Biological Safety Cabinets

Biological Safety Cabinets (BSC) are primary barrier protection for individuals working with biological materials.  This primary containment device is designed to remove aerosols at the site of their generation and therefore limit spread by contact with the user. A BSC not only provides protection of the user, but it also protects the environment and provides a clean work environment which protects the product. 

Click on a topic below to expand with more information.

How does the BSC work? 

Personnel Protection:

BSCs use vertical laminar airflow to create a barrier at the front of the cabinet. This air curtain protects the user from the biohazardous aerosols that may be created during procedures inside the cabinet. This air curtain can be interrupted by opening nearby doors, quick movements in and out of the cabinet, or movement from side to side. Formation of the protective air curtain is also disrupted when the front air intake grille is blocked. Even a sheet of paper placed on the front intake grille could result in a loss of containment.

The proper location of the cabinet within the laboratory and safe work practices are important in the proper function of the cabinet. It is important that all users understand the importance of the air curtain as it is the barrier between the user and the potentially infectious aerosols within the cabinet.

Product and Environment Protection:

Room air is drawn down into the front grill of the cabinet without entering the cabinet. This room air along with air being drawn out from within the cabinet are cleaned with High-Efficiency Particulate Air (HEPA) filters before being supplied to the work area in the cabinet or released to the environment.

When should I use a BSC? 

BSCs should be used for all procedures with potentially infectious or infectious materials that are likely to create aerosols. Aerosols can be created by any activity where energy is exerted including opening caps, pipetting, vortexing, aspirating, sonicating, etc. Therefore, a BSC is recommended for all manipulations of infectious materials.

What if what I’m working with is only a contact hazard?

While aerosols are suspended in air, they are an inhalation hazard. However, as aerosols settle they become a contact hazard. BSCs remove aerosols at the site of generation limiting the spread by contact with the user. Therefore, a BSC is still recommended for manipulations of infectious agents that are only spread by direct contact.

Work Practices for Use of a BSC 

  • Do not allow others to walk rapidly behind you when you are working.
  • Be aware of drafts from ventilation systems, doors, windows, fans, etc.
  • Plan procedures carefully. 
  • Start-up biosafety cabinet and decontaminate with Wescodyne or suitable disinfectant.
  • Let biosafety cabinet run at least 5 minutes to purge air in the work area.
  • Do not place items over front grille, do not block back grille.
  • Separate clean and contaminated items.
  • Use plastic backed towels on the work surface to absorb spills.
  • Minimize storage items in or near the biosafety cabinet.
  • Wash hands and arms before and after work.
  • Wear a rear tie gown with gathered/knitted cuffs.
  • Wear long sleeve nitrile or latex gloves.
  • Minimize movement of contaminated items over clean items (work from clean to dirty).
  • Perform work 6 inches back of front intake grille.
  • Hold tubes, bottles, and other vessels as horizontal as possible.
  • Use horizontal pipette discard pan with a disinfectant such as Wescodyne.
  • Do not use vertical pipette canisters or use them outside of a biosafety cabinet.
  • Ultraviolet lights are not needed if good technique is followed.
  • Do not overload the cabinet. Nothing should pass out of cabinet until work is complete.
  • Place clean items toward the front, contaminated toward the rear.
  • Remove contaminated items only after sealed or decontaminated.
  • Do not use a flame.  Turbulence and filter damage may occur.
  • Use disposable loops, swabs, needles, syringes, etc. whenever possible.
  • Do not use a biosafety cabinet for storage.
  • Equipment that causes turbulence (centrifuge, blender, etc.) should be placed in back 1/3 of the work surface. All other work in the cabinet should stop while the apparatus is running.
  • Decontaminate after work is complete with Wescodyne or other appropriate disinfectants.

CDC/NIH Biosafety Cabinet Training Course

BSC vs Fume Hood 

BSCs are not fume hoods and should not be used for work with volatile chemicals or radioactive materials. If your biohazardous work requires the use of chemicals or radioactive materials, you must use a class II type B2 BSC that is also UL classified as a fume hood. Very few laboratories on the University campus have this type cabinet.

BSC vs Clean Air Bench 

Clean Air Benches are not biological safety cabinets.  Clean Air Benches provide only product protection through a unidirectional airflow toward the operator.  These benches may not be used when handling cell culture materials or drug formulations, or when manipulating potentially infectious materials. These devices should not be used in research, biomedical or veterinary laboratories at the University. 

Open Flames in a BSC 

Open flames are not permitted in BSCs at the University of Maryland, Baltimore. The use of open flames, such as Bunsen burners, in a BSC disrupts the air flow in the cabinet which in turn compromises the protection of both the worker and the product. In addition,  open flames can cause damage to the HEPA filter because the heat may melt the adhesive holding the HEPA filter together or if the flame is too large or ignites an ethanol wash bottle it could burn a hole in the filter.  An alternative to using an open flame is a sterilizing device called a Bacti-Cinerator.  This device sterilizes using infrared heat and eliminates the need for an open flame or hazardous gas inside of the BSC.

For more information, please visit: Bacti-Cinerator

UV Light for Decontamination 

The Centers for Disease Control (CDC) and the National Institute of Health (NIH) agree that UV lamps are not recommended nor required in biological safety cabinets.  Overexposure to UV light is not only detrimental to humans but its use as a sterilization or decontamination tool is also limited by a number of factors.  These include: penetrating power, relative humidity, temperature, cleanliness, and age.  The American Biological Safety Association (ABSA International) has published a paper which sets forth their position regarding the use of UV Lights in BSC’s.

View ABSA’s paper on UV Lights

Certification of BSCs 

Biosafety cabinets are primary barrier protection for individuals working with biological materials. This equipment must be properly maintained by having them professionally certified every year.

  • All biosafety cabinets must be certified annually.
  • New biosafety cabinets must be validated by certification before they are put into service.
  • All biosafety cabinets must be certified after they have been repaired or relocated. 
  • Annual biosafety cabinet certification is required according to: 

    • The CDC/NIH Biosafety in Microbiological and Biomedical Laboratories (BMBL)
      6th Edition, June 2020
    • World Health Organization (WHO) Laboratory Biosafety Manual
      4th Edition, 2020
    • The NIH Guidelines for Research Involving Recombinant or Synthetic Nucleic Acid Molecules, April 2019
    • The NSF/ANSI Standard 49-2020: Biosafety Cabinetry - Design, Construction, Performance and Field Certification
    • The Food and Drug Administration

Suggested Source for Certification and Repair Service

  • For vendor recommendations, please contact a member of the EHS Research Safety team at (410) 706-7055.

Purchasing or Moving a BSC 

Purchasing a new BSC:

New biosafety cabinets must be professionally certified before they are put into service (and then like all BSCs, certified again annually and after repair or relocation). The Biosafety Office must approve the location for the cabinet to ensure there are no obstacles to proper functioning.

Moving a BSC:

Before a BSC is relocated, disposed of, or moved in any way, it must be decontaminated by a vendor.  After decontamination, the vendor will place a certification sticker on the cabinet, indicating that the cabinet has been decontaminated.  The Biosafety Office must then approve the location for the cabinet to be relocated. Once relocated, a vendor must certify the cabinet in its new location before it is put into service.


For more information please contact a member of the EHS Biosafety Office at (410) 706-7055.