DPI uditivi / Tipologie

1
The implementation of the noise directives in a
Member State Renata Sisto Department of
Occupational Hygiene Monte Porzio Catone (Roma),
ITALY r.sisto_at_dil.ispesl.it
2
SUMMARY

• Hearing loss as the first occupational disease in
  Italy
• Early effects on hearing of noise exposure
• An evaluation of current law efficacy in risk
• control
• Perspectives and outlooks

3
Noise / Hearing Loss
Industry, services and agriculture - years
19992004. (data from Italian National Institute
of Public Accident Insurance INAIL )


Notification year Hearing impairment in listed occupational fields Hearing impairment in listed occupational fields Hearing impairment in non listed occupational fields Hearing impairment in non listed occupational fields TOTAL Noise induced Hearing impairment TOTAL Noise induced Hearing impairment
N. R. N. R. N. R.
1999 5843 2015 6640 12483
2000 5379 879 6374 11753
2001 4816 549 5943 10759
2002 3641 465 3698 7339
2003 2631 357 3663 6294
2004 2178 209 3725 5903
N Notified on suspicion R recognized and
refunded
4
Noise / Hearing Loss
5
Noise / Hearing Loss
6
Noise / Hearing loss
Noise induced hearing loss is at day the first
occupational disease

• Between 1999 and 2004 the Italian National
  Institute of Public Accident Insurance (INAIL)
  recognized and refunded in industry, and services
  occupational fields about 4470 new cases of
  occupational noise induced hearing loss.
• During the years 1999-2004 the percentage
  incidence of noise induced hearing impairment
  results to be near 50 of the total number of
  notified cases of occupational disease

7
Noise / Hearing loss

• Occupational noise-induced hearing impairment is
  still a major phenomenon, even if its general
  evolution shows an important and constant
  decrease, from 12483 cases notified on suspicion
  in 1999 to 5903 cases notified on suspicion in
  2004, and from 2015 cases recognized and refunded
  in 1999 to 209 cases recognized and refunded in
  2004.

8
Aging-induced hearing loss
20 years
30 years
50 years
60 years
Hearing threshold dB
65 years
9
Noise-induced hearing loss
Exposure duration (years)
Hearing threshold dB
10
The ISO 1999 (1990) standard
The ISO 1999 standard provides the algorithms to
calculate the NIPTS (Noise Induced Permanent
Threshold Shift) at different percentiles as a
function of frequency, of personal daily exposure
level LEX, 8h and of exposure duration, in
years. The NIPTS which corresponds to the median
of the distribution (50 percentile) can be
calculated with the use of the following
formula N0,50 u v
log(q/q0)(Lex, 8h L0)2 where u, v and L0 are
functions of frequency and q is the duration in
years of the exposure
11
The ISO 1999 (1990) standard
12
The ISO 1999 1990 standard
It is the standard currently used to estimate the
dose-effect relation also by the Italian National
Institute of Public Accident Insurance (INAIL)


 The ISO standard gives the predicted hearing
threshold H, expressed in decibel, as function
of the age and of the noise exposure
H H N (HN/120) where H
is the predicted hearing threshold, in decibel,
as function of the age (HTLA) N is the noise
induced permanent threshold shift (NIPTS) The H
and N values are given in different percentile
ranges
13
Cochlear gain and feedback

• The outer hair cells (OHCs) are the heart of an
  active feedback mechanism that permits to obtain
  high sensitivity to low amplitude signals and a
  good frequency discrimination capability.
• The amplification gain associated with this
  system can be estimated of order 40 dB.
• Noise induced damage initially affects OHCs, with
  a reduction of this gain resulting in a
  corresponding increase of the hearing threshold.

14
Outer hair cells (OHCs) schematics
TM
IHCmechano-electrical transduction
OHCelectro- mechanical transduction
BM
15
Noise exposure and early hearing impairment

• Experimental data show that even in the cases in
  which there has not been observed yet a hearing
  threshold increase corresponding to the clinical
  definition of hearing impairment (threshold
  higher than 20 dB at one or more audiometric
  frequency), the hearing threshold undergoes a
  statistically significant increase in the
  populations of subjects exposed to noise.
• In the next figure a comparison is shown between
  the average hearing threshold of non exposed
  (normal) and exposed subjects. Even if for the
  exposed population there is not yet any
  clinically defined hearing loss (for the MHL
  class, 10dBltHT20dB), the degradation of the
  threshold (with the characteristic frequency
  dependence of noise induced hearing loss) is
  already visible with respect to the non exposed
  subjects of the same age.

