IC 9492 

INFORMATION CIRCULAR/2006 

Equipment Noise and Worker Exposure 

in the Coal Mining Industry 

Department of Health and Human Services 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health 
Information Circular 9492 

Equipment Noise and Worker Exposure 

in the Coal Mining Industry 

By Eric R. Bauer, Ph.D., Daniel R. Babich, and Jeffrey R. Vipperman, Ph.D. 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Public Health Service 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health
 
 

Pittsburgh Research Laboratory 

Pittsburgh, PA 

December 2006 

 

This document is in the public domain and may be freely copied 

or reprinted. 

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Occupational Safety and Health (NIOSH). In addition, citations to Web sites external to NIOSH 

do not constitute NIOSH endorsement of the sponsoring organizations or their programs or 

products. Furthermore, NIOSH is not responsible for the content of these Web sites. 

ORDERING INFORMATION 

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Telephone: 1–800–35–NIOSH (1–800–356–4674) 

Fax: 513–533–8573 

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or visit the NIOSH Web site at www.cdc.gov/niosh 

DHHS (NIOSH) Publication No. 2007–105 

December 2006 

SAFER • HEALTHIER • PEOPLETM 
CONTENTS
 

Page 

Abstract........................................................................................................................................................ 1 

Glossary ....................................................................................................................................................... 2 

Introduction.................................................................................................................................................. 3 

Scope of research ......................................................................................................................................... 5 

Instrumentation and data collection............................................................................................................. 6 

Results.......................................................................................................................................................... 9 

 Underground coal...................................................................................................................................10 

 Worker dose.....................................................................................................................................11 

 Task observations.............................................................................................................................11 

 Equipment noise...............................................................................................................................12 

 Surface coal............................................................................................................................................15 

 Worker dose.....................................................................................................................................16 

 Task observations.............................................................................................................................17 

 Dragline noise ..................................................................................................................................19 

Coal preparation plants ..........................................................................................................................24 

 Worker dose.....................................................................................................................................24 

 Task observations.............................................................................................................................26 

 Area sound levels.............................................................................................................................26 

Implications for exposure reduction ............................................................................................................29 

Summary ......................................................................................................................................................30 

Acknowledgments........................................................................................................................................31 

References....................................................................................................................................................31 

Appendix A.—Cumulative dose plots: underground coal..........................................................................33 

Appendix B.—Equipment noise profiles: underground coal......................................................................39
 

Appendix C.—Cumulative dose plots: surface coal ...................................................................................49 

Appendix D.—Equipment noise profiles: surface coal ..............................................................................55 

Appendix E.—Cumulative dose plots: coal preparation plants..................................................................62
 
 

Appendix F.—Area noise profiles: coal preparation plants........................................................................66 

ILLUSTRATIONS 

1. Hearing loss as a function of miners’ age.................................................................................... 4 

2. Hearing impairment in coal miners, metal/nonmetal miners, and nonoccupationally 

 exposed males ......................................................................................................................... 4 

3. Locations of noise surveys........................................................................................................... 6 

4. Quest Q–400 dosimeter and microphone placement ................................................................... 8 

5. Paper method of task observation................................................................................................ 8 

6. Task observation using a PDA..................................................................................................... 8 

7. Mounted Quest 2900 SLM and Brüel & Kjær 2260 Investigator................................................ 9 

8. Cumulative dose plot for roof bolter operator, with task observations........................................13 

9. Sound profile plot of sound levels for a longwall shearer ...........................................................14 

10. Sound profile of sound levels around a dual-boom roof bolter ...................................................14 

11. Leq(A) sound levels around a Schroeder model 271 auxiliary fan ...............................................15 
ILLUSTRATIONS–Continued 

Page 

12. Cumulative dose plot for a dragline oiler, Marion 8750 dragline................................................18 

13. Cumulative dose plot for oiler when dragline is not operating....................................................18 

14. Example of sound level measurement locations in a dragline.....................................................20 

15. Motor-generator sets in back of dragline.....................................................................................20 

16. Example of hoist and/or drag motors...........................................................................................21 

17. Swing motor and gear ..................................................................................................................21 

18. Page 736 dragline.........................................................................................................................21 

19. Sound profile plot for a Page 736 dragline ..................................................................................22 

20. Bucyrus-Erie 1570W dragline .....................................................................................................22 

21. Sound profile plot for a Bucyrus-Erie 1570W dragline...............................................................23 

22. Marion 8050 dragline...................................................................................................................23 

23. Sound profile plot for a Marion 8050 dragline ............................................................................24 

24. Typical coal preparation plant construction.................................................................................26 

25. Cumulative dose plot for stationary equipment operator.............................................................27 

26. Cumulative dose plot for prep plant mechanic ............................................................................27
 
 

27. Example of a low-sound-level preparation plant floor ................................................................28 

28. Example of a high-sound-level preparation plant floor ...............................................................28 

29. Example of a variable-sound-level preparation plant floor .........................................................29 

A–1. Cumulative dose plot for a miner/bolter operator........................................................................33 

A–2. Cumulative dose plot for right-side roof bolter operator.............................................................34 

A–3. Cumulative dose plot for left-side roof bolter operator ...............................................................34 

A–4. Cumulative dose plot for continuous mining machine operator..................................................35 

A–5. Cumulative dose plot for shuttle car operator..............................................................................35 

A–6. Cumulative dose plot for continuous mining machine helper .....................................................36 

A–7. Cumulative dose plot for center bolter operator ..........................................................................36 

A–8. Cumulative dose plot for head shearer operator ..........................................................................37 

A–9. Cumulative dose plot for tail shearer operator.............................................................................37 

A–10. Cumulative dose plot for stageloader (headgate) operator ..........................................................38 

B–1. Leq(A) sound levels around a Joy miner/bolter during mining.....................................................40 

B–2. Leq(A) sound levels around a Joy miner/bolter during bolting cycle ...........................................41 

B–3. Leq(A) sound levels around an Alpine miner/bolter during mining only .....................................42 

B–4. Leq(A) sound levels around an Alpine miner/bolter during mining and bolting ..........................42 

B–5. Leq(A) sound levels around a Joy model 14BU10 loading machine ............................................43 

B–6. Leq(A) sound levels around a Fletcher model DR–15–E single-boom roof bolting machine ......44 

B–7. Leq(A) sound levels around a McLanahan HV–50 feeder-breaker...............................................45 

B–8. Leq(A) sound levels around a Stamler model BF–14A–1Z–530 feeder-breaker..........................45 

B–9. Leq(A) sound levels around Spendrup Dual 50 and Dual 60 hp fans ...........................................46 

B–10. Leq(A) sound levels near shearer while cutting from tail to head.................................................47 

B–11. Leq(A) sound levels around a longwall stageloader......................................................................47 

B–12. Leq(A) sound levels around longwall hydraulics..........................................................................48 

C–1. Cumulative dose plot for Marion 8050 dragline oiler .................................................................49 

C–2. Cumulative dose plot for Bucyrus-Erie 1260W dragline oiler ....................................................50 

C–3. Cumulative dose plot for Bucyrus-Erie 2570W dragline oiler ....................................................50 
ILLUSTRATIONS–Continued 

Page 

C–4. Cumulative dose plot for Marion 8200 dragline oiler .................................................................51 

C–5. Cumulative dose plot for Marion 7800 dragline oiler .................................................................51 

C–6. Cumulative dose plot for Page 736 dragline oiler/groundsman...................................................52 

C–7. Cumulative dose plot for Bucyrus-Erie 1570W dragline oiler ....................................................52 

C–8. Cumulative dose plot for Marion 8750 dragline oiler .................................................................53 

C–9. Cumulative dose plot for Bucyrus-Erie 1370W dragline oiler ....................................................53 

C–10. Cumulative dose plot for welder performing air arcing...............................................................54 

D–1. Leq(A) sound levels in house of Page 752 dragline ......................................................................55 

D–2. Leq(A) sound levels in house of Page 757 dragline ......................................................................56 

D–3. Leq(A) sound levels in house of Bucyrus-Erie 1260W dragline...................................................56 

D–4. Leq(A) sound levels in house of Bucyrus-Erie 1310W dragline...................................................57 

D–5. Leq(A) sound levels in house of Bucyrus-Erie 2570W dragline...................................................57 

D–6. Leq(A) sound levels in house of Marion 195M dragline ..............................................................58 

D–7. Leq(A) sound levels in house of Marion 7800 dragline ................................................................58 

D–8. Leq(A) sound levels in house of Marion 8200 dragline ................................................................59 

D–9. Leq(A) sound levels in house of Marion 8750 dragline, 132-yd3 bucket......................................59 

 D–10. Leq(A) sound levels in house of Marion 8750 dragline, 110-yd3

 bucket......................................60 

D–11. Bucyrus-Erie 195B power shovel ................................................................................................60 

D–12. Leq(A) sound levels in house of Bucyrus-Erie 195B power shovel..............................................61 

E–1. Cumulative dose plot for a froth cell operator.............................................................................62 

E–2. Cumulative dose plot for a third-floor operator...........................................................................63 

E–3. Cumulative dose plot for an utilityman .......................................................................................63 

E–4. Half-shift cumulative dose plot for a wet-plant attendant ...........................................................64 

E–5. Cumulative dose plot for a sump floor operator ..........................................................................64 

E–6. Cumulative dose plot for a control room operator.......................................................................65
 

E–7. Cumulative dose plot for a floor 4 plant mechanic......................................................................65

 F–1 Leq(A) sound levels on a floor with many (23) vibrating screens ................................................66 

F–2. Leq(A) sound levels on a floor with 10 vibrating screens.............................................................67 

F–3. Leq(A) sound levels on a floor with eight vibrating screens.........................................................68 

F–4. Leq(A) sound levels on a floor with only two vibrating screens...................................................69 

F–5. Leq(A) sound levels on bottom floor containing sumps and pumps .............................................70 

F–6. Leq(A) sound levels on bottom floor containing sumps, pumps, and belts...................................71 

F–7. Leq(A) sound levels on top floor containing raw coal feed belt ...................................................72 

F–8. Leq(A) sound levels on floor with mostly centrifuges ..................................................................73 

F–9. Leq(A) sound levels on floor with magnetic separators only........................................................74 

F–10. Leq(A) sound levels around froth flotation cells...........................................................................75 

F–11. Leq(A) sound levels on floor with primarily belts ........................................................................76 

F–12. Leq(A) sound levels on floor with various types of processing equipment ..................................77
 
TABLES 

Page 

1. Dosimeter settings............................................................................................................................ 6 

2. Summary of worker noise exposure ................................................................................................ 9 

3. Summary of equipment/area sound level profiles ...........................................................................10
 

4. Characteristics of underground coal mines surveyed ......................................................................11 

5. Worker noise exposures in underground coal mines .......................................................................12 

6. Characteristics of surface coal mines surveyed ...............................................................................16 

7. Worker noise exposures in draglines ...............................................................................................16 

8. Summary of dose measurements inside and outside of surface mining equipment ........................17 

9. Summary of sound level measurements in draglines.......................................................................19 

10. Characteristics of coal preparation plants surveyed.........................................................................25 

11. Worker noise exposures in coal preparation plants .........................................................................25 

UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 

dB decibel Hz hertz 

 

dBA decibel, A-weighted min minute 

 

in inch sec second 

 

ft foot tph ton per hour 

 

ft2 square foot yd3 cubic yard 

 

hr hour 

 
EQUIPMENT NOISE AND WORKER EXPOSURE 

IN THE COAL MINING INDUSTRY 

By Eric R. Bauer, Ph.D.,1 Daniel R. Babich,1 

1

Mining engineer, Pittsburgh Research Laboratory, National Institute for Occupational Safety and Health, Pittsburgh, PA. 

and Jeffrey R. Vipperman, Ph.D.2 

2

Associate professor, Department of Mechanical Engineering, University of Pittsburgh, Pittsburgh, PA. 

