Every documented fatal hyperbaric chamber fire in a 73-year analysis occurred in an oxygen-enriched atmosphere above 28% oxygen. That is the core answer: chambers rarely “explode” from mechanical failure. They fail through oxygen-fed fire that rapidly raises internal pressure, and less often through structural failure or over-pressurization. In ASME-certified clinical chambers these events are extremely rare. DIY and non-certified chambers carry far higher risk because they lack the redundant safety systems that prevent each failure mode.
Key Takeaways
- Every documented fatal hyperbaric fire occurred in an oxygen atmosphere above 28%; chambers on air below 23.5% oxygen had the only survivors, per Sheffield and Desautels (Undersea & Hyperbaric Medicine, 1997).1
- At 2.0 ATA, a 36-inch chamber door holds back over 14,850 pounds of outward force that releases instantly on catastrophic failure.
- In modern certified chambers, the odds of both redundant pressure-relief valves failing at once are under 1 in 10 million.
- NFPA 99 Chapter 14 requires rapid deluge fire suppression inside US hyperbaric facilities.3
- Two fatal US chamber fires in 2025 prompted an FDA safety communication on August 25, 2025.2
Why Is a Pressurized Hyperbaric Chamber Dangerous?
A hyperbaric chamber is a pressure vessel that holds gas above normal atmospheric pressure. At treatment pressures of 2.0 to 3.0 ATA (atmospheres absolute), its walls must contain large, continuous forces during every session, and the danger is a combination of that stored energy and the oxygen inside.
At 2.0 ATA, internal pressure sits about 14.7 PSI above ambient. On a 24-inch access port that works out to roughly 6,600 pounds of outward force on a single opening; a 36-inch door holds back over 14,850 pounds. If the vessel fails catastrophically, that energy releases in an instant: metal components become high-velocity projectiles and the pressure wave causes blast injuries to anyone nearby. The more common and more lethal path, though, is fire, because oxygen changes what “flammable” means.
What Are the Three Ways a Hyperbaric Chamber Can Fail?
Failure Modes: Certified vs DIY Chambers
| Failure mechanism | Trigger | Certified-chamber risk | DIY-chamber risk |
|---|---|---|---|
| Oxygen-fed fire | Spark or ignition source in an oxygen-enriched atmosphere | Low, controlled by item screening, grounding, and deluge suppression | High, no screening, grounding, or suppression |
| Structural / vessel failure | Weld fatigue, cracking, viewport or seal blowout, unrated materials | Extremely rare, ASME PVHO-1 proof-tests at 150% of operating pressure | High, PVC and non-engineered builds fragment under gas pressure |
| Over-pressurization | Relief-valve failure with no pressure release | Under 1 in 10 million (dual redundant relief valves) | High, often a single uncalibrated valve or none |
1. Oxygen-Fed Fire and Pressure Buildup (Most Common)
This is the most documented cause of catastrophic hyperbaric incidents. In an oxygen-enriched environment above 23.5% oxygen, materials that are normally hard to ignite become highly flammable. When a fire starts inside a pressurized chamber, combustion adds gas and heat, driving internal pressure up fast.1
The ignition sequence is rapid. In high-oxygen conditions at treatment pressure, a spark from static electricity, a phone battery, or friction from synthetic clothing can ignite materials almost instantly, and the fire then feeds on the oxygen-rich air. Sheffield and Desautels found that every documented fatal chamber fire from 1923 to 1996 happened in an enriched-oxygen atmosphere, which is why prohibited-item screening is a life-safety requirement, not paperwork.1 Documented ignition sources include smartphones and electronics, synthetic fabrics, petroleum-based skin and hair products, and static discharge from ungrounded equipment. Since 1980, items brought in by occupants have overtaken electrical malfunction as the leading ignition source.1 Our guide to hyperbaric chamber fire covers the ignition chain in more detail.
2. Structural Failure of the Pressure Vessel
Structural failure happens when walls, welds, viewports, or seals can no longer contain the internal pressure. It requires the vessel to be defective, damaged, or uncertified. ASME PVHO-1 (Pressure Vessels for Human Occupancy) exists to prevent exactly this, mandating specific material grades, qualified weld procedures, and proof testing at 150% of operating pressure.
Hard-shell metal chambers can in principle fail through weld fatigue, cracking, viewport blowout, or door-seal failure, turning metal into shrapnel. ASME PVHO-1 certification addresses each of these failure modes with documented engineering standards, and there is no record of an ASME PVHO-1 certified chamber suffering a catastrophic structural failure during patient treatment. That safety record rests on the certification requirements, not luck.
