MOVESZOlOb:
Additional Toxics Added to MOVES
&EPA
United States
Environmental Protection
Agency
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MOVESZOlOb:
Additional Toxics Added to MOVES
Assessment and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
United States
Environmental Protection
Agency
EPA-420-B-12-029a
May 2012
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Table of Contents
Table of Contents
i. Introduction 4
2. Gasoline Vehicles and Trucks 7
2.1. Exhaust 7
2.1.1. Gaseous Hydrocarbons 7
2.1.2. Polycyclic Aromatic Hydrocarbons 8
2.1.3. Metals 9
2.1.4. Dioxins andFurans 11
2.2. Evaporative and Permeation 12
3. Diesel Vehicles and Trucks 14
3.1. Exhaust 14
3.1.1. Gaseous Hydrocarbons 14
3.1.2. Polycyclic Aromatic Hydrocarbons 16
3.1.3. Metals 18
3.1.4. Dioxins 18
3.2. Evaporative 19
Appendix A
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1. Introduction
The previous version of MOVES, MOVES 2010a, estimated emissions for only a limited
number of air toxics from highway vehicles, including benzene, 1,3-butadiene, formaldehyde,
acetaldehyde, acrolein, naphthalene, and ethanol.1 Furthermore, estimation of air toxic
emissions was done largely by relying on algorithms carried over from MOBILE6.22 and the
National Mobile Inventory Model (NMEVI).3 Exceptions included addition of toxic to
hydrocarbon ratios for ethanol.
For benzene, 1,3-butadiene, formaldehyde and acetaldehyde from light duty gasoline
vehicles and trucks, algorithms calculated toxic to VOC ratios using fuel parameters. These
algorithms were derived from U. S. EPA's Complex Model for Reformulated Gasoline,
developed in the early 1990's for the Federal Reformulated Gasoline Rule.4 MOVES 201 Ob
continues to rely on these algorithms for exhaust and non-permeation evaporative emissions.
Acrolein, naphthalene and ethanol were estimated using simple toxic to VOC ratios. Ratios for
ethanol and non-permeation evaporative emissions of naphthalene are the same for gasoline
vehicles in this version of the model, but ratios for exhaust naphthalene have been updated.
Acrolein ratios are the same for light-duty gasoline vehicles in both versions of the model;
however, acrolein ratios for heavy-duty gasoline vehicles differed from light-duty gasoline
vehicles in MOVES210a, while in MOVES2010b, the ratios for heavy-duty gasoline vehicles are
the same as light-duty gasoline ratios. Algorithms for diesel vehicles have all been updated.
None of the other toxics estimated using EPA's National Mobile Inventory Model
(NMEVI) were included in draft MOVES2010a. However, these HAPs have all been added to
MOVES2010b. In NMTM, for other light duty gasoline toxics, and for all toxics from other
vehicle and engine types, the algorithms took one of three forms: toxic to VOC ratios (for
gaseous HAPs), toxic to PM ratios (PAHs), and basic emission rates (metals).5 In
MOVES2010b, the same approach is used, except for PAHs. PAH mass emissions are
apportioned into the gas and particle phase, and gas phase PAHs are estimated using toxic/VOC
ratios and particle phase PAHs were estimated using toxic to OC2.5 (organic carbon less than 2.5
microns) ratios.
The algorithms in NMIM were developed over 10 years ago. More recent data are now
available, representing more modern vehicles and engines, and fuels more representative of what
is currently being sold. For many vehicle types, data used to develop algorithms were also very
limited, and quality of estimates can be enhanced by addition of more data. U. S. EPA has
analyzed more recent data, reflecting advanced emission control technology and modern fuels,
and added more data for older technology vehicles to enhance the quality of emission rate
estimates.
MOVES2010b includes all air toxic pollutants in the National Emission Inventory (NET) and
National Air Toxics Assessment (NATA) that are emitted by mobile sources. This list of
pollutants is provided in Table 1.1. These pollutants are organized into four categories:
1) Gaseous hydrocarbons
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2) Polycyclic aromatic hydrocarbons (PAHs) - These hydrocarbons which contain fused
aromatic rings can be found in the gas phase, particle phase, or both, depending on
properties of the compound, particle characteristics, and atmospheric condtions
3) Dioxins and furans - polychlorinated organic compounds which are persistent and
bioaccumulative
4) Metals
The pollutant "xylenes" represents the sum of emissions from three isomers of xylene — o-
xylene, m-xylene, and p-xylene. MOVES also reports three forms of mercury - elemental
gaseous, divalent gaseous (a reactive form) and paniculate phase. Moreover, arsenic is reported
as the total mass of all organic and inorganic arsenic compounds. However, emissions data for
mobile sources all come from measurements of elemental arsenic mass.
Table 1. Air toxics included in MOVES 2011, along with MOVES PollutantTD numbers and
NEI pollutant codes.
