The workplace exposure limits mining WA operators must meet replace the old workplace exposure standards on 1 December 2026. WorkSafe has confirmed that the updated limits for dust, fumes, gases, vapours and fibres apply across Western Australia from that date. The monitoring, record keeping and exceedance duties in the Work Health and Safety (Mines) Regulations 2022 do not change, but the numbers your monitoring program is measured against do, and several of them are much lower.
This guide covers the values that matter most at a mine, the monitoring regulations, the immediate notification duty when a limit is exceeded, the mine air quality officer, and what to check in the program before 1 December.
What actually changes on 1 December 2026
Safe Work Australia reviewed the national workplace exposure standards (WES) and work health and safety ministers agreed two things: a change of name to workplace exposure limits (WEL), and a revised list of values. Safe Work Australia’s document Changes to Workplace Exposure Limits: Effective from 1 December 2026 sets out every value that is new or changing. Up to 30 November 2026 the WES list applies; from 1 December 2026 the WEL list applies.
In Western Australia, WorkSafe’s page on workplace exposure standards or limits says that until 1 December 2026 you must still comply with the WES list. WorkSafe’s mining statement, Updated limits to safeguard mine workers from airborne hazards (last updated 6 October 2026), states that from 1 December 2026 the updated limits apply across Western Australia.
One point of detail for anyone reading the legislation closely. The Work Health and Safety (Mines) Regulations 2022, in the version current as at 15 May 2026, still define “exposure standard” by reference to the Workplace Exposure Standards for Airborne Contaminants. The 1 December date in this article rests on WorkSafe’s published statements, which are the regulator’s position. The duties themselves are the same either way.
The values that matter most at a mine
Most of the changes are industrial chemicals that few mines handle. A handful sit right in the middle of mining and mineral processing:
- Diesel particulate matter is a new entry on the national list, at 0.01 mg/m3 (8-hour TWA) as respirable elemental carbon. WA underground mines already have a diesel particulates standard in regulation 656B of the Mines Regulations: 0.1 mg/m3 (TWA) measured as sub-micron elemental carbon. WorkSafe’s published material does not yet say how the two figures will sit together, so an underground operation should confirm its position with WorkSafe. Any site running diesel equipment in a pit or a workshop also needs to know where it stands against the new figure.
- Carbon monoxide drops from 30 ppm to 20 ppm (8-hour TWA).
- Sulphur dioxide changes form as well as value. The WES has an 8-hour TWA of 2 ppm and a short-term exposure limit (STEL, 15 minutes) of 5 ppm. The WEL has no 8-hour TWA, only a STEL of 0.25 ppm. Short peaks now matter more than the shift average, which affects how you sample. Roasting, smelting and sulphide ore processing are the obvious places to look.
- Manganese moves from separate WES entries for dust and compounds (1 mg/m3 TWA) and fume (1 mg/m3 TWA, 3 mg/m3 STEL) to one WEL entry for fume, dust and compounds (as Mn), with 8-hour TWA limits of 0.1 mg/m3 inhalable and 0.02 mg/m3 respirable. WorkSafe’s mining information sheet names manganese compounds, sulphur dioxide and welding fumes as examples.
- Respirable crystalline silica does not change. It is not in Safe Work Australia’s list of changed values, so it stays at 0.05 mg/m3 for an eight-hour shift, the figure WorkSafe already quotes.
Check your own substances against the full WEL list, not this summary. A mine whose program was built around silica alone may now have contaminants that were comfortably compliant under the WES and are not under the WEL.
Carcinogens that lose their number
WorkSafe notes that for 33 chemicals classified as non-threshold genotoxic carcinogens there will no longer be a WES or WEL from 1 December 2026. Chromium VI compounds are among the examples given, which matters wherever stainless steel is welded. No number does not mean no duty: regulation 635A still requires the concentration of any airborne contaminant at a mine to be as low as is reasonably practicable.
What the Mines Regulations require, and what stays the same
The legal structure is unchanged by the WEL switch. Six provisions do the work.
Regulation 49: the limit must not be exceeded
The mine operator must ensure that no person at the mine is exposed to a substance or mixture in an airborne concentration above its exposure standard. The maximum fine for a body corporate is $35,000. Where a substance or mixture has no exposure standard, regulation 49(2) sets default 8-hour TWA limits for airborne dust of it: 3.0 mg/m3 respirable and 10.0 mg/m3 inhalable.
