In China, people pour leftover Traditional Chinese Medicine onto public roads, believing it can ward off illness, with a superstition dating back to the Tang dynasty.

While walking along China’s roads, it is not uncommon to see leftover herbs scattered on the surface. This is not some random dumping problem, it is in fact Traditional Chinese Medicine (TCM) leftovers deliberately poured out by the people who cooked them. Superstition has it that by pouring the TCM leftovers on public roads, other people can walk and drive over them, thereby helping keep illness at bay. There is a folk legend that the habit originated in the Tang dynasty (618–907). Sun Simiao,...