Reducing Aerosol Particle Concentration in Indoor Spaces with Mechanical Ventilation and Aircleaning: Evidences and Challenges

This study aims to experimentally investigate the efficiency of a mechanical ventilation (MV) system, with and without the presence of air cleaners (ACs), to reduce the aerosol particle concentration in indoor spaces. The measurements were performed in a case study room equipped with a MV system, an AC, and 16 artificial aerosol generators (AGs) to represent an intentional multifold of human respiratory aerosol generation. Five aerosol particle sizers (APS) were used to measure the concentration of the aerosol particles. Overall, five different scenarios (with and without ACs) were reproduced. The results show that when only AC was used 98% of the aerosol particles were removed within 30 min and the concentration peak was about half of that found for the scenario without AC and MV. When AC and MV with three different modes were used in combination, the concentration peak was found even less pronounced, with about 98% aerosol removed in about 20 min for 1st, 15 min for 2nd, and 13 min for 3rd ventilation settings.