Originally Posted by anacapamalibu

According to experts there has been believed transmission of the virus during the incubation period in which the infected was asymptomatic. If true wearing a mask in any circumstance could be considered wearing it to protect others.

As far as surgical masks, FDA guidelines
"Surgical masks are not intended to be used more than once. If your mask is damaged or soiled, or if breathing through the mask becomes difficult, you should remove the face mask, discard it safely, and replace it with a new one. To safely discard your mask, place it in a plastic bag and put it in the trash. Wash your hands after handling the used mask."

https://www.fda.gov/medical-devices/...sks-face-masks

We are reporting a case of 2019-nCoV infection acquired outside Asia in which transmission appears to have occurred during the incubation period in the index patient.
The fact that asymptomatic persons are potential sources of 2019-nCoV infection may warrant a reassessment of transmission dynamics of the current outbreak.

https://www.nejm.org/doi/full/10.1056/NEJMc2001468


"The incubation period for a virus is the time between catching the virus and showing symptoms of disease. For thenovel coronavirus SARS-CoV-2, health officials estimate an incubation period of between one and 14 days.
Most people start showing symptoms about five days after becoming infected,"

https://www.livescience.com/coronavi...ms-appear.html