Relative Humidity (RH): Waiver of Life Safety Code (LSC) Anesthetizing Location Requirements; Discussion of Ambulatory Surgical
Center (ASC) Operating Room Requirements
13-25-LSC & ASC
• RH of ≥20 Percent Permitted in Anesthetizing Locations: The Centers for Medicare & Medicaid Services (CMS) is issuing a
categorical LSC waiver permitting new and existing ventilation systems supplying hospital and critical access hospital (CAH)
anesthetizing locations to operate with a RH of ≥20 percent, instead of ≥35 percent. We are also recommending that RH not
exceed 60 percent in these locations.
• This Waiver Does Not Apply:
• When more stringent RH control levels are required by State or local laws and regulations; or
• Where reduction in RH would negatively affect ventilation system performance.
• Hospitals & CAHs Must Elect to Use the Categorical Waiver:
• Individual waiver applications are not required, but facilities are expected to have written documentation that they have
elected to use the waiver.
• At the entrance conference for any survey assessing LSC compliance, a facility that has elected to use this waiver must
notify the survey team.
• Ongoing Requirements:
• Facilities must monitor RH in anesthetizing locations and take corrective actions when needed to ensure RH remains at or
above 20 percent.
• ASCs: ASCs are not subject to all of the same LSC requirements as hospitals, but are required, consistent with 42 CFR 416.44(a)(1),
to maintain RH in operating rooms in accordance with nationally accepted guidelines.
• State Operations Manual (SOM) Appendices A, I, L & W are being updated accordingly.