Understanding Decompression Time: How Long Does It Take to Safely Surface After Diving?

Diving is an exhilarating experience that allows us to explore the depths of the ocean and witness the wonders of the underwater world. However, as thrilling as it may be, diving also comes with its own set of risks, particularly when it comes to decompression sickness. But how long does it take to safely decompress after a dive? In this article, we’ll delve into the intricacies of decompression time and provide you with all the information you need to know to ensure a safe and enjoyable diving experience.

What is Decompression and Why is it Important?

The Physics of Decompression

Gases in the Diving Environment

Diving involves breathing gas mixtures, which include oxygen, nitrogen, and other gases. These gases dissolve in the blood and body tissues, leading to saturation. The time it takes for the body to eliminate these excess gases is called decompression time.

Pressure Changes During Diving

During a dive, the diver experiences a change in pressure as they descend into the water. As the depth increases, the pressure also increases. When the diver surfaces, the pressure rapidly decreases, leading to the release of gases from the body tissues. This can cause a range of symptoms, including joint pain, fatigue, and even more severe complications.

Decompression Sickness

Decompression sickness, also known as the bends, occurs when the pressure change causes gases to form bubbles in the bloodstream. These bubbles can cause damage to the joints, nervous system, and other organs, leading to serious health problems.

The Importance of Decompression Time

Decompression time is essential for the safe and healthy return to the surface after a dive. The amount of time required for safe decompression depends on several factors, including the depth of the dive, the gas mixture used, and the individual’s personal health and fitness level. Understanding decompression time is critical for divers to avoid decompression sickness and other complications.

The Risks of Decompression Sickness

  • Decompression sickness, also known as the bends, is a condition that can occur when divers ascend too quickly from deep dives, leading to a rapid reduction in pressure that can cause gas bubbles to form in the bloodstream.
  • The risks of decompression sickness can be severe, including neurological symptoms such as headaches, dizziness, and confusion, as well as more serious conditions such as paralysis, seizures, and even death.
  • Factors that can increase the risk of decompression sickness include a history of previous episodes, preexisting medical conditions, and the depth and duration of the dive.
  • It is important for divers to understand the risks of decompression sickness and to follow proper decompression procedures to avoid these complications.

Factors Affecting Decompression Time

Key takeaway: Decompression time is the period required for a diver to safely return to the surface after a dive, and it is essential for avoiding decompression sickness. Factors affecting decompression time include depth, dive profile, breathing gas, physical conditioning, and fitness. Divers must understand the risks of decompression sickness and follow proper decompression procedures to ensure a safe and enjoyable diving experience.

Depth and Dive Profile

The depth and dive profile of a dive are critical factors that can significantly impact decompression time. As divers descend, the pressure surrounding them increases, and this increase in pressure affects the body’s tissues, including the gas spaces in the body, such as the lungs and blood.

The deeper a diver goes, the longer it takes for the body to eliminate the excess inert gas that has been absorbed during the dive. The deeper the dive, the greater the risk of decompression sickness (DCS), also known as the bends, which can occur when the pressure difference between the inert gas in the body and the surrounding water becomes too great.

Dive profile, or the pattern of a dive, including the depth and time spent at each depth, can also impact decompression time. A dive with a steep descent and rapid ascent, such as a shallow dive, can increase the risk of DCS, as the body may not have enough time to eliminate the excess inert gas. In contrast, a dive with a more gradual descent and longer time spent at depth, such as a deep dive, can increase the risk of oxygen toxicity, which can also impact decompression time.

Understanding the relationship between depth, dive profile, and decompression time is critical for divers to ensure safe and effective decompression. Divers must carefully monitor their dive profiles and make appropriate adjustments based on the depth and time spent at each depth to ensure a safe and efficient ascent.

Breathing Gas Mix

When discussing decompression time, it is essential to consider the breathing gas mix used during the dive. The gas mix refers to the composition of the breathing gas, which is usually a combination of oxygen, nitrogen, and sometimes other gases like helium. The gas mix can have a significant impact on decompression time, as it affects the rate at which the body absorbs and eliminates inert gases.

One of the primary factors to consider is the partial pressure of oxygen (PO2) in the breathing gas mix. The higher the PO2, the faster the body can eliminate inert gases. However, diving with high PO2 can also pose risks, such as oxygen toxicity, which can shorten the safe dive time.

