The LEP,d is a worker's daily exposure to noise at work (normalised to an 8 hour day), taking into account the average levels of noise and the time spent in each area. This is the parameter that is used by the Noise at Work Regulations and is essential in assessing a workers exposure and what action should be taken.

How to Get the LEP,d / LEX,8hr

There are two ways to obtain a worker's LEP,d (daily noise exposure level):

Using a Sound Level Meter, measure the LAeq (average sound level) at each working location and find out how long the worker spends at each location.

Using a Noise Dosimeter that mounts on the worker's shoulder, measure for the full working shift. The dosimeter will provide you with the LEP,d.

If you take Option 2, you can ignore the bits below as you already have the LEP,d.

Using a sound level meter, make measurements at each of the noisy locations and find out how long the worker spends at each of those locations. For example:

We often get asked for a 12 hour LEP,d because "my workers do a longer shift than 8 hours". This results from a misunderstanding of the LEP,d. The limits and action levels in the regulations are written around the total noise that a worker can be exposed to over an 8 hour period. If you work for a longer or shorter period then the calculation of LEP,d takes this into account.

The calculation of LEP,d includes the noise level at each location and the time spent at each location. It then works out what the equivalent 8-hour level is (the LEP,d) so you can compare it against the action levels.

The HSE guidelines state that you should measure the LAeq, which is the average sound level. To measure this you need an integrating sound level meter, not just a basic sound level meter.