MakerMask

Masks for COVID: Literature Highlights

Image of a man wearing a mask and reading from a journal. Photo source: freepik.com

In this post we share some of our favorite articles about mask science. Since the beginning of this pandemic over 6000 papers have been published on masks. For scientists and sewists alike, sorting through all this information can be daunting! We have gathered our top recommendations for those looking to join us in immersing themselves in the literature and also provide a long list of additional articles. The articles focus on reusable masks for COVID, including those constructed with nonwoven polypropylene (NWPP). As regular readers of MakerMask likely recognize, spunbond NWPP is a leading candidate for fabric masks, and we share publications that quantify filtration and breathability of NWPP relative to other materials.

Overview of Masks for COVID

For people looking for an introductory overview on masks, we recommend this accessible yet science-based review.

General

Peeples, L “Face masks: what the data say”, Nature 586, 186-189 (October 6, 2020)

Masks 2020 Nature Paper image of person using a mask as a parachute

This review article offers an accessible overview of face masks, including the changing understanding of community masks through 2020, a discussion of what particle sizes dominate, the importance of mask fit, differences in filtration between fabrics, the human psychology around mask wearing, and the politics behind public messaging.

Fabric Filtration and Breathability (with focus on NWPP)

The publications by Long, Zangmeister, and Zhou provide quantitative test data on NWPP and other mask materials, evaluating the tradeoffs between breathability and filtration. Additional layers of fabric increase filtration but reduce breathability. However not all fabrics have the same trade-offs; one layer of cotton will result in a greater loss of breathability than one layer of NWPP, with lesser improvement in filtration. In the papers, you will see these two metrics combined into the “Q factor”. We like NWPP because it performs better (has a higher “Q factor”) than cottons, polyesters, and other common sewing fabrics. 

Finally, in reading these papers, note whether the material tested was spunbond or meltblown polypropylene. Meltblown polypropylenes are unsuitable for washing and thus we do not recommend them for reusable masks whereas spunbond polypropylenes (e.g., SmartFab and OlyFun) can withstand multiple washings. 

Fabric Filtration and Breathability (with focus on NWPP)

Long, Kenneth D et al. “Measurement of filtration efficiencies of healthcare and consumer materials using modified respirator fit tester setup.” PLoS One. October 13, 2020; 15(10): e0240499.

Illustration of the Long et al Mask Filtration Testing Setup

 

Relevant to sewists because the study tested readily accessible materials. The best performers were non-woven polypropylenes, including some materials with both spunbond and meltblown (Halyard H100 and H500) or with spunbond only (Pellon 915 interfacing, and SmartFab).

MakerMask take-away: Spunbond non-woven polypropylene including SmartFab and Pellon 915 have a good balance of filtration and breathability, and so are a good choice for multi-layer masks.

In more detail: Developed a test setup that approximates NIOSH testing standards with standard hospital fit-testing equipment plus <$300 of additional equipment. Used slightly smaller particles than NIOSH mandates, with a median count diameter less than half that of a coronavirus. Demonstrated that alternative mask materials can be used to achieve filtration efficiencies approaching those of N95 respirators.Table S2 in the supplemental materials is worth viewing.

Zangmeister CD, Radney JG, Vicenzi EP, Weaver JL. “Filtration Efficiencies of Nanoscale Aerosol by Cloth Mask Materials Used to Slow the Spread of SARS-CoV-2.” ACS Nano. June 25, 2020;14(7):9188-200.

Summary showing that filtration increases with increaseing numbers of mask layers

Relevant to sewists because they tested a large number of fabric types. The non-woven polypropylenes (meltblown only) generally performed better than cottons, polyesters, and other fabrics. 

MakerMask take-away: As the number of layers increases, the filtration also increases and breathability decreases. Beyond 5 layers is too hard to breathe. 

