The Silent Killer: Why Heat Deaths Happen at Home

When most people think of heat deaths, they imagine construction workers collapsing on job sites or athletes succumbing during marathons. The reality is far more mundane—and more widespread.

The vast majority of heat deaths happen in homes and hospitals, where people with existing health conditions are quietly pushed beyond their physiological limits. Heat is rarely mentioned on death certificates, making this threat particularly invisible to policymakers and the public.

Dr. Madeleine Thomson, who leads climate impacts work at Wellcome, explains that extreme heat doesn’t just kill. “It also increases the risk of heart disease, pregnancy complications, and poor mental health,” she notes.

Last summer’s European heatwave claimed 24,400 lives across major cities, with 85% of deaths occurring among people over 65. Britain’s 2022 summer saw an estimated 2,800 extra deaths among elderly residents from heat-related causes.

Nighttime temperatures are critical for recovery. When temperatures don’t drop below 20°C—so-called tropical nights—bodies can’t recover from daytime heat stress. Southern Europe experienced a record 23 such nights last summer, nearly triple the historical average.

Children warm up faster due to their smaller body size, while pregnant women struggle with temperature regulation. Both groups face heightened vulnerability during heatwaves, yet heat action plans often overlook these populations.

Cities face an additional challenge: the urban heat island effect makes them significantly hotter than surrounding areas. Buildings and pavement absorb and trap heat, creating dangerous conditions that persist long after sunset.

Simple interventions save lives: early warning systems, cooling centers, targeted support for vulnerable groups, and restrictions on outdoor work during peak heat. The question is whether cities will implement these measures before the next record-breaking heatwave arrives.