EPA-450/3-78-021
April 1978
A LEAD EMISSION FACTOR
FOR REENTRAINED DUST
FROM A PAVED ROADWAY
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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EPA-450/3-78-021
A LEAD EMISSION FACTOR
FOR REENTRAINED DUST
FROM A PAVED ROADWAY
by
Christine M. Maxwell and Daniel W. Nelson
Midwest Research Institute
425 Volker Boulevard
Kansas City, MO 64110
Contract No. 68-02-2609
Task No. 2
EPA Project Officer: Charles C. Masser
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
April 1978
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This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited number of readers. Copies are
available free of charge to Federal employees, current contractors and
grantees, and nonprofit organizations - in limited quantities - from
the Library Services Office (MD-35), U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27711; or, for a fee, from the
National Technical Information Service, 5285 Port Royal Road, Springfield,
Virginia 22161.
This report was furnished to the Environmental Protection Agency by
Midwest Research Institute, 425 Volker Boulevard, Kansas City, Missouri 64110.
The contents of this report are reproduced herein as received from Midwest
Research Institute. The opinions, findings, and conclusions expressed are
those of the author and not necessarily those of the Environmental Protection
Agency. Mention of company or product names is not to be considered as an
endorsement by the Environmental Protection Agency.
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PREFACE
This report was prepared for the Environmental Protection Agency under
Contract No. 68-02-2609, Task Assignment No. 2. Mr. Charles Masser, Office
of Air Quality Planning and Standards, was the requester of this work.
The work was performed in the Environmental and Materials Sciences Divi-
sion of Midwest Research Institute under the supervision of Dr. Chatten
Cowherd, Jr., Head, Air Quality Assessment Section. Mrs. Christine Maxwell,
Principal Investigator, and Mr. Daniel Nelson were the authors of this report.
Other MRI technical staff contributing to this project were Mr. Russel Bohn
and Mrs. Carol Green.
Approved for:
MIDWEST RESEARCH INSTITUTE
M. P. Schrag, Deputy Director
Environmental and Materials
Sciences Division
111
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SUMMARY
The study reported herein is directed to the development of a lead emis-
sion factor for reentrained dust from paved roadways. With the impending
adoption of an ambient air quality standard for lead, emission factors for
major sources will be needed to pinpoint areas where emission control is re-
quired.
The results of this study indicate that the lead emission factor for
reentrained dust is approximately 0.03 g per vehicle mile for the 1975-1976
sampling period. That approximation was calculated using the data from this
study and from other investigations:
Lead emission factor for 1975-1976
(g/vehicle mile)
Total Dust reentrainment
(based on field (based on
measurements) MRI calculations)
Range Average Range Average
MRI 0.03 to 0.11 0.06 0.01 to 0.06 0.03
PEDCo 0.005 to 0.319 0.07 0.03
Average 0.065 0.03
It is apparent that decreasing the lead content in gasoline will not only
decrease the amount of airborne lead emitted from vehicle exhaust, but also
will decrease the amount of lead-containing dust reentrained from paved road-
ways. With the reduction of lead in leaded gasoline and the continued intro-
duction of catalyst equipped vehicles into the vehicle distribution, the lead
emission factor for reentrained dust is expected to drop below 0.01 by 1980.
Analysis of airborne particulate samples for lead particle size distribu-
tion shows that the mass median diameter for particulate lead is about 1 urn as
compared to a mass median diameter of about 5 um for total airborne particu-
late.
This report documents the methodology used to develop the lead emission
factor for reentrained dust. Samples of airborne particulate from two paved
roadways in the Kansas City area, obtained by Midwest Research Institute under
iv
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the Environmental Protection Agency Contract No. 68-02-1403, were analyzed for
lead content. The results of these analyses were used to derive the combined
particulate lead emission factor for vehicle exhaust and reentrained dust. A
separate calculation procedure was used to divide the combined particulate
emission factor into the emission factors for vehicle exhaust and reentrained
dust.
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CONTENTS
Preface iii
Summary iv
Figures vii
Tables viil
1.0 - Introduction 1
1.1 - Background 1
1.2 - Objective 1
2.0 - Reentrained Dust Sampling Methodology 3
2.1 - Field Test Locations 3
2.2 - Field Measurement Methodology 3
3.0 - Analysis of Selected Samples for Lead 13
4.0 - Development of Total Lead Emission Factor 19
4.1 - Uncorrected Test Results 19
4.2 - Isokinetic Correction 19
4.3 - Particle Size Adjustment 23
4.4 - Total Lead Emission Factor 25
5.0 - Emission Factor Contributions 26
5.1 - MRI Sampling Site Characteristics 26
5.2 - Lead from Vehicle Exhaust 26
5.3 - Lead from Dust Reentrainment 30
5.4 - MRI Results 32
6.0 - Comparison of Results 34
6.1 - PEDCo Study 34
6.2 - GCA Study 37
6.3 - Summary of Results 37
References 39
Glossary 40
Appendix - Example Calculation of Lead Emission Factor (Run 5) ... 42
vi
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FIGURES
Number Page
1 MRI Exposure Profiler 7
2 Location of Sampling Instruments at 37th Street Site--
South Wind 8
3 Location of Sampling Instruments at 37th Street Site--
North Wind 9
4 Location of Sampling Instruments at Fairfax Trafficway--
Side View 10
5 Location of Sampling Instruments at Fairfax Trafficway--
Overhead View 11
6
6 Distribution of Street Dust - 37th Street 17
7 Distribution of Street Dust - Fairfax Trafficway 18
8 Percentage of Burned Lead Exhausted Versus Vehicle
Cruise Speed 29
9 Comparison of Lead Concentrations at Various Sampling
Heights 36
vii
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TABLES
Number Page
1 Test Site Characteristics 4
2 Field Measurements--Paved Roads 6
3 Lead Analysis of Reentrained Dust (37th Street) 14
4 Lead Analysis of Reentrained Dust (Fairfax Trafficway) . . 15
5 Emissions Test Parameters 20
6 Suspended Particulate Concentration and Exposure
Measurements 21
7 Lead Concentration and Exposure Measurements 22
8 Particle Size Data 24
9 Measured Total Particulate Lead Emission Factors 25
10 Projected Vehicle Exhaust Lead Emission Factors
(Composite Operation) 27
11 Vehicle Exhaust Lead Emission Factors (Constant
Cruise Speeds) 28
12 Summary of Vehicle Exhaust Lead Emission Factors 31
13 Summary of Particulate Lead Emission Factors 33
14 Comparison of Lead Results 35
viii
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SECTION 1.0
INTRODUCTION
This report presents the results of a program conducted by Midwest Research
Institute (MRI) to characterize the amount of lead in road dust resuspended by
the operation of vehicles on paved roadways. In this section, the background
of the problem is reviewed and the study objective outlined.
1.1 BACKGROUND
The U.S. Environmental Protection Agency (EPA) has been given the task of
developing an ambient air quality standard for lead. With the proposed air
quality standard to be announced in the near future, the states will be re-
quired to start development of State Implementation Plans (SIP). An integral
part of the SIP will be the lead emission inventory which will pinpoint areas
where emission control is needed. One potentially significant source of air-
borne lead consists of lead in road dust resuspended by the operation of ve-
hicles on a paved roadway.
