UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                      Office of  Air  Quality Planning and Standards
                      Research Triangle  Park, North Carolina 27711
   DATE: NOV 8  1379
SUBJECT: pa t a Assumptions  and- Methodology-. for Assessing the Air Quality Impact of
        Proposed HDV Emission Standards
   FROM: Warren p_  Freas
        Air Management Technology  Branch/MDAD   (MD-14)

     IC; John Anderson
        Emission Control  Technology  Division/OMSAPC

             The attached report describes  the  assumptions and methodology for
        the input data provided  by this office  for the air quality impact analysis
        of proposed HDV  emission standards.  The mobile source emission factors
        calculated by OMSAPC.are not discussed.

             There are several differences  between the current data base and  the
        data base used in the original  (August  1978) HDV air quality impact
        analysis.   The changes reflect  either data updates or new methodologies
        developed during the regulatory reviews of the ambient ozone and carbon
        monoxide standards.   For ozone, the major differences are the use of  a
        VOC rather than  an HC emission  inventory for base year 1976, and new-
        estimates of stationary  source  growth rates and control efficiencies.
        Differences for  carbon monoxide include 1976 base year emission inven-
        tories and air quality design values estimated on a county, rather than
        an AQCR, basis.

             As noted in the original analysis, there is much uncertainty in
        projecting air quality levels for future years.  For this reason, the
        results of the air quality analyses are more appropriate for comparing
        the Relative impact (rather  than the absolute impact) of the various
        control scenarios.

             It was my understanding, from  our  telephone conversation, that you
        planned to adjust the base year inventory to reflect revised estimates
        of HDV emission  factors.  Since this data base will continue to be used
        for future analyses, we  would like  to receive a copy of the correction
        factors, by pollutant, that  were used to perform this adjustment.  Are
        there any plans  to issue corrections to MOB I LEI in the near future?

             If you have any questions  concerning the input data used in this
        analysis., please call me at  FTS 629-5488.
        Attachment
             Charles Gray,
             Mark Wolcott,
ECTD/OMSAPC
ECTD/OMSAPC
             Ed Li 11 is, AMTB/MDAD
             Bruce Jordan, OAQPS

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    DATA ASSUMPTIONS AND METHODOLOGY FOH  •

 SSI1SS.TKG THE AIR QilALITY IMPACT OF S-'ROi-OSh'D

 EMISSION STANDARDS FOR HEAVY-DUTY VEHICLES
      Air Management Techno]ooy Branch
    Monitoring ami Data Analysis Division
Office of Air'Quality Planning and Standard:
                November 1979

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                    DATA ASSUMPTIONS AND METHODOLOGY FOR
                ASSESSING THE AIK QUALITY  IMPACT  OF"PROPOSED
                 EMISSION STANDARDS FOR lll£AVY-!)UTY  VEHICLES
     This report serves to document the input; data  used in the recent air
quality impact assessment of alternative heavy duty vehicle (IIDV)  emission
standards.  Input data^ except the ir.obile source  omission factors  calculated
by OHSA'-'C., v/ere provided for projecting ozone (0,,)  and carbon monoxide (CO)
                                                tj
levels with the Modified Rollback Model.                                    •• '

     In recognition of the regional character of  the ozone problem.,  the
emissions and air quality data used to project o^one level:; were assembled on
iui AQCi\ basis.  The 57 AQCR:; included in the data ba.se represent low altitude
t'rojis outside cf California which contain large urbanized area.'; (i.e., with
iuvula Lions greater -than 200,,000) having recorded violations of the  .12 ppm
<-•;•!(•;,!. ;•. U;ndard, "                 /                          -  -.-.

