Bush/landscape fires

A population-based study in WA analysing hospital admissions in Perth in 2015-2017 and smoke exposure using a model tracking PM2.5 levels during 1700 bushfires and burn offs found that following exposure to high PM2.5 (12.60 mcg/m3 or higher) there was:
– 16% (RR 1.16, 95% CI 1.00 to 1.35) increase in hospital admissions on the same day as exposure
– 93% increase in asthma hospitalisations the next day (lag of 1 day) for children
– 52% increase in asthma hospitalisations on a lag of 3 days in low socio-economic groups.

Healthcare sector emissions in Australia 2023,
– Australia is ranked eleventh highest in the world in terms of the nation’s health care sector position with respect to its per capita greenhouse gas emissions
– In 2020, Australia’s total emissions were 28.9 Mt, which includes emissions from a range of greenhouse gases that are emitted directly by the health sector, and emissions resulting from the demand of goods and services for running health care operations.
– there has been a 30% increase in total emissions in 2020 and a 28% increase in per capita emissions from 878.3 kg per capita in 2019 to 1125.2 kg per capita in 2020, compared to 2019.

PM2.5 air pollution in Australian cities between 2000 and 2023, MJA-Lancet Countdown report 2023
– The average city exposure in Australia has generally declined over time but has major fluctuations as a result of bushfires and dust storms
– Some states experience significant seasonal variations — due to the dry season in the Northern Territory and the use of wood heaters in the cooler southern regions
– The annual average PM2.5 concentrations in Australian cities were lower than in cities from many other countries (which can be as high as 35 μg/m3 annual average) but are still above the latest WHO annual air quality guideline of 5 μg/m3 but mostly below the Australian advisory reporting standard of 8 μg/m3

Increasing exposure to bushfires in Australia
After the 2019–20 Black Summer bushfires, Australians have been exposed to lower bushfire danger conditions. Nevertheless, the overall trend shows an increase over time in the exposure to very high or extremely high bushfire danger, with average annual exposure in the past ten years (2013–2022) considerably increasing to 33.6 days per person from 27.5 days per person in the previous ten years (2003–2012).

This provides:
– review of the impact of Landscape Fire Smoke (LFS) exposure
– greater impact on vulnerable groups, particularly older people, pregnant woman and Aboriginal and Torres Strait Islander peoples
– development of asthma on the background of risk factors
– advice for asthma management, smoke mitigation strategies and access to air quality information, that should be implemented during periods of LFS

Longitudinal study examined the experiences and health impacts of prolonged wildfire (bushfire) smoke exposure in adults with severe asthma during the 2019-2020 Australian bushfire period.

The bushfires that swept across Australia in 2019–2020 resulted in 33 deaths, destruction of over 3,000 houses and millions of hectares. Bushfire smoke exposure was significantly associated with an increased risk of respiratory morbidity. Nationally, hospitalisation rates increased for asthma and COPD coinciding with increased bushfire activity during the 2019–20 bushfire season. For asthma, the highest increase was 36% in the week beginning 12 January 2020 (2.4 per 100,000 persons) compared to the previous 5-year average (1.7 per 100,000 persons).
For Emergency Department presentations, asthma saw the highest increase of 44% in the week beginning 12 January 2020 (4.7 per 100,000 persons compared to the previous bushfire season (3.3 per 100,000 persons).

Nicolas Borchers is supported through a PhD scholarship from AA.

Research based in Tasmania, given the high rate of wood fire heater use during winter which produced fine particulate matter, harmful to human health and particularly people with asthma or other chronic conditions. The researched aimed to estimate the historical health impacts and health costs from PM2.5 produced by wood heater smoke and landscape fire smoke (includes wildfires and hazard reduction burning)
Method
– Modelling study
– health impact assessment to estimate the number of cases and costs due to premature mortality, cardiorespiratory hospital admissions, asthma ED visits
– analysed historical air pollution, temperature and assessed where PM2.5 was due to landscape fire or wood fire heaters
– between January 2010 and December 2019
– characterise days an unpolluted or polluted, and if polluted determine whether they were primarily woodfire heater and landscape fire smoke
Results
– estimated 69 deaths, 86 hospital admissions and 15 asthma ED visits each year, with 74% of impacts attributable to wood fire heaters
– estimated yearly average health costs were $293 million for wood fire heaters, and $16 million for landscape fire smoke
– during extreme bushfire seasons, landscape fire smoke cost more than $34 million per year
– unlike wood fire heaters, landscape fire impacts are not distributed evenly from year to year, but vary according to the intensity of the bushfire season. If you exclude 2016 and 2019 from the analysis, the yearly cases drops substantially for landscape fire smoke

The purpose of this study was to conduct a systematic review and meta-analysis of the associations between short-term exposure to landscape fire smoke PM2.5 and asthma related outcomes including; hospital admissions, emergency department visits, physician visits, medication use and salbutamol dispensations. To the best of the researchers knowledge, this is the first meta-analysis to obtain summary estimates between fire smoke PM2.5 and asthma related outcomes.
From 181 initial articles, 20 were included for quantitative assessment and descriptive synthesis. Eight studies were from Australia and the USA, four studies were from Canada.
Findings
• Fire smoke PM2.5 levels are positively associated with asthma hospitalisation and ED visits for all ages and sexes
• Females and people over the age of 65 were most susceptible to the landscape fire smoke
• Short term impacts of landscape fire smoke are worse than those from multi-source urban pollution
Short-term exposure to fire smoke PM2.5 is positively associated with asthma-related outcomes, and this is association is higher than from typical multisource pollution. During short fire periods, people are exposed to higher concentrations of particulate matter.
Fire smoke PM2.5 levels were positively associated with asthma hospitalisations and ED visits for all age groups and sexes. Hospital admissions results show that smoke effects could last for multiple days, while for ED visits effects tended to occur on the same day as exposure.
There was a stronger association between fire smoke PM.25 and ED visits/hospitalisations with increasing age. Adults were more susceptible than children, and elderly more susceptible than adults. This is different to evidence related to multisource air pollution where children were most sensitive. Females were more susceptible to fire smoke than males
There is likely an association between fire smoke PM2.5 and physician visits, salbutamol dispensations and medication use in adults but the evidence available is too limited for statistically significant results.

In May 2016 there were hazard reductions burns conducted around Sydney causing smoky conditions and high PM2.5 concentrations for several days. This study assessed the impact of smoke-related PM2.5 on all-cause mortality and hospitalisations for cardiovascular and respiratory conditions in Sydney. Six days were identified as being clearly smoky. It was estimated that 14 premature deaths and 58 respiratory hospitalisations were attributable to these smoky days. This highlights the potential scale of the public health impacts when smoke affects a population of nearly 5 million people for several days.

An assessment of all-cause mortality and hospitalisations for cardiovascular and respiratory disease in Sydney between 2001 and 2013 quantified the population level health effects attributable to exposure to landscape fire events in Sydney. Verified dates for landscape fire events were located and background PM2.5 and health burden were estimated. Health Burden was estimated from death and hospitalisation incidence rates, daily PM2.5 exposure and risk estimates recommended by WHO. The results found that the health impacts of landscape fire smoke exposure during 2001-2013, was similar to a May 2016 incident every 12 months (14 premature deaths and 58 respiratory hospitalisations). Health risk estimates are likely conservative as they assumed short term, immediate impacts of increased PM2.5 but extended exposure is likely to have greater effects