Diesel Exhaust Particulate Matter — New Workplace Exposure Limit

CAS: 9000-49-7 | Notation: Respirable fraction, carcinogen (IARC Group 1)

Current WES

None

mg/m³

New WEL (Dec 2026)

0.1

mg/m³

Change

NEW limit (no previous WES)

reduction

Health Effects

Diesel engine exhaust was classified as a Group 1 carcinogen by IARC in 2012, with sufficient evidence of causing lung cancer in humans and limited evidence of an association with bladder cancer. The carcinogenic risk is attributed to the particulate matter component, which consists of a carbonaceous core with adsorbed polycyclic aromatic hydrocarbons, nitro-PAHs, and other organic compounds. Beyond carcinogenicity, diesel particulate matter causes respiratory inflammation, decreased lung function, and exacerbation of existing asthma and chronic obstructive pulmonary disease. Cardiovascular effects including increased risk of heart attack and stroke have been demonstrated in epidemiological studies of diesel-exposed workers. The ultrafine particles in diesel exhaust penetrate deep into the alveolar region of the lungs and can translocate into the bloodstream, contributing to systemic inflammatory responses.

Where Exposure Occurs

Underground mining operations using diesel-powered equipmentTunnelling and underground construction worksEnclosed warehouses and distribution centres with diesel forkliftsBus and truck depots and maintenance workshopsUnderground car parks with diesel vehicle trafficConstruction sites with diesel plant in poorly ventilated areas

What to Do Now

01Conduct baseline diesel particulate matter monitoring at all workplaces where diesel-powered equipment operates in enclosed or poorly ventilated spaces. Because no WES previously existed in Australia, most workplaces have never measured DPM levels. Monitoring should prioritise underground operations, enclosed warehouses, and workshops where diesel vehicles idle or operate for extended periods.

02Assess fleet composition and develop a transition plan for replacing older diesel equipment with Tier 4/Stage V compliant engines, electric alternatives, or LPG-powered equipment. Electric forklifts, battery-electric underground loaders, and hybrid diesel-electric trucks can eliminate or substantially reduce DPM emissions at the source. Where diesel equipment must be retained, diesel particulate filters rated to remove at least 90 per cent of particulate matter should be retrofitted.

03Upgrade ventilation systems in enclosed workspaces where diesel equipment operates. Underground mines must review primary and secondary ventilation systems to ensure sufficient dilution airflow at the working face. Warehouses should install mechanical ventilation systems that provide a minimum of 6 air changes per hour in areas where diesel forklifts operate. Vehicle maintenance workshops require dedicated exhaust extraction systems at each service bay.

04Implement administrative controls including engine idle-time limits, restricting diesel equipment operation to well-ventilated areas, and scheduling diesel-intensive tasks to minimise the number of workers in the exposure zone. Route planning in warehouses and underground operations should minimise diesel equipment operating time in areas where other workers are present.

05Establish health surveillance for workers with regular diesel particulate exposure including baseline and periodic lung function testing, chest imaging at intervals determined by the occupational physician, and respiratory symptom questionnaires. Given the IARC Group 1 carcinogen classification, health surveillance records must be retained for 40 years and workers must be informed of their individual monitoring results.

Monitoring Method

Personal air sampling using a calibrated pump at 1.5 to 2.2 L/min with a respirable cyclone pre-selector and quartz fibre filter. Analysis for elemental carbon by thermal-optical analysis (NIOSH Method 5040). Submicron impactor samplers can provide size-selective sampling that better represents the health-relevant fraction. Real-time monitoring with photometric instruments provides complementary data for identifying peak exposure tasks.

Affected Industries

Construction →

Measure exposure against the right limit

OH Consultant designs and runs personal exposure monitoring for diesel particulate matter, reviewed by a Certified Industrial Hygienist, and reports results against the limit that applies to your site, whether the 1 December 2026 WHS WEL or a mine-specific limit.

Request a sampling proposal