Biological Safety Cabinets

Biological safety cabinets or biosafety cabinets (BSCs) are used to protect personnel, products, and the environment from exposure to biohazards and prevent cross contamination of important samples.  BSCs are regularly used in a variety of laboratory types ranging from basic research to high containment.  Sometimes BSCs are referred to as tissue culture hoods, laminar flow cabinets, or just the hood.  Every BSC is categorized by a specific biosafety class which describes how the cabinet protects the user, the samples, and defines the types of work the cabinet is designed to handle. 

Biological Safety Cabinet Classes (and what they mean)

Biological Safety Cabinets are classified by how they protect the user and their research.  Each class of cabinet is designed to handle specific types of research and it is important to understand how the classes of cabinet work in order to select the right cabinet for your work.  When choosing a BSC for your workspace, EHS can help you select the class of cabinet that will provide the best protection. Please contact the Biological Safety Manager, Abbie Fish, at

There are three classes of BSCs that are all designed based on standards outlined by the Center's for Disease Control Guide: Biosafety in Microbiological and Biomedical Laboratories (BMBL) 6th Edition, and the National Science Foundation (NSF) Standard- Biosafety Cabinetry Certification: NSF/ANSI 49. All classes of cabinets are designed with inward negative airflow and rely on this air flow for protection. 

Class I BSC

A Class I BSC provides protection for the user and the environment ONLY.  This class of cabinets should not be used with research materials (e.g., cell lines) that must be handled under sterile conditions because incoming air is not filtered.  Class I cabinets are a great choice to enclose equipment (e.g., centrifuges) or for procedures with the potential to generate aerosols (e.g., dumping animal cages or tissue homogenization).  Air exhausted from the cabinet is HEPA-filtered therefore it is safe to exhaust the cabinet back into the lab. 

Class II BSC

A Class II BSC provides protection for the user, the samples or product, and the environment. Class II cabinets provide a partial barrier fort the safe manipulation of low, moderate, and high risk microorganisms and are often used for microbiological work and sterile pharmacy compounds. This class of BSC is sometimes referred to cell culture or tissue culture hood in the research setting and chemo hood in a pharmacy. Class II cabinets are most frequently used in research and clinical settings and can be further divided into four types: Types A1, A2, B1, and B2.  These four types are distinguished by differences in airflow patterns and velocities, HEPA filter positions, ventilation rates, and exhaust methods.  Additional details on the differences in Class II types can be found here


A Class III BSC is a totally enclosed, HEPA-ventilated and exhausted cabinet with leak-tight construction and attached rubber gloves for performing operations in the cabinet. These cabinets, sometimes referred to as a glove box, have a transfer chamber with interlocked doors that allow for sterilization of materials before entering/exiting the cabinet.  A Class III cabinet offers the highest level of protection for the user, the samples or products and the environment. These are generally used for work with high-risk or lethal microorganisms and are generally found in BSL3 and BSL4 laboratories.

Selecting a Biological Safety Cabinet

When purchasing a biological safety cabinet, it is important to consider the type of work that will take place in the cabinet. Please consult with EHS and your building coordinator prior to purchasing a new cabinet to ensure that you purchase the proper cabinet for your work and have the appropriate ventilation in place. 

BSC Class Personnel Protection Sample/Product Protection Environment Protection Minimum Face Velocity (MFV)

Cabinet Exhaust Type

Volatile, Toxic Chemicals, Gases, or Radionucleotides Allowed?

Class I Yes NO Yes >75  Recirculated in lab NO
Class II A1 Yes Yes Yes >75 Recirculated in lab


Class II A2 Yes Yes Yes >100 Recirculated in lab


**Hazardous chemicals can be used in this cabinet ONLY IF the cabinet is exhausted via canopy to the facility exhaust system.  

Class II B1 Yes Yes Yes >100 Exhausted from building Yes- Low levels of volatile, toxic chemicals permitted
Class II B2 Yes Yes Yes >100 Exhausted from building Yes- Low levels of volatile, toxic chemicals permitted
Class III Yes Yes Yes N/A Exhausted from building Yes- Low levels of volatile, toxic chemicals permitted


For more information on BSC Classes and assistance with selection, please contact EHS.

Additional Information

BSCs must be certified annually and after repairs, modifications, or relocation by a certified provider and it is the responsibility of the principal investigator to coordinate this certification. Certification ensures proper performance of the cabinet.  Cabinets that have not been certified within the past 12 calendar months, are not considered safe for use and work must cess until the cabinet has been certified. 

LSU works with two different companies for certification. Contact information is below. 

Company Phone Number(s) E-mail Website

(281) 474-3329

(281) 968-4126

(866) 464-5584

(281) 884-3909
ENV Services (800) 345-6094