When does heat become dangerous for people?
A hot day and a tropical night refer to extreme temperatures in the context of weather. A hot day is a day with high temperatures, often above 30 degrees Celsius. A tropical night, on the other hand, refers to high temperatures and high humidity levels during the night, making it difficult for the body to cool down, even when the sun is not shining.
July brings the summer heat to Germany. Due to the hot air from North Africa, almost the entire Federal Republic will reach the 30-degree mark on this Tuesday - perfect bathing weather. However, hot days and tropical nights are a serious health concern for scientists. The body can adapt to some extent, but it is much more difficult for children, sick and elderly people than for healthy adults.
When does heat become dangerous for people?
A rule of thumb is that heat becomes dangerous when the body absorbs more heat than it can release. When the body temperature gets out of control and rises rapidly, it can lead to various health issues. This threshold is highly individual and depends on age, health condition, activity level, and acclimatization. At temperatures above 30 degrees, many people in Central Europe experience more stress trying to cool down than at lower temperatures. Acclimatization to high temperatures usually takes several days.
Why can heat be fatal in extreme cases?
Heat is a significant stressor for the human body. The organism works hard to maintain its temperature around 37 degrees Celsius. Most cells, enzymes, proteins, and the immune system function optimally under these conditions. However, extreme temperature fluctuations can disrupt these processes. When the human body temperature exceeds 42 degrees Celsius or drops below 32 degrees Celsius, it can be fatal.
How does the body's climate control system work?
To prevent organ damage, the body increases its cooling efforts during heat and releases fluids and salts - sweat. Sweat cools the skin through evaporation. High humidity slows down this process, making sweating less effective in humid weather. If the body is warmer than its surroundings, it can also radiate heat - like a glowing bulb warms up its surroundings. During extreme heat, blood vessels expand, causing a decrease in blood pressure. The heart increases its pumping capacity, and breathing can become faster. Brain performance can decrease due to reduced oxygen supply.
What is a heatwave?
For the German Weather Service (DWD), a heatwave is an extreme event that can harm human health, ecosystems, and infrastructure. Internationally, there is no uniform definition of the term. The Weather Service defines a heatwave as a prolonged period of unusually high thermal stress. Parameters include not only air temperature but also humidity (humidity), solar radiation from the sun, earth, and atmosphere, and wind. In our latitudes, heatwaves often occur in conjunction with persistent summer high-pressure systems.
What do "Hot Day" and "Tropical Night" mean?
A hot day is a day with high temperatures, often above 30 degrees Celsius. A tropical night, on the other hand, refers to high temperatures and high humidity levels during the night, making it difficult for the body to cool down, even when the sun is not shining.
The air temperature reaches 30 degrees or more on so-called Hot Days. In Germany, for example, there were 17 such Hot Days in 2022, with up to 20 being recorded in previous years. In a Tropical Night, the thermometer does not drop below 20 degrees. For the Federal Environment Agency, Heat Waves are periods during which Hot Days and Tropical Nights alternate over a longer period. This combination is considered extremely problematic for health, as people are not only exposed to extreme heat during the day, but their bodies also cannot recover sufficiently at night due to a lack of cooling.
When was the last notable Heat Wave in Germany?
The German Weather Service mentions the year 2003 as an example of a very notable wave. At the beginning of August that year, there were eleven consecutive days with temperatures above 35 degrees in Southern Germany. This "Century Summer" with an average temperature of 19.7 degrees ranks first in the statistics since 1881. According to DWD data, the summers of 2018 (19.3 degrees), 2019 (19.2), and 2022 (19.2 degrees) are also considered unusually warm. Metrologists consider higher summer temperatures to be "soon typical" in times of climate change.
What were the consequences?
The heat waves of the German summer of 2003, according to the German Weather Service, are estimated to have caused around 7600 additional deaths in Germany. For researchers at the Robert Koch Institute, the unusually high summer temperatures in recent years have led to statistically significant numbers of deaths several times. There were approximately 8300 heat-related deaths in 2018, 6900 in 2019, 3600 in 2020, and 4500 in 2022. In the past 30 years, there has been a certain adaptation to higher temperatures, but heat events remain a significant threat to the health of the population in Germany.
Who is particularly at risk?
High outdoor temperatures can put a lot of strain on the heart-circulatory system. People with chronic conditions in this area should therefore be particularly careful. With increasing age, the body's temperature regulation slows down, and there are fewer sweat glands. Older people also seldom feel thirsty. Even a loss of just one to two percent of body water, according to the Malteser Aid Service, can lead to headaches, fatigue, concentration disorders, and dizziness. In children, sweating production is lower.
Babies and small children therefore suffer from heat-related ailments more quickly - the risk here is also dehydration. People who work heavily in the open air are also at risk in the heat. So are people who have difficulty helping themselves, such as the elderly, mentally ill, drug addicts, and homeless people.
What are typical heat-related ailments?
Heat cramps, heat exhaustion, and heat stroke are typical heat-related ailments. Heat cramps are caused by heavy physical exertion in the heat and result in painful muscle cramps, often in the legs. Heat exhaustion is characterized by symptoms such as dizziness, fatigue, headache, and nausea. Heat stroke is a life-threatening condition that can lead to organ failure and even death if not treated promptly. It is characterized by symptoms such as confusion, loss of consciousness, and a body temperature above 104 degrees Fahrenheit.
Heat-related ailments can be prevented by staying hydrated, wearing light, loose clothing, and avoiding prolonged exposure to the sun during the hottest hours of the day. People at higher risk, such as the elderly and children, should be monitored closely during heat waves.
- Sunstroke: If the head is exposed directly to the sun for too long without a hat, cap, or cloth, it can lead to irritation of the brain membranes. In severe cases, there is brain swelling. Symptoms may include headaches, nausea and vomiting, fever, sometimes consciousness disturbances, and seizures.
- Heatstroke: When the body's sweating capacity is reached, there is a heat build-up: The body temperature rises quickly - often within 10 to 15 minutes - to over 40 degrees or more. As a result, the brain swells and there are headaches, consciousness changes, or unconsciousness. This is a case for the emergency services.
- Heat collapse: Due to intense heat, there is a decrease in blood pressure. The result is reduced brain perfusion, which can lead from weakness and nausea and dizziness to unconsciousness. Also an emergency.
- Heat cramps: When someone is physically exerting themselves in the heat, for example during sports or gardening, they usually sweat profusely. As a result, there can be a lack of fluid and electrolytes such as sodium or potassium in the body. They help control nerve and muscle function. The muscles react to an electrolyte deficiency with cramps or muscle pain.
- Heat exhaustion: If sweat cannot evaporate sufficiently due to little breathing activity or tight clothing, the sweat glands become blocked. The result are small, often itchy or burning blisters.
The concerns about hot days and tropical nights extend to the broader context of climate change and global warming. Health experts warn that prolonged exposure to high temperatures can exacerbate existing health issues, particularly for children, the elderly, and those with pre-existing conditions. In fact, heat waves, defined as prolonged periods of unusually high thermal stress, have been linked to significant increases in heat-related deaths in recent years.
To mitigate these health risks, education and awareness about heat-related ailments, such as heat cramps, heat exhaustion, and heatstroke, is crucial. Knowledge about preventative measures, including staying hydrated, wearing light clothing, and avoiding prolonged sun exposure, can help individuals protect themselves during heatwaves. Additionally, specific groups, such as the elderly and children, require extra care and close monitoring during these extreme weather events.
