Older Adults Face Greater Heat Risk Than Previously Thought, Lancet Study Finds

Older adults could face serious health risks from extreme heat at lower temperatures than previously estimated, according to a new study published in The Lancet Public Health. The research examined how age affects the body’s ability to cope with heat and found that older people may reach dangerous heat-stress conditions sooner than younger adults.

The findings are particularly important for countries such as India, where rising temperatures and a large population could increase exposure to dangerous heat. Researchers warn that conventional heat-risk assessments may underestimate the threat to older people because they do not always account for differences in how the body responds to heat at different ages.

The human body normally keeps its temperature within a safe range by sweating and increasing blood flow to the skin. Ageing can weaken these responses. Older adults generally sweat less efficiently, while their cardiovascular system may face greater strain during periods of extreme heat. This can make it harder for the body to release excess heat.

The study focuses on what researchers call uncompensable heat stress, a condition in which the body can no longer lose enough heat to maintain thermal balance. Once this happens, prolonged exposure can lead to serious health problems, including heat exhaustion, heatstroke and potentially death.

One of the study’s key findings is the scale of future exposure. At 3°C of global warming, more than half of India’s population and over 80% of its older adults could experience at least 180 hours of intolerable heat stress each year, according to the study’s projections.

The risk is not limited to one part of India. Previous research published in AGU Advances has also found that uncompensable heat stress is already increasing across India and could spread significantly during the monsoon season as temperatures and humidity rise. Under 2°C of global warming, the study projected that monsoon-season heat stress could affect around 53% of the country, compared with about 60% during summer.

This has important implications for public health planning. Heat-health warnings are often based mainly on temperature forecasts, but the new research suggests that age and human physiology also need to be considered when assessing risk.

For older people, the danger can be greater if they have existing health conditions or take medicines that affect sweating, blood pressure or fluid balance. Access to cooling, shade, drinking water and timely medical care can therefore become increasingly important during extreme heat.

The findings also have implications beyond healthcare. Older people may need greater protection in homes, workplaces and public spaces as heat exposure increases. Cities may need more shaded areas, cooling centres, better ventilation and heat-response plans designed specifically for vulnerable populations.

India’s ageing population makes the issue even more important. As the number of older adults increases alongside rising temperatures, more people could face periods when their bodies struggle to cope with extreme heat.

The broader message from the research is clear: heat risk cannot be measured by temperature alone. Age, humidity, health, activity levels and access to cooling can all affect how dangerous extreme heat becomes.

For India’s healthcare and public-health systems, this means preparing not only for hotter days, but also for a population that could become increasingly vulnerable to them.