Two workers injured at construction site
WARNING: May contain distressing content to some readers.
Earlier this year, two workers suffered severe burns following a flash fire at a construction site.
Early investigations indicate the two workers were waterproofing a structure using several different materials. The waterproofing materials contained chemicals that can produce flammable vapours at ambient or room temperatures. In addition, the workers were using a covered temporary structure to prevent wet weather affecting the area.
The ignition source appears to have been a heat gun, which was being used to assist in the application of the waterproofing materials, resulting in a flash fire. The flash fire was confined by the temporary enclosure which created an explosion.
Investigations are continuing.
These findings are not yet confirmed, and investigations are continuing into the exact cause.
Safety issues
Workers and others may suffer serious injury or even death because of a fire or explosion. Damage to property is also likely. Fire and/or explosions occur when three primary elements come together, known as ‘the fire triangle’.
These elements are:
- fuel (a flammable or combustible substance)
- oxygen (usually in the air)
- ignition (a source of energy sufficient to cause ignition)
Fuel in the form of flammable liquids including petrol, ethanol, enamel paints or thinners, and various solvents emit hazardous vapours which can ignite if not effectively managed. The risk of ignition is increased if works are being conducted within a confined area with limited or reduced ventilation. This is because vapours can become trapped and accumulate, forming a flammable or explosive concentration in the atmosphere.
An ignition source can be any energy source that has the potential to ignite. They are generally categorised into three broad types: flames, sparks and heat. Examples of ignition sources are:
- Flames: welding flames, gas heaters, pilot lights smoking
- Sparks: welding arcs, starters for fluorescent lighting, static electricity, friction from grinding and portable electrical equipment such as power tools
- Heat: hot surfaces such as light bulbs and ovens and heat generating tools
When undertaking work using flammable and combustible materials, it is also important to identify sources of oxygen including naturally occurring oxygen levels that are always present in air.
Ways to manage health and safety
Effective risk management starts with a commitment to health and safety from those who manage the business. If an incident occurs, you will need to show the regulator that you have used an effective risk management process. This responsibility is covered by your primary duty of care in the Work Health and Safety Act 2011.
Use the hierarchy of controls to help decide how to eliminate and reduce risks in your place of work. The hierarchy of controls ranks types of control methods from the highest level of protection and reliability to the lowest.
It is a step-by-step approach to eliminating or reducing risks. You must work through the hierarchy of controls when managing risks, with the aim of eliminating the hazard, which is the most effective control.
Possible control measures to prevent similar incidents
A person conducting a business or undertaking (PCBU) must manage the risks to health and safety associated with a hazardous atmosphere or an ignition source in a hazardous atmosphere at the workplace. The Work Health and Safety Regulation 2011 requires specific controls for prevention of fire and explosion risks associated with hazardous chemicals. These include:
- s51 - A PCBU at a workplace must manage risks to health and safety associated with a hazardous atmosphere at the workplace.
- s52 - A PCBU at a workplace must manage risks to health and safety associated with an ignition source in a hazardous atmosphere at the workplace.
A PCBU must manage risks to health and safety associated with a hazardous atmosphere. This includes identifying all sources of ignition, such as welding, hot-cutting, use of thermal tools such as heat guns and spark generating activities like grinding and cutting. These activities can generate heat, flames, and sparks that could cause an ignition of flammable and combustible substances.
A hazardous atmosphere is created when the atmosphere has a concentration of flammable vapour that exceeds five per cent of the lower flammable explosive limit (LEL) for the vapour. For example, water proofing products can contain up to 50% acetone and other hazardous chemicals that emit flammable vapours.
Using acetone as an example, this chemical has a LEL of 2.6% by volume in air. You can refer to the products Safety Data Sheet for further information. When using acetone, a hazardous atmosphere is generated at 0.13% by volume in air (i.e. 5% of 2.6%) – this is a small amount of acetone vapour mixed in air.
