When a diesel forklift reverses through a distribution centre, or a heavy rigid truck idles in a loading bay, few managers stop to consider what workers are breathing. Yet these environments—warehouses, 3PL facilities, cold storage depots, and transport terminals—represent some of the most overlooked sources of diesel particulate matter (DPM) exposure in Australian workplaces.
DPM in Warehouses & Transport Depots — Key Facts
- Diesel forklifts operating in enclosed or poorly ventilated warehouses are the primary DPM source for logistics and transport workers in Australia.
- Studies have recorded DPM concentrations of 0.05–0.35 mg/m³ EC in Australian warehouse environments — potentially exceeding the incoming 0.01 mg/m³ WEL.
- Switching from diesel to electric forklifts eliminates DPM at the source, removing the need for ongoing DPM monitoring in warehouse environments.
- Where diesel forklifts remain, a combined approach of area monitoring plus personal monitoring for the highest-exposed workers is the accepted compliance strategy.
- DPM risks in warehouses increase significantly during peak operational periods when fleet utilisation rates — and therefore engine running time — are at their highest.
Sources: Safe Work Australia | WHS Regulations 2017 | Anitech Occupational Hygienists | AIOH Guidance
Unlike outdoor construction sites or mining operations where risks from dust and airborne contaminants like DPM are widely understood, indoor diesel exposure in logistics remains largely invisible. Poorly ventilated warehouse spaces accumulate DPM rapidly. Workers may spend entire shifts in high-concentration zones without any awareness of the hazard. And with Australia’s new DPM workplace exposure limit dropping to 0.01 mg/m³ respirable elemental carbon (REC) from 1 December 2026, the stakes have changed fundamentally.
This guide explains where DPM accumulates in warehouse and transport environments, who is most at risk, and how to implement a monitoring strategy that protects workers and ensures compliance with the new WEL.
The Overlooked Risk: Why Warehouses and Depots Are High-Exposure DPM Environments
Warehouses and transport depots are uniquely vulnerable to DPM accumulation. Here’s why:
Enclosed Spaces with Limited Ventilation
Diesel forklift engines operate in enclosed buildings designed primarily for thermal efficiency, not air quality. Unlike outdoor worksites where exhaust disperses freely, warehouse environments trap exhaust gases and particulates. Poor ventilation compounds the problem. Many warehouses—especially older facilities and temperature-controlled cold stores—rely on minimal air exchange to maintain operational efficiency. In these settings, DPM concentrations can climb well above ambient outdoor levels within hours of forklift operation.
High-Density Equipment Operation
A single warehouse may operate 5, 10, or even 20 diesel forklifts simultaneously during peak periods. This is not sporadic exposure—it is continuous, concentrated emission. Fleet managers rarely consider the cumulative DPM load created by multiple vehicles in a single enclosed space. When three forklifts are stacking pallets simultaneously on opposite ends of a 20,000 m² warehouse, workers in the middle zone are exposed to exhaust from all three units.
Shift Patterns Amplify Exposure
Warehouse workers often complete full 8–10 hour shifts within high-exposure zones. They move continuously through areas where forklifts are active. Area monitoring strategy for warehouses. Unlike construction workers who may work outdoors and move between sites, warehouse staff are trapped in the same enclosed environment. Long-duration exposure multiplies the health risk significantly.
Loading Docks and Idling Vehicles
Loading docks create extreme concentration zones. Trucks back in to load or unload and may idle for 20–30 minutes with engines running. In a poorly designed dock with minimal cross-ventilation, diesel exhaust can accumulate to dangerous levels. Night-shift receiving operations—common in 3PL facilities—often occur in less-supervised conditions where idling controls are not enforced.
Cold Storage Facilities Amplify the Risk
Refrigerated warehouses and cold storage depots present a special case. Tight building envelope design (required to maintain temperature) means virtually no natural ventilation. Diesel-powered counterbalance and reach forklifts operate in these ultra-controlled environments. The combination of enclosed space, high-density equipment operation, and minimal air exchange creates some of the highest DPM concentrations found anywhere in Australian workplaces.
Where DPM Builds Up: Hotspot Mapping in Warehouse & Depot Settings
DPM does not distribute evenly throughout a warehouse. High-concentration zones emerge based on equipment activity, ventilation patterns, and building geometry.
