ISSUE DATE: 06/18/08 

PROGRAM INFORMATION BULLETIN NO. P08-12 

FROM: KEVIN G. STRICKLIN

Administrator for 

Coal Mine Safety and Health 

FELIX A. QUINTANA

Administrator for 

Metal and Nonmetal Mine Safety and Health 

MARK E. SKILES 

Director of Technical Support 

SUBJECT: Technologically Achievable, Administratively Achievable, and 

Promising Noise Controls (30 C.F.R. Part 62) 

Scope

This Program Information Bulletin (PIB) applies to all Mine Safety and Health 

Administration (MSHA) enforcement personnel, equipment manufacturers, coal, metal, 

and nonmetal mine operators, independent contractors, miners, miners’ representatives, 

and other interested parties. 

Purpose

The purpose of this PIB is to provide guidance to operators, miners, miners’ 

representatives, contractors, and equipment manufacturers on technologically and 

administratively achievable engineering and administrative noise controls. This document 

also identifies those engineering and administrative noise controls which offer promise for 

further investigation. This PIB is a re-issuance of P04-18. The reason for this re-issuance is 

due to the recent NIOSH/MSHA upgrades of certain promising noise controls to 

technologically and/or administratively achievable noise controls. Specifically, this PIB 

addresses upgraded and additional controls for continuous mining machines, roof bolting 
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machines, and stone saws. 

Information

The performance-oriented noise standards in 30 C.F.R. Part 62 equate administrative and 

engineering controls and require that, when a miner’s noise exposure exceeds the 

permissible exposure level (PEL), all feasible engineering and administrative controls be 

utilized to reduce the miner’s exposure to the PEL. A feasible control is one that is both 

technologically (or administratively) and economically achievable. If such controls fail to 

reduce the miner’s exposure to the PEL, personal protection equipment must be provided 

and used. These standards do not permit the use of personal protection equipment in lieu 

of feasible engineering or administrative controls. A technologically or administratively 

achievable control or a combination of controls which achieves at least a 3 dBA reduction 

in a miner’s noise exposure is considered significant, even if it fails to reduce the miner’s 

exposure to the PEL. “If a miner’s noise exposure continues to exceed the PEL despite the 

use of all feasible engineering and administrative controls, the mine operator must 

continue to use the engineering and administrative controls to reduce the miner’s noise 

exposure to as low a level as is feasible.” (30 C.F.R. § 62.130(b)) 

This PIB describes technologically achievable and promising controls for several types of 

machinery used in mines. Many of the controls listed in Section One are in use throughout 

the mining industry and have been referenced by MSHA in prior noise control documents. 

This PIB also provides guidance on taking a practical approach to reducing miners’ 

exposure to noise. Section Two of this PIB is a checklist of simple, straightforward ways to 

control noise exposure. Examples of additional administrative controls are provided in 

Section Three of this PIB. MSHA’s Noise Enforcement Policy states that 

labor/management agreements will not be affected by the noise standard. MSHA will not 

require an operator to hire additional miners in order to “exhaust” all feasible 

administrative controls. 

For purposes of this PIB, MSHA limits use of the term “technologically achievable” to 

engineering controls. MSHA is mindful that this term is conventionally used to describe 

controls or devices that are mechanical in nature, rather than controls that reduce a miner’s 

noise exposure by actions such as adjusting work practices, rotating miners from noisy 

activities to quieter ones, rescheduling tasks, or modifying work activities. For this reason, 

this PIB refers to certain administrative controls as “administratively achievable,” rather 

than “technologically achievable.” As with those controls denoted as “technologically 

achievable,” use of the term “administratively achievable” to describe these administrative 

controls is solely intended to clarify that MSHA generally considers them to be capable of 

being done, executed, or effected, and not that it is necessarily economically achievable to 

do so. 
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Administratively and Technologically Achievable Noise Controls

Administratively and technologically achievable noise controls have demonstrated 

effectiveness either singly or as part of a suite of noise controls under actual mining 

conditions and are known to reduce sound levels and miner noise exposure in most cases. 

These controls: 

1. Reduce sound levels or exposure time, as demonstrated in widespread 

application on similar types of equipment operating as part of similar mining 

methods, or alternatively demonstrated as part of a scientifically designed 

study in which the results can be generalized; 

2. Reduce the noise exposure (3 dBA when used either singly or in combination) 

of miners performing the usual duties associated with the mining method 

and equipment, and based on measured miner doses; and 

3. An engineering control does not necessarily have to be prefabricated or offthe-shelf, but it must have a realistic basis in present technology. 

It is possible that unusual characteristics of the equipment, the mine, or the application 

could result in the inability of a technologically achievable control to reduce miner noise 

exposure, but it is unlikely. As with all technological achievability determinations, when 

these situations are encountered they will be evaluated on a case-specific basis. Some 

controls are technologically achievable, but only when used in more limited 

circumstances. These controls are considered conditional because they may work in some 

situations, and may not work in other settings; i.e., the case-by-case rationale. Some 

reasons for denoting a technologically achievable control as “conditional” would be: 

1. Its effectiveness is dependent on the conditions that exist at the mine site; or 

2. The installation and use of the control may create a collateral health or safety 

hazard which must be addressed. 

Case-by-Case Feasibility Determinations 

Recognizing that “one size does not fit all,” MSHA evaluates circumstances on a case-bycase basis to determine the achievability (technological or administrative and economic) of 

a listed control. Due to the large variety of mining equipment, mining methods and 

environmental conditions in mines, there may well be circumstances in which a described 

control is not technologically achievable for a specific application. 

