Class II Biological Safety Cabinets and Enclosures

Biosafety cabinets (BSCs) are classified into three primary classes based on the level of protection they provide. Learn more about biosafety cabinet classes:

• Class I: Protects personnel and the environment by filtering air before it is exhausted. It does not protect products since unfiltered room air flows over the work surface. Learn how Class I cabinets work 
• Class II: Provides protection for personnel, the product, and the environment. Class II BSCs are subdivided into five types: Explore Class II cabinet types 
  • Type A1: Rarely used in the industry today due to safety and exhaust handling limitations.
  • Type A2: The most common BSC type. It recirculates approximately 70% of air through a HEPA filter and exhausts 30%. It can handle trace amounts of volatile chemicals if externally vented. Learn how Type A2 cabinets work 
  • Type B1: Recirculates 30% of air and exhausts 70%, suitable for work with low amounts of toxic chemicals and radionuclides. It offers a dedicated exhaust portion of the work surface for minimal volatile chemical use. Learn how Type B1 cabinets work
  • Type B2: 100% of the air is exhausted to the outside, making it ideal for use with hazardous chemicals or pathogens. Learn how Type B2 cabinets work 
  • Type C1: A hybrid cabinet that offers both recirculation and limited exhaust capabilities, depending on the application. Learn about Type C1 cabinets 
• Class III: A fully enclosed, gas-tight cabinet that provides the highest level of protection for personnel, product, and the environment. These are typically used for highly hazardous agents, such as in BSL-4 laboratories. Learn how Class III cabinets work 

Biosafety cabinets (BSCs) provide protection in three key areas:

• Personnel: Contain harmful agents to prevent exposure.
• Product: Maintain a sterile environment for sensitive materials.
• Environment: Contain contaminants to prevent environmental exposure.

Biosafety cabinets (BSCs) must be certified at least annually by a qualified technician, as required by NSF/ANSI 49 standards. Certification ensures proper airflow, filter integrity, and overall cabinet performance to maintain personnel, product, and environmental protection. During certification, technicians test airflow patterns, check filter integrity, and confirm that the cabinet meets performance specifications.

For facilities operating under USP <797> or USP <800> standards (e.g., sterile compounding pharmacies), certification is required biannually (every six months) to ensure compliance with strict air cleanliness and containment requirements. Learn more about field certification requirements.

Additional notes:

• Regular Maintenance: Routine cleaning, pre-filter inspections, and airflow monitoring are essential to extend the life of the equipment and maintain safety.
• HEPA Filter Checks: Depending on workload and environment, filters should be inspected during certification and replaced as necessary.

• Type A2: Handles trace amounts of chemicals if externally vented.
• Type B1: Offers a dedicated exhaust portion for minimal volatile chemical use and limited exhaust capabilities.
• Type B2: Fully exhausts all air, suitable for significant hazardous chemical use.
• Type C1: A hybrid cabinet for occasional exhaust of limited chemical vapors.

The CDC/NIH Biosafety in Microbiological and Biomedical Laboratories (BMBL) 6th Edition provides detailed guidelines on the use of biosafety cabinets with volatile chemicals. According to the BMBL:

• BSCs that recirculate air, such as Class II Type A1/A2, are generally not suitable for use with hazardous volatile chemicals or radionuclides unless externally vented.
• Class II Type B1 and B2 cabinets are more appropriate for chemical vapor containment. Type B1 provides partial exhaust, while Type B2 fully exhausts all air, making it ideal for hazardous chemicals.
• HEPA filters do not capture chemical vapors, which must be properly vented outside the lab to prevent accumulation.

HEPA filters typically last several years, but their lifespan depends on usage, load, and environmental factors. Regular airflow monitoring and annual certification help determine replacement needs. Learn more about HEPA filter lifespan. 

• Stop work immediately.
• Check controls: Review the system for diagnostics.
• Call for service: Contact a certified technician to resolve the issue.

For detailed guidance on responding to alarms, visit Reacting to Alarms in Class II, Type A2 Biosafety Cabinets. 

• Use a disinfectant: Choose a disinfectant appropriate for the contaminants being handled (e.g., bleach or ethanol).
• Clean work surfaces: Wipe down the work surface and clean beneath the tray if accessible.
• Maintain pre-filters: Regularly check and clean pre-filters or drainage systems to ensure proper airflow and drainage.

For more details, refer to Surface Decontamination in a Biosafety Cabinet or learn about Containing Spills in Class II, Type A2 Biosafety Cabinets.

