Heat Waves: Why Do Some People Die While Others Survive?

SadaNews - Every summer, heat waves recur, along with the usual warnings from health authorities to be cautious, drink water, and avoid going out during midday. However, this repeated warning often goes unnoticed by many, perhaps because most people consider the heat just a passing seasonal nuisance, not a real danger.

The truth is that some heat waves pass without any significant health impact, while others leave behind a toll of deaths. What is the difference between them? And what actually happens inside the body to reach such a point?

The World Meteorological Organization defines a heat wave as a period during which the daily maximum temperature exceeds the normal average for the region by at least 5 degrees Celsius for five consecutive days or more.

Temperatures are recording a noticeable gradual increase each year, along with a rise in deaths related to heat, which has prompted health organizations worldwide to launch awareness and education campaigns about the most important preventive tips and how to deal with the effects of heat waves, in an effort to reduce these increasing human losses.

The Most Affected Groups

Individuals with chronic diseases, such as diabetes, cardiovascular diseases, asthma, and mental health disorders, are considered the most vulnerable to the risk of death due to high temperatures. A sharp increase in heat wave victims has been recorded since 2000 to 2021, with an 85% increase in those over 65 years old.

Heat waves do not only affect the West; they hit the East just the same. Asian countries recorded about 45% of the total deaths between 2000 and 2019, amounting to 489,000, while the death rate in Europe was 36%.

On the other hand, young children and infants are among the most at risk for different physiological reasons than the dangers of heat for the elderly. A child's body absorbs heat from the surrounding environment at a relatively faster rate than an adult, due to the larger surface area of their skin compared to their body size, and they produce relatively more internal heat per kilogram of body weight.

Most importantly, the size of sweat glands in children is about 27% smaller than in adults, and the child's body starts sweating at a higher internal temperature than an adult, which delays the body's natural cooling response. Additionally, there's a purely behavioral factor; infants cannot express their feelings of thirst or request to be moved to a cooler place on their own, making them completely dependent on those around them to recognize the signs of danger.

Emergencies in Europe

The heat wave that struck Europe in June 2026 led to the closure of thousands of schools in France and Britain within a few days, after repeated fainting cases among students and unprecedented meteorological warnings.

The crisis revealed a striking gap in some countries, where there is a legal minimum temperature for winter periods, with no mandatory maximum limit in summer, leaving the closure decision to the discretion of each school.

The spectrum of those at risk of heat stress extends beyond this. On the health side, the risk increases for those suffering from high blood pressure or cholesterol, as well as people who are obese or overweight, or who are sedentary and inactive, along with pregnant women.

On the behavioral side, those relying on pain relievers or non-steroidal anti-inflammatory drugs are at greater risk, in addition to smokers, and those who overconsume caffeinated or sugary beverages instead of rehydrating with water, or who do not drink enough fluids at all, as well as drug or alcohol users.

In the work environment, workers who are subjected to ongoing psychological or professional stress, and those who avoid using personal protective equipment or limit breaks to go to the bathroom to avoid work interruptions, or who remain in wet clothing throughout working hours, double their chances of suffering from heat stress without always realizing it.

Why Do People Die from Heat?

Heat waves have become much more severe than they were 50 years ago, with felt temperatures on the hottest days of the year increasing by 4 to 5 degrees Celsius in some areas, especially in Europe, North Africa, and the Arabian Peninsula.

The felt temperature here is not just a number on the thermometer but an indicator that combines the actual heat and humidity levels. High humidity prevents the efficient evaporation of sweat, causing the body to feel hotter than the recorded actual temperature.

One of the reasons that explain the length and severity of some heat waves is what is known as the "heat dome" effect, a weather condition where hot air settles over a specific area for days or weeks without moving or dispersing, as occurred during the disastrous European heat wave in the summer of 2003.

This prolonged stability is what transforms heat from a passing annoyance into an accumulated health risk; each additional day under these conditions means more consumption of the body's recovery capacity, especially with the absence of any nighttime temperature drop that allows it to regain its balance.

Compounding the issue, nighttime temperatures are rising faster than daytime ones, which presents an additional health burden; continuous exposure to cumulative heat stress during extremely hot days limits the body's ability to shed this heat and recover from its effects at night, increasing fatigue and tiredness, thereby elevating the risk of mortality.

