Introduction
Every summer, thousands of people around the world are hospitalized with heat-related illness, many of them unaware of how serious their condition had become until it was too late. Heat stroke does not announce itself with obvious warning signals. It strikes fast, escalates rapidly, and without immediate intervention, it can cause permanent organ damage or death.
The negative health impacts of heat are predictable and largely preventable with specific public health and multi-sectoral policies and interventions. Yet heat-related illness remains one of the most underestimated public health emergencies of the summer months. This blog covers everything you need to know — what heat stroke is, who is most at risk, how to prevent it, and what to do in an emergency.
What Is Heat Stroke and Why Is It So Dangerous?
Heat stroke is a life-threatening medical emergency that occurs when the body’s internal temperature rises to 40°C (104°F) or higher. This condition often results from prolonged exposure to high temperatures, especially when combined with physical exertion, such as working or exercising outdoors in extreme heat. Unlike milder heat-related illnesses like heat exhaustion or dehydration, heat stroke is far more serious and can cause lasting damage to vital organs, including the brain, heart, kidneys, and muscles.
When the body’s natural cooling mechanism fails, blood flow shifts away from vital organs and the brain begins to swell all within minutes. Heat stroke causes multi-organ failure in 30% of cases, and delayed diagnosis of more than six hours increases mortality by 40%.
Heat Exhaustion vs. Heat Stroke: Know the Difference
Most people confuse the two — and that confusion costs lives.
Heat Exhaustion — The Warning Stage
The person is still sweating, conscious, and body temperature remains below 40°C. Symptoms include heavy sweating, weakness, nausea, dizziness, and cool, pale, clammy skin.
Heat Stroke — The Medical Emergency
The body has already lost control of its temperature regulation. Key signs include:
- Body temperature above 40°C
- Hot, dry, or red skin with no sweating
- Rapid and strong pulse
- Confusion, slurred speech, or seizures
- Loss of consciousness
The Scale of the Problem
The data makes the urgency clear. In 2022, the Global Burden of Disease Study estimated 24,500 heat stroke-related deaths worldwide, and heat stroke accounts for approximately 12% of all weather-related deaths globally.
There was a 74% increase in heat-related deaths between 1980 and 2016, and in 2019, more than 356,000 people in nine countries died from extreme heat-related causes. Between 2000 and 2021, heat-related mortality from all causes in people older than 65 years increased by approximately 85%. These are not distant statistics — they reflect a growing and accelerating public health crisis directly linked to rising global temperatures.
Who Is Most at Risk?
Vulnerability to heat is shaped by both physiological factors, such as age and health status, and exposure factors such as occupation and socio-economic conditions. Specifically, the highest-risk groups include:
- Older Adults: Elderly individuals aged 65 and above account for 60% of heat stroke deaths. Their bodies adapt to heat more slowly, and they may not feel thirst as strongly as younger adults.
- Young Children: Infants under one year of age have a three times higher heat stroke risk than children aged one to four. They depend entirely on caregivers to recognize and respond to heat danger.
- Outdoor and Manual Workers: Outdoor and manual workers, athletes, and civil protection employees are exposed to excess heat because of their work and are susceptible to exertional heat stress.
- People with Chronic Illness: Obesity is associated with a 40% higher risk of heat stroke, and conditions such as heart disease and diabetes further increase vulnerability.
- Urban Populations: Urban and rural poor are often disproportionately exposed to overheating due to low-quality housing and lack of access to cooling.
Respect Peak Heat Hours
Limit outdoor activity between 10 AM and 4 PM when solar radiation and ambient temperatures are at their highest. Plan errands, exercise, and outdoor work for early morning or evening hours.
Dress Appropriately
Wear loose, light-coloured, breathable fabrics such as cotton or linen. Dark, tight clothing traps heat against the body and significantly slows natural cooling.
Never Leave Anyone in a Parked Car
A vehicle’s interior can reach dangerous temperatures within minutes — even on mild days with windows partially open. Never leave a child, elderly person, or pet inside a parked car under any circumstances.
Acclimatize Gradually
Regular heat acclimatization through 10 to 14 days of gradual heat exposure reduces heat stroke risk by 30% in outdoor workers. Sudden exposure to extreme heat after time spent in air-conditioned environments significantly increases risk.
Check on Vulnerable People
During extreme heat events, a phone call or brief visit to elderly neighbours, relatives, or those living alone can be lifesaving.
Emergency Response: What to Do Right Now
If someone is showing signs of heat stroke, act immediately:
- Call emergency services without delay
- Move the person to a cool, shaded area
- Remove excess clothing
- Apply ice packs to the neck, armpits, and groin
- Fan the person while misting with cool water
- If conscious and able to swallow, offer small sips of cool water
- Do not leave the person alone
Immediate cooling, reducing body temperature to 38–39°C within 30 minutes, reduces mortality by 50%. Time is the most critical factor.
References
- World Health Organization (WHO).Heat and Health. WHO Fact Sheet. Available at: https://www.who.int/news-room/fact-sheets/detail/climate-change-heat-and-health
- Centersfor Disease Control and Prevention (CDC). Extreme Heat and Health. Available at: https://www.cdc.gov/extrem
