United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/3-81-006
May 1981
Air
Assessment and Control
of Chrysotile Asbestos
Emissions from
Unpaved Roads
-------
EPA-450/3-81-006
Assessment and Control of
Chrysotile Asbestos Emissions
from Unpaved Roads
Emission Standards and Engineering Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air, Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
May 1981
-------
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the contents necessarily
reflect the views and policy of the Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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TABLE OF CONTENTS
Section
Title
Page
List of Tables .
List of Figures .......
CHAPTER 1
CHAPTER 2
2.1
2.2
2.3
2.4
2.5
2.6
2.7
CHAPTER 3
3.1
3.2
3.3
3.4
3.5
CHAPTER 4
4.1
4.2
SUMMARY
ASBESTOS MINERALOGY, REGULATIONS, MEASUREMENT,
TECHNIQUES, ENVIRONMENTAL CONTAMINATION, FIBER
AERODYNAMICS, AND HUMAN HEALTH EFFECTS
Asbestos Mineralogy
OSHA, MSHA, and EPA Asbestos Regulations
Asbestos Measurement Techniques
Environmental Contamination
Asbestos Fiber Aerodynamics
Human Health Effects Associated With Inhalation of
Asbestos
References for Chapter 2
EXPOSURE ASSESSMENT FOR CRUSHED STONE CONTAINING
CHRYSOTILE
Detection of Asbestos Emissions in Maryland in 1976 .
Nationwide Investigation of Chrysotile Emissions From
Roadways and Quarries
Asbestos Sampling, 1979
EPA Response to Advance Notice of Proposed Rulemaking
(42 FR 58543)
References for Chapter 3
EMISSION CONTROL ALTERNATIVES AND ADMINISTRATIVE
OPTIONS
Introduction
Emission Control Alternatives
iv
vi
1-1
2-1
2-1
2-2
2-5
2-6
2-7
2-9
2-16
3-1
3-1
3-2
3-7
3-10
3-12
4-1
4-1
4-1
-------
TABLE OF CONTENTS
Section Title
4.3 Administrative Options 4-15
4.4 References for Chapter 4 4-17
CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS 5-1
5.1 Conclusions 5-1
5.2 Recommendations 5-1
APPENDIX A FEDERAL ASBESTOS REGULATIONS A-l
APPENDIX B SAMPLING AND ANALYSIS OF AIRBORNE CHRYSOTILE ASBESTOS
CONCENTRATIONS AT FIVE TEST SITES B-l
B.I Test Program Description B-l
B.2 Sample Filter Handling B-3
B.3 Sample Analysis B-5
B.4 Site-Specific Tests: Description and Results .... B-7
B.5 Laboratory Comparisons B-l9
B.6 Quality Assurance B-19
B.7 Conclusions B-19
m
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LIST OF TABLES
Table
Table 2-1
Table 3-1
Table 3-2
Table 3-3
Table 3-4
Table 4-1
Table 4-2
Table 4-3
Table 4-4
Table A-l
Table A-2
Table A-3
Table A-4
Table A- 5
Table B-l
Tables
B-2
through
B-8
Title
Physical, Chemical, and Mineralogical Properties of
Varieties of Asbestos .
States Where Deposits of Serpentinite Rock Occur . . .
Quarries Producing Crushed Serpentinite Containing
Chrysotile Confirmed Through Petrographic and/or EM
Analysis of Stone Product
Unpaved Roads Surfaced With Quarried Serpentinite and
the Estimated Number of Nearby Residents
Serpentinite Quarries and Unpaved Roads Located on
Federal Lands
A Comparison of Control Alternatives for Reducing
Chrysotile Emissions From Unpaved Roads
Dust Suppressant Manufacturers
Performance Ratings and Road Conditions for Selected
Road Stabilizers Mixed into Soil
Performance Ratings and Road Conditions for Selected
Road Dust Suppressants, Spray-On Application
Occupational Safety and Health Administration Asbestos
Regulations
Mine Safety and Health Administration Asbestos
Regulations
Environmental Protection Agency Asbestos Regulations .
Consumer Product Safety Commission Asbestos
Regulations
Food and Drug Administration Asbestos Regulations . . .
Analysis of Eight Crushed Stone Samples for Chrysotile
Fiber and Mass Content Performed by the University of
Minnesota at Duluth
Sampling and Analysis of Chrysotile Asbestos Emissions
From Holy Cross Road
Page
2-3
3-4
3-5
3-6
3-8
4-2
4-7
4-13
4-14
A-2
A-4
A- 5
A-8
A-9
B-21
B-22
through
B-28
IV
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LIST OF TABLES
(concluded)
Table Title Page
Tables Sampling and Analysis of Chrysotile Asbestos Emissions B-29
B-9 From McNabb Road through
through B-35
B-15
Table B-16 Sampling and Analysis of Ambient Chrysotile Asbestos
Concentrations in the Clear Creek Federal Recreational
Area, San Benito County, California B-36
Table B-17 Sampling and Analysis of Chrysotile Asbestos Emissions
Near a Serpentinite Quarry in the Eastern United
States B-37
Table B-18 Sampling and Analysis of Chrysotile Asbestos Emissions
Near a Serpentinite Quarry in the Western United
States B-38
Table B-19 Statistical Evaluation of Chrysotile Fiber
Concentrations Reported by Two Laboratories Analyzing
Split and Colocated Samples B-39
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LIST OF FIGURES
Figure Title
Figure 2-1 Distribution of Ultramafic and Metamorphic Rock
Formations in the United States 2-4
Figure 2-2 Comparison of Asbestos Fibers and Other Particles By Size
and Measurement Techniques ..... 2-8
Figure B-l Site 1—Holy Cross Road, Harford County, Maryland . . B-8
Figure B-2 Chrysotile Fiber Concentrations (Geometric Average)
Versus Downwind Receptor Distance for Seven Sampling
Runs at Holy Cross Road B-10
Figure B-3 Total Suspended Particulate Concentrations for Two
Days of Sampling at Holy Cross Road B-12
Figure B-4 Average (Geometric) Chrysotile Fiber Concentrations
Versus TSP Concentrations for Two Sets of Runs with
2 Different Chrysotile (By Weight) Concentrations
in the Roadstone B-13
Figure B-5 Site 2: McNabb Road, Harford County, Maryland .... B-14
Figure B-6 Upwind and Downwind Chrysotile Fiber Concentrations
(Geometric Average) for Seven Sampling Runs at McNabb
Road B-16
VI
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1. SUMMARY
Asbestos is a commercial term for the following group of naturally
occurring fibrous minerals: chrysotile, crocidolite, cummingtonite-
grunerite asbestos, anthophyllite asbestos, tremolite asbestos, and
actinolite asbestos. The most widely used form of asbestos is chrysotile,
which is found in serpentinite rock deposits. Asbestos fibers are released
to the atmosphere primarily through human activity and to a lesser degree
by natural forces in areas where outcroppings of asbestos-containing rock
occur.
Inhalation of asbestos fibers has been associated in humans with
asbestosis (diffuse interstitial fibrosis of the lung), respiratory
cancer, and mesothelioma (a rare cancer of the pleural and abdominal
lining). Researchers have been unable to determine quantitatively if
there is a safe level of exposure below which asbestos-induced cancer
will not occur. Several studies have shown qualitatively that the risk
of asbestos-induced disease increases as the duration and/or intensity of
asbestos exposure increases. Currently, there is a lack of agreement in
the medical community concerning the relative fibrogenicity and carcino-
genicity of short (less than 5 micrometers [|jm] in length) versus long
(greater than 5 (jm in length) fibers. Consequently, the Environmental
Protection Agency (EPA) believes that human exposure to all airborne
asbestos fibers should be reduced to the greatest extent practical.
In 1977 airborne asbestos mass concentrations about 1,000 times
greater than those typically found in urban air were found near unpaved
roads surfaced with crushed serpentinite rock in Montgomery County,
Maryland. EPA tests indicated that the crushed stone (supplied by a
local quarry) contained from 0.1 to 0.7 percent chrysotile by weight.
Analysis of airborne particulate samples collected downwind of unpaved
1-1
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roads surfaced with crushed serpentinite showed that vehicular traffic
over these roads caused increased asbestos concentrations in the atmosphere.
EPA recommended that the State of Maryland and Montgomery County act to
control such emissions. Montgomery County responded by paving all unpaved
roads surfaced with serpentinite (92 miles of roads) and by removing or
covering all such stone in playgrounds or parks.
The Montgomery County Department of Environmental Protection (DEP)
conducted additional monitoring studies in 1977-1978 to further assess
the uses of crushed serpentinite with respect to asbestos emissions.
From these studies, DEP concluded that:
. . . elevated asbestos levels occurred only on untreated,
unpaved road surfaces or on bare stone surfaces with
moderate-to-heavy vehicular traffic creating dusty
conditions .... Using crushed serpentinite on driveways,
road shoulders, parking lots, biking paths and other areas
of relatively low traffic does not seem to cause elevated
ambient asbestos levels .... Lightly traveled surfaces
should be surfaced with a dust suppressant.
The DEP did not define the terms "elevated asbestos levels" or "moderate-to-
heavy vehicular traffic."
Because of the probability that additional unpaved roads in other
areas of the country were surfaced with crushed serpentinite, EPA announced
that regulations would be proposed to limit the production and use of
crushed serpentinite if the Agency determined that the use of such stone
was causing asbestos emissions proximate to the public in a number of
locations (Federal Register, November 10, 1977). In order to determine
the need for a regulation, EPA undertook a study with the following
objectives: (1) to determine the extent to which quarrying operations
are being conducted in the United States in serpentinite rock deposits,
(2) to measure the chrysotile concentration of the rock being quarried,
(3) to locate areas where crushed serpentinite is used to maintain unpaved
public roads, (4) to determine if the use of crushed serpentinite for
road surfacing results in elevated airborne chrysotile concentrations,
(5) to estimate the number of individuals potentially exposed to asbestos
emissions from these roads, and (6) to recommend control alternatives.
A nationwide study of the quarry industry found only 12 private
quarries that produce crushed serpentinite. The chrysotile content of
1-2
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the stone from these quarries ranges from trace amounts to 2.7 percent by
weight. Crushed serpentinite from five of these quarries is used to
maintain about 400 miles of county roadways in California, Virginia,
North Carolina, and Maryland. An estimated 6,500 people reside within
approximately 200 feet of these roads. Serpentinite from the remaining
seven quarries is not used for surfacing unpaved public roads.
The U.S. Forest Service (USFS) has determined that approximately
30 quarries on Federal lands in California and Oregon produce crushed
serpentinite stone. Crushed stone from these quarries is primarily used
to maintain about 300 miles of intermittently used logging roads on
Federal forest lands. In the same general vicinities, approximately
1,000 miles of unpaved roads have been constructed over natural outcroppings
of serpentinite. A massive outcropping of serpentinite also occurs in
San Benito County, California, where a 43,000-acre Federal recreation
area is maintained by the Bureau of Land Management (BLM). The USFS and
BLM are further assessing the occurrence and use of serpentinite on
Federal land.
EPA conducted an extensive air sampling program in 1979 to assess
chrysotile fiber concentrations near several unpaved roads with serpentinite
surfaces and near two serpentinite quarries. Sampling was conducted at
the road sites to determine if there is a quantitative relationship
between the level of asbestos emissions and three major variables:
chrysotile content of the crushed stone, traffic characteristics, and
local meteorological conditions. A total of 153 airborne particulate
samples and 10 crushed rock samples from the various sampling sites were
analyzed for chrysotile by transmission electron microscopy (TEM). T-hese
analyses indicate that chrysotile concentrations downwind of unpaved
roads surfaced with crushed serpentinite (containing less than one percent
chrysotile) are significantly higher statistically than upwind concentra-
tions when light to moderate traffic occurs across the roadways.
Specifically, chrysotile fiber concentrations as high as 1.33 fibers/ml
were measured 61 meters downwind of an unpaved road when 20 vehicle
passes occurred during a 2-hour sampling period. The crushed road stone
was found to contain 0.14 percent chrysotile (by weight). Higher chrysotile
fiber concentrations were found closer to the roadways. Because of
1-3
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variations in the sampling data, no statistical relationship was determined
concerning the influence of downwind distance, chrysotile content of the
road stone, traffic conditions, or wind speed on chrysotile emissions.
Analysis of airborne particulate samples collected near two serpentinite
quarries indicates that serpentinite quarries are not a major source of
airborne asbestr-s to the surrounding area.
Small concentrations of amphibole fibers were found in some airborne
particulate and crushed stone samples. These concentrations are not
reported with the test results in Appendix B because the purpose of this
study was to assess chrysotile emissions from crushed serpentinite and
because not all the participating laboratories had the analytical capability
to positively identify amphibole fibers. It should also be noted that
chrysotile fiber concentrations reported in this document are not directly
comparable to asbestos concentrations found in occupational settings.
This study's chrysotile results were determined by electron microscopy.
Analysis of samples collected in the workplace is conducted using phase
contrast microscopy, which is not mineral-specific. In addition, nearly
all the chrysotile fibers detected in this study were shorter than 5 urn
in length and less than 1 urn in diameter and thus would not have been
detected by techniques other than electron microscopy.
EPA believes that asbestos emissions from unpaved roads and other
dusty sources (such as unpaved parking lots) should be reduced to the
greatest extent practical. Survey information and field studies found
that asbestos emissions from unpaved roads surfaced with crushed
serpentinite are limited to a few locations in the United States and may
affect a very small segment of the general population. The level of
asbestos emissions as well as the most appropriate method to control
those emissions varies with location. EPA has concluded that local,
State, and Federal agencies that maintain these roads are in the best
position to assess local conditions and implement the most appropriate
control measures.
EPA has developed this document to inform officials about asbestos
emissions within their jurisdictions and to provide those officials with
information concerning various methods to control asbestos emissions from
unpaved roads. Effective emission control techniques include paving,
1-4
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applying chemical dust suppressants, removing and/or replenishing crushed
roadstone, and controlling traffic. In addition, administrative and
regulatory options are available to State and local officials to ensure
that crushed serpentinite is not used for maintaining unpaved public
roads.
1-5
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2. ASBESTOS MINERALOGY, REGULATIONS, MEASUREMENT, ENVIRONMENTAL
CONTAMINATION, FIBER AERODYNAMICS, AND HUMAN HEALTH EFFECTS
2.1 ASBESTOS MINERALOGY
Asbestos is a commercial term for the following group of naturally
occurring fibrous minerals: chrysotile, crocidolite, cummingtonite-
grunerite asbestos, anthophyllite asbestos, tremolite asbestos, and
actinolite asbestos. The term "asbestos fiber" is used to define a
particle of any of the above-mentioned minerals having an overall length-to-
width ratio of 3:1 or greater and with substantially parallel sides. EPA
does not recognize the distinction made by other Federal agencies that such
a particle must also be at least 5 urn in length to be considered an asbestos
fiber.
Asbestos varieties belong to either the serpentine group or the
amphibole group of minerals. Chrysotile is the fibrous variety of the
serpentine group. Rock containing mainly serpentine minerals (serpentinite)
usually contains chrysotile asbestos. Chrysotile fibers are spirally wound,
hollow tubes with a curved morphology. The chemical bonding between
individual tubes is very weak, and fibers can separate into fibrils (smaller
fibers) as thin as the diameter of an individual tube. Individual fibrils
measure from 0.02 to 0.035 urn in diameter. Chrysotile accounts for more
than 90 percent of all asbestos used commercially.
The fibrous amphibole varieties--cummingtonite-grunerite asbestos,
anthophyllite asbestos, crocidolite, tremolite asbestos, and actinolite
asbestos—have straight and solid fibers generally larger in diameter than
chrysotile fibers. The fibrous amphiboles are found in metamorphic rock and
account for the remaining 10 percent of asbestos used commercially.
The unique physical, chemical, and mineralogical properties of asbestos
varieties that make the use of these fibers attractive to industry are shown
2-1
-------
in Table 2-1. The geologic areas of the United States where asbestos
generally is most likely to occur are shown in Figure 2-1.
2.2 OSHA, MSHA, AND EPA ASBESTOS REGULATIONS
The first standard in the United States that limited worker inhalation
of asbestos fibers was promulgated by the Occupational Safety and Health
Administration (OSHA) in 1971. The regulation was revised in 1972 and in
1976 (see Appendix A, Table A-l). The current standard limits worker
exposure (an 8-hour, time-weighted average) to a maximum of two fibers,
longer than 5 urn in length, per cubic centimeter of air. Exposure may
not exceed 10 fibers per cubic centimeter at any time, as determined by
the membrane filter technique at 400 to 450 magnification with phase
contrast illumination. The Mine Safety and Health Administration (MSHA)
has a similar standard except that the 10-fiber-per-cubic-centimeter
ceiling value may be exceeded for a total of 1 hour each 8-hour day (see
Appendix A, Table A-2).
The National Institute of Occupational Safety and Health (NIOSH)
acknowledges that OSHA's standard is designed to prevent asbestosis and
states that there is insufficient information to establish a standard to
prevent asbestos-related neoplasms other than a standard that limits
worker exposure to zero asbestos emissions.4 In April 1980 NIOSH recom-
mended lowering the exposure standard to 0.1 fiber/ml from the current
standard of 2 fibers/ml because the lower value represents the lowest
level that can be measured accurately by currently available optical
microscope techni ques.4
EPA listed asbestos as a hazardous air pollutant in 1971. The
Agency has followed a policy of limiting asbestos emissions to the greatest
extent practical through the use of procedural and visible emissions
standards. Subsequently, EPA has prohibited surfacing roads with asbestos
mine tailings, prohibited visible asbestos emissions from asbestos mills
and manufacturing facilities, established work practice standards for the
demolition of buildings containing asbestos, limited the asbestos content
of materials used to insulate or fireproof buildings and pipes, and given
guidance for assessing and removing asbestos-containing materials from
school buildings. (See Appendix A, Table A-3).
2-2
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TABLE 2-1. PHYSICAL, CHEMICAL, AND MINERALOGICAL PROPERTIES OF VARIETIES OF ASBESTOS1 2
CJ
Property
Mineral group
Chemical formula
Crystal system
Optical properties
Resistance to
destruction by heat
Hardness*
Flexibility
Spinnabllity
Tensile strength.
Resistance to acids
Color
Chrysolite
Serpentine
Hg,SI,Ofc(OH)4
Honoclinlc and
ortho rhombic
Biaxial positive.
extinction parallel
Good, brittle at
high temperatures
2.S-4.0
High
Very good
824.000 MX.
Poor
Green, gray.
amber to white
Croc idol lie
Amphibole
Na,Fe,Si.O,s(OH),
Nonoclinlc
Biaxial t.
extinction parallel
Poor, fuses
4
Good
Fair
876.000 MX.
Good
Blue
Cummingtonlte-
GrunerTte
asbestos
Amphibole
(Fe.Mg),SI.Oss(OH),
Nonoclinlc
Biaxial positive.
extinction parallel
Good, brittle at
high temperatures
5.5-6.0
Good
Fair
16.000-90.000
—
Cray, yellow to
dark brown
Anthophyllite
asbestos
Amphibole
(FeNg),SI.Oa2(OH),
Ortho rhombic
Biaxial positive.
extinction parallel
Very good
5.5-6 0
Poor
Poor
4.000 and lass
—
Yellowish brown.
grayish white
Tremotite
asbestos
Amphibole
Ca1(HgFe)i
Nonoclinic
Biaxial negative.
extinction parallel
Fair to good
5.5
Poor
Poor
1.000-8.000
Good
Gray-white.
greenish-yellowish,
bluish
Acttnolite
asbestos
Amphibole
(Ca2(MgFe)sSt.022(OH)2
Honoclinlc
Biaxial negative,
extinction parallel
--
61
High
Poor
1.000 and less
Good
Greenish
*Working scale of hardness: I—very easily scratched by fingernail and has greasy feel to the hand; 2--easlly scratched by fingernail; a—scratched by
brass pin or copper coin; 4—easily scratched by knife; 5--scratched with difficulty with knife; 6—easily scratched by file; 7— little touched by rile
but will scratch window glass. All harder than 7 will scratch window glass.
-------
NOTE:
Ultramafic rocks, mafic plutom'c rocks, and
similar basic intrusives. Ultramafic rock
is very low in silica and rich in iron and
magnesium minerals. Serpentinite is a type
of ultramafic rock.
Areas of extensive high-rank (severe) metamorphism
where amphiboles are most likely to be found.
Inferred ultrabasic intrusive rock where amphiboles
may be found.
