&EPA
United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/4-83-006
March 1983
Air
Section 7.5, Iron
And Steel
Production
An AP-42 Update pf
Open Source Fugitive
Dust Emissions
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EPA-450/4-83-006
Section 7.5, Iron
And Steel Production
An AP-42 Update Of Open
Source Fugitive Dust Emissions
By
Midwest Research Institute
Kansas City, Missouri
Contract No. 68-02-3177
EPA Project Officer: Frank M. Noonan
Prepared For
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air, Noise and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park.. NC 27711
March 1983
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This report has been reviewed by the Office of Air Quality Planning and
Standards, U.S. Environmental Protection Agency, and approved for publica-
tion as received from Midwest Research Institute, Kansas City, Missouri.
Approval does not signify that the contents necessarily reflect the views
and policies of the U.S. Environmental Protection Agency, neither does men-
tion of trade names or commercial products constitute endorsement or recom-
mendation for use.
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CONTENTS
1.0 Introduction
2.0 Methodology for Identification of Candidate Emission Factors.
2.1 Literature search
2.2 Screening criteria
2.3 Final selection
3.0 Emission Factor Quality Rating Scheme
3.1 Rating of test data
3.2 Rating of emission factors
4.0 Candidate Emission Factors
4.1 Test report 1 (1978)
4.2 Test report 2 (1979)
5.0 Emission Factors Recommended for AP-42
5.1 Criteria for recommendations
5.2 Recommendations
5.3 Emission factor applicability
References
1
3
3
3
3
5
5
5
9
9
12
15
15
15
17
18
11
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1.0 INTRODUCTION
In assessment and control of air pollution, there is a critical need
for reliable and consistent data on the quantity and characteristics of emis-
sions from the numerous sources that contribute to the problem. The large
number of individual sources and the diversity of source types make con-
ducting field measurements of emissions impractical source by source, at
each point of release. The only feasible method of determining pollutant
emissions for a given community or area is to make general emission esti-
mates typical of each of the source types.
Calculation of the estimated emission rate for a given source requires
data on source extent, uncontrolled emission factor and control efficiency.
The mathematical expression for this calculation is as follows:
R = Me (1 - c) (1)
where R = mass emission rate
M = source extent
e = uncontrolled emission factor, i.e., rate of uncontrolled
emissions per unit of source extent
c = fractional efficiency of control
The emission factor is an estimate of the rate at which a pollutant is re-
leased to the atmosphere divided by the level of source activity.
The document "Compilation of Air Pollutant Emission Factors" (AP-42),
published by the U.S. Environmental Protection Agency (EPA) since 1972, is
a compilation of emission factor reports for the most significant emission
source categories. Supplements to AP-42 have been published for both new
emission source categories and for updating existing emission source cate-
gories, as more information about sources and control of emissions has be-
come available.
Because the national effort to control industrial sources of pollution
has focused on discharge from stacks, ducts or flues, most of the emission
factors reported in AP-42 apply to ducted emission sources. Recently how-
ever, evidence has mounted which indicates that fugitive (nonducted) emis-
sions contribute substantially to the impact of industrial operations and
in some industries may be greater than the stack emissions. This points to
the need for emission factors which are applicable to fugitive emissions.
Industrial sources of fugitive particulate emissions may be divided
into two classes—process sources and open dust sources. Process sources
are fully or partially enclosed operations that alter the chemical or phys-
ical properties of a feed material. Examples of process sources are crush-
ers, sintering machines, and metallurgical furnaces. Open dust sources are
those that entail generation of emissions of solid particles by the forces
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of wind and machinery acting on exposed materials. Open dust sources in-
clude open transport, storage and transfer of raw intermediate and waste
aggregate materials.
Emission factors for sources of primary particulate emissions have
been compiled in AP-42. However, only a small portion of these values
apply to either process fugitive emissions or open dust sources. Section
11.2 of AP-42 currently provides open dust source emission factors for
paved and unpaved roads, agricultural tilling, aggregate storage piles and
heavy construction operations.
Because of the recognized importance of open dust sources, largely de-
termined from recent receptor-oriented investigations of source culpability..
the rate of test data accumulation for these sources has increased substan-
tially. For this reason most of the emission factors reported in AP-42 for
open dust sources are in serious need of updating.
