Biological Safety Cabinets*

There are three classes of BSCs: Class I, II, and III. While all three classes afford personnel and environmental protection, only Class II and III cabinets provide product protection.

Class I BSCs are suitable for work involving low to moderate-risk agents. Since incoming air is not filtered, Class I BSCs should not be used with research materials (e.g., cell lines) that must be handled under sterile conditions. Class I cabinets are used specifically to enclose equipment (e.g., centrifuges, harvesting equipment, or small fermenters) or procedures with potential to generate aerosols (e.g., cage dumping, tissue homogenization, or culture aeration). As outgoing air is filtered, research personnel are protected while using a Class I BSC.

Class II BSCs provide an effective partial barrier system for the safe manipulation of low, moderate, and high-risk microorganisms. Class II cabinets, which are the most frequently used in research and clinical laboratories, are divided into four types (Types A1, A2, B1 and B2).

The Class III BSC is a totally enclosed, gas-tight ventilated cabinet, and provides the highest level of personnel, environmental and product protection. Operations within a Class III BSC are conducted through attached rubber gloves.

TYPE A cabinet
Class II A2 biological safety cabinet

When purchasing a biological safety cabinet, you should consider the type of work that will be conducted in it. Table 1 provides a brief description of the principal characteristics of all classes and types of BSCs.

BSC CLASS / TYPE

PRODUCT PROTECTION

MINIMUM FACE VELOCITY FPM

VOLATILE TOXIC CHEMICALS, GASES OR RADIONUCLIDES ALLOWED?

I

No

75

No

II / A1

Yes

75

No

II / A2

Yes

100

No, unless thimble connected to the HVAC system, then low levels of volatile toxic chemicals allowed

II / B1

Yes

100

Yes: low levels of volatile toxic chemicals & trace radionuclides

II / B2

Yes

100

Yes: volatile toxic chemicals & radionuclides

III

Yes

N / A

Yes

Table 1: Characteristics of different classes and types of BSCs

Use of Ultraviolet (UV) Light in BSCs

EH&S does not prohibit UV light and it may be included when ordering a BSC. However, it is our opinion that is not necessary or recommended in biosafety cabinets. For more information, see article "Position Paper on the Use of Ultraviolet Lights in Biological Safety Cabinets" (Burgener, July, 2006, Applied Biosafety, 11(4) pp. 228-230).

Additional Sources of Information

  1. UW-Approved BSCs
  2. Baker: Introduction to BSCs
  3. Nuaire: How Class II BSCs Work


*This content is courtesy of the University of Vermont with permission, modified slightly to better fit the University of Washington BSC program.