Conducted by epidemiological units from the Medical Research Council and the Arthritis and Rheumatism Council, the 1968 Rhondda Fach medical survey follows up earlier surveys in the valley. The first, in 1950 (archive footage is shown), used a mobile Mass X-Ray Unit, and the aim was to discover why some people developed the most serious form of pneumoconiosis - progressive massive fibrosis - whilst others did not. It became apparent that data on other common diseases (e.g. bronchitis, blood pressure, rheumatoid arthritis) could be acquired at the same time. In this way, it is claimed, the Rhondda Fach became the most medically examined community in the world and its population has made a notable contribution to medical research.

A campaign was mounted (in 1950) to encourage inhabitants to participate, with posters and loudspeakers used to encourage people to present themselves for x-ray and a local hall hired for the taking of case histories. 25,000 were examined in this first survey, with everyone over the age of five targetted.

By 1968, with the Rhondda Fach having suffered a big decline in its coal output and employment opportunities, a purpose-built clinic had been built in Ferndale. Field Survey Workers are seen visiting people and arranging for them to attend this clinic, where follow-up examinations are held, interviews conducted and x-rays carefully studied. It is painstaking work for the staff, and sometimes ultimately traumatic for those examined, some of whom were inevitably told, through a letter to their doctor, that a serious abnormality had shown up.