Oxygen & Hyperbaric - The basics
HBOT basics: what pressure + oxygen actually do
Last reviewed 13 August 2026. How we write this.
What hyperbaric oxygen therapy actually is, and why both pressure and oxygen matter together.
Hyperbaric oxygen therapy, usually shortened to HBOT, means breathing oxygen at a pressure higher than the air around us at sea level. It is done inside a sealed chamber, where the pressure is raised and the person breathes a much higher concentration of oxygen than normal air provides. Two things are changing at once - the pressure, and the oxygen - and it is the combination that defines the therapy.
Measuring the pressure
Pressure inside a chamber is often described in ATA, or atmospheres absolute. One ATA is roughly the pressure you feel at sea level. Clinical HBOT typically runs somewhere above that, so the body is exposed to more pressure than daily life delivers. The exact figure depends on the setting and is decided by trained staff, not by the person in the chamber.
Why the two effects work together
Raising pressure lets more oxygen dissolve into the blood, and raising the oxygen concentration increases how much is available to dissolve in the first place. Neither alone produces the same effect. This is the mechanism most HBOT research is built on, and it is worth understanding before looking at any claim about what HBOT may or may not do.
- Pressure is raised inside a sealed chamber, measured in ATA.
- The person breathes oxygen at a far higher concentration than ordinary air.
- The point of interest is the extra oxygen carried in blood and reaching tissue.
This lesson is for general education only and is not medical advice. HBOT is a medical procedure carried out under supervision - any question about whether it is relevant to you belongs with a qualified professional.
Related in this classroom
The studies behind this page
- A general overview of hyperbaric oxygen therapy: applications, mechanisms and translational opportunities - Medicina, 2021
Sources for this classroom
Educational content only. Not medical advice, diagnosis or treatment. Always consult a qualified healthcare professional before changing your health regimen.