On 1 December 2026 the workplace exposure limits (WEL) list replaces the workplace exposure standards. It includes a limit for diesel particulate matter (DPM): 0.01 mg/m³ as an 8-hour time-weighted average, measured as respirable elemental carbon. PCBUs must ensure no one at the workplace is exposed above it.
If your site runs diesel plant, here’s a checklist built from Safe Work Australia’s June 2026 guide, Managing the risks of exposure to diesel engine emissions in the workplace.
1. List your diesel sources
Start with everything that burns diesel. The guide lists heavy vehicles like trucks, buses, trains, tractors, ships, loaders, forklifts and bulldozers. It also includes stationary power sources like generators and winch motors, including those mounted to vehicles.
Don’t stop at the obvious plant. Check for the generator behind the workshop and the service truck with a vehicle-mounted winch.
2. Map who works near them, and for how long
For each source, note where it runs and who is nearby. Include the people who don’t operate the plant, such as dock hands, pickers and mechanics.
The guide notes that levels of exposure can be higher in enclosed, poorly ventilated areas. Loading docks with the doors shut, maintenance bays and underground areas deserve the closest look.
Time matters too. The limit is an 8-hour time-weighted average, so a worker who spends most of a shift near running plant is in a different position from one who passes through.
3. Start controls at the source
The guide says eliminating sources of diesel exhaust is the best option.
If elimination isn’t reasonably practicable, work down the order: substitution, isolation and engineering controls. The guide covers options such as sealed, pressurised cabins with a HEPA-filtered air supply, separating the area where engines run, ventilation and diesel particulate filtration.
On ventilation, the guide says local exhaust ventilation captures diesel exhaust as close to the source as possible. General ventilation is not as effective, because it doesn’t control the hazard at the source. Design of effective ventilation is a skilled area and should be done by someone competent.
4. Back them with administrative controls
Once higher-order controls are in place, the guide lists administrative controls that help. These include:
- switching engines off rather than leaving them idling
- limiting the number of machines running at once
- scheduling work to keep people away from operating plant
- rotating jobs.
Keep up maintenance and emissions testing on engines and ventilation systems. A poorly tuned engine or a blocked filter changes the picture quickly.
5. Decide what gets measured
DPM is used as an indicator for diesel exhaust. The guide says there’s no single exposure limit for diesel engine emissions as a whole, because the composition varies with factors such as engine type, fuel type and operating conditions.
So, depending on the level of risk and the controls in place, you may also need to measure nitrogen dioxide, carbon monoxide and aldehydes such as formaldehyde. The guide says this should be considered as part of the risk assessment.
6. Book monitoring where you can’t be reasonably certain
Under regulation 50(1) of the model WHS Regulations, air monitoring is required if you’re not certain on reasonable grounds whether the exposure standard (the exposure limit from 1 December) is exceeded, or if it’s necessary to determine whether there’s a risk to health.
Safe Work Australia’s Guide for PCBUs: Air monitoring and the workplace exposure limits for airborne contaminants recommends engaging a competent person, such as an occupational hygienist, to design and undertake the monitoring. It also says best practice is to implement controls before monitoring.
When results come back, the guide gives more than half the limit (often called the action level) as an example of when to review your controls. The diesel guide lists DPM approaching the limit, such as above half of it, as a reason to review.
7. Check whether health monitoring applies
Health monitoring may be needed for some workers. But it’s not a control, and it can’t be used in place of control measures. Treat it as a check on whether exposure is affecting workers’ health, not a substitute for controls.
Under the limit is the start
Getting under 0.01 mg/m³ is the minimum. Safe Work Australia is clear that exposure limits aren’t a target or safe level. The duty is still to keep exposure as low as reasonably practicable.
Diesel engine emissions are carcinogenic, which is why the limit is a floor for action.
Before you book anything
Step 2 is easy to skip. A site can know its plant well and still not have timed how long people actually spend near it.
Anitech’s occupational hygienists can help with diesel risk assessments, monitoring design and control reviews ahead of 1 December. Contact Anitech to book a site walk before 1 December.
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