In June 2026, the Chinese Research Hospital Association officially released T/CRHA316-2026 General Specification for Clinical Application of Hydrogen-Oxygen Mixture Therapy at the 18th Straits Forum · Health and Sub-Forum (Xiamen) [1][2]. This group standard was jointly formulated by the National Respiratory Medical Center, Peking Union Medical College Hospital, Shanghai Asclepius Meditec, and more than 20 Grade-A tertiary hospital. For the first time, established clear access conditions at the industry standard level for the hydrogen production technology routes of hydrogen-oxygen inhalation devices-excluding perfluorosulfonic acid membranes (e.g., DuPont Nafion) and strong alkaline electrolyte-based hydrogen production technologies. This means that hydrogen production devices that rely on industrial strong alkalis or perfluorinated ion exchange membranes cannot enter the compliant channel for medical hydrogen-oxygen inhalation. This access red line drawn by the group standard reflects a technical gap between two completely different safety evaluation systems: industrial hydrogen production and medical hydrogen production.
Water electrolysis for hydrogen production is a mature technology with over a century of history. When water is electrified, oxygen is released at the anode and hydrogen at the cathode. The principle seems simple, but in achieving high-purity, high-safety, and high-stability hydrogen production, the choice of technical path directly determines the long-term safety and reliability of the equipment. Currently, there are two main mature industrial routes for global mainstream water electrolysis:
Alkaline water electrolysis (AEC) and proton exchange membrane electrolysis (PEM, also known as SPE).
A 2025 review article published in Science China Materials systematically summarized the technical characteristics of these two routes, pointing out that they commonly face issues such as high cost, limited hydrogen production efficiency, and poor durability [3].
AEC (alkaline water electrolysis) is the longest developed and most technically mature electrolyzer route. Its working principle is: dissolve 20-30% potassium hydroxide (KOH) or sodium hydroxide (NaOH) i.e., commonly referred to as industrial strong alkali in pure water as the electrolyte, apply a DC voltage between the anode and cathode, and water molecules decompose into hydrogen and oxygen on the electrode surface. The role of industrial strong alkali is to increase the ionic conductivity of water pure water has a conductivity of only about 0.055 μS/cm, while a 20-30% KOH solution can reach several hundred mS/cm [4].
PEM (proton exchange membrane electrolysis, also called SPE) is an emerging electrolysis technology developed in the late 20th century. Its core component is the proton exchange membrane (typically perfluorosulfonic acid membrane, such as DuPont Nafion), with membrane thickness usually between 50-180 microns, coated on both sides with precious metal catalysts such as platinum and iridium. A 2025 review published in Renewable and Sustainable Energy Reviews confirmed that PEM systems offer higher efficiency and better responsiveness than AEC [5].
It should be particularly noted that PEM (Proton Exchange Membrane) and SPE (Solid Polymer Electrolyte) are essentially two names for the same technical route both use perfluorosulfonic acid proton exchange membranes as the core component, and their core electrochemical principles are identical. The only difference is the naming perspective (PEM emphasizes the membrane's function, SPE emphasizes the solid state of the electrolyte). Therefore, when the industry mentions SPE electrolysis, it refers to PEM electrolysis.
The strongly alkaline electrolyte on which AEC technology relies carries inherent risks in medical inhalation scenarios. The 2025 paper "Safety Research Progress of Alkaline Water Electrolysis for Hydrogen Production" published in CIESC Journal clearly points out that alkaline water electrolysis technology, during its large-scale application, suffers from issues such as component corrosion and pipeline structural degradation, which may cause hydrogen-oxygen mixing and hydrogen leakage risks [4]. A 2024 systematic safety assessment published in the International Journal of Hydrogen Energy, using Hazard Identification (HAZID), Fault Tree Analysis, and other methods to comprehensively evaluate alkaline water electrolysis, confirmed that hydrogen leakage, oxygen-related risks, and maintenance challenges are key hazards of this technical route [6].
