Heatwaves have been a feature of the northern hemisphere's summer and are predicted to be an issue in Australia this year too. (Getty Images: Andrew Matthew)
A new global study suggests older people may face serious health risks from heat at much lower temperatures than previously understood.
The study found the temperature at which people age 60 and older could "no longer maintain a stable core temperature" was roughly 4.7–7.5 degrees Celsius lower than for young adults.
Researchers say there is a need for targeted, age-specific action plans and warning systems to protect older people.
As Australians prepare to swelter through a hot El Niño summer, the risk of heat stress also rises.
When we age, our bodies are no longer able to cope with heat as well as they once did.
We sweat less, making it tougher to cool down; our hearts do not pump blood as efficiently and we are more likely to have chronic health conditions — such as diabetes — which make it harder to handle hot weather.
But according to a new study, published today in The Lancet Planetary Health, the impacts of heatwaves on people over the age of 60 have been underestimated.
The human body can only take so much heat before it starts to cook from the inside. See how Margaret, Harry and Kim fair during heatwaves across Australia.
US researchers found people above this age faced serious health risks from heat at much lower temperatures than previously understood.
The study's lead author, Qinqin Kong from Stanford University in California, said it was important to understand how older people tolerated heat in different locations as the world was getting hotter and people were living longer.
The global study found the biggest future risk was in tropical and subtropical regions, but Australia's hottest regions, such as the Top End and Kimberley, were also of concern.
Dr Kong's team looked at the heat limits in three specific age groups — young adults, middle-aged people and older adults — and plotted around the world how well each demographic would cope over a year in different climate warming scenarios. Scenarios ranged from 1.5 to 4 degrees Celsius warmer than pre-industrial levels.
Researchers say there is a need to develop heat emergency plans and improve access to cooling as the world warms. (Pexels: Kindel Media)
Most previous studies, Dr Kong said, applied the heat limits for healthy young adults to all age groups, which overlooked the "vulnerability" of older people and underestimated future health risks.