1.2 OBJECTIVE
The objective of this investigation was to determine a lead emission fac-
tor for reentrained dust from paved roadways. To accomplish this objective,
three major tasks were carried out, as summarized below:
Task 1 - Review Related Reports - Two specific reports were reviewed for
useful information for the development of a lead emission factor for re-
entrained dust from paved roads. The reports were: "Lead Analysis for
Kansas City and Cincinnati," (EPA Contract No. 68-02-2515)!/ and "Particulate
Study of the Philadelphia Air Quality Control Region," (EPA Contract No. 68-
02-2345).I/
Task 2 - Analyze Selected Dust Samples for Lead - This task consisted of
analysis for lead in samples of reentrained dust (i.e., airborne particulate)
obtained by MRI at the 37th Street and Fairfax Trafficway sites in the Kansas
City metropolitan area under EPA Contract No. 68-02-1403. Sample collection
media from high-volume samplers were analyzed for lead. These samples in-
cluded (a) high-volume filters, (b) impactor substrates, and (c) impactor
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preseparator washes. In order to calculate lead emission factors, samples of
street dust loadings were obtained as part of this study, from the above sites
and analyzed for lead.
Task 3 - Develop Emission Factor - Information gathered in Tasks 1 and 2
above, was compiled and a lead emission factor for reentrained dust from a
paved roadway was developed. The methodology used is completely documented
in this report. Since the vehicle mix is changing due to the introduction of
the catalytic converter, the methodology can be expanded to account for de-
creases in lead content of gasoline for noncatalyst vehicles, and phase-in of
catalyst vehicles.
The following sections of this report present (a) a description of the
reentrained dust sampling methodology including field test locations and
measurement techniques, (b) a summary of the lead analysis results, (c) the
methodology for the development of a lead emission factor, (d) a summary
of results and (e) comparisons with other studies.
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SECTION 2.0
REENTRAINED DUST SAMPLING METHODOLOGY
2.1 FIELD TEST LOCATIONS
Q/
Under EPA Contract No. 68-02-1403, Tasks 7 and 25,- field testing was
conducted by MRI at several representative paved and unpaved road sites in
the Kansas City area. Two of the paved road sites were selected for quantifi-
cation of lead in reentrained dust: 37th Street and Fairfax Trafficway.
Both sites are four-lane arterial streets in areas where attainment of parti-
culate standards has been a problem. In addition, both sites have high traf-
fic volume especially during shift changes at nearby automotive assembly
plants. Table 1 summarizes the characteristics of each test site.
The 37th Street test roadway passes through a center-city residential
neighborhood interspersed with light-to-medium industrial activity. The test
pavement along 37th Street is asphalt and bordered by an unpaved parking area.
Medium industry surrounds the Fairfax Trafficway test site. This road-
way is also surfaced with asphalt. Unpaved parking lots are located in sev-
eral nearby areas. The traffic volume is heavy in both directions for the
periods 6 to 9 AM and 2 to 4 PM. (Approximately 700 vehicles per hour were
recorded for the 6 to 9 AM period and 1,400 vehicles per hour were recorded
for the 2 to 4 PM period.)
2.2 FIELD MEASUREMENT METHODOLOGY
Field testing of airborne particulate emissions from paved roads was con-
ducted at the 37th Street site in September and October 1975, and at the Fair-
fax Trafficway site in March 1976, under EPA Contract No. 68-02-1403.
To the extent possible, emission sampling was restricted to periods with
moderate crosswinds (approximately 5 to 10 mph) and 3 or more days after sig-
nificant rainfall (accumulation exceeding 0.5 in.). The ideal wind direction
for exposure profiling is perpendicular to the road such that airborne particles
flow directly away from the traffic and toward the sampling intakes. The ideal
wind speed for the profiler is approximately 10 mph. This is in the middle
of the range in which the profiler can be adjusted for isokinetic sampling.
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TABLE I. TEST SITE CHARACTERISTICS
Site
Location
Land use
Average daily traffic
Street characteristics
Orientation
Surface type
Surface condition
Curbed
Ventilation
Air sampling station
Operating agency
37th Street
Leeds Fire Station No. 26
6402 East 37th Street
Kansas City, Missouri
Residential (medium in-
dustry nearby)
7,870
East-west
Asphalt
Poorly maintained, cracked
Yes
Kansas City, Missouri
Fairfax Trafficway
Fire Station No. IS
5200 Fairfax
Kansas City, Kansas
Medium industry
8,360
North-south
Asphalt
Well maintained, smooth
Yes
Kansas City, Kansas-Wyandotte
County Health Department
Geometric mean
TSP (ug/m3)
1972
1973
1974
MRI runs
86
101
87
3, 5, 6
96
86
75
15
to 16
a/ Partial rcnrrlctlon caused by predominance of two- to three-story buildings In immedi-
ate area. Fairfax Trafficway area only restricted on west side of street.
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Isokinetic sampling is achieved by adjusting the profiler flow rate such that
when dividing the flow rate by the intake area, the result is equal to the
mean wind speed. The lapse of several days after significant rainfall allows
the particulate loading on the road surface to return to the equilibrium level.
Table 2 specifies the kinds and frequencies of field measurements that
were conducted during each run. "Composite" samples denote a set of single
samples taken from several locations in the area; "integrated" samples are
those taken at one location for the duration of the run.
2.2.1 Sampling Equipment
The primary tool for quantification of emission rate was the MRI exposure
profiler which was developed under EPA Contract No. 68-02-0619.^ The pro-
filer has undergone design and operational changes since its original develop-
ment. The profiler used for this study consists of a portable tower (4 meters
in height) with four sampling heads (see Figure 1). The sampling heads were
equipped with individual flow controllers to adjust to isokinetic conditions.
New directional exposure intakes were added that automatically separate out
the settleable particulates. Other mechanical hardware and flow indicators
were attached to increase the ease of operation.
In addition to the profiler, high-volume samplers were set up to measure
upwind and downwind suspended particulate concentrations and a cascade impactor
was used for particle sizing. These samplers measured concentrations at breath-
ing height (2 m above the ground). The impactor unit was equipped with a
Sierra cyclone preseparator to remove coarse particles which otherwise would
tend to bounce off of the glass fiber impaction substrates, causing fine par-
ticle measurement bias.
Figures 2 through 5 show the locations of sampling instruments at the
37th Street and Fairfax Trafficway sites. Distances from curbing are speci-
fied. For comparative purposes, the profiler, high-volume samplers and cas-
cade impactor were placed approximately the same distance from the curb.
By means of a pivotal bearing and wind vane, the cyclone preseparator in-
take was continually directed into the wind. By having the flow controller
set for 40 cfm and using a 3 in. diameter cyclone intake, the unit was set
to isokinetic conditions for approximately a 10 mph wind.
Other site parameters that were mechanically recorded during each test
included: wind speed, wind direction and vehicular traffic counts.
2.2.2 Sample Handling and Particulate Analysis
At the end of each run, the collected samples were carefully transferred
to protective containers within the MRI instrument van to prevent dust losses.
