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Comprehensive protection by use of PPE against the hazards at work requires more than proper selection based on the protection level needed: The PPE user directive (Council Directive 89/656/EEC, Official Journal of the European Communities L 393, 30/12/1989 p. 0018 - 0028) requires an assessment of personal protective equipment itself, which has to consider the risks which may be introduced by use of PPE or use of combinations of PPE. As an example risks which may be introduced by use of hearing protectors are described. Assistance in the assessment required by PPE user directive (Council Directive 89/656/EEC, Official Journal of the European Communities L 393, 30/12/1989 p. 0018 - 0028) and in selection and use of hearing protectors with regard to this assessment is presented.
Keywords: risks by use of personal protective equipment (PPE), expert program, assessment of personal protective equipment (PPE), hearing protector, selection, signal audibility, speech perception
How to cite this article:
Liedtke M. Risk by use of hearing protectors--expert programme supports SMEs in appropriate selection and use. Noise Health 2005;7:31-7 |
| Introduction | |  |
Risk by use of hearing protectors:
Hearing protectors shall protect against the harmful effects of noise. But there are some risks which may occur by use of hearing protectors itself - e.g. inadequate attenuation performance of protectors may result in decrease of acoustic warning signal audibility and speech perception which can increase the risk of accidence.
Risk by use of combinations of personal protective equipment (PPE): Looking at the activity of an employee maintaining the equipment of a large plant in steel industry who uses a hand-held grinding machine the risk assessment results e.g. in using head protection, hearing protection and eye protection. Combination of an ear muff and an industrial safety helmet is not possible for ear muffs equipped with an over-the-head band. In case such an ear muff is provided to an user in addition to a helmet he can only protect himself against one of the two hazards. Combination of safety glasses and ear muff can result in leakage of the ear muff's cushions caused by the side arms of safety glasses. This reduces the protection level of the ear muff and may result in an unexpected high noise exposure of the user.
Documents assisting in selection and use of PPE
Assistance in selection and use of PPE is given in the Council Directive 89/656/EEC of 30 November 1989 on the minimum health and safety requirements for the use by workers of personal protective equipment at the workplace (Council Directive 89/656/EEC, Official Journal of the European Communities L 393, 30/12/1989 p. 0018 - 0028)[1]. This directive is available in several languages at
http://europa.eu.int/eur-lex.
Especially for the assistance of small and medium sized enterprises (SMEs) it provides information on the available types of PPE and their field of application (Annex II), a non-exhaustive guide list of activities and sectors of activity which may require the provision of personal protective equipment (Annex III), and a specimen risk survey table for the use of PPE (Annex I).
Comprehensive protection by use of PPE against the hazards at work requires more than proper selection based on the protection level needed: The directive 89/656/EEC (1989) requires an assessment of personal protective equipment itself, which has to consider the risks which may be introduced by use of PPE. With regard to this assessment the European Commission has published information especially for SMEs in the "Commission Communication 89/C 328/02" (Official Journal of the European Communities No. C 328). Further assistance in selection and use of hearing protectors is given in the European Standard EN 458: "Hearing protectors - Recommendations for selection, use, care and maintenance - Guidance document" (EN 458:1993). In Germany more detailed information is available at www.hvbg.de/bgvr :The publication "BGR 194" (Rules for the application of hearing protectors, 1998) can be found here in German. In addition a PC-selection program for hearing protectors in German (Personal protective equipment - Selection program) is provided at www.hvbg.de/d/bia/fac/softwa/psasw/index.html
Some obligations of the employer
In section II, Article 4 of the European Directive 89/656/EEC (Official Journal of the European Communities L 393, 30/12/1989 p. 0018 - 00281) is specified:
1. ...
All personal protective equipment must:
(a) be appropriate for the risks involved, without itself leading to any increased risk;
(b) correspond to existing conditions at the workplace;
(c) take account of ergonomic requirements and the worker's state of health;
(d) fit the wearer correctly after any necessary adjustment.
2. Where the presence of more than one risk makes it necessary for a worker to wear simultaneously more than one item of personal protective equipment, such equipment must be compatible and continue to be effective against the risk or risks in question. ...
