But-2-yne-1,4-diol WEL 0.5 mg/m³: PCBU checklist before Australia’s Dec 2026 switch

Why HSE and ops should care

But-2-yne-1,4-diol (2-butyne-1,4-diol) is a new airborne contaminant with an 8-hour WEL of 0.5 mg/m³. WES remains the reference until 30 November 2026; WEL applies from 1 December 2026 once implemented. Check your WHS regulator.

Where airborne risk shows up

• Fine chemical manufacture, electroplating and formulation.
• Bag tipping, weighing, milling, blender loading and solution charging.
• Filter change, reactor clean-down, laboratory, maintenance and waste.

SEG and register checklist

Name the substance and synonyms on the hazardous chemical register. Map make-up/weigh, dose/sample, filter, maintenance, lab and clean-down SEGs, including contractors. Check SDS, permits, spill procedures, historical monitoring and who owns enclosure before RPE.

Controls and monitoring

Prefer pre-dissolved or closed-charge feeds. Use enclosed or booth tipping, LEV at weigh/dissolve, covered tanks, maintained collectors and wet/HEPA housekeeping. Commission personal samples that state the analyte, fraction and comparison to 0.5 mg/m³; cover tip, dissolve, filter change and clean-down; report useful LOD/LOQ. Generic dust mass alone is not analyte compliance. Use RPE and gloves as parallel controls.

Prepared before 1 Dec 2026

Show a current register and SDS, task-linked SEG map, monitoring plan/results, verified controls and training that names airborne risk. Do not invent ppm conversions or a STEL for this listing.

Sources

Safe Work Australia WEL changes · SWA WEL/WES changes