The design and construction of GMP‑compliant cleanroom projects must first involve partitioning the entire facility according to process flows and production requirements. Such zoning should be rational and meticulous, minimizing personnel traffic and preventing cross‑contamination between material flows. Whether constructing a new cleanroom or retrofitting an existing one, the layout must meet the following criteria.

1. Deploy according to the process flow in a forward direction to minimize circuitous paths and back-and-forth movements in production. GMP cleanrooms are partitioned based on the manufacturing process, resulting in a compact and streamlined layout.

Principle of purification in GMP cleanrooms: Airflow‑based ultra‑efficient air treatment; in air‑conditioning systems, high‑efficiency air handling; fans for air supply; purified ductwork; air exhaust outlets; dust (and bacterial) removal within the cleanroom; ventilation with outdoor air and ultra‑efficient air treatment. Repeating this process achieves the desired level of air purification.

2. In GMP‑compliant cleanrooms, separate access points shall be provided for personnel and materials, and distinct entry/exit routes shall be established for raw materials and finished products to prevent cross‑contamination among incoming materials, intermediates, and semi‑finished products. Layout considerations should ensure that unrelated personnel or material flows do not traverse the production area. Cleaning equipment washing and storage rooms, as well as maintenance rooms, must not be located within the clean production area. The cleanliness level of laundry and drying rooms for clean workwear may generally be one grade lower than that of the production area; however, the cleanliness level of sterile garment finishing and sterilization rooms must match that of the production area.

3. The distance between the production area and the raw material and finished-product storage areas should be minimized to prevent contamination of pharmaceutical products during transport. For materials and waste that are prone to causing contamination, GMP‑compliant cleanrooms may, where necessary, be equipped with dedicated access points. The metrology room should be located near the raw-material storage area, and its cleanliness level should match that of the compounding room. Equipment for 100,000‑class and higher‑grade cleanrooms, as well as container‑cleaning rooms, may be situated in this area; however, cleaning rooms for 100‑class and 10,000‑class cleanrooms must be located outside the clean zone, with a cleanliness level one grade lower than that of the production area.

4. In GMP‑compliant cleanrooms, personnel and materials entering the clean facility must pass through dedicated cleanrooms and associated facilities; the design and configuration of these cleanrooms shall meet the cleanliness level requirements of the production area. Elevators used for transporting personnel and materials must be separate, and should, whenever possible, not be located in clean areas. If installation in a clean area is unavoidable, an airlock must be provided at the elevator entrance.

5. GMP‑compliant cleanrooms or areas with high air cleanliness should be located in zones with minimal personnel access and close to the HVAC room. Rooms or areas with differing cleanliness levels should be arranged from inside to outside, according to decreasing air cleanliness. GMP‑compliant cleanrooms or areas of the same cleanliness level should be grouped together. When rooms with different cleanliness levels are interconnected, measures to prevent cross‑contamination—such as air conditioning, air showers, buffer zones, or pass‑through windows—must be implemented.

6. The area of clean zones should be minimized; only essential process equipment and facilities should be installed in cleanrooms, and the number of personnel in GMP‑compliant cleanrooms should be kept to a minimum. In addition, the storage areas for raw materials, semi‑finished products, and finished products should be sized to match the production scale.