In more detail: Tested over 40 materials including cottons, polyesters, blends, paper towel, and polypropylenes. The meltblown polypropylenes (HEPA Filter, medical wrap, N95, surgical masks) had a higher Q factor than most other materials. Used 50 to 825nm NaCl aerosol particles, in accordance with standards. Filtration vs particle size follows the expected curve with a low ~200nm and better filtration of larger particles. Electrostatic deposition seems to be not significant in filtration by cloth materials. Plots of cotton flannel filtration versus number of layers suggest that the first layer provides more filtration than each subsequent layer. 

Zhao M, et al. “Household Materials Selection for Homemade Cloth Face Coverings and Their Filtration Efficiency Enhancement with Triboelectric Charging” Nano Lett. June 2, 2020, 20, 5544-5552

Electron Microscopy of Mask Fabrics

Relevant to sewists because they tested spunbond polypropylene interfacing, a fabric type readily accessible by the yard to sewists.

MakerMask take-away: Spunbond non-woven polypropylene has a good balance between filtration and breathability, making it a good choice for multi-layer masks.

In more detail: Fabric samples were tested with a modified NIOSH procedure, modified to use 32 L/min instead of 85 L/min (NaCl, 0.075 +/-0.2 um count median diameter, 0.26 μm mass mean diameter). They tested a broad range of materials meltblowns (N95, medical mask), spunbond (interfacing), and other fabrics (cottons, polyester, silk, nylon, paper products). Measured filtration and pressure drop, and calculated the Q factor. N95 had the best Q, polypropylene was 2nd best, with the rest of the materials roughly similar and lagging the top two. Also included evaluation of triboelectric charging. Supplemental materials include multi-layer testing of 1 to 5 layers of spunbond polypropylene.

 

Mask Efficacy

Masks reduce COVID-19 transmission and severity, as evidenced both by studies on human populations and by well-controlled hamster experiments. These studies can help us make a well considered decision when selecting the right mask for the right task such as a three-layer fabric masks for community use versus respirators for use in high-risk settings. 

Mask efficacy

“Human Studies of Masking and SARS-CoV-2 Transmission” section of “Science Brief: Community Use of Cloth Masks to Control the Spread of SARS-CoV-2”.
U.S. Centers for Disease Control
Relevant to sewists because this is an accessible and succinct summary of masks reducing spread of Covid in human communities.

MakerMask take-away: Masks work, as shown in human population studies.

In more detail: The first part summarizes studies of small and clearly defined populations, such as 139 clients of infected hairstylists or 124 Beijing households or an outbreak on a ship, with disease transmission reduced by 70% to 100% with mask usage. The second part references broader community analyses, where masking reduced infection rates in larger and less bounded populations.

“Surgical Mask Partition Reduces the Risk of Noncontact Transmission in a Golden Syrian Hamster Model for Coronavirus Disease 2019 (COVID-19)” Jasper Fuk-Woo Chan, et al. Clinical Infectious Diseases, Volume 71, Issue 16, 15 October 2020,p. 2139-2149

 

Relevant to sewists because this study showed that surgical masks reduced but did not fully stop transmission of Covid in hamsters in a well-controlled experiment. Also, masks reduced the severity of the transmitted disease. Both these findings support use of masks to reduce community transmission but not as PPE.

MakerMask take-away: Masks work, as shown in well-controlled animal studies.

In more detail: Some hamsters were inoculated with SARS-CoV-2 and then placed in cages next to healthy (naive) hamsters, either with or without a surgical mask as a barrier between cages. Rates and severity of disease in the naive hamsters were assessed.

Conclusion

As these paper demonstrate, masks work. However, the science of which mask fabrics are best for reusable masks is still evolving. The good news is that as new studies emerge, we are finding more refinement and greater scientific consensus to aid in the construction of better masks. Despite the many differences in the literature, the basic lessons remain the same: 1) when selecting fabrics for masks, select materials and layers that give you a good balance of breathability and filtration and 2) spunbond NWPP provides a better balance than other common sewing fabrics like cottons and polyesters. 

What are your favorite scientific articles and why? We’d love to hear from you in the comments.

