Heatwaves: A Growing Health Threat and How to Stay Safe

The World Health Organisation (WHO), alongside leading health and climate experts, warns that extended heatwaves are no longer a seasonal inconvenience but an escalating public health crisis. Rising global temperatures, driven by climate change, are setting new records year after year, raising urgent questions about the cumulative effectsof prolonged exposure to extreme heat.

The Hidden Dangers of Heatwaves

The immediate health impacts of extreme heat are well known: heatstroke, dehydration, and exhaustion. However, the real danger extends far beyond the visible symptoms. According to Agence France-Presse (AFP), prolonged heat can worsen chronic illnesses such as cardiovascular and respiratory diseases. These effects may not appear immediately — symptoms can develop, and even lead to death, days after a heatwave begins.

People should remain vigilant not only during heat events but also in the critical days following, when latent health impacts can surface.

Scientific research supports this caution. A 2011 Epidemiology study identified a “slight additional effect” of mortality risk after the fourth day of a heatwave. In contrast, a 2018 Science of the Total Environment study questioned the role of duration. However, newer findings from 2024, published in The Lancet Countdown and Sleep Medicine, present an emerging dimension: extreme heat disrupts sleep, impairing the body’s ability to recover and increasing vulnerability to illness.

Lessons from History

The dangers of prolonged heatwaves are not theoretical. The summer of 2003 in Europe serves as a stark reminder, when an extended heatwave claimed more than 70,000 lives. Since then, climate scientists have repeatedly warned that global warming will make such events more frequent, longer, and more intense. The health consequences are compounded by urban heat islands, air pollution, and aging populations, especially in densely populated cities.

Who Is Most at Risk?

While extreme heat affects everyone, certain groups are more vulnerable:

Older adults

Infants and young children

People with chronic illnesses (heart disease, asthma, diabetes)

Outdoor workers and athletes

Individuals without access to cooling or adequate shelter

For these populations, the combination of high temperatures and humidity can be life-threatening even over short exposure periods.

How to Protect Yourself and Prevent Heat-Related Illness

Stay Hydrated – Drink water regularly, even if you do not feel thirsty. Avoid alcohol and excessive caffeine.

Limit Outdoor Activity – Schedule errands and exercise for cooler times of the day, such as early morning or evening.

Create Cool Indoor Spaces – Use air conditioning or fans. If unavailable, seek out public cooling centres, libraries, or malls.

Wear Light Clothing – Loose, light-coloured fabrics help regulate body temperature.

Check on Vulnerable Individuals – Friends, family, and neighbours may need assistance during heatwaves.

Recognise Warning Signs – Symptoms such as dizziness, rapid heartbeat, confusion, or fainting require immediate medical attention.

The Path Ahead

Heatwaves will continue to intensify as climate change accelerates, making preparedness and prevention critical public health priorities. Governments, urban planners, and healthcare providers must collaborate to improve cooling infrastructure, emergency response, and public awareness campaigns.

While scientific debate continues over the precise cumulative effects, the evidence is clear: heatwaves can be deadly, and the risk is rising. Learning from past tragedies and taking proactive steps today could save thousands of lives in the future.