Hazardous noise can destroy the ability to hear
clearly and can also make it more difficult to hear sounds necessary for
working safely, such as instructions or warning signals.
Managing the risks related to noise will assist
in:
- protecting workers from hearing loss and
disabling tinnitus (ringing in the ears or head)
- improving the conditions for communication
and hearing warning sounds
- creating a less stressful and more
productive work environment.
1.1 Who
has health and safety duties in relation to noise?
A person conducting a business or undertaking
has the primary duty under the WHS Act to ensure, so far as is reasonably
practicable, that workers and other persons are not exposed to health and
safety risks arising from the business or undertaking.
A person conducting a business or undertaking
has more specific obligations under the WHS Regulations to manage the risks of hearing
loss associated with noise at the workplace, including:
·
ensuring that the noise a worker is exposed to
at the workplace does not exceed the exposure standard for noise
·
providing audiometric testing to a worker who
is frequently required to use personal hearing protectors to protect the worker
from hearing loss associated with noise that exceeds the exposure standard.
Designers, manufacturers,
suppliers, importers and installers of
plant or structures that could be used for work must ensure, so far as is
reasonably practicable, that the plant or structure is without risks to health
and safety. Designers and manufacturers of plant must ensure the plant is
designed and manufactured so that its noise emission is as low as reasonably
practicable.
Designers,
manufacturers, suppliers and importers must also provide information about the noise
emission values of the plant and any conditions necessary for minimising the
risk of hearing loss and other harm (see Chapter 7 of this Code).
Officers,
such as company directors, have a duty to exercise due diligence to ensure that
the business or undertaking complies with the WHS Act and Regulations. This
includes taking reasonable steps to ensure that the business or undertaking has
and uses appropriate resources and processes to eliminate or minimise risks
that arise from noise.
Workers
have a duty
to take reasonable care for their own health and safety and that they do not
adversely affect the health and safety of other persons. Workers must comply
with any reasonable instruction and cooperate with any reasonable policy or
procedure relating to health and safety at the workplace. For example, if
personal hearing protectors are provided by the person conducting the business
or undertaking, the worker must use them in accordance with the information,
instruction and training provided on their use.
1.2 The
meaning of key terms
Exposure
standard for noise is defined in the WHS Regulations as an LAeq,8h of 85 dB(A) or an LC,peak of 140 dB(C). There are two parts to the
exposure standard for noise because noise can either cause gradual hearing loss
over a period of time or be so loud that it causes immediate hearing loss.
LAeq,8h means the
eight hour equivalent continuous A-weighted sound pressure level in decibels,
referenced to 20 micropascals, determined in accordance with AS/NZS 1269.1. This
is related to the total amount of noise energy a person is exposed to in the
course of their working day. It takes account of both the noise level and the
length of time the person is exposed to it. An unacceptable risk of hearing
loss occurs at LAeq,8h values above
85 dB(A).
LC,peak means the
C-weighted peak sound pressure level in decibels, referenced to 20 micropascals,
determined in accordance with AS/NZS 1269.1. It usually relates to loud, sudden
noises such as a gunshot or hammering. LC,peak values above
140 dB(C) can cause immediate damage to hearing.
Hazardous
noise in relation to hearing loss means noise that
exceeds the exposure standard for noise in the workplace.
Risk control means taking
action to first eliminate health and safety risks so far as is reasonably
practicable, and if that is not possible, minimising the risks so far as is
reasonably practicable. Eliminating a hazard will also eliminate any risks
associated with that hazard.
1.3 What is required to manage
the risks of hearing loss?
Regulation 34-38: In order to
manage risk under the WHS Regulations, a duty holder must:
a) identify reasonably foreseeable hazards that
could give rise to the risk
b) eliminate the risk so far as is reasonably
practicable
c) if it is not reasonably practicable to
eliminate the risk – minimise the risk so far as is reasonably practicable by
implementing control measures in accordance with the hierarchy of control
d) maintain the implemented control measure so
that it remains effective
d) review, and if necessary revise, risk control
measures so as to maintain, so far as is reasonably practicable, a work
environment that is without risks to health and safety.
This Code
provides guidance on how to manage the risks of hearing loss associated with
noise by following a systematic process that involves:
- identifying sources of noise that may cause or
contribute to hearing loss,
- if necessary, assessing the risks associated with
these hazards,
- implementing risk control measures
- reviewing risk control measures.
Guidance
on the general risk management process is available in the Code of Practice: How to Manage Work Health and Safety Risks.
Consulting your
workers
Consultation involves sharing of information, giving workers a
reasonable opportunity to express views and taking those views into account
before making decisions on health and safety matters.
Section 47: The WHS
Act requires that you consult, so far as is reasonably practicable, with
workers who carry out work for you who are (or are likely to be) directly
affected by a work health and safety matter.
Section
48: If the workers are represented by a health and safety
representative, the consultation must involve that representative.
Consultation with workers and their health and safety
representatives is required at each step of the risk management process. By
drawing on the experience, knowledge and ideas of your workers you are more
likely to identify all hazards and choose effective control measures.
You
must also consult your workers when proposing to make any changes that may
affect their health and safety, for example when planning to buy new machinery
or equipment.
Health and safety representatives must have access to
relevant information such as noise exposure data and potential control options.
If you have a health and safety committee, you should
engage the committee in the process as well.
Consulting,
co-operating and co-ordinating activities with other duty holders
Section
46: The WHS Act requires that you consult, co-operate and co-ordinate
activities with all other persons who have a work health or safety duty in
relation to the same matter, so far as is reasonably practicable.
Sometimes you may share responsibility for a health and safety
matter with other business operators who are involved in the same activities or
who share the same workplace. In these situations, you should exchange
information to find out who is doing what and work together in a co-operative
and co-ordinated way so that all risks are eliminated or minimised as far as
reasonably practicable.
For example,
if you own or manage an on-hire business and your workers work at other
workplaces then you must consult the host business so far as is reasonably
practicable to determine if your workers could be exposed to hazardous noise
and agree on what you each will do to control any associated risks.
Further guidance is available in
the Code of Practice: Work Health and
Safety Consultation, Co-operation and Co-ordination.
2.1 How does hearing loss
occur?
Hazardous noise
affects the functioning of the inner ear, which may cause temporary hearing
loss. After a period of time away from noise, hearing may be restored. With further
exposure to hazardous noise, the ear will gradually lose its ability to recover
and the hearing loss will become permanent.
Permanent hearing
loss can also occur suddenly if a person is exposed to very loud impact or
explosive sounds. This type of damage is known as acoustic trauma.
Permanent hearing
loss results from the destruction of hair cells in the inner ear. These cells
cannot be replaced or repaired by any presently known medical treatments or
technology.
Usually, hazardous noise
first affects the ability to hear high-frequency (high-pitched) sounds. This
means that even though a person can still hear some sounds, conversation will
start to sound ‘muffled’ and a person may find it difficult to understand what
is being said.
Communication difficulties
occur especially when there are competing background noises. Modern hearing
aids may improve the ability to hear speech but they are unable to completely
restore the clarity of the full hearing function.
Workers exposed to hazardous noise may also experience
tinnitus, which could become permanent. When severe, it may disrupt sleep, reduce
concentration, make people extremely irritable and lead to depression.
The degree of
hearing loss that occurs is dependent on how loud the noise is, how long someone
is exposed to it and, to some extent, individual susceptibility. The frequency
or pitch can also have some effect on hearing loss, since high-pitched sounds
are more damaging than low-pitched ones.
Exposure to a number of
common industrial chemicals and some medications can also cause hearing loss or
exacerbate the effects of noise on hearing. These substances are called
ototoxic substances.