Regulation 635A: as low as reasonably practicable
The limit is a ceiling, not a target. Regulation 635A requires the concentration of any airborne contaminant, including asphyxiant and explosive gases, to be as low as is reasonably practicable. It names the preferred controls: suppression, or a ventilation or exhaust extraction system, so far as reasonably practicable, and other suitable means only where those are not.
Regulations 50 and 637: when and how to monitor
Under regulation 50, the operator must monitor if it is not certain on reasonable grounds whether a concentration exceeds the standard, or if monitoring is needed to decide whether there is a risk to health. Regulation 637 adds the mining layer: monitoring must be carried out by, or under the supervision of, a mine air quality officer (or, for underground parts, a mine air quality officer or underground ventilation officer), at a frequency that reflects the risk of a contaminant exceeding its standard.
Records kept for 30 years
Regulation 50(2) requires monitoring results to be recorded and kept for 30 years. Regulation 637(2) says what the record must contain: the results, the dates, location and frequency of the monitoring, and the sampling method and equipment used. Regulation 50(3) requires results to be readily accessible to people at the mine who may be exposed.
Regulations 638 and 639: devices and signs
Monitoring devices must be suitable for the monitoring and the substance, positioned to work to best effect, and maintained and calibrated. Where devices produce warnings, signs must explain what the warning means and what people must do when it goes off.
When a limit is exceeded: regulation 637A
This is the duty most likely to catch a site out once lower limits apply. If a substance or mixture at a mine is in an airborne concentration above its exposure standard, regulation 637A requires the mine operator to immediately notify:
- any affected workers or other persons at the mine, and
- the regulator.
The operator must then take steps to bring the concentration back below the standard, and have monitoring carried out again as soon as practicable after those steps, by or under the supervision of a mine air quality officer (or underground ventilation officer for underground parts). The maximum fine for a body corporate is $21,000 for each of the two subregulations.
WorkSafe’s guidance on mine air quality sampling and assessment describes the reporting route: the mine air quality officer submits sample results to the mine worker exposure database on the Safety Regulation System (SRS), and submits an exceedance investigation report and action plan to the same database.
An exceedance notification under regulation 637A is a separate duty from notifiable and reportable incidents. A single result can trigger one without the other. The incident regime is explained in our guide to notifiable and reportable incidents at WA mines.
A site that has never run that sequence for a contaminant other than silica should rehearse it before December.
The mine air quality officer
Schedule 26 clause 4 requires a mine air quality officer (MAQO) to be appointed if a hazard identified under the mine safety management system includes exposing workers to airborne contaminants, heat or humidity. The officer’s functions are to advise the mine operator or site senior executive on reducing exposure, to plan and carry out monitoring by reference to the risk at the mine, and to report the results.
To be eligible, a person must complete a regulator-approved course on sampling and assessing airborne contaminants, an approved WHS risk management unit for mine air quality officers, and the applicable legislation examination. WorkSafe also expects the officer to communicate findings to site management and results to frontline personnel.
The WEL change adds work to this role. A MAQO whose sampling plan was built around a few contaminants now has to re-rank everything against new numbers, and may need different sampling methods for contaminants such as diesel particulate measured as elemental carbon. How the MAQO fits alongside the other appointments is covered in our article on the mine safety management system.
What to change in the monitoring program before 1 December
WorkSafe’s information sheet for mining, Workplace exposure limit: new limits take effect from 1 December 2026, sets out five actions: identify, assess, control, document and review. Translated into a site senior executive’s to-do list:
- Rebuild the contaminant inventory. List every airborne contaminant generated or used on site, from blasting fumes and diesel exhaust to processing reagents and welding fume, and check each one against the WEL list rather than the WES.
- Re-read the existing data. Compare past sampling results with the new limits. A result that sat at half the old standard can be well over the new one.
- Re-set the sampling plan. Regulation 637 ties frequency to risk. Similar exposure groups that now sit close to a limit need more frequent sampling, new contaminants need a method, and a limit set only as a STEL, such as sulphur dioxide’s, needs short-duration sampling rather than a full-shift average.
- Fix the controls where the gap shows. Apply the hierarchy of controls, starting with suppression, ventilation and extraction as regulation 635A requires, and keep respiratory protection as the last line.
- Update the documents. WorkSafe lists the health management plan, the sampling schedule and compliance records such as RPE fit testing, health monitoring and training, and notes that inspectors may ask for them. Regulation 675EA is the duty to prepare and implement the health management plan.
- Check the exceedance procedure. Make sure the regulation 637A sequence works for every contaminant, names who notifies the regulator, and does not wait for a monthly report.
