A generic risk assessment in a joinery workshop: dust, noise and the limits of a matrix
A bespoke joinery company employs 12 people in a converted warehouse. Its risk assessment, prepared by a consultant in 2019, is a 40-page matrix covering 'wood dust', 'noise' and 'manual handling'. It rates dust risk as 'medium' and controls it by 'LEV and PPE'. The LEV was installed in 2019, has never been thoroughly examined, and the hood is 30 cm from the saw. Personal air sampling during a busy day gives inhalable hardwood dust of 7.2 mg/m³ as an 8-hour TWA (WEL 3 mg/m³). Noise dosimetry gives 87 dB(A) Lep,d. Two employees have reported persistent coughs; one has had two weeks off. The managing director says the matrix score is 'medium, so we are compliant' and resists stopping work because a kitchen contract is due.
1. Critique the risk assessment and the managing director's claim that a 'medium' matrix score demonstrates compliance.
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Critique
- The matrix assigns 'medium' without measuring exposure. A matrix is a prioritisation tool, not a compliance certificate; it cannot override a WEL.
- 7.2 mg/m³ as an 8-hour TWA is 2.4 times the 3 mg/m³ WEL for inhalable hardwood dust, so compliance is not demonstrated.
- The LEV has never been thoroughly examined; the hood is 30 cm from the saw, likely outside the capture zone. 'LEV and PPE' is not a control narrative.
- There is no evidence of worker involvement, no health surveillance despite coughs, and no review trigger for new symptoms.
- The assessment is generic and does not consider the kitchen contract's changed work pattern.
Conclusion: the 'medium' score is not evidence of compliance. The employer must reassess with competent advice, measure exposure and act on the WEL breach.
2. Prioritise the additional controls using the hierarchy of control, explaining the expected effect on exposure and residual risk.
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Hierarchy of control
- Elimination/substitution: avoid cutting the specific board where possible; pre-cut or buy in components; use a less hazardous material if the specification allows.
- Engineering: enclose the saw, fit on-tool extraction, redesign the hood to the saw, check ducting and airflow, and commission and thoroughly examine the LEV. This is likely to give the largest sustained reduction.
- Administrative: restrict cutting to a designated area, rotate tasks, clean with a vacuum rather than dry sweeping, and display exposure results. Train workers to recognise LEV failure.
- PPE: fit-tested RPE as an interim and last resort, not instead of LEV.
Expected effect: engineering controls should bring exposure below 3 mg/m³; if they do not, stop the task. Residual risk must be ALARP, and sampling should verify performance. Health surveillance for wood dust should be considered for persistent cough.
3. What immediate decision should be made about continuing the kitchen contract, and what factors should inform it?
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Decision Do not continue the kitchen contract using the current method. The employer has actual exposure data above the WEL and two workers with symptoms; continuing would be difficult to defend as reasonably practicable. The contract deadline is a commercial pressure, not a justification.
Immediate steps
- Stop the cutting task; isolate the saw; provide interim controls while engineering changes are made.
- Tell the client honestly and agree a revised programme; consider subcontracting the cutting to a supplier with controlled extraction.
- Refer the symptomatic workers to occupational health and review their duties.
- Verify controls by personal sampling before restart; document the decision and the basis.
- If the director insists on continuing, escalate to the board and record the advice; the regulator may consider an enforcement notice.