The Center for Disease Control (CDC) in conjunction with the National Institutes of Health (NIH) has defined four biosafety levels, BSL-1 through BSL-4 (see: Biosafety in Microbiological and Biomedical Laboratories in reference materials). Within each level, laboratory practices and techniques, laboratory facilities and engineering controls have been recommended for the handling of hazards imposed by the infectious organisms within each biosafety level. The following is a summary of recommended biosafety levels for infectious agents.
| BSL | Agents | Practices | Safety Equipment | Laboratory Facilities |
|---|---|---|---|---|
| 1 | Not known to consistently cause disease in healthy adults. Examples: Bacillus subtilis, Naegleria gruberi, canine hepatitis. | Standard Microbiological Practices. | None required. | Open bench top. |
| 2 | Associated with human disease. Hazards are percutaneous injury, ingestion, muccous membrane exposure. Examples: HIV, hepatitus B, salmonellae, toxoplasma. | BSL-1 practice plus:
|
Primary barriers are Class I or Class II BSCs, or other physical containment devices used for all manipulations of agents that cause splashes or aerosols of infectious materials. PPEs include lab coats, gloves, face protection as needed. | BSL-1, plus:
|
| 3 | Indigenous or exotic agents with the potential for aerosol transmission. Disease may have serious or lethal consequences. Examples: St Louis encephalitis virus, Coxiella burnetii, Mycobacterium tuberculosis. | BSL-2 practice plus:
|
Primary barriers are Class I or Class II BSCs or other physical containment devices, used for all open manipulations of agents. PPEs include protective lab clothing, gloves, and respiratory protection as needed. | BSL-2 plus:
|
| 4 | Dangerous/exotic agents which pose high risk of life-threatening disease, aerosol-tranmitted lab infections or related agents with unknown risk of transmission. Examples: Lassa fever virus, Marburg or Congo-Crimean hemorrhagic fever. | BSL-3 practice plus:
|
Primary barriers: All procedures are conducted in Class III BSCs OR use a full-body, air-supplied, positive pressure personnel suit, in combination with Class I or Class II BSCs. | BSL-3 plus:
|
You will notice that all classes of biological safety cabinets may be used as engineering controls for all biosafety levels, including BSL-4 with the proper personnel protection equipment (PPE). This includes chemical fume hoods and other custom physical containment devices, as long as they are properly validated to perform according to the requirements.
Types of Biological safety cabinets have been generally divided into three classes depending on the following factors; personnel, environmental, and product protections provided. Brief definitions are below:
| Class | Description | ||||||||
|---|---|---|---|---|---|---|---|---|---|
Class I * |
A ventilated cabinet that provides personnel and environmental protection. It is characterized by an unrecirculated inward flow of air away from the operator through a limited fixed access opening. Exhaust air must be HEPA filtered if recirculated back into the laboratory. May or may not be vented via a remote ventilation system. |
||||||||
Class II ** |
A ventilated cabinet that provides personnel, product and environmental protection. It is characterized by a limited fixed inward Air Flow access opening that provides personnel protection, a vertical downward HEPA filtered work zone that provides product protection and HEPA filtered exhaust providing environmental protection. They are divided into Types depending on the percentage of air volume exhausted:
|
||||||||
Class III * |
Provides absolute personnel protection, environmental protection and may provide product protection. It is characterized by a totally enclosed, gas-tight, negative pressure, HEPA filtered, ventilated workspace accessed through attached rubber gloves and purged interchange chambers. Exhaust air is treated by double HEPA filtration and/or incineration. |
||||||||
| * There are no nationally recognized specifications/standards governing construction and performance for these configurations (Class I, Class III). ** Construction and performance specifications for Class II cabinets are defined in the National Sanitation Foundations (NSF) Standard No. 49. |
The following table summarizes NuAire's biological safety cabinets versus Class
| Class | Model Number | Exhaust VS. Recirculated Air | Size (Nominal) | Protection Provided | Performance Specifications |
|---|---|---|---|---|---|
| 1 | 813 | 100% vs. 0% | 30" & 42" | Personnel | ASHRAE 110-1995 NSF personnel test |
| 819 | 100% vs. 0% | 30" & 42" | Personnel | ASHRAE 110-1995 NSF personnel test |
|
| 2 | 425 | 30% vs. 70% | 2, 3, 4, 6 ft. | Personnel, Environmental, and Product Protection | Fed. Std. No. 209e Class 10 |
| 427 | 70% vs. 30% | 4, 6 ft. | Personnel, Environmental, and Product Protection | NCI Class II, Type 2 7/06/1976 |
|
| 430 | 100% vs. 0% | 4, 6 ft. | Personnel, Environmental, and Product Protection | UL, UL-C Listed | |
| 440 | 30% vs. 70% | 3, 4, 6 ft. | Personnel, Environmental, and Product Protection | All The Above + GN 12469 |
|
| 480 | 30% vs. 70% | 3, 4, 5, 6 ft. | Personnel, Environmental, and Product Protection | All The Above + GN 12469 |
|
| 3 | 700 | 100% vs. 0% | 3, 4, 6 ft. | Absolute Personnel, Environmental, and Product Protection |
Halogen gas-tight Leak Test |
