Exposure Action Value (EAV)
2.5 m/s² A(8). At or above this daily exposure, regulation 6 requires you to introduce technical or organisational measures to reduce vibration risk to as low as reasonably practicable. It's also one of the triggers for health surveillance under regulation 7.
Exposure Limit Value (ELV)
5 m/s² A(8). This must not be exceeded, other than under a narrow weekly-averaging exception in regulation 6(5) for specific controlled circumstances. Above it, exposure is unacceptable and must be brought down.
A(8): magnitude combined with time
A(8) expresses daily vibration exposure as a single figure, combining the vibration magnitude of a tool (in m/s²) with how long a worker actually holds the trigger each day, normalised to an 8-hour reference day. A high-magnitude tool used briefly and a lower-magnitude tool used for hours can produce a similar A(8) — magnitude alone doesn't tell you whether a job is compliant.
Exposure points
HSE also expresses exposure on a points scale, where the EAV equals 100 points and the ELV equals 400 points. It's the same underlying calculation as A(8), just rescaled — useful for adding up a worker's exposure across several tools used on the same shift.