ABSTRACT 

Prolonged exposure to loud noise can cause permanent damage to the auditory nerve and/or its 

sensory components. Despite regulations and efforts by government and industry to reduce noise-induced 

hearing loss (NIHL), it is still a problem in the U.S. coal mining industry. The Mine Safety and Health 

Administration noise standard (30 CFR3

3

Code of Federal Regulations. See CFR in references. 

 62), which was enacted in September 2000, is aimed at reducing 

NIHL in the mining industry. To address NIHL in various aspects of coal mining and provide the 

necessary information to effectively implement control technologies, the National Institute for 

Occupational Safety and Health conducted a cross-sectional survey of noise sources and worker noise 

exposures. Noise surveys consisting of full-shift worker noise exposure (dose) determination, timemotion studies (task observations), and equipment and/or area noise profiling were completed in 8 

underground coal mines, 10 surface coal mines, and 8 coal preparation plants. The studies revealed that 

more than 40% of all workers monitored were subject to noise exposures above 90 dBA TWA8. 

A summary of these studies is presented, their application to administrative and engineering controls is 

discussed, and exposure reduction methods are reviewed. 
_____________ 


 

GLOSSARY 

The definitions in this glossary are for the common noise and hearing loss prevention terms used in this 

report. If a more thorough definition or explanation is needed, see: NIOSH [1998], Franks et al. [1996], 

30 CFR 62.101, or 64 Fed. Reg.4 

4

Federal Register. See Fed. Reg. in references. 

2

49548 [1999]. 

A-weighting.—The weighting curve that accounts for the way the ear perceives the “loudness” of 

sounds. A-weighting is most responsive to the middle frequencies (500–4,000 Hz). 

Criterion level.—The sound level that, if constantly applied for 8 hr, results in a dose of 100% of the 

permissible exposure level (PEL). 

Decibel (dB).—The unit used to express the quantity of sound. The decibel scale is logarithmic: 0 dB 

approximates the threshold of hearing; 85–95 dB, the threshold of discomfort; and 120–140 dB, the 

threshold of pain. 

Decibel, A-weighted (dBA).—The sound level using A-weighting. 

Dose.—The amount of actual exposure relative to the amount of allowable exposure. The noise dose is 

calculated according to the following formula: 

D = (C1/T1 + C2/T2 ... + Cn/Tn) × 100, 

where Cn = total time of exposure at a specified sound level, hr; 

and Tn = reference duration of exposure at that sound level, hr. 

Dosimeter.—An instrument that measures sound levels over a specified interval, calculates the 

exposure as a function of sound level and sound duration, and describes the results in terms of dose, timeweighted average, etc. 

Equivalent continuous sound level (Leq).—The average sound level for a measurement period based on 

a 3-dB exchange rate. 

Exchange rate.—The relationship between sound level and dose, sometimes referred to as the 

“doubling rate.” For instance, if the level of an exposure increases by 5 dB (as adopted by the Mine Safety 

and Health Administration (MSHA)), the dose doubles. 

Noise.—Undesired sound. 

Noise-induced hearing loss (NIHL).—A sensorineural hearing loss that is attributed to noise. 

Noise reduction rating.—A single-number rating that attempts to describe a hearing protector based on 

how much the overall noise level is reduced by the hearing protector. 

Permissible exposure level (PEL).—A time-weighted average exposure that must not be exceeded 

during an 8-hr work shift. The MSHA PEL is 90 dBA. 

Response.—The time constant of the measurements that accounts for the fluctuations in the sound 

levels, i.e., dBA slow or fast. 

Sound.—Oscillation in pressure of a medium (air) that evokes an auditory sensation. 

Sound-level meter (SLM).—An instrument that measures sound and provides a readout of the resulting 

measurement in decibels. 

Threshold level.—An exposure level that, when reached or exceeded, may be hazardous. For the 

MSHA PEL, the threshold level is 90 dB. 

Time-weighted average–8 hour (TWA8).—The averaging of different exposure levels during an 8-hr 

exposure period that is equivalent to an exposure resulting from a constant noise level. 
____________ 

 


 

 

INTRODUCTION 

Prolonged exposure to high sound levels generally can cause permanent damage to the auditory nerve 

and/or its sensory components. This damage is known as noise-induced hearing loss (NIHL). It is 

irreversible and makes it difficult for the individual to hear and understand speech. NIHL is the most 

common occupational disease in the United States today. About 30 million workers are exposed to 

excessive noise levels or toxicants that are potentially hazardous to their hearing [Franks et al. 1996]. The 

problem is particularly severe in all sectors of mining. A previous analysis of NIHL in 1,349 coal miners 

revealed an alarming prevalence of severe hearing loss among older miners, as shown in Figure 1 [NIOSH 

1976]. The median hearing threshold of retired miners was 20 dB greater than that of the general 

population. By age 60, more than 70% of miners had a hearing loss of more than 25 dB, and about 25% 

had a hearing loss of more than 40 dB. A 1996 analysis of NIHL in miners, also performed by NIOSH, 

showed an apparent worsening of NIHL, as shown in Figure 2. This analysis of a private company’s 

20,022 audiograms indicated that the number of miners with hearing impairments increased dramatically 

with age until age 50, at which time 90% of the miners had hearing impairment [Franks 1996, 1997]. In 

addition to these findings by government researchers, academics have reported that the “policies and 

practices for preventing occupational hearing loss among miners are inadequate...there are deficiencies in 

nearly every sector: surveillance of exposure or of outcome, analysis, and intervention” [Weeks 1995]. 

The Federal Coal Mine Health and Safety Act of 1969 established requirements for protecting coal 

miners from excessive noise. Subsequently, the Federal Mine Safety and Health Amendments Act of 1977 

broadened the scope to include all miners, regardless of mineral type.5 

5

A metal/nonmetal noise standard was in place prior to 1977. 

Since the passage of these acts, 

there has been some progress in controlling mining noise. In fact, data from more than 60,000 full-shift 

MSHA noise surveys show that the noise exposure of certain occupations has decreased since the 1970s 

[Seiler et al. 1994]. However, in these same surveys, the percentage of coal miners with noise exposures 

exceeding federal regulations, unadjusted for the wearing of hearing protection, was 26.5% and 21.6% for 

surface and underground mining, respectively [Seiler et al. 1994]. 

Despite the extensive work with engineering controls, improved education, and hearing conservation 

programs in the 1970s and 1980s, NIHL remains one of the most pervasive health hazards in the mining 

industry [61 Fed. Reg. 66347 (1996)]. In response, MSHA published revised noise health standards for 

mining [64 Fed. Reg. 49548 (1999)]. One of the changes is the adoption of a provision similar to the 

Occupational Safety and Health Administration’s (OSHA) Hearing Conservation Amendment 

[46 Fed. Reg. 42622 (1983)].6 

6

The OSHA hearing conservation requirement, or action level, is 85 dBA TWA. Action level is exceeded when TWA 

≥ 85 dBA, integrating all sounds from 80 to 130 dBA. Exceeding the action level requires program inclusion, hearing tests, and 

optional hearing protection for the affected worker. 

3

 MSHA concluded in a recent survey that if an OSHA-like hearing 

conservation program were adopted, hypothetically, 78% of the coal miners surveyed would be required to 

be in a hearing conservation program [Seiler and Giardino 1994]. Other requirements of the revised 

regulations are a permissible exposure level (PEL) of 90 dBA TWA8, no reduction in the noise exposure 

due to the use of personal hearing protection (which was the policy in coal mines based on the noise 

reduction rating of the specific hearing protection being worn), and the use of all feasible engineering and 

administrative controls to reduce a miner’s noise exposure to the PEL. 
0 

20 

40 

60 

80 

MINERS WITH HEARING IMPAIRMENT, percen

Hearing loss > 40 dB 

Hearing loss > 25 dB 

0 20 30 40 50 60

AGE OF MINERS 

Figure 1.—Hearing loss as a function of miners’ age (adapted from NIOSH [1976]). 


 


 


 


 


 


 


 


 


 


 


 


 

100
 

MINERS WITH HEARING

IMPAIRMENT, percent

90
 

80
 

70
 

60
 

50
 

40
 

30
 

20
 

10
 

0
 

Non-Exposed Males 

Metal/Nonmetal Miners 

Coal Miners 

18 22 26 30 34 38 42 46 50
 

AGE, yrs 

Figure 2.—Hearing impairment in coal miners, metal/nonmetal miners, and nonoccupationally exposed males (from 

NIOSH [1996, 1997]). 

4
 

 

A further complication of the NIHL problem in mining is that much of the existing noise and worker 

exposure information is outdated and has limited value for current research and engineering control 

decision-making. In many cases, the data are specific to machine type and were obtained simply for 

characterizing noise sources rather than exposure assessment. There is also a great range in sound levels 

for a given occupation. For example, sound levels for continuous miner operators have a modal value of 

90 dBA and a range that varies from 80 to 105 dBA. As determined by the new noise health standards, 

a sound level of 80 dBA translates into a daily noise dose of 0%, while a 105-dBA level represents a daily 

noise dose of 800%. Yet, at present, there is insufficient information to explain this extreme variation in 

exposure for this and other mining occupations, and an understanding of this variability is necessary to 

identify appropriate solutions. Specifically, sound level data are needed that provide a time exposure 

history for workers correlated to information on noise sources. This information will provide the basis for 

targeting and selecting engineering controls, in combination with administrative controls and personal 

protection equipment, to reduce noise exposures among the mining workforce. 

SCOPE OF RESEARCH 

5
 

This research effort was conducted over several years and included eight underground coal mines, 

10 surface coal mines and 8 coal preparation plants throughout the United States (Figure 3). In total, 

approximately 463 worker noise exposures (MSHA PELs), 75 worker task observations and 

231 equipment noise profiles were completed. Noise exposure measurements were taken for longwall and 

continuous miner section face workers in underground mines, dragline crews at surface mines, and in-plant 

workers at coal preparation plants. The equipment noise profiles include stationary and semimobile 

underground mining equipment, floors, control rooms, electrical rooms, maintenance shops, and lunch 

rooms in preparation plants; and the “house,” revolving frame, and operator’s compartment of draglines. 

In addition, the mobile equipment at surface mines was monitored for dose inside and outside of the cabs. 
Figure 3.—Locations of noise surveys. 

 


 

INSTRUMENTATION AND DATA COLLECTION 

The instrumentation consisted of two basic sound monitoring instruments: personal dosimeters and 

sound-level meters (SLMs). Worker noise exposure was monitored using Quest Q–400 noise dosimeters 

(Figure 4). The microphone was located at the middle of the shoulder, per MSHA recommendations. This 

dosimeter is MSHA 2G permissible (tested for intrinsic safety in methane-air mixtures) and has two channels 

for monitoring dose using different parameters, referred to as dosimeter 1 and dosimeter 2. Dosimeter 1 was 

set to monitor the MSHA PEL, while dosimeter 2 was set to monitor all noise exposure (referred to as the 

wide range). The dosimeter settings are listed in Table 1.

Table 1.—Dosimeter settings 

Dosimeter 

No. 

Parameters and settings 

Weighting Threshold Exchange Criterion Designation Response level, dB rate, dB level, dB 

Upper 

limit, dB 

1...................... A 90 5 90 Slow 140 MSHA PEL. 

