Furuhashi, 19782424. Furuhashi M. A study on the microbial filtration efficiency of surgical face masks—with special reference to the non-woven fabric mask. Bull Tokyo Med Dent Univ. 1978 Mar;25(1):7-15. (Japan) |
100% Cotton Masks: • Bleached cotton fabric (thread, 40x46/2.5cm), • Bleached cotton fabric (thread, 46x50/2.5cm), • Twill weave (thread, NA), • Calico (thread, 80x80/ 2.5cm). Layers: NA |
Triple layer surgical mask with thin layer of fiberglass filter (quality standard NA): • Hopes®, • Medispo®
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Bacterial Aerosol with Staphylococcus aureus: (cocci 1μm in diameter). Air flow: 28.3L/min. Analysis: Filtration Efficiency (%) and Airflow resistance (ΔP). One sample of each type of mask was evaluated at least 5 times. |
“It is useful both in preventing hospital infection and in general clinical practice. The bacterial filtration efficiency of the conventional cotton cloth masks is not only lower but varible over a wide range of 43.1-93.6%.” |
Van der Sande et al., 20082828. Sande M, Teunis P, Sabel R. Professional and home-made face masks reduce exposure to respiratory infections among the general population. PLoS One. 2008 Jul;3(7):e2618. https://doi.org/10.1371/journal.pone.0002618 https://doi.org/10.1371/journal.pone.000...
(The Netherlands) |
100% Cotton Homemade masks: (made of TD Cerise Multi® teacloths, Blokker). Layers: NA |
• Three layer surgical mask (1818 Tie-On®, EN14683:2005). • FFP-2 mask 1872VH (3M) |
• Experiment 1: 39 Volunteers' performance in increased respiratory sequence (10-15 min). 28 adults and 11 children used the 3 masks (SM, FFP-2 and Homemade CM) during 1.5min. PS: 0.02-1μm. Air flow: Variable. |
“Any type of general mask use is likely to decrease viral exposure and infection risk on a population level, in spite of imperfect fit and imperfect adherence, personal respirators providing most protection. Masks worn by patients may not offer as great a degree of protection against aerossol transmission.” |
• Experiment 2: 22 Volunteers' performance in increased respiratory sequence (3 hours). All adults, divided in 3 masks (3 hours). PS: 0.02-1μm. Air flow: Variable. |
• Experiment 3: Simulated infectious patient expiration. PS: 0.02-1μm. Air flow: 30, 50 and 80L/min. |
Analysis: Protection Factor. One sample of each type of mask was evaluated twice at each air flow. |
Rengasamy et al. 20102525. 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. Ann Occup Hyg. 2010 Oct;54(7):789-98. https://doi.org/10.1093/annhyg/meq044 https://doi.org/10.1093/annhyg/meq044...
. (United States) |
• Sweatshirts (Norma kamalic tunic; Hanes; Faded Glory), • Tshirts (Dickies; Hanes; Faded Glory), • Towels (Pem America; Pinzon; Aquis), • Scarves 100% cotton (Today´s Gentleman; Walmart; Seed Supply). Commercial CM: • Respro Bandit mask (100% cotton scarf with internal filter in breathing área), • Breathe Healthy Cloth Mask (nylon and polyester with Aegis Microbe Shield® anti-microbial treatment;%: NA), •Breathe Healthy Fleece Mask (fleece) |
• N95 respirator filter media. |
NaCl Aerosol penetration test with particles of diameter varying from 0.075 ± 0.02μm (polydisperse) and < 0.4μm - 1μm (monodisperse). Air flow: 33 and 99L/min. Analysis: Penetration level (%). |
“Results obtained in the study show that common fabric materials may provide marginal protection against nanoparticles including those in the size ranges of vírus containing particles in exhaled breath.” |
One sample of each type of mask was evaluated twice at each air flow. Three samples from each fabric materials were tested to polydisperse particles and another three samples to monodisperse. |
Davies et al. 20132323. Davies A, Thompson KA, Giri K, Kafatos G, Walker J, Bennett A. Testing the efficacy of homemade masks: would they protect in an influenza pandemic? Disaster Med Public Health Prep. 2013 Aug;7(4):413-8. https://doi.org/10.1017/dmp.2013.43 https://doi.org/10.1017/dmp.2013.43...