DIY PVC chambers are the most dangerous case. PVC under pneumatic (gas) pressure shatters into razor-sharp fragments instead of deforming like metal, and PVC is rated only for fluid pressure, never for gas. Building a pressure vessel from PVC pipe is building a fragmentation device, a point covered in our breakdown of the dangers of DIY hyperbaric chambers.
Soft-shell chambers typically fail by zipper rupture or fabric tear, causing rapid decompression rather than explosive fragmentation. That is still dangerous (rapid decompression can cause barotrauma), but far less lethal than a hard-shell rupture. Both barotrauma and decompression appear in our fuller rundown of hyperbaric chamber side effects.
3. Over-Pressurization From Safety-System Failure
Modern certified chambers use dual redundant pressure-relief valves, each independently able to prevent over-pressurization. The probability of both failing at once is calculated at under 1 in 10 million. DIY chambers usually have a single uncalibrated valve or none at all, so over-pressurization, which requires multiple independent failures in certified equipment, becomes far more plausible in uncertified builds.
What Does NFPA 99 Require to Prevent Fires?
NFPA 99 Chapter 14 sets the mandatory safety requirements for US hyperbaric facilities.3 The core fire and explosion controls include:
- Primary and secondary fire suppression systems.
- Rapid-activating deluge fire suppression (within seconds of detection).
- Fire-rated construction.
- Continuous oxygen monitoring in shared spaces.
- The ability to de-energize all circuitry entering the chamber in an emergency.
- Only 100% cotton or approved chamber garments.
- A designated Hyperbaric Safety Director for every program.
The Polish Hyperbaric Research review of chamber fires reaches the same conclusion from the incident record: ignition control and atmosphere management, not vessel strength, are what keep occupants safe.5
Why Are DIY Hyperbaric Chambers So Dangerous?
The FDA classifies hyperbaric chambers as Class II medical devices, and homemade chambers meet none of the applicable safety standards. Documented DIY risks include fire and explosion from uncontrolled oxygen meeting static or friction, structural failure of non-engineered materials, and CO2 buildup without proper ventilation. The UHMS explicitly warns consumers against soft-sided bag chambers and homemade pressure vessels.4
The legal exposure is real too: if someone is injured or killed in a homemade chamber, the builder can face criminal charges alongside civil liability.
What Happened in the 2025 Chamber Fires?
Two fatal US chamber fires in 2025 showed these risks are not theoretical, and both involved fire, not mechanical explosion in the everyday sense.2
January 31, 2025, Troy, Michigan: five-year-old Thomas Cooper died and his mother was injured when a chamber at the Oxford Center caught fire during treatment. Michigan’s Attorney General charged four people, the owner and three staff, with second-degree murder or involuntary manslaughter, alleging that manufacturer and NFPA safety protocols were disregarded.
2025, Arizona: a clinic owner died in a fire in a chamber at his own facility. Following these incidents, the FDA issued a Letter to Health Care Providers on August 25, 2025, urging strict adherence to fire-prevention protocols, grounding, staff training, and prohibited-item screening.2 For the broader mortality record, see our overview of how many people have died in a hyperbaric chamber.
How Can You Protect Yourself as a Patient?
- Choose UHMS-accredited facilities. Ask whether a facility holds UHMS Hyperbaric Facility Accreditation before scheduling.
- Verify staff credentials. CHT or CHRN certification signals adherence to safety training standards.
- Follow prohibited-item protocols without exception. These directly prevent fires. A facility that is casual about screening is not operating safely.
- Arrive product-free for clinical sessions. No deodorant, perfume, or petroleum-based products before a monoplace oxygen chamber.
- Never bring electronics or synthetic clothing into a 100% oxygen atmosphere. This applies at a clinic and at home with an oxygen concentrator.
Sources
- Sheffield PJ, Desautels DA. “Hyperbaric and hypobaric chamber fires: a 73-year analysis.” Undersea & Hyperbaric Medicine, 1997;24(3):153-164. PMID: 9308138
- US Food and Drug Administration. “Follow Instructions for Safe Use of Hyperbaric Oxygen Therapy Devices: Letter to Health Care Providers.” August 25, 2025. fda.gov
- National Fire Protection Association. “NFPA 99 Health Care Facilities Code, Chapter 14 (Hyperbaric Facilities).” 2024 Edition. nfpa.org
- Undersea and Hyperbaric Medical Society. “Consumer Warning: The Dangers of Soft-Sided Bag Chambers.” uhms.org
- Zielinski E, et al. “Fire in the Hyperbaric Chamber: Review of the Literature.” Polish Hyperbaric Research, 2023. doi:10.2478/phr-2023-0020
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.
