Cleaning the Indoor Air with Low-Cost DIY Air Cleaners
Nirmala Thomas Myers, Taewon Han, Kevin Dillon, GEDIMINAS MAINELIS,
Rutgers, The State University of New Jersey Abstract Number: 165
Working Group: Indoor Aerosols
AbstractThe do-it-yourself (DIY) air cleaners offer an easy and cost-effective way to remove particles, bioaerosols, and their agglomerates from indoor air. Our study evaluated the particle removal efficiency and clean air delivery rate (CADR) of DIY air cleaners with a 20 x 20-inch box fan and commercially-available filters (Filterbuy Inc., Talladega, AL, USA) of 1-inch, 2-inch, and 4-inch thickness with MERV rating ranging from 6 to 14. The selection criteria were total costs of < $50 for a single-filter DIY air cleaner and < $100 for a multi-filter DIY air cleaner. The filtration efficiency testing was performed with 10% NaCl liquid suspension aerosolized at 10 L/min (19 psi) using a 6-jet Collison nebulizer (CH Technologies, Westwood, NJ, USA), yielding a 10 nm – 10 μm particle size range and 150-200 µg/m
3 mass concentration. Experiments were performed in a classroom modified to be a large test chamber (85 m
3). The particle mass and number concentrations, including size distribution, of the produced aerosol were measured using a DRX (TSI Inc., Shoreview, MN, USA) and the Mini Wide-Range Aerosol Spectrometer (Grimm Inc., Aerosol Technik GmbH & Co. KG, Ainring, Germany). The box fan’s sound levels and heating were also monitored. The results show that DIY air cleaners can achieve CADR of 200 cfm or higher with a proper filter selection. The CADR values were similar to those of commercial HEPA air cleaners costing up to 10x higher. The CADR values were the highest for MERV 13 filters compared to MERV 8 and MERV 11 filters. In addition, MERV 13 4-inch single-filter models performed superior to the 2-inch and 1-inch single-filter models with the same MERV rating. This study demonstrates the utility of low-cost DIY filters in improving indoor air quality. The results will help DIY enthusiasts to pick the best fan-filter combination to mitigate exposures to indoor particles, including infectious aerosols such as SARS-CoV-2 and other viruses.