Hand-arm vibration syndrome is a permanent injury caused by regular use of vibrating tools. It starts as tingling and numbness, progresses to loss of grip and dexterity, and does not reverse. The Control of Vibration at Work Regulations 2005 control it by limiting daily exposure, expressed as an eight-hour energy-equivalent value written A(8), which combines how much vibration the tool produces with how long it is used.
The exposure values
Regulation 4 sets, for hand-arm vibration, a daily exposure limit value of 5 m/s2 A(8) and a daily exposure action value of 2.5 m/s2 A(8). For whole body vibration the daily exposure limit value is 1.15 m/s2 A(8) and the daily exposure action value is 0.5 m/s2 A(8). Crossing the action value triggers control measures and health surveillance; the limit value must not be exceeded.
How a HAVS calculator works
It combines the tool's vibration magnitude with trigger time, which is time the tool is actually vibrating in the hand rather than time on the job. Doubling the magnitude cuts the permitted time to a quarter, because exposure goes with the square of magnitude. That relationship is why a slightly worse tool matters more than people expect, and why measuring trigger time honestly matters more than the tool's data sheet.
Why the manufacturer's figure is usually optimistic
Declared vibration values are measured under standard test conditions, on a new tool, by a competent operator, on a defined material. Real exposure is on a worn tool, with a blunt consumable, in awkward positions. HSE's own advice is to treat declared values as a starting point and to use in-use data where it is available, which is what a monitoring service supplies.
What vibration monitoring services provide
Either a measurement survey producing in-use magnitudes for your tools and tasks, or on-tool monitoring that logs actual trigger time per operator per day, or both. The logging kind is what changes behaviour, because it turns an estimate into a number a supervisor can act on before somebody reaches the limit value rather than after.
Health surveillance is the other half
Above the action value, health surveillance is required. It is tiered, starting with a short annual questionnaire and escalating to assessment by a qualified person where symptoms appear. Its purpose is to catch the reversible early stage, so a scheme that only records that everybody is fine is not doing the job it exists for.
Questions people ask about vibration monitoring
What is the hand-arm vibration exposure action value?
A daily exposure action value of 2.5 m/s2 A(8). The daily exposure limit value is 5 m/s2 A(8).
What is the whole body vibration action value?
A daily exposure action value of 0.5 m/s2 A(8), with a daily exposure limit value of 1.15 m/s2 A(8).
Is HAVS reversible?
The earliest stages can improve if exposure stops. Established vascular and neurological damage does not reverse, which is why health surveillance aims to catch it early.
Do I have to measure vibration, or can I estimate?
You may estimate from reliable data, including manufacturers' declared values used cautiously. Measurement is needed where the estimate is close to an action or limit value or where the tools are worn or used unusually.