On a sweltering afternoon in Madrid last July, a man stood in a public fountain, his face lifted toward the spray of cool water—a moment of relief that represents something far graver than summer discomfort. Over the last four years, more than 200,000 people across Europe died from heat-related causes, and according to the World Health Organization's Europe office, most of those deaths were preventable.
Heat waves are no longer the occasional anomaly of summer—they are now a recurring crisis that strains health systems and infrastructure across the continent. As meteorologists announced this week that El Niño has formed in the Pacific and is expected to reach historic strength, experts warn that this natural warming cycle, layered on top of climate change driven by fossil fuel pollution, will likely intensify extreme weather worldwide. The stakes are higher than ever, and the WHO is sounding an urgent alarm.
"The impacts of climate change are a clear and present danger, and its most immediate and lethal manifestation is extreme heat," said Dr. Hans Kluge, director of the WHO's Europe office. His office has called for an ambitious and specific response: implementing heat action plans that include everything from opening cooling centers to introducing flexible work schedules and midday breaks that keep workers out of the most dangerous hours of the sun.
The science behind heat illness is straightforward but deadly. Heat exhaustion and heat stroke can develop rapidly and silently, especially among vulnerable populations. Children, the elderly, people living alone, and those with heart, lung, or kidney conditions face disproportionate risk. Urban and rural poor communities suffer most acutely because of low-quality housing and limited access to air conditioning—a disparity that turns a natural phenomenon into a public health inequality.
The WHO's prevention guidance is practical and grounded in evidence. Stay inside during the hottest hours of the day, ideally spending two to three hours in a cool place. If you must go outside at midday, avoid strenuous activity and seek shade. At home, close windows and cover them during the day; open them after dark when outdoor temperatures drop. Set air conditioners to 81 degrees Fahrenheit and use fans to circulate air. Hydration matters enormously—drink about one cup of water per hour—and wear loose, lightweight clothing that lets sweat evaporate. A wide-brimmed hat, sunglasses, and sunscreen are simple but effective defenses.
For those caring for others, vigilance is critical. Never leave children or animals in parked vehicles, where temperatures can skyrocket within minutes. If you're pushing a stroller in extreme heat, use a thin, wet cloth to cover it—dry fabric traps heat dangerously. Check regularly on older relatives and neighbors, especially those who live alone.
Manual and outdoor workers face particular peril when their schedules offer no flexibility to escape the midday heat. This is where institutional change becomes as important as individual action. Cooling centers, modified work hours, and paid breaks during extreme heat events can be lifesaving measures.
Dr. Kluge's stated goal is unambiguous: "zero heat-related deaths." It is audacious but not impossible. With heat waves now a permanent feature of the European summer, what was once framed as personal precaution has become a matter of collective responsibility and systemic change.