The natural environment comprises the atmosphere, land, water, oceans, and the diversity of living things (UN 2019). It provides essential resources for health and wellbeing including food, fresh water, wood and fibre, fuel and medicines. It also helps regulate weather, vegetation, soils, and the quality of water and air, and provides a range of aesthetic, cultural, recreational and spiritual services to people (Whitmee et al. 2015).

As a result of human pressure, the health of most or all of the planetary systems that provide these services is currently in decline, including some already considered irreversibly damaged (UN 2019).

This page presents a selection of evidence about the pressures on some of Australia’s major environments and their direct and indirect impacts on human health. See Built environment and health for information on the health impacts of the human-made surroundings.

2019–20 bushfires

Accumulated Forest Fire Danger Index values for spring 2019 were the highest on record over large areas of Australia. Record high values were observed in areas of all states and territories. Rainfall across the country was 62% below average making it the driest spring on record and daytime temperatures were above average to highest on record over most of Australia (BOM 2019a).

The 2019–20 bushfires were unprecedented, with 21% of Australia’s temperate forests burned compared with the 2% typical of previous major fire years (Boer et al. 2020). This page describes the health impacts of bushfires in general terms (see Bushfires); however the full health and related impacts of these bushfires won’t be known for some time. The forthcoming release, Australian bushfires 2019-20: exploring the short-term health impacts (AIHW forthcoming 2020) will describe some of the more immediate impacts of the 2019–20 bushfires on health and the health system.

Climate change and health

What is climate change?

Climate change refers to a change in the pattern of weather, which affects oceans, land surfaces and ice sheets, occurring over decades or longer (Australian Academy of Science 2019). Human activities, such as burning fossil fuels, agriculture and deforestation have resulted in an increase in atmospheric greenhouse gas (GHG) concentrations. These gases trap heat in the atmosphere, which heats the land and oceans and changes weather patterns (IPCC 2014).

Climate change affects environmental determinants of human health through a range of different pathways, from extreme weather events to infectious and communicable diseases, and availability of food and water (Ebi et al. 2018). This can result in health effects such as thermal stress, injury, vector-borne and other microbial diseases, food insecurity and poor mental health (McMichael et al. 2006). The social determinants of health are being affected by climate change (WHO 2018a).

Climate change affects some population groups more than others. Groups at greater risk include older people, children, people with chronic conditions and multimorbidity, outdoor workers, people living in rural and remote areas, those living in low-lying, flood or bushfire-prone areas, and socioeconomically disadvantaged groups.

Extreme weather events 

The extreme weather events described here include heat waves, drought, bushfires, violent storms, heavy rainfall events and flooding.

Under climate change, the intensity and/or frequency of at least the first 2 of these extreme weather events and the number of days with fire weather conditions has increased, and is projected to continue increasing (BOM & CSIRO 2018). Without adaptation and mitigation, the health impacts of these events are also likely to increase (Beggs et al. 2019; WHO 2018b). 

What are mitigation and adaptation?

Mitigation is action taken to reduce greenhouse gas emissions, such as replacing coal burning power stations with solar or wind power, and/or increasing the amount of greenhouse gases removed from the atmosphere by carbon sinks such as forests or soils (IPCC 2014).

Adaptation involves taking practical action to manage risks from climate impacts, protect communities and strengthen the economy, such as bushfire preparedness and heatwave response planning (Department of the Environment and Energy 2019; Zhang et al. 2018).

Heatwaves and very hot days

A heatwave is defined as 3 or more days of high maximum and minimum temperatures that are unusual for a location (BOM 2019b). Heatwaves are monitored by the Bureau of Meteorology (BOM 2019b).

Heatwaves are associated with heat-related conditions ranging from minor rashes and body cramps to more serious conditions such as heatstroke (severe hyperthermia). Excessive heat can also exacerbate existing health conditions such as heart disease, diabetes, and kidney disease; reduce productivity; and increase the geographic spread of vector-borne diseases and transmission of food-borne diseases such as gastroenteritis (AMA 2015).

Increases in hospitalisations and deaths in Australia have been observed during heatwaves. Consistent and significant increases in hospitalisations and emergency department presentations occurred on heatwave days compared with non-heatwave days across South Australia in 2000–2016 (Williams et al. 2018). In Victoria, there were 374 extra deaths (a 62% increase in all-cause mortality) during a heatwave from 26 January to 1 February 2009 (Department of Health and Human Services 2009).

Recent data from the Bureau of Meteorology show that 2019 was Australia’s hottest year on record, with average temperatures 1.52 degrees Celsius above the long-term average (BOM 2020). The number of days over 35 degrees has increased (BOM & CSIRO 2018), increasing the probability of heatwaves. Very high monthly maximum temperatures that occurred around 2% of the time in the past (1951–1980) now occur around 12% of the time (2003–2017) (BOM & CSIRO 2018). This increase in the number of very hot days is projected to continue under climate change (BOM & CSIRO 2018).

