--- title: "USP 800 Negative Pressure and Humidity Limits | Aethair" description: "USP <800> limits for hazardous drug rooms: negative pressure of 2.5 to 7.5 Pa, air changes, and humidity, with who it applies to and a recommended setup." url: https://aethair.io/standards/usp_800/ --- Compliance · United States Pharmacopeia # USP General Chapter <800>: hazardous drugs, handling in healthcare settings Indoor: hazardous drug compounding (USA) **USP General Chapter <800>**, Hazardous Drugs — Handling in Healthcare Settings, protects workers who prepare and handle hazardous drugs such as chemotherapy agents. Sterile hazardous drugs are compounded in a containment secondary engineering control (C-SEC): an externally vented room with at least 12 air changes per hour that must hold **negative pressure of 0.01 to 0.03 inches of water column (about 2.5 to 7.5 Pa) relative to all adjacent areas at all times**. Relative humidity is held at **60 % or below**, as in USP <797>. [Schedule a call](https://calendly.com/d/ctdd-mkr-v9v/aethair-demo-website) [Configure USP 800 Monitoring](https://aethair.io/build/?params=differential_pressure,humidity) At a glance **United States Pharmacopeia** Indoor: hazardous drug compounding (USA) 2 parameters · 2 limit values [Differential Pressure](https://aethair.io/parameters/differential_pressure/) [Relative Humidity](https://aethair.io/parameters/humidity/) 1 device measures them all - **Aethair PRO** Aethair Diff. Pressure [Official text from United States Pharmacopeia](https://www.usp.org/compounding/general-chapter-hazardous-drugs-handling-healthcare) Limit values ## USP 800 Limit Values Every value United States Pharmacopeia publishes for the 2 parameters below, with its averaging period, as the standard states it. [**Differential Pressure** Meteorology](https://aethair.io/parameters/differential_pressure/) **2.5–7.5 Pa** *Negative range, containment room (C-SEC)* 0.01 to 0.03 in. w\.c. negative relative to all adjacent areas, at all times [**Relative Humidity** Meteorology](https://aethair.io/parameters/humidity/) **60 %** *Maximum, compounding areas* Who it applies to ## Who Must Comply Every healthcare setting that receives, stores, compounds, dispenses, or administers hazardous drugs: hospital and retail pharmacies, infusion centers, oncology clinics, and veterinary practices, as enforced by state boards of pharmacy. Monitoring ## How Monitoring Demonstrates Compliance The negative pressure range is the requirement most often monitored continuously, because a room that drifts positive pushes hazardous drug residue outward. A continuous differential pressure record with alarms, together with temperature and humidity, documents that the containment held between the periodic certifications. [Customize this configuration](https://aethair.io/build/?params=differential_pressure,humidity) ### Who measures each parameter | Parameter | Aethair PRO | Aethair IAQ | External | | - | - | - | - | | [Differential Pressure](https://aethair.io/parameters/differential_pressure/) | Diff. Pressure cartridge | — | — | | [Relative Humidity](https://aethair.io/parameters/humidity/) | Built in | Built in | [12 instruments](https://aethair.io/parameters/humidity/) via Thiamis | Devices ## Devices That Cover USP 800 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. Pressure Covers both](https://aethair.io/products/pro/) [**Aethair IAQ** Built-in sensors 1 of 2: Relative Humidity](https://aethair.io/products/iaq/) Covers part of it (combine on one Thiamis) [**Fluke Calibration 1620A DewK** Heat Stress & Comfort 1 of 2: Relative Humidity](https://aethair.io/sensors/fluke-calibration-heat-stress-comfort/) Solutions ## Solutions Judged Against USP 800 ### [Healthcare Air Monitoring](https://aethair.io/solutions/healthcare/) Clinical air quality, pressurization, and patient safety [All solutions](https://aethair.io/solutions/) Article Library ## Articles on USP 800 ### [Hospital Air Quality Monitoring: Standards by Space](https://aethair.io/resources/healthcare-air-quality-monitoring/) 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](https://aethair.io/resources/ashrae-170-requirements/) 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. [All articles](https://aethair.io/resources/) Questions ## USP 800 FAQ What pressure does USP 800 require for a hazardous drug room? Negative pressure of 0.01 to 0.03 inches of water column (about 2.5 to 7.5 Pa) relative to all adjacent areas, at all times. How many air changes does USP 800 require? At least 12 air changes per hour in the containment room, which must be externally vented. How does USP 800 relate to USP 797? [USP 797](https://aethair.io/standards/usp_797/) sets the standards for sterile compounding in general; USP 800 adds the containment requirements for hazardous drugs, including negative pressure.