Extreme weather related injuries in Australia over the last decade

Most injury hospitalisations occur over summer

Most injury hospitalisations related to extreme weather occur between November and March of the next year (Figure WI.2). Extreme weather events can vary geographically but, in recent years, Australia has witnessed large multi-state extreme weather events, such as the:

• 2019-20 bushfires in Victoria, South Australia and New South Wales
• 2022 flooding across Queensland and New South Wales (BOM 2020, 2022a).

A variety of extreme weather events or natural hazards have occurred, often of prolonged duration or within short time frames of each other (Figure WI.2). Multi-state, sustained and sequential events can compound harm to human health and stretch available health and emergency management resources, highlighting the need for cohesive national approaches to mitigate the effects of extreme weather conditions (Beggs et al. 2022).

Figure WI.2: Most injury hospitalisations occur over summer

Note: BOM Special Climate Statements highlight notable climatological events, many of which (but not all) had substantial community impacts. They do not align perfectly with injuries; for example, a winter warm spell is unlikely to have major health impacts.

Source: AIHW National Hospital Morbidity Database and BOM Special Climate Statements.

Climate drivers affect injury hospitalisation patterns

Many factors influence Australia's weather. One of the largest drivers of annual variation is the El Niño-Southern Oscillation (ENSO) cycle (BOM 2021). El Niño is driven by warmer water surface temperatures in the central eastern Pacific Ocean, while La Niña occurs when the water surface temperatures are higher in the western Pacific. Both ENSO phases can occur in a calendar year.

In Australia, El Niño typically drives periods of:

• reduced rainfall
• warmer temperatures
• increased fire danger in south-east Australia.

La Niña is normally associated with:

• above average rainfall
• cooler daytime temperatures
• increased chance of tropical cyclones and flood events.

Extreme weather events leading to injury can occur in either phase of the ENSO cycle; however, some of these events are more likely under certain prevailing conditions.

Across Australia, more injury hospitalisations related to extreme weather were recorded for El Niño and La Niña years than for years with predominantly neutral ENSO drivers (Figures WI.3, WI.4; BOM 2024). In both El Niño and La Niña years, injury hospitalisations were predominantly recorded in summer.

• The highest number of recorded injury hospitalisations related to extreme weather (1,108 hospitalisations, crude rate of 4.4 per 100,000 people) occurred during Australia's last El Niño year (2019-20) (Figures WI.1 and WI.4) - 871 of these hospitalisations occurred between November 2019 and February 2020 (Figure WI.4).

Figure WI.3: Injury hospitalisations rise during El Niño and La Niña years

Source: Data sourced from the AIHW National Hospital Morbidity Database and the BOM ENSO Outlook alert system (BOM 2024).

Figure WI.4: Most injury hospitalisations occur during summer months across ENSO phases

Source: Injury hospitalisation data sourced from the AIHW National Hospital Morbidity Database; the ENSO Outlook is from the BOM ENSO Outlook alert system (BOM 2024).

Most injury hospitalisations are due to extreme heat

Extreme heat was responsible for 78% of all injury hospitalisations related to extreme weather over the last 10 years (7,104 hospitalisations, an average number of 710 per year and an average crude rate of 2.9 per 100,000 people). Heatwaves are Australia's most dangerous natural hazard in terms of loss of life (Coates et al. 2022;DAWE 2015).

Extreme heat events are occurring more often, earlier in the year, more intensely and for longer (BOM and CSIRO 2022; Steffen et al. 2014). The Bureau of Meteorology describes a heatwave as 3 or more days of unusually high temperatures for a location compared with the local climate and previous and expected weather (BOM 2022b). The Bureau also classifies heatwaves by intensity, using the excess heat factor, which warns how severe a heatwave will be for the local population to survive.

Exposure to prolonged or severe natural heat can result in physical conditions ranging from mild heat stroke to death (DEA 2023). High temperatures are also linked to irritability, fatigue and decreased performance, which can increase the risk of injury by affecting behaviour, such as operating vehicles and power tools (Xiang et al. 2014).

Across Australia, the rate of injury hospitalisation related to extreme heat exceeded 3 per 100,000 people in 2013-14, 2016-17, 2018-19 and 2019-20 (Figure WI.5). This rate remained consistently higher than hospitalisations due to any other hazard type between 2012 and 2022.

Excluding Tasmania, exposure to excessive heat was the most common cause leading to injury hospitalisation across states and territories. In Tasmania, it was the second most common cause, after extreme cold (AIHW 2023). Since 2000, heatwave deaths in Australia have been concentrated in events that largely affected Victoria and South Australia (Coates et al. 2022).

