Heat: The underestimated danger in the concrete jungle

When concrete surfaces glow and nights offer little cooling, the risk of circulatory problems, exhaustion, and serious illnesses increases rapidly. But those who support their bodies properly can better protect themselves even in record temperatures: Certain nutrients help maintain fluid and mineral balance, relieve stress on the circulatory system, and stay fit during the hot days.

01.07.2025, by URVI

Important NOTE

This article is for informational purposes only and does not replace professional medical advice. You should always discuss major lifestyle changes with a qualified medical professional first.

Why cities are particularly at risk

In cities, it is often significantly hotter in summer than in rural areas. This is due to the so-called urban heat island effect: concrete, asphalt, and other sealed surfaces store enormous amounts of solar energy during the day and release it only slowly at night. Thus, it remains hot in cities even after sunset, while rural areas are already cooling down. Sealed surfaces, in particular, can heat up to 50–60 °C or more – this is far above the ambient air temperature and places a massive strain on the body [1][2].

In addition, tall buildings and narrow urban canyons hinder air circulation, causing heat to build up in the city. Parks, trees, and green spaces that could provide cooling are often scarce. These factors make cities heat traps, where the risk of health problems is particularly high.

Another problem: the so-called "minimum mortality temperature" (MMT)—the temperature at which the mortality rate is lowest—vary by region. People in cool climates have adapted to lower temperatures, while in hotter countries the MMT is higher [3][4]. However, cities drive temperatures far beyond the local MMT, massively increasing the risk of heat-related deaths.

The underestimated danger: heat in the city

For many people, heat exposure not only affects existing health conditions, but also causes them to suffer from existing illnesses that are exacerbated by high temperatures. These include cardiovascular disease, kidney problems, respiratory diseases, or diabetes. Heat exposure rarely appears as a cause of death on death certificates, yet it contributes significantly to premature deaths.

A large study estimated that between 2000 and 2019, around 5 million people worldwide died annually from suboptimal temperatures – that is, 9.4% of all deaths [5]. In Europe, the 2003 heatwave dramatically demonstrated how deadly heat can be: In France alone, around 15,000 people died at that time [6].

Who is most at risk?

Older people over 65, children, chronically ill people, and pregnant women are particularly affected by the heat. But people who work outdoors or live in homes without adequate cooling are also at risk. With increasing climate change, heat is increasingly becoming a dominant health risk in European cities [7][8].

How much does heat shorten life and what are its consequences?

A 50-year analysis in Great Britain showed that most temperature-related deaths occurred in people who would have lived for at least six months without the heat exposure. Other studies suggest that many of these deaths reduce life expectancy by at least one year [4]. Temperature-related excess mortality is therefore not an inevitable fate – it is often preventable. At the same time, heat can cause severe fluctuations in blood pressure, thicken the blood, and strain the kidneys. It also increases the risk of strokes and thrombosis. Studies estimate that extreme temperatures cause 1.7 to 5 million premature deaths worldwide each year [4][5]. These figures show that heat is far more than just an annoying summer phenomenon – it is a serious health risk.

Life hacks for hot city weather

Drink enough


Water or unsweetened drinks are best. Alcohol and high-sugar drinks place additional strain on the circulatory system.

Create cool spaces


Keep shutters and curtains closed during the day and ventilate at night or early in the morning when it is cooler outside.

Adjust your diet

Prefer light food: Salads, fruit and vegetables put less strain on the metabolism than fatty or very protein-rich meals.

Cooling body zones

Rinse your wrists, neck, backs of your knees, or feet with cool water or apply cool compresses – these areas help cool down the entire body.

Wear light clothing & hats


Light, airy clothing reflects sun rays better than dark fabrics. Also, wear a hat to avoid sunstroke.

Use green spaces


Parks and shady places act like natural air conditioners and can lower the temperature locally by several degrees.

Promote long-term greening

Green roofs, facades, urban trees and green spaces are not “nice-to-have” extras, but urgently needed measures to keep cities habitable at all.

They act like natural air conditioners, lower the ambient temperature by several degrees, store rainwater, filter pollutants from the air and reduce particulate matter pollution.

The most important nutrients in hot weather
Nährstoffe bei Hitze
Nährstoff / Pflanzenstoff Wirkung bei Hitze
Elektrolyte (z. B. Natrium, Chlorid) Ersetzen durch Schweiß verlorene Mineralien und helfen, den Kreislauf stabil zu halten.
Kalium Reguliert den Wasserhaushalt und hilft, den Blutdruck zu stabilisieren.
Magnesium Stabilisiert den Kreislauf, reduziert Muskelkrämpfe und unterstützt den Flüssigkeitshaushalt.
Vitamin C Schützt vor oxidativem Stress durch Hitze und unterstützt die Nebennieren bei der Stressregulation.
Ashwagandha Hilft, die Cortisol-Ausschüttung zu regulieren und kann Stress durch Hitze abmildern.
Glycin Fördert erholsamen Schlaf und kann abends durch Gefäßerweiterung beim Abkühlen helfen.

Conclusion: Cities need green solutions and awareness

Urban heat is a serious and growing problem, exacerbated by climate change. Scientific studies show that heat shortens lives and worsens existing illnesses. But prevention, urban greenery, and proper behavior can help protect you and others. Cities must now focus on more greening and heat-adapted planning to remain livable in the future.

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Sources
  1. Oke, T.R. (1982). The energetic base of the urban heat island. Quarterly Journal of the Royal Meteorological Society, 108 (455), 1–24.
  2. World Meteorological Organization & WHO (2015). Heat waves and health: guidance on warning system development. WMO No. 1142.
  3. Hajat, S., et al. (2006). Impact of high temperatures on mortality: is there an added heat wave effect? Epidemiology, 17 (6), 632-638.
  4. Gasparrini, A., et al. (2015). Mortality risk attributable to high and low ambient temperature: a multicountry observational study. The Lancet, 386 (9991), 369-375.
  5. Zhao, Q., et al. (2021). Global, regional, and national burden of mortality associated with non-optimal ambient temperatures from 2000 to 2019: a three-stage modeling study. The Lancet Planetary Health, 5 (7), e415–e425.
  6. The Lancet. (2014). Heat-related deaths in Europe during the summer of 2003. The Lancet, 383 (9934), 1661.
  7. Popovic, M., et al. (2021). Heat and cold wave intensity and spatial extent on the Iberian Peninsula: future projections. Theoretical and Applied Climatology .
  8. Roca-Barceló, A., et al. (2024). Impact of population aging on future temperature-related mortality at different global warming levels. Nature Communications, 15 (1), Article 1796.
  9. Bannai, M., et al. (2012). The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Frontiers in Neurology, 3 , 61.