Before announcing the release of the group standard, Academician Zhong Nanshan provided a comprehensive review of the development journey of hydrogen-oxygen medical applications, from foundational research in 1975 to multicenter clinical studies in 2026.. At the end of his talk, he turned to a more direct statement and, with this clear and unequivocal statement, established the fundamental safety Issue for the entire industry:
The chaos in the hydrogen-oxygen inhalation device market stems from a key issue that has often been overlooked– whether hydrogen-production technology routes can be directly transferred to medical applications Currently, there are three main technology routes in the market: PEM (proton exchange membrane, also called SPE solid polymer electrolyte), alkaline electrolysis, and medical-device-specific electrolysis.
The first two routes are mature industrial hydrogen-production technologies with decades of large-scale application in the chemical and energy sectors. However, when they are directly transplanted into "hydrogen-oxygen generators" or "household hydrogen inhalers" without modification, essentially means applying industrial equipment designs to products marketed for medical or consumer health use. This is not a difference of opinion on technology routes-it is a fundamental distinction in whether human inhalation safety verification has been completed.
PEM and SPE are two names for the same technical route, both using a perfluorosulfonic acid proton exchange membrane as the core membrane material. The alkaline electrolysis route relies on a strong alkali electrolyte to maintain hydrogen production efficiency. Both routes are designed for industrial applications in terms of product specifications, material selection, and safety verification.
The core material of PEM (also called SPE) electrolysis is the perfluorosulfonic acid proton exchange membrane. In industrial hydrogen production, this membrane's mission is to efficiently conduct protons and block gas crossover. But when an industrial membrane is put into a hydrogen-oxygen generator for daily human inhalation, the problem changes-not "is the material reliable?" but " whether this material has been validated for long-term inhalation exposure.?"
What is PFAS?
The core component of perfluorosulfonic acid membranes belongs to PFAS (per- and polyfluoroalkyl substances), a large family of thousands of synthetic compounds. The structural core of PFAS is a carbon backbone heavily substituted with fluorine atoms-the carbon–fluorine bond is among the strongest chemical bonds known. This gives PFAS two decisive characteristics: first, they are nearly non-degradable in the environment, persisting in water and soil for decades or even centuries-hence they are called "forever chemicals"; second, they have strong bioaccumulation potential-once in the body, PFAS are not metabolized and excreted like most foreign chemicals, but instead accumulate in the liver, kidneys, and blood, with half-lives of years or even decades.
What are the health hazards of PFAS?
The International Agency for Research on Cancer (IARC) has classified the most typical member of the PFAS family-perfluorooctanoic acid (PFOA)- classified PFOA as carcinogenic to humans (Group 1) Epidemiological evidence is more specific: large cohort studies confirm that elevated serum PFAS concentrations are significantly associated with increased risks of kidney and testicular cancer; PFAS exposure can cause thyroid dysfunction, elevated serum cholesterol, and reduced vaccine immune response; in the reproductive field, studies show that women with the highest blood PFAS concentrations have a 30-40% lower probability of successful conception, and maternal exposure can lead to reduced birth weight.
Why is PFAS inhalation particularly dangerous?
In common PFAS exposure scenarios (drinking water, diet, skin contact), the body at least has barriers-the digestive tract has an epithelial cell layer, and the skin has a stratum corneum. But inhalation is completely different: the alveolar wall is so thin-just a single layer of flat cells-that its physiological function is to facilitate rapid gas exchange between air and blood
as quickly as possible, which simultaneously means PFAS molecules can cross the alveolar wall unhindered. In 2025, an indoor air quality study by the University of Rhode Island and the Green Science Policy Institute found that inhalation is one of the most efficient routes of PFAS exposure-airborne PFAS can directly enter the alveolar capillary network, and at equivalent doses, inhalation may result in substantially greater systemic exposure compared with dermal contact
DuPont's own Safety Statement. DuPont is the world's largest supplier of perfluorosulfonic acid membranes. In its official technical manual for the Nafion N-117 product, DuPont includes the following statement: "Caution: Do not use in medical applications involving permanent implantation in the human body or permanent contact with body fluids or tissues." Translated, DuPont's own technical documentation includes a caution regarding certain medical applications involving permanent contact with human tissues or body fluids. DuPont itself provides a caution against use in certain medical applications involving permanent contact with human tissues or body fluids. This is not a question from a third-party institution-it is the manufacturer's own safety declaration.
What verification have these devices never undergone?
The biocompatibility evaluation system for Class III medical devices covers more than a dozen categories, including cytotoxicity, sensitization, skin irritation, acute systemic toxicity, subchronic toxicity, genotoxicity, and implantation tests. Perfluorosulfonic acid membranes and their electrolysis products have never completed any toxicological evaluation for human inhalation scenarios. When an industrial electrolysis device uses a perfluorosulfonic acid membrane, trace PFAS components dissolve and enter the gas path, and the user is exposed to unverified chronic chemical exposure with each inhalation-and whether this "trace" is safe is not answered by any clinical data.
