Environmental health risks during and after a bushfire

Bushfires have the potential to cause a number of environmental health concerns beyond the immediate damage caused by the fire.

Environmental Health Officers should take a proactive role in increasing public awareness about the range of public and environmental health hazards that may occurr in and around a property and the general community following a substantial bushfire.

The following environmental health hazards need to be considered.

Environmental Health Officers should also read the Disaster and Emergency Management for Environmental Heath Practitioners (external site) produced by Office of Health Protection of the Australian Government Department of Health.

Air quality and bushfire smoke

Bush fire smokeRole of Environmental Health Officers / authorised officers

Environmental Health Officers can help to educate the local community about precautions to take to reduce the health effects of bushfire smoke or smoke haze.

Health alerts

  • Health alerts will be broadcast when smoke concentrations are a health risk. They will include information on who is likely to be affected and advice on what to do
  • The Department of Biodiversity, Conservation and Attractions issues a smoke alert when smoke from prescribed burning or bushfires may affect people in towns and communities or restrict visibility for motorists. Visit the Department of Biodiversity, Conservation and Attractions (external site) for the latest bushfire and smoke alerts.

Community health messages

It is important for some people – particularly the elderly, the very young and people with respiratory and heart conditions – to take extra precautions to avoid exposure to bushfire smoke and smoke haze.

Key messages include

  • Stay indoors and shut the doors – particularly people with heart and circulation conditions, asthma and other respiratory conditions
  • Reduce outdoor activity - limit or forego outdoor exercise to reduce breathing in air pollutants
  • Use air conditioners and filters – air conditioners that circulate indoor air. Switch off evaporative air conditioners and air conditioners that do not allow the fresh air intake to be turned off
  • Use a room air cleaner – a high powered portable air cleaner (with a high-efficiency particular air (HEPA) filter) may improve the air quality in a bedroom, which may be helpful to an individual with asthma. Room air cleaners will provide the most protection when placed in an enclosed room where people spend most of their time.
  • Use respiratory protection – if you must venture outdoors wear a P1 or P2/N95 face mask that has a tight seal around the mouth and nose and can filter airborne contaminants
  • Keep hydrated - drink plenty of water
  • Look out for the elderly
  • Anyone with an urgent smoke-related health condition should seek medical attention by dialling 000. People with other medical conditions or who are feeling unwell due to the smoke impact are advised to contact their GP or healthdirect on 1800 022 222.

Once the bushfire is contained the smoke risk should decrease and no longer present a risk to the community.

More information

Key contact

Email doh.chemicalhazards@health.wa.gov.au for questions related to air quality

Fire damaged asbestos

Fire damaged asbestosRole of Environmental Health Officers / authorised officers

Immediate response to asbestos fires by local government

Identifying possible fire damaged asbestos and its potential spread is the first priority, followed by controlling access and disturbance of it.

Any buildings or structures erected before 1990, especially in the 1970s and 1980s, should be suspected of containing asbestos, typically as flat or corrugated cement sheeting.

Possible asbestos material should be assumed to contain asbestos and to be managed accordingly, pending the results of laboratory analysis. As a priority, briefing and providing guidance and reassurance to the concerned or affected public is important.

Accessing asbestos contaminated properties

Restrict access to asbestos contaminated properties only to officers with sufficient site risk information and appropriate personal protective equipment and clothing (PPEC). Refer to Attachment 2, page 20 of the Guidance Note on the Management of Fire Damaged Asbestos 2014 (PDF 1MB) for more information.

Other critical actions, described in more detail in these guidelines include

  • assume (based on structure age) or confirm the presence of asbestos material by submitting representative suspect samples for analysis to a National Association of Testing Authorities (NATA) accredited laboratory
  • determine, to the extent practical, the impacted area, including material spread by shattering or wind effects and any possibly contaminated runoff, being conservative if in doubt
  • keeping damp or stabilising the surfaces of the areas of contamination (use PVA solution, preferably with a dye colour to identify sprayed areas), especially the footprint and immediately adjacent areas
  • if necessary and safe to do so, owners properly equipped with PPEC, and supervised, may visit the site to reclaim personal effects
  • in some cases an emergency clean-up of certain affected areas may be necessary such as main roads and access areas.

Experience and research indicate that fires are unlikely to result in airborne asbestos respirable fibre readings above the 0.01 f/ml limit using the membrane filter method, the normal detection limit. However, any asbestos-contaminated material must be left undisturbed and managed in accordance with the Guidance note on the management of fire damaged asbestos.

Asbestos professionals

Asbestos consultants – in the case of artificial surface and/or limited soil contamination this professional should be an occupational hygienist (external site).

In the case of extensive soil contamination, e.g. a large bushfire, this should be an environmental consultant (external site).

More information

Fact sheets and guidelines

Key contact

The Department of Health has extensive experience with asbestos fire contamination and is available to assist. Email doh.chemicalhazards@health.wa.gov.au for any questions regarding asbestos.

