NOISE AT WORK

LABOUR EXPOSITION                          THIS TEXT IS BASED IN THE Jose Mª Castañares Gandía´s Blog.

Between the amount of labour´s risk whom the workers are exposed, the noise is one of the most frequently, however it is the least being afraid of.

Maybe the lack of information plays an important role in it, but, on the other hand, the professional deafness, is apparently that one which inside the group of the professional illnesses, it is the “least hear” how it has been said. However, we are conscious of that most of a quarter of the working population is exposed to the harmful effects of the noise.

It seems like that the noise has been included to the professional environment like something “normal”, or something that it could be considered like “usual” and it is expected to get used to it, while it is hurting you day to day during your working activities. Nowadays it is being fought for a dignify salary, for a better quality of life, however this is continuously hurt by a continuously decrease of our health.

The noise is the cause of different extra auditory injuries too, as we will see next, that they are considered as injuries which have been come from the work. On the other hand, it shouldn´t be either dismissed in the studying of anyone job, that even being under the limits that are allowed by the law, it is an inadaptability cause, unease or tiredness at work. As a consequence, it would be handled from the objective of the ergonomics (acoustic comfort).

THE NOISE AND THE INDUSTRIAL HYGIENE

The sound is the vibration of a natural source (generally the air) susceptible to be guessed by the ear, and it spreads in a pressure waves way, which look like the waves that are made on the water when a stone is thrown in it.

The noise is usually defined as an annoying or no wished sound.

The sounds, at the industrial means, are complex instead of pure, they get together with impulsive sounds which stand above the background noise, causing the reverberation or the sound persistence in a close space, even after to have been stopped the sound source.

The measurement of the noise at the job environment is made through the sound level metre (scale in dB A) which values the auditory human sensation.

The levels of acoustic intensity (calculate in dB), are recorded in audible frequency bands which are measured in Herzs (Hz).

The sound level metre makes an average in the time about the different levels of noise. It measures the continues level of noise, it means, the noise whom a person is exposed during her work in a determinate time. It is called “Loud Equivalent level”.

The DOSÍMETRO measures the exposition in percentage regarding to the maximum dose that it is considerate admissible, during the workday.

 

It is important to say, that the measurement of the noise in dB follow a logarithmic scale. This piece of information, to practical effects, is interesting to know it in order to set up the prevention measures.

For example:

If a worker is exposed to the emit noise by two machines, one of them at 90 dB and the other one at 90 db, the resultant noise is not the addition of both, that is 180 db, instead of it, it will be an increase of only 2 or 3 dB above of the 90. This means that for loud levels of noise, when we are talking about one more decibel or one less, we are talking about enormous different in the noise quantity (and the injury).

For the same thing, when it is said that a protector decrease the sound level in more or less 20 dB, it should be understood that it goes from the loud hurt to the zero hurt.

Even some little reductions in the level of the decibels is fitting with a big decrease of the amount of injury.

ACOUSTIC COMFORT

Nowadays the noise is present in all of the aspects of our life, as much in private as in public life.

The noise is a sound that it is characterise by:

– Psychologically, by being annoying and unpleasant.

– Communally, by its low or non-existent informative content.

– Physically, by its spectral randomness and intensities randomness.

 

THE NOISE AND THE VERBAL COMMUNICATION

The noise can interfere in the verbal communication, well directly or by phone, until it makes it impossible.

A signal lower than 3 dB, it keeps the intelligibility at 100%

A signal of 10 dB, it reduces the intelligibility al 70%

 

INTENSITY OF THE NOISE

0 – 20 dB ………….   Hearing threshold.

20 – 50 ………….      Easy communication.

50 – 80 ………….      Possible Communication.

80 – 110 ………….    Limit Risk (day of 8 hours).

110 – 140 …………    Impossible Communication.

More than 140 ……….   PAIN.

 

TABLE OF CONVERSATIONAL MAXIMUM DISTANCES (ROBERT D. BRUCE)

LEVEL OF NOISE (dB A) LEVEL OF VOICE EFFORT

normal            loud

55 …………………    3 metros         10,5 metros

61 …………………    1,5                    5,5

69 …………………    0,6                    2,1

75 …………………    0,3                    1,2

81 …………………    0,15                  0,6

87 …………………    –                       0,3

93 …………………    –                       0,15

 

TELEPHONE COMMUNICATION IN NOISY ENVAIRONMENTS.

