Difference Between Nitrox And Air

Diving is an exhilarating activity that allows people to explore underwater worlds, teeming with life and adventure. Two common gases used in diving are Nitrox and Air, each with distinct properties and benefits. Understanding the differences between these gases is crucial for divers to make informed decisions about their underwater experiences.

Nitrox, also known as enriched air, contains a higher percentage of oxygen compared to regular air. This composition allows divers to enjoy longer bottom times and reduces the risk of decompression sickness. In contrast, standard air is composed of approximately 21% oxygen and 79% nitrogen, which is sufficient for most recreational dives but offers fewer benefits than Nitrox.

The choice between Nitrox and Air can significantly impact a diver’s safety, experience, and overall enjoyment. Nitrox requires special training and equipment, but its benefits often outweigh these considerations for many divers. On the other hand, Air is widely accessible and requires no additional certifications, making it a convenient choice for many. Understanding these differences helps divers select the best gas for their specific needs.

Basics of Diving Gases

Definition of Nitrox

Nitrox, also known as enriched air, is a breathing gas used in scuba diving. It contains a higher percentage of oxygen than regular air. Typically, Nitrox mixtures have an oxygen content between 32% and 36%, while the remainder is nitrogen. The increased oxygen percentage in Nitrox provides several benefits to divers, including extended bottom times and a reduced risk of decompression sickness.

Definition of Air

Air used in diving refers to the natural atmospheric air compressed into scuba tanks. It consists of approximately 21% oxygen and 79% nitrogen, with trace amounts of other gases like argon and carbon dioxide. Standard air is widely used in recreational diving and is sufficient for most dive profiles. Its simplicity and availability make it a popular choice for divers of all levels.

Common Uses in Diving

Recreational Diving: Both Nitrox and air are used in recreational diving. Nitrox is preferred for longer dives, while air is used for standard dive profiles.

Technical Diving: Technical divers often use Nitrox for decompression dives due to its benefits in reducing nitrogen absorption.

Professional Diving: Commercial and scientific divers use Nitrox to increase safety margins and improve efficiency underwater.


Air Composition

Air is a mixture of gases, primarily composed of:

  • Oxygen: 21%
  • Nitrogen: 79%
  • Trace Gases: Argon, carbon dioxide, and others

The standard air composition makes it suitable for a wide range of diving activities. Its availability and ease of use are key advantages for divers.

Nitrox Composition

Nitrox has a higher oxygen content than standard air, typically ranging from 32% to 36%. Common Nitrox mixtures include:

  • Nitrox 32: 32% oxygen, 68% nitrogen
  • Nitrox 36: 36% oxygen, 64% nitrogen
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The increased oxygen percentage in Nitrox helps reduce the amount of nitrogen absorbed by the body, which is beneficial for longer and deeper dives.

Oxygen and Nitrogen Levels in Both


  • Oxygen: 21%
  • Nitrogen: 79%


  • Oxygen: 32% to 36%
  • Nitrogen: 64% to 68%

The higher oxygen content in Nitrox reduces nitrogen absorption, which is advantageous for divers.

Benefits of Nitrox

Extended Bottom Time

One of the primary benefits of using Nitrox is the ability to stay underwater longer. The increased oxygen content reduces the nitrogen absorption rate, allowing divers to extend their bottom times. This is particularly useful for dive sites with significant attractions or for photographers who need more time to capture the perfect shot.

Reduced Nitrogen Absorption

Nitrox decreases the amount of nitrogen a diver absorbs during a dive. Lower nitrogen levels in the body reduce the risk of decompression sickness (DCS), commonly known as “the bends.” This benefit is especially important for repetitive dives, where nitrogen accumulation can become a concern.

Lower Risk of Decompression Sickness

Using Nitrox can lower the risk of decompression sickness. DCS occurs when nitrogen bubbles form in the bloodstream and tissues due to rapid ascents or insufficient decompression stops. With Nitrox, the reduced nitrogen absorption minimizes this risk, enhancing diver safety.

Risks of Nitrox

Oxygen Toxicity

One of the risks associated with Nitrox is oxygen toxicity. High oxygen concentrations can become toxic at increased pressures, posing a serious risk to divers. Symptoms of oxygen toxicity include convulsions, visual disturbances, and dizziness. It is crucial for divers to monitor their depth and oxygen exposure to avoid this risk.

Need for Special Training

Diving with Nitrox requires special training. Divers must learn to calculate safe exposure limits and understand the risks of oxygen toxicity. Nitrox courses teach divers how to use Nitrox safely, plan dives accurately, and use Nitrox-compatible equipment. Certification is essential to ensure safety while using Nitrox.

Equipment Considerations

Using Nitrox involves specific equipment considerations. Standard scuba gear can often be used, but some modifications are necessary:

  • Nitrox-compatible dive computer: Essential for monitoring oxygen levels and ensuring safe dive profiles.
  • Properly labeled tanks: Tanks must be cleaned for oxygen service and clearly marked to avoid contamination.
  • Oxygen analyzers: Used to verify the oxygen content of Nitrox mixtures before diving.