 

Additional References

Mask Guidelines & Standards

Original Research – Mask Fabrics

  • Guha S, Herman A, et al (January 13, 2020). Comprehensive characterization of protective face coverings made from household fabrics. PLoS One. 2021 Jan 13;16(1):e0244626. doi: 10.1371/journal.pone.0244626. PMID: 33439878.
  • Kolewe EL, Stillman Z, Woodward IR, Fromen CA. (December 16, 2020) Check the gap: Facemask performance and exhaled aerosol distributions around the wearer. PLoS One. 2020;15(12):e0243885. Published 2020 Dec 16. doi:10.1371/journal.pone.0243885
  • Clapp PW, Sickbert-Bennett EE, et al (December 10, 2020); US Centers for Disease Control and Prevention Epicenters Program. Evaluation of Cloth Masks and Modified Procedure Masks as Personal Protective Equipment for the Public During the COVID-19 Pandemic. JAMA Intern Med. 2020 Dec 10. doi: 10.1001/jamainternmed.2020.8168. Epub ahead of print. PMID: 33300948.
  • Grigg SE, Zampiron A, Akbaridoust F, et al. (November 2020) Are surgical masks manufactured from sterilisation wrap safe? [published online ahead of print, 2020 Nov 19]. Infect Dis Health. 2020;doi:10.1016/j.idh.2020.11.001. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7674969/ 
  • Sousan S, Garcia N, White A, Balanay JA. (November 2020) Filtration Efficiency of Surgical Sterilization Fabric for Respiratory Protection during COVID-19 Pandemic [published online ahead of print, 2020 Nov 6]. Am J Infect Control. 2020;S0196-6553(20)30974-3. doi:10.1016/j.ajic.2020.11.005
  • Wang D, You Y, Zhou X, et al. (October 15, 2020) Selection of homemade mask materials for preventing transmission of COVID-19: A laboratory study. PLoS One. 2020;15(10):e0240285. Published 2020 Oct 15. doi:10.1371/journal.pone.0240285
  • Long, Kenneth D et al. (October 13, 2020) “Measurement of filtration efficiencies of healthcare and consumer materials using modified respirator fit tester setup.” PloS one vol. 15,10 e0240499. 13 Oct. 2020, doi:10.1371/journal.pone.0240499 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7553287/ 
  • Parlin AF, Stratton SM, Culley TM, Guerra PA. (September 18, 2020) A laboratory-based study examining the properties of silk fabric to evaluate its potential as a protective barrier for personal protective equipment and as a functional material for face coverings during the COVID-19 pandemic. PLoS One. 2020 Sep 18;15(9):e0239531. doi: 10.1371/journal.pone.0239531. PMID: 32946526; PMCID: PMC7500605. Accessed at https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0239531 on Nov. 23, 2020
  • Lee KP, Yip J, Kan CW, Chiou JC, Yung KF (September, 2020). Reusable Face Masks as Alternative for Disposable Medical Masks: Factors that Affect their Wear-Comfort. Int J Environ Res Public Health. 2020;17(18):6623. Published 2020 Sep 11. doi:10.3390/ijerph17186623. Accessed at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7558362/ on Nov. 23, 2020
  • Aydin O, Emon MAB, Cheng S, et al. (October, 2020) Performance of Fabrics for Home-Made Masks Against the Spread of Respiratory Infections Through Droplets: A Quantitative Mechanistic Study. Extreme Mechanics Letters, Volume 40, 2020, 100924,ISSN 2352-4316, https://doi.org/10.1016/j.eml.2020.100924.
  • Fischer EP, Fischer MC, Grass D, Henrion I, Warren WS, Westman E. (September 2020) Low-cost measurement of face mask efficacy for filtering expelled droplets during speech. Sci Adv. 2020 Sep 2;6(36):eabd3083. doi: 10.1126/sciadv.abd3083. PMID: 32917603; PMCID: PMC7467698. https://aip.scitation.org/doi/10.1063/5.0029767 
  • Mueller AV, Eden MJ, Oakes JM, Bellini C, Fernandez LA. (July/Sept. 2020) Quantitative Method for Comparative Assessment of Particle Removal Efficiency of Fabric Masks as Alternatives to Standard Surgical Masks for PPE. Matter. 2020;3(3):950-962. doi:10.1016/j.matt.2020.07.006 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7346791/ 
  • Asadi S, Cappa CD, Barreda S, Wexler AS, Bouvier NM, Ristenpart WD. (September 2020) Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities. Sci Rep. 2020;10(1):15665. Published 2020 Sep 24. doi:10.1038/s41598-020-72798-7 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7518250/ 
  • Zangmeister CD, Radney JG, Vicenzi EP, Weaver JL. (July 2020) Filtration Efficiencies of Nanoscale Aerosol by Cloth Mask Materials Used to Slow the Spread of SARS-CoV-2. ACS Nano. 2020 Jul 28;14(7):9188-9200. doi: 10.1021/acsnano.0c05025. Epub 2020 Jul 7. PMID: 32584542; PMCID: PMC7341689.
  • Rodriguez-Palacios A, Cominelli F, Basson AR, Pizarro TT, Ilic S. (May 2020) Textile Masks and Surface Covers-A Spray Simulation Method and a “Universal Droplet Reduction Model” Against Respiratory Pandemics. Front Med (Lausanne). 2020;7:260. Published 2020 May 27. doi:10.3389/fmed.2020.00260. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7267001/ 
  • Bagheri et al. (PREPRINT, 2020). Filtration  Efficiency,  Breathability,  and  Reusability of Improvised Materials for Face Masks. https://engrxiv.org/nrtgb/?fbclid=IwAR2Gt0rZeop6h-8fskyTT-wxypxpVqd9g4ZA48NHzd81s_eSv8Lc8Q7gwIY 
  • Hill WC, Hull MS, MacCuspie RI. (September 2020) Testing of Commercial Masks and Respirators and Cotton Mask Insert Materials using SARS-CoV-2 Virion-Sized Particulates: Comparison of Ideal Aerosol Filtration Efficiency versus Fitted Filtration Efficiency. Nano Lett. 2020 Oct 14;20(10):7642-7647. doi: 10.1021/acs.nanolett.0c03182. Epub 2020 Sep 29. PMID: 32986441; PMCID: PMC7534799.
  • Konda A, Prakash A, Moss GA, Schmoldt M, Grant GD, Guha S. (May 2020) Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks. ACS Nano. 2020 May 26;14(5):6339-6347. doi: 10.1021/acsnano.0c03252. Epub 2020 Apr 24. Erratum in: ACS Nano. 2020 Aug 25;14(8):10742-10743. PMID: 32329337; PMCID: PMC7185834.

