactivitie s fo r maximu m ozon e o r maximu

m reactivit y

conditions . Figur e 3 give s a nindicatio no f th e sensitivit y o f the reactivit y

scale s t o uncertaintie s inth e IntOH parameter . Th e reactivitie s show nther e sho

w th e effec t o f a napproximatel y 60 1 increas e i

nth e IntOH parameter . These , result s indicat e the approximat e magnitud e o f th e sensitivit y
o f th e maximum

reactivit y

o r maximu

m ozon e reactivit y

scale s t o th e condition s whic hwer e varie dinthes e scenarios . I t shoul db e recognized , however , tha t althoug hthey represen t a wid e rang e o f conditions , no t al l potentiall y

importan t aspect s o f airshe dscenario s wer e varied . Fo r example , the y

ar e al l singl e bo

xmode l scenarios , an di t i s no t clea r t o



### 3 4wha t exten t reactivitie s ma ydiffe r i f mor e complex , gridde d airshe d scenario s wer e used . Perhap s mor e significantl yi n term s o f direc t chemica l effect s o n reactivity , th e sam e mixtur e o f VOC s wa s use d t o represen t bas e cas e RO G emission s fo r al l scenarios
. Th e "allcit y average " mixtur e derive d b yJeffrie s e t al . (1989 ) wa s use d becaus e i t represent s ou r curren t bes t estimat e a s t o actua l VO C emission s i n urba n
areas , an d becaus e dat a ar e insufficien t t o unambiguousl yderiv e separat e mixture s fo r eac h th e scenarios
. However , th e aldehyd e fractio n o f thi s mixtur e i s highl yuncertain , an d th e compositio n o f ROG s i n emission s inventorie s i s significantl ydifferen t fro mthos e derive d fro manalysi s o f ai r qualit ydata . W e hav e found tha t usin g emissions-derive d RO G mixture s
ca n resul t i n non-negligibi e difference s i n calculate a reactivitie s (Wei r
e t al. , 1988) . Thes e uncertaintie s ar e no t reflecte d i n th e variabilitie s i n th e reactivitie s calculate d i n thi s study . I n thi s regard , i t shoul d b e note d tha t maximu mreactivit yscale s previousl yderive d an d distribute d b yth e autho r (Wei r e t al. , 1988 ; Carter , 1989 ; Low i and Carter , 1990 ) wer e base d primaril yo n calculation s usin g a n emissions-derive d mixtur e t o represen t bas e cas e RO G emissions
. Therefore , th e us e o f th e measurement-base d RO G mixture , whic h i s no w considere d t o b e preferabl e t o us e o f th e highl yuncertai n emission s data , represent s a departur e fro mthi s previou s work . Thi s result s i n somewha t lowe r relativ e reactivitie s o f formaldehyd e an d othe r radical-initiatin g specie s i n th e presen t maximu mreactivit yscal e tha n wa s th e cas e previously
. Th e effect s o n reactivit yo f varyin g th e compositio n o f th e bas e cas e RO G mixtur e i s bein g investigated , an d wil l b e reporte d i n a subsequen t paper .



### 3 5P.3 8

Aggregate dBas e Cas e Ozon e Reactivit y Scales , an

dCompariso nwit hthe Maximu m Reactivit y

andth e Maximu

m Ozon e Scale s Tabl e 5 summarize s th e result s o f the calculation s o f aggregate d relativ e reactivitie s fo r selecte drepresentativ e compound s fo r th e selecte dbas e cas e scenarios . Th e bas e cas e reactivitie s ar e quantifie d bot hb y ozon e yiel d(a s use dfo r th e maximu m reactivit y

andmaximu

m ozon e scales) , an

db y ozon e dose . Th e reactivitie s o f th e VOC s ar e give n relativ e t o tha t o f th e bas e cas e RO Gemissions , andthey ar e aggregate d eithe r b

y calculatin g th e averag e o f the ratio s fo r th e variou s scenarios , o r b y plottin g th e reactivitie s o f th e VO C agains t th e reactivitie s o f th e bas e cas e RO

Gsurrogate , andcalculatin g th e aggregate drati o a s th e slop e
o f th e leas t square s line , force dthroughzero . Example s o f thes e plot s fo r representativ e VOC s ar e show nonFigur e 5 . Eac hpoin t onthes e plot s correspon dt o on e o f th e city-day s use dt o calculat e th e bas e cas e reactivit y

scale . Th e plot s includ e line s whos e slope s indicat e th e aggregate dratio s derive dusin g bot hmethods , andals o line s whos e slope s sho w ratio s o f reactivitie s derive dusing th e maximu m reactivit y

an d maximu m ozon e scales , discusse dabove . Th e ratio s o f maximu m reactivitie s
andmaximu

m ozon e reactivitie s ar e als o include do nTabl e 5 , wher e the y
ca nbe compare dwit hth e aggregate dbas e cas e ratios . Compariso no f Ozon e Yiel dReactivities . Th e dat a onTabl e 5 an d Figur e 5 indicat e -that fo r som e compound s th e aggregatio nmetho dcanhav e
a significan t effec t onth e relativ e bas e cas e ozon e yiel dreactivities . Thi s sensitivit y

t o th e aggregatio nmetho di s du e t o th e sensitivit y o f reactivit y

ratio s t o th e R0G/N0 Xratio . Th e lin e fi t aggregatio ni s mor e sensitiv e t o th e scenario s wit hth e highe r reactivities , whic hi ngenera l reflec t th e lowe r N0 Xcondition s characteristi c o f th e maximu m reactivit y scale . Th e averag e rati o aggregatio ni s equall y sensitiv e t o al l


### 3 6scenarios , includin g thos e wit hvery lo w N0 Xlevel s andthu s lowe r reactivity . Figur e 6 show s a compariso no f th e aggregate dbas e cas e ozon e yiel d reactivitie s wit hth e maximu m reactivit y

andmaximu

m ozon e reactivit y scale s fo r al l th e mode l species . Thes e indicat e tha t th e bas e cas e ozon e yiel dreactivitie s aggregate dusin g the lin e fi t metho dcorrespon d reasonabl y

wel l t o th e maximu m reactivit y

scale , whil e th e bas e cas e yiel d reactivitie s aggregate dusin g th e averag e rati o metho dcorrespon dbette r t o th e maximu

m ozon e reactivities . Thi s i s expected , sinc e th e lin e fi t aggregatio nmetho di s mos t sensitiv e t o scenario s nea r maximu m reactivit y conditions . Onth e othe r hand , th e averag e R0G/N0 Xratio s fo r al l th e scenario s i s close r t o thos e fo r maximu m ozon e conditions , s o th e averag e rati o o f reactivities , wit hal l scenario s weighe dequally , woul db e close r t o maximu

m ozon e reactivities . Note , however , tha t ther e ar e fewe r case s
o f systemati c difference s amon g classe s o f compound s i nth e compariso n betwee nmaximu

m reactivitie s an

dlin e fi t bas e cas e reactivitie s tha ni s th e cas e fo r che compariso nbetwee nmaximu m ozon e reactivitie s an dthe averag e ratio . Compariso no f Ozon e Dos e Reactivities . Th e dat a o nTabl e 5 - and Figur e 5 als o includ e result s o f th e bas e cas e calculation s wher e reactivit y

i s quantifie db

y ozon e dose . Relativ e ozon e dos e reactivitie s tendt o b e les s sensitiv e t o th e condition s o f th e bas e cas e scenario s tha ni s th e cas e fo r ozon e yiel dreactivities . Thi s i s indicate db y th e standar ddeviation s o f th e aggregate daverag e reactivit y ratio s o r slope s
o f fitte dleas t square s line s give ninTabl e 5 , andals o b y th e fac t the aggregate dozon e dos e reactivitie s ar e muc hles s sensitiv e t o whic h aggregatio nmetho di s employed . Ther e ar e case s o f variabilitie s o f



### 3 7P.4 0

relativ e dos e reactivitie s amon g th e scenarios , particularl y fo r th e compound s wit hlo

w o r negativ e mechanisti c reactivity , whic hhav e th e mos t variabl e reactivitie s no matte r ho w they ar e quantifie do r aggregated . However , fo r mos t compound s th e scenario-to-scenari o variabilit y o f relativ e dos e reactivitie s i s muc hles s thani s th e cas e fo r ozon e yiel d reactivities . Figur e 7 show s a compariso no f the aggregate dbas e cas e ozon e dos e reactivitie s wit hthe maximu m reactivit y

an dmaximu

m ozon e reactivit y scale s fo r al l the mode l species . Thes e indicat e tha t th e bas e cas e ozon e dos e reactivitie s aggregate dusin g eithe r metho dcorrespon dreasonabl y wel l t o th e maximu

m reactivit y

scale , thoug hther e i s mor e scatte r whe n th e averag e rati o metho di s employed . Onthe othe r hand , the dos e reactivitie s correspondpoorl y wit hthe maximu

m ozon e reactivit y

scale . Thi s i s despit e the fac t that , fo r mos t o f the bas e cas e scenarios , the N0 Xlevel s ar e close r t o thos e o f maximu m ozon e condition s thanthos e yieldin g maximu

m VO C reactivities . Thes e result s sugges t tha t th e mechanisti c factor s tha t influenc e VO C reactivitie s unde r maximu m reactivit y

condition s ar e the same a s thos e whic hinfluenc e ozon e dos e reactivitie s unde r a muc hwide r se t o f conditions . Th e majo r characteristi c o f maximu m reactivit y

condition s i s tha t ozon e i s no t NO x -limited , andthe fina l ozon e yield s ar e determine d primaril y

b y ho w rapidl y

ozon e i s formed . Aspect s o f VOC s reactio n mechanism s whic haffec t ozon e formatio nrates , suc ha s thos e involvin g initiatin g o r inhibitin g radica l levels , therefor e ar e th e majo r factor s affectin g reactivit y unde r thos e condition s (Carte r an dAtkinson , 1989) . At lowe r N0 Xlevel s th e availability o f N0 Xbecome s a mor e importan t facto r affectin g ozon e yields , anda t sufficientl y lo w N0 Xth e rat e o f


## 3 8P.4 1

ozon e formatio n i s ultimatel yno t a majo r facto r i n affectin g ho wmuc h i s ultimatel yformed . However , th e ozon e formatio n rat e wil l affec t th e
ozon e dos e unde r practicall yan yse t o f conditions
. Eve n i n scenario s wher e ozon e i s ultimatel yN0 Xlimited , VOC s causin g mor e rapi d ozon e formatio n wil l resul t i n earlie r formatio n o f ozone , an d thu s highe r integrate d ozon e levels . Thu s th e goo d correspondenc e betwee n relativ e
ozon e dos e reactivitie s and maximu mreactivitie s i s no t unexpected .
Compariso n o f Incrementa l Reactivitie s wit h Reactivitie s Measure d b yth e O H Radica l Rat e Constan t Fo r man yVOCs , reactio n wit h O H radical s i s th e majo r proces s affectin g th e rat e a t whic h che yreac t i n th e atmospnere , an d thu s th e rat e a t whic h the yca n affec t ozon e formation
. Becaus e o f this , i t ha s bee n suggeste d tha t thi s rat e constan t ca n serv e a s a basi s fo r a VO C reactivit yscal e (e.g . Darnal l e t al. , 1976 ; ARB , 1989) . Thi s scal e ha s th e obviou s disadvantag e tha t i t ignore s othe r aspect s o f VOC s reactio n mechanism s whic h affec t ozon e formation , an d i t als o doe s no t tak e int o
accoun c th e fac t tha c i f cn e compoun d reacc s sufficiencl yrapidly , th e
amoun t o f VO C whic h react s i n th e atmosphere , an d thu s contribute s t o
ozon e formation , become s independen t o f th e rat e a t whic h i t reacts . Sinc e incrementa l reactivitie s tak e al l o f thes e factor s int o account , the yclearl yfor ma mor e Justifiabl e basi s fo r derivin g ozon e reactivit y scale s fo r VOCs . However , th e O H rat e constan t scal e ha s th e significan t advantag e tha t O H radica l rat e constant s ar e know n o r ca n be estimate d fo r
mos t o f th e type s o f VOC s emitte d int o th e atmospher e (Atkinson , 1989) , an d tha t i t ca n b e universall yapplie d unde r al l conditions
. Thus , i f i t
ca n b e show n t o giv e acceptabl e correlation s wit h reactivitie s quantifie d usin g mor e comprehensiv e methods , it s us e migh t b e appropriat e fo r som e


### 3 9P.4 2

type s o f applications . T o show ho w wel l a nO H radica l reactivit y scal e woul dcorrelat e wit h
on e base do nincrementa l reactivities , Figur e 8 show s plot s o f T=300 KO H radica l rat e constant s (kOH ) agains t incrementa l reactivitie s i nthe maximu m reactivit y

scal e fo r al l th e VOC s represente di nth e model . Sinc e th e reactivitie s ar e quantifie db y ozon e forme dpe r mas s o f VOC , the OH radica l rat e constant s ar e divide db y thei r molecula r weigh t to plac e the m
ona comparabl e basis . Plot s o f OH radica l rat e constant s agains t maximu m
ozon e reactivitie s o r the aggregate drelativ e reactivit y scale s loo k simila r t o Figur e 8 , an dar e no t shown . Figur e 8 show s tha t althoug hther e i s a correlationbetwee nkOH an d incrementa l reactivitie s fo r certai nhomologou s classe s o f compounds , suc h
a s th e alkene s an

dsome o f th e aromatics , the correlationbetwee n differen t type s o f VOC s i s extremel y poor . Inaddition , fo r th e homologou s serie s o f highe r n-alkanes , thre e i s a negativ e correlatio n betwee nthe kO H andincrementa l reactivity . Thus , althoug hther e ar e
case s wher e th e O H radica l rat e constan t correlate s reasonabl y wel l wit h reactivity , i ngenera l i t doe s no t appea r to be a reliabl e predicto r o f th e relativ e effec t o f the emission s o f a VO C onozon e formatio ninthe atmosphere .

