Chemical vapor sterilization uses which medium to achieve sterilization?

• A. Moist heat under pressure
• B. Dry heat
• C. Chemical vapors under pressure
• D. Ethylene oxide gas

Answer: (C)

Chemical vapor sterilization uses chemical vapors under pressure to kill microorganisms. This method typically involves a formaldehyde-based vapor mixed with methanol and water that is heated and pressurized inside a sealed chamber, allowing the vapor to penetrate all surfaces of instruments. It’s distinct from moist heat under pressure (steam autoclaves) and from dry heat (hot air), and it’s separate from ethylene oxide gas sterilization, which uses EO gas rather than a chemical vapor mixture under pressure. So the medium driving the process is chemical vapors under pressure.