Sterile compounding of HDs must be completed in a C-PEC that provides ISO class what or better air quality?

• A. ISO class 3
• B. ISO class 4
• C. ISO class 5
• D. ISO class 7

Answer: (C)

The main idea is the level of air cleanliness required at the work surface of the containment device used for sterile hazardous drug compounding. For sterile HD work, the primary engineering control (the C-PEC) must deliver ISO class 5 air quality at the work area, or a higher standard if available. This level minimizes particulates and potential contaminants that could compromise the sterility of the preparation and protect staff from exposure. ISO 7 is not clean enough for direct HD compounding, while ISO 3 or 4 would be cleaner but the baseline requirement specified is ISO 5. In practice, aiming for ISO 5 or better at the C-PEC is the standard, with surrounding rooms often maintained at ISO 7 or better.