The purpose of this report is to present background information in
support of a revised AP-42 Section 7.5, Iron and Steel Production incor-
porating emission factors for open dust sources. This report is organized
by section as follows:
Section 2 - Methodology for identification of candidate emission factors
Section 3 - Emission factor quality rating scheme.
Section 4 - Candidate emission factors.
Section 5 - Emission factors recommended for AP-42.
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2.0 METHODOLOGY FOR IDENTIFICATION
OF CANDIDATE EMISSION FACTORS
2.1 Literature Search
The first step in the identification of candidate open dust source
emission factors for Section 7.5 was a search of the published literature.
The literature search was begun by a review of MRI's in-house library of
documents relating to fugitive dust emissions and emission factor develop-
ment. A supplemental computerized literature search was performed to verify
that all pertinent documentation was indeed maintained at MRI. The search,
performed by EPA Library Services, examined Chemical Abstracts, Engineering
Index, Environmental Abstracts, and National Technical Information Service
files.
2.2 Screening Criteria
In order to reduce the amount of literature which dealt in some way
with fugitive dust emissions in the iron and steel industry to a final
group of references pertinent to this update, five criteria were used:
1. The information in the reference document must deal with actual
emission factor development. Many documents discuss emission
factors but do not derive them.
2. Source testing must be part of the referenced study. Some
reports develop emission factors by applying assumptions to exis-
ting factors.
3. The referenced study must deal with open dust source emissions.
Process fugitive emissions such as crushing, screening, and
grinding are not pertinent to this investigation.
4. The document must constitute the original source of test data.
For example, a convention or symposium paper was not included if
the original study was already contained in a previous document.
5. The results of the referenced study must not be presently incor-
porated in AP-42. The purpose of this study is to recommend up-
dating AP-42 with research results not previously contained in
AP-42. If possible, however, new test data are to be combined
with previous data (used to develop the current AP-42 emission
factor) in deriving an updated emission factor.
2.3 Final Selection
A final set of reference materials was collected after scrutinizing
all possible reports, documents, and information with the four criteria
stated above. Table 1 lists the final set of primary reference documents.
This set of documents will be reviewed with the criteria stated in Section 3
to determine the candidate emission factors listed in Section 4.
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TABLE 1. PRIMARY LIST OF TEST REPORTS
1. R. Bohn, et al., Fugitive Emissions from Integrated Iron and Steel Plants,
EPA-600/2-78-050, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, March 1978.
2. C. Cowherd, et al., Iron and Steel Plant Open Source Fugitive Emission
Evaluation, EPA-600/2-79-103, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, May 1979.
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3.0 EMISSION FACTOR QUALITY RATING SCHEME
In selecting candidate open dust sources emission factors for inclu-
sion in AP-42, the principal consideration centered around the reliability
of each factor being considered in relation to the reliability factors cur-
rently reported in AP-42 for the same source. This section describes the
emission factor quality rating scheme used in this study. It is a refine-
ment of the revised rating model developed by EPA for AP-42 emission fac-
tors, as described in Reference 3. The scheme entails the rating of test
data quality followed by the rating of the emission factor(s) developed
from that test data.
3.1 Rating of Test Data
Test data that were developed from well documented, sound method-
ologies were assigned an A rating. Data generated by a methodology that
was generally sound but either did not meet a minimum test system require-
ment or lacked enough detail for adequate validation received a B rating.
In evaluating whether an upwind-downwind sampling strategy qualified
as a sound methodology, the following minimum test system requirements were
used. At least five particulate measuring devices must be operated during
a test, with one device located upwind and the others located at two down-
wind and three crosswind distances. The requirements of measurements at
crosswind distances is waived for the case of line sources. Also wind di-
rection and speed must be recorded concurrently on-site.
The minimum requirements for a sound exposure profiling program were
the following. A vertical line grid of at least three samplers is suffici-
ent for measurement of emissions from line or moving point sources while a
two-dimensional array of at least five samplers is required for quantifi-
cation of fixed virtual point source emissions. At least one upwind sam-
pler must be operated to measure background concentration, and wind speed
must be measured concurrently on-site.
Neither the upwind-downwind nor the exposure profiling method can be
expected to produce A-rated emissions data when applied to large, poorly
defined area sources, or under very light and variable wind flow conditions.
In these situations, data ratings based on degree of compliance with mini-
mum test system requirements were reduced one letter.
