There is such piece of the dialog between journalist and the doctor (in the middle of an interview about Coronavirus):
-If somebody's coughing on the bus should you get off?
-No, getting off isn't gonna help.
There are three possibilities when someone is coughing on the bus:
While on the bus, do not touch your face. When you get off the bus, sanitize your hands or wash them with soap and water if you can. Now it no longer matters whether droplets landed on you.
Notice that the CDC advice doesn't say "if you find yourself near someone coughing, get away from them as soon as you can." Doing so is either unnecessary (first two bullets) or won't help (last bullet - it's too late, but handwashing will save you anyway.)