| 1. Cooper DW, Hinds WC, Price JM, Weker R, Yee HS. Common materials for emergency respiratory protection: Leakage tests with a manikin. Am Ind Hyg Assoc J. 1983;44(10):720–6..(7)
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Laboratory |
Tests conducted on a manikin connected to a breathing simulator to determine the fraction of a 2-micron diameter aerosol and the efficacy of different kinds of materials. Cotton/polyester shirt material, cotton handkerchief material, toweling, a surgical mask, and a disposable face mask were used. |
At a breathing rate of 37 liters per minute, mean leakages for the materials ranged from 0% to 63%, and mean penetrations of particles ranged from 0.6% to 39%. The use of nylon to hold the handkerchief material or the disposable face mask to the face was found to be very effective in preventing leakage. |
The use of nylon hosiery material (“pantyhose”) to hold the handkerchief material or the disposable face mask to the face was considered to be very effective in preventing leakage. Such a combination could be expected to reduce leakage around the handkerchief to about 10% or less in practice, and around the mask to less than 1%. |
| 2. van der Sande M, Teunis P, Sabel R. Professional and home-made face masks reduce exposure to respiratory infections among the general population. PLoS One. 2008;3(7):e2618.(8)
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Laboratory |
Three different types of masks were tested, two of them professional masks and a homemade mask made of teacloths. Individuals were instructed to perform specific tasks while particle concentration was measured on both sides of the mask. |
The study points to the superiority of FFP2 masks, followed by surgical masks, and lower efficacy of homemade masks; it also shows the time of use and Humidity as significant factors for decreased efficacy. |
All masks afforded protection against transmission, thus reducing exposure during all types of activities in both children and adults. |
| 3. Rengasamy S, Eimer B, Shaffer RE. Simple respiratory protection—evaluation of the filtration performance of cloth masks and common fabric materials against 20–1000 nm size particles. Annals of occupational hygiene. 2010;54(7):789-98.(9)
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Laboratory |
The study assesses different types of fabric materials including sweatshirts, T-shirts, towels, scarves, and compares them to the N95 mask for the capacity for filtering particles at different velocities. |
Towels and scarves: 60–66% and 73–89% for both velocities. Sweatshirts: 30–61% for 20 nm particles, increasing to 80–93% for 1000 nm particles. T-shirt: 56–79% for 20 nm particles and 89–97% for 1000 nm particles. Towels and scarves: 9–74% for 20 nm particles (9). |
Results show that sweatshirt and towel masks may provide lesser penetration levels when compared to other kinds of fabric materials; all analyses showed inferior results to the filtering capacity of an N95 mask. |
| 4. Brienen NC, Timen A, Wallinga J, van Steenbergen JE, Teunis PF. The effect of mask use on the spread of influenza during a pandemic. Risk Anal. 2010;30(8):1210-8.(5)
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Review |
Reflection on the need for implementing pharmaceutical (vaccination and antiviral drugs) and non-pharmaceutical countermeasures for pandemic preparedness purposes. |
Masks have traditionally been used for centuries. Retrospective case-control studies showed that mask use by the general population may have afforded significant protection against SARS. |
Face mask use at a population level can delay an influenza pandemic and decrease the infection attack rate, thus reducing transmission sufficiently to contain a pandemic. The effect on the final size of the epidemic depends on features of virus transmission, mask efficiency, and coverage of mask use in the population. |
| 5. Davies A, Thompson K, Giri K, Kafatos G, Walker J, Bennet A.T Testing the efficacy of homemade masks: would they protect in an influenza pandemic? Disaster Med Public Health Prep. 2013; 7(4):413-8.(10)
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Laboratory |
Twenty-one healthy volunteers were requested to make homemade face masks using 100% cotton fabric. Microorganisms were isolated using various air sampling techniques, and the use of homemade cotton face masks was compared to the use of surgical masks, or the use of no masks. The capacity to filter and block microorganisms was evaluated. |
The study’s main result was the capacity shown by different types of fabric to block microorganisms. The study shows the use of homemade masks is adequate for the population, but they should not be worn by healthcare providers. |
All three different types of fabric were able to block microorganisms; the surgical mask performed up to three times better. The use of homemade masks is adequate for the population, but they should not be worn by healthcare providers. |
| 6. Shakya KM, Noyes A, Kallin R, Peltier RE. Evaluating the efficacy of cloth facemasks in reducing particulate matter exposure. J Expo Sci Environ Epidemiol. 2017;27(3):352-7.(11)
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Laboratory |
Comparative study on the retention of particles by different types of masks. The study assessed three types of cloth masks and one type of surgical mask. Five monodispersed aerosol sphere sizes and diluted whole diesel exhaust were used in testing. |
Among the three cloth mask types, the cloth mask with an exhaust valve performed best. An N95 mask was used as a control and compared to the cloth face mask results; results suggest that cloth face masks are only marginally beneficial in protecting individuals from particles<2.5 μm. |
N95 masks performed better in particle removal, despite other cloth face masks also showing marginal percentiles of particle removal. Compared with cloth masks, disposable surgical masks are more effective in reducing particulate exposure. |
| 7. Konda A, Prakash A, Moss G, Schmoldt, Gregory D. Grant, Guha M. Aerosol filtration efficiency of common fabrics used in respiratory cloth masks. ACS Nano. 2020 Apr 24:acsnano.0c03252.(12)
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Cross-sectional study |
Tests different kinds of fabrics for face makes; 15 different fabrics. |
Three variations were measured: one layer of 600 TPI combined with two layers of silk, two layers of chiffon, and one layer of flannel. The results are compared with the performance of a standard N95 mask. |
Two layers of 600 TPI cotton is clearly superior, showing >65% efficiency for >300 nm and >90% efficiency for >300 nm. The quilt also provided excellent filtration across the range of particle sizes (>80% for <300 nm and >90% for >300 nm). The performance of a four-layer silk composite offers >80% filtration efficiency across the entire range, from 10 nm to 6 μm. |
