Class I biological safety cabinets protect the operator and the environment by drawing in air, filtering it, and then expelling it through HEPA filtration. These cabinets do not protect the handled material from external contamination because the airflow is non-sterile; they are suitable for procedures that require protection but do not require a sterile environment, such as certain operations involving microorganisms with low pathogenicity. 

Type II biological safety cabinets, the most commonly used in laboratories, provide triple protection: for the operator, the environment, and the product, including protection against cross-contamination. Thanks to a vertical laminar airflow filtered through HEPA or ULPA filters, they enable work under aseptic conditions with biological agents in risk groups 2 or 3, or during procedures requiring product protection (cell culture, clinical microbiology, biotechnology). This protection is particularly important for “low bioburden” testing; the European Pharmacopoeia states for microbial count tests: “Perform the count under conditions that prevent any extrinsic microbial contamination of the product under examination.”

Finally, Type III biosafety cabinets, which are fully enclosed and airtight, operate under negative pressure and provide the highest level of protection. Procedures are performed through built-in gloves, making them essential for working with highly pathogenic agents (risk groups 3 or 4) or for applications requiring strict biological containment.

This article describes the characteristics, use, and maintenance of Class II biological safety cabinets (BSCs), which are the most commonly used containment devices in pharmaceutical quality control laboratories.

The standards in the EN 12469 series (EN 12469-1 through EN 12469-5) form the cornerstone of European regulations governing the design, installation, performance, and use of biological safety cabinets (BSCs).

The information provided is intended to ensure the protection of operators, samples, and the environment, while ensuring the highest quality of laboratory processes.

1. Location

The scope of this standard extends beyond the intrinsic performance of the PSM: it directly influences the design and layout of laboratories. It highlights the sensitivity of PSMs to aerodynamic disturbances and therefore recommends that they be located away from sources of turbulence (doors, windows, air vents, high-traffic areas). Compliance with these recommendations is essential for maintaining optimal containment, in addition to meeting requirements regarding access to technical areas for maintenance and periodic inspections.

PSMs are sensitive to aerodynamic disturbances. Thus, localized air turbulence, temperature fluctuations, room layout, and large objects can affect the performance of the PSM

To ensure optimal containment, the following principles should be followed:

• At least 1.5 meters of space in front of the PSM
• At least 30 cm of clearance on the sides
• Clearances of at least 60 cm 
• Never place a PSM in front of or near a door, window, or air vent
• Leave 30 cm of space above for testing the HEPA filters
• Avoid installing two PSMs facing each other; if this cannot be avoided, leave a 3-meter gap between them.

2. Characteristics of Type II PSMs

At the heart of the standard are the airflow performance criteria, which are essential for ensuring containment integrity. Incoming air must maintain a minimum velocity of 0.4 m/s, ensuring a protective barrier at the front opening of the workstation, while the downward laminar flow must remain between 0.25 and 0.5 m/s to maintain the sterility of the work surface. 

The new versions of standards EN 12469-1, EN 12469-2, and EN 12469-5, published in November 2025, no longer specify reference values. Only the manufacturer’s specifications now apply, also due to the requirement for an operator protection test to be performed during commissioning and on a routine basis (potassium iodide method).

Suction-type PSMs draw in 30% of the ambient air, filter it, and recirculate 70% of that air as a laminar flow. Filtration relies on H14 HEPA filters with an efficiency of ≥ 99.995%, which are essential for capturing contaminated particles and aerosols. In addition to these parameters, the standard also includes important ergonomic requirements, such as a noise level of ≤ 65 dB(A) and a minimum illumination of 750 lux, ensuring a safe and comfortable working environment for the operator.

How it works:

• Guard vein: A peripheral airflow that prevents aerosols from escaping the work area. 
• Exhaust vents: Openings located around the countertop that allow for the extraction of downward airflow. 
• Plenum: An internal chamber through which air flows before being distributed and filtered. 
• Motorized ventilator: A device that draws in and blows out air through HEPA filters. 
• HEPA exhaust filter: A filter that traps particles before the air is expelled from the PSM. 
• HEPA supply air filter: A filter that delivers sterile air for the downward laminar flow.

Kaptitude Blog post titled “The Biological Safety Cabinet (BSC)” from June 23, 2020

3. Usage

Before introducing materials, the ventilation system must be running for at least 5 minutes if the PSM is in standby mode (low fan speed) and 15 minutes if it is completely turned off, in order to purge the work area and establish a stable laminar flow.

The operator must decontaminate surfaces using an appropriate product that meets the disinfection standards applicable to the activity. 

He must then organize the workspace by placing clean materials in a clearly designated area—for example, to the left of the work surface—and biological waste in a separate area—for example, to the right of the work surface—in order to ensure the product remains protected.

Any procedure that generates aerosols (including pipetting, homogenization, opening pressurized tubes, or handling infectious agents) must be performed inside the biosafety cabinet to ensure protection at all three levels: personnel, environment, and product.

When handling the equipment, avoid sudden movements, blockages of the intake grilles, and the introduction of bulky materials that could disrupt the flow rates.

Only essential items will be allowed inside the facility, and decontaminating them before bringing them into the cleanroom will help prevent contamination.

When handling samples, any residual nutrients (such as agar plates and broths) or microorganisms should be cleaned up immediately to prevent any risk of contamination

Once the procedures are complete, the shutdown procedure must be carried out in such a way as to ensure that the work area is decontaminated and that a stable airflow is restored before the device is shut down. The motorized fan must be left running for at least 10 minutes after operations have ended to allow for the complete purging of the work area and the removal of residual aerosols. During this phase, the operator methodically removes the used materials while adhering to the principle of unidirectional flow: contaminated materials are removed last to minimize any resuspension of biological agents. 