Common Hotspot Zones:
1. Forklift Movement Corridors
Main lanes where forklifts travel repeatedly accumulate DPM. Narrow aisles between racking intensify exposure because exhaust has less distance to disperse. Workers retrieving stock from these aisles face continuous low-level exposure.
2. Stacking and Loading Areas
Zones where forklifts remain stationary (placing pallets, stacking containers, positioning loads) experience elevated DPM. Unlike mobile equipment, stationary operation allows exhaust to accumulate in a confined area.
3. Loading Docks and Truck Bays
These are universally high-concentration areas. Truck engines running while vehicles are parked. Forklift engines operating in confined dock spaces. Minimal ventilation if dock doors are closed. DPM can exceed WEL limits within 30 minutes of sustained activity.
4. Cold Storage Interiors
Highest-risk zones in any facility. Complete dependence on engineered ventilation with minimal air exchange. DPM from forklift engines accumulates rapidly and persists because outdoor air replacement is minimal.
5. Fleet Maintenance and Servicing Areas
Diesel mechanics working in service bays experience intense exposure. Running engines for diagnostics, maintenance operations on fuel systems, and exhaust component repair all generate airborne DPM. These zones often have the poorest ventilation planning.
6. Receiving and Dispatch Areas
24-hour operations compound exposure. Night shifts may have fewer workers but higher equipment density (goods must move quickly). Less supervision means forklift operators may leave engines idling longer.
Understanding Airflow Patterns
Effective hotspot mapping requires understanding ventilation dynamics. DPM concentrations follow airflow. If a warehouse has exhaust fans on one wall and inlets on the opposite wall, high-exposure zones will locate downwind of equipment and upstream of exhaust exits. Corners with minimal airflow become DPM traps.
Area sampling (static monitoring) is particularly valuable in warehouse environments because it reveals these concentration patterns. A series of area samples at different locations identifies genuine hotspots and guides control measure placement.
The December 2026 WEL: Why This Is a Wake-Up Call for Logistics Operators
From 1 December 2026, Australia’s occupational exposure limit for DPM drops to 0.01 mg/m³ REC (8-hour time-weighted average). This represents a tenfold reduction from the previous limit of 0.1 mg/m³.
This change applies to all workplaces—not just mining and construction. Warehouses, transport depots, logistics facilities, fleet service areas, and any operation using diesel-powered equipment must comply.
What This Means Practically
Many warehouses currently operating diesel forklifts are likely exceeding the new limit without knowing it. Even modest forklift utilisation in a poorly ventilated space can generate DPM concentrations of 0.02–0.05 mg/m³. The new limit cuts this acceptable range in half.
Non-compliance carries serious penalties:
– Regulatory enforcement action from state regulators (SafeWork NSW, WorkSafe Victoria, etc.)
– Potential prosecution under health and safety legislation
– Reputational damage, especially for large 3PL operators and logistics companies
– Civil liability if workers develop occupational disease and can prove negligence
– Supply chain impacts if major clients require proof of DPM compliance
Compliance Requires Three Steps
First, measure current exposure through personal and area sampling. You cannot comply with a limit you have not measured.
Second, assess existing control measures (ventilation, equipment choices, work practices) and identify gaps.
Third, implement engineering controls (improved ventilation, DOC retrofits, fleet transition) or administrative controls (shift rotation, work zone separation) to achieve and maintain compliance.
This timeline means action is urgent. December 2026 is now nine months away.
Who Is Most Exposed? Worker Roles and Shift Patterns That Matter
DPM exposure in warehouse and transport environments is not evenly distributed across the workforce. Specific roles face significantly higher risk.
Highest-Risk Worker Categories
Forklift Operators
Highest exposure. They operate engines for entire shifts, often in poor ambient air quality from other equipment. Seated position keeps their breathing zone close to engine exhaust.
Warehouse and Dock Supervisors
Often stationary in high-activity zones, supervising multiple equipment movements. Long shifts (often 10+ hours) in elevated-DPM areas.
Materials Handlers (Manual Work in Loading Zones)
Workers loading/unloading trucks or moving goods between storage areas encounter concentrated DPM from idling trucks and active forklifts.
Cold Storage Operators
Highest-risk role in facilities with refrigerated storage. Confined environment with minimal ventilation. Continuous exposure throughout shifts.
Fleet Mechanics and Service Technicians
Service bays with running diesel engines, fuel system work, and exhaust diagnostics create extremely high exposures—often 0.05–0.15 mg/m³ in facilities with poor ventilation.
