Noise&Vibration_Hazard

• Sound


  Any change in pressure that can be detected by the ear
• Noise


  Unwanted sound
• Decibel (dB)


  Unit of measurement used for discussing the level of sound and what noise levels are hazardous
• The OSHA Noise Standard requires monitoring instruments to be capable of measuring between 80 and 130 dBA
• Decibel levels for common sounds

  • Normal conversation (60 dBA)
  • OSHA level for required hearing protection (85 dBA)
  • Power saw (90 dBA)
  • Chain saw (90 dBA)
  • Passing truck (100 dBA)
  • Compressor (100 dBA)
  • Rock concert (110-120 dBA)
  • Shotgun (140 dBA)
  • Jet aircraft (150 dBA)
• Threshold of hearing


  The weakest sound that can be heard by a healthy human ear in a quiet setting (10 dBA)
• Threshold of pain


  The maximum level of sound that can be perceived without experiencing pain (140 dBA)
• Hearing loss


  • Impairment that interferes with the reception of sound and with the understanding of speech
  • The most important frequencies for speech understanding are those between 200 and 5,000 hertz
• A young person with normal hearing can detect sounds with a frequency range that extends from 20 to 20,000 hertz
• Hearing loss almost always occurs first at about 4,000 Hz
• Occupational noise-induced hearing loss

  Occurs over a period of several years' exposure to continuous or intermittent loud noise
• Occupational noise-induced hearing loss almost always affects the hair cells in both inner ears, but occasionally the effect can be asymmetric
• Tinnitus can be a result of the aging process and might not disappear, and might occur almost continuously
• Factors that affect the risk of hearing loss


  • Intensity of the noise
  • Type of noise (wide band, narrow band, or impulse)
  • Duration of daily exposure
  • Total duration of exposure (number of years)
  • Age
• Exposure to sound levels below 80 dBA


  Generally considered safe
• Exposure to noise levels higher than 80 dBA


  Should be protected against through the use of appropriate personal protective devices
• To decrease the risk of hearing loss, exposure to noise should be limited to a maximum eight-hour time-weighted average of 90 dBA
• General rules for dealing with noise in the workplace

  • Exposures of less than 80 dBA may be considered safe for the purpose of risk assessment
  • A level of 90 dBA should be considered the maximum limit of continuous exposure over eight-hour days without protection
  • Continuous exposure to levels of 115 dBA and higher should not be allowed
  • Impulse noise should be limited to 140 dBA per eight-hour day for continuous exposure
• OSHA Hearing Conservation Standard

  Requires employers to implement hearing conservation programs in any work setting where employees are exposed to an eight-hour time-weighted average of 85 dBA and above
• OSHA's Hearing Conservation Standard

  1. Monitoring noise levels

  2. Medical surveillance

  3. Noise controls

  4. Personal protective equipment (PPE)

  5. Education and training
• Noise assessment


  • Conducting periodic noise surveys
  • Conducting periodic audiometric tests
  • Record keeping
  • Follow-up action
• Noise hazards must be reduced to acceptable levels using personal protective equipment in addition to administrative and engineering controls
• Hearing Conservation Standard


  29 CFR 1910.95
• Hearing Conservation Standard Requirements

  1. Education and training

  2. Monitor noise levels

  3. Personal protection

  4. Medical surveillance
• Education and training


  • Employees understand: (1) how the ear works, (2) how to interpret audiometric test results, (3) how to select and use personal protective devices
• Noise Assessment


  1. Conducting periodic noise surveys

  2. Conducting periodic audiometric tests

  3. Record keeping

  4. Follow-up action
• Noise Surveys


  Measuring noise levels at different locations using sound level meters and dosimeters
• Audiometric Testing


  Measures hearing threshold of employees to detect changes and identify hearing loss
• Follow-up after Audiometric Testing

  1. Administer retest

  2. Change/improve personal protection

  3. Conduct new noise survey

  4. Test other employees
• Employee Training


  Understand noise dangers, recognize harmful exposures, evaluate noise levels, take action to protect hearing
• Hearing Protection Devices (HPDs)

  • Passive (earplugs, earmuffs)
  • Active (noise-attenuating helmets with noise cancellation and communication features)
• Earplugs


  • Rubber/plastic devices that fit snugly in ear canal, require proper fitting, effective up to 95 dB for 8 hours
• Earmuffs


  • Cover entire ear and bony areas, provide greater protection than improperly fitted earplugs, can cause headaches and discomfort
• Vibration can have adverse effects besides noise, including injury to skull, bones, organs, and metal fatigue
• Vibration is transmitted more easily through solid materials than air, and can cause equipment damage and personnel injury
• Vibration from tools can lead to conditions like Raynaud's phenomenon, arthritis, bursitis, and blood vessel blockage
• Controlling Vibration


  1. Select low-vibration equipment

  2. Mount equipment on firm foundations

  3. Use vibration isolators and dampers