Wear a mask - it's airborne!

Table of Contents

  1. N95, FFP2, KF94, KN95 and CN95
  2. We knew from the start that masks would help slow or stop even the pandemic
    1. Pre-pandemic articles
    2. Articles written during the pandemic
    3. Goddard’s Journal - listing the “masks work” studies
  3. Scientific studies of masks and respirators
    1. Systematic and meta-analyses of masks and respirators
    2. Actual studies (not meta-analyses)
    3. Narrative reviews
  4. Anti-masker activities

Until ventilation laws are enacted and building owners roll out change to increase fresh air, HEPA/MERV filter stale air and use CO2 monitors to gauge proximate transmission risks, your only way to be confident about protecting yourself inside shard-air spaces is to wear a mask. We realize that most people in 2024 are not wearing masks for protection at all. Understand that a few people still are, and that they ignore the comments they get.

There were lies about masks and respirators from the start of the pandemic. Ignore them, all masks work, but they vary from 10% protective up to 99.9%. Here’s the definitive study: Masks and respirators for prevention of respiratory infections: a state of the science review - Greenhalgh et al, 2024.

The difference between N95, FFP2, KF94, KN95 and CN95

If you can afford it, get N95/KF94 grade masks (that are not cloth or washable) for use when mixing with other in public. Citizen Scientist, Aaron Collins, reviews masks for filtration effectiveness and talks about KF94 masks quite a bit, but there are many standards now.

From the fall of 2020 onwards, Aaron Collins with the equipment he had at his home tests high-filtration masks he’s acquired for filtration and leakage. One of the stars of “masks for all” in the pandemic.

We knew from the start that masks would help slow or even stop the pandemic.

Pre-pandemic articles suggesting masks in particular would work

Here are some articles written during the pandemic supporting the use of masks

Wikipedia Maintains a long page on mask use in the pandemic here

Goddard’s Journal - listing the “masks work” studies

Goddard’s Journal was among the very first to gather the studies that proved masks work. The author did the work that many governments did not, disproving the lies told about masks.

Goddard’s first video - March 2020

Timings from start of video:

Goddard’s second video - October 2020

This was a follow up to the first, as noted at the start of the video. Timings from start of video:

Scientific studies of masks and respirators

Studies of the use of masks/respirators, thread 🧵. From https://mastodon.social/@jmcrookston/111689874254752367

1. Systematic reviews and meta-analyses of masks and respirators

Summary of the studies listed below

This summary should be accurate but double-check it yourself. Don’t forget about all the limitations of meta-analyses. They have their own intrinsic biases and, of course, are no better than their underlying studies.

The following studies found a statistically significant difference between the data relating tomMasks/respirators and not. This suggests the result (that masks work in the contexts of these trials) was unlikely to be due to random chance.

The followng studes did not find a statistically significant difference between the data relating to masks/respirators and not. All we can say is we cannot rule out that these results arose by random chance (at the statistical level selected by the authors). Authors’ comments are noted.

The studies

2016 Smith, Jeffrey D., Colin C. MacDougall, Jennie Johnstone, Ray A. Copes, Brian Schwartz, and Gary E. Garber. ‘Effectiveness of N95 Respirators versus Surgical Masks in Protecting Health Care Workers from Acute Respiratory Infection: A Systematic Review and Meta-Analysis’. CMAJ: Canadian Medical Association Journal = Journal de l’Association Medicale Canadienne 188, no. 8 (17 May 2016): 567–74. https://doi.org/10.1503/cmaj.150835.

2017 MacIntyre, Chandini Raina, Abrar Ahmad Chughtai, Bayzidur Rahman, Yang Peng, Yi Zhang, Holly Seale, Xiaoli Wang, and Quanyi Wang. ‘The Efficacy of Medical Masks and Respirators against Respiratory Infection in Healthcare Workers’. Influenza and Other Respiratory Viruses 11, no. 6 (2017): 511–17. https://doi.org/10.1111/irv.12474.