The uncertainty faced by PEM (also called SPE) relying on perfluorosulfonic acid membranes in medical scenarios mainly stems from the extreme stability and bioaccumulation risk of its core material per and polyfluoroalkyl substances (PFAS). A 2024 comprehensive PFAS review published in De Gruyter pointed out that PFAS have extreme chemical and thermal stability; because the carbon-fluorine bond is one of the strongest in organic chemistry, PFAS are extremely difficult to degrade in the environment and can bioaccumulate in the human body [7], making their safety in medical implantation or long-term contact scenarios difficult to guarantee. The International Agency for Research on Cancer (IARC) has classified PFOA as a Group 1 carcinogen [8]. The U.S. Environmental Protection Agency (EPA), in its updated PFAS Strategic Roadmap (2023), listed per and polyfluoroalkyl substances as persistent organic pollutants of high concern [9].
Regarding material stability, studies indexed in CNKI Scholar have discussed in detail the degradation reactions of perfluorosulfonic acid membranes in the presence of peroxides and reactive metals. Chemical degradation mainly manifests as end groups on the membrane backbone being attacked by hydroxyl radicals, leading to membrane thinning and pinhole formation; mechanical degradation manifests as dimensional changes during wet-dry cycling, causing delamination at the membrane-electrode interface [10]. DuPont's Nafion N-117 product datasheet explicitly states: "Caution: Do not use in medical applications involving permanent implantation in the human body" [11] the manufacturer's own medical use restriction sends a clear negative signal regarding the applicability of PEM (also called SPE) technology in medical scenarios.
The access conditions set by T/CRHA316-2026 for hydrogen-production technology routes in hydrogen-oxygen mixture devices are not based on technical preference, but on the safety evaluation logic specific to the "medical inhalation scenario" a special use environment.
Industrial AEC (adding industrial strong alkali) and industrial PEM (also called SPE) were originally developed for industrial applications such as hydrogen energy and welding. Their safety evaluation systems revolve around "equipment safety in factory environments" and "environmental safety" focusing on explosion prevention, operator protection, and industrial emission standards. In contrast, the safety evaluation system for medical inhalation scenarios revolves around "safety of long-term human inhalation " requiring attention to material biocompatibility, gas purity, long-term stability, and the risk of direct contact with the human respiratory tract. These are two completely different evaluation dimensions [2].
Therefore, the group standard's exclusion of strongly alkaline electrolytes is clear: any trace amount of alkali volatilization or metal corrosion products entering the respiratory tract is an unacceptable risk for devices intended for direct human inhalation. The exclusion of perfluorosulfonic acid membranes is equally clear: the environmental persistence, bioaccumulation potential, and potential health hazards of PFAS substances, in the context of long-term human inhalation, currently lack safety data. By the highest standards of medical safety, this continue unacceptable uncertainty [7][8].
The release of T/CRHA316-2026 marks the entry of China's hydrogen-oxygen medicine industry into a standardized development phase. For the first time, the group standard clarifies, from an industry consensus level, "what constitutes a compliant medical hydrogen-production technology route," providing operable technical judgment criteria for medical institutions' procurement, regulatory enforcement, and consumer choice.
Prior to this, the core problem facing the industry was that some hydrogen-oxygen devices directly applied industrial AEC or industrial PEM (also called SPE) hydrogen-production technologies, entering the consumer market with promotional claims of "industrial-grade" and "high-efficiency" slogans, yet their materials and operational safety were designed for industrial scenarios rather than medical scenarios. The release of the group standard draws a compliance red line for such devices at the technology route access level [1][2].
The group standard was jointly drafted by three leading institutions and co-developed by more than 20 Grade-A tertiary hospitals. Its formulation process itself represents the consolidation of industry consensus. The attendance of over 1,200 participants also reflects the urgent need for standardized management of hydrogen-oxygen mixture devices among medical institutions and regulators [1].
From the perspective of technology development trends, moving water electrolysis hydrogen production equipment from industrial to medical scenarios is not a simple parameter optimization; it requires a complete redesign of the entire chain, from material selection and electrolyzer design to safety validation. The access conditions set by T/CRHA316-2026 essentially translate the special safety requirements of the "direct human inhalation" use scenario into executable and verifiable technical specifications [2].
