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Ear Protection

Published: 10th Jun 2010 in OSA Magazine

 

In noisy workplaces hearing must be protected with hearing protectors. Often the results are poor, however, which makes the ear protection a bad investment. The key to successful ear protection is the careful planning and deep understanding of things that can go wrong. Failing to do so means the numbers suffering hearing loss will ?not decrease.

In safety management protectors are often the last priority. First one should try to reduce the sound exposure by controlling the source, or by reducing the exposure time by organising the work in a different way. These technical measures take a long time, often several years. Taking the hearing protectors in use is a relatively fast process. In addition, the technical means are not always possible and thus the hearing protectors are the only way to reduce the exposure. 

In several studies it has been found that the attenuation of hearing protectors is worse than predicted by laboratory tests (Figure 1). In addition, the usage rates of hearing protectors are far from 100%, which is required for good protection (Figure 2).

Several explanations have been attributed to these phenomena. One explanation is related to the poor motivation of the workers. The hearing protectors are seen as a nuisance because the risk of hearing loss is felt to be minimal. For noise-induced hearing loss an exposure time of more than 30 years is needed in typical cases. Often the hearing protectors are not used because of fear not to hear warning signals, reduced speech intelligibility or difficulties in localisation of moving machines. One of the major reasons for removing hearing protectors in noise is conversation with fellow workers. Last but not for not using hearing protection is skin irritation. At worst this may lead to ear canal infection when dirty plugs are inserted to the ear.

The sense of isolation is a crucial factor. Sometimes in the factories you can see solutions to overcome this situation. People bore a hole in earplugs or they shorten them (Figure. 3). With earmuffs solutions to increase the leakage can also be found. These solutions may lead to serious under protection and naturally the attenuation is not predictable anymore.

To overcome these problems, serious planning of ear protection is needed. The new European noise directive provides a good checklist for things to consider when planning ear protection:

The availability of hearing protectors with adequate attenuation characteristics (Article 4.6 j)

If the risks arising from exposure to noise cannot be prevented by other means, appropriate, properly fitting individual hearing protectors shall be made available to workers and used by them in accordance with the provisions of Council Directive 89/656/EEC (Article 6.1)

The employer shall make every effort to ensure the wearing of hearing protectors and shall be responsible for checking the effectiveness (Article 6.2)

Workers have to have information about the correct use of hearing protectors (Article 8 e)

The worker must be consulted and participate in the choice of individual hearing protectors (Article 9)

In exceptional situations where, because of the nature of the work, the full and proper use of individual hearing protectors would be likely to cause greater risk to health or safety than not using such protectors, the use of hearing protectors can be omitted

Let us look closer at these above cited points:

Selecting hearing protectors

Selection of hearing protectors with adequate attenuation characteristics 

The directive requires adequate attenuation characteristics form the hearing protector, but does not define what this means. Based on the exposure limit values, it can be stated that the directive sets implicitly the noise exposure level under the hearing protector to be less than 80 dB(A) when possible. This can be checked either by evaluating the noise level using the methods given in standard EN 458 or by measuring the level using the standard ISO 11904. On the other hand, if the attenuation is too high, it leads to overprotection and results in poor usage rates. Thus the exposure level should not be too much under 80 dB(A).

The descriptor “adequate” sets additional demands. As stated above, the users tend to remove the hearing protectors while having a conversation. Thus in work places where it is possible to communicate, the hearing protectors must be selected in such a way that they maintain the speech intelligibility. This is especially important when the communication need is related to the work tasks. To solve the communication needs, electronic hearing protectors or protectors with constant attenuation are solutions to consider. In the music and entertainment sector the constant attenuation is the best solution.

The employer shall make every effort to ensure the wearing of hearing protectors   

The nominal attenuation, given by the manufacturers, varies from 15 dB to 35 dB, depending on the hearing protector and the frequency contents of the noise. This nominal attenuation rating is obtained only if the usage rate is more than 99% of the exposure time, and if the condition of the hearing protector is good. 

Figure 1 shows that it is possible to obtain good attenuation close to the attenuation values given by the laboratory test. This requires proper installation of the protector which is in good condition, and the user should be highly motivated. This is why our next topic - the worker information - is so important. Also, training sessions in installing hearing protectors has proven to be beneficial.

Worker information about the correct use of hearing protectors   

Low motivation to wear the hearing protector is seen as low usage rates and low true attenuation values. A successful motivation can be obtained through appropriate education and training. The users must also be informed about the effects of noise and the risks at work. Best results are obtained if personal audiometric data is used. This means that the education must be given personally. Users need training on maintenance, installation and use of the protectors, otherwise the attenuation may be poor. Good maintenance consists of cleaning, changing of replaceable parts like cushions and overall monitoring of the state of the protector. Installation must be done before entering the noisy area if earplugs are used, and special attention to the proper installation technique must be paid.

Although it is possible to inspire highly motivated users with proper education and training, the motivation tends to decrease over time. To avoid this, the education and training must be repeated consistently.

It takes long periods (5-15 years) to change the safety culture in such a way that people will always use the hearing protectors (Figure 2). In spite of all efforts the usage rate may still stay low, like for paper industry workers in Figure 2. One simple solution would be to force the usage. However this is not a recommended solution because workers tend to develop solutions which cancel the effect of hearing protectors. For a good solution training and selection of hearing protectors which minimise the drawbacks of the protectors is needed.

