summer wildfires taint
by Dr Michael J. Leach
our air…hospital visits
and deaths exceed norms
In contemporary Australia, the frequency and intensity of bushfire events have increased alongside the rate of global warming. This disastrous consequence of climate change is illustrated by the 2019-20 Australian bushfire season: the so-called ‘Black Summer’. Over the course of that bushfire season, hundreds of wildfires burned across 24 million hectares of land inhabited by diverse flora, fauna, and humans, primarily in the southeast of Australia. Bushfire events peaked during December 2019 and January 2020.
Bushfire smoke has multiple real-world impacts, including adverse effects on public health. In order to gain a preliminary understanding of the public health burden of bushfire smoke generated by the 2019-20 Australian bushfire season, Arriagada et al. (2020) undertook a quantitative analysis of publicly available air quality, demographic, and health data over the period 1/10/2019-10/2/2020. Population-level exposure to particulate matter below a known critical level of 2.5 micrometres in diameter (i.e. PM2.5) was estimated for the four most bushfire-affected jurisdictions of Australia: New South Wales (NSW), the Australian Capital Territory (ACT), Queensland, and Victoria. PM2.5 concentrations were compared with past average values recorded by air quality stations. The authors also determined, for each jurisdiction, the incidence of several relevant health outcomes: hospital admission for respiratory or cardiovascular issues, asthma-related visits to emergency departments (EDs), and excess deaths. The PM2.5 data and incidence rates were used to calculate a measure of exposure-response risk.
The authors’ analysis revealed that, across the four Australian jurisdictions under investigation, bushfire smoke led to an estimated 2,027 hospital admissions for respiratory issues, 1,305 asthma-related visits to EDs, 1,124 hospital admissions for cardiovascular issues, and 417 excess deaths. For each of these health outcomes, the public health burden was greatest for NSW followed by Victoria, Queensland, and then the ACT. It is important to note, however, that there are levels of uncertainty attached to these estimates: they may be underestimates or overestimates of the true values. The authors highlighted the importance of more detailed epidemiological analyses of the public health burden associated with bushfire smoke in Australia. While such studies would build the evidence base in this area, the preliminary statistics reported here are still substantial in magnitude and suggestive of the need for bushfire prevention and preparedness strategies in contemporary Australia.
The original research article described here is available open access online:
Arriagada NB, Palmer AJ, Bowman DMJS, Morgan GG, Jalaludin BB, Johnston FH. (2020). Unprecedented smoke-related health burden associated with the 2019-20 bushfires in eastern Australia. Medical Journal of Australia. 213(6): 282-283. https://www.mja.com.au/journal/2020/213/6/unprecedented-smoke-related-health-burden-associated-2019-20-bushfires-eastern
Michael J. Leach (@m_jleach) is an Australian epidemiologist, biostatistician, and poet who works at Monash University. His poetry collections include Chronicity (MPU, 2020) and Natural Philosophies (Recent Work Press, forthcoming).
Check out more sciku by Michael, including ‘The Core Correlate of COVID-19 Vaccine Acceptance‘, ‘Drug-Induced Hip Fractures‘, ‘The Psychopharmacological Revolution‘, ‘Quality of Life at Seven Years Post-Stroke‘, ‘The Early Impacts of COVID-19 on Australian General Practice‘, and ‘Australian Science Poetry‘ with science communicator Rachel Rayner. Michael also has another Covid-19-related sciku published in Pulse which is well worth checking out: ‘flu shot announcement‘.