     CO t-;.fissions inventories and air quality data  were assembled  on a county
*Msi;..  A'i though CO is generally considered a localized problem, the county-is
fl:o  w.-llejt geographical area for which emissions  inventories are generally
a\v-.ilnvie on a national basis.  The 52 counties selected for this  analysis
ivp.-r.t'Mt most of those counties at low altitude  outside of California which
contuii! urbanized areas with recorded violations  of the ambient CO standard.0

     I IK? base; year ambient ozone values provided  with the current  data b..;r-;o
rti'o  these values used for the recent review of the  ozone standard. "   The base
.Viv.r conceritr-vtion (or design value) is the concentration expoc tec! to be
t%\vOi'ilctl ono day por year.  These values were obtained by applying the st.il.is--
t i•;.•:! p;-oci.',-!i:rc5 described.!!) kefere/ico^/ to ambient: ozone data for  the ye.;rs
I1-":'; fiiroucjli 19/7 in oach AOCJ?/''

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     The not impact of ozone background concentrations on the urban  areas



under consideration is assumed  to be equal  to  zero.   This proceu\ire  fo'!'lov/5



SIP gindance and  is based on the assumption that the impact of natural  back-



ground ozone concentrations on  nax'iniuin  afternoon o:-:one levels for  an urban



area is offset: by  diminishing levels of transported  ozone into the urban area


                                                       '•« 6
as control programs are  implemented on  upwind  sources..''





     The base year carbon monoxide values  were obtained from the most recent  '



compilations of CO design values for the  current reviev; of the HAAQS for

                n

carbon n;anoxide,° A  background concentration  of 1  ppm is assumed  for each



r":vUM county,7





      ''•10  lcr/t:.  base year  VOC  emissions  for  each AQCR  and source category were



 •'••  1- •••*  irotn  the National Emissions Data  System (NEDS)..  These data reflect



 '  '  '•  -ill- source.1 emission factors procedure described in .Reference  8 and the



 ''  "  '• '• ••'•'•• s'.'ii:-  by  source  category derived  from the RAPS study in Reference 9.



 1; •  c.i  pic;,., emissions calculation procedure is descriljed in detail  in Refer™



 i..-.r L\   Since NEDS  reports only a single light-duty truck category (LOT),



 f '*''  '"'• '•':•!;;.') ting factors listed in Reference 8 v/ere used to calculate 'the  '



"' • ••);i->  (fission factor for  this coiiibined category (i.e.* LDT -  LDT1  + LDT2)



 l'-';\<>  1 proviiies  a summary of  the VOC  fractions for each source category-


 ini.i'.ic.;--.!  -JM ^ju. |j-lt_;n  y0np inventory,-





     ^'-".'"(•y c;.rission  totals  were provided  for CO point and area sources.



 IMLT.I.'  ;Missions da La  also represent a  1976 NtUS base year ijiventory.

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      FoViewing  the procedures described in Reference  2,  u range oF growth
- rates in  vehicle mi las traveled (VHT) of 2 to 3 percent;,  compounded annually,
VMS  provided  for the VOC inventory.                        •      • '   '  .
                                                                    i
      For  carbon monoxide (CO) in each county, the nubile  source growth  rate?
was  assumed to  be 1  percent coiiipounoed annually.  For CO  mobile sources., this
 is  a "lower growth rate than has been historically observed for metropolitan
 areas.  It was  chosen to reflect the fact that carbon monoxide generally is a
 localized problem v/here traffic density is already high  and that growth in
 these areas vrill not be as great as for the broader metropolitan areas,

      The stationary growth and retirement rates from  Reference 2 were used  for
 \,:'<.'. stationary  sources.  A summary or these growth rate assumptions by source
 •  ' •;:..:>' is provided in Table 2.

        •  , .: r,,l ••; for CO stationary sources were estimated from economic
          .• .. 111:'  ;our_ groupings of sources:  electric: generation, industrial
     • •• ;. •> «*r-.a sources and other point sources.  Stationary  carbon monoxide
        .  . r.1 C-SY c!;••:! to yrcv; at a rate of 3.2 percent compounded annually.

       !; ' '•'•  :>  !.v.tioiusry source emissions control technology asr.innptions
          •  i'i Kr!.; once 2 anci summarised in Table 2 v:ere used,

       i   «.•:: rc'l iccjl.nolociy assumptions for CO sources used in this analysis
           •  •-.!•:!•. d in Rerei-ei-re 7.  These control technology  assumptions were
         i :...: ixuitr.il  Lechiio lorr,- \-;i th successively more strinyent controls
 •   •• . • /;--fd  Truii lf;;-0 to 1990.

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     The source contribution factors  equal  1.0  for  all  VOC source categories.