2...................... A 40 3 85 Slow 140 Wide range. 

 The MSHA PEL dose was the measurement of 

interest because mine and plant operators wanted information on which workers were out of compliance with 

the noise standards. The wide range dose was collected simply because it may be needed in the future for 

6
 

 

additional research analyses. In most cases, workers wore the dosimeters for the full shift to ascertain the 

true full-shift noise exposure. The dose information in the associated tables throughout this report gives a 

clearer picture of the extent of worker exposures, shows which occupations experience the most 

overexposures (both above the PEL and citable levels), and serves as a starting point for mine operators to 

begin implementing exposure reduction activities. 

Task observations (time-motion studies) were conducted either as a paper exercise (Figure 5) or by using 

a personal data assistant (PDA) and appropriate mobile data acquisition software (Figure 6). Workers 

wearing a dosimeter were followed and observed the entire shift. All tasks and/or locations were noted and 

start and stop times recorded in hr:min:sec. Cumulative dose plots were generated from the dosimeter data, 

then annotated using the corresponding observational data. Of interest were the periods of high dose 

accumulation, as indicated by a steep slope (approaching 1.0) of the graph’s cumulative dose data line. Mine 

operators can use the cumulative dose plots and task observations to pinpoint the activities that contribute the 

most to a worker’s dose. Knowing these activities allows mine operators to implement exposure reduction 

techniques for maximum benefit. 

Finally, equipment noise profiles and area sound level measurements were recorded using a Quest Model 

2900 SLM (where permissibility was required) or in combination with a Brüel & Kjær 2260 Investigator 

(where permissibility was not an issue). The SLM and Investigator were mounted side by side on a tripod 

(Figure 7), with the microphone 5 ft from the mine floor (approximate ear height), angled at 70N from the 

source (per manufacturer recommendations), and facing the sound source. In the underground coal mines, 

measurements were made on a 3- to 6-ft grid or at a distance of about 3–6 ft from the equipment when a grid 

was not possible. In draglines and in coal preparation plants, the measurements were also taken on a 

3- to 6-ft grid around stationary equipment and in all open areas to delineate the area noise levels. The 

measurement recorded that was of most concern was the A-weighted linear equivalent continuous sound 

pressure level (Leq(A)). The Leq(A) in decibels is the average sound level for a measurement period based on 

a 3-dB exchange rate. The 3-dB exchange rate is the method most firmly supported by scientific evidence 

for assessing hearing impairment as a function of noise level and duration [NIOSH 1998]. Measurements 

collected using a 3-dB exchange rate will result in slightly higher measured sound levels than if the MSHA 

noise standard requirement of a 5-dB exchange rate were used. When just the Quest 2900 SLM was used, 

only the Leq(A) was recorded at each location. When only the 2260 Investigator was used, the Leq(A), 

C-weighted and noise spectrum (linear 1/3-octave band frequency) were recorded. In addition, when both 

the 2900 SLM and 2260 Investigator were used, a linear Leq was recorded using the 2900, while the Leq(A), 

a C-weighted and noise spectrum (linear 1/3-octave band frequency) were recorded with the 2260. Both 

meters were set on slow response with an averaging time (length of measurement) of 30 sec. The Leq(A) and 

corresponding measurement locations were used to generate the sound profile plots using the Surfer 8 

software program from Golden Software, Inc. The plots are basically contour plots of sound levels generated 

by the equipment. Mine operators can use the sound profile plots in a number of ways. Their foremost use is 

as a training tool to alert workers where high noise levels exist and should be avoided and where hearing 

protection devices (HPDs) should be worn. In addition, the sound profile plots indicate the noisiest 

equipment and where engineering noise controls should be implemented first. 

7
 
Microphone 

Dosimeter 

Figure 4.—Quest Q–400 dosimeter and microphone placement. 


 

Figure 5.—Paper method of task observation [Bauer and Babich 2004a]. 

8 

Figure 6.—Task observation using a PDA. 
Figure 7.—Mounted Quest 2900 SLM (left) and Brüel & Kjær 2260 Investigator (right). 


 

RESULTS 

The results are presented by the three main areas of study: underground coal mines, surface coal mines 

and coal preparation plants. The results presented include worker dose, task observations and cumulative 

dose plots, and sound profile plots of equipment and area noise levels. In each area of study, only a 

representative sample of worker exposure (cumulative dose plots) and equipment noise (sound profile 

plots) are presented. The majority of cumulative dose plots and equipment noise profiles are included in 

the appendices at the end of this report. Table 2 summarizes the worker noise exposure monitoring for all 

sites, while Table 3 summarizes the equipment/area sound level profiling for all sites. Comprehensive 

discussions of the results in Tables 2–3 are provided later in this report in the individual sections pertaining 

to each of the three study areas. 

9
 

Table 2.—Summary of worker noise exposure 

Mine type Total dose 

measurements 

Number (percent) 

of doses > 100%1 

Number (percent) 

of doses > 132%2 

Underground coal ........................... 355 152 (43%) 98 (28%) 

Surface coal.................................... 63 14 (22%) 10 (16%) 

Coal preparation plants................... 45 25 (56%) 15 (33%) 1

MSHA PEL. 

2

Citable (>132%) MSHA PEL. 
Table 3.—Summary of equipment/area sound level profiles 

Mine type and 

equipment/location 

No. of 

profiles 

Range of 

Leq sound levels, 

dBA 

Underground coal, longwall:

 Hydraulic pump car .................................................. 

 Stageloader .............................................................. 

 Panel belt ................................................................. 

 Shearer..................................................................... 

 Head drive ................................................................ 

 Tail drive................................................................... 

 Panline ..................................................................... 

 Dinner hole ............................................................... 

Underground coal, continuous mining:

 Auxiliary fan.............................................................. 

 Roof bolter................................................................ 

 Continuous miner ..................................................... 

 Miner/bolter .............................................................. 

 Diesel mantrip .......................................................... 

 Feeder/breaker......................................................... 

 Loading machine ...................................................... 

 Center bolter............................................................. 

 Diesel scoop............................................................. 

 Diesel ram car .......................................................... 

 Shuttle car ................................................................ 

 Rock duster .............................................................. 

 Section belt............................................................... 

 Water pump.............................................................. 

 Power center ............................................................ 

 Diesel bobcat............................................................ 

 Dinner hole ............................................................... 

Surface coal:

 Dragline house ......................................................... 

 Power shovel house ................................................. 

 Dragline operator's cab ............................................ 

 Power shovel operator's cab .................................... 

Coal preparation plants:

 Floors ........................................................................ 

 Electrical/master control center (MCC) rooms .......... 

 Static thickener (outside)........................................... 

 Control room.............................................................. 

 Lunch room ............................................................... 

5 

6 

4 

9 

2 

2 

6 

5 

5 

2 

6 

8 

2 

5 

1 

3 

1 

3 

12 

1 

3 

3 

5 

1 

3 

16 

1 

16 

1 

58 

9 

8 

8 

8 

 

72–102 

84–102 

83–100 

85–99 

86–96 

92–94 

81–92 

<60–90 

84–121 

86–112 

78–109 

85–106 

86–105 

81–101 

93–101 

81–97 

88–95 

86–94 

78–93 

93 

80–90 

80–90 

<85 

82–85 

<80 

88–112 

91–100 

64–79 

76 

83–115 

74–90 

73–83 

71–80 

64–79 

10 
 

Underground Coal 

Studies were conducted in eight underground coal mines in Alabama, Colorado, New Mexico, 

Pennsylvania and West Virginia. At five of the mines, both the longwall and continuous mining machine 

(CM) sections were investigated. At one of these sites (a multiple-seam situation), the longwall surveyed 

was operating in the upper seam and the CM units investigated were in the lower seam. At the seventh 

location, only the diesel ram cars on a continuous miner section were investigated. Finally, at the eighth 

mine, only the longwall section was investigated. At each mine site, only face workers wore dosimeters 

and primarily only face equipment was monitored. This is because face workers (those directly involved 

with the mining of the coal seam) are most likely to experience significant noise exposures and face 

equipment is most responsible for the exposures. Other outby workers may be subject to noise exposures, 

including belt cleaners and motormen, but these occupations were not monitored. At one site, several 

outby belt drives were monitored per the wishes of mine management. Table 4 lists the characteristics of 

each mine surveyed. Table 4 simply illustrates the diversity of the sites. Studies were completed in mines 

of varying size (production levels and number of employees), from a number of states and different coal 

seams. No particular conclusions concerning worker dose or equipment noise can be ascertained from this 

information. 
Table 4.—Characteristics of underground coal mines surveyed 

Mine 

No. State Coal seam(s) 

Production,

million tons

per year 

Average total

No. of

underground 

employees
 
 

1 and 2 ..... West Virginia ............. Lower Cedar Grove and Alma A ............. 5.8 276
 
 

3 ............... Colorado....................Wadge..................................................... 7.2 255
 
 

4 ............... West Virginia .............Pittsburgh................................................ 1.9 179
 
 

5 ............... Pennsylvania .............Pittsburgh................................................ 6.6 417
 
 

6 ............... Pennsylvania .............Pittsburgh................................................ 6.7 414
 
 

7 ............... Alabama .................... Blue Creek .............................................. 2.0 314
 
 

8............. New Mexico............ Fruitland No. 8................................. 7.7 271 

Source: MSHA [2000, 2001, 2002, 2004]. 


 

Worker Dose 

Table 5 lists the results of the worker noise exposure measurements on the longwall and CM sections 

and illustrates the wide range of recorded doses for each occupation. It lists the percent of recorded doses 

for each occupation that were above the MSHA PEL of 100% and the percent above the citable level of 

132%. It is noteworthy that all longwall occupations experienced doses above the MSHA PEL of 100%, 

which indicates an 8-hr TWA of at least 90 dBA. The longwall occupations of most concern for potential 

overexposures are those where more than 50% of the recorded doses were above 100%. These include 

both head and tail shearer operators, headgate operators, and relief shearer operators. All but two of the 

CM section worker occupations experienced doses above 100%; for four occupations, more than 50% of 

the doses were above 100%. These included the CM operators and helpers, roof bolter operators, 

miner/bolter operators, and miner/bolter roof bolter operators. Particular attention should be given not 

only to the occupations mentioned above, but also to any occupation where doses exceeded the MSHA 

PEL level of 100%, all of which have the potential to cause NIHL. Mine operators should use this 

information when addressing the occupations of highest exposure to apply exposure reduction activities. 

The percent of doses above the MSHA citable dose of 132% is important because if an MSHA 

inspector had made these measurements, a citation for exceeding the PEL (30 CFR 62.130) could have 

been issued. MSHA does not cite until the dose is above 132% because there is a 2-dB allowance (Type 2 

dosimeters have a ±2 dB error). From a violation standpoint, nearly all of the occupations listed in Table 5 

would have been subject to a citation at one time or another. Only the diesel ram car operators, loading 

machine operators, and center bolter operators did not experience a citable dose. 

Task Observations 

To identify the tasks associated with and the noise sources responsible for the worker’s measured dose 

(noise source/exposure relationship), workers expected to experience exposures above the MSHA PEL 

(a dose of 100% or an 8-hr TWA of 90 dBA) were task-observed during one of the shifts during which 

they wore a dosimeter. The task observations included the start and stop times of the tasks performed by 

the worker and his/her location with respect to the equipment and/or noise sources. The ultimate goal was 

to provide mine operators with sufficient information about worker exposures and the cause of those 

exposures so that effective engineering and administrative noise controls could be implemented. This 

information was provided in the form of cumulative dose plots annotated with the task observations. 

