In Reply to Parent Post by carlosandrosie
Based on my findings it seems that there is no regulatory requirement for device manufacturers other than establishing your own limits, but I want to believe there is more than just setting them somehow arbitrarily based on historic data.
The guidance you are looking for can be found in ISO14698 Pts 1 & 2, "Cleanrooms and associated controlled environments - Biocontamination control". Part 1 is the guide to how to set up a system, including methods of detection, how to set effective limits and system verification. Part 2 is about the evaluation and interpretation of the data you generate. Both parts offer excellent guidance on managing levels of cleanroom bioburden.
The only true arbiter of the performance limits is you. What performance level do you need to protect your products adequately? What did you manage to acheive in the manned state during PQ or PV? Are you able to consistenly reach those levels or has the perfromance of the room wandered from the validated state?
If you are want guidance on "normal" room performance limits then Annex 1
of the EudraLex "rules governing medicinal products in the EU", Volume 4 EU guidance to GMP
is the only standard I know of that spells out specific performance limits - I attach that table as a picture, but the document is freely available from the link above. The stated room grades align with the US room classifications as follows Grade A = class 100 (aseptic), Grade B = class 100 (non-aseptic), Grade C = class 10,000 and Grade D = class 100,000. Although this is a pharma standard, there is no reason that any cleanroom operating to these classifications should not be able to meet these performance limits - I believe the Grade C & D limits are very generous.
Hope this helps,