Which Biohazard Level would involve work with agents that can cause serious diseases through inhalation?

Biohazard Level 3 (BSL-3) is designated for laboratories where work is conducted with agents that can cause serious or potentially lethal diseases through inhalation. This level of biohazard containment is specifically crucial for pathogens that are transmitted via airborne routes, posing a significant risk to both laboratory personnel and the surrounding community. Facilities classified under BSL-3 must implement strict access controls, specialized ventilation systems, and extensive safety protocols to protect against airborne exposure and ensure that work with such agents is performed in a secure environment.

In contrast, Biohazard Level 1 (BSL-1) is appropriate for agents that do not generally cause disease in healthy individuals, while BSL-2 involves agents that can cause mild diseases but have limited potential for aerosol transmission. Biohazard Level 4 (BSL-4) pertains to work with highly dangerous and exotic agents that pose a high risk of life-threatening disease through inhalation and for which no vaccine or treatment is available, but this is not the focus of the question. Thus, BSL-3 is the correct classification for dealing with serious diseases transmitted via inhalation.