Another important factor is the partial pressure of nitrogen (PN2) in the breathing gas mix. The higher the PN2, the slower the body absorbs inert gases. However, diving with a high PN2 can also increase the risk of decompression sickness, which can lengthen the decompression time.

In addition to PO2 and PN2, the helium content in the gas mix can also affect decompression time. Helium has a lower narcotic threshold than nitrogen, which means it causes less narcosis at a given pressure. This can reduce the risk of decompression sickness, allowing for a shorter decompression time.

It is important to note that the optimal gas mix for a dive depends on various factors, such as the depth, duration, and type of dive. Divers must carefully consider these factors when selecting the appropriate gas mix for their dive.

Physical Conditioning and Fitness

Physical conditioning and fitness play a crucial role in determining the amount of time it takes for a diver to safely surface after a dive. Several factors related to physical fitness can impact decompression time, including:

  • Cardiovascular fitness: A diver with higher cardiovascular fitness can handle physical exertion more efficiently, allowing them to spend more time underwater without building up excessive amounts of carbon dioxide or lactic acid. This can affect the decompression time required for the dive.
  • Body composition: The composition of a diver’s body can also impact decompression time. Divers with a higher percentage of body fat may require longer decompression times than those with lower body fat percentages, as body fat can affect buoyancy and can slow down the elimination of excess nitrogen from the body.
  • Respiratory fitness: The ability to breathe efficiently and effectively is essential for a diver. Divers with higher respiratory fitness can take in more oxygen and eliminate carbon dioxide more efficiently, which can affect the decompression time required for the dive.
  • Physical activity during the dive: The level of physical activity during the dive can also impact decompression time. Divers who engage in more physical activity, such as swimming or exploring underwater caves, may require longer decompression times than those who remain stationary during the dive.

It is important for divers to be aware of their physical conditioning and fitness level when planning a dive. Divers who are out of shape or have not been active for an extended period of time may need to take extra precautions and allow for additional decompression time to ensure their safety. Additionally, divers should consult with a medical professional before embarking on a dive, especially if they have any underlying medical conditions or concerns.

Stages of Decompression

Surface Interval

The surface interval is the period of time between the time a diver leaves the water and the time they are considered completely safe to resurface. This period can vary depending on a number of factors, including the depth of the dive, the duration of the dive, and the type of dive.

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It is important to note that the surface interval is not the same as the decompression time, which is the time a diver spends underwater during the ascent. The surface interval is simply the time between leaving the water and resurfacing.

The length of the surface interval can be affected by a number of factors, including the type of dive and the conditions at the surface. For example, a shallow dive with good visibility may have a shorter surface interval than a deep dive with poor visibility.

In general, the longer the dive and the deeper the dive, the longer the surface interval will be. It is important to follow the recommended surface interval for your dive to ensure that you are safe to resurface. Failure to follow the recommended surface interval can result in decompression sickness, also known as “the bends.”

Decompression sickness is a serious condition that can cause a variety of symptoms, including joint pain, muscle spasms, and neurological symptoms. It is important to follow the recommended surface interval to avoid these symptoms and ensure a safe and enjoyable dive.

Safety Stop

The safety stop is a crucial stage in the decompression process, and it involves a gradual ascent from the depth of the dive to the surface. This stage is designed to reduce the risk of decompression sickness (also known as “the bends”) by allowing nitrogen to dissipate from the diver’s body gradually.

The length of the safety stop depends on several factors, including the depth of the dive, the duration of the dive, and the type of gas used. Generally, the safety stop is recommended to last for at least three minutes, but it can be longer depending on the circumstances.

During the safety stop, divers should remain at the depth they were at when they started the stop and should not ascend any further until they reach the surface. This is because the risk of decompression sickness is highest during the ascent, and by remaining at the same depth, divers can minimize this risk.

It is important for divers to monitor their breathing during the safety stop and to ensure that they are breathing the correct gas mixture. If a diver is using enriched air nitrox (EANx), they should switch to a normal air breathing mixture during the safety stop to reduce the risk of oxygen toxicity.

Overall, the safety stop is a critical component of the decompression process, and divers should take it seriously to ensure their safety and well-being after a dive.