Ototoxic substances absorbed
into the bloodstream may damage the cochlea in the inner ear and/or the
auditory pathways to the brain, leading to hearing loss and tinnitus. Hearing loss
is more likely if exposure is to a combination of substances or a combination
of the substance and noise.
There is also some evidence that
exposure to hand transmitted vibrations can exacerbate the effects of noise on
hearing.
Further
information on these other causes of hearing loss is provided in Appendix A.
2.2 How much noise is too much?
Whether the exposure standard of 85 dB(A) averaged over eight hours is
exceeded depends on the level of noise involved and how long workers are
exposed to it.
Peak noise levels greater than 140 dB(C) usually occur with impact or
explosive noise such as sledge-hammering or a gun shot. Any exposure above this
peak can create almost instant damage to hearing.
Decibels are not like normal numbers. They can’t be added or subtracted
in the normal way. The decibel scale is logarithmic. On this scale, an increase
of 3 dB therefore represents a doubling or twice as much sound energy. This
means that the length of time a worker could be exposed to the noise is reduced
by half for every 3 dB increase in noise level if the same noise energy is to
be received.
Table 1 below demonstrates the length of time a person without hearing
protectors can be exposed before the standard is exceeded.
Table 1:
Equivalent Noise Exposures
LAeq,8h = 85 dB(A)
|
|
Noise
Level dB(A)
|
Exposure
Time
|
80
|
|
82
|
12hours1
|
85
|
8 hours
|
88
|
4 hours
|
91
|
2 hours
|
94
|
1 hour
|
97
|
30 minutes
|
100
|
15 minutes
|
103
|
7.5 minutes
|
106
|
3.8 minutes
|
109
|
1.9 minutes
|
112
|
57 seconds
|
115
|
28.8 seconds
|
118
|
14.4 seconds
|
121
|
7.2 seconds
|
124
|
3.6 seconds
|
127
|
1.8 seconds
|
130
|
0.9 seconds
|
Essentially, a worker who is exposed to 85 dB(A) for 8 hours receives
the same noise energy as someone exposed to 88 dB(A) for 4 hours, with the
balance of the day in a very quiet environment. In both cases the exposure
standard is not being exceeded. However, being exposed to 88 dB(A) for more
than 4 hours would mean that the standard is exceeded. Similarly, if a worker
is using a machine that generates 121 dB(A) then the exposure standard would be
exceeded after only 7.2 seconds.
The WHS Regulations set
the exposure standard for noise at an LAeq,8h of 85 dB(A) and a peak noise level at 140 dB(C), which protects most but
not all people. Therefore, workplace noise should be kept lower than the
exposure standard for noise if reasonably practicable.
2.3 Other
effects of noise
Noise at levels that do
not damage hearing can have other adverse health effects. This can arise when
noise chronically interferes with concentration and communication. Persistent
noise stress can increase the risk of fatigue and cardiovascular disorders
including high blood pressure and heart disease.
Although safe levels to
guard against these effects have not yet been fully determined, as a guide, the
risk of adverse health effects can be minimised by keeping noise levels below:
- 50 dB(A) where work is being carried out
that requires high concentration or
effortless conversation
- 70 dB(A) where more routine work is being
carried out that requires speed or attentiveness or where it is important
to carry on conversations.
These levels include the
noise from other work being carried out within the workplace.
To work safely, workers
must be able to hear warning signals above any other noise (ambient noise) at
the workplace. For reversing alarms on mobile plant, the guidance in ISO:9533: 2010
Earth-moving machinery – Machine-mounted
audible travel alarms and forward horns – Test methods and performance criteria
should be followed. This requires the noise level of the alarm at potential
reception points to be at least as high as the noise from the engine under high
idle.
For other situations, the
levels needed are higher – at least 65 dB(A) and more than 15 dB(A) greater
than the ambient noise level at any position in the signal reception area. More
detailed guidance on assessing the audibility of warning signals can be found
in ISO 7731:2003 Ergonomics – Danger signals for public and work areas – Auditory danger
signals.
The potential for noise to be hazardous
is not always obvious. Hazard identification is a way of finding out which work
activities have the potential to contribute to hearing loss or other harm
caused by noise.
Exposure
to noise is cumulative and a worker may perform a number of noisy work
activities over time which, in combination, may expose the worker to hazardous
noise.
3.1 How to find noise hazards
You may not need specialist skills to
identify sources of hazardous noise, but you must undertake the process in
consultation with your workers and their health and safety representatives. As
a guide, if you need to raise your voice to communicate with someone about one
metre away, the noise is likely to be hazardous to hearing.
A
checklist is provided in Appendix B to help you further with this process.
Inspect the workplace
Regularly
walking around the workplace, talking to workers and observing how things are
done can help you identify noise hazards. Find out where noise is coming from
and which tasks or processes produce noise. Take immediate action to control
noise where this is possible, for example fix loose panels that are vibrating
and rattling during machine operation.
Review available information
Information
regarding noise levels from the manufacturers or suppliers of plant and
equipment used at the workplace should be obtained.
Information
and advice about hazards and risks relevant to particular industries and work
activities is also available from regulators, industry associations, unions,
technical specialists and safety consultants.
You
should check whether any workers’ compensation claims have been made for
hearing loss and if any hearing loss or tinnitus has been found during repeat
audiometric testing. If a worker’s hearing has been affected and has been
attributed to a particular task, then a hazard may exist that could affect other
workers.
Table
2 below lists common noise sources and their typical sound levels which can be
used to compare whether noise in the workplace sounds as loud as or louder than
85 dB(A).
3.2 What happens next?
In consultation with your workers and
health and safety representatives, make a list of all noisy activities that may
pose a risk to the health and safety of persons at the workplace. If you have answered
‘yes’ to any of the questions in Appendix B, it is likely that your workers are
being exposed to hazardous noise. If you are unsure about the level of exposure
or how to eliminate or minimise the risks effectively, you should take the next
step to assess the risks of hearing loss.
4.1 When should a risk assessment be conducted?
If
you have identified any noisy activities that may expose your workers or other
people at your workplace to hazardous noise then, unless you can reduce the
exposures to below the standard immediately, you should assess the risks by
carrying out a noise assessment.
A noise assessment will help you:
·
identify which workers are at risk of hearing
loss
·
determine what noise sources and processes are
causing that risk
·
identify if and what kind of noise control
measures could be implemented
·
check the effectiveness of existing control
measures.
A noise assessment
may not always need measurement. For example, if only one activity at the
workplace – the use of a single machine – involves noise above 85 dB(A) and the
manufacturer has provided information about the machine’s noise levels when it
is operated in particular ways, then a sufficient assessment can be made
without measurement. More complex situations may require measurement to
accurately determine a worker’s exposure to noise, such as workplaces with
variable noise levels over a shift and jobs where workers move in and out of noisy
areas.
4.2 Who
can do a noise assessment?
A noise assessment should be done by a
competent person in accordance with the procedures in AS/NZS 1269.1 Measurement and assessment of noise immission
and exposure. The more complex the situation, the more knowledgeable and
experienced the person needs to be.
A
competent person is one who has accurately calibrated noise measuring instruments
and, through training and experience:
·
understands what is required by the WHS
Regulations for noise
·
knows how to check the performance of the
instruments
·
knows how to take the measurements properly
·
can interpret the results of the noise measurements.
4.3 How
should a noise assessment be done?
The way a noise assessment is done will
depend upon:
·
the type of workplace
·
the number of persons potentially at risk from
exposure to hazardous noise
·
the information already available on noise at
the workplace.
A
noise assessment should be done during a typical working shift and should determine:
·
the noise levels produced during various tasks carried
out during the shift
·
how long your workers are exposed to noise
during each of these tasks.
