At 1.3 ATA with ambient air, arterial oxygen reaches approximately 230 mmHg. At 2.0 ATA with 100% oxygen, it reaches approximately 1,800 mmHg. That is not a small difference. It is an eightfold difference.1 And yet soft chamber providers routinely market their 1.3 ATA devices for neurological conditions like TBI, long COVID brain fog, and post-stroke recovery, citing studies that used hard chambers at 1.5 to 2.0 ATA. This is a problem.
The Math That Soft Chamber Marketing Ignores
Hyperbaric oxygen therapy works by dissolving oxygen directly into blood plasma under pressure. The amount of dissolved oxygen follows Henry’s Law: the concentration of a gas dissolved in a liquid is proportional to the partial pressure of that gas above the liquid. Here is what that means in practice:1
| Setting | Pressure | Oxygen % | Approx. Arterial pO2 |
|---|---|---|---|
| Normal breathing at sea level | 1.0 ATA | 21% | ~100 mmHg |
| Soft chamber with concentrator | 1.3 ATA | ~24% | ~230 mmHg |
| Soft chamber with O2 mask | 1.3 ATA | ~90% | ~600 mmHg |
| Hard chamber (Harch protocol) | 1.5 ATA | 100% | ~1,100 mmHg |
| Hard chamber (Efrati protocol) | 2.0 ATA | 100% | ~1,800 mmHg |
| Hard chamber (wound care) | 2.4 ATA | 100% | ~2,100 mmHg |
“A standard soft chamber at 1.3 ATA with ambient air delivers a partial pressure of oxygen roughly equal to breathing slightly enriched air at sea level. It is better than normal breathing. It is not in the same category as medical HBOT.”1
Difference in arterial oxygen between soft chamber (1.3 ATA) and hard chamber (2.0 ATA with 100% O2)1
The Studies Soft Chamber Marketers Cite
When soft chamber providers market their devices for neurological conditions, they typically reference three bodies of research:
- The Tel Aviv long COVID RCT (Zilberman-Itskovich et al., 2022, published in Scientific Reports) — This study used 2.0 ATA with 100% oxygen in a multiplace hard chamber. Not 1.3 ATA. Not a soft chamber.2
- The Efrati aging study (Efrati et al., 2020, published in Aging) — This study used 2.0 ATA with 100% oxygen and demonstrated telomere lengthening and senescent cell reduction. Hard chamber only.
- Harch’s TBI work — Even the Harch protocol, which uses the lowest pressure of any major HBOT research program, operates at 1.5 ATA with 100% oxygen. That is still meaningfully higher than what a soft chamber achieves even with a concentrator.3
None of the major neurological HBOT studies used 1.3 ATA soft chambers. A 2023 tissue oxygenation study found that levels at 1.4 ATA were approximately half those achieved at 2.0 ATA in chronic ulcer patients.4 When a soft chamber provider says “research shows HBOT helps with brain injuries” while selling you a 1.3 ATA device, they are referencing research conducted with fundamentally different equipment at fundamentally different pressures.
The Bacteriostatic Threshold
Oxygen becomes bacteriostatic — capable of suppressing bacterial and fungal growth — only above 1.5 ATA.5 This is why soft chambers cannot be used to treat wound infections, gas gangrene, or necrotizing soft tissue infections. The UHMS issued a formal consumer warning about soft-sided bag chambers, stating they do not meet clinical HBOT standards.5
“Bacterial growth suppression requires pressure above 1.5 ATA — a threshold that soft-shell chambers physically cannot reach.”5
What 1.3 ATA Can and Cannot Do
This is not an argument that soft chambers are useless. It is an argument that they are being sold for things they were not designed and have not been proven to do.
What soft chambers at 1.3 ATA may reasonably help with:
- General wellness and mild recovery
- Subjective improvements in energy and sleep (reported by users, limited controlled data)
- Altitude sickness (the only FDA-cleared indication for soft chambers)
- Light exercise recovery for athletes (anecdotal, minimal controlled evidence)
What soft chambers at 1.3 ATA have NOT been shown to help with:
- Traumatic brain injury recovery
- Long COVID cognitive symptoms
- Post-stroke neuroplasticity
- Telomere lengthening or biological age reversal
- Any of the 14 FDA-cleared indications for medical HBOT
The FDA is explicit about this. Soft-sided chambers are FDA-cleared only for acute mountain sickness. They are not cleared for any of the 14 medical indications that apply to hard chamber HBOT.6
Randomized controlled trials directly comparing soft-shell vs hard-shell outcomes for any neurological condition7
Why This Matters for Patients
A patient with long COVID brain fog who spends $5,000 on 40 soft chamber sessions at 1.3 ATA and sees no improvement may conclude that “HBOT doesn’t work.” But what they actually received was not the treatment that produced positive results in the clinical trials. They received a lower-pressure, lower-oxygen intervention that has never been tested for their condition in a controlled study.
This is not just a theoretical concern. In HBOT patient communities, one of the most common frustrations is: “I tried HBOT and it didn’t help.” When you dig into the details, a significant percentage of these patients were treated in soft chambers at 1.3 ATA for conditions where only hard chamber protocols have evidence. They didn’t fail HBOT. They never received HBOT as studied.