Pollutant
Gaseous Hydrocarbons
1,3 -Butadiene
2,2,4-Trimethylpentane
Acetaldehyde
Acrolein
Benzene
Ethanol
Ethyl Benzene
Formaldehyde
Hexane
Methyl Tert Butyl Ether (MTBE)
Propionaldehyde
Styrene
Toluene
Xylenes
PAHs
Acenaphthene particle
Acenaphthylene particle
Anthracene particle
Benz(a)anthracene particle
Benzo(a)pyrene particle
Benzo(b)fluoranthene particle
Benzo(g,h,i)perylene particle
Benzo(k)fluoranthene particle
Chrysene particle
Dibenzo(a,h)anthracene particle
Fluoranthene particle
MOVES
Pollutant ID
24
40
26
27
20
21
41
25
42
22
43
44
45
46
70
71
72
73
74
75
76
77
78
68
69
CAS Number
106990
540841
75070
107028
71432
64175
100414
50000
110543
1634044
123386
100425
108883
1330207
83329
208968
120127
56553
50328
205992
191242
207089
218019
53703
206440
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Pollutant
Fluorene particle
Indeno(l,2,3,c,d)pyrene particle
Naphthalene particle
Phenanthrene particle
Pyrene particle
Acenaphthene gas
Acenaphthylene gas
Anthracene gas
Benz(a)anthracene gas
Benzo(a)pyrene gas
Benzo(b)fluoranthene gas
Benzo(g,h,i)perylene gas
Benzo(k)fluoranthene gas
Chrysene gas
Dibenzo(a,h)anthracene gas
Fluoranthene gas
Fluorene gas
Indeno(l,2,3,c,d)pyrene gas
Naphthalene gas
Phenanthrene gas
Pyrene gas
Dioxins and Furans
2,3,7,8-Tetrachlorodibenzo-p-Dioxin
1,2,3,7,8-Pentachlorodibenzo-p-
Dioxin
1,2,3,4,7,8-Hexachlorodibenzo-p-
Dioxin
1,2,3,6,7,8-Hexachlorodibenzo-p-
Dioxin
1,2,3, 7,8, 9-Hexachlorodibenzo-p-
Dioxin
1,2,3,4,6,7,8-Heptachlorodibenzo-p-
Dioxin
Octachlorodibenzo-p-dioxin
2,3,7,8-Tetrachlorodibenzofuran
1,2,3,4,6,7,8-
Heptachl orodib enzofuran
1,2,3,4,7,8,9-
Heptachl orodib enzofuran
1,2,3,4,7,8-Hexachlorodibenzofuran
1,2,3, 6,7,8-Hexachlorodibenzofuran
1,2,3, 7,8, 9-Hexachlorodibenzofuran
MOVES
Pollutant ID
81
82
23
83
84
170
171
172
173
174
175
176
177
178
168
169
181
182
185
183
184
142
135
134
141
130
144
131
136
144
137
145
144
146
CAS Number
86737
193395
91203
85018
129000
83329
208968
120127
56553
50328
205992
191242
207089
218019
53703
206440
86737
193395
91203
85018
129000
17466016
40321764
39227286
57653857
19408743
35822469
3268879
51207319
67562394
55673897
70648269
57117449
72918219
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Pollutant
1,2,3,7,8-Pentachlorodibenzofuran
2,3,4,6,7,8-Hexachlorodibenzofuran
2,3,4,7,8-Pentachlorodibenzofuran
Octachlorodibenzofuran
Metals
Mercury (elemental gaseous)
Mercury (divalent gaseous)
Mercury (particulate)
Arsenic compounds
Chromium (Cr3+)
Chromium (Cr6+)
Manganese Compounds
Nickel Compounds
MOVES
Pollutant ID
135
143
138
133
60
61
62
63
64
65
66
67
CAS Number
57117416
60851345
57117314
39001020
200
201
202
93
16065831
18540299
7439965
7440020
This document provides data methodologies and sources for gasoline vehicles and trucks
running on EO, E10 and MTBE blends, and diesel vehicles and trucks. Toxics inputs for
MOVES do not vary by temperature or operating mode. Ambient temperature also affects these
ratios, but we assumed toxic emission of gaseous toxics and PAHs change proportionally with
VOC and PM as temperature varies. In general, data are inadequate to account for temperature
effects on toxic to VOC and toxic to PM ratios. Emission rates for metals are assumed to be
independent of operating mode and temperature; very little data exist to account for impacts of
these parameters.
2. Gasoline Vehicles and Trucks
2.1. Exhaust
2.1.1. Gaseous Hydrocarbons
MOVES 201 Ob provides the capability to model toxic emissions from vehicles running
on gasoline, E10, and MTBE blends. E10 is defined as fuel containing ethanol which is greater
than or equal to 5% by volume or ETBE greater than or equal to 5% by volume. For additional
HAPs, the same toxic to VOC ratios are used for MTBE blends and EO. For 2003 and earlier
vehicles, toxic to VOC ratios for EO an E10 were developed by Sierra Research6 using estimates
from EPA's SPECIATE 4.2 database (Table 2). Ratios for LOG vehicles were used for all
gasoline vehicle classes.
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Table 2. Toxic to VOC ratios for selected air toxics from Tier 1 and earlier gasoline vehicles and
trucks.
pollutant
Name
2,2,4-Trimethylpentane
Ethyl Benzene
Hexane
Propi onal dehy de
Styrene
Toluene
Xylene
EO
0.01823
0.02147
0.01570
0.00086
0.00108
0.09619
0.07814
E10
0.01849
0.01932
0.01593
0.00086
0.00097
0.08657
0.07032
For 2004 and later vehicles running on EO and E10, ratios for additional gaseous HAPs
for EO and E10 were obtained from Phase 1 of the EPAct test program. These profiles were
based on tests from 3 vehicles.7 Toxic to VOC ratios for E10 are used in MOVES for all
gasoline above 5% ethanol by volume. Ratios are provided in Table 3.
Table 3. Toxic to VOC ratios for selected air toxics from Tier 2 gasoline vehicles and trucks
pollutant
Name
2,2,4-Trimethylpentane
Ethyl Benzene
Hexane
Propionaldehyde
Styrene
Toluene
Xylene
EO
0.03188
0.01683
0.00279
0.00122
0.00085
0.07542
0.06127
E10
0.01227
0.01660
0.02911
0.00054
0.00083
0.07440
0.06047
2.1.2. Polycyclic Aromatic Hydrocarbons
As mentioned previously, in the NMEVI model8, PAH emissions were estimated as ratios
to PM. This approach was used, even though PAHs are found in the gas, semi-volatile and
particle phase, because there is generally reasonable correlation between PAH and PM
emissions.9'10 However, for MOVES 201 Ob, PAH mass emissions are apportioned into the gas
and particle phase, and gas phase PAHs are estimated using toxic/VOC ratios and particle phase
PAHs were estimated using toxic to OC2.5 (organic carbon less than 2.5 microns) ratios.
Although partitioning of PAHs into the gas and particle phases depends on concentration,
temperature and other factors, MOVES applies one set of allocation factors under all conditions
in order to streamline data processing. These allocation factors were developed by Sierra
Research11 using estimates from EPA's SPECIATE 4.2 database12 and information on
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compounds' physical and chemical properties. Table 4 provides molecular weights and
allocation factors. The allocations from SPECIATE were based on medium duty diesel engine
data. Using PAH and VOC emissions data from Norbeck et al. (1998) and the allocation
factors in Table 4, the toxic/VOC ratios in Table 5 were developed. Norbeck et al. data were
also used to develop toxic/PMio ratios. These ratios were then converted to toxic/OC2.s ratios for
start and running operation. These conversions were made using assumptions that 90% of PMio
is PM2.515, 87.3% of running PM2.5 is OC, and 66.6% of start PM2.5 is OC. OC percentages of
PM2.5 were obtained from MOVES runs. PAH to VOC and PAH to OC2 5 ratios do not vary
between EO and E10 fuels.
