# A possible prevention strategy of radiation pneumonitis: combine radiotherapy with aerosol inhalation of hydrogen-rich solution.
> 水素リッチ溶液のエアロゾル吸入と放射線療法の併用による放射線肺炎予防戦略の提案


## Abstract

Radiation pneumonitis represents a significant barrier to dose escalation in radiotherapy. Molecular hydrogen has been identified as a potentially safe radioprotective agent owing to its selective scavenging of hydroxyl radicals and peroxynitrite. Because the majority of ionizing radiation-induced cellular injury is attributable to hydroxyl radical generation, this paper proposes that aerosol inhalation of hydrogen-rich physiological saline combined with radiotherapy could serve as a novel preventive approach against radiation pneumonitis. The use of hydrogen-saturated saline rather than pure hydrogen gas is emphasized for safety reasons, given the explosive nature of gaseous hydrogen at high concentrations.

### Mechanism

Molecular hydrogen selectively neutralizes hydroxyl radicals and peroxynitrite generated by ionizing radiation, thereby reducing radiation-induced cellular damage without interfering with the therapeutic effects of radiotherapy.

## Bibliographic

- **Authors**: Chuai Y, Zhao L, Ni J, Sun D, Cui J, Li B, et al.
- **Journal**: Med Sci Monit
- **Year**: 2011
- **PMID**: [21455114](https://pubmed.ncbi.nlm.nih.gov/21455114/)
- **DOI**: [10.12659/msm.881698](https://doi.org/10.12659/msm.881698)
- **PMC**: [PMC3539519](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3539519/)
- **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 21455114. https://h2-papers.org/en/papers/21455114
> **Source**: PubMed PMID [21455114](https://pubmed.ncbi.nlm.nih.gov/21455114/)