In Hawaii, the type of mineral alteration that could lead to
formation is quite restricted (to the vicinity of the Koolau
and Molokai volcanoes on the island of Oahu).
Figure 2-1. Distribution of ultramafic and metamorphic
rock formations in the United States.3
2-4
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2.3 ASBESTOS MEASUREMENT TECHNIQUES
2.3.1 Air Sample Analyses
Airborne particles are initially collected on the surface of a
small-pore size filter through which a known volume of air is drawn.
Asbestos fiber concentrations are then estimated by either phase contrast
microscopy (a special application of the optical microscope) or by electron
microscopy (EM). In general, asbestos fiber concentration data obtained
by one of these two methods cannot be converted to a concentration
determined by the other method. In phase contrast microscopy, a section
of a membrane filter is viewed at 400 magnification, and all particles
which have at least a 3:1 length-to-width ratio and a length of 5 urn or
greater are counted as asbestos fibers. Fibers smaller than 0.1 urn in
diameter are not visible by phase contrast microscopy. Consequently,
identification of smaller size fibers which may be of biological signifi-
cance is precluded. Fiber counting by phase contrast microscopy is based
entirely on particle shape and is not specific for asbestos. This method
is the standard method for measuring asbestos in the workplace. In cases
where all fibers are smaller than 5 urn in length or thinner than 0.1 pm
in diameter, no detectable fiber count will result.
By comparison, electron microscopy permits positive identification
of asbestos fibers that are not observable by phase contrast microscopy.
Chrysotile fibers are relatively easy to distinguish from other types of
fibers because of their unique tubular structure. Selected area electron
diffraction (SAED) and energy dispersive X-ray diffraction (EDX) are
often used to substantiate fiber identification. In EM analysis, only a
very small fraction of the filter is viewed at a magnification of 15,000
to 20,000 X.
When determining asbestos concentrations in airborne particulate
samples by either phase contrast microscopy or EM, visible fiber counts
are used to estimate the total fiber count for the whole filter. The
accuracy of the calculated fiber concentration is primarily dependent
upon the representativeness of the fiber population actually counted.
The method of sample preparation and fiber counting strongly influence
the results obtained by EM. EPA developed a provisional methodology in
2-5
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1977 that optimized various techniques for analyzing and counting airborne
asbestos fibers by EM. Testing of the provisional methodology showed inter-
laboratory variation in fiber concentration results to be about20 percent
for samples collected in an industrial setting and samples prepared in the
laboratory.5 6
2.3.2 Bulk (Rock) Sample Analysis
Petrographic microscopy is the principal method for examining bulk
samples (such as a rock sample). This technique is relatively straight-
forward and reliable for qualitative identification and characterization of
crystalline substances, including asbestos.
Quantitative analysis of asbestos in a bulk sample is determined by EM.
A small representative portion of rock powder is ground from a bulk sample
and is uniformly dispersed onto a filter media. A small fraction of the
filter is then viewed at high magnification, and asbestos mass and fiber
concentrations are estimated. Careful consideration must be given to sample
preparation, especially during the grinding phase. Chrysotile is usually
present in microveins that tend to disintegrate into small chunks. These
chunks must be given sufficient grinding time to divide into free fibers.
A methodology for analysis of asbestos in rock samples was published by EPA
in December 1978.7 The methodology is summarized in Appendix B.
2.4 ENVIRONMENTAL CONTAMINATION
Asbestos fibers and fiber bundles are released to the atmosphere
primarily by human activity (such as mining, processing, manufacturing,
and the use of asbestos-containing products). Natural phenomena (weathering
and erosion of outcroppings of asbestos-containing rocks) normally contrib-
ute in a small way to asbestos fiber emissions in the local environment.
Very little is known about ambient airborne asbestos fiber concentrations
in the United States and even less is known about how these concentrations
vary geographically and by season. The few environmental studies conducted
prior to 1976 determined airborne asbestos mass concentrations only, thus
are of minimal value in assessing recent airborne fiber concentration
data.
EPA conducted a study to determine ambient asbestos mass concentrations
in 55 cities in the United States. Biweekly air samples were collected
2-6
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and composited for analysis in 3-month periods during 1969 through 1973.
Of the 518 quarterly ambient asbestos mass concentrations measured by EM,
97 percent were less than 100 ng/m3,* 90 percent less than 50 ng/m3 and
38 percent less than 10 ng/m3.8
Mt. Sinai School of Medicine conducted a study for EPA in 1972 to
determine asbestos air concentrations inside and outside of 19 buildings
(in urban settings) fireproofed with asbestos-containing spray materials.
For most of the samples analyzed, there was no significant difference
between asbestos concentrations measured within the buildings and those
measured outside at the same site. The average asbestos mass concentration
(determined by EM) at a given outdoor site varied from 0 to 87 ng/m3.9
The State of Connecticut Department of Environmental Protection
conducted monitoring studies in 1975 and 1976 to determine ambient
concentrations throughout the State. Asbestos mass concentrations at
rural and urban sites generally ranged below 10 ng/m3. At sites located
near industrial sources of asbestos, airborne concentrations averaged
about 30 ng/m3.10
2.5 ASBESTOS FIBER AERODYNAMICS
As shown in Figure 2-2, the length of an asbestos fiber may range
from less than 0.1 micrometer to several tens of micrometers. As previously
discussed, individual fibrils can be as thin as 0.02 urn. The extremely
small size of asbestos fibers indicates two significant fiber
characteristics: aerodynamic transport potential and respirability.
Based on Stokes1 Law, an airborne fiber will settle downward at a
rate determined by its mass, shape, size, and axis attitude. Fiber
settling velocity is strongly dependent upon fiber diameter and to a
lesser extent upon fiber length. Fibers with diameters smaller than 1 urn
can remain airborne for several hours, and fibers with diameters smaller
than 0.1 urn can remain airborne for several days or weeks. Turbulence
(such as the air flow around a moving vehicle) and wind velocity will
prolong settling time and increase the distance traveled by airborne
fibers. Fibers which remain airborne the longest have the greatest
potential to be inhaled.
*1 ng = 10-9 grams.
2-7
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ANGSTROM UNITS
1 * ?.?.'° S> 90 JO 100
I I I I 111!
T
&
i i i mi
\-
i 111 mi
ULTRAVIOLET
1 I I Mill
~l—I I I I Mil—
INFRARED
i r i MIII
i IIKI
| TOBACCO SMOKE—|
VISIBLE LIGHT
SMOG
_ SILT 1 FINE SAND
• CLOUDS and FOG 1
GROUND TALC
-4
-VIRUSES
BACTERIA
|—HUMAN HAJR—|
-ASBESTOS FIBER
i
oo
I VISIBLE TO EYE
I—MACHINE TOOLS (MICROMETERS tic)"
- OPTICAL MICROSCOPES 1
SCANNING and TRANSMISSION ELECTRON MICROSCOPES
X-RAY DIFFRACTION
J I I 1 I III!
j i i i i nil
J I I I I III
|—REAL TIME. MONITORING INSTRUMENTS!
I I I I III ll I I I I I Illl I II
III ll
J I I 1111 l
O.OOOI
oooi
001
01
SIZE RANGE. M.crom«lers
IO
IOO
1000
(I mm)
LENGTH
Figure 2-2. Comparison of asbestos fibers and other particles by size and measurement techniques.
11
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Inhalable particles, particles with diameters smaller than 10 urn,
can be deposited on air passage surfaces all along the respiratory tract.
Fine particles (smaller than 2 urn) are of greater biological significance
than larger particles because they are more likely to be deposited in the
alveolar region of the lung.12
2.6 HUMAN HEALTH EFFECTS ASSOCIATED WITH INHALATION OF ASBESTOS
2.6.1 Introduction
Exposure to asbestos is associated with increased risks of many
diseases, including pulmonary fibrosis (asbestosis), respiratory cancer,
and mesothelioma of both pleura! and peritoneal tissue. These health
effects have been documented in over 90 studies conducted by many
researchers using different groups of occupational workers. (See
reference 13 for a listing of these studies and their principal findings.)
For the purposes of this document, the health effects discussion will
focus on studies that investigated a quantitative dose-response relationship
for disease among workers exposed to only chrysotile asbestos, studies of
asbestos-related health effects resulting from nonoccupational exposure,
and studies that investigated the influence of cofactors such as smoking
habits and age.
2.6.2 Health Hazards of Chrysotile Exposure
2.6.2.1 Asbestosis Mortality. Asbestosis is a chronic, noncancerous,
irreversible disease characterized by hardening and thickening of lung
tissue. Asbestosis has been a major cause of death in groups of workers
exposed to high levels of airborne asbestos. Asbestosis is a progressive
disease that can continue to develop long after a person has been removed
from the source of exposure. Several occupational studies have demonstrated
dose-response relationships between exposure to asbestos and severity of
asbestosis. The dose-response curve for asbestosis mortality among
Canadian chrysotile miners and millers has been described by McDonald
(1979) as a linear relationship, although the author cautions against
extrapolation to very low exposure levels.14
2.6.2.2 Lung Cancer Mortality. Many epidemiological studies have
clearly demonstrated that the risk of lung cancer is increased by exposure
to asbestos. Few researchers, however, have attempted to quantify the
2-9
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risk because of problems in estimating cumulative exposure. Three recent
studies, McDonald (1980), Enterline and Henderson (1979), and Dement et
al. (1980), have investigated a quantitative dose-response relationship
for lung cancer among workers exposed to only chrysotile.15-17 All three
studies suggest that the relationship between cumulative dust exposure
and lung cancer is linear, i.e., the risk of lung cancer is directly
proportional to cumulative exposure. The authors disagree on the magnitude
of increased risk for a given cumulative exposure, particularly for those
workers in the lowest exposure categories. Differences in study design
and the method of exposure estimation probably account for some of the
inconsistencies in the findings of these three studies.
McDonald (1980), who studied chrysotile miners and millers in Quebec,
and Enterline (1979), who investigated mortality of retired maintenance-
service employees of an asbestos manufacturing company, estimated past
dust exposure using work histories and total airborne particulate data
collected by the impinger method.* McDonald included persons exposed to
extremely high airborne fiber levels, thus competing risk (i.e., persons
dying from other causes) may be a problem. Enterline1s study group
consisted only of retirees older than 65 years of age and may represent a
survivor population with less lung cancer risk than the general public.
Workers who died before their 65th birthday were not included in the
study. Both McDonald and Enterline found that the risk of respiratory
malignancies increases directly with increasing cumulative exposure but
that an excess risk is difficult to detect in the groups with least
exposure.
Dement (1980), who studied mortality among chrysotile textile workers,
used asbestos fiber count data (determined by phase contrast microscopy)
to estimate past exposure. Conditions at the textile plant allowed
Dement to evaluate health effects at exposure levels lower than the
levels measured by McDonald or Enterline. Dement1s data suggest a linear
dose-response relationship with no threshold for lung cancer and
*The impinger method involves pulling a volume of air through a small
tube^containing water or alcohol. Particles that settle in the tube are
examined by light microsopy. The impinger method was replaced by the
membrane filter technique in 1971 for determining occupational exposure
to asbestos.
2-10
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nonmalignant respiratory diseases. Lung cancer demonstrated a statistically
significant excess in even the lowest cumulative exposure category. The
risk of lung cancer at a given cumulative dose was also found to be
greater than the risk reported by McDonald and Enterline.
2.6.2.3 Pleural and Peritoneal Mesothelioma. Researchers have
shown that exposure to asbestos can produce mesothelioma of the pleura
(the membrane that surrounds the lungs and lines the thorax) and/or the
peritoneum (the membrane that surrounds the abdominal organs and lines
the abdominal and pelvic cavity). Estimated incidence of mesothelioma in
the United States and Canada ranges from one to six cases per million
population and in general, seem to be higher in cities where asbestos has
been used in the shipbuilding or ship repair industries.18 The disease
is often not detected for 30 to 40 years after initial exposure.
The three studies that quantitatively estimated exposure and lung
cancer among chrysotile workers found low mortality due to mesothelioma;
Dement (1980) found 1 death, McDonald (1980) found 11 deaths, and Enterline
(1979) found 1 death. In another study, Robinson et al. (1979) observed
17 mesotheliomas among 1,040 deaths in a plant using predominantly
chrysotile; however, some crocidolite and amosite were used at the plant.19
Epidemiologists agree that mesothelioma is generally underdiagnosed,
and the proper study of the incidence of this disease requires information
in addition to that which ordinarily appears on death certificates.16
2.6.3 Nonoccupational Exposure to Asbestos
Perhaps the most disconcerting aspect of the relationship between
mesothelioma and asbestos exposure is the documented association of the
disease with apparently low levels of exposure for relatively brief
periods from neighborhood or domestic sources.20 In 1960, Wagner documented
cases of mesothelioma in residents of an asbestos mining area of South
Africa. Many of these individuals had never worked with asbestos; their
exposure was associated with living near the mines, mills, or roadways
along which the asbestos fiber was transported.21 In 1964, Newhouse and
Thompson reviewed 76 cases of reported mesothelioma in London. Roughly
half were found to be former employees of an asbestos manufacturing
facility, 11 were individuals who lived within 1/2 mile of the asbestos
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factory, and 9 were individuals who lived with workmen employed at the
factory.22
More recently, Borow et al. (1973), using hospital records rather
than plant records, reported 72 cases of mesothelioma in the vicinity of
one of the two plants studied by Enterline.23 Upon further investigation
41 of these cases were found to have worked at the plant at some time.
Many of these cases died before the age of 65 and thus were excluded from
Enterline's study groups. Anderson et al. (1976) examined 378 family
members of asbestos workers 25-30 years after the onset of initial asbestos
exposure. Of these, 239 were found to have one or more chest abnormalities.
Five cases of mesothelioma were found in the study group.24 In a
case-control study of all female residents of New York State who died of
mesothelioma between 1967 and 1977, Vianna (1978) found that 15 of
62 confirmed cases had worked in asbestos-related industries and 10 had
husbands or fathers that worked in asbestos related industries.25
Several researchers have shown that asbestos-related diseases are
endemic in some villages in Turkey. Baris (1975) studied 120 cases of
pleura! disease (108 of these were malignant mesothelioma) and found only
2 cases with occupational exposure to asbestos. Of the other 118 cases,
16 cases had a history of environmental exposure to asbestos. No condition
that may result in the inhalation of asbestos was encountered in the rest
of the cases. In such cases, it was suggested that the disease may
result from the ingestion of water, beverages, or food, or from other
sources.26
Yazicouglu (1976) investigated the occurrence of pleura! calcifications
(an early stage of asbestosis, from which mesothelioma may also develop)
in the inhabitants of several towns located in areas of naturally occurring
chrysotile in southeast Turkey. No industrial source of asbestos is
located in the area. A total of 389 individuals (2.6 percent of the
total population) showed pleura! calcifications upon examination.27
2.6.4 Factors That Modify the Risk of Asbestos Induced Disease
2.6.4.1 Smoking Habits. The major factor affecting the risk of
asbestos-induced lung cancer, other than the intensity and duration of
the exposure itself, is the smoking habit of the exposed individual. The
effects of asbestos exposure and cigarette smoke are multiplicative, not
2-12
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simply additive (Selikoff et al., 1980).28 Stopping cigarette smoking is
likely to be of paramount importance in reducing the excess cancer risks
in asbestos-exposed individuals (Gilson, 1976).29
The current consensus of the scientific community is that mesothelioma
occurs with equal frequency among smoking and nonsmoking asbestos workers.
Available studies of asbestos workers are inadequate to determine whether
smoking increases the risk of developing asbestosis.
2.6.4.2 Age. Children exposed to asbestos have a greater lifelong
risk than adults equally exposed. This can be a significant factor when
long latency periods are encountered for diseases such as lung cancer and
mesothelioma. The question of susceptibility has been raised by some
researchers. Kotin (1977) and Wasserman et al. (1979) suggest that
children are more susceptible than adults to carcinogens, including
asbestos.30 31 Other researchers (Doll, 1962; Cole, 1977) state that
special biological susceptibility has not been demonstrated for children
exposed to asbestos.32 33
2.6.5 Fiber Characteristics
2.6.5.1 Fiber Size. A great deal of research has investigated
variations in risk posed by fibers differing in size and chemical
composition. The potential adverse health effects of long fibers (>5 urn
in length) versus short fibers (<5 pm in length) is currently a topic of
debate. So far nothing is known about the importance of fiber size in
the production of bronchial tumors.29 The primary research relating
fiber size to carcinogenic potency applies only to pleural mesothelioma
and involves the direct injection or implantation of fibers into the
pleura of rats. Some evidence suggests that fibers may have to be £10 ^im
in length and less than about 1 urn in diameter in order to produce
mesothelioma.29 Pott (1978), however, states that fibers as short as
3 urn in length have carcinogenic potency.34 Selikoff believes that
fibers less than 3 urn in length can produce tumors. Gross (1974) disagrees
with his colleagues and believes that fibers <5 (jm in length are devoid
of carcinogenic potency.35 Stanton and Layard (1977) investigated the
carcinogenicities of 37 different dimensional distributions of seven
fibrous materials and attained optimum correlation with fibers that
measured less than 0.25 urn in diameter and greater than 8 |jm in length.36
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The authors did not state that fiber sizes outside this optimal range
were devoid of carcinogenic potency.
Presently there is no firm conclusion concerning the relative
activities of short and long fibers. It cannot be said with any confidence
that fibrogenicity drops to negligible proportions at 5 |jm or 1 urn.37
Pott (1978) states that even if the carcinogenic potential of a relatively
short fiber may be weak, many short fibers may induce a tumor as easily
as a few large fibers. The author goes on to say that special problems
arise in calculating carcinogenic potency when bundles of asbestos fibers
are encountered. The possibility of an asbestos fiber bundle splitting
when inhaled can easily increase carcinogenic potency.
2.6.5.2 Fiber Type. Human occupational exposures to all commercial
asbestos fiber types, both individually and in various combinations, have
been associated with high rates of asbestosis, lung cancer, and
mesothelioma. Presently available information indicates that the incidence
of lung cancer does not depend on the type of fiber but mainly on the
dose level. The incidence of mesothelioma appears to be linked to the
type of asbestos.18 There is general agreement that the risk of
mesothelioma is fiber related in the order:
crocidolite > amosite > chrysotile > anthophyllite
The magnitude of the difference between, for example, crocidolite and
chrysotile is not well understood. Timbrell (1973) states that chrysotile
fibers normally are not observed near the pleura because of their curved
shape; however, short chrysotile fibers may behave like crocidolite and
penetrate into deeper regions of the respiratory system.38
2.6.6 Summary of Health Effects
•
Inhalation of asbestos is known to cause asbestosis, lung cancer,
and mesothelioma in humans. Our knowledge of the carcinogenic effects of
asbestos is almost entirely derived from occupational studies. Recent
studies of chrysotile workers that relied on older methods (i.e., impingers)
of estimating dust exposure support the linear dose-response hypothesis
for lung cancer among most exposure groups. The most recent study of
chrysotile workers (Dement et al., 1980) estimated exposure to airborne
asbestos fiber concentrations using phase contrast microscopy and indicated
that there is no threshold to the linear relationship for lung cancer and
2-14
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nonmalignant respiratory diseases. The evidence of asbestos-related
disease in members of asbestos-worker households and in persons living
near asbestos-contaminated areas lends additional support to the
no-threshold, linear dose-response hypothesis.
Smoking habits and age are two important cofactors associated with
increased risk of asbestos-related disease. Currently, there is no
consensus among researchers as to the relative carcinogenic potency of
short versus long fibers. The varying intensity and type of exposure,
the problem of exposure estimation, and the influence of cofactors make
it extremely difficult to specify safe exposure levels for the general
public. Consequently, EPA believes that public exposure to airborne
asbestos be reduced to the greatest extent practical.
2-15
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2.7 REFERENCES FOR CHAPTER 2
1. Control Techniques for Asbestos Air Pollutants. Publication AP-117.
U.S. Environmental Protection Agency. Research Triangle Park, N.C.
February 1973.
2. Letter from Forshey, D. R. , U.S. Bureau of Mines, to Goodwin, D. R.,
EPA. April 9, 1981. p. 5. Response to Working Group mail out.
3. Levine, R. J. Asbestos: An Information Resource. National Cancer
Institute. Bethesda, Md. PB-293-736. May 1978. 150 p.
4. Workplace Exposure to Asbestos: Review and Recommendations. NIOSH-OSHA
Asbestos Work Group. April 1980. 62 p.
5. Electron Microscopic Measurement of Airborne Asbestos Concentrations--
A Provisional Methodology Manual. U.S. Environmental Protection
Agency. Research Triangle Park, N.C. Publication No. EPA 600/2-77-178.
