Masks are not only essential they are in vogue. Influencers, community leaders, sheros, heros and theroes are modeling how to save lives when social distancing with a minimum of 6 feet between humans and sporting a mask.
The Design Corps researchers, producers and designers continue to conduct research and publish research findings that inform personal protective equipment design and usability. The following #MaskUp 101 sections should serve as a living document designed as a public service informing all constituents about the public health benefits of mask usage.
Lexicon & Language
Face Mask: A face mask is personal protective equipment designed to protect your from respiratory illnesses caused by pollution, bacteria and viruses.
Face Mask Filters: Face mask filters are used to filter out particles, irritants and viruses. Not all filters are the same. The Design Corps' recommends the usage of non-toxic MERV-13 filters.
MERV: Minimum Efficiency Reporting Value. MERV reports a filter's ability to capture larger particles between 0.3 and 10 microns (µm).
HEPA is a type of pleated mechanical air filter. It is an acronym for high efficiency particulate air
PM2.5: The term fine particles, or particulate matter 2.5 (PM2.5), refers to tiny particles or droplets in the air that are two and one half microns or less in width. Like inches, meters and miles, a micron is a unit of measurement for distance. There are about 25,000 microns in an inch. The widths of the larger particles in the PM2.5 size range would be about thirty times smaller than that of a human hair. The smaller particles are so small that several thousand of them could fit on the period at the end of this sentence.
Ear Loops: Cloth or elastic loops that fit behind the ear to ensure the face mask stays in place over your nose and mouth.
Ear Savers: A face mask accessory that reduces ear distress and irritation offering a proper fit for users.
Eucalyptus Lyocell: Eucalyptus as a material is known as Tencel Lyocell. It is made from the pulp of eucalyptus trees. Thanks to a partnership with Sheets & Giggles our 3-Layer couture masks use Eucalyptus Lyocell materials made out of wood, which is turned into a pulp via a closed-loop lyocell process before that pulp is turned into yarn. The best part about Sheets & Giggles Lyocell is that nearly 100% of the solvents from each batch are reused in the next, so there's almost zero waste.
Mask Selection & Fitting Criteria
Not all masks are made the same. While any face covering is better than none, there are 4 important features you should consider when purchasing a mask:
- Mask Supply: Essential professionals still face personal protective shortages across the globe. This is more acute in the Black, LatinX, Indigenous and impoverished communities. N95, Surgical and Medical Masks should be reserved for essential professionals who are serving their communities and have medical waste disposal procedures. e.g. Healthcare, Agriculture and Food Service, Transportation and Educators.
- Mask Fit: Masks and face coverings should be designed to fit snugly over your mouth and nose. To get the best fit, take measurements from the bridge of your nose to the bottom tip of your chin. The mask should eliminate air gaps and offer a seal. When masks are combined with Ear Savers they enable people to adjust the fit behind the ears with a tighter seal for longer comfort.
- Mask Filtration: For 3-Layer sewn or couture masks, look for masks with 3-Layers. If you can see through the mask it does not offer enough protection. 3-Layers of materials like 100% Cotton and 100% Eucalyptus Lyocell provide up to 75% filtration. When combined with a pocket for MERV-13 or PM2.5 Filter, the filtration increases (see 3-layer testing below). For 3D Printed respirator masks like the Breathe3D mask that use antimicrobial filaments and MERV-13 and above Filters can provide up to 95% filtration when properly fitted.
- Mask Reusability & Sustainability: According to the world economic forum: Coronavirus waste has become a new form of pollution as single-use personal protective equipment (PPE) floods our ocean. Disposable medical masks are creating dangerous medical wastes in our communities on land and in waterways and oceans. Reusable masks made of 100% Cotton, Eucalyptus Lyocell and Antimicrobial filaments provide a sustainable solution to reduce the dangerous medical pollution.
- Mask Comfort: Masks should offer breathability. 100% cotton and Eucalyptus Lyocell provide breathability and comfort in active environments. Rounded elastic, Ear Saves and Headbands with buttons reduce ear chafing. If you have dry skin, it's best to put on moisturizer before wearing a mask. This can help prevent skin irritation from where the mask rubs your face. If you have oily skin, you may want to avoid wearing a liquid foundation as that can clog your pores and cause your skin to break out. Not to mention, the foundation can also rub off on your mask, leading to decreased air filtration, making it harder to breathe.
