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 cleanroom 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 set-up. While EU GMP Annex 1 9.30 defines a maximum duration of 4 hours for settle plates with a diameter of 90 mm and defines a maximum of 4 to 5 hours respectively, 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 showing that settle plates with a diameter of 150 mm can be placed under unidirectional airflow for up to 8 hours in a cleanroom 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 cleanroom with very low humidity as used for aseptic filling of lyophilized products. Increased exposure times of settle plates for up to 6 respectively 8 hours significantly reduce the exchange frequency of settle plates, which ultimately lowers the risk from microbial contamination during filling due to less interventions.