Promising Controls

Technologically and administratively promising (promising) noise controls offer 

potential for noise reduction by having demonstrated effectiveness but may lack 

evaluation and/or documentation in terms of significant reduction of a miner’s noise 

exposure either singly or as part of a suite of noise controls. Technologically 
4

promising controls are being developed or studied by manufacturers, industry, and 

government. Some controls in this class demonstrate real potential and mine 

operators or equipment manufacturers may want to consider participating in 

cooperative research studies to further evaluate these controls. In general, promising 

controls: 

1. Have potential for reducing sound levels or exposure time based on 

laboratory or limited field studies; 

2. Have potential to reduce miner noise exposure based on time 

 studies of miners performing the usual duties associated with the 

 mining method and equipment; and 

3. May require further development, refinement, study or research. 

 MSHA and others will further evaluate their demonstrated effectiveness during in-mine 

production usage and MSHA will make updated information available. 

Other Considerations

While MSHA believes the listed controls are currently the most effective in reducing miner 

noise exposure, mine operators are not restricted in their selection of controls to those 

technologically and administratively achievable controls described in this document. 

They may use other administrative and engineering controls or combinations of controls to 

comply with MSHA’s noise standard. We encourage the mining industry to share 

information regarding controls that have been implemented and found to be successful in 

reducing a miner’s exposure to noise. Please contact MSHA’s Directorate of Technical 

Support to provide information about noise control advances in the mining industry. This 

PIB will be updated as additional technologies and controls become available.
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Section One 

Descriptions of Technologically Achievable, Administratively Achievable, and 

Promising Noise Controls 

Introduction

MSHA considers the engineering and administrative controls contained in this Program 

Information Bulletin (PIB) to be technologically or administratively achievable or to offer 

promise as noise controls which, when used either singly or in combination, have a 

demonstrated effectiveness or potential for achieving compliance with the PEL or for 

reducing a miner’s noise exposure by at least 3 dBA. MSHA and others are further 

evaluating the demonstrated effectiveness of promising controls during in-mine 

production usage and updated information will be made available. 

While the noise controls compiled in this PIB are on a machine/equipment basis, MSHA’s 

noise standards are occupational exposure standards, not equipment-based standards. 

Compliance with the noise standard is determined by the miner’s personal exposure and 

not the sound levels generated by the piece of equipment. Therefore, the miner’s total 

noise exposure should be examined from an occupational viewpoint and not solely on a 

machine or equipment basis. All sources/tasks that generate noise must be identified and 

considered when determining appropriate noise controls and their effects. Engineering 

and administrative noise controls should be applied to those occupational noise sources 

and tasks that will yield a significant reduction in the miner’s total noise exposure. For 

example, noise sources of 85 dBA or less should not require attention, especially when a 

competing noise source is at a much higher level. 

The implementation of retrofit noise controls involves the use of individual devices, 

systems and/or materials designed for the specific purpose of reducing noise. Acoustical 

devices include, but are not limited to, cabs, enclosures, barriers, mufflers, and silencers 

which decrease sound levels to which the miner is exposed, or other electro-mechanical or 

video systems which reduce the amount of time miners are exposed to excessive noise 

levels. 

Acoustical materials can reduce noise either by absorbing or blocking sound waves, or 

damping vibrations. These materials are generally referred to as absorption, barrier, 

damping, and composite materials, and they can substantially increase the effectiveness of 

other noise control devices. Selection of appropriate acoustical materials must be made 

based on firm noise control engineering principles and commensurate to the task, properly 

installed, used, and maintained. Also, mine operators should be aware of the flammability 

properties of acoustical materials and, prior to application, should consider MSHA’s 

flammability guidelines. These guidelines can be obtained by contacting MSHA’s 

Directorate of Technical Support, Approval and Certification Center. 
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In general, a noise control device specified by the original equipment manufacturer (OEM) 

and available for a specific piece of equipment will yield better results than one 

subsequently constructed by the mine operator, a third party or rebuild shop. 

However, much success in the mining industry in reducing sound levels has been realized 

through the design, production, installation, and use of noise controls developed by third 

party, after-market sources or individual mine operators. In the case of non-OEM noise 

controls, a detailed investigation and evaluation should be conducted on the machine or 

the environment to identify noise sources. This should be followed by the development of 

detailed instructions and specifications for the selection of appropriate acoustical materials 

and for the construction, fabrication, and installation of equipment-based noise controls. 

Engineering noise controls are effective when they are properly selected, installed, used, 

and maintained. Care should be taken in their selection such that they are appropriate to 

the equipment design, and do not have a harmful effect on the operation or performance 

of the machinery on which they are installed. Hazards caused by the application of 

engineering noise controls should be addressed to minimize the effects on a miner’s health 

and safety. 

For the purposes of this PIB, an “environmental cab” or “environmental booth” includes 

the structure plus the application and installation of appropriate acoustical materials to the 

inside areas of the cab or booth (e.g., absorption materials, composite materials or 

acoustical floor mat), and an appropriate air filtration/air conditioning system. A “skin 

kit” is a sectionalized cab (e.g., a 4-section metal cab without acoustical materials) that is 

attached to the roll-over protection system (ROPS)/falling object protection system (FOPS) 

on a piece of mobile surface equipment. Prior to implementing and attaching such a 

device, guidance from the ROPS and FOPS manufacturers should be obtained so as not to 

void any structural certification. 

