Air Monitoring & Cleanroom Monitoring

HEPA FILTER MOUNTED ON AIR SAMPLER

The active viable air samplers for viable contamination monitoring in Cleanroom / Isolator / RABS should not pose a contamination risk during their use.  

The TRIO.BAS microbial air samplers have an electrical motor that do not produces particles after the cleaning procedure during the first initialisation.

They are therefore used in Cleanroom / Isolator / RABS if permanently located in such areas.  If the same air sampler is transferred in different environments with different levels of microbial contamination (from high to low – e.g. from C to A area) a risk of cross-contamination is possible.
In this case, to avoid this risk of transfer of particles from the inside part of instrument aspirating chamber, it is suggested to adopt the  that includes an HEPA filter fixed on the air outlet of instrument for an easy control or on the satellite units of stainless steel family of samplers. The purpose of the filter is to stop the potential transfer of particles.
The HEPA filter is externally positioned and therefore the replacement is very simple.                        

There are many types of microbial air samplers. The most used one is the microbial air sampler based on the impact method on an agar plate (also known as impactor). This type of sampler has 2 main components: an air pump and a head piece. The head piece contains an agar plate. The air pump pulls the air through a perforated cover into the headpiece. The air then makes a short turn above the agar plate. Due to the centrifugal force, the particles in the air make contact with the agar surface and they stick. Micro-organisms always travel on dust or aerosol particles. They rarely travel on their own. By incubating the agar plate after the sampling, the micro-organisms will multiply. After a certain incubation time, the clusters of bacteria are visible on the plate, and the so called colony forming units can be counted. Based on the volume of sampled air, you can then calculate the number of colony forming units present per volume of air. This method is the most used for the so called ‘active air sampling’ or ‘viable particle monitoring’.

This method has a large advantage when you do routine microbial quality control of the air. The most common used parameters for this are total viable count, and total yeasts and moulds. Usually, you have an idea of the range of colony forming units in the air, and you only want to measure cultivable micro-organisms. Using the microbial air sampler by impact on agar you have a very fast, easy, and cheap method to monitor the air quality. You sample directly on the plate, incubate, and count it. Culturing is the most easy and cheap detection method. It is widely used in different industries and guidelines.

The EU GMP Annex 1 is a guideline for the sterile production (in pharma and biotech production environments). The EU GMP Annex 1 has a section that talks about ‘Viable and non-viable environmental & process monitoring’. Air monitoring is a big part of this section. The guideline talks about 3 types of air monitoring:

• Passive sampling of viable particles/ settle plates: this is a simulation of the reality. You open the agar plate for max 4 hours, you close it, incubate it, and at the end you can count the colonies.
• Volumetric air sampling / active air sampling of viable particles: this is most often done with an impactor/ microbial air sampler. You sample max 1000L per plate. After that, you incubate the plate, and you count the colonies. This gives you exact data about the number of viable particles per volume of air.
• Monitoring of non-viable particle: for this part, you measure the number of dust particles of <0,5 µm and <5µm using an air sampling instrument (often referred to as particle counters).

For all 3 types of air monitoring mentioned above, the EU GMP Annex 1 defines certain thresholds for the different cleanroom grades: grade A, B, C and D. Also, the frequency of the sampling depends on the cleanroom grade. For grade A zones, the microbial air samples must be in stainless-steel an often satellite samplers or probes are used.

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