Cleanrooms are classified according to the cleanliness level of the air inside them. The cleanroom class is the level of cleanliness the room complies with, according to the quantity and size of particles per volume of air.
The primary authority in the US and Canada is the ISO classification system ISO 14644-1.
This standard includes the cleanroom classes ISO 1, ISO 2, ISO 3, ISO 4, ISO 5, ISO 6, ISO 7, ISO 8 and ISO 9, with ISO 1 being the “cleanest” and ISO 9 the “dirtiest” class (but still cleaner than a regular room).
The most common classes are ISO 7 and ISO 8.
Cleanrooms must comply with industry-specific and regional standards. For example, EU GGMP (A-B-C-D) applies to pharmaceutical products and USP (795, 797 and 800) to compounding pharmacies.
|ISO 14644-1 Cleanroom Standards|
|Class||maximum particles/m3||FED STD 209E
|ISO 3||1,000||237||102||35||8||Class 1|
|ISO 4||10,000||2,370||1,020||352||83||Class 10|
|ISO 5||100,000||23,700||10,200||3,520||832||29||Class 100|
|ISO 6||1,000,000||237,000||102,000||35,200||8,320||293||Class 1,000|
|ISO 7||352,000||83,200||2,930||Class 10,000|
|ISO 8||3,520,000||832,000||29,300||Class 100,000|
|ISO 9||35,200,000||8,320,000||293,000||Room Air|
|BS 5295 Cleanroom Standards|
|Class||>=0.5 µm||>=1 µm||>=5 µm||>=10 µm||>=25 µm|
Cleanroom classification – Grade A, B, C or D
Grades A through to D refer to cleanroom cleanliness for the Pharmaceutical Industry for European, Australian and some Asian countries.
Grade A is the cleanest, for sterile operations, through to Grade D for packing or support operations. These Grades can be related to the ISO Classes.