ASBESTOS EXPOSURE ASSESSMENT
Prepared by
ICF Incorporated
Prepared for
Dr. Kin Wong
Chemical Engineering Branch
Office of Pesticides and Toxic Substances
U.S. Environmental Protection Agency
Washington, D.C. 20460
March 21, 1988
REVISED REPORT
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TABLE OF CONTENTS
Page
LIST OF TABLES viii
EXECUTIVE SUMMARY , xii
I. INTRODUCTION 1
A. Approach • i
1. Availability of Occupational Exposure Data :. . 3
a. Asbestos Exposure Survey 3
b. OSHA Compliance Inspections 8
c. NIOSH and Other Studies 10
d. Summary 11
2. Analysis of Occupational Exposure Data 13
a. Current Exposure Levels 13
b. Populations Exposed/Duration and Frequency of
Exposure 15
c. Proj ected Exposure Levels 16
B. Conversion Factor for Asbestos Measurement '17
C. Report Format 21
II. OCCUPATIONAL EXPOSURE 23
A. Mining and Milling 24
1. Process Description 24
a. Conventional "Dry" Processing 24
b. Unconventional "Wet" Processing 26
c. Exposure Controls 26
2. Manufacturers and Production 28
3. Current Exposures 28
a. KCAC Incorporated 31
b. Calaveras Asbestos, Ltd 35
c. Vermont Asbestos Group 42
4. Summary 45
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TABLE OF CONTENTS
(Continued)
B. Product Manufacture
1. Paper Products .
a. Product Descriptions
(1) Millboard
(2) Pipeline Wrap
(3) Beater-Add Gaskets
(4) High-Grade Electrical Paper
(5) Specialty Papers
b. Process Descriptions
(1) Primary Manufacture
(2) Secondary Manufacture
c. Production and Employment
d. Exposure Profile
2. Asbestos-Cement Pipe
a. Product Description
b. Process Description
c. Exposure Profile ...
3. Asbestos-Cement Sheet
a. Product Descriptions
b. Process Descriptions
c. Exposure Profile ....
4. Friction Products
a. Product Descriptions
(1) Drum Brake-Linings
(2) Disc Brake Pads (Light and Medium)
(3) Disc Brake Pads (Heavy)
(4) Brake Blocks
(5) Clutch Facings
(6) Automatic Transmission Components
(7) Friction Materials
b. Process Descriptions
(1) Primary Manufacture
(2) Secondary Manufacture
c. Production and Employment
d. Exposure Profile
(1) Primary Manufacture
(2) Secondary Manufacture
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TABLE OF CONTENTS
(Continued)
Page
5. Textiles 84
a. Product Descriptions 84
b. Process Descriptions 86
(1) Primary Manufacture 86
(2) Secondary Manufacture 88
c. Exposure Profile '..,. 88
6. Sheet Gaskets and Packing 91
a. Product Descriptions 91
b. Process Descriptions 92
(1) Primary Manufacture 92
(2) Secondary Manufacture 92
c. Exposure Profile 93
(1) Primary Manufacture 93
(2) Secondary Manufacture 95
7. Roof Coatings, Non-Roofing Coatings, Missile Liner
and Sealant Tape 95
a. Product Descriptions 95
b. Process Descriptions 98
c. Exposure Profile 98
8. Asbestos-Reinforced Plastics 101
a. Product Description 101
b. Process Descriptions 102
(1) Primary Manufacture 102
(2) Secondary Manufacture 102
c. Exposure Profile 103
9. Miscellaneous Products 106
a. Production Data 106
b. Product Descriptions 107
(1) Filler Acetylene Cylinders 107
(2) Battery Separators 117
(3) Arc Chutes . 109
C. Chlorine Manufacture (Asbestos Diaphragm Cells) 109
1. Process Description 109
2. Manufacturers Using Asbestos Diaphragms Ill
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QF CONTENTS
(Continued)
3. Exposure Profile
4. Frequency and Duration of Exposure ..
D. Brake Repair Service
1. Exposure Setting/Process Description
a. Compressed Air/Solvent Mist . .
b. Brush
c. Water Spray/Rag
d. Brake Washer
e. Vacuum Unit Without Enclosure
f. Vacuum Unit With Enclosure ...
2. Current Exposures
3. Populations Exposed
a. Duration of Exposure for One Brake Job .
b. Full-Time Equivalent Populations
(1) Drum Brake Linings for Automobiles
(2) Disc Brake Linings for Automobiles
(3) Drum Brake Linings for Trucks
(4) Disc Brake Pads for Trucks
4. Frequency and Duration of Exposure ...
5. Summary
E. Construction Industry Exposure
1. Exposure Settings and Operations
2. Pre-0.2 f/cc PEL Exposures
3. Projected Post-0.2 f/cc PEL Exposures
4. Populations Exposed
5. Frequency and Duration of Exposure ..
6. Summary
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OF CONTENTS
(Continued)
Page
III. AIR RELEASES ." 163
A. Milling and Primary Manufacturing Emissions 163
1. Methodology 163
a. Operating Schedule 165
b. Quantity of Asbestos Collected by the
Control Device 165
c. Collection Efficiency of the Control Device 166
2. Emission Estimates 169
B. Secondary Manufacturing Emissions 176
1. Methodology 176
2. Emission Estimates 177
C. Mining and Trade Use Emissions 181
1. Methodology 185
2. Emission Estimates 188
a. Mining 189
b. Brake Repair 191
c. Construction 200
D. Emissions from Asbestos-Containing Waste Piles 203
1. Regulations Affecting Management of Asbestos Wastes .... 203
a. Mining and Milling Wastes 203
b. Manufacturing and Fabricating Wastes 205
c. Installation Wastes 206
d. Demolition and Renovation Wastes 207
2. Emission Estimates from Mining/Milling Waste Piles 208
a. Potential Emission Points During Waste
Handling Operations 209
b. Methodology 212
c. Emission Estimates 213
REFERENCES 217
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QF CONTENTS
(Continued)
APPENDIX A. OCCUPATIONAL EXPOSURE PROFILES AND AIR RELEASES FOR
"PRODUCTS NO LONGER PRODUCED OR USED IN THE U.S
1. Occupational Exposure ..
a. Product Manufacture
(1) Paper Products
(2) Corrugated Asbestos Cement Sheets
(3) Vinyl-Asbestos Floor Tile
b. Construction Industry Exposure
(1) Exposure Settings and Operations
(2) Current Pre-0.2 f/cc PEL Exposures ...
(3) Projected Post-0.2 f/cc PEL Exposures
(4) Population Exposed ,
(5) Frequency and Duration of Exposure ..,
2. Air Releases
a. Primary and Secondary Manufacturing Sources
b. Construction Sources
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LIST OF TABLES
Page
Table ES-1 -- Summary of Occupational Exposures and Air Releases xv
Table 1 - - Summary of ICF Exposure Survey Results 4
Table 2 -- Availability of Occupational Exposure Data for
Primary Processors •.. 5
Table 3 -- Availability of Occupational Exposure Data for
Secondary Processors 7
Table 4 - - Annual Domestic Production of Asbestos Fiber for 1985 .. 29
Table 5 -- Asbestos Exposure Profile for the Mining and Milling
Operations at KCAC Incorporated 32
Table 6 -- Asbestos Exposure Profile for the Mining and Milling
Operations at Calaveras Asbestos, Ltd 37
Table 7 -- Asbestos Exposure Profile for the Mining and Milling
Operations at the Vermont Asbestos Group 44
Table 8 -- Production and Employment for Primary Manufacture
of Paper Products 54
Table 9 - - Exposure Profile for Paper Products 56
Table 10 -- Exposure Profile for A/C Pipe -- Primary Manufacture ... 63
Table 11 - - Exposure Profile for A/C Sheet - - Primary Manufacture .. 68
Table 12 - - Production and Employment for Primary Manufacture of
Friction Products 76
Table 13 -- Exposure Profile for Friction Products --
Primary Manufacture 79
Table 14 -- Exposure Profile for Friction Products --
Secondary Manufacture and Rebuilding 82
Table 15 - - Exposure Profile for Textiles 89
Table 16 •- Exposure Profile for Sheet Gaskets and Packings 94
Table 17 - - Production and Employment for Coating Type Products .... 97
Table 18 - - Exposure Profile for Coatings -- Primary Manufacture ... 99
Table 19 -- Exposure Profile for Asbestos-Reinforced Plastics 104
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LIST OF TABLES
(Continued)
Table 20 - - Production Data for Miscellaneous Products
Table 21 -- Producers of Chlorine Using Asbestos Diaphragms ....
Table 22 - - Chlorine Production/Asbestos Fiber Consumption ......
Table 23 -- 'Exposure Profile for Asbestos Diaphragm Cells
Table 24 -- Asbestos Exposure During Brake Servicing,
by Control Method
Table 25 -- Summary of Asbestos Exposure by Control Method,
With Calculated Means
Table 26 •- Facilities Where Brake Repair is Performed
(1984 Data)
Table 27 -- Area Asbestos Concentration During Brake Servicing .
Table 28 -- Automobile Drum Brake Shoe Repair by Facility Type
and Estimated Full-Time Equivalent Workers Exposed
to Asbestos
Table 29 -• Automobile Disc Brake Pad Repair by Facility Type
and Estimated Full-Time Equivalent Workers Exposed
to Asbestos
Table 30 -- Truck Drum Brake Lining Repair by Facility Type
and Estimated Full-Time Equivalent Workers Exposed
to Asbestos
Table 31 -- Truck Disc Brake Pad Repair by Facility Type and
Estimated Full-Time Equivalent Workers Exposed to
Asbestos
Table 32 -- Pre-0.2 f/cc PEL Exposures to Asbestos Products in
the Construction Industry
Table 33 -- Projected Exposures to Asbestos Products in the
Construction Industry
Table 34 - - FTE Populations in the Construction Industry
Table 35 -- Summary of Occupational Exposure to Asbestos in
the Construction Industry
Table 36 -- Asbestos Emissions from Milling and Primary
Manufacturing Sources
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LIST OF TABLES
(Continued)
Page
Table 37 -- 1981 Primary Manufacturer Asbestos Consumption
and Waste Generation 173
Table 38 -- Asbestos Emissions from Secondary Manufacturing
Sources , . . 178
Table 39 -- 1981 Secondary Manufacturer Asbestos Mixture
Consumption and Waste Generation 179
Table 40 -- Asbestos Emissions from Mining Sources 190
Table 41 -- Distribution of Brake Repair Work by Types of
Facilities 192
Table 42 - - Asbestos Emissions from Brake Repair 195
Table 43 -- Asbestos Emission Estimates in g/yr for Each Region --
Installation of Drum Brake Shoes on Cars 196
Table 44 -- Asbestos Emission Estimates in g/yr for Each Region --
Installation of Drum Brake Shoes on Trucks 197
Table 45 -- Asbestos Emission Estimates in g/yr for Each Region --
Installation of Disc Brake Pads on Cars 198
Table 46 -- Asbestos Emission Estimates in g/yr for Each Region --
Installation of Disc Brake Pads on Trucks 199
Table 47 -- Asbestos Emissions from Construction Activities 202
Table 48 - - Summary of Current Waste Generation from Milling
Operations 210
Table 49 -- Parameters for Estimating Emissions Resulting from
Wind Erosion 214
Table 50 -- Emission Estimates from Milling Waste Piles : 215
Table A-l -- Exposure Profiles for Paper Products No Longer
Manufactured in the U. S 237
Table A-2 -• Exposure Profile for Corrugated Asbestos Cement
Sheet - - Primary Manufacture 242
Table A-3 -- Exposure Profile for V/A Floor Tile -- Primary
Manufacture 246
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LIST OF TABLES
(Continued)
Table A-4 -- Exposure to Asbestos Floor Products in the Construction
Industry Under Pre-0.2 f/cc PEL
Table A-5 -- Exposure to Asbestos Floor Products in the Construction
Industry Under Post-0.2 f/cc PEL
Table A-6 -- Asbestos Emissions from Primary Manufacturing Sources
for Products No Longer Manufactured in the U.S
Table A-7 -- Asbestos Emissions from Secondary Manufacturing Sources
for Products No Longer Manufactured in the U.S
Table A-8 -- Asbestos Emissions from Construction Activities Using
Products No Longer Used in the U.S
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EXECUTIVE SUMMARY
EPA is assessing the risks associated with the production and use of
asbestos and of products made from asbestos. As background for EPA's January
29, 1986 proposal to ban and phase down asbestos production and usage,
occupational exposure levels and air releases for primary and secondary
processing of asbestos from 1981 8(a) submissions and exposure levels for
construction from the late 1970's and early 1980's were used. Recently OSHA
has lowered its permissible exposure limit (PEL) for asbestos to 0.2 f/cc from
the previous 2 f/cc. Because of OSHA's new PEL, additional controls and
respirators are likely to be used to reduce current exposure levels to the new
PEL or lower. The purpose of this study is to update occupational exposure
data and air emissions, used as inputs to determine ambient exposures, to
better represent current industry practices.
Available occupational exposure and air emission data from NIOSH,
academic, and industry studies were supplemented by OSHA Compliance data and
the IGF Exposure Survey. The ICF Exposure Survey, which covered both
occupational exposures and air releases, was sent to all miners/millers of
asbestos, primary and secondary manufacturers of asbestos products, and
several relevant industry groups. The overall positive response rate of this
voluntary survey was 14 percent (refer to Chapter I, Section A.I for a more
thorough discussion of the survey). OSHA Compliance data were supplied to us
by the OSHA Office of Management Data Systems for the SICs corresponding to
manufacturing, construction, and automotive servicing.
Due to the limited availability of exposure data on any one product, we
estimated exposure levels for product categories. However, these product
category exposures are applied to the worker populations, and population
distributions, for each individual product, thus allowing for some
distribution of risk. This analysis, however, assumes that job category
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exposures for all products in a product category are identical. The product
categories are:
Paper products;
Friction products;
Asbestos cement products;
Asbestos-reinforced plastics;
Coatings;
Packings and gaskets;
Textiles; and
Miscellaneous uses.
This analysis does not cover products no longer produced in the U.S. or
imported into the U.S. such as commercial paper, corrugated paper, rollboard,
flooring felt, roofing felt (imported only), corrugated A/C sheet (imported
only), and vinyl asbestos floor tile. Occupational exposure levels and
population factors for products no longer produced or used in the U.S. are
presented in Appendix A for use in sensitivity analysis.
Current exposure levels associated with each job category or task are
based on historical data. Both geometric and arithmetic means of the raw data
are presented throughout the text of this report (and in Appendix A). The
geometric mean represents a typical exposure level for a worker performing a
particular job, assuming that the observations follow a log normal
distribution which is common for exposure data. The arithmetic mean, which
represents the total worker exposure when multiplied by the exposed
population, is used in the health benefits model to assess the consequences of
exposure.
Total 1985 worker populations for primary and secondary product
manufacturing for each product are calculated by summing up the populations
for each producer gathered during the ICF Market Survey. These populations
are distributed into the various job categories identified by the monitoring
results using the population distributions obtained from 1981 TSCA Section
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8(a) submittals. Exposed populations for mining and milling were obtained
through telephone contacts with the respective company representatives.
Since installation, repair, and removal jobs are intermittent, populations
for brake repair and construction have been calculated as full-time
equivalents (FTEs). The FTE population is the number of workers working 250
days/year and 8 hours/day at installing, repairing, and removing the total'
quantity of an asbestos product manufactured or imported each year (from the
ICF Market Survey). Short-term exposures, which represent the exposure during
the period of time in which the actual task is performed, are applied to this
population.
We used a simplified and conservative approach for projecting exposure
levels under the 0.2 f/cc PEL. This approach assumes that for those
operations where 8-hour TWA exposures are currently below 0.2 f/cc, work
practices will remain unchanged. However, for those operations where the
8-hour TWA exposures are currently above 0.2 f/cc, work practices will be
changed either with the addition of engineering controls or respirators to
reduce the exposures to 0.2 f/cc.
Table ES-1 summarizes the occupational exposure results. Throughout the
asbestos manufacturing industry, exposure levels are a function of specific
job and product type. Activities with relatively high time-weighted average
exposures are fiber receiving and storage, fiber introduction and mixing, and
some finishing operations. Product characteristics also affect exposure
levels. In a product such as a coating, the asbestos is encapsulated thus
reducing its potential for release.
Air releases are estimated for each mining/milling and product
manufacturing facility using site specific data and engineering estimates of
baghouse collection efficiencies. Air releases from brake servicing and
construction are calculated as annual industry emissions due to the lack of
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Table ES-1. Sumnary of Occupational Exposures and Air Releases
Occupational Exposure
Exposure Level
(f/cc)'
Industry Sector Geometric Mean
Mining
Milling
Milling Waste Piles
Primary Product Manufacture
Paper Products
A/C Pipe
A/C Sheet
Friction Product*
Textiles
Gaskets end Packings
Coatings
Reinforced Plastics
Secondary Product Manufacture
Paper Products
Friction Products8
Textile*
Gaskets and Packings
Reinforced Plastic*
Chlorine Manufacture (Asbestos Diaphragms)
Brake Repair
Construction
0.02*
0.05£
N/A
0.04
0.08
o.ie
0.11
0.18
0.03
0.03
0.06
0.02
0.01
0.1S
0.08
0.07
0.02
0.09h
0.10
Arithmetic Mea
0.03f
0.06*
N/A
O.OS
0.10
0.18
0.1S
0.18
0.08
0.11
0.06
0.02
0.05
0.16
0.11
0.09
0.04
0,15h
0.13
Air Releases
Population 1
n Exposed
44
111
N/A
299
286
23
2,603
78
168
1,449
138
1,877
7,045
208
903
456
650
114,234
2,032
Duration of Exposure Total Emissions Duration of Emissions
(hours/yeer)c (kg/yr)d (hours/year)
900-1.600
1,490-1,920
N/A
1,630
2,000
2,000
2,000
1,920
2,000
1,720
2,000
2,000
2,000
2,000
2,000
2,000
1,760
2,000
2,000
11 (14)d
4.495
9
957
552
79
3,536
152
303
80
17
1,405
18
8
9
2
0.08
17 (23 )d
318 (422)d
900-1,600
8,760
8,760
8,760
8,760
6,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8.760
8,760
8,760
8,760
8,760
8.760
"Geometric and arithmetic means of available raw monitoring data projected under the 0.2 f/cc PEL. Exposure levels are 8-hour TKAs except for brake
repair and construction for which short-term exposures are used. Exposure levels are weighted arithmetically by the number of workers exposed to each
level in the Industry sector to determine the "average" values presented in this table.
Population figures are the summation of the number of exposed workers at each facility, except for brake repair and construction for which full-time
equivalent populations are presented.
CA default of 2,000 hours/year Is used when no other data are available. (The 8-hour TWA has been calculated such that It accounts for short dally
exposures, thereby making the effective duration of exposure 8 hours/day.)
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Table ES-1 (Continued)
dTotal emissions for mining, brake repair, and construction are based on the occupational exposure levels associated with each task; therefore, two
values are presented -- one using the geometric mean exposure and the other using the arithmetic mean exposure. The total emissions using the
arithmetic mean exposure are presented in parentheses.
8The duration of emissions Is 8,760 hours/year In all cases, except for mining, because emissions are modeled as continuous releases. The duration of
mining emissions Is the actual time spent on mining activities.
fAssumes use of respirators specified by the mining/milling companies.
8Includes both secondary processing and brake rebuilding.
Geometric and arithmetic mean exposure levels for brake service using various non-engineering and engineering controls were weighted arithmetically by
the estimated fraction of facilities using each control; the numbers given are the overall weighted geometric and arithmetic means, respectively.
4The population exposed during brake repair Includes not only the mechanics performing the brake Jobs, but also all other full-time mechanics
(full-time equivalents) in the brake servicing facilities. All full-time mechanics are Included because monitoring data show similar levels for area
exposure* as were observed for breathing zone exposures for workers performing brake Jobs.
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site specific information in these ubiquitous industries. Tables ES-1
summarizes the air release results.
This report is divided into three major chapters: Introduction,
Occupational Exposure and Air Releases. Chapter 1 presents our approach for
gathering and analyzing occupational exposure and air release data, and our
review of conversion factors for asbestos measurement. Chapter II presents
our estimates of occupational exposures during mining/milling, asbestos
product manufacture, chlorine manufacture using asbestos diaphragm cells,
brake repair, and construction. Each subsection includes a brief discussion
of the products included in each product category, the processes used to
manufacture the products or a description of the operations involved, current
and projected geometric mean exposure levels, populations exposed, and
duration and frequency of exposure.
Chapter III presents our estimates of air releases from milling, primary
manufacturing, and secondary manufacturing sources from stacks; and from
mining, brake repair, and construction as area releases. Each subsection
presents our methodology for estimating air emissions and our emission
estimates.
Appendix A presents geometric and arithmetic mean exposure levels,
population factors, and air emissions for production and use of asbestos
products no longer produced in or imported into the U.S. These data are
reported for use in sensitivity analysis to estimate likely occupational
exposures and air releases should these products be produced or used in the
U.S. in the future.
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I. INTRODUCTION
EPA is assessing the risks associated with the production and use of
asbestos and of products, made from asbestos. As background for EPA's January
29, 1986 proposal to ban and phase down asbestos production and usage, occupa-
tional exposure levels and air releases for primary and secondary processing
of asbestos from 1981 8(a) submissions and exposure levels for construction
from the late 1970's and early 1980's were used. Recently the Occupational
Safety and Health Administration (OSHA) has lowered its permissible exposure
limit (PEL) for asbestos to 0.2 f/cc from the previous 2 f/cc (OSHA 1986a).
Because of OSHA's new PEL, additional controls and respirators are likely to
be used to reduce current exposure levels to the new PEL or lower. The
purpose of this study is to update occupational exposure data and air
emissions, used as inputs to determine ambient exposures, to better represent
current industry practices.
A. Approach
Our approach was to identify and gather all available data from the
literature on occupational exposures and air emissions. We performed an
on-line literature search using the NIOSH, Pollution Abstracts, Enviroline,
and NTIS databases to identify NIOSH, academic, and industry studies on
asbestos exposures. In addition, we performed a search of all OSHA and
National Institute of Safety and Health (NIOSH) publications using the
NIOSH/OSHA publications index and the OSHA Technical Data Center's on-line
system. NIOSH reports include "Hazard Evaluation and Technical Assistance
Reports (HHEs)," "Industry Wide Study Reports (IWs)," "Control Technology
Reports (CTs or Walk-Through Survey Reports)," and "Contractor Reports." We
also gathered the Toxic Substances Control Act (TSCA) Section 8(a) data and
other literature referenced in the original "Exposure Assessment for
Asbestos," OSHA's background documents and docket on the new asbestos
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standard, and submittals related to occupational exposure and air releases to
EPA's docket. We also accessed the OSHA Computerized Information (OCIS) data
base developed in Salt Lake City under the SIC Industrial Hygiene (I.H.)
Information File; however, the data available on this system is so general
that it could not be accurately used to estimate exposures for specific
products. NIOSH is currently performing several site visits to better
characterize exposures from brake repair; three new brake repair reports have
been received from this effort to date.
Mining and milling exposure data are collected annually by the Mine Safet;
and Health Administration (MSHA). We received copies of all the data
available from MSHA for the asbestos mining/milling facilities. MSHA
regulates mining and milling operations and sets an exposure limit of 2 f/cc;
OSHA's new 0.2 f/cc PEL does not affect the miners and millers of asbestos.
We searched the literature for data on air releases, but found that the
best base of data for estimating air releases was the OAQPS draft background
document entitled "National Emission Standards for Asbestos -- Background
Information for Proposed Standards" and the Section 114 Letters. The draft
background document supplied baghouse efficiencies and stack information for
typical plants producing each primary product; these model plants include the
fiber consumption and the number of stacks with the corresponding flow rate
through each stack.
The available literature data are limited; therefore, we supplemented the
data by gathering OSHA Compliance data for asbestos (OSHA 1987) and
distributing a survey to all affected industry members identified in the ICF
Market Survey (1986-1987). The ICF Exposure Survey (1986-1987) was sent to
all miners/millers of asbestos, primary and secondary manufacturers of
asbestos products, and several relevant industry groups. OSHA Compliance dat,
(OSHA 1987) were supplied to us by the OSHA Office of Management Data Systems
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for the Standard Industrial Classifications (SICs) corresponding to
manufacturing, construction, and automotive servicing.
1. Availability of Occupational Exposure Data
This section summarizes the results of ICF's voluntary asbestos
exposure survey and the availability of occupational exposure data from the
ICF Exposure Survey; OSHA Compliance data; and NIOSH, industry, and academic
studies.
a. Asbestos Exposure Survey
Table 1 presents the results of the ICF Exposure Survey (1986-1987)
for mining/milling, primary processing, chlorine manufacture, and secondary
processing. The final column labeled "industry groups" was an effort to
obtain exposure data for downstream uses.
One of the 3 asbestos mining/milling companies responded to the survey,
for a positive response rate of 33 percent. This company, however, did not
provide monitoring data.
The survey was sent to the 135 active primary processors identified by the
ICF Market Survey (1986-1987). Many companies process asbestos in multiple
locations; the total number of plants represented by the primary processors is
183. Of these 135 companies, 31 responded to the survey in some way, for a
total response rate of 23 percent. However, only 15 of the facilities (or 11
percent) completed the survey to some degree. (Not every positive responder
provided exposure data.) Of the remaining respondents, 10 have ceased pro-
cessing asbestos and 6 refused to respond to the survey. Table 2 presents a
distribution of the positive responses by product category. Both an
indication of the number of plants and the number of companies are provided
for each product category.
The survey was sent to 17 chlorine manufactures, some of which may not be
using asbestos diaphragm cells. Of these 17 companies, 10 respondents
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Table 1. Summary of ICF Exposure Survey Results
Mining/ Primary Chlorine Secondary Industry
Milling Processing Manufacture3 Processing Groups
Number of Companies
That Received
Surveys
Number of Plants
Using Asbestos
Operated By These
Companies
Total Number of
Responses
135
183
31
17'
56'
10
87
101
21
11
N/A
Survey Completed
Ceased Production
Refusal
Percent Response
Rate
Survey Completed
Ceased Production
Refusal
1
-
-
33%
33%
-
•
15
10
6
23%
11%
7.5%
4.5%
10
-
-
59%
59%
-
•
7
13
1
24%
8%
15%
1%
-
-
-
0%
_
-
-
N/A - Not applicable.
aUse of asbestos diaphragms for chlorine manufacture.
"These numbers of companies and plants may include facilities that do not use
asbestos diaphragms.
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Table 2. Availability of Occupational Exposure Data for Primary Processors
Product Category
1CF Exposure
Survey
(Number
of Plants)a
OSHA Compliance
Inspections
(Number of
Plants)b
NIOSH Industry
Studies Group,
(Number Company, or
of Academic
Plants) Studies
Friction Materials
Sheet Gaskets
and Packings
Textiles
Roof Coatings and
Non-Roofing
Coatings
(3 inspections)
5 13
(4 companies) (19 inspections)
(6 inspections)
1 1
8 25
(6 companies) (33 inspections)
0
5
0
0
Total
Paper Products
A/C Pipe
A/C Sheet
2
1
0
3
2
2
0
0
0
0
1
0
5
4
2
21
2
38
Asbestos -
Reinforced
Plastics
Total
0
18
(15 companies)
0 0
51 9
(67 inspections)
0
1
0
79
aThe number of plants equals the number of companies responding to the survey
unless indicated otherwise. Many companies have multiple locations. (Note: Not
all survey responses were fully completed.)
"The number of inspections equals the number of plants unless specified otherwise.
Several facilities were inspected multiple times from 1979 to the present.
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completed the survey, for a response rate of 59 percent. Fifteen facilities
are represented by the 10 respondents; however, exposure data are limited for
a few of the facilities.
The survey was also sent to the 87 active secondary processors identified
by the ICF Market Survey (1986-1987). Many companies process asbestos in
multiple locations; the total number of plants represented by the secondary
processors is 101. Of these 87 companies, 21 responded to the survey in some
way, for a total response rate of 24 percent. However, only 7 of the
facilities (or 8 percent) completed the survey to some degree. (Not every
positive responder provided exposure data.) Of the remaining respondents, 13
have ceased processing asbestos and one refused to respond to the survey.
Table 3 presents a distribution of the positive responses by product category
Both an indication of the number of plants and the number of companies are
provided for each product category.
The exposure survey was sent to 11 industry groups in an effort to gather
exposure data for downstream uses. The following groups were sent surveys,
but none of them supplied any monitoring data:
c American Federation of State, County, and Municipal
Employees, Washington, D.C.;
• Asbestos Information Association, Arlington, VA;
• Asphalt Recycling and Reclaiming Association, Annapolis,
MD;
• Building and Construction Trades Department (AFL-CIO),
Washington, D.C.;
• Edison Electric Institute, Washington, D.C.;
• Electrical/Electronics Insulation Conference, Washington,
D.C.;
• Friction Materials Standards Institute, Paramus, NJ;
• Gasket Fabricators Association, Philadelphia, PA;
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Table 3. Availability of Occupational Exposure Data for Secondary Processors
Product Category
a
ICF Exposure
Survey
(Number
of Plants)b
OSHA Compliance
Inspections
(Number of
Plants)0
NIOSH Industry
Studies Group,
(Number Company, or
of Academic
Plants) Studies Total
Paper Products
Friction Materials
Asbestos -
Reinforced
Plastics
Missile Liner
Sheet Gaskets
1
2
0
1
4
0
2
0
0
8
1
1
2
0
0
0
0
0
0
0
2
5
2
1
12
and Packings
Textiles
TOTAL
(3 companies)
0
8
(7 companies)
11
25
aThe are fewer product categories for secondary processing because products such as
A/C pipe, roof coatings, and non-roof coatings do not require secondary processing.
In addition, there are currently no secondary processors of A/C sheet.
number of plants equals the number of companies responding to the survey
unless indicated otherwise. Many companies have multiple locations. (Note: Not
all survey responses were fully completed.)
cThe number of inspections equals the number of plants unless specified otherwise.
Several facilities were inspected multiple times from 1979 to the present.
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• International Association of Heat and Frost Insulators and
Asbestos Workers, Washington, D.C.;
• International Union, United Automobile, Aerospace, and
Agricultural Implement Workers of America, Detroit, MI; and
• Thermal Insulation Manufacturers Association, Mt. Kisco,
NY.
In a further effort to obtain downstream exposure data, we called:
(1) Electrical/Electronics Insulation Conference, Washington, D.C.; (2) Unit
Automobile Workers, Detroit, MI; (3) Friction Materials Standards Institute,
Paramus, NJ; (4) National Roofing Contractors Association, Chicago, IL; and
(5) Edison Electric Institute, Washington, D.C. Still, we were unable to
obtain any exposure data.
b. OSHA Compliance Inspections
We reviewed a printout of OSHA Compliance Inspection summaries
dated 1979 through 1986 for asbestos (OSHA 1987) to extract summaries that
applied to the scope of this exposure assessment. The printout was provided
by OSHA's Office of Management Data Systems for asbestos mining (SIC 1499),
construction (SICs 1520-1799), manufacturing (SICs 2210-3999), and auto repai
(SICs 4171, 4231, 5511, 5541, and 7510-7549).
No OSHA compliance data were found for asbestos mining and milling. This
is reasonable since the Mine Safety and Health Administration (MSHA) regulate
mining operations.
The OSHA compliance summaries for manufacturing totalled 920. We
cross-referenced the companies (and plant locations) inspected with the 1981
Section 8(a) list of primary and secondary processors of asbestos and with th
most recent list of processors from the ICF Market Survey (1986-1987).
Summaries for those companies and their respective plants that could be
identified on any one of the asbestos processor lists were extracted. Six
additional inspections for companies that appeared to be asbestos processors
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but could not be found on any of the lists were also extracted. (For an
exposure assessment, it is appropriate to use data for facilities that have
since ceased production because one cannot assume that facilities ceased
production due to their exposure levels being out of the normal range. It is
reasonable to assume that facilities ceasing production used similar process
technologies and engineering controls as are used by current manufacturers and
had exposure levels that are, therefore, representative of those experienced
by the remaining producers.) The company (and plant) inspections selected as
appropriate for the exposure assessment were further divided by primary and
secondary processing and by product category, using the Section 8(a) and ICF
Market Survey (1986-1987) data. Tables 2 and 3 present the distribution of
OSHA inspections by product category for primary and secondary processing,
respectively. Both an indication of the number of plants and the number of
inspections are provided for each product category; several plants were
inspected multiple times.
The remaining OSHA inspections for manufacturing appear to include
downstream users of asbestos products, and facilities that either do not use
asbestos but had concerned employees or have asbestos in either their
buildings or machinery (e.g., publishers). However, 12 of these inspections
appeared to be brake rebuilders based on either the company names or the job
categories. Words such as rebuilders, debonder, exchange, tear down,
stripper, and remanufacture in reference to brakes were used to select
appropriate companies for the brake rebuilding exposure assessment.
We were not quite so successful in our review of the 1096 OSHA inspections
for construction. The difficulties in this review were the vague nature of
the SIC categories and the nondescript company names. We found it difficult
to confidently say an inspection referred to a specific product category.
Also, in the vast majority of the inspections, the job titles seemed to refer
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to asbestos abatement rather than construction activities (e.g., insulation
remover, laborer scraper, asbestos remover), to activities where the worker is
indirectly exposed (e.g., boiler maker, electrician, HVAC technician,
plumber), or to applications using asbestos products no longer used in the
U.S. (e.g., insulator). IGF identified only 4 inspections that looked at all
applicable. After speaking with the OSHA regional offices to obtain further
information on the activities at the time of the inspections, this number was
reduced to only one usable inspection for A/C shingle tear-off. The OSHA
regional offices keep the original inspection files on hand for 3-4 years at
which time they are sent to the archives. Of the two that were more recent
than this, only the one had to do with one of the products we are currently
investigating.
The automotive repair printout yielded 82 inspections for automotive
repair, servicing, and garages; motor vehicle dealers; and terminal
maintenance facilities. (OSHA inspection data were also obtained for service
stations, but no relevant personal sampling results were identified). The
asbestos concentration was non-detectable for 86 out of 109 personal samples.
The 8-hour TWA for the remaining 21 personal samples ranged from 0.005 to
0.940 f/cc. These data are not included in our exposure estimate because of
the uncertainties associated with them. It was not possible to determine
whether or not the monitoring data were taken during brake repair operations;
data for job titles such as "worker" or "laborer" were presented with no
indication of the activity being performed. Even the mechanics may not have
been doing brake work at the time of. the inspection.
c. NIOSH and Other Studies
In addition to the data from the ICF Exposure Survey (1986-1987)
and the OSHA inspections (OSHA 1987), we collected NIOSH reports, contractor
reports, trade association studies, and company studies. The availability of
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these studies by product category for primary and secondary processing is
presented in Tables 2 and 3, respectively. We also have 3 NIOSH studies for
construction. For brake repair, there are 7 NIOSH studies, and for brake
rebuilding, there are 2 NIOSH studies. We have one NIOSH report and one trade
association report for chlorine manufacture using asbestos diaphragms. And
finally for mining and milling, MSHA supplied extensive monitoring data for
each company, and one company provided some of its own monitoring results.
d. SiifimiflT-y
A good quantity of exposure data is available for mining/milling,
primary manufacture of friction materials and coatings, and secondary
manufacture of sheet gaskets. Limited data are available for primary
manufacture of paper products, A/C pipe and sheet, packings and gaskets, and
textiles; secondary manufacture of paper products, friction materials
(including brake rebuilding), asbestos-reinforced plastics, coatings, and
textiles; construction using A/C products and roofing felts; and brake repair.
No exposure data are available for primary manufacture of asbestos-reinforced
plastics; exposure estimates for this product category, therefore, rely
heavily upon OSHA's recent assessment for the new PEL.
There are uncertainties surrounding each major type of exposure data:
data supplied by companies or industry groups such as those obtained in the
ICF Exposure Survey, OSHA compliance data, and NIOSH or academic studies. It
is believed that there are biases associated with each type of exposure data.
For example, OSHA compliance data is thought to represent high exposures
because OSHA is likely to focus its attention on facilities for which it
receives employee complaints or which have historically been out of
compliance. However, OSHA also performs random inspections at facilities
which have a greater likelihood of compliance than those for which complaints
are received. Conversely, company supplied data is thought to be biased
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towards facilities using best available control technologies and, therefore,
having low exposure levels. The basis for this belief is the unlikelihood
that facilities with high exposure levels would respond to a voluntary survey
and expose themselves as being out of compliance. Finally, NIOSH or academic
studies would likely focus on facilities or operations having high exposures
or on specific control technologies which would likely provide low exposure
levels (e.g., evaluation of vacuum systems to control exposures during brake
repair). To determine the significance of these potential biases in the data,
we evaluated the available exposure data for primary manufacture of friction
products. Primary manufacture of friction products was chosen for this
evaluation because of the wealth of available data from each type of source.
For two job categories, fiber introduction/mixing and finishing, the current
exposure data (pre-0.2 f/cc PEL) were segregated by the source type (i.e., ICF
Exposure Survey, OSHA compliance data, or NIOSH/academic studies), and
separate geometric means were calculated yielding the following results:
• Fiber Introduction/Mixing
-- ICF Exposure Survey: 0.329 f/cc
-- OSHA compliance data: 0.566 f/cc
-- NIOSH studies: 0.085 f/cc
Combination of sources: 0.251 f/cc
• Finishing
-- ICF Exposure Survey: 0.149 f/cc
-- OSHA compliance data: 0.424 f/cc
-- NIOSH studies: 0.193 f/cc
Combination of sources: 0.174 f/cc
The results indicate that there is somewhat of a bias in the data. In
general, OSHA coppliance data yield the highest geometric mean exposures,
while ICF Exposure Survey and NIOSH data yield comparable lower geometric mean
exposures. In the case of the NIOSH data for fiber introduction/mixing, the
geometric mean exposure is significantly lower than for the OSHA and ICF
Exposure Survey data because the bulk of the NIOSH data focused on evaluating
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the effectiveness of bag opening equipment to control airborne fibers. The
mix of the various data types for most product categories, however, minimizes
the effects of the biases, as indicated by the overall geometric mean levels
presented for friction products using a combination of sources.
2. Analysis of Occupational Exposure Data
a. Current Exposure Levels
For product manufacturing, a large quantity of exposure monitoring
data has been obtained. Due to the limited availability of exposure data on
any one product, we were only able to estimate exposure levels for product
categories. However, these product category exposures are applied to the
worker populations for each individual product, thus allowing for some
distribution of risk by product. This analysis, however, assumes that job
category exposures from all products in a product category are identical. The
product categories are:
Paper products;
Asbestos cement products;
Friction products;
Textiles;
Packings and gaskets;
Coatings;
Asbestos-reinforced plastics; and
Miscellaneous uses.
This analysis does not cover products no longer produced in the U.S. or
imported into the U.S. such as commercial paper, corrugated paper, rollboard,
flooring felt, roofing felt (imported only), corrugated A/C sheet (imported
only), and vinyl asbestos floor tile. Occupational exposure levels and
population factors for products no longer produced or used in the U.S. are
presented in Appendix A for use in sensitivity analysis.
Current exposure levels associated with each job category or task are
based on historical data. Both geometric and arithmetic means of the raw data
are presented throughout the text of this report (and in Appendix A).
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The traditional summary statistic used in industrial hygiene studies is
the geometric mean of the measured exposures. It appears that this value is
used because: (1) the distribution of exposures to toxic substances has been
found in other studies to follow a log normal distribution; and (2) the
geometric mean of a log normal distribution is the mode (most common single
value) of that distribution. The geometric mean is, therefore, the single
level of exposure that workers are more likely to be exposed to than any other
single level of exposure.
The geometric mean of exposure values would be the appropriate summary
statistic to use if our exposure concern centered on the level of exposure
typically encountered by a representative worker. In the case of asbestos,
however, the health benefits model used to assess the consequences of exposure
is a linear, no-threshold, dose-response model. Using a model of this type,
the total dose of asbestos fiber delivered to all workers determines the total
number of anticipated cases of lung cancer, mesothelioma, and cancers of the
gastrointestinal tract (Augustyniak 1987).
If the concern is with total dose, rather than with "typical" levels of
exposure, the useful summary statistic becomes the arithmetic mean of the
distribution of exposures rather than the geometric mean of those exposures.
The arithmetic mean of the distribution is the summary statistic which, when
multiplied by the number of exposed workers, yields the total amount of worker
exposure to asbestos (Augustyniak 1987).
The important summary statistic for the sampled population becomes that
summary statistic which is an unbiased estimator of the population mean. The
arithmetic mean of the sampled values is the unbiased estimator of the
population mean and, therefore, is used in the health benefits model to assess
the consequences of exposure (Augustyniak 1987).
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b. Populations Exposed/Duration and Frequency of Exposure
Total 1985 worker populations for primary and secondary product
manufacturing for each product are calculated by summing up the populations
for each producer gathered during the ICF Market Survey (1986-1987). These
populations are distributed into the various job categories identified by the
monitoring results using the population distributions obtained from the 1981
TSCA Section 8(a) submittals. When total populations are not available due to
refusal to respond to the ICF Market Survey (1986-1987), we applied a ratio of
number of workers to asbestos fiber consumption based on data received from
responding companies manufacturing the same or similar products. (Exposed
populations and duration and frequency of exposure for mining and milling were
obtained through telephone contacts with the respective company representa-
tives.) All exposure levels for mining, milling, and product manufacture are
converted to 8-hour time weighted averages (TWAs) such that the appropriate
duration of exposure for all job categories is 8 hours/day even if a worker is
actually only exposed for a short period of time. Eight-hour TWAs are
calculated from short-term exposure levels assuming "zero" exposure to
asbestos during the time the worker is not involved in asbestos operations and
taking a weighted average over the 8-hour work day.
Since installation, repair, and removal jobs are intermittent, populations
for brake repair and construction have been calculated as full-time
equivalents (FTEs). The FTE population is the number of workers working 250
days/year and 8 hours/day at installing, repairing, and removing the total
quantity of an asbestos product manufactured or imported each year (from the
ICF Market Survey (1986-1987)). In reality, a much larger population would be
exposed for a significantly shorter period of time. FTEs are calculated based
on the average time of a brake job or construction work crew productivity.
Short-term exposures, which represent the exposure during the period of time
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in which the actual task is performed, are applied to this population.
Short-tern exposure levels are converted to 8-hour TWAs (assuming no exposure
to asbestos during the remaining portion of the work day) to project exposures
under the new PEL. Projections are made using the methodology described
below.
c. Proj ected Exposure Levels
Due to the lack of data on engineering controls corresponding to
the current exposure levels, a comparative control evaluation to decide which
controls are effective in achieving exposures of less than 0.2 f/cc and what
exposure levels will actually be reached using these controls is not possible,
Therefore, we used a simplified and conservative approach for projecting
exposure levels under the 0.2 f/cc PEL. This approach assumes that for those
operations where 8-hour TWA exposures are currently below 0.2 f/cc, work
practices will remain unchanged. However, for those operations where the
8-hour TWA exposures are currently above 0.2 f/cc, work practices will be
changed either with the addition of engineering controls or respirators to
reduce the exposures to 0.2 f/cc. It is further assumed that facilities
unable to meet the new PEL would likely cease production or use of asbestos
products. Once the raw data have been manipulated by this methodology, new
geometric and arithmetic mean exposures are calculated; these are the
projected exposures.
In projecting exposures under the new asbestos standard, OSHA (1986b)
generally used a methodology which assumed that current exposure: levels
greater than or equal to 0.2 f/cc would be reduced to 0.15 f/cc, while levels
less than 0.2 f/cc would be reduced to 80 percent of their initial values (in
certain cases, OSHA used a slightly different methodology). We chose not to
adopt OSHA's approach because of the lack of evidence to support these
assumptions, and the unlikelihood that facilities with exposures already belov
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0.2 f/cc would attempt to reduce exposures further with the installation of
expensive engineering controls or the implementation of a mandatory respirator
program. Bragg (1986) states that under the new asbestos standard, industry
will achieve levels of 0.05 f/cc because (1) producers typically aim for
exposures below the PEL to insure compliance and (2) exposures of 0.5 f/cc (or
one-fourth of the PEL) were achievable when the PEL was 2 f/cc. We chose not
to use Bragg's assumption because it becomes more difficult to reduce
exposures below the PEL by such a large margin as the PEL is reduced. We
agree with OSHA and Bragg that producers and users are likely to achieve
exposures below the asbestos standard, and we allow for this by not adjusting
data currently below the 0.2 f/cc. However, for facilities with exposure
levels greater than 0.2 f/cc, the level of reduction possible is not obvious.
Our methodology, therefore, provides conservative estimates of exposure, with
no attempt to "guess" at industry's ability to control exposures below the new
asbestos standard due to the lack of data to support such judgments.
B. Conversion Factor for Asbestos Measurement
In analyzing air releases and ambient exposures, it is necessary to
convert back and forth between f/cc and ng/cc units to allow for dispersion
modeling (requiring mass inputs) and health benefits modeling (requiring fiber
count inputs). This section discusses the phase contrast microscopy (PCM) and
the transmission electron microscopy (TEH) analysis techniques, and the factor
which has been derived to convert measurements from one technique to the
other.
In the PCM technique, the analyst counts the number of fibers (all fibers,
whether or not they are asbestos) larger than 5 urn in length and with an
aspect ratio (length to diameter) of at least 3 to 1. The results are
typically reported as optical fibers/cc. The smallest visible fiber diameter
is approximately 0.2-0.5 urn (Ayer et al. 1965, Chatfield 1983). The choice of
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fiber sizes to be counted was designed to permit optimum reproducibility of
results by different analysts. The PCM method does not differentiate between
asbestos and other fibers; but in most asbestos workplaces, where the only
significant fibrous contaminant is asbestos, this limitation is not very
serious. The size distribution of asbestos fibers, and hence the percentage
of fibers fulfilling the method's counting requirements, is not the same in
all industrial processes or for all types of asbestos. Thus a measurement in
a workplace with a high proportion of small fibers (i.e., fibers with sizes
under the resolution limit of the PCM technique) could be improperly judged to
pose less of a hazard than a measurement in an environment with fewer but
larger fibers (i.e., those which the method would be able to count).
The measurement of asbestos contamination in the ambient air cannot be
adequately performed with PCM. The principal reason for this is that the
proportion of airborne fibers which are actually asbestos in ambient air is
far smaller than that which is found even in "clean" asbestos workplaces, so
that "although it is found that an optical fibre count made on an
environmental sample usually yields a definite value, this value is totally
unrelated to the presence or absence of any asbestos" (Chatfield 1983). The
proportion of total fibers which are asbestos in ambient air has been
estimated to be less than 10 percent (Spumy and Stober 1978). This
difficulty is compounded by the fact that ambient air tends to have a smaller
proportion of the larger, PCM-countable fibers than workplace air (NRC 1984),*
a fact which has also made investigators wary of trying to evaluate the
presence of asbestos in ambient air by a method which only detects the larger
fibers.
* Although there is wide variability, Chatfield (1983) indicates, as an
example, that only 0.7 percent of the total number of fibers in ambient air
exceeded 5 urn in length (i.e., are countable by PCM).
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As a result of these difficulties with the PCM method, ambient levels of
asbestos have been primarily characterized by transmission electron microscopy
(TEM) (Chatfield 1983). With proper attachments,* a transmission electron
microscope can detect all asbestos fibers, of any size, present in air.
Furthermore, since the dimensions of each fiber can be measured, and the
density of each asbestos type is known, the results can be calculated and
reported in mass units (e.g., nanograms or micrograms per m^) or as particle
counts with quite detailed size distributions. Mass concentration is the most
commonly reported parameter.
As discussed above, the PCM method and the TEM method have radically
different resolution characteristics. In effect, if the two methods were to
count the same asbestos cloud simultaneously, they would come up with very
different numbers. It is necessary, therefore, to accurately define a
conversion factor to be able to extrapolate concentrations based on optical
fibers/cc to comparable relationships expressed in the typical TEM units of ug
of asbestos per cubic meter of air (ug/m^) (which are in turn calculated from
TEM counts).
Investigators have attempted to empirically determine such conversion
factors by making parallel measurements with the two methods while adjusting
the TEM technique so that only fibers of the size which would be resolved and
counted by the phase contrast microscope get counted (and their weight
estimated) by the electron microscope analyst. A few such studies have
reported a wide range of conversion factors, and there are at least two
important reasons for the variation in reported values.
The most important reason is quite simple; there is in fact no single
conversion factor, but one for each specific set of conditions. In the words
* Selected Area Electron Diffraction (SAED) and Energy Dispersive X-Ray
Analyzer (EDXA).
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of a recent important review of this issue by the National Research Council
(MC 1984), "these conversion factors usually cannot ... be applied to samples
obtained under a different set of conditions." The conversion factor under
one set of conditions will almost inevitably be different from that obtained
under other conditions (e.g., different process, different source of raw
asbestos) because the size distribution of the airborne asbestos fibers will
be different.
The second important reason for the variability in the conversion factor
is that different methods have been used in different studies to prepare
samples for the transmission electron microscope, and these methods can yield
quite different conversion factors even when other conditions are constant
(Chatfield 1983), Different methods, for example, can result in different
proportions of fibers being lost in sample preparation before counting, or in
significant alterations in the size distribution of fibers from that which
actually exists in the sampled atmosphere (Chatfield 1983).
Despite these uncertainties, there is a measure of scientific consensus
about the appropriate range of values to use as a conversion factor. The most
widely quoted conversion factor of 30 ug/nr per optical fiber/cc has been
reported by Nicholson (EPA 1986g) as the geometric mean (with a very wide
variance) of six studies; the range of conversion factors was 5 to 150. The
National Research Council (NRC 1984) in a recent review cited an equivalent
factor of 30 ug/m-* per optical fiber/cc, based on ratios developed in four
studies, three of which were also included in Nicholson's analysis (EPA
1986g). Another recent review by Conmins (1985) estimates a similar range foi
the conversion factor of 2.5 to 50 ug/m^ per optical fiber/cc, citing eight
references which almost certainly go back to the same original data cited by
the other reviews.
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The range of values reported for the conversion factor (ug/m3 per optical
fiber/cc) fundamentally reflect the true variability of the conditions being
measured and, secondarily, the inherent inaccuracy of the different
measurement methods; The bottom line is that, in effect, there is a "true"
and different factor for each conversion from optical fiber to gravimetric
units, depending on the fiber size distribution of the asbestos cloud in a'
particular situation. There is currently no body of data available, however,
to allow investigators to make elegant estimates of conversion factors under
different circumstances, such as different asbestos processes.
Any single value for a given conversion factor is, therefore, a rough
approximation at best. In this context, we conclude that it is reasonable to
use the reported range of 2.5 to 150 ug/m3 per optical fiber/cc for the needed
conversion factor. An approximate midpoint of 30 ug/m3 per optical fiber/cc
has recently become popularized and is a reasonable value to use; this
conversion is equivalent to 0.03 ng/fiber or 30 fibers/ng.
C. Report Format
This report is divided into two maj or chapters: Occupational Exposure and
Air Releases. Chapter II presents our estimates of occupational exposures
during mining/milling, asbestos product manufacture, chlorine manufacture
using asbestos diaphragm cells, brake repair, and construction. Each
subsection includes a brief discussion of the products included in each
product category, the processes used to manufacture the products or a
description of .the operations, current and projected geometric and arithmetic
mean exposure levels, populations exposed, and duration and frequency of
exposure.
Chapter III presents our estimates of air releases from milling, primary
manufacturing, and secondary manufacturing sources from stacks; and from
mining, brake repair, and construction as area releases. Each subsection
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presents our methodology for estimating air emissions and our emission
estimates.
Appendix A presents geometric and arithmetic mean exposure levels,
population factors, and air emissions for production and use of asbestos
products no longer produced in or imported into the U.S. These data are
reported for use in a sensitivity analysis to estimate likely occupational
exposures and air releases should these products be produced or used in the
U.S. in the future.
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II. OCCUPATIONAL EXPOSURE
This chapter presents our estimates of occupational exposures during
mining/milling, asbestos product manufacture, chlorine manufacture using
asbestos diaphragm cells, brake repair, and construction. Each subsection
includes a brief discussion of the products included in each product category,
the processes used to manufacture the products or a description of the
operations, current and projected exposure levels, populations exposed, and
duration and frequency of exposure.
Due to the lack of data on engineering controls corresponding to the
current exposure levels, a comparative control evaluation to decide which
controls are effective in achieving exposures of less than 0.2 f/cc and what
exposure levels will actually be reached using these controls is not possible.
Therefore, we used a simplified and conservative approach for projecting
exposure levels under the 0.2 f/cc PEL. This approach assumes that for those
operations where 8-hour TWA exposures are currently above 0.2 f/cc, work
practices will be changed either with the addition of engineering controls or
respirators to reduce the exposures to 0.2 f/cc. Once the raw data have been
manipulated by this methodology, new geometric and arithmetic mean exposures
are calculated; these are the projected exposures. Where available,
information on current use of respirators is provided.
The occupational exposure and population data bases from which exposure
estimates for jobs and job categories are derived is limited, often dated, and
contains data gaps and other uncertainties that require the use of
assumptions. Several judgments have been made in the absence of actual data
and these are stated throughout the discussion. Therefore, the results of
this analysis represent estimates given the available data and should be used
cautiously. The exposure estimates, exposed populations, and frequencies and
durations of exposure are by no means absolute values.
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A, Mining and MillinE
1, Process Description
Asbestos fiber is currently mined in the continental United States by
either of two methods. Depending on the type of deposits, asbestos is mined
by open-pit methods using either conventional processes or a hydraulic
processing technique.
Conventional processing methods include blasting, crushing, grinding, and
air classifying the asbestos ore. This mechanism of ore processing is termed
the "dry" method. Alternately, asbestos ore can be mined by the wet process
involving wet screening and grinding. The following sections describe the
mining, crushing and drying, and milling of asbestos ore for each of the two
methods of ore beneficiation. Further details of the processes specific to
each miner/miller are discussed in the exposure sections below.
a. Conventional "Dry" Processing
In the "dry" process, asbestos fiber containing ore is blasted or
drilled from an open-pit bench mine and shovel-loaded into trucks for
transport to the primary and secondary crushing areas at the top of the pit.
The ore is initially crushed at the primary jaw-crusher to reduce the ore
size. The ore is further reduced in size (approximately 3/8-inch in diameter;
at the secondary cone-crusher.
After crushing, the ore is transported by a belt conveyor to the drying
area (rotary and tower kilns). After drying, the ore is transported by
conveyor to the dry ore storage bin. The dried ore is then ready for the
milling operation.
Milling of asbestos fiber-containing ore commences with transport of the
dry ore by conveyor or bottom-dump truck to the milling area. Milling
consists of removing the imbedded asbestos fiber from the ore by a repeated
series of crushing, fiberizing, screening, aspirating, and grading operations
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The ore is introduced into a vibrating screen apparatus where the short
fiber is released from the granular material. The low-density fibers tend to
rise to the top of the screen bed, while the granular material stays on the
screen surface (Kirk-Othmer 1984).
The resultant mixture of rock fragments and asbestos fiber is then passed
over inclined shaking screens to separate the various sizes of material. The
smaller particles of rock and the shorter asbestos fibers pass through the
screen openings and are carried away for further treatment. The coarser rock
fragments and the longer asbestos fibers remain on the screen. The shaking
action of the screen causes the fiber to rise to the top where it is lifted
off by air suction as it nears the end of the screen. The fiber is aspirated
through large air ducts and transported to the collectors (Hwang 1981).
The material remaining on the screen, which consists mainly of unfreed
asbestos in rock fragments, passes to fiberizers that release the rest of the
fiber.