2.1.3. Metals
Metals emissions can result from trace level contamination of fuel and engine oil, as well
attrition from exhaust emission components. MOVES estimates metal emissions using gram per
mile emission factors. Emission factors for metals remain unchanged from the values used in
NMEVI (Table 6). Emission factors for chromium, magnesium and nickel are obtained
from a paper by Ball, 1997.16 Eighteen percent of chromium was assumed to be hexavalent,
based on combustion data from stationary combustion turbines that burn diesel fuel.17 Emission
factors for mercury were obtained from a 2005 EPA test program. Documentation describing
development of these emission factors can be found in Appendix A. Emission factors for arsenic
were developed from data reported for tunnel tests.
fuel types.
18
Metal emission rates do not vary among
Table 4. PAH gas/particle phase allocation factors
PAH Species
Acenapthene
Acenaphthylene
Anthracene
Benz(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
B enzo(k)fluoranthene
Chrysene
Dibenzo(a,h)anthracene
Fluoranthene
Fluorene
Indeno( 1,2,3 -cd)pyrene
Phenanthrene
Pyrene
Molecular
Weight
154
152
178
228
252
252
276
252
228
278
202
166
276
178
202
Allocation Fraction
PM Phase
0
0
0.466
0.723
1
1
0.773
1
0.823
1
0.516
0.215
1
0.335
0.552
Gaseous Phase
1
1
0.534
0.277
0
0
0.227
0
0.177
0
0.484
0.785
0
0.665
0.448
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Table 5. PAH/VOC and PAH/PM ratios for gasoline vehicles and trucks.
PAH
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Chrysene
Dibenz(a,h)anthracene
Indeno(l,2,3-
cd)pyrene
Acenaphthene
Acenaphthalene
Anthracene
Benzo(ghi)perylene
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Pyrene
Start
Fraction of
OC25
0.0001237
0.0001711
0.0002032
0.0002032
0.0001408
0.0000000
0.0001283
0.0000000
0.0000000
0.0006577
0.0003306
0.0007834
0.0005425
0.0000000
0.0014184
0.0011450
Running
Fraction of
OC25
0.0000944
0.0001306
0.0001551
0.0001551
0.0001075
0.0000000
0.0000979
0.0000000
0.0000000
0.0005020
0.0002524
0.0005980
0.0004141
0.0000000
0.0010827
0.0008740
Fraction of
VOC
0.0000007
0.0000000
0.0000000
0.0000000
0.0000005
0.0000000
0.0000000
0.0000185
0.0001040
0.0000114
0.0000015
0.0000111
0.0000300
0.0022928
0.0000427
0.0000141
Table 6. Metal emission factors for gasoline vehicles and trucks.
Pollutant
Chromium 6+
Chromium 3+
Manganese
Nickel
Elemental Gas Phase Hg
Reactive Gas Phase Hg
Particulate Hg
Arsenic
Emission Rate (g/nii)
8.9x10-'
4.1X10'6
1.7xlO-b
3.6X10'6
l.lxlO'7
9.9xlO'y
4.0xlO'lu
2.3xlO-b
10
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2.1.4. Dioxins and Furans
MOVES estimates emissions for 17 dioxin and furan congeners (Table 7). The emissions
are estimated using mg/mile emission factors. These emission factors were obtained from EPA's
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dioxin assessment. They do not vary among fuel types.
Table 7. Dioxin emission factors for gasoline vehicles.
Pollutant
2,3,7,8-TCDD TEQ
1,2,3,7,8-Pentachlorodibenzo-p-Dioxin
1,2,3, 4,7, 8-Hexachlorodibenzo-p-Dioxin
1,2,3,6,7,8-Hexachlorodibenzo-p-Dioxin
1,2,3, 7,8, 9-Hexachlorodibenzo-p-Dioxin
1,2,3,4,6,7,8-Heptachlorodibenzo-p-
Dioxin
Octachlorodibenzo-p-dioxin
2,3,7,8-Tetrachlorodibenzofuran
1,2,3,7,8-Pentachlorodibenzofuran
2,3 ,4, 7, 8-Pentachlorodib enzofuran
1,2,3, 4,7, 8-Hexachlorodibenzofuran
1,2,3,6,7,8-Hexachlorodibenzofuran
1,2,3, 7,8, 9-Hexachlorodibenzofuran
2,3,4,6,7,8-Hexachlorodibenzofuran
1,2,3,4,6,7,8-Heptachlorodibenzofuran
1,2,3,4,7,8,9-Heptachlorodibenzofuran
Octachl orodib enzofuran
Mg/mi
8.27E-10
3.70E-10
3.87E-10
7.92E-10
4.93E-10
5.95E-09
4.70E-08
2.76E-09
1.32E-09
9.68E-10
1.09E-09
1.16E-09
3.17E-10
1.36E-09
1.21E-08
3.87E-10
1.37E-08
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2.2. Evaporative and Permeation
Toxic to VOC ratios for evaporative non-permeation emissions of benzene, MTBE,
ethanol and naphthalene remain unchanged from those in MOVES2010a. In summary, benzene
and MTBE ratios are estimated using algorithms originally developed for MOBILE 6.2.
However, evaporative emissions processes for MOVES differ from those in MOBILE6.2. Thus,
algorithms for hot soak in MOBILE6.2 are used for vapor venting and refueling vapor loss in
MOVES, and algorithms for running loss are used for fuel leaks and refueling spillage loss
(Table 8). Ratios for naphthalene and ethanol are given in Table 9.
Ratios for the additional air toxics found in evaporative non-permeation emissions (2,2,4-
trimethylpentane, ethyl benzene, hexane, propionaldehyde, toluene and xylenes) were obtained
from profiles developed for EPA by Environ Corporation, using data from the Auto/Oil test
program conducted in the early 1990's.20 These ratios are also given in Table 9. For all
pollutants except benzene, ratios are the same for all types of non-permeation evaporative
emissions. The ratios for 10% ethanol are used for all fuels with greater than or equal to 5%
ethanol and less than 12%.
Table 8. Toxic/VOC algorithms for benzene and MTBE gasoline vehicle evaporative emissions.
Polluta
nt
Process
Toxic Fraction Equation (Toxic/VOC)
Benzene
Vapor Venting/Refueling
Vapor
Fuel Leaks/Spillage
(-o.03420*OXY - o.o8o274*RVP + i.4448)*BNZ/ioo
(-o.03420*OXY - o.o8o274*RVP + i.4448)*BNZ/ioo
MTBE
Vapor Venting/Refueling
Vapor
Fuel Leaks/Spillage
(24.205 - 1.746*RVP)*MTBE/1000
(17.8538 - 1.6622*RVP)*MTBE/1000
Note: OXY = wt% oxygen
RVP = Reid vapor pressure in psi
BNZ = vol% benzene
MTBE = vol% MTBE
12
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Table 9. Evaporative Toxic/VOC ratios for other toxics from gasoline vehicles (Auto/Oil).
