Noise

INTRODUCTION

Exposure to high noise levels can cause incurable hearing damage. Usually the important factors are:-

(i)  The noise level (given in decibels, as dB(A))

(ii) The extent of exposure.

The damage involves loss of hearing ability, sometimes made worse by permanent "ringing in the ears" (tinnitus).

LEGAL REQUIREMENTS

The Noise at Work Regulations 2005 contain requirements where noise exposure is likely to be at or above any of three Action Levels (ALs). Two of the Action Levels are values of 'daily personal exposure to noise', shortened to LEP,d. These depend on the noise level in the working area and how long people spend in them during the day. The First Action Level is an LEP,d of 85dB(A) and the Second Action Level is an LEP,d of 90dB(A). There is also a Peak Action Level of 200 pascals (equivalent to 140dB), most likely to be important where loud impulsive sources (e.g. cartridge operated tools) are used, sometimes only occasionally.

How is noise measured?
Noise is measured in decibels (dB). An 'A-weighting' sometimes written as 'dB(A)', is used to measure average noise levels, and a 'C-weighting' or 'dB(C)', to measure peak, impact or explosive noises. You might just notice a 3 dB change in noise level, 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.

DECIDING WHAT TO DO

• As a 'rule of thumb' indicator of likely noise level, if you have to raise your voice to be heard when standing next to a person this is approximately 80db(A)
• The use of the following Action Plan may help you decide what you should do:-
• The assessment of noise exposure should be done by a competent person. Records of assessments should be kept, until superseded. Published advice is available on practical ways to quieten the workplace (See References/Further Details). Machinery Suppliers and Trade Associations may also be sources of useful information or help.
• Noise reduction methods can be placed in a hierarchy, as follows :-

(i) reduce noise at source - better equipment; isolation; enclosure

(ii) increase distance from source

(iii) provide baffles

(iv) reduce time spent in area/rotate staff

(v) personal protective equipment (e.g. ear defenders)

Prevention is always better than cure. Choosing quieter machinery from the start can save you the cost of introducing noise reduction measures once it is installed. You may wish to consider introducing a 'Positive Noise Reduction Purchasing Policy' i.e. preparing a strategy for controlling the impact of noisy machinery in the workplace. The leaflet 'Keep the Noise Down - Advice for Purchasers of Workplace Machinery' contains useful information which will help you when discussing machinery specififcations with potential suppliers and when considering noise reduction strategies.

• The use of ear protection should not be regarded as a substitute for noise reduction.
• Ear protection zones (where exposure is to the Second Action level of 90 dB(A)) should be marked with notices:-