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Why do you need to worry about something called 'wet-bulb' temperature?

The measure of heat and humidity is edging closer to the limits of human survivability.

HOUSTON — What is the "wet-bulb" temperature and why do you need to worry about it?

You may have heard about it recently thanks to hot temperatures around the world, and the science behind it can be a little complicated. 

However, essentially the wet-bulb temperature is the threshold for human survivability. 

If heat and humidity are too high, the human body begins to lose the ability to sweat, meaning we can no longer cool ourselves off. 

A critical wet-bulb temperature is the point where a healthy person can survive for only six hours. A 2020 study in Science Advances found that some places on Earth have already hit that threshold.

So where does the name come from? It is the way the measurement is taken. If you wrap a wet cloth around the bulb of the thermometer, evaporating water from the cloth can cause the thermometer to go down, recreating how the human body cools itself off with sweat.

The wet-bulb temperature is the temperature that a wet cloth cools the thermometer down to. However, if the air is humid, less water from the cloth will evaporate, meaning the thermometer will not be cooled off as much and the wet-bulb temperature will be higher.

According to the Washington Post, places like the Persian Gulf and Pakistan have already reached a wet-bulb temperature of 95 degrees. At that point, you can’t sweat enough to avoid overheating. 

Even if you are healthy, find shade, and drink a large amount of water you will still face organ failure. The only real solution is air conditioning. 

As temperatures and humidity rise experts say making sure people have access to air conditioning will take on new importance.

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