Soft Shell vs Hard Shell Hyperbaric Chamber: How to Choose

The Short Answer

If a doctor has referred you for hyperbaric oxygen therapy (HBOT) for a medical condition, you need a hard shell chamber. Every indication approved by the Undersea and Hyperbaric Medical Society (UHMS) requires near-100% oxygen at 2.0 atmospheres absolute (ATA) or more, and soft chambers are not designed to go above 1.4 ATA.

A soft shell chamber is a low-pressure, air-filled fabric chamber. In the US its only FDA-cleared use is acute mountain sickness. People buy or book soft chambers for wellness and recovery, but the UHMS says it knows of no reliable clinical evidence that pressures below 1.4 ATA have a therapeutic effect.

This post is a decision guide: what to check before you book a session or buy a chamber. For a plain side-by-side explainer of the two designs, see our page on hard-shell vs soft-shell chambers.

Soft Shell vs Hard Shell Hyperbaric Chamber: Comparison Table

Decision factor	Hard shell chamber	Soft shell chamber
Construction	Rigid pressure vessel. Monoplace (one person) or multiplace (several people)	Inflatable fabric enclosure with an air compressor
Treatment pressure	Typically 2 to 3 ATA in clinical use	Less than 1.4 ATA; one cleared model has relief valves set at 4 psi, about 1.3 ATA
Breathing gas	Near-100% oxygen, chamber-filled or by mask or hood	Air only. The FDA has not cleared soft chambers for use with oxygen tanks or concentrators
FDA-cleared uses (US)	A defined list of conditions, from decompression sickness to diabetic foot ulcers	Acute mountain sickness only
Counts as HBOT under the UHMS definition	Yes	No
Who supervises	A physician trained in hyperbaric medicine, with trained chamber operators	Prescription device whose cleared places of use include the home
Building and fire standards	Room and installation must meet NFPA 99 Chapter 14 in the US; multiplace chambers in Europe must comply with EN 14931	The UHMS says hyperbaric chambers should meet the same codes; it does not endorse in-home therapy
Insurance (US Medicare)	Covered for conditions listed in national coverage determination 20.29	Wellness use is not on that list

Start With Why You Want a Chamber

You have a diagnosed condition

Choose a clinical hard shell facility. The FDA lists the conditions hyperbaric chambers are cleared for, including decompression sickness, carbon monoxide poisoning, radiation injury, compromised skin grafts and non-healing diabetic foot ulcers. The FDA also advises patients to go to a hospital or facility that is accredited by the UHMS.

For emergencies such as carbon monoxide poisoning or decompression illness, do not look for a chamber yourself. Call your local emergency number. Divers can also call the DAN Emergency Hotline on +1-919-684-9111 once emergency services are contacted.

You are curious about wellness or recovery

Here the choice is less about the chamber and more about what you expect from it. The UHMS position statement says mild hyperbaric exposure with air "will deliver no more oxygen to the body than breathing oxygen by mask at sea-level pressure." If a provider claims a soft chamber session is equivalent to clinical HBOT, that claim is not supported. Our comparison of mild hyperbaric therapy and medical HBOT explains the oxygen numbers.

You are thinking of buying a home chamber

Buying is where most of the risk sits, because nobody supervises the sessions. Use the checklist below before you pay.

Buyer Checklist for a Soft Shell Chamber

Check the FDA clearance. Hyperbaric chambers are Class II medical devices cleared through the 510(k) process. The FDA says cleared devices can be found by searching product code CBF in its 510(k) database. Ask the seller for the 510(k) number and read the cleared "indications for use".
Expect a prescription requirement. The 510(k) summary for the Flexi-Lite soft chamber states that federal law restricts the device to sale by or on the order of a physician.
Never add oxygen. The FDA has not cleared these bags for use with oxygen tanks or oxygen concentrators, and warns that people who turn them into homemade HBOT devices risk fire and suffocation.
Look at the pressure rating. The Flexi-Lite summary describes a chamber for pressures under 5 psi, with relief valves set at 4 psi. A seller advertising much higher pressure from a fabric chamber is selling something outside that cleared design.
Know the medical position. The UHMS does not recommend mild hyperbaric therapy for any medical purpose other than acute mountain sickness, and does not endorse in-home hyperbaric therapy.
Ask your doctor first if you have ear, sinus or lung problems. Pressure changes affect air spaces in the body even at low pressure. In a 2001 trial, 15 of 54 children breathing air at 1.3 ATA had ear problems.

What Patients Should Know About Hard Shell Chambers

The US fire code for health care facilities, NFPA 99, classes human hyperbaric chambers by occupancy: Class A for multiple occupants and Class B for a single occupant.

