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Unprecedented health costs of smoke-related PM2.5 from the 2019–20 Australian megafires


In flammable landscapes around the globe, longer fire seasons with larger, more severely burnt areas are causing social and economic impacts that are unsustainable. The Australian 2019–20 fire season is emblematic of this trend, burning over 8 million ha of predominately Eucalyptus forests over a six-month period. We calculated the wildfire-smoke-related health burden and costs in Australia for the most recent 20 fire seasons and found that the 2019–20 season was a major anomaly in the recent record, with smoke-related health costs of AU$1.95 billion. These were driven largely by an estimated 429 smoke-related premature deaths in addition to 3,230 hospital admissions for cardiovascular and respiratory disorders and 1,523 emergency attendances for asthma. The total cost was well above the next highest estimate of AU$566 million in 2002–03 and more than nine times the median annual wildfire associated costs for the previous 19 years of AU$211 million. There are substantial economic costs attributable to wildfire smoke and the potential for dramatic increases in this burden as the frequency and intensity of wildfires increase with a hotter climate.

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Fig. 1: Geographic context of the analysis of health costs associated with smoke from the Australian 2019–20 fires.
Fig. 2: Smoke-related health costs for Australian fire seasons (1 October to 31 March) between 2000 and 2020.
Fig. 3: Annual smoke-related health costs.

Data availability

The data that support the findings of this study are available on request from the corresponding author on a case-by-case basis. Source data are provided with this paper.

Code availability

The custom code generated during the current study is available from the corresponding author on a case-by-case basis.


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We thank the Environment Protection Authority of Victoria, Tasmania and South Australia; the Department of Environment in Queensland; the Department of Infrastructure Planning and Environment of New South Wales; and the Department of Water and Environmental Regulation of Western Australia for providing the available hourly and daily air quality data since 2000. We thank the New South Wales government’s Department of Planning, Industry & Environment for providing funds to support this research via the Bushfire Risk Management Research Hub. N.B.-A. is supported by a Tasmania Graduate Research Scholarship, by Asthma Australia through a Top-up Scholarship and by the New South Wales Bushfire Risk Management Research Hub through a Top-up Scholarship.

Author information

Authors and Affiliations



F.H.J. and D.M.J.S.B. conceived the paper. F.H.J. drafted the manuscript. N.B.-A. conducted the analyses and contributed to the design, methods and paper. G.G.M., B.J. and A.J.P. contributed to the methodological approach and the paper. G.J.W. and D.M.J.S.B. contributed to the methods, the fire data and writing the paper.

Corresponding author

Correspondence to Fay H. Johnston.

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Extended data

Extended Data Fig. 1 Population-weighted daily PM2.5 statistic (μg/m3) by State for the 2019/2020 fire season and the median of the previous 19 fire seasons.

Vertical lines mark the 25th, 50th, 75th and 95th centiles. The interquartile range is shaded. Exposure data available from: 2012 for ACT, 2010 for TAS, 2001 for SA, 2000 for all other states.

Source data

Extended Data Fig. 2 Median population-weighted PM2.5 (μg/m3) by State and fire season.

Exposure data available from: 2012 for ACT, 2010 for TAS, 2001 for SA, 2000 for all other states.

Source data

Extended Data Fig. 3 Magnitude and costs of premature mortality estimated using risk coefficients for short term exposure, long term exposure, and by calculating the years of life lost.

Exposure data and associated costs available from: 2012 for ACT, 2010 for TAS, 2001 for SA, 2000 for all other states.

Extended Data Fig. 4 Sensitivity analysis showing the influence of constraining the maximum daily PM2.5 concentrations on the estimated health burden.

Results shown for the 2019–20 fire season and the median of the previous 19 fire seasons.

Extended Data Fig. 5 Total costs ($AUD million) across different fire identification criteria.

Sensitivity analysis showing the influence of selecting different cut-points for identifying a wildfire smoke affected day on the total estimated health related costs by fire season. (Costs in AUD Mil).

Extended Data Fig. 6 Estimated health costs ($AUD million) for each fire season by State and Territory of Australia.

Results for main analysis. Exposure data and associated costs available from: 2012 for ACT, 2010 for TAS, 2001 for SA, 2000 for all other states.

Supplementary information

Supplementary Information

Supplementary Tables 1–13 and Methods.

Source data

Source Data Fig. 2

Cumulative health costs (main analysis) for each fire season and day of fire season (1 October is Day 1).

Source Data Fig. 3

Estimated health costs ($AUD million) by state and fire season.

Source Data Extended Data Fig. 1

Daily population-weighted PM2.5 by state, date and fire season.

Source Data Extended Data Fig. 2

Population-weighted PM2.5 average by fire season for each state and all states included in study.

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Johnston, F.H., Borchers-Arriagada, N., Morgan, G.G. et al. Unprecedented health costs of smoke-related PM2.5 from the 2019–20 Australian megafires. Nat Sustain 4, 42–47 (2021).

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