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Covid-19 spread via droplet distance

(Source: "California Covid-19 Response Kit" )

Video: Graphic modeling of how micro-droplets carrying Covid-19 virus can remain in the air for some time. (Source: NHK-World Japan.) 

How wearing face masks reduce risk of infection

(Source: "Frequently Asked Questions about Cloth Face Coverings" by City of Santa Monica. Contagion defined.)