| BSL | Agents | Practices | Safety Equipment
(Primary Barriers) |
Facilities (Secondary Barriers) |
| 1 | Not known to cause disease in healthy adults | Standard Microbiological Practices | None required | Open bench top sink required |
| 2 | Associated with human disease, hazard = auto-inoculation, 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-1plus: 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 lab clothing before laundering -Baseline serum | Primary barriers=Class I or II BCSs or other physical containment devices used for all manipulations of agents; PPEs" protective lab clothing; gloves; respiratory protection is 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/exhaust, vacuum, and decon systems -Other requirements outlined in the text |