Mask Usability: Designing Healthy Habits
When it comes to everyday use, a 3-Layer sewn couture or Breathe3D face mask is recommended. By not using surgical masks and N95 respirators, you help preserve those resources for health care professionals. We know practice makes perfect. Here are 10 behaviors, when repeated daily for 6 weeks will turn into new healthy habits.
- 2+ MaskUp: Masks should be worn by all humans ages 2 years and older. Face coverings should NOT be worn by children under the age of 2 or anyone who has trouble breathing, is unconscious, incapacitated, or otherwise unable to remove the mask without assistance.
- Eliminate Touch: Never Touch the outside of the mask while it is on your face. If you do wash hands and sanitize reusable masks.
- Not A chin guard: Do not wear your mask around your chin exposing your mouth and nose. Masks should stay on your face fitted over your mouth and nose.
- Don’t Share Your Mask: Masks are for personal hygiene and should not be shared.
- Stop Mask Dangle: Masks should not dangle or appear loose around your ears. Ear Savers help deliver a comfortable fit of mask 3-Layer or Breathe3D Respirator Masks.
- Stop PPE Pollution: Disposable N95 and medical masks are made for 1 time usage in medical environments that have proper medical waste disposal systems. Use reusable, rewash-able face masks that aim to reduce PPE Pollution.
- Proper Mask Storage: Masks should be stored in a clean, dry space. Masks should not be stored in a purse or a pocket without a protective case or bag encasing your mask.
- Masking Up: Before placing a mask on your face, first clean your hands with soap and water or with a hand sanitizer, then using ear loops place secure the mask over your nose, fitted at the tip or just below the tip of your chin. The mask should snuggly cover your nose and mouth. Once your mask is on your face, wash your hands and do not touch the outside of the mask.
- Mask Removal: When removing the mask, first clean your hands with soap and water or with a hand sanitizer, then remove your mask. After removing your mask, wash or sanitize your hands again.
- Sustainable Reusable Masks: Sustainable masks will save us from a new mutated pandemic. Gently, wash your mask daily and replace your filters often!
100M Mask Mayday Studio Program Published Research
The following research was used to inform the 100M Mask Mayday Studio Program Design Requirements:
2 and 3-Layer Mask Testing & Filtration
Properly fitted masks made with 3 layers of 600+ thread count of 100% Cotton and or Eucalyptus Lyocell can offer up to approximately 74-79% filtration. See the test results below.
Infectious respiratory illnesses can exact a heavy socio-economic toll on the most vulnerable members of our society, as has become evident from the current COVID-19 pandemic.1,2 The disease has overwhelmed healthcare infrastructure worldwide,3 and its high contagion rate and relatively long incubation period4,5 have made it difficult to trace and isolate infected individuals. Current estimates indicate that about 35% of infected individuals do not display overt symptoms6 and may contribute to the significant spread of the disease without their knowledge. In an effort to contain the unabated community spread of the disease, public health officials have recommended the implementation of various preventative measures, including social-distancing and the use of face masks in public settings.7
While detailed quantitative measurements are necessary for the comprehensive characterization of PPE, qualitative visualizations can be invaluable for rapid iteration in early design stages, as well as for demonstrating the proper use of such equipment. Thus, one of the aims of this Letter is to describe a simple setup for visualization experiments, which can be assembled using easily available materials.
KN95 Masks & Efficacy
The U.S. Food and Drug Administration has removed its Emergency Use Authorization for several KN95 masks, which are made in China, after they failed to meet a minimum particulate filtration efficiency of 95% in National Institute for Occupational Safety and Health testing. Some KN95 masks that initially were authorized failed subsequent National Institute for Occupational Safety and Health testing and cannot be relied upon as respirators. These include masks manufactured by:
• CTT Co. Ltd.
• Daddybaby Co. Ltd.
• Dongguan Xianda Medical Equipment Co. Ltd.
• Guangdong Fei Fan Mstar Technology Ltd.
• Guangdong Nuokang Medical Technology Co. Ltd.
• Huizhou Huinuo Technology Co. Ltd.
• Lanshan Shendun Technology Co.
For a full list of personal protective equipment authorized for emergency use by the FDA, go to the agency's Emergency Use Authorizations webpage.
