A curation of information for the AAPS (Association of American Physicians and Surgeons)
by Marilyn Singleton, MD, JD
WHO, CDC, NIH now recommend cloth face coverings where social distance is hard to do, i.e., grocery stores. This recommendation was made without a single scientific paper or other information provided to support that cloth masks actually provide any respiratory protection.
The theory for wearing masks is:
- Source control: to trap droplets that come out of a person’s mouth when they cough or sneeze (CF: or even breathe or talk vigorously)
- Personal protection: Personal Protective Equipment (PPE)–only N95 masks are considered PPE
Important to note:
COVID-19 particle .125 microns
Influenza Virus .08 – .12 microns
Human hair 150 microns (1200x the COVID-19 particle)
Larger respiratory droplets (>5 microns) remain in the air for a short time and travel only short distances, generally < 1 meter, and fall to the ground quickly—this is the basis for 6 ft of social distancing.
Small aerosolized droplets (<5 microns) can remain in the air for at least 3 hours and travel long distances (up to 27 ft)
Air currents matter:
- In an air conditioned environment the large droplets may travel farther.
- Ventilation. Good ventilation can dilute the number of small droplets to one half after 30 seconds. Poorly ventilated and populated places (public transport and nursing homes) have high COVID-19 disease transmission despite physical distancing.
- Greater humidity inactivates droplets; dryness drives the small aerosol particles
The preponderance of scientific evidence supports that aerosols play a critical role in the transmission of COVID-19. Years of dose response studies indicate that if anything gets through, you will become infected.
- Any respiratory protection respirator or mask must provide a high level of filtration and fit to be highly effective in preventing the transmission of COVID-19.
- Public health officials define a significant exposure to COVID-19 as: face to face contact within 6 feet with a patient with symptomatic COVID-19 that is sustained for a least a few minutes (and some say more than 10 minutes or even 30 minutes).
- The chance of catching COVID-19 from a passing interaction in a public space is therefore minimal.
Masks: Filter, Efficiency and Fit
Surgical masks are loose-fitting devices that were designed to be worn by medical personnel to protect accidental contamination of patient wounds, and to protect the wearer against splashes or sprays of bodily fluids. The aren’t effective at blocking particles smaller than 100 microns. (CF: C19 aerosolized particles are .125 microns, one eight hundredth the size of mask effectiveness)
From OSHA/CDC: “A surgical mask is not a respirator. It cannot be used to protect workers who perform or assist with aerosol-generating procedures, which may create very fine aerosol sprays. A surgical mask can only be used to protect workers from contact with the large droplets made by patients when they cough, sneeze, talk or breathe.”
- Wearing masks (other than N95) will not be effective at preventing COVID-19 transmission, whether worn as source control or as PPE.
- Surgical masks are better than cloth but not very efficient at preventing emission from infected patients.
Studies noted from around the world with links. Below are comments or conclusions from various studies.
Percentage of penetration of COVID-19 particles:
Cloth masks 97%
Medical masks 44%
N95 masks .01%
Cloth masks resulted in significantly higher rates of infection than medical masks, and also performed worse than the control arm who wore nothing.
2017 Singapore Study
- Compared to masks, N95 respirators conferred superior protection against clinical respiratory illness and laboratory-confirmed bacterial, but no viral infections or influenza life illness.
- Evidence of protective effect of masks or respirators against verified respiratory infection was not statistically significant (compared to no mask)
CDC Review, May 2020
- There is limited evidence for face masks’ effectiveness in preventing laboratory-confirmed influenza virus transmission either when worn by the infected persons for source control or when worn by uninfected persons to reduce exposure.
From an August 2020 study in advances.sciencemag.org
- Neck fleece and bandanas seemed to make transmission worse, as they seemed to disperse the largest droplets into a multitude of smaller droplets
From Austrian observation, August 2020
- The introduction, retraction and re-introduction of mandatory face masks in Austria had no influence at all on the infection rate.
- The reuse of cloth masks, frequency and effectiveness of cleaning and poor filtration may result in increased risk of infection.
Conclusions from Organizations:
WHO, April 2020
- ”The wide use of masks by healthy people in the community setting is not supported by current evidence and carriers uncertainties and critical risks.”
WHO, June 2020
- The WHO has changed its stance on wearing face masks during the COVID-19 pandemic. People over 60 and people with underlying medical conditions should wear a medical-grade mask when they’re in public and cannot socially distance…The use of a mask alone is insufficient to provide an adequate level of protection or source control…The reasons for recommending masks has little to do with effectiveness.
CDC, August 2020
- Masks are recommended…
- “We know that wearing a mask outside health care facilities offers little, if any, protection from infection. Public health authorities define a significant exposure to COVID-19 as face-to-face contact within 6 feet with a patient with symptomatic COVID-19 that is sustained for at least a few minutes…The chance of catching COVID-19 from passing interaction in a public space is therefore minimal. In many cases, the desire for widespread masking is a reflexive reaction to anxiety over the pandemic.” It is also clear that masks serve symbolic roles. Masks are not only tools, they are also talismans that may increase health care workers’ perceived sense of safety, well-being, and trust in their hospitals. Although such reactions may not be strictly logical, we are all subject to fear and anxiety, especially during times of crisis. One might argue that fear and anxiety are better countered with data and education than with a marginally beneficial mask.”
Objects and Surfaces:
- The CDC’s most recent statement regarding contracting COVID-19 by touching a surfaces: “Based on the data from lab studies on COVID-19 and what we know about similar respiratory diseases, it may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth nose of possibly their eyes…but this isn’t thought to be the main way the virus spreads.”