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IC 9125 
 
 Bureau of Mines Information Circular/1987 
 
 Respirable Dust Levels in Coal, Metal, 
 and Nonmetal Mines 
 
 By W. F. Watts, Jr., and D. R. Parker 
 
 UNITED STATES DEPARTMENT OF THE INTERIOR 
 

 
Information Circular 9125 
 
 Respirable Dust Levels in Coal, Metal, 
 and Nonmetal Mines 
 
 By W. F. Watts, Jr., and D. R. Parker 
 
 UNITED STATES DEPARTMENT OF THE INTERIOR 
 Donald Paul Hodel, Secretary 
 
 BUREAU OF MINES 
 Robert C. Horton, Director 
 

 Library of Congress Cataloging in Publication Data: 
 
 Watts, W. F. (Winthrop F. Jr) 
 
 Respirable dust levels in coal, metal, and nonmetal mines. 
 
 (Information circular ; 9125) 
 
 Bibliography: p. 18. 
 
 Supt. of Docs, no.: I 28.27: 9125. 
 
 1. Mine dusts- United States- Standards. 2. Coal mines and mining- United States- Dust 
 control -Standards. I. Parker, D. R. (Douglas R.) II. Title. III. Series: Information circular 
 (United States. Bureau of Mines); 9125. 
 
 4^295JI4^" [TN312] 622 s [363.1'19622] 86-600380 
 
CONTENTS 
 
 Page 
 
 Abstract 1 
 
 Introduction • 
 
 MIDAS metal and nonmetal subsystem 
 
 Regulatory requirements 
 
 Data description 2 
 
 Software ••• 3 
 
 MIDAS coal subsystem 4 
 
 Regulatory requirements 4 
 
 Data description 4 
 
 Software 5 
 
 Respirable dust analysis 5 
 
 Metal and nonmetal « 5 
 
 Exposures by mine type and occupation 6 
 
 Effect of changing the RQ standard 8 
 
 Coal 9 
 
 Summary and conclusions 17 
 
 References . 18 
 
 Appendix. — MSHA sampling codes, descriptors, and selected data 19 
 
 ILLUSTRATION 
 
 1. Logarithmic probability plots of longwall, continuous ripper, and auger 
 
 samples grouped by designated occupation and nondesignated occupation... 13 
 
 TABLES 
 
 1. Contaminants most frequently sampled in metal and nonmetal mines 3 
 
 2. Yearly statistics for RQ 6 
 
 3. RQ exposures by mine type for 1974-79 and 1980-84 7 
 
 4. RQ exposures by metal and nonmetal occupation for 1974-79 and 1980-84.... 8 
 
 5. Quartz statistics for selected commodities 9 
 
 6. Effect of changing the RQ TLV 10 
 
 7. Yearly trends in respirable dust exposure for samples collected in under- 
 
 ground coal mines 11 
 
 8. 1984 coal dust data by underground mining method 11 
 
 9. Differences between DO and NDO samples for three mining methods 12 
 
 10. Average number of samples exceeding 2.0 mg/nr 5 for 1981-84 and average 
 
 number of mines with samples exceeding 2.0-mg/ra- 5 standard 14 
 
 11. 1984 coal mine dust data for underground and surface occupations 15 
 
 12. Trends in exposure for five underground coal mine occupations 16 
 
 A-l. Metal and nonmetal occupation codes 20 
 
 A-2. Metal and nonmetal location codes 20 
 
 A-3. Metal and nonmetal SIC codes 21 
 
 A-4. Occupation codes most frequently used in 1984 by MSHA coal mine 
 
 inspectors 22 
 
 A-5. MSHA coal mine codes for mine type 22 
 
 A-6. MSHA coal mine codes for sample type 23 
 
 A-7. MSHA coal mine codes for mining method 23 
 
 A-8. Percentage of metal and nonmetal miners wearing respirators 23 
 
 i 
 

 UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 
 
 L/min 
 
 liter per minute mm 
 
 millimeter 
 
 mg/m- 5 
 
 milligram per cubic meter pet 
 
 percent 
 
 yg/m 3 
 
 microgram per cubic meter yr 
 
 year 
 
RESPIRABLE DUST LEVELS IN COAL, METAL, AND NONMETAL MINES 
 
 By W. F. Watts, Jr., 1 and D. R. Parker 2 
 
 ABSTRACT 
 
 In 1980 the Bureau of Mines developed the Mine Inspection Data Analy- 
 sis System (MIDAS). MIDAS is a computerized, industrial hygiene data 
 base capable of statistically analyzing environmental data collected in 
 coal and noncoal mines and mills by Mine Safety and Health Administra- 
 tion (MSHA) inspectors or mine operators. The objectives of this report 
 are to describe the current contents of MIDAS, to report analyses of 
 coal and noncoal mine respirable dust samples collected by MSHA inspec- 
 tors and to evaluate the proposed change in the metal and nonmetal 
 respirable dust standard from a formula based upon the percentage of 
 quartz identified in the sample to 100 ug/m 3 of respirable quartz. 
 
 Based on samples collected by MSHA inspectors, changing the noncoal 
 respirable dust standard would result in 4 pet fewer samples with dust 
 concentrations exceeding the standard. Analysis of respirable coal dust 
 data collected by MSHA inspectors showed that mines with longwall plows 
 or shears had the highest geometric mean concentrations (1.64 and 1.29 
 mg/ra 3 , respectively). Mine operations using continuous rippers out- 
 numbered longwall mine operations about 10 to 1 and had a geometric mean 
 concentration of 0.66 mg/m 3 . 
 
 industrial hygienist, Twin Cities Research Center, Bureau of Mines, Minneapolis, 
 MN. 
 
 2 Mine safety and health specialist, Mine Safety and Health Administration, U.S. 
 Department of Labor, Arlington, VA. 
 
INTRODUCTION 
 
 In 1980 the National Academy of Sci- 
 ences stated that because of insufficient 
 respirable dust measurements and the pau- 
 city of reliable information on the inci- 
 dence of silicosis, the most critical 
 research need in noncoal mining was a 
 definition of the extent of the health 
 problem associated with silica exposures 
 in noncoal miners. It was further stated 
 that the adequacy of the current standard 
 could not be evaluated when the magnitude 
 of exposures remains unknown (1_).3 
 
 The Bureau of Mines responded to this 
 report by establishing the Mine Inspec- 
 tion Data Analysis System (MIDAS) as a 
 part of the respirable dust research 
 program. MIDAS is a computerized, indus- 
 trial hygiene data base developed by 
 the Bureau with the assistance of the 
 Mine Safety and Health Administration 
 (MSHA). It is available, on-line, via 
 the Bureau's telecommunications network 
 to Bureau, MSHA, and National Institute 
 of Occupational Safety and Health (NIOSH) 
 personnel involved in mining research. 
 Since its inception, MIDAS has provided 
 information on the magnitude of res- 
 pirable dust levels in noncoal mines, 
 which is used to prioritize problems, 
 determine trends in exposure, and to 
 evaluate standards. In 1980 MIDAS con- 
 tained only environmental industrial 
 hygiene data collected from metal and 
 
 nonmetal mines and mills by MSHA inspec- 
 tors. These samples are collected to 
 determine whether or not the mine or 
 mill is in compliance with MSHA air qual- 
 ity regulations. 
 
 The first expansion of MIDAS took place 
 in 1982 when data from a scientific 
 survey of 22 mines were added to the 
 data base. The survey was conducted 
 from 1976 through 1978 in metal and 
 nonmetal mines by MSHA personnel. The 
 most recent expansion of MIDAS occurred 
 in 1985 when coal mine respirable dust 
 data were added to the data base. Unlike 
 the noncoal data, the great majority 
 of these samples were collected by coal 
 mine operators, as opposed to MSHA in- 
 spectors. MSHA updates the metal-non- 
 metal and coal mine compliance data on a 
 yearly basis. 
 
 The objectives of this report are to 
 describe the current contents of MIDAS, 
 to report analyses of coal and noncoal 
 mine respirable dust samples collected by 
 MSHA inspectors, and to evaluate the pro- 
 posed change in the metal and non- 
 metal respirable dust standard. The 
 report is divided into three major sec- 
 tions: A description of the MIDAS metal 
 and nonmetal subsystem, a description of 
 the MIDAS coal subsystem, and a discus- 
 sion of results from recent analyses of 
 these data. 
 
 MIDAS METAL AND NONMETAL SUBSYSTEM 
 
 REGULATORY REQUIREMENTS 
 
 MSHA regulates health and safety con- 
 ditions and practices in metal and non- 
 metal mines and mills under the authority 
 of the Federal Mine Safety and Health Act 
 of 1977, as amended (2.)* The specific 
 regulations are found in the Code of 
 Federal Regulations, Title 30 (3). Stan- 
 dards in these regulations for airborne 
 contaminants and physical agents were 
 adopted from the 1973 recommended 
 
 n •■■■■■■■■ ' — 
 
 J Underlmed numbers in parentheses re- 
 fer to items in the list of references 
 preceding the appendix at the end of this 
 report. 
 
 threshold limit values (TLV's) of the 
 American Conference of Governmental In- 
 dustrial Hygienists (ACGIH) (4_). Compli- 
 ance with these regulations is determined 
 by the collection of environmental sam- 
 ples by MSHA inspectors. 
 
 DATA DESCRIPTION 
 
 Since 1974 over 415,000 environmental 
 samples have been collected by MSHA and 
 records of these samples are edited and 
 stored in MIDAS. Details of the editing 
 procedure have been previously reported 
 (_5). MSHA has collected samples for 132 
 different contaminants, but samples for 
 10 contaminants account for 91 pet of the 
 
415,000 records. These contaminants are 
 listed in table 1. 
 
 Data from metal and nonmetal sampling 
 are of two types: personal (which are 
 either partial- or full-shift samples 
 collected on individuals) and area (which 
 are short-term "grab" samples collected 
 in the mine environment) . Each sample 
 record contains at a minimum the mine 
 identification number, date, contaminant 
 code, contaminant concentration, and 
 standard industrial classification (SIC) 
 code. In addition, the personal samples 
 contain codes to describe the worker's 
 occupation, and location. In 1983 MSHA 
 expanded the number of codes used to 
 describe occupation, location, and -com- 
 modity. These changes were incorporated 
 into the data base in 1984 by convert- 
 ing the pre-1983 codes to the new codes 
 adopted by MSHA. The new codes for 
 occupation, location, and commodity are 
 listed in appendix tables A-l through 
 A-3. 
 
 An additional 15,000 samples were 
 collected during a survey of 22 metal 
 and nonmetal underground mines. MSHA 
 conducted the survey in order to 
 determine exposures to quartz-bearing 
 dusts and to exhaust emissions produced 
 by diesel engines used underground. 
 
 The 22-mine-survey data are the only 
 data stored in MIDAS that were not 
 collected to determine compliance with 
 regulatory standards. 
 
 Environmental data from the 22-mine- 
 survey include full-shift, personal sam- 
 ples and short-term grab samples. Full- 
 shift samples were used to measure 
 concentrations of nitrogen dioxide, 
 respirable dust, and total dust. The 
 same miners were sampled for both dust 
 and nitrogen dioxide. Grab samples were 
 analyzed for a wide array of gases in- 
 cluding carbon monoxide, carbon dioxide, 
 and trace substances. Details of the 
 survey and the major findings have been 
 reported elsewhere (_6-7) . 
 
 The data base also contains an index of 
 all metal and nonmetal mine properties 
 in the United States. Each property is 
 listed with a unique mine identifica- 
 tion number, its location, the property 
 name, company name, approximate number of 
 employees, year-round or other status, 
 mine type, and standard industrial clas- 
 sification code (SIC). Pertinent infor- 
 mation from this file is added to the 
 records of environmental samples to 
 assist in grouping similar records for 
 analysis. The index is updated annually 
 by MSHA. 
 
