How many air exchanges per hour are typically maintained in the operating room?

• A. 5-10 per hour
• B. 25-30 per hour
• C. 15-20 per hour
• D. 1-5 per hour

Answer: (C)

Air exchange rate is how many times the room’s air is replaced in an hour, and it’s chosen to keep the environment clean without creating uncomfortable drafts or wasting energy. In an operating room, you want enough turnover to dilute and remove airborne contaminants, including surgical smoke and anesthetic vapors, while maintaining stable temperature and humidity and preserving the sterile field. The typical target is a middle range: it’s high enough to achieve effective dilution but not so high that it causes unnecessary energy use or drafts. That balance is why the mid-range option is the best choice. Lower rates wouldn’t dilute contaminants quickly enough, and higher rates aren’t necessary in most general ORs and can introduce other drawbacks.