What is the most common gas used to sterilize instruments sensitive to temperatures higher than 60 degrees C?

• A. Formaldehyde
• B. Hydrogen peroxide
• C. Ethylene oxide
• D. Ozone

Answer: (C)

Gas sterilization lets you kill microbes on instruments that would be damaged by heat. Ethylene oxide is the most commonly used gas for this purpose because it is effective at low temperatures and can penetrate complex equipment and packaging, sterilizing many materials that can’t tolerate high heat. It typically runs at about room to moderate temperatures (below 60°C) with controlled humidity and requires an aeration step to remove residual gas after the cycle. Other gases like formaldehyde (toxic and less favored today), hydrogen peroxide (used in alternative low-temp methods but not as universally established), and ozone (less reliable for standard sterilization of medical devices) don’t match the broad, proven applicability of ethylene oxide for heat-sensitive instruments.