[Rischi lavorativi in ambiente sanitario]




     

Noise


INTERVENTIONS ON THE SOURCE

Elimination or replacement with more soundless machinery;
Modifications to reduce their noisiness;
Removal.


INTERVENTIONS ON THE PROPAGATION

  • Vibration suppressing supports for noise transmitted through solids;
  • Complete and partial covering, barriers and screens, silencers for direct noise;
  • Sound absorbent treatment for reflected noise

INTERVENTIONS ON THE WORKER

  • Isolation in silent cabins;
  • Personal protective devices.

PERSONAL PROTECTIVE DEVICES AND CHOICE CRITERIA
Noise protective devices can be classified into three categories: earplugs, headsets, protection noise helmets.

  • multiuse earplugs (made of rubber, soft plastic matter, expanded polymer) that can reduce the sound energy of 15-20 dB.

The disadvantages for the worker include both the difficulty in finding the precise size and the difficulty in keeping such devices clean.

  • throwaway earplugs, that can reduce the sound energy of 10-20 dB. In this case, it is possible that some fragments of insert remain in the auditory canal and this represents the disadvantage of such devices.
  • earmuffs, (made of two cups built with hard plastic material lined with expanded polyurethane and fixed with a metal elastic small arch passing either over the top of the head or behind the nucha or even underneath the chin). They can reduce the sound energy of 20-40 dB.
    In order to be effective they must have a certain weight and perfectly adhere to the periauricular skin. Furthermore, they cannot be used for 8 consecutive hours because they warm the auricle of the ear.
  • helmets, (made of different materials) are used to protect the whole head and not only the ears. They are usually supplied with a two-way radio communications unit to allow verbal communication. They provide a global attenuation of up to 50 dB. They are only worn for short periods because they are extremely uncomfortable and cumbersome.

Inserts are usually better tolerated and can be worn for the whole working period.
Helmets and earmuffs are useful in the case of short exposure (maximum two hours) to high levels of noise.
The choice of the auditory protective device is addressed by the level of environmental noisiness and determined both by the auditory condition of the worker and by his/her task. The delivery of the device is personal and is carried out both by taking into consideration the indications of the health personnel and by leaving to the worker a margin of choice among protective devices with similar characteristics.

The Italian law 277/91
This law does not define any single limit of exposure, but various levels (LEP 80, 85, 90 dBA) that, if exceeded, require the implementation of protective actions.

Below the 80 dBA threshold:

  • it is compulsory for the competent doctor to proceed to the non-instrumental evaluation of the auditory capacity of the worker exposed to noise (whispered atonic words).

Above the 80 dBA threshold (81-85 dBA):

  • the evaluation must be completed by instrumental measurements of noise;
  • it is compulsory for the competent doctor to inform workers of the auditory risks, the reduction of noise and protection measures, the personal protective devices, the health checks and the results of the carried out evaluation;
  • the health inspection should be provided for.

Workers may request the health inspection, whose appropriateness must be confirmed by the competent doctor.

Above the 85 dBA threshold (86-90 dBA), in addition to the previous point:

training is implemented about:

  • the correct employment of the personal protective devices,
  • the employment of noisy machinery;

Personal protective devices appropriate for each worker and his/her task must be provided; Health inspections are carried out

  • at the time of appointment,
  • one year after the appointment,
  • afterwards, at least every two years.

If the threshold of 90 dBA is exceeded, in addition to the mentioned points, the following must be implemented:

  • workers must comply with the employment of personal protective devices;
  • health inspections must be carried out at least yearly;
  • the situation is reported to the competent control body;
  • the concerned areas are pointed out with signs and, if necessary, supplied with boundaries to limit access;
  • a register of the workers exposed to noise is set up.

 

 

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