Human survival limit

People can hold their breath for 3 minutes, fast for 3 days, fast for 3 weeks, but how long can they stay up? How much is the environment tolerant?

Limiting human stamina

Limited to white consciousness

The longest sleepless record in the world belongs to Randy Gardner, who is able to stay awake for 264 hours (about 11 days). Last June, a Chinese man died after staying awake for 11 days to watch football. However, because he used a lot of alcohol and tobacco, it is not possible to confirm the cause of death due to lack of sleep.

The 1999 University of Chicago study in the United States showed that, when not sleeping for 2 consecutive weeks, there was an increase in metabolic syndrome in rats, causing the metabolic rate to rise too fast, burning off excess calories immediately. even when the body is not working.

Radiation exposure limits?

Radiation poses a long-term health risk because it can alter human DNA, leading to the development of cancer cells. According to Peter Caracappa, radiation safety specialist at Rensselaer Polytechnic Institute (USA), the radiation exposure of up to 5 - 6sv (units that measure ionizing radiation) in a few minutes will shred a large amount of radiation. cells make the body unable to recover.

Some workers at the Fukushima nuclear power plant (Japan) exposed from 0.4 to 1 s of radiation per hour. Although surviving through special protective equipment, they still have a high risk of cancer.

The limit suffers from sudden acceleration

Horizontal acceleration strongly affects the human body due to the asymmetry of impact forces. According to an article on Popular Science, the impact of horizontal acceleration is 14 times greater than the gravity of the Earth, causing the internal organs to be torn apart, blood rushing to the feet.

People seem to be able to easily overcome the acceleration in front and behind because of this condition, the head and heart are accelerated at the same time. In the 1940s and 1950s, scientists experimented with attaching jet engines to a sleigh at Edwards Air Force Base in California. The sleigh is moving at 1,013km / h less than a second has stopped suddenly but the participants are still safe.

Limits to adapt to environmental changes

According to a NASA 1958 report, humans can live in conditions of ambient temperature ranging from 4 to 35 degrees Celsius. The maximum temperature can be pushed up if the air humidity is low, because of the amount of clear water. The lower gas the body will easily sweat more and help reduce the body's temperature.

Different individuals can withstand various changes in temperature, pressure or oxygen in the air. Also, whether we adapt or not depends on how long the environment changes. This is because the body can gradually adjust the process of oxygen absorption, as well as metabolism to adapt to external conditions.

Most people will experience hyperthermia after 10 minutes of suffering a temperature of 60 degrees Celsius. Typically, a person dies when body temperature drops to 21 degrees C. However, how long does it take for muscle temperature to The reduction to this limit also depends on how well the person is "accustomed" to the cold and whether the "hibernation" phenomenon occurs.

Our bodies have stable body temperature at 37 degrees Celsius , but if the ambient temperature reduces body temperature, it will cause very significant effects. If your body temperature drops to 35 degrees C, your limbs will shake and it's hard to move. At 32 degrees C, most people will lose consciousness, the body will give up trying to maintain body temperature. The breath decreases and the heart rhythm disturbs when the temperature is 28 degrees C. And when the body temperature is only 20 degrees C, the heart stops beating. However, there has been a case where a girl walked in the weather of -20 degrees C and her body temperature was only 16 degrees Celsius but still saved.

It seems that we are better able to withstand cold than heat. The body's highest temperature that can sustain life is 42 degrees Celsius, because at this temperature the body's essential proteins begin to break down. Compared to the outside temperature, even fully equipped firefighters can only withstand the ambient temperature up to 93 degrees C.

Climbing and diving on the ocean floor

The higher the atmospheric pressure, the lower the air pressure and the more dilute the air is, the lower the oxygen content. We will die when the oxygen concentration in the air drops below 11%. According to calculations by scientists, we will not be able to breathe without oxygen tanks on a height of about 7,900m.

Meanwhile, if we dive to the bottom of the sea without special equipment, we will suffer from lack of oxygen and great pressure of water. Usually a person can dive down to about 18m . But the world record records the greatest depth that humans can dive down to 85m.

And other limits of the body

A normal person has between 3.8 and 5.6 liters of blood . You can lose about 15% of blood in your body without any effect. However, if you lose a larger amount of blood, you will feel dizzy, heart palpitations. When you lose about 40% of your blood, your blood pressure is too low to push blood away and your heart starts to beat. If you exceed 50%, your heart will be unbearable and will lead to death.

More than 60% of our bodies are water , so water is very important. However, drinking too much water is not a good thing, it can even cause us to lose our lives. According to doctors, 10L of water is the maximum amount of water you can drink within 1 hour without diluting the electrolytes in your body causing the muscles to twitch and possibly die.

The magnitude of the sound is measured in decibels. About 30dB is the loudness in quiet villages, while 120dB is the loudness that you can hear at rock shows. The biggest sound we can hear is about 160dB, if the sound is greater than this threshold, it can cause the eardrum to tear. When the sound is 200dB, sound waves with high pressure can even break the lungs, pushing air into the color vessels, causing the blood vessels to die.

Death from electric shock is a very common cause. The cause of death is not the large voltage, but the current (amperes). A current of about 1mA can cause a bit of numbness, while a 200mA current is enough to take away our lives. The resistance of human skin varies from 1,000 Ohms (wet skin) to 100,000 ohms (dry skin), so the corresponding voltage level can be deadly 200V (wet skin) and 20,000V (dry skin). In fact, only 10% of lightning strikes cause death.