How is daily vibration exposure (A(8)) calculated in practice?

Daily vibration exposure — often written as A(8) — represents the average vibration level a worker is exposed to over a standard 8-hour working day.

In practice, this is calculated by measuring vibration levels while an employee carries out normal tasks using a seat-mounted sensor. The measurement equipment records vibration intensity in metres per second squared (m/s²), which is then combined with the duration of exposure.

So for example, operating a vehicle with higher vibration levels for a short time might result in the same A(8) value as lower vibration over a longer period.

It’s essentially a way of standardising exposure so that different tasks or machine use patterns can be compared against regulatory action levels.