- Revisit extended shifts. Limits are based on an eight-hour day. WorkSafe’s adjustment of atmospheric contaminant exposure standards guide covers adjustment for longer rosters, though WorkSafe flags it as under review to align with regulation 49.
Where airborne contaminants reach the level of a principal mining hazard, the controls belong in the principal mining hazard management plan as well. Our guide to the principal mining hazard management plan in WA explains how that plan is put together.
Where air monitoring programs fall down
- Silica tunnel vision. The program measures respirable dust and silica well and nothing else. That gap widens on 1 December, when diesel particulate, sulphur dioxide and manganese have tighter or new limits.
- Results that live in a lab report. Regulation 50(3) asks for results to be readily accessible to exposed people. A PDF in the hygienist’s inbox does not meet that.
- Exceedances handled as routine. A result over the limit is filed with the monthly summary. Regulation 637A says the regulator is told immediately.
- Controls nobody owns. The sampling report recommends more water on the haul road or a ventilation change, and six months later no one can say whether it happened.
- Records that cannot be found in 30 years. Sampling data on a contractor’s system or a personal drive rarely survives a change of provider.
For the quarry side of the same problem, including where silica exposure comes from at a face and a crushing plant, see our guide to silica dust at WA quarries.
Keeping the controls and the record trail together
HazView does not sample air. The sampling, the instruments and the laboratory analysis stay with the MAQO and the hygiene provider. What breaks down at most sites is everything around the numbers: knowing where the exposure areas are, whether the agreed controls were actually put in, and finding the inspection records when an inspector asks.
In HazView, dust and air quality hazard areas are drawn on one interactive map of the site that every role uses, with their type, status, photos and full history. Each hazard can carry controls with an accountable owner, a due date and a status, so a recommendation from a sampling report becomes a tracked action rather than a line in a PDF. Inspections of suppression systems, ventilation or extraction can be built as the site’s own checklist forms, completed offline in the field and pinned to the place they were done, with a PDF record emailed on submit. The hazard register exports with one click to CSV or JSON, and each site’s records stay private inside its own dedicated deployment.
For the wider WA picture, start with our guide to quarry safety in Western Australia. To see how site leaders use the map to track controls, read HazView for site managers, or book a demo with your own hazard and inspection forms.
Summary: airborne contaminant duties at WA mines
| Duty | Source | What it requires | Changes on 1 Dec 2026? |
|---|---|---|---|
| Do not exceed the limit | r 49 | No person exposed above the exposure standard; default dust limits where none exists | The values change to the WEL list |
| As low as reasonably practicable | r 635A | Suppression, ventilation or extraction first | No |
| Monitor where uncertain | r 50(1), r 637(1) | By or under a MAQO (or UVO underground), risk-based frequency | No, but the risk ranking will |
| Keep records | r 50(2), r 637(2) | Results, dates, location, frequency, method and equipment, kept 30 years | No |
| Make results accessible | r 50(3) | Readily accessible to people who may be exposed | No |
| Devices and signs | r 638, r 639 | Suitable, positioned, maintained, calibrated; signs explain warnings | No |
| Exceedance response | r 637A | Immediately notify workers and the regulator, reduce, re-monitor | More results may trigger it |
| Mine air quality officer | Sch 26 cl 4 | Appointed where airborne contaminants, heat or humidity are an identified hazard | No |
Frequently asked questions
When do workplace exposure limits apply at WA mines?
From 1 December 2026. WorkSafe has stated that the updated limits apply across Western Australia from that date, and that until then mines must still comply with the workplace exposure standards (WES) list.
Is the respirable crystalline silica limit changing?
No. Respirable crystalline silica is not in Safe Work Australia’s list of values changing on 1 December 2026, so it remains 0.05 mg/m3 as an eight-hour time-weighted average.
Do we have to tell the regulator about every exceedance?
Yes. Under regulation 637A of the Work Health and Safety (Mines) Regulations 2022, the mine operator must immediately notify affected workers and the regulator when an airborne contaminant exceeds its exposure standard, then reduce the exposure and re-monitor. WorkSafe’s guidance has the MAQO submit results and an exceedance investigation report and action plan to the mine worker exposure database in SRS.
Does every WA mine need a mine air quality officer?
A MAQO must be appointed if a hazard identified under the mine safety management system includes exposing workers to airborne contaminants, heat or humidity. Air monitoring under regulation 637 must be carried out by or under the supervision of a MAQO, or an underground ventilation officer for underground parts.