# Beneficial effects of hydrogen gas inhalation on a murine model of allergic rhinitis.
> アレルギー性鼻炎マウスモデルにおける水素ガス吸入の有益な効果


## Abstract

Allergic rhinitis (AR) is a chronic inflammatory condition in which oxidative stress is thought to play a contributing role. Using an ovalbumin (OVA) sensitization and intranasal challenge protocol in female BALB/c mice, this study examined the effects of high-concentration H2 gas inhalation at varying frequencies and durations. OVA challenge produced marked nasal mucosal inflammation. H2 inhalation reduced inflammatory cell infiltration into the nasal mucosa and decreased serum concentrations of IL-5, IL-13, and monocyte chemoattractant protein-1. Interferon-γ showed a slight, non-significant increase. Body weight loss observed in AR mice was reversed by H2 exposure, while weight gain in healthy mice was modestly limited. The protective effects were dose-dependent, suggesting that H2 inhalation may have value in managing allergic airway inflammation.

### Mechanism

H2 inhalation suppressed Th2-associated cytokines (IL-5, IL-13) and MCP-1 in serum, reducing inflammatory cell infiltration into nasal mucosa, likely through its antioxidative properties that attenuate oxidative stress-driven allergic inflammation.

## Bibliographic

- **Authors**: Fang S, Li XM, Wei X, Zhang YJ, Ma Z, Wei Y, et al.
- **Journal**: Exp Ther Med
- **Year**: 2018
- **PMID**: [30542474](https://pubmed.ncbi.nlm.nih.gov/30542474/)
- **DOI**: [10.3892/etm.2018.6880](https://doi.org/10.3892/etm.2018.6880)
- **PMC**: [PMC6257674](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6257674/)
- **Study type**: animal study
- **Delivery route**: inhalation
- **Effect reported**: positive

## 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 30542474. https://h2-papers.org/en/papers/30542474
> **Source**: PubMed PMID [30542474](https://pubmed.ncbi.nlm.nih.gov/30542474/)