An
assessment should take into account:
·
plant, equipment and other sources of noise in
operation at the workplace
·
how work activities are carried out
·
the length of the shift
·
environmental factors (e.g. types of walls,
surfaces, layout of work stations).
This
means that adequate information about the tasks and their frequency is needed,
so consultation with workers and their supervisors is essential.
Noise
measurements should be taken at 0.1 to 0.2 metres from the worker’s ear canal
entrance over a period of time that is representative of the noise produced
during the tasks.
In
most situations the use of a hand-held integrating sound level meter will produce
the most useful information for choosing appropriate noise control measures. In
situations where workers are highly mobile or access for the person taking the
measurement is difficult or unsafe, it may be more appropriate to use personal
sound exposure meters (dose meters).
Noise measurements should include the combined
noise levels of all the tools, machines and processes present as well as the
background noise from ventilation systems, cooling compressors, circulation
pumps, etc. To identify which noise sources contribute most to workers’
exposures, the noise from each source or work activity should also be measured
separately.
The Ready Reckoner in Appendix C may be used to work out the total LAeq,8h for combinations of noise levels and exposure duration for each work
activity and the relative importance of each.
If
a group of workers is exposed to identical sources of noise and their exposure
is likely to be the same, then you do not need a separate assessment for each
worker. A representative assessment can be done for one or more of the workers.
Extended
work shifts
Shift
durations of 10 hours or longer involve a degree of risk greater than that
indicated by the 8 hour measurement LAeq,8h. This increase in risk
arises because of the additional damaging effect of continuous exposure to
noise after 10 hours. The risk may be further increased if there is reduced recovery
time between successive shifts.
If
workers work shifts of 10 hours or more, the adjustment factor for extended
shifts as set out in AS/NZS 1269.1 (see Table 3) should be added to the
measured LAeq,8h before
comparing it with the 85 dB(A) exposure standard for noise.
Table
3: Adjustments to LAeq,8h for extended work shifts
Shift
length
|
Adjustment
added to measured
LAeq,8h dB(A) |
10 hrs or more to
less than 14 hrs
|
+ 1
|
14 hrs or more to
less than 20 hrs
|
+ 2
|
20 hrs or more
|
+ 3
|
For example, if a worker works 12-hour
shifts and the typical LAeq,8h has been determined to
be 93 dB(A), an additional one decibel
is added to give an adjusted LAeq,8h of 94 dB(A). Hence the worker‘s LAeq,8h exceeds the
exposure standard for noise by 9 dB(A). For a fully worked example see Appendix
C.
If
workers work more than five days per week, the weekly averaging procedure of
AS/NZS 1269.1 should be used.
4.4 What
information should be included in a noise assessment report?
Noise assessment reports should show that
the assessment was done properly and that all factors were taken into account. An
assessment report should contain all the information shown in Appendix D. Noise
assessment reports should be used to select appropriate control measures. The main
findings should be included in training for all workers. The reports should be
made available to managers, health and safety representatives and regulators.
The
most important step in the risk management process involves eliminating the
risks, or if that is not reasonably practicable, minimising the risks so far as
is reasonably practicable.
5.1 The
hierarchy of risk control
The
WHS Regulations require duty holders to work through a hierarchy of control to choose the control measure that
most effectively eliminates or minimises the risk in the circumstances. The
hierarchy ranks the ways of controlling the risk
of hearing loss from noise from the highest level of protection and
reliability to the lowest so that the most effective controls are considered
first.
Effective risk control
may involve a single control measure or a combination of two or more different
controls.
Eliminate the risk
The
most effective control measure is to eliminate the source of noise completely,
for example by ceasing to use a noisy machine, changing the way work is carried
out so hazardous noise is not produced or by not introducing the hazard into the
workplace.
If
it is not reasonably practicable to eliminate the source of noise, you must minimise
the risk associated with hearing loss so far as is reasonably practicable. This
includes ensuring that the noise does not exceed the exposure standard by
choosing one or more of the following measures:
·
substitute the hazard with plant or processes
that are quieter
·
modify plant and processes to reduce the noise
using engineering controls
·
isolate the source of noise from people by
using distance, barriers, enclosures and sound-absorbing surfaces.
If there is a remaining risk, it must be minimised so far as is
reasonably practicable by implementing administrative controls, and if a risk
still remains, then suitable personal protective equipment must be provided and
used. These
two types of control measures, when used on their own, tend to be least
effective in minimising risks because they rely on human behaviour and
supervision.
5.2 Substituting plant or processes to reduce noise
Buy ‘quiet’
One of the most cost-effective and long-term ways
of reducing noise at work is to introduce a purchasing and hiring policy to
choose the quietest plant for the job. This can be done by obtaining information
on noise emission (for example, data on sound power level or sound pressure
level at the operator position) from the manufacturer, importer or supplier of
plant and comparing it to determine the quietest plant.
Ask the suppliers about the likely noise emission
under the particular conditions in which you will operate the machinery, as
well as under standard test conditions. If you ask the same question to all
suppliers you can compare information. Sound power level data will only ever be
a guide as many factors affect the actual noise levels experienced by your
workers, but it will help you buy quieter machines.
You should purchase or hire only from suppliers who
can demonstrate a low noise design, with noise control as a standard part of
the machine, not as an optional extra.
Change the
way you do the job
A different way of doing the job may provide the
same result with a lot less noise. For example, bending metal in a vice or a
press is quieter than hammering it into shape, welding is generally quieter than
riveting, gluing is quieter than hammering in nails, clipping is quieter than
stapling, and lowering materials in a controlled manner is quieter than dropping
them on hard surfaces.
5.3 Using engineering controls
A good understanding of the operation of the plant
or process is necessary when considering ways of minimising noise at its
source.
Examples of engineering control measures include:
·
eliminating impacts between hard objects or
surfaces
·
minimising the drop height of objects or the
angle that they fall onto hard surfaces
·
using absorbent lining on surfaces to cushion
the fall or impact of objects
·
fitting exhaust mufflers on internal combustion
engines
·
fitting silencers to compressed air exhausts
and blowing nozzles
·
isolating a vibrating noise source to separate
it from the surface on which it is mounted using rubber mounts and flexible
connections
·
ensuring gears mesh together better
·
fixing damping materials (such as rubber) or
stiffening to panels to reduce vibration
·
fitting sound-absorbing materials to hard
reflective surfaces
·
turning down volume controls
·
changing fan speeds or the speeds of particular
components
·
changing the material the equipment or its
parts are made of (change metal components to plastic components).
Further information on
using engineering controls is at Appendix E.
5.4 Isolating the source of noise
Examples
of isolating the source of noise from workers include:
·
building enclosures or sound proof covers
around noise sources
·
using barriers or screens to block the direct
path of sound
·
locating noise sources further away from
workers (see Figure 1)
·
using remote controls to operate noisy plant
from a distance.
Figure 1: Sound spreading
in an open space away from reflecting surfaces and measured at a certain
distance from the source is reduced by about 6 dB for each doubling of that
distance. Sound is reduced less when spreading inside an enclosed space.
Regular maintenance
of plant and equipment is essential as it will deteriorate with age and can
become noisier. Check for changes in noise levels – badly worn bearings and
gears, poor lubrication, blunt blades, loose parts, unbalanced rotating parts
and steam or air leaks all create noise that can be reduced with good
maintenance. Engineering controls such as vibration
mountings, impact absorbers, gaskets, seals, silencers, barriers and other
equipment should be regularly inspected and maintained.