Recreational Diving

Recreational diving is the most common type of diving and is typically conducted at depths less than 130 feet (40 meters). Both Nitrox and Air are used, but Nitrox is favored by many divers for its benefits. Recreational divers often use Nitrox to:

  • Extend bottom time: The higher oxygen content allows for longer dives without exceeding no-decompression limits.
  • Reduce nitrogen absorption: Lower nitrogen levels reduce the risk of decompression sickness, especially during repetitive dives.
  • Enhance safety: Nitrox can offer a safer profile for those who dive frequently or have longer dive times.

Technical Diving

Technical diving involves deeper dives, extended bottom times, and more complex dive profiles than recreational diving. Nitrox is commonly used in technical diving for several reasons:

  • Decompression dives: Nitrox is used to reduce nitrogen loading and help manage decompression stops.
  • Mixed gas diving: Technical divers often use Nitrox as part of a gas blend to optimize their dive profiles.
  • Safety margins: The reduced nitrogen absorption helps manage the risks associated with deeper and longer dives.

Professional Diving

Professional diving includes commercial, scientific, and military diving. Nitrox is used in these fields to enhance diver efficiency and safety:

  • Commercial diving: Nitrox can increase bottom time, allowing divers to complete tasks more effectively.
  • Scientific diving: Researchers benefit from longer dive times, enabling more comprehensive data collection.
  • Military diving: Nitrox is used to reduce decompression sickness risk and improve mission success rates.
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Equipment Differences

Standard Scuba Gear for Air

Standard scuba gear for air includes:

  • Regulator: Delivers air from the tank to the diver.
  • Buoyancy Control Device (BCD): Helps maintain neutral buoyancy.
  • Dive computer: Tracks depth, time, and decompression status.
  • Tank: Stores compressed air.

This equipment is widely available and suitable for most recreational dives.

Modified Gear for Nitrox

Diving with Nitrox requires some modifications to standard scuba gear:

  • Nitrox-compatible regulator: Must be cleaned for oxygen service to prevent fire hazards.
  • Nitrox-specific dive computer: Tracks oxygen exposure and ensures safe dive profiles.
  • Labeled tanks: Clearly marked to indicate they contain Nitrox, preventing accidental use.

These modifications ensure safety and compliance with diving standards.

Importance of Proper Labeling

Proper labeling of Nitrox tanks is crucial for several reasons:

  • Safety: Prevents accidental use of Nitrox by divers not trained for it.
  • Clarity: Ensures all divers and support staff are aware of the gas mix.
  • Compliance: Meets industry standards and regulations for gas mixtures.

Proper labeling helps avoid confusion and enhances dive safety.

Training Requirements

Basic Scuba Certification for Air

To dive with air, individuals must complete a basic scuba certification course. This course covers:

  • Basic skills: Breathing techniques, buoyancy control, and underwater navigation.
  • Safety protocols: Emergency procedures, dive planning, and risk management.
  • Equipment use: Proper handling and maintenance of standard scuba gear.

Basic certification is essential for safe and enjoyable diving experiences.

Nitrox Certification Requirements

Diving with Nitrox requires additional certification. Nitrox certification courses include:

  • Theory: Understanding oxygen toxicity, nitrogen absorption, and safe depth limits.
  • Practical skills: Analyzing Nitrox mixtures, planning dives, and using Nitrox-compatible equipment.
  • Safety protocols: Managing oxygen exposure and avoiding hazards.

Certification ensures divers can safely use Nitrox and enjoy its benefits.

Training Course Overview

A typical Nitrox certification course includes:

  • Classroom instruction: Covers the principles of Nitrox diving and safety measures.
  • Practical training: Hands-on experience with analyzing gas mixtures and using Nitrox equipment.
  • Certification dive: A supervised dive to demonstrate proficiency with Nitrox.

Completion of the course results in a Nitrox certification card, allowing divers to rent and use Nitrox.

Cost Comparison

Initial Setup Cost

The initial setup cost for diving with air includes:

  • Basic gear: Regulator, BCD, dive computer, and tank.
  • Certification: Basic scuba certification course.

For Nitrox, additional costs include:

  • Nitrox-compatible gear: Modified regulator and Nitrox-specific dive computer.
  • Certification: Nitrox certification course.

These initial costs are higher for Nitrox due to the specialized equipment and training required.

Ongoing Costs

Ongoing costs for air diving are generally lower and include:

  • Tank fills: Regular air fills are widely available and inexpensive.
  • Equipment maintenance: Standard gear maintenance.

For Nitrox, ongoing costs are higher due to:

  • Nitrox fills: More expensive than air fills.
  • Specialized maintenance: Nitrox gear requires more frequent and thorough cleaning.

Divers should consider these ongoing costs when choosing between air and Nitrox.

Cost-Benefit Analysis

While the initial and ongoing costs of Nitrox are higher, the benefits can outweigh these expenses:

  • Extended bottom time: Allows for longer dives, enhancing the diving experience.
  • Reduced decompression risk: Improves safety, particularly for repetitive and deeper dives.
  • Increased safety margins: Provides peace of mind and enhances diver confidence.