 TABLE 1. - Contaminants most frequently 
 sampled in metal and nonmetal mines 
 
 Contaminant 
 
 Noise 
 
 Respirable dust with 
 >1 pet quartz 
 
 Carbon monoxide 
 
 Methane , 
 
 Radon daughters 
 
 Carbon dioxide 
 
 Total dust 
 
 Oxygen , 
 
 Respirable dust with 
 <1 pet quartz , 
 
 Nitrogen dioxide...., 
 Subtotal , 
 
 Others 
 
 Total 
 
 Sample 
 
 Type Number 
 
 FS 
 
 FS 
 ST 
 ST 
 ST 
 ST 
 FS 
 ST 
 
 FS 
 ST 
 
 NAp 
 NAp 
 
 NAp 
 
 112,126 
 
 50,508 
 39,830 
 36,412 
 34,910 
 30,767 
 26,637 
 21,251 
 
 14,706 
 12,293 
 
 379,440 
 35,740 
 
 415,180 
 
 Pet of 
 total 
 
 27.0 
 
 12.2 
 9.6 
 8.8 
 8.4 
 7.4 
 3.2 
 5.1 
 
 3.5 
 3.0 
 
 91.4 
 8.6 
 
 100.0 
 
 FS Full-shift personal exposure sample. 
 NAp Not applicable. 
 ST Short-term sample. 
 
 SOFTWARE 
 
 Data base software has undergone sev- 
 eral phases of development since 1980. 
 Each phase has resulted in the develop- 
 ment of more comprehensive and user- 
 friendly computer programs. Currently, 
 software is accessed through one program 
 that asks several questions, which re- 
 sults in the introduction of a sequence 
 of submenus. The submenus list the 
 available programs for the type of data 
 being analyzed and ask the user to select 
 the desired program. Once a program is 
 selected, a description of the program 
 is displayed and the user is asked to 
 specify detailed information. This in- 
 formation includes program options, file 
 names, code groups, and sort order. The 
 results may be immediately retrieved upon 
 completion of data processing, or in 
 cases where large volumes of data are 
 being processed the user may submit a job 
 
for overnight processing. This reduces 
 computing costs and ensures adequate 
 process time. Results can be retrieved 
 the following day. 
 
 The software for the metal and nonmetal 
 subsystem was designed to accomplish the 
 following tasks: record selection, file 
 creation, record sorting, data analysis, 
 and reporting of results. Records can be 
 selected based upon user-specified varia- 
 bles from the original master files or 
 from previously created user files, and 
 stored in a new data file. Sorting of 
 records in a preset order is required for 
 the use of certain programs, to ensure 
 the efficient use of computer process 
 time. Sorting requirements are noted in 
 the program descriptions found at the 
 
 beginning of each program. Analysis is 
 accomplished using a variety of descrip- 
 tive statistics such as the geometric 
 mean (GM), the geometric standard devia- 
 tion (GSD), and the percentage of samples 
 greater than the threshold limit value 
 (>TLV, pet). Graphic aids such as cumu- 
 lative frequency plots are also availa- 
 ble. Results are reported in the form of 
 tables or graphs. 
 
 In addition to software designed spe- 
 cifically for MIDAS, the user may select 
 other statistical software from the soft- 
 ware library maintained by the Bureau. 
 These programs are capable of calculating 
 a wide array of descriptive and infer- 
 ential statistics (8). 
 
 MIDAS COAL SUBSYSTEM 
 
 REGULATORY REQUIREMENTS 
 
 In 1970 a mandatory respirable dust 
 standard of 3.0 mg/m 3 was established for 
 underground coal mines under the Federal 
 Coal Mine Health and Safety Act of 1969. 
 This standard was subsequently lowered in 
 1972 to 2.0 mg/ra . Mandatory dust stan- 
 dards for surface work areas of under- 
 ground coal mines and surface mines also 
 became effective in 1972. These regula- 
 tions were continued under the Federal 
 Mine Safety and Health Act of 1977 (_9) , 
 which amended the 1969 coal act and 
 merged coal and noncoal regulations into 
 one law. In the 1969 act, "concentration 
 of respirable dust" was defined as a 
 measurement made with a Mining Research 
 Establishment (MRE, Casella 113A) instru- 
 ment or such equivalent concentration 
 measured with another device. The 1977 
 act changed the definition of "concen- 
 tration of respirable dust" to be the 
 "average concentration of respirable dust 
 measured with a device approved by the 
 Secretary and the Secretary of HEW." The 
 device approved for measuring respirable 
 dust uses a Dorr-Oliver 10-mm nylon 
 cyclone to remove the nonrespirable frac- 
 tion of dust sampled. Measurements made 
 with this device are converted to equiva- 
 lent MRE concentrations by multiplying by 
 a constant factor of 1.38 ( 1_0 ) . Specific 
 regulations detailing the collection of 
 
 respirable dust samples by mine operators 
 are found in the Code of Federal Regula- 
 tions, Title 30 (3). Since 1970, more 
 than 6 million respirable dust samples 
 have been collected by coal mine opera- 
 tors and MSHA inspectors to determine 
 compliance with the 2.0-mg/m 3 standard. 
 
 DATA DESCRIPTION 
 
 In 1985 the Bureau received the respi- 
 rable coal dust data from MSHA. Because 
 of the large volume of data, only the 
 1981 through 1985 records of samples col- 
 lected by MSHA inspectors, and the 1985 
 operator samples, are available in the 
 data base. However records dating as 
 far back as 1970 are stored on tape and 
 can be loaded into the data base upon 
 request. 
 
 The MSHA coal dust records had three 
 record formats: one corresponding to 
 samples collected from 1970 to 1980, 
 one corresponding to samples collected 
 from 1980 to 1984 by operators, and one 
 corresponding to samples collected from 
 1980 to 1984 by inspectors. However, in 
 order to conserve disk storage space and 
 to simplify software development and 
 analysis, the coal dust records were 
 revised to reflect only one record type. 
 Information that was not required for 
 analysis was eliminated. Information 
 that was retained but was not consistent 
 
between the different record types caused 
 the creation of blank fields in some 
 records. Records containing erroneous 
 codes were removed by editing. 
 
 Retained information that was recorded 
 in the same manner on all records in- 
 cludes State, mine identification number, 
 sample date, dust concentration, tons 
 of coal produced, and occupation code. 
 Information that appears on all records 
 but with different codes includes mine 
 type, sample type, and mining method. 
 Other information appearing on the rec- 
 ords includes mine section or mechanized 
 mining unit number, ventilation code, and 
 the MSHA field office code. Table A-4 
 lists the most frequently used occupation 
 codes, and tables A- 5 through A- 7 list 
 the codes used to describe mine type, 
 sample type, and mining method. In addi- 
 tion to the information listed above, 
 every record contains a numerical code 
 
 that allows rapid sorting into one of 
 four groups: 1970-80 inspector sample, 
 1970-80 operator sample, 1980-84 inspec- 
 tor sample, and 1980-84 operator sample. 
 
 SOFTWARE 
 
 Software is currently being developed 
 to analyze the coal dust data, and wher- 
 ever possible, software developed for the 
 metal and nonmetal subsystem is being 
 modified for use with the coal subsystem. 
 Examples of software under development 
 include trends programs to compute sta- 
 tistics for years, groups of years, and 
 occupations; table programs to compute 
 statistics for data grouped by occupa- 
 tion, mining methods, and sample types; 
 and graphics programs to produce plots by 
 occupation, mining method, and sample 
 type. 
 
 RESPIRABLE DUST ANALYSIS 
 
 METAL AND NONMETAL 
 
 Since 1974 MSHA inspectors have col- 
 lected more than 50,000 gravimetric sam- 
 ples for dust containing respirable 
 quartz (RQ) . The RQ sample is collected 
 on a filter after the aerosol has passed 
 through a cyclone preclassif ier at a flow 
 rate of 1.7 L/min. The TLV for RQ is de- 
 termined by collecting a respirable dust 
 sample, analyzing for quartz content, ^ 
 and calculating the TLV by dividing per- 
 cent RQ plus 2 into 10 when the quartz 
 content (percent RQ) is >1 pet ( 4_) . The 
 resultant TLV is expressed in milligrams 
 per cubic meter. The TLV for RQ is in- 
 versely proportional to the quartz con- 
 tent of the sample. Thus, for a given 
 exposure level the magnitude of the toxi- 
 city is proportional to the quartz con- 
 tent (11). The factor 2 in the TLV 
 formula ensures that dust exposures will 
 not be excessively high when the quartz 
 content is less than 5 pet and effec- 
 tively limits the dust concentration to 
 5 mg/m when no quartz is identified in 
 the sample. 
 
 4 puartz content is determined by X-ray 
 diffraction after the filter has been 
 weighed. 
 
 In 1983 MSHA proposed to revise many of 
 the existing health regulations (12) . 
 Included in these revisions was a pro- 
 posed change in the RQ standard. The 
 proposed new standard, which is still 
 undergoing review, is 100 yg/m 3 of respi- 
 rable quartz. The effects of changing 
 the RQ standard on compliance deter- 
 minations are discussed in a subsequent 
 section. 
 
 The yearly statistics for RQ are shown 
 in table 2. Data shown in table 2 must 
 be interpreted in the context of MSHA 
 policy and regulatory changes that may 
 have altered sampling strategies. These 
 changes have been discussed in depth 
 elsewhere ( 13 ) , but warrant a brief 
 review. 
 
 MSHA inspectors collect dust samples 
 in order to determine compliance. This 
 is accomplished by sampling workers 
 thought to have the greatest risk of 
 overexposure, and a sample exceeding the 
 standard by 20 pet is considered out of 
 compliance. 
 
 The sampling strategy used in metal and 
 nonmetal mines and mills tends to be 
 judgmental in that it is not based on a 
 
 probability model assuming randomness. 
 This creates a statistical problem: These 
 
TABLE 2. - Yearly statistics for RQ 
 
 Year 
 
 Samples 
 
 >TLV, 
 pet 
 
 Concentration, mg/nr 
 
 GM 
 
 Median 
 
 GSD 
 
 GM 
 C-TLV 
 
 1974 , 
 
 1975 , 
 
 1976 , 
 
 1977 , 
 
 1978 
 
 1979 , 
 
 1980 
 
 1981 , 
 
 1982 , 
 
 1983 , 
 
 1984 
 
 Total or 
 average. 
 
 284 
 2,648 
 6,223 
 7,566 
 7,840 
 7,780 
 4,744 
 4,423 
 1,640 
 3,399 
 3,961 
 
 50,508 
 
 44.37 
 27.95 
 25.16 
 18.90 
 15.46 
 13.62 
 14.69 
 16.69 
 17.26 
 17.01 
 17.22 
 
 0.58 
 .49 
 .51 
 .44 
 .40 
 .37 
 .40 
 .43 
 .46 
 .45 
 .45 
 
 0.54 
 .47 
 .48 
 .43 
 .38 
 .34 
 .37 
 .40 
 .43 
 .41 
 .40 
 
 2.62 
 2.94 
 3.08 
 2.96 
 3.00 
 2.98 
 2.63 
 2.58 
 2.72 
 2.35 
 2.43 
 
 18.04 
 
 .43 
 
 .40 
 
 2.84 
 
 0.86 
 .53 
 .45 
 .37 
 .34 
 .31 
 .33 
 .36 
 .39 
 .40 
 .39 
 
 .37 
 
 GM Geometric mean. 
 
 GM C-TLV Geometric mean concentration-to-TLV ratio. 
 
 GSD Geometric standard deviation. 
 
 TLV Threshold limit value. 
 
 data may not be representative of all ex- 
 posures, so the classical assumptions of 
 randomness, homoscedasticity (homogeneous 
 variance) , and normal distribution may 
 not apply. In addition, anything that 
 affects the number of samples collected 
 is important because it alters the sampl- 
 ing strategy. Two examples of such al- 
 terations are the Federal Mine Safety and 
 Health Act of 1977 ( 2^ , and the tempo- 
 rary removal of stone, sand and gravel, 
 and other commodities from MSHA's juris- 
 diction for most of fiscal year 1982. 
 