16
Comparison of average audiometric thresholds
between a population of young (mean age30 years)
exposed (MHL, HL) and non exposed subjects
(Normal)
non exposed
exposed
exposed
17
A new diagnostic technique based on otoacoustic
emissions can be used to detect the early effects
of noise exposure
Comparison of TEOAE SNR between a population of
young (mean age30 years) exposed (MHL, HL) and
non exposed subjects
exposed
exposed
18
Noise / State of the Art
Actual evaluation and control of risk from
occupational noise exposure

• The risk evaluation reports in some productive
  fields
• are either absent or unsatisfactory from a
  qualitative point of view.
• The technical reports often lack fundamental
  information
• The level of performance of the law against noise
  implementations is not sufficient.
• In particular, the implementations relative to
  the technical, organizational and procedural
  participations are disregarded.

19
Noise / State of the Art
Actual evaluation and control of risk from
occupational noise exposure

• There is no territorial uniformity in the risk
  evaluation reports and also in the regional
  regulations
• Official statistical studies are absent relative
  to occupational noise exposure in Italy.
• A national data base is absent containing the
  personal daily exposure level in the different
  occupational fields.

20
Noise / State of the Art
Actual evaluation and control of risk from
occupational noise exposure

• According to the data communicated to Italian
  National Institute for Prevention and Safety at
  Working Places (ISPESL), the workers officially
  exposed to personal noise levels above 90dB(A)
  are 41000, and the workers exposed to levels in
  the range
• 80dB(A) lt LEX, 8h lt 90dB(A) are about 12000.
  
• These data are evidently underestimated, if one
  thinks that there are in Italy more than three
  millions of companies

21
Noise / Risk evaluation

• The risk evaluation reports in some particular
  occupational field are totally absent or they are
  insufficient from a qualitative point of view.
• Transports in many public or private transport
  companies a noise risk evaluation is still
  absent due to an incorrect interpretation of the
  Italian law.
• Schools the noise risk evaluation is totally
  absent although occurrence of hearing impairment
  pathologies is growing among the teachers.

22
Noise / Risk evaluation in schools

• ISPESL is promoting a national project research
  about
• noise risk at school. High noise levels were
  found, especially in
• maternal and elementary schools.
• The high levels of noise cause hearing impairment
  and insurgence of laryngopathologies in teaching
  staff and they cause learning difficulties and
  loss of attention in pupils.
• The high levels of noise are principally due to
  the architectural
• characteristic of scholastic buildings. For
  example
• the insufficient insulation of the classrooms
  cause high levels of disturbances produced by
  external sources
• reverberating effects from the walls produce
• sound distortion and loss of speech
  intelligibility

23
Noise / Risk evaluation in schools
Maternal school Teachers (a.m. turn) LEX,8h 85.3 1.8 dB(A) (dosimetric methodology) LEX,8h 84.3 2.9 dB(A) (phonometric methodology) Lpeak 123.5 dB
Maternal school Teachers (p.m. turn) LEX,8h 85.8 1.4 dB(A) (dosimetric methodology) LEX,8h 84.3 2.3 dB(A) (phonometric methodology) Lpeak 123.5 dB
Non teaching staff LEX,8h 80.9 1.4 dB(A) (phonometric methodology) Lpeak 110.7 dB
Nataletti P., Pieroni A. in Acustica and
Scholastic Environments. Venezia, 5 maggio, 2005
24
Noise / Technical reports

• The technical reports are often incomplete and
  not exhaustive.
• Hearing protectors it is very rare to find in
  the reports the effective degree of protection
  given by the personal protective equipments
  calculated in agreement with the standard EN 458
  (2001)

25
Hearing protectors
Attenuation is a statistical variable
characterized at each octave frequency band by a
mean value and by a standard deviation
This statistical aspect is often neglected in
technical reports so leading to an underestimate
of the actual noise exposure.
26
Gaussian probability distribution
Probability density
Attenuation (dB)
Population in the interval between m-s and ms
27
Gaussian probability distribution
Probability density
Attenuation (dB)
The mean attenuation m(f) minus 1 standard
deviation, (m-s), is the minimum attenuation for
84 of the population of exposed subjects
28
m - as
The choice a 1 is currently done without
considering that 16 of workers have an
attenuation lower than the assumed minimum value.
The attenuation data reported by manufacturers
are referred to the minimum attenuation for the
84 of the population. The italian regulations
do not sufficiently stress this statistical
aspect. Neglecting the statistical nature of the
attenuation given by hearing protectors could
produce mistakes in the risk evaluation.
29
Hearing protectors / Real attenuation
The attenuation data reported by manufacturers
are referred to the maximum attenuation
evaluated in standardized conditions. In working
places the conditions are very different 1)       
     workers are not formed to the use of hearing
protectors 2)            the wearing conditions
are not optimized 3)            the size is often
not optimized 4)            there are
anthropometric differences in the external ear
5)            the hearing protectors have to be
worn for a long time 6)            there are
uncontrolled movements (mandibular,
etc.) 7)            the wearing conditions are
affected by physical activity 8)           
discomfort ? The attenuation of hearing
protectors in working places are lower than those
declared by manufacturer
30
Hearing protectors / Real attenuation
Work enviroment(min) Work enviroment(max) Declar
ed by manufacturer
Frequency (Hz)
Muffle Mean attenuations and their standard
deviations declared by manufacturer compared to
those measured in a real work environment
31
Hearing protectors / Formation effect
No instructions With instructions Practical
demonstration Declared by manufacturer
No instructions With instructions Practical
demonstration Declared by manufacturer
32
Risk evaluation in call centers
Call centers This is a case in which the
methodology given by the current law to perform
risk assessment is totally inadequate. The
incorrect risk evaluation standard methodology
(phonometric measurements with a microphone at 10
cm from the ear) causes an underestimate of
exposure levels, and consequently, an
insufficient level of protection. The solution
is a new methodology based on an artificial
manikin and/or a miniaturized microphone inserted
into the ear canal. The first methodology is
being standardized in Italy.
33
Methodology and instrumentation for the inside
and outside evaluation of noise

