Effluvium refers to vapours or exhalations once thought to transmit disease, especially before germ theory was understood. In earlier medical thought, foul air arising from decay or stagnant environments was believed to cause illness. Literary works adopted the term to describe oppressive atmospheres or subtle influences spreading through a place. In poetry effluvium often symbolises corruption, decay, or unseen forces that affect the body and mind, reinforcing themes of hidden danger in the natural or social environment.

Effluvium refers to vapours or odours once believed to carry disease. In earlier centuries people thought harmful miasmas spread illness through the air. Poets use effluvium to evoke invisible corruption, decay, or poisonous influence. The word often appears in descriptions of rotting cities, polluted landscapes, or moral contamination. Because effluvium suggests unseen forces drifting through the air, it can symbolise subtle psychological or social dangers.