(i) Discuss what the information in supporting document 5 shows.
(ii) Using the HSE’s L108 appendix 4, explain how the information in supporting document 5 could be used to aid decision making with a hearing health surveillance programme.
(iii) Use the numerical information in the shaded area of supporting document 5 and in appendix 4 of L108 to determine the outcome of the audiometry testing for Worker Y. Note: You should use simple calculations to support your answer.
Supporting document 5
Health surveillance findings
page 1 of 1
Controlling noise at work
Appendix 4: Health
surveillance using
audiometric testing
1
Appendix 4 advises those health professionals (competent advisers) responsible for the
health surveillance programme on procedures for using pure tone audiometric testing, interpreting
results and record-keeping.
2
Industrial (or occupational) audiometry is a surveillance technique used to detect early
changes to hearing resulting from exposure to noise. Identifying hearing loss allows appropriate
follow-up actions in the workplace. Audiometry can be used to identify changes in hearing due to
many causes, including NIHL.
3
Health surveillance is required for all employees regularly and frequently exposed above the
upper EAVs and for individuals at greater or additional risk if exposed between the lower and
upper EAVs. See also paragraphs 261 and 262 in Part 5.
General approach
4
Before introducing any health surveillance it is important to agree the programme with the
employer and ensure that employees who will be under surveillance are aware of the implications
of the programme. It is important to discuss with the employer, employees and their safety
representatives:
(a)
(b)
(c)
(d)
(e)
the aims of the programme;
the procedures to ensure confidentiality of the results;
the methods to be followed, including those for medical referral;
the process if an abnormality is found;
the importance of analysing anonymised information.
5
There should be a competent adviser in charge of the health surveillance programme. The
competent adviser is likely to be a suitably qualified occupational health professional. This person
should be fully conversant with the technical and ethical aspects of the conduct of occupational
audiology, understand the relevant workplace risks and, in particular, be responsible for:
(a)
(b)
(c)
(d)
the quality of the service provided;
ensuring that appropriate standards are maintained during testing, including that
audiograms are correctly interpreted;
record-keeping;
any referral of individuals.
6
Ultimately, the employer has responsibility for ensuring the proper conduct of health
surveillance for noise-exposed employees. It is important to speak with the employer and reach
agreement on the detailed arrangements on referral for further advice and the procedures for
feedback of the results.
90
Appendix 4: Health surveillance using audiometric testing
7
The person performing the tests may not be the same person as the competent adviser
who interprets the audiogram results. The person actually conducting the tests needs to have,
as a minimum, appropriate training so that testing is carried out in a repeatable and accurate
manner. A suitable training syllabus has been prepared by the British Society of Audiology
(www.thebsa.org.uk). The main requirements for any person responsible for conducting
audiometric tests are that they should:
(a)
(b)
(c)
(d)
have a good understanding of the aims and technique of industrial audiometry and how
it relates to hearing conservation;
be competent to ensure an appropriate test environment, to operate and maintain the
testing equipment, undertaking basic calibration, and to carry out the test procedure;
understand and comply with the need for confidentiality of personal health information;
know how to present results according to a defined system.
Test environment
8
BS EN ISO 8253-131 gives criteria which should be met in test rooms to prevent test tones
being masked by ambient sound levels and to allow measurement of hearing thresholds down to
0 dB. The quietest listening conditions are required at test frequencies of 1 kHz and below. It is
highly likely to be necessary to use an audiometric soundproof booth to achieve acceptable
listening conditions. Although noise-excluding headsets have been recommended as an alternative
method to reducing the effects of ambient noise, variations in fit mean that it is not possible to be
certain of the attenuation achieved. Information should be obtained on the attenuation of the
headsets, tested according to BS EN ISO 4869-1, which can be used to determine acceptable
background levels.
Calibration
9
All equipment should be maintained and calibrated according to the recommendations of BS
EN ISO 8253-1. In summary, this standard requires that a listening check should be undertaken
daily before use and an experienced person with good hearing should listen at each frequency,
and ensure that the equipment is operating correctly. Other checks should be performed weekly
and quarterly with a complete overhaul and calibration made annually by a competent laboratory.
Many users rely on the manufacturer for this annual check, which should incorporate calibration of
the earphones with the audiometer. This can be important, as the earphones are often the
weakest link in the calibration chain since they are easily damaged in use.
Instrumentation
10 There are two main types of audiometers:
(a)
(b)
manual recording;
automatic recording.
11 These audiometers are designed to provide test tones at fixed frequencies and varying
intensities at the ears of the person under test. However, manual audiometry may be used where
an individual has difficulty co-operating with other techniques. Methods for manual audiometry are
included in BS EN ISO 8253.
