Role of masks for COVID prevention outside of hosptial use

The following is my opnion and not a medical recommendation.

 Public face mask use appears to be common in Asian countries and also is now required in 

the Czeck Republic where people wear masks as a civil duty with the  shared realization that "I protect you by wearing a mask and you protect me by wearing a mask."

Corona virus is spread by droplets by infected persons even if they are asymptomatic and both simple surgical type face masks and the more expensive and protective N 95 masks can significantly reduce spread of coronavirus.

Both type of masks have been scarce in the US as Covid 19 cases exploded. Expectations and then realization of actual mask shortages in medical care facilities lead public health officials to discourage the public from using masks in the hope that more would be available for health care workers

Sometimes it has been argued that the masks were not effective when used by the public while at the same time saying that the masks should be reserved for medical personnel use in whose hands they would somehow offer important protection to them. Of course, protection is not a function of one's profession.

It is likely that it was believed that  officially recommending masks would lead to a large public demand  , making it even more difficult for health facilities to obtain masks.

As Covid  19 cases continue to increase and the mask shortage worsened, the CDC  said that masks can be reused and ,that homemade masks and scarfs could be used as a last resort by health care workers. This was a major change in CDC recommendations.Home made masks and scarfs can be used to protect the public as well, although that was not said by CDC.

Jeremy Howard,a Deep Learning specialist from Stanford, has posted an excellent review of the use and value of face masks by the general public to decrease COVID spread and describes widespread use by the public in many countries.See here

https://www.youtube.com/results?search_query=jeremy+howard

He gives links to sites with important information on how to clean masks and how to make masks at home from towels, t shirts etc. Some may worry about being accused of taking masks away from doctors and nurses if they wear a mask in public. Home made masks hopefully defuse  that issue.

Summary:
Covid 19  is spread by droplets by asymptomatic as well as symptomatic persons
Various kinds of masks decrease risk of spread
Masks can be made at home and worn in public  without shame .A great DIY project
Masks  protect others perhaps even more than they protect the wearer
It has been suggested that it would be unpatriotic for the public to wear masks.I suggest the opposite.
wearing masks is patriotic.An asymptomatic covid 19  infected person being in public exposing others to the disease is certainly not patriotic.
I am not recommending  to bid up prices of masks,No one wants to take masks away from HCWs.
 But if you already have masks on hand ,wear them .If not they really can be made at home and will offer some important protection . Yes, less than the properly fitted and correctly worn N 95 and less than surgical masks but significant protection nevertheless.
Bottom line wear masks in crowds (including grocery shoping)

Finally, imagine for a moment if only 25% of subway riders in New York (8 million riders per day) wore masks for the last 2 -3 weeks what the results might have been. Also imagine the potential benefit after we all come out emerge from sheltering in place how potentially important wide spread use of mask might be in decreasing the risk and/or impact of a second wave.

The following quote is from Scott Alexander writing on his blog slatestarcodex.com on 3/23/20 giving a detailed analysis on the research of various masks and the protection they provide;

". So should you wear a mask?

Please don’t buy up masks while there is a shortage and healthcare workers don’t have enough.

If the shortage ends, and wearing a mask is cost-free, I agree with the guidelines from China, Hong Kong, and Japan – consider wearing a mask in high-risk situations like subways or crowded buildings. Wearing masks will not make you invincible, and if you risk compensate even a little it might do more harm than good. Realistically you should be avoiding high-risk situations like subways and crowded buildings as much as you possibly can. But if you have to go in them, yes, most likely a mask will help.

In low-risk situations, like being at home or taking a walk, I mean sure, a mask might make you 0.0001% (or whatever) less likely to get infected. If that’s worth it to you, consider the possibility that you might be freaking out a little too much about this whole pandemic thing. If it’s still worth it, go for it.

You are unlikely to be able to figure out how to use an N95 respirator correctly. I’m not saying it’s impossible, if you try really hard, but assume you’re going to fail unless you have some reason to think otherwise. The most likely outcome is that you have an overpriced surgical mask that might make you incorrectly risk-compensate.

If you are a surgeon performing surgery, bad news. It turns out surgical masks are not very useful for you (1, 2)! You should avoid buying them, since doing so may deplete the number available for people who want to wear them on the subway."

Here is a quote from a blog post by Tomas Pueyo entitled "Coronovirus:The Hammer and the Dance"which has attracted considerable interest.Here is the link.https://medium.com/@tomaspueyo/coronavirus-the-hammer-and-the-dance-be9337092b56

Pueyo considers masks part of the solution." (my bolding)

"the massive impact of policies like those of Singapore or South Korea:

• If people are massively tested, they can be identified even before they have symptoms. Quarantined, they can’t spread anything.
• If people are trained to identify their symptoms earlier, they reduce the number of days in blue, and hence their overall contagiousness
• If people are isolated as soon as they have symptoms, the contagions from the orange phase disappear.
• If people are educated about personal distance, mask-wearing, washing hands or disinfecting spaces, they spread less virus throughout the entire period."

(note the blue and orange wording references refer to charts in his article)

Maybe it is this simple: If asymptomatic patients are not contagious, the masks only for the symptomatic rule works, but if the  asymptomatic are contagious that rule does not work.

addendum: 4/11/20 Several glaring typos finally corrected. Also now the CDC has blessed the wearing of face masks by the general public, preferably of the home made variety.Two days ago at the grocery about 50% of the shoppers wore masks, most not of the DIY type.

Addendum 5/8/20 Today at Krogers only 2 of the approximately 40-50 person did not have masks.All of the store workers did and now they have erected plexiglass barriers shielding the checkers.