Mask Efficacy & Washing

  • MacIntyre CR, Dung TC, Chughtai AA, et al. (September 2020) Contamination and washing of cloth masks and risk of infection among hospital health workers in Vietnam: a post hoc analysis of a randomised controlled trialBMJ Open 2020;10:e042045. doi: 10.1136/bmjopen-2020-042045 https://bmjopen.bmj.com/content/bmjopen/10/9/e042045.full.pdf 
  • MacIntyre CR, Seale H, Dung TC, et al. (April 2015) A cluster randomised trial of cloth masks compared with medical masks in healthcare workers. BMJ Open. 2015;5(4):e006577. Published 2015 Apr 22. doi:10.1136/bmjopen-2014-006577 

Preprint Articles To Watch

Caution is warranted when interpreting preprint articles as they have not yet undergone peer review. However, they may provide interesting insights into the evolving science

  • Courtney JM, Bax A. (December 26, 2020) Hydrating the Respiratory Tract: An Alternative Explanation Why Masks Lower Severity of COVID-19 Disease. Preprint. medRxiv. 2020;2020.12.23.20248671. Published 2020 Dec 26. doi:10.1101/2020.12.23.20248671, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781334/ 
  • Gopal, Vikram et al. (November 4, 2020) “Zinc-embedded fabrics inactivate SARS-CoV-2 and influenza A virus.” bioRxiv : the preprint server for biology 2020.11.02.365833. 4 Nov. 2020, doi:10.1101/2020.11.02.365833. Preprint.

