Mine Safety and Health Occupational Noise Exposure Safety

Mine Safety and Health Occupational Noise Exposure Safety. Works!

OBJECTIVES • 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.

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.

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.

What is Noise? • Energy • Pressure changes in a medium (air) caused by vibration or turbulence • Pressure produces wave motion from source • Amplitude = Loudness = Decibels = d. B 60 d. B = Average Speaking Voice • Frequency = Cycles per Second = Hertz = Hz 1000 Hz = 1 Kilohertz = 1 k. Hz = Human Voice

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

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 d. B (just audible) to 140 d. B (causes pain) 80 d. B(A) 8 hour TWA will effect some 100 d. B(A) 8 hour TWA will effect all

Mine Safety and Health - Part 62 Occupational Noise Exposure • Establishes the Permissible Exposure Limit (PEL) of 90 d. B(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 d. B(A) or below. • Must assure that no miner is exposed to sound levels exceeding 115 d. B(A)

Mine Safety and Health - Part 62 Occupational Noise Exposure • Administer a Hearing Conservation Program (HCP) whenever the 8 Hour TWA = 85 d. B(A) or greater! • For Various Extended Workshifts, the allowable noise exposure decreases.

Major Requirements of a HCP • • • Exposure Monitoring Employee Notification Audiometric testing Hearing Protectors Employee Training Recordkeeping

Monitoring • Required where exposure may equal or exceed 85 d. B(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

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 >= 25 d. B in either ear

Comparing Baseline and Annual Audiograms • Compare the latest audiogram with the oldest • Compute differences of test results at : 2 k. Hz, 3 k. Hz and 4 k. Hz • Notify employee within 10 days, of hearing loss when > 10 d. B(A), also known as a Standard Threshold Shift (STS) • Retrain employee on hearing protection

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 d. B Standard Threshold Shift - YES MSHA Recordable - NO

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

Demo • With clean hands * insert a foam ear plug into one of your ears and have your partner observe. If you can not wear 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!

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

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

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)

Noise Controls If > 100 d. B You Must Reduce by 3 d. B • Acoustical Design – Noise ~ Energy (HP) ~ 1 x 10 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