1. Containing, pertaining to, or relating to harmful vapors: The miasmatical region near where Jim lives gives off noxious effluvia or a foul-smelling outflow of vapors; especially, a gaseous waste.
2. Diseases caused by unhealthy fumes: It is believed that the Romans were the first to invent a sewage system, thereby diverting miasmatical effluvia into and through the drains and out of the cities.