5.4.4 Working Safely in a Biological Safety Cabinet

​General

  • General precautions and guidelines used outside containment equipment apply to work performed in a BSC.
  • BSCs should not be used in place of a chemical fume hood. Toxic and volatile chemicals are prohibited from biological safety cabinets. These chemicals as well as biological toxins should be manipulated in a chemical fume hood. 
  • Plan ahead to ensure minimal disruptions including room traffic or entry/exit, and restocking of supplies or materials in the cabinet. 
  • Open flames may not be used.
  • Personnel should be trained by laboratory staff in proper BSC use.

Personal protection 

  • Wear protective gloves when handling biohazardous agents; preferably "double-glove."  Change gloves if they become contaminated. A “double-glove” technique is advisable when working in a BSC, allowing users to change contaminated gloves without interrupting cabinet airflow. 
  • Personal protective equipment is still necessary when using a BSC. Gloves and a lab coat are the minimal PPE required when working in a BSC. 

Material Placement

  • The front intake grill of the Class II BSC must not be blocked with paper, equipment or other items.
  • All materials, including aerosol-generating equipment, should be placed towards the rear of the cabinet without blocking the rear grill.
  • Active work should flow from clean to contaminated areas across the work surface.
  • An autoclavable biohazard bag and pipette collection tray should be placed inside the cabinet as frequent in and out movements when using these containers disrupts the integrity of the cabinet’s air barrier and can compromise both personnel and product protection.

Work practices 

  • Move arms and hands slowly in the cabinet, wait one minute for air currents to settle, then begin work. 
  • Don't place anything on the grillwork inside the cabinet.  This greatly interferes with the airflow. 
  • Decontaminate work surfaces with an appropriate disinfectant before and after work, and after a spill. 
  • Perform all procedures carefully to avoid the generation of aerosols, splashes and spills. 
  • Keep an appropriate disinfectant agent within the cabinet. 
  • Keep the number of items in a BSC to an absolute minimum. 

Decontamination and Spills

- see Section 8

Ultraviolet (UV) Lights 

  • ABSA (American Biological Safety Association), CDC, NIH and NSF (National Sanitation Foundation) agree that UV lights are not recommended in BSCs.
  • Several factors influence the effectiveness of UV lights, including:
    • Humidity – above 70 percent germicidal activity is drastically reduced.
    • Dynamic air flow within the cabinet – reduces the penetration of the light and also cools the lamps, resulting in reduced output.
    • Age – effective UV radiation emitted from the lamps decreases with age.
  • If used:
    • The light must only be used when the biological safety cabinet sash is fully closed. Sash alarms or mechanisms ensuring this feature may not be disabled.
    • All items to be removed from the BSC and surfaces of the BSC must be decontaminated prior to UV light use.
    • They must be cleaned weekly (alcohol/water mixture) in order to remove dust and dirt that can block the germicidal effectiveness of the light.
    • Ultraviolet light intensity should be checked or replaced annually to ensure the emitted intensity is sufficient for germicidal activity.
  • UV lights must be turned off whenever the room is occupied.
  • If UV lights will be used overnight or for extended periods of time while staff are not present, signage should be posted on the closed door of the room. 

Cabinets 

  • Cabinet selection should be determined by assessing personnel protection against Risk Group 1-4 agents, personnel protection against radionuclides and volatile toxic chemicals, product protection, and the environment; or a combination of these. 
  • HEPA filters do not provide protection against gases and vapors.  They do provide protection against particulate agents and materials. 
  • BSCs should be certified after installation, but before being used, whenever moved, and at least annually thereafter.