Understanding ISO & GMP Cleanroom Standards

What Cleanroom Standards Do

Cleanroom standards govern both how cleanliness is measured and how it is maintained in daily operation.

ISO 14644 focuses on airborne particulate cleanliness. It sets the criteria for measuring airborne particle concentrations, testing procedures, and verification. These standards apply across all cleanroom industries, ensuring that air cleanliness is quantifiable and comparable worldwide.

Good Manufacturing Practice (GMP) provides a regulatory framework for the production of medicines and sterile products. It extends beyond air cleanliness to include layout, personnel practices, materials, documentation, and quality assurance systems. In the UK and EU, the key reference is EU GMP Annex 1, which defines the environmental and procedural controls required for sterile product manufacture.

In essence: ISO 14644 measures and maintains environmental control, while GMP governs how facilities and processes protect product quality and patient safety.

ISO 14644 Explained

The ISO 14644 family spans the full lifecycle of a cleanroom. The most used parts are:

• Part 1 – Classification: Defines ISO Classes 1–9 for airborne particulate cleanliness and describes how to measure and verify them.
• Part 2 – Monitoring: Establishes expectations for continuous, risk-based environmental monitoring.

Other parts address design, construction, surface cleanliness, and cleaning methods. For a panel manufacturer like Gilcrest, relevant factors include the cleanroom envelope — wall, ceiling, and door systems — and how their design supports airflow uniformity, cleanability, and avoidance of particle traps.

Cleanrooms may be classified as built, at rest, or in operation — defined respectively as before installation of equipment, after installation but without personnel, and during normal working conditions with both equipment and operators present. Core tests include airborne particle counting, airflow visualisation, HEPA filter integrity testing, and pressure differential checks.

GMP and EU Annex 1

Good Manufacturing Practice ensures medicinal products are consistently produced and controlled. In Europe, sterile manufacture follows EU GMP Annex 1, enforced by the MHRA. Annex 1 requires a documented Contamination Control Strategy integrating building design, gowning, cleaning, utilities, and monitoring.

Annex 1 Update: The revised Annex 1 came into force in August 2023 following its 2022 publication. It emphasises contamination control strategy, protection of first air, airflow visualisation, and data integrity — affecting both facility design and qualification expectations.

Grade A is used for critical aseptic operations such as filling and open connections, Grade B supports these zones, Grade C handles component preparation, and Grade D covers support activities such as washing and weighing.

ISO and GMP Together

While ISO and GMP frameworks serve different purposes, there is practical overlap. For example, a Grade A environment typically achieves ISO 5 conditions at rest, Grade B is ISO 6 or 7, and Grades C and D correspond roughly to ISO 7 and 8. These comparisons are indicative only; Annex 1 limits take precedence, as GMP grades regulate viable and operational control rather than airborne-particle counts.

Designing a Compliant Facility

Layout and Flows

• Establish a pressure cascade from lower to higher cleanliness (typically 5–15 Pa differentials).
• Separate personnel and material routes using interlocked airlocks.
• Design flush finishes with minimal ledges or recesses to avoid contamination traps.

Cleanroom Envelope

Select a system engineered for hygienic performance:

• Smooth, non-shedding, non-porous surfaces
• Flush-fitted windows and doors
• Coved skirting and ceilings for easy cleaning
• Documented compatibility with disinfectants and vapour-phase agents

Aluminium honeycomb panel systems such as Puracore® provide rigidity, flatness, and cleanability suited to ISO- and GMP-regulated environments.

Air Handling

• Match HEPA grade and configuration to the ISO class.
• Verify airflow and pressure differential during qualification.
• Demonstrate first-air protection with smoke visualisation.

Noise may be considered in facility design, though acoustic treatment typically falls outside GMP scope.

Qualification and Validation Roadmap

Validation proves that a cleanroom performs as intended. Gilcrest supports these processes through design documentation and material traceability, while testing is typically managed by the client or specialist consultants.

1. URS & Risk Assessment – Define ISO classes, GMP grades, and critical parameters.
2. Design Qualification (DQ) – Demonstrate that the design meets the URS.
3. Installation Qualification (IQ) – Verify correct installation and materials compliance.
4. Operational Qualification (OQ) – Confirm performance at rest.
5. Performance Qualification (PQ) – Verify control during normal operation.
6. Ongoing Verification – Re-qualify periodically and trend environmental data.

Environmental Monitoring & Control

Environmental monitoring ensures continued compliance and forms part of the Contamination Control Strategy defined in Annex 1.

• Non-viable monitoring: Particle counting at defined intervals and locations.
• Viable monitoring: Air, surface, and personnel sampling using active air samplers and contact plates.
• Trending and review: Data must be recorded, trended, and reviewed regularly to detect drift or contamination events.

Monitoring verifies that the cleanroom envelope, HVAC system, and operational practices perform as designed.

Common Pitfalls and Why They Occur

Confusing ISO and GMP standards → mismatched classifications and failed audits.

Sector-Specific Considerations

Different industries apply the same principles with varied emphasis:

Pharmaceutical & Biotech: Stringent control under Annex 1 requires focus on aseptic processing, particle shedding mitigation, and microbial ingress prevention. Production delays carry regulatory and compliance costs, driving higher uptime requirements and material durability specifications. Gilcrest panel systems must deliver consistent, validated performance across continuous operational demand.

Semiconductors: Extreme particle sensitivity dominates, but material selection extends beyond ISO classification. Critical considerations include electrical properties (static dissipation, conductivity) and chemical compatibility with process gases and cleaning solvents. Materials also face thermal and humidity cycling stresses that differ from pharma environments. The economic driver is clear: a single particle defect causes yield loss across expensive wafers, justifying the investment in ultra-clean systems.

Aerospace & Optics: Less compliance-driven than pharmaceuticals or life science, but functionally demanding. Material outgassing and thermal stability are critical concerns that can compromise precision optical surfaces or composite lay-up quality. Long qualification cycles and detailed traceability requirements create high barriers to material substitution, making initial material selection crucial.

Gilcrest panel systems are used across these sectors, tailored for the appropriate ISO class and regulatory expectations.

How Gilcrest Supports Project Delivery

1. Define: Map ISO/GMP requirements, pressure cascades, and cleanroom zoning.
2. Design: Specify Puracore walls, ceilings, doors, and flush windows with integrated accessories.
3. Deliver: Manufacture and install panels with minimal on-site cutting to maintain cleanliness.
4. Support: Provide certificates, IQ/OQ documentation packs, and future expansion options.

Working with Gilcrest Manufacturing

Whether designing a new facility or upgrading an existing suite, Gilcrest Manufacturing delivers cleanroom panel systems that align with ISO 14644 and EU GMP Annex 1. Our expertise in cleanroom envelope design ensures fast installation, consistent finishes, and reliable compliance documentation for smooth audits and efficient operation. Discuss the your challenges with us here.