In this case, aerosol means it is contained on tiny droplets of mucus or saliva. It doesn’t mean a pure virus.
https://en.wikipedia.org/wiki/Aerosol
An aerosol (abbreviation of "aero-solution") is a suspension of fine solid particles or liquid droplets in air or another gas.[1] Aerosols can be natural or anthropogenic. Examples of natural aerosols are fog, mist, dust, forest exudates and geyser steam. Examples of anthropogenic aerosols are particulate air pollutants and smoke.[dubious – discuss][1] The liquid or solid particles have diameters typically less than 1 um
None of the masks can filter out 1 um particles or 1 um liquid droplets.