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Biosafety Cabinets

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Biosafety cabinetsBSCs are only one part of an overall

biosafety program, which requires consistent use of good microbiological practices, use of primary containment equipment and proper containment facility design.

BSCs were developed as workstations to provide personnel, environmental and product protection during the manipulation of infectious microorganisms..

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BSCsVarious types of containment and

clean air devices incorporate the use of HEPA filters in the exhaust and/or supply air system to remove airborne particulate material.

Depending on the configuration of these filters and the direction of the airflow, varying degrees of personnel, environmental and product protection can be achieved.

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BSCsBiosafety levels:Level 1:work is done with defined and

characterized strains of viable microorganisms not known to consistently cause disease in healthy adult humans.

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Level 2:work is done with the broad spectrum of

indigenous moderate-risk agents that are present in the community and associated with human disease of varying severity.

Level 3: work is done with indigenous or exotic

agents with a potential for respiratory

transmission, and which may cause serious and potentially lethal infection.

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Level 4:work with dangerous and exotic

agents that pose a high individual risk of life-threatening disease, which may be transmitted via the aerosol route and for which there is no available vaccine or therapy.

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BSC principle

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Figure 2. The Class I BSC (A) front opening; (B) sash; (C) exhaust HEPA filter; (D) exhaust plenum. Note: The cabinet needs to be hard connected to the building exhaust system if

toxic vapors are to be used.

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Figure 3. The Class II, Type A1 BSC (A) front opening; (B) sash; (C) exhaust HEPA filter; (D) supply HEPA filter; (E) common plenum; (F) blower.

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Figure 5A. The Class II, Type B1 BSC (classic design) (A) front opening; (B) sash; (C) exhaust HEPA filter; (D) supply HEPA filter; (E) negative pressure dedicated exhaust plenum; (F) blower; (G) additional HEPA filter for supply air. Note: The cabinet exhaust needs to be hard connected to the building exhaust system.

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Figure 8. The Class III BSC (A) glove ports with O-ring for attaching arm-length gloves to cabinet; (B) sash; (C) exhaust HEPA filter; (D) supply HEPA filter; (E) double-ended autoclave or pass-through box. Note: A chemical dunk tank may be installed which would be located beneath the work surface of the BSC with access from above. The cabinet exhaust needs to be hard connected to an exhaust system where the fan

is generally separate from the exhaust fans of the facility ventilation system. The exhaust air must be double HEPA-filtered

or HEPA-filtered and incinerated.

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BSC Class III

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BSC class

Face velocity

Air flow Pattern applications

Nonvolatile Toxic Chemicals and Radionuclides

Volatile Toxic Chemicals and Radionuclides

I 75 In at front through HEPA to the outside or into the room through HEPA (Figure 2)

YES When exhausted outdoors1,2

II A1 75 70% recirculated to the cabinet work area through HEPA; 30% balance can be exhausted through HEPA back into the room or to outside through a canopy unit (Figure 3)

YES NO (MINUTE AMOUNT)

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BSC CLASS FACE VELOCITY

AIR FLOW PATTERN NON VOLATILE

VOLATILE

II,B1 100 30% recirculated, 70% exhausted. Exhaust cabinet air must pass through a dedicated duct to the outside through a HEPA filter (Figures 5A, 5B)

YES YES

I,B2 100 No recirculation; total exhaust to the outside through a HEPA filter (Figure 6)

YES YES

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II,A2 100 Similar to II, A1, but has 100 Ifm intake air velocity and plenums are under negative pressure to room; exhaust air can be ducted to the outside through a canopy unit (Figure 7)

YES When exhausted outdoors (FORMALLY “B3”) (minute amounts)

III N/A Supply air is HELP filtered. Exhaust air passes through two HEPA filters in series and is exhausted to the outside via a hard connection (Figure 8)

YES YES

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Figure 11. A typical layout for working “clean to dirty” within a Class II BSC. Clean cultures (left) can be inoculated (center); contaminated pipettes can be discarded in the shallow pan and other contaminated materials can be placed in the biohazard bag (right). This arrangement is reversed for left-handed persons.

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Thank you