Can ULPA filters filter bacteria and viruses?

This question needs to be answered in two levels, and it is easy to cause misunderstandings when talking about them together.

The first level: whether it can be captured. Microorganisms such as bacteria and fungal spores, usually in the micron range, can be intercepted by ULPA along with the air flow. The virus itself is smaller, but often attached to droplets, dust or other particles, and these carriers can be intercepted.

Second level: After the capture. This is the easily overlooked part. The filter traps microorganisms on the filter material, which does not mean killing or inactivating them. Microorganisms may still be living in the filter material. Therefore, the sentence 'ULPA can filter bacteria and viruses' refers to the capture ability, not the disinfection ability.

Distinguish between filtration and inactivation

The job of the filter is to separate particles from the air flow and trap them on the filter material.

Inactivation is another matter, which refers to making microorganisms inactive. This is a function of disinfection, sterilization or specific treatment means, not the function of the filter.

These two things are often conflated. Some people think that installing ULPA means the air is sterile. This is wrong. ULPA can reduce the concentration of microorganisms in the air, but it cannot guarantee absolute sterility downstream, nor can it replace necessary disinfection procedures.

Where biological contamination is involved, filtration is only one part of the entire control system and must be coordinated with other measures. The specific configuration must be determined according to the equipment purpose and project risk requirements, and cannot be judged solely by the filtering level.

Not a substitute for device verification

Biological safety cabinets, isolators, clean benches – these devices all have their own functional definition and validation requirements.

Replacing a clean workbench with ULPA cannot turn it into a biological safety cabinet. The airflow organization, exhaust method, and personnel protection design of the two are different. Upgrading the filtering level does not change the functional category of the device, nor does it replace corresponding system verification.

The selection or modification of equipment involving biological risks should be carried out in accordance with applicable specifications and risk assessments, and should not be judged solely on the basis of filter grade. In this type of project, the filter is just a component of the equipment, and its role must be understood within the entire system.

Control exposure during maintenance

If the filter traps particles containing microorganisms, the risk of exposure needs to be considered when replacing them.

Confirm isolation measures, personnel protection and packaging disposal procedures before replacement. The replaced filter element should be disposed of according to project requirements and should not be discarded or disassembled on site.

Do not use ordinary purging methods to clean potentially contaminated filter media. Purging will raise trapped particles back into the air, which can increase the risk of exposure. Whether special treatment is required and in what manner shall be carried out according to the procedures adopted by the project.

The exhaust filter structure cannot be changed at will. Exhaust systems involving biosafety usually have special requirements for filter location, sealing method and replacement process. Before adjustment, confirm whether they are within the allowable range. Device-side applications such as The EFU equipment-side fan filter unit has a compact internal space. The feasibility of maintenance operations needs to be confirmed at the planning stage to avoid discovering that the operating space is insufficient only after replacement.

Project judgment example

A laboratory replaced the filter of the clean workbench with ULPA, hoping to improve the level of protection.

This operation itself may be fine, but let’s be clear: after the replacement, the equipment is still not a biosafety cabinet. It cannot provide the personnel protection and exhaust treatment capabilities of a biological safety cabinet. If biosafety protection is required, equipment of the corresponding category should be selected instead of upgrading the filter element.

What this example illustrates is that filtering level and device functionality are two different dimensions and cannot replace each other. involving The selection of HEPA/ULPA air filters should be judged based on the overall functional positioning of the equipment.

What to look for during verification

The verification of biologically related occasions requires several more steps than general cleanliness projects.

Filtration integrity : Conduct on-site leak detection according to project requirements to confirm that there is no problem with the installation seal. For specific troubleshooting methods, please refer to the relevant instructions on confirming the installation direction of the equipment.

Airflow status : Confirm that the air supply volume, airflow direction and coverage meet the design requirements. The flow direction of biosafety-related equipment has clear requirements and cannot be adjusted at will.

Function verification : The safety functions, exhaust treatment, alarm system, etc. of the equipment itself must be confirmed separately according to the verification requirements of the equipment. This part has nothing to do with filters, but belongs to the scope of system verification.

Record retention : The filter number, installation location, leak detection results and replacement date should be kept accordingly. Where biological risks are involved, replacement records should also include protective measures and waste disposal conditions.

Selection and Acceptance Checklist

About Aili Industrial’s filtration packages

Filter selection for biologically related occasions requires clear equipment functions and verification requirements. Only when this part of the information is clear can we know what conditions the filter needs to meet.

Aili Industrial's manufacturing system covers filters, motors, fans, control systems and complete machine assembly, and can provide ULPA ultra-high efficiency filter and supporting air supply equipment. Filter can be used with FFU fan filter unit , EFU and other equipment are matched, and the installation interface and sealing method are checked according to project requirements.

Where biological risks are involved, selection, maintenance and verification should follow the applicable specifications and management documents of the project. The specific configuration is subject to the confirmed technical data and acceptance conditions.