Before revision:  In response to the novel coronavirus SARS-CoV-2 epidemic, which has become a major public health issue worldwide, we provide a didactic overview of airborne germ transmission as seen from a physics perspective  .
After revision:  In response to the novel coronavirus SARS-CoV-2 epidemic, which has become a major public health issue worldwide, we provide a concise overview of airborne germ transmission as seen from a physics perspective .