5.5 Using administrative
controls
Administrative
noise control measures reduce the amount of noise to which a person is exposed by
reducing the time they are exposed to it. Examples include:
·
organising schedules so that noisy work is done
when only a few workers are present
·
notifying workers and others in advance of noisy
work so they can limit their exposure to it
·
keeping workers out of noisy areas if their work
does not require them to be there
·
sign-posting noisy areas and restricting access
·
providing quiet areas for rest breaks for
workers exposed to noisy work
·
limiting the time workers spend in noisy areas
by moving them to quiet work before their daily noise exposure levels exceed
the exposure standard.
If you rely
on administrative controls, you should conduct regular checks to ensure that
they are being complied with.
5.6 Using personal hearing
protectors
Regulation 44: If personal protective equipment (PPE) is to be used at the workplace,
the person conducting the business or undertaking must ensure that the
equipment is:
- selected to
minimise risk to health and safety
- suitable for
the nature of the work and any hazard associated with the work
- a suitable size
and fit and reasonably comfortable for the person wearing it
- maintained,
repaired or replaced so it continues to minimise the risk
- used or worn by
the worker, so far as is reasonably practicable.
Regulation 46: A worker must, so
far as reasonably able, wear the PPE in accordance with any information,
training or reasonable instruction.
Personal hearing protectors, such as ear-muffs
or ear-plugs, should be used in the following circumstances:
·
when the risks arising from exposure to noise
cannot be eliminated or minimised by other more effective control measures,
·
as an interim measure until other control
measures are implemented
·
where extra protection is needed above what has
been achieved using other noise control measures.
If the use of personal hearing protectors is
necessary, it is important that the hearing protectors are worn throughout the
period of exposure to noise. Removing personal hearing protectors for even
short periods significantly reduces the effective attenuation (noise reduction) and might provide inadequate protection. For
example, a worker wearing a hearing protector for a full 8-hour day will receive
the 30 dB maximum protection level. However, one hour without wearing the
hearing protector causes the maximum protection level to fall to 9 dB.
Areas where people may be exposed to hazardous
noise should be sign-posted as hearing protector areas
and the boundaries of these areas should be clearly defined. Workers and other
persons, including managers and visitors, should not enter these areas without
wearing appropriate personal hearing protectors, regardless of how short the
time they stay in the hearing protector area.
Where sign-posting is not practicable, you
should make other arrangements to ensure that workers and others know when personal
hearing protectors are required. For example:
·
attach prominent
warning notices to tools and equipment indicating that personal hearing
protectors should be worn when operating them
·
provide written and
verbal instructions on how to recognise circumstances in which personal hearing
protectors are needed
·
ensure effective
supervision of identified hazardous tasks.
Personal hearing protectors should be selected
and maintained in accordance with AS/NZS 1269.3 Occupational noise
management – hearing protector program. Involve your workers in the
selection process and offer a reasonable choice from a range of types.
Suppliers of hearing protectors should provide
the full information on the attenuation likely to be provided including the
SLC80 ratings, class and octave band attenuation values. The attenuation values
should be derived from attenuation measurements made in accordance with AS/NZS
1270 Acoustics – hearing protectors.
Selection
When selecting personal hearing protectors you
should consider:
·
the degree of
attenuation required in the worker’s environment (see Table 4). Do not provide
protectors that overprotect by cutting out too much sound – this can cause difficulties
hearing verbal instructions and other sounds needed to work safely
·
the suitability for
the type of working environment and the work tasks. For example, ear-plugs are
difficult to use hygienically for work that requires them to be inserted with
dirty hands and in these circumstances, ear-muffs are more appropriate, but ear-muffs
can be uncomfortable to wear in hot environments and can make it difficult for
the wearer to enter a confined space or to wear a helmet
·
the comfort, weight
and clamping force of the personal hearing protector.
Table 4: Recommended Class of hearing
protector
|
|
Measured exposure
LAeq,8h dB(A)
|
Class
|
Less than
90
|
1
|
90 to less
than 95
|
2
|
95 to less
than 100
|
3
|
100 to
less than 105
|
4
|
105 to
less than 110
|
5
|
Individual fit of personal hearing protectors is critical for optimum
protection. Several devices are available to assist with this. Wearing work
equipment—such as hard hats, dust masks and eye protection—may affect the
performance of the protector. The fit of hearing protectors should be checked
while the user is wearing regular work equipment. Workers wearing spectacles
should be fitted with hearing protectors while wearing the spectacles.
Maintenance
Personal hearing protectors must be regularly
inspected and maintained to ensure they remain in good, clean condition. The
inspections should check that:
·
ear-muff seals are
undamaged
·
the tension of
headbands is not reduced
·
there are no
unofficial modifications
·
compressible ear-plugs
are soft, pliable and clean.
If disposable ear-plugs are used, they should
only be worn once.
You must provide your workers with training,
information and instruction in the proper use, fit, care and maintenance of
personal hearing protectors. You should also:
·
include the need to
wear hearing protectors in your safety procedures
·
place someone in
charge of issuing and making sure replacements are readily available
·
carry out spot checks
to ensure that workers are wearing their hearing protectors when required and
are using them correctly
·
ensure all managers
and supervisors set a good example and wear personal hearing protectors at all
times when in hearing protector areas.
5.7 Audiometric testing
Regulation 58: A person conducting a business or undertaking must provide audiometric
testing for a worker who is carrying out work for the business or undertaking if
the worker is required to frequently use personal hearing protectors as a
control measure for noise that exceeds the exposure standard.
Audiometric testing must be provided within
three months of the worker commencing work. Starting the audiometric testing before people are exposed to
hazardous noise (such as new starters or those changing jobs) provides a
baseline as a reference for future audiometric test results. Regular follow-up
tests must be carried out at least every two years. These should be undertaken
well into the work shift so that any temporary hearing loss can be picked up.
More frequent
audiometric testing (e.g. every six months) may be needed if exposures are at a
high LAeq,8h, which is equal or
greater than 100 dB(A).
Before introducing an audiometric testing
program, you must consult with your workers and their health and safety
representatives. It is important that your workers understand that the aim of
the testing is to evaluate the effectiveness of control measures to protect
their hearing.
Audiometric testing and
assessment of audiograms should be carried out by competent persons in
accordance with the procedures in AS/NZS 1269.4:2005 - Occupational noise management - Auditory assessment.
Workers should be given the results of
audiometric testing accompanied by a written explanation of the meaning and
implications. Only with the consent of the worker should you provide their
results to other parties. Unidentifiable individual results and group data should
be made available to health and safety representatives of the worker’s work
group.
The reasons for any changes in hearing levels
over time should be thoroughly investigated.
When temporary or
permanent threshold shifts are revealed through audiometric assessments or a
worker reports a recent diagnosis of tinnitus, you must review your control
measures to determine whether more effective control measures can be
implemented so that your workers do not have to rely on personal hearing
protectors.
If the worker is to
continue using personal hearing protectors, you should:
·
verify that the nominal performance of the
worker’s personal hearing protector is adequate for the level of exposure to
noise
·
examine the protector carefully and ensure it
is not damaged
·
check the protector fits the worker closely
with no leakage paths for noise
·
ask the worker if they have any difficulty
using the protector
·
check the worker uses the protector correctly
and consistently whilst performing their work.
If workers are found to have sufficient
hearing loss to interfere with the safe performance of their work,
all reasonably practicable steps should be taken to modify the work
environment. This may include providing:
·
volume control on equipment such as telephones
·
acoustically treated meeting areas with low
noise and low sound reflections
·
supplementary visual warning signals
·
alternative work for the worker if other
measures do not remedy the situation.
