H₂ Papers

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COVID-19 and molecular hydrogen inhalation.

COVID-19と分子状水素吸入に関する考察

letter inhalation not assessed

Abstract

This letter discusses the potential relevance of molecular hydrogen (H2) inhalation in the context of COVID-19. H2 is recognized for its antioxidant and anti-inflammatory properties, and the author explores whether these characteristics may be relevant to respiratory complications and oxidative stress associated with COVID-19 infection. No detailed abstract is available for this publication, but the correspondence addresses the scientific rationale for considering H2 inhalation in this disease context.

Mechanism

H2 may reduce oxidative stress and inflammatory responses associated with COVID-19 through its established antioxidant and anti-inflammatory properties.

Bibliographic

Authors
Ostojic SM
Journal
Ther Adv Respir Dis
Year
2020
PMID
32865158
DOI
10.1177/1753466620951051
PMC
PMC7459175

Tags

Disease:COVID-19 (25) Delivery:inhalation delivery (196) Mechanism:antioxidant enzymes (423) anti-inflammatory (743) oxidative stress (899) reactive oxygen species (774)

Delivery context

In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.

→ Evidence by delivery route

Safety notes

In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.

See also:

Other papers on the same disease / condition