Within the selection of PPE by the employer the legal base for consideration of risks introduced by use of PPE is given by the national transposition into national regulation by the EU member states of requirement (a) shown above. The same applies to the selection of more than one PPE to be worn simultaneously (s."2."above).
In addition information and training of the users referred to appropriate use and maintenance of PPE is regarded to be very important by the directive 89/656/EEC (Official Journal of the European Communities L 393, 30/12/1989 p. 0018 - 00281). In practice this turned out to be very important for the acceptance of PPE's application by the employees. Therefore the European Directive 89/656/EEC (Official Journal of the European Communities L 393, 30/12/1989 p. 0018 - 00281) specifies in section II, Article 4:
7. The employer shall first inform the worker of the risks against which the wearing of the personal protective equipment protects him. 8. The employer shall arrange for training and shall, if appropriate, organise demonstrations in the wearing of personal protective equipment.
Assessment of PPE by the employer
In section II, article 5 of European Directive 89/656/EEC (Official Journal of the European Communities L 393, 30/12/1989 p. 0018 - 0028) it is described which requirements have to be fulfilled by the assessment of the PPE to be carried out by the employer:
1. Before choosing personal protective equipment, the employer is required to assess whether the personal protective equipment he intends to use satisfies the requirements of Article 4 (1) and (2).
This assessment shall involve:
(a) an analysis and assessment of risks which cannot be avoided by other means;
(b) the definition of the characteristics which personal protective equipment must have in order to be effective against the risks referred to in (a), taking into account any risks which this equipment itself may create;
(c) comparison of the characteristics of the personal protective equipment available with the characteristics referred to in (b).
This assessment may result in the situation that the employer recognizes that the PPE which he intends to use is not appropriate because it does not satisfy the requirements of Article 4 (1) and (2). E.g. new risks may be introduced by use of that PPE which cannot be accepted.
Solution for situation described in the introduction
In the situation described in the introduction (an employee maintaining the equipment of a large plant in steel industry who uses a hand-held grinding machine) considering section II, Article 4 and 5 of the PPE user directive (Official Journal of the European Communities L 393, 30/12/1989 p. 0018 - 0028), and especially article 4, para 2, the solution may be: Use of a helmet mounted ear muff in combination with a protective goggles equipped with textile bands replacing the earpieces or helmet mounted ear muff with visor.
Risks arising from (the use of) the equipment
In the "Commission communication for the implementation of Council Directive 89/656/EEC of 30 November 1989, concerning the assessment of the safety aspects of personal protective equipment with a view to the choice and use thereof (89/C 328/02)" (Official Journal of the European Communities No. C 328 on 30 December 1989, p. 3-14) for each type of PPE "THE RISK TO BE COVERED", the "RISKS ARISING FROM THE EQUIPMENT", and "RISK ARISING FROM THE USE OF THE EQUIPMENT" are listed.
Risks to be covered:
For hearing protection it is specified that for the risk of continuous noise and impulse noise within the selection of the protector a sufficient noise reduction for all types of noise is required. To consider metal splashing, for example during welding, the hearing protector selected has to resist molten or burning materials as tested within the EC-type examination by the notified body.
Risks arising from the equipment:
The risk of discomfort and interference with work caused by inadequate comfort such as 'too bulky', too much pressure', 'increased perspiration', and 'inadequate grip' is considered by selection of hearing protectors providing appropriate ergonomic design referred to 'bulk', 'pressure when worn and effort required to keep in place', and 'adaptability to individual requirements'.
The risk of restriction of hearing capacity caused by deterioration of ability to understand words, recognize signals and key sounds during work requires to select hearing protectors showing an appropriate performance referred to the attenuation provided in the frequency bands relevant and may require audio tests before selection or the use of suitable electro-acoustic protection. Necessity of location of noise sources gives preference to use of ear plugs instead of ear muffs.