The coarse material that has fallen through the initial screening is
rescreened and refiberized using finer mesh screens to recover medium and
shorter length fibers.
Finally all of the fibers are cleaned and separated into various
commercial grades and bagged in woven polylaminate or paper bags for shipment.
Packing of finished fibers is usually done by loose- or pressure-packing
machines ("baggers") that consolidate the fibrous material into the bag (NIOSH
1982a).
In pressure packing the fiber is transported from a bin by screw conveyors
to pressure packers preceded by precompressors and pre-weighers (all
operations are automatically controlled). Loose-packing requires only ambient
pressure and no compression of the fibers.
- 25 -
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b. Unconventional "Wet" Processing
The recovery of milled asbestos fiber from ore is usually quite lo
(about five percent). The New Idria mining district, however, contains a
unique asbestos deposit that is an agglomerated ore consisting of more than 5
percent asbestos with moisture content of up to 20 percent. The deposit is
made up of soft, friable sheets and clumps of asbestos fiber that consist
mainly of very short chrysotile fibers.
The asbestos ore is mined by a conventional open pit method. After
scraping off 10 to 20 feet of overburden, bulldozers and scrapers are used to
remove the ore from the deposit (Myers 1986a). The ore is loaded into bottom
dump trailers though a 3/8-inch screen and hauled about 60 miles to the mill
site, where it is stockpiled. Asbestos ore stored at the mill stockpile is
periodically watered down to prevent fibers from becoming airborne.
Ore from the stockpile at the mill is slurried, crushed, sized, screened,
dewatered, pelletized, and dried. A portion of the product is sold in pellet
form and is shipped by bulk or in bags. The remaining pellets are further
processed through a hammer mill to produce open fibers that are packaged and
bagged in the conventional manner (NIOSH 1982a).
c- Exposure Controls
Typically, the emissions from asbestos mining and milling opera-
tions are kept to a minimum by the use of fairly simple process controls. Ai
releases of asbestos fibers encountered during mining activities are
controlled by wetting the ore and fiber deposits. Due to the outdoor nature
of mining, it is difficult to use any type of process controls or filtering
systems other than personal air-filtering devices (Myers 1986a, Toney 1986) t
control airborne asbestos levels.
Protective factors represent the "minimum anticipated workplace level of
respiratory protection that would be provided by a properly functioning
- 26 -
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respirator or class of respirators to a percentage of properly fitted and
trained users" (Myers n.d.). There are possible complications associated with
using protective factors. The protective factors are for the ideal scenario
and do not take into account elements that would reduce the protective ability
of the various respirators and masks. The protective devices must be worn
properly and cleaned regularly to insure that they are working correctly.
They must fit well and movement must be kept to a minimum (Rosenthal and Paull
1985). The Chemical Engineering Branch of the Office of Toxic Substances at
EPA recommends a protection factor of 10X for any air-purifying half-mask
respirator including disposable equipped with any type of particulate filter
except single use, any air-purifying full facepiece respirator equipped with
any type of particulate fitter, or any supplied air respirator equipped with a
half-mask and operated in demand (negative pressure) mode (Myers n.d.). A
protection factor of 25X is recommended for any powered air-purifying
respirator equipped with a hood or helmet and any type of particulate filter,
or any supplied air respirator equipped with a hood or helmet and operated in
a continuous flow mode (Myers n.d.). These recommendations are based on
examination of literature and various experts in government and industry.
These protection factors are conservative estimates of actual protection which
is difficult to predict. The actual protection factors are not less than the
recommended factors, but may be greater than* the recommended factors for these
types of respirators (Myers n.d.).
Milling activities are such that airborne asbestos levels can in some
cases be controlled. Many processing areas are enclosed and many operations
are automated. These measures significantly reduce the exposure level that
workers would encounter, but cannot be used in all process areas. Local
exhaust ventilation and air filtering systems (e.g., baghouses) reduce
airborne fiber levels in the workplace and help to minimize exposure during
- 27 -
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milling activities. The baghouse is also an efficient means of recycling
fiber to the milling operation, thereby increasing the efficiency of the
process and reducing the amount of waste that must ultimately be disposed.
During some milling activities, airborne fiber levels can be reduced by
wetting the fiber, but this technique is limited to those processing
techniques where moisture is permissible (e.g., in "wet" processing prior to
the drying operation and in conventional processing prior to kiln drying and
screening).
The most efficient method of controlling airborne fiber levels, as in th«
case of mining, is by the use of respirators. Other systems, if they are
employed, are an additional method of controlling fiber levels, but do not
insure that workplace fiber levels meet the required MSHA standard (2 f/cc)
for mining and milling activities.
2. Manufacturers and Production
The three domestic producers of asbestos fiber are located in
California (2 companies) and Vermont (1 company). The mines, their location,
and the annual production of asbestos fiber are listed in Table 4. The volui
of domestic asbestos fiber production has decreased steadily over the years.
Current production levels are about one-third of 1980 levels, but are consi-
dered to be at a static level; production should remain at 1986 levels for
1987 and beyond until new regulations or use restrictions are proposed and
implemented.
3. Current Exposures
The current standard for occupational exposure during mining and
milling activities is 2 fibers per cubic centimeter (f/cc) as set by the
Department of Labor, Mine Safety and Health Administration (MSHA). The
standard (0.2 f/cc) that has been set by the Occupational Safety and Health
Administration (OSHA) does not apply to mining and milling activities because
- 28 -
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Table 4. Annual Domestic Production of Asbestos Fiber for 1985
Annual Production
Mine and Location Volume (tons)
Calaveras Asbestos, Ltd. 34,000
Copperopolis Mine
Calaveras County, CA
KCAC Incorporated 20,000
Joe 5 Pit
San Benito County, CA
Vermont Asbestos Group 8,070
Lowell Mine
Orleans County, VT •
Total 62,070
Sources: Myers 1985, Kenmer and Hall 1986,
Phelps 1987.
- 29 -
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OSHA has no jurisdiction in these areas. The exposure data presented herein
allows for comparison with exposures from other activities over which OSHA
does have jurisdiction.
MSHA publishes personal exposure data for various mining and milling
activities, including asbestos. Additional exposure data for one of the
asbestos mining and milling facilities (Calaveras Asbestos Ltd..) have been
provided by a contact at that facility (Toney 1987). Data from this source
are also analyzed.
The MSHA personal exposure data for each mining and/or milling site are
broken down by labor category, and the asbestos exposure concentrations are
presented in f/cc. All exposures of interest are shift weighted averages
(8-hour time-weighted average (TWA)).
The procedure used to determine the presence of asbestos fibers is a
modification of a standard asbestos fiber counting method (NIOSH Standard
#582). The modified procedure initially employs phase contrast microscopy
(400-450X magnification) to verify the presence of fibers. If two or more
fibers are detected per cubic centimeter, the sample is stained with a
solution to determine if the fibers initially detected are asbestos fibers.
This technique, known as staining dispersion, tests positive in the presence
of asbestos. If the results are positive, the sample is examined under the
electron microscope to determine the aspect ratio of the fibers. The
analytical and sampling procedures are not 100 percent reliable; and,
therefore, an error factor is taken into account in determining whether to
issue a citation for exposure samples that are shown to contain asbestos
fibers in concentrations greater than the exposure limit. All MSHA personal
exposure data presented for the asbestos mining and milling facilities are foi
filter-type samples (Autio 1986).
- 30 -
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To assess the magnitude of possible exposure at each site, an
understanding of the processing techniques employed is necessary. Therefore,
a brief discussion of each mining and milling facility, its practices, and its
engineering controls (if available) is presented below. These discussions are
accompanied by a detailed description of the job categories and exposure data
for each site. The exposure data are first presented as airborne breathing
zone samples for each site. The exposure data are then adjusted using the
respirator protection factor for those job categories for which respiratory
equipment is designated as mandatory by each facility; this adjusted exposure
is the level to which the worker is actually exposed.
a. KCAC Incorporated
The mine operations used by KCAC Inc. are conventional open-pit
stripping methods. There is no drilling or blasting; and as the ore contains
up to 20 percent moisture, emissions are minimal (Myers 1986a). The stripping
and scraping operations are only undertaken about every three years (other
mining operations are performed annually, seven months per year), and the ore
is stockpiled at the mine for subsequent screening and hauling to the mill.
The work areas at the mine are wetted as necessary with water trucks during
stripping, screening, and truck loading to keep asbestos fibers from becoming
airborne. The mine operates eight hours/day and four days/week for the dry
months of April through October (Myers 1986a).
KCAC Incorporated employs three people at their Joe 5 Pit mining facility.
The three employees at the mine site can be designated as two production
workers and one supervisor (Myers 1986b). The tasks that are undertaken at
the mine fall into six MSHA Job Code categories according to the personal
exposure data. The job categories and exposure levels for the Joe 5 Pit area
are given in Table 5. When multiple exposure samples are available, geometric
and arithmetic means have been calculated.
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Table S. Asbestos Exposure Profile for the Mining and Milling Operations at KCAC Incorporated
Job Category (MBHA Job Code)
Mining
Scraper/Loader Operator (682)
Front-End Loader Operator (762)
Bulldozer Operator (368)
Dry Screening Plant Operator (488)
Scalper/Screener Operator (388)
Dryer Operator (379)
Number of
Workers"
N/A
H/A
N/A
N/A
N/A
H/A
Current Exposure Level
Without Respiratory Protection
(f/cc)b
Geometric Mean
0.
0.
0.
0.
0.
Oj
39
26
45
80
62
63
(2)
(2)
(3)
(1)
(1)
(1)
Arithmetic Mean
0.44
0.34
0.59
0.80
0.62
Ml
Current Exposure Level
With Respiratory Protection
(f/cc)d
Geometric Mean
0.039
0.026
0.045
0.080
0.062
0.063
Arithmetic Mean Frequency
0.044
0.034
0.059
0.080
0.062
0.043
8 hr/d.
8 hr/d.
8 hr/d,
8 hr/d.
8 hr/d,
8 hr/d,
4
4
4
4
4
4
and Duration
d/wk,
d/Mk,
d/wk.
d/wk.
d/wk.
d/wk,
7 mo/yr
7 mo/yr
7 mo/yr
7 mo/yr
7 mo/yr
7 mo/yr
Total Number of Workers Involved
in Mining Operations
Weighted Average Exposure Level
for Mining Operations0
0.33
0.57
0.053
Total Number of Workers Involved
in Milling Operations
Weighted Average Exposure Level
for Milling Operations*
30
0.41
0.43
0.041
0.057
Milling.
Front -End Loader Operator (782)
Bulldoter Operator (368)
Slurry, Mixing, Pumping Operator (379)
Concentrator Operator (679)
Ball, Rod, or Pebble Mill Operator (179)
Palletizing Operations Worker (779)
Dryer Operator (379)
Bagging or Packaging Operations Worker (879)
Forkllft Operator (389)
Maintenance (618)
2
1
2
4
N/A
2
2
4
4
_2_
0
0
0
0
0
0
0
0
0
p
.21
.86
.39
.20
.50
.51
.49
.36
.29
• 9?
(3)
(1)
(1)
(1)
(1)
(2)
(3)
(10)
(3)
(1)
0.22
0.86
0.39
0.20
0.30
0.51
0.49
0.51
0.36
JLS
0.021
0.086
0.039
0.020
0.050
0.051
0.049
0.036
0.029
0.052
0.022
0.086
0.039
0.020
0.050
0.051
0.049
0.051
0.036
0.052 1
hr/d,
hr/d,
hr/d.
hr/d,
hr/d.
hr/d,
hr/d,
hr/d,
hr/d,
J hr/d.
3
3
3
5
3
5
3
3
5
3
d/wk.
d/wk,
d/wk,
d/wk.
d/wk,
d/wk.
d/wk.
d/wk,
d/wk,
d/wk,
12 mo/yr
12 mo/yr
12 mo/yr
12 mo/yr
12 mo/yr
12 mo/yr
12 mo/yr
12 mo/yr
12 mo/yr
12 mo/yr
0.043
N/A - Not available.
"Myers 1986b.
bMSHA 1986. Exposure levels are geometric and arithmetic mean, 8-hour TWA*. The number of data points is given in parentheses.
cAssumes all employees spend equal time performing each job and are, therefore, all exposed to the same average exposure level.
-------
Table 5 (Continued)
Assumes all employees use full-face mask respirators with a protective factor of 10X (Myers 1986b, Myers n.d.).
aThe average Is calculated by weighting exposure values by number of employees in each category. In categories for which no data on nunfeer of employees
are available, exposure values are excluded from the average exposure.
-------
HSHA designates six job categories for the mining operations of KCAC
Incorporated, while KCAC registers only 3 employees for that site. It is,
therefore, obvious that some of the jobs are only operational for a portion of
the shift. For purposes of this analysis, we assume that the 3 employees are
involved in each of the jobs for equal amounts of time during each shift.
After screening at the mine site, the asbestos containing ore (3/8-inch
pieces and less) is transported about 60 miles to the King City Mill in
Monterey County. Prior to milling, the ore is stockpiled about 1/4-mile from
the mill and is kept wet with water trucks and sprinkler systems as necessary
to reduce emissions (Myers 1986a).
The milling process utilized by KCAC is the "wet" method and involves
slurry ing the ore (about 90 percent asbestos) with water and pumping it to the
mill (Myers 1985). The ore beneficiation system is wet until the final drying
and packaging operations, which are all equipped with baghouse-type dust
collection systems. Collected dust is either directly sent to a product bin
or slurried with water and returned to the process. The King City Mill is
operational eight hours/day and five days/week for the full year.
The KCAC King City Mill has 43 employees involved in various activities.
However, not all of these employees are involved in the production of
asbestos. The breakdown of asbestos production workers by job category is
approximately as follows (Myers 1986b):
9 - Maintenance employees
4 - Forklift operators
4 - Concentrator operators
4 - Bagging and packaging (includes RG-244 and wet-end)
2 - Slurry/pumping/mixing operators
2 - Dryer operators
2 - Pelletizing operators
2 - Front-end loader operators
1 - Bulldozer operator
30 Production Workers and Supervisors
- 34 -
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The exposure data from MSHA does not cover all of the categories identified by
KCAC, but weighted average exposure levels for the available categories based
on the number of exposed workers are presented in Table 5. All of the data
presented in Table 5 are personal exposure data, eight-hour time weighted
averages.
It should be noted that 80 percent of all personnel at both KCAC
facilities (mine and mill) wear full-face respirators depending on the
particular activities in which they are involved (Myers 1986b). Respirators
are required in certain areas and while performing certain activities (e.g.,
packaging and loading operations), but are not mandatory in all areas (Myers
1987). It is assumed, however, that all workers are wearing respirators at
all times until more exact information becomes available from KCAC Inc. Using
this assumption, actual exposure accounting for use of respiratory protection
would be 10X (Myers n.d.) less than that indicated by the MSHA personal
exposure data.
b. Calaveras Asbestos. Ltd.
The mining and milling operations of Calaveras Asbestos, Ltd. are
located at the same facility in Copperopolis, California. The operations are
seasonal (10 months/year); the mine and mill are closed in January and
February. Due to the seasonal nature of the operation at Calaveras Asbestos'
facility, the number of production workers varies. During active periods, the
mine is in operation for eight hours/day and five days/week, while the mill is
in operation 24 hours/day and five days/week (Toney 1986) . •
The mining operation at Copperopolis is a conventional open-pit bench
mine. Ore is blasted or drilled and then loaded into trucks and hauled to the
primary and secondary crusher area at the top of the pit. After the ore has
been crushed (jaw, cone, and impact crushers), it is transported by conveyor
to the drying area. After drying, the ore is transported, again by conveyor,
- 35 -
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to the dry ore storage bin for holding until needed for the milling operation:
(NIOSH 1982a).
Calaveras Asbestos, Ltd. produces asbestos grades from their milling
operations that can be classified as Group 4 (1/8-inch long) and Group 6 (3/8-
inch long) fibers. To produce these fibers, the ore is beneficiated by
crushing, screening, and fiberizing the various sizes of asbestos-containing
ore. Finally, the asbestos fibers that reach the top of each shaking screen
are vacuumed off, sent to the collector, separated by fiber size, cleaned, and
bagged in woven polylaminate or paper 100-pound bags for shipment. Bagging or
packaging is performed by a hydraulic pressure packer (NIOSH 1982a).
The average number of workers at Calaveras Asbestos is 135 or more (Toney
1986). Not all of these workers, however, are involved in the production of
asbestos fiber from ore. Depending on the time of year and whether the mill
is operating at full or partial capacity, the actual number of workers exposed
to asbestos in the mining and milling operations is about 80 (Toney 1987).*
A breakdown of production workers by job category is presented in Table 6.
The number of workers and exposure data by job category are provided for
mining and milling activities, as well as exposure reduction achieved by the
use of air-purifying equipment. Both MSHA and Calaveras (Toney 1987)
monitoring data are used to estimate geometric and arithmetic mean exposures
by job category. The Calaveras Asbestos samples are taken as part of an
on-going monitoring program (Toney 1987).**
It should be noted that conventional mining and milling operations are
more labor intensive than "wet" processing operations due to considerations
involving the nature of the ore recovery and beneficiation methods and the
relative age and inefficiency of the equipment used in the conventional
operations.
** Mining exposure data provided by Calaveras Asbestos, Ltd., are from
samples taken in the spring months when atmospheric conditions cause the
exposure levels to be less than in summer months. The exposure values can be
expected to be 50-75 percent higher in the summer months than the actual
values for mining activities obtained in April (Toney 1987).
- 36 -
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Table 6. Asbestos Exposure Profile for the Mining and Milling Operations at Calaveras Asbestos, Ltd.
Job Category (MSBA Job Code)
Mining
Powdergang Worker* (607)
Churn Drill Operator* (434)
Front-End Loader (762)
Quarry Truck Driver (376)
Bulldozer Operator (368)
Dunp Operator (622)
Hater Truck/Blade Operator (479)
Supervisor (649)
Greaser/Oiler (618)
Number of
Workers"
3
2
2
11
2
1
1
2
_i
Current Exposure Level
Without Respiratory Protection
(f/cc)B
Geometric Mean
0.08
0.12
0.07
0.02
0.11
0.11
0.10
N/A
0.18
(1)
(2)
(1)
(1)
(1)
(1)
(2)
(2)
Arithmetic Mean
0.08
0.13
0.07
0.02
0.11
0.11
0.11
N/A
0.13
Current Exposure Level
With Respiratory Protection
(f/cc)d
Geometric Mean
0.008
0.012
0.007
0.002
0.011
0.011
0.010
N/A
0.012
Arithmetic Mean Frequency
0.008
0.013
0.007
0.002
0.011
0.011
0.011
N/A
0.013
6
8
8
8
8
8
8
8
8
hr/d.
hr/d.
hr/d,
hr/d.
hr/d,
hr/d,
hr/d.
hr/d,
hr/d,
5
3
3
3
5
5
5
5
5
and Duration
d/wk,
d/«*,
d/wk,
d/wk.
d/wk,
d/wk.
d/wk,
d/wk,
d/wk,
10/mo/yr
10/Do/yr
10/mo/yr
10/mo/yr
10/mo/yr
10/mo/yr
10/mo/yr
10/mo/yr
10/mo/yr
Total Number of Workers Involved in
Mining Operations
Weighted Average Exposure Level
for Mining Operations0
25
0.06°
0.06*
0.006
Total Number of Worker* Involved
In Milling Activities
Weighted Average Exposure Level for Milling
Operation*6
49
0.39
0.49
0.034
0.006
Hilling
Front End Loader Operator (782)
Gathering Arm Loader Operator (043)
Mill Operators (179)
Crusher Operators (079)
Sizing and Hashing Operation* Workers (388)
Dryer Operator* (379)
Bagging or Packaging Operation* Worker* (879)
Forklift Operators (389)
Janitor* (413)
Laboratory Technician* (314)
1
1
3
4
3
2
19
7
3
6
0.34
0.30
0.41
0.48
0.69
2.14
0.26
0.14
0.57
o,??
(2)
(1)
(1)
(5)
r (5)
f (1)
(14)
(3)
(5)
(2)
0.33
0.30
0.41
0.73
0.70
2.14£
0.40
0.24
0.65
0.25
0
0
0
0
0
0
0
0
0
0
.034
.030
.041
.048
.069
.086
.026
.014
.057
^025
0
0
0
0
0
0
0
0
0
o
.033
.030
.041
.073
.070
.086
.040
.024
.063
,025
hr/d,
hr/d,
hr/d,
hr/d.
hr/d,
hr/d.
hr/d.
hr/d,
hr/d,
hr/d,
3 d/wk,
3 d/wk,
5 d/wk,
5 d/wk,
3 d/wk.
5 d/wk,
3 d/wk.
3 d/wk,
3 d/wk,
5 d/wk,
10 mo/yr
10 mo/yr
10 mo/yr
10 mo/yr
10 mo/yr
10 mo/yr
10 mo/yr
10 mo/yr
10 mo/yr
10 mo/yr
0.044
N/A - Not available.
*Toney 1987.
TCHA 1986, Toney 1987. Exposure level* are geometric and arithmetic mean, 6-hour TWA*. MSHA job code* are assigned to the job titles used in the
Calaveras exposure data summary. The number of data points is given in parentheses.
-------
Table 6 (Continued)
cTh» average le calculated by weighting exposure values by number of employees in each Job category. Categories for which no data on number of employees
ot exposure levels ate available are excluded from the exposure analysis.
Assumes all mine employees use a half-face mask with a protective factor of 10X and all mill employees use half-face masks (protection factor of 10X)
except dryer operator* who use battery powered helmets (protection factor of 25X) (Toney 1987, Myers n.d.).
elt should be noted that the average value for exposure during mining operations is low for the Calaveras site. This la due in part to the large number
of truck drivers responsible for ore-hauling at the facility. There la a high demand for ore-hauling because ot the low asbestos content of the ore, and
the truck driver exposure is comparatively low.
MSHA data for this job category indicated an 8-hour TWA exposure of 0.04 f/cc. This data point has not been included in this analysis because Calaveras
Asbestos, Ltd. (Toney 1987) Indicated that exposure for these workers is usually high. Calaveras requires a battery powered helmet for workers in this
category due to the high concentrations of asbestos that they encounter.
00
I
-------
The 25 workers involved in the mining of asbestos-containing ore can be
divided approximately as follows (Toney 1987):
11 - Quarry Truck Drivers
3 - Powder Gang (1 powderman, 2 helpers)
2 - Front-End Loader Operators
2 - Supervisors
2 - Bulldozer Operators
2 - Drill Operators
1 - Greaser/Oiler
1 - Dump Operator
1 - Hydration Plant (Water Truck/Blade) Operator
25 Production Workers and Supervisors
In addition to the employees involved in mining activities at Calaveras
Asbestos, there are 49 employees involved in milling activities at the same
site. The breakdown of workers for milling is approximately as follows (Toney
1987):
19 - Bagging or Packaging Operations Workers
7 - Forklift Operators
6 - Laboratory Technicians
4 - Crusher Operators
3 - Sizing and Washing Operations Workers
3 - Janitors
3 - Mill Operators
2 - Dryer Operators
1 - Gathering Arm Loading Operator
1 - Front-End Loader Operator
49 Production Workers and Supervisors
Maintenance workers are intimately involved in the production of asbestos
fiber, but are not classified as either miners or millers. Maintenance
workers could be included within the category where their job is performed
(e.g., screen repairman could be included with mill workers), but Calaveras
Asbestos, Ltd. claims that these workers are usually excluded from exposure
studies dealing with mining and/or milling due to the intermittent and varying
nature of the exposure that occurs in these occupations (Toney 1987).
It is likely that maintenance employees will be engaged in activities that
will cause them to be exposed to high levels of asbestos. For example, a
- 39 -
-------
mechanic may be exposed to high asbestos fiber concentrations while repairing
drilling equipment or overhauling bagging or packaging equipment used in the
milling operations. It is not likely, however, that maintenance employees
will be exposed to high levels of asbestos for extended periods of time.
Maintenance operations are of a changing nature, and there are two factors
that would affect the level and duration of actual maintenance exposure:
(1) The employee may be a skilled laborer (e.g., mechanic)
and may be exposed to asbestos for only short periods
(i.e., less than eight hours per shift); and
(2) The employee may have varying maintenance duties and may
be exposed to very different levels of airborne asbestos
fibers depending on activities at a given time during the
shift.
It is, therefore, difficult to develop "average" eight-hour TWA exposure
levels for maintenance workers due to the probable fluctuation in exposure
levels and the transitory nature of the activities.
The job categories identified as being part of the maintenance operations
include:
clean-up crew workers;
laborers/bullgang;
screen repairmen;
supply handlers;
mechanics;
engineer/technical services; and
building repair crew.
It should be noted that maintenance workers are normally associated with the
mining and milling of asbestos, but their duties are considered by Calaveras
Asbestos to be independent of the actual mining and milling operations (Toney
1987). While it is true that the equipment used and the facilities employed
in the production of asbestos fiber from ore need to be maintained, these
activities are not specifically a part of the mining or milling operations.
Available HSHA and Calaveras exposure data for maintenance workers are,
therefore, not presented herein.
- 40 -
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The other asbestos mining sites and milling facilities (KCAC, Inc. and
Vermont Asbestos Group) have specified that maintenance operations should not
be considered separately from mining and milling operations; and, therefore,
exposure data for maintenance workers have been included in the relevant
operation (mining or milling) for those sites (Hyers 1987, Phelps 1987).
All mining and milling workers at Calaveras required by MSHA to wear
protective devices do so. In addition, many workers that are not required to
wear air-purifying and air-filtering equipment wear them due to health
concerns. There are two types of protective devices worn by employees at
Calaveras Asbestos:
• negative-pressure, HEPA filter, half mask, self-contained
breathing apparatus; and
• 3M(R) model number W-344, battery powered helmets with a
3M(R)-8710 disposable face plate.
The negative-pressure, half masks have a protective factor of 10X and are worn
by all employees exposed to asbestos, with the exception of those potentially
exposed to fiber concentrations greater that 2 f/cc (Toney 1987, Myers n.d.).
There is at least one job (dryer operator) that would potentially expose
workers to asbestos levels greater than 2 f/cc. All employees in this
exposure category are required to wear the battery powered respirators that
have been recommended for a protection factor of 25X (Toney 1987, Myers n.d.).
Calaveras will be equipping workers in higher exposure categories with a more
efficient respirator in 1987; this model is a full face, HEPA filtered,
battery powered respirator with a nose clip. These respirators have been
approved for a protective factor of SOX in the workplace environment and the
amount of protection provided is not affected by variation in fit or movement
(Toney 1987, Myers n.d.).
A breakdown of the number and type of employees that actually wear some
type of protective equipment is not available. Therefore, it will be assumed
- 41 -
-------
that all employees except those identified as wearing more efficient
respirators (protection factor of 25X), are wearing half-face masks that have
a protective factor of 10X (Myers n.d.).
c. Vermont Asbestos Group
The mining and milling operations at the Vermont Asbestos Group
(VAG) are of the conventional type and are very similar to the operations at
the Calaveras Asbestos facility. The VAG facility (the Lowell mine and mill)
is located in Orleans County, Vermont and employs 75 people, 48 that were
involved in some aspect of the production of asbestos fiber from asbestos -
containing ore in 1985. The number of production workers and supervisors was
also about 50 in 1986 and is expected to remain the same in 1987 (Phelps
1987).
Previously, the Lowell mine and mill has employed more production workers
while operating at full capacity (35,000 tons of fiber per year). Currently,
it is operating at about 1/4 capacity, producing 8,070 tons of asbestos fiber
in 1985 and roughly the same amount (less than 10,000 tons) in 1986 (Phelps
1987).
There are two shifts per day at the VAG mining facility. Most of the
operations at the mine are performed during the first shift. Most operations
last eight hours/day and 186 days/year, although conveyor belt crew operators
work ten hours per shift. The second shift at the mining site is a skeleton
crew of three (truck drivers and one shovel operator) that are responsible for
hauling ore to the milling facility (Phelps 1987). Milling operations are
also performed for 186 days per year, but there is only one shift per day.
The shifts are ten hours each, except for four activities (lab technician,
supply handler, backhoe operator, and some supervisors) that are performed on
eight-hour shifts.
- 42 -
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There are approximately 16 mine workers involved in various activities at
the Lowell mine that can be divided into various job categories. An
approximate breakdown of workers for mining activities as provided by VAG
(Phelps 1987) is:
6 - Conveyor Belt Crew Workers
2 - Rotary Drill Operators
2 - Quarry Truck Drivers
2 - Bulldozer Operators
2 - Drill Helpers
1 - Front-End Loader Operator
1 - Shovel Operator
16 Production Workers and Supervisors
The number of workers involved in milling activities at VAG is 32 and can be
divided as follows (Phelps 1987):
8 - Maintenance Workers
6 - Bagging or Packaging Operations Workers
5 - Clean-up Crew Workers
3 - Laboratory Technicians
3 - Administrative Supervisors
2 - Dryer Operators
2 - Crusher Operators
1 - Dry Screening Plant Operator
1 - Supply Handler
1 - Backhoe Operator
32 Production Workers and Supervisors
MSHA personal exposure data are available for various activities
undertaken at the VAG facility (Table 7). The breakdown of employees by job
category provided by VAG (Phelps 1987) is used to determine weighted exposure
values for mining and milling activities.
No separation of maintenance workers has been performed because these
workers are considered part of the milling activities for VAG (Phelps 1987).
In addition, no breakdown of maintenance workers by specific activity (e.g.,
mechanic, welder) was available. For some job categories provided by VAG,
there are no exposure levels available from MSHA; these job categories have,
therefore, not been included in the weighted-average exposure calculations.
- 43 -
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Table 7. Asbestos Exposure Profila for th* Mining and Milling Operations at the Vermont Asbestos Group
Number of
Job Category (MSBA Job Code) Workers"
Mining
Rotary Drill Operators (734 and 634)
Drill Helper (833)
Bulldozer Operator (368)
Conveyor Belt Crew (601)
Front-End Loader Operator (782)
Shovel Operator (367)
Truck Driver (376)
Total Number of Workers Involved in
Mining Operations
Weighted Average Exposure Level for Mining
Operations0
Hilling
Backhoe Operator (778)
Crusher Operator (079)
Dry Screening Plant Operator (488)
Dryer Operator (379)
Bagging or Packaging Operations Worker (879)
Clean-Up Man (613)
Administrative Supervisor (649)
Supply Handler (671)
Maintenance (513)
Laboratory Technician (514)
Total Number of Worker* Involved in
Milling Operations
2
2
2
6
1
1
_2
16
1
2
1
2
6
5
3
1
a
3
32
Current Exposure Level
Without Respiratory Protection
(f/cc)b
Geometric Mean
0.58
0.16
0.70
0.38
0.27
N/A
N/A
0.42
N/A
0.49
0.59
0.58
0.63
1.74
1.14
N/A
N/A
0,63
(3)
(1)
(2)
(3)
(2)
(6)
(13)
(5)
(10)
(13)
(1)
(1)
Arithmetic Mean
0.59
0.16
0.98
0.54
0.34
N/A
N/A
0.54
N/A
0.51
0.66
0.66
0.67
2.31
1.14
H/A
R/A
0.63
Current Exposure Level
With Respiratory Protection
(f/cc)d
Geometric Mean
0.058
0.016
0.070
0.038
0.027
N/A
N/A
0.042
N/A
0.049
0.059
0.058
0.063
0.174
0.114
N/A
N/A
0.063
Arithmetic Mean Frequency and Duration
0.059
0.016
0.098
0.054
0.034
N/A
H/A
0.054
H/A
0.051
0.066
0.066
0.067
0.231
0.114
H/A
R/A
0.063
. 8
8
8
10
8
a
8
8
10
10
10
10
10
10
8
10
10
hr/d,
hr'/d,
hr/d,
hr/d,
hr/d.
hr/d,
hr/d.
hr/d.
hr/d.
hr/d,
hr/d,
hr/d.
hr/d,
hr/d.
hr/d,
hr/d,
hr/d,
186
186
186
186
186
186
186
186
186
186
186
186
186
186
186
186
186
d/yr
d/yr
d/yr
d/yr
d/yr
d/yr
d/yr
d/yr
d/yr
d/yr
d/yr
d/yr
d/yr
d/yr
d/yr
d/yr
d/yr
Weighted Average Exposure Level for Milling
Operations0
0.93
1.09
0.093
0.109
N/A - Not available.
•Phelpa 1987.
HcHA 1986. Exposure levels are geometric and arithmetic mean, 8-hour THAI. The number of data points is given in parentheses.
°The average la calculated by weighting exposure values by number of employees in each Job category. Job categories for which no data on number at
employees or exposure levels are available are excluded from the exposure analysis.
dAssumes all employees use half-face masks with a protection factor of 10X.
-------
All employees at VAG are required to have a respirator (Gerson disposable
Number 1710) with them at all times, and these respirators must be worn in
specified areas of the facilities as part of a mandatory respirator program
(ICF Exposure Survey 1986-1987). The Gerson Number 1710 has a workplace
protection factor of 10X, but labelling for use with asbestos has been
voluntarily removed by the company at the request of NIOSH (Bellinger 1987).
While MSHA is not bound by law to follow NIOSH criteria and recommendations
for asbestos, VAG may wish to follow NIOSH recommendations and require some
other type of respirator. For preliminary calculations, we have assumed that
the Gerson masks provide a protective factor of 10X, although it may be more
appropriate to use a lower protective factor for this type of respirator.
The only type of exposure controls in place are negative draft from
baghouses located at various emission sources throughout the plant (ICF
Exposure Survey 1986-1987).
4. Summary
Available data make it possible to break down the exposure for mining
and milling activities by job category. The number of employees in each job
category for each facility and their respective 8-hour TWA exposure levels and
exposure duration/frequency are presented in Tables 5, 6, and 7.
An overall profile of asbestos exposures in the mining and milling
industries for each facility, taking into account information on number of
workers by job category and protective equipment used, show that average
exposure levels are well within the MSHA permitted exposure, limit of 2 f/cc,
and with protective devices provided by the facilites (required in some
instances) could be well below the OSHA standard (0.2 f/cc).
B. Product Manufacture
This section presents occupational exposure profiles for primary and
secondary product manufacture. For product manufacture, a large quantity of
- 45 -
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exposure monitoring data are available. Both geometric and arithmetic means
of the raw exposure data are presented in this section. The raw exposure data
have been converted based on each worker's duration of exposure such that the
effective duration of exposure is 8 hours/day.
Due to the limited availability of exposure data on any one product, we
have estimated exposure levels for product categories. However, these product
category exposures are applied to the worker populations for eac.h individual
product (from the 1CF Market Survey 1986-1987), thus allowing for some
distribution of risk by product. This analysis, however, assumes that job
category exposures from all products in a product category are identical. The
product categories are:
Paper products;
Asbestos cement products;
Friction products;
Textiles;
Packings and gaskets;
Coatings;
Asbestos-reinforced plastics; and
Miscellaneous uses.
This analysis does not cover products no longer produced in the U.S. or
imported into the U.S. such as commercial paper, corrugated paper, rollboard,
flooring felt, roofing felt (imported only), corrugated A/C sheet (imported
only), and vinyl asbestos floor tile. Occupational exposure levels and
population factors for products no longer produced or used in the U.S. are
i
presented in Appendix A for use in sensitivity analysis.
To distribute total populations froa the IGF Market Study (1986-1987) into
job categories, 1981 TSCA Section 8(a) data were used (Hendrickson and Doria
1983, EPA n.d.). The percent of the total worker population in each job
category for each product in 1981 was assumed to be the same in 1985. This
percentage was applied to the 1985 total population to estimate the number of
workers in each job category. Since job categories defined in this report do
- 46 -
-------
not always correspond to those presented in the TSCA Section 8(a) data, it was
often necessary to attribute the percent population from the 8 (a) data evenly
among two or more of our job categories.
1. Paper Products
a. Product Descriptions
Asbestos is used in papers primarily due to its chemical and heat
resistant properties. This section provides descriptions of those asbestos
paper products currently manufactured in the U.S. and/or imported for
secondary manufacture or installation in the U.S. These products include
millboard, roofing felt (imported only), pipeline wrap, beater-add gaskets,
high-grade electrical paper, and specialty papers. Currently, rollboard,
corrugated paper, commercial paper, and flooring felt are no longer
manufactured in the U.S. nor are they imported (IGF Market Survey 1986-1987).
Sources indicate that no roofing felt is produced in the U.S.; however,
283,200 squares of roofing felt are imported annually (ICF Market Survey
1986-1987). Nevertheless, there are no production workers exposed to asbestos
roofing felt; thus, it is excluded from this section.
(1) Millboard
Asbestos millboard is an asbestos paper product similar in
appearance to heavy cardboard. It is used as a fire-resistant lining in
floors, walls, ceilings, and fire doors, as well as an insulating barrier in
commercial ovens and household appliances. Different grades of millboard are
available, each differing in their ability to withstand elevated temperatures.
Standard millboard may withstand temperatures up to 850*F high quality
millboard may withstand up to 1,000'F. Certain "premium" grade asbestos
millboards are manufactured to withstand temperatures well above 2,000°F.
The primary constituent of asbestos millboard is asbestos fiber, with the
balance consisting of binders and fillers. The asbestos content ranges from
- 47 -
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60 to 95 percent by weight; 70 to 80 percent asbestos is considered typical.
Frequently used binders include starches, elastomers, silicates, and cement;
mineral wool, clay, and lime are commonly used fillers.
There are many commercial, residential, and industrial uses of asbestos
millboard. Specific industrial applications include thermal protection in
large circuit breakers in the electrical industry; lining for covers and
troughs in the aluminium, marine, and aircraft industries; and .insulation in
glass tank crowns, melters. refiners, and sidewalls in the glass industry.
Very thin millboard is sometimes cut for use as gaskets. Commercial
applications include fireproof wallboard linings for safes, dry cleaning
machines, incinerators, and spark and glare shields in welding shops.
Residential applications include tent shields, stove mats and linings for
stoves, heaters, and electrical switchboxes.
(2) Pipeline Wrap
Asbestos pipeline wrap is an asbestos paper product similar to
asbestos roofing felt. It is made with approximately 85 percent asbestos and
15 percent cellulose fibers and starch binders. Asbestos is used in pipeline
wrap because it resists soil, chemicals, rotting, and decay, while maintaining
dimensional stability throughout its lifetime.
The largest user of this product is the oil and gas industry with their
extensive underground piping networks; there is some use by the chemical
industry for underground hot water and steam piping. The asbestos felt
protects the pipe from moisture, corrosion, rot, and abrasion. Pipeline wrap
is used minimally in above-ground applications, such as for special piping in
cooling towers. Pipeline wrap is applied to the pipe by high-speed wrapping
machines. The wrap is usually attached or bonded to the pipe surface by
special adhesive coatings or by hot enamels that are coated onto one side of
- 48 -
-------
the wrap. The pipeline wrap is designed to last the service life of the
pipeline to which it is applied.
(3) Beater-Add Gaskets
Beater-add gaskets are installed to provide tight, non-leaking
connections in piping and other joints. Asbestos is used in gaskets because
it is heat resistant, resilient, strong, and chemically inert. Asbestos
beater-add gasket papers contain approximately 60 to 80 percent asbestos and
(-
20 to 40 percent binders. Binders that are used include latex, styrene-
butadiene, acrylic, acrylonitrile, neoprene, fluoroelastomeric polymers, and
silicone polymers. The binder determines the material's suitability for use
in water, aqueous solutions, oil, fuel, or chemical environments.
These gaskets are primarily used in the automotive industry as heat
gaskets, carburetor gaskets, and oil and transmission gaskets and in trains,
airplanes, and ships. They are also used in a variety of industrial and
commercial equipment, such as boilers and furnaces. Asbestos gaskets are also
used widely in the chemical industry because of their chemical inertness.
(4) High-Grade Electrical Paper
Asbestos is non-flammable and has high thermal and electrical
resistance, properties which make it very useful as an electrical insulator.
Asbestos high-grade electrical paper is composed of 80 to 85 percent asbestos,
encapsulated in high-temperature organic binders. Generally, the paper
contains asbestos fibers and cellulose bound with latex polymers. Chemical
treatment is sometimes used to remove trace elements from asbestos fibers.
The major use of asbestos electrical paper is in insulation for high
temperature, low voltage applications. It may be used in motors, generators,
transformers, switch gears, and other heavy electrical apparatuses, usually at
operating temperatures of 266*F to 428°F.
- 49 -
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(5) Specialty Pacers
Specialty papers are produced in small volume for specific end
uses. The products in this subcategory include transmission paper, filter
paper, cooling tower fill, metal lining paper, electrical wire or cable
wrapping paper, and industrial and decorative laminates (OSHA 1986b).
Transmission paper, because of its structural stability and oil resistance,
has been used as a covering for metal transmission disks in automatic
transmissions.
Asbestos has been used in filters for the purification and clarification
of liquids because it offers an exceptionally large surface area per unit of
weight and has a natural positive electrical charge which is very useful for
removing negatively charged particles found in beverages (Krusell and Cogley
1982).
Asbestos filters may contain, in addition to asbestos, cellulose fibers,
various types of latex resins, and occasionally, diatomaceous earth (Krusell
and Cogley 1982). The asbestos content of beverage filters ranges from a low
of 5 percent, for rough filtering applications, to a high of 50 percent, for
very fine filtering. In general, the higher the asbestos content, the better
the filtering qualities of the filter (Krusell and Cogley 1982).
Applications of the asbestos filter paper are found primarily in the beer,
wine, and liquor distilling industries where they are used to remove yeast
cells and microorganisms from liquids. Asbestos filters are also used for
filtration of some fruit juices, such as apple juice, and for special
applications in the cosmetics and Pharmaceuticals industries.
b. Process Descriptions
(1) Primary Manufacture
The main operations in all asbestos paper primary manufacturing
are receiving, bag opening, mixing, forming, and finishing. In the fiber
- 50 -
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introduction operation, raw asbestos is most often introduced in unopened
pulpable bags, although for certain types of paper the fiber is dumped from
the bags. In cases where the fiber is dumped from the bags, asbestos is
obtained in non-compressed pulpable bags so that the bags may be slit and the
asbestos added directly to the mixer. At the mixing stage the fiber is
immediately wetted.
As in other manufacturing processes, the asbestos fiber is carried under
negative pressure by conveyor to the mixer. There, the fiber is wet-mixed
with paper stock, binder, and other ingredients. The stock slurry flows into
the papermaking machine and forms a sheet. The solids content of this sheet
may be less than five percent; the moisture content of this sheet is reduced
greatly during transit through the paper machine. The wet nature of the
material precludes the release of asbestos fiber.
The forming of asbestos paper is completed during the drying, slitting,
and calendering stages. The final operation involves rewinding in which the
paper products are bulk packaged on spools, reels, or beams from the larger
rolls. Rewinding is a dry operation.
There are certain primary manufacturing procedures that are specific to
the individual products within the paper products category, although most of
the operations are similar if not identical.
Asbestos millboard j,s manufactured in essentially the same process that is
used in the general paper manufacturing industry (i.e., the operations
described above). A cylinder is rotated in a vat of pulp, creating a thin
fiber coating. The coating is removed from the cylinder and drawn through a
process for partial dewatering. Sheets are wound continuously until the
desired board thickness is obtained. The built-up layer of material is cut
lengthwise and removed for drying. Herein lies the principle difference
between millboard and paper manufacture. Paper is manufactured into a
- 51 -
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continuous sheet while millboard is not. Standard size millboards are 42 x 48
inches and 1/32- to 3/4-inch thick. The most popular thicknesses are 1/4- and
1/2-inch millboards.
Pipeline wrap is manufactured on conventional papermaking machines. The
manufacture of pipeline wrap differs from the manufacture of other paper
products in that the felt is saturated with coal tar or asphalt before drying.
In addition, it is usually reinforced with parallel strands of fiberglass.
After saturation, the felt passes over a series of hot rollers which set the
coal tar or asphalt into the paper. The felt then passes over a series of
cooling rollers that reduce the temperature and provide a smooth surface
finish. The felt is then air-dried, rolled, and packaged.
Beater-add gaskets are manufactured on conventional papermaking machines
by the same process as the other paper products and are, therefore, considered
paper products. The binder is added during the beater process, which is how
the name "beater-add" gaskets originated. The gasketing paper is usually
produced in a sheet or roll varying in thickness from approximately 1/64-inch
to 1/16-inch. Most gasket paper is sold to fabricators who cut the beater-add
paper to customer-specified sizes and dimensions. The gaskets may be further
processed by reinforcing the gasket with wire or by sheathing the paper with
various metals, foils, plastics, or cloth.
Electrical paper is manufactured in rolls, sheets, and semi-rigid boards.
The rolls and sheets are manufactured on conventional papermaking machines.
Boards are formed on wet process board machines.
Asbestos specialty papers (specifically filter paper) are made on a
conventional papermaking machine. Due to the very low demand for certain
types of specialty paper, the machines are generally used to produce more
popular paper products, such as the non-asbestos filter substitutes (i.e.,
diatomaceous earth and cellulose fiber products (Krusell and Cogley 1982).
- 52 -
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(2) Secondary Manufacture
For paper products, there is secondary processing during the
manufacture of millboard, beater-add gaskets, electrical paper, and specialty
papers. Final fabrication of millboard usually involves cutting, trimming,
and shaping to meet the requirements of the space into which the millboard is
to be installed. Secondary manufacturers of gaskets cut the gaskets from
paper sheets using metal die stamping or processing machinery.
c. Production and Employment
Table 8 presents the total production and asbestos consumption, and
estimates of total employees exposed to asbestos for each type of paper
product. The data presented are based on 1985 figures, excluding companies
that no longer produce asbestos products. The estimates of total employment
are based on figures from the ICF Market Survey (1986-1987), supplemented by
figures from the ICF Exposure Survey (1986-1987). For producers who did not
provide employment data, we estimated employment from the average number of
workers per ton of asbestos consumed for each product type, based on available
data. Employment figures presented in the table should be considered
estimates only.
In addition, 2.7+ tons of asbestos millboard were imported into the U.S.
in 1985 (one company failed to provide data). Secondary processors of
millboard employ a total of over 448 asbestos workers (ICF Market Survey
1986-1987). Due to numerous refusals by secondary processors to supply either
asbestos mixture consumption or population data, it is not possible to
estimate populations for these facilities; therefore, the population estimate
for secondary manufacture of millboard is a lower bound estimate. 1981 TSCA
Section 8(a) data were not adequate to refine this estimate.
In 1985, 2,898 tons of pipeline wrap were imported (ICF Market Survey
1986-1987). There is, however, no secondary manufacturing.
- 53 -
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Table 8. . Production and Employment for Primary Manufacture
of Paper Products
Total Asbestos
Production3 Consumption"
(tons) (tons)
Total
Population
Exposed
to Asbestos0
Millboard
Pipeline Wrap
Beater-Add Gaskets
High-Grade Electrical Paper
Specialty Paper
581
276,949 sq.
16,505
698
434
435.8
1,333.0
12,436.4
744.0
300.3
12
27
227
27
6
a!985 production, excluding production by companies no longer producing
asbestos products.
"1985 consumption, excluding consumption by companies no longer
producing asbestos products.
Population based on IGF Market Survey (1986-1987) (1985 employment
excluding companies no longer producing asbestos products), ICF
Exposure Survey (1986-1987), and estimates described in the text for
companies with no population figures reported.
Sources: ICF Market Survey 1986-1987, ICF Exposure Survey 1986-1987,
and ICF estimates.
- 54 -
-------
Total 1985 imports of beater-add gaskets are estimated at over 5.6 tons.
Because few data were supplied by secondary manufacturers of beater-add
gaskets for the ICF Market Survey (1986-1987), total population for secondary
processing of beater-add gaskets was estimated by adjusting 1981 populations
from the TSCA Section 8(a) data (RTI 1985) to 1985 populations by multiplying
by the ratio of 1985 primary production (ICF Market Survey 1986-1987) to 1981
primary production (EPA 1986b, midpoint was used). The exposed population was
estimated to be 1,264 for secondary manufacturing of beater-add gaskets.
Secondary processing of high-grade electrical paper potentially exposes 20
workers to asbestos (ICF Market Survey 1986-1987). There are no imports of
high-grade electrical paper.
Secondary processing of specialty papers potentially exposes 145 workers.
An estimated 1 ton of specialty paper was imported in 1985 (ICF Market Survey
1986-1987).
d. Exposure Profile
Airborne asbestos fibers are generated throughout the entire
asbestos paper manufacturing process. This is the case for all five of the
products specified in this category. Table 9 presents the exposure profile
for each paper product as determined from the raw monitoring data. We
categorized the jobs performed by each worker monitored into one of several
job categories. Geometric and arithmetic means were calculated for the data
by job category. This summary table includes the results for primary and
secondary manufacturing of asbestos paper products.
- 55 -
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Table 9. Exposure Profile for Paper Product*
ui
CT\
8-Hour TWA Exposure (f/cc)
Product
Job Category*
Population
Pre-p,^ f/cc PELC
Geometric Mean
Arithmetic Mean
Post-0.2
Geometric Mean
f/cc PEL"
Arithmetic Mean
Duration
(hr/day)'
Frequency
(days/year)1
Primary Manufacturing
Millboard
Pipeline Wrap
Beater-Add Gaskets
Hlgh-Grade Electrical Paper
Specialty Paper
Fiber Introduction
Processing
Other
Total
Fiber Introduction
Processing
Other
Total
Fiber Introduction
Processing
Other
Total
Fiber Introduction
Processing
Other
total
Fiber Introduction
Processing
Other
Total
3
3
6
12
8
9
i2
27
20
11*
93
227
*
13
18.
27
1
3
2
6
0.091 (6)
0.013 (23)
0,052 (5}
0.052
0.091 (6)
0.013 (23)
0.052 (5)
0.051
0.091 (6)
0.013 (23)
0.052 (S)
0.036
0.091 (6)
0.013 (23)
0.052 (5)
0.039
0.091 (6)
0.013 (23)
0.052 (51
0.039
0.13*
0.030
0.070
0.076
0.13*
0.030
0.070
0.076
0.134
0.030
0.070
O.OS6
0.13*
0.030
0,070
0.060
0.13*
0.030
0.070
0.061
0.079
0.013
0,05.2
0.0*9
0.079
0.013
0.052
0.0*7
0.079
0.013
0.052
0.03S
0.079
0.013
0.052
0.037
0.079
0.013
0.032
0.037
0.09*
0.030
0.070
0.066
0.09*
0.030
0.070
0.06*
0.09*
0.030
0.070
0.052
0.09*
0.030
0.070
0.05*
0.09*
0.030
0.070
0.05*
8
8
8
8
8
8
8
8
8
8
8
a
a
8
8
8
8
8
8
172
172
252
211
172
172
250
201
172
172
2JO
20*
172
172
8250
201
172
172
250
198
Secondary Manufacturing.
Millboard
Beater-Add Oeaketa
High-Grade Electrical Paper
Specialty Paper
H/A
H/A
H/A
H/A
**8+
1,26*8
20
1*5
0.016 (26)
0.016 (26)
0.016 (26)
0.016 (26)
0.022
0.022
0.022
0.022
0.016
0.016
0.016
0.016
0.022
0.022
0.022
0.022
8
8
8
8
250
250
250
250
"job categorie* are baaed on a concise cetegorication of the job titles.
bEstimatlon of total population and the distribution of the population into Job categorlea la described in the text. Population by Job category la estimated
from the 1981 TSCA Section 8(a) data (Hendrickson and Dorla 1983).
cThes« values represent geometric and arithmetic means of the raw 8-hour THA exposure data. The number of data points ia given in parentheses. The values
corresponding to the total populations are calculated as weighted average* baaed on the number of worker* exposed in each Job category. Since the monitoring
data la aggregated for all paper producta, the exposure values for each Job category are assumed to be equivalent for all products.
-------
Table 9 (Continued)
The** post-0.2 f/cc PEL exposure value* are calculated directly from the raw monitoring data. Each 8-hour THA exposure value that 1* above 0.2 f/cc 1*
reduced to exactly 0.2 f/cc. Data that are already at or below this value remain unchanged. The value corresponding to the total population la determined in
the game manner as the pre-0.2 f/cc PEL total exposure value.
eTh* effective duration of exposure is 6 hours/day in all cases. Where no duration is provided, 8 hours/day is assumed. Exposure* for lea* than 8 hour* are
converted to 8-hour TWA* when not already appearing aa such, assuming zero exposure during perioda Mien the worker la not handling asbeatoa.
Frequency refera to the number of day* annually that the workers are performing a task involving potential exposure to asbestos. The frequency la not
assumed to be 250 days/year for all primary paper manufacturing since data for specific job type* indicates otherwise. Data from the ICF Exposure Survey
(1986-1987) show* typical frequencies to be 172 days/year for stock preparation (categorized as fiber introduction) and paper machine operation (categorized
as processing).
8Thls total population was estimated by adjusting 1981 TSCA Section 8(a) population (RTI 1985) to 198S by multiplying by the ratio of 1985'primary production
(ICF Market Study 1986-1987) to 1981 primary production (EPA 1986b).
Sources: ICF Market Survey 1986-1987, ICF Exposure Survey 1986-1987, OSBA 1987.
Ui
-------
Since the monitoring data are aggregated for all paper products, the
durations, frequencies, and exposures for each job category are assumed to be
equivalent for all paper products. However, since the distribution of the
total populations into job categories developed from 1981 TSCA Section 8(a)
data (Hendrickson and Doria 1983) for primary manufacturing is different for
each product, the weighted average exposures and frequencies for each product
vary among the various paper products.
The total population values for each specific product are based on the ICI
Market Survey (1986-1987). The populations for manufacturing sectors for
which population data were not available are estimated by using the ratio of
population to amount of asbestos fiber consumed for all other paper products.
The distribution of the total number of workers exposed into specified job
categories is based on 1981 TSCA Section 8(a) data (Hendrickson and Doria
1983).
For secondary manufacturing of paper products, the total populations are
not disaggregated into job categories. Population data were not available foi
all secondary manufacturers of millboard; thus, the population for secondary
processing of millboard is most likely larger than the value indicated. 1981
TSCA Section 8(a) data are not adequate to refine this estimate. The
populations for secondary beater-add gasket companies for which population
data were not available are estimated from the ratio of population to asbestos
consumption for the other secondary beater-add gasket companies. Due to gaps
in data necessary to estimate total population for secondary processing of
beater-add gaskets, this population was estimated by adjusting the 1981
* In reality, however, sources indicate that exposure levels can vary
widely depending on the asbestos content of the product (OSHA 1986b). Levels
of exposure at a plant producing beater-add gasketing containing 90 percent
asbestos are expected to be higher than levels at a plant producing specialty
paper with a 10 percent asbestos content.
- 58 -
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population from the TSCA Section 8 (a) data (RTI 1985) to 1985 by multiplying
by the ratio of 1985 primary production (ICF Market Survey 1986-1987) to 1981
primary production (EPA 1986b, midpoint was used).
As indicated in Table 9, the primary manufacturing operation with the
greatest potential for causing asbestos exposure is fiber introduction. The
fiber introduction procedure in paper manufacturing involves the dumping of
asbestos into a beater or hydropulper. A local exhaust system with dust-
collection equipment is used to keep the processing area under negative
pressure. A primary method used to reduce exposure during this step is the
acquisition of asbestos in noncompressed pulpable bags. This enables the bags
to be slit open and the asbestos added directly to the mixer where it is
immediately wetted. Emissions can vary greatly at this point, depending on
the physical process employed. Some plants perform fiber introduction and
stock preparation in a single wet operation and others perform them as
separate operations.
The wet-mixing of the fiber with paper stock, binder, and other
ingredients controls the release of airborne asbestos. As in most other
industry sectors, the asbestos is transported to the mixer under negative
pressure by conveyor. Rigorous housekeeping and clean-up measures are
critical during mixing to prevent spillage of material. Central vacuum
cleaning systems and mechanical floor-sweeper-vacuum units are often used
during these operations.
