Epidemiological evidence on the carcinogenic risk of air pollution

In summary, higher lung cancer morbidity and mortality in urban than in rural areas and the presence of carcinogens in polluted air suggest that smoking habits and specific occupational exposures cannot account for all the urban air pollution may play a role in this disease. Surveys of lung cancer have shown that differences in excess. Positive correlations between lung cancer death rates and indices of pollution in different places, the experience of migrants and a possibile decline in lung cancer mortality with decline in pollution provide support for the view that air pollution is a factor in this disease. But the effect of pollution cannot be large. It is likely to be a small fraction (possibly a tenth) of the effect of cigarette smoking.