See Research References Below.
100M Mask Mayday Requirements Made Real
The Design Corps' couture masks & 3D Printed PPE have used the research above to inform the invention and design of 3-Layer couture masks and Essential3D Products which include Breathe3D masks, Shield3D face shields, Filter3D MERV-13 Filters, Goggle3D eye protection and EarSave3D Ear savers.
Essential3D Products: a brand of 3D printed products invented and produced by the DesignedByUs.org Design Corps to solve PPE shortages across the globe.
Breathe3D Masks: The Breathe3D mask is a 3D Printed mask designed to protect you from injury or the spread of infection or illness. The Breathe3D mask is made with FDA-compliant, ISO-certified, Antibacterial 3D Printing Filaments and hospital grade, reusable, washable MERV-13 filters. When fitted to your face, the Breathe3D mask achieves approximately 95% filtration.
Filter3D MERV-13 Filters: 2.5 inch x 2.5 inch squares of AiRx Health filters that trap and lock ultra fine particles that effect your health.
Goggle3D Eye Protection: 3D printed protective goggles.
EarRescue3D Ear Savers: Ear savers are mask accessories that reduce tugging ear distress. Ear savers will not just make your mask more comfortable to wear—they also function as a new fashion accessory that you can mix and match with your masks.
- United Nations, “A UN framework for the immediate socio-economic response to COVID-19,” Technical Report, United Nations, April 2020, available at https://unsdg.un.org/sites/default/files/2020-04/UN-framework-for-the-immediate-socio-economic-response-to-COVID-19.pdf. Google Scholar
- M. Nicola, Z. Alsafi, C. Sohrabi, A. Kerwan, A. Al-Jabir, C. Iosifidis, M. Agha, and R. Agha, “The socio-economic implications of the coronavirus pandemic (COVID-19): A review,” Int. J. Surg. 78, 185–193 (2020). https://doi.org/10.1016/j.ijsu.2020.04.018, Google Scholar Crossref
- E. J. Emanuel, G. Persad, R. Upshur, B. Thome, M. Parker, A. Glickman, C. Zhang, C. Boyle, M. Smith, and J. P. Phillips, “Fair allocation of scarce medical resources in the time of covid-19,” N. Engl. J. Med. 382, 2049–2055 (2020). https://doi.org/10.1056/nejmsb2005114, Google Scholar Crossref
- S. A. Lauer, K. H. Grantz, Q. Bi, F. K. Jones, Q. Zheng, H. R. Meredith, A. S. Azman, N. G. Reich, and J. Lessler, “The incubation period of coronavirus disease 2019 (COVID-19) from publicly reported confirmed cases: Estimation and application,” Ann. Intern. Med. 172, 577–582 (2020). https://doi.org/10.7326/m20-0504, Google Scholar Crossref
- X. He, E. H. Y. Lau, P. Wu, X. Deng, J. Wang, X. Hao, Y. C. Lau, J. Y. Wong, Y. Guan, X. Tan, X. Mo, Y. Chen, B. Liao, W. Chen, F. Hu, Q. Zhang, M. Zhong, Y. Wu, L. Zhao, F. Zhang, B. J. Cowling, F. Li, and G. M. Leung, “Temporal dynamics in viral shedding and transmissibility of COVID-19,” Nat. Med. 26, 672–675 (2020). https://doi.org/10.1038/s41591-020-0869-5, Google Scholar Crossref
- Centers for Disease Control and Prevention, “COVID-19 pandemic planning scenarios,” https://www.cdc.gov/coronavirus/2019-ncov/hcp/planning-scenarios. html, May 2020. Google Scholar
- Centers for Disease Control and Prevention, “Social distancing, quarantine, and isolation,” https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/ social-distancing.html, May 2020. Google Scholar
- C. R. MacIntyre, S. Cauchemez, D. E. Dwyer, H. Seale, P. Cheung, G. Browne, M. Fasher, J. Wood, Z. Gao, R. Booy, and N. Ferguson, “Face mask use and control of respiratory virus transmission in households,” Emerging Infect. Dis. 15, 233–241 (2009). https://doi.org/10.3201/eid1502.081166, Google Scholar Crossref
