International Biohazard SymbolBiological Safety

Using Biological Safety Cabinets

Biological safety cabinets (BSCs) are among the most effective primary containment devices used in laboratories working with infectious agents. They act as primary barriers to prevent the escape of biological aerosols into the laboratory environment. This is an important function, because most laboratory techniques (e.g., pipetting, vortexing, sonicating) are known to produce inadvertent aerosols that can be readily inhaled by the laboratory worker.

HEPA Filters

High Efficiency Particulate Air (HEPA) filters are present in all classes of BSCs. A HEPA filter removes only particulates (including microorganisms), not vapors or gasses, from the air. Depending on its quality, a HEPA filter is able to trap 99.97% of particles equal to and greater than 0.3 micron.

BSC Protection

BSCs are designed, in varying degrees, for:

A comprehensive description of BSC types, performance characteristics, and applications can be found in the publication Primary Containment for Biohazards: Selection, Installation and Use of Biological Safety Cabinets available online at:

Before selecting a cabinet, potential users must evaluate their program and match specific requirements with the appropriate equipment. The Biological Safety Section can assist researchers with these evaluations.

Policies for BSC Use

Certification Requirement

In order to ensure that BSCs are providing adequate personnel and environmental protection, it is required that BSCs are tested and certified on site:

PIs are responsible for ensuring that BSCs in their facilities are certified on an annual basis. For most departments, a Safety Contact has been established (typically a facility manager or safety coordinator) that will coordinate the certification of BSCs with a qualified vendor. If there is no established Safety Contact for the unit, the PI will be responsible for contacting a vendor themselves and scheduling the certification. Once annual certification is received, the Safety Contact (or PI if there is no designated Safety Contact) should update the campus BSC Inventory Database. Call or e-mail DRS for more information or see

Policy on use of uncertified biosafety cabinets

If a biosafety cabinet is not certified (either via certification expiration or certification failure) it must not be used as a primary safety device. From a safety perspective, an uncertified biosafety cabinet with the blowers running has the potential to disseminate potentially harmful material throughout the environment. Any work with pathogens or potentially infectious materials - even those considered Risk Group 1 - should not be performed in an uncertified cabinet.

Occasionally, there are requests to work with non-pathogenic material (e.g. plant or certain animal tissue cultures) in an uncertified cabinet. This should only be considered if the situation can be carefully managed. The cabinet should have a warning sign, and occupants of the laboratory should be trained on the limitations and potential hazards of using the equipment incorrectly. Such use is strongly discouraged in laboratories where pathogens or potentially infectious materials are also present since the potential for and risks of using the equipment incorrectly are increased.

If you have an uncertified biological safety cabinet and wish to use it for work with biological material, please contact the Biological Safety Section. We will work with you to develop a risk assessment to determine if the proposed use would qualify for an exemption from the certification requirement.

Chemicals in a BSC

BSCs should not be used in place of a chemical fume hood. Volatile or toxic chemicals should not be used in unducted Class II Type A cabinets since vapor build-up inside the cabinet presents a fire or explosion hazard. In addition, this type of cabinet recirculates air to the cabinet work space and exhausts into the room, potentially exposing the operator and other room occupants to toxic chemical vapors via the air flow. Biotoxins should also be manipulated in a chemical fume hood, see:

Gas connections, gas burners and alcohol lamps in the BSC

Gas connections to a BSC are not permitted without a DRS approved, written justification for specialized, limited duration work. Note that routine “flaming” is not considered adequate justification.

Open flames in BSCs:

Ultraviolet (UV) lamp usage

UV lamps are not required or recommended in BSCs. There is a potential for exposure to UV radiation above recommended limits if working in or near a BSC with a UV light in use. In addition, the germicidal activity of UV lights is limited by a number of factors, many of which are difficult to control. These include the ability of the light to penetrate the cabinet air flow, relative humidity levels >70%, ambient temperature <770 F and > 800 F, cleanliness of the bulb, and age of the bulb (should be measured every 6 months for intensity).

Use of Cabinet



Surface Decontamination – before work

Loading Materials and Equipment

Work Techniques

Final Purging

Unloading Materials and Equipment

Surface Decontamination – after work

Shutdown (Optional)


Contact the Division of Research Safety, Biological Safety Section (333-2755 or via e-mail) or visit our website:

Other Biosafety Facts Sheets are available from the Biological Safety Section at our website:

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