Biological Safety Cabinets

BSCs are workstations that provide personnel, environmental and product protection during the manipulation of infectious microorganisms. Certain considerations must be met to ensure maximum effectiveness of these primary barriers.



1.  BSCs must meet the specifications and be able to be certified to the current NSF/ANSI Standard 49.

2.  Biosafety cabinets must be certified by a qualified independent testing organization prior to building acceptance or for installations not involving significant building modifications, and before use with biohazardous materials.



3.  Clearance above the cabinet may be required to provide for accurate air velocity measurement across the exhaust filter surface and for exhaust filter changes.

4.  When the BSC is hard-ducted or connected by a canopy unit to the ventilation system, adequate space must be provided so that the configuration of the ductwork will not interfere with airflow.

5.  Adequate clearance should be provided behind and on each side of the cabinet to allow easy access for maintenance and to ensure that the cabinet air re-circulated to the laboratory is not hindered.



6.  The ideal location for the biological safety cabinet is as far from the entry to the laboratory as possible, i.e., the rear of the laboratory. BSCs should be located away from

  • Foot traffic
  • Open windows
  • Chemical fume hoods
  • Air supply registers
  • Portable fans
  • Laboratory equipment that creates air movement



7.  BSCs will be selected and approved by the Biosafety Officer. Change orders will not be accepted afterwards.

8.  Class II Type A2 BSCs are recommended for most work with biohazards contained at BSL-2. Class II A2 BSCs are preferable to Class II A1 because of the negative plenum design of the A2. At a minimum, Class II A1 or A2 BSCs must be used for biohazardous work. Class I BSCs will not be approved.

9.  The specific class, type and model BSC should be selected before the HVAC is designed for proper duct penetration placement. HVAC requirements and BSC characteristics are summarized in the table below. 


Additional Features

10. Exhaust airflow in the canopy/thimble connection must be 20-25% greater than the BSC manufacturer’s exhaust specifications. The canopy/thimble connection is provided by the BSC manufacturer.

11. Class II B2 BSCs must have fan interlocks so that when the exhaust fan is manually shut off, the internal blower shuts off.

12. Class III BSCs must be connected in a manner that prevents positive pressurization of the BSC.

13. Class II B2 and Class III BSCs must not be manifolded with other types of BSCs or fume hoods. Class II B2 BSCs can be manifolded with other Class II B2 BSCs.

14. Redundant exhaust fans should be provided for Class II B2 BSCs because primary containment depends on the building’s exhaust system.

15. Directly connected BSCs must have both audible and visual alarm systems to alert the user in the event of the loss of exhaust air flow.

16. BSCs must be seismically anchored.

17. UV lights are not required or recommended.

18. Natural gas is not recommended. If provided, the gas line shutoff valve must be easily accessible. The gas supply line must have flex gas lines and a pipe union between the shutoff valve and the wall.


Related Content/References

California Code of Regulations, Title 8, §5154.2. Ventilation Requirements for Biological Safety Cabinets

NSF/ANSI Standard 49 – 2014, Biosafety Cabinetry: Design, Construction, Performance, and Field Certification

CDC/NIH Biosafety in Microbiological and Biomedical Laboratories (BMBL) Appendix A – Primary Containment for Biohazards: Selection, Installation and Use of Biological Safety Cabinets