Hand-Arm Vibration in a Foundry Fettling Shop
A foundry fettling shop employs 11 operatives on 8-hour shifts. Each operative uses a 115 mm angle grinder for about 3 hours 45 minutes per shift; the manufacturer declares a vibration magnitude of 7.2 m/s². A further 45 minutes is spent using a pedestal grinder declared at 2.8 m/s². There is no vibration risk assessment, no exposure calculation and no health surveillance. Two operatives report tingling and numbness in their fingers that wakes them at night; one has episodes of blanching on cold mornings. The operations manager proposes a job rotation between grinding and packing, but the packing role is only available for 45 minutes per shift and the same grinders are used by all operatives. He also proposes 'anti-vibration gloves' and a toolbox talk. Production pressure has increased following a new contract, and the workforce is told that 'the tingling is normal in fettling'.
1. Calculate the daily vibration exposure and assess whether the foundry is complying with the Control of Vibration at Work Regulations 2005. Explain the significance of the reported symptoms.
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Using A(8) = a × √(T/8):
- Angle grinder: 7.2 × √(3.75/8) = 4.93 m/s² A(8).
- Pedestal grinder: 2.8 × √(0.75/8) = 0.86 m/s² A(8).
- Combined: √(4.93² + 0.86²) = 5.00 m/s² A(8).
Exposure points are about 3,110 + 94 = 3,204 points. The exposure action value (2.5 m/s² A(8), 100 points) is greatly exceeded and the exposure limit value (5.0 m/s² A(8), 400 points) is reached. The employer is therefore in breach of the duty to assess and reduce exposure; the ELV must not be exceeded. The calculation also shows how misleading the 'rotation' proposal is: rotating to packing for 45 minutes does not reduce the total grinding time, so the A(8) is unchanged unless the person actually spends less time on the grinders.
The symptoms matter. Tingling and numbness that wake the operative at night, and blanching, are consistent with HAVS and are not 'normal'. They indicate that control has failed and that health surveillance is overdue. The employer must not wait for a diagnosis before acting; the symptoms trigger referral to occupational health and a review of exposure. Individual susceptibility varies, so a legal limit compliance figure does not prove safety.
2. Evaluate the control options available, including the manager's proposals. Recommend a prioritised action plan.
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Apply the hierarchy. Eliminate/substitute: automate or robotise fettling, or use a different process (e.g. cut-off rather than heavy grinding) where technically feasible. This is the only way to remove the hazard. Engineering: buy low-vibration grinders, maintain them, ensure correct and sharp discs, balance and mount workpieces, use jigs so the operator does not grip the tool as hard. Administrative: set trigger times based on measured tool data; create genuine rotation with periods of no vibration, not just different grinders; train on grip and posture; maintain a tool register.
The manager's proposals are weak. Anti-vibration gloves can reduce high-frequency vibration but are not effective for the dominant low-frequency vibration of angle grinders and must not be used as the main control. A toolbox talk does not reduce exposure. Rotation between grinding and packing for 45 minutes is only useful if the packing role is additional to the establishment and actually reduces each person's grinder time. Otherwise it redistributes the same exposure.
A prioritised plan: (1) stop the worst exposure by reducing trigger time immediately and reviewing the contract pressure; (2) procure low-vibration tools and introduce maintenance; (3) engineer out manual grinding where possible; (4) introduce health surveillance and referral; (5) train and consult; (6) re-measure to confirm A(8) is below the EAV, not merely the ELV. The aim should be ALARP, with the EAV as an action trigger and the ELV as a hard ceiling.
3. Advise on health surveillance and reporting, including whether RIDDOR applies.
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Health surveillance is required because the risk cannot be eliminated and there are already symptoms. Start with a baseline questionnaire for all 11 operatives, then annual checks; use a tiered scheme with occupational health. Anyone with tingling, numbness or blanching should be referred for further assessment, including to an HSE-appointed doctor where the regulations require it. Keep records for 40 years because HAVS can develop slowly. Surveillance is not a control measure: it detects harm early but does not make the exposure safe.
Adjust work for affected staff: reduce or remove vibration exposure, review tool use and provide advice on keeping warm and not smoking. Record the decisions.
On RIDDOR, HAVS is a reportable occupational disease when a doctor diagnoses it; the same applies to carpal tunnel syndrome where it is attributable to vibration. Do not report a suspicion from a toolbox talk, but once a diagnosis is made, check the reporting duty and submit the appropriate report. Also review whether the exposure incident or the failure of controls is reportable as a dangerous occurrence; that is less likely, so take advice rather than over-reporting. The key point is that reporting follows diagnosis and is not a substitute for prevention.