Clean rooms must be validated prior to operation. This process ensures that the clean room is working correctly. The criteria that must be measured in order to validate a clean room include: the volume and quality of air supplied, air movement between the clean room and other rooms, air movement within the clean room and the particle counts in the clean room, including microbiological if necessary. Specific standards set the requirements for clean room validation. These include BS EN ISO 14644-1:1999 "Cleanrooms and associated controlled environments. Classification of air cleanliness ".
After a clean room is validated and becomes active it must regularly be checked in order to ensure that it continues to meet initial standards. Specific standards list the time intervals at which clean rooms should be tested and the minimum requirements a clean room must meet.