The Physics of Pressure - What "Atmospheres Absolute" Actually Means For HBOT

ATA gets thrown around a lot in anything written about hyperbaric oxygen therapy, our Silver Tank runs at 1.3 ATA, Gold at 1.5, Platinum up to 2.0, but it’s rarely actually explained.

It sounds technical enough that most people nod along without quite knowing what it means, which is a shame, because it’s a genuinely simple concept once it’s properly explained, and understanding it actually clarifies why HBOT works the way it does.

What ATA Actually Stands For

ATA stands for atmospheres absolute, a unit of pressure. One ATA is the normal air pressure you experience every day at sea level, the ordinary weight of the atmosphere pressing down on you, which you don’t notice because you’re used to it and your body is built for it.

When we say a chamber runs at 1.3 ATA, that means the pressure inside is 1.3 times the normal pressure you experience standing outside right now. At 2.0 ATA, it’s double. It’s the same basic unit that divers use to describe pressure underwater, roughly every 10 metres you descend adds another ATA of pressure, which is a useful way to picture what these numbers actually feel like in practice.

Why Pressure Is the Whole Point

This is the part that actually matters for understanding HBOT. Under normal conditions, the oxygen in your blood is carried almost entirely by your red blood cells, which have a fixed capacity. Breathing more oxygen at normal pressure doesn’t change that much, your red blood cells are already close to full, and there’s a limit to how much more they can carry.

Increasing the surrounding pressure changes the equation entirely. There’s a principle in basic chemistry, sometimes called Henry’s Law, which states that the amount of a gas that dissolves into a liquid is directly related to the pressure of that gas around it. Put a liquid under higher pressure with oxygen, and more oxygen dissolves directly into it, beyond what would normally happen at standard pressure.

Applied to your body, that means increased pressure allows oxygen to dissolve directly into your blood plasma, not just your red blood cells, giving your body access to considerably more circulating oxygen than breathing normally would provide, even if you were breathing pure oxygen at standard atmospheric pressure.

Why Different Chambers Use Different Pressures

This is why our three tiers exist. A higher ATA means more oxygen dissolving into your plasma, and a stronger overall effect, but it also means a more intense session and a longer period of adjustment as the chamber pressurises and depressurises. Our Silver Tank, at a gentler 1.3 ATA, offers a genuine, real effect while remaining comfortable and accessible for someone trying HBOT for the first time. Gold and Platinum, at higher pressures, deliver a stronger effect suited to more demanding recovery needs, but ask a bit more of you in terms of adjustment and intensity.

Neither is more “correct” than the other. It’s a genuine trade-off between intensity and accessibility, which is exactly why matching the right chamber to your actual needs matters more than assuming higher pressure is automatically better.

Why You Feel Pressure in Your Ears

As the chamber pressurises, the pressure inside your ears needs to equalise with the pressure around you, the same sensation you get on a plane during takeoff or landing, or diving to the bottom of a swimming pool. This is completely normal and is why we talk you through simple techniques, swallowing, yawning, gently pinching your nose, to help your ears adjust comfortably as the pressure changes.

Why This Isn’t the Same as Just Breathing Oxygen

It’s worth being clear about a common misconception here. Simply breathing oxygen through a mask at normal atmospheric pressure doesn’t produce the same effect as HBOT, because without the increased pressure, there’s no meaningful additional dissolution of oxygen into your plasma. The pressure is doing the actual work here, not the oxygen alone. This is exactly why portable devices that don’t reach genuine hyperbaric pressure, or don’t use purified oxygen, can’t replicate what a proper clinical chamber achieves.

Making Sense of the Numbers

Next time you see 1.3, 1.5 or 2.0 ATA listed against one of our chambers, that number is directly telling you how much additional pressure, and therefore how much additional oxygen delivery, you’re actually getting.

It’s not a marketing figure, it’s the literal physical basis for why the treatment works at all.

If you’re deciding between our three chambers and want to understand which pressure level actually suits your goals, that’s exactly what your consultation is for.