This PIB contains a list of controls for the following equipment: 

1. Air Arcing 

2. Air-Actuated or Air-Operated Cylinders 

3. Augers - Surface 

4. Auxiliary Ventilation Fans 

5. Car Shakers and Rotary Dumps 

6. Channel Burners 

7. Continuous-Mining Machines / Augers / Loaders (Underground) 

8. Diesel - Locomotives 

9. Diesel - Underground Diesel-Powered Equipment 

10. Draglines, Shovels and Cranes Not Equipped with Operator Cabs 

11. Draglines, Shovels and Cranes Equipped with Operator Cabs 

12. Dredges and Associated Equipment 

13. Drills – Jumbo Drills 
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14. Drills – Truck Mounted/Blast Hole/Air Track 

15. Hand-Held Percussive Tools 

16. Longwalls 

17. Mantrips 

18. Mills / Processing Plants / Coal Preparation Plants (including Breakers at 

Anthracite Mines) 

19. Mobile Equipment - Surface 

20. Portable Crushers / Screening Plants and Associated Equipment 

21. Roof Bolting Machines 

22. Scalers 

23. Stone Saws 

1. Air Arcing

Air arcing is a major tool used in bucket maintenance on draglines and other similar 

equipment. A welder’s noise exposure depends on the amount of time spent using the air 

arcing equipment during the work shift. MSHA considers the following administrative 

noise controls, or a combination of these controls, to be administratively achievable in 

reducing the noise exposure of miners engaged in air arc welding: 

 Limit the duration of air arc welding per shift; 

 Rotate welding personnel from noisy activities to quieter ones; and 

 Avoid side-by-side air arc welding.

Other noise controls that offer promise when there would be a need for the use of air arcing 

include: 

• Reduction of air pressure to the minimum; 

• Use of constant current air arc welding/gouging techniques at the lowest effective 

current and air pressure; 

• Use of constant voltage air arc welding/gouging techniques at the lowest effective 

voltage and air pressure; and

• Use of alternate rods (certanium and cronatron gouging rods) or a plasma torch with a 

gouging tip (these methods may be appropriate only in specific applications).
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2. Air-Actuated or Air-Operated Cylinders

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable and effective in reducing the noise exposure of 

miners working around air-actuated or air-operated cylinders: 

 Mufflers on exhaust outlets/ports; 

 Hose extension on exhaust ports; and 

 Enclosures. 

MSHA considers the following engineering noise control to be conditional: 

• Barriers. 

3. Augers - Surface

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable in reducing the noise exposure of miners 

operating or working around surface augers: 

 Environmental cabs that include appropriately selected, correctly installed, 

and properly maintained acoustical materials (see 

 Section One Introduction) applied to internal surfaces; 

 Exhaust mufflers and redirection of exhaust; and 

 Low-cost barrier between the engine and the operator.

MSHA considers the following engineering noise control to be conditional: 

• Appropriately selected, correctly installed, and properly maintained 

acoustical materials (see Section One Introduction) in the operator’s 

compartment and the engine compartment. 
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4. Auxiliary Ventilation Fans

MSHA considers the following engineering and administrative noise controls, or a 

combination of these controls, to be technologically and administratively achievable in 

reducing the noise exposure of miners working around auxiliary ventilation fans: 

 Silencers matched to the fan; 

 Barriers or enclosures for work areas to minimize occupational exposures; 

 Locate fans away from areas where miners spend a significant amount of time;

and 

 Clean and maintain fan silencers on a regular basis. 

 

MSHA considers the following engineering noise control to be conditional: 

• Good maintenance practices, such as sealing air leaks and wrapping 

of ventilation tubing joints. 

The following controls offer promise in reducing the exposure of miners who may be in the 

vicinity of auxiliary ventilation fans: 

• Install flexible connections between the fan and ventilation tubing; 

• Install damping materials on tubing and fan blades; and 

• Line several tube sections with appropriately selected, correctly installed, and properly 

maintained acoustical materials at the inlet side of the fan on an exhausting face 

ventilation system.

5. Car Shakers and Rotary Dumps

Car shakers and rotary dumps are used to empty railroad cars containing coal or other 

materials. On a car shaker, electromagnets attach to the top of the car and vibrate the car 

so that the material falls out the bottom. A rotary dump grasps the car and rotates it, 

emptying it from the top. 

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable in reducing the noise exposure of miners 

working around car shakers or rotary dumps: 
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The following technologically achievable control is available for car shakers: 

The following technologically achievable controls are available for rotary dumps: 

The following controls may hold promise in reducing the noise exposure of car shaker 

operators: 

• Top pad attenuator; 

• Foot pads; and 

• Air-actuated cushions.

6. Channel Burners

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable in reducing the noise exposure of miners 

operating channel burners: 

 Operator environmental control booth that includes “appropriate acoustical 

 materials” (see Section One Introduction) applied to internal surfaces.

 Operator environmental control booth that includes “appropriate acoustical 

materials” (see Section One Introduction) applied to internal surfaces; and 

 Radio remote controls installed to position the operator away from the dump. 

 Automated channel burner to replace manual channel burners for 

 the majority of cuts. A handheld channel burner may be needed to initiate 

 the main cut or to perform specialty cuts; 

 Automated channel burner with a control booth and video monitoring 

 system to observe the cut; 

 Remote controls; and 

 Appropriate pressures for the fuel/air mixture as per manufacturer’s

 specifications. Use oxygen instead of air. 
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While MSHA considers the following noise controls to be technologically achievable in 

reducing the noise exposure of a miner operating a channel burner (or substitute 

equipment), the feasibility of their use must be evaluated on a case-by-case basis: 

 Slot drill in combination with a 3-sided or portable enclosure for the 

 operator; 

 Wire saw or diamond wire saw; 

 Use of hydraulic or pneumatic drill; and 

 Water jet cutter.

