# COVID-19 and molecular hydrogen inhalation.
> COVID-19と分子状水素吸入に関する考察


## 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](https://pubmed.ncbi.nlm.nih.gov/32865158/)
- **DOI**: [10.1177/1753466620951051](https://doi.org/10.1177/1753466620951051)
- **PMC**: [PMC7459175](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7459175/)
- **Study type**: letter
- **Delivery route**: inhalation
- **Effect reported**: not assessed

## Delivery context

For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.

## Safety notes

For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [LFL / UFL terminology](https://h2-papers.org/en/safety-notes/lfl-ufl-explained)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 32865158. https://h2-papers.org/en/papers/32865158
> **Source**: PubMed PMID [32865158](https://pubmed.ncbi.nlm.nih.gov/32865158/)