What is a cleanroom?

A cleanroom is an environment with high cleanness and is designed to reduce or even eliminate contamination (pollution) of product, process or examination within that space. Contamination can consist of large and fine particles present in the air, as well as fibres, micro-organisms and chemical vapours. The degree of contamination in a cleanroom is specified on the basis of the amount of particles of a certain size per cubic metre.

All cleanrooms must meet an international standard ISO14644-1. A new version of this standard has recently been released: the ISO 14644-1:2015 (replacing the old 14644-1:1999). The definition of a cleanroom according to the current ISO standard:

“Cleanroom – Room in which the concentration of airborne particles is controlled and classified, and which is constructed and used in a manner to minimize the introduction, generation and retention of particles inside the area.”

Ref. International standard ISO14644 first edition 2015.

Cleanroom Standard	Cleanroom Classification Guidelines
ISO 14644-1	Class 3	Class 4	Class 5	Class 6	Class 7	Class 8
Federal Standard 209E	1	10	100	1.000	10.000	100.000
EU GGMP	–	–	A/B	–	C	D
Air changes / hour	360-540	300-540	240-480	150-240	60-90	5-48

Selected Airborne Particulate Cleanliness Classes

For cleanrooms and clean zones shown in ISO 14644-1:2015

ISO Classification Number	Maximum concentration limits (particles/m³ of air) for particles equal to and larger than the considered sizes shown below
	≥0.1µm	≥0.2µm	≥0.3µm	≥0.5µm	≥1.0µm	≥5.0µm
ISO Class 1	10	–	–	–	–	–
ISO Class 2	100	24	10	–	–	–
ISO Class 3	1.000	237	102	35	–	–
ISO Class 4	10.000	2.370	1.020	352	83	–
ISO Class 5	100.000	23.700	10.200	3.520	832	–
ISO Class 6	1.000.000	237.000	102.000	35.200	8.320	293
ISO Class 7	–	–	–	352.000	83.200	2.930
ISO Class 8	–	–	–	3.520.000	832.000	29.300
ISO Class 9	–	–	–	35.200.000	8.320.000	293.000

Cleanroom Limits for Airborne Particulate Contamination

Relating to GGMP

Cleanroom Standard		Maximum permitted number of particles /m³
EU GGMP Grade	ISO14644-1:1999	At rest ≥0.5µm	At rest ≥5.0µm	In operation ≥0.5µm	In operation ≥5.0µm
A	5	3.520	20	3.520	20
B	5	3.520	29	352.000	2.900
C	7	352.000	2.900	3.520.000	29.000
D	8	3.520.000	29.000	not defined	not defined