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AAMI standards, PAA & H₂O₂, and what sterile processing teams need to know now

Chemical sterilants and high-level disinfectants, such as hydrogen peroxide (H₂O₂) and peracetic acid (PAA), are critical tools in sterile processing. However, they’re also reactive, irritating, and (in some workflows) airborne. That’s why the latest AAMI guidance is putting a much stronger spotlight on workplace safety, environmental monitoring, verification, and risk-based decision making. Below, we summarize the essentials you should weave into your processes today, with specific tie-ins to AAMI ST91 (endoscope processing) and the recent AAMI ST58 updates on chemical monitoring and worker safety.

AAMI standards overview

AAMI standards are consensus, evidence-informed guidance used by healthcare facilities to align practice, protect patients, and reduce staff exposure risk. Two recent and relevant developments to these standards include:

  • AAMI ST91 (Flexible and Semi-Rigid Endoscope Processing) codifies safe endoscope workflow and facility design that directly affects where and how chemical disinfectants are used. ST91’s recommended separation of “dirty”/decontamination spaces from “clean” areas, along with role-based access and a clarified workflow, reduces opportunities for uncontrolled releases and unnecessary exposures to chemicals like PAA.
  • AAMI ST58 underwent a significant update to chemical sterilization and HLD guidance, placing greater emphasis on worker safety, environmental and process monitoring, device/chemical compatibility, and risk-based selection of sterilants. The 2024 edition replaces older guidance (bringing together and updating previous documents such as ST41) and explicitly elevates monitoring and occupational safety as areas of key consideration.

What ST58:2024 changed about chemical monitoring

Key takeaways from the ST58:2024 updates relevant to PAA and H₂O₂ workflows:

  • Stronger emphasis on environmental/air monitoring and engineering controls: ST58:2024 calls for more rigorous assessment of emissions from chemical sterilization systems and for facilities to ensure proper ventilation, capture, and monitoring strategies.
  • Worker safety & toxicity considerations: Selection and evaluation of sterilants should factor in toxicity and exposure routes. That means facilities must weigh operational benefits against occupational health risk and implement controls accordingly.
  • Clarity on validation and process monitoring: ST58 clarifies validation approaches for liquid chemical sterilization versus gaseous systems and emphasizes routine product/process testing and monitoring to detect leaks, off-gassing, or failed containment.

How ST91 connects the dots (endoscope processing implications)

Endoscope reprocessing frequently uses high-level disinfectants like PAA. ST91’s design and workflow recommendations reduce cross-contamination and exposure risk by:

  • Specifying physical layout and control of decontamination areas so that chemical cleaning and disinfection occur in spaces with appropriate ventilation and restricted access.
  • Recommending standardized cleaning timing, verification steps, and PPE that, when used together, lower the chance of incidental exposures.

When you combine ST91’s operational controls with ST58’s monitoring and selection guidance, you get a stronger, layered protection strategy for staff, minimizing exposure to hazardous chemicals and increasing workflow efficiency.<

Practical checklist for SPD / endoscopy teams 

  1. Map your chemical workflows: Document where PAA/H₂O₂ are used (point-of-use, washers, immersion baths, automated reprocessors, gaseous sterilizers) and who is present during the tasks. (ST58 encourages process-level thinking)
  2. Upgrade ventilation & containment where needed: If tasks occur in rooms that are not mechanically ventilated or do not adhere to recommended air change rates, prioritize engineering fixes or local capture/abatement.
  3. Implement routine area monitoring: Use validated methods and instruments appropriate for PAA and H₂O₂. Leverage data to identify trends and possible areas of concern.
  4. Match PPE and policies to risk: ST91 and ST58 reinforce training, proper protocols, and role-based PPE (gloves, eye/face protection, and respiratory protection where engineering controls are lacking).
  5. Validate and monitor equipment: Follow manufacturer instructions for use, perform preventive maintenance, and monitor sterilizer exhaust/emission performance. ST58 highlights how device age and maintenance affect emissions.
  6. Recordkeeping & action levels: Define alarm/action levels for your monitors (aligned with ACGIH/OSHA guidance, where applicable), document events, and have rapid response plans for when occupational exposure limits are exceeded.

Final thought: standards are tools, not checkboxes

AAMI ST91 and ST58 aren’t just new documents to file away; they reflect a shift toward treating occupational safety as central to sterilization and reprocessing. The easiest path to compliance and safer workplaces is a layered approach: redesign workflows per ST91, choose sterilants and processes with the occupational safety profile in mind per ST58, implement engineering and PPE controls, and validate those controls with ongoing monitoring and maintenance.

References and Resources

ANSI/AAMI ST58:2024 – Chemical sterilization and high-level disinfection in health care facilities. Association for the Advancement of Medical Instrumentation (AAMI), 2024.

“The 2024 AAMI ST58 Update: What Sterile Processing and Infection Prevention Professionals Need to Know,” ASP. https://www.asp.com/en-us/2024-aami-st58-update-sterile-processing-infection-prevention

“ANSI/AAMI ST91: Flexible and semi-rigid endoscope processing in health care facilities — White Paper, 2022-03-10,” Healthmark (via hmark.com).