Uncertaintie s i nChemica l Mechanism s Th e focu s o f thi s pape r ha s bee no nthe problem s o f developin g a singl e reactivit y

scal e give nthe variabilit y o f reactivitie s wit h environmenta l conditions . However , the dependencie s o f reactivitie s on environmenta l condition s i s no t th e onl y significan t sourc e o f uncertaint y i nth e developmen t o f VO C reactivit y scales . Uncertaintie s inou r



### 40knowledg e andabilit y t o mode l ozon e formatio nfro m th e gas-phas e atmospheri c reaction s o f VOC s ultimatel y limit s th e reliabilit y o f any VO C
ozon e reactivit y

scal e base donmode l calculations . Th e relativ e importanc e o f chemica l mechanisti c uncertaintie s varie s significantl y
amon g VOCs , an dthu s th e uncertaintie s inthei r calculate dreactivitie s
var y accordingly . Sinc e thi s pape r give s calculate dreactivitie s for a wid e variet y

o f compounds , i t i s necessar y t o plac e thes e result s in perspectiv e b

y discussin g an

drankin g the relativ e level s o f uncertaint y i nth e chemica l mechanis m use dt o calculat e thei r reactivities . Thi s mus t b e take nint o accoun t whe nthes e o r an y othe r calculate dreactivit y scale s
ar e use di nassessin g effect s o f VOC s onozon e formation . Ther e ha s inrecen t year s bee nsufficien t advance s i nou r understandin g i nth e gas-phas e reaction s involve di nth e formatio no f
ozon e inphotochemica l smog , tha t modelin g thes e processe s i s becomin g a viabl e approac hfo r contro l strateg y plannin g purposes . Thi s ha s bee n mad e possibl e no t onl y fro m th e larg e bod

y o f fundamenta l kineti c an d mechanisti c dat a concernin g th e individua l reaction s (e.g. , se e Atkinson , 1990 , andreference s therein) , bu t als o fro m availabilit y

o f environmenta l chambe r experiment s suitabl e fo r testin g the prediction s o f thes e mechanisms . Thi s ha s resulte dina convergenc e o f th e airshe dmode l mechanism s develope db y differen t group s i nrecen t years , wit hdifference s i nth e prediction s o f th e mos t recen t mechanism s i nsimulation s o f ozon e formatio ni nmixture s representin g pollute durba natmosphere s bein g relativel y

smal l (Hough , 1988 ; Dodge , 1990) . Indeed , man y i f no t mos t airshe dmodeler s now believ e tha t i t i s uncertaintie s inth e emission s data , rathe r tha ni nth e chemica l mechanisms , whic hcaus e th e majo r uncertaintie s limitin g th e reliabilit y o f prediction s o f curren t airshe d



### 4 1P.4 4

model s a s they

relat e t o chemica l transformations . However , predictin g relativ e ozon e reactivitie s o f the differen t individua l VOC s i s a mor e difficul t problem thanpredictin g ozon e formatio nfro

m the mixtur e o f VOC s generall y presen t i

nurba n atmospheres . Th e latte r ha s bee nth e focu s o f muc ho f th e previou s mechanis m

developmen t work , wher e condense dmechanism s hav e bee ndevelope d t o efficientl y

represen t realisti c atmospheri c mixtures , andhav e bee n teste dagains t chambe r experiment s usin g suc hmixture s (e.g. , Ger y e t al. , 1988 ; Carte r andLurmann , 1990b) . Th e mechanis m employe di nthi s stud y differ s fro

m thes e i

nattemptin g t o represen t the reaction s o f a larg e numbe r o f th e differen t type s o f individua l VOC s (Carter , 1990) . A s discusse dinit s documentatio n(Carter , 1990) , the leve l o f knowledg e upo n whic hthi s mechanis m i s base dvarie s considerabl y amon g th e compound s i t represents . Thi s result s incorrespondin g variabilitie s inth e degre e o f uncertaint y

inprediction s o f reactivitie s o f thes e compound s regardles s
o f the type s o f scenario s o r aggregatio nmethod s employed . Th e level s o f uncertaint y i nth e reactio nmechanis m obviousl y

mus t b e take nint o accoun t whe nusin g the result s o f mode l calculation s o f reactivitie s t o asses s ozon e contro l strategies . T o ai di nsuc h assessments , al l the VOC s liste do nTabl e 4 hav e bee ncategorize dina six-clas s groupin g accordin g t o th e author' s qualitativ e assessmen t o f th e leve l o f ou r presen t knowledg e o f thei r atmospheri c reactio nmechanisms , an dth e availabilit y o f environmenta l chambe r dat a suitabl e fo r testin g thes e mechanisms . Thus , thes e shoul dgiv e a roughindicatio no f th e degre e o f uncertaint y i nthei r prediction s o f reactivitie s i nan y give n scenario . Thes e grouping s ar e a s follows :



### 42Grou p1 : Compound s fo r whic hw e believ e we understanda t leas t th e mos t importan t o f th e fundamenta l processe s b y whic hth e VO C promote s ozon e formation , andwhos e mechanism s hav e bee nteste da t leas t t o som e exten t usin g environmenta l chambe r data . Example s includ e n-butane , ethylene , formaldehyd e andmethanol . Ther e ar e stil l som e uncertaintie s fo r mos t o f th e compound s i nthi s group , bu t new dat a ar e no t expecte dt o hav e majo r impact s onprediction s o f thei r reactivity .

Grou p2 : Compound s fo r whic hw e believ e w

e understan dthe majo r reaction s involvin g ozon e formatio nreasonabl y wel l base donfundamenta l knowledge , bu t whos e mechanism s hav e no t bee nteste dagains t chambe r data . Example s includ e th e C-\-C? alkane s an dethanol .

Grou p3 : Compound s wher e ther e ar e majo r gap s inou r knowledg e i nthei r mechanism s involve di nozon e formation , bu t fo r whic havailabl e environmenta l chambe r dat a ha s allowe du s t o develo padjuste do r parameterize dmechanism s whic hcanadequatel y simulat e ozon e formatio nan d othe r observation s i nthes e experiments . Example s includ e severa l representativ e aromati c compounds , propene , 1-buten e an d1-hexene .

Grou p4 : Compound s whic hhav e uncertai nmechanism s an dfo r whic hther e
ar e onl y

limite do r unreliabl e chambe r dat a availabl e fo r testin g o r adjustin g thei r mechanisms . Example s includ e severa l Ce + alkanes , propionaldehyde , acetone , methylethy l ketone , an dacetylene . I

naddition , thi s grou pi s als o use dfo r isopren e andacrolein , fo r whic hther e ar e probabl y

enoug hchambe r dat a t o plac e th e compoundi nGrou p3 * bu t fo r whic hth e curren t mechanis m doe s no t hav e sufficien t detai l t o simulat e



### 43thes e dat a a s wel l a s i t could . [ A mor e detaile disopren e mechanism , whic hshoul dqualif y fo r Grou p3 , i s bein g develope d(Carte r an dAtkinson , unpublishe dresults) , bu t ha s no t ye t bee nincorporate dint o the presen t mechanism. ]

Group s 5 and6 : Compound s whos e mechanism s ar e uncertai nandfo r whic hn o adequat e chambe r dat a ar e available . Mechanism s fo r thes e hav e been estimate dbase donanalog y o r extrapolatio nfro m mechanism s develope dfo r othe r compounds . Tw o categorie s ar e use dt o expres s the author' s qualitativ e estimat e concernin g the relativ e degre e o f uncertaint y i nthe estimate dmechanism , wit h6 bein g th e mos t uncertain . Example s o f compound s inth e categor y 5 includ e the C^-C^ alcohol s an dth e highe r (C <C J n-alkanes ; example s i ncategor y 6 compound s liste do nTabl e 4 includ e the hig hmolecula r weigh t alkenes , methy l acetylene , highe r molecula r weigh t aromatics , an dC^ * alkanes . As discusse dabove , reactivitie s o f VOC s canbe broke ndow nint o tw

o components : thei r kineti c reactivity , whic hreflect s ho w rapidl y

the VO C reacts , an

dthei r mechanisti c reactivity , whic hreflect s th e amoun t o f
ozon e forme donc e th e VO C reacts . Sinc e the rat e constant s fo r the majo r atmospheri c consumptio nreaction s hav e bee nmeasure dfo r man y VOC s (Atkinson , 198 9 andreference s therein ) andcanb e estimate dfo r mos t other s (Atkinson , 1987) , the majo r uncertaintie s inthe VOC s reactio n mechanis m

ar e thos e whic hreflec t thei r mechanisti c reactivities . Thu s th e categorizatio nabov e ca nb e though t o f a s applyin g onl y t o the mechanisti c reactivit y estimates , sinc e thi s i s almos t alway s th e mos t uncertai naspect s o f prediction s o f reactivit y o f a give nVO C i na give n scenario .



### 44P.4 7

I f reactivitie s coul dbe . measure ddirectl y i nenvironmenta l chambe r experiments , the nsuc hexperiment s coul db e use dinstea do f mode l calculation s t o deriv e reactivit y scales . However , a s discusse d previousl y

(Carte r andAtkinson , 1989) , reactivitie s measure dinchambe r experiment s ar e no t th e same a s thos e i nthe atmosphere . Thi s i s becaus e chambe r effect s impac t the result s o f suc hexperiment s (Bufalin i e t al. , 1972,1977 ; W

ue t al. , 1976 , Carte r e t al. , 1979,1982,1986 ; Carte r an d Lurmann , 1990a) , andbecaus e i t i s no t practica l t o simultaneousl y duplicat e al l o f th e airshe dcondition s whic hmigh t affec t reactivity . O n th e othe r hand , chambe r experiment s ar e clearl y usefu l t o th e developmen t
o f th e chemica l mechanism s use di nmode l calculation s o f reactivity , an d provid e th e onl y

practica l mean s t o tes t whethe r th e mechanis m ha s majo r
error s o r emission s whic hwoul dinvalidat e it s prediction s o f reactivit y i nmode l calculations . I naddition , chambe r experiment s migh t b e usefu l fo r th e direc t measuremen t o f mechanisti c reactivitie s o f VOCs , whic ha s indicate dabov e i s th e mos t uncertai ncomponen t i natmospheri c reactivit y estimates . Th e potentia l utilit y o f chambe r experiment s fo r thi s purpose , whic hshow s promis e a s a mean s t o significantl y reduc e mechanisti c uncertaintie s i nreactivit y scales , i s unde r investigatio ninou r laboratories .



### 4 5P.4 8

SUMMAR YAN D CONCLUSION S

A quantitativ e reactivit y scal e whic hcompare s the effect s o f differen t type s o f VOC s onozon e formatio nwoul db e a usefu l too l for developin g effectiv e an dflexibl e contro l strategie s fo r ozon e formation . However , the developmen t o f suc ha scal e ha s a numbe r o f difficulties , whic hcanb e categorize dint o thre e majo r areas . Th e firs t
concern s th e fac t tha t the gas-phas e chemica l mechanism s b y whic hVOC s
reac t i nth e atmospher e t o for m ozon e ar e i

nmany case s highl y uncertain . Thi s result s i nuncertaintie s i

nthe mode l prediction s o f the reactivit y

o f a VO C inan

y give nscenario . Th e secondconcern s th e fac t tha t th e effect s o f VOC s o nozon e formatio nandthei r reactivitie s depen d significantl y

o nthe environmen t inwhic hthe y ar e emitted . Thi s mean s tha t eveni f we ar e capabl e o f reliabl y predictin g the reactivit y o f a se t
o f VOC s ina se t o f scenarios , i t i s no t obviou s ho w thes e result s shoul d b e use dindevelopin g a singl e reactivit y scale , o r eve nwhethe r a us e o f
a singl e reactivit y scal e ha s an

y scientifi c or regulator y validity . Th e thir dproble m

concern s the fac t tha t ther e ar e uncertaintie s i ncondition s
o f airshed s andepisode s wher e unacceptabl e level s o f ozon e ar e formed . Th e uncertaintie s i ncondition s o f a specifi c episod e affec t prediction s
o f VO C reactivitie s fo r tha t episode , anduncertaintie s indistributio no f condition s affec t th e developmen t o f appropriat e method s fo r aggregating scenario-specifi c reactivitie s int o a generalize dreactivit y scale . Th e focu s o f thi s pape r ha s bee nprimaril y onthe secon do f thes e thre e problems , tha t o f derivin g a singl e reactivit y scal e give ntha t reactivitie s depen donenvironmenta l conditions . Thi s ha s bee nstudie db y derivin g reactivit y scale s using severa l differen t techniques , give na



### 4 6P.4 9

singl e chemica l mechanis m an da singl e se t o f representativ e airshe d scenarios . Th e chemica l mechanis m employe dmay

b e uncertai nfo r many VOCs , bu t i t incorporate s ou r curren t bes t estimat e o f thei r atmospheri c reactions , an drepresent s mos t o f the majo r type s o f specie s whic hnee dt o b e incorporate dinreactivit y scales . Th e se t o f representativ e environmenta l scenario s employe dmay b e eve nmor e uncertain , bu t they represen t thei r developers ' bes t estimat e o f th e condition s o f a wid e variet y o f representativ e pollutio nepisode s give nth e limitation s in availabl e dat a andth e constraint s o f th e simplifie dphysica l formulatio n
o f th e city-specifi c EKM A model . Thi s i s considere dt o b e sufficien t fo r th e purpos e o f evaluatin g method s fo r derivin g reactivit y scales . Difference s i nrelativ e level s o f N0 X(usuall y measure db

y th e ROG/NO xratio ) i s th e mos t importan t reaso nfo r difference s of . VO C reactivitie s fro

m scenario-tp-scenario . Th e maximu m reactivit y

scal e represent s reactivitie s unde r th e lowes t ROG/NO xcondition s whic hi s appropriat e fo r derivin g a nozon e reactivit y scal e becaus e i f ROG/NO x ratio s wer e muc hlower , N0 Xinhibitio nwoul dpreven t significan t amount s
o f ozon e fro

m bein g forme di na one-day episode . Th e maximu m ozon e reactivit y

scal e represent s th e highes t R0G/N0 xcondition s appropriat e fo r VO C reactivit y

assessmen t because , i f the ratio s wer e any higher , ozon e formatio nwoul db e N0 Xlimited . Unde r NO x -limite d condition s VO C contro l i s ineffectiv e fo r reducin g ozone , an dthu s VO C reactivitie s ar e irrelevant . Therefor e compariso no f relativ e reactivitie s calculate d usin g thes e tw

o scale s giv e a nappropriat e indicatio no f th e maximu m importanc e o f uncertaintie s i nth e R0G/N0 xrati o inreactivit y predictions .



### 4 7P-5 0 .

Consisten t wit hresult s o f previou s studies , i t wa s foundtha t the N0 Xcondition s significantl y affecte dbot habsolut e andrelativ e reactivities . Absolut e reactivitie s ar e the mos t strongl y affected , bu t difference s i nrelativ e reactivitie s ar e mor e significan t inpractica l VO C contro l strateg y

assessmen t applications . Relativ e reactivitie s amon g the
same chemica l clas s o f VO C ar e no t strongl y affecte db

y th e ROG/NO xratio , (a t leas t whe ni t i s varie dbetwee nthe maximu m reactivit y

andmaximu

m
ozon e range) , bu t relativ e reactivitie s o f differen t chemica l classe s o f

r- VOC s ca nb e quit e different . Ingeneral , th e ratio s o f reactivitie s o f aromatic s andalkene s relativ e t o thos e o f alkanes , C O an dsome alcohol s
ar e significantl y

lowe r unde r lo

w N0 X , maximu

m ozon e condition s tha nunde r ^relativel y

hig hN0 X , maximu

m VO C reactivit y

conditions . Thi s make s a difference , fo r example , i nprediction s o f the ozon e benefit s o f us e o f reformulate dgasoline s whic hreduc e vehicl e emission s o f alkene s and aromatic s relativ e t o thos e o f alkanes . Th e maximu m ozon e reactivit y scal e predict s muc hles s benefi t o f us e o f suc hfuel s tha nwoul dthe maximu m reactivit y

scale . Thi s ha s a practica l effec t i nassessin g th

e relativ e advantage s o f reformulate dgasoline s a s oppose dt o methano l o r othe r alternativ e fuels . Derivin g reactivit y scale s b

y aggregatin g reactivitie s calculate dfo r
a nappropriat e distributio no f actua l ozon e pollutio nepisode s i s a n appealin g approac hbecaus e i t ca npotentiall y b e base do nprediction s o f th e mos t accurat e model s fo r condition s o f thos e episodes . However , i t i s
no t currentl y

practica l fo r a numbe r o f reasons . I nth e firs t place , becaus e o f majo r uncertaintie s i nemission s inventorie s andbackgroundan d boundar y

pollutan t levels , we ma y no t hav e accurat e model s fo r any rea l pollutio nepisodes , eve nthos e whic hhav e bee nth e mos t extensivel y



