EPA-600/2-77-107f
July 1977
SOURCE ASSESSMENT:
HARVESTING OF GRAIN
State of the Art
by
R. A. Wachter and T. R. Blackwood
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
Contract No. 68-02-1874
ROAP No. 21AXM-071
Program Element No. 1AB015
EPA Task Officer: D. K. Oestreich
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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PREFACE
The Industrial Environmental Research Laboratory (IERL) of
EPA has the responsibility for insuring that pollution control
technology is available for stationary sources to meet the
requirements of the Clean Air Act, the Federal Water Pollution
Control Act and solid waste legislation. If control technology
is unavailable, inadequate, uneconomical or socially unaccept-
able, then financial support is provided for the development
of the needed control techniques for industrial and extractive
process industries. The Chemical Processes Branch of the
Industrial Processes Division of IERL has the responsibility
for investing tax dollars in programs to develop control
technology for a large number (>500) of operations in the
chemical industries.
Monsanto Research Corporation (MRC) has contracted with EPA
to investigate the environmental impact of various industries
which represent sources of pollution in accordance with EPA's
responsibility as outlined above. Dr. Robert C. Binning
serves as MRC Program Manager in this overall program entitled,
"Source Assessment," which includes the investigation of
sources in each of four categories: combustion, organic mate-
rials, inorganic materials, and open sources. Dr. Dale A.
Denny of the Industrial Processes Division at Research Triangle
Park serves as EPA Project Officer. Reports prepared in this
program are of two types: Source Assessment Documents, and
State-of-the-Art Reports.
111
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Source Assessment Documents contain data on emissions from
specific industries. Such data are gathered from the litera-
ture, government agencies and cooperating companies. Sampling
and analysis are also performed by the contractor when the
available information does not adequately characterize the
source emissions. These documents contain all of the infor-
mation necessary for IERL to decide whether a need exists to
develop additional control technology for specific industries.
State-of-the-Art Reports include data on emissions from speci-
fic industries which are also gathered from the literature,
government agencies and cooperating companies. However, no
extensive sampling is conducted by the contractor for such
industries. Sources in this category are considered by EPA
to be of insufficient priority to warrant complete assessment
for control technology decision making. Therefore, results
from such studies are published as State-of-the-Art Reports
for potentially utility by the government, industry, and
others having specific needs and interests.
This study was undertaken to provide information on air
emissions from harvesting of grain. In this project,
Mr. D. K. Oestreich served as EPA Task Officer.
IV
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CONTENTS
Preface
Figures
Tables
Symbols
I
II
III
IV
V
VI
VII
VIII
Introduction
Summary
Source Description
A. Process Description
1. Source Definition
2. Source Characteristics
3. Emission Sources
B. Geographical Distribution
Emissions
A. Selected Pollutants
B. Mass Emissions
C. Definition of the Representative Source
D. Source Severity
Control Technology
A. State of the Art
B. Future Considerations
Growth and Nature of the Industry
A. Present Technology
B. Emerging Technology
C. Trends
Unusual Results
Appendixes
A. Calculation of Pesticide Residue Con-
centration Downwind of Harvesting
Activity
B. A Method for Estimating TLV Values
for Compounds where None Exist
C. Sampling Methodology - Analysis and
Procedures
D. Sampling Results
Page
iii
vii
viii
ix
1
2
6
6
6
6
8
10
13
13
14
18
19
21
21
22
24
24
25
25
27
28
29
32
37
50
v
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CONTENTS (continued)
Pac
E. Derivation of the Representative
Source 58
F. Calculation of Source Severity 63
G. Determination of Maximum Pollutant
Concentrations 68
IX Glossary 74
X Conversion Factors and Metric Prefixes 77
XI References 79
VI
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FIGURES
Number Page
1 Area of grain harvested per state 10
2 Source severity distribution for free
silica 20
C-l Flow chart of atmospheric stability class
determination 40
C-2 Sampling apparatus 43
C-3 Field data form 44
C-4 Cassette sampling worksheet 49
VII
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TABLES
Number
1 Emission Rates and Emission Factors for
the Harvesting of Grain 3
2 Area of Grain Harvested per State 11
3 Emission Factors for Respirable Particu-
lates from Grain Harvesting 15
4 State and National Particulate Emissions
Burdens from the Harvesting of Grain 16
5 Mean Severities for Respirable Particulates 19
6 Harvesting Machines Utilized 24
A-l List of TLV's and Concentration of Pesti-
cide Residues on Grain Plants 30
B-l Selected Agricultural Chemicals 33
C-l Continuous Function for Lateral Atmospheric
Diffusion Coefficient a 41
C-2 Continuous Function for Vertical Atmos-
pheric Diffusion Coefficient a . 41
2
C-3 Explanation of Field Data Form Terms 45
D-l Average Grain Weight per Volume and
Volume per Area 51
D-2 Emission Rates from Wheat Harvesting
Machine Activity 52
D-3 Emission Rates from Sorghum Harvesting
Machine Activity 53
D-4 Emission Rates, Transport on the Field 53
D-5 Time-Averaged Emission Rates 55
E-l Number of Farms Harvesting Each Grain 59
E-2 Average Size of Each Grain Farm Per State 59
E-3 Population Density per Grain Harvesting State 61
F-l Distribution of Harvested Grain Land 67
F-2 Free Silica Severity Distribution 67
G-l Maximized Evaluation Criteria Values 72
Vlll
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SYMBOLS
Symbol Definition
A, AI, A2, A3, BI, Coefficients for atmospheric stabil-
B2, B3, GI, C2 ity functions
a, b, xf y Variables of original space
A, B, C, D, E, F Atmospheric stability classes
A, B, X, Y Variables of transformed space
A The grain field area harvested to
load an average truck
A The area of grain harvested per
b state
BCD Background concentration
D Representative distance to boundary
from the representative source
D The round trip distance traveled by
a truck on the field
E Emission factor
ET Emission factor for loading the har-
vested grain crop
E Emission factor for the harvest
machine activity
E The emission factor for free silica
from the harvest machine and trans-
port operations
E The composite emission factor for
grain harvesting
E Emission factor for the transport of
the harvested grain crop on the
field
exp Natural log base, e = 2.72
F The hazard factor for a pollutant
F National primary standard for total
suspended particulates
IX
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SYMBOLS (continued)
Symbol Def ignition
G Amount of grain transported in a
rural truck
h Physical stack height
H The height of the emission source
(= h + AH)
AH Plume rise
Hq The average harvest speed of a
harvesting machine
t-i, K2 Constants
The dose of a test material that
causes death in 50% of the rats
which have ingested the material
or which have been injected
M Dispersion model used
P The exponent of the time-averaged
concentration function
P_ Grain production
ppm Parts per million
P^ Production rate
K
Pq Percent of free silica detected as
b quartz
Q Emission rate of pollutants
Q Emissions from a source per length
u of distance
Qw Emission rate for the machine
harvesting activity
QT Emission rate for loading of the
trucks
C- The composite weighted emission
rate for grain harvesting
C" H The weighted emission rate for the
machine harvesting activity
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SYMBOLS (continued)
Symbol Definition
Q The weighted emission rate for
loading of trucks
Q Emission rate for transport on the
TR field
Q The weighted emission rate for the
transport of trucks on the field
R Respirable particulates
S Source severity
S1 Atmospheric stability classification
Sn Standard error of B (intercept)
ti
S Standard error of M (slope)
S Particulate severity (<7 ym)
S Source severity for representative
K plant
£L7 The average swath width of a har-
W/ * 11
vesting machine
Sv Standard error of estimate
X • Y
tj. The sampling time for concentration
measurements
t0 Sampling time for time averaging
o
T Total mass reading
T The time to harvest the harvest area
required to fill the average grain
truck
T Time required to load an average
grain truck
T The time to harvest one square kilo-
meter of grain
T Total time to harvest and load an
average truck full of grain
XI
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SYMBOLS (continued)
Symbol Definition
T Time required to travel the round
trip distance on a field
u Arithmetic mean wind speed
veh Vehicle
veh-m Vehicle-meters
V_ Volume of grain harvested per area
(j
V The speed of a truck on the field
O
ViL, Weight of grain harvested per volume
G
x Crosswind distance from a source
x. ith threshold limit values
x, y, z Coordinate downwind distance points
from source
z The standardized value of a random
variable
Z The value of standardized variable
a/2 that corresponds with a probability
of a/2
a The probability that a random vari-
able does not lie within a specified
area
A Difference between background con-
centration and concentration down-
wind of source
IT Pi, a constant 3.1416
a Standard deviation of horizontal
^ distance
a Standard deviation of vertical dis-
z tance
a The instantaneous vertical standard
z deviation
Xll
-------
Symbol
X
XK
max
v p
*max'
SYMBOLS (continued)
Definition
Downwind concentration
The concentration obtained from the
sampling time, tv
Js.
The concentration for the sampling
time, ts
Time-averaged maximum ground level
concentration
Time-averaged maximum ground level
particulate concentration
The dosage of pollutants from a
source
Xlll
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SECTION I
INTRODUCTION
Harvesting of grain refers to the physical activities of
cutting, threshing, picking, screening, cleaning, shelling,
loading, binding, and field transport of grain crops, all of
which cause air pollution. Grain is a general term referring
to wheat, rye, barley, oats, soybeans, flaxseed, corn, and
sorghum.
Data and information on air pollution from the harvesting of
grain are virtually nonexistent in the literature. This
study provides the data and information necessary for evalu-
ating the hazard potential of the pollutants. Evaluation
criteria are quantified to establish the need for developing
control technology.
This document presents the following information:
• A source definition
• Descriptions of the operations and sources of emissions
• Composition and hazard potential of the emissions
• Geographical distribution of the source
• Description of a representative source
• Severity of the source
• Trends in harvesting and present/future control
technology
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SECTION II
SUMMARY
Grain is harvested at over 380,000 farms in the U.S. which
produce wheat, rye, oats, barley, soybeans, flaxseed, corn,
and sorghum. These grains are cut, threshed, picked, cleaned,
screened, baled, loaded and transported from the fields,
usually by truck. The crops are harvested for use of the
cereal kernels or of the plant for forage and/or silage. An
average grain fcirm harvests 2.23 grain crops from an area of
0.98 km2 (240 acres).
The harvesting activities produce respirable particulates
(<7 ym geometric mean diameter) in the form of soil dust and
plant tissue fragments (called chaff). The soil dust contains
free silica. A residue of pesticides and microorganisms re-
mains on the chaff or is released with the particulate
emissions.
Emissions are generated by three harvesting operations: the
harvest machine activity, loading of the harvested crop, and
transport while on the field. The emission rates and factors
for total respirable particulates and particulates containing
free silica from these operations are presented in Table 1
along with their 95% confidence limits. The composite emission
rate for the entire source was weighted for the varying dur-
ations of the operations.
A maximum concentration for pesticide residues at 100 m
downwind is calculated to be four orders of magnitude less
2
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than the threshold limit values (TLV®'s). Thus further anal-
ysis was not required. The potential environmental risk of
microorganisms cannot be evaluated due to lack of a standard
or TLV. Specific allergenic reactions have been observed in
grain harvest workers, but the extent of epidemiological
hazard has not been defined.
A representative emission source is defined by the harvesting
of a single grain crop covering 0.44 ± 0.06 km2 (109 ±
13 acres) at the 95% confidence level. The distance to the
nearest affected population is 330 ± 122 m (1083 ± 400 ft)
at the 95% confidence level. The hazard potential of this
source is indicated by the severity, S, expressed by:
c -
where x = time-averaged maximum ground level pollutant
max concentration from a representative source
F = hazard factor for the pollutant
For criteria pollutants the hazard factor is the primary
ambient air quality standard (AAQS). For noncriteria
pollutants, this factor is the threshold limit value correc-
ted to a 24-hr exposure and including a safety factor (i.e.,
TLV • 8/24 • 1/100). The primary AAQS for particulate matter
is 260 yg/m3. The hazard factor for particulates containing
a maximum of 10% free silica is 2.76 yg/m3. The resulting
arithmetic mean source severities are 3.5 x 10~3 for respira-
ble particulates and £0.29 for free silica. The population
affected by a time-averaged ground level concentration "
for which \/F - 0.1 is zero for respirable particulates
and 28 persons for free silica particulates.
