Maximum heat limit for human body identified
Scientists have identified the maximum mix of heat and humidity a human body can survive.
Even a healthy young person will die after enduring six hours of 35-degree Celsius (95 Fahrenheit) warmth when coupled with 100 percent humidity, but new research shows that threshold could be significantly lower, according to Science Alert.
At this point sweat – the body’s main tool for bringing down its core temperature – no longer evaporates off the skin, eventually leading to heatstroke, organ failure and death.
This critical limit, which occurs at 35 degrees of what is known as “wet bulb temperature,” has only been breached around a dozen times, mostly in South Asia and the Persian Gulf, as per Colin Raymond of NASA’s Jet Propulsion Laboratory.
None of those instances lasted more than two hours, meaning there have never been any “mass mortality events” linked to this limit of human survival, said Raymond, who led a major study on the subject.
But extreme heat does not need to be anywhere near that level to kill people, and everyone has a different threshold depending on their age, health and other social and economic factors, experts say. For example, more than 61,000 people are estimated to have died due to the heat last summer in Europe, where there is rarely enough humidity to create dangerous wet bulb temperatures.
But as global temperatures rise – last month was confirmed on Tuesday as the hottest in recorded history – scientists warn that dangerous wet bulb events will also become more common.