Revised June 1978. 48 p.
6. Evaluating and Optimizing the Electron Microscope Method for
Characterizing Airborne Asbestos. U.S. Environmental Protection
Agency. Research Triangle Park, N.C. EPA 600/2-78-038. June 1978.
182 p.
7. Miller, J. L. Identification of Selected Silicate Minerals and
Their Asbestiform Varieties by Electron Optical and X-Ray Techniques.
U.S. Environmental Protection Agency. Research Triangle Park, N.C.
Publication No. EPA 600/J-78-136. December 1978. 12 p.
8. Memorandum from Scaringelli, R., EPA:ESAS to Chief, EPA:SDB.
January 8, 1974. p. 7. Concentration of Asbestos in United States
cities.
9. Asbestos Contamination of the Air in Public Buildings. U.S.
Environmental Protection Agency. Research Triangle Park, N.C.
Publication No. EPA-450/3-76-004. October 1975.
10. Bruckman, L. and R. Rubino. Asbestos: Rationale Behind a Proposed
Air Quality Standard. APCA Journal. 25:1207-1215. December 1975.
11. Asbestos-Containing Materials in School Buildings. U.S. Environmental
Protection Agency. Research Triangle Park, N.C. Publication
No. EPA-450/2-78-014. March 1979.
12. Lippmann, M. Inhalation, Deposit and Clearance of Particles. New
York University Institute of Environmental Medicine. New York, New
York. (Presented at the proceedings of the National Workshop on
Substitutes for Asbestos. July 14-16, 1980). U.S. Environmental
Protection Agency. Washington D. C. Publication No. EPA 560/3-80-001.
November 1980. pp. 283-312.
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13. Revised Recommended Asbestos Standard. U.S. National Institute of
Occupational Safety and Health (NIOSH). Washington, D. C.
December 1976. pp. 53-57.
14. McDonald, J. C., and F. D. Kiddell. Mortality in Canadian Miners
and Millers Exposed to Chrysotile. Annals of the New York Academy
of Science. 330:1-9. 1979.
15. McDonald, J. C., et al. Dust Exposure and Mortality in Chrysotile
Mining. British Journal of Industrial Medicine. 37:11-24. 1980.
16. Henderson V., and P.E. Enterline. Asbestos Exposure: Factors
Associated With Excess Cancer and Respiratory Disease Mortality.
Annals New York Academy of Sciences, pp. 117-125. 1979.
17. Dement, J. M., R. L. Harris, M. J. Symons, and C. Shy. Estimates of
Dose-Response For Respiratory Cancer Among Chrysotile Asbestos
Textile Workers. (Presented at the Fifth International Symposium on
Inhalable Particles and Vapors. Cardiff, Wales. September 1980).
pp. 10.4-1 thru 10.4-23.
18. Zielhuis, R. L. Public Health Risks of Exposure to Asbestos.
Report of a Working Group of Experts Prepared for the Commission of
the European Communities. Directorate-General for Social Affairs,
Health and Safety Directorate. Luxembourg, Pergamon Press. 1977.
143 p.
19. Robinson, et al. Mortality Patterns, 1940-1975 Among Workers Employed
in an Asbestos Textile, Friction, and Packing Products Manufacturing
Facility. In: Dust and Diseases, Lemen R.A., and Dement, J. M.,
(eds.) Park Forest South, Illinois, Pathatox Publishers Inc.,
1979. 131 p.
20. Becklake, M. R. Asbestos Related Diseases of the Lung and Other
Organs: Their Epidemiology and Implications for Clinical Practices.
American Review of Respiratory Disease. JJ4:210. 1976.
21. Wagner, I. C., C. A. Sleggs, and P. Marchand. Diffuse Pleural
Mesothelioma and Asbestos Exposure in North Western Cape Province.
British Journal of Industrial Medicine. V7:260~27"L 1960.
22. Newhouse, M. L. and H. Thompson. Mesothelioma of Pleura and
Peritoneum Following Exposure to Asbestos in the London Area.
British Journal of Industrial Medicine. 22:261-269. 1965.
23 Borow, M. A., et al. Mesothelioma Following Exposure to Asbestos:
A Review of 72 Cases. Chest. 64:641-646. 1973.
24. Anderson, H. R., et al. Household Contact Asbestos Neoplastic Risk.
Annals of the New York Academy of Science. 271:311-323. 1976.
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25. Vi'anna, N. J. and A. K. Polan. Non-occupational Exposure to Asbestos
and Malignant Mesotheliomas in Females. Lancet. J:1061. 1978.
26. Ban's, Y.I. Pleural Mesotheliomas and Asbestos Pleurisies Due to
Environmental Asbestos Exposure in Turkey: An Analysis of 120 Cases.
Hacettepe Bulletin of Medicine. Vol. 8, No. 4. pp. 165-185.
December 1975.
27. Yazialoglu S. Pleural Calcification Associated with Exposure to
Chrysotile Asbestos in Southeast Turkey. Chest. 70:43-47. July 1976.
28. Selikoff, et al. Mortality Effects of Cigarette Smoking Among
Amosite Factory Workers. Journal of National Cancer Institute.
65:507-513. 1980.
29. Gilson, J. C. Asbestos Cancers as an Example of the Problem of
Comparative Risk. INSERM. 55:107-166. 1976.
30. Kotin, P. Briefing Before the Consumer Product Safety Commission.
22 FR 38786. July 29, 1977.
31. Wassermann, M., et al. Mesothelioma in Children. (Presented at the
Symposium on the Biological Effects of Mineral Fibers. Lyon, France.
September 25-27, 1979.)
32. Doll, R. Susceptibility to Carcinogenic!ties at Different Ages.
Geron Clin. 4:211-221. 1962.
33. Cole, P. Cancer and Occupation. Cancer. 39:1788-1791. 1977.
34. Pott, F. Some Aspects of the Dosimetry of the Carcinogenic Potency
of Asbestos and Other Fibrous Dust. Staub-Reinhalt Luft. 1_2:486-490.
December 1978.
35. Gross, P. Is Short-Fibered Asbestos Dust a Biological Hazard?
Archives of Environmental Health. 29:115-117. August 1974.
36. Stanton, M. and M. Layard. The Carcinogenicity of Fibrous Minerals
NIOSH. Bethesda, Maryland. (Presented at Proceedings of the Workshop
on Asbestos: Definitions and Measurement Methods. Gaithersburg,
Maryland, July 18-20, 1977). pp. 143-151.
37. Selikoff, I. and D. Lee. Asbestos and Disease. Academic Press.
1978. p. 428.
38. Timbrel!, V. Physical Factors as Etiological Mechanisms. Biological
Effects of Asbestos. Lyon, France. IARC. p. 295. 1975.
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3. EXPOSURE ASSESSMENT FOR CRUSHED STONE CONTAINING CHRYSOTILE
3.1 DETECTION OF ASBESTOS EMISSIONS IN MARYLAND IN 1976
In September 1976, asbestos was identified as a component of the
crushed stone used to surface many unpaved roads in Montgomery County,
Maryland. The source of the crushed stone was a quarry in Rockville,
Maryland, located in a serpentinite rock deposit. Atmospheric particulate
samples collected near an unpaved road surfaced with crushed serpentinite
were analyzed with an electron microscope and showed chrysotile mass
concentrations about 1,000 times greater than those typically found in
urban air.1 Dust collected from the quarry's stockpile and a nearby
road contained from 0.1 to 0.7 percent chrysotile by weight.2
Several air monitoring programs were conducted in 1976 and 1977 by
the State of Maryland, the Montgomery County DEP, and EPA to measure
airborne chrysotile concentrations in Montgomery County associated with
different uses of crushed serpentinite and to evaluate various EM
preparation and analysis procedures used by different laboratories.3-7
EPA concluded from the test data that:
1. Uses of serpentinite that result in the generation of visible
dust also result in elevated asbestos levels;
2. All laboratories should use the same EM preparation and analysis
procedures for determining airborne asbestos concentrations; and
3. The particular quarry in question was not a major source of
airborne asbestos in the vicinity.
Upon consideration of these conclusions and supplementary analyses
by EPA personnel, the Agency recommended that the State of Maryland and
Montgomery County DEP act to control chrysotile emissions from unpaved
roads surfaced with serpentinite. The State and County responded by
paving all such roads (92 miles) in the county. In addition, crushed
serpentinite used in parks and playgrounds was removed or covered.
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Montgomery County DEP conducted additional air monitoring of the
following sources in 1977-1978 to assess asbestos emissions from other
uses of crushed sepentinite: a lightly traveled unpaved road, an unpaved
road treated with a dust suppressant, driveways, playgrounds, unpaved
parking lots, and residential paved roads. Asbestos fiber concentrations
ranged from 0.002 to 3.3 fibers/ml.8 From the site-specific results,
Montgomery County DEP concluded that "elevated asbestos levels occurred
only on unpaved road surfaces or bare stone surfaces with moderate-to-heavy
vehicular traffic creating dust conditions."8 The terms "elevated asbestos
levels" and "moderate-to-heavy vehicular traffic" were not defined in the
report.
3.2 NATIONWIDE INVESTIGATION OF CHRYSOTILE EMISSIONS FROM ROADWAYS AND
QUARRIES
3.2.1 Advanced Notice of Proposed Rulemaking
In the summer of 1977, EPA requested assistance from the Bureau of
Mines (BOM), the United States Geological Survey (USGS), and the Mining
Enforcement and Safety Administration (MESA)* to determine the extent to
which quarrying operations were being conducted nationwide in asbestos-
containing rock deposits. MESA initiated a long-term study to identify
mining operations with asbestos emissions that exceed the present MSHA
standard for airborne asbestos (see Appendix A, Table A-3). MSHA's
investigation, which includes several thousand mining operations located
in metamorphic rock deposits, has not yet been completed.
EPA's survey of the crushed stone industry concentrated on quarries
located in serpentinite rock deposits because these deposits are known to
contain chrysotile. On November 10, 1977, EPA published an Advance
Notice of Proposed Rulemaking (42 FR 58543) stating that a standard
regulating the production and use of serpentinite rock would be proposed
if the Agency determined that the production and use of such stone causes
asbestos emissions proximate to the public in a number of locations.
*MESA was renamed the Mine Safety and Health Administration (MSHA) when
the agency was transferred from the Department of Interior to the
Department of Labor pursuant to the Federal Mine Safety and Health
Amendments Act of 1977.
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3.2.2 EPA Quarry Survey
Serpentinite rock deposits occur throughout much of the Appalachian
Mountains and in some portions of the Western coastal ranges. A list of
the 23 States that have known serpentinite deposits is shown in Table 3-1.
Quarries located in serpentinite deposits were identified by transparent
map overlays that "matched" known quarry locations with known deposits of
serpentinite. Maps showing serpentinite rock deposits in the United
States were prepared by the USGS for this purpose. BOM provided map
overlays (of the same scale) that indicated quarry locations. Supplemental
information on quarry locations was supplied by the State Aggregate
Association and EPA's National Emissions Data System (NEDS). Quarries
located within a 10-mile radius of a known serpentinite deposit or located
in a strata of rock between known serpentinite deposits were considered
to be potential sources of chrysotile.9 EPA requested that State geologists
review the mapping procedure for locating potential sources of chrysotile
within their respective States and provide information about specific
quarries identified by the mapping procedure. State geologists confirmed
that 8 quarries positively produce crushed serpentinite containing
chrysotile and suspected that 111 other quarries may be producing this
material.10-13 Petrographic analysis of rock samples from the 111 suspect
quarries identified 8 additional quarries that contain chrysotile.14 A
list of the 16 quarries producing crushed serpentinite and the range of
chrysotile concentration in their product are shown in Table 3-2.
Field investigations determined that only 5 of the 16 quarries in
Table 3-2 produce crushed serpentinite which is used for surfacing unpaved
public roads.16-21 The five quarries are listed in Table 3-3 along with
the number of road miles surfaced with serpentinite and the estimated
number of nearby residents. Approximately 400 miles of public roads in
four States are surfaced with crushed serpentinite (predominantly from
three of the five quarries). Approximately 6,500 people nationwide
reside within approximately 200 feet of these roads and are the persons
most likely to be exposed to chrysotile emissions from the roadways.
Population figures were estimated from county maps and field surveys.
EPA conducted an additional field investigation of Federal lands and
found that the USFS and the Bureau of Land Management (BLM) operate a
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TABLE 3-1. STATES WHERE DEPOSITS OF
SERPENTINITE ROCK OCCUR
Alabama
Alaska
Arizona
California
Connecticut
Georgia
Idaho
Maine
Maryland
Massachusetts
Montana
Nevada
New Hampshire
New Jersey
New York
North Carolina
Oregon
Pennsylvania
Rhode Island
South Carolina
Vermont
Virginia
Washington
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TABLE 3-2. QUARRIES PRODUCING CRUSHED SERPENTINITE CONTAINING CHRYSOTILE
CONFIRMED THROUGH PETROGRAPHIC AND/OR EM ANALYSIS
OF STONE PRODUCT2 15 22
Location
Quarry name
Azevedo
Bluemont
Cedar Hill
Delight
Dumbarton
Ghilotti Brothers
Hillsdale
Rockville
Cardinal
George Reid
Woods Creek
Morris Pit
Six Bits
(Red Hill)
Chancellor Pit
(Unnamed)
(Unnamed)
County
Santa Clara
Baltimore
Lancaster
Baltimore
Alameda
Marin
Santa Clara
Montgomery
Grayson
Tuolumne
Tuolumne
Coos
Tuolomne
Josephine
Jackson
(Section 11 ,
Township 34 South,
Range 4 West)
Josephine
(Section 29,
Township 36 South,
Range 7 West,
Siskayou National
Forest)
State
California
Maryland
Pennsylvania
Maryland
California
California
California
Maryland
Virginia
California
California
Oregon
California
Oregon
Oregon
Oregon
Chrysotile
concentration
percent weight
0.50-1.60
b
0.30-2.40
0.05-0.40
b
0.10-1.40
0.20-2.70
0.03-0.70
0.02-1.2
b
0.01-0.70
b
b
b
b
b
Ownership
Private
Private
Private
Private
Private
Private
Private
Private
Private
Private
Private
Private
Tuolumne
County
Oregon
State
BLM
USFS
.Determined by electron microscopy.
The presence of chrysotile was qualitatively determined by petrographic
analysis. No quantitative data are available.
3-5
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TABLE 3-3. UNPAVED ROADS SURFACED WITH QUARRIED SERPENTINITE
AND THE ESTIMATED NUMBER OF NEARBY RESIDENTS3 D
Quarry
Bluemont
Cedar Hills
Cardinal
Woods Creek
Six Bits
Total
Counties where
serpentinite is
used for surfacing
unpaved roads
Baltimore County, Md.c
Harford County, Md.
Grayson County, Va.
Allegheny County, N.C.
Tuolumne County, Calif.
Tuolumne County, Calif.
Miles of
unpaved roads
surfaced with
serpentinite
16
64
100
220
2
3
405
Estimated No. of
nearby residents
650
2,750
1,200
1,700
20
30
6,350
aNearby residents are those people whose homes are located within
.approximately 200 ft of a serpentinite-surfaced road.
In 1978 and 1979 the Montgomery County Department of
Transportation paved all county roads (92 miles) surfaced with crushed
serpentinite. The number of nearby residents was not estimated.
°Baltimore County plans to hard-surface these roads in 1981.
3-6
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number of small quarries in areas of California and Oregon where serpen-
tinite deposits are common. These quarries produce stone to maintain
logging roads on Federal land that are used by haul vehicles during
intermittent harvest seasons. In the general vicinity of these quarries
there are roughly 1,000 miles of native stone/soil roads over serpentinite
outcroppings that are not surfaced with quarry material. A massive out-
cropping of serpentinite is known to occur in San Benito County, California,
where BLM maintains the 43,000 acre Clear Creek Federal Recreation Area.
Clear Creek had over 41,000 users in 1975, 85 percent of which were
operators of off-road vehicles.23 Serpentinite data concerning Federal
lands are shown in Table 3-4.
BLM, USFS, and the Department of Interior are conducting investigations
to determine the occurrence and use of serpentinite on additional Federal
lands. In response to the known data, the USFS has announced that asbestos
sampling will be conducted in 1981 at quarry sites and adjacent roads in
several of the National Forests listed in Table 3-4. The BLM regional
office in Sacramento, California, is preparing an environmental assessment
report for the Clear Creek Recreation Area and will hold public hearings
in 1981 to discuss management alternatives for the popular recreation
area.
3.3 ASBESTOS SAMPLING, 1979
EPA conducted an extensive air monitoring program in 1979 to measure
chrysotile emissions that result from the production and use of crushed
serpentinite and to characterize the variables that influence those
emissions. Data from the monitoring program were used to evaluate the
performance of the provisional method for electron microscope measurement
of asbestos concentrations in ambient air.
Air monitoring was conducted at six sites:
1. Holy Cross Road, Harford County, Maryland;
2. McNabb Road, Harford County, Maryland;
3. Cedar Hills Quarry, Lancaster County, Pennsylvania;
4. Woods Creek Quarry, Tuolumne County, California;
5. Duffy Road, Tuolumne County, California; and
6. Clear Creek Federal Recreation Area, San Benito County, California.
3-7
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TABLE 3-4. SERPENTINITE QUARRIES AND UNPAVED ROADS
LOCATED ON FEDERAL LANDS19 24
Location
Quarries on
Federal land
producing
serpentinite
Miles of
unpaved roads
surfaced with
quarried
serpentinite
Miles of
roads over
native
serpentinite
outcroppings
Klamath
National Forest (NF)
California
65
390
Six Rivers NF
California
Shasta-Trinity NF
California
Mendocino NF
California
Tahoe NF
California
Los Padres NF
California
Plumas NF
California
BLM-Medford District
Oregon
BLM-Clear Creek
Recreation Area
California
4
2
1
1
0
0
20-30
0
180
28
40
0
0
0
NAb
0
380
0
42
0
0
60
NA
c
Unpaved roads in National forests are primarily used by haul vehicles
.during intermittent harvesting operations.
°NA = not available.
Much of this 43,000-acre recreation area is located in serpentinite
outcroppings and is used by off-road-vehicles.
3-8
-------
Airborne participate samples were collected in the vicinity of Cedar
Hills Quarry and Woods Creek Quarry to determine ambient chrysotile
concentrations that result from the production of crushed serpentinite.
Data from the Holy Cross Road site and the McNabb Road site were used to
assess the airborne chrysotile concentrations to which local residents
may be exposed and to characterize the variables that influence chrysotile
emissions from roadways. Both roads are surfaced with crushed serpentinite
produced by the Cedar Hills Quarry. Air sampling was conducted in the
Clear Creek Recreation Area to measure ambient chrysotile concentrations
to which visitors may be exposed.
A summary report of the monitoring program is contained in Appendix B.
The program's major conclusions are summarized below.
3.3.1 Conclusions
1. Statistical evaluation of the results indicate that ambient
chrysotile fiber concentrations can be measured with an acceptable degree
of precision. The coefficient of variation for intra- and interlaboratory
analysis of split and colocated samples ranged from 34 percent to 72 percent
(see Table B-19).
2. Analyses indicate that airborne chrysotile fiber concentrations
downwind of unpaved roads surfaced with crushed serpentinite, containing
trace amounts of chrysotile and subject to light-to-moderate traffic, are
significantly higher than concentrations upwind of those roads. The
geometric mean for 16 upwind samples from the unpaved roads in Harford
County, Maryland, was 0.16 fiber/ml. Chrysotile fiber concentrations
measured at different distances downwind of the roadways ranged from 0.04
to 2.52 fibers/ml. These downwind concentrations resulted after
approximately 30 vehicle passes (at 30 mph) were made across the dry,
unpaved road surfaces during a 2-hour sampling period.
3. No statistically significant relationship was found for fiber
concentrations versus receptor distance downwind, chrysotile content of
the roadstone, traffic volume, or wind speed. No conclusions can be
drawn concerning the influence of these variables on chrysotile emissions
from roadways.
4. Results support the conclusion made earlier by the Montgomery
County DEP that serpentinite quarries are not a major source of airborne
3-9
-------
asbestos to the surrounding area. Chrysotile concentrations measured
near two serpentinite quarries ranged from 0.01 to 0.35 fiber/ml with a
geometric average of 0.04 fiber/ml.
