occupational noise
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TRANSCRIPT
OCCUPATIONAL NOISE
STACY ARVINNAGROUP 34TH YEAR 1ST SEM11 JANUARY 2011HYGIENE SUBJECT
SOUND VERSUS NOISE Sound is a pressure change detectable by the human ear.
The pitch ranges between 20 to 20,000 Hz.
The volume ranges between 0 to 140 dB.
Noise is a type of sound.
It carries no information.
It is random.
It is generally described as undesirable or unwanted sound.
AN EAR’S ANATOMYHOW WE HEAR?
Ear Outer ear -
directs sound waves
Middle ear - eardrum - hammer, anvil, stirrup
Inner ear - organ of corti, cochlea
OCCUPATIONAL NOISE Noise is defined as unwanted sound. Transit workers who operate, service, or
maintain vehicles, equipment, or facilities may be routinely exposed to high levels of noise.
Working in maintenance shops or repairing buses involves using loud machinery such as motors, grinders, saws, presses, pneumatic equipment and hand held tools can also generate high noise levels.
NOISE ON HEARING
Sound - produced vibrations enter the inner ear as waves.
Frequency - (pitch) number of vibrations per second; measured in hertz (Hz)
Intensity - loudness of the sound; measure in decibels (dB).
EFFECT OF OCCUPATIONAL NOISE Exposure to excessive noise levels at work can
result in two types of noise induced hearing loss (NIHL):
Temporary (conductive) hearing loss occurs when sound vibrations are blocked from reaching the inner ear. This may be due to wax buildup, an infection of the middle ear, or explosive sounds that damage the eardrum or middle ear. This type of hearing loss is reversible. The ear may recover on its own or it may be surgically corrected.
Permanent (sensineural) hearing loss occurs when cells and nerves in the inner ear are damaged. Individuals don’t realize they are experiencing hearing loss because it happens gradually. It cannot be corrected or reversed.
SIGNS AND SYMPTOMS OF HEARING LOSS
Ringing / buzzing in the ears Difficulty with high pitched sounds Problems with conversing with others Inability to hear consonants Raising the volume on the TV / radio
TYPES OF HEARING LOSS Middle ear hearing loss results from lack of
conduction. Impacted wax Broken ear drum
Inner ear hearing loss results from lack of neural connections.
Naturally due to aging Loud noises Disease
OCCUPATIONAL HEARING LOSS
Noise-Induced Hearing Loss or Noise-Induced Permanent Threshold Shift (NIPTS)Permanent sensor neural conditionCannot be treated or corrected medically Initially effects high frequencies
Industrial trough Speech recognition
Progresses to lower frequencies
EFFECT OF OCCUPATIONAL NOISE
Exposure to excessive noise levels at work can also result in:
Increased stress levels that may raise blood pressure and contribute to heart disease. High noise levels can also cause insomnia, fatigue, irritability, and decreased job performance.
Increased risk of accidents because high noise levels make it more difficult to hear other workers, to hear warnings or approaching vehicles, or to be heard by other workers.
Effects cardiovascular system Effects the nervous system Interferes with speech and concentration Causes annoyance, stress, and fatigue Reduces work efficiency Lowers morale Masks warning sounds
NON-AUDITORY EFFECTS OF NOISE
THRESHOLD SHIFTS
Temporary Threshold Shifts (TTS) Hearing returns to normal after noise exposure
Permanent Threshold Shifts (PTS) Repeated noise exposure without a return
to normal Standard Threshold Shifts (STS)
> 10 dB average loss in 2000, 3000, or 4000 Hz in either ear
NOISE LEVEL AND THE HUMAN RESPONSE
Pneumatic chipping and riveting 130dB(A)
Automatic punch press 110 dB(A)
Heavy lorries at 6m 90 dB(A)
Construction site - pneumatic drilling 90 dB(A)
NOISE MEASURING EQUIPMENT Sound level meters
Basic instrument to measure sound pressure variations in air
Noise dosimeter Combines sound pressure
and time for employee exposure monitoring
NOISE MEASURING EQUIPMENT
Octave band analyzer
Diagnostic tool to help find appropriate engineering controls to reduce noise levels
AUDIOMETRIC TESTING
A qualified person performs the hearing test, usually an audiologist.
The audiometers are calibrated to determine your threshold of hearing and changes (threshold shifts).
Must meet strict specified criteria A qualified person interprets the results of the
hearing test.
AUDIOMETRIC TESTING
Painless and short test to measure hearing
Establishes a baseline
Detects changes in hearing
Employee’s with exposure in excess of
85dB(A) over an 8 hour period
NOISE REDUCTION RATING
Defined as the maximum number of decibels (dB) that the hearing protector will reduce the sound level when worn
NRR must be on the hearing protector package. NRR example for A-weighted data
Estimated exposure (dBA) = TWA (dBA) - (NRR - 7)
HEARING CONSERVATION
Bulldozer: 85dBA
Quite Room: 30 dBA
Normal Conversation: 50 dBA
Normal City Noises: 65 dBA
Artillery/Good Rock Band: 120 dBA
HEARING PROTECTION
Three ways to protect your hearing:Engineering controlsAdministrative controlsPersonal Protective Devices
Engineering Controls Engineering controls reduce noise at its source.