Within the selection of hearing protectors consideration of
- quality of materials,
- ease of maintenance,
- possibility of replacing ear muffs by use of disposable ear plugs,
- rounded edges and corners,
- elimination of elements which pull hair,
- resistance to combustion and melting and
- non-flammability, resistance to flame avoids the risks of accidents and health hazards caused by
- poor compatibility,
- poor hygiene,
- unsuitable materials(ECTE)
- sharp edges (ECTE),
- pulling hair,
- contact with burning objects (ECTE) and
- contact with flame (ECTE).
"ECTE": Considered during EC-type examination. The risk of ageing caused by exposure to weather, ambient conditions, cleaning and use can be considered within the selection of protection by taking care to resistance to industrial wear and tear and maintenance of characteristics throughout useful life.
Risks arising from the use of the equipment:
The risk of inadequate protection caused by
- wrong choice of equipment,
- incorrect use or
- dirty, worn or deteriorated equipment requires to take care within the selection and use of hearing protectors to
- selection of equipment in line with nature and scale of risks (e.g. rating level at workplace) and stress (e.g. use on construction sites or clean room) and to suit user's individual requirements (e.g. special shape of ear canals),
- appropriate use of equipment being aware of risks (e.g. worker information and training),
- following the manufacturer's instructions,
- maintain the protector in good condition,
- carrying out regular checks,
- and replacement in good time (e.g. cushions of ear muffs).
Selection of Hearing Protectors
When selecting hearing protectors the following items have to be considered (s. EN 458 (Hearing protectors; Recommendations for selection, use, care and maintenance; Guidance document):
- Working environment and activity
- Sound attenuation requirement
- Wearing comfort
- Compatibility with other headgear
- Medical disorders
- Existing hearing impairment
Risk of inadequate protection by having no correct consideration to the working environment and activity:
[Figure - 1] shows an example for inadequate protection: When an ear-muff is worn in a hot environment, users might regularly remove the ear-muffs to wipe the sweat from their outer ears. If the ear-muffs are removed for only one minute every half hour, the wearing time is 97 % but the effective exposure to noise is increased by more than 10 dB! Dependent on the sound pressure level outside, the ear-muffs and the long-term exposure (over several years) the risk of deterioration of hearing could be increased up to nine times (according to ISO 1999 (ISO 1999,1990). In such a hot environment the solution may be to use ear-plugs.
Regular short-term removal of the hearing protector within noise zones may be very dangerous for hearing! Other things relating to the working environment and activity can cause regular short-term removal, i.e. humidity, informative sounds of the working process, warning signals, speech communication and localization of noise sources.
Risk of hearing _ capacity reduction by distortion of sound transmitted:
The last four items are very important if the risk of accidents is increased by wearing a specific hearing protector. This may happen because of a change of the user's sound perception caused by the specific hearing protector so that the informative sounds are not recognized by the user. A hearing protector with a more suitable performance should be selected (s. below).
Ear-muffs effect the localization of sound sources because the diffraction of the incoming sound by the pinna is changed and therefore the localization in the vertical plane decreased. In such situations ear-plugs perform better.
The ability to hear the fire-alarm or alarms of similar importance by all employees has to be guaranteed and in case of any doubt a hearing check according to EN 457 (1992) should be carried out.
Risk of inadequate protection by disregard the sound attenuation requirement:
To select hearing protectors according to their sound attenuation the A-weighted equivalent continuous sound pressure level at the workplace has to be determined. EN 458 (1993) describes four different methods to determine suitable hearing protectors.
If a hearing protector has the correct sound attenuation, the equivalent sound pressure level at the users hearing has to be between '(national) action level minus 15 dB(A)' and '(national) action level' (according to EN 458, 1993). Under-protection will create or increase the risk of hearing impairment. Over-protection may lead to a sense of isolation and difficulty perceiving sounds; this will cause the user to remove the hearing protector to increase perception of sounds in certain situations.
As a comparison: Sunglasses are selected according to their price, comfort, design, and effectiveness. Nobody would use a welding goggles while driving their car because the ratio efficiency/price is very high. For safety at work users of hearing protectors need a certain amount of acoustic information from their working environment!
