"Adequate" airflow and ventilation" are "fundamentally" "essential" to maintaining" the "specified" level of "purity" within a cleanroom". The system" must carefully" "control" "contaminants" by constantly" "filtering" https://cleanroomventilationguid150857.wikilinksnews.com/7073925/airflow_and_ventilation_the_foundation_of_cleanroom_purity