Zone concept ISO 14644

Hi together
I have a question regarding a zone concept for a production room that is currently ISO 9 but has a few ares (over equipment) with ISO 8 status that are separated by a displacement airflow over 0.2 m/s.

I want to replace ISO 9 by CNC (controlled not classified) as the only reason why we have ISO 9 is that there is ISO 8 in the same room. ISO 8 is verified annually.
My question: Does the existence of the ISO 8 zone necessarely require that there is ISO 9 around?
Or can I also ensure the ISO 8 requirements with my CNC zone that fullfills ISO 9 requirements but does not need the annual verification as ISO 9?
I cannot find a clear regulatory statement regarding the transition from ISO 8 to ISO 9 or controlled environment.
Can anyone help me out?

Really interesting question, I hope I can help you and that other may correct me if I am wrong.

So far I know ISO 9 classification does not exist since 2001.
ISO 8 Nearest Equivalent in US FDA 2004 Aseptic Processing Guidance is Grade C.

So far ISPE/ISO mention in ISPE Baseline® Guide: Sterile Product Manufacturing Facilities that the area should be sealed with caulk to prevent contamination between areas, with escutcheon plates suggested.

I do not understand your current situation/application but a CNC area to a ISO 8 area should be separated.
Also a positive room pressure from the high to low classification should be applied.

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