Canopy hoods and exhausts that are utilized to remove water vapor and heat
from steam-heated rolls in the dry section also aid in asbestos dust control.
These devices augment the general ventilation in the dry processing area. At
the slitting and calendering stages, local exhaust ventilation (LEV), area
hoods, and central exhaust collection systems are the typical engineering
controls. Housekeeping is very important as well during these operations.
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LEV and hoods represent the normal dust control measures at the rewinding
step. This dry operation involves the bulk packaging of paper products on
spools, reels, or beams from larger rolls. Control of airborne fibers in the
workplace has been and should continue to be achieved mostly by LEV and strict
housekeeping and work practices. Respirators are likely worn by personnel at
bag opening, pulping, and scrap handling operations.
All job categories comprising the manufacture of asbestos papers have been
able to achieve mean exposure levels below 0.2 f/cc; this is indicated by the
values exhibited in Table 9 for all job categories. Out of all the monitoring
data shown in Table B-l for primary manufacturing, only a few samples are
above the 0.2 f/cc level; all of these data fall under the fiber introduction
job category. Assuming that in these few cases additional controls will be
utilized to achieve 0.2 f/cc exposure levels, the projected exposure under the
new PEL will decrease.
Table 9 indicates that the average post-0.2 f/cc PEL exposure level for
the total exposed population of each paper product (calculated by the
proportion of workers in each job category) is only slightly lower than the
pre-0.2 f/cc PEL value. The decrease is solely due to changes in the fiber
introduction job category.
No changes are projected for secondary manufacturing of paper products.
As indicated in Table 9, the pre- and post-0.2 f/cc PELs are identical; this
is due to the absence of any monitoring data greater than 0.2 f/cc. Job
categories are not identified for secondary manufacturing because all tasks
fit under the general category of fabrication.
2. Asbestos-Cement Pipe
a. Product Description
Asbestos-cement pipe is used primarily for transporting drinking
water (pressure pipes) and for draining storm water, sewage, and other liquid
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waste (non-pressure pipes). Other applications are in industrial products,
air/gaseous products, and electrical conduit for heating, cooling, and
gas-venting. The composition is generally 15 to 25 percent asbestos by
weight, 42 to 53 percent Portland cement, and 34 to 40 percent ground silica
sand.
The use of A/C pipe appears to be regional, primarily occurring in the
Southwest. The use of raw asbestos in the production of A/C pipe dropped
significantly between 1981 (129,800 metric tons) and 1982 (37,600 metric tons)
but has remained fairly constant since then (i.e., 26,100 tons in 1983, and
37,000 tons in 1984) (OSHA 1986b). In 1985, approximately 32,691 tons of
asbestos fiber were consumed in this sector (ICF Market Survey 1986-1987).
Manufacturers produced 216,903 tons of A/C pipe in 1985, and employed 286
asbestos workers; there are no known imports (ICF Market Survey 1986-1987).
b. Process Description
Asbestos-cement (A/C) pipe is composed of a mixture of Portland
cement, finely ground silica, and asbestos fibers (ICF 1984). The process as
a whole consists of four distinct steps: raw material blending, pipe forming,
curing/autoclaving, and finishing. In the blending step, asbestos fiber is
fluffed and separated in a willow, then silica and Portland cement are added
to form a dry mix. Water is added to the dry mix, and the mixture is blended
to form a homogeneous slurry. The slurry is fed onto a moving felt conveyor
and water is drawn through the felt by a vacuum to form a continuous
asbestos-cement sheet. The sheet is wound onto a cylindrical mandrel until it
reaches the desired thickness, and thus, forms a pipe. The pipe is loosened
electrolytically by producing gases between the mandrel and the formed pipe.
After a short time, the mandrel is removed and the pipe is cured. Curing is
either by water immersion or pressurized steam called autoclaving. This
autoclaving step enhances corrosion resistance to high sulfate soils and
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waters. After the curing/autoclaving step, the pipe is passed to the
finishing area where the pipe is cut to size and the ends are trimmed and
machined to facilitate junctions. A/C pipes are produced in a variety of
diameters, formulations, and weights designed for different applications.
Diameters may range from 4 to 42 inches, and standard lengths are 10 to 13
feet.
A/C pipe undergoes little or no secondary processing (Anderson et. al.
1983). The user of this product (i.e., the construction industry) may perforn
some cutting of the pipe at the sites of the installation.
c. Exposure Profile
The total exposed population is based on the ICF Market Survey
(1986-1987). The population for companies for which no data were available is
estimated by using the ratio of population to amount of asbestos fiber
consumed for the other companies. The total population is allocated into job
categories using the 1981 TSCA Section 8(a) data (Hendrickson and Doria 1983).
The data presented in Table 10 are based on 1985 figures, excluding companies
that no longer produce asbestos products.
Data indicate that exposure levels to asbestos fibers in A/C pipe
manufacturing may vary widely from process to process. This is revealed in
Table 10 which presents the exposure profile for A/C pipe production as
determined from the raw monitoring data.
This summary table shows geometric and arithmetic mean exposure values
ranging from quite low for certain miscellaneous jobs (i.e., the "other" job
category) to close to 0.2 f/cc for finishing operations; this rather high
value for finishing correlates to exposure during certain dry mechanical
operations. Exposures at coupling cut-off operations in an A/C pipe plant
have been shown to average 0.369 f/cc, higher than any other operations (Bragg
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Table 10. Exposure Profile for A/C Pipe — Primary Manufacture
8-Hour TWA Exposure (f/cc)
Product Job Category*
Population
Pre-0.2 f/cc PEL0
Geometric Mean
Arithmetic Mean
Post-0.2
Geometric Mean
f/cc PEL"
Arithmetic Mean
Duration
(hr/day)*
Frequency
(days/year)
Primary Manufacturing
A/C Pip* Fiber Introduction
Pipe Forming
Finishing
Other
Total
14
49
109
114
286
O.OS3 (2)
0.077 (34)
0.171 (79)
0.047 (44)
0.100
0.103
0.129
0.311
0.080
0.178
O.OS3
0.071
0.117
0.046
0.078
0.103
0.096
0.141
0.072
0.104
8
8 '
6
e
8
250
2SO
250
250
250
"job categories are based on a concise categorization of the job titles.
bEstimation of total population and the distribution of the population into Job categories is described in the text. Population by job category is estimated
from the 1981 TSCA Section 8(a) data (Hendrlckson and Oorla 1983).
cThese values present geometric and arithmetic means of the raw 8-hour TWA exposure data. The number of data points is given in parentheses. The value
corresponding to the total population Is calculated as a weighted average based on the number of workers exposed in each Job category.
These post-0.2 f/cc PEL exposure values are calculated directly from the monitoring data. Each 8-hour THA exposure value that is above 0.2 f/cc ia reduced
to exactly 0.2 f/cc. Data that are already at or below this value remain unchanged. The valua corresponding to the total population ia determined in the
same manner as the pre-0.2 f/cc PEL total exposure velue.
*The effective duration of exposure is 6 hours/day in all cases. Where no duration is provided, 8 hours/day is assumed. Exposures for less than 8 hours are
converted to 8-hour THAs, assuming cero exposure during periods when the worker is not handling asbestos.
Frequency refers to the number of day* annually that the worker* are performing a task involving potential exposure to asbestos. The frequency is assumed to
be 250 days/year unless data for specific job types indicates otherwise.
Sources: ICF Exposure Survey 1986-1987, Clarke 1986, OSHA 1987, ICF Market Survey 1986-1987.
-------
1986). This operation involves the repetitious cutting of A/C pipe coupling
into small sections for use in pipe connections.
As indicated in Table 10, the value for finishing operations can be
expected to decrease significantly to a post-0.2 f/cc PEL geometric mean
exposure level of about 0.12 f/cc (or an arithmetic mean exposure level of
0.14 f/cc). This can be accomplished via engineering controls. Engineering
controls during the coupling cutoff operations and other A/C pipe dry
finishing processes (e.g., drilling and lathing) typically include custom-
engineered hoods, local exhaust systems, wet sawing, and special single-point
cutting tools (OSHA 1986b). The control most widely used for all phases of
pipe production is local exhaust ventilation (LEV) with hooding. LEV draws
airborne asbestos fibers away from workers; the fibers are collected in
baghouses. These systems are used during bag opening, fiber introduction, dry
mixing, willowing (fluffing), dry finishing of both pipes and fittings, and
scrap grinding for recycling.
There is minimal generation of asbestos dust for A/C pipe production
processes other than dry finishing. Fiber emitted between fiber introduction
and wet mixing from material handling equipment (e.g., screw conveyors and
bucket elevators) is controlled by using continuous exhaust and maintaining
negative pressure within pneumatic conveying systems. The fluffing, blending,
and dry mixing of the asbestos fiber (with cement, silica, and scrap) take
place automatically in closed blending tanks maintained under negative
pressure by LEV. These engineering controls reduce the possibility of
exposure at these processing stages (OSHA 1986b). No special control
equipment is typically used during pipe formation, air curing, and steam
curing since the asbestos fibers in the pipe become bound in a cement mixture,
thus restricting fiber release.
- 64 -
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Good housekeeping practices are also important during pipe formation.
These practices include the use of wet vacuum machines and squeegees, instead
of brooms, to clean up spills of slurry that could become a source of
emissions. Central "vacuum systems with flexible-hose pickups are also used at
work stations vulnerable to asbestos spillage (e.g., bag opening). Other
prevalent work practices include minimum handling of asbestos bags prior to
bag opening and fiber introduction, as well as not recirculating local exhaust
air.
As expressed by the values exhibited in Table 10, no exposure level change
is expected during the fiber introduction activities. A small decrease may
occur for pipe forming and "other" activities via the previously discussed
controls and practices. The primary reduction, however, occurs due to the
expected decrease in exposure during finishing operations.
3. Asbestos-Cement Sheet
a. Product Descriptions
Asbestos-cement (A/C) sheet includes flat sheet, corrugated sheet,
and roofing and siding shingles. Corrugated A/C sheet is no longer produced
in the United States; however, it is imported (ICF Market Survey 1986-1987).
Flat A/C sheet is used primarily in the construction industry as wall
lining in factories and agricultural buildings, fire-resistant walls, curtain
walls, industrial partitions, soffit material (covering the underside of
structural components), and decorative paneling in both exterior and interior
applications. In addition, it is used for special applications in cooling
towers, and as laboratory table tops and fume hoods, electrical equipment
mounting panels, and as a component of vaults, ovens, safes, heaters, and
boilers. Flat A/C sheet is found in schools as well as in residential
construction.
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A/C shingles are used as siding and roofing for both residential and
commercial buildings. Roofing shingles account for approximately 70 percent
of the A/C shingle market, and siding shingles take the remainder.
Production of A/C sheet products has declined significantly since 1981
(ICF Market Survey 1986-1987). In 1985, 181,808 squares of A/C sheet materi
were manufactured in the U.S. (one square - 100 square feet), consuming
4,481.8 tons of asbestos (ICF Market Survey 1986-1987). Only ,three percent
this total production is flat A/C sheet, the remaining 97 percent is A/C
shingles. An additional 3,395.7 squares of flat A/C sheet were imported in
1985. The numbers of asbestos workers are 12 and 11 for flat sheet and
shingle primary processing, respectively (ICF Market Survey 1986-1987). Ther
are currently no secondary manufacturers of A/C sheet or shingle in the U.S.
(ICF Market Survey 1986-1987).
b. Process Descriptions
The production process for flat sheet and shingles is very similar
A/C sheet products are made from a mixture of Portland cement and asbestos
fiber. Finely ground inert filler such as silica and pigments are sometimes
included. In general, asbestos-cement sheet contains between 15 and 40
percent asbestos fiber. However, for curing in short-time periods, a general
formulation of 12 to 25 percent asbestos, 45 to 54 percent cement, and 30 to
40 percent silica is used (ICF 1984). Similar to the A/C pipe process, the
raw materials are mixed with water to form a wet slurry of asbestos, cement,
and silica. The slurry is then picked up by a screen-cylinder mold and
transferred to a felt conveyor. The felt is then dewatered, passed to a
mandrel, and wound to the desired thickness. After achieving the required
thickness, a cut is made across the width of the sheet. The sheet is manually
peeled off the rotating mandrel onto a transfer roll conveyor. The sheet is
then cured, and processed through embossing rollers and trimming/cutting
- 66 -
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wheels. Roofing and siding shingles are cut from A/C sheets; therefore, the
composition and manufacturing process used are the same.
c. Exposure Profile
The total population is based on the ICF Market Survey (1986-1987).
The distribution of the total number of workers exposed into specified job
categories is based on the 1981 TSCA Section 8(a) data (Hendrickson and Doria
1983). The data presented in Table 11 are based on 1985 figures, excluding
companies that no longer produce asbestos products.
Although the manufacturing processes of A/C sheet are very similar to
those of A/C pipe, asbestos dust is apparently less well-controlled in A/C
sheet plants, resulting in higher exposure readings. This is exemplified by
the total pre-0.2 f/cc PEL level for primary manufacturing shown in Table 11.
The values for all primary job categories depicted in Table 11 are very high,
with two out of three of the job categories having exposure values above 1.0
f/cc. Since the monitoring data are aggregated for A/C sheet and A/C
shingles, the exposure values and other information for each job category are
assumed to be equivalent for both products. However, since the distribution
of the total populations into job categories developed from 1981 TSCA Section
8(a) data (Hendrickson and Doria 1983) for primary manufacturing is different
for each product, the weighted average exposures are different for the two A/C
sheet products.
With the widespread employment of exposure controls, the post-0.2 f/cc PEL
exposures are assumed to fall at or below the 0.2 f/cc level. The controls in
use for A/C sheet production, like the process itself, are similar to those in
A/C pipe manufacture. LEV is the primary control technology. It could be
used in such operations as bag opening, fiber introduction, punching,
trimming, and brushing, as well as along the forming line during rolling,
veneering, cutting, and embossing. The willowing and mixing operations are
- 67 -
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Table 11. Exposure Profile for A/C Sheet -- Primary Manufacture
00
8-Hour TWA Exposure (f/cc)
Product Job Category8
Population
Pre-0.2 f/cc PEL0
Geometric Mean
Arithmetic Mean
Post-0 t2
Geometric Mean
f/cc PEL"
Arithmetic Mean
Duration
(hr/day)"
Frequency
< days/year )f
Primary Manufacturing.
A/C Flat Sheet Fiber Introduction
Proceeding
Other
Total
A/C Shingle Fiber Introduction
Processing
Other
Total
2
7
3
12
1
7
3
11
1.054 (7)
0.408 (6)
1.028 (6)
0.671
1.054 (7)
0.408 (6)
1.028 (6)
0.636
1.364
0.577
l.}43
0.850
1.364
0.577
},143
0.803
0.200
0.166
0.200
0.160
0.200
0.166
0.200
0.178
0.200
0.172
0.200
0.184
0.200
0.172
0.200
0.182
8
8
8.
8
8
8
8
8
250
250
250
250
250
250
250
250
"job categories are based on a concise categorization of the job tltlea.
Estimation of total population is described in the text. Population by Job category is estimated froa the 1981 TSCA Section 8(a) data (Hendrlckson and Doria
1983).
°These values represent geometric and arithmetic means of the raw 8-hour THA exposure data. The number of data points is given in parentheses. The values
corresponding to the total population are calculated aa weighted averages baaed on the number of workers exposed in each job category. Since the monitoring
data are aggregated for A/C sheet and A/C shingles, the Job category exposure values are assumed to be equivalent for both products.
These post-0.2 f/cc PEL exposure values are calculated directly from the monitoring data. Each 8-hour THA exposure value that la above 0.2 f/cc ia reduced
to exactly 0.2 f/cc. Data that are already at or below this value remain unchanged. The values corresponding to the total populations are determined in the
seme manner as the pre-0.2 f/cc PEL total exposure value.
*The effective duration of exposure ia 8 hours/day in all cases. Where no duration ia provided, 8 hours/day is assumed. Exposures for less than 8 hours are
converted to 8-hour TWAs, assuming sero exposure during periods when the worker is not handling asbestos.
Frequency refers to the number of days annually that the workers are performing a teak involving potential exposure to eabestoa. The frequency is assumed to
be 250 daya/year.
Sources: OSHA 1987, ICF Market Survey 1986-1987.
-------
controlled with the use of negative pressure conveying systems, closed
vessels, and isolation in a restricted access area. Host finishing operations
can be controlled by adopting tools equipped with exhaust systems or wet spray
devices, as well as LEV. During sanding, however, supplemental respiratory
protection is needed to prevent excessive exposure to asbestos dust.
Housekeeping and work practices also greatly reduce the amount of airborne
dust and, as in all industries, provide very effective dust control.
The fiber introduction, and dry and wet mixing stages of A/C sheet produc-
tion are virtually equivalent to the steps used in A/C pipe production; so
exposures in these processes can be kept low. The advanced processing steps
are also similar to those of A/C pipe with relatively little fiber dust gener-
ation. As with pipe manufacturing, the highest and most difficult exposures
to control occur after curing, during the mechanical finishing operations.
4. Friction Products
a. Product Descriptions
The friction product category includes the following products:
Drum brake linings;
Disc brake pads (light and medium);
Disc brake pads (heavy);
Brake blocks;
Clutch facings;
Automatic transmission components; and
Friction materials.
Each of these products is discussed briefly below.
(1) nfVTfl firake Linings
Most light and medium vehicles (i.e., passenger cars and light
trucks) are equipped with drum brakes on the rear wheels. Drum brake linings
are pieces of molded friction material attached to curved pieces of metal
(brake shoes), aligned to a cylinder or drum which rotates with the wheel.
The vehicle is stopped by friction between the drum and the lined brake shoes
- 69 -
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when pressure is applied to the brake. (The term "brake shoe" is sometimes
used to refer to the lined piece, not the metal piece alone.)
(2) Disc Brake Pads (Light and Medium)
Disc brakes are generally used on the front wheels of light an
medium vehicles, although some cars, primarily high-performance types, have
disc brakes on all four wheels. In disc brakes, two metal pieces, lined with
friction material called disc brake pads, straddle the rotor,, or disc, in the
center of the vehicle's wheel. Friction between the disc and the brake pad
slows or stops the vehicle when the brakes are applied.
In addition to disc brake pads containing asbestos fibers as a component
of the friction material, there are some semi-metallic disc brake pads which
have asbestos-containing underlayers between the plate and the pad (other
semi-metallic pads have no underlayers or non-asbestos underlayers). These
products are not considered asbestos disc brake pads.
(3) Disc Brake Pads (Heavy)
Asbestos disc brake pads are rarely used for heavy vehicles.
Disc brakes for heavy vehicles are similar to those described for light and
medium vehicles. Asbestos disc brake pads for heavy vehicles differ from
those for light and medium vehicles primarily in size; therefore, information
in the previous section on disc brake pads is applicable to disc brake pads
for heavy vehicles as well.
(4) Brake Blocks
Brake blocks are drum brake linings for heavy vehicles (trucks
and off-highway vehicles). Drum brakes for heavy vehicles are similar to the
drum brakes described for light and medium vehicles. Brake blocks are
generally considerably larger than automobile drum brake linings (0.75 inches
or greater in thickness, compared to about 0.3 inches for automobile drum
brake linings), but their operation is similar.
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(5) Clutch Facings
Clutch facings are friction materials attached to the steel
disc in a manual transmission vehicle. Pressure plates pressing against the
clutch facings keep the gears in position when the clutch is engaged. Clutch
facings may be molded products, usually reinforced with yarn or wire, or woven
products (see Section B.5, Textiles, of this chapter). Molded clutch facings
are more widely used than woven facings; woven clutch facings are more likely
to be used in high performance vehicles.
(6) Automatic Transmission Components
Automatic transmission components are used in fluid-filled
automatic transmissions for automobiles. The friction material is a type of
paper used to line a metal band around the gears and metal rings (friction
clutch plates) that fit over the gears. The entire assembly is fluid-filled;
the fluid absorbs the heat of gear-changing and also any wear debris from the
friction material.
(7) Friction Materials
This category covers a variety of non-automotive friction
materials, including the following (Scott 1984):
• Woven band brakes (see Section B.5, Textiles) for
heavy-duty use (e.g., in oil well drilling and
construction);
• Molded brake and clutch materials for industrial use;
• Railroad brakes;
• Paper-type friction materials for fluid-filled clutches for
industrial use; and
• Other friction materials for industrial use and for
equipment such as lawn mowers, washing machines, and
machine tools.
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b. Process Descriptions
(1) Primary Manufacture
Prvil Pra^e Linings. Asbestos drum brake linings contain
resins, fillers, and other additives, as well as asbestos fibers. Asbestos
fibers make up approximately 40 to 50 percent by weight of the linings (Cha
and Carter 1982). Primary manufacture of drum brake linings usually is
carried out by a wet-mix process, consisting of the following steps, with
possible variations by manufacturers:
• Mixing of fibers, solid and liquid resins, property
modifiers, and solvents;
• Extrusion or rolling;
• Molding and curing using heat and pressure;
• Finishing by grinding and drilling; and
• Packaging of finished product.
The degree of automation in manufacturing may be highly variable (ICF
1986a).
Disc Brake Pads (Light. Medium and Heavy Vehicles).
Asbestos disc brake pads, like drum brake linings, are molded products
containing resins, fillers, and other additives, as well as asbestos fibers.
These products are approximately 40 to 50 percent asbestos by weight (Cha and
Carter 1982). A dry-mix process is usually used in their manufacture; the
basic steps in this process are as follows:
• Mixing of fibers, dry resins, and property modifiers;
• Molding and curing using heat and pressure;
• Finishing by grinding and drilling; and
• Packaging of finished product.
The degree of automation of these steps may vary considerably from
manufacturer to manufacturer (ICF 1986a).
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Brake Blocks. Asbestos brake blocks are primarily molded
products usually produced by a dry-mix process, as described for disc brake
pads. Some woven brake blocks are also produced (see Section B.5, Textiles).
Clutch Facings. Molded clutch facings are usually made by
a dry mix process, as described for disc brake pads. The mix may be molded
around strand or wire reinforcements. Woven clutch facings are made by
running a strand through a wet mix to pick up the wet mixture and weaving
after drying. The woven product is then hot-pressed, cured, and ground, as
other wet-mix products.
Automatic Transmission Components. Paper for automatic
transmission components is manufactured by conventional paper-making
processes. Raw materials are pulped and fed to a continuous papermaking
machine, and finished paper is cut from the machine.
Friction Materials. Woven band brakes are produced from
asbestos cord, possibly reinforced with wire, which is passed through a
wet-mix to pick up resin and modifiers and then woven into tapes. The tapes
are heated to partially cure the resin, and then may be further cured to form
flexible rolls or rigid segments (Jacko and Rhee 1978).
Primary manufacture of molded brake and clutch materials is probably
similar to manufacture of molded automotive products.
Railroad brakes are manufactured by methods similar to those described for
drum brake linings.
Manufacture of paper-type industrial friction products is similar to the
manufacture of automatic transmission components for automobiles.
The manufacturing methods for other friction materials, which may include
molded, woven, and paper-type products, vary depending on the type and
application of the material.
- 73 -
-------
(2) ff^ondarv Manufacture
ppim Brake Linings. Secondary processing of drum brake
linings may be of several types. Some processors install new brake linings
into brake assemblies for new vehicles; others repackage linings for sale as
replacement parts in the aftermarket. Generally, neither of these secondary
processes involves any grinding or drilling of the brake linings; these
operations are usually performed by primary manufacturers. Anothe- distinct
type of secondary processing is automotive rebuilding. Rebuilders receive
used, worn brake linings, attached to the shoes. The old linings are removed
from the shoes, the shoes are cleaned by abrasion, and new linings are
attached. The rebuilt shoes with linings are then packaged and sold for the
aftermarket.
Disc Brake Pads (Light. Medjyn) find Heavy Vehicles).
Secondary processing of disc brake pads includes installation of the pads in*--
new brake assemblies and repackaging for sale to the aftermarket
addition, rebuilders remove the worn pads from the metal plates, clean tr._
plates, and attach new pads for resale.
Brake Blocks. Secondary processing for brake blocks
includes installation in new brake assemblies and automotive rebuilding, as
described for drum brake linings and disc brake pads. There may be some
repackaging of brake blocks.
Clutch Facings. Secondary processing of clutch facings is
similar to secondary processing of the automotive friction products previously
discussed. Clutch facings may be rebuilt, as described for other automotive
products.
Automatic Transmission Components. Secondary
manufacturing for automatic transmission components includes installation c.
- 74 -
-------
the componer.-._ .- new vehicle transmissions. Rebuilding of transmissions is
another type ; secondary processing.
Friction Materials. Secondary processing of woven band
brakes may involve cutting the band material and installing it in new
equipment. Rebuilding may include removing worn material and replacing it
with new material. Secondary manufacturing processes for other types of
friction materials may be similar to those described for automotive -friction
products; little information is available on non-automotive products, however.
c. Production and Employment
Table 12 presents total production and asbestos consumption and
estimates of total employees exposed to asbestos for each type of friction
product. The data presented are based on 1985 figures, excluding companies
that no longer produce asbestos products. The estimates of total employment
are based on figures from the ICF Market Survey (1986-1987), supplemented by
figures from the ICF Exposure Survey (1986-1987). For producers who did not
provide employment data, we estimated employment from the average number of
workers per ton of asbestos consumed for each product type, based on available
data. In the case of disc brake pads for heavy vehicles, the average for disc
brake pads for light and medium vehicles was used. For some products, there
were wide variations between companies in number of employees per ton of
asbestos consumed. This may indicate differences in the method of reporting
employees; for some companies, total employment may be reported, while for
others, only employees directly exposed to asbestos may be included. In
addition, the level of automation may vary considerably from company to
company. Employment figures presented in the table should be considered
estimates only.
There are a number of secondary processors of friction products. The ICF
Market Survey (1986-1987) includes automobile importers in the listing of
- 75 -
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Table 12. Production and Employment for Primary Manufacture
of Friction Products
Drum Brake Linings
Disc Brake Pads (Light
and Medium Vehicles)
Disc Brake Pads (Heavy
Vehicles)
Brake Blocks
Clutch Facings
Automatic Transmission
Components
Friction Materials
Total
Production*
(thousand
pieces)
91,922.4
58,633.5
146.9
3,752.7
7,237.1
55.5
8,521.4
Asbestos
Consumption0
(tons)
12,645.5
6,323.3
110.1
2,337.0
993.5
0.2
1,523.0
Total
Population
'Exposed
to Asbestos0
1,115
815
14
232
239
1
-•
a!985 production, excluding production by companies no longer producing
asbestos products.
°1985 consumption, excluding consumption by companies no longer
producing asbestos products.
Population based on ICF Market Survey (1986-1987) (1985 employment,
excluding companies no longer producing asbestos products), ICF
Exposure Survey (1986-1987), and estimates described in the text for
companies with no population figures reported.
Sources: ICF Market Survey 1986-1987, ICF Exposure Survey 198*
and ICF estimates.
- 76 -
-------
secondary manuracturers; and, therefore, it is difficult to obtain from this
source an estimate of the number of employees that actually carry out
secondary processing. In addition, the major emphasis of the Market Survey
was on primary manufacturing. Because the survey did not focus on secondary
processing, the number of secondary processors may be underestimated. Also,
brake rebuilders, who perform a type of secondary processing, were not
included in the survey. Because of these uncertainties, the IGF Market Survey
data on worker populations were not used in this analysis. To estimate the
potentially exposed worker population for secondary manufacture of each
friction product, populations from the 1981 TSCA Section 8(a) data (RTI 1985)
were adjusted to 1985 populations by multiplying by the ratio of 1985 primary
production (ICF Market Study 1986-1987) to 1981 primary production (EPA 1986b,
midpoints were used). Based on this estimating technique, less than one
full-time employee would be involved in secondary manufacture of disc brakes
for heavy vehicles and automotive transmission components. The total
population for secondary manufacture of all friction products was estimated to
be 2,295.
Population estimates by OSHA (1986b) for automotive rebuilding were used
in this analysis; OSHA (1986b) identified 181 plants with 4,750 workers for
brake rebuilding. The 1981 TSCA Section 8(a) data do not include data
specifically for automotive rebuilding. It is not known, therefore, whether
or not automotive rebuilding is included with secondary friction product
manufacturing data. If automotive rebuilding is included, there may be some
double counting using this method of estimating population.
d. Exposure Profile
To determine exposure levels during primary and secondary
manufacture of friction products, data from the ICF Exposure Survey
(1986-1987), NIOSH reports, and OSHA surveys were obtained. We categorized
- 77 - •
-------
the jobs performed by each worker monitored into one of several job
categories. Geometric and arithmetic means were calculated using the raw data
for each job category.
(1) Primary Manufacture
Table 13 presents a summary of the data on primary manufacture
of friction products. Processes used for the manufacture of the various types
of molded friction products are similar, and it was generally not possible to
categorize the available exposure data by product; therefore, we have assumed
that the geometric and arithmetic mean exposures for each job category apply
to each of the molded products. For woven friction products, refer to Sectionr
B.5 for exposure levels. For automatic transmission components, which are
paper products, exposures for specialty paper products apply (see Section
B.I); there were no exposure data specific to automatic transmission
components. (For friction materials, both molded products and paper products
may be included. No breakdown by type is available; we assumed for simplicity!
that the exposure values for molded products apply.)
The total number of workers exposed to asbestos during manufacture
type of friction product was estimated as described earlier (see Ta-
To estimate the number of workers by job category for each product, we used
the 1981 TSCA Section 8(a) data (Hendrickson and Doria 1983).
As Table 13 shows, the geometric mean, TWA exposures for three job
categories (fiber introduction and mixing, forming, and scrap and waste
disposal) exceed the 0.2 f/cc PEL. The arithmetic mean, TWA exposures are at
or above the 0.2 f/cc PEL for all job categories.
Based on exposure surveys received, it is likely that worker
categories with exposures exceeding 0.2 f/cc are required to wear . -^-
Some companies may require respirators for workers in all job categories VIC?
Exposure Survey 1986-1987). Engineering controls currently used in the
- 78 -
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Table 13. Exposure Profile for Friction Products -- Primary Manufacture
Product Job Category" Population
Pre-0.2
Geometric
Mean
f/cc
8 -Hour
PELC
Arithmetic
TWA Exposure
Mean
(f/cc)
Post-0.2
Geometric Mean
f/cc PELd
Arithmetic Mean
Duration
(hr/day)'
Frequency
(days /year)
f
Drum Brake Lining
Disc Brake Pad* (Light
and Medium Vehicles)
Disc Brake Pad*
(Heavy Vehicles)
vO
Brake Blocks
Clutch Facings
Fiber Introduction/ 212 0.251 (71) 0.487
Mixing
Forming 301 0.226 (301) 0.482
Finiehing 301 0.174 (336) 0.357
Inspection/Packing 101 0.104 (63) 0.404
Scrap/Haste Handling 100 0.240 (18) 0.515
Other 100 0.060 (68) 0.197
Total 1,115 0.192 0.420
Fiber Introduction/ 180 0.251 (71) 0.487
Mixing
Forming
Finishing
Inspection/Packing
Scrap/Wast* Handling
Other
Total
Fiber Introduction/
Mixing
Forming
Finishing
Inspection/Packing
Scrap/Haste Handling
Other
Total
Fiber Introduction/ 30 0.251 (71) 0.487
Mixing
Forming 60 0.226 (301) 0.482
Finishing 60 0.174 (336) 0.357
Inspection/Pecking 27 0.104 (63) 0.404
Scrap/Waste Handling 27 0.240 (18) 0.515
Other • 28 0.060 (68) 9.197
Totel 232 0.183 0.411
Fiber Introduction/ 72 0.251 (71) 0.487
Mixing
Forming 82 0.226 (301) 0.482
Finishing 82 0.174 (336) 0.357
Inspection/Packing 1 0.104 (63) 0.404
Scrap/Waste Handling 1 0.240 (18) 0.515
Other I 0.060 (68) 0.197
Total 239 0.215 0.439
236
236
55
54
_5i
815
2
4
3
2
2
_1
14
0.226 (301)
0.174 (336)
0.104 (63)
0.240 (18)
0.060 (68)
0.198
0.251 (71)
0.226 (301)
0.174 (336)
0.104 (63)
0.240 (18)
0.060 (68)
0.191
0.482
0.357
0.404
0.515
0.197
0.425
0.487
0.482
0.357
0.404
0.515
0.197
0.429
0.122
0.122
0.115
0.066
0.110
0.049
0.107
0.122
0.122
0.115
0.066
0.110
0.049
0.111
0.122
0.122
0.115
0.066
0.110
0.049
0.106
0.122
0.122
0.115
0.066
0.110
0.049
0.103
0.122
0.122
0.115
0.066
0.110
0.049
0.119
0.157
0.161
0.152
0.117
0.159
0.099
0.148
0.157
0.161
0.152
0.117
0.159
0.099
0.150
0.157
0.161
0.1S2
0.117
0.159
0.099
0.148
0.157
0.161
0.152
0.117
0.159
0.099
0.145
0.157
0.161
0.152
0.117
0.159
0.099
0.156
8
8
8
8
8
8 >
8
8
8
8
&
8
8
8
8
8
8
8
8
250
8
8
8
8
8
250
250
250
Z5U
250
250
250
250
250
250
250
250
222
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
-------
Table 13 (Continued)
00
O
8-Hour TWA Exposure ft/cal
Product
Automatic Transmission
Components
Friction Materials
Job Category*
(Saa Paper Products
Specialty Paper,
Section B.I)
Fiber Introduction/
Mixing
Forming
Finishing
Inspection/Packing
Scrap/Hast* Handling
Other
Total
Population
1
99
34
33
7
7
187
Pre-0.2 f/cc PELC
Geometric Mean
0.039
0.251 (71)
0.226 (301)
0.174 (336)
0.104 (63)
0.240 (18)
0.060 (68)
0.220
Arithmetic Mean
0.061
0.4S7
0.482
0.357
0.404
0.515
0.197
0.450
Post-0.2
Geometric Mean
0.037
0.122
0.122
0.115
0.066
0.110
0.049
0.115
f/cc PEL0
Arithmetic Mean
0.054
0.157
0.161
0.152
0.117
0.159
0.099
0.153
Duration
(hr/day)*
8 i
8
8
8
8
8
8
8
Frequency
(days/year)1
198
250
?sn
7«n
250
250
250
250
"Based on categorisation of job titles of workers monitored for exposure.
and ICF estimates aa described in the text. Population by Job category la estimated from the 1981 TSCA Section
«r.i« F"«7t»T7ttl0|'?? >rittaitl? "•"• °f th6 rwf 8-hour ™ «*>•«• <»•«••• »• nu«*>« «« ** point, i. given in parentheses. A. value.
corresponding to the total populations are calculated as weighted averages baaed on the number of workers exposed in each Job category.
"Geometric and arithmetic .wans of raw data after reducing all value* exceeding the 0.2 f/cc PEL to 0.2 f/cc. Data that are already at or below this value
remain unchanged. The values corresponding to the total populations are determined in the same manner ea the pre-0.2 f/cc PEL total exposure values.
™ff« ™ °* Tr" is 8 h™"/0-* »» •" «=•«•»• Mh«. no duration 1. provided. 8 hours/day Is assumed. Exposure, for 1... than 8 hours are
converted to 8-hour THAa, assuming zero exposure during periods when the worker is not handling asbestos.
».'««:,' ™f*r' to th* nuBlb»r ot day* annually that the workers are performing a task involving potential exposure to asbestos. The frequency is assumed to
be 250 days/year unless data for specific Job types indicate otherwise. frequency is assumed to
Sources: ICF Exposure Survey 1986-1987; ICF Market Survey 1986-1987; ICF estimates; HIOSH 1982c, 1984a, and 1985b; OSHA 1987.
-------
primary manufacture of friction products vary from company to company. All
companies use exhaust ventilation. Some companies use automatic bag-opening
machines; manual bag-opening is used by others. The level of automation
varies (IGF 1986b) . The use of automatic bag opening, emptying, and disposal
equipment can reduce asbestos exposure to well below the 0.2 f/cc PEL during
fiber introduction and mixing operations, according to a report by NIOSH
(1984a). '•
To estimate the projected post-0.2 f/cc PEL exposures, all exposure levels
exceeding 0.2 f/cc were reduced to 0.2 f/cc. As Table 13 shows, this reduces
the geometric and arithmetic mean TWA exposures to well below the 0.2 f/cc PEL
for all job categories. Many companies report exposures below 0.2 f/cc in all
job categories; therefore, it is likely that exposures can be reduced to this
level by means of improved engineering controls and housekeeping for most
workers. Respiratory protection may be required during some operations.
(2) Secondary Manufacture
Table 14 summarizes exposures for secondary processing of
friction products, including secondary manufacturing and brake rebuilding.
For secondary manufacturing, 1981 TSCA Section 8(a) data on population for
each friction product were adjusted to 1985 populations, as described above,
to obtain estimates of total population by product type. To estimate the
population by product type for automotive rebuilding, total employment from
OSHA (1986b) was used, and the ratio of population for rebuilding of each
friction product to total population for all friction product rebuilding was
assumed to be the same as determined for secondary manufacturing of friction
products from the 8(a) data. The 1981 TSCA Section 8(a) data (EPA n.d.) were
used to distribute the total population by job category for each friction
product for both secondary manufacture and rebuilding.
- 81 -
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Table 1*. Exposure Profile for Friction Product* — Secondary Manufacture and Rebuilding
oo
ho
6-Hour TWA , xuosure (f/cel
Product
Job Category*
Population
Pre-0.2
Geometric Mean
f/cc PELC
Arithmetic Mean
Post-0.2 f/cc PEL0
Geometric Mean
Arithmetic Mean
Duration
(hr/day)*
Frequency
(days/year)1
Secondary Manufacturing
Drum Brake Lining
Disc Brake Pads (Light
and Medium Vehicles)
Brake Blocks
Clutch Facings
Friction Materials
Processing
Other
Total
Processing
Other
Total
Processing
Other
Total
Processing
Other
total
Processing
Other
Total
949
988
1,937
166
101
267
a
8
16
36
12
48
25
2
27
0.016
0,011
0.014
0.018
0.011
0.015
0.018
0.011
0.015
0.018
0.011
0.016
0.016
0.011
0.017
(18)
(2)
(IB)
(2)
(16)
(2)
(18)
(2)
(18)
(?)
Automotive
Drum Brake Lining
Disc Brake Pads (Light
and Medium Vehicles)
Brake Blocks
Clutch Facings
Friction Mater
Processing
Other
Total
Processing
Other
Total
Processing
Other
Total
Processing
Other
Total
Processing
Other
Total
1,964
2.045
4.009
342
209
SSI
16
IZ
33
75
22
100
52
5
57
0.013
0.014
0.014
0.013
0.014
0.013
0.013
0.014
0.014
0.013
0.014
0.013
013
014
013
(44)
(?)
(44)
(?)
(44)
(8)
(44)
(8)
(44)
(8)
0.190
0.017
0.102
0.190
0.017
0.125
0.190
0.017
0.104
0.190
0.017
0.147
0.190
0.017
0.177
Rebuilding
0.033
0.063
0.058
0.033
0.063
0.037
0.053
0.063
0.038
0.053
0.063
0.056
f )
0.015
0.011
0.013
0.015
0.011
0.013
0.015
0.011
0.013
0.013
0.011
0.014
0.015
0.011
0.015
0.013
0.014
0.014
0.013
0.014
0.013
0.013
0.014
0.014
0.013
0.014
0.013
0.013
0.014
0.013
0.080
0.017
0.048
0.060
0.017
0.056
0.080
0.017
0.049
0.080
0.017
0.064
0.060
0.017
0.075
0.043
0.037
0.051
0.043
0.057
0.030
0.045
0.057
0.051
0.0.45.
0.057
0.048
0.045
0.057
0.046
8
8,
8
8
8
8
8
8
6
J
8
8
8.
8
6
8.
8
8
fi
8
8
fi
6
8
8
8
8
8
8
250
250
**^v
250
250
250
XIXpS,
250
250
8250
jcnm
250
250
250
SSJSiX.
250
250
250
xzs
250
250
230
sxs
250
250
250
XUUL
250
250
230
250
2SO
250
250
250
250
250
-------
Table 1* (Continued)
"Based on categorization of job titles of workers monitored for exposure.
Secondary manufacturing population totals estimated from 1981 TSCA Section 8(a) populations (RTI 1985) adjusted to 1985 populations by multiplying by the
ratio of 1985 primary production (ICF Market Study 1986-1987) to 1981 primary production (EPA 1986b, midpoints used). Automotive rebuilding population total
from OSHA (1986b). Population by job category estimated from 1981 TSCA Section 8(a) data (EPA n.d.).
°These values present geometric and arithmetic means of the raw 8-hour TWA exposure data. The number of data points is given in parentheses. The values
corresponding to the total populations are calculated as weighted averages based on the number of workers exposed in each Job category.
Geometric and arithmetic means of raw data after reducing all values exceeding the 0.2 f/cc PEL to 0.2 f/cc. Data that are already at or below this value
remain unchanged. The values corresponding to the total populations are determined in the same manner as the pre-0.2 f/cc PEL total exposure values.
"The effective duration of exposure is 8 hours/day in all cases. Where no duration is provided, 8 hours/day is assumed. Exposures for less than 8 hours are
converted to 8-hour THAs, assuming zero exposure during periods when the worker is not handling asbestos.
frequency refers to the number of days annually that the workers are performing a task involving potential exposure to asbestos. The frequency is assumed to
be 250 days/year unless data for specific Job types indicate otherwise. Some companies may not do asbestos-related work full-time, but few data are available
on frequency to make a better estimate.
'included with automotive rebuilding because the rebuilding process would be similar to rebuilding of automotive products.
Sources: ICF Exposure Survey 1986-1987; ICF Market Survey 1986-1987; ICF estimates; HIOSH 1982d, 198
-------
Disc brakes for heavy vehicles and automatic transmission components are
not included in Table 14 because production is very small compared to other
friction products; and, therefore, less than one full-time employee would be
exposed.
Some secondary manufacturers of friction products may carry out
manufacturing processes on a part-time basis (e.g., see N10SH 1985c); others,
however, operate on a full-time basis (ICF Exposure Survey 1986-.1987). We do
not have enough data to determine whether the average frequency of exposure is
less than 250 days per year, so we used the 250 days/year default value.
As Table 14 shows, geometric mean, 8-hour TWA exposures are well under the
0.2 f/cc PEL for secondary manufacturing of friction products and brake
rebuilding, although in individual cases, exposures exceeded the PEL. The
arithmetic mean exposure for "processing" is close to the PEL because several
raw data exposure points exceed 1 f/cc.
Respirators or dust masks may be required for some job categories in some
facilities (ICF Exposure Survey 1986-1987). Engineering controls such as dust
collection systems and local exhaust ventilation may also be used, -"
companies may not use these controls (ICF Exposure Survey 1986-i:
1982d).
The post-0.2 f/cc PEL was estimated by reducing all exposure levels
exceeding 0.2 f/cc to 0.2 f/cc and determining new geometric and arithmetic
mean. It is likely that most facilities will be able to achieve the 0.2 f/cc
level through engineering controls and improved housekeeping, since in most
cases, exposures are already below this level.
5. Textiles
a. Product Descriptions
Asbestos fiber is used to provide resistance to fire and heat in
textile products. Historically, asbestos textiles have been used in a wide
- 84 -
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range of produc- jut many of the traditional products are no longer in
production. Subs'itute fibers have taken up the bulk of the market for
electrical and thermal insulation, fire resistant materials, and protective
clothing.
The products that continue to be made with asbestos textiles are:
• friction products;
• packings and gaskets; and
• specialty products.
Friction materials account for the majority of the asbestos textile products
made from asbestos yarn and include woven brake blocks and clutch facings.
Typically woven brake blocks are used in large industrial equipment such as
oil well drilling rigs and cranes.
Packings and gaskets made from asbestos textiles include both yarn and
cloth products. Asbestos yarn products, braid and rope, are used extensively
in pump and valve packings and as seals for oven doors, boilers, and furnaces.
Asbestos cloth is used to manufacture manhole and flange gaskets as well as
seals in incinerator (hot-air) piping, nuclear power plant cooling water
towers, and distillation columns.
Specialty products are also made from asbestos cloth and asbestos yarn.
It is often difficult to find substitute materials for these specialized
applications, but products of this type are usually produced in relatively
small volume (less than 5,000 pounds).
Some products made from asbestos textiles that can be classified as
specialty products are:
• mantles for gas lanterns (yarn);
• wicks for catalytic heaters (yarn);
• rotor vanes for pumps and compressors used in air tools
(cloth);
- 85 -
-------
• ring type seals for valve' and compressor plat^ .m); and
• bearings for high temperature applications requ..ing water
lubrication (cloth).
Primary manufacturing of asbestos textile materials produced 1,125 tons of
asbestos thread in 1985, consuming 558 tons of asbestos fiber and potentially
exposing 78 workers to asbestos (ICF Market Survey 1986-1987). An additional
527.6 tons of asbestos textile mixture was imported in 1985. Secondary
fabricators of asbestos thread, yarn, cloth, and other textiles' employ
approximately 208 asbestos workers (ICF Market Survey 1986-1987).
b. Process Descriptions
(1) Primary Manufacture
Asbestos textile products can be classified into two main
product areas: asbestos cloth and asbestos yarn. While there are a wide
variety of asbestos textile applications, each product will be assigned to one
of these two major categories for the purposes of simplicity.
The manufacture of asbestos textiles shares characteristics common f~
textile production. In particular, asbestos textiles are produc
asbestos fibers by standard textile production techniques. Asbestos ri^-
can be blended with other types of fibers and often carrier yarns are added to
asbestos yarns to give the resulting textile products added tensile strength.
The manner in which asbestos fibers are processed into asbestos yarn and cloth
products includes the following steps: milled fiber storage, pneumatic
grinding (addition of fibers), cording and combing, matting (mat and roving),
spinning (for yarn or cord), and braiding or weaving.
There are two basic variations employed in asbestos textile manufacturing
the conventional and wet processes. The methods employed in producing
asbestos textiles by each of these methods is described below, although most
textiles are manufactured by the conventional process.
- 86 -
-------
In the conventional process, raw asbestos fibers of various grades are
blended and mixed, with the composition of the blends and fixing of the
formulation being governed by the fiber characteristics, manufacturing and
finished product requirements, and intended use. The different grades of
asbestos fiber received are moved to the rear of the blender where they are
mixed according to the requirements specified for the finished product. The
selected fiber sizes then enter a hopper. When filled, the hopper delivers
the blended material to the carding operation.
The carding operation combs the fibers into a relatively parallel
arrangement called a fiber mat. This mat is pressed and layered into a lap
consisting of alternating perpendicular arrangements of fiber mats. The lap
is then separated into thin, continuous ribbons called roving. Cotton, rayon
or other material may be added at this stage to strengthen the roving.
Roving, which has been mechanically twisted and spun to give it tensile
strength, forms a single yarn. This yarn may be twisted with other single
yarns, wire or other material to produce plied yarn which can be coated to
/•
produce thread or treated yarns. Plied yarns may be woven to produce fabric,
sleeving, or tape. Alternately, plied yarns may be twisted to form wicking
and twisted rope, or braided to form braided rope or sleeving.
The conventional process employs either the dry or damp method. These two
methods are identical except that during the damp method, the yarn is
moistened either by contact with water on a roller or by a mist spray. This
moistening of the yarns reduces the amount of fiber that becomes airborne and
also aids the processing of fibers into yarn.
The wet process is based on forming single filament fibers by extrusion.
The process consists of making a gelatinous mixture of fine asbestos fiber in
water with a volatile dispersant. The mass is then extruded through small
dies to form asbestos thread. The extruded thread is spun to form yarn which
- 87 -
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is fabricated into various plied yarn products as in the conventional process.
The textile products formed using this wet technique tend to hold asbestos
fibers better than those produced by the conventional processes, thus reducing
workplace fiber levels, but the yarn formed has the disadvantage of poor
adsorption and impregnation characteristics.
(2) Secondary Manufacture
Asbestos cloth and yarns are used by secondary textile
manufacturers to produce fire and heat resistant materials and electrical
insulation. Specific processes primarily involve cutting of asbestos cloths
and sewing with asbestos thread.
c. Exposure Profile
The total population is based on the ICF Market Survey (1986-1987)
The distribution of the total number of workers exposed into specified job
categories is based on the 1981 TSCA Section 8(a) data (Hendrickson and Doria
1983).
For secondary manufacturing of textiles, the total population -
disaggregated into job categories. This total population value is based on
data from the ICF Market Survey (1986-1987). Some of the companies surveyed
did not disclose the number of workers exposed. The worker population for
these companies is estimated by using the ratio of population to amount of
asbestos mixture consumed for the other companies.
Exposure levels for asbestos textile operations are exhibited in Table 15
These exposure levels are based on the raw monitoring data. The . "_ 3
indicate that levels are highest during the carding and twisting operations
and lowest during preparation and winding. Spinning and waste handling also
have high potential for producing airborne asbestos.
Asbestos textiles are manufactured using either conventional dry or damp
processing, or a wet process in which the raw asbestos is dumped directly int<
- 88 -
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Table IS. Exposure Profile for Textiles
00
vo
8-Hour TWA Exposure (f/cc)
Product Job Category*
Population
Pre-0.2 f/cc PELC
Geometric Mean
Arithmetic Mean
Post-0.2
Geometric Mean
f/cc PEL0
Arithmetic Mean
Duration
(hr/day)a
Frequency
(days/year)f
Primary Manufacturing
Textiles Preparation
Carding
Twisting
Winding
Total
16
30
30
2
78
0.168 (7)
0.402 (48)
0.613 (39)
0.217 (17)
0.430
0.241
0.565
0.730
0.260
0.554
0.126
0.184
0.197
0.161
0.177
0.149
0.187
0.198
0.169
0.183
8
8
8
a
8
240
240
240
240
240
Secondary Manufacturing
Textiles H/A
208
0.251 (12)
0.420
0.146
0.157
B
0250
"job categories are based on a concise categorization of the job titles.
Estimation of total population is described in the text. Population by Job category is estimated from the 1981 TSCA Section 8(a) data (Bendrickson and Dorla
1983).
°These values represent geometric and arithmetic means of the raw 8-hour TWA exposure data. The number of data points is given in parentheses. The value
corresponding to the total population is calculated as a weighted average based on the number of workers exposed in each Job category.
These post-0.2 f/cc PEL exposure values are calculated directly from the raw monitoring data. Each 8-hour THA exposure value that is above 0.2 f/cc is
reduced to exactly 0.2 f/cc. Oats that are already at or below this value remain unchanged. The value corresponding to the total population is determined in
the same manner as the pre-0.2 f/cc PEL total exposure value.
*The effective duration of exposure is 8 hours/day in all cases. Where no duration is provided, 8 hours/day is assumed. Exposures for less than 8 hours are
converted to 8-hour TWAs, assuming tero exposure during periods when the worker is not handling asbestos.
'frequency refers to the number of days annually that the workers are performing a task Involving potential exposure to asbestos. The frequency is assumed to
be 240 days/year for primary manufacturing. Secondary manufacturing is assumed to have a 250 day/year frequency.
Sources: ICF Exposure Survey 1986-1987; OSHA 1987; HIOSH 1980a, 1980b; ICF Market Survey 1986-1987.
-------
a slurry tank with water and chemicals; the process utilized can greatly
influence the exposure levels. Dust release is much greater during
conventional dry processing than damp processing, in which a roller or mist
spray is used to apply moisture to the yarn.
Exposure is assumed to be reduced to post-0.2 f/cc PEL levels via
application of available engineering controls. As in other industries, the
primary engineering control in textile plants using dry methods is LEV. It is
typically used at such stages as bag opening, fiber introduction, willowing,
blending, carding, and winding. The carding operation may be isolated in
addition to having exhaust ventilation. Either LEV or general exhaust
ventilation with humidification may be employed during the spinning operation.
Nevertheless, respirators, are usually required in the spinning and carding
areas.
Wet processing, such as a damp loom for weaving, can great1%
exposure. But this is not viable in many cases because wet processing -
changes the nature of the textile. Apparently, most dry asbestos textile
manufacturers using state-of-the art controls can achieve 0.2 f/cc exposure
levels. Dry mechanical manufacturing, however, seems to present difficulties,
and certain operations (e.g., carding, spinning and twisting) require
supplemental respirator usage to reduce excessively high exposure levels.
The pre-0.2 f/cc PEL exposure level determined for secondary manufacturing
of textiles is substantially lower than for primary manufacturing; however,
further reduction is also required for this sector to meet tht ' level.
This reduction is assumed to occur by techniques similar to those -.
primary manufacturing. The dry mechanical operations involved in this sector
have high potential for exposures above 0.2 f/cc. The specific processes of
concern are cutting of asbestos fibers and sewing with asbestos thread.
- 90 -
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6. Sh?st: Gaskets and Packing
a. -roduct Descriptions
Gaskets are devices which are used to seal the space between two
non-moving (usually metal) surfaces (OSHA 1986b). They are used to prevent
leaks of liquids or gases in a system, often under conditions of high
temperature and pressure. Because of these requirements, asbestos is a
desirable ingredient in gaskets due to its heat and chemical resistance as
well as its strength (Chemical Engineering 1986). Asbestos gaskets are used
in large pipes in oil refineries and nuclear power plants, and in automotive
engine blocks and oil pans.
Packing materials are very similar to gaskets except that packings are
placed between a moving and a non-moving surface (Freimanis 1981). Packings
are used in pumps, turbines, shafts, and other similar places. The chemical
process and electric power industries are among the greatest users of packings
(Chemical Engineering 1986).
According to the ICF Market Survey (1986-1987), primary producers of sheet
gaskets produced 3.5 million square yards of gasketing material in 1985,
consuming 5,301 tons of asbestos and exposing a total of 163 employees to
asbestos (ICF Market Survey 1986-1987).
Packing manufacturers produced 4 tons of asbestos packing material in
1985, consuming 2.5 tons of asbestos fiber and exposing about 5 employees to
asbestos (ICF Market Survey 1986-1987).
Secondary processors of sheet gaskets have an estimated total of more than
878 employees exposed to asbestos. Total population exposed to asbestos was
estimated from the number of employees reported in the ICF Market Survey
(1986-1987) and an estimate based on the number of employees per square yard
of asbestos mixture consumed for those companies for which employment was not
reported. Due to gaps in the ICF Market Study (1986-1987) data, the estimated
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population TOT secondary manufacture of sheet Baskets ^er limit . 1981
TSCA Section 8 (a) data are not adequate to rerlne
Secondary -processing of asbestos pac
(ICF Market Surwey 198fi-19£7>. -
.*«
"b. Process Deseri-Dtlona
ary ManufacCugB
The Tsixtare-nsefl
^ * -* -af-^.j** „ ,,- .
asbestos. The asbestos Is -sized -wttS TSU
metals^ anfl an organic soTveot (e.^.J tetrsZluoroedkylme (lFt.)l» __ aad
together into a rather homogeneous jsheet (TrelmaniB 19B1). 'Vhen the
. 7 -••*-
i mLx and thickness axe .achieved, the sliaet Is cut to « predetermined
length and vidrh (ICF 15B7) . flsjs/ »«nirf»rn«Sqg
Tollitig^iMd vejvijy «f £flsMX nifif gr fafTr ^s^hcgro
-- .••*•- '."
hag-slitters in acate pracesses (JUUftl 19B4c) .
Manufacture of asbestos packings is siailar to that of gaskets. «-'
is rolled into a honogenops mixture with plastic, rubber, neta1
other materials. 'Aiitaaateff^raidiss jfi^<»oeefte are used to strengthen the
* . ~
entire paoV^Tip mat-»->H m\ rmnptHs-j f jam if nenaT^y 7Q £0 *99 SArcent or aoce
asbestos, depending xm the "heat resistance needed (Treljnanis T991).
