The Public Health Approach is a way of looking at tacking a disease or other public health issue.
Step One: Data
The first stage in any public health approach is to be clear about what the problem is. To do that you need information or data about what the problem is, who it is affecting, when, where and to what extent.
John Snow and the Broad Street Pump
A great example of the first stage of the public health approach is the story of John Snow (not the one from Game of Thrones) and the Broad Street Water pump. John Snow lived in London at the time of a major outbreak of cholera in Soho the 1850s. At that time many people had no access to clean water or sanitation and the Broad Street water pump was where many of them got their drinking water. By carefully mapping where the cases of cholera were and by noting where those people got their drinking water he was able to conclude that the source of the infection was the Broad Street water pump. It turned out that the water was contaminated by sewage causing people became infected with cholera.
Snow’s investigation is a perfect example of the first stage of a public health approach which is to gather data on the problem and his actions led to improved sanitation and saved many lives.