A Coal Mines Innovative Approach to Hearing Conservation: Lessons for the Military

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A Coal Mines Innovative Approach to Hearing
Conservation Lessons for the Military

• Alton Burks, Kevin Michael, and Rick Dillon

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Mining / Military Similarities

• Harsh conditions, hazardous environment
• Most workers overexposed
• Intermittent, variable exposures
• Communication requirements

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Mining / Military Similarities

• Traditional engineering and/or administrative
  control of noise difficult or impossible
• Monitoring of PPE difficult
• Workers are mobile

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Mining / Military Similarities

• Similar approaches traditionally taken toward
  hearing conservation
• Reliance on limited noise exposure data to assess
  long-term risk of NIHL
• Reliance on PPE to reduce exposures to safe levels

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Mining / Military Similarities

• Outcome of traditional approach
• Mining most miners have NIHL by age 50
• Military Millions in annual compensation for
  NIHL

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MSHA Performance-oriented Rule

• New MSHA rule disallows HPD rating-based
  correction of noise dose measurement
• Compliance to be achieved through administrative
  / engineering controls
• 90 dBA PEL, 85 dBA Action level, 5 dB exchange
  rate

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MSHA Performance-oriented Rule A Practical
Solution

• Solution based on innovative measurement
  technique
• Noise dose measurements made interior to the HPD
• Introduce the concept of continuous monitoring

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Inexpensive Noise Dosimetry
Conventional HPD
Continuous Monitoring
Dynamic Administrative Control Technology
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MSHA Performance-oriented Rule A Practical
Solution

• Design an inexpensive noise dosimeter that fits
  inside cup of an earmuff Exposure Smart
  Protector (ESP)
• Initiate Dynamic Administrative Control
  Technology (ACT-Now) every worker wears ESP
  every day

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Exposure Smart ProtectionTM (ESP)

• Innovation ESP measures actual exposure,
  whether worn by miner in primary (protected) or
  secondary (unprotected) positions

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ESP Primary Position
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ESP Secondary Position
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MSHA Performance-oriented Rule A Practical
Solution

• ESP provides pre-Action Level warning
• Rotate worker out of noise
• Require the ESP to be worn in primary position
  for remainder of shift
• ESP provides instantaneous gt 85 dBA warning

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MSHA Performance-oriented Rule A Practical
Solution

• Every miner wears ESP and downloads noise dose
  data every day via infrared establish complete
  noise exposure history
• Three levels of individual reinforcement 1)
  instantaneous gt 85 dBA indicator, 2) pre-Action
  Level indicator, 3) individual post-shift daily
  noise dose readout.

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MSHA Performance-oriented Rule A Practical
Solution

• Demonstrate concept through in-mine tests
• Validate equivalency of exposure measurements
  primary and secondary wearing positions

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ESP Readout Station
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Post-shift Data Download
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Results- Field Studies

• Steel Mill
• Metal/Non-Metal Mine
• Two Underground Coal Mines

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Steel Mill
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Industrial Sand Mine
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Above Ground Coal Study Air-Arcing Process

• Perhaps most difficult mining noise problem 110
  115 dBA process performed daily in above ground
  coal
• Field study results on-the-shoulder dosimeter
  135 noise dose in 1 hour, gt1000 dose 8 hour
  equivalent
• ESP measurement 0 dose under the muff

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Exposure Equivalency-ESP Measurement-

• Reference equivalent level in diffuse field with
  the worker absent center-of-head location
• Primary Exposure Smart Protector (ESP) position
  ear occluded by ESP
• Secondary ESP position ESP rotated back on
  hardhat
• Tests conducted on 10 subjects

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Error for ESP on Top of Hat, re. Center-of-Head

• Pink Noise 0.1 dBA
• Drill Noise 0.3 dBA
• Underground Noise 0.9 dBA
• Surface Noise 0.9 dBA

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ESP Error Due to TFOE, re. Center-of-Head

• Drill Noise 0.3 dBA
• Underground Noise 0.6 dBA
• Surface Noise 0.6 dBA

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ESP Dose MeasurementsSummary

• Noise exposure determined with the ESP represents
  the miners actual noise exposure, and not an
  estimate.
• Primary and secondary position dose measurements
  represent a conservative determination of a
  miners noise exposure.

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Innovative Approach to Hearing Conservation

• Current problems
• Unpredictable field performance of HPDs
• Non-representative lab attenuation measurements
  (and arbitrary de-ratings)
• Insufficient or inaccurate exposure measurements
• All of these problems go away.

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Innovative Approach to Hearing Conservation
Whats the NRR?
WHO CARES!

• The ultimate approach to training and motivation
• The ultimate approach to monitoring field
  effectiveness of HPDs
• Delineate between occupational and
  non-occupational NIHL

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Innovative Approach to Hearing Conservation

• Workers are empowered to manage their own noise
  exposures.
• Administrative controls become an effective
  alternative to engineering controls
• Only approach to allow the upstream prevention
  rather than downstream detection of NIHL.