Prijiary manufacturers of sheet gaskets and packing may pre-form the
Materials to fit a predetermined shape needed "by the user.." This; process1 Is
~T - ; - • •"•••-.*••_•<..•
"frequently carried out l»y seconAary nuniifai
Secondary manufactnrrrs -of sheet gaskets and packing cut and
shape sheet gasketing and packing material to .meet user specific
uses such as automotive examine blocks, oil pans, and certain kinds of v<^
In some rases , a gasket can be irot into Its -proper shape using a sharp knife
(OSHA 1966b) .
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"xposure Profile
(1) Primary Manufacture
Table 16 presents geometric and arithmetic mean, 8-hour TWA
exposure levels and populations exposed by job category for primary
manufacture of sheet gaskets and packing. Population by job category was
estimated from the 1981 TSCA Section 8(a) data (Hendrickson and Doria 1983).
There are few exposure data available specific to packing; because
manufacturing processes are similar for sheet gaskets and packing, the mean
exposure levels for sheet gaskets are assumed to apply to packing manufacture
as well.
From the limited data available, the geometric mean, 8-hour TWA exposure
level is well below the 0.2 f/cc PEL for all job categories, although
exposures may exceed the PEL in individual cases. The arithmetic mean
exposure exceeds the PEL for the "other" job category. Some companies may
require use of respirators for some operations, and there are likely to be
engineering controls in place (ICF Exposure Survey 1986-1987, NIOSH 1984c).
To estimate exposure levels under the 0.2 f/cc PEL, all reported exposures
exceeding 0.2 f/cc were reduced to the 0.2 f/cc level. New geometric and
arithmetic means are determined for each job category. There were few
reported exposures exceeding 0.2 f/cc for sheet gasket and packing
manufacture. The highest exposures reported are for unspecified "operators",
placed in the "other" job category; it is not known what type of operation was
involved at the time the monitoring was performed.
Since in most cases current exposures are well below 0.2 f/cc, it is
likely that all facilities can achieve exposure levels below 0.2 f/cc by use
of engineering controls and good housekeeping practices.
- 93 -
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Table 16. Exposure Profile for Sheet Gaskets and Packings
vo
8-Hour TWA Exposure (f/cc)
Product
Job Category*
Population
Pre-0.2 f/cc PELC
Geometric Mean
Arithmetic Mean
Post-0.2
Geometric Mean
f/cc PEL"
Arithmetic Mean
Duration
(nr/day)*
Frequency
(days/year)1
Primary Manufacturing
Sheet Gaskets
Packing
Fiber Introduction
Mixing
Molding
Finishing
Other
Total
Fiber Introduction
Mixing
Molding
Finishing
Other
Total
62
11
10
38
42
163
1
1
1
1
I
5
0.044 (9)
0.062 (8)
0.022 (7)
0.015 (2)
0.035 (12)
0.035
0.044 (9)
0.062 (8)
0.022 (7)
0.015 (2)
0,035 (121
0.036
0.081
0.164
0.045
0.116
0.363
0.165
0.061
0.164
0.045
0.116
0.363
0.154
0.043
0.049
0.022
0.014
0.024
0.030
0.043
0.049
0.022
0.014
0.024
0.030
0.076
0.087
0.045
0.101
0.072
0.080
0.076
0.087
0.045
0.101
0.072
0.076
8'
8
8
8
8
8
8
8
8
8
8
8
250
250
250
250
250
250
250
250
250
250
250
250
Secondary Manufacturing
Sheet Gaskets
Packing
Processing
Other
Total
Processing
Other
Total
571+
307+
878+
16
9
25
0.061 (136)
0.127 (2)
0.084
0.061 (136)
0.127 (2)
0.085
0.128
0 . 128
0.128
0.128
0.128
0.128
0.055
0.127
0.080
0.055
0.127
0.081
0.094
0.128
0.106
0.094
0.128
0.106
8
fi
8
8
8
8
250
250
250
250
250
250
'Based on categorization of job titles of workers monitored for exposure.
bTotal population based on ICF Market Survey and ICF estimates as described in the text. Population by Job category is estimated from the 1981 TSCA Section
8(a) data (Bendrickson and Dorla 1983, EPA n.d.).
cThese values present geometric and arithmetic means of the raw 8-hour TWA exposure data. The number of date points is given in parentheses. The values
corresponding to the total populations are calculated as weighted averages based on the ntxofaer of workers exposed in each job category.
dGeometric and arithmetic means of raw data after reducing all values exceeding the 0.2 f/cc PEL to 0.2 f/cc. Data that are already at or below this valui.
remain unchanged. The values corresponding to the total population are determined in the same manner aa the pre-0.2 f/cc PEL total exposure values.
eThe effective duration of exposure is 8 hours/day in all cases. Where no duration <« provided, 8 hours/day is assumed. Exposures for less than 8 hours are
converted to 8-hour TWA*, assuming zero exposure during periods when the worker I handling asbestos.
Frequency refers to t h > .mitber of days annually that the workers are performing
be 250 days/year tin let • « for specific Job types indicate otherwise. Frequen<
Sources: ICF Exposuiu Sutvey 1986-1987, ICF Market Survey 1986-1987, ICF eatim*
volving potential exposure to asbestos. The frequency la assumed to
•omewhat from company to company.
4c, OSHA 1987.
-------
!2) Secondary Manufacture
Exposure data for secondary manufacturing of sheet gaskets and
packings are also presented in Table 16. Total population was estimated from
the ICF Market Survey (1986-1987) as discussed earlier; population by job
category was estimated from the 1981 TSCA Section 8(a) data (EPA n.d.).
Geometric and arithmetic mean exposures are well below the 0.2 f/cc PEL
for secondary manufacturing. The highest reported exposures are for
unspecified laborers (placed in the other category); it is not clear what
operations are involved in these cases.
No mandatory use of respirators was reported by respondents to the ICF
Exposure Survey (1986-1987); however, engineering controls such as closed
process units in some areas and exhaust ventilation were reported.
To estimate exposures under the 0.2 f/cc PEL, all exposure levels
exceeding 0.2 f/cc were reduced to the 0.2 f/cc level and new geometric and
arithmetic means are determined. The estimated, post-0.2 f/cc exposure level
is not significantly lower than the current level. Many companies report
exposure levels well below 0.2 f/cc; it is likely that all companies can
achieve these levels through the use of engineering controls and improved
housekeeping practices.
7. Roof Coatings. Non-Roofing Coatings. Missile Liner and
Sealant Tape
a. Product Descriptions
Roof coatings, non-roofing coatings, missile liner, and sealant
tape are produced using similar methods and are, therefore, grouped together
in this section.
Roof coatings containing asbestos are used to provide water, weather,
heat, and corrosion resistance to roofs. Roof coatings may also be applied to
sidewalks, concrete foundations, and brick. These coatings are asphalt-based
- 95 -
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and thinned with solvents; asbestos fibers, which matte up 7 to 10 percent of
the coating by weight (ICF 1987), provide body and reinforcing properties.
Roofing, tile, and flashing cements, also asphalt-based and solvent-thinned,
are used to repair roofs, seal around projections such as vent pipes and
chimneys, and bond horizontal and vertical surfaces. These products contain
15 to 20 percent asbestos by weight (ICF 1987).
Coatings for non-roofing applications include the following:
• Specialty coatings;
• Epoxy-based adhesives for automotive and construction use;
• Caulks and joint compounds;
• Sealants for equipment and building construction; and
• Vehicle undercoatings.
Missile liner is a rubber compound used to coat Che interior of rocke-
motors. Its main function is to insulate the outer casing of t'-
the intense heat generated while the rocket fuel is burned (ICF 1987).
Sealant tape is made from a semi-liquid mixture of butyl rubber and
asbestos. Asbestos usually constitutes 20 percent by weight of the mixture.
On exposure to air, the sealant solidifies forming a rubber tape. The tape i
used for sealing building windows, automotive windshields, and mobile home
windows, and in the manufacture of parts for the aerospace industry and
insulated glass (ICF 1987).
Table 17 shows production, asbestos consumed, and employees exposed to
asbestos for the coating-type products discussed in this sect! ~ number
of employees exposed to asbestos for these products was estimated from the
total reported in the ICF Market Survey (1986-1987) and an estimate based on
the average number of employees per ton of asbestos consumed for those
companies for which employment was not reported.
- 96 -
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Table 17. Production and Employment for Coating Type Products
Product
Total Production3
Asbestos
Consumption^
(tons)
Total
Population
Exposed
to Asbestos0
Roof Coatings
Non-Roofing Coatings
Missile Liner
Sealant Tape
57.2 million gallons 22,215
8.1 million gallons 2,083
4.6 thousand tons 699
423 million feet 1,660
438
497
380
134
a!985 production, excluding production by companies no longer producing
asbestos products.
°1985 consumption, excluding consumption by companies no longer producing
asbestos products.
Population based on ICF Market Survey (1986-1987) (1985 employment,
excluding companies no longer producing asbestos products) and estimates
described in the text for companies with no population figures reported.
Sources: ICF Market Survey 1986-1987, ICF estimates.
- 97 -
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In addition, secondary producers of non-roofing -eatings consumed a tota
of 25.4 gallons of asbestos mixture in 1985; 76 employees were exposed to
asbestos (ICF Market Survey 1986-1987).
b. Process Descriptions
Asbestos roof coatings and cements are normally manufactured in
batches. Asbestos fibers are dumped into a hopper or fluffing machine and tl
fibers are fluffed; the fibers are then transferred to a mixer and combined
with other dry ingredients. Asphalt and solvents are added, and all the
ingredients are mixed. The product is then packed in containers. Bags of
fiber are generally opened and added manually (ICF 1986b), although some
companies may use bag-opening machines (NIOSH 1983c); the rest of the proces-
is automated (ICF 1986b).
Manufacture of non-roofing coatings, missile liners, and sealant
carried out using processes similar to that described for roc
Coatings and related products are usually shipped directly for use; u._
is little likelihood of secondary processing even though two secondary
processors were identified in the ICF Market Survey (1986-1987).
c. Exposure Profile
Table 18 summarizes geometric and arithmetic mean exposure levels
for the primary manufacture of coatings and related products. In most cases,
the exposure data could not be broken down by specific product, and the data
are limited for missile liner and sealant tape. Since these products are
manufactured using similar processes, data related to all typ -<-ngs
are combined. The geometric and arithmetic mean exposure levels - job
category are assumed to apply to all coating products. There are no e.\. :?
data for secondary processing of coatings; therefore, secondary processing is
not included in the table. In addition, it is not clear what type of
operations would be involved in secondary processing.
- 98 -
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Table 18. Exposure Profile for Coatings -- Primary Manufacture
8 -Bout TWA Exposure (f/cc)
Product Job Category*
Roof Coatings Fiber, Preparation/
Fiber Introduction
Mixing
Other
Total
Non-Roof Coatings Fiber Preparation/
Fiber Introduction
Mixing
Other
Total
Missile Liner Fiber Preparation/
Fiber Introduction
Mixing
Other
Total
i
Sealant Tape Fiber Preparation/
vo Fiber Introduction
Mixing
Other
Total
Population
298
79
_il
438
338
20
139
497
2S8
15
12Z
380
91
5
_38
134
Pre-0.2
Geometric Mean
0.040 (12)
0.047 (50)
0.082 (34)
0.047
0.040 (12)
0.047 (50)
0.082 (34}
0.052
0.040 (12)
0.047 (50)
0.082 (34)
0.052
0.040 (12)
0.047 (50)
0.082 (34)
0.052 x
f/cc PELC
Arithmetic Mean
0.331
0.490
0.946
0.445
0.331
0.490
0.946
0.509
0.331
0.490
0.946
0.510
0.331
0.490
0.946
0.511
Post-0.2
Geometric Mean
0.024
0.029
0.04B
0.028
0.024
0.029
0.048
0.031
0.024
0.029
0.048
0.031
0.024
0.029
0.048
0.031
f/cc PEL"
Arithmetic Mean
0.103
0.104
0.114
0.105
0.103
0.104
0.114
0.106
0.103
0.104
0.114
0.106
0.103
0.104
0.114
0.106
Duration
(hr/day)e
8
8
a
8
8
8
8
8
8
8
fi
8
8
8
fi
8
Frequency
( days /y ear )f
250
250
250
250
200
200
200
200
200
200
200
200
200
200
200
200
"Based on categorization of job titles of workers monitored for exposure.
Total population baaed on ICF Market Survey and ICF estimates as described in the text. Population by job category la estimated from the 1981 TSCA Section
8(a) data (Hendrickson and Doria 1983).
°The values present geometric and arithmetic means of the raw 8-hour TWA exposure data. The number of data points is given in parentheses. The values
corresponding to the total populations are calculated as weighted averages based on the number of workers exposed in each Job category.
Geometric and arithmetic means of raw data after reducing all values exceeding the 0.2 f/cc PEL to 0.2 f/cc. Data that are already at or below this value
remain unchanged. The values corresponding to the total populations are determined in the same manner as the pre-0.2 f/cc PEL total exposure values.
"The effective duration of exposure is 8 hours/day in all cases. Mhere no duration is provided, 8 hours/day la assumed. Exposures for less than 8 hours are
converted to 8-hour THAa, aasumlng zero exposure during periods when the worker is not handling asbestos.
fFrequency refers to the number, of days annually that the workers are performing a task involving potential exposure to asbestos. The frequency is assumed to
be 250 days/year unless data for specific job types indicate otherwise. It is likely that non-roofing coatings, missile liner, and sealant tape are produced
on a part-time basis, but insufficient data are available to determine average frequencies.
Sources: ICF Exposure Survey 1986-1987; ICF Market Survey 1986-1987; ICF estimates; NIOSH 1981b, 1982e, 1983c, 1984d, and 1984e; OSHA 1987.
-------
The total number of workers exposed to asbestos during manufacture of eac
type of coating product was estimated from the ICF Market Survey (1986-1987)
and asbestos consumption, as described earlier. The number of workers per jo
category was estimated from the 1981 TSCA Section 8(a) data (Hendrickson and
Doria 1983).
For non-roofing coatings and sealant tape, it is likely, based on the ICF
Exposure Survey (1986-1987) that workers are not exposed full-time.
Respondents reported production of these products 10 to 208 days per year.
There were insufficient data to determine an average frequency, but it seems
likely that it is less than 200 days per year. It is likely that this is als
true for missile liner, based on the high ratio of employees to productio*-
asbestos consumption (see Table 17).
Few data are available on frequency for production of roof coaL*tlgs;
survey respondent reported production frequency of 100 days per year (ICF
Exposure Survey 1986-1987). Roof coatings are produced in larger quantities
than the other types of coatings (ICF Market Survey 1986-1987); therefore,
production is more likely to be full-time, although some companies are
probably part-time producers.
Geometric mean, 8-hour TWA exposure levels are below the 0.2 f/cc PEL for
all job categories for coating products, although individual exposures may
exceed the PEL. The arithmetic mean exposure levels for each job category
exceed the PEL due to high exposures reported.
Mandatory use of respirators or masks during coatings manuf- —••.
reported by all respondents to the ICF Exposure Survey (1986-198/
processes were also reported. OSHA (1986a) reports that fluffing and m~—.,
operations are kept under negative pressure, and housekeeping around these
operations is continuous.
- 100 -
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Projectec., ccst-0.2 f/cc PEL exposures were estimated by reducing all
exposures thac exceeded 0.2 f/cc to the level of the PEL.
8. Asbestos-Reinforced Plastics
a. Product Description
Asbestos fibers are added to a wide variety of plastics to improve
stiffness, strength, processability, and provide corrosion and heat
resistance. The asbestos acts as both a mineral and fibrous binder carrier
with reinforcing action. Asbestos-reinforced plastics are used in the
electronic, automotive, and printing industries with applications in
appliances, utensils, tools, automobiles (in the ignition, transmission, and
wiring systems), wiring devices, electrical switch gears, and communication
and electronics equipment. Other uses include floor tiles, packing, and
gaskets, but these products are not discussed in this section.
The amount of asbestos used in plastics varies widely from product to
product, but it is relatively small compared to other product categories.
Asbestos is now used only with phenolic resins, although traditionally
asbestos has been used with a variety of other plastic resins including
polyester, urea, diallyl phthalate, vinyl epoxy, polypropylene, and nylon.
Primary manufacturers produced 4,250 tons of asbestos-reinforced plastics
in 1985. These companies consumed 636.1 short tons of asbestos fiber in 1985
(ICF Market Survey 1986-1987). In addition, 127.5 tons of reinforced plastic
was imported in 1985, and several companies perform secondary fabrication of
reinforced plastics (ICF Market Survey 1986-1987). There are 138 and 456
asbestos workers involved in the primary and secondary manufacturing of
plastics, respectively.
- 101 -
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b. Process Descriptions
(1) Primary Manufacture
The processing of asbestos-reinforced plastics may be
implemented by either a primary or a secondary manufacturer. Primary
processors introduce raw asbestos fibers and dry mix it with catalysts and
other additives. The mixture is transferred via sealed containers or vacuum
conveyors to resin formation equipment. Various types of equipment can be
used in this processing step, but in general the resin is formed by either
extrusion or internally heated Banbury mixing. Both processes result in
pellets, powders, or some similar product which is known as "preform." The
resin is drummed and employed in subsequent processes to form the end produr-
About 30 percent of primary processors fabricate the end products on-s-'
(Versar 1983). The remaining 70 percent of the plastic preforrr
packaged and sold to secondary manufacturers (Versar 1983); these ta,.
are usually remote from the primary processing facilities.
(2) Secondary Manufacturing
At secondary manufacturing locations asbestos-reinforced
plastic, or preform, is received by railcar or truck and is transferred to
storage areas and forming process areas by forklifts. The actual formation oi
an end-product is accomplished by rerneIting the preform and then submitting it
to rolling, molding, stamping, or pressing. Dust control equipment used
during these steps includes exhaust hoods leading to the fabric filters and
partial enclosure of process vacuuming equipment.
After forming the desired product, it is then cured. This is normally
accomplished in an enclosed area furnished with a ventilating system. When
air-curing processes are used, hoods and local enclosures are provided. Final
product characteristics, such as strength and stiffness, are partially
controlled by the time and temperature conditions during curing.
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After curing, the product is finished by drilling, grinding, machining or
sawing, depending on the end use of the product. Asbestos dust is released
when the plastic products are finished. Hand tools employ local exhaust
systems vented through a central fabric filter. Larger, stationary machines
also utilize local exhausts near the surface being finished, these are often
supplemented with hoods over the finishing machines themselves. In summary,
the main steps in secondary manufacturing consist of (1) resin receiving and
storage, (2) resin introduction, (3) forming, (4) curing, and (5) finishing.
As a final step, the asbestos-reinforced plastic product is packaged and
shipped to the consumer.
c. Exposure Profile
Due to the absence of monitoring data for primary manufacturing of
asbestos-reinforced plastics, the estimates for pre- and post-0.2 f/cc PEL
exposure levels are taken directly from OSHA's final regulatory impact
analysis (OSHA 1986b). The total exposed population is obtained from the ICF
Market Study (1986-1987), and the population distribution among job categories
is based on 1981 TSCA Section 8(a) data (Hendrickson and Doria 1983). Table
19 presents the exposure profile for this sector. Worker exposures during the
manufacture of asbestos-reinforced plastics are below 0.2 f/cc for several
operation categories. High exposure areas occur, however, in dry finishing
operations.
Exposure data are available for secondary manufacturing from two NIOSH
studies. Two personal samples collected for asbestos in the first NIOSH study
showed concentrations of 0.034 f/cc and 0.042 f/cc for operators working at
the standard injection molding line and at the HK standard compression molding
line, respectively (NIOSH 1983a). While these samples are below the new OSHA
PEL (i.e., 0.2 f/cc), higher exposures to asbestos may occur during the
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Table 19. Exposure Profile for Asbestos-Reinforced Plastics
Product
Job Category*
Population
Pre-0.2
Geometric Mean
8-Hour
f/cc PELC
Arithmetic
TWA Exposure (f/cc)
Post-0.2
Mean Geometric Mean
f/cc PELC
Arithmetic Mean
Duration
(hr/day)d
Frequency
(days/year)*
Primary Manufacturing
Asbestos-Reinforced
Plastics
Fiber Introduction
Wet-Mechanical
Operations
Dry-Mechanic al
Operations/
Finishing
Other
Total
35
4
12
_§Z
138
N/A
N/A
N/A
N/A
N/A
0.288
0.007
0.355
0.400
0.356
N/A
N/A
N/A
N/A
N/A
0.048
0.007
0.145
0.060
0.063
8
8
8
a
8
250
250
250
250
250
Asbsstos-Relnforced Plastics N/A
456
Secondary Manufacturing
0.120 (3) 0.423
0.066
0.092
250
N/A - Not Available.
*Job categories are based on the categorication presented by OSHA (1986b).
bThe total population is based on the ICF Market Survey (1986-1987). The distribution of the total number of workers exposed into specified job categories is
based on the 1981 TSCA Section 8(a) data (Bendrlckson and Ooria 1983).
cThe values for primary manufacturing are taken directly from OSHA's final regulatory impact analysis (OSRA 1986b). Ho other exposure information was
available for primary manufacturing of asbestos reinforced plastics. OSHA'a data are presented as "means" which are assumed to be arithmetic means. The
values corresponding to the total populations are calculated as weighted averages based on the number of workers exposed in each Job category. The exposure
value for secondary manufacturing is determined from monitoring data.
The duration of exposure is assumed to be 8 hours/day In all cases.
frequency refers to the number of days annually that the workers are performing a task involving potential exposure to asbestos. The frequency Is assumed to
be 250 days/year for all Job categories.
Sources: NIOSH 1983a, 1984f; OSHA 1986b; ICF Market Survey 1986-1987.
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filling of -- allon drums with asbestos-reinforced plastic pellets (NIOSH
1983a). This cask is performed only about once per week.
In the second NIOSH study, one personal and four area samples were
collected for airborne asbestos; this personal sample indicated an exposure of
1.2 f/cc for the grinder operator (NIOSH 1984f).
Asbestos-reinforced plastics have a relatively small asbestos content
compared to the other ingredients involved in resin forming. Manual bag
opening methods have normally been used to handle this quantity of dry
asbestos. Central ventilating systems with exhaust hoods are the prevalent
controls used in the bag opening area. Some large manufacturers use limited
enclosure of their areas for better control of exhaust air flow.
Control equipment utilized at the dry blending step includes exhaust
hoods, local process exhaust equipment, and partial enclosures to control air
flow and minimize asbestos dust exposure in surrounding areas. Housekeeping
and maintenance practices are identical to those used in fiber introduction
areas; they range from manual floor and equipment sweeping to central
vacuum-cleaning systems and mobile sweeper/vacuum machines.
Engineering controls at the mixing and forming stages generally include
exhaust hoods and partial enclosure of process equipment. Housekeeping and
maintenance practices are similar to those employed in the earlier processes.
Curing usually requires an enclosed area furnished with a ventilating system.
When air curing is involved in this process, hoods and local enclosures should
be provided.
Following the curing process, the product is finished. This could involve
sawing, drilling, machining, and grinding, depending on the end use of the
product. Asbestos dust is released when the plastic products undergo these
finishing processes. Hand and portable tools are normally supplied with local
exhaust systems connected to the central ventilation/collection system. LEV
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is employed near the finishing surface of large, stationary machines; and, a
times, hoods are installed over the finishing machines as a supplementary
control. Where large amounts of dust are released, area or machine partial
enclosures can be used. Housekeeping practices are very important at these
final processing stages and are similar to those employed in previous dry
processing steps.
Based on the exposure data presented in Table 19 and technologies
currently available in other primary sectors, projected asbestos exposure
levels are expected to be below the current PEL of 0.2 f/cc. Wider use of
respirators is anticipated for dry-mechanical processes and the high
exposures, shown in Table 19, should be greatly reduced. The 8-hour TWA
exposure exhibited for secondary fabricating in Table 19 further indicatp-
feasibility of achieving low levels in this sector. The projected
value for secondary fabricating is substantially lower than the
PEL value due to the expected reduction via the technologies discussed abo,.
9. Miscellaneous Products
a. Production Data
There is some information available regarding the status of
companies manufacturing miscellaneous asbestos products. Asbestos production
data derived from the ICF Market Survey (1986-1987) indicate that three
asbestos products not previously categorized are manufactured in the U.S.
These products have been identified as acetylene cylinders, battery
separators, and arc chutes. Although production data does exist for these
products, no occupational exposure data has been located; nevertheless, it is
important to acknowledge the existence of these uncategorized, y ...~.iy
produced asbestos products which result in potential occupational exp. •> to
asbestos.
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The primar manufacture of these three products consumed 493.6 short tons
of asbestos in 1985 and potentially exposed 371 asbestos workers (ICF Market
Survey 1986-1987).
Table 20 summarizes the production data for each one of these products.
There are no known secondary manufacturers or importers of these products.
b. Product Descriptions
(1) Filler for Acetylene Cylinders
Asbestos is used to produce a sponge-like filler that is placed
in acetylene cylinders. The filler holds the liquefied acetylene gas
(acetone) in suspension in the steel cylinder and pulls the acetone up through
the tank as the gas is released through the oxyacetylene torch. The torch is
used to weld or cut metal and is sometimes used as an illuminant gas. The
filler also acts as an insulator that offers fire protection in case the
oxidation of the acetylene becomes uncontrollable. The desirable properties
of asbestos in this function include its porosity, heat resistance,
anti-corrosiveness and its strength as a binding agent (ICF Market Survey
1986-1987).
(2) Battery Separators
In very specialized aerospace applications, asbestos functions
as an insulator and separator between the negative and positive terminals of a
fuel cell/battery. The porous nature of the 100 percent woven-asbestos
material allows it to absorb the liquids used in fuel cells and batteries.
The liquids used in these fuel cells/batteries are highly corrosive and reach
high temperatures in this application. The properties of asbestos that are
desirable in this function are its porosity, heat resistance, anti-
corrosiveness, strength and dielectric strength (ICF Market Survey 1986-1987).
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Table 20. Production Data for Miscellaneous Products
Production Volume
Asbestos
Fiber
Consumed
(short tons)
Number
.of Workers
Potentially
Exposed
to Asbestos
Acetylene Cylinders 308,121 pieces
Battery Separators 2,046 Ibs
Arc Chutesa 900 pieces
479.1
1.0
13.5
162
207
2
processors of asbestos arc chutes manufacture plastic arc
chutes that have been classified in the asbestos-reinforced plastics
category. Generally, the plastic arc chutes are smaller and are not
able to withstand as high a temperature (above 1500°F) as the
ceramic arc chutes. The plastic arc chutes are used in smaller
electric motors, often in the automotive and appliance industries
(ICF Market Survey 1986-1987).
Source: ICF Market Survey 1986-1987.
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(3) Arc Chutes
Ceramic arc chutes containing asbestos are used to guide the
electric arc in motor starter units in electric generating plants. The
asbestos is used in the arc chutes for its strength, heat resistance, and
dielectric strength.
C. Chlorine Manufacture (Asbestos Diaphragyn Cells)
1. Process Description
Asbestos diaphragm cells represent one type of electrolytic cell
employed in the chlor-alkali industry for the production of chlorine and other
primary products such as caustic soda. There are presently three types of
electrolytic cells in commercial use: asbestos diaphragm cells, mercury
cells, and membrane cells. As of mid-1985, 77 percent of the U.S. industry's
total installed chlorine production capacity was in electrolytic cells
equipped with asbestos diaphragms (Chlorine Institute 1986a). Mercury cell
technology accounted for about 17 percent of the capacity, while membrane cell
technology, recently developed, accounted for 2 to 3 percent (Chlorine
Institute 1986a).
All electrolytic cells operate on the same principle in the production of
chlorine by brine electrolysis. An electric current decomposes a solution of
brine into chlorine, caustic soda, and hydrogen; the former is liberated at
the anode and the latter two at the cathode. The ratio of chlorine to caustic
soda produced during the process is 1 to 1.1 by weight (Chemical Week 1982).
During this process, it is necessary to keep the chlorine gas separated from
the alkali metal hydroxide co-product to prevent chemical reaction.
Separation is achieved by use of an asbestos diaphragm which basically acts as
a mechanical barrier between the two chambers.
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The proper operation of the diaphragm cell depends greatly on the
diaphragm material. The diaphragm requires some of the following properties
in order to function properly (Chlorine Institute 1986a):
• Sufficient mechanical strength;
• High chemical resistance to acids and alkalies;
• Favorable electrical energy efficiency;
• A physical structure that permits percolation of depleted
brine with minimum back-migration; and
• Feasible service life.
Asbestos exhibits an extremely favorable comb ation of these properties
making it uniquely well suited as a diaphragm acerial.
In the application of asbestos in the diaphragm forming process, a layer
of asbestos slurry is drawn by vacuum techniques through a screen or
perforated plate. Asbestos fibers are deposited on the screen, or plate,
forming a paper-like mat approximately an eighth of an inch thick (Coats
1983). The resulting asbestos-coated screen is the diaphragm and is used as
the cathode in the electrolytic cell. Asbestos diaphragms ar
at the chlorine plant site itself; they are not available as pi
products ready for use.
Research has established that the deposited asbestos fibers do not only
function as filter-type mats. Under proper cell diaphragm depositing and
operating conditions, a gel layer forms in the mat. This gel layer greatly
aids in the diaphragm performance by optimizing power-efficiency. Over the
past twenty years, many advances have been made in the design 3
diaphragms and in the design of the cell itself. These have inciuued -r.s
introduction of novel types of anodes and the development of modified asbestos
diaphragms. These resin bound diaphragms consist of chrysotile and polymeric
powders of fibers stabilized at high temperatures before use. This
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development increases the stability of asbestos diaphragms and extends their
service life. These and other innovations have resulted in a significant
reduction in asbestos consumption per ton of chlorine over the years (Chlorine
Institute 1986a). The majority of diaphragm cells currently in use in the
U.S. utilize these modified asbestos diaphragms; they consume 2,300 kwh of
power per ton of chlorine produced (Chlorine Institute 1986a, Chemical Week
1982).
The surface of the diaphragm ranges from approximately 200 to 1000 square
feet for a cell with a volume of 64 to 275 cubic feet (Coats 1983). Each
diaphragm may use up to 200 pounds of asbestos and have a service life of
three months to over one year, depending on the type of anode in use (Chlorine
Institute 1986b). Using modified asbestos diaphragm technology, the
production of 1000 tons of chlorine as well as other primary products requires
about 250 pounds of asbestos (Chlorine Institute 1986b).
Due to impurities in the brine solution and a variety of operating
conditions during cell operation, the asbestos diaphragm requires periodic
replacement. When replacement is required, the cell is shut down, dismantled,
and the asbestos diaphragm is removed, thus maintaining the desired level of
chlorine processing efficiency. The spent asbestos diaphragm is physically
separated from the cathode frame. This procedure occurs in a designated plant
area while the diaphragm is still wet. The liquid waste containing asbestos
is settled, decanted or filtered, and the separated solids are subsequently
disposed.
2. Manufacturers Using Asbestos Diaphragms
Asbestos diaphragms are not marketed; the chlorine producers purchase
asbestos fiber and manufacture and install the diaphragm themselves. Table 21
provides a list of chlorine manufacturers who use asbestos diaphragm cells.
In 1985, 19 manufacturers were operating 30 chlorine plants using asbestos
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Table 21. Producers of Chlorine Using Asbestos Diaphragms*
Plant
Annual Capacit
(Thousands off
Metric Tons)
Brunswick Pulp & Paper Company
Brunswick Chemical Company, Division
Diamond Shamrock Corporation6
Diamond Shamrock Chemicals Company
Chlor-Alkali Division
Dow Chemical U.S.A.
E.I. duPont de Nemours & Co., Inc.
Petrochemicals Department
Freon Products Division
FMC Corp., Industrial Chemical Group
Formosa Plastics Corporation, U.S.A.
Fort Howard Paper Company
General Electric Company
Plastics Business Operations
Georgia-Gulf Corporation
The B.F. Goodrich Company6
Convent Chemical Corporation,
Subsidiary
Kaiser Aluminum and Chemical Corp.
Kaiser Industrial Chemicals Division
LCP Chemicals and Plastics, Inc.
LCP Chemicals Divisions
Occidental Petroleum Corporation
Occidental Chemical Corporation,
Subsidiary
Hooker Industrial and Specialty
Chemicals
(Location not known)
Deer Park, TX
La Porte, TX
Oyster Creek, TX
Pittsburg, CA
Plaquemine, LA
Freeport, TX
Corpus Christi, TX
Charlotte, NC
Baton Rouge, LA
Green Bay, VI
Mount Vernon, IN
Plaquemine, LA
Convent, LA
Gramercy, LA
Solvay, NY
Montague, MI
Niagara Falls, NY
Taft, LA
Tacoma, VA
27
3601
465
320
180
1,050
2,330
297
263
180
410
261
181
831
76
279
636
181
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Table 21 (Continued)
Plant
Annual Capacity
(Thousands of
Metric Tons)
Olin Corporation
Olins Chemicals Group
Pennwalt Corporation
Chemicals Crop
Inorganic Chemicals Division
PPG Industries
Stauffer Chemical Company
Chlor-Alkali Products Division
Vulcan Materials Company
Vulcan Chemicals, Division
Weyerhaeuser
Mclntosh, AL
Federal Way, WA
Portland, OR
Wyandotte, MI
Lake Charles, LA
New Martinsville, WV
Henderson, NV
Geismar, LA
Wichita, KS
346
82
136
91
l,041b
255b
Longview, WA
TOTAL
104
220
237C
136
9,295d
aAs of January 1, 1985.
^Combined capacity for asbestos diaphragm cell and mercury cell.
cCombined capacity for asbestos diaphragm cell and membrane cell.
^Total assuming that half the capacity at facilities using asbestos diaphragm
cells and some other kind of cell is attributed to the asbestos cell.
Accidental Chemical bought all chlorine plants from Diamond Shamrock and The
B.F. Goodrich Company (ICF Exposure Survey 1986-1987).
Sources: SRI 1985, Chemical Business 1985, Chemical Engineering 1976,
Vulcan Chemicals 1986, Chemical Week 1986, ICF Exposure Survey
1986-1987. (ICF's best estimates based on these sources).
- 113 -
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diaphragm cells with an estimated total annual capacity of approximately 9.3
million metric tons (10.2 million short tons). The largest of these chlorint
producers was Dow Chemical, with a combined annual capacity of 3.9 million
metric tons (4.3 million short tons), approximately 42 percent of the total
asbestos diaphragm cell chlor-alkali capacity, followed by Occidental
Chemical, accounting for about 13 percent of the asbestos diaphragm cell
chlorine production capacity. Asbestos diaphragm cell chlorine production
accounts for about 77 percent of the total chlorine production (see Table 22.
Chlorine production and asbestos fiber consumption information for the
period 1983-1985 is presented in Table 22. Based on this infonaation, about
975 tons (i.e., short tons) of asbestos was consumed by the chlorine industrj
in the production of approximately 10 million tons of chlorine in 1985.
Based on worker population data provided by the respondents of
Exposure Survey (1986-1987), approximately 0.07 workers are exp-
asbestos for every metric ton of asbestos diaphragm cell capacity. Therefore
an estimated 650 workers are exposed to asbestos during chlorine manufacture.
(The Chlorine Institute (1986a) estimated that about 225 workers are involved
in asbestos handling operations.)
3. Exposure Profile
The results for 8-hour TWA exposure to asbestos during the manufacture
of chlorine are presented in Table 23 for several job categories. These
values are based on the raw monitoring data. As revealed by the data and the
geometric and arithmetic mean values in Table 23, there is minimal
occupational exposure for chlor-alkali workers to asbestos fibr .
Apparently, exhaustive and continuous efforts are made by the industry to
minimize the number, frequency, and duration of worker exposure to asbestos.
The Chlorine Institute, Inc. (1986a) states that workers in this industry
are assigned to periodic, short-term tasks involving the handling of asbestos
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Table 22. Chlorine Production/Asbestos Fiber Consumption
1
rear
1983
1984
1985
2
Total
Chlorine Capacity
(millions of ton»)b
14.6
13.6
13.2
3
Capacity
Utilization
Rata
(on Average)
661
721
77X
I
Production of
Chlorine
(millions of tons)b
(2 x 3)
9.64
9.79
10.16
5
Percentage of
Production
Using Asbestos
Diaphragms
77. Oc
77. Oc
76.7'
6
Quantity
of Chlorine
Produced Using
Asbestos Diaphragms
(millions of tons)
(4 x 5)
7.42
7.54
7.80
7
Ratio of
Asbestos
Fiber
Consumption
to Chlorine
Production*
0.000125
0.000125
0.000125
8
Consunption of
Asbestos Fiber
(tons)
(6 x 7)
928
943
975
"Chlorine Institute 19B6b.
bChamlcal Week 1985.
cCoats 1963.
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Table 23. Exposure Profile for Asbestos Diaphragm Cells
... ... 8-Hour TWA Exoosure (f/cc)
Product Job Category"
Asbestos Diaphragm Cells Brine/Sludge Worker
Cell Worker
Yard Worker
Other
Total
Population
165
410
38
_2Z
650
Pre-0.2
Geometric Mean
0.009 (8)
0.024 (252)
0.007 (6)
0.019 (18)
0.019
f/cc PELC
Arithmetic Mean
0.010
0.083
0.012
0.033
0.058
Post-0.2
Geometric Mean
0.009
0.022
0.007
0.019
0.018
f/cc PEL"
Arithmetic Mean
0.010
0.052
0.012
0.033
0.038
Duration
(hr/day)d
8
8
8
8
Frequency
(days/year)*
250
250
4
6
220
aJob categories are based on a concise categorization of the job titles.
bThe total population is estimated based on information provided'in the ICP Exposure Survey (1986-1987) and the asbestos diaphragm cell chlorine capacity.
The distribution of the total number of workers exposed into specified Job categories ia based on the raw data. The total population is allocated into Job
categories by selecting one of each type of Job (i.e., Job titles, as shown in monitoring data) for each Job category, and then totalling the individual Job
title populations which are either provided in the specific study or estimated. The populations Include workers from all shifts.
cThese values represent geometric and arithmetic means of the raw 8-hour TWA exposure data. The number of data points is given in parentheses. The value
corresponding to the total population la calculated as a weighted average based on the number of workers exposed in each Job category.
d
These post-0.2 f/cc PEL exposure value* are calculated directly from the monitoring data. Each 8-hour TWA exposure value that is above 0.2 f/cc is reduced
to exactly 0.2 f/cc. Data that art already at or below this value remain unchanged. The valua corresponding to the total population la determined in the
same manner as the pre-0.2 f/cc PEL total exposure value.
"The duration of exposure is 8 hours/day in all cases. Where no duration is provided, 8 hours/day is assumed. Exposures for less than 8 hours are converted
to 8-hour TWAs, assuming zero-exposure during periods when the worker is not handling asbestos.
Frequency refers to the number of days annually that the workers are performing a task involving potential exposure to asbestos. The frequency is not
assumed to be 250 days/year for all Job categories alnea data for specific Job types indicate otherwise. For the "yard worker" and "other" categories,
information shows that the performance of these Jobs (yard work and maintenance pipe fitting) is very infrequent.
Sources: ICF Exposure Survey 1986-1987, ICF Market Survey 1986-1987, HIOSH 1983b, Chlorine Institute 1986a.
-------
fibers. Thes- workers are trained, equipped with respirators and/or work in a
non-exposure ervironment. Asbestos diaphragms are wet for most of the time
they exist;' the cell in which they are contained is a fully enclosed system,
essentially precluding the release of airborne fibers (Chlorine Institute
1986a). All "spent" diaphragms are subject to controlled disposal at the end
of their useful lives.
The principal potential sources for exposure to asbestos among ohlor-
alkali workers are associated with receiving, storage, weighing, diaphragm
depositing, diaphragm rebuilding, and disposal (Chlorine Institute 1986a).
Thus, the cell worker receives the highest exposure, as shown in Table 23.
The weighing of asbestos in the dry state is the work activity with the
highest exposure potential (Chlorine Institute 1986a). Dry handling
operations take place in dedicated plant areas with restricted access and
respiratory protection. Weighing occurs in equipment engineered to control
asbestos emissions.
Whenever feasible, dry asbestos is wetted at the earliest opportunity, and
subsequently used as a liquid slurry. The process of removing asbestos from a
diaphragm cell is conducted under wet conditions to avoid the possibility that
inner layers of dry asbestos exist.
Strict housekeeping and monitoring practices are required by the industry.
Accidental spills of asbestos are cleaned up immediately, either by vacuum or
wet sweeping. Wash down systems are employed; all equipment used in asbestos
handling is washed down in a trench system. Complete individual exposure
evaluations are periodically conducted for all personnel potentially exposed
to asbestos dust.
Hence, exposure levels are low for all .job categories. Except for a few
cell workers, all monitoring data are below the 0.2 f/cc level. Thus,
- 117 -
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projected exposures are identical to pre-0.2 f/cc PEL posures for all cases
except in the cell worker category where a slight decrease is expected.
4. Frequency and Duration of Exposure
As indicated by the monitoring data, most operations require less th<
a full day of work and typically occur about 250 days per year. The duratioi
presented in Table 23, however, are all 8 hours per day because the exposure
levels are converted to 8-hour TWAs. The various sources provided the data
8-hour TWA levels. Thus, the duration is taken as 8 hours per day, not the
actual duration of exposure, because the short exposure duration is already
accounted for in the exposure level (Donahue 1987).
Nevertheless, several jobs are carried out quite infrequently. Data
suggests that the yard worker is exposed only 4 days per year (ICF Ex-
Survey 1986-1987). Exposure durations associated with the task cr
asbestos in the dry state range from 10 to 120 minutes (averaging 30 to 60
minutes) and occur from one to seven times weekly.
D. Brake Repair Service
Asbestos is currently used in drum brake linings for the rear brakes of
most automobiles. Most new cars have drum brakes, and most new drum brake
linings contain asbestos while a small percentage are non-asbestos; nearly al-
older cars have asbestos drum brake linings in the rear brakes. The nv> -;-
of disc brake pads, used in the front brakes of most automobiles an
rear brakes of a small number of automobiles, are non-asbestos for newer ca_
however, a sizeable percentage of disc brake pads on older cars still contain
asbestos. A majority of heavy vehicles have asbestos brake linings. Thus,
most automobiles and trucks have asbestos brake linings that requ periodic
servicing (i.e., inspection, adjustment, or replacement). In additi. me
automobiles have asbestos clutch facings or automatic transmission components
which must be replaced periodically. Industrial equipment may also contain
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asbestos fricL-on materials such as brake linings of various types, clutch
facings, and transmission components that require periodic servicing.
Exposure data on the repair of friction products are available only for
automotive brakes; no data have been found for other friction products such as
industrial brakes and clutches. Therefore, this section focuses on exposures
during automotive brake servicing; automotive brakes are the largest segment
of the friction products category, consuming about 91 percent of the asbestos
used in this category (based on IGF Market Survey (1986-1987) estimates).
Repair of other types of brakes may lead to exposures similar to those found
for automotive brakes. However, exposures from repair of paper-type friction
materials such as automatic transmission components and industrial wet
friction components, where wear debris from friction is trapped in a fluid,
are likely to be much lower than for automotive brakes.
1. Exposure Setting/Process Description
Automobiles, trucks, and other vehicles with asbestos-containing brake
lining materials require periodic brake servicing and replacement of the brake
linings. Brake servicing may be carried out in specialized brake service
facilities, full-service garages, service stations, dealer shops, or
self-serviced fleet shops (Hunter Publishing Co. 1985). Brake servicing
includes removal of the wheels and drums (in the case of drum brakes),
cleaning of the brake assembly and drum, and replacement of the worn linings,
if necessary. Worn linings are usually removed still attached to the shoe or
plate and new linings, already attached to shoes, are used for replacement;
mechanics rarely attach new linings to shoes during brake servicing. There is
usually no grinding or drilling of brake linings for automobiles or trucks
during servicing (ATA 1985, Sears 1985).
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Rebuilding of brakes, by stripping off the old , : ing material and
replacing it with a new lining, is considered a secondary manufacturing
procedure and is discussed in Section B of this chapter.
Brake cleaning procedures vary. In the past, it was common practice to
blow out dirt and debris from the brakes and drums using compressed air; th:
method of cleaning has been prohibited by OSHA in a rule which went into
effect on July 26, 1986 (OSHA 1986a). Other common cleaning methods include
the use of liquid brake cleaners, wiping the parts and drums with a wet rag,
use of a wet or dry brush, and various combinations of methods. Enclosed
vacuum systems are also available for brake cleaning. Some facilities may
require the use of dust masks by brake repair workers (Sears 1985), but this
practice appears to be unusual. Host brake repair workers do not use dust
masks or respirators (ATA 1985, Precision Import Service 1985). B~
cleaning and asbestos control procedures and devices are desc
a. Compressed Air/Solvent Mist
Brake cleaners, which contain solvents such as 1,1,1-trichloro-
ethane (PEI 1985), may be incorporated into the compressed air system and
sprayed on the brake assembly. OSHA allows this method of cleaning,
presumably because the solvent mist captures the dust and asbestos fibers.*
PEI Associates (1985) points out, in a study of control methods, that it is
important that the solvent be collected for recycle. If the solvent is
allowed to evaporate, the asbestos may be reentrained in the air. It is not
»
known to what extent the solvent is recycled when this method is used.
OSHA presents the compressed air/solvent system method as a preferred
method for brake repair even though use of compressed air is prohibited unles*
an enclosed ventilation system is used (OSHA 1986a, pp. 22753, 22758).
- 120 -
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b. Hrush
Dust and debris may be removed from brake assemblies by use of a
brush. According to PEI Associates (1985), this method may cause dust to fall
on the worker's clothing and in the immediate area. The amount of exposure
may be highly dependent on the worker's work practices.
A variation of this method is use of a brush that is wet with water or
another liquid to keep the dust down.
c. Water Sprav/Rag
Water may be applied to the brake assembly by squirt bottle or
hose, and the brake parts then cleaned with a rag. This method, like brush
cleaning, may cause contamination of clothing and accumulation of dust on the
garage floor. Exposure may be highly variable, depending on individual work
practices (PEI Associates 1985).
d. Brake Washer
NIOSH (1987a) describes a brake washer assembly unit used to
control asbestos; other designs are commercially available. The unit
described by NIOSH contains a water solution that is pumped through a flexible
tube with a brush attached to clean the brake parts. A removable upper tray
holds small parts and catches the solution; the bottom tank is used for
cleaning brakes on larger vehicles. The solution is filtered and
recirculated.
Some brake washer units are connected to a compressed air gun. Liquid is
siphoned into the air line and sprayed onto the brake parts for cleaning. The
liquid runs off the parts into a perforated pan which catches debris; the
liquid that drains through is recycled (PEI Associates 1987).
PEI Associates (1985) reports finding garages that do not use their brake
washers as intended, using them as parts washers instead.
- 121 -
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e. Vacuum Unit Without Enclosure
A vacuum unit with a High Efficiency Parti-ulate Air (HEPA) filte
for use in brake servicing is described by NIOSH (1987b). The unit consists
of a dust removal hose, used to suck loose dirt from the brake assembly
surface, connected to a three-stage vacuum dust filter assembly. This unit
originally included an enclosure, which was removed by the user. According
PEI Associates (1987), no HEPA vacuum units without enclosures are'currently
being marketed for collection of asbestos from brake maintenance; however,
units marketed for other purposes might be used for brake cleaning, and unit;
sold with enclosures might be-used without the enclosures, as described in tl
NIOSH study.
f. Vacuum Unit with Enclosure
HEPA vacuum units with enclosures are commercially available.
These units typically have enclosures that surround the brake drum, and have
glove inserts for the worker's hands. Compressed air is used inside the
enclosure to clean the brake parts, and the dust is removed by vacuum. A
number of different models of this type of system are commerci
NIOSH (1987c) studied a facility where mechanics performed brake t>c.
using a vacuum enclosure unit, consisting of a glove box enclosing the brake
assembly and a hose connection to a three-stage vacuum dust filter assembly.
Using the glove box, mechanics can perform brake cleaning and other operations
within the enclosure with a compressed air gun, a vacuum line with brush
attachment, a hammer or mallet, and a separate brush.
NIOSH (1987b) reports that one company stopped using enclosures with its
vacuum units because mechanics complained of dust escaping during use. PEI
Associates (1985) mentions contamination due to buildup of asbestos inside the
enclosure and mechanics finding the system cumbersome as additional problems
with vacuum enclosure systems.
- 122 -
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2. Current Exposures
Monitoring data for a number of brake servicing facilities, both for
the period of brake servicing and expressed as 8-hour TWAs for brake
mechanics,* are presented in Table 24. The 8-hour TWA data are included for
comparison with the.OSHA PEL. The data are grouped according to whether the
brake cleaning methods used are non-engineering or engineering controls, and
are presented by type of cleaning method or control used. It should be noted
that the data by control type are limited. For several of the controls, data
are available from only one facility; and only a few data points are available
for other controls. Details of work practices followed when using the non-
engineering controls are not available, and only a few models of the available
types of devices are represented by the engineering control monitoring data.
Because exposures may vary by type of vehicle (i.e., automobile versus truck),
type of brake (i.e., drum brake versus disc brake), type of facility,
individual work practices, and control device used, and because background
asbestos levels are not available, the data in Table 24 cannot be used to make
accurate comparisons of the effectiveness of the various control methods.
The data presented in Table 24 are personal sampling results from NIOSH
studies. Similar methods of sample collection and analysis were used in all
the studies. The samples were analyzed by phase contrast microscopy, using a
For short-term, non-manufacturing jobs such as brake repair, the
reported exposure levels are short-term TWAs (Reed 1987). To calculate the
8-hour TWA exposure from the TWA exposure for the period of time sampled, the
following equation is used:
Sampling Time (minutes)
8-Hour TWA - x TWA for Period of Time Sampled
480 Minutes
One asbestos brake job per 8-hour period is assumed in this calculation,
although the number of brake jobs may vary widely by facility. The sampling
time serves as a surrogate for the time of job performance.
- 123 -
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Table 24. Asbestos Exposure Daring Brake Servicing, By Control Method
Vehicle
Control and/or Brake Type
Non-EnftinaerinR Controls
Compressed Air/ MA
Solvent Mist
Compressed Air/ Front disc brakes
Solvent Mist 4 -Wheel disc brakes
Front disc brakes
Front disc brakes
and rear shoes
Front disc brakes
and rear shoes
Dry Brush NA
Brush Wet with NA
Gasoline
Hater Squirt NA
Bottle and Rag
TWA for
Time Sampled
(f/cc)
0.08
0.07
0.060
0.030
0.070
0.002
0.010
0.20
0.21
0.34
0.08
0.03
0.15
0.44
0.15
0.30
0.31
0.26
0.24
0.33
0.12
Sampling Time
(minutes)
343
283
77
239
54
162
210
129
68
124
177
47
162
184
ISO
196
175
194
135
136
190
8-Hour TWA*
-------
Table 24 (Continued)
NJ
Ln
Control
Vehicle
and/or Brake Type
TWA for
Time Sampled
(f/cc)
Sampling Time
(minutes)
8-Hour TWA8
(f/cc) Source Notes
Engineering ControU
Brake Hasher
Assembly Unit
HEPA Vacuum
Unit Without
Enclosure
Jeeps
Passenger Car
Passenger Car
Van (1/2 ton)
Van (1/2 ton)
Passenger Car
Van (1/2 ton)
Van (1/2 ton)
Van (1/2 ton)
Van (1/2 ton)
Van (1/2 ton)
Van (1/2 ton)
Van (1/2 ton)
Van (1/2 ton)
0.0041
0.0042
0.0041
0.0042
0.0042
0.0041
0.0041
0.0041
0.0041
0.0042
0.0042
0.0041
0.0041
0.0042
0.0036
0.0043
0.0040
0.0040
0.0042
0.0041
0.0133
0.0078
0.0163
0.0033
0.0042
0.0040
0.0040
0.0034
0.0055
0.0070
0.0092
0.0040
0.0039
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
0.001° HIOSH 1987a Post Office motor vehicle maintenance
0.001° facility; source reports only one sample
0.001° a-bove the detection limit of 0.004 f/cc.
0.001C
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.004C HIOSH 1987b Fleet maintenance facility.
0.002°
0.00*c
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.002°
0.002°
0.001°
0.001°
-------
Table 24 (Continued)
Control
Vehicle
and/or Brake Type
TWA for
Time Sampled
(f/cc)
Sampling Time
(minutes)
6-Hour THA*
(f/cc)
Source
Notes
Engineering Control* (Continued)
NJ
HEPA Vacuum
Unit with
Enclosure
BEPA Vacuum Unit
with Enclosure
Van
Van
Truck (1/2 ton)
Truck (1/2 ton)
Truck (1/2 ton)
Truck U/2 ton)
Automobile
Automobile
Truck (1/2 ton)
Truck (1/2 ton)
Salt Truck
Salt Truck
Automobile
Automobile
Truck (1/2 ton)
Truck (1/2 ton)
Truck (1/2 ton)
Truck (1/2 ton)
HA
0.0041
0.0041
0.0042
0.0042
0.0041
0.0041
0.0038
0.0038
0.0042
0.0042
0.0036
0.0036
0.0042
0.0042
0.0029
0.0029
0.0033
0.0033
0.01
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
240
0.001° HIOSH 1987o Department of Transportation maintenance
0.001° facility; source reports no samples above
0.001° the detection limit of 0.004 f/cc.
0.001C
0.001C
0.001C
0.00lc
0.001C
0.001C
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.001°
0.005 NIOSH 1982b Private fleet service garage.
Hotel: Airborne fibers may be 30 percent (NIOSB 1982b) to 55 percent (NIOSH 1980c) chryaotile asbestos. The remaining fibers may be up to 20 percent
foratarits, probably produced from chryaotile by the high temperatures of braking (HIOSH 1982b) and up to 50 percent unknown. Some of the
unknown fibers are probably intermediate between chrysotile and forsterlte (NIOSH 19B2b). Samples were analyzed by phase contrast microscopy.
Results presented are for single samples.
* 8-hour THA was calculated from the THA for the time of the brake job aa follows:
8-hour THA - Semolina Time (minutes) x THA for Period of Time Sampled
480 Minutes
One brake job per 8-hour period is assumed in this calculation. The sampling time serves aa a surrogate for the time of job performance.
Sampling time was 2 hours or duration of brake job, whichever was longer. Exect time was not given.
c Sampling time assumed to be 2 hours.
-------
procedure that requires counting of fibers greater than 5 urn in length and
with at least a 3 to 1 length to width aspect ratio.
While exposures vary by facility and by cleaning method, the TWAs for the
time sampled and the 8-hour TWA exposures are generally less than 0.2 f/cc.
Exposure levels measured during use of the brake washer assembly unit and the
HEPA vacuum enclosure were nearly all at or below the detectable limit of
0.004 f/cc; the vacuum unit without enclosure also produced similar exposure
levels. The brake washing device in use during NIOSH's study used water
pumped through a brush. Exposure data for a brake washer that uses compressed
air are not available; it is possible that exposure levels might be quite
different with this type of device. It is also possible that different
results might be obtained with other models of the vacuum enclosure system.
The data presented represent few specific sites. Host of the exposure data
reported for the engineering controls are from large government fleet
maintenance facilities which may not be representative of the average
workplace because workers are paid by the hour and are, therefore, not under
time constraints to perform their work quickly. In addition, potential
exposures during parts washer or vacuum unit servicing and clean-out have not
been addressed.
