Human Tolerance to Atmospheric Pressure: Diving Depths and Extreme Conditions
What is the Maximum Number of Atmospheres the Human Body Can Handle?
Understanding the limits of human tolerance to atmospheric pressure is crucial for both divers and occupational health specialists. This article delves into how far the human body can stay underwater and what risks are associated with high-pressure environments.
The Basics of Atmospheric Pressure
Awareness of atmospheric pressure is critical for anyone involved in diving or working in enclosed pressurized environments. At sea level, the atmospheric pressure is approximately 1 atmosphere (atm). As altitude increases, the pressure decreases. For divers, the pressure increases proportionally with the depth below the surface.
Diving Depths and Atmospheric Pressure Tolerance
When diving, the pressure around a diver increases by 1 atmosphere for every 33 feet (10 meters) of depth gained. This means that at sea level, the ambient pressure is 1 atm. At a depth of 10 meters, the pressure is 2 atmospheres (2 atm), and at 20 meters, it is 3 atm, and so on.
Humans can generally withstand pressures up to about 4 to 5 atmospheres. This is similar to what divers experience in typical scuba diving operations. With specialized equipment and training, divers can handle even higher pressures, though this is beyond standard recreational diving.
Special Situations and Extreme Tolerance
Reports suggest that humans can withstand significantly higher pressures under certain conditions. For example, when submerged in water, the body can tolerate much greater g-forces compared to when in air. It has been noted that in water, a person might be able to withstand pressures as high as 17 g-forces, though this is not the same as atmospheric pressure.
In addition, specialized equipment such as different gas mixtures can increase the human tolerance to atmospheric pressure. Research has shown that when divers are provided with specific gas mixtures designed for high-pressure environments, the tolerance for pressure can be vastly increased. The current world record for simulated high-pressure testing was achieved by Mr. Theo Mavrostomos, who had to withstand a pressure of 71.1 bar during a test conducted in a pressure chamber, equivalent to diving to a depth of 701 meters (2,296 feet).
Health Risks Associated with High Atmospheric Pressures
At 5 bars (5 atm), which is around five times the normal atmospheric pressure, the oxygen in air becomes toxic to the body. Nitrogen, which is normally dissolved in the blood in small amounts, can dissolve in excess in the blood, leading to a condition known as “the bends.” Immediate medical intervention is required to prevent severe health risks.
To understand the depth at which these pressures are experienced, it’s important to note that breathing air humans can typically go down to around 350 feet without special protective gear. Beyond this depth, the partial pressure of oxygen in the air reaches critical levels and can be lethal. Utilizing mixed gases, however, allows divers to reach much greater depths. The current world record for underwater diving using a specific gas mixture is approximately 318 meters (1,040 feet), though this is for short periods and requires lengthy decompression to avoid decompression sickness.
Conclusion
The human body has a remarkable ability to adapt to certain levels of atmospheric pressure, especially when adequately trained and equipped. However, exceeding a certain threshold, such as 10 atmospheres, is not advisable and could lead to severe health complications or even permanent damage. The key to safe diving and working in pressurized environments is understanding and respecting these limits.