Corrupted air (miasma)

In Florence in 1348, Boccaccio wrote, some people walked about holding flowers, sweet herbs, or spices to their noses, because the whole air seemed full of the stench of the dead, the sick, and medicines. They believed that foul air carried disease and that sweet smells could guard against it.

This belief, often called miasma, is very old. The Hippocratic work On the Nature of Man, from ancient Greece, blamed epidemics on bad air charged with some unhealthy matter given off into it. The doctor Galen, writing in Greek in the second century CE, said that plagues spread when people breathed air made rotten by decay, such as the air over unburied bodies after a battle or over swamps in summer. Bad air harmed most, he added, those who lived a life of ease, overeating and drinking.

Writers on the Black Death named both contagion, passing from person to person, and corrupted air. Later, in Venice, ship captains spoke to health officers through a window, from fear of plague-bearing air, and some explained the 40 days of quarantine as the time needed for bad air to leave bodies and goods. In the 1800s many doctors held that cholera came from corrupted air. In the first half of the 1800s, Swedish country doctors used smoke, burnt coffee, and vinegar to overpower foul smells. The historian Annelie Drakman argues that they used smell to find dangerous matter and decide what to clean. After the London outbreak of 1866, which William Farr traced to one water company, more and more doctors accepted that cholera spread through water. From the late 1870s, Swedish doctors called dirt harmful because it held bacteria, though stench stayed a warning sign.

Library texts show the belief at work. In The Plague Comes to Messina and Catania, the duke avoids towns because their air is infected. The Great Mortality in Paris, 1348–1349 reports that people blamed infected air and water, and that Jews were accused of corrupting them. In After the Mortality: Florence, 1348, rich families who shut themselves up in country houses with healthy air die anyway. As If the Whole World Had Changed traces corrupted air to crowded cities. Samuel Pepys chews tobacco against the smell in A London Diary of the Plague Year, 1665. In The Pump in Broad Street, 1854, John Snow argues instead that cholera spread through drinking water.