Whether an aerosol hits your face, or you breathe air with suspended particles containing the virus, the virus has several challenges it needs to overcome (described in the link above). Its success is not guaranteed. An increase in virus particles improves its chance while a decrease improves your chance.
In theory, a single virus particle could achieve its goal.
A virus has to achieve viral entry: it has to find a suitable host cell, and introduce its viral material.
https://en.wikipedia.org/wiki/Viral_entry
Whether an aerosol hits your face, or you breathe air with suspended particles containing the virus, the virus has several challenges it needs to overcome (described in the link above). Its success is not guaranteed. An increase in virus particles improves its chance while a decrease improves your chance.
In theory, a single virus particle could achieve its goal.