-------
The emissions burden for a source is the ratio of its mass
respirable particulate emissions to the total respirable
emissions of a state or the nation. The highest state emis-
sions burden is 0.12% for North Dakota. The national emis-
sions burden is 0.008%.
Industry growth in terms of area harvested is expected to be
13% higher than the 1972 figure by 1978, which will result
in a comparable growth of emissions. Specific air pollution
control technology for grain harvesting is presently non-
existent.
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SECTION III
SOURCE DESCRIPTION
A. PROCESS DESCRIPTION
1. Source Definition
This source includes the grains listed in the U.S. Department
of Agriculture Official Standards for Grain: wheat, rye,
oats, barley, flaxseed, soybeans, corn, and sorghum.1
Harvesting of these crops refers to the activities performed
to obtain the cereal kernels of the plant for grain or the
entire plant for forage and/or silage uses. These activities
are accomplished by machines that cut, thresh, screen, clean,
bind, pick, and shell these crops in the field. Harvesting
also includes the loading of the harvested crops into trucks
and transport of the crops on the grain field.
2. Source Characteristics
Grain crops are harvested for use of the cereal kernels or
the remainder of the grain plant. The various machines and
methods employed for harvesting depend on the use of the
crop.
Official United States Standards for Grain. U.S.
Department of Agriculture, Agricultural Marketing Service,
Grain Division., U.S. Government Printing Office.
Washington. Stock No. 0116-00094. June 2, 1974. 66 p.
6
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Crops harvested for the cereal kernels are cut as close as
possible to the inflorescence (the flowering portion con-
taining the kernels).2 This portion is threshed, screened,
and cleaned to separate the kernels from the plant. The
grain is then stored in the harvest machine while the remain-
der of the plant is discharged back onto the field.
Combines perform all of the above activities in one operation.
Binder machines are used just to cut the grain plants and tie
them into bundles or leave them in a row (called a windrow) in
the field.3'4 The crop is then allowed to dry for threshing
at a later date by a combine with a pickup attachment.
Corn is the only exception to the above procedures. It is
harvested by mechanical pickers, picker-shellers, and com-
bines with corn head attachments. These machines cut and
husk the ears from the standing stalk. The sheller unit also
removes the kernels from the ear. A binder is sometimes used
to cut and bind the entire corn plant. These bundles are
placed into piles (called shocks) to dry for husking at a
later date.4
Mowers, crushers, windrowers, field choppers, binders, and
similar cutting machines are used for harvesting the grasses,
stalks, and cereal kernels for forage and/or silage.5 These
machines cut the plants as close to the ground as possible
2Private communication. Mr. H. B. Drake. Montgomery County
Agricultural Extension Agency (Ohio). July 8, 1975.
3Wilson, H. K. Grain Crops, 2nd Edition. New York, McGraw-
Hill Book Co., 1955. 396 p.
4Kipps, M. S. Production of Field Crops, 6th Edition. New
York, McGraw-Hill Book Co., 1970. 790 p.
Encyclopaedia Brittanica, 1974 Edition. Volume 1 - Tech-
nology of Agriculture. Chicago, Encyclopaedia Brittanica,
Inc., 1974. p. 357-361.
-------
and leave them in a windrow. The plants are later picked up
by a baler which ties them into bundles. Pickup balers are
also used on previously threshed crops that were left in the
field.4
Harvested crops are loaded into trucks on the field. Grain
kernels are loaded through a spout from the combine. Forage
and silage bales are manually or mechanically placed in the
trucks. The harvested crop is then transported on the field
to a storage facility.
3. Emission Sources
Emissions are generated by three grain harvesting operations:
(1) crop handling by the harvest machine, (2) loading of the
harvested crop into trucks, and (3) transport by trucks on
the field.
Machines create particulates at the various areas where the
harvesting actions take place. Emissions occur at the points
where these activities are open, or material is discharged,
to the atmosphere. Wind then entrains particulate matter
which is composed of soil dust and plant tissue fragments
(chaff). This particulate matter has a respirable fraction
that contains free silica.
Particulate matter may also contain a residue of pesticides
that were applied to the crop prior to harvest.6 The
proportion of pesticide in the plant, increased by three
orders of magnitude, is assumed to represent the proportion
present in the dust. This results in a concentration (at
6Spear, R. C., and W. J. Popendorf. Preliminary Survey of
Factors Affecting the Exposure of Harvesters to Pesticide
Residues. American Industrial Hygiene Journal. 35;374-380,
June 1974.
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100 m downwind) which is four orders of magnitude less than
the threshold limit value (see Appendices A and B). Thus
further consideration of pesticides is not necessary.
Particulates from harvesting operations also contain various
microorganisms, such as bacteria and fungal growths.7 There
are 236 common types of microorganisms associated with grain
plants.8 These growths are present on the dust and release
spores when agitated by the vibration of the harvesting
machine.9 A standard for grain handling dust exposure has
not been promulgated due to lack of specifically identified
hazards other than the free silica in the particles.
Particulate emissions are generated in two other operations
which are not as complex as the harvest machine activities.
The loading of the harvested grain crop generates particu-
lates that are subject to wind entrainment during the free
fall of the harvested crop into the truck. Particulates
containing free silica are emitted during transport of the
material by trucks from the action of the truck tires on the
field.
7Harris, L. H. Allergy to Grain Dusts and Smuts. Journal of
Allergy and Clinical Immunology. 1£: 327-336, 1939.
8Dickson, J. G. Diseases of Field Crops, 2nd Edition. New
York, McGraw-Hill Book Co., 1956.
9Hirst, J. M. Chapter 47 - Spore Liberation and Dispersal.
In: Plant Pathology - Problems and Progress, 1908-1958,
Hotton, C. S. et al. (ed.). Madison, The University of
Wisconsin Press, 1959. p. 529-538.
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B. GEOGRAPHICAL DISTRIBUTION
There were 380,596 farms in the U.S. in 1969 harvesting
804,850 square kilometers of grain.10 Five states, Illinois,
Iowa, Kansas, Minnesota, and North Dakota (in descending
order), accounted for 40.7% of the total area harvested.
The harvested land area per state (Ag) is illustrated in
Figure 1 and listed in Table 2.
Figure 1.
0- 10,000km2
> 10,000 - 20,000 km2
> 20,000 - 30,000 km2
> 30,000 km?
Area of grain harvested per state
101969 Census of Agriculture; Volume II, General Reports;
Chapter 8, Type of Farm. U.S. Department of Commerce,
Social and Economic Statistics Administration, Bureau of
the Census. U.S. Government Printing Office. Washington
June 1973. 287 p.
111969 Census of Agriculture; Volume V, Special Reports;
Part 1, Grains, Soybeans, Dry Beans, and Dry Peas. U.S.
Department of Commerce, Social and Economic Statistics
Administration, Bureau of the Census. U.S. Government
Printing Office. Washington. Stock No. 0324-00244.
November 1973. 711 p.
10
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Table 2. AREA OF GRAIN HARVESTED PER STATE, 196911
State
Total area harvested (A ), km2
O
Alabama
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Mexico
New York
North Carolina
North Dakota
6,100
1,830
18,880
8,770
14,690
190
1,660
2,450
10,470
7,520
75,410
39,660
74,610
66,260
9,530
7,510
280
4,250
130
14,050
56,330
11,910
32,970
23,250
38,220
140
70
2,390
5,350
12,380
55,110
11
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Table 2 (continued). AREA OF GRAIN HARVESTED PER STATE
State
Total area harvested (Ag), km2
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Nationwide
31,180
23,110
5,160
9,070
20
7,420
36,240
9,250
39,940
1,790
340
5,880
12,220
520
18,350
1,990
804,850
12
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SECTION IV
EMISSIONS
A. SELECTED POLLUTANTS
The emissions from grain harvesting which possess a hazard
potential to public health are respirable (<7 vim) particulates
which contain a free silica fraction.
Particulate matter is one of the criteria pollutants for
which air quality standards exist.12 Those particles with
less than 1% (by weight) free silica are also termed "inert."
The American Conference of Governmental Industrial Hygienists
(ACGIH) has published a threshold limit value (TLV) of
10 mg/m3 for these particles.13 In addition, inhalation of
grain dusts causes a granulomatous reaction in the lungs with
associated interstitial fibrosis. Progressive pulmonary
fibrosis results from repeated exposure.14 This type of
12Code of Federal Regulations, Title 42 - Public Health,
Chapter IV - Environmental Protection Agency, Part 410 -
National Primary and Secondary Ambient Air Quality
Standards, April 28, 1971. 16 p.
13TLVs® Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment with Intended
Changes for 1973. American Conference of Governmental
Industrial Hygienists. Cincinnati. 1973. 94 p.
14Frank, R. C. Farmer's Lung - A Form of Pneumoconiosis Due
to Organic Dusts. The American Journal of Roentgenology.
79^:189-215, February 1958.
13
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reaction is termed farmer's and/or thresher's lung.15 Grain
smuts have been cited as possible causes for the production
of these grain dusts.16 Farmer's lung has been associated
with the long-term inhalation of these smuts.17
Free silica particulate matter has long been associated with
silicosis. This disease results from the prolonged inhala-
tion of these particulates, which produces a pulmonary
fibrosis. Symptoms of the condition may appear after several
years of exposure or after exposure is terminated. Death has
resulted in some cases due to extensive damage to the lung
tissues.18 The TLV for particulates with a free silica con-
tent greater than 1% varies with the percent of free silica
detected.
B. MASS EMISSIONS
The total respirable particulate emission factor for grain
harvesting is a combination of the emission factors from the
following three sources: (1) harvest machine activity,
(2) loading of trucks, and (3) transport on the field.
Emissions data were determined following established proce-
dures (see Appendix C) for each of these activities. The
results of this study are presented in Appendix D.
15Fuller, C. J. Farmer's Lung: A Review of Present
Knowledge. Thorax (London). 8^59-64, 1953.
l6Harris, L. H. The Nature of the Grain Dust Antigen.
Journal of Allergy and Clinical Immunology. 10;433-442,
1939.
17Blaknikova, D., M. Tumova, and A. Valisova. A Syndrome
Resembling Farmer's Lung in Workers Inhaling Spores of
Aspergillus and Penicillin Moulds. Thorax (London).
15^:212-217, 1960.
iSSax, N. I. Dangerous Properties of Industrial Materials,
3rd Edition. New York, Reinhold Book Corp., 1968.
p. 1088-1089.
14
-------
The emission factors (@ 95% confidence level) for respirable
particulates from each of the harvesting operations and the
entire source are listed in Table 3.
Table 3. EMISSION FACTORS FOR RESPIRABLE PARTICULATES
FROM GRAIN HARVESTING
Operation
Machine activity
Loading
Transport
Total respirable
particulate
emission factor
Emission factor (@ 95% level)
Symbol
EM
EL
ETR
ET
Value, g/km2
414
14.7
137.7
566.3
Free silica particulates are emitted from the soil during
the harvest machine activity and transport on the field. The
emission factor for free silica (E ) is 551.6 ± 406.6 g/km2 at
O
the 95% confidence level. (These data are the result of
sampling emissions from the harvesting of two grain crops.)
The total respirable particulate emission factor is used in
computing statewide emission levels. These levels are the
products of the area of grain harvested per state (A ; Table
o
2) and this emission factor. The results are presented in
Table 4 which also lists the state emission burdens.19 These
values are the ratio of each state's respirable particulate
emissions from grain harvesting to the total respirable emis-
sions of that state as reported in the National Emission Data
System, NEDS.19 Respirable emissions are assumed to be about
1/3 of the total reported in NEDS.