Monitoring hearing with regular audiometric
testing is recommended in situations where workers are exposed to:
·
any of the ototoxic substances listed in Appendix
A where the airborne exposure (without regard to respiratory protection worn)
is greater than 50 per cent of the national exposure standard for the
substance, regardless of the noise level
·
ototoxic substances at any level and noise with
LAeq,8h greater than 80 dB(A) or LC,peak greater
than 135 dB(C)
·
hand-arm vibration at any level and noise with LAeq,8h greater
than 80 dB(A) or LC,peak greater than 135 dB(C).
5.8 Information, training and instruction
Section 19: A person conducting a business or undertaking
must ensure, so far as is reasonably practicable, that information, training
and instruction is provided to workers and others at the workplace to protect them
from health and safety risks.
Regulation 39: The information, training and instruction must, so far as is
reasonably practicable, be provided in a way that can be easily understood by
any person to whom it is provided.
Training should be provided to:
·
those workers who may be exposed to hazardous
noise or other agents that may contribute to hearing loss
·
their managers and supervisors
·
workplace health and safety committees and
health and safety representatives
·
those responsible for the purchase of plant,
noise control equipment, personal hearing protectors and for the design,
scheduling, organisation and layout of work.
The contents of the training program should
include:
·
the health and safety responsibilities of each
party at the workplace
·
how hearing can be affected by exposure to
noise
·
the detrimental effects hearing loss and
tinnitus have on the quality of life, both at work and socially
·
the tasks at the workplace that have the
potential to give rise to hearing loss and the likely noise exposure level
·
how to use noise control measures
·
how to select, fit, wear, maintain and store
personal hearing protectors
·
how to report defects in hearing protectors and
noise control equipment or raise any concerns regarding hazardous noise
·
the purpose and nature of audiometric testing.
5.9 Implementing and
maintaining control measures
A noise management plan may help implement the
chosen noise control measures effectively. It should identify what action needs
to be taken, who will be responsible for taking the action and by when.
The plan should be based on the results of any
noise assessment and should also include:
·
measuring noise levels
to confirm that control measures are achieving expected attenuation
·
specifications for
purchasing or hiring plant
·
a description of any
training and supervision that may be needed
·
control measures for
temporary work areas and situations
·
timeframes for
reviewing noise assessments and control measures.
Regulation 37: You must ensure that the control measures you
implement remain effective. This includes checking that the control measures
are suitable for the nature and duration of the work, are installed, maintained
and used correctly.
Any noise control
measures that are implemented must be reviewed, and if necessary revised, to
make sure they work as planned and to maintain, so far as is reasonably
practicable, a work environment that is without risks to health and safety.
Regulation 38: A person conducting a business or undertaking
must review and as necessary revise noise control measures:
·
when the control measure does not control the
risk so far as is reasonably practicable
·
before a change at the workplace that is likely
to give rise to a new or different health and safety risk that the control
measure may not effectively control
·
if a new hazard or risk is identified
·
if the results of consultation indicate that a
review is necessary
·
if a health and safety representative requests
a review.
Control measures may be reviewed using the same
methods as the initial hazard identification step.
Consult your workers and their health and
safety representatives and consider the following:
·
Are the control measures working effectively in
both their design and operation?
·
How accurate is the risk assessment process?
Are all noisy activities being identified?
·
Have new work methods or new plant made the work
quieter?
·
Has instruction and training provided to
workers been successful?
·
Have new requirements or information indicated that
current controls are no longer the most effective?
·
Is an alteration planned to any structure,
plant or process that is likely to result in a worker being exposed to hazardous
noise?
·
Has an incident occurred as a result of a
worker being exposed to hazardous noise?
·
Have any audiometric tests revealed changes in
hearing threshold levels?
You should decide on the time
interval between noise assessments by consulting with your workers. Assessment should
be repeated whenever there is:
·
installation or removal of machinery or other noise
sources likely to cause a significant change in noise levels
·
a change in workload or equipment operating conditions
likely to cause a significant change in noise levels or exposure times
·
a change in building structure likely to affect noise
levels
·
a change to working arrangements affecting the length
of time workers spend in noisy work areas.
If you design, manufacture or supply products
used for work you should check that the product effectively eliminates or minimises
exposure to noise by obtaining feedback from users. This can help in determining
whether any improvements can be made.
Eliminating noise in the early stages
of product planning (at the source) is more effective and usually cheaper than
making changes after noise hazards are introduced into the workplace.
7.1 Designers
Designers
of plant or structures used for work must ensure so far as is reasonably
practicable that the plant or structure is designed to be without risks to the
health and safety of persons.
Regulation 59: A designer of plant must design the plant so that its noise
emission is as low as reasonably practicable.
Designers must provide information on
the noise emission values of the plant (for example, data on sound power level or sound pressure level), the operating conditions of the plant
when the noise emission is measured and the methods used to measure the noise
emission. They must also provide information on any conditions required for
safe use.
This information must be provided to
manufacturers, importers and suppliers.
If you design plant you should consider:
·
preventing or reducing the impact between
machine parts
·
replacing metal parts with quieter plastic
parts
·
combining machine guards with acoustic
treatment
·
enclosing particularly noisy machine parts
·
selecting power transmission which permits the
quietest speed regulation; for example, rotation-speed-controlled electric
motors
·
isolating vibration-related noise sources within
machines.
You should also design:
·
good seals for doors for machines
·
machines with effective cooling flanges that
reduce the need for air jet cooling
·
quieter types of fans or placing mufflers in
the ducts of ventilation systems
·
quiet electric motors and transmissions
·
pipelines for low flow speeds (maximum 5m/sec.)
·
ventilation ducts with fan inlet mufflers and
other mufflers to prevent noise transfer in the duct between noisy and quiet
rooms.
Methods of maintenance and servicing should be
taken into account in noise control design.
Designers of buildings and structures must
take noise control into account from the beginning of the planning process and
minimise the noise transmitted through the structure to the lowest level that
is reasonably practicable.[2]
For new buildings designers should consider:
·
the effect on noise levels of building
reverberation, the building layout and location of workstations relative to any
plant
·
selecting the frame, floor and machine bases so
that all sources of disturbance can be provided with effective vibration
isolation. Heavy, noisy equipment requires rigid, heavy bases. It is also
possible to isolate machine bases from direct contact with the rest of the
building frame (see Figure 2)
·
isolating noise sources such as plant rooms
·
designing acoustic treatments for noisy areas,
for example, cover ceilings (and walls in the case of very high ceilings) with
sound-absorbing material, use floating floors
·
using flexible construction joints as building
elements
·
designing walls, floors, windows and doors to
provide the necessary sound transmission loss
·
covering floors of office areas with carpets.
Figure 2: The vibrations of an elevator drive are isolated from the building
structure.
With automation of processes,
remote control from a separate room may be possible. Some control measures may
include:
·
designing control rooms with materials having
adequate transmission loss
·
providing good sealing around doors and windows
·
providing openings for ventilation with
passages for cables and piping equipped with good seals.
Control rooms should be adequately
ventilated with air-conditioning in hot working areas. Otherwise, there is a
risk that the doors will be opened for ventilation, which would spoil the
effectiveness of the room in reducing the noise level.
Figure 3: Examples of noise control measures in an industrial building
7.2 Manufacturers
Regulation 59: A manufacturer of plant must manufacture the plant so that
its noise emission is as low as reasonably practicable.
Manufacturers
of plant or structures used for work must ensure, so far as is reasonably
practicable, that the plant or structure is manufactured without risks to the
health and safety of persons. If noise cannot be eliminated, manufacturers must
ensure the plant is manufactured so that its noise emission is as low as
reasonably practicable and that the manufacturing process does not introduce
new or additional noise hazards.
