Why are older adults, children, and outdoor workers at higher risk during heatwaves?

Why do older adults suffer more during heatwaves?

Aging directly impairs the body's ability to cool itself. In a controlled experiment, healthy older adults (average age 70) showed significantly larger increases in core body temperature during simulated heatwaves compared to younger adults (average age 29), even when both groups did the same light activity and drank the same amount of water [5]. Their kidneys also struggled: after a hot, dry heatwave, older adults' kidney function (measured by eGFR) dropped by about 4%, while younger adults' kidney function actually improved [5]. This means older bodies simply cannot shed heat or protect vital organs as effectively.

Chronic diseases and medications add to the danger. A study in Slovenia found that during heatwaves, hospitalizations for endocrine diseases (like diabetes) among adults 75+ jumped by 23% to 48% in several years, even though overall hospitalizations didn't rise [3]. Many older adults take medications that affect fluid balance, heart function, or sweating, which can worsen heat stress. The same study noted that social isolation and a sedentary lifestyle further increase risk [3].

Heatwaves also harm mental health. In a large Mexican study of adults 60+, those who experienced more than two heatwaves in a summer had 15% higher odds of reporting high depressive symptoms [2]. The effect was strongest for people living in single-story homes with mixed floor materials and concrete roofs—suggesting that housing quality plays a big role in how heat affects well-being [2].

How do poverty and race make heatwaves deadlier?

Heatwaves don't affect everyone equally—they exploit existing inequalities. The largest study here, covering 73 million older U.S. adults over 18 years, found that an additional heatwave raised annual death rates by about 16.5 per 10,000 among Black individuals, compared to about 5.9 per 10,000 among White individuals—a nearly threefold difference [1]. The same study showed that people in high-poverty neighborhoods had a death increase of about 11 per 10,000, while those in neighborhoods with abundant green space actually saw a protective effect, with death rates dropping by about 13.5 per 10,000 [1]. This suggests that access to shade, parks, and well-insulated housing can literally save lives.

Housing quality is a key factor. In Mexico, older adults living in single-story homes with mixed floor materials and concrete roofs had significantly higher odds of depressive symptoms during heatwaves, while those in multi-story homes with wood floors and many rooms did not [2]. Poorer neighborhoods often lack air conditioning, have darker roofs that absorb heat, and are located in urban heat islands with less tree cover. These physical conditions compound the physiological vulnerabilities of aging.

What about outdoor workers and children?

Outdoor workers face a double burden: they are exposed to heat for longer periods and often lack knowledge about how to protect themselves. A survey of 356 outdoor workers in Nepal found that while 86% were aware of heat-related incidents, only 43% had even heard the term 'heatwave' [4]. Older workers (average age 37) actually had worse heat-protection practices than younger ones, and men had worse practices than women [4]. This gap between awareness and action is dangerous—the study found that better knowledge was linked to better protective behaviors, but many workers still didn't take basic steps like drinking enough water or taking breaks in the shade [4].

Children are also at higher risk, though the papers here focus less on them. Physiologically, children have a larger surface-area-to-body-mass ratio, which means they heat up faster in hot environments. They also sweat less efficiently and depend on adults to recognize and respond to heat stress. While the studies in this set primarily examine older adults, the same principles apply: anyone with a less mature or less efficient thermoregulatory system—whether due to age, illness, or medication—is more vulnerable. The global projections study notes that by 2050, over 23% of people aged 69+ will live in areas where daily maximum temperatures exceed 37.5°C, up from 14% today, exposing an additional 177–246 million older adults to dangerous heat [6]. This underscores that climate change will make these risks worse for all vulnerable groups.

About These Sources

This answer is built on 7 peer-reviewed studies — published from 2023 to 2026, 5 from 2024 or later, 6 in Q1 journals, collectively cited 114 times — selected as the most relevant from 11 studies that passed quality screening, drawn from 55 papers retrieved from a database of over 500 million.

Sources used in this answer

Related research questions