The following control offers promise in reducing a miner’s noise exposure: 

• Quiet tips on the burner. 

7. Continuous-Mining Machines / Augers / Loaders (Underground)

MSHA considers the following engineering and administrative noise controls, or a 

combination of these controls, to be technologically and administratively achievable in 

reducing the noise exposure of miners operating or working around this equipment: 

 Remote control with proper positioning of the operator; 

 Treated cutting heads on auger miners (e.g., the application of 

 stiffening gussets to the helix and filling of voids with sand); 

 Proper maintenance, such as replacing bent or misaligned conveyor flights 

or sides and use of a chain with proper tension or one having an automatic 

chain tension device; 

 Polyurethane coated conveyor flights; 

 Dual sprocket conveyor chain; 

 Locate the shuttle car change-out point away from major noise sources 

(e.g., auxiliary fan);

 Avoid idle parking in high noise areas;

 Keep miners away from auxiliary fans;

 Have mechanics and electricians avoid working near high-noise sources 

during maintenance;

 Reduce utility personnel working time near face and auxiliary fan;

 Limit operation of empty chain conveyors on all equipment (i.e., shuttle 

car, loading machine, continuous miner, miner-bolter, and feeder-breaker);

 Eliminate a high-pitched screech on continuous miners equipped with 

integral roof bolting machines by instructing roof bolters to drill straight 

holes and to avoid metal strap contact with the drill steel;

 Follow a cutting cycle (e.g., reduce cutting into roof and floor rock, cutting 

directly into in-seam rock, and over sumping) to minimize noise generation 

from both the continuous mining machine and the cutting process;
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 Regulate engine RPM on diesel-powered shuttle cars during loading and 

dumping; 

 Follow shuttle car loading and tramming procedures that minimize noise 

(e.g., time that the conveyor chain is turning, increase distance from 

continuous miner and its boom, etc.); 

 Follow loading and tramming procedures for loading machines that 

minimize noise; 

 Turn off any mobile equipment when not in operation; 

 Maintain proper fan blade clearance on dust scrubbers associated with 

continuous-mining machines; and 

 Constrained layer damping on the conveyor pan on an auger miner (e.g., 

the application of visco-elastic materials covered with wear steel to isolate 

the chain and flights from the conveyor pan line). 

The following engineering controls offer promise in reducing the noise exposure of miners 

working on continuous miner sections: 

• Transparent barrier between the operator and conveyor pan line; 

• Constrained layer damping on the conveyor pan on a continuous ripper miner (e.g., 

 the application of visco-elastic materials covered with wear steel to isolate the chain 

 and flights from the conveyor pan line); 

• Sand-filled conveyor decks; 

• Enclosure and isolation of motors and pump housings where they have been 

demonstrated to be a significant noise source; 

• Vibration isolation mounts on motors/pumps where they have been demonstrated to be 

 a significant noise source; 

• Isolated cutting bits (e.g., the application of vibration isolation materials between 

the bits/block and the drum); and 

• Sand-filled cutting heads. 

The following administrative control offers promise for reducing an operator’s noise 

exposure: 

• On continuous miners equipped with integral roof bolting machines, rotate center bolter 

operator with center bolter helper, roof bolter operators with utility personnel or shuttle 

car operators, miner-bolter operator with other machine operator, or continuous miner 

operator with shuttle car operator. 
13

The following noise controls offer promise for dust scrubbers associated with continuousmining machines: 

• Silenced fan housing; 

• Redesigned scrubber fan; 

• Sleeve-style attenuators; 

• Alternative face air flow distribution systems (e.g., spray fan systems); 

• Bolt-on attenuators; and 

• Appropriately selected, correctly installed, and properly maintained acoustical materials 

(see Section One Introduction) applied to the dust scrubber. 

8. Diesel - Locomotives

MSHA considers the following noise controls, or a combination of these controls, to be 

technologically achievable in reducing the noise exposure of miners working around this 

equipment: 

 Environmental cabs that include appropriately selected, correctly installed, 

and properly maintained acoustical materials (See 

 Section One Introduction) applied to internal surfaces; 

 Mufflers; 

 Video cameras with monitors to view the rail and loading process;

 Smooth rail joints; and

 Good machine and track maintenance.

MSHA considers the following engineering noise control to be conditional: 

• Appropriately selected, correctly installed, and properly maintained 

acoustical materials (see Section One Introduction) to the inside of 

the operator’s compartment.

The following engineering noise controls offer promise for reducing miners’ noise 

exposures: 

• Composite wheels to prevent wheel-track squeal; 

• Transmission enclosure; and 

• Application of sound damping materials to the floorboards at the transmission.
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9. Diesel - Underground Diesel-Powered Equipment

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable in reducing the noise exposure of miners 

operating underground diesel-powered equipment (e.g., LHD’s, shuttle cars, haul trucks, 

tractors, generators, graders, scoops): 

The following controls offer promise in reducing a miner’s noise exposure: 

• Redirection of the exhaust away from the operator; and 

• Remote controls.

10. Draglines, Shovels, and Cranes Not Equipped with Operator Cabs

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable in reducing the operator’s noise exposure: 

 OEM environmental cabs that include appropriately selected, correctly 

 installed, and properly maintained acoustical materials (see Section One 

 Introduction) applied to internal surfaces; and 

 Exhaust mufflers. 

 MSHA considers the following engineering noise controls to be conditional: 

• Non-OEM cabs; and 

• Appropriately selected, correctly installed, and properly maintained 

acoustical materials (see Section One Introduction) to reduce noise 

from the engine and transmission compartments. 