11
 

 

Table 5.—Worker noise exposures in underground coal mines 

Section and occupation Sample 

size 

Range of 

MSHA PEL 

dose, percent 

Percent above 

MSHA PEL dose 

of 100% 

Percent above 

MSHA citable 

dose of 132% 

Longwall: 

 Tail shearer operator................................................. 

 Headgate operator .................................................... 

 Head shearer operator .............................................. 

 Relief operator........................................................... 

 Foreman.................................................................... 

 Jacksetter/shieldman................................................. 

 Mechanic/electrician.................................................. 

Continuous mining:

 Continuous mining machine operator/helper............. 

 Roof bolter................................................................. 

 Miner/bolter operator ................................................. 

 M/B roof bolter operator ............................................ 

 Utilityman/faceman.................................................... 

 Foreman.................................................................... 

 Diesel ram car ........................................................... 

 Shuttle car operator................................................... 

 Mechanic/electrician.................................................. 

 Loading machine operator......................................... 

 Center bolter operator ............................................... 

19 

18 

20 

2 

16 

43 

24 

 

14 

16 

14 

30 

37 

16 

4 

31 

18 

12 

17 

22–786 

36–386 

33–266 

22–193 

23–203 

13–192 

5–156 

44–347 

57–355 

45–195 

9–275 

6–297 

17–232 

83–122 

9–165 

4–162 

25–81 

17–57 

84 

73 

65 

50 

38 

37 

30 

86 

81 

64 

60 

32 

31 

25 

16 

6 

0 

0 

68 

56 

55 

50 

13 

19 

4 

57 

69 

21 

40 

22 

19 

0 

7 

6 

0 

0 

 

An example of a cumulative dose plot with task observations included is shown in Figure 8 (additional 

examples are found in Appendix A). The plot is for a roof bolting machine operator that bolted the mine 

roof using two different bolting machines and had a shift dose of 230%. As indicated by the sections 

where the slope of the line is nearly vertical, the worker received significant noise exposure (dose) while 

operating the spare roof bolting machine (about 130%, or nearly 60% of the total shift dose in 

approximately 2 hr). In addition, the worker received 25% dose while riding the mantrip (diesel pickup 

truck) into the section at the start of the shift (between 8:00 and 8:30 a.m.). The worker also accumulated 

dose while operating the main roof bolting machine, but at a significantly lower rate of accumulation, as 

indicated by the flatter slope of the line. Without the task observations, mine management would not have 

known the reasons for the operator’s dose, only that the operator’s dose was significantly greater than 

100%. The task observations allowed for pinpointing the major source or cause of the worker’s exposure, 

which was the operation of the spare bolting machine. The options for reducing this worker’s exposure 

include restricting time spent operating the spare bolting machine, using engineering controls to quiet the 

spare bolting machine, or replacing the bolter with a quieter one. 

Equipment Noise 

Approximately 110 equipment sound level profiles were completed in underground coal mines. Some 

of these profiles were done on similar equipment, but in different mines and working sections. The sound 

level data collected around mining equipment were converted to sound profile plots for visualization of the 

results. Space limitations prevent presentation of all of the sound level profiles for the studies conducted in 

underground coal mines; therefore, only representative examples are included in this section of the report. 

Additional examples from underground coal mines are included in Appendix B. 

12
 
250 

Bolting with main RBM 

200 

nt , perce

Tramming RBM 

CUMULATIVE DOSE 150 

100 Lunch 

High noise accumulation 

Percent 50 Bolting with spare RBM 

exposure 

PEL-90dB 

0 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00 

TIME OF SHIFT 

Duration of exposure 

Figure 8.—Cumulative dose plot for roof bolter operator, with task observations. 

Figure 9 is a sound profile plot for a longwall shearer as it cuts from head to tail. In this cutting 

direction, the tail drum cuts most of the coal and trims the roof, while the head drum simply cleans up 

along the mine floor. This figure illustrates that if the head drum shearer operator remains positioned 10 ft 

or more outby (toward the head and stageloader) the head drum, the sound levels are less than 90 dBA; 

thus, for an 8-hr shift and if the head shearer operator has no other exposure sources, the dose would be 

less than the MSHA PEL of 100%. On the other hand, the tail drum shearer operator needs to be 

positioned as far toward the head as possible, or at least at the middle of the shearer, to minimize noise 

exposure. Even at the midpoint of the shearer, the noise levels are between 90 and 95 dBA; thus, the 

operator is likely to be overexposed there or wherever he/she is positioned along the shearer. 

Figure 10 shows the sound levels recorded around a dual-boom roof bolting machine (Fletcher RRII– 

15–B) being operated on a continuous miner section. As expected, the highest sound levels were recorded 

near the operator’s locations during the bolting cycle, which included drilling the hole, inserting the bolt, 

and spinning the bolt to mix the resin. Sound levels are highest here because of drilling noise, drill 

steel/metal strap contact squeal, and machine hydraulics. Sound levels dropped below 90 dBA about 12 ft 

outby the drill. Note that the sound level above 110 dBA in the upper left corner of the plot was not 

actually recorded, but is a result of the existing data point interpolation process within the software 

contouring package. The implications for exposure reduction are that the drilling end of the machine 

should be addressed first when implementing engineering noise controls because the more significant 

exposure sources are found there. This would result in greater exposure reduction for the operators than if 

the drill exhaust muffler noise were addressed first. 

13
Figure 9.—Sound profile plot of sound levels for a longwall shearer. 

Figure 10.—Sound profile of sound levels around a dual-boom roof bolter. 

14
 

 

Finally, Figure 11 shows the noise levels measured around an auxiliary fan in a miner/bolter section. 

Figure 11.—Leq(A) sound levels around a Schroeder Model 271 auxiliary fan. 

This sound profile plot reveals that even in the main entry (listed as “No. 2 Entry” in Figure 11) where 

workers and equipment routinely travel, the sound level is still above 95 dBA. It is apparent that mine 

workers are subjected to unnecessary exposures when near the auxiliary fan; thus, standing, congregating, 

or working near the fan should be avoided. 

Surface Coal 

Studies were conducted in 10 surface coal mines in Arizona, New Mexico, North Dakota, Texas, 

Washington, and Wyoming. The mines used draglines for primary overburden removal and, in most cases, 

extracted several seams of varying thickness. The investigations at surface coal mines concentrated on the 

draglines, mostly because of company interest and the high exposure of dragline oilers; however, a power 

shovel, dozers and other surface mining equipment were investigated at some of the mines. Table 6 

summarizes the characteristics of the mines surveyed. 

15
 

 

Table 6.—Characteristics of surface coal mines surveyed 

Production, Average total Mine State million tons No. of No. 

per year employees 

1............Wyoming ...................... 0.6 80 

2............New Mexico.................. 8.0 362 

3............New Mexico.................. 2.2 236 

4............Arizona ......................... 4.6 247 

5............Arizona ......................... 8.5 408 

6............Texas............................ 4.0 176 

7............North Dakota ................ 7.6 235 

8............Washington .................. 5.8 548 

9......... Wyoming.................. 38.7 471 

10....... Wyoming.................. 29.7 302 

Source: MSHA [2000, 2001, 2002, 2004]. 

Worker Dose 

Table 7 lists the results of the worker noise exposure measurements recorded at the surface coal mines 

for dragline operators, oilers and dozer operators.

Table 7.—Worker noise exposures in draglines 

Occupation Sample

size 

Range of 

MSHA PEL dose, 

percent 

Percent above 

MSHA PEL dose 

of 100% 

Percent above

MSHA citable

dose of 132% 

Dragline oiler................................................... 11 46–318 82 64 

Oiler/dozer operator ........................................ 2 86–193 50 50 

Dozer operator (groundsman)......................... 12 4–130 17 0 

Dragline operator ............................................ 13 1–63 0 0 

Dragline operator/oiler/dozer operator1 

........... 3 12–20 0 0 1

Worked a half-shift in dragline and a half-shift in dozer. 

 The dragline operator, as the title implies, operates the 

dragline from within the operator’s cab. The dragline oiler is responsible for the cleaning and greasing of 

the dragline. Most of the oiler’s responsibilities are located within the “house” of the dragline. The house 

is where the motors (drag, hoist, and swing), motor-generator (MG) sets, ropes and hoist and drag drums 

are located. The oiler is also responsible for handling the dragline cable during walking. The dozer 

operator’s primary responsibility is to level the bench so that the dragline can be walked along as 

overburden removal progresses down the bench. At a few sites, some job rotation was practiced, resulting 

in combined occupations (oiler/dozer operator and dragline operator/oiler/dozer operator). Table 7 shows 

that the oiler is the worker most likely to be overexposed to noise. In fact, 82% of the doses recorded for 

the oiler were over the MSHA PEL of 100%, while 64% were over the MSHA citable level of 132%. In 

all cases, the dragline operator’s dose was less than the MSHA PEL because this worker stayed mainly in 

the cab. The dozer operators had generally less exposure, with only 17% of the recorded doses above 

100%. In addition, the combined occupation of oiler/dozer operator can experience doses above the 

MSHA PEL if more time is spent in the dragline than the dozer. In this case, exactly half of the doses were 

above 100%. 

Table 8 summarizes the dose measurements for other surface mining equipment and compares the 

inside-cab dose (dosimeter worn by operator) to the outside-cab dose. The outside dosimeters were usually 

taped to a handrail somewhere between the cab and engine compartment. The comparison shows that the 

equipment cabs are effectively isolating the operator from engine and operational noise, that the operators 

are operating the equipment for the most part with the windows and doors closed, and that the sound 

isolation properties of the cabs are continuing to be maintained. 

16
 
Table 8.—Summary of dose measurements inside and outside 

of surface mining equipment 

Manufacturer and 

equipment type Model 

Operator/inside 

cab dose, 

percent 

Outside cab 

dose, percent 

Caterpillar:

 Dozer............................ 

 Dozer............................ 

 Dozer............................ 

 Dozer............................ 

 Dozer............................ 

 Dozer............................ 

 Dozer............................ 

 Dozer............................ 

 Dozer............................ 

 Motor grader ................. 

 Front-end loader........... 

 Water truck ................... 

Euclid:

 Ash truck....................... 

 Ash truck....................... 

Ingersoll-Rand:

 Overburden drill............ 

 Overburden drill............ 

Rimpull:

 Haul truck ..................... 

 Haul truck ..................... 

Volvo:

 Coal drill........................ 

 

D9N 

D10N 

D10N 

D10N 

D10R 

D11N 

D11R 

D11R 

D11R 

16G 

994 

ND 

 

R85B 

R90B 

 

DM–M2 

DM–M2 

 

ND 

ND 

 

SE3132 

25.35 

9.42 

9.57 

46.08 

1

4.40 

11.74 

10.84 

13.81 

24.57 

14.63 

16.48 

11.00 

2.22 

5.52 

3.99 

17.55 

0.62 

7.53 

11.83 

231.65 

164.11 

201.13 

121.15 

122.31 

297.70 

286.38 

347.10 

374.57 

19.97 

485.55 

209.88 

199.13 

302.69 

201.89 

190.28 

52.01 

69.83 

103.42 

ND Not determined. 1

Half-shift dose.
 