- C. R. MacIntyre and A. A. Chughtai, “A rapid systematic review of the efficacy of face masks and respirators against coronaviruses and other respiratory transmissible viruses for the community, healthcare workers and sick patients,” Int. J. Nurs. Stud. 108, 103629 (2020). https://doi.org/10.1016/j.ijnurstu.2020.103629, Google Scholar Crossref
- L. Morawska, “Droplet fate in indoor environments, or can we prevent the spread of infection?,” Indoor Air 16, 335–347 (2006). https://doi.org/10.1111/j.1600-0668.2006.00432.x, Google ScholarCrossref
- S. Stelzer-Braid, B. G. Oliver, A. J. Blazey, E. Argent, T. P. Newsome, W. D. Rawlinson, and E. R. Tovey, “Exhalation of respiratory viruses by breathing, coughing, and talking,” J. Med. Virol. 81, 1674–1679 (2009). https://doi.org/10.1002/jmv.21556, Google Scholar Crossref
- L. Morawska, G. R. Johnson, Z. D. Ristovski, M. Hargreaves, K. Mengersen, S. Corbett, C. Y. H. Chao, Y. Li, and D. Katoshevski, “Size distribution and sites of origin of droplets expelled from the human respiratory tract during expiratory activities,” J. Aerosol Sci. 40, 256–269 (2009). https://doi.org/10.1016/j.jaerosci.2008.11.002, Google Scholar Crossref
- C. Chen, C.-H. Lin, Z. Jiang, and Q. Chen, “Simplified models for exhaled airflow from a cough with the mouth covered,” Indoor Air 24, 580–591 (2014). https://doi.org/10.1111/ina.12109, Google ScholarCrossref
- V. Stadnytskyi, C. E. Bax, A. Bax, and P. Anfinrud, “The airborne lifetime of small speech droplets and their potential importance in SARS-CoV-2 transmission,” Proc. Natl. Acad. Sci. U. S. A. 117, 11875–11877 (2020). https://doi.org/10.1073/pnas.2006874117, Google Scholar Crossref
- P. Bahl, C. Doolan, C. de Silva, A. A. Chughtai, L. Bourouiba, and C. R. MacIntyre, “Airborne or droplet precautions for health workers treating COVID-19?,” J. Infect. Dis. 2020, 1–8. https://doi.org/10.1093/infdis/jiaa189, Google ScholarCrossref
- L. C. Jennings and E. C. Dick, “Transmission and control of rhinovirus colds,” European Journal of Epidemiology 3, 327–335 (1987). https://doi.org/10.1007/bf00145641, Google ScholarCrossref
- Centers for Disease Control and Prevention, “Core curriculum on tuberculosis: What the clinician should know,” Technical Report CS234269, 2013, available at https://www.cdc.gov/tb/education/corecurr/pdf/corecurr_all.pdf. Google Scholar
- J. S. Kutter, M. I. Spronken, P. L. Fraaij, R. A. Fouchier, and S. Herfst, “Transmission routes of respiratory viruses among humans,” Curr. Opin. Virol. 28, 142–151 (2018). https://doi.org/10.1016/j.coviro.2018.01.001, Google Scholar Crossref
- R. Tellier, Y. Li, B. J. Cowling, and J. W. Tang, “Recognition of aerosol transmission of infectious agents: A commentary,” BMC Infect. Dis. 19, 1–9 (2019). https://doi.org/10.1186/s12879-019-3707-y, Google Scholar Crossref
- R. Tellier, “Review of aerosol transmission of influenza A virus,” Emerging Infect. Dis. 12, 1657–1662 (2006). https://doi.org/10.3201/eid1211.060426, Google ScholarCrossref
- A. Fernstrom and M. Goldblatt, “Aerobiology and its role in the transmission of infectious diseases,” J. Pathog. 2013, 1–13. https://doi.org/10.1155/2013/493960, Google ScholarCrossref
