IB-6 Physical Agents - Noise & Vibration Flashcards
outline the areas to consider in a vibration risk assessment
- identify the source of vibration & tasks
- identify workers at risk
- estimate exposure
- seek advice from suppliers of equipment
- measurement of vibration magnitude
- consider exposure limits
- health surveillance
- are additional controls needed
identify the risk factors associated with HAV (Hand Arm Vibration) syndrome
- exposure
- magnitude of exposure
- direction & frequency of vibration
- duration
- force needed
- cold or wet working conditions
- previous health conditions - circulatory problems
how do you estimate the Lepd (daily personal noiseexposure)
- measure the equivalent noise level at each machine -Leq. this can be done using an integrated sound meter - positioned at operators head
- how much time is spent completing each task
- these figures can be calculated using a logarithmic scale.- use ready reckoner or hse website based tool
what does noise induced hearing loss look like on a graph
threshold shift (db) 70 going up to -10 vs frequency (hz) 125 going across to 16k
4k dip shows hearing loss
outline the benefits & limitations of audiometry as part of a hearing conservation programme
benefits
- monitoring evidence of effectiveness of programme
- pre employment identification of pre existing conditions
- identification of early signs of noise induced hearing loss
- basis to defend claims of noise induced hearing loss
limitations
- not preventative
- information may trigger claims
- possible inaccurate data - make sure operatives are not exposed to high levels of noise prior to test (temporary threshold shift)
- dose not identify source of noise induced hearing loss
identify the different types of equipment that can be used to measure noise in the workplace
sound level meters
- used for spot checks & initial surveys
- identifies sound pressure on A weighted and C weighted matrices with analogue or digital readouts
- can be read by the eye
integrating sound level meter
- A weighted mode - equivalent daily noise exposure calculated.
- peak action level used to make noise measurements for the purpose of noise regulations
- measures the sound levels over a period of time then joins the. Together to calculate the average exposure
explain the purpose, design and construction characteristics of an acoustic enclosure
encloses the equipment
design considerations
- sound reduction of the panelling of the enclosure - to meet the octave band of the noise exposed
- protection of the internal absorbent lining
- robust construction
- sealing between the panel, floor and around penetrating ducts & pipes
- access for operation and maintenance
- robust locks to doors and hatches
- observation windows
- adequate internal space
- adequate lighting & ventilation
- flexible pipes
what is the purpose, design and construction of an acoustic haven
enclose the worker
design considerations
- noise reduction properties of the haven using an octave band analysis
- similar properties to a noise enclosure except that noise absorbent lining is not required
- observation windows
- adequate internal space
- adequate lighting & ventilation
- adequate seating
- inclusion of as many controls as possible
haven must be sealed from all sounds and locks fitted
identify the factors to be considered when completing a noise survey
- basic survey completed first
- noise levels (can you hear someone speak within 2 meters)
- who is at risk
- how will measurements be taken and for how long
- duration of exposure
- machine sources and associated tasks
- existing controls
- work pasterns
- results of previous tests and surveys
- group sampling
- mobile workers
If the exposure is at or exceeded the upper exposure action value then a more detailed survey will be needed using an ne’er grated sound level meters
outline the range of control measures to minimise the effects of WBV to drivers of heavy equipment
- consider controls for
- vehicle
- traffic routes
- individual
controls implemented on the vehicle - right for terrain & activities / suspension fitted / adjustable seats / tyres correctly inflated / maintained / vibration damping characteristics
controls implemented on traffic routes - avoid uneven surfaces / roadways maintained
controls implemented with driver - limit hours of exposure / rest breaks & shift rotation / trained on driving technique to avoid vibration / ensure exposure is kept below the threshold
what are the ill health effects of exposure to noise
- noise induced hearing loss - loss of sensitivity to sound in the speech range
- tinnitus
- threshold shift
- neuro psychological disturbances - headache / fatigue / insomnia
- cardiovascular system disturbances - hypertension & cardiac disease
- digestive disorders - peptic ulcers & colitis
what is threshold shift
is the reduction in a persons ability to hear it can be permanent or temporary. when the hair cells in the cochlea are fatigued and lay flat
noise induced hearing loss seen as a 4Kz dip - the amount of dip from a 0dB average level
outline the benefits and limitations of audiometry as part of a hearing conservation programme
audiometry is the process of scientifically quantifying hearing performance in order to detect a problem with the persons hearing
advantages
- early identification of individuals with hearing loss will allow them to be further protected to prevent deterioration
- early detection of poor controlled noise exposure - allow other workers to be protected
- negative test results confirm programme is working effectively
- establishment of pre employment baseline - prevention of claim
- compliance with legal regulations
disadvantages
- subjective - based on cooperation of the of test person
- reactive - confirms hearing loss after it has occurred
- inaccurate for technical reasons or headphone fit
- can be difficult to operate in practice where there are large numbers of workers to be tested
- can trigger claims
identify the signs and symptoms of HAVS
starts at the tip of the finger and with continued exposure can move to the base of the finger
- numbness and tingling in the finger
- reduced sense of touch & temperature
- difficult to feel and handle small objects
- periodic blanching attacks
- vibration induced white finger - finger feel numb as blood circulation returns fingers can be throbbing and red & painful
- joint pain
- carpel tunnel syndrome (compression of the nerves in the wrist)
- stiffness in hand & arm
those affected often have to give up outside activities
explain the meaning of whole body vibration and what work activties are exposed
is the shaking, jolting or vibration of the body which is transmitted to the worker through seated, standing or supporting surfaces
typical work activities - drivers of heavy vehicles / forklift trucks / operators of heavy machinery