Final Decompression Stop

The final decompression stop is the last stage of the decompression process, which takes place after the diver has completed the mandatory safety stop. This stage is crucial in ensuring that the diver has fully eliminated the excess inert gas that has accumulated in the tissues during the dive.

During the final decompression stop, the diver remains at a fixed depth for a specified period of time, typically ranging from 5 to 15 minutes, depending on the dive profile and the decompression algorithm used. The duration of the final decompression stop is determined by the algorithm and takes into account the depth and duration of the dive, as well as the rate at which the inert gases can be eliminated from the diver’s tissues.

The final decompression stop is often the longest and most critical part of the decompression process, as it allows the diver to fully eliminate the accumulated inert gas and reduce the risk of decompression sickness (DCS). The longer the final decompression stop, the lower the risk of DCS, but it also means that the diver will need to spend more time underwater during the dive.

It is important to note that the final decompression stop should not be cut short or skipped altogether, as this can significantly increase the risk of DCS. Divers must follow the decompression schedule and algorithm provided by their dive computer or dive tables, and should never exceed the maximum allowable decompression time or safety limits.

Overall, the final decompression stop is a critical stage in the decompression process that ensures the safe and gradual elimination of inert gases from the diver’s tissues, reducing the risk of decompression sickness and allowing the diver to safely surface after the dive.

Monitoring Decompression Progress

Using a Dive Computer

A dive computer is an essential tool for monitoring decompression progress during a dive. It is a sophisticated device that calculates the time and depth of the dive, and it provides real-time information on the diver’s remaining safe decompression time. The dive computer also monitors the gas mixture being breathed by the diver and alerts the diver if the gas mixture is not within safe limits.

Dive computers come in various types, including wrist-mounted and console-mounted models. Wrist-mounted dive computers are more popular because they are convenient and easy to use. Console-mounted dive computers are more suited for technical diving operations and are usually found in professional diving environments.

When using a dive computer, it is important to follow the manufacturer’s instructions and recommendations. This includes setting the correct parameters, such as the maximum operating depth and the type of gas being used. It is also important to calibrate the dive computer before each dive and to perform regular maintenance checks to ensure its accuracy.

The dive computer provides the diver with a clear display of the remaining safe decompression time, allowing the diver to safely plan the ascent and avoid the risk of decompression sickness. The dive computer also provides an audible and visual alarm if the diver exceeds the safe decompression limits, providing an additional layer of safety.

In summary, using a dive computer is a critical component of monitoring decompression progress during a dive. It provides real-time information on the diver’s remaining safe decompression time, allows for safe planning of the ascent, and helps to avoid the risk of decompression sickness.

Manual Decompression Tables

Manual decompression tables are a method of determining the safe ascent time for divers who have completed a dive at a depth greater than 60 feet. These tables provide a detailed guide for divers and dive tables to calculate the time it takes to safely decompress from a dive, based on factors such as depth, time spent underwater, and the type of gas used for the dive.

Manual decompression tables are used by divers who prefer a more conservative approach to decompression, and who want to avoid the risk of decompression sickness. The tables are based on a mathematical model that calculates the amount of time required for a diver to eliminate the excess inert gas that has accumulated in their body during the dive.

To use manual decompression tables, divers must first determine the maximum operating depth (MOD) of their dive and the type of gas they will be using. The table then provides a set of predetermined time intervals, based on the MOD and gas type, that the diver must follow to safely decompress from the dive. The tables are designed to be used in conjunction with a dive computer, which can provide real-time feedback on the diver’s depth, time, and decompression status.

One of the advantages of using manual decompression tables is that they provide a more conservative approach to decompression than dive computers, which can reduce the risk of decompression sickness. However, they require a higher level of knowledge and skill to use effectively, and may not be suitable for all divers. Divers who are interested in using manual decompression tables should receive proper training and instruction from a qualified diving professional.

How Long Does it Take to Decompress Safely?

The 15-Minute Rule

When it comes to safe decompression, one of the most important rules to follow is the 15-minute rule. This rule states that divers should wait for at least 15 minutes after surfacing before they start to travel away from the dive site. This time allows the body to eliminate the excess nitrogen that has accumulated in the tissues during the dive.

