Which compounding environment must be externally vented?

The requirement for an externally vented compounding environment specifically applies to sterile hazardous drug compounding. This is due to the nature of hazardous drugs, which can pose significant health risks to both patients and healthcare workers. An externally vented environment, such as a Class II biological safety cabinet, ensures that harmful airborne contaminants are effectively exhausted from the work area, minimizing the risk of exposure during preparation and compounding processes. Proper ventilation is crucial to maintain safety standards when handling hazardous materials and to protect both the compounders and the environment.

In contrast, non-sterile compounding and non-hazardous compounding do not necessitate the same level of specialized ventilation, as the risks associated with those processes are not as high in terms of airborne contaminants. While safety measures are still important in these environments, they do not require external ventilation like sterile hazardous drug compounding does. Hence, the correct answer highlights the specific need for external venting in the context of sterile hazardous drug preparation.