Is the Armadale epidemic over? Air pollution and mortality from lung cancer and other diseases, 1961-82.

In Armadale, a town in central Scotland, the standardised mortality ratios (SMRs) for lung cancer were exceptionally high during 1968-74. A large cluster of cases was found in a residential zone downwind from a foundry. In the present study death certificates in the mortality registers of three town parishes were analysed for 1961-82 and the time trends of mortality from major categories of disease were examined. The distribution of mortality from lung cancer within Armadale's six residential zones was compared with that of the other diseases for the periods 1968-75 and 1976-82; the zone of particular interest was that containing the original cluster of lung cancer. The distribution of lung cancer was also compared with the pattern of air pollution by metals, collected by Sphagnum moss bags. The annual numbers of deaths from respiratory cancer in Armadale rose to a plateau in 1968-77; after a fall during 1978-80, the numbers returned in 1981 and 1982 to their previous high values. Between 1968-75 and 1976-82 the mean SMRs for all the disease categories except respiratory cancer rose. The SMR for total mortality in 1976-82 was the same as in preceding years when the standardised death rate for Armadale was the highest for Scotland in the annual reports of the Registrar General. In the zone with the highest mortality from lung cancer in 1968-75 the SMR for that disease continued to be higher than expected. That zone also showed the highest SMRs for cancer of the upper alimentary tract, cerebrovascular disease, hypertension, and coronary heart disease; its SMR for bronchitis was the second highest in the town. Pollution studies indicated that zones with high SMRs for respiratory and non-respiratory cancer were exposed to air pollution by metals. The temporal and spatial patterns are consistent with the view that the problem of mortality from cancer and non-malignant diseases in Armadale remains.