ISSUE DATE: 06/20/2011

PROGRAM INFORMATION BULLETIN NO. P11-45

FROM: KEVIN G. STRICKLIN

 Administrator for

 Coal Mine Safety and Health

 NEAL H. MERRIFIELD

 Administrator for

 Metal and Nonmetal Mine Safety and Health

 LINDA F. ZEILER

 Acting Director of Technical Support

SUBJECT: Reissue of P08-12 - 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 P08-12. 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.
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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. Part 

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 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, 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.

Administratively and Technologically Achievable Noise Controls
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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 pre-fabricated or 

off-the-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 caseby-case 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 

promising controls are being developed or studied by manufacturers, industry, 
4

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 inmine 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. 

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
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13. Drills – Jumbo Drills 

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

15. Hand-Held Percussive Tools and Jackleg Drills

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;

 Avoid side-by-side air arc welding; and

 Use of constant voltage air arc gouging techniques at the lowest effective 

voltage and air pressure.

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 voltage air arc welding techniques at the lowest effective voltage and 

air pressure.

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

current 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).
8

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:

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

the vicinity of auxiliary ventilation fans:

• 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:

 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.
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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 engineering noise controls to be technologically 

achievable in reducing the noise exposure of a miner operating a channel burner, the 

feasibility of their use must be evaluated on a case-by-case basis:

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 on 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 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;

 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.
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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:

• Rotate center bolter operator with center bolter helper, roof bolter operators with 

utility personnel or shuttle car operators, miner-bolter operator with loading machine 

operator, or continuous miner operator with shuttle car operator.

 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).
13

The following noise controls offer promise for dust scrubbers associated with 

continuous-mining 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 engineering noise controls, or a combination of these 

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

working around this equipment:

The following engineering noise controls offer promise:

• Composite wheels to prevent wheel-track squeal;

• Transmission enclosure; and

• Application of sound damping materials to the floorboards at the transmission.

 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.
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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.
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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:

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:

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.
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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:

 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.
17

The following engineering noise control offers promise:

• 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.abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuv 

 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 and Jackleg 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 many types of percussive tools:

16. Longwalls

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 the longwall mining system:

 Exhaust muffler;

 Body muffler; and

 Remote control jackleg drills.

MSHA considers the following engineering noise control to be conditional:

• Piping exhaust away from the operator.
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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. 

 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 controls to be 

conditional:

• Remote operation.
21

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 engineering 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:
22

The following control offers promise in reducing miner noise exposures:

• Composite wheels to reduce wheel-rail squeal.

18. Mills / Ball 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:

 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).
23

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.)

 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; 

 Acoustical/Thermal Blankets; 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

 
24

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):

The following control offers promise in reducing miner noise exposures:

• Remote controls.

20. Portable Crushers / Screening Plants 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 crusher 

operators:

 Environmental cabs (primarily on equipment manufactured since the

mid-1970s) 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.
25

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:

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

miner’s noise exposure:

 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.

 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.
26

• 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:

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:

 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.

 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
27

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 in reducing the noise exposure of miners using stone saws 

include:

• Wet sawing systems. 
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O O O

 

O O O

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?

• 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? 
29

• 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 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?
30

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

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?
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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.

• 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.
32

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.”

Issuing Offices and Contact Persons

Technical Support

John Seiler, (412) 386-6980

E-mail: seiler.john@dol.gov

Technical Support

John Faini, (304) 547-2029

E-mail: faini.john@dol.gov

Metal Nonmetal Mine Safety and Health

Reginald J. Richards, DrPH, CIH, (202) 693-9600

E-mail: richards.reginald.j@dol.gov

Gene E. Autio, (202) 693-9600

E-mail: autio.gene@dol.gov

Coal Mine Safety and Health 

Robert A. Thaxton, (202) 693-9500

E-mail: thaxton.robert@dol.gov

John R. Hendley, (202) 693-9500

E-mail: hendley.john@dol.gov

Distribution

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

Surface Mine Operators

Underground Mine Operators

All Independent Contractors

O
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Special Interest Groups

Equipment Manufacturers