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TABLE 2. FIELD MEASUREMENTS --PAVED ROADS
Test Parameter
Units
Sampling Mode
Measurement Method
1. Meteorology
a. Wind speed
b. Wind direction
c. Cloud cover
d. Temperature
e. Relative humidity
2. Road Surface
a. Pavement type
b. Surface condition
c. Dust loading
d. Dust texture
3. Vehicular Traffic
a. Mix
b. Count
mph
Degree
7.
g/m2
% silt
Continuous}
Continuous)
Single
Single
Single
Recording instrument at "background"
station; sensors at reference height
Visual observation
Sling psychrometer
Sling psychrometer
Composite Observation (photographs)
Composite Observation
Multiple Dry vacuuming
Multiple Dry sieving
Multiple Observation (car, truck, number of
axles, etc.)
Cumulative Automatic counters
4. Suspended Dust
a. Exposure (versus height) mg/cm2 Integrated
b. Mass size distribution ym Integrated
c. Downwind concentration yg/m3 Integrated
d. Background concentration \jg/to3 Integrated
e. Duration of sampling min Cumulative
Isokinetic high-volume filtration (MRI
method)
High-volume cascade impaction
High-volume filtration (EPA method!/)
High-volume filtration (EPA method!/)
Timing
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Figure 1. MRI Exposure Profiler
7
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KEY
HI -VOL
SAMPLER
rf.
N CASCADE
IMPACTOR
^n n WIND
~~ v U
INSTRUMENT
DUSTFALL
SAMPLER
<£>
EXPOSURE
PROFILER
00
WIND DIRECTION
x
o i
GJ
1 2
4
(-
h-
•I9.SM-
•I4M-
Figure 2. Location of Sampling Instruments at 37th Street Site—South Wind
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KEY
/\
HI-VOL
SAMPLER
HI-VOL
N CASCADE
IMPACTOR
WIND
INSTRUMENT
DUSTFALL
SAMPLER
EXPOSURE
PROFILER
5 3
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KEY t£,
12
II
10
a
NTAKE HEIGHT (M)
* (* » •» 0 «
3
2
S '
r-
-
y\
w
HI -VOL f~l HI- VOL
SAMPLER t-J CASCADE
M IMPACTOR
«*.
c£
^ Q n WIND Q DUSTFALL
^ v Ll INSTRUMENT SAMPLER «*
WIND DIRECTION | |^>
-
s\
k?
h
h
t
-5X1
id
id
0^
n
*— 7.3 M-
*CHJ
-
-H
^
^
i
EXPOSURE
PROFILER
i
30 y ., _. ..
/s
5?
.i
Figure 4. Location of Sampling Instruments at
Fairfax Trafficway—Side View
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N
Parallel Parking
SUNSHINE
Parallel Parking
WIND DIRECTION
Q HI-VOL SAMPLER
0 EXPOSURE PROFILER
O CASCADE IMPACTOR
•Q WIND INSTRUMENT
i
5.OM-*
-13.9 M-
3
u_
<
! I
4.OM
'•a
-7.3M-
4.0u -;
M
4-4.4 M-»Q*-
•30M-
Figure 5. Location of Sampling Instruments at
Fairfax Trafficway—Overhead View
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High-volume filters (from the MRI exposure profiler and from standard high-
volume units) and impaction substrates were folded and placed in individual
envelopes. Particulate that collected on the interior surfaces of each ex-
posure profiler intake and from the cyclone preseparator was rinsed with dis-
tilled water into separate glass jars.
Field testing samples were returned to MRI and analyzed in the laboratory.
All filter types were conditioned in a controlled temperature and humidity
room for a period of 24 hr before weighing. Several blank filters, taken to
the field, were analyzed the same as the sample filters. The sample weights
were corrected for any difference in blank tare weight and blank final weight.
Wash samples from the exposure profiler intakes and cyclone preseparator
were obtained by filtering wash solution through Whatman No. 42 filters which
were folded into a cone. The sample was drawn through the cone using a water
aspirator for vacuum. The washed filters were dried at 110°C before being
conditioned.
After the particulate analysis was completed, all filters were stored for
future use. High-volume filters and impaction substrates were placed in indi-
vidual glycene envelopes. All wash filters were placed in a common container.
12
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SECTION 3.0
ANALYSIS OF SELECTED SAMPLES FOR LEAD
Reentrained road dust samples obtained by MRI under EPA Contract No. 68-
02-1403^7 were analyzed for lead by flame atomic absorption spectroscopy in
MRI's analytical chemistry laboratories. Sample collection media analyzed in-
cluded: 36 Hi-Vol filters (Type A glass fiber), 25 Sierra impactor substrates,
and 4 filtered intake wash samples (Whatman No. 42). The Sierra cascade im-
pactor has 5 collection stages and a final 8 x 10 in. glass fiber backup filter.
Tables 3 and 4 for 37th Street and Fairfax Trafficway, respectively, sum-
marize the lead content results for each sample. The results, given as "7, Pb,"
are based on 100 times the total micrograms of lead in the sample divided by
the sample (particulate) weight. All calculations were performed using three
significant figures, but the results were rounded to two significant figures.
Less the (<) values are listed as one significant figure. Because of the
possibility of contamination stored in the common container, only a limited
number of wash filters (Run 5) which appeared to be totally intact and uncon-
taminated, were analyzed for lead.
As part of the methodology for the development of the reentrained lead
emission factor, it was necessary to obtain street dust loading
samples. Samples from 37th Street and Fairfax Trafficway test sites were ob-
tained in September 1977. One lane of each street segment was closed off at
a time. Samples were collected for each of the four lane areas and two curb
areas. Road surface areas with high particulate loading (near curbs) were
manually swept with a whisk broom into a dustpan and collected in polyethylene
bags. Subsequently, the entire roadway test surface area was thoroughly
vacuumed with a generator-powered household vacuum cleaner. The vacuumed
material was collected in disposable vacuum cleaner bags, which were secured
and placed into polyethylene bags.
The street loading samples were labelled, stored and analyzed separately.
This was done in case there was a need to look at individual lanes.
A portion of each street surface dust sample was analyzed for lead. Be-
cause of the large quantity of curb sweepings and the time required to do the
analysis, only a small portion was actually analyzed. The lead content of this
13
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TABI£ 3. LEAD ANALYSIS OF REENTRAINED DUST (37TH STREET)
Concentration
Sampling (pg/m3)^
Run Sample height (m) TSP Pb
3 Upwind Hi-Vol 2
Profiler
Profiler
Profiler
Profiler
Downwind
Sierra5-/
1 1
2 2
3 3
4 4
Hi-Vol 2
Stage 1 2 ^
Stage 2 2
Stage 3 2
Stage 4 2
Stage 5 2
Backup 2 '
5 Upwind Hi-Vol
Profiler
Profiler
Profiler
Profiler
Downwind
Sierra5-/
1 Filter 1
Wash 1
2 Filter 2
Wash 2
3 Filter 3
Wash 3
4 4
Hi-Vol 2
Cyclone Wash 2
Stage 1 2 \
Stage 2 2
Stage 3 2
Stage 4 2
Stage 5 2
Backup 2 '
6 Upwind Hi-Vol 2
Profiler
Profiler
Profiler
Profiler
Downwind
Sierra5-^
to 5
a,/ Based on filter
b/ Sierra cutoff
1 1
2 2
3 3
4 4
Hi-Vol 2
•/ Stages 1 2
155 0.46
286 1.00
246 1.33
235 1.11
192 0.76
271 1.82
164^/ 1.72^
130 0.60
283 3.11
223 1.87
187 1.44
140 0.95
281 2.76
207-/ 3.05£/
137 0.56
254 4.06
206 4.50
169 2.70
136 2.98
250 2.20
7. Pb in
filter
catch
0.30
0.35
0.54
0.47
0.40
0.67
0.69
1.5
2.2
2.8
3.3
2.2
0.46
1.1
0.19
0.84
0.23
0.77
0.31
0.68
0.98
0.26
1.4
1.6
2.7
2.6
4.9
2.4
0.41
1.6
2.2
1.6
2.2
0.88
-
catch including background.
diameter for lead density of 5 g/cm : Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
- 2.5 p
- 2.2 p
- 1.2 p
- 0.57 p
- 0.28 p
c_/ Represents total concentration collected on all stages; the most meaning-
ful value for comparison between TSP and lead since cutoff diameters based
on different densities are not the same.
d/ Possible contamination of filters; values are suspect.
