Recommended Procedures for the Proper Use of Biological Safety Cabinets

Read the operator's manual and follow all manufacturer's recommendations. Also, the NIH/CDC document, Primary Containment for Biohazards: Selection, Installation and Use of Biological Safety Cabinets, provides thorough information.
Locate the cabinet in an area where it will not be adversely affected by air currents:

a. Away from pedestrian traffic and doors.

b. Away from other room ventilation devices (i.e., supply diffusers, fans, fume hoods, etc.)

Movement of arms into and out of the cabinet can disrupt airflow and affect cabinet performance. When possible, place all materials needed for a procedure inside the cabinet prior to starting and avoid bringing unnecessary items into the cabinet. Having a written checklist of materials necessary for a specific activity can help prevent unnecessary movement after beginning a procedure. If it is necessary to move arms in and out of the cabinet, this should be done slowly and with movement perependicular to the face of the cabinet.
Before using, wipe work surface with 70% alcohol. Wipe off each item you need for your procedures and place in the cabinet.
Minimize air changes in the room by avoiding opening and closing of lab doors and pedestrian traffic. Make sure lab doors are closed prior to starting work in the biological safety cabinet.
Cabinets that are not vented to the outside may be turned off when not in use, however, be sure to allow the biological safety cabinet to run for at least 10 minutes before starting work.
Work at least 4" - 6" from the opening of the cabinet. Minimize the storage of materials in and around the biological safety cabinet. Many items in a hood can cause turbulence and disruption of the air flow.
Personal protective clothing such as gloves and a laboratory coat should be worn when working at the hood. The laboratory coats should be buttoned closed over the street clothes. A solid front, back closing gown will provide even better protection. Gloves should be pulled over the knitted wrists of the gown. Elasticized sleeves can also be worn to protect the investigator's wrists.
Stool height should be adjusted so that the investigator's face is above the front opening. Manipulation of materials should be delayed for one minute after putting arms in the hood to allow the hood environment to stabilize. Do not block front grill by resting arms on them or by putting notes or any other materials on them.
Carry out work on an absorbent pad to contain small spills. However, make sure this pad does not cover the front grill opening. Clean up spills as soon as they occur. Remove and disinfect the grill if contaminated. Allow cabinet to run for 10 minutes before resuming work. View Procedure for Spills.
Place contaminated materials toward the rear of the cabinet. Segregate contaminated and clean items. Work from "clean to dirty".
Disinfect the cabinet surfaces after use. Remove all materials and wipe all interior surfaces with 70% alcohol.
If there is a UV light incorporated within the cabinet, do not leave it on while working in the cabinet or when occupants are in the laboratory. However, the CDC (Centers for Disease Control) and the NIH (National Institutes of Health) agree the UV lamps are not recommended nor required in biological safety cabinets. (Review additional information on UV lamps in the Decontamination, Sterilization, Disinfection Section of the Biosafety Manual, under Radiation Methods).
Place a pan with disinfectant and/or a sharps container inside the biological safety cabinet for pipette discards. DO NOT use vertical pipette discard canisters on the floor outside of the cabinet.
It is not necessary to flame items. This creates turbulence in airflow and may compromise sterility, and heat build-up may damage the filters. The use of gas burners in biolocial safety cabinets is not recommended.
If you use a piece of equipment that creates air turbulence in the biological safety cabinet (such as a centrifuge, blender), place equipment in the back 1/3 of the cabinet, stop other work while equipment is operating.


Protect the building vacuum system from biohazards by placing an in-line HEPA cartridge filter between the vacuum trap system and the source valve in the cabinet.

HEPA Cartridge Filter

Never attempt to remove or change the biological safety cabinet's HEPA filters. Notify the Department of Environmental Health and Radiation Safety if cabinets are not functioning properly.
Leave the fan blower on in the cabinet for a short period of time (5 - 10 minutes) after finishing work to allow the system to purge.


BSC Class
Face Velocity
Airflow Pattern
Nonvolatile Toxic Chemicals and Radionuclides
Volatile Toxic Chemicals and Radionuclides
In at front through HEPA to the outside or into the room through HEPA
When exhausted outdoors 1,2
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

(minute amounts)

30% recirculated, 70% exhausted. Exhaust cabinet air must pass through a dedicated duct to the outside through a HEPA filter
(minute amounts) 1,2
II, B2
No recirculation; total exhaust to the outside through a HEPA filter
(small amounts) 1,2
II, A2
Similar to II, AI, but has 100 fpm intake air velocity and plenums are under negative pressure to room; exhaust air can be ducted to the outside through a canopy unit
When exhausted outdoors
(minute amounts) 1,2
Supply air is HEPA filtered. Exhaust air passes through two HEPA filters in series and is exhausted to the outside via a hard connection
(small amounts) 1,2
Installation may require a special duct to the outside, an in-line charcoal filter, and a spark proof (explosion proof) motor and other electrical components in the cabinet. Discharge of a Class I or Class II, Type A2 cabinet into a room should not occur if volatile chemicals are used.
2. In no instance should the chemical concentration approach the lower explosion limits of the compounds.




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