Hyperbaric oxygen therapy （HBO） is a treatment in which 100％ oxygen is inhaled under a treatment pressure of 2.0ATA more. This has been recognized to be effective for improving hypoxia and infections. However, a fire source was introduced into the HBO chamber, causing five explosions and killing all the patients.
The cause of the fire and explosion was a burning charcoal body warmer not needed for treatment, a burning platinum body warmer, and a disposable body warmer made from the heat of a chemical reaction of iron oxide （FeO₂） that had been brought into the HBO chamber and occurred after the HBO had started.
57 years have passed since the first fire body warmer accident and 27 years since the “disposable body warmer” accident, and no major accidents have been reported since then. However, it is assumed that near-misses have occurred on an isolated basis. This is because the long history of no accidents has led to a lack of awareness of the dangers of the “disposable body warmer” and there is a risk that body checks before treatment may be neglected in the HBO room. Also, the fact that no data has been shown on the actual exposure of the “disposable body warmer” to high concentrations of oxygen is also a factor in the lack of awareness of the danger.
This experiment was conducted in collaboration with Kyushu University of Medical Science （Clinical Engineering） in which disposable body warmers were exposed to high concentrations of oxygen under atmospheric pressure and the temperature rise was measured. The results showed that when exposed to oxygen, disposable body warmers reached dangerously high temperatures of over 100℃ within minutes, and it was estimated that the burning rate and temperature would increase further inside the HBO chambers.

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A body checks of the patient before hyperbaric oxygen therapy （HBO） is necessary and important to prevent accidents. This is a lesson learned from the past HBO disaster. In particular, the cause of the HBO chamber fire and explosion that occurred in February 1996 was a “disposable body warmers” It has been found that disposable body warmers can reach extremely high temperatures, and patients’ belongings and body checks must be rigorously inspected before being placed in the HBO chamber.
However, there is no effective tool other than a metal detector to detect “disposable body warmers.” Therefore, we visualized the temperature using a sensing device （Infrared Thermal Imaging Camera） that combines an infrared gadget and a mobile camera.

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