 

Task Observations 

The dragline oilers were the only workers task-observed for one of the shifts during which they wore a 

dosimeter. Examples of cumulative dose plots for a dragline oiler with task observations included are 

shown in Figures 12–13. Figure 12 is typical for a dragline oiler, from an exposure perspective, and 

illustrates that the oiler receives the most exposure while working in the house (denoted by steep line 

slope) and little, if any, exposure when in the cab (denoted by flat line slope) while the dragline is 

operating (digging, swinging, or dumping). Figure 13 illustrates that the oiler can accumulate significant 

dose even when the dragline is not operating (see center portion of graph between 10:00 and 11:00 a.m.) 

because the exhaust fans and MG sets are still operating and creating sufficient noise to cause measurable 

exposures. Combining the dose measurements and observations reveals the importance of limiting the 

oiler’s time in the house through the use of administrative controls. The likely scenario is to employ more 

job rotation between the dragline operator, oiler, and dozer operator during each work shift. 

17
 
CUMULATIVE DOSE, percent 

 

200 

In house, sweeping, using comp. air 

In cab 150 

In cab 

100 

Walking 

Cleaning mostly in rev. frame 

50 

In cab 

Safety checks in house PEL-90dB 

0 

7:00 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 

TIME OF SHIFT 

Figure 12.–Cumulative dose plot for a dragline oiler, Marion 8750 dragline [Bauer and Babich 2003, 2004b]. 

 

 

180 

No observations 

160 

In cab, lunch and operating dragline 

140 

CUMULATIVE DOSE, percent 

On cable tractor 120 

In house and revolving frame 

100 

In house mopping while motor blowers down and dragline not working Outside cleaning steps 

80 

60 

40 In cab In house and revolving frame 

20 Off dragline in cable tractor 

MSHA PEL, 90 dB In house In house and cab 0 

7:00 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 

TIME OF SHIFT 

Figure 13.—Cumulative dose plot for oiler when dragline is not operating. 

18
 

 

Dragline Noise 

At each surface mine, sound level measurements were taken in the house, revolving frame, and 

operator’s cab of the draglines. Depending on the size of the dragline and amount of open and accessible 

area in the dragline, from 13 to 175 data measurement locations were required to delineate the sound 

levels. Figure 14 is an example of typical measurement locations in a dragline house and cab. A total of 

123 measurement locations were necessary to record the sound levels in all open areas in the dragline, 

a Marion 8750. The major noise sources in a dragline house are the MG sets (Figure 15), hoist and drag 

motors (especially the motor-blower fans) (Figure 16), swing motors and gear housing (Figure 17), and 

exhaust fans. Table 9 summarizes the sound level measurements taken in the house of the 16 draglines 

investigated.

Table 9.—Summary of sound level measurements 

in draglines 

Manufacturer and 

dragline model 

Bucket, 

yd3 

Range of 

Leq sound levels, 

dBA 

Page: 

 736 ....................... 

 752 ....................... 

 757 ....................... 

Bucyrus-Erie:

 1260W .................. 

 1370W .................. 

 1570W .................. 

 1570W .................. 

 2570W .................. 

Marion:

 195M .................... 

 7800 ..................... 

 8050 ..................... 

 8200 ..................... 

 8750 ..................... 

 8750 ..................... 

 8750 ..................... 

 8750 ..................... 

21 

42 

71 

 

35 

66 

92 

92 

100 

 

17 

36 

73 

75 

90 

110 

110 

132 

93–104 

88–100 

92–104 

98–105 

98–107 

97–110 

101–112 

96–107 
 

97–109 

93–99 

93–105 

88–105 

91–100 

98–108 

98–108 

95–105 
 

 Sound levels ranged from 88 to 112 dBA in the house, while those in the operator’s cab of all 

draglines were less than 80 dBA. The sound levels in a Page 736 dragline (Figure 18) are shown in 

Figure 19. The highest sound levels were recorded near the MG sets (over 100 dBA). The sound levels in 

a Bucyrus-Erie 1570W dragline (Figure 20) are shown in Figure 21. As with the Page dragline, the highest 

sound levels (over 105 dBA) were found around the MG sets. The sound levels in a Marion 8050 two-rope 

dragline equipped with a 73-yd3

 bucket (Figure 22) are shown in Figure 23. Sound levels from 93 to 

105 dBA were present, again with the highest sound levels (105+ dBA) near the MG sets. In addition, this 

sound profile plot indicates a “hot spot” of higher noise levels near one of the drag motors. This illustrates 

the usefulness of generating sound profile plots to reveal noise “hot spots” that may indicate where 

maintenance is needed. Clearly, because the sound levels in these three draglines, as well as the other 13, 

are nearly always greater than 90 dBA, they would contribute to the dose of any worker who spends part of 

his/her shift in the house of the draglines. 

Attempting to reduce noise levels and worker exposures would only be effective if engineering controls 

were applied to the MG sets first since they are the major noise source. One control that was shown to be 

effective when applied to MG sets is to isolate the MG sets from the rest of the house using noise curtains 

consisting of 2-in-thick fiberglass sandwiched between an outer protective shell. 

19
 

 

Figure 14.—Example of sound level measurement locations (x15) in a dragline. 

20

Figure 15.—Motor-generator sets in back of dragline. 

 

Figure 16.—Example of hoist and/or drag motors. 

Figure 17.—Swing motor and gear. 

Figure 18.—Page 736 dragline. 

21 
Figure 19.—Sound profile plot for a Page 736 dragline. 


 

Figure 20.—Bucyrus-Erie 1570W dragline. 

22
Figure 21.—Sound profile plot for a Bucyrus-Erie 1570W dragline. 


 

Figure 22.—Marion 8050 dragline. 

23
Figure 23.—Sound profile plot for a Marion 8050 dragline. 

24
 

Coal Preparation Plants 

Studies were conducted in eight coal preparation plants in Illinois, Kentucky, Pennsylvania, Virginia 

and West Virginia. The plants processed various coal seams, including the Pittsburgh; Pocahontas; 

Powellton; No. 2 Gas; Illinois No. 5, No. 5A, and No. 6; and Kentucky No. 9 and No. 11. Raw feed 

capacity of the plants ranged from 300 to 2,000 tph. Reject (rock and waste) averaged from 21% to 52% 

during the studies. All plants were of similar construction—steel I-beams covered by either single-ply 

corrugated steel sheeting (Figure 24), single-ply corrugated steel sheeting covered with foil-faced 

polyethylene bubble insulation, or two-ply sheeting with insulation between the plies, and concrete or steel 

grating floors. The number of floors in each plant varied from 5 to 12. Table 10 summarizes the 

characteristics of each plant. Investigations at the preparation plants included worker dosimetry and task 

observations of plant employees, and sound level measurements on all plant floors, control rooms, and 

lunch rooms. 

Worker Dose 

Table 11 lists the results of the worker noise exposure measurements recorded at the coal preparation 

plants. The occupations surveyed included the control room operator, plant controls man, 

mechanic/electrician, utilityman, and beltman. The last three occupations (mechanic/electrician, 

utilityman, and beltman) worked both inside and outside of the plant. For the most part, the control room 

operator remained in the quiet control room. At one plant, however, the control room operator had 

 

responsibilities on the floor outside of the control room, resulting in a dose of almost 100%. The plant 

operator is a catch-all title for any number of job classifications that require the worker to spend a 

considerable portion of the shift in the plant conducting equipment and process checks, cleaning, and 

taking process/flow/mixture status measurements. The occupations included in the plant operator category 

were plant controls man, froth cell operator, stationary equipment operator, third floor operator, wet-plant 

attendant, sump floor operator, plant backup, and floor plant mechanic. The utilityman duties included 

assisting the plant operator and/or the mechanics/electricians and serving as fill-ins when plant operators 

and beltmen are absent from work. Table 11 illustrates that the workers of most concern are the plant 

operators and mechanics/electricians because their doses are routinely over the MSHA PEL of 100% (79% 

and 80%, respectively). These two occupations are the most likely to incur a violation of 30 CFR 62.130 

for noise exposures exceeding the PEL (citable level of 132%) since they exceed that level by 50% and 

60%, respectively. 

25
 

Table 10.—Characteristics of coal preparation plants surveyed 

Plant 

No. State Coal seam(s) Raw feed, tph 

Reject, 

percent 

No. of

floors 

Total 

floor area, 

ft2 

1 ....... Pennsylvania ........Pittsburgh ............................. 1,000 31 8 58,200
 
 

2 ....... West Virginia ........Powellton and No. 2 Gas...... 2,000 52 6 81,850
 
 

3 ....... Pennsylvania ........Pittsburgh ............................. 2,000 33 12 142,650
 
 

4 ....... Virginia..................Pocahontas .......................... 1,000 27 7 63,350
 
 

5 ....... Pennsylvania ........Pittsburgh ............................. 1,000 21 10 51,400
 

6 ....... Kentucky...............Kentucky No. 9..................... 300 38 5 15,505
 
 

7 ....... Kentucky...............Kentucky Nos. 9 and 11 ....... 2,000 51 5 75,084
 
 

8 ....... Illinois....................Nos. 5, 5A, and 6.................. 1,500 38 5 31,582
 

Table 11.—Worker noise exposures in coal preparation plants 

Occupation Sample 

size 

Range of 

MSHA PEL 

dose, 

percent 

Percent above 

MSHA PEL dose 

of 100% 

Percent above 

MSHA citable 

dose of 132% 

Mechanic/electrician.... 5 18–209 80 60 

Plant operator.............. 24 38–221 79 50 

Utilityman..................... 6 8–104 33 0 

Control room operator . 9 0–100 0 0 

Beltman ....................... 3 60– 72 0 0 
Figure 24.—Typical coal preparation plant construction [Bauer and Kohler 2000]. 

26 
 

Task Observations 

A number of workers in the plant operator category were task-observed while working throughout the 

various plants. Figure 25 is a cumulative dose plot for a stationary equipment operator who received a 

considerable amount of exposure while hosing, inspecting, and cleaning on floor 5. An example of a 

cumulative dose plot for a mechanic/electrician is shown in Figure 26. The plot reveals where and what 

the mechanic was doing when receiving noise exposures. For instance, the worker experienced 

approximately 78% dose in less than an hour while performing repairs near the raw coal crusher on floor 9 

and another 50% dose in about 15 min while greasing belt rollers on floors 11 and 12. Certainly, repairing 

equipment near the raw coal crusher and greasing belt rollers are tasks that should be performed when the 

plant is down in order to reduce the mechanic’s noise exposure. For both of these workers, the task 

observations revealed the locations and tasks where plant management should focus its noise exposure 

reduction efforts. 

Area Sound Levels 

At each coal preparation plant, sound level measurements were taken on all floors and in the control 

room and lunch room. The control rooms and lunch rooms were quiet, with Leq A-weighted sound levels 

nearly always below 80 dBA. The individual floors of the plants had measured Leq A-weighted sound 

levels ranging from below 80 to 115 dBA. An example of a low-sound-level floor (<95 dBA) is shown in 

Figure 27, a high-sound-level floor (>95 dBA) in Figure 28, and a variable-sound-level floor (85 to 105 

dBA) in Figure 29. These figures show that distinct areas of low and high sound levels exist. Plant 

management can use those sound profile plots to instruct workers to avoid noisy areas and/or when and 

where to use HPDs, to map out travel paths in lower noise level areas, and to determine which equipment 

could benefit from engineering noise controls. 
110 

Control room 

100

Hosing, Floor 5 

90 Steps and checks, Floors 12-6 

CUMULATIVE DOSE, percent 80 

Lunch room & outside 

70 

60 Hosing near screens, Floor 5 Floor 5 inspecting screens 

50 

Mostly Floors 1 & 2 

40 

30 

Lunch room 

20 

Control room, lunch room and outside at static thickener 

10 

Equipment checks, all floors PEL-90dB 

0 

9:00 10:00 11:00 12:00 1:00 2:00 3:00 

TIME OF SHIFT 

Figure 25.—Cumulative dose plot for stationary equipment operator. 

