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Don’t Turn a Deaf Ear

Published: 10th Oct 2008

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The requirements of the new European Noise Directive on the minimum health and safety requirements regarding the exposure of workers to noise [Directive 2003/10/EC of the European Parliament and of the Council of 6 February 2003] change the conditions of design and testing for some types of hearing protectors as well as the conditions for selection and use of all types of hearing protectors. Stakeholders responsible for health and safety in companies need to know details on changes which have to be considered within the selection of hearing protectors and their consideration within the risk assessment.

In addition the implementation of the new noise directive to national regulations by European member states differs from member state to member state. In this regard the worldwide discussion on “how to consider real world attenuation” effects the approaches selected by European member states for implementation of the new European Noise Directive. Companies active in more than one European member state may have to apply various rules for the selection and use of hearing protectors and their consideration within the risk assessment.

Old European Noise Directive

A historical retrospection on European Noise Control reveals that on 12 May 1986 the Council Directive [86/188/EEC] on the protection of workers from the risks related to exposure to noise at work was published in the Official Journal of the European Communities. Article 13 of this Council Directive specified that the Member States had to bring into force the laws, regulations and administrative provisions necessary to comply with the Directive by 1 January 1990. Those regulations and administrative provisions have been established and are well known today in European companies.

New European Noise Directive

But the new European Directive [2003/10/EC] on noise exposure was published on 15-02-2003. Member States had to bring into force the laws, regulations and administrative provisions necessary to comply with the Directive before 15 February 2006. Two exemptions were specified:

  • Personnel on board seagoing vessels: If necessary Member States may have an additional period of five years from 15 February 2006 to implement the provisions of Article 7 of the Directive
  • Music and entertainment sectors: In order to allow for a drawing up of a code of conduct providing for practical guidelines for the implementation of the provisions of the Directive, Member States shall be entitled to make use of a maximum transitional period of two years from February 2006

In case a hearing protector has to be used to achieve the worker’s appropriate protection against noise the old and the new directive are different referring to the consideration of the hearing protectors’ attenuation within the risk assessment:

Approach of the old European Noise Directive

  • Assessment: Article 3 of old Noise Directive [86/188/EEC] specified that the employer should assess noise experienced at work and, when necessary, measure that noise. For the assessment of noise exposure the attenuation of hearing protection was not taken into account
  • Measures: In case the assessment shows, that exposure action values are exceeded, the employer shall take appropriate measures to reduce the noise exposure
  • Use of hearing protectors: In case neither technical nor organisational measures could reduce the noise exposure of workers sufficiently, and
    • • where the exposure is likely to exceed 85 dB (A), personal hearing protectors must be made available to workers and
    • • where the daily personal noise exposure of a worker exceeds 90 dB(A) or the maximum value of the unweighted instantaneous sound pressure is greater than 200 Pa, personal hearing protectors must be used

Article 6 of the old Noise Directive [86/188/EEC] specified that hearing protectors are deemed suitable and adequate if, when properly worn, the risk to hearing can reasonably be expected to be kept below the risk arising from the exposure exceeding the daily noise exposure of 90 dB(A). I.e. for the assessment of the efficiency of the hearing protection used an “expectation” not to exceed 90 dB(A) was enough. Therefore in practice the selection and use of PPE against noise was separated from the risk assessment:

  • Indeed the protection level determined within the risk assessment was used to select PPE
  • The level effective to the user’s hearing (under the protector) was not assessed within the risk assessment

Approach of the European PPE Directive

The PPE Directive [89/686/EEC] specifies in Annex II, clause 3.5:

  • “PPE designed to prevent the harmful effects of noise must be capable of attenuating the latter to such an extent that the equivalent sound levels perceived by the user do not under any circumstances exceed the daily limit values laid down by Council Directive 86/188/EEC (old Noise Directive)... .”

Fig. 2: Ear muff in use in construction industry. Picture: Deutsche Gesetzliche Unfallversicherung, 53757 Sankt Augustin, Germany

The PPE Directive is addressed to manufacturers of PPE, the Notified Bodies responsible for testing and certification under the PPE Directive [89/686/EEC] and member states. Therefore in the past only manufacturers and Notified Bodies (and sometimes the market surveillance of the member states) had to assess the performance of hearing protectors by testing. The employer used only the laboratory data to select PPE as guided by e.g. [EN 458:2004 - Hearing protectors - Recommendations for selection, use, care and maintenance - Guidance document]. But he did not assess the level effective to user’s hearing.

Table 1: Comparison of new and old European Noise Directive
Exposure limit values and exposure action values Directive 2003/10/EG (06/02/2003) Directive 86/188/EEC (12/05/1986)
Lower exposure action values L EX,8h = 80 dB(A) or p peak = 112 Pa (135 dB(C)) L r = 85 dB(A) or L peak = 140 dB (200 Pa)
Upper exposure action values L EX,8h = 85 dB(A) or p peak = 140 Pa (137 dB(C)) L r = 90 dB(A) or L peak = 140 dB (200 Pa)
Exposure limit values (attenuation provided by ind. hearing protection shall be taken into account) L EX,8h = 87 dB(A) or p peak = 200 Pa (140 dB(C)) not existing

Approach of the new Noise Directive

An excerpt of the “reasons of consideration” found in the new Noise Directive [2003/10/EC] shows interesting background information and items of a new approach compared to that approach of the old Noise Directive [86/188/EEC]:

  • Current scientific knowledge of the effects... is not sufficient to enable precise exposure levels covering all risks to health and safety, ...
  • Exposure limit values are needed to avoid irreversible damage to workers’ hearing; the noise reaching the ear should be kept below the exposure limit values
  • The particular characteristics of the music and entertainment sectors require practical guidance; Member States should be entitled to make use of a transitional period for the development of a code of conduct

The old Noise Directive [86/188/EEC] did not provide any exposure limit value. Table 1 shows a comparison of exposure action values and exposure limit values of the old and the new Noise Directive.

