According to the article, the cloth mask in Figure 1A (Easy Masks LLC) was a "2-Layer woven nylon mask" composed of "54% recycled nylon, 43% nylon, 3% spandex". However, I would appreciate clarification of the following. I enjoyed reading this important article. We used the term "woven" in a similar fashion, which is incorrect.Īs previously stated, we regret the error and are working with the journal to correct references to “woven” throughout the article. 1D) states on their website, “Our single layer masks are made with tightly woven Nightingale™ 200 needle material for the perfect combination of lightweight comfort and breathability.” The manufacturers of both masks appear to use “woven” as a generic descriptor for mask construction. 1A) states on their website, “masks are woven” and “.the specific weave used in the mask body has extremely high surface area for good filtration.” The manufacturer of the single-layer polyester/nylon mask (Fig. However, the manufacturer of the 2-layer nylon mask (Fig. The masks pictured in Figures 1A and 1D are indeed knitted and not woven. While addressing the original comment we carefully inspected the construction of each mask tested and compared our findings with data provided by the manufacturers. We appreciate the additional comment from Kat Preston regarding the construction of masks pictured in Figures 1A and 1D in our article. ![]() Based on the mechanisms of particle deposition that govern filtration (i.e., diffusion, impaction, interception, and sedimentation), protection against aerosols of 0.05-μm particles would also confer similar or better protection against much larger aerosols or droplets, which, as you correctly state, are currently believed to be the predominant source for COVID-19 transmission. This generator is commonly used to supplement ambient particle concentrations to allow for accurate fit testing of N95 respirators. In regards to the aerosol composition of our test atmosphere, the exposure chamber was supplemented with NaCl particles using a TSI 8026 Particle Generator specifically made for respirator fit testing. We regret the error, and have requested that the article be corrected. This is important because, as you and the previous commenter have pointed out, cotton knit fabric is reported to be less efficient in filtering aerosols than cotton woven fabrics. It is, in fact, made with a knitted fabric. As stated in the previous comment, we erroneously referred to the material used in the 3-layer cotton mask tested in this study as “woven”. We appreciate your comments and clarifications. This approach would provide an understanding of how the mask perform related to droplets and aerosols, of interest. It would seem more relevant to test using larger particles of size 5.0 μm, 1.0 μm, and 0.5 μm. Testing the filtration efficiency of a cloth mask to stop a 0.05 μm particle may lead to false conclusions. Using a particle or smaller size is surprising, when researchers consistently talk about the airborne COVID-19 virus riding on droplets (5 μm) and aerosols (1 μm). The test methodology using an 0.05 μm diameter particle is smaller than the size of the COVID-19 virus which is approximately 0.1 μm. I also question the decision to use 0.05 μm particles to test the efficacy of cloth, non-medical masks. Knit fabrics are not woven.Īs experts recommend tightly woven cotton fabric for masks, hence, it is hard to understand why the researchers this particular mask. Other studies have shown that cotton "knit" fabrics are less effective than cotton woven fabrics for masks. Hanes is known for their cotton "knit" masks. ![]() Unfortunately, the mask tested is a Hanes cotton "knit" fabric mask. ![]() The researchers refer to a 3-layer cotton woven fabric mask. Shared Decision Making and Communication.Scientific Discovery and the Future of Medicine.Health Care Economics, Insurance, Payment.Clinical Implications of Basic Neuroscience.Challenges in Clinical Electrocardiography.
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