Why is a clean bench not suitable for containing biohazards?

A clean bench is designed to provide a sterile work environment by directing clean air across the work surface, primarily protecting the materials being manipulated rather than the operator or the surrounding environment. However, this design results in a situation where the air flows directly at the operator, which can potentially expose them to any biohazards present on the work surface. This airflow pattern does not achieve the necessary containment required for handling biohazardous materials, as it does not provide an enclosure to prevent the escape of aerosols or particulate matter that could be hazardous.

In contrast, other types of containment devices, such as biosafety cabinets, create a barrier that protects both the operator and the environment from exposure to potentially infectious agents through proper airflow and containment systems. This is why the design and airflow characteristics of clean benches limit their effectiveness when working with biohazards.