The diseases related to asbestos exposure (pulmonary fibrosis, broncogenic carcinoma and mesothelioma) are of widespread interest and involve different socio-economic groups of subjects. Since these pathologies have a wide diffusion in the industrial world, we carried out an investigation on two populations occupationally exposed to air pollution and asbestos fibre inhalation (164 traffic policemen of the municipal district of Rome and 218 railwaymen) and on a control group (119 residents in a rural district of Perugia) for the detection of asbestos bodies in the sputum. The results obtained from traffic policemen and railwaymen workers differred significantly from those of the control group. The presence of asbestos bodies in traffic policemen seems to be determined by a strong synergetic effect between gaseous urban pollution, cigarette smoking habits and asbestos dust arising from car brakes and building materials, whereas, in railwaymen it seems to be more directly correlated to exposure.