A former safety manager at a Michigan wellness center has been sentenced to prison after a hyperbaric oxygen chamber caught fire and exploded with a 5-year-old boy trapped inside.

Jeffrey Mosteller, 66, was sentenced to between 19 months and 15 years in prison after pleading no contest to involuntary manslaughter in the death of Thomas Cooper. Authorities say basic safety protocols designed to prevent exactly this kind of fire were ignored at the facility.

The tragedy has also renewed questions about the growing use of hyperbaric oxygen therapy outside traditional medical settings, particularly when the treatment is promoted for conditions that are not approved uses.

What Happened to Thomas Cooper?

Thomas Cooper was receiving hyperbaric oxygen therapy at the Oxford Center in Troy, Michigan, on January 31, 2025.

The 5-year-old was being treated for attention deficit hyperactivity disorder (ADHD) and sleep apnea.

During the session, a fire started inside the oxygen-rich hyperbaric chamber and caused an explosion.

Thomas was killed.

His mother, Annie Cooper, was nearby and suffered serious burns while desperately trying to rescue her son.

Why a Hyperbaric Chamber Fire Is So Dangerous

Hyperbaric oxygen therapy involves breathing highly concentrated oxygen inside a pressurized chamber.

The treatment has legitimate medical uses, including certain serious wounds and other specific conditions. But the oxygen-rich environment also means fire prevention procedures are extremely important.

Materials that might normally burn relatively slowly can ignite much more aggressively when surrounded by concentrated oxygen.

Even a tiny spark can therefore become catastrophic.

Investigators alleged that important safety measures were not being followed at the Oxford Center when Thomas died.

Prosecutors Say Safety Protocols Were Ignored

According to the Michigan Attorney General’s Office, both the National Fire Protection Association and the manufacturer of the chamber had published strict safety procedures for operating the equipment.

Prosecutors say those standards were deliberately disregarded.

Mosteller served as the Oxford Center’s safety manager, putting him in a position where ensuring those procedures were followed was a central responsibility.

Michigan Attorney General Dana Nessel described Thomas’ death as completely preventable and said Mosteller had allowed outdated equipment to continue operating despite established safety standards.

Grounding Straps Became a Key Issue

One particularly important safety measure involved grounding straps.

These straps help discharge static electricity and reduce the possibility of a spark developing inside the chamber.

The Oxford Center reportedly did not use them.

Mosteller’s attorney said that the practice of not using grounding straps existed before he began working at the facility. However, the defense acknowledged that he failed to correct the dangerous practice after taking responsibility for safety.

In an environment filled with concentrated oxygen, that failure had potentially devastating consequences.

How Could the Fire Have Started?

Experts examining the incident have pointed to static electricity as a likely source of ignition.

Thomas reportedly moved enough inside the chamber to displace a sheet covering the mattress.

That movement may have generated a static spark.

In an ordinary environment, such a spark might be harmless. Inside an oxygen-rich hyperbaric chamber, however, it can ignite combustible material almost instantly.

The resulting flash fire engulfed the chamber within seconds.

Judge Criticizes Mosteller’s Failure to Act

During sentencing, Oakland County Circuit Court Judge Kwamé Rowe focused on Mosteller’s responsibility as the facility’s safety manager.

The judge emphasized that Mosteller was in a position to challenge unsafe practices.

His attorney described what happened as a horrific mistake and acknowledged that Mosteller failed to correct procedures that were already in place when he arrived.

Mosteller declined to address the court during sentencing.

Thomas’ family also did not attend or provide a victim-impact statement, with prosecutors explaining that discussing the tragedy remained too painful for them.

Mosteller Could Spend Up to 15 Years in Prison

Mosteller pleaded no contest to one count of involuntary manslaughter in July.

Under the plea and sentencing agreement, he received a minimum prison sentence of 19 months.

However, the maximum term is 15 years.

A no-contest plea does not technically admit guilt but allows the court to treat the defendant as guilty for sentencing purposes.

Mosteller is the first of several Oxford Center employees charged in connection with Thomas’ death to reach this stage of the criminal proceedings.

Three Other Employees Still Face Charges

Mosteller was one of four people charged over the fatal explosion.

Oxford Center owner Tamela Peterson and management assistant Gary Marken have faced second-degree murder charges, with involuntary manslaughter listed as an alternative charge.

Aleta Moffitt, who operated the hyperbaric chamber, has faced involuntary manslaughter and an additional allegation involving intentionally placing false information in a medical record.

Their cases remain separate from Mosteller’s plea and sentencing.

The fact that Mosteller accepted a plea agreement does not determine the guilt or innocence of the other defendants.

Thomas Was Receiving Therapy for ADHD and Sleep Apnea

Another issue surrounding the tragedy is why Thomas was undergoing hyperbaric oxygen therapy in the first place.

Hyperbaric oxygen therapy is used for certain recognized medical conditions, but ADHD and sleep apnea are not among its standard approved indications.

The Oxford Center promoted hyperbaric oxygen therapy for a wide range of conditions.

The Guardian previously reported that the center marketed the therapy for more than 100 conditions, including ADHD, autism and sleep apnea.

That reflects a broader trend in which hyperbaric chambers have expanded beyond hospitals and specialized medical facilities into wellness businesses.

Hyperbaric Oxygen Therapy Has Become a Wellness Trend

Hyperbaric oxygen therapy itself is not new.

When administered for appropriate conditions by properly trained medical professionals using correctly maintained equipment, it has established medical applications.

But the treatment has increasingly been marketed for wellness, longevity and conditions where evidence of benefit may be limited or nonexistent.

Hyperbaric medicine experts have raised concerns about facilities operating without sufficient medical oversight or following inconsistent safety standards.

The danger is particularly significant because the combination of pressurization and concentrated oxygen creates risks that may not be obvious to consumers.

Thomas’ Death Could Lead to Broader Changes

The tragedy has already generated discussion about whether stronger oversight of hyperbaric oxygen facilities is needed.

Experts have argued that facilities offering the treatment should follow recognized accreditation and safety standards.

The Guardian reported that Michigan lawmakers have considered requiring hyperbaric oxygen facilities to obtain accreditation from the Undersea and Hyperbaric Medical Society.

Such requirements could establish more consistent rules around equipment maintenance, employee training, medical supervision and fire prevention.

A Preventable Tragedy With Legal Consequences Still Unfolding

For Thomas Cooper’s family, no prison sentence can undo what happened inside the Oxford Center.

A 5-year-old boy entered a hyperbaric chamber for treatment and never came out alive. His mother was injured trying to save him, and investigators later alleged that established safety procedures that might have prevented the disaster had been ignored.

Mosteller’s sentence represents the first major criminal resolution arising from the explosion.

But the legal case is not finished.

Other former employees still face proceedings, while Thomas’ parents have also pursued a wrongful-death lawsuit.

Beyond those cases, the tragedy has become a warning about what can happen when powerful medical equipment is used without rigorous adherence to safety standards.