Data from Table 24 are summarized, and the geometric and arithmetic means,
for both the time sampled and the 8-hour TWA, are presented by control type in
Table 25. Because the data are very limited, both in the number of data
points available and the number and types of facilities monitored, it is not
possible to draw definite conclusions about the relative effectiveness of the
controls presented. The range of asbestos concentrations reported for some of
the controls varies widely, and the ranges reported for various control types
overlap.
- 127 -
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Table 25. Sunmary of Asbestos Exposure by Control Method, With Calculated Means
Reported TWA Exposures
Number of
Cleaning Method Facilities
Compressed Air/Solvent Mist 2
Dry Brush 1
Wet Brush 1
Water Squirt Bottle/Rag 1
fo All Non-Engineering Controls 5
oo
i
Engineering Controls
Brake Washer Assembly Unit 1
HEPA Vacuum Unit Without 1
Range of
Nunber Sample Times
of Samples (minutes)
7 54-3*3
7 47-184
5 135-196
2 136-190
21 47-343
20 a
13 a
Range
of Values
(f/cc)
0.002-0.06
0.03-0.44
0.15-0.31
0.12-0.33
0.002-0.44
0.0040-0.0056
0.0040-0.0163
Geometric
Mean
(f/cc)
0.028
0.16
0.24
0.20
0.10
0.004
0.006
Arithmetic
Mean
(f/co)
0.046
0.21
0.25
0.22
0.17
0.004
0.007
Calculated
Range
of Values
(f/cc)
0.001-0.057
0.003-0.169
0.047-0.122
0.0*8-0.09*
0.001-0.169
0.001*
0.001-0.004*
8-Hour TWA
Geometric
Mean
' (f/cc)
0.010
0.038
0.086
0.067
0.031
0.001
0.002
Exposures
Arithmetic
Mean
(f/cc)
0.019
0.061
0.091
0.071
O.OSS
0.001
0.002
Enclosure
HEPA Vacuum Unit With
Enclosure
All Engineering Controls
All Cleaning Method* and
Controls
19
52
73
120-240 0.0029-0.01 0.004 0.004 0.001-0.005 0.001 0.001
120-240 0.0029-0.0163 0.004b 0.00*b 0.001-0.005
*7-343 0.002-0.44
0.09
0.15 0.001-0.169
0.001 0.001
0.028b 0.050b
Sample time was 2 hours or period of brake Job, Whichever was longer; 2 hours assumed for 8-hour TWA calculation.
Weighted according to estimates of use by PEI Associates (1967) (see text).
Source: See Table 24.
-------
No data are available on frequency of use of various non-engineering
cleaning methods, such as brush, rag, and solvent mist. Combining the
exposure data for the various non-engineering cleaning methods, giving equal
weight to each data point, the geometric mean TWA exposure for the time of
brake servicing with no use of engineering controls is 0.10 f/cc. The
arithmetic mean TWA exposure for the time of brake servicing with no use of
engineering controls is 0.17 f/cc.
PEI Associates (1987) has estimated use of engineering controls as
follows:
• Brake washer --6 percent of facilities (63 percent of
facilities using engineering controls);
• HEPA vacuum unit without enclosure -- less than 1 percent
of facilities (less than 10 percent of facilities using
engineering controls); and
• HEPA vacuum unit with enclosure -- 2.6 percent of
facilities (27 percent of facilities using engineering
controls).
If the geometric mean exposure level reported for each of the engineering
control methods is weighted by the percent of all facilities using engineering
controls that use each individual control, the geometric mean TWA exposure for
the time of brake servicing using engineering controls is 0.004 f/cc. The
weighted arithmetic mean TWA exposure for the time of brake servicing using
engineering controls is also 0.004 f/cc.
An overall geometric mean TWA exposure for the time of brake servicing was
estimated using the PEI (1987) estimates presented above for use of each type
of control. It was assumed that the exposure level for all facilities that do
not use engineering controls (90.4 percent of the total) is represented by the
geometric mean calculated for non-engineering controls (0.10 f/cc); this
exposure level was weighted by 90.4 percent. The geometric mean exposures for
each of the engineering controls were weighted by the PEI estimates of current
- 129 -
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use. The overall weighted geometric mean TWA exposure for the time of brake
servicing was calculated as 0.09 f/cc. The overall weighted arithmetic mean
TWA exposure for the time of brake servicing, calculated by similar methods,
is 0.15 f/cc.
We have not attempted to determine exposure for repair of each type of
automotive brake lining because of insufficient data. It is likely that
airborne asbestos dust concentrations may be lower during disc brake pad
replacement than drum brake lining replacement because for disc brakes much o
the wear debris is released to the air during use; there is no drum to collec
brake dust and debris as there is for drum brakes. However, there are no dat<
to verify differences in exposure levels; therefore, we have assumed that the
average exposure is applicable to all types of brakes.
3. Populations Exposed
The Hunter Publishing Company (1985) lists four types of service
facilities that may perform brake work:
• Service stations;
• Independent repair shops;
• New car and truck dealer shops; and
• Self-serviced fleet shops.
Table 26 shows 1984 estimates provided by Hunter Publishing, based on survey
data, of the number of facilities of each type, the average number of
full-time employees per facility, the average number of full-time mechanics
per facility, and the total number of full-time mechanics.*
The Hunter Publishing estimates of total facilities and employees do not
include facilities such as Sears and Midas Muffler and, therefore, may be low.
Jp
The Hunter Publishing data are based on a survey of a cross-section of
facilities. The survey results are projected to give estimates for the whole
industry (Hunter Publishing Co. 1986).
- 130 -
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Table 26. Facilities Where Brake Repair is Performed (1984 Data)
Type
Service
of Facility3
Stations
Independent Repair Shops
New Car
and Truck
Number of
Facilities
115,000
150,000
25,000
Full -Time
Employees
per Facility
(average)
4.3
4.3
19.0
Full-Time
Mechanics
per Facility
(average)
2.6
3.3
8.6
Total
Full -Time
Mechanics13
299,000
495,000
215,000
Dealer Shops
Self-Serviced Fleet 39,000
Shops (with 25 or
more truck-type
vehicles)
Total 329,000
21.5
9.8
382,000
1,391,000
aDoes not include chains such as Sears and Midas Muffler.
"Calculated from average per facility.
Source: Hunter Publishing Co. 1985 and 1986.
- 131 -
-------
We do not use these total estimates of facilities or employees in our
population estimates, however. We have instead chosen an approach which
estimates full-time equivalent (FTE) populations based on the total number c
expected brake replacements. The only information we use from Hunter
Publishing is the distribution of brake jobs among the various types of
service facilities for each friction product and the average number of
full-time mechanics at each of those types of facilities, which allow us to
estimate the number of full-time mechanics indirectly exposed during asbesto
brake servicing (see below). The total number of brake jobs which is used t
estimate FTE populations directly exposed during brake servicing is not
affected by the distribution of brake jobs among the various types of servic
facilities. It is unclear what effect the omission of facilities such as
Sears and Midas Muffler has on the brake job distributions among facility
types.
These facilities employ part-time mechanics and workers in other
capacities not involving auto repair in addition to full-time mechanics. No
information is available on the number of hours worked by part-time mechanic
or exposure to non-mechanics; therefore, we are not able to estimate potenti.
exposure to part-time or non-mechanic employees. Only full-time mechanics &'
used in estimating the population exposed to asbestos during brake repair.
While other workers might occasionally be exposed to asbestos, full-time
mechanics are likely to be exposed on a regular basis. Some mechanics may dc
no brake work, some may do very little, and others may do brake work
full-time; however, monitoring data indicate that exposure to asbestos may
occur all over the workplace and that workers other than those engaged in
actual brake work may be exposed (NIOSH 1982b). NIOSH (1982b) reports that
according to its studies, all individuals in a workplace may be exposed to th
sane fiber concentrations during a work day. Area monitoring data, shown in
- 132 -
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Table 27, indicate significant asbestos concentrations. The geometric mean of
the area TWA concentrations for the period of time sampled (i.e., during a
brake job) is 0.04 f/cc (the corresponding arithmetic mean is 0.05 f/cc).
This is not significantly lower than the geometric mean for personal samples
for mechanics performing brake jobs; as discussed in Section D.2, the
geometric mean TWA concentration of personal samples for the time of a brake
job was 0.09 f/cc (the corresponding arithmetic mean is 0.15). [The geometric
mean of the area sampling results converted to 8-hour TWA concentrations (see
Table 27) is 0.03 f/cc; the corresponding arithmetic mean area concentration
is 0.04 f/cc.]
From the Hunter Publishing Co. data shown in Table 26, the total
potentially exposed population is 1,391,000, the total number of full-time
mechanics; the actual full-time equivalent population is smaller as discussed
below.
a. Duration of Exposure for One Brake Job
The average length of time estimated for brake jobs (per axle) is
as follows:
• Automobile drum brakes -- 1.5 hours (Chilton Book Co.
1987);
• Automobile disc brakes -- 1.1 hours (Chilton Book Co.
1987); and
• Truck brakes (disc and drum) -- 2.5 hours (see below).
The average length of time given for automobile disc and drum brake jobs are
average times used for estimating labor charges for servicing front pads and
rear linings for rear wheel drive cars, respectively; the time for front wheel
drive cars may vary, but the average is approximately the same (Chilton Book
Co. 1987). For a four-wheel brake job, the time would be 2.5 hours, somewhat
shorter than for front and rear jobs separately, but we have assumed for
simplicity that each axle is serviced separately. The actual time needed for
- 133 -
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Table 27. Area Asbestos Concentration During Brake Servicing
Type of Facility
Auto Brake Service Shop
Sane Shop
Municipal Garage
Same Garage
Municipal Garage
Same Garage
Same Garage
Municipal Garage
Private Fleet Service Garage
Type of Service Performed
Brake
Brake
Brake
Brake
Brake
Brake
Brake
Brake
Brake
Service;
Service;
Service;
Service;
Service;
Service;
Service;
Service;
Service;
Compressed Air-Solvent Mist Cleaning
Compressed Air-Solvent Mist Cleaning
Dry Brush
Dry Brush
Wet Brush
Wet Brush
Wet Brush
Cleaning
Cleaning
Cleaning
Cleaning
Cleaning
Liquid Squirt Bottle Cleaning
Vacuum
TWA
Concentration
(f/cc)
0
0
0
0
0
0
0
0
0
.04
.03
.07
.03
.07
.07
.07
.06
.01
Sample
Time
(minutes )
231
222
414
382
360
360
360
395
378
8-Hour TWA
Concentration
-------
a brake job may vary; for example, NIOSH (1980c) gives 20 minutes per wheel or
90 minutes for a four-wheel job as the average at one facility, while another
NIOSH report (1982b) gives an average of 65 minutes per vehicle at an
automobile brake service facility (without specifying whether this time is for
two wheels or four wheels) and an average of five hours per vehicle at a
municipal garage.
The time needed for truck brake jobs, in particular, may vary enormously.
For this reason, there was no average time available for estimating labor
charges for truck brake jobs, as there was for automobiles. The time for a
brake job for trucks from pick-up truck size up to 1-1/2 tons may be in the
same range as for automobiles, while for 2- to 3-ton trucks the time varies
too much to make an estimate. For a tractor-trailer, it may take an entire
day to do a tandem axle job (Chilton Book Co. 1987). A representative of the
American Trucking Association suggested that a brake job might typically take
somewhere between one and four hours (ATA 1987); therefore, we decided to use
the average of 2.5 hours as a rough estimate.
We assumed that workers would be exposed to asbestos only during the time
brake repair is taking place. It is possible that asbestos could be airborne
for a longer period of time, or that asbestos that has settled could again
become airborne; however, there are no data available to allow for an estimate
of the extended periods for which asbestos levels would be elevated.
b. Full-Time Equivalent Populations
The Hunter Publishing Company's 1985 Service Job Analysis gives an
estimate of the percent of total axle sets of drum brake shoes and disc brake
pads for automobiles and trucks installed in 1984 by the four types of service
facilities listed above. Tzanetos et al. (1987) have estimated annual
replacement sales of asbestos drum brake linings and asbestos disc brake pads
for automobiles and light trucks for the years 1986 to 2000. Based on an
- 135 -
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average four-year life for brakes on automobiles and light trucks, brakes
installed in 1985, the base year for this study, will be replaced in 1989.
have used the replacement sales estimates for 1989 to estimate the number of
brake jobs performed on brake linings and pads produced in 1985. The
estimated, number of brake jobs and the Hunter Publishing data are used to
estimate the number of workers who might be exposed to asbestos during
installation and repair.
As discussed above, all workers in a facility may be exposed to
approximately the same levels of asbestos when a brake job is performed.
Therefore, we believe it is reasonable to assume that when a brake job is
performed in a facility, all mechanics at the facility may be exposed during
the period of the brake job at approximately the same level as the mechanic
performing the brake work. To estimate the number of full-time equivalent
workers exposed, we used the total number of brake jobs, the total number of
workers at facilities where brake jobs are performed, and the estimated
average time for a brake job for each type of brake lining. We also assumed
that all full-time mechanics at the facility where the brake job was performe
would be exposed for the average time of the brake job.
(1) Drum Brake Linings for Automobiles
Tzanetos et al. (1987) estimated replacement sales of asbestos
drum brake linings for automobiles and light trucks as 136,045,000 pieces in
1989, the replacement year for drum brake linings installed in the base year
of 1985. This is equivalent to 34,011,250 axle sets (four lining pieces are
used per axle).
Some brake jobs are performed by consumers who do their own brake repair.
Versar (1987) reports that 9,132,000 people purchased brake linings in 1982.
Assuming that approximately the same number of people buy brake linings
annually and that an axle set each of drum brake linings and disc brake pads
- 136 -
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is included in the purchase, about 9,132,000 drum brake lining axle sets will
be bought and installed by consumers in 1989. Ninety-eight percent of these,
or 8,949,360 axle sets, will be asbestos drum brake linings (Tzanetos et al.
1987). Subtracting the number of asbestos drum brake lining sets installed by
consumers from total replacement sales, approximately 25,061,890 sets will be
installed in the workplace in 1989. We applied the Hunter Publishing Co.
(1985) data on percent of total drum brake shoes replaced by each type of
facility to the total number of sets replaced in the workplace to estimate the
number of drum brake shoe sets replaced by facility type.
Table 28 presents the breakdown by facility type of the sets of drum brake
shoes (axle sets) installed. To estimate full-time equivalent workers, we
assumed that each brake job would take 1.5 hours (the average for rear brake
linings) and calculated the total time in hours spent on brake jobs at each
type of facility. We calculated the number of full-time equivalent workers
engaged in brake jobs by dividing the total time in hours by 2,000 (one
working year). As discussed earlier, all workers in a workplace may be
exposed to asbestos; therefore, to estimate the number of full-time equivalent
workers exposed, we multiplied the number of full-time equivalent workers
actually engaged in brake work by the number of full-time mechanics per
facility (see Table 26). The results of our calculations are shown in Table
28. A total of approximately 71,395 full-time equivalent workers is exposed
to asbestos during automobile drum brake shoe repair.
(2) Disc Brake Linings for Automobiles
Tzanetos et al. (1987) estimated replacement sales of asbestos
disc brake pads for automobiles and light trucks as 96,273,000 pieces, or
24,068,250 axle sets (four pads per axle), in 1989, the year of replacement
for disc brake pads installed in 1985.
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Table 26. Automobile Drum Brake Shoe Repair by Facility Type and
Estimated Full-Time Equivalent Workers Exposed to Asbestos
1
H-1
oo
i
Type of Facility
Service Station*
Independent Repair
Shop*
New Cer and Truck
Dealer*
Self-Serviced Fleet
Shop* (with 25 or
more truck -type
vehicle*)
Total
Percent of Total
Number of Drum Brake Shoes
Facilities Installed
(1984) (1964)
115,000 39.0
150,000 46.8
25,000 12.6
39,000 1.6
329,000
Number of
Drum Brake Shoes
Time Spent on
(Axle Sets) Installed Drum Brake
as Replacements
(1989)
9,774,140
11,728,960
3,157,800
400,990
25,061,690
Jobs Per gear
(hours )
14,661,210
17,593,440
4,736,700
601,490
37,592,840
Full-Time ' Estimated Full-
Mechanics Time Equivalent
Estimated Full-Time
Equivalent Workers
Doing Brake Jobs
7,331
8,797
2,368
300
18,796
Per Workers Exposed
Facility to Asbestos from
(average) Drum Brake Jobs
2.6 19,060
3.3 29,030
8.6 20,365
9.8 2.940
71,395
*The average length of time to install a set of drum brake shoes 1* 1.3 hours.
A full-time working year la 2,000 hours.
°Results rounded because of uncertainties in the data.
Sources: Hunter Publishing Co. 1985 and 1966, Tcanetos et al. 1987.
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Versar (1987) reports 9,132,000 consumer purchases of brake linings in
1982. Assuming that this number remains approximately the same in 1989, and
that each consumer buys an axle set of both drum brake linings and disc brake
pads, 9,132,000 sets of disc brake pads will be replaced by consumers. About
65 percent of these," or 5,935,800, will be asbestos disc brake pads (Tzanetos
et al. 1987). Thus, approximately 18,132,450 disc brake pads (axle sets) will
be installed in the workplace in 1989. Using this total for replacement brake
sets and the Hunter Publishing Co. (1985) estimates of percent of disc brake
axle sets installed by each type of facility, we estimated the number of disc
brake axle sets installed by facility type. These estimates are shown in
Table 29.
We used 1.1 hours, the average length of time for a front brake pad job
(ChiIton Book Co. 1987) to calculate the total time spent installing asbestos
disc brake pads annually. We used the same methodology used for drum brakes
to estimate the number of full-time equivalent workers exposed to asbestos
during automobile disc brake repair; the results of our calculations are shown
in Table 29. Ve estimate a total of approximately 38,890 workers exposed to
asbestos during automobile disc brake pad repair work.
(3) Drum Brake Linings for Trucks
ICF Market Survey (1986-1987) estimated that 4,570,266 brake
blocks (drum brake linings for heavy vehicles) were produced in 1985. Heavy
vehicles use four brake blocks per wheel (ICF 1987) or eight brake blocks per
axle; therefore, about 571,280 axle sets were produced in 1985.
Truck brake blocks are assumed to need replacement every six months;
therefore, all brake blocks installed in 1985, the base year for this study,
will be replaced in 1985 (i.e., there is no lag time). It is assumed that
there is no replacement of brake blocks by consumers and that all the brake
blocks produced are used for replacement. Therefore, approximately 571,280
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Table 29. Automobile Disc Brake Fad Repair fay Facility Type and
Estimated FuLl-Tima Equivalent Workers Exposed to Asbestos
Number of
Full-Time Estimated Full-
Percent of Total Disc Brake Pads Time Spent on Mechanics Time Equivalent
Disc Brake Sets (Axle Sets) Installed Disc Brake Estimated Full -Time Per Workers Exposed
Hunter of Installed as Replacements Jobs Per Year Equivalent Workers Facility to Asbestos from
Type of Facility Facilities (1984) (19S9) (hours) Doing Brake Jobs (average) Disc Brake Jobs0
Service Stations 115.000 37.8 6, 854,070 7,539,460 3,770
Independent Repair 150,000 46.2 8.377,190 9,214,910 4.607
Shops
Ne« Car and Truck 25,000 14.6 2,647,340 2,912,070 1,456
Dealers
Self-Serviced Fleet 39,000 1.4 253,850 279,240 140
Shops (with 25 or
more truck-type
vehicles)
Total 329,000 18,132,450 19,945,700 9,973
2.6 9.800
3.3 15,200
8.6 12,520
9.8 1,370
38,890
"The average length of time to install a set of disc brake pads la 1.1 hours per axle.
bA full-time working year la 2,000 hours.
°R«sults rounded because of uncertainties in the data.
Sources: Hunter Publishing Co. 1985 and 1986, Tzanetos et al. 1987.
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brake blocks (axle sets) were replaced in 1985. We used this total and the
Hunter Publishing Co. (1985) estimates to estimate the number of truck drum
brake lining axle sets installed by facility type.
Table 30 shows the total number of sets of truck drum brake linings and
the number of asbestos linings installed annually by facility type. We
assumed that each brake job would take 2.5 hours (note that there are large
uncertainties associated with this estimate) and used the same methodology
used for automobile drum brakes to estimate the number of full-time equivalent
workers exposed to asbestos during truck drum brake lining repair. The
results of our analysis are shown in Table 30. We estimated a total of
approximately 3,832 full-time equivalent workers exposed to asbestos during
truck drum brake repair.
(4) Disc Brake Pads for Trucks
ICF Market Survey (1986-1987) estimated production of asbestos
disc brake pads for heavy vehicles as 156,820 pieces or 19,600 axle sets
(eight pieces per axle) in 1985. Disc brake pads for heavy vehicles need
replacement about every six months; therefore, all disc brake pads for heavy
vehicles installed in 1985, the base year for this study, will be replaced in
1985 (i.e., there is no lag time). It is assumed that no replacement of brake
pads is done by consumers, and that all pads produced in 1985 were used for
replacement. Thus, 19,600 disc brake pads (axle sets) were replaced in 1985.
We used this total and the Hunter Publishing Co. (1985) estimates to estimate
the number of heavy vehicle disc brake pad axle sets installed by facility
type.
Table 31 shows the breakdown by facility type of the sets of truck disc
brake pads (axle sets) installed. We assumed, as for brake blocks, that each
job would take 2.5 hours. We used the same methodology as for automobile drum
brakes to estimate the number of full-time equivalent workers exposed to
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Table 30. Truck Drum Brake Lining Repair by Facility Type and
Estimated FuU-Time Equivalent Workers Exposed to Asbestos
Type of Facility
Service Stations
Auto Repair Shops
New Car and Truck
Dealer*
Salt-Serviced Fleet
Shops (with 25' or
more truck-type
vehicles)
Total
Number of
Facilities
115,000
ISO. 000
25,000
39,000
329,000
Percent of Total
Truck Drum Brake
Linings Installed
(1984)
21.7
41.7
13.0
23.6
Number of Asbestos
Drum Brake Linings
(Axle Sets) Installed
as Replacements
(1985)
123,970
238,230
74,260
134,820
571,280
Time Spent
on Truck
Drum Brake
Jobs Per Year
(hours)
309,920
595,580
185,650
337,050
1,428,200
Estimated Full-Time
Equivalent Worker*
Doing Brake Jobs
155
298
93
168
714
Full-Time
Mechanics
Per
Facility
(average)
2.6
3.3
8.6
9.8
Estimated Full-
time Equivalent
Workers Exposed
to Asbestos
from Truck
Drum Brake Jobs
403
983
800
1,646
3,832°
aThe average time per axle for a truck brake job is roughly 2.5 hours.
bA full-time working year is 2,000 hours.
°Results rounded because of uncertainties in the data.
Sources: Hunter Publishing Co. 1985 and 1986, ICF Market Survey 1986-1987, ICF 1987.
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Table 31. Truck Disc Brake Pad Repair by Facility Type and
Estimated Full-Time Equivalent Workers Exposed to Asbestos
OJ
Type of Facility
Service Stations
Auto Repair Shops
New Car and Truck
Dealers
Self-Serviced Fleet
Shops (with 25 or
more truck -type
vehicles)
Total
Number of
Facilities
115,000
150,000
25,000
39,000
329,000
Percent of Total
Truck Disc Brake
Pads Installed
(1984)
27.0
45.6
17.0
10.4
Number of Asbestos
Disc Brake Pads
(Axle Sets) Installed
as Replacements
(19B5)
5.290
8,940
3,330
2,040
19,600
Time Spent
on Truck
Disc Brake
Jobs Per Year
(hours)
13,220
22,350
8.330
5,100
49,000
Estimated Full-Tlme
Equivalent Workers
Doing Brake Jobs
7
11
4
3
25
Full-Tine
Mechanics
Per
Facility
(average)
2.6
3.3
8.6
9.8
Estimated Full-
Time Equivalent
Workers Exposed
to Asbestos
from Truck
Disc Brake Jobs
18
36
34
29
117°
*The average time per axle for a truck brake job is roughly 2.5 hours.
A full-time working year is 2,000 hours.
cResults rounded because of uncertainties in the data.
Sources: Hunter Publishing Co. 1985 and 1986, ICF Market Survey 1986-1987, ICF 1987.
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asbestos during repair of disc brake pads in heavy vehicles. The results of
the calculation are shown in Table 31. We estimated a total of approximately
117 full-time equivalent workers exposed to asbestos during truck disc brake
repair.
4. " Freouencv and Duration of Exposure
Since the analysis uses full-time equivalent populations, the
frequency and duration of exposure are 250 days/year and 8 hours/day (the
assumed full-time work year), respectively.
5. Summary
The total exposed population for brake repair, in full-time equivalent
workers, is estimated to be about 114,234. (This figure is based on
projections and estimates and should be considered approximate.) The
breakdown by product type is as follows:
• Drum brake linings for automobiles -- 71,395 full-time
equivalent workers;
• Disc brake linings for automobiles -- 38,890 full-time
equivalent workers;
• Drum brake linings for trucks -- 3,832 full-time equivalent
workers; and
• Disc brake pads for trucks -- 117 full-time equivalent
workers.
This total takes into account not only workers engaged in brake work, but all
full-time mechanics in the workplace at the time brake work is performed,
because there is evidence suggesting that such workers may also be exposed to
asbestos at comparable levels.
The projected exposure level during repair for all brake products (data
showing variations by product type are not available) is estimated to be
0.09 f/cc, the geometric mean TWA exposure level during brake servicing using
various brake cleaning methods weighted by the fraction of facilities
estimated to use each cleaning method. The weighted arithmetic mean TWA
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exposure level during brake serviing is 0.15 f/cc. This exposure level may be
rather high for workers not actually engaged in brake work, but evidence
indicates that exposure levels for such workers may not be a great deal lower
than for those actually performing the brake work.
Implicit in the estimate of full-time equivalent workers is a frequency
and duration of exposure equal to 250 days/year and 8 hours/day (the assumed
full-time work year), respectively.
E. Construction Industry Exposure
Due to the many favorable characteristics and uses of asbestos, the
construction industry is the principal market for asbestos materials and
products in the United States. This industry accounted for more than
two-thirds of the total asbestos demand in 1980, and for 50 percent of the
demand in 1984 (OSHA 1986b). Historically, construction materials and
products containing asbestos fibers have included asbestos/cement (A/C) sheets
and pipes, vinyl-asbestos floor tiles, papers, insulation, coatings and
sealants. Since the early 1970s, however, the overall demand for these types
of products has declined due to the availability of adequate substitutes, and
the increased regulatory requirements and restrictions. This declining demand
has continued through the present and, as a result, several asbestos products,
which have traditionally been used in the construction industry, are no longer
produced or sold in the U.S. Some of these construction products that have
'largely disappeared from the U.S. marketplace are vinyl-asbestos floor tiles,
flooring felt, insulation materials, electrical insulation, rollboard, and
other paper products. (Available exposure data and population factors for
vinyl-asbestos floor tile and flooring felt construction activities are
presented in Appendix A.)
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Currently, exposure to asbestos occurs in the construction industry due to
the handling of A/C pipe, A/C sheet (flat and corrugated), A/C shingle,
roofing felt, and roof coatings and cements.
Exposure to asbestos in the construction industry occurs during several
activities.- First, exposure can occur during new construction. Although
concerns about the potential health hazards of asbestos have curtailed its use
substantially, new construction activities continue to account for the
majority of the consumption of asbestos materials (Anderson et al. 1982).
These activities are classified as "installation" operations.
Second, many building owners or managers and industrial firms are
performing asbestos abatement projects. This involves the removing and/or
encapsulating of asbestos materials in existing buildings. Third, renovation
work in office buildings, schools, hospitals, residential and commercial
buildings, and industrial plants may release asbestos fibers. This is due to
the widespread use of asbestos in construction prior to recent years resulting
in the existence of substantial amounts of asbestos materials in existing
building stock. Fourth, routine maintenance and repair activities may also
involve disturbance of asbestos material. Finally, demolition of all or part
of a building also disturbs the asbestos materials causing possible fiber
release. These latter four activities (i.e., abatement, renovation,
maintenance, and demolition) are all classified as "removal" operations.
Although there are a large number of uses and activities involved in the
application of asbestos products in construction, there is only a limited
amount of data concerning exposure to asbestos fibers during construction
projects. Furthermore, the available exposure data is quite old, dating back
to the 1970's in most cases.
One recent source that has been utilized and scrutinized in great detail
is a collection of health sampling results by inspection received from the
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Occupational Safety and Health Administration (OSHA 1987). This information,
provided in the form of a computer-file printout, consists of approximately
1,100 individual inspections conducted by OSHA compliance officers between
1979 and 1986. Each inspection summary provides detailed information on the
location of the surveyed establishment, the date of the inspection, the job
titles of the potentially exposed workers, the number of similarly exposed
workers, as well as the exposure measurements (e.g., sample types, measurement
types, exposure values); in many cases there are up to ten distinct exposure
values given in a single inspection. Nevertheless, these inspection reports
fail to furnish some vital information; the specific asbestos products used
are not ascertainable via the data supplied. The only clues given to identify
the asbestos product used are the 4-digit SIC (standard industrial
classification) codes for which the work falls under and the workers' job
titles. This limited descriptive information is too general to identify the
specific products to which workers were directly or indirectly exposed; only
four specific inspections could be identified as applicable to this study.
OSHA regional and area offices were contacted in an attempt to determine the
specific asbestos product under inspection in each of these four inspections.
Because these OSHA offices keep this detailed material on file for only three
to four years following the actual inspection (subsequently the reports are
archived), information was available for only one of these inspections.
Hence, only one inspection report could be used, for A/C shingle removal, for
this analysis (Durham 1987).
Information is available on most of the germane asbestos products used in
the construction industry: A/C pipe, A/C sheet (flat and corrugated), A/C
shingle, and built-up roofing. Each of these products have several end uses.
For the analysis of A/C sheet removal, the absence of data necessitated the
utilization of exposure information on drywall removal. Drywall is actually
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one specific end use, or application, of A/C sheet; hence, "drywall" may be
considered a subset of the A/C sheet category and serves as a surrogate for
exposure during all other applications. A/C sheet is also used as roofing,
siding, curtain walls, insulating board, and trim (OSHA 1986b).
A similar methodology is applied to the analysis of roofing felt and roof
coatings/cements. Both of these items could be considered distinct product
categories. However, due to the lack of data (particularly regarding the
number of exposed workers) these two products are assessed together under the
categorization of "built-up roofing."
The data for each product category are analyzed in terms of two activity
classifications, installation and removal.
1. Exposure Settings and Operations
Asbestos-cement (A/C) pipe was the greatest single user of asbestos ir
1981 (CONSAD 1984). This product category continued to consume the most
asbestos fiber in 1985 (ICF Market Survey 1986-87). Most of its use is
distributed in the southwestern U.S. for use in sewer systems. Its
installation involves laying pre-cut segments of pipe in a pre-dug trench and
connecting them with various joints. Exposure to asbestos fibers occurs when
a pipe segment must be cut to fit into a specific space (hook-up for home or
business); hand or power tools are used for this purpose. If repair is
needed, a certain segment (corresponding to a standard pipe length) would be
cut out, and a new segment would be installed.
Sheet material is also made from asbestos-cement. Manufacturers cut the
sheet into standard 4'x 8' sheets, or smaller if requested. Flat A/C sheet is
used as drywall and sometimes roofing, siding, and insulation in various
industrial, agricultural, and commercial settings. (Flat A/C sheet is also an
important component in laboratory fume hoods and surfaces because of its
resistance to corrosion.) Corrugated A/C sheet is used mainly in industrial
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and agricultural applications, serving as siding and roofing for factories,
warehouses, and agricultural buildings. It is also used as a lining for
waterways and canal bulkheads, and for special applications in cooling towers.
Installers sometimes have to cut the sheet into smaller segments than those
sold by primary manufacturers. Cutting segments and drilling holes can be a
source of fiber exposure during installation. Removal of drywall is
accomplished by destruction of the wall; this would generally be done during a
building demolition or major renovation.
Roofing material can also be made of A/C sheet. A/C shingles, as they are
called, are used on sloped residential and commercial roofs (CONSAD 1984).
OSHA (1986b) claims that A/C shingle is no longer used in new construction,
but it is used for replacement in existing buildings. Removal and repair of
A/C shingle is accomplished by shattering the old shingle and hammering in a
new one. Asbestos dust release can be expected from this operation.
Built-up roofing is used on commercial buildings with flat, horizontal
roofs. Asbestos roofing felt is mixed with asphalt or tar and installed in
layers. Cutting of the felts with knives or scissors is sometimes necessary
prior to installation; this operation can be a source of exposure for roofing
workers. Built-up roofing is normally left in place for a period of decades.
Over this time, some of the roofing material may become brittle, which in turn
may cause release of fibers upon removal. For the most part, however, most of
the fibers are contained in asphalt or tar, leading to lower exposures during
removal than for installation. Removal is accomplished by means of circular
saws or axes.
Built-up roofing also involves use of another asbestos product, roof
coatings/cements. Roof coatings are used in waterproofing (installation) and
covering cracks (repair). These compounds are manufactured as sprays, pastes,
and other trowel-applied compounds (Anderson et al. 1982). The greatest
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chance for occupational exposure would exist during spraying applications.
Although up to 90 percent of roof coatings are applied using a trowel or
brush, some roofing contractors currently spray the material from either a
truck or a compressed-liquid container (Rose 1987).
Plumbing and boiler maintenance (as well as heating, ventilation, and air
conditioning (HVAC) and lighting repair) can also be sources of asbestos
exposure if these systems are located in close proximity to old asbestos
ceiling tiles or insulation. However, asbestos ceiling tiles and insulation
have not been used in new construction for many years now, so these exposure
classifications are not covered in this analysis.
2. Pre-0.2 f/cc PEL Exposures
Various studies have been performed on construction-related (and
other) industries to determine exposure to asbestos products during
installation, repair, and removal. Table 32 summarizes these current
exposures. Samples were analyzed with phase-contrast microscopy.
Both geometric and arithmetic means of the raw exposure data are presented
in Table 32. For the purpose of these calculations, all short-term TWA data
points that have a value of zero (i.e., 0.0 f/cc) are assumed to be equivalent
to 0.05 f/cc. A zero count merely means that the count was too low for any
fibers to be seen in the counting fields; these "non-detectable" levels are
consistent with very low, but rarely actually zero, concentrations of airborne
fibers. Hence, the use of 0.05 f/cc values where 0.0 f/cc values are recorded
is chosen to enable geometric and arithmetic mean values to be calculated as
it appears to be the limit of detection for the affected construction studies.
Asbestos-cement pipe unloading and laying causes little fiber exposure
(CONSAD 1984). The greatest amount of exposure occurs during pipe-cutting
operations, especially when power tools are used. No exposure data exist for
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Table 32. Pre-0.2 f/cc PEL Exposures to Asbestos Products
in the Construction Industry
Product
A/C Pipe Installation
A/C Sheet (Flat and Corrugated)
Installation
A/C Sheet (Flat and Corrugated)
Removal
A/C Shingle Installation
A/C Shingle Removal
Built-up Roofing Installation
Built-Up Roofing Removal
Short-Term
Level
Geometric
Mean
0.080b
0.215°
1.360d
0.0466
0.084f
0.128g
0.072h
TWA Exposure
Arithmetic
Mean
0.114b
0.405C
0.640d
0.0506
0.094f
0.1598
0.114h
8 -Hour TWA Exposure
Leve). (f/cc)a
Geometric
Mean
0.038b
0.148°
0.340d
0.0106
0.012f
0.032s
0.009h
Arithmetic
Mean
0.058b
0.195C
0.410d
0.0116
0.013f
0.0428
0.015h
aExposure estimates are calculated geometric and arithmetic means of all of
the available exposure data for each product and operation.
^Equitable Environmental Health 1977.
CNIOSH 1979a, NIOSH 1981a.
1986b, CONSAD 1984. Assumed a 2-hour job duration to calculate the
short-term TWA.
eNIOSH 1985a.
%IOSH 1985a, OSHA 1987.
SAnderson et al. 1982, based on data from Johns -Manville studies, reported in
Fenner 1980.
hAherne 1980, Anderson et al. 1982, Lebel 1985.
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A/C pipe repair or removal; therefore, exposure for A/C pipe removal is not
analyzed.
A/C sheet (flat and corrugated) material is installed as siding and
roofing. Dust exposure is highly dependent on the use and control of power
tools in such operations. Anderson et al. (1982) give a short-term exposure
figure of <0.2 f/cc for A/C sheet installation when proper dust collection
devices are attached to power tools, citing studies by Nilfisk (Argonne
National Laboratory 1981) and Johns-Hanville. The lack of dust collection
systems has been shown to lead to short-term exposures of >2 f/cc, according
to studies by Cogley et al. (1981) and Rodelsperger (Anderson et al. 1932).
Our current exposure estimates are based on two NIOSH studies focusing on the
potential exposure to carpenters during the sawing and handling
of asbestos sheetboard used for enclosing air conditioning and physical plant:
(NIOSH 1979a) and for building patios and balconies (NIOSH 1981a). It should
be noted that cutting and drilling operations constitute only a small fractioi
of an A/C sheet installer's time.
No exposure data are available for the removal of general A/C sheet
material. Information is available, however, for the removal of asbestos
drywall, one application of A/C sheet. For demolition and repair (i.e.,
removal) of drywall, OSHA gives unsourced exposure numbers of 0.34 f/cc and
0.75 f/cc, respectively. CONSAD gives figures of 0.41 f/cc and 0.13 f/cc for
demolition and cutting activities, respectively. These values are used to
generate the geometric and arithmetic mean values presented in Table 32 for
A/C sheet removal. Because no actual data are available for this sector, the
short-term TWA value is estimated assuming A/C sheet removal requires
approximately 2 hours of work per day. Exposures during installation and
removal of flat and corrugated A/C sheet products are assumed to be identical.
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Breathing zone samples analyzed during the removal of an old asbestos
shingle roof from a residential building and the installation of a new
asbestos shingle roof are reported in a recent NIOSH report (NIOSH 1985a).
All members of the tear-off and clean-up crews wore half-face respirators with
high efficiency particulate filters (NIOSH 1985a). Asbestos exposure data for
A/C shingle removal are also available for an inspection performed by the
Occupational Safety and Health Administration (OSHA 1987). This planned
inspection, carried out from November 1983 to January 1984, involved roofers
tearing off old shingles from an apartment house in Waycross, Georgia (Durham
1987). The sampling times are not provided for these OSHA values, thus, 2
hours per day is assumed to be the duration of worker exposure during A/C
shingle removal (NIOSH 1985a).
Exposures to asbestos during construction with roofing felt products are
expected to be greatest during installation, as opposed to during repair or
removal. Once built-up roofing has been installed, the fibers are bound with
the tar or asphalt in which they are saturated (Anderson et al. 1982, CONSAD
1984, OSHA 1986b); this proves to be the case for current exposures. As
discussed earlier, the geometric and arithmetic mean calculations assume that
short-term TWA data points recorded as 0.0 f/cc are 0.05 f/cc (based on the
limit of detectability of the sampling methods utilized). Additional data are
also available for the removal of asbestos built-up roofing from a high school
in Louisiana (Lebel 1985) and from a series of unidentified sites (Aherne
1980).
Coatings and sealants are also applied to built-up roofing as
waterproofing material. The occupational exposure for roof coatings during
construction is analyzed jointly with roofing felt under the categorization of
built-up roofing.
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3. Projected Post-0.2 f/cc PEL Exposures
Reduction of the PEL for asbestos from 2 f/cc to 0.2 f/cc means that
increased worker protection will be required in industries where asbestos is
still used. In the construction industry, many companies are small operators
who cannot afford extensive protective gear (such as respirators) or some of
the more sophisticated power tools with dust collection systems. For all
product categories and activities, the projected exposures are based on the
assumption that all raw data points greater than 0.2 f/cc are adjusted to
exactly 0.2 f/cc. This reduction may occur via the utilization of engineer in
controls (e.g., tool shrouding) or the use of respirators. This approach
yields conservative estimates of projected post-0.2 f/cc PEL exposures; the
projections are presented in Table 33.
Current exposure to asbestos from A/C pipe installation is below the 0.2
f/cc limit; only during pipe-cutting are large numbers of fibers released.
Therefore, the projected exposure equals the current exposure level.
A/C sheet and shingle installation can lead to asbestos exposure during
cutting and drilling operations. Proper shrouding of tools and dust
collection systems can reduce the estimated current exposure level for A/C
sheet installation. The data suggest only a small reduction in overall
exposure levels for A/C sheet installation because most of the existing data
are below the 0.2 f/cc level. No exposure reduction is projected for A/C
shingle installation or removal since all of the existing data are already
below 0.2 f/cc.
Drywall demolition and repair involves cutting and/or shattering sections
of A/C sheet. Repair and removal workers could easily be exposed to dust
levels for a longer period of time than installation workers. OSHA (1986b)
recommends use of a half-mask negative-pressure respirator to reduce exposure
by a factor of 10. CONSAD (1984) also recommends use of dust collection
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Table 33. Projected Exposures to Asbestos Products
in the Construction Industry
Post-0.2 f/cc PEL
Short-Term TWA Exposure
Level ff/cc">a
Post-0.2 f/cc PEL
8-Hour TWA Exposure
Level ff/cc)a
Product
A/C Pipe Installation
A/C Sheet (Flat and Corrugated)
Installation
A/C Sheet (Flat and Corrugated)
Removal
A/C Shingle Installation
A/C Shingle Removal
Built -Up Roofing Installation
Built -Up Roofing Removal
Geometric
Mean
C.080b
0.173
0.800
0.046b
0.084b
0.128b
0.072b
Arithmetic
Mean
0.114b
0.278
0.800
0 . 050b
0.094b
0.169b
0 . 114b
Geometric
Mean
0.038b
0.119
0.200
0.010b
0.012b
0.032b
0.009b
Arithmetic
Mean
0.058b
0.140
0.200
0.011b
0.013b
0.042b
0.015b
Projections are calculated assuming that all 8-hour TWA raw data originally
greater than 0.2 f/cc would be reduced to this limit, and new geometric and
arithmetic means are calculated.
bNo change from the pre-0.2 f/cc PEL exposure.
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systems and wetting agents to keep fiber exposures down. Thus, a substantia
reduction in exposure is expected for A/C sheet removal; this is exhibited b
the lower projected geometric and arithmetic mean, 8-hour TWA values
(0.20 f/cc) compared to the pre-0.2 f/cc PEL geometric and arithmetic mean,
8-hour TWA exposures (0.34 f/cc and 0.41, respectively).
Installation, repair, and removal of built-up roofing material is a sour<
of asbestos fiber exposure (especially installation work). OSHA and CONSAD
both recommend use of half-mask negative-pressure respirators to reduce
exposures during installation by a factor of 10. This protection would also
automatically reduce exposures during application of asbestos roof coatings.
Additional protection is also recommended during removal and repair (tear-off
activities, especially where the roofing material has become brittle.
Recommendations for further exposure reduction included wetting the roof prio
to removal; evacuating the building occupants if feasible; sealing off all
doors, windows, and other openings; and proper handling of workers' clothing
(NIOSH 1985a). No exposure reduction is projected for built-up roofing
installation or removal, however, since all of the existing data are already
below 0.2 f/cc.
4. Populations Exposed
As the production of asbestos-containing products continues to
decline, so will the numbers of exposed workers. Workers in the construction
industry often work with a variety of materials, depending on the needs of the
purchaser. However, a determination can be made of the equivalent number of
workers who would work full-time (8 hours/day and 250 days/year) exclusively
with asbestos. This number, the full-time equivalent (FTE) population, is
based on crew size, productivity, and total production plus imports of the
asbestos product.
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We assumed that workers would be exposed to asbestos only during the time
construction activities are taking place. It is possible that asbestos could
be airborne for a longer period of time or that asbestos that has settled
could again become airborne; however, there are no data available to allow for
an estimate of the extended periods for which asbestos levels would be
elevated. It is also possible that other workers not handling asbestos
products would be in the vicinity during construction activities and would be
exposed to asbestos. Data on the number of people likely to be in the
vicinity during asbestos construction activities and the levels of asbestos to
which they are exposed are not available. It is likely that indirect
exposures to these people would be captured in the ambient exposure
assessment.
In the construction industry, crew sizes can be estimated based on Means
Man-Hour Standards (Means 1983). The construction industry is the biggest
user of asbestos products, so FTE populations are significant.
A/C pipe accounts for the greatest single use of asbestos (ICF Market
Survey 1986-1987). A total of 216,903 tons of pipe, representing 15,062,709
linear feet, was produced or imported in 1985 (ICF Market Survey 1986-1987).
Given an average crew size of 3.5 workers to install piping at a productivity
rate of 228.9 ft of pipe/crew/day (Means 1983) (working 250 days/year), the
FTE population for A/C pipe installation is 921 person-years.
Installation of A/C sheet (flat and corrugated) is analyzed separately
from A/C shingle, since separate production and import quantities have been
n
obtained. A typical crew of four persons can install an average of 877.5 ft'
of A/C sheet in one day (Means 1983). The total 1985 production plus imports
of A/C flat sheet was 856,070 ft2 (ICF Market Survey 1986-1987). Therefore,
the total FTE population for A/C flat sheet installation is 16 person-years
(assuming 250 days/year). The total 1985 imports of A/C corrugated sheet
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(there is no domestic production) was 385,900 ft2 (ICF Market Survey
1986-1987). Therefore, the total FTE population for A/C corrugated sheet
installation is 7 person-years.
A/C sheet removal is based on the ability of a work crew of 3 persons tc
remove and replace 520 ft2 of A/C sheet per day (OSHA 1986b). Assuming all
the 856,070 ft2 of A/C flat sheet produced and imported into the U.S. in 198
(ICF Market Survey 1986-1987) is repaired or replaced after its useful life,
the total FTE population for A/C flat sheet removal is 20 person-years.
Assuming all of the 385,900 ft2 of A/C corrugated sheet imported into the U.
in 1985 (ICF Market Survey 1986-1987) is repaired or replaced after its usef
life, the total FTE population for A/C corrugated sheet removal is 9
person-years.
A total of 17,664,300 ft2 of A/C shingle was produced or imported in 198
(ICF Market Survey 1986-1987). Since this material is usually used in roofii
of residential housing, only one worker is assumed per crew (Means 1983). A
worker can install 300 ft2 of shingle per day (Means 1983). Therefore, the
total FTE population for A/C shingle installation is 236 person-years (using
250 days/year).
A/C shingle removal is assumed to require a 7-person crew, replacing 3,02
ft2 of shingle per day (as for built-up roofing). If all of the A/C shingle
that was produced or imported in 1985 is assumed to be repaired or replaced
after its useful life (i.e., 17,664,300 ft2 of A/C shingle), then the total
FTE population for A/C shingle removal is 164 person-years.
No companies manufacture primary roofing felt in the U.S.; however, one
company imported 1,625 tons of roofing felt in 1985 (ICF Market Survey
1986-1987). Built-up roofing (i.e., roofing felt) can be assumed to weigh
11.5 lb/100 ft2; thus, 28,320,000 ft2 of roofing felt were imported into the
U.S. in 1985 (ICF Market Survey 1986-1987). Roofing felt is normally
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installed by a 7-person crew at a productivity rate of 2,000 ft2/day (Means
1983). Assuming a working year of 250 days, the total FTE population for
built-up roof installation is 396 person-years.
Built-up roofing repair involves a 7-person crew that can replace
3,020 ft2 of roofing per day (OSHA 1986b). Assuming all of the 28,320,000 ft2
of built-up roofing material imported in 1985 (IGF Market Survey 1986-1987) is
repaired or replaced at the end of its useful life, a total of 263 FTE
person-years would be required.
Use of adhesives and sealants can be assumed to be concurrent with use of
built-up roofing felt. No specific productivity data are available, but time
spent applying sealant is probably insignificant compared to the time spent
laying the roofing felt.
The above data are summarized in Table 34.
5. Frequency and Duration of Exposure
In the construction industry, exposure duration and frequency are
effectively 8 hours/day and 250 days/year because full-time equivalent
populations are being used in this analysis. Conceptually, this is a
measurement of the total person-hours of exposure involved (much as
construction jobs require a certain number of man-hours to do the work) and
not the actual number of workers who at some time might install, repair, or
remove asbestos-containing construction materials.
The actual duration of time required to perform the installation and
removal of these asbestos products ranges from approximately two to five hours
per day (Aherne 1980; Anderson et al. 1982; Equitable Environmental Health
1977; Lebel 1985; NIOSH 1979a, 1981a, 1985a; and OSHA 1986b).
6. Summary
Table 35 summarizes FTE populations, projected exposure levels, and
duration and frequency of exposure. The data presented are estimates of the
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Table 34. FTE Populations in the Construction Industry
Workers Annual Consumption
Per Daily (Production +
Job Type Crew Productivity Imports )b
A/C Pipe . 3.5a 228.9 fta 15,062,709 ft
Installation
A/C Flat Sheet, 4a 877.5 ft2a 856,070 ft2
Installation
A/C Flat Sheet, 3C 520 ft2c 856,070 ft2
Removal
A/C Corrugated 4a 877.5 ft2a 385,900 ft2
Sheet,
Installation
A/C Corrugated 3C 520 ft2c 385,900 ft2
Sheet, Removal
A/C Shingle la 300 ft2a 17,664,300 ft2
Installation
A/C Shingle 7C 3,020 ft2c 17,664,300 ft2
Removal
Built-Up Roofing 7a 2,000ft2a 28,320,000ft2
Installation
Built-Up Roofing 7C 3,020 ft2c 28,320,000 ft2
Removal
FTE
Person-
Years
921
16
20
7
9
236
164
396
263
FTE - Full-time equivalent. (Note: All workers assumed to be working 8
hours/day, 250 days/year.)
aMeans 1983.
bICF Market Survey 1986-1987.
COSHA 1986b.
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Table 35. Summary of Occupational Exposure to Asbestos in
the Construction Industry
Projected
Post- 0.2 f/cc
PEL Short -Tern
TWA Asbestos
Job Category
A/C Pipe Installation
A/C Flat Sheet
Installation
A/C Flat Sheet Removal
A/C Corrugated Sheet
Installation
A/C Corrugated Sheet
Removal
A/C Shingle
Installation
A/C Shingle Removal
Built-Uo Roofine
FTE
Population
(person-
years)
921
16
20
7
9
236
164
396
Exposure
Levels
(f/cc)
Geometric
Mean
0.080
0.173
0.800
0.173
0.800
0.046
0.084
0.128
Arithmetic
Mean
0.114
0.278
0.800
0.278
0.800
0.050
0.094
0.169
Frequency and
Duration
of Exposure
8 hr/d, 250 d/yr
8 hr/d, 250 d/yr
8 hr/d, 250 d/yr
8 hr/d, 250 d/yr
8 hr/d, 250 d/yr
8 hr/d, 250 d/yr
8 hr/d, 250 d/yr
8 hr/d, 250 d/yr
Installation
Built-Up Roofing
Removal
263
0.072
0.114
8 hr/d, 250 d/yr
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full-time equivalent exposures of'workers in various construction jobs, based,
on production and imports of the material and worker productivity.
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III.
Emissions measurement data from asbestos processing sources (i.e., mining,
milling, manufacturing, and trade uses) are limited; therefore, it is
necessary to use engineering techniques to estimate asbestos releases to the
ambient air from various processing sources. The technical data base from
which emission estimates are derived contains significant data gaps as well as
other sources of uncertainty that require the use of simplifying assumptions.
Several judgments have been made in the absence of actual data and these are
stated throughout the discussion. Therefore, the results of this analysis
represent estimates given the available data and should be used cautiously.
The emission estimates presented are by no means absolute values.
The methodologies used to estimate air releases and the subsequent
emission estimates are presented for milling and primary manufacturing,
secondary manufacturing, mining and trade uses, and asbestos-containing waste
piles in the following sections. (Descriptions of products and processes are
presented in Chapter II, Occupational Exposure.)
A. Milling and Primary Manufacturing Emissions
1. Methodology
The basic approach for estimating emissions from milling and primary
manufacturing sources is adopted from those used by the EPA Office of Air
Quality Planning and Standards (OAQPS) in establishing a National Emission
Standard for Hazardous Air Pollutants (NESHAP) (OAQPS 1987) and the EPA
Exposure Assessment Branch (EPA 1986a) , with some modifications.
To estimate emission rates from milling and primary manufacturing sources,
the following equation is used (adapted from EPA 1986a) :
„ . . /n wqw 2,000 Ib W454 g 1 year
Asbestos Emission- (l-e)O(_J _ )( _ _) (
hr
_
Rate (g/sec) e 1 short ton Ib 8,760 hrs 3,600 sec
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where, e - estimated collection efficiency of control device (fractional
percent);
q - total quantity of control device waste collected annually (short
tons); and
a - average asbestos content of control device waste (fractional
percent).
The above equation shows that the asbestos emission rate is a function of
the collection or removal efficiency of the control device, the amount of
fiber collected by the control device, and the annual operating hours. The
most comprehensive data base which provides these data elements is the data
submitted to EPA by asbestos manufacturers in response to the Toxic Substances
Control Act (TSCA) Section 8(a) asbestos reporting rule (EPA 1986b). However,
the base year of the reported values is 1981 which is outdated for the present
estimates.
Another data source available is the responses to the "Section 114
letters" provided by EPA's Office of Air Quality Planning and Standards
(Section 114 Letters 1985). In 1985, Section 114 letters were sent to a
selected group of plants determined by OAQPS to be high maximum individual
risk plants. The 114 data provides plant specific parameters on air pollution
control equipment, control device efficiencies, amount of waste collected and
asbestos content of the waste from control devices, operating hours, and
stacks parameters. These data are useful for estimating air releases but are
limited to 9 primary manufacturing plants that are still processing asbestos
(6 friction material plants, 2 reinforced-plastic plants, and 1 asbestos-
cement product plant) and one milling facility.
A final data source available is the responses to the ICF Exposure Survey
(1986-1987). The ICF Exposure Survey was sent to all the companies
manufacturing asbestos or asbestos products. This survey contained a section
on stack data that was modeled after OAQPS' Section 114 Letter. Seven
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companies provided detailed stack data for eight asbestos processing plants
(1 paper plant, 1 A/C pipe plant, 2 friction material plants, 1 textile plant,
1 adhesive and sealant plant, and 2 chlorine plants) and one milling facility.
In addition, four other plants (2 friction material plants and 2 adhesive and
sealant plants) provided data on the quantities of baghouse waste collected
but did not provide stack-specific information such as stack dimensions, and
exhaust gas flow rates and temperatures.
Due to limited data availability, many inputs to the emission rate
equation must be estimated; the derivation methods are discussed below.
a. Qperatine Schedule
The annual operating schedule at any plant is assumed to be 8,760
hours (i.e., 24 hours per day and 365 days per year). Most manufacturing
plants operate less than 8,760 hours per year (close to 6,000 hours); however,
air pollution control systems may operate continuously (PEI Associates 1986).
As a result, a steady-state release rate is estimated over an entire year.
b. Quantity of Asbestos Collected by the Control Device
The quantity of asbestos fibers collected by the control device is
equal to the total quantity of waste collected times the asbestos content in
the waste. The quantity of waste collected is derived by calculating the
ratio of waste collected by the control device in 1981 (EPA 1986b) to asbestos
fiber consumed in 1981 (EPA 1986b) , and applying this ratio to the amount of
fiber consumed in 1985 (ICF Market Survey 1986-1987). This proportioning
method, introduces errors to the emission estimates because the Section 8(a)
data (non-CBI version -- aggregated data) gives quantity data per asbestos
product category instead of per plant. Asbestos manufacturers employ slightly
different operating and housekeeping procedures from plant to plant thereby
generating different waste quantities. However, this approach provides a
rough estimation of the waste quantity generated. In conjunction with Section
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8(a) data, Section 114 data (1985) and ICF Exposure Survey (1986-1987) data or
waste are also used when available.