Review/Commentary – Masks

  • Kumar S. and Lee H.P. (Nov. 24, 2020) The perspective of fluid flow behavior of respiratory droplets and aerosols through the facemasks in context of SARS-CoV-2. Physics of Fluids 32, 111301 (2020); https://doi.org/10.1063/5.0029767 
  • Karim N, Afroj S, Lloyd K, et al. (Oct. 27, 2020) Sustainable Personal Protective Clothing for Healthcare Applications: A Review. ACS Nano. 2020;14(10):12313-12340. doi:10.1021/acsnano.0c0553. Accessed at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7518242/ on Nov. 23, 2020 
  • Chughtai AA, Seale H, Macintyre CR. (Oct. 2020) Effectiveness of Cloth Masks for Protection Against Severe Acute Respiratory Syndrome Coronavirus 2. Emerg Infect Dis. 2020;26(10):e200948. doi:10.3201/eid2610.200948. Accessed at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7510705/ on Nov. 23, 2020
  • Beesoon S, Behary N, Perwuelz A. (Oct. 2020) Universal masking during COVID-19 pandemic: Can textile engineering help public health? Narrative review of the evidence. Prev Med. 2020;139:106236. doi:10.1016/j.ypmed.2020.106236
  • Chua et al (Aug. 2020), “Face Masks in the New COVID-19 Normal: Materials, Testing, and Perspectives”, Research, vol. 2020, Article ID 7286735, 40 pages, 2020. https://doi.org/10.34133/2020/7286735 
  • Clase CM et al, (July 31, 2020). Forgotten Technology in the COVID-19 Pandemic: Filtration Properties of Cloth and Cloth Masks-A Narrative Review. Mayo Clin Proc. 2020 Oct;95(10):2204-2224. doi: 10.1016/j.mayocp.2020.07.020. Epub 2020 Jul 31. PMID: 33012350. (https://www.clothmasks.ca/)

Masks Recycling, & Microplastics

  • Parashar N, Hait S. (March 2021) Plastics in the time of COVID-19 pandemic: Protector or polluter?. Sci Total Environ. 2021;759:144274. doi:10.1016/j.scitotenv.2020.144274
  • Battegazzore D, Cravero F, Frache A. (Nov. 17, 2020) Is it Possible to Mechanical Recycle the Materials of the Disposable Filtering Masks?. Polymers (Basel). 2020;12(11):2726. Published 2020 Nov 17. doi:10.3390/polym12112726 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7698554/
  • Shruti VC, Pérez-Guevara F, Elizalde-Martínez I, Kutralam-Muniasamy G. (October 2020) Reusable masks for COVID-19: A missing piece of the microplastic problem during the global health crisis [published online ahead of print, 2020 Oct 20]. Mar Pollut Bull. 2020;161(Pt B):111777. doi:10.1016/j.marpolbul.2020.111777, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7574683/
  • Li L, Zhao X, Li Z, Song K. (July 2020) COVID-19: Performance study of microplastic inhalation risk posed by wearing masks. J Hazard Mater. 2021;411:124955. doi:10.1016/j.jhazmat.2020.12495 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7773316/ 

COVID-19 Disease Transmission (Droplets, Aerosols etc)

Preprint Server:

  • Port JR, Yinda CK, Owusu IO, et al. (December 28, 2020 – Preprint Server) SARS-CoV-2 disease severity and transmission efficiency is increased for airborne but not fomite exposure in Syrian hamsters. Preprint. bioRxiv. 2020;2020.12.28.424565. Published 2020 Dec 28. doi:10.1101/2020.12.28.424565 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781302/ 
  • Morris et al. (December 18, 2020 – Preprint) Mechanistic theory predicts the effects of temperature and humidity on inactivation of SARS-CoV-2 and other enveloped viruses external icon. bioRxiv.

