Stanford University

Summary of Recommended Biosafety Levels for Infectious Agents

How to use this tool

This tabel is taken from the U.S. Department of Health and Human Services, Centers for Disease Control and Prevention and National Institutes of Health. Biosafety in Microbiological and Biomedical Laboratories (BMBL) 4th Edition. Washington: GPO, May 1999.

BSL Agents Practices Safety Equipment (Primary Barriers) Facilities (Secondary Barriers)
BSL Agents Practices Safety Equipment (Primary Barriers) Facilities (Secondary Barriers)
1 Not known to consistently cause disease in healthy adults Standard Microbiological Practices None required Open bench top sink required
2 Associated with human disease hazard = percutaneous injury, ingestion, mucous membrane exposure BSL-1 practice plus:

  • Limited access
  • Biohazard warning signs
  • “Sharps” precautions
  • Biosafety manual defining any needed waste decontamination or medical surveillance policies
Primary barriers = Class I or II BSCs or other physical containment devices used for all manipulations of agents that cause splashes or aerosols of infectious materials; PPEs: laboratory coats; gloves; face protection as needed BSL-1 plus:
Autoclave available
3 Indigenous or exotic agents with potential for aerosol transmission; disease may have serious or lethal consequences BSL-2 practice plus:

  • Controlled access
  • Decontamination of all waste
  • Decontamination of lab clothing before laundering
  • Baseline serum
Primary barriers = Class I or II BCSs or other physical containment devices used for all open manipulations of agents; PPEs: protective lab clothing; gloves; respiratory protection as needed BSL-2 plus:

  • Physical separation from access corridors
  • Self-closing double-door access
  • Exhausted air not recirculated
  • Negative airflow into laboratory
4 Dangerous/exotic agents which pose high risk of lifethreatening disease aerosol-transmitted lab infections; or related agents with unknown risk of transmission BSL-3 practices plus:

  • Clothing change before entering
  • Shower on exit
  • All material decontaminated on exit from facility
Primary barriers = 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 decon systems
  • Other requirements outlined in the text
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