3.2 Rating of Emission Factors
After the test data supporting a particular single-valued emission fac-
tor were evaluated, the criteria presented in Table 2 were used to assign a
quality rating to the resulting emission factor. These criteria were devel-
oped to provide objective definition for: (a) industry representativeness;
and (b) levels of variability within the data set for the source category.
The rating system obviously does not include estimates of statistical con-
fidence, nor does it reflect the expected accuracy of fugitive dust emission
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factors relative to conventional stack emission factors. It does however
serve as a useful tool for evaluation of the quality of a given set of emis-
sion factors relative to the entire available fugitive dust emission factor
data base.
TABLE 2. QUALITY RATING SCHEME FOR SINGLE-VALUED EMISSION FACTORS
Code
1
2
3
4
5
6
7
8
9
No. of
test sites
> 3
> 3
2
2
-
-
1
1
I
No. of
tests
per site
> 3
> 3
> 2
> 2
-
-
2
2
1
Total
No. of
tests
-
-
> 5
> 5
> 3
> 3
2
2
1
Test data
variability
< F2
> F2
< F2
> F2
< F2
> F2
< F2
> F2
-
Adjustment
for EF,
rating
0
-1
-1
-2
-2
— 3
-3
-4
-4
a Data spread in relation to central value. F2 denotes factor of two.
Difference between emission factor rating and test data rating.
Minimum industry representativeness is defined in terms of number of
test sites and number of tests per site. These criteria were derived from
two principles:
1. Traditionally, three tests of a source represent the minimum re-
quirement for reliable quantification.
2. More than two plant sites are needed to provide minimum industry
representativeness.
The level of variability within an emission factor data set was defined
in terms of the spread of the original emission factor data values about
the mean or median single-valued factor for the source category. The fairly
rigorous criterion that all data points must lie within a factor of two of
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the central value was adopted. It is recognized that this criterion is not
insensitive to sample size in that for a sufficiently large test series, at
least one value may be expected to fall outside the factor-of-two limits.
However, this is not considered to be a problem because most of the current
single-valued factors for fugitive dust sources are based on relatively
small sample sizes.
Development of quality ratings for emission factor equations also re-
quired consideration of data representativeness and variability, as in the
case of single-valued emission factors. However, the criteria used to as-
sign ratings (Table 3) were different, reflecting the more sophisticated
model being used to represent the test data. As a general principle, the
quality-rating for a given equation should lie between the test data rating
and the rating assigned to the corresponding single-valued factor. The
following criteria were established for an emission factor equation to have
the same rating as the supporting test data:
1. At least three test sites and three tests per site, plus an addi-
tional three tests for each independent parameter in the equa-
tion.
2. Quantitative indication that a significant portion of the emission
factor variation is attributable to the independent parameter(s)
in the equation.
Loss of quality rating in the translation of test data to an emission
factor equation occurs when these criteria are not met. In practice, the
first criterion was far more influential than the second one in rating an
emission factor equation, because development of an equation implies that a
substantial portion of the emission factor variaton is attributable to the
independent parameter(s). As indicated in Table 3, the rating was reduced
by one level below the test data rating if the number of tests did not meet
the first criterion, but was at least three times greater than the number
of independent parameters in the equation. The rating was reduced two le-
vels if this supplementary criterion was not met.
The rationale for the supplementary criterion follows from the fact
that the likelihood of including "spurious" relationships between the depen-
dent variable (emissions) and the independent parameters in the equation
increases as the ratio of number of independent parameters to sample size
increases. For example, a four parameter equation based on five tests
would exhibit perfect explanation (R2=1.0) of the emission factor data, but
the relationships contained in such an equation cannot be expected to hold
true in independent applications.
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TABLE 3. QUALITY RATING SCHEME FOR EMISSION FACTOR EQUATIONS
No. of No. of Total No. Adjustment ,
Code test sites tests per site of tests for EF rating
I > 3 > 3 > (9 + 3P) 0
2 > 2 > 3 > 3P -1
3 > 1 - < 3P -2
P denotes number of correction parameters in emission factor equa-
tion.
Difference between emission factor rating and test data rating.
8
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4.0 CANDIDATE EMISSION FACTORS
_ following sections discuss the test reports applicable to AP-42
Section 7.5. For each report, the method of field sampling is described,
including sampling equipment employed and the number and location of test
sites. A quality rating is assigned to the test data based on the rating
scheme described in Section 3. An A rating denotes that the test data were
developed from well documented, sound methodologies. Data generated by a
generally sound methodology which either does not meet the minimum test
system requirements or lacks enough detail for adequate validation receives
a B rating. Also as part of good documentation, the source tested must be
specifically described as to physical operation, mechanical equipment em-
ployed, and material of concern.
