Final answer:
A clean bench is not suitable for containing biohazards because it allows for potential exposure of the operator to contaminants. For biohazard containment, Biological Safety Cabinets are used as they provide proper filtration and containment mechanisms, such as HEPA filters and air flow controls to protect laboratory workers and the environment from exposure.
Step-by-step explanation:
A clean bench is not recommended for containment of biohazards because it directs clean air across the work surface, then pushes air from inside the bench to outside and directly at the operator. This air flow can potentially carry biohazards, such as infectious particles or aerosols, to the person working at the bench, hence providing no containment of these harmful agents. In contrast, Biological Safety Cabinets (BSCs) are designed to protect laboratory workers and the environment from biohazards by using HEPA filters to clean the air, and by containing airborne particles within the cabinet to prevent exposure.
For example, Class I BSCs protect workers by filtering the air before it exits through the building's exhaust system. Class II BSCs use directional air flow and partial barriers for containment. The most secure, Class III BSCs, are used in high-level biosafety labs, such as BSL-4, and include features like a sealed glove box and an air incineration system for the most stringent containment.
It is crucial for laboratory safety that the appropriate type of protective equipment is used based on the biosafety level (BSL) of the pathogens being handled. There are different BSLs that outline the protective measures required in a lab: BSL-1 for non-pathogenic agents, BSL-2 for agents that can cause human disease but have treatments available, BSL-3 for serious or potentially lethal agents that are transmitted through inhalation, and BSL-4 for dangerous/exotic agents which pose a high risk of life-threatening disease.