Pollutant
Ethanol
Naphthalene
2,2,4-Trimethylpentane
Ethyl Benzene
Hexane
Toluene
Xylene
EO
0.00000
0.00040
0.01984
0.02521
0.02217
0.09643
0.07999
E10
0.11896
0.00040
0.03354
0.01721
0.02536
0.14336
0.06423
The composition of permeation emissions differs significantly from other types of
evaporative emissions. Work to better characterize these permeation emissions was recently
conducted for the Coordinating Research Council.21'22 These data were used to develop the toxic
to VOC ratios in Table 10. Data from the CRC E-65 study22 were used for ethanol, while data
from the CRC E-77-2b study were used for the rest of the air toxics in Table 10.21 For the CRC
E-77-2b study, data from 3-day diurnal tests on vehicles meeting Tier 1 and near zero
evaporative emission standards were used. Toxic to VOC ratios for EO and E10 were estimated
by averaging data from gasolines of different RVPs.
Toxic to VOC ratios for benzene, MTBE, and naphthalene are not found in Table 10. For
benzene, the diurnal emissions algorithm from MOBILE6.2 was used instead, since this
algorithm accounts for impacts of changing oxygenate, RVP and fuel benzene levels. However,
the CRC E-65 study suggests that the ratio of benzene from permeation to total VOC is about
1.77 times higher than the ratio associated with evaporation.23 Thus the diurnal emissions
algorithm was multiplied by 1.77. This algorithm is:
1.77[(-0.02895*OXY - 0.080274*RVP + 1.3758)*BNZ/100]
In the absence of data on permeation emissions for MTBE, the resting loss algorithm from
MOBILE6.2 was used:
(22.198-1.746RVP)*MTBE/1000
For naphthalene, the toxic to VOC ratio for non-permeation evaporative emissions was also
applied to permeation.
13
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Table 10. Gasoline vehicle permeation toxic/VOC ratios for air toxics except benzene,
naphthalene and MTBE (CRC E-65 and E-77-2b).
Pollutant
2,2,4-Trimethylpentane
Ethyl Benzene
Hexane
Toluene
Xylene
Ethanol
EO
0.036
0.003
0.050
0.110
0.016
E10
0.024
0.001
0.065
0.101
0.011
0.333
3. Diesel Vehicles and Trucks
Toxic/VOC ratios, PAH/VOC ratios, PAH/PM ratios and metal emission factors were
developed for exhaust emissions from heavy-duty diesel vehicles and applied to all diesel vehicle
categories. There are no separate emission ratios or factors for diesel engines running on
biodiesel fuels or synthetic diesel fuels, due to very limited data.
3.1. Exhaust
3.1.1. Gaseous Hydrocarbons
The composition of VOCs for heavy-duty diesel engines without model year 2007 and
later emission controls versus those engines with such controls vary significantly. Thus, we
developed one set of toxic to VOC ratios for pre-2007 diesel engines and another set for 2007
and later engines. Since extended idle emissions associated with auxiliary power units (APUs)
are not subject to 2007 standards, toxic to VOC ratios for pre-2007 diesel engines were used for
them. Since light-duty diesels comprise a very small portion of the fleet, the same ratios were
applied to all diesel vehicle classes to streamline modeling.
EPA relied on a database compiled for the Coordinating Research Council (CRC E-75)
and National Renewable Energy Laboratory (NREL) to develop toxic to VOC ratios for pre-
2007 engines.24 This database was developed from a literature survey and included data from 13
different studies. The studies included in this database were conducted in a number of different
countries, included heavy-duty and light-duty engines, a variety of diesel and biodiesel fuels, and
a number of different operating modes and cycles. For 2,2,4-trimethylpentane, hexane,
propionaldehyde, and toluene, toxic to VOC ratios developed by Sierra Research from CRC E-
75 data were used. The methodology they used to develop ratios is described in detail in their
technical report. Data from tests using non-conventional diesel fuel (Fischer-Tropsch, bioDiesel,
ethanol-Diesel blends, emulsified fuel, European blends, and other obvious research fuels) were
excluded, as were data from non-heavy duty engines. The ratios are provided in Table 11.
Toxic to VOC ratios for benzene, 1,3-butadiene, formaldehyde, acetaldehyde, acrolein,
naphthalene, ethylbenzene, styrene and xylenes were developed by EPA from the E-75 database.
14
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We relied on United States data from heavy-duty diesel engines running on conventional diesel
fuels, collected on test-cycles representative of real world operation. Some studies measured
emissions over distance, while other studies measure emissions relative to brake horsepower.
For studies which measured emissions relative to distance, we calculated mean emissions per
mile for toxics and VOC, then calculated a ratio of toxics to VOC. For studies which measured
emissions relative to brake horsepower hour, we calculated mean emissions per brake
horsepower hour for toxics and VOC, then calculated a second ratio of toxics to VOC. We then
calculated a composite ratio using sample size to weight the two ratios. The resulting ratios are
provided in Table 11.
For 2007 and later heavy-duty diesels, and 2004 and later light-duty diesels which meet Tier 2
vehicle standards, advanced emission controls change the composition of VOCs. For these
engines, we relied on speciated emissions data from the Advanced Collaborative Emissions
Study (ACES), directed by the Health Effects Institute and Coordinating Research Council, with
participation from a range of government and private sector sponsors.25 Detailed emissions data
from the study were provided to EPA at the request of the Coordinating Research Council.
The data were collected on four engines on several test cycles with low sulfur diesel fuel. EPA
used data from a 16-hour transient cycle. Toxic to VOC ratios obtained from the ACES data are
provided in Table 12.
Table 11. Toxic to VOC Ratios for pre-2007 diesel engines (CRC E-75).
Pollutant
1,3 -Butadiene
2,2,4-Trimethylpentane
Acetaldehyde
Acrolein
Benzene
Ethyl Benzene
Formaldehyde
Hexane
Propi onal dehy de
Styrene
Toluene
Xylenes
Toxic/VOC
0.002918
0.001808
0.035559
0.006622
0.007835
0.002655
0.078225
0.00197
0.00468
0.001312
0.00433
0.003784
15
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Table 12. Toxic to VOC Ratios for 2007 and later diesel engines.