The cost-benefit analysis often favors Nitrox for divers who frequently engage in longer or repetitive dives.

Health and Safety

Impact on Diver’s Health

Diving with Nitrox can positively impact a diver’s health by:

  • Reducing nitrogen absorption: Lowers the risk of decompression sickness.
  • Decreasing fatigue: Many divers report feeling less tired after diving with Nitrox.
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However, divers must be aware of the risks associated with oxygen toxicity and manage their exposure carefully.

Precautions and Safety Measures

To dive safely with Nitrox, divers should follow these precautions:

  • Monitor oxygen exposure: Use a Nitrox-compatible dive computer to track oxygen levels.
  • Analyze gas mixtures: Verify the oxygen content of each tank before diving.
  • Stay within limits: Adhere to recommended depth and time limits for Nitrox dives.

These measures help prevent oxygen toxicity and ensure a safe diving experience.

Emergency Procedures

In case of an emergency while diving with Nitrox, divers should:

  • Ascend slowly: Follow safe ascent rates to avoid decompression sickness.
  • Administer oxygen: Use emergency oxygen to treat symptoms of decompression sickness or oxygen toxicity.
  • Seek medical help: Contact emergency services and follow their advice.

Proper training and preparation are essential for managing emergencies effectively.

Environmental Impact

Nitrox and Marine Conservation

Diving with Nitrox can support marine conservation by:

  • Reducing diver impact: Longer bottom times mean fewer dives, reducing disturbance to marine life.
  • Improving safety: Enhanced safety margins help prevent accidents that could harm the environment.

Nitrox can contribute to more sustainable diving practices.

Air and Environmental Considerations

Diving with air also has environmental considerations:

  • Frequency of dives: More frequent dives can increase environmental impact.
  • Nitrogen absorption: Higher nitrogen levels can lead to more decompression-related incidents, potentially affecting marine life.

Divers should practice responsible diving to minimize their impact.

Sustainability Practices

To promote sustainability, divers should:

  • Limit dive frequency: Reduce the number of dives to minimize disturbance.
  • Follow best practices: Adhere to responsible diving guidelines, such as avoiding contact with marine life and respecting protected areas.
  • Use Nitrox wisely: Choose Nitrox for longer dives to reduce the overall number of dives needed.

Sustainable diving practices help protect marine environments for future generations.

Common Misconceptions

Misunderstandings about Nitrox Benefits

There are several common misunderstandings about Nitrox benefits:

  • Nitrox is only for deep dives: Nitrox is beneficial at various depths, not just deep dives.
  • Nitrox eliminates decompression sickness: While it reduces the risk, it does not eliminate it entirely.
  • Nitrox is unsafe: With proper training and equipment, Nitrox is safe and beneficial.

Educating divers about these benefits can help dispel these myths.

Myths about Air and Diving Safety

Several myths exist about air and diving safety:

  • Air is always safe: While standard air is generally safe, divers must still follow proper protocols to avoid risks.
  • Air is better than Nitrox: This depends on the dive profile and individual needs. Nitrox can offer significant advantages for certain dives.
  • No need for training: Even diving with air requires proper training and certification to ensure safety.

Frequently Asked Questions

What is the main difference between Nitrox and Air?

The main difference between Nitrox and Air is their oxygen content. Nitrox has a higher percentage of oxygen (usually between 32% and 36%), while standard Air contains about 21% oxygen. This increased oxygen content in Nitrox allows for longer dive times and a reduced risk of decompression sickness.

Why do divers use Nitrox?

Divers use Nitrox primarily to extend their bottom times and decrease the amount of nitrogen absorbed into their bodies. This can reduce the risk of decompression sickness and allow for longer, more enjoyable dives. However, Nitrox requires special training and equipment modifications.

Is Nitrox safer than Air?

Nitrox can be safer than Air in terms of reducing the risk of decompression sickness due to lower nitrogen absorption. However, it also carries the risk of oxygen toxicity if used improperly. Proper training and adherence to safety protocols are essential when using Nitrox.

Do I need special equipment for Nitrox?

Yes, diving with Nitrox requires some specialized equipment. Most notably, a Nitrox-capable dive computer is necessary to monitor oxygen levels accurately. Additionally, tanks used for Nitrox must be properly cleaned and labeled to prevent contamination.

How do I get certified to use Nitrox?

To get certified to use Nitrox, divers must complete a specialized training course offered by recognized diving organizations. The course covers the benefits and risks of Nitrox, proper usage, and safety protocols. Certification ensures that divers can safely plan and execute dives using Nitrox.


Choosing between Nitrox and Air depends on a diver’s goals and experience level. Nitrox offers extended bottom times and reduced nitrogen absorption, making it a valuable option for those seeking longer and safer dives. However, it requires additional training and equipment modifications.

Ultimately, both Nitrox and Air have their own advantages and are suitable for different types of dives. Understanding these gases’ properties and benefits allows divers to make informed choices that enhance their underwater adventures while prioritizing safety and enjoyment.

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