This equal  weighting of emissions  from  all  sources  reflects the regional



character of these pollutants.





     A stationary-source contribution factor less  than  1.0 v/as entered for



each carbon monoxide stationary .source  category,'  These factors account for



the fact that CO "hot spots" are typically  located  in areas of high traffic



density which usually are not associated  with significant stationary sources



of carbon monoxide.  The carbon monoxide  stationary source contribution factors



are 0.0 for point sources and 0.2  for area, sources.   These adjustment factors



were selected after considering ths  results  from dispersion models for pov/er



plants and industry and a'review of  the relationship betv/een traffic density



and carbon monoxide levels in several situations.





     O/onc1 air quality projections are  i .acie using  both  linear rollback and the



\L"..\,  Ihe  inclusion of the ef feetr that the prevail inq  MMC/hO", ratio has on
                                                              x


lh" i;;; ;C-o;;:one relationship makes  F.KHA  potentially  more accurate than rollback



in  predicting the effect of HMHC changes  on future  o;'.one levels.  To facilitate



the application of FJS'.MA to national  strategy assessments,  tv/o simplifyinc;



assumptions were made.  First,  a 6-9 a.m.  i;M!iC/i«0 .  ratio of 9.13:1 v/as assumed
                                                X


for all urban areas. '  Secondly., U0v emissions  arc  assumed to remain constant
                                  f\


froii) the base year to the projection year.





     i'he uses, limitations and, basic assumptions of each, of these procedures



are discussed in Reference 11.   As noted.in  this rrport, these modeling



procedures are best applied in a relative sense.   Thus, when comparing emission



control strategies, one should focus  on the  relative: differences in air quality

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   __.;-; and attainment status amoncj the various alternatives,  rather than the
                         i
   ., ,]titc predictions.



     In sundry>  it should  be noted  that the data assumptions and  methodology

,ii:...! in this  analysis  were  chosen  specifically to assess the  impact,of  emissions

control  strategies  which  are national  in scope.   For planning in any  specific

(jcooraphic  area,  more  detailed  analyses  would be  required.

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3.
 .
8.
IL delivers and 0.  R,  Morris,  "Rollback Modeling:  Basic and  Modified,"
JAPCA,  ?•$> 9''3> September 1975'.

Cost  a_nd Economic^ Impact ^^^^''^_j^\Jjl^-]^^^L^^^^^^^-^.

T^^rro^^i^r ^-ol^^l'^r^ili^y,  P(;5r;cil"ch ~Tr i ang] e. Park, North  Carol i na,
February 197S.

"Methodologies for Conducting  Recjdatory  Impact Analyses of Ambient
Air Quality Standards  for Carbon  Monoxide  (Prel inrinary Draft}," SRI»
International > Stii/te-ir.ber 1979,

G u i ci f • 1 i n a f o r_ _I _n t. P ijl^^l0.1! ,9f_ P7-9!;.?. ZlirJ5i:LlJJ:Y...§^M:Lrl'-?.s
HPA~^D[J7^-79-L;Od,  U.S.  hnvirdiKiiani'as  Protech'on Aceiicy, f-lesssrch Triancjl!
I^'irkj  North Carolina,  January  19/9,

Workshops on  RKquirr-niGnts for  rlc'iati.ai ni;:an t Area__Plaij5:j	Conmi_l_aflo_n
fff"IVos'sri'T'atioj'.s.   U.S. hnvirOiT.vjrita.i Protection /;.aef";cy> Research Trianu"
Y'liT-irr "i;o"rTJr~C'a'ro'l i na >  Apr i 1  197c«.

