On 1 December 2026, Western Australia moves from workplace exposure standards (WES) to workplace exposure limits (WEL) for airborne contaminants and their monitoring.
Importantly for one of WA’s most hazardous contaminants, respirable crystalline silica (RCS), the number does not change: the exposure limit stays at 0.05 mg/m³ as an eight-hour time weighted average (TWA). What changes is the framework around it, the values for many other substances on your site and the attention regulators are giving to air monitoring in the lead-up.
Everything that’s changing on 1 December 2026
Safe Work Australia’s Workplace exposure limits for airborne contaminants (the WEL list) replaces the WES list nationally from 1 December 2026 (subject to each jurisdiction adopting it into its own laws). Until 30 November 2026, you must keep exposures below the current WES. From 1 December, you must keep them below the WEL.
WorkSafe WA has confirmed the transition is effective from December 1 2026 in Western Australia and covers every WA workplace where workers may breathe in dust, fumes, gases or vapours. It names mining, agriculture, construction, manufacturing, cold storage and automotive as the industries most likely to be affected. NOPSEMA has issued similar guidance for offshore petroleum operators.
Values for most contaminants carry over unchanged. Others see one of three kinds of change:
- The values were either lowered or raised
- 31 airborne contaminants that had no national limit were added to the new WEL
- Carcinogens classed as non-threshold genotoxic lost their numerical limits, because no safe level of exposure can be set. Exposure to these must now be eliminated or minimised so far as is reasonably practicable.
The most critical of the 31 new additional is diesel exhaust. From 1 December, diesel particulate matter will have an exposure limit of 0.01 mg/m³, measured as respirable elemental carbon. This will demand additional monitoring on many WA projects.
Workplace exposure standard vs workplace exposure limit
Although the name has changed, your legal duty remains the same. Under WHS regulations, a person conducting a business or undertaking (PCBU) must ensure no one at the workplace is exposed above the listed value and must still eliminate or minimise exposure so far as is reasonably practicable, even when results sit under that value.
The change is in how the number reads. While a “standard” was often read as a target or guide, a “limit” makes it clear the value is a ceiling that must not be exceeded. WorkSafe WA describes a WEL as the maximum airborne concentration most people can be exposed to without harm to their health.
In practice, the renaming gives no new room to argue that a result “close to the standard” is acceptable. A result above the WEL is a breach, plain and simple.
Does the silica exposure limit change in December?
No. While, like other contaminants, RCS shifts from having a “standard” to a “limit”, the value itself remains at 0.05 mg/m³ (8-hour TWA) from 1 December 2026.
There was a proposal to halve the limit to 0.025 mg/m³ and RCS was held back from the main decision in 2024 to allow for further research into the proposed limit. Safe Work Australia published the Decision Regulation Impact Statement in June 2026 and a majority of ministers did not support a change to the value. As a result, the RCS WEL remains at 0.05 mg/m³.
However, changes have been made to other chemicals under review – proof that regulations are ever-changing and that site managers need to keep their ears to the ground.
What WA employers need to do before 1 December
Just because silica numbers are unchanged does not mean there is nothing to do. WorkSafe WA’s guidance for the transition asks workplaces to:
- Review the chemical inventory and identify substances whose values have changed or been added (the national Hazardous Chemical Information System lists current values)
- Review control measures such as substitution, isolation, ventilation, engineering controls and respiratory protection
- Conduct air and health monitoring where exposures may occur, engaging an occupational hygienist where specialist advice is needed
- Update risk assessments, safety data sheets and safe work procedures
- consult workers about any changes to their work.
For silica specifically, check these four points:
- Your monitoring data is current: If your last personal sampling round is more than a year old, or the process, materials or controls have changed since, the results no longer describe today’s exposures. Our airborne contaminant monitoring uses personal samplers in the worker’s breathing zone, so results can be compared directly against the WEL.
- Your results are adjusted for shift length: The 0.05 mg/m³ limit assumes an eight-hour day and a five-day week. Long shifts give the lungs less recovery time, so the value is adjusted downwards. Using the Brief and Scala model referenced in national interpretation guidance, a 12-hour shift brings the adjusted RCS value to about 0.025 mg/m³. For FIFO rosters and 12-hour shifts, an unadjusted result can look compliant when it is not.
- You know what happens when a result exceeds the limit: WA’s Work Health and Safety (General) Regulations require you to notify WorkSafe as soon as reasonably practicable, and within 14 days, when air monitoring shows RCS above the exposure limit.
- Your respiratory protection is matched to your results: Fit testing and the right class of respirator matter as much as the number on the report, so ensure your staff are using equipment with a protection factor matched to their work. And remember, respirators remain the last line of defence after elimination, substitution and engineering controls.
How we help WA sites prepare for the WEL
We run occupational hygiene programs across Western Australia for mining, construction, civil and industrial clients. We’re assisting site and project managers in navigating the WES to WEL transition by:
- Reviewing your existing crystalline silica monitoring results against the WEL, including shift adjustment
- Designing and running personal and static sampling for RCS, diesel particulate matter and other contaminants with changed or new limits
- Setting up health monitoring and health management plans for workers at risk
- Respirator fit testing
- Reporting written to stand up to a WorkSafe inspection.
We mobilise across WA, including regional and remote sites and work alongside your management and environmental teams from system design through to compliance management.
Arrange a consultation today
If you want to confirm where your site stands before 1 December, contact us to arrange a monitoring review.
Our team are ready to mobilise state-wide to design, install and run airborne contaminant monitoring systems.