5. The chrysotile concentrations reported in this study underestimate
the true potential for asbestos exposure from unpaved roads surfaced with
serpentinite. TEM analysis revealed that many of the particulate samples
contained bundles and sheaves of fibers that have the potential to split
into many fibrils. The reported fiber concentrations are based only upon
the observable fibers with length-to-width ratio of 3 or greater. Numerous
fibers may eventually be released from a single bundle of fibers. Also,
chrysotile fibers that were obscurred by the presence of other material
on the filter preparations could not be counted.
6. Fiber concentrations reported in this study are not comparable
to fiber concentrations determined by phase-contrast microscopy. Nearly
all the fibers detected were short, thin fibers (less than 5 urn in length
and less than 0.1 urn in diameter) that would not be counted by phase
contrast microscopy because of procedural and analytical limitations.
7. Chrysotile fiber concentrations near campsites in the Clear
Creek Recreational Area are approximately 100 times greater than average
ambient background concentrations observed at the test sites located in
Harford County, Maryland.
3.4 EPA RESPONSE TO ADVANCE NOTICE OF PROPOSED RULEMAKING (42 FR 58543)
Monitoring studies indicate that serpentinite quarries are not a
major source of airborne asbestos to the surrounding area. However, the
use of serpentinite to surface unpaved roads results in local chrysotile
concentrations significantly higher than background levels. From a
nationwide survey of the quarry industry, it has been determined that
quarried serpentinite is used to maintain a small number of unpaved
public roads in a few locations in the United States. Approximately
6,500 people are likely to be exposed to chrysotile emissions from these
roads.
EPA believes that asbestos emissions from unpaved roads and other
dusty sources (such as unpaved parking lots) should be reduced to the
greatest extent practical. The level of asbestos emissions as well as
3-10
-------
the most appropriate method to control those emissions varies with location.
EPA has concluded that local, State, and Federal agencies that maintain
these roads are in the best position to assess local conditions and
implement the most appropriate control measures.
3-11
-------
3.5 REFERENCES FOR CHAPTER 3
1. Rohl A. M., A. M. Langer, and I. J. Selikoff. Environmental Asbestos
Pollution Relating to Use of Quarried Serpentinite Rock. Science.
9:1319-1322. June 17, 1977.
2. Memorandum from Miller, J. L , EPA:ESRL to Roy, S. L., EPA:ESED.
April 11, 1977. p. 2. Quantitative measurement of asbestos
(chrysotile) in Rockville, Maryland quarry sample.
3. Sampling data presented at the Asbestos Meeting of the National
Institute of Health. June 8, 1977.
4. Letter and attachments from Cooney, W. W., Maryland Department of
Health and Mental Hygiene, to Fitzgerald, D., EPA. February 25, 1977.
Transmittal of Maryland sampling results for 22 air filters.
5. Analysis of Ten Filter Samples From State of Maryland Department of
Health and Mental Hygiene: Rockville Quarry. Walter C. McCrone
Associates, Inc. Chicago, Illinois. June 1977.
6. Comparison of Ambient Asbestos Levels Determined by Various
Laboratories. U.S. Environmental Protection Agency. Research
Triangle Park, N.C. September 1977.
7. Montgomery County Asbestos Study. U.S. Environmental Protection
Agency. Research Triangle Park, N.C. October 1977.
8. Asbestos in the Environment of Montgomery County, Maryland, 1981.
Division of Pollution Control, Montgomery County Department of
Environmental Protection. Rockville, Maryland. February 1981.
9. Procedure for Identification of Rock Quarries That Contain Asbestos.
U.S. Environmental Protection Agency. Research Triangle Park, N.C.
Publication No. EPA 450/3-78-032. July 1978.
10. Letter from Gay, T. E. , Jr., California Division of Mines and Geology,
to Goodwin, D. R., EPA. October 13, 1977. Response to request to
identify California quarries located in serpentinite rock deposits.
11. Letter from Beaulieu, J. D., Oregon Department of Geology and Mineral
Industries, to Goodwin, D. R., EPA. December 5, 1977. Response to
request to identify Oregon quarries located in serpentinite rock
deposits.
12. Letter from Weaver, K. N., Maryland Geological Survey, to Goodwin,
D. R., EPA. February 1, 1978. Response to request to identify
Maryland quarries located in serpentinite rock deposits.
13. Letter from Wheatly, L. F., Virginia Department of Labor and Industry,
Division of Mines and Quarries, to Fitzgerald, D. J., EPA. April
24, 1978. Response to request to identify Virginia quarries located
in serpentinite rock deposits.
3-12
-------
14. Asbestos Rock Quarries--Mineralogical Analysis of Crushed Stone
Samples. U.S. Environmental Protection Agency. Research Triangle
Park, N.C. Publication No. EPA 450/3-79-031. July 1979. 155 p.
15. Asbestos Analyses of Crushed Stone Samples. U.S. Environmental
Protection Agency. Research Triangle Park, N.C. Publication
No. EPA-450/3-80-039. April, 1981. 378 p.
16. Memo from Mumma, C. E., Midwest Research Institute, to Wood, G. H.,
EPA. March 12, 1979. Trip report for visit to Baltimore and
Montgomery County, Maryland, to identify roads surfaced with
serpentinite.
17. Memo from Warner, R. A., Midwest Research Institute, to Wood, G. H.,
EPA. May 9, 1979. Trip report for visit to Maryland and Pennsylvania
to identify roads surfaced with serpentinite.
18. Memo from Mumma, C. E., Midwest Research Institute, to Wood, G. H.,
EPA. June 29, 1979. Trip report for visit to San Francisco and
Sonora, California, to identify roads surfaced with serpentinite.
19. Memo from Warner, R. A., Midwest Research Institute, to Wood, G. H.,
EPA. July 9, 1979. Trip report for visit to Oregon and California
to assess the use of crushed stone containing chrysotile.
20. Memo from Serra, R. K., Midwest Research Institute, to Wilson, R.,
EPA. April 29, 1980. Trip report for visit to Albemarle County,
Virginia, to collect samples of crushed serpentinite used on county
roads.
21. Telecon: Serra, R. K., Midwest Research Institute, with Mr. Sprinkle,
Baltimore County, Maryland, Highway Department. August 1, 1979.
Status of Baltimore County roads surfaced with serpentinite.
22. Marklund, D., et.al. Analysis of Crushed Rock Sample Specimens for
Measurement of Asbestos Content by Electron Microscopy. Environmental
Services Laboratory. University of Minnesota, Duluth, Minnesota.
11 p.
23. Cooper, W. C., et al. Chrysotile Asbestos in a California Recreational
Area. Science. 206:685-688. November 1978.
24. Neirinckx, J. Asbestos Status Report. U.S. Forest Service.
August 20, 1979. 4 p.
3-13
-------
4. EMISSION CONTROL ALTERNATIVES AND ADMINISTRATIVE OPTIONS
4.1 INTRODUCTION
This chapter discusses various control alternatives for reducing or
eliminating chrysotile emissions generated by vehicular traffic on unpaved
roads surfaced with serpentinite. The administrative policies and
regulations that could be modified to prevent future surfacing of roads
with serpentinite are also discussed. Because economic and meteorological
conditions vary widely throughout the United States, EPA believes that
local, State, and Federal agencies should perform their own analyses to
determine the most cost effective dust control strategy for reducing
local asbestos emissions.
4.2 EMISSION CONTROL ALTERNATIVES
Studies have shown that elevated airborne asbestos concentrations
occur near unpaved, untreated roads surfaced with serpentinite when
traffic creates dusty conditions. Measures which reduce particulate
emissions (dust) from these roads will also reduce asbestos emissions.
The factors that influence dust emissions resulting from vehicular use of
unpaved roads include: miles of unpaved roads; vehicle speed, weight,
and number of wheels; average daily traffic on each road; silt content of
the road surface; and the number of dry days per year. Particulate
emissions can be reduced by (1) reducing the vehicular variables through
the use of traffic controls and (2) reducing the silt variable by applying
dust suppressants, by adding gravel, or by paving.
Various emission control alternatives are compared in Table 4-1 and
are discussed in detail in the remainder of this chapter. Secondary
benefits of the various alternatives, such as reduced maintenance costs,
are not considered in the cost figures. Two other factors, road safety
and the cost of money, also are not included in the calculations. The
4-1
-------
ro
TABLE 4-1. A COMPARISON OF CONTROL ALTERNATIVES
FOR REDUCING CHRYSOTILE EMISSIONS FROM UNPAVED ROADS1-18
Control Initial cost
option $1 ,000/ii*
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Stone replacement
Single-coat chip seal
Triple-coat chip seal
Petroleum products
Lignosulfonate
Calcium chloride
Water and wetting agents
Speed control
30-10 mph
Speed control
30-20 mph
Stone replenishment
32
5-8
20-37
4-11
3.6-8.5
3-5
27-42
0
0
21
Annual
maintenance
cost
$1 ,000/mt
0.6-2.5
0.8
0.2
4-11
3.6-8.5
3-5
27-42
0
0
0.6-2.5
Ten-year
Ten-year total cost
total cost $l,000/«i
$1 ,000/ai (mtdrange)
37-55
21-30
22-39
40-110
36-85
30-50
270-420
96-304*
24-76*
26-44
46
26
31
75
61
40
345
199
50
35
Annual
efficiency
percent
chrysotile.
controlled
100
90-99.9
90-99.9
60-85
60-80
60-80
40-60
66
33
f
Frequency
of c
application
1 time
3 times/
10 yr
1 time/
10 yr
2 times/yr
1 time/yr
3 times/yr
3 times/wk
--
«
1 time/yr
Adverse
environ-
mental
impacts
None
None
None
None
None
Yes
None
None
None
None
Ease of
driving
No change
Excellent
Excellent
Good
Good
Good
Fair
No change
No change
No change
*Costs include labor and surface preparation. All cost figures are in 1979 dollars.
Assumed to be proportional to efficiency in controlling dust emissions.
^Applications necessary to maintain annual efficiency rating.
The cost of lignosulfonates may be significantly reduced If a local supply can be secured at nominal cost.
^Estimated social cost of time "lost" by traveling slower. An average daily traffic volume of 100 vehicles was assumed.
frepresents the value of lost time for Individual ($4 per car-hour) and commercial drivers ($12.50 per vehicle-hour).
'Not known.
The range
-------
wide ranges in the cost estimates and control efficiencies for some of
the control alternatives reflect the influence of regional variation.
4.2.1 Stone Replenishment
Chrysotile emissions from roads surfaced with serpentinite can be
reduced by the addition of several inches of crushed stone that does not
contain chrysotile. This action would reduce the concentration of chrysotile
in the surface material and, therefore, also reduce the rate at which
chrysotile fibers are released to the atmosphere. No adverse environmental
impacts are associated with stone replenishment.
The cost of adding a 10-cm (4-in.) crushed stone surface to a 6.4-meter-
wide (20-ft-wide) secondary road is approximately $13,000/km ($21,000/mi).
This figure assumes that 2,140 Mg/km (3,100 tons/mi) of stone would be
needed at a cost of $7.20/Mg ($7/ton) for the stone "in place." One-half
the cost is for labor, equipment, and transportation.1
4.2.2 Stone Replacement
In some areas chrysotile emissions could be eliminated by removing
the chrysotile-containing stone from the surface of the road. No adverse
environmental impacts are foreseen from implementation of this alternative
provided that worker exposure to dust is minimized during the removal
process and the removed stone is not reused where it is subjected to
abrasion likely to generate dust.
The Harford County (Maryland) Road Department estimates the cost of
stone removal in their area to be over $6,250/km ($10,000/road-mi). This
figure does not include the cost of replacing the stone. Total cost of
resurfacing a mile of road with crushed stone is estimated to be $32,000.2
4.2.3 Paving
Paving includes the use of a variety of surfacing materials. Three
general types of pavement are bituminous concrete, concrete, and chip
seals.
4.2.3.1 Bituminous Concrete and Concrete Surfaces. Roads constructed
with these two materials are designed to support heavy traffic. Because
of their high initial cost, these pavements are not generally used to
surface secondary roads. Bituminous concrete is a hot mixture of asphalt
and a well-graded aggregate, and concrete is a composite material of
4-3
-------
cement, water, and aggregate. Concrete requires less maintenance and is
more durable than bituminous surfaces.
4.2.3.2 Chip Seal Surfaces. Chip seal surfaces, also called macadam,
consist of one to three layers of aggregate and asphalt. The asphalt is
sprayed over each aggregate layer, top-dressed with a covering of smaller
stones, and compacted. Finished chip seals usually are from 1 to 4 cm
thick. Two types of asphalt are used for chip seal surfaces: emulsified
asphalt and cutback asphalt. Emulsified asphalts contain an emulsifying
agent, water, and asphalt. Asphalt emulsions are cured by the evaporation
of water from the mixtures. Cutback asphalts are formed by adding various
amounts of volatile solvents (up to 30 percent kerosene or naphtha) to
the bituminous mixture. The asphalt hardens as the solvents evaporate
into the atmosphere.
No adverse environmental impacts are foreseen if emulsified asphalts
are used in chip seal construction; however, care should be taken when
handling emulsifying agents since most are corrosive to the skin. Many
of the asphalt emulsions (cationic emulsions) can be applied to wet or
dry surfaces and are unlikely to be washed away by sudden rain showers.
Other emulsions (anionic emulsions) can more readily be flushed from the
roadways by rain into receiving streams. Emulsified products are generally
stable, nonvolatile, and relatively nontoxic. The use of cutback asphalts
should be avoided because of air pollution considerations and because
they are highly flammable.
Chip-sealing any unpaved road binds the surface material and prevents
loose material below the surface from being emitted to the atmosphere.
Annual dust control efficiencies of paved surfaces have been estimated by
researchers to range from 90 to 99.9 percent.3 A typical triple-seal
chip surface 3.75 cm (1.5 in.) thick can be expected to serve up to
10 years before additional surface treatment is required. Single chip
seal coats generally require a second chip seal after 1 year and another
seal in approximately 5 years.4
4.2.3.3 Costs. Bituminous concrete costs from $34,000 to $63,000/km
($55,000 to $100,000/mi) for a 7.6-cm (3-in.) surface over a two-lane
area. Costs for the same area for a concrete surface can be up to three
times as high. The cost of a single chip seal coat over a crushed stone
4-4
-------
road base ranges from $3,125 to $5,000/km ($5,000 to $8,000/mi). A
triple coat treatment of three layers of aggregate and asphalt costs from
$12,500 to $21,900/km ($20,000 to $35,000/mi).
4.2.4 Traffic Controls
Dust emissions generated by vehicles are proportional to vehicle
speed.5 Thus, lowering the speed limit on an unpaved road will reduce
the dust emissions generated by traffic on the road. To a lesser degree,
the number of wheels and weight of a vehicle also influence the amount of
dust generated. No adverse environmental impacts are foreseen in
implementing traffic controls.
4.2.4.1 Effectiveness. Theoretically, a 66 percent reduction in
the level of dust could be achieved solely by reducing speed limits from
30 mph to 10 mph. Preventing one 10-wheel truck (weighing 20 tons) from
traveling on an unpaved road effectively reduces the emissions that would
be generated by eight 4-wheel (2-ton) vehicles traveling at the same
speed. The actual effectiveness of traffic controls may be less than
theoretical estimates because traffic controls depend largely on voluntary
compliance by drivers and the degree to which regulations are enforced.
4.2.4.2 Costs. The monetary costs of establishing traffic controls
are negligible, but the social costs are significant. One social cost
would be the "cost" of increased travel time related to lower speed
limits. One researcher estimates personal travel time to cost between
$1.68 and $6.57 per hour traveled.6 The Interstate Commerce Commission
(ICC) estimated the value of time losses for commercial vehicle drivers
to be from $7.66 to $17.39 per hour traveled (1977 figures).7 Using
ICC's value, a truck traveling 60 miles a day would require one extra
hour in transit if speed limits were reduced from 30 mph to 20 mph. The
cost of additional travel time in this case would be from $0.13 to $0.29
per mile traveled.
4.2.5 Dust Suppressants
Several types of dust suppressants are commercially available. The
four major types used on unpaved roads are water/wetting agents, calcium
chloride (CaCl2)i lignosulfonate, and petroleum products. A partial list
of dust suppressant manufacturers is shown in Table 4-2. Detailed treatment
instructions are available from manufacturers and should be consulted to
4-5
-------
ensure proper application. The efficiency of any dust suppressant depends
upon (1) soil properties of the road, (2) construction of the road,
(3) method and frequency of suppressant application, (4) type and volume
of vehicular traffic, and (5) local weather conditions.
4.2.5.1 Watering and Wetting Agents. Watering has been used
successfully on unpaved roads only for short-term dust suppression in
circumstances where the roads are confined to a small area, such as
access roads to mines, quarries, or construction projects. Wetting
agents are often mixed with water to extend the effect of roadway watering.
These agents reduce the surface tension of water and promote penetration
to the subsurface. Moisture that evaporates from the soil surface is
replaced by subsurface moisture through capillary action. No adverse
environmental impacts have been reported concerning the use of wetting
agents.
4.2.5.1.1 Application. It requires approximately 1,100 gallons of
water to spray one mile of secondary road at a rate of 0.1 gallon of
water per square yard. The dilution ratio of water to wetting agent
varies from 1,000 to 10,000 gallons of water per gallon of wetting agent
depending upon soil conditions and manufacturer's recommendations.
Compacted soils require less water than looser surfaces.
4.2.5.1.2 Effectiveness/durability. The frequency of water
application depends primarily upon local weather conditions. Suppressing
dust with water alone as a permanent control measure would require an
application every day that is dry and has a temperature above 32°F. No
test data have been reported assessing the relative control efficiencies
of wetting agents. One manufacturer claims that wetting agents can
extend the usefulness of road watering by 33 percent.8
4.2.5.1.3 Costs. As a permanent control measure, road watering is
estimated to cost from $25,600 to $39,000/km per year ($41,000 to $63,000/mi
per year).5 Regional variations in water prices, not considered here,
would be expected to increase the geographical variation in these annual
costs. If wetting agents are used, the cost of wetting roads could be
reduced to $17,000 to $26,000/km per year ($27,000 to $42,000/mi per
year).
4-6
-------
TABLE 4-2. DUST SUPPRESSANT MANUFACTURERS8 9
Company name'
and address
Product trade name0
Chemical type
of product
1. ALCO Chemical Corporation
Philadelphia, Penn.
2. Allied Chemical
Morristown, N.J.
3. American Can Company
Greenwich, Conn.
4. American Corporation
Soil Card
Calcium chloride
Norlig
Curasol
Elastometric polymer
emulsion
Calcium chloride
Calcium
Lignosulfonate
Polymer emulsion
5. American Cynamid Company
Wayne, N.J.
6. American Hoeschst Corporation
Someville, N.J.
7. Arthur C. Trask Company
8. Gordon Chemical Company
Leominister, Mass.
9. Celtite, Inc.
Cleveland, Ohio
10. Crown Zellerbach Company
East Hanover, N.J.
11. Dowel! Division,
Dowel 1 Chemical Company
Tulsa, Okla.
12. Firestone Tire
and Rubber Company
Akron, Ohio
13. Fire Water Company
Los Altos, Calif.
Aerospray R
DCA-70
Curasol
Trastan
Polyco 2607
Polyco 2440
Polybind DLR
Orzan
Latex Ml 45
Latex Ml 66
FRS-275
Crust 500
SC-100
Water synthetic
resin
Organic polymer
Polymer elastics
dispersion
Lignosulfonate
Synthetic copolymer
Copolymer
Polymer
Lignosulfonate
Latex binder
Latex in oil
or water
Polyvinyl acetate
organic polymer
4-7
-------
TABLE 4-2. DUST SUPPRESSANT MANUFACTURERS8 9
(concluded)
Company name3
and address Product trade name
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
Great Salt Lake Minerals and
Chemical Corp.
Little Mountain, Utah
Henly and Company, Inc.
New York, N.Y.
Hercules, Inc.
San Francisco, Calif.
E. F. Houghton Company
Philadelphia, Penn.
Johnson March Corporation
Phillips Petroleum Company
Bartletsville, Okla.
Phillips Petroleum Company
Great Falls, Mont.
Protex Industries, Inc.
Denver, Colo.
Rohm and Haas Company
Philadelphia, Penn.
Sherex Chemicals
Chicago, 111.
Standard Oil Company
3-M Company
St. Paul , Minn.
Witco Chemical
Bakersfield, Calif.
