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Cleam-room classes and standards

Cleanrooms are classified by ISO clean-room classes. The ISO 14644-1 specifies the account of particulates, depending on their size, that may be contained in 1m³ of air. These maximum allowed concentrations must not be excessed for the respective ISO rating. The lowest ISO rating is ISO class 9; the highest rating is ISO class 1.
In some cases, particularly in the areas of food technology and pharmacy, air quality is rated by the account of microorganisms or germs (colony forming units). In pharmacy, EC-GMP Annex 1 is used for this rating.

By means of standardised measuring methods, particle or germ concentrations are being controlled in order to assign the according clean-room classes. This way, air quality can be rated and becomes a standardised value.

The table below shows ISO clean-room classes 1 to 9; the demands of EC-GMP as far as germs are concerned; and the obsolete US Federal Standard 209E which is invalid since 2001.

Table of clean-room classes

Effective standard									Revoked / old standard
DIN EN ISO 14644-1							EC-GMP		US Federal Standard 209E
Clean-room class	Cn=maximum count particles per cubuc metre and particle diameter						Room classification	Colony forming units CFU/m³	English unit ft³	Metric SI unit m³
Clean-room class	0.1 µm/m³	0.2 µm/m³	0.3 µm/m³	0.5 µm/m³	1.0 µm/m³	5.0 µm/m³	Room classification	Colony forming units CFU/m³	English unit ft³	Metric SI unit m³
ISO 1	10	2
ISO 2	100	24	10	4
ISO 3	1000	237	102	35	8				1	M 1.5
ISO 4	10000	2370	1020	352	83				10	M 2.5
ISO 5	100000	23700	10200	3520	832	29	A / B	<1	100	M 3.5
ISO 6	1000000	237000	102000	35200	8320	293	(B)	10	1000	M 4.5
ISO 7				352000	83200	2930	C	100	10000	M 5.5
ISO 8				3520000	832000	29300	(C)/D/E/F	200	100000	M 6.5
ISO 9				35200000	8320000	293000	incl. employees

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Cleam-room classes and standards

Table of clean-room classes

Effective standard

Revoked / old standard