EU-GMP Annex 1 (2022) defines four pharmaceutical cleanliness grades (A, B, C, D) tied to specific airborne particle limits, while ISO 14644-1 classifies cleanrooms numerically (ISO 1-9) by particle concentration. The two systems align closely: Grade A and B at-rest ≈ ISO 5, Grade C ≈ ISO 7, Grade D ≈ ISO 8. Annex 1 adds GMP requirements ISO does not — in-operation monitoring, microbial limits, and a Contamination Control Strategy.
Key takeaways
- ISO 14644-1 classifies by particle count only; EU-GMP Annex 1 adds microbial limits, in-operation states, and qualification requirements.
- Grade A/B ≈ ISO 5 at rest; Grade C ≈ ISO 7; Grade D ≈ ISO 8 — but in operation the grades diverge.
- The 2022 Annex 1 mandates a formal Contamination Control Strategy (CCS) and reinforces ≥0.5 µm and ≥5.0 µm monitoring.
- GCC regulators (SFDA, MOHAP, DHA, DoH, MoPH) recognise EU-GMP and ISO 14644, so design to both.
- Cleanrooms should be built and validated to the worst-case in-operation grade, not just the easier at-rest state.
Two Standards, One Cleanroom: How They Differ
ISO 14644-1 and EU-GMP Annex 1 measure the same air, but they answer different questions. Confusing them is the single most common cause of failed qualification in pharmaceutical projects across the Gulf.
ISO 14644-1 is an international cleanliness classification standard. It tells you how many airborne particles of a given size are permitted per cubic metre, and assigns a class number from ISO 1 (cleanest) to ISO 9. That is all it does — it is particle-count classification, nothing more.
EU-GMP Annex 1 (2022) is a Good Manufacturing Practice guideline for sterile and aseptic medicinal products. It borrows ISO's particle logic but wraps it in pharma-specific requirements: microbial (viable) limits, defined operational states, gowning, airflow visualisation, and an overarching quality framework.
| Aspect | ISO 14644-1 | EU-GMP Annex 1 (2022) |
|---|---|---|
| Purpose | Particle classification | GMP for sterile manufacturing |
| Labels | ISO 1 to ISO 9 | Grade A, B, C, D |
| Particle limits | Yes (0.1-5.0 µm) | Yes (0.5 & 5.0 µm) |
| Microbial limits | No | Yes (cfu) |
| Operational states | At rest only (for classification) | At rest AND in operation |
| Airflow/CCS | No | Yes (CCS mandatory) |
In short: every Annex 1 grade can be expressed as an ISO class, but not every ISO classification satisfies Annex 1. You design to ISO, you qualify to GMP.
At-Rest vs In-Operation: The State That Changes Everything
The biggest source of error is treating a cleanroom grade as a single number. Annex 1 defines two occupancy states, and the particle limits differ dramatically between them.
- At rest: the room is complete, equipment installed and running, but no operators present and no production. This is the easier, cleaner state.
- In operation: the room is functioning as intended, with the specified number of personnel working and the process generating particles and microbes. This is the harder, real-world state.
ISO 14644-1 classification is normally performed and reported in a defined occupancy state (often at rest). Annex 1 requires you to demonstrate compliance in both states — and crucially, Grade A and B must hold the same particle limit in both, because that is where sterile product is exposed.
Why this matters for design
A Grade C room at rest behaves like ISO 7. The same room in operation is permitted to relax to ISO 8 limits — but it must still recover quickly. If you size HVAC, air changes, and filtration only for the at-rest state, the room will fail in operation when staff and equipment load the air. Always engineer for the worst-case in-operation condition, then verify the at-rest state is comfortably cleaner.
The Mapping Table: Grades A-D to ISO Classes
Here is the practical cross-reference pharma engineers actually use. The maximum permitted particle concentrations (particles/m³) come from Annex 1 (2022), with the equivalent ISO 14644-1 class noted.
| Grade | State | ≥0.5 µm (per m³) | ≥5.0 µm (per m³) | ≈ ISO 14644-1 |
|---|---|---|---|---|
| A | At rest & in operation | 3,520 | 20 | ISO 5 |
| B | At rest | 3,520 | 29 | ISO 5 |
| B | In operation | 352,000 | 2,900 | ISO 7 |
| C | At rest | 352,000 | 2,900 | ISO 7 |
| C | In operation | 3,520,000 | 29,000 | ISO 8 |
| D | At rest | 3,520,000 | 29,000 | ISO 8 |
| D | In operation | Not pre-defined* | Not pre-defined* | — |
*For Grade D in operation, Annex 1 expects limits to be set from the Contamination Control Strategy and risk assessment rather than a fixed table value.
Note the pivot: Grade B is ISO 5 at rest but ISO 7 in operation — the same room, two different ISO classes depending on state. This is exactly why a single ISO number can never fully describe a GMP cleanroom.
For a typical sterile fill-finish suite you would specify a Grade A zone (unidirectional airflow over the open product) within a Grade B background, surrounded by Grade C/D support areas — a layered cascade of pressure and cleanliness.
What Changed in the 2022 Annex 1
The 2022 revision of Annex 1 (in force since August 2023) was the most significant update in over a decade. The particle tables stayed broadly aligned with ISO, but the philosophy shifted. Key changes:
- Contamination Control Strategy (CCS): A formal, holistic, site-wide CCS is now mandatory. It links facility design, equipment, utilities, personnel, and monitoring into one documented system rather than isolated controls.