After presentation of the emission factor(s) from each test report, an
explanation is given for the emission factor quality ratings assigned ac-
cording to the rating schemes described in Section 3. This is done by in-
dicating the code from Table 2 or Table 3, as appropriate.
Unless otherwise noted, emission factors expressed in units of Ib/T
denote quantity of emissions per quantity of material transferred in a par-
ticular operation.
4.1 Test Report 1 (1978)
The field testing for this study was done at two different integrated
iron and steel plants, one in the west (Plant 1) and one in the east (Plant 2)
Table 4 shows which open dust sources were sampled and how many tests were
performed at each plant. Testing was confined to days with dry weather
(three or more days after rainfall over 0.5-in.) and consistent wind speed
and direction.
Exposure profiling was used in all of these tests. Cascade impactors
with cyclone preseparators were used for particle sizing. Other equipment
utilized were: (a) high-volume air samplers for determining upwind partic-
ulate concentrations; (b) dustfall buckets for determining downwind par-
ti cul ate deposition; and (c) recording wind instruments employed to deter-
mine mean wind speed and direction for adjusting the exposure profiler to
isokinetic sampling conditions.
The exposure profiling system employed in this study consisted of a
6-meter vertical tower (located within 5-meters downwind of the source)
with a crossbeam to support sampling intakes and anenometers. In sampling
emissions from a front-end loader dumping into a truck, a 5-meter crossbeam
was used and a total of six air samplers were operated. To sample emissions
from a mobile stacker, the tower with a 3-meter crossbeam and a total of
six air samplers was towed at a speed matching that of the stacker arm.
The vertical tower alone with four sampling intakes at equally spaced
heights was employed in tests of vehicle traffic on roadways. Background
concentration was measured at one site upwind for each test. This system
meets the minimum requirements as set forth in Section 3.1.
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TABLE 4. IRON AND STEEL SOURCE TESTING INFORMATION
(Test Report 1)
Operation
Batch-drop
Continuous-
drop
Vehicle traffic
Equipment
Front-end loader/
truck
Mobile stacker
Transfer station
Heavy-duty
vehicles
Average vehicle
mix
Material
High silt pro-
cessed slag
Low silt pro-
cessed slag
Pell eti zed
iron ore
Lump ore
Sinter
Unpaved roads
(dirt, fine slag)
Paved roads
Site
Plant 1
Plant 1
Plant 1
Plant 1
Plant 2
Plant 1
Plant 2
Plant 2
Test
date
4/77
4/77
4/77
4/77
6/77
4/77
6/77
6/77
No. of
tests
3
3
2
3
3
2
3
2
10 cu yd bucket and 35-ton truck.
This can be defined as the typical mix of vehicle type used at integrated
iron and steel plants.
The emission rates were determined by spacial integration (over the
cross section of the plume) of measurements of exposure (mass of particu-
lates collected divided by the area of air sampling intake) and then divid-
ing by the sampling time. The results of each test series were arithmeti-
cally averaged to determine a single-valued emission factor for each defined
operation. For all sources except the conveyor transfer station, the test
data were collected using a well-documented sound methodology and, there-
fore, are rated A. The test data for the conveyor transfer station are rated
B because of the light winds encountered during testing.
Table 5 presents the average emission factors determined, the range of
conditions tested, and the quality ratings assigned. The rating codes refer
to Table 2.
10
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TABLE 5. IRON AND STEEL EMISSION FACTORS, RANGE OF TEST CONDITIONS, AND RATINGS
(Test Report 1)
Range of conditions
Material /equipment/
operation
High silt slag batch-drop0
Low silt slag batch-drop
Ore pile stacking
pellets
Lump ore
Conveyor transfer
station (sinter)^
Unpaved road .