Consultation and participation of workers in the choice of individual hearing protectors   

The attenuation of hearing protectors depends on the individual worker. The given attenuation values are obtained by 84% of the users. Thus 16% of the users get worse attenuation than predicted. In addition, there may be restrictions which disable completely the usage of the selected hearing protector. Factors that may limit the usage of plugs include:

Narrow or wide ear canals

Repeated ear canal infections

Sense of pressure in the ears

Sense of dizziness

Hesitancy to insert things into the ear

For earmuffs the limiting factors ?consist of:

Skin irritation

Weight

To overcome these problems the standard EN 458 recommends that the workers are allowed to select between two or three different models with appropriate attenuation characteristics.

However, the need for communication is not taken care of by these recommendations.

The exceptional situations when the full and proper use of individual hearing protectors would cause greater risk to health or safety than not using such protectors   

Hearing protectors hamper the communication and hearing of warning signals, especially for workers with a hearing impairment. This can lead to increased risk of accident. Also, accident reports in Finland have mentioned that listening to hearing protectors equipped with radio may have contributed to an accident. In Germany there are recommendations for use of hearing protectors in traffic because of the accident risk. In several cases the use of hearing protectors has been suspected of contributing to lethal accidents in the railroad yards. The primary cause has been a wrong action when the train was approaching. This has been addressed to reduced capability to localise the sound source. Hearing protectors are known to reduce the capability to localise sound sources especially for workers with a hearing handicap. To exclude these kind of accidents, requirements for the hearing of railroad yard workers have been set in Finland. The increased accident risk for workers with hearing difficulties has been observed in other countries, too, such as Canada and the Netherlands.

However this does not mean that a worker with hearing problems should not use hearing protectors in risky environments. It simply means that the ear protection for workers must be planned with extra care. One solution to consider is the level dependent hearing protectors. Non-auditory warning signals may also be a solution. Bearing in mind that in workplaces 10-30% of workers have a hearing impairment, it is a wise strategy to design the hearing protectors from the point of view of these workers. 

A second type of accident is related to hearing protectors equipped with radio. Accident reports suggest that listening to an exciting programme with a hearing protector that has broadband radio has contributed to accidents. That said, the radio equipped hearing protectors may be a good way to motivate the users.

Summary

Ear protection is about more than just giving hearing protectors to the workers. All protectors have their drawbacks which must be minimised in the selection process, otherwise the usage rate or protection efficiency will be low. Factors that must be taken into consideration in the selection of hearing protectors include comfort, communication needs and the needs to hear warning signals. These factors must be evaluated with special care for workers with hearing disabilities, otherwise the accident risk may increase.

Best results are obtained in co-operation with the employer, occupational health care and exposed workers. Before starting the selection process the workers have to be informed about the noise risks and the factors affecting the usability of hearing protectors. 

A well planned ear protection policy minimises the adverse effects of noise. This is seen as improved quality in the production. ?

References

2003/10/EC, DIRECTIVE 2003/10/EC ?OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 6 February 2003 ?on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (noise)

Girard, M Picard, M Simard, R Larocque, ?F Turcotte, A Simpson and S Roy, Work-related accidents associated with noise-induced hearing loss and noisy workplace, 7th World Conference on Injury Prevention and Safety Promotion, 2004

Merry C J, Sizemore CW, Franks JR. (1992). The Effect of Fitting Procedure on Hearing Protector Attenuation, Ear and hearing 13(1)11-18

Moll Van Charante AW and Mulder PGH. Perceptual acuity and the risk of industrial accidents. American Journal of Epidemiology 1990; 131:652-663

Morata TC, Themann CL, Randolph RF, Verbsky BL, Byrne DC, Reeves ER., Working in noise with a hearing loss: perceptions from workers, supervisors, and hearing conservation program managers. Ear Hear. 2005 Dec;26(6):529-45

Toppila E, Pyykkö I, Starck J, The use ?of hearing protectors among forest, shipyard and paper mill workers in Finland - a longitudinal study. Noise and Health, 2005;7(26):3-9

Author Details:

Esko Toppila, Anna Ruhala, Rauno Pääkkönen, Helena Mäkinen

Finnish Institute of Occupational Health, FIOH, is a research and specialist organisation in the field of occupational health and safety.

Our strategic goals are:

The management of occupational health hazards at work as part of management practices and corporate risk management

Innovative, regenerative and healthy work communities

Each citizen equipped to ensure his or her occupational safety, health and well-being

Providing authorities with information for promoting occupational health and safety

Smoothly flowing work processes, safe and easy to use working methods and tools

Solutions for increasing participation in work life

Controlling new occupational hazards, exploiting new opportunities

Address: Topeliuksenkatu 41 a A, FI-00250 Helsinki

Tel: +358-30-4741?

Web: http://www.ttl.fi

Published: 10th Jun 2010 in OSA Magazine

Author


FIOH (Finnish Institute of Occupational Health)


Author details: Esko Toppila, Anna Ruhala, Rauno Pääkkönen, Helena Mäkinen

The Finnish Institute of Occupational Health, FIOH, is a research and specialist organisation in the field of occupational health and safety.

Our strategic goals are:

  • The management of occupational health hazards at work as part of management practices and corporate risk management
  • Innovative, regenerative and healthy work communities
  • Each citizen equipped to ensure his or her occupational safety, health and well-being
  • Providing authorities with information for promoting occupational health and safety
  • Smoothly flowing work processes, safe and easy to use working methods and tools
  • Solutions for increasing participation in work life
  • Controlling new occupational hazards, exploiting new opportunities

Topeliuksenkatu 41 a A, FI-00250 Helsinki 


FIOH (Finnish Institute of Occupational Health)

Website:
http://

Phone:
+358-30-4741



http://
+358-30-4741


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