Aorn Humidity Guidelines Jun 2026

Here are the AORN (Association of periOperative Registered Nurses) humidity guidelines for operating rooms (ORs), based on the latest recommended practices. Core AORN Humidity Standard Relative humidity (RH) in the operating room should be maintained between 20% and 60% . This range applies:

During all surgical procedures When sterile supplies are open or exposed When the room is occupied for surgery

Key Points of the AORN Guideline (Updated) 1. Change from previous standard

Older standard (pre-2021): 20–60% (with a target of 50–55%) Current standard (AORN 2021 & later): 20–60% (no minimum above 20% required) aorn humidity guidelines

AORN removed the previous recommendation for a lower limit of 30% or 35% due to lack of evidence linking 20–30% RH to increased SSIs. 2. Lower limit: 20% rationale

Levels below 20% increase risk of static electricity discharge (rare with modern equipment) and may dry mucous membranes No proven increase in surgical site infections (SSIs) at 20–30% range

3. Upper limit: 60% rationale

Humidity >60% promotes bacterial and fungal growth Increases risk of moisture wicking into sterile packages Associated with higher SSI rates in some studies Causes surgeon and staff discomfort (heat stress)

Alert & Action Criteria | Condition | AORN Action | |-----------|--------------| | RH <20% for >15 minutes | Notify biomed / engineering; document; evaluate if surgery should continue (rarely cancels unless static risk present) | | RH >60% for >15 minutes | Investigate cause; reduce humidity; inspect sterile supplies for moisture compromise; replace compromised items | | RH deviates during active surgery | Continue case if clinically necessary; correct ASAP; document deviation | Exceptions & Special Cases

Orthopedic implant cases: Some facilities tighten range (30–55%) but AORN does not mandate this Burn ORs: May use higher humidity (40–60%) for patient thermoregulation Hybrid ORs (with imaging): Equipment may require 30–60% – follow manufacturer specs Here are the AORN (Association of periOperative Registered

Monitoring Requirements

Continuous real-time monitoring Visible display inside OR Audible/visual alarm for out-of-range conditions Calibrated sensors checked per facility policy (typically annually) Logged daily (or per case) in many facilities