Scientists have identified the deadly heat and humidity levels for humans
Last reviewed: 07.06.2024
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Previously, scientists have reported that staying for six hours in conditions of 100% humidity and a temperature of +35°C can be fatal even for a healthy person. The new study found that such indicators may be lower. If at any point the sweating process is disrupted, it can lead to heat stroke, organ dysfunction and death, even at lower humidity and temperatures.
In this situation, the so-called wet bulb temperature is relevant. This is the lowest possible temperature to which moisture can be cooled by evaporation under constant pressure. At the same time there is an increase in absolute air humidity. Heat does not necessarily have to be extreme to lead to human death. At the same time, all people have an individual threshold of susceptibility, which depends on the age category, general health, other socio-economic factors. For example, over the past few years, fatalities have been reported en masse even at lower humidity levels and relatively less dangerous wet-bulb temperatures.
The findings allowed scientists to predict that a 2.5°C increase in global warming would push wet-bulb temperatures past the 35°C mark.
The theoretical limits of human survival are +35°C at 100% humidity, and +46°C at 50% humidity. To clarify these values, scientists from Pennsylvania State University used a special thermal chamber and a group of healthy young volunteers.
As a result, it was found that thermoregulatory capabilities reached their critical limit when the body lost the ability to prevent further increases in internal body temperature. This occurred at +30.6° on a "wet" thermometer. According to scientists' calculations, it would take five to seven hours for the fatal finale to occur under such conditions.
According to experts, children are most at risk of overheating, as their ability to regulate their own body temperature is still improving. The category of the most vulnerable people can also include the elderly, which is associated with less sweating activity. According to last year's statistics, more than 80% of deaths caused by hot conditions in European countries were among the elderly people who crossed the 65-year threshold. The risk group also includes people who have to stay outdoors for long periods of time in the heat, as well as those who do not drink enough water.
Scientists note that the increase in temperature on the "wet" thermometer is closely related to the increase in temperature indicators on the ocean surface. According to information from the European Union's Clinical Observatory, this year has seen a record high temperature of the world's oceans, which exceeded the previous record highs of 2016.
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