Scientists have calculated what air temperature in the heat can harm health
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Due to the extreme heat this summer, which broke the established records, scientists are trying to determine the air temperature that a person cannot withstand. Not only high temperature can be harmful, but also humidity, reports Science alert with reference to the study of the Virginia Climate Center. The combination of these factors is becoming more dangerous than previously thought, scientists say. The Limits of Human Adaptability In 2010, a study was published that theorized that temperatures of 35°C at 100 percent humidity and 46°C at 50 percent humidity are the upper safety limits below which the human body can no longer cool itself. That is, sweat will stop evaporating from the surface of the body to maintain a stable temperature inside. Only recently has this limit been tested in humans under laboratory conditions. Young, healthy men and women were brought to Knoll’s laboratory at Pennsylvania State University. These people were to experience heat stress in a controlled environment chamber. Photo: boscorelli/Depositphotos Experiments have shown which combinations of temperature and humidity start to become harmful even for the healthiest people. Each participant swallowed a small telemetry pill that continuously monitored their body temperature. They then sat in a chamber with the environment, moving just enough to simulate minimal activities of daily living, such as showering, cooking and eating. The researchers slowly increased either the temperature in the chamber or the humidity and observed when the subject’s core temperature began to rise. The combination of temperature and humidity at which the temperature inside a person begins to rise continuously is called the “critical environmental limit”. Below these limits, the body is able to maintain a relatively stable internal temperature for a long time. If the set limit of temperature and humidity is constantly increased, there is a risk of diseases. When the body overheats, the heart has to work harder, and when a person sweats, it reduces the volume of fluid in the body. In the most severe case, prolonged exposure to heat can lead to heat stroke. In this case, the person will need immediate and rapid cooling and medical treatment. Studies show that the upper environmental limit is even lower than the theoretical 35 °C. Overheating occurs at a temperature of approximately 31°C in various environments with relative humidity above 50%. Dry vs Wet Environment Current heat waves around the world exceed identified critical environmental limits and approach, if not exceed, even the theoretical limit of 35 °C at 100 percent humidity. In a hot, dry environment, almost all of the sweat produced by the body evaporates, which cools the body. However, there is a limit to the amount of sweat a person can produce, and people also gain more heat from higher air temperatures. Even lower temperatures and humidity can cause stress on the heart and other body systems. Heart rate begins to increase long before core temperature as we pump blood to the skin. And while exceeding these limits is not necessarily the worst-case scenario, long-term exposure can be tragic for vulnerable populations, such as the elderly and those with chronic illnesses. Scientists are now testing older men and women who are less resistant to heat. The elderly are also at risk due to an increased prevalence of heart disease, respiratory problems, and the use of certain medications. From 80% to 90% of heat victims are people over 65 years old. Read also: Almost 42°C heat: a temperature record was set in Rome
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