14
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TABLE 4. LEAD ANALYSIS OF REENTRAINED DUST (FAIRFAX TRAFFICWAY)
Sampling
Run Sample height (m)
15
16
&/
y
Upwind Hi-Vol
Profiler 1
Profiler 2
Profiler 3
Profiler 4
Downwind Hi-Vol (4.4 m)
Sierra— Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
Backup
Upwind Hi-Vol
Profiler 1
Profiler 2
Profiler 3
Profiler 4
Downwind Hi-Vol (4.4 m)
Sierra^-/ Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
Backup
Based on filter catch including
2
1
2
3
4
2
2 \
2
2 >
2 (
2 )
2 /
2
1
2
3
4
2
2 >t
2
2 >
2 (
2
2 /
background .
Sierra cutoff diameter for lead density of
Concentration
(PR/in3)*/
TSP
268
274
234
212
172
398
234£/
288
342
256
251
208
362
232^
o
5 g/cnr:
Pb
0.72
2.00
1.88
1.21
0.87
2.51
1.60s7
0.63
1.68
1.33
1.13
0.75
1.59
1.15^
Stage 1 -
Stage 2 -
Stage 3 -
Stage 4 -
Stage 5 -
7o Pb in
filter
catch
0.27
0.73
0.80
0.57
0.51
0.63
0.94
1.5
1.6
3.0
2.8
1.4
0.22
0.49
0.52
0.45
0.36
0.44
0.74
0.78
1.2
0.43
1.7
0.99
2.5 u
2.2 u
1.2 11
0.57 u
0.28 u
c_/ Represents total concentration collected on all stages; the most meaning-
ful value for comparison between TSP and lead since cutoff diameters based
on different densities are not the same.
15
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small portion was assumed to be representative. Figures 6 and 7 show the dis-
tribution of street dust loading and corresponding percent lead for the 37th
Street and Fairfax Trafficway sites, respectively. As indicated, the percent
lead in the street dust loading samples ranged from 0.08 to 0.22%. This com-
pares well with other studies which report values in the range of 0.02 to 0.370
16
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N-
Sampling Loading (gm)
Percent Lead
-^
(gm)
t
10'
1
9306 1517
0.
2'
14 0.17
_ 15' •
37th S
89
0.08
treet
147 3264 7465
0.12 0.10 0.17
« IQ'6'1 ».- inizu ^ - ict _ 01
37th Street (Excluding Curb) = 1,650 kg/km
5,830lb/mile
37th Street (Including Curb) = 7,150 kg/km
25,300 Ib/mile
Figure 6. Distribution of Street Dust - 37th Street
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oo
N
Sampling Loading
Percent Lead
'->
0'
9»-»
Fairfax Trafficway
14608 245 75 234 373 8767
0.09 0.10 0.11 0.22 0.20 0.19
— lA'f." M« in* •— 101 • — loun
152 kg/km
539 Ib/mile
3,990 kg/km
14,100 Ib/mile
Fairfax Trafficway (Excluding Curb) =
Fairfax Trdfficway (Including Curb) =
Figure 7. Distribution of Street Dust - Fairfax Trafficway
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SECTION 4.0
DEVELOPMENT OF TOTAL LEAD EMISSION FACTOR
Dust entrainment from a paved road was quantified by measuring the total
passage of airborne dust (after subtraction of background) at some downwind
distance. The calculation procedure for lead exposure and corresponding emis-
sion factor for suspended particulate lead is presented and a sample calculation
is documented in the Appendix. Exposure is defined as the horizontal flux of
airborne dust (mass per time per sampling intake area) integrated over the time
of measurement.
4.1 UNCORRECTED TEST RESULTS
Tables 5 through 7 summarize the particulate emission test parameters for
the 37th Street and Fairfax Trafficway sites.—' Table 5 presents data on the
time of each run, prevailing meteorological conditions, and vehicular traffic
volume. Table 7 gives the results of particulate exposure and concentration
measurements for each run. Table 8 presents the total particulate lead con-
centrations calculated by the methodology given in the Appendix. Background
O
(upwind) lead concentrations are in the range of 0.46 to 0.63 ug/m t which
agree well with other measured ambient concentrations.—'
The following subsections describe in more detail the corrections (a)
to isokinetic sampling conditions and (b) for particles smaller than 30 urn
in diameter.
4.2 ISOKINETIC CORRECTION
It was sometimes necessary to sample at a nonisokinetic flow rate. For
example, to obtain sufficient sample under light wind conditions, the sampling
intake velocity was higher than the mean wind velocity. The following multi-
plicative factors were used to correct both measured exposures and concentra-
tions to corresponding isokinetic values.
19
-------
TABLE 5. EMISSIONS TEST PARAMETERS
ho
O
Time
Run
3
5
6
15
16
Date
9/17/75
9/23/75
10/9/75
3/16/76
3/24/76
Start
1115
1500
1400
1330
1200
Finish
1545
1930
1830
1730
1600
Duration
of exposure
sampling
(min)
270
270
270
240
240
Ambient
Wind
Wind
direction
temperature Speed Direction*' angle to
(°P)
68
78
75
40
66
(mph)
2.0
3.0
2.5
7.1
7.3
C)
140
340
340
290
280
road (°)
40
20
20
20
10
No. of
vehicle
passes
1,880
2,260
2,440
3,791
4,146
No. of
vehicle
passes /hr
418
502
542
948
1,040
a/ Magnetic reading.
-------
TABLE 6. SUSPENDED PARTICUIATE CONCENTRATION AND EXPOSURE MEASUREMENTS
Particulate
concentration (yg/rn^)
at 2 m above
ground
Downwind, including background
Run
3
5
6
15
16
Background*-'
155
130
137
268
288
Profiler*/
Total
295
293
261
336
327
< 30 Mm
257
284
257
292
301
Standard
Hi-Voli/
271
281
250
398
362
Cascade
Impact or—
164
207
230
234
232
Isoklnetic
ratio for
profiler,
u/U
7.5
5.0
6.0
1.4
1.6
Integrated
exposure H.'
(Ib/vehicle-mlle)
0.01st/
o.ozok/
0.012-/
0.019
0.010
a/ Hi-vol measurement.
b/ Isokinetic.
cj Total concentration measured by Sierra impactor substrates and backup filter.
d_/ Calculated by procedure described in Appendix.