Dustgard
Huls-801
SDX-1
Rozosal
MR
Arcatice
Oust pallative
Various oils
Petroset
Soiltex
Polyacrylic acid
Arosurf AA
•
Oust control
Lanolock XA-2440
Coherex
Semi -Pave
Chemical type
of product
Clacium chloride
Liquid plastic
Resin emulsion
Organic polymer
Wetting agent
Liquid asphalt
emulsion
Residual oil
Residual oil
Rubber emulsion
Lignosulfonate
Polyacrylic acid
Cationic asphalt
emulsion
Petroleum resin
Adhesive binder
Water emulsion of
petroleum resins
Asphalt emulsion
aMaterial names and manufacturers are included for the benefit of the reader
and infer no endorsement or preferential treatment by EPA.
4-8
-------
4.2.5.2 Calcium Chloride (CaC12) Treatment. Calcium chloride has
been used by many county road departments for several decades to mitigate
summer road dust and as a road deicer in winter. An EPA report in 1971
estimated that approximately 330,000 Mg (300,000 tons) of CaCl2 are
spread annually on United States highways.10 Calcium chloride is a
deliquescent material and is able to absorb and retain moisture from the
atmosphere at relative humidities as low as 29 percent.3
4.2.5.2.1 Application. Road surface conditions and traffic volume
dictate the amount, timing, and frequency of calcium chloride application.
Calcium chloride, in either the liquid or flake form, is usually first
applied in the spring and is followed by a second application 3 to 6 weeks
later. According to one vendor, several applications are required to
build up a hard pack surface that will substantially reduce dusting for
prolonged periods. For roads with a traffic volume of 200 to 300 vehicles
per day, three applications within a 15-day period may be required.11
Typically, 0.27 Mg (600 Ib) of the flake form or 3,785 £ (1,000 gal)
of a liquid CaCl2 solution are applied per lane-mile. The dry flake
CaCl2 is distributed onto the surface by means of an automatic spreader.
Liquid CaCl2 is best applied by a truck equipped with a stainless steel
tank and a spray bar controlled by a pump that meters out the solution at
the desired constant spray rate.
4.2.5.2.2 Effectiveness/durability. A recent study by the Nebraska
Health Department found that a single application of a 38 percent CaC12
solution, applied at a rate of 0.9 H/m2 (0.2 gal/yd2) to an unpaved road
with a traffic volume of 200 to 300 vehicles per day, significantly
reduced the total inhalable particulates* for a period of 2 to 3 weeks.11
The reduction of inhalable particles was approximately 40 to 50 percent
after 19 days. Over a 3.5-month period with liquid CaCl2 applied at 3-
to 4-week intervals, total suspended particulate (TSP) levels were reduced
by 81 percent on an unpaved road that carried 200 to 300 vehicles per
day. Similar applications on a road that carried 700 vehicles per day
produced a 66 percent reduction in TSP.11
*Particles smaller than 10 urn in diameter.
4-9
-------
No quantitative test data for the flake form are known; however, the
Virginia Highway Department has reportedly controlled road dust over the
past several years by applying flake CaCl2 two to three times per summer.12
4.2.5.2.3 Costs. The cost of treating a mile of road (20 ft wide)
with CaCl2 is about $375/km ($600/mi) per application, excluding labor.
Annual costs per mile would depend upon the number of applications necessary
in a particular region. The annual cost for calcium chloride treatment
has been estimated to range from $3,000 to $5,000 per year. One county
road department, however, has calculated that the actual net cost of
treating a mile of unpaved road to be less than $100 when reduced
maintenance costs and aggregate savings are considered.13
4.2.5.2.4 Environmental compatibility. Studies have shown that
salts initially penetrate a road to a depth of several inches and then,
with time, rise to the surface by capillary action. Surface salts may be
washed off the road by rainfall. Certain species of trees and shrubs
located adjacent to the road can be adversely affected. Susceptible
species include white pine, hemlock, sugar maple, red maple, and most
ornamentals.14 The chronic and acute toxicity of salt in most sensitive
plants is well documented, but very little is known about the subtle
effects of low levels of salt contamination to "resistant" species after
repeated applications over a long periods of time. Salt disrupts the
osmotic balance within plant cells and interferes with normal photo-
synthesis and respiratory processes. Small amounts of salt absorbed
through the roots will lead to premature coloration of leaves and early
leaf fall the next year. With an acute dose, the plant dies, and the
salts contained therein are recycled to the roadside environment.
The aquatic environment can also be adversely affected by direct
runoff of dissolved salt to waterways. In concentrations greater than
one percent, all fresh water species of bacteria, algae, invertebrates,
fish, and higher plants are placed in immediate jeopardy.14 Small
concentrations of salt appear to act selectively on organisms, favoring
the salt-tolerant species. Salt-induced stratification in small bodies
of fresh water can delay or prevent seasonal mixing and thus contribute
to the deoxygenation of the lower depths. Studies indicate that highway
salts can also accelerate contamination of ponds and lakes by mercury and
4-10
-------
other toxic heavy metals by interfering with the ability of bottom sediments
to bind these toxic substances.14
4.2.5.3 Lignosulfonate. Lignosulfonate is a water soluble liquid
chemical byproduct of the wood pulping industry that can be applied to
road surfaces for dust suppression. The solution drys, and the lignin
fraction serves as a glue that binds fine dust particles. The sulphite
liquor appears to stabilize the road surface by decreasing soil
permeability.15
The soils best suited for lignosulfonate treatment are those where
70 to 100 percent of the particles pass through a 3/4-in. sieve and 50 to
20 percent are silt (i.e., particles that will pass through a 200-mesh
sieve).16
4.2.5.3.1 Application. Best results are obtained when the road is
initially scarified to a depth of 3 in. Usually, a 10 to 25 percent
lignosulfonate solution (in water) is applied at a rate of 4.5 to 9.0 £/m2
(1 to 2 gal/yd2) and mechanically mixed with the soil. Common practice
in road stabilization is to apply 0.5 to 1.0 percent of lignin sulfonate
solids by weight in the soil. Following mixing, the road should be
formed into a modified A-crown with a uniform side slope of about 1/2 in./ft
from the center!ine. Proper crown construction is imperative because
lignosulfonate-treated roads require rapid surface drainage. As a final
step, the road surface is top-dressed with lignosulfonate and compacted
with a roller.16
4.2.5,3.2 Effectiveness. Satisfactory dust control efficiencies
using lignosulfonate have been reported. A mixture of lignosulfonate and
a silicate base compound were applied to a test road in Arizona. Five
months after application, 80 percent dust control was achieved for both
spray-on and mixed-in applications. A lesser degree of dust control was
achieved at 14 months.17
Lignosulfonates have also been tested on mine access roads where
dust problems are often caused by heavy vehicles. It is estimated that
70 percent dust control efficiency over a period of a year can be achieved
with an annual application of 2.4 gal of 12 percent lignosulfonate solution
per square yard of roadway.8
4-11
-------
4.2.5.3.3 Costs. Lignosulfonate treatment has been estimated to
cost from $2,250 to $5,300/km ($3,600 to 8,500/mi).4 8 16 The costs may
be much lower if a local supply of lignosulfonate can be found. Lee
County, Iowa, for example, has solved a disposal problem for a local pulp
manufacturer by hauling away the plant's waste lignosulfonate at no cost
for the material. The county's average annual cost for lignosulfonate
treatment is about $250/km ($400/mi). Costs include aggregate, application,
and hauling.15
4.2.5.3.4 Environmental compatibility. The toxic effects of
lignosulfonates are minimal. Calculations show that a 2 percent ligno-
sulfonate stabilized roadway subjected to a 1-in. rainstorm (while
assuming unrealistically that 100 percent of the lignosulfonate goes into
solution) produces a runoff stream of about 1 percent lignosulfonate by
solid weight.17 This value is well below the maximum 4 percent concen-
tration of lignosulfonate solids allowable for animal ingestion as permitted
by the Food and Drug Administration (CFR 121.234). No studies have been
found that have investigated the effect of lignosulfonates on aquatic
systems.
4.2.5.4 Petroleum Products and Other Chemical Dust Suppressants.
Over 20 petroleum-based dust suppressants are commercially available.
These chemicals are generally classified by their active ingredient
(emulsion, resin, latex, or polymer) and are effective dust suppressants
because they agglomerate soil particles and do not mix with water.
4.2.5.4.1 Application. Petroleum-based dust suppressants can be
either be sprayed on or mixed into the road material. Typical rates for
spray-on application range from 1.0 to 9.0 £/m2 (0.25 to 2.0 gal/yd2).
Mixed-in applications require about twice as much material.8 17
4.2.5.4.2 Effectiveness/durabi1ity. Very good results were reported
in the Arizona Field Tests (1976) using an emulsion and a petroleum resin
to control road dust.17 These chemicals were applied to an unpaved road
that had granitic soil, an average daily traffic of 140 vehicles, and a
surface soil silt content of 28 percent. Four different dust suppressants
were tested with both spray-on and mixed-in types of application. The
percentage of dust controlled by each suppressant 5 months and 14 months
following application is shown in Tables 4-3 and 4-4.
4-12
-------
TABLE 4-3. PERFORMANCE RATINGS AND ROAD CONDITIONS FOR SELECTED ROAD
STABILIZERS MIXED INTO SOIL17
Cost of cneMical
Chemicals'
and its b
applications
$/Ml
Percent4
control
After 5 wmths
Description of
road condition
Percent
control
After M Months
Description of road
after several b lad Ings
9/29/75
Cost
effectiveness
$/ton of dust
emissions
prevented
Redlcote ES2 asphalt Mission:
A catlonic asphalt caulsIon
(7.45X in water) applied at
2.4 gal/yd*.
10.810 94.7 Black, very hard, asphalt-
like surface; little wear;
SMooth; no loos* Mterlal;
no dust behind traffic.
84.4 Black, very hard, asphalt-like
surface; little wear; good riding
quality; tome loose coarse Material;
very little dust behind traffic.
17.0
Dust Bond 100 * F-I2S:
A aixture of lignin sulfate
and other chralcals plus
Formula 125. Applied at
I gal/yd1.
8.440 86.6 Brown, hard surface;
SMooth; little wear; SOBC
loose Material; very light
dust behind traffic.
44.7 Brown; few hard spots; numerous
ruts and potholes; heavy dust
concentration behind traffic.
18.1
Oust control oil Mixture
of petrolem resin and light
hydrocarbon solvent.
Applied at 0.5 gal/yd2.
4.370 80.5 Black, hard at spots; few
ruts and potholes; loose
coarse Material; Moderate
dust behind traffic.
11.5 Dark brown; hard at few spots;
nuewrous ruts and potholes; heavy
dust cloud behind traffic.
13.4
co
Water
600
Natural color; rutted;
several potholes; substan-
tial loose Material; heavy
dust behind traffic.
Natural color; rutted; numerous
potholes; substantial loose Material
heavy dust cloud behind traffic.
aMixing of the chemical stabilizer into the road bed Is accomplished as follows: (I) the surface is first ripped to a depth of 3 inches; (2) the
surface Is sprayed with water; (3) the chemical is sprayed on the surface; (4) the cheMlcal is Mixed into the soil surface with a series of successive
.bladings; and (5) the road surface is compacted by rolling.
Based on state cost figures for cheMlcal stabilizers, adjusted 15 percent upward to reflect current (1976) costs and adjusted another 10 percent to
Include cost of surface preparation and chemical application. Correction to current costs are based on communication with a principal supplier. Costs
include shipping expenses from supplier to Phoenix.
Cost effectiveness is based on the ratio of the cost and the average emissions reduction attained for the period Indicated. This reduction is
estimated by applying the control figures above to the uncontrolled dust emissions corresponding to an unpaved road with ADI of 140. soil silt content
.28 percent, and average vehicle speed of 35 Mph. Roadway dust emissions without control are 712 tons for the 14-Month period.
Control effectiveness is based on dustfall MeasureMents conducted at various distances froM road.
-------
TABLE 4-4. PERFORMANCE RATING AND ROAD CONDITIONS FOR SELECTED ROAD DUST
SUPPRESSANTS, SPRAY-ON APPLICATION17
Chemicals
Cost of chealcal
and Its
application
$/•<
After 5 months
After 14 Months
and several biddings
Percent Description of road
control
condition
Description of road
Percent after several bladlngs
control 9/29/75
Cost
effectiveness
$/ton of dust
emissions
prevented
Oust control oil:
Mixture of petroleum
resin and light hydrocarbon
solvent. Applied at
0.6 gal/yd*.
5.280
95.2 Black, very hard surface;
some potholes near
shoulders; Minimal loose
material; extremely light
dust behind traffic.
54.3 Dark brown, hard surface; scattered
scattered potholes; moderate loose
loose aaterlal but from outside the
side the road; light dust behind
traffic.
9.3
Curasol AE:
A polymer dispersion diluted
in water by 6 to 1. Applied
using 4 passes at 0.25 gal/yd*
each.
8.130
86.9 Dark brown. medium hard
surface; rutted with few
potholes; loose coarse
particles on surface;
moderate dust behind
traffic.
9.4 Brown; several ruts and potholes;
large Mount of loose particles;
very heavy dust traffic.
23.8
I
*>
Aerospray 70:
A polyvlnyl acetate
resin diluted 6 to I with
water. Applied using 4
passes at 0.25 gal/yd1 each.
8,080
82.6 Brown. medium hard surface;
medium wear and ruts; few
potholes; loose coarse
particles on surface;
•oderate dust behind
traffic.
44.3 It. brown; several ruts and pot-
holes; large amount of loose
particles; heavy dust behind
traffic.
18.0
Dust Bond 100 * F-12S:
Mixture of lignin sulfate
and other chemicals.
Applied nondlluted in first
pass at I gal/yd1 then at
l-to-1 dilution plus 2.5X
formula 125 on next pass.
Surface compacted intermit-
tently for several hours
after application.
8.420
88.0 Brown. medium hard surface;
•oderate wear; few pot-
holes; smooth surface;
slippery when wet; mod-
erate dust behind traffic.
17.6 It. brown; few patches of treated
surface; several ruts; large
Mount of loose particles; heavy
dust behind traffic.
22.4
Foramtne 99-194:
A urea-formaldehyde resin
in water solution. Diluted
1.6 to 1 by water application
at I gal/yd2.
10.300
46.6 Natural color; worn and
rutted surface; large
amount of loose parti-
cles; poor riding quality;
heavy dust behind traffic.
8.9
Natural color; similar to untreated
(water) section.
52.2
Water
400
Natural color; soft when
wet; worn and rutted sur-
face; large aawunt of loose
particles; heavy dust cloud
behind traffic.
Natural color; worn; numerous ruts
ruts and potholes; large amount of
loose particles; heavy dust cloud
behind traffic.
Based on 1975 state cost figures for chemical stabilizers, adjusted 15 percent upward to reflect current (1976) costs and another 10 percent to include
cost of surface preparation and applications. Correction for adjustment to current costs Is based on personal communication with a principal supplier.
.Costs include shipping expenses for supplier to Phoenix.
Cost effectiveness Is based on the ratio of the cost and the average emissions reduction attained for the period indicated. This reduction is estimated
by applying the control figures above to the uncontrolled dust emissions corresponding to an unpaved road with AD! of 140, soil silt content of 28X,
and average vehicle speed of 35 mph. The uncontrolled Missions are 254 tons per alle of road for the 5-month period, and 712 for the 14-month period.
Control effectiveness Is based on dust fall measurements conducted at various distances from road.
-------
4.2.5.4.3 Costs. An obvious disadvantage in using petroleum-based
dust suppressants is cost. Cost figures listed in Tables 4-3 and 4-4
range from $3,125 to $6,250/km per year ($5,000 to 10,000/mi per year).
4.2.5.4.4. Environmental compatibility. Certain characteristics of
emulsified asphalt products indicate that these dust suppressants are
environmentally compatible. In general, they are noncorrosive, insoluble
in water, nonevaporative, relatively nontoxic, and do not adversely
affect plant life.
The petroleum-based resins containing hydrocarbon solvents can cause
air pollution when the solvents evaporate. No data have been reported
concerning the environmental compatibility of latex and polymeric products,
4.2.6 Control Techniques Summary
The cost effectiveness of applying gravel, a triple-coat chip seal,
asphalt concrete, and dust control oil to reduce dust emissions from an
unpaved dirt road with an average daily traffic of 100 vehicles was
determined by the Maricopa County (Arizona) Highway Department in 1976.
The study found that the chip seal surface was the most cost effective
alternative ($10.80 per ton of dust controlled) followed by a gravel
surface ($11 per ton of dust controlled), the oiled surface ($19.50 per
ton of dust controlled), and, lastly, the 3-in. asphalt concrete surface
($19.60 per ton of dust controlled). The annual dust control efficiency
was 100 percent for both paved surfaces (neglecting dust entrainment off
the pavement), while the annual dust control efficiencies of the gravel
and oiled surfaces were 50 and 75 percent, respectively.17
A similar study conducted by the Seattle Public Works Department
also showed that the most cost effective method of controlling road dust
is a chip seal if a road's average daily traffic is over 100 vehicles.
Additional benefits from the chip seal surface that were not included in
determining its cost effectiveness were: reduced road maintenance costs,
reduced sewer costs, higher property values, lower vehicle operating
costs, and lower health costs.18
4.3 ADMINISTRATIVE OPTIONS
The administrative options in this section discuss how existing
State and Federal policies and regulations can be modified to eliminate
4-15
-------
chrysotile emissions from unpaved roads and to prevent the surfacing of
unpaved roads with stone containing chrysotile in the future.
4.3.1 Modify Crushed Stone Procurement Practices
A State or Federal agency can discontinue the purchase of crushed
serpentinite for surfacing unpaved public roads. Specifications of
crushed stone for road use can require quarry owners to prove that the
stone contains no chrysotile. New sources of crushed stone may have to
be developed in some areas.
4.3.2 Review Criteria for Road Paving Priorities
Unpaved serpentinite roads can be given high priority for paving.
Selective paving of the dusty, unpaved roads containing chrysotile can
significantly reduce local chrysotile emissions. Particular attention
should be given to residential areas.
4.3.3 Implement Traffic Controls
Lower speed limits can significantly reduce the amount of dust
generated by moving vehicles on unpaved roads if such controls are enforced.
The same is true for limiting the size and weight of commercial vehicles.
4.3.4 Review State Mining Permit Requirements
Petrographic analyses of rock samples may be required of new quarries
planning to operate in areas where serpentinite is likely to occur. A
State may wish to regulate the end uses of serpentinite containing
chrysotile by adding end-use restrictions in the operating permit.
Existing quarries can be brought into compliance with the new requirements
when permits are renewed.
4.3.5 Revise Existing Fugitive Dust Regulations
Most States have general regulations requiring that reasonable
precautions be taken to prevent dust from becoming airborne. In the case
of fugitive dust generated from unpaved roads surfaced with serpentinite,
a maintenance standard or a no-visible emission standard may be vigorously
enforced. Standards may require the implementation of dust control
programs, air monitoring, and/or traffic controls.
4-16
-------
4.4 REFERENCES FOR CHAPTER 4
1. Telecon. Bradshaw, D., North Carolina Department of Transportation,
with Serra, R. , Midwest Research Institute. February 4, 1980. Cost
of constructing crushed stone roads.
2. Telecon. Rutheford, J., Harford County, Maryland, Road Department,
with Serra, R., Midwest Research Institute. January 11, 1980. Cost
of replacing crushed stone on Harford County roads.
3. Setting Priorities for Control of Fugitive Particulate Emissions
From Open Sources. U.S. Environmental Protection Agency. Research
Triangle Park, N.C. Publication No. EPA-600/7-79-186. August 1979.
128 p.
4. Guideline for Development of Control Strategies in Areas With Fugitive
Dust Problems. U.S. Environmental Protection Agency. Research
Triangle Park, N.C. Publication No. EPA-450/2-77-029. October
1977. 158 p.
5. Cowherd, C., Jr., K. Axetell, Jr., C. M. Guenther, and G. Jutze.
Development of Emission Factors for Fugitive Dust Sources. U.S.
Environmental Protection Agency. Research Triangle Park, N.C.
Publication No. EPA-450/3-74-037. June 1974.
6. Winfrey, R. Economic Analysis for Highways. Scranton, Pennsylvania.
International Textbook Co. 1969.
7. Statistical Abstract of the United States: 1977 (98th ed.). U.S.
Bureau of the Census. Washington, D.C. 1977.
8. Bohn, R. , et al. Dust Control for Haul Roads. U.S. Bureau of
Mines. February 1981. 146 p.
9. Jutze, G. and K. Axetell. Investigations of Fugitive Dust. Volume I:
Sources, Emissions, and Control. U.S. Environmental Protection
Agency. Research Triangle Park, N.C. Publication No. EPA-450/3-
74-036a. June 1974. 88 p.