 The passage of the 1977 act was fol- 
 lowed by an increase in the number of RQ 
 samples collected over previous years 
 until 1980 when internal MSHA policy 
 changes caused a marked reduction in the 
 number of RQ samples. This was followed 
 in 1982 with the temporary loss of juris- 
 diction over stone, sand and gravel, and 
 other commodities accompanied by a sharp 
 decrease in the number of RQ samples as 
 shown in table 2. With the restoration 
 of MSHA's jurisdiction over stone, sand 
 and gravel, and other commodities in the 
 1983-84 period, the number of samples 
 reported rebounded close to the level in 
 1980. Overall, the data in table 2 show 
 that for the more than 50,000 RQ 
 samples over the 1974-84 period, more 
 than 18 pet ("9,000) of the samples 
 exceeded the TLV. 
 
 Exposures by Mine Type and Occupation 
 
 Table 3 shows RQ exposures by mine type 
 for two time periods, 1974-79 and 1980- 
 84. The location groups, underground, 
 surface, and mill, are defined in table 
 A-2, and the commodity groups, stone, 
 metal, nonmetal, and sand and gravel, are 
 defined in table A-3. For each group 
 the table shows the number of samples, 
 geometric mean concentration (GM CONC) , 
 geometric mean concentration-TLV ratio 
 (GM C-TLV), percentage of samples exceed- 
 ing the TLV, and the percentage of 
 workers wearing respirators at the time 
 the sample was collected. 
 
 Several mine types have shown substan- 
 tial improvement from the 1974-79 to 
 1980-84 sample period. Nonmetal mills 
 have reduced the percentage of samples 
 exceeding the TLV from 40.1 pet to 23.9 
 pet, while increasing the percentage of 
 workers wearing respirators from 49.9 pet 
 to 64.9 pet. The GM CONC was reduced 
 from 0.84 to 0.66 mg/m 3 . Overexposures 
 were also sharply reduced at industrial 
 sand mills (32.9 to 22.1 pet), while 
 workers wearing respiratory protection 
 increased 13.7 pet. At both nonmetal 
 mills and industrial sand mills, the 
 product is typically a crushed or ground 
 silica sand with a very high quartz 
 content. 
 
TABLE 3. - RQ exposures by mine type for 1974-79 and 1980-84 
 
 Commodity group 
 
 Metal: 
 
 Samples 
 
 GM CONC mg/m 3 .. 
 
 GM C-TLV 
 
 >TLV pet.. 
 
 PROT pet. . 
 
 Nonmetal: 
 
 Samples 
 
 GM CONC mg/m 3 .. 
 
 GM C-TLV 
 
 >TLV pet. . 
 
 PROT pet. . 
 
 Sand and gravel: 
 
 Samples 
 
 GM CONC mg/m 3 . . 
 
 GM C-TLV 
 
 >TLV pet.. 
 
 PROT pet.. 
 
 Stone: 
 
 Samples 
 
 GM CONC rag/m 3 .. 
 
 GM C-TLV 
 
 >TLV pet. . 
 
 PROT pet.. 
 
 Total: ' 
 
 Samples 
 
 GM CONC mg/m 3 .. 
 
 GM C-TLV 
 
 >TLV pet. . 
 
 PROT pet.. 
 
 1974-79 
 
 UG 
 mine 
 
 2,815 
 0.57 
 0.46 
 18.3 
 39.5 
 
 608 
 0.74 
 0.52 
 26.8 
 32.9 
 
 NAp 
 NAp 
 NAp 
 NAp 
 NAp 
 
 562 
 0.86 
 0.44 
 19.4 
 34.9 
 
 3,985 
 0.63 
 0.47 
 19.8 
 37.9 
 
 Surface 
 mine 
 
 1,604 
 0.30 
 0.28 
 11.2 
 25.9 
 
 1,820 
 0.43 
 0.39 
 18.7 
 39.4 
 
 4,192 
 0.24 
 0.28 
 12.8 
 22.6 
 
 11,347 
 0.37 
 0.29 
 13.4 
 23.4 
 
 18,963 
 0.34 
 0.30 
 13.6 
 25.0 
 
 Mill Total 
 
 1,892 
 0.46 
 0.47 
 24.3 
 35.6 
 
 2,252 
 0.84 
 0.78 
 40.1 
 49.9 
 
 799 
 0.37 
 0.60 
 32.9 
 46.3 
 
 4,385 
 0.58 
 0.49 
 25.7 
 42.9 
 
 9,328 
 0.58 
 0.55 
 29.5 
 43.4 
 
 6,311 
 0.45 
 0.41 
 18.3 
 34.9 
 
 4,680 
 0.64 
 0.57 
 30.1 
 43.6 
 
 4,991 
 0.26 
 0.32 
 16.0 
 26.4 
 
 16,294 
 0.43 
 0.34 
 16.9 
 29.1 
 
 32,276 
 0.43 
 0.37 
 19.0 
 31.9 
 
 1980-84 
 
 UG 
 mine 
 
 1,548 
 0.55 
 0.42 
 17.0 
 58.3 
 
 260 
 0.58 
 0.43 
 18.5 
 58.5 
 
 NAp 
 NAp 
 NAp 
 NAp 
 NAp 
 
 484 
 0.70 
 0.34 
 14.0 
 32.2 
 
 2,292 
 0.58 
 0.40 
 16.6 
 52.8 
 
 Surface 
 mine 
 
 1,093 
 0.31 
 0.29 
 11.7 
 45.2 
 
 612 
 0.38 
 0.29 
 18.7 
 47.9 
 
 1,905 
 0.35 
 0.37 
 14.5 
 36.6 
 
 5,330 
 0.39 
 0.29 
 11.9 
 35.5 
 
 8,940 
 0.37 
 0.31 
 12.6 
 37.8 
 
 Mill 
 
 1,080 
 0.37 
 0.35 
 15.9 
 50.0 
 
 1,425 
 0.66 
 0.53 
 23.9 
 64.9 
 
 1,413 
 0.38 
 0.50 
 22.1 
 59.0 
 
 3,014 
 0.49 
 0.43 
 21.5 
 51.0 
 
 6,932 
 0.47 
 0.45 
 21.3 
 55.3 
 
 Total 
 
 3,721 
 0.41 
 0.36 
 15.2 
 52.1 
 
 2,297 
 0.56 
 0.44 
 20.6 
 59.6 
 
 3,318 
 0.36 
 0.42 
 17.8 
 46.1 
 
 8,828 
 0.43 
 0.34 
 15.3 
 40.6 
 
 18,164 
 0.43 
 0.37 
 16.4 
 
 46.4 
 
 GM CONC Geometric mean concentration. 
 
 GM C-TLV Geometric mean concentration-to-TLV ratio. 
 
 NAp Not applicable. 
 
 PROT Respiratory protection. 
 
 TLV Threshold limit value. 
 
 UG Underground. 
 
 68 records are excluded because no SIC code was reported. 
 
 Overall the table shows that the use of 
 respiratory protection is increasing and 
 that dust levels are decreasing. Seven 
 of the eleven mine types show reduced 
 GM CONC while only four (surface stone 
 quarries, metal mines, sand and gravel 
 mills, and surface quarries) show 
 slightly higher GM CONC. Sand and gravel 
 quarries had a small increase in the per- 
 cent of samples exceeding the TLV despite 
 a large drop in the number of samples 
 collected. 
 
 Table 4 shows the changes in the per- 
 centage of samples exceeding the TLV and 
 the GM CONC for 17 frequently sampled 
 occupations for the same time periods, 
 1974-79 and 1980-84. Nearly 90 pet of 
 the over 50,000 RQ samples are accounted 
 for in the table, and each occupation 
 has a minimum of 200 samples in each time 
 period. The bagging, flotation, jack 
 stoper drill, and trucker occupations had 
 10 pet fewer samples exceeding the TLV. 
 Stope miner, motorman, and laborer and 
 
TABLE 4. - RQ exposures by metal and nonmetal occupation 1 for 1974-79 and 1980-84 
 
 Occupation 
 
 1974-79 
 
 Samples 
 
 >TLV, 
 pet 
 
 GM CONC, 
 mg/m 3 
 
 1980-84 
 
 Samples 
 
 >TLV, 
 pet 
 
 GM CONC, 
 mg/m 3 
 
 Change 
 >TLV, 
 pet 
 
 Bagging and packing 
 
 Flotation 
 
 Jack stoper drill 
 
 Trucker 
 
 Ball and rod mill 
 
 Cleanup man 
 
 Sizing and washing 
 
 Mechanic 
 
 Crusher 
 
 Dryer and kiln 
 
 Pneumatic drill 
 
 Bulldozer 
 
 Wagon drill 
 
 Front-end loader 
 
 Stope miner 
 
 Motorman 
 
 Laborer and bullgang. . . . 
 Total or average. . . 
 
 1,384 
 
 422 
 
 470 
 
 409 
 
 1,178 
 
 3,344 
 
 1,239 
 
 1,318 
 
 4,894 
 
 1,220 
 
 703 
 
 792 
 
 1,030 
 
 9,254 
 
 964 
 
 743 
 
 350 
 
 44.0 
 19.0 
 25.5 
 14.2 
 31.4 
 28.3 
 23.3 
 14.5 
 23.5 
 24.1 
 23.2 
 12.9 
 23.8 
 7.6 
 13.0 
 12.5 
 18.0 
 
 0.73 
 .43 
 .84 
 .37 
 .62 
 .54 
 .41 
 .42 
 .51 
 .46 
 .55 
 .30 
 .50 
 .29 
 .47 
 .33 
 .54 
 
 1,360 
 232 
 201 
 850 
 341 
 
 1,354 
 510 
 372 
 
 3,434 
 761 
 344 
 328 
 331 
 
 4,195 
 284 
 344 
 221 
 
 33.1 
 
 8.2 
 14.9 
 
 4.2 
 21.7 
 21.2 
 17.5 
 
 8.9 
 20.0 
 22.7 
 22.1 
 11.9 
 23.0 
 
 6.9 
 13.4 
 13.1 
 19.9 
 
 0.59 
 .33 
 .67 
 .33 
 .43 
 .49 
 .39 
 .39 
 .48 
 .46 
 .53 
 .32 
 .49 
 .34 
 .51 
 .34 
 .49 
 
 -10.9 
 
 -10.8 
 
 -10.6 
 
 -10.0 
 
 -9.7 
 
 -7.1 
 
 -5.8 
 
 -5.6 
 
 -3.5 
 
 -1.4 
 
 -1.1 
 
 -1.0 
 
 -.8 
 
 -.7 
 
 .4 
 
 .6 
 
 1.9 
 
 29,714 
 
 21.1 
 
 .49 
 
 15,462 
 
 16.6 
 
 .45 
 
 -4.5 
 
 GM CONC 
 
 Geometric mean 
 Threshold limit 
 
 TLV 
 See table A-l for corapl 
 
 concentrati 
 
 value, 
 ete listing 
 
 on. 
 
 of codes, occupations, and samples. 
 
 NOTE. — Selected occupations had at least 200 samples in each period. 
 
 bullgang occupations show slight in- 
 creases (less than 2 pet) in the percent- 
 age of samples exceeding the TLV. The 
 average reduction in the percentage of 
 samples exceeding the TLV was 4.5 pet 
 for the occupations shown in the table. 
 Dramatic changes in the percentage of 
 sampled workers wearing respiratory pro- 
 tection for these occupations are illus- 
 trated in table A-8. All 17 occupations 
 experienced an increase in the use of 
 respiratory protection ranging from 5 to 
 20 pet despite reduction in dust levels. 
 The average respirator wear increase for 
 the occupations was 14 pet. The increase 
 in the use of respiratory protection is 
 attributed to increased worker awareness 
 of health problems associated with respi- 
 rable dust containing quartz and MSHA's 
 respiratory protection program. 
 
