"Normal, quiet breathing releases aerosol droplets that can suspend in the air for a short period of time, said David Vlahov, an epidemiologist at Yale University’s School of Nursing. Some of those droplets might contain coronavirus germs.
But more of those aerosol droplets spew forth from your mouth through loud speech. Those droplets can linger in the air for up to 14 minutes, Vlahov said. So the less spewing you do, the safer it is for everyone else. That’s why Vlahov believes the MTA should do more to persuade people not to talk on buses and trains.
“Discouraging talking on public transportation is a reasonable and prudent strategy to put in place,” Vlahov told the Daily News. It’s not a message the MTA is loudly promoting to the 2.8 million people who are back riding buses and trains on an average weekday.
MTA officials have considered adding “No Talking” signs on trains. But so far, the agency has not been willing to take that extra step."
news.yahoo.com/no-talking-signs-nyc-subway-222600015.html