The average asbestos content in the waste is available from Section 8(a),
Section 114, and ICF Exposure Survey data (EPA 1986b, Section 114 Letters
1985, ICF Exposure Survey 1986-1987). Again, the Section 8(a) aggregated date-
gives asbestos content data per asbestos product category rather than per
plant.
c. Collection Efficiency of the Control Device
The major types of collection devices available are cyclones, wet
scrubbers, electrostatic precipitators, and fabric filters (commonly referred
to as baghouses). Each of these control devices has some applicability in the
asbestos industry; however, data collected under TSCA Section 8(a) shows that
baghouses are the predominant method (more than 90 percent) for controlling
asbestos releases to the ambient air (EPA 1986b, OAQPS 1987). This analysis
assumes that baghouses are the control device used by all manufacturing
plants.
As noted from the emission rate equation, collection efficiency is the
variable that is primarily responsible for determining the magnitude of the
asbestos emission. Unless the collection efficiency estimates are accurate to
three or more significant figures, emission rates will vary by orders of
magnitude. For example, an estimate of 99.90 percent collection efficiency
and one of 99.99 percent will alter emission rates by a factor of 10. The
control device efficiencies reported by individual plants in 1981 and those
that responded to the Section 114 Letters or the ICF Exposure Survey were
based on vendor supplied estimates or design criteria and are often presented
as 99+ percent or 99.9+ percent (EPA 1986b, OAQPS 1987, Section 114 Letters
1985, ICF Exposure Survey 1986-1987). Due to the sensitivity of air release
estimates with respect to the efficiency of the control device, it is
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necessary to estimate collection efficiency to four significant figures.
Since the Section 8(a) data on collection efficiencies is insufficient and has
a high degree of uncertainty, it is necessary to develop more reasonable
efficiency estimates based on an engineering approach; such an approach was
developed by OAQFS and is used in this analysis.
OAQPS's methodology to estimate asbestos air releases is presented in the
March 5, 1987 draft report entitled "National Emission Standards for Asbestos
-- Background Information for Proposed Standards" (OAQPS 1987). OAQPS
presents three emission scenarios: minimum, maximum, and "best estimate"
emissions. The normal mode efficiency for baghouses is 99.99 percent for the
minimum and best estimate emission scenarios. The maximum emission scenario
gives two average baghouse efficiencies: 99.95 percent for asbestos product
categories with high inlet concentrations (greater than 0.1 grain/cu ft) and
99.67 percent for product categories with low inlet concentrations (less than
0.1 grain/cu ft) (OAQPS 1987). The asbestos product categories with high
inlet concentrations are asbestos-cement sheet and pipe, friction materials,
and reinforced plastics; those with low inlet concentrations are paper,
coatings and sealants, packings and gaskets, and textiles.*
As a comparision between the minimum and maximum emission scenarios, a
collection efficiency of 99.95 percent compared to one of 99.99 percent
changes the emission rates 5-fold, and a collection efficiency of 99.67
percent compared to one of 99.99 percent affects the emission rates by
approximately 33-fold.
To estimate air releases from primary manufacturing sources, efficiency
estimates under the maximum emission scenario are chosen for this analysis.
It is believed that these efficiency estimates (99.95 percent and 99.67
* For additional information on the derivation of inlet/outlet concentra-
tions and collection efficiencies, see Appendix B of the OAQPS (1987) report.
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percent) are reasonable estimates. The selection of these efficiency
estimates is based on a conservative approach. The collection efficiency of
99.99 percent under the minimum and best estimate emission scenarios is
achievable; however, it may represent best demonstrated efficiency under
optimum operating conditions rather than conditions that are typically found
during normal operating mode at the asbestos plants. A well designed air
pollution control system may have very high removal efficiency1, but gradual
deterioration of the equipment and improper operation and maintenance can lead
to a decrease in its removal efficiency (IIT Research Institute 1981). No
attempt is made to re-estimate the collection efficiences developed by OAQPS
since it is very difficult to refine these values further without actual test
data. In actuality, many factors may influence the collection efficiency of a
fabric filter system such as the dust properties (i.e., particle size
distribution and concentration), fabric properties, operating parameters
(i.e., pressure drop, gas volume, gas velocity, etc.), and filter cleaning
method (IIT Research Institute 1981). These parameters are different for each
manufacturing plant; therefore, it is not possible to predict quantitatively
the performance of a filter system with much more confidence. The generalized
approach above introduces some uncertainties into the estimation of air
releases, and this should be realized in estimating the downstream exposure.
Emission estimates by OAQPS also take into account both the normal
operating mode efficiencies and the failure mode efficiencies of control
devices. Since the efficiency values chosen are already estimated values with
uncertainties associated with the fourth significant digit, it is not
appropriate to take failure mode efficiency into account (failure mode
efficiency only affects the fourth significant digit). The present estimates,
therefore, ignore this factor.
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2. Emission Estimates
Aggregate asbestos emission estimates from milling and primary
manufacturing sources by product are presented in Table 36.* Although not
presented in Table 36, plant-specific emission estimates and supplementary
data on plant locations and zip codes for each milling and manufacturing
source (ICF Market Survey 1986-1987) were provided to Versar, Inc. to model
ambient exposures. The 1985 asbestos fiber consumption (ICF Market Survey
1986-1987) and the quantity of baghouse waste for each plant used to calculate
emissions were also provided to Versar, Inc. The quantity of baghouse waste
represents the variable "q" in the emission rate equation discussed in Section
A.I above. A number of plants provided the quantity of asbestos fiber
consumed in 1985 but noted that they phased out of asbestos product
manufacture in 1986; asbestos emissions from these plants are not included in
the aggregate emission estimates. Therefore, only primary manufacturers that
are currently (i.e., in 1987) producing asbestos-containing products are
included in the aggregate emission estimates and were provided to Versar, Inc.
for ambient exposure modeling. In addition, there are plants identified as
current producers of asbestos-containing products, but company officials have
refused to provide data. The 1985 asbestos fiber consumption for these
refusal plants are based on estimated values calculated by ICF (ICF Market
Survey 1986-1987).
The quantity of waste collected from the air pollution control devices (q)
is obtained by applying the waste/fiber consumption ratio to the 1985 fiber
consumption. This ratio is calculated from the TSCA Section 8(a) data (EPA
1986b) as discussed earlier; the 1981 fiber consumption and waste information
* Recall that the choice of baghouse collection efficiency greatly affects
the final emission estimates. Emissions could be 5-fold lower for asbestos-
cement sheet and pipe, friction materials, and reinforced plastics and 33-fold
lower for paper, coatings and sealants, packings and gaskets, and textiles.
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Table 36. Asbestos Emissions from Milling and Primary Manufacturing Sources
TSCA 1985 A»be»to»
Identification Consumption
Asbestos Product/Mixture Number ( short tons)"
Raw Asbestos Fiber
Millboard
Pipeline Wrap
Beater-Add Gasketing
High Grade Electrical Paper
Asbestos Diaphragms
A/C Pipe
A/C Sheet. 'Flat
A/C Sheet, Shingles
Drum Brake Linings
Disc Brake Pads (UM)
Brake Blocks
Clutch Facings
Friction Materials
Yarn, Thread, Roving, and Rope
Sheet Gaaketing
Packing
Paints and Surface Coatings
Adheslves and Sealants*
Reinforced Plastics
~
03
04
05
06
13
14
15
17
IB
19
21
22
24
26
27
28
29
30
31
62,070b
435.8
1,333
11,840.4
744
985. 5C
32,690.8
588.8
3,893.0
19,869.0
4,130.7
2,137.1
1,663.0
1.521.8
558.0
5,301.1
1.1
22,215.5
2,082.9
636.1
Total
Asbestos
Content
of Waste1
(short tons)
9.890.98
21.3
42.7
173
81.6
0.1728
1,216.7s
129.5
43.25
6,648.3s
483. 8s
177.9s
269.0s
205.4s
50.5s
100.6
0.065
26.0
0.60s
36.8s
Baghouse Emission
Efficiency Rate
(e) (g/sec)
99. 9i
99.67
99.67
99.67
99.67
99.95
99.95
99.95
99.95
99.95
99.95
99.95
99.95
99.95
99.67
99.67
99.67
99.67
99.67
99.95
1.43E-1
2.03E-3
4.07E-3
1.6SE-2
7.78E-3
2.48E-6
1.75E-2
1.87E-3
6.23E-4
9.58E-2
6.97E-3
2.S6E-3
3.87E-3
2.96E-3
4.81E-3
9.59E-3
6.19E-6
2.48E-3
5.72E-5
5.30E-4
Hours Total
of Operation Emissions
(hr/yr) ,(kg/yr)
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
4,495
64
128
520
245
0.08
552
59
20
3,020
220
81
122
93
152
303
0.2
78
2
17
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TabU 36 (Continued)
*ICF Market Survey 1986-1987 and ICF estimates for non-respondents.
This is the quantity of raw asbestos fiber production from the asbestos mill rather than asbestos consumption.
°The 1985 asbestos consumption for chlorine manufacturers using asbestos diaphragm cells is calculated using the capacity data from Table 21
(converted to "short" tons), the capacity utilization rate (77 percent) from Table 22, and the ratio of asbestos consumption to chlorine
production (0.000125 tons asbestos/ton of chlorine) from Table 22. (See Chapter II, Section C.)
dThls product category has been reclassified as roof coatings and cements (ICF Market Survey 1986-1987).
9Thls product category has been reclassified as non-roofing adhesives, sealants, and coatings (ICF Market Survey 1986-1987).
Estimated from 1985 asbestos consumption and 1981 Section B(a) data (EPA 1986b) on waste-to-consumption ratios and asbestos content (see
Table 37) except as indicated.
'includes facility-specific data reported in Section 114 Letters (1985) or ICF Exposure Survey (1986-1987).
-------
used in the calculation of this ratio are summarized in Table 37. For plants
that responded to Section 114 or the ICF Exposure Survey, the quantity of
asbestos waste reported per control device by each respondent was used to
calculate plant emissions and was provided to Versar, Inc. for input into the
ambient exposure model (Section 114 Letters 1985, ICF Exposure Survey
1986-1987). The base year for the Section 114 reported values is 1984. Tabl
37 also lists the percent of asbestos in the waste for each product category;
this percentage represents the variable "a" in the emission rate equation.
Since chlorine producers using asbestos diaphragms were not surveyed by
TSCA Section 8(a) or the ICF Market Survey (1986-1987), data such as asbestos
consumption and the ratio of baghouse waste to fiber consumption needed to
calculate emissions are not available. However, chlorine plant capacities atu
general industry data on the capacity utilization rate and the amount of
asbestos consumed per ton of chlorine produced are available (see Chapter II,
Section C) and have been used to estimate the asbestos consumption for each
plant. The factor used to estimate the total quantity of baghouse waste is
based on an average of the conversions calculated for the companies that
supplied waste data.
Stack dimensions and the exhaust gas flow rate, velocity, and temperature
were provided to Versar, Inc. as part of the input for the ambient exposure
model. For plants that responded to Section 114 or the ICF Exposure Survey,
all of these parameters except the exhaust velocity* are available. For
plants that did not respond to Section 114 or the ICF survey, the stack
dimensions, gas velocity, and temperature are indicated as not available. It
was possible to estimate the exhaust gas flow rate, however, based on OAQPS's
model plants which were developed for each product category (OAQPS 1987).
The exhaust gas velocity is calculated based on the exhaust gas flow
rate and the cross-sectional area of the stack.
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Table 37. 1981 Primary Manufacturer Asbestos
Consumption and Waste Generation
Asbestos Mixture/
Product
Milling
Millboard
Pipeline Wrap
Beater-Add Gasketing
High Grade Electrical
Paper
A/C Pipe
A/C Sheet, Flat
A/C Sheet, Shingles
Drum Brake Lining
Disc Brake Pads (L&M)
Disc Brake Pads (H)
Brake Blocks
Clutch Facings
Automatic Transmission
Components
Friction Materials
Yarn
Sheet Gasketing
TSCA
ID#
03
04
05
06
14
15
17
18
19
20
21
22
23
24
26
27
1981 Total
Asbestos ,
Consumption
(short tons)
87,817e
898
2,347
26,073
826
59,985
11,062
4,315
20,296
9,021
80
14,924
2,612
143
3,105
4,741
9,544
Total
Quantity of
Baghouse Waste
(short tons)
33,220
53f
89s
492
113g
4,354f
4,400
436h
2,311
2,891
52
3,446
877h
N/A
l,788h
N/A
372
Percent of
Asbestos in
Waste (a)
(%)
5.0
83.0
85.0
76.8
80.0
13.9
55.3
11.0
48.8
47.9
10.9
38.4
32.5
40.0
38.3
N/A
48.8
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Table 37 (Continued)
Asbestos Mixture/
Product
Packing
Paints and. Surface
Coatings
Adhesives and Sealants^
Reinforced- Plastics
TSCA
ID*
28
29
30
31
1981 Total
Asbestos ,
Consumption
(short tons)
1,105
15,036
22,557
2,569
Total
Quantity of
Baghouse Waste
(short tons)
206h
96
16
837
Percent o:
Asbestos :
Waste (a)
(%)
31.7
18.3
21.2
31.3
N/A - Not Available.
aEPA 1986b.
bEPA 1986b (Table 3). This is the total quantity of asbestos consumed per
product category in 1981. The quantities were reported in ranges as "minimum1
and "maximum" quantities; the average value was calculated and reported in
this table.
CEPA 1986b (Table 15). This is the total quantity of baghouse fines, dry
waste. It does not contain 100 percent asbestos fiber.
dEPA 1986b (Table 14). Assumed the percent of asbestos in baghouse waste is
equal to the percent of asbestos in the total waste.
eThis is the fiber production rather than fiber consumption.
^Baghouse waste was not reported. Assumed baghouse waste is equal to the
"miscellaneous" waste reported in EPA 1986b (Table 15).
Sfiaghouse waste was not reported. Assumed baghouse waste is half of the total
waste reported in EPA 1986b (Table 15).
"Baghouse waste was not reported. Assumed baghouse waste is equal to baghouse
fines, wet reported in EPA 1986b (Table 15).
*-This product category has been reclassified as roof coatings and cements (ICF
Market Survey 1986-1987).
JThis product category has been reclassified as non-roofing adhesives,
sealants, and coatings (ICF Market Survey 1986-1987).
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For each model plant, the following plant parameters were estimated: annual
production and capacity, asbestos consumed, solid waste generated, annual
operating hours, and number of baghouses and their flow rates. The basis for
these model plants is the Section 8(a) submittals, site visits, and general
knowledge of the industry (OAQPS 1987, EPA 1987). For a few product
categories, more than one model plant is presented (e.g., small, medium, and
large plants), and the selection of the appropriate model plant is based on
the comparison of the actual fiber consumption level for each plant with those
of the model plants. Where the asbestos consumption rate is much lower than
that of the small model plant, it is assumed that the plant may have to shut
down a production line due to the decreased demand for the product.* Thus,
the number of baghouses is decreased accordingly. When the stack dimensions
and the exhaust gas temperature are not available, default values can be
applied. A 2-foot diameter stack is considered to be typical,** and stack
height normally ranges from 4 to 10 feet above roof level (AIA 1986). Ambient
temperature of 70°F is an appropriate default value for stack exhaust gas
temperature.
Using the total quantity of waste collected from the baghouses (q) for
each plant, the assumed efficiency (e), and the percent of asbestos in the
waste (a) from Table 37, emission rates for each plant are calculated using
the emission rate equation. The result is an emission rate that represents
the total rate of release of asbestos fibers to the ambient air from each
processing source. To determine the asbestos release rate from each control
* This plant may also operate intermittently; however, this assumption is
not used because continuous release rates are being estimated.
** Office of Research and Development (ORD) estimate based on experience
with emissions from coal-fired boilers (OAQPS 1987). (Another source stated
that the stack diameter varies from 1.5 to 5 feet (AIA 1986) but did not
indicate a typical value.)
- 175 -
-------
device (baghouse), this total emission rate is divided by the number of
baghouses at each plant. This is an arbitrary assumption since specific
information about each baghouse is not available. For plants that responded
to the Section 114 letters or the 1CF Exposure Survey, the emission rate is
calculated separately for each baghouse since the inputs to the emission rate
equation were provided for each baghouse. Although only aggregate emission
estimates are reported in Table 36, the plant-specific emission estimates and
supporting data were provided to Versar, Inc. for use in the ambient exposure
model.
Due to lack of data, it is not possible to estimate asbestos emissions foi
a number of primary manufacturing sources. These include primary
manufacturers of specialty paper, asbestos insulation materials (used as
missile liners -- not textile insulation materials), and miscellaneous
products such as acetylene cylinders, sealant tapes, battery separators, and
arc chutes. Commercial paper, rollboard, roofing felt, flooring felt,
corrugated paper, V/A floor tile, and corrugated A/C sheet are no longer
produced in the U.S. (refer to Appendix A for a discussion of emission factors
for these products).
B. Secondary Manufacturing Emissions
1. Methodology
Emission estimates for secondary manufacturing sources are also
derived based on the same emission rate equation used for primary
manufacturing (see Section A.I). Section 114 data (Section 114 Letters 1985)
do not contain information on secondary manufacturers, and none of-the
secondary manufacturers who responded to the ICF Exposure Survey (1986-1987)
supplied stack data (i.e., stack dimensions, exhaust gas flow rate,
temperature). The waste quantity collected from the control devices is
estimated based on the waste-to-mixture consumption ratio calculated from the
- 176 -
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TSCA Section 8(a) aggregated data (non-CBI version) for secondary
manufacturing (EPA 1986b). The operating schedule is assumed to be 8,760
hours per year as in the case of primary manufacturing sources. Control
device (i.e., baghouse) efficiencies are also based on OAQPS's estimates under
the maximum emission scenario which are 99.95 percent and 99.67 percent for
high and low inlet concentration loadings, respectively (OAQPS 1987).
2. Emission Estimates
Aggregate asbestos emission estimates from secondary manufacturing
sources by asbestos mixture are presented in Table 38. Although not presented
in Table 38, plant-specific emission estimates and supplementary data on plant
locations, zip codes, and the quantity of asbestos mixture consumed in 1985
(ICF Market Survey 1986-1987) were provided to Versar, Inc. for input into the
ambient exposure model. In addition, the ratio of total baghouse waste to
asbestos mixture consumed (EPA 1986b) was also provided to Versar, Inc. for
each asbestos mixture. Table 39 shows the 1981 8(a) data used to calculate
the waste-to-mixture consumption ratios and the percent of asbestos fibers (a)
in the waste (EPA 1986b).
It should be noted that the Section 8(a) data, the only source of data
available for secondary manufacturers, may not be representative of the
secondary manufacturing plants in the United States. EPA was unable to
determine what percentage of the secondary processors actually submitted
reports in response to the Section 8(a) reporting rule. Therefore, the values
used here may be inaccurate. Furthermore, the reporting rule exempted certain
classes of potential respondents that process asbestos-containing products.
A difficulty in analyzing the values reported in the 8(a) data is that all
secondary processors reported their individual products according to the more
general categories of products listed on the reporting form. Therefore, a
variety of products are reported within each product mixture category. For
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Table 38. Asbestos Emissions from Secondary Manufacturing Sources
00
Total Asbestos
TSCA Content
Identification 1985 Asbestos of Wasted
Asbestos Product/Mixture Number Mixture Consumption* (short tons)
Millboard
Beater-Add Gasketing
High Grade Electrical Paper
Drum Brake Linings (LSM)
Disc Brake Pads (LfiM)
Disc Brake Pads (H)
Brake Blocks
Clutch Facings
Friction Materials
Asbestos Cloth, Thread, Yarn, Roving,
Cord, Rope, Hick, etc.
Sheet Gasketing
Packing
Adhesive* and Sealants
Asbestos-Reinforced Plastics
03
05
06
ia
19
20
21
22
24
26
27
28
30
31
157
4,868
17
1,564,830
1,304,000
800
4,000
87,705
253,138
477
845.971
2,114
25
135
.3 tons
.9 tons
.6 tons
pieces
pieces
pieces
pieces
pieces
pieces
.1 tons
sq yd
Ibs.
.4 gallons
.1 tons
30
437
-
11
2
0
0
0
25
2
2
0
2
4
.0
.0
.2
.29
.0014°
.011
.23
.68
.81
.083
. 15E-4
.07
Baghouse
Efficiency
(e)
99
09
99
99
99
99
99
99
99
99
99
99
99
99
.67
.67
.67
.95
.95
.95
.95
.95
.95
.67
.67
.67
.67
.95
Emission Rate
(g/sec)
2.
4.
1.
3.
2.
1.
3.
3.
2.
2.
7.
2.
5.
66E-3
17E-2
-
6 IE- 4
30E-5
02E-8
57E-7
36E-6
60E-4
55E-4
68E-4
68E-6
05E-8
86E-S
Hours of
Operation
(hr/yr)
8,760'
8,760
-
8,760
8,760
6,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
8,760
Total
Emissions
(kg/yr)
90
1,315
-
5.1
1.0
6E-4
5E-3
0.1
11.4
8
B.4
0.2
6E-4
2
'iCF Market Survey 1986-1987.
This product category has been raclasslfied as non-roofing adhesive*, sealants, and coatings (ICF Market Survey 1986-1987).
°The data to calculate the waste-to-fiber consumption ratio for this product category was not available (missing front the 8(a) data --
see Table 39). The waste-to-fiber consumption ratio calculated for disc brake pads — light and medium vehicles (19) is assumed.
Estimated from 1985 asbestos mixture consumption and 1981 Section 8(a) data (EPA 1986b) on waste-to-consumption ratios and asbestos content (see
Table 39).
-------
Table 39. 1981 Secondary Manufacturer Asbestos Mixture Consumption and Waste Generation"
Asbestos Mixture/
Product (ID*)
Millboard (03)
Beater-Add Gasketlns (OS)
Drum Brake Lining (18)
Disc Brake Pads (LSM) (19)
Disc Brake Fads (H) (20)
Brake Blocks (21)
Clutch Facings (22)
Friction Materials (24)
t
!"* Thread, Yarn, Roving, Cord, Rope,
vo Hick (26)
Sheet Gasketlns (27)
Packing (28)
Adheslves and Sealants* (30)
Asbestos-Reinforced Plenties (31)
End Product Description*5 (ID*)
Other Electrical Products (142)
Sheet Gasketlng (155)
Drum Brakes for Light-Medium
Vehicles (101)
Disc Brake Pads for Light-Medium
Vehicles (102)
N/A
Brake Blocks for Heavy
Equipment (104)
Clutch Facings (105)
Friction Materials (Coomercial
and Industrial) (107)
Brake Blocks for Heavy Equipment
(104)
Sheet Gasketing — Rubber
Encapsulate Compressed (1S6)
Automotive and Friction Components
(113)
Automotive (113)
Asbestos-Reinforced Plastics (203)
1981 Total Asbestos
Mixture Consumption
72 tons
3,941 tons
44,721,663 pieces
22,060,325 pieces
N/A
2,396,352 pieces
3,010,546 pieces
1,878,822 pieces
2,340,000 Ibs
(1,170 tons)
758,584 sq yd
295,320 U>s
1,341,099 gallons
359,156 U»
(179.58 tons)
Total
Quantity of
Baghouse Haste0
(short tons)
31.5
868.7
685.6
180.4
N/A
12.5
35.4
489.4
12.5
6.5
117.2
117.2
28.0
Percent of
Asbestos in
Haste (a)d
(Z)
43.5
40.8
46.7
21. ,5
N/A
52.5
22.5
38.0
52.5
38.8
9.7
9.7
19.3
N/A - Not Available.
'EPA 1986b.
DEPA 1986b (Table 8).
EPA 1986b (Table 17 — Baghouse Fines Dry).
dEPA 1986b (Table 16).
*This product category has bean reclaisified as non-roofing adhe.ives, sealants, and coatings (ICF Market Survey 1986-1987).
-------
example, product mixture number 155 represents "sheet gasketing" products.
All processors of sheet gasketing products provided their information under
this category including processors of beater-add gasketing paper which should
fall under paper products rather than gasketing products. In this case, the
selection of the product mixture to be used in calculating the waste-to-
mixture consumed ratio (Table 39) is based on the product mixture with the
highest consumption level in 1981 (Table 8 of EPA 1986b).
In addition, respondents often reported production using a unit of measure
that differed from the standard unit of measurement for their product. In
some cases, it is not possible to convert the reported value to a consistent
unit.
OAQPS developed model plants for three types of secondary processors of
asbestos products: friction products (i.e., brake rebuilders) , A/C building
products, and A/C or asbestos-silicate boards (OAQPS 1987). No secondary
manufacturers of A/C building products were identified in the ICF Market
Survey (1986-1987). Only the number of baghouses and the exhaust gas flow
rates are available from the model plant. Therefore, other plant parameters
such as stack dimensions, and exhaust gas velocity and temperature were not
provided to Versar, Inc. for input into the ambient exposure model.* There
are no plant parameters available for the other secondary processors which
OAQPS was unable to model.
The approach used to calculate asbestos emissions from secondary sources
is the same as for primary sources. The asbestos emissions are calculated for
each plant based on the emission rate equation presented in Section A.I.
Several secondary processors refused to provide the annual mixture consumption
JU
The default values discussed in Section A.2 can also be applied to
secondary manufacturing sources.
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rate; therefore, asbestos air releases could not be estimated for these
plants. Since the number of control devices or baghouses at most of the
plants is not available, the emission rates provided to Versar, Inc. for
ambient exposure modeling represent the total emission of asbestos fibers per
plant rather than per control device. Only aggregate emission estimates are
reported in Table 38.
Secondary manufacturing sources for which we are unable to estimate air
releases are the specialty products such as specialty paper, insulation
materials (i.e., missile liner), and the miscellaneous products (e.g., cooling
tower fill, ceramic arc chutes, and fuel cells). A/C pipe and asbestos
coatings do not require secondary processing. Asbestos diaphragms are used
within the primary manufacturing plants and, therefore, do not undergo
secondary processing. In addition, there are currently no secondary
processors of A/C sheet in the U.S. V/A floor tile, commercial paper,
rollboard, flooring felt, and corrugated paper products are no longer produced
or sold in the U.S. (refer to Appendix A for a discussion of emission factors
for these products).
C. Mining and Trade Use Emissions
This section discusses the methodology used to calculate asbestos air
emissions and the resulting emission estimates for three sources: mining
activities, automotive brake servicing, and construction related operations.
A brief introduction to each asbestos-generating source is presented, followed
by the methodology and the emission estimates.
* ICF (IGF Market Survey 1986-1987) was able to estimate the annual
consumption rates for the primary processors that refused to respond to the
market survey; however, ICF is unable at this time to estimate the mixture
consumption rates for those secondary refusal plants due to limited data
availability on the secondary processors.
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Asbestos mines operate somewhere from 7 to 10 months per year, mainly
during the dry months. The potential emission points during mining activities
include drilling, blasting, loading ore into trucks, and hauling and dumping
ore into stockpiles at the mills. Blasting and drilling processes are the
main sources of emission; these processing steps are performed in open pit
mine areas. There are three facilities currently mining asbestos; they are
the Vermont Asbestos Group, Calaveras Asbestos Ltd., and KCAC Incorporated.
Automotive servicing includes repair of automotive brakes, clutches,
automatic transmission components, and other friction materials. However,
exposure data are only available for automotive brakes which are the
automotive products of greatest concern with respect to asbestos exposure;
therefore, only emissions from automotive brake servicing are estimated.
Brake servicing may be performed at service stations, independent repair
shops, new car and truck dealer shops, and self-serviced fleet shops. There
are approximately 329,000 facilities in the U.S. where brake repair is
performed (Hunter Publishing Co. 1985). Location and facility-specific
information on automotive repair shops are not presented in this analysis due
to the large number of facilities involved.
The asbestos-related activities performed in the construction trade
include installation and removal of asbestos material. This analysis focuses
only on those construction materials that were still being produced or
imported in 1986 which are limited to roofing felt, roof coatings,
asbestos-cement pipe, and asbestos-cement shingles and sheet (flat and
corrugated). These asbestos construction materials are used for exterior
applications such as roofing, sewer pipe, and exterior walls.
The construction industry is different than general industry in that the
worksites are temporary in nature and seasonal. The site conditions, size and
scope of tasks, methods of operation and environmental conditions are quite
- -182 -
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varied (CONSAD 1984) . Some general characteristics of the construction
industry are:
• Construction work is performed at temporary locations that
vary in size, physical boundaries, and working surface;
• Construction work is usually performed in open air, subject
to weather variability;
• Construction work varies as the project progresses from
initiation to completion, demanding a variety of materials,
equipment and skills; and
• Employment is transient in construction, permitting
tradesmen and laborers to work for several different
contractors at several different sites per year (CONSAD
1984).
Due to highly variable nature of construction jobs, detailed information or
site-specific data on construction activities are not available.
Unlike milling and manufacturing sources, engineering controls for
asbestos air releases are typically not feasible at mining, brake servicing,
or construction sites. Pollution control equipment such as baghouses are not
applicable, thus there are no stacks. The points of emissions cannot be well
defined due to the nature and large number of the work settings. For indoor
jobs, for example, asbestos is emitted through a number of openings such as
windows, doors, and cracks. For outdoor jobs, airborne asbestos can be
dispersed in any or all directions, depending on the wind vectors. In other
words, the release configuration from these sources is unconfined with
multiple exits. All of these factors contribute to the difficulty of making
an accurate assessment of asbestos air emissions from these sources. As a
result, generalized assumptions must be made to estimate asbestos emissions.
With respect to mining emissions, an attempt was made to estimate
emissions using the available data on particulate emissions from general
mining operations (non-asbestos) since asbestos emission menasurements are not
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available. A literature search* on the subject resulted in many mining
related documents. The majority of these reports vere emission studies on
coal mines. Other non-coal surface mining reports included open pit and strip
mining of clays, cement, sand and gravel, stone, iron, gypsum, and phosphate
rock. One study which compiled particulate emissions from open sources
estimated a rough emission factor of 2 Ibs/ton of production for all surface
mining (Evans and Cooper 1980). Another study (Axetell and Cowherd 1984)
developed fugitive dust emission factors for individual coal mining operations
in the form of equations with several correction factors to account for site-
specific conditions. The resulting emission factors for significant sources
of particulate emissions at surface coal mines which were developed from
extensive sampling at three different Western mines are: (1) drills --
overburden (1.3 Ib/hole), (2) blasting (35.4 Ib/blast), (3) loading -- coal
(0.037 Ib/ton), (4) dozers -- coal (46.0 Ib/hr), (5) dozers -- overburden (3.7
Ib/hr), (6) dragline (0.059 lb/yd3), (7) scrapers (13.2 lb/VHT**). (8) graders
(5.7 Ib/VMT), (9) light and medium duty vehicles (2.9 Ib/VMT), and (10) haul
trucks (17.4 Ib/VMT) (Axetell and Cowherd 1984). There are diverse values for
emission factors for surface mining in the published literature (Axetell and
Cowherd 1984, EPA 1977) due to problems encountered in sampling mining
sources. Each mine is unique in its emission characteristics, and the
selection of mines may have influence final emissions factors.
Use of emission factors from surface coal mining sources (or non-coal
mining sources) to estimate emissions from asbestos mines would result in
unreliable emission estimates with a high margin of error. Asbestos dust is
* A literature search was performed on-line using APTIC, Pollution
Abstracts, NTIS, and GPO. Key words used vere mining emission
measurements/estimates, surface mining, and asbestos/non-asbestos.
** VMT - vehicle miles traveled.
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not similar to coal dust in particle size, geometry, density, etc. (Asbestos
is unique for its crystal structure/fibrous form.) Coal dust particles are
quite different from asbestos "dust particles". Generally, large dust
particles tend to settle out near the source whereas fine dust particles emit
and disperse over much greater distances. Depending on the sample location,
this factor affects the sampling results and, thus, the emission factors.
Emission factors are extremely source and site-specific (Yocom 1976). The
type of pollutant and its behavior in the environment are important factors.
There is no basis for assuming that the published emission factors for coal
mining would be appropriate for asbestos mining sources.
Recognizing the difficulties and uncertainties associated with estimating
asbestos mining emissions, the "bubble" approach used to estimate air releases
in this study (described below) is highly generalized. One weakness of this
approach is that it does not account for fugitive emissions which occur 24
hrs/day (this weakness applies to both mining and construction sources). To
date, efforts have been directed at asbestos emissions from well defined
sources and little attention has been given to fugitive emissions from
asbestos mines (Roy 1987). This is due to the fact that asbestos mines are
further removed from population centers and air emissions are suspected to be
rather low (Roy 1987). Since there are only 3 asbestos mines in the U.S.,
actual air sampling at these mines should be considered if better estimates
are required.
1. Methodology
The methodology to calculate the asbestos air release rate from
mining, brake servicing, and installation and removal work in the construction
sector is based on a bubble/air exchange rate approach. The rationalization
for using this method assumes that a worker's activity at a worksite causes
the release of asbestos fibers to the air; these airborne asbestos fibers are
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assumed to accumulate in a specified volume of air over a period of time.
This volume of asbestos-contaminated air is replaced periodically (as defined
by the air infiltration rate) by asbestos-free air, thereby transferring
airborne asbestos fibers downwind. This simplified approach is used due to
the lack of actual emission measurement data. The emission rates are
calculated based on the following equation:
Asbestos Emission - (c) (v) (ac) ( )
Rate (g/sec) 3600 sec
where, c - typical asbestos airborne concentration (g/ft^);
o
v - volume of the work area (ft0); and
ac - number of air changes per hour (air infiltration rate).
As shown in the emission rate equation, there are three parameters that
can influence the downwind asbestos concentration levels. The first
parameter, asbestos airborne concentration (c), is derived from the
occupational exposure analysis (refer to Chapter II). The projected (i.e.,
based on the new 0.2 f/cc PEL) exposure level (geometric or arithmetic mean)
is assumed for c, which is defined as the typical work area concentration.
The exposure concentration is often expressed as fibers per cubic centimeter
(f/cc); therefore, a conversion factor of 30 fibers/ng is applied to convert
fiber counts to fiber mass.
The second parameter in the emission rate equation, the volume of the worl
area (v), is a function of the types of activities performed. The types of
activities performed determine the work setting (i.e., indoors versus
outdoors) from which asbestos is released. For indoor work such as brake
servicing, the assumed value for v is based on knowledge of the work setting
related to the activity under study. For example, brake servicing is
For additional infc "mation on the fiber-to-mass conversion factor, see
Section B of Chapter I.
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typically performed inside a service garage; therefore, a "typical" garage
size is chosen as the work volume. The work area volume for indoor activities
is assumed to be the volume of the structure in which the work is performed.
For work performed outside, the selection of a work area or "bubble"
volume is less clearly defined. Since there are really no physical boundaries
to the work area for outdoor activities (e.g., installation of roofing felt),
this is merely an arbitrary assumption thought to reasonably represent a work
space. The "work area air volume" can be thought of as an imaginary room or a
cubic air bubble surrounding a worker where airborne asbestos fibers are being
accumulated over a period of time. A 216 ft^ (or a 6-foot cubic) air volume
or "bubble" is assumed for all outdoor work to represent the work area. The
selection of this 216 ft^ work area is based on the assumption that the area
should be relatively small and close to the worker's breathing zone.
The third parameter in the emission rate equation is the air change rate
(ac). The air change rate or air infiltration rate is dependent upon the
size, shape, and construction of the structure, and upon the pressure
difference between the inside and outside environments. Infiltration is air
leakage through cracks and interstices, around windows and doors, and through
floors and walls into a building (ASHRAE Handbook 1977). One source estimates
the leakage rate for houses ranging from 0.5 to 1.5 air changes per hour in
the winter (ASHRAE Handbook 1977). Another source estimates 0.3 to 1.8 air
changes per hour as a typical leakage rate for buildings in the summer and 0.5
to 3.0 air changes per hour in the winter (Perry 1973). The range of
estimates is due to the variation in the number of windows and doors in the
buildings studied. For indoor activities, one air change per hour is assumed
to be typical (ASHRAE Handbook 1977).
For outdoor activities, the air change rate varies highly, and it is
virtually impossible to measure. The only basis to estimate the outdoor air
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change rate is the wind flow. The wind flow is used as an indicator of the
dilution rate of asbestos contaminants at the source as they are emitted. For
this analysis, 4,000 air changes per hour (approximately 66 air changes per
minute) is assumed. This is a rough estimate based on a long-term average
horizontal wind flow of about 2 meters/sec and a 216 ft-* work area. The
assumption for the air change rate is directly related to the assumption for
the work area air volume. If a larger work air volume is selected, a lower
air change rate would be used.
It is important to emphasize that there are many uncertainties in the
estimation of air releases from mining, brake servicing, and construction
activities. Many factors can affect the release of asbestos. Simple
assumptions are made when no data are available and there is a lot of room for
subjective judgment. The way in which the assumptions are utilized to reach
quantitative estimates makes the numerical values appear more precise than
they actually are. The asbestos emission rates may vary considerably between
worksites and processes (also during the course of a particular process); the
approach used in this analysis is a simplified one due to.the lack of actual
air emission data.
2. Emission Estimates
Emissions are estimated below for mining, brake repair, and
construction activities using both the geometric and arithmetic mean workplace
asbestos concentrations. As described in Chapter I (Section A.2), the
arithmetic mean of the raw exposure data is used to estimate health benefits
because it represents total exposure when multiplied by the exposed
population. This is true for both occupational exposure estimates and ambient
exposure estimates, which are based on the emissions estimates presented in
this section. Therefore, the emissions estimates for mining, brake repair,
- 188 -
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and construction calculated using the arithmetic mean exposure are used to
estimate ambient exposures.
a. Mining
Asbestos-air emissions from mining sources are estimated for the
three mining facilities presently in operation. The mining methods employed
are the conventional open-pit stripping method (KCAC Incorporated) and the
open-pit bench method (Calaveras Asbestos, Ltd. and Vermont Asbestos Group).
Open-pit stripping is a surface mining method where the asbestos-containing
ore lies near the surface; therefore, power shovels and bulldozers are used to
remove the ore such that blasting and drilling are not necessary. In the
open-pit bench method, however, blasting and drilling are required because the
ore body goes deeper and is surrounded by hard rocks. As mentioned earlier,
blasting and drilling processes are the main sources of dust releases;
however, these operations are performed intermittently as needed.
The locations of the asbestos mines are shown in Table 40, along with the
emission estimates. The emissions are calculated based on the emission rate
equation presented in Section C.I above. The typical asbestos concentration
during mining operations (both geometric mean and arithmetic mean) is obtained
from the occupational exposure analysis (see Chapter II, Section A). Because
mining operations are performed outdoors, an air bubble volume of 216 ft^ is
assumed with 4,000 air changes per hour. The average work day for mine
workers is 8 hours; therefore, the 8-hour TWA exposure concentration is
applied. The duration of asbestos releases is also 8 hours per day, 4 or 5
days per week, for approximately 7 to 10 months per year (refer to Table 40
for the appropriate duration for each mining facility).
The asbestos emission rates are calculated per mine worker then multiplied
by the number of mine workers to obtained the total emissions per mining site.
As shown in Table 40, the asbestos emission rates calculated for mining
- 189 -
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Table 40. Asbestos Emissions from Mining Sources
Mine and Location
Asbestos
Concentration (c)
8-Hour TWA
(f/cc)'
Work Area
Geometric Arithmetic Volume (v) Per Hour
Mean Mean (ft3) (ac)
Asbestos Emission Rate
Number of per Worker
Air (it/sec)
Changes
Total Asbestos
Bnlaslon Rate Per S
(K/sec)
Using Using Number of Ueing Using
Geometric Arithmetic Workers Geometric Arithmetic
Mean Mean Per Site" Mean Mean
Duration of
Emissions*
Calavaras Asbestos, Ltd. 0.06 0.06
Copperopolls Mine
Calavera's County, CA 95228
KCAC Inc. 0.53 0.57
Joe 5 Pit
San Ban!to County, CA 93930
Vermont Asbestos Group, Inc. 0.42 0.54
Lowell Mine
Orleans County, VT 05661
216 4,000 1.36xlO~5 1.36xlO~5 25
216 4,000 1.20xlO~* 1.29xlO~*
216 4,000 9.51xlO~5 1.22xlO~* 16
3.40xlO~* 3.40xlO~* 8 hr/d, 5d/wk
(10 mos/yr)
3.60x10** 3.87xlO~* 8 hr/d, 4d/wk
(7 mos/yr)
1.52xlo"3 1.96xlo"3 8 hr/d, 186 d/yr
"Refer to Chapter II, Section A. The weighted average exposure without usage of respirators is the appropriate exposure to use because we are Interested in
the concentration of asbestos fibers in the work area.
-------
-4 -3
sources range from 3.40 x 10 g/sec to 1.52 x 10 g/sec. It should be noted
that the rate of asbestos emission at any time may be higher than the
estimated value because the short-term peak exposure concentration is often
higher than the 8-hour TWA concentration. Emissions from mining sources are
assumed to be area source emissions rather than point source emissions. One
mine (Vermont Asbestos Group) estimated an area of 2300+ acres as the total
area of the facility including the area of asbestos deposits, with 10 acres as
the portion where asbestos operations are performed (ICF Exposure Survey
1986-1987). Since there are no stacks, the release velocity depends on the
magnitude of the wind flow which is a function of the meteorological
conditions at a particular time. Ambient air temperature is assumed at the
release point. Fiber size distribution data are not available.
b. Brake Repair
Asbestos air emissions are estimated for four types of brake
servicing jobs: drum brake shoes for cars (and light trucks), drum brake
shoes/brake blocks for trucks, disc brake pads for cars (and light trucks),
and disc brake pads for trucks. Based on a 1984 survey of a cross-section of
automobile and truck servicing facilities performed by the Hunter Publishing
Co. (1985), the majority of brake repair work is done at independent repair
shops (45.6 percent) and service stations (35 percent). Table 41 shows the
distribution of brake repair work by types of facilities. The installation of
disc brake pads and drum brake shoes on trucks represents a small fraction of
the total brake repair work. Approximately 60 percent of the brake servicing
shops are located in cities with population over 25,000 people and 40 percent
with population under 25,000 (Hunter Publishing Co. 1985). Since this is a
service industry, it is reasonable to assume that brake servicing shops are
located mainly in populated areas.
- 191 -
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Table 41. Distribution of Brake Repair Work by Types of Facilities
fO
Total Number
Type of Facility of Facilities
Service Stations 115,000
Independent Repair 150,000
Shops
New Car end Truck 25,000
Dealer Shops
Self -Serviced Fleet 39,000
Shop
Total 329.000
Number of
Drum Brake Shoes
(Axle Sets) Installed
As Replacements
on Cars (1989)"
9,774,140
11,726,960
3,157,800
400,990
25,061,890
Number of
Drum Brake Shoes
(Axle Sets) Installed
As Replacements
on Trucks (1985)'
123,970
238,230
74,260
134,820
571,280
Number of
Disc Brake Pads
(Axle Sets) Installed
As Replacements
on Cars (1989)'
6,854,070
8,377,190
2,647,340
253,850
18,132,450
Number of
Disc Brake Pads
(Axle Sets) Installed
As Replacements
on Trucks (1985)'
5,290
8,940
3,330
2,040
19,600
'These value* represent the number of asbestos lining* for drum brake shoe* and disc brake pad*. The total number of asbestos
linings for each category is based on Tzanetos et al. 1987 and ICF Market Survey (1986-1987) (see Chapter II, Section D). The
distribution of the total number of breke jobs by type of facility ie based on the results of the 1964 survey performed by Hunter
Publishing (1985).
Source: Hunter Publishing Co. 1985 and 1986, Tzanetos et al. 1987, ICF Market Survey 1986-1987, ICF 1987.
-------
Using the emission rate equation presented in Section C.I above, asbestos
air emissions from brake servicing shops are calculated. The geometric mean,
8-hour TWA area concentration found at brake repair shops is 0.03 f/cc; the
arithmetic mean, 8-hour TWA area concentration is 0.04 f/cc (see Chapter II,
Section D). The area concentration is used to calculate asbestos emissions,
rather than the personal breathing zone concentration (0.09 f/cc geometric
mean; 0.15 f/cc arithmetic mean). Since airborne fibers are continuously
dispersed into a confined work area air volume, it is more appropriate to use
the area concentration. Over a period of time, the area concentration can be
thought of as the equilibrium concentration of the personal concentrations.
The personal exposure concentration varies during brake servicing but the
8-hour TWA area concentration is assumed to be constant throughout the day.
Whether it is a car servicing job or a truck servicing job, the typical
asbestos concentration level is assumed to be the same because of the
similarity of the brake servicing procedures (see Chapter II, Section D). The
difference between car versus truck servicing estimates then is in the
assumptions of the shop areas. Truck servicing facilities require more shop
space than car servicing facilities. A 3-bay garage is assumed to be typical
for brake repair shops/service stations.* The shop area is estimated to be
about 900 square feet (each bay is 15 ft x 20 ft) with a ceiling height of 10
ft for car servicing shops. Thus, the total work area air volume is 9,000
ft3. Truck servicing shops are also assumed to have 3 bays, each with a 25 ft
x 30 ft area and a 20 ft ceiling height, which yields a total work area air
volume of 45,000 ft3. Because of the variation in shop sizes, one air change
* Since over 80 percent of brake repair work is performed at service
stations and independent repair shops, the assumption for the work area
is based on what is typical for these facilities.
- 193 -
-------
per hour is assumed for car servicing shops whereas 1.5 air changes per hour
is assumed for truck servicing shops.
The average time for a brake job ranges from 1 to 3 hours (Chapter II,
Section D) -(the actual time that a mechanic would spend on brake jobs in a day
is not known). It is assumed that mechanics (full-time equivalents) perform
multiple brake jobs a day for a full 8-hour day. The duration of release is,
therefore, also 8 hours per day.
Table 42 shows the emission estimates for brake servicing. For both the
installation of drum brake shoes and disc brake pads on cars, the estimated
asbestos emission rates using geometric mean and arithmetic mean area
-8 -8
concentrations are 7.08 x 10" g/sec and 9.44 x 10" , respectively. For both
drum brake shoe and disc brake pad installation on trucks, the estimated
emission rates using geometric mean and arithmetic mean area concentrations
are 5.31 x 10" g/sec and 7.08 x 10" , respectively.
Since the data from the Hunter Publishing Co. (1985) gives a breakdown of
the number of brake jobs performed in each regional area in 1984, it may be
more appropriate to model asbestos emissions for each regional area (since
facility-specific information is not available). Tables 43, 44, 45, and 46
present the number of brake jobs performed in each region, and the amount of
asbestos released per region for drum brake shoes on cars, drum brake shoes on
trucks, disc brake pads on cars, and disc brake pads on trucks, respectively.
Based on the typical time required per brake job (discussed in Chapter II,
Section D), the total time spent on brake repair work in each region is
calculated. This number is then applied to the emission rate calculated
earlier (Table 42) to obtain grams of asbestos released for each region per
year.
From Tables 43, 44, 45, and 46, it can be seen that the East North Central
region has the highest asbestos release rate for brake servicing work on cars,
- 194 -
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Table 42. Asbestos Emissions from Brake Repair
vo
Ul
Asbestos Area
Concentration (c) Asbestos Emission Rate
8-Hour TWA Number of U/sec)
(f/cc)a Work Area Air Changes Using Using
Geometric
Job Description Mean
Drum Brake Shoe Installation on Cars 0.03
Drum Brake Shoe Installation on Trucks 0.03
Disc Brake Pad Installation on Cars 0.03
Disc Brake Pad Installation on Trucks 0.03
Arithmetic Volume (v) Per Hour Geometric Arithmetic Effective Duration
Mean (ft ) (ac) Mean Mean of ' Exposure
0.04 9,000 1 7.08xlO~8 9.44xlo"8 8 hr/d, 5 d/wk, 250 d/yr
0.04 45,000 1.5 5.31xlo"? 7.08xlo"7 8 hr/d, 5 d/wk, 250 d/yr
0.04 9.000 1 7.08xlo"8 9.44xlO~8 8 hr/d, 5 d/wk, 250 d/yr
0.04 45,000 1.5 5.31xlo"7 7.08xlo"7 8 hr/d, 5 d/wk, 250 d/yr
•Refer to Chapter II, Section D (Table 27).
-------
Table 43. Asbestos Emission Estimates In g/yr for Each Region --
Installation of Drum Brake Shoes on Cars
vO
Region
New England
Middle Atlantic
East North Central
West North Central
South Atlantic
East South Central
West South Centra
Mountain
Pacific
Total
Number of Replacement
Asbestos Drum
Brake Shoes Installed
Per Year (1989)*
1.723,530
3,773,890
4,487,270
2,770,830
3,688,080
949,480
12,141,240
1,518,670
4, 004,, 900
25,061,890
Number of
Establishments
Per Region
22,650
49,570
58,910
36,370
48,420
12,460
28,110
19,940
52,570
329,000
Total Servicing
Hours Far Year
Per Region0
(hours)
2,588,300
5,663,840
6,730,900
4,156,250
5,532,120
1,424,220
3,211,860
2,278,000
«. 007. 350
37,592,840
Emission Estimate Per Region
(it/year)
Using
Geometric Mean
659.7
1,443.6
1,715.6
1,059.3
1,410.0
363.0
818.6
580.6
1.531.2
9,581.6
Using
Arithmetic Mean
879.6
1,924.8
2,287.4
1,412.5
1,880.0
484.0
1,091.5
774.2
2.041.5
12.775.5
*The total number of replacement drun brake shoes installed on cars in 1989 la based on Tzanetos et el. (1987) (see
Chapter II, Section 0). The distribution of the total number of drum brake jobs on cars by region is based on the results
of the 1984 survey performed by Hunter Publishing (1985).
This is an estimate. The average number of brake jobs per establishment per year is calculated using the data presented
in Table 41 (25,061,890 total Jobs/329,000 facilities equals approximately 76.176 brake jobs par establishment); this
number is divided by the number of brakes installed per year par region to obtain the number of establishments for each
region. Consequently,'all brake repair facilities (e.g., service station or self-serviced fleet shops) are assumed to
perform the same number of brake jobs a year.
°The total hours spent on brake repair work is calculated based on an estimated 1.5 hours per drum brake Job (see
Chapter II, Section D).
-------
Table 44. Asbestos Emission Estimates In g/yr for Each Region —
Installation of Drum Brake Shoes on Trucks
vo
Region
New England
Middle Atlantic
East North Central
West North Central
South Atlantic
East South Central
West South Central
Mountain
Pacific
Total
Number of
Asbestos Drum
Brake Shoes Installed
Per Year (1985)'
31 , B20
77,990
90,590
68.910
81,970
21,570
55,500
51,530
91.400
571,280
Number of
Establishments
Per Region
18,330
44 , 920
52,170
39,680
47,200
12,420
31,960
29,680
52.640
329,000
Total Servicing
Hours Per Year
Per Region0
(hours)
79,550
194,960
226,470
172,280
204,920
53,930
138,750
128,820
228.500
1,428,200
Bnisslon Estimate Per Region
(x/year)
Using
Geometric Mean
152.1
372.7
432.9
329.3
391.7
103.1
265.2
246.3
436,8
2,730.1
Using
Arithmetic Mean
202.8
497.0
577.2
439.1
522.3
137.5
353.6
328.3
582.4
3,640.2
"The total number of drum brake shoes installed on trucks in 1965 it based on the ICF Market Survey 1986-1987) (see
Chapter II, Section D). The distribution of the total number of drum brake Jobs on trucks by region is baaed on the
results of the 1984 survey performed by Hunter Publishing (1985).
This is an estimate. The number of brake Jobs per establishment per year la calculated using the data presented In
Table 41 (571,280 total asbestos jobs/329,000 facilities equals approximately 1.736 brake Joba per eatabllahment); this
number is divided by the number of brakes Installed per year per region to obtain the number of establishments for each
region. Consequently, ell brake repair facilitiea (e.g., service stations or self-serviced fleet shops) are assumed to
perform the same number of brake Joba a year.
cThe total hours spent on brake repair work la calculated based on an estimated 2.5 hourr per drum brake Job (see
Chapter II, Section D).
-------
Table 45. Asbestos Emission Estimates in s/yr for Each Region —
Installation of Disc Brake Pads on Cars
vo
00
Region
Hew England
Middle Atlantic
East North Central
West North Central
South Atlantic
East South Central
West South Central
Mountain
Pacific
Total
Number of Replacement
Asbestos Disc
Brake Shoes Installed
Per Year (1989)*
1,268,580
2,700,780
3,244,870
2,002,890
2,653,960
650,480
1,629,380
1,113,620
2. 867. 690
18,132,450
Nunber of
Establishments
Per Region
23,020
49,000
58,880
36,340
48,150
11,800
29,560
20,210
52.040
329,000
Total Servicing
Hours Per Year
Per Region0
(hours)
1,385,440
2,970,860
3,569,360
2,203,180
2,919,350
715,530
1,792,320
1,224,980
3.154,680
19,945,700
Emission Estimate Per Region
(«/vear)
Using
Geometric Mean
355.7
757.2
909.8
561.5
744.1
182.4
456.8
312.2
804,1
5,083.8
Using
Arithmetic Mean
474.2
1,009.6
1,213.0
7*8.7
992.1
243.2
609.1
416.3
1.072.1
6,778.3
*The total number of replacement disc brake pads installed on cars In 1989 ia based on Tzanetos et al. (1987) (see
Chapter II, Section D). The distribution of the total number of disc brake Jobs on cars by region is based on the
results of the 1984 survey performed by Hunter Publishing (1985).
This is an estimate. The number of brake jobs per establishment per year is calculated using the data presented in
Table 41 (16,132,450 total asbestos Jobs/329,000 facilities equals approximately 55.114 brake Jobs per establishment);
this number Is divided by the number of brakes installed per year per region to obtain the number of establishments for
each region. Consequently, all brake repair facilities (e.g., service stations or self-serviced fleet shops) are assumed
to perform the same number of brake Jobs a year.
cThe total hours spent on brake repair work is calculated based on an estimated 1.1 hours per disc brake Job (see
Chapter II, Section D).
-------
Table 46. Asbestos Emission Estimates in g/yr for Each Region --
Installation of Disc Brake Pads on Trucks
Region
New England
Middle Atlantic
East North Central
West North Central
South Atlantic
East South Central
West South Central
Mountain
Pacific
Total
Number of
Asbestos Disc
Brake Shoes Installed
Per Year (1985 )a
1,360
2,660
3,170
2,340
2,410
730
2,280
1,680
2.970
19,600
Number of
Establishments
Per Region*1
22 , 830
44,650
53.210
39,280
40,450
12,250
38,270
28,200
49.860
329,000
Total Servicing
Hours Per Year
Per Region0
(hours)
3,400
6,650
7,930
5.850
6,020
1,830
5,700
4,200
7.420
49,000
Emission Estimate Per Region
(K/year)
Using
Geometric Mean
6.5
12.7
15.2
11.2
11.5
3.5
10.9
8.0
1
-------
whereas the Pacific and East North Central regions have the highest annual
asbestos release rate for brake servicing work on trucks.
Data on the fiber size distributions at brake repair facilities is
limited. -Only one industrial hygiene survey (NIOSH 1982b) reported fiber si;
distributions from vehicle brake servicing operations. The fiber size
distribution performed for all airborne sample fibers, observed by
transmission electron microscopy (TEM), showed a geometric mean length of
1.66 urn. For airborne sample fibers identified as chrysotile, a geometric
mean length and diameter of 1.7 urn and 0.15 urn, respectively, were found. TV
TEH analysis also showed that 80 percent of the total fiber population was
less than 5 urn in length and that 30 percent of the fibers were chrysotile, i
percent forsterite, and 50 percent unknown.