Night-Shift Operators
Statistical risk factor: night shifts often operate with lighter supervision, more equipment idling, and less incentive for forklift discipline (staggered driving patterns, minimised start-stop cycles).
Exposure Duration and Intensity
Workers completing full 8-hour or 10-hour shifts in high-exposure zones face cumulative daily dose risks. A forklift operator in a facility with 0.02 mg/m³ ambient DPM inhales approximately 0.16 mg of elemental carbon daily. Over a year, this totals 40+ mg—a significant occupational dose.
Rotating workers through lower-exposure zones during shifts, or limiting operator hours in the highest-risk areas, can substantially reduce personal exposure.
Monitoring Strategy for Warehouses: Personal vs. Area Sampling
Effective DPM monitoring compliance requires a layered monitoring approach combining personal and area sampling.
Personal Sampling: Who and When
Personal (breathing zone) sampling measures the actual inhalation exposure of individual workers. This is the legal standard for exposure assessment and compliance demonstration.
For warehouse and depot operations, personal sampling should target:
– All forklift operators (at least 3–5 operators across different shifts)
– Dock supervisors and materials handlers in high-activity zones
– Cold storage and fleet maintenance personnel
– Night-shift operators (separate sampling to assess shift-related variation)
Sampling frequency depends on operational scale:
– Small facilities (5–10 forklifts): Initial baseline sampling (3–5 workers), then repeat annually
– Large facilities (20+ forklifts): Quarterly sampling; more frequent if controls are being modified
– Cold storage and fleet service areas: Baseline and then every 6 months
Personal sampling requires workers to wear a calibrated pump (typically 2–4 L/min flow rate) on a belt or harness throughout a full shift. The sample is then analysed by a NATA-accredited laboratory using NIOSH Method 5040 to measure elemental carbon.
Area Sampling: Hotspot Identification and Ventilation Assessment
Area (static) sampling measures DPM concentration at fixed locations. While it cannot replace personal sampling for compliance, it is invaluable for:
- Identifying and confirming hotspot zones
- Assessing ventilation effectiveness before and after control improvements
- Verifying that engineering controls (e.g., DOC retrofits, improved ventilation) are working
- Baseline data collection before expensive control measures are implemented
A typical hotspot mapping exercise samples 4–8 fixed locations across the facility:
– Forklift movement corridors
– Stacking zones
– Loading dock (at truck door level and central dock area)
– Cold storage entry point
– Fleet maintenance area
– Ambient outdoor reference point
Area samples should be collected during normal operations and for sufficient duration (4–8 hours) to capture representative conditions. Early morning vs. mid-shift vs. late-shift timing can reveal patterns.
Frequency and Seasonal Considerations
Warehouse ventilation performance varies seasonally. Summer heat may drive higher natural air exchange; winter heating systems may be configured to minimise fresh air intake. Sampling across seasons (summer and winter) provides robust data.
For facilities making control changes (new ventilation system, fleet conversion, work practice changes), before-and-after area sampling proves the effectiveness of the investment.
Control Measures: From Ventilation to Forklift Fleet Transition
Once monitoring reveals non-compliance or elevated exposure, control measures must be implemented in priority order.
Engineering Controls (Highest Priority)
Ventilation Improvement
If area sampling shows DPM concentrations are 0.015–0.025 mg/m³, ventilation optimisation is the first intervention.
Options include:
– Installing or upgrading mechanical exhaust systems with adequate fresh air intake
– Adding dedicated extract at highest-emission zones (dock areas, maintenance bays)
– Ensuring supply air is filtered (MERV 13 minimum) to reduce background DPM
– For cold storage, designing air handling to permit higher exchange rates during peak operation hours
– Installing displacement ventilation in high-activity zones (low-velocity, high-volume supply air moving across the floor and out via high-level exhaust)
Ventilation upgrades typically cost $15,000–$50,000+ depending on facility size and complexity. But the compliance benefit often justifies the investment for large facilities.
Diesel Oxidation Catalysts (DOCs) on Forklifts
DOC retrofits reduce DPM emissions from diesel forklift engines by 30–50%, depending on engine condition and retrofit design. A full fleet retrofit might cost $3,000–$5,000 per vehicle but significantly improves compliance margins, especially in facilities that cannot achieve adequate ventilation.
