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In the pharmaceutical and biotechnology industries, cleanrooms are key facilities to ensure product quality and safety. One of the core of aseptic technology is to control the laminar air flow speed in the cleanroom to maintain a sterile environment. This article will explore the scientific basis, regulatory requirements and how to combine Class A laminar air flow speed with cleanroom design.

Cleanrooms are designed to control particulate and microbial contamination to protect sensitive manufacturing processes and products. In these controlled environments, air flow is one of the key factors because it directly affects the particle distribution in the air and the removal efficiency of pollutants.

Both EU GMP Annex 1 and NMPA GMP mention that the unidirectional flow system should provide a wind speed of 0.36m/s to 0.54m/s in its working area, but this is only a guide value. This means that in actual operation, as long as it can be scientifically justified, the wind speed can be adjusted according to the specific situation.

EU GMP Annex1:
4.30...Unidirectional airflow systems should provide a homogeneous air speed in a range of 0.36 – 0.54 m/s (guidance value) at the working position, unless otherwise scientifically justified in the CCS. Airflow visualization studies should correlate with the air speed measurement.

NMPA GMP:

Appendix Sterile Drugs Article 9: The unidirectional flow system must deliver air evenly in its working area, with a wind speed of 0.36-0.54m/s (guideline value). There should be data to prove the state of unidirectional flow and be verified.

The standard of 0.45m/s±20% actually comes from the US FS 209 standard, which is based on experience and does not consider energy consumption, but more on the noise of the fan. Studies have shown that higher cleanliness can be achieved at lower air speeds because lower wind speeds reduce turbulence around objects in the flow path.

When designing a clean room, it is necessary to consider the effect of wind speed on cleanliness. Wind speed not only affects the removal efficiency of particles, but also affects the comfort and energy consumption of operators. When designing, these factors need to be balanced to achieve the best sterile environment.

The regulatory standards for unidirectional airflow velocity in clean rooms vary in terms of measurement location and the weight of a specific velocity. According to the guidance of the US FDA, it is required to measure the airflow velocity at a distance of 6 inches below the filter surface. ISO 14644 requires that the airflow velocity be measured at approximately 150mm to 300mm from the filter surface. However, according to EU (and WHO) GMP, the airflow is measured at the working height, which is defined by the user.

Flow velocity and airflow are essentially for the purpose of removing contamination and preventing contamination. The optimal flow velocity can be determined through visualization studies as well as particle monitoring. The purpose of the visualization study is to confirm the smoothness, flow pattern and other spatial and temporal characteristics of the airflow in the device. To this end, the airflow is checked through airflow visualization mapping, by generating smoke and studying the behavior of the smoke, which is then captured with a camera.

Therefore, the Class A laminar air velocity of 0.36m/s to 0.54m/s is not a standard that must be strictly followed, but a guide value. In actual application, the wind speed can be adjusted according to the specific situation. The key is to be able to justify it through scientific methods.

When designing a clean room, it is necessary to comprehensively consider the impact of wind speed on particle control, operator comfort and energy consumption to achieve an optimal sterile environment. Through airflow visualization and particle monitoring, the optimal air speed can be determined to ensure the efficient operation of the clean room, thereby protecting the quality and safety of pharmaceutical products.