Risk of health hazards by incompatibility with other headgear:
The side arms of spectacles or the retaining harness of a respirator could disturb the seal of an ear-muff against the head and can reduce sound attenuation. In such cases ear-plugs would be preferable.
Risk of inadequate protection by poor fitting Poor fitting of hearing protectors can have a large effect on the obtained sound attenuation: Within a German study differences in the mean of about 13 dB for foam ear-plugs, about 6 to 9 dB for cotton-wool plugs and about 4.5 dB for ear-muffs were found (Pfeiffer,B.H., 1989). But in all cases several employees obtained a sound attenuation at their workplaces found in the laboratory. Employees need advice and training in the use of their hearing protection to achieve the expected protection.
Risk of health hazards by use of communication devices at noisy workplaces: As an example for the total noise exposure when communication devices are worn in noise zones the results of measurements carried out by BIA at a helicopter pilot work environment are presented (Liedtke, M., 2001): The sound level of the ambient noise for the pilot in the cockpit of a helicopter was 96 dB(A). The pilot's communication headset had an attenuation of 15 dB(A) for the cockpit sound. That resulted in a remaining component of the cockpit sound effective to the pilot's hearing of 81 dB(A). For the second sound component, which was generated by the communication aspect of the hearing protector, 86 dB(A) was determined. The total sound exposure of the pilot was 87 dB(A). By this simple example it can be shown, that for the assessment of the risk of hearing impairment the total sound exposure has to be determined: the sound attenuation of the headset was sufficient for the cockpit noise and the remaining sound component did not exceed the action value of 85 dB(A). But the pilot was actually exposed to 87 dB(A) and the action value of 85 dB(A) was exceeded.
Experts' recommendations for safe design of communication hearing protectors
To realize proper selection and safe use of communication hearing protectors it is important for the users to know the principles for their safe design. All hearing protectors have to fulfil the same requirements as specified for conventional hearing protectors. For communication ear muffs an agreement was found by the European experts: Communication hearing protectors for entertainment purposes, such as ear muffs with built-in broadcast receivers, must have a sound level limiter to keep the total noise exposure below 85 dB(A) provided that the passive attenuation is sufficient for the noise at the workplace. If a communication hearing protector is not used for entertainment it should also have a limiter for normal applications. The safe operation of the limiter has to be tested by an independent testing body (in Europe: notified body).
In exceptional cases, where non-perception or misunderstanding of communication at noisy workplaces results in a significant risk of accidents, the sound level limiter is allowed to limit at levels above 85 dB(A) total noise exposure. Such an exceptional case are is for example the headsets of helicopter pilots and crew members of sea rescue services. Using information on the maximum allowed operation time at maximum volume per work shift the user can exclude the risk of hearing impairment in these exceptional cases. If manufacturers produce communication hearing protectors without sound level limiters, they have to achieve the safe use of their products by other measures to avoid the risk of hearing impairment, i.e. by giving corresponding instructions for use.
Details on acoustic perception while wearing hearing protectors
Acoustic perception of the environment is much more important for orientation than people realize. Whereas our eyes can only observe the area in front of the head, the ears recognize sound from all directions. Users maintain that hearing protectors may impede or prevent acoustic perception - for example, a forklift truck's acoustic warning signal from behind the user.
And in fact hearing protectors can decrease perception of acoustic warning signals and speech intelligibility because the majority of them change the spectral composition of the sound transmitted. Therefore, in areas where signal audibility, speech intelligibility or perception of informative operating sound is important, only hearing protectors with a suitable attenuation value and frequency curve should be used.
In cases where perception of the abovementioned sounds may be impaired, EN 458 (1993) recommends giving preference to "hearing protectors having a uniform sound attenuation characteristic over the frequency range".
But what does this mean in terms of good signal audibility, speech intelligibility and perception of informative operating sound?
