ISO 14644 - Part 1: The Long-Awaited Final Version on Cleanroom Classification
Recommendation

22/23 September 2026
Organisation of a GMP-compliant Site Change
Part 1 of ISO 14644 entitled "Classification of air cleanliness by particle concentration" is one of the most important norms in the GMP environment as it is the only technical norm which is directly referred to in an official GMP guideline document: the currently applicable Annex 1 of the EU GMP Guide. This norm is decisive and has to be used for the classification of cleanrooms used for GMP production. It contains the tables of cleanroom classes and their respective maximum of permitted number of particles as well as instructions on how to perform particle measuring.
The revision of the norm had already started in 2007. Many drafts have been published, e.g. in 2011, 2012, 2014 and 2015 but not a single one of them could achieve the final status. All the time, the version of 1999 has been applicable.
Now, since the end of 2015, the final version in English of the ISO 14644-1 is available from the publisher Beuth.
Substantially, the new version includes the following changes:
- The number of measuring points is no longer calculated as the square root of the surface but given in a table.
- 5 µm particles for ISO 5 has been dropped from the limit value table.
- No more statistical UCL calculation: there is no need to perform an observation of all measuring points in the room any longer. Each single measuring point is considered individually and has to meet the limit value.
- The tubing length to the particle counter should be less than 1 m.
- The classification number, the sample volumes/ measuring period as well as the cancellation criterion remain unchanged compared to the version of 1999.
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