TABLE 2-1Recommended Practices, Safety Equipment, and Facilities for Biosafety Levels 1-4

BSLAgentsPracticesPrimary Barriers and Safety EquipmentFacilities (Secondary Barriers)
1Not known to consistently cause diseases in healthy adultsStandard microbiological practicesNone requiredLaboratory bench and sink required
2Agents associated with human disease
Routes of transmission include percutaneous injury, ingestion, mucous membrane exposure
BSL-1 practices 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 biosafety cabinets (BSCs) or other physical containment devices used for all manipulations of agents that cause splashes or aerosols of infectious materials
Personal protective equipment (PPEs): Laboratory coats, gloves, face protection as needed
BSL-1 plus:
  • Autoclave available
3Indigenous or exotic agents with potential for aerosol transmission
Disease may have serious lethal consequences
BSL-2 practices plus:
  • Controlled access
  • Decontamination of all waste
  • Decontamination of laboratory clothing before laundering
  • Baseline serum
Primary barriers: Class I or II BSCs or other physical containment devices used for open manipulation of agents
PPEs: Protective laboratory clothing, gloves, respiratory protection as needed
BSL-2 plus:
  • Physical separation from access corridors
  • Self-closing, double-door access
  • Exhaust air not recirculated
  • Negative airflow into laboratory
4Dangerous/exotic agents pose high risk of life threatening disease
Aerosol-transmitted laboratory infections have occurred; related agents with unknown risk of transmission
BSL-3 practices plus:
  • Clothing change before entering
  • Shower on exit
  • All material decontaminated upon 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 suitBSL-3 plus:
  • Separate building or isolated zone
  • Dedicated supply and exhaust, vacuum, and decontamination systems
  • Additional requirements


From: 2, The Current Regulatory Environment

Cover of Responsible Research with Biological Select Agents and Toxins
Responsible Research with Biological Select Agents and Toxins.
National Research Council (US) Committee on Laboratory Security and Personnel Reliability Assurance Systems for Laboratories Conducting Research on Biological Select Agents and Toxins.
Washington (DC): National Academies Press (US); 2009.
Copyright © 2009, National Academy of Sciences.

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