Compliance · United States Pharmacopeia
USP General Chapter <797>: pharmaceutical compounding, sterile preparations
Indoor: sterile compounding pharmacies (USA)
USP General Chapter <797>, Pharmaceutical Compounding — Sterile Preparations, sets the standards for compounding sterile medications, in a revision that became official on November 1, 2023. Its facility requirements are built on the ISO 14644-1 cleanliness classes. The primary engineering control where compounding happens operates at ISO Class 5 (3,520 particles/m³ at ≥0.5 µm). It sits inside an ISO Class 7 buffer room (352,000 particles/m³) with at least 30 air changes per hour, held at a positive pressure of at least 0.020 inches of water column (about 5 Pa) relative to adjacent, less clean areas. Relative humidity in compounding areas is held at 60 % or below.
Limit values
USP 797 Limit Values
Every value United States Pharmacopeia publishes for the 3 parameters below, with its averaging period, as the standard states it.
Who it applies to
Who Must Comply
Pharmacies, hospitals, outsourcing facilities, and clinics that compound sterile preparations in the United States, as enforced by state boards of pharmacy and accreditors. Hazardous drugs add the requirements of USP <800>.
Monitoring
How Monitoring Demonstrates Compliance
Classification and certification are periodic: certified particle counts and airflow tests at set intervals, following ISO 14644. What has to be shown continuously is the pressure relationship, which the chapter expresses as a number, with temperature and humidity recorded alongside. A continuous record with alarms shows the cascade held between certifications and flags a door, filter, or fan problem when it happens.
Recommended
best match-
Industrial monitor for indoor and outdoor sites. Built-in sensors cover the essentials, and hot-swappable gas sensor cartridges and a differential-pressure option add more.
Built-inRelative HumidityParticle Count (by size)Gas 1
Free: one more gas sensor cartridge
Gas 2
Free: one more gas sensor cartridge
MultiSense
Free: a MultiSense, stock or built to order
Expansion
Aethair Diff. Pressure
Differential PressureA gauge sensor reads 0–10 kPa, with the higher-pressure side connected to its port.
Also measures 11 more
Dew PointHeat IndexIlluminance / LightPM1PM10PM2.5Total PM / Mass Conc.Barometric PressureEquivalent Continuous Level (Leq)Sound Pressure Level (SPL)Air Temperature
Who measures each parameter
| Parameter | Aethair PRO |  Aethair IAQ |  External |
|---|---|---|---|
| Differential Pressure | Diff. Pressure cartridge | — | — |
| Particle Count (by size) | Built in | Built in | 1 instrument via Thiamis |
| Relative Humidity | Built in | Built in | 12 instruments via Thiamis |
Devices
Devices That Cover USP 797
How much of this standard one Aethair monitor covers, followed by the third-party instruments in the sensor catalog that measure its parameters. Each connects to Environet through a Thiamis gateway, which adds whatever the monitor leaves out.
Aethair monitors
Aethair PRO Built in + Aethair Diff. PressureCovers all 3Aethair IAQ Built-in sensors2 of 3: Particle Count, Relative HumidityCovers part of it (combine on one Thiamis)
Solutions
Solutions Judged Against USP 797
Healthcare Air Monitoring
Clinical air quality, pressurization, and patient safety
Article Library
Articles on USP 797
Hospital Air Quality Monitoring: Standards by Space
Hospital air quality standards from ASHRAE 170 and The Joint Commission explained, plus what to measure in operating rooms, isolation rooms, and labs.
ASHRAE 170 Requirements and Which Edition Applies to You
ASHRAE 170 requirements explained: what the standard sets, which edition your facility is held to, what changed in 2025, and how each value gets verified.
Questions
USP 797 FAQ
What pressure differential does USP 797 require?
At least 0.020 inches of water column (about 5 Pa) positive pressure in the buffer room relative to adjacent, less clean areas.
What ISO classes does USP 797 use?
ISO Class 5 for the primary engineering control where compounding takes place, inside an ISO Class 7 buffer room, as defined by ISO 14644-1.
What humidity does USP 797 call for?
Relative humidity in compounding areas held at 60 % or below.
Monitor Against USP 797
Schedule a callBuild a Configuration All standards
A 30-minute call: you tell us about your application, then we demo the solution for it.