Hand-arm vibration and noise in a stonemasonry workshop
A stonemasonry workshop employs 14 people who use angle grinders and pneumatic chisels for 5-6 hours per shift. A consultant's assessment reports an A(8) vibration exposure of 5.1 m/s² and noise of 89 dB(A) Lep,d. The grinders are old, some anti-vibration mounts are missing, and workers say 'the tools have always been like that'. Three workers report tingling and numbness in their fingers at night; one has been diagnosed with early hand-arm vibration syndrome. Hearing tests show two workers with a 15 dB notch at 4 kHz in the left ear compared with previous tests. Management has issued gloves and earplugs and believes this is enough. The workshop is cold in winter and workers smoke during breaks.
1. Assess the exposure against the relevant action and limit values for vibration and noise, and explain the significance of the health findings.
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Vibration: 5.1 m/s² A(8) exceeds the exposure action value (2.5 m/s²) and the exposure limit value (5.0 m/s²). Exposure above the limit is not permitted; action must be taken to reduce exposure below 5.0 immediately, and to ALARP below 2.5. Noise: 89 dB(A) Lep,d exceeds the upper action value (85 dB(A)) and the limit value (87 dB(A)) before considering hearing protection. The limit value is stated at the ear, so the adequacy of earplugs must be checked; if the at-ear exposure is still above 87, the limit is breached. Health findings: tingling and numbness, and a diagnosed early HAVS case, are consistent with excessive vibration. The 15 dB notch at 4 kHz suggests noise-induced hearing loss, but a single test is not conclusive and needs confirmatory audiometry. The findings show controls have failed, not that PPE is sufficient.
2. Recommend a control programme, ranking actions by urgency and expected effectiveness.
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Urgent (this week)
- Reduce trigger time: rotate workers off grinders and chisels, introduce breaks, and stop the diagnosed worker from further vibration exposure.
- Maintain tools: replace missing anti-vibration mounts, balance grinders, and use low-vibration tools.
- Check hearing protection: fit-test, train and enforce use in designated zones; reduce noise at source with enclosures and damping.
Short term (1-3 months)
- Substitute pneumatic chisels with lower-vibration alternatives where feasible; mechanise or remote-control where possible.
- Provide warm clothing and warm rest areas; cold increases HAVS risk.
- Introduce health surveillance (baseline and annual) for vibration and audiometry.
- Train workers on early symptoms and reporting; offer smoking-cessation support.
Evaluate: repeat HAV and noise measurements, check trigger times, and audit maintenance. PPE alone is not a control programme.
3. What should be done about the worker with diagnosed early HAVS and the two with hearing changes?
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Diagnosed early HAVS
- Refer to occupational health for assessment and advice; keep the worker under health surveillance.
- Adjust duties to keep vibration exposure well below the action value, not just below the limit; consider redeployment.
- Explain the diagnosis, prognosis and reporting duties; maintain confidentiality.
Hearing changes
- Repeat audiometry after a rest period to exclude temporary threshold shift; refer for specialist assessment if confirmed.
- Review noise exposure and protection; ensure the worker is not exposed above the limit.
- Record as a reportable occupational disease if the criteria are met.
Organisation
- Review the risk assessment and control programme; do not blame the workers. Report the HAVS case and hearing loss through the correct channel, and use them as leading evidence for prevention.