Summary of Biosafety Levels

Summary of Laboratory Biosafety Levels

BSL	Agents	Special Practicesa	Primary Barrier and Personal Protective Equipmenta	Facilities (Secondary Barriers)a
1	Well-characterized agents not known to consistently cause disease in immunocompetent adult humans and present minimal potential hazard to laboratory personnel and the environment.	Standard Microbiological Practices	No primary barriers required; protective laboratory clothing; protective face, eyewear, as needed	Laboratory doors; sink for handwashing; laboratory bench; windows fitted with screens; lighting adequate for all activities
2	Agents associated with human disease and pose moderate hazards to personnel and the environment	Limited access; occupational medical services including medical evaluation, surveillance, and treatment, as appropriate; all procedures that may generate an aerosol or splash conducted in a BSC; decontamination process needed for laboratory equipment	BSCs or other primary containment device used for manipulations of agents that may cause splashes or aerosols; protective laboratory clothing; other PPE, including respiratory protection, as needed	Self-closing doors; sink located near exit; windows sealed or fitted withscreens; autoclave available
3	Indigenous or exotic agents; may cause serious or potentially lethal disease through the inhalation route of exposure	Access limited to those with need to enter; viable material removed from laboratory in primary and secondary containers; opened only in BSL-3 or ABSL-3 laboratories; all procedures with infectious materials performed in a BSC	BSCs for all procedures with viable agents; solid front gowns, scrubs, or coveralls; two pairs of gloves, when appropriate; protective eyewear, respiratory protection, as needed	Physical separation fromaccess corridors; access throughtwo consecutive self-closing doors;hands-free sink near exit; windows aresealed; ducted air ventilation systemwith negative airflow into laboratory;autoclave available, preferably inlaboratory
4	Dangerous and exotic agents that pose high individual risk of aerosol-transmitted laboratory infections and life-threatening disease that are frequently fatal, for which there are no vaccines or treatments; and related agents with unknown risk of transmission	Clothing change before entry; daily inspections of essential containment and life support systems; all wastes decontaminated prior to removal from laboratory; shower on exit	BSCs for all procedures with viable agents; solid front gowns, scrubs, or coveralls;b gloves;b  full-body, air-supplied, positive pressure suitc	Entry sequence; entry through airlock with airtight doors;c walls, floors, ceilings form sealed internal shell; dedicated, non-recirculating ventilation system required; double-door, pass-through autoclave required

1. Each successive BSL contains the recommendations of the preceding level(s) and the criteria in the cell.
2. Applies to Cabinet Laboratory
3. Applies to Suit Laboratory

CDC/NIH Biosafety in Microbiological and Biomedical Laboratories; 6th Edition