What temperature range should a hot air oven be maintained at to achieve sterility?

• A. 100-120 C
• B. 150-180 C
• C. 50-80 C
• D. 200-250 C

Answer: (B)

Dry heat sterilization relies on high, sustained heat to inactivate microorganisms by denaturing proteins and oxidizing cellular components. Because dry heat is less efficient than moist heat, the temperature needs to be higher and maintained longer. A hot air oven is typically kept at about 150–180 C to achieve sterility, with the exact time adjusted to the load and guidelines. Temperatures in the 100–120 C range are too low for reliable sterilization in a practical cycle, 50–80 C is far below what’s needed, and 200–250 C is unnecessarily harsh and can damage instruments. Maintaining 150–180 C provides the appropriate balance to sterilize safely and effectively.