Hot air ovens are dry heat sterilizers used for sterilizing heat-stable materials, particularly glassware, powders, and anhydrous oils, that cannot be effectively sterilized by moist heat (steam) or would be damaged by it. They work by circulating hot air at very high temperatures, typically between 160°C and 190°C, for extended periods (e.g., 1-2 hours) to achieve sterilization. The dry heat mechanism involves the denaturation of proteins and oxidative damage to microbial components. While effective for specific materials and preventing corrosion of certain metal instruments, hot air ovens are slower and less efficient than steam autoclaves and do not readily penetrate porous materials. They play a niche but important role in sterilization processes, particularly in laboratories and specialized medical settings where dry heat is the preferred or only suitable method for certain types of materials.