Noise

Sean Whitakerin Training & Education
Think of the noisy activities you might encounter in your work: mowing, tractor driving, 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.

Table: Typical noise levels

Equipment

dB(A)

Tractor cab

80-85

Lawn Mower

88-94

Power drill

90-100

Air Compressor

90-93

Leaf Blower

95-105

Circular Saw

100-104

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 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.


Table: The limits imposed by the Control of Noise at Work Regulations 2005

Name

Value

Measured where?

Lower exposure action value

80dB(A) daily or weekly exposure level

135dB(C)peak sound pressure

At source

Upper exposure action value

85dB(A) daily or weekly exposure level

137dB(C) peak sound pressure

At source

Exposure limit value

87dB(A) daily or weekly exposure level

140dB(C) peak sound pressure

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.

Step 2) Calculate the daily or weekly noise exposure by entering the noise levels and their durations into the noise exposure calculator at the HSE web page www.hse.gov.uk/noise/calculator.htm - it's very simple to use.

The calculator takes account of the time you or your staff spend with different pieces of equipment. For example, if one of your workers has a quick blast or two with a leaf blower, followed by a few hours quietly marking-out pitches, s/he will have a fairly trivial noise exposure value for the day. But a whole eight hours of leaf blowing - perish the thought - might put the day's exposure value above at least one of the exposure action values.

Step 3) Having calculated the noise exposure values, you must take measures to reduce noise exposure if you or any of your staff are likely to exceed the action values or the limit value. The Regulations describe clearly what you need to do. It's useful to consider remedial actions in terms of four main areas: hearing protection, training, reducing noise, and health surveillance.

When noise levels equal or exceed the lower exposure action value:

Hearing protection: Employers must make hearing protection available and advise on its effective use. It need not be worn, but it must be made available.

Training: Staff should be told about (a) the risks posed by noise, (b) the action levels and the exposure limit value, (c) the results of the noise risk assessments, (d) the availability and provision of personal hearing protection, and (e) safe working practices to minimise exposure to noise.

Health surveillance: Staff should know about (a) how to detect and report signs of hearing damage and (b) their entitlement to health surveillance and its purposes.

At or above the upper exposure action value stricter requirements apply:

Hearing protection: This is compulsory and the employer must use signs to designate the zones where it is required.

Reducing noise: Noise must be reduced as far as reasonably practicable by (a) adopting different work methods, (b) buying quieter equipment or using noise insulation, (c) improving the design and layout of workplaces, (d) adopting appropriate maintenance programmes for work equipment, the workplace and work systems, and (e) imposing limits on the duration and intensity of noise exposure.

Training: Suitable and sufficient training must inform employees how to minimise their exposure to noise. Employees should be advised how to use hearing protection effectively.

Health surveillance: A comprehensive screening programme is necessary, including a means for staff to report high noise levels and hearing damage, and a method of monitoring the hearing of staff.

As for the exposure limit value, this is an area into which noise levels must never stray - avoid it at all costs!

Step 4) Next develop a plan of action and check periodically that it is being followed. Hold onto the risk assessment and the action plan. You might need to revisit them when work arrangements change. For example, new equipment might be used or perhaps some of your staff will shortly work on a new site.
These steps will be the basis for managing the risks of noise at your work place.

For more information have a look at the free HSE leaflet called Noise at Work: Guidance for Employers on the Control of Noise at Work Regulations 2005, available at www.hse.gov.uk/pubns/indg362.pdf, and Protect your hearing or lose it!, available at www.hse.gov.uk/pubns/indg363.pdf. Both leaflets are also available by post from the HSE on request.

This article was sponsored by InterAction of Bath, specialists in health and safety advice and assessments, including noise assessments.

Sean Whitaker
(Human Factors and Safety Consultant)
InterAction of Bath Ltd.
5 / 6 Wood Street
Bath
BA1 2JJ
United Kingdom
Tel. + 44 (0) 1225 482 882




Article Tags:
Training & education