CUMULATIVE DOSE, percent 

200 

180 1st Floor near lockers 

160 

Greasing belt rollers, Floors 11 & 12 

140 

Outside, Floor 1 

120 

6th Floor 

100 

Control room 

80 9th Floor, raw coal crusher 

60 Control room 

40 Lunch room 

20 Refuse pile welding bin 

PEL-90dB 

0 

9:00 10:00 11:00 12:00 1:00 2:00 3:00 

TIME OF SHIFT 

Figure 26.—Cumulative dose plot for prep plant mechanic. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

27

 

Figure 27.—Example of a low-sound-level preparation plant floor. 

28

Figure 28.—Example of a high-sound-level preparation plant floor. 
Figure 29.—Example of a variable-sound-level preparation plant floor. 

29 
 

IMPLICATIONS FOR EXPOSURE REDUCTION 

The goal of this research effort was simply to conduct sound level surveys and measure worker 

exposures. However, based on those efforts, some general comments concerning possible engineering and 

administrative controls for exposure reduction can be presented. Administrative controls are defined as 

“changes in the work schedule or operations that reduce worker noise exposures” [NIOSH 1998]. They 

isolate the worker from the noise. Evaluation of the cumulative dose plots, task observations, and sound 

level contour plots reveals the tasks, equipment, or areas that significantly influence a worker’s dose. 

Identifying and avoiding these influences can minimize worker noise exposures. Examples of 
30
 

administrative controls include job rotation, restricting access to noisy areas, or providing quiet areas and 

remote monitoring. 

Engineering controls are defined as “any modification or replacement of equipment, or related physical 

change at the noise source or along the transmission path (with the exception of hearing protectors) that 

reduces the noise level at the employee’s ear” [NIOSH 1998]. They isolate the noise from the worker. 

The sound level contour plots can indicate which equipment is generating the highest sound levels (but not 

what specific component of the piece of equipment is responsible). This at least provides mine operators 

with a starting point for engineering controls based on reliable and accurate information. Examples of 

engineering controls include maintenance, acoustic isolation (by barriers or enclosures) or absorption, 

modification of machine mounting, or replacement of noisy equipment with quieter equipment (i.e., “buy 

quiet”). 

Some overlap and confusion exists between engineering and administrative noise controls. For 

instance, a quiet booth is an engineering noise control because the sound level reaching the worker is 

reduced by a physical barrier between worker and source. However, requiring the worker to spend time in 

the booth is an administrative noise control because it reduces the time of exposure to the sound level 

outside the booth. The bottom line is that if the control reduces the worker’s exposure, then what it is 

called is not that important. 

NIOSH’s hearing loss research efforts have revealed some important considerations concerning 

exposure reduction and the implementation of either engineering or administrative noise controls. First, 

trial-and-error does not work but a systematic approach does. Second, an attitude of “same old, same old” 

does not work, but “thinking outside the box” does. NIOSH’s suggested approach for successful exposure 

reduction includes using a systematic approach, employing innovative solutions, involving workers in the 

process, conducting noise awareness training, and using HPDs properly. 

A suggested systematic approach for implementing an effective exposure reduction using administrative 

controls should include: 

1. Full-shift dosimetry to delineate a worker’s true exposure (dose); 

2. Task observations to pinpoint where and what a worker does during a typical shift; 

3. Comparison of dose to tasks to understand the task/locations responsible for a worker’s exposure; 

4. Obtaining representative sound level measurements to better understand the noise sources 

responsible for a worker’s exposure; 

5. Selection and implementation of appropriate administrative noise control based on the above 

information; and 

6. Followup on the control’s success and modification as needed. 

Finally, any successful exposure reduction method depends on two issues. First, success of any 

exposure reduction is contingent upon the person working at lower sound levels. Second, any exposure 

reduction must not introduce additional health or safety hazards. 

SUMMARY 

Overexposure to noise among mine workers continues to be a problem for the mining industry. To 

reduce or eliminate NIHL, the situation must be addressed by all mining concerns, including government, 

academia, and the mining industry. This research effort found that the most critical locations for attention 

are the face areas of underground coal mines, where 43% of workers were shown to experience noise 

exposures above the PEL, and coal preparation plants, where over 53% of the monitored workers 
31 
 

experienced noise doses above the MSHA PEL. At surface mines, equipment cabs were shown to isolate 

the operator from high noise exposures, while the dragline oiler working in the house of the dragline is 

most susceptible to overexposure (82% of the measured exposures were over the MSHA PEL). 

The solutions to reducing mine worker noise exposure are many and difficult and will need to include a 

combination of engineering and administrative approaches. It is imperative that a systematic approach that 

employs innovative thinking be used to effectively implement noise controls. “Trial-and-error” and 

“same-old, same-old” approaches are destined for failure. The approaches should also include providing 

additional training and supervision to increase the worker’s awareness of high sound level areas and the 

benefits of moving out or away from those areas when possible. The cooperation of all parties (labor, 

management, regulatory, and research community) is necessary if NIHL among mine workers is to be 

reduced and/or eliminated. 

ACKNOWLEDGMENTS 

The authors recognize the assistance of Michael D. DiMartino, Thomas J. Ozanich, Gerald S. Morrow, 

Alexander D. Prokop, James P. Rider, and Ellsworth R. Spencer of the NIOSH Pittsburgh Research 

Laboratory, who participated in the data collection phase of this research. 

REFERENCES 

46 Fed. Reg. 42622 [1983]. Occupational Safety and Health Administration: occupational noise 

exposure; hearing conservation amendment; final rule. (Codified at 29 CFR 1910.95.) 

61 Fed. Reg. 66347 [1996]. Mine Safety and Health Administration: health standards for occupational 

noise exposure in coal, metal, and nonmetal mines; proposed rule. 

64 Fed. Reg. 49548 [1999]. Mine Safety and Health Administration: health standards for occupational 

noise exposure; final rule. (Codified at 30 CFR 56, 57, 62, 70, and 71.) 

Bauer ER, Babich DR [2003]. Worker exposure and equipment noise in large surface coal mines. 

SME preprint 03–051. Littleton, CO: Society for Mining, Metallurgy, and Exploration, Inc., pp. 1–6. 

Bauer ER, Babich DR [2004a]. Administrative controls for reducing worker noise exposures. SME 

preprint 04–09. Littleton, CO: Society for Mining, Metallurgy, and Exploration, Inc., pp. 1–9. 

Bauer ER, Babich DR [2004b]. Worker exposure and equipment noise in large surface coal mines. 

Min Eng 56(4):49–54. 

Bauer ER, Kohler JL [2000]. Cross-sectional survey of noise exposure in the mining industry. In: 

Bockosh GR, Karmis M, Langton J, McCarter MK, Rowe B, eds. Proceedings of the 31st Annual Institute 

of Mining Health, Safety and Research. Blacksburg, VA: Virginia Polytechnic Institute and State 

University, Department of Mining and Minerals Engineering, pp. 17–31. 

Bauer ER, Podobinski DJ, Reeves ER [2001]. Noise exposure in longwall mining and engineering 

controls research. In: Proceedings of Longwall USA International Exhibition & Conference 

(Pittsburgh, PA, June 13–15, 2001). Overland Park, KS: Intertec Publishing Corp., pp. 51–69. 

CFR. Code of federal regulations. Washington, DC: U.S. Government Printing Office, Office of the 

Federal Register. 

Franks JR [1996]. Analysis of audiograms for a large cohort of noise-exposed miners. Cincinnati, OH, 

U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and 

Prevention, National Institute for Occupational Safety and Health, Division of Biomedical and Behavioral 

Science. Unpublished. 
Franks JR [1997]. Prevalence of hearing loss for noise-exposed metal/nonmetal miners. Cincinnati, 

OH, U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control 

and Prevention, National Institute for Occupational Safety and Health, Division of Biomedical and 

Behavioral Science. Unpublished. 

Franks JR, Stephenson MR, Merry CJ, eds. [1996]. Preventing occupational hearing loss: a practical 

guide. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers 

for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS 

(NIOSH) Publication No. 96–110. 

MSHA [2000]. Quarterly employment and coal production: accidents/injuries/illnesses reported to 

MSHA under 30 CFR 50. Denver, CO: U.S. Department of Labor, Mine Safety and Health 

Administration, Office of Injury and Employment Information. 

MSHA [2001]. Quarterly employment and coal production: accidents/injuries/illnesses reported to 

MSHA under 30 CFR 50. Denver, CO: U.S. Department of Labor, Mine Safety and Health 

Administration, Office of Injury and Employment Information. 

MSHA [2002]. Quarterly employment and coal production: accidents/injuries/illnesses reported to 

MSHA under 30 CFR 50. Denver, CO: U.S. Department of Labor, Mine Safety and Health 

Administration, Office of Injury and Employment Information. 

MSHA [2004]. Quarterly employment and coal production: accidents/injuries/illnesses reported to 

MSHA under 30 CFR 50. Denver, CO: U.S. Department of Labor, Mine Safety and Health 

Administration, Office of Injury and Employment Information. 

NIOSH [1976]. Survey of hearing loss in the coal mining industry. Cincinnati, OH: U.S. Department 

of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute 

for Occupational Safety and Health, DHEW (NIOSH) Publication No. 76–172. 

NIOSH [1998]. Criteria for a recommended standard: occupational noise exposure, revised criteria 

1998. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for 

Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) 

Publication No. 98–126. 

Seiler JP, Giardino DA [1994]. The effect of threshold on noise dosimeter measurements and 

interpretation of their results. Pittsburgh, PA: U.S. Department of Labor, Mine Safety and Health 

Administration, Pittsburgh Safety and Health Technology Center, Physical and Toxic Agents Division, 

Informational Report (IR) 1224. 

Seiler JP, Valoski MP, Crivaro MA [1994]. Noise exposure in U.S. coal mines. Pittsburgh, PA: 

U.S. Department of Labor, Mine Safety and Health Administration, Pittsburgh Safety and Health 

Technology Center, Physical and Toxic Agents Division, Informational Report (IR) 1214. 

Weeks JL [1995]. Policies and practices for preventing occupational hearing loss among miners are 

inadequate. In: Franks JR, Casali JG, eds. Proceedings of the Hearing Conservation Conference III/XX 

(Cincinnati, OH, March 22–25, 1995). Denver, CO: National Hearing Conservation Association, 

pp. 16–19. 

32
 
APPENDIX A.—CUMULATIVE DOSE PLOTS: UNDERGROUND COAL 

Appendix A includes a number of cumulative dose plots with annotated task observations for face 

workers in underground coal mines. As stated earlier in this report, these plots can be used to identify the 

tasks most responsible for a worker’s noise exposure and where noise controls should be implemented. 

A brief explanation of each plot follows. 

 Figures A–1, A–2, and A–3 are for workers from the same miner/bolter machine and illustrate the 

difference in dose for the three workers, even though the general trend of exposure was similar. The rightside bolter operator, bolting on the auxiliary fan side, experienced a dose of 260% (Figure A–2), the leftside bolter operator (Figure A–3) 145%, and the miner/bolter operator (Figure A–1) 128%. 

 Figures A–4, A–5, and A–6, although from different continuous mining machine sections, illustrate the 

exposure sources (tasks) for a CM operator, shuttle car operator, and CM helper, respectively. 

 Figure A–7 is the cumulative dose plot for a center bolter operator on a miner/bolter section. The bulk 

of exposure resulted from installing center bolts and waiting near the auxiliary fan. 