PriV'-r'-irc-:-; for Oiianti rvinci  !-U;lat'ionshi j")-.7.  batv/cei"; f'hotochanical  Oxic!;-r(tr>
 as,,  i r ••••••;•• :.r.;T,:   'aa':;or (n;:.;  !;oci'.:.^:.ii:a ^ cri,  Li-vV-^G'J/ ^/ /-UI-- i o 5  U.o. ;:nviron!V,&ni
 I'j iu.::i;i.it>"T A;jci'fcy^"Kcsl;!a'i:cir"iria?;i.iTcJ't'Tir^,  North Carol ii';a,   February  1973.

 nAn  /'irOysis  of  Alternative  Motor Yohiclo Emission Standards,"  prepared
 hy {!•.•: U.S. Uopartincnt of Transportation, U.S.  Environiirsntal  Protection
 (\[\>..  Liiviroriii^ntaT ProtcctT6n"7\uiriky,"l,:a^rirK;ton, D.C.,  March 1978.

 j!APS Sn;d/: J^oirii and Area_ Source fM-canic^Ein^iop.  Inventory,
 i PA-i ..'J/•»-7.-.i-L)^o,  U.S. iinvi ronfi;cn:ai Protec tion "A(;-5ric77" Hasearch Triangle
 Park,  i;orrli Carolina, 197H.

 A;9;!'>,  Voh^pj^J!,  rPA-4oO/2-75-029, U.S. environmental  Protection
 ).fj..:icy.,  Pcbi/arc'ir Triangle Par!;,  Htirth Carolina, 1975.

 kc(>£--..,'-ii'n j'^ions  arid_ 'fechnic;al  i>asis of_!:Vpccck;res  for Quantify! nc

 //-u/iu, U.b.  i.-:vircHi;,:;:ntai  i^roteclibn /.qancy/"p'c.-sccr'ciT'iFi'anql(.• Park,
 fJorth  Curalina,  Kovcinber 1977.

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                                   TABLE  I/
          I'jjinS  Report; of Volatile Organic  Coinpcunds


     A proqiv.r.i  war. ciovclonet!  to estimate: 'VOC er.iisr, ionr. from i.'EDS
.O'.M-CC." ca tei;or i or, ar> a  percentage of  the  total  hydrocf.r'ocns cul-
rulatec! in  the  H1:DS user  file.-   The percentacjcs used for  each
co.tec;ury v;orc  derived lYem  the  publication, "P./M'S  S'ci;dy:   Point
anJ Aro.-i Sourco Orqanic  ["uission Inventory" (Pubi ica t i on  EPA-600/
(•,-7C-Ul'o) iiiul  arc i: a bu 1 a t CK!  bt-.low:
                                                                 f, VOC
V-  ' ° •'•:-. 'Co  Ca Ler, ory              •                         oj_J:|)j.^ TO tal  HC
        ,  Tr^iu.portation and Markctiiuj  of       •        '.      92%
             i i .- M -'us  Scurcc:^   •
          ' i •. . 'M~ 1. ion
      '  .*•;.! '..' i:, :.'..- Disposal
      •• »•!'.• . I , Ayr icul tural ,  and
        (H !;;•;• OJKMI  P.unrinrj
      iiiijiv./.v/ VnhicTcs
           a)  Liyht  Duty Automobiles                          05^
           b)  Lir,irt  Duty Trucks                                85%
           c)  H-avy  Duty Gasoline  Trucks       '               85:i:
           d)  Heavy  Duty Diesel  Trucks                        CJ/T>
           o)  I-',G torcycles                                     100'^
      Ofv--iiir;!iv/jy  Veincles                            '          90r'j
                '
                                                                 9 / '.•;
      '•'<'-:  J. ror.di,  i.'Anii, 12/1/78

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                                           I .
                                   T/ifiLE 2;       •  .
                                            {

         '  o        Emissions Grov/th  and Control Assumptions

              For  Stationary Sources of I!on~meth?.n2 Hydrocarbons

                           Grov/lh  '                             '
                           Rate*         Retirement        is12 PS               RAC.T   i
                          Lo  Hi         Rate*'            Kf ficuM'icy**   .   Kf i'ici c-:ncv -
.   ;•.[ role urn
 '• ;,...;ineric:s      .          2,3             4                  85        .        90


   ,,- • :>••,;>,-.!• I at ion and   .                          >,.               •
      ' ••'.i:u-;  of Pet.ro          .                 \ ''•
2,3
3,4
1,3
-1,0
0,3
• 4
3
3
2
0
' 80
45
80
• o
0
• 80
3 '5
-to
0
•o''
                   "::t  emissions in identifiable  sub-categories after
                 • •r (:\U;Ui;g tevels of control,  iiSPS  only "applies to
                .'  VIMS RACT applies to existing  sources,.

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