In Ancient Greek religion, a miasma was "a contagious power... that has an independent life of its own.
Until purged by the sacrificial death of the wrongdoer, society would be chronically infected by catastrophe.
As a result, a miasma contaminated the entire family of Atreus, where one violent crime led to another, providing fodder for many of the Greek heroic tales.
Attempts to cleanse a city or a society from miasma may have the opposite effect of reinforcing it.
This article relating to ancient Greek religion is a stub.