 Figures A–8 and A–9 are for the head and tail shearer operators, respectively. They illustrate that the 

rate of exposure accumulation was similar for both directions of cutting and that the tail shearer operator 

had the higher dose, as expected. 

 Finally, Figure A–10 is the exposure for a stageloader operator and shows a uniform dose accumulation 

while positioned along the stageloader. 

33
 

8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00 0

20

40

60

80

100

120

TIME OF SHIFT

CUMULATIVE DOSE, percent

PEL-90dB

Lunch

Equipment idle

Mantrip in

No power

Cutting/bolting/hang tubing

Aux. fan off

8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00 0

20

40

60

80

100

120

140

TIME OF SHIFT

CUMULATIVE DOSE, percent

PEL-90dB

Lunch

Equipment idle

Mantrip in

No power

Cutting/bolting/hang tubing

Aux. fan off

8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00

0

20

40

60

80

100

120

140

TIME OF SHIFT

CUMULATIVE DOSE, percent

PEL-90dB

Lunch

Equipment idle

Mantrip in

No power

Cutting/bolting/hang tubing

Aux. fan off

Trimming corner, empty conveyor

160

Figure A–1.—Cumulative dose plot for a miner/bolter operator. 
CUMULATIVE DOSE, percent 

Trimming corner, conveyor empty 

250 

Equipment idle 

200 

Lunch 

150 

100 No power Aux. fan off 

Mantrip in Cutting/bolting/hang tubing 

50 

PEL-90dB 

0 

8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00 

TIME OF SHIFT 

Figure A–2.—Cumulative dose plot for right-side roof bolter operator. 

180 

Trimming corner, conveyor empty 

160

140 Equipment idle 

CUMULATIVE DOSE, percent 120 

Lunch 

100 

80 Power off

60 Aux. fan off

40 Cutting/bolting 

20

PEL-90dB

0 

8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00 

TIME OF SHIFT 

Figure A–3.—Cumulative dose plot for left-side roof bolter operator. 

34
CUMULATIVE DOSE, percent 

Mantrip out 300 

No observations from 12:00 

250 to end of shift 

200 Lunch 

150 

Belt down 

Tramming Operating shuttle car 

100 

Mining entry 

50 

Mining crosscuts PEL – 90 dB 

0 7:00 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 

TIME OF SHIFT 

Figure A–4.—Cumulative dose plot for continuous mining machine operator. 

140 

Mantrip out 

Loading rock 120 

CUMULATIVE DOSE, percent 100 3 SCs running – wait time 

80 Lunch 

60 Setting miner bits 

40 Moving to new face 

20 

0 

7:00 8:00 

Loading rock 

Mantrip in 

9:00 10:00 11:00 12:00 

TIME OF SHIFT 

1:00 

PEL – 90 dB 

2:00 3:00 4:00 

Figure A–5.—Cumulative dose plot for shuttle car operator. 

35
 
 


 


 


 


 


 


 

160
 

140
 

100 

120

CUMULATIVE DOSE, percent 

PEL-90dB 

Help repair cable near aux. fans 

Lunch break 

Operating CM 

3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 

80
 

60
 

40
 

20
 

0 

TIME OF SHIFT 

Figure A–6.—Cumulative dose plot for continuous mining machine helper. 


 


 


 


 


 


 


 


 

40 

8:00 9:00 10:00 11:00 12:00 1:00 2:00 

PEL-90dB Waiting near aux. fan 

Tasks other than center bolting 

Bolting and tramming Lunch 

Mantrip in 

In dinner hole 

Not 

observed 35
 

30
 

25
 

20
 

15
 

10
 

5
 

0
 

TIME OF SHIFT 

Figure A–7.—Cumulative dose plot for center bolter operator. 

CUMULATIVE DOSE, percent 

36
 
	 0 

20 

40 

60 

80 

100 

120 

140 

160 

180 

200 

CUMULATIVE DOSE, percent 

PEL-90dB 

Equipment idle 

Cutting to tail (A) 

Cutting to head (B) 

(A) 

(B) 

(A) 

(B) 

(A) 

(B) 

(A) 

8:00	 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00 

TIME OF SHIFT 

Figure A–8.—Cumulative dose plot for head shearer operator [Bauer et al. 2001]. 

 

8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00

0 

50 

100 

150 

200 

250 

CUMULATIVE DOSE, percent 

PEL-90dB 

Equipment idle 

Cutting to tail (A) 

Cutting to head (B) 

(A) 

(B) 

(B) 

(A) 

(B) 

(A) Lunch 

TIME OF SHIFT 

Figure A–9.—Cumulative dose plot for tail shearer operator. 

37 
CUMULATIVE DOSE, percent 

200 

150 

100 

50 

0 

TIME OF SHIFT 

PEL-90dB 

Mantrip in 

Along belt 

At controls 

Along stageloader, various locations 

Stageloader off 

7:00 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 

Figure A–10.—Cumulative dose plot for stageloader (headgate) operator. 

38
 

 

APPENDIX B.—EQUIPMENT NOISE PROFILES: UNDERGROUND COAL 

This appendix contains sound profile plots for underground coal mining equipment. Figures B–1 and 

B–2 are for a Joy miner/bolter, while Figures B–3 and B–4 are for an Alpine miner/bolter. For the Joy 

miner/bolter, the sound levels were slightly higher during mining, while for the Alpine miner/bolter the 

levels were higher during bolting. 

Figure B–5 illustrates that the sound levels around a loading machine range from 90 to 100 dBA. These 

were recorded when the loading machine was near the miner/bolter and are higher than when the loading 

machine is back away from the miner/bolter. 

Figure B–6 is the sound profile plot for a single-boom center bolter. The exposure of the operator is 

governed by the high noise levels located near the operator’s position. 

Figures B–7 and B–8 show sound levels during coal conveyance for McLanahan and Stamler 

feeder-breakers, respectively. These plots reveal that the sound levels were slightly higher for the 

McLanahan feeder-breaker. 

Figure B–9 illustrates that the sound levels for two auxiliary fans approach 120 dBA, which is greater 

than the maximum MSHA allowable sound level of 115 dBA. 

The sound levels for a longwall shearer while cutting from tail to head are illustrated in Figure B–10. 

The sound levels are similar to those recorded when cutting the opposite direction (see Figure 9). 

Figures B–11 and B–12 are from a longwall section and show the sound levels for the stageloader and 

longwall hydraulics, respectively. Sound levels along the stageloader were approximately 85–95 dBA, 

with the highest sound level near the discharge. For the longwall hydraulics, the highest levels were 

recorded adjacent to the hydraulic pump cars. Although levels approached 105 dBA, worker exposure is 

usually limited to just a few minutes each shift as the workers walk to and from the mantrip and longwall 

face. 

39
 
Figure B–1.—Leq(A) sound levels around a Joy miner/bolter during mining. 

40
 
Figure B–2.—Leq(A) sound levels around a Joy miner/bolter during bolting cycle. 

41
 
Figure B–3.—Leq(A) sound levels around an Alpine miner/bolter during mining only. 

Figure B–4.—Leq(A) sound levels around an Alpine miner/bolter during mining and bolting. 

42
 
Figure B–5.—Leq(A) sound levels around a Joy Model 14BU10 loading machine. 

43 
Figure B–6.—Leq(A) sound levels around a Fletcher Model DR–15–E single-boom roof bolting machine. 

44 
Figure B–7.—Leq(A) sound levels around a McLanahan HV–50 feeder-breaker. 

Figure B–8.—Leq(A) sound levels around a Stamler Model BF–14A–1Z–530 feeder-breaker. 

45
 
Figure B–9.—Leq(A) sound levels around Spendrup Dual 50 and Dual 60 hp fans. 

46
 
Figure B–10.—Leq(A) sound levels near shearer while cutting from tail to head. 

Figure B–11.—Leq(A) sound levels around a longwall stageloader. 

47
 
Figure B–12.—Leq(A) sound levels around longwall hydraulics. 

48
 

 

APPENDIX C.—CUMULATIVE DOSE PLOTS: SURFACE COAL 

Cumulative dose plots with annotated task observations for dragline operators from a number of 

different draglines are shown in Figures C–1 through C–5 and in C–7 through C–9. All of the plots reveal 

the same exposure patterns, i.e., the oiler was most exposed when working in the house and revolving 

frame, was least exposed when in the operator’s cab, and received only minor exposure when outside the 

dragline during walking and operating the cable tractor. 

Figure C–6 is the cumulative dose plot for an oiler/groundsman. It shows that the worker experienced 

approximately 10% more dose while performing the oiler duties than when acting as the groundsman. 

This exposure occurred even though the worker performed oiler duties for only one-third of the shift and 

groundsman duties for the remaining two-thirds of the shift. 

Finally, Figure C–10 illustrates the extreme rate of dose accumulation for a welder while air arcing. In 

this case, the welder experienced over 350% dose in just under 1 hr of air arcing. 

49
 

300 

250 

CUMULATIVE DOSE, percent 100 

150 

200 

PEL-90dB 

In revolving frame 

On roof cleaning near fans 

In cab 

Walking 

On roof cleaning near fans 

In house near swing motors 

8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 

50 

0 

TIME OF SHIFT 

Figure C–1.—Cumulative dose plot for Marion 8050 dragline oiler. 
0 

50 

100 

150 

200 

250 

CUMULATIVE DOSE, percent 

PEL-90dB Off Dragline (Union Bus.) 

Cleaning in House, Left Side 

In Cab, Lunch 

In House, Mostly Near Grease Sta. 

And Between Drums 

In Cab 

By Swing Motor #2 

In House Cleaning with Comp. Air 

9:00 10:00 11:00 12:00 1:00 2:00 3:00 

TIME OF SHIFT 

Figure C–2.—Cumulative dose plot for Bucyrus-Erie 1260W dragline oiler. 

 

 

220 

CUMULATIVE DOSE, percent 

200 

180 

160 

140 

120 

100 

80 

60 

40 

20 

0 

8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 

PEL-90dB 

In House Cleaning with Comp. Air 

NOTE: Dragline not running until 2:40, drag 

rope broken 

In cab 

In house, mostly left side 

In house, only fans and MG sets running 

Using air wrench 

Outside 

Lunch 

TIME OF SHIFT 

Figure C–3.—Cumulative dose plot for Bucyrus-Erie 2570W dragline oiler. 

50 
0 

20 

40 

60 

80 

100 

120 

140 

160 

CUMULATIVE DOSE, percent 

PEL-90dB Outside fixing rope 

In cab 

In house 

In house, mostly front and left side 

In revolving frame 

In cab 

Mostly in house 

Mostly outside during walking 

Operating dragline 

9:00 10:00 11:00 12:00 1:00 2:00 3:00 

TIME OF SHIFT 

Figure C–4.—Cumulative dose plot for Marion 8200 dragline oiler. 

 


 


 


 


 


 


 


 


 


 


 


 

110
 

100
 

CUMULATIVE DOSE, percent 

90
 

80
 

70
 

60
 

50
 

40
 

30
 

20
 

10
 

0 

PEL-90dB In cab 

Outside during walk Cleaning with comp. air 

Checking and greasing in house 

Outside on cab side platform 

8:30 9:00 9:30 10:00 10:30 11:00 

TIME OF SHIFT 

Figure C–5.—Cumulative dose plot for Marion 7800 dragline oiler. 

51
 
 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

CUMULATIVE DOSE, percent 

In house MSHA PEL, 90 dBA 

In house near drag gear and walk motor 

In grease room and house 

At right walk mech. 