10. Field, R. F. , H. E. Masters, et al. Water Pollution and Associated
Effects From Street Salting. Report 506 Transporration Research
Record. Transportation Research Board, National Academy of Sciences.
pp. 40-46.
11. Walsh, G. L. Control of Fugitive Dust From Unpaved Roads Using
Liquid Calcium Chloride. Final Draft. U.S. Environmental Protection
Agency. Research Triangle Park, N.C. 1980. 48 p.
12. How Virginia Controls Road Dust Annoyance. Rural and Urban Roads.
July 1978. pp. 53-54.
4-17
-------
13. In Winter Snow or Summer Dust, County Relies on Calcium Chloride.
Rural and Urban Roads. November 1978. pp. 56-59.
14. Adams, F. S. Highway Salt: Social and Environmental Concerns.
Report No. 425. Highway Research Record. Highway Research Board,
National Research Council, pp. 6-8.
15. Fox, P. E. and J. M. Hoover. Ammonium Lignosulfonates as Dust
Palliatives and Surface Improvement. Agents for Unpaved Secondary
Roads. Part III of Surface Improvement and Dust Palliation of
Unpaved Secondary Roads and Streets. Engineering Research Institute.
Iowa State University, Ames, Iowa. July 1973. pp. III-l through
III-104.
16. Harmon, J. P. Use of Lignin Sulfonate for Dust Control on Haulage
Roads in Arid Regions. Information Circular 7808. Bureau of Mines.
U.S. Department of the Interior. Washington, D.C. October 1957.
11 p.
17. Sultan, H. A. Soil Erosion and Dust Control of Arizona Highways,
Part IV. Final Report Field Testing Program. Arizona Transportation
and Traffic Institute. Prepared for Arizona Department of
Transportation. November 1976. 110 p.
18. Roberts, J. W., H. A. Watters, C. A. Marigold, and A. T. Rossano.
Cost and Benefits of Road Dust Control in Seattle's Industrial
Valley. Journal of the Air Pollution Control Association.
25:949-952. September 1975.
4-18
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5. CONCLUSIONS AND RECOMMENDATIONS
5.1 CONCLUSIONS
Asbestos is a proven human carcinogen, and no level of exposure is
known below which cancer will not occur. A small number of unpaved
secondary and logging roads surfaced with crushed serpentinite have been
found in a few areas of the United States. In addition, unpaved roads
have been constructed over outcropping of serpentinite in a few areas.
Vehicular traffic over these surfaces results in the release of asbestos
fibers into the atmosphere thereby exposing a small segment of the general
population to low concentrations of a known human carcinogen.
EPA believes that asbestos emissions from unpaved roads and other
dusty sources (such as unpaved parking lots) should be reduced to the
greatest extent practical. The level of asbestos emissions as well as
the most appropriate method to control those emissions varies with location.
EPA has concluded that the specific local, State, or Federal agency
responsible for road maintenance in these areas is in the best position
to assess local conditions and to decide on a proper course of action.
5.2 RECOMMENDATIONS
The Administrator recommends that the responsible levels of government
undertake a course of action in the near future to:
1. Perform an exposure assessment in each area where serpentinite
may be used to surface unpaved roads. This assessment should:
a. Locate all unpaved roads that may be surfaced with
serpentinite;
b. Verify the presence of asbestos in the road material or in
aggregate storage piles by petrographic microscopy; and
c. Determine the number of people residing along these unpaved
roads and the number of people using such roads.
5-1
-------
2. Develop a program to:
a. Eliminate asbestos emissions from unpaved roads surfaced
with serpentinite, where practical, by:
(1) Not using existing supplies of crushed serpentinite for
surfacing unpaved public roads;
(2) Implementing temporary measures (such as using dust
suppressants) to reduce asbestos emissions when dusty conditions are
likely to occur; and
(3) Paving as many unpaved serpentinite roads as resources
will allow. A schedule for paving should prioritize those roads, or
sections of roads, that expose the largest human population to airborne
asbestos.
b. Discourage, through administrative and/or regulatory measures,
the use of crushed serpentinite for maintaining unpaved public roads;
c. Reduce vehicular activity in areas containing natural
outcroppings of serpentinite when dry, dusty conditions are likely to
occur;
(1) Limit potential secondary exposures to family members
from carry-out of asbestos on clothing/equipment; and
d. Inform those persons who may be exposed to asbestos emissions
from unpaved serpentinite roads of the assessment program and inform them
of the various diseases associated with the inhalation of asbestos.
5-2
-------
APPENDIX A. FEDERAL ASBESTOS REGULATIONS
Appendix A is an overview of current Federal regulations governing the
production and use of asbestos and asbestos-containing materials. The
major provisions of asbestos regulations promulgated by the Occupational
Safety and Health Administration (OSHA), Mine Safety and Health
Administration (MSHA), Environmental Protection Agency (EPA), Consumer
Product Safety Commission (CPSC), and the Food and Drug Administration
(FDA) are contained in Tables A-l through A-5.
A-l
-------
TABLE A-l. OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION ASBESTOS REGULATIONS
Citation
Major provisions
36 FR 10456
(5/29/71)
36 FR 23207
(12/7/71)
ro
37 FR 11318
(6/7/72)
Air contaminant (gases, vapors, fumes, dust, and mists) regulations.
Exposure by inhalation, ingestion, skin absorption, or contact to any material
or substance at concentrations above those specified for the given material or
substance shall be avoided, or protective equipment shall be provided and used.
The concentration specified for asbestos is 12 fibers greater than 5 urn in
length per milliliter of air, as determined by the membrane filter method at
430 phase contrast magnification or 2 million particles per cubic foot of air,
based on impinger samples counted by light-field techniques.
Emergency standard for exposure to asbestos dust.
The 8-hour TWA (time-weighted average) airborne concentration of asbestos dust
to which employees are exposed shall not exceed five fibers greater than 5 urn
in length per milliliter of air, as determined by the membrane filter method at
400-450 magnification phase contrast illumination. Concentrations above
5 fibers per milliliter, but not to exceed 10 fibers per milliliter, may be
permitted up to a total of 15 minutes in an hour for up to 5 hours in an 8-hour
day.
Standards for exposure to asbestos dust.
1. Standard effective July 7, 1972. The 8-hour TWA airborne concentra-
tions of asbestos fibers to which any employee may be exposed shall not exceed
five fibers longer than 5 urn per cubic centimeter of air as determined by the
membrane filter method at 400-450 magnification with phase contrast
illumination.
2. Standard effective July 1, 1976. The 8-hour TWA airborne concen-
trations of asbestos fibers to which any employee may be exposed shall not
exceed two fibers longer than 5 urn per cubic centimeter of air.
-------
TABLE A-l. OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION ASBESTOS REGULATIONS
(concluded)
Citation
Major provisions
37 FR 11318
(6/7/72)
(continued)
41 FR 11504
(3/19/76)
3. Ceiling Concentration. No employee shall be exposed at any time to
airborne concentrations of asbestos fibers in excess of 10 fibers longer than
5 pro per cubic centimeter of air.
Includes methods of compliance, warning signs, monitoring, medical examina-
tions, and recordkeeping.
Extends the recordkeeping requirement for exposure monitoring from 3 years
to 20 years.
CO
-------
TABLE A-2. MINE SAFETY AND HEALTH ADMINISTRATION ASBESTOS REGULATIONS
Citation
Major provisions
39 FR 24316
(7/1/74)
41 FR 10223
(3/10/76)
Health and safety standards for asbestos.
The 8-hour TWA airborne concentration of asbestos dust to which employees are
exposed shall not exceed five fibers greater than 5 urn in length per milliliter,
as determined by the membrane filter method at 400-450 magnification phase
contrast illumination. No employee shall be exposed at any time to airborne
concentrations of asbestos fibers in excess of 10 fibers longer than 5 urn per
milliliter of air, as determined by the membrane filter method over a minimum
sampling time of 15 minutes.
The term "asbestos" as used herein is limited to the following minerals:
chrysotile, amosite, crocidolite, anthophyllite asbestos, tremolite asbestos,
and actinolite asbestos.
The 8-hour TWA airborne concentration of asbestos dust to which miners
are exposed shall not exceed two fibers per cubic centimeter of air. Exposure
to a concentration greater than 2 fibers per cubic centimeter of air, but not
to exceed 10 fibers per cubic centimeter of air, may be permitted for a total of
1 hour each 8-hour day. The term asbestos does not include nonfibrous or
nonasbestiform minerals.
The determination of fiber concentration shall be made by counting all fibers
longer than 5 urn in length and with a length-to-width ratio of at least 3:1 in
at least 20 randomly selected fields using phase contrast microscopy at
400-450 magnification.
-------
TABLE A-3. ENVIRONMENTAL PROTECTION AGENCY ASBESTOS REGULATIONS
Citation
Major provisions
36 FR 5931
(3/31/71)
Asbestos listed as a potential hazardous air pollutant.
38 FR 8820
(4/6/73)
i
in
39 FR 7526
(2/26/74)
Promulgation of national emission standards for asbestos.
Prohibits the surfacing of all roadways except those on ore deposits with
asbestos tailings.
Prohibits visible emissions from any part of the asbestos mill, but does
not apply to dumps of asbestos tailings or open storage of asbestos ores.
Prohibits visible emissions from the nine manufacturing operations which are
major sources of asbestos; the standard does not cover fabrication operations.
Prohibits visible emissions which contain asbestos from a number of sources
and provides the option of using specified air-cleaning methods.
Specifies certain work practices which must be followed when demolishing
certain buildings or structures which contain friable asbestos material.
Limits the asbestos content to no more than 1 percent for spray-on materials
used to insulate or fireproof buildings, structures, pipes, and conduits.
Establishes final effluent limitations guidelines for existing sources and
standards of performance and pretreatment standards for new sources within the
asbestos-cement pipe, asbestos-cement sheet, asbestos paper (starch binder),
asbestos paper (elastometric binder), asbestos millboard, asbestos roofing
products, and asbestos floor tile subcategories of the asbestos manufacturing
category of point sources.
-------
TABLE A-3. ENVIRONMENTAL PROTECTION AGENCY ASBESTOS REGULATIONS
(continued)
Citation
Major provisions
39 FR 15396
(5/3/74)
40 FR 1874
(1/9/75)
Clarification of regulations promulgated 4/6/73 (38 FR 8820). Definitions
are presented for "alternative method," "commercial asbestos," "asbestos mill"
or "manufacturing" operation, and "demolition."
Established final effluent limitation and guidelines for several additional
subcategories within the asbestos manufacturing category.
O>
40 FR 48292
(10/14/75)
42 FR 12127
(3/2/77)
Amendment of the asbestos standard stating that there shall be no visible
emissions to the outside air: (1) during the collection, processing,
packaging, transporting, or deposition of any asbestos-containing waste
material which is generated by manufacturing, fabricating, demolition,
renovation, spraying, and milling operations; (2) from operations involving the
fabrication of cement building products, friction products, and cement or
silicate board if they use commercial asbestos; (3) from the manufacture of
shotgun shells and asphalt concrete if they use commercial asbestos.
Regulation covers the demolition and renovation of structures which contain
any pipe, duct, boiler, tank, reactor, turbine, furnace, or structural member
that is insulated or fireproofed with friable asbestos material.
Molded insulating materials which are friable and wet-applied insulating
materials which are friable after drying, shall contain no commercial asbestos
Amendment of the asbestos standard. Clarifying the demolition and renovation
provisions of the asbestos standard.
42 FR 64572
(12/23/77)
Authorization to identify and regulate any unreasonable risk to health or
the environment presented by naturally occurring chemical substances. Asbestos
is included as a naturally occurring chemical substance subject to inventory
reporting regulations.
-------
TABLE A-3. ENVIRONMENTAL PROTECTION AGENCY ASBESTOS REGULATIONS
(concluded)
Citation
Major provisions
43 FR 26372
(6/19/78)
Amendment of the asbestos standard. Extending coverage of the demolition and
renovation provisions to all friable asbestos materials and extends coverage
of the asbestos spraying provisions to all materials which contain more than
1 percent asbestos. Materials in which the asbestos fibers are encapsulated
and which are not friable after drying are exempt from the spraying provisions.
-------
TABLE A-4. CONSUMER PRODUCT SAFETY COMMISSION ASBESTOS REGULATIONS
Citation
42FR 63354
(12/15/77)
Major provisions
Banned consumer patching compounds and artificial emberizing materials (used
in fireplaces to simulate live embers and ash) that contain respirable free-
form asbestos.
00
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TABLE A-5. FOOD AND DRUG ADMINISTRATION ASBESTOS REGULATIONS
Citation Major provisions
37 PR 14872 Banned asbestos-containing garments, for general use in households, from inter-
(7/26/72) state commerce.
40 FR 11865 Established good manufacturing practices to limit asbestiform particles in
(3/14/75) drugs for parenteral injection. Filters used in manufacturing, processing or
packaging of drugs shall not release fibers into such products.
41 FR 3286 Revoked regulations that permitted the electrolytic diaphragm process used
(1/22/76) in salt production because the process does not remove asbestos impurities from
salt as well as conventional methods do.
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APPENDIX B. SAMPLING AND ANALYSIS OF AIRBORNE CHRYSOTILE ASBESTOS
CONCENTRATIONS AT FIVE TEST SITES
B.I TEST PROGRAM DESCRIPTION
A test program was undertaken by EPA in 1979 to assess airborne
chrysotile asbestos concentrations downwind from unpaved roads surfaced
with serpentinite, near quarries where serpentinite is mined, and at a
recreational area located in a large outcropping of serpentinite.
Upwind and downwind samples were collected near two unpaved roads in
Harford County, Maryland to determine the chrysotile concentration of the
airborne dust generated by road traffic. The number and speed of automobile
passes were monitored during testing. All sampling runs were conducted
during a 2-hour time period when the wind direction was predominently
perpendicular to the road. Wind speed, wind direction, temperature,
relative humidity, and percent cloud cover were recorded at the beginning,
the midpoint, and the end of each sampling run. During testing, wind
speed and wind direction showed typical periods of calm and gusty conditions
about the prevailing wind direction. Sampling was also conducted near an
unpaved road in Tuolumne County, California; however, sampling was limited
because of fluctuating wind conditions.
Air monitoring was conducted near the boundary of two serpentinite
quarries to determine the impact of quarry emissions on ambient air.
Sampling was conducted over 4 to 8-hour time periods on several days.
Activity within one of the quarries was noted during sampling.
Air monitoring was conducted of a campsite in the Clear Creek
Recreational Area, in central California, to determine ambient asbestos
concentrations in the area. Meteorological conditions and off-road vehicle
activity were noted during the 5-hour sampling period. Airborne particulate
samples were also collected at the edge of the unpaved road leading to
B-l
-------
the campsite and in a vehicle traveling behind another vehicle along the
roadway. These sampling runs were each approximately 15 minutes in
duration, and the data collected represents peak asbestos concentrations
near the roadway when dusty conditions exist.
Both membrane samplers and high-volume samplers were used for
collection of airborne particulate samples at all sites except for the
recreational area where personnel samplers were used. Membrane samplers
collected airborne particulate matter on polycarbonate filters at an air
flow rate of 90 liters per minute (1/min). The flow rate through the
membrane samplers was calibrated at the beginning of each sampling run
with an EPA Audit Orifice which was referenced against a Roots Meter. A
quality assurance audit was conducted by an EPA auditor using an independent
Roots Meter which had been referenced against National Bureau of Standard
reference standards. The pressure drop across the orifice (while cali-
brating) was measured and compared with the calibration data sheets to
determine sampler flow rate at standard conditions. Filters from the
membrane samplers were removed after each sampling run and stored for
later analysis by electron microscopy (EM) for chrysotile concentration.
The high-volume samplers were used to collect total suspended parti-
culate matter (TSP) on glass fiber filters at a flow rate of approximately
1,100 2/min. These samplers were calibrated at the beginning of the
study using a calibrated EPA Audit Orifice. Each sampler was equipped
with an electronic flow controller and a Dickson Recorder. Actual flow
rates were determined using the recorded data and the calibration curves.
Personnel samplers were calibrated before and after each sampling
run using a Hastings Mini-Flo calibrator. Three to five flow measurements
were taken for each sampler, averaged, then standardized to determine
sample volume per minute.
A sample of the road surface material was collected immediately
prior to each sampling run at the road sites. Silt and moisture content
were determined for these surface material samples. Each sample was
comprised of all the loose material above the road hardpan in a
2.5 m x 12 cm strip across one lane of the road. Six of the roadway
samples were later analyzed for asbestos concentration (percent weight)
B-2
-------
as were one soil sample from the recreation area and a sample of crushed
serpentinite produced by one of the two quarries.
B.2 SAMPLE FILTER HANDLING
B.2.1 Sampler Loading
All membrane samplers were equipped with detachable sampler heads.
Sampler heads were loaded with a polycarbonate filter and two backup
filters before each sampling run. A 102-mm glass fiber filter was placed
on the wire mesh support of the sampler head, followed by a 1.0-mm thick
Teflon 0-ring, and a 102-mm, 5-um pore size cellulose ester filter (with
the uniform pattern side facing down). A 102-mm, 0.4-um pore size polycar-
bonate filter was then placed on top of the backup filters with the shiny
side facing up. A 2.0-mm thick Teflon 0-ring was placed on top of the
polycarbonate filter and the filter assembly was secured to the sampler
head by three bolts. All loaded membrane samplers were operated
simultaneously during each sampling run. Elasped time meters were used
to record sampling times.
High volume samplers were loaded with preweighed glass fiber filters
before each day's sampling runs.
Personnel filter cassettes (a plastic cyclinder with a capped hole
in the top and bottom) were loaded by placing a 37-mm cellulose ester
support pad in the bottom of the cassette followed by a 37-mm, 5.0-um
pore size cellulose ester filter and a 37-mm, 0.4-um pore size polycarbonate
filter (shiny side up). At the time of sampling, the cassette was uncapped
and connected to the inlet of the personnel sampler with a piece of tygon
tubing and a stainless steel male adapter. After a sampling run, the
cassette was capped, labeled, and stored in an upright position until
carbon coating was applied.
B.2.2 Sampler Unloading
Membrane sampler heads were carried in an upright position to a
nearby vehicle that served as a field laboratory for unloading. Forceps
were used to transfer the polycarbonate filter from the sampler head to a
numbered petri dish. The filter (sample side up) was secured to the
bottom of the petri dish by attaching cellophane tape to the unexposed
edges of the filter. The petri dishes were then sealed and stored upright
B-3
-------
for subsequent transportation to the nearest facility, either the University
of California at Berkley or the U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, where carbon coating was applied.
Glass fiber filters were removed from high-volume air samplers after
each day's sampling runs. The filters were covered with a sheet of
paper, folded lengthwise, and inserted in a labeled envelope. The envelopes
were transported to EPA, Research Triangle Park, where they were reweighed
and TSP concentrations were determined.
B.2.3 Carbon Coating of Polycarbonate Filters
Polycarbonate filters were carbon-coated after sampling to prevent
rearrangement or loss of asbestos fibers. The coating procedure secures
a vapor-deposited layer of carbon onto the filter surface, thus fixing
the position of any fibers that are present.
Due to the limited size of the vacuum evaporators, only a portion of
each polycarbonate filter was carbon-coated. The 102-mm size filters
were carefully sectioned with a scapel and one section was transferred to
a smaller petri dish (sample side up). Cellophane tape was used to
secure the filter to the bottom of the dish. The 37-mm personnel filters
were sliced into two sections while still in the personnel cassette. One
section was transferred to a small petri dish and secured with tape. The
petri dishes were sealed and sample identification was placed on both the
top and bottom of each dish. If a filter section wrinkled or buckled
during the cutting or transferring procedure, the filter section was
voided and a second section of the filter was prepared.
Three samples, in uncovered petri dish bottoms, were placed on the
turntable of the vacuum evaporator. A pure carbon rod was placed in a
spring-loaded holder and served as the vaporizing electrode. The rod
rested against a flat carbon-faced surface that served as the second
electrode to complete the circuit. The bell jar was evacuated until
5xlO-s torr was reached, and then the electrode current was quickly
increased to 24 ampheres and maintained for 5 seconds. The current
vaporized the carbon rod and produced a layer of carbon film over the
sampling filters. The bell jar was returned to atmospheric pressure, and
the samples were removed and the dish covers replaced.
B-4
-------
B.2.4 Filter Shipment
The petri dishes containing the carbon-coated polycarbonate filters
were relabeled with a three-digit code number. One hundred and forty-six
samples were mailed to Denver Research Institute (DRI), and 70 samples
were mailed to Ontario Research Foundation (ORF) for TEM analysis.
