119 Studies and Articles Undercutting Utility of Masks for Stopping Covid

#	Summary	Date	Source
1	1920 AJPH: San Francisco's 1918 mask order showed no effect on influenza spread; masks 'not proved efficient enough' to mandate	01/01/1920	American Journal of Public Health
2	1985 lab study: surgical masks show large face-seal leakage and poor filtration of particles under 5 microns	06/01/1985	NIH National Library of Medicine
3	Operating-room study: unmasked staff did not contaminate the table; masks for non-scrubbed staff 'unnecessary'	07/18/1991	NIH National Library of Medicine
4	1992 study: surgical masks passed 25–80% of submicron aerosols depending on material and airflow	08/20/1992	NIH National Library of Medicine
5	Surgical mask filters let 20% to nearly 100% of submicron particles through; face-seal leaks worsen it	08/21/1993	NIH National Library of Medicine
6	Strathclyde thesis: masks make wearers feel less identifiable and reduce self-awareness, a disinhibiting effect	01/01/1999	University of Strathclyde
7	70% of dialysis patients wearing N95s saw blood oxygen fall; 19% developed hypoxemia	08/10/2004	NIH National Library of Medicine
8	Systematic review: no RCT evidence that surgeons' masks prevent surgical wound infection	09/23/2005	NIH National Library of Medicine
9	37% of health workers wearing N95s during SARS reported mask-related headaches; a third had them 6+ times a month	03/11/2006	NIH National Library of Medicine
10	Hong Kong preschoolers masked during 2003 SARS showed less social interaction and couldn't read facial expressions	06/01/2006	International Journal of Early Childhood
11	Nearly 100% of surgical masks and 29% of N95s failed to meet protection factor against virus-sized particles	03/07/2008	NIH National Library of Medicine
12	Hong Kong household pilot: too few flu transmissions to detect any effect of masks or hand hygiene	05/07/2008	National Library of Medicine
13	Surgeons' blood oxygen fell and pulse rose after one hour in surgical masks, especially those over 35	11/19/2008	Neurocirugía
14	Sydney household RCT: masks did not reduce flu-like illness; adherence was under 50% (note: adherent wearers saw benefit)	02/01/2009	National Library of Medicine
15	Japan RCT of health workers: masks did not reduce colds; mask wearers reported more headaches	02/12/2009	NIH National Library of Medicine
16	Hong Kong household RCT: masks and hand hygiene reduced flu transmission only if started within 36 hours (note: mixed finding)	10/06/2009	National Library of Medicine
17	2010 systematic review: some evidence masks protect others when worn by the sick, 'fewer data' they protect the wearer	01/22/2010	Epidemiology and Infection
18	University dorm RCT: masks plus hand hygiene 'may reduce' flu-like illness (note: finding supports masks)	02/15/2010	National Library of Medicine
19	New York household RCT: no detectable benefit of masks or hand sanitizer over education alone on respiratory infections	03/31/2010	National Library of Medicine
20	N95s raised CO2 and lowered oxygen in the mask dead space, but caused no significant physiological change in health workers	05/01/2010	NIH National Library of Medicine
21	Cloth masks and fabrics let 40–90% of virus-sized particles through, far worse than N95 media	06/28/2010	NIH National Library of Medicine
22	Bangkok household RCT: hand washing and face masks did not reduce influenza transmission	07/05/2011	National Library of Medicine
23	UK Health Protection Agency review: scientific evidence for masks and respirators against flu is scarce	12/21/2011	Influenza and Other Respiratory Viruses
24	University dorm RCT: masks plus hand hygiene cut flu-like illness; masks alone did not (note: mixed finding)	01/25/2012	National Library of Medicine
25	Berlin household RCT: masks and hand hygiene reduced flu transmission when started early (note: finding supports masks)	01/26/2012	National Library of Medicine
26	Homemade cotton masks half as well-fitted and one-third as effective as surgical masks; 'last resort' only	08/07/2013	NIH National Library of Medicine
27	Vietnam RCT of 1,607 health workers: cloth masks had the highest infection rates, 97% particle penetration	04/22/2015	NIH National Library of Medicine
28	Ontario arbitrator strikes down hospital vaccinate-or-mask rule: 'insufficient medical evidence' masks cut flu transmission	09/21/2015	Canadian Lawyer
29	Pregnant health workers breathing through N95 material had 23% lower tidal volume and reduced oxygen uptake	11/16/2015	NIH National Library of Medicine
30	Review of 25 mass-gathering studies: masks showed a small protective effect, RR 0.89 (note: finding supports masks)	04/01/2016	NIH National Library of Medicine
31	Cochrane: no evidence surgical masks worn by surgical teams reduce wound infection in clean surgery	04/26/2016	NIH National Library of Medicine
