Noise at Work Assessments Explained
Noise at Work Assessments Explained produced by ParkerJones Acoustics, acoustic consultants and noise experts.
The ‘Control of Noise at Work Regulations 2005’ (‘the NAW Regulations’) sets out the legal requirements in respect
of protecting employees against risks to their health and safety arising from
exposure to noise whilst at work. The
aim of the NAW Regulations is to protect workers from suffering long term
hearing damage and tinnitus as a result of prolonged exposure to high noise
levels in the workplace.
What are my duties as an Employer?
The NAW Regulations apply to all
workplaces and mean that employers are legally obliged to risk assess the
exposure of their employees' exposure to noise within the working
environment. The employer must employ
appropriate control measures to reduce noise exposure where necessary.
Regulation 5 of the NAW
Regulations states that a detailed Noise at Work Risk Assessment (the purpose
of this document) must be undertaken if an employee is likely to be exposed to
noise at or above lower exposure action values (see Section 2.2). This may occur if a
workplace is considered to be noisier than everyday life.
Noise Exposure Action Values/Limits
In accordance with Regulation 4
of the NAW Regulations, a set of noise exposure action values are set which
relate to the average levels of noise exposure over a working day or week, and
the peak sound pressure exposure to which employees are exposed to in a working
day. In summary:
·
‘exposure action values’ are
the levels of exposure to noise at which employees can be exposed to, but employers
are required to take certain actions to mitigate this risk, including the
provision of hearing protection; and
·
‘exposure limit values’ are the
levels of noise exposure at which an employee must not be exposed to,
after taking into account the noise reduction provided by personal hearing
protection.
As per Regulation 4, the
following exposure action and limit values are defined:
Table 1 – Definition of
the exposure action and limit values
Action
Level
|
Threshold
Values
|
Actions Required if Thresholds
Exceeded
|
Lower
Exposure Action
Value
(LEAV)
|
· a daily personal exposure level (LEP,d)1 of
80 dB(A).
· a peak sound pressure level (LCPeak)
of 135 dB(C).
(these limits do not account for hearing
protection)
|
In the first instance, the employer should explore
other methods of reducing noise levels to as low a level as is reasonably
practicable. If the LEAV is still exceeded, then hearing protection is recommended
and the employer must provide personal hearing protectors upon the request of
any employee in this exposure category (though it must not be
compulsory for the employee to wear them unless they are in a designated
Hearing Protection Zone (HPZ).
The employer must also provide ‘information,
instruction, and training’ to employees who are exposed to above the LEAV.
|
Upper Exposure
Action
Value
(UEAV)
|
· a daily personal exposure level (LEP,d)1 of
85 dB(A).
· a peak sound pressure level (LCPeak)
of 137 dB(C).
(these limits do not account for hearing
protection)
|
The employer shall reduce exposure to as low a level as
is reasonably practicable by establishing and implementing a programme of
organisational and technical measures, excluding the provision of personal
hearing protectors, which is appropriate to the activity (see following
subsections).
If the UEAV is still exceeded, then hearing protection
is compulsory to employees in this exposure category and must be
supplied by the employer. If a
particular area is above the UEAV, then this area must be designated as a HPZ. The employers must ensure that affected
employees or employees entering the HPZ use hearing protection, who also have
a duty to protect themselves.
|
Exposure Limit
Value (ELV)
|
· a daily personal exposure level (LEP,d)1 of
87 dB(A).
· a peak sound pressure level (LCPeak)
of 140 dB(C).
(the effect of personal hearing protection is
accounted for in these limits)
|
Employees
must not be permitted to be exposed above the exposure limits (after
accounting for the noise reduction provided by personal hearing
protection).
Action
must be taken immediately to reduce exposure if this limit has been
exceeded. The employer must review the
programme of control measures, considering the technical and organisational
controls, the adequacy of any hearing protection supplied and systems in
place that ensures noise-control measures and hearing protection are properly
used and maintained.
|
1 These limits can also apply to a weekly
personal exposure level (LEP,w)
2 It may be necessary to conduct ongoing
health surveillance for the exceedance of the LEAV and UEAV.
|
What
do these action values mean? How do I mitigate noise?
In
summary, if the noise exposure action values are exceeded then the employer may
be required to:
·
reduce the noise exposure that
produces these risks to as low a level as is reasonably practicable by either
o
reducing noise at source, i.e.
by using quieter equipment, a different process, engineering controls, etc.;
o
reducing noise levels in the
facility, i.e. through sound absorption, keeping noisy machinery away from
quieter areas, screens, barriers, or enclosures; and/or
o
implementing organisational
measures which reduce the length of time that employees are exposed to noise,
i.e. turning off equipment when not in use, introducing job rotation so
employees are doing a mixture of noise and quiet tasks rather than spending all
day working with high noise level equipment;
·
provide employees with hearing
protection if the noise exposure cannot be reduced enough by the aforementioned
measures and the noise levels remain above the exposure action values;
·
provide employees with
information, instruction, and training on noise in the workplace; and
·
carry out health surveillance
where there is a risk because of exposure to loud noise.
