This text presents information on the design, selection, function and use of biological safety cabinets (BSCs), which are the primary means of containment developed for working safely with infectious microorganisms. Brief descriptions of the facility and engineering concepts for the conduct of microbiological research are also provided. BSCs are only one part of an overall biosafety program which requires consistent use of good microbiological practices. Detailed descriptions of acceptable work practices, procedures, and facilities, described as biosafety levels 1 through 4, are presented in the CDC/NIH publication Biosafety in Microbiological and Biomedical Laboratories (BMBL)⁶.

BSCs are designed to provide personnel, environmental and product protection when appropriate practices and procedures are followed. Three kinds of biological safety cabinets, designated as Class I, II and III have been developed to meet varying research and clinical needs.

High efficiency particulate air (HEPA) filters or ultra-low penetration air (ULPA) filters are used in the exhaust and/or supply systems of biological safety cabinets These filters and their use in BSCs are briefly described in Section II. Section III presents a general description of the special features integrated into biological safety cabinets to provide varying degrees of personnel, product and environmental protection.

Laboratory hazards and risk assessment are discussed in Section IV. Section V presents the laboratorian with work practices, procedures and practical tips to maximize the protection afforded by the most commonly used BSCs. Facility and engineering requirements needed for the operation of each type of BSC are presented in Section VI. Finally, Section VII reviews some of the requirements for routine annual certification of cabinet operation and integrity.

These sections are not meant to be definitive or all-encompassing. Rather, an overview is provided to clarify the expectations, functions and performance of these critical primary barriers. This document has been written for the laboratorian, engineer, manager, or procurement officer who desires a better understanding of each type of cabinet and the rationale for selecting the appropriate BSC to meet specific operational needs.