- J. W. Tang, C. J. Noakes, P. V. Nielsen, I. Eames, A. Nicolle, Y. Li, and G. S. Settles, “Observing and quantifying airflows in the infection control of aerosol- and airborne-transmitted diseases: An overview of approaches,” J. Hosp. Infect. 77, 213–222 (2011). https://doi.org/10.1016/j.jhin.2010.09.037, Google ScholarCrossref
- J. W. Tang, Y. Li, I. Eames, P. K. S. Chan, and G. L. Ridgway, “Factors involved in the aerosol transmission of infection and control of ventilation in healthcare premises,” J. Hosp. Infect. 64, 100–114 (2006). https://doi.org/10.1016/j.jhin.2006.05.022, Google ScholarCrossref
- S. W. Zhu, S. Kato, and J.-H. Yang, “Study on transport characteristics of saliva droplets produced by coughing in a calm indoor environment,” Build. Environ. 41, 1691–1702 (2006). https://doi.org/10.1016/j.buildenv.2005.06.024, Google ScholarCrossref
- X. Xie, Y. Li, A. T. Y. Chwang, P. L. Ho, and W. H. Seto, “How far droplets can move in indoor environments—Revisiting the Wells evaporation–falling curve,” Indoor Air 17, 211–225 (2007). https://doi.org/10.1111/j.1600-0668.2007.00469.x, Google ScholarCrossref
- S. Liu and A. Novoselac, “Transport of airborne particles from an unobstructed cough jet,” Aerosol Sci. Technol. 48, 1183–1194 (2014). https://doi.org/10.1080/02786826.2014.968655, Google ScholarCrossref
- H. Nishimura, S. Sakata, and A. Kaga, “A new methodology for studying dynamics of aerosol particles in sneeze and cough using a digital high-vision, high-speed video system and vector analyses,” PLoS One 8, e80244 (2013). https://doi.org/10.1371/journal.pone.0080244, Google ScholarCrossref
- J. Gralton, E. Tovey, M.-L. McLaws, and W. D. Rawlinson, “The role of particle size in aerosolised pathogen transmission: A review,” J. Infect. 62, 1–13 (2011). https://doi.org/10.1016/j.jinf.2010.11.010, Google ScholarCrossref
- Z. Y. Han, W. G. Weng, and Q. Y. Huang, “Characterizations of particle size distribution of the droplets exhaled by sneeze,” J. R. Soc., Interface 10, 20130560 (2013). https://doi.org/10.1098/rsif.2013.0560, Google ScholarCrossref
- C. Y. Chao, M. P. Wan, L. Morawska, G. R. Johnson, Z. D. Ristovski, M. Hargreaves, K. Mengersen, S. Corbett, Y. Li, X. Xie, and D. Katoshevski, “Characterization of expiration air jets and droplet size distributions immediately at the mouth opening,” J. Aerosol Sci. 40, 122–133 (2009). https://doi.org/10.1016/j.jaerosci.2008.10.003, Google ScholarCrossref
- W. F. Wells, “On air-borne infection: Study II. Droplets and droplet nuclei,” Am. J. Epidemiol. 20, 611–618 (1934). https://doi.org/10.1093/oxfordjournals.aje.a118097, Google ScholarCrossref
- J. P. Duguid, “The size and the duration of air-carriage of respiratory droplets and droplet-nuclei,” J. Hyg. 44, 471–479 (1946). https://doi.org/10.1017/S0022172400019288, Google ScholarCrossref
- J. W. Tang, T. J. Liebner, B. A. Craven, and G. S. Settles, “A schlieren optical study of the human cough with and without wearing masks for aerosol infection control,” J. R. Soc., Interface 6, 727–736 (2009). https://doi.org/10.1098/rsif.2009.0295.focus, Google ScholarCrossref
- L. Bourouiba, E. Dehandschoewercker, and J. W. Bush, “Violent expiratory events: On coughing and sneezing,” J. Fluid Mech. 745, 537–563 (2014). https://doi.org/10.1017/jfm.2014.88, Google ScholarCrossref
- L. Bourouiba, “Turbulent gas clouds and respiratory pathogen emissions: Potential implications for reducing transmission of COVID-19,” JAMA, J. Am. Med. Assoc. 323, 1837–1838 (2020). https://doi.org/10.1001/jama.2020.4756, Google ScholarCrossref