-------
TABLE 7. LEAD CONCENTRATION AND EXPOSURE MEASUREMENTS
Ni
Lead concentration (vg/m )
at 2 m above
ground
Downwind, including background
Run
3
5
6
15
16
Background!/
0.46
0.60
0.56
0.72
0.63
Profiler^
1.42
2.03
4.62
2.08
1.47
Standard
Hi-Vol§/
1.82
2.76
2.20
2.51
1.59
Cascade
ImpactorS.'
1.7
3.0
±1
1.6
1.2
Isokinetic
ratio for
profiler,
u/U
7.5
5.0
6.0
1.4
1.6
Integrated
exposure^'
(g/vehicle-mile)
0.03
0.09
0.13
0.07
0.05
§_/ Hi-Vol measurement.
v
b_/ Isokinetic.
c_/ Total concentration measured by Sierra impactor substrates and backup filter.
d/ Calculated by procedure described in Appendix.
e_/ Possible sample contamination.
-------
Fine particles Coarse particles
(d < 5 yim) (d > 50 ym)
Exposure multiplier U/u 1
Concentration multiplier 1 u/U
where u = Sampling intake velocity at a given elevation
U = Wind velocity at same elevation as u
d = Aerodynamic (equivalent sphere) particle diameter
For a particle size distribution containing a mixture of fine, intermediate,
and coarse particles, the isokinetic correction factor is an average of the
above factors, weighted by the relative proportion of coarse and fine particles.
For example, if the mass of fine particles in the distribution equals twice
the mass of the coarse particles, the weighted isokinetic correction for ex-
posure would be:
1/3 [2(U/u) + l]
4.3 PARTICLE SIZE ADJUSTMENT
A particle size adjustment factor is used for determining an emission
factor representing specific particle size ranges, such as particles smaller
than 30 u or 5 u. As stated earlier, a cyclone preseparator was used in con-
junction with a high-volume cascade impactor to measure airborne particle size
distribution. The purpose of the preseparator was to remove coarse particles
which otherwise would tend to bounce through the impactor to the backup filter,
thereby causing fine-particle measurement bias.
Table 8 presents a comparison of the particle sizing results for total
particulate and lead particulate. The effective cutoff diameter of the im-
pactor stages was calculated on the basis of density of 2.5 g/cnH for particu-
late and 5 g/cnr* for lead. The data given in Table 8 are from plots of particle
diameter (um) versus percent less than stated size on log-probability scale
graph paper.
The particle size distributions indicate that the lead particles are
essentially all less than 30 um in diameter; thus, the particle size adjust-
ment factor is approximately equal to 1. Table 8 also indicates that the
mass median diameter for lead is less than 1 um. This agrees with a study in
the Cincinnati area indicating mass median diameters in the range of 0.18 to
0.42 u.§-'
23
-------
TABLE 8. PARTICLE SIZE DATA
Particulate3-'
Run
3
5
6
15
16
Site
37th Street
37th Street
37th Street
Fairfax
Fairfax
MMl£/
(ym)
5.5
3.3
2.8
6.5
5.3
Weight %
< 30 ym
87
97
99
87
92
Weight %
< 5 Vm
48
64
70
41
42
Fine
particle
ratio!/
0.55
0.66
0.71
0.47
0.46
MMD£/
(ym)
0.6
0.2
< 0.1
1
1
Lead^
Weight %
< 30 ym
98
98
> 99
93
88
Weight %
< 5 ym
87
90
98
76
74
Fine
particle
ratio!/
0.89
0.92
-0.98
0.82
0.84
aj Based on density of 2.5 g/cm .
b_/ Based on density of 5 g/cm^.
cf HMD = Mass Median Diameter.
d/ Ratio = (weight % < 5 urn) -r (weight 7. < 30 urn).
-------
4.4 TOTAL LEAD EMISSION FACTOR
The total lead emission factors developed in this study are summarized in
Table 9. These emission factors represent particles smaller than 30 um in
diameter. These are the same values presented in Table 7 for integrated ex-
posure.
Total lead is comprised of lead from vehicle exhaust and from dust reen-
trainment. A description of the calculation procedures used in determining the
total lead emission factor is given in the Appendix. The vehicle exhaust por-
tion of the emission factor was calculated as described in Section 5.2 and the
dust reentrainment emission factor was calculated by difference.
TABLE 9. MEASURED TOTAL PARTICULATE LEAD EMISSION FACTORS
Total lead
emission factor—
Run
3
5
6
15
16
Location
37th Street (midday)
37th Street (rush hour)
37th Street (rush hour)
Fairfax Trafficway
Fairfax Trafficway
(g/vehicle mile)
0.03
0.09
0.13
0.07
0.05
(g/vehicle
0.02
0.06
0.08
0.04
0.03
km)
aj Measured total particulate lead emissions are the sum of vehicle exhaust
and reentrained dust.
25
-------
SECTION 5.0
EMISSION FACTOR CONTRIBUTIONS
5.1 MRI SAMPLING SITE CHARACTERISTICS
The following paragraphs describe the differences in the MRI sampling lo-
cations which may explain the variation in the measured total particulate lead
emission factor. This information is helpful in the determination of the con-
tributions of lead from vehicle exhaust and lead from reentrained dust.
37th Street (midday) - Sampling for run 3 was performed during early
afternoon (nonrush hour). The wind conditions were extremely light. Vehicle
speed may be assumed to have been close to the speed limit of 30 mph (assume
25 mph). Vehicle mix was primarily older cars. Sampling was performed near
an intersection controlled by a traffic light.
37th Street (rush hour) - For runs 5 and 6, sampling was performed during
the afternoon (including rush hour). Wind conditions were light (less than
5 mph). Vehicle speed was approximately 20 mph. Change of shift for a major
assembly plant (located 3 blocks east) provided a high percentage of the
traffic. Vehicle mix was 707, automobiles plus buses and trucks.
Fairfax Trafficway - Street dust loadings were lighter for this site than
for 37th Street; however, background levels were extremely high due to inter-
ference from a merging street and various industrial sources. Sampling was
performed during afternoon rush hour which consisted of traffic in both direc-
tions for shift changes. Vehicle speed was considerably less than the speed
limit (assume an average of 15 mph).
5.2 LEAD FROM VEHICLE EXHAUST
An average lead emission factor for lead in vehicle exhaust was derived
from information presented in Reference 9. The following paragraphs describe
vehicle exhaust emissions for (a) composite vehicle operation, and (b) con-
stant cruise speeds.
Table 10 summarizes vehicle exhaust lead emission factors based on com-
posite operation (i.e., includes speed correction, temperature, and hot/cold
weighting correction) for 1974 through 1995, based on an average vehicle speed
of 30 mph.-/
26
-------
TABLE 10. PROJECTED VEHICLE EXHAUST LEAD EMISSION FACTORS
(COMPOSITE OPERATION)?-/
Emission factori/
Year (a/vehicle mile)
1974 0.131
1975 0.08^
1976 0.07^
1977 0.062
1978 0.047
1979 0.028
1980 0.026
1981 0.024
1983 0.011
1985 0.006
1990 0.002
1995 0.002
a/ For typical driving patterns: Composite of interrupted and freely flowing
traffic.
b/ Estimated value.
27
-------
Since during the MRI emission testing program, the vehicles were operating
at nearly steady speeds, it was necessary to determine lead emission factors at
constant cruise speeds.