Peer Reviewed:

  • Popa A, Genger JW, Nicholson MD, et al. (Nov. 23, 2020) Genomic epidemiology of superspreading events in Austria reveals mutational dynamics and transmission properties of SARS-CoV-2. Sci Transl Med. 2020 Nov 23:eabe2555. doi: 10.1126/scitranslmed.abe2555. Epub ahead of print. PMID: 33229462. Accessed at https://stm.sciencemag.org/content/early/2020/11/20/scitranslmed.abe2555.short on Nov. 30, 2020

Mathematical Model of Disease Transmission and Masks

  • Akhtar J, Garcia AL, Saenz L, Kuravi S, Shu F, Kota K. (December 2020) Can face masks offer protection from airborne sneeze and cough droplets in close-up, face-to-face human interactions?-A quantitative study. Phys Fluids (1994). 2020;32(12):127112. doi:10.1063/5.0035072
  • Shang Y, Tao Y, Dong J, He F, Tu J. (May 2021) Deposition features of inhaled viral droplets may lead to rapid secondary transmission of COVID-19. J Aerosol Sci. 2021;154:105745. doi:10.1016/j.jaerosci.2021.105745
  • Mittal R, Meneveau C, Wu W. (Oct. 1, 2020) A mathematical framework for estimating risk of airborne transmission of COVID-19 with application to face mask use and social distancing. Phys Fluids (1994). 2020 Oct 1;32(10):101903. doi: 10.1063/5.0025476. PMID: 33100806; PMCID: PMC7583361.
  • Mapping COVID-19 R Values: http://metrics.covid19-analysis.org/

Droplet/Aerosol Visualization/Propagation

  • Darby S, Chulliyallipalil K, Przyjalgowski M, et al. (December 22, 2020) COVID-19: mask efficacy is dependent on both fabric and fit. Future Microbiol. 2021;16:5-11. doi:10.2217/fmb-2020-0292
  • Staymates, Matthew. (November 1, 2020) “Flow visualization of an N95 respirator with and without an exhalation valve using schlieren imaging and light scattering.” Physics of fluids (Woodbury, N.Y. : 1994) vol. 32,11 (2020): 111703. doi:10.1063/5.0031996
  • Arumuru V, Pasa J, Samantaray SS. (November 2020) Experimental visualization of sneezing and efficacy of face masks and shields. Phys Fluids (1994). 2020 Nov 1;32(11):115129. doi: 10.1063/5.0030101. PMID: 33244217; PMCID: PMC7684680.

Fabric Mask Acoustics / Speech / Singing

Featured Review: 

  • Naunheim MR, Bock J, et al (Review – July 2020). Safer Singing During the SARS-CoV-2 Pandemic: What We Know and What We Don’t. J Voice. 2020 Jul 2:S0892-1997(20)30245-9. doi: 10.1016/j.jvoice.2020.06.028. Epub ahead of print. PMID: 32753296; PMCID: PMC7330568.

Other Articles:

