Hand-arm vibration syndrome is permanent. Once the nerve and blood vessel damage is done, it does not recover — which is why the assessment matters long before anyone reports a symptom.
The Control of Vibration at Work Regulations 2005 set two values, and both are measured over an eight-hour day:
- Exposure action value — 2.5 m/s² A(8): introduce controls and provide health surveillance
- Exposure limit value — 5 m/s² A(8): must not be exceeded
Do you know the daily vibration exposure for your highest-risk tool?
Not the tool's rating — the exposure of the person using it
Trigger time is what you are actually measuring
The most common assessment error is treating a tool's vibration rating as the exposure. It is not. Exposure depends on two things: how much the tool vibrates, and how long it vibrates in someone's hand.
That second figure is trigger time — time the tool is genuinely running under load. Not time on site, not time on the task, not the length of the shift.
A grinder used for forty minutes of actual cutting across a full day produces forty minutes of exposure, not eight hours. Equally, a moderate-vibration tool used almost continuously can generate more exposure than a fierce one used in short bursts.
People consistently overestimate trigger time when asked, because the task feels longer than the trigger is pulled. Where the assessment sits close to a value, it is worth timing rather than estimating.
The exposure points system
Because exposure is measured as an eight-hour average, adding up several tools across a day is awkward arithmetic. HSE's points system exists to make it workable.
Each tool, at its vibration magnitude, accumulates points per hour of trigger time. You add the points for everything a person uses in the day and compare the total against two thresholds:
Exposure points thresholds
| Total daily points | Equivalent | What it means |
|---|---|---|
| 100 points | 2.5 m/s² A(8) | Exposure action value — controls and health surveillance required |
| 400 points | 5 m/s² A(8) | Exposure limit value — must not be exceeded |
Points are additive, which is the whole advantage. A person using three different tools has one total, and you can see immediately which tool is contributing most — and therefore which one to change first.
Note the relationship is not linear: doubling the magnitude quadruples the points. Halving the vibration of the worst tool does far more than trimming trigger time everywhere.
Where the magnitude figure should come from
Manufacturers' declared values come from standardised tests, and real work rarely resembles the test. Blunt consumables, hard materials, awkward postures and worn tools all push actual vibration above the declared figure.
Use declared values for initial screening. Where the result lands anywhere near an action value, treat that as a prompt to get real measurements rather than a pass.
An assessment that concludes "just under the action value" on manufacturer figures alone is the weakest position to be in. It is the exact scenario where actual exposure is likely to be higher, and where you have decided against health surveillance on the strength of an optimistic number.
Controlling it
Work down the hierarchy, as with any risk:
- Eliminate the vibration — can the job be done another way, or the work bought in already processed?
- Substitute — lower-vibration tools, or a different technique entirely
- Reduce trigger time — job rotation, better consumables, correct tool for the material
- Maintain — blunt discs and worn bearings raise vibration considerably
- Support the worker — keep hands warm and dry, since cold worsens the vascular effects
Anti-vibration gloves are not a reliable control. They can reduce higher frequencies while doing little at the frequencies that cause HAVS, and they may increase grip force, which makes exposure worse. They are not a substitute for reducing vibration at source.
Health surveillance
Where the risk assessment indicates a risk, or exposure reaches the action value, regulation 7 of the Vibration Regulations requires health surveillance.
It is tiered specifically so that small employers are not sending everyone for clinical assessment. A short annual questionnaire, administered properly and acted on, covers people with no symptoms; assessment escalates only when symptoms appear.
Note that the Vibration Regulations set no retention period for the health record, unlike COSHH. Our guide to health surveillance records explains why you should still keep them for 40 years.
Common mistakes
Using the tool rating as the exposure. Magnitude without trigger time is half a calculation.
Estimating trigger time from memory. People overestimate it, which sounds cautious but produces assessments nobody believes and controls aimed at the wrong tool.
Relying on manufacturers' figures near a limit. Test conditions flatter tools.
Trusting anti-vibration gloves. They are not a control at the frequencies that matter.
Assessing the tool rather than the person. Someone using three tools has one daily exposure, not three separate ones.
Where this fits
See occupational health for how vibration sits alongside noise and substance exposure, and HSG170 — Vibration solutions for practical ways to reduce it. The underlying duty is covered in risk assessment.