Paragraph 66 of Regulation 6 of the NAW Regulations indicates that
the employer should generally be seeking to reduce the risk of noise exposure
irrespective of whether any exposure action values are exceeded. It may also be
necessary to carry out ongoing reviews to the risk assessment at set periods, or
when circumstances change.
Organisational and Technical Measures of
Noise Reduction
Regulation 6 of the NAW
Regulations indicates that “the employer shall ensure that risk from the exposure
of his employees to noise is either eliminated at source or, where this is not
reasonably practicable, reduced to as low a level as is reasonably practicable…..
If any employee is likely to be exposed to noise at or above an upper exposure
action value, the employer shall reduce exposure to as low a level as is
reasonably practicable by establishing and implementing a programme of
organisational and technical measures, excluding the provision of personal
hearing protectors, which is appropriate to the activity.” The table below provides examples of such
measures.
Table 2: Methods of
controlling noise through organisational and technical measures
Action
|
Example Measures
|
Reduce
noise levels at source
|
· Sourcing quieter alternative equipment.
· Using a different quieter working process that achieves the same
production outcome.
· Implement a maintenance programme to ensure that noise levels are
not significantly raised from poorly maintained and old equipment.
· Apply noise silencing or vibration dampening parts to existing
equipment.
· Using anti-vibration mounts to isolate the equipment from the
structure to reduce structure-borne noise throughout a building.
· Attaching silencers to noisy air or gas stream inlets and
exhausts.
· Fitting a noise enclosure around the machine (or the noisy part of
a machine).
· Using active noise control systems around equipment that are
particularly noisy at low frequency.
|
Reduce noise propagation throughout the workplace
|
· Placing noise equipment in an area with fewer employees and
therefore limiting exposure to workers who are not directly operating this
equipment.
· Increasing the distance between the source of noise and the
operator/other works, which could be achieved by a remote control panel in
some cases.
· Directing the noisiest parts of the equipment (i.e. the exhaust of
a compressed air system) away from the working area.
· Using screens and barriers between the sound source and people, to
reduce direct sound.
· Providing a ‘noise haven’ for employees, including operators,
where controlling noise levels at source would be difficult.
· Providing rest facilities where the level of noise exposure is
low.
· Reducing the ‘reverberation time’ in the building by adding
acoustically absorbent material, either retrofitting acoustic paneling/suspended
baffles or by using absorbent surface finishes (such as ceiling tiles and
perforated metal roof liners).
|
Organisational controls
|
· Only operating equipment when strictly necessary and not leaving
noisy equipment to idle.
· Reducing the number of employees working in noisy areas.
· Introducing job rotation so employees are doing a mixture of noise
and quiet tasks rather than spending all day working with high noise level
equipment.
· Training employees on how to reduce their risk to noise exposure,
and potentially developing in-house skills noise control, to ensure that
workers are able to identify when equipment is producing louder than usual
noise levels and how they might be able to reduce this.
· Generally limiting the duration and intensity of exposure to noise,
and having appropriate work schedules with adequate rest periods.
|
Personal Hearing Protection
After the measures with
Regulation 6 (summarised in the previous subsection) have been explored, the
next step is to consider providing personal hearing protection.
Regulation 7 of the NAW
Regulations indicate that hearing protection is compulsory for employees
exposed to levels above the upper exposure action value (UEAV), though this is
not compulsory during the quieter times of the day or if the employee is in a
quiet area. It is also compulsory for any
employee entering a Hearing Protection Zone (HPZ).
Hearing protection is not
compulsory for employees exposed to levels below the UEAV. It is not beneficial to enforce employees to
wear hearing protection when not necessary, as this can lead to isolation,
decreased communication, uncomfortable working conditions and a decreased
ability to hear alarms and sirens.
It is also not strictly beneficial
to use hearing protectors which overprotect, for the reasons above. The main aim of hearing protection is to
reduce noise levels at the ear to below at least the UEAV (85 dB(A)), but they
should be avoided if they reduce noise levels to below 70 dB(A).
The table below shows the
‘single number rating’ (SNR) protection factor that is likely to be suitable
for different levels of noise. The SNR
value is typically stated with the hearing protection device. This is based upon the information in the NAW
Regulations, and in BS EN 458:2004: Hearing protectors.
Table 3: Required
protection factors for hearing protection
A-Weighted Noise Level (dB(A))
1
|
Select a protector with an
SNR of…
|
85 - 90
|
≤20
|
90 - 95
|
20 - 30
|
95 - 100
|
25 - 35
|
100 - 105
|
≥30
|
1 Based on instantaneous noise levels, not
the daily personal noise exposure.