Q /
Based on previously reported data—' Figure 8 shows worst-case curve of the
percentage of burned lead exhausted versus vehicle cruise speed. These data can
be used in the following equation to derive an emission factor for lead from
vehicle exhaust:
EF . CPE
.
where EF = Worst-case lead emission factor for vehicle exhaust at a
constant speed in grams per vehicle mile.
PE = Percentage of burned lead that is exhausted as derived from
Figure 8.
LC = Lead content in gasoline, in grams per gallon.
MPG = Fuel economy, in miles per gallon of gasoline consumed.
From Figure 8, one can determine for constant vehicle speeds of 15 to 40 mph,
the percentages of burned lead exhausted are approximately 10 to 327», respec-
tively.
The average lead content of leaded gasoline during the periods of sampling
(Fall 1975 and Spring 1976) is stated to be 1.72 g of lead per gallon of gaso-
line.—' This figure will be reduced to approximately 0.5 g of lead per gallon
of gasoline by October 1, 1979.
Assuming fuel economy of 15 mpg (estimate) and lead content equal to
1.7 g/gal., the vehicle exhaust lead emission factors are given in Table 11.
The emission factors in Table 11 are based on constant cruise speeds.
TABLE 11. VEHICLE EXHAUST LEAD EMISSION FACTORS
(CONSTANT CRUISE SPEEDS)
Vehicle Lead emission factor
speed for vehicle exhaust—'
_ (mph) _ (g/vehicle/mile) _
15 0.011
20 0.018
25 0.022
30 0.025
35 0.031
40 0.036
28
-------
80
70
60
x 50
LU
o
UJ
Z 40
< 30
20
10
A Hirschler and Gilbert, 1957
Q Habibi, 1970
OTer Haar, 1972
• Ganley and Springer, 1973
• Bradow, 1976
10
20 30 40
VEHICLE CRUISE SPEED (wph)
60
70
Figure 8. Percentage of Burned Lead Exhausted Versus
Vehicle Cruise Speed
29
-------
Lead emissions from vehicle exhaust increase rapidly during vehicle ac-
celeration, deceleration, cold engine operation, and high vehicle speed. This
is evident by comparison of equivalent lead vehicle exhaust emission factors
for composite operation versus constant cruise speed. For 1975-1976 and
30 mph vehicle speed, the composite operation factor is approximately 0.075 g/
vehicle mile (see Table 10) and the constant cruise speed factor is 0.025 g/
vehicle mile (see Table 11). This gives a factor of three correction for stop
and go traffic. In addition, the mass median diameter of lead emissions in-
creases with vehicle age.—'
The emission factor for lead from vehicle exhaust can be calculated for
each MRI run using the data in Table 11, and if applicable, a factor of three
adjustment for stop and go traffic. The resulting vehicle exhaust lead emis-
sion factors are given in Table 12.
For Run 3, the vehicle exhaust emission factor represents constant speed
driving. The value of 0.02 g/vehicle mile is taken directly from Table 11,
using an average vehicle speed of 25 mph. Runs 5 and 6 are based on 20 mph
and Runs 15 and 16 are based on 15 mph. However, for these latter vehicle
exhaust emission factors, the factor of three correction was applied to adjust
the emission factors for stop and go traffic.
5.3 LEAD FROM DUST REENTRAINMENT
The emission factor for lead from dust reentrainment was calculated in
this study as the difference between the total lead emission factor and the
vehicle exhaust lead emission factor. This section provides a description
of another method for determining lead from dust reentrainment which serves
as a cross-check.
A functional relationship between the computed total reentrained particu-
late emission factor and the measured silt loading (excluding curbs) is defined
in the following equation:—'
e = KLs Eq. (2)
where e = Particulate emission factor (kg/vehicle kilometers)
K = Proportionality constant (vehicle""^-)
L = Surface loading excluding curbs (kg/km)
s = Silt content of the surface material (fraction)
As an example, substitution of appropriate data into Eq. (2) for Fairfax
Trafficway gives the following emission factor for total reentrained particu-
lates:
e = 91 x 10'5 x (152) x (0.06) = 13.4 g/vehicle mile
30
-------
TABLE 12. SUMMARY OF VEHICLE EXHAUST LEAD EMISSION FACTORS
Vehicle exhaust
Traffic lead emission
speed factor
Run Site (mph) characteristics (gm/veh-mile)
37th Street (midday) 25
37th Street (rush hour) 20
Light, steady
Steady, stop and
go
0.02§/
0.05^
15 \
16 J
Fairfax Trafficway
15
Heavy, steady
0.03^
a/ From Table 11.
jb/ From Table 11 using a correction factor for stop and go traffic equal to 3.
31
-------
The emission factor for lead can be calculated as the product of the particu-
late emission factor and lead content of the surface material. From Figure 7,
the weighted average lead content of street loading excluding curbs for Fairfax
Trafficway is 0.177». Thus, the lead emission factor from the reentrained dust
would be (13.4) x (0.17/100) = 0.02 g/vehicle-mile.
5.4 MRI RESULTS
Table 13 presents the total particulate lead emission factors developed
by MRI. In addition, proposed factors for particulate lead reentrainment by
traffic are presented.
The vehicle exhaust lead emission factor was determined using the meth-
odology described in Section 5.2. Specifically, average vehicle speed and
assumed fuel economy can be substituted into Eq. (1). Since Eq. (1) assumes a
constant cruise speed, the resulting emission factor should then be multiplied
by the exhaust multiplier which is based on specific site and traffic character-
istics. The exhaust multiplier increases the emission factors to values com-
parable to 1974 to 1977 data presented in Table 10.
The lead emission factor for reentrained dust is the difference between
the measured total emission factor (given in the last column of Table 13) and
the vehicle exhaust emission factor. As indicated in Table 13, the lead re-
entrainment factor seems to be approximately equivalent to the vehicle exhaust
factor.
It is clear from Table 10 that the projected lead emissions from vehicle
exhaust on a year-by-year basis will decrease in direct proportion to the re-
duction in the lead content of gasoline burned. It is also reasonable to assume
that lead emissions from dust will decrease in the same way, because the source
of lead in road surface dust is vehicle combustion of leaded gasoline.
32
-------
TABLE 13. SUMMARY OF PARTICUIATE LEAD EMISSION FACTORS
Lead emission factor (g/vehicle mile)
Vehicle Dust Measured
Run exhaust reentrainment total
3 0.02 0.01 0.03
5 0.05 0.04 0.09
6 0.05 0.08 0.13
Average 0.05 0.06 0.11
15 0.03 0.04 0.07
16 0.03 0.02 0.05
Average 0.03 0.03 0.06
33
-------
SECTION 6.0
COMPARISON OF RESULTS
Table 14 presents a comparison of lead data presented in this report, with
equivalent data contained in reports prepared by PEDCo Environmental!.' and by
GCA/Technology Division.—'
Figure 9 presents a plot of ambient lead concentrations versus sampling
height for the MRI, PEDCo and GCA studies. The profiles measured by MRI at
a distance of 3 m from the curb show a more pronounced effect of the traffic
sources, in comparison with the profiles measured by PEDCo and GCA at greater
distances from the curb.
6.1 PEDCo STUDY
A study performed by PEDCo Environmental—' used hi-vol measurements of
ground-level lead concentrations (i.e., concentrations at various distances
downwind from each road) to determine total lead emission factors. This study
included analysis of filters for 35 runs at four locations (undeveloped area,
park, residential, and commercial).
