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+--- Thread: What is the hottest temperature humans can survive? Redefining the limit (/thread-16355.html)
What is the hottest temperature humans can survive? Redefining the limit - C C - Aug 15, 2024
31 degrees Celsius is almost 88 degrees Fahrenheit
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(Aug 2024) What is the hottest temperature humans can survive? These labs are redefining the limit
https://www.nature.com/articles/d41586-024-02422-5
EXCERPTS: The models churned out a WBT of 35 °C as the limit of human survival. At that threshold, the body’s core temperature would rise uncontrollably. But the model treated the human body as an unclothed object that doesn’t sweat or move, making the result less applicable to the real world.
[...] Despite this, countless public-health bodies adopted it — even the Intergovernmental Panel on Climate Change — reducing the motivation to obtain a more relevant number, says Jay. “It’s a basic physical model with many limitations — but nearly everyone’s using this."
In a 2021 study, Kenney and his colleagues provided a better estimate: a WBT survival limit of around 31 °C. They calculated it by tracking the core body temperature of young, healthy people under different combinations of temperature and humidity while they were cycling.
“You do still see the 35 °C wet-bulb temperature tossed around, but people are starting to come around to the limit defined by Kenney’s lab,” says Robert Meade, a heat and health researcher at Harvard University in Cambridge, Massachusetts... (MORE - details)
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(Aug 2022) The temperature threshold the human body can’t survive
https://grist.org/climate/the-temperature-threshold-the-human-body-cant-survive/
INTRO: There’s a temperature threshold beyond which the human body simply can’t survive — one that some parts of the world are increasingly starting to cross. It’s a “wet bulb temperature” of 95 degrees Fahrenheit (35 degrees C).
To understand what that means, it helps to start with how the human body regulates its temperature. Our bodies need to stay right around 98.6 degrees F. If that number gets too high or too low, bad things can happen. And since bodies are always producing heat from normal functions, like digesting, thinking, and pumping blood, we need a place for that heat to go. That’s why our bodies have a built-in cooling system: sweat.
Sweat works by using a physics hack called evaporative cooling. It takes quite a bit of heat to turn water from a liquid to a gas. As droplets of sweat leave our skin, they pull a lot of heat away from our bodies. When the air is really dry, a little bit of sweat can cool us down a lot. Humid air, on the other hand, already contains a lot of water vapor, which makes it harder for sweat to evaporate. As a result, we can’t cool down as well.
This is where the term wet bulb temperature comes in: It’s a measure of heat and humidity, essentially the temperature we experience after sweat cools us off. We can measure the wet bulb temperature by sticking a damp little sleeve on the end of a thermometer and spinning it around. Water evaporates from the sleeve, cooling down the thermometer. If it’s humid, it hardly cools down at all, and if the air is dry, it cools down a lot. That final reading after the thermometer has cooled down is the wet bulb temperature.
In Death Valley, California, one of the hottest places on Earth, temperatures often get up to 120 degrees F — but the air is so dry that it actually only registers a wet body temperature of 77 degrees F. A humid state like Florida could reach that same wet bulb temperature on a muggy 86 degree day.
When the wet bulb temperature gets above 95 degrees F, our bodies lose their ability to cool down, and the consequences can be deadly. Until recently, scientists didn’t think we’d cross that threshold outside of doomsday climate change scenarios. But a 2020 study looking at detailed weather records around the world found we’ve already crossed the threshold at least 14 times in the last 40 years. So far, these hot, humid events have all been clustered in two regions: Pakistan and the Arabian Peninsula... (MORE - details)