  • Bottalico P, Murgia S, Puglisi GE, Astolfi A, Kirk KI. (November 2020) Effect of masks on speech intelligibility in auralized classrooms. J Acoust Soc Am. 2020 Nov;148(5):2878. doi: 10.1121/10.0002450. PMID: 33261397.
  • Corey RM, Jones U, Singer AC. (October 2020) Acoustic effects of medical, cloth, and transparent face masks on speech signals. J Acoust Soc Am. 2020 Oct;148(4):2371. doi: 10.1121/10.0002279. PMID: 33138498.
  • Patel RK, Shackelford IA, Priddy MC, Kopechek JA. (October 2020) Effect of speech volume on respiratory emission of oral bacteria as a potential indicator of pathogen transmissibility risk. J Acoust Soc Am. 2020 Oct;148(4):2322. doi: 10.1121/10.0002278. PMID: 33138475.
  • Echternach M, Gantner S, et al (October 2020). Impulse Dispersion of Aerosols During Singing and Speaking: A Potential COVID-19 Transmission Pathway. Am J Respir Crit Care Med. 2020 Oct 16. doi: 10.1164/rccm.202009-3438LE. Epub ahead of print. PMID: 33064957.
  • Bahl P, de Silva C et al (September 2020). Droplets and Aerosols generated by singing and the risk of COVID-19 for choirs. Clin Infect Dis. 2020 Sep 18:ciaa1241. doi: 10.1093/cid/ciaa1241. Epub ahead of print. PMID: 32945338; PMCID: PMC7543379.
  • Helding L, Carroll TL, Nix J, Johns MM, LeBorgne WD, Meyer D. (August 2020) COVID-19 After Effects: Concerns for Singers. J Voice. 2020 Aug 6:S0892-1997(20)30281-2. doi: 10.1016/j.jvoice.2020.07.032. Epub ahead of print. PMID: 32839055; PMCID: PMC7409791.
  • Gregson; Watson; Orton; Haddrell; McCarthy; Finnie; et al. (Preprint – August 2020): Comparing the Respirable Aerosol Concentrations and Particle Size Distributions Generated by Singing, Speaking and Breathing. ChemRxiv. Preprint. https://doi.org/10.26434/chemrxiv.12789221.v1
  • Ingo R. Titze (Review – 2013). A Short Tutorial on Sound Level and Loudness for Voice, Journal of Singing, November/December 2013 Volume 70, No. 2, pp. 191–192

Mask CO2

Nanotechnology, Textiles, & Safety

  • Lee, Hye Ryoung et al. (December 7, 2020) “Three-Dimensional Analysis of Particle Distribution on Filter Layers inside N95 Respirators by Deep Learning.” Nano letters vol. 21,1 (2021): 651-657. doi:10.1021/acs.nanolett.0c04230
  • Saleem H, Zaidi SJ. (November 13, 2020; review) Sustainable Use of Nanomaterials in Textiles and Their Environmental Impact. Materials (Basel). 2020;13(22):5134. Published 2020 Nov 13. doi:10.3390/ma13225134
  • Bandi MM. (November 2020) Electrocharged facepiece respirator fabrics using common materials. Proc Math Phys Eng Sci. 2020;476(2243):20200469. doi:10.1098/rspa.2020.0469
  • Hernández-Sánchez, F., Herrera-Franco, P. (2001) Electrical and thermal properties of recycled polypropylene-carbon black composites. Polymer Bulletin 45, 509–516 (2001). https://doi.org/10.1007/s002890170105.

Adverse Effects/Rashes (Acne & Dermatitis & Itch)