 Seal all openings (e.g., holes, cracks, openings around controls) to prevent 

outside noise from entering the operator compartment; and 

 Exhaust mufflers. 
15

The following administrative controls offer promise for reducing the mechanic/ 

greaser/oiler noise exposure: 

• Limit time spent in engine compartment when the machine is running; and 

• Perform cleanup duties when the dragline is not operating. 

11. Draglines, Shovels, and Cranes Equipped with Operator Environmental Cabs

MSHA considers the following engineering noise control to be technologically achievable

in reducing the operator’s noise exposure: 

MSHA considers the following engineering noise controls to be conditional: 

• A barrier behind the operator to block the noise path of the diesel engine 

from reaching the operator compartment. The barrier may be flexible, 

constructed of acoustical vinyl curtain, or rigid; 

• Appropriately selected, correctly installed, and properly maintained 

acoustical materials (see Section One Introduction) installed on the 

surfaces of the operator compartment, to the roof, sliding door, partition (if 

rigid) and any other available surface; and 

• Silencers on air discharge valves. 

 Existing OEM environmental cab including appropriately selected, 

correctly installed, and properly maintained acoustical materials

 (see Section One Introduction) applied to the interior surfaces. 

 MSHA considers the following engineering noise control to be conditional:

• Appropriately selected, correctly installed, and properly maintained 

acoustical materials (see Section One Introduction) to an existing OEM 

cab. 

Normally, the existing OEM environmental cab will be sufficient for assuring the 

operator’s compliance. 

MSHA considers the following engineering and administrative controls to be

technologically and administratively achievable in reducing the oiler’s noise exposure: 
16

 Performance of cleanup duties during downtimes for 

repairs/maintenance; 

 Limited exposure near the MG set; 

 Limited oiler time in the revolving frame; and 

 Rotation of the oiler and machine operator, oiler and dozer 

operator/groundsmen from noisy activities to quieter ones. 

The following engineering controls offer promise for reducing oiler and mechanic noise 

exposure: 

• Barrier installed in front of MG sets, or where practical, enclosing the MG sets 

 (may require additional ventilation or air conditioning); and 

• Silencers on cooling fan motors.

The following engineering and administrative controls offer promise for reducing the oiler 

noise exposure: 

• Silencers on compressed air discharge lines; 

• Reduction in the time spent in engine house and revolving frame by utilizing the 

following: 

o Automatic lubrication system; 

o Remotely monitored temperature sensors; 

o Remotely monitored oil level gauges; and 

o Remotely monitored video coverage of strategic areas. 

The oiler and mechanic, due to their work demands, must spend time in the environment 

of the engine house. The isolation of the MG sets by either constructing a partial barrier in 

front of the sets or by totally enclosing them would reduce the sound levels. The 

implementation of this promising control would most likely require additional ventilation 

or air-conditioning for the MG sets. 

12. Dredges and Associated Equipment

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable in reducing the noise exposure of the dredge 

operator: 
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The following engineering noise control offers promise for reducing miners’ noise 

exposures: 

• Video technology to position miners away from noise sources. 

13. Drills - Jumbo Drills

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable in reducing the noise exposure of miners 

operating jumbo drills: 

 Environmental cab/booth that includes appropriately selected, correctly 

installed, and properly maintained acoustical materials 

 (see Section One Introduction) applied to internal surfaces; 

 Pump enclosures; 

 Engine barriers; 

 Engine mufflers; 

 Resilient screen decking; 

 Barriers around pneumatic equipment; 

 Redirection of the exhaust; and 

 Enclosures / barriers at transfer points.

 Environmental cabs that include appropriately selected, correctly installed, 

and properly maintained acoustical materials (see Section One Introduction) 

applied to internal surfaces; 

 Barrier such as a windshield; and 

 Exhaust mufflers. 

 MSHA considers the following engineering noise controls to be conditional: 

• Barrier between the engine/compressor and the operator; 

• Flexible curtain material around the perimeter of the canopy; and

• Appropriate acoustical materials (see Section One Introduction) at the 

operator’s position on a cab equipped jumbo drill.
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While MSHA considers the following control to be technologically achievable in reducing 

the noise exposure of a miner operating a jumbo drill, the feasibility of its use must be 

evaluated on a case-by-case basis: 

The following controls offer promise in reducing miner noise exposures: 

• Remote controls; 

• Ceramic or other non-metallic centralizers on the drill assembly; 

• Programmable jumbo drills (computer automated); and 

• Wet drilling (i.e., injection of water under pressure into the air stream of the drill hole 

clearance system) where it can be implemented due to the jumbo drill’s design and when

 compatible with the geology and the mining method.

14. Drills – Truck Mounted / Blast Hole / Air Track

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable in reducing the noise exposure of miners 

operating drills: 

 Hydraulic drill.

 Environmental cabs that include appropriate acoustical materials (see 

Section One Introduction) applied to internal surfaces; 

 Exhaust mufflers and redirection of the exhaust away from the operator; 

 Portable enclosures / barriers for the operator; and 

 Appropriately selected, correctly installed, and properly maintained 

acoustical materials (see Section One Introduction) to treat the operator’s 

compartment. 

 MSHA considers the following engineering noise controls to be conditional:

• Barrier between the engine /compressor and the operator;

• Silencers on air release nozzles; and

• Relocation of the air compressor away from the air track drill.
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The following control offers promise in reducing miner noise exposures: 

• Wet drilling (i.e., injection of water under pressure into the air stream of the drill hole 

clearance system) where it can be implemented due to the drill’s design and is 

compatible with the geology and the mining method. 

