Florence Nightingale
The miasma theory was refuted by John Snow, who discovered the real cause of an outbreak in London. The cause was foul water from a water pump in Broad Street, London. Snow's work was published in 1855, but it was 30 years before the germ theory was generally accepted. Farr publicly acknowledged he was wrong in 1866, but Nightingale never really gave up the miasma idea. London's cholera epidemics stopped once the authorities built sewage treatment plants, delivered cleaner water, and built a system of underground pipes that kept sewage from seeping into the water supply.