Cleanrooms and Associated Controlled Environments — Classification of Air Cleanliness by Particle Concentration
Establishes the classification of air cleanliness in terms of concentration of airborne particles in cleanrooms and clean zones. Defines ISO Classes 1–9 with associated particle concentration limits and classification testing protocols.
What this does not cover
stated in the document's own scope- Classifies airborne particulate cleanliness only; ongoing monitoring to show a cleanroom stays in classification is the subject of ISO 14644-2.
- Covers particle concentration, not microbiological (viable) contamination — microbial limits for pharmaceutical cleanrooms come from GMP frameworks such as EU GMP Annex 1.
- Sets the classification method, not the design and construction of the cleanroom, which are addressed in other parts of the ISO 14644 series.
- Does not itself set the grade a given operation requires; that is dictated by the applicable GMP for the process.
Always verify against the current published text before relying on it for a submission or inspection.
Overview
ISO 14644-1:2015 is the international standard that classifies the cleanliness of air in cleanrooms and clean zones by the concentration of airborne particles. It defines the ISO classes — ISO Class 1 (cleanest) through ISO Class 9 — each set by maximum permitted concentrations of particles at or above specified sizes, and it prescribes the method for demonstrating that a cleanroom meets a chosen class: the number and location of sampling points, the sample volume, the airborne-particle counter, and the statistical treatment of the results. It also defines the occupancy states — as-built, at-rest, and operational — at which a classification applies.
Scope & applicability
All cleanroom operators in pharmaceutical, semiconductor, aerospace, and other critical manufacturing industries. Provides the universal basis for cleanroom classification referenced by EU GMP, FDA, and national regulations.
Legal basis & how it acquires force
ISO 14644-1 is a voluntary consensus standard published by ISO; it carries no legal force on its own. It acquires authority by being referenced. EU GMP Annex 1 (Manufacture of Sterile Medicinal Products) cites ISO 14644 for the classification and qualification of cleanrooms, mapping its own Grades A–D to particle limits, and national and regional GMP frameworks and USP informational chapters likewise reference it. So a manufacturer meets the binding GMP requirement, and ISO 14644-1 supplies the harmonised classification method that requirement relies on.
Document structure
| Part | Covers |
|---|---|
| Scope and terms | What the standard classifies (airborne particle cleanliness) and the defined terms, including occupancy states |
| Classification (ISO classes) | The ISO Class 1–9 designations and the maximum particle-concentration limits by particle size |
| Demonstration of compliance | The procedure for determining classification, including the required sampling and evaluation |
| Annex A — sampling locations | Determining the minimum number and location of sampling points from the zone area |
| Annex B — statistical evaluation | Calculating results and the 95% upper confidence limit where required |
| Annexes C–D — counting and macroparticles | The particle-counting method and guidance for particles outside the standard size range |
Key requirements
- Particle counter calibration and performance verification before classification testing
- Minimum number of sampling locations calculated from cleanroom area using Table 1
- Sampling volumes at each location sufficient to detect 20 particles at the class limit (U95)
- Statistical analysis (95% Upper Confidence Limit) of data
- Classification report with all data, calculations, and deviations noted
Implementation tips
- EU GMP requires both at-rest and in-operation classification — document which state each result represents
- Particle counters must be calibrated to ISO 21501-4 — confirm your calibration certificate references this
- Create a classification map showing all sample locations with distances to walls and process equipment
Revision notes
Current version December 2015 — revised from 1999 version. Sample size calculation methodology changed significantly. Verify existing classification protocols use 2015 methodology.
Where this control fails
live FDA enforcementLive FDA recalls SPEQ maps to this standard’s topics — a SPEQ interpretation, not an FDA classification.
International alignment
ISO 14644-1 is the classification anchor for a family of ISO 14644 parts covering monitoring (Part 2), test methods (Part 3), design and construction, operations, and related topics. It is the method referenced by EU GMP Annex 1 and by USP informational chapters on controlled environments, and it superseded the earlier US Federal Standard 209E, whose "Class 100 / 10,000" designations map onto the ISO scale.
ISO 14644-1: frequently asked questions
Quick answers to common questions about ISO 14644-1.
What are the ISO classes in ISO 14644-1?
The standard defines ISO Class 1 through ISO Class 9, where ISO Class 1 is the cleanest. Each class is set by maximum permitted concentrations of airborne particles at or above specified sizes.
What are the occupancy states in ISO 14644-1?
Three: as-built (complete, services connected, no equipment or people), at-rest (equipment installed and operating, no personnel), and operational (functioning with personnel present). A classification is stated for a defined state.
How does ISO 14644-1 relate to EU GMP Annex 1 grades?
Annex 1 references ISO 14644 for classifying and qualifying cleanrooms and maps its Grades A–D to particle-concentration limits. ISO 14644-1 supplies the classification method; Annex 1 sets the GMP grade each activity requires.
Did ISO 14644-1 replace Federal Standard 209E?
Yes. The former US Federal Standard 209E was cancelled and its "Class 100 / Class 10,000" designations are now expressed on the ISO scale (for example, Class 100 corresponds broadly to ISO Class 5).
This standard in practice
Recall domain is a SPEQ mapping of this standard’s topics, not an FDA classification.