Total and partial O2 and CO2 ductances in workers exposed to inhalation of cement-asbestos

The aim of the study was to assess the efficiency of the respiratory system in ensuring the correct dynamics of respiratory gases in subjects chronically exposed to the inhalation of asbestos-cement dust but not yet suffering from parenchymal asbestosis, via measurement of total and partial O2 and CO2 ductance coefficients (Du). Two groups of male workers of working age were selected, the first consisting of 22 workers employed on the manufacture of asbestos-cement products, the second consisting of 26 workers who had never been exposed to the inhalation of significant concentrations of occupational respiratory irritants. The two groups were comparable for age, smoking, and normal spirometric parameters for FVC, FEV1 and PEF, and were free of any type on interstitial lung disease according to ILO standards. In the exposed group, all O2 and CO2 ductance coefficients were significantly lower than in the non-exposed, except DuBCO2 (alveolar-capillary ductance for CO2). Measurement of O2 and CO2 lung ductances at rest thus revealed an impairment of the diffusion and of the interpulmonary exchange of blood and air in subjects chronically exposed to the inhalation of asbestos-cement dust. In the sample under study, such impairment preceded lung damage detectable by spirometric and radiological tests and was an obstacle not only to oxygen intake but also to the elimination of carbon dioxide.