Ethylene oxide (oxirane) is classed as a non-threshold genotoxic carcinogen with no Workplace Exposure Limit from 1 December 2026. Until 30 November 2026 the current exposure standard is still the numeric reference. The changes list leaves both the old standard and any new limit blank for this row. Do not invent a December figure, and do not copy a number into the report from memory. If a pre-December report needs the exposure standard, quote it from the site’s list and footnote that document.
Confirm commencement with the WHS regulator. Absence of a limit after December is not absence of a duty.
Two reporting periods, written differently
Through 30 November, personal and area results can support exposure-standard compliance. Name the comparator from the site’s list. Cover load and unload, aeration, cylinder change, maintenance and the equipment supplier’s technicians.
From 1 December, once the change is in force, there is no EtO limit on this row to report “compliance” against. The same measurements can still describe control performance and residual gas. Say that in the title of the table. Do not add a short-term limit so the slide has a number.
What to sample on a steriliser
Door-open minutes and aeration staging usually dominate residual gas. Sample those tasks on a production load mix. An empty-chamber validation day will not stand in for a full load.
Cylinder and manifold work, scrubber and duct entry, and after-hours technicians are separate tasks even when day-shift operators look controlled. Adjacent staff who are not trained on ethylene oxide belong in the map when they can be in the room.
Record load class, door-open minutes, whether aeration was running, alarm history, and what respiratory protection was worn. Those notes explain the result. They are not a substitute for a limit.
How to file the hierarchy next to the numbers
The client brief should say, in ordinary sentences, that no December limit will be invented and that any exposure-standard figure used before 1 December comes from the site list.
Read the elimination and substitution record alongside the air data. If EtO use remains, the report should say what was considered and why it was not practicable, then whether door capture, aeration and exhaust were checked on real loads. Administrative rules and respiratory protection come after that evidence, not instead of it.
Keep this survey out of glutaraldehyde and other cold-sterilant files. Do not reuse language from chromium (VI) or vinyl chloride packs. The duty shape may look similar. The plant does not.
Reading the numbers
While the exposure standard still applies, state the limit of detection against that standard. A non-detect with a high detection limit is weak evidence. Residual peaks at door-open should be reported for control diagnosis even when a shift average looks low.
After 1 December, do not convert those diagnostics into a limit you made up. Label the survey as evidence of minimisation so far as reasonably practicable.
Stopping the exposure-standard programme early, because “the change is coming,” leaves a gap through November. Treating a chamber specification sheet as a capture test leaves a gap in the engineering file.
Before you mobilise
Confirm the change class with the client in plain language: no limit from 1 December 2026; eliminate or minimise so far as reasonably practicable; current exposure standard until 30 November 2026. Confirm the source document for any pre-December number. Confirm load, unload, aeration and maintenance are in scope. Confirm the report will not be merged with a cold-sterilant programme.
Sources
- Safe Work Australia, *Changes to Workplace Exposure Limits – May 2025*: https://www.safeworkaustralia.gov.au/sites/default/files/2025-05/changes_to_workplace_exposure_limits_-_may_2025.pdf
- Safe Work Australia, changes between exposure standards and exposure limits: https://www.safeworkaustralia.gov.au/safety-topic/managing-health-and-safety/workplace-exposure-limits-airborne-contaminants/changes-between-wes-and-wel
Next step
Occ Hygiene can structure exposure-standard evidence through 30 November and task surveys after that date that do not invent a December limit.
