FIGURE 1.

Illustration of the infection risk in the close‐range zone (in light green, representing a breathing case) and that in the remainder of a room (long‐range zone). The infection risk reduces as the inter‐personal distance increases, as shown by the thick gray line. The spread of the expired jet depends on head/body movement. When the jet spread angle is narrow, passive tracer‐gas decay follows the 1/d rule, where d is the distance; when the angle is wide, the 1/d² rule applies