Noise at Work
The last 40 years have seen greatly increased awareness about the dangers of noise at work, and this has been reflected in European Directives and thus in British legislation, notably the introduction of the Noise at Work Regulations 1989 and more recently The Control of Noise Regs 2005.
The main differences from the 1989 Noise Regulations are:
•the two action values for daily noise exposure have been reduced by 5 dB to 85 dB and 80 dB respectively;
•there are now two action values for peak noise these being set at 135 dB and 137 dB;
•there are new exposure limit values of 87 dB (daily exposure) and 140 dB (peak noise). These two values take into account the effect of wearing hearing protection and which must not be exceeded;
•there is a specific requirement to provide health surveillance where there is a risk to health.
How is noise measured?
Noise is measured in decibels, and as far as noise at work is concerned, it is measured for average or peak noise values. For measuring average noise an 'A, weighting', written as 'dB(A)', is used, whereas a 'See weighting', written as 'dB(C)', is used to measure peak, impact or explosive noises.
In terms of changes in sound level you might just notice a 3 dB change in noise level, this because of the way our ears work. Yet every 3 dB doubles the noise, so what might seem like small differences in the numbers can be quite significant. E.g. 83 dB is twice as loud as 80 dB. Looking at this in a different way 80 dB + 80 dB equals 83 dB, and not as you might think 160 dB.
Typical noise levels:
•20 dB equates to a quiet room at night.
•40 dB is like a quiet sitting room.
•60 dB can be compared to an ordinary spoken conversation.
•80 dB is like people shouting.
•110 dB can be compared to a pneumatic drill nearby.
•130 dB is like an aeroplane taking off 100 meters away.
•140 dB is the threshold at which noise is painful to listen to for most people, although some people may find lower levels painful too.
The noise level in a quiet countryside is typically 20 to 30 dB, this due to the wind, leaves and birds etc. In contrast in a city or town, a very loud sound such as a pneumatic drill may exceed 100 dB.
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