Bushfires

Health impacts from bushfires include immediate effects of death and trauma from the fires, as well as exacerbations of some respiratory and cardiovascular conditions.

In Australia, there were an average of 5.4 bushfire-related deaths per year between 1901 and 1964, and 10.5 per year between 1965 and 2011 (Blanchi et al. 2012)—a comparison which doesn’t take population growth into account. A large proportion of these deaths occurred in 6 individual years, including 2009, when the Black Saturday bushfires killed 173 people (The 2009 Victorian Bushfires Royal Commission 2009). In addition, an average of 174 bushfire-related injuries are estimated each year for the period 1967–2013 (Geoscience Australia 2019).

Smoke generated by bushfires can affect respiratory health over large areas, as evidenced by increased respiratory hospital admissions during bushfire events (Chen et al. 2006; Johnston et al. 2002; Kolbe & Gilchrist 2009; Morgan et al. 2010; Tham et al. 2009). See the section on air pollution for more information on smoke-related air quality.

The longer-term effects of bushfires require more research but may include deterioration of existing health conditions such as hypertension, gastrointestinal disorders, diabetes and mental illness (Clayer et al. 1985). The experience of bushfire may increase the occurrence of psychological and behavioural disorders such as anxiety, depression and substance misuse (AIHW 2011).

Based on estimates from a recent study of the impacts of the 2019–20 bushfire season, 10% of Australian adults considered their home or property was directly threatened, while over half (54%) experienced anxiety or worry due to the bushfires (Biddle et al. 2020). Reports of bushfire-associated anxiety or worry were more common in females, young people and people living in capital cities—but this last finding is thought to reflect under-reporting in rural and remote people due to cultural values of stoicism in the face of hardship (Biddle et al. 2020).

A follow-up study of psychological outcomes 5 years after the 2009 Black Saturday bushfires found that 22% of people who had been in communities highly affected by the fires were suffering probable post-traumatic stress disorder (PTSD), major depressive episode or severe distress, compared with 5.6% of people who had been in regions that were less affected by the fires. Levels of PTSD for those with any exposure to bushfires were markedly higher than for those measured in the general population (Bryant et al. 2018).

Drought

Australia is drought-prone and many areas have a dry climate. Long periods of below-average rainfall adversely affect the natural environment, and have flow-on effects for human health (AIHW 2011; Kalis et al. 2009).

Many health effects of drought have been documented globally, including malnutrition and mortality, water-related disease such as E. coli, airborne and dust-related disease, vector-borne diseases such as dengue fever, mental health effects and distress (Stanke et al. 2013).

The mental health effects of drought appear to be complex. Some studies have found associations between the health of men and drought, but women seem to be less affected. A longitudinal study (Powers et al. 2015) found that drought did not lead to poorer mental health among mid-aged Australian women.

From 2001–02 to 2007–08, people living in drought-affected areas in rural Australia had higher levels of distress than people living in urban areas (O’Brien et al. 2014). A 2012 study (Hanigan et al. 2012) found an increased risk of suicide among males aged 30–49 living in rural areas of Australia during periods of drought between 1970 and 2007.

Drought can also restrict physical and financial access to healthy foods. For example, drought was identified as the primary contributor to substantial increases in the price of fresh fruit (43% rise) and vegetables (33% rise) between 2005 and 2007 (Quiggin 2007).

Storms and floods

Health effects from storms and floods may be short-term (for example, physical trauma), medium-term (for example, the spread of vector-borne disease) or long-term (such as post-traumatic stress and depression) (Fewtrell & Kay 2008; Ivers & Ryan 2006).

A survey of the disaster-related trauma from the 2010–2011 Queensland floods and cyclones found that 14% of respondents felt terrified, helpless or hopeless following the events and 7.1% of respondents continued to experience distress months later (Clemens et al. 2013).

Like drought, storm and flood damage can also restrict food availability and increase food prices. These weather events may also have broader economic impacts. As an example, the reduced banana supply following Cyclone Yasi in 2011 resulted in a 0.7 percentage point increase in inflation (Debelle 2019) affecting the entire Australian economy.

Ultraviolet radiation

Ultraviolet radiation (UV) from the sun is essential for good health as it helps the body manufacture vitamin D (WHO 2019a). However, it is also known to cause a number of cancers, such as non-melanoma skin cancers (including basal and squamous cell carcinomas), melanoma (including melanoma in situ) and cancer of the eye.  UV may be responsible for 20% of cataracts globally (WHO 2019b).

In 2015, UV exposure was responsible for 0.8% of the total burden of disease in Australia (AIHW 2019a).

In 2017–18, an estimated 410,800 Australians had cataracts (ABS 2018).

In 2019, an estimated 15,200 new cases of melanoma and 23,700 new cases of melanoma in situ of the skin were diagnosed in Australia, while 1,700 deaths were attributed to melanoma. This compares to 8,700 cases of and 970 deaths due to melanoma in 2000 (AIHW 2019b; AIHW 2020).

Exposure to UV can be moderated by protective behaviours. However, only 47% of adults and 33% of adolescents typically employ 2 or more of these (hat, sunscreen, shade, clothing) (Cancer Australia 2019).