Many biosafety cabinets (BSCs) feature adjustable bases, sloped front windows, and spacious work zones to reduce strain during use. Some models also include height adjustability, allowing for comfortable operation in both seated and standing positions. Learn more about ergonomic features in biosafety cabinets. 

Modern biosafety cabinets (BSCs) are designed to operate at low noise levels, typically under 60 dBA, which is quieter than a normal conversation. This low noise level ensures a comfortable work environment and reduces distractions for laboratory personnel during prolonged tasks.

The NSF/ANSI 49 standard specifies that the overall noise level in front of the cabinet should not exceed 67 dBA when the ambient noise level in the room is 57 dBA or lower. Measurements are taken 12 inches in front of the cabinet’s leading edge and 15 inches above the work surface, simulating the position of the user’s head. For comparison, the EN12469 standard measures noise at a point 1 meter from the cabinet and centered on the aperture, resulting in slightly lower reported dBA values. This distinction in testing methods is important when comparing noise data across standards.

Noise levels can also vary depending on ambient sound, room acoustics, and the presence of other equipment. Cabinets placed in smaller rooms may seem louder due to sound reflections, even if their noise levels are within certified limits. Advanced fan motor designs and the use of EC or DC motors in modern BSCs help minimize noise generated by airflow and mechanical vibrations.

For additional details, refer to the Noise Considerations in Laboratories Bulletin.

Basic maintenance tasks such as cleaning surfaces and replacing pre-filters (if present) can typically be performed by lab personnel. These routine actions help maintain cleanliness and ensure optimal airflow. However, more complex tasks, such as HEPA filter replacement and airflow adjustments, should always be handled by certified technicians to ensure safety and compliance with standards.

For guidance on basic maintenance, refer to Checking the Paper Catch in a Biosafety Cabinet. For broader operational best practices, explore Working Safely in Class II, Type A2 Biosafety Cabinets.

Proper shutdown of a biosafety cabinet (BSC) is essential for maintaining safety, cabinet performance, and regulatory compliance. Here’s a recommended protocol:

• Purge the air: Let the BSC operate for at least 5 minutes after completing work to purge airborne contaminants. This step is critical for minimizing the release of potentially harmful aerosols.
• Surface cleaning: Wipe down the work surface, sidewalls, and interior sash with an appropriate disinfectant. For guidance, visit our Surface Decontamination in a Biosafety Cabinet resource.
• Waste disposal: Safely remove all waste and materials, following your institution’s biosafety protocols. See our SOPs: Biosafety Cabinet Use Guide for detailed best practices.
• Check operating labels: Always refer to the cabinet’s posted operating instructions. Our Biosafety Cabinet Operating Label Infographic is a helpful quick reference.
• Power down: Turn off internal equipment, then switch off the blower and light (unless your cabinet is equipped with night setback mode, like NuAire’s Night Care™). To learn how to work safely and efficiently, check out our Working Safely in a Class II, Type A2 Biosafety Cabinet article.

For a quick visual guide, you can also watch When Work is Completed in the Biosafety Cabinet - Video.

Following these steps helps reduce contamination risks and extends your cabinet’s lifespan. Always consult your lab’s specific biosafety manual and NuAire’s operating instructions for model-specific recommendations.

Yes, biosafety cabinets (BSCs) can be relocated, but it's essential to follow strict safety and compliance procedures to protect personnel, samples, and your lab environment.

• Decontaminate: Before relocation, the BSC must undergo thorough decontamination. For units exposed to hazardous or infectious materials, gaseous or vaporized sterilants are recommended for deep disinfection. See our Biosafety Cabinet Movement & Re-Certification Bulletin and Gas Decontamination Considerations for full instructions.
• Certification: After moving, a certified technician must re-certify the cabinet to verify airflow, filter integrity, and overall safety performance. Learn more in our Field Certification of Biosafety Cabinets guide.
• Safe transport: Always move the BSC upright to protect sensitive components like HEPA filters and internal blowers. Use appropriate lifting gear and avoid tilting.
• Optimal placement: Install the cabinet in a location that minimizes airflow disruption—avoid areas near doors, HVAC vents, or high-traffic corridors. For detailed planning, visit our Biosafety Cabinet Installation & Design Considerations.

Relocating a BSC without proper decontamination and re-certification can breach biosafety regulations and pose significant risks. Always coordinate with accredited biosafety professionals to ensure safety and compliance at every step.