Table 1.
Consumer fabric categories, purchase source and intended fabric application of items characterized.
Fig 1.
Flow chart of study design used for material and mask characterizations, model calibration and selection of optimum cotton materials for use in constructing 2-ply cotton masks.
Fig 2.
Electron microscopy images of selected fabrics.
A) WP004 Bandana with plain weave, B) WP045 High Quality Quilting Fabric with plain weave, C) WP028 tea towel with complex weave; D) WP036 Bed Sheet with complex weave, E) Outer Layer L1 medical mask nonwoven, F) Middle Layer of L1 medical mask nonwoven. Microscope images for all 52 fabrics are provided in S2 File.
Table 2.
Selected mean ± standard error (%CV) of fabric characteristics across fabric consumer categories.
Fig 3.
Biplot of principle component scores and fabric measurement vectors.
PA = pore area; PD = pore diameter, %P = % pores in fabric, HTS = horizontal thread size, FW = fabric weight, VTS = vertical thread size, PS = pore shape, #HT = number horizontal threads, #VT = number of vertical threads, TD = thread density.
Fig 4.
Correlation between mask filtration efficiency and mean fabric pore diameter (Graphic A) and fabric weight (Graphic B) and goodness of fit tests comparing observed against predicted mask performance from Eq 2 (Graphic C) and for material differential pressure from Eq 3 (Graphic D).
Fig 5.
Model estimated mask performance across consumer fabric categories (Graphic A). Box and whisker plots present the median (box center horizonal line), mean (▪), standard deviation (upper and lower box edges) and range (whiskers) of model predicted mask filtration performance across each fabric category. Symbols (○) present mean ± standard error of measured mask fitted filtration efficiency determined for each tested fabric masks from each category. Horizontal dashed lines present the range of measured mask filtration efficiencies for the L1 medical mask. Graphic B. Model estimated breathability performance across consumer categories. Graphic legend descriptors similar to those described for graphic A. Dashed horizontal line is the Level 1 Medical Mask ASTM guideline value, dotted line is the Level 3 Medical Mask ASTM guideline value.
Fig 6.
Fitted filtration efficiencies with and without a mask fitter.
Column descriptors T1 and T2 refer to Tester #1 and Tester #2. L1 control refers to the L1 medical mask donned with ear loops, L1 + Fitter is the medical mask worn with a mask fitter, WP045 is a high quality quilting cotton mask donned with fabric ties and WP045 + Fitter is the same mask worn with a mask fitter. Bars with different letters are significantly different from one another (p<0.05; Tukey’s pairwise comparisons test).