Cleanroom Grades A/B/C/D
What a definition is not
A definition is SPEQ’s plain-language decode of how a term is used in practice, cited to the documents that define it. It is a practitioner reference, not legal or regulatory advice, it does not replace the definition in the source, and where a regulator’s wording differs the regulator’s wording governs.
EU GMP classifies sterile-manufacturing cleanrooms into grades A, B, C, and D by the maximum permitted airborne particle concentrations and microbial limits, at rest and in operation. Grade A is the critical zone for high-risk aseptic operations; B is its immediate background; C and D are cleaner and less clean support areas.
Grade A (and B at rest) correspond to the most stringent ISO 14644-1 particle class, with grade A requiring unidirectional airflow at a specified velocity over the critical zone. The classification is verified both "at rest" and "in operation," because operator activity dramatically raises particle and microbial burden.
The grade a step is performed in determines both the required environment and the monitoring regime: grade A aseptic filling demands continuous particle monitoring and stringent microbiological action limits, whereas early solution preparation may be acceptable in grade C or D.
- —Grades A/B/C/D set by airborne particle and microbial limits.
- —Grade A = critical zone; B = its background; C/D = support areas.
- —Grade A requires unidirectional airflow at 0.36–0.54 m/s under Annex 1 (2022).
- —Classified both at rest and in operation.
EU GMP Annex 1 (2022) grade table for particle and microbial limits; ISO 14644-1 (2015) particle classification.
Frequently asked questions
What is Cleanroom Grades A/B/C/D?
EU GMP classifies sterile-manufacturing cleanrooms into grades A, B, C, and D by the maximum permitted airborne particle concentrations and microbial limits, at rest and in operation. Grade A is the critical zone for high-risk aseptic operations; B is its immediate background; C and D are cleaner and less clean support areas.
Which regulations cover Cleanroom Grades A/B/C/D?
EU GMP Annex 1 (2022) grade table for particle and microbial limits; ISO 14644-1 (2015) particle classification.