: This is the core document that defines classification of air cleanliness by particle concentration. It specifies the maximum number of particles allowed per cubic meter for classes ISO 1 through ISO 9.
The ISO 14644 family consists of multiple parts, e.g.: iso 146446 pdf
Because these are copyrighted intellectual property, you typically won't find the full, legal text for free on a simple web search. To stay compliant and audit-ready, it is best to obtain the official documents from authorized distributors: for the definitive international version. National Standard Bodies : This is the core document that defines