 Effect of Changing the RQ Standard 
 
 As previously mentioned, MSHA has pro- 
 posed to change the TLV for RQ from 
 the formula to 100 Ug/m 3 of respirable 
 
 quartz. MIDAS can be used to evaluate 
 the effect of this change because every 
 respirable dust record has the time- 
 weighted average dust concentration and 
 the percentage of quartz, thus the time- 
 weighted average quartz concentration can 
 be calculated for each record and com- 
 pared to the proposed standard. Table 5 
 summarizes the quartz statistics for sel- 
 ected commodities. These commodities ac- 
 count for 46,846 of the 50,400 (92.7 pet) 
 of the samples summarized in table 3. 
 
 A previous paper (13) showed that both 
 respirable dust and quartz concentrations 
 approximated log-normal distributions. 
 When a distribution is log-normal, the 
 geometric mean or median and geometric 
 standard deviation are the best measures 
 of central tendency and dispersion. In 
 table 5 both the arithmetic and geometric 
 parameters are shown to facilitate com- 
 parisons with other sets of data where 
 only the arithmetic mean (AM) and arith- 
 metic standard deviation were computed. 
 The GM CONC's are all well below 
 the proposed standard, whereas six 
 
TABLE 5. - Quartz statistics for selected commodities 1 
 
 Commodity 
 
 Samples 
 
 Concentration, yg/m 3 
 
 AM ASD GM GSD 
 
 Quartz, pet 
 (AM) 
 
 Metal: 
 
 Copper 
 
 Gold 
 
 Iron 
 
 Lead and zinc 
 
 Molybdenum 
 
 Silver 
 
 Uranium 
 
 Nonmetal: 
 
 Common clay 
 
 Fire clay 
 
 Nonmetal, not elsewhere classified. 
 
 Phosphate rock 
 
 Sand and gravel 
 
 Stone: 
 
 Cement 
 
 Granite: 
 
 Crushed • 
 
 Dimension 
 
 Limestone: Crushed 
 
 Sandstone: 
 
 Crushed 
 
 Dimension • 
 
 Stone: Crushed 
 
 Traprock : Crushed 
 
 2,240 
 1,150 
 2,593 
 1,044 
 600 
 756 
 1,158 
 
 2,792 
 784 
 881 
 531 
 
 8,309 
 
 1,232 
 
 3,206 
 
 1,113 
 
 13,054 
 
 3,421 
 434 
 689 
 869 
 
 84 
 93 
 49 
 74 
 101 
 68 
 50 
 
 94 
 98 
 209 
 58 
 75 
 
 35 
 
 68 
 
 102 
 
 34 
 
 140 
 
 191 
 
 120 
 
 44 
 
 254 
 262 
 121 
 270 
 193 
 137 
 181 
 
 225 
 199 
 563 
 106 
 284 
 
 68 
 
 238 
 195 
 121 
 
 294 
 
 690 
 
 339 
 
 76 
 
 30 
 37 
 21 
 28 
 50 
 32 
 22 
 
 40 
 45 
 55 
 29 
 27 
 
 16 
 
 30 
 46 
 15 
 
 52 
 44 
 40 
 21 
 
 8.6 
 10.0 
 9.5 
 8.3 
 9.1 
 9.2 
 7.5 
 
 7.7 
 8.4 
 
 20.7 
 9.1 
 
 13.1 
 
 4.0 
 
 11.4 
 
 11.4 
 
 4.6 
 
 22.9 
 
 21.7 
 
 16.1 
 
 6.8 
 
 AM Arithmetic mean. 
 
 ASD Arithmetic standard deviation. 
 
 GM Geometric mean. 
 
 GSD Geometric standard deviation. 
 
 'See table A-3 for complete listing of 
 
 SIC codes, commodities, and samples. 
 
 commodities have AM CONC's exceeding 
 the proposed standard of 100 yg/m 3 of 
 respirable quartz. 
 
 It would be expected that fewer samples 
 would exceed the new standard. For exam- 
 ple, if a worker is sampled during a 
 work -shift and a mass of 0.82 mg of 
 respirable dust is deposited on the 
 filter, then the time-weighted average 
 concentration of dust for that sample is 
 1.0 mg/ra 3 . If the sample contains 9 pet 
 quartz, the allowable respirable dust 
 level is 0.91 mg/m 3 under the current 
 standard. The time-weighted average res- 
 pirable quartz concentration is 0.090 
 mg/m 3 . This sample exceeds the current 
 standard but not the proposed standard 
 of 100 yg/m 3 (0.100 mg/m 3 ) of respirable 
 quartz. Table 6 shows the percentage 
 
 of samples exceeding both standards for 
 the commodities listed in table 5. The 
 proposed standard would result in the 
 reporting of about 4 pet fewer samples 
 exceeding the TLV, and no mining 
 activity would be adversely affected. 
 
 COAL 
 
 The objective of respirable dust sam- 
 pling in coal mines is to ensure compli- 
 ance with the 2.0-mg/m 3 coal mine dust 
 standard or with the more rigorous stan- 
 dard if the mine dust aerosol contains 
 more than 5 pet quartz. A mine is out of 
 compliance if the arithmetic average of 
 five samples is over the standard. MSHA 
 inspectors and coal mine operators regu- 
 larly sample miners or areas known to 
 
10 
 
 TABLE 6. - Effect of changing the RQ TLV 
 
 Commodity 1 
 
 Samples 
 
 >TLV, 
 pet 
 
 100 yg/m 3 ; 
 pet 
 
 Change, 
 pet 
 
 Metal: 
 
 Copper 
 
 Gold 
 
 Iron 
 
 Lead and zinc 
 
 Molybdenum 
 
 Silver 
 
 Uranium 
 
 Nonmetal: 
 
 Common clay 
 
 Fire clay 
 
 Nonmetal, not elsewhere classified 
 
 Phosphate rock 
 
 Sand and gravel 
 
 Stone: 
 
 Cement 
 
 Granite: 
 
 Crushed 
 
 Dimension 
 
 Limestone: Crushed 
 
 Sandstone: 
 
 Crushed 
 
 Dimension 
 
 Stone: Crushed 
 
 Traprock: Crushed 
 
 All commodities: 2 
 
 Total or average 
 
 TLV Threshold limit value. 
 
 1 See table A-3 for complete listing of SIC code 
 Includes data for commodities not shown in the 
 
 2,240 
 1,150 
 2,593 
 1,044 
 600 
 756 
 1,158 
 
 2,792 
 
 784 
 
 881 
 
 531 
 
 8,309 
 
 1,232 
 
 19.1 
 22.7 
 12.1 
 16.6 
 32.2 
 18.9 
 11.3 
 
 29.3 
 31.9 
 40.1 
 15.6 
 16.7 
 
 13.0 
 
 3,206 
 
 16.9 
 
 1,113 
 
 30.0 
 
 13,054 
 
 9.9 
 
 3,421 
 
 34.1 
 
 434 
 
 30.6 
 
 689 
 
 27.6 
 
 869 
 
 13.1 
 
 50,440 18.0 
 
 15.0 
 18.4 
 
 9.6 
 12.6 
 26.0 
 13.5 
 
 7.9 
 
 21.7 
 23.8 
 37.3 
 11.5 
 14.2 
 
 7.6 
 
 13.8 
 
 25.0 
 
 5.8 
 
 31.8 
 
 29.3 
 
 25.0 
 
 9.2 
 
 14.1 
 
 -4.0 
 -4.3 
 -2.5 
 -4.6 
 -6.2 
 -5.4 
 -3.4 
 
 -7.6 
 -7.8 
 -2.8 
 -4.1 
 -2.5 
 
 -5.4 
 
 -3.1 
 -5.0 
 -4.1 
 
 -2.3 
 -1.3 
 -2.6 
 -3.9 
 
 -3.9 
 
 s, commodities, and samples, 
 table. 
 
 have high dust exposure. In underground 
 mines, MSHA inspectors are required to 
 sample specific occupations referred to 
 as designated occupations (DO). A DO is 
 an occupation on a mining operation that 
 is typically exposed to the highest res- 
 pirable dust concentration. Examples of 
 DO's would include the longwall shearer 
 operator or the continuous miner opera- 
 tor. In addition, the MSHA inspectors 
 sample other underground occupations sus- 
 pected to have high dust exposures such 
 as roof bolters. These occupations are 
 referred to as nondesignated occupations 
 (NDO's). 
 
 The results from the respirable coal 
 dust analysis reported below are re- 
 stricted to samples collected only by 
 MSHA inspectors from 1981-84, and are for 
 the most part restricted to DO and NDO 
 
 samples collected in underground mines. 
 Results reported for surface coal mines 
 are limited to specific occupations. 
 Mine compliance data are not reported, 
 but the percentage of samples exceeding 
 the 2.0 mg/m 3 standard is reported. It 
 should be emphasized that, in coal mines, 
 a single sample that exceeds the standard 
 does not automatically place the mine in 
 a noncompliance status. 
 
 MSHA is required to inspect all under- 
 ground coal mines four times each year, 
 collecting dust samples twice a year, 
 but the population of mines inspected 
 changes from year to year depending upon 
 the market for coal and other factors. 
 From 1981 through 1984, MSHA inspectors 
 collected about 66,000 full-shift, per- 
 sonal, respirable dust samples in under- 
 ground coal mines. About 16,500 samples 
 
 _^^^>^^^M^^M 
 
 ^H^M^H 
 
1 1 
 
 were collected at approximately 1,550 
 different underground mines per year. An 
 additional 10,000 samples per year were 
 collected at surface coal mines. 
 
 Table 7 shows the yearly trends in 
 exposure for underground DO and NDO sam- 
 ples. The sample size, the mean dust 
 concentration, and the percentage of sam- 
 ples exceeding the 2.0-mg/m 3 standard 
 remained relatively constant from 1981 
 through 1984. Between 10 and 12 pet of 
 the samples exceeded the standard and 
 the GM CONC fluctuated between 0.59 and 
 0.69 mg/m 3 . A coal mine is out of 
 compliance only when an average of five 
 
 samples exceeds the 2.0 mg/m 5 standard, 
 thus there are far fewer mines out of 
 compliance than there are samples exceed- 
 ing the standard. On average, about 
 1,800 samples exceeded the standard each 
 year. 
 
 Table 8 shows the 1984 statistics for 
 DO and NDO underground mine samples 
 grouped by mining method. The table 
 accounts for more than 98 pet of all 
 underground mine samples, despite the 
 fact that methods of mining with less 
 than 50 samples are not included because 
 of small sample size. Mines with long- 
 wall plows or shears have the highest GM 
 
 TABLE 7. - Yearly trends in respirable dust exposure for 
 samples collected in underground coal mines 
 
 Statistic 
 
 1981 
 
 1982 
 
 1983 
 
 1984 
 
 Samples 
 
 >TLV pet. . 
 
 Concentration, mg/m : 
 
 AM 
 
 ASD 
 
 GM 
 
 GSD 
 
 Median 
 
 16,233 
 11.9 
 
 1.12 
 1.88 
 0.66 
 2.80 
 0.80 
 
 16,244 
 11.0 
 
 1.12 
 1.86 
 0.69 
 2.68 
 
 0.80 
 
 16,687 
 9.9 
 
 1.01 
 1.40 
 0.59 
 2.85 
 0.70 
 
 16,452 
 11.9 
 
 1.12 
 1.97 
 0.65 
 2.83 
 0.70 
 
 AM Arithmetic mean. 
 
 ASD Arithmetic standard deviation. 
 
 GM Geometric mean. 
 
 GSD Geometric standard deviation. 
 
 TLV Threshold limit value. 
 
 TABLE 8. - 1984 coal dust data by underground mining method 
 
 Mining method 
 
 Samples 
 
 Concentration, mg/m 3 
 
 GM 
 
 GSD 
 
 >TLV, 
 pet 
 
 Longwall plow 
 
 Longwall shear 
 
 Conventional cut machine 
 
 Continuous ripper 
 
 Continuous bore 
 
 Continuous auger 
 
 Scoop shoot solids 
 
 Scoop cut machine 
 
 Conventional shoot with loading machine 
 
 Hand-load shoot solid 
 
 GM Geometric mean. 
 
