Prolonged exposure to harmful noise levels can cause permanent hearing loss.
The higher the sound levels and the longer the exposure to them, the bigger the risk of hearing loss and the more severe it is. The scientific understanding is that exposure to a sound level of no more than 80 dB(A) for eight hours per days is still barely safe. The maximum sound levels for exposure of less than eight hours are listed in the below table. Any exposure to the sound levels beyond the time limits indicated may cause hearing loss.
Maximum daily unprotected exposure time per sound level
Besides hearing loss (auditive effect), non-auditive effects like fatigue, testiness, dizziness, raised blood pressure, stress, startle reflexes and loss of perception may also occur.
Noise-induced hearing loss cannot be cured.
Noise is not just a health hazard, it can also disrupt communication and break one's concentration when performing tasks.
Dutch legislation lists two maximum noise levels:
- maximum daily exposure level for noise not to be a health hazard: 80 dB(A);
- maximum daily exposure level for employers to take protective measures:
The government has determined the average sound level exposure to an excess of which may cause hearing loss in humans - when exposed to it for eight hours a day - to be 80 dB(A). In the workplace, the average noise level over eight hours may not exceed 85 dB(A). This means that when noise levels exceed 85 dB(A), effective measures have to be implemented to reduce the exposure to the noise, unless this is not, within reason, feasible, due to excessively high costs, for technical reasons, etc.
When the noise level exceeds 80 dB(A), the employer is to make hearing protection available. When the noise level exceeds 85 dB(A), employees are required to make use of such hearing protection. All spaces in which the noise level exceeds 85 dB(A) need to be clearly demarcated and marked.
Organizations are required to allow their employees who, during the performance of their work, are exposed to a daily dose of over 80 dB(A) to apply for an audiometric examination - the so-called hearing test (Section 18 of the Working Conditions Act: occupational health medical examination). Employees exposed to noise levels of over 80 dB(A) are to be informed about the risks of being exposed to noise, the measures implemented to limit exposure and the possibility of having a hearing test taken.
Hazard identification and risk assessment (RI&E)
Section 6.7 of the Working Conditions Decree states that noise levels are to be assessed and where necessary measured in all workplaces for reasons of hazard identification and risk assessment, so as to determine where and to what extent employees may be exposed to harmful noise levels. The assessment and measurement are to be of noise levels representative of the exposure to noise during daily work hours. The assessment and measurement are to be recorded in writing and to be periodically repeated. Should the RI&E determine that noise levels at the workplace are too high, measures are to be implemented to reduce these levels. These measures are to be laid down in an Action Plan (or noise control plan).
AnRI&E of any work activities which are expected to result in high levels of noise (i.e. over 80 dB(A)) needs to have been conducted prior to the start of those activities. The RI&E is to concern the risks of employees being exposed to too much noise. The following needs to be addressed:
I Noise level information:
Sound level measurements are to be conducted in accordance with the NEN 3418 standard. This requires a proper sound meter and the expertise to operate the device. Ask the HR Directorate occupational hygienist for advice. The following rule of thumb allows for a very indicative estimate: if a conversation cannot be held at normal tone at a distance of 1 metre from the source of the noise, noise levels are likely to be over 80 dB(A)
Information on noise
Should such information be available: noise frequency (in Hz), reverberation time, etc.
For example: measures already implemented to reduce noise.
Note: Employers are to store and keep the noise level assessment, noise level measurement and noise level calculation results for at least ten years. The same applies for all hearing test results.
II Type of work
What sort of work causes the noise (machinery, work activities), and are the noise levels reached intermittently or constantly?
III Employees exposed to noise
Which employees (students and technicians) are exposed to the high noise levels?
Have all these employees been informed about the risks of high noise levels?
Is medical information (audiograms) available on all employees exposed to high noise levels?
IV Action Plan
An occupational hygiene strategy is to be in place to prevent exposure to harmful noise. This strategy is to distinguish between the following four levels of measures to be taken, ordered by priority:
- Controlling noise at the source (remove machinery);
- Isolating the source/reducing noise transmission (enclose machinery);
- Isolating the worker/reducing exposure (noisy machinery in separate room);
- Using personal hearing protection (otoplastics, earmuffs).
Technical and organizational measures
Employees exposed to noise levels of over 80 dB(A) are to be informed on:
- The possible hearing hazards of being exposed to the noise;
- Legislation in force on the topic of noise and all measures to be implemented by law;
- Those situations in which hearing protection is made available and those situations in which use of protection is required;
- How hearing protection is to be used;
- The nature and objectives of periodically repeated audiometric examination and when employees are provided the opportunity to have such an examination performed.
Demarcation and marking:
All spaces within which noise levels are over 85 dB(A) are to be marked by a blue, round sign showing a white pictogram of an earmuff, and all tools producing noise of over 85 dB(A) are to be clearly marked with a sticker.
Occupational health medical examination
All employees exposed to noise levels of over 80 db(A) during their work are to be periodically granted the opportunity by the supervisor to have an audiometric examination performed. The objective of this examination is to monitor and regularly check up on the employee's hearing.
The frequency of offering such examinations depends on the noise levels in the workplace and the sensitivity of the individual employee. Regular, daily exposure to over 87 dB(A) may require the examinations to be offered annually.
Working conditions information sheet 4: Noise in the workplace
Working Conditions Decree, Chapter 6