lecture 6-_noise_hazard
DESCRIPTION
TRANSCRIPT
Topic 5:
Noise HazardTopic Learning Outcome :
1)Explains the characteristic of sound and vibration and its risk.
2) Describe the identifying and assessing of noise hazard inindustries and its control and prevention strategies.
TOPIC
CONTENTs: 5.1 Characteristic of sound and vibration
5.2 Hazard level and its risk
5.3 Identifying and assessing hazardous noise inindustries
5.4 Noise hazard control and prevention strategies.
5.1 Characteristic of sound and vibration
Sound is any change in pressure that can be detected by ear.
Noise is unwanted or damaging sound that may damage our hearing .
dB (DECIBEL): The unit used toexpress the intensity of sound.The decibel scale is alogarithmic scale in which thethreshold of discomfort isbetween 85 and 95 dB and thethreshold for pain is between120 and 140 dB .
Frequency
dB
Acceptable Noise(dBA)
Location EffectsMaximum Leq(dBA)
Time (hours) Time of day
Bedroomsleep disturbance, annoyance
30 8 night
Living areaannoyance, speech interference
50 16 day
Outdoor living area
moderate annoyance
50 16 day
Outdoor living area
serious annoyance
55 16 day
Outdoor living area
sleep disturbance, with open windows
45 8 night
School classroom
speech interference, communication disturbance
35 8 day
Hospitals patient rooms
sleep disturbance, communication interference
30 - 35 8 day and night
5.1 Characteristic of sound and vibrationTypes of sound signals The types of sound has a bearing on how it is to be measured, whattype of sound level meter setting should be used and what descriptorsand other data should be presented.
5.2 Hazard level and its risk
According to Factories and Machinery (Noise Exposure) Regulation1989, Permissible Exposure limit : Noise level for 8 hour shift not exceeding equivalent steady
sound level 0f 90 db. Intermittent noise not exceeding 115dB at any time. Impulsive noise not exceeding a peak sound pressure level of
140 dB.
Safe
85dB
90dB
115dB 130dB
Permissible
Exposure limitDanger,
Disclosure is
prohibitedThreshold
of painHearing
loss
5.2 Hazard level and its risk
Caution!!
Deafness
caused by
noise can not
be cured
5.3 Identifying and assessing hazardous noise in industries
Noise identification and assessment may be simple or complex,depending on the type of workplaces, number of workers andthe information already available regarding noise exposurelevel.
The general aim of a noise assessment is to:• Identify all persons likely to be exposed to excessive noise.• Obtain information on noise sources and associated work
practices.• Check the effectiveness of measures taken to reduce noise
exposure or the risks from noise exposure.• Help choose appropriate personal hearing protectors for
persons exposed to risks from excessive noise; and• Define hearing protection areas at work.
5.3 Identifying and assessing hazardous noise in industries
Identifying and assessing hazardous noise in theworkplace involve :1) Conduct noise survey2) Audiometric testing – measure thethreshold of employees.3) Keeping record for individual employees4)Follow up on the critical
Audiometric
testing
equipment
5.3 Identifying and assessing hazardous noise in industries
Types of
equipments used
in measuring
sound
5.3 Identifying and assessing hazardous noise in industries
.
Example of Noise
hazard Identification
checklist
5.3 Identifying and assessing hazardous noise in industries
.Example of Noise Mapping
5.4 Noise hazard control and prevention strategies.
When reducing noise exposure, preference is given to engineering controls,then administrative controls and finally the use of appropriate PPE.
Engineering control - Must be considered during the design stage of a new facility or the expansion of facility
Substitution • Replace noisy equipment with quieter
Modification • Modify the way in which the equipment operates so that it generates less noise.
Isolation • Having them work in enclosed room.•Segregate noisy areas with sound barriers
Maintenance •Maintenance of equipment and the engineering controls that have been implemented is very important or the improvements in noise level will be lost.
5.4 Noise hazard control and prevention strategies.
Administrative control
Rotating work schedules or changing production schedules
• purposely to have amount of time that a worker is exposed to noise is within acceptable limits
Provision of training • Noise awareness training
Warning sign • Warning sign at all entrances to the high noise area
Conducting Audiometric test
• A test to determine employees hearing threshold or ability
PPE Providing appropriatePPE
• if reductions in noise level and exposure time have not reduced, then appropriate hearing protection must be provided according to the standard