NOISE
drilling, strimming, maybe some stone cutting, perhaps even shooting. If you or your staff do any of these jobs you’ll have to think carefully about noise as a work hazard. A Medical Research Council survey for 1997 to 1998 suggested that over half a million workers in the UK suffer some level of work- related hearing damage - a surprisingly high proportion of the workforce. Yet work- related hearing damage is entirely avoidable in this enlightened world of work. Noise is measured in decibels, usually weighted for the sensitivity of the human ear, abbreviated to dB(A). The faintest audible sounds are 0dB(A); loud conversation is around 60dB(A); and a road drill delivers around 100dB(A). You can find a few other examples below.
T
Table: Typical noise levels Equipment Tractor cab Lawn Mower Power drill
Air Compressor Leaf Blower Circular Saw
dB(A) 80-8 88-9 90-1 90-9 95-1
hink of the noisy activities you might encounter in your work: mowing, tractor driving,
Table: The limits imposed by the Control of Noise at Work Regulations 2005
Name Lower
Value
exposure weekly exposure action value
80dB(A) daily or level 135dB(C)
peak sound pressure
Upper
Measured at source 85dB(A) daily or
exposure weekly exposure action value
Measured at source
85 94
100 93
105 100-1 104
A more useful measure of noise is called a noise exposure value, which averages all noise levels experienced by a particular person across a specified time period, usually a working day or week. Respectively, daily and weekly exposure values are referred to as LEP,d or LEP,w. For brief loud noises, such as a gunshot, the peak sound pressure of the noise is more relevant, and in this case the unit is dB(C). The Control of Noise at
Work Regulations 2005 set the legal requirements for
Exposure 87dB(A) daily or limit
value weekly exposure
level 140dB(C) peak sound pressure
Measured inside hearing protection
The Regulations also state the actions that employers must take to reduce the risks posed by noise. The process is actually quite simple:
Step 1: Begin with a risk assessment. List all the jobs that are noisy and then estimate their noise level in decibels. Ideally you would measure the noise with a noise meter, but as a last resort you could make estimates using the examples given earlier. Be pessimistic with your judgements of noise to allow a margin of safety. Make sure your risk assessment is contained in a document that can be stored, either as a hardcopy or on computer.
level 137dB(C) peak sound pressure
limiting work-related noise risks in the UK. The Regulations came into force on the 6th April this year, tightening up parts of the Noise at Work Regulations 1989. Perhaps most importantly they define three noise levels, as shown in the table. The actions required of the employer at each level will be explained in a moment.
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