John Snow (1813-1858) was an English physician often cited as a pioneer in using spatial analysis to solve practical problems. He is best known for his role in the 1854 cholera outbreak in Soho, London. The prevailing theory at the time was that cholera was caused by "miasmas" of bad air. Snow supported the alternative theory that it is caused by germs in contaminated water. After talking to victims of the 1854 cholera outbreak, he concluded that the disease was being spread by water from a contaminated pump on Broad Street, and he convinced the authorities to remove the pump handle to stop it form being used. Snow later produced a famous dot map showing the clustering of cholera cases around the Broad Street pump, as part of a cmapaign to push the germ theory and call for improved sanitation facilities in London.
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