 GSD Geometric standard deviation. 
 
 TLV Threshold limit value. 
 
 NOTE. — For inclusion in the table there had to be at least 50 samples and the min- 
 ing methods are ranked by the GM concentration. 
 
 151 
 
 963 
 
 1,558 
 
 10,946 
 
 153 
 
 553 
 
 525 
 
 997 
 
 84 
 
 258 
 
 1.64 
 1.29 
 .67 
 .66 
 .61 
 .57 
 .54 
 .47 
 .39 
 .38 
 
 2.25 
 2.18 
 2.69 
 2.75 
 3.02 
 4.06 
 3.18 
 2.96 
 2.70 
 2.58 
 
 43.7 
 
 25.2 
 
 10.2 
 
 10.9 
 
 10.5 
 
 20.8 
 
 9.3 
 
 7.9 
 
 7.1 
 
 3.9 
 
12 
 
 CONC (1.64 and 1.29 mg/m 3 , respectively) 
 and the greatest percentage of samples 
 exceeding the 2.0-mg/m 3 standard (43.7 
 and 25.2 pet, respectively). However, 
 many more samples (10,946) were recorded 
 at mines using continuous rippers, where 
 the GM CONC was 0.66 mg/m 3 and 10.9 pet 
 of the samples exceeded the standard. 
 Mines with augers had a lower GM CONC 
 (0.57 mg/m 3 ) but 21 pet of the samples 
 exceeded the standard. Augers also have 
 the highest geometric standard deviation 
 (4.06), which suggests that some of the 
 reported dust concentrations are ex- 
 tremely high. 
 
 Table 9 is a cumulative frequency table 
 that compares DO and NDO samples for the 
 auger, continuous ripper, and longwall 
 mining methods. Samples from longwall 
 shears and plows were combined to in- 
 crease the sample size. Four percentiles 
 are shown— 20th, 50th, 80th, and 95th. A 
 fifth value, the percentage of samples 
 exceeding the 2.0-mg/m 3 standard (TLV) , 
 is also shown. This can be converted to 
 a percentile for each mining method by 
 subtracting the value from 100. The per- 
 centiles represent low exposure, median 
 exposure, moderate exposure, and high 
 exposure levels. For instance, at the 
 
 95th percentile concentration 5 pet of 
 the samples exceed that value. With one 
 exception the DO percentile values are 
 greater than or equal to the correspond- 
 ing NDO values. The only exception is 
 the 95th percentile longwall NDO value, 
 which is 0.3 mg/m 3 higher than the DO 
 values. This finding confirms MSHA's 
 selection of DO's as those occupations 
 with the highest overall exposures. The 
 auger samples have the highest 95th per- 
 centile values (7.8 and 6.0 rag/m 3 ) and 
 the lowest 20th percentile values (0.1 
 mg/m 3 ). This explains the high standard 
 deviations for auger samples shown in 
 table 8. Figure 1 illustrates the dis- 
 tribution of these data, which is approx- 
 imately log-normal and different for each 
 mining method and sample type group. 
 
 More mines use continuous rippers than 
 any other mining method and these mines 
 have the greatest number of samples 
 exceeding the 2.0-mg/m 3 standard. Table 
 10 shows that the average number of 
 samples collected per year at mines using 
 continuous rippers was 11,036 and that 
 the average number of samples over the 
 standard was 1,120 or 10.1 pet. During 
 any single year between 1981 and 1984 
 about 43 pet of the mines with continuous 
 
 TABLE 9. - Differences between DO and NDO samples for three 
 mining methods 
 
 Group 
 
 Samples 
 
 Percentile concentrations, mg/ 
 
 m 
 
 20th 
 
 50th 80th 95th 
 
 >TLV, 
 pet 
 
 Auger: 
 
 DO 
 
 NDO 
 
 Continuous ripper: 
 
 DO 
 
 NDO 
 
 Longwall: 
 
 DO 
 
 NDO 
 
 116 
 
 437 
 
 2,5 20 
 8,426 
 
 296 
 
 818 
 
 0.1 
 0.1 
 
 0.4 
 0.2 
 
 1.1 
 
 0.7 
 
 0.5 
 0.5 
 
 0.8 
 
 0.7 
 
 1.7 
 1.4 
 
 2.7 
 
 1.8 
 
 1.8 
 1.5 
 
 2.7 
 2.2 
 
 7.8 
 6.0 
 
 3.6 
 
 2.7 
 
 4.0 
 4.3 
 
 28.4 
 18.8 
 
 14.2 
 9.9 
 
 34.8 
 25.2 
 
 DO Designated occupation. 
 NDO Nondesignated occupation. 
 TLV Threshold limit value. 
 
 i^MM 
 
95 
 
 80 
 
 50 
 
 o 20 
 
 UJ 
 3 
 O 
 UJ 
 
 tr 
 
 U- 
 
 15 
 
 1 
 
 A 
 
 \ i r-" 
 
 - 
 
 / KEY 
 
 
 1 • DO 
 
 
 O NDO 
 
 V i d 
 
 l i I 
 
 0.7 
 
 20 6- 
 
 2.0 3.0 4.0 5.0 
 
 95 
 
 80 - 
 
 50 - 
 
 2.0 3.0 4.0 
 
 
 1 1 ' 
 
 i i \J 
 
 ? — • — 
 
 c 
 
 
 
 
 
 jS/S • 
 
 
 
 Jl 
 
 I 1 i 
 
 KEY 
 
 • DO 
 O NDO 
 
 l l 1 
 
 i i i i 
 
 20i 
 0.1 
 
 CONCENTRATION, mg/m 2 
 
 0.5 
 
 1.0 
 
 2.0 3.0 5.0 7.0 10.0 
 
 FIGURE 1.— Logarithmic probability plots of longwall {A), continuous ripper (8), and auger (C) samples grouped by designated 
 occupation (DO) and nondesignated occupation (NDO). 
 
 rippers had at least one sample exceeding 
 the standard. For mines with longwall 
 shears or plows, only 247 samples per 
 year exceeded the standard at 40 differ- 
 ent mines. Every mine reported to have a 
 longwall operation also used continuous 
 rippers for mine development. The dust 
 concentrations were greater at mines with 
 longwall operations but there were nearly 
 
 nine times more continuous ripper opera- 
 tions with one or more samples exceeding 
 the 2.0-mg/m- 5 standard. However, as pre- 
 viously mentioned this does not mean 
 that all of these mines were out of 
 compliance, because compliance with the 
 standard is determined by an average of 
 five samples. 
 
l<* 
 
 TABLE 10. - Average number of samples exceeding 2.0 mg/m 3 for 1981-84 and 
 average number of mines with samples exceeding 2.0-mg/m 3 standard 
 
 Mining method 
 
 Number 
 
 Samples 
 
 >TLV 
 
 Number 
 
 i£L 
 
 Mines 
 
 Number 
 
 >TLV 
 
 Number 
 
 pet 
 
 Continuous ripper . 
 
 Conventional cut machine 
 
 Scoop cut machine 
 
 Longwall shear 
 
 Continuous auger 
 
 Scoop shoot solids 
 
 Longwall plow . 
 
 Conventional shoot with loading machine. 
 
 Continuous bore • 
 
 Hand-load shoot solid < 
 
 11,036 
 
 1,720 
 
 1,027 
 
 713 
 
 530 
 
 616 
 
 130 
 
 131 
 
 91 
 
 142 
 
 1,120 
 
 201 
 
 76 
 
 193 
 
 95 
 
 50 
 
 54 
 
 10 
 
 7 
 
 7 
 
 10.1 
 
 11.7 
 
 7.4 
 
 27.1 
 
 17.9 
 
 8.2 
 
 41.5 
 
 7.4 
 
 7.7 
 
 4.8 
 
 808 
 
 195 
 
 151 
 
 48 
 
 70 
 
 107 
 
 9 
 
 21 
 
 13 
 
 26 
 
 350 
 
 74 
 
 36 
 
 33 
 
 29 
 
 25 
 
 7 
 
 4 
 
 3 
 
 3 
 
 43.2 
 38.1 
 24.1 
 69.8 
 41.6 
 23.4 
 80.6 
 20.5 
 21.6 
 12.4 
 
 TLV Threshold limit value. 
 
 NOTE. — The mining methods are ranked by the number of mines with at least 1 sample 
 over the TLV. 
 
 Table 11 shows the 1984 coal mine dust 
 data for the most frequently sampled 
 underground and surface occupations. 
 Four occupations, longwall shear or plow 
 operator, return side auger jack setter, 
 longwall jack setter, and surface fine 
 coal plant operator, had more than 28 pet 
 of the samples exceeding the 2.0-mg/m- 5 
 standard for a total of 382 samples. 
 In comparison, 558 samples collected on 
 continuous miner operators (14.2 pet) and 
 helpers (13.7 pet), and 420 (11.9 pet) 
 samples collected on roof bolters were 
 over the standard. As previously shown, 
 mines with longwall operations have the 
 highest GM CONC and longwall operators 
 have the highest exposures. However, at 
 the present time there are relatively few 
 longwalls compared to other methods of 
 
 mining so occupations not specific to 
 longwall operation, such as roof bolters 
 and continuous miner operators, account 
 for more samples exceeding the 2.0-mg/m 3 
 standard. 
 
 Table 12 shows the yearly statistics 
 for five dusty occupations: continuous 
 miner helper, longwall jacksetter, long- 
 wall shear-plow operator, and roof 
 bolter. There was a reduction in the 
 GM CONC and the percentage of samples 
 exceeding the 2.0-mg/m 3 standard for the 
 longwall shear-plow operator and a re- 
 duction in the percentage of samples 
 exceeding the standard for the longwall 
 jack setter. Levels for the other three 
 occupations remained essentially constant 
 over the 1981-84 4-yr period. 
 
 n^nm^HMi 
 
TABLE 11. - 1984 coal mine dust data for underground and surface occupations 
 
 Occupation 
 
 Samples 
 
 Concentration, mg/m 
 
 GM GSD 
 
 AM ASD 
 
 >TLV, 
 pet 
 
 Underground: 
 
 Longwall tailgate side 
 
 Longwall jack setter 
 
 Headgate operator 
 
 Auger jack setter, return side 
 
 Continuous miner operator 
 
 Loading machine operator 
 
 Continuous miner helper 
 
 Roof bolter 
 
 Roof bolter helper 
 
 Cutting machine operator 
 
 Utility man 
 
 Shotf irer < 
 
 Auger jack setter, intake 
 
 Section foreman 
 
 Shuttle car operator 
 
 Mobile bridge operator 
 
 Shuttle car operator standard side. 
 
 Coal drill operator 
 
 Scoop car operator , 
 
 Mechanic • 
 
 Motorman , 
 
 Hand loader. ' 
 
 Surface: 
 
 Fine coal plant operator 
 
 Highwall drill operator 
 
 Cleanup man. 
 
