Two stories travel together in WHS channels: everything changes on 1 December 2026, and RCS halves to 0.025. For tunnelling dust programs, both need a clear correction.
WES becomes WEL and new entries appear, including DPM as respirable elemental carbon. But the RCS value remains 0.05 mg/m³ respirable on 1 December 2026. Do not write that RCS becomes 0.025 unless a future jurisdictional instrument actually says so.
What changes and what does not
Until 30 November 2026, apply the current WES regime and manage risk under the applicable WHS laws. From 1 December 2026, use the WEL once implemented by the relevant regulator. The RCS benchmark stays 0.05 mg/m³; the change is terminology and the surrounding register, not an automatic halving.
Design useful tunnelling SEGs
- Roadheader, drill-and-blast and shotcrete crews
- Face support, scaling, mucking and services crews
- Plant operators, traffic control and non-cabin workers
- Maintenance, survey and visitors exposed during dusty tasks
Full-shift monitoring and interpretation
Use respirable dust sampling with a method and size selection suitable for comparison with 0.05 mg/m³. Prioritise personal full-shift samples across representative shifts and SEGs; use static samples for ventilation diagnostics, not as substitutes for personal exposure evidence.
Record task, geology, ground support, water suppression, ventilation state, plant mix, shift duration and respiratory protection. Explain the laboratory method, flow control, blanks, recovery, reporting limit and any 8-hour adjustment. Non-detect results are only useful when the LOQ supports decisions near the WEL.
Controls before RPE
- Eliminate or substitute dusty methods and materials where practicable.
- Use wet methods, local exhaust and enclosed or remote plant.
- Verify ventilation and traffic separation during production.
- Maintain plant and suppression systems, then select and fit-test RPE as residual control.
December readiness checklist
Reissue templates so reports say WEL where required, but keep the numerical statement accurate: RCS remains 0.05 mg/m³ respirable on 1 December 2026. Brief workers and supervisors, update SEG maps, confirm the regulator’s implementation, and retain an evidence pack linking results to controls.
A defensible conclusion states the number of personal full-shift samples, the range and distribution, dominant tasks and conditions, uncertainty and reporting limits, and the hierarchy-ordered actions needed. Repeat sampling after material engineering changes using comparable work conditions.
Key takeaway
December changes the framework language, not the RCS number. Treat 0.05 mg/m³ as a ceiling and use exposure evidence to drive controls well below it.
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