'Wake-up call': Heatwave danger for over-60s underestimated, study finds

Older adults face a significantly underestimated risk from heatwaves, even at moderate global warming levels, according to a new study published in The Lancet Planetary Health. US researchers found that individuals over 60 experience serious health risks from heat at much lower temperatures than previously understood.

The study's lead author, Qinqin Kong from Stanford University, highlighted the critical need to understand how older people tolerate heat in different locations as the planet warms and populations age. The research indicated that the biggest future risk is concentrated in tropical and subtropical regions, but Australia's hottest areas, such as the Top End and Kimberley, are also of concern.

Previous studies often applied heat limits suitable for healthy young adults to all age groups, overlooking the unique vulnerabilities of older individuals. Dr. Kong explained that modeling suggests uncompensable heat, a state where the body cannot cool itself regardless of acclimatization or fitness, will become far more widespread, frequent, and imminent than previously estimated. "One of our most striking findings is that older adults face more frequent and widespread uncompensable heat at just 1.5C of global warming than young adults do even at 4C," he stated.

While there is no definitive safe exposure level for uncompensable heat due to individual differences in temperature coping mechanisms, laboratory experiments show young adults can develop heatstroke after 3–10 hours of exposure. Dr. Kong's team estimates that the temperature at which individuals aged 60 and older can no longer maintain a stable core temperature is roughly 4.7–7.5C lower than for young adults. This means the number of people facing at least 180 hours of uncompensable heat annually could be two to eight times higher than previous estimates assumed. Researchers emphasize the need for updated heat emergency plans and improved access to cooling as the world continues to warm.

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One of our most striking findings is that older adults face more frequent and widespread uncompensable heat at just 1.5C of global warming than young adults do even at 4C.