For the record:
These protect others (such as patients) from most airborne infections from the wearer. That's why they wear them in surgery, to reduce the risk to patients from airborne contaminants from the surgical team.
These look like masks but are soft shelled form fitting appliances. These are designed to protect the wearer (for a limited time) from airborne pollutants and in some cases, airborne biohazards susceptible to the filtration specs of the respirator.
USA CDC COMMENTS
The US CDC makes up rules for US society but they're not necessarily applicable to other nations. Asia and specifically China has a population density of about 146 people/km2 while the USA has a population density of about 35/km2. Higher population density means higher risk of exposure. Think one person in the room (USA) vs FIVE people in the same room (China). The CDC comments were specifically designed to prevent a run on critical hospital supplies as frequently happens in china. Remember the iodized salt run several years ago when Japan had its first nuclear power plant meltdown?
So I personally agree and support Colin's appeal to continue to wear face masks or respirators in public - both for personal safety, public safety, and probably most importantly - for the optics, until the quarantines can complete their task of effectively containing and suppressing this pandemic and any attempts at resurgence.