2017-11. Offeddu, Vittoria, Chee Fu Yung, Mabel Sheau Fong Low, and Clarence C. Tam. ‘Effectiveness of Masks and Respirators Against Respiratory Infections in Healthcare Workers: A Systematic Review and Meta-Analysis’. Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America 65, no. 11 (13 November 2017): 1934–42. https://doi.org/10.1093/cid/cix681.

2020-05. Long, Youlin, Tengyue Hu, Liqin Liu, Rui Chen, Qiong Guo, Liu Yang, Yifan Cheng, Jin Huang, and Liang Du. ‘Effectiveness of N95 Respirators versus Surgical Masks against Influenza: A Systematic Review and Meta-Analysis’. Journal of Evidence-Based Medicine 13, no. 2 (May 2020): 93–101. https://doi.org/10.1111/jebm.12381.

2020-07. Bartoszko, Jessica J., Mohammed Abdul Malik Farooqi, Waleed Alhazzani, and Mark Loeb. ‘Medical Masks vs N95 Respirators for Preventing COVID-19 in Healthcare Workers: A Systematic Review and Meta-Analysis of Randomized Trials’. Influenza and Other Respiratory Viruses 14, no. 4 (July 2020): 365–73. https://doi.org/10.1111/irv.12745.

2020-10. Chou, Roger, Tracy Dana, Rebecca Jungbauer, Chandler Weeks, and Marian S. McDonagh. ‘Masks for Prevention of Respiratory Virus Infections, Including SARS-CoV-2, in Health Care and Community Settings : A Living Rapid Review’. Annals of Internal Medicine 173, no. 7 (6 October 2020): 542–55. https://doi.org/10.7326/M20-3213.

2020 Barycka. ‘Comparative Effectiveness of N95 Respirators and Surgical/Face Masks in Preventing Airborne Infections in the Era of SARS-CoV2 Pandemic: A Meta-Analysis of Randomized Trials’. PloS One 15, no. 12 (2020): e0242901. https://doi.org/10.1371/journal.pone.0242901.

2020 Iannone, Primiano, Greta Castellini, Daniela Coclite, Antonello Napoletano, Alice Josephine Fauci, Laura Iacorossi, Daniela D’Angelo, et al. ‘The Need of Health Policy Perspective to Protect Healthcare Workers during COVID-19 Pandemic. A GRADE Rapid Review on the N95 Respirators Effectiveness’. PloS One 15, no. 6 (2020): e0234025. https://doi.org/10.1371/journal.pone.0234025.

2022-05. Kunstler, Breanne, Skye Newton, Hayley Hill, John Ferguson, Phillipa Hore, Brett G. Mitchell, Kathy Dempsey, et al. ‘P2/N95 Respirators & Surgical Masks to Prevent SARS-CoV-2 Infection: Effectiveness & Adverse Effects’. Infection, Disease & Health 27, no. 2 (May 2022): 81–95. https://doi.org/10.1016/j.idh.2022.01.001.

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Nanda, Akriti, Ivan Hung, Ava Kwong, Vivian Chi‐Mei Man, Pankaj Roy, Lucy Davies, and Michael Douek. “Efficacy of Surgical Masks or Cloth Masks in the Prevention of Viral Transmission: Systematic Review, Meta‐analysis, and Proposal for Future Trial.” Journal of Evidence-Based Medicine, February 9, 2021, 10.1111/jebm.12424. https://doi.org/10.1111/jebm.12424.

Ollila, Hanna M., Markku Partinen, Jukka Koskela, John Borghi, Riikka Savolainen, Anna Rotkirch, and Liisa T. Laine. “Face Masks to Prevent Transmission of Respiratory Infections: Systematic Review and Meta-Analysis of Randomized Controlled Trials on Face Mask Use.” PLOS ONE 17, no. 12 (December 1, 2022): e0271517. https://doi.org/10.1371/journal.pone.0271517.