### 48studie dandmodeled . Thes e uncertaintie s als o mak e i t difficul t t o

determin e a nappropriat e distributio no f episode s t o us e fo r reactivit y
assessmen t purposes . Inaddition , accurat e representatio no f condition s
o f "rea l world " episode s requir e comple xgridde dairshe dmodels , whic har e expensiv e t o ru

nan dhav e larg e inpu t dat a requirements . Furthermore , becaus e o f presen t compute r constraints , suc hmodel s ca ncalculat e reactivitie s fo r onl y a limite dnumbe r o f compounds . Finally , eve ni f on e determine da nappropriat e distributio no f episode s an dcoul daccuratel y mode l them , i t i s no t immediatel y obviou s wha t i s th e mos t appropriat e way t o aggregat e th e result s fo r th e variou s scenario s t o yiel da singl e scale . Th e result s o f thi s stud y indicat e tha t th e aggregatio nmetho dca nb e importan t i naffectin g reactivit y scale s derive dfro m scenario s representin g a distributio no f airshe dconditions . I f th e reactivitie s
ar e aggregate dsimpl y b y averagin g ratio s o f reactivitie s calculate dfo r th e individua l scenarios , on e obtain s relativ e reactivitie s whic har e simila r t o thos e inth e maximu m ozon e reactivit y

scale . O nth e othe r hand , i f th e reactivitie s ar e aggregate dusin g a metho dwhic hgiv e greate r weigh t t o scenario s wher e VOC s hav e greate r effect s onozone , suc ha s b y minimizin g error s inprediction s o f absolut e effect s o nozon e formatio n throughou t th e entir e se t (a s i s th e cas e wit hthe "lin e fit " method) , the relativ e reactivitie s obtaine dar e lik e thos e i nthe maximu m reactivit y scale . A s indicate dabove , thes e tw o ar e insome case s significantl y differen t i nprediction s o f relativ e reactivity . Th e aggregatio nmetho dappear s t o b e les s importan t i f ozon e impact s
ar e quantifie db

y integrate dozon e concentratio n(ozon e dose ) rathe r than b y th e tota l yield s o f ozon e formed . Thi s i s a nencouragin g result ,


## 4 9P.5 2

becaus e i t suggest s tha t a singl e reactivit y scal e ma

y be applicabl e t o measurin g effect s o f VOC s o nozon e exposur e i

na wid e variet y

o f airsheds . Inaddition , the relativ e reactivitie s inthe aggregate dozon e dos e scale s correspon dreasonabl y wel l t o thos e i nthe maximu m reactivit y scale . Thi s i s becaus e integrate dozon e concentrations , lik e ozon e yield s i nhig hN0 Xmaximu

m reactivit y

conditions , ar e bot hsignificantl y affected , b y ozon e formatio nrates . Thi s i s th e cas e eve nfo r scenario s wher e ozon e formatio ni s N0 Xlimited , wher e th e ultimat e ozon e yiel di s relativel y insensitiv e t o ho

w rapidl y

ozon e i s formed . Base donthes e considerations , i t i s conclude dtha t i f on e need s t o
us e a singl e generalize dreactivit y scal e fo r assessin g effect s o f VOC s o n
ozone , a maximu

m reactivit y

scal e i s the mos t appropriat e fo r thi s purpose , a t leas t fo r the nea r term . I t i s no t a s sensitiv e t o the distributio no f airshe dscenario s use dt o deriv e i t a s i s the cas e fo r aggregate dbas e cas e reactivit y scales , an

dca nb e calculate dusin g relativel y

simpl e airshe dmodel s withou t havin g t o accuratel y simulat e any particula r ai r pollutio nepisode . Althoug hn o singl e reactivit y scal e wil l perfectl y

represen t al l conditions , the maximu m reactivit y

scal e
seem s t o giv e a reasonabl y clos e correspondenc e t o relativ e ozon e impact s
o f VOC s i na wid e numbe r o f cases , particularl y thos e wher e th e impact s o f VOC s ar e th e largest . Th e presen t result s als o sugges t tha t th e maximu m reactivit y

scal e migh t giv e appropriat e prediction s o f effect s o f VOC s change s o nozon e exposur e eve ni nscenario s wher e they d o no t accuratel y predic t effect s o npea k ozon e levels . Althoug hthes e conclusion s ar e base donreactivitie s calculate dfo r highl y simplifie dandperhap s i nsome
case s inaccurat e scenarios , the scenario s employe dar e sufficientl y varie d tha t i t i s no t unreasonabl e t o expec t tha t simila r result s woul db e



### 5 0P.5 3

obtaine di f mor e detaile dandaccurat e scenario s wer e employed . However , i t i s clea r tha t furthe r researc hi s neede dt o reduc e th e uncertaintie s i nth e derivatio no f VO C reactivit y scales . Th e scenario s employe di nthi s stud y may no t represen t th e bes t currentl y availabl e estimat e o f th e distributio no f ozon e pollutio nconditions , an dmor e wor k i nthi s are a i s clearl y needed . A

systemati c study

o f th e effect s o f airshe dcondition s othe r thanN0 Xavailabilit y o nreactivit y

woul dai di

n thi s effort . I t woul dindicat e whic hscenari o characteristic s ar e the
mos t importan t t o accuratel y represen t whe ncalculatin g maximu m reactivity , andwoul dassis t i nestimate s o f uncertaintie s i nreactivit y prediction s cause db y uncertaintie s incharacterizin g airshe d conditions . Thi s include s studie s o f th e sensitivit y o f reactivit y prediction s o nchange s i ncompositio no f th e bas e cas e RO Gsurrogate , whic har e presentl y underwa y

i nou r laboratories , andwhic hwil l be reporte di na subsequen t paper . Inaddition , th e predictio ntha t maximu m reactivitie s wil l correspon dreasonabl y wel l t o effect s o f VOC s o nozon e exposur e need s t o be teste dusing realistic , gridde dairshe dmodels . Suc h test s ar e presentl y underway , an

dpreliminar y

result s ten

dt o suppor t the genera l utilit y

o f th e maximu

m reactivit y

scal e (Russel , 1990) . I t shoul dals o b e recognize dtha t regardles s o f whic happroac ho r se t
o f airshe dcondition s i s use dfo r developin g a reactivit y scale , the reactivitie s fo r many VOC s wil l be uncertai nbecaus e o f uncertaintie s i n th e chemica l mechanis m use dt o calculat e them . Onl y fo r a limite dnumbe r
o f VOC s ar e sufficien t dat a availabl e t o tes t thes e mechanisms . Modelin g studie s ma y

giv e us a nindicatio no f the magnitude s o f th e effect s o f thes e uncertainties , bu t wil l no t reduc e them . T o reduc e thes e uncertainties , experimenta l dat a ar e neede dt o tes t th e mechanism s use dt o



### 5 1P.5 4

deriv e th e reactivit y factors , o r a t a minimu m t o tes t thei r prediction s
o f maximu

m reactivity . W

e ar e currentl y

investigatin g experimenta l approache s whic hca nbe use dt o reduc e chemica l uncertaintie s i nVO C reactivit y

scales .



### 52P.5 5

Acknowledgement s

Th e author wishe s t o than k Drs . Michae l W . Ger yan d Gar yZ . Whitte n fo r providin g computer-readabl e inpu t file s fo r th e scenario s employe d i n thi s stud yan d Dr . Roge r Atkinson , Mr . Bar t Croe s an d Mr . Alvi n Lowi , Jr . fo r helpfu l discussions
. Thi s wor k wa s supporte d primaril yb yth e U.S . Environmenta l Protectio n agenc ythroug h Cooperativ e Agreemen t No . R-814396-01-0 . Additiona l suppor t wa s provide d b ycontract s wit h th e Californi a Sout h Coas t Ai r Qualit yManagemen t District , th e Californi a Ai r Resource s Boar d (Contrac t No . A932-094) , an d a consultin g contrac t fo r th e Wester n Liqui d Ga s Association
. However , thi s pape r ha s no t bee n reviewe d
o r approve d b

yanyo f thes e agencie s o r organizations , an d th e opinion s and conclusion s give n herei n ar e entirel ythos e o f th e author .



### 5 3P.5 6

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### 5 5P.5 8

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### 5 6P.5 9

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### 5 7P.6 0

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### 5 8P.6 1

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### 5 9P.6 2

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### 6 0P.6 3

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### 6 1P.6 4

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—o •» « i -i «- > i t »

- ~ A ^ o — • D W C I B )

O "Tabl e
ID la ]

G-MA 1 G-MA 2 G-MA 3 G-MA1 W-HA 1 G-MA5 G-MA6 G-MA 7
G-NA1 G-NA 2 G-NA 3 G-NAl G-NA 5 G-NA 6 G-NA 7 G-NA 8 W-NA 8 G-NA 9
G-NY 1 G-NY 2
G-PH 1 G-PH 2 G-PH U G-PH 5 G-PH 6 G-PH 7 G-PH 8 1 . Summar

y o f th e H a Cit y an d Sit e

Massachusett s Nashu a Nashu a Nashu a Nashu a Nashu a Lexingto

n Lexingto

n Nashvill e Nashvill e HealthCenter Hendersonvl1i e HealthCenter Hendersonvl1l e Healt hCente r Hendersonvl1l e Hendersonvl1l e

(Sam e a s Hendersonvl1l e Ne w Yor k Stratfor

d Middletow

n Philadelphi a (not given ) (no t given ) Trento n (no t given ) (no t given ) Roxboroug

h Roxboroug

h MA

Y JU L AU G AU G |o r
Uat

30 . 21 . 13 , 15 , G-MA1 ) AU G JU N JU L
JU L JU L JU L AU G AU G AU G AU G SEP 16 . 29 , 10 ,
2 , 25 . 25 , 1 , 1 , 10 , 10 , 11 , C-NA8 ) SEP
JU N JU N

JU L JU L JU N JU N AU G JU N JU N 12 . 21 . 21 ,
13 . 19 , 15 , 16 , 19 . 27 . 27 , Chara c

e

197 8 197 8 197 8 197 8 197 8 197 9 197 9
198 0 198 0 198 0 198 0 198 0 198 0 198 0 198 1 198 1
i96 0 198 0
197 9 197 9 198 1 198 1 198 2 198 3 198 3 terlstlc s Calc . ma x0-> (ppb )

12 7 10 7 11 7 12 5 13 1 10 9 11 3 11 0
8 8 8 6 9 7 7 6 8 7 12 0 13 1 8 5 13 7 8 0
21 8 22 6
23 3 15 1 15 1 20 8 13 1 19 8 17 3 o f th

e R0C/N0 v Ib |

6. 1 11. 7 6. 3 6. 1 6. 1 8. 5 6. 0 '7. 1
11. 6 19 1 11. 7 18. 9 11. 5 10. 6 9 . 1 11. 0 11. 0 12. 9
12. 8 10. 8
6. 8 6. 1 8. 3 8. 2 8. 0 6. 3 5 7 EKM

A S c Ligh t Ic )

21 0 21 9 23 8 22 7 22 7 22 3 25 5 23 7
23 0 22 3 22 3 22 0 22 0 21 5 21 5 18 8 18 1 18 7
23 8 23 8
23 6 21 3 21 1 23 9 21 0 21 2 21 2 enarlo s

Inv . Use

d f Heigh t (meters ) lnlt .

25 0 25 0 25 0 25 0 25 0 25 0 11 9 36 0
25 0 25 0 25 0 25 0 25 0 25 0 25 0 25 0 25 0 25 0
30 0 30 0
25 0 25 0 25 0 25 0 25 0 25 0 25 0 Fina l

57 1 185 0 12 7 58 0 53 6 89 3 86 7 170 4
181 5 181 5 181 5 1811 5 181 5 18*1 5 181 5 181) 5 181 5 181 5

156 1 156 1

113 5 87 1 168 2 121 1 165 9 99 6 99 6 o r Reactivit y Assessment . 2

- - Inpu t flu x(m.mol/ m ) ( * inpu t emitted)|d ] - -

-- - II C -- -

5.1 5 (10J ) 3 1 2 (25* ) 5.0 0 (35» ) 5.2 6 (38» ) 5.1 3 (38* ) 3 0 5 (23%) 1.6 0 (21? ) 37 1 (25* )
2.8 1 ( 7» ) 18 7 ( 9* ) 251 (23* ) 19 6 ( 9* ) 2.6 7 (23* ) 1 5 8 ( 91 ) 6.0 0 (23* ) 1.1 1 (23* ) 1.1 1 (23* ) 3 1 3 (23X )
312 1 (28» ) 32.1 1 (21* )
18.2 3 (19* ) 50.2 3 (81* ) 16.3 7 (13» ) 113 5 (38» ) 10.8 8 (15* ) 17.5 8 (17* ) 19.1 1 (52* ) — NO x—

0.9 9 0.1 9 0.8 5 6.9 5 0.9 5 0.1 8 0.8 8 0.8 0
0.5 9 0.1 0 0.5 7 0.1 1 0.5 9 0.9 8 1.31 0.9 3 0.9 3 0.6 9
2.7 8 31 5
2.8 9 8.3 8 3.0 2 2.8 3 1.7 2 3.2 6 3.6 0 (65* ) (32* ) (59* ) (61* ) (61* ) (30* ) (52J ) (58* )
( 7» ) ( 9* ) (21» ) ( 91 ) (21* ) ( 9* ) (21» ) (21* ) (21J ) (21J ) (16* ) (53X )
(56* ) (85* ) (58» ) (17* ) (26» ) (61* ) (65* ) , - - Alof t

- - H C - - (ppb ) (* )

1 0 ( 9* ) 1 0 (15* ) 1 0 ( 5* ) 1 0 ( 9* ) 8 0 (15* ) 1 0 (26* ) 1 0 (13» ) 1 0 (37* )
9 0 (67* ) 9 0 (76* ) 9 0 (69* ) 9 0 (75* ) 9 0 (69X ) 9 0 (56* ) 9 0 (19* ) 9 0 (57* ) 9 0 (57* ) 9 0 (65* )
1 0 ( 6* ) 1 0 ( 6* )
1 0 ( 7* ) 1 0 ( 2* ) 15 0 (35* ) 22 5 (38* ) 5 0 (21* ) 10 0 (15* ) 1 0 ( 6* ) le j -



### ° 3 (ppb )

3 3 8 1 2 1 5 6 6 0 6 0 5 6 6 3
1 5 3 5 3 5 1 3 1 3 1 2 1 2 1 10 0 6
8 0 8 0
10 5 3 2 1 0 1 0 6 0 6 5 6 5 Note s

H I H 1

H I

H I

H,g l Ig l

If ) 

## i n ! con t 1 nue<l )Tabl e 1 . (continued ) - 3
I D [a ]

G-WA 1 G-WA2 G-WA3 G-WA 1 W-WA1 G-WA5
W-CH 1
U-SL 1

W-LA1
W-SF 1 N-SF 2

EKMA- 1 EKMA- 2 EKMA- 3 Cit

y an d Sit e

Washingto

n Takom a Takom a Takom a Takom a (Sam e a s Takom a Chicago Kenosh a St . Loui s (not given ) Lo s Angele s Glendor a Sa nFrancisc o (not given ) (not given ) Da t

. JU L 16 , JU L 17 , JU L 21 , AU G 7 , G-WA1 ) AU G 29 ,
JU L 11 ,
JU N 21 ,
AU G 21 ,
SE P 30 , JU L 12 , Standar d EKM A Scenario s Lo s Angeles(k ) Lo s Angelesfk ) Lo s Angeles!k ) Jun e 2 1 Jun e 2 1 June 2 1 B

198 0

198 0 198 0 198 0 198 0
197 9
198 6
198 5
198 0 198 1 Calc . ma x0- s (ppb T

11 7 111 13 8 16 1 16 7 10 8
17 8
16 5
36 7
20 6 21 0
21 9 111 10 1 ROG/NO .

lb )

7. 9 12. 5 7. 9 7. 2 6. 9 6. 0
7. 1
8. 3
8. 8
12. 8 10 . 1
10. 2 8. 7 8. 6 Light

Ic )

19 1 19 0 18 9 19 8 19 8 16 3
23 3
21 5
23 1
17 5 26 5
25 1 25 1 25 1 Inv . Heigh

t (meters ) Init .