 Scalper-screen operator 
 
 Cleaning plant operator 
 
 Laborer 
 
 Refuse truck driver 
 
 Tipple operator 
 
 Mechanic 
 
 Bulldozer operator 
 
 Scraper operator 
 
 Highlif t operator 
 
 Oiler-greaser 
 
 Coal truck driver 
 
 Coal shovel operator 
 
 Crane-dragline operator 
 
 387 
 499 
 136 
 116 
 
 2,579 
 283 
 
 1,405 
 
 3,451 
 629 
 516 
 304 
 174 
 279 
 277 
 757 
 136 
 
 2,123 
 483 
 938 
 181 
 148 
 117 
 
 197 
 817 
 169 
 108 
 216 
 525 
 634 
 375 
 339 
 
 1,651 
 221 
 
 1,565 
 189 
 179 
 107 
 232 
 
 1.66 
 1.50 
 .87 
 .83 
 .77 
 .76 
 .73 
 .69 
 .65 
 .64 
 .64 
 .58 
 .57 
 .55 
 .54 
 .53 
 .51 
 .48 
 .47 
 .44 
 .41 
 .30 
 
 1.00 
 .62 
 .58 
 .58 
 .49 
 .44 
 .38 
 .35 
 .31 
 .30 
 .25 
 .22 
 .22 
 .22 
 .19 
 .17 
 
 1.93 
 1.84 
 2.55 
 4.89 
 2.83 
 2.58 
 2.76 
 2.74 
 2.80 
 2.99 
 2.68 
 2.93 
 3.81 
 2.52 
 2.59 
 3.13 
 2.58 
 2.94 
 2.85 
 2.44 
 3.01 
 2.47 
 
 .85 
 .36 
 .92 
 .67 
 .90 
 .11 
 .61 
 .90 
 .86 
 .49 
 .54 
 .29 
 .30 
 .01 
 .12 
 .14 
 
 2.03 
 
 1.80 
 
 1.30 
 
 2.44 
 
 1.31 
 
 1.15 
 
 1.15 
 
 1.09 
 
 1.02 
 
 1.23 
 
 1.17 
 
 1.00 
 
 1.69 
 
 .83 
 
 .86 
 
 1.03 
 
 .80 
 
 .97 
 
 .78 
 
 .66 
 
 .74 
 
 .47 
 
 1.51 
 1.29 
 1.04 
 .88 
 .88 
 .97 
 .59 
 .64 
 .63 
 .48 
 .43 
 .34 
 .32 
 .29 
 .26 
 .43 
 
 1.45 
 
 1.30 
 
 1.24 
 
 4.17 
 
 2.31 
 
 1.30 
 
 1.31 
 
 1.24 
 
 .97 
 
 3.05 
 
 4.20 
 
 1.28 
 
 5.47 
 
 .99 
 
 1.22 
 
 1.45 
 
 2.00 
 
 3.02 
 
 .99 
 
 .81 
 
 .96 
 
 .50 
 
 1.19 
 
 2.05 
 
 1.67 
 
 .80 
 
 1.50 
 
 3.16 
 
 .61 
 
 .86 
 
 2.19 
 
 .98 
 
 .69 
 
 .43 
 
 .35 
 
 .24 
 
 .28 
 
 3.15 
 
 34.6 
 
 28.7 
 
 18.4 
 
 36.2 
 
 14.2 
 
 12.4 
 
 13.7 
 
 11.9 
 
 12.1 
 
 12.2 
 
 9.1 
 
 10.3 
 
 16.8 
 
 5.4 
 
 4.9 
 
 11.0 
 
 5.6 
 
 6.2 
 
 5.6 
 
 2.8 
 
 6.1 
 
 4.3 
 
 32.0 
 
 17.1 
 
 10.0 
 
 9.3 
 
 6.5 
 
 7.4 
 
 3.3 
 
 6.4 
 
 2.9 
 
 2.0 
 
 3.2 
 
 1.3 
 
 .5 
 
 
 
 
 
 .9 
 
 AM Arithmetic mean. 
 ASD Arithmetic standard deviation. 
 GM Geometric mean. 
 See table A-4 for complete list of 
 
 GSD Geometric 
 TLV Threshold 
 
 standard 
 limit va 
 
 deviation, 
 lue. 
 
 codes, occupations, and samples 
 
 NOTE. — Only occupations with at least 100 
 they are ranked by GM concentration. 
 
 samples are included in this table and 
 
16 
 
 TABLE 12. - Trends in exposure for five underground coal mine occupations 
 
 Occupation 
 
 Continuous miner operator: 
 
 Samples 
 
 AM CONC mg/m 3 
 
 ASD mg/m 3 , 
 
 GM CONC rag/m 3 
 
 GSD rag/m 3 
 
 >TLV pet 
 
 Continuous miner helper: 
 
 Samples 
 
 AM CONC mg/m 3 . 
 
 ASD mg/m 3 
 
 GM CONC mg/m 3 , 
 
 GSD mg/m3, 
 
 > TLV pet 
 
 Longwall jack setter: 
 
 Samples 
 
 AM CONC rag/m 3 , 
 
 ASD mg/m 3 
 
 GM CONC rag/m 3 
 
 GSD rag/m 3 , 
 
 >TLV pet 
 
 Longwall shear-plow operator: 
 
 Samples 
 
 AM CONC rag/m3 , 
 
 ASD rag/m 3 
 
 GM CONC mg/m 3 , 
 
 GSD mg/m 3 , 
 
 >TLV pet. 
 
 Roof bolter: 
 
 Samples 
 
 AM CONC . rag/m 3 , 
 
 ASD rag/ra 3 , 
 
 GM CONC mg/m 3 . 
 
 GSD mg/m 3 . 
 
 >TLV pet, 
 
 AM CONC Arithmetic mean concentration. 
 
 ASD Arithmetic standard deviation. 
 
 GM CONC Geometric mean concentration. 
 
 GSD Geometric mean standard deviation. 
 
 TLV Threshold limit value. 
 
 1981 
 
 1982 
 
 1983 
 
 1984 
 
 2,196 
 1.30 
 2.20 
 0.82 
 2.63 
 14.6 
 
 1,349 
 1.14 
 1.16 
 0.77 
 2.61 
 12.7 
 
 269 
 1.72 
 1.30 
 1.35 
 2.10 
 32.0 
 
 188 
 2.60 
 2.49 
 1.88 
 2.30 
 47.9 
 
 3,382 
 
 1.21 
 2.01 
 0.76 
 2.70 
 13.3 
 
 2,484 
 1.26 
 2.45 
 0.82 
 2.52 
 13.0 
 
 1,512 
 1.12 
 1.06 
 0.78 
 2.45 
 10.7 
 
 296 
 
 1.79 
 1.39 
 1.43 
 2.00 
 40.4 
 
 213 
 2.16 
 1.53 
 1.74 
 1.97 
 41.3 
 
 3,464 
 1.24 
 2.43 
 0.77 
 2.67 
 13.0 
 
 2,445 
 1.14 
 1.21 
 0.73 
 2.70 
 12.4 
 
 1,413 
 1.01 
 1.10 
 0.66 
 2.67 
 9.5 
 
 414 
 1.79 
 1.65 
 1.40 
 2.00 
 27.5 
 
 328 
 1.95 
 1.35 
 1.57 
 1.97 
 34.4 
 
 3,624 
 1.00 
 1.18 
 0.63 
 2.75 
 9.6 
 
 2,579 
 1.31 
 2.31 
 0.77 
 2.83 
 14.2 
 
 1,405 
 1.15 
 1.31 
 0.73 
 2.76 
 13.7 
 
 499 
 1.80 
 1.30 
 1.50 
 1.84 
 28.7 
 
 387 
 2.03 
 1.45 
 1.66 
 1.93 
 34.6 
 
 3,451 
 1.09 
 1.24 
 0.69 
 2.74 
 11.9 
 
SUMMARY AND CONCLUSIONS 
 
 The MIDAS data base stores environ- 
 mental data collected from coal mines and 
 metal and nonmetal mines or mills. The 
 metal and nonmetal data were collected by 
 MSHA inspectors from 1974 to the present, 
 whereas the coal respirable dust data 
 were collected by both coal mine opera- 
 tors and MSHA inspectors from 1970 to the 
 present. There are about 450,000 records 
 from metal and nonmetal mines and mills 
 and 6.5 million records from coal mines 
 in the data base. 
 
 The data base is split into two subsys- 
 tems — metal-nonmetal and coal. The soft- 
 ware used to analyze each subsystem is 
 similar but not identical because of the 
 different record formats and different 
 coding systems used in each. The soft- 
 ware is user friendly, menu driven, and 
 requires minimum knowledge of the central 
 computer operating system. Reports are 
 in the form of tables and graphs. 
 
 This report also describes results from 
 analyses of the metal and nonmetal 
 respirable quartz (RQ) data and the coal 
 mine respirable dust data gathered by 
 MSHA inspectors from 1981 through 1984. 
 Major findings of these analyses follow. 
 
 1. There was a reduction in the per- 
 centage of samples exceeding the RQ stan- 
 dard in metal and nonmetal mines from 
 1974 through 1979, and a slight increase 
 from 14.7 to 17.2 pet from 1980 through 
 1984. This increase was accompanied by 
 the collection of fewer samples by MSHA 
 and policy changes caused by the passage 
 of the 1977 act and changes in the 1982 
 appropriation. Overall, 9,000 RQ samples 
 (18 pet) exceeded the RQ standard. 
 
 2. The use of respiratory protec- 
 tion among metal and nonmetal mine work- 
 ers sampled by MSHA increased from 18 pet 
 in 1974 to 47 pet in 1984. Occupa- 
 tions showing the greatest increase in 
 the use of respiratory protection were 
 jack stoper driller (20.4 pet increase), 
 
 pneumatic drill operator (20.3 pet in- 
 crease), and flotation operator (19.7 pet 
 increase). 
 
 3. Baggers in nonmetal mills had the 
 highest percent of samples exceeding the 
 RQ standard, but showed the m greatest 
 overall improvement with an 11-pct reduc- 
 tion in overexposure from the 1974-79 
 to 1980-84 period. Flotation operator, 
 truck driver, and jack stoper driller 
 occupations also reduced the percentage 
 of samples over the standard by 10 pet or 
 more for the same time periods. Three 
 occupations, stope miner, motorman, and 
 laborer, showed slight increases in the 
 percent of overexposures for these two 
 time periods. 
 
 4. Analysis of metal and nonmetal RQ 
 data collected by MSHA inspectors showed 
 that the net effect of changing the cur- 
 rent standard from a formula based upon 
 the percentage of quartz in the sample to 
 a standard of 100 ug/m 3 of respirable 
 quartz would be 4 pet fewer samples would 
 exceed the standard. 
 
 5. Analysis of coal mine respirable 
 dust data showed that between 1981 and 
 1984, 10 to 12 pet of the samples ex- 
 ceeded the 2.0-mg/m 3 standard while the 
 geometric mean concentration (GM CONC) 
 fluctuated between 0.59 and 0.69 mg/m 3 . 
 On average, about 1,800 samples exceeded 
 the standard each year. However, far 
 fewer mines were out of compliance be- 
 cause compliance is based on the arithme- 
 tic average of five samples exceeding the 
 2.0-mg/m 3 standard. 
 
 6. Designated occupation concentra- 
 tions are generally higher than the non- 
 designated occupation values at mines 
 using longwall, continuous rippers, or 
 augering as the mining method. 
 
 7. Mines with longwall plows or shears 
 have the highest GM CONC (1.64 and 1.29 
 mg/m 3 ) and the greatest percentage of 
 samples exceeding the 2.0-mg/m 3 standard 
 
(43.7 and 25.2 pet). However, many more 
 samples (10,946) were recorded at mines 
 using continuous rippers with 10.9 pet of 
 the samples exceeding the 2.0-mg/m 3 limit 
 with a GM CONC of 0.66 mg/m 5 . The dust 
 concentrations were greater at mines with 
 longwall operations but there were nearly 
 nine times more continuous ripper oper- 
 ations with samples having dust concen- 
 trations greater than the Federal 
 standard. 
 
 8. Coal mine occupations with the 
 greatest percent of samples exceeding the 
 2.0-mg/m 3 standard were auger jack set- 
 ter, longwall shear-plow operator, fine 
 coal plant operator, and longwall jack 
 setter. Occupations with the greatest 
 number of samples exceeding the 2.0-mg/m 5 
 standard were continuous miner operator 
 and helper, roof bolter, and highwall 
 drill operator. 
 
 REFERENCES 
 
 1. National Materials Advisory Board. 
 Measurement and Control of Respirable 
 Dust in Mines. Natl. Acad. Sci. , Wash- 
 ington, DC, NMAB-363, 1980, 405 pp. 
 
