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Investigating Filtration Efficiencies of Non-standard Fabric Filters
SUMIT SANKHYAN, Hannah Teed, Teresa Barnes, Peter Ciesielski, Karen Heinselman, Sameer Patel, Marina Vance, University of Colorado Boulder
Abstract Number: 441
Working Group: The Role of Aerosol Science in the Understanding of the Spread and Control of COVID-19 and Other Infectious Diseases
Abstract
As a public health response to control the coronavirus disease (COVID-19) global pandemic, there is an urgent need to manufacture, test, and supply respirators and masks to healthcare providers, essential workers, and to the general population. This novel need is accompanied by a necessity to test the filtration efficiency and inhalation resistance of masks using non-standard materials as filters. It is essential to study the effects of factors such as mask fit, length of usage, and degradability due to repetitive use on filtration behavior of non-standard and “do it yourself” (DIY) masks in order to achieve optimum filtration performance and to put forth recommendations among the general public for mask usage.
In this study, overall and size-resolved filtration efficiencies were calculated for different mask prototypes and filter materials. A Scanning Mobility Particle Sizer (TSI) and an Aerodynamic Particle Sizer (TSI) were used to characterize the filtration efficiency of particles in the 12 nm- 10 µm size range. We tested various mask prototypes such as DIY cloth masks, surgical masks, N95 masks, BFE99 filters, and KN95 4-ply face masks. Preliminary results show that overall filtration efficiencies ranged from 30% to 100% for different mask prototypes. The inhalation resistance values for these masks ranged between 2-20 mm water column. Secondary investigations included studying the effect of degradability of the fabric filter material due to washing and drying on their filtration performance. We also investigated the potential of novel filter materials such as cellulose nanofibrils (CNF) coated fabric material as a substitute for DIY masks.