Once the flushing is complete, the work surface must be decontaminated with an appropriate disinfectant, as described in the following paragraph. 

After decontamination, the operator slowly removes their hands from the PSM, taking care not to abruptly disrupt the air curtain. The PSM may be shut down or left running, depending on the laboratory’s internal guidelines and operational needs.

Finally, thorough handwashing is essential to ensure the technician’s safety and prevent the spread of contaminants outside the laboratory. Wearing gloves and sleeve covers is also strongly recommended to enhance personal protection.

4. Cleaning

Regular decontamination of a Type  II biological safety cabinet (BSC) is an essential step in maintaining primary containment and preventing cross-contamination. There are two types of cleaning: routine cleaning, performed after each use, and periodic thorough cleaning, performed at regular intervals determined by each laboratory.

Thorough cleaning after each use.

At the end of each work session, a surface cleaning must be performed to remove microbial deposits and residues generated during the procedures.

Best practice guidelines recommend removing used consumables and materials, then thoroughly disinfecting all internal surfaces—including the work surface and side walls—with a suitable, non-corrosive disinfectant. After disinfection, a brief purging phase (typically 5 to 10  minutes) helps eliminate any residual aerosols. This systematic cleaning must be performed before and after each use to maintain the microbiological integrity of the laminar flow and ensure optimal protection of the product and personnel.

Thorough periodic cleaning.

In addition to routine cleaning, a thorough cleaning must be performed at intervals specified in each laboratory’s internal procedures, including, in particular, the disassembly of the work surface and exhaust grilles, followed by a thorough disinfection of the internal surfaces and the collection tray using an appropriate disinfectant

Thorough decontamination procedure.

In certain situations (before replacing HEPA filters or performing any internal work on the PSM, after a major spill, or when moving the PSM to another room), airborne decontamination using appropriate disinfectants (formaldehyde, vaporized hydrogen peroxide, etc.) may be required. This procedure allows access to internal components that cannot be reached by surface cleaning (plenum, supply air ducts, exhaust air ducts, fan motor

5. Maintenance and Inspection

Regular maintenance of PSMs is essential to ensure they function properly. 

Ultraviolet lamps are not required for PSMs; however, if they are used, it is essential to clean them weekly to remove any dust or dirt that could block their germicidal effect, and to check the intensity of the ultraviolet light during each PSM calibration to ensure that the light output is appropriate.

The effective lifespan of these lamps is limited. It will also be necessary to monitor them in order to schedule their replacement at the end of the recommended lifespan.

Ultraviolet lamps are not a substitute for regular decontamination of the PSM work surface and must be turned off whenever the room is occupied to protect the operator’s eyes and skin from harmful exposure.

In practice, the use of UV lamps under PSMs has not demonstrated any real additional effectiveness and cannot replace a rigorous cleaning and disinfection procedure for these devices.

Thorough and regular cleaning and disinfection of surfaces in the PSM is the most reliable and effective method for ensuring that biological risks are controlled.

The INRS states the following regarding UV rays:

Use of germicidal UV lamps. 

USE OF GERMICIDAL UV LAMPS

It should be noted that germicidal UV lamps are ineffective at treating the air circulating within the safety cabinet and that their UV output decreases very rapidly over time. However, they can be effective at decontaminating a work surface if it has been contaminated by microorganisms that are sensitive to UV light.

Of course, UV light should only be used when the PSM is shut down and locked, and no one is present.

If UV lamps are installed in the station, it is essential to:

• 1 – to ensure that their location does not impede the downward flow,
• 2 – to ensure their effectiveness against the microorganisms to be eliminated (lamp placement, power, and lifespan, as well as the required contact time). 

Preventive maintenance must be performed by qualified personnel and includes procedures designed to prevent failures that could compromise containment. These procedures include :

• checking that the motorized fan is working properly
• inspection of the electrical system, lighting, and acoustics, 
• Checking the mechanical condition of the internal components that are accessible after disassembly (plenum, grilles, drip pan)
• The PSM’s compliance must be verified at least once a year, as well as after any event that could affect its performance (relocation, major maintenance, HEPA filter replacement, or internal work). Regulations and institutional guidelines require that PSMs be certified to NSF/ANSI 49 or EN  12469 standards by an accredited body to ensure that inflow and downflow velocities, HEPA filter integrity, and the quality of the front air curtain meet regulatory criteria. 
• Finally, after any maintenance operation involving the opening of internal compartments or the replacement of filters, a full recertification of the PSM is required to ensure that it can be returned to service in a compliant and safe manner.

Conclusion.

Type II PSMs are essential tools for ensuring safety and quality in pharmaceutical laboratories. Proper use and regular maintenance are essential to maintaining their effectiveness and protecting operators, samples, and the environment.

References

• 1. INRS Guide ND2001-193-03: Microbiological Safety Cabinets. Cytotoxic Safety Cabinets – 2003
• 2. Biosafety Cabinet (BSC) Placement Requirements for New Buildings and Renovations NATIONAL INSTITUTES OF HEALTH Division of Technical Resources Office of Research Facilities – 1996–2023
• 3. Biological Safety Cabinet (BSC) Cleaning: Below the Deck NIH Division of Occupational Health and Safety – 2023
• 4. NF EN 12469-1 – 2025
• 5. NF EN 12469-2 – 2025
• 6. NF EN 12469-5 – 2025