Total lead emission factors were calculated by PEDCo for 10, 20 and 30 m
distances from the road. The results are as follows:
Total lead emission factor
Distance downwind (g/vehicle mile)
(m) Range Average
10 0.016-0.201 0.068
20 0.007-0.319 0.068
30 <0.005-0.154 0.072
In order to calculate, by difference, an average lead emission factor for
dust reentrainment from the PEDCo data, the vehicle exhaust emission factor
was calculated by MRI assuming constant cruise speeds. The procedure used was
that given in Section 5.2.
34
-------
TABLE 14. COMPARISON OF LEAD RESULTS
I.
II.
Ill
IV.
7o lead in particulate samples
A. Upwind hi-vol
B. Street loading
C. Downwind hi-vol
Lead concentrations
(ug/m3) - see Figure 9
A. Upwind hi-vol
B. Downwind hi-vol
Particle size
Lead emission factors
(g/veh. mi.)
A. Total
B. Vehicle exhaust
C. Road dust reentrain-
ment
MRI
0.22-0.46
0.09-0.22
0.44-0.98
0.46-0.72
1.59-2.76
Fine (see
Table 8)
Sitei/
ABC
O.OJ, 0.11, 0.06
0.02, 0.05, 0.03
0.01, 0.06, 0.03
PEDCol/ GCAl/
u.u-z.of-
1.3-2.7 «44 um)
0.13-3.43 0.6-1.8
0.00-2.04^
0.39-5. 75k-/ 1-4
Fine*/
v /
0.069-'
0.036^
0.033d-/
a/ Horizontal measurements taken at various distances downwind from the road
resulted in increases in % lead.
b_/ Based on average of 35 runs.
c_/ Calculated using methodology described in Section 5.2 (average vehicle
speed = 40 mph; and constant cruise speed).
d_/ Calculated by difference; i.e., total emission factor minus vehicle
exhaust emission factor.
§_/ Site A - 37th Street (midday)
Site B - 37th Street (rush hour)
Site C - Fairfax Trafficway
35
-------
12
11
10
^ 6
en
D MRI (37th Street)
O MRI (Fairfax Trafficway)
o GCA
A PEDCo (Kansas City)
V PEDCo (Cincinnati)
-20-44m from Curb
OA
V
11 m from Curb
I I I I I I I I I I I I I I 1
0.5 1.0 1.5 2.0
Pb Concentration,
2.5 3.0 3.5
Figure 9. Comparison of Lead Concentrations at Various
Sampling Heights
36
-------
Twenty-seven out of the 35 PEDCo runs were conducted at locations with an
average traffic speed of 39 mph. The remaining eight tests were conducted at
a commercial site with some stop and go traffic. The average total lead emis-
sion factor for the 27 runs was 0.068 g/vehicle mile. The vehicle exhaust
emission factor is 0.036 g/vehicle mile for 40 mph (Table 11). This gives an
average dust reentrainment emission factor of 0.068 minus 0.036, or 0.032 g/
vehicle mile.
The PEDCo study also showed increased lead content of particulates at
further distances from the road. This indicates that the lead consists pri-
marily of fine particles, which is also indicated by the MRI results (see
Table 8).
6.2 GCA STUDY
A study performed by GCA—' used high-volume samplers mounted on a 40-ft
tower at heights of 10, 20, 30, and 37 ft. Thirteen 24-hr samples were made
at the intersection of two major downtown streets in Philadelphia.
The study indicated that there was no relationship between sampler
height and lead concentrations (see Figure 9). This appears to be due to
the enhanced vertical dispersion and due to the elevated sampling heights.
The GCA study, too, indicates that lead is concentrated in fine particles.
6.3 SUMMARY OF RESULTS
The results of this study plus other studies indicate that the lead emis-
sion factor for reentrained dust is approximately 0.03 g/vehicle mile for the
1975-1976 sampling period. It is apparent that decreasing the lead content in
gasoline will not only decrease the amount of airborne lead emitted from vehicle
exhaust, but also will decrease the amount of lead-containing dust reentrained
from paved roadways. With the reduction of lead in leaded gasoline and the
continued introduction of catalyst equipped vehicles into the vehicle distri-
bution, the lead emission factor for reentrained dust is expected to drop below
0.01 by 1980.
The following emission factors were calculated using the results of this
study and the data from other investigations:
Lead emission factor for 1975-1976
(g/vehicle mile)
Total Dust reentrainment
Range Average Range Average
Midwest Research Institute 0.03 to 0.11 0.06 0.01 to 0.06 0.03
PEDCo Environmental 0.005 to 0.319 0.07 0.03
Average 0.065 0.03
37
-------
Analysis of airborne particulate samples for lead particle size distribu-
tion shows that lead is concentrated in fine particles. The mass median diam-
eter for particulate lead is about 1 urn as compared to a mass median diameter
of about 5 urn for total airborne particulate. This result is substantiated
by results reported elsewhere which indicate that the lead content of airborne
particulate increases with distance from the curb.
38
-------
REFERENCES
1. Lead Analysis for Kansas City and Cincinnati, PEDCo Environmental, EPA
Contract No. 68-02-2515, Work Assignment No. 5, June 1977.
2. Particulate Study of the Philadelphia Air Quality Control Region, GCA, EPA
Contract No. 68-02-2345, 1977.
3. Cowherd, C., C. M. Maxwell, and D. W. Nelson, Quantification of Dust Entrain-
ment from Paved Roadways, Midwest Research Institute, EPA Contract No. 68-
02-1403, Task Nos. 7 and 25, EPA Publication No. 450/3-77-027, July 1977.
4. Cowherd, C., K. Axetell, C. M. Guenther, and G. Jutze, Development of Emis-
sion Factors for Fugitive Dust Sources, EPA Publication No. 450/3-74-037,
June 1974.
5. "Reference Method for the Determination of Suspended Particulates in the
Atmosphere (High Volume Method)," Federal Register, 36^:28, Appendix B,
22388-22390, November 25, 1971.
6. Day, J. P., M. Hart, and M. S. Robinson, Lead in Urban Street Dust, Nature.
253^:343-345, January 31, 1975.
7. Solomon, R. L., J. W. Hartford, J. L. Hudson, D. Neaderhouser, and J. J.
Stuckel, "Spatial Variation of Airborne Lead Concentration in an Urban
Area," Journal of the Air Pollution Control Association, 27_(11)-.1095-
1099, November 1977.
8. Lee, R. E., Jr., R. K. Patterson, and J. Wagman, Particle Size Distribution
of Metal Components in Urban Air, Environmental Science and Technology,
Vol. 2, No. 4, April 1968.
9. Maxwell, C. M., R. Bohn, R. Caiazza, and C. Cowherd, Development of HATREMS
Data Base and Emission Inventory Evaluation, EPA Publication No. EPA-450/
3-77-011, April 1977.
10. TerHaar, G. L., D. L. Lenane, J. N. Hu, and M. Brandt, "Composition, Size,
and Control of Automotive Exhaust Particulates," Journal of the Air Pol-
lution Control Association. 22(1):39-46, January 1972.
39
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GLOSSARY
Dry Sieving - The sieving of oven-dried aggregate by passing it through a series
of screens of descending opening size.
