>For interest wrt cloth masks: authorities identify only one reliable study looking at effect of cloth masks on respiratory viral infection, from 2015. Here it is: https://bmjopen.bmj.com/content/5/4/e006577
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>This study compared efficacy of medical vs cloth masks by healthcare workers, compared to a control group following standard practice on the wards. Quoting, with my emphasis:
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>Results: The rates of all infection outcomes were highest in the cloth mask arm, with the rate of ILI statistically significantly higher in the cloth mask arm (relative risk (RR)=13.00, 95% CI 1.69 to 100.07) compared with the medical mask arm. Cloth masks also had significantly higher rates of ILI compared with the control arm. ... Penetration of cloth masks by particles was almost 97% and medical masks 44%.
>Conclusions: This study is the first RCT of cloth masks, and the results caution against the use of cloth masks. This is an important finding to inform occupational health and safety. Moisture retention, reuse of cloth masks and poor filtration may result in increased risk of infection. Further research is needed to inform the widespread use of cloth masks globally. However, as a precautionary measure, cloth masks should not be recommended for HCWs, particularly in high-risk situations, and guidelines need to be updated.
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>Compare with the same authors' contribution to the CDC journal this week: https://wwwnc.cdc.gov/eid/article/26/10/20-0948_article
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>The gist is that cloth masks may be better than nothing if there's no alternative (which is not what their 2015 paper found) but their current advice is:
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> The general public should be educated about mask use because cloth masks may give users a false sense of protection because of their limited protection against acquiring infection). Correctly putting on and taking off cloth masks improves protection... Taking a mask off is a high-risk process because pathogens may be present on the outer surface of the mask and may result in self-contamination during removal.
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>Armed with this knowledge, notice how mask wearers tend to touch or adjust their masks or pull them down off their noses and definitely don't take them off in the approved fashion to reduce infection risk.
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>To reduce risk for UTers, here's the official advice for putting on a cloth mask: it ALWAYS starts with hand hygiene:
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>- Wash your hands with soap and water or alcohol-based hand sanitizers.

>-Take a clean and dry cloth mask. Place and hold the mask over your nose and mouth. Tie upper strings first at the back of your head and then the lower set at the base of your neck. If cloth mask has loops, hold the mask over your nose and mouth and tie ear loops.
 If mask has pleats, unfold the mask from top and bottom so it covers your nose, mouth, and chin. Do not touch the outer layer of face masks during use.
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>Imagine yourself putting on a cloth mask without touching the outside of it. It involves a dexterous effort that nobody will perform unless told why.
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>Taking the cloth mask off:
>-Wash your hands

>- Do not touch the outer surface of the face mask while removing.

>- Untie the lower strings first and then upper strings. In case of ear loops, remove ear loops first and then remove the mask.
>- Place the mask in a plastic zipper-sealed bag until it can be decontaminated.
>- Wash your hands again after removing the mask.
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>This means that every time you take the mask off it has to go in a plastic bag until washed, and you only ever put on a newly washed mask.
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>I'd say these instructions are rarely if ever followed in the community, or by reporters who act as if a mask is an automatic service to humanity rather than increasing the risk if you're not doing it right.
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>IMHO CDC needs to recruit pop stars or Fauci or even Trump to show people how to use a mask properly, if you're going to wear one. IMHO the population is more than capable of understanding that if you need to paw at or adjust the mask or not apply it properly, you are increasing the risk, not decreasing it. That would be the scientific response.

I carry a mask with me and sometimes wear it - not because I think it does any good but it seems to make some people feel safe. I remember when I first went into the Army and we practiced donning our "protective mask" for hour after hour. After a few years I was sent to the Chemical, Biological and Radiological Warfare School. There I learned that the mask worked fairly well against the gases used in WW1- but nobody used them any more. Everyone had switched to V-series gases like sarin. If you were attacked with V-series gases you would probably absorb enough gas thru the skin to kill you in 1-10 minutes. They now have MOPP or PPE now that protects the whole body but for at least 30 years we just had a "security blanket". Do you remember the "Duck, Roll, and Cover" exercises the school kids used to practice? The military had one more step " kiss your ass good-by".