Heavy-duty vehicles
Paved road (average
vehicle mix)
No. of Silt
tests (%)
3 7.3
3 3.0
2 4.8
3 2.8-19.1
3 0.7
5 4.8-8.7
2 5.1
Wind
Moisture speed
(X) (nph)
0.25 2.2-4.2
0.30 1.3-3.1
0.64 2.3-4.5
2.0-4.3 1.8-2.2
c 1.0 Calm
4-9
Calm-4
Vehicle Vehicle
speed weight
(mph) (tons)
NA
NA
NA
NA
NA
14-30
12
NA
NA
NA
NA
NA
23-70
7-8
Suspended Fine
particulate particulate
emission emission
factor factor
0.048 Ib/T 0.014 Ib/T
0.017 Ib/T 0.0052 Ib/T
0.0070 Ib/T 0.0024 Ib/T
0.00070 Ib/T 0.00020 lb/1
0.046 Ib/T 0.017 Ib/T
21.6 Ib/VHT 8.6 Ib/VMT
0.95 Ib/VMT 0.49 Ib/VMl
Rating
code Rating
5 C
5 C
7 0
5 C
5 0
3 B
7 D
NA = Not appl icable.
a Particles < 30 pro Stokes
Particles < 5 pm Stokes
- = Information
diameter.
diameter.
C Emission factors are arithmetic mean of test
Emission factors are arithmetic mean of test
Emission factors are arithmetic mean of test
not contained in test report.
runs Al, A2 and A3
runs A4 , A5 and A6
from page
from page
3-23, Table
3-23, Table
runs A8 and A10 from page 3-23, Table 3-8
lano 1-71 Ta
3-8 of test report.
3-8 of test report.
of test report.
9 Emission factors are arithmetic mean of test runs E10, Ell and E12 from page 3-23, Table 3-8 of test report.
Emission factors are arithmetic mean of test runs A14, A15, El, E2 and E3 from page 3-22, Table 3-7 of test report
Emission factors are arithmetic mean of test runs E7 and E8 from page 3-22, Table 3-7 of test report.
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4.2 Test Report 2 (1979)
This study involved testing at three different integrated iron and steel
plants. Sources tested were vehicular traffic on unpaved roads, vehicular
traffic on paved roads, and storage pile stacking. Table 6 summarizes the
testing performed for this study. The testing and calculation methodology
was the same as that employed in Test Report 1; therefore the test data are
rated A.
Table 7 shows the average emission factors developed, the range of con-
ditions tested, and the assigned quality ratings. The rating codes refer
to Table 2.
TABLE 6. IRON AND STEEL SOURCE TESTING INFORMATION
(Test Report 2)
Operation
Equipment
Material
Site
Test
date
No. of
tests
Continuous-
drop
Vehicle traffic
Mobile stacker
Light-duty
vehicles
Medium-duty
vehicles
Average vehicle
mix
Iron pellets
Coal
Unpaved roads
(dirt/crushed
slag)
Unpaved roads
(crushed slag)
Paved road
Plant 3 6/78 3
Plant 1 7/78 1
Plant 1 8/78 3
Plant 2 8/78 6
Plant 3 7/78 6
12
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CO
TABLE 7. IRON AND STEEL EMISSION FACTORS, RANGE OF TEST CONDITIONS, AND RATINGS
(Test Report 2)
No. of Silt Moisture
Operation tests (%) (%)
Storage pile
stacking
Iron pel let
Coald
Unpaved road
Light duty6
Medium duty
Paved road
(average vehicle
mix)
3 1.4-1.8 2.6-3.5
1 5.9 4.8
3 9.0
6 4.3-5.3
6 6.8-13.2
Range of conditions Suspended Fine
Wind Vehicle Vehicle participate particulate
speed speed weight No. of emission emissiog
(mph) (mph) (tons) wheels factor factor
1.5-6.0 NA NA NA 0.0025 Ib/T 0.00056 Ib/T
3.0 NA NA NA 0.00014 Ib/T 0.000011 Ib/T
2.2-3.2 15 3-4 4 2.3 Ib/VMT 0.76 Ib/VMT
4.1-12.1 22-29 8-30 6-13 9.1 Ib/VMT 2.1 Ib/VMT
1.4-3.9 - 5-13 - 0.94 Ib/VMT 0.25 Ib/VMT
Rating
code Rating
5 C
9 E
5 C
5 C
4 C
NA = Not appl icable.
- = Information not
contained in test report.
a Particles < 30 urn Stokes diameter.
Particles < 5 urn
c Emission factors
Emission factors
Emission factors
Stokes diameter.
are arithmetic mean of test
are from page 58, Table 3-17
are arithmetic mean of test
runs H10, Hll and H12 from page 58, Table 3-17 of test report.
of test report.
runs F21, F22 and F23 from page 42, Table 3-7 of test report.
rune C77 Hirnnnh C.17 frnm nano A 7 Tahlp 1-7 nf to<;t rpnnrt
Emission factors are arithmetic mean of test runs F13 through F18 from page 50, Table 3-12 of test report.