Biodiversity

Biodiversity is fundamentally important for human health because ‘it helps to regulate climate, filters air and water, enables soil formation and mitigates the impact of natural disasters. It also provides timber, fish, crops, pollination, ecotourism, medicines, and physical and mental health benefits’ (UN 2019).

Contact with nature also has health benefits—increased attention, energy and tranquillity, and significantly decreased anxiety, anger, fatigue and sadness are all associated with exposure to natural environments (Bowler et al. 2010). Natural places such as parks provide opportunities for outdoor recreation, spiritual and cultural heritage connection, physical, mental, and social health benefits and neighbourhood amenity (Parks Victoria 2015).

Planetary biodiversity (the range of living things) is declining rapidly (WWF & ZSL 2018) and the ‘status of biodiversity in Australia is generally considered poor and worsening’ (Cresswell & Murphy 2017), with about 1,800 species of plants and animals in Australia listed as threatened as a consequence of invasive species (particularly feral animals), habitat fragmentation and degradation, and the increasing impact of climate change (Cresswell & Murphy 2017).

Access to urban biodiversity is also becoming increasingly important to human health and wellbeing as cities continue to grow. See Built environment and health.

Air pollution

Air pollution, in particular fine airborne particles (particulate matter) known as PM2.5 can have short-term adverse impacts on human health; more research into potential longer-term impacts of PM2.5 from bushfire smoke is needed. These particulates can decrease lung function, increase respiratory symptoms, chronic obstructive pulmonary disease, cardiovascular and cardiopulmonary disease and mortality (Pope & Dockery 2006), and decrease life expectancy (Pope et al. 2009). In 2013, the International Agency for Research on Cancer classified outdoor air pollution as a human carcinogen (Jackson et al. 2016).

In 2015, nearly 2,600 (1.6%) deaths and 0.8% of the burden of disease in Australia was attributed to PM2.5 air pollution (AIHW 2019a).

People with an underlying health condition, such as asthma, chronic obstructive pulmonary disease, or cardiovascular disease, are particularly at risk from poor air quality (Jackson et al. 2016).

Thunderstorm asthma

Air pollution can sometimes result in major single health events. In 2016, a major thunderstorm asthma epidemic was triggered in Melbourne when very high pollen counts coincided with adverse meteorological conditions resulting in 3,365 people presenting at hospital emergency departments over 30 hours, and 10 deaths (Thien et al. 2018). See Chronic respiratory conditions

Air quality is monitored at 75 locations across Australia and reported nationally by the Department of Environment and Energy (NEPC 2019). Air quality in Australian cities is generally good to very good in comparison with similar developed economies, but the majority of Australian cities exceeded the PM2.5 advisory standard (25µg/m3) on at least 1 day each year during 2008–2014 (Keywood et al. 2016), due to extreme localised events (for example, bushfires and dust storms).

The air quality in New South Wales (NSW) and in the Australian Capital Territory (ACT) was greatly affected by the widespread bushfires burning in 2019–20. Figure 1 shows the daily average PM2.5 concentrations in Canberra and Sydney, January 2019 to January 2020. On January 1, 2020, a PM2.5 reading of 1197µg/m3 was recorded at Monash in the ACT—a reading almost 48 times the PM2.5 advisory standard of 25µg/m3.
 

The line graph shows the daily PM2.5 concentrations from January 2019 to the month of October 2019 remaining relatively low at both Sydney and Canberra’s air quality monitoring stations, mainly rated as ‘Very good’, ‘Good’ or ‘Fair’ air quality. From October 2019 through to January 2020, there is a dramatic increase in average daily PM2.5 concentrations in both Canberra and Sydney stations, with more days rated as being ‘Poor’, ‘Very poor’ or ‘Hazardous’ air quality.

Visualisation not available for printing

Vector-borne diseases

Disease vectors (such as mosquitoes) and disease micro-organisms (such as bacteria and viruses) are a natural part of the Australian environment.

Vector-borne diseases in Australia include Ross River virus, Barmah Forest virus, Murray Valley encephalitis, Kunjin and dengue. Cases of malaria in Australia currently occur only as a result of international travel.

Changes in climate are likely to extend the geographic spread and lengthen the transmission seasons of important vector-borne diseases and increase the likelihood of food- and water-borne disease (Bambrick et al. 2011; Jackson et al. 2016; WHO 2018b).

Since 1950, there has been a 14% increase in the main dengue mosquito’s capacity to transmit disease to humans. This is projected to increase into the future (Zhang et al. 2018). Notifications of dengue virus infections in Australia have increased over the past 30 years, from typically a few hundred annually to typically over a thousand annually (Department of Health 2015).

Bacterial and viral contamination of food and water was responsible for 57,600 disease notifications in 2019 including around 35,800 caused by campylobacteria infection, 14,700 by salmonella and 3,100 by shigella (Department of Health 2020). 

Where do I go for more information?

For more information on the natural environment and health, see: