Australia is the most fire-prone country in the world and the risk of severe bushfires is increasing (Figure 10) (BOM 2022).
Weather-related factors (including high temperatures, low humidity, lack of recent rain, and strong winds) can contribute to increased risk of bushfire danger. Bushfires also require an ignition source, which can be either natural (such as a lightning strike) or human (such as discarded cigarettes, electrical faults, or deliberate ignition). Hence, bushfires frequently occur in conjunction with extreme weather events such as heatwaves, droughts, or storm activity such as lightning strikes and high winds.
Figure 10: The frequency of dangerous fire weather days has increased across Australia in the last century
Source: BOM, State of the Climate 2022
Bushfire-related injury hospitalisations and deaths peaked in 2019–20, an El Niño year (Figure 11, Figure 2). There was a 15-fold increase in bushfire-related deaths in 2019–20 as compared to 2018-19 (Figure 2).
The two most common injuries that result from bushfires are smoke inhalation and burns.
Bushfire smoke inhalation leads to both acute and longer term health impacts (Rodney et al. 2021). Injury reporting counts acute hospitalisations and deaths, underestimating the overall health impacts of bushfires (AIHW 2020).
The smoke from bushfires comprises mainly water and gases, which condense on particles in the smoke. It forms clouds that subsequently contribute to various bushfire weather conditions such as strong winds, lightning and poor visibility (Da Silva 2020). These each contribute to the adversity of the environment, increasing the risk of injury from activities such as transport.
Carbon monoxide is found in smoke, formed from incomplete combustion. High concentrations of carbon monoxide bind to haemoglobin in the blood which can lead to asphyxiation and death (Da Silva 2020).
Burns in bushfires can result from radiant heat or ember attacks. More serious second- or third-degree burns are a risk with increasing fire intensity (DEA 2017).
The AIHW compared hospitalisations for respiratory conditions and burns during the December 2019 to January 2020 bushfire period with data from previous years. The largest increase in the hospitalisation rate for respiratory conditions was 11% in the week beginning 5 January 2020, with 1,100 more hospitalisations than the previous 5-year average. Increases in burns also coincided with the 2019–20 bushfire activity. The greatest increase in burns totalled 30% above the previous 5-year average in the week beginning 15 December 2019, with 55 more hospitalisations (AIHW 2021).