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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