Long-term field demonstration of acoustic vibration–assisted fine particulate matter reduction in large commercial buildings

This study presents a long-term field demonstration of an acoustic vibration–assisted system for reducing PM 2.5 in a large commercial building. Unlike laboratory-scale studies, the system was installed within the outdoor air intake section of an operating air handling unit and evaluated under real building conditions from March to May 2025 in Seoul, Republic of Korea, during a season characterized by elevated outdoor particulate pollution. A parallel chamber configuration was adopted to isolate acoustic effects under uncontrollable ventilation conditions. Two adjacent chambers were exposed to identical outdoor airflow, with one equipped with a 150 Hz acoustic module (∼80 dB) and the other serving as a reference. PM 2.5 concentrations were monitored at one-minute intervals, generating over 200,000 data points. The acoustically excited chamber consistently exhibited lower particulate concentrations, with statistically significant differences confirmed at the 95% confidence level. The reduction effect was more pronounced during periods of high outdoor pollution. Regression analysis further indicated reduced sensitivity of indoor PM 2.5 levels to external fluctuations under acoustic excitation. These results demonstrate that acoustic vibration can serve as an effective retrofit technology for controlling indoor PM 2.5 in commercial building ventilation systems.