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It’s important to note that the 15-minute rule applies to all types of diving, including recreational and technical diving. Additionally, it applies to all types of diving equipment, including open-circuit and closed-circuit rebreathers.

The reason for this rule is that the body needs time to off-gas the excess nitrogen that has accumulated in the tissues during the dive. Nitrogen is a gas that dissolves in the blood and tissues during a dive, and as the diver ascends, the pressure decreases, causing the nitrogen to come out of solution and form bubbles. These bubbles can cause decompression sickness, also known as “the bends,” if they form too quickly or in the wrong place in the body.

By waiting for 15 minutes after surfacing, the body has time to off-gas enough nitrogen to minimize the risk of decompression sickness. However, it’s important to note that this rule is not a guarantee against decompression sickness, and divers should still follow proper decompression procedures and guidelines to minimize the risk.

It’s also important to note that the 15-minute rule is just one part of a larger set of guidelines and procedures that divers use to minimize the risk of decompression sickness. Divers should also follow proper dive planning, dive execution, and decompression procedures to ensure a safe and enjoyable dive.

Factors Affecting Decompression Time

Decompression time is a critical aspect of safe diving, and various factors can affect it. Understanding these factors can help divers to plan their dives more effectively and ensure their safety. The following are some of the factors that can affect decompression time:

Dive Depth

The deeper a diver goes, the longer it takes to decompress safely. This is because the pressure difference between the surface and deeper levels increases with depth, and the body needs more time to adjust to the reduced pressure at the surface. As a result, deeper dives require longer decompression stops.

Dive Time

The longer a diver stays underwater, the longer it takes to decompress safely. This is because the body accumulates more inert gas during longer dives, and it takes more time for the gas to dissipate from the body. Longer dives require more extensive decompression stops.

Diving History

A diver’s previous diving history can also affect decompression time. Divers who have a history of decompression sickness or have recently completed a series of repetitive dives may require longer decompression stops to minimize the risk of DCS.

Personal Factors

Individual factors such as age, fitness level, and medical history can also affect decompression time. For example, older divers or those with pre-existing medical conditions may require longer decompression stops to ensure their safety.

Equipment Factors

Equipment factors such as the type of scuba gear used, the breathing gas used, and the quality of the equipment can also affect decompression time. Divers who use outdated or poorly maintained equipment may be at a higher risk of DCS.

Understanding these factors can help divers to plan their dives more effectively and ensure their safety. By taking into account the factors that can affect decompression time, divers can avoid the risk of decompression sickness and ensure a safe and enjoyable diving experience.

Decompression Sickness Prevention

Pre-Dive Preparation

  • Importance of Pre-Dive Preparation

Before diving, it is essential to prepare both physically and mentally to ensure a safe and enjoyable diving experience. Pre-dive preparation includes several critical steps that can help prevent decompression sickness and other diving-related injuries.

  • Stretching and Warm-Up

Stretching and warming up before diving can help prevent injury and increase flexibility. This is particularly important for divers who have been inactive for a while or who have a pre-existing medical condition. A simple warm-up routine can include light stretching and movement to get the blood flowing and the muscles ready for the dive.

  • Proper Equipment Check

Proper equipment check is crucial to ensure that all the necessary equipment is in good working order. Divers should inspect their gear before each dive, paying particular attention to the regulator, buoyancy control device, and dive computer. This will help prevent equipment-related issues that can lead to decompression sickness or other diving-related injuries.

  • Familiarization with Dive Site

Familiarization with the dive site is also essential to prevent decompression sickness. Divers should take the time to explore the dive site before diving and become familiar with the underwater terrain, currents, and potential hazards. This will help prevent accidents and ensure that divers are aware of their surroundings during the dive.

  • Mental Preparation

Mental preparation is also crucial to prevent decompression sickness. Divers should take the time to relax and clear their minds before diving. This can include deep breathing exercises, visualization, or meditation. By mentally preparing for the dive, divers can help reduce stress and anxiety, which can lead to decompression sickness or other diving-related injuries.

Overall, pre-dive preparation is an essential aspect of preventing decompression sickness and ensuring a safe and enjoyable diving experience. By taking the time to stretch, inspect equipment, familiarize themselves with the dive site, and mentally prepare for the dive, divers can help prevent injuries and enjoy their time underwater.

