Contamination from fires at chemical storage sites can include a diverse range of substances, such as per- and polyfluoroalkyl substances (PFAS), heavy metals and more. These chemicals can have serious long-term impacts on health and the environment.

After the Footscray-Tottenham chemical factory fire in Melbourne in August 2018, levels of PFAS chemicals (PFOS and PFOA) were found to be 16 times higher than the safe recreational water quality levels downstream from the fire site for two weeks following the incident. EPA Victoria reported that contaminants like hydrocarbons, solvents (such as acetone), herbicides, and heavy metals were also detected.

Firefighting foams are also a common source of PFAS. Despite efforts to regulate their use, these foams have not yet been phased out. Over the years, there have been numerous high-profile cases of PFAS contamination, particularly near military bases, airports, and firefighting training sites. Recently, there has been a push for stricter regulations, more research into alternative firefighting foams, and cleanup efforts at contaminated sites.

PFAS are often called "forever chemicals" because they persist in the environment and the human body for a long time, over 35 years. They have been linked to health issues such as various cancers and thyroid diseases. Once in the environment, PFAS do not break down and can accumulate in the food chain.

Traditional water treatment plants struggle to remove some of these smaller PFAS effectively. This is why our research team at Monash University is developing a new type of membrane designed to specifically filter out these persistent environmental contaminants from drinking water.

From video footage of the fire and its aftermath, emergency services have done an excellent job in containing this dirty, and dangerous incident. 

The report at Derrimut of a sharp explosion early on in the incident indicates an initiation process, such as a spark or overheating, that might have involved storage or transfer of volatile and often oxygen-rich, carbon-based solvents, such as acetone.

However subsequent, prolonged orange-coloured flames and the evolution of thick black smoke suggest that the main fire was supported by less volatile combusting material, such as heavy oils and solvents, such as toluene. These burn less efficiently and so give off black particulate matter (smoke).

Fortunately, these less volatile materials are less likely to explode violently in a fire, but their combustion can be hard to suppress and they can generate toxic particulates and other materials in smoke and water run-off with significant health hazards if not contained. 

The nature of these contaminants would depend on the specific substances involved in the fire and its suppression.

Fire smoke from factory fires often contains many chemicals and noxious fumes which can be highly irritating to the eyes, nose and airways of people who are exposed even for periods under one hour.

Immediate symptoms such as cough are often accompanied by intense nose and eye watering, which can continue for many hours afterwards. People with underlying lung disease, especially people with asthma, who have twitchy airways, can experience these immediate irritative symptoms followed by wheezing and shortness of breath typical of an asthma attack, or over the next few days, worse asthma control. They should remove themselves from exposure as quickly as possible.

If their houses are in smoke haze area, closing all windows and doors and avoiding exercise outdoors can minimise their exposure. Taking their preventer regular medications and carrying a reliver puffer is the best protection against worsening asthma.

Fire fighters need to be aware of the same risks even though they are well protected by masks and filters than reduce these risks although they have more intense exposure. Anyone who has intense breathing difficulty or symptoms which do not settle with removal and appropriate medication, should seek medical help urgently.

It is not surprising that chemical runoff from the recent fire in Melbourne’s west might have entered local waterways. Given the scale of the event, it seems likely that any rain together with the water the fire teams used to fight the fire would have run off the building and into the local waterways carrying chemicals from the fire and the factory with it. This is similar to what happened after the West Footscray warehouse fire in 2018.
 
Although there were some scary photos of burning barrels in the Derrimut fire, we don’t know what was stored on the site or how. Without more information, further speculation is probably not helpful to residents or those working to deal with the incident.
 
It is possible there could be some effects could be seen on local creeks but these are likely to be short-term as the water works its way through the system. To be on the safe side, it would be a good idea for people and animals to stay away from waterways in the area for the time being.
 
This is not likely to be a threat to drinking water supplies in Melbourne. This is because our drinking water is sourced from areas away from the fire, and the water itself is well-treated before being provided to households.