Miasma theory
Miasma theory is an scientific theory no longer widely believed in where people believed that bad air known as miasma (a Greek word) caused many diseases such as cholera, chlamydia, and the Black Death. The theory also held that the miasma was caused by rotting or decomposing foods and organic matter.
It was made popular by Greek philosopher and physician Hippocrates in the fourth century B.C.[1] It would later spread to places in Europe and China. The theory stopped being used by scientists around the year 1880. The miasma theory was replaced by the germ theory of disease. This means that specific germs caused disease instead of miasma.