SeyedAlinaghi, SeyedAhmad, Amirali Karimi, Amir Masoud Afsahi, Pegah Mirzapour, Sanaz Varshochi, Hengameh Mojdeganlou, Paniz Mojdeganlou, et al. “The Effectiveness of Face Masks in Preventing COVID-19 Transmission: A Systematic Review.” Infectious Disorders Drug Targets, June 1, 2023. https://doi.org/10.2174/1871526523666230601090905.

Boulos, Leah, Janet A. Curran, Allyson Gallant, Helen Wong, Catherine Johnson, Alannah Delahunty-Pike, Lynora Saxinger, et al. “Effectiveness of Face Masks for Reducing Transmission of SARS-CoV-2: A Rapid Systematic Review.” Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences 381, no. 2257 (n.d.): 20230133. https://doi.org/10.1098/rsta.2023.0133.

MacIntyre, C. Raina, and Abrar Ahmad 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.” International Journal of Nursing Studies 108 (August 2020): 103629. https://doi.org/10.1016/j.ijnurstu.2020.103629.

2. Narrative reviews (summaries of studies)

Schünemann, Holger J., Elie A. Akl, Roger Chou, Derek K. Chu, Mark Loeb, Tamara Lotfi, Reem A. Mustafa, et al. ‘Use of Facemasks during the COVID-19 Pandemic’. The Lancet. Respiratory Medicine 8, no. 10 (October 2020): 954–55. https://doi.org/10.1016/S2213-2600(20)30352-0.

Regli, A., A. Sommerfield, and B. S. von Ungern-Sternberg. “The Role of Fit Testing N95/FFP2/FFP3 Masks: A Narrative Review.” Anaesthesia 76, no. 1 (January 2021): 91–100. https://doi.org/10.1111/anae.15261.

Howard, Jeremy, Austin Huang, Zhiyuan Li, Zeynep Tufekci, Vladimir Zdimal, Helene-Mari van der Westhuizen, Arne von Delft, et al. “An Evidence Review of Face Masks against COVID-19.” Proceedings of the National Academy of Sciences 118, no. 4 (January 26, 2021). https://doi.org/10.1073/pnas.2014564118.

3. Studies (actual studies, so excludes meta-analyses)

Radonovich, Lewis J., Michael S. Simberkoff, Mary T. Bessesen, Alexandria C. Brown, Derek A. T. Cummings, Charlotte A. Gaydos, Jenna G. Los, et al. ‘N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel: A Randomized Clinical Trial’. JAMA 322, no. 9 (3 September 2019): 824–33. https://doi.org/10.1001/jama.2019.11645.

Ueki, Hiroshi, Yuri Furusawa, Kiyoko Iwatsuki-Horimoto, Masaki Imai, Hiroki Kabata, Hidekazu Nishimura, and Yoshihiro Kawaoka. “Effectiveness of Face Masks in Preventing Airborne Transmission of SARS-CoV-2.” mSphere, October 21, 2020. https://doi.org/10.1128/mSphere.00637-20.

“The N95 mask had the highest protective efficacy (approximately 80% to 90% reduction) of the various masks examined; however, infectious virus penetration was measurable even when the N95 mask was completely fitted to the face with adhesive tape (Fig. 2B). In contrast, when a mask was attached to the mannequin that released virus, cotton and surgical masks blocked more than 50% of the virus transmission, whereas the N95 mask showed considerable protective efficacy (Fig. 2C). There was a synergistic effect when both the virus receiver and virus spreader wore masks (cotton masks or surgical masks) to prevent the transmission of infective droplets/aerosols (Fig. 2D and E).” ([Ueki et al., 2020, p. 3]

Ferris, Mark, Rebecca Ferris, Chris Workman, Eoin O’Connor, David A Enoch, Emma Goldesgeyme, Natalie Quinnell, et al. “Efficacy of FFP3 Respirators for Prevention of SARS-CoV-2 Infection in Healthcare Workers.” Edited by Jos W Van der Meer, Sarah Logan, and Stephanie Evans. eLife 10 (November 16, 2021): e71131. https://doi.org/10.7554/eLife.71131.

