[Asbestos in brake and clutch factories. Results of an environmental survey]

Asbestos is an essential ingredient of friction materials: an environmental survey has been carried out in a brake and clutch factory to evaluate the exposure to airborne asbestos fibres. The measurement of the fibre concentrations has been carried out by means of personal and general air sampling on membrane filters, and subsequent counting by phase-contrast microscopy (400 X). In 17 out of 19 operations entailing exposure for a full shift, mean concentrations obtained by means of personal sampling exceeded 1 f/cc, in 11 they exceeded 2 f/cc; the maximum mean concentration value (7,2 f/cc) has been found at the preforming presses. The mean value for all the working operations was 2,8 f/cc. In addition total dust levels were determined: from a comparison between numerical and gravimetric concentrations, it appears that, for the same total dust level, the initial manufacturing stages have a greater asbestos risk; the relations between the results of the two analytical techniques are discussed. The results are compared with those reported in the literature for similar factories.