121 References to Scientific Studies on Facemask Effectiveness

We have provided the following information to assist you in your research so you can make a fully informed decision on the matter of wearing facemask.  We cannot yet find any independent peer-reviewed studies without any conflict of interest to support the idea that wearing a facemask outside a medical or dusty setting will do anyhting to improve your health or the health of others. 

We recommend you take the time to educate yourself as much as possible by reading as many of the following links as you can.  This extensive list has been collected over time, some links may no longer be valid.  Please report invalid links so we can correct them.

1. Mask mandate and use efficacy in state-level COVID-19 containment
“We did not observe associaGon between mask mandates or use and reduced COVID-19
spread in US states.”  https://www.medrxiv.org/content/10.1101/2021.05.18.21257385v2
2. Masks for prevention of viral respiratory infections among health care workers
and the public: PEER umbrella systematic review
A 29 study meta-analysis review that included 11 studies and 18 random control trials of 26,444
participants. This systematic review found limited evidence that the use of masks might
reduce the risk of viral respiratory infections.
3. 16 Studies: Effectiveness of personal protec4ve measures in reducing pandemic influenza
This meta-analyses concluded that regular hand hygiene provided a significant protecGve
effect, and face mask use provided a non-significant protecGve effect.
4. Study: Experimental investigation of indoor aerosol dispersion and accumula4on in the
context of COVID-19: Effects of masks and ventilation
This study published by the American Institute of Physics found that face masks reduced
indoor aerosols by 12% at most — which is not enough to prevent infections.
5. Study: Non-pharmaceu4cal Measures for Pandemic Influenza in Non-healthcare SePngs-
Personal Protec4ve and Environmental Measures
The use of face masks, either by infected or non-infected persons, does not have a
significant effect on influenza transmission.

6. Study: Physical interventions to interrupt or reduce the spread of respiratory viruses
“There is moderate certainty evidence that wearing a mask makes li;le or no difference to
the outcome of laboratory-confirmed influenza compared to not wearing a mask.”

7. Study: An Overview on the Role of Rela4ve Humidity in Airborne Transmission of SARS-
CoV-2 in Indoor Environment
RelaGve Humidity (RH) is an important factor responsible for airborne transmission of SARS-
CoV-2 virus. In dry indoor areas, chances of airborne transmission are higher than humid
areas. Indoor air at 40 to 60 percent RH is the opGmum level for human health. Important
to set minimum RH standard for indoor environments.

8. 29 Studies: Effectiveness of Masks and Respirators Against Respiratory Infec4ons in
Healthcare Workers
This meta-analysis concluded that evidence of a protecGve effect of masks or respirators
against verified respiratory infecGon was not staGsGcally significant.

9. Study: “Exercise with face mask; Are we handling a devil’s sword?” – A physiological
There is no evidence to suggest that wearing a mask during exercise offers any benefit from
the droplet transfer from the virus. [This is noteworthy, as the argument is that although
masks can not filter out the SARS-CoV-2 virus, that they may be able to filter out droplets
that carry the SARS-CoV-2 virus. This study seems to say no.]

10. Study: A cluster randomized trial of cloth masks compared with medical masks in
healthcare workers
Penetration of cloth masks by influenza particles was almost 97 percent and medical masks
44 percent — so cloth masks are essentially useless, and “medical grade” masks don’t
provide adequate protection. This study is the first RCT of cloth masks, and the results
caution against the use of cloth masks.
[Note: influenza particles are over three times the size of the SARS-CoV-2 virus (see here),
so it can be inferred that the filter efficiency for the SARS-CoV-2 virus would be worse.]

11. Study: Surgical face masks in modern operating rooms – a costly and unnecessary ritual?
The wearing of face masks by non-scrubbed staff working in an operating room with forced
ventilation seems to be unnecessary. [An argument from mask proponents is that wearing a
mask protects others from you. This study seems to say no.]

12. Study: Face mask against viral respiratory infections among Hajj pilgrims
A large randomized controlled trial with 8000± participants, found that face masks “did not
seem to be effecGve against laboratory-confirmed viral respiratory infections nor against
clinical respiratory infection.”