“Results: Whilst using FRSMs, HCWs working on red wards faced an approximately 31-fold (and at least fivefold) increased risk of direct, ward-based infection. Conversely, after changing to FFP3 respirators, this risk was significantly reduced (52–100% protection). Conclusions: FFP3 respirators may therefore provide more effective protection than FRSMs for HCWs caring for patients with COVID-19, whether or not AGPs are undertaken.” ([Ferris et al., 2021, p. 1]

https://academic.oup.com/pnasnexus/advance-article/doi/10.1093/pnasnexus/pgae065/7606553

2. Studies of masks as source control

Lai, Jianyu, Kristen K. Coleman, S.-H. Sheldon Tai, Jennifer German, Filbert Hong, Barbara Albert, Yi Esparza, et al. “Relative Efficacy of Masks and Respirators as Source Control for Viral Aerosol Shedding from People Infected with SARS-CoV-2: A Controlled Human Exhaled Breath Aerosol Experimental Study.” eBioMedicine 104 (June 1, 2024). https://doi.org/10.1016/j.ebiom.2024.105157.

Verma, Siddhartha, Manhar Dhanak, and John Frankenfield. “Visualizing the Effectiveness of Face Masks in Obstructing Respiratory Jets.” Physics of Fluids 32, no. 6 (June 1, 2020): 061708. https://doi.org/10.1063/5.0016018.

Epidemiological studies

2021 Dec. Missouri health department found mask mandates work, but didn’t make findings public. “Jurisdictions with mask mandates averaged 15.8 cases per day for every 100,000 residents, compared to 21.7 in unmasked communities. https://archive.ph/EK5tt.

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Loeb study (2009) and its criticisms

Loeb, Mark, Nancy Dafoe, James Mahony, Michael John, Alicia Sarabia, Verne Glavin, Richard Webby, et al. “Surgical Mask vs N95 Respirator for Preventing Influenza among Health Care Workers: A Randomized Trial.” JAMA 302, no. 17 (November 4, 2009): 1865–71. https://doi.org/10.1001/jama.2009.1466.

criticisms:

Bitar, Roger. “Surgical Masks vs N95 Respirators for Preventing Influenza.” JAMA 303, no. 10 (March 10, 2010): 937; author reply 938-939. https://doi.org/10.1001/jama.2010.193.

Clynes, Neville. “Surgical Masks vs N95 Respirators for Preventing Influenza.” JAMA 303, no. 10 (March 10, 2010): 937–38; author reply 938-939. https://doi.org/10.1001/jama.2010.194.

Finkelstein, Yaron, Tal Schechter, and Stephen B. Freedman. “Surgical Masks vs N95 Respirators for Preventing Influenza.” JAMA 303, no. 10 (March 10, 2010): 938; author reply 938-939. https://doi.org/10.1001/jama.2010.195.

Palen, Ted E., and Kate G. Felix. “Surgical Masks vs N95 Respirators for Preventing Influenza.” JAMA 303, no. 10 (March 10, 2010): 937; author reply 938-939. https://doi.org/10.1001/jama.2010.192.

Anti-Masker activities

Anti-masker groups are motivated by politics, hatred of your group/country, bad science, and more. They link to things they claim can prove their case, but which are always based on bad science or logic.

Their bogus talking points:

Raina MacIntyre’s work in particular

Study ‘MacIntyre et al, 2015’, figures quite a lot as an anti-masker “truth”. Goddard’s Journal went into this study above. Meanwhile, Raina C MacIntyre is disgusted with mis-representation by anti-masker groups. She has published more in the last eighteen months to further indicate her science that masks actually work and that we should wear them: