Cholera is a killer epidemic disease and it can cause passing away within hours after first symptons of disease appear. Ten thousands of British people died because of cholera between 1831 – 1854. In those days, cholera was thought to be spread by bad air until John Snow proves the disease is spread by the dirty water. However, convincing people about changing this accepted opinion is not an easy task for him although he is a British doctor. Snow believed that sewage contamination into the water was cause of the disease outbreak.
In 1854 Aug, London was again hit by a outbreak of cholera. Outbreak makes sick more than 500 people who live in London in 10 days. Snow negotiated with City Hall and closed street-pumps off in Broad Street. That night nobody died anymore in Broad Street.
John Snow can convince the authority to take action and save the people lifes with the power of the data. He produced a map that shows cholera death locations including death people counts for each location. As seen in the previous illustration, the largest loss appears in Broad Street. Moreover, he remarks steet-pumps on the map. Thus, he discovers significant correlation between steet-pumps and cholera deaths.
Interestingly, Robin Wilson – a blogger – digitalizes John Snow’s cholera map. This map version makes the discovery more understanable.
Actually, handle of the street pump in Broad Street was broken to close off.