Diving Basics
Decompression sickness, or “the bends,” is a danger faced by SCUBA divers when they rise too quickly from deep depths. To avoid decompression sickness, a diver must follow a dive table or dive computer to know how long they can stay at a certain depth before they need to ascend to shallower depths to allow their body time to off-gas.
What is Decompression?
Decompression is a process where a person gradually returns to atmospheric pressure after being exposed to a high pressure environment, such as underwater. This process allows the body to safely offload the excess nitrogen that has built up in the tissues, and prevents the formation of harmful gas bubbles.
There are two main types of decompression sickness (DCS), depending on where the bubbles form:
- Type I DCS, also called bends or smokers bends, occurs when nitrogen bubbles form in the muscles and joints. This is the most common form of DCS, and is generally less severe than Type II DCS.
- Type II DCS, also called chokes or reverse chokes, occurs when nitrogen bubbles form in the lungs. This is less common than Type I DCS, but can be more severe.
Symptoms of decompression sickness can range from mild (joint pain) to severe ( paralysis), and can occur immediately or several hours after exposure to a high pressure environment. If you experience any symptoms of decompression sickness, it is important to seek medical help immediately.
How Does Decompression Work?
The effects of decompression sickness (DCS) were first observed in 1841 by a French physician who noticed that workers who ascended too quickly from deep mines suffered from a range of symptoms, including skin lesions, paralysis, and even death. In the years since, our understanding of DCS has grown exponentially, but the basic principles remain the same.
When you dive, the water pressure around you increases. This higher pressure forces nitrogen gas into your tissues. At depth, the nitrogen is dissolved in your blood and other tissues under high pressure. When you ascend, the surrounding water pressure decreases, and the nitrogen comes out of solution and forms bubbles. If these bubbles expand too quickly, they can cause tissue damage or block blood vessels, leading to a range of symptoms from joint pain to death.
The key to avoiding DCS is to give your body time to adjust to the changing pressures slowly. This is why divers use a dive table or computer to plan their ascent: to make sure they give themselves enough time for the nitrogen bubbles to dissipate safely.
Decompression Sickness
If you dive deeper than about 130 ft (40 m) on a single breath of air, you can get decompression sickness (DCS; “the bends”). DCS happens when dissolved gases come out of solution in your body tissues and form bubbles. These bubbles can block blood flow and cause tissue damage.
What is Decompression Sickness?
Decompression sickness, also called “the bends,” is a condition that occurs when scuba divers rise too quickly from deep waters. Divers who breathe air from tanks are at risk for the bends, although it can also occur in persons who held their breath while swimming to the surface from deep waters.
Symptoms of decompression sickness include joint pain, skin rashes, and swelling of extremities. In severe cases, the bends can cause paralysis or even death. Treatment for decompression sickness is typically with 100% oxygen and recompression in a chamber.
What Causes Decompression Sickness?
There are many factors that can contribute to the development of decompression sickness, but the two most important are:
- The amount of time you spend underwater
- The depth of the dive
The deeper the dive, the greater the risk of decompression sickness. This is because the pressure of the water increases at greater depths, which forces nitrogen into your tissues and bloodstream. When you ascend to shallower depths, this nitrogen is released from your tissues and starts to form bubbles in your blood and body tissues. These bubbles can cause pain, tissue damage, and even paralysis.
Decompression sickness is most commonly seen in divers who ascend too quickly from deep dives. However, it can also occur in shallow dives if you spend a long time underwater. For example, if you stay at a depth of 10 feet (3 meters) for an hour, you will be exposed to the same amount of nitrogen as if you had descended to 60 feet (18 meters) and stayed there for 10 minutes.
How to Prevent Decompression Sickness
At its most basic, decompression sickness occurs when nitrogen bubbles form in the blood and tissues. This can happen when a person ascends too quickly from depth, causing the nitrogen to come out of solution and form bubbles. The severity of symptoms depends on the number of bubbles present, as well as their size and location.
Decompression sickness is most commonly associated with scuba diving, but it can also occur in other situations where nitrogen is present, such as flying or working in high-pressure environments. While decompression sickness is usually not life-threatening, it can be very painful and even disabling.
There are several ways to prevent decompression sickness, including:
- Use a dive computer: This will help you track your depth and time underwater, as well as your ascent rate, to ensure you don’t exceed safe limits.
- Get proper training: Make sure you understand how to use your dive gear properly and know your limitations. Decompression sickness is more likely to occur if you ascend too quickly or exceed your dive limits.
- Follow safe diving guidelines: Don’t push your limits when diving. If you’re feeling uncomfortable or fatigued, end your dive. And be sure to stay within the no-decompression limit for your depth and bottom time.
- Use a safety stop: When ascending from a dive, take a 3-5 minute stop at 15 feet (4.6 meters) to help offgas any remaining nitrogen in your system before resurfacing.