The body responds to high temperatures by trying to mitigate their impact, with symptoms gradually appearing in what is medically known as heat stress. It begins with dehydration and excessive sweating, followed by fatigue, exhaustion, headache, reduced urine output with a change in its color, muscle cramps, skin changes such as rashes, drying, itching, and tingling, in addition to nosebleeds and feelings of nausea.

At this stage, heat stress is treatable at home if the person can reduce their temperature within 30 minutes by moving to a cool place and drinking fluids. However, if exposure to the heat continues without intervention, heat stress can develop into a far more serious condition known as heat stroke, which is a medical emergency requiring immediate intervention.

The crucial distinguishing sign between the two conditions is the appearance of neurological symptoms. While the person in heat stress remains aware and capable of speaking clearly, heat stroke causes confusion, incoherent speech, loss of balance, and may lead to complete unconsciousness. This change in mental state is the signal that should prompt those around the affected individual to call for emergency assistance immediately without delay.

With continuous exposure to heat alongside hard work and without compensating for lost fluids, health issues can escalate and become permanent damages; in terms of the kidneys, the risk of chronic kidney disease, reduced function, and stone formation increases.

On the cardiovascular and respiratory fronts, the chances of developing heart disorders such as cardiac stress, high blood pressure, or rapid heartbeat increase, alongside respiratory issues like asthma and difficulty breathing. Prolonged high heat is also associated with increased risks of liver diseases, skin cancer, and diabetes.

How Does Death Occur Due to Heat?

Continuous heat waves that last for days and nights lead to a series of physical changes that weaken and exhaust the body, with their serious impact focused on the heart and circulatory system.

As large amounts of fluids and salts are lost through sweating, blood becomes thicker and more concentrated, increasing the likelihood of clots forming in the arteries that supply blood to the heart and brain; this explains the higher incidence of strokes and heart attacks during heat waves.

Simultaneously, the body responds to extreme heat by dilating blood vessels in the skin and increasing blood flow to it in an effort to cool down and shed excess internal heat. This requires pumping more blood than the heart may be able to handle if it is already weak or ill, rapidly deteriorating its performance due to the increased load, leading to heart failure and potentially death.

How Can We Avoid the Health Risks Posed by Extreme Heat?

Health organizations and specialized agencies recommend following various preventive measures to avert the severe consequences of extreme heat, which can be grave. These measures are not merely theoretical suggestions; they have proven effective in real experiments around the world.

After implementing a preventive action plan in France in 2006, 4,388 fewer deaths were recorded than expected based on historical trends for that period.

In Italy, the proportion of heat-related deaths fell from 6.3% before the implementation of the early warning plan (1999-2002) to 4.1% after its implementation (2013-2016).

In India, an estimated 2,380 deaths were avoided after implementing an early warning system in Ahmedabad, with a significant decrease in the relative risk of death at extreme heat levels post-intervention compared to pre-intervention.

These results confirm that investing in early warnings and awareness is not just a precautionary measure but a proven effective tool to reduce human losses.

On the health policy level, activating and generalizing early warning systems to predict heat waves before they occur is a top priority, alongside disseminating recommended health instructions through various media, and training health personnel to manage and diagnose heat stress cases early, with precise coordination between health authorities and emergency medical teams during periods of heat waves.

On an individual level, it is advisable to avoid going out or performing any strenuous outdoor activities during the peak heat hours, attempting to stay in the shade, as temperatures there are 10 to 15 degrees Celsius lower than those exposed to the sun.

At home, keeping it as cool as possible by opening windows at night when temperatures drop, minimizing the operation of electrical appliances to reduce internal heat sources, and closing and covering windows with dark curtains to block sunlight during the day is recommended.

It is also preferable to set the air conditioning at 27 degrees Celsius while running the fan in the room, as this can lower the room temperature by an additional 4 degrees.

On a personal level, taking cold showers, keeping clothes damp while wearing them, and drinking plenty of water regularly without waiting to feel thirsty is advised.

Educational programs that inform people about the dangers of heat waves and preventive measures remain the cornerstone of any effective long-term preventive strategy.

Source: Al Jazeera