Pollutant
1,3 -Butadiene
2,2,4-Trimethylpentane
Acetaldehyde
Acrolein
Benzene
Ethyl Benzene
Formaldehyde
Hexane
Propi onal dehy de
Styrene
Toluene
Xylenes
Toxic/VOC
0.00080
0.00782
0.06934
0.00999
0.01291
0.00627
0.21744
0.00541
0.00314
0.00000
0.02999
0.03800
3.1.2. Polycyclic Aromatic Hydrocarbons
As with gasoline vehicles, PAH mass emissions from diesel engines were apportioned
into the gas and particle phase, using a single set of allocation factors for all conditions. Gas
phase PAHs were estimated using toxic/VOC ratios and particle phase PAHs were estimated
using toxic to OC2.5 ratios. Toxic to VOC and toxic to PM2.s ratios for pre-2007 diesel engines
were developed by EPA from the E-75 database. Toxic to PM2.5 ratios were converted to toxic
to OC2.5 ratios using OC2.5 to PM2.5 percentages from MOVES. We relied on United States data
from heavy-duty diesel engines running on conventional diesel fuels, collected on test-cycles
representative of real world operation. It should be noted that for some PAHs, there were
substantially more data than for others; thus the level of confidence in emission factors varies
among individual compounds. For instance, while data from 66 tests were available for
acenaphthene, data from only two tests were available for dibenz(a,h)anthracene. Table 13
provides VOC and PM ratios for PAHs from these older technology engines.
For 2007 and later diesels, advanced emission controls change the composition and
reduce the total mass of PAHs. For these engines, we relied on speciated emissions data from
the ACES study. Table 14 provides VOC and OC2.5 ratios for PAHs from these newer
technology engines.
16
-------
Table 13. PAH/VOC and PAH/ OC2.5 ratios for pre-2007 diesel engines.
PAH
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Chrysene
Dibenz(a,h)anthracene
Indeno(l,2,3-
cd)pyrene
Acenaphthene
Acenaphthalene
Anthracene
Benzo(ghi)perylene
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Pyrene
Start
Fraction of
OC25
0.0002100
0.0000789
0.0000234
0.0000033
0.0001327
0.0000032
0.0000060
0.0000000
0.0000000
0.0001058
0.0000038
0.0004058
0.0001818
0.0000000
0.0004187
0.0005865
Running
Fraction of
OC25
0.0005806
0.0002180
0.0000648
0.0000091
0.0003667
0.0000087
0.0000166
0.0000000
0.0000000
0.0002924
0.0000104
0.0011217
0.0005025
0.0000000
0.0011574
0.0016213
Fraction of
HC
0.0000445
0.0000000
0.0000000
0.0000000
0.0000235
0.0000000
0.0000000
0.0003210
0.0005009
0.0002353
0.0000276
0.0006108
0.0005914
0.0090464
0.0019446
0.0007577
Table 14. PAH/VOC and PAH/PM ratios for 2007 and later diesel engines.
PAH
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Chrysene
Dibenz(a,h)anthracene
Indeno(l,2,3-cd)pyrene
Acenaphthene
Acenaphthalene
Anthracene
Benzo(ghi)perylene
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Pyrene
Start
Fraction of
OC25
0.0000015
0.0000061
0.0000026
0.0000026
0.0000046
0.0000018
0.0000009
0.0000000
0.0000000
0.0000488
0.0000004
0.0000896
0.0000990
0.0000000
0.0007886
0.0000859
Running
Fraction of
OC25
0.0000010
0.0000042
0.0000018
0.0000018
0.0000031
0.0000013
0.0000006
0.0000000
0.0000000
0.0000334
0.0000003
0.0000613
0.0000677
0.0000000
0.0005395
0.0000588
Fraction of
HC
0.0000003
0.0000000
0.0000000
0.0000000
0.0000005
0.0000000
0.0000000
0.0000526
0.0000853
0.0000304
0.0000002
0.0000457
0.0001963
0.0163278
0.0008507
0.0000379
17
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3.1.3. Metals
Emissions factors for chromium, magnesium, and nickel from pre-2007 diesels were based
on data from the CRC E-75 test program. Emission factors for 2007 and later diesels are from
the ACES test program. Emission factors for mercury and arsenic were obtained from the same
2005 EPA test program and tunnel study as the gasoline vehicle emission factors. They do not
vary with emission control technology. Table 15 provides metal emission factors for heavy duty
engines.
Table 15. Metal emission factors for diesel vehicles and trucks.
Pollutant
Chromium 3+
Chromium 6+
Manganese
Nickel
Elemental Gas Phase Hg
Reactive Gas Phase Hg
Particulate Hg
Arsenic
Pre-2007
Emission Rate (g/nii)
5.6x10-6
1.2xlO-b
8.0xlO'b
1.4XKT5
6.2xlQ-y
3.2xlQ-y
1.6xlQ-y
2.3xlO'b
2007 and Later
Emission Rate (g/mi)
1.6xlO'b
3.4x10-'
5.5x10-'
6.5x10-'
6.2x1 Q-y
3.2xlQ-y
1.6xlQ-y
2.3xlO-b
3.1.4. Dioxins
MOVES estimates emissions for 17 dioxin and furan congeners (Table 16). The
emissions are estimated using mg/mile emission factors. These emission factors were obtained
from EPA's dioxin assessment.2
18
-------
Table 16. Dioxin/furan emission factors for diesel vehicles and trucks.
Pollutant
2,3,7,8-TCDD TEQ
1,2,3,7,8-Pentachlorodibenzo-p-Dioxin
1,2,3, 4,7, 8-Hexachlorodibenzo-p-Dioxin
1,2,3,6,7,8-Hexachlorodibenzo-p-Dioxin
1,2,3, 7,8, 9-Hexachlorodibenzo-p-Dioxin
1,2,3,4,6,7,8-Heptachlorodibenzo-p-
Dioxin
Octachlorodibenzo-p-dioxin
2,3,7,8-Tetrachlorodibenzofuran
1,2,3,7,8-Pentachlorodibenzofuran
2,3 ,4, 7, 8-Pentachlorodib enzofuran
1,2,3, 4,7, 8-Hexachlorodibenzofuran
1,2,3,6,7,8-Hexachlorodibenzofuran
1,2,3, 7,8, 9-Hexachlorodibenzofuran
2,3,4,6,7,8-Hexachlorodibenzofuran
1,2,3,4,6,7,8-Heptachlorodibenzofuran
1,2,3,4,7,8,9-Heptachlorodibenzofuran
Octachl orodib enzofuran
Mg/mi
5.52E-08
4.67E-08
6.57E-08
1.29E-08
2.37E-07
1.55E-06
7.14E-06
1.39E-07
5.55E-08
1.23E-07
2.08E-07
9.47E-08
5.51E-08
1.37E-07
4.30E-07
4.89E-08
4.91E-07
3.2. Evaporative
MOVES estimates evaporative emissions associated with spillage for diesel vehicles.