- M. Nicas, W. W. Nazaroff, and A. Hubbard, “Toward understanding the risk of secondary airborne infection: Emission of respirable pathogens,” J. Occup. Environ. Hyg. 2, 143–154 (2005). https://doi.org/10.1080/15459620590918466, Google ScholarCrossref
- Y. Liu, Z. Ning, Y. Chen, M. Guo, Y. Liu, N. K. Gali, L. Sun, Y. Duan, J. Cai, D. Westerdahl, X. Liu, K. Xu, K.-f. Ho, H. Kan, Q. Fu, and K. Lan, “Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospitals,” Nature (published online 2020). https://doi.org/10.1038/s41586-020-2271-3, Google ScholarCrossref
- S. W. X. Ong, Y. K. Tan, P. Y. Chia, T. H. Lee, O. T. Ng, M. S. Y. Wong, and K. Marimuthu, “Air, surface environmental, and personal protective equipment contamination by severe Acute respiratory Syndrome coronavirus 2 (SARS-CoV-2) from a symptomatic patient,” JAMA, J. Am. Med. Assoc. 323, 1610–1612 (2020). https://doi.org/10.1001/jama.2020.3227, Google ScholarCrossref
- J. Cai, W. Sun, J. Huang, M. Gamber, J. Wu, and G. He, “Indirect virus transmission in cluster of COVID-19 cases, wenzhou, China, 2020,” Emerging Infect. Dis. 26, 1343–1345 (2020). https://doi.org/10.3201/eid2606.200412, Google ScholarCrossref
- B. E. Scharfman, A. H. Techet, J. W. Bush, and L. Bourouiba, “Visualization of sneeze ejecta: Steps of fluid fragmentation leading to respiratory droplets,” Exp. Fluids 57, 1–9 (2016). https://doi.org/10.1007/s00348-015-2078-4, Google ScholarCrossref
- G. B. Ha’eri and A. M. Wiley, “The efficacy of standard surgical face masks: An investigation using “tracer particles”,” Clin. Orthop. Relat. Res. 148, 160–162 (1980). https://doi.org/10.1097/00003086-198005000-00024, Google ScholarCrossref
- D. F. Johnson, J. D. Druce, C. Birch, and M. L. Grayson, “A quantitative assessment of the efficacy of surgical and N95 masks to filter influenza virus in patients with acute influenza infection,” Clin. Infect. Dis. 49, 275–277 (2009). https://doi.org/10.1086/600041, Google ScholarCrossref
- W. G. Lindsley, W. P. King, R. E. Thewlis, J. S. Reynolds, K. Panday, G. Cao, and J. V. Szalajda, “Dispersion and exposure to a cough-generated aerosol in a simulated medical examination room,” J. Occup. Environ. Hyg. 9, 681–690 (2012). https://doi.org/10.1080/15459624.2012.725986, Google ScholarCrossref
- W. G. Lindsley, J. D. Noti, F. M. Blachere, J. V. Szalajda, and D. H. Beezhold, “Efficacy of face shields against cough aerosol droplets from a cough simulator,” J. Occup. Environ. Hyg. 11, 509–518 (2014). https://doi.org/10.1080/15459624.2013.877591, Google ScholarCrossref
- G. Zayas, M. C. Chiang, E. Wong, F. Macdonald, C. F. Lange, A. Senthilselvan, and M. King, “Effectiveness of cough etiquette maneuvers in disrupting the chain of transmission of infectious respiratory diseases,” BMC Public Health 13, 1–11 (2013). https://doi.org/10.1186/1471-2458-13-811, Google ScholarCrossref
- N. H. L. Leung, D. K. W. Chu, E. Y. C. Shiu, K.-H. Chan, J. J. McDevitt, B. J. P. Hau, H.-L. Yen, Y. Li, D. K. M. Ip, J. S. M. Peiris, W.-H. Seto, G. M. Leung, D. K. Milton, and B. J. Cowling, “Respiratory virus shedding in exhaled breath and efficacy of face masks,” Nat. Med. 26, 676–680 (2020). https://doi.org/10.1038/s41591-020-0843-2, Google ScholarCrossref
- S. S. Zhou, S. Lukula, C. Chiossone, R. W. Nims, D. B. Suchmann, and M. K. Ijaz, “Assessment of a respiratory face mask for capturing air pollutants and pathogens including human influenza and rhinoviruses,” J. Thorac. Dis. 10, 2059–2069 (2018). https://doi.org/10.21037/jtd.2018.03.103, Google ScholarCrossref