15. Hand-Held Percussive Tools

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable in reducing the noise exposure of miners 

operating many types of percussive tools: 

16. Longwalls

MSHA considers the following noise controls, or a combination of these controls, to be 

technologically achievable in reducing the noise exposure of miners working around the 

longwall mining system: 

 Exhaust muffler; and 

 Body muffler.

 MSHA considers the following engineering noise control to be conditional:

• Piping exhaust away from the operator.

 Automated shear; 

 Automated jacks; 

 Automated stage loader; 

 Memory cut; 

 Proper maintenance such as use of proper chain tensioning and flight 

spacing; 

 Positioning of the miner to minimize exposure to noise such as keeping 

stageloader operator away from crusher, motors and gears, head drive, belt 

tail; head drum shear operator staying a minimum or 3 m (10 ft) outby the 

drum head; and 

 Reduced run-time for face and stageloader conveyors when empty. 

MSHA considers the following engineering noise control to be conditional:

• Remote operation. 
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MSHA also considers the following noise controls to offer promise in reducing the noise 

exposure of the shear operators and other miners working around the longwall mining 

system: 

• Barriers where appropriate; 

• Appropriately selected, correctly installed, and properly maintained acoustical materials 

(see Section One Introduction); 

• Rotation of head and tail shear operators with each other, shear operators with 

shieldman, stageloader operator with shieldman; 

• Video cameras to monitor the cutting and other functions to limit miner 

 exposure; 

• Enclosure of motors, gears, pumps where demonstrated to be a significant noise source 

and can be done without damage to the equipment; 

• Damping of enclosures and panels where demonstrated to be a significant noise 

 source; 

• Water-cooled motors instead of air-cooled motors where practical and when the motors 

are a significant source of noise exposure;

• Enclosure for the other miners (e.g., headgate operators) where practical; 

• Isolated cutting bits on the longwall drum (e.g., the application of vibration 

 isolation materials between the bits/block and the drum); and 

• Sand-filled cutting heads. 

17. Mantrips

Mantrips and other similar modes of transportation may be a significant contributor to a 

miner’s overall noise exposure and should be examined on a case-by-case basis. When 

attempting to reduce a miner’s noise exposure, there are instances where engineering 

controls should be applied to mantrips to achieve a significant reduction. 

MSHA considers the following noise controls, or a combination of these controls, to be 

technologically achievable in reducing the noise exposure of miners working around and 

riding in mantrips: 
21

 Muffler(s); 

 A fully enclosed passenger compartment

 Smooth rail joints; and

 Good machine and track maintenance.

MSHA considers the following engineering noise controls to be conditional: 

• Motor enclosure for those machines where the motor is a significant 

 noise source; and 

• A passenger compartment treated with appropriate acoustical materials

(see Section One Introduction).

The following control offers promise in reducing miner noise exposures: 

• Composite wheels to reduce wheel-rail squeal.

18. Mills / Processing Plants / Coal Preparation Plants

(Including Breakers at Anthracite Mines)

Miners working in mills, processing plants, coal preparation plants and breakers at 

anthracite mines, typically encounter high sound levels and are engaged in mobile 

occupations. Consequently, it is usually necessary to identify where and which tasks 

contribute the most to the miner’s overall noise exposure, i.e., time-motion study. The 

successful reduction of a miner’s noise exposure depends on the application of 

engineering and administrative controls to the locations and tasks which contribute the 

most to the miner’s overall noise exposure. Therefore, the application of these controls 

must be evaluated on a case-by-case basis. 

MSHA considers the following engineering and administrative noise controls, or a 

combination of these controls, to be technologically and administratively achievable in 

reducing the noise exposure of miners working in coal preparation plants and 

metal/nonmetal processing plants and mills: 
22

 Acoustically treated control booths; and 

 Full enclosures without a top around equipment or miner work locations; 

 Electro-mechanical sensing devices to limit exposure times; 

 Video technology to limit exposure time; 

 Bin-level indicators; 

 Rotation of plant operator with control room operator; inside mechanics 

with outside mechanics; high-noise floor workers with low-noise floor 

workers; and in-plant workers with outside-plant workers; 

 Limit plant worker time on noisy floors, working in or next to noisy 

equipment such as screens, crushers, centrifuges, and dryers; 

 Relocate work stations / controls to quieter locations; 

 Relocate tool boxes, cabinets, and supplies to quiet area; 

 Operate noisy equipment / processes (welding, grinding, etc.) when fewer 

miners will be exposed; and 

 Perform maintenance during downtimes, if possible. 

MSHA considers the following engineering noise controls to be conditional: 

• Partial enclosures without a top around equipment or miner work 

 locations; 

• Barriers, including curtains, especially on traveled walkways; 

• Acoustic baffles suspended above enclosures; 

• Resiliently backed mill liners; 

• Chute liners; 

• Covered chute enclosures; 

• Dead boxes and impact pads; and 

• Resilient screen decking. 

Other noise controls that offer promise for reducing the noise emitted from screens and 

other sizing devices include: 

• Replacement of spring mounts with vibration isolation mounts made of rubber, 

 ROSTA mounts, and air bags (due to the engineering parameters involved in this type 

of equipment and the forces generated being transferred to the structure, their use 

should be considered on a case-by-case basis in conjunction with the equipment 

manufacturer); 

• “Double isolation” mounting methods; and

• Banana screens (due to height requirements, banana screens may be applicable only in 

certain situations.)
23

The following administrative control offers promise for reducing an operator’s noise 

exposure in coal preparation plants: 

• Move density measuring to quiet location. 

