Miasma theory

The miasma theory (also called the miasmatic theory) held that diseases such as cholera, chlamydia, or the Black Death were caused by a miasma (μίασμα, ancient Greek: "pollution"), a noxious form of "bad air", also known as night air. The theory held that the origin of epidemics was due to a miasma, emanating from rotting organic matter. Though miasma theory is typically associated with the spread of disease, some academics in the early nineteenth century suggested that the theory extended to other conditions as well, e.g. one could become obese by inhaling the odor of food.

The miasma theory was accepted from ancient times in Europe, India, and China. The theory was eventually given up by scientists and physicians after 1880, replaced by the germ theory of disease: specific germs, not miasma, caused specific diseases. However, cultural beliefs about getting rid of odor made the clean-up of waste a high priority for cities.

The word miasma comes from ancient Greek and means "pollution". The idea also gave rise to the name malaria (literally "bad air") through medieval Italian.

Miasma was considered to be a poisonous vapor or mist filled with particles from decomposed matter (miasmata) that caused illnesses. The miasmatic position was that diseases were the product of environmental factors such as contaminated water, foul air, and poor hygienic conditions. Such infection was not passed between individuals but would affect individuals within the locale that gave rise to such vapors. It was identifiable by its foul smell. It was also initially believed that miasmas were propagated through worms from ulcers within those affected by a plague.

In India, there was also a miasma theory and the Indians take credit for being the first to put this miasma theory into clinical practice. The Indians invented paan, a gambir paste, that was believed to help prevent miasma; it was considered as the first antimiasmatic application. This gambir tree is found in Southern India and Sri Lanka.

In the 1st century BC, the Roman architectural writer Vitruvius described the potential effects of miasma (Latin nebula) from fetid swamplands when visiting a city:

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