OSH Seminar, Bucharest, October 20-21, 2005 1 The implementation of the noise directives in a Member State Renata Sisto Department of Occupational Hygiene

OSH Seminar, Bucharest, October 20-21, 2005 1

The implementation of the noise directives in a Member State

Renata Sisto

Department of Occupational HygieneMonte Porzio Catone (Roma), ITALY

[email protected]


• 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

SUMMARY


Industry, services and agriculture - years 1999÷2004. (data from Italian National Institute of Public Accident Insurance INAIL )

N: Notified on suspicion R: recognized and refunded

Noise / Hearing Loss

Notification

year

Hearing impairment in listed occupational fields

Hearing impairment in non listed occupational

fields

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



0

2000

4000

6000

8000

10000

12000

14000

1999 2000 2001 2002 2003 2004

Notification year

Occupational hearing impairment cases notified on suspicion to INAIL(industry, services, agriculture)

Occupational Hearingimpairment



0

500

1000

1500

2000

2500

1999 2000 2001 2002 2003 2004

Occupational hearing impairment cases recognized and refunded by INAIL(industry and services)

Occupational hearingimpairment casesrecognized by INAIL


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

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.

Noise / Hearing loss


Aging-induced hearing loss H

eari

ng

thre

shol

d d

B20 years

30 years

50 years

60 years

65 years


Noise-induced hearing lossH

eari

ng

thre

shol

d d

B

Exp

osu

re

dura

tion

(ye

ars)


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(/0)](Lex, 8h – L0)2

where u, v and L0 are functions of frequency and is the duration in years of the exposure


The ISO 1999 (1990) standardNIPTS relative to fiftieth percentile at 4000 Hz

0

5

10

15

20

25

30

35

40

45

0 5 10 15 20 25 30 35Exposure time (years)

Per

man

ent

Th

resh

old

Sh

ift

(dB

)

NIPTS Lexp 80NIPTS Lexp 87NIPTS Lexp 95,7NIPTS Lexp 100


It is the standard currently used to estimate the dose-effect relationalso 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

The ISO 1999: 1990 standard


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.


Outer hair cells (OHCs) schematicsOuter hair cells (OHCs) schematics

TM

BM

IHC=mechano-electrical transduction

OHC=electro-mechanical transduction


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, 10dB<HT≤20dB), 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.


Comparison of average audiometric thresholds between a population of young (mean age=30 years) exposed (MHL,

HL) and non exposed subjects (Normal)

-30

-25

-20

-15

-10

-5

0

0 2000 4000 6000 8000 10000f (Hz)

Hea

rin

g L

os

s (d

B H

TL

)

Normal

MHL

HL

non exposed

exposed

exposed


A new diagnostic technique based on otoacoustic emissions can be used to detect the early effects of noise exposure

exposed

exposed

TEOAE SNR in third of octave bands

-5

0

5

10

15

20

0 1000 2000 3000 4000 5000 6000

f (Hz)

TE

OA

E S

NR

(d

B)

HL

MHL

not exposed

Comparison of TEOAE SNR between a population of young (mean age=30 years) exposed (MHL, HL) and non exposed subjects


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.

Noise / State of the Art



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.




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) < LEX, 8h < 90dB(A) are about 12000.

These data are evidently underestimated, if one thinks

that there are in Italy more than three millions of

companies



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.

Noise / Risk evaluation


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

Noise / Risk evaluation in schools


Noise / Risk evaluation in schoolsMaternal 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


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)

Noise / Technical reports


Hearing protectors

Attenuation is a statistical variable characterized at each octave frequency band by a mean value and by a standard deviation

)()()( fsfmfAPV This statistical aspect is often neglected in technical reports so leading to an underestimate of the actual noise exposure.


Gaussian probability distribution

0

2

4

6

8

10

15 20 25 30 35 40 45

attenuazione (dB)

dens

ità

di p

roba

bili

tà (

%)

m-s m+s34% 34%

Population in the interval between m-s and m+s

Pro

babi

lity

den

sity

Attenuation (dB)


Gaussian probability distribution

0

2

4

6

8

10

15 20 25 30 35 40 45

attenuazione(dB)

dens

ità

di p

roba

bili

tà (

%)

m-s84%

The mean attenuation m(f) minus 1 standard deviation, (m-s), is the minimum attenuation for 84 % of the population of exposed subjects

Attenuation (dB)

Pro

babi

lity

den

sity


m - s

The choice = 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.


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 different1) workers are not formed to the use of hearing protectors2) the wearing conditions are not optimized3) the size is often not optimized4) there are anthropometric differences in the external ear 5) the hearing protectors have to be worn for a long time6) there are uncontrolled movements (mandibular, etc.)7) the wearing conditions are affected by physical activity8) discomfort

The attenuation of hearing protectors in working places are lower than those declared by manufacturer


Hearing protectors / Real attenuation

0

10

20

30

40

50

60

frequenza (Hz)

atte

nuaz

ione

(dB

)ambiente dilavoro(min)ambiente dilavoro(max)produttore

1000 2000 4000 8000500250125

MuffleMean attenuations and their standard deviations declared by manufacturer compared to those measured in a real work environment

Work enviroment(min)

Work enviroment(max)

Declared by manufacturer

Frequency (Hz)


Hearing protectors / Formation effect

0

10

20

30

40

50

60

frequenza (Hz)

atte

nuaz

ione

(dB

)

nessunaistruzioneistruzioni acorredodimostrazione praticaproduttore

1000 2000 4000 8000500250125

0

10

20

30

40

50

60

frequenza (Hz)

atte

nuaz

ione

(dB

)

nessunaistruzione

istruzioni acorredo

dimostrazionepratica

produttore

1000 2000 4000 8000500250125

0

10

20

30

40

50

60

nessunaistruzioneistruzioni acorredodimostrazione praticaproduttore

No instructions

With instructions

Practical demonstration


No instructions

With instructions

Practical demonstration



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.

Risk evaluation in call centers


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

Methodology and instrumentation for the inside and outside evaluation of noise


Manikin used for the measurements

Manikin: B&K 4128

Right Ear: B&K 4158

Left Ear: B&K 4159

Outer Ear: B&K DZ 9752


Frequency response provided by Bruel & Kjaer for the manikin 4128 C, valid in conditions of diffuse field and free field

0

2

4

6

8

10

12

14

16

18

20 40 80 160 315 630 1.25k 2.5k 5k 10k 20k

Frequenza (Hz)

Guad

agno (

dB)

B&K campo libero

B&K campo diffuso

Frequency (Hz)

Gai

n (d

B)

Free fieldDiffused field


Equivalent sound levels outside the operator ear, estimated using the frequency response provided by B&K for diffuse field.

Data from Peretti et al., 2002

Call center

Amplification volume

Sound level (dB(A))

Mean Standard dev.

min max

Level I 71.8 1.9 69.7 73.5

Level II 77.8 1.7 75.9 80.7

Level III 81.8 1.7 79.9 84.1

Level I 77.3 1.3 75.9 78.5

Level II 80.3 2.3 76.7 83.0

Level III 84.2 1.7 82.4 87.0


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, …)

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.


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_rischio/rumore_eng.htm


Italian national guidelines on noise

National guidelines for evaluation of risk from noise exposure in working places


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

Documents

OSH Seminar, Bucharest, October 20-21, 2005 1 The implementation of the noise directives in a Member State Renata Sisto Department of Occupational Hygiene