Post-Dive Procedures

Proper post-dive procedures are essential for decompression sickness prevention. The following steps should be followed after each dive:

  1. Stay in the water for a short time: After surfacing, it is important to stay in the water for a short period, typically between 5-15 minutes, to allow the body to adjust to the changes in pressure.
  2. Breathe slowly and deeply: After surfacing, take slow and deep breaths to ensure that the body is getting enough oxygen.
  3. Do not smoke or drink alcohol: Smoking and alcohol consumption can increase the risk of decompression sickness, so it is important to avoid these activities after diving.
  4. Stay hydrated: Drinking plenty of water can help to prevent dehydration, which can contribute to decompression sickness.
  5. Monitor for signs of decompression sickness: It is important to monitor for signs of decompression sickness, such as pain, fatigue, and numbness, and seek medical attention if necessary.

By following these post-dive procedures, divers can reduce their risk of decompression sickness and ensure a safe and enjoyable diving experience.

Treatment of Decompression Sickness

Diagnosis

The diagnosis of decompression sickness is typically based on a combination of patient history, physical examination, and evaluation of symptoms. Divers should be evaluated for any signs of neurological abnormalities, such as weakness, numbness, or difficulty with coordination. A detailed dive history is also obtained to determine the depth, duration, and type of dive, as well as any potential risk factors.

Treatment

The primary goal of treatment for decompression sickness is to remove the gas bubbles that have formed in the bloodstream and to alleviate symptoms. This can be achieved through a variety of methods, including:

  • Oxygen therapy: Providing oxygen to the patient can help to reduce the size of the gas bubbles and to improve tissue oxygenation. Oxygen can be administered through a mask or nasal cannula.
  • Chamber therapy: In more severe cases, the patient may be placed in a hyperbaric chamber, which can provide higher levels of oxygen and increased pressure to accelerate the elimination of gas bubbles.
  • Medications: Certain medications, such as nitrogen-oxygen therapy, may be used to reduce the amount of gas in the bloodstream and to alleviate symptoms.
  • Rest: Rest is important in the treatment of decompression sickness, as it allows the body to recover and to eliminate the gas bubbles.

In addition to these treatments, the diver should be closely monitored for any signs of progression or worsening of symptoms. If necessary, additional treatments or interventions may be recommended based on the severity and nature of the symptoms.

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It is important to note that the most effective treatment for decompression sickness is prevention. Divers should follow proper decompression procedures, monitor their ascent rates, and avoid flying or traveling to high altitudes immediately after diving. By taking these precautions, divers can significantly reduce their risk of developing decompression sickness.

Recap and Safety Tips

Staying Within No-Decompression Limits

Diving can be a thrilling and rewarding experience, but it’s important to remember that safety should always be the top priority. One of the key factors in diving safety is understanding decompression time, or how long it takes to safely surface after a dive. In this section, we’ll discuss some important rules for staying within no-decompression limits, which are the maximum time limits for safe ascent from a dive.

  • Know Your Limits: One of the most important rules for staying within no-decompression limits is to know your personal limits and the limits of your dive equipment. This includes knowing the maximum depth and time limits for your dive computer or dive table, as well as the safety stops required for your dive.
  • Stay Within Your No-Decompression Limit: It’s important to stay within your no-decompression limit to avoid the risk of decompression sickness, also known as “the bends.” This means ascending slowly and following the safety stops required for your dive.
  • Monitor Your Gas Supply: It’s important to monitor your gas supply throughout the dive and plan your ascent accordingly. This means keeping track of your air or gas consumption and having a backup plan in case you run out of gas.
  • Use a Dive Computer: A dive computer is an essential tool for safe diving and can help you stay within your no-decompression limit. It’s important to use a dive computer that is appropriate for your level of experience and the conditions of your dive.
  • Plan Your Dive: Proper planning is key to staying within no-decompression limits. This includes choosing the right dive site, taking into account factors such as current and visibility, and planning your dive according to your personal limits and the conditions.

By following these rules and staying within your no-decompression limit, you can help ensure a safe and enjoyable diving experience.