Examples include: enclosing noisy machinery, fans, or motors, or
moving them away from workers controlling vibration by damping or by tightening,
lubricating, or isolating vibrating parts replacing loud machines with quiet machines installing sound barriers or sound- absorbing
materials Equipment and exhaust
ENGINEERING CONTROLS
ADMINISTRATIVE CONTROLS
Decreasing the exposure time
Limiting the number of personnel
exposed
Arranging a work roster system
EUROPEAN COMMUNITY 1990 REGULATIONS
Objectives Protect workers from risks to their hearing caused by
noise. Prevent hearing loss and deafness as a result of
exposure to noise at work.
Legal requirements placed on employers Identify noise problems and if noise levels are above
85dB(A), measurements must be taken and assessed by a competent person. Such measurements should be repeated at appropriate intervals.
EUROPEAN COMMUNITY 1990 REGULATIONS General duty to reduce the level of noise exposure by
engineering or administrative means.
If noise level is above 85dB(A): Inform employees of the noise levels present and
measures taken to reduce exposure.
Make ear protection available and provide training in its use
Hearing checks must be made available to employees exposed to noise levels in excess of 85dB(A) over an 8 hour period
EUROPEAN COMMUNITY 1990 REGULATIONS
If noise level is above 90dB(A) the noise requirements for 85dB(A) apply plus: Identify reasons for excess noise and put a plan in place to
reduce. Identify and clearly designate hearing conservation zones. Ear protection must be worn and its use supervised. Employees must be trained in the hazards of noise and the
correct use of hearing protection.
NOISE LIMIT No employee shall be exposed above the
permissible exposure level (PEL).
PEL = 90 dBA for a 8-hour time-weighted average (TWA)
Feasible administrative or engineering controls are required.
Hearing protection is required to protect the employee to the PEL.
NOISE ACTION LIMIT Action Level (AL) = 85 dBA for a 8-hour TWA
Determined without regard to hearing protector attenuation
Hearing Conservation Program (HCP) required
Hearing protection devices must be available
MONITORING Strategy to identify all employees who could be
exposed above AL (85 dBA)
Conduct representative sampling
Each job classification
All shifts
Repeat monitoring when:
Additional employees are exposed
Hearing protectors are inadequate
TRAINING Must be annual Must include:
Effects of noise on hearing Purpose of hearing protectors Instruction in protector hearing protector selection,
fitting, use and care Purpose of audiometric test and explanation of the
procedures and results
POSTING THE STANDARD
The employer shall make available to affected employees or their representatives copies of the standard.
The employer shall also post a copy of the standard in the workplace.
RECORDKEEPING Provide employee and DOL access and transfer
records to successor employer
Noise measurements: > 2 years
Audiometric tests > employment duration:
Name, job classification and dBA-TWA
Date, examiner’s name and calibration date
Background measurements of audiometric test room
PERSONAL PROTECTIVE
DEVICES Hearing protective devices (HPDs) may be
used as a last resort, if engineering or administrative controls are ineffective or not feasible. Examples include earmuffs and earplugs. HPDs are required to be labeled with a noise reduction ratio (NRR). The NRR is the
HEARING PROTECTORS Shall be available to “action level” employees Shall be required for those employees:
Exposed at or above 90 dBA
Exposed at or above 85 dBA (without an audiometric baseline)
HEARING PROTECTORS
Provided at no cost to the employee
Selected from a variety of types and brands
Properly fitted
Replaced as necessary
HEARING PROTECTORS“EAR PLUGS”
These devices fit into the ear canal between the outer and middle ear and block the sound from reaching the sensitive inner ear.
(i) Made of foam material that is rolled and inserted, expands to fit snugly and can be custom made.
(ii) Wash hands, roll and compress into a cylinder. Reach one hand around the back of the head and pull ear up and out. Insert into the ear canal. Hold in place until it begins to expand and excludes noise.
(iii) Inspect before insertion and discard if damaged or dirty.
(iv) Small, inexpensive, portable, comfortable in warn weather, disposable, can hear others speaking.
(v) Requires a good fit, cannot be inserted with dirty hands, cannot be worn with ear infections, might become loose over time.
“EAR PLUGS”
HEARING PROTECTORS“EAR MUFFS”
This style protector consists of cups which fit over the entire outer ear to help seal out noise. May be connected to the hard hat or held together by a head band.
(i) Cushioned caps connected by a spring loaded headband.
(ii) Adjust the headband to ensure that the seals are in complete contact with the head. Ensure the ear cup fits over the entire outer ear. Wear eyeglass frames with temple cushions that will not break the seal of the muffs.
(iii) Wipe cushions when they become soiled. Replace if stiff, worn, cut or torn.
(iv) Can be worn with ear plugs for extreme noise exposure. Reduction of approximately 50 dBA. Easy to put on and remove. Can be worn despite ear infections.
(v) Bulky and can be uncomfortable in warm weather.
“EAR MUFFS”
PROTECTOR ATTENUATION Hearing protectors shall:
For overexposed employees
Attenuate < 90 dBA 8-hr TWA
For employees with an STS
Attenuate < 85 dBA 8-hr TWA
Whenever noise exposures increase
Be reevaluated to determine adequacy
WHAT IS NOISE Noise is an unpleasant / unwanted
sound Hearing and how noise effects it Types of noise
continuous impulse
Side effects of noise loss of hearing stress accidents behavioral effects negative impact on health
SUMMARY
Know the source of harmful noise
Use engineering and administrative
controls to avoid exposure to noise
Obey posted high noise area signs
Wear hearing protection properly