Crushed stone samples collected at the various sites were placed in
sealed plastic bags, identified by a code number and sent to the University
of Minnesota at Duluth (UMD) for TEM analysis.
B.3 SAMPLE ANALYSIS
All samples were prepared and analyzed for chrysotile asbestos
following EPA Report 600/2-77-178 with minor modifications to the
procedures.1 Due to unanticipated delays, DRI was able to process only
80 of 143 airborne particulate samples.2 ORF and UMD processed all
samples received. In addition, both ORF and UMD reported chrysotile and
amphibole fiber concentrations. (DRI did not have the analytical capability
to positively identify amphibole fibers). Amphibole concentrations are
not included in this test report but can be found in ORF's and UMD's
final reports.3 4
B.3.1 Road Surface Material Samples
UMD determined the mineral fiber content of eight crushed stone.
samples. The results are presented in Table B-l. The basic procedure
used to analyze the samples was the procedure used for analyzing airborne
particulate samples. Prior to TEM analysis, a representative portion of
each sample was reduced to a powder by grinding and then was ultrasonified
in a 0.001 percent aerosol OT* solution for several minutes. The sample
volume was adjusted to 1 £ and a small measured volume of sample was
pipetted and filtered through a 0.1-um polycarbonate filter. Following
filtration, the polycarbonate filter was dried and carbon-coated. TEM
analysis was then conducted.
B.3.2 Airborne Particulate Samples
DRI and ORF determined chrysotile fiber concentrations of 150 airborne
particulate samples (including three blank filters). The reproducibility
*Dioctyl sodium sulfosuccinate.
B-5
-------
and precision of the analytical methodology for determining ambient
concentrations of asbestos were evaluated by having a number of split and
colocated samples analyzed by both laboratories. Both laboratories
reported that "free" asbestiform fibers and "asbestiform fibers associated
with other deposits" were present on many of the prepared sample grids.
In some cases, the "other deposits" appeared to be composed of mats,
sheaves, and/or bundles. Inspection by scanning electron microscopy
showed that significant numbers of fibers were present on the sample
grids which were not visible in the routine TEM image.
Chrysotile fibers were positively identified by morphology and by
selected area electron diffraction (SAED). Chrysotile fibers have a
unique tubular morphology that can be easily distinguished from other
types of asbestos. Nearly all the Chrysotile fibers observed were shorter
than 5.0 urn in length and less than 1.0 urn in diameter. Most of the
asbestiform fibers associated with "other deposits" could not be positively
identified by SAED because a suitable SAED pattern could not be obtained.
In some cases, fibers were too thick to obtain a SAED pattern or too
close to other mineral particles to obtain an unambiguous pattern. DRI
identified Chrysotile fibers associated with such deposits by morphology.
ORF observed many asbestiform fibers with slightly altered morphology and
classified them as "other asbestiform fibers with tubular morphology
resembling Chrysotile." ORF strongly suspected that these fibers were
Chrysotile. ORF did not observe any fibers similar to Chrysotile in
morphology but which could be shown to be nonasbestos.
The Chrysotile fiber concentrations reported in this study are the
sum of free Chrysotile fiber concentrations, concentrations of Chrysotile
fibers associated with other deposits, and concentrations of other asbesti-
form fibers that were strongly suspected of being Chrysotile. Only those
particles with at least a 3:1 length-to-width ratio were counted as
fibers. If one end of a fiber was partially obscured, the length reported
was twice the visible length (provided the visible portion had an aspect
ratio of 3 or greater).
The methodology used by the participating laboratories allows
characterization of respirable fiber concentrations as they occur in the
environment; it does not allow for estimation of the potential release of
B-6
-------
many fibers from a single bundle or sheave. In general, the crystalline
deposits observed had mean diameters that ranged in size from submicrometer
up to 12.5 urn. In order to assess the potential for release of respirable
airborne fibers from these deposits, redispersal of the loosely bound
fiber aggregates was recommended by the participating laboratories.
B.3.3 Total Suspended Particulate
TSP was collected by high-volume samplers on preweighed filters at
the unpaved road sites whenever three 2-hour sampling runs were conducted
on a single day. Each high volume sampler was operated only during the
6 hours of sampling. High volume samplers were not operated on days when
fewer than three runs were conducted because TSP loading on the filters
would be insufficient for mass determination. TSP mass concentrations
were determined by dividing the difference between the final filter
weight and the preweight of the filter by the volume of air pulled through
the sampler.
B.4 SITE-SPECIFIC TESTS: DESCRIPTION AND RESULTS
Air monitoring for asbestos was conducted between September and
December 1979 at the following six sites:
1. Holy Cross Road, Harford County, Maryland
2. McNabb Road, Harford County, Maryland
3. Clear Creek Recreational Area, San Benito County, California
4. Cedar Hills Quarry, Lancaster County, Pennsylvania
5. Woods Creek Quarry, Tuolumne County, California
6. Duffy Road, Tuolumne County, California
B.4.1 Holy Cross Road
Holy Cross Road is an unpaved road in rural Harford County, Maryland.
The road is level and surfaced with crushed serpentinite produced by
Cedar Hills Quarry. Air sampling was conducted at this site to assess
the distribution of airborne asbestos concentrations downwind of a road
surfaced with serpentinite. Meteorological data, traffic data, and road
surface characteristics were monitored while airborne particulate matter
was collected. A diagram of the Holy Cross Road site is shown in
Figure B-1.
B-7
-------
UPWIND SAMPLERS LOCATED
3 m ABOVE GROUND SURFACE
WIND
DIRECTION
T
25 m
CORN FIELD
W
CORN FIELD
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HOLY CROSS ROAD
CORN FIELD
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DIRT TRAIL
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M MEMBRANE SAMPLER
H HI-VOL SAMPLER
T TRAFFIC COUNTER
Figure B-l. Site 1—Holy Cross Road, Harford County, Maryland.
-------
Two membrane samplers and a high-volume air sampler were placed in a
row 25 m north of the road. These three samplers measured background
(i.e., upwind) particulate concentrations since sampling was conducted
when the prevailing wind direction was from the north. These samplers
rested on a platform 3 m above ground level with the sampling inlet
approximately 3.5 m above ground. (A platform was used because the site
was located in a cornfield.) On the south side of the road (i.e.,
downwind), three rows of samplers were placed parallel to the road at
distances of 15 m, 31 m, and 61 m from the road. Each row included a
high-volume sampler and either two or three membrane samplers. Downwind
samplers were situated at ground level with the sampling inlets 1.5m
above ground level.
Three road surface samples collected on different dates were analyzed
for asbestos by electron microscopy. One of the samples was of stone
that had been "in place" on the road for several months and was found to
contain 0.14 percent chrysotile by weight. Two surface samples were
"fresh" stone that was placed on Holy Cross Road during the sampling
program on September 26, 1979, and both were found to contain 0.03 percent
chrysotile by weight. See Table B-l.
Airborne chrysotile fiber concentrations determined during seven
tests at Holy Cross Road are presented in Tables B-2 through B-8. Average
(geometric) chrysotile fiber concentrations are plotted versus receptor
distance in Figure B-2. (The geometric average rather than the arithmetic
average was calculated for split and colocated samples because airborne
concentrations of mineral particulates are generally log normally
distributed.) Figure B-2 shows that average chrysotile concentrations
measured at the furthest downwind distance are higher than the average
upwind concentrations for six of the seven tests. During all seven runs,
chrysotile fiber concentrations decreased with receptor distance downwind
from the road. Run 027, which showed higher upwind concentration, had
only one upwind sample analyzed, and thus this value could not be verified.
On Runs 032 and 034, the 61-meter downwind sampler experienced mechanical
trouble, and the samples had to be voided. For the other five runs,
average chrysotile fiber concentrations of the 61 m station, ranged from
B-9
-------
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0.14 to 1.1 fibers/ml, with the typical value being approximately
0.6 fibers/ml.
TSP data from two days of testing at Holy Cross Road are shown in
Figure B-3. The data similiarly show higher dust concentrations downwind
of the road than upwind of the road. Downwind concentrations decreased
with distance from the road.
Average airborne chrysotile fiber concentration plotted versus TSP
for the two different concentrations of chrysotile in the road stone are
shown in Figure B-4. During the series of runs on September 19, 1979
(Runs 016, 017, 018), the chrysotile content of the road stone was
0.14 percent. On September 26, 1979, new stone was added to the road
surface. For the series of runs conducted on October 18, 1979,
(Runs 032, 034, 035), the chrysotile content of the road stone was
0.03 percent. No value was plotted for the monitoring station 61 m
downwind on that date because the station was not functional during
Runs 034 and 035. It can be inferred from this plot that crushed roadstone
containing increasing amounts of chrysotile will result in increasing
airborne concentrations of chrysotile. It can also be inferred that
chrysotile emissions for unpaved roads surfaced with serpentinite can be
limited by reducing total TSP emissions.
B.4.2 McNabb Road
McNabb Road is an unpaved road located approximately 10 miles east
of the Holy Cross Road site. The road is also surfaced with crushed
serpentinite produced by the Cedar Hills Quarry. Crushed serpentinite
had not been added to the road's surface for at least one year prior to
sampling. Upwind/downwind sampling was conducted at this site to assess
chrysotile emissions from an older crushed serpentinite surface.
The arrangement of samplers used at McNabb Road is shown in Figure B-5.
Three membrane samplers and a high volume air sampler was placed in a row
14 m northeast of the road. These samplers were below road level because
of sloping terrain. A similar complement of samplers was placed in a row
25 m southwest of the road at ground level, with the inlets located at
1.5 m above grade. The sampling protocol followed at the McNabb Road
site was the same as at other sites. Sampling was conducted when the
prevailing wind direction was perpendicular to the road. Wind speed and
B-ll
-------
HOLY CROSS ROAD
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DISTANCE FROM ROAD (METERS)
61
Runs 016, 017, and 018 were conducted on 9/19/79
(62 vehicle passes during 6 hours of sampling)
(wind sneed varied from 6 to 9 m/s)
Runs 032, 034, and 035 were conducted on 10/18/79
(80 vehicle passes during 6 hours of sampling)
(wind speed varied from 1 to 4 m/s)
Figure B-3. Total suspended particulate concentrations
for two days of sampling at Holy Cross Road.
B-12
-------
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TOTAL SUSPENDED PARTICULATE (TSP) (ug/m3)
500
600
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Percent chrysotile by weight in roadstone.
Average (geometric) chrysotile concentration for Runs 016, 017, 013
(total of 62 vehicle passes):
1 * At 15 m downwind (an average of 7 values)
2 = At 30 m downwind (an average of 14 values)
3 = At 61 m downwind (an average of 8 values)
Average (geometric) chrysotile concentration for Runs 032, 034, 035
(total of 80 vehicle passes):
1 s At 15 m downwind (an average of 6 values)
2 « At 31 m downwind (an average of 9 values)
Figure B-4. Average (geometric) chrysotile fiber concentrations
versus TSP concentrations for two sets of runs with 2
different chrysotile (by weight) concentrations in the roadstone.
B-13
-------
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Figure B-5. Site 2—McNabb Road, Harford County, Maryland.
-------
direction data represent the average of three hourly readings. The
volume of traffic generated along the road during each 2-hour sampling
period ranged from 15 to 30 vehicles.
For the seven tests conducted at McNabb Road, downwind chrysotile
fiber concentrations ranged from 0.55 to 1.98 fibers/ml while upwind
samples had chrysotile fiber concentrations ranging from 0.0 to
1.42 fibers/ml. These results are shown in Tables B-8 through B-15. The
upwind and downwind average (geometric) chrysotile fiber concentrations
for all seven runs are shown in Figure B-6. The data show that for six of
the seven runs, downwind chrysotile fiber concentrations were significantly
greater than upwind concentrations. The upwind value for Run 013 (which
exceeded the downwind average) represents a single analysis and thus
could not be compared with another sample.
McNabb Road had only one upwind sampler location and one downwind
sampler location; thus, it is not possible to plot chrysotile concentration
versus distance from road. No statistical relationship was found for
chrysotile fiber concentration (geometric average) versus number of
vehicle passes. The percentage of chrysotile mass in the road surface
stone from McNabb Road was determined to be approximately 0.06 percent
(Table B-8).
B.4.3 Clear Creek Recreation Area
The Clear Creek Recreation Area consists of 43,000 acres of Bureau
of Land Management (BLM) administrated public lands located approximately
115 miles southeast of San Francisco, California. The main access route
into the mountainous area is an unpaved canyon road that parallels Clear
Creek and passes several campsites.
The area is visited by over 40,000 people annually, 85 percent of
whom are operators of off-road vehicles. The dust generated in the area
by vehicles and natural forces has raised health concerns because the
area is located in a massive outcropping of serpentinite. Air sampling
was conducted at a campground to determine ambient chrysotile concentrations
in the area. The campsite was located approximately 200 ft from Clear
Creek Road, 2 to 3 miles from the entrance to the area. Two personnel
samplers, equipped with polycarbonate filters, were placed 300 ft apart.
Samplers were placed 1.5 m above ground level. The sampling run lasted
B-15
-------
McNABB ROAD
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DISTANCE FROM ROAD (METERS)
Figure B-6. Upwind and downwind chrysotile fiber concentrations
(geometric average) for seven sampling runs at McNabb Road.
B-16
-------
approximately 5 hours, during which approximately 25 off-road vehicles
were observed in the area. Meteorological conditions were measured
hourly during sampling. Winds were moderate and soil conditions were
dry. Ambient chrysotile fiber concentrations ranged from 1.26 to
6.39 fibers/ml. These results are shown in Table B-16.
Several airborne particule samples were collected in a vehicle
closely following another vehicle traveling along Clear Creek Road. A
personnel sampler was also placed at the edge of the road, 1.5m above
grade. Approximately 25 vehicle passes were made by the stationary
sampler during each 15-minute sampling run. Chrysotile concentrations
determined for the six samples collected in the vehicle ranged from 383
to 972 fibers/ml (geometric average = 549 fibers/ml). Eleven samples
collected at the edge of the road ranged from 0.95 to 206 fibers/ml
(geometric average = 11.15 f/ml).2 3 Total volume of air sampled during
each run was very small (approximately 0.01 m3) and thus, the results
should be viewed as possible peak exposure levels near the road, not
ambient concentration values.
B.4.4 Cedar Hills Quarry
Air sampling was conducted at a site downwind from the Cedar Hills
Quarry to determine if quarrying of serpentinite results in significant
emissions of chrysotile asbestos to the ambient air. Two membrane samplers
and a high-volume air sampler were placed approximately one-quarter mile
south of the quarry property boundary. A line of tall trees, a steep
creek bank, and a creek were between the samplers and the quarry. Sampling
was conducted on three days when the quarry was operating and the prevailing
wind direction was north. Each sampling run was conducted for approximately
8 hours. Quarry activity was not monitored during sampling, and the
chrysotile content of the stone processed on those days is not known.
Atmospheric transport of particulate was partially obscured from the
quarry by a line of trees.
Eight airborne particulate samples were found to contain chrysotile
fiber concentrations ranging from 0.01 to 0.35 fiber/ml (geometric
average = 0.13 fiber/ml). These results are shown on Table B-17.
B-17
-------
B.4.5 Woods Creek Quarry
Air sampling was conducted downwind of Woods Creek Quarry to determine
if quarrying of serpentinite results in significant emissions of chrysotile
asbestos to the ambient air. Six membrane samplers and three high-volume
samplers were placed in a row approximately 200 m downwind from the
quarry's rock crusher. Each sampling run lasted for approximately 4 hours.
Meteorological data were recorded hourly, and quarry activity was noted
throughout each samplng run. Emissions from the crushing operation
generally were well controlled by wet suppression. Visible emissions
occurred at the beginning of a "crushing run" and as a result of vehicular
activity around the quarry.
Ten airborne particulate samples collected during 2 days were
determined to have chrysotile fiber concentrations ranging from 0.03 to
0.11 fiber/ml (geometric average = 0.05 fiber/ml). These results are
shown in Table B-18. Analysis of a single crushed stone sample collected
on one of the 2 days from the quarry's rock crusher was determined to
contain approximately 0.01 percent chrysotile (by weight).
B.4.6 Duffy Road
Duffy Road is an inclined, unpaved road in Tuolumne County, California,
that runs north and south. The road is surfaced with crushed serpentinite
produced by the Woods Creek Quarry. Air sampling was conducted at this
site to assess airborne asbestos concentrations generated by vehicular
traffic. A membrane sampler and a personnel sampler (with sampling
inlets about 1.5 m above the ground) were placed 4 m to the east of the
road and 10 m to the west of the road. The wind direction during sampling
fluctuated from Southwest to South, thus a true background (i.e., upwind)
concentration was not obtained. Fifteen to 30 vehicles passed were made
during each sampling run. The chrysotile fiber content of three samples
collected west of the road (generally upwind) ranged from 0.24 to
3.90 fibers/ml (geometric average = 0.79 fiber/ml). The chrysotile fiber
content of the six samples collected east of the road (generally downwind)
ranged from 0.17 to 6.33 fibers/ml (geometric average =1.20 fibers/ml).2 3
B-18
-------
B.5 LABORATORY COMPARISONS
Inter- and intralaboratory comparisons were computed for the sums of
all possible chrysotile fibers in the airborne particulate samples reported
in Tables B-2 through B-18. Samples from the Duffy Road site and Clear
Creek Road were not used in calculating these values because of fluctuating
wind conditions and because of extremely low air sample volumes. Percent
differences were used to compute laboratory comparisons. The coefficient
of variation for each case was estimated using the estimated standard
deviation of the percent differences divided by the square root of 2.
The estimate of the coefficient of variation was then multiplied by 2 to
produce the length of the interval (expressed as a percent of the true
value) within which two test results should fall 90 percent of the time.
The coefficient of variation for inter- and intralaboratory analysis of
both split and colocated samples ranged from 34 to 72 percent. The
interval length ranged from 68 to 144 percent.5 These results are shown
in Table B-19.
B.6 QUALITY ASSURANCE
All samples analyzed by the participating laboratories were identified
with a three-digit code number. Each laboratory conducted inhouse
procedures to safeguard against contamination of the samples. In addition,
two blank polycarbonate filters were included in the samples analyzed by
ORF. The chrysotile fiber concentrations reported for these two samples
were 0.02 and 0.07 fibers/ml. One blank polycarbonate filter was included
in the samples analyzed by DRI. The chrysotile filter concentration for
this sample was reported to be 0.15 fiber/ml.
B.7 CONCLUSIONS
1. Statistical evaluation of the results indicate that ambient
chrysotile fiber concentrations can be measured with an acceptable degree
of precision. The coefficient of variation for intra- and inter!aboratory
analysis of split and colocated samples ranged from 34 percent to 72 percent
(see Table B-19).
2. Analyses indicate that airborne chrysotile fiber concentrations
downwind of unpaved roads surfaced with crushed serpentinite, containing
trace amounts of chrysotile and subject to light-to-moderate traffic, are
B-19
-------
significantly higher than concentrations upwind of those roads. The
geometric mean for 16 upwind samples from the unpaved roads in Harford
County, Maryland, was 0.16 fiber/ml. Chrysotile fiber concentrations
measured at different distances downwind of the roadways ranged from
0.04 fiber/ml to 2.52 fibers/ml. These downwind concentrations resulted
after approximately 30 vehicle passes (at 30 mph) were made across dry,
unpaved road surfaces during a 2-hour sampling period.
3. No statistically significant relationship was found for fiber
concentrations versus receptor distance downwind, chrysotile content of
the roadstone, traffic volume, or wind speed because of variation in the
sampling data.
. 4. Results support the conclusion made earlier by the Montgomery
County Department of Environmental Protection that serpentinite quarries
are not a major source of airborne asbestos to the surrounding area.
Chrysotile concentrations measured near two serpentinite quarries ranged
from 0.01 to 0.35 fiber/ml with a geometric average of 0.04 fiber/ml.
5. The chrysotile concentrations reported in this study underestimate
the true potential for asbestos exposure from unpaved roads surfaced with
serpentinite. TEM analysis revealed that many of the particulate samples
contained bundles and sheaves of fibers that have the potential to split
into many fibrils. Numerous fibers may eventually be released from a
single bundle of fibers. Also, chrysotile fibers that were obscurred by
the presence of other material on the filter preparations could not be
counted.
6. Fiber concentrations reported in this study are not comparable
to fiber concentrations determined by phase-contrast microscopy. Nearly
all the fibers detected were short, thin fibers (less than 5 urn in length
and less than 0.1 urn in diameter) that would not be counted by phase
contrast microscopy because of procedural and analytical limitations.