- Quality Risk Management (QRM) front and centre: Decisions on grades, monitoring locations, and limits must flow from documented risk assessment.
- 5.0 µm clarity: The treatment of the ≥5.0 µm particle size for Grade A/B was clarified, removing the earlier ambiguity around macroparticle counting at the cleanest grades.
- Barrier technology emphasis: RABS (Restricted Access Barrier Systems) and isolators are strongly encouraged for aseptic processing to separate operators from product.
- Pre-Use Post-Sterilisation Integrity Testing (PUPSIT): Reinforced expectations for sterilising-grade filter integrity testing.
- Continuous, holistic monitoring: Greater emphasis on environmental monitoring programmes designed around process risk, not just fixed sampling.
What it means in practice
A modern Annex 1 cleanroom is no longer just a clean box that passes a particle count. It is a documented, risk-justified contamination-control system. Our cleanroom designs are engineered to be validation-ready and compliant with the 2022 Annex 1 framework — see our cleanroom services for design, build, and qualification support.
What This Means for GCC Pharma Cleanrooms
Gulf pharmaceutical manufacturers and importers face a converged regulatory landscape. EU-GMP and ISO 14644 are the de-facto references that regional authorities recognise and inspect against.
- Saudi Arabia (SFDA): GMP inspections reference EU-GMP principles; sterile facilities are expected to meet Annex 1-grade controls and ISO 14644 classification.
- UAE (MOHAP, DHA, DoH): Federal and emirate-level licensing aligns with international GMP; cleanroom classification follows ISO 14644 with GMP grading.
- Qatar (MoPH): Recognises EU-GMP and WHO GMP for sterile and non-sterile manufacturing.
- WHO GMP & GSO: Provide additional baselines for regional registration and Gulf conformity.
For a project to pass inspection and product registration in the GCC, the cleanroom should be designed to ISO 14644, qualified to EU-GMP Annex 1, and documented under a CCS from day one. Retrofitting GMP compliance into an ISO-only build is expensive and slow.
Practical build guidance for the Gulf
Climate matters. Gulf ambient conditions — high heat, humidity, and dust — place heavy load on HVAC, makeup-air handling, and pre-filtration. A cleanroom that holds Grade C in a temperate climate needs additional cooling and dehumidification capacity to hold the same grade in Dammam, Dubai, or Doha. Specify panels, doors, and filtration rated for the in-operation worst case under Gulf load.
Pak Gusu manufactures cleanroom systems in Pakistan and ships across the GCC (Incoterms CIF/DAP via Jebel Ali, Dammam, and Hamad), with installation available at extra cost. Explore our cleanroom panels, see how this applies to pharmaceutical and nutraceutical facilities, or compare regional pricing on our cleanroom cost guide.
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Frequently Asked Questions
Common questions about cleanrooms, standards, cost and how Pak Gusu supplies and installs across the GCC.
What is the difference between EU GMP grades and ISO 14644 classes?
ISO 14644 classifies cleanrooms purely by airborne particle count (ISO 1-9). EU-GMP Annex 1 grades (A-D) use similar particle limits but add pharmaceutical requirements: microbial limits, at-rest and in-operation states, airflow controls, and a mandatory Contamination Control Strategy. Every GMP grade maps to an ISO class, but ISO alone does not satisfy GMP.
Which ISO class equals EU GMP Grade A?
EU-GMP Grade A corresponds to ISO 5 (≤3,520 particles ≥0.5 µm per m³), and this limit must be held in both the at-rest and in-operation states. Grade A is the cleanest zone, used for aseptic filling and open-product exposure, typically protected by unidirectional (laminar) airflow over the critical area.
What is the difference between at-rest and in-operation?
At rest means the cleanroom is complete and equipment is running, but no operators are present and no production is occurring. In operation means staff are working and the process is active. Particle limits are stricter to achieve in operation because people and processes generate contamination — Annex 1 requires compliance in both states.
What changed in the 2022 EU GMP Annex 1?
The 2022 Annex 1 (effective August 2023) made a Contamination Control Strategy (CCS) mandatory, placed Quality Risk Management at the centre, clarified ≥5.0 µm particle counting for Grades A/B, strongly encouraged isolators and RABS for aseptic processing, and reinforced PUPSIT and holistic environmental monitoring.
Do GCC regulators accept EU GMP and ISO 14644?
Yes. Saudi SFDA, UAE MOHAP, DHA and DoH, and Qatar MoPH all reference EU-GMP and ISO 14644 principles for sterile and non-sterile manufacturing. Designing to ISO 14644 and qualifying to EU-GMP Annex 1, documented under a CCS, gives the strongest position for GCC licensing and product registration.
Which grade do I need for sterile injectable manufacturing?
Sterile injectable fill-finish typically uses a Grade A critical zone (ISO 5, unidirectional airflow) within a Grade B background (ISO 5 at rest, ISO 7 in operation). Surrounding preparation and support areas are usually Grade C and D. The exact layout must follow your Contamination Control Strategy and product risk assessment.
Why does Gulf climate affect cleanroom grade compliance?
High heat, humidity, and airborne dust in the Gulf increase the load on HVAC, makeup-air, and pre-filtration systems. A cleanroom must be sized to hold its in-operation grade under local ambient conditions, so Gulf installations often require extra cooling, dehumidification, and filtration capacity compared with temperate-climate builds.
Cleanrooms supplied & installed across the GCC
Manufactured in Pakistan with GUSU (China) technology · shipped to Jebel Ali, Dammam & Hamad (CIF/DAP) · installation available across the Gulf.