Influence of the Addition of Height-Adjustable Worktables on Airborne Particle Concentration in a Cleanroom According to ISO 14644-1

Cleanrooms are essential environments for the production of sterile pharmaceuticals and medical devices, where airflow stability and contamination control are critical. In this study, the influence of adjustable worktable height on air cleanliness was examined to determine whether height variation affects unidirectional airflow and particle concentration. Measurements were conducted under laboratory conditions in an ISO Class 6 cleanroom and in an industrial ISO Class 8 production line. Particle concentrations were recorded at table heights between 70 and 120 cm using a calibrated particle counter in accordance with ISO 14644-1 and ISO 21501-4. The measured data were evaluated against the classification limits defined in ISO 14644-1. Across all height levels, particle concentrations remained well below the permissible thresholds. In the ISO Class 6 cleanroom, measurement height showed a statistically significant effect on particles >5 μm, though this represented only a small contribution to the overall variance. In contrast, no significant height effect was observed in the ISO Class 8 cleanroom. Observed local differences were attributed to airflow distribution and the placement of air supply in-/outlets rather than table height. These results confirm that height-adjustable worktables can be implemented without affecting cleanroom classification, provided that uniform FFU placement and furniture positioning are considered during design and qualification.