Air vs. Nitrox

What's the Difference?

Air and Nitrox are both commonly used breathing gases in scuba diving, but they differ in their oxygen content. Air typically contains around 21% oxygen, while Nitrox has a higher oxygen concentration, usually ranging from 32% to 40%. This increased oxygen level in Nitrox allows divers to extend their bottom time and reduce the risk of decompression sickness. However, it also introduces certain limitations, as higher oxygen levels can increase the risk of oxygen toxicity at deeper depths. Therefore, divers using Nitrox need to adhere to specific depth limits and follow proper procedures to ensure their safety. In contrast, air is more versatile and can be used for diving at various depths without such restrictions. Ultimately, the choice between Air and Nitrox depends on the diver's experience, dive plan, and the specific conditions of the dive.


CompositionPrimarily nitrogen and oxygenNitrogen and oxygen with a higher percentage of oxygen than air
Oxygen PercentageApproximately 21%Varies depending on the mix, typically between 22% and 40%
BenefitsStandard breathing gas for most recreational diversAllows for extended bottom times and reduced nitrogen narcosis
DecompressionRequires decompression stops for dives beyond no-decompression limitsAllows for reduced decompression obligations compared to air
Maximum Operating DepthDependent on the diver's certification level and gas consumptionDependent on the specific nitrox mix and the diver's certification level
Gas PlanningBased on no-decompression limits and gas consumption ratesBased on maximum operating depth, oxygen exposure limits, and gas consumption rates
TrainingBasic certification covers air divingAdditional training required for nitrox diving

Further Detail


When it comes to scuba diving, the choice of breathing gas is a crucial decision that can greatly impact the overall diving experience. Two popular options are air and nitrox. While both provide the necessary oxygen for divers, they differ in terms of composition and benefits. In this article, we will explore the attributes of air and nitrox, highlighting their advantages and considerations to help divers make an informed choice.


Air, as the name suggests, is the gas mixture that makes up our atmosphere. It primarily consists of approximately 78% nitrogen, 21% oxygen, and trace amounts of other gases. On the other hand, nitrox, also known as enriched air nitrox (EANx), is a blend of nitrogen and oxygen with a higher oxygen content than regular air. The oxygen percentage in nitrox can vary, but common blends include 32% and 36% oxygen.

Benefits of Air

Air is the most commonly used breathing gas in recreational scuba diving. It offers several advantages, including:

  • Availability: Air is readily available at dive centers and dive resorts worldwide, making it easily accessible for divers.
  • Cost: Air fills are generally less expensive compared to nitrox, making it a more budget-friendly option for divers.
  • Training: Basic scuba diving certifications typically focus on diving with air, so divers can start exploring the underwater world without the need for additional training.
  • Depth Limitations: Air is suitable for recreational diving within the no-decompression limits, allowing divers to explore depths up to 130 feet (40 meters) without requiring decompression stops.
  • Familiarity: Many divers are accustomed to diving with air, as it has been the standard breathing gas for decades, providing a sense of familiarity and comfort.

Benefits of Nitrox

Nitrox, with its higher oxygen content, offers specific advantages that make it an appealing choice for certain diving scenarios:

  • Extended Bottom Time: Nitrox allows for longer dives compared to air due to reduced nitrogen absorption. By decreasing the nitrogen percentage, divers can extend their bottom time within safe limits.
  • Reduced Nitrogen Narcosis: Nitrogen narcosis, often referred to as "the bends," can affect divers at greater depths. With nitrox, the reduced nitrogen content minimizes the risk of narcosis, leading to increased mental clarity and improved safety.
  • Shorter Surface Intervals: As nitrox reduces nitrogen absorption, it shortens the required surface intervals between repetitive dives. This benefit can be particularly advantageous for divers on liveaboards or those seeking to maximize their time underwater.
  • Less Fatigue: Nitrox divers often report feeling less tired after dives, as the reduced nitrogen content can help reduce post-dive fatigue and enhance overall energy levels.
  • Enhanced Safety Margin: Nitrox provides a wider safety margin by reducing the risk of decompression sickness, especially during repetitive dives or when approaching the no-decompression limits.

Considerations for Air Diving

While air is a popular choice, there are a few considerations divers should keep in mind:

  • Depth Limitations: Air has a maximum depth limit of 130 feet (40 meters) due to the risk of nitrogen narcosis and decompression sickness beyond this depth.
  • Repetitive Dives: When planning repetitive dives, divers need to account for longer surface intervals to allow for nitrogen off-gassing.
  • Conservative Dive Profiles: Air requires divers to follow more conservative dive profiles to minimize the risk of decompression sickness.

Considerations for Nitrox Diving

While nitrox offers enticing benefits, divers should consider the following factors:

  • Training: Divers need to complete a specialty course to learn about the specific considerations and safety protocols associated with nitrox diving.
  • Oxygen Toxicity: Higher oxygen percentages in nitrox increase the risk of oxygen toxicity, which can be dangerous if not properly managed. Divers must adhere to the maximum operating depth (MOD) for their specific nitrox blend.
  • Availability: Nitrox may not be available at all dive centers or dive destinations, limiting its accessibility in certain locations.
  • Cost: Nitrox fills are generally more expensive than air fills, which can impact the overall diving budget.


Choosing between air and nitrox depends on various factors, including the diving environment, depth requirements, and personal preferences. Air is widely available, cost-effective, and suitable for recreational diving within depth limits. Nitrox, on the other hand, offers extended bottom time, reduced nitrogen narcosis, and shorter surface intervals, but requires additional training and careful management of oxygen exposure. Ultimately, divers should consider their diving goals, safety considerations, and the availability of gas blends to make an informed decision that enhances their underwater experiences.

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