How did the growth of cities affect public health in the 19th century?

During the 19th century, rapid urbanization driven by the Industrial Revolution had a profoundly negative impact on public health. As populations in cities like London, Leeds, and Liverpool surged, infrastructure failed to keep pace, leading to housing shortages and overcrowded, unsanitary living conditions.1

These conditions directly contributed to a sharp rise in death rates and the widespread prevalence of communicable diseases, such as cholera, typhus, and smallpox. The environmental filth associated with dense urban growth established a clear link between poor sanitation and disease, prompting the realization that safeguarding public health required systemic engineering and administrative intervention rather than just individual medical care.1

In response, the 19th century saw the birth of modern public health institutions. Governments began passing Public Health Acts to regulate water supply, sewage disposal, and housing. By the latter half of the century, the emergence of bacteriology and immunology allowed for more targeted, scientific approaches to controlling infectious diseases, ultimately laying the foundation for contemporary preventive medicine.12