Spatial and temporal patterns of airborne metal pollution: the value of low technology sampling to an environmental epidemiology study.

To investigate an epidemic of respiratory cancer in Armadale, central Scotland, its air pollution was studied. During a period of 18 months, low technology samplers were exposed at 47 sites in the town to monitor the local variations in contamination by atmospheric metals. The samplers were two types of lichen and two types of moss, one of each type being a transplant and the other an in situ sampler. Following each exposure, the comparability of the samplers' uptake and retention of the metals was assessed. The sources of the metals and the effects of environmental variables on the pollution patterns were investigated through statistical analyses of spatial and temporal trends in the data. The spatial patterns of the metals indicated the steel foundry in the town as the major source of most of the pollutants. The temporal patterns, although less statistically significant, suggested the pollution might have been affected by some meteorological factors and by the foundry's output, but not by the output of the other main industry in the town, i.e. a brickworks. The types of sampler showed a general similarity of pollution pattern, but with some differences which indicated that some types of sampler were more suitable than others for particular forms of survey. Low technology sampling can provide information about short-distance and short-term changes in the patterns of airborne pollution by metals, thereby assisting the interpretation of epidemiological patterns of respiratory disease.