Figure WI.5: Extreme heat caused the most injury hospitalisations

Source: AIHW National Hospital Morbidity Database

Injury hospitalisations reflect only counts of direct impacts of heatwaves, with indirect health impacts, or lag effects, being potentially far greater and lasting longer (Steffen et al. 2014). Indirect impacts include worsening of pre-existing medical conditions, such as cardiac or renal disease, through effects such as:

• increased stress on the heart
• dehydration
• interactions of heat with certain medications (Zhang et al. 2022).

Other indirect consequences of heatwaves include those related to power outages (which disrupt air conditioning, and the refrigeration of food) and increased intoxication. Many indirect effects of heatwaves may not be captured by the existing hospital coding systems which inform this article.

Bushfires are a natural hazard related to hot and dry conditions

Australia is one of the most fire-prone countries in the world and the frequency of dangerous fire weather days conducive to extreme bushfires is increasing (BOM and CSIRO 2022).

Weather-related factors (including high temperatures, low humidity, lack of recent rain, and strong winds) can contribute to increased risk of bushfire danger. Bushfires also require a fuel load (which increases when vegetation dries out) and an ignition source, which can be either natural (such as a lightning strike) or human (such as discarded cigarettes, electrical faults or deliberate ignition).

Hence, bushfires frequently occur in conjunction with extreme weather events such as heatwaves, droughts or storm activity (when there may be lightning strikes and high winds).

Bushfires were responsible for 10% of all injury hospitalisations related to extreme weather over the last 10 years (894 hospitalisations, an average number of 89 per year and an average crude rate of 0.4 per 100,000 people per year) (Table WI.2). In 2019-20, there were 174 bushfire-related injury hospitalisations,107 more cases than in 2018-19, partly because of multi-state bushfires.

	Heat	Cold	Bushfires	Rain and storms	Total
El Niño	2.94	0.29	0.44	0.14	3.81
La Niña	2.86	0.31	0.27	0.14	3.57
Ratio - El Niño:La Niña	1.03	0.94	1.64	1.00	1.07

Source: AIHW National Hospital Morbidity Database.

Note: Data for 2 ENSO neutral years are excluded from this table. A ratio of more than 1 indicates higher injury hospitalisation rates due to a particular event during El Niño years compared with La Niña years. The closer the ratio is to 1, the less difference there is in rates between El Niño and La Niña years.

Injury reporting counts acute hospitalisations and deaths, which are only 2 of the more extreme health impacts of bushfires (AIHW 2020). Minor injuries may be treated without hospitalisation, while delayed or repeat presentations may occur from longer term health impacts.

The 2 most common injuries that result in hospitalisations related to bushfires are smoke inhalation and burns:

• Bushfire smoke inhalation leads to both acute and longer term health impacts (Rodney et al. 2021).
• Burns in bushfires can result from flames, radiant heat or ember attacks.

Hospitalisations for injury related to rain and storm events are difficult to measure

Rain and storm events are often interrelated. They include thunderstorms, cyclones and heavy or prolonged rainfall, which can lead to riverine or flash flooding and landslides.

Acute injuries

Intense or prolonged rainfall, floods and storms can directly cause various types of acute injuries, including:

• drowning (Peden et al. 2017)
• falls due to slippery surfaces or increased trip hazards
• contact with objects such as floating debris, submerged objects, trees or wind-borne objects (Way and Balogh 2022)
• bites and stings from displaced animals such as snakes (EPA Victoria 2022)
• burns, cardiac arrest and respiratory complications resulting from lightning strikes
• exposure to electric current from powerlines or water-affected electronic devices.

• Indirect consequences

  Indirect consequences include:

• injuries caused by transport-related accidents, including on land or water (Transport for NSW 2023)
• worsening of symptoms or death from non-communicable diseases such as cancer, cardiovascular diseases and diabetes owing to disruptions to health-care services (Ryan et al. 2015)
• communicable diseases from contaminated floodwaters (EPA Victoria 2022) or from spreading vector habitat following heavy rains (Pendrey and Martin 2023)
• injuries subsequent to displacement, clean-up activity and environmental upheaval caused by severe rains or storms.

Rain- and storm-related injuries are particularly challenging to identify in administrative hospital data since the external cause of injury may be recorded as transport or drowning (for example), rather than as being rain and storm related. Case counts for this type of injury potentially underestimate the number of hospitalisations more than for other types of injuries related to extreme weather.

There were 348 hospitalisations for rain- and storm-related injury recorded between 2012 and 2022 (4% of total, an average of 0.1 injury hospitalisations per 100,000 people per year across the decade). During 2021-22, Australia's latest La Niña year, there were 60 hospitalisations for rain- and storm-related injury, which is:

• the highest number for any of the 10 years examined (10-year average was 35 injury hospitalisations)
• the equal highest crude rate per 100,000 people of the 10 years examined (0.2 in both 2014-15 and 2021-22).