Manufacturers
should manufacture plant:
·
using and testing the safety measures specified by the
designer
·
using materials and techniques that minimise the risk of
hearing loss by reducing noise to the lowest level reasonably practicable.
Manufacturers
must provide information to an importer or supplier on the noise emission
values of the plant, the operating conditions of the plant when the noise
emission is measured and the methods used to measure the noise emission. They
must also provide information on any conditions required for safe use.
7.3 Suppliers and importers
Suppliers
or importers must ensure so far as is reasonably practicable that the plant is
without risks to the health and safety of persons at the time of supply.
Suppliers
and importers must take all reasonable steps to obtain the information that the
manufacturer is required to provide on noise emission values and provide it to
any person to whom the plant is supplied.
Suppliers
and importers should:
·
provide all noise control measures with the product as per
the setup recorded on the noise test results
·
provide maintenance information to ensure safe use and
operation.
7.4 Installers
Installers
must ensure so far as is reasonably practicable that the plant or structure is
installed in such a way that it is without risks to the health and safety of
persons. For example, installers should ensure that the installation is
undertaken according to the designer’s specifications. Isolating vibrating
sources of noise may involve installing large heavy machines on separate bases
or in such a way that they do not directly contact the remainder of the
building structure.
Installers
should also provide information to potential users about the conditions
required for safe use, including maintenance requirements.
7.5 What information should
be provided to potential users?
Designers,
manufacturers, suppliers and importers must give purchasers and other potential
users the information they need to safely use the plant, including the results
of any calculations, analysis or testing carried out.
Information must include the noise
emission values of the plant, the operating conditions of the plant when the
noise emission is measured and the methods used to measure the noise emission.
This information will help purchasers choose plant
with low noise levels.
Where there is a selection of noise
measurement results available, the preferred measurement is the sound pressure
level at the operator's position.
Instructions for safe use should be
communicated in a way that can be easily understood by users.
Supplier's details
|
For example, name, local address, telephone and/or
facsimile number , email
|
Manufacturer's details
|
For example, name, address, telephone and/or facsimile
number ,email
|
Details of the plant tested
|
Including any noise controls, for example, make, model,
serial number, relevant capacity/rating
|
Title or number of specific test standard or code followed
|
Including details of any departures from the standard. For
example, if a machine needed to be mounted differently to the method given in
the standard, the alternative mounting should be described
|
Details of operating conditions
|
If not specified in the standard, or if no specific test
standard is available for the type of plant being tested. For example, test
machine load, speed, type of material processed, details of installation and
mounting of test machine, details of test environment, description of
measurement instrumentation and procedure. Reference to a test report
containing this information will suffice
|
Measurement position(s)
|
For example, operator’s ear or 1 metre from machines
|
Index measured
|
For example, sound pressure level or sound power level
|
Frequency weighting
|
For example, A, C or linear
|
Time weighting
|
For example, slow, fast or peak, or Leq
|
Sound level or levels determined in testing.
|
|
Units of measurement
|
For example, dB re: 20 micropascals
|
Details of tester
|
For example, name, address, telephone and/or facsimile
number ,email, accreditation
|
Date issued
|
|
Vibration
Studies have indicated that there is a link
between exposure to hand-arm vibration and hearing loss. Workers who use
equipment such as chainsaws that subject the worker to both hand-arm vibrations
and to noise may be more likely to suffer from hearing loss. Tools that may
expose workers to both noise and hand-arm vibration include:
·
pneumatic and electrical rotary tools such as
concrete breakers, grinders, sanders and drills
·
percussive tools such as chippers and riveters
·
petrol-powered tools such as lawn-mowers,
brush-cutters and chainsaws.
Control measures to reduce exposure to hand-arm
vibration may involve finding alternative ways to do the work that eliminates
the need to use vibrating equipment or to purchase tools that produce less
vibration.
Ototoxic substances
Exposure to some chemicals can result in
hearing loss. These chemicals are known as ototoxic substances. Hearing loss is
more likely to occur if a worker is exposed to both noise and ototoxic
substances than if exposure is just to noise or ototoxic substances alone.
There are three major classes of ototoxic
substances: solvents, heavy metals and asphyxiants. Work activities that
commonly combine noise and ototoxic substances include:
·
painting
·
printing
·
boat building
·
construction
·
furniture making
·
fuelling vehicles and aircraft
|
·
manufacturing, particularly of metal, leather
and petroleum products
·
degreasing
·
fire-fighting
·
weapons firing
|
Some medications have also been identified as ototoxic
substances. These include some anti-cancer, anti-inflammatory, anti-thrombotic,
anti-malarial, anti-rheumatic and antibiotic drugs. Quinine and salicylic acids
(such as aspirin) are also considered to be ototoxic substances.
Table A1 below lists those ototoxic substances
most commonly used in workplaces. Some of these can be absorbed through the
skin and are considered particularly hazardous.
Exposure standards for chemicals and noise have
not yet been altered to take account of increased risk to hearing. Until
revised standards are established, it is recommended that the daily noise
exposure of workers exposed to any of the substances listed in Table A1 be
reduced to 80 dB(A) or below. They should also undergo audiometric testing and
be given information on ototoxic substances.
Control measures such as substitution,
isolation and local ventilation should be implemented to eliminate or reduce
chemical exposures. Personal protective equipment should be used to prevent
skin and respiratory absorption when other controls are insufficient.
Acoustic incidents are sudden, unexpected loud
noises occurring during telephone headset use, including crackles, hisses,
whistles, shrieks or high-pitched noises. Acoustic
shock is not caused by the loudness of a telephone, as all phone noise is
electronically limited to a peak noise level of 123 decibels, but by a sudden
rise in noise levels.Acoustic Shock
The noises can come from a wide variety of
sources, either within the transmission system or from the customer end.
Sources of acoustic incidents include those outlined in Table A2:
Table A2:
Sources of acoustic incidents
|
|
Sources
within the transmission system
|
Sources
from the customer end
|
§ faulty or
damaged networks, telephones and headset equipment
§ broadband
and narrowband interference
§ mobile
phones or fax machines used in call centres
|
§ feedback
oscillation from some cordless phones
§ alarm
signals
§ phone
receivers slammed down or dropped
§ tones from
misdirected facsimiles and modems
§ noises
made close to the receiver (eg. whistling)
|
Although acoustic incidents occur in workplaces
(mainly call centres), only a very small proportion cause the symptoms known as
‘acoustic shock’ in workers.
High background noise levels at the workplace
can increase the risk of acoustic shock occurring from an acoustic incident.
For example, operators may raise the volume in their headsets to improve
hearing thereby increasing the impact of any sudden, loud telephone noise. When
an acoustic incident occurs, the operator’s automatic reaction may be to remove
the headset or receiver as quickly as possible and, in some cases, this may
help prevent or reduce the effects of acoustic shock.
Other factors, such as a middle
ear inflammation and feelings of tension, may increase the likelihood of an
acoustic shock resulting from an acoustic incident.
Acoustic shock symptoms
The effect on individuals can
vary greatly for the same increase in sound level. Only a small number of
people develop symptoms from an acoustic incident. Why a person experiences
symptoms after an acoustic incident is not known with certainty and is still
being researched.
Some researchers believe that a combination
of stress and sudden loud noise causes excessive contraction of the middle ear
muscles, triggering the acoustic shock symptoms.
Audiologists have grouped
symptoms into three categories:
·
Primary (immediate) symptoms, which
include but are not limited to:
o
a feeling of fullness in the ear
o
burning sensations or sharp pain around or in
the ear
o
numbness, tingling or soreness down the side of
face, neck or shoulder
o
nausea or vomiting
o
dizziness
o
tinnitus and other head noises such as eardrum
fluttering.
