In the context of , which is causing global temperatures to rise, extreme is becoming increasingly common. Consequently, there is a serious threat to human health. Our bodies are resilient, but their limits are not infinite.
According to a study published in the journal Science Advances, a person can withstand a wet bulb temperature of 35 °C. However, the wet bulb temperature is not the same as the air temperature reported by meteorologists. It is measured using a thermometer wrapped in a cloth soaked in water. This measurement takes into account both temperature and humidity. This is crucial because, in high humidity, sweat evaporates more slowly from the skin, making it harder for the body to cool down.
If humidity is low and temperature is high, or vice versa, the is unlikely to be critical for the human body, according to Colin Raymond, a researcher at NASA’s Jet Propulsion Laboratory who studies extreme heat. But when both humidity and temperature are very high, the wet bulb temperature can approach dangerous levels.
For example, at an air temperature of 46.1 °C with 30% humidity, the wet bulb temperature would reach 30.5 °C. However, at an air temperature of 38.9 °C with 77% humidity, the wet bulb temperature would be 35 °C—dangerous for human health.
The reason people cannot survive extreme heat and humidity is that they are unable to regulate their internal temperature. “If the wet bulb temperature exceeds body temperature, a person can still sweat, but they won’t be able to cool their body down to the temperature necessary for physiological functioning,” Raymond explained in an interview with Live Science.
Under such conditions, the body becomes hyperthermic and suffers from . According to the Cleveland Clinic, this can lead to rapid heartbeat, confusion, fainting, and even coma.
However, a wet bulb temperature of 35 °C will not result in immediate death. It takes about three hours for such a temperature to be lethal, says Raymond. He notes that it is actually impossible to determine the exact time required for this. Some researchers have attempted to answer this question but were unable to do so ethically, as it would be irresponsible to expose participants to such high temperatures.
Extreme Heat – A “Multiplier of Disease”
According to Raymond, air conditioning can provide relief from unbearable heat, but not everyone has access to it. Even in areas where many people have air conditioning, the power grid can be unreliable. Meanwhile, with global warming, is becoming more frequent and lasting longer.
Paul Mosley, a researcher at Arizona State University studying heat-related illnesses, noted that 35 °C on the wet bulb thermometer is the maximum temperature a person can withstand under optimal conditions. In reality, factors such as age, physical fitness, certain medications, and health status can limit a person’s ability to tolerate heat even at lower wet bulb temperatures. High temperatures cause numerous health issues, including elevated blood pressure, exacerbation of heart diseases, kidney problems, as well as diabetes, asthma, and dementia.
This is why Mosley refers to heat as a “multiplier of disease.” Thus, the real impact of heat is far more serious than many people realize.
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