Public health

Public health is the organized effort of a society to keep people healthy, focusing on whole populations, from a single neighborhood to an entire country, rather than on individual patients. Where clinical medicine mostly treats people after they fall ill, public health tries to stop illness and injury from happening in the first place, working through research, education, services and policy.

Its work is wide-ranging: tracking and investigating disease outbreaks, running vaccination programs, keeping air, water and food safe, promoting healthy eating and exercise, supporting mothers and young children, preparing for emergencies, and pressing for laws such as smoke-free indoor air, seatbelt use and workplace safety standards. Epidemiology is often called its basic science, because it measures who becomes ill, where and why, and so shows where action is needed. The field also examines the social and economic conditions that shape health and the unfair differences in health between groups.

Much of the rise in life expectancy over the past century is credited to public health measures such as clean water, vaccines and tobacco control. People in the field include epidemiologists, environmental health scientists, health educators, data scientists and policy makers.