7. Chrysotile fiber concentrations near campsites in the Clear
Creek Recreation Area are approximately 100 times greater than average
ambient background concentrations observed at the test sites located in
Harford County, Maryland.
B-20
-------
TABLE B-l. ANALYSIS OF EIGHT CRUSHED STONE SAMPLES FOR CHRYSOTILE FIBER
AND MASS CONTENT PERFORMED BY THE UNIVERSITY OF MINNESOTA AT DULUTH
Sample
number
[R-l]
[R-4]
[R-5]
00
1
I\J
[R-7]
[R-8]
[R-9]
[R-10]
[R-n]
Site and date
Clear Creek Road
11/16/79
Wood Creek Quarry
12/12/79
Duffy Road
12/08/79
McNabb Road
09/05/79
Holy Cross Road
10/18/79
Holy Cross Road
09/26/79
Clear Creek camping area
12/18/79
Holy Cross Road
09/05/79
Weight of
sample
analyzed (g)
2.19 E-7
8.50 E-5
2.455 E-6
8.67 E-5
3.955 E-5
9.62 E-5
9.12 E-6
8.96 E-6
Total
fiber
mass (ug/g)
3.39 E 5
1.30 E 2
1.24 E 4
2.33 E 3
1.95 E 3
2.93 E 3
1.49 E 3
1.88 E 3
Chrysotile
fiber
mass (ug/g)
3.25 E 5
9.41 E 1
6.56 E 3
5.74 E 2
3.34 E 2
2.57 E 2
7.40 E 2
1.38 E 3
% Chrysotile
of total
fiber mass
95.5
72.4
52.9
24.6
17.1
8.8
49.7
73.4
% Chrysotile
sample
analyzed
33.0
0.01
0.66
0.06
0.03
0.03
0.07
0.14
-------
TABLE B-2. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM HOLY CROSS ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of
Location Sampler
25 m MI
upwind
15 m mi
downwind m2
31 m mj
downwi nd
m2
m3
61 m ml
downwi nd m2
road stone:
Volume
sampled
(m3)
10.85
10.86
10.85
10.66
10.84
10.84
10.80
10.80
Holy
016
09/1
30
6-8
3.9
0.14
Filter
228
229
230
231
324
325
273
232
274
275
Cross Road
9/79 10:15-12:15
m/s
percent
percent
Laboratory3
ORF
DRI
DRI
DRI
DRI
ORF
DRI
ORF
ORF
DRI
Chrysotile
concentration
(fibers/ml)
0.00
1.17
1.09 .
1.13 (avg. )b
0.80
1.59
0.68
1.32
0.80
0.74 (avg.)d
0.45
0.92
0.64 (avg.)D
ORF = Ontario Research Foundation.
DRI = Denver Research Institute.
""Geometric average.
B-22
-------
TABLE B-3. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM HOLY CROSS ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of road stone:
Holy Cross Road
017
09/19/79 13:30 to 15:30
12
7-9 ra/s
2.5 percent
0.14 percent
Location
Sampler
Volume
sampled
(m3)
Filter
Laboratory0
Chrysotile
concentration
(fibers/ml)
25 m
upwi nd
15 m
downwi nd
mi
31 m
downwi nd
61 m
downwi nd
mi
m3
mi
10.80
10.80
10.85
10.84
10.84
10.85
10.84
10.71
10.71
321
233
320
234
235
236
237
238
276
239
277
278
327
328
DRI
DRI
ORF
DRI
DRI
ORF
ORF
DRI
ORF
DRI
DRI
DRI
DRI
ORF
0.36
0.98
0.02
0.04 .
0.13 (avg.)D
1.09
1.23
0.47
0.86 (avg.)b
0.75
0.49
0.75 h
0.65 (avg.T
0.88
0.76
0.91
0.24 .
0.62 (avg.)1
ORF = Ontario Research Foundation.
DRI = Denver Research Institute.
Geometric average.
B-23
-------
TABLE B-4. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSION FROM HOLY CROSS ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of road stone:
Holy Cross Road
018
09/19/79 16:25 to 18:25
20
6-9 m/s
3.3 percent
0.14 percent
Location
Sampler
Volume
sampled
(m3)
Filter
Laboratory6
Chrysotile
concentration
(fibers/ml)
25 m
upwind
15 m
downwi nd
31 m
downwi nd
m3
10.85
10.85
10.80
10.80
10.84
10.84
10.84
240
241
242
243
244
279
281
245
246
326
ORF
DRI
ORF
DRI
ORF
DRI
DRI
DRI
ORF
ORF
0.02
0.03 .
0.02 (avg.V
1.87
1.34
1.58 (avg.)1
1.09
2.10
2.52
1.98
0.73
1.15
1.46 (avg.)1
61 m m^
downwi nd m5
L 10.76
, 10.75
280
282
DRI
ORF
1.33
0.92 .
1.11 (avg.)
ORF = Ontario Research Foundation.
.DRI = Denver Reserach Institute.
Geometric average.
NOTE: Total suspended particulate concentrations determined for the
6 hours of sampling (runs 016, 017, and 018) on 9/19/79 were as
follows: 25 m upwind--30 pg/m3; 15 m downwind—471 M9/m3;
31 m downwind—312 ug/m3; 61 m downwind—230
B-24
-------
TABLE B-5. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM HOLY CROSS ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of road stone:
Holy Cross Road
027
09/26/79 12:55 to 14:55
20
3-5 m/s
3.0 percent
0.03 percent
Location Sampler
25 m nig
upwi nd
15 m m2
downwi nd
Volume
sampled
(m3) Filter
10.85 247
10.80 249
319
Laboratory
DRI
ORI
ORF
Chrysotile
concentration
(fibers/ml)
1.22
1.37
0.26
31 m
downwind
10.84
10.75
318
250
251
252
DRI
ORF
DRI
ORF
ORF = Ontario Research Foundation.
DRI = Denver Research Institute.
Geometric average.
1.42 .
0.80 (avg.)E
0.13
0.73
0.14
0.24 (avg.V
61 m
downwi nd
mi
ITI2
10.80
10.80
316
317
ORF
DRI
0.04
0.52 ,
0.14 (avg.)D
B-25
-------
TABLE B-6. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM HOLY CROSS ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of road stone:
Holy Cross Road
032
10/18/79 10:42 to 12:42
20
2-4 m/s
3.6 percent
0.03 percent
Location
Sampler
Volume
sampled
(m3)
Filter Laboratory
Chrysotile
concentration
(fibers/ml)
25 m
upwind
10.76
200
206
DRI
DRI
a
ORF = Ontario Research Foundation.
DRI = Denver Research Institute.
Geometric average.
0.68
0.33
0.47 (avg.y
15m m^
downwi nd
31 m tri}
downwi nd
ID 2
mo
10.35
10.71
10.68
10.71
202
203
207
204
205
DRI
DRI
DRI
ORF
DRI
2.09
1.60
0.44
0.05
0.48
0.64
r^
(avg.)b
B-26
-------
TABLE B-7. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM HOLY CROSS ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of
Location Sampler
25 m mt
upwi nd
15 m TO!
downwind m2
road stone:
Volume
sampled
(m3)
10.75
10.84
10.84
Holy Cross Road
034
10/18/79 13:25 to 15:
30
1-4 m/s
3.6 percent
0.03 percent
Filter Laboratory3
209 ORF
210 ORF
211 ORF
25
Chrysotile
concentration
(fibers/ml)
0.01
0.26
0.28
31 m
downwi nd
10.66
10.91
323
322
214
213
212
ORF
DRI
ORF
ORF
DRI
0.29
0.45
0.31 (avg.)c
0.16
0.08
1.10
0.25 (avg.)1
ORF = Ontario Research Foundation.
DRI = Denver Research Institute.
Geometric average.
B-27
-------
TABLE B-8. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM HOLY CROSS ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of road stone:
Holy Cross Road
035
10/18/79 16:08 to 18:08
30
2-3 m/s
3.6 percent
0.03 percent
Location
25 m
upwi nd
Volume
sampled
Sampler (m3)
m2 10.80
Filter
216
217
Laboratory3
ORF
ORF
Chrysotile
concentration
(fibers/ml)
0.05
0.03
15 m
downwi nd
31 m
downwind
61 m
downwi nd
10.85
10.76
10.71
10.94
218
221
222
224
225
DRI
DRI
ORF
DRI
DRI
0.04 (avg.)b
1.07
0.99
0.76
0.87 (avg.)b
0.41
1.03
0.65 (avg.)b
ORF = Ontario Research Foundation.
.DRI = Denver Research Institute.
Geometric average.
NOTE: Total suspended particulate concentrations determined for the
6 hours of sampling (Runs 032, 034, and 035) on 10/18/79 were as
follows: 25 m upwind—91 ug/m3; 15 m downwind—593 ug/m3;
31 m donwind—292 ug/m3; 61 m donwind—205 ug/m3.
B-28
-------
TABLE B-9. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM McNABB ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of road stone;
McNabb Road
013
09/18 10:00 to 12:00
20
3-10 m/s
4.8 percent
0.06 percent
Location
28 m
upwind
14 m
downwi nd
Vol ume
sampled
Sampler (m3)
mt 10.84
m! 10.86
m3 10.80
Filter
265
266
264
Laboratory3
DRI
ORF
DRI
Chrysotile
concentration
(fibers/ml)
1.41
0.96
1.50
1.18 (avg.)D
aORF = Ontario Research Foundation.
.DRI = Denver Research Institute
Geometric average.
B-29
-------
TABLE B-10. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM McNABB ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of road stone:
McNabb Road
014
09/18/79 12:45 to 14:45
15
7-9 m/s
3.7 percent
0.06 percent
Location
28 m
upwi nd
14 m
downwi nd
Volume
sampled
Sampler (m3)
m2 10.80
mt 10.84
m2 10.84
m3 10.85
Filter
331
263
267
268
269
329
270
Laboratory3
ORF
DRI
DRI
DRI
ORF
ORF
ORF
Chrysotile
concentration
(fibers/ml)
0.00
1.05
0.10 (avg.
1.49
1.98
0.69
0.60
0.55
0.92 (avg.
)b
)b
ORF = Ontario Research Foundation.
DRI = Denver Research Institute.
'Geometric average.
B-30
-------
TABLE B-ll. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM McNABB ROAD
Site:
Run:
Date and time:
Vehicle passes
Wind speed:
Road silt:
Chrysotile content of road stone:
McNabb Road
015
09/18/79 15:25 to 17:25
30
7-10 m/s
4.1 percent
0.06 percent
Location
28 m
upwi nd
14 m
downwi nd
Volume
sampled
Sampler (m3)
m3 10.80
m2 10.84
m3 10.84
Filter
260
262
272
Laboratory3
DRI
ORF
DRI
Chrysotile
concentration
(fibers/ml)
0.05
0.88
1.22 .
1.04 (avg.)D
ORF = Ontario Research Foundation.
DRI = Denver Research Institute
NOTE: Total suspended particulate concentrations determined for the
6 hours of sampling (Runs 013, 014, and 015) on 9/18/79 were as
follows: 28 m upwind—26 ug/m3; 14 m downwind—528 pg/m3.
B-31
-------
TABLE B-12. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM McNABB ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of road stone:
McNabb Road
020
09/20/79 10:50 to 12:50
29
2-4 m/s
3.2 percent
0.06 percent
Location
28 m
upwi nd
14 m
downwi nd
Volume
sampled
Sampler (m3)
m2 10.80
m2 10.85
Filter
284
285
290
Laboratory3
DRI
DRI
DRI
Chrysotile
concentration
(fibers/ml)
0.17
1.54
1.30
1.41 (avg.)b
DRI = Denver Research Institute.
Geometric average.
B-32
-------
TABLE B-13. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM McNABB ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of road stone:
McNabb Road
021
09/20/79 13:20 to 15:20
30
2-5 m/s
4.9 percent
0.06 percent
Location Sampler
28 m m1
upwind
14 m mt
downwi nd
m2
Vol ume
sampled
(m3)
10.85
10.86
10.80
10.82
Filter
291
286
289
288
287
«*
Laboratory
ORF
ORF
ORF
ORF
DRI
Chrysotile
concentration
(fibers/ml)
0.01
0.70
1.03
0.77
1.10 ,
0.88 (avg.r
aORF = Ontario Research Foundation.
.DRI = Denver Research Foundation.
Geometric average.
B-33
-------
TABLE B-14. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM McNABB ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of road stone:
McNabb Road
022
09/20/79 15:55 to 17:55
30
3-5 m/s
3.5 percent
0.06 percent
Location Sampler
28 m
upwind
it's
14 m m3
downwi nd m2
aORF =
DRI =
NOTE:
Ontario Research
Denver Reserach
Total suspended
Volume
sampled
(m3)
10.85
10.80
10.80
Foundation.
Institute.
parti cul ate
Chrysotile
concentration
Filter Laboratory (fibers/ml)
294
293
292
concentrations
DRI 0.29
ORF 1.16
DRI 1.16
determined for the
6 hours of sampling (runs 020, 021 and 022) on 9/20/80 were as
follows: 28 m upwind--36 ug/m3; 14 m downwind--509 ug/m3.
B-34
-------
TABLE B-15. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS FROM McNABB ROAD
Site:
Run:
Date and time:
Vehicle passes:
Wind speed:
Road silt:
Chrysotile content of road stone:
McNabb Road
031
09/27/79 14:00 to 16:00
25
1-4 m/s
3.7 percent
0.06 percent
Location
14 m
upwi nd
28 m
downwi nd
Volume
sampled
Sampler (m3)
m2 10.84
m2 10.80
m2 10.80
m3 10.80
Filter
303
299
300
298
Laboratory3
ORF
DRI
ORF
ORF
Chrysotile
concentration
(fibers/ml)
0.00
1.78
1.04
0.84 .
1.16 (avg.r
ORF = Ontario Research Foundation.
.DRI = Denver Research Institute.
Geometric average.
B-35
-------
TABLE B-16. SAMPLING AND ANALYSIS OF AMBIENT CHRYSOTILE ASBESTOS
CONCENTRATIONS IN THE CLEAR CREEK FEDERAL RECREATIONAL AREA,
SAN BENITO COUNTY, CALIFORNIA
Location
Camping area
Date
(1979)
12/15
Filter
73
145C
74
Sampling
duration
(minutes)
263
263
267
Total
volume
sampled
(m3)
0.419
0.419
0.566
Chrysotile b
concentration
(fibers/ml)
aAll samples collected using personnel air samplers with air flow rate
,of approximately 2 Ji/min.
Analyses performed by Denver Research Institute.
JjSplit sample of Filter 73.
Geometric average.
(Note: On the day of sampling, approximately 40 visitors were
in the area. The wind was from the SW, 1-3 m/s. Soil surface
were very dry.)
B-36
-------
TABLE B-17. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS NEAR A SERPENTINITE QUARRY IN THE EASTERN UNITED STATES
Date
(1979)
09/26
10/17
10/18
Run
029
033
036
036
Wind
direction
and speed
N, 3-5 m/s
SW, 0-3 m/s
N, 0-4 m/s
Sam-
pler
"»i
n>2
mi
ti\2
mi
IT12
Volume
sampled
Cm3)
43.30
42.44
44.25
45.15
44.88
44.52
Filter
295
314
305
304
306
307
309
308
Labora-
tory
DRI
ORF
ORF
DRI
ORF
ORF
ORF
DRI
unrysotile
concen-
tration
(fibers/ml)
0.35
0.09
0.01
0.04
0.01
0.01
0.01
0.13
0.03 (avg.)c
uAll samples were collected approximately 400 m south of Cedar Hill Quarry.
ORF = Ontario Research Foundation.
DRI = Denver Research Institute
Geometric average.
B-37
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TABLE B-18. SAMPLING AND ANALYSIS OF CHRYSOTILE ASBESTOS
EMISSIONS NEARS A SERPENTINITE QUARRY IN THE WESTERN UNITED STATES
Date Sam- Volume
(1979) Run plera sampled (m3)
12/12 C-08 m4 20.27
12/12 C-08 n>2 20.27
12/13 C-09 mt 28.48
12/13 C-09 m2 28.86
12/13 C-09 m3 18.43
12/13 C-09 4 26.86
Filter
58
134
142
68
143
66
70
135
71
144
Chrysotile
Labora- concentration
tory (fibers/ml)
ORF
ORF
ORF
ORF
DRI
DRI
DRI
DRI
ORF
ORF
0.04
0.10
0.04
0.03
0.05
0.11
0.06
0.06
0.06
0.03
0.05 (avg.)
All samples collected approximately 200 m downwind of Woods Creek Quarry,
Tuolumne County, California. On both sampling days wind was from the
.north at 2-4 m/s.
ORF = Ontario Research Foundation.
CDRI = Denver Research Institute.
Geometric average of the ten samples.
B-38
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TABLE B-19. STATISTICAL EVALUATION OF CHRYSOTILE
FIBER CONCENTRATIONS REPORTED BY TWO
LABORATORIES ANALYZING SPLIT AND COLOCATED SAMPLES5
Type of sample
Split samples
Colocated samples
Coefficient of
Comparison variation (%)
Within ORFb
Within DRIC
Between labs
Within ORF
Within DRI
Between labs
40
44
67
34
50
72
Interval
length (%)a
80
88
134
68
100
144
Interval length = Percent of the true value within which two test results
.should fall 90 percent of the time.
ORF = Ontario Research Foundation.
DRI = Denver Research Institute
B-39
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8.8 REFERENCES
1. Electron Microscope Measurement of Airborne Asbestos Concentrations—A
Provisional Methodology Manual. U.S. Environmental Protection
Agency. Research Triangle Park, N.C. Publication No. EPA-600/2-77-178.
Revised June 1978. 48 p.
2. Fitzpatrick J. Analysis of Airborne Particulate Samples for Asbestos.
Denver Research Institute. Denver, Colo. July 7, 1981.
3. Dillon, M. J., and P. Richardson. Asbestos Analyses for Ambient
Monitoring Study of Production and Use of Crushed Stone. Ontario
Research Institute. Mississauga, Ontario. June 25, 1981. 88 p.
4. Marklund, D., et al. Analysis of Crushed Rock Sample Specimens for
Measurement of Asbestos Content by Electron Microscopy. Environmental
Services Laboratory, University of Minnesota, Duluth. Duluth, Minn.
May 14, 1981. 11 p.
5. Memo from Fitz-Simons, T., EPA/ARB, to Drago, R., EPA:EMSL.
May 4 1981. Statistical evaluation of asbestos sampling results.
11 p.
B-40
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-450/3-81-006
3. RECIPIENT'S ACCESSION NO.
TITLE AND SUBTITLE
Assessment and Control of Chrysotile Asbestos Emissions
from linpaved Roads
5. REPORT DATE
May 1981
S. PERFORMING ORGANIZATION CODE
AUTHOR(S)
Robert K. Serra
Michael A. Connor, Jr.
8. PERFORMING ORGANIZATION REPORT NO.
, PERFORMING ORGANIZATION NAME AND ADDRESS
MIDWEST RESEARCH INSTITUTE
4505 Creedmoor Road, Suite 202
Raleigh, N.C. 27612
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-02-3059
ESED Project No. 77/6
2. SPONSORING AGENCY NAME AND ADDRESS
Industrial Studies Branch
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/200/04
9. SUPPLEMENTARY NOTES
U.S. EPA Project Officer—William Larry Elmore, Emission Standards and Engineering Div.
O. ABSTRACT
This document summarizes the findings of field surveys and a test program to assess
chrysotile asbestos emissions generated by vehicular use of unpaved roads surfaced with
crushed serpentinite rock. Included in this document are discussions of Federal
asbestos regulations, sampling and analysis procedures, human health effects, and
various emission control techniques. EPA believes that asbestos emissions which
occur from unpaved roads and other dusty sources surfaced with serpentinite should be
reduced to the greatest extent practical. Local, State, and Federal agencies respon-
sible for road maintenance 1n the limited areas where asbestos emissions occur are in
the best position to assess local conditions and implement the most appropriate control
measures.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Croup
Chrysotile asbestos
Air pollution
Fugitive dust
Asbestos
Hazardous pollutants
Unpaved roads
Control methods
Air pollution control
13 B
18. OiSTS!BUT;QN STATEMENT
Unlimited. Available from National Technical
Information Service, 5285 Port Royal Road,
Springfield, Virginia 22161
19. SECURITY CLASS fThu Report)
Unclassified
20. SECURITY CLASS (This pagei
Unclassified
21. NO. OF PAGES
105
22. PRICE
Form 2270-1 (R«». 4-77) previous SOITION is OBSOLETE
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