Performance of Portable Air Cleaners in Reducing Particulate Matter in Real-World Application Scenarios

Frederic T. Lu, Robert Laumbach, Alicia Legard, Nirmala Thomas Myers, Kathleen Black, Pamela Ohman-Strickland, Shahnaz Alimokhtari-V, Adriana De Resende, Leonardo Calderón, GEDIMINAS MAINELIS, Howard Kipen, Rutgers, The State University of New Jersey

     Abstract Number: 210
     Working Group: Indoor Aerosols

Abstract
There is an increased interest in applying portable air cleaners (PACs) with HEPA filters to reduce indoor particulate matter (PM), including infectious viruses and bacteria. Meanwhile, the performance of PACs in naturalistic settings and in indoor spaces beyond the room containing the PAC (i.e., secondary rooms) is not well characterized. Here we report on the effectiveness of a PAC in reducing PM levels in both primary and secondary rooms and the impacts of central air systems on PAC performance.

We conducted a single-blinded, randomized, cross-over interventional study in the homes of 29 adults who tested positive for COVID-19. PACs with HEPA installed (“filter” state) were operated for 24 hr, while PACs operated with the filter removed (“sham” state, i.e., control) for 24 hr served as controls. The treatment order was randomized. The PM2.5 and PM10 concentrations were measured in real time in the room containing the PAC (i.e., primary room) and the room without a PAC (i.e., secondary room) using AirVisual Pro nodes (IQAir, Goldach, Switzerland). The effectiveness of the PACs was calculated as the percent reduction in mean PM concentrations during the filter state. Significance testing was by Wilcoxon signed rank test.

PAC effectiveness in reducing PM concentrations was 66.1% (n=26) for both PM2.5 and PM10 fractions in primary rooms and 13.9% and 25.0% (n=23), respectively, in secondary rooms. PAC-associated PM reductions were enhanced to approximately 80% in primary and 65% in secondary rooms when a central air handler was used.

Overall, we found that PACs substantially and significantly reduced PM2.5 and PM10 concentrations in primary rooms during 24 hr of operation. PM concentrations in secondary rooms were also reduced. Central air handlers seemed to potentiate the effectiveness of PACs in primary rooms and, to a lesser extent, in secondary rooms.