Since there are no speciated emissions of diesel spillage emissions, we developed toxic to VOC
ratios based on a diesel headspace profile, profile number 4547 from the SPECIATE database.
These ratios are provided in Table 17.
Table 17. Toxic to VOC ratios for diesel spillage emissions.
Pollutant
2,2,4-Trimethylpentane
Ethyl Benzene
Hexane
Toluene
Xylene
Benzene
Toxic/VOC
0.00974
0.00324
0.01076
0.01419
0.01222
0.00410
19
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1 U. S. EPA. 2010. Motor Vehicle Emission Simulator (MOVES) 2010: User Guide. Report
No. EPA-420-B-09-041. Available at http://www.epa.gov/otaq/models/moves/420b09041 .pdf.
2 U. S. EPA. 2004. MOBILE6 Vehicle Emissions Model. Available at
http ://www. epa.gov/otaq/m6. htm.
3 Michaels, H.; Brzezinski, D.; Cook, R. EPA's National Mobile Inventory Model (NMEVI), A
Consolidated Emissions Modeling System for MOBILE6 and NONROAD; EPA-420-R-05-003,
U. S. Environmental Protection Agency, Office of Transportation and Air Quality, Assessment
and Standards Division, Ann Arbor, MI, 2005. (Available at
http://www.epa.gov/otaq/nmim.htm).
4U. S. EPA. 1993. Final Regulatory Impact Analysis for Reformulated Gasoline. December 13,
1993. Available at http://www.epa.gov/otaq/regs/fuels/rfg/
5 Michaels, H., Brzezinski, D., Cook, R. 2005. EPA's National Mobile Inventory Model
(NMEVI), A Consolidated Emissions Modeling System for MOBILE6 and NONROAD. U. S.
EPA, Office of Transportation and Air Quality, Assessment and Standards Division, Ann Arbor,
MI, March 2005; Report No. EPA-420-R-05-003. Available at
http ://www. epa. gov/otaq/nmim. htm.
6Sierra Research, 2010. Development of Emission Rates for the MOVES Model. Prepared for
the U. S. Environmental Protection Agency by Sierra Research, Sacramento, CA, July 2, 2010.
Sierra Research Report No. SR2010-07-01.
7 U. S. EPA. 2009. Exhaust Emission Profiles for EPA SPECIATE Database: Energy Policy Act
(EPAct) Low-Level Ethanol Fuel Blends and Tier 2 Light-Duty Vehicles. Assessment and
Standards Division, Office of Transportation and Air Quality. Report No. EPA-420-R-09-002.
8 Michaels, H., Brzezinski, D., Cook, R. 2005. EPA's National Mobile Inventory Model
(NMEVI), A Consolidated Emissions Modeling System for MOBILE6 and NONROAD. U. S.
EPA, Office of Transportation and Air Quality, Assessment and Standards Division, Ann Arbor,
MI, March 2005; Report No. EPA-420-R-05-003. Available at
http ://www. epa. gov/otaq/nmim. htm.
9 Watson, J. D., E. Fujita, J. C. Chow, and B. Zielinska. 1998. Northern Front Range Air Quality
Study. Desert Research Institute. See Table 4.4-4, page 4-41.
10 U. S. EPA, 2001. Revised Methodology and Emission Factors for Estimating Mobile Source
PAH Emissions in the National Toxics Inventory. Memorandum from Rich Cook and Joseph
Somers, Office of Transportation and Air Quality, to Laurel Driver, Office of Air Quality
Planning and Standards, June 11, 2001.
20
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uSierra Research, 2010. Development of Emission Rates for the MOVES Model. Prepared for
the U. S. Environmental Protection Agency by Sierra Research, Sacramento, CA, July 2, 2010.
Sierra Research Report No. SR2010-07-01.
12U.S. EPA, 2009. SPECIATE 4.2 Speciation Database Development Documentation, Office of
Research and Development. Report No. EPA/600-R-09/038, June 2009.
13 Schauer, J.J., M.J. Kleeman, G.R. Cass, and B.R.T. Simoneit. Measurement of Emissions
from Air Pollution Sources, 2. C1-C30 Organic Compounds from Medium Duty Diesel Trucks.
Environmental Science and Technology, vol. 33, no. 10, pp. 1578-1587, 1999.
14 Norbeck, J. M., T. D. Durbin, and T. J. Truex. 1998. Measurement of Primary Particulate
Matter Emissions from Light Duty Motor Vehicles. Prepared by College of Engineering, Center
for Environmental Research and Technology, University of California, for Coordinating
Research Council and South Coast Air Quality Management District. See Tables 16 and 17.
15 U. S. EPA. 2009. Development of Emission Rates for Light-Duty Vehicles in the Motor
Vehicle Emissions Simulator: Draft Report. Assessment and Standards Division, Office of
Transportation and Air Quality, Ann Arbor, MI, August 2009. Report No. EPA-420-P-09-002.
http://www.epa.gov/otaq/models/moves/techdocs/420p09002.pdf
16 Ball, James C. Emission Rates and Elemental Composition of Particles Collected From 1995
Ford Vehicles Using the Urban Dynamometer Driving Schedule, the Highway Fuel Economy
Test, and the USO6 Driving Cycle. 97FL-376. Society of Automotive Engineers, Inc. 1997.
17 Taylor, M. Memorandum: Revised HAP Emission Factors for Stationary Combustion
Turbines, Prepared by Alpha-Gamma Technologies, Inc for Sims Roy, EPA OAQPS ESD
Combustion Group. August, 2003.Docket ID: OAR-2002-0060-0649.
Access via http://www.regulations.gov
18 Schauer, J. J., Lough, G. C., Shafer M. M., Christensen W. F., Arndt, M. F., DeMinter, J.T.,
Park, J-S. 2006, Characterization of Metals Emitted from Motor Vehicles.