There are no stacks at brake repair shops. Asbestos may be released
through a number of openings, depending on the worksites. The multi-release
points and velocities are not known. Exhaust temperature is assumed to be
ambient air temperature.
c. Construction
Asbestos air emissions for each construction activity are
estimated. Two types of activities are analyzed for each product category:
installation and removal. Installation operations are analyzed for A/C pipe,
A/C flat sheet, A/C corrugated sheet, A/C shingle, and built-up roofing;
removal operations are analyzed for A/C flat sheet, A/C corrugated sheet, A/C
shingle, and built-up roofing (exposure estimates for A/C pipe repair or
removal are not available). As discussed earlier, all of the construction
related activities are exterior applications (i.e., outdoor activities); thus
a 6-foot cubic air volume (v) (i.e., 216 ft^ air bubble) is assumed to
represent the work area, with an air change rate (ac) of 4,000 per hour. The
geometric and arithmetic mean short-term TWA exposure concentrations (c) (as
- 200 -
-------
derived in Chapter II, Section E) are also applied. These three variables are
applied to the emission rate equation presented in Section C.I to obtain the
asbestos emissions for construction. The emission rate calculated for each
activity is one that is generated as the result of a single worker's activity
(e.g., cutting or drilling) at a site. To obtain the total annual emissions
for any construction activity, the emission rate is multiplied by the total
hours spent on construction per year. Since the actual time required per job
and the number of workers per job are not known, the total hours spent on
construction activities are taken as the product of the number of full-time
equivalent workers and a full working year (8 hours a day for a total of 250
days per year). Table 47 shows the estimated asbestos emission rates for
construction activities.
No other information concerning the emission sources are available. A/C
sheets and shingles, and built-up roofing materials are generally applied to
(or removed at) residential and commercial installations; therefore, the
locations where these activities take place are mostly in surburban areas.
A/C pipe installation and removal operations are likely to be in both
surburban and rural areas.
Based on location information provided in the NIOSH, industry, and
academic studies used to develop the geometric mean exposures, several job
sites where asbestos construction work has been undertaken include:
• A/C Pipe -- Alameda, CA;
• A/C Sheet -- Denver, CO and Steamboat Springs, CO;
• A/C Shingle -- Waycross, GA and Rockford, IL;
• Build-up Roofing -- New Orleans, LA; Hobart, IN; Racine,
WI; Indianapolis, IN; Allentown, PA; Gary, IN; Anderson,
IN; and Chesterfield, IN.
- 201 -
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Table 47. Asbestos Emissions from Construction Activities
NJ
O
10
Short-Term TWA
Asbestos
Concentration (c)
(f/cc)a
Construction Activity
A/P Pipe Installation
A/C Flat Sheet Installation
A/C Flat Sheet Removal
A/C Corrugated Sheet
Installation
A/C Corrugated Sheet Removal
A/C Shingle Installation
A/C Shingle Removal
Built-Up Roofing Installation
Built-Up Roofing Removal
Geometric
Mean
0.080
0.173
0.800
0.173
0.800
0.046
0.084
0.128
0.072
Arithmetic
Mean
0.114
0.278
0.800
0.278
0.600
0.050
0.094
0.169
0.114
Work Area
Volume (v)
(ft3)
216
216
216
216
216
216
216
216
216
Number of
Air Changes
Per Hour
(ac)
4,000
4,000
4,000
4,000
4,000
4,000
4,000
4,000
4,000
Asbestos Emission Rate
(K/»»C)
Using
Geometric
Mean
i.aixio'5
3.92xlO~3
1.81x10'*
3.92xlO~5
l.Blxlo"*
1.04xlO~S
1.90xlO~5
2.90xlO~5
1.63xlO"S
Using
Arithmetic
Mean
2.58xlO~5
6.30xlo"3
1.81xlO~*
6.30xlo"5
1.81xlO~*
1.13xlo"5
2.13X10*5
3.83xlO*5
2.58xlO~5
Total Construction
Hours ,Pec gear
(hours )b
1,842,000
32,000
40,000
14,000
18,000
472,000
328,000
792,000
526,000
Total Asbestos Emissions
(k*/veer)c
Using >
Geometric
Mean
120.0
4.5
26.1
2.0
11.7
17.7
22.4
82.7
30.9
Using
Arithmetic
Mean
171.1
7.3
26.1
3.2
11.7
19.2
25.1
109.2
48.9
'Projected under the new 0.2 f/ce PEL. Short-term exposures are used to correspond with the full-time equivalent worker population used to calculate
total emissions. (See Chapter II, Section E.)
Tlefer to Chapter II, Section E. The total construction hours per year is the product of the number of full-time equivalent workers and the length of a
full-working year (2,000 hours/year).
°The total emissions would be distributed throughout the U.S.
-------
Asbestos construction work is by no means limited to these locations, but
these locations can be used to model likely ambient exposures and exposed
populations.
D. Emissions from Asbestos-Containing Waste Piles
Asbestos-containing wastes are generated during a variety of processes,
including the mining and milling of asbestos ore, the manufacture and
fabrication of asbestos products, and the installation/demolition/renovation
of asbestos building materials. The handling, transport, and disposal of
these wastes are regulated by the U.S. Environmental Protection Agency (EPA)
and the Occupational Safety and Health Administration (GSHA). These
regulations are found in the Code of Federal Regulations (40 CFR Part 61,
Subpart M and 29 CFR Parts 1910 and 1926). OSHA's requirements governing
asbestos-containing wastes are designed to protect employees from exposure to
asbestos fibers that are released at the worksite. EPA also sets forth
regulations governing the handling of asbestos wastes onsite. In general,
EPA's regulations are found to be very similar to OSHA's. The disposal of
asbestos wastes off-site is regulated by EPA. A discussion of the types of
asbestos-containing wastes that are generated and the regulations governing
their handling is presented below, followed by estimates of emissions from
mining/milling waste piles.
1. Regulations Affecting Management of Asbestos Wastes
a. Mining and Milling Wastes
Asbestos is 'manufactured1 by mining the ore deposit and separating
the fibers from the non-asbestos rock. The process of separating the fibers
from the mined ore, and grading and packaging these fibers, is called milling.
The following three types of wastes are generated from the mining and milling
process:
- 203 -
-------
• Mine waste;
• Tailings; and
• Wastes from air cleaning devices.
Mine wastes are defined as overburden, or waste rock, having insufficient
asbestos for additional processing (i.e., milling). Approximately 4 million
metric tons of mine waste were generated in 1982 (EPA 1985b). This waste is
typically piled in an area adjacent to the mine. EPA does not regulate the
handling of these wastes since the asbestos content of mine waste is extremel;
low (approximately 0.1 percent). Mills also generate waste rock, called
tailings, that contain residual amounts of asbestos. The asbestos content of
tailings is higher than that of mine waste (approximately 1.4 percent). It
has been estimated that between 1 and 2 million metric tons of tailings were
generated in 1982 (EPA 198Sb, EPA 1986d). Wastes from air cleaning devices
generated approximately 30,000 tons of wastes in 1981; the average asbestos
content of these wastes was found to be 5 percent (EPA 1986b). According to
one source, a ratio of 16.5 tons of asbestos waste is generated during millinj
operations for every one ton of asbestos produced (EPA 1986d). Production
figures submitted to EPA in 1981 place this ratio at 15 tons of waste per ton
of asbestos produced (EPA 1986b).
Tailings are disposed by loading on a conveyer belt and dumping on a wast*
pile, usually located within 5 miles of the mill. Under 40 CFR Part 61,
Subpart M, EPA requires that during the collection, processing, packaging,
transport or disposal of asbestos-containing waste, there either be no visibl'
emissions to the outsite air or a wetting agent or air cleaning device be use'
to control the dust. Emission control during transport and dumping is usuall}
achieved by enclosed conveyors, negative air hoods, or the use of a wetting
agent (i.e., water) introduced via a mixing screw conveyor. An alternative
disposal method nay be used if prior approval by the Administrator has been
received.
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Waste piles are regulated under 40 CFR §61.156. A waste pile is an
acceptable site for the disposal of asbestos wastes if either there are no
visible emissions to the outside air or the waste is covered within 24 hours
of deposit. The minimum required cover is 6 inches of non-asbestos material,
normally soil or a resinous or petroleum-based dust suppression agent. An
alternative control method for emissions may be used with prior approval by
the Administrator. In addition to these federal requirements, many state or
local agencies require more stringent waste handling procedures.
b. Manufacturing and Fabricating Wastes
Asbestos products are manufactured by combining the milled asbestos
fibers with binders, fillers, and other materials. The resultant mixture is
molded, formed, and then cured or dried. Some products require further
machining or coating operations prior to their sale. This process is called
fabrication or secondary manufacture. Manufacturing and fabricating
operations generate the following four types of asbestos-containing wastes:
• Empty asbestos shipping containers;
• Process wastes such as cuttings, trimmings, and
off-specification, reject material;
• Housekeeping waste from sweeping or vacuuming; and
• Pollution control device waste from dust capturing systems.
It has been estimated that approximately 88,500 tons of asbestos-containing
wastes were generated from manufacturing/fabricating operations in 1981.
According to one source, a ratio of 0.25 tons of asbestos waste is generated
during manufacturing/fabrication operations for every one ton of asbestos
consumed (EPA 1986d).
The handling and disposal of manufacturing and fabricating wastes are
regulated under 40 CFR §61.152 and §61.156. The same standards apply during
the collection, processing, packaging, transport, and deposit of
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asbestos-containing wastes generated by manufacturing and fabricating
operations as during mining and milling operations. However, in addition,
both EPA and OSHA require that asbestos-containing wastes from
manufacturing/fabrication operations be containerized to avoid creating dust
during transport and disposal (EPA 1986e, OSHA 1986a). Both EPA and.OSHA
specify that the containers be labeled as follows:
CAUTION
Contains Asbestos Fibers
Avoid Opening or Breaking Container
Breathing Asbestos is Hazardous to Your Health
or
CAUTION
Contains Asbestos Fibers
Avoid Creating Dust
May Cause Serious Bodily Harm
EPA recommends that process wastes and housekeeping wastes be wetted
before packaging. Air pollution control device wastes are usually packaged
directly by connecting a container to the waste hopper outlet. Vacuum bags
and disposable paper filters should not be cleaned, but rather wetted and
placed intact into a proper container. EPA also recommends that empty
shipping drums not be cleaned; instead, the drums should be sealed and
properly disposed or used to contain other asbestos wastes for disposal.
Empty shipping bags can be flattened and packaged under hoods exhausting to a
pollution control device (EPA 1985a).
c. Installation Wastes
OSHA regulates installation wastes under the general category of
'construction' wastes. According to OSHA, construction operations include
installation, removal, and demolition activities. These wastes are regulated
by OSHA under 29 CFR Parts 1910 and 1926. The regulations state that "all
asbestos waste, scrap, debris, bags, containers, equipment, and contaminated
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clothing must be collected and disposed of in sealed impermeable bags or in
other closed impermeable containers" (51 FR 22725) (OSHA 1986a).
OSHA does not, however, address the ultimate disposal of these wastes
"since these wastes and their disposal are regulated by EPA" (51 FR 22726)
(OSHA 1986a). EPA, on the other hand, does not regulate the disposal of these
wastes because it considers the quantities of asbestos-containing products
currently being installed in the U.S. to be insignificant (EPA 1986C). EPA
does regulate, along with OSHA, wastes generated from demolition and
renovation operations; these regulations are discussed below.
d. Demolition and Renovation Wastes
A large amount of asbestos-containing waste may be generated during
the removal of asbestos products from buildings. As mentioned above, both EPA
and OSHA regulate demolition and renovation wastes. EPA regulations
specifically address the removal of 'asbestos-containing waste'. This term
must be understood properly in order to understand exactly which types of
wastes are regulated by EPA. According to EPA:
"Asbestos-containing waste materials means any waste that
contains commercial asbestos and is generated by a source
subject to the provisions of this subpart. This term includes
asbestos mill tailings, asbestos waste from control devices,
friable asbestos waste material, and bags or containers that
previously contained commercial asbestos. However, as applied
to demolition and renovation operations, this term includes
only friable asbestos waste and asbestos waste from control
devices" (40 CFR, §61.141, Subpart M) (EPA 1986e).
According to the above definition, asbestos waste generated during demolition
and renovation operations is considered 'asbestos-containing waste' (and is,
therefore, regulated) only if the waste is friable.* For example, waste
generated during asbestos-cement pipe manufacture is regulated under 40 CFR,
* Friable asbestos material refers to "any material containing more than
1 percent asbestos by weight that hand pressure can crumble, pulverize, or
reduce to powder when dry" (40 CFR, §61.141, Subpart M).
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Subparc M; however, waste gent^acta during the removal of this same product is
not regulated. It has been estimated that approximately 12,700,000 tons of
asbestos-containing wastes have been generated during demolition and
renovation operations between the years 1880 and 1985 (EPA 1986d).
EPA and OSHA regulations require that when the asbestos materials are
removed, they be containerized to avoid creating dust during transport and
disposal. The generally recommended containers are 6-mil thick plastic bags,
sealed in such a way to make them leak-eight. More thorough containerization
may include double bagging, plastic lined cardboard containers, or plastic-
lined metal containers. Asbestos waste slurries may be too heavy for plastic
bags, and can be packaged in leak-tight drums. In situations where pipes or
other facility components are removed as sections without first removing the
asbestos, 6-mil plastic can be used to wrap the section sufficiently to create
a leak tight container (EPA 1985a). The sane requirements for handling and
disposing of manufacturing wastes apply to demolition and renovation
'asbestos-containing wastes'.
After the asbestos-containing materials have been removed, all plastic
barriers should be removed and the facility should be thoroughly washed. The
plastic used to line the walls, floors, etc. should be treated as asbestos
waste and containerized appropriately. Any asbestos-containing wastes
collected by cleaning devices must be appropriately bagged, labeled, and
disposed.
2. Emission Estimates from Mining/Milling Waate Piles
Due to the regulated handling of wastes from manufacturing and
fabrication, installation, and demolition and renovation of asbestos products,
emission of asbestos from these wastes is not expected to be significant.
Wastes from these operations are containerized for disposal in landfills; and
should not, therefore, emit asbestos unless the containers are damaged.
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Asbestos emissions are most likely from mining and milling wastes which
are not containerized, but are instead disposed on-site in waste piles or
trenches. Furthermore, mining wastes are not expected to emit significant
quantities of asbestos because of their low asbestos content (approximately
0.1 percent). Therefore, only emissions of asbestos from milling wastes
(i.e., tailings and air cleaning device wastes) are estimated. Note that the
quantity of air cleaning device waste is small compared to the quantity of
tailings; air cleaning device wastes only account for about 3 percent of the
total waste from the mills.
Very little data on actual emissions from asbestos waste disposal
operations exist. For this reason, the Emissions Standards and Engineering
Division of EPA has developed a methodology for estimating these emissions
(EPA 1986f). Emissions from the disposal of tailings have been estimated for
the three active U.S. milling operations. Following is a description of
potential emission points during asbestos waste disposal operations, the
methodology used to estimate emissions, and the resulting emission estimates.
a. Potential Emission Points During Waste Handling Operations
A summary of current waste generation and waste management
practices at the three milling facilities is shown on Table 48. Waste
management practices differ only slightly between the mills.
Tailings generated by the Vermont Asbestos Group are wetted (using water
and a dust suppression agent) and then dumped onto waste piles, located
adjacent to the mill. The process is continuous, with tailings being
transported to the waste pile via conveyor (ICF Exposure Survey 1986-1987, PEI
Associates 1984). The wetting agent prevents blowing and solidifies the
wastes for permanent storage. The wastes are, therefore, not transported to a
landfill for ultimate disposal (PEI Associates 1984, Vermont Asbestos Group
1987).
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Table 48. Summary of Current Waste Generation from Milling Operations
Vermont
Asbestos Group
(Morrisville, VT
05661)
Calaveras
Asbestos, Ltd
(Copperopolis, CA
95228)
KCAC Inc.
(King City, CA
93930)
Annual Waste
Generation
219,366 TPY
Asbestos Content <0.05%
Disposal Method
Waste pile --
tailings are
wetted
Number of Files 3
Size of Piles 100 Ac
Location of
Piles
Adjacent to the
mill
645,000 TPY
Waste pile --
tailings are
wetted
1
110 Ac
Adjacent to the
mill
13,000 TPY
Waste trench - -
covered with
earth seal
1
12 Ac
1/4 - 1/2 mile
from the mill
TPY - tons per year.
AC
acre.
aNo value for the asbestos content was obtained; therefore, we assumed the
more conservative of the two values obtained for the other mills.
Sources: ICF Exposure Survey 1986-1987, PEI Associates 1984, Vermont Asbesto
Group 1987, Calaveras Asbestos 1987, KCAC Inc. 1987, OAQPS 1987.
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Tailings from milling operations at Calaveras Asbestos are transported
from the mill via conveyor to a waste pile, located approximately 300 ft away.
Two wet screws are used to mix water and a binding agent into the tailings.
The last 150-foot section of the conveyor contains water sprays which are used
to saturate the tailings so that by the time the tailings reach the end of the
conveyor they are in the form of a slurry. The tailings are then dumped onto
the waste pile for permanent storage (Calaveras Asbestos, Ltd. 1987).
Tailings generated by KCAC Inc. are disposed in a trench, located between
1/4 and 1/2 of a mile from the mill. The trench is essentially a hole used to
bury the wastes. Due to its extensive use over the years, the stored waste
currently extends above ground. The wastes are transported via conveyor from
the mill to a dump truck and then transported to the disposal site. KCAC,
unlike the two other milling operations, uses a wet process for milling. The
tailings leave the mill as a slurry, doing away with the need to add
additional wetting agents prior to disposal. The wastes are continuously
delivered to the disposal site. The tailings are covered with two or three
feet of topsoil approximately once a month to prevent erosion and exposure.
They are not covered more frequently since they are wetted and solidify into a
crusty material when dry (KCAC Inc. 1987).
There are three points along the waste disposal process from which
potential emissions may occur; they are as follows:
1. Transfer of tailings onto and between conveyor systems;
2. Dumping of tailings from the conveyor system/dump truck
onto the waste pile; and
3. Wind erosion from the waste pile.
It is assumed that as a result of the use of dust suppressants, emissions
during the transferring and dumping of mill waste would be nonexistent (OAQPS
1987). Emissions from waste piles would be very low; however, they are not
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expected to be zero due to the effects of wind erosion. The methodology used
to estimate these emissions is described below.
b. Methodology
Emissions from tailings disposal are estimated using the
methodology presented by EPA in the publication 'National Emission Standards
for Asbestos -- Background Information for Proposed Standards' (OAQPS 1987).
The equations were derived empirically for operations other than asbestos
waste disposal and then modified based on comments submitted by industry,
experts on fugitive emissions, and environmental groups. An equation used to
calculate emission factors for wind erosion from sand and gravel aggregate
storage piles was used to develop emission factors for wind erosion from
asbestos disposal sites; this equation is:
E - (1.9) (JL) (365'?) <1>
1.5 235 15
where;
E - Emissions factor (kg/day/hectare (ha))
S - Silt content (%)
P - Number of days/year at site with more than 0.01 inches
of precipitation
F - Percentage of time wind speed exceeds 5.4 m/sec at the site.
The emission factor is then used to estimate emissions as follows:
Emissions (kg/yr) - E (365 **?s^ G A
(10,000 mVha) H D (100)
where;
E - Emissions factor (kg/day/ha)
G - Annual waste generation (Mg/yr)
A - Asbestos content of waste (%)
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H - Height of waste pile (m)
D - Bulk density of waste (Mg/m3).
The equation assumes no emission control. It is likely that actual emission
values would be much less than the estimates calculated because of the use of
dust suppressants or earth seals, the growth of vegetation, and crusting
(OAQPS 1987).
c. Emission Estimates
The parameters used to calculate emission factors for wind erosion
are shown in Table 49. No measured data were available for the silt content
or the percentage of time wind speed exceeds 5.4 m/s; therefore, we used the
same estimates used by OAQPS (1987). Data on the number of days with rainfall
exceeding 0.01 inches was found in the National Climatic Center's publication,
'Local Climatological Data' (NOAA 1979). Climatological data summaries are
presented for various cities throughout the country. Summary sheets were not
available for the towns in which the disposal sites were located; therefore,
data was taken for the closest city/town. The cities chosen and their
distances from the disposal sites are also shown in Table 49.
Resulting emission estimates are shown in Table 50. As one can see from
the table, emissions are low. As discussed earlier, the equations used to
calculate emissions do not factor in the use of controls. For this reason,
the values shown in Table 50 are actually higher than would be expected at the
disposal sites.
The highest emission estimate from waste disposal operations was found to
be 7.99 kg/yr. This is 35 times less than levels typically found during
milling operations (approximately 280 kg/yr). One of the reasons for this is
the extensive use of dust suppressants and binding agents during waste
disposal operations. If the wastes are not already wetted as they leave the
mill, water and other dust suppressants are added to create a slurry. When
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Table 49. Parameters for Estimating Emissions Resulting from Wind Erosion
Emission Parameters
Vermont
Asbestos Group
(Morrisville, VT
05661)
Calaveras
Asbestos, Ltd
(Copperopolis, CA
95228)
KCAC Inc.
(King City, CA
93930)
Percent silt content (S)
Number of days with
rainfall exceeding
0.01 in (P)a
Percent of time wind
speed exceeds 5.4 m/s
(F)
Asbestos emission
factor (kg/day/ha)
2
153
24
3.657
2
52
24
5.399
2
44
1.846
aClimatological data for Burlington, VT was used for the Vermont Asbestos
Group; Burlington is located approximately 30 miles from Morrisville.
Climatological data for Stockton, CA was used for the Copperopolis Mine;
Stockton is located approximately 35 miles from Copperopolis. Climatological
data for Fresno, CA was used for KCAC Inc.; Fresno is located approximately 80
miles from King City.
-Sources: NOAA 1979, OAQPS 1987.
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Table 50. Emission Estimates from Milling Waste Piles
Emission Parameters
Vermont
Asbestos Group
(Morrisville, VT
05661)
Calaveras
Asbestos, Ltd
(Copperopolis, CA
95228)
KCAC Inc.
(King City, CA
93930)
Emission factor
(kg/day/ha) (E)
Height of waste pile
On) (H)a
Bulk density of waste
(Mg/m3) (D)b
Annual waste generation
(Mg/yr) (G)
Asbestos content of
waste (%) (A')c
Emissions (kg/yr)
3.657
46
1.121
<
199,200
0.05
0.258
5.399
88
1.642
585,700
1.0
7.99
, 1.846
20
1.121
11,800
1.0
0.355
aThe heights of the waste piles at the Morrisville and Copperopolis milling
operations were obtained directly from the mills (Vermont Asbestos Group 1987,
Calaveras Asbestos 1987); however, similar data was not available for KCAC
Inc. Therefore, we assumed the value estimated by OAQPS (1987).
"The densities of the wastes generated at the two California mills were
obtained directly from the mills (Calaveras Asbestos 1987, KCAC Inc. 1987).
We used the most conservative number of the two for the Vermont mill, for
which we did not have data.
cThe asbestos content of the tailings was obtained directly from the Vermont
and Copperopolis mills (ICF Exposure Survey 1986-1987, Calaveras Asbestos
1987). The most conservative of these two numbers was used for KCAC Inc., for
which data was not obtained.
Sources: OAQPS 1987, Vermont Asbestos Group 1987, Calaveras Asbestos 1987,
KCAC Inc. 1987, ICF Exposure Survey 1986-1987.
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the slurry dries, it solidifies forming a crusty material which effectively
controls emissions.
The low asbestos content of the wastes is also a contributor to the low
asbestos emission rates. Fibers that become airborne during milling
operations are usually released from material being processed for use. Fiber
released during waste disposal operations are typically released from reject
material (i.e., material whose asbestos content was too low for use).
Only limited monitoring has been done by the milling companies. KCAC Inc
has found that emissions downwind of the disposal site are less than
0.005 f/cc using phase contrast microscopy. The sample was taken at the edge
of their property, approximately 1/4 of a mile from the site (KCAC Inc. 1987)
Area samples taken by Calaveras Asbestos yielded non-detectable levels, using
a method with a lowest detectable limit of 0.15 f/cc (Calaveras Asbestos, Ltd
1987). We are not aware of any testing done by the Vermont Asbestos Group.
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REFERENCES
Addingly CG. 1966. Asbestos dust and its measurement. Ann. Occup. Hyg.
9:73-82.
Aherne J. 1980. Evaluation of asbestos exposure from asbestos-roofing
removal operations. Submitted to Professor Lester Levin, Dept. of Industrial
Hygiene, Drexel University. October 27, 1980.
AIA. 1986. Asbestos Information Association response to EPA, Office of Air
Quality Planning and Standards. Letter from Kenneth E. Nyquist of AIA to Jack
Farmer of EPA. March 21, 1986.
Air Resources Board (State of California). 1986. Technical Support Document.
Public hearing to consider the adoption of a regulatory amendment identifying
asbestos as a toxic air contaminant.
Anderson PH, Grant MA, Mclnnes RG, Farino VJ. 1982. GCA Corporation.
Analysis of fiber release from certain asbestos products. Draft final report.
Washington, D.C.: Office of Pesticides and Toxic Substances, U.S.
Environmental Protection Agency. Contract 68-01-5960.
Anderson et al. 1983. Asbestos industry profile, trends and outlook, and
substitute products analysis. Draft Report. Washington, D.C., U.S.
Environmental Protection Agency. Office of Pesticides and Toxic Substances.
Argonne National Laboratory. 1981 (December 7). Asbestos fiber measurements
during the Nilfisk Power and Vacuum Demonstration (August 30, 1979). Memo
received by GCA/Technology Division, from Bruce Newman, Nilfisk of America,
Inc., King of Prussia, PA.
Asbestos Information Association/North America. 1986. Recommended work
practice procedures for asbestos-cement sheet. Submittal to U.S.
Environmental Protection Agency, Office of Toxic Substances, in response to
Commercial and Industrial Use of Asbestos Fibers: Advance Notice of Proposed
Rulemaking. EPA Docket Number OTS 61005.
ASHRAE Handbook. 1977. American Society of Heating, Refrigerating and Air
Conditioning Engineers. New York, New York. Chapter 21, Infiltration and
Ventilation.
ATA. 1985, 1987. American Trucking Association. Telephone conversations
with Mr. Larry Strawhorn, Engineering, Alexandria, VA, on December 13, 1985,
and February 4, 1987.
Augustyniak CM. 1987 (July). Economics and Technology Division, Office of
Toxic Substances (OTS), U.S. EPA. Choice of summary statistic for exposure
work relating to asbestos ban/phasedown. Memorandum to Elizabeth Margosches
of the Exposure Evaluation Division, OTS, U.S. EPA.
Autio JE. 1986. Mine Safety and Health Specialist, Mine Safety and Health
Administration. Telephone conversation on November 12, 1986.
- 217 -
-------
Axecell K, Jr., Cowherd C. 1984. Improved emission factors for fugitive dus"
from western surface coal mining sources. Prepared by PEDCo Environmental,
Inc. and Midwest Research Institute for U.S. Environmental Protection Agency,
Office of Air Quality Planning Standards and Industrial Environmental Researcl
Laboratory in Cooperation with the Office of Surface Mining. Publication No.
EPA-600/7-84-048. March 1984.
Ayer HE, Lynch JF, Fanney JH. 1965. A comparison of impinger and membrane
filter techniques for evaluating air samples in asbestos plants. Ann. NY Aca<
Sci 132:274-287.
Beattie J, Knox JF. 1961. Studies of mineral content and particle size
distributions in the lungs of asbestos textile workers. In Inhaled Particles
and Vapours (CN Davies, ed.), Pergamon Press, Oxford, England.
Bloomfield JJ, Dallavalle JM. 1935. The detemination and control of
industrial dust. Public Health Bull. 217.
Bellinger N. 1987. Representative, KIOSH Safety Research. Telephone
conversation on February 6, 1987.
Bragg G. 1986 (June 29). Exposure to asbestos: an analysis of the technica.
aspects of the Environmental Protection Agency proposal to ban and phase out
asbestos.
Calaveras Asbestos, Ltd. 1987. Telephone conversations with Joey Toney,
Director - Environmental Affairs, Copperopolis, CA during March 1987.
Canadian Asbestos Information Center (A.I.C.). 1979. Brochure explaining thf
use of asbestos flooring products.
Cha S, Carter P. 1982. Estimation of urban automobile brake emissions
through simulation of wear dynamics. Submitted to Mobile Source Emissions
Research Branch, Environmental Science Research Laboratory, U.S. Environmental
Protection Agency, Research Triangle Park, NC, under Contract 68-02-2566.
Research Triangle Park, NC: Northrop Services, Inc., Environmental Sciences,
P. 1.
Chatfield EJ. 1983. Measurements of asbestos fiber concentrations in ambient
atmospheres. Study No. 10. Report of the Royal Commission on Matters of
Health and Safety Arising from the Use of Asbestos in Ontario. Ontario
Ministry of Government Services, Publication Services Branch, Toronto,
Ontario, Canada.
Chemical Business. 1985 (September). Chlorine/caustic: anatomy of a
struggle.
Chemical Engineering. 1976. New signs point to wider use of synthetic-
membrane chlor-alkali cells. (March 29):61.
Chemical Engineering. 1986. Makers of gaskets, packing try asbestos
replacement. October 27:23-25.
Chemical Week. 1982. A revolution in chlor-alkali membranes. November 17,
1982:35-36.
- 218 -
-------
Chemical Week. 1985. Better times for chlor-alkali in 1986. (February
1):28.
Chemical Week. 1986. Dow shuts some chlorine capacity. (July 23):24.
Chilton Book Co. 1987. Telephone conversation with Mr. Robert McAnally,
Editor, Radnor, PA, on February 4, 1987.
Chlorine Institute. 1986a. Comments of the Chlorine Institute, Inc. The
Chlorine Institute, Inc. 70 West 40th Street, New York, NY. June 30, 1986.
Chlorine Institute. 1986b. Questionnaire to the Chlorine Institute". The
Chlorine Institute, Inc., 70 West 40th Street, New York, NY. Docket OPS
62036.
Clarke G. 1986. Certainteed in profile: Tackling the asbestos cement
dilemma. Industrial Minerals. April 1986.
Coats V. 1983. Vulcan Materials. Telephone conversation on July 1, 1983.
Cogley D et al. 1981 (May). The experimental determination of asbestos fiber
size distribution during simulated product use. Final Report prepared by
GCA/Technology Division for the U.S. Environmental Protection Agency. Office
of Toxic Substances, Washington, D.C.
Commins BT. 1985. The significance of asbestos and other mineral fibers in
environmental ambient air. Scientific and technical report. STR 2. Commins
Associates, Berkshire, England.
CONSAD. 1984. CONSAD Research Corporation and Clayton Environmental
Consultants, Inc. Asbestos task order for construction alternatives. Final
Report. Washington, D.C.: Occupational Safety and Health Administration,
U.S., Department of Labor. Contract J-9-F-4-0024.
Cordova B. 1987. Telephone conversation between Bob Cordova, Environmental
Division of J-M Sales Corp., Denver, CO, and ICF Incorporated. April 6, 1987.
CPSC. 1983. Chronic Hazard Advisory Panel on Asbestos. U.S. Product Safety
Commission, Directorate for Health Sciences, Washington, D.C. (OSHA EX
84-256).
Diamond Shamrock. 1986 (June 26). Letter to U.S. Environmental Protection
Agency from Diamond Shamrock Chemicals Co., Irving, TX.
Donahue R. 1987. Telephone conversation between Robert Donahue, Safety
Superintendent, Occidental Chemical Corp., Tacoma, WA, and ICF Incorporated.
April 8, 1987.
Dunnigan J, LeBel J. 1985. Asbestos exposure in the workplace: recent data
for asbestros roofing felt handling and relationship to the existence of a
threshold. New Orleans, LA. February 10-13, 1985. National Roofing
Contractors Association, 98th Annual Convention.
Durham J. 1987. Telephone conversation between Joe Durham, Compliance
Officer at OSHA Atlanta area office and ICF Incorporated, February 9, 1987.
- 219 -
-------
Edminster D. 1987. Telephone conversation between Dave Edminster, Quality
Assurance Manager, Lydall Inc.. Covington, TN, and ICF Incorporated. April 7
1987.
EPA. 1977. Compilation of Air Pollutant Emission Factors. Section 11.2.
Fugitive Dust Sources. EPA Publication No. AP-42, Part B. Research Triangle
Park, North Carolina. August 1977.
EPA. 1982. Summary of information collected under the asbestos reporting
regulation (40 CFR Part 763, Subpart D).
EPA. 1985a (May). Asbestos waste management guidance: generation,
transport, disposal. U.S. Environnental Protection Agency, Office of Solid
Waste.
i
EPA. 1985b (December). Report co Congress: wastes from the extraction and
beneficiation of metallic ores, phosphate rock, asbestos, overburden from
uranium mining, and oil shale. U.S. Environnental Protection Agency, Office
of Solid Waste and Emergency Response.
EPA. 1986a (July 29). EPA Memorandum entitled "Methodology for calculating
asbestos emission rates from Section 8(a) data." Exposure Assessment Branch,
EPA.
EPA. 1986b (June 17). EPA Memorandum entitled "8(a) Asbestos aggregate
statistics report." Intra-agency memorandum from S. Shapiro to D. Devoe,
Confidential Data Branch. IMD, OTS.
EPA. 1986c. Telephone conversations with John Copeland, Office of Air
Quality, Planning, and Standards, Research Triangle Park, NC during October
1986.
EPA. 1986d. Asbestos waste estimates. Office of Air Quality, Planning, and
Standards, Research Triangle Park, NC.
EPA. 1986e (July 1). Protection of the environment. 40 CFR Part 61,
Subpart M.
EPA. 1986f (July IS). National emission standards for asbestos -- background
information for proposed standards. Emission Standards and Engineering
Division, Research Triangle Park, NC.
EPA. 1986g. U.S. Environmental Protection Agency. Airborne asbestos health
assessment update. Washington. D.C.: USEPA. EPA/600/8-84/003F.
EPA. 1987 (January 8). Telephone conversation with John Copeland of EPA.
Office of Air Quality Planning and Standards, Research Triangle Park, North
Carolina.
EPA. n.d. Exposure to asbestos fron secondary processing. Confidential
Business Information (Document Control No. 638600018).
- 220 -
-------
Equitable Environmental Health, Inc. 1977 (December 15). Dust exposures
during the cutting and machining of asbestos/cement pipe, additional studies.
Prepared for the A/C Pipe Producers Association. OSHA Docket No. H-033C,
Exhibit No. 84-279.
Evans J, Cooper D. 1980. An inventory of particulate emissions from open
sources. Journal of the Air Pollution Control Association, Volume 30, No. 12.
December 1980.
Fenner E. 1980. Correspondence between Edmund Fenner, Vice President of
Health, Safety, and Environment Dept., Johns-Manville Sales Corp., and Lester
Levin, Drexel University, on January 14, 1980.
Freimanis I. 1981. Packing materials. In: Kirk-Othmer Encyclopedia of
Chemical Technology, Third Edition. Vol. 16. New York: John Wiley & Sons,
pp. 725-742.
Hammond YY, Diem J, Weill H. 1979. Evaluation of dust exposure in asbestos
cement manufacturing operations. Am. Ind. Hyg. Assoc. J. 40:490-495 (OSHA Ex.
84-248).
Hendrickson G, Doria J. 1983 (April 29). Versar Inc. Asbestos 8(a) data
evaluation. Memorandum to M. Callahan and L. Delpire, U.S. EPA.
Hunter Publishing Co. 1985. Service job analysis. Des Plaines, IL: Hunter
Publishing Co., pp. 24-25.
Hunter Publishing Co. 1986. Telephone conversation with Mr. Gene Zack,
Promotion and Research Manager, Des Plaines, IL, on November 26, 1986.
Hwang CY. 1981 (July ). Size and shape of airborne asbestos fibers in mining
and mineral processing environments. Thesis submitted to the Faculty of
Graduate Studies in partial fulfillment of the requirements of Doctor of
Philosophy. Department of Mining and Metallurgical Engineering. McGill
University. Montreal, Quebec.
ICF. 1984. Asbestos products and their substitutes. Washington, D.C., U.S.
Environmental Protection Agency, Office of Toxic Substances. July 3, 1984.
ICF. 1986a. Potential occupational exposure to durable fibers due to
substitution for asbestos fibers. Prepared for Chemical Engineering Branch,
Office of Pesticides and Toxic Substances, U.S. Environmental Protection
Agency, Washington, D.C.
ICF. 1986b. Durable fiber exposure assessment. Prepared for Monica Chatmon,
Chemical Engineering Branch, Office of Pesticides and Toxic Substances, U.S.
Environmental Protection Agency, Washington, D.C.
ICF. 1987. Use and substitutes analysis for asbestos. Draft report.
ICF Exposure Survey. 1986-1987. ICF survey on asbestos manufacturers for EPA
to identify occupational exposure and air release information.
ICF Market Survey. 1986-1987. ICF survey on asbestos manufacturers for EPA
to identify 1985 production of asbestos products.
- 221 -
-------
IIT Research Institute. 1981 (July). Characterizing baghouse performance t(
control asbestos manufacturing source emissions. U.S. Environmental
Protection Agency, Office of Research and Development. EPA-68-03-2558.
Jacko MG, Rhee SK. 1978. Brake linings and clutch facings. In: Kirk-
Othmer Encyclopedia of Chemical Technology, Third Edition. Vol. 4. NY: Jol
Wiley and Sons, pp. 202-212.
Jenkins, J. 1985. Asbestos fibers release from V/A tile. From the NAC
Journal, summer issue 1985.
Johns-Manville Corporation. 1978 (November 8). Testimony prepared for a
public hearing before the California Occupational Safety and Health Standard:
Board. Source of testimony unknown. Information supplied to GCA by
Johns-Manville Corporation, Denver, CO.
Johns-Manville Corporation. 1982. Submission of test results in letter of
May 11, 1982 from James Reis, Director, Asbestos Policy, Johns-Manville
Corporation, Denver, CO to Marc Grant, GCA/T«chnology Division.
KCAC Inc. 1987. Telephone conversations with John Myers, Product and
Production Manager, King City, CA during March 1987.
Kemmer WF, Hall FD. 1986 (October 23). Memorandum to Project File PN
3687-23: Plant Trip to Calaveras Asbestos, Ltd.
Kirk-Othmer. 1984. Encyclopedia of chemical technology. John Wiley and Sor
Publishing Co. New York, N.Y.
Krusell N, Cogley D. 1982. GCA Corp. Asbestos substitute performance
analysis. Revised Final Report. Washington, DC: Office of Pesticides and
Toxic Substances, U.S. Environmental Protection Agency. Contract 68-02-3168.
Lebel J. 1985 (January 22). Occupational asbestos exposure data when pullin
out asbestos roofing felt. Jacques Lebel, Technical Director of the Research
Division, Asbestos Institute.
Lebel J. 1987. Telephone conversation between Jacques Lebel, Technical
Director, Sherbrooke University, Quebec, Canada, and ICF Incorporated. April
6, 1987.
Lynch JR, Ayer HE, Johnson DL. 1970. The interrelationships of selected
asbestos exposure indices. Am. Ind. Hyg. Assoc. J. 31:598-604.
Manosh H. 1986. President, Vermont Asbestos Group. Telephone conversation
on November 14, 1986.
Means. 1983. Man-hour standards. Kingston, MA: Robert Snow Means Company,
Inc.
MSHA. 1986 (November 14). Personal exposure samples. Department of Labor.
Mine Safety and Health Administration.
Murphy RL, et. al. 1971. Floor Tile installation as a source of asbestos
exposure. From the American Review of Respiratory Disease, Volume 104.
- 222 -
-------
MVMA. 1986. Motor Vehicle Manufacturers Association. MVMA motor vehicle
facts and figures '86. Detroit: MVMA.
Myers JL. 1985. Product and Production Manager, KCAC Incorporated. Letter
to Jack Fanner, U.S. Environmental Protection Agency, on June 6, 1985.
Myers JL. 1986a. Product and Production Manager, KCAC Incorporated. Letter
to Mark Wagner, ICF Incorporated, on October 21, 1986 with attachments.
Myers JL. 1986b. Product and Production Manager, KCAC Incorporated.
Telephone conversation on November 17, 1986.
Myers JL. 1987. Product and Production Manager, KCAC Incorporated.
Telephone conversation on February 17, 1987.
Myers WR. n.d. National Institute for Occupational Safety and Health.
Strategy for recommending respirators for control of exposures to substances
undergoing premanufacturing notice (PMN) review. Washington, D.C.: Office of
Toxic Substances, U.S. EPA. Contract No. EPA DW 75932235.
National Roofing Contractors Association Newsletter. 1974. Airborne
asbestos: test results.
NIOSH. 1976. National Institute for Occupational Safety and Health. Revised
recommended asbestos standard. Cincinnati, OH: NIOSH. PB-273965.
NIOSH. 1977. Manual of analytical methods. 2nd Edition, Vol. 1, P&CAM No.
239.
NIOSH. 1979a (August). National Institute for Occupational Safety and
Health. Hazard Evaluation and Technical Assistance Report No. TA 79-31.
Poole Construction Company, Denver, CO.
NIOSH. 1979b. National Institute for Occupational Safety and Health, Report
No. 79-95-613, Federal-Mogul Corp., Gallipolis, OH. September 1979.
NIOSH. 1979c. National Institute for Occupational Safety and Health. Health
Hazard Evaluation Report HE 78-73-612, Kentile Floors, Inc., Chicago, IL.
NIOSH. 1979d. National Institute for Occupational Safety and Health. Health
Hazard Evaluation Report HE 78-71-633, Kentile Floors, Inc., Brooklyn, NY.
NTIS. PB80-195308.
NIOSH. 1979e. National Institute for Occupational Safety and Health.
Industrial hygiene assessment of seven brake servicing facilities. By P
Johnson, RD Zumwalde, DR Roberts. Cincinnati, OH: NIOSH.
NIOSH. 1980a. National Institute for Occupational Safety and Health. Report
No. 79-151-657, Dearborn Rubber Corporation, Westmont, IL. January 1980.
NIOSH. 1980b. National Institute for Occupational Safety and Health. Report
No. 78-79-736, Cissell Manufacturing Co., Louisville, KY. August 1980.
- 223 -
-------
wioan. J.yauc. National Institute for Occupational Safety and Health.
Industrial hygiene report: Asbestos at Allied Brake Shop, Cincinnati, OH. B-
Roberts DR. Cincinnati, OH: NIOSH. PB81-241879.
NIOSH. 1980d. National Institute for Occupational Safety and Health.
Industrial hygiene survey report of the New York City sanitation, traffic, an
police brake servicing facilities, Queens, New York. By DR Roberts, RD
Zumwalde. Cincinnati, OH: NIOSH.
NIOSH. 1981a (January). National Institute for Occupational Safety and
Health. HETA 81-038-801. Hensel Phelps Construction Company, Greeley, CO.
NIOSH. 1981b. National Institute for Occupational Safety and Health. HETA
81-407-993, Grundy Industries. Denver. CO. Springfield. VA:. NTIS.
PBS-18701.
NIOSH. 1982a (October). Walk-thru survey report of Calaveras Asbestos, Ltd.
at Copperopolis, California. Cincinnati, Ohio: National Institute for
Occupational Safety and Health.
NIOSH. 1982b. Industrial hygiene summary report of asbestos exposure
assessment for brake mechanics. By Roberts DR, Zumwalde RD. Cincinnati, OH:
National Institute for Occupational Safety and Health.
NIOSH. 1982c. National Institute for Occupational Safety and Health. Healtl
Hazard Evaluation Report No. HETA 81-100-1140. Raybestos Friction Materials
Company, Crawfordsville, IN. Springfield, VA: NTIS. PB84-139880.
NIOSH. 1982d. National Institute for Occupational Safety and Health. Healtl
Hazard Evaluation HETA 82-270-1238, Drive Train Industries, Inc., Denver, CO.
Cincinnati, OH: NIOSH.
NIOSH. 1982e. National Institute of Occupational Safety and Health. HETA
81-477-1192, Grundy Industries, Inc., Joliet, IL. Springfield, VA: NTIS.
NIOSH. 1983a. National Institute for Occupational Safety and Health, Report
No. 83-275-1394. Kautt & Bux Manufacturing, Mundelein, IL. December 1983.
NIOSH. 1983b. National Institute for Occupational Safety and Health, Report
No. 79-040-1381. Pennwalt Corp., Portland, OR. October 1983.
NIOSH. 1983c. National Institute for Occupational Safety and Health.
Walk-Through Survey Report, Control Technology for Celotex Corporation, Perth
Amboy, NJ. Springfield, VA: NTIS. PB84-184597.
NIOSH. 1984a. National Institute for Occupational Safety and Health.
In-Depth Survey Report: Control Technology for Solids Material Handling at
General Motors Corporation, Inland Division, Vandalia, OH. Springfield, VA:
NTIS. PB85-221265.
NIOSH. 1984b. National Institute for Occupational Safety and Health. Health
Hazard Evaluation Report HETA 84-028-1517, Drive Train Industries, Inc.,
Albuquerque, NM. Springfield, VA: NTIS. PB85-208353.
- 224 -
-------
NIOSH. 1984c. National Institute of Occupational Safety and Health.
In-Depth Survey Report, Control Technology for Richard Klinger, Inc.
Cincinnati, OH: NIOSH. Report #144-15b.
NIOSH. 1984d. National Institute of Occupational Safety and Health. Health
Hazard Evaluation Report HETA 83-438-1479, Grundy Industries, Inc. Joliet,
IL. Springfield, VA: NTIS. PB85-220960.
NIOSH. 1984e. Health Hazard Evaluation Report HETA 84-074-1476, Grundy
Industries, Inc., Denver, CO. Springfield, VA: NTIS. PB85-187698.
NIOSH. 1984f. National Institute of Occupational Safety and Health, Report
No. 82-280-1407. Hoover Co., North Canton, OH. January 1984.
NIOSH. 1985a (May). National Institute for Occupational Safety and Health.
HETA 84-321-1590, Asbestos Shingle Tear-Off. Rockford, Illinois sampled on
May 12, 1984.
NIOSH. 1985b. National Institute for Occupational Safety and Health. Health
Hazard Evaluation Report HETA 84-151-1544, Nuturn Corporation, New Castle, IN.
Springfield, VA: NTIS. PB86-138724.
NIOSH. 1985c. National Institute for Occupational Safety and Health. Health
Hazard Evaluation Report HETA 84-368-1624, FMC Corporation, San Jose, CA.
Springfield, VA: NTIS. PB86-191269.
NIOSH. 1987a. National Institute for Occupational Safety and Health. In-
depth survey report: evaluation of brake drum service at United States Postal
Service vehicle maintenance facility, Nashville, Tennessee. By FW Godbey et
al. Cincinnati, OH: NIOSH. Report No. ECTB152-20b.
NIOSH. 1987b. National Institute for Occupational Safety and Health. In-
depth survey report: evaluation of brake drum service controls at Cincinnati
Bell maintenance facility, Fairfax, Ohio. By JW Sheehy, WF Todd, TC Cooper,
HD Van Wagenen. Cincinnati, OH: NIOSH. Report No. ECTB152-21b.
NIOSH. 1987c. National Institute for Occupational Safety and Health.
In-depth survey report: control technology for brake drum service operations
at Ohio Department of Transportation maintenance facility, Lebanon, OH.
Cincinnati, OH: NIOSH. Report No. ECTB 152-18b.
NOAA. 1979. Local climatological data, annual summaries for 1979. National
Oceanic and Atmospheric Administration, Environmental Data and Information
Service,.National Climatic Center, Asheville, N.C.
NRC (National Research Council Committee on Nonoccupational Health Risks of
Asbestiform Fibers). 1984. Asbestiform fibers. Nonoccupational health
risks. Washington, D.C.: National Academy Press.
OAQPS. 1987 (March 5). National emission standards for asbestos --
background information for proposed standards. Draft Report. U.S.
Environmental Protection Agency, Office of Air Quality Planning and Standards.
- 225 -
-------
OSHA. 1986a (June 20). Occupational Safety and Health Administration.
Occupational exposure to asbestos, tremolite, anthophyllite, and actinolite;
Final Rules. (51 ffi No. 119, p. 22612).
OSHA. 1986b (June 11). Occupational Safety and Health Administration, Off!
of Regulatory Analysis. Final regulatory impact and regulatory flexibility
analysis of the revised asbestos standard.
OSHA. 1986c. Telephone conversation with Ira Wainless, Office of Health
Standards, Washington, DC on October 23, 1986.
OSHA. 1987 (January 12). Occupational Safety and Health Administration, U.
Department of Labor. National inspection summary report by substance: heal
sampling results by inspection. Computer print-out for 1979-1986.
PEI Associates. 1984. Site specific data summary forms.
PEI Associates, Inc. 1985. Asbestos dust control in brake maintenance.
Draft. Prepared for Office of Pesticides and Toxic Substances, U.S.
Environmental Protection Agency.
PEI Associates. 1986 (June). Operation and maintenance manual for fabric
filters. U.S. Environmental Protection Agency, Office of Research and
Development. EPA-68-02-3919.
PEI Associates. 1987. Cost of engineering controls for brake
maintenance/repair. Prepared for Office of Pesticides and Toxic Substances,
U.S. Environmental Protection Agency.
Perry R. 1973. Chemical Engineer's Handbook, 5th ed. New York: HcGrav-Hil
p. 12-27.
Phelps LG. 1987. Plant Engineer, Vermont Asbestos Group. Telephone
conversation on January 30, 1987.
PPG. 1986 (June 24). Letter to U.S. Environmental Protection Agency from P-
Industries, Pittsburgh, PA.
Precision Import Service. 1985. Telephone conversation with Pete Vandervat*
Owner, on December 11, 1985.
Reed LV. 1937. Telephone conversation between the office of L.V. Reed,
NIOSH, Cincinnati, OH, and ICF Incorporated. April 7, 1987.
Research Triangle Institute (RTI). 1984. Phase I Report. Regulatory
analysis of the proposed OSHA standard on asbestos. OSHA Docket No. H-033C.
Exhibit No. 84-473. May 1984.
Rodelsperger K et al. Estimation of exposure to asbestos-cement dust on
building sites. Study supported by the Unwelfbundesant, Berlin, Project No.
10401023/11, by the Commission of the European Community, Project No. 298-781
ENVD, and by the Bau-Berufagenossenschaften, Frankfurt.
Rose T. 1987. Telephone conversation between Tom Rose, Rose Roofing,
Arlington, Virginia, and ICF Incorporated, April 1, 1987.
- 226 -
-------
Rosenthal FS, Paull JM. 1985. The quality of respirator programs: an
analysis from OSHA compliance data. American Industrial Hygiene Association
Journal. 46(12):709-715.
Roy N et al. 1980 (February). Asbestos product test results. Draft Final
Report prepared by GCA/Technology Division for U.S. EPA, Office of Pesticides
and Toxic Substances, Washington, D.C.
Roy S. 1987. Telephone conversation with Mr. Sims Roy, Office of Air Quality
Planning and Standards on July 6, 1987.
Royal Commission. 1984. Report of the Royal Commission on matters of health
and safety arising from the use of asbestos in Ontario. Ontario Ministry of
Government Services, Publication Services Branch, Toronto, Ontario, Canada.
RTI. 1985 (August). Research Triangle Institute. Regulatory impact analysis
of controls on asbestos and asbestos products. Vol: III. Appendix J.
Prepared for U.S. EPA.
Scott SW. 1984. Asbestos substitutes in friction applications. Design News
40:6, 44-50.
Sears. 1985. Sears Roebuck and Co., Automotive Service. Telephone
conversation with Mr. Luther Budd, Brake Service, Washington, D.C., on
December 11, 1985.
Section 114 Letters. 1985. Request for information by OAQPS on the subject
of air pollution control for asbestos in primary manufacturing facilities.
Shapiro S. 1986 (June 17). Asbestos Action Program, Office of Pesticides and
Toxic Substances, U.S. Environmental Protection Agency, Washington, DC 20460.
8(a) Asbestos aggregate statistics report. Intra-agency memorandum to D.
Devoe, Confidential Data Branch, IMD, OTS.
Spurny KR, Stober W. 1978. Asbestos measurement in remote ambient air. In
Clean Air, the Continuing Challenge; Proceedings of the International Clean
Air Conference, Brisbane, Australia, pp. 373-387. Ann Arbor, Michigan: Ann
Arbor Science Publishers, Inc.
SRI International. 1985. Chlorine. In: 1984 Directory of Chemical
Producers, United States:487-488.
Syracuse Research Corp. 1978 (August). Chemical market input/output analysis
of selected chemical substances to assess sources of environmental
contamination: Task III Asbestos. Prepared for U.S. EPA." NTIS PB-285-531.
Toney J. 1986. Director of Environmental Affairs, Calaveras Asbestos, Ltd.
Telephone conversation on November 13, 1986.
Toney J. 1987. Director of Environmental Affairs, Calaveras Asbestos Ltd.
Telephone conversation on February 10, 1987.
Tzanetos et al. 1987 (July 21). Forecasts of asbestos drum and disc brake
sales for light vehicles. Memorandum from ICF Incorporated to Christine
Augustyniak of the Office of Toxic Substances, U.S. EPA.
- 227 -
-------
Vermont Asbestos Group. 1987. Telephone conversation with Lloyd Phelps, Plan
Engineer, Morrisville, VT on March 17, 1987.
Versar. 1983. Draft Final Report -- Exposure assessment for asbestos.
Prepared for the Environmental Protection Agency. Under EPA Contract No.
68-01-6271, Task No. 49. Washington, D.C.. April 29. 1983. OSHA Docket No.
H-033C. Exhibit No. 333.
Versar. 1984. Exposure assessment for asbestos. Draft Final Report.
Washington, D.C. , U.S. Environmental Protection Agency, Office of Toxic
Substances. EPA Contract No. 68-01-6271, Task No. 49.
Versar. 1987 (June 17). Nonoccupational asbestos exposure.. Revised Report
Washington, D.C.: Office of Toxic Substances, U.S. EPA. Contract No.
68-02-4254.
Verta R. 1987. Telephone conversation with Mr. Robert Verta, U.S. Bureau of
Mines. Washington. D.C. on July 6, 1987.
Vulcan Chemicals. 1986. Comments of the Vulcan Materials Company. Vulcan
Chemicals, P.O. Box 7609. Birmingham, AL 35253.
Wainless I. 1987. Telephone conversation with Ira Wainless, Office of Healt
Standards, Washington, D.C. in April of 1987.
Williams L. 1987. Telephone conversation between Lewis Williams, Plant
Engineer, Raymark Corp.. Manville, NC, and ICF Incorporated. April 7, 1987.
Wright MD et. al. 1984. Phase I Report-Regulatory analysis of the proposed
OSHA standard on asbestos. Prepared for U.S. Department of Labor, OSHA by
Research Triangle Institute, Research Triangle Park, N.C. May 1984.
Yocom, JE. 1976. Fugitive emissions problems in perspective. Paper
presented at a Symposium on "Fugitive Emissions -- Measurement and Control."
Sponsored by the Environmental Protection Agency, Hartford, Conn., May 17-19,
1976.
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APPENDIX A. OCCUPATIONAL EXPOSURE PROFILES AND AIR PF.T.EASES FOR
PRODUCTS NO LONGER PRODUCED OR USED IN THE U.S.
Based on the ICF Market Survey (1986-1987), several asbestos products are
no longer made in or imported into the United States. These products include
commercial paper, corrugated paper, rollboard, flooring felt, unsaturated
roofing felt (this product is imported), saturated roofing felt, vinyl
asbestos floor tile, and corrugated asbestos cement sheet (this product is
imported). Commercial paper, corrugated paper, rollboard, flooring felt, and
unsaturated and saturated roofing felts, were they still manufactured in the
U.S., would be included in the paper products category.