Chemicals and other hazards

Fire damaged propertyHouses, sheds and other buildings or structures that are burnt in a bushfire can leave potential health hazards in the remaining rubble and ash. Before anyone goes back to a property to clean up or retrieve personal items, be aware of the potential risks.

Hazardous material that may be present after a fire includes:

  • asbestos
  • ash from burnt treated timbers, such as copper chrome arsenate (CCA) timber
  • electrical hazards
  • medicines
  • garden or farm chemicals and pesticides
  • other general chemicals, such as cleaning products or pool chlorine
  • metals and other residues from burnt household appliances
  • ash and dust.

More information

Key contact

Email doh.chemicalhazards@health.wa.gov.au for questions related to chemical and other hazards.

On-site wastewater system damage

Fire damaged asbestosRole of Environmental Health Officers / authorised officers

Environmental Health Officers can help to educate people about managing onsite wastewater issues on their properties.

Health risk

Onsite wastewater systems, such as septic tanks (primary treatment systems), secondary treatment systems (STS), aerated wastewater treatment systems (AWTS), and their land application systems, for example plastic leach drains, sprinklers and below ground drippers and connection pipes, can be easily damaged during a bushfire.

Avoid driving or walking near a fire-affected system until it is assessed by a licensed plumber or service technician familiar with on-site wastewater systems. 

Contact with effluent or untreated wastewater from damaged on-site wastewater systems can cause illness and should be avoided at all times.

Wastewater systems  

Plastic and fibreglass on-site wastewater systems, or systems made with plastic components, are more susceptible to damage than concrete tanks particularly if installed above ground. This includes shallow PVC pipes, plastic tanks and sumps, and plastic irrigation pipework which may be installed above or below ground. Pumps and other equipment with electrical components may also be damaged.

It is recommended that damaged on-site wastewater systems are not used until repaired or replaced.


Due to the risks associated with using systems after a bushfire, the following actions are recommended:
  • if the on-site systems are damaged, make arrangements to repair the system as soon as possible to prevent sewage from backing up into the house
  • avoid driving or walking near underground pipes, tanks and tank covers and their land application systems, which may have been weakened or damaged
  • reduce water use as much as possible until the system is inspected and repaired
  • if the power has not been restored, the septic tank can be used as a temporary holding tank and pumped out periodically, provided the tank is not damaged. You may need to disconnect the pump (if present) and block the outlet to the land application area. If the tank is significantly damaged and can’t be used as a temporary holding tank, do not use the system until it is repaired or replaced.
  • once power is restored, ponding may occur near the wastewater system and these areas should be avoided. Contact a licenced plumber or authorised service technician to reassess the system
  • replace shallow PVC pipes if they have melted as they may cause blockages
  • repair or replace damaged electrical components and pumps as soon as possible.

Safety issues that need to be checked:

  • open covers/pits
  • ruptured/leaking systems (including pipes)
  • damaged/exposed pipes that may need capping/sealing off.

Failed systems are not easy to identify. However, some simple indicators may include:

  • a pungent odour around the tank and land application area
  • blocked fixtures, with wastewater overflowing from the relief point
  • high sludge levels within the primary tank
  • sewage flowing up through the toilet and sinks.

Some onsite wastewater treatment systems may rely on mechanical and electrical equipment, such as pumps, aerators and filters. This equipment may be damaged by loss of power.

Residents should not use any toilets, laundry, kitchen, bathroom or clean-up equipment connected to the onsite wastewater disposal system until:

  • all parts of the wastewater treatment and disposal system have been professionally inspected and repaired
  • onsite wastewater disposal system has been approved for use by the local authority environmental health officer.

Only trained specialists are suitably equipped to clean or repair onsite wastewater systems. This is because onsite wastewater systems may contain dangerous gases and other harmful materials.

Key contact

Email dwalert@health.wa.gov.au for questions related to wastewater.
Rainwater tank contamination

Rainwater tank contamination following a bushfireRole of Environmental Health Officers / authorised officers

Environmental Health Officers can help to educate the community about managing water quality issues in their home and surrounding community following a bushfire to ensure that tank water remains safe and fit for its usual purpose.

Heath risk

Water in rainwater tanks can be contaminated during or after a bushfire, either indirectly by ash, smoke, debris or directly by fire and firefighting activities. If there is any risk of contamination residents should be advised not to use the water from the rainwater tank for drinking water purposes until it can be confirmed to be safe.

Further information

Key contact

Email dwalert@health.wa.gov.au for questions related to rainwater tanks and water quality. 
Contaminated swimming pools

Fire damaged swimming poolRole of Environmental Health Officers / authorised officers

Environmental Health Officers can help to educate the community about appropriate remediation for contaminated swimming pools.

Health risks

After a bushfire, a swimming pool may contain debris including ash. This may affect the chemical balance of the water.

Swimming pools should either be emptied or kept chlorinated to prevent the water quality from deteriorating.

Contaminated swimming pools can be:

  • a source of odours and bacteria
  • a breeding place for mosquitoes
  • a risk to people who use them.

If the pool can be emptied

The owner / operator will need to make an assessment as to whether it is safe to empty the pool.

