Introduction to Health and Safety at Work

action
level 
values and exposure 
limit
values.
An exposure action value is a level of noise at which 
certain action must be taken.
An exposure limit value is a level of noise at the 
ear above which an employee must not be exposed. 
Therefore if the workplace noise levels are above this 
value, any ear protection provided to the employee must 
reduce the noise level to the limit value at the ear.
These exposure action and limit values are:
1. The lower exposure action levels are:
(a) 
a daily or weekly personal noise exposure of 
80 dB(A)
; and
(b) a peak sound pressure of 
135 dB(C)
2. The upper exposure action levels are:
(a) 
a daily or weekly personal noise exposure of 
85 dB(A)
; and
(b) a peak sound pressure of 
137 dB(C)
3. The exposure limit values are:
(a) 
a daily or weekly personal noise exposure of 
87 dB(A)
; and
(b) a peak sound pressure of 
140 dB(C)
.
The peak exposure action and limit values are defi ned 
because high level peak noise can lead to short-term 
and long-term hearing loss. Explosives, guns (including 
nail guns), cartridge tools, hammers and stone chisels 
can all produce high peak sound pressures.
If the daily noise exposure exceeds the lower 
exposure action level, then a noise assessment should be 
carried out and recorded by a competent person. There 
is a very simple test which can be done in any workplace 
to determine the need for an assessment. Table 15.6 
gives information on the simple test to determine the 
need for a noise risk assessment.
If there is a marked variation in noise exposure levels 
during the working week, then the regulations allow a 
weekly rather than daily personal exposure level, (L
EP,w
), 
to be used. It is only likely to be signifi cantly different 
to the daily exposure level if exposure on one or two 
days in the working week is 5 dB(A) higher than on the 
other days, or the working week has three or fewer days 
of exposure. The weekly exposure rate is not a simple 
arithmetic average of the daily rates. If an organization is 
considering the use of a weekly exposure level, then the 
following provisions must be made:
➤
hearing protection must be provided if there are very 
high noise levels on any one day
➤
the employees and their representatives must be con-
sulted on whether weekly averaging is appropriate
➤
an explanation must be given to the employees 
on the purpose and possible effects of weekly 
averaging.
Finally, if the working day is 12 hours, then the action 
levels must be reduced by 3 dB(A) because the action 
levels assume an 8-hour working day.