13. Study: Simple respiratory protection–evaluation of the filtration performance of cloth
masks and common fabric materials against 20-1000 nm size particles
“Results obtained in the study show that common fabric materials may provide marginal
protecGon against nanoparGcles, including those in the size ranges of virus-containing
parGcles in exhaled breath.” [SARS-CoV-2 virus is about .1 micron = 100 nm]

14. Study: Respiratory performance offered by N95 respirators and surgical masks: human
subject evalua4on with NaCl aerosol represen4ng bacterial and viral par4cle size range
“The study indicates that N95 filtering face piece respirators may not achieve the expected
protecGon level against bacteria and viruses.”

15. Study: Analysis of the Effects of COVID-19 Mask Mandates on Hospital Resource
Consump4on and Mortality at the County Level
There was no reducGon in per-populaGon daily mortality, hospital bed, ICU bed, or
venGlator occupancy of COVID-19-posiGve paGents a;ributable to the implementaGon of a
mask-wearing mandate.

16. Study: Modeling of the Transmission of Coronaviruses, etc. in Dental Clinics
The evidence suggests that transmission probability is strongly driven by indoor air quality
— specifically venGlaGon — and the least by respiratory protecGon via mask use.

17. 16 Studies: Evidence for Community Cloth Face Masking to Limit the Spread of SARS-
CoV-2: A Critical Review
This review looked at the quality of the studies supporting masking. “Of sixteen meta-
analyses, eight were equivocal or critical as to whether evidence supports a public
recommendaGon of masks, and the remaining supported a public mask intervention on
limited evidence, primarily on the basis of the precautionary principle.”

18. Study: Aerosol penetra4on and leakage characteris4cs of masks used in the health care
“We conclude that the protecGon provided by surgical masks may be insufficient in
environments containing potenGally hazardous sub-micrometer sized aerosols.” [Note: the
SARS-CoV-2 virus is a sub-micrometer sized parGcle.]

19. 3 Studies: Disposable surgical face masks for preven4ng surgical wound infec4on in clean
“We included three trials, involving a total of 2106 parGcipants. There was no staGsGcally
significant difference in infecGon rates between the masked and unmasked group in any of
the trials.”

20. 2 Studies: Disposable surgical face masks: a systema4c review
“Two randomized controlled trials were included involving a total of 1453 paGents. …in a
large trial there was no difference in infecGon rates between the masked and unmasked

21. Study: Face seal leakage of half masks and surgical masks
“The filtraGon efficiency of the filter materials was good, over 95%, for parGcles above 5
micron in diameter but great variaGon existed for smaller parGcles.” Coronavirus is .1±
microns, therefore these masks would not offer good protecGon from that virus.

22. Study: Comparison of the Filter Efficiency of Medical Non-woven Fabrics against Three
Different Microbe Aerosols
“The filter efficiencies against influenza virus parGcles were the lowest.”
[Note: influenza parGcles are over three Gmes the size of the SARS-CoV-2 virus (see here),
so it can be inferred that the filter efficiency for the SARS-CoV-2 virus would be worse.]

23. Study: Aerosol penetration through surgical masks
“Although surgical mask media may be adequate to remove bacteria exhaled or expelled by
health care workers, they may not be sufficient to remove the sub-micrometer size aerosols
containing pathogens.” [The SARS-CoV-2 virus is sub-micrometer.]

24. 6 Studies: Effectiveness of N95 respirators versus surgical masks against influenza: A
systema4c review and meta-analysis
This meta-analysis was of six Randomized Controlled Trials (RCTs) involving 9,171
parGcipants. The conclusion: “the use of N95 respirators compared with surgical masks is
not associated with a lower risk of laboratory- confirmed influenza. It suggests that N95
respirators should not be recommended for the general public.”

25. Study: N95 Respirators vs Medical Masks for Preven4ng Influenza Among Health Care
Personnel: A Randomized Clinical Trial
“2371 parGcipants completed the study and accounted for 5180 HCW-seasons. … Among
outpaGent health care personnel, N95 respirators vs medical masks as worn by parGcipants
resulted in no significant difference in the incidence of laboratory-confirmed influenza.”

26. Commentary: Universal Masking in Hospitals in the COVID-19 Era
An article in the New England Journal of Medicine (wri;en by five physicians) came to the
conclusion that face masks offer li;le to no protecGon in everyday life.

