Summary of Recommended Biosafety Levels for Activities in Which Experimentally or Naturally Infected Vertebrate Animals Are Used

​​Biosafety Level Agents​ Practices​ ​Safety Equipment (Primary Barriers) Facilities (Secondary Barriers)​

Not known to consistently cause disease in healthy human adults.

Standard animal care and management practices, including appropriate medical surveillance programs.

As required for normal care of each species.

Standard animal facility; No recirculation of exhaust air, Directional air flow recommended; Handwashing sink recommended.


Associated with human disease. Hazard: percutaneous exposure, ingestion, mucous membrane exposure.

ABSL-1 practices plus:  Limited access; Biohazard warning signs;  Sharps precautions; Biosafety manual;  Decontamination of all infectious wastes and of animal cages prior to washing.

ABSL-1 equipment plus primary barriers: containment equipment appropriate for animal species. 

PPE: laboratory coats, gloves, face and respiratory protection as needed.

ABSL-1 facility plus:  Autoclave available; Handwashing sink available in the animal room;  Mechanical cage washer used.


Indigenous or exotic agents with potential for aerosol transmission; disease may have serious health effects.

ABSL-2 practices plus:  Controlled access;  Decontamination of clothing before laundering; Cages decontaminated before bedding removed; Disinfectant footbath as needed.

ABSL-2 equipment plus:  Containment equipment for housing animals and cage dumping activities Class I or II BSCs available for manipulative procedures (inoculation, necropsy) that may create infectious aerosols. PPEs: appropriate respiratory protection.

ABSL-2 facility plus:  Physical separation from access corridors; Self-closing, double-door access; Sealed penetrations;  Sealed windows; Autoclave available in facility.


Dangerous/exotic agents that pose high risk of life threatening disease; aerosol transmission, or related agents with unknown risk of transmission.

ABSL-3 practices plus:  Entrance through change room where personal clothing is removed and laboratory clothing is put on; shower on exiting; All wastes are decontaminated before removal from the facility.

ABSL-3 equipment plus:  Maximum containment equipment (i.e., Class III BSC or partial containment equipment in combination with full body, air-supplied positive-pressure personnel suit) used for all procedures and activities.

ABSL-3 facility plus:  Separate building or isolated zone; Dedicated supply and exhaust, vacuum and decontamination systems; Other requirements outlined in the text.​