Compare
Mild Hyperbaric (1.3 ATA) vs. Medical-Grade HBOT
Mild hyperbaric therapy and medical-grade HBOT are different oxygen doses, not two strengths of one treatment. Mild chambers run at about 1.3 ATA, usually on room air, and are FDA-cleared only for acute mountain sickness. Recognized medical uses call for near-100% oxygen at 2.0 ATA or more.
Definitions
What Counts as Hyperbaric Oxygen Therapy
The Undersea and Hyperbaric Medical Society (UHMS) is the main professional body for hyperbaric medicine. Its definition has three parts. Hyperbaric oxygen therapy means:
- breathing near-100% oxygen,
- while fully enclosed in a chamber,
- at a pressure of at least 1.4 atmospheres absolute (ATA).
On top of that minimum, every indication UHMS recognizes uses 2.0 ATA or more.
"Mild hyperbaric therapy," sometimes shortened to mHBOT, usually means a low-pressure fabric chamber running at about 1.3 ATA, most often on room air. Because it falls below 1.4 ATA and usually does not use near-100% oxygen, it does not meet the UHMS definition of HBOT. ATA simply means total pressure: 1.0 ATA is normal air pressure at sea level. Our guide to how pressure dissolves oxygen into plasma explains the science.
The Numbers
The Dose Difference in Numbers
The simplest way to compare oxygen dose is the pressure of oxygen you breathe in. Multiply the chamber pressure by the share of oxygen in the gas. Air is about 21% oxygen; medical HBOT uses near-100% oxygen.
| Setting | Pressure | Gas | Inspired oxygen pressure (approx.) | Compared with sea-level air |
|---|---|---|---|---|
| Everyday air at sea level | 1.0 ATA | Air (21% O₂) | 0.21 ATA | Baseline |
| Mild chamber | 1.3 ATA | Air (21% O₂) | 0.27 ATA | About 1.3 times |
| Medical HBOT | 2.0 ATA | Near-100% O₂ | 2.0 ATA | About 9.5 times |
| Medical HBOT (common wound protocol) | 2.4 ATA | Near-100% O₂ | 2.4 ATA | About 11 times |
That is the heart of the difference. A mild chamber on air raises the oxygen you breathe by roughly 30%. A medical chamber at 2.0 to 2.4 ATA on pure oxygen raises it about ten-fold. At those higher levels, much more oxygen dissolves directly into the plasma, the liquid part of your blood, and can reach tissue with poor blood supply.
The effects medicine has studied for cleared indications, such as supporting new blood vessel growth in poorly healing tissue and helping white blood cells fight infection, depend on that dose. Some mild-chamber setups add concentrator oxygen by mask, which raises the number, but still does not match near-100% oxygen at 2.0 ATA or more.
Clinical Practice
Which Pressures Recognized Indications Use
Your physician sets your pressure and session length. As a general guide, these are the ranges typically used for recognized indications, and the pressures used in some of the best-known trials.
| Indication | Typical pressure | Notes |
|---|---|---|
| Selected diabetic foot ulcers and problem wounds | 2.0–2.5 ATA | The Löndahl 2010 trial used 2.5 ATA for 85 minutes. |
| Delayed radiation injury (soft tissue and bone) | 2.0–2.4 ATA | The RICH-ART trial for radiation cystitis used 2.4 ATA. |
| Compromised skin grafts and flaps | 2.0–2.5 ATA | Used around surgery to support at-risk tissue. |
| Refractory osteomyelitis | 2.0–2.5 ATA | Used alongside surgery and antibiotics. |
| Sudden sensorineural hearing loss | 2.0–2.5 ATA | Combined with steroids, ideally within two weeks of onset. |
| Emergencies: carbon monoxide poisoning, decompression sickness, gas embolism | Up to 2.8–3.0 ATA | Hospital-based chambers. Call 911. |
A typical elective session lasts about 90 to 120 minutes including pressurization and depressurization, and a course is often 20 to 40 sessions. None of these recognized protocols uses 1.3 ATA on air. See the recognized indications or read about diabetic foot ulcer protocols in more detail.
The Honest Answer
Is 1.3 ATA Hyperbaric Effective?
For any FDA-cleared or UHMS-recognized indication, no. 1.3 ATA does not reach the 1.4 ATA minimum in the HBOT definition, let alone the 2.0 ATA or more that recognized protocols use. No recognized indication is approved at that dose.
Some small studies have tested pressures between 1.3 and 1.5 ATA for conditions that are not FDA-cleared. Results have been mixed. Several of these studies had design problems, including the difficulty of building a true placebo: even a "sham" session at slightly raised pressure changes the oxygen a person breathes, which makes results hard to interpret.
UHMS does not recommend mild hyperbaric therapy for any medical purpose other than acute mountain sickness. If you have been offered mild sessions for a medical condition, it is reasonable to ask what evidence supports that use at that pressure.
