For the general public masks offer a generic protection to the one wearing the mask, but more importantly to those around, if the bearer is unknowingly infected.
For this level of protection and considering a limited use of the mask (one hour or less), then it makes sense to extend its use adopting some simple procedures.
The mask may be contaminated and thus must be properly handled when removing, storing, wearing again in case of reuse.
But more importantly masks can be sanitised exposing them for 30 minutes to dry air at 70 degrees. This can be easily achieved in a ventilated oven, at home. More suggestions are available here