32	CMAJ meta-analysis: N95s no better than surgical masks at protecting health workers from respiratory infection	05/17/2016	CMAJ Canadian Medical Association Journal
33	Source-control RCT: sick people wearing masks did not significantly reduce infections in household contacts	12/30/2016	National Library of Medicine
34	CDC-published review: 14 RCTs found no substantial effect of masks or hand hygiene on lab-confirmed flu transmission	05/01/2017	NIH National Library of Medicine
35	Cloth masks filtered only 39–65% of particles; performed worse against diesel exhaust	05/27/2017	NIH National Library of Medicine
36	Meta-analysis: masks protect healthcare workers, but RCT evidence for N95s over surgical masks is weak	08/07/2017	Clinical Infectious Diseases
37	Meta-analysis of pandemic flu studies: hand hygiene protective, but face masks showed no significant effect	09/01/2017	Epidemics
38	Surgical-mask nonwoven fabrics filter bacteria well but perform worse against smaller virus-sized aerosols	06/23/2018	NIH National Library of Medicine
39	JAMA RCT of 2,862 health workers: N95s and medical masks showed no difference in lab-confirmed flu (8.2% vs 7.2%)	09/03/2019	JAMA
40	PLOS Pathogens review of virus-bacteria interactions (note: not about masks)	02/11/2020	PLOS PATHOGENS
41	University of Iowa epidemiologist: no evidence masks protect healthy people; improper use raises infection risk	03/01/2020	Sacramento Bee
42	Turkish infectious-disease doctors: sweaty, misused N95 masks can themselves cause infections	03/15/2020	Anadolu Agency
43	Surgeon General Adams: 'the data doesn't show' public masking helps; improper use can increase infection risk	03/31/2020	Fox News
44	WHO, April 2020: no evidence healthy people wearing masks in the community prevents respiratory infection	04/07/2020	Business Insider
45	Wired argues masks lack clinical-trial proof but so do distancing and handwashing (note: article supports masking)	04/08/2020	Wired
46	Scoping review: evidence on reused, decontaminated or improvised facial protection for health workers is thin	05/05/2020	NIH National Library of Medicine
47	Two 14-year-old boys in China collapse and die within a week while running in gym class wearing masks	05/06/2020	New York Post
48	Singapore frontline health workers: most developed new headaches from N95s and protective eyewear	05/06/2020	NIH National Library of Medicine
49	Singapore study: only 13% of the public could put on an N95 mask correctly	05/20/2020	JAMA Network Open
50	NEJM: 'Wearing a mask outside health care facilities offers little, if any, protection from infection'	05/21/2020	New England Journal of Medicine
51	NEJM: catching Covid from a passing public interaction is minimal; masks outside hospitals offer little protection (same article as 9239/9427)	05/21/2020	The New England Journal of Medicine
52	NEJM authors: masks in hospitals are 'talismans' whose chief value is reducing anxiety, 'a marginally beneficial mask'	05/21/2020	New England Journal of Medicine
53	Compilation of pre-Covid evidence against public masking, with documented harms (Lockdown Sceptics)	06/07/2020	Lockdown Sceptics
54	Taiwan study: 81% of adults reused surgical masks several times a day, with contamination spread by handling	06/08/2020	Journal of Public Health Research
55	Norway's public health institute: 200,000 people would need to mask to prevent one infection a week; masks not recommended	06/10/2020	Norwegian Institute of Public Health
56	Chinese health workers in PPE: high rates of adverse skin reactions from prolonged N95 use	06/12/2020	Medicine (Baltimore)
57	Elastic mask loops may deform children's ear cartilage with prolonged daily use	06/18/2020	NIH National Library of Medicine
58	Hypothesis paper: exercising in masks may cause hypercapnic hypoxia and strain heart, lungs and immune system	06/22/2020	NIH National Library of Medicine
59	Physics of Fluids visualizations: bandanas and loose masks provide 'minimal stopping-capability' for small aerosols	06/30/2020	AIP Physics of Fluids
60	Umbrella review of 18 RCTs: community mask use did not reduce flu, confirmed viral infection or respiratory illness	07/01/2020	NIH National Library of Medicine
61	Dental-clinic modeling study of airborne pathogen transmission risk (note: not about mask efficacy)	07/02/2020	NIH National Library of Medicine
62	Surgical and N95 masks significantly reduced lung function and exercise capacity in healthy men	07/06/2020	Clinical Research in Cardiology
63	Oxford CEBM's Heneghan and Jefferson: a decade of mask trials shows poor compliance, no clear benefit, politics filling the gap	07/23/2020	The Centre for Evidence-Based Medicine
64	Child psychologist: mask mandates may impair young children's emotional and social development by hiding facial cues	07/23/2020	Wishtv.com8
65	Watts Up With That essay argues universal cloth masking does not reduce, and may increase, viral spread	07/25/2020	Watts Up With That?
