Are Cell Phones and Lithium Batteries Safe in Hyperbaric Chambers?

The Question Every HBOT Patient Asks

Can you take your phone into a hyperbaric chamber? In a medical hyperbaric oxygen therapy (HBOT) chamber, the answer is almost always no. Safety guidance from the Undersea and Hyperbaric Medical Society (UHMS) says any electrical or static-generating devices must be excluded from the chamber, and staff will ask you to leave your phone outside.

It is a fair question. A modern phone rarely catches fire, but inside a chamber you sit in pressurised, oxygen-rich gas, in a space you cannot leave quickly. Here is what the codes, safety engineers and fire records say.

Why Oxygen Changes Everything

Normal air is 21% oxygen. Safety engineers treat an atmosphere above about 23.5% oxygen as oxygen-enriched. According to hyperbaric safety engineer Francois Burman, a higher oxygen pressure lowers the ignition temperature of materials, increases the heat of a fire and speeds up flame spread.

Chamber fire history shows how much the oxygen level matters. A review of hyperbaric and hypobaric chamber fires from 1923 to 1996 counted 77 deaths in 35 hyperbaric chamber fires. Every fatal chamber fire happened in an atmosphere with more than 28% oxygen and plenty of burnable material. Chambers pressurised with air, under 23.5% oxygen, had the only survivors.

That is why the two main chamber types carry different levels of risk:

Hard-shell medical chambers. Monoplace chambers are typically compressed with oxygen, so the whole space around you is close to 100% oxygen. Multiplace chambers are compressed with air while you breathe oxygen through a mask or hood.
Soft-shell mild chambers. These are designed to be pressurised with air only, below 1.4 ATA. The FDA has not cleared them for use with oxygen tanks or oxygen concentrators, and warns that turning them into homemade oxygen chambers can pose a risk of fire and suffocation.

The Actual Risk Level

Lithium-ion battery fires make headlines, but they are rare for any single device. In his risk assessment for hyperbaric use, Burman notes that an estimated five billion people carry a mobile device with a rechargeable lithium-ion battery, and rates the probability of a battery mishap in everyday life as "unlikely".

Put the same battery inside a hyperbaric chamber and his assessment changes on every count:

Exposure is continuous for the whole time the device is in the chamber.
Severity rises, because a fire in an oxygen-rich, hard-to-escape space is far more dangerous.
Probability rises, because pressure changes could affect the thin separator inside the battery.

The fire record points the same way. The 73-year review found that since 1980, chamber fires have been caused primarily by prohibited ignition sources that an occupant carried into the chamber. A small chance of failure is not acceptable when the item serves no purpose inside.

What Past Chamber Fires Show

Fatal chamber fires are rare, but three US cases from news reports show what can go wrong:

Florida, May 2009. A fire inside a chamber at a hyperbaric centre in Lauderdale-by-the-Sea killed a 62-year-old woman and her 4-year-old grandson, who had travelled from Italy for his treatment.
Florida, February 2012. An apparent spark in an equine hyperbaric chamber at a horse rehabilitation centre in Ocala caused an explosion that killed a 28-year-old worker and a horse. The State Fire Marshal's Office investigated.
Michigan, January 2025. A 5-year-old boy died when the chamber he was being treated in caught fire at the Oxford Center in Troy. Four staff members were charged. In February 2026 a judge ordered all four to stand trial, citing evidence that patients were not allowed to wear grounding wrist straps and that physical safety checks before treatment were lacking. Lawyers for some of the defendants have called it an accident. The charges have not been proven, and at the time of that ruling no trial date had been set.

None of these fires has been publicly attributed to a phone, but they show what matters: oxygen, ignition sources, static control and pre-session checks. After the Michigan death, the UHMS published safety guidelines for patients, and in August 2025 the FDA reminded facilities to follow manufacturer instructions, use grounding equipment and keep prohibited items, "including electrical or static devices", out of chambers.

What the Rules Say About Batteries

The US fire code for health care facilities, NFPA 99, has a chapter dedicated to hyperbaric facilities (Chapter 14). As summarised by Burman:

The 2012 edition said lithium batteries "shall be prohibited in the chamber during chamber operations", unless the product had been accepted or listed for hyperbaric use by the manufacturer or a nationally recognised testing agency.
The 2018 edition replaced it with rules for battery-operated devices in multiplace (Class A) chambers: batteries fully enclosed, sealed and undamaged by pressure, never charged or changed in the chamber, and equipment rated no higher than 12 V and 48 W.
It set no specific battery rules for monoplace (Class B) chambers, but Burman notes the code's intent is to keep power sources outside them.

In Europe, the European Code of Good Practice for HBOT lists "electrical equipment" and "batteries with unprotected leads" among prohibited materials.

These rules describe equipment a facility has assessed for use under pressure. For patients, the UHMS guidance is simpler: keep electrical devices out.