Advice from a building consultant may be required.

Emptying a pool situated in an area with a high water table or in water–logged soils may put the pool walls under stress.

This could result in cracking or collapsing of the pool walls, or forcing the pool up out of the ground.

It will also be important that potentially contaminated pool water can be disposed of to a location where it will not:

  • cause overflows in an already overloaded drainage system
  • contaminate other water bodies.

If it is safe to empty the pool, then all water and residue should be removed.

Flush the plumbing pipes leading to the filters and replace filters or filter media.

Once emptied, the pool floor can be cleaned and sanitised using a 10 parts per million (ppm) chlorine solution.

Walls can be cleaned with a 10 per cent bicarbonate solution. Bicarbonate is also used to raise the pH.

Once completely cleaned, the pool can be refilled using scheme water, providing this has not also been compromised by the flood.

Disinfectant can be added to bring it up to the operating parameters.

Read more about the parameters in the Code of Practice for the Design, Operation, Management and Maintenance of Aquatic Facilities (PDF 95KB).

Where a pool cannot be emptied

Where the pool cannot be emptied, a trained technical operator will need to inspect the pool. The operator will determine an appropriate treatment to remove solids from the water, for example flocculation.

Depending on the amount and type of inundation, the water may need to be treated over several days. This will allow for all undissolved solids to descend to the floor of the pool ready for vacuuming.

Only when all the sand and sludge has been removed from the pool can effective chlorination commence. The pool and filters should be superchlorinated to 20mg/l (ppm) for up to 13 hours.

Depending on the nature and amount of contamination and the volume of the pool, the chemical treatment process and chlorination of the pool may take up to 1 week to complete.

Once the pool water is visibly clean, the pool motor and filter(s) may then be used to operate at the required chemical levels (for example chlorine, pH, bromine, cyanuric acid level).

Operators should determine the time required for a complete filtration cycle.

It should be noted that 4 complete cycles of the pool water are required to achieve 98 per cent filtration of pool water.

Further information

Key contact

Email swimmingpools@health.wa.gov.au for swimming pool related queries.

Unsafe food disposal

Decomposing foodRole of Environmental Health Officers / authorised officers

  • Environmental Health Officers can help to educate the community and local food businesses about safely disposing of unsafe food.

Health risk

When bushfires cause the power to go out, it generally means the food in a fridge or freezer will go off.

Community food safety messages include:

  • If in doubt, throw it out:
    • food will remain safe in your refrigerator for 2 hours. If it has been more than 4 hours, throw the food out
    • food can remain frozen between to 24 to 48 hours in a freezer. If food has thawed out throw it out
    • food can remain frozen in a freezer that has been without power for between 1 and 2 days, provided it is in good condition and was operating at minus 15C or below. If the freezer door is kept shut, a full freezer can keep food frozen for up to 48 hours, while a half full freezer can kept food frozen for 24 hours.
  • When disposing of food, wrap it in newspaper and place in the rubbish bin. A small volume of food may be safely buried.

More information

Key contacts

Email foodsafety@health.wa.gov.au for food safety queries. 

Dead animal control

Role of Environmental Health Officer / authorised officer

  • Property owners should be advised to liaise with the local government EHO prior to undertaking disposal or burial of any significant biomass, to ensure this is being done in a consistent and appropriate manner – and avoiding ongoing risks to water table, and surrounding environment. If this is a significant (widespread) problem, it is recommended that councils or recovery teams offer and coordinate assistance or services to facilitate an orderly disposal.

Following a natural disaster, many animals, particularly farm animals may not survive.

It is important to promptly dispose of these animal carcasses to prevent fly breeding, reduce odours, and protect surviving animals from disease

Landholders should search their property for dead animals as soon as possible after a disaster, provided it is safe to do so.  In some cases, carcasses may have commercial value, so consider sending them to a rendering plant if possible.

If rendering is impractical, dispose of the dead animals on the premises. Where disposal or burial of any significant biomass, this must be undertaken in a consistent and appropriate manner in coordination with the local government.

Procedures to dispose of dead animals

  • Cover a carcass with crude oil or kerosene to keep away dogs, scavenging birds and vermin
  • Well-fed pigs are the only animal carcasses that will burn satisfactorily. Old railway sleepers can be used as fuel. Burning of other carcasses is not recommended
  • Bury other carcasses. Use earth moving equipment if it is available
  • Choose a site where subsurface drainage will not reach water supplies
  • Bury the carcass at least 90cm to 120cm deep, so predatory animals won't be able to reach them
  • If quicklime (Builder’s Lime) is available, cover the carcasses with it before backfilling. Quicklime speeds up the decomposition process
  • Work with the local government animal control officer for further guidelines.

Key agencies

The Environmental Health Directorate will endeavour to support local government Environmental Health Officers whose communities are impacted by severe bushfires, with staff available to assist with any queries related to environmental health matters. A formal request for on-site environmental health support will also be considered. 

Last reviewed: 11-02-2021
Produced by

Environmental Health Directorate