Bushfire smoke from ‘Black Summer’ killed hundreds: Inquiry

Evelyn Lewin

28/05/2020 12:50:07 PM

Resultant air pollution saw a rise in respiratory issues and out-of-hospital cardiac arrest.

Smoke in Australian cities
Bushfire smoke pollution leads to exacerbation of respiratory conditions and has a ‘clear’ link to sudden out-of-hospital cardiac arrest. (AAP)

Smoke from the bushfires that raged throughout Australia’s 2019−20 summer caused an estimated 445 deaths.
Meanwhile, 3340 people were admitted to hospital due to cardiac and respiratory problems, and 1373 people attended emergency departments (EDs) as a result of asthma complications.
Furthermore, 80% of the Australian population was affected by smoke from the fires, which burned in six states across six months.
Associate Professor Fay Johnston from the Menzies Institute for Medical Research at the University of Tasmania told the Royal Commission into National Natural Disaster Arrangements the premature loss of life and increased hospital admissions had generated an estimated $2 billion in associated health costs.
Associate Professor Louis Irving is the Director of Respiratory and Sleep Medicine at the Royal Melbourne Hospital.
He told newsGP the particles in air pollution stemming from bushfire smoke that are of most concern are PM2.5, particulate matter 2.5 microns or smaller.
Those particles are predominantly composed of carbon in bushfire smoke. But, according to Associate Professor Irving, the severity of the 2019−20 bushfires meant the pollution spread far beyond local communities affected by the fires themselves.
It consequently affected ‘millions’ of people.
Such spread also altered the composition of the air pollution.
‘As pollution travels, it picks up other [matter],’ Associate Professor Irving said.
‘So it might have been relatively “clean” bushfire carbon particles at the site of the bushfires, but by the time it got to Melbourne or other cities, it also picked up some diesel pollution, some industrial pollution, [and] some pollens.
‘So the pollution isn’t necessarily just wood-fire smoke anymore, it’s a mixture of pollution.’
That mixture of pollution then acts as an irritant particulate and a chemical stimulus for inflammation in the lung. This leads to effects on the respiratory system, causing exacerbations in people with underlying respiratory issues such as asthma, chronic obstructive pulmonary disease (COPD) and bronchiectasis.
Associate Professor Irving co-authored a study led by Clare Walter, published in Respirology in March, which backs that notion. That research discussed the existing Australian evidence base surrounding landscape fire smoke and its negative health effects.
It found ‘significant’ positive associations between smoke event days and COPD and asthma hospital admissions, and emergency department (ED) attendances.
However, air pollution related to bushfire smoke does not only affect the respiratory system, it also leads to a spike in cardiac events.
‘That effect is a very worrying one,’ Associate Professor Irving said.
He said PM2.5 can be absorbed into the bloodstream and have inflammatory effects.
‘There’s a whole lot of data about this, including from the Framingham Heart Study in the US, where they showed that people exposed to PM2.5 have a higher C-reactive protein [CRP] in their blood than people who haven’t been exposed [to such ultra-fine particles],’ Associate Professor Irving said.
‘It’s been very clearly shown that [after such exposure] there is an increase in sudden cardiac events.’
Further Australian studies have also found a link between such smoke and out-of-hospital cardiac arrest (OHCA).
‘When there’s a sudden increase in PM2.5, about 8−10 hours later there is an increase in sudden cardiac death outside hospital,’ he said.
‘These findings have been replicated in Japan, Europe, America and China.’
This outcome is most likely to affect older people and those with an underlying predisposition to cardiac disease.
‘Clearly it’s not affecting everyone on the street,’ Associate Professor Irving said.
‘It’s affecting at-risk groups.’
Associate Professor Irving believes there are many important health messages to be gleaned before Australia’s next bushfire season, when GPs can expect to see more patients with exacerbations of underlying respiratory conditions such as asthma, COPD and bronchiectasis.
Such patients should be advised to have their medication checked and ensure their asthma action plans are up to date.
‘GPs will also need to be aware there will be some older people who may run the risk of an acute cardiac event,’ Associate Professor Irving said.
General health advice should also include discussions about the use of facemasks to reduce air pollution, continuing regular medication throughout the season, and staying indoors when possible.
An article published in the Medical Journal of Australia (MJA) in March mentioned further strategies to help reduce risk. These included reducing strenuous physical activity outdoors and paying consideration to the idea of temporarily relocating to a different area if needed.
‘Working towards ambitious climate-change mitigation targets is an essential long-term strategy for managing the underlying causes of the increasing bushfire risk in Australia and overseas,’ the authors wrote.
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