Ventilation and Dust in a School Workshop
A school technology workshop runs timber and acrylic projects. The dust extraction system is a 1.5 kW unit ducted to the saw bench, thicknesser and sander, but the sander's flexible hose is torn and the thicknesser has been moved so its duct now runs 6 m with two right-angle bends. Students report visible dust haze after sanding and a smell of hot plastic when acrylic is cut on the scroll saw. A teacher has developed a cough. The workshop has one 1.2 m wide window that opens and a roller door kept closed in winter. The faculty has $4,000 for improvements and a facilities manager who says the extraction unit 'meets the standard because it was installed by a contractor'.
1. Assess the work health and safety and environmental risks and rank them.
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Ranking by likelihood and severity:
- Respirable wood dust (highest). Visible haze means fine dust is escaping capture. Wood dust is a known respiratory hazard and a carcinogen; the teacher's cough is a warning sign. The torn hose and the long, bent duct reduce airflow at the thicknesser, so extraction is inadequate at the point of generation.
- Acrylic fume. The hot-plastic smell indicates the scroll saw is melting rather than cutting, producing fumes. This needs correct blade speed and feed, plus local exhaust ventilation, not just general ventilation.
- General ventilation. One window and a closed roller door in winter gives poor air exchange, so any escaped dust and fumes accumulate.
- Housekeeping. Settled dust re-enters the air; no mention of cleaning regime.
The facilities manager's claim is a compliance fallacy: installation by a contractor does not mean the system still performs to standard after modification, and the thicknesser's relocation changed the system's design. The correct approach is to measure airflow and capture at each machine, not to rely on the original installation.
2. Allocate the $4,000 and justify the priorities.
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Priority 1 - restore extraction performance (approx. $600-$900): replace the torn hose, re-route the thicknesser duct to minimise length and bends, and seal joints. This is the cheapest high-impact fix because it addresses the main hazard at source.
Priority 2 - verify performance (approx. $300): engage a competent person to measure airflow and capture velocity at each machine and provide a report. This converts the facilities manager's assumption into evidence and protects the school.
Priority 3 - local exhaust at the scroll saw and sander (approx. $1,500): a dedicated extraction point or downdraft table for sanding, and a small local exhaust hood for the scroll saw, with correct blade and speed settings for acrylic.
Priority 4 - general ventilation and housekeeping (approx. $800): improve cross-ventilation (e.g. a second opening or an extract fan), provide a vacuum with fine filters and a cleaning schedule, and PPE (P2 masks) as an interim measure.
Priority 5 - training and signage (approx. $300): induct students on dust and fume controls, and post machine-specific rules.
Justification: money goes first to source control and verification, because general ventilation and PPE are less effective than capturing dust at the tool. Interim PPE and cleaning protect people while the engineering fixes are installed. The plan should be documented and reviewed, and the teacher's cough referred to the school's health and safety reporting process.