The concept of "biosafety levels" (BSL) is the basis for laboratory practices designed to prevent laboratory-acquired infections when working with agents belonging to a specific Risk Group. The Centers for Disease Control and Prevention (CDC) and National Institutes of Health (NIH) identifies four levels of containment. Levels are designated in ascending order, by degree of protection provided to personnel, the environment, and the community. Protection is accomplished through proper containment.

Containment is achieved by a combination of laboratory practices and techniques, safety equipment, and facility considerations as outlined by CDC/NIH in Biosafety in Microbiological and Biomedical Laboratories (BMBL). Required containment measures for a given protocol will depend on the results of a risk assessment of the work to be done with an agent of a specific Risk Group. Protocols for all work at Biosafety Level 2 and above must be approved by the Institutional Biosafety Committee (IBC).

See BMBL Section IV for elements of:

• Biosafety Level 1
• Biosafety Level 2
• Biosafety Level 3

Note: Biosafety Levels are not the same as Risk Groups. Please see the Biological Risk Groups web page for more information.