Which Biosafety Level requires all manipulations of biohazards to take place within biological safety cabinets?

Biosafety Level 3 (BSL3) is characterized by the requirement that all manipulations of potentially harmful agents, such as infectious microorganisms, be conducted within biological safety cabinets. This is essential because BSL3 agents can cause serious or potentially lethal disease through inhalation, necessitating enhanced containment measures to protect laboratory personnel, the community, and the environment.

In a BSL3 facility, the biological safety cabinets provide a necessary barrier to contain aerosols, thereby reducing the risk of exposure during laboratory procedures. This level of biosafety also includes additional protective measures such as access control and specialized ventilation systems to maintain stringent containment.

In contrast, BSL1 allows for basic precautions with minimal risk agents that are not known to consistently cause disease in healthy adults, and thus may not require the restrictive use of biological safety cabinets. BSL2 involves work with moderate-risk biological agents, where laboratory practices are more stringent, and while biological safety cabinets are recommended for certain procedures, they are not universally required. BSL4, the highest level, demands the most extensive safety measures, including full-body, air-supplied suits and highly controlled environments, but it specifically mandates that work with the most dangerous agents occurs within specialized facilities rather than just biological safety