But-2-yne-1,4-diol is listed as a new airborne contaminant with an 8-hour WEL of 0.5 mg/m³. WES remains the reference until 30 November 2026; from 1 December 2026 WEL applies once implemented—confirm with the WHS regulator. Do not invent ppm or a STEL.
Characterise the aerosol
Powder handling (bag tip, weigh, blend and mill) is primarily particulate. Solution/bath work may create mist or splash aerosol. Secondary dust can come from settled residue, filter change, maintenance and dry spills.
SEGs and sampling
- Make-up/weigh operators and line dose/sample crews.
- Filter change, maintenance, laboratory and clean-down/waste crews.
Define the fraction explicitly and agree analyte-specific media, recovery, storage and reporting limits with the laboratory relative to 0.5 mg/m³. Collect representative full-shift personal samples plus task samples at tip and dissolve points. Document flow, blanks, LEV, wet/HEPA housekeeping, RPE and LOD/LOQ. Static samples are diagnostics, not personal WEL comparison.
Interpretation and controls
Compare TWAs to 0.5 mg/m³; a high-LOD non-detect is not comfort. Time-weight intermittent tasks with assumptions stated. Prefer pre-dissolved or closed feeds, enclosed tip booths and LEV, covered dosing, wet/HEPA clean-up and disciplined filter changes; use RPE and compatible gloves last.