16 0 16 0 16 0 12 0 12 0 15 0
25 0
25 0
25 0
8 9 8 9
25 0 25 0 25 0 Final

212 8 212 8 212 8 165 8 165 8 222 9
88 0
170 0
70 0
10 0 10 0
60 0 150 0 350 0 - - I

n ( X1 .- .

6.8 1 6.6 8 10.7 7 16.2 2 16.2 2 16.6 1
7.1 3

13 . 1 6

21.8 7
91 7 6.2 2

12.0 0 12.0 0 12.0 0 pu

t flux(m.mol/ m

) , ipu t e m H C

(28» ) (26* ) (50* ) (13* ) (13* ) (57* )
(19* )
(23* )
(30» )
(71* ) (71* ) (33* ) (33* ) (33» ) ltted)|d ) - -

— NO x—

1.2 6 0.7 9 1.7 7 2.5 2 2.5 2 3.3 1

1.3 5
1.8 0

2.7 0

0.9 1 0.7 8

1.2 0 1.5 0 1.7 0 (10* ) (37* ) (71* ) (57* ) (57* ) (73* )
(58* )
(11* )
(51* )
(21* ) (21J )
(11* ) (11* ) (11* ) Alor t

HC - - (ppb ) (* )

1 0 1 0 1 0 1 0 2 5 1 0
10 0
3 0
10 0
25 0 17 0
2 0 2 0 2 0 (32* ) (32* ) (23* ) (11* ) ( 7* ) (17* )
(26* )
(12* )
( 8> )
(26J ) (26* )
( 2* ) ( 8* ) (18* ) le ) - 

### ° 3 (ppb )

6 5 6 5 6 5 5 6 6 0 6 5
6 0
5 0
10 0
6 1 6 1
7 0 7 0 7 0 Note s

If )



### I D
I D ir )
If ) l.r.il ir. D 

### Ul IJ ] U J
Notes : (a ] Scenario s withprefi x"G- " fro m Ger y et al . (1987) ; thos e wit h"W- " are fro

m Whittene

t al . (1988) ; an

d thos e wit

h "EKMA- " ar e fro

m Gipso nan d Frea s (1983 ) modified a s describe d b y Carter an

d Atkinso

n(1989) . Se e thes e reference s fo r mor e complet e descriptio no f inpu

t dat a fo

r thes e scenarios . (b ] Tabulated Hydrocarbon/N O l s rati o o f fina l hydrocarbo nan d N0

_concentratio

na t th e en d o f th e simulatio

ni f n o chemica l reactio noccurrs . Include s hydrocarbon s an d (where applicable ) N0 Xentraine d fro m aloft . (c ] "Light " l s Integrate d NO nphotolysi s rat e fo r th e simulatio

n(i t l s a unltles s quantity) . |d j Tota l Initia l an d emitte

d Hydrocarbo

nan d N O inpu t (excludin

g specie s entraine

d fro m aloft ) are give

ni nterm s o f effectiv

e number s o f mole s (o r mole s carbo

nTo r HC ) inpu

t int o th e cel l pe r uni t area . Th e valu e l nparenthese s I s th e percentag e o f th

e mola r Inpu t whic hl s present InitialIv .Tabl e 2 .

See nI D 

### [a ] Calculate d RO

Scenarios .
ROG / 

### N0 X

Massachusett s Avg . S.Dev .

• G-MA 1 G-MA 2 * G-MA 3 G-MA l W-MA l G-MA 5 G-MA 6 • G-MA 7 Nashvill e Avg . S.Dev . G-NA 1 • G-NA 2 G-NA 3 G-NA 1 G-NA 5 • G-NA 6 G-NA 7 G-NA 8 • H-NA 8 G-NA 9 

### 5. 0

1. 1 6. 0 3. 5 7. 0 6. 0 6. 0 1. 0 

## l. o 3- 5
6. 1 1. 1 6. 0 5. 0 5. 0 6. 0 6. 0 5. 0 6. 0 8. 0 6. 0 8. 0 Max . 

## ° 3 (ppb )



### 1 in
. 

### 14 . 126 . 108 . 135 . 122 . 122 . 

### 96 . 101 . 

### 99 . 88 . 21 . 86 . 82 . 83 . 73 . 76 . 90 . 117 . 

### 73 . 131 . 

### 69 . G/N0 XRatio s an d Selecte d

Bas e RO G React' y (Og/ppraC )

0.7 5 0.0 9 0.7 1 0.7 8 0.6 2 0.6 7 0.7 0 0.8 0 0.8 3 0.8 9

1.0 3 0.2 2 1.1 6 1.1 7 1.1 5 1.2 7 1.2 5 1.0 3 0.97 0.8 6 0.5 3 0.9 3 IntO H

(ppt - -rain )



### 91 . 19 . 89 . 119 . 

### 81 . 78 . 71 . 95 . 86 . 128 .
113 . 

### 15 . 112 . 113 - 107 . 126 . 122 . 

### 92 . 121 . 101 . 100 . 106 . Reactiv i t y Resu ]

-Kineti c Reactivity - (Fractio nReacted ) HCH O

0.9 1 0.0 2 0.9 2 0.9 5 0.9 1 0.9 1 0.9 1 0.9 1 0.9 5 0.9 8

0.9 7 0.0 2 0.9 8 0.9 8 0.9 8 0.9 8 0.9 8 0.9 7 0.9 8 0.9 3 0.9 1 0.9 6 Aceton e

0.01 7 0.00 7 0.01 5 0.05 6 0.01 2 0.01 0 0.03 8 0.01 6 0.01 6 0.05 9

0.05 5 0.00 7 0.06 7 0.05 7 0.05 1 0.06 0 0.05 9 0.01 9 0.05 9 0.01 6 0.01 6 0.01 8 Ethene

0.7 1 0.0 6 0.6 9 0.7 8 0.6 9 0.6 5 0.6 3 0.7 1 0.6 9 0.8 2

0.7 6 0.0 1 0.8 3 0.7 6 0.7 5 0.7 9 0.7 8 0.7 0 0.8 0 0.7 2 0.7 3 0.7 1 It s fo r th e Maximum VO C

_—• • Reacti v

Mechanisti c Reactivit y (pp m O ^ / 

### C O

0.9 1 0.0 7 0.8 8 0.8 6 0.8 0 0.8 9 0.8 8 0.9 5 1.0 0 1.0 1

0.9 1 0.1 2 0.8 5 1.0 2 1.0 5 0.9 6 0.9 8 1.0 1 0.8 2 0.8 0 0.7 1 0.8 1 n-C 8

0.22 0.0 6 0.2 0 0.2 9 0.1 5 0.1 9 0.1 5 0.2 5 0.2 6 0.2 9

0.2 7 0.0 7 0.3 1 0.3 1 0.3 1 0.3 2 0.3 1 0.3 1 0.27 0.1 6 0.1 9 0.1 7 ppm C VO

C Toluen e

1.0 5 0.0 9 1.0 7 0.9 1 0.9 1 1.0 2 1.1 3 1.1 0 1.1 6 1.1 0

1.3 0 0.2 5 1.3 0 1.1 5 1.1 5 1.5 1 1.5 3 1.3 8 1.1 2 1.2 3 0.6 8 1.2 8 

### it

y

) Reacted ) Propen e

2.2 5 0.2 3 2.2 5 2.2 6 1.8 1 2.0 5 2.1 5 2.3 9 2.5 0 2.5 2

3.0 1 0.6 3 3.3 3 3.1 2 3.3 6 3.6 7 3.6 1 3.0 5 2.7 8 2.5 1 1.5 8 2.7 1 (con HCH O

1.2 3 0.1 3 1.5 0 3.1 3 3.9 6 1.2 1 1.8 0 1.1 0 1.6 1 1.2 5

1.5 0 0.7 6 1.7 8 1.8 7 1.8 6 5.2 3 5.2 0 1.7 1 1.2 9 1.1 8 2.6 1 1.2 6 tinued )Tabl e 1 . (continued ) - 1 |e j Th e value s lnparenthese s ar e th e percentage s o f the tota l hydrocarbo npresen t a t the en d o f th e simulatio n(assumin g n o chemica l reaction ) whic har e du e t o specie s entraine d fro m aloft . |f ) Thi s scenari o wa s used i nth e aggregate d "bas e case " reactivit y calculations . lg l Thes e scenario s hav e 1 pp m NC " aloft . Alof t N0 Xcontribute s 2 * o f the tota l N O inpu t inth e bas e cas e simulation . |h ) Thi s scenari o ha s 1 pp m N0 Xaloft . Alof t N0 Xcontribute s 5 * o f th e tota l N0 Xinpu t i nth e bas e cas e simulation . (i ) Thes e scenario s hav e 1 pp m N0 Xaloft . Alof t N0 Xcontribute s 5 * o f th e tota l N O inpu t inth e bas e cas e simulation . |J ) Thes e scenario s wer e no t use d fo r derivin g the reactivit y scales , and ar e show nonl y for compariso nwit hpreviou s studie s (Carte r and Atkinson , 1989) . Th e N0 Xinputs , ROG/NO xratios , and maximum ozon e yield s show nar e fo r maximu

m ozon e conditions . |k ] Th e latitud e use d for calculatin g photolysi s rate s wa s arbitraril y chose nt o be tha t o f Lo s Angeles . Otherwise , th e scenario s ar e no t necessaril y designe d t o represen t an y particula r city .

### Tabl e 2 . (continued ) - 2

SeenI D 

### [a ]

Ne w York Avg . S.Dev .
• G-NY 1 • G-NY 2 Philadelp

h Avg . S.Dev . G-PH 1 • G-PH 2 • G-PH 1 • G-PH 5 G-PH 6 G-PH 7 G-PH 8 Phoeni x Avg . S.Dev .
• G-PX 1 • G-PX 2 • G-PX 3 G-PX 1 W-PX 1 G-PX 5 Seattl e Avg . S.Dev . ROG /



### N0 X



### 6. 0 0. 0 6. 0 6. 0 i a 6. 1 0. 8 6. 0 8. 0 7. 0 6. 0 6. 0 6. 0 6. 0
6. 7 0. 5 6. 0 7. 0 7. 0 7. 0 6. 0 7. 0
7. 3 0. 5 Max . 

## ° 3 (ppb )

203 . 

### 1 . 200 . 205 .
177 . 

### 17 . 211 . 250 . 130 . 157 . 116 . 185 . 186 .
123 . 

### 10 . 126 . 126 . 111 . 131 . 112 . 131 .
233 . 

### 32 . Bas e RO

G React' y (O^/ppmC )

0.6 3 0.0 1 0.6 3 0.6 1
0.6 2 0.1 0 0.6 1 0.1 1 0.6 2 0.7 2 0.6 1 0.6 5 0.6 1
0.7 7 0.1 1 1.0 1 0.7 6 0.6 5 0.6 6 0.7 1 0.7 8
0.6 0 0.0 7 IntO

H (ppt - -min )



### 82 . 8 . 77 . 88 . 80 . 12 . 100 . 

### 59 . 79 . 78 . 85 . 79 . 78 . 85 . 21 . 120 . 100 . 

### 72 . 68 . 66 . 88 . 72 . 2 . -Kineti c Reactivity -

(Fractio

nReacted ) HCH O

0.9 7 0.0 0 0.9 7 0.9 7
0.9 5 0.0 3 0.9 6 0.8 9 0.9 5 0.9 6 0.9 7 0.9 5 0.9 1
0.9 1 0.0 3 0.9 8 0.9 5 0.9 2 0.9 1 0.9 2 0.9 6
0.9 3 0.0 2 Acetone

0.01 7 0.00 2 0.01 5 0.01 8
0.01 3 0.00 5 0.01 9 0.03 3 0.01 1 0.01 5 0.01 1 0.01 1 0.01 3
0.01 3 0.00 9 0.05 8 0.01 7 0.03 8 0.03 6 0.03 6 0.01 3
0.03 8 0.00 1 Ethene

0.7 1 0.0 3 0.6 9 0.7 3
0.6 8 0.0 5 0.7 5 0.5 8 0.6 8 0.6 8 0.7 0 0.6 9 0.6 8
0.6 7 0.0 8 0.7 9 0.7 3 0.6 3 0.6 0 0.5 9 0.6 9
0.6 5 0.0 1 _——— Mechanisti c Reactivit y

(pp m 0 , / 

### C O

0.8 2 0.0 6 0.8 6 0.7 8
0.8 3 0.0 6 0.8 1 0.7 0 0.8 3 0.8 8 0.8 6 0.8 1 0.8 6
0.8 6 0.0 1 0.9 0 0.8 0 0.8 6 0.8 7 0.8 8 0.8 1
0.7 3 0.0 1 ppm

C VO C n-C 8 Toluene

0.1 9 0.0 0 0.1 9 0.1 9
0.2 0 0.0 3 0.2 1 0.1 1 0.2 0 0.2 2 0.2 0 0.2 1 0.2 1
0.1 8 0.0 1 0.2 6 0.1 7 0.1 7 0.1 5 0.1 6 0.1 6
0.1 1 0.0 1 0.8 7 0.0 1 0.8 7 0.8 7
0.8 9 0.0 9 0.8 0 0.7 5 0.9 2 1.0 2 0.8 9 0.9 1 0.9 3
1.1 0 0.0 8 1.2 2 1.0 1 1.0 0 1.0 8 1.1 6 1.0 9
0.9 6 0.1 0 « • — ~~_ Reacted ) Propen e

1.8 1 0.0 1 1.8 3 1.8 5
1.8 6 0.2 1 1.8 5 1.3 7 1.8 9 2.1 6 1.8 6 1.9 6 1.9 5
2.2 6 0.3 6 2.9 7 2.1 9 1.9 5 2.0 3 2.1 8 2.2 1
1.8 3 0.2 1 (co n HCHO

1.0 8 0.0 1 1.0 9 1.0 7
3.6 6 0.3 6 3.5 7 2.8 9 3.6 8 3.8 5 3-9 3 3.8 1 3.8 8
1.1 9 0.3 0 5-0 1 1.3 0 1.2 5 1.2 1 1.5 5 1.6 1
3.7 2 0.3 2 tinued )P.7 0

Ci Ci Ci Ci 1 1 1 1 see s 3 > X > 3 > S > j r w f o - *

o > U l U l U l OOO O 0 ) 0 0 c o a - •3 > r C 3 < 3 f D O Q O Q < • c r

O 3 O U l O l VJ 1 

### oocnooocjo n

i i i i i i i i i i HHHHHHHHH H r-r-t-r-r-r-r-r-r-r
- C o



## b < a O Q < • c u

0* » O* * O v U l O v O v O v O v O v O v O U l OOOOOOOOO O W v O

W O O O

OOO O

— 0 C D C D 0 0

ODOOO O

OOO O V O V O V O V O W O v C D 0 3
OOO O 

## b b b b J rj rU l u i WONO\U l
ooo o

- J VD^ J - J

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## b b o X T 0 0 O v

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o o O V O £ U I
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———

rorororur o VO\OvOWWW-0~ J vOvOOO—J00—0-JO v

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3 T J T J r r 1

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- 1 C D O r r r*. o 3 3 3 f D a > o r r f D Q . N _ ^(PP 3 3 r r O

1
— M > 3 to c r >—• O 3 1 f D 0 ) ( 3 r r »-> • < ** • r r * < i

i i i i 3 C f D O o 1 W o 0 0 v . H T J O ^ c f D 3 f D T 3 ~t o T D f D 3 f D X n o T J 3 n < c o o 3 1 f D D J O r r f D CL **•-" 3 " 0 > 3

* * • C A r r

• — ra 3 3 f D C U o r r >—. < i ^

. rr > < I I 1Tabl e 2 . (continued ) - 1

See nI D [a ]

• W-WA 1 • G-UA 5 Chicag o • W-CH 1

St . Loui s • W-SL 1 ROG /

NO x

6. 0 6. 0


### 6. 0

1. 0 Lo s Angele s • H-LA1 6. 0 SanFranc j Avg . S.Dev .
• W-SF 1 • W-SF 2
Al l Abov

e Avg . S.Dev . LSC O

9. 0 1. 1 10. 0 8. 0
Urba n 6. 2 1. 2 Max . 

## ° 3 (ppb )

115 . 108 .
157 .



### 91 . 287 .
193 . 35 . 168 . 217 .
Area s 160 . 61 . Bas e RO

G React' y (O^/ppmC )

0.8 1 0.6 1
0.8 0

0.7 5
0.6 3
0.1 0 0.1 5 0.2 9 0.5 1 [b ] 0.7 1 0.1 5 IntO

H (ppt - -min )

87 . 61 . 

### 93 .
61 . 69 . 51 . 27 . 32 . 70 .

82 . 16 . -Kineti c Reactivity -

(Fractio

nReacted ) HCH O Aceton

e Ethen e

0.9 1 0.9 2
0.9 7

0.9 3
0.9 1
0.8 1 0.1 5 0.7 0 0.9 1

0.9 1 0.0 1 0.01 1 0.03 1
0.01 9

0.01 1
0.03 9
0.02 8 0.01 5 0.01 8 0.03 8

0.01 1 0.00 7 0.6 9

0.5 8
0.7 3

0.5 7
0.6 7
0.5 1 0.1 7 0.3 8 0.6 3

0.6 7 0.0 7 Mechanisti c Reactivit y (pp m O o / ppm C VO C Reacted ) C O n-C 8 Toluene Propen e HCH O

0.9 0 0.8 9
0.8 2

0.9 3
0.7 9
0.7 5 0.0 3 0.7 7 0.7 3

0.8 1 0.0 7 0.1 7 0.1 9
0.1 6

0.2 1
0.1 1
0.1 1 0.0 3 0.1 2 0.1 6

0.1 9 0.0 1 1.1 7 0.9 8
1.0 5

1.1 5
1.0 1
0.8 0 0.0 1 0.7 9 0.8 0

1.0 2 0.1 3 2.3 9

1.9 0
2.2 9

2.1 1
1.9 3
1.1 8 0.2 5 1.3 1 1.6 5

2.1 3 0.3 9 5.2 2 3.9 6
5.0 0

1.5 3
1.1 1
2.9 6 0.1 1 2.8 8 3.0 3

1.2 2 0.5 1

EKM A Scenario s [c ] EKMA- 1 EKMA- 2 EKMA- 3 6. 1

6. 5 6. 1 166 . 126 . 91 . 0.6 1 0.7 5 0.7 6 73 .

119 - 156 . 0.9 1

0.9 7 0.9 8 0.01 1 0.05 6 0.06 8 0.6 5

0.8 0 0.8 7 0.8 1

0.8 0 0.7 6 0.1 9 0.2 1 0.3 1 0.9 1 0.8 5 0.7 6 1.8 7 2.1 2 2.1 2 3.7 5 3.8 3 2.9 8
Notes : [a ] A n"* " indicate s thi s scenari o wa s use d t o calculat e mechanisti c reactivitie s fo r al l VOCs . [b ] Average s o f average s fo r eacho f th

e 1 2 urba

nareas . [c ] No t use

d l nderivin

g th e maximu

m reactivit

y sc 1 0 . Show

nfo r compariso

npurpose s only .Tabl e 3

. Calculate d R0G/N0 xRatio s an d Selecte d Reactivit yResult s fo rth e Maximu m Ozon e Concentratio n Scenarios

. See n I D [a ] ROG /

N0 X

Massachusett s Avg . S.Dev . G-MA 1

• G-MA 2

• G-MA 3 G-MA 1 W-MA 1 G-MA 5 G-MA 6 G-MA 7 Nashvill e Avg . S.Dev .

• G-NA 1 G-NA 2 G-NA 3 G-NA 1 G-NA 5 G-NA 6 G-NA 7
• G-NA 8 W-NA 8 G-NA 9 Ne w Yor k Avg . S.Dev . 7. 1

2. 0 8. 0 5. 0 10. 0 8. 0 10. 0 6. 0 7. 0 5. 0

9. 2 1. 7 8. 0 8. 0 8. 0 10. 0 10. 0 8. 0 8. 0 12. 0 8. 0 12. 0

8. 0 0. 0 Max . 

## ° 3 (ppb )

137 . 19 . 153 . 118 . 151 . 119 . 153 . 113 . 111 . 115 .
101 . 20 . 97 . 101 . 106 . 88 . 93 . 122 . 131 . 85 . 110 . 80 .
239 . 1 . Bas e RO G React' y 

### (OyppmC )

0.2 9 0.0 8 0.2 8 0.3 7 0.1 7 0.3 2 0.1 8 0.3 1 0.2 9 0.3 6

0.1 1 0.0 7 0.5 3 0.1 7 0.1 8 0.1 1 0.1 1 0.1 8 0.1 9 0.3 5 0.2 9 0.1 1

0.2 0 0.0 1 IntO H

(ppt

- -min )

111 . 31 . 130 . 166 . 113 . 116 . 111 . 111 . 179 . 191 .
162 . 23

- 181 . 179 . 177 . 180 . 180 . 168 . 165 . 131 . 120 . 137 .
121 . 11 . -Kin e

(Fr a HCH O

0.9 7 0.0 2 0.9 5 0.9 7 0.9 8 0.9 6 0.9 6 0.9 7 1.0 0 0.9 9

0.9 9 0.0 2 0.9 9 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 0.9 9 0.9 6 0.9 6 0.9 9

0.9 9 0.0 0 ti c Reactivity

ctio n Re z Aceton e

0.06 2 0.01 1 0.05 8 0.07 1 0.05 2 0.05 2 0.05 1 0.06 2 0.07 6 0.07 9
0.07 0 0.01 0 0.07 9 0.07 8 0.07 7 0.07 8 0.07 7 0.07 1 0.07 2 0.05 6 0.05 2 0.05 8

0.06 0 0.00 3 icted )

Ethen e

0.8 3 0.0 6 0.8 0 0.8 6 0.7 8 0.7 8 0.7 6 0.8 3 0.9 0 0.9 2

0.8 6 O.O' I 0.8 9 0.8 9 0.8 9 0.8 9 0.8 9 0.8 8 0.8 8 0.7 9 0.7 8 0.8 2

0.8 3 0.0 2 ——— — Mechanisti c Reactivit y

(pp m0 ^ / C O

0.1 7 0.0 1 0.1 7 0.5 0 0.1 1 0.5 2 0.1 1 0.1 9 0.1 3 0.1 8

0.1 7 0.0 2 0.5 0 0.1 9 0.1 8 0.1 1 0.1 1 0.1 9 0.5 0 0.1 1 0.1 9 0.1 5

0.1 5 0.0 7 n-C 8

0.1 1 0.0 1 0.1 0 0.1 8 0.0 6 0.1 1 0.0 1 0.1 3 0.0 9 0.1 1

0.1 6 0.0 5 0.2 0 0.1 9 0.1 9 0.1 7 0.1 6 0.1 9 0.1 9 0.0 8 0.1 3 0.0 8

0.1 1 0.0 1 ppm C VO C Toluen e

0.2 2 0.0 8 0.2 3 0.2 6 0.0 9 0.3 0 0.0 9 0.2 7 0.1 8 0.3 0

0.3 5 0.0 6 0.1 3 0.3 1 0.3 1 0.3 3 0.3 3 0.3 1 0.3 6 0.3 6 0.2 1 0.1 0

0.0 1 0.0 2 ____

Reacted ) Propen e

0.8 8 0.2 1 0.8 7 1.1 2 0.5 6 0.9 6 0.5 9 1.0 5 0.8 8 1.0 1

1.3 2 0.1 9 1.5 6 1.1 2 1.1 2 1.3 1 1.3 3 1.1 1 1.1 5 1.1 0 0.9 1 1.2 6

0.6 1 0.0 3 HCH O

1.3 6 0.2 1 1.1 7 1.1 1 1.0 1 1.7 6 1.1 8 1.3 2 1.1 2 1.5 6

1.2 1 0.2 1 1.3 8 1.0 6 1.1 6 0.8 6 1.0 0 1.3 6 1.5 1 1.2 1 1.1 5 1.3 6

1.0 7 0.0 7 (continued )Tabl e 3 . (continued ) - 3

SeenI D 

### [a ]

• G-NY 1 • G-NY 2 ROG /



### N0 X



### 8. 0 8. 0 Philadelphi a Avg . S.Dev . G-PH 1 G-PH 2 • G-PH 1 G-PH 5 G-PH 6 • G-PH 7 G-PH 8 Phoeni x Avg . S.Dev .
• G-PX 1 G-PX 2 G-PX 3 • G-PX 1 W-PX 1 G-PX 5 Seattl e Avg . S.Dev .
• G-PG 1 G-PG 2 

### 8. 9

1. 1 8. 0 10. 0 10. 0 10. 0 

### 8. 0 8. 0 8. 0
10. 3 

### 0. 8 10. 0 10. 0 10. 0 12. 0 10. 0 10. 0
10. 0 

### 0. 0 10. 0 10. 0 Max . 

# ° 3 (ppb )

238 . 239 .
215 . 

### 59 . 239 . 310 . 157 . 207 . 131 . 231 . 231 .
152 . 

### 16 . 117 . 111 . 130 . 175 . 162 . 155 .
291 . 

### 27 . 319 . 320 . Bas e RO

G React* y (Og/ppmC )

0.2 1 0.1 9
0.2 1 0.0 1 0.2 5 0.2 1 0.1 7 0.2 1 0.2 6 0.2 7 0.2 7
0.3 1 0.0 5 0.3 7 0.3 1 0.2 9 0.2 1 0.3 2 0.3 1
0.2 1 0.0 3 0.2 0 0.2 0 IntO

H (ppt - -min )

116 . 131 .
121 . 

### 20 . 111 . 

### 81 . 119 . 138 . 119 . 126 . 125 .
125 . 

### 11 . 132 . 110 . 109 . 116 . 125 . 128 .
108 . 

### 10 . 92 . 93 . -Kineti c Reactivity -

(Fractio

nReacted ) HCH O

0.9 9 0.9 9
0.9 8 0.0 1 0.9 8 0.9 5 0.9 9 1.0 0 0.9 9 0.9 9 0.9 9
0.9 8 0.0 1 0.9 6 0.9 8 0.9 7 0.9 8 0.9 8 0.9 9
0.9 8 0.0 2 0.9 5 0.9 6 Aceton

e

0.05 8 0.06 2
0.05 6 0.00 8 0.06 2 0.01 0 0.05 7 0.06 1 0.05 5 0.05 9 0.05 8
0.05 5 0.00 1 0.05 8 0.06 0 0.01 9 0.05 1 0.05 5 0.05 7
0.05 0 0.00 1 0.01 1 0.01 1 Ethene

0.8 2 0.8 5
0.8 1 0.0 5 0.8 1 0.6 9 0.8 1 0.8 5 0.8 1 0.8 3 0.8 2
0.8 0 0.0 3 0.7 9 0.8 3 0.7 6 0.7 7 0.8 0 0.8 2
0.7 8 0.0 3 0.7 3 0.7 3 ~ —~- mm. Mechanisti c Reactivity (pp m 0 ^ / 

### C O

0.5 0 0.1 0
0.1 7 0.0 1 0.1 5 0.1 6 0.1 5 0.1 2 0.5 1 0.1 6 0.1 8
0.1 7 0.0 1 0.5 0 0.1 3 0.5 0 0.1 1 0.1 7 0.1 9 '
0.1 0 0.0 1 0.1 0 0.1 0 ppm

C VO C n-C 8 Toluen

e

0.1 2 0.1 0
0.1 1 0.0 1 0.1 2 0.1 0 0.0 9 0.0 9 0.1 1 0.1 2 0.1 2
0.0 9 0.0 1 0.1 1 0.1 0 0.1 0 0.0 7 0.0 9 

## o.i o
0.0 9 0.0 0 0.0 9 0.0 9 0.0 5 0.0 3
0.1 2 0.0 7 0.0 9 0.2 2 0.0 6 0.0 3 0.1 9 0.1 5 0.1 1
0.2 2 0.0 8 0.3 2 0.2 2 0.2 5 0.0 9 0.2 3 0.2 3
0.1 1 0.0 3 0.1 3 0.1 2 ___ . ) Reacted ) Propene

0.6 3 0.5 8
0.7 3 0.1 0 0.7 8 0.6 9 0.5 3 0.6 9 0.7 8 0.8 3 0.8 1
0.9 1 0.1 1 1.1 2 0.9 3 0.9 0 0.7 1 0.9 8 1.0 3
0.7 6 0.0 8 0.6 1 0.6 1 (con l HCH O

1.1 2 1.0 2
1.1 8 0.2 6 1.2 1 1.3 6 0.7 8 0.8 1 1.3 3 1.3 9 1.3 9
1.1 8 0.2 3 1.7 0 1.1 3 1.5 3 1.0 1 1.5 7 1.5 9
1.2 5 0.0 7 1.1 7 1.1 7 iJnued )P.7 4

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### b b © b b b b b ©

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## 2 ^ 8

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n X *-* T l O n s » o f D r r O 3 f D m rr 3 " f D 3 f D

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3 C O o r r • - • 0 3 3 3 f D C U O r r ( U O L v * /dd) 3 O I L O n 0 3 ^ H T J O T J i— > C f D 3 f D T J 1 O T J f D 3 f D X o X o a o 4 ~ M - 3 rt> r r
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. C O O rr M « < • * • r r « < i i i iTabl e 3 . (continued )

See nI D [a ]

Chicag o • W-CH 1 St . Loui s • W-SL 1 ROG /

N0 X



### 8. 0
8. 0 Lo s Angele s • W-LA 1 8. 0 SanFranc j Avg . S.Dev .
• W-SF 1 • W-SF 2
Al l Abov

e Avg . S.Dev . I SC O

13. 0 1. 2 16. 0 10. 0
Urba n 8. 9 1. 6 Max . 

## ° 3 (ppb )

179 .
165 .
367 . 230 . 11 . 220 . 210 .
Area s 198 . 75 . Bas e RO

G React' y (0 3 /ppmC )

0.2 8
0.3 3
0.2 5
0.2 0 0.0 8 0.1 1 0.2 5
[b ] 0.2 9 0.0 7 IntO

H (ppt - -min )

122 .
177 .
103 . 70 . 27 . 50 . 89 .