  • Teo WL. (February 12, 2021) The “Maskne” microbiome – pathophysiology and therapeutics. Int J Dermatol. 2021 Feb 12. doi: 10.1111/ijd.15425. Epub ahead of print. PMID: 33576511.
  • Chaiyabutr C, Sukakul T, Pruksaeakanan C, Thumrongtharadol J, Boonchai W. (December 21, 2020) Adverse skin reactions following different types of mask usage during the COVID-19 pandemic [published online ahead of print, 2020 Nov 21]. J Eur Acad Dermatol Venereol. 2020;10.1111/jdv.17039. doi:10.1111/jdv.17039
  • Krajewski PK, Matusiak Ł, Szepietowska M, Białynicki-Birula R, Szepietowski JC. (December 2020) Increased Prevalence of Face Mask-Induced Itch in Health Care Workers. Biology (Basel). 2020 Dec 7;9(12):E451. doi: 10.3390/biology9120451. PMID: 33297438.
  • Battista RA, Ferraro M, Piccioni LO, Malzanni GE, Bussi M. (December 2020) Personal Protective Equipment (PPE) in COVID 19 Pandemic: Related Symptoms and Adverse Reactions in Healthcare Workers and General Population. J Occup Environ Med. 2020 Dec 3. doi: 10.1097/JOM.0000000000002100. Epub ahead of print. PMID: 33298757.
  • Searle T, Ali FR, Al-Niaimi F (November 2020). Identifying and addressing ‘Maskne’ in clinical practice. Dermatol Ther. 2020 Nov 26:e14589. doi: 10.1111/dth.14589. Epub ahead of print. PMID: 33244836.
  • Daye M, Cihan FG, Durduran Y (September 2020). Evaluation of skin problems and dermatology life quality index in health care workers who use personal protection measures during COVID-19 pandemic [published online ahead of print, 2020 Sep 28]. Dermatol Ther. 2020;e14346. doi:10.1111/dth.14346
  • Erik Birgersson ,Ee Ho Tang,Wei Liang Jerome Lee,Kwok Jiang Sak. (November 2020) Reduction of Carbon Dioxide in Filtering Facepiece Respirators with an Active-Venting System: A Computational Study. Published: June 26, 2015. Accessed at https://doi.org/10.1371/journal.pone.0130306 on Nov. 23, 2020
  • Szczepan S, Michalik K, Borkowski J, Zatoń K. (February 2020) Effects of Swimming with Added Respiratory Dead Space on Cardiorespiratory Fitness and Lipid Metabolism. J Sports Sci Med. 2020;19(1):95-101. Published 2020 Feb 24. Accessed at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7039034/ on Nov. 23, 2020
  • CDC Occupational Health Guideline for Carbon Dioxide. Accessed at https://www.cdc.gov/niosh/docs/81-123/pdfs/0103.pdf?id=10.26616/NIOSHPUB81123 on Nov. 23, 2020
  • Davis BA, Tsen LC. (September 2020) Wearing an N95 Respiratory Mask: An Unintended Exercise Benefit? Anesthesiology. 2020 Sep;133(3):684-686. doi: 10.1097/ALN.0000000000003421. PMID: 32467450; PMCID: PMC7268846. Accessed at https://pubmed.ncbi.nlm.nih.gov/32467450/ on Nov. 23, 2020
  • ISO/TS 16976-3:2019 (2019) Respiratory protective devices — Human factors — Part 3: Physiological responses and limitations of oxygen and limitations of carbon dioxide in the breathing environment. Accessed at https://www.iso.org/standard/73209.html Nov. 23, 2020 (full text on file)
  • Mark S Siobal,(2016) Monitoring Exhaled Carbon Dioxide, Respiratory Care October 2016, 61 (10) 1397-1416; DOI: https://doi.org/10.4187/respcare.04919. Accessed at http://rc.rcjournal.com/content/61/10/1397 on Nov. 23, 2020
  • Smith CL, Whitelaw JL, Davies B. (2013) Carbon dioxide rebreathing in respiratory protective devices: influence of speech and work rate in full-face masks. Ergonomics. 2013 ;56(5):781-790. DOI: 10.1080/00140139.2013.777128. Accessed at https://europepmc.org/article/med/23514282 on Nov. 23, 2020, also accessed at https://ro.uow.edu.au/cgi/viewcontent.cgi?article=1836&context=smhpapers on Nov. 23, 2020
  • Wikipedia Dead Space Reference: https://en.wikipedia.org/wiki/Dead_space_(physiology)#:~:text=In%20humans%2C%20about%20a%20third,tube%2C%20such%20as%20a%20snorkel

Quantitative Fit Testing

  • O’Kelly E, Arora A, Pirog S, Ward J, Clarkson PJ. (January 22, 2021) Comparing the fit of N95, KN95, surgical, and cloth face masks and assessing the accuracy of fit checking. PLoS One. 2021;16(1):e0245688. Published 2021 Jan 22. doi:10.1371/journal.pone.0245688
Masks for COVID: Literature Highlights

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