Industrial Hygiene
Biological Safety Cabinets 

Biological Safety CabinetBiological safety cabinets (BSCs) are ventilated cabinets that use high efficiency particulate air (HEPA) filtration, laminar air flow, and containment to protect the operator, the product (pharmaceutical products as well as microorganisms), and the environment from aerosols generated from microbiological or pharmaceutical procedures performed within the laboratory or clean room.
They are the principle devices used to provide primary containment within the laboratory environment.

Cabinets are classified according to performance characteristics such as:

  • Air velocities and patterns
  • Exhaust system design
  • Cabinet construction
  • Protection of personnel, product, and the environment

These criteria dictate the type of work that can be performed within a BSC.
Thus, a cabinet designed for working with deadly microorganisms will be different than one used in a high school biology class.
For a detailed description of cabinet types see
 Biological Safety Cabinets: Types.

Prior to beginning a project that involves work within a BSC, a risk assessment should be conducted to determine which type of cabinet is appropriate for the type of work being performed.
When purchasing a BSC, it is essential to have the installation done by competent professionals, with the cabinet field certified prior to use.
For more information on certification, see  
Biological Safety Cabinets: Certification.

 Biological Safety Cabinet Airflow diagram. Image source: The Baker Company.

 Image source: The Baker Company

Industrial Hygiene Assistance

As part of a multidiscipline team, Army Industrial Hygiene, IAW AR 385-10, conducts lab surveys of new or recently renovated biosafety level 3 and 4 laboratories.
During the lab survey, the team uses an extensive checklist that includes employee medical surveillance, training, and adherence to numerous regulations and guidelines pertaining to laboratory work.
As part of the lab survey, team members check the proper location of
BSCs within the lab (away from high traffic areas, large equipment, doorways, and air diffusers).
They also verify National Sanitation Foundation accredited field certifiers
are used to test and certify all Class II BSCs.


1. What is the difference between cabinets and hoods and clean benches?

Biological safety cabinets are designed to provide protection of the operator, the product, or the environment from aerosols composed of liquid droplets and/or particulates including microorganisms.
They are not designed for work with volatile chemicals.
The HEPA filters that are an integral part of BSCs will not contain vapors and gases.
The use of HEPA filters allows for air to be re-circulated within the laboratory space.

Chemical fume hoods are designed to contain chemical vapors and gases generated while working with chemicals.
They are not designed for work with microorganisms.
Unlike BSCs, they will not provide protection of the product or the environment.
While BSCs air can be re-circulated, the chemical fume hood’s air is never re-circulated.
The term hood is often used to refer to BSCs.
As described above, a chemical fume hood is distinctly different from a BSC.
The terms should not be interchanged.

Clean benches look very much like BSCs but they are distinctly different.
Clean benches use HEPA filters to provide product protection only and are not suitable for work with either infectious microorganisms or volatile chemicals.

2. Can BSCs be used with chemicals?

BSCs are not designed for work with chemicals.
However, under certain conditions certain types of BSCs can be used with minute quantities of volatile toxic chemicals and tracer amounts of radionuclides required as an adjunct to microbiological studies.
The operator must know cabinet classification and type, the exhaust system being utilized, and how the work will be performed.
Due to the numerous variables involved, it is best to consult the manufacturer to determine whether or not working with chemicals or radionuclides is appropriate for a particular BSC.

3. How often should a BSC be tested/certified?

Generally, BSCs used in microbiology laboratories are certified at the time of installation, annually, when HEPA filters are changed, when maintenance or repairs are made to internal parts, or when the cabinet has been moved.
The National Sanitation Foundation recommends annual certification for Class II BSCs.
However, BSCs used in pharmaceutical applications are typically certified every 6 months.
 Biological Safety Cabinets: Certification.