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Each BSL has its own corresponding requirements for the laboratory facilities (Table 2).

Table 2. Summary of laboratory facilities for BSL 1 – 4.
BSL Agents Practices Safety Equipment (Primary Barriers) Facilities (Secondary Barriers)
1 Not associated with disease in healthy adults Standard Microbiological Practices As needed to allow for good microbiological practices
  • 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 BSC or other physical containment devices used for all manipulations of agents that cause splashes or aerosols of infectious materials
PPE: 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 practices plus:
  • Controlled access
  • Decontamination of all waste
  • Decontamination of lab clothing before laundering
  • Baseline serum
 Primary barriers: Class I or II BSC or other physical containment devices used for all open manipulations of agents
PPE: 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 a Class III BSC, or Class I or II BSC 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 of the BMBL

The physical requirements described in Table 2 will be used in conjunction with additional protective mechanisms (see Chapter 7) to achieve personnel and environmental safety.