19. Mobile Equipment -- Surface

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable in reducing the noise exposure of miners 

operating surface mobile equipment (e.g., bulldozers, front-end loaders, trucks, graders, 

scrapers): 

 Environmental cabs (primarily on equipment manufactured since the mid1970s) that include appropriately selected, correctly installed, and properly 

maintained acoustical materials (see Section One Introduction); 

 Exhaust mufflers; and 

 Redirection of the exhaust away from the operator. 

 MSHA considers the following engineering noise controls to be conditional:

• Installation of a full or partial skin kit to the ROPS/FOPS.

• Appropriate acoustical materials (see Section One Introduction) to

 treat the operator’s compartment.

The following control offers promise in reducing miner noise exposures: 

• Remote controls. 

20. Portable Crushers / Screening Plants and Associated Equipment 

MSHA considers the following noise controls, or a combination of these controls, to be 

technologically achievable in reducing the noise exposure of crusher operators: 
24

 Acoustically treated environmental control booths isolated from the 

 main structure through the use of vibration-isolation techniques or 

 through physical isolation (permanent or portable); 

 Remotely controlled picks; 

 Video monitoring of plant operations; 

 Mufflers; and 

 OEM controls on diesel engine/generator sets.

MSHA considers the following engineering noise controls to be conditional: 

• Sound damping material at transfer points; 

• Chute liners; 

• Resilient screen decking; and 

• Barriers, especially on traveled walkways. 

21. Roof Bolting Machines

MSHA considers the following engineering control and work practices to be 

technologically and administratively achievable in reducing a miner’s noise exposure 

when working on or around a roof bolting machine: 

 Wet drilling (where it can be implemented due to the roof bolter

 design and when compatible with the geology and mining method); 

 Sharp drill bits; 

 Starter drill steel to begin the hole; 

 Straight drill steel (one piece and with thick wall, if conditions and dust 

collection allow); 

 Replacement of worn or defective drilling components (e.g., drill pot 

bushings or bearings, worn steel, bent steel); and 

 Maintenance of manufacturer-recommended drilling parameters for 

thrust, torque, and rotational speed. 

The following engineering controls and work practices offer promise in reducing a miner’s 

noise exposure: 
25

• Automated dust collection system or actuation of the dust collection system motors only 

during drilling, or use of administrative controls to accomplish the same task; 

• Exhaust conditioner (water box) and/or manufacturer-recommended exhaust 

 muffler; 

• Chuck isolator; 

• Drill bit isolator; 

• Acoustic drill steel enclosure; 

• Controls for optimizing the drilling parameters (drill feedback system); 

• Water misting system (i.e., injection of a small volume of water in a mist form into the 

drill hole clearance system); 

• Grommet to isolate the drill steel and chuck; 

• Acoustical liner in the tool tray; and 

• Damped drill steels. 

22. Scalers

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable in reducing the noise exposure of miners 

working around scalers: 

 Environmental cabs that include appropriately selected, correctly installed, and 

properly maintained acoustical materials (see 

 Section One Introduction) applied to internal surfaces; 

 Sealing of openings (e.g., around the gear controls, doors); and 

 Muffler. 

MSHA considers the following engineering noise controls to be conditional:

• Appropriately selected, correctly installed, and properly maintained 

acoustical materials (see Section One Introduction) on the inside surfaces of 

existing cabs; and 

• Barrier between the engine and the operator. 

23. Stone Saws

MSHA considers the following engineering noise controls, or a combination of these 

controls, to be technologically achievable in reducing the noise exposure of the stone saw 

operator: 

 Operator booth with appropriately selected, correctly installed, and 

properly maintained acoustical materials (see Section One 

 Introduction) applied to internal surfaces; 

 Barrier between the saw and the operator; and

 Composite saw blades
26

There are two types of cutting blades. One is a silent core blade that is laminated. The 

other is a composite blade with filled expansion slots. These are available for all existing 

saws. Blade maintenance and the type of saw blade also are important factors. 

Methods that offer promise for reducing the noise exposure of miners using stone saws 

include: 

• Wet sawing systems. 
27

Section Two 

Practical Approach to Reducing A Miner’s Noise Exposure 

MSHA believes that there is a practical approach that can be taken to reduce a miner’s 

exposure to noise. Consideration of the responses to the following questions can be a 

valuable part of the noise control evaluation process. Besides the reduction of noise 

exposure, proper maintenance, work practices, and procedures, if applicable, may result in 

increased efficiency and less downtime. 

Maintenance 

• Are all existing noise controls maintained? 

OOO

• Are mechanical components / systems adequately maintained including maintaining and 

greasing rollers, bearings, hubs, etc.? 

• Are bolts tight, covers and compartments secure to prevent noise exposures? 

• Do smooth transitions exist between track rails? 

• Are openings around doors and between compartments sealed? Are air conditioners 

installed? Are broken windows repaired? 

• Is all equipment properly maintained to reduce excessive noise resulting from lack of oil, 

grease, worn parts, etc.? 

• Are miners instructed on proper use, operation and maintenance of equipment with noise 

controls? 

• Is the air conditioning in booths and enclosures maintained? 

• Are filters replaced on a scheduled basis for all air conditioners? 

Work Practices 

 • Are sharp cutting tools used? 

 • Do dust collection systems operate only when needed? 

• Are proper thrust, rotational speed, torque and chain tensioning being used? 

• Are good work practices being employed? 

• Are there work practices that result in unnecessary exposure to noise? 

• Are conveyors operated either wet or with materials? 