66	Review of indoor humidity's role in airborne SARS-CoV-2 transmission (note: not about masks)	07/28/2020	Aerosol and Air Quality Research
67	Dermatologists link prolonged mask wear to candida (yeast) overgrowth around the mouth	08/04/2020	Everyday health
68	Dentists report 'mask mouth': decay, gum inflammation and bad breath in roughly half of patients	08/05/2020	New York Post
69	Danish, Dutch and Finnish health officials decline to recommend masks, citing little conclusive evidence they limit spread	08/06/2020	Foundation for Economic Education
70	Disability Rights California guidance on mask requirements and disability exemptions (note: supports masking)	08/13/2020	DRC Disability Rights California
71	Townhall: CDC's own 15-minute close-contact exposure rule applies with or without masks, so masks add little	09/14/2020	Townhall
72	Meta-review of 15 studies, 23,892 people: surgical masks in non-healthcare settings not significantly linked to fewer respiratory illnesses	09/20/2020	Frontiers in Medicine
73	CDC outpatient study: 85% of symptomatic Covid patients reported 'often' or 'always' wearing masks in prior two weeks	10/12/2020	Washington Examiner
74	Hajj cluster RCT of 7,687 pilgrims: face masks did not prevent lab-confirmed or clinical respiratory infection	10/13/2020	PLOS ONE
75	Lab study of masks made from sterilization wrap (note: evaluates an alternative material, not mask efficacy)	10/14/2020	NIH National Library of Medicine
76	AIER: media claims that high-mask states fare better ignore that those states were hit hardest before masking began	10/24/2020	American Institute for Economic Research
77	Danish RCT of 6,000 adults: recommending surgical masks did not significantly cut wearers' Covid infection rate	11/18/2020	Annals of Internal Medicine
78	DANMASK-19 full paper: mask recommendation did not reduce wearers' infection rate by more than 50% (same trial as 9233)	11/18/2020	NIH National Library of Medicine
79	2020 Cochrane review: medical masks make little or no difference to influenza-like illness or confirmed flu	11/20/2020	NIH National Library of Medicine
80	Tennessee county data: counties with mask mandates fared no better, and often worse, than counties without	11/24/2020	The Tennessee Star
81	County-level data show Florida and national mask mandates made no measurable difference in case rates	12/21/2020	Town Hall
82	Tennessee counties with mask mandates saw 4.7% of population infected vs. 4.6% in counties without	12/28/2020	Town Hall
83	Wisconsin high-school sports study: face mask use had no significant relationship with Covid incidence among athletes	02/18/2021	medRxiv (University of Wisconsin)
84	Montana cases rose 1,446% after mask mandate and fell 35% after it was lifted (Ian Miller charts via Tom Woods)	03/03/2021	Tom Woods
85	AIER: CDC's 10-state study crediting mask mandates for lower hospitalization growth rests on flawed comparison windows	03/04/2021	American Institute for Economic Research
86	Washington Post: states with stricter restrictions, including California, have not fared better than looser states like Florida	03/18/2021	The Washington Post
87	German review of 65 studies: masks cause measurable drops in oxygen, rises in CO2, headaches and 'mask-induced exhaustion syndrome'	04/20/2021	International Journal of Environmental Research and Public Health
88	CDC letter: 'not aware of any randomized controlled trials' showing masks, double masks or cloth coverings work against Covid	04/27/2021	CDC (via Twitter)
89	German registry of 25,930 children: 68% of parents report mask-related impairments including headache, irritability, poor concentration	04/28/2021	Research Square
90	Swiss Policy Research roundup: most studies find little or no evidence masks protect the general population	05/01/2021	Swiss Policy Research
91	US state analysis: case growth was independent of mask mandates, and mask use did not predict case growth (preprint v1)	05/18/2021	medRxiv
