Biosafety Levels for Infectious Agent Use

Summary of Recommended Biosafety Levels for Infectious Agents
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 and 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 BSCs 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 life-threatening 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

CDC/NIH Biosafety in Microbiological and Biomedical Laboratories; 5th Edition