Monitoring Critical Environments Using Particle Counters With 4-20mA Analog Outputs

As many of you already know, when a particle counter continuously monitors an aseptic manufacturing process, it is positioned to detect potential harm to the product. The purpose is to detect changes, transient events, particle excursions and deviations from processing norms that may pose an increased risk to the product or process. When an excursion occurs that exceeds predetermined action limits, a root cause investigation is performed. Section E of the FDA Aseptic Processing guidance 2004 clearly links the thoroughness of any root cause investigation to the severity of a particle excursion.

Routine particle monitoring is useful in rapidly detecting significant deviations in air cleanliness from qualified processing norms (e.g., clean area classification). A result outside the established classification level at a given location should be investigated as to its cause. The extent of investigation should be consistent with the severity of the excursion and include an evaluation of trending data. Appropriate corrective action should be implemented, as necessary, to prevent future deviations.