 2. U.S. Congress. Federal Mine Safety 
 and Health Act of 1977. Public Law 91- 
 173, as amended by Public Law 95-164, 
 Nov. 9, 1977, 83 Stat. 803. 
 
 3. U.S. Code of Federal Regulations. 
 Title 30 — Mineral Resources; Chapter 1 — 
 Mine Safety and Health Administration, 
 Department of Labor; July 1, 1984. 
 
 4. American Conference of Governmental 
 Industrial Hygienists (Cincinnati, OH). 
 TLV's — Threshold Limit Values for Chemi- 
 cal Substances in Workroom Air Adopted by 
 the ACGIH in 1973. 1973, 54 pp. 
 
 5. Watts, W. F., Jr., R. L. Johnson, 
 D. J. Donaven, and D. R. Parker. An 
 Introduction to the Mine Inspection 
 Data Analysis System (MIDAS). BuMines 
 IC 8859, 1981, 41 pp. 
 
 6. Sutton, G. W. , G. W. Weeras, L. A. 
 Schutz, and G. D. Trabant. Summary Re- 
 port of the Environmental Results of the 
 MSHA and NIOSH Silica/Diesel Exhaust 
 Study. Paper in Industrial Hygiene for 
 Mining and Tunneling. Proceedings of a 
 Topical Symposium sponsored by ACGIH, 
 November 6 and 7, 1978, Denver, CO. 
 ACGIH, 1979, pp. 109-117. 
 
 7. Watts, W. F., D. R. Parker, and 
 J. E. Small-Johnson. Gas and Dust Con- 
 centrations at 18 Underground, Diesel- 
 ized, Noncoal Mines. Pres. at Am. Ind. 
 Hyg. Assoc. Meet., May 19-24, 1985, 
 
 Las Vegas, NV, 17 pp.; available from 
 W. F. Watts, Jr., BuMines, Minneapolis, 
 MN. 
 
 8. Dixon, W. J. (ed. ). BMDP Statis- 
 tical Software. Univ. CA Press, 1985, 
 734 pp. 
 
 9. U.S. Congress. The Federal Mine 
 Safety and Health Act of 1977. Public 
 Law 91-173, as amended by Public Law 95- 
 164, Nov. 9, 1977, 91 Stat. 1291 and 
 1299. 
 
 10. Treaftis, H. N. , A. J. Gero, P. M. 
 Kacsmar, and T. F. Tomb. Comparison of 
 Mass Concentrations Determined With Per- 
 sonal Respirable Coal Mine Dust Samplers 
 Operating at 1.2 Liters Per Minute and 
 the Casella 113A Gravimetric Sampler 
 (MRE). Am. Ind. Hyg. Assoc J. , v. 45, 
 No. 12, 1984, pp. 826-832. 
 
 11. American Conference of Governmen- 
 tal Industrial Hygienists (Cincinnati, 
 OH). Documentation of the Threshold 
 Limit Values. 4th ed. , 1980, pp. 364- 
 365. 
 
 12. U.S. Mine Safety and Health Ad- 
 ministration. Preproposal Draft Air 
 Quality Standards. 1983, 61 pp. ; avail- 
 able from Health Div. for Metal and Non- 
 metal Safety and Health, MSHA, Arlington, 
 VA. 
 
 13. Watts, W. F., Jr., D. R. Parker, 
 R. L. Johnson, and K. L. Jensen. Analy- 
 sis of Data on Respirable Quartz Dust 
 Samples Collected in Metal and Nonmetal 
 Mines and Mills. BuMines IC 8967, 1984, 
 28 pp. 
 
APPENDIX. --MSHA SAMPLING CODES, DESCRIPTORS, AND SELECTED DATA 
 TABLE A-l. - Metal and nonmetal occupation codes 
 
 iy 
 
 Code Occupation 
 
 28. . Scoop-tram 
 
 29. . Mucking machine , 
 
 30. . Slusher 
 
 32. . Brattice 
 
 34. . Diamond drill , 
 
 35.. Continuous miner helper..... 
 
 36.. Continuous miner operator.., 
 
 37.. Cutting machine helper , 
 
 38.. Cutting machine operator..., 
 
 39.. Hand loader , 
 
 41.. Jack setter , 
 
 43.. Gather arm loader 
 
 45.. Hand and chute blast 
 
 46.. Rock and roof bolter 
 
 48.. Roof bolter mounted 
 
 53. . Utility man , 
 
 57.. Stope miner , 
 
 58.. Drift miner , 
 
 59. . Raise miner , 
 
 79. . Crusher , 
 
 134. Jet-piercer channel , 
 
 154. Belt cleanup , 
 
 179. Ball and rod mill , 
 
 216. Track gang , 
 
 234. Jet piercer drill , 
 
 261. Battery station , 
 
 279. Hammer mill 
 
 331. Clam-shell 
 
 334. Wagon drill , 
 
 342. Bit grinding and sharpening, 
 
 344. Car shakeout 
 
 352. Iron and metal work 
 
 367. Shovel operator 
 
 368. Bulldozer 
 
 372. Barge and dredge 
 
 375. Road grader 
 
 376. Trucker 
 
 378. Mobile crane 
 
 379. Dryer and kiln 
 
 385. Lampman 
 
 387. Rotary bucket excavation... 
 
 588. Sizing and washing 
 
 601. Conveyor belt 
 
 602. Electrician 
 
 603. Electrician helper 
 
 604. Mechanic 
 
 607 . Jackhammer 
 
 608. Mason 
 
 609. I Supply man nipper 
 
 Samples 
 
 Code 
 
 Occupation Samples 
 
 Belt vulcanizer 
 
 Cleanup man 4,712 
 
 Sampler 27 
 
 Laborer and bullgang.... 571 
 
 Greaser and oiler 61 
 
 Welder 159 
 
 Dump operator 192 
 
 Surveyor 
 
 Rotary drill 74 
 
 Administrator 419 
 
 Machinist 
 
 Shaft miner 3 
 
 Tractor operator 11 
 
 Puller and truck loader. 138 
 
 Leaching operations 14 
 
 Warehouse man 376 
 
 Dragline 11 
 
 Flotation 657 
 
 Scraper-loader 46 
 
 Shotcrete man 
 
 Ventilation crew 1 
 
 Ground control 98 
 
 Cement operations 223 
 
 Grizzly tender 9 
 
 Load, haul, dump cycle.. 123 
 
 Pneumatic drill 1,049 
 
 Hand trammer 4 
 
 Hand scaling 1 
 
 Diesel shuttle 10 
 
 Raise borer 
 
 Shaft repair 
 
 Dry sandfill 14 
 
 Wet sandfill 2 
 
 Backhoe 2 
 
 Pelletizing 350 
 
 Front-end loader 13,463 
 
 Scalper screen 19 
 
 Forklift 28 
 
 Top skip and tipple 5 
 
 Weight and scale 8 
 
 Carpenter 1 
 
 Yard engine 3 
 
 Stone and rock saw 326 
 
 Janitor 2 
 
 Salvage crew 
 
 Aerial tram 1 
 
 Churn drill 4 
 
 Engineer 263 
 
 Hydrating plant 4 
 
 19 
 
 94 
 
 290 
 
 
 
 76 
 
 3 
 
 66 
 
 
 
 1 
 
 2 
 
 2 
 
 2 
 
 
 
 96 
 
 2 
 
 125 
 
 1,248 
 
 80 
 
 7 
 
 8,342 
 
 110 
 
 21 
 
 1,523 
 
 46 
 
 6 
 
 
 
 8 
 
 3 
 
 1,634 
 
 
 
 6 
 
 1 
 
 97 
 
 1,122 
 
 64 
 
 9 
 
 1,259 
 
 11 
 
 1,982 
 
 
 
 1 
 
 1,751 
 
 25 
 
 7 
 
 
 
 1,691 
 
 112 
 
 
 
 6 
 
 612. 
 613. 
 614. 
 616. 
 618. 
 619. 
 622. 
 623. 
 634. 
 649. 
 660. 
 663. 
 668. 
 669. 
 673. 
 674. 
 678. 
 679. 
 682. 
 706. 
 708. 
 710. 
 716. 
 726. 
 728. 
 734. 
 739. 
 747. 
 750. 
 759. 
 763. 
 765. 
 766. 
 778. 
 779. 
 782. 
 388. 
 389. 
 392. 
 393. 
 394. 
 397. 
 399. 
 413. 
 416. 
 420. 
 434. 
 456. 
 479. 
 
20 
 
 TABLE A-l. - Metal and nonmetal occupation codes — Continued 
 
 Code 
 
 Occupation 
 
 Dry screen plant.., 
 Building repair..., 
 Lab technician. 
 Tamping machine..., 
 Jack stoper drill.. 
 Slurry and mix. 
 
 Plumber , 
 
 Powder gang , 
 
 Bobcat , 
 
 Drill helper , 
 
 Mechanical scaling, 
 
 Samples 
 
 Code 
 
 Occupation 
 
 Ramcar , 
 
 Overhead crane 
 
 Bagging and packing..., 
 
 Painter 
 
 Cager 
 
 Hoist , 
 
 Skip tender 
 
 Jumbo percussive drill, 
 
 Electic shuttle 
 
 Trip rider swamper. 
 Motorman 
 
 Samples 
 
 488. 
 513. 
 514. 
 516. 
 534. 
 579. 
 804. 
 807. 
 825. 
 833. 
 847. 
 
 233 
 
 850. 
 
 29 
 
 878. 
 
 58 
 
 879. 
 
 
 
 894. 
 
 675 
 
 920. 
 
 109 
 
 921. 
 
 17 
 
 930. 
 
 36 
 
 934. 
 
 11 
 
 950. 
 
 15 
 
 962. 
 
 4 
 
 969. 
 
 
 
 6 
 
 2,745 
 
 
 
 4 
 
 148 
 
 17 
 
 50 
 
 
 
 
 
 1,087 
 
 TABLE A-2. - Metal and nonmetal location codes 
 
 Code 
 
 Location 
 
 Underground: 
 
 1 Active mining. 
 
 3 Exploration and development , 
 
 5 Travel and haul way. 
 
 7 Shaft and station. 
 
 9 Hoistroom. 
 
 11 Ore processing. 
 
 13 Ore transfer point. 
 
 15 Shops. 
 
 17 Office and storeroom. 
 
 19 General. 
 
 21 Construction. 
 
 Surface: 
 
 31 Active mining. 
 
 33 Exploration and development, 
 
 35 Roads. 
 
 39 Tailings pond. 
 
 41 Ore processing. 
 
 43 Ore transfer point. 
 
 45 Shops. 
 
 47 Office and storage. 
 
 Code 
 
 Location 
 
 Surface — Con. 
 
 49 General. 
 
 51 Construction. 
 
 Mill: 
 
 61 Crushing. 
 
 63 Grinding. 
 
 65 Washing and screening. 
 
 67 Dry screening. 
 
 69 Drying and roasting. 
 
 71 Ore transfer point. 
 
 73 Shops. 
 
 75 Office and storage. 
 
 77 General. 
 
 79 Flotation and reagents, 
 
 81 Pelletizing. 
 
 83 Bagging and packing. 
 
 85 Construction. 
 
 Miscellaneous: 
 
 37 Dredges and barges . 
 
 99 Anywhere. 
 
21 
 
 TABLE A-3. - Metal and nonmetal SIC codes 
 
 Code 
 
 Commodity 
 
 Samples' 
 
 Code 
 
 Commodity 
 
 NONMETAL— Continued: 
 
 Phosphate rock , 
 
 Salt rock , 
 
 Sulfur , 
 
 Chemical fertilizer...., 
 
 Lithium , 
 
 Pigment minerals , 
 
 Pyrites , 
 
 Strontium , 
 
 Gypsum , 
 
 Talc and pyrophylite. . . , 
 
 Nonmetal minerals 
 
 Asbestos 
 
 Gems tones , 
 
 Gilsonite 
 
 Mica 
 
 Peat , 
 
 Perlite , 
 
 Pumi ce , 
 
 Vermiculite , 
 
 Industrial chemicals..., 
 
 Alumina , 
 
 Evaporated salt , 
 
 Brine salt , 
 
 Leonardite , 
 
 STONE 
 
 Other dimension stone.., 
 
 Dimension granite , 
 
 Dimension limestone...., 
 
 Dimension marble , 
 
 Dimension sandstone...., 
 
 Dimension slate 
 
 Dimension traprock 
 
 Crushed limestone 
 
 Crushed granite , 
 
 Crushed stone 
 
 Crushed marble , 
 
 Crushed sandstone 
 
 Crushed slate , 
 
 Crushed traprock 
 
 Cement 
 
 Lime 
 
 SAND AND GRAVEL 
 
 Sand and gravel 
 
 UNKNOWN 
 
 Unknown. 
 