·
Secondary symptoms, which include but are
not limited to:
o
headaches
o
fatigue
o
a feeling of being off-balance
o
anxiety
·
Tertiary symptoms, which include but are
not limited to:
o
hypersensitivity (sensitivity to previously
tolerated sounds such as loud voices, television and radio)
o
hyper vigilance i.e. being overly alert.
People experiencing such symptoms
will respond in different ways. As with other workplace injuries and ill
health, some may experience further effects, including anger, anxiety, social
isolation and other psychological problems.
Few people suffer hearing loss
from acoustic shock. To assist in the diagnosis where this may occur,
consideration should be given to baseline audiometric testing of all operators’
hearing by a specialist when they commence work to establish their baseline
hearing ability.
Control measures
Control measures to eliminate or
minimise the risk of acoustic shock include:
·
providing high quality headsets with acoustic
shock protection devices
·
giving prompt attention to damaged equipment
and network faults – the equipment or network supplier or an acoustic
specialist should be contacted if necessary
·
ensuring the proper fitting, use and
maintenance of headsets
·
reducing background noise in the room
·
providing information and training on how to
detect warning sounds for example, cordless phones being used too close to the
base station at the customer end. Training on warning sounds should also
prepare operators to know when to remove headsets as quickly as possible, where
necessary
·
with hotdesking work, ensuring workers turn the
headset volume down as soon as possible after a changeover
·
considering work organisation issues, such as
unreasonable or unrealistic performance pressures or demands, which may cause
tension and distress
·
preventing mobile phones from being used in
call centres.
Control of background noise in call centres
Possible control measures to implement include:
·
reviewing the design and layout of the room and
workstations:
o reducing external and building service noise
o reducing reverberation within the room by using sound absorbing
materials
o placing acoustic barriers around/between workstations and other call
centre areas
·
encouraging people to not talk loudly or hold discussions
near operators
·
locating fax machines, photocopiers and
printers away from operators
·
controlling radio noise and use of mobile
telephones
·
with hotdesking, ensuring changeovers are
smoothly managed and quiet
·
providing sufficient room for workers to move
around at changeover times without
crowding.
Managing acoustic incidents
After an acoustic incident, the
worker should:
·
remove the headset immediately
·
in some circumstances, move to the ‘break out’
area
·
report the incident and any symptoms to the supervisor
·
discuss with the supervisor their ability to
continue work and, where appropriate, relocate to another workstation.
After an acoustic incident, you should:
·
ensure the event is recorded and logged
·
discuss the incident and ability to continue
work with the worker
·
where symptoms are persistent or severe, refer
the worker to a general practitioner and/or an audiologist for assessment and
treatment of possible injury
·
enquire into the cause of the noise, including
whether it is from an internal or external source
·
ensure the headset and other equipment is
checked for clarity of sound and possible damage and faults
·
remove damaged or faulty equipment from service
·
review the adequacy of the noise control
measures and general working environment.
Description of work
location:_________________________________________________
Activities at
workstation:________________________________________________________
Assessed
by:______________________________________________________________
Date:____________________________________________________________________
‘Yes’ to any of the following indicates the need to carry
out a noise assessment if exposure to the noise cannot be immediately
controlled.
Tables C1 to
C3 provide a simple way of working out a worker’s LAeq,8h (eight-hour
equivalent continuous sound pressure level) if you know the noise level and
duration of each of the noisy tasks carried out by the worker during the work
shift.[4]
From Tables C1 or C2 you read off
the number of “noise exposure points” that correspond to a particular task’s
noise level and exposure duration. Table C1 is for noise levels between 75 and
105 dB(A) and Table C2 is for higher noise levels between 95 and 125 dB(A).
For example, a task producing a
noise level at the worker’s ear of 93 dB(A) that is done for two lots of 30
minutes in a shift (i.e. one hour total) produces 80 noise exposure points.
Another task with a noise level of 120 dB(A) for one minute during the shift
produces 670 points.
These points can be added (in the
normal arithmetic way) to give the total exposure points for the shift. Table
C3 is then used to convert the total points to the LAeq,8h.
In the example above, if these were
the only noisy tasks carried out by the worker, the points total is 750 and
(from Table C3, rounding to the nearest whole decibel) the LAeq,8h
for the worker is 94 dB(A).
This calculated LAeq,8h
value can be compared with the exposure standard for noise i.e. LAeq,8h
= 85 dB(A). Additionally, noise exposure points can be used to prioritise the
noise control program by showing which tasks make the greatest contribution to
the total noise exposure.
In the example above the worker’s LAeq,8h
is greater than the standard, so noise control action is needed. Although it
only lasts for one minute, the 120 dB(A) task contributes more than eight times
as much as the other task to the total exposure and so should be the first one
tackled.
In this scheme the exposure
standard for noise – LAeq,8h
= 85 dB(A) – is 100 points.
Table C1: Exposure points
for 75-105 dB(A)/15minutes – 12 hours
Sound
Level
LAeq,T dB(A)
|
Duration
of exposure per shift
|
|||||||
15 min
|
30 min
|
1 h
|
2 h
|
4 h
|
8 h
|
10 h*
|
12 h*
|
|
105
|
320
|
640
|
1270
|
2530
|
5060
|
10120
|
12650
|
15180
|
104
|
250
|
500
|
1000
|
2010
|
4020
|
8040
|
10050
|
12060
|
103
|
200
|
400
|
800
|
1600
|
3200
|
6400
|
8000