Switching to Alternative-Fuel Equipment
For new equipment purchases or major fleet upgrades, LPG or electric forklifts eliminate DPM entirely. Electric forklifts are increasingly cost-competitive, especially in cold storage where battery performance is no longer a constraint (modern lithium systems work well at low temperatures). While upfront cost is higher, lifetime operating costs are often lower.
For existing diesel fleets, a phased transition (replace 30% of fleet with electric, maintain compliance through monitoring and ventilation) may be the most economically practical path.
Administrative and Work Practice Controls
Forklift Operation Discipline
– Minimise engine idling: require operators to shut down between movements
– Stagger operation: where feasible, limit the number of simultaneous forklifts in high-density zones
– Speed reduction: slower operation generates less turbulence and DPM suspension
Shift Rotation
– Rotate workers through lower-exposure zones
– Limit highest-exposure roles to shorter shifts where possible
– Ensure night-shift operations have supervisory oversight to enforce practices
Maintenance Scheduling
– Regular engine maintenance (fuel injector cleaning, filter replacement) keeps DPM emissions at minimum levels
– Schedule servicing during off-peak hours to avoid overlapping with high-activity periods
Training and Awareness
– Educate operators about DPM hazards and the new WEL
– Establish performance expectations for idling control and emission discipline
– Include DPM exposure risks in induction and toolbox talks
Cold Storage and Refrigerated Environments: Special Considerations
Cold storage depots and refrigerated warehouses demand heightened attention because ventilation constraints are greater than standard warehouses.
Why Cold Storage Is High-Risk
Temperature control requires a tight building envelope. Fresh air intake is minimised to reduce heating/cooling load. In many cold stores, the only air exchange comes from dock door openings during receiving/dispatch. During closed-door periods, DPM can accumulate rapidly.
Diesel-powered reach and counterbalance forklifts are the norm in cold storage because they tolerate low temperatures better than alternatives. Electric forklifts have historically been avoided due to battery performance concerns, though modern lithium systems are changing this.
Monitoring and Baseline Assessment
Cold storage facilities should prioritise both personal sampling (operators) and temperature-controlled area sampling. DPM concentration and particle size distribution can shift at low temperatures; baseline data collection is essential.
Area sampling should include:
– Interior storage zones (at multiple heights—DPM distribution varies vertically in cold stores)
– Loading dock interior and exterior
– Equipment servicing areas
Control Measures Specific to Cold Storage
Controlled-Temperature Ventilation
Work with HVAC specialists to design ventilation that maintains temperature while increasing air exchange during peak operation hours. Options include:
– Demand-controlled ventilation (CO₂ sensors trigger increased fresh air during high equipment activity)
– Destratification fans to improve air mixing without requiring higher overall exchange rates
– Heat recovery ventilation (supply fresh air, recover heat from exhaust)
Electric Forklift Adoption
Modern electric forklifts (especially lithium-equipped models) perform reliably in cold stores and eliminate DPM entirely. A phased transition (30% of fleet over 3–5 years) is economically feasible for many operators.
Shift Scheduling
Concentrate equipment-intensive operations into shorter time windows rather than spreading across the full shift. Use non-equipment periods for stock management and administrative work.
Fleet Maintenance Areas: The Highest-Risk Zone
Fleet maintenance bays and diesel mechanics’ workshops represent the most extreme DPM exposure environment in any logistics operation.
Why Maintenance Areas Are Critical
Diesel mechanics work within metres of running engines. Operations include:
– Engine start and diagnostics (baseline DPM generation)
– Fuel system work (fuel lines disconnected, injectors cleaned)
– Exhaust component removal and replacement
– Post-service test runs (engines running at load)
Even in a well-designed maintenance facility, DPM concentrations can exceed 0.05–0.10 mg/m³ during active service work. For a mechanic completing 3–4 full service jobs per day, cumulative exposure easily exceeds the new WEL.
