What ISO Class is required for the anteroom?

• A. Class 3
• B. Class 5
• C. Class 9
• D. Class 7

Answer: (D)

Air cleanliness is defined by ISO classifications, and the anteroom acts as a buffer between the general, less controlled area and the ISO 5 sterile compounding space. Setting the anteroom to ISO Class 7 provides enough control to limit particle ingress into the sterile area while remaining practical for traffic, air changes, and door sequencing. It supports the pressure relationships and airflow management that minimize contamination when people and materials pass through. If the space were far cleaner than this, it would be unnecessarily stringent for a buffering zone; if it were much dirtier, it would risk compromising the sterile area. Therefore, ISO Class 7 is required for the anteroom.