LEVEL OF NOISE (dB A) COMMUNCATION´S QUALITY

More than 95 dB ………………            unsatisfactory.

from 70 – 85 ……………………              difficult.

from 55 – 70 ……………………              slightly difficult.

Less than 55 ……………….                satisfactory.

 

 

THE WORK EFFECTIVENESS AND THE NOISE. 

The noise can cause a wear in:

  • Security tasks
  • Mind complex tasks
  • Task which implies ability and skills
  • Tasks which requires high levels of perception
  • Psychomotor complex tasks.

For this types of tasks, the noise supposes an overloading, and as a consequence the increase of the number of mistakes.

It supposes an increase in the possibilities of have an accident, furthermore a decrease in the performance, and a damage in the results.

PSYCHOSOMATIC ASPECTS OF THE NOISE.

It can be made the next considerations:  

At the same level, it usually be more annoying the broad band noises.

At the same sound, the high frequencies are more annoying than bass.

At the same noise, the own noises are more annoying than the others people noise.

At the same sound, the perception´s level depends on the significance.

It exists some subliminal factors in the noisy environments, which are in relation with the masked noises.

SICHOSOMATICS SYMPTON WHICH ARE ATTRIBUTED TO THE NOISE.  

The most frequents:

– asthenia (fatigue)

– irritability or tension.

– headache.

-difficulty to sleep and sleep disorder.

– blood irrigation (pallor).

– lumbago (back pain).

– digestive disorders (nausea, gastroduodenal ulcer …).

– buzzing.

– impotence.

– general pain.

 

MUSIC AT WORK

The reasons whom it is recommended to use it are different:

  • To reduce or make up for the low sensorial stimulation of the repetitive and monotonous Works.
  • To cover up the noisy environment (it should keep below than 3-5 dB)
  • With the intention to make “privacy barriers” in the conversations.

In any case, it depends on the personal and individuality situation regarding to the preferences, etc.

RELATION OF THE SOUND EXPOSITION INTENSITIVES (IN DB) DEPENDING ON THE TYPE OF ACTIVITY WHICH IS CARRYING OUT (ISO REFERENCE)

ACTIVITY- INTENSITIVE ZONE (DB)

Rooms for the night rest……………………………    10-20

Study rooms, surgery rooms, class rooms ……………….. …………………….. 20-30

Office standard rooms……….. …………………..  30-40

Big storehouse …………………………….. …………………………..40-50

small industry with manual tooling………. ………………….  50-60

industry with machines ……………………. ………………………. 60-70

large industry with important machinery……………………..    70-80

industry with risk of professional deafness…. ………………      80-90

industry with personal protection.. …………….      90-100

prohibited area except brief stays…………………..      100-110

 

NORMATIVE

Decreto 2107/1968 de 16 de agosto, sobre régimen de poblaciones con altos niveles de contaminación atmosférica o de perturbaciones por ruidos o vibraciones. (B.O.E. 3/9/1968)

Acuerdo de Ginebra (20/3/58) Reglamento sobre homologación de indicadores de dirección, luces de posición, luces rojas posteriores, luces de paro y ruidos. (B.O.E. 11/3/1970)

Decreto 1439/1972 de 25 de mayo sobre homologación de vehículos en lo que se refiere al ruido.

Norma Básica de la Edificación NBE-CA-81 sobre condiciones acústicas en los edificios.

Convenio nº148 de O.I.T. sobre el medio ambiente de trabajo (contaminación del aire, ruido y vibraciones) 1977. (Ratificado en B.O.E. 30/12/1980).

R.D. 873/1987 sobre limitación de emisiones sonoras de aeronaves subsónicas.

R.D. 245/1989 sobre límites de potencia acústica admisible de determinado material y maquinaria para construcción y cortadoras de césped.

R.D. 1316/1989, sobre protección de los trabajadores/as frente a los riesgos derivados de la exposición al ruido durante el trabajo. [Actualizado 2006]

Determinación y limitación de la potencia acústica admisible de determinado material y maquinaria de obra. (B.O.E. 11/3/1989) Modificado por O. De B.O.E. 1/12/1989, 26/7/1991)

R.D. 1256/90 sobre limitación de emisiones sonoras de aviones a reacción subsónicos civiles. (B.O.E. 18/10/1990)

Especificaciones sobre el ruido en el etiquetado de los aparatos de uso doméstico. (B.O.E. 14/3/1992)

R.D. 1422/1992 sobre limitación del uso de aviones de reacción subsónicos civiles. (B.O.E. 17/12/1992)

 

 

#acousticcomfort #withoutnoise #noiseandhealthy