Which of the following is NOT a characteristic of a positive pressure room?

• A. Prevents contaminated air from entering
• B. Air can leave without circulating back in
• C. Maintains a lower pressure than surrounding areas
• D. Pressure is higher in treated area

Answer: (C)

The characteristic that is not true of a positive pressure room is that it maintains a lower pressure than surrounding areas. In reality, a positive pressure room is designed to be at a higher pressure compared to the areas outside of it. This higher pressure helps to prevent contaminated air from entering the sterile environment, ensuring that the air inside is cleaner and helps to maintain the sterility necessary for compounding sterile preparations.

In a positive pressure setting, air flows out of the room when doors or hatches are opened, and it is not designed to allow air to easily circulate back in from adjacent spaces. This is part of its function to create a protective barrier against contaminants. The air quality is also closely monitored and often filtered to maintain the required sterility levels, emphasizing the importance of maintaining the pressure differential compared to outside environments. Therefore, the correct concept is that the pressure must be higher inside the positive pressure room to effectively protect against contamination.