Health Effects Institute Research Report Number 133, available at:
http: //pub s. healtheffects. org/
19 U. S. EPA. Draft Final Assessment: Exposure and Human Health Reassessment of 2,3,7,8-
Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. Volume 2: Sources of Dioxin-
Like Compounds in the United States. Office of Research and Development, National Center for
Environmental Assessment, Washington, D.C. Report No. EPA/600/P-00/001Bb, September
2000.
20C.E. Lindhjem, Emission Profiles for EPA SPECIATE Database, EPA Contract No. EP-C-06-
094, Work Assignment No. 1-7, ENVIRON International Corporation, January 31, 2008.
91
Southwest Research Institute. 2009. Evaporative Emissions Breakdown Including Permeation
Effects and Diurnal Emissions on Aging Enhanced Evaporative Emissions Certified Vehicles
21
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(CRC E-77-2b). Prepared by Harold M. Haskew and Thomas F. Liberty, Harold Haskew and
Associates, Inc.; submitted to U. S. EPA, December, 2009. Available at www.crcao.org.
22 Haskew, H. M., Liberty, T. F., and McClement, D. 2004. Fuel Permeation from Automotive
Systems. Prepared for the Coordinating Research Council by Harold Haskew and Associates
and Automotive Testing Laboratories, Inc. September 2004. CRC Project No. E-65.
http://www.crcao.com.
23
24 Hsu ,Y., and Mullen, M. 2007. Compilation of Diesel Emissions Speciation Data. Prepared
by E. H. Pechan and Associates for the Coordinating Research Council. CRC Contract No. E-
75, October, 2007. Available at www.crcao.org.
25Khalek, I, Rougher, T., and Merritt, P. M. 2009. Phase 1 of the Advanced Collaborative
Emissions Study. Prepared by Southwest Research Institute for the Coordinating Research
Council and the Health Effects Institute, June 2009. Available at www.crcao.org.
26 U. S. EPA. Draft Final Assessment: Exposure and Human Health Reassessment of 2,3,7,8-
Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. Volume 2: Sources of Dioxin-
Like Compounds in the United States. Office of Research and Development, National Center for
Environmental Assessment, Washington, D.C. Report No. EPA/600/P-00/001Bb, September
2000.
22
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Appendix A: Documentation of Development of Motor Vehicle
Emission Factors for Mercury
-------
Calculation of Mercury Emission Factors from Vehicle Tests
In 2005, the National Exposure Research Laboratory (NERL) of the EPA collected
mercury samples in the raw exhaust from 14 light-duty gasoline vehicles and two heavy-duty
diesel vehicles. The work plan for this project includes details of the methods used that are not
reproduced here including quality assurance and quality control for Hg collection and analysis.
This information can be obtained from EPA upon request. Briefly, mercury and regulated
pollutant data were collected during two sets of three consecutive LA92 drive cycles for each
vehicle. The morning set of LA92 cycles began with one 'cold start' and the afternoon set of
three LA92 cycles began with a 'hot start'. The intake air was prefiltered through charcoal to
greatly reduce background mercury concentrations going into the vehicle intake. Separate
sampling lines were used for gas and particle mercury species. Samples analyzed for mercury
were drawn from raw exhaust at a constant flow rate and fixed dilution. Carbon dioxide
measurements were also taken in the exhaust stream where mercury samples were collected.
Mercury samples were collected in raw exhaust since previous data suggested that
mercury levels might be sufficiently low to challenge mercury detection limits. This sampling
method imposed a challenge in calculating emission factors since it assumes that the exhaust
flow rate from the vehicle is constant. Calculation of exhaust flow and how this was applied to
the development of mercury emission factors is described below.
Evaporative losses of mercury from motor vehicles and loss of mercury during refueling
were not measured and therefore not included in the National Emissions Inventory. The
emission of mercury from these evaporative sources is expected to be small compared with the
combustion exhaust emissions of mercury from mobile sources.
A description of the vehicles tested for which data were used in developing emission
factors is provided in Table 1. The data collected from these vehicles in diluted exhaust in the
constant volume sampler (CVS) included total hydrocarbon (THC), carbon dioxide (CO2),
nitrogen oxides (NOX), methane (CH4), and carbon monoxide (CO). In raw, undiluted exhaust,
data collected included elemental and total gas-phase mercury, paniculate mercury and CC>2.
Gas-phase mercury was also measured in the intake air. Total air flow and standard temperature
and pressure-corrected flows for all the sampling systems were measured. The data streams had
different reporting frequencies, all due to the nature of the instrumentation. The dilute
measurement of the standard emission gases (THC, CO2, NOX, CH4, and CO), CVS flows, and
vehicle speed were reported at 1 Hertz. The gas-phase mercury samples were analyzed at 2.5
minute intervals and particle-phase mercury samples were collected cumulatively for the
duration of three consecutive LA92 cycles. Gas-phase elemental mercury in the engine intake
air was measured in 5 minute intervals.
A-2
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Table 1. Vehicles tested for Mercury Emissions
Model
Year
2005
2005
2003
2002
2001
2001
2000
2000
1999
1999
1998
1994
1992
1991
1987
1984
Make
MERCURY
FORD
SATURN
HONDA
HONDA
CHRYSLER
CHEVROLET
JEEP
FORD
FORD
HONDA
CHEVROLET
CHEVROLET
HONDA
CHRYSLER
FORD
Model
GRAND MARQUIS
LS
MUSTANG
CONVERTIBLE
L200
ACCORD EX
ACCORD EX
PT CRUISER
SUBURBAN
CHEROKEE SPORT
F250 XLT
F250 XLT SD
CIVIC DX
SILVERADO
S10 BLAZER
ACCORD EX
FIFTH AVENUE
F150 PICKUP
Fuel Type
Gasoline
Gasoline
Gasoline
Gasoline
Gasoline
Gasoline
Gasoline
Gasoline
Diesel
Diesel
Gasoline
Gasoline
Gasoline
Gasoline
Gasoline
Gasoline
Odometer
9,953
5,424
29,667
51,824
88,611
54,010
39,787
48,468
113,897
109,429
204,983
129,521
162,249
143,289
72,573
36,727
Cylinders
8
6
4
4
4
4
8
6
8
8
4
8
6
4
8
8
Displacement
4.6
4
2.2
2.3
2.3
2.4
6
4
7.3
7.3
1.6
5.7
4.3
2.2
5.2
5.8
Exhaust flow was integrated at the same reporting frequency as the mercury exhaust
values for a particular test and then used to calculate total, elemental, and reactive gas-phase
mercury mass emissions. The intake air mercury values were typically collected at half the
frequency of the mercury exhaust values. There is precedent in accepting background values
measurements at less frequent intervals and using them to correct exhaust measured values that
are reported at higher frequencies. The particulate matter measurements were filter-based, test-
level measurements and were reported in that manner.
