Cleanrooms play a critical role in pharmaceutical manufacturing by controlling airborne particulate levels and supporting contamination control. Cleanrooms may differ in design, function, and regulatory framework, but their air cleanliness is commonly described using ISO 14644 classifications or, for sterile medicinal products under EU GMP Annex 1, Grades A through D.
This article explains the cleanroom classifications and grades most commonly encountered in pharmaceutical facilities, how the systems relate, and how testing supports qualification and ongoing control.
Why Cleanroom Classification Matters in Pharma
Pharmaceutical products, especially sterile and aseptically processed drugs, can be highly sensitive to contamination. Air-cleanliness classifications provide a standardized way to establish and verify airborne particle control as part of a broader contamination-control program.
Classification is used to:
- Establish airborne cleanliness targets for controlled spaces
- Establish appropriate testing and monitoring programs
- Demonstrate control during audits and inspections
- Align facility design and operation with product risk
ISO Cleanroom Classifications
The global framework for cleanroom classification is defined in ISO 14644-1, which classifies cleanrooms based on the concentration of airborne particles per cubic meter at specified particle sizes.
ISO cleanroom classes range from ISO Class 1 (most stringent) to ISO Class 9 (least stringent). In pharmaceutical facilities, the classes most commonly encountered are:
- ISO Class 5
Commonly used for critical zones where sterile product, components, or critical surfaces may be exposed, including many aseptic processing and sterile compounding applications. - ISO Class 7
Commonly used for cleanroom processing areas and as a background environment supporting ISO 5 critical zones in many aseptic applications. The appropriate classification depends on the process and regulatory framework. - ISO Class 8
Often applied to controlled support areas where a lower level of airborne particulate control is appropriate, depending on process risk and applicable requirements.
ISO classification is determined through nonviable particle counting in a defined occupancy state, such as as-built, at-rest, or operational, as agreed for the facility and its intended use.
EU GMP Cleanroom Grades
EU GMP Annex 1 defines Grades A through D for cleanrooms and clean zones used in the manufacture of sterile medicinal products. Annex 1 uses ISO 14644-1 methodology for cleanroom classification, but its grades also reflect process use and contamination-control expectations, so they should not be treated as simple one-to-one ISO equivalents.
At the >=0.5 micrometer particle size used for Annex 1 classification, the grade limits correspond approximately to:
- Grade A: ISO Class 5-level limit at rest and in operation
- Grade B: ISO Class 5-level limit at rest and ISO Class 7-level limit in operation; used as background to Grade A for aseptic preparation and filling when not using isolator technology
- Grade C: ISO Class 7-level limit at rest and ISO Class 8-level limit in operation
- Grade D: ISO Class 8-level limit at rest; Annex 1 does not prescribe a fixed in-operation classification limit
These comparisons describe airborne particle limits, not full equivalence between the two systems. Annex 1 also establishes requirements for cleanroom qualification, environmental and process monitoring, airflow visualization, microbial control, and contamination-control strategy.
Classification vs. Cleanroom “Type”
Terms such as modular, hardwall, softwall, unidirectional, and non-unidirectional describe cleanroom construction or airflow design. ISO classes and EU GMP grades describe cleanliness or regulatory performance. A pharmaceutical cleanroom may therefore have both a design type and a required classification or grade.
Keeping those concepts separate helps teams specify the room around its process, contamination-control strategy, and applicable regulatory requirements.
Cleanroom Testing and Certification
Pharmaceutical cleanroom qualification and periodic certification typically evaluate both airborne cleanliness and the controls that support it. Depending on the room, process, and applicable requirements, testing may include:
- Nonviable particle counting
- Airflow velocity and volume testing
- HEPA filter integrity testing
- Room pressure differential verification
- Temperature and relative humidity measurement
Nonviable particle counting verifies the specified air-cleanliness class or grade. The additional tests evaluate supporting systems and facility performance, providing evidence that the cleanroom remains suitable for its intended use.
Partnering with TSS
Technical Safety Services supports pharmaceutical manufacturers with cleanroom testing, certification, and qualification services for facilities operating under ISO 14644, EU GMP, and cGMP requirements. With nationwide coverage and an ISO 9001-certified quality system, TSS helps clients generate objective test data to verify cleanroom performance throughout the facility lifecycle.
Conclusion
Pharmaceutical cleanrooms can be described by construction, airflow design, ISO classification, or regulatory grade, but those terms answer different questions. Understanding the applicable classification or grade, and verifying it through an appropriate qualification and monitoring program, is fundamental to contamination control and product quality.
For sterile manufacturing in particular, ISO particle classification is only one part of the overall state of control; the broader program also considers facility design, airflow, filtration, environmental monitoring, cleaning, personnel practices, and process risk.
For more information about our cleanroom capabilities or to get started on a new project, please contact TSS today.