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5.0 EMISSION FACTORS RECOMMENDED FOR AP-42
Presented below are recommendations for updating the AP-42 sections
for which new emission factor data are available as reviewed in Section 4.
5.1 Criteria for Recommendations
Three criteria form the basis for recommending addition of emission
factors to AP-42:
1. Emission factors are available for sources for which no factors
are currently reported in AP-42.
2. For sources that have factors currently reported in AP-42, addi-
tional factors of equal or higher quality rating are available.
3. When more than one emission factor of comparable rating are avail-
able for a given open dust source, they are combined, i.e., either
averaged to form a new single valued emission factor or added to
the data base supporting an updated emission factor equation. If
the ratings of available factors (including those already contained
in AP-42) differ by more than one level, then the factor (or fac-
tors) with the highest quality rating is the one that is recommended
In recommending emission factors for open dust sources, consideration
must be given to particle size. Equivalent aerodynamic diameter has become
the standard for characterizing the effects of particulate air pollution.
Therefore, aerodynamic particle diameter will be used to characterize the
recommended size specific emission factors.
5.2 Recommendations
Since no open dust sources emission factors are presented in AP-42 for
integrated iron and steel plants, it is recommended that all the candidate
factors given in Test Reports 1 and 2 be incorporated into AP-42. These
factors are summarized in Table 8. There is no overlap in the source ap-
plicability of these factors.
Because the emission factors in Test Reports 1 and 2 were presented by
particle size category defined by Stokes diameter, the following procedure
was employed to obtain emission factors in Table 8 for particle size cate-
gories defined by aerodynamic diameter.
1. The particle sizing data contained in the test report was
fitted to a log-normal curve. This data usually consisted
of percentages by weight of particulates smaller than a
given particle size expressed in Stokes diameter. These
Stokes diameters were converted to aerodynamic diameters
through multiplication by the square root of the particle
density before fitting the data to a log-normal curve.
15
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TABLE 8. IRON AND STEEL EMISSION FACTORS (Test Reports 1 and 2)
Emission factor by particle size
Operation
Continuous-drop
Batch-drop
—i Vehicle travel on
0-1 unpaved roads
Vehicle travel on
paved roads
Source
(material )
Conveyor transfer station
(sinter)
Pile formation - stacker
(pellet ore)
(lump ore)
(coal)
Front-end loader/truck
(high silt slag)
(low silt slag)
Light-duty vehicle
Medium-duty vehicle
Heavy-duty vehicle
Light-heavy (mix) vehicle
< 30
Total TSP (|.im)
0.026
0.0024
0.00030
0.00011
0.026
0.0088
1.8
7.3
14
0.78
< 15
(put)
0.018
0.0015
0.00019
0.000069
0.017
0.0058
1.3
5.2
9.7
0.56
(aerodynamic
< 10
(|jm)
0.013
0.0011
0.00015
0.000052
0.013
0.0043
1.0
4.1
7.6
0.44
diameter)
< 5
(Mm)
0.0084
0.00064
0.000081
0.000029
0.0080
0.0028
0.64
2.5
4.8
0.28
range
< 2.5
(pm)
0.0046
0.00034
0.000043
0.000015
0.0046
0.0016
0.37
1.5
2.7
0.15
Units
Ib/T
Ib/T
Ib/T
Ib/T
Ib/T
Ib/T
Ib/VMT
Ib/VMT
Ib/VMT
Ib/VMT
Test3
report
1
h
1 & 2D
1
2
1
1
2
2
1
1& 2b
Rating
0
B
C
E
C
C
C
C
B
C
- = Unable to be determined from information contained in test report.
a Test Reports 1 and 2 presented emission factors for size ranges defined by Stokes diameter. The factors have been adjusted to reflect an aerodynamic
diameter size range using information contained in the test reports. See Section 5.2 for procedure.
These factors are the arithmetic mean of the results for Test Reports 1 and 2.
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2. Appropriate data was obtained from the log-normal curve pro-
duced in Step 1 to define the particulate mass fractions con-
sisting of particles smaller than specific size cut-offs,
namely, 30 urn, 15 urn, 10 urn, 5 urn, and 2.5 urn aerodynamic
diameter.