Calculation of Emission Rates
The data for regulated pollutants and mercury were time-aligned; however, emissions
data were not attributed to vehicle specific power as the data are not to be used in modal
emissions modeling at this time. Emission rates were calculated separately for elemental gas-
phase mercury, reactive gas-phase mercury and particulate mercury. Elemental gas-phase
mercury in the exhaust was corrected for the intake air concentration of elemental mercury. To
estimate the gas-phase mercury concentration in dilute exhaust from the measured mercury in
raw exhaust, the dilution factor was applied. For light-duty gasoline vehicles, the dilution factor
equation found in 40 CFR 90.426 (d) was used:
Dilution factor = 13.4 / ([CO2%] + ([THC, ppm] + [CO, ppm])* 0.0001)
Exhaust flow = (CVS flow / dilution factor)
A-3
-------
Exhaust flow calculation was initiated when the analytical equipment indicated that the
dilute exhaust CC>2 concentration was greater than the background CC>2 concentration.
To calculate exhaust flow for the diesel vehicles, the dilution factor was calculated by
simply dividing CC>2 in the raw exhaust by CC>2 in the CVS. This method was used because
diesel engines operate across a very wide range of fuel to air mixtures and the CFR method
described above was not appropriate.
Determination of Reactive Gas Mercury Mass in Exhaust
Reactive gas mercury (ROM) was calculated by subtracting elemental gas-phase mercury
measurements from total gas-phase mercury measurements. RGM values were typically small
and therefore influenced by the variability in the elemental mercury measurements. Negative
RGM values for a given measurement period were observed. Values for which there was not a
positive RGM measurement were treated as non-detects and were nulled in the aggregation of
RGM values for the test. The measurement uncertainty for gas-phase elemental mercury was
estimated from quantitative recovery of injections of known amounts of mercury into the
sampling system. The uncertainty in measuring elemental mercury was applied to the total gas-
phase and elemental gas-phase measurements to determine when the RGM value was above the
measurement uncertainty. Values within the measurement uncertainty were not included in the
emission factor calculation.
Calculating Weighted Emission Test Results
Highway vehicle tests used the California Air Resource Board's LA92, a more aggressive
chassis dynamometer test similar in concept to the Federal Federal Test Procedure's (FTP)
HDDS or LA4. Like the FTP, the LA92 includes a cold start, a hot start, and a hot stabilized
phase using identical drive schedules for the starts and for the stabilized phase. It was, therefore,
considered appropriate to follow the precedent of calculating a weighted emission factor
(representing cold start and hot start driving) for each vehicle in the same manner as the FTP,
using the equation below for each test (a test consisting of all six LA92 cycles performed on each
vehicle).
We summed the gas-phase mercury mass emissions for the first phase (300 seconds) of
the morning test and last phase (1,135 seconds) of the individual LA92 drive schedules for all the
tests (e.g., 'hot stabilized emissions'), divided by the total distance covered in these phases and
multiplied by 0.43. We also summed the sum of the mass gas-phase mercury emissions of the
first phase of the afternoon test and last phase (1,135 seconds) of all the tests, divided by the total
distance covered in these phases and multiplied by 0.57. The two terms were summed to
calculate a test level emission rate for each of the gasoline powered vehicles.
Equation used to calculate test-level emission rates:
Grams/mile emission factor = 0.43 *(C + R)/( Cm + Rm) + 0.57*(H+R)/( Hm + Rm)
Where:
A-4
-------
C = mercury mass collected in the first 300 seconds of the first morning
test ('cold start')
Cm = distance covered by the cold start
R = mercury mass collected in the last 1,135 seconds of all six cycles of
the LA92 ('hot stabilized')
Rm= cumulative distance covered by all six cycles of the LA92 ('hot
stabilized ')
H = mercury mass collected in the first 300 seconds of the first afternoon
test ('hot start')
Hm = distance covered by the hot start
It should be noted that the 'hot start' in the afternoon typically occurred after the vehicle
had been off for at least 1 hour, making this start closer to a 'cold start' than 'hot start'. Since
the true cold start emissions were slightly higher than hot start emissions, it is expected that this
approach would bias the emission factors high by a small amount.
Particulate mercury emissions could not be apportioned into modes of operation in
similar manner because filters were collected across all three LA92 cycles and could not be
parsed into the three phases. A test-level emission rate was calculated by multiplying the
morning particulate mercury emission rate by 0.43 and the afternoon particulate mercury
emission rate by 0.57 and adding the two values together.
The average of emission factors across vehicles was calculated for each form of mercury
and is reported in Table 2. A simple average was used since the data did not suggest that
mercury concentrations varied by vehicle age, mileage, displacement or other factors.
Mercury emission factors for on-road diesel engines were obtained from the first 715
seconds of the morning and afternoon tests on the Ford F250 XLT SD; data from the second
diesel vehicle could not be used. The first 715 seconds is approximately half of the first of the
three LA92 drive cycles that made up a single test. The truncation of the test was due to sample
flow problems in the mercury sampling manifold due to particulate matter restricting flow across
the particulate matter filters. Graphical analysis of exhaust flow indicated that at they appeared
nominal during the first LA92 cycle. It was decided that only using data collected before 715
seconds into both tests provided the most reliable data.
A-5
-------
Table 2. Mercury Emission Factors from Mobile Sources
Source Category
Gasoline motor
vehicles
Diesel motor
vehicles
Gasoline nonroad
engines
Diesel nonroad
engines
Pollutant
Elemental gas-
phase mercury
Reactive gas-
phase mercury
Particulate
mercury
Elemental gas-
phase mercury
Reactive gas-
phase mercury
Particulate
mercury
Elemental gas-
phase mercury
Reactive gas-
phase mercury
Particulate
mercury
Elemental gas-
phase mercury
Reactive gas-
phase mercury
Particulate
mercury
Pollutant
Code
200
201
202
200
201
202
200
201
202
200
201
202
Emission
Factor
1.1E-07
9.9E-09
4.0E-10
6.2E-09
3.2E-09
1.6E-09
1.8E-06
1.7E-07
6.9E-09
1.2E-07
6.2E-08
3.2E-08
Units
grams/mile
grams/mile
grams/mile
grams/mile
grams/mile
grams/mile
grams/gallon
grams/gallon
grams/gallon
grams/gallon
grams/gallon
grams/gallon
A-6
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