This ISO standard includes these clean room classes : ISO 1, ISO 2, ISO 3, ISO 4, ISO 5, ISO 6, ISO 7, ISO 8 and ISO 9. ISO 1 is the “cleanest” class and ISO 9 is the “dirtiest” class. Even if it’s classified as the “dirtiest” class, the ISO 9 clean room environment is cleaner than a regular room.
The most common ISO clean room classes are ISO 7 and ISO 8. The Federal Standard 209 ( FS 209E ) equivalent for these ISO classes are Class 10,000 and Class 100 000.
The old Federal Standard 209E ( FS 209E ) includes these clean room classes : Class 100,000; Class 10,000; Class 1,000; Class 100; Class 10; Class 1. This standard was replaced in 1999 by ISO-14644-1. It was withdrawn in 2001, but it is still widely used.
Clean rooms must also follow industry-specific and international standards. For example, EU GMP (A-B-C-D), applies to pharmaceutical products and USP (795, 797 and 800) to compounding pharmacies.










