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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.

Hands-on training for proper use of a biosafety cabinet is available to researchers. Contact to schedule a class.

Use the cabinet as intended

  • See Biological Safety Cabinets: Overview for a discussion of different types of biosafety cabinets, purpose, placement, 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.
  • Larger equipment where biohazardous materials are used and/or stored, such as biosafety cabinets, incubators, refrigerators and freezers, must be visibly labeled with the universal biohazard symbol.

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.


Because UV lamp intensity (its destructive power) decreases with time, proper maintenance is critical for decontamination purposes. Perform this regular maintenance:

  • Clean UV lamp bulbs every other week by turning off the UV lamp then wiping off the surface of the room temperature lamp bulb with 70% alcohol, or in accordance with the manufacturer's instructions.
  • 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.
  • Check lamp efficiency monthly with a UV meter or monitoring strip.

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.


Contact EH&S Biosafety.