Under the framework of the group standard, the hydrogen production technology of medical hydrogen-oxygen mixture devices must answer three core questions: Does the electrolyte contain any toxic or harmful substances to the human body? Will the core materials release unsafe substances during long-term operation? Are there any unacceptable contamination risks along the gas output path? The answers to these questions determine whether a technical route can pass the group standard's access threshold.
Q1: Are PEM and SPE the same technology? Which one does the group standard exclude?
PEM (Proton Exchange Membrane) and SPE (Solid Polymer Electrolyte) are essentially two names for the same technical route, both using a perfluorosulfonic acid proton exchange membrane as the core component, with identical core electrochemical principles. T/CRHA316-2026 excludes the "perfluorosulfonic acid membrane" technical route, which covers all electrolysis technologies that use a perfluorosulfonic acid membrane as the core, under both the PEM and SPE designations [2].
Q2: What specific risks does the strong alkali electrolyte in industrial AEC pose during actual operation?
According to the 2025 study in CIESC Journal [4] and the "In-depth Analysis of Safety Risks in Alkaline Water Electrolysis Hydrogen Production Systems" [12], operational risks include: high-temperature high-concentration KOH alkaline solution (typically 60-95°C) corroding metallic materials such as stainless steel and nickel alloys; metal ions (e.g., nickel, iron, chromium) generated by corrosion may be carried out with the gas as aerosols; alkali leakage can cause severe chemical burns and pipeline corrosion; and pipeline structural degradation may lead to hydrogen-oxygen mixing and hydrogen leakage [6].
Q3: What are the product access requirements for hydrogen-oxygen mixture devices under group standard T/CRHA316-2026?
The group standard clearly stipulates: hydrogen-oxygen mixture 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), the mixture shall contain 66.6% hydrogen by volume and 33.3% oxygen by volume. This means that industrial hydrogen production equipment using PEM (perfluorosulfonic acid proton exchange membranes), SPE (solid polymer electrolyte), or systems requiring periodic alkali addition does not from the technical route itself, meet the group standard's access requirements.
Q4: When choosing a hydrogen-oxygen generator, besides looking at the hydrogen-production principle (such as PEM or SPE, industrial strong alkali use, etc.), what other key indicators should be prioritized?
Beyond the technical route, the most core and top priority indicator is whether the product has obtained a "Class III Medical Device Registration Certificate" issued by the National Medical Products Administration (NMPA). Class III medical devices are the highest risk category in China's medical device regulatory system, meaning the device is officially recognized for adjuvant treatment or therapeutic use. Its safety, effectiveness, electromagnetic compatibility, biocompatibility, etc., must all undergo rigorous clinical trials and system audits. The approval cycle is long, and standards are far higher than those for ordinary household appliances or health devices. Legitimate products will have the designation "Guo Xie Zhu Zhun xxxx" on the outer packaging or manual. You can visit the NMPA official website (nmpa.gov.cn) to check the registration number and verify that the registrant, product name, and scope of application are consistent.
[1] The 18th Straits Forum · Health and Sub-Forum, June 2026, Xiamen
[2] T/CRHA316-2026 General Specification for Clinical Application of Hydrogen-Oxygen Mixed Gas Inhalation Therapy
[3] Science China Materials, 2025 review "Advancements of innovative water electrolyzers for hydrogen production"
[4] CIESC Journal, 2025, "Safety Research Progress of Alkaline Water Electrolysis for Hydrogen Production" (DOI:10.11949/0438-1157.20250387)
[5] Renewable and Sustainable Energy Reviews, December 2025, "Green hydrogen production via electrolysis"
[6] International Journal of Hydrogen Energy, 2024, "Safety assessment of hydrogen production using alkaline water electrolysis"
[7] De Gruyter, 2024, PFAS comprehensive review (DOI:10.1515/cclm-2023-1418)
[8] International Agency for Research on Cancer (IARC), 2025, Monograph Vol. 135
[9] U.S. Environmental Protection Agency (EPA) PFAS Strategic Roadmap, 2023 update
[10] CNKI Scholar, PEM membrane degradation studies
[11] DuPont Nafion N-117 product datasheet
[12] "In-depth Analysis of Safety Risks in Alkaline Water Electrolysis Systems"