The Counterargument: Gene Expression vs Dissolved Oxygen
Proponents of soft chamber therapy argue that the therapeutic mechanism of HBOT is not solely about dissolved oxygen levels. They point to research suggesting that even mild pressure increases can trigger beneficial gene expression changes, activate hypoxia-inducible factor (HIF-1) pathways, and stimulate anti-inflammatory responses at pressures below 1.5 ATA.
This argument has some biological plausibility. However, the evidence is not strong enough to support the marketing claims being made. The studies at 1.3 ATA are mostly small, uncontrolled, and have not been replicated. The robust RCTs with large effect sizes are all at 1.5+ ATA with 100% oxygen. Until there are equivalence trials directly comparing 1.3 ATA soft chamber outcomes to 2.0 ATA hard chamber outcomes for neurological conditions, claiming equivalence is misleading.
What Buyers Should Do
- If you are treating a specific neurological condition (TBI, long COVID, stroke, cognitive decline): seek a clinic with a hard chamber capable of reaching the ATA used in the relevant clinical trials. For most neurological conditions, that means 1.5 to 2.0 ATA with 100% oxygen.
- If you are buying a home chamber for general wellness: a soft chamber at 1.3 ATA is a reasonable option, provided you understand and accept its limitations. Do not expect it to replicate the results of hard chamber clinical trials.
- If a clinic or chamber manufacturer cites a study: check what pressure and oxygen concentration the study used. If it was 2.0 ATA in a hard chamber and they are selling you 1.3 ATA in a soft chamber, they are misleading you.
- Use the BARIC Score to evaluate any clinic before committing. The “A” in BARIC stands for ATA Range, and it is there specifically because this mismatch is one of the most common ways patients get shortchanged.
Frequently Asked Questions
Are you saying soft chambers are a scam?
No. Soft chambers have a legitimate place in general wellness and may provide modest benefits for recovery and energy. The problem is marketing them for conditions where only hard chamber HBOT has evidence. The device is not a scam. The marketing around it often is.
Why do so many people say they feel better after soft chamber sessions?
Several possible explanations: placebo effect (which is real and measurable), genuine mild oxygenation benefit, the relaxation of lying still for 60-90 minutes, or a real but modest effect that falls short of what a hard chamber would deliver. Subjective improvement is valid. But subjective improvement in an uncontrolled setting does not equal the clinical outcomes reported in controlled trials at higher pressures.
Can I use a soft chamber with a separate oxygen concentrator to get closer to hard chamber results?
Adding an oxygen concentrator (delivering ~90% O2) to a soft chamber at 1.3 ATA increases the partial pressure of oxygen meaningfully — but still below the 1.5 ATA achieved in the Harch protocol. It is a reasonable middle ground for home users, but it does not replicate hard chamber clinical protocols, and using supplemental oxygen in a soft chamber introduces additional fire safety considerations.
- Burman F. “Low-pressure fabric hyperbaric chambers.” South African Medical Journal. 2019;109(4). PMID: 31084683. doi:10.7196/SAMJ.2019.v109i4.13580
- Zilberman-Itskovich S, et al. “Hyperbaric oxygen therapy improves neurocognitive functions and symptoms of post-COVID condition.” Scientific Reports. 2022;12:11252.
- Harch PG. “Systematic Review and Dosage Analysis: HBOT Efficacy in Mild TBI Persistent Postconcussion Syndrome.” Frontiers in Neurology. 2022. PMID: 35370898
- Sack RA et al. “Transcutaneous oximetry values in chronic ulcer patients at 1.4 ATA vs 2 ATA.” Undersea and Hyperbaric Medicine. 2023. PMID: 38615347
- UHMS Consumer Warning. “The Dangers of Soft-Sided Bag Chambers.” uhms.org/pressure-other-articles/1542-consumer-warning.html
- FDA. “Hyperbaric Oxygen Therapy: Get the Facts.” fda.gov/consumers/consumer-updates/hyperbaric-oxygen-therapy-get-facts
- PMC. “A general overview on the hyperbaric oxygen therapy.” PMC8465921. 2021.
- Efrati S, et al. “Hyperbaric oxygen can diminish fibromyalgia syndrome.” Aging. 2020.
- Efrati S, et al. “Hyperbaric oxygen therapy increases telomere length and decreases immunosenescence in isolated blood cells.” Aging. 2020.
Medical Disclaimer
The content on BaricBoost.com is for informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
Author
Seph Fontane Pennock is the founder of BaricBoost.com and Regenerated.com, a clinic directory for regenerative medicine serving 10,000+ providers across the United States. He previously built and sold PositivePsychology.com, which grew to 19 million users and became the largest evidence-based positive psychology resource on the web. Seph brings direct experience as an HBOT patient, having completed protocols at clinics across three continents while navigating mold illness, systemic inflammation, and autoimmune conditions. His treatment journey includes hyperbaric oxygen therapy, peptide protocols, NAD+ therapy, and consultations with specialists from Dubai to Cape Town to Mexico. This combination of entrepreneurial track record and lived patient experience shapes everything published on BaricBoost.com. Every article is grounded in peer-reviewed research, informed by real clinical encounters, and written for patients making high-stakes treatment decisions. Seph's focus is on bringing transparency, scientific rigor, and practical guidance to the hyperbaric oxygen therapy space.