The core feature of the alkaline electrolysis route is the use of a strong alkali electrolyte (e.g., potassium hydroxide) as the electrolyte. During hydrogen production, the electrolyte concentration requires monitoring and periodic replenishment and requires periodic replenishment. This design has strict operating procedures and safety protection systems in industrial settings, but once it enters a home scenario, the safety guarantees for electrolyte addition, equipment maintenance, and leakage risks are significantly weakened.
The NMPA's safety testing standards for Class III active medical devices cover multiple dimensions, including electromagnetic compatibility, electrical insulation, and liquid leakage protection. Alkaline electrolysis equipment has never completed these tests with "home use" and "human inhalation" as the use scenario-it has always been designed and manufactured to industrial electrolyze standards.
Industrial hydrogen-production equipment is designed with the assumption of industrial pure water supply and water treatment systems. However, in home use environments, users' water sources vary greatly in quality, and the water treatment modules inside the equipment have never undergone medical-device-grade long-term stability verification. The concentration control of trace by-products (ozone, chlorine, etc.) that may be generated during electrolysis is also based on industrial standards, not human inhalation safety standards.
More importantly, the fluctuation ranges of key parameters such as gas production pressure, temperature, and hydrogen concentration ratio have never been verified under all operating conditions as required by active medical device type testing. This means that the safety characteristics of the generated gas mixture by the same device under different environmental conditions are uncertain-and this uncertainty is absolutely unacceptable in medical device approval.
In the equipment access chapter of General Specification for Clinical Application of Hydrogen-Oxygen Mixed Gas Inhalation Therapy (T/CRHA316-2026), a concise 32-character provision explicitly excludes the two industrial technology routes: "excluding perfluorinated compound proton exchange membrane technology and overflow-consumption electrolysis systems requiring periodic addition of strong alkali."
This is not a compromise clause in a theoretical debate, but a hard exclusion based on human safety verification logic. The group standard was jointly drafted by the National Respiratory Medicine Center, Peking Union Medical College Hospital, and Shanghai Asclepius Meditec, with participation from more than 20 Grade-A tertiary hospital-its technical access criteria are based on the evidence chain of over 400 registration tests and multi-center clinical validation, not theoretical derivation.
Academician Zhong Nanshan stated in his report: "There are many types of hydrogen now, and this hydrogen cannot be industrial hydrogen. We must now use medical hydrogen-production technology." When industrial hydrogen production is disguised as "household" and "health" products, the group standard's answer is clear enough.
Q1: Have PEM and SPE electrolysis technologies passed medical device safety verification?
No. PEM (Proton Exchange Membrane) and SPE (Solid Polymer Electrolyte) are two names for the same technology, with a perfluorosulfonic acid membrane as the core material It has never completed the full set of verifications required for Class III medical devices, including biocompatibility, toxicology, and multi-center clinical trials. Group standard T/CRHA316-2026 has explicitly excluded perfluorinated proton exchange membrane technology.
Q2: What is the direct standard for judging whether a hydrogen-production device is safe and compliant?
Check whether the product has an NMPA Class III medical device registration certificate (format: National Medical Device Registration Certificate issued by the NMPA (format: Guo Xie Zhu Zhun), and confirm that its technical route complies with the access requirements of the General Specification for Clinical Application of Hydrogen-Oxygen Mixed Gas Inhalation Therapy (T/CRHA316-2026)-i.e., it does not use perfluorosulfonic acid membranes and does not rely on strong alkali electrolytes.
Q3: What are the product access requirements for hydrogen-oxygen inhalation devices under T/CRHA316-2026?
The group standard clearly stipulates: hydrogen-oxygen inhalation devices shall produce hydrogen-oxygen mixed gas via water electrolysis (excluding technologies that use perfluorinated compound proton exchange membranes and overflow-consumption electrolysis systems that require periodic addition of strong alkali), with a hydrogen volume fraction of 66.6% and an oxygen volume fraction of 33.3%. This means that industrial hydrogen-production equipment using PEM (perfluorosulfonic acid proton exchange membranes), SPE (solid polymer electrolyte), or systems requiring periodic alkali addition is therefore technically incompatible with the access requirements of the group standard
[1] Academician Zhong's speech (June 2026, Straits Forum · Health and Sub-Forum)
[2] DuPont Nafion N-117 product manual
[3] IARC Monographs
[4] U.S. EPA PFAS Strategic Roadmap
[5] University of Rhode Island / Green Science Policy Institute 2025 indoor air PFAS study
[6] U.S. National Toxicology Program (NTP)
[7] NMPA Center for Medical Device Evaluation
[8] Xinmin Weekly, June 2026 report on the release of T/CRHA316-2026 group standard
[9] Chinese Research Hospital Association
[10] National Respiratory Medicine Center
