Table 1.

CDC Summary of Recommended Biosafety Levels for Infectious Agentsa,b

Biosafety level	Agent characteristics	Practices	Safety equipment (primary barriers)c	Facilities (secondary barriers)
BSL‐1	Not known to consistently cause disease in healthy adults	Standard microbiological practices	None required	Open benchtop sink
BSL‐2	Associated with human disease, hazard from percutaneous injury, ingestion, mucous membrane exposure	Standard microbiological practices Limited access Biohazard warning signs “Sharps” precautions Biosafety manual defining any needed waste decontamination or medical surveillance policies	Class I or II biosafety cabinets (BSCs) or other physical containment devices used for all manipulations of agents that cause splashes or aerosols of infectious materials Laboratory coats and gloves Face protection as needed	Open benchtop sink Autoclave
BSL‐3	Indigenous or exotic agents with potential for aerosol transmission; disease may have serious or lethal consequences	All BSL‐2 practices Controlled access Decontamination of all waste Decontamination of laboratory clothing before laundering Baseline serum	Class I or II BSCs or other physical containment devices used for all open manipulations of agents Protective lab clothing and gloves Respiratory protection as needed	Open benchtop sink Autoclave Physical separation from access corridors Self‐closing, double‐door access Exhausted air not recirculated Negative airflow into laboratory
BSL‐4	Dangerous/exotic agents which pose high risk of life‐threatening disease; aerosol‐transmitted lab infections; or related agents with unknown risk of transmission	All BSL‐3 practices Clothing change before entering Shower on exit All material decontaminated on exit from facility	All procedures conducted in Class III BSCs, or Class I or II BSCs in combination with full‐body, air‐supplied, positive pressure personnel suit	BSL‐3 plus: Separate building or isolated zone Dedicated supply and exhaust, vacuum, and decontamination systems Other requirements outlined in the text

^aAdapted from Biosafety in Microbiological and Biomedical Laboratories, 5th Ed., available online at http://www.cdc.gov/od/ohs/biosfty/bmbl5/bmbl5toc.htm.

^bThe practices, and primary and secondary barriers required for a given biosafety level include those of the all lower levels, as well as the additional required practices, equipment, and/or facilities described for the BSL in question.

^cSee http://www.cdc.gov/od/ohs/biosfty/bmbl5/sections/AppendixA.pdf for more information concerning biological safety cabinets (BSCs).

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