Which Biosafety Level requires at least two-door separation and verification of air flow direction?

Biosafety Level 3 (BSL3) requires at least two-door separation and verification of air flow direction as part of its enhanced safety measures. This level of containment is necessary for working with pathogens that can cause serious or potentially lethal diseases through inhalation. The two-door separation design helps create an airlock, minimizing the risk of exposure to infectious agents during a transfer of materials and personnel in and out of the laboratory. Furthermore, the verification of air flow direction is crucial to ensure that air is drawn into the laboratory and filtered before it can be released outside, preventing any escape of contaminants into the outside environment. This level of precautions is essential to protect laboratory personnel and the surrounding community from airborne biological hazards.