191972 National Emissions Report. Environmental Protection
Agency. Research Triangle Park. Publication No.
EPA-450/2-74-012. June 1974. 422 p.
15
-------
Table 4. STATE AND NATIONAL PARTICULATE EMISSIONS BURDENS FROM
THE HARVESTING OF GRAIN19
State
Alabama
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Total
particulates ,
metric ton3
1,178,643
72,685
137,817
1,006,452
201,166
40,074
36,808
226,460
404,574
55,499
1,143,027
748,405
216,493
348,351
546,214
380,551
49,155
494,221
96,160
705,921
266,230
168,355
202,435
272,688
95,338
Respirable
particulates due
to harvesting
of grain,
metric ton9
3.45
1.04
10.69
4.97
8.32
0.11
0.94
1.39
5.93
4.26
42.70
22.5
42.3
37.5
5.4
4.25
0.16
2.41
0.07
7.96
31.9
6.74
18.7
13.2
21.6
Contribution of
harvesting of
grain to overall
state emissions,
%
<0.001
0.004
0.023
0.001
0.012
0.001
0.008
0.002
0.004
0.023
0.011
0.009
0.058
0.032
0.003
0.003
<0.001
0.001
<0.001
0.003
0.036
0.012
0.028
0.014
0.068
1 metric ton = 1 x 106 g = 2,204 Ib.
This value is estimated by taking 1/3 of the state total emissions as
respirable.
16
-------
Table 4 (continued). STATE AND NATIONAL PARTICULATE EMISSIONS
BURDENS FROM THE HARVESTING OF GRAIN19
State
Nevada
New Hampshire
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
TOTAL
Total
particulates,
metric ton3
94,040
14,920
102,785
160,044
481,017
78,778
1,766,056
93,595
169,449
1,810,598
13,073
198,767
52,336
409,704
549,399
71,692
14,587
477,494
161,934
213,715
411,558
75,427
17,872,000°
Respirable
particulates due
to harvesting
of grain,
metric tona
0.08
0.04
1.35
3.03
7.01
31.2
17.7
13.1
2.92
5.14
0.01
4.2
20.5
5.24
22.6
1.0
0.2
3.33
6.92
0.29
10.39
1.13
455.8
Contribution of
harvesting of
grain to overall
state emissions,
%
<0.001
<0.001
0.004
0.006
0.004
0.12
0.003
0.042
0.005
<0.001
<0.001
0.006
0.12
0.004
0.012
0.004
0.004
0.002
0.012
<0.001
0.008
0.004
dl metric ton = 1 x 106 g = 2,204 Ib.
This value is estimated by taking 1/3 of the state total emissions as
respirable.
This total includes five sources not listed by state.
17
-------
The particulate emissions due to harvesting of grain account
for no more than 0.12% in any of the states. The national
emissions burden is 0.008%.
C. DEFINITION OF THE REPRESENTATIVE SOURCE
Emissions due to the harvesting of wheat and sorghum were
chosen to represent those of all grains. These two grains
were reported to have the highest emission factors for a
grain handling activity that generated the greatest amount of
dust.20 In addition, this dust was described as being
primarily composed of particles <5 ym in diameter.21 Using
this basis, the range of emissions due to grain type is
viewed from a "worst case" condition. Therefore, analysis
of different grains is not necessary. This hypothesis was
tested in presurvey, and the results are presented in
Appendix D.
The representative source is derived in Appendix E. It is
defined by arithmetic mean emission parameters for a single
grain crop harvested on a farm. The area of the field har-
vested is 0.44 km2. The distance to the boundary and average
travel distance is 330 m. The population density in the area
surrounding the field is 39.9 persons/km2. This is the
arithmetic mean of the population densities per state.
20 Gorman, P. G. Potential Dust Emissions from a Grain
Elevator in Kansas City, Missouri. Midwest Research
Institute. Kansas City. Fianl report, Environmental
Protection Agency, EPA Contract 68-02-0228, Task 24.
May 1974. p. xv, 52, and 70.
21Epp, D., and M. Schrag. Potential Impact of Emission
Controls on Country Elevators. Midwest Research Institute,
Kansas City, Missouri. MRI Project No. 3866-C. July 24,
1974. p. 43.
18
-------
D. SOURCE SEVERITY
Source severity means and ranges for grain harvesting were
calculated (see Appendix F) for the parameters of the defined
representative source. For criteria pollutants the source
severity was calculated as the time-averaged maximum ground
level concentration (x__v) divided by the national primary
luclX
air quality standard. For noncriteria pollutants x" was
in 3.x
divided by a corrected threshold limit value.
Mean severity for respirable particulates was calculated for
the representative grain field. The severities for each
operation and the entire source are listed in Table 5.
Table 5. MEAN SEVERITIES FOR RESPIRABLE PARTICULATES
Operation
Machine activity
Loading
Transport
Time-weighted total
severity
Mean severity
11.2 x ICr4
3.0 x 10~5
1.7 x 10~2
3.5 x 10-3
The mean severity for free silica particles generated from
the machine activity and transport was calculated as being
-------
distribution is presented in Figure 2. The distribution is
near normal, with a maximum of 0.32 and a mean (for 50% of
the grain fields) at 0.28, which is within 4% of the value
(0.29) calculated for the representative source. The deri-
vation of this distribution is presented in Appendix F.
0.24
0.25 0.26
0.27 0.28 0.29
SOURCE SEVERITY
0.30
0.31 0.32
Figure 2. Source severity distribution for free silica
20
-------
SECTION V
CONTROL TECHNOLOGY
A. STATE OF THE ART
There are no control techniques specifically implemented
for the reduction of air pollution emissions from grain
harvesting. However, several practices and occurrences
inadvertently affect emission rates and concentrations.
The use of terraces, contouring, and stripcropping to
inhibit soil erosion22 also suppresses the entrainment of
harvested crop fragments in the wind. Shelterbelts, posi-
tioned perpendicular to the prevailing wind, also lower
emissions by reducing the wind velocity across the field.
An average shelterbelt can reduce the wind velocity by more
than 10% up to a distance of 20 times the tree height on the
downwind side and three times on the upwind side of the
field.5 Lower wind speeds and stable atmospheres reduce
emission rates but increase concentrations as evidenced by
dispersion equations.23 In addition, by minimizing tillaging
22Allaway, W. H. Systems - Cropping Systems and Soil. In:
The Yearbook of Agriculture 1957. U.S. Government Printing
Office. Washington, 1957. p. 393.
23Turner, D. B. Workbook of Atmospheric Dispersion Estimates.
U.S. Department of Health, Education, and Welfare.
Cincinnati. Public Health Service Publication No. 999-AP-26,
May 1970. 65 p.
21
-------
and avoiding residue burning, the soil will remain consoli-
dated and less prone to emission from transport activities.
Sexual sterility can be induced in insects and weeds by the
use of attractants and pathogens, thereby eliminating the
need for pesticides and thus the pesticide residues on crop
fragments.24
B. FUTURE CONSIDERATIONS
Control of atmospheric emissions centers around two areas:
(1) modification of the harvesting machine activity, and
(2) alteration of the crop characteristics.
In the machine harvest of grain crops, kernel breakage is a
factor in the creation of dust and the reduction of grain
quality. Breakage is greatest at low temperatures and
moisture contents. Harvesting the crops at higher tempera-
tures and moisture contents will therefore reduce the dust
levels and enhance the quality of the grain. This approach,
however, contradicts the recommendations for storing grain.25
Water application at the time of harvest is a possibility for
curtailing dust generation, but the feasibility of maintaining
a water supply on the harvest machine is questionable.
Application of water prior to or during the harvest also
presents a problem termed "weathering" which refers to the
24 New Approaches to Pest Control and Eradication. Advances
in Chemistry Series, No. 41. Washington, American Chemical
Society, 1963. 74 p.
25Fiscus, D. E., G. H. Foster, and H. H. Kaufmann. Physical
Damage of Grain Caused by Various Handling Techniques.
Presented at the 1969 Winter Meeting of the American
Society of Agricultural Engineers, Sherman House, Chicago.
Paper No. 69-853. St. Joseph, Michigan, American Society
of Agricultural Engineers, December 1969. 25 p.
22
-------
partial digestion of the starch and increase of mold growth
caused by the higher moisture levels. In addition, farmers
are penalized if the moisture content of grain is too high.
Reduction of the free fall (drop height) and abrasiveness of
contacted surfaces within the harvest machine will reduce the
fragmentation of the grain crop. Addition of a baghouse/
screening type of collector, as an integral component of the
harvest machine, could collect particulate emissions. An
aspiration system would be required to entrain dust at the
points of emission.
All of the above techniques require design modifications of
the harvest machines.
Covering the entire crop field in a controlled environment
has been suggested as a possible means of control. The
confidence in this approach for vegetables and fruits is
greater than for large areas of grain. However, a controlled
environment requires only 2% of the water used for open
cultivation. Since the enclosure keeps out pests and the
soil is easily sterilized, there is little or no requirement
for pesticides. Soil erosion problems are also eliminated,
and the area required for grain plant production could be
reduced by a factor greater than 10.26 However, the feasi-
bility and practicality of such crop alteration from an
economic and technical standpoint are highly uncertain.
26Taylor, T. B., et al. A Systems Approach to Problem
Oriented Research Planning: A Case Study of Food
Production Wastes. International Research and Technology
Corp. IRT No. 244-R (PB 228 114). June 1973. 105 p.
23
-------
SECTION VI
GROWTH AND NATURE OF THE INDUSTRY
A.
PRESENT TECHNOLOGY
An increase in the use and efficiency of mechanical equip-
ment in harvesting grain crops has brought about many changes
in recent years. This machinery has enabled production of
grain to keep up with demand and has allowed a profitable
return in the face of rising farming costs. The number of
each type of machine utilized is listed in Table 6.27
Table 6. HARVESTING MACHINES UTILIZED27
Type
Pickup balers
Cornpickers, cornheads,
and picker-shellers
Grain and bean combines
Number
708,044
634,592
467,226
Percent of total
39.1
35.1
25.8
The combine is the most widely accepted machine in all
sections of the U.S.28 Combines are often used for the
27 1969 Census of Agriculture; Volume V, Special Reports;
Part 15, Graphic Summary. U.S. Department of Commerce,
Social and Economic Statistics Administration, Bureau of
the Census. U.S. Government Printing Office. Washington.
Stock No. 0324-00252. December 1973. 145 p.
28 Encyclopaedia Brittanica, 1974 Edition. Volume 5 -
Cereals and Other Starches. Chicago, Encyclopaedia
Brittanica, Inc., 1974. p. 1161.
24
-------
"windrow and pickup" method which facilitates the harvesting
of weedy, moist, and/or unevenly ripening crops. However,
this method is more expensive than direct combining.^
Most farms are equipped with mechanical pickers for har-
vesting corn. These machines, available in the one or two
row variety, pick and husk the crop. Manual picking and/or
husking is performed in some areas, but the cost is much
higher. Therefore, an increasing area of corn is mechani-
cally harvested.
The rapid growth of this mechanization has increased the
production of grain crops in the Western States where the
combine has been especially popular. The development of the
windrow method has also caused growing use of the combine in
the East.4
B. EMERGING TECHNOLOGY
No specific technological breakthroughs are anticipated in
the grain harvesting industry, although the future promises
a steady improvement in harvest machine design and adapta-
bility. Better cultivation practices, improved crop varie-
ties, control of pests, maintenance of soil productivity,
and economical labor will further accelerate grain production,
C. TRENDS
The number of persons supported by the production of one
farm worker has grown from four in 1820 to 39 in 1966.29
Mechanization has made this increase possible. With the
29 Kendall, J. R., et al. Agricultural Statistics. U.S.
Department of Agriculture. U.S. Government Printing
Office. Washington, 1967. p. 526, 528, 539, and 549.