Safe System of Work
A safe system of work should be implemented to manage the fire and explosion risks associated with ignition sources, and hot work activities on and around containers that contain flammable or combustible liquid, and in areas where there is likely to be a hazardous atmosphere.
Use the hierarchy of controls to help decide how to eliminate and reduce risks in your place of work. The hierarchy of controls ranks types of control methods from the highest level of protection and reliability to the lowest. It is a step-by-step approach to eliminating or reducing risks. You must work through the hierarchy of controls when managing risks, with the aim of eliminating the hazard, which is the most effective control.
Effective controls for chemical fire and explosion risks are made up of a combination of controls including elimination, substitution, engineering and administration.
Elimination
Elimination is the most effective control measure and must always be considered before other control measures. For example:
- you may choose to not use a hazardous chemical (such as a water-based cleaner instead of flammable solvent based cleaner). This will eliminate the generation of flammable vapours.
- eliminating potential ignition sources from the area.
If this is not reasonably practicable, the risk must be minimised by using one or more of the following control measures. Examples can include but are not limited to:
Substitution
Alternative products to complete the task is recommended where appropriate. This can include substituting a highly flammable product with a less-flammable product, using alternative methods for drying during weather events that do not introduce ignition sources into hazardous atmospheres.
Engineering
Installing ventilation to avoid the creation of a hazardous atmosphere to avoid accumulation of vapours in an enclosed area. The aim of ventilation is to disperse flammable vapours. It can be achieved using natural or mechanical ventilation systems.
Ventilation is a significant engineering control. Correct design is essential to ensure it is effective. There are a range of different ventilation systems, and the most appropriate form needs to be used. Ventilation systems should be suitable for the types of hazardous chemicals and the nature of the work.
To ensure the effectiveness of ventilation systems, they should be designed in accordance with appropriate technical standards and installed and maintained by a competent person with regular maintenance checks as per manufacturer’s recommended guidelines.
Administration
Administration controls include developing a safe system of work to manage fire and explosion risks. Administrative controls should only be considered when other higher order control measures are not practicable, or to supplement other control measures.
This could include, but is not limited to the following examples:
- Using portable gas detectors to monitor hazardous atmosphere levels and identify where flammable gas levels are above 5% LEL.
- Ensuring containers of hazardous chemicals are used, handled and stored away from ignition sources (e.g. electrical or gas heating appliances).
- Developing policies and safe work procedures for the use, handling, storage, clean up and disposal of hazardous chemicals.
- Consulting with workers and others involved in the task to obtain feedback on processes and safe work procedures.
- Developing a maintenance schedule for engineering control measures.
- Providing workers with information, training and instruction on:
- the nature of the hazardous chemicals and the risks to workers while considering the health and safety information located within the product’s Safety Data Sheet (SDS),
- the availability of SDS for all hazardous chemicals, how to access the SDS, and the information that each part of the SDS provides,
- arrangements to deal with emergencies, including evacuation procedures, containing and cleaning up spills and first aid instructions,
- work practices and procedures to be followed in the use, handling, storage, cleaning up and disposal of hazardous chemicals.
The control measures you put in place should be reviewed regularly to make sure they operate as planned.
More Information
- Managing risks of hazardous chemicals in the workplace Code of Practice 2021 (PDF, 1.21 MB)
- Hazardous chemicals
- Controlling fire and explosion risks
- Labelling and safety data sheets
- How to manage work health and safety risks Code of Practice 2021 (PDF, 0.65 MB)
If this information has caused distress, there are services to help:
- Lifeline – 24/7 crisis support service, including phone, texting and chat services.
- Beyond Blue – information and support for anxiety, depression and suicide prevention for everyone in Australia.
- Black Dog Institute – research and resources on mental health in the workplace.
- SANE – helpline service, as well as resources on mental health.
Have you been affected by a workplace fatality, illness or serious injury?
For advice and support, visit our Facebook page or email ohs.coronialliaison@oir.qld.gov.au.