Which of the following correctly describes anteroom requirements?

• A. Fixed walls, positive pressure, at least 30 ACPH
• B. Fixed walls, negative pressure, at least 30 ACPH
• C. Flexible walls, positive pressure, at least 60 ACPH
• D. Fixed walls, no specific ACPH requirement

Answer: (A)

Ananterooms act as a controlled buffer space between the general area and the hazardous drug compounding area, helping maintain containment and control of airborne contaminants. The space needs a defined, solid boundary so that it can be reliably cleaned, sealed, and maintained under the intended pressure relationships. Fixed walls are essential for this reliability; flexible or partial enclosures would leak air and compromise containment.

Having the ante room under positive pressure relative to surrounding spaces helps create air movement that protects the more sensitive areas downstream. When doors are opened, air tends to flow from higher-pressure areas to lower-pressure areas, so a positively pressurized ante room helps push air outward rather than drawing contaminated air in from adjacent spaces, contributing to containment of hazardous drug vapors or aerosols.

A minimum of 30 air changes per hour provides enough turnover of air to dilute and remove any contaminants that may be generated in the ante room and to support the established pressure differentials. It balances effectiveness with practicality and avoids unnecessary energy use that higher change rates would require.

Flexible walls would not maintain the necessary seal or pressure relationships; negative pressure in the ante room would draw contaminants in rather than helping contain them; and omitting an ACPH requirement or using a much higher rate than needed would either risk poorer control or unnecessary energy expenditure.