• Are doors and windows to cabs and booths kept closed? 
28

• Are radios turned off or the volume reduced as low as possible? 

• Is the exposed miner maintaining the greatest distance from the noise source while still 

being able to perform his/her job? 

• What kind of cleanup or maintenance is used, e.g., hand shovels vs. small loaders? 

• Do miners spend their breaks near high noise areas? 

• Do miners park or idle equipment in high noise areas for waiting, loading or dispatching? 

• Do miners stand next to high noise areas? 

• Are manufacturer’s air pressure recommendations followed for air-operated equipment? 

• Are manufacturer’s recommendations / maintenance schedules, etc. followed? 

• Are air hoses used for cleanup rather than manual tools, vacuuming, or washing down with 

water? 

• Is equipment located in such a manner to minimize miner exposures? 

Engineering / Administrative Controls 

• Are all feasible engineering and administrative controls installed and maintained?

• Are environmental cabs used on surface mobile equipment? 

• Can a video camera/monitor be used to observe critical operations, thus limiting a miner’s 

exposure? 

• Can a remote control system be used to remove an operator or miner from a noisy 

environment? 

• Are sound-treated booths provided for miner use, even on a periodic basis, where 

applicable? 

• Are exhausts directed away from miners? 

• Can miners be rotated from noisy activities to quieter ones to reduce exposure? 

• Has the proper type of acoustical material been selected to suit the job? Has consideration 

been given to the material’s flammability properties? 

• Do impact points employ vibration damping materials? 

• Do barriers separate miners and noise sources? 

• If multiple noise sources are present, can barriers be installed to prevent the combined 
29

effects of sources? 

• Is cleanup performed when the plant is running? 

• Are normal travelways located away from noise sources? 

• Are high noise areas identified with warning signs? 

• Are miners instructed to avoid these high noise areas? 

• Can noisy machines be replaced by quieter ones? 

• When new or used equipment is purchased, are noise controls included? Is sound level or 

exposure data included? 

• Is a “Buy Quiet” program in effect at the mine for the purchase of the quietest new and used 

equipment available? 

• Has noise been considered in operational design? 
30

Section Three 

Some Examples of Administrative Controls 

MSHA considers the following administrative controls to be applicable in many mining 

situations but administrative achievability must be assessed on a case-by-case basis. The 

following controls should be discussed with miners, miners’ representatives and mine 

operators during the inspection process, as appropriate. 

1. Adjust work schedules. 

• Share work tasks and/or rotate miners from noisy activities to quieter ones. 

• Schedule work tasks during quiet periods. 

• Limit duration of work shifts. 

2. Utilize work practices to lower noise exposures. 

• Position miners in quieter locations without increasing safety risks; 

• Keep miners from congregating at high-noise areas; 

• Provide quiet areas while taking breaks; 

• Limit the duration of noisy tasks; 

• Switch / rotate miners from high- to low-noise exposure jobs/occupations; 

• Modify work activities to shorten time or decrease noise level; 

• Provide job-task-analysis training for the specific occupation to complete tasks 

more efficiently, safely, and in a manner to reduce the occupational noise 

exposure; 

• Eliminate tasks that are unnecessarily noisy; 

• Operate noisy equipment or complete noisy tasks during periods when fewer 

miners will be exposed; and 

• Restrict or limit miner access to high noise areas. 

3. Use real-time noise dosimetry / instrumentation to measure exposures, trigger an 

administrative control, and prevent overexposures. 

4. Use remote sensing technology and video monitoring. 

5. Designate low-noise walkways /areas (e.g., dinner holes) or locate walkways 

/areas away from noise sources. 

6. Assure maintenance practices critical to reducing noise generation are identified 

and followed: 

• Keep chain tension adjusted to specifications; 

• Keep panels tightly bolted; 

• Keep seals around compartments secure; and 

• Keep drive trains aligned and lubricated. 
31

Background

Overexposure to occupational noise continues to be a pervasive health problem. In this 

light, MSHA intends to continue offering its assistance to mine operators in the 

implementation of the noise standard. 

Authority

The Federal Mine Safety and Health Act of 1977, as amended, 30 U.S.C. § 801 et seq.; 

30 C.F.R. Part 62 

Internet Availability

This information bulletin may be viewed on the Internet by accessing MSHA’s home page 

at http://www.msha.gov by choosing “Rules & Regs”, and “Compliance Assistance 

Information,” and “Program Information Bulletins.” 

Issuing Offices and Contact Persons

Technical Support 

John Seiler, Chief, Physical and Toxic Agents Division, Technical Support, 

412/386-6980 

Seiler.John@dol.gov

Technical Support 

John Faini, Chief, Approval and Certification Center, Technical Support, 

304/547-2029 

Faini.John@dol.gov

Metal/Nonmetal Mine Safety and Health 

William W. Wilson, M/NM, Chief, Division of Safety and Health, 

202/693-9643 

Wilson.William@dol.gov

Gene E. Autio, M/NM, Industrial Hygienist, Division of Safety and Health, 202/693-9635 

Autio.Gene@dol.gov

Coal Mine Safety and Health 

Robert A. Thaxton, Coal, Chief, Division of Health, 202/693-9515 

Thaxton.Robert@dol.gov 

John R. Hendley, Coal, Mine Safety and Health Specialist, Division of Health, 

202/693-9534 Hendley.John@dol.gov
32

Distribution

Coal, Metal/Nonmetal and All Volume Program Policy Manual Holders 

Surface Mine Operators 

Underground Mine Operators 

All Independent Contractors 

Special Interest Groups 

Equipment Manufacturers