Adapting to Different Diving Conditions

Diving conditions can vary greatly depending on factors such as depth, temperature, and current. To ensure safe diving, it is important to adapt to these conditions and adjust dive plans accordingly. Here are some tips for adapting to different diving conditions:

  • Depth: Diving at greater depths requires more time for decompression, so it is important to plan dives that stay within safe limits. Additionally, the deeper you dive, the greater the risk of nitrogen narcosis, a condition that can impair judgment and decision-making.
  • Temperature: Cold water can increase the risk of hypothermia, while warm water can increase the risk of dehydration. It is important to dress appropriately for the water temperature and to stay hydrated throughout the dive.
  • Current: Strong currents can make it difficult to control buoyancy and navigate underwater. It is important to plan dives that take into account the strength and direction of the current, and to have a clear plan for how to navigate and avoid potential hazards.
  • Visibility: Poor visibility can make it difficult to see underwater and navigate safely. It is important to have a dive buddy and to stay within sight of each other at all times. Additionally, it is important to have a compass or other navigation tools in case of emergency.

Overall, adapting to different diving conditions requires preparation, planning, and communication with dive buddies. By taking these steps, divers can reduce the risk of accidents and ensure safe and enjoyable dives.

The Importance of Proper Training and Education

Proper training and education are essential components for any recreational diver. Understanding decompression time and its implications is critical to ensuring safe diving practices. Training programs provide a comprehensive overview of decompression theory, the risks associated with decompression sickness, and the importance of adhering to the established limits of no-decompression time (NDT).

Effective training also emphasizes the significance of monitoring dive profiles and using dive tables or dive computers to calculate decompression time accurately. It teaches divers how to identify and respond to potential decompression emergencies, such as symptoms of decompression sickness, and when to seek medical attention.

Additionally, education on the importance of gas sharing and buddy breathing during the ascent can prevent accidental exposure to excessive pressure, reducing the risk of decompression sickness.

In summary, proper training and education are crucial for understanding decompression time and diving safety. It provides divers with the knowledge and skills necessary to plan and execute safe dives, monitor their decompression status, and respond appropriately to emergencies. By adhering to established safety guidelines and following proper diving practices, divers can significantly reduce the risk of decompression sickness and ensure a safe and enjoyable diving experience.

FAQs

1. How long does it take to decompress after diving?

Answer:

The amount of time it takes to decompress after diving depends on several factors, including the depth and duration of the dive, the type of dive, and the individual’s personal factors such as age, fitness level, and experience. Generally, it is recommended to spend at least 15 minutes at the surface after a dive to allow for adequate decompression. However, this time can vary depending on the specific circumstances of the dive. It is important to follow the recommendations of the dive operator or to consult with a dive medical professional to determine the appropriate decompression schedule for your dive.

2. What are the risks of not decompressing properly after diving?

The risks of not properly decompressing after diving can include decompression sickness, also known as “the bends,” and more severe complications such as lung overexpansion syndrome. Decompression sickness occurs when the body is exposed to the high pressure of the depths and then rapidly decompresses, causing the formation of bubbles in the bloodstream that can cause pain, tissue damage, and other symptoms. Lung overexpansion syndrome can occur when a diver surfaces too quickly and the lungs overexpand, causing damage to the lung tissue. Both of these conditions can be serious and potentially life-threatening, so it is important to follow proper decompression procedures to avoid these risks.

3. How can I speed up the decompression process after diving?

There are several ways to speed up the decompression process after diving, including ascending slowly and gradually, avoiding deep breaths at the surface, and using a safety stop. Ascending slowly and gradually allows the body to adjust to the changing pressure levels and reduces the risk of decompression sickness. Avoiding deep breaths at the surface can also help to reduce the risk of lung overexpansion syndrome. Using a safety stop, which involves pausing at a shallow depth for a few minutes before reaching the surface, can also help to reduce the risk of decompression sickness and allow the body to off-gas any remaining nitrogen.

4. How can I prepare for safe decompression after diving?

Preparing for safe decompression after diving involves following proper dive procedures, including planning the dive, using appropriate dive equipment, and monitoring dive parameters such as depth, time, and gas consumption. It is also important to be physically fit and well-rested before diving, as fatigue and dehydration can increase the risk of decompression sickness. Additionally, it is important to follow the recommendations of the dive operator or to consult with a dive medical professional to determine the appropriate decompression schedule for your dive. Finally, it is important to be aware of the signs and symptoms of decompression sickness and to seek medical attention immediately if they occur.

Making Safe Ascents