"Talking less, more quietly, or not at all limits the manufacture of both large droplets and aerosols. ... compared with yelling, quiet talking reduces aerosols by a factor of five; being completely silent reduces them by a factor of about 50. That means talking quietly, rather than yelling, reduces the risk of viral transmission by a degree comparable to properly wearing a mask.

“The truth is that if everybody stopped talking for a month or two, the pandemic would probably die off,” Jimenez said. ... 


...  Donald K. Milton, a professor at the University of Maryland School of Public Health, who has studied how surgical face masks can reduce viral spread, told me in an email that “silence and quiet speaking are reasonable means of intervening” to reduce COVID-19 transmission.

One of the more curious international success stories of the pandemic is Japan. While much of the world emphasized the importance of testing and tracing, Japan initially had no mass testing and no sophisticated means of contract tracing. Yet, adjusted for population, the country currently has approximately 98 percent fewer COVID-19 deaths than the United States. Much credit has gone to its crystal-clear public guidance to avoid the three C’s: closed spaces, crowded places, and close-contact settings, including “close-range conversations.”

That third C deserves more amplification. Even after its transit ridership bounced back to normal, Japan reported no outbreaks on Tokyo’s famously crowded subways. The city’s trains are typically well ventilated, and Japanese people have had decades of practice wearing masks. But something else is at work here: Japanese commuters have an informal rule to avoid talking loudly on trains, if at all.

So while New York City spends $15 million a month blasting its subways with antimicrobial sprays, the Japanese keep their trains safe with a cheaper tactic: masking up and shutting up."