The investigation was a result of a dissolution out-of-trend (OOT) identified. The root cause analysis attributed the OOT to a chilled water supply system. Supporting evidence revealed that the dew point temperature in the OOT batch was notably higher compared to the PPQ and other batches. The elevated inlet air moisture impacted the semipermeable cellulose acetate polymer coating, altering the mass transfer dynamics and surface morphology, leading to increased surface porosity and delayed dissolution rates. The findings were corroborated by supporting evidence. The investigation underscores the critical role of controlling inlet air moisture during the polymer coating process to ensure consistent product quality.