| BSL-4, Biosafety Level 4Required for work with dangerous and exotic agents which pose a high individual risk of life-threatening disease. The facility is either in a separate building or in a controlled area within a building, which is completely isolated from all other areas of the building. Walls, floors, and ceilings of the facility are constructed to form a sealed internal shell which facilitates fumigation and is animal and insect proof. A dedicated non-recirculating ventilation system is provided. The supply and exhaust components of the system are balanced to assure directional airflow from the area of least hazard to the area(s) of greatest potential hazard. Within work areas of the facility, all activities are confined to Class III biological safety cabinets, or Class II biological safety cabinets used with one-piece positive pressure personnel suits ventilated by a life support system. The Biosafety Level 4 laboratory has special engineering and design features to prevent microorganisms from being disseminated into the environment. Personnel enter and leave the facility only through the clothing change and shower rooms, and shower each time they leave the facility. Personal clothing is removed in the outer clothing change room and kept there. A specially designed suit area may be provided in the facility to provide personnel protection equivalent to that provided by Class III cabinets. The exhaust air from the suit area is filtered by two sets of HEPA filters installed in series. Supplies and materials needed in the facility are brought in by way of double-doored autoclave, fumigation chamber, or airlock, which is appropriately decontaminated between each use. Viruses assigned to Biosafety Level 4 include Crimean-Congo hemorrhagic fever, Ebola, Junin, Lassa fever, Machupo, Marburg, and tick-borne encephalitis virus complex (including Absettarov, Hanzalova, Hypr, Kumlinge, Kyasanur Forest disease, Omsk hemorrhagic fever, and Russian Spring-Summer encephalitis). |
| BSL-3, Biosafety Level 3Applicable to clinical, diagnostic, teaching, and research or production facilities involving indigenous or exotic strains of agents which may cause serious or potentially lethal disease as a result of exposure by inhalation. All procedures involving the manipulation of infectious material are conducted within biological safety cabinets or other physical containment devices, or by personnel wearing appropriate personal protective clothing and equipment. The laboratory has special engineering and design features. A ducted exhaust air ventilation system is provided. This system creates directional airflow that draws air from “clean” areas toward “contaminated” areas. The High Efficiency Particulate Air (HEPA)-filtered exhaust air from Class II or Class III biological safety cabinets is discharged directly to outside or through the building exhaust system. The typical HEPA filter removes 99.97% of all particles that are 0.3 micron or larger in size, which means that all microbial agents will be trapped in the filter. Biosafety Level 3 practices, containment equipment, and facilities are recommended for manipulations of cultures or work involving production volumes or concentrations of cultures associated with most biological warfare agents. |
| BSL-2, Biosafety Level 2Suitable for work involving agents of moderate potential hazard to personnel and the environment. Agents which may produce disease of varying degrees of severity from exposure by injection, ingestion, absorption, and inhalation, but which are contained by good laboratory techniques are included in this level. Biosafety Level 2 practices, containment equipment, and facilities are recommended for activities using clinical materials and diagnostic quantities of infectious cultures associated with most biological warfare agents. |
| BSL-1, Biosafety Level 1Suitable for work involving well-characterized agents of no known or of minimal potential hazard to laboratory personnel and the environment. The laboratory is not necessarily separated from the general traffic patterns in the building. Work is generally conducted on open bench tops using standard microbiological practices. Special containment equipment is not required or generally used. This is the type of laboratory found in municipal water- ing laboratories, in high schools, and in some community colleges. |
