With the the influence of climate change, temperatures around the world are rising so fast, and the heat is becoming very bad for humans an increasing threat to health. Although our bodies are very resilient, you must consider they also have their limitations.
When and where is the final temperature in nature that the human body can withstand at all?
According to the study, the answer is short and clear – 35 degrees Celsius measured with a wet thermometer.
What we know about wet bulb thermometer is a mercury-wrapped mercury thermometer that can measures usually both temperature and humidity, so it shows a different temperature than what we see on weather forecasts through local media or mobile apps.
Higher humidity makes the heat more uncomfortable for the human body, because humidity makes it harder for sweat to evaporate, which cools the body.
In cases where the temperature and humidity are not high at the same time, the temperature of the wet bulb thermometer will not be even close to the human upper limit, says Colin Raymond, a researcher of extreme heat at NASA’s postdoctoral studies at the Jet Propulsion Laboratory.
However, when both the humidity and the temperature are very high, the temperature of the wet bulb thermometer reaches “dangerously high levels”. For example, if the air temperature is 46 degrees and the humidity is low (about 30 percent), the temperature of the wet thermometer will be only 30 degrees.
On the other hand, the air temperature can be 39 degrees, and the humidity 77 percent, and then the temperature of the wet thermometer will be as high as 35 degrees. People cannot survive if both the temperature and the humidity are too high, because in such conditions they cannot regulate their body temperature.
Above 40 degrees, the body becomes hyperthermic, which leads to an accelerated pulse, dizziness, cessation of sweating, fatigue and coma. At 35 degrees, the wet bulb temperature does not cause instant death. It is estimated that the heat becomes unbearable after three hours.
These (approximate) data were obtained thanks to studies in which the subjects stayed in hot water pools until the moment when their body temperature would start to rise uncontrollably. Also, it is difficult to say that exactly 35 degrees measured with a wet thermometer is a lethal temperature. Raymond thinks that it is in the range of 34 to 36.5 degrees.
Although a person cannot survive a wet bulb temperature higher than 35 degrees, even lower temperatures can be deadly. Important factors are direct sun exposure and physical activity.
Fever is also more dangerous for people who have difficulty regulating body temperature – and these are the elderly, people with certain health problems (such as obesity), or those who take medications such as antipsychotics. Due to all these risk factors, heat can be fatal even when the temperature is below 35 degrees (measured with a wet thermometer).
In the past, that temperature was recorded in only a few places in the world. From the late 1980s until today, the hot spots have been in the Indus Valley, ie in central and northern Pakistan and along the southern coast of the Persian Gulf.
However, there are more and more places where that temperature is reached in an hour or two, and with global warming, that will happen more and more often. Locations that will be at risk in the next 30 to 50 years are northwestern Mexico, northern India, southeast Asia, and west Africa.
Unfortunately, even if greenhouse gas emissions stop at this point, it is too late to change the outcome. “I think heat problems are inevitable for those regions in the near future, I just hope the list of endangered areas doesn’t grow.”