Methodology
12
Testing should follow the methods described in BS EN ISO 8253-1 which advises on:
(a)
(b)
(c)
(d)
(e)
(f)
the need for otoscopic examination;
how to instruct the individual and fit earphones for the test;
audiometric equipment and its calibration;
test conditions;
the detailed conduct of the examination;
how to determine the hearing threshold level.
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Controlling noise at work
Pre-test examination
13 It is important that the person conducting the test has a record of the otological and noise
exposure history of the person being tested. Also, that they undertake otoscopic examination of
the ear immediately before the test to detect any major abnormality or the presence of exudate or
wax which might affect the results. The tester should also be familiar with any hearing protection
which may be used by workers so they can discuss proper fitting, cleaning and maintenance.
Quality control in audiometry
14 It is important that examinations are made under standardised test conditions with close
attention to quality control procedures. Quality control is important to improve the repeatability and
reliability of the data produced. Comparisons between test results are an important part of
interpretation in an ongoing and effective audiometric programme. All test results, therefore,
should be comparable by maintaining a standardised method of testing.
15 Careful explanation to the subject of the procedure and familiarisation with the test tones
before the test begins are also essential for the collection of reliable data. The criteria used to
determine the accuracy with which results are obtained include:
(a)
(b)
(c)
whether temporary threshold shift (TTS) is present;
appropriate and timely equipment calibration;
the presence of background noise in the test environment.
Temporary threshold shift
16 The best approach to audiometry in relation to the problem of TTS is to seek to eliminate its
influence by conducting tests before high exposures to noise occur. The best method to ensure
this is to test individuals before they start work, with advice on reducing noise exposure while
travelling to the test. However, this will not be practical in most situations. Alternatively, it may be
useful to advise employees to use additional hearing protection in the period before the test where
noise exposure will be present. The aim is to minimise the influence of TTS and to obtain, as far
as possible, a record of permanent changes to an individual’s hearing threshold.
17 Unless there is a prolonged period free from high noise levels before testing it is difficult to
exclude any contribution from TTS. It is important to ensure that tests are repeated, as far as
possible, in the same conditions from year to year. Where there are indications of hearing damage
needing medical referral, any follow-up should include an audiogram that is not influenced by TTS.
Schedule of testing
18 An audiometric programme should begin with a baseline audiogram conducted before
exposure to hazardous noise or as soon as possible after initial exposure, followed by a schedule
of audiometric testing to monitor hearing threshold levels over time. For quality control purposes it
is particularly important to obtain a baseline that, as far as possible, is not influenced by TTS. This
reflects the importance of this initial test as a reference point for all future comparisons.
19 At the baseline examination it is also important to obtain information about the individual’s
job, previous noise exposures and medical history (see example questionnaire in Appendix 5) in
order to establish fitness to work in a noisy environment and any adjustments or restrictions that
may be required. At all subsequent tests the individual should be asked about any changes in
personal circumstances, work patterns and noise exposure, and any complaints relating to the
ears or hearing. If changes are indicated, these should be recorded.
20 The schedule of audiometric testing should include annual tests for the first two years of
exposure and thereafter a test once every three years. More frequent testing may be required if
significant changes in hearing level are detected or the risk of hearing damage has increased.
As a quality control measure, it would be advisable to repeat any audiogram which showed a
difference from the previous result of more than 10 dB at any frequency.
92
Appendix 4: Health surveillance using audiometric testing
Interpretation of results
21 Where, as a result of health surveillance, the employee has identifiable hearing loss, the
diagnosis of NIHL must be confirmed by a doctor (unless the competent adviser is a doctor).
Fitness for work advice should then be provided by the competent adviser.
22 To provide help with decision-making and referral, a categorisation scheme has been
developed by HSE (see Table 12). In the categorisation scheme, the criteria for audiometric
classification are based on the presence or absence of NIHL and on a summation of the hearing
levels obtained at 1, 2, 3, 4 and 6 kHz. This calculation should be done for each ear separately.
The sums calculated should be compared with the values given for age and gender in Table 13.
Although this scheme recommends a sum of hearing levels at specific frequencies, it is important
that audiometry is still conducted at 0.5 and 8 kHz. Note that the categorisation scheme is only a
guide to help with interpretation of results and feedback to the employer. It should not replace a
full analysis of the audiogram.
Table 12 The HSE categorisation scheme
Category
NIHL seen on
audiogram?
Calculation †
Action
1 Acceptable
hearing ability
No*
Sum of hearing
levels at 1, 2, 3, 4
and 6 kHz
Repeat health surveillance
at next routine interval
2 Mild hearing loss
Stable NIHL may be
present+
Sum of hearing
levels at 1, 2, 3, 4
and 6 kHz
Consider earlier repeat
health surveillance than
routine, taking into
account factors such as
extent of hearing loss
3 Significant hearing Yes, newly identified
loss or new/
or progressive NIHL
progressive NIHL
may be present (this
category may also
include more severe
but stable NIHL)
Sum of hearing
levels at 1, 2, 3, 4
and 6 kHz
Refer for medical
assessment.
