Australia now has a national workplace exposure limit for Diesel Particulate Matter (DPM), a known carcinogen that many Australian workers are exposed to. From 1 December 2026, a limit of 0.01 mg/m3 (measured as respirable elemental carbon, averaged over eight hours) applies as part of the new national workplace exposure limits. This follows the mining industry in several states, including New South Wales, introducing its own exposure standard.
What is Diesel Particulate Matter?
Diesel Particulate Matter (DPM) consists of fine particles that together with gases make up Diesel Engine Exhaust (DEE). Essentially, DPM is soot (carbon particles) that other substances can stick to, including carcinogens like polycyclic aromatic hydrocarbons (PAH).
According to the Cancer Council, more than one million Australians per year are exposed to diesel exhaust in their workplace. This makes diesel the second most common workplace carcinogen after UV radiation. DPM exposure has been shown to increase the risk of lung cancer, and may also be linked to an increased risk of bladder cancer.
Exposure level advice from the AIOH
For many years there was no national workplace exposure standard for diesel particulate matter – only exposure standards for some of the individual elements of diesel exhaust.
As awareness of DPM-related illness has grown, there has been increasing discussion of the possibility of introducing an exposure standard. In 2017, the Australian Institute of Occupational Hygienists published a position paper summarising the evidence and giving advice on the assessment, evaluation and control of DPM exposure.
In particular, the AIOH has the following advise on recommended exposure levels. (’EC’ is elemental carbon, the main constituent of DPM):
Notwithstanding the lack of a well-defined universal dose response relationship, experience has shown that when workplace exposures are controlled below 0.1 mg/m3 DPM (measured as submicron EC), irritant effect decreases markedly. In the absence of any more definitive data, the AIOH supports the maintenance of DPM levels (measured as submicron EC) as low as reasonably practicable (ALARP) below an 8-hour TWA [time-weighted average] guidance exposure value of 0.1 mg/m3, with the provision of applying a TWA value of 0.05 mg/m3 as an action level which triggers investigation of the sources of exposure and implementation of suitable control strategies.
Before the national limit was set, many occupational hygienists, including Airsafe, used the AIOH’s recommendations as a guideline in monitoring exposure levels to DPM.
In several states including New South Wales, the mining industry has adopted the 0.1 mg/m3 time-weighted average measure as an industry-specific exposure standard.
The national exposure limit
Following a consultation that began in 2023, Safe Work Australia settled a national workplace exposure limit for DPM of 0.01 mg/m3, measured as respirable elemental carbon over an eight-hour average, taking effect on 1 December 2026 as the workplace exposure standards become workplace exposure limits. The NSW mining standard (0.1 mg/m3) continues to apply to mines and petroleum sites.
In its submission to the consultation, the Australian Institute of Occupational Hygienists supported the principle of a national exposure standard, while making several criticisms of the review’s methodology and conclusions.
With the new limit approaching, it’s important for anyone in charge of a workplace that uses diesel-powered machinery to be aware of their legal obligations, and to minimise their workers’ exposure to DPM as much as possible. For the current position and what the new limit means for your workplace, see our diesel particulate monitoring page.
How Airsafe can help
Airsafe offers expert risk assessment and monitoring for workplace DPM exposure. If your business uses diesel, don’t put your workers at risk: call Airsafe on 1300 888 338.