 Samples' 
 
 METAL 
 
 10110 
 10210 
 10310 
 10410 
 10440 
 10510 
 10610 
 10611 
 10612 
 10613 
 10614 
 10615 
 10616 
 10617 
 10920 
 10940 
 10941 
 10942 
 10990 
 10991 
 10992 
 10993 
 10994 
 10995 
 10996 
 10997 
 
 13111 
 13112 
 14530 
 14550 
 14590 
 14591 
 14592 
 14593 
 14594 
 14595 
 14596 
 14720 
 14730 
 14740 
 14741 
 14742 
 14743 
 14744 
 
 Iron 
 
 Copper 
 
 Lead and zinc 
 
 Gold 
 
 Silver 
 
 Aluminum 
 
 Ferroalloy 
 
 Chromite 
 
 Cobalt 
 
 Columbium, tantalum.... 
 
 Manganese 
 
 Molybdenum 
 
 Ni eke 1 
 
 Tungsten 
 
 Mercury 
 
 Uranium and vanadium. . . 
 
 Uranium 
 
 Vanadium 
 
 Other metal 
 
 Antimony 
 
 Beryl 
 
 Platinum 
 
 Rare earths 
 
 Tin 
 
 Titanium 
 
 Zircon 
 
 NONMETAL 
 
 Oil shale 
 
 Oil sand 
 
 Fire clay 
 
 Common clay 
 
 Ceramic clay 
 
 Aplite 
 
 Brucite 
 
 Feldspar. 
 
 Kyanite , 
 
 Magnesite 
 
 Common shale , 
 
 Barite 
 
 Fluorspar , 
 
 Potash, soda, borate. 
 
 Boron , 
 
 Potash , 
 
 Trona , 
 
 Sodium compounds...., 
 
 2,593 
 
 2,240 
 
 1,044 
 
 1,150 
 
 756 
 
 8 
 
 
 
 
 
 5 
 
 
 
 20 
 
 600 
 
 6 
 
 53 
 
 11 
 
 275 
 
 1,158 
 
 6 
 
 34 
 
 37 
 
 4 
 
 
 
 23 
 
 1 
 
 8 
 
 
 
 102 
 
 
 
 784 
 
 2,792 
 
 13 
 
 7 
 
 
 
 252 
 
 27 
 
 
 
 326 
 
 226 
 
 142 
 
 2 
 
 21 
 
 2 
 
 13 
 
 
 
 14750 
 14760 
 14770 
 14790 
 14791 
 14792 
 14793 
 14794 
 14920 
 14960 
 14990 
 14991 
 14992 
 14993 
 14994 
 14995 
 14996 
 14887 
 14998 
 28190 
 28191 
 28991 
 28992 
 29900 
 
 14110 
 14111 
 14112 
 14113 
 14114 
 14115 
 14116 
 14220 
 14230 
 14290 
 14291 
 14292 
 14293 
 14294 
 32410 
 32740 
 
 14410 
 
 531 
 
 16 
 
 
 
 
 
 113 
 
 4 
 
 
 
 
 
 241 
 
 183 
 
 881 
 
 3 
 
 7 
 
 2 
 
 146 
 
 
 
 29 
 
 37 
 
 15 
 
 
 
 10 
 
 
 
 
 
 50 
 
 57 
 
 1,113 
 
 259 
 
 35 
 
 434 
 
 260 
 
 58 
 
 13,054 
 
 3,206 
 
 689 
 
 18 
 
 3,421 
 
 94 
 
 869 
 
 1,232 
 
 323 
 
 8 ,309 
 
 
 
 68 
 
 For respirable quartz. 
 
22 
 
 TABLE A-4. - Occupation codes most frequently used in 1984 by MSHA coal 
 mine inspectors 
 
 Code 
 
 Occupation 
 
 Samples 
 
 Code 
 
 Occupation 
 
 Samples 
 
 UNDERGROUND FACE 
 
 UNDERGROUND FACE— Continued 
 
 1... 
 
 4... 
 7... 
 10.. 
 
 16.. 
 34.. 
 35.. 
 36.. 
 37.. 
 38.. 
 39.. 
 40.. 
 41.. 
 43.. 
 44.. 
 46.. 
 47.. 
 48.. 
 49.. 
 50.. 
 
 52.. 
 53.. 
 54.. 
 55.. 
 
 72.. 
 
 T 
 
 Belt man , 
 
 Mechanic. *. , 
 
 Shotf irer , 
 
 Auger jack setter (intake 
 
 side) , 
 
 Laborer , 
 
 Coal drill operator 
 
 Continuous miner helper.., 
 Continuous miner operator, 
 Cutting machine helper. . . , 
 Cutting machine operator., 
 
 Hand loader , 
 
 Headgate operator , 
 
 Longwall jack setter , 
 
 Loading machine operator.. 
 Longwall (tailgate side)., 
 
 Roof bolter , 
 
 Roof bolter helper , 
 
 Roof bolter (return side), 
 
 Section foreman , 
 
 Shuttle car operator 
 
 (standard side) , 
 
 Tailgate operator , 
 
 Utiltity man , 
 
 Scoop car operator , 
 
 Auger jack setter (return 
 
 side) , 
 
 Mobile bridge operator..., 
 
 57 
 181 
 
 174 
 
 279 
 
 63 
 
 483 
 
 1,405 
 
 2,579 
 
 96 
 
 516 
 
 117 
 
 136 
 
 499 
 
 283 
 
 387 
 
 3,451 
 
 629 
 
 78 
 
 277 
 
 2,123 
 
 71 
 
 304 
 
 938 
 
 116 
 136 
 
 73.. 
 
 74.. 
 
 302, 
 304. 
 310, 
 313. 
 314. 
 316. 
 318. 
 319, 
 367, 
 368, 
 373, 
 374. 
 375. 
 376. 
 378. 
 380. 
 382. 
 383. 
 384. 
 386. 
 388. 
 392. 
 999. 
 
 Shuttle car operator (off 
 
 standard) 
 
 Motorman 
 
 SURFACE 
 
 Electrician 
 
 Mechanic 
 
 Scraper operator. 
 
 Cleanup man 
 
 Coal sampler 
 
 Laborer 
 
 Oiler-greaser 
 
 Shop welder 
 
 Coal shovel operator 
 
 Bulldozer operator 
 
 Car dropper 
 
 Cleaning plant operator.. 
 
 Road grader operator 
 
 Coal truck driver 
 
 Crane-dragline operator.. 
 Fine coal plant operator. 
 
 Highlift operator 
 
 Driller highwall helper.. 
 Highwall drill operator.. 
 
 Refuse truck driver 
 
 Scalper-screen operator.. 
 
 Tipple operator 
 
 Not designated 
 
 757 
 148 
 
 87 
 339 
 221 
 169 
 
 74 
 525 
 189 
 
 91 
 
 107 
 
 1,651 
 
 92 
 216 
 
 79 
 
 179 
 
 232 
 
 197 
 
 1,565 
 
 57 
 817 
 634 
 108 
 375 
 1,335 
 
 Respirable coal dust. 
 
 TABLE A-5. - MSHA coal mine codes for mine type 
 
 Code Mine type 
 
 1970-80: 
 
 Surface. 
 
 1 Development. 
 
 2 Retreat. 
 
 Code 
 
 Mine type 
 
 Post-1980: 
 
 A Surface. 
 
 B Underground. 
 
23 
 
 TABLE A-6. - MSHA coal mine codes for sample type 
 
 Code 
 
 Sample type 
 
 1970-80 inspector and operator: 
 
 Surface. 
 
 1 High risk. 
 
 2 Intake air. 
 
 3 Non-high risk. 
 
 4 Nonf ace. 
 
 5 Part 90 miner. 
 
 Post-1980 inspector: 
 
 1 Designated occupation. 
 
 2 Nondesignated occupation, 
 
 3 Designated area. 
 
 4 Designated work position. 
 
 Code 
 
 Sample type 
 
 Post-1980 inspector — Continued 
 
 5 Part 90 miner. 
 
 6 Nondesignated area. 
 
 7 Intake air. 
 
 8 Nondesignated work position. 
 
 Post-1980 operator: 
 
 1 Mechanized mining unit. 
 
 2 Nondesignated occupation. 
 
 3 Designated area. 
 
 4 Designated work position. 
 
 5 Part 90 miner. 
 
 TABLE A-7. - MSHA coal mine codes for mining method 
 
 Code Mining method 
 
 1970-80: 
 
 1 Continuous. 
 
 2 Conventional. 
 
 3 Longwall. 
 
 4 Other. 
 
 5 Surface. 
 
 Post-1980: 
 
 A Longwall shear. 
 
 B Longwall plow. 
 
 C Continuous ripper. 
 
 D Continuous bore. 
 
 E Continuous auger. 
 
 Code 
 
 Mining method 
 
 Post-1980 — Continued 
 
 F Continuous shortwall. 
 
 G Conventional with cutting 
 
 machine. 
 
 H Scoop with cutting machine. 
 
 I Scoop shoot off solids. 
 
 J Conventional shoot with loading 
 
 machine. 
 
 K Hand load cutting machine. 
 
 L Hand load shoot off solids. 
 
 M Hand load anthracite. 
 
 N Other (surface). 
 
 TABLE A-8. - Percentage of metal and nonmetal miners wearing respirators 
 
 Occupation 
 
 1974-79 
 
 1980-84 
 
 Change 
 
 Occupation 
 
 1974-79 
 
 1980-84 
 
 Change 
 
 Jack stoper drill. . 
 Pneumatic drill.... 
 Flotation operator. 
 
 38.3 
 38.7 
 30.3 
 30.4 
 36.9 
 45.8 
 26.9 
 33.5 
 45.4 
 
 58.7 
 59.0 
 50.0 
 49.2 
 55.2 
 61.6 
 41.9 
 48.3 
 59.9 
 
 20.4 
 20.3 
 19.7 
 18.8 
 18.3 
 15.8 
 15.0 
 14.8 
 14.5 
 
 
 25.9 
 32.4 
 30.7 
 60.0 
 21.2 
 36.9 
 18.6 
 42.3 
 
 39.9 
 46.0 
 44.2 
 71.4 
 31.6 
 45.5 
 26.4 
 47.5 
 
 14.0 
 
 Crusher worker. . . . 
 
 13.6 
 13.5 
 
 
 11.4 
 
 General cleanup.... 
 Ball and rod mill.. 
 
 Front-end loader.. 
 Sizing and washing 
 
 10.4 
 8.6 
 7.8 
 5.2 
 
 
 
 35.0 
 
 49.2 
 
 14.2 
 
 15087 21f 
 
 INT.-BU.OF MINES,PGH.,PA. 28408 
 
U.S. Department of the Interior 
 Bureau of Mines— Prod, and Oistr. 
 Cochrans Mill Road 
 P.O. Box 18070 
 Pittsburgh. Pa. 15236 
 
 OFRCIALSUSINESS 
 PENALTY FOR PRIVATE USE, S300 
 
 J Do not wish to receive this 
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 73 Address change. Please 
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