Timing of next health
surveillance depends on
outcome of assessment
4 Rapid hearing
loss+
Reduction in hearing
level of 30 dB or
more, within 3 years
or less
Sum of hearing
levels at 3, 4 and
6 kHz
Refer for medical
assessment.
Timing of next health
surveillance depends on
outcome of assessment
Possible
* If NIHL is or may be present, the worker cannot be Category 1.
+ By definition at least one previous audiogram must be available for comparison.
† Compare value with figure given for appropriate age band and gender in Table 13.
Method for using the categorisation scheme
23 Once the test has been completed, the relevant quality control issues have been taken into
consideration, and a noise and health questionnaire completed, the following steps should be
carried out to categorise the audiogram. Each category has a descriptor relating to the condition of
an individual’s hearing and advises what steps should be taken next. Table 12 provides details of
the four categories.
24 Firstly, the audiogram should be assessed for the possible presence of NIHL.
This should be undertaken by an appropriately qualified individual, eg an occupational health
professional. Where NIHL is newly identified or progressive, the worker should be placed in
Category 3 and be referred for medical assessment by an appropriately trained doctor, eg
occupational physician.
93
Controlling noise at work
25 Next, the hearing levels obtained at the 1, 2, 3, 4 and 6 kHz frequencies should be added
so that a single value is obtained for each ear. Table 13 provides the relevant thresholds for these
sums, taking into account the age and gender of the individual:
(a)
(b)
(c)
If the sum for both ears is below the mild hearing loss level and the audiogram does
not show evidence of NIHL, then that individual will fall within Category 1 – acceptable
hearing ability.
If the sum for either ear is equal to or exceeds the mild hearing loss threshold level for
their respective age and gender, then the individual will fall into Category 2 – mild
hearing loss. This category may include stable, but less severe NIHL.
If the sum is equal to or exceeds the significant hearing loss level for either ear or new or
progressive NIHL is present, then the individual would fall into Category 3 – significant
hearing loss or new or progressive NIHL present and would require referral for medical
advice. This category may include stable, but more severe NIHL. Where hearing loss is
stable, the worker has previously undergone medical assessment, and there are no
significant changes at subsequent health surveillance, repeat medical assessment may
not be necessary. Where new or progressive NIHL eventually stabilises, depending on the
sum of hearing levels, the worker may be reclassified into Category 2.
26 To determine whether there has been a rapid loss in hearing since the last examination a
sum of the hearing thresholds obtained at 3, 4 and 6 kHz should be made. If the previous test was
performed within the last three years and an increase in hearing threshold level of 30 dB or more
(as a sum of 3, 4 and 6 kHz) is found then this individual would fall into Category 4 (rapid hearing
loss) and require referral for further medical advice.
27 A further sum should be undertaken to determine whether the individual has any unilateral
hearing loss suggesting a problem due to disease or infection. Sum the hearing levels at 1, 2, 3
and 4 kHz for both ears. If the difference between the ears is greater than 40 dB the individual
should be advised of the findings and referred for medical advice.
Table 13 Classification of audiograms
Sum of hearing levels 1, 2, 3, 4 and 6 kHz
Age
Males
Females
Mild hearing loss
level
Significant
hearing loss level
Mild hearing loss
level
Significant
hearing loss level
18–24
51
95
46
78
25–29
67
113
55
91
30–34
82
132
63
105
35–39
100
154
71
119
40–44
121
183
80
134
45–49
142
211
93
153
50–54
165
240
111
176
55–59
190
269
131
204
60–64
217
296
157
235
65+
235
311
175
255
28 Further tests may be required to ascertain the causes of any abnormal audiogram. These
will be conducted following referral to a doctor or specialist.
Actions/advice
29 It is essential that all individuals understand the importance of full and proper use of hearing
protectors as part of the health surveillance programme (further information is available in
Appendix 5 Example 1, other sections of this guidance book or on HSE’s noise webpages:
www.hse.gov.uk/noise).
94
Appendix 4: Health surveillance using audiometric testing
30 Whenever abnormal hearing is found, advice should be given to that employee which should
include reference to the extent and implication of the damage and ways in which to prevent any
further damage or loss. Retraining and reinforcement of the correct use of hearing protection and
the importance of complying with other hearing conservation methods provided by the employer
are the main points to stress.
31 Arrangements and procedures should be put in place for referral of those individuals with
hearing loss that might be noise-induced and where rapid or unilateral hearing loss is identified.
The frequency of any subsequent testing will be defined by the nature and progression of any
abnormalities found.
