Biosafety Level Two Plus (BSL-2+) is a term frequently used to describe laboratories where work with microorganisms is conducted in a BSL-2 laboratory with biosafety practices and procedures typically found at BSL-3. The risk assessment process may determine that safety practices over and above those required at BSL-2 are needed for a research project, yet a more complex BSL-3 laboratory facility is not necessary.

This hybrid approach has been used for many years; however, many research institutions still find it challenging to decide when to use this approach and which BSL-3 practices to use. This is due to the fact that it is not a recognized containment level in biosafety guidance documents such as the Centers for Disease Control and Prevention's (CDC) Biosafety in Microbiological and Biomedical Laboratories (BMBL) (U.S. Department of Health and Human Services, 2009) or the National Institutes of Health's (NIH) Guidelines for Recombinant DNA Research (the Guidelines) (NIH, 2011).

This article aims to assist environmental health and safety and biosafety professionals by detailing a practical approach to implementing BSL-2+, including how to identify what projects may benefit from BSL-3 practices and how to modify BSL-3 practices and selected facility requirements for the BSL-2 environment based on institutional needs. In addition, strategies to ensure researchers are properly trained in the use of BSL-3 practices in a BSL-2 laboratory and for developing a project-specific Standard Operating Procedure (SOP) are detailed. Implementing BSL-2+ can be successful when there is a collaboration among the Principal Investigator, Biosafety Officer, Institutional Biosafety Committee, and laboratory personnel.