Extreme cold hospitalisations are consistent over time

There were 773 injury hospitalisations (8% of total, 0.3 per 100,000 people) related to extreme cold recorded between July 2012 and June 2022 across Australia. Extreme cold hospitalisations were consistent over the past decade (Figure WI.5).

Vulnerability to injuries

Age, sex, occupation, poverty and pre-existing health conditions all make people more vulnerable to sustaining injuries related to extreme weather.

Vulnerable population groups

Certain population groups (depending on where they live and their access to resources) have a reduced capacity to avoid or reduce the impacts of extreme weather conditions; this places them at greater risk of injury related to extreme weather as well as other health consequences (Byrne et al. 2016; Peden et al. 2023; Tanner et al. 2013; Varghese et al. 2018).

Vulnerable occupations

People in occupations where large amounts of work occur either outdoors or in poorly ventilated environments are disproportionately exposed to natural hazards and extreme weather conditions, as are emergency service personnel required to enter areas where natural hazards have occurred (Fatima et al. 2021; Kjellstrom et al. 2016).

Urban heat island effect

As well, there is the urban heat island effect, likely to affect city inhabitants. This phenomenon occurs when heat is absorbed by building materials and surfaces such as bricks, roads, carparks and concrete and then radiated into the surrounding area. This effect increases the risk of injury hospitalisations related to extreme heat for people in cities (Steffen et al. 2014).

Vulnerability to extreme heat

Of hospitalised injury cases related to extreme heat in the 3 financial years from 2019 to 2022:

• 1 in 3 were for people aged 65 and over (37% or 793)
• 1 in 5 were for people aged 25-44 (22% or 478) (AIHW 2023)
• nearly twice as many were for males as females (1,434 versus 716).

This difference was most notable among people aged 25-44 and 45-64, where over twice as many males were hospitalised due to extreme heat as females. This may reflect the higher numbers of males in outdoor-based workforces, such as tradespeople and agricultural workers (Fatima et al. 2021).

Monitoring the impacts of extreme weather on Australia's health

Monitoring the health impacts of climate change is important to inform policy responses, such as those outlined in the National Health and Climate Strategy (Department of Health and Aged Care 2023). This strategy commits to exploring options to develop a framework to monitor indicators of the health impacts of climate change.

The AIHW is actively working with national stakeholders to develop baseline reporting of key data and information on how climate and the environment affect the health of people in Australia - including the emerging area of surveillance of injuries related to extreme weather. This article presents baseline findings to inform future surveillance of such injuries. Improving surveillance over time is expected to lead, in turn, to improvements in detecting, preventing and preparing for the health impacts of extreme weather conditions across Australia.

Total injuries related to extreme weather - an underestimate

Information presented in this article on these findings, however, underestimates total injuries related to extreme weather for the following reasons:

• It is challenging to identify injury directly caused by weather in currently available hospital data sets. Available data do not preclude non-weather-related causes of injuries not related to weather. For example, hypothermia is counted where there is exposure to extreme cold, but this may include cases where the exposure was related to swimming.
• This article is limited to cases where it is reasonable to conclude injury was directly related to exposure to one of the 4 extreme weather conditions discussed (see Table WI.1).
• Only acute injuries where hospitalisation occurs are counted, excluding emergency department, general practitioner, or emergency service presentations.
• Causes of injury are multifactorial, but only the primary cause reported in hospital records is considered in this article. This means indirect injuries, for example, from road traffic accidents that occur due to adverse weather conditions, are excluded due to the primary external cause of injury being recorded as transport.

Conclusion

Injuries related to extreme weather mirror climate drivers, and are occurring across Australia, often affecting multiple states and territories at any one time. They disproportionately affect population groups such as the economically disadvantaged, older people, outdoor workers and people with pre-existing health conditions. They represent the 'tip of the iceberg' of the overall health impacts of a changing climate and are projected to contribute an increasing burden to Australia's health system over time.

Surveillance of injury caused by extreme weather is evolving as climate change continues to affect public health. Injury surveillance may provide early indicators of the broader impacts of extreme weather on Australia's health and health systems; however, challenges remain in accessing sufficiently detailed data to enable effective monitoring. Hospitalisations alone do not capture the full health impacts of extreme weather; hence, as already indicated, this article presents an underestimate of injuries related to extreme weather.

The AIHW is working alongside multiple stakeholders to improve the collection and reporting of injury-related hospitalisations and deaths. This is important both for monitoring injuries related to extreme weather and for preparing health systems to cope with future demand.

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