A noise assessment is the gathering and analysis of data concerning the noise levels within the workplace and the risks that these may present to employees and others. It should consider ‘worst case’ scenarios, i.e. all noise sources operating at once and, where applicable, producing the highest noise levels under normal working conditions, e.g. stainless steel in a lathe instead of aluminium.
Such a noise assessment may need a sound level meter, but an initial indication can be drawn from the following table, taken from Controlling noise at work the Approved Code of Practice (ACoP) on Noise, L108.
|
Test |
Probable Noise Level |
Risk Assessment needed if the noise is like this for more than: |
|
The noise is intrusive but normal conversation is possible |
80 dB |
6 hours |
|
You have to shout to talk to someone 2m away |
85 dB |
2 hours |
|
You have to shout to talk to someone 1m away |
90 dB |
45 minutes |
Using a sound level meter
If your noise assessment requires the use of a sound level meter, it should be conducted by a competent person, either your qualified in-house safety adviser or a consultant occupational hygienist or similar.
This is necessary because there can be many variables to consider including:
- the type of meter (integrated or spectrum);
- the type of exposure (personal or location);
- the number of readings needed to account for all the significant factors (e.g. harmonics or reflected noise);
- the duration of the survey;
- instructions to people being surveyed (for personal samples); and
- any other relevant aspects to the survey being conducted.
The risk assessment should consider all aspects relative to the exposure, including:
- the recorded noise levels;
- working practices including duration of exposure and actual use of hearing protectors;
- the attenuation performance of hearing protectors being used;
- the condition of hearing protectors being used and whether they are being properly used;
- any training provided to the operators; and
- any safety issues related to the assessed noise levels (e.g. will the noise levels mask audible warnings or alarms etc.?).
Noise calculator
To help you assess the noise dose that an operator is subjected to when working in a noisy environment, the HSE has made a noise calculator available. The web page is shown in the chart below with some example entries for demonstration only.
In the ‘Exposure Calculator’ at the top of the chart, a range of eight noise levels has been entered, all with one hour exposure. The ‘Fractional Exposure’ values on the right-hand side have been calculated by the system, based on the noise level and exposure time.
As you can see, the Fractional Exposure values rise rapidly whereas the Noise Levels are rising nearly uniformly. This demonstrates how quickly the noise dose rises, especially at higher dB(A) readings.
The L EP,D value of 97.7 at the bottom of the Exposure Calculator is the total noise dose that would be received for all the entries in the table above. In this case, the eight one hour exposures at the different noise levels.
A ‘reverse’ calculation is also possible as shown in the ‘Exposure time calculator’. This enables you to specify a target daily dose level (87 has been entered as an example) for which the system then calculates the durations at that level to reach the four exposure and action values from both the new and old noise regulations. In the example shown above, in an environment with a noise level of 87 dB(A), it would take only 1 hour 35 minutes’ exposure to reach an L EP,D value of 80 dB(A).
The noise assessment record form can be used to record the details of a noise assessment, including the values taken from the HSE calculator.
A full report and action plan should be presented to the line manager(s) of the area(s) covered by the risk assessment and its findings.