25
-------
increased use of machinery comes a decrease in the number
and an increase in the size of farms.
The population of the U.S. will continue to increase, and
improvements in current cropland harvested and yields per
square kilometer will be necessary. This will require
rising efficiency, specialization, and heavy capital outlay
for farm operations. Greater demands for grain exports will
further advance the area of land harvested. Production will
grow at the rate of 2% per year; by 1978 the total area
harvested is expected to reach 909,480 km2.30
30Shannon, Y. J., R. W. Gerstle, P. G. Gorman, D. M. Epp,
T. W. Devitt and R. Amick. Emissions Control in the
Grain and Feed Industry, Volume I - Engineering and Cost
Study. Midwest Research Institute, Kansas City, Missouri.
Environmental Protection Agency, EPA-450/3-73-003a
(PB229-996). December 1973. p. 4-14.
26
-------
SECTION VII
UNUSUAL RESULTS
The fact that the free silica content of the particulate
collected originated from the soil was unexpected. The
silica content of the soil is three orders of magnitude
greater than that of the grain. By visual observation, the
harvesting machine was not in contact with the ground except
for the tires. The source of the free silica had to be
either the soil from the ground or soil particles that ad-
hered to the grain plant. It had rained prior to the day
on which the airborne particulate was collected, thereby
suppressing the ground soil. It is therefore believed that
the free silica emanated from soil particles adhering to the
grain plant.
Appendix G presents the maximum pollutant concentration values
from the source.
27
-------
SECTION VIII
APPENDIXES
A. Calculation of Pesticide Residue Concentration Downwind
of Harvesting Activity
B. A Method for Estimating TLV Values for Compounds where
None Exist
C. Sampling Methodology - Analysis and Procedures
D. Sampling Results
E. Derivation of the Representative Source
F. Calculation of Source Severity
G. Determination of Maximum Pollutant Concentrations
28
-------
APPENDIX A
CALCULATION OF PESTICIDE RESIDUE CONCENTRATION
DOWNWIND OF HARVESTING ACTIVITY
The pesticide levels downwind of the machine harvesting
activity were calculated for two selected pesticide residues.
These residues were detected on grain plants just prior to
harvest. One has the lowest TLV and the other the highest
concentration in the plant (see Table A-l) (some pesticides
in Table A-l are no longer used, but do not deteriorate easily
in the environment and are included here for calculation
purposes).31/32
The lowest TLV for the pesticide residues detected is that of
Endrin, 0.1 mg/m3. The concentration of this residue detected
on the grain plants is <0.01 ppm. This is equated to 0.01 ppm.
Applying an increase of three orders of magnitude, this
becomes a concentration of 10 ppm (by weight) in the dust.
The weighted mean emission rate for harvesting is
/
9.8 ± 7.4 mg/s at the 95% confidence level (Appendix D).
Using the point source model23 for average U.S. conditions
3 Crockett, A. B., G. B. Wiersana, H. Tai, W. G. Mitchell,
P. F. Sand, and A. E. Carey. Pesticide Residue Levels in
Soils and Crops, FY-70 - National Soils Monitoring Program.
Pesticides Monitoring Journal. 8J2):96-97, September 1974.
32Carey, A. E., G. B. Wiersana, H. Tai, and W. G. Mitchell.
Organochlorine Pesticide Residues in Soils and Crops of
the Corn Belt Region, United States - 1970. Pesticides
Monitoring Journal. £(4):375, March 1973.
29
-------
Table A-l. LIST OF TLV'S AND CONCENTRATION OF
PESTICIDE RESIDUES ON GRAIN PLANTS31'32
Pesticide
Dieldrin
Endrin
Ethion
Chlordane
f
0, p1 - DDE
p, p1 - DDE
o, p' - DDT9
p, p1 - DDT
h
DDTR
Heptachlor
Heptachlor Epoxide
i
p, p' - TDE
Toxaphene
Malathion
Ethyl Parathion
PCB ' sj
Ramrod
Trifluralin
Lindane
Aldrin
TLV,
Q
mg/irr
0.253
a
0.10
b
0.14
a
0.50
e
N.A.
N.A.
1.0
1.0
N.A.
a
0.5
b
0.64
N.A.
a
0.5
a
10
N.A.
0.5
b
5.92U
N.A.
0.5
0.25a
Mean concentration, ppm (by weight)
Group A
Soybean
beans
0.01
<0.01
-
<0.01
—
-
0.012
0.015
-
<0.01
<0.01
-
0.02
-
-
_
<0.01
<0.01
0.005
0.001
Group B
Corn
kernels
<0.01
<0.01
<0.01
-
—
-
-
-
-
-
-
-
-
—
-
^
—
-
-
-
Corn
stalks
<0.01
d
-
0.01
<0.01
<0.01
0.01
0.03
0.04
<0.01
<0.01
<0.01
0.02
<0.01
<0.01
2.8
-
-
-
-
Grain
sorghum
ND°
-
-
-
—
ND
ND
ND
ND
-
ND
ND
-
-
ND
ND
—
-
-
-
Sorghum
forage
0.01
-
-
-
—
ND
ND
ND
ND
-
ND
ND
-
-
ND
ND
—
-
-
-
Skin TLV.
Converted from "jD5o to TLV
(see Appendix B);
TLV = 0.0198 (LD50)°-771t.
"None detected.
Dashes indicate that analyses
were not completed for the
specific pesticide shown.
3
"N.A. = not available.
DDE = Dichlorodiphenyl
dichloroethylene.
3DDT = l,l,l-Trichloro-2,2-
bis(p-chlorophenyl)ethane,
DDTR = DDE + TDE.
TDE = l,l-Dichloro-2,2-
bis(p-chlorophenyl)ethane.
= Polychlorinated
biphenyls.
30
-------
(stability C, wind speed 4.5 m/s), the concentration for a
ground level source at 10 m downwind is 443 yg/m3. With the
pesticide residue constituting 0.001% by weight (10 ppm of
the dust), the concentration is 0.0044 pg/m3. This is five
orders of magnitude less than the TLV value of 0.1 mg"/m3.
The same process was followed for the highest concentration
of pesticide residue detected (Table A-l), 2.8 ppm for PCB's,
Applying an increase of three orders of magnitude, the con-
centration is 2,800 ppm (by weight) in the dust. Using the
ground level point source model at average U.S. conditions,
the downwind concentration at 100 m is four orders of magni-
tude less than the TLV of 0.5 mg/m3 for PCB's. Therefore,
for the lowest TLV and highest concentrations of pesticide
residues found on grain plants, the downwind concentrations
are at least four orders of magnitude less than their TLV's
at 100 m from the source.
31
-------
APPENDIX B
A METHOD FOR ESTIMATING TLV VALUES
FOR COMPOUNDS WHERE NONE EXIST
by J. A. Peters
Monsanto Research Corporation
In assessing health hazards associated with the application
of agricultural chemicals, many of the emitted compounds to
be assessed have no TLV assigned by the ACGIH. The TLV of
air pollutants is utilized as an integral part of Industrial
Environmental Research Laboratory's first decision criteria
for future control technology development.
Thirty agricultural chemicals selected from those listed in
Reference 13 with their TLV values are shown in Table B-l.
Seven of the 30 chemicals are herbicides, one is a fungicide,
and 22 are insecticides; no distinction is made between
inhalation and skin TLV. The most common toxicity value
published for chemical substances is the acute oral LD50
dose for male rats.33'34 These LD50 values are tabulated
with the TLV's and curve-fitting is attempted to correlate
LD50 with TLV to obtain a relationship whereby compounds of
unknown TLV can be assigned functional TLV's for decision
criteria use. The results of the best curve-fit are
presented below.
331969 Farm Chemicals Handbook. Willoughby, Ohio, Meister
Publishing Co., 1968. 472 p.
3l+Toxic Substances List, 1972 Edition. John J. Thompson
and Co. Rockville, Maryland. June 1972. 563 p.
32
-------
Table B-l. SELECTED AGRICULTURAL CHEMICALS
1 3
Chemical (primary use)
Abate (insecticide)
Aldrin (insecticide)
Allyl Alcohol (herbicide)
Animate (herbicide)
Arsenic Acid (herbicide)
Carbaryl (Sevin®) (insecticide)
Chlordane (insecticide)
Toxaphene (insecticide)
2,4-D (herbicide)9
DDT (insecticide) "
DDVP (insecticide)0
Demeton (insecticide)
Diazinon (insecticide)
Dibrom (insecticide)
Dieldrin (insecticide)
Dinitro-o-cresol (insecticide)
Diquat (herbicide)
Endrin (insecticide)
EPN (insecticide) d
Heptachlor (insecticide)
Malathion (insecticide)
Methoxychlor (insecticide)
Methylparathion (insecticide)
Paraquat (herbicide)
Parathion (insecticide)
Phosdrin (insecticide)
Ronnel (insecticide)
2,4,5-T (herbicide)6
TEPP (insecticide) >
Thiram (fungicide)
TLV,
mg/m3
10
0.25
3
10
0.5
5
0.5
0.5
10
1
1
0.1
0.1
3
0.25
0.2
0.5
0.1
0.5
0.5
10
10
0.2
0.5
0.1
0.1
10
10
0.05
5
LD 5 o , mg/kg
(acute oral
rat dose)
2000
55
95
3900
48
500
570
69
1200
113
56
9
134
430
60
50
300
5
50
90
1375
5000
25
145
15
7
1740
500
1.2
860
2,4-D = 2,4-Dichlorophenoxyacetic acid.
DDT = 1,1,l-Trichloro-2,2-bis(p-chlorophenyl)ethane.
CDDVP = Dimethyl 2,2-dichlorovinyl phosphate.
EPN = O-Ethyl O-p-Nitrophenyl phenylphosphonothioate.
2,4,5-T = 2,4,5-Trichlorophenoxyacetic acid.
TEPP = Tetraethyl pyrophosphate.
33
-------
The best APL regression fit is an equation of the type:
y = axb (B-l)
Logarithmic transformation of Equation B-l yields:
In y = In a + b In x (B-2)
Equation B-2 is further transformed to resemble the familiar
straight-line slope-intercept equation form:
Y = MX + B (B-3)
if Y = In y
B = In a
M = b
X = In x
The indicators of goodness-of-fit for this regression show
that R2 = 0.7951 and the F-value = 108.6.
The fitted values for the slope-intercept form are:
B = -3.921
M = 0.774
Standard errors are computed and result in:
SM = 0.07426 = standard error of M (slope)
S „ = 0.821 = standard error of estimate
S., = 0.3936 = standard error of B (intercept)
£>
Programming language.
34
-------
S_, is calculated separately where
B
E (Transformed x.)2
"R Y • V W
' n £ (Transformed x. - mean transformed x.)
Using the above calculated values, 95% confidence level
intervals are obtained about the slope and intercept of the
b
equation y = ax :
Slope
b (or M) ± Z S,, gives the upper and lower bound
a/2 M r
limits for the confidence interval. Given n = 30,
a = 0.05 so Z = 1.96; then 0.774 ± (1.96)(0.07426)
a/2
will be (0.6285 <_ slope <_ 0.9195) = 95%. The slope
confidence interval is the same in transformed space
as in the original space.
Intercept
In transformed space the 95% confidence interval is
B ± Z S_; but in the original space:
a/2 B
anti ln
which is -soQ < intercept < (0 . 01982) (2 . 1629)
2 . ±b/y
or (0.00916 1 0.0198 £ 0.04287) = 95%
In the Y = MX + B equation form, the 95% confidence limits
for B are ± 19.7% of B, and for M are ± 18.8% of M. In
original space, the exponential equation form y = ax , the
limits for b are the same as those for M, but the confidence
limits for a become + 216.5% and -46.3%. Dividing the
maximum value by the minimum value for the 95% confidence
interval yields 4.68 for a and 1.46 for b.
