The Miasma Theory

The Miasma Theory was a historical belief that diseases were caused by "bad air" or miasmas—noxious vapors from decaying organic matter. People thought that these unpleasant smells could spread illness, especially in crowded or unsanitary conditions. This theory was prevalent before the discovery of germs and influenced public health measures, like improving sanitation and ventilation. Although it was eventually replaced by the germ theory of disease, which identifies microorganisms as the true cause of infections, the Miasma Theory underscored the importance of clean environments for health.