27. Study: Masking lack of evidence with politics
“It would appear that despite two decades of pandemic preparedness, there is considerable
uncertainty as to the value of wearing masks.”

28. 12 Studies: Face masks to prevent transmission of influenza virus: a systematic review
In this meta-analysis of twelve studies, the authors found li;le data to support the use of
face masks to prevent wearers from becoming infected.

29. Study: Use of surgical face masks to reduce the incidence of the common cold among
health care workers in Japan: a randomized controlled trial
Face mask use in healthcare workers has not been demonstrated to provide benefit in
terms of colds symptoms or geqng colds.

30. Study: Effectiveness of Adding a Mask Recommenda4on to Other Public Health Measures
to Prevent SARS- CoV-2 Infec4on in Danish Mask Wearers
The COVID-19 infection results between mask wearers and the control group were not
statistically significant.

31. CDC: “CDC is not aware of any randomized controlled trials that show that masks, or
double masks, or cloth face coverings are effective against COVID-19.”

32. Study: Testing the efficacy of homemade masks: would they protect in an influenza
“Our findings suggest that a homemade mask should only be considered as a last resort to
prevent droplet transmission from infected individuals.” [Note that droplets are significantly
larger than the SARS-CoV-2 virus.]

33. Study: Evaluating the efficacy of cloth face masks in reducing particulate mader exposure
“Our results suggest that cloth masks are only marginally beneficial in protecting individuals
from particles <2.5 micron.” [Coronavirus is .1± micron.]

34. Study: Assessment of Proficiency of Mask Donning Among the General Public in
The survey was administered to 2499 adults, who were given instrucGons for proper mask
use. Subsequently, only 12.6% passed the Visual Mask Fit (VMF) test. This would indicate
that the compliance of children would be lower yet.

35. 17 Studies: The use of masks and respirators to prevent transmission of influenza: a
systema4c review of the scien4fic evidence
Seventeen studies were reviewed in this meta-analysis. “None of the studies we reviewed
established a conclusive relaGonship between mask ⁄ respirator use and protecGon against
influenza infecGon.”
[Note: influenza parGcles are over three Gmes the size of the SARS-CoV-2 virus (see here),
so it can be inferred that the filter efficiency for the SARS-CoV-2 virus would be worse.]

36. Study: Facial protection for healthcare workers during pandemics: a scoping review
This study used 5462 peer-reviewed arGcles and 41 grey literature records. Conclusion:
“The COVID-19 pandemic has led to criGcal shortages of medical-grade PPE. AlternaGve
forms of facial protecGon offer inferior protecGon.”

37. Study: Particle removal from air by face masks made from Sterilization Wraps:
Effectiveness and Reusability
“We found that 60 GSM face mask had particle capture efficiency of 94% for total particles
greater than 0.3 microns.” [These are be;er quality masks than standard cloth masks, so
cloth masks would provide li;le effectiveness for the .1 micron SARS-CoV-2 virus.]

38. Study: Visualizing the effec4veness of face masks in obstruc4ng respiratory jets
A few studies have considered the filtraGon efficiency of homemade masks made with
different types of fabric; however, there is no broad consensus regarding their effecGveness
in minimizing disease transmission.


A Further 83 Compelling References

We have provided the following information to assist you in your research.

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3 P Murtagh, V Giubergia, et al. Lower respiratory infections by adenovirus in children. Clinical features and ris factors for bronchiolitis obliterans and mortality. Ped Pulm. 44. 450-456. https://doi.org/10.1002/ppul.20984 https://www.nature.com/articles/s41598-018-32008-x#ref-CR10

4 N Nin, A Muriel et al. Severe hypercapnia and outcome of mechanically ventilated patients with moderate or severe acute respiratory distress syndrome. Int Care Med 43. 200-208. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5630225/

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6 B Chandrasekaran, S Fernandes. Exercise with facemask; Are we handling a devil’s sword? – A physiological hypothesis. Nov 2020. 144 (110002). doi: 10.1016/j.mehy.2020.110002 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7306735/#b0135


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12 Carbon Dioxide Health Hazard Information Sheet. Food Safety Inspection Service, US Department of Agriculture.

https://www.fsis.usda.gov/wps/wcm/connect/bf97edac-77be-4442-aea4-9d2615f376e0/Carbon- Dioxide.pdf?MOD=AJPERES

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