• Manikin method (ISO/DIS 11904-2 (2000).
  Acoustics - Determination of sound immissions
  from sound sources placed close to the ears -
  Part 2 Technique using a manikin
  (manikin-technique) )
• 1. Noise is measured at tympanic height with the
  manikin microphones
• 2. A correction is performed using the transfer
  function (provided by the manufacturer, by the
  ISO 11904-2 or experimental)
• 3. Elaboration of the recorded spectrum provides
  an estimate of the noise outside the ear that
  would produce inside it the measured noise

34
Manikin used for the measurements
Manikin BK 4128 Right Ear BK 4158 Left
Ear BK 4159 Outer Ear BK DZ 9752
35
Frequency response provided by Bruel Kjaer for
the manikin 4128 C, valid in conditions of
diffuse field and free field
Free field Diffused field
Gain (dB)
Frequency (Hz)
36
Equivalent sound levels outside the operator
ear, estimated using the frequency response
provided by BK for diffuse field.
Call center Amplification volume Sound level (dB(A)) Sound level (dB(A))
Call center Mean Standard dev. min max
Call center Level I 71.8 1.9 69.7 73.5
Call center Level II 77.8 1.7 75.9 80.7
Call center Level III 81.8 1.7 79.9 84.1
Call center Level I 77.3 1.3 75.9 78.5
Call center Level II 80.3 2.3 76.7 83.0
Call center Level III 84.2 1.7 82.4 87.0
Data from Peretti et al., 2002
37
The noise directive 2003/10/CE
News

• The new directive applies to all occupational
  fields. This is a clear improvement with respect
  to the old one.
• It introduces new action and limit value based on
  LEX,8h
• and/or to Lpeak
• limit value 87 dB(A) LEX,8h and/or 140 dB(C)
  Lpeak
• upper action value 85 dB(A) LEX,8h and/or 137
  dB(C) Lpeak
• lower action value 80 dB(A) LEX,8h and/or 135
  dB(C) Lpeak
• Decrease by 5 dB in the main requirements
  (formation, DPI, )
•  

38
The noise directive 2003/10/CE
Critical points
The limit value of 87 dB(A) proposed by the new
noise directive includes the hearing protectors.
In other words, the attenuation given by hearing
protectors has to be taken into account when
assessing if the limit is being adhered
to. Consequently, the limit value is not well
defined. The real protection given by personal
protective equipments is dependent on several
variables such as real environmental conditions,
wearing procedures and workers formation. The
average attenuation given by hearing protectors
is about 20 dB so the limit value is adhered to
also if the environmental levels rise to 110
dB(A) So the serious risk exists that the
employees will continue to be exposed to high
environmental noise level. The employee
protection could result to be based less on
technical and procedural measures to reduce noise
emission and exposure, and more on checking the
behaviour of employees.
39
The noise directive 2003/10/CE
Critical points
Another critical point is related to the fact
that in the new noise directive there are no
technical enclosures providing methodologic and
metrologic instructions for the measure of noise
exposure and of hearing function in exposed
workers. The lack of technical enclosures
requires detailed national guidelines to help the
operators in the field of occupational prevention
and safety. In Italy, ISPESL has promoted the
development of such guidelines, also providing
widespread diffusion of this information, which
is freely available online on the web page
http//www.ispesl.it/linee_guida/fattore_di_risch
io/rumore_eng.htm
40
Italian national guidelines on noise
National guidelines for evaluation of risk from
noise exposure in working places
41
Conclusions and outlooks
The aim of the new directive was to introduce
more protective standards for the noise exposure,
by shifting the requested countermeasures to the
immediately lower threshold level, and by setting
at 87 dB a threshold that must not be exceeded in
any case. On the other hand, the introduction of
DPI attenuation in the evaluation of the
effective noise level could lead to confusion and
metrological difficulties in practical
applications. The challenge that must be faced
by national institutions is that of explaining
how to apply the new criteria without the risk of
lowering the effective level of protection of
workers