"Effective" airflow and "aeration" are "fundamentally" critical" to "preserving" the desired" level of "purity" within a "sterile area". The system" must "precisely" "control" "contaminants" by "repeatedly" "filtering" https://cleanroom-ventilation-gu008336.wikinstructions.com/416535/airflow_and_ventilation_the_foundation_of_cleanroom_purity