During a recent surveillance audit by our certification body we received a nonconformance to ISO 13485 clause 126.96.36.199. Auditor stated "the validation of the clean room "at rest" does not challenge the worst case scenarios of the clean room's intent regarding particle count contamination. The validation for worst case scenario must be done in "Operation". The auditor shared an email from an official at FDA to emphasis his point
We have performed particle counts in "operation" but not routinely. We do use a contracted service to annually certify the cleanrooms. Their Certificates of Compliance certifies our cleanrooms in compliance to air cleanliness classification for an ISO Class 7 under "at rest" conditions, as outlined in ISO 14644-1:1999. We also measure particle counts to verify continued compliance monthly ourselves, also "at rest". We are now considering changing to particle counts to "operation" instead of "at rest" although my understanding is that most folks in the industry perform this monitoring "at rest". Anybody have some insight regarding this practice?