Passive and active cleanroom air monitoring

  1. Clean room microbiological testing:

Currently, clean rooms are used in many fields such as pharmaceuticals, food, etc. These industries have high requirements for the density of dust and microorganisms in the air, these two parameters need to be strictly controlled and checked regularly.

Pic 1: Cleanroom

Cleanroom classes are divided according to the amount of dust particles of a specified size suspended in the air; it is accepted that the fewer particles in the air, the more controlled the environment is and the less likely it is to harbor microorganisms. Environmental monitoring needs to be implemented appropriately in terms of sampling locations, number of sampling locations, and sampling frequency. In addition, the sampling plan needs to be changed rather than fixed to more accurately reflect the environmental impact. environmental situation.

Pic 2: 90mm disc for air microbiology testing

  1. Passive and active air monitoring:
    • Passive air monitoring: A method of using an open environmental agar plate placed at the test location for a certain period to check the amount of particles (with or without attached bacteria) falling in.

    –           The advantage of this method is that it is simple and easy to perform, and can monitor the amount of microorganisms falling into the environmental plate as in normal conditions.

    –           The disadvantage is that the method takes longer than active air monitoring.

    –           How to do it: Prepare a Petri dish with an environment suitable for the microbiological object to be tested (eg TSA for bacteria, SDA for yeast and mold). Open the plate at the sampling location and leave it for a certain time (for example 1 hour), then incubate and read the results.


    • Active air monitoring: A method of using support equipment to suck air into the agar plate, and survey the amount of microorganisms attracted and attached to the environmental plate, shortening the implementation time.

    –           The advantage of this method is that the implementation time is shorter than the passive method of determining the test air volume.

    –           Disadvantage: This method is not suitable for checking the number of microorganisms in the air falling on the product under natural conditions because the machine sucks the air in the vicinity of the sampling location and also sucks up suspended particles that do not tend to occur. falling direction.

    –           How to do it: Prepare a petri dish similar to passive sampling, put the dish in the machine and start, inhale, and then incubate it.

    1. Conclusion:

    With the above advantages and disadvantages, it is necessary to consider the appropriate testing needs of each facility to choose one of the two methods or combine both to get air testing results that accurately reflect the clean room situation.

    90mm disc for air microbiology testing:

    • TraceMedia™ Sabouraud Dextrose Agar (SDA) : Ready-to-use medium on 90mm petri dishes for fungal culture.

    • TraceMedia™ Tryptone Soy Agar: Ready-to-use medium on 90mm petri dishes for non-selective cultivation of easily grown bacteria.


0978 782 147