What are some characteristics of microbes and infectious agents that would require handling in a BSL-3 laboratory?

The microbes would be toxic or have potential to cause a lethal disease. Highly infectious, like Mycobacterium tuberculosis which is readily and highly transmitted by inhalation and aerosol means. Can contaminate the environment. The treatment or prophylactic measures are expensive and inefficient.

BSL or the biological safety levels refers to an array of protections consigned to autoclave-associated activities, which occurs in specific biological labs. The BSL-3 refers to the biosafety level that generally comprises work on microbes, which are either exotic or indigenous and can result in potentially or extreme lethal disease via inhalation. The examples of microorganisms that are handled in BSL=3 comprises West Nile virus, yellow fever, and the bacteria, which leads to tuberculosis.