Settle Plates with a Diameter of 150 mm Can be Exposed to Unidirectional Airflow for up to 8 Hours

Active and passive air monitoring is crucial for gaining knowledge about the microbial status of clean room environments for aseptic processing. Most agencies require active air monitoring of defined volumes in short time periods. However, active air monitoring methods may disrupt the unidirectional airflow of filtered air and are therefore difficult to use for continuous air monitoring. Hence, settle plates are additionally placed at areas of high risk during the whole filling process, including setup. Although EU GMP Annex 1 9.30 defines a maximum duration of 4 hours for settle plates with a diameter of 90 mm, and USP <1116> defines a maximum of 4-5 hours, there are no recommendations for settle plates with a diameter of 150 mm. Agencies expect validation studies, including recovery rates, as a basis to determine the exposure time. This study provides data that show that settle plates with a diameter of 150 mm can be placed under unidirectional airflow for up to 8 hours in a clean room with moderate humidity. No negative effect on the suitability of the media was observed. Moreover, it is shown that settle plates with a diameter of 150 mm can be exposed to unidirectional airflow for up to 6 hours in a clean room with very low humidity as used for aseptic filling of lyophilized products. Increased exposure times of settle plates for up to 6 to 8 hours significantly reduce the exchange frequency of settle plates, which ultimately lowers the risk of microbial contamination during filling due to less interventions.