|
9600
|
102
|
160
|
320
|
640
|
1270
|
2540
|
5070
|
6340
|
7600
|
101
|
130
|
250
|
500
|
1010
|
2010
|
4030
|
5040
|
6040
|
100
|
100
|
200
|
400
|
800
|
1600
|
3200
|
4000
|
4800
|
99
|
80
|
160
|
320
|
640
|
1270
|
2540
|
3180
|
3810
|
98
|
63
|
130
|
250
|
500
|
1010
|
2020
|
2520
|
3030
|
97
|
50
|
100
|
200
|
400
|
800
|
1600
|
2000
|
2410
|
96
|
40
|
80
|
160
|
320
|
640
|
1270
|
1590
|
1910
|
95
|
32
|
63
|
130
|
250
|
510
|
1010
|
1260
|
1520
|
94
|
25
|
50
|
100
|
200
|
400
|
800
|
1000
|
1210
|
93
|
20
|
40
|
80
|
160
|
320
|
640
|
800
|
960
|
92
|
16
|
32
|
63
|
130
|
250
|
510
|
630
|
760
|
91
|
13
|
25
|
50
|
100
|
200
|
400
|
500
|
600
|
90
|
10
|
20
|
40
|
80
|
160
|
320
|
400
|
480
|
89
|
7.9
|
16
|
32
|
64
|
130
|
250
|
320
|
380
|
88
|
6.3
|
13
|
25
|
50
|
100
|
200
|
250
|
300
|
87
|
5.0
|
10
|
20
|
40
|
80
|
160
|
200
|
240
|
86
|
4.0
|
8.0
|
16
|
32
|
64
|
130
|
160
|
190
|
85
|
3.2
|
6.3
|
13
|
25
|
50
|
100
|
130
|
150
|
84
|
2.5
|
5.0
|
10
|
20
|
40
|
80
|
100
|
120
|
83
|
2.0
|
4.0
|
8.0
|
16
|
32
|
64
|
80
|
96
|
82
|
1.6
|
3.2
|
6.3
|
13
|
25
|
51
|
63
|
76
|
81
|
1.3
|
2.5
|
5.0
|
10
|
20
|
40
|
50
|
60
|
80
|
1.0
|
2.0
|
4.0
|
8.0
|
16
|
32
|
40
|
48
|
79
|
0.8
|
1.6
|
3.2
|
6.4
|
13
|
25
|
32
|
38
|
78
|
0.6
|
1.3
|
2.5
|
5.0
|
10
|
20
|
25
|
30
|
77
|
0.5
|
1.0
|
2.0
|
4.0
|
8.0
|
16
|
20
|
24
|
76
|
0.4
|
0.8
|
1.6
|
3.2
|
6.4
|
13
|
16
|
19
|
75
|
0.3
|
0.6
|
1.3
|
2.5
|
5.1
|
10
|
13
|
15
|
Table C2: Exposure points
for 95-125 dB(A)/5 seconds – 10 minutes
Sound
Level
LAeq,T dB(A)
|
Duration
of exposure per shift
|
|||||||
5 sec
|
10 sec
|
15 sec
|
30 sec
|
1 min
|
2 min
|
5 min
|
10 min
|
|
125
|
180
|
360
|
530
|
1050
|
2110
|
4220
|
10540
|
21080
|
124
|
140
|
280
|
420
|
840
|
1680
|
3350
|
8370
|
16750
|
123
|
110
|
220
|
330
|
670
|
1330
|
2660
|
6650
|
13300
|
122
|
90
|
180
|
260
|
530
|
1060
|
2110
|
5280
|
10570
|
121
|
70
|
140
|
210
|
420
|
840
|
1680
|
4200
|
8390
|
120
|
56
|
110
|
170
|
330
|
670
|
1330
|
3330
|
6670
|
119
|
44
|
88
|
130
|
270
|
530
|
1060
|
2650
|
5300
|
118
|
35
|
70
|
110
|
210
|
420
|
840
|
2100
|
4210
|
117
|
28
|
56
|
84
|
170
|
330
|
670
|
1670
|
3340
|
116
|
22
|
44
|
66
|
130
|
270
|
530
|
1330
|
2650
|
115
|
18
|
35
|
53
|
110
|
210
|
420
|
1050
|
2110
|
114
|
14
|
28
|
42
|
84
|
170
|
330
|
840
|
1680
|
113
|
11
|
22
|
33
|
67
|
130
|
270
|
670
|
1330
|
112
|
8.8
|
18
|
26
|
53
|
110
|
210
|
530
|
1060
|
111
|
7.0
|
14
|
21
|
42
|
84
|
170
|
420
|
840
|
110
|
5.6
|
11
|
17
|
33
|
67
|
130
|
330
|
670
|
109
|
4.4
|
8.8
|
13
|
26
|
53
|
110
|
270
|
530
|
108
|
3.5
|
7.0
|
11
|
21
|
42
|
84
|
210
|
420
|
107
|
2.8
|
5.6
|
8.4
|
17
|
33
|
67
|
170
|
330
|
106
|
2.2
|
4.4
|
6.6
|
13
|
27
|
53
|
130
|
270
|
105
|
1.8
|
3.5
|
5.3
|
11
|
21
|
42
|
110
|
210
|
104
|
1.4
|
2.8
|
4.2
|
8.4
|
17
|
33
|
84
|
170
|
103
|
1.1
|
2.2
|
3.3
|
6.7
|
13
|
27
|
67
|
130
|
102
|
0.9
|
1.8
|
2.6
|
5.3
|
11
|
21
|
53
|
110
|
101
|
0.7
|
1.4
|
2.1
|
4.2
|
8.4
|
17
|
42
|
84
|
100
|
0.6
|
1.1
|
1.7
|
3.3
|
6.7
|
13
|
33
|
67
|
99
|
0.5
|
0.9
|
1.3
|
2.7
|
5.3
|
11
|
27
|
53
|
98
|
0.4
|
0.7
|
1.1
|
2.1
|
4.2
|
8.4
|
21
|
42
|
97
|
0.3
|
0.6
|
0.8
|
1.7
|
3.3
|
6.7
|
17
|
33
|
96
|
0.2
|
0.5
|
0.7
|
1.3
|
2.7
|
5.3
|
13
|
27
|
95
|
0.2
|
0.4
|
0.5
|
1.1
|
2.1
|
4.2
|
11
|
21
|
Table C3: Conversion
|
|
Total exposure points
|
LAeq,8h
dB(A)
|
32000
|
110
|
25420
|
109
|
20190
|
108
|
16040
|
107
|
12740
|
106
|
10120
|
105
|
8040
|
104
|
6400
|
103
|
5070
|
102
|
4030
|
101
|
3200
|
100
|
2540
|
99
|
2020
|
98
|
1600
|
97
|
1270
|
96
|
1010
|
95
|
800
|
94
|
640
|
93
|
510
|
92
|
400
|
91
|
320
|
90
|
250
|
89
|
200
|
88
|
160
|
87
|
130
|
86
|
100
|
85
|
80
|
84
|
64
|
83
|
51
|
82
|
40
|
81
|
32
|
80
|
25
|
79
|
20
|
78
|
16
|
77
|
13
|
76
|
10
|
75
|
Notes:
1. If there is only one source of noise
exposure, a quick glance at the background colour of the table cell
corresponding to the sound level and duration of exposure will tell you if the
worker is:
(a) above the LAeq,8h 85 dB(A) exposure standard - Red
(b) well below the LAeq,8h 85 dB(A) standard - Green
(c) marginal (between LAeq,8h 80 and 85 dB(A)) – Yellow
2. For durations of exposure not listed in
the table, add together the points from two durations that together give the
same duration. For example, for five
hours at 95 dB(A), add together the points for four hours at 95 dB(A) and one hour at 95 dB(A), i.e. 510 + 130, giving
a total of 640 points.
3. The tables can be extended to include
both higher and lower sound levels. A
change of 10 dB(A) results in a tenfold change in the points. For example, one
hour exposure at 108 dB(A) will give 10 times the points for one hour at 98
dB(A), that is, 2500 points.
4.
For shift lengths of 10 hours or more (*), the adjustments
listed in Table 3 should be added to the LAeq,8h before comparing the result with the
exposure standard for noise.
Example:
Carpenter working a 10.5-hour shift using tools and machines listed
below.
Machine/Process
|
Measured Sound Level
LAeq,T dB(A)
|
Duration per shift
|
Circular Saw – cutting hardwood
|
94
|
2 h
|
Planer – planing hardwood
|
100
|
3 h
|
Power Drill – drilling hardwood
|
87
|
4 h
|
Hammering nails into wood
|
98
|
10 min
|
Background
|
70
|
1 h 20 min
|
If you want to just quickly see if the
carpenter is exposed above the LAeq,8h
= 85 dB(A) noise standard, look up points for 94 dB(A) and 2
h in Table C1. You will see that the
cell is red, so you know without going any further that the carpenter is
exposed to noise above the standard.
If you want to actually work out the
carpenter’s 8h-equivalent continuous noise level, LAeq,8h, then use Tables C1, C2 and C3 as
below:
Machine/Process
|
Sound Level
LAeq,T dB(A)
|
Duration per shift
|
Points
|
Circular Saw – cutting hardwood
|
94
|
2 h
|
200
|
Planer – planing hardwood
|
100
|
3 h
|
2 h 800
1 h 400
|
Power Drill – drilling hardwood
|
87
|
4 h
|
80
|
Hammering nails into wood
|
98
|
10 min
|
42
|
Background
|
70
|
1 h 20 min
|
1 h 0.4
20 m 0.1
|
Total 10.5
h
|
Total
1522.5
|
From Table C3: LAeq,8h = 97 dB(A), but as the shift is 10.5 hours, an adjustment of +1 dB(A) is
needed, hence the adjusted LAeq,8h = 98 dB(A).
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