Regulation
FDA Clearance and What "Off-Label" Means Here
The FDA clears medical devices for specific intended uses.
- Low-pressure fabric chambers are FDA-cleared for acute mountain sickness.
- Medical hyperbaric chambers are FDA-cleared for a defined list of uses, including selected diabetic wounds, delayed radiation injury, compromised grafts and flaps, refractory bone infection, sudden hearing loss, severe burns and several emergencies.
A device can be legally sold for its cleared use and then used for something else. That is "off-label" use. It isn't automatically illegal, but it means the use has not been cleared, and the person paying for it carries the uncertainty about whether it helps. "FDA-cleared chamber" describes a device and its intended use. It does not mean every use of that chamber has been shown to work. For a closer look at construction differences, read hard-shell vs. soft-shell construction.
Safety
Safety at Each Pressure
A higher dose of oxygen brings more potential benefit for the right condition, and more responsibility. That is why medical protocols are set by a physician and time-limited.
Medical-grade HBOT
The most common side effect is pressure on the ears (middle-ear barotrauma), similar to what you feel on a plane. Temporary nearsightedness (distance vision becoming blurrier) can develop over a long course and usually improves within weeks to months after treatment ends. Oxygen toxicity is dose-related; a seizure is rare, occurring in roughly 1 in 5,000 to 10,000 treatments. Confinement anxiety and fatigue can also happen. Screening before treatment helps manage these risks.
Mild chambers
Lower pressure means ear pressure can still occur, though the oxygen-related risks are lower when breathing air. Adding concentrator oxygen to a fabric enclosure creates fire-safety concerns. Screening for conditions like an untreated collapsed lung matters at any pressure, and many mild chamber settings do not include physician screening. For home use in particular, see home chambers vs. clinic care.
At Generations Wellness
What Generations Wellness Delivers
We provide HBOT in hard-shell monoplace chambers. You breathe medical-grade oxygen at a pressure prescribed by the physician for your condition. Care is directed by Dr. Rajwinder Singh Bahia, MD, and every course starts with a physician assessment of whether HBOT is appropriate for you, including an honest answer when it isn't.
To ask what pressure you would be treated at, call (369) 222-0979, or read about our treatment standards.
Important
A physician assessment is required before beginning HBOT at Generations Wellness. HBOT complements, and never replaces, the treatment prescribed by your doctors.
Questions
Mild vs. Medical-Grade HBOT: Frequently Asked Questions
Is mild hyperbaric oxygen therapy (1.3 ATA) the same as medical HBOT?
No. UHMS defines HBOT as at least 1.4 ATA on near-100% oxygen, and every recognized indication uses at least 2.0 ATA. 1.3 ATA on air raises the oxygen you breathe only modestly.
What does ATA mean?
Atmospheres absolute, a measure of total pressure. 1.0 ATA is sea level; medical HBOT commonly uses about 2.0 to 2.5 ATA, and emergency protocols go up to about 3.0.
Is 1.3 ATA hyperbaric effective?
Not for any FDA-cleared or UHMS-recognized indication. UHMS does not recommend mild hyperbaric therapy for medical purposes other than acute mountain sickness.
What pressure is used for wound healing?
Typically 2.0 to 2.5 ATA on near-100% oxygen for about 90 minutes of treatment time. Your physician sets the exact protocol.
Sources
- Undersea and Hyperbaric Medical Society. Position Statement on Low-Pressure Fabric Hyperbaric Chambers. uhms.org
- Indications for oxygen therapy and the Undersea and Hyperbaric Medical Society (review, 2023). pmc.ncbi.nlm.nih.gov
- Undersea and Hyperbaric Medical Society. Hyperbaric Oxygen Therapy Indications. uhms.org
- Löndahl M, et al. Hyperbaric oxygen therapy facilitates healing of chronic foot ulcers in patients with diabetes. Diabetes Care, 2010. pmc.ncbi.nlm.nih.gov
- Oscarsson N, et al. Radiation-induced cystitis treated with hyperbaric oxygen therapy (RICH-ART). Lancet Oncology, 2019. pubmed.ncbi.nlm.nih.gov
- StatPearls. Hyperbaric Treatment of Chronic Refractory Osteomyelitis (session length and course). ncbi.nlm.nih.gov
- U.S. Food and Drug Administration. Hyperbaric Oxygen Therapy: Get the Facts. fda.gov
- StatPearls. Hyperbaric Complications. ncbi.nlm.nih.gov
This page is educational and not medical advice. A physician assessment is required before HBOT. See our full medical disclaimer.
Your Next Step
Begin With a Physician Assessment
Every course starts with an honest conversation and a physician assessment. No pressure, no obligation.
Prefer to talk? (369) 222-0979