This study investigates the impact of bushfire-related fine particulate matter air pollution, with a diameter of 2.5 micrometres or less (PM2.5), on mortality risk in six Australian states and one territory from 2001 to 2020. Using data from the Australian Institute of Health and Welfare (AIHW) and a bushfire-validated database, we analysed daily mortality rates and air quality measurements to estimate the number of excess deaths attributable to bushfire smoke pollution. We estimated daily PM2.5 at the 5km grid cell level for the Australian Continent from 2001 to 2020 using PM2.5 data from air pollution monitoring sites from each state and territory, combined with a range of land use and related data using a Random Forest statistical model. We extracted dates for bushfire episodes and calculated the non-bushfire PM2.5 level for each day using the seasonal and trend loess (STL) decomposition method. Therefore bushfire PM2.5 was identified as the difference in the daily PM2.5 concentrations above the expected non-bushfire levels (from STL). The daily grids of PM2.5 concentrations were then averaged over the Greater Capital City area for each city (ABS GCCSA zones). The impact of bushfire PM2.5 on daily death counts in various age groups was estimated using a recently published exposure-response function from a distributed-lag non-linear model from Sydney, Australia. Preliminary results suggest that bushfire-related PM2.5 exposure is associated with increased attributable mortalities. Furthermore, the health burden varied between different regions in Australia, with some areas experiencing a higher impact than others. These findings highlight the importance of measures to reduce bushfire smoke exposure and the need for appropriate public health strategies to mitigate the adverse health impacts of bushfires.
Keywords: Bushfire, air pollution, burden of attributable mortality, distributed-lag non-linear model, public health strategies.