Fig 1.
Fitted filtration efficiency for cloth (2), L1 (2) and L3 (2) certified medical masks, a non-certified Kegis 3D mask (purchased as a KN95 look-alike), KF94s (2), KN95s (3), and for respirators, N95 and CaN99.
N = 4. Bars present mean and standard deviation (SD) and whiskers showing 5 - 95 confidence values. Data were normal by Lillefor’s test. Letters above whiskers indicate statistical groupings according to Tukey’s post hoc comparisons. A shared letter for two mask types signifies no difference between those types; absence of a shared letter signifies a significant difference p < 0.05.
Fig 2.
Box and whisker plot showing the effect of minor modifications, or hacks, to a certified level 1 Polar Bear mask and to a certified level 3 Halyard mask.
10 participants, 1 replicate. Data were not normal by Lillefor’s test. Kruskal-Wallis with Conover-Inman post hoc comparisons. Boxes show interquartile range and whiskers minimum and maximum. Letters denote groups which are statistically similar and dissimilar: a shared letter for two mask types signifies no difference between those types; absence of a shared letter signifies a significant difference p < 0.05. Neoprene brace made using downloadable, public domain, template from Fix The Mask and recommended materials; silicone brace designed at McMaster University; FTM brace - proprietary Fix-The-Mask brace. L1 and L3 controls were retested on these participants as part of this panel; estimates differ slightly from those in Fig 1.
Fig 3.
Effects of overmasking with Essex masks on earloops and on overhead ties on fitted filtration efficiency.
The graph shows (left) the Essex mask on earloops (Earloop) and on ties (Ties) worn alone, followed by Essex-on-earloop with a second Essex-on-earloop as an overmask (Earloop-Earloop), and by Essex-on-earloop with an Essex-on-ties as an overmask (Earloop-Ties). The centre panel shows the level 1 certified Polar Bear mask worn alone (L1), with an Essex-on-earloop as an overmask (L1- Earloop), and with an Essex-on-ties as an overmask (L1-Ties). The right panel shows the level 3 certified Halyard mask worn alone (L3), with an Essex-on-earloop as an overmask (L3-Earloop), and with an Essex-on-ties as an overmask (L3-Ties). 6 participants, 3 replicates. Data were normal by Lillefor’s test. ANOVA with Tukey’s honestly significant difference for post hoc comparisons was used. Mean and median; boxes show one standard deviation (SD); whiskers show 95% confidence intervals. Letters denote groups which are statistically similar and dissimilar: a shared letter for two mask types signifies no difference between those types; absence of a shared letter signifies a difference. Earloop: Essex mask worn on elastic earloops. Ties: Essex mask worn on overhead cloth ties. L1 level 1; L3 level 3.
Fig 4.
Relationship between fitted filtration efficiency and glasses fog, and between fitted filtration efficiency and subjective leak.
Glasses fog and subjective leak were assessed before fitted filtration efficiency was measured. Top graphic fitted filtration efficiency against glasses fog score across data generated for each sub-study. Open circles are raw data, squares are means and whiskers are standard deviations for each score category. Dashed line is the linear regression fit: FFE = -1.78 ± 0.48 * Glasses Fog Score + 79.3 ± 1.7; R2 = 0.04; p < 0.001, df = 338. Bottom graphic presents data against leak score. Dashed line regression fit: FFE = -5.5 ± 0.6 * Leak Score + 88.5 ± 1.7; R2 = 0.22; p < 0.001, df = 338.
Table 1.
Summary demographic and anthropometric data on participants.