For hearing protectors to be used in railway systems and road traffic in Germany well established criteria were laid down by bodies responsible (Liedtke, M., 1998): only hearing protectors that do not significantly impair the audibility of acoustic warning signals should be used. They have to be pre-selected by special calculations carried out at the BIA applying the criteria mentioned above. In addition they have to be verified by a listening test under operating conditions at the workplace concerned. For those to be worn in road traffic in Germany a certificate has to be issued to be presented during police checks. Wittmann et al. showed (Liedtke, M., 1998), that EN 457 and ISO 7731 (2001) is not a suitable method to estimate the signal audibility in railway networks, with regard to safety.
Criteria for hearing protectors with good signal and speech audibility in general
To find a simple criterion for selection of hearing protectors which perform well with regard to "signal audibility (general)", "speech intelligibility", and "perception of informative operating sound" the BIA explored several options using the BIA's European hearing protector database. The aims were:
- hearing protectors selected should have an obvious "uniform sound attenuation characteristic over the frequency range " as recommended in EN 458 (31993), and
- hearing protectors which were selected in Germany for railway systems and for workers driving vehicles in road traffic should fulfill the criteria for "signal audibility (general)", "speech intelligibility", and "perception of informative operating sound".
The criterion which best fulfils these two requirements is as follows (Liedtke, M., 2002): If the gradient of the linear regression of mean values of attenuation (obtained according to ISO 4869-1, 1990) for 125 Hz up to 4000 Hz is smaller than 3.60 dB per octave the hearing protector is suitable in terms of "signal audibility (general)", "speech intelligibility", and "perception of informative operating sound"[10].
For everyday use a PC program for selection of hearing protectors (in German) based on EN 458 (1993) using the criteria mentioned above is available at http://www.hvbg.de/d/bia/fac/softwa/psasw /index.html
| References | | |
| 1. | Council Directive 89/656/EEC of 30 November 1989 on the minimum health and safety requirements for the use by workers of personal protective equipment at the workplace (third individual directive within the meaning of Article 16 (1) of Directive 89/391/EEC), Official Journal of the European Communities L 393, 30/12/1989 p. 0018 - 0028 *  |
| 2. | EN 457 (1992) Safety of machinery; Auditory danger signals; General requirements, design and testing |
| 3. | ISO 7731 (2001) Ergonomics - Danger signals for public and work areas - Auditory danger signals |
| 4. | ISO 1999 (1990), Acoustics - Determination of occupational noise exposure and estimation of noise induced hearing impairment |
| 5. | ISO 4869-1 (1990) Acoustics; Hearing protectors; Subjective method for measurement of sound attenuation |
| 6. | Liedtke, M., (2002) Specifying a general criterion for hearing protectors with the aim of ensuring good acoustic perception, Noise & Vibration Worldwide 33 July 2002, pp. 19-23, Multi-Science Publishing Co Ltd, Brentwood, Essex, UK |
| 7. | Liedtke, M., (2001) Determination of sound immission from sources placed close to the ears - such aus head- and earphones, International Congress and Exhibition on Noise Control Engineering, The Hague, The Netherlands, August 27-30 |
| 8. | Liedtke, M., (1998) Selection of hearing protectors to be used in noise areas in road traffic or railway systems in Germany, Advances in Noise Research, Protection Against Noise, Volume II, pp. 177-182, Edited by Deepak Prasher, Linda Luxon and Ilmari Pyykko. Whurr Publisher London 1998 |
| 9. | Pfeiffer,B.H., (1989) Schalldammung von Gehorschiitzern in der betrieblichen Praxis, BIA-Report 5/89, Berufsgenossenschaftliches Institut fir Arbeitssicherheit - BIA des Hauptverbandes der gewerblichen Berufsgenossenschaften, Sankt Augustin |
| 10. | Rules for the application of hearing protectors (in German), BGR 194, Cologne: Carl Heymanns Verlag 1998** * available via internet at http://europa.eu.int/eur-lex ** available via internet at http://www.hvbg.de/bgvr |
Correspondence Address:
M Liedtke
Berufsgenossenschaftliches Institut für Arbeitsschutz - BGIA, Alte Heerstrasse 111, D-53754 Sankt Augustin
Germany
 Source of Support: None, Conflict of Interest: None  | Check |
PMID: 16053603 
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