Containment secondary engineering control
Under USP 800, the room that houses a containment primary engineering control for hazardous drugs, abbreviated C-SEC. It must be externally vented, physically separated, held negative between 0.01 and 0.03 inches of water column, and supplied with the air changes the chapter sets.
Also called C-SEC, hazardous drug buffer room, negative pressure compounding room
What is a containment secondary engineering control?
A containment secondary engineering control, or C-SEC, is the negative, externally vented room USP 800 requires around a hazardous drug cabinet. A nonsterile C-SEC needs at least 12 air changes per hour and a sterile one at least 30, both between 0.01 and 0.03 inches of water column negative.
Containment secondary engineering control: how it works
The containment cabinet keeps drug residue inside at the work surface, and the C-SEC is the second barrier around it. Holding the room negative makes every gap leak inward, so residue that escapes the cabinet stays in the room, and external venting sends the room's air outdoors instead of back into a building air system. A sterile C-SEC adds HEPA-filtered supply to hold ISO 7 and is entered through a positive ISO 7 anteroom.
Where you meet the term
- In a hospital or specialty pharmacy that compounds chemotherapy and other hazardous drugs.
- In a USP 800 facility assessment, which checks air changes, pressure, and external venting for the room.
- In an HVAC design where the negative buffer room and its positive anteroom have to fit one pressure plan.
How to check it
- Read the room pressure monitor. The monitor at the C-SEC door should show the room negative within 0.01 to 0.03 inches of water column with the doors closed. Owner check
- Verify exhaust and air changes at certification. A certifier measures supply and exhaust airflow, confirms the room is externally vented, and checks its pressure against the USP 800 range. Technician
Containment secondary engineering control: what it is not
- A C-SEC is not a positive USP 797 buffer room with a hazardous drug hood added. It runs negative and externally vented, with a different pressure plan.
- A C-SEC is not the same as a C-SCA. A containment segregated compounding area has no ISO classification and limits sterile preparations to short beyond-use dates.
Containment secondary engineering control questions
What is a C-SCA?
A containment segregated compounding area is a separate, negative, externally vented room with at least 12 air changes per hour but no ISO classification. It can house a containment cabinet, and sterile preparations made there carry the short beyond-use dates USP 797 assigns.
Can a C-SEC share an exhaust system with other rooms?
USP 800 requires external venting and rules out recirculation to the building. Whether a shared exhaust system is acceptable is settled by showing that it holds each room's negative pressure and prevents backflow between rooms, with the certifier and the state board.
Does every C-SEC need an ISO 7 anteroom?
A sterile C-SEC is entered through an ISO 7 anteroom held at least 0.02 inches of water column positive to adjacent unclassified areas. A nonsterile C-SEC must be separated, negative, and externally vented but does not carry that ISO 7 anteroom requirement.
Where this definition comes from
Written from standards body publication material held in the HVAC Bench evidence record. Where a document limits a definition to certain models, that limit is repeated here rather than generalised across a brand.
- General Chapter 800, Hazardous Drugs, Handling in Healthcare SettingsEngineering controls for hazardous drugs: storage rooms and nonsterile containment secondary engineering controls externally vented, at least 12 air changes per hour, and negative between 0.01 and 0.03 inches of water column relative to adjacent areas; sterile hazardous drug buffer rooms of ISO 7 air quality with HEPA-filtered supply, externally vented, at least 30 air changes per hour, and negative between 0.01 and 0.03 inches of water column; an ISO 7 anteroom with at least 30 air changes per hour and at least 0.02 inches of water column positive to adjacent unclassified areas; and a containment segregated compounding area externally vented with at least 12 air changes per hour at the same negative pressure range.
- General Chapter 797, Pharmaceutical Compounding, Sterile Preparations2023 revision, official 1 November 2023, for sterile compounding: at least 30 air changes per hour of HEPA-filtered supply in ISO 7 buffer rooms and anterooms and at least 20 in ISO 8 rooms, with at least 15 of them supplied by the HVAC system through HEPA filters; a minimum positive pressure differential of 0.020 inches of water column between the buffer room and anteroom and between the anteroom and unclassified space, monitored continuously; rooms maintained at 20 degrees Celsius or cooler and 60 percent relative humidity or below; and certification of primary and secondary engineering controls every six months.