The lower and upper action values were lowered by 5 dB(A) by the new Noise Directive [2003/10/EC].

Two basic types of hearing protectors

Conventional hearing protectors

Conventional hearing protectors attenuate external sound in a way, that the external sound perceived by the user is reduced by the attenuation provided by the protector.

Hearing protectors with sound restoration

Sound restoration inside hearing protectors is used for e.g.

  • Communication (wireless or by wire)
  • Level-dependent transmission of external sound at the user’s workplace to his hearing via an electro-acoustic transmission path or
  • Entertainment via a built-in broadcast receiver

Assessing the sound perceived by the user we have to consider for this type of protectors two components:

  • External sound reduced by the conventional attenuation of the hearing protector and
  • The component produced by the in-build loudspeakers of the hearing protector

Requirements for selection and use of hearing protectors

As already mentioned the PPE Directive [89/686/EEC] specifies in Annex II, clause 3.5 referring to the old Noise Directive [86/188/EEC], that the maximum level perceived by the user shall not exceed the daily limit value of 90 dB(A).

The New Noise Directive [2003/10/EC] requires, that the maximum level perceived by the user shall not exceed 87 dB(A).The reduction of the maximum level perceived by the user of 3 dB(A) by the new Noise Directive [2003/10/EC] can be reached for conventional protectors by selection of protectors offering higher attenuation values.

But for sound restoration protectors offered as complete solutions the sound level generated by the loudspeakers at user’s ear cannot be reduced by selection of other protectors because the remaining sound level inside the protector is pre-determined only by the settings taken by the manufacturer during design of the hearing protector.

But this problem was already solved several years ago by some forward-looking member states: They reduced already 1989 the upper action level from 90 dB(A) to 85 dB(A) by their transposition of the old Noise Directive [86/188/EEC] to their national law. Thereon for the free movement of sound restoration protectors on the European market the maximum allowed level was reduced to 85 dB(A) in the relevant European harmonised testing standards for hearing protectors. Therefore for sound restoration protectors offered as complete solutions it is not necessary to adapt to the new situation created by the new Noise Directive [2003/10/EC] referring to the sound level generated by the built-in loudspeakers.

For the component reduced by the conventional attenuation of the hearing protector the same applies as for conventional protectors. But for sound restoration protectors which are not provided as complete solutions and which are used in combination for example with a radio the employer has to assess the level perceived by the user under the protector within his risk assessment. He has to guarantee not to exceed the limit value laid down by the new Noise Directive [2003/10/EC].

Fig. 3: Professional training in wood industry. Picture: Deutsche Gesetzliche Unfallversicherung, 53757 Sankt Augustin, Germany

Approaches to consider “real world” attenuation

To consider “real world” attenuation specified figures have to be subtracted from the attenuation figures provided by the manufacturers. In Germany the fixed reductions of 3 dB for custom moulded ear plugs, 5 dB for ear muffs and 9 dB for other types of ear plugs are recommended. In cases where special measures are applied to ensure effective protection - e.g. special training, motivation and exercise provided to the users and check of usage - the subtraction may be omitted. In United Kingdom it is recommended to subtract four dB for all kind off hearing protection devices. In Italy it was specified: In case of risk octave band calculation with a “statistical range enlargement” of 3 s should be used.

All member state approaches known up to now use data obtained within EC-type examination and which are to be specified by the manufacturer in the user information.

During the various discussions on the transposition of the new Noise Directive [2003/10/EC] another possibility was taken into consideration: The measurement of levels under the protectors. The corresponding suitable measurement technique is known as MIRE(microphone in real ear)-technique and specified by [ISO 11904-1:2002]. But this technique is a laboratory one and can only be used by specialists. Because of its risks - damage of the ear drum - it is not of practical use for application of the new Noise Directive [2003/10/EC].

Custom moulded ear plugs

An European expert committee on hearing protection recommended in 2007 an additional check of custom moulded ear plugs’ attenuation before putting into service. This additional check has to be carried out by the manufacturer in order to avoid leakage and by that lack or decrease of protective function. Those relevant leakages have been observed on brand-new products by manufacturers as well as health and safety experts. The leakages occur frequently and can only be avoided by a final check of the product’s protective function when placed in the user’s ear canal. This check is considered to be necessary to fulfil the relevant European Directives.

PPE selection for the music and entertainment sector

Hearing is the musicians’ capital. Their total exposure is frequently not known by the employer because musicians often have additional engagement (giving lectures...). Hearing protector selection is difficult, because the requirements are individually very diverse. Therefore a simple selection tool was developed to be used by the musicians themselves, employed in classical orchestra, and who don’t need any expertise in acoustics (e.g. sound levels) to use that tool. This selection is available (in German) at:

http://www.dguv.de/bgia/de/pra/softwa/musiker/index.jsp

Published: 10th Oct 2008 in Health and Safety International

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