. (United Kingdom) |
Common household materials: 100% cotton T-shirt, Scarf, Tea towel, Pillowcase, Antimicrobial Pillowcase, Vacuum cleaner bag, Cotton mix, Linen and Silk. Layers: 1 (all); 2 (100% cotton t-shirt, tea towel and pillowcase). |
• Four layers surgical mask (Molnlycke Health Care Barrier face mask 4239, EN14683) |
• Experiment 1: Bacillus atrophaeus (0.95-1.25μm) and Bacteriophage MS2 (0.023μm) aerosols. Air flow: 30L/min. One sample of each material was evaluated nine times. Analysis: Filtration Efficiency (%) and Median (IQR) of Pressure drop across fabric. |
“Our findings suggest that a homemade mask should only be considered as a last resort to prevent droplet transmission from infected individuals, but it would be better than no protection.” |
• Experiment 2: Aerosols and droplets from 21 healthy volunteers wearing protective clothing (Tyvek suits) coughed twice into the box. The air inside was sampled for 5 minutes. Analysis: Median, IQR of Colony-Forming Units. |
Jung et al. 20142929. Jung H, Kim J, Lee S, Lee J, Kim J, Tsai P, et al. Comparison of filtration efficiency and pressure drop in anti-yellow sandmasks, quarantine masks, medical masks, general masks, and handkerchiefs. Aerosol Air Qual Res. 2014;14(3):991-1002. https://doi.org/10.4209/aaqr.2013.06.0201 https://doi.org/10.4209/aaqr.2013.06.020...
. (South Korea) |
Handkerchiefs from 1 to 4 layers (Cotton, Gauze and Towel) |
• Surgical and dental masks (brand/layers/ quality standard NA) |
NaCl Aerosol or parafin oil with PS from 0.075 ± 0.02μm. Air flow: 85L/min. Analysis: Penetration level (%) and Pressure Drop (mmH2O). Initial penetration using KFDA and NIOSH protocol by mask types. One sample of each type of material was evaluated three times. |
“All tested quarantine masks satisfied the KFDA criterion of 6%. Six-ninths and four-sevenths of the anti-yellow sand masks for adults and children satisfied the criterion of 20%, respectively. Medical masks, and handkerchiefs were found to provide little protection against respiratory aerossols.” |
• Quarentine masks: N95 respirator and similars. |
Maclntyre et al. 20151313. MacIntyre CR, Seale H, Dung TC, Hien NT, Nga PT, Chughtai AA, et al. A cluster randomised trial of cloth masks compared with medical masks in healthcare workers. BMJ Open. 2015 Apr;5(4):e006577. https://doi.org/10.1136/bmjopen-2014-006577 https://doi.org/10.1136/bmjopen-2014-006...
. (Vietnam) |
Cotton cloth masks (CM) with 2 layers manufacturated in Vietnam. |
• Three layers surgical masks (brand/quality standard NA). |
• Experiment 1: Prevention of respiratory infections with 1607 Health Care Workers randomized to 3 groups: SM, CM and standard practice. Analysis: Compliance (more than 70% of working hours) + Intention to treat analysis: 01-Clinical respiratory illness (CRI), defined as two or more respiratory symptoms or one respiratory symptom and a systemic symptom; 02-influenza-like illness (ILI), defined as fever ≥38 °C plus one respiratory symptom and 03-laboratory-confirmed viral respiratory infection. |
“This study is the first RCT of CM, and the results caution against the use of CM. This is an important finding to inform occupational health and safety. Moisture retention, reuse of cloth masks and poor filtration may result in increased risk of infection. Further research is needed to inform the widespread use of cloth masks globally. However, as a precautionary measure, CM should not be recommended for hospital healthcare workers, particularly in high-risk situations, and guidelines need to be updated.” |
• FFP-2 masks |
• Experiment 2: NaCl Aerosol. PS: 0.02 to 2μm equivalent diameter and a mass median particle diameter of 0.3 to 0.6μm. Air flow: 95L/min. Analysis: Filtration efficiency (%) |
• FFP-3 masks |
Sample and number of tests for each type of mask: NA |
• N95 respirator |
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Shakya et al. 20162222. 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 May;27(3):352-7. https://doi.org/10.1038/jes.2016.42 https://doi.org/10.1038/jes.2016.42...
. (United States) |
• 2 commercial cloth masks (model/brand/layers NA) • 1 Commercial cloth mask with exahalation valve (model/brand/layers NA) |
• Surgical masks (brand/quality: NA). |
Polystyrene latex and Diesel PS ranging from 0.03 to 2.5μm. Air flow: 8 and 19L/min. Analysis: Filtration efficiency (%). Experiments were repeated three times for each mask type against PSL particles, and two times against diesel-generated particles. |
“Standard N95 mask performance was used as a control to compare the results with CM, and our results suggest that CM are only marginally beneficial in protecting individuals from particles <2.5μm. Compared with CM, disposable SM are more effective in reducing particulate exposure.” |
• N95 respirator |
• N95 respirator with exhalation valve |
Cherrie et al. 20182626. Cherrie JW, Apsley A, Cowie H, Steinle S, Mueller W, Lin C, et al. Effectiveness of face masks used to protect Beijing residents against particulate air pollution. Occup Environ Med. 2018 Jun;75(6):446-52. https://doi.org/10.1136/oemed-2017-104765 https://doi.org/10.1136/oemed-2017-10476...