35
-------
The final form of the regressed equation relating LD50 to
TLV, given the original (LD50» TLV) pairs, is:
TLV = 0.0198(LD50) °'77it (B-4)
where LD50 = acute oral dose, mg/kg, for male rat
TLV = threshold limit value, mg/m3
The TLV values for the pesticides listed in Table A-l
(Appendix A) were calculated using Equation B-4.
36
-------
APPENDIX C
SAMPLING METHODOLOGY - ANALYSIS AND PROCEDURES
1. INSTRUMENTATION
The GCA® Model RDM 101-4 respirable dust monitor3 was used
to sample the downwind concentration of respirable particu-
lates from the harvesting of wheat and sorghum. This is an
advanced instrument designed for on-the-spot measurements
of mass concentrations of the respirable fraction or the
total mass loading of particulates. It is a portable and
fully self-contained monitor with automatic and direct
digital readout of the mass concentration of airborne parti-
culates. Readings can be taken for from 4 minutes to
30 minutes sampling time, and a traverse of points around a
source of interest can be accomplished quickly.
Results are obtained by electronic measurement of the beta
absorption of the collected sample. A cyclone collection
system is used as a first stage for respirable (<10 ym)
measurements. Using the respirable concentration values
obtained with the GCA, the emission rate of particulates can
be obtained through use of the appropriate model.35
GCA Corporation
GCA/Technology Division
Bedford, Massachusetts 01730
35Lilienfeld, P., and J. Dulchinos. Portable Instantaneous
Mass Monitor for Coal Mine Dust. American Industrial
Hygiene Association Journal. 33^:136, March 1972.
37
-------
2.
MODELS
Open source sampling uses diffusion models in reverse.
Normal use is to predict concentrations surrounding a point
source of known strength. Several concentration readings
are taken to calculate the source strength of an open source.
Models applicable to the sampling arrangement and source
characteristics are chosen and utilized for each source of
emissions. For grain harvesting there are three sources;
(1) harvest machine activity, (2) loading the truck, and
(3) truck transport on the field.
Two models are used in this study. The first represents
emissions from machine activity and loading operations.
23
This is the point source model * where:
z;
exp
[-i^Yl
[2( °,)\
+ exp
n
iz
1
(C-l)
The notation used to depict the concentration is x(xfY/z;H)-
H, the height of the plume centerline from the ground level
when it becomes essentially level, is the sum of the physical
stack height, h, and the plume rise, AH. The following
assumptions are made: the plume spread has a Gaussian dis-
tribution in both the horizontal and vertical planes, with
standard deviations of plume concentration distribution in
the horizontal and vertical of o and o , respectively; the
mean wind speed affecting the plume is u; the uniform emis-
sion rate of pollutants is Q; and total reflection of the
plume takes place at the earth's surface, i.e., there is no
deposition or reaction at the surface. Any consistent set
of units may be used. The most common is x in 9/m3/ Q in
g/s, u in m/s, and a
,
H, x, y, and z in meters.
38
The
-------
concentration \ is a mean over the same time interval as the
time interval for which the a's and u are representative.
The values of both a and a are evaluated in terms of the
downwind distance, x, and stability class. Stability classes
are determined conveniently by graphical methods, Figure
C-l.36 Continuous functions are then used to calculate
values for a , and a , Tables C-l37 and C-2,38 given the down
wind distance, x. In open source sampling the sampler is
maintained in the center of the plume at a constant distance;
the plume has no effective height (H=0); and the concentra-
tions are calculated at ground level. Equation C-l thus
reduces to:23
* (x' °' 0; 0) = 1^1 (C~2)
The second model is used to describe emissions from transport
on the field. In this equation instantaneous puff concentra-
tions are represented by Equation C-3:39
2X1/2 QD
* = U
36Blackwood, T. R., T. F. Boyle, T. L. Peltier, E. C. Eimutis,
and D. L. Zanders. Fugitive Dust from Mining Operations.
Monsanto Research Corporation. Dayton. Report No.
MRC-DA-442. (EPA Contract 68-02-1320, Task 6.) May 1975.
p. 34.
37Eimutis, E. C., and M. G. Konicek. Derivations of
Continuous Functions for the Lateral and Vertical
Atmospheric Dispersion Coefficients. Atmospheric
Environment. 6^:859-863, March 1972.
38Martin, D. 0., and Tikvart, J. A. A General Atmospheric
Diffusion Model for Estimating the Effects on Air Quality
of One or More Sources. (Presented at the 61st Annual Meet-
ing of the Air Pollution Control Association. St. Paul.
June 23-27, 1968.) 18 p.
39Gifford, F. A., Jr. Chapter 3 - An Outline of Theories of
Diffusion in the Lower Layers of the Atmosphere. In: Mete-
orology and Atomic Energy 1968, Slade, D. A. (ed.). Oak
Ridge, Tennessee, U.S. Atomic Energy Commission Technical
Information Center. Publication No. TID-24190. July 1968.
p. 445.
39
-------
ID
m
C
O
•H
4J
(0
C
•H
g
H
-l
Q)
CQ
O
M-l
O
o
U
(1)
40
-------
Table C-l. CONTINUOUS FUNCTION FOR LATERAL
ATMOSPHERIC DIFFUSION COEFFICIENT o 37
a = AX0.9031
Stability class
A
B
C
D
E
F
A
0.3658
0.2751
0.2089
0.1471
0.1046
0.0722
Table C-2. CONTINUOUS FUNCTION FOR VERTICAL
ATMOSPHERIC DIFFUSION COEFFICIENT a
38
AX
B
Usable range
>1000 m
100 - 1000 m
<100 m
Stability
class
A
B
C
D
E
F
A
B
C
D
E
F
A
B
C
D
E
F
Coefficient
AI
0.00024
0.055
0.113
1.26
6.73
18.05
A2
0.0015
0.028
0.113
0.222
0.211
0.086
A3
0.192
0.156
0.116
0.079
0.063
0.053
BI
2.094
1.098
0.911
0.516
0.305
0.18
B2
1.941
1.149
0.911
0.725
0.678
0.74
B3
0.936
0.922
0.905
0.881
0.871
0.814
Ci
-9.6
2.0
0.0
-13
-34
-48.6
C2
9.27
3.3
0.0
-1.7
-1.3
-0.35
41
-------
where ty = dose, g-s/nv3
QD = line source emissions per length of line, g/m
a = instantaneous vertical dispersion parameter, m
u = mean wind speed, m/s
For neutral stability:
azl = 0.15 xc°-7 (C-4)
where x_ = crosswind distance from the line source, m
Equation C-3 is a line source diffusion model and is used to
find the mass emissions per length of road. The value of
the dose, \i>, is determined by multiplying the concentration
by the actual sampling time.
3. DATA COLLECTION
Each variable for these models was determined in the field
by use of the sampling arrangement shown in Figure C-2. For
each concentration reading, displayed by direct digital
readout, the mean wind speed was determined by averaging
15-s readings (a stopwatch was used) of the wind meter.
This meter is connected to the anemometer which sits atop a
3.05-m (10-ft) pole. Distance x was measured by visual
observation of the number of combine swaths downwind of the
source. The 6.1-m (20-ft) wide swaths could be counted by
the rows of threshed grain stalks left on the field.
All these data were recorded for each sampling run on the
form shown in Figure C-3 while in the field. The time of
day and atmospheric stability (determined following Figure
C-l) were recorded periodically on the bottom of the form.
42
-------
ANEMOMETER
HOUSING
ANEMOMETER
WEATHER POLE
CLIPBOARD
WIND METER
CYCLONE SEPARATOR
RESPIRABLEDUST
MONITOR
SAMPLING PLATFORM
STOPWATCH
TRIPOD STAND
Figure C-2. Sampling apparatus
43
-------
O
C£.
•=>
O
O
O
O en
c/E
07?-
O
O =3.
Q .E
K E
t M
LU"
O
>~
>—i CM ro
n ii n
O
Q-
-
<£
O
M
O
(0
4J
(0
Q)
•tH
ro
I
U
0)
44
-------
The terms used on the field data form are explained below.
Table C-3. EXPLANATION OF FIELD DATA FORM TERMS
Term (units)
Read (mg/m3)
Cone, (yg/m3)
R/T
BCD (yg/m3)
A (yg/m3)
Q (g or g/sec)
S1
M
Meaning
Concentration reading
Converted concentration for sampling
times greater than 4 minutes
(lower right hand corner).
R = respirable reading
T = total mass reading
Background concentration
The difference between the converted
concentration and the background
Calculated emission rate
Stability for the time of day the
unit operation was sampled
The model used referenced as 1, 2,
or 3 (point, line, or dose,
respectively)
Any factors that might have affected concentration or emis-
sion rate were mentioned in the column labeled "Comments."
When this form was completed the data were programmed into a
computer and the emission rate, Q, calculated in accordance
with the model specified in the column labeled "M."
4.
PROCEDURES
a. Harvest Machine Activity
The harvest machine is a mobile source which travels along a
line. The original intent was to sample this source from a
stationary position (using the arrangement in Figure C-l)
and apply a line source model. However, while sampling in
the field the concentration was undetectable with this
method. The speed of the combine (9.65 km/hr) and length of
45
-------
the field (^3.2 km) caused the instrument to remain in the
plume for only 10 s to 15 s. The actual sampling time of
the GCA is 3 minutes 40 seconds for a 4-minute run. The
remaining 20 seconds is devoted to initial and final beta
counts.35 The instrument was thus in the plume only 4.5% to
6.8% of the time. The remaining time was spent sampling
background concentration levels. This caused dilution of
the 10-s to 15-s sample and resulted in undetectable
concentrations.
The solution to the problem was to keep the monitor in the
plume centerline by carrying it alongside the combine. This
was possible because the instrument was portable and the
plume was visible. The sampling platform (Figure C-2) was
removed from the tripod and the anemometer connected, minus
pole, to the platform. In this manner wind speed was deter-
mined while walking alongside the combine.
Concentration readings were immediately obtained using this
technique, and they were all within the same order of magni-
tude. The combine thus became a continuous point source,
and the model represented by Equation C-l was used to
calculate the emission rate.
b. Loading the Truck
The sampling platform was returned to the tripod for
measurement of the emissions from the loading of trucks with
grain kernels. It was possible to stay at a fixed downwind
position and remain in the centerline of the plume from this
operation. The point source model. Equation C-2, was there-
fore used to describe the emissions, and sampling procedures
described above were followed.
46
-------
c. Transport on the Field
The platform had to be left on the tripod for sampling the
emissions from transport on unpaved roads. This is a mobile
line source similar to the combine, but the faster truck
speed (16.1 to 32.2 km/hr) did not allow walking alongside
the source. After a few undetectable readings were obtained
at a stationary position, it became evident that the monitor
was not in the plume long enough to capture a measureable
amount of particulate, given the 4-minute sampling time. In
order to provide a sufficient capture time, the truck was
driven back and forth upwind of the sampler. The number of
passes and speed of the truck were recorded on the sampling
form (Figure C-3). Markers were placed along the road to
assure travel of a constant back and forth distance.
This procedure involved starting the sampler, walking to the
truck, and driving back and forth between the markers for 4
to 5 minutes. The time it took to walk to the truck did not
dilute the sampling results because the initial beta count
was occurring during this time. Using this method the instru-
ment periodically received short-term releases of particulates,
The Equation C-2 model was therefore used. Emission rates
from this model are divided by the number of passes of the
vehicle to yield the emission rate per vehicle pass.
