Viable Monitoring · Non-Viable Monitoring
Environmental Monitoring
What is the difference between viable and non-viable sampling?
Viable Monitoring
Viable air sampling refers to sampling the air to check viable particles. A viable particle contains one or more living microorganisms such as germs, bacteria, mold spores or yeast.
These can affect the sterility of the pharmaceutical product and generally range from around 0.2 µm to around 30 µm in size. The method of monitoring these particles is by capturing, colonizing and counting them.
Two technologies are used:
- Settled Plates: used to measure the number of microorganisms settling from the air onto a surface area over time. Plates are placed in positions of interest around the cleanroom, collected after several hours, incubated, and the resulting colonies counted.
- Air Samplers: used to sample microorganisms in air. The volume sampled is usually 1 m³ or cfu/m³. Microorganisms are collected by impaction and later incubated and counted.
Non-viable Monitoring
A non-viable particle is a particle that does not contain a living microorganism but can act as transportation for viable particles.
Non-viable particles are monitored using particle counters. These instruments do not distinguish between viable and non-viable particles, but they are technically advanced and use optics, mirrors, a laser, a sensor and a pump to size and count particles.
The bigger the particle, the more light it reflects and therefore the larger the electrical pulse converted by the photo detector.
Why are 0.5 and 5.0 micron particles measured?
During non-viable particle monitoring, 0.5 and 5.0 micron particles are measured because commonly found bacteria are often in this range and can be transported from one area to another by air movement. Larger particles tend to settle more easily.
How to measure?
Current standards define airborne particle monitoring in particles per cubic meter. Sampling one cubic meter with a conventional 1 CFM / 28.3 LPM aerosol particle counter requires more than 35 minutes. Higher flowrate devices reduce the time required to certify the ISO class environment.