. (United Kingdom) |
Three layers commercial cloth masks with PM2,5 filter: • Green shield, • Yi Jie PM2.5 |
• FFP-2 masks (3M8210; 3M9001; 3M9322), • N95 respirator (3M9501; 3M9502), • Yimeijian mask |
High Particulate Matter (PM2,5) and Black Carbon (BC) ranging from 0.1 to 2.5μm. Air flow: 40 and 80L/min. Analysis: Penetration level (%). One sample of each type of mask was evaluated for 30 min under flow rates. |
“Many commercially available face masks may not provide adequate protection, primarily due to poor facial fit. Our results indicate that further attention should be given to mask design and providing evidence based guidance to consumers.” |
• Gucheng |
Liu et al. 20192727. Liu Z, Yu D, Ge Y, Wang L, Zhang J, Li H, et al. Understanding the factors involved in determining the bioburdens of surgical masks. Ann Transl Med. 2019 Dec;7(23):754. https://doi.org/10.21037/atm.2019.11.91 https://doi.org/10.21037/atm.2019.11.91...
. (China) |
Cloth mask– Mask C (model/brand/layers NA) |
• Three layers surgical mask with one filter screen – Mask A (brand/layers/quality: NA). |
NaCl Aerosol |
“Mask B possessed the highest filtering efficiency and lowest airflow resistance, which the best in blocking airborne particles and provided the best air permeability, enabling the surgeons to breathe freely. On the contrary, mask C possessed the lowest filtering efficiency and highest airflow resistance, meaning it was the worst in blocking airborne particles and in air permeability, causing breathing difficulties in surgeons. Mask C is not recommended to be used, especially considering that surgeons do not wash the cloth masks daily. Unnecessary talking during operation is not recommended, and washing the face before surgery is not strictly necessary.” |
• Four layers surgical mask with two filters screen – Mask B (brand/layers/quality: NA). |
Particles dimension: (0.075μm) |
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Air flow: 85L/min |
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Analysis: Filtration Efficiency (%) and Airflow resistance (ΔP). |
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Sample and number of tests for each type of mask: NA |
Bae et al. 20203030. Bae S, Kim MC, Kim JY, Cha HH, Lim JS, Jung J, et al. Effectiveness of surgical and cotton masks in blocking SARS-CoV-2: a controlled comparison in 4 patients. Ann Intern Med. 2020 Jul;173(1):W22-3. https://doi.org/10.7326/M20-1342 https://doi.org/10.7326/M20-1342...
(South Korea) |
Reusable 100% cotton masks (160 mm × 135 mm, 2 layers, individually packaged in plastic; Seoulsa) |
Surgical masks (180 mm × 90 mm, 3 layers (KM Dental Mask, KM Healthcare Corp, GB2626-2006). |
4 isolated patients with COVID-19 were instructed to cough 5 times each while wearing the sequence of masks: no mask, surgical mask, cotton mask, and again with no mask. Mask surfaces were swabbed with aseptic Dacron swabs in the sequence: outer surface of surgical mask, inner surface of surgical mask, outer surface of cotton mask, and inner surface of cotton mask. |
“Both surgical and cotton masks seem to be ineffective in preventing the dissemination of SARS–CoV-2 from the coughs of patients with COVID-19 to the environment and external mask surface.” |
Konda et al. 20203131. Konda A, Prakash A, Moss G, Schmoldt M, Grant G, Guha S. Aerosol filtration efficiency of common fabrics used in respiratory cloth masks. ACS Nano. 2020;14(5):6339-47. (United States) |
10 different types of fabrics w/ 1 or 2 layers: 1. Cotton (80 and 600 threads per inch), 2. Quilter´s Cotton, 3. Flannel (65% cotton and 35% polyester), 4.Synthetic silk (100% polyester), 5. natural silk, 6.Spandex (52% nylon, 39% polyester, and 9% Spandex), 7. Satin (97% polyester and 3% Spandex), 8.Chiffon (90% polyester and 10% Spandex), 9.Polyester, 10. Polyester+cotton |
• Surgical mask (brand/layers/quality standard NA). |
Polydisperse NaCl Aerosol |
“Although the filtration efficiencies for various fabrics when a single layer was used ranged from 5 to 80% and 5 to 95% for PS of <300 nm and >300 nm, respectively, the efficiencies improved when multiple layers were used and when using a specific combination of different fabrics. Filtration efficiencies of the hybrids was >80% (PS <300 nm) and >90% (PS>300 nm). Cotton, the most widely used material for cloth masks performs better at higher weave densities (i.e., thread count) and can make a significant difference in filtration efficiencies. Our studies also imply that gaps (as caused by an improper fit of the mask) can result in over a 60% decrease in the filtration efficiency” |
• N95 respirator |
Particles dimension: 0.01–10 µm. |
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Air flow: 35 L/min and 90 L/min. |
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Analysis: filtration efficiency (%) and airflow resistance (ΔP). |
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Experiments were repeated seven times for each fabric and mask types. |