Children who live in the outer suburbs of Australia’s four biggest cities are twice as likely to have asthma as those living in inner city areas, according to a new study based on health data captured in the last Australian Census.
The data was gathered after Australians completing the 2021 Census were asked for the first time to share information about long-term health conditions, to help researchers map patterns of chronic disease across the country.
A team led by geospatial modelling expert Associate Professor Ewan Cameron – from The Kids Research Institute Australia and Curtin University – combined the data with cutting-edge statistical modelling and satellite imagery to intricately map the distribution of childhood asthma and look for environmental or other risk factors.
“We took the data for the four largest cities – Sydney, Melbourne, Brisbane and Perth – and focused on asthma to try and figure out what risk factors could predict spatial patterns of occurrence in children aged 5–14 years,” Associate Professor Cameron said.
Top Left: Melbourne, Top Right: Perth,
Bottom Left: Sydney, Bottom Right: Brisbane
Image credit: The Kids Research Institute Australia
“Going in, we thought the inner city might have the most childhood asthma because of heavy traffic flow and air pollution but instead, the pattern we see is one of increasing asthma risk towards the outer areas of cities. The suburbs, with 12 per cent prevalence, had twice the rate of childhood asthma as the inner city (6%).”
Associate Professor Cameron said this pattern was witnessed uniformly across all four cities, with socioeconomic status explaining at least half of the stark spatial variation, and combined climate factors and outdoor air pollution accounting for the other half.
“In many ways it was surprising just how similar all the cities were,” he said. “We found that in every city there was that same trend – increasing prevalence from the wealthier inner-city suburbs to the poorer outer-city suburbs.
For Perth and Sydney, for example, when you look at the maps you immediately see it’s much lower in the more advantaged inner, northern and beach suburbs compared to suburbs that are more inland.
“We know from earlier studies, including the Raine Study in Western Australia, that the risk of developing asthma is strongly shaped by socio-economic factors.
“These factors include higher rates of chronic family stress and poor housing quality, including dampness and poorly ventilated gas stoves, as well as dietary and obesity factors.
“People in lower socio-economic areas, many of whom are renting, often lack the means to alleviate these issues and may have poorer access to health care support for asthma management.”
Associate Professor Cameron said the findings highlighted the challenges faced by government and health authorities tasked with fighting Australia’s childhood asthma epidemic.
However, they could be used to plan the locations of new asthma clinics and guide policy interventions such as providing financial assistance to convert cooktops from gas to electricity and install high-efficiency rangehoods and ventilation that could eliminate cooking gases or dampness in the home.
“By revealing where asthma risk is highest at a fine level of precision – down to neighbourhood block size – we can identify the local government areas that need the most support,” he said.
“This means we can target interventions and policies to help those most at need and have the greatest impact.”
The study also showed the significant role played by climate and environmental factors, after the team used satellite imagery to investigate the levels of different pollutants around each city, vegetation, and temperature and rainfall variation.
“We do find there’s a contribution from environment – places that experience large daily temperature variations tend to have higher risk of asthma. More extreme weather can be a factor in triggering asthma,” Associate Professor Cameron said.
The striking socioeconomic gap in child health witnessed within the study was also seen across other diseases – findings the team will reveal in future publications.
“The pandemic in particular exposed a lot of these health inequities between wealthier and poorer parts of the country,” Associate Professor Cameron said. “Our study reveals we still have a lot to do to give children an equal start in life.”
The team will repeat their analysis following the 2026 Census.
“We’re excited about getting the results from the next round – this will give us a new time point to mark any changes in chronic disease prevalence and, in combination with insights from other key surveys and datasets, help us to strengthen the evidence around spatial health inequalities in Australia’s major cities,” Associate Professor Cameron said.
The paper, A health inequality analysis of childhood asthma prevalence in urban Australia, was published in the Journal of Allergy and Clinical Immunology and can be read here.
Associate Professor Cameron is a member of the Geospatial Health and Development team at The Kids Research Institute Australia and an Associate Professor with the School of Population Health at Curtin University. He undertook this research with the support of a Stan Perron Charitable Foundation People and Platforms grant, and in collaboration with students visiting from Princeton University as part of an internship program.
About asthma
Asthma is a lifelong condition caused by narrowing of the airways when they become inflamed. Australia has one of the highest asthma rates in the world, affecting 8.7 per cent of children aged 1–14 years.