Serial audiograms
32 Where serial audiograms are available, they should be used for comparison with the latest
audiogram, looking for any significant change that may be present. The competent adviser should
have the knowledge and experience necessary to undertake this.
Other actions
33 Where the categorisation and examination of the audiogram have not triggered a referral,
but it is clear that hearing loss has become problematic for the individual, it may be appropriate
for the employee to see their GP. This hearing loss may not indicate anything other than normal
ageing. The same consideration applies where an individual reports symptoms such as ear pain,
discharge, dizziness, severe or persistent tinnitus, fluctuating hearing impairment or a feeling of
fullness or discomfort in one or both ears.
34 Where there is concern about changes in hearing thresholds, or where there is an increase in
workplace risk, a repeat audiogram should be undertaken before the next scheduled routine test.
Record-keeping
35 The competent adviser should provide the employer with fitness for work information and
health surveillance dates (completed and scheduled) but not audiometric results unless employee
consent has been given. Employers should keep a health record as long as an individual remains
in their employment, and may wish to retain it for longer as enquiries regarding the state of an
individual’s hearing may arise many years after exposure to noise has ceased.
36 The competent adviser should ensure that adequate medical records are maintained.
Audiometric results and noise and health questionnaires are medical-in-confidence information.
Consent is necessary before passing results of testing to the employee’s GP or anyone else.
37 Employers should see anonymised grouped data on the hearing of the workforce to help
assess the effectiveness of their noise-control measures (see paragraph 41 below). This should be
done in a way that does not reveal details of any particular individual’s hearing threshold and does
not compromise the issue of confidentiality. Consent will not be required for this information to be
provided to the employer.
38
Figure 29 provides an outline of the procedures to follow in an audiometric testing programme.
Future work in noisy environments
39 If any NIHL is deemed to be stable by a competent adviser, continuing exposure to noise will
usually be acceptable where adequate hearing protection and control measures are used, and
where residual hearing ability is not so poor as to make the risk of further hearing loss
unacceptable. An increased frequency of health surveillance may be required. In exceptional
circumstances the competent adviser may indicate to the employer that an individual is no longer
fit for their current role.
95
Controlling noise at work
40 The analysis of individual health surveillance results should not focus solely on the
categorisation of hearing loss but also take account of workplace risks. These could include the
need to communicate effectively for safety reasons or the need to hear warning signals.
Audiometric assessment based on the average hearing threshold over the speech frequencies, or
those of particular warning sounds, may be helpful but are not detailed here. Regardless of its
cause, where significant hearing loss is found, an assessment of fitness for work which considers
the workplace risks should be made.
Information for the employer
41 Grouped, anonymised analysis of audiometric results can provide useful information to the
employer about the overall effectiveness of a hearing conservation programme. The analysis can
be a simple tabular presentation of the percentage of workers falling into each category compared
with previous test results (as long as there has not been a significant change in the work
population). This may be broken down for different groups of workers or different areas of the
workplace. Computerised audiometer systems may be pre-programmed to provide such
information. The form of assessment which is appropriate often depends on the number of
workers exposed to noise. This type of anonymised interpretation of the results does not
compromise confidentiality provided the groups are sufficiently large.
42 Where analysis of the audiometric results demonstrates that there has been deterioration in
hearing, perhaps in particular groups of workers, a reassessment of the exposure factors will be
required. The results may reflect a change in exposure conditions; for example, as a result of
relocation of machinery, changes to working patterns, inadequate maintenance of machinery or a
failure of hearing conservation methods, in particular, failure or ineffective use of hearing protection.
96
Appendix 4: Health surveillance using audiometric testing
Baseline/first test
Subsequent tests
Do Part 1 of noise and health
questionnaire – personal details,
job, previous exposures, medical
history
Obtain records for the individual,
including last audiograms. Ask if
there has been any change in
personal details or job – if so,
amend Part 1 of noise and health
questionnaire
Conduct otoscopic examination
Conduct test
Assess the audiogram
(competent person) and make
comparison with the last test
Assess the audiogram
(competent person)
Repeat any audiogram which shows
a difference from the previous result
of more than 10 dB at any frequency
Is NIHL present?
Yes
No
Is this newly identified or
progressive NIHL?
No
Yes
Sum the hearing level obtained
at 1, 2, 3, 4 and 6 kHz
for each ear
Sum the hearing levels at 3, 4
and 6 kHz for each ear to see if
rapid hearing loss has occurred
since last test
Sum the hearing levels at 1, 2, 3
and 4 kHz for possible unilateral
hearing loss
Analyse results using categorisation
scheme
Medical assessment
Category 3, Category 4
or unilateral hearing loss
Category 1 or
Category 2
To employer – Give fitness for work advice and state when next test is due
To employees – Inform of results, provide advice and state when next test is due
Figure 29 Flow diagram for audiometric testing and categorisation
97
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