How to survive hell on earth

What is heat?

Heat refers to the subjective sensation of increased ambient temperature that many people find uncomfortable or stressful. Heat is often confused with warmth, but from a physical perspective they are different concepts. Heat describes the condition that is expressed by temperature. Warmth, by contrast, is a form of energy transferred due to a temperature difference between a system and its surroundings.

When the outside temperature rises and the body absorbs more heat than it can release through its natural cooling mechanisms, this can become problematic. Body temperature increases and the risk of heat stress grows. Especially at temperatures above 30 °C, many people in Central Europe have greater difficulty regulating their body temperature. Depending on health, age and acclimatisation to heat, this can pose health risks.

What happens in the body during heat?

When the body is exposed to high outside temperatures, it responds with various physiological mechanisms to keep core temperature stable. One of the first reactions is the dilation of blood vessels, which increases blood flow to the skin. This allows excess body heat to be released. However, this also means that blood pressure may drop, which can negatively affect physical performance.

Another important process is sweating. The body produces sweat to moisten the skin. As sweat evaporates, body heat is carried away and the body cools down. It is crucial to consume enough fluids and electrolytes, because the body loses important minerals during heavy sweating.

High humidity presents an additional challenge. When humidity is too high, sweat evaporation is hindered because the air is already saturated with water vapour. This impairs the cooling mechanism and means the body is less effectively cooled.

If the temperature rises above 40 degrees Celsius, the body is heavily stressed. At a body temperature of 42 °C this can become life-threatening, as body proteins are damaged and the organism may collapse. Therefore it is important that the body efficiently sheds excess heat to avoid these extreme temperatures.

Who is particularly vulnerable to heat?

At extremely high temperatures, people whose ability to self-regulate body temperature is limited or who belong to risk groups because of pre-existing conditions are particularly vulnerable. This includes older people, who often sweat less and feel thirst less strongly. People with chronic illnesses, especially cardiovascular disease, are also at risk because heat places an additional burden on the circulatory system.

In addition, infants, young children, people requiring care and people experiencing homelessness are particularly vulnerable, as they are generally less able to protect themselves from heat. Those who perform heavy physical work or spend long periods outdoors are also at greater risk because their body temperature rises faster.

Certain medications, such as diuretics or antidepressants, can also play a role because they reduce the body's cooling capacity. People without pre-existing conditions are not immune to heat stress either, especially if they exert themselves heavily, consume alcohol or take drugs. This can impair the body's ability to adapt.

Does extreme heat affect mental health?

It is proven that extreme heat has a negative impact on mental health. Studies show it increases the risk of psychological problems such as anxiety and depressive moods. Older adults, socially disadvantaged groups and people with existing mental health conditions are particularly vulnerable, as heat can worsen existing symptoms. Prolonged heat also raises the potential for aggression, which has been linked to a rise in violent behaviour.

Cognitive performance is also impaired by high temperatures. Another possible psychological effect is so-called climate anxiety, a state of inner tension and worry in response to the climate crisis. This feeling of helplessness can lead to increased release of stress hormones like cortisol. Over the long term this may promote depressive developments.

Large temperature swings can also worsen summer depression. This form of seasonal depression is less common than winter depression but is associated with, among other things, sleep disturbances, irritability and disrupted melatonin production.

What illnesses are caused by heat?

In extreme heat, various health problems of differing severity can occur with different symptoms. A common consequence is sunstroke, which occurs when the head is exposed to direct sunlight for too long without protection such as a cap or hat. Typical symptoms are headache, nausea, dizziness, fever and, in severe cases, impaired consciousness and seizures.

A more serious condition is heatstroke. It arises when the body's ability to regulate temperature via sweating is overwhelmed. This leads to a rapid rise in body temperature above 40 °C. Heatstroke can cause altered consciousness, loss of consciousness and brain swelling, and requires immediate medical attention.

A heat collapse is often caused by prolonged standing in intense heat and leads to a rapid drop in blood pressure. This can result in dizziness, weakness and in some cases loss of consciousness. People with heart or vascular disease or those taking diuretics are particularly at risk.

Heat cramps often occur after physical exertion in high temperatures. Excessive sweating causes the body to lose important electrolytes, which can lead to painful muscle cramps, especially in the legs, arms or abdomen.

Other heat-related conditions include heat rash, caused by blocked sweat glands and appearing as small itchy blisters, and miliaria, caused by blocked sebaceous glands. They occur mainly with tight or non-breathable clothing. Heat-related oedema, mainly affecting the lower legs, results from dilation of blood vessels and increased retention of water and salt in the body.

How to protect yourself from heat: practical tips

• During a heatwave, drink at least 2–3 litres of fluids daily. Cool but not ice-cold drinks such as water, herbal tea or diluted fruit juices are best. Avoid very cold drinks, as they can trigger more sweating and thus increase heat production.
• Reduce high-fat, hard-to-digest meals and opt for easily digestible foods such as salads, vegetables, water-rich fruit (e.g. melons, cucumbers) and whole-grain products. These foods help regulate fluid balance while providing vitamins and minerals.
• Wear loose, light-coloured clothing made of natural fibres like cotton or linen, which allow the skin to breathe and keep the body cool. Dark colours absorb more sunlight – avoid them in summer to prevent overheating. Protect your head and eyes with a wide-brimmed hat and sunglasses with UV protection.
• To keep indoor temperatures below 26°C, darken windows during the day and avoid heat sources such as ovens or electrical appliances. Ventilate in the morning and evening when it is cooler outside and use a fan to improve air circulation.
• Apply sunscreen with a high sun protection factor (at least SPF 30) regularly to all exposed skin to prevent sunburn and skin damage. Pay special attention to sensitive areas such as the face and neck.
• Prefer lukewarm showers rather than cold ones to open pores and allow body heat to escape. A cool foot bath or rinsing the wrists and neck with cold water can also provide quick relief.
• If you want to exercise, shift your training to the cooler hours of the day. Cycling, swimming or hiking are ideal because these activities are less taxing on the body at high temperatures.
• Monitor fluid balance if you have diabetes: drink regularly, especially in hot weather. Water or unsweetened teas are ideal, while sugary drinks and alcohol should be avoided. Store insulin correctly and check your blood sugar regularly.
• Walk on grassy surfaces or use tree-lined, shaded streets to reduce heat from surfaces. This protects your feet and helps prevent overheating.
• In summer months, heat waves and tropical nights due to climate change lead to significantly higher air temperatures, with daytime temperatures rising particularly strongly – heed heat warnings, seek shade to cool down and support your temperature regulation with regular breaks to avoid feeling unwell.
• If you or someone near you shows symptoms like dizziness, nausea or confusion, immediately seek shade, drink water and, if necessary, contact emergency services.

To meet the challenges of heat, it is essential to listen to your body and take preventive measures. With the right preparation we can better endure summer heat and protect our health.