92	Indian blood-donor study links mandatory masking to intermittent hypoxia and rising hemoglobin levels	05/26/2021	Transfusion and Apheresis Science
93	JAMA Pediatrics letter: masked children inhaled elevated CO2, consistent with hypercapnia complaints (study later retracted)	06/30/2021	JAMA Pediatrics
94	National school dashboard: masking, closures and strict distancing associated with worse school outcomes (no excerpt)	07/21/2021	National COVID-19 School Response Dashboard
95	Physics of Fluids: aerosols escape and accumulate indoors despite masks; ventilation matters more than masks	07/21/2021	AIP Physics of Fluids
96	Pittsburgh pediatricians report language delays and social anxiety in toddlers from distancing and masking	08/11/2021	KDKA
97	Brown University preprint: children born during the pandemic show significantly lower verbal, motor and cognitive scores	08/11/2021	medRxiv (Brown University)
98	Forbes: school mask mandates and distancing inflict trauma-like stress on children, especially low-income	08/18/2021	Forbes
99	US state analysis: mask mandates did not slow Covid case growth at low or high community spread (preprint v2)	11/01/2021	medRxiv
100	Cato review: 14 of 16 RCTs found no significant benefit of masks over no masks; evidence 'of low quality'	11/08/2021	CATO Institute
101	Florida speech therapists report a 364% jump in baby and toddler referrals, blaming masks for speech delays	11/09/2021	WPBF
102	Cato: cloth mask evidence rests on observational and mechanistic studies; RCTs mostly fail to show benefit	12/15/2021	CATO Institute
103	UK government's own evidence summary admits its school face-covering analysis was not statistically significant	01/06/2022	UK Department for Education
104	UK government review: school mask evidence 'inconclusive,' not statistically significant; 94% of teachers say masks hurt communication	01/11/2022	BBC
105	CDC concedes, two years in, that loosely woven cloth masks worn by millions offer the least protection	01/14/2022	CNN (via CBS News Boston)
106	Fargo natural experiment: neighboring school districts with and without mask mandates had identical student case rates	07/01/2022	Research Square
107	Catalonia study of 599,314 kids: masked 6-year-olds saw no less Covid than unmasked 5-year-olds	08/23/2022	Archives of Disease in Childhood (BMJ)
108	Re-analysis finds Bangladesh mask trial's effect matched by staff-caused population imbalance, not masks	09/15/2022	NIH National Library of Medicine
109	Replicating CDC's school-mask study with seven times more data, researchers find the mask-mandate effect disappears	09/30/2022	NIH National Library of Medicine
110	Annals RCT of health workers: medical masks and N95s gave similar Covid protection; ~10% reported adverse reactions	11/29/2022	Annals of Internal Medicine
111	UK Department for Education: two-thirds of pupils say masks made communicating with teachers difficult	11/30/2022	UK Department for Education
112	Cochrane review of 78 RCTs: community mask wearing probably makes little or no difference to Covid/flu spread	01/30/2023	Cochrane Database of Systematic Reviews
113	NYT columnist Bret Stephens: Cochrane review shows 'mask mandates were a bust'; skeptics were right	02/21/2023	The New York Times
114	Finnish study: extending school mask mandates to 10–12-year-olds produced no extra drop in Covid cases	04/21/2023	BMC Public Health
115	Fauci to NYT Magazine: at the population level, masks work 'at the margins—maybe 10 percent'	04/28/2023	Newsweek
116	Re-analysis of Boston school mask study finds no consistent link between mask mandates and student Covid cases	07/22/2023	arXiv
117	Fauci concedes on CNN the data for masks' effect on the pandemic 'as a whole' are 'less strong'	09/03/2023	Fox News
118	Cochrane mask review authors: editor's statement 'undermined' their findings; review never retracted or changed	09/15/2023	The Daily Sceptic (Heneghan & Jefferson)
119	Systematic review: no RCTs support masking kids; 16 observational studies found no link to infection	12/05/2023	Archives of Disease in Childhood (BMJ)