5. ANALYSIS
The composition of the particulate was determined using the
Bendix Model 150 Telmatic Air Sampler. This unit consists
of a pump, charcoal filter, and tubing connected to a
cassette encasing a Millipore® filter.9 The sampler is
3Millipore Corp., Bedford, Massachusetts,
47
-------
battery operated, portable, and can be preset to run up to
an hour, or continuously (depending on battery-life). During
sampling the unit is set to run continuously while the GCA
sampling of the source proceeds. The starting time and flow
rate of the unit are recorded on the form shown in Figure C-4.
Pertinent data are obtained and recorded in the same manner
as with the GCA instrument. At the end of the sampling
period, time and flow rate are again recorded. An average
flow rate is then determined, along with estimates of the
mean wind speed and distance from the source. The filter is
then weighed and ashed in the laboratory. Analysis is
performed by infrared spectrophotometry to determine the free
silica content.40 It is assumed that this free silica is all
respirable dust.
A sampling time of 3 hr to 5 hr is required to obtain an
adequate particulate collection for analysis. A sample was
taken downwind of the combine activity in the field. Samples
could not be taken of the loading or transport activities due
to their short operating durations. In addition, if the
magnitude of free silica emissions from the combine activity
were found to be low there would be no need to sample the
grain loading activity. Therefore, this initial analysis did
not require sampling these operations.
^Cares, J. W., A. S. Goldin, J. J. Lynch, and W. A. Burgers
The Determination of Quartz in Airborne Respirable Granite
Dust by Infrared Spectrophotometry. American Industrial
Hygiene Association Journal. 34^298-305, July 1973.
48
-------
in
U I
s
o
0
LU
O
O
LU
t—
Q
LU
CO
O 5 5
>O D-
Q_ LU
s s
I'i
r> LU
11
LJ_ —
h—
o: LU
• CO
S <
t M
O
1 —
CO
/""^ ^^
0 S'a:
2 Lu i
~Z Q- S
S CO
LU
Q_
g
CO
LU
I —
CO
LU
4J
- =}
49
-------
APPENDIX D
SAMPLING RESULTS
1. EMISSION RATES
The total emission rate from grain harvesting is a composite
of the emission rates from each of the harvesting activities.
However, each of these activities takes a different length
of time. This fact will be reflected in the total emission
rate by weighting each of the emission rates by its duration.
The reference or common denominator time used is the time
required to harvest and load a truck-full of grain.
The average amount of grain loaded onto a truck, GT , is
Jj
8,691 kg.41 In Table D-l it can be seen that grain has an
average weight per volume, W , of 664 kg/m3 and an average
volume per area, V_., of 303 m3/km2.42 Therefore, a truck
(j
carrying a load of 8,691 kg represents the harvest of an
area, AH, calculated in Equations D-l and D-2 :
(G )
A = _ (D-l)
-------
Table D-l.
AVERAGE GRAIN WEIGHT PER VOLUME
AND VOLUME PER AREA
Grain
Wheat
Rye
Oats
Corn
Barley
Grain sorghum
Soybeans
Flaxseed
Arithmetic mean
WG, kg/m3
773
683
399
657
580
722
773
722
664
VQ, m3/km2
216
164
381
623
329
415
208
86
303
The time required to harvest this area (Au) is calculated
n
from the speed and swath width of the harvest machine. These
machines operate at speeds up to 6.71 m/s,43 with the mean,
H~s, assumed to be 3.36 m/s. The average swath width, £5, of
a combine is 6.07 m. Using Equation D-3:
TS =
'l x 106 m2
km
km
hr
(Hs)j
3,600 sec
(D-3)
the time to harvest 1 km2, T , is calculated in Equation D-3
o
as 13.62 hr/km2. The time required to harvest the 0.043 km2
area, Tu, is then calculated from Equation D-4 as 0.59.
n
T = T • A
H S H
(D-4)
In addition, the time required to load this grain onto the
truck, TT, is approximately 6 minutes. The composite time
^Zimmerman, M. D. Field-Going Factories: Agricultures'
Amazing Monster Machines. Machine Design. 47(20):16-22,
August 1975.
51
-------
required to harvest and load a truck full of grain, T™, is
calculated in Equation D-5:
T = TH + TL = 0.69 hr (D-5)
The weighted emission rates can thus be calculated for each
of the harvesting activities using this time reference.
The emission rate for the machine harvesting activity, QH, is
calculated from the sampling results for wheat and sorghum
harvesting presented in Tables D-2 and D-3. (The original
data sheets and computer printouts are located in Appendix H),
Combining these tables, the arithmetic mean emission rate is
8.38 ± 7.0 mg/s at the 95% confidence level. However, an
F-test of these tables shows that the ratio of the variances
for emission rates for wheat and sorghum harvesting are non-
homogeneous. This illustrates the fact that the grain type
is not a critical factor.
Table D-2. EMISSION RATES FROM WHEAT
HARVESTING MACHINE ACTIVITY
Emission rates, g/s
3.969 x 10~3 3.696 x 10~3
8.353 x 10~3 4.859 x 10~3
6.776 x 10~3 3.031 x 10~3
2.582 x 10~3 3.689 x 10~3
2.129 x 10~3 2.578 x 10~3
2.346 x 10~3 4.653 x 10~3
2.460 x 10~3 1.801 x 10~3
3.760 x 10~3 1.091 x 10~3
1.620 x 10~3 2.082 x 10~3
The emission rate for loading of the trucks, Q_, is the
L
arithmetic mean of two values obtained during sampling,
52
-------
Table D-3. EMISSION RATES FROM SORGHUM
HARVESTING MACHINE ACTIVITY
Emission rates, g/s
4.552 x 10~3
6.411 x 10~3
1.941 x 10~2
3.571 x 10~3
2.162 x 10~2
8.406 x 10~2
1.692 x 10~3 g/s and 1.819 x 10~3 g/s. This value is
1.76 ± 0.8 mg/s at the 95% confidence level.
The emission rate for the transport of the harvested crop on
a field was determined with the results presented in Table
D-4. These values were all obtained at a downwind distance
of 18 m. Four values were obtained at vehicle speeds of
4.47 m/s and four values at 8.94 m/s. Thus the arithmetic
mean emission rate of 0.009 ± 0.004 g/veh-m at the 95% con-
fidence level, used to calculate the emission rate per time
period was obtained over these two values of vehicle speed.
At 4.47 m/s, the rate was 0.005 ± 0.001 g/veh-m, and at
8.94 m/s, it was 0.012 ± 0.005 g/veh-m, illustrating that
emission rate varies with vehicle speed.
Table D-4. EMISSION RATES, TRANSPORT ON THE FIELD
Vehicle
speed,
m/s
4.47
8.94
4.47
8.94
4.47
8.94
4.47
8.94
Wind
speed,
m/s
4.1
6.3
3.6
4.5
5.9
4.5
5.9
7.2
Concentration ,
yg/m3
30
40
30
90
20
160
40
50
Travel
distance,
m
293
475
293
439
329
439
402
329
Emission
rate,
g/veh-m
0.005
0.006
0.004
0.011
0.004
0.019
0.007
0.012
53
-------
During the harvesting of the 0.043 km2 reference ares, the
distance traveled, D , is twice (round trip) the representa-
tive distance, D, calculated in Appendix E, or 660 m. The
vehicle travels this distance during the 0.69 hr (T ) required
to harvest and load the next truck. The mean speed a truck
travels on the field lies between 2.4 m/s and 6/71 m/s, with
a mean speed, V , of 4.48 m/s chosen. The time required to
ID
transport (TmTD) the grain the distance on the field (Dm) is
IK 1
calculated from Equation D-6.
DT
TTR = ^ (D-6)
D
= 660 m/(4.48 m/s) = 125 s = 0.035 hr
The time-based emission rate for transport is calculated in
Equation D-7.
- ,0.009 g/veh-n,(660 M, ^- (D-7)
= 47 ± 20.7 mg/s at the 95% confidence level
The weighted emission rate for each of the harvesting activi-
ties is calculated from the product of each emission rate and
the ratio of time required to perform the activity and com-
posite time, TT. These values are tabulated and calculated
in Table D-5. The composite emission rate, Q , is thus the
sum of the composite ratio for each activity and is calculated
in Equation D-8.
QT = QTH + QTL + QTTR (D-8)
= 9.8 ± 14.5 mg/s at the
95% confidence level
54
-------
Table D-5. TIME-AVERAGED EMISSION RATES
Activity
Machine
activity
Loading
Transport
Time of activity . Emission ^?}?^e?
Composite time
hr
(T \
H\ 0.59
TTJ 0.69
/ T \
/ LL \ 0.10
\TT// 0.69
(T \
TR\ 0.035
TT j 0.69
rate
mg/s
(QH) 8.38
(QL) 1.76
(QTR) 47.0
cm-La a _L<_iii
rate
mg/s
(QTH) 7.16
(QTL) 0.26
(QTTR) 2.38
Free silica was detected by sampling the harvest machine
activity. For a sample of 0.6 mg collected, 0.014 mg of
free silica (detected as quartz) was present. This consti-
tutes 2.3% (by weight) of the particulate from the machine
activity. The grain harvested contained 0.012% silicon44
whereas the soil contained 62.1% silica in the upper 38 mm.45
Assuming these figures reflect the proportion of free silica
in the dust, it is concluded that the free silica originates
from the soil.
4ltKent, N. L. Technology of Cereals with Special Reference
to Wheat. The Commonwealth and International Library of
Science, Technology, Engineering, and Liberal Studies
Research Association of British Flour Millers, 1966. 262 p,
45Soil Classification - a Comprehensive System - 7th Approxi-
mation. U.S. Department of Agriculture, Soil Survey Staff,
Soil Conservation Service.
Washington. August 1960.
U.S. Government Printing Office.
265 p.
55
-------
Free silica contents of soils where grains are harvested
have a maximum respirable free silica content somewhere
between 5% and 10%.46 The free silica content of a soil is
basically equal to the free silica content in the dust.47
Emissions of free silica, Qc, are therefore generated by the
o
machine activity and transport on the field. The weighted
emission rate for these two operations is 9.54 ± 7.03 mg/s
at the 95% confidence level.
2. EMISSION FACTORS
The emission factor for the machine activity, E , is obtained
from the emission rate and the time required to harvest
0.043 km2. This is calculated in Equation D-9 as:
E = /8.38 mg\/ g W 0.59 hr \/3,600 s\ , q.
M \ s A 1,000 mg/V0.043 km2/\ hr / ( '
= 413.91 ± 834.8 g/km2
The emission factor for loading the harvested crop, ET, is
LI
the product of the emission rate and the time it takes to load
the truck divided by 0.043 km2, as shown in Equation D-10:
_ /1.76 mgw g w 360 s \ (n-
EL ~ I i Al,000 mgAO.043 km2J (D
= 14.71 ± 0.75 g/km2
For transporting the grain crop, the emission factor, ETR,
is the emission rate multiplied by the time of transport
tf6Personal communication. Dr. Warren Lynn and Dr. Steven
Holzhey. National Soil Survey Laboratory, Lincoln, Nebraska.
September 4, 1975.
[*7Sheinbaum, M. Comparative Concentration of Silica in Parent
Material and in Airborne Particulate Matter. American Indus-
trial Hygiene Association Journal. 22^(4) :313-317, August 1961.
56
-------
associated with the harvesting of 0.043 km2 divided by the
harvest area. This is calculated in Equation D-ll:
- /47 mgW g w 126 s
~ \ s / \1,000 mgAo.043 km2
= 137.7 ±76.2 g/km2
The composite emission factor, E , for the harvesting of grain
is the summation of the emission factors for each of the grain
activities. This factor is calculated in Equation D-12:
ET = EH + EL + ETR {D-12)
= 413.9 + 14.7 + 137.7
= 566.3 ± 838.3 g/km2
In Equation D-13, the emission factor for free silica, Ec, is
o
computed from the emission factors for machine activity and
transport of the harvest of 0.043 km2.
= 551.6 ± 838.3 g/km2
The variation of these emission factors represents the devia-
tion at the source sampled; however, these variations do not
apply to all sources. Confidence limits are not used since
this was a preliminary sampling of one source, two grain
types.
