Biosafety cabinets (BSCs) are one type of biocontainment equipment used in biological laboratories to provide personnel, environmental, and product protection. Most BSCs (e.g., Class II and Class III) use high efficiency particulate air (HEPA) filters in both the exhaust and supply system to prevent exposure to biohazards.
There are several designs of biosafety cabinets which provide different levels of protection to the worker and to the research material. There are three classes of biosafety cabinets designated in the United States: Class I, Class II, and Class III. Class I biosafety cabinets are infrequently used and provide personnel and environmental protection but no product protection. Class II and Class III cabinets provide personnel, environmental, and product protection. Class II biosafety cabinets are widely used in biological research laboratories and are differentiated into types such as A1, A2, B1, or B2.The classification for the majority of biosafety cabinets used in the United States is Class II Type A2. The naming system given here is the one used in the United States and in CDC/NIH guidance Biosafety in Microbiological and Biomedical Laboratories Appendix A. Other naming conventions have been used in the past or in other countries.
Laminar flow hoods (e.g., “clean benches”) are not biosafety cabinets. Laminar flow hoods provide a clean or sterile area to protect the work product, but discharge air towards the worker. In work with infectious agents, toxins, or cultures, use of laminar flow hoods may expose the worker to the biological material. Likewise, chemical fume hoods cannot be used in place of biosafety cabinets. Chemical fume hoods are used to protect personnel from chemical exposure and are not appropriate for work involving infectious agents or toxins. Biosafety cabinets must be inspected by trained personnel on a regular basis and be “certified” as safe for work involving infectious agents or toxins.