BS EN 458:1994 download free

06-04-2021 comment

BS EN 458:1994 download free.Hearing protectors Recommendations for selection , use ,  care and maintenance Guidance document.
0 Introduction
Hearing protection devices are items of personal protection equipment which as a result of their attenuation properties, reduce the effects of noise on hearing, in order to avoid hearing damage.
BS EN 458 has been prepared to give guidance to all persons who have to supply, purchase or wear hearing protectors, and to encourage the use of effective criteria in their selection, use, care and maintenance.
In order that the protection offered by hearing protectors be effectively realized, hearing protectors should be used all the time that the user is in a potentially hazardous noise environment. In the selection of hearing protectors, attention is therefore drawn to the importance of considering factors which may influence comfort and acceptance.
in hearing conservation programmes, measures other than personal hearing protection, such as the identification of noise areas, assessment of personal noise exposure, and noise abatement, require attention as a priority, as shown in Figure 1.
1 Scope
BS EN 458 gives recommendations for the selection, use, care and maintenance of hearing protectors.
Special types of hearing protectors are outside the scope of this standard, although they are classified in 4.4, and some of the guidance will be relevant to them.
2 Normative references
BS EN 458 incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to BS EN 458 only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 352-1:1992, hearing protectors — Safety requirements and testing — Part 1: Ear-muffs.
EN 352-2:1992, Hearing protectors — Safety requirements and testing — Part 2: Ear-plugs.
EN 457:1990, Danger signals for workplaces — Auditory danger signals.
4 Classification
4.1 Ear-muffs
Ear-muffs consist of cups which fit over the ears and are sealed to the head with soft cushions usually filled with plastic foam or liquid. The cups are usually lined with sound absorptive material. They are connected by a tensioning band (headband), usually made of metal or plastics. A flexible headstrap is sometimes fitted to each cup or to the headband close to the cups. This strap is used to support the cups when the headband is worn behind the head or under the chin. Some ear-muffs have one cup intended only for the left ear and another only for the right ear. Ear-muffs may be available in “normal” and “restricted size range” types.
“Normal” size ear-muffs are intended to fit the majority of head sizes to be found in the working population in Europe. “Restricted size range” ear-muffs are designed to fit particular head sizes, “small size range” and “large size range” ear-muffs may be available.
4.1.1 Types of bands connecting the cups Ear-muffs are available with headbands, neckbands, chinbands, nosebands and universal bands. Ear-muffs with neckbands and chinbands permit the simultaneous wearing of a safety helmet. Universal bands can be worn over the head, behind the head, or under the chin. Universal bands, neckbands and chinbands may be complemented by headstraps to ensure a reliable fit of the muff.
4.1.2 Helmet mounted ear-muffs
These consist of individual cups attached to arms fixed to an industrial safety helmet and are adjustable so that they can be positioned over the ears when required.
4.2 Ear-plugs
These are hearing protectors which are inserted and worn in the ear canal, or in the ear cavity, intended to seal its entrance. They are sometimes provided with an interconnecting cord or headband. Ear-plugs fall into two categories:
disposable — intended for one fitting only; reusable — intended for more than one fitting.
4.2.1 Premoulded ear-plugs
Premoulded ear-plugs can readily be inserted into the ear canal without prior shaping. Premoulded ear-plugs are usually made of soft forms of glass down, silicone, rubber or plastics. They can be available in a range of sizes.
Compatibility with other headgear such as helmets, spectacles, etc.
5.2 Certification mark
Only hearing protectors marked with an appropriate certification mark of conformity should be selected (for an example see Figure 2).
5.3 Sound attenuation requirement
5.3.1 General
It is desirable for a protector to reduce the noise level at the wearer’s ears to below the action level. However, consideration also needs to be given to avoid isolation of the wearer thereby adding to their difficulty in perceiving sounds (see Figure 3 and 5.3.4).
5.3.2 Selection of hearing protectors according to their sound attenuation
The procedures recommended for estimating the effective A-weighted noise level at the ear when hearing protectors are worn are given in Annex A and Annex B. Preference should be given to the procedures as given in A.2, then A.3, A.4, A.5 in that order.
5.3.3 “Real-world” attenuation
The attenuation data used to estimate the noise level at the ear when hearing protectors are worn is that derived from the subjective threshold test of EN 24869-1. Although this method uses a number of human subjects who fit the protector themselves for the test, the performance achieved in the “real-world” may be lower than that obtained in the laboratory test because of poor fitting, long hair, or the wearing of spectacles or other protective clothing.
This reduction in attenuation in the “real-world” will itself vary from product to product. It can be minimized by correct fitting (see 6.6).
5.3.4 Effect of over-protection
Caution should be exercised against selecting hearing protectors which provide unnecessarily high attenuation. Such devices might cause communication difficulties or be less comfortable than devices with lower attenuation, and therefore they would be worn for less of the time (see Figure 3).
6.1 General
In order to avoid resistance to the wearing of hearing protectors, effective explanation for their need is required. Lack of motivation is sometimes due to insufficient instruction or unsuitable selection. For example, a sense of isolation may be experienced when first wearing hearing protectors.
6.2 Period of use
To be effective, hearing protectors need to be worn all the time that persons are exposed to harmful noise levels. If they are removed for even short periods the effective protection is greatly reduced as shown in Figure 4.
Where people fail to wear hearing protectors all of the time they are in noise, the limiting factor will become the time spent without protectors rather than the performance of the protectors.
6.3 Hearing protectors designed for use in particular orientations
In cases where hearing protectors have one cup or one plug intended only for the left ear and another for the right ear, care should be taken to ensure that the hearing protectors are worn in the correct orientation.
6.4 Availability of protectors
Personnel should be aware that they are not to enter noise hazard areas without wearing hearing protectors.
Where disposable protectors are used, a supply should be available at normal points of entry to the noise hazard areas. If appropriate, additional provision should be made to provide hearing protectors to visitors.
6.5 Compatibility of other headgear and/or clothing with ear-muffs and banded ear-plugs
6.5.1 General
It is not uncommon to find that personnel working in a noisy area may be required to wear other protective headgear which can lead to a reduction in performance. Special attention should be paid to the aspects described in the following sections when ear-muffs or banded ear-plugs are worn.
6.5.2 Protective clothing
Protective clothing should be worn over any hearing protection and not underneath. Any attempt to wear ear-muffs or banded ear-plugs over clothing will greatly reduce their effectiveness.
7.4 Inspection and replacement
Hearing protectors should be inspected at frequent intervals to identify protectors that are damaged by mechanical failure, ageing, accident or abuse. Headbands may be subject to intentional or accidental deformation and should be checked for geometry against an unused example of the protector if there is any suggestion of loss of force.
Cushions of ear-muffs must be replaced in accordance with the manufacturer’s instructions as soon as they no longer retain their shape, become hard or brittle, show evidence of cracks, or otherwise lose their performance.
Replacement parts or new products must be available.
7.5 Guidance for maintenance Information for care and maintenance should be given to all persons who will need to wear hearing protectors (see 7.2. 7.3. 7.4), and repeated at regular intervals.
7.6 Disposal
Disposal arrangements for used hearing protectors should ensure that they cannot be inadvertently re-used and that they do not cause environmental damage.

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