This appendix is divided into two sections: 1. Occupational Exposure,
and 2. Air Releases. Section 1 presents product and process descriptions and
an exposure profile (using geometric means of the raw data) for each of the
products no longer manufactured or used in the U.S. Relevant exposures during
primary manufacture, secondary manufacture, and construction are presented.
Since the products are not manufactured or used in the U.S. , populations would
not be exposed to the asbestos concentrations presented. However, available
data on the number of workers expected per unit of product manufactured or
mixture consumed is estimated such that a sensitivity analysis may be
performed to determine potential risk associated with the reestablishment of
these product markets.
Section 2 presents emission factors per unit of asbestos consumption for
primary manufacture, secondary manufacture, and construction. Specifics such
as zip codes necessary for modeling purposes are not presented because no
facilities are currently manufacturing or handling these products.
1. Occupational Exposure
This section presents our estimates of occupational exposure during
asbestos product manufacture and construction for the products no longer
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manufactured or used in the U.S. Each subsection presents a brief discussio
of each product, the processes used to manufacture the products or a
description of the operations, current and projected exposure levels,
populations exposed per unit of product manufactured (primary manufacturing)
or mixture consumed (secondary manufacturing), and duration and frequency of
exposure. All of the paper products are presented together because of the
similarity in the process by which they are all manufactured and, therefore,
the similarity in their associated exposure profiles.
As was done in Chapter II, projected exposure levels under the new
asbestos standard are estimated assuming that for those operations where
8-hour TWA exposures are currently above 0.2 f/cc, work practices will be
changed either with the addition of engineering controls or respirators to
reduce the exposures to 0.2 f/cc. Once the raw data have been manipulated b;
this methodology, new geometric and arithmetic mean exposures are calculated
this is the projected exposure.
a. Product Manufacture
This section presents the exposure profiles for both primary and
secondary manufacture of paper products, corrugated asbestos cement sheet, af
vinyl-asbestos floor tile, which are no longer manufactured in the U.S.
(1) Paper Products
Product Descriptions. This section provides descriptions of
those asbestos paper products no longer manufactured in the U.S. These
products include commercial paper, corrugated paper, rollboard, flooring fel<
and unsaturated (this product is imported) and saturated roofing felt.
Commercial paper includes general insulation paper and muffler paper.
These papers differ in weight and thickness and usually range from 95 to 98
percent asbestos fiber by weight, and 2 to 5 percent starch binder. Muffler
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paper contains an even larger percentage of asbestos fiber and very little
starch binder (Krusell and Cogley 1982).
Commercial paper was used to provide insulation against fire, heat, and
corrosion with minimum thickness. Muffler paper was used by the automotive
industry for exhaust emission control systems. The paper was applied between
the inner and outer skins of the muffler or converter to maintain the high
temperatures necessary for pollution control within the catalytic converter
reaction chamber and to protect the outer layer from the heat (Krusell and
Cogley 1982).
General asbestos insulation papers were used in a variety of industries.
The steel and aluminum industries used it as insulation in furnaces, in trough
linings in the smelting process, and against hot metal and drippings of molten
metal. Asbestos paper was also used in the glass and ceramic industry for
kiln insulation, in foundries as mold liners, and in the electrical parts and
appliance industry for electrical insulation.
Corrugated paper is a type of commercial paper which is corrugated and
cemented to a flat paper backing, and is sometimes laminated with aluminum
foil. It is manufactured with a high asbestos content (95 to 98 percent by
weight) and a starch binder (2 to 5 percent) (Krusell and Cogley 1982).
Corrugated asbestos paper was used as a thermal insulator for pipe
coverings and as block insulation. The paper could be used for appliance
insulation up to 270°F, hot-water and low-pressure steam pipe insulation, and
process line insulation.
Rollboard is a thin and flexible material composed basically of two sheets
of paper laminated together with sodium silicate. It can be cut, folded,
wrapped, and rolled, and can go around sharp corners. Asbestos rollboard was
used to protect against fire, heat, corrosion, and moisture.
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The primary constituent of asbestos rollboard is asbestos fibers, with the
balance consisting of binders and fillers. The asbestos content ranges from
60 to 95 percent by weight; 70 to 80 percent asbestos is considered typical.
Frequently used binders are starches, elastomers, silicates, and cement;
mineral wool, clay, and lime act as fillers (Krusell and Cogley 1982).
Flooring felt is a paper product which was used extensively as a backing
for vinyl sheet flooring products. It was also used as an underlay for other
flooring surfaces. The latter use accounted for a small fraction of the total
quantity of felt used. Desirable features of this product are its dimensional
stability and high moisture, rot, and heat resistance. Dimensional stability
refers to the ability of the flooring to stretch and contract with temperature
changes and "settling" of the floor deck. The flooring should be able to
withstand these conditions without cracking, warping, or otherwise
deteriorating. Asbestos backing is particularly useful in prolonging floor
life when moisture from below the surface is a problem (Krusell and Cogley
1982).
Asbestos flooring felt is composed of approximately 85 percent asbestos
and 15 percent latex binder. The latex binder is usually a styrene-butadiene
type, although acrylic latexes have been used.
All unsaturated roofing felt is used in the production of saturated
roofing felt. Unsaturated roofing felts used to be manufactured at centrally
located plants and then usually shipped to various geographical locations
nearer to demand. The felts were then saturated with coal tar or asphalt at
these locations, rather than at the central location, because of the shipping
cost; it is much cheaper to ship unsaturated roofing felt.
Unsaturated asbestos roofing felt is composed of 85 to 87 percent
asbestos, 8 to 12 percent cellulose fibers, and 3 to 5 percent starch fibers
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by weight. Other materials such as wet and dry strength polymers, Kraft
fibers, fibrous glass, and mineral wool may also be used as fillers.
Saturated roofing felt is used for built-up roofing. "Built-up" refers to
the practice of layering paper lengths on top of each other while hot roofing
tar or asphalt is mopped between layers for adhesion and/or additional weather
protection (Krusell and Cogley 1982). There are three basic types of built-up
roofing: gravel surface, smooth surface, and mineral surface. The felt is
either single- or multi-layer grade; fiberglass filaments or wire strands may
be embedded between felt layers for reinforcement. The felt's thickness or
grade and the amount of asphalt coating required depend on the product's
intended use.
Asbestos is used in roofing felts because of its dimensional stability and
resistance to rot, fire, and heat. Rot resistance is particularly important
because of roofing felt's use on flat or nearly flat roofs with poor drainage.
Given the rapid heating and cooling of roof surfaces, some cracking may occur,
allowing water to penetrate, particularly in damper climates or in areas where
snow, subject to periodic melting, has accumulated on the rooftop. Asbestos
felt resists cracking.
Process Descriptions. The main operations in all asbestos
paper manufacturing are receiving, bag opening, mixing, forming, and
finishing. In the fiber introduction operation, raw asbestos is most often
introduced in unopened pulpable bags, although for certain types of paper the
fiber is dumped from the bags. In cases where the fiber is dumped from the
bags, asbestos is obtained in non-compressed pulpable bags so that the bags
may be slit and the asbestos added directly to the mixer. At the mixer stage,
the fiber is immediately wetted.
As in other manufacturing processes, the asbestos fiber is carried under
negative pressure by conveyor to the mixer. There, the fiber is wet-mixed
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with paper stock, binder, and other ingredients. The stock slurry flows into
the papennaking machine and forms a sheet. The solids content of this sheet
may be less than five percent; the moisture content of this sheet is reduced
greatly during transit through the paper machine. The wet nature of the
material precludes the release of asbestos fiber.
The forming of asbestos paper is completed during the drying, slitting,
and calendering stages. The final operation involves rewinding in which the
paper products are bulk packaged on spools, reels, or beams from the larger
rolls. Rewinding is a dry operation.
Final fabrication may involve cutting, trimming, and shaping to meet the
requirements of the space into which the paper product is to be installed.
Secondary manufacturing is performed on all of these paper products.
There are certain manufacturing procedures that are specific to the
individual products within the paper products category, although most of the
operations are similar if not identical.
Commercial and corrugated paper are both manufactured using conventional
papennaking machines. Corrugated paper further passes through a corrugation
machine which produces the corrugated molding on the surface of the paper.
Rollboard is manufactured in a process similar to that used for millboard,
but it is produced in a continuous sheet. A conventional cylinder paper
machine, with minimal changes when necessary, can be adapted for rollboard
production. The wet mixture of asbestos fiber and chemical additives is dried
before being cut and shaped to size.
Asbestos felt-backed vinyl sheet flooring is composed of three products:
the asbestos flooring felt backing, the coating on the felt, and the wear
layer. The major steps in the manufacture of asbestos felt-backed vinyl sheet
flooring are the production of flooring felt, coating, printing, fusion,
trimming, and packaging: The flooring may be manufactured at the same plant
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as the sheet backing or in a separate facility. Asbestos flooring felt is
manufactured on conventional paperoaking machines. During manufacture, the
asbestos fibers are coated with latex and are reported to be fully
encapsulated when the sheet backing is ready to be coated with vinyl. The
asbestos felt roll is fed into the coating machinery, coated with vinyl, and
possibly decorated by various printing techniques. The vinyl plastisol can
then be colored by various additives or techniques. The printed sheet then
goes to a fusion step where the sheet is coated with another layer of material
called the "wear layer." The wear layer is a homogeneous polymer application
that provides an impervious surface for the finished product. The coated and
printed sheet is dried by a fusion oven at temperatures of at least 250cF for
the copolymers, and 300"F for the homopolymers. Chill rolls made of
chrome/plated steel remove most of the heat from the laminate. After fusion,
these layers remain distinct but are no longer chemically or mechanically
separable. The sheet flooring may be further decorated by various chemical or
printing methods before or after cooling (Krusell and Cogley 1982).
Asbestos roofing felt is manufactured on conventional papermaking machines
and then saturated with asphalt or coal tar. The felt is pulled through a
bath of hot asphalt or coal tar until it is thoroughly saturated. After
saturation, the felt passes over a series of hot rollers to set the asphalt or
coal tar into the felt. It may, on occasion, be coated with extra surface
layers of asphalt or coal tar. After saturation and coating, the felt passes
over a series of cooling rollers that reduce the paper's temperature and
provide a smooth finish. Paper given extra coats of asphalt or coal tar must
be treated to prevent adhesion between layers when the felt is rolled. The
felt is then air-dried, rolled, and packaged for marketing (Krusell and Cogley
1982).
- 235 -
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Production and Employment. Currently, no workers are exposed
to asbestos during primary and secondary manufacturing of commercial paper,
corrugated paper, rollboard, flooring felt, and roofing felt because these
products are no longer produced in the U.S. (IGF Market Survey 1986-1987).
However, based on historical data from the TSCA Section 8(a) submissions (EPl
19B6b), the average number of workers who would be exposed per unit 'of
asbestos product manufactured or mixture consumed for each product is:
Primary Manufacture
(workers/1,000 tons
produced)
Secondary Manufacture
(workers/1,000 tons
consumed)
Commercial Paper
Corrugated Paper
Rollboard
Flooring Felt
Unsaturated Roofing Felt
Saturated Roofing Felt
78
N/A
N/A
1.4
2
13
955
330
5,510
20
12
22
Enough data were not available for primary manufacture of corrugated paper an
rollboard to estimate populations.
Frequency and Duration of Exposure. A full working year of 25
days/year and 8 hours/day can be assumed for the worker populations estimated
above.
Exposure Profile. Table A-l presents the exposure profile for
each paper product as determined from the raw monitoring data. We categorized
the jobs performed by each worker monitored into one of several job
categories. Geometric and arithmetic means were calculated for the data by
job category. This summary table includes the results for primary and
secondary manufacturing of asbestos paper products.
Since the monitoring data are aggregated for all paper products, the job
categories and exposures are assumed to be equivalent for all paper products.
- 236 -
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Table A-l. Exposure Profiles for Paper Products No Longer Manufactured in the U.S.*
8-Hour TWA (Exposure (f/cc)c
Product
Commercial Paper
Corrugated Paper
Rollboard
Flooring Felt
Unsaturated Roofing Felt
Saturated Roofing Felt
Job Category
Fiber Introduction
Processing
Other
Total
Fiber Introduction
Processing
Other
Total
Fiber Introduction
Processing
Other
Total
Fiber Introduction
Processing
Other
Total
Fiber Introduction
Processing
Other
Total
Fiber Introduction
Processing
Other
Total
Population
Distribution15
ax
581
34X
78/1,000 t
81
581
341
N/A
23Z
301
47X
N/A
21X
25X
541
1.4/1,000 t
461
191
351
2/1,000 t
OX
78X
22X
13/1,000 t
Pre-0.2
Geometric Mean
0.091 (6)
0.013 (23)
O.OS2 (5)
0.033
0.091 (6)
0.013 (23)
0.052 (5)
0.033
0.091 (6)
0.013 (23)
0.052 (5)
0.049
0.091 (6)
0.013 (23)
O.OS2 (5)
0.050
0.091 (6)
0.013 (23)
0.052 (5)
0.063
0.091 (6)
0.013 (23)
0.052 (5)
0.022
f/cc PEL
Arithmetic Mean
0.134
0.030
0.070
0.052
0.134
0.030
0.070
0.052
0.134
0.030
0.070
0.073
0.134
0.030
0.070
0.073
0.134
0.030
0.070
0.092
0.134
0.030
0.070
0.039
Post-0.2
Geometric Mean
0.079
0.013
0.052
0.032
0.079
0.013
0.052
0.032
0.079
0.013
0.052
0.047
0.079
0.013
0.052
0.04S
0.079
0.01
0.052
0.057
0.079
0.013
0.052
0.022
f/cc PEL"
Arithmetic Mean
0.094
0.030
0.070
0.049
0.094
0.030
0.070
0.049
0.094
0.030
0.070
0.064
0.094
0.030
0.070
0.065
0.094
0.030
0.070
0.073
0.094
0.030
0.070
0.039
Duration
(hr/day)*
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
6
8
§
8
Frequency
(days/yr)e
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
250
SECONDARY MANUFACTURING
Comnerclal Paper
Corrugated Paper
Rollboard
Flooring Felt
Unsaturated Roofing Felt
Saturated Roofing Felt
N/A
N/A
N/A
N/A
N/A
N/A
955/1,000 t
330/1,000 t
5,510/1,000 t
20/1,000 t
12/1,000 t
22/1,000 t
0.016 (26)
0.016 (26)
0.016 (26)
0.016 (26)
0.016 (26)
0.016 (26)
0.022
0.022
0.022
0.022
0.022
0.022
0.016
0.016
0.016
0.016
0.016
0.016
0.022
0.022
0.022
0.022
0.022
0.022
8
8
8
8
8
8
250
250
250
250
250
250
-------
Table A-l (Continued)
"This exposur. prof11. .ppli.s to comnerci.l paper, corrugated paper, rollboard. flooring felt, and roofing felt.
manufaetnMlB>0hiC*h """'"'M PoP"latl°n factor dependent upon the quantity of product manufactured (primary manufacturing) or mixture consumed (secondary
nr rniihn.trf TK A, » ?v J. , 5 """ ln 8ensitlvlty analysis. Adequate data are not available to estimate population factors for corrugated paper
(Lndrlc^n^ndXrl. iS tOt"1 ""**" °f m*"' "^^ int° 8Peci£lc -»ob Categories is based on the 1981 TSCA Section 8(a) data
.c and arithmetic means of the raw 8-hour TWA exposure data. (Exposures for leas than 8 hour, are converted to 8-hour
, .. -. - *8 8ucn- """"""ins zero exposure during periods when the worker is not handling asbestos.) Th. numb.r of data points is
in parentneses. Since the monitoring data is aggregated for all paper products, the exposure values for each Job category are assumed to be
in each JobPcatego^y " C°rrespondlns to tne total Population, are calculated as weighted averages based on the distribution of workers
'to^x.ctlv^ I^/^'n'r V?iUr* *" "lculated dl"«="y "o» the raw monitoring data. Each 8-hour TWA exposure value that i. above 0.2 f/cc is
to exactly 0.2 f/cc. Data that are already at or below this value remain unchanged.
8A full working year (8 hr/day, 250 daya/yr) la assumed.
Source.: ICP Market Survey 1986-1987, 1CF Exposure Survey 1986-1987. OSHA 1987. Bendrlck.on and Dorla 1983.
OJ
00
-------
In reality, however, sources indicated that exposure levels can vary widely
depending on the asbestos content of the product (OSHA 1986b).
The distribution of workers exposed into specific job categories is based
on the 1981 TSCA Section 8(a) data (Hendrickson and Doria 1983). For
secondary manufacturing of paper products, the total populations are not
disaggregated into job categories.
The primary manufacturing operation with the greatest potential for
causing asbestos exposure is fiber introduction. The fiber introduction
procedure in paper manufacturing involves the dumping of asbestos into a
beater or hydropulper. A local exhaust system with dust-collection equipment
is used to keep the processing area under negative pressure. The wet-mixing
of the fiber with paper stock, binder, and other ingredients controls the
release of airborne asbestos. Canopy hoods and exhausts that are utilized to
remove water vapor and heat from steam-heated rolls in the dry section also
aid in asbestos dust control. At the slitting, calendering and rewinding
stages, local exhaust ventilation, area hoods, and central exhaust collection
systems are the typical engineering controls.
All job categories comprising the manufacture of asbestos papers have been
able to achieve mean exposure levels below 0.2 f/cc. Out of all the
monitoring data, only a few samples are above the 0.2 f/cc level; all of these
data fall under the fiber introduction job category. Assuming that in these
few cases additional controls will be used to achieve 0.2 f/cc exposure
levels, the projected exposure under the new PEL will decrease slightly, as
shown in Table A-l.
No changes are projected for secondary manufacturing of paper products due
to the absence of any monitoring data greater than 0.2 f/cc.
- 239 -
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(2) Corrugated Asbestos Cenent Sheets
Product Description. Asbestos is used as a reinforcing
material in cement sheet products because of its high tensile strength,
flexibility, thermal resistance, chemical inertness, and large aspect ratio
(ratio of length to diameter). A cement sheet becomes strong, stiff, and
tough when asbestos fiber is added, resulting in a product that is -stable,
rigid, durable, noncombustible, and resistant to heat, weather, and corrosive
chemicals. Also, the asbestos cement sheet has sufficient wet strength to
enable it to be molded into complex shapes at the end of the production
process (Krusell and Cogley 1982).
Corrugated A/C sheet was used in the construction industry when the
additional strength afforded by corrugation was beneficial. Flat and
corrugated A/C sheets are used in somewhat different applications. Corrugate
A/C sheet is used mainly in industrial and agricultural applications, serving
as siding and roofing for factories, warehouses, and agricultural buildings.
It is also used as a lining for waterways and canal bulkheads, and for specia
applications in cooling towers (Krusell and Cogley 1982).
Process Description. A/C sheet, both corrugated and flat, is
manufactured by using a dry, a wet, or a wet-mechanical process. A/C sheet i
made from a mixture of Portland cement and asbestos fiber. An additional
fraction of finely ground inert filler and pigments is sometimes included. V'
general, sheets contain between 15 and 40 percent asbestos fiber. However,
for curing in short time periods, a general formulation of 12 to 25 percent
asbestos, 45 to 54 percent cement, and 30 to 40 percent silica is used
(Krusell and Cogley 1982).
Similar to the A/C pipe process, the raw materials are mixed with water t<
form a wet slurry of asbestos, cement, and silica. The slurry is then picked
up by a screen cylinder mold and transferred to a felt conveyor. The felt is
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then dewatered, passed to a mandrel, and wound to the desired thickness.
After achieving the desired thickness, a cut is made across the width of the
sheet. The sheet is manually peeled off the rotating mandrel onto a transfer
roll conveyor. The sheet is then cured, processed through embossing rollers
and trimming/cutting wheels, and finally corrugated.
There is no secondary manufacturing for corrugated A/C sheet.
Production and Employment. Currently, no workers are exposed
to asbestos during the manufacture of corrugated A/C sheet because this
product is no longer produced in the U.S. (ICF Market Survey 1986-1987).
However, based on historical data from the TSCA Section 8(a) submissions (EPA
1986b), the average number of workers who would be exposed per unit of
corrugated A/C sheet manufactured is one per 1000 squares (square - 100 ft^).
Duration and Frequency of Exposure. A full working year of 250
days/year and 8 hours/day can be assumed for the worker populations estimated
above.
Exposure Profile. Exposure levels for corrugated A/C sheet are
assumed to be the same as those for flat A/C sheet and A/C shingles. The
exposure levels for all job categories exhibited in Table A-2 are high, with
two out of the three job categories having exposure levels above 1.0 f/cc.
With the widespread use of engineering controls, the post-0.2 f/cc PEL
exposures are assumed to fall at or below the 0.2 f/cc level.
The distribution of workers exposed into specific job categories is based
on 1981 TSCA Section 8(a) data (Hendrickson and Doria 1983).
(3) Vinvl-Asbestos Floor Tile
Product Description. Floor tile was one of the largest
industrial uses of asbestos fiber in the past. Asbestos use in resilient
flooring includes viny1-asbestos "(V/A) floor tile and asbestos felt-backed
vinyl sheet flooring. V/A floor tile provides a hard, durable surface and is
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Table A-2. Exposure Profile for Corrugated Asbestos Cement Sheet — Primary Manufacture
NO
*>
fo
8-Hour TWA (Exnosura (f/cc)b
Job Category
Fiber Introduction
Processing
Other
Total
Population
Distribution*
13S
301
3ZI
1/1,000 sq
Pre-0.2
Geometric Mean
1.054 (7)
0.408 (6)
1.028 (6)
0.845
£/cc PEL
Arithmetic Mean
1.364
0.576
1.143
1.000
Post-0.2
Geometric Mean
0.200
0.166
0.200
0.190
f/cc PEtc
Arithmetic Mean
0.200
0.171
0.200
0.191
Duration
(hr/day)d
8
8
8
8
Frequency
(days/yr)d
250
250
250
250
'Based on historical data, a population factor dependant upon the quantity of product manufactured has been estimated for use
in sensitivity analysis. The distribution of the total population exposed into specific Job categories is bated on the 1981
TSCA Section 8(a) data (Hendxlckson and Dorla 1983).
These value* represent geometric and arithmetic means of the raw 8-hour IMA exposure data. Exposure* for leas than 8 hours
are converted to 8-hour THAs, assuming tsro exposure during period* when the worker 1* net handling asbestos. The number of
data point* is given in parentheses. The values corresponding to the total population* are calculated as weighted averages
baaed on the distribution of workers exposed in each job category.
°These post-0.2 f/cc PEL exposure values are calculated directly from the raw monitorins data. Each 8-hour THA exposure value
that is above 0.2 f/cc is reduced to exactly 0.2 f/cc. Data that are already at or below this value remain unchanged.
dA full working year (8 hr/day, 250 days/yr) is asauned.
Sources: OSHA 1987, ICF Market Survey 1986-1987, Hendrlckson and Doria 1983.
-------
suitable for most heavy traffic areas (e.g., supermarkets, department stores,
institutional/commercial settings) and radiant-heated floors (Wright 1984).
Asbestos felt-backed vinyl sheet flooring is produced as a floor cover for
general uses; the asbestos felt-backing that forms the underlaying of sheet
vinyl flooring is a paper product (refer to Section (1) above).
Beginning in the early 1980s, most major manufacturers of V/A floor tile
switched to substitutes for asbestos (Wright 1984). Since that time, asbestos
has been eliminated completely from V/A floor tile as there are currently no
domestic producers or importers of this product (ICF Market Survey 1986-1987).
V/A floor tile are made from polyvinyl chloride polymers or copolymers and
are usually produced in squares 12 inches by 12 inches; it is commonly
manufactured in thicknesses of 1/16, 3/32, and 1/8 of an inch (ICF Market
Survey 1986-1987).
Although V/A tile composition varies by type and manufacturer, typical
compositions are as follows (on a percentage weight basis):
• asbestos: 5-25 percent,
• binder: 15-20 percent,
• limestone: 53-73 percent,
• plasticizer: 5 percent,
• stabilizer: 1-2 percent, and
• pigment: 0.5-5 percent (ICF Market Survey 1986-1987, Wright
1984).
Asbestos fiber grades 5 through 7 are used to impact wet-strength and
dimensional stability (OSHA 1986b).
Process Description. The production of V/A floor tile involves
fiber introduction, mixing, melting, calendering, embossing, curing, and
finishing. Opened paper bags, or unopened polyethylene bags, of raw asbestos
are dumped into Banbury mixers, along with other dry ingredients (e.g.,
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binder, limestone, pigments). The mixers combine the ingredients into an
agglomerated homogenized plastic mass at a temperature of about 300°F (Wright
1984). This hot plastic mass encapsulates the asbestos fibers, thus reducing
the potential for exposure during later steps; the points with the most
potential for fiber release precede the mixing operation (Wright 1984). The
hot mix is dumped into a conveyor and passes under negative pressure to a
two-roll mill. The mill presses the plastic into a continuous slab, with an
initial thickness of 1 or 2 inches, which is fed through a series of
calendering rolls to achieve the desired final-product thickness.
Next, the warm sheet passes through an embosser which adds design feature
and texture to the surface. After partial cooling and waxing, the sheet is
cut into squares by a cutting press. The tiles are separated from the excess
scrap, inspected, and packaged. Scrap and rejected tiles are returned to the
mixer for recovery. V/A floor tile undergoes no secondary processing.
Specific job categories fit into the production process as follows. The
weighing and mixing of chemicals are accomplished in designated process areas
(NIOSH 1979c). A scale operator pulls a handle which gravity feeds a. tared
quantity of polyvinyl chloride resin to an empty hopper car. A bag of
asbestos is then added to the hopper with water (NIOSH 1979d). The hopper ca
is sent to the next station (scale operation) where it is positioned under a
hood. Any recycled product returned from the end of the line due to
unsatisfactory appearance is added to the hopper by a recycling process man.
At the next position, pigments from bulk samples are added to the hopper;
those pigments have been previously weighed by a pigment scale operator
(pigment operation). The hopper then travels to the Banbury station where th<
bucket is emptied into the Banbury mixer along with other ingredients; this
job is categorized as Banbury mixing. "Other" workers complete the processing
of the tile.
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Production and Employment-. Currently, no workers are exposed
to asbestos during the manufacture of V/A floor tile because this product is
no longer produced in the U.S. (ICF Market Survey 1986-1987). However, based
on historical data from the TSCA Section 8(a) submissions (EPA 1986b), the
average number of workers who would be exposed per unit of V/A floor tile
manufactured is 8.3 per million yd2.
Duration and Frequency of Exposure. A full working year of 250
days/year and 8 hours/day can be assumed for the worker populations'estimated
above.
Exposure Profile. Table A-3 presents the exposure profile for
V/A floor tile production as determined from the raw monitoring data. All job
categories achieve average fiber concentrations significantly less than 0.2
f/cc. The encapsulation of asbestos fibers, due to the formation of an
agglomerated plastic mass, controls exposures. The only jobs which have any
exposure values greater than the 0.2 f/cc level fall into the scale operation
and "other" categories; this is depicted by the average exposure reductions in
the post-0.2 f/cc PEL values from the pre-0.2 f/cc PEL values. The projected
post-0.2 f/cc PEL exposures are based on the assumption that all raw data
points greater than 0.2 f/cc are adjusted to exactly 0.2 f/cc. This reduction
may occur via the utilization of engineering controls or the use of
respirators. Dust control is commonly achieved through enclosure of processes
and conveying equipment, exhaust ventilation, and good housekeeping and work
practice. Local exhaust ventilation is provided at stations such as fiber
introduction and cutting (OSHA 1986a). Mottling granulation and scrap
grinding may be isolated in enclosed rooms. More specifically, slot exhaust
ventilation is used during Banbury mixing and pigment operations, open duct
exhaust ventilation is used during recycling processes, and canopy exhaust
ventilation is used during scale operations (NIOSH 1979c, NIOSH 1979d).
- 245 -
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Table A-3. Exposure Profile for V/A Floor Tile -- Primary Manufacture
Job Category
Population
Distribution"
8-Hour TWA (Exposure (f/cc)
Pre-0.2 f/cc PEL
Post-0.2 f/ce PELC
Duration Frequency
Geometric Mean Arithmetic Mean Geometric Mean Arithmetic Mean (hr/day) (daya/yr)
Scale Operation
Banbury Mixing
Pigment Operation
Recycling Process
Other
Total
231
23X
81
7X
121
8.3/mll sq yd
0.029 (28)
0.028 (9)
0.005 (6)
0.048 (6)
0.047 (10)
0.095
0.039
0.020
0.055
0.094
0.073
0.200
0.028
0.005
0.048
0.046
0.034
0.068
0.039
0.020
0.055
0.086
0.064
8
8
8
8
I
250
250
250
250
250
250
*Ba«ed on historical data, a population factor dependent upon the quantity of product manufactured hai been estimated for use
In sensitivity analysis. The distribution of the total population exposed Into specific job categories is based on the 1981
TSCA Section 8(a) data (Hendrlckson and Dor la 1983).
These values represent geometric and arithmetic means of the raw 8-hour THA exposure data. Exposures for less than 8 hours
are converted to 8-hour THAs, assuming zero exposure during periods when the worker is not handling asbestos. The number of
data points is given in parentheses. The values corresponding to the total populations are calculated as weighted averages
based on the distribution of workers exposed in each Job category.
°These post-0.2 f/cc PEL exposure values are calculated directly from the raw monitoring data. Each 8-hour THA exposure
value that is above 0.2 f/cc is reduced to exactly 0.2 f/cc. Data that are already at or below this value remain unchanged.
dA full working year (B hr/day. 250 days/yr) is assumed.
Sources: OSHA 1987, ICF Market Survey 1986-1987, NIOSH 1979c, NIOSH 1979d, Bendrickson and Dorla 1983.
-------
b. Construction Industry Exposure
Historically, construction materials and products containing asbestos
fibers have included vinyl-asbestos floor tiles and asbestos felt-backed sheet
vinyl flooring. Since the early 1970s, however, the overall demand for these
types of products has declined due to the availability of adequate
substitutes, and the increased regulatory requirements and restrictions. This
declining demand has continued through the present and, as a result, these
products are no longer produced or sold in the U.S. (ICF Market Survey
1986-1987). Exposure to asbestos in the construction industry would occur
during installation and removal of these products. (Exposures during
construction of built-up roofing using roofing felts are covered in Chapter
II, Section E.)
(1) Exposure Settings and Operations
Vinyl-asbestos floor tiles could be installed either by
professional floor installers or homeowners, while asbestos felt-backed sheet
vinyl flooring is usually laid down only by professionals due to the
difficulty involved in creating a perfect fit with the one-piece sheet
(Anderson 1982). The installation of floor covering is typically begun in the
center of a room and proceeds towards the walls. For V/A floor tile, tile
adhesive is applied over one section of the floor at a time, if the tiles are
not prebacked with adhesive, and full tiles are pressed in place. Once all
full tiles are applied, the perimeter and partial pieces are measured and cut
out. Tile pieces are hand cut either by scoring the tile (cutting partially
through) and snapping it, or by simply cutting entirely through the tile in
one operation (Anderson 1982). All cutting occurs in the room being tiled.
Cutting tools for installation include commercial tile cutters, utility
knives, scissors, and razor knives (Anderson 1982).
- 247 -
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Many installers consider subfloor preparation to be the most difficult and
time consuming part of flooring installation (Anderson 1982). This highly
important activity commonly involves sanding and dry scraping, although
sanding in often explicitly warned against by the manufacturer. Subfloor
preparation by sanding involves the greatest potential for asbestos exposure
if the existing subfloor is covered with an asbestos-containing floor product
The majority of installers try to avoid sanding and either remove existir
flooring using flat-bladed putty knives or cover the floor with plywood,
fiberboard, or masonite (Anderson 1982). Other tools utilized for removal of
old flooring (particularly vinyl*asbestos floor tile) include hammers,
chisels, scrapers, and stripping machines. By far, the major release of
asbestos to the environment from flooring occurs at replacement time when old
flooring is removed (Syracuse Research Corp. 1978). Service life for asbesto;
floorings depends upon the severity of use and may, thus, vary from 10 to 30
years (Syracuse Research Corp. 1978).
The installation of asbestos felt-backed sheet vinyl flooring involves
adhesion techniques similar to those described for V/A tile. Gluing
techniques for sheet flooring vary in three basic ways: fully pasted,
perimeter pasted, and "put down quick" (PDQ) technique (Anderson 1982).
A fully pasted floor, whereby the entire felt backing is glued, takes the
most time to install, but will last the longest. When only the flooring
perimeter is glued, the installation is quicker and less expensive; this
technique is mostly used on concrete subfloors. A PDQ installation, in which
the flooring is layed without any glue, is more common to flooring which is
solely vinyl than it is to the more expensive asbestos felt-backed product
(Anderson 1982).
Sheet vinyl flooring must be cut to shape and size; a template is widely
used for this process. The template, often composed of narrow strips of
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asbestos-containing felt, is cut to match the exact perimeter details of the
room. These details are then transferred onto the sheet vinyl product.
Utility and razor knives are used for cutting the template as well as for
cutting the actual flooring. Preparation and installation of sheet vinyl
flooring involves minor mechanical disturbance to the product, minimizing the
potential for airborne asbestos fiber release.
The standard procedure in the removal of asbestos felt-backed vinyl
flooring is to "strip" the floor. This operation involves removing the top
two layers of sheeting (wear and foam) and splitting the bottom asbestos
flooring felt layer in half, along the horizontal plane (Anderson 1982). This
procedure is relatively easy if the subfloor covering is glued over its entire
area, since the felt will split when pulled.
During flooring felt removal, the covering is cut into strips
approximately 0.46 meters (1.5 feet) wide and each strip is pulled up and away
from the subfloor. This separation process leaves half of the felt in place
and provides a uniform subfloor for the new flooring product; the cutting and
separation may have a high fiber release potential (Anderson 1982). One
manufacturer recommends that the exposed felt be vacuumed immediately after
each strip is removed to collect loose asbestos fiber-containing dirt
(Anderson 1982).
If the asbestos felt-backed sheet vinyl flooring is not totally surface
glued, then stripping will remove the entire covering, leaving only split
asbestos felt around the perimeter (assuming the flooring had only been pasted
along its perimeter). The recommended practice for this process is to wet the
felt before scraping it up; it can also be feathered to provide a smooth felt
interface, however this involves the sanding of the felt, with higher
potential exposures. Another scenario can arise if the existing sheet
flooring is intact and relatively smooth. In this case the top layer can be
- 249 -
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used as Che subfloor after being rough sanded Co provide for better adhesion;
Chis sanding will discurb only Che wear layer of Che sheec flooring and not
Che asbestos felt (Anderson 1982).
(2) Current Pre-0.2 f/cc PEL Exposures .
Various studies have been performed on construction-related
industries to determine exposure Co asbestos produces during installation and
removal.
Alchough Chore are a large number of potential uses and activities
involved in the installation and renoval of asbestos flooring products, there
is only a limited amount of data concerning exposure to asbestos fibers during
construction projects. ICF has utilized three sources of exposure data in
determining average values for the installation and removal of V/A floor tile
and asbestos flooring felt (Canadian A.I.C. 1979. Murphy 1971, Jenkins 1985).
The one study containing information on flooring felt (Canadian A.I.C. 1979)
refers to the product as sheet vinyl flooring. As discussed earlier, the
asbestos flooring felt (or sheet backing) forms the underlayment of sheet
vinyl flooring. Alchough the felt is manufactured separately from the sheec
vinyl flooring, it muse be considered together with sheec vinyl flooring for
purposes of exposure assessment, since the felt backing is typically not used
alone. Table A-4 summarizes the pre-0.2 f/cc PEL asbestos exposure levels for
both V/A floor tile and sheet flooring.
Except for those samples from the Jenkins (1985) study, all samples were
analyzed with phase-contrast microscopy. The value reported in this study
(Jenkins 1985), comprised of condensed data from 40 asbestos fiber samples, is
based on transmission electron microscopy (TEM) testing. Because the TEM
detects all fiber sizes, both greater than and less than 5 microns in length,
the value is adjusted so as to represent an equivalent value that only
consists of fibers greater than 5 microns in length. The percentage of fibers
- 250 -
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Table A-4. Exposure to Asbestos Floor Products in the
Construction Industry Under Pre-0.2 f/cc PEL
8-Hour TWA Short-Term TWA
Exposure Level* Exposure Level3
(f/cc) (f/cc)
Product
V/A Floor Tile
V/A Floor Tile
Asbestos Flooring
Felt
Asbestos Flooring
Felt
Activity
Installation
Removal
Installation
Removal
Geometric
Mean
0.017b
0.011C
0.016d
0.032d
Arithmetic Geometric
Mean Mean
0.026 0.049b
0.012 0.018C
0.036 0.016d
0.081 0.032d
Arithmetic
Mean
C.425
0.029
0.036
0.081
aExposure estimates are geometric and arithmetic means of all of the available
exposure data for each product and operation.
bCanadian A.I.C. 1979, Murphy 1971.
cCanadian A.I.C. 1979, Jenkins 1985.
dCanadian A.I.C. 1979.
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greater than 5 microns in length is determined by Jenkins (1985) to be 27.5
percent of the total TEM count; thus, 27.5 percent of the value provided
(0.2382 f/cc) is utilized for the geometric and arithmetic mean values.
Both geometric and arithmetic means of the raw exposured data are
presented in Table A-4. For the purpose of these calculations, all 8-hour TWA
data points that have a value of zero (i.e., 0.0 f/cc) are assumed to be
equivalent to 0.001 f/cc. A zero count implies that the count was too low for
any fibers to be seen in the counting fields; these "non-detectable" levels
are consistent with very low, but rarely zero, concentrations of airborne
fibers. The low value (0.001 f/cc) is assumed to approximate the limit of
detection for the Canadian A.I.C. (1979) study, which reported very low values
(e.g., 0.007 f/cc) for other samples.
Table A-4 presents two sets of data, 8-hour TWA and short-term TWA
exposure levels. The effective duration of exposure is 8 hours/day in all
cases; and for two out of four product-activity average values, the 8-hour TW
equals the short-term TWA. For these two cases, both sets of values were
provided in the study results (Canadian A.I.C. 1979). But for the other two
cases, where data are supplied by two other sources (Jenkins 1985, Murphy
1971) , some exposure data (assumed to be sampled for less than 8 hours/day)
are converted to 8-hour TWAs. The 8-hour TWA was calculated from the TWA for
the time sampled as follows:
8-Hour TWA - Sampling Time (minutes) x ^ fn period Qf ^ ^^
480 Minutes
The worker is assumed to have no exposure for the remainder of the work day
(i.e., when not handling asbestos).
Most V/A floor tiles are installed by simply applying adhesive, or
removing the protective cover layer of tiles prebacked with adhesive, and
pressing the tiles in place. Only perimeter pieces are typically cut. Both
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tasks, applying adhesive/pressing tiles in place and cutting, result in
minimal asbestos fiber release as revealed by the low exposure level in
Table A-4. The low energy input associated with the use of cutting tools
(mostly hand tools) and the binding properties of the tile matrix minimize
fiber release during installation (Anderson 1982).
Although a significant amount of asbestos fiber can be released during
removal of V/A tile using conventional tile removal methods (Jenkins 1985),
Table A-4 reveals a low exposure level. Apparently, good removal practices
were followed during the sampling. Fiber control methods such as damp
removal, isolation of areas by plasticizing, and use of respirators should be
used for tile removal. It is also important to avoid sanding, whenever it is
economically or practicably possible, as is the case with the removal
operations sampled (Canadian A.I.C. 1979, Jenkins 1985, Anderson 1982).
Potential exposure levels during the installation of asbestos felt-backed
sheet vinyl flooring are also low. There are only minor mechanical
disturbances to the product, minimizing the potential for airborne asbestos
fiber release. The only action during installation that disturbs the asbestos
felt layer of the flooring is cutting, an activity that is short in duration
(5 to 20 minutes) and not energy intensive (Anderson 1982).
As with removal of all asbestos floor products, the industry recommends
the use of wet scraping methods for the removal of sheet vinyl flooring.
Results of the study employed (Canadian A.I.C. 1979) in determining the values
in Table A-4, show that wet scraping methods result in very low concentrations
of airborne asbestos fiber. All data points used to calculate the geometric
and arithmetic means were sampled during removal by the proper wet methods.
According to the Resilient Floor Covering Institute, dry scraping is not a
recommended work practice (Anderson 1982).
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Concentrations for the two sheet vinyl flooring activities are somewhat
higher than those for V/A floor tile. The higher levels are expected because
the felt backing contains a much higher percentage of asbestos (85 percent)
than the tile product (8 to 30 percent) and is not as structurally cohesive as
the tile (Anderson 1982).
(3) Projected Post-0.2 f/cc PEL Exposures
Reduction of the PEL for asbestos from 2 f/cc to 0.2 f/cc means
that increased worker protection is required in installation and especially
removal of asbestos flooring. In the construction industry, many companies
are small operators who cannot afford extensive protective gear or certain
sophisticated power tools with dust collection systems. However, for these
product sectors, extensive change in procedures or controls is barely needed.
As shown in Table A-5, almost all of the projected exposure levels are
equivalent to the pre-0.2 f/cc PEL values. This is because, of all the raw
8-hour TWA data, only one data point is greater than 0.2 f/cc (Canadian A.I.C.
1979); thus, only projections for flooring felt removal differ from the
pre-0.2 f/cc PEL values (i.e., both 8-hour and short-term TWAs differ).
The projected exposures presented in Table A-5 are based on the assumption
that all raw data points greater than 0.2 f/cc (in this case there is only one
data point) are adjusted to exactly 0.2 f/cc. This reduction may occur via
the increased utilization of engineering controls (e.g., tool shrouding), the
total abandonment of sanding and dry scraping operations, or the use of
respirators.
(4) Population Exposed
Workers in the construction industry often work with a variety of
materials, depending on the needs of the purchaser. However a determination
can be made of the equivalent number of workers who would work full-time (8
hours/day and 250 days/year) exclusively with asbestos products. This number,
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Table A-5. Exposure to Asbestos Floor Products in the
Construction Industry Under Post-0.2 f/cc PEL
8-Hour TWA Short-Term TWA
Exposure Level3 Exposure Levela
(f/cc) (f/cc)
Product Activity
V/A Floor Tile Installation
V/A Floor Tile Removal
Asbestos Flooring Installation
Felt
Asbestos Flooring Removal
Felt
Geometric
Mean
0.017b
0.011b
0.016b
0.029
Arithmetic Geometric
Mean Mean
0.026b 0.049b
0.012b 0.018b
0.036b 0.016b
0.051 0.029
Arithmetic
Mean
0.425b
0.029b
0.036b
0.051
Projections are calculated assuming that all 8-hour TWA raw data values
originally >0.2 f/cc would be reduced to this limit, and new geometric and
arithmetic means are calculated.
bNo change from the pre-0.2 f/cc PEL exposure.
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the full-time equivalent (FTE) population, is based on crew size,
productivity, and total production plus imports of the asbestos product.
Since vinyl-asbestos floor tiles and flooring felt are no longer manufactured,
imported, or used in the U.S., the FTE population cannot be calculated.
However, the factors which allow calculation of FTEs are provided. These
factors provide FTE population per unit of product installed or removed. In
the construction industry, crew sizes can be estimated based on Means Man-Houi
Standards (Means 1983).
A typical crew size for installation of V/A floor tile (i.e., categorized
as resilient flooring) is composed of a single tile layer. Daily output (for
an 8 hour work day) is estimated at 520 square feet per day (Means 1983) .
Therefore, the population factor for installation of V/A floor tile is 0.008
person-years/I,000 ft2. Anderson (1982) states that the installation of V/A
tile in a standard 9 by 12 foot (2.7 by 3.6 meter) room would take one profes
sional installer from 2 to 4 hours (i.e., 0.009-0.018 person-years/I,000\ft2)
The time spent in cutting the tile (usually only the perimeter pieces are cut
amounts to only about 10 minutes for a standard room (Anderson 1982); this
short duration is the period of time with the highest potential for asbestos
fiber release.
Means (1983) estimates that a single installer (typical crew size) can la>
down between 325 and 650 square feet of vinyl sheet flooring (with backing)
per day (i.e., 0.006-0.012 person-years per 1,000 ft2). This wide range is,
apparently, due to differences in the width of the vinyl roll (1.8, 2.7, 3.6,
or 4.5 meters), the way in which the flooring is glued, and whether or not a
pattern is used (Anderson 1982). The installation of asbestos felt-backed
sheet vinyl flooring in a standard 9 by 12 foot room is estimated to take
between 1.5 and 6 hours by Anderson (1982), depending on the roll width,
gluing technique, and pattern usage. Based on this source, the population
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factor for installation of asbestos felt-backed sheet vinyl flooring is
between 0.007 and 0.028 person-years/I,000 ft2. The narrower the flooring
width, the greater the installation time since the patterns of adjoining
sections must be matched (Anderson 1982). Installation time also depends on
the complexity of the perimeter details and the skill of the installer
(Anderson 1982). As with tile installation, the cutting activity is short in
duration (5 to 20 minutes for the standard size room), taking only a fraction
of the total installation time.
The time it takes to remove asbestos flooring products (i.e., either V/A
tile or vinyl sheet flooring) is approximately 4 to 8 hours for a standard 9
by 12 foot room (Anderson 1982); this figure varies considerably depending on
difficulties encountered in removing old tile or sheeting. Subfloor
preparation (i.e., old flooring removal) is considered by many workers to be
the most time consuming part of a flooring construction activities. The
productivity estimate (4 to 8 hours) is assumed to be based on a crew of only
one worker. Therefore, the population factor for removal of V/A floor tile or
sheet vinyl flooring is between 0.018 and 0.037 person-years/I,000 ft2.
(5) Frequency and Duration of Exposure
In the construction industry, exposure duration and frequency are
effectively 8 hours/day and 250 days/year because full-time equivalent
populations are being used in this analysis. Conceptually, this is a
measurement of the total person-hours of exposure involved (much as
construction jobs require a certain number of man-hours to. do the work) and
not the actual number of workers who at some time might install or remove
asbestos-containing materials.
2. Air Releases
As stated in Chapter III, the technical data base from which emissions
estimates are derived contains significant data gaps as well as other sources
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of uncertainty that require the use of simplifying assumptions. Therefore,
the results of this analysis represent estimates given the available data and
should be used cautiously. The emission estimates are by no means absolute
values.
In this section, emission estimates are presented for: (1) primary and
secondary manufacture of commercial paper, corrugated paper, rollboard,
flooring felt, roofing felt (unsaturated and unsaturated), corrugated asbesto
cement sheet, and vinyl-asbestos floor tile which are all products no longer
manufactured in the U.S.; and (2) construction usage of vinyl-asbestos floor
tile and asbestos felt-backed sheet vinyl flooring which are no longer used in
the U.S. Since these products are no longer manufactured in the U.S.,
information on the location of emission sources; stack dimensions; exhaust gas
flow rate, temperature, and velocity are not relevant.
a. Primary and Secondary Kanufaeturing Sources
The methodology used to calculate asbestos emissions from primary and
secondary manufacturing sources is discussed in detail in Chapter III. A
steady state release rate is estimated over an entire year for primary and
secondary manufacturing; a full year is 8,760 hours per year (365 days/year
and 24 hours/day). The quantity of asbestos fiber or mixture consumed for
each product category is derived from the Section 8(a) data (EPA 1986b). The
collection efficiency of the control device is estimated to be 99.67 percent
for paper products, and 99.95 percent for V/A floor tile and corrugated A/C
sheet.
The quantity of asbestos fibers collected by the control device is equal
to the total quantity of waste collected times the asbestos content in the
waste. The quantity of waste collected per unit of production is derived by
calculating the ratio of waste collected by the control device in 1981 (EPA
1986b) to asbestos fiber consumed in 1981 (EPA 1986b). To determine the
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quantity of waste collected, this ratio would be multiplied by the amount of
fiber consumed. Since these products are no longer manufactured, only the
ratio of waste generation to fiber consumption is presented. The average
asbestos content in the waste is also available from 8(a) data (EPA 1986b).
For secondary manufacturing, the factor used to calculate the total waste
collected in the control device is presented as waste collected per unit of
asbestos mixture consumed; these ratios are also obtained from the TSCA 8(a)
data (EPA 1986b).
Asbestos air emissions from primary and secondary manufacturing sources
are estimated for asbestos paper products (commercial paper, corrugated paper,
rollboard, flooring felt, and roofing felt), vinyl-asbestos floor tile, and
corrugated A/C sheet. Table A-6 presents asbestos emissions from primary
manufacturing sources, and Table A-7 presents emissions from secondary
manufacturing sources. There is no secondary manufacturing of V/A floor tile.
b. Construction Sources
The asbestos-related activities performed in the construction trade
include installation and removal of asbestos material. The construction
industry is different than general industry in that the worksites are
temporary in nature and seasonal. The points of emissions cannot be well
defined due to the nature and large number of work settings. For indoor jobs,
asbestos is emitted through a number of openings such as windows, doors, and
cracks. For outdoor jobs, airborne asbestos can be dispersed in any or all
directions, depending on the wind vectors. In other words, the release
configuration from these sources is unconfined with multiple exits. All of
these factors contribute to the difficulty of making an accurate assessment of
asbestos air emissions from these sources. The methodology used to estimate
emissions from indoor and outdoor construction activities is presented in
Chapter III, Section C.
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Table A-6. Asbestos Emission* from Primary Manufacturing Sources
for Products No Longer Manufactured in the U.S.
N)
ON
O
Asbestos Product/Mixture
Conner cial Paper
RoUboard
Unsaturated Roofing Felt
Saturated Roofing Felt
Flooring Felt
Corrugated Paper
Vinyl Asbestos Floor Tile
Asbestos Cement Sheet,
Corrugated
TSCA
Identification
Number
01
02
07
08
09
10
12
16
1981 Asbestos
Consumption*
(short tons)
1,038
213*
15.434
5,709
105, 7 821
54
29.6511
1,106
Total
Quantity
of Baghouae
Haste (198l)b
(short tons)
U2d
13*
44«
16h
8,838J
7d
3*2-*
11*
Percent
of Asbestos
in Waste0
(X)
80. Od
83.0*
62.5
82. 5h
57.3
80. Od
7.9
11. Oh
Emission Rate
(g/sec)
1.08E-2
1.03E-3
3.46E-3
1.26E-3
4.83E-1
5.34E-4
3.89E-4
1.77E-4
Emission Rate
Per Pound of
Fiber Consumed
(g/sec/lb)
5.22E-9
2.41E-9
1.12E-10
1.10E-10
2.28E-9
4.94E-9
6.56E-12
8.02E-11
*EPA 1986b (Table 3). This is the total quantity of asbestos consumed per product category in 1981. The quantities were
reported in ranges as "minimum" and "maximum" quantities; the average value was calculated and reported in this table.
1986b (Table 15). This is the total quantity of baghouse fines, dry waste. It does not contain 100 percent asbestos fiber.
CEPA 1986b (Table 14). Assumed the percent of asbestos in baghouae waste is equal to the percent of asbestos in the total waste.
'There is no data available for this product category. It is ana of the "missing categories" in the Section 8(a) data, EPA 1986.
Assumed that the quantity of baghouae waste end the percent of asbestos in waste are relatively similar to electrical paper
category, and thus the quantity of baghouse waste was adjusted accordingly based on the total quantity of asbestos consumed.
'This is the quantity of asbestos consumed in 1979. Asbestos rollboard was not produced in 1980 or 1981.
See footnote (d). Calculations were made based on reported values for asbestos millboard.
'Baghouse waste was not reported. Assumed baghouse waste is half of the total waste reported In EPA 1986b .(Table 15).
^>ee footnote (d). Calculations were made based on reported values for unsaturated roofing felt.
1This is the quantity of asbestos fiber consumed in 1981 obtained from EPA 1986b (Table 3). A single value rather than a range
is reported.
''Baghouse waste (dry) was not reported. Assumed baghouse fines dry is equal to baghouse fines wet reported in EPA 1986b
(Table 15).
See footnote (d). Calculations were made based on reported values for asbestos cement shingle.
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Table A-7. Asbestos Emissions from Secondary Manufacturing Sourcaa
for Products No Longer Manufactured In the U.S.
ro
cr»
Asbestos Mixture/
Product (ID 41)
Ccmnercial Paper (01)
Rollboard (02)
Unaaturated Roofing Felt (07)
Saturated Roofing Felt (08)
Flooring Felt (09)
Corrugated Paper (10)
A/C Sheet. Corrugated (16)
1981 Total Asbaatoa
Mixture Consumption*
508 tons
28.5 tons
27,714 tons
3,457.5 tons
98,420 tons
14. 5 tons
344 squares
(1 square ~ 100 sq ft)
Total
Quantity
of Baghouse
Waste (1981)b
(short tons)
17
1.6
291
150
3,413
0.3
3.4d
Percent
of Asbestos
in Waste0
(I)
46.6
55.3
54.7
54.7
39.0
£0.7
30.0
Emission Rate
(g/sec)
7.57E-3
8.45E-5
1.52E-2
7.B4E-3
1.27E-1
1.73E-3
1.47E-5
Emission Rate
Per Found of
Mixture Consumed
(g/aec/lb)
1.49E-5
2.96E-6
5.49E-7
2.27E-6
1.29E-6
1.19E-6
4.27E-B*
"EPA 1986b (Table 8).
EPA 1986b (Table 17). Baghouse fines dry or one-half of the total waste adjusted by the percentage of the consumed
materials accounted for by the product under investigation. Haste data are provided by mixture code* (101-220) rather
that product codes (1-34), and several products are identified as feed materials for the mixture classifications.
CEPA 1986b (Table 16).
Estimated based on values reported for A/C sheet, flat.
*Thls la the emission rate of asbestos per one square of corrugated A/C sheet rather than per Ib pof corrugated A/C
sheet.
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Asbestos air emissions from construction sources are presented in
Table A-8, using both the geometric and arithmetic mean, short-term asbestos
concentrations. The two types of activities analyzed for V/A floor tile and
asbestos flooring felt are installation and removal. (Asbestos air releases
from roofing felt construction activities are estimated in Chapter III,
Section C.) Since all of the construction activities for V/A floor tile and
flooring felt are performed indoors, a work volume of 9,000 cu ft is assumed
with one air change per hour.
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Table A-B. Asbestos Emissions from Construction Activities Using Products
Ho Longer Used in the U.S.
NJ
Short Term TWA
Asbestos Concentration
(f/cc)a
Construction Activity
V/A Floor Tile Installation
V/A Floor Tile Removal
Asbestos Flooring Felt Installation
Asbestos Flooring Felt Removal
Geometric
Mean
0.049
0.01B
0.016
0.029
Arithmetic
Mean
0.425
0.029
0.036
O.OS1
Asbestos Emission Rate
((l/»*c>
Work Area
Volume
(ft3)
9,000
9,000
9,000
9,000
Mumber of
Air Changes
Per Hour
1
1
1
1
Using
Geometric
Mean
1.16E-7
4.25E-8
3.78E-6
6.8AE-8
Using
Arithmetic
Mean
l.OOE-6
6.84E-8
8.49E-8
1.20E-7
Person-Years
Per 1,000 sq ft
of Product
Consumed
0.011
0.028
0.013
0.028
Asbestos Emission Ratt
(*/so ft)
Using
Geometric
Mean
9.2E-6
8.6E-6
3.5E-6
1.4E-5
Using
Arithmetic
Mean
7.9E-5
1.4E-5
8.0E-6
2.4E-5
*Refer to Section l.b above.
bAverage value la used. Refer to Section l.b above.
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