The 1854 Broad Street cholera outbreak was a severe outbreak of cholera that occurred in 1854 near Broad Street (now Broadwick Street) in the Soho district of London, England, and occurred during the third cholera pandemic. This outbreak, which killed 616 people, is best known for the physician John Snow's study of its causes and his hypothesis that germ-contaminated water was the source of cholera, rather than particles in the air (referred to as "miasma").