- S. Rengasamy, B. Eimer, and R. E. Shaffer, “Simple respiratory protection—Evaluation of the filtration performance of cloth masks and common fabric materials against 20-1000 nm size particles,” Ann. Occup. Hyg. 54, 789–798 (2010). https://doi.org/10.1093/annhyg/meq044, Google ScholarCrossref
- A. Davies, K.-A. Thompson, K. Giri, G. Kafatos, J. Walker, and A. Bennett, “Testing the efficacy of homemade masks: Would they protect in an influenza pandemic?,” Disaster Med. Public Health Preparedness 7, 413–418 (2013). https://doi.org/10.1017/dmp.2013.43, Google ScholarCrossref
- S. Bae, M.-C. Kim, J. Y. Kim, H.-H. Cha, J. S. Lim, J. Jung, M.-J. Kim, D. K. Oh, M.-K. Lee, S.-H. Choi, M. Sung, S.-B. Hong, J.-W. Chung, and S.-H. Kim, “Effectiveness of surgical and cotton masks in blocking SARS-CoV-2: A controlled comparison in 4 patients,” Ann. Intern. Med. M20, 1342 (2020). https://doi.org/10.7326/m20-1342, Google ScholarCrossref
- A. Konda, A. Prakash, G. A. Moss, M. Schmoldt, G. D. Grant, and S. Guha, “Aerosol filtration efficiency of common fabrics used in respiratory cloth masks,” ACS Nano 14, 6339–6347 (2020). https://doi.org/10.1021/acsnano.0c03252, Google ScholarCrossref
- S. Feng, C. Shen, N. Xia, W. Song, M. Fan, and B. J. Cowling, “Rational use of face masks in the COVID-19 pandemic,” Lancet Respir. Med. 8, 434–436 (2020). https://doi.org/10.1016/s2213-2600(20)30134-x, Google ScholarCrossref
- J. Xiao, E. Y. C. Shiu, H. Gao, J. Y. Wong, M. W. Fong, S. Ryu, and B. J. Cowling, “Nonpharmaceutical measures for pandemic influenza in non healthcare settings-personal protective and environmental measures,” Emerging Infect. Dis. 26, 967–975 (2020). https://doi.org/10.3201/eid2605.190994, Google ScholarCrossref
- J. K. Gupta, C.-H. Lin, and Q. Chen, “Flow dynamics and characterization of a cough,” Indoor Air 19, 517–525 (2009). https://doi.org/10.1111/j.1600-0668.2009.00619.x, Google ScholarCrossref
- J. Y. Hsu, R. Stone, R. Logan-Sinclair, M. Worsdell, C. Busst, and K. Chung, “Coughing frequency in patients with persistent cough: Assessment using a 24 hour ambulatory recorder,” Eur. Respir. J. 7, 1246–1253 (1994). https://doi.org/10.1183/09031936.94.07071246, Google ScholarCrossref
- E. Bjorn and P. V. Nielsen, “Dispersal of exhaled air and personal exposure in displacement ventilated rooms,” Indoor Air 12, 147–164 (2002). https://doi.org/10.1034/j.1600-0668.2002.08126.x, Google ScholarCrossref
- H. Qian, Y. Li, P. V. Nielsen, C. E. Hyldgaard, T. W. Wong, and A. T. Y. Chwang, “Dispersion of exhaled droplet nuclei in a two-bed hospital ward with three different ventilation systems,” Indoor Air 16, 111–128 (2006). https://doi.org/10.1111/j.1600-0668.2005.00407.x, Google ScholarCrossref
- Y. Li, G. M. Leung, J. W. Tang, X. Yang, C. Y. Chao, J. Z. Lin, J. W. Lu, P. V. Nielsen, J. Niu, H. Qian, A. C. Sleigh, H.-J. Su, J. Sundell, T. W. Wong, and P. L. Yuen, “Role of ventilation in airborne transmission of infectious agents in the built environment–A multidisciplinary systematic review,” Indoor Air 17, 2–18 (2007). https://doi.org/10.1111/j.1600-0668.2006.00445.x, Google ScholarCrossref
- T. Dbouk and D. Drikakis, “On coughing and airborne droplet transmission to humans,” Phys. Fluids 32, 053310 (2020). https://doi.org/10.1063/5.0011960, Google ScholarScitation, ISI
- Centers for Disease Control and Prevention (CDC), “How to Make Your own Face Covering,” https://www.youtube.com/watch?v=tPx1yqvJgf4, 2020. Google Scholar