A2 Vs B2 Biosafety Cabinets: How to Choose One for Optimal Lab Safety?

Choosing an appropriate Class II biosafety cabinet or BSC is not just pinning on any model.  It is also about matching the ventilation of the facility, the airflow design, and the hazards you handle. The commonest sub types of BSCs are Class II, Types A2 and Class II Types B2.

Here is a practical guide to what each does, the trade-offs, and how to decide which one helps maintain optimal safety in the laboratory.

Differences between A2 and B2 Biosafety Cabinets

When it comes to biosafety cabinet Class II A2 also called recirculating cabinets, they draw room air through the front and make it free from contaminants through HEPA filters. Thereafter, a major portion of downflow air returns to the work area while exhausting a percentage to the building exhaust. The major function of the equipment to protect the user and product for routine microbiological work but cannot handle volatile toxic chemicals unless it is properly exhausted.

For Class B2 and type II biosafety or total exhaust cabinets, they are 100% externally exhausted and there is no recirculation. All air entering the cabinet is HEPA-filtered and then sent outside directly through ducts. B2 models are needed where biological experiments send out hazardous vapors that are not meant to be recirculated.

Pros and Cons of Type II A2 and B2 Biosafety Cabinets

Take a look at the pros and cons of both types of BSCs at a glance:

Pros – Type II A2 BSC

• Biosafety cabinet class 2 type A2 is widely available, flexible, and less complex to install than B2
• Ideal for BSL-2 workflows like culture work and routine molecular biology where no volatile agents of hazardous chemicals are used

Cons – Type II A2 BSC

• Due to its partial recirculation feature, the equipment is not right for any work that produces chemical vapors, toxic gases, or radionuclide aerosols that may contaminate the HVAC within the room.

Pros – Type II B2 BSC

• It is devoid of recirculation risks and certainly safer for work involving chemical biology, volatile disinfectants, or when regulations require dedicated exhaustion
• It is ideal for laboratories handling toxicants or low-level radiological materials

Cons – Type II B2 BSC

• It requires critical ductwork, certified exhaust, and robust HVAC.
• Installation, commissioning, and operating costs are higher
• Requires advanced planning for seasonal impacts and backdraft control

How to Choose The Right Equipment?

Here are the steps to follow to make the right containment decision for your laboratory:

1. Run a Hazard and Risk Assessment of Procedures

You need to identify volumes, agents, and manipulations that create aerosols and whether you are planning to use fixatives, radionuclides, and volatile chemicals. Assessing risks is the cornerstone of most containment decisions.

2. Presence of Toxicants and Fumes

If the laboratory will have toxicants and fumes, you can choose Class II Types 2 BSC as A2 recirculation is unsafe for such use cases.

3. Evaluate the HVAC of your facility

B2 cabinets require dedicated exhaust, so you need to learn about capacity of HVAC. If it fails to meet the requirements, you need to switch to Biosafety Cabinet Class II A2 for optimal safety.

4. Standards and Certifications

When purchasing the biosafety cabinet, make sure to check if it is NSF certified. Besides, institutional policies may also specify which type of biosafety levels and procedures are permissible.

5. Budgeting

When it comes to budgeting, you must consider the cost of installing the device, maintenance, and energy needed for constant exhaust. The biosafety cabinet class 2 type A2 is cheaper upfront as well as cheaper to run. Although B2 costs are higher, it is needed for safety and regulatory compliance.

Practical Considerations and Red Flags

Check these practical considerations and red flags when buying a biosafety cabinet:

• Shared Space

If your laboratory has shared HVAC zones and incurs persistent use of chemicals, B2 cabinets are more appropriate although you need to confirm about makeup air.

• Noise and Room Climate

B2 cabinets can change room temperature and increase noise, so you need to plan the comfort and HVAC controls

• Training and SOPs

Choosing the devices comprises only half the work. You need to implement training, SOPs, and waste handling specific to the type of cabinet.

Final Thoughts

If your work is purely microbiological with no volatile toxicants, an A2 cabinet is usually the practical and economical choice. If your lab handles hazardous vapors, chemicals or radionuclides choose a B2 and plan for the HVAC, ductwork and operating costs that come with it.

Choose precision, reliability and compliance with IGene Labserve’s NSF certified biosafety cabinets. Our Class II A2 and B2 models meet the stringent NSF International, offering optimal protection for operator, environment and product. Visit to explore our lab products.