How many air exchanges per hour are typically required in an operating room to maintain air quality?

• A. 5 to 10
• B. Approximately 15 to 20 air exchanges per hour
• C. 25 to 30
• D. 40 to 50

Answer: (B)

Maintaining air quality in an operating room hinges on how often the room air is refreshed, measured as air exchanges per hour. The standard target is approximately 15 to 20 air exchanges per hour. This rate provides enough dilution and removal of airborne contaminants—like surgical smoke, dust, and anesthetic gases—while helping maintain a positive pressure environment to protect the sterile field. If the rate is too low, contaminants can accumulate and increase infection risk; if it’s excessively high, energy and noise costs rise without added benefit. The other options are outside the typical baseline: too few exchanges don’t clean the air quickly enough, while the higher numbers are unnecessarily intense for most ORs.