Diving Depths
Divers often ask about maximum depths and decompression stops. There is a simple answer to the first question and a more complicated one to the second. The maximum depth a diver can dive is determined by the percentage of oxygen in the breathing gas. For bottom time limits, we need to consider decompression stops.
How Deep Can You Dive Without Decompression?
Most divers know their dive tables or dive computers like the back of their hand. But how many of us actually know how these devices calculate the no-decompression limit (NDL) for a given dive depth and time? In this article, we’ll take a look at the science behind calculating decompression stops and what differentiates a no-decompression limit from a recommended safety stop.
The NDL is based on two things: the amount of nitrogen that dissolves in your blood and tissues while you’re under pressure, and the amount of time it takes for that nitrogen to return to saturation levels once you start resurfacing. The deeper you go, the more nitrogen dissolves in your body. And, because gases become less soluble as pressure decreases ( Boyle’s Law), the faster nitrogen comes out of solution as you ascend.
What is the Maximum Depth for Diving?
The average depth that a recreational diver can safely dive is 130 feet (40 meters). This is because the atmospheric pressure at that depth is twice that at sea level. For divers who are properly trained and equipped, however, diving deeper than 130 feet is possible.
However, just because a diver can go to greater depths does not mean that it is always safe to do so. There are many factors that need to be considered before a dive, such as the type of equipment being used, the experience of the diver, and the conditions of the water.
For example, dives that are conducted using special breathing apparatus known as closed-circuit rebreathers (CCRs) can safely take place at depths greater than 300 feet (91 meters). These devices recycle the air that a diver breathes, removing carbon dioxide and replacing it with fresh oxygen. This allows a diver to stay underwater for much longer periods of time than if they were using a traditional scuba tank.
Only experienced divers who have been properly trained in the use of CCRs should attempt dives to these depths. Divers who attempt to reach these depths without proper training or equipment put themselves at risk of serious injury or death.
Diving Tables and Computers
To dive without decompression, you must first know your No-Decompression Limits (NDLs). NDLs are different for every dive and every dive computer, and are based on how deep you are, how long you stay there, and how fast you ascent. Decompression sickness happens when you exceed your NDLs and dissolved nitrogen forms bubbles in your blood and tissues.
What are Diving Tables?
Diving tables are devices used by divers to help plan their dives and avoid decompression sickness. Tables give the diver an indication of how long they can stay at a certain depth, and how long they must wait before resurfacing, in order to avoid getting sick.
There are two main types of diving tables: those used by recreational divers, and those used by technical divers. Recreational diving tables are simpler, and only take into account the depth and time of the dive. Technical diving tables are more complex, and take into account factors such as Nitrogen absorption rates and/or decompression gas mixes.
Diving tables are not 100% accurate, and should only be used as a guide. Factors such as a diver’s age, fitness level, and whether they are smoking can all affect a person’s susceptibility to decompression sickness.
In addition to diving tables, many divers also use dive computers to help plan their dives. Dive computers are electronic devices that use algorithms to calculate a dive profile based on the diver’s inputs. Dive computers take into account factors such as the water temperature and the diver’s rate of ascent, which allows them to be more accurate than diving tables.
What are Diving Computers?
Diving computers are devices used by divers to monitor their distance below the water’s surface, and to calculate their decompression stops during a dive. A diving computer can either be an independent device, or built into a diving watch. Most commercial divers, technical divers, and military divers use diving computers as an essential part of their dive gear.
Diving computers use one or more sensors to measure the pressure of the surrounding water, and from this calculation, they derive the depth of the dive. Many diving computers also include sensors for temperature and acceleration. The data from these sensors is used by the computer to make decompression calculations based on a reduction of nitrogen in body tissue during a dive.
Diving Safety
Diving can be a dangerous sport if you don’t take the necessary safety precautions. One of the most important safety precautions is to know your depth limit. How deep can you dive without decompression?
What are the Dangers of Deep Diving?
At depths greater than 60 feet (18 meters), dolphin and whale brains are subject to a condition called nitrogen narcosis. This is similar to the drunkenness humans feel when inhaling high concentrations of nitrogen. For these sea mammals, however, nitrogen narcosis can be fatal.
Diving too deep also puts human beings at risk for this condition, which is why divers must be very careful to avoid going too deep. narcosis can cause a loss of coordination and judgment, leading to accidents. In some cases, it can even causehallucinations.
How to Stay Safe When Deep Diving
Deep diving can be dangerous if you don’t take the proper precautions. The further down you go, the greater the risk of decompression sickness (DCS), which can cause serious health problems or even death.
There are two main ways to help prevent DCS:
- Use a dive computer to help you plan your dives and monitor your progress.
- Use a dive tables to help you plan your dives and monitor your progress.
Dive computers are generally more accurate than dive tables, but both can be useful tools. Be sure to read the instructions carefully and consult with a qualified diving instructor before using either one.