Mine Safety and Health Occupational Noise Exposure

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Mine Safety and Health Occupational Noise Exposure

• SafetyWorks!

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O B J E C T I V E S

• Background information on noise
• Review of regulation
• Identify the major requirements for a
  
  
  
  
  hearing conservation program.
• Demonstrate the proper way to insert
  or wear hearing protectors.
• Illustrate the preferred methods to reduce
  noise.

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• YOUR EARS HAVE NO PROTECTION
• Noise destroys your hearing little by little.
• Exposure to noise occurs on and off the job.
• Your ears typically recover from exposures
  to
• low level noises.
• However, permanent damage may occur from even a
  single exposure to very loud noises.

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• Noise Effects Us In Other Ways
• Noise is Psychologically Stressful
• Noise may distract our attention and cause
• Accidents, Misunderstandings, Poor Performance,
  Fatigue and General Anxiety.
• NIOSH is studying the health effects of
  chemical exposures (solvents) combined with
  excessive noise exposures.

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What is Noise?

• Energy
• Pressure changes in a medium (air) caused by
  vibration or turbulence
• Pressure produces wave motion from source
• Amplitude Loudness Decibels dB
• 60 dB Average Speaking Voice
• Frequency Cycles per Second Hertz Hz
• 1000 Hz 1 Kilohertz 1 kHz Human Voice

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How is Noise Measured?

• Noise is measured in decibels (dB) at a certain
  scale, such as A or C.
• The decibel scale is logarithmic
• That means, with a 5dB exchange rate, 95 dB is
  100 more noise than 90 dB!

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Human Hearing Ranges

• 20 Hz (low rumble) to 20,000 Hz (whine)
• Speech Between 500 Hz to 2000 Hz
• Average Hearing Loss at 4000 Hz and up
• 0 dB (just audible) to 140 dB (causes pain)
• 80 dB(A) 8 hour TWA will effect some
• 100 dB(A) 8 hour TWA will effect all

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Mine Safety and Health - Part 62 Occupational
Noise Exposure

• Establishes the Permissible Exposure Limit (PEL)
  of 90 dB(A) as an 8 hour time weighted average
  (TWA)
• Mandates engineering or other controls (but not
  ear protectors) to be used to reduce noise levels
  to 90 dB(A) or below.
• Must assure that no miner is exposed to sound
  levels exceeding 115 dB(A)

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Mine Safety and Health - Part 62 Occupational
Noise Exposure

• Administer a Hearing Conservation Program (HCP)
  whenever the
• 8 Hour TWA 85 dB(A) or greater!
• For Various Extended Workshifts, the allowable
  noise exposure decreases.

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Major Requirements of a HCP

• Exposure Monitoring
• Employee Notification
• Audiometric testing
• Hearing Protectors
• Employee Training
• Recordkeeping

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Monitoring

• Required where exposure may equal or exceed 85
  dB(A) as an 8 hr. TWA
• Measure 8 hr. TWA using
• Calibrated type I or II integrating dosimeter
• Remonitor when change or new employee
• Employees may observe the monitoring
• Notify employees of monitoring results

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Audiometric Testing

• Baseline test (within 6 months of exposure)
• Annual audiograms (compared to baseline)
• Performed by licensed audiologist or doctor
• Inform employees in writing of results if
• Abnormal test results
• Standard Threshold Shift (STS) detected
• In MSHA Form 7000-1 when average loss gt 25 dB in
  either ear

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Comparing Baseline and Annual Audiograms

• Compare the latest audiogram with the oldest
• Compute differences of test results at 2
  kHz, 3 kHz and 4 kHz
• Notify employee within 10 days, of hearing loss
  when gt 10 dB(A), also known as a Standard
  Threshold Shift (STS)
• Retrain employee on hearing protection

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Audiogram Comparison for Mr. I. Ben Listnen

• Right Ear 500 1000 2000 3000 4000 6000
• 9/10/82 10 5 15 10
  20 15
• 9/16/98 15 20 35 25 45
  35
• difference 20 15
  25
• average 20 15 25 / 3 60/3 20 dB
• Standard Threshold Shift - YES
• MSHA Recordable - NO

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Hearing Protectors

• Noise Reduction Ratings (NRR) - adjust by the
  following formula (NRR-7)/2
• Foam Plugs
• small, good in heat, least costly, good reduction
• maybe painful, spread infections or impact wax
• Ear Muffs
• easy, visually observable, less infections
• less effective with glasses, hair or head motion

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Demo

• With clean hands insert a foam ear plug into
  one of your ears and have your partner observe.
• If you can not wear ear plugs or do not want to
  participate with plugs, please do the exercise
  with the ear muffs. Thanks!
• If you are not well today or have touched
  someone who is not well, please wash your hands
  before doing this exercise!

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Employee Training

• Conduct annually on
• Effects of noise on hearing
• Reasons for annual audiograms
• Proper selection, use and care of protectors
• Pros and Cons of various protectors
• Other training may include
• Explanation of audiometric test results
• Methods to control noise

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Recordkeeping

• Required
• Audiograms - Retain for duration of employment,
  plus at least 6 months
• 62.171 Audiometric test procedures
• Recommended
• Training dates/content/enrollment
• Personal/Area Monitoring Records

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The Best Ways to Reduce Hearing Loss (in order of
priority)

• Eliminate the source
• Substitute a quieter process
• Engineer sound controls on the source
• Isolate the source by distance
• Shield the source
• Provide sound dampening materials
• Reduce exposure times
• Hearing protective devices (last option)

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Noise Controls

• If gt 100 dB You Must Reduce by 3 dB
• Acoustical Design
• Noise Energy (HP) 1x10 8 Velocity
• Energy can be Transmitted, Reflected or Absorbed
• Material rated by noise reduction coefficient
  (NRC)
• Closed Cell Foam / Air Gap / Sheet rock
• Optimal thickness 1/4 wavelength
• Resonance
• RPM / Hz resonant frequency
• Mufflers / Silencers / Reflection Chambers
• Active Cancellation Systems