3. The results of Step 2 (i.e., percents by weight less than
the specific particle sizes) were divided by the percent by
weight less than 30 urn Stokes. The ratios determined in
this step could then be multiplied by the given emission
factors to obtain the appropriate factor for each particle
size category.
v
4. Steps 1 through 3 were repeated for each test for which
particle size data were available. The average of the mass
fractions determined for each particle size category in Step
3 was multiplied by the appropriate emission factor for par-
ticles smaller than 30 urn Stokes diameter given in the test
report.
As an alternative to the single valued open dust emission factors given
in Table 8, empirically derived emission factor equations are presented in
Chapter 11 of AP-42. Each equation was developed for a source operation de-
fined on the basis of a single dust generating mechanism which crosses in-
dustry lines, such as vehicle traffic on unpaved roads. The predictive
equation explains much of the observed variance in measured emission factors
by relating emissions to parameters which characterize source conditions.
These parameters may be grouped into three categories: (a) measures of
source activity or energy expended (e.g., the speed and weight of a vehicle
traveling on an unpaved road); (b) properties of the material being dis-
turbed (e.g., the content of suspendible fines in the surface material on
an unpaved road; and (c) climatic parameters (e.g., number of precipitation
free days per year, when emissions tend to a maximum). Because the predic-
tive equations allow for emission factor adjustment to specific source con-
ditions, the equations should be used in place of the factors in Table 8,
if emission estimates for sources in a specific iron and steel facility are
needed.
5. 3 Emission Factor Applicability
A loss in the reliability (quality rating) of a single-valued emission
factor occurs if it is applied to a source operation or material other than
the operation and material that were tested in developing the emission fac-
tor. The source operation is defined by the equipment involved and the pre-
vailing wind conditions. The material is defined by its general composi-
tion, texture and moisture level.
A downgrading of one level in the quality rating should be made if the
available emission factor is applied to (a) the same operation with a simi-
lar material and (b) a similar operation with the same material. A similar
operation is defined as an operation within the same generic source cate-
gory but with a different type of equipment (for example, use of a power
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shovel rather than a front-end loader to load coal into trucks). A similar
material is defined as one with different composition (e.g., limestone ver-
sus coal) but with similar texture.
Most open dust source emission factors have been developed for dry con-
ditions (e.g., daytime periods with no measurable precipitation). This al-
lows for characterization of worst case conditions to bracket the high end
of the emissions range. The other extreme (zero emissions) corresponds to
complete mitigation resulting from natural and/or anthropogenic controls.
Most of the temporal variation in the rate of emission from an open
dust source (per unit of source extent or activity) is the result of meteo-
rological factors. Dust emissions are known to be strongly dependent on
the moisture level of the emitting material. In turn, temporal variations
in surface moisture are a function of precipitation and evaporation rates
during exposure.
Because available emission factors are based on field tests generally
performed with dry materials, seasonal and annual emission factors may re-
quire adjustment to higher moisture values reflective of long-term average
climatic and exposure conditions. In the same manner, adjustments should
be made to determine short-term emission factors for wet materials.
The generally higher quality ratings assigned to the equations presented
in Chapter 11 of AP-42 are applicable only if (a) reliable values of correc-
tion parameters have been determined for the specific sources of interest,
and (b) the correction parameter values lie within the ranges tested in de-
veloping the equations. Chapter 11 of AP-42 lists measured properties of
aggregate process materials and road surface materials in the iron and steel
industry, which can be used to estimate correction parameter values for the
predictive emission factor equations, in the event that site specific values
are not available. Use of mean correction parameter values from Chapter 11
reduces the quality ratings of the emission factor equation by one level.
REFERENCES*
1. R. Bohn, et al., Fugitive Emissions from Integrated Iron and Steel Plants,
EPA-600/2-78-050, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, March 1978.
2. C. Cowherd, et a!., Iron and Steel Plant Open Source Fugitive Emission
Evaluation, EPA-600/2-79-103,U.S.EnvironmentalProtection Agency,
Research Triangle Park, North Carolina, May 1979.
3. Technical Procedures for Developing AP-42 Emission Factors and Preparing
AP-42 Sections, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, April 1980.
Note that References 1 and 2 correspond to References 3 and 4 of AP-42
Section 7.5. Table 8 is equivalent to Table 7.5-1 of AP-42.
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