Biosafety Levels

A biosafety level  (BSL) is a set of biocontainment precautions (i.e. PPE, procedures, equipment, etc.) required to isolate dangerous biological agents in an enclosed laboratory facility. In the United States, the Centers for Disease Control and Prevention (CDC) have specified these levels. The levels (BSL-1,2,3 and 4) are designated in ascending order, by degree of protection provided to personnel, the environment, and the community. Standard microbiological practices are common to all laboatories. Each BSL builds on and includes the biocontainment procedures and precautions employed at lower levels of containment.  Selection of the appropriate BSL is based on a thorough biosafety risk assessment of the biological agents and laboratory procedural hazards that will used in the laboratory. In addition, there are also designated biocontainment levels for laboratory work involving animals.  The levels (ABSL-1,2,3, and 4) are designated in ascending order.

BSL 1 - is suitable for work involving well-characterized agents not known to consistently cause disease in immunocompetent adult humans and present minimal potential hazard to laboratory personnel and the environment. Work is typically conducted on open bench tops using standard microbiological practices. Special containment or facility design is not required, but may be used as determined by appropriate risk assessment. Laboratory personnel receive specific training in the procedures conducted in the laboratory and are supervised by a scientist with training in microbiology or a related science.

BSL 2 - is suitable for work with agents associated with human disease and pose moderate potential hazards to personnel and the environment. BSL-2 differs from BSL-1 primarily because: 1) laboratory personnel receive specific training in handling pathogenic agents and are supervised by scientists competent in handling infectious agents and associated procedures; 2) access to the laboratory is restricted when work is being conducted; and 3)  All procedures in which infectious aerosols or splashes may be created are conducted in BSCs or other physical containment.

BSL 3 - is suitable for work involving indigenous or exotic agents which may cause serious or potentially lethal disease as a result of exposure by inhalation. Laboratory personnel receive specific training in handling pathogenic and potenially lethal agents and must be supervised by scientists competent in handling infectious agents and associated procedures. All procedures involving the manipulation of infectious materials must be conducted within BSCs or other physical containment devices. A BSL-3 laboratory has special engineering and design features.

BSL 4 - is required for work with dangerous and exotic agents that pose a high risk of aerosol-transmitted laboratory infections and life-threatening disease. BSL-4 laboratories are not allowed at Stony Brook University.

ABSL 1 - is suitable for animal work involving well-characterized agents not known to consistently cause disease in immunocompetent adult humans and present minimal potential hazard to laboratory personnel and the environment. Work is typically conducted on open bench tops using standard microbiological practices. Special containment or facility design is not required, but may be used as determined by appropriate risk assessment. Laboratory personnel receive specific training in the procedures conducted in the laboratory and are supervised by a scientist with training in microbiology or a related science.

ABSL-2 - builds upon the practices, procedures, containment equipment, and facility requirements of ABSL-1. ABSL-2 is suitable for work involving laboratory animals infected with agents associated with human disease and pose moderate potential hazards to personnel and the environment. It also address hazards from ingestionand from percutaneous and mucus membrane exposure. ABSL-2 requires that, in addition to the requirements for ABSL-1, a BSC or other physical containment equipment is used when procedures involve the manipulation of infectious materials or where aerosols or splashes may be created. Appropriate PPE is worn to reduce exposure to the infectious agents, animals, and contaminated equipment.  An appropriate occupational health program is in place, as determined by risk assessment.

ABSL-3 - involves practices suitable for work with laboratory animals infected with indigenous or exotic agents which may cause serious or potentially lethal disease as a result of exposure by inhalation. ABSL-3 builds upon the standard practices, procedures, containment equipment, and facility requirements of ABSL-2. The ABSL-3 facility has special engineering and design features. ABSL-3 requires that in addition to the requirements for ABSL-2, all procedures are conducted in BSCs or by use of other physical containment equipment. Inward airflow at the containment boundary is maintained.  Handwashing sinks are capable of hands-free operation. Appropriate PPE is worn to reduce exposure to infectious agents, animals, and contaminated equipment.

ABSL-4 - is required for work with animals infected with dangerous and exotic agents that pose a high individual risk of aerosol-transmitted laboratory infections and life-threatening diseases that are frequently fatal agents for which there are no vaccines or treatments. ABSL-4 laboratories are not allowed at Stony Brook University.

For details on the criteria, practices, and facility requirements for each biosafety level go to:

Biosafety Levels - Biosafety in Microbiological and Biomedical Laboratories (BMBL) 6th Edition