From frostbite to heatwaves
For Professor Ollie Jay, Director of HHRC, the path to becoming a global leader in heat-health research wasn’t exactly linear.
“My PhD was actually looking at frostbite,” he says with a laugh. “I went from studying the cold to spending my days simulating heatwaves. But when I saw how little collaboration there was between physiology and public health, I realised there was a real opportunity to bridge the gap. Extreme heat is the number one killer when it comes to natural hazards, and yet the advice people were getting wasn’t evidence-based. That’s what brought me to Sydney in 2014 - to build something that could change that.”
Since then, HHRC has become a world-leading hub, influencing everything from global health policy to local community guidelines.
“As of May 2024, our research was officially adopted by the World Health Organisation,” says Professor Jay. “We’ve also rewritten the heat-health guidelines for NSW Health and the Victorian Department of Health, and partnered with Google so that during a heatwave, evidence-based cooling advice pops up in Google Maps and Chrome for countless people worldwide.”
What heat does to the body
The Centre’s work is grounded in a simple but sobering fact: heat puts immense strain on the human body.
“When your core temperature rises, your heart has to work harder, your kidneys are under stress and if you can’t cool down, that can be fatal,” Professor Jay explains. “The reason we test everything in the climate chamber is so we can identify simple, effective ways to reduce that strain and translate it into public health advice.”
One of HHRC’s most significant findings is its “fan-first” cooling approach. “If Australians adopted it, we estimate it could cut electricity use for cooling by up to 70%,” Professor Jay says. “You feel just as cool, but you use far less energy. It’s good for people and for the planet.”
Alongside its life-saving work on public health, the HHRC is also shaping international policies at the intersection of sport and extreme heat. The Centre’s expertise has informed guidelines for major sporting events, including the Australian Open, where heat policies determine how athlete safety is managed in soaring summer temperatures.
We should be talking about heat the same way we talk about bushfires. Just as you’d have a fire plan, people with chronic conditions need a heatwave plan.
Dr Georgia Chaseling
Senior Research Fellow at HHRC
The vulnerable are most at risk
Dr Georgia Chaseling (PhD ‘19), Senior Research Fellow at HHRC, co-leads the centre’s Ageing and Chronic Diseases theme. Her work focuses on why older Australians and those with heart disease are at such high risk.
“There’s plenty of epidemiological evidence showing people with cardiovascular disease are more likely to be hospitalised or die in extreme heat,” she says. “But until recently, no one really understood why. Our studies show that for those who already have reduced blood flow to the heart, heat adds another layer of strain. They simply don’t have the physiological reserve to cope.”
Dr Chaseling is also working with cardiac rehabilitation programs to fill what she calls “a major gap in awareness and resources.”
“We published a survey that asked cardiac rehab clinicians what they know about heat, what they tell their patients, and whether they think their patients understand the risks,” she says. “It was overwhelming. Clinicians told us, ‘We know this is a problem, but we have no resources to give our patients.’ Many also felt their patients had no idea how heat affects their heart health.”
“That’s why we need proper education and materials - not just for clinicians, but for patients too. We should be talking about heat the same way we talk about bushfires. Just as you’d have a fire plan, people with chronic conditions need a heatwave plan: who to call, where to go, and what steps to take to stay safe.”
Pregnancy and heat: a critical frontier
PhD student Megan Tiong (BAppSci ’22) is bringing another vulnerable group into focus: pregnant women. She is conducting her research as part of the HEaT INFORM Pregnancy Study, comparing how pregnant and non-pregnant women regulate heat while performing light exercise in HHRC’s climate chamber.
“The human body’s resilience and ability to respond to its environment is so fascinating to me,” says Tiong. “But in a world that’s only getting hotter, it’s important that people are kept safe during all of their life stages.”
A typical trial, she explains, is hands-on. “I’ll set the climate chamber, meet the participant, fit the monitoring equipment, and observe them through the session. We might test cooling strategies or hydration. Afterwards, I make sure they’re feeling okay, book them a taxi home, and then it’s onto cleaning and data analysis.”
Common heat myths and practical tips
Beyond her research, Tiong wants to bust some persistent myths.
“There’s no one-size-fits-all solution,” she says. “But if there’s one thing I’d tell my fellow students, it’s this: use a fan. It’s far better for the environment than air conditioning, and if you pair it with strategies like skin-wetting, it works just as well.”
She also points out the hidden ways heat affects student life. “We often find it difficult to sleep during hot weather and that can really impact cognitive performance and concentration,” she says. “Being aware of this and planning ahead by hydrating and knowing where the cool spots are can make a big difference.”
When asked for their top advice for families, Professor Jay and his colleagues mention a few essentials to consider:
- Move air, don’t just chill it: “Fans, combined with skin-wetting, are incredibly effective,” says Professor Jay
- Stay connected: “Reach out to others if you live alone and check in on your elderly relatives,” Dr Chaseling says. “Social contact can save lives in a heatwave.”
- Plan ahead: “Control what you can,” Tiong adds. “Hydrate before heat hits and know your local ‘cool zones’ - whether that’s a library or shopping centre.”
And for parents of babies, Professor Jay has a practical tip. “If you’re covering a pram with a muslin cloth, make it damp and add a small fan. It can reduce the temperature inside by up to nine degrees. That’s the kind of small, evidence-based change that keeps babies safe.”
The future of heat-health research
As climate change continues to wreak havoc around the world, the HHRC team says their work is only just beginning.
“We need sustained investment in infrastructure, it would be great to get another climate chamber and funding for field trials,” Professor Jay says. “We know what works - we just need to scale it up.”
Dr Chaseling agrees. “This research is urgent. Climate change isn’t waiting for us to catch up. If we want to protect the most vulnerable, from heart patients to pregnant women, we need to act.”