128 . 28 . -Kineti c Reactivity -

(Fractio

nReacted ) HCH O Acetone Ethen e

0.9 9
0.9 8
0.9 8
0.8 9 0.0 9 0.8 2 0.9 5

0.9 8 0.0 3 0.05 8
0.07 7
0.05 0
0.03 1 0.01 5 0.02 1 0.01 5

0.05 8 0.01 1 0.8 1

0.8 8
0.8 0
0.6 0 0.1 1 0.5 1 0.7 0

0.8 1 0.0 7 Mechan l

(pp m O o / C O n-C 8

0.1 7
0.3 8
0.1 1
0.1 8 0.0 2 0.1 7 0.1 9

0.1 6 0.0 1 0.0 8
0.1 2
0.0 8
0.0 9 0.0 3 0.0 7 0.1 1

0.1 1 0.0 2 sti c Reactivity ppm C VOC Reacted ) Toluen e Propene HCH O

0.1 6
0.1 6
0.1 1
0.1 7 0.0 0 0.1 7 0.1 8

0.1 8 0.0 8 0.8 8

1.0 2
0.7 7
0.7 2 0.1 9 0.5 9 0.8 5

0.8 8 0.1 9 1.6 2

1.2 7
1.6 1
1.2 1 0.1 0 1.1 7 1.3 1

1.3 5 0.1 8

EKM A Scenario s [c ] EKMAEKMAEKMA

### 1 •2

- 3 1 0 8 7 0 0 0 219 . 111 . 101 . 

### 0

0 0 .2 0 .3 8 .16 112 .

175 . 230 . 

### 0

0 0 .99 .99 .99 0.06 1 0.07 1 0.09 1 0.8 5

0.8 9 0.9 1 0.3 7

0.1 9 0.1 7 0.0 9 0.1 7 0.2 1 

### 0 0 0 .0 1 .26 3 1 0.6 3 1.1 0 1.2 7 0.9 8 1.5 3 1.2 9

Notes : [a ] A n"* " indicate s thi s scenari o wa s used to calculat e mechanisti c reactivitie s for al l VOCs . [b ] Average s o f average s fo r eacho f th

e 1 2 urba

nareas . [c ] No t use

d i nderivin

g th e maximu

m reactivit

y scale . Show

nfo r compariso

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X B J

5 0 

## 8 " 5 D ft B J ra

X B J

BJ 3 Q .

O N 0 3 ftTabl e 1 . (continued ) - 2
Mode l Cod e (a )

21-DM-C 5 3-ME-C 6 1-ME-C 6 BR-C 7 23-DM-C 5 IS0-C 8 1-ME-C 7 BR-C 6 BR-C 9 1-ET-C 7 BR-C1 0 1-PR-C 7 BR-C1 1 BR-C1 2 BR-C1 3 BR-C1 1 BR-C1 5 CYCC 5 HE-CYCC 5 CYC-C 6 CYCC 6 CYC-C 7 HE-CYCC 6 ET-CYCC 6 CYC-C 8 CYC-C 9 CYC-C1 0 CYC-C1 1 CYC-C1 2 CYC-C1 3 CYC-C1 1 CYC-C1 5 VO C Descriptio n

2,1-Dimethy l Pentan e 3-Methy l Hexan e 1-Methy l Hexan e Branche d C 7 Alkane s 2,3-Dlaethy l Pentan e Iso-Octan e 1-Methy l Heptan e Branche d C B Alkane s Branche d C 9 Alkane s IJ-Ethyl Heptan e Branche d CI O Alkane s 31-Propy l Heptan e Branche d C Ualkane s Branche d C1 2 Alkane s Branche d C1 3 Alkane s Branche d C1 1 Alkane s Branche d C1 5 Alkane s Cyclopentan e Methylcyclopentan e C 6 Cycloalkane s Cyclohexan e C 7 Cycloalkane s Methy 1 c y c lohexan e Ethylcyclohexan e C 8 Cycloalkane s C 9 Cycloalkane s CI O Cycloalkane s C1 1 Cycloalkane s C1 2 Cycloalkane s C1 3 Cycloalkane s C1 1 Cycloalkane s C1 5 Cycloalkane s kO H Ib J (pp m ' min"' )

1.0E» 1 1.IE+ 1 1.1E« 1 1.1E* 1 1.1E* 1 6.9E* 3 1.3E« 1 1.3E+ 1 15E« 1 1.5E+ 1 17E+ 1 1.7E. 1 2.1E. 1 2.3E« 1 25E* 1 2.7E« 1 2.9E< 1 8.2E« 3 1.0E» 1 1.2E* 1 1.2E* 1 1.5E*»I 1.5E« 1 1.8E* 1 1.8E+ 1 2.1E* 1 2.3E* 1 2.6E* 1 2.9E* 1 31E» 1 33E* 1 35E» 1 Kineti c

(Tract. . MaxRc t

0.5 6 0.5 8 0.5 8 0.5 8 0.5 B 0.1 3 0.6 1 0.6 1 0.7 2 0.7 2 0.7 6 0.7 6 0.8 2 0.8 5 0.8 7 0.8 9 0.9 1 0.1 9 0.5 7 0.6 1 0.6 1 0.7 1 0.7 1 0.7 7 0.7 7 0.8 1 0.8 5 0.8 8 0.9 1 0.9 2 0.9 3 0.9 1 React .

react ) MaxO j

0.7 2 0.7 1 0.7 1 0.7 1 0.7 1 0.5 9 0.8 0 0.8 0 0.8 6 0.8 6 0.8 9 0.8 9 0.9 3 0.9 5 0.9 6 0.9 7 O.9 8 0.6 5 0.7 1 0.7 9 0.7 9 0.8 5 0.8 5 0.9 0 0.9 0 0.9 3 0.9 5 0.9 6 0.9 8 0.9 8 0.9 9 0.9 9 Mech . React .

(mo l 0,/mo l C ) MaxRc t

0.5 7 0.1 1 0.1 1 0.1 1 0.1 9 0.1 8 0.3 3 0.3 3 0.2 8 0.2 8 0.2 3 0.2 3 0.2 6 0.2 6 0.1 9 0.11 7 0.13 2 0.9 5 0.8 7 0.3 8 0.3 8 0.1 9 0.1 9 0.5 2 0.5 2 0.5 7 0.1 5 0.1 1 0.3 9 0.3 0 0.2 8 0.2 6 MaxO j

0.2 5 0.2 1 0.2 1 0.2 1 0.2 5 0.2 0 0.1 6 0 . 1 6 0 . 13 6 0.13 6 0 . 11 2 0.11 2 0 . 11 2 0 . Il l 0 . 10 8 0.08 7 0.07 8 0.1 5 0.1 3 0.1 8 0.1 8 0.2 3 0.2 3 0.2 5 0.2 5 0.2 8 0.2 3 0.2 1 0.2 0 0.1 6 0.13 8 0.13 1 Incrementa l

(mo l O^ J HaxRc t

0.3 2 0.2 5 0.2 5 0.2 5 0.2 9 0.2 1 0.2 1 0.? 1 072 0 0.2 0 0.1 8 0.1 8 0.2 1 0.2 2 0 . 1 7 0.13 1 0.12 0 0.1 7 0.5 0 0.2 5 0.2 5 0.3 1 0.3 1 0.1 0 0.1 0 0.1 7 0.3 8 0.3 6 0.3 5 0.2 7 0.2 6 0.2 5 'mo l C )

MaxO j

0.1 8 0.1 6 0.1 6 0.1 6 0.1 9 0.11 9 0.12 8 0.12 8 0.11 7 0.11 7 0.10 0 0.10 0 0.13 2 0.13 1 0.10 1 0.08 1 0.07 6 0.2 9 0.3 2 0.11 3 0.11 3 0.2 0 0.2 0 0.2 2 0.2 2 0.2 6 0.2 2 0.2 0 0.2 0 0.1 5 0.13 6 0.13 0 Reactlv i

(g m 0 3 / MaxRc t

1.0 7 0.8 5 0.8 5 0.8 5 0.9 6 0.7 0 0.7 2 0.7 2 0.6 8 0.6 8 0.6 0 0.6 0 0.7 2 0.7 5 0.5 7 0.1 1 0.1 1 1. 6 1. 7 0.8 1 0.8 1 1.1 7 1.1 7 1.3 6 1.3 6 1. 6 1.3 1 1.2 3 1.2 0 0.9 1 0.8 8 0.8 5 t

y D e rlw . g m VOC ) Codelc ) Max0 3 KRMR

0.6 1 0.5 3 0.5 3 0.5 3 0.6 3 0.1 0 0.1 3 0.1 3 0.3 9 0.3 9 0.3 1 0.3 1 0.1 5 0.1 5 0.3 5 0.2 9 0.2 6 1.0 0 1.0 8 0.1 9 1 0.1 9 1 0.6 7 1 0.6 7 1 0.7 6 1 0.7 6 1 0.8 9 1 0.7 1 1 0.7 0 0.6 8 0.5 2 0.1 7 0.1 1 1 2

1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 1 2 1 2 1 2 Unc't y

Cod e Id ]

5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 5 5 5 5 5 1 5 6 6 6 6 6 6 6 6 (continued )Tabl e 1 . (continued ) - 3 Mode l Code [a ]

ETHENE PROPEN E 1-BUTEN E 1-PENTE N 3M-1-BUT 1-HEXEN E C6-0LE 1 C7-0LE 1 C8-0LE 1 C9-0LE 1 C10-OLE 1 C11-OLE 1 C12-OLE 1 C13-OLE 1 C11-OLE 1 C15-OLE 1 1S0BUTE N 2M-1-BUT T-2-BUT E C-2-BUT E 2H-2-BUT C5-OLE 2 23M2-BU T C6-OLE 2 C7-0LE 2 C8-0LE 2 C9-OLE 2 C10-0LE 2 VO

C Descriptio

n

Alkene s Ethen e Propen e 1-Buten e 1-Penten

e 3-Methyl-1-Buten

e 1-Hexen e C 6 Termina l Alkene s C 7 Termina l Alkene s C 8 Termina l Alkene s C 9 Termina l Alkene s CI O Termina l Alkene s C1 1 Termina l Alkene s C1 2 Termina l Alkene s C1 3 Termina l Alkene s C1 1 Termina l Alkene s C1 5 Termina l Alkene s Isobuten

e 2-Methyl-1-Buten

e trans-2-Buten

e cls-2-Buten

e 2-Methyl-2-Buten

e C 5 Interna l Alkene s 2,3-Dlmethy1-2-Buten e C 6 Interna l Alkene s C 7 Interna l Alkene s C 8 Interna l Alkene s C 9 Interna l Alkene s CI O Interna l Alkene s kO H lb ] (PP" " min"' )

1.2E* 1 3.8E« 1 1.6E« 1 1.6E* 1 1.6E* 1 5.1E* 1 51E* 1 5.1E» 1 5.1E+ 1 51E« 1 5.1E* 1 5.1E« 1 5.1E« 1 5.1E* 1 5.1E-. 1 5.1E* 1 7.5E* 1 8.BE+ 1 9.2E+ 1 8.2E* 1 1.3E* 5 9.2E» 1 1.6E* 5 92E* 1 9.2E* 1 9.2E+ 1 9.2E« 1 9.2E* 1 Kineti c

(fract . MaxRc t

0.6 7 0.9 2 0.9 5 0.9 5 0.9 5 0.9 6 0.9 6 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1 .0 0 1 .0 0 1 .0 0 1 .0( 1 1 .0 0 1 .0 0 1 .0 0 1 .0 0 1 .0 0 1 .0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1 .0 0 React .

react ) MaxO ^

0.8 1 0.9 7 0.9 8 0.9 8 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1 .0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 Mech . React .

(mo l 0,/mo l C ) MaxRc t

2. 3 2 . 1 1. 9 1.3 1 1.3 1 0.9 1 0.9 1 0.7 0 0.5 5 0.1 6 0.3 8 0.3 1 0.3 0 0.2 7 0.2 5 0.2 3 1.2 1 1.0 9 2 . 1 2 . 1 1.1 5 1. 8 1.0 7 1. 5 1.2 7 1.0 7 0.9 3 0.8 2 MaxO ^

0.9 5 0.8 5 0.7 2 0.1 9 0.1 9 0.3 1 0.3 1 0.2 6 0.2 0 0 . 1 6 0.13 7 0.11 9 0 . 10 6 0.09 5 0.08 7 0.08 1 0.5 0 0.1 5 0.8 2 0.8 2 0.5 3 0.6 7 0.3 6 0.5 6 0.1 6 0.3 8 0.3 3 0.2 9 Incrementa l

(mo l 0,/mo l C ) MaxRc t

1. 6 1 9 1. 8 1.2 1 1.2 1 0.8 7 0.8 7 0.7 0 0.5 5 0.1 6 0.3 8 0.3 1 0.3 0 0.2 7 0.2 5 0.2 3 1.2 1 1.0 9 2 . 1 . 2. 1 1.1 5 1. 8 1.0 7 1. 5 1.2 7 1.0 7 0.9 3 0.8 2 Max0 3

0.7 7 0.8 3 0.7 0 0.1 8 0.1 9 0.3 1 0.3 1 0.2 6 0.2 0 0.1 6 0.13 7 0.11 9 0.10 6 0.09 5 0.08 7 0.08 1 0.5 0 0.1 5 0.8 2 0.8 2 0.5 3 0.6 7 0.3 6 0.5 6 0.1 6 0.3 8 0.3 3 0.2 9 Reactlv l

(g m O^ / MaxRc t

5. 3 6. 6 6. 1 1. 2 1. 2 3. 0 3. 0 2. 1 1 9 1. 6 13 2 11 5 1.0 3 0.9 3 0.8 6 0.8 0 1. 2 3. 7 7. 3 7. 3 5. 0 6. 2 3. 7 5. 3 1. 1 3. 6 3. 2 2. 8 t

y g m VOC ) MaxO ,

2. 6 2. B 2. 1 1. 6 1. 7 1.1 6 1.1 6 0.8 8 0.6 8 0.5 6 0.1 7 0.1 1 0.3 6 0.3 3 0.3 0 0.2 8 1 7 1. 5 2. 8 2. 8 1. 8 2. 3 1.2 2 1. 9 1. 6 13 0 1.1 3 0.9 9 Derlv .

Code|c )
KRM R

2 1 2 1 2 1 2 1 3 3 2, 1 1 3 3 5 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 1 1 1 1 1 1 3 3 1 1 1 1 1 1 1 1 5 1 5 1 5 1 5 1 Unc't y

Cod e Id ]

1 3 3 5 5 3 5 6 6 6 6 6 6 6 6 6 1 5 1 1 5 5 5 6 6 6 6 6 (continued )Tabl e 1 . (continued ) - 1 Hode l Code 

## M

C11-0LE 2 C12-OLE 2 C13-OLE 2 C11-0LE 2 C15-0LE 2 13-BUTD E ISOPREN E CYC-PNT E CYC-HEXE A-PINEN E B-PINEN E

BENZEN E TOLUEN E C2-BEN Z N-C3-BE N 1-C3-BE N S-C1-BE N C10-BEN 1 C11-BEN 1 C12-BEN 1 M-XYLENE O-XYLEN E P-XYLEN E C9-BEN 2 C10-BEN 2 C11-BEN 2 C12-BEN 2 VO

C Descriptio

n

,
C1 1 Interna l Alkene s C1 2 Interna l Alkene s C1 3 Interna l Alkene s C1 1 Interna l Alkene s C1 5 Interna l Alkene s 1,3-Butadlen

e Isopren e Cyclopenten

e Cyelohexene a-Plnen e b-Plnene Aromati c Hydrocarbon s Benzen e Toluen e Ethyl Benzen

e n-Propyl Benzen

e Isopropyl Benzen

e s-Butyl Benzen

e CI O Honoalky l Benzene s C1 1 Honoalky l Benzene s C1 2 Honoalky l Benzene s m-Xylene o-Xylen e p-Xylen e C 9 Dlalkyl * Benzene s CI O Dlalkyl Benzene s C1 1 Dlalkyl Benzene s C1 2 Dlalkyl Benzene s kO H [b ] (pp m min' 1 )

9.2E« 1 9.2E+ 1 9.2E+ 1 9.2E« 1 9.2E4 1 9.7E+ 1 1.5E* 5 97E* 1 9.8E4 I 7.8E* 1 1.1E« 5

19E* 3 8.7E« 3 1.0E« 1 8.8E4 3 95E* 3 8.BE. 3 8.7E* 3 8.7E« 3 8.7E* 3 35E* 1 2.0E4 1 2.1E+ 1 35E» 1 35E» 1 3.5E* 1 35E* 1 Kineti c

(fract . MaxRc t

1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1 .0 0 1.0 0 1.0 0 1.0 0 1.0 0

0.11 3 0.5 1 0.5 7 0.5 1 0.5 1 0.5 1 0.5 1 0.5 1 0.5 1 0.9 1 0.8 1 0.8 2 0.9 1 0.9 1 0.9 1 0.9 1 React .

react ) Max0 3

1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0 1.0 0

0.2 1 0.6 7 0.7 1 0.6 8 0.7 1 0.6 8 0.6 7 0.6 7 0.6 7 0.9 9 0.9 2 0.9 3 0.9 9 0.9 9 0.9 9 0.9 9 Hech .

(mo l 0 MaxRc t

0.7 3 0.6 7 0.6 1 0.5 7 0.5 3 2. 2 1. 8 1.1 3 0.9 1 0.5 5 0.5 5

0.5 1 1.0 0 0.8 8 0.7 8 0.7 8 0.7 0 0.7 0 0.6 1 0.5 8 1. 8 1. 8 1. 8 1. 6 1.1 1 1.2 8 1.1 8 React. . j/mo l C ) Max0 3

0.2 6 0.2 1 0.2 2 0.2 0 0.1 9 0.8 5 0.7 0 0.1 0 0.3 6 0.2 1 0.2 1

0 . Il l 0.1 7 0.11 5 0.12 9 0.12 9 0.11 6 0.11 6 0.10 6 0.09 7 0.5 2 0.5 2 0.5 2 0.1 6 0.1 2 0.3 8 0.3 5 l

n (mo l O j
MaxRc t

0.7 3 0.6 7 0.6 1 0.5 7 0.5 3 2. 2 1. 8 1.1 3 0.9 1 0.5 5 0.5 5

0.07 7 0.5 1 0.5 0 0.1 0 0.1 2 0.3 6 0.3 6 0.3 2 0.3 0 1 7 1.1 2 1.1 5 1.1 8 13 3 1.2 1 1.1 1 crementa l /mo l C ) MaxO ?

0.2 6 0.2 1 0.2 2 0.2 0 0.1 9 0.8 5 0.7 0 0.1 0 03 6 0.2 1 0.2 1

0.02 1 0.11 1 0.10 7 0.08 7 0.09 1 0.07 8 0.07 8 0.07 1 0.06 5 0.5 1 0.1 8 0.1 8 0.1 6 0.1 1 0.3 7 0.3 1 Reactlv l

(g m Oj /
MaxRc t

2. 5 2 3 2. 1 1 9 1. 8 7. 7 6. 5 1. 0 3 3 1. 9 1. 9

0.2 8 1. 9 1. 8 1.1 1 1. 5 1.2 9 1.2 8 1.1 6 1.0 6 6. 0 5. 2 5. 2 5. 3 1. 8 1. 3 3. 9 t

y g m VOC ) MaxO j

0.8 9 0.8 1 0.7 1 0.6 9 0.6 1 3- 0 2. 5 1.1 1 1.2 7 0.7 1 0.7 1

0.08 8 0.1 1 0.3 9 0.3 1 0.3 3 0.2 8 0.2 8 0.2 5 0.2 3 1 9 1. 7 1. 8 1. 6 1.1 7 13 3 1.2 2 Derl v

Code ] K R

5 5 5 5 5 1 1 1 1 5 5

1 _ c ] M R

1 1 1 1 1 1 1 1 1 1 3

1 1 3 3 3 3 3 3 3 l 3 3 3 3 3 3 Unc't y Cod e Id ]

6 6 6 6 6 6 1 6 6 1 6

3 3 5 5 5 5 6 6 6 3 3 5 6 6 6 6 (continued )Tabl e 1 . (continued ) - 5
Mode l VO C Descriptio n Cod e la ] kO H l M
- 1 (PP * min"' ) Kineti c React .

(Tract , react ) MaxHc t MaxO n Mech . React , (mo l Oj/mo l C ) MaxRc t MaxO- , Incrementa l Reactivit y Derlv . Unc't y (mo l Oj/mo l C ) (g m O^/g m VOC ) Code|c ) Cod e

_ | d ) MaxRc t MaxO- , MaxRc t MaxO- , K RMR

135-TM B 1,3.5-Trimethy l Benzen e 8.IE4 I 1.0 0 123-TM B 1,2.3-Trimethy l Benzen e I.8E4 I 0.9 8 121-TM B 1,2,1-Trlmethy l Benzen e I.8E4 I 0.9 8 C10-BEN 3 CI O Trialky l Benzene s 8.1E+ 1 C11-BEN 3 C1 1 Trialky l Benzene s 8.IE4 I C12-BEN 3 C1 2 Trialky l Benzene s 8.1E« 1 TETRALI N

Tetrall n5.OE4 I O.9 8 NAPHTHA L Naphthalen e 32E* 1 0.9 3 ME-NAP H Methy l Naphthalene s 7.6E4 I 1.0 0 23-DM N 2,3-Dlmethy l Naphthalen e I.IE4 5 1.0 0 .0 0 .0 0 .0 0 1 .0 0 1.0 0 1.0 0 1.0 0 1.0 0 1 .0 0 1.0 0 0.9 8 1.0 0 1.0 0 2 . 1

2. 1 2 . 1 1. 9 1. 7 1. 6 0.2 0 0.2 5 0.6 1 1.0 1 0.6 7

0.6 7 0.6 7 0.6 0 0.5 1 0.5 0 03 0 012 0 11 5 0.2 7 2. 1

2. 1 2. 0 1. 9 1. 7 1. 6 0.20 . 0.23 ' 0.6 3 1.0 1 0.6 7

0.6 6 0.6 6 0.6 0 0.5 1 0.5 0 0.03 0 0.011 8 0.11 5 0.2 7 7. 5

7. 1 7. 1 6. 7

0.7 3 0.8 7 2. 1

2. 1 2. 1 2. 1 1. 9 1. 8 0.10 9 0.01 1 0.5 1 1.0 0 Acetylen e ACETYLE N

Acetylen e Alcohol s 1 . 1E. 3 0.09 0 0.13 7 1.1 1 0.5 3 0.09 9 0.07 3 0.3 7 0.2 7

MEO H ETO H N-C3-0 H I-C3-0 H 1-C1-0 H N-C1-0 H T-C1-0 H ET-CLYC L PR-GLYC L

FORMAL D ACETAL D PROPAL D Methano l

Ethano l n-Propy l Alcoho l Isopropy l Alcoho l Isobuty l Alcoho l n-Buty l Alcoho l t-Buty l Alcoho l Ethylen e Glyco l Propylen e Glyco l Aldehyde s Formaldehyd e Acetaldehyd e Propionaldehyd e 1.1E 4 3 1.8E4 3 7.8E4 3 7.6E4 3 1.1E4 1 1.2E« 1 1.7E* 3 1.1E+ 1 1.8E* 1

1.1E» 1 2.3E* 1 2.9E> 1 0 . 10 7

0.3 3 0.1 7 0.1 7 0.6 8 0.6 3 0 . 12 7 0.6 0 0.7 6

0.9 1 0.8 3 0.9 1 0 . 1 6

0.1 6 0.6 3 0.6 2 0.8 3 0.7 9 0.1 9 0.7 6 0.9 0

0.9 8 0.9 2 0.9 5 2. 5

1.0 1 1 . 1 7 0.3 3 0.1 1 1.0 0 0.8 9 1.2 1 0.6 3

1. 2 2 . 1 2. 0 0.9 3

0.3 C 0.1 0 0.1 7 0 . 1 9 0.3 7 0.1 0 0.1 8 0.2 5

1.3 0 0.7 7 0.7 0 0.2 7

0.3 1 0.5 5 0 . 1 6 0.2 8 0.6 3 0.11 3 0.7 3 0.1 8

3- 9 1 7 1. 8 0 . 15 0

0 . 1 7 0.2 5 0 . 10 5 0 . 1 6 0.2 9 0.07 7 0.3 7 0.2 3

1.2 6 0.7 0 0.6 6 0.1 0

0.7 0 1.3 3 0 3 7 0.7 2 1. 6 0.2 9 1 1 3 0.9 2

6. 2 3 8 1. 6 0.2 2

0.3 1 0.6 0 0.2 5 0.1 1 0.7 5 0.2 0 0.5 7 0.1 3

2. 0 1. 5 1. 6 2

2 2 1 1 2 2 2 2 2 2 2

1 1 1 (co i 1 2 5 5 5 5 5 5 5

1 3 1 11nued )o o

Tabl e 1 . (continued ) - 6

Hode l Cod e (a ) VOC Descriptio n ? kO H lb ] (ppm ' Kineti c React .

(Tract , react ) Mech . React ,

(mo l Oj/mo l C ) Incrementa l Reactivit y

(mo l Oj/mo l C ) (g

m Oj/g m VOC ) min"' ) MaxRc t MaxO , MaxRc t MaxO; , MaxRc t MaxO- , MaxRc t MaxO- , Deriv . Unc't y Code(c ) Cod e

|d ] K RM R

ACETON E ME K Ketone s

Aceton e C l Ketone s 3.1E* 2 1.7E* 3 0.01 1

0 . 1 6 0.05 8

0.2 2 3. 6

1. 8 0.9 5

0.5 3 0.1 6

0.2 9 0.05 5

0.11 7 0.3 9

0.7 6 0.13 7

0.3 1 Aromati c Oxygenate s BENZAL D Benzaldehyd e 1.9E+ 1 0.8 1 0.9 5 -0.2 0 -0.3 1 -0.1 7 -0.3 0 -0.5 1 -0.9 3 2 1 1 PHENO L Pheno l 39E* 1 1.0 0 1.0 0 0.2 6 -0.1 7 0.2 6 -0.1 7 0.7 9 -0.5 1 1 1 5 CRESO L Cresol s 6.2E+ 1 1.0 0 1.0 0 0.5 1 -0.2 3 0.5 1 -0.2 3 1. 6 -0.7 2 1 1 1 Note s a . Detale dmode l specie s nam e use di

nthe mechanis m

(Carter , 1990) . to. Hydroxy l radica l rat e constan t Tor T=30 0 Kusedi nthe mechanis m

(Carter , 1990) . c . Code s for derivatio no f reactivitie s ar e a s follows : Kineti c Reactivitie s (KR) : 1 . Kineti c reactivit y estimate dusin g Equatio n(VI) , an dIntO H = 8 2 ppt-mi nTo r maximu m reactivit y

or IntO

H = 12 8 ppi-mi nIo

i maximu m ozon e conditions . ( \% 2. Kineti c reactivit y calculate dexplicitl y To r al l scenarios , an

d averag e o f average s Tor the 1 2 urba na^ea s used . 3 . Kineti c reactivit y assumed.t o b e th e sam e a s for compoundlistedabove . 1 . Kineti c reactivit y wa s calculate dt o b e greate dthan0.98 . Compoun dassumedt o be essentiall y completel y

reacted . 5 . C7 * alkene s ar e assume dt o b e completel y

reacted . r

l

. Mechanisti c Reactivitie s (MR) : 1 . Mechanisti c reactivit y calculate ddirectl y

Tor selecte dscenarios , an d averag e o f average s for the 1 2 urbanarea s used . 2 . Mechanisti c calculate dfor "pur e mechanism " specie s use dt o estimat e the mechanisti c reactivit y a s describe d b y Carte r and Atkinso n(1989) . Mechanisti c reactivitie s fo r th e "pur e mechanism " specie s reacting wit hO H radica l constant s o r 3.0E+ 3 an d 3-0E+ 1 ppm" 1 min " calculate da s Indicate dabov e lnnot e "d" . Th e value s To r the O H rad l constan t o f thi s specie s estimate db y linea r Interpolatio nI T the rat e constan t i s betwee n3.0E+ 3 an d 3.0E-. 1 ppm * 3 . Per-molecul e mechanisti c reactivit y l s assume dt o b e the sam e a s th e Bbov e compound . 1 . Per-molecul e mechanisti c reactivit y l s assume dt o b e th e averag e o f the compoun dlistedabov e an

d tha t liste dbe i rat e

ca l rat e 1 min"' .Tabl e 5 .

VO C ID [a ]



### C O HETHAN E ETHAN E PROPAN E N-C l N-C 6 N-C 8 ISO-C 8 N-C12 . BR-C1 2 N-C1 5 ETHENE PROPEN E T-2-BUT E ISOBUTE N 1-HEXEN E C10-OLE 1 i C10-OLE 2 BENZEN E TOLUENE H-XYLEN E 135-TM B TETRALI N NAPHTHA L 23-DM N Ratio s o f Reactivitie s o f Selected VOC s Relativ e to th

e Reactl v ROG Surrogate , Derive d fro m Maximu m Ozon e React !

MaxRc t

0.01 7 0.00*1 3 0.06 2 

## o.n o 0.2 7 0.2 6 0.1 7 0.3 0 0.08 1 0.3 2 0.06 1 

### 2. 3 2. 8 3. 1 1. 8 1.2 7 0.5 6 1.1 8 0.12 0 0.7 9 

### 2. 5 3. 2 0.3 1 0.3 7 

### 1. 6 Max0 3

0.03 6 0.007 9 0.10 1 0.2 1 0.1 5 0.1 7 0.3 0 0.1 3 0.11 0 0.1 8 0.10 7 

### 2. 8 3. 0 3. 0 1. 8 1.2 3 0.5 0 1.0 6 0.09 3 0.1 3 

### 2. 0 2. 5 0.11 6 0.01 7 1.0 6 th e Aggregate

d Bas e Case , cit y Scales .

- Reactivity

Relativ

e t o Bas e Cas e Ozon

e Yi Avg .
0.01 1 0.008 7 0.11 5 0.2 6 0.1 7 0.1 5 0.1 9 0.3 7 0.02 5 0.1 9 0.006 3 

### 3. 2 3. 5 3. 3 2. 1 1.1 5 0.3 2 1.0 0 0.09 0 0.2 3 

### 1. 9 2. 6 -0.001 5 -0.1 6 0.9 3 Rati o Lin e
(61% ) [b ] 0.02 3 (51* ) (19* ) (17* ) (11* ) (15* ) (0.26 ) (29* ) (0.35 ) (11* ) (0.33 ) (37* ) (25* ) (18* ) (56* ) (12* ) (0.59 ) (52J ) (61* ) (0.69 ) (12* ) (30* ) (0.57 ) (0.77 ) (0.87 ) 0.005 5

0.07 7 0.1 7 0.3 2 0.3 1 0.1 8 0.3 1 0.09 7 0.3 8 0.07 8 

### 2. 5 3. 1 3. 3 1. 9 1.3 2 0.5 1 1.2 2 0.11 1 0.6 5 

### 2. 1 3. 1 0.2 3 0.2 1 1.1 8 3ase Cas e el d 

### Fi t
(11* ) ( 9* ) (10* ) ( 8* ) ( 8* ) ( 8* ) ( 8* ) ( 5* ) (13* ) ( 6* ) (15* ) ( 1* ) ( 2* ) ( 1* ) ( 3* ) ( 2* ) ( 5* ) ( 3* ) ( 5* ) ( 9* ) ( 3* ) ( 1* ) (15* ) (22* ) ( 6* ) it y o f th e Bas e Cas e th e Maximu

m React j

RO G Mixt B Avg .
0.02 7 0.005 8 0.07 2 0.1 7 0.3 0 0.3 1 0.12 6 0.2 6 -0.003 1 0.3 5 -0.02 5 

### 2. 6 3. 2 1. 0 2. 6 0.9 8 0.2 0 1.1 3 0.09 9 0.5 1 

### 2. 3 3. 6 0.2 3 0.11 0 1.3 5 as e Cas e Ratio n
(19* ) (10* ) (33* ) (35* ) (29* ) (35* ) (77* ) (16* ) (0.16 ) (27* ) (0.16 ) (26* ) (16* ) (21* ) (39* ) (15* ) (0.18 ) (21* ) (19* ) (51* ) (17* ) (11* ) , (73* ) (0.27 ) (39* ) Lvity , an

d 

### th e

Ozone Dos e Lin e
0.02 0 0.001 5 0.05 8 0.13 7 0.2 5 0.2 5 0.11 7 0.2 5 0.06 5 0.3 2 0.01 6 

### 2. 3 2. 9 3. 6 2. 2 1.2 0 0.1 1 1.2 5 0.10 2 0.6 8 

### 2. 6 3. 6 0.3 0 0.3 0 

### 1. 6 Fi t

( 6* ) ( 1* ) ( 1* ) ( 1* ) ( 1* ) ( 1* ) ( 6* ) ( 2* ) (15* ) ( 3* ) (21* ) ( 2* ) ( 1* ) ( 2* ) ( 2* ) ( 2* ) ( 6* ) ( 3* ) ( 1* ) ( 3* ) ( 1* ) ( 2* ) ( 5* ) ( 8* ) ( 2* ) (continued )Tabl e 1 . (continued ) d . Mechanisti c uncertaint y codes : (Se e discussio n l n text. ) 1 . Leas t uncertai nmechanism , and teste d usin g environmenta l chambe r data . 2 . Mechanism

probably

no t uncertain , bu t n o chambe r dat a avalabl e t o tes t it
. 3 . Uncertai naspect s o f mechanis madjuste d o r parameterize d t o fi t environmenta l chambe r data . 1 . Mechanism

uncertain , an

d onl ylimite d o r uncertai n chambe r dat a availabl e t o tes t it , o r mechanis mno t optimize d t o fi t existin g chamber data . 5 . Mechanism

estimated , an

d n o chambe r dat a availabl e t o tes t it
. 6 . Mechanism

highly uncertain , an

d n o chambe r dat a availabl e t o tes t It .P.8 4

FIGUR E CAPTION S

Figur e 1 . Plot s o f Mechanisti c Reactivitie s fo r th e Mode l Specie s fo r

Maximu mOzon e Condition s Agains t Mechanisti c Reactivitie s fo r Maximu mReactivit yConditions
. (Th e line s sho wleas t square s fits , force d throug h zero , t o th e result s fo r th e alkane s o r th e aromatics)
.
Figur e 2 . Plot s o f Incrementa l Reactivitie s fo r th e Mode l Specie s fo r

Maximu mOzon e Condition s Agains t Incrementa l Reactivitie s fo r Maximu mReactivit yConditions
. (Th e lin e show s th e relativ e reactivit yo f th e bas e cas e RO G mixture)
.
Figur e 3 . Plot s o f Incrementa l Reactivitie s fo r th e Mode l Species ,

Calculate d usin g Kineti c Reactivitie s fo r Maximu mOzon e Condition s an d Mechanisti c Reactivitie s fo r Maximu mReactivit y Conditions , Agains t Incrementa l Reactivitie s fo r Maximu m Reactivit yConditions
. (Th e lin e show s th e relativ e reactivit y
o f th e bas e cas e RO G surrogate) .
Figur e 4 . Distributio n Plot s o f IntO H an d Mechanisti c Reactivitie s fo r

Selecte d Specie s fo r Representativ e Maximu m Reactivity , Maximu m Ozone , an

d Bas e Cas e N0 XScenarios
.Tabl e 5 . (continued ) - 2
VO C I D [a ]

ACETYLE N MEO H ETO H N-C1-O H FORMAL D ACETAL D ACETONE 

### MEK CRESO L BENZAL D MaxRc t

0.1 6 0.1 7 0.3 0 0.6 9 

### 2. 6 1. 6 0.1 7 0.3 2 0.6 7 -0.2 3 Max0 3

0.2 9 0.2 1 0.3 7 0.8 0 

### 2. 1 1. 6 0.11 6 0.3 3 -0.7 7 -1.0 0 —Reactivit yRelativ e t o

Bas e Cas e Ozon e Y i Avg .
0.3 2 0.2 5 0.3 7 0.7 3 

### 2. 5 1. 8 0.11 7 0.3 4 -3. 0 -2. 0 Rati o Lin e

(57* ) 0.1 9 (38* ) 0.1 9 (11* ) 0.3 2 (27* ) 0.6 8 

### (lot ) 2. 6 (68* ) 1. 7 (16* ) 0.1 6 (33* ) 0.3 3 (5.9 ) 0.08 2 (2.5 ) -0.6 3 Bas e Cas e

el d 

### Fi t
( 9%) ( 5* ) ( 7* ) ( 5* ) ( 5* ) 

### ( 1* ) ( 2* ) 

### ( 1* ) (0.30 ) (26* ) RfinM l vf-nr o

Bas e Cas e Avg . 0.2 1 0.1 8 0.2 4 0.5 4 

### 3. 6 1.2 7 0.13 3 0.2 5 -1.1 0 -1.2 8 Rati o

(12* ) (21* ) (32* ) (18% ) (22%) (58* ) (16* ) (29* ) (3.2 ) (1-30 ) Ozon e Dos e

Lin e
0 . 1 6 0.1 6 0.2 1 0.5 6 

### 3. 4 1.4 7 0.1 5 0.2 8 0.3 7 -0.5 3 

### Fi t

( 5* ) ( 3* ) ( 4* ) ( 2* ) ( 2* ) 

### ( 3* ) ( 2* ) ( 2* ) (35* ) (14* ) [a ] Detaile d mode l specie s nam e use d i n the mechanism
. Se e Tabl e 4 fo r VOC s represente d b y thi s mode l species
. [b ] Quantitie s i n parenthe s ar e standar d deviation s o f aggregate d average s o r lin e fi t slopes . Thes e ar e give n a s percentag e unles s standar d deviatio n i s greate r than 90 * o f the averag e o r th e slope .-1— » > -*- » 

### o D < D 

### C t o -*- > 

### tn 

### c o o Q ) ^ 

### r o O X 

## a X ) < D -4- » O 

### o O J 

### (Y. 

# o O > 

### Oppm

^ ^ 

# o E Q

_ Q

_ 

### z.u -

1.5 -

1.0 -

0.5 -

0.0 -

S

. v j 

### o

D A A V X 

### o

- 9

• 

### Alkane s Alkene s Aromatic s Acetylen e y Aldehyde s s^ Ketone s ^y Alcohol s y^ Aromati cAldehyde s yy ° C O / " v^- ^ 

# I .v^ D 

# < ^ ^

1 T | IIIIII I 

### / Alkane s

V 

### ^Aromatic s

i l l l 

## - . 5 0. 0 0. 5 1. 0 1. 5 2. 0 2. 5 3. 0 3. 5 4. 0 4. 5 5. 0



# MaxRc t Mechanisti cReactivit y (pp m O 3 /

ppm C VO C Reacted )

Figur e 1 . Plot s o f Mechanisti c Reactivitie s fo r th e Mode l Specie s fo r Maximu

m Ozone Condition s Agains t Mechanisti c Reactivitie s fo r Maximu

m Reactivit

y Conditions . (Th

e line s sho

w leas t square s fits , force d throug

hzero , t o th

e result s fo

r th e alkie s or th

e aromatics) .
0 0P.8 7

Figur e 5 . Plot s o f Reactivitie s o f Selecte dVOC s agains t the Reactivit y

o f th e Bas e Cas e RO GSurrogat e Calculate dfo r th e Bas e Cas e N 0 XScenarios .

* = Reactivitie s fo r a city-da y scenario . = Slop e i s maximu

m reactivit y

ratio .

- — = Slop e i s maximu m ozon e reactivit y

ratio .

- - - - = Leas t square s fit , force dthroug hzero .

= Slop e i s averag e o f ratios .
Figur e 6 . Plot s o f Relativ e Bas e Cas e Ozon e Yiel dReactivitie s Agains t

Maximum Reactivitie s andMaximu m Ozon e Reactivitie s fo r Al l th e Mode l Species . (Bas e cas e reactivitie s aggregate dusin g bot hlin e fi t an

daverag e rati o methods. )

Figur e 7 . Plot s o f Relativ e Bas e Cas e Ozon e Dos e Reactivitie s Agains t

Maximum Reactivitie s an

dMaximu

m Ozon e Reactivitie s fo r Al l th e Mode l Species . (Bas e cas e reactivitie s aggregate dusin g bot hlin e fi t an

daverag e rati o methods . Th e line s sho w th e leas t square s fits , force dthroug hzero , t o the Data) .
Figur e 8 . Plot s o f O H Radica l Rat e Constant s (Pe r Mas s Basis ) Agains t

Reactivitie s inth e Maximu m Reactivit y

Scale . (Th e lin e shows th e averag e kOH/maximu m reactivit y

rati o fo r th e bas e cas e RO G surrogate) .

## or :

o 

## ct : X 

# o
QC *: 

## r o O x 

# o u o > 

# E c n

r o O 

# E 14- , 12 - o o

-
o V X • Alkane s X 5 Alkene s Aromatic s Acetylen e X 1 0 Alcohol s X 5 Aldehyde s Ketone s X 5 Aromati c Oxygenate s C O X 10 0



# r 7 0 1 2 3 4 5 

## 6/ 8 

# MaxRc t Reactivit y(g m O 3 / g m VOC ) 1



## 9

Figur e 3 . Plot s o f Incrementa l Reactivitie s fo r th e Mode l Species , Calculate d usin g Kineti c Reactivitie s fo r Maximu

m Ozone Condition s an d Mechanisti c Reactivitie s fo r Maximu

m Reactivity

Conditions , Agains t Incrementa l Reactivitie s fo r Maximu

m R' ' tivit

y Conditions . (Th

e line shows th

e relativ

e
o o o oCJ > 

# o > 

# E c n

r o O 

# E c n

-4->ctiv


## o C D QZ 

## r o O X o ^ 

### 6 

# 1 5 - 4 - 3 - 2 - 1 - 0 - 

# -1- 1 o

D A A O V x • ©

¥ 

## 1 Alkane s X 5 Alkene s Aromatic s Acetylen e X 1 0 Alcohol s X 5 Aldehyde s Ketone s X 5 Aromati c Oxygenate s C O X 10 0

o I 9 ° o . I -p ° ^0 ^ 

### i <^blr<cr cri 

### r " A 1 J«#£A V * y&<z±± i 1 • J 1 1 1 

## 0 1 2 og

° o

i 

## 3 e a s



## . °° o • O o 

# X °°° A °rmy*ZV
A

1 

## 4 o o

a

• A V A

1 

## 5 o° °

A A V

1 

## 6 o °
a ^ 6

A

1 

## 7 o

O ;
O

'
1 

## 8 o

1 

## 9 

# MaxRc t Reactivit y(g m O 3 / g m VOC )

Figur e 2 . Plot s o f Incrementa l Reactivitie s fo r th e Mode l Specie s fo

r Maximu

m Ozone Condition s Agains t Incrementa l Reactivitie s fo r Maximu

m Reactivit

y Conditions . (Th

e lin e show s th e relativ

e reactivit y

o f th e bas e cas e RO

G mixture) .P.9 0

( J O > 

## Ozon e Yiel

d Reactivity n-Octan e 

## Ozon e Dos e Reactivit y

-rt 0.00 0 C J 

### o a > o r Methano l

Toluen e
0.030 -
0.010 -
-.01 0 i—'— i

0.0 0 0.0T0.0 2 0.0 3 0.0 4 O.O S 0. 0 0. 2 0. 4 0. 6 0. 8 

### (g m O 3 / g m VOC

) (ppm-mi n O 3 / g m VOC

) Bas e RO G Reactivit y 

## Figur e 5 . Plot s o f Reactivitie s o f Selecte dVOC s agains t th e Reactivit y

o f th e Bas e Cas e RO

GSurrogat e Calculate dfo r th e Bas e Cas e NO Scenarios . * = Reactivitie s fo r a city-day scenario . • = Slop e i s maximu m reactivit y ratio . — — = Slop e i s maximu

m ozon e reactivit y

ratio . = Leas t square s fit , force dthroug hzer o = Slop e i s averag e o f ratios .P.9 1



### 190- . Ma xReactivit yMa xO 3 Bas e Cas e IntO H Paramete r

Mechanisti c Reactivit yo f n-Octan e

-.0 6 6 4 8 1 2 1 6 0 4 8 1216. 0 4 I I Z 1 6


### Mechanisti c Reactivit y o f Toluen e

Mechanisti c Reactivit yof Formaldehyd e

0 4 8 1 2 1 6 0 4 8 1 2 1 6 0 4 8 1 2 1 6



### Numbe ro f City—Day

s 

### Figur e 4 . Distributio n Plot s o f IntO H an d Mechanisti c Reactivitie s fo r Selecte d Specie s fo rRepresentativ e Maximu m Reactivity , Maximu

m Ozone, an

d Bas e Cas e N0 X 

### Scenarios .0 1



### u o « > UL « V I 

### o Q V


### . 2

•+- < o » 

## a: u o o » n o m

MaxRc t Reactivit y (gm O 3 / g m

VOC ) Max0 3 Reactivit y (gm O 3 / g m

VOC )
Figur e 7 . Plot s o f Relative Bas e Cas e Ozon e Dos e Reactivitie s Agains t Maximu m Reactivitie s an

d Maximu

m Ozone Reactivitie s fo r Al l th

e Mode l Species . (Bas e cas e reactivitie s aggregated usin g bot hline fi t an d averag e rati o methods . Th e line s sho

w th e leas t square s fits , forced throug hzero , t oBas e Case Relative Reactivitie s P.9 3

(Averag e Ratio ) (Un e Rt )



### o» J 0» J

# o



# E E

I c 

# E I 

# E Q . Q
_ 

## X O 250 0 - ,

200 0

1500- J

1000- J

50 0 H o

D A A O 

### V 

# z • Alkane s X 5 Alkene s Aromatic s Acetylen e X 1 0 Alcohol s X 5 Aldehyde s Ketone s X 5 Aromati c Oxygenate s C O X 10 0 a



### ••

D 

### o o a

>o<> T a



### o o o o 

# V

0 1 2 

# MaxRc t Reactivit y(g m O 3 / g m VOC )