Business Toolbox

Currently, the workplace exposure standards for airborne contaminants does not include a specific exposure standard for diesel engine emissions. Although the recommended DPM standard for diesel is an eight-hour time weighted average of 15 µg respirable elemental carbon per cubic metre. 

Exposure to diesel engine emissions poses a risk to workers’ lung health and can lead to cancers. It is relevant to Australian workplaces where diesel fumes are generated including construction, mining, transport and agriculture industries.  

Workplace exposure 

Diesel exhaust may also be generated from stationary power sources such as generators and winch motors including those mounted to vehicles. These may be used in tunnels, alongside railway lines during maintenance work and on construction sites.  

Levels of exposure can be higher in enclosed, poorly ventilated areas where the concentration of exhaust can build up such as vehicle repair workshops, tunnels, partially covered roadways and walkways.  

Workers who may be exposed to diesel exhaust include drive-in booth operators, miners, construction workers, oil and gas workers, airline ground workers, forklift drivers, loading dock workers, truck drivers, farmworkers, stevedores and vehicle maintenance workers. Research has estimated 1.2 million Australian workers were exposed to diesel exhaust in the workplace in 2011, according to Safe Work Australia. 

Incidental exposure 

Incidental exposure refers to situations where the source of diesel exhaust is not under the control of the workplace. This exposure needs to be minimised. 

Workers at risk of incidental exposure may include workers who spend a significant amount of time around trucks that are unloading and loading, and diesel-powered plant and machinery. Other workers at risk include those who carry out work near busy railway lines and roadways, workers in takeaway outlets, toll booth operators, traffic controllers, carpark attendants and material handling operators. 

Tips for managing diesel exhaust risks 

1. Find out what could cause harm

• Observe the workplace and work tasks to identify where workers may be exposed to diesel and how workers interact with the plant. 
• Visually inspect the plant before operation to determine faults or damage and during operation to see if blue, black or white smoke is being emitted.
  - Blue smoke (mainly oil and unburnt fuel) is caused by partly burnt fuel from badly worn engines which are poorly serviced or tuned.
  - Black smoke (soot, oil and unburnt fuel) is produced if there is a mechanical fault with the engine or if the engine is working near its maximum speed.
  - White smoke (water droplets and unburnt fuel) is produced when the engine is started from cold, and disappears as the engine warms up.
• Ask your workers about any issues they may have with diesel exposure including during operation, inspection, maintenance, repair and transport.
• Review your incident and injury records looking for any symptoms, for example, whether they experience irritation of the eyes, nose, throat and lungs, light-headedness or nausea. 

2. Assess the risks if necessary

Once you have identified the hazards at your workplace, you may need to assess the risks – the likelihood of somebody being harmed by the hazard and how serious the harm could be. The level of risk depends on the duration and frequency of exposure. Think about how incidents could happen and who might be harmed. 

A risk assessment can help you work out what action should be taken to control the risk and how urgently the action needs to be taken. An occupational hygienist or other competent person can assist in making this assessment. 

The following questions may help you work out whether diesel exhaust emissions may pose a risk to workers: 

• Is there visible smoke near the exhaust point? What is the type of smoke, for example is it white, black or blue? How could it be avoided? 
• Is there a visible haze in the workplace? Can it be avoided and how? 
• Are vehicles and plant left idling when indoors or in enclosed spaces? 
• How many engines are running at any one time? Are they all necessary? 
• Are there soot deposits in the workplace; how significant are they? What can be done to avoid them? What methods are in place for regularly cleaning the workplace?
• Have there been any ill-health complaints from potentially exposed groups? If yes, what has been done about it?
• Is the engine being operated at full speed or left idling? Can this be avoided? 
• What is the state of the engine, and how many kilometres or hours have been completed? Can the engine efficiency be improved, and can operating times and distances be reduced? Improving the efficiency of the engine will also bring financial benefits. 
• What happens to the exhaust emissions: do they enter directly into the workplace, or are they piped away so they don’t enter the workplace where they are being produced or any other premises? Are they processed through a treatment system? Could they trigger your fire detection system?
• Is it necessary to use diesel engines, or can alternative power sources be used? 

3. Take action to control the risk

The ways of controlling risks are ranked from the highest level of protection and reliability to the lowest. This ranking is known as the hierarchy of controls. You must work through this hierarchy to work out which controls to implement. 

Elimination and substitution – consider if risks from using the diesel exhaust can be eliminated, for example by replacing diesel-powered plant with electric, propane, compressed natural gas or petrol-powered plant. It is important to consider and manage any risks introduced by the use of alternative power sources. If this is not reasonably practicable, consider the following options in the order they appear below to minimise risks, so far as is reasonably practicable: 

Isolating the hazard – by separating the workers from the diesel exhaust. For example:
- enclosing the worker in a sealed, air-conditioned cabin
- providing positive pressure ventilation, and
- modifying the layout of the workplace by separating the area of the workshop in which diesel engines are operating from the rest of the workshop.
Engineering controls, for example:
- using diesel exhaust gas after-treatment systems like catalytic converters to oxidise organic substances and gases, and catalysed and non-catalysed particulate traps to remove particulate matter, and
- using ventilation systems.
Administrative controls, for example:
- using processes or systems of work which will help you to reduce the generation of diesel exhaust, for example:
* switching off engines whenever possible, rather than leaving them idling, and
* adopting a program of regular engine maintenance.
- where reasonably practicable, reducing the number of workers directly exposed and their period of exposure, for example:
* ensuring office staff working adjacent to diesel exhaust emission areas are not exposed
* job rotation, and
* scheduling work to minimise the number of workers near the plant while it is operating
Using respiratory protective equipment
As exposure to diesel exhaust is best controlled at the source or by other means, respiratory protective equipment (RPE) should only be used as a last resort. In many cases it will not be appropriate to provide respirators to workers who are exposed to diesel exhaust, for example in situations such as drive-through takeaway food outlets.
Specific types of respirators must be used to prevent diesel exhaust exposure. P2 disposable respirators may be suitable if the concentration of vapour in the diesel exhaust is low. Half or full-face respirators with a filter cartridge that protect against gases, organic vapours and particles are generally more suitable. Air purifying respirators do not protect against all hazardous gases. 

4. Information, training, instruction and supervision

   must be given to workers on the health hazards associated with exposure to diesel exhaust emissions and on the proper use of control measures.

WA mining industry 

In 2020, the WA Government introduced a new workplace exposure standard for DPM for all WA mines. Mine operators must now ensure DPM does not exceed 0.1 milligrams per cubic metre of air in the workplace. 

Stakeholder feedback 

Safe Work Australia is reviewing stakeholder feedback in its consideration of whether to recommend that a workplace exposure standard for DPM is introduced in the model WHS regulations.