Over the past few years there has been an increasing trend to change from previous classification systems used to the ISO classification systems in ISO 14644-1. However, many companies have continued to use the traditional Class 100, 10,000, 100,000 room classification system from Federal Standard 209-e. In Europe, the GMPs utilize another system—Grades A through D.
Many global companies choose to use this classification system. All of these systems are acceptable for use. However, we have also tended to link the systems together, e.g., ISO 5/Class 100/Grade A. This type of linkage is seen in the FDA’s Guidance for Aseptic Processing (2004). If you are manufacturing an aseptic product and use this linked classification system it is not likely to be an issue. However, if you are not manufacturing an aseptically processed product, choosing to link the classification systems together may lead to other consequences.
The ISO 14644-1 classification system, which replaced Federal Standard 209e, establishes the certification requirements for air cleanliness areas. Within this document the various classification systems are based upon the requirements for counts associated with non-viable particulates. In the FDA’s Guidance for Industry—Sterile Drug Products Produced by Aseptic Processing—Current Good Manufacturing Practice (2004)—which is limited in scope to the manufacture of medicinal products using aseptic processing—there is a similar chart which includes the requirements for both viable and non-viable microbial counts as part of the classification system.