Cleanroom Classification

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
Classmaximum particles/m3FED STD 209E
ISO 1102
ISO 210024104
ISO 31,000237102358Class 1
ISO 410,0002,3701,02035283 Class 10
ISO 5100,00023,70010,2003,520832 29 Class 100
ISO 61,000,000237,000102,00035,2008,320 293 Class 1,000
ISO 7352,00083,2002,930 Class 10,000
ISO 83,520,000832,00029,300 Class 100,000
ISO 935,200,000 8,320,000293,000Room Air
BS 5295 Cleanroom Standards
maximum particles/m3
Class>=0.5 µm>=1 µm>=5 µm>=10 µm>=25 µm
Class 13,000000
Class 2300,0002,00030
Class 31,000,00020,0004,000300
Class 420,00040,0004,000
Cleanrooms Classifications-chart

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.