A recent study published in The Lancet Public Health has revealed that people aged 60 and over face severe health dangers from extreme heat at significantly lower temperatures than previously estimated. As global temperatures continue to rise, older adults are expected to experience the most significant impact from frequent, sustained heatwaves.
The research, led by health academics at Stanford University in California, highlights the prevalence of uncompensable heat stress (UHS), a condition where the human body loses its ability to regulate its internal temperature. Without the ability to cool down, individuals are at risk of serious health complications, including death. The authors noted that when age-stratified vulnerability is properly accounted for, it becomes clear that intolerable heat affects a far larger population for longer durations than prior models suggested.
Biological factors make older adults inherently more vulnerable to heat. As people age, they tend to sweat less, their hearts must work harder under thermal stress, and their blood vessels are less capable of widening to facilitate cooling. Previous scientific studies often relied on heat thresholds derived from younger populations, which failed to adequately capture the heightened risk of conditions like heart attacks in older individuals.
Dr. Simon Williams, an expert on heat-related health impacts at Swansea University, described the findings as highly significant. He noted that while younger adults may face UHS at 4C of warming above preindustrial levels, older adults are at risk of harmful and potentially fatal heat stress at just 1.5C. The study further estimates that each additional degree of global heating exposes approximately one million more people to at least 180 hours of UHS annually, with this burden falling disproportionately on the elderly.
Representatives from health and advocacy groups have expressed alarm at these conclusions. Caroline Abrahams, charity director at Age UK, stated that there is no longer any doubt that extreme heat is a direct health threat to the older population, noting that aging bodies struggle to adapt to temperature extremes and that heat can exacerbate existing medical conditions. Dr. Hilary Williams, clinical vice-president of the UK’s Royal College of Physicians, emphasized that extreme weather is a critical patient safety issue. She noted that hospitals frequently see surges in older patients suffering from dehydration, collapse, or the worsening of heart and kidney diseases during heatwaves. In one instance, a hospital doctor reported that temperatures on a geriatric ward reached 36C during recent extreme heat, which they described as an unsafe environment for both patients and staff.
Looking ahead, the researchers warned that if global heating continues to escalate, certain tropical and subtropical regions could become effectively uninhabitable, particularly for older individuals.
However, previous studies did not properly set out the different risks faced by younger people aged 15-39, middle-aged adults (40-59) and older adults (aged 60 or over). That is because they applied thresholds at which people cannot maintain their heat balance – which were accurate for younger people – to all age groups, and so overlooking older people’s greater risk of, for example, heart attacks.
“We know that heatwaves bring a surge in patients. Older people often arrive with dehydration, having collapsed, or with existing conditions like heart and kidney disease made worse by the heat. Managing multiple health conditions at once is hard enough but doing it when the body’s ability to regulate its own temperature is less efficient makes it harder still.”
