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