Fig. 1.

A schlieren image of two people talking approximately 1 m apart (adapted and annotated by the author, from reference (Tang et al. (2011))). Note the exhaled airflows produced by both individuals (indicated by dotted red lines), which quickly move across the gap between them, can be inhaled by the opposing individual. Essentially: ‘If I can smell the garlic on your breath, then I must be inhaling some of your exhaled air – and any viruses carried within it’. Full schlieren/shadowgraph videos of talking breathing, coughing, sneezing, laughing and singing are available at: https://www.youtube.com/watch?v=MaYcjyU6XT8&list=PL8pE_CuHoXJXZExcWwk_0tsqjT2Ydwsxg&index=1.