Hydrogen gas (XEN) inhalation ameliorates airway inflammation in asthma and COPD patients
Wang ST et al. · QJM. 2020;113(12):870–875.
Study at a glance
Human
Adults with asthma or chronic obstructive pulmonary disease
A hydrogen-containing steam/air mixture inhaled once for 45 minutes · The generator initially produced 67% H₂/33% O₂, but an oxygen-adsorption cartridge removed O₂ before inhalation. Device gas was about 2.4% H₂ and nasal-cannula concentration about 0.1–0.3%.
One 45-minute inhalation session
Some cytokines decreased, others did not, and one marker increased. No symptom, lung-function or longer-term clinical outcome was tested.
Acute uncontrolled study with 10 people per condition and many biomarkers. It cannot establish clinical benefit. Chinese public programs funded the study; authors declared no conflict.
What kind of evidence is this?
Human
Prospective uncontrolled before-and-after study
Respiratory health
Inhaled H₂
Information not yet classified
Some editorial classification fields are still pending. The source-reported outcomes and result are shown below; Hydrogenology does not infer a positive or negative signal from prose automatically.
Methods
Adults with asthma or chronic obstructive pulmonary disease
20 participants: asthma n=10, COPD n=10
One 45-minute inhalation session
A hydrogen-containing steam/air mixture inhaled once for 45 minutes
H₂ in steam/air after device oxygen removal — not Brown’s gas at the point of delivery.
The generator initially produced 67% H₂/33% O₂, but an oxygen-adsorption cartridge removed O₂ before inhalation. Device gas was about 2.4% H₂ and nasal-cannula concentration about 0.1–0.3%.
Not reported. Total outlet flow was not provided, so H₂ flow in mL/min cannot be calculated.
O₂ was generated upstream but reportedly removed by a cartridge before inhalation; delivered O₂ flow was not reported.
No concurrent comparator
Outcomes and reported result
Blood and exhaled-breath-condensate cytokines
Some cytokines decreased, others did not, and one marker increased. No symptom, lung-function or longer-term clinical outcome was tested.
Gas pathway, concentration, main biomarker results, funding and conflict statement checked in the free full text; flow remains unreported.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Acute uncontrolled study with 10 people per condition and many biomarkers. It cannot establish clinical benefit. Chinese public programs funded the study; authors declared no conflict.
Adults with asthma or COPD under a single short inhalation protocol.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 32407476 · DOI: 10.1093/qjmed/hcaa164
Open-access article.
Free full text on PMC and Oxford Academic; identifiers cross-checked in PubMed.
10 August 2026
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