The University of Arizona

Biosafety Cabinets

Research Laboratory & Safety Services

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Campus Mail:
PO Box 245101

Phone: (520) 626-6850
Fax: 520-626-2583

Mailing Address:
Research Laboratory & Safety Services
PO Box 245101
Tucson, AZ 85724

Street Address:
1717 E. Speedway Blvd, Suite 1201
Tucson, AZ 85719

How a BSC works

Biosafety cabinets are often referred to as "hoods" or "laminar flow hoods". It is important to know the difference between a biosafety cabinet, a chemical fume hood, and a clean bench.

  • Biosafety cabinets (BSC) are designed to protect the individual and the environment from biological agents, and to protect the research materials from contamination. Some laboratory procedures generate aerosols that may spread recombinant and biohazardous material in the work area and pose a risk of infection to the worker. Biological safety cabinets are used to prevent the escape of these aerosols or droplets.
  • Chemical fume hoods are designed solely to protect the individual from exposure to chemicals and noxious gases. They are not equipped with HEPA filters and therefore must not be used for work with biohazardous materials.
  • Horizontal laminar flow hoods or "clean benches" are not acceptable for work with biohazardous materials. The air is HEPA filtered and directed across the bench top toward the user. Thus, it offers no protection to the user, only the product.

Biosafety Cabinets

Class I Biosafety Cabinets are enclosures similar to chemical fume hoods, with an inward airflow through the front opening. The exhaust air from the biological safety cabinet is passed through a HEPA filter so that the equipment provides protection for the worker and the public. The product (research material) in the cabinet is, however, subject to contamination.

Class II Biosafety Cabinets are designed to protect the worker, the environment, and the product. Class II cabinets are vertical laminar-flow cabinets with a partially open front. Airborne contaminants in the cabinet are prevented from escaping across this opening by a curtain of air formed by unfiltered air flowing from the room into the cabinet and HEPA filtered air supplied from an overhead grill down into the cabinet. A portion of the filtered air is used to maintain the air curtain, and the remainder passes down onto the work surface, and is drawn out through the grills at the back and front edges of the work surface.

The HEPA filtered air from the overhead grill flows in a uniform downward movement to minimize the air turbulence. It is this air that provides and maintains a clear air work environment. A percentage of air drawn through the front and back grills of the work surface is also HEPA filtered and exhausted from the cabinet.  

Class III Biosafety Cabinets or glove boxes are gas tight cabinets and all operations within the cabinet are conducted through arm-length rubber gloves. Air entering class III cabinets is HEPA filtered and exhaust air is filtered through two HEPA filters in a series and exhausted directly to the outside.

Moving and Installation

Disinfect biosafety cabinet work surfaces prior to moving them to new facilities. Biosafety Cabinets used for work with pathogenic organisms may require paraformaldehyde decontamination before being moved. Contact Facilities Management at (520) 621-3000 for instructions.

Each biological safety cabinet must be recertified for correct air flow and filter integrity after it has been moved and placed in its final location. Contact Facilities Management at (520) 621-3000 for biosafety cabinet certification.

Decontamination and Maintenance

The Approval Holder is responsible for cleaning and decontaminating their biological safety cabinets. Facilities Management personnel will disconnect the cabinet and label when the cabinet was disconnected and decontaminated. If the safety cabinet is equipped with a UV light, do not use this as your primary disinfectant.

Certification Requirements

Biosafety cabinets should be registered with Research Laboratory & Safety Services and be certified annually. Annual certification ensures that the cabinet is working properly and that the HEPA filters are in good condition. Cabinet certification is scheduled through Facilities Management at (520) 621-3000. Make sure to inform Facilities Management of changes in your account number used to pay for your certification, since the codes are not updated automatically.

In additional to the annual certification, biosafety cabinets must also be certified:

  • After a cabinet has been moved even if shifted a short distance.
  • After maintenance procedure are performed on internal parts.
  • After HEPA filters have been changed.

The last inspection date should be easily visible.

Fume Hoods

Fume Hoods are ventilated enclosures that capture, contain, and remove chemical fumes and vapors from the laboratory. Air flows from the room into the hood workspace and out into the environment, through an exhaust system.

USED FOR: Controlling chemical fumes and vapors that are hazardous in high concentrations.

NOT BE USED FOR: Materials that are hazardous in low concentration and biohazardous materials. Fume hoods should not be used on applications where the material needs to be protected from outside air, as the fume hood does not have a built-in HEPA filter to protect and maintain the integrity of the sample.

Clean Benches

Clean Benches use a blower to force air through a HEPA filter over a work surface. After the air is filtered, it may be forced in either a horizontal or vertical direction, depending on the type of laminar flow.

USED FOR: Creating a "clean" workspace where samples/specimens are protected from contamination.

NOT USED FOR: Clean benches do not offer protection to the worker, so they should not be used in applications where toxic or biohazardous aerosols will be produced.