57
-------
APPENDIX E
DERIVATION OF THE REPRESENTATIVE SOURCE
The individual emission sources from the harvesting of grain
are the fields and farms upon which these activities occur.
A representative source is the arithmetic mean size of a
grain field harvested per farm. There are 380,596 farms
harvesting grain in the United States.10 Table E-l11 lists
the number of farms harvesting each crop. Dividing the total
from Table E-l (850,347) by the total number of grain farms
(380,596) yields the arithmetic mean number of grain crops
harvested per farm, 2.23. The size of each grain field is
taken as the arithmetic mean of the average size of each
grain farm per state (Table E-2).10/11 This field is
0.44 km2 ± 0.06 km2 at the 95% confidence level. The average
grain farm harvests (2.33)(0.44) or 0.98 km2 of land.
However, the crops are seasonal, harvested at different
periods during the year. The release of particulates or
maximum concentration thus occurs only when a single crop is
harvested, and the representative source occurs when the
arithmetic mean grain field area of 0.44 km2 is harvested.
It takes (13.62 hr/km2)(0.44 km2) or 6.0 hr to harvest this
crop. Assuming the field is square, 660 m x 660 m, the
average transport distance (and therein distance to the.
boundary) is 1/2(660 m), or 330 ± 122 m at the 95% confidence
level. The state population densities are listed in
58
-------
Table E-l. NUMBER OF FARMS HARVESTING EACH GRAIN11
Crop
Corn
Sorghum
Wheat
Oats
Barley
Rye
Soybeans
Flaxseed
TOTAL
Number of farms
220,465
51,156
205,562
102,573
43,015
10,291
205,641
11,644
850,347
Table E-2. AVERAGE SIZE OF EACH GRAIN FARM PER STATE10/11
State
Alabama
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Farm size,
km2
0.34
0.72
0.39
0.87
0.71
0.38
0.29
0.55
0.41
0.52
0.23
0.26
0.22
0.43
0.29
0.54
0.66
0.24
59
-------
Table E-2 (continued). AVERAGE SIZE OF EACH
GRAIN FARM PER STATE
State
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Farm size,
km2
N.A.
0.15
0.36
0.49
0.32
0.91
0.36
0.65
0.27
0.65
0.19
0.25
0.53
0.18
0.53
0.70
0.17
N.A.
0.34
0.53
0.29
0.55
0.47
N.A.
0.24
1.09
0.22
0.22
0.57
N.A. = not available.
60
-------
Table E-3.1*8 The arithmetic mean population density of all
the states (Table E-3) is 39.9 persons/km2.
The respirable free silica content of soil ranges from 0 to
10%. Soil upon which wheat harvesting is performed has a
high silt content (maximum 10%).
1*6
Therefore, sampling of
this soil illustrated that the free silica found in the dust
(2.33%) was within the same order of magnitude as the free
silica content of the soil.
Table E-3. POPULATION DENSITY PER GRAIN
HARVESTING STATE (persons/km2)47
State
Alabama
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Population density
27
7
15
50
9
240
106
48
31
4
76
57
20
11
31
30
12
Statistical Abstracts of the United States, 1973. U.S.
Department of Commerce, Social and Economic Statistics
Administration, Bureau of the Census. U.S. Government
Printing Office. Washington. Stock No. 0324-00113/
0324-00108. 1014 p.
61
-------
Table E-3 (continued). POPULATION DENSITY PER GRAIN
HARVESTING STATE (persons/km2)
State
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Population density
177
_a
60
18
18
27
2
7
2
32
3
145
39
2
102
15
9
103
34
2
38
17
5
-
46
20
27
31
1
Dashes indicate not applicable.
62
-------
APPENDIX F
CALCULATION OF SOURCE SEVERITY
Mean severity is calculated for each of the three operations:
harvest machine activity/ loading, and transport. For
criteria pollutants, severity is defined as the time-averaged
maximum ground level concentration (x^ , Equation G-2,
ITlciX
Appendix G) divided by the national primary ambient air quality
standard. Noncriteria pollutants are divided by an exposure
time-corrected TLV.
For average U.S. conditions (Class C stability, wind speed
4.5 m/s) the severity for respirable particulates is:
s =
p
where S = particulate (<7 ym) severity
"x = time average of maximum ground level partic-
max' ulate concentration, g/m3
F = national primary standard for total suspended
particulates, 2.6 x 10~4 g/m3
The representative distance is the same as the average field
transport distance of 330 m for the representative source
(see Appendix E) of 0.44 km2.
63
-------
For the harvest machine activity the point source model
(Equation C-2, Appendix C) is applied to Equation F-l to
yield a mean source severity of 11.2 x 10-t+. Loading of the
harvested grain crop has a severity of 3 x 10"5. Transport
of the crop while on the field has a severity of 0.017. With
all these activities occurring, the total severity is
3.5 x 10"3.
For noncriteria pollutants, the severity is calculated by
Equation F-2:
S = -^ (F-2)
where S = severity
F = corrected TLV (i.e., TLV • 8/24 • 1/100), g/m3
X = time-averaged maximum ground level
x concentration, g/m3
TLV = threshold limit value for the pollutant, g/m3
The TLV for particulates (containing >1% free silica) is
based on the maximum free silia content of soils, 10%. The
TLV is calculated13 as 10 mg/m3 (% quartz -t- 2) where % quartz
represents the free silica detected as quartz. The TLV is
thus calculated to be 0.83 mg/m3 and the hazard factor
F = 0.0028 mg/m3. Using Equation 1, the mean source severity
for free silica particles is <_ 0.29.
The affected population for respirable particulate severities
greater than 0.1 is zero persons since the severity is 0.0035
at the representative source. Free silica, however, has a
source severity of <^ 0.29. A severity of 0.1 is achieved
when in Equation F-3:
0.1 = (F_3)
64
-------
The value of F is 0.0028 mg/m3, or in Equation F-2,
0.00028 mg/m3 = x^,,- Solving Equation C-2, the value of
lUclX
x for severity S = 0.1 occurs at 576 m. Assuming a circu-
lar source, the area of the circle at 576-m radius (S = 0.1)
minus the area of the circle at 330-m radius (the plant
boundary severity level) will yield the area affected; hence:
Area affected = Tr(5762 - 3302) (F-4)
= 699,830m2
=0.7 km2
As the representative population density of 39.9 persons/km2,
the affected population for free silica is:
/39.9 persons \ ,_ _ , ?x no
\ - km? - / (° km2) = 28 persons
The source severity distribution for respirable particulates
is not developed since the severity for the representative
source is three orders of magnitude less than 1. However,
the free silica severity distribution is derived from
Equation F-2.
The value of x f°r free silica emissions is computed from
max
Equation C-2, Appendix C. Using C-2 in Equation F-2 results
in :
Q/TTO O U
S = - FY Z (F-5)
8 1
where F = TLV x 7JJ x -^Q 9/m3
At Class C stability and U.S. average wind speed (Appendix C) ,
Equation F-5 yields:
c _ 316Q ,_x
S -
65
-------
The value of TLV for free silica from grain harvesting is
0.83 mg/m3. Therefore Equation F-6 yields:
q -
5 ~
x1 •
Assuming grain production (P ) is proportional to the area of
the field:
(F-8)
where x equals distance to the plant boundary and K is a
constant.
Therefore, distance x is:
1/2
x = K2 (PQ) (F-9)
In Equation F-7, emission rate (Q) equals the production,
P.,, multiplied by an emission factor, E. Substituting
Q = PG • E and Equation F-9 into Equation F-6 yields:
380P • E
S = XI?BII» (P-10)
Severity for the representative plant, S , and production
rate, P , is thus:
380?^ • E
S = * (F-ll)
R xl • ° 1 ^
Dividing Equation F-10 by F-ll yields:
/p \0.093
S = S (|-) (F-12)
R VPR/
66
-------
Therefore the distribution of grain production
per farm
with the known representative production rate (P_.) and
R
severity (S^) will yield severities (S) for other sources.
r\
The distribution of harvested grain land is listed in Table
F-l. I"
Table F-l. DISTRIBUTION OF
HARVESTED GRAIN LAND10
Average farm
size, acres
803
409
259
146
83
Percent
9
19.4
25.9
24.3
21.4
The severity distribution, computed using Equation F-ll and
Table F-l, at
A\
presented in Table F-2.
= 0.29 and P^, = 0.98 km2 = 242 acres, is
r\
Table F-2. FREE SILICA SEVERITY DISTRIBUTION
Severity
0.32
0.30
0.29
0.28
0.26
Percent
9
19.4
25.9
24.3
21.4
Cumulative distribution is plotted in the text in Figure 2.
67
-------
APPENDIX G
DETERMINATION OF MAXIMUM POLLUTANT CONCENTRATIONS
The four categories of pollutants emitted from this source
are: (1) respirable particulates (less than 7~ym geometric
mean diameter) which are termed "inert" and nuisance,"
(2) respirable particles that contain free silica (detected
as quartz), (3) particulates which contain pesticide residue,
and (4) microorganisms on the particulates or detached from
them. These pollutants will be analyzed for comparison with
the evaluation criteria.
The downwind concentration of these pollutants is calculated
from Equation G-l:2 3
xmax ~ TTCT a u
y z
where x = the maximum concentration at a downwind
max distance (x), g/m3
Q = emission rate, g/s
u = average wind speed, m/s
a , 0 = dispersion standard deviations in horizontal
y z and vertical planes respectively
A "maximized" concentration is computed from the upper confi-
dence limit of the weighted emission rate and lower confi-
dence limits of the dispersion standard deviations. This
concentration is then compared to the hazard potential of
each emission. However, this concentration must be corrected
68
-------
for time-averaged wind direction variations not reflected in
a . The 24-hr concentration is thus calculated from
Equation G-2:
Xo = XK ^ (G-2)
S K \ts/
where x0 = tne concentration for sampling time, t0
o o
' = the concentration for the
is.
P = 0.17 to 0.20 (mean 0.185)
v = the concentration for the sampling time, t_
i\ j
The sampling time, tv, for concentrations obtained from
j\
Equation G-l is equivalent to the operation time of the
harvesting activity. For all pollutants considered, the
average U.S. wind speed is 4.5 m/s and the stability class
approximates C. The dispersion standard deviations (under
C stability) are calculated from Equations G-3 and G-4:
a = 0.2089(x°-9031) (G-3)
a = 0.113(x°-911) (G-4)
where x = downwind distance, m
The average grain field is harvested with a distance to the
boundary of 330 ± 122 m at the 95% confidence level. There-
fore, using Equations G-3 and G-4. the values of a and az
at the lower confidence level are 25.9 m and 14.6 m,
respectively.
The inert (nuisance) respirable particulates are emitted at
a weighted rate of 9.8 ± 7.4 mg/s (@ 95% confidence level)
from all grain harvesting operations (machine activity,
loading, and transport). Using Equation G-l, the maximum
concentration is corrected to a 24-hr exposure, using
69
-------
Equation G-2, to 1.17 yg/m3. The primary air quality stand-
ard for these particulates is 260 yg/m3. This is two orders
of magnitude greater than the maximum concentration obtained
when all grain harvesting operations are considered.
Particulates containing free silica are emitted at a weighted
rate of 9.54 ± 7.03 mg/s (at 95% confidence level) from the
harvest machine activity and the transport on field roads.
Using Equations G-l and G-2, the maximum concentration is
1.13 ug/m3. The threshold limit value for particulates
containing 10% free silica is 0.83 mg/m3 (Appendix F). This
TLV is corrected to the hazard factor, F, through Equation
G-5:
F = (TLV) (8/24) (1/100) (G-5)
Therefore, F = 2.76 yg/m3. This is over twice the maximum
concentration obtained when the machine activity and trans-
port of the crop occur simultaneously.
In Appendix A, pesticide residue concentration levels found
on plants were increased by three orders of magnitude to a
dust concentration level. For the pesticide with the lowest
TLV (Endrin), the hazard factor using Equation G-5 is
0.33 yg/m3. The maximum downwind concentration (Equations
G-l and G-2) is 7.9 x 10"3 yg/m3. This is two orders of
magnitude less than the hazard factor. For the pesticide
with the highest concentration (polychlorinated biphenyls),
the hazard factor is 1.66 yg/m3. The maximum concentration
level is 0.035 yg/m3. The hazard factor is two orders of
magnitude greater than this concentration.
The ranges of source severity are determined from the confi-
dence limits at the 95% level. For criteria pollutants (res-
pirable particulates) the emission rate is 9.8 ± 7.4 mg/s
70
-------
at a distance of 330 ± 122 m at the 95% level. The source
severity therfore ranges from 1.7 x 10~3 to 1.2 x 10~2. For
noncriteria pollutants the emission rate is 9.54 ± 7.03 mg/s
at a distance of 330 ± 122 m (at the 95% level) . The source
severity thus ranges between 0.17 and 1.12 (with the TLV
constant at 0.83 mg/m3 based on maximum respirable free silica
soil content) .
The population affected for free silica at severity of 0.1 to
the maximum 1.12 is calculated from the differences in down-
wind distance, x. As computed in Appendix F, S = 0.1 at
576 m, as S = 1.12,
1.12 = - (G-6)
and using Equation G-l, the value of x is 155 m. The area
affected is thus:
Area affected = ir(5762 - 1552) (G-7)
= 966,338 m2
=0.97 km2
The maximum population affected is thus:
(0.97 km2) 39'9er50nS = 39 persons
The maximum national and state emissions burdens, calculated
from the upper limit (@ 95% level) of emission factor, are
0.014% and 0.206%, respectively.
The data in this appendix are maximized values calculated
from confidence limits. These data are summarized and tabu-
lated in Table G-l. From inspection, the maximum severity
for free silica particulates (1.12) exceeds the evaluation
criteria. This value is calculated from the upper confidence
71
-------
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72
-------
limit of emission rate, and the maximum possible respirable
free silica soil percentage. However, this affects only 39
persons, not accounting for the fact that this is based on
state population densities. Farm fields are located in rural
areas where population densities are lower than state
population densities. In addition, the harvesting of the
representative field is accompoished in 6 hr as shown below:
13.62 hr /n * * -i 9\ f i-
(0.44 km2) = 6 hr
The corrected threshold limit values are based on a 24 -hr
annual exposure for a 5-day work week. Using the logic
applied in calculating the corrected TLV, the TLV for dose
exposure to free silica could be corrected by the multiplier:
/24 hr\/260 day\
\ day /\ yr /
= 9.6 x
Given the above levels, coupled with the fact that grain
harvesting is a basic and highly necessary function of the
economy, further consideration of the source via sampling was
not deemed necessary.
73
-------
SECTION IX
GLOSSARY
ANEMOMETER - A rotating cup device used at a meteorological
station for measuring wind speed.
ATMOSPHERIC STABILITY CLASS - A categorization used to
describe the turbulent structure and wind speed of the
atmosphere.
ATTRACTANTS - Chemicals used to lure pests away from
cultivated crops.
BALER - A mechanical device used to tie the grain crop into
bundles.
BETA ABSORPTION - The degree of attenuation of beta rays
passing through a medium.
BINDER - A machine that cuts and binds a crop into bundles.
CHAFF - Plant tissue fragments from threshed grain.
COMBINE - A machine that cuts, screens, and threshes grain
in one operation.
CONFIDENCE LEVEL - The probability that a random variable
lies within a given range with a normal distribution.
CONFIDENCE LIMITS - The upper and lower boundaries of a range
in which a random variable can exist at a given probability.
CONTOURING - Creating furrows along natural elevation lines
so as to avoid erosion.
CRITERIA POLLUTANTS - Particulate matter, carbon monoxide
sulfur dioxide, and hydrocarbons.
EMISSIONS BURDEN - The ratio of a pollutant from a source
category to the state and national level of that pollutant.
74
-------
ENTRAINMENT RATE - The rate of wind capture of dust particles,
FORAGE - Vegetable matter, fresh or preserved, utilized as
feed for animals.
FREE SILICA - Silicon dioxide molecules oriented in a fixed
pattern.
GRANULOMATOUS - Containing chronically inflamed tissue marked
by the formation of granulations.
INFLORESCENCE - The flowering portion of the plant.
INSOLATION CLASS - Factor expressing the radiation received
by the earth's surface.
NONCRITERIA POLLUTANT - Any pollutant for which ambient air
quality standards have not been established.
PICKER/PICKER-SHELLER - Machines that mechanically pick and
husk the cobs from the corn plant. The sheller unit also
removes the kernels.
PULMONARY FIBROSIS - An abnormal increase in the amount of
fibrous connective tissue in the lungs.
QUARTZ - SiO2; a brilliant, crystalline mineral.
RADIATION INDEX - Relative categorization used to describe
incoming solar waves.
SEVERITY - The ratio of the maximum concentration of a
pollutant to the hazard factor of that pollutant.
SHELTERBELT - A row of trees or bushes planted perpendicular
to the prevailing wind direction to shield a field from wind
erosion.
SHOCK - A group of grain sheaves stacked together.
SILAGE - Forage that has been stored and preserved in a
succulent condition by partial fermentation.
SILICOSIS - A chronic disease of the lungs caused by the
continued inhalation of silica dust.
SMUT - Plant disease characterized by the appearance of
masses of spores which break up into a find powder.
SPECTROPHOTOMETRY - The analytical technique for comparing
the color intensities of different spectra.
75
-------
STRIPCROPPING - Crop planting in which strips of heavy rooted
and loose rooted plants are alternated to lessen wind erosion.
SWATH - A strip of cut herbage lying on the stubble.
TERRACES - Flat platforms of earth with sloping sides, rising
one above the other to lessen wind erosion.
WEATHERING - The partial digestion of the starch and increase
of mold growth on the grain kernel.
WINDROW - A row of grain plants raked together to dry before
being baled or put into shocks.
76
-------
SECTION X
CONVERSION FACTORS AND METRIC PREFIXES49
CONVERSION FACTORS
To convert from
2 o
grams/kilometer (g/km )
grams/meter (g/m )
grams/sec (g/sec)
kilogram (kg)
kilogram (kg)
kilogram (kg)
kilometer/hour (km/hr)
q o
kilogram/meter (kg/m )
kilometer2 (km2)
meter (m)
meter (m)
meter (m)
meter/second (m/sec)
f\ o
meter (m )
meter (m )
meter3 (m3)
meter3 (m3)
meter3/kilometer2 (m3/km2)
metric ton
micrograms/meter (yg/m3)
milligrams/kilogram (mg/kg)
to
pounds/acre
pounds/bushel
grains/sec
grains
pound (mass)
ton
miles/hr
pounds/ft3
acres
feet
mil
mile
feet/sec
acres
Multiply by
9
7
1
1
2
1
6
6
2
3
3
6
3
2
.124
.770
.543
.543
.205
.102
.215
.242
.471
.281
.937
.215
.281
.471
x
x
X
X
X
X
X
X
X
X
X
10
10
10
10
10
10
10
10
10
10
10
-6
-5
1
4
-3
-1
-1
2
4
~k
-k
bushels (U.S.)
feet3
bushels/acre
pound (mass)
q
grains/yard
grains/ton
^Metric Practice Guide. American Society for
Materials. Philadelphia, ASTM Designation:
November 1974. 34 p.
1.076 x 101
2.838 x 101
3.531 x 101
1.150 x 10-1
2.205 x 103
1.180 x 10~5
1.400 x 101
Testing and
E380-74,
77
-------
CONVERSION FACTORS (continued)
To convert from to Multiply by
milligrams/second (mg/s) grains/sec 1.543
milligrams/meter3 (mg/m3) grains/feet3 4.371 x 10"
persons/kilometer2 (persons/km2) persons/acre 4.047
PREFIXES
Multiplication
Prefix Symbol factor Example
kilo k 103 1 kg = 1 x 103 g;
1 km2 = (103 m)2 = 106 m2
milli m 10~3 1 mg = 1 x 1CT3 g
micro y 10~6 1 ym = 1 x 1C"6 m
78
-------
SECTION XI
REFERENCES
1. The Official United States Standards for Grain. U.S.
Department of Agriculture, Agricultural Marketing
Service, Grain Division. U.S. Government Printing
Office. Washington. Stock No. 0116-00094. June 2,
1974. 66 p.
2. Private communication. Mr. H. B. Drake. Montgomery
County Agricultural Extension Agency (Ohio). July 8,
1975.
3. Wilson, H. K. Grain Crops, 2nd Edition. New York,
McGraw-Hill Book Co., 1955. 396 p.
4. Kipps, M. S. Production of Field Crops, 6th Edition.
New York, McGraw-Hill Book Co., 1970. 790 p.
5. Encyclopaedia Brittanica, 1974 Edition. Volume 1 -
Technology of Agriculture. Chicago, Encyclopaedia
Brittanica, Inc., 1974. p. 357-361.
6. Spear, R. C., and W. J. Popendorf. Preliminary Survey
of Factors Affecting the Exposure of Harvesters to
Pesticide Residues. American Industrial Hygiene
Journal. 3^5:374-380, June 1974.
7. Harris, L. H. Allergy to Grain Dusts and Smuts.
Journal of Allergy and Clinical Immunology.
10^:327-336, 1939.
8. Dickson, J. G. Diseases of Field Crops, 2nd Edition.
New York, McGraw-Hill Book Co., 1956.
9. Hirst, J. M. Chapter 47 - Spore Liberation and Disper-
sal. In: Plant Pathology - Problems and Progress,
1908-1958, Hotton, C. S. et al.(ed.). Madison, The
University of Wisconsin Press, 1959. p. 529-538.
79
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10. 1969 Census of Agriculture; Volume II, General Reports;
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83
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-77-107f
3. RECIPIENT'S ACCESSION-NO.
*• TITLE AND SUBTITLE SOURCE ASSESSMENT: HARVESTING
OF GRAIN, State of the Art
5. REPORT DATE
July I
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
R.A. Wachter and T.R. Blackwood
8. PERFORMING ORGANIZATION REPORT NO.
MRC-DA-698
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
10. PROGRAM ELEMENT NO.
1AB015; ROAP 21AXM-071
11. CONTRACT/GRANT NO.
68-02-1874
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND.PERIOD COVERED
Task Final; 5-12/75
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTES
IERL-RTP task officer for this report is David K. Oestreich,
Mail Drop 62, 919/541-2547.
is. ABSTRACT The repOrt describes a study of air pollutants generated by the harvesting
of grain. Grain harvesting produces respirable particulates in the form of soil dust
and plant tissue fragments. The former contains free silica, while the latter contains
pesticide residues and microorganisms. Emissions are generated by the harvest
machine activity, loading of the harvested crop, and transport while on the field. The
source severity was 0.0012 for respirable particulates and < or =0.11 for free silica.
Grain harvesting contributes 0.006% of the national particulate emissions burden.
(Source severity is a measure of the hazard potential of a representative emission
source; for this source type, it was defined as the ratio of the time-averaged maxi-
mum ground level concentration of a species emitted, to a hazard factor which is the
primary AAQS for ^articulate and a time-adjusted TLV for silica.) Specific air
pollution control technology for grain harvesting is presently nonexistent.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution
Grain Crops
Harvesting
Agricultural Machinery
Dust
Soils
Plant Tissues
Silicon Dioxide
Pesticides
Microorganis ms
Air Pollution Control
Particulates
Source Severity
13 B
02 D
02C
11G
08G,08M
06C
07B
06F
06M
IS. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
96
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
84
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