Guidelines for the selection of hydrogen gas inhalers based on hydrogen explosion accidents

Despite the fact that we have reported on the dangers of the explosion of hydrogen gas inhalers, hydrogen gas inhalers with explosive hazards are, as a matter of fact, still being sold today. In this study, we investigated past reports of hydrogen gas inhaler explosion accidents to clarify the causes of these explosion incidents. As a result of this investigation, we found that the central cause was the leakage of hydrogen gas inside the hydrogen gas inhaler. Although it is said that the explosive concentration of hydrogen is between 10% and 75%, and that the gas does not explode above 75% due to the lack of oxygen, we confirmed through a series of ignition experiments that explosions can occur even in hydrogen gas inhalers that produce 100% hydrogen gas. Some manufacturers of such highly concentrated hydrogen gas inhalers claim that the high concentration and purity of hydrogen is safe and that there is no risk of explosion. We believe that manufacturing or selling such products that pose a risk of explosion or detonation is a violation of social justice. This paper presents ideas for selecting safe hydrogen gas inhalers based on a survey of past accident cases.