Oxygen Toxicity in Diving: Research Summary

5 min read · 6 July 2026

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Oxygen toxicity: A brief history of oxygen in diving is a 1999 publication by Acott in SPUMS Journal 1999 Volume 29 Number 3. It addresses how oxygen has been used in diving and why excessive exposure matters: oxygen is essential for life, yet at elevated pressure it can affect the nervous system and lungs.

Why can oxygen become toxic underwater?

Oxygen toxicity is the harmful effect of breathing oxygen at a sufficiently high partial pressure or for a sufficiently long exposure. The risk depends on both the oxygen concentration in the breathing gas and the ambient pressure. As a diver descends, pressure rises, so the partial pressure of oxygen can become much greater even if the gas mixture itself is unchanged.

This is a central trade-off in diving physiology. Oxygen supports metabolism, and increasing its proportion in a breathing mixture can reduce exposure to other gases, but it also narrows the conditions under which that mixture can be safely breathed. Depth, duration, workload and the breathing gas all matter when considering exposure.

Partial pressure: the pressure contributed by oxygen within the total breathing-gas pressure.
Central nervous system effects: acute effects of excessive oxygen exposure that can include convulsions, creating an immediate underwater hazard.
Pulmonary effects: effects on the lungs associated with substantial or prolonged oxygen exposure.
Exposure management: the practical balancing of oxygen benefit against pressure- and time-related risk.

What makes oxygen exposure a diving-medicine concern?

An oxygen-related seizure underwater can lead to loss of a regulator, aspiration or drowning. This makes oxygen toxicity more than a laboratory or theoretical concern: it affects decisions about breathing mixtures, depth and exposure time, and it is relevant to both recreational and occupational diving.

Pulmonary oxygen toxicity is a different concern from an acute neurological event. It is associated with accumulated exposure and may become relevant during extended or repeated breathing of oxygen-rich gas, including in hyperbaric settings. The two forms of toxicity involve different patterns of harm, so they should not be treated as interchangeable.

How does pressure shape the risk?

Gas pressure increases with depth, and the partial pressure of each gas in a breathing mixture rises accordingly. A mixture that is suitable in one environment may therefore create excessive oxygen exposure at a greater depth. This pressure dependence is why oxygen planning cannot be separated from the intended dive profile.

Time is also important. A brief exposure at high oxygen partial pressure and a longer exposure at lower pressure pose different physiological questions. Divers and clinicians consider the combined exposure rather than treating oxygen concentration alone as a complete measure of risk.

Why place oxygen’s history in the context of diving?

The title positions Acott’s work at the intersection of diving history and oxygen physiology. The development of diving practices has involved finding ways to deliver useful breathing gas while managing the effects of increased pressure and prolonged exposure. A historical perspective helps readers understand why oxygen became a significant subject in the technical and medical discussion of diving.

Oxygen toxicity also sits alongside other constraints on underwater breathing, including inert-gas effects, decompression and the demands of equipment and operational planning. These issues interact: changing a breathing mixture can alter one risk while introducing another. The subject therefore matters to divers, diving physicians, hyperbaric clinicians and scientific divers working with planned exposures.

What should readers take from the physiology?

The key principle is that oxygen is beneficial within an appropriate exposure range, not harmless at any concentration or pressure. In diving, depth raises oxygen partial pressure, while duration contributes to cumulative exposure. Understanding both factors is fundamental to interpreting oxygen use in breathing gases and hyperbaric environments.

Questions about an individual’s fitness to dive, symptoms after exposure or a specific gas plan require assessment in context. A diving-medicine physician should be consulted when medical decisions or concerns about oxygen exposure arise.

Frequently asked questions

What is oxygen toxicity?

It is harmful physiological effects caused by breathing oxygen at excessive pressure, for excessive duration, or both. In diving, elevated ambient pressure can raise oxygen partial pressure.

Why is oxygen toxicity relevant to divers?

Excessive exposure can affect the central nervous system or lungs. Acute neurological effects are especially dangerous underwater because they can compromise a diver’s ability to breathe safely.

What does Acott’s publication address?

Its title identifies a brief history of oxygen in diving, with oxygen toxicity as its subject. The topic connects the development of diving practice with the physiological risks of oxygen exposure.

Citation details

Title: Oxygen toxicity: A brief history of oxygen in diving
Authors: Acott, CJ
Year: 1999
Published in: SPUMS Journal 1999 Volume 29 Number 3
Repository record: Rubicon Research Repository, handle 123456789/6014

This page is an original summary written by the Rubicon editors from the publication’s bibliographic record. It does not reproduce the paper, its abstract or its data; consult the publication itself for its methods and findings.