Preventive measures

Hearing loss from noise can be prevented. This is important, because once a hearing loss has occurred, it cannot be reversed. Information about the exposure by a risk assessment is important, followed by necessary actions to prevent negative health effects from the noise. Noise exposure at work can be reduced by several methods.

Noise reduction at the source

• Proper maintenance of machines, equipment and workplace. Lack of maintenance often results in more noise being produced by the machines and Equipment, as wear induces slackening. • Replacement of old equipment with new and/or improved.

Noise reduction by interruption of the transmission route

• Encapsulation of machines/ work processes. Engines or very noisy work processes can be placed/ performed inside a separate room or covered with noise-cancelling materials to reduce the exposure to the workplace.

Noise reduction by protection

• Change in working routines. Making sure that no one works only with the noisiest process is important; the workers can rotate on tasks thereby reducing the exposure for any given individual.
• Personal protective equipment such as ear-plugs and ear-muffs. Ear-plugs and ear-muffs can lower noise exposure, especially if the exposure is high-frequency. It is important to give the workers education in how they should wear these protective devices since the incorrect use reduces the protection markedly. Also the plugs and muffs need to routinely be changed due to wear.

Personal protective equipment

Personal protective equipment such as ear-plugs and ear-muffs are the most important acute preventive devices for protecting against noise. It’s important to know how these function, how to evaluate these and how to choose which ones to use as there are many different types on the market.

2Hørselsvern_COLOURBOX.jpg Ear plugs and ear muffs can protect our hearing ability during noise exposure. © Colourbox

Ear-plugs are small devices to be inserted in the ear canal to block it. They are often made of different types of foam, and the most widely used ear plug is shown in the picture above. Ear plugs can be marvelous hearing protective devices (HPD) if they are used correctly, but they can also be useless, and even damaging if used incorrectly.

Information – hearing conservation programs

All workplaces with high noise levels need to have strict regulations and requirements and these need to be made evident for the workers. Such workplaces should have a hearing conservation program protecting the workers. The program must be adapted to the specific workplace, but among the important aspects are:

  1. Risk assessment including:
    a. The exposures must be quantified with measurements in all relevant areas, and if a work procedure is changed or new equipment is bought new measurements or evaluations must be undertaken.
    b. All workers must be examined with a relevant clinical examination and hearing test at employment and regularly onwards depending on the recommendations made in the risk assessment and taking into account individual variations in thresholds for injuries.

  2. Plan for improvement:
    A plan for improvement, with defined responsibilities and a time-frame for actions is needed.

  3. The company/workplace must disseminate information and education on noise and hearing:
    When improvements are implemented at a work place, it is necessary to inform the workers involved about the cause of these changes. Also, it is important to note that workers need training in use of new instruments and work routines. If protective equipment will be provided, the workers need regular training in how and why this equipment should be used.

Laws and regulations

Many governments have produced their own national guidelines, but they are often based on internationally agreed guidelines. WHO has a publication named “Occupational noise levels: evaluation, prevention and control” upon which many national guidelines are based. This publication states the exposure criteria, occupational exposure levels and states that for continuous noise levels they recommend a limit of 85 dB(A). This level was chosen because it will Ensure the protection of the median of the population against noise-induced hearing loss after 40 years of occupational exposure at this level. They also discuss impulse noise and the limit is here set to 140 dB(A), but this varies nationally, due to differing opinions concerning the effects of number of impulse noise incidents, duration of these and so on.

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Occupational Health in Developing Countries

University of Bergen