In cab 

In house (all over) 

In cab doing paperwork 

Outside handling cable 

Operating dozer 

On cable tractor, dozer, and water truck 

Operating dozer, door open 

In cab 

No observations 

In cab 

0 7:00 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 

TIME OF SHIFT 

Figure C–6.—Cumulative dose plot for Page 736 dragline oiler/groundsman. 

 

 

200 

180 

160 

140 

120 

100 

80 

60 

40 

20 

0 

0 60 120 180 240 300 360 420 480 540 600 660 720 780 

ELAPSED TIME, min 

MSHA PEL, 90 dB 

In house, no particular location 

Near diesel gen. for water pump 

Outside and on cable tractor 

In cab 

In house near swing motors Outside 

In house and tub 

In cab 

Outside and on cable tractor 

In house 

Outside during walk and in cab 

In house and tub 

On cable tractor during walk 

In cab 

Figure C–7.—Cumulative dose plot for Bucyrus-Erie 1570W dragline oiler. 

CUMULATIVE DOSE, percent 

52 
 

 

 


 


 

	 

180 

CUMULATIVE DOSE, percent 

No observations 

160 

In cab, lunch and operating dragline 

140 

On cable tractor 

120 

In house and revolving frame 

100 

In house mopping while motor blowers down and dragline not working Outside cleaning steps 

80 

60 

40 In cab In house and revolving frame 

20 Off dragline in cable tractor 

MSHA PEL, 90 dB In house In house and cab 

0 

7:00	 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 

TIME OF SHIFT 

Figure C–8.—Cumulative dose plot for Marion 8750 dragline oiler. 

53
 

 

 

140 

120 

100 

80 

60 

40 

20 

0 

No observations 

In cab, operating dragline 

In cab 

Dragline dow n for repairs to MG set 

In house In house, mostly right side 

In cab 

In house, right side In cab 

In house, left side MSHA PEL, 90 

0 60 120 180 240 300 360 420 480 540 600 660 720 780 

ELAPSED TIME, min 

Figure C–9.—Cumulative dose plot for Bucyrus-Erie 1370W dragline oiler. 

CUMULATIVE DOSE, percent 
0 

50 

100 

150 

200 

250 

300 

350 

CUMULATIVE DOSE, percent 

PEL-90dB 

Changing rods, adjusting amps/air pressure 

Break 

Plasma cutting 

Air arcing 

8 20 32 44 56 68 80 92 104 116 

TIME, min 

Figure C–10.—Cumulative dose plot for welder performing air arcing. 

54
 

 

APPENDIX D.—EQUIPMENT NOISE PROFILES: SURFACE COAL 

This appendix contains sound profile plots for surface coal mining equipment. Figures D–1 through 

D–10 are sound profile plots for the various draglines surveyed. The plots illustrate that the highest noise 

levels are found near the MG sets and sometimes around the drag and hoist motors. They also show that 

the operator’s cabs are quiet. 

Figures D–11 and D–12 are a photograph and sound profile plot for a power shovel, respectively. 

Figure D–12 illustrates that the inside of a power shovel can be quite noisy, with noise levels over 

100 dBA. 

55
 

Figure D–1.—Leq(A) sound levels in house of Page 752 dragline [Bauer and Babich 2003, 2004b]. 
Figure D–2.—Leq(A) sound levels in house of Page 757 dragline. 

Figure D–3.—Leq(A) sound levels in house of Bucyrus-Erie 1260W dragline [Bauer and Babich 2003, 2004b]. 

56
 
Figure D–4.—Leq(A) sound levels in house of Bucyrus-Erie 1310W dragline. 

Figure D–5.—Leq(A) sound levels in house of Bucyrus-Erie 2570W dragline. 

57
 
Figure D–6.—Leq(A) sound levels in house of Marion 195M dragline. 

Figure D–7.—Leq(A) sound levels in house of Marion 7800 dragline. 

58
 
Figure D–8.—Leq(A) sound levels in house of Marion 8200 dragline. 

Figure D–9.—Leq(A) sound levels in house of Marion 8750 dragline, 132-yd3

 bucket. 

59
 
Figure D–10.—Leq(A) sound levels in house of Marion 8750 dragline, 110-yd3

 bucket. 

Figure D–11.—Bucyrus-Erie 195B power shovel. 

60
 
Figure D–12.—Leq(A) sound levels in house of Bucyrus-Erie 195B power shovel. 

61
 

 

APPENDIX E.—CUMULATIVE DOSE PLOTS: COAL PREPARATION PLANTS 

Appendix E includes the cumulative dose plots with annotated task observations for workers in coal 

preparation plants. These plots can be used to identify the locations where the workers are exposed and 

where administrative noise controls should be implemented. A brief explanation of each plot follows. 

Figures E–1, E–2, E–3, E–5, and E–7 are for workers that spend a considerable portion of their shift in 

the plant, either on a single floor or many floors. These job classifications are listed mostly as the catch-all 

title of plant operator in Table 11. The result is that each of the workers received considerable exposure 

while in the plant, with PEL doses ranging from 105% to 220%. Their exposure was near zero when in the 

lunch rooms and control rooms, as indicated by the flat slope of the cumulative dose line. 

Figure E–4 is a half-shift plot for a wet plant operator and reveals that, as in the previous plots, the 

exposure was greatest while in the plant and near zero when in the control room. 

Finally, Figure E–6 is the plot for a control room operator. Although there are no observations, the near 

vertical slopes of the line indicate that either the worker left the control room numerous times during the 

shift or there is a frequent noise source within the control room. 

62
 

 

 

8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 0 

20 

40 

60 

80 

100 

120 

140 

160 

180 

200 

TIME OF SHIFT 

CUMULATIVE DOSE, percent 

PEL-90dB 

Lunch room 

Floor 2 hosing near dryers & centrifuges 

Control room 

Floor 2 hosing near slurry pumps 

Lunch room 

At static thickeners 

Floor 2 hosing near centrifuges 

Loading house coal 

Floor 2 hosing near bowl dryers 

Floor 1 hosing near CC conveyor 

Floor 2 hosing near slurry pumps 

Floor 2 hosing near centrifuges 

Lunch room 

At static thickeners 

Figure E–1.—Cumulative dose plot for a froth cell operator [Bauer and Babich 2004]. 
CUMULATIVE DOSE, percent 

150 

Checks floors 6, 5, 4, & 3 

Floor 3 

Lunch room 

100 

Mostly floor 3, hosing near screens Control room 

Floors 4 & 5 

Floor 3 hosing near screens Control room 

50 

Mezzanine floor 3 

Lunch room 

Plant down 

Control room PEL-90dB 

0 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 

TIME 

Figure E–2.—Cumulative dose plot for a third-floor operator. 

110 

100 Hosing along SBC belt, Floor 2 

90 

CUMULATIVE DOSE, percent 

Unclogging drain below SBC belt, Floors 1 & 2 

80 

70 

60 

50 Lunch room 

40 

Unclogging drain below SBC belt, Floors 1 & 2 

30 

20 

10 Hosing along belts, Floor 2 

PEL-90dB 

0 

9:00 10:00 11:00 12:00 1:00 2:00 3:00 

TIME OF SHIFT 

Figure E–3.—Cumulative dose plot for a utilityman. 

63
 

 

 

CUMULATIVE DOSE, percent 

10 

20 

30 

40 

50 

60 

70 

80 

PEL-90dB 

Control Room 

Outside at static thickener 

Checks, Floors 10 to 2 

Checks, Floors 10 to 2 

Outside at static thickener 

Control Room 

Working along main plant feed belt and drive, not running 

0 7:30 8:00 8:30 9:00 9:30 10:00 10:30 11:00 11:30 

TIME OF SHIFT 

Figure E–4.—Half-shift cumulative dose plot for a wet-plant attendant. 

64
 

 

 

 

 

 

0 

50 

100 

150 

200 

250 

6:00 7:00 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00 6:00 

TIME OF SHIFT 

CUMULATIVE DOSE, percent 

MSHA PEL, 90 dB 

Outside at static thickener 

Mostly Floor 2 

Floor 1 

Control room 

Floors 2, 3, and 4 

Out of plant, to office 

Floor 2 

Lunch, control room 

Floor 2, emptying decanter 

Floor 2, by decanter and TEMA dryer 

Floor 2, by decanter 

Floor 1 hosing 

Varies between outside and Floor 2 

Figure E–5.—Cumulative dose plot for a sump floor operator. 
	 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

CUMULATIVE DOSE, percent 

MSHA PEL, 90dB 

6:00	 7:00 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00 6:00 

TIME OF SHIFT 

Figure E–6.—Cumulative dose plot for a control room operator. 

 


 


 


 


 


 


 


 


 


 

160
 

140
 

120
 

100
 

80
 

60
 

40
 

20
 

0
 

8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 

TIME OF SHIFT 

MSHA PEL, 90 dB 

Control Room 

Control Room Control Room 

Control Room 

Lunch Room 

Floor 4 near screen repairs, B–2, #257 

Floor 4 near screen repairs, B–2, #257 

Floors 3, 31⁄2, and 4 

Floor 4, tightening bolts/belts on screens 

Using air chisel, floor 4 

Floor 4 

Operating forklift outside and floor 1 

Mostly floor 4 

Figure E–7.—Cumulative dose plot for a floor 4 plant mechanic. 

CUMULATIVE DOSE, percent 

65
 

 

APPENDIX F.—AREA NOISE PROFILES: COAL PREPARATION PLANTS 

This appendix contains representative sound profile plots, also referred to as area noise profiles, for 

floors in coal preparation plants. The plots simply show the sound levels (ranging from 85 dBA to over 

100 dBA) around typical coal processing equipment found in coal preparation plants. Mine operators can 

use these plots for noise awareness/avoidance training and to map out low-noise/reduced-exposure 

travelways throughout the plants. The plots also reveal equipment needing repair and where engineering 

noise controls are needed. These areas are indicated by localized high noise levels. For instance, Figure 

F–1 reveals a higher noise level at the second row of fine coal screens. This area should be investigated by 

mine management to determine the cause/source of the higher noise level, then dealt with appropriately. 

66
 

Figure F–1.—Leq(A) sound levels on a floor with many (23) vibrating screens. 
Figure F–2.—Leq(A) sound levels on a floor with 10 vibrating screens. 

67
 
Figure F–3.—Leq(A) sound levels on a floor with eight vibrating screens. 

68
 
Figure F–4.—Leq(A) sound levels on a floor with only two vibrating screens. 

69
 
Figure F–5.—Leq(A) sound levels on bottom floor containing sumps and pumps. 

70
 
Figure F–6.—Leq(A) sound levels on bottom floor containing sumps, pumps, and belts. 

71
 
Figure F–7.—Leq(A) sound levels on top floor containing raw coal feed belt. 

72
 
Figure F–8.—Leq(A) sound levels on floor with mostly centrifuges. 

73
 
Figure F–9.—Leq(A) sound levels on floor with magnetic separators only. 

74
 
Figure F–10.—Leq(A) sound levels around froth flotation cells. 

75
 
Figure F–11.—Leq(A) sound levels on floor with primarily belts. 

76
 
Figure F–12.—Leq(A) sound levels on floor with various types of processing equipment. 

77
 
Delivering on the Nation’s promise: 

Safety and health at work for all people 

through research and prevention 

To receive documents or more information about occupational safety and health topics, 

contact NIOSH at 

1 800 35 NIOSH (1 800 356 4674) – – – – – – 

Fax: 513 533 8573 – – 

E-mail: pubstaft@cdc.gov 

or visit the NIOSH Web site at www.cdc.gov/niosh 

DHHS (NIOSH) Publication No. 2007 10 –5 

SAFER ● HEALTHIER ● PEOPLE tm