Fig 1.
Images of facemasks used in this study.
Each facemask is listed along with its in-text abbreviation (figure label) and an image of the facemask type.
Fig 2.
Schematic of experimental set-up.
A. Schematic of the enclosed box experimental setup showing the (a) face model, (b) idealized airway replica, (c) throat adapter, (d) PARI LC Sprint Nebulizer, (e) Vios compressor, (f) particle counter, and (g) facemask. Additionally, the locations where particle counts were measured are represented by red dots; specifically, the Front, Side, and Top. B. Schematic of the open bench experimental setup, showing the face model with a facemask, connected to the same nebulizer (not shown), and the distances at which particles were measured with the particle counter: one foot, three feet, and six feet (0.3 m, 0.9 m, and 1.8 m), in both the Front and Side positions. C. Representative example of the data collected at each sample, with particle size bins for 0.3, 0.5, 1, 3, 5, and 10 μm particles grouped together in increasing order such that each grouping represents a facemask and position, such as No Mask and With Mask for one foot (0.3 m) from the model.
Fig 3.
Background-corrected particle counts comparing facemask treatments within the enclosed box.
Measurements shown in each row for the six particle size bins are shaded and grouped by facemask type, including No Mask, Sewn, SewnF, SewnPC, Surgical, N95L and N95T. Axes are scaled to each respective range, and gray bullet points at the baseline indicate negative corrected counts. Error bars indicate the sample standard deviation for particle counts in each of the respective particle size bins from three independent measurements. A 2-factor MANOVA and subsequent 2-factor ANOVAs were performed in addition to Tukey's Honest Significant Difference tests; p-values, relevant parameters, and analysis are shown as interactive maps and graphs included in S2 File.
Fig 4.
Background-corrected particle counts comparing facemask treatments in the open bench environment.
Each plot shows background-corrected particle counts for each of the facemasks, which are ordered from least to greatest pressure drop, at distances of one foot, three feet, and six feet (0.3 m, 0.9 m, and 1.8 m) away from the face model. The Front position is shown for each distance. Binning by particle diameter for each facemask is grouped together by row, in order of size from 0.3–10 μm, as described in Fig 2. Axes are scaled to each respective range, and gray bullet points at the baseline indicate negative corrected counts. Error bars indicate standard deviation for particle counts in each of the respective particle size bins from three independent measurements. A 3-factor MANOVA and subsequent 3-factor ANOVAs were performed in addition to Tukey's Honest Significant Difference tests p-values, relevant parameters, and analysis are shown as interactive maps, and contour plots and graphs of data from one foot, three feet, and six feet (0.3 m, 0.9 m, and 1.8 m) in the Front and Side positions are included in S3 File.
Fig 5.
Background-corrected particle counts comparing Front and vulnerable positions for each facemask at a one-foot (0.3 m) distance in the open bench environment.
Measurements shown are grouped by particle size bin and colored by measurement position. Row 1 includes particle counts for the Front position of each facemask. Row 2 includes vulnerable positions deemed significant during experimental observation. Vulnerable positions include: Side (Surgical mask), Bottom (N95L), and Top (sewn masks, N95T). Gray bullet points at the baseline indicate negative background-corrected counts. Error bars indicate the sample standard deviation for particle counts in each of the respective particle size bins from three independent measurements. For statistical analyses, refer to the open bench analysis described in Fig 4.
Fig 6.
Background-corrected cumulative size distributions comparing distributions at vulnerable positions for each facemask in the enclosed box environment.
Vulnerable positions include: Side (Surgical mask), Front (No Mask, N95L), and Top (sewn masks, N95T). Diameter (D) obtained from upper bin size and reported in μm. Error bars represent standard deviation for particle counts in each of the respective particle size bins from three independent measurements.
Table 1.
Count Median Diameters (CMD) of particles collected at vulnerable locations between facemask treatments in the enclosed box environment.
Fig 7.
Background-corrected particle counts comparing facemask treatments within the enclosed box.
Measurements shown for the six particle size bins are shaded and grouped by the measurement position (Front—Green, Left; Side—Yellow, Middle; Top—Blue, Right). Row 1 includes No Mask, Sewn, SewnF, SewnPC. Row 2 includes more advanced and commercially available facemask treatments (Surgical, N95L, and N95T masks). Gray bullet points at the baseline indicate negative corrected counts. Error bars indicate the sample standard deviation for particle counts in each of the respective particle size bins from three independent measurements. A 2-factor MANOVA and subsequent 2-factor ANOVAs were performed in addition to Tukey's Honest Significant Difference tests; p-values, relevant parameters, and analysis are shown as interactive maps and graphs included in S2 File.
Table 2.
Pressure drop across facemask materials.
Table 3.
Overview of limitations and benefits of this study.