Risk Factors That Matter

If a facility ever does approve a battery-powered device, these factors raise the risk, based on Burman's review:

Charging. The period of highest risk is recharging. Nothing should ever be charged under pressure.
Physical damage. Dropping a device can rupture the internal separator and cause a short circuit.
Swelling or leaks. A failing lithium-ion battery may bulge, hiss or leak electrolyte.
Heat. Lithium-ion batteries can rupture, ignite or explode above 60°C (140°F).
Non-original parts. Aftermarket chargers and replacement batteries may lack the manufacturer's protection against overcharging.

Airplane mode does not remove the battery, and a well-known brand does not make a phone hyperbaric-rated. The only relevant question is whether the facility's safety coordinator has assessed and approved that specific device.

What's Actually More Dangerous Than Your Phone

Your clothes and the products on your skin and hair can matter as much as a battery.

Fabric. The UHMS says 100% cotton garments (and some cotton-polyester blends) are acceptable, and silk, wool and synthetic materials should stay out unless approved. The FDA notes that wool and synthetic fabrics may produce more static electricity.
Grounding. In monoplace chambers using 100% oxygen, the UHMS says patients should wear grounding straps to eliminate static discharge.
Flammable products. The European code lists aerosols, aftershave, alcohol, petroleum-based lubricants and grease, lighters and matches among prohibited materials. The UHMS says products that produce flammable vapours must be kept out of oxygen-enriched environments.

This is why clinics usually ask you to change into facility-issued cotton clothing and remove lotions, hair products and makeup.

Practical Safety Guidelines

Before your session:

Ask for the clinic's written list of prohibited items, and follow it even if another clinic allowed something.
Leave your phone, smartwatch, earbuds and other battery-powered devices in the locker.
Change into the cotton clothing the clinic provides, and skip lotions, oils, hairspray and perfume.
Tell staff about any implanted or medical device so they can check it.

During your session:

Never charge any device in or next to the chamber.
If you notice heat, smoke or a burning smell, alert the operator immediately.

Never bring: vapes or e-cigarettes, lighters or matches, hand warmers, power banks or spare batteries, or any device that is damaged or has a swollen battery.

What About Mild Soft-Shell Chambers?

Soft chambers used as designed, with air at low pressure, do not create an oxygen-enriched atmosphere, and the fire record shows air-filled chambers are far more survivable. Operators set their own rules on devices. The picture changes completely if an oxygen concentrator is added, which the FDA has not cleared. Whatever the operator allows, never add oxygen and never charge a device inside. For the wider trade-offs, see soft shell vs hard shell hyperbaric chambers or our chamber types explainer.

What Clinics Should Provide

In line with the UHMS guidelines, a safely run HBOT service has a written prohibited-items policy, issues or approves patient clothing, runs a pre-treatment "time-out" safety check, uses grounding straps in 100% oxygen monoplace chambers, monitors patients visually and audibly throughout, and holds regular emergency drills led by a trained safety coordinator.

The FDA advises patients to choose a facility accredited by the UHMS. Our guide on how to choose an HBOT clinic explains what else to check, and what to expect at your first session walks through the pre-session safety check.

The Bottom Line

In a medical hyperbaric chamber, leave your phone outside. Codes, safety bodies and the FDA all treat electrical devices as ignition risks in an oxygen-rich space, and fire records show that ignition sources carried in by occupants have caused chamber fires.

The chance of your phone failing during one session is small, but you do not need it inside, and a fire in 100% oxygen is severe. In an air-only mild chamber the risk is lower, but the basic rules still apply: no charging, no damaged devices and no added oxygen.

Looking for a clinic? Find HBOT clinics near you among the 1,632 facilities in 68 countries listed on hyperbaric.app.

Sources

Undersea and Hyperbaric Medical Society, Ten Guidelines for Patients and Referring Physicians in Selecting Safe Hyperbaric Oxygen Treatments (April 2025).
Burman F. Use of Lithium-Ion Batteries in Hyperbaric Chambers. International ATMO; March 2020.
Sheffield PJ, Desautels DA. Hyperbaric and hypobaric chamber fires: a 73-year analysis. Undersea Hyperb Med. 1997;24(3):153-164.
National Fire Protection Association, NFPA 99: Health Care Facilities Code, Chapter 14 Hyperbaric Facilities.
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.
U.S. Food and Drug Administration, Follow Instructions for Safe Use of Hyperbaric Oxygen Therapy Devices: Letter to Health Care Providers (25 August 2025).
U.S. Food and Drug Administration, Hyperbaric Oxygen Therapy: Get the Facts (consumer update, content current as of July 2021; archived copy).
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.
CBS Miami, Men Charged In Fatal Hyperbaric Chamber Explosion (25 April 2012).
Associated Press via News4Jax, Explosion at horse center kills worker, horse (11 February 2012).
NBC News, 4 charged in death of Michigan boy killed in hyperbaric chamber fire (10 March 2025).
WDIV ClickOnDetroit, Judge: Oxford Center workers 'actively participated' in decision to not use key safety item (11 February 2026).

This article is for information only and is not medical or engineering advice. Always follow the safety rules of the facility treating you.