BIOLOGICAL SAFETY CABINETS must be used when additional protection of the user and the environment is also required. Biological safety cabinets come in several classes (I, II, and III) that offer varying levels of protection from hazardous or contagious materials. For all classes of biological safety cabinet, the air is HEPA- filtered before being released as exhaust.

Class I Bio Safety Cabinet: - protects the user and the environment, but not the product as air is pulled into the cabinet and exhausted (usually out the top) out away from the user.

Class II Biological Safety Cabinets: - fall into four subcategories. Type - A1, A2,- B1, B2 - All of which protect the product or specimen, the user and the environment from contamination. This is especially crucial for applications that require sterile or particulate-free conditions - such as cell culture experiments, drug preparations, or in toxicology when working with fumes and gases is required. All types of Class II biological safety cabinet have HEPA filters at their air supply and exhaust points. However, the Class II sub types differ in the amount of air that is re-circulated within the cabinet versus exhausted outward.

Class III Biological Safety Cabinets: - also known as Bio glove boxes, provides - maximum protection for work in biosafety level 4 containment labs. A class III bio safety cabinet is crucial for working with any bio-safety level 4 agents, or other dangerous materials, such as aerosols of pathogens or toxins. Class III bio-safety cabinet has two HEPA filters in the exhaust system for additional environmental protection. Manipulations within the chamber of the Bio glove box are performed with built-in arm-length rubber gloves.