Not All Boxes Are Equal: Investigation of Parameters Affecting Removal of PM2.5 Particles by Corsi-Rosenthal Box

ANTONIO BARATTA, Taewon Han, Gediminas Mainelis, Rutgers, The State University of New Jersey

     Abstract Number: 192
     Working Group: Reducing Aerosol Exposure with Control Technologies and Interventions

Abstract
Poor indoor air quality is an urgent and often underestimated public health challenge, especially in buildings where ventilation and air circulation are lacking, and infiltration of poor outdoor air is likely. The Corsi-Rosenthal (C-R) Box has gained widespread popularity as an affordable, do-it-yourself air cleaner designed to address these gaps in indoor air quality. Despite its rapid adoption, limited studies have evaluated how different operational variables affect the C-R Box’s efficiency. This study measured the Clean Air Delivery Rate (CADR) of C-R Boxes as a function of filter rating, its electret enhancement, location of measurement devices, and air mixing when challenged with sodium chloride (NaCl) or Arizona Road Dust (ARD) particles in a 3,024 ft³ (~86 m3) chamber. CADR focused on the removal of PM2.5 mass concentration. Results show that a C-R Box with four MERV-13 filters achieved CADR values of 358.56 ± 10.58 cubic feet per minute (cfm) at the maximum box fan speed, outperforming MERV-8 filters (209.93 ± 9.30 cfm) by 71% despite only a 41% increase in filter cost. MERV-13 filters with electret designation did not improve CADR compared to plain MERV-13 filters. When challenged with ARD particles, the C-R box achieved a CADR of 416.60 ± 8.31 cfm, compared to 358.56 ± 10.58 cfm with NaCl particles. We also observed that having the measurement device at 65 inches from the C-R Box increased the observed CADR by 8% compared to a 140-inch distance. Adding additional mixing fans helped improve the CADR in the chamber’s corners. For best results, C-R Boxes should use the highest MERV filters and fan speed and be placed close to the pollution source or area. Our systematic evaluation of the C-R Box’s performance will assist in optimizing its construction and deployment, thus improving its effectiveness for mitigating particulate pollution indoors.