Monoplace (Class B) chambers are typically compressed with oxygen. The UHMS says patients in monoplace chambers using 100% oxygen should wear grounding straps to prevent static discharge.
Multiplace (Class A) chambers are pressurised with air while patients breathe oxygen by mask or hood. A staff member can be inside with you, which helps if you need monitoring.
A 2017 review notes that patients who cannot tolerate a monoplace chamber because of confinement anxiety may be referred to a multiplace chamber.

The UHMS lists what a safe hard shell service looks like: a physician evaluation and prescription, FDA-cleared chambers, daily safety inspections, trained and credentialed staff, no flammable or static-generating items, continuous monitoring and regular emergency drills. See how to choose an HBOT clinic for the full checklist.

Is a Soft Shell or Hard Shell Chamber Safer?

Neither type is risk-free, and the risks differ.

Fire risk depends mainly on oxygen. An analysis of chamber fires from 1923 to 1996 found that every fatal fire happened in an oxygen-enriched atmosphere (more than 28% oxygen) with plenty of burnable material. Chambers pressurised with air (under 23.5% oxygen) had the only survivors. A soft chamber used as designed, with air, avoids that condition. Adding an oxygen concentrator removes that margin.

Hard shell chambers use pure oxygen, so they rely on procedures. In August 2025 the FDA reminded facilities that it is aware of fires with HBOT devices that caused serious injuries and deaths, and asked them to follow manufacturer instructions, use grounding equipment, keep prohibited items out and dress patients in materials such as cotton. When used for cleared indications, the FDA describes HBOT as generally safe, with serious complications being rare.

Pressure side effects apply to both. Ear and sinus pain are the most common. With repeated clinical sessions at 2.0 ATA or more, temporary short-sightedness is also common. For the fire-safety rules patients follow, see our guide to phones and batteries in hyperbaric chambers.

What About Cost?

Prices vary too widely by country and provider to quote a reliable range, so compare actual quotes. Two points hold in general:

In the US, Medicare covers HBOT only for the conditions in its national coverage determination 20.29, administered in a chamber. Wellness and recovery uses are not on that list, so expect to pay yourself.
A home soft chamber is a one-off purchase, but it buys a low-pressure air exposure, not medical HBOT. It is not a cheaper substitute for a prescribed course of treatment.

How Common Is Each Type?

Hard shell chambers dominate the facilities listed on hyperbaric.app. Of the listings that record a shell type, 1,170 offer hard shell chambers and 149 offer soft shell chambers (as of 14 September 2026). The live numbers are on our HBOT statistics page.

To compare providers near you and filter by chamber type, start with HBOT clinics near me.

Sources

Undersea and Hyperbaric Medical Society, UHMS Position Statement: Low-Pressure Fabric Hyperbaric Chambers (created 2017, revised 2018). Undersea Hyperb Med. 2018;45(4):486-487.
Undersea and Hyperbaric Medical Society, Ten Guidelines for Patients and Referring Physicians in Selecting Safe Hyperbaric Oxygen Treatments (April 2025).
U.S. Food and Drug Administration, 510(k) summary K051759: Flexi-Lite Hyperbaric Chamber (2005).
U.S. Food and Drug Administration, Hyperbaric Oxygen Therapy: Get the Facts (consumer update, content current as of July 2021; archived copy).
U.S. Food and Drug Administration, Follow Instructions for Safe Use of Hyperbaric Oxygen Therapy Devices: Letter to Health Care Providers (25 August 2025).
Centers for Medicare and Medicaid Services, National Coverage Determination 20.29: Hyperbaric Oxygen Therapy.
National Fire Protection Association, NFPA 99: Health Care Facilities Code, Chapter 14 Hyperbaric Facilities.
Sheffield PJ, Desautels DA. Hyperbaric and hypobaric chamber fires: a 73-year analysis. Undersea Hyperb Med. 1997;24(3):153-164.
Heyboer M 3rd, Sharma D, Santiago W, McCulloch N. Hyperbaric Oxygen Therapy: Side Effects Defined and Quantified. Adv Wound Care. 2017;6(6):210-224.
Collet JP, Vanasse M, Marois P, et al. Hyperbaric oxygen for children with cerebral palsy: a randomised multicentre trial. Lancet. 2001;357(9256):582-586.
Kot J, Desola J, Lind F, et al. A European code of good practice for hyperbaric oxygen therapy: Review 2022. Diving Hyperb Med. 2023;53(4 Suppl):1-17.
Divers Alert Network, Emergency Assistance

This article is for information only and is not medical advice. Whether HBOT is appropriate for you, and in which type of chamber, should be decided with a qualified physician.