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Biological Safety Cabinets: Usage Guidelines

Follow these guidelines for working safely in a biological safety cabinet (BSC).

Improper use of a biological safety cabinet can result in contaminated cultures and expose workers to infectious organisms.

When used correctly, a curtain of room air enters the grill at the front edge of the BSC work surface and acts as a protective barrier. The air mixes with the recirculating air stream and passes through a HEPA filter downward toward the work surface, creating a contamination-free zone.

These guidelines aim to preserve the delicate air barrier that protects both the research product and the researcher.

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Use the cabinet as intended

  • See Biological Safety Cabinets: Overview for a discussion of different types of biosafety cabinets, purpose, certification, and decontamination requirements.
  • Do not use the top of the cabinet for storage; this can damage the HEPA filter.
  • Keep only necessary equipment or supplies inside the BSC.

Take precautions before beginning work

Start up procedures

  • Turn off the ultraviolet sterilizer (if so equipped) as soon as you enter the room.
  • Turn on all blowers and cabinet illumination lights.
  • Allow 5 minutes of operation to purge the system; check the flow alarm system and visual alarm function (if so equipped).
  • Decontaminate readily accessible interior surfaces with a disinfectant appropriate for the agents or suspected agents present.

Standard operation procedures

  • Never have the ultraviolet light on when working at the cabinet. It can cause eye damage and skin burns.
  • Avoid disrupting airflow:
    • Minimize movement (especially rapid movements) into and out of the BSC, or in areas near the BSC.
    • Do not block the front grill or rear vents with your arms or other materials.
    • Work at least 4 inches from the inside edge of the front vent.
  • Bunsen burners, other continuous flame devices, or flammable gases are prohibited in biosafety cabinets.
    Safer sterilization methods exist, such as touch-plate microburners equipped with a pilot light, small electric "furnaces," or pre-sterilized loops.
  • Beware of fire hazards associated with vaporized ethanol and isopropanol disinfectants.

Special precautions for ultraviolet (UV) lamps

EH&S Biosafety division strongly discourages UV lamps in BSCs.

National Institutes of Health (NIH), Centers for Disease Control and Prevention (CDC), National Science Foundation/ANSI, and the American Biological Safety Association agree that ultraviolet (UV) lamps are not recommended or necessary for decontamination in BSC’s.

If a UV lamp is used in your BSC, follow the procedures below.


  • Post a warning sign on the front of the BSC indicating the presence of UV light hazards.
  • The sign must say CAUTION: Turn off UV light before working.

Be aware of the hazards. Exposure to UV light can cause:

  • Painful eye and skin burns
  • Damaging exposure levels exist well after the output of the lamp bulb has dropped below the biocidal level.
  • Deterioration of some tubing
    • This can be dangerous if you're using a touch-o-matic burner with natural gas tubing in a BSC.

Be aware of the limitations:

  • Never rely on UV irradiation alone to disinfect a contaminated work area. UV is:
    • Not effective on porous materials that are opaque to the light such as wood or foam
    • Ineffective if a microbe is protected by dust, dirt, or organic matter
    • Affected by the accumulation of dust and dirt on the bulb surface
    • Effective only in direct line of site
    • UV does not work in shadowed areas, penetrate into cracks or through the grill work of a BSC
      • The spill area under the work surface of a BSC is a favorite hide out for fungal spore and hardy bacteria.
      • The UV lamp bulb remains lit long after the germicidal effectiveness is gone.

Take precautions during work:

  • Turn off UV lamps while the lab is occupied. The stainless steel interior of the BSC can reflect potentially hazardous illumination out of the opening of the cabinet.
  • Never have the UV lamp on while an operator is working in the cabinet.

After work is complete:

  • Turn the fan off and close the sash, if possible, when the UV lamp is on.


  • Clean UV lamp bulbs frequently by turning off the UV lamp then wiping off the surface of the room temperature lamp bulb with 70% alcohol.
  • Before replacing bulbs, clear the BSC of equipment and material, and disinfect it with 10% bleach and then clean with 70% ethanol.
  • Install the bulb with gloved hands to prevent oil build up.
  • Disinfect lamp bulbs before disposal as universal waste.

Shut down procedures

When you are done:

  • Decontaminate and remove all items from the interior work area.
  • Decontaminate readily accessible interior surfaces with a disinfectant appropriate for the agents or suspected agents present.
  • Turn on ultraviolet sterilizer (if so equipped). Note: Never rely on UV irradiation of the work area alone to disinfect a contaminated work area.
  • Allow 5 minutes of operation to purge the system.
  • Turn off the blower.


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