- Higher levels of protection can be achieved through
dual protection, i.e. wearing ear-muffs over ear-plugs.
|
There are several other factors
that influence the choice of which type of hearing protector an employee may
wish to use, as outlined in Part 5 of the NAW Regulations, which also state
that “wherever possible the employer should make more than one type of
protector available (making sure that each is suitable for the noise and jobs
to be done) to allow the user a personal choice”.
Employees are often reluctant to
use hearing protection, are forgetful, or do not apply protection
correctly. A programme of monitoring,
supervision, warning notices, instruction, and training is needed to ensure
they are used. It is also important that
a system of maintenance is employed, to ensure that the hearing protection
maintains its level of noise reduction and does not become defective over time.
Regulation 7 of the NAW
Regulations indicates If
any area in the workplace is likely to be exposed to noise levels at or above the
upper exposure action value (UEAV) then the employer must ensure that:
·
the area is designated a
Hearing Protection Zone (HPZ);
·
the area is demarcated and
identified by means of the sign specified for the purpose of indicating that
ear protection must be worn;
·
access to the area is
restricted where this is practicable and the risk from exposure justifies it;
and
·
no employee enters that area
unless that employee is wearing personal hearing protectors, so far as is
reasonably practicable.
The boundaries of HPZs should
be considered carefully, i.e. they should avoid overlapping commonly used
walkways and should not extend further than is necessary to protect people
carrying out their normal work. In
situations where the boundaries of a zone cannot be marked, then attaching
hearing protection zone signs to specific tools is an appropriate alternative.
Regulation 10 of the NAW
Regulations indicates that the employer must provide ‘information, instruction,
and training’ to employees who are exposed to above the LEAV. It is important for the employer to tell
employees:
·
their likely level of noise
exposure and the health risk this carries;
·
what the employer is doing to
control risks and exposure to noise;
·
when and how the employee can
obtain hearing protection and when they should use it;
·
how the employee should be
using hearing protection and noise control equipment in the correct way to
minimize their risk, and how they can identify and report defects;
·
what the employees’ duties are
under the NAW Regulations; and
·
how the employer is providing a
health surveillance system; and
·
what symptoms of hearing damage
the employee should look out for, and to whom and how they should report this.
This information, instruction,
and training can be provided in any way, providing the employee can find it easy
to understand. The HSE’s ‘Noise:
Don’t lose your hearing!’ pocked card can be handed out to supplement this.
It is also a requirement to
discuss the risk assessment and all plans relating to controlling noise
exposure with a trade union-appointed safety representative, or for groups of
workers not covered by this, an elected employee representative.
Health Surveillance
Regulation 9 of the NAW
Regulations state that there is significant evidence which links the regular
exposure to noise levels above the exposure action values to long term health
risks and hearing damage. Therefore, the
employer should provide health surveillance to:
·
all employees who are regularly
exposed to noise levels above the upper exposure action values (UEAV); or
·
employees who are occasionally
exposed above the UEAV, or who are exposed between the lower (LEAV) and upper
(UEAV) thresholds but who are known to be particularly sensitive to
noise, i.e. from medical history, audiometric testing or a history of noise
exposure at previous jobs, or a family history of early-onset deafness.
Health surveillance is a
programme of health checks which usually involves regular hearing checks
(audiometric testing), keeping health records, and referring employees to a
doctor if/when hearing damage is identified.
It is useful in waring employees if they exhibit early signs of hearing
damage to give the opportunity to do something to prevent the damage from
getting worse. It is also effective for
the employer to identify whether noise control measures are working.
Surveillance can be introduced at
any time for existing employees and should be introduced straightaway for new
employees, to allow a baseline to be taken.
Annual checks for the first two years (followed by three-yearly checks
after this unless a problem is detected or the risk of hearing damage is high)
should be conducted by someone with appropriate training, with the whole
surveillance programme under the control of an occupational health
professional.
Regulation 5 of the NAW
Regulations indicate that the employer should implement an ongoing control
programme in managing noise exposure risks.
It may be necessary to review and produce an updated risk assessment
when circumstances change, for example, if:
·
circumstances change in the
workplace, i.e. new equipment is installed, older machinery ceases to be used,
shift patterns are changed, any reason that employees’ level of noise exposure
may have changed;
·
noise control measures have
been implemented since the previous assessment and the impact on employees’
exposure needs to be re-assessed;
·
the employer becomes aware of
improved working methods and noise-control techniques that are new to the
industry and could be applied to the workplace;
·
control measures that could not
be implemented at the time of the original assessment become more viable to do
so, i.e. because of new technology or reduced costs; and/or
·
continued health surveillance
shows that employees’ hearing is being damaged, suggesting that noise control
methods are not being properly implemented or are not effective enough.
The NAW Regulations indicate that
even if none of the points above are true, the assessment should still be
reviewed at least every two years.
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