Introduction to Health and Safety at Work

continuous equivalent noise level (L
Eq
)
which is normally measured over an 8-hour period.
Direct reading devices, which tend to be much 
cheaper, can be used successfully when the noise levels 
are continuous at a near constant value.
Table 15.5
Some typical sound pressure levels (SPL) 
dB(A) values
Activity or environment 
SPL (dBA)
Threshold of pain 
140
Pneumatic drill 
125
Pop group or disco 
110
Heavy lorry 
93
Street traffi c 
85
Conversational speech 
65
Business offi ce 
60
Living room 
40
Bedroom
25
Threshold of hearing 
0

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Introduction to Health and Safety at Work
262
Another important noise measurement is the 
daily 
personal exposure level
of the worker, 
L
EP,d
, which 
is measured over an 8-hour working day. Hence, if a 
person was exposed to 87 dB(A) over 4 hours, this would 
equate to a L
EP,d
of 84 dB(A) since a reduction of 3 dB(A) 
represents one half of the noise dose.
The HSE Guidance on the Control of Noise at Work 
Regulations, L108, offers some very useful advice on the 
implementation of the Regulations and should be read by 
anyone who suspects that they have a noise problem at 
work. The guidance covers ‘equipment and procedures 
for noise surveys’ and contains a noise exposure ready-
reckoner which can be used to evaluate L
EP,d
when the 
noise occurs during several short intervals and/or at 
several different levels during the 8-hour period.
Noise action levels
Regulation 6, of the Control of Noise at Work Regulations 
places a duty on employers to reduce the risk of dam-
age to the hearing of their employees from exposure to 
noise to the lowest level reasonably practicable.
The regulations introduce exposure