The association between employment in motor exhaust-related occupations and the risk for lung cancer was examined in 2,291 male cases of lung cancer and 2,570 controls in data pooled from three US case control studies carried out by the National Cancer Institute between 1976 and 1983. The researchers concluded that workers in motor-exhaust related occupations had a 50 per cent higher rate of lung cancer than in other occupations, after accounting for smoking. The authors note: “The 50 per cent excess risk for lung cancer associated with employment in motor exhaust-related occupations could not be explained by greater use of cigarettes or by other occupational exposures among these workers.”

R Hayes and others. Lung cancer in motor exhaust-related occupations, American Journal of Industrial Medicine, volume 16, number 6, pages 685-695, 1989.