The selection of the class or type of BSC depends on the degree or nature of the hazard associated with the experiment, the aerosol-producing potential of the laboratory procedures, and the requirement to protect the experiment from airborne contamination. EHS must review and approve all purchases and installations of biological safety cabinets. This ensures selection of the proper cabinet for the intended use, and installation for proper functioning, maintenance, and certification.

Table 16-1 provides a summary and comparison of BSC characteristics and application. In general, the Class II, type A1, A2 BSC (non-ducted) is sufficient when the work involves infectious agents and cell culture work in the absence of volatile toxic chemicals and radionuclides. When small amounts of volatile chemicals or radionuclides are involved, the Class II, type B (types B1, B2) is more appropriate. Select a Class III cabinet when the work involves the handling of high-risk microbiological agents, concentrated amounts of carcinogens, or highly toxic chemicals.

NSF International – The Public Health and Safety Company™ lists the models of the various cabinet manufacturers that meet its standard criteria described in NSF Standard No. 49 for “Class II (laminar flow) Biohazard Cabinetry”. This standard includes design and construction requirements as well as performance specifications such as vibration; temperature rise; noise level, and personnel, product, and cross-contamination protection determined by a spore aerosol challenge. Selection of an NSF-approved model assures the purchaser that the model meets minimum construction and performance standards.

Most manufacturers offer user options such as ultraviolet (UV) or germicidal lights. UV lights are not recommended by NSF 49, but if installed they must be cleaned weekly to remove dust which can reduce their germicidal effectiveness. They must also be installed in a manner that does not reduce the required performance of the cabinet. Take precautions to prevent exposure of the eyes and skin to damaging effects of UV light. Keep the protective sashes in place, and do not place your hands or arms within a cabinet when the UV (purple) lamp is on. Turn off UV lamps when the room is occupied.

To accommodate special applications, the manufacturer can modify the design of biological safety cabinets. Examples include altering the front sash to accommodate microscope eyepieces, or adapting the work surface to include a centrifuge or animal waste handling capabilities.