Corona and climate: bushfire smoke exposure, COVID-19 and respiratory health

By Liberty Lawson, Content Editor, Sydney Environment Institute

Liberty Lawson: You recently co-authored a paper published by the Medical Journal of Australia looking at the impact of bushfire smoke exposure on health. Could you walk us through your findings and their significance?

Geoff Morgan: This study looked at the health burden due to the recent bushfires that covered much of south-eastern Australia from October 2019 to February 2020. It used a methodology which looked at the attributable health burden due to environmental exposure, in this case, air pollution from the bushfires. We estimated the proportion of air pollution that was related to the bushfire smoke during that period in Queensland, New South Wales, the ACT and Victoria, and combined this data with information on the health risks due to air pollution from local and international epidemiological studies.

We estimated 417 excess deaths due to the fire smoke pollution, 1124 excess cardiovascular hospital admissions, 2027 excess respiratory hospital admissions and 1305 emergency department admissions. We know that air pollution, including fire smoke, is associated with a whole range of adverse effects on respiratory and cardiovascular health and our study is a way of trying to understand the magnitude of that effect on the population of South Easter Australia exposed to fire smoke during the catastrophic 2019/20 fire season.

It’s quite a contrast to see your figure of 417 in comparison with the 33 deaths that occurred directly from the fires.

This is a tragic situation for all the families who lost loved ones from the direct effects of fire including firefighters and people defending the home or fleeing from the fire front.  It’s difficult to compare the deaths from the direct effect of the fire and the premature deaths that occur due to smoke pollution because we know that smoke pollution generally affects vulnerable people with existing chronic respiratory or cardiovascular disease, as well as the elderly and young children. For example, one of the uncertainties around the mortality burden due to air pollution is the duration of life lost from exposure to air pollution, while acknowledging that any loss of life is a terrible thing. We assume that the people being affected by air pollution and whose deaths have been brought forward are not young, fit health people. So it’s difficult to compare the loss of life due to direct effect of the fire front and the indirect effects of fire smoke.

Our study illustrates that fire smoke pollution has real health consequences and that we need to better manage fire in our environment as well as the messaging around fire smoke pollution so that we help people to reduce their exposure and thus reduce their risk of adverse health effect.

Do you see any trends in the statistics that are coming out around COVID-19, with the virus, like the smoke, disproportionately affecting populations that are already quite vulnerable?

There is some work emerging that the impacts of COVID-19 may be higher in locations with higher air pollution. We know that the people who are most vulnerable to COVID-19, elderly people with pre-existing disease, are also vulnerable to the effects of air pollution. And air pollution exposure, over a long period of time, can cause increased prevalence of those conditions.  There may be higher rates of vulnerable people in those areas with high air pollution and so these vulnerable groups would also be vulnerable to the effects of the coronavirus.

The methodology for this study used epidemiological modelling, do you think it would benefit future research if there was more data collected in real-time by health authorities?

Epidemiologists are always going to say there should be more data collected. One of the complexities around air pollution research is that no one is classified as having died from air pollution, as happens with chronic disease or cancer, no one gets air pollution on their death certificate. And so, it’s only by epidemiological research and statistical modelling that we can examine the many ways in which air pollution affects our health.

What would be useful is to find out more about people’s exposure to air pollution – for example, how much air pollution exposure people experience where they live, where they work, as well as inside the home and the workplace. That could help us get a better assessment of their levels of exposure during their lifetime, or even just prior to an adverse health event. We have done studies where we have looked at ambulance call-outs and air pollution levels and found that the level of air pollution where the ambulance picked up the patient – not necessarily their home – is associated with ambulance call-outs and specific health conditions.

So there is a significant causal link, but since this isn’t directly reflected in patient data, like a coronavirus diagnosis for example, does this influence management and response?

From the air pollution and climate change perspective, what is interesting is that there has been a huge government response to COVID-19, which has virtually closed down the economy and changed the way people live, and at the moment in Australia there have been around a hundred deaths. That is tragic for the families and I completely support the Governments response to the Covid-19 pandemic.  But if you look at the number of premature deaths from the fires [417], or the annual number of deaths from air pollution in Sydney estimated to be around 420 deaths per year, one questions is: why is the government willing to take such a huge response to COVID, and not to urban air pollution or other environmental risk factors that could have substantial health effects – like climate change? And one of the differences may be related to the fact that if someone dies of COVID we know who that person is, we know their name. One difficulty with many environmental risk factors for health is that the environmental factor that had a major contribution to the timing of their death, or their admission to hospital, is not recorded on the health record for that person. This can make it more difficult to convince people and politicians that these health effects are real, and that the magnitude of the effects is big, and that we need to take action to reduce that large health burden.

This definitely highlights the critical importance of studies like yours, in drawing that direct link between the impact of these deaths and these large-scale environmental events, and hopefully, in motivating better preventative strategies and responses.

In the future, when we eventually, hopefully, move to a non-carbon based economy resulting in generally lower air pollution emissions, catastrophic fire seasons like what we experienced in 2019/20 could become the major source of air pollution exposure that people experience in their life. And so, we need to make sure that we not only manage the direct effects of the fires, and the Rural Fire Services and fire authorities do a great job with that, but we also need to manage the health burden of smoke exposure, and try to reduce that exposure. This means taking action to reduce the impacts of climate change which is related to the increasing frequency and severity of fires we are seeing in Australia, and globally.

We need to evaluate the risk of air pollution in the wider context of the effects of bushfire and of community safety. For example, hazard reduction burning is an important tool for reducing fire risk and managing smoke should be integral to the planning of hazard reduction programs. Close collaboration between health, environment and fire management agencies is essential for achieving the best overall outcomes for community wellbeing.

What has been surprising from my perspective [over the past few weeks] is that most governments have embraced science in their responses to COVID-19, and this gives me hope that this acceptance of the importance of science in decision making will lead to renewed action to reduce the impacts of climate change on planetary systems and on human health.

The full study, ‘Unprecedented smoke-related health burden associated with the 2019–20 bushfires in eastern Australia’, published by the Medical Journal of Australia is co-authored by Nicolas Borchers Arriagada, Andrew Palmer, David Bowman, Geoffrey Morgan, Bin Jalaludin and Fay Johnston, and can be accessed here.

This article is part of our Corona and Climate Series, an ongoing collection of opinion pieces from leading experts in the SEI community. In a time of intersecting planetary crises, this series analyses the parallels between ecological and epidemiological crisis, focussing on questions of resilience, adaptation and justice on local and global scales.

Geoff Morgan has more than 15 years experience in epidemiological research, as well as environmental health policy and education. His research address important health issues in both environmental health research and health services research, specialising in the use of state of the art biostatistical and geographical information system techniques applied to routinely collected health data linked to small area level socio-demographic and environmental risk factors. The results of his research have been translated into environmental health and health services policy and his current work includes epidemiological studies into: modelling service delivery for rural and remote birthing services in Australia; the health effects of smoke from various sources including bushfires and wood heaters; the effects of drinking water quality on health; the health effects of heatwaves; the relationship between neighbourhood walkability and health; the impact of care coordination on the management of patients with chronic disease. He has a joint appointment with the University Centre for Rural Health – University of Sydney and the North Coast Public Health Unit.