"a virus is very very small (0.1 micron) and able to get through and around any mask to..."
A primary route of transmission of COVID-19 is via respiratory particles, and it is known to be transmissible from presymptomatic, paucisymptomatic, and asymptomatic people
Because we don't know who is in position to transmit the virus and many respiratory particles become smaller due to evaporation, it makes sense to impose public mask wearing so that those potentially infected particles stay confined withing the mask.
This is a case, so I think, where the public good or public interest must override personal choice or freedom.