Enclosure - A structure which either partially or totally surrounds a fugitive
emissions source thereby reducing the amount of emissions.
Exposure - The point value of the flux (mass/area-time) of airborne particulate
passing through the atmosphere, integrated over the time of measurement.
Exposure, Integrated - The result of mathematical integration of partially dis-
tributed measurements of airborne particulate exposure downwind of a fugitive
emis s ions source.
Exposure Profiling - Direct measurement of the total passage of airborne par-
ticulate immediately downwind of the source by means of simultaneous multi-
point isokinetic sampling over the effective cross section of the fugitive
emissions plume.
Particle Diameter, Aerodynamic - The diameter of a hypothetical sphere of unit
density (1 g/cm3) having the same terminal settling velocity as the particle
in question, regardless of its geometric size, shape and true density.
Particle Diameter, Stokes - The diameter of a hypothetical sphere having the
same density and terminal settling velocity as the particle in question, re-
gardless of its geometric size and shape.
Particle Drift Distance - Horizontal distance from point of particle injection
into the atmosphere to point of removal by contact with the ground surface.
Particulate, Fine - Airborne particulate smaller than 5 ym in Stokes diameter.
Particulate, Suspended - Airborne particulate smaller in Stokes diameter than
30 ym, the approximate cut-off diameter for the capture of particulate
matter by a standard high-volume sampler, based on particle density of
2 to 2.5 g/cm3.
Road, Paved - A roadway constructed of rigid surface materials, such as asphalt,
cement, concrete and brick.
40
-------
Road Surface Dust Loading - The mass of loose surface dust on paved roadway,
per length of roadway, as determined by dry vacuuming.
Silt Content - The mass portion of an aggregate sample smaller than 75 ym in
diameter as determined by dry sieving.
41
-------
APPENDIX
EXAMPLE CALCULATION OF LEAD EMISSION FACTOR
(Run 5)
A. CALCULATION OF TOTAL LEAD EXPOSURE
The purpose of this subsection is to show the procedures for calculating
total lead exposure. Exposure is the flux (mass/area-time) of airborne particu-
late passing through the atmosphere, integrated over the time of measurement.
The basic data used in this calculation is the net filter and net wash sample
weights collected at sampling heights of 1, 2, 3, and 4 m by the MRI exposure
profiler.
RESULT
STEP 1 Compute Filter Pb Net Weight (ug)
= Filter Particulate Net Weight (ug)
x % Lead on Filter/100
Profiler 1 = 61,250 x (1.1/100) = 674
Profiler 2 = 55,600 x (0.84/100) = 467
Profiler 3 = 50,950 x (0.77/100) = 392
Profiler 4 = 40,350 x (0.68/100) = 274
STEP 2 Compute Wash Sample Pb Net Weight (ug)
- Wash Sample Particulate Net Weight (ug)
x 7. Lead in Wash Sample/100
Profiler 1 = 17,900 x (0.19/100) = 34
Profiler 2 = 17,350 x (0.23/100) = 40
Profiler 3 = 11,000 x (0.31/100) = 34
Profiler 4 = 12,950 x (0.30/100) = 39
42
-------
RESULT
STEP 3 Determine Total Pb Sample Weight (ug)
= Filter Pb Net Weight (ug) from Step 2
+ Wash Sample Pb Net Weight from Step 2
Profiler 1 = 674 + 34 = 708
Profiler 2 = 467 + 40 = 507
Profiler 3 = 392 + 34 = 426
Profiler 4 = 274 + 39 = 313
STEP 4 Calculate Pb Concentration
= Total Pb Sample Weight (ug) from Step 3
-r Volume of Air Sampled (m^)
Profiler 1 - 708/217 3.27
Profiler 2 = 507/249 2.03 (see
Table 7)
Profiler 3 = 426/272 1.56
Profiler 4 = 313/288 1.09
STEP 5 Hi-Vol Pb Concentration (ug/m) Excluding Background
= Subtract Upwind (Background) Hi-Vol Pb Concentration
) given in Table 7 from Profiler Concentrations
) given in Step 4
Profiler 1 = 3.27 - 0.60 = 2.67
Profiler 2 = 2.03 - 0.60 = 1.43
Profiler 3 = 1.56 - 0.60 = 0.96
Profiler 4 = 1.09 - 0.60 = 0.49
STEP 6 Compute Total Pb Net Mass (ug)
= Hi-Vol Pb Concentration, Excluding Background (ug/m^)
given in Step 5
O
x Volume Air Samples (m )
Profiler 1 = 2.67 x 217 = 578
Profiler 2 = 1.43 x 249 = 356
Profiler 3 = 0.96 x 272 = 261
Profiler 4 = 0.49 x 288 = 141
43
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RESULT
STEP 7 Determine Area Under Exposure Profile (mg-ft)
Plot Total Pb Net Mass (ug)
Versus Sampling Height (m)
Graphically Integrate
Area = 1,637 ug-m x 0.00328 mg-ft/ug-m 5.37
STEP 8 Calculate Total Pb Exposure (g/veh. mi.)
= Area (mg-ft) given in Step 7 -:- No. of Vehicle Passes
given in Table 5
x 5280 (ft/mi.) x 36 (intake conversion) 0.452
x 10-3 (g/mg)
= (5.37 -f 2260) x 5280 x 36 x 10'3
B. CALCULATION OF TOTAL LEAD EMISSION FACTOR
The purpose of this subsection is to present the procedure for con-
verting total lead exposure to an isokinetic emission factor representing
particles smaller than 30 um in diameter.
STEP 1 Calculate Isokinetic Emission Factor (g/veh. mi.)
Correct Total Pb Exposure to
Isokinetic Conditions Using MRI
Procedures (see Section 4.2)
= 0.452 x (U/u)
= 0.452 x 0.2 = 0.090 (see
Table 7)
STEP 2 Calculate Total Pb Emission Factor
(Smaller than 30 um in diameter)
= Isokinetic Emission Factor (g/veh. mi.)
x Fraction < 30 um (from Table 8)
= 0.090 x 0.98 = 0.09
44
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-450/3-78-021
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
A Lead Emission Factor for Reentrained Dust
• from a Paved Roadway
5. REPORT DATE
April 1978
6. PERFORMING ORGANIZATION CODE
J. AUTHOR(S)
Christine M. Maxwell and Daniel W. Nelson
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Midwest Research Institute
425 Volker Boulevard
Kansas City, MO 64110
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-02-2609 Task No.2
12. SPONSORING AGENCY NAME AND ADDRESS
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
Project Officer - Charles C. Masser
16. ABSTRACT
The results of this study indicate that the lead emission factor for reen-
trained dust is approximately 0.03 g per vehicle mile for the 1975-1976 sampling
period. That approximation was calculated using the results of this study and
the data from other investigations.
It is apparent that decreasing the lead content in gasoline will not only
decrease the amount of airborne lead emitted from vehicle exhaust, but also will
decrease the amount of lead-containing dust reentrained from paved roadways. With
the reduction of lead in leaded gasoline and the continued introduction of catalyst
equipped vehicles into the vehicle distribution, the lead emission factor for
reentrained dust is expected to drop below 0.01 by 1980.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Lead Emissions
Emission Factor
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
50
20. SECURITY CLASS (Thapagej
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
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