Why Are Heat-Related Deaths Surging Across the Globe?

Heat-related deaths and illnesses have risen sharply in recent decades and are projected to increase if urgent action is not taken. The UK Health Security Agency data suggests the UK was estimated to have around 2985 heat-related deaths. In addition to this, it has been revealed that 11,000 Americans have died from heat-related deaths since 1979. Europe saw an estimated 61,672 heat-related deaths during the summer of 2022, with Italy, Germany, France, Spain, the UK and Greece recording the highest heat-related mortality rates. Also, the studies show that vulnerable people, such as adults aged 65 and older and infants under one year, are at higher risk.

What Causes Heat-Related Deaths?

Heat-related deaths can occur through various means related to the environment. They have a wide-ranging effect across the planet and are not exclusive to any one specific area.

Heatwaves

Heatwaves are prolonged periods of excessively hot weather and are among the most dangerous of natural hazards. The World Health Organization (WHO) indicates that “heatwaves rarely receive adequate attention because their death tolls and destruction are not always immediately obvious”. According to the WHO, 166,000 people died from heatwave effects from 1998-2017, and about 70,000 people died during the 2003 heatwave in Europe.

Other effects caused by heatwaves include:

• Wildfires.
• Water Shortages.
• Agricultural Damage.
• Heat-Related Illnesses (Heat Stroke, Heat Exhaustion and Sunstroke etc.).

The human population is constantly being exposed to extreme temperature events that increase in frequency, duration, and magnitude. About 125 million people were exposed to heatwaves between 2000 and 2016 globally, according to the WHO.

Heatwaves are also becoming increasingly intense due to climate change. Additionally, warmer temperatures recorded at night time can be hazardous because the human body may not be able to recover from the excess heat absorbed during the day. High humidity can impede sweating, affecting the body's ability to regulate its temperature effectively.

Urban Heat Island Effect

The urban heat island (UHI) effect occurs when urban areas experience significantly higher temperatures than the surrounding rural areas. Analysis from Iberdrola suggests that “average annual air temperature in a city with 1.5 million plus inhabitants can be between 1 - 3 °C higher during the day concerning its surrounding area, while at night that difference can be even greater, even by up to 10 °C.”

There are several known causes of the UHI effect. Firstly, structures such as concrete and buildings have materials that absorb and re-emit more heat than natural surfaces like vegetation and water bodies that are likely found in rural areas. Secondly, the less vegetation likely in urban areas reduces the potential of evapotranspiration cooling effect occurring. Evapotranspiration refers to the total water loss from a land surface to the atmosphere. It encompasses the water vapour that evaporates from the soil surface and liquid water on plant surfaces, as well as the water transpired from within plant tissues.

Finally, the combination of tall buildings and narrow streets in urban areas causes an "urban canyon effect" that traps heat in pockets and creates extremely high temperatures. Fourthly, the high population in cities means that more heat is generated from vehicles, air conditioning systems, factories, and other sources that add to the excessive heat that causes the urban heat island effect. As a result, the UHI effect can cause high energy demand for cooling even in predominantly cold climates like the UK, increase pollution to the air, cause climate change impacts, and cause heat-related deaths.

Vulnerability of the Population

Certain community members are more likely to suffer from heat-related illnesses. For example, elderly individuals may be less able to regulate their body temperature due to ageing. Naturally, children, due to their small body surface area, may be more susceptible to heat waves, and prolonged exposure to heat waves by outdoor workers poses significant risks.

People with Pre-Existing Health Conditions

People with chronic illnesses, respiratory diseases, cardiovascular disease and other factors such as dehydration and certain types of medication effects have increased vulnerability to heat-related illnesses and mortality.

How to Prevent Heat-Related Deaths

Research by Luthi et al. “highlights the urgent need for strong mitigation and adaptation to reduce heat waves impacts on human lives”. Vulnerable people such as elderly individuals and children must not be exposed to prolonged periods of high temperatures. Health professionals must receive adequate training and support to work with vulnerable groups in the community. The strategies to mitigate the UHI effect include improving urban vegetation and greenery, using materials with suitable design characteristics, and improving urban design through architects and structural and civil engineers.

The urban heat island effect is a significant issue that society must mitigate against, such as the impact of heat-related illness, mortality, and climate change.

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