Essential Controls for Maintenance Areas
Dedicated Ventilation Design
– Extract ventilation must be positioned to capture exhaust directly (flexible ducting or overhead extraction at engine level)
– Supply air must be fresh and filtered
– Negative pressure in the maintenance bay (relative to surrounding areas) prevents DPM spread
– Minimum air change rate: 8–12 exchanges per hour during maintenance operations
Engine Emissions Control During Servicing
– Operate test runs outdoors or in specially ventilated test cells, not inside the maintenance bay
– Use exhaust hoses connected to extract systems during diagnostic work
– Minimise idle time during service breaks
Respiratory Protection as Interim Measure
– P2 or P3 respirators may be required during specific high-exposure tasks (fuel injector cleaning, manifold removal) until engineering controls are optimised
– Respirators are not long-term solutions but can bridge the gap during control installation
Baseline and Ongoing Monitoring
– Personal sampling for all mechanics (each mechanic, full shift)
– Area sampling during normal service operations and after control implementation
– Quarterly monitoring during the first year of operation; annual thereafter if compliant
FAQ
1. What is the new DPM exposure limit in Australia, and when does it apply?
From 1 December 2026, the occupational exposure limit for diesel particulate matter is 0.01 mg/m³ respirable elemental carbon (8-hour time-weighted average). This applies to all workplaces, including warehouses, transport depots, and logistics facilities. The previous limit was 0.1 mg/m³—the new limit is ten times lower.
2. Do I need to monitor DPM if I only operate a small number of diesel forklifts?
Yes. The new WEL applies to all workplaces using diesel-powered equipment. Even a small warehouse with 3–4 forklifts in a poorly ventilated space can exceed 0.01 mg/m³. A baseline assessment is essential to determine your current exposure level. If monitoring shows compliance, ongoing surveillance sampling is still recommended (annual minimum). If non-compliant, control measures must be implemented immediately.
3. What is the difference between personal and area sampling, and which do I need?
Personal sampling measures the actual breathing zone exposure of individual workers wearing a calibrated pump throughout their shift. This is the legal standard for compliance demonstration. Area sampling measures DPM concentration at fixed locations and is useful for identifying hotspots and assessing ventilation effectiveness. A comprehensive monitoring strategy uses both: personal sampling for compliance assessment and area sampling to guide control measure placement.
4. Can I replace diesel forklifts with electric ones gradually, or must I do it all at once?
A phased transition is practical and economically sound. Converting 30% of your fleet to electric over 3–5 years, combined with ventilation improvements and operational controls, can achieve compliance while spreading capital costs. The key is ensuring that control measures (ventilation, DOCs on remaining diesel fleet, operational discipline) maintain WEL compliance throughout the transition period. Ongoing monitoring guides the pace of transition.
5. How much does DPM monitoring cost, and what should I expect to pay for a compliance assessment?
A baseline DPM assessment for a small warehouse (5–10 workers) typically costs $2,500–$4,500. This includes personal and area sampling, laboratory analysis, report preparation, and recommendations. Larger facilities ($5,000–$10,000+) may incur higher costs due to multiple worker sampling and complex ventilation assessment. Costs vary depending on facility size, number of workers, and extent of area sampling. It is essential to obtain quotes from NATA-accredited providers with occupational hygiene qualifications.
6. What should I look for in a DPM monitoring provider?
Ensure the provider is a suitably qualified occupational hygienist (AIOH or BOHS accreditation). Verify that samples are analysed by a NATA-accredited laboratory using NIOSH Method 5040. Request references from similar facilities (warehouses, depots, logistics operations). Review their reports to confirm they include sampling strategy, QA/QC data, results compared to the WEL, uncertainty analysis, and specific control recommendations. Avoid providers who offer monitoring without NATA accreditation or who lack occupational hygiene qualifications.
The Path Forward
Diesel particulate matter in warehouses and transport depots is a compliance issue with an immovable deadline. December 2026 is not a distant future—it is now the operational reality for logistics managers, facilities directors, and health and safety teams.
The good news: most warehouses and depots can achieve compliance through a combination of monitoring, ventilation optimisation, operational discipline, and strategic equipment transition. The financial investment is manageable when spread over a few years. The health benefit to workers is immediate and substantial.
The first step is always measurement. You cannot control what you do not measure, and you cannot comply with a limit you have not assessed against.
Running diesel forklifts or delivery trucks indoors? You may already be exceeding the new December 2026 limit. Book a DPM assessment with Anitech to understand your current exposure and identify the control measures that work best for your operation. Our occupational hygienists have two decades of experience helping Australian logistics operators achieve compliance